All India Difficult Airway Association 2025 guidelines for the management of unanticipated difficult airway in obstetrics under general anaesthesia

Abstract

Central neuraxial anaesthesia is the preferred approach for caesarean deliveries leading to less frequent use of general anaesthesia. The 2025 guidelines for managing general anaesthesia in obstetrics recommend rapid sequence induction and intubation for parturients requiring general anaesthesia for caesarean delivery. If the initial intubation attempt fails, the team should “Call for help for difficult airway” (Code D) and prioritise oxygenation (SpO₂ > 95%). Tracheal intubation may be attempted by a more experienced operator after re-optimising position and considering alternate airway devices. The primary anaesthesia team can opt for a 2^nd generation supraglottic airway (SGA) device as a rescue device or continue the anaesthetic using a face mask (FM). Maintaining oxygenation is critical. If satisfactory oxygenation is achieved with 2^nd generation SGA or FM, the decision to continue will depend upon maternal and fetal condition. If satisfactory ventilation cannot be maintained with 2^nd generation SGA or FM following failed tracheal intubation, the team declares “complete ventilation failure” and proceeds to surgical cricothyroidotomy. Should maternal cardiac arrest occur, proceed to “resuscitative hysterotomy” to improve chances of saving mother and baby. Post-resuscitation care should continue in the ICU to return the parturient to normalcy. Parturients may have a physiologically difficult airway in addition to anatomical reasons for airway difficulty. Specific steps to deal with associated pathophysiological changes constitute an important aspect of airway management in obstetrics. If a difficult airway is encountered, an “Airway Alert Card” must be given to the parturient and her responsible relatives to avoid similar life-threatening situations in future.

DISCLAIMER

These guidelines have been developed to help clinicians manage unanticipated difficult airways in patients using evidence-based recommendations or Delphi consensus opinions from airway experts, wherever evidence was lacking or weak. These guidelines do not represent the minimum standard of practice, nor are they a substitute for good clinical judgement. The recommendations in the guidelines assume that the airway operator has adequate experience with the devices and techniques described and that these are applied within the scope of their practice. Recommendations regarding the use of specific resources (devices, medications, or workforce) apply where these resources are available. These recommendations should be viewed as aspirational when this is not the case. While careful attention has been paid to provide accurate and updated information, the authors acknowledge that the literature related to airway management is rapidly changing, altering our attitudes and clinical practice. It is important to note that application of these recommendations in specific settings remains the responsibility of the clinician.

INTRODUCTION

Confidential Enquiries into Maternal Deaths in the United Kingdom, as well as reports of anaesthesia-related maternal mortality in USA, have indicated that central neuraxial anaesthesia is a safer alternative to general anaesthesia (GA) in obstetrics.[1,2] GA is typically chosen in cases where neuraxial anaesthesia has failed, the parturient is unwilling to undergo neuraxial anaesthesia, there is a coagulation abnormality, or there is a presence of a non-reassuring maternal and/or fetal status. As a result, airway complications continue to occur, resulting in maternal morbidity and mortality during caesarean deliveries under GA. In the United Kingdom, the incidence of failed intubation in the obstetric population is reported to be 1 in 224 anaesthetics.[3] This incidence of failed intubation is eight times greater than in the general population. Unfortunately, India does not have a nationwide registry to track such data, resulting in an unknown rate of maternal morbidity or mortality associated with failed intubation in this population.

Pregnancy-related changes in maternal anatomy, such as airway oedema and breast enlargement, increase the risk of airway complications, especially in obese parturients. Physiological changes, including decreased functional residual capacity and increased oxygen demand, narrow the safety margin for preventing hypoxia if a definitive airway is not secured at the earliest. Additionally, delayed gastric emptying and decreased lower oesophageal sphincter tone can result in regurgitation and aspiration. Onset of labour and bearing down during vaginal delivery may further worsen airway oedema, rendering a difficult airway even more challenging.[4]

A decline in the number of general anaesthetics for caesarean deliveries is reducing the exposure of anaesthesiology trainees to airway management in obstetrics. Additionally, the restriction of working hours in several countries is decreasing real-life clinical training opportunities. As a result, trainees are now less familiar with managing a general anaesthetic in the obstetric patient and are likely to struggle more with airway management in the obstetric population.[5,6]

HOW DO THE AIDAA 2025 GUIDELINES DIFFER FROM THE 2016 GUIDELINES?

The AIDAA 2016 Obstetric Guidelines[7] were described at a time when tracheal intubation was the preferred technique to provide GA for a caesarean delivery. While this basic tenet still remains, the past 2 decades have witnessed the increasing use of supraglottic airway (SGA) devices, especially the 2^nd generation SGAs, not only as a rescue device when tracheal intubation fails but also as a primary airway device for caesarean deliveries in select subgroups of parturients. Evidence in favour of the use of SGA devices (either as a rescue device or as a primary device) in obstetrics is presented in the current guidelines. The present guidelines also describe clinical situations wherein the anaesthetic may need to be continued via a face mask in the long-term interests of the mother and the baby. The clinical caveats that qualify such use of a face mask have been described.

Parturients have always been considered to be “full stomach”. Recent evidence concerning more liberal fluid intake once labour begins, and the use of gastric ultrasonography to identify parturients at risk of regurgitation and aspiration, has been outlined in the present guidelines. Preoxygenation techniques have also undergone refinement over the past 2 decades. The AIDAA 2025 guidelines emphasise the importance of supplementing conventional FM preoxygenation with low flow nasal oxygen (LFNO) or high flow nasal oxygen (HFNO) techniques during periods of apnoea to increase the “safe apnoea period” before a definitive airway is secured.

Maternal cardiac arrest can occur at any point during the induction of anaesthesia, maintenance, and recovery from anaesthesia. Current evidence in favour of timely “resuscitative hysterotomy” (earlier referred to as perimortem caesarean section) to enhance the chances of survival of both the mother and the baby has been elaborated in the current guidelines.

In summary, the current guidelines have distilled evidence from literature that has had a positive impact on the anaesthetic management of the parturient. We believe that incorporation of recent evidence as described in the AIDAA 2025 Obstetric Guidelines into our anaesthetic practice will ensure that the parturient will receive the best anaesthetic care as supported by recent literature. Though not meant to dictate a standard of care, taking cognisance of evidence presented in the AIDAA 2025 Obstetric Guidelines and tempering it with good clinical judgement will ensure a safe outcome for both the mother and the baby. This document should be read alongside the “All India Difficult Airway Association 2025 Guidelines for the Management of Unanticipated Difficult Airway in Adults under General Anaesthesia”[8]

METHODS

Based on literature review and discussion among Obstetric Guidelines Subcommittee Members, seven PICO (Patient/Population, Intervention, Comparison, and Outcome) questions were formulated to identify areas of research. Areas of research included adequate fasting duration in parturients; quantitating residual gastric volume using gastric ultrasound and ability to predict risk of aspiration; conventional preoxygenation, high-flow or low-flow nasal oxygenation, and effect of its continuation during the apnoeic period on peri-induction desaturation; succinylcholine versus rocuronium during rapid sequence induction and intubation; use of cricoid force and circumstances necessitating its release; role of videolaryngoscope versus direct laryngoscope; and role of 2^nd generation supraglottic airway devices as a primary airway device or a rescue device.

Systematic literature search, data extraction, and evidence synthesis were conducted for each PICO question. Literature search covering the period from January 2000 to December 2024 was performed in PubMed and Scopus databases using search strings tailored to each PICO question. The concept table, search strings, and PRISMA flowcharts outlining the search process for each PICO question are summarised in Appendices 1 to 10. All retrieved articles were imported into the Rayyan software (Rayyan Systems Inc., Cambridge, Massachusetts, USA; http://rayyan.qcri.org) for initial screening.[9] Two reviewers independently screened the titles and abstracts of each article and selected the final list of full-text studies for inclusion. A table of the shortlisted articles was compiled.

The evidence was summarised and recommendations were categorised according to the American Heart Association (AHA) Class of Recommendation and Level of Evidence for clinical strategies, interventions, treatments, or diagnostic testing in patient care.[10] Where evidence was absent or weak, the Steering Committee initiated a Delphi Survey process to reach consensus (75% and above) among airway experts.[11] Statements were included in successive Delphi rounds until stability criteria were met. Expert consensus statements were then drafted based on survey items that reached consensus. [Addendum 1] Complete details of the guideline development process and methodology, including the Delphi Survey process, are provided in the All India Difficult Airway Association 2025 guidelines for the management of unanticipated difficult airway in adults, obstetrics, and paediatrics and the management of at-risk extubations: Guideline development process and methodology.[12]

DESCRIPTION OF ALGORITHM

General anaesthesia is induced using rapid sequence induction and intubation [Figure 1]

Figure 1.

Algorithm for the management of unanticipated difficult airway in obstetrics under general anaesthesia

Rapid sequence induction and intubation (RSII) with application of cricoid force (CF) is still the preferred technique [Table 1] for inducing GA in parturients due to the high risk of aspiration. However, when the parturient is identified to be having a potentially difficult airway, the obstetrician, neonatologist, and anaesthesiologist must discuss and document management strategies in case tracheal intubation fails. The presence of a potentially difficult airway and the management options should be conveyed to the mother and relatives at the time of obtaining the written informed consent. Before starting preoxygenation with a flow of 10 litres per minute (LPM) using a well-fitting face mask during RSII, ensure that the patient is optimally positioned for tracheal intubation. Employ a nasal cannula to administer oxygen at 5 to 6 LPM, a flow that is well tolerated in a conscious patient. Following induction of anaesthesia, the flow rate through the nasal cannula can be increased to 10 to 15 LPM. High-flow nasal oxygen (HFNO) may also be used when available to enhance oxygenation when the parturient is apnoeic. [Table 1] Maintain uninterrupted oxygenation via the nasal cannula or HFNO during attempts at tracheal intubation or placement of a 2^nd generation SGA device as it extends the ‘safe apnoea time’ through the process of ‘apnoeic oxygenation’.[13,14] Successful tracheal intubation is confirmed by the presence of six or seven sustained capnographic waveforms.[15,16]

Table 1.

Summary of recommendations and best practice statements

Clinical Research Question	Recommendation/Best Practice Statement	Type of guidance	Class (Strength) of Recommendation	Level (Quality) of Evidence
Does videolaryngoscopy improve the success rate of intubation compared to direct laryngoscopy in parturients undergoing caesarean delivery under general anaesthesia?	Videolaryngoscopy is beneficial whenever intubation difficulty is anticipated or encountered.	Best Practice Statement	Class 2a	B-R
	Videolaryngoscopy may be considered as a primary technique for intubation compared to direct laryngoscopy in parturients undergoing caesarean delivery under general anaesthesia.	Best Practice Statement	Class 2b	B-R
Can a supraglottic airway (SGA) be used as a “planned primary airway device” for elective caesarean delivery?	Supraglottic airway is not recommended for use as a planned primary airway device for elective caesarean delivery.	Best Practice Statement	Class 3 Benefit = Risk	B-R
Does application of cricoid force prevent regurgitation and aspiration in parturients undergoing caesarean delivery under general anaesthesia?	Application of cricoid force may be considered during general anaesthesia for caesarean delivery.	Best Practice Statement	Class 2b	B-NR
Does high-flow nasal oxygen during preoxygenation and continued during apnoea versus face mask preoxygenation reduce peri-induction desaturation in parturients undergoing caesarean delivery under general anaesthesia?	High-flow nasal oxygen for preoxygenation followed by apnoeic oxygenation may be considered to reduce peri-induction desaturation in parturients undergoing caesarean delivery under general anaesthesia.	Best Practice Statement	Class 2b	B-NR
Compared to low-flow nasal oxygen (LFNO), does apnoeic oxygenation using high-flow nasal oxygen (HFNO) provide better oxygenation and reduce the risk of hypoxaemia during the apnoeic period in parturients undergoing caesarean delivery under general anaesthesia?	Either HFNO or LFNO may be considered for apnoeic oxygenation.	Best Practice Statement	Class 2b	C-EO
What should be the antral volume measured by gastric ultrasound to minimise the risk of aspiration in a full-term parturient undergoing caesarean delivery under GA?	An antral volume exceeding 1.5 mL/kg, assessed using gastric ultrasound in the right lateral decubitus position, may indicate a higher aspiration risk in full-term parturients undergoing caesarean delivery with general anaesthesia.	Best Practice Statement	Class 2b	B-NR
How long should a parturient be kept fasting before anaesthesia for caesarean delivery?	For elective caesarean delivery, parturients may consume clear fluids up to 2 hours and a light meal up to 6 hours before anaesthesia.	Best Practice Statement	Class 2b	B-NR

Failed tracheal intubation at first attempt and subsequent steps of airway management [Figure 1]

Should the first attempt at tracheal intubation fail, the anaesthesiologist should immediately “Call for help for difficult airway” (Code D),[17] re-optimise position, and ensure complete neuromuscular blockade before proceeding with the 2^nd attempt at tracheal intubation. Ideally, this attempt should utilise an alternate laryngoscope such as a videolaryngoscope, provided it is available and the attending anaesthesiologist is proficient in its use [Table 1]. Furthermore, the second attempt at tracheal intubation should also be performed by the most experienced team member in the operating room [Table 2].

Table 2.

Expert consensus statements using Delphi methodology

Clinical Question	Expert Consensus Statement	Consensus (%)
What is the maximum number of attempts at tracheal intubation that should be permitted to limit airway management-related complications in a parturient?	A maximum of 2+1 attempts at tracheal intubation (additional attempt done only by an experienced anaesthesiologist) should be permitted to limit airway management-related complications in a parturient.	83%
What is the maximum number of attempts at supraglottic airway (SGA) insertion that should be permitted to limit airway management-related complications in a parturient?	A maximum of two attempts at SGA insertion should be allowed to restrict airway management-related complications in a parturient.	79%
Should cricoid force (Sellick’s manoeuvre) be removed completely if it is causing difficulty for face mask ventilation?	Cricoid force (Sellick’s manoeuvre) should be removed completely if it is causing difficulty for face mask ventilation.	100%
Should cricoid force (Sellick’s manoeuvre) be removed completely if it is causing difficulty in the placement of an SGA?	Cricoid force (Sellick’s manoeuvre) should be removed completely if it is causing difficulty in the placement of an SGA.	96%
Should cricoid force (Sellick’s manoeuvre) be removed completely if it is causing difficulty for tracheal intubation because of a poor laryngeal view?	Cricoid force (Sellick’s manoeuvre) should be removed completely if it is causing difficulty for tracheal intubation because of a poor laryngeal view.	96%
During rapid sequence induction, should face mask ventilation be used during the apnoeic period before intubation in parturients undergoing caesarean delivery who are at a high risk of desaturation?	During rapid sequence induction, gentle face mask ventilation (with peak pressures limited to 20 cm H2O) should be used during the apnoeic period before intubation in parturients undergoing caesarean delivery who are at a high risk of desaturation.	100%
Should rocuronium be considered over succinylcholine for caesarean delivery at term if an adequate dose (16 mg/kg) of sugammadex is available to reverse neuromuscular blockade immediately after an intubating dose of rocuronium is administered?	Rocuronium should be considered over succinylcholine for caesarean delivery at term if an adequate dose (16 mg/kg) of sugammadex is available to reverse neuromuscular blockade immediately after an intubating dose of rocuronium is administered.	96%
Following a failed intubation, when satisfactory ventilation is achieved through a properly placed 2ndgeneration SGA, should general anaesthesia be continued to complete the caesarean delivery if fetal and/or maternal status is compromised?	Following a failed intubation, when satisfactory ventilation is achieved through a properly placed 2ndgeneration SGA, general anaesthesia should be continued to complete the caesarean delivery if fetal and/or maternal status is compromised.	100%
What should the obstetrician-anaesthesiologist team do when tracheal intubation and ventilation using a 2ndgeneration SGA have failed, spontaneous breathing has NOT returned, face mask ventilation is possible, and there is an immediate threat to the life of the fetus or mother?	The obstetrician-anaesthesiologist team should proceed to deliver the baby with continued application of cricoid force when tracheal intubation and ventilation using a 2ndgeneration SGA have failed, spontaneous breathing has NOT returned, face mask ventilation is possible, and there is an immediate threat to the life of the fetus or mother.	100%
What should the obstetrician-anaesthesiologist team do when tracheal intubation and ventilation using a 2ndgeneration SGA have failed, adequate spontaneous breathing has returned, it is possible to maintain oxygenation and anaesthesia with the face mask, and there is an immediate threat to the life of the fetus or mother?	The obstetrician-anaesthesiologist team should proceed to deliver the baby with continued application of cricoid force when tracheal intubation and ventilation using a 2ndgeneration SGA have failed, adequate spontaneous breathing has returned, it is possible to maintain oxygenation and anaesthesia with the face mask, and there is an immediate threat to the life of the fetus or mother.	100%
What should the obstetrician-anaesthesiologist team do when tracheal intubation and ventilation using a 2ndgeneration SGA have failed, and spontaneous breathing has returned but is inadequate for maintaining effective oxygenation and anaesthesia with a face mask, and there is an immediate threat to the life of the fetus or mother.	The obstetrician-anaesthesiologist team should administer an additional dose of muscle relaxant to facilitate ventilation and proceed to deliver the baby with continued application of cricoid force when tracheal intubation and ventilation using a 2ndgeneration SGA has failed, spontaneous breathing has returned but is inadequate for maintaining effective oxygenation and anaesthesia with a face mask, and there is immediate threat to the life of the fetus or mother.	96%

At this juncture, the anaesthesiologist can select between two devices to continue oxygenation: a 2^nd generation SGA device or a FM. If the FM is chosen, gentle ventilation should continue using a well-fitting FM with the adjustable pressure limiting (APL) valve partially closed to maintain circuit pressure below 20 cm H₂O. Airway adjuncts such as an oropharyngeal airway may be used to facilitate face mask ventilation. If a 2^nd generation SGA device is selected, the number of attempts should be limited to two [Table 2]. The advantages and disadvantages of various designs of these devices have been discussed in the section on supraglottic airway devices (vide infra).

While working between the three options of airway devices provided within the circular algorithm [Figure 1], the anaesthesiologist must keep a track of elapsed time and ensure that SpO₂ levels remain above 95% utilising FM ventilation before proceeding with tracheal intubation or placement of a 2^nd generation SGA device. If a suboptimal glottic view is encountered during laryngoscopy, or if difficulties arise during FM ventilation or SGA device placement, cricoid force should be completely released [Table 2].

A 3^rd attempt at intubation should be performed only by an experienced anaesthesiologist using a direct laryngoscope or a videolaryngoscope as deemed appropriate. This laryngoscopy also helps to evaluate the extent and nature of airway difficulty and forms the basis for subsequent decisions regarding airway management [Table 2].

Tracheal intubation fails in the hands of the most experienced anaesthesiologist – what next? [Figure 1]

The anaesthesiologist should choose between utilising a 2^nd generation SGA device or continuing with FM ventilation to ensure that the SpO₂ levels remain above 95%. Once satisfactory ventilation is achieved, the team should evaluate the stability of both the mother and the fetus. If both are reassuring, the best option is to awaken the patient and consider alternate anaesthetic techniques.

On the other hand, if maternal or fetal well-being is not reassuring, the obstetrician should proceed with baby delivery. Once ventilation is possible through the 2^nd generation SGA device, the anaesthesiologist must assess whether the SGA device is correctly sited. In the presence of an audible or quantifiable leak (indicating a suboptimally placed SGA device), the anaesthesiologist should continue the anaesthetic and the obstetrician should proceed to baby delivery. Following baby delivery, SGA-guided tracheal intubation over a flexible bronchoscope may be considered if appropriate resources are available. If the SGA device is well sited, the baby can be delivered using the SGA device as the final airway [Table 2]. However, if at any point in time, a previously well-sited SGA device fails to provide satisfactory ventilation, or the parturient has a ‘full stomach’ or the maternal status worsens (as can happen with massive blood loss or major fluid shifts), the anaesthesiologist should consider SGA-guided tracheal intubation over a flexible bronchoscope, provided the necessary equipment and expertise are available.

If successful ventilation has been achieved only with the FM, the anaesthesiologist has three possible clinical paths to follow [Table 2]: (i) If the parturient remains apnoeic, the anaesthesiologist should continue applying cricoid force and perform gentle positive pressure ventilation, ensuring that the circuit pressure does not exceed 20 cm H₂O, and proceed to baby delivery; (ii) if spontaneous breathing efforts have returned and are adequate, it is advisable to continue the anaesthetic with continued application of cricoid force and proceed to deliver the baby; (iii) if spontaneous breaths have returned but are inadequate, an additional dose of neuromuscular blocking agent should be administered, the anaesthetic should be continued with FM ventilation while maintaining cricoid force, and the baby should be delivered. In all three scenarios described above, the entire anaesthetic can be completed using an FM as the breathing circuit interface. Fundal pressure by an assistant to assist baby delivery and exteriorisation of the uterus should be avoided as both these manoeuvres can increase the chances of regurgitation of abdominal contents and aspiration in the presence of an unprotected airway.[18]

Complete ventilation failure – what next? [Figure 1]

‘Complete ventilation failure’ is the term used to describe a clinical situation of inability by the seniormost member of the team to ventilate through a tracheal tube, 2^nd generation SGA device, or FM after ensuring complete neuromuscular blockade. At this juncture, the team needs to ‘Call for additional help’ and declare ‘complete ventilation failure’, which is the trigger for performing an ‘emergency surgical cricothyroidotomy’. The scalpel-bougie technique is recommended. Percutaneous techniques such as a needle cricothyroidotomy with pressure-regulated jet ventilation or wide-bore cannula cricothyroidotomy may be used if equipment and expertise are available. However, both these percutaneous techniques are temporary measures and need to be converted to a surgical tracheostomy at the earliest once the emergency tides over. Surgical tracheostomy may be considered if an experienced surgeon is available.

Maternal cardiac arrest [Figure 1]

Failure to maintain oxygenation during any phase of obstetric airway management can result in maternal cardiac arrest. In the unfortunate event of a cardiac arrest, one should proceed to ‘resuscitative hysterotomy’ within 4 minutes of the cardiac arrest. This step would give the mother and the baby the best chance of survival.[19] If maternal resuscitation is successful, the mother is transferred to an intensive care unit for post-resuscitative care.

SUPPORTIVE LITERATURE

Preoperative patient evaluation

The obstetric team can collaborate with a dedicated anaesthesia team to identify clinical signs that may pose risks to anaesthetic care. Early identification of maternal medical issues and fetal concerns requiring GA is crucial as it allows the anaesthetic team to be prepared with a plan well in advance before labour begins. Obstetricians may be encouraged to perform a quick airway assessment using the “1-2-3 Rule”.[20] If this quick assessment indicates potential airway issues, the obstetric team should alert the anaesthesiologist for a more detailed evaluation. This proactive strategy aids in the timely identification of difficult airways, allowing for better team preparedness.

A comprehensive medical examination, including a detailed airway assessment, should be conducted in the third trimester and also during labour. It is vital to reassess the airway anatomy with the onset of labour, as the modified Mallampati class is known to change with advancing labour, making the airway more challenging.[4] For parturients scheduled to undergo caesarean deliveries, it is advisable to identify and mark the cricothyroid membrane using ultrasonography to provide emergency oxygenation in the event of complete ventilation failure. Additionally, the obstetric indications for surgery and the condition of the fetus must be carefully considered. The obstetrician, neonatologist, and anaesthesiologist should collaborate closely and arrive at a joint decision regarding the mode of delivery, particularly when failed intubation is encountered.

Preoperative fasting and ultrasonographic assessment of residual gastric volume

Delayed gastric emptying and increased intra-abdominal pressure from the gravid uterus increase the risk of pulmonary aspiration in parturients, especially during labour and with opioid use. Traditionally, women have been advised to avoid eating or drinking once labour has started to minimise this risk before possible emergency caesarean deliveries. However, strict adherence to this rule can lead to ketone production and maternal discomfort.[21]

Current evidence suggests a fasting period of 6 to 8 hours for solids before elective caesarean deliveries and for women in active labour.[22] Clear liquids such as water, isotonic drinks, fruit juices without pulp, and black coffee or tea without milk can be consumed up to 2 hours before surgery. Liquid intake for women in active labour should be adjusted based on their risk of regurgitation and aspiration, particularly in cases of morbid obesity, diabetes, or potential urgent caesarean delivery.[23,24] A more liberal fluid intake can be considered in other situations.

Gastric ultrasound has become an important tool for assessing gastric volume and predicting risk of aspiration. Both qualitative assessment such as the Perlas score (Grades 0, 1, and 2) and quantitative evaluations of gastric antral cross-sectional area (CSA) and volume offer insights into whether the stomach is full or empty.[25] The cut-off values for high aspiration risk vary, with gastric antral CSA ranging from 3.8 cm² to 10.3 cm² and gastric volumes from 0.8 to 1.5 mL/kg.[25,26,27,28] Generally, a cut-off of over 1.5 mL/kg is used to identify a ‘full’ stomach. Studies suggest that ultrasound assessments should occur in semirecumbent and right lateral decubitus positions to obtain the best view of the gastric antrum. Evidence indicates that pregnant women not in labour have similar gastric volumes to non-pregnant women, suggesting that they are less likely to be classified as “full stomach” or “at risk” of aspiration. However, some fasted pregnant women not in labour show higher gastric volumes. Notably, women in labour and those with a body mass index of over 30 kg/m² exhibit higher gastric antral CSA. Furthermore, adequate analgesia during labour can lower gastric volume as pain is known to delay gastric emptying.

As the Strength of Recommendation is only 2b based on the quality of evidence available (B-NR), we recommend that it is best practice to use ultrasonography to evaluate residual gastric volume in parturients scheduled to undergo caesarean delivery.

Premedication

Premedication is aimed at reducing gastric acidity, minimising gastric volume, and enhancing gastric motility. For decreasing gastric acidity, intravenous options include ranitidine (50 mg slow injection) or pantoprazole (40 mg) given 45 to 60 minutes before surgery. Additionally, metoclopramide (10 mg) can improve gastric emptying and increase the tone of the lower oesophageal sphincter.[29,30] Non-particulate antacids, such as 0.3 M sodium citrate (15 to 30 mL), may be given 30 minutes before caesarean delivery to elevate gastric pH. Reducing gastric acidity is essential for all patients undergoing caesarean deliveries as neuraxial anaesthesia may sometimes need to be converted to GA.

Preparation

Prepare the operating suite for a caesarean delivery. The checklist should include a functional anaesthesia workstation, suction equipment, a tilting operation table, a neonatal resuscitation area, and labelled syringes with anaesthetic/emergency drugs. Necessary airway equipment includes various sizes of anaesthesia masks, oropharyngeal and nasopharyngeal airways, short-handled direct laryngoscopes (with Macintosh and McCoy blades), videolaryngoscopes with standard and hyperangulated blades, endotracheal tubes, airway introducers, 2^nd generation SGA device, and equipment for emergency cricothyroidotomy. Additionally, having a ‘difficult airway cart’ nearby and a senior anaesthesiologist on standby is essential.[17]

Patient position

Pregnant patients can develop supine hypotension syndrome while lying on their back due to aortocaval compression by the gravid uterus. They should therefore be transported from the labour room to the operation theatre in the left lateral position. In addition, once the parturient is transferred onto the operating table, a wedge should be placed under the right buttock to provide left uterine displacement. A profile view from the side should ensure that there is adequate space between the chin and upper chest to facilitate the unhindered introduction of the short-handled laryngoscope. A ramped position can be obtained using pillows and folded sheets to support the back and head so as to align the external auditory meatus with the suprasternal notch. This position is specially indicated in obese patients.[31] A head-up tilt of 20° to 30° can further aid intubation and improve efficiency of preoxygenation.[32]

Preoxygenation and anaesthetic induction

Preoxygenation is initiated by administering oxygen at 10 L/min for 3 to 5 minutes using a well-fitting face mask; higher flows may be used if tolerated. An end-tidal oxygen fraction of >0.9 indicates adequate preoxygenation.[33,34] During tracheal intubation or placement of an SGA device, continued oxygenation via a nasal cannula at 15 LPM or more (or HFNO if available) significantly improves the ‘safe apnoea period’ through apnoeic oxygenation.[35]

Anaesthesia should be induced using titrated doses of an induction agent until loss of consciousness. In haemodynamically stable patients, propofol (1 to 2 mg/kg) is a suitable agent, while etomidate (0.2 to 0.3 mg/kg) is recommended for haemodynamically unstable patients. For neuromuscular blockade, succinylcholine hydrochloride (1.5 mg/kg) is commonly used, with rocuronium (0.9 to 1.2 mg/kg) as an alternative when succinylcholine is contraindicated. Although rocuronium and sugammadex are currently available, succinylcholine is often preferred for RSII due to concerns regarding the effect of sugammadex on Apgar scores and potential hypersensitivity reactions.[36] If rocuronium is chosen for RSII, it is crucial to ensure that an adequate quantity of sugammadex (16 mg/kg) is readily available. In difficult airway situations where the decision has been taken to awaken the patient, administering the full dose of sugammadex is advisable to prevent residual neuromuscular blockade.

Modified RSII allows gentle face mask ventilation with the APL valve set to ≤20 cm H₂O and provision of small tidal volume breaths until complete muscle paralysis ensues.[37,38] This approach can effectively prolong safe apnoea time in parturients and also assess the ability to ventilate using a face mask. Depending on local protocols, laryngoscopy may be performed using a conventional laryngoscope or a videolaryngoscope. If the glottic view is inadequate, cricoid force should be fully released.[37] A suction device with a Yankauer tip should always be available to manage regurgitation. Alternate laryngoscope blades, such as McCoy or Miller blades, should be readily available. Successful intubation is confirmed by the presence of six or seven sustained capnographic waveforms.[15,16] After verifying successful intubation and inflating the cuff, the assistant can release cricoid force and secure the endotracheal tube with tape before allowing the surgery to start.

Application of CF can distort the pharynx and hinder FM ventilation, placement of an SGA device, laryngoscopy, and tracheal intubation.[37,39] The anaesthetic assistant should be prepared to release the CF completely to achieve satisfactory FM ventilation, proper placement of the SGA device, and tracheal intubation. Difficulty attaining adequate tidal volumes may indicate that the applied CF is excessive, and releasing it can often improve ventilation.[37]

Videolaryngoscopes – a preferred option when direct laryngoscopy fails?

Numerous studies indicate that videolaryngoscopes consistently improve glottic visualisation and have become the preferred choice for anticipated or encountered difficult intubations. In cases of failed intubation during a caesarean delivery, these devices should be used if expertise and necessary equipment are available.[40] While videolaryngoscopes should be available in all obstetric operating rooms, conclusive evidence for their universal use as the first-line device in all cases is still lacking. Guidance on selecting the best videolaryngoscope for obstetric patients is also limited.

Supraglottic airway devices – what is their role in obstetric anaesthesia?

Supraglottic airway (SGA) devices have been widely used in non-obstetric settings as a primary airway tool or a rescue device when intubation fails. Due to the high risk of regurgitation and aspiration in pregnant patients, SGA devices were initially used in obstetrics only as a rescue option when intubation was unsuccessful. Between 2004 and 2011, several case reports highlighted the effectiveness of 2^nd generation SGA devices in rescuing parturients following failed intubation.[41,42,43,44,45,46,47] In a study of 1095 women receiving GA for caesarean delivery, 4 patients in whom intubation failed were successfully managed using an SGA device.[48] The supportive role of the SGA device has also been acknowledged in an Editorial as well as two Narrative Reviews.[32,49,50]

With increasing use of the SGA as a rescue device in obstetrics, four studies originating from the same country reported on over 5350 parturients in whom the SGA device was used as the planned airway interface. Notably, patients with difficult airways, a mouth opening less than 2.5 cm, or a pre-pregnancy body mass index over 30 kg/m² were excluded from these studies. All patients were fasted for 4 to 6 hours before surgery and received 50 mg of intravenous ranitidine 1 hour before surgery. The Classic LMA,[51] ProSeal LMA^TM,[18] and LMA Supreme^TM[52,53] were used as the planned SGA devices in these large prospective observational series. Three retrospective observational studies also strengthened the view that the LMA Supreme^TM could be used safely as a primary airway interface for caesarean deliveries.[54,55,56]

Four randomised controlled trials including 1140 parturients compared the clinical performance of the endotracheal tube versus a second-generation SGA device. In two of these trials, the i-Gel was declared to be clinically safe when compared to endotracheal intubation.[57,58] The ProSeal LMA^TM and LMA Supreme^TM were also clinically comparable to tracheal intubation.[59,60] However, the numbers included in each of these randomised controlled trials were not adequately powered to detect whether one device was superior to the other for preventing aspiration.

A systematic review and meta-analysis of 14 articles showed that while SGA devices have a reasonable success and safety profile, the results were insufficient to determine the incidence of pulmonary aspiration. Therefore, whether SGA devices are equivalent to tracheal intubation for elective caesarean deliveries remains unclear. More research is needed before SGA devices can be recommended as the first-choice airway device for caesarean deliveries.[61] A review by Metodiev recommends that when an SGA device is appropriately positioned and functioning effectively, it should continue to be utilised for oxygenation.[62]

Second-generation SGA devices provide better airway seal and, when properly placed, provide near-complete separation of the gastric and respiratory tracts. As described by Wong et al.,[63] SGA devices can also facilitate fibreoptic-guided intubation. ‘Supraglottic airway-guided fibreoptic bronchoscopic intubation’ goes by the acronym ‘SAGFBI’. Some SADs, such as the Classic LMA (cLMA), i-Gel, Ambu AuraGain, Air-Q, and LMA Protector (‘wide SADs’), have broad enough ventilation channels to allow insertion of a standard tracheal tube by the direct SAGFBI method. Other SADs, such as the ProSeal LMA and LMA Supreme, have ventilation channels that are too narrow (‘narrow SAD’) for a standard tracheal tube to be inserted directly. As narrow SADs preclude direct SAGFBI, indirect methods (such as using an Aintree Intubation Catheter) must be chosen. As direct SAGFBI is more practical, a wide 2^nd generation SAD is preferred. If 6.0 mm ID tracheal tubes are to be used for SAGFBI, microlaryngeal tubes are preferred as they are longer and have adult-size cuffs, and cuff inflation at the level of the vocal cords can be avoided.[63]

Second-generation SGA devices are a safe “rescue” option for caesarean deliveries when tracheal intubation fails during rapid sequence induction. However, current literature does not support their use as primary airway devices as their safety in preventing aspiration has not been well substantiated. For fibreoptic bronchoscopic intubation through a 2^nd generation SGA device used as airway rescue, wide SADs are preferred over narrow SADs as the latter require indirect methods for tracheal intubation.

Physiologically difficult airway in parturients

Thus far, we have considered the management of an anatomically difficult airway in the parturient. However, there are several situations unique to the parturient where physiological compromise can influence airway management [Figure 2]. Physiological changes associated with pregnancy – such as increased oxygen consumption in the face of decreased functional residual capacity, and increased cardiac output in the presence of decreased systemic vascular resistance – can shorten ‘safe apnoea time’. Hypoxia associated with cardiorespiratory diseases complicating pregnancy can compound this adverse effect on safe apnoea time. Use of noninvasive ventilation or high-flow nasal oxygen, as is appropriate under these circumstances, can improve oxygenation and provide a safety net before attempts at securing the airway. Ventilatory management in pregnancy can take one of two forms: noninvasive ventilation and conventional ventilation.[64] Noninvasive ventilation (NIV) is a useful technique for short-term ventilatory support in pregnant patients who are alert and have rapidly reversible causes. One must bear in mind the risk of aspiration while using NIV. Conventional ventilation should be aimed at achieving a maternal PaO₂ greater than 70 mmHg. Hyperventilation and respiratory alkalosis must be diligently avoided to prevent uterine vasoconstriction. Maternal PaCO₂ in the range of 27 to 34 mmHg provides the ideal gradient to facilitate placental excretion of fetal carbon dioxide.

Figure 2.

Aetiology and management principles of a physiologically difficult airway in a parturient. AFE = Amniotic fluid embolism, APH = Antepartum haemorrhage, CHD = Congenital heart disease, FRC = Functional residual capacity, HFNO = High flow nasal oxygen, ICH = Intracranial haemorrhage, LSR = Laryngosympathetic response, MI = Myocardial infarction, MV = Mechanical ventilation, NIV = Noninvasive ventilation, O₂ = Oxygen, OSA = Obstructive sleep apnoea, pH = Puissance of hydrogen, PaCO₂ = Arterial carbon dioxide tension, PAH = Pulmonary artery hypertension, PE = Pulmonary embolism, POCUS = Point-of-care ultrasound, PPCM = Peripartum cardiomyopathy, PPH = Postpartum haemorrhage, RV = Right ventricular, SVR = Systemic vascular resistance

Hypotension due to blood loss or sepsis needs to be addressed and appropriately managed with intravenous fluids, blood products, and vasopressors as appropriate.[65,66] Management of metabolic acidosis arising from any cause needs to be dealt with as indicated in the algorithm. Point-of-care ultrasound (POCUS) can help identify the exact aetiology of right ventricular dysfunction (pressure/volume overload or myocardial dysfunction), thereby helping the anaesthesiologist to initiate appropriately targeted therapies.[67]

Parturients with accelerated hypertension are at risk of intracranial haemorrhage or myocardial infarction with the rise in blood pressure associated with laryngoscopy and intubation. Pharmacological suppression of laryngosympathetic responses must be considered to circumvent this problem.[67] Some of the intravenous medications that may be administered as a bolus before laryngoscopy and intubation include the following: lignocaine (1–1.5 mg/kg given 90 seconds prior), esmolol (0.5 to 2 mg/kg given 1 to 2 minutes prior), labetalol (5 to 10 mg given 5 minutes prior), fentanyl (1 to 2 microgram/kg given 2 to 3 minutes prior), and remifentanil (0.5 to 1 microgram/kg given 1 minute prior). Medications that need to be administered as an infusion 10 to 20 minutes before laryngoscopy and intubation include magnesium sulphate 30 to 50 mg/kg or dexmedetomidine 0.5 to 0.75 microgram/kg.

It is crucial for the anaesthesiologist managing a parturient to recognise that physiological changes associated with pregnancy, as well as changes in body physiology resulting from pathophysiological conditions often seen in pregnancy, can convert an anatomically normal airway in a parturient into a “high-stakes situation”. The obstetric anaesthesiologist will do well to keep in mind these physiological and pathophysiological changes to achieve the final goal of “a happy mother and a healthy baby”.

Reporting a difficult airway

Communication of information concerning patients with difficult airways is a vital component in avoiding future airway management difficulties.[68] The 2013 American Society of Anesthesiologists Practice Guidelines for the management of a difficult airway recommend that patients be notified of their difficult airway by a written report or letter, including a summary of the airway difficulty encountered and subsequent steps taken during airway management to deal with these difficulties. The Canadian Airway Focus Group provides similar advice. The All India Difficult Airway Association (AIDAA) recommends handing over an “Airway Alert Card” to the parturient and her relatives, describing the nature of airway difficulty encountered and the subsequent management and outcome.[17]

SUMMARY OF RESEARCH QUESTIONS

Research Question 1

Does videolaryngoscopy improve the success rate of intubation compared to direct laryngoscopy in parturients undergoing caesarean delivery under general anaesthesia? [Appendix 1][7,32,40,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84]

Following review by AS and SRS, a total of 19 articles were included in the analysis comprising one meta-analysis [Howle R (2021) Level A],[40] a systematic review with decision analysis [Krom AJ (2017) Level B-NR],[71] and one randomised controlled trial [Honarmand A (2024) Level B-R].[70] All other review articles, guidelines, and observational studies were graded as Level C-LD or C-EO.

The meta-analysis by Howle R[40] (2021, Level A) included four RCTs (428 participants), nine observational studies, and 35 case reports or series (100 participants). With first pass success and intubation time as primary outcomes, results indicated equivocal results with first pass success when videolaryngoscopy was compared with direct laryngoscopy performed by an experienced operator. But videolaryngoscopy showed better results as primary tools for anticipated difficult intubation and as rescue after failed direct laryngoscopy in parturients. This finding suggests that videolaryngoscopes should be available in obstetrics settings.

Honarmand A (2024, Level B-R)[70] compared GlideScope VL with Macintosh direct laryngoscope and found shorter intubation time (10.15 ± 2.61 seconds vs 12.80 ± 1.86 seconds; P = 0.001), better first attempt success rate (91.1% vs 84.4%; P = 0.003), and better haemodynamic stability in parturients.

Across various studies, including meta-analyses, cohort studies, and review articles, all types of videolaryngoscopes were consistently found to enhance glottic visualisation. Videolaryngoscopy is the preferred tool when difficulty is anticipated or encountered. Evidence highlights the need for the availability of a videolaryngoscope device in all obstetric units. With regard to the universal use of videolaryngoscopy for obstetrics patients, the evidence is inconclusive at present. Guidance on the selection of the most appropriate device among available videolaryngoscopes is also lacking. There is also the issue of universal availability of the device and the expertise to use it when available.

Best Practice Statement: Videolaryngoscopy is beneficial whenever intubation difficulty is anticipated or encountered if expertise is available.

Strength of Recommendation: Class 2a, Level of Evidence: B-R

Best Practice Statement: Videolaryngoscopy may be considered as the primary technique for intubation if expertise is available.

Strength of Recommendation: Class 2b, Level of Evidence: B-R

Research Question 2

Can a supraglottic airway (SGA) be used as a “planned primary airway interface” for elective caesarean delivery? [Appendix 2][18,51,52,53,54,55,56,57,58,59,60,61,62,63]

Research Question 3

After successful rescue of the airway with a 2^nd-generation supraglottic airway, is it advisable to proceed with this device for a planned caesarean delivery? [Appendix 2][32,41,42,43,44,45,46,47,48,49,50]

The review was done by VR and GB. A total of 25 articles were selected for the final summary table, 14 for the use of SGA as a primary airway interface and 11 for rescue after failed intubation following GA for caesarean delivery.

Supraglottic airways have been used in many non-obstetric situations as a primary airway interface or as a rescue device when intubation fails. Because of the high risk of regurgitation and aspiration in the parturient, supraglottic airways were first used in the obstetric patient only as a “rescue device when conventional tracheal intubation had failed”. Between the years 2004 and 2011, there were several case reports highlighting the role of 2^nd-generation supraglottic airways that were used to rescue a parturient in whom tracheal intubation failed as a part of RSII. (Awan 2004, Vaida 2004, Keller 2004, Cook 2005, Sharma 2006, Berger 2011, Minville 2004 [C-LD])[41,42,43,44,45,46,47] While the ProSeal LMA was the rescue device in five of these case reports, the i-Gel was used in one. In one report, the intubating LMA used as a rescue device later served as a conduit for tracheal intubation. In a prospective observational study (McDonnell et al., 2009 B-NR)[48] of 1095 women receiving GA for all categories of caesarean delivery, four parturients in whom intubation failed were rescued with a supraglottic airway device. While the Classic LMA and Intubating LMA were used in one patient each, the ProSeal LMA was used in two patients. The supportive role of the supraglottic airway has also been acknowledged in an Editorial (Paech 2010,[49] [C-EO]) and two Narrative Reviews (Devroe 2015,[50] Patel 2020[32] [C-EO]).

With increasing use of the supraglottic airway as a rescue device in obstetrics, four prospective observational studies (originating from the same country where the majority of women opt for GA for caesarean delivery) (Han 2001, Yao 2012, Li 2017, Halaseh 2010 [B-NR])[18,51,52,53] reported a total of over 5350 parturients in whom a supraglottic airway was used as a primary airway interface for elective caesarean deliveries. Notably, these parturients were carefully selected to exclude those with known or suspected difficult airway, anticipated difficult intubation, mouth opening < 2.5 cm, and patients whose pre-pregnancy body mass index was >30 kg/m². In addition, all these patients were adequately fasted for 4 to 6 hours and received IV ranitidine 50 mg an hour before surgery. The Classic LMA, ProSeal LMA, and LMA Supreme were used as the planned supraglottic airway device in these large prospective observational series. Three retrospective observational studies (Geng 2017, Fang 2018, Geng 2023 [B-NR)[54,55,56] also strengthened the view that the LMA Supreme could be used safely as a primary airway interface for caesarean deliveries.

Four high-quality randomised controlled trials (Ahmed 2015, Panneer 2017, Saini 2016, Yao 2019 [B-R])[57,58,59,60] consisting of 1140 parturients compared the clinical performance of endotracheal intubation with a 2^nd generation supraglottic airway. In two of these RCTs, the i-Gel was compared with endotracheal intubation and found to be clinically safe. The ProSeal LMA and LMA Supreme were also found to be clinically comparable to tracheal intubation. However, the numbers included in each RCT were not powered enough to detect whether one device was superior to the other for preventing aspiration.

A systematic review and meta-analysis (White, 2020) [A][61] of 14 articles with levels of evidence ranging from Grade A to Grade C reported that despite the reasonable insertion success rate and safety profile of supraglottic airways demonstrated, the analysis remained underpowered to detect the incidence of pulmonary aspiration. Overall, there was no statistically significant difference in first-attempt success rate (OR = 1.92; 95% CI: 0.85, 4.32; I² = 0%; P = 0.44). There was no clinically significant difference in time to insertion (WMD = −15.80 seconds; 95% CI: −25.30, − 6.31 seconds; I² = 100%; P = 0.001). Similarly, there was no difference in any adverse event rate except sore throat, which was reduced with the use of an SGA (OR = 0.16; 95% CI: 0.08, 0.32; I² = 53%; P < 0.001). On the basis of current evidence, it is inconclusive whether SGAs are equivalent to ETT for elective CD. Further studies are required before the use of an SGA as the first-line airway device for an elective CD can be recommended. A review by Metodiev (2023, [C-EO])[62] concluded that when a supraglottic airway device is in position and working well, it should continue to be used for oxygenation.

Second-generation supraglottic airways provide better airway seal and, with proper placement, provide near-complete isolation of the gastric and respiratory channels. In addition, 2^nd generation supraglottic airways could also serve as a conduit for performing fibrescope-guided intubation once they have been placed as a rescue device. The choices of 2^nd generation supraglottic airways available through which this step can be performed have been described by Wong (2020 [C-EO]).[63] ‘Supraglottic airway-guided fibreoptic bronchoscopic intubation’ is referred to as SAGFBI. For a given size of supraglottic airway device (SAD) (size #3 taken as reference), some SADs have wide enough ventilation ports (‘wide SAD’) to allow insertion of a standard tracheal tube for the direct SAGFBI method. “Wide SADs” include the Classic LMA (cLMA), i-Gel, Ambu AuraGain, Air-Q, and LMA Protector. As for other size # 3 SADs such as the ProSeal LMA and LMA Supreme, the ventilation ports are too narrow (‘narrow SAD’) for a standard tracheal tube to be inserted. As narrow SADs preclude direct SAGFBI, indirect methods (such as the use of an Aintree Intubation Catheter) need to be chosen. As direct SAGFBI is preferred, the authors recommend the use of a wide 2^nd-generation SAD. If 6.0 mm ID tracheal tubes are to be used for SAGFBI, microlaryngeal tubes are preferred as they are longer with adult size cuffs and cuff inflation at the level of the vocal cords can be avoided.

In summary, 2^nd generation supraglottic airways can be considered as safe “rescue” options when tracheal intubation fails during rapid sequence induction and intubation for caesarean deliveries. In the absence of high-quality evidence for rescue after failed intubation, a Delphi Survey was conducted to obtain Expert Consensus.

Use of 2^nd generation supraglottic airways as a “primary airway device” for caesarean delivery is not supported by current literature because their “safety about prevention of aspiration” has not been adequately powered as reported in randomised controlled trials.

If fibreoptic bronchoscopic intubation is to be performed through a 2^nd generation supraglottic airway that has served the purpose of airway rescue, wide SADs such as the i-Gel, Ambu AuraGain, Air-Q, and LMA Protector are preferred choices. Narrow SADs such as ProSeal LMA and LMA Supreme need tracheal intubation to be performed using indirect methods.

Best Practice Statement: Supraglottic airway is not recommended for use as a planned primary airway device for elective caesarean delivery.

Strength of Recommendation: Class 3 Benefit = Risk, Level of Evidence: B-R

Delphi Survey results [Addendum 1]

Delphi Survey Question: Following a failed intubation, when satisfactory ventilation is achieved through a properly placed 2^nd generation SGA, should general anaesthesia be continued to complete the caesarean delivery if fetal and/or maternal status is compromised?

Expert Clinical Consensus: Following a failed intubation, when satisfactory ventilation is achieved through a properly placed 2^nd generation SGA, general anaesthesia should be continued to complete the caesarean delivery if fetal and/or maternal status is compromised.

Research Question 4

Does application of cricoid force prevent regurgitation and aspiration in parturients undergoing caesarean delivery under general anaesthesia? [Appendix 3][85,86,87,88,89,90]

Following a full text review of 30 articles by KJ and SMA, six articles were shortlisted, of which three systematic reviews and meta-analysis, two non-inferiority double-blind RCTs, and one observational study were relevant to our question and were analysed in detail. Most studies were conducted on non-pregnant patients, except one (an observational study), which was conducted on pregnant patients. The authors of all the studies were of the opinion that cricoid force should be used during RSII. However, the studies did not demonstrate any significant difference in the incidence of pulmonary aspiration after application of cricoid force. On the other hand, the application of cricoid force showed an increase in intubation time.

Birenbaum et al. (2018, Level B-R)[86] showed that pulmonary aspiration occurred in 10 patients (0.6%) in the Sellick manoeuvre group and in 9 patients (0.5%) in the sham group. They failed to demonstrate the non-inferiority (δ = 50%) of a sham procedure as compared with the cricoid pressure in preventing pulmonary aspiration in non-pregnant patients undergoing RSII. In addition, Cormack and Lehane grade was significantly worse and intubation time was longer (Intubation time >30 seconds, 47% vs 40%; P <0.001), suggesting an increased difficulty of tracheal intubation in the Sellick manoeuvre group. Similarly, White et al. (2020, Level B-R)[87] conducted a systematic review and meta-analysis on cricoid pressure during intubation and found significantly decreased first attempt success rate, prolonged intubation time, and worsened laryngoscopic views with cricoid pressure. Further, they failed to show any increase in protection from aspiration with cricoid pressure. Contrarily, Hung et al. (2021, Level B-R),[88] in their systematic review and meta-analysis, found that application of cricoid pressure had no negative impact on the successful first-attempt intubation rate or laryngoscopic view. However, cricoid pressure may slightly prolong intubation time and increase the risk of post-operative hoarseness.

Similarly, Gupta et al. (2024, Level B-R)[89] found that para-laryngeal pressure was non-inferior to CP in occluding the oesophagus in parturients undergoing caesarean delivery with no significant deterioration in intubation parameters. There was no significant difference in the POGO score (P = 0.818), time to intubation (P = 0.55), or intubation attempts (P = 0.99). Tessarolo et al. (2022, Level B-R)[90] conducted a systematic review on the effectiveness and risks of cricoid pressure (CP) during rapid sequence induction for endotracheal intubation. They found that CP did not have a significant effect on first pass success rate (84.7% FPS if CP used vs 83.3% FPS without CP, P = 0.7460) and also and did not prevent aspiration in the emergency setting. Fenton and Reynolds (2009, Level B-NR)[85] conducted an observational study of the use of cricoid pressure and maternal outcome and could not show any protection from aspiration with cricoid pressure.

Cricoid force may be considered for use during RSII in pregnant patients as it does not reduce the first pass success rate and laryngoscopy view, though it might increase the intubation time and does not have significant positive role in prevention of gastric aspiration.

Best Practice Statement: Application of cricoid force may be considered during general anaesthesia for caesarean delivery.

Strength of Recommendation: Class 2b, Level of Evidence: B-NR.

Research Question 5

Does high-flow nasal oxygen during preoxygenation and continued during apnoea versus face mask preoxygenation reduce peri-induction desaturation in parturients undergoing caesarean delivery under general anaesthesia? [Appendix 4][13,32,91,92,93,94,95,96]

In this review done by AG and SRS, nine articles were included in the final review. Several studies have evaluated whether apnoeic oxygenation, particularly with high-flow nasal oxygen (HFNO), should replace face-mask ventilation in parturients. The evidence is mixed in support of HFNO benefits over traditional face mask preoxygenation.

Two randomised controlled trials comparing HFNO preoxygenation plus apnoeic oxygenation versus standard face mask preoxygenation (no apnoeic oxygenation) using extension of apnoea time as the endpoint reported improved outcomes as HFNO was used for apnoeic oxygenation also [Osman (2021) Level B-R, Zhou S (2021) Level B-R].[13,94] A case report (Hengen M 2017, C-LD)[91] of parturient with pneumonia and heart failure also reported benefits of HFNO. These non-randomised trials/observational studies and dose finding studies, which used EtO2 as the endpoint for preoxygenation, found HFNO to be less effective in achieving preoxygenation in parturients undergoing caesarean delivery [Tan (2024) Level B-NR, Au (2020) Level B-NR, Patel (2020) Level C-LD].[32,95,96] Similarly Shippam (2019, B-NR)[92] and Al-Sulttan S (2021, B-NR)[93] reported inferior EtO₂.

In summary, HFNO used as preoxygenation and continued during apnoea as apnoeic oxygenation can extend the safe apnoea time compared to the traditional technique of face mask preoxygenation without any apnoeic oxygenation.

Best Practice Statement: High-flow nasal oxygen for preoxygenation followed by apnoeic oxygenation may be considered to reduce peri-induction desaturation in parturients undergoing caesarean delivery under general anaesthesia.

Strength of Recommendation: Class 2b, Level of Evidence: B-NR

Research Question 6

Compared to low-flow nasal oxygen (LFNO), does apnoeic oxygenation using high-flow nasal oxygen (HFNO) provide better oxygenation and reduce the risk of hypoxaemia during the apnoeic period in parturients undergoing caesarean delivery under general anaesthesia? [Appendix 5][7,13,14,32,35,97,98]

To determine the role of apnoeic oxygenation in parturients undergoing caesarean delivery under general anaesthesia comparing HFNO and LFNO, the review was done by SRS and AG. A total of 7 articles were included in the final summary. Evidence of use of HFNO for apnoeic oxygenation versus LFNO is emerging and mixed, lacking high-quality evidence. Only one randomised control trial (Osman 2021, Level B-R)[13] comparing HFNO preoxygenation plus apnoeic oxygenation against face mask preoxygenation and LFNO (6 LPM) apnoeic oxygenation indicated superiority of HFNO. Expert opinion and guidelines [Ramkumar (2016) Level C-EO; Murphy (2021) Level C-EO][7,98] suggested LFNO as being an effective technique and adaptability for routine practice as it can be easily accommodated along with the face mask preoxygenation. HFNO as a preoxygenation technique with EtO₂ as the endpoint has not been proven to be superior to face mask preoxygenation [Appendix 4]. Face mask preoxygenation is still the technique most commonly applied, and LFNO can be easily adapted with it. Currently, all studies have compared HFNO preoxygenation and apnoeic oxygenation against face mask preoxygenation and LFNO as an apnoeic oxygenation technique, and results are encouraging [Osman (2021) Level B-R][13] but insufficient. With the recent introduction of the HFNO cannula, Optiflow Switch™ Nasal Interface, the use of HFNO purely for the purpose of apnoeic oxygenation with face mask preoxygenation will become feasible and may become the standard of care. Use of apnoeic oxygenation techniques (HFNO or LFNO) improves safety and must be used during induction of anaesthesia in parturients undergoing general anaesthesia [Wong (2022) Level C-EO, Ramkumar (2016) Level C-EO].[7,35] Due to limited quality data in parturients undergoing caesarean delivery, it is not well established that HFNO is superior to LFNO for apnoeic oxygenation in increasing the duration of safe apnoea.

Best Practice Statement: In parturients undergoing caesarean delivery under general anaesthesia, either HFNO or LFNO may be considered for apnoeic oxygenation.

Strength of Recommendation: Class 2b, Level of Evidence: C-EO

Research Question 7

What should be the antral volume measured by gastric ultrasound to minimise the risk of aspiration in a full-term parturient undergoing caesarean delivery under GA? [Appendix 6][22,25,26,27,28,99,100,101,102,103,104,105,106,107,108]

The review was done by PK and AP. A total of 14 citations were included in the final summary. Based on a comprehensive review of available literature, the quantitative criteria most commonly used to define a “full stomach” in pregnant women using gastric sonography are a gastric fluid volume (GFV) of ≥1.5 mL/kg. Multiple prospective studies and expert opinions support this threshold. Harnett et al. (B-NR, 2024)[26] re-affirm this cut-off as a standard benchmark, stating that gastric volumes exceeding 1.5 mL/kg are associated with an increased risk of aspiration, even in some non-labouring women who adhered to fasting guidelines. Similarly, Van de Putte et al. (B-NR, 2019)[103] demonstrated that the 95^th percentile of gastric volume in fasting, non-labouring term pregnant patients is approximately 1.4 mL/kg, reinforcing the validity of the 1.5 mL/kg threshold as a conservative safety limit.

Several studies have explored the association between the cross-sectional area (CSA) of the gastric antrum and estimated gastric volume. Arzola et al. (B-R,2018)[27] identified a CSA cut-off value of 9.6 cm² in the right lateral semi-recumbent position that reliably predicted a gastric volume of ≥1.5 mL/kg, with an area under the curve (AUC) of 0.82. Perlas et al. (C-EO, 2018)[106] and Van de Putte[107] supported this finding, noting that CSA values between 9 and 10 cm² typically indicate gastric volumes above the 1.5 mL/kg mark. Other researchers, such as Zieleskiewicz (B-NR,2020),[28] proposed specific CSA cut-offs depending on patient position, with a value of 608 mm² in the supine position correlating with gastric volumes over 1.5 mL/kg.

In labouring women, the incidence of “risk stomach”, defined by gastric volume ≥1.5 mL/kg or higher antral CSA, appears to be significantly elevated. Chang et al. (B-NR, 2022)[101] and Desgranges et al. (B-NR, 2022)[100] observed that parturients, particularly those under liberal oral intake during labour, often exceeded this threshold. This underscores the variability of gastric emptying during labour and supports the utility of bedside ultrasound to guide anaesthetic risk stratification in these cases. Moreover, even after adherence to standard fasting protocols, a considerable proportion of non-labouring parturients (up to 37.5% in the study by Hakak et al.[22]) had residual volumes >1.5 mL/kg, highlighting that fasting duration alone may not ensure an empty stomach.

Summary of High-Risk Indicators

Features associated with high aspiration risk in pregnant women include:

• Presence of thick fluid or solid contents

• CSA >608 mm² in the supine/semirecumbent position

• CSA >505 mm² with visible fluid

• CSA >960 mm² in the right lateral semirecumbent position

In summary, the threshold of 1.5 mL/kg remains the most widely accepted quantitative criterion for defining a full stomach in pregnant women using gastric sonography. It is associated with a significantly increased risk of aspiration, and volumes below this cut-off are generally considered to be safe. However, due to inter-individual variability and the physiological changes of pregnancy and labour, point-of-care gastric ultrasound plays a critical role in individual risk assessment, particularly in emergent or semi-elective settings such as caesarean delivery.

Best Practice Statement: An antral volume exceeding 1.5 mL/kg, assessed using gastric ultrasound in the right lateral decubitus position, may indicate a higher aspiration risk in full-term parturients undergoing caesarean delivery under general anaesthesia.

Strength of Recommendation: Class 2b, Level of Evidence: B-NR

Research Question 8

How long should a parturient be kept fasting before anaesthesia for caesarean delivery? [Appendix 7][22,23,24,26,101,102,103,105,109,110,111]

Fasting for solids in pregnant women

Several studies have investigated the adequacy of preoperative fasting for solids in pregnant women. Hakak et al. (2018, B-NR),[22] in a prospective observational study, found that while no solid food was visible in the gastric antrum after 6 hours of fasting, a considerable number of pregnant women still had residual gastric fluid volumes potentially associated with aspiration risk. This suggests that while a 6-hour fasting may be sufficient to clear solids, it does not eliminate aspiration risk from fluids. In an RCT conducted by Bouvet et al. (2022, B-R),[109,110] it was found that gastric emptying after a light meal is delayed in parturients; however, the presence of labour analgesia may facilitate the process, potentially offering some protective benefit.

In a comparative cross-sectional study, Chang et al. (2022, B-NR)[101] demonstrated that labouring women under liberal oral intake had a higher prevalence of “risk stomach” compared to non-labouring women. These findings collectively support maintaining a minimum fasting period of 6 hours for solids in pregnant women, especially those in labour. Risk factors such as obesity, advanced labour,[24] and liberal feeding practices can contribute to increased residual gastric content. Gastric ultrasound emerges as a useful point-of-care tool to evaluate individual aspiration risk even in those who have adhered to standard fasting protocols.

Fasting for liquids in pregnant women

Regarding liquids, the evidence supports a more liberal approach. A randomised non-inferiority trial conducted by Nascimento et al. (2019, B-R)[23] found that 450 mL of maltodextrin was cleared from the stomach within 90 minutes, significantly faster than coffee with milk or orange juice. Irwin et al. (2020, B-R)[24] similarly showed that a combination of tea with milk and water (500 mL total) produced gastric emptying profiles comparable to plain water, with complete clearance observed within 2 hours. Popivanov et al. (2020, B-NR)[105] supported these findings, demonstrating that 400 mL of a carbohydrate drink was safely cleared in under 2 hours.

Harnett et al. (2024, B-NR)[26] tested a “sip till send” protocol and found no significant difference in gastric volume between women who stopped clear fluids at midnight and those who sipped water until call to the operating room, suggesting that clear liquids up to 1 hour before caesarean delivery may be safe in selected parturients. Ng et al. (2024, B-R)[111] further reinforced this approach by showing in a randomised trial that unrestricted water intake up to operating room dispatch significantly reduced perioperative vomiting and was strongly preferred by parturients, without increasing aspiration risk.

Best Practice Statement: For elective caesarean delivery, parturients may consume clear fluids up to 2 hours and a light meal up to 6 hours before anaesthesia.

Strength of Recommendation: Class 2b, Level of Evidence: B-NR

Research Question 9

If face mask ventilation is successful in a parturient undergoing caesarean delivery under general anaesthesia, can it be considered safe and feasible to continue the anaesthetic and deliver the baby without proceeding to tracheal intubation? [Appendix 8][7,84,112,113,114,115,116]

A total of 123 articles were reviewed by AS and SMA, and 6 articles were finally included. The majority of the evidence was of low quality in the form of review, guidelines, or retrospective analysis. Šklebar I (2023, C-LD),[112] Asai T (2015, C-LD),[113] and Mushambi MC (2016, C-LD)[114] discussed obstetric airway management, noting face mask ventilation as an option in failed intubation. Though all of them mentioned face mask ventilation, continuing with the surgery solely under face mask ventilation is not explicitly addressed. Ezri T (2001, C-LD),[115] explicitly supported its use to manage difficult airways. Tao W (2012, B-NR)[116] reported rare cases requiring face mask ventilation and highlighted its effectiveness when used.

Mushambi MC (2015, C-EO)[84] and Ramkumar V (2016, C-EO)[7] provided structured guidelines, recommending controlled face mask ventilation after failed intubation and supraglottic airway device failure, with continuation of surgery in situations posing immediate threat to the mother or fetus.

While face mask ventilation is acknowledged in difficult obstetric airway scenarios, the absence of high-level evidence in the form of randomised controlled trials necessitated a Delphi survey to establish expert consensus and formal recommendations. Three questions were designed to get expert opinion in situation of successful facemask ventilation after failed intubation and SGA ventilation. The patient could be apnoeic or have adequate spontaneous breathing or breathing may have started but is inadequate.

Clinical Consensus Statement

1. The obstetrician–anaesthesiologist team should proceed to deliver the baby with continued application of cricoid force when tracheal intubation and ventilation using a 2^nd generation SGA has failed, spontaneous breathing has NOT returned, face-mask ventilation is possible, and there is immediate threat to the life of the fetus or mother.

2. The obstetrician–anaesthesiologist team should proceed to deliver the baby with continued application of cricoid force when tracheal intubation and ventilation using a 2^nd generation SGA has failed, adequate spontaneous breathing has returned, it is possible to maintain oxygenation and anaesthesia with the face mask, and there is immediate threat to the life of the fetus or mother.

3. The obstetrician–anaesthesiologist team should administer an additional dose of muscle relaxant to facilitate ventilation and proceed to deliver the baby with continued application of cricoid force when tracheal intubation and ventilation using a 2^nd generation SGA has failed, spontaneous breathing has returned but is inadequate for maintaining effective oxygenation and anaesthesia with a face mask, and there is immediate threat to the life of the fetus or mother.

Research Question 10

In a parturient undergoing caesarean delivery under general anesthesia with rapid sequence induction, is it safe to allow gentle face mask ventilation and release cricoid force if difficulty with ventilation or intubation is encountered? [Appendix 9][7,32,37,38,48,76,82,113,114,117,118,119,120]

The review was done by SMA and KJ. A total of 219 articles were reviewed to include 13 in the final summary. Rapid sequence induction is considered standard of care in parturients undergoing caesarean delivery under general anaesthesia. Modified rapid sequence induction, particularly release of cricoid force if difficulty with ventilation or laryngoscopy occurs and there is gentle face mask ventilation to improve oxygenation, is practised by many anaesthesiologists and reported by many articles. The level of evidence supporting modified RSI is low [Asai T (2015, C-EO),[113] Banks A (2007, C-EO),[117] Choi SU (2022, C-EO),[76] Fleming N (2019, C-EO),[119] Meniolle F (2018, C-EO),[120] Mushambi MC (2016, C-EO),[114] Patel S (2020, C-EO),[32] Ramkumar V (2016, C-EO),[7] Sharp LM (2009, C-EO),[38] Desai N (2018, C-LD)[118]], except one meta-analysis by Neilipovitz N (2007, B-R),[37] which examined RSI for all indications (obstetrics not clear).

Neilipovitz N et al. (2007, B-R)[37] supports the use of cricoid force despite the lower level of evidence for efficacy and also suggests to release the cricoid force if it hinders airway management. They also support gentle face mask ventilation at a circuit pressure less than 20 cm H₂O. Gentle face mask ventilation prolongs the safe apnoea time without increasing the aspiration risk particularly when cricoid force is applied correctly. The only caveat here is that this meta-analysis was not for parturients only. Mushambi MC (2016, C-EO)[114] and Ramkumar V (2016, C-EO)[7] support use of cricoid force and release of cricoid force as well as gentle face mask ventilation during apnoea. Patel S (2020, C-EO)[32] supports application of cricoid force at 30 N after induction but may be released if difficult intubation/ventilation occurs, and also supports gentle FMV (<20 cm H₂O) to extend safe apnoea time. The optimal application of cricoid force involves an initial force of 10 N in awake patients, increasing to 30 N after loss of consciousness [Choi SU (2022, C-EO),[76] Fleming N (2019, C-EO),[119] Mushambi MC (2016, C-EO),[114] Patel S (2020, C-EO)].[32] Sharp LM (2009, C-EO)[38] suggest cricoid force may not be necessary in fasting obstetrics patients. Survey data (Desai N (2018, C-LD)[118] indicate that 49% of anesthetists already use gentle mask ventilation in obstetric RSI.

Due to the limited high-quality evidence, Best Practice Statements needed be re-evaluated through a Delphi survey, engaging obstetric anaesthesiology experts to establish consensus on use of cricoid force, its optimal release strategy, and the role of gentle mask ventilation in obstetric RSI.

Delphi Survey results: [Addendum 1]

Delphi Questions

1. During rapid sequence induction, should face mask ventilation be used during the apnoeic period prior to intubation in parturients undergoing caesarean delivery who are at a high risk of desaturation?

2. If application of cricoid force (Sellick’s manoeuvre) is causing difficulty for face mask ventilation, cricoid force should be removed completely.

3. If application of cricoid force (Sellick’s manoeuvre) is causing difficulty in placement of a SGA, cricoid force should be removed completely.

4. If application of cricoid force (Sellick’s manoeuvre) is causing difficulty for tracheal intubation because of poor laryngeal view, cricoid force should be removed completely.

Expert Consensus Statements

1. During rapid sequence induction, gentle face mask ventilation (with peak pressures limited to 20 cm H₂O) should be used during the apnoeic period prior to intubation in parturients undergoing caesarean delivery who are at a high risk of desaturation.

2. Cricoid force (Sellick’s manoeuvre) should be removed completely if it is causing difficulty for face mask ventilation.

3. Cricoid force (Sellick’s manoeuvre) should be removed completely if is causing difficulty in placement of an SGA.

4. Cricoid force (Sellick’s manoeuvre) should be removed completely if it is causing difficulty for tracheal intubation because of a poor laryngeal view.

Research Question 11

Does the availability of sugammadex support the preferential use of rocuronium over succinylcholine in term parturients undergoing caesarean delivery under general anaesthesia? [Appendix 10][7,36,38,50,82,84,114,118,121,122,123,124,125]

A total of 65 articles were reviewed, with 13 selected by SRS and AG. Rocuronium (1.2 mg/kg) has been explored as an alternative to succinylcholine (1 to 1.5 mg/kg) for rapid sequence induction (RSI) in caesarean deliveries, particularly when succinylcholine is contraindicated. Studies such as the ones by Stourac P (2016, B-R)[121] and Abu-Halaweh SA (2007, B-R)[122] have demonstrated that rocuronium, when used at high doses, provides comparable intubation conditions to succinylcholine. However, Kosinova M (2017, B-R)[36] reported a trend towards lower 1-minute Apgar scores in neonates exposed to rocuronium, though these scores equalised at 5 and 10 minutes, suggesting a transient effect rather than sustained neonatal compromise.

Neonatal outcomes remain a point of concern, particularly regarding umbilical cord gases and early Apgar scores. A review by Mushambi MC (2016, C-LD)[114] found that rocuronium, when reversed with sugammadex, largely mitigates concerns regarding prolonged neonatal neuromuscular blockade. Similarly, Devroe S (2015, C-LD)[50] reported that using rocuronium with sugammadex ensures a rapid onset and reversal without significant neonatal complications. However, despite these findings, a survey by Desai N (2018, C-LD)[118] indicated that 92% of anaesthetists still preferred succinylcholine, citing cost concerns, rapid spontaneous recovery, and the potential for transient neonatal depression with rocuronium.

The use of sugammadex (16 mg/kg) for rapid reversal of rocuronium-induced neuromuscular blockade has been extensively studied. Mushambi MC (2016, C-LD)[114] found that rocuronium–sugammadex reversal resulted in a faster return to spontaneous breathing than succinylcholine, making it a viable alternative. Similarly, Sharp LM (2009, C-LD)[38] concluded that sugammadex allows for safe and effective reversal while avoiding succinylcholine-related risks such as hyperkalaemia, myalgia, and malignant hyperthermia. However, the NAP6 analysis by Odor PM (2021, B-NR)[123] showed that while the use of rocuronium in obstetric anaesthesia has increased to 11.8%, succinylcholine remains the preferred agent due to cost and familiarity, and the risk of anaphylaxis with sugammadex.

Current guidelines, such as those from Ramkumar V (2016, C-EO),[7] continue to recommend succinylcholine (1.5 mg/kg) as the first-line agent for RSII, with rocuronium (1.2 mg/kg) plus sugammadex being a second-line option when succinylcholine is contraindicated. Cost constraints and the need for pre-calculated sugammadex dosing in emergency settings remain barriers to routine adoption (Mushambi M (2015, C-EO).[84]

Due to lack of conclusive evidence, a Delphi survey of experts was performed to identify whether use of rocuronium for caesarean delivery under general anaesthesia could be recommended.

Delphi Survey Results: [Addendum 1]

Delphi Survey Question: Should rocuronium be considered over succinylcholine for caesarean delivery at term if an adequate dose (16 mg/kg) of sugammadex is available to reverse neuromuscular blockade immediately after an intubating dose of rocuronium is administered?

Expert Consensus Statement: Rocuronium should be considered over succinylcholine for caesarean delivery at term if an adequate dose (16 mg/kg) of sugammadex is available to reverse neuromuscular blockade immediately after an intubating dose of rocuronium is administered.

SUMMARY

With central neuraxial anaesthesia becoming the preferred approach for caesarean deliveries, general anaesthesia is being used less frequently, that too for specific indications. Parturients often have challenging airways. Failure to intubate can therefore have serious consequences for both mother and baby.

In keeping with current practice, the 2025 Obstetric Guidelines recommend rapid sequence induction and intubation (RSII) for parturients requiring general anaesthesia for caesarean delivery. If the initial intubation attempt fails, the anaesthesia team should “Call for help for difficult airway” (Code D) and prioritise providing oxygen to maintain haemoglobin oxygen saturation (SpO₂) above 95%. While awaiting help, a more experienced operator from the anaesthesia team may re-attempt tracheal intubation after re-optimising position and considering alternate airway devices. The primary team can opt for a 2^nd generation supraglottic airway (SGA) device as rescue or continue the anaesthetic using a face mask (FM). Maintaining oxygenation throughout the period while attempting to establish a definitive airway should be given top priority. If satisfactory oxygenation is achieved with either a 2^nd generation SGA device or FM, and both maternal and fetal conditions are reassuring – awaken the mother. If maternal and fetal conditions are non-reassuring and the SGA device is sited with a leak, continue with SGA device until baby delivery and then consider FOB-guided intubation if equipment and expertise are available. On the contrary, if SGA device is well sited, the entire anaesthetic may be conducted with the SGA device unless the airway deteriorates or the maternal condition warrants.

If FM ventilation is achieved and maternal and fetal conditions are non-reassuring, the anaesthesiologist has one of three options. If adequate spontaneous breathing has returned or the patient remains apnoeic, the anaesthetic may be continued using FM with continued application of cricoid force. If spontaneous breathing has returned but is inadequate, additional neuromuscular blocking agents should be administered and anaesthetic continued using FM with continued application of cricoid force.

If following failed tracheal intubaton, the anaesthesiologist cannot maintain a satisfactory airway (as evidenced by capnograph trace and adequate chest rise) with a 2^nd generation SGA device or FM, declare “complete ventilation failure” and prepare to perform emergency surgical cricothyroidotomy. Should the clinical situation deteriorate at any time resulting in maternal cardiac arrest, proceed to “resuscitative hysterotomy” to improve chances of saving the mother and baby. Post-resuscitation care should continue in the intensive care unit and steps taken to return the parturient to normalcy and discharge.

Obstetric anaesthesiologists must bear in mind that parturients may have a physiologically difficult airway in addition to anatomical reasons for airway difficulty. Specific steps to deal with associated pathophysiological changes while the airway is being secured assume additional importance during airway management. Once a difficult airway is encountered, an “Airway Alert Card” (describing the nature of airway difficulty faced and the steps taken to overcome it) needs to be given to the parturient and her responsible relatives to avoid similar life-threatening situations in future.

Presentation at Conferences/CMEs and Abstract Publication:

Nil

Study data availability

De-identified data may be requested with reasonable justification from the authors (email to the corresponding author) and shall be shared upon request.

Disclosure of use of artificial intelligence (AI)-assistive or generative tools

AI tools or language models (LLMs) have not been utilised in the manuscript, except that software has been used for grammar corrections and references.

Declaration of use of permitted tools

The tables and figures are self-made and not copyrighted.

Authors’ contributions

VR, KJ, PK, APS, SRS, MGB, AP, SMA and AG as Core Committee Members, were involved in the concept and design of the guidelines, contributed to the literature search, manuscript drafting, editing and critical review, and approved the final version. SNM, RG, JRD, JVD and SD as Experts provided specialised inputs in the development of recommendations, contributed to the refinement of content, reviewed the manuscript critically for accuracy and relevance, and approved the final version. All authors agree to be accountable for all aspects of the work in ensuring the accuracy and integrity of the manuscript.

Supplementary material

This article has supplementary material and can be accessed at this link. Supplementary Material at http://links.lww.com/IJOA/A44.

Conflicts of interest

Dr Amit Shah - inventor of Patwashahi videolaryngoscope (non-commercial), designer of HFNO device HuFlo2. Dr Pankaj Kundra, Dr Rakesh Garg, Dr Jeson R Doctor, Dr Sheila Nainan Myatra and Dr Syed Moied Ahmed, who are co-authors of this manuscript, are editors of this journal. They were not involved in the decision-making process, and an independent editor handled this manuscript. Other authors declare that they have no conflicts of interest.

Appendices

APPENDIX 1

Research Question 1: Does videolaryngoscopy improve the success rate of intubation compared to direct laryngoscopy in parturients undergoing Caesarean delivery under general anaesthesia?

• Population - Parturients undergoing Caesarean delivery under general anaesthesia

• Intervention - Videolaryngoscopy

• Control / Comparison - Direct laryngoscopy

• Outcome - Successful tracheal intubation

Supplementary Table 1a.

Concept table for Research Question: Does videolaryngoscopy improve the success rate of intubation compared to direct laryngoscopy in parturients undergoing Caesarean delivery under general anaesthesia?

Research Question	Concept 1	Concept 2	Concept 3	Concept 4	Concept 5	Concept 6	Concept 7	Concept 8
Key concepts	Pregnancy	Term pregnancy	Caesarean	Direct laryngoscopy	GA	Videolaryngoscopy	Videolayngoscope C-MAC, GlideScope, King Vision	Macintosh type
Free text terms/natural language terms (synonyms, UK/US terminology, medical/ laymen's terms, acronyms/ abbreviations, drug brands, more narrow search terms) Consider: phrase searching, proximity operators, truncation, wildcards, field qualification (e.g. textword)	pregnancies; pregnant; normal pregnancy; pregnancy normal; pregnan*	Parturie nt Parturiti ons last trimester. Pregnancy Trimester, Third Third Pregnancy Trimester Third Pregnancy Trimesters Pregnancy, Third Trimester Pregnanc	Cesarean surgery; emergency Cesarean delivery; Elective cesarean delivery; Caes arean surgery; emergency Caesarean delivery; Elective caesarean delivery; obstetric surgeries; obstetric surgery Cesarean Section/ methods* Caesarean delivery Cesarean	“direct laryngoscopy “[All Fields] Direct laryngoscopy Direct laryngoscope Traditional laryngoscopy Conventional laryngoscopy	Anesthesia, General/ methods* Anesthesi a* Anesthesia, Obstetrical/ methods* Anesthesia, Obstetric al* Anesthesias, General General Anesthesi General Anaesthesiaas	“videolaryngos copy” [All Fields] Videolaryngos copy Video laryngoscopy Video-assisted laryngoscopy Video Assisted Techniques and Procedures Video Assisted Techniques Techniques, Video Assisted Technique, Video Assisted Video Assisted Technique Recordings, Video Recording, Video Video	“C-Mac” “glidescop e”[All Fields] “king vision”[Al l Fields] (mcgrath [tiab]) NOT (mcgrath [auth]) ((Macinto sh [tiab]) OR	(“Macintosh laryngoscope “)) NOT (Macintosh [auth]) “hyperangul ated”[All Fields] **Nothing specific is coming for the Channel type of VL
Controlled vocabulary terms/Subject terms (MeSH terms, Emtree terms) Consider: explode, major headings,	Pregnancy	“Term Birth”[Mesh] “Pregnancy Trimester, Third”[ Mesh]	Cesarean Section “Cesarean Section” [Mesh] “Cesarean Section” [Mesh: NoExp]	“Laryngosco py”[MeSH] “Laryngosco pes”[Mesh]	“Anesthetics, General” [Mesh] “Anesthe sia”[Mesh] “Anesthesia,	“VideoAssisted Techniques and Procedures”[ Mesh] “Video Recording”[Mesh]

Search string

PubMed: 101 results

(((“pregnancies”[Title/Abstract] OR “pregnant”[Title/Abstract] OR “normal pregnancy” [Title/Abstract] OR “pregnancy normal” [Title/Abstract] OR “pregnan”[Title/Abstract] OR “pregnancy”[MeSH Terms]) AND 2000/01/01:2024/12/31[Date - Publication]) OR ((“Parturient”[Title/Abstract] OR “Parturitions”[Title/Abstract] OR “Last Trimester” [Title/Abstract] OR “pregnancy trimester third” [Title/Abstract] OR “Third Pregnancy Trimester”[Title/Abstract] OR “Third Pregnancy Trimesters”[Title/Abstract] OR “pregnancy third trimester”[Title/ Abstract] OR “pregnancies third trimester”[Title/Abstract] OR “Third Trimester Pregnancies”[Title/Abstract] OR “Third Trimester Pregnancy”[Title/Abstract] OR “trimester third”[Title/Abstract] OR “Third Trimester”[Title/ Abstract] OR “Third Trimesters”[Title/Abstract] OR “trimesters third”[Title/Abstract] OR “Last Trimester”[Title/ Abstract] OR “Last Trimesters”[Title/Abstract] OR “trimester last”[Title/Abstract] OR “Term Birth”[MeSH Terms] OR “pregnancy trimester, third”[MeSH Terms]) AND 2000/01/01:2024/12/31[Date - Publication]) OR ((“Cesarean surgery”[Title/Abstract] OR “emergency Cesarean delivery”[Title/Abstract] OR “Elective cesarean delivery”[Title/ Abstract] OR “Caesarean surgery”[Title/Abstract] OR “emergency Caesarean delivery”[Title/Abstract] OR “Elective caesarean delivery”[Title/Abstract] OR “obstetric surgeries”[Title/Abstract] OR “obstetric surgery”[Title/Abstract] OR “cesarean section methods”[Title/Abstract] OR “Caesarean delivery”[Title/Abstract] OR “Cesarean Sections”[Title/ Abstract] OR ‘Abdominal Delivery”[Title/Abstract] OR “c sections ob”[Title/Abstract] OR “Caesarean Section”[Title/ Abstract] OR “Caesarean Sections”[Title/Abstract] OR “delivery abdominal”[Title/Abstract] OR ‘Abdominal Deliveries” [Title/Abstract] OR “deliveries abdominal”[Title/Abstract] OR “Postcesarean Section”[Title/Abstract] OR “deliveries obstetric”[Title/Abstract] OR “Obstetric Deliveries”[Title/Abstract] OR “Obstetric Delivery”[Title/ Abstract] OR “Cesarean Section”[MeSH Terms] OR “Cesarean Section”[MeSH Terms:noexp] OR “cesarean section, repeat”[MeSH Terms:noexp]) AND 2000/01/01:2024/12/31[Date - Publication])) AND ((“anesthesia general methods”[Title/Abstract] OR “anesthesia”[Title/Abstract] OR “anesthesia obstetrical”[Title/Abstract] OR “General Anesthesia”[Title/Abstract] OR “General Anesthesias”[Title/Abstract] OR “anesthetics, general”[MeSH Terms] OR ‘Anesthesia”[MeSH Terms] OR “anesthesia, obstetrical”[MeSH Terms]) AND 2000/01/01:2025/12/31[Date - Publication])) AND ((“Directlaryngoscopy”[All Fields] OR “Direct laryngoscopy”[Title/Abstract] OR “Direct laryngoscope”[Title/Abstract] OR “Traditional laryngoscopy”[Title/Abstract] OR “Conventional laryngoscopy”[Title/ Abstract] OR “Laryngoscopy”[MeSH Terms] OR “Laryngoscopes”[MeSH Terms]))**

Scopus : 336 results

((TITLE-ABS-KEY("labor" OR "labored" OR "laborer" OR "laborers" OR "laboring" OR "labors" OR "labour" OR "work" OR "labor, obstetric" OR "obstetric labor" OR "laboured" OR "labourer" OR "labourers" OR "labouring" OR "labours" OR "parturient" OR "parturients" OR "parturition" OR "delivery, obstetric" OR "obstetric delivery" OR "parturitions" OR "parturitional" OR "birth" OR "birthed" OR "birthing" OR "childbirth" OR "pregnancy" OR "pregnancies" OR "pregnancy s" OR "Term Birth" OR "Last Trimester") AND PUBYEAR > 1999 AND PUBYEAR < 2025) OR (TITLE-ABS-KEY("pregnancy trimester, third" OR "trimester, third" OR "Third Pregnancy Trimester" OR "Third Pregnancy Trimesters" OR "pregnancy third trimester" OR "pregnancies third trimester" OR "Third Trimester Pregnancies" OR "Third Trimester Pregnancy" OR "trimester third" OR "Third Trimester" OR "Third Trimesters" OR "trimesters third" OR "Last Trimester" OR "Last Trimesters" OR "trimester last" OR "pregnancy trimesters" OR "trimesters") AND PUBYEAR > 1999 AND PUBYEAR < 2025) OR (TITLE-ABS-KEY("Cesarean surgery" OR "emergency Cesarean delivery" OR "Elective cesarean delivery" OR "Caesarean surgery" OR "emergency Caesarean delivery" OR "Elective caesarean delivery" OR "obstetric surgeries" OR "obstetric surgery" OR "cesarean section methods" OR "Caesarean delivery" OR "Cesarean Sections" OR "Abdominal Delivery" OR "c sections ob" OR "Caesarean Section" OR "Caesarean Sections" OR "delivery abdominal" OR "Abdominal Deliveries" OR "deliveries abdominal" OR "Postcesarean Section" OR "deliveries obstetric" OR "Obstetric Deliveries" OR "Obstetric Delivery") AND PUBYEAR > 1999 AND PUBYEAR < 2025)) AND (TITLE-ABS-KEY("anesthesia general methods" OR "anesthesia" OR "anesthesia obstetrical" OR "General Anesthesia" OR "General Anesthesias") AND PUBYEAR > 1999 AND PUBYEAR < 2025) AND (TITLE-ABS-KEY("Direct laryngoscopy" OR "Direct laryngoscope" OR "Traditional laryngoscopy" OR "Conventional laryngoscopy")))**

Supplementary Figure 1

PRISMA flow chart for Research Question: Does videolaryngoscopy improve the success rate of intubation compared to direct laryngoscopy in parturients undergoing Caesarean delivery under general anaesthesia?

Supplementary Table 1b.

Summary table for included studies for Research Question: Does videolaryngoscopy improve the success rate of intubation compared to direct laryngoscopy in parturients undergoing Caesarean delivery under general anaesthesia?

Author and Year	Journal	Type	Level of Evidence (LOE)	Device	VL Usage Recommendation	VL as Rescue Device?
Howle R (2021)[40]	Can J Anaesth	Systematic Review & Meta-analysis	A	VL vs DL first-attempt success rate, time to tracheal intubation (TTI)	VL improve view, Recommended for difficult airway and rescue use only	Yes
Honarmand A (2024)[70]	Adv Biomed Res	Double-blind RCT	B-R	GlideScope vs DL Haemodynamic respones, TTI, number of attempts	Reduce time to intubate and number of attempts -Recommended for routine use in obstetric intubation	Not specified
Krom AJ (2017)[71]	Anaesthesia	Systematic Review	B-NR* (the data is from obese patients)	VL (all types)	Preferred for emergency C-section (RSI)	Not specified
Critchley JD (2023)[72]	Eur J Anaesthesiol	Prospective Clinical Trial	C-LD	McGrath MAC vs DL	Used routinely	Not specified
Win A (2023)[73]	Proc (Bayl Univ Med Cent)	Retrospective Analysis	C-LD	VL (C-Mac, GlideScope, McGrath) vs DL	More commonly used in difficult airways	Implied
Aziz MF (2012)[74]	Anesth Analg	Retrospective Analysis	C-LD	GlideScope vs DL	Effective in predicted difficult airways	Implied
Stopar Pintarič T (2023)[75]	Biomol Biomed	Narrative Review	C-EO	VL vs DL	Supports routine use, especially Macintosh-type VL	Not specified
Choi SU (2022)[76]	Anesth Pain Med (Seoul)	Review Article	C-EO	VL (not specified)	Supports routine use generally	Not specified
Mushambi MC (2021)[77]	Int Anesthesiol Clin	Review Article	C-EO	VL (not specified)	Recommends routine VL use in obstetrics	Not specified
Patel S (2020)[32]	Curr Anesthesiol Rep	Review Article	C-EO	VL (not specified)	For difficult airway situations	Yes
Alanoglu Z (2016)[78]	Acta Clin Croat	Review Article	C-EO	VL (not specified)	For difficult direct laryngoscopy	Yes
Scott-Brown S (2015)[79]	Int J Obstet Anesth	Review Article	C-EO	VL (not specified)	For difficult or failed intubation	Yes
Finegold H (2013)[80]	Anesthesiol Clin	Review Article	C-EO	VL (not specified)	General support for routine VL use	Not specified
Biro P (2011)[81]	Curr Opin Anaesthesiol	Review Article	C-EO	VL (not specified)	General support for routine VL use	Not specified
Lee YL (2022)[82]	Singapore Med J	Retrospective Observational	C-LD	C-Mac (Macintosh, D Blade)	Used both as primary and after failed DL	Yes
Hunter NM (2020)[83]	Perioper Care Oper Room Manag	Cross-sectional Study	C-LD	VL (not specified)	VL is universally available in obstetric units	Not addressed
Ramkumar V (2016)[7]	Indian J Anaesth	Practice Guidelines	C-EO	VL (not specified)	General recommendation for VL	Not specified
Mushambi MC (2015)[84]	Anaesthesia	Practice Guidelines	C-EO	VL (not specified)	For difficult airway and after failed DL	Yes
Inal MT (2016)[69]	Nobel Med	Clinical Trial	C-LD	TrueView EVO2 vs Macintosh DL	Supports routine use in obstetrics (better view)	Not specified

VL=Videolaryngoscope, DL=Direct laryngoscope, TTI=Time to tracheal intubation, RCT=Randomised controlled trial, RSI=Rapid sequence induction

APPENDIX 2

Research Question 2: Can a supraglottic airway (SGA) be used as a “planned primary airway interface” for Caesarean delivery?

Population - Parturients at term pregnancy undergoing Caesarean delivery under general anaesthesia

Intervention - SGA as planned primary airway interface

Control or Comparison - Intubation

Outcome - Maternal desaturation / APGAR score / Regurgitation

Research Question 3: After successful rescue of the airway with a 2nd generation supraglottic airway, is it advisable to proceed with this device for a planned Caesarean delivery?

Population - Parturients at term pregnancy undergoing Caesarean delivery under general anaesthesia

Intervention - Supraglottic airway as rescue device

Control or Comparison - None

Outcome - Maternal desaturation / APGAR score / Regurgitation

Supplementary Table 2a.

Concept table for Research Question: Can a supraglottic airway (SGA) be used as a “planned primary airway interface” for Caesarean delivery? And after successful rescue of the airway with a 2^nd generation supraglottic airway, is it advisable to proceed with this device for a planned Caesarean delivery?

	Concept 1	Concept 2	Concept 3	Concept 4	Concept 5	Concept 6	Concept 7
Key concepts	Pregnancy	Term pregnancy	Cesarean	GA	Supraglottic airway	Intubation	Rescue
Free text terms/natural language terms (synonyms, UK/ US terminology, medical/ laymen's terms, acronyms/ abbreviations, drug brands, more narrow search terms) Consider: phrase searching, proximity operators, truncation, wildcards, field qualification (e.g. textword)	pregnancies; pregnant; normal pregnancy; pregnancy normal; pregnan*	Parturient Parturitions last trimester. Pregnancy Trimester, Third Third Pregnancy Trimester Third Pregnancy Trimesters Pregnancy, Third Trimester Pregnancies, Third Trimester Third Trimester Pregnancies Third Trimester Pregnancy Trimester, Third Third Trimester Third Trimesters Trimesters, Third Last Trimester Last Trimesters Trimester, Last Trimesters, Last	Cesarean surgery; emergency Cesarean delivery; Elective cesarean delivery; Caesarean surgery; emergency Caesarean delivery; Elective caesarean delivery; obstetric surgeries; obstetric surgery Cesarean Section/ methods* Caesarean delivery Cesarean Sections Abdominal Delivery C-Sections (OB) Caesarean Section Caesarean Sections Delivery, Abdominal Abdominal Deliveries Deliveries, Abdominal Postcesarean Section Deliveries, Obstetric Obstetric Deliveries Obstetric Delivery	Anesthesia, General/ methods* Anesthesia* Anesthesia, Obstetrical/ methods* Anesthesia, Obstetrical* Anesthesias, General General Anesthesia General Anesthesias	(“supraglottal” [All Fields] OR “supraglottic” [All Fields]) AND (“airway” [All Fields] OR “airways” [All Fields] OR “airways” [All Fields])	“intubate”[ All Fields] OR “intubated” [All Fields] OR “intubates” [All Fields] OR “intubating” [All Fields] OR “intubation” [MeSH Terms] OR “intubation” [All Fields] OR “intubations” [All Fields] OR “intubator” [All Fields] OR “intubator s” [All Fields] OR “intubators” [All Fields]	“rescue”[All Fields] OR “rescued” [All Fields] OR “rescues” [All Fields] OR “rescuing” [All Fields]
Controlled vocabulary terms/Subject terms (MeSH terms, Emtree terms) Consider: explode, major headings, subheadings	Pregnancy	’’Term Birth” [Mesh] “Pregnancy Trimester, Third”[Mesh]	Cesarean Section “Cesarean Section” [Mesh] “Cesarean Section” [Mesh: NoExp] “Cesarean Section, Repeat” [Mesh: NoExp]	“Anesthetics, General” [Mesh] “Anesthesia” [Mesh] “Anesthesia, Obstetrical” [Mesh]		“Intubation, Intratracheal” [Mesh]

Search string

PubMed: 346 results

((((“pregnancies"[Title/Abstract] OR "pregnant"[Title/Abstract] OR "normal pregnancy"[Title/Abstract] OR "pregnancy normal" [Title/Abstract] OR "pregnan*" [Title/Abstract] OR "pregnancy" [MeSH Terms]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication])) OR ((("Parturient"[Title/Abstract] OR "Parturitions"[Title/Abstract] OR "Last Trimester"[Title/Abstract] OR "pregnancy trimester third" [Title/Abstract] OR "Third Pregnancy Trimester" [Title/Abstract] OR "Third Pregnancy Trimesters"[Title/Abstract] OR "pregnancy third trimester"[Title/Abstract] OR "pregnancies third trimester"[Title/ Abstract] OR "Third Trimester Pregnancies"[Title/Abstract] OR "Third Trimester Pregnancy"[Title/Abstract] OR "trimester third"[Title/Abstract] OR "Third Trimester"[Title/Abstract] OR "Third Trimesters"[Title/Abstract] OR "trimesters third" [Title/Abstract] OR "Last Trimester" [Title/Abstract] OR "Last Trimesters" [Title/Abstract] OR "trimester last"[Title/Abstract] OR "Term Birth"[MeSH Terms] OR "pregnancy trimester, third"[MeSH Terms]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans"[MeSH Terms] AND "english"[Language])) OR (("Cesarean surgery"[Title/Abstract] OR "emergency Cesarean delivery"[Title/Abstract] OR "Elective cesarean delivery"[Title/Abstract] OR "Caesarean surgery"[Title/ Abstract] OR "emergency Caesarean delivery"[Title/Abstract] OR "Elective caesarean delivery"[Title/Abstract] OR "obstetric surgeries"[Title/Abstract] OR "obstetric surgery"[Title/Abstract] OR "cesarean section methods"[Title/ Abstract] OR "Caesarean delivery"[Title/Abstract] OR "Cesarean Sections"[Title/Abstract] OR "Abdominal Delivery"[Title/Abstract] OR "c sections ob"[Title/Abstract] OR "Caesarean Section"[Title/Abstract] OR "Caesarean Sections"[Title/Abstract] OR "delivery abdominal"[Title/Abstract] OR "Abdominal Deliveries"[Title/Abstract] OR "deliveries abdominal"[Title/Abstract] OR "Postcesarean Section"[Title/Abstract] OR "deliveries obstetric"[Title/ Abstract] OR "Obstetric Deliveries"[Title/Abstract] OR "Obstetric Delivery"[Title/Abstract] OR "Cesarean Section"[MeSH Terms] OR "Cesarean Section"[MeSH Terms:noexp] OR "cesarean section, repeat"[MeSH Terms:noexp]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans"[MeSH Terms] AND "english"[Language])))) AND (("anesthesia general methods"[Title/ Abstract] OR "anesthesia*" [Title/Abstract] OR "anesthesia obstetrical" [Title/Abstract] OR "General Anesthesia" [Title/ Abstract] OR "General Anesthesias"[Title/Abstract] OR "anesthetics, general"[MeSH Terms] OR "Anesthesia"[MeSH Terms] OR "anesthesia, obstetrical"[MeSH Terms]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans"[MeSH Terms] AND "english"[Language])) AND ((((((("supraglottal"[All Fields] OR "supraglottic"[All Fields]) AND ("airway"[All Fields] OR "airway s"[All Fields] OR "airways"[All Fields])) OR ("Intratracheal Intubation"[All Fields] OR "Intratracheal Intubations"[All Fields] OR "intubation endotracheal"[All Fields] OR "Endotracheal Intubation"[All Fields] OR "Endotracheal Intubations"[All Fields] OR "Rapid Sequence Induction"[All Fields] OR "Rapid Sequence Intubation"[All Fields] OR "intubation rapid sequence" [All Fields] OR "Laryngeal Mask" [All Fields] OR "mask laryngeal" [All Fields] OR "masks laryngeal"[All Fields] OR "Laryngeal Mask Airway"[All Fields] OR "airway laryngeal mask"[All Fields] OR "airways laryngeal mask"[All Fields] OR "Laryngeal Mask Airways"[All Fields] OR "Laryngeal Masks"[MeSH Terms] OR "Rapid Sequence Induction and Intubation"[MeSH Terms] OR "intubation, intratracheal"[MeSH Terms])) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication])) OR ("Extraglottic"[All Fields] AND ("airway"[All Fields] OR "airway s"[All Fields] OR "airways"[All Fields]) AND "EGA"[All Fields] AND ("device s"[All Fields] OR "equipment and supplies"[MeSH Terms] OR ("equipment"[All Fields] AND "supplies"[All Fields]) OR "equipment and supplies"[All Fields] OR "device"[All Fields] OR "instrumentation" [MeSH Subheading] OR "instrumentation" [All Fields] OR "devices"[All Fields])) OR ("Supralaryngeal"[All Fields] AND ("airway"[All Fields] OR "airway s"[All Fields] OR "airways"[All Fields])) OR ("Above"[All Fields] AND ("glottis"[MeSH Terms] OR "glottis"[All Fields]) AND ("airway"[All Fields] OR "airway s"[All Fields] OR "airways"[All Fields]) AND ("device s"[All Fields] OR "equipment and supplies"[MeSH Terms] OR ("equipment"[All Fields] AND "supplies"[All Fields]) OR "equipment and supplies"[All Fields] OR "device"[All Fields] OR "instrumentation"[MeSH Subheading] OR "instrumentation"[All Fields] OR "devices"[All Fields])) OR (("Laryngeal Masks"[MeSH Terms] OR ("laryngeal"[All Fields] AND "masks"[All Fields]) OR "Laryngeal Masks"[All Fields] OR ("laryngeal"[All Fields] AND "mask"[All Fields] AND "airway"[All Fields]) OR "Laryngeal Mask Airway"[All Fields]) AND "LMA"[All Fields]) OR ("Laryngeal Masks"[MeSH Terms] OR ("laryngeal"[All Fields] AND "masks"[All Fields]) OR "Laryngeal Masks"[All Fields] OR ("laryngeal"[All Fields] AND "mask"[All Fields]) OR "Laryngeal Mask"[All Fields]) OR ("Esophageal-Tracheal"[All Fields] AND ("airway"[All Fields] OR "airway s"[All Fields] OR "airways"[All Fields]) AND ("device s"[All Fields] OR "equipment and supplies"[MeSH Terms] OR ("equipment"[All Fields] AND "supplies"[All Fields]) OR "equipment and supplies"[All Fields] OR "device"[All Fields] OR "instrumentation"[MeSH Subheading] OR "instrumentation"[All Fields] OR "devices"[All Fields])) OR ("Supralaryngeal"[All Fields] AND ("airway"[All Fields] OR "airway s"[All Fields] OR "airways"[All Fields])) OR (("supraglottal"[All Fields] OR "supraglottic"[All Fields]) AND ("airway management"[MeSH Terms] OR ("airway"[All Fields] AND "management"[All Fields]) OR "airway management"[All Fields]) AND ("device s"[All Fields] OR "equipment and supplies"[MeSH Terms] OR ("equipment"[All Fields] AND "supplies"[All Fields]) OR "equipment and supplies"[All Fields] OR "device"[All Fields] OR "instrumentation"[MeSH Subheading] OR "instrumentation"[All Fields] OR "devices"[All Fields])) OR (("oropharynx"[MeSH Terms] OR "oropharynx"[All Fields] OR "oropharyngeal" [All Fields]) AND ("airway" [All Fields] OR "airway s"[All Fields] OR "airways" [All Fields]) AND ("device s"[All Fields] OR "equipment and supplies"[MeSH Terms] OR ("equipment"[All Fields] AND "supplies"[All Fields]) OR "equipment and supplies"[All Fields] OR "device"[All Fields] OR "instrumentation"[MeSH Subheading] OR "instrumentation"[All Fields] OR "devices"[All Fields])) OR (("pharyngeals"[All Fields] OR "pharynges"[All Fields] OR "pharynx"[MeSH Terms] OR "pharynx"[All Fields] OR "pharyngeal"[All Fields]) AND ("airway"[All Fields] OR "airway s"[All Fields] OR "airways"[All Fields]) AND ("device s"[All Fields] OR "equipment and supplies"[MeSH Terms] OR ("equipment"[All Fields] AND "supplies"[All Fields]) OR "equipment and supplies"[All Fields] OR "device"[All Fields] OR "instrumentation"[MeSH Subheading] OR "instrumentation"[All Fields] OR "devices"[All Fields])) OR "Proseal"[All Fields] OR "Igel"[All Fields] OR ("LMA"[All Fields] AND "Supreme"[All Fields]) OR "lma unique"[All Fields] OR ("lma protector cuff"[All Fields] OR "lma protector"[All Fields] OR "lma protector cuff pilot"[All Fields]) OR ("classic lma"[All Fields] OR "classic lmas"[All Fields]) OR ("air q"[All Fields] OR "air q ila"[All Fields] OR "air q insertion"[All Fields] OR "air q intubating"[All Fields] OR "air q intubating laryngeal"[All Fields] OR "air q intubating laryngeal airway"[All Fields] OR "air q la"[All Fields] OR "air q laryngeal"[All Fields] OR "air q laryngeal airway"[All Fields] OR "air q lma"[All Fields] OR "air q supraglottic"[All Fields] OR "air q supraglottic airway"[All Fields] OR "air q sp"[All Fields] OR "air q sp airway"[All Fields] OR (("baska"[Title/Abstract] NOT "baska"[Author]) NOT "baska"[Affiliation])) OR ("AMBU"[All Fields] AND "AURAGAIN"[All Fields]) OR (("blockbuster"[All Fields] OR "blockbusters"[All Fields]) AND "LMA"[All Fields]) OR ("totaltrack vlm"[All Fields] OR "totaltrackdevice"[All Fields]) OR ("sacovlm"[All Fields] OR "sacovlm group" [All Fields] OR "sacovlm guided" [All Fields] OR "sacovlm guided intubation" [All Fields] OR "sacovlm insertion"[All Fields] OR "sacovlm video laryngeal"[All Fields] OR "sacovlm video laryngeal mask"[All Fields] OR "sacovlm video laryngeal mask vlm"[All Fields] OR "sacovlm video"[All Fields] OR "sacovlmtm"[All Fields] OR "sacovlm tm"[All Fields]) OR ("safelm"[All Fields] OR "safelm tm"[All Fields] OR "safelmtm"[All Fields]) OR "lts d"[All Fields] OR ("king lt"[All Fields] OR "king lt airway"[All Fields] OR "king lt d"[All Fields] OR "king lt d airway"[All Fields] OR "king lt d group"[All Fields] OR "king lt d placement"[All Fields] OR "king lt d use"[All Fields] OR "king lt jr"[All Fields] OR "king lt supralaryngeal"[All Fields] OR "king lt supralaryngeal airway"[All Fields] OR "king lt trade"[All Fields] OR "king lt trade mark"[All Fields] OR "king lts"[All Fields] OR "king lts d"[All Fields])) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans"[MeSH Terms] AND “english"[Language]))

Scopus : 530 results

(TITLE-ABS-KEY(pregnan* OR "normal pregnancy" OR "Third Trimester" OR "Last Trimester")

AND TITLE-ABS-KEY("Cesarean surgery" OR "Elective cesarean delivery" OR "emergency Cesarean delivery" OR "Caesarean Section" OR "obstetric surgery")

AND TITLE-ABS-KEY(anesthesia* OR "General Anesthesia" OR "anesthesia obstetrical")

AND TITLE-ABS-KEY("supraglottal airway" OR "supraglottic airway" OR "Endotracheal Intubation" OR "Laryngeal Mask" OR "Esophageal-Tracheal airway" OR Proseal OR Igel OR "LMA Supreme" OR baska OR AMBU OR AURAGAIN OR "king lt"))

AND PUBYEAR > 1999 AND PUBYEAR < 2025 AND (LIMIT-TO(LANGUAGE, "English"))

Supplementary Figure 2

PRISMA flow chart for Research Question: Can a supraglottic airway (SGA) be used as a “planned primary airway interface” for Caesarean delivery and After successful rescue of the airway with a 2nd generation supraglottic airway, is it advisable to proceed with this device for a planned Caesarean delivery?

Supplementary Table 2b.

Summary table for included studies for Research Question: Can a supraglottic airway (SGA) be used as a “planned primary airway interface” for Caesarean delivery?

Use of supraglottic airway devices as planned primary airway interface in Caesarean delivery
Author (Year)	Journal	Type of Article	Level of Evidence (AHA)	Intervention	Conclusion
White (2020)[61]	Anesth Analg	Systematic review & meta-analysis	A	Various SGAs vs ETT; elective CD; 2236 patients	Inconclusive for primary use; supports 2nd gen SGA post-failure
Han (2001)[51]	Can J Anesth	Prospective study	B-NR	Classic LMA; elective CD; 1067 patients; effective airway in 99%	Supports use in healthy, selected patients
Yao (2012)[53]	Can J Anesth	Prospective observational	B-NR	LMA Supreme; elective/ urgent CD; 700 patients	Supports cautious use in selected patients
Li (2017)[52]	BMC Anesthesiology	Prospective cohort	B-NR	LMA Supreme; Category 2 & 3 CD; 584 patients	Supports use in low-risk parturients
Ahmed (2015)[58]	Ain-Shams J Anesthesiol	Randomised controlled trial	B-R	i-Gel vs ETT; elective CD; 80 parturients	Supports use of i-gel
Panneer (2017)[57]	Anesth Essays Res	Randomised controlled trial	B-R	i-Gel vs ETT; elective CD; 80 patients	Supports use with limitations
Saini (2016)[60]	J Obstet Anaesth Crit Care	Randomised controlled trial	B-R	ProSeal LMA vs ETT; elective CD; 60 patients	Supports use; needs larger studies
Yao (2019)[59]	BMC Anesthesiology	Randomised controlled trial	B-R	LMA Supreme vs ETT; elective CD; 920 patients	Supports equivalence; caution advised
Halaseh (2010)[18]	Anaesth Int Care	Prospective observational	B-NR	ProSeal LMA; elective CD; 3000 cases; 1 regurgitation, no aspiration	Supports use in low-risk patients
Metodiev (2023)[62]	Curr Opin Anesthesiol	Narrative review	C-EO	SGAs; obstetric GA	Calls for more research before routine use
Wong (2020)[63]	Int J Obstet Anesth	Narrative review	C-EO	SADs; SAGFBI in elective/ urgent CD	Supports use in elective/ semi-urgent cases
Geng (2017)[55]	Chin Med J	Retrospective cohort	B-NR	LMA Supreme vs ETT; emergency CD; 180 patients	Suggests safety, needs further studies
Fang (2018)[56]	Scientific Reports	Retrospective case series	B-NR	LMA Supreme; emergency CD; 1039 patients	Supports use, recommends vigilance
Geng (2023)[54]	Front Med	Retrospective cohort	B-NR	LMA Supreme vs ETT; CD under GA	Supports safety, needs further trials

SGA=Supraglottic airway, LMA=Laryngeal mask airway, PLMA=ProSeal laryngeal mask airway, SLMA=Supreme laryngeal mask airway, i-Gel=i-gel supraglottic airway device, ETT=Endotracheal tube, CD=Caesarean delivery, GA=General anaesthesia, RSI=Rapid sequence induction, ASA=American Society of Anesthesiologists, RCT=Randomised controlled trial, SAGFBI=Supraglottic airway-guided fiberoptic bronchoscopic intubation

Supplementary Table 2c.

Summary table for included studies for Research Question: After successful rescue of the airway with a 2nd generation supraglottic airway, is it advisable to proceed with this device for a planned Caesarean delivery?

Use of supraglottic airway devices as rescue devices in Caesarean delivery
Author (Year)	Journal	Type of Article	Level of Evidence (AHA)	Intervention	Conclusion
Awan (2004)[42]	Br J Anaesth	Case Report	C-LD	ProSeal LMA; Emergency CD; Failed intubation	Supports use as rescue
Vaida (2004)[43]	Br J Anaesth	Case Report	C-LD	ProSeal LMA; Elective CD; Failed intubation	Tentatively supports; not yet consensus
Keller (2004)[44]	Anesth Analg	Case Report	C-LD	ProSeal LMA; Urgent CD; Failed intubation	Supports use as rescue
Cook (2005)[45]	Can J Anesth	Case Report	C-LD	ProSeal LMA; Emergency CD; Failed RSI	Supports use as rescue
Sharma (2006)[46]	Int J Obstet Anesth	Case Report	C-LD	ProSeal LMA; Elective and Emergency CD; Failed intubation	Supports use as rescue
Berger (2011)[47]	Anaesth Int Care	Case Report	C-LD	i-gel; Emergency CD; Failed intubation	Supports use as rescue
Minville (2004)[41]	Anesth Analg	Case Report	C-LD	ILMA-Fastrach; Emergency CD; Failed intubation	Supports use as rescue
McDonnell (2009)[48]	Int J Obstet Anesth	Observational Study	B-NR	ProSeal LMA, Classic LMA, ILMA; Various CD categories; Failed intubation	Supports use as rescue
Paech (2010)[49]	Anaesth Intensive Care	Editorial	C-EO	SGA; Elective CD; General GA use	Supports selective use in low-risk patients
Devroe (2015)[50]	Curr Opin Anesthesiol	Review	C-EO	LMA; General CD; Review of use	Supports use as rescue
Patel (2020)[32]	Curr Anesth Rep	Review	C-EO	SGAs; CD; Airway management review	Supports use as rescue under conditions

SGA=Supraglottic airway, LMA=Laryngeal mask airway, i-Gel=i-gel supraglottic airway device, ETT=Endotracheal tube, CD=Caesarean delivery, GA=General anaesthesia, ILMA=Intubating laryngeal mask airway, RSI=Rapid sequence induction

APPENDIX 3

Research Question 4: Is routine application of cricoid force necessary to prevent regurgitation and aspiration in parturients undergoing Caesarean delivery under general anaesthesia?

• Population - Parturients at term pregnancy undergoing Caesarean delivery under GA

• Intervention - Sellick’s manoeuvre / Cricoid force / RSI

• Control or comparison - No cricoid force

• Outcome - Reduced incidence of regurgitation

Supplementary Table 3a.

Concept table for Research Question: Is routine application of cricoid force necessary to prevent regurgitation and aspiration in parturients undergoing Caesarean delivery under general anaesthesia?

Research Question	Concept 1	Concept 2	Concept 3	Concept 4	Concept 5
Key concepts	Pregnancy	Term pregnancy	Caesarean	GA	Sellick's manoeuvre/Cricoid force
Free text terms/ natural language terms (synonyms, UK/ US terminology, medical/laymen's terms, acronyms/ abbreviations, drug brands, more narrow search terms) Consider: phrase searching, proximity operators, truncation, wildcards, field qualification (e.g. textword)	pregnancies; pregnant; normal pregnancy; pregnancy normal; pregnan*	Parturient Parturitions last trimester. Pregnancy Trimester, Third Third Pregnancy Trimester Third Pregnancy Trimesters Pregnancy, Third Trimester Pregnancies, Third Trimester Third Trimester Pregnancies Third Trimester Pregnancy Trimester, Third Third Trimester Third Trimesters Trimesters, Third Last Trimester Last Trimesters Trimester, Last Trimesters, Last	Cesarean surgery; emergency Cesarean delivery; Elective cesarean delivery; Caesarean surgery; emergency Caesarean delivery; Elective caesarean delivery; obstetric surgeries; obstetric surgery Cesarean Section/ methods* Caesarean delivery Cesarean Sections Abdominal Delivery C-Sections (OB) Caesarean Section Caesarean Sections Delivery, Abdominal Abdominal Deliveries Deliveries, Abdominal Postcesarean Section Deliveries, Obstetric Obstetric Deliveries Obstetric Delivery	Anesthesia, General/ methods* Anesthesia* Anesthesia, Obstetrical/methods* Anesthesia, Obstetrical* Anesthesias, General General Anesthesia General Anesthesias	((“sellick”[All Fields] OR “sellick s”[All Fields]) AND (“maneuver”[All Fields] OR “maneuvered”[All Fields] OR “maneuvering”[All Fields] OR “maneuverings”[All Fields] OR “maneuvers”[All Fields] OR “manoeuvrability”[All Fields] OR “manoeuvrable”[All Fields] OR “manoeuvre”[All Fields] OR “manoeuvred”[All Fields] OR “manoeuvres”[All Fields] OR “manoeuvring”[All Fields])) AND ((humans[Filter]) AND (english[Filter])) (“cricoid force”[All Fields] OR “cricoid force application”[All Fields] OR “cricoid forces”[All Fields] OR “cricoid pressure”[All Fields] OR “cricoid pressure application”[All Fields] OR “cricoid pressure decreases”[All Fields] OR “cricoid pressure force”[All Fields] OR “cricoid pressure group”[All Fields] OR “cricoid pressure induced”[All Fields] OR “cricoid pressure induced relaxation”[All Fields] OR “cricoid pressure maneuver”[All Fields] OR “cricoid pressure maneuvers”[All Fields]) AND ((humans[Filter]) AND (english[Filter]))
Controlled vocabulary terms/ Subject terms (MeSH terms, Emtree terms) Consider: explode, major headings, subheadings	Pregnancy	“Term Birth”[Mesh] “Pregnancy Trimester, Third”[Mesh]	Cesarean Section “Cesarean Section”[Mesh] “Cesarean Section”[Mesh: NoExp] “Cesarean Section, Repeat”[Mesh: NoExp]	“Anesthetics, General”[Mesh] “Anesthesia”[Mesh] “Anesthesia, Obstetrical”[Mesh]

Search String:

PubMed: 44 results

(((("Parturient"[Title/Abstract] OR "Parturitions" [Title/Abstract] OR "Last Trimester" [Title/Abstract] OR "pregnancy trimester third"[Title/Abstract] OR "Third Pregnancy Trimester"[Title/Abstract] OR "Third Pregnancy Trimesters"[Title/Abstract] OR "pregnancy third trimester"[Title/Abstract] OR "pregnancies third trimester"[Title/ Abstract] OR "Third Trimester Pregnancies"[Title/Abstract] OR "Third Trimester Pregnancy"[Title/Abstract] OR "trimester third"[Title/Abstract] OR "Third Trimester"[Title/Abstract] OR "Third Trimesters"[Title/Abstract] OR "trimesters third" [Title/Abstract] OR "Last Trimester" [Title/Abstract] OR "Last Trimesters" [Title/Abstract] OR "trimester last"[Title/Abstract] OR "Term Birth"[MeSH Terms] OR "pregnancy trimester, third"[MeSH Terms]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans"[MeSH Terms] AND "english"[Language])) OR (("Cesarean surgery"[Title/Abstract] OR "emergency Cesarean delivery"[Title/Abstract] OR "Elective cesarean delivery"[Title/Abstract] OR "Caesarean surgery"[Title/ Abstract] OR "emergency Caesarean delivery"[Title/Abstract] OR "Elective caesarean delivery"[Title/Abstract] OR "obstetric surgeries"[Title/Abstract] OR "obstetric surgery"[Title/Abstract] OR "cesarean section methods"[Title/ Abstract] OR "Caesarean delivery"[Title/Abstract] OR "Cesarean Sections"[Title/Abstract] OR "Abdominal Delivery"[Title/Abstract] OR "c sections ob"[Title/Abstract] OR "Caesarean Section"[Title/Abstract] OR "Caesarean Sections"[Title/Abstract] OR "delivery abdominal"[Title/Abstract] OR "Abdominal Deliveries"[Title/Abstract] OR "deliveries abdominal"[Title/Abstract] OR "Postcesarean Section"[Title/Abstract] OR "deliveries obstetric"[Title/ Abstract] OR "Obstetric Deliveries"[Title/Abstract] OR "Obstetric Delivery"[Title/Abstract] OR "Cesarean Section"[MeSH Terms] OR "Cesarean Section"[MeSH Terms:noexp] OR "cesarean section, repeat"[MeSH Terms:noexp]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans"[MeSH Terms] AND "english"[Language])) OR (("anesthesia general methods"[Title/ Abstract] OR "anesthesia*"[Title/Abstract] OR "anesthesia obstetrical" [Title/Abstract] OR "General Anesthesia"[Title/Abstract] OR "General Anesthesias"[Title/Abstract] OR "anesthetics, general"[MeSH Terms] OR "Anesthesia"[MeSH Terms] OR "anesthesia, obstetrical"[MeSH Terms]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans"[MeSH Terms] AND "english"[Language]))) AND (((("cricoid force"[All Fields] OR "cricoid force application"[All Fields] OR "cricoid forces"[All Fields] OR "cricoid pressure application"[All Fields] OR "cricoid pressure decreases"[All Fields] OR "cricoid pressure force"[All Fields] OR "cricoid pressure group"[All Fields] OR "cricoid pressure induced"[All Fields] OR "cricoid pressure induced relaxation"[All Fields] OR "cricoid pressure maneuver"[All Fields] OR "cricoid pressure maneuvers"[All Fields] OR "cricoid pressure providers"[All Fields] OR "cricoid pressure simulator"[All Fields] OR "cricoid pressure trainer"[All Fields] OR "cricoid pressure training"[All Fields]) AND ("humans"[MeSH Terms] AND "english"[Language])) OR ("sellick s maneuver"[All Fields] OR "sellick s manoeuvre"[All Fields] OR "sellick manoeuvre"[All Fields] OR "sellick manover"[All Fields]) OR "BURP"[All Fields] OR "OELM"[All Fields]) AND 2000/01/01:2024/12/31[Date - Publication] AND ("humans"[MeSH Terms] AND "english"[Language]))) AND ((humans[Filter]) AND (english[Filter]))

Scopus : 245 results

TITLE-ABS-KEY ( ( "cricoid force" OR "cricoid pressure application" OR "cricoid maneuver" OR "Sellick maneuver" OR "BURP" OR "OELM" ) ) AND PUBYEAR > 1998 AND PUBYEAR < 2025 AND ( LIMITTO ( EXACTKEYWORD , "Human" ) OR LIMITTO ( EXACTKEYWORD , "Humans" ) OR LIMITTO ( EXACTKEYWORD , "Female" ) OR LIMIT-TO ( EXACTKEYWORD , "Cricoid Pressure" ) OR LIMIT-TO ( EXACTKEYWORD , "BURP" ) OR LIMIT- TO ( EXACTKEYWORD , "Burp" ) OR LIMIT-TO ( EXACTKEYWORD , "Cricoid Cartilage" ) OR LIMIT-TO ( EXACTKEYWORD , "Cricoid" ) ) AND ( LIMITTO ( SUBJAREA , "MEDI" ) )

Supplementary Figure 3

PRISMA flow chart for Research Question: Is routine application of cricoid force necessary to prevent regurgitation and aspiration in parturients undergoing Caesarean delivery under general anaesthesia?

Supplementary Table 3b.

Summary table for included studies for Research Question: Is routine application of cricoid force necessary to prevent regurgitation and aspiration in parturients undergoing Caesarean delivery under general anaesthesia?

Author (Year)	Journal	Type of Article	Level of Evidence (AHA)	Intervention	Remarks	Supports Cricoid Force for aspiration prevention	Cricoid Force not harmful
Birenbaum A (2018)[86]	JAMA Surg	Randomised, multicentre, non-inferiority double-blind RCT	B-R	Cricoid pressure vs Sham	No significant difference in aspiration; CP increased intubation difficulty	No	No - CP increased intubation difficulty
Gupta M (2024)[89]	Int J Obstet Anaesth	Non-inferiority RCT	B-R	Cricoid pressure vs Para-laryngeal pressure	Para-laryngeal pressure non-inferior to CP in esophageal occlusion and intubation outcomes	No	Yes - No deterioration in intubation performance
Hung KC (2021)[88]	Can J Anaesth	Systematic review and meta-analysis	B-R*	Cricoid pressure vs No CP	CP did not impact SFAIR or views; may slightly prolong intubation and cause hoarseness	No	Yes - No impact on SFAIR or views; minor effects only
White L (2020)[87]	Heart Lung	Systematic review and meta-analysis	B-R*	Cricoid pressure vs Sham	CP did not reduce aspiration; increased intubation difficulty	No	No - Increased difficulty in intubation noted
Fenton PM (2009)[85]	Int J Obstet Anaesth	Observational study in pregnant patients	B-NR	Cricoid pressure in C-sections	No protective effect of CP in preventing regurgitation or death	No	No - No benefit and not specifically assessed as safe
Tessarolo E (2022)[90]	Emerg Med Australas	Systematic review and meta-analysis in ED patients	B-R*	Cricoid pressure vs No CP (ED patients)	CP did not affect FPS or prevent aspiration	No	Yes - No increase in complications; neutral effect

* Level was downgraded as studies may not have been done on pregnant patients. CP=Cricoid pressure/force, FPS=First pass success, SFAIR=Successful first-attempt intubation rate, RCT=Randomised controlled trial, AHA=American Heart Association

APPENDIX 4

Research Question 5: Does high-flow nasal oxygen during preoxygenation and continued during apnoea versus face mask preoxygenation reduce peri-induction desaturation in parturients undergoing Caesarean delivery under general anaesthesia?

P (Population): Parturients (pregnant women) undergoing Caesarean section under general anaesthesia

I (Intervention): High-flow nasal oxygen (HFNO) guided preoxygenation

C (Comparison): Standard face mask preoxygenation

O (Outcome): Incidence of desaturation during induction, time to desaturation, oxygen saturation levels, and patient safety indicators

Supplementary Table 4a.

Concept table for Research Question: Does high-flow nasal oxygen during preoxygenation and continued during apnoea versus face mask preoxygenation reduce peri-induction desaturation in parturients undergoing Caesarean delivery under general anaesthesia?

	Population (P)	Intervention (I)	Comparison (C)	Outcome (O)
Concept	Adults undergoing general anesthesia	High-flow nasal oxygen (HFNO) preoxygenation	Standard face mask preoxygenation	Oxygenation efficiency and safety during induction
Free Text Terms	“surgical patients”, “adults”, “elective surgery”, “general anesthesia”, “anesthesia induction”	“high flow nasal oxygen”, “HFNO”, “HFNC”, “transnasal humidified rapid insufflation ventilatory exchange”, “THRIVE”, “high-flow nasal cannula”	“face mask”, “facemask”, “standard preoxygenation”, “conventional oxygenation”	“oxygen saturation”, “SpO2”, “desaturation”, “time to desaturation”, “safe apnea time”, “regurgitation”, “aspiration”, “intubation safety”, “airway management”
Controlled Vocabulary/ MeSH Terms	'Anesthesia, General' [MeSH], 'Surgical Procedures, Operative' [MeSH], 'Adult' [MeSH]	'Oxygen Inhalation Therapy' [MeSH], 'High-Flow Nasal Cannula' [Supplementary Concept]	'Masks' [MeSH], 'Oxygen Inhalation Therapy' [MeSH]	'Hypoxia' [MeSH], 'Oxygen' [MeSH], 'Respiration' [MeSH], 'Patient Safety' [MeSH], 'Airway Management' [MeSH]

Search String:

PubMed search string: 3 results

("High-Flow Nasal Oxygen"[MeSH Terms] OR "high-flow nasal oxygen" OR "HFNO" OR "high-flow nasal cannula" OR "HFNC" OR "transnasal humidified rapid insufflation ventilatory exchange" OR "THRIVE") AND ("Preoxygenation"[MeSH Terms] OR "preoxygenation")

AND

("Pregnancy"[MeSH Terms] OR "pregnant women" OR "parturients")

AND

("Cesarean Section"[MeSH Terms] OR "cesarean section" OR "C-section")

AND

("Anesthesia, General"[MeSH Terms] OR "general anesthesia")

AND

("2000/01/01"[PDAT] : "2024/12/31"[PDAT])

Scopus search string: 11 results

(TITLE-ABS-KEY("high flow nasal oxygen" OR HFNO OR "high flow nasal cannula" OR HFNC OR THRIVE OR "transnasal humidified rapid insufflation ventilatory exchange"))

AND

(TITLE-ABS-KEY(preoxygenation OR "pre-oxygenation"))

AND

(TITLE-ABS-KEY("cesarean section" OR "caesarean section" OR "C-section"))

AND

(TITLE-ABS-KEY("pregnant women" OR parturient OR pregnancy))

AND

(TITLE-ABS-KEY("general anesthesia")) AND (PUBYEAR > 1999 AND PUBYEAR < 2025)

Supplementary Figure 4

PRISMA flow chart for Research Question;Does high-flow nasal oxygen during preoxygenation and continued during apnoea versus face mask preoxygenation reduce peri-induction desaturation in parturients undergoing Caesarean delivery under general anaesthesia?

Supplementary Table 4a.

Concept table for Research Question: Does high-flow nasal oxygen during preoxygenation and continued during apnoea versus face mask preoxygenation reduce peri-induction desaturation in parturients undergoing Caesarean delivery under general anaesthesia?

	Population (P)	Intervention (I)	Comparison (C)	Outcome (O)
Concept	Adults undergoing general anesthesia	High-flow nasal oxygen (HFNO) preoxygenation	Standard face mask preoxygenation	Oxygenation efficiency and safety during induction
Free Text Terms	“surgical patients”, “adults”, “elective surgery”, “general anesthesia”, “anesthesia induction”	“high flow nasal oxygen”, “HFNO”, “HFNC”, “transnasal humidified rapid insufflation ventilatory exchange”, “THRIVE”, “high-flow nasal cannula”	“face mask”, “facemask”, “standard preoxygenation”, “conventional oxygenation”	“oxygen saturation”, “SpO2”, “desaturation”, “time to desaturation”, “safe apnea time”, “regurgitation”, “aspiration”, “intubation safety”, “airway management”
Controlled Vocabulary/ MeSH Terms	'Anesthesia, General' [MeSH], 'Surgical Procedures, Operative' [MeSH], 'Adult' [MeSH]	'Oxygen Inhalation Therapy' [MeSH], 'High-Flow Nasal Cannula' [Supplementary Concept]	'Masks' [MeSH], 'Oxygen Inhalation Therapy' [MeSH]	'Hypoxia' [MeSH], 'Oxygen' [MeSH], 'Respiration' [MeSH], 'Patient Safety' [MeSH], 'Airway Management' [MeSH]

Supplementary Table 4b.

Summary table for included studies for Research Question: Does high-flow nasal oxygen during preoxygenation and continued during apnoea versus face mask preoxygenation reduce peri-induction desaturation in parturients undergoing Caesarean delivery under general anaesthesia?

Author (Year)	Journal	Type of Article	Level of Evidence (AHA)	Intervention	Remarks on HFNO Superiority vs Face Mask
Shippam W (2019)[92]	Anaesthesia	Non-randomised physiological crossover trial	B-NR	HFNO (30➢W0 L) vs Face mask preoxgyenation (15 L), Objective- EtO2 >0.9	HFNO was shown to be inferior in achieving end tidal oxygen
Al-Sulttan S (2021)[93]	Int J Obstet Anesth	Up-down sequential allocation trial (observational dose-finding)	B-NR	Evaluation of HFNO (50 L/min) use preoxygenation Objective- EtO2 >0.9	HFNO was shown to be inferior in preoxygenation
Osman YM (2021)[13]	Trends Anaesth Crit Care	Randomised controlled trial	B-R	HFNO (Preoxygenation+Apnoeic oxgyenation, 30➢50 L-Optiflow) vs Face mask preoxygenation (6 L 100 O2) + LFNO ( 6 L/min, nasal cannula, apnoeic oxygenation ): for safe apnoea time	HFNO was shown to be beneficial or superior
Zhou S (2021)[94]	Eur J Anaesthesiol	Prospective Randomised clinical trial	B-R	HFNO (50 L, close mouth, 3 min) vs standard facemask (10 L, 3 min) preoxygenation Objective: measuring PaO2 after intubation	HFNO was shown to be beneficial or superior in oxygenation or apnoea time.
Au K (2020)[95]	Anaesthesia	Biased-coin up-down sequential allocation trial	B-NR	Face mask (15 L) vs HFNO (50 L) vs HFNO (50 L ) + no flow oxygen mask. Objective: EtO2 >0.9	HFNO was not found to be superior or was less effective than face mask preoxygenation
Wong CA (2022)[35]	Br J Anaesth	Editorial	C-EO	Preoxgyenation with face mask + LFNO (15 L after anaesthesia) vs HFNO preoxygenatin + HFNO (50-70 L)	HFNO discussed without clear comparative evidence or inconclusive results.
Patel S (2020)[32]	Curr Anesthesiol Rep	Review	C-LD	Literature review of HFNO applications in obstetric anaesthesia	HFNO discussed without clear comparative evidence or inconclusive results.
Tan PCF (2024)[96]	British Journal of Anaesthesia	Prospective observational study	B-NR	HFNO prexoygenation- 30 L (30 s)➢ 50 L (150 s). Objective was EtO2	HFNO was able to achieve EtO2 of 0.9 in only 60%
Hengen M (2017)[91]	A A Case Rep	Case report	C-LD	Use of HFNO (70 L) Preoxygenation + apnoeic oxygenation in parturient with pneumonia and heart failure	HFNO useful in such situation, Improved oxygenation and maintained during induction

HFNO=High-flow nasal oxygenation, LFNO=Low-flow nasal oxygenation, EtO2=End-tidal oxygen concentration, LOE=Level of Evidence, AHA=American Heart Association, L=Litre, min=Minute, s=Seconds

APPENDIX 5

Research Question 6: Compared to low flow nasal oxygen (LFNO), does apnoeic oxygenation using high flow nasal oxygen (HFNO) provide better oxygenation and reduce the risk of hypoxaemia during the apnoeic period in parturients undergoing Caesarean delivery under general anaesthesia?

• P (Population): Parturients undergoing Caesarean delivery under general anaesthesia

• I (Intervention): Apnoeic oxygenation using high-flow nasal oxygen (HFNO)

• C (Comparison): Apnoeic oxygenation using low-flow nasal oxygen (LFNO)

• O (Outcome): Improved oxygenation parameters during apnoeic period (e.g., prolonged safe apnoea time, higher oxygen saturation, reduced incidence of desaturation or hypoxaemia)

Supplementary Table 5a.

Concept table for Research Question: Compared to low flow nasal oxygen (LFNO), does apnoeic oxygenation using high flow nasal oxygen (HFNO) provide better oxygenation and reduce the risk of hypoxaemia during the apnoeic period in parturients undergoing Caesarean delivery under general anaesthesia?

Element	Population	Intervention	Comparator	Outcome	Apnoeic Oxygenation
Free Text Terms	“pregnant women”, “parturients”, “obstetric”, “cesarean”, “C-section”, “general anesthesia”	“high flow nasal oxygen”, “HFNO”, “humidified high flow”, “high flow therapy”	“low flow nasal oxygen”, “LFNO”, “nasal cannula”, “standard nasal oxygen”	“oxygenation”, “desaturation”, “hypoxemia”, “apnea tolerance”, “safe apnea duration”	“apneic oxygenation”, “apnoeic oxygenation”, “apnea oxygenation”, “oxygen diffusion”
Controlled Vocabulary (MeSH/Emtree)	“Pregnant Women”[MeSH], “Cesarean Section”[MeSH], “Anesthesia, General”[MeSH]	“Oxygen Inhalation Therapy”[MeSH], “High-Flow Nasal Cannula”[Supplementary Concept]	“Oxygen Inhalation Therapy”[MeSH], “Nasal Cannula”[MeSH]	“Oxygenation”[MeSH], “Hypoxia”[MeSH], “Apnea”[MeSH]	“Apneic Oxygenation”[All Fields], “Oxygen Diffusion”[MeSH or All Fields]

Search string:

PubMed: 168 results

(((("pregnancies"[Title/Abstract] OR "pregnant"[Title/Abstract] OR "normal pregnancy"[Title/Abstract] OR "pregnancy normal"[Title/Abstract] OR "pregnan*"[Title/Abstract] OR "pregnancy"[MeSH Terms]) AND ("humans" [MeSH Terms] AND "english"[Language])) OR (("Parturient"[Title/Abstract] OR "Parturitions" [Title/ Abstract] OR "Last Trimester"[Title/Abstract] OR "pregnancy trimester third"[Title/Abstract] OR "Third Pregnancy Trimester"[Title/Abstract] OR "Third Pregnancy Trimesters"[Title/Abstract] OR "pregnancy third trimester"[Title/ Abstract] OR "pregnancies third trimester"[Title/Abstract] OR "Third Trimester Pregnancies"[Title/Abstract] OR "Third Trimester Pregnancy"[Title/Abstract] OR "trimester third"[Title/Abstract] OR "Third Trimester"[Title/ Abstract] OR "Third Trimesters"[Title/Abstract] OR "trimesters third"[Title/Abstract] OR "Last Trimester"[Title/ Abstract] OR "Last Trimesters"[Title/Abstract] OR "trimester last"[Title/Abstract] OR "Term Birth"[MeSH Terms] OR "pregnancy trimester, third"[MeSH Terms]) AND ("humans"[MeSH Terms] AND "english"[Language]))) AND ((((((((((((((((((((((((((("apnea"[MeSH Terms] OR "apnea"[All Fields] OR "apneic"[All Fields] OR "apnoeic"[All Fields] OR "apneics"[All Fields] OR "apnoeics"[All Fields]) AND ("ventilated" [All Fields] OR "ventilates" [All Fields] OR "ventilating"[All Fields] OR "ventilation"[MeSH Terms] OR "ventilation"[All Fields] OR "ventilate"[All Fields] OR "ventilations"[All Fields] OR "ventilator s"[All Fields] OR "ventilators, mechanical"[MeSH Terms] OR ("ventilators"[All Fields] AND "mechanical"[All Fields]) OR "mechanical ventilators"[All Fields] OR "ventilator"[All Fields] OR "ventilators"[All Fields] OR "ventillation"[All Fields])) OR ("apneic oxygenation"[All Fields] OR "apneic oxygenation method"[All Fields] OR "apneic oxygenation techniques"[All Fields] OR ("para oxygenation" [All Fields] OR "para oxysubstituted"[All Fields]) OR ("oxygen diffusion" [All Fields] OR "oxygen diffusion capacity"[All Fields] OR "oxygen diffusion concentration"[All Fields] OR "oxygen diffusion kinetics"[All Fields]) OR ("Respiration"[MeSH Terms] OR "Respiration"[All Fields] OR "respirations"[All Fields] OR "respirational"[All Fields] OR "respirative"[All Fields] OR "respiratively"[All Fields] OR "respire"[All Fields] OR "respired" [All Fields] OR "respirer"[All Fields] OR "respirers"[All Fields] OR "respires" [All Fields] OR "respiring"[All Fields]) OR (("transnasal"[All Fields] OR "transnasally"[All Fields]) AND ("humidified"[All Fields] OR "humidifiers"[MeSH Terms] OR "humidifiers"[All Fields] OR "humidifier"[All Fields] OR "humidifies"[All Fields] OR "humidify"[All Fields] OR "humidifying"[All Fields]) AND ("rapid"[All Fields] OR "rapidities"[All Fields] OR "rapidity"[All Fields] OR "rapidness"[All Fields]) AND ("insufflate"[All Fields] OR "insufflated"[All Fields] OR "insufflating"[All Fields] OR "insufflation"[MeSH Terms] OR "insufflation"[All Fields] OR "insufflations"[All Fields] OR "insufflator"[All Fields] OR "insufflators"[All Fields]) AND "ventilatory"[All Fields] AND ("exchangable"[All Fields] OR "exchange"[All Fields] OR "exchangeabilities"[All Fields] OR "exchangeability"[All Fields] OR "exchangeable"[All Fields] OR "exchanged"[All Fields] OR "exchanger"[All Fields] OR "exchanger s"[All Fields] OR "exchangers"[All Fields] OR "exchanges"[All Fields] OR "exchanging"[All Fields]) AND ("thrive"[All Fields] OR "thrived"[All Fields] OR "thrives"[All Fields] OR "thriving"[All Fields])))) AND ("humans"[MeSH Terms] AND "english"[Language])) OR "HFNC"[Title/Abstract]) AND ("humans"[MeSH Terms] AND "english"[Language])) OR "HFNO"[Title/Abstract]) AND ("humans"[MeSH Terms] AND "english"[Language])) OR (("apnea"[MeSH Terms] OR "apnea"[All Fields] OR "apneic"[All Fields] OR "apnoeic"[All Fields] OR "apneics"[All Fields] OR "apnoeics"[All Fields]) AND ("oxygenation"[All Fields] OR "oxygen"[MeSH Terms] OR "oxygen"[All Fields] OR "oxygen s"[All Fields] OR "oxygenate"[All Fields] OR "oxygenated"[All Fields] OR "oxygenates"[All Fields] OR "oxygenating"[All Fields] OR "oxygenations"[All Fields] OR "oxygenative"[All Fields] OR "oxygenator s"[All Fields] OR "oxygenators"[MeSH Terms] OR "oxygenators"[All Fields] OR "oxygenator"[All Fields] OR "oxygene"[All Fields] OR "oxygenic"[All Fields] OR "oxygenous"[All Fields] OR "oxygens"[All Fields] OR "oxygenation" [All Fields]) AND ("humans" [MeSH Terms] AND "english"[Language]))) AND ("humans" [MeSH Terms] AND "english"[Language])) OR ("nasal oxygen"[All Fields] OR "nasal oxygen administration"[All Fields] OR "nasal oxygen application"[All Fields] OR "nasal oxygen cannula"[All Fields] OR "nasal oxygen cannulae"[All Fields] OR "nasal oxygen cannulas"[All Fields] OR "nasal oxygen catheter"[All Fields] OR "nasal oxygen catheters" [All Fields] OR "nasal oxygen delivery" [All Fields] OR "nasal oxygen flow" [All Fields] OR "nasal oxygen flow rates"[All Fields] OR "nasal oxygen h fno"[All Fields] OR "nasal oxygen hfn"[All Fields] OR "nasal oxygen hfnc"[All Fields] OR "nasal oxygen hfno"[All Fields] OR "nasal oxygen hfno therapy"[All Fields] OR "nasal oxygen insufflation"[All Fields] OR "nasal oxygen mask"[All Fields] OR "nasal oxygen prongs"[All Fields] OR "nasal oxygen inhalation"[All Fields] OR "nasal oxygen therapy"[All Fields] OR "nasal oxygen treatment"[All Fields])) AND ("humans"[MeSH Terms] AND "english"[Language])) OR ("nasal insufflation"[All Fields] OR "nasal insufflation catheters"[All Fields] OR "nasal insufflation snorting"[All Fields] OR "nasal insufflations"[All Fields] OR "nasal insufflator"[All Fields])) AND ("humans"[MeSH Terms] AND "english"[Language])) OR (("diffusable"[All Fields] OR "diffusant"[All Fields] OR "diffusants"[All Fields] OR "diffuse"[All Fields] OR "diffusely"[All Fields] OR "diffuses"[All Fields] OR "diffusibility"[All Fields] OR "diffusible"[All Fields] OR "diffusion"[MeSH Terms] OR "diffusion"[All Fields] OR "diffused"[All Fields] OR "diffusing"[All Fields] OR "diffusions"[All Fields] OR "diffusive"[All Fields] OR "diffusively"[All Fields] OR "diffusivities"[All Fields] OR "diffusivity"[All Fields]) AND ("Respiration" [MeSH Terms] OR "Respiration" [All Fields] OR "respirations" [All Fields] OR "respirational"[All Fields] OR "respirative"[All Fields] OR "respiratively"[All Fields] OR "respire"[All Fields] OR "respired"[All Fields] OR "respirer"[All Fields] OR "respirers"[All Fields] OR "respires"[All Fields] OR "respiring"[All Fields]) AND ("humans"[MeSH Terms] AND "english"[Language]))) AND ("humans"[MeSH Terms] AND "english"[Language])) OR ("SponTaneous"[Title] AND "Respiration"[Title] AND "IntraVEnous"[Title] AND "anaesthesia"[Title] AND "Hi- flow"[Title] AND "nasal"[Title] AND "oxygen"[Title]) OR "Optiflow"[All Fields]) AND ("humans"[MeSH Terms] AND "english"[Language])) OR "Airvo"[All Fields]) AND ("humans"[MeSH Terms] AND "english"[Language])) OR "CPAP"[All Fields]) AND ("humans"[MeSH Terms] AND "english"[Language])) OR ((("nasal"[All Fields] AND "cannula"[All Fields]) OR "nasal cannula"[All Fields]) AND ("humans"[MeSH Terms] AND "english"[Language]))) AND ("humans"[MeSH Terms] AND "english"[Language])) OR ("nasalance"[All Fields] OR "nasality"[All Fields] OR "nasalization"[All Fields] OR "nasalized"[All Fields] OR "nasally"[All Fields] OR "nose"[MeSH Terms] OR "nose"[All Fields] OR "nasal"[All Fields] OR "nasals"[All Fields])) AND ("trumpet"[All Fields] OR "trumpets"[All Fields]) AND ("humans"[MeSH Terms] AND "english"[Language]) AND ("humans"[MeSH Terms] AND "english"[Language]) AND ("humans"[MeSH Terms] AND "english"[Language])) OR (("face mask ventilation"[All Fields] OR ("positive pressure ventilation"[All Fields] OR "positive pressure ventilation devices"[All Fields])) AND ("humans"[MeSH Terms] AND "english"[Language]) AND ("humans"[MeSH Terms] AND "english"[Language])))) AND ((humans[Filter]) AND (english[Filter]) AND (2000:2024[pdat]))

Scopus :118 results

( TITLE-ABS-KEY ( pregnancies OR pregnant OR "normal pregnancy" OR "pregnancy normal" OR pregnan* ) AND PUBYEAR > 1999 AND PUBYEAR < 2025 AND LANGUAGE ( english ) ) OR ( TITLE-ABS-KEY ( parturient OR parturitions OR "Last Trimester" OR "pregnancy trimester third" OR "Third Pregnancy Trimester" OR "Third Pregnancy Trimesters" OR "pregnancy third trimester" OR "Third Trimester Pregnancies" OR "Third Trimester Pregnancy" OR "Third Trimester" OR "Term Birth" ) AND PUBYEAR > 1999 AND PUBYEAR < 2025 AND LANGUAGE ( english ) ) AND ( TITLE-ABS-KEY ( apnea OR apneic OR apnoeic ) AND TITLE-ABS-KEY ( ventilated OR ventilates OR ventilating OR ventilation OR ventilator* OR "mechanical ventilators" OR ventilation ) OR TITLE-ABS-KEY ( "apneic oxygenation" OR "oxygen diffusion" OR transnasal AND humidified AND rapid AND insufflate AND ventilatory AND exchangeable AND thrive ) AND PUBYEAR > 1999 AND PUBYEAR < 2025 AND LANGUAGE ( english ) ) OR ( TITLE-ABS-KEY ( "nasal oxygen" OR "nasal oxygen administration" OR "nasal oxygen cannula" OR "nasal oxygen catheter" OR "nasal oxygen delivery" OR "nasal oxygen flow rates" OR "nasal oxygen HFNO" OR "nasal oxygen insufflation" OR "nasal oxygen therapy" ) AND PUBYEAR > 1999 AND PUBYEAR < 2025 AND LANGUAGE ( english ) ) OR ( TITLE-ABS-KEY ( "nasal insufflation" OR "nasal insufflation catheters" ) AND PUBYEAR > 1999 AND PUBYEAR < 2025 AND LANGUAGE ( english ) ) OR ( TITLE-ABS-KEY ( diffusable OR diffuse OR diffusibility OR diffusion ) AND TITLE-ABS-KEY ( respiration ) AND PUBYEAR > 1999 AND PUBYEAR < 2025 AND LANGUAGE ( english ) ) AND ( TITLE-ABS-KEY ( spontaneous AND respiration AND intravenous AND anaesthesia AND hi- flow AND nasal AND oxygen ) OR TITLE-ABS-KEY ( optiflow OR airvo OR cpap ) AND PUBYEAR > 1999 AND PUBYEAR < 2025 AND LANGUAGE ( english ) ) OR ( TITLE-ABS-KEY ( "nasal cannula" ) AND PUBYEAR > 1999 AND PUBYEAR < 2025 AND LANGUAGE ( english ) ) OR ( TITLE-ABS-KEY ( nasalance OR nasalization OR nasally OR nasal ) AND TITLE-ABS-KEY ( trumpet OR trumpets ) ) OR ( TITLE-ABS-KEY ( "face mask ventilation" OR "positive pressure ventilation" ) AND PUBYEAR > 1999 AND PUBYEAR < 2025 AND LANGUAGE ( english ) )

Supplementary Figure 5

PRISMA flow chart for research question: Compared to low flow nasal oxygen (LFNO), does apnoeic oxygenation using high flow nasal oxygen (HFNO) provide better oxygenation and reduce the risk of hypoxaemia during the apnoeic period in parturients undergoing Caesarean delivery under general anaesthesia?

Supplementary Table 5b.

Summary table for included studies for Research Question: Compared to low flow nasal oxygen (LFNO), does apnoeic oxygenation using high flow nasal oxygen (HFNO) provide better oxygenation and reduce the risk of hypoxaemia during the apnoeic period in parturients undergoing Caesarean delivery under general anaesthesia?

Evidence summary of apnoeic oxygenation - HFNO, LFNO
Author (Year)	Journal	Type of Article	Level of Evidence (AHA)	Intervention	Remarks	Supports Apnoeic Oxygenation
Osman YM (2021)[13]	Trends Anaesth Crit Care	Randomised controlled trial	B-R	HFNO (Preoxygenation + Apnoeic oxygenation, 30 to 50 L- Optiflow) vs face mask Preoxygenation (6 L 100 O2) + LFNO (6 LPM, nasal cannula, apnoeic oxygenation): for safe apnoea time	HFNO more effective than face mask+LFNO (6 L) in extending apnoea time	Yes
Patel S (2020)[32]	Curr Anesth Rep	Review article	C-LD	HFNO (10-15L)/Face mask: Preoxygenation plus apneic oxygenation (flow 10-15 L/min)	No clear data on HFNO for apnoeic oxygenation: Flow 10-15 L/min	Yes
Wong CA (2022)[35]	Br J Anaesth	Editorial	C-EO	Preoxygenation with face mask + LFNO (15 L after anaesthesia) vs HFNO preoxygenation + HFNO (50-70 L)	LFNO preferred due to practicality and adaptability, Concerns in obese and less availability of HFNO is an issue	Yes
Ellis R (2022)[14]	Br J Anaesth	Computational physiological model	C-EO	Preoxygenation with face mask followed by LFNO (nasal oxygen, 15 L/min) vs HFNO (70 L/min)	LFNO nearly equivalent safe apnoea time as HFNO	Yes
Stolady D (2021)[97]	Br J Anaesth	Computational physiological model	C-EO	Preoxygenation with face mask followed by no apenic oxygenation vs HFNO (70 L/min)	HFNO extends safe apnoea time in pregnant population	Yes
Murphy NE (2021)[98]	Int J Obstet Anesth	Editorial	C-EO	HFNO (preoxygenation + apnoeic oxygenation) vs Face mask preoxygenation	Though HFNO less effective in preoxygenation, may extend safe apnoea duration	Yes
Ramkumar V (2016)[7]	Indian J Anaesth	Guideline	C-EO	Preoxygenation plus LFNO (15 L/min)	LFNO recommended during apnoea till airway secured	Yes

RCT=Randomised controlled trial, HFNO=High flow nasal oxygenation, LFNO=Low flow nasal oxygenation, EtO₂=End-tidal oxygen concentration, THRIVE=Transnasal humidified rapid insufflation ventilatory exchange, LOE=Level of Evidence, AHA=American Heart Association, FiO₂=Fraction of inspired oxygen

APPENDIX 6

Research Question 7: What should be the antral volume measured by gastric ultrasound to minimise the risk of aspiration in full term parturient undergoing Caesarean delivery under GA?

Population: Pregnant women in labour and pregnant women for elective Caesarean delivery

Intervention: Gastric antral sonography

Comparator: None

Outcome:

Supplementary Table 6a.

Concept table for Research Question: What should be the antral volume measured by gastric ultrasound to minimise the risk of aspiration in full term parturient under going Caesarean delivery under GA?

	Concept 1	Concept 2	Concept 3	Concept 4	Concept 5	Concept 6
Key Concepts	Obstetric patients	Caesarean section/ Labour analgesia	Gastric ultrasound	Fasting guidelines	Aspiration risk	Perioperative period
Free Text Terms/ Natural Language Terms	pregnancy, pregnant women, parturients, obstetric women, maternal	cesarean delivery, c-section, labor analgesia, spinal for delivery, epidural labor, obstetric anesthesia	gastric ultrasonography, gastric point-of-care ultrasound, POCUS, ultrasound for gastric contents, gastric sono*, gastric antral scan	NPO, fasting status, preoperative fasting, traditional fasting guidelines,	aspiration pneumonia, pulmonary aspiration, gastric aspiration, regurgitation, Mendelson's syndrome, aspiration events	intraoperative, preoperative, during labor, during cesarean, during anesthesia,
Controlled Vocabulary/ MeSH Terms	“Pregnancy”[MeSH], “Obstetrics”[MeSH]	“Cesarean Section”[MeSH], “Anesthesia, Obstetrical”[MeSH], “Labor Pain”[MeSH]	“Ultrasonography”[MeSH], “Point-of-Care Systems”[MeSH], “Stomach/diagnostic imaging”[MeSH]	“Fasting”[MeSH], “Preoperative Care”[MeSH]	“Pulmonary Aspiration”[MeSH], “Aspiration Pneumonia”[MeSH]	“Perioperative Period”[MeSH], “Intraoperative Period”[MeSH], “Preoperative Period”[MeSH]

Search String:

PubMed (800 results) and Scopus (700 results)

((gastric antrum[MeSH Terms]) OR (gastric antral area[Title/Abstract])) OR (gastric volume[Title/Abstract])) OR (gastric emptying[MeSH Terms])) OR (gastric emptying[Title/Abstract])) OR (gastrointestinal contents[MeSH Terms])) OR (gastric contents[Title/Abstract])) OR (gastrointestinal content[MeSH Terms])) OR (gastric content[Title/Abstract])

((fasting[MeSH Terms]) OR (water[Title/Abstract])) OR (milk[Title/Abstract])) OR (tea[Title/Abstract])) OR (beverage[MeSH Terms])) ) OR (maltodextrin[Title/Abstract])) OR (orange juice[Title/Abstract])) OR (coffee[Title/ Abstract])) OR (drink, energy[MeSH Terms])) OR (carbohydrate[Title/Abstract])) OR (sports drink[Title/Abstract])

((pregnant women[MeSH Terms]) OR (pregnancy[Title/Abstract])) OR (third trimester pregnancy[Title/ Abstract])) OR (third trimester pregnant women[Title/Abstract])) OR (term pregnant women[Title/Abstract])) OR (parturients[Title/Abstract])) OR (labor[Title/Abstract])) OR (labour[Title/Abstract])

((diagnostic imaging MeSH Terms]) OR (ultrasound[Title/Abstract])) OR (ultrasonography[Title/Abstract])

((gastric antrum[MeSH Terms]) OR (gastric antral area[Title/Abstract])) OR (gastric volume[Title/Abstract])) OR (gastric emptying[MeSH Terms])) OR (gastric emptying[Title/Abstract])) OR (gastrointestinal contents[MeSH Terms])) OR (gastric contents[Title/Abstract])) OR (gastrointestinal content[MeSH Terms])) OR (gastric content[Title/Abstract]) AND ((fasting[MeSH Terms]) OR (water[Title/Abstract])) OR (milk[Title/Abstract])) OR (tea[Title/Abstract])) OR (beverage[MeSH Terms])) ) OR (maltodextrin[Title/Abstract])) OR (orange juice[Title/ Abstract])) OR (coffee[Title/Abstract])) OR (drink, energy[MeSH Terms])) OR (carbohydrate[Title/Abstract])) OR (sports drink[Title/Abstract]) AND ((pregnant women[MeSH Terms]) OR (pregnancy[Title/Abstract])) OR (third trimester pregnancy[Title/Abstract])) OR (third trimester pregnant women[Title/Abstract])) OR (term pregnant women[Title/Abstract])) OR (parturients[Title/Abstract])) OR (labor[Title/Abstract])) OR (labour[Title/Abstract]) AND ((diagnostic imaging[MeSH Terms]) OR (ultrasound[Title/Abstract])) OR (ultrasonography[Title/Abstract])

Supplementary Figure 6

PRISMA flow chart for Research Question: What should be the antral volume measured by gastric ultrasound to minimise the risk of aspiration in full term parturient under going Caesarean delivery under GA?

Supplementary Table 6b.

Summary table for included studies for Research Question: What should be the antral volume measured by gastric ultrasound to minimise the risk of aspiration in full term parturient under going Caesarean delivery under GA?

Gastric sonography in pregnancy - Criteria for full stomach
Author (Year)	Journal	Type of Article	Level of Evidence (AHA)	Intervention	Conclusion
Harnett (2024)[26]	Eur J Anaesthesiol	Prospective observational	B-NR	USG; CSA comparison between fasting vs sip-till-send; Elective CD	CSA ≥1.5 mL/kg indicates risk; “Sip till send” before CS as effective as standard fasting
Desgranges (2022)[100]	Acta Anaesthesiol Scand	Prospective observational	B-NR	USG; >1.5 mL/kg risk; to identify cutoff CSA	CSA ≥393 mm2 predicts risk;
Chang (2022)[101]	BMC Anesthesiol	Cross-sectional study	B-NR	USG; labouring vs non-labouring CSA	Higher risk stomach in labouring group; USG recommended if GA needed
Sarhan (2021)[102]	J Anesth	Prospective observational	B-NR	USG; CSA after 8h fasting in non-labouring term	Low risk after 8h fast; USG useful
Van de Putte (2019)[103]	Br J Anaesth	Prospective cohort	B-NR	USG; baseline CSA in fasting term parturients	CSA in healthy fasting non laboring pregnant patient- 8.7 cm2 ≈ 1.4 mL/kg
Amaral (2019)[104]	Braz J Anesthesiol	Prospective cohort	B-NR	Antral CSA estimation and correlation with demography and clinical characteristics	CSA correlates with BMI; USG supports risk assessment
Popivanov (2020) [105]	Int J Obstet Anesth	Prospective observational	B-NR	USG; CSA post-CHO drink fasting protocol	400mL CHO safe up to 2h pre-op; USG useful
Arzola (2018)[27]	Anaesthesia	RCT	B-R	Relation of CSA with fluid volume; to detect ingested volume equal to 1.5ml/kg	CSA ≥9.6 cm2= ≥1.5 mL/kg; USG useful
Perlas (2018)[106]	Can J Anaesth	Narrative review	C-EO	Review; CSA correlation with aspiration risk	CSA ≥9.6 cm2=high volume; supports USG
Van de Putte (2018)[107]	Anaesthesia	Editorial	C-EO	Editorial on CSA thresholds and solids	CSA 9-10 cm2=1.5 mL/kg; solids invalidate fasting status
Roukhomovsky (2018)[22]	Eur J Anaesthesiol	Prospective cohort	B-NR	USG vs MRI; CSA for fluid volume	CSA≥505 mm2 predicts >1.5 mL/kg; USG useful
Hakak (2021)[22]	Int J Obstet Anesth	Prospective observational	B-NR	USG; CSA to assess solid content after 6h fasting	37.5% had >1.5 mL/kg; USG detects risk despite fasting
Jay (2020)[108]	Eur J Anaesthesiol	Prospective cohort	B-NR	USG; CSA in supine during labour	CSA ≤381 mm2=empty; USG useful in emergencies
Zieleskiewicz (2020)[28]	Br J Anaesth	Prospective observational	B-NR	USG; CSA cutoffs for 0.4/0.8/1.5 mL/kg	CSA 387-608 mm2 for thresholds; supports USG stratification

USG=Ultrasonography, CSA=Cross-sectional area, CD=Caesarean delivery, CHO=Carbohydrate, MRI=Magnetic resonance imaging, RCT=Randomised controlled trial, AHA=American Heart Association

APPENDIX 7

Research Question 8: What is the adequate fasting time for liquids and solids in pregnant women in labour and pregnant women for elective Caesarean delivery?

Population: Pregnant women in labour and pregnant women for elective Caesarean delivery Intervention: Gastric antral sonography Comparator: None

Supplementary Table 7a.

Concept table for Research Question: What is the adequate fasting time for liquids and solids in pregnant women in labour and pregnant women for elective Caesarean delivery?

	Concept 1	Concept 2	Concept 3	Concept 4	Concept 5	Concept 6
Key Concepts	Obstetric patients	Cesarean section/ Labor analgesia	Gastric ultrasound	Fasting guidelines	Aspiration risk	Perioperative period
Free Text Terms/Natural Language Terms	pregnancy, pregnant women, parturients, obstetric women, maternal	cesarean delivery, c-section, labor analgesia, spinal for delivery, epidural labor, obstetric anesthesia	gastric ultrasonography, gastric point-of-care ultrasound, POCUS, ultrasound for gastric contents, gastric sono*, gastric antral scan	NPO, fasting status, preoperative fasting, traditional fasting guidelines,	aspiration pneumonia, pulmonary aspiration, gastric aspiration, regurgitation, Mendelson's syndrome, aspiration events	intraoperative, preoperative, during labor, during cesarean, during anesthesia,
Controlled Vocabulary/ MeSH Terms	“Pregnancy”[MeSH], “Obstetrics”[MeSH]	“Cesarean Section”[MeSH], “Anesthesia, Obstetrical”[MeSH], “Labor Pain”[MeSH]	“Ultrasonography”[MeSH], “Point-of-Care Systems”[MeSH], “Stomach/diagnostic imaging”[MeSH]	“Fasting”[MeSH], “Preoperative Care”[MeSH]	“Pulmonary Aspiration”[MeSH], “Aspiration Pneumonia”[MeSH]	“Perioperative Period”[MeSH], “Intraoperative Period”[MeSH], “Preoperative Period”[MeSH]

Search String:

PubMed (800 results) and Scopus (700 results)

((gastric antrum[MeSH Terms]) OR (gastric antral area[Title/Abstract])) OR (gastric volume[Title/Abstract])) OR (gastric emptying[MeSH Terms])) OR (gastric emptying[Title/Abstract])) OR (gastrointestinal contents[MeSH Terms])) OR (gastric contents [Title/Abstract])) OR (gastrointestinal content[MeSH Terms])) OR (gastric content[Title/Abstract])

((fasting[MeSH Terms]) OR (water[Title/Abstract])) OR (milk[Title/Abstract])) OR (tea[Title/Abstract])) OR (beverage[MeSH Terms])) ) OR (maltodextrin[Title/Abstract])) OR (orange juice[Title/Abstract])) OR (coffee[Title/ Abstract])) OR (drink, energy[MeSH Terms])) OR (carbohydrate[Title/Abstract])) OR (sports drink[Title/Abstract])

((pregnant women[MeSH Terms]) OR (pregnancy[Title/Abstract])) OR (third trimester pregnancy[Title/ Abstract])) OR (third trimester pregnant women[Title/Abstract])) OR (term pregnant women[Title/Abstract])) OR (parturients[Title/Abstract])) OR (labor[Title/Abstract])) OR (labour[Title/Abstract])

((diagnostic imaging MeSH Terms]) OR (ultrasound[Title/Abstract])) OR (ultrasonography[Title/Abstract])

((gastric antrum[MeSH Terms]) OR (gastric antral area[Title/Abstract])) OR (gastric volume[Title/Abstract])) OR (gastric emptying[MeSH Terms])) OR (gastric emptying[Title/Abstract])) OR (gastrointestinal contents[MeSH Terms])) OR (gastric contents[Title/Abstract])) OR (gastrointestinal content[MeSH Terms])) OR (gastric content[Title/Abstract]) AND ((fasting[MeSH Terms]) OR (water[Title/Abstract])) OR (milk[Title/Abstract])) OR (tea[Title/Abstract])) OR (beverage[MeSH Terms])) ) OR (maltodextrin[Title/Abstract])) OR (orange juice[Title/ Abstract])) OR (coffee[Title/Abstract])) OR (drink, energy[MeSH Terms])) OR (carbohydrate[Title/Abstract])) OR (sports drink[Title/Abstract]) AND ((pregnant women[MeSH Terms]) OR (pregnancy[Title/Abstract])) OR (third trimester pregnancy[Title/Abstract])) OR (third trimester pregnant women[Title/Abstract])) OR (term pregnant women[Title/Abstract])) OR (parturients[Title/Abstract])) OR (labor[Title/Abstract])) OR (labour[Title/Abstract]) AND ((diagnostic imaging[MeSH Terms]) OR (ultrasound[Title/Abstract])) OR (ultrasonography[Title/Abstract])

Supplementary Figure 7

PRISMA flow chart for Research Question: What is the adequate fasting time for liquids and solids in pregnant women in labour and pregnant women for elective Caesarean delivery?

Supplementary Table 7b.

Summary table for included studies for Research Question: What is the adequate fasting time for liquids and solids in pregnant women in labour and pregnant women for elective Caesarean delivery?

Fasting duration in pregnancy - Liquids and solids
Author (Year)	Journal	Type of Article	Level of Evidence (AHA)	Intervention	Conclusion
Harnett[26] (2024)	Eur J Anaesthesiol	Prospective observational	B-NR	CSA comparison between full fast vs sip-till-send; gastric volume, Perlas grading	Sip-till-send' similar to standard fasting; >1.5 mL/kg used as aspiration risk threshold
Bouvet[109] (2024)	Anaesth Crit Care Pain Med	Editorial	C-EO	Fasting policies in labour; guidelines comparison (France vs USA)	Clear liquids up to 2h; light meals up to 6h; restrictive in labour in US guideline vs French guideline
Bouvet[110] (2022)	Anesthesiology	RCT	B-R	Gastric CSA at 15 and 90 mins after light meal	Gastric emptying is delayed, Labour analgesia facilitates gastric emptying after light meal
Chang[101] (2022)	BMC Anesthesiol	Cross-sectional	C-LD	CSA comparison in labouring vs non-labouring women	Higher risk stomach in labouring group; recommend USG if GA needed
Sarhan[102] (2022)	J Anesth	Prospective observational	B-NR	Proportion with gastric volume >1.5 mL/kg after 8h fast	Low gastric volume after 8h fast with standardised meal
Irwin[24] (2020)	Eur J Anaesthesiol	RCT	B-R	CSA after 250 mL tea with milk vs 250 mL water at 120 minutes	Similar gastric emptying; modest milk intake safe up to 2h pre-op
Van de Putte[103] (2019)	Br J Anaesth	Prospective cohort	B-NR	CSA and gastric fluid volume in fasting term non-labouring women	CSA 8.7 cm2 ≈ 1.4 mL/kg; no significant difference from non-pregnant
Popivanov [105] (2020)	Int J Obstet Anesth	Prospective observational	B-NR	CSA return to fasted grade (0 or 1) post CHO drink	400 mL CHO safe up to 2h before elective surgery
Nascimento[23] (2019)	Anaesthesia	RCT	B-R	Gastric emptying of maltodextrin, coffee with milk, orange juice (pulp free)	Maltodextrin cleared fastest; 90-120 mins needed for other drinks
Hakak[22] (2018)	Int J Obstet Anesth	Prospective observational	B-NR	Presence of solids after 6h fasting	No solids, but residual volumes in many; fasting guidelines may need revision
Desgranges[100] (2019)	Acta Anaesthesiol Scand	Prospective observational	B-NR	SR-CSA in women with epidural and allowed fluids	25% had>1.5 mL/kg at full dilation; SR-CSA may aid in urgent assessment
Ng[111] (2024)	Am J Obstet Gynecol	RCT	B-R	Free water access vs midnight fasting; outcome: vomiting and satisfaction	Free water reduced vomiting, preferred by women

CSA=Cross-sectional area, USG=Ultrasonography, CD=Caesarean delivery, CHO=Carbohydrate, SR-CSA=Semi-recumbent cross-sectional area, RCT=Randomised controlled trial, AHA=American Heart Association

APPENDIX 8

Research Question 9: If face mask ventilation is successful, can it be considered safe and feasible to continue the anaesthetic and deliver baby without proceeding to tracheal intubation?

• Population - Parturients at term pregnancy undergoing Caesarean delivery under general anaestheia

• Intervention - Face mask ventilation

• Control or comparison - Tracheal intubation

• Outcome - Maternal and fetal safety

Supplementary Table 8a.

Concept table for Research Question: If face mask ventilation is successful, can it be considered safe and feasible to continue the anaesthetic and deliver baby without proceeding to tracheal intubation?

Research Question	Concept 1	Concept 2	Concept 3	Concept 4	Concept 5	Concept 6
Key concepts Free text terms/natural language terms (synonyms, UK/US terminology, medical/ laymen's terms, acronyms/ abbreviations, drug brands, more narrow search terms) Consider: phrase searching, proximity operators, truncation, wildcards, field qualification (e.g. textword)	Pregnancy pregnancies; pregnant; normal pregnancy; pregnancy normal; pregnan*	Parturient Parturient Parturitions last trimester. Pregnancy Trimester, Third Third Pregnancy Trimester Third Pregnancy Trimesters Pregnancy, Third Trimester Pregnancies, Third Trimester Third Trimester Pregnancies Third Trimester Pregnancy Trimester, Third Third Trimester Third Trimesters Trimesters, Third Last Trimester Last Trimesters Trimester, Last Trimesters, Last	Cesarean Cesarean surgery; emergency Cesarean delivery; Elective cesarean delivery; Caesarean surgery; emergency Caesarean delivery; Elective caesarean delivery; obstetric surgeries; obstetric surgery Cesarean Section/ methods* Caesarean delivery Cesarean Sections Abdominal Delivery C-Sections (OB) Caesarean Section Caesarean Sections Delivery, Abdominal Abdominal Deliveries Deliveries, Abdominal Postcesarean Section Deliveries, Obstetric Obstetric Deliveries Obstetric Delivery	GA Anesthesia, General/ methods* Anesthesia* Anesthesia, Obstetrical/methods* Anesthesia, Obstetrical* Anesthesias, General General Anesthesia General Anesthesias	Ventilation (“ventilated” [All Fields] OR “ventilates” [All Fields] OR “ventilating” [All Fields] OR “ventilation” [All Fields] OR “ventilate” [All Fields] OR “ventilations” [All Fields] OR “ventilator s” [All Fields] OR (“ventilators” [All Fields] AND “mechanical” [All Fields]) OR “mechanical ventilators” [All Fields] OR “ventilator” [All Fields] OR “ventilators” [All Fields] OR “ventillation” [All Fields])	Intubation “intubate” [All Fields] OR “intubated” [All Fields] OR “intubates” [All Fields] OR “intubating” [All Fields] OR “intubation” [MeSH Terms] OR “intubation” [All Fields] OR “intubations” [All Fields] OR “intubator” [All Fields] OR “intubators” [All Fields] OR “intubators” [All Fields]
Controlled vocabulary terms/Subject terms (MeSH terms, Emtree terms) Consider: explode, major headings, subheadings	Pregnancy	“Term Birth”[Mesh] “Pregnancy Trimester, Third”[Mesh]	Cesarean Section “Cesarean Section”[Mesh] “Cesarean Section”[Mesh: NoExp] “Cesarean Section, Repeat”[Mesh: NoExp]	“Anesthetics, General”[Mesh] “Anesthesia”[Mesh] “Anesthesia, Obstetrical”[Mesh]	“ventilation”[MeSH Terms] ventilators, mechanical”[MeSH Terms]	“Intubation, Intratracheal” [Mesh]

Search String:

PubMed: 75 results

(((("Parturient"[Title/Abstract] OR "Parturitions" [Title/Abstract] OR "Last Trimester" [Title/Abstract] OR "pregnancy trimester third"[Title/Abstract] OR "Third Pregnancy Trimester"[Title/Abstract] OR "Third Pregnancy Trimesters"[Title/Abstract] OR "pregnancy third trimester"[Title/Abstract] OR "pregnancies third trimester"[Title/ Abstract] OR "Third Trimester Pregnancies"[Title/Abstract] OR "Third Trimester Pregnancy"[Title/Abstract] OR "trimester third"[Title/Abstract] OR "Third Trimester"[Title/Abstract] OR "Third Trimesters"[Title/Abstract] OR "trimesters third" [Title/Abstract] OR "Last Trimester" [Title/Abstract] OR "Last Trimesters" [Title/Abstract] OR "trimester last"[Title/Abstract] OR "Term Birth"[MeSH Terms] OR "pregnancy trimester, third"[MeSH Terms]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans"[MeSH Terms] AND 2000/01/01:2024/12/31[Date - Publication] AND "english"[Language])) OR ((("pregnancies" [Title/Abstract] OR "pregnant" [Title/Abstract] OR "normal pregnancy" [Title/Abstract] OR "pregnancy normal"[Title/Abstract] OR "pregnan*"[Title/Abstract] OR "pregnancy"[MeSH Terms]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans"[MeSH Terms] AND 2000/01/01:2024/12/31[Date - Publication] AND "english"[Language])) OR (("Cesarean surgery"[Title/Abstract] OR "emergency Cesarean delivery"[Title/Abstract] OR "Elective cesarean delivery"[Title/Abstract] OR "Caesarean surgery"[Title/Abstract] OR "emergency Caesarean delivery"[Title/Abstract] OR "Elective caesarean delivery"[Title/ Abstract] OR "obstetric surgeries"[Title/Abstract] OR "obstetric surgery"[Title/Abstract] OR "cesarean section methods"[Title/Abstract] OR "Caesarean delivery"[Title/Abstract] OR "Cesarean Sections"[Title/Abstract] OR "Abdominal Delivery"[Title/Abstract] OR "c sections ob"[Title/Abstract] OR "Caesarean Section"[Title/Abstract] OR "Caesarean Sections"[Title/Abstract] OR "delivery abdominal"[Title/Abstract] OR "Abdominal Deliveries"[Title/ Abstract] OR "deliveries abdominal"[Title/Abstract] OR "Postcesarean Section"[Title/Abstract] OR "deliveries obstetric"[Title/Abstract] OR "Obstetric Deliveries"[Title/Abstract] OR "Obstetric Delivery"[Title/Abstract] OR "Cesarean Section"[MeSH Terms] OR "Cesarean Section"[MeSH Terms:noexp] OR "cesarean section, repeat"[MeSH Terms:noexp]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans" [MeSH Terms] AND 2000/01/01:2024/12/31[Date - Publication] AND "english"[Language])))) AND (("anesthesia general methods"[Title/Abstract] OR "anesthesia*"[Title/Abstract] OR "anesthesia obstetrical"[Title/Abstract] OR "General Anesthesia"[Title/Abstract] OR "General Anesthesias"[Title/ Abstract] OR "anesthetics, general"[MeSH Terms] OR "Anesthesia"[MeSH Terms] OR "anesthesia, obstetrical"[MeSH Terms]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans"[MeSH Terms] AND 2000/01/01:2024/12/31[Date - Publication] AND "english"[Language])) AND (("intubate"[All Fields] OR "intubated" [All Fields] OR "intubates"[All Fields] OR "intubating" [All Fields] OR "intubation"[MeSH Terms] OR "intubation"[All Fields] OR "intubations"[All Fields] OR "intubator"[All Fields] OR "intubator s"[All Fields] OR "intubators"[All Fields] OR "intubation, intratracheal" [MeSH Terms]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans"[MeSH Terms] AND 2000/01/01:2024/12/31[Date - Publication] AND "english"[Language])) AND (("ventilated"[All Fields] OR "ventilates"[All Fields] OR "ventilating"[All Fields] OR "ventilation"[MeSH Terms] OR "ventilation"[All Fields] OR "ventilate"[All Fields] OR "ventilations"[All Fields] OR "ventilator s"[All Fields] OR "ventilators, mechanical"[MeSH Terms] OR ("ventilators"[All Fields] AND "mechanical"[All Fields]) OR "mechanical ventilators"[All Fields] OR "ventilator"[All Fields] OR "ventilators"[All Fields] OR "ventillation"[All Fields]) AND ("humans"[MeSH Terms] AND 2000/01/01:2024/12/31[Date - Publication] AND "english"[Language]))) AND ((humans[Filter]) AND (2000:2024[pdat]) AND (english[Filter]))

Scopus: 48 results

( TITLE-ABS ( "caesarean" OR "cesarean" OR "parturient" ) AND TITLE-ABS ( "general anesthesia" OR "general anaesthesia" ) AND TITLE-ABS ( "ventilation" OR "ventilator" OR "mechanical ventilation" ) AND TITLE-ABS ( "intubation" OR "intubated" OR "intubate" ) ) AND PUBYEAR > 1999 AND PUBYEAR < 2025 AND LANGUAGE ( "English" )

Supplementary Figure 8

PRISMA flow chart for Research Question: If face mask ventilation is successful, can it be considered safe and feasible to continue the anaesthetic and deliver baby without proceeding to tracheal intubation?

Supplementary Table 8b.

Summary table for included studies for Research Question: If face mask ventilation is successful, can it be considered safe and feasible to continue the anaesthetic and deliver baby without proceeding to tracheal intubation?

Evidence summary for continuation for the face mask ventilation in situation of intubation failure
Author (Year)	Journal	Type of Article	Level of Evidence (AHA)	Intervention	Remarks	Supports Research Question
Sklebar I (2023)[112]	Acta Clin Croat	Review	C-LD	Wake patient if ventilation fails	Emphasises need for modern airway algorithms but does not support continuation if ventilation is in doubt	Not sure
Asai T (2015)[113]	J Anesth	Review	C-LD	Wake up if intubation fails	Recommends rapid wake-up; discusses risk but not alternative continuation	Not sure
Mushambi MC (2016)[114]	Curr Opin Anaesthesiol	Review	C-LD	Assess continuation vs wake-up	Describes evolving standards and planning for post-intubation failure decisions	Indirect Support
Ezri T (2001)[115]	Obstet Gynecol Surv	Review	C-LD	Continue with mask or LMA	Advocates for mask or LMA use in failed intubation situations	Yes
Tao W (2012)[116]	J Anesth	Retrospective Study	B-NR	Used face mask or LMA to ventilate successfully	Real-world cases show successful continuation without complications	Yes
Mushambi MC (2015)[84]	Anaesthesia	Guideline	C-EO	Continue if safe; use second-generation SAD	UK guideline supports continuation if airway is secured with mask or SAD	Yes
Ramkumar V (2016)[7]	Indian J Anaesth	Guideline	C-EO	Continue with SAD or mask ventilation if feasible	Indian guidelines support safe continuation, especially with appropriate equipment and expertise	Yes

LOE=Level of Evidence, RCT=Randomised controlled trial, LMA=Laryngeal mask airway, SAD=Supraglottic airway device, UK=United Kingdom, EO=Expert opinion

APPENDIX 9

Research Question 10: In parturient undergoing Caesarean delivery under general anaesthesia with rapid sequence induction, is it safe to allow gentle face mask ventilation and release cricoid force if difficulty with ventilation or intubation encountered?

• Population - Parturients at term pregnancy undergoing Caesarean delivery under general anaesthesia

• Intervention - Modified RSI (application of cricoid force and the timing and manner of its release); (b) gentle face mask ventilation with APL valve kept at or below 20 cm H20)

• Control or comparison - Conventional RSI (preoxygenation using face mask with cricoid pressure)

• Outcome - Desaturation regurgitation, vomiting, aspiration, stomach inflation, Mendelson syndrome, Pneumonia, ARDS

Supplementary Table 9a.

Concept table for Research Question: In parturient undergoing Caesarean delivery under general anaesthesia with rapid sequence induction, is it safe to allow gentle face mask ventilation and release cricoid force if difficulty with ventilation or intubation encountered?

Research Question	Concept 1	Concept 2	Concept 3	Concept 4	Concept 5	Concept 6	Concept 7	Concept 8
Key concepts	Pregnancy	Term pregnancy	Cesarean	GA	Modified//rapid sequence induction	cricoid force	face-mask ventilation	Desaturation
Free text terms/natural language terms (synonyms, UK/US terminology, medical/ laymen’s terms, acronyms/ abbreviations, drug brands, more narrow search terms) Consider: phrase searching, proximity operators, truncation, wildcards, field qualification (e.g. textword)	pregnancies; pregnant; normal pregnancy; pregnancy normal; pregnan*	Parturient Parturitions last trimester. Pregnancy Trimester, Third Third Pregnancy Trimester Third Pregnancy Trimesters Pregnancy, Third Trimester Pregnancies, Third Trimester Third Trimester Pregnancies Third Trimester Pregnancy Trimester, Third Third Trimester Third Trimesters Trimesters, Third Last Trimester Last Trimesters Trimester, Last Trimesters, Last	Cesarean surgery; emergency Cesarean delivery; Elective cesarean delivery; Caesarean surgery; emergency Caesarean delivery; Elective caesarean delivery; obstetric surgeries; obstetric surgery Cesarean Section/ methods* Caesarean delivery Cesarean Sections Abdominal Delivery C-Sections (OB) Caesarean Section Caesarean Sections Delivery, Abdominal Abdominal Deliveries Deliveries, Abdominal Postcesarean Section Deliveries, Obstetric Obstetric Deliveries Obstetric Delivery	Anesthesia, General/ methods* Anesthesia* Anesthesia, Obstetrical/ methods* Anesthesia, Obstetrical* Anesthesias, General General Anesthesia General Anesthesias	(“modified rapid sequence induction” [All Fields] OR “modified rapid sequence intubation” [All Fields] OR “rapid sequence induction” [All Fields] OR “rapid sequence induction and” [All Fields] OR “rapid sequence induction and intubation” [All Fields] OR “rapid sequence induction and intubation adverse” [All Fields] OR “rapid sequence induction and intubation adverse effects” [All Fields] OR “rapid sequence induction and intubation instrumentation” [All Fields] OR “rapid sequence induction and intubation methods” [All Fields] OR “rapid sequence induction and intubation mortality” [All Fields] OR “rapid sequence induction and intubation rsii” [All Fields] OR “rapid sequence induction and intubation standards” [All Fields] OR “rapid sequence induction and intubation statistics” [All Fields] OR “rapid sequence induction and intubation statistics and” [All Fields] OR “rapid sequence induction and intubation statistics and numerical” [All Fields] OR “rapid sequence induction and intubation statistics and numerical data” [All Fields] OR “rapid sequence induction group” [All Fields] OR “rapid sequence induction intubation” [All Fields] OR “rapid sequence induction orotracheal” [All Fields] OR “rapid sequence induction orotracheal intubation” [All Fields] OR “rapid sequence induction procedure” [All Fields] OR “rapid sequence induction protocol” [All Fields] OR “rapid sequence induction regimen” [All Fields] OR “rapid sequence induction rsi” [All Fields] OR “rapid sequence induction technique” [All Fields]	(“cricoid force”[All Fields] OR “cricoid force application”[All Fields] OR “cricoid forces”[All Fields] OR “cricoid pressure application”[All Fields] OR “cricoid pressure decreases”[All Fields] OR “cricoid pressure force”[All Fields] OR “cricoid pressure group”[All Fields] OR “cricoid pressure induced”[All Fields] OR “cricoid pressure induced relaxation”[All Fields] OR “cricoid pressure maneuver”[All Fields] OR “cricoid pressure maneuvers”[All Fields] OR “cricoid pressure providers”[All Fields] OR “cricoid pressure simulator”[All Fields] OR “cricoid pressure trainer”[All Fields] OR “cricoid pressure training”[All Fields]) AND ((humans[Filter]) AND (english[Filter])) (“sellick s maneuver”[All	(“face mask ventilation”[All Fields]) (“positive pressure ventilation”[All Fields] OR “positive pressure ventilation devices”[All Fields]) AND ((humans[Filter]) AND (english[Filter]))	“oxygen desaturation”[All Fields] OR “oxygen desaturation criteria”[All Fields] OR “oxygen desaturation duration”[All Fields]) AND ((humans[Filter]) AND (english[Filter]))
Key concepts	Pregnancy	Term pregnancy	Cesarean	GA	Modified//rapid sequence induction OR “rapid sequence induction techniques” [All Fields] OR “rapid sequence inductions” [All Fields] OR “rapid sequence intubation” [All Fields] OR “rapid sequence intubation agents” [All Fields] OR “rapid sequence intubation cases” [All Fields] OR “rapid sequence intubation induction” [All Fields] OR “rapid sequence intubation medications” [All Fields] OR “rapid sequence intubation method” [All Fields] OR “rapid sequence intubation protocol” [All Fields] OR “rapid sequence intubation protocols” [All Fields] OR “rapid sequence intubation rsi” [All Fields] OR “rapid sequence intubation rsi pre” [All Fields] OR “rapid sequence intubation short acting” [All Fields] OR “rapid sequence intubation technique” [All Fields] OR “rapid sequence intubations” [All Fields]) AND ((humans[Filter]) AND (english[Filter]))	cricoid force Fields] OR “sellick s manoeuvre”[All Fields] OR “sellick manoeuvre”[All Fields] OR “sellick manover”[All Fields]) AND ((humans[Filter]) AND (english[Filter])) (“BURP”[All Fields]) AND ((humans[Filter]) AND (english[Filter])) (“OELM”[All Fields]) AND ((humans[Filter]) AND (english[Filter]))	face-mask ventilation	Desaturation
Controlled vocabulary terms / Subject terms (MeSH terms, Emtree terms) Consider: explode, major headings, subheadings	Pregnancy	“Term Birth”[Mesh] “Pregnancy Trimester, Third”[Mesh]	Cesarean Section "Cesarean Section" [Mesh] "Cesarean Section" [Mesh:NoExp] "Cesarean Section, Repeat" [Mesh:NoExp]	“Anesthetics, General” [Mesh] “Anesthesia” [Mesh] “Anesthesia, Obstetrical” [Mesh]

Search String:

PubMed: 69 results

(((("Parturient"[Title/Abstract] OR "Parturitions" [Title/Abstract] OR "Last Trimester" [Title/Abstract] OR "pregnancy trimester third"[Title/Abstract] OR "Third Pregnancy Trimester"[Title/Abstract] OR "Third Pregnancy Trimesters"[Title/Abstract] OR "pregnancy third trimester"[Title/Abstract] OR "pregnancies third trimester"[Title/ Abstract] OR "Third Trimester Pregnancies"[Title/Abstract] OR "Third Trimester Pregnancy"[Title/Abstract] OR "trimester third"[Title/Abstract] OR "Third Trimester"[Title/Abstract] OR "Third Trimesters"[Title/Abstract] OR "trimesters third" [Title/Abstract] OR "Last Trimester" [Title/Abstract] OR "Last Trimesters" [Title/Abstract] OR "trimester last"[Title/Abstract] OR "Term Birth"[MeSH Terms] OR "pregnancy trimester, third"[MeSH Terms]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans"[MeSH Terms] AND "english"[Language])) OR (("Cesarean surgery"[Title/Abstract] OR "emergency Cesarean delivery"[Title/Abstract] OR "Elective cesarean delivery"[Title/Abstract] OR "Caesarean surgery"[Title/ Abstract] OR "emergency Caesarean delivery"[Title/Abstract] OR "Elective caesarean delivery"[Title/Abstract] OR "obstetric surgeries"[Title/Abstract] OR "obstetric surgery"[Title/Abstract] OR "cesarean section methods"[Title/ Abstract] OR "Caesarean delivery"[Title/Abstract] OR "Cesarean Sections"[Title/Abstract] OR "Abdominal Delivery"[Title/Abstract] OR "c sections ob"[Title/Abstract] OR "Caesarean Section"[Title/Abstract] OR "Caesarean Sections"[Title/Abstract] OR "delivery abdominal"[Title/Abstract] OR "Abdominal Deliveries"[Title/Abstract] OR "deliveries abdominal"[Title/Abstract] OR "Postcesarean Section"[Title/Abstract] OR "deliveries obstetric"[Title/Abstract] OR "Obstetric Deliveries"[Title/Abstract] OR "Obstetric Delivery"[Title/Abstract] OR "Cesarean Section"[MeSH Terms] OR "Cesarean Section"[MeSH Terms:noexp] OR "cesarean section, repeat"[MeSH Terms:noexp]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans"[MeSH Terms] AND "english"[Language]))) AND (("anesthesia general methods"[Title/Abstract] OR "anesthesia*"[Title/Abstract] OR "anesthesia obstetrical"[Title/Abstract] OR "General Anesthesia"[Title/Abstract] OR "General Anesthesias"[Title/Abstract] OR "anesthetics, general"[MeSH Terms] OR "Anesthesia"[MeSH Terms] OR "anesthesia, obstetrical"[MeSH Terms]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans"[MeSH Terms] AND "english"[Language])) AND ((("modified rapid sequence induction"[All Fields] OR "modified rapid sequence intubation"[All Fields] OR "rapid sequence induction"[All Fields] OR "rapid sequence induction and"[All Fields] OR "rapid sequence induction and intubation"[All Fields] OR "rapid sequence induction and intubation adverse"[All Fields] OR "rapid sequence induction and intubation adverse effects"[All Fields] OR "rapid sequence induction and intubation instrumentation"[All Fields] OR "rapid sequence induction and intubation methods"[All Fields] OR "rapid sequence induction and intubation mortality"[All Fields] OR "rapid sequence induction and intubation rsii"[All Fields] OR "rapid sequence induction and intubation standards"[All Fields] OR "rapid sequence induction and intubation statistics"[All Fields] OR "rapid sequence induction and intubation statistics and"[All Fields] OR "rapid sequence induction and intubation statistics and numerical"[All Fields] OR "rapid sequence induction and intubation statistics and numerical data"[All Fields] OR "rapid sequence induction group"[All Fields] OR "rapid sequence induction intubation" [All Fields] OR "rapid sequence induction orotracheal" [All Fields] OR "rapid sequence induction orotracheal intubation"[All Fields] OR "rapid sequence induction procedure"[All Fields] OR "rapid sequence induction protocol"[All Fields] OR "rapid sequence induction regimen"[All Fields] OR "rapid sequence induction rsi"[All Fields] OR "rapid sequence induction technique"[All Fields] OR "rapid sequence induction techniques"[All Fields] OR "rapid sequence inductions"[All Fields] OR "rapid sequence intubation"[All Fields] OR "rapid sequence intubation agents"[All Fields] OR "rapid sequence intubation cases"[All Fields] OR "rapid sequence intubation induction"[All Fields] OR "rapid sequence intubation medications"[All Fields] OR "rapid sequence intubation method"[All Fields] OR "rapid sequence intubation protocol"[All Fields] OR "rapid sequence intubation protocols"[All Fields] OR "rapid sequence intubation rsi"[All Fields] OR "rapid sequence intubation rsi pre"[All Fields] OR "rapid sequence intubation short acting"[All Fields] OR "rapid sequence intubation technique" [All Fields] OR "rapid sequence intubations" [All Fields]) AND ("humans" [MeSH Terms] AND "english"[Language]) AND 2000/01/01:2024/12/31[Date - Publication] AND ("humans"[MeSH Terms] AND "english" [Language])) OR (((("cricoid force"[All Fields] OR "cricoid force application" [All Fields] OR "cricoid forces"[All Fields] OR "cricoid pressure application"[All Fields] OR "cricoid pressure decreases"[All Fields] OR "cricoid pressure force"[All Fields] OR "cricoid pressure group"[All Fields] OR "cricoid pressure induced"[All Fields] OR "cricoid pressure induced relaxation"[All Fields] OR "cricoid pressure maneuver"[All Fields] OR "cricoid pressure maneuvers"[All Fields] OR "cricoid pressure providers"[All Fields] OR "cricoid pressure simulator"[All Fields] OR "cricoid pressure trainer"[All Fields] OR "cricoid pressure training"[All Fields]) AND ("humans"[MeSH Terms] AND "english"[Language])) OR ("sellick s maneuver"[All Fields] OR "sellick s manoeuvre"[All Fields] OR "sellick manoeuvre"[All Fields] OR "sellick manover"[All Fields]) OR "BURP"[All Fields] OR "OELM"[All Fields]) AND 2000/01/01:2024/12/31[Date - Publication] AND ("humans"[MeSH Terms] AND "english"[Language])))) AND ((humans[Filter]) AND (english[Filter]))

Scopus : 150 results

( TITLE-ABS-KEY ( "Cesarean surgery" OR "emergency Cesarean delivery" OR "Elective cesarean delivery" OR "Caesarean surgery" OR "emergency Caesarean delivery" OR "Elective caesarean delivery" OR "obstetric surgeries" OR "obstetric surgery" OR "cesarean section methods" OR "Caesarean delivery" OR "Cesarean Sections" OR "Abdominal Delivery" OR "c sections ob" OR "Caesarean Section" OR "Caesarean Sections" OR "delivery abdominal" OR "Abdominal Deliveries" OR "deliveries abdominal" OR "Postcesarean Section" OR "deliveries obstetric" OR "Obstetric Deliveries" OR "Obstetric Delivery" OR "Cesarean Section" OR "cesarean section, repeat" ) ) AND ( TITLE- ABS-KEY ( "anesthesia general methods" OR "anesthesia*" OR "anesthesia obstetrical" OR "General Anesthesia" OR "General Anesthesias" OR "anesthetics, general" OR "Anesthesia" OR "anesthesia, obstetrical" ) ) AND ( TITLE- ABS-KEY ( "modified rapid sequence induction" OR "modified rapid sequence intubation" OR "rapid sequence induction" OR "rapid sequence induction and intubation" OR "rapid sequence induction methods" OR "rapid sequence induction procedure" OR "rapid sequence induction protocol" OR "rapid sequence induction regimen" OR "rapid sequence induction rsi" OR "rapid sequence induction technique" OR "rapid sequence inductions" OR "rapid sequence intubation" OR "rapid sequence intubation agents" OR "rapid sequence intubation cases" OR "rapid sequence intubation induction" OR "rapid sequence intubation medications" OR "rapid sequence intubation method" OR "rapid sequence intubation protocol" OR "rapid sequence intubation protocols" OR "rapid sequence intubation rsi" OR "rapid sequence intubation rsi pre" OR "rapid sequence intubation short acting" OR "rapid sequence intubation technique" OR "rapid sequence intubations" ) ) AND ( PUBYEAR > 1999 AND PUBYEAR < 2025 ) AND ( LANGUAGE ( english ) )

Supplementary Figure 9

PRISMA flow chart for Research Question: In parturient undergoing Caesarean delivery under general anaesthesia with rapid sequence induction, is it safe to allow gentle face mask ventilation and release cricoid force if difficulty with ventilation or intubation encountered?

Supplementary Table 9b.

Summary table for included studies for Research Question: In parturient undergoing Caesarean delivery under general anaesthesia with rapid sequence induction, is it safe to allow gentle face mask ventilation and release cricoid force if difficulty with ventilation or intubation encountered?

RSI vs modified RSI in obstetric patients
Authors (Year)	Journal	Type of Article	Level of Evidence (AHA)	RSI Use Recommended	Cricoid Pressure Release Recommended	Gentle Face Mask Ventilation Recommended	Obstetric Population Included
Neilipovtz N (2007)[37]	Can J Anaesth	Meta-analysis	B-R*	Yes (if risk of aspiration is high)	Yes (if interfere with BMV or Intubation)	Yes (keep peak airway pressure below 15-20 cm H20)	No
Asai T (2015)[113]	J Anesth	Review	C-EO	Yes	Yes	May be	No
Banks A (2007)[117]	Anaesth Intensive Care Med	Review	C-EO	Yes	Not mentioned	Not mentioned	Yes
Choi SU (2022)[76]	Anesth Pain Med	Review	C-EO	Yes	Not mentioned	Not mentioned	No
Desai N (2018)[118]	Int J Obstet Anesth	Survey	C-LD	Yes	Not mentioned	Yes	Yes
Fleming N (2019)[119]	Anaesth Intensive Care Med	Review	C-EO	Yes	Yes	Not mentioned	No
Lee YL (2022)[82]	Singapore Med J	Retrospective analysis	B-NR	Yes	Yes	Yes ( released in 29 patients)	Yes (660 GA)
McDonnell NJ (2008)[48]	Int J Obstet Anesth	Prospective obs. study	B-NR	Yes	Not mentioned	Not mentioned	Yes
Meniolle F (2018)[120]	Prat Anesth Reanim	Review	C-EO	Yes	Yes	Yes	No
Mushambi MC (2016)[114]	Curr Opin Anaesthesiol	Review	C-EO	Yes	Yes	Yes	Yes
Patel S (2020)[32]	Curr Anesth Rep	Review	C-EO	Yes	Yes	Yes	No
Ramkumar V (2016)[7]	Indian J Anaesth	Guideline	B-R	Yes	Yes	Yes	Yes
Sharp LM (2009)[38]	Curr Opin Anaesthesiol	Review	C-EO	Not sure	Yes	Not mentioned	No

*Downgraded the evidence as it does not cover only obstetric patients. RSI=Rapid sequence induction; BMV=Bag mask ventilation; CP=Cricoid pressure; FMV=Face mask ventilation; GA=General anaesthesia; LOE=Level of Evidence

APPENDIX 10

Research Question 11: Does the availability of sugammadex support the use of rocuronium over succinylcholine in term parturients undergoing Caesarean delivery under general anaesthesia?

• Population: Parturients at term pregnancy undergoing Caesarean delivery under general anaesthesia

• Intervention- Rocuronium

• Control / Comparison- Succinylcholine

• Outcome- Episodes of desaturation

Supplementary Table 10a.

Concept table for Research Question: Does the availability of sugammadex support the use of rocuronium over succinylcholine in term parturients undergoing Caesarean delivery under general anaesthesia?

Research Question	Concept 1	Concept 2	Concept 3	Concept 4	Concept 5	Concept 6
Key concepts	Pregnancy	Term pregnancy	Cesarean	GA	Rocuronium	Succinylcholine
Free text terms/natural language terms (synonyms, UK/US terminology, medical/ laymen's terms, acronyms/ abbreviations, drug brands, more narrow search terms) Consider: phrase searching, proximity operators, truncation, wildcards, field qualification (e.g. textword)	pregnancies; pregnant; normal pregnancy; pregnancy normal; pregnan*	Parturient Parturitions last trimester. Pregnancy Trimester, Third Third Pregnancy Trimester Third Pregnancy Trimesters Pregnancy, Third Trimester Pregnancies, Third Trimester Third Trimester Pregnancies Third Trimester Pregnancy Trimester, Third Third Trimester Third Trimesters Trimesters, Third Last Trimester Last Trimesters Trimester, Last Trimesters, Last	Cesarean surgery; emergency Cesarean delivery; Elective cesarean delivery; Caesarean surgery; emergency Caesarean delivery; Elective caesarean delivery; obstetric surgeries; obstetric surgery Cesarean Section/ methods* Caesarean delivery Cesarean Sections Abdominal Delivery C-Sections (OB) Caesarean Section Caesarean Sections Delivery, Abdominal Abdominal Deliveries Deliveries, Abdominal Postcesarean Section Deliveries, Obstetric Obstetric Deliveries Obstetric Delivery	Anesthesia, General/methods* Anesthesia* Anesthesia, Obstetrical/ methods* Anesthesia, Obstetrical* Anesthesias, General General Anesthesia General Anesthesias	(“rocuronium”[MeSH] OR “rocuronium”[All Fields] OR “rocuronium s”[All Fields]) AND ((humans[Filter]) AND (english[Filter]))	(“succinylcholine”[MeSH] OR “succinylcholine”[All Fields]) AND ((humans[Filter]) AND (english[Filter]))
Controlled vocabulary terms/Subject terms (MeSH terms, Emtree terms) Consider: explode, major headings, subheadings	Pregnancy	“Term Birth”[Mesh] “Pregnancy Trimester, Third”[Mesh]	Cesarean Section “Cesarean Section”[Mesh] “Cesarean Section”[Mesh: NoExp] “Cesarean Section, Repeat”[Mesh: NoExp]	“Anesthetics, General”[Mesh] “Anesthesia”[Mesh] “Anesthesia, Obstetrical”[Mesh]

Search String:

PubMed: 25 results

(((("pregnancies"[Title/Abstract] OR "pregnant" [Title/Abstract] OR "normal pregnancy" [Title/Abstract] OR "pregnancy normal" [Title/Abstract] OR "pregnan*" [Title/Abstract] OR "pregnancy" [MeSH Terms]) AND ("humans"[MeSH Terms] AND "english"[Language])) OR (("Parturient"[Title/Abstract] OR "Parturitions"[Title/ Abstract] OR "Last Trimester"[Title/Abstract] OR "pregnancy trimester third"[Title/Abstract] OR "Third Pregnancy Trimester"[Title/Abstract] OR "Third Pregnancy Trimesters"[Title/Abstract] OR "pregnancy third trimester"[Title/ Abstract] OR "pregnancies third trimester"[Title/Abstract] OR "Third Trimester Pregnancies"[Title/Abstract] OR "Third Trimester Pregnancy" [Title/Abstract] OR "trimester third" [Title/Abstract] OR "Third Trimester" [Title/ Abstract] OR "Third Trimesters"[Title/Abstract] OR "trimesters third"[Title/Abstract] OR "Last Trimester"[Title/ Abstract] OR "Last Trimesters"[Title/Abstract] OR "trimester last"[Title/Abstract] OR "Term Birth"[MeSH Terms] OR "pregnancy trimester, third"[MeSH Terms]) AND ("humans"[MeSH Terms] AND "english"[Language])) OR (("Cesarean surgery"[Title/Abstract] OR "emergency Cesarean delivery"[Title/Abstract] OR "Elective cesarean delivery"[Title/Abstract] OR "Caesarean surgery"[Title/Abstract] OR "emergency Caesarean delivery"[Title/ Abstract] OR "Elective caesarean delivery"[Title/Abstract] OR "obstetric surgeries"[Title/Abstract] OR "obstetric surgery" [Title/Abstract] OR "cesarean section methods" [Title/Abstract] OR "Caesarean delivery" [Title/Abstract] OR "Cesarean Sections"[Title/Abstract] OR "Abdominal Delivery"[Title/Abstract] OR "c sections ob"[Title/Abstract] OR "Caesarean Section"[Title/Abstract] OR "Caesarean Sections"[Title/Abstract] OR "delivery abdominal"[Title/ Abstract] OR "Abdominal Deliveries"[Title/Abstract] OR "deliveries abdominal"[Title/Abstract] OR "Postcesarean Section" [Title/Abstract] OR "deliveries obstetric" [Title/Abstract] OR "Obstetric Deliveries" [Title/Abstract] OR "Obstetric Delivery"[Title/Abstract] OR "Cesarean Section"[MeSH Terms] OR "Cesarean Section"[MeSH Terms:noexp] OR "cesarean section, repeat"[MeSH Terms:noexp]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans"[MeSH Terms] AND "english"[Language]))) AND (("anesthesia general methods"[Title/Abstract] OR "anesthesia*"[Title/Abstract] OR "anesthesia obstetrical"[Title/Abstract] OR "General Anesthesia"[Title/Abstract] OR "General Anesthesias"[Title/ Abstract] OR "anesthetics, general"[MeSH Terms] OR "Anesthesia"[MeSH Terms] OR "anesthesia, obstetrical"[MeSH Terms]) AND ("humans"[MeSH Terms] AND "english"[Language] AND 2000/01/01:2024/12/31[Date - Publication]) AND ("humans"[MeSH Terms] AND "english"[Language])) AND (("modified rapid sequence induction"[All Fields] OR "modified rapid sequence intubation"[All Fields] OR "rapid sequence induction"[All Fields] OR "rapid sequence induction and"[All Fields] OR "rapid sequence induction and intubation"[All Fields] OR "rapid sequence induction and intubation adverse"[All Fields] OR "rapid sequence induction and intubation adverse effects"[All Fields] OR "rapid sequence induction and intubation instrumentation"[All Fields] OR "rapid sequence induction and intubation methods"[All Fields] OR "rapid sequence induction and intubation mortality"[All Fields] OR "rapid sequence induction and intubation rsii"[All Fields] OR "rapid sequence induction and intubation standards"[All Fields] OR "rapid sequence induction and intubation statistics"[All Fields] OR "rapid sequence induction and intubation statistics and"[All Fields] OR "rapid sequence induction and intubation statistics and numerical"[All Fields] OR "rapid sequence induction and intubation statistics and numerical data"[All Fields] OR "rapid sequence induction group"[All Fields] OR "rapid sequence induction intubation"[All Fields] OR "rapid sequence induction orotracheal"[All Fields] OR "rapid sequence induction orotracheal intubation"[All Fields] OR "rapid sequence induction procedure" [All Fields] OR "rapid sequence induction protocol" [All Fields] OR "rapid sequence induction regimen"[All Fields] OR "rapid sequence induction rsi"[All Fields] OR "rapid sequence induction technique"[All Fields] OR "rapid sequence induction techniques"[All Fields] OR "rapid sequence inductions"[All Fields] OR "rapid sequence intubation"[All Fields] OR "rapid sequence intubation agents"[All Fields] OR "rapid sequence intubation cases"[All Fields] OR "rapid sequence intubation induction"[All Fields] OR "rapid sequence intubation medications"[All Fields] OR "rapid sequence intubation method"[All Fields] OR "rapid sequence intubation protocol"[All Fields] OR "rapid sequence intubation protocols"[All Fields] OR "rapid sequence intubation rsi"[All Fields] OR "rapid sequence intubation rsi pre"[All Fields] OR "rapid sequence intubation short acting"[All Fields] OR "rapid sequence intubation technique"[All Fields] OR "rapid sequence intubations"[All Fields]) AND ("humans"[MeSH Terms] AND "english" [Language]) AND 2000/01/01:2024/12/31[Date - Publication] AND ("humans"[MeSH Terms] AND "english"[Language])) AND ((("rocuronium"[MeSH Terms] OR "rocuronium"[All Fields] OR "rocuronium s"[All Fields]) AND ("humans"[MeSH Terms] AND "english"[Language]) AND ("humans" [MeSH Terms] AND "english"[Language])) OR (("succinylcholine"[MeSH Terms] OR "succinylcholine"[All Fields]) AND ("humans"[MeSH Terms] AND "english"[Language]) AND ("humans"[MeSH Terms] AND "english"[Language])))) AND ((humans[Filter]) AND (english[Filter]))

Scopus : 64 results

( TITLE-ABS-KEY ( pregnancies OR pregnant OR "normal pregnancy" OR "pregnancy normal" OR pregnan* ) OR TITLE-ABS-KEY ( "Parturient" OR "Parturitions" OR "Last Trimester" OR "Third Pregnancy Trimester" OR "pregnancy third trimester" OR "Third Trimester Pregnancy" ) OR TITLE-ABS-KEY ( "Cesarean surgery" OR "emergency Cesarean delivery" OR "Elective cesarean delivery" OR "obstetric surgeries" OR "cesarean section methods" OR "Caesarean delivery" OR "Abdominal Delivery" OR "Postcesarean Section" OR "Obstetric Delivery" ) ) AND TITLE-ABS-KEY ( "anesthesia" OR "General Anesthesia" OR "anesthesia obstetrical" ) AND TITLE-ABS-KEY ( "rapid sequence induction" OR "rapid sequence intubation" OR "rapid sequence induction technique" ) AND TITLE-ABS-KEY ( rocuronium OR succinylcholine ) AND PUBYEAR > 1999 AND PUBYEAR < 2025 AND ( LANGUAGE ( english ) )AND PUBYEAR < 2025 AND (LANGUAGE(english))

Supplementary Figure 10

PRISMA flow chart for Research Question: Does the availability of sugammadex support the use of rocuronium over succinylcholine in term parturients undergoing Caesarean delivery under general anaesthesia?

Supplementary Table 10b.

Summary table for included studies for Research Question: Does the availability of sugammadex support the use of rocuronium over succinylcholine in term parturients undergoing Caesarean delivery under general anaesthesia?

Use of rocuronium in Caesarean delivery
Author (Year)	Journal	Type of article	Level of Evidence (AHA)	Intervention	Supports Rocuronium Use
Stourac P (2016)[121]	Anesth Analg	A Randomised Controlled, single blind, Noninferiority Trial	B-R	Caesarean section - Rocuronium (reversed with sugammadex) vs Suxamethonium	Non-inferior
Abu-Halaweh SA (2007)[122]	Saudi Med J	Randomised Control study	B-R	Elective/emergency CS. Rocuronium (1 mg/kg) vs Suxamethonium	Yes (no mention of sugammadex)
Kosinova M (2017)[36]	Int J Obstet Anesth	Randomised controlled trial	B-R	CS, Rocuronium vs Suxamethonium	Lower Apgar score at 1 minute with rocuronium. Normal at 5 and 10 min Apgar
Desai N (2018)[118]	Int J Obstet Anesth	Questionnaire survey (180 replies)	C-LD	CS, Rocuronium vs Suxamethonium	Roc used by 14% (vs 92% Sch) respondent but ready to adopt if sugammadex is available
Mushambi MC (2016) [114]	Curr Opin Anaesthesiol	Review article	C-LD	SCh is gold standard, but rocuronium in the dose of 0.9-1.2 mg kg can be used if sugammadex is available.	Yes
Ramkumar V (2016)[7]	Indian J Anaesth	Guidelines	C-EO	GA for CS - Suxamethonium or Rocuronium	Yes (only if Sch contraindicated as sugammadex was not available in country at the time of publication)
Lee YL (2022)[82]	Singapore Med J	4-year retrospective review	C-LD	GA for CS - Sch/Roc	No (cost-limited use)
Odor PM (2021)[123]	Anaesthesia	Prospective, multicentre observational study	B-NR	GA for obstetrics - Sch vs Roc (with sugammadex)	Yes (with availability of 41.1% patients reversed with sugammadex
Devroe S (2015)[50]	Curr Opin Anaesthesiol	Review article	C-LD	Rocuronium vs Suxamethonium	Yes (supports Roc at 1.0 mg/kg
Torres SM (2022)[124]	Braz J Anesthesiol	Case series	C-LD	Urgent non-obstetric surgery in pregnancy - Roc + sugammadex	Yes (but more evidence needed to establish safety of sugammadex)
Sharp LM (2009) [38]	Curr Opin Anaesthesiol	Review article	C-LD	CS - Rocuronium vs Suxamethonium	Yes
Nauheimer D (2012)[125]	Anaesthesist	Clinical series	C-EO	CS - Rocuronium reversed with sugammadex	Yes
Mushambi M (2015)[84]	Anaesthesia	Guidelines	C-EO	Roc (1-1.2mg/kg) vs Sch	Yes support Roc but with immediate availability of appropriate dose

CS=Caesarean section, SCh=Succinylcholine, Roc=Rocuronium, GA=General anaesthesia

ADDENDUM 1:

Supplementary Table Addendum 1.

Consensus and Stability Analysis of the Clinical Statements from the Delphi Survey

Obstetric Guidelines	Agree (%)	Neutral (%)	Disagree (%)	Median (IQR)	P
1. What is the maximum number of attempts at intubations that should be permitted to prevent airway management-related complications in a parturient?					1.0
• Maximum 1	0
• Maximum 2	17
• Maximum 2 + 1 (additional attempt should only be done by an experienced Anaesthesiologist)	83
• Maximum 4	0
2. What is the maximum number of attempts at supraglottic airway (SGA) insertion that should be permitted to prevent airway management-related complications in a parturient?					0.06
• Maximum 1	4
• Maximum 2	79
• Maximum 3	17
• Maximum 4	0
3. If application of cricoid force (Sellick's manoeuvre) is causing difficulty for face mask ventilation, cricoid force should be removed completely	100	0	0	7 (0)	0.06
4. If application of cricoid force (Sellick's manoeuvre) is causing difficulty in placement of a SGA, cricoid force should be removed completely.	96	4	0	7 (0)	0.97
5. If application of cricoid force (Sellick's manoeuvre) is causing difficulty for tracheal intubation (because of poor laryngeal view) cricoid force should be removed completely.	96	4	0	7 (0)	0.97
6. During rapid sequence Induction, in parturients undergoing caesarean delivery who are at a high risk of desaturation, gentle face mask ventilation (peak pressures limited to 20 cm H2O) should be used during the apnoeic period prior to intubation	100	0	0	7 (0)	0.60
7. Rocuronium should considered over succinylcholine for caesarean delivery under general anaesthesia at term, if adequate dose (16 mg/kg) of Sugammadex is available to reverse neuromuscular blockade immediately after an intubating dose of rocuronium is administered.	96	0	4	7 (0)	0.08
8. Following a failed intubation, when satisfactory ventilation is achieved through a properly placed 2nd generation SGA, general anaesthesia should be continued to complete the Caesarean delivery if the fetal and/or maternal status is compromised.	100	0	0	7 (0)	0.05
9. Tracheal intubation and ventilation using a 2nd generation SGA has failed, spontaneous breathing has NOT returned, however face mask ventilation is possible. In this setting, the obstetrician-anesthesiologist team should proceed to deliver the baby with continued application of cricoid force, if there is immediate threat to the life of the fetus or mother	100	0	0	7 (0)	0.61
10. Tracheal intubation and ventilation using a 2nd generation SGA has failed (face mask ventilation was possible). Adequate spontaneous breathing has returned and it is possible to maintain oxygenation and anaesthesia with the face mask. In this setting, the obstetrician-anaesthesiologist team should proceed to deliver the baby with continued application of cricoid force, if there is immediate threat to the life of the fetus or mother?	100	0	0	7 (0)	0.31
11. Tracheal intubation and ventilation using a 2nd generation SGA has failed, (facemask ventilation was possible). Spontaneous breathing has returned but is inadequate for maintaining effective oxygenation and anaesthesia with a face mask. In this setting, an additional dose of muscle relaxant should be administered to facilitate ventilation with continued application of cricoid force, allowing the obstetrician-anaesthesiologist team to proceed to deliver the baby, if there is immediate threat to the life of the fetus or mother.	96	0	4	7 (1)	0.05

IQR=Interquartile range

Funding Statement

All expenses related to the development of the guidelines were entirely funded by the All India Difficult Airway Association (AIDAA).