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. 2023 Nov 17;120(46):779–785. doi: 10.3238/arztebl.m2023.0216

Anesthesia for Morbidly Obese Patients

Katharina Hardt 1,*, Frank Wappler 1
PMCID: PMC10762842  PMID: 37874129

Abstract

Background

The prevalence of morbid obesity (BMI >35 kg/m2) has risen steadily in recent decades. With the corresponding rise in the number of bariatric operations, anesthesiologists deal with this patient group more commonly than before, particularly in specialized centers.

Methods

This review is based on publications retrieved by a selective search in PubMed, including current guidelines and recommendations issued by specialist societies, as well as expert opinion.

Results

In the anesthesiological care of morbidly obese patients, a preoperative assessment and risk stratification are just as important as the thoughtful selection of the anesthesia technique, the drugs used and their dosage, and perioperative management. A thorough understanding of the pathophysiological changes and comorbidities of morbid obesity and the associated risks is essential. The risk of pulmonary complications such as respiratory failure, hypoxia, and apnea is markedly higher in morbidly obese patients, especially those with obstructive sleep apnea. Short-acting, less lipophilic anesthetic drugs are particularly useful, as is multimodal pain therapy for the avoidance of high opiate doses. The indication for intensified postoperative monitoring depends on the patient’s preexisting illnesses, the type of anesthesia, and the type of surgical procedure. Regional anesthetic techniques should be used if possible.

Conclusion

The perioperative care of morbidly obese patients presents special challenges. The anesthesiologist must be aware of potential comorbidities, specific risks, and pathophysiological changes in order to provide adequate care to this patient group.

cme plus

This article has been certified for by the North Rhine Academy for Continuing Medical Education. Participation in the CME certification program is possible only over the internet: cme.aerzteblatt.de. The deadline for submission is 16 November 2024.

The prevalence of morbid obesity (MO) in Germany has risen steadily in recent decades (e1). With the corresponding rise in the number of bariatric operations (1), anesthesiologists deal with this patient group more commonly than before, particularly in specialized centers. This review article is intended to provide an overview of the distinctive features of perioperative anesthesiological care of patients with MO and to present possible treatment strategies.

Methods

A selective search was conducted in PubMed and included current guidelines and recommendations issued by specialist societies, as well as expert opinion (review articles).

Definition, prevalence, and comorbidities of morbid obesity

MO is defined as a BMI greater than 35 kg/m2 (e2). According to a survey by the Robert Koch Institute, 46.6% of women and 60.5% of men in Germany are classified as overweight, with an obesity prevalence of 19.0% (e1).

MO harbors a high risk for various psychological and organic disorders (e3). However, an increased BMI does not in itself pose an increased perioperative risk. There is evidence that patients with an increased BMI may even have a lower mortality rate than patients of normal weight (e4). This phenomenon is referred to as the obesity paradox and is scientifically disputed, especially in view of the absence of any prospective randomized trials with comparison groups.

It should be pointed out that the different types of storage, distribution, and composition of body fat also play a decisive role. An increase in tissue types apart from adipose tissue, such as muscle mass, can also produce an increase in body weight that is pathological in purely mathematical terms. On the other hand, the percentage of fat mass can be underestimated in patients with little muscle mass, as is the case with elderly people (2).

Specific perioperative features

The body weight of MO patients confronts the care team with a number of challenges, for instance with regard to positioning and weight limits of equipment as well as from a medical and anesthesiological perspective.

Properative anesthesia screening

Preoperative assessment

The association of MO with certain anatomical features and comorbidities that affect outcome requires a thorough preoperative assessment of the patient. Patients with abdominal (visceral) fat distribution and metabolic syndrome have a high risk of comorbidities, such as diabetes mellitus, arterial hypertension, atrial fibrillation, and coronary heart disease, which in turn can cause perioperative complications (3). The severity level of these comorbidities needs to be noted. The anesthetist clinically evaluates the patient during the pre-operative assessment. It is essential to record their functional status and estimate their physical capacity (4). BMI is not suitable as a sole criterion for further investigations or special anesthetic techniques.

The difficult airway

Fat deposits around the face, pharynx, and in the tongue are commonly found in patients with MO. As a result, mask ventilation and endotracheal intubation can be more difficult than in patients of normal weight, albeit the data available on this issue is somewhat conflicting. A recent retrospective single-center trial involving 45 447 patients showed a greater probability of difficult mask ventilation in MO patients with an OR of 3.785 (95% confidence interval: [3.188; 4.493]; P <0.001) (5). A Danish registry-based study found a significant association of MO with difficult, or even failed, conventional intubation (OR: 1.34; [1.19; 1.51]; P <0.0001) (6). A prospective multi-center study involving around 500 000 evaluated cases reports the probability of difficult direct laryngoscopy combined with difficult mask ventilation in patients with a BMI ≥ 30 kg/m2 to be significantly increased (Table 1) (7). The European guidelines on preoperative risk evaluation mention a high BMI as a risk factor for difficult mask ventilation (>30 kg/m2) and intubation using direct laryngoscopy (>35 kg/m2) (8). An observation study, however, was not able to confirm this relationship. There was no relationship between the presence of a difficult airway and BMI when the involved 180 patients were placed in the “ramped position” (a semi-sitting position; upper body elevated by 30 to 45° with the head elevated) (9). The ramped position is recommended as the standard position for patients with MO (10) and can significantly improve conditions for intubation.

Table 1. Synoptic Table.

Authors Study design Relevant question Quantitative presentation Outcome
Preoperative assessment
Difficult airway
Kheterpal et al. (7) Prospective multicenter observation study; 500 000 pats. Correlation between BMI ≥ 30 kg/m2 and difficult mask ventilation combined with difficult direct laryngoscopy OR: 4,0; 95% CI: [3.3; 4.8], P >0.001(univariate analysis) Significantly increased risk of difficult mask ventilation combined with difficult direct laryngoscopy
Neligan et al. (9) Prospective single-center observation study; 180 pats. Correlation between difficult airway and MO (BMI: 49.4 kg/m2 [range: 36–77 kg/m2]) with pat. placed in ramped position* OR: 0.99; 95% CI: [0.92; 1.06], P = 0.8 No relationship between BMI and difficult airway when patient is placed in ramped position*
OSA
Ravesloot et al. (14) Prospective multidisciplinary single-center observation study; 279 pats. Prevalence of OSA among pats. undergoing bariatric surgery BMI: 30–34.9 kg/m2, n = 3: 33.3%;
BMI: 35–39.9 kg/m2, n = 75: 69.1%;
BMI: 40–49.9 kg/m2, n = 149: 69.1%;
BMI >50 kg/m2, n = 51: 80.4% 		Very high prevalence in pats. with morbid obesity, even with no previous diagnosis of OSA
Kaw et al. (20) Meta-analysis, 13 studies; 3942 pats. Association of OSA with perioperative complications Pats. with OSA: desaturation: OR: 2.27 (95% CI: 1.20; 4.26, P = 0.01), respiratory failure: OR: 2.43, (95% CI: [1.34; 4.39], P = 0.003), postoperative cardiac events: OR 2.07 (95% CI: [1.23; 3.50], P = 0.007) Significantly increased risk of perioperative respiratory and cardiac complications in pats. with OSA
Nagappa et al. (21) Meta-analysis, 11 studies; 1801 pats. Risk of perioperative adverse cardiac or cerebrovascular events in patients with OSA OSA versus non-OSA: 31% vs. 10.6%; OR: 2.4 (95% CI: [1.38; 4.2]; P = 0.002) Significantly increased risk for perioperative adverse cardiac events or cerebrovascular complications in pats. with OSA
Intraoperative management
Ventilation
Bluth et al. (31) Prospective randomized multicenter clinical trial in 23 countries; 2013 pats. BMI ≥ 35 kg/m2, VCV (TV: 7 mL kg IBW); PEEP: 12 cm H2O with alveolar recruitment maneuver vs. PEEP 4 cm H2O with respect to pulmonary complications within the first 5 postoperative days (ARDS, bronchospasm, pneumonia, pneumothorax, amongst others) and intraoperative (hypoxemia) Incidence of postoperative pulmonary complications: high level of PEEP: 211 of 989 pats. (21.3 %), low level of PEEP: 233 of 987 pats. (23.6%) (risk ratio: 0.93; 95% CI: [0.83; 1.04]; P = 0.23) No statistically significant advantage of high level of PEEP with alveolar recruitment maneuvers over low level of PEEP with respect to perioperative respiratory complications
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ARDS, acute respiratory distress syndrome; TV, tidal volume; BMI, Body Mass Index; IBW, ideal body weight; CI, confidence interval; OR, odds ratio; OSA, obstructive sleep apnea; PaCO2, arterial partial pressure of CO2; pats., patients; PEEP, positive endexpiratory pressure; postop., postoperative; SpO2, peripheral oxygen saturation; VCV, volume-controlled ventilation

*ramped position refers to a semi-sitting position with the upper body elevated by 30–45° and the head also raised

A number of clinical examinations can be used for the preoperative assessment of a potentially difficult airway. A large systematic Cochrane meta-analysis from 2018 showed that the screening tools had a low sensitivity with high variability (11), so only a combination of various tests and predictors appears to make sense (e5).

In any event, the airway management of obese patients should be well prepared and alternative strategies should be available.

Obstructive sleep apnea

Sleep-related breathing disorders play a significant role in patients with MO. Obstructive sleep apnea (OSA) is a risk factor for difficult intubation and is associated with an increased incidence of postoperative complications (12). OSA is characterized by repeated episodes of apnea during night sleep, which in turn can lead to hypoxia, repetitive arousal from sleep, increased respiratory work, sympathetic overactivity, and daytime somnolence (13). The prevalence of OSA is reported to be 60 to 90 percent in patients with MO undergoing bariatric surgery (14, 15). In contrast, its prevalence in patients with normal weight is between two and 26 percent (16, 17). The averaged prevalence of OSA requiring treatment in Germany is currently estimated to be 21% (18). A high number of unreported cases can be assumed for patients with MO. In an observation study, a total of 279 patients with MO (BMI: 44.2 ±6.4 kg/m2) underwent polysomnography prior to bariatric surgery. Although OSA had already been diagnosed in only 13.3%, it was subsequently identified in 69.9% of the patients. Indeed, 40.4% of the study participants even demonstrated severe OSA (14). Assertions and recommendations made for the perioperative management of OSA can therefore be applied to the majority of surgical patients with MO.

Standards for evaluating the risk of OSA should be available as an integral part of the preoperative preparation of obese patients (13). Although polysomnography is the diagnostic gold standard, it is not usually immediately and widely available. The STOP-BANG questionnaire (Table 2), on the other hand, is a simple and well validated tool for use during the preoperative risk assessment (19) and should be part of the “tools of the trade” of every anesthetist.

Table 2. STOP-BANG questionnaire for obstructive sleep apnea (modified acc. to [e6]).

Assessed feature Findings
Snoring Do you snore loudly (louder than talking or loud enough to be heard through closed doors)
Tiredness Do you often feel tired, fatigued, and sleepy during daytime?
Observed apnea Has anyone observed you stop breathing during your sleep?
Blood pressure Do you have, or are being treated for, high blood pressure?
BMI Body Mass Index ≥ 35 kg/m2
Age >50 years
Neck circumference >43 cm for men, >40 cm for women
Gender Male sex
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OSA – Low risk: Yes to 0–2 questions

OSA – Intermediate risk: Yes to 3–4 questions

OSA – High risk: Yes to 5–8 questions

or Yes to at least 2 of the first 4 questions + male sex

or Yes to at least 2 of the first 4 questions + BMI >35 kg/m2

or Yes to at least 2 of the first 4 questions + neck circumference (>43 cm for men, >40 cm for women)

A meta-analysis by Kaw et al. involving 3942 patients showed a significant increase in the risk for postoperative desaturation, acute respiratory failure, and cardiac events in those with OSA (20). A meta-analysis by Nagappa et al. involving 1801 patients also reports the risk of perioperative major adverse cardiac or cerebrovascular events in patients with OSA to be significantly increased (Table 1) (21).

In this context, mention should be made of the obesity hypoventilation syndrome, a ventilation disorder unrelated to night-time sleep, caused by fat-related collapse of the airways even in awake patients. Patients with MO associated with chronic combined hypoxic and hypercapnic (paCO2 ≥ 45 mmHg) respiratory failure are often referred under the misdiagnosis of COPD. In its severest form, this respiratory disorder is often associated with metabolic syndrome and almost always with OSA and is therefore highly relevant as regards the risk of perioperative cardiopulmonary complications (22).

Preoperative medications and instructions

The preoperative administration of benzodiazepines to adipose patients should be avoided due to the associated risk of apnea. Substances with fewer respiratory depression side effects, such as clonidine, may be considered to relieve anxiety. The usual restrictions apply regarding preoperative fasting (six hours for solid food, two hours for clear fluids).

General anesthetic induction and maintenance

Preoxygenation and general anesthetic induction

It is still disputed whether rapid sequence induction (RSI) with no manual ventilation should be performed in the presence of MO to reduce the potential risk for aspiration, even in the absence of clinically apparent heartburn. Although pressure in the abdominal cavity is indeed high from a purely functional aspect, the risk for aspiration in obese patients is not generally considered to be higher (23). However, in a large meta-analysis involving 460 984 patients, the prevalence of gastro-esophageal reflux was 1.7 times higher in those with a BMI equal to, or greater than, 30 kg/m2 (1.46; 2.06) than in normal weight patients (absolute prevalence: 14.2% versus 22.1%) (24). In actual practice, the main aim is to avoid hypoxia by shortening the period during which the patient can neither breath themselves nor can potentially be ventilated, so that a type of “modified RSI” is often undertaken anyway. Extensive pre-oxygenation using a tightly fitting mask (FiO2: 1.0, with a positive end-expiratory pressure (PEEP) of 5–10 cm H2O) is performed in the above-mentioned ramped position, followed by paralysis with high-dose rocuronium after induction of anesthesia. Succinylcholine is not recommended due to the increased oxygen demand during muscle depolarization. Then, unlike with “conventional” RSI, the shortest possible manual ventilation with a mask is performed until complete relaxation is obtained and intubation is possible. This can theoretically result in gastric inflation associated with an increased risk of aspiration, but in the authors’ opinion, however, this approach is justifiable when considering the risks and benefits. Evidence-based recommendations are lacking here. In some cases, primary use of a video laryngoscope is recommended for the intubation, among other things because, according to a recent meta-analysis, a higher success rate of the first intubation attempt can be expected here (25).

Breathing physiology and intraoperative ventilation strategies

Pulmonary comorbidities of MO include asthma, OSA, pulmonary arterial hypertension, and pulmonary restriction. Pathophysiologically, typical functional pulmonary changes develop as a result, such as less compliance and reduced residual capacity (26). As a result, life-threatening emergency situations can develop in a matter of seconds should ventilation and intubation problems arise.

There are no clear-cut recommendations available regarding the optimal ventilation strategy (volume versus pressure-controlled ventilation) for obese patients (27). Altered respiratory physiology often renders lung-protective ventilation difficult to deliver. Excessively high tidal volumes cause structural lung damage, known as volutrauma, which is similar to the damage found in acute respiratory distress syndrome (ARDS) (28). It is imperative that ventilation settings are oriented on the patient’s theoretical ideal body weight (IBW) (eTable) (“lungs do not grow with weight gain”). Box 1 contains recommendations for mechanical ventilation during surgery for obese patients (29).

eTable. Formulae for calculating fat-free body mass and ideal body weight.

Weight for calculation Reference Formula
Fat-free body mass, (LBW, lean body weight) LBW acc. to James (e7) Males: (1.1 × TBW) – (128 × [TBW/height (cm)]2)
Females: (1.07 × TBW) – (148 × [TBW/height (cm)]2)
LBW acc. to Janmahasatian (e8) Males:
9270 × TBW/(6680 + 216 × BMI)
Females:
9270 × TBW/(8780 + 244 × BMI)
Ideal body weight, (IBW) IBW acc. to Lemmens and Brodsky (e9) 22 × height (m2)
IBW acc. to Broca (e10) Males: height (cm) – 100
Females: height (cm) – 105
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TBW, total body weight; BMI, Body Mass Index

Box 1. Recommendations for the intraoperative ventilation of bariatric patients (29, 40).

  • Recruitment of lung tissue using PEEP (8–15 cm H2O) and intermittent recruitment maneuvers

  • Lung protective ventilation using low tidal volumes (approx. 6–8 mL/kg predicted body weight) to prevent volutrauma

  • Non-invasive ventilation in the early postoperative phase to avoid atelectasis and hypoxia

  • Appropriate adjustment of oxygen supply (FiO2 ideally <0.8) to avoid hypoxemia as well as resorptive atelectasis (“as low as possible, as high as necessary”)

  • Ventilation pressures should not exceed 30 cm H2O, if possible

  • Normocapnia should be achieved in the first instance by adjusting respiratory rate

  • Semi-sitting position

PEEP, positive end-expiratory pressure

Use of PEEP is essential for preventing atelectasis, although excessively high PEEP levels can result in barotrauma and hemodynamic instability. A recent meta-analysis concluded that volume-controlled ventilation with a high PEEP level (≥ 10 cm H2O) and intermittent recruitment maneuvers result in improved gas exchange and less pulmonary atelectasis formation (30). In contrast, a recent large prospective randomized study (PROBESE) shows no statistically significant advantage of high PEEP levels (12 cm H2O) together with recruitment maneuvers over low PEEP (4 cm H2O) with regard to perioperative respiratory complications (21.3 % versus 23.6%), even though intraoperative hypoxia occurred more frequently with low PEEP (49 [5.0%] versus 134 [13.6%] (high versus low PEEP) (risk ratio: 0.51 [0.40; 0.65]; P = 0.23) (31).

The patient should not be extubated until they are fully awake and alert, can follow commands precisely, and breath spontaneously and effectively. Residual muscle relaxation should be excluded beforehand using relaxometry and antagonized, if necessary, with appropriate drugs.

Drug dosing

Because prospective randomized studies are usually lacking, it is not yet possible to provide any evidence-based dosage or substance recommendations for anesthetics in patients with MO. General anesthetic maintenance based on actual total body weight (TBW) of obese patients runs the risk of overdosing. But also, underdosing drugs with the risk of intraoperative awareness must be avoided. This can occur as a result of the increased volume of distribution of the body. MO can alter drug clearance and tissue composition which can affect drug dosing. The lean body weight (LBW) is often mentioned as a basis for calculating drug dosages, e.g. in anesthesia induction (32). It can be calculated using bioelectrical impedance analysis or with often complex formulas (eTable). In everyday use, however, this is dispensed with in most cases due to the said complexity of the calculation and the inconclusive dosage recommendations. A recent practical review article by an advisory committee comprising anesthesiologists from five leading German centers for bariatric surgery recommends a standard dose calculation based on TBW, where the lower dosage limit should be used as a guide for weights above 150 kg (Table 3) (10). Careful titration of intravenous drugs to effect using intraoperative EEG/bispectral index (BIS) monitoring would appear appropriate for maintaining anesthesia and avoiding intraoperative awareness.

Table 3. Practice-orientated recommendations for drug dosing in obese patients (modified acc. to Nottelmann et al. [10]).

Medication (calculation and dose based on kg BW) Total body weight (TBW)
150 kg 200 kg 300 kg
Sufentanil
TBW × 0.2 µg/kg BW 		30 μg 40 μg 60 μg
Fentanyl
TBW × 2 µg/kg BW 		300 μg 400 μg 600 μg
Propofol
TBW × 1.5 mg/kg BW 		225 mg 300 mg 450 mg
Thiopental
TBW × 3 mg/kgKG 		450 mg 600 mg 900 mg
Rocuronium in mg/kg BW
TBW × 0.3 mg/kg BW 		45 mg 60 mg 90 mg
Rocuronium (RSI)
TBW × 0.6 mg/kg BW 		90 mg 120 mg 120 mg
Cisatracurium
TBW × 0.05 mg/kg BW 		7.5 mg 10 mg 15 mg
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BW, body weight; RSI, rapid sequence induction; TBW, total body weight

The pharmacokinetics of common anesthetic gases are only slightly altered (33), so that the risk of intraoperative awareness is reduced in contrast to total intravenous anesthesia (TIVA). Although desflurane is superior to sevoflurane in terms of controllability, with short wash-in and wash-out rates, it is currently becoming increasingly less relevant due to its considerable environmental impact and should only be used sparingly for minimal flow anesthesia.

In view of the high incidence of opiate-associated respiratory depression, current guidelines recommend as restrictive a use of opioids as possible in favor of a multimodal pain control, for example, in the form of a combination with lidocaine or ketamine or together with a regional anesthetic technique (34).

Prevention of postoperative vomiting and postoperative nausea

The risk factors for postoperative nausea and vomiting (PONV) include female sex, nonsmoker status, perioperative use of opiates, operating time of more than one hour, and the use of volatile anesthetics. Current data on MO as a risk factor for PONV is contradictory; so far it has been neither clearly identified as a protective nor as a risk factor. Multimodal PONV prophylaxis should involve a combination of two or more intravenous substances (for example, a long-acting corticosteroid, such as 8 mg dexamethasone, combined with a 5-hydroxytryptamine receptor antagonist [for example, 8 mg ondansetron], butyrophenone [for example, 1.25 mg dehydrobenzperidol], or 62.5 mg diphenhydramine) (10, 34).

Regional anesthesia

If possible, regional anesthesia techniques (epidural anesthesia, spinal anesthesia, peripheral nerve blocks) are preferable over general anesthesia in patients with MO (35). Controlled randomized studies dealing with this topic are lacking, however. In many cases, adequate regional anesthesia allows early mobilization and reduces systemic opiate use and its associated side effects. Furthermore, pulmonary problems and difficult intubation with potential complications are avoided. The visualization of anatomical structures may be limited in cases of MO by the inadequate penetration depth of ultrasound waves, requiring appropriate experience on the part of the sonographer.

If general anesthesia is absolutely necessary, this should ideally be supplemented by a regional technique. Use of local anesthetics for wound infiltration or at the trocar incision site can also be very useful for laparoscopic interventions. Such a combined approach is an elegant way of sparing intra- and post-operative anesthetics and opioids and reducing the risk of potential perioperative complications.

Postoperative management

The increased risk of respiratory complications in obese patients is a particular feature of the postoperative course of treatment. In an observation study involving 105 participants, the incidence of respiratory complications in patients with a BMI of between 35 and 55 kg/m2 was 8.57% and was even as high as 20% for a BMI of 55 kg/m2 (36). After bariatric surgery, all participants of a double-blind prospective single-center study demonstrated hypoxic phases with a peripheral oxygen saturation of below 90% for more than 30 seconds, some despite external oxygen administration. On average, 62 ± 16 (2; 184) of these hypoxic phases were observed per patient over 24 hours (37). Prolonged monitoring for at least 24 hours is therefore advised to avoid serious respiratory events.

Furthermore, even on completion of surgery, long-acting opioids and sedatives should only be administered with caution to patients with MO to avoid prolonged respiratory depression and airway collapse (35). Instead, regional techniques and non-pharmacological strategies (cooling, immobilization, etc.) should also be preferably adopted after surgery.

If OSA is known, continuous positive airway pressure (CPAP) therapy should be initiated immediately after extubation or be available in the recovery room at the latest. Non-invasive ventilation treatment combined with postoperative monitoring appears to be the most reliable approach to effectively reduce perioperative complications in patients with OSA (38).

Early postoperative mobilization of patients with MO is recommended, both to improve cardiopulmonary function and to lower the risk of thromboembolism (35), even if the risk of venous thromboembolism is low (0.42 %) (39).

The key aspects of the successful perioperative anesthesia care of patients with MO are summarized in Box 2.

Box 2. Key aspects of successful perioperative anesthesia care.

  • Take a thorough preoperative history and stratify risks

  • Prepare for possible ventilation and intubation problems, induce anesthesia and secure the airway in the “ramped position” as a modified form of rapid sequence induction (RSI)

  • Lung-protective ventilation

  • Intraoperative awareness monitoring, relaxometry, and calculated drug dosing

  • Note the relationship between morbid obesity and sleep-related breathing disorders (OSA, amongst others)

  • Avoid postoperative hypoxia and breathing arrests, consider implementing continuous positive airway pressure (CPAP) therapy

  • Multimodal pain management, use regional anesthesia procedures, and restrict use of opiates

  • A wide range of information and download material for patients and doctors as well as interesting new literature can be found on the website of the Society for Obesity and Bariatric Anaesthesia: www.sobauk.co.uk

Questions on the article in issue 46/2023:

Anesthesia in Morbidly Obese Patients

The submission deadline is 16 November 2024. Only one answer is possible per question.

Please select the answer that is most appropriate.

Question 1

Which definition of morbid obesity is quoted in the text?

  1. BMI >30 kg/m2

  2. Body fat percentage >20%

  3. Body fat percentage >30%

  4. BMI >35 kg/m2

  5. Obesity associated with type 2 diabetes

Question 2

Which position can improve intubating conditions in patients with morbid obesity and is therefore recommended?

  1. tummy position

  2. ramped position

  3. clamping position

  4. side position

  5. upright position

Question 3

In bariatric surgery, what percentage of patients with morbid obesity suffer from obstructive sleep apnea?

  1. 5–10%

  2. 10–20%

  3. 25–30%

  4. 35–50%

  5. 60–90%

Question 4

What is the gold standard test for diagnosing obstructive sleep apnea?

  1. Plethysmography

  2. Polysomnography

  3. Scintigraphy

  4. Lung function tests

  5. Air balloon test

Question 5

Which acronym is used in the questionnaire for examining obstructive sleep apnea?

  1. STOP-BANG

  2. SNORE-N8

  3. SNORE-STOP

  4. START-N8

  5. SNORE-MORE

Question 6

In the text, the use of which two substances is discouraged before and during anesthesia in patients with morbid obesity?

  1. Clonidine and rocuronium

  2. Benzodiazepines and succinylcholine

  3. Benzodiazepines and rocuronium

  4. Clonidine and succinylcholine

  5. Benzodiazepines and clonidine

Question 7

Which statement is mentioned in the text with respect to ventilation settings in patients with morbid obesity?

  1. “The lungs grow with weight gain.”

  2. “The lungs are stronger than you think.”

  3. “The lungs become softer with weight gain.”

  4. “The lungs do not grow with weight gain.”

  5. “The lungs are larger than you think.”

Question 8

Which statement applies to the use of regional anesthesia techniques in bariatric surgery?

  1. Spinal anesthesia should be avoided.

  2. Only peripheral nerve blocks should be used.

  3. The visualization of anatomical structures by ultrasound can be difficult in patients with morbid obesity.

  4. General anesthesia is preferred over a regional technique.

  5. Regional anesthesia means that post-operative mobilization is often only possible with some delay.

Question 9

Which of the following examples is not one of the risk factors named in the text for postoperative vomiting and nausea?

  1. female sex

  2. use of opiates

  3. smoker status

  4. operating time longer than one hour

  5. use of volatile anesthetics

Question 10

Which postoperative procedure is recommended to avoid respiratory complications in patients with morbid obesity who also suffer from obstructive sleep apnea ?

  1. Monitoring for at least 8 hrs. plus CPAP therapy

  2. Monitoring for at least 48 hrs. plus long-acting opioids

  3. CPAP plus long-acting opioids

  4. Monitoring for at least 24 hrs. plus CPAP therapy

  5. Invasive ventilation plus monitoring for at least 8 hrs.

Acknowledgments

Translated from the original German by Grahame Larkin, M.D.

Footnotes

Conflict of interest statement

The authors declare that no conflict of interest exists.

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