Awake suction tracheal extubation using a tracheal tube as a suction catheter: study protocol for a randomised controlled non-inferiority trial

Abstract

Introduction

During recovery from general anaesthesia with tracheal intubation, the tracheal extubation is a necessary step. 22% of anaesthesia-related complications occur after extubation. In a few patients, the hypoxic brain injury and death may occur. Inflation and suction techniques are two common techniques for tracheal extubation; however, it is unclear which technique is superior. In our practice, the suction tracheal extubation is typically performed via a suction catheter, and the tracheal and oropharyngeal secretions are often not completely cleared. Additionally, cough often occurs. When a suction catheter is substituted with a tracheal tube, the clearance of tracheal and oropharyngeal secretions seems to improve. In addition, even without prior tracheal and oropharyngeal suctions before tracheal extubation, the tracheal and oropharyngeal secretions can be effectively cleared when a tracheal tube is used as a suction catheter. This study was designed to investigate the use of tracheal tubes as suction catheters in awake suction tracheal extubation.

Methods and analysis

This single-centre, single-blinded, prospective, non-inferiority, randomised controlled trial will include 600 patients (aged 18–65 years, American Society of Anesthesiologists score <grade III) who will undergo elective surgery. All participants will receive general anaesthesia and be randomly divided into four groups: Inflation, Suction_{suction catheter}, Suction_{tracheal tube-1} and Suction_{tracheal tube-2} groups. In the Inflation group, a positive airway pressure will be given via the anaesthesia machine during awake tracheal extubation. In the Suction_{suction catheter} group, negative pressure suction will be implemented during awake tracheal extubation by inserting a suction catheter into the trachea. In the Suction_{tracheal tube-1} and Suction_{tracheal tube-2} groups, negative pressure suction will be applied during awake tracheal extubation by directly connecting the tracheal tube with a negative pressure suction device. In the Inflation, Suction_{suction catheter} and Suction_{tracheal tube-1} groups, the tracheal and oropharyngeal suctions under anaesthesia state will be carried out before cuff deflation and removal of the tracheal tube. In the Suction_{tracheal tube-2} group, the tracheal and oropharyngeal suctions will not be performed. The primary outcome is the incidence of blood oxygen saturation <92% within 10 min after tracheal extubation. The secondary outcomes include the dose of general anaesthetics, the duration of surgery and anaesthesia, the duration in the postanaesthesia recovery room (PACU), the length of hospital stay, the airway complications before leaving the PACU, the respiratory intervention before leaving the PACU and the postoperative complications within 3 days.

Ethics and dissemination

This study was approved by the Ethics Committee of Shenzhen Traditional Chinese Medicine Hospital, The Fourth Clinical Medical College of Guangzho University of Chinese Medicine (Permit No. K2022-162-01, Chairperson Professor Mingzhen Xu) on 17 October 2022 and was registered at the Chinese Clinical Trial Registry (https://www.chictr.org.cn/usercenter.aspx) on 18 November 2022 (identifier ChiCTR2200065904). The study results will be disseminated through peer-reviewed journals, professional societies and meetings.

Trial registration number

ChiCTR2200065904.

STRENGTHS AND LIMITATIONS OF THIS STUDY.

• We will implement specific measures (eg, exclusion criteria and tracheal extubation criteria) to minimise the potential factors that may influence the conclusion.

• We will recruit an additional 11.1% of patients to compensate for dropouts and protocol violations.

• This study does not include all types of surgical patients.

• This study is a single-blinded study.

Introduction

Tracheal extubation is a necessary step during recovery from general anaesthesia with tracheal intubation. It has been reported that 22% of anaesthesia complications occur after tracheal extubation.¹ Although most of these complications do not cause severe injury in patients, some serious consequences (eg, hypoxic brain injury and death) still occur in a subset of patients.^{2 3} Therefore, proper tracheal extubation is important for reducing complications, relieving discomfort and improving prognosis.

There are two common techniques for tracheal extubation, inflation and suction techniques.^{4 5} For the inflation technique, the lung is inflated via a positive airway pressure before cuff deflation and removal of the tracheal tube.⁶ The inflation technique decreases the incidence of atelectasis and facilitates the evacuation of tracheal secretions.⁷,¹⁰ However, the inflation technique can cause cough and discomfort.⁷,¹⁰ In addition, the secretions, which are evacuated from the trachea to the mouth, may be repeatedly aspirated into the trachea. The inflation technique is recommended for low-risk patients by the Difficult Airway Society Guidelines.⁶

For the suction technique, a suction catheter is inserted into the trachea and the cuff is deflated; next, the tracheal tube is subsequently removed while a negative pressure is applied via the suction catheter.⁴ Suction technique is widely used in China and is associated with an increased incidence of atelectasis and hypoxaemia.⁴ In the children, it has been proven that the inflation technique is superior to the suction technique in terms of the frequency of arterial haemoglobin oxygen desaturation and the onset of desaturation.⁵ In the adults, no difference has been observed in the onset of desaturation between the two techniques.⁴ Therefore, it is not thoroughly clear which method is superior.

In our practice, when suction tracheal extubation via a suction catheter is used, the tracheal and oropharyngeal secretions are not completely cleared. Coughing often further clears the residual tracheal and oropharyngeal secretions. When we occasionally perform suction tracheal extubation by using a tracheal tube as a suction catheter, tracheal and oropharyngeal secretion clearance seems to improve. Although the connection between the tracheal tube and the suction machine is looser than that of the suction catheter, the tracheal tube has a larger lumen diameter than the suction catheter. With respect to both the inflation and suction technique, tracheal and oropharyngeal suctions are first performed before tracheal extubation.⁴ When a tracheal tube is used as a suction catheter, during the extubation of the tracheal tube from the trachea and oropharynx, the tracheal and oropharyngeal secretions can also be effectively cleared, even without prior tracheal and oropharyngeal suctions. In addition, among adults in France, the effect of the suction technique is similar to that of the inflation technique.⁴ Therefore, we hypothesise that for tracheal extubation in China, the inflation and suction techniques will have similar effects; however, when performing suction tracheal extubation, directly using a tracheal tube is superior to using a suction catheter. Furthermore, the tracheal and oropharyngeal suction before tracheal extubation may be unnecessary when a tracheal tube is used as a suction catheter. This randomised controlled trial (RCT) is designed to investigate the effect of suction tracheal extubation via using a tracheal tube as a suction catheter.

Methods and analysis

Study design

This single-centre, single-blinded, prospective, non-inferiority, RCT was reported in compliance with the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) guidelines (for details, see online supplemental additional file 1). This study will be conducted in accordance with the ICH-good clinical practice (GCP) and the Helsinki Declaration at the Department of Anesthesiology of Shenzhen Traditional Chinese Medicine Hospital, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine. The schedule of enrolment, interventions and assessments is shown in figure 1. The trial flow chart is shown in figure 2.

Figure 1. Schedule of enrolment, interventions and assessments. OR, operating room; PACU, postanaesthesia recovery room; SpO2, blood oxygen saturation.

Figure 2. Study flowchart. ASA, American Society of Anesthesiologists; BMI, body mass index; PACU, postanaesthesia recovery room; SpO2, blood oxygen saturation.

Ethical approval

This study was approved by the Ethics Committee of Shenzhen Traditional Chinese Medicine Hospital, The Fourth Clinical Medical College of Guangzhou University of Chinese Medicine (Permit No. K2022-162-01, Chairperson Professor Mingzhen Xu, Email address: szszyyll@126.com) on 17 October 2022 and was registered at the Chinese Clinical Trial Registry (https://www.chictr.org.cn/index.html) on 18 November 2022 (identifier ChiCTR2200065904).

Participants

Patients (aged 18–65 years, American Society of Anesthesiologists (ASA) score <grade III), who are scheduled for elective surgery, will be recruited as participants in this study. All participants will fast for 2–3 hours for clear liquids and 6–8 hours for non-fatty solids. This study will not result in any additional costs. The surgeries will be performed under general anaesthesia with tracheal intubation. The model consent form has been submitted as the second online supplemental file 1. Participants with an inability to communicate, acute respiratory infection, obstructive sleep apnoea, a body mass index >30 kg/m², a Modified Mallampati score ≥grade III, chronic respiratory insufficiency, chronic cardiac insufficiency or the use of a non-standard endotracheal tube or surgical site involving the heart, lung, brain, ear, nose, throat or maxillofacial region will be excluded from the study.

Randomisation and blinding

Written informed consent will be first obtained from all participants before randomisation. For blocked randomisation, all participants will be assigned a serial number (1∼600) according to the time and date of surgery and be divided into 65 blocks. 16 participants with adjacent times and dates of surgery will be placed into a block. For each block, from a random number table, 16 participants will be allocated a group of random number, which is different for any two blocks. Afterwards, the random numbers of each block will be sorted from small to large and assigned serial numbers from 1∼16 to label the participants. Participants with numbers 1, 5, 9 and 13 will be assigned to the Inflation group. Participants with numbers 2, 6, 10 and 14 will be assigned to the Suction_{suction catheter} group. Participants with numbers 3, 7, 11 and 15 will be assigned to the Suction_{tracheal tube-1} group. Participants with numbers 4, 8, 12 and 16 will be assigned to the Suction_{tracheal tube-2} group. The random serial numbers of each subject will be placed in a sealed envelope. Before this study is conducted, randomisation will be performed by a research assistant, who will allocate a random serial number to a newly recruited subject and tell the anaesthesiologists. Because the anaesthesiologists will perform tracheal extubation, they cannot be blinded to the group allocation. However, the participants, surgical team and outcome assessor (another research assistant) will be blinded to the information concerning randomisation and group allocation. Outcome assessments and statistical analyses will be performed by the outcome assessor.

Intervention

Once the patient enters the operation room, the patient’s ECG, heart rate, blood oxygen saturation (SpO2) and non-invasive blood pressure will be monitored. Venous access will be established, followed by infusion of Ringer’s lactate. General anaesthesia with tracheal intubation will then be administered to all patients. Midazolam (0.02 mg/kg), remifentanil target controlled infusion (4–8 ng/mL), propofol target-controlled infusion (2–4 µg/mL) and cisatracurium (0.15 mg/kg) will be used for anaesthesia induction. After tracheal intubation (standard endotracheal tube, 7.0 # for females, 7.5 # for males), mechanical ventilation will be performed (oxygen concentration=40%¹¹,¹³). Remifentanil target-controlled infusion (4–8 ng/mL), propofol target-controlled infusion (2–4 µg/mL) and cisatracurium (0.09 mg/kg/hour) will be used to maintain anaesthesia. End-expiratory carbon dioxide, Bispectral Index (BIS), blood pressure, heart rate and body temperature will be maintained at 35–45 mm Hg, 40–60, ±20% of the baseline value, 60–100 beats/min and ≥36℃, respectively. After anaesthesia induction, dexamethasone (4 mg) will be used. Before surgery, pentazocine (30 mg) and flurbiprofen (50 mg) will be injected. Before the end of surgery, azasetron (10 mg) will be given.

After the operation, the administration of general anaesthetics will cease and the patient will be transferred to the postanaesthesia recovery room (PACU). In the PACU, once three responses to train-of-four stimulation are observed, neostigmine (0.04 mg/kg) and atropine (0.02 mg/kg) will be administered to reverse the effects of cisatracurium. In this study, tracheal extubation will be performed for all the patients in an awake state. Before tracheal extubation, the patients must meet the following criteria⁴: (1) SpO2 >90%; (2) regular spontaneous breath recovery and adequate minute ventilation is adequate; (3) ability to respond to a verbal command and/or spontaneously open their eyes; (4) stable haemodynamic parameters and body temperature is approximately the baseline value; and (5) train-of-four ratio ≥0.9.¹⁴,¹⁶ Based on the tracheal extubation technique, the patients will be divided into four groups: Inflation, Suction_{suction catheter}, Suction_{tracheal tube-1} and Suction_{tracheal tube-2} groups.

In the Inflation group, once the patient is awake, a positive airway pressure (40 cm H₂O, 15 s¹⁷) will be applied; then the cuff will be deflated and the tracheal tube will be removed.⁴ In the Suction_{suction catheter} group, once the patient is awake, a suction catheter connected with a negative-pressure suction device will be inserted into the trachea via a tracheal tube. Afterwards, the cuff will be deflated, and the tracheal tube together with the suction catheter will be removed.⁴ In the Suction_{tracheal tube-1} and Suction_{tracheal tube-2} groups, the tracheal tube will be used as a suction catheter (figure 3). Once the patient is awake, the cuff will be deflated, and the tracheal tube directly connected to a negative-pressure suction device will be removed (figure 3). Before the cuff deflation and removal of the tracheal tube, the tracheal and oropharyngeal suctions under anaesthesia state⁴ will be carried out in the Inflation, Suction_{suction catheter} and Suction_{tracheal tube-1} groups but will not be executed in the Suction_{tracheal tube-2} group. After tracheal extubation in all four groups, patients will breathe room air; once there are secretions in the oropharynx, oropharyngeal suction will be carried out again. If the patient feels pain, pentazocine will be administered. Once the SpO2 is lower than 92%, supplemental oxygen, mask ventilation or reintubation will be provided.⁴

Figure 3. Suction tracheal extubation via using a tracheal tube as a suction catheter. (a) Awake patient without tracheal extubation. (b) 5 mL syringe and cuff. (c) Insertion of a 5 mL syringe in the cuff and cuff deflation. (d) Suction machine. (e) Connectors of the tracheal tube and suction machine. (f) Connection between tracheal tube and suction machine. (g) Partial withdrawal of the tracheal tube. (h) Entire withdrawal of the tracheal tube. (i) Awake patient with tracheal extubation.

Data acquisition

Before anaesthesia, the name, ID number, sex, age, height, weight, tobacco use, preoperative diagnosis, surgical procedures, ASA score and Modified Mallampati score^{18 19} will be documented. Within 10 min after tracheal extubation, the incidence of SpO2 <92% will be recorded.⁴ Before patients leave the PACU, the data concerning anaesthesia (total dose of propofol, remifentanil, pentazocine and cisatracurium) will be recorded. In addition, the duration of surgery and anaesthesia, the duration in the PACU will also be recorded.

Before patients leave the PACU, airway complications (cough, airway obstruction, laryngospasm, bronchospasm and aspiration of gastric content) will be documented, along with any respiratory interventions (supplemental oxygen, mask ventilation and reintubation) that will be noted. Within 3 days after the patient returns to the ward, the postoperative complications (unexpected supplemental oxygen, pneumonia and atelectasis) will be recorded. After discharge from the hospital, the length of hospital stay will be documented.

Study outcomes

Primary outcome

Incidence of SpO2 <92% within 10 min of tracheal extubation.

Secondary outcomes

1. Doses of general anaesthetics (propofol, remifentanil, pentazocine and cisatracurium).

2. Time of operation and anaesthesia; time in the PACU; hospital stay.

3. Airway complications (cough, airway obstruction, laryngospasm, bronchospasm and aspiration of extratracheal content) before the patient leaves the PACU.

4. Respiratory intervention (supplemental oxygen, mask ventilation and reintubation) before leaving the PACU.

5. Postoperative complications (unexpected supplemental oxygen, pneumonia and atelectasis) occurring within 3 days.

SpO2 is the most important monitoring index. In some patients, SpO2 <92% does not occur. Therefore, the incidence of SpO2 <92% will be selected as the primary outcome, not the time between tracheal extubation and a decrease in SpO2 <92%.^{4 5} The incidence of SpO2 <92% will be the confirmatory outcome, and the other measured variables will be considered exploratory outcomes.

Adverse events

Before the beginning of the study, all research team members will undergo rigorous training to accurately monitor participants and promptly identify adverse events. In accordance with the SPIRIT recommendations, all adverse events, especially those resulting in death, life-threatening conditions or hospitalisations, will be noted. All adverse events will be actively managed until resolution, stabilisation or confirmation they are unrelated to the study treatment. All participants do not have to pay for the treatment of adverse events. In the event of an adverse event, the participant will be unblinded, and the study team and relevant specialists will collaboratively determine the seriousness and causality of these events. The chief investigator will report all adverse events to the ethics committee within the stipulated timeframe.

Withdrawal and dropout

The recruited participants may withdraw from this study at any time if they violate the study protocol or do not wish to continue. All adverse event and study outcome data will be regularly audited by the Data Safety and Monitoring Committee (DSMC). This study will be stopped if serious adverse events occur or once the number of recruited patients reaches the predetermined sample size.

Confidentiality

At recruitment, the research assistant will allocate a unique scrambled study number to each participant as the sole identification of the participants. All printouts of digital files and data collection sheets will be locked in a filing cabinet in a safe office with limited access. The deidentified participant records will be stored separately from the master list of participants and informed consent forms. The digital files will be saved with passwords on a firewall protected computer. Only the study sponsor has the privilege to access the final study data set. Signed consent must be obtained from each participant in the ancillary study, if the data collection or requests are not covered by the original informed consent process for the main clinical trial.

Study oversight

A study management group, which includes the chief investigator, study manager, study coordinator, data manager and study statistician, will keep in contact with each other every week. To guarantee that the study is carried out according to relevant regulations, study protocols and the principles of GCP, the DSMC will routinely supervise the study progress. In addition, to review safety data, the DSMC will convene two times a month via the internet, or more frequently if necessary. The DSMC must include three independent members (a study statistician and two clinical specialists) who are not involved in the research.

Protocol amendments

Protocol amendments must be approved by the sponsor, funding body and DSMC before application for ethical approval. Once ethical approval is obtained, the relevant parties (eg, study investigators, study registration authority or study participants) will be informed and amend the protocol accordingly.

Patient and public involvement

The development of the current research question and outcome measures was informed by patients’ priorities, experience and preferences such that this type of suction tracheal extubation via using a tracheal tube may be more suitable for patients who underwent general anaesthesia with tracheal intubation. The patients did not participate in the study design. Patients can express their concerns and questions when they are recruited and when the study is implemented. The patients will receive the study results via email. The patients will not participate in the outcome assessments. All measured outcomes will be evaluated by a research assistant.

Dissemination policy

The study results will be published in a professional journal and be disseminated to patients, clinical audiences, professionals, policymakers, health commissioners and the general public. The criterion for researchers to be listed as authors is that the researchers must have engaged in the study for more than 6 months.

Statistical analysis

Sample size calculation

In previous studies, the time between tracheal extubation and a decrease in SpO2 to 92% was used as the primary outcome. Because the SpO2 <92% does not occur in some patients, the incidence of SpO2 <92% within 10 min after tracheal extubation was used as the primary outcome for calculating the sample size. In L’Hermite et al’s study, when the routine suction technique was used, the incidence of SpO2 <92% within 10 min after tracheal extubation was 42.8%.⁴ If the difference in the incidence of SpO2 <92% was greater than 15%, it would be considered to be significant. Using this equation ($n=\frac{2\times p\times \left(1-p\right)\times {\left(z_{\left(1-\alpha \right)}+z_{\left(1-\beta \right)}\right)}^2}{{\mathrm{△}}^2}$),²⁰ the sample size will be calculated (one-sided). Assuming a power of 0.80 and a type I error protection of 0.05, 135 subjects are required in each group. To compensate for dropouts and protocol violations, we plan to recruit at least 600 subjects in this study.

Outcome analysis

SPSS V.13.0 software will be used for statistical analysis. Continuous data will be presented as the mean (SD). Χ² tests will be used to compare the primary outcome measures (ie, incidence of SpO2 <92%). For secondary outcomes, the continuous data (dose of general anaesthetics; time of operation and anaesthesia; time in the PACU; hospital stay) will be analysed with one-way analysis of variance (normally distributed data) or K independent samples tests (non-normally distributed data). Other enumeration data (airway complications; respiratory intervention; postoperative complication) will be analysed with χ² tests. A p value less than 0.05 will be considered to indicate statistical significance.

Discussion

The choice between the inflation or suction technique for tracheal extubation remains controversial.^{4 5} Among adults in France, both techniques have been reported to have similar effects.⁴ After general anaesthesia, the secretions typically accumulate around the tracheal tube above the cuff and below the vocal cords.⁷ When a tracheal tube is used as a suction catheter, these accumulated secretions can theoretically be removed. Furthermore, the larger lumen diameter of the tracheal tube may enhance suction efficiency. Therefore, we designed this single-centre, single-blinded, prospective, non-inferiority, RCT to further verify our hypotheses that for tracheal extubation, the suction and inflation techniques have similar effects in China; for suction tracheal extubation, using a tracheal tube directly as a suction catheter is more effective than using a suction catheter; and tracheal and oropharyngeal suctions are unnecessary before cuff deflation and tracheal extubation. Our preliminary results from a small sample of participants have verified the above hypotheses. The study results will help to simplify the extubation technique, reduce medical costs, decrease complications, relieve discomfort and improve prognosis.

Strength

There are several strengths in this study. First, tracheal extubation is a critical procedure during recovery from general anaesthesia,²¹ and improper management may result in some serious complications.^{2 3} Inflation and suction techniques are the two most common techniques for tracheal extubation,⁴ but few studies have compared their effects;^{4 5} thus, it remains unclear which technique is superior, especially among Chinese individuals. In this study, we will investigate the effects of the two techniques in greater depth. Our preliminary data revealed that the suction technique for tracheal extubation was not inferior to the inflation technique, although the inflation technique is theoretically superior.²²,²⁵ Second, under general anaesthesia, secretions typically accumulate around the tracheal tube and are above the cuff and below the vocal cords.⁷ Therefore, it is reasonable to use the tracheal tube directly as a suction catheter. This study is the first to investigate the effect of the suction technique for tracheal extubation by using a tracheal tube as a suction catheter. In this suction technique, an extra suction catheter is unnecessary. Third, the lumen diameter of the tracheal tube is larger than that of the suction catheter, theoretically improving suction efficiency, as supported by our preliminary data. Thus, tracheal and oropharyngeal suction are not performed before tracheal extubation under general anaesthesia. This is the first study to investigate the effect of suctioning directly via a tracheal tube without tracheal and oropharyngeal suctions, which may further simplify the tracheal extubation procedure and decrease the irritation to patient and decrease patient irritation.²⁶,²⁸

Limitations

This study has several limitations. First, in this study, in order to minimise the study risks, we have excluded some special patients, in whom there are some factors that may increase the incidence of SpO2 <92%. The conclusion of this study will not be suitable for all surgical patients underwent general anaesthesia with tracheal intubation. Second, the tracheal extubation must be carried out by the anaesthesiologists, who inevitably know the group allocation. This study cannot be a double-blinded study. This single-blinded study may decrease the credibility of the study conclusion. Third, the techniques of tracheal extubation under awake state will be investigated. The other techniques (eg, tracheal extubation under deep anaesthesia state) will not be used in this study. Under awake state, the tracheal tube may induce bucking in some patients,²⁶,²⁸ and they may feel discomfort caused by bucking.