Neutral Position Facilitates Orotracheal Intubation With Videolaryngoscopes

Study Overview
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Brief Summary
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With the advent and more widespread use of video-assisted laryngoscopy (VL), the incidence of difficult intubation has decreased. However, the optimal position for endotracheal intubation facilitated by VL is not yet determined. The objective of this study is to evaluate the effects of different patient positioning (neutral position versus sniffing position) on the glottic view and intubation time during orotracheal intubation facilitated by two video-assisted laryngoscopes (McGrath laryngoscope and C-MAC D-blade laryngoscope). A total of 252 patients who required orotracheal intubation for elective surgery were included in the study. Primary outcomes include airway difficulty score(ADS), intubation difficulty scale (IDS), the percentage of glottic opening (POGO) and intubation time. By the indexes above and crossover analysis, the study aimed to prove the ideal position for VL.

Detailed Description
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Endotracheal tube general anesthesia (ETGA) is required for a variety of surgeries. Traditionally, the patient is placed in a sniffing position to facilitate endotracheal intubation with a direct laryngoscope. Increased attempts in intubation or intubation failed may be encountered during direct laryngoscope, leading to hypoxemia or neurological sequelae. Injure to the teeth, gingiva or lips is also sometimes unavoidable. With the advent and more widespread use of video-assisted laryngoscopy (VL), the incidence of difficult intubation has decreased. However, the optimal position for endotracheal intubation facilitated by VL is not yet determined. A previous study suggested that better glottic view is achieved when placing the patient in a neutral position than the sniffing position during orotracheal intubation by fiberoptic bronchoscopy. The objective of this study is to evaluate the effects of different patient positioning (neutral position versus sniffing position) on the glottic view and intubation time during orotracheal intubation facilitated by two video-assisted laryngoscopes (McGrath laryngoscope and C-MAC D-blade laryngoscope). A total of 252 American Society of Anesthesiologists I-II patients, in the age above 20 years, who required orotracheal intubation for elective surgery were included in the study. Patients received nasotracheal intubation, awake tracheal intubation, emergency surgery, required rapid-sequence intubation (RSI), those in pregnancy, with possible difficult intubation(with oropharyngeal pathology, limited neck mobility, previous head and neck surgical history), anticipated difficult intubation assessed by preoperative Airway Difficult Score(ADS)(≥ 7), with allergy history of common anesthetics agents or any underlying comorbidities which refrain them from receiving common anesthetic agents were excluded. The types of VL and the orders of position were randomly allocated by computer and the study take place in the operation room. Primary outcomes include airway difficulty (evaluated by ADS), ease of intubation (evaluated by intubation difficulty scale [IDS], the percentage of glottic opening [POGO]) and intubation time. By the indexes above and crossover analysis, the study aimed to prove the ideal position for VL, improve the efficiency of intubation and decrease the rate of difficult intubation by VL in the future.

Official Title
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Neutral Position Facilitates Orotracheal Intubation With Videolaryngoscopes: A Comparing Angulated (McGrath) and Hyperangulated (C-MAC With D-blade) Videolaryngoscopes

Conditions
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Orotracheal Intubation

Intervention / Treatment
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* Device: McGrath laryngoscope
* Device: C-MAC D-blade laryngoscope


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: age above 20 years Anesthesiologists I-II who required orotracheal intubation for elective surgery Exclusion Criteria: nasotracheal intubation awake tracheal intubation emergency surgery required rapid-sequence intubation (RSI) those in pregnancy with possible difficult intubation(with oropharyngeal pathology, limited neck mobility, previous head and neck surgical history) anticipated difficult intubation assessed by preoperative Airway Difficult Score (≥ 7) with allergy history of common anesthetics agents any underlying comorbidities which refrain them from receiving common anesthetic agents

Ages Eligible for Study
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Minimum Age: 20 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: from neutral to sniffing position<br>The patients in this group will be assessed firstly in the neutral position then subsequently in the sniffing position. | Device: McGrath laryngoscope<br>* The patients in this group will be evaluated and intubated with McGrath laryngoscope (angulated videolaryngoscope).<br>Device: C-MAC D-blade laryngoscope<br>* The patients in this group will be evaluated and intubated with C-MAC D-blade laryngoscope (hyperangulated videolaryngoscope).<br>|
| Active Comparator: from sniffing position to neutral position<br>The patients in this group will be assessed firstly in the sniffing position then subsequently in the neutral position. | Device: McGrath laryngoscope<br>* The patients in this group will be evaluated and intubated with McGrath laryngoscope (angulated videolaryngoscope).<br>Device: C-MAC D-blade laryngoscope<br>* The patients in this group will be evaluated and intubated with C-MAC D-blade laryngoscope (hyperangulated videolaryngoscope).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| airway difficult score (ADS) | Airway difficult score (ADS) represents the airway difficulty and it includes thyro-mental distance, Mallampati score, mouth opening, neck mobility and upper incisions. Each element will be scored from 1 to 3 points accordingly. The higher the scores are, the more difficult the airway could be. The minimum value and the maximum value of the airway difficult score (ADS) are 5 and 15 respectively. The definition of possible difficult airway is when the airway difficult score (ADS) score is more than 7 points. | Airway difficult score (ADS) is assessed before induction and it take about 3 minutes. | 
| intubation difficulty scale (IDS) | Intubation difficulty scale (IDS) represents ease of intubation and it includes times of intubation attempts, numbers of operators, grade of Modified Cormack-Lehane classification, lifting force, laryngeal pressure and vocal cord mobility. Intubation attempts, operators and grade of Modified Cormack-Lehane classification more than one will be scored directly to the numbers accordingly. The other elements will be scored from 0 to 1 point. The higher the scores are, the more difficult the intubation could be. The minimum value of the IDS is 0 and there is no limit of the maximum value. The definition of difficult intubation is when the intubation difficulty scale (IDS) score is more than 6 points. | intubation difficulty scale (IDS) is assessed during intubation and the time it take depend on the difficulty of the case. | 
| percentage of glottic opening (POGO) | Both the glottic views in first position and in second position are evaluated as percentage of glottic opening (POGO) score, ranging from 0 to 100%. The glottic views will be recorded as digital image and be evaluated by another anesthesiologist subsequently. | Percentage of glottic opening (POGO) is evaluated by another anesthesiologist up to 24 hours after intubation ,and it take about 1 minutes. | 
| intubation time | Time from when the patient's mouth is opened to the time when intubation is completed and the EtCO2 is detected by the monitor will be recorded. | Intubation time is assessed during intubation and the time it take depend on the difficulty of the case. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| complications | Complications include tissue injury (injury to the teeth, gingiva or lips), sore throat, hoarseness and desaturation (SpO2<95%), which are recorded as happened or not happened. | Tissue injury, sore throat and hoarseness are evaluated in the postoperative period (the day after the surgery). Desaturation or not is assessed during the procedure. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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orotracheal intubation, neutral position, sniffing position, video-assisted laryngoscopes