Comparison of Glottic Views and Intubation Times in the Supine and 25 Degree Back-up Positions

Study Overview
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Brief Summary
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Our hypothesis is that the view of the glottis may be improved by putting all patients requiring intubation in the ramped or back up position while maintaining the classic sniffing position.

Detailed Description
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The sniffing position has traditionally been considered the optimal head position for direct laryngoscopy and is the usual patient position preferred by most anaesthetists. In theory, neck flexion aligns the pharyngeal and laryngeal axes, and head extension at the atlanto-occipital joint aligns the oral axis with these two axes allowing the line of sight to fall on the glottis. It is recognized as the starting head position for direct laryngoscopy because it provides the best chance of adequate exposure. However the sniffing position does not guarantee adequate exposure in all patients because many other anatomical factors control the final degree of visualization. To achieve a proper sniffing position in obese patients, the ramped (or the back-up) position has been used as this produces better neck flexion and head extension in these patients when compared to the horizontal supine position. Also the forces required to elevate and move the tongue and other tissues out of the line of sight are less when the patients are ramped. Our hypothesis is that the view of the glottis may be improved by putting all (ie not only obese) patients requiring intubation in the ramped or back up position while maintaining the classic sniffing position.

Official Title
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Comparison of Glottic Views and Intubation Times in the Supine and 25 Degree Back-up Positions

Conditions
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Elective Surgical Patients

Intervention / Treatment
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* Procedure: 25 degree back-up position


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult surgical patients who required intubation as part of their routine anaesthesia Exclusion Criteria: Patients less than 18 years old, Patients recognised to have difficult airways where an alternative method of intubation (e.g. fibre optic) was the method of choice, Patients undergoing emergency surgery where patient positioning and data collection might cause delay (e.g. exsanguinating patients) or where the supine position is not optimal (e.g. brisk bleeding into the upper airway), Patients requiring rapid sequence induction of anaesthesia

Ages Eligible for Study
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Minimum Age: 18 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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Supine<br>A baseline group of adult patients who required intubation as part of their routine anaesthesia who were intubated in the standard horizontal sniffing position. | |
| Back-up<br>A subsequent group of similar the patients who had their anaesthesia induced and tracheas intubated in a 25 degree back-up position achieved by flexion of the operating table at the hips | Procedure: 25 degree back-up position<br>* To test whether a 25 degree back-up position improves laryngeal views and makes intubation easier compared to the standard horizontal position<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The Best Glottic View Obtained During Laryngoscopy | The best glottic view obtained during laryngoscopy was assessed using the Cormack and Lehane classification by the anaesthetist performing the laryngoscopy. The Cormack and Lehane classifies glottic views as follows: Grade 1: Most of the glottis is visible, Grade 2: At best almost half of the glottis is seen, at worst only the posterior tip of the arytenoids is seen., Grade 3: Only the epiglottis is visible, Grade 4: No laryngeal structures are visible. | The view of the glottis was measured once while the patient was being intubated | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The Number of Attempts at Both Laryngoscopy and Tracheal Intubation | The number of attempts at both laryngoscopy and tracheal intubation were recorded | Once at intubation | 
| The Use of Ancillary Equipment | The use of ancillary equipment (e.g. bougie, alternative laryngoscope blades) and manoeuvres (e.g. laryngeal manipulation) were recorded but applied at the intubating anaesthetist's discretion | Once at intubation | 
| The Time Between the Beginning of Laryngoscopy and Detection of Carbon Dioxide on the End-tidal Carbon Dioxide Monitor | The time between the beginning of laryngoscopy and detection of carbon dioxide on the end-tidal carbon dioxide monitor after the successful placement of the tracheal tube was recorded | Once at intubation | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Intubation, Back-up position; Glottis, View