Effect of Back up Head Elevated Position on Laryngeal Visualization.

Study Overview
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Brief Summary
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In patients with limited neck extension and mouth opening due to reasons including previous radiation therapy in the head and neck area or cervical spine pathology, tracheal intubation with direct laryngoscopy (DL) are challenging because of the difficulty in aligning the oral, pharyngeal, and laryngeal axes in order to visualize the cords. In contrast, video-laryngoscopes (VL) only require alignment of the pharyngeal and laryngeal axes, which lie along much more similar angles when compared with the oral axis. Thus, VL make tracheal intubation easier to accomplish in these patients. Good patient positioning also maximizes the chance of successful laryngoscopy and tracheal intubation. In difficult airway society 2015 guidelines, advantages of head-up positioning and ramping, which brings the patient's sternum onto the horizontal plane of the external auditory meatus (EAM), are highlighted. In the obese patient, the 'ramped' position should be used routinely because this improves the view during DL. This position is usually achieved by placing blankets or other devices under the patient's head and shoulders, but can also be achieved simply by configuring the operation room (OR) table into a back-up head elevated (BUHE) position. Significantly improved glottic views on DL have been reported with both obese and non-obese adult patients in BUHE position. However, the effect of this simple maneuver on laryngeal visualization with the VL in patients with limited neck extension and mouth opening has not been reported. The investigators hypothesized that BUHE position might improve laryngeal views and make intubation easier compared to the supine position with the VL in patients with simulated difficult airway (application of a cervical collar to limit mouth opening and neck movement).The investigator investigated primarily the improvement in visualization of the glottis and, secondarily, the ease of tracheal intubation after alignment of the EAM and sternal notch.

Official Title
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Effect of Back up Head Elevated Position on Laryngeal Visualization With the Video-laryngoscope in Patients With Simulated Difficult Airway.

Conditions
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Intubation;Difficult

Intervention / Treatment
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* Procedure: back up head elevated position


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: patients of ASA physical status 1-2 who were scheduled for elective surgery under general anaesthesia requiring tracheal intubation Exclusion Criteria: if they required rapid sequence induction; had a history of previous difficult direct laryngoscopy and required awake tracheal intubation; were unable or unwilling to provide informed consent; had uncontrolled hypertension; had a history of ischaemic heart disease without optimal control of symptoms; had a history of acute or recent stroke or myocardial infarction; had cervical spine instability or cervical myelopathy; had symptomatic asthma or reactive airway disease requiring daily pharmacological treatment for control of symptoms; or had a history of gastric reflux.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: neutral position<br>The initial percentage of glottic opening (POGO) by laryngoscopy was recorded in the ramped position. Thereafter, a second POGO (laryngeal view) was scored in the neutral position and then intubation was performed. | Procedure: back up head elevated position<br>* The patient was then placed in the back-up position to align the external auditory meatus and sternal notch, which was achieved by breaking the operating table at the hips to prevent patients from sliding off the table.<br>|
| Experimental: back up head elevated position<br>The initial POGO was recorded in the neutral position. The second POGO was scored in the ramped position and then the trachea was intubated. | Procedure: back up head elevated position<br>* The patient was then placed in the back-up position to align the external auditory meatus and sternal notch, which was achieved by breaking the operating table at the hips to prevent patients from sliding off the table.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| POGO score | percentage of glottic opening | During laryngeal visualization by laryngoscope over 1 minute period | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| intubation time | time required for intubation | The time from the insertion of laryngoscope into oral cavity until its removal over 1 minute period | 
| ease of tracheal intubation | number of optimization procedure to facilitate laryngeal visualization and tracheal intubation | The time from the insertion of laryngoscope into oral cavity until tracheal intubation over 1minute period |