Comparing Full vs. Partial Glottis View Using CMAC D-Blade Video Laryngoscope in Simulated Cervical Injury Patient

Study Overview
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Brief Summary
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Direct laryngoscope requires proper alignment of the oro-pharyngeal-laryngeal axis to provide an optimal glottic view for intubation. However, in cervical spine patients, this alignment is not possible thus resulting in an increased risk of fail intubations. D-blade comes with an elliptically tapered blade shape rising at the distal end to provide better glottic visualization in comparison with direct laryngoscopes. Hence, CMAC D-blade is preferred in simulated cervical spine injury where intubator needs to maintain a neutral neck position. However, intubation time may be significantly longer due to difficulty in negotiating the endotracheal tube pass vocal cord and impingement of endotracheal tube to the anterior wall of trachea. There is a study published Glidescope which is also a hyperangulated videolaryngoscope suggested that obtaining a partial glottic view of larynx may facilitate a faster and easier tracheal intubation when compare to a full glottis view. The aim of this study is to clinically evaluate the time of tracheal intubation in relation to the full glottic view vs. partial glottic view which is deliberately obtained when using CMAC D-blade video laryngoscopy in simulated cervical spine injury.

Detailed Description
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Direct laryngoscope requires proper alignment of the oro-pharyngeal-laryngeal axis to provide the best laryngeal view for intubation. In cervical spine patients, this alignment is not possible resulting in an increased risk of failed intubations. Difficult intubation and failed tracheal intubation are among the major causes of morbidity and mortality associated with anesthesia. In recent years, video laryngoscope has played an increasingly important role in the management of patients with unanticipated difficult or failed endotracheal intubation. When compared with a direct laryngoscope, the video laryngoscope achieved a better view of the glottis and a high rate of successful intubation. On comparing the C-MAC with the conventional Macintosh blade, a conventional C-MAC Macintosh blade 3 and D-blade have a blade angulation of 18° and 40° in the D-blade respectively. In addition, with D-blade is an elliptically tapered blade-shaped rising to distal. This highly angulated C-MAC D blade provides a better glottic visualization in comparison to the direct laryngoscopes and in simulated cervical spine injury. This resulted in successful intubation in routine induction of anesthesia and rescue intubation in patients with difficult airway with C-MAC D Blade. But in terms of intubation time, study has shown a significantly shorter time with C-MAC D Blade compared with other indirect laryngoscopes. This may be due to a common problem seen in indirect video laryngoscopy whereby a good glottic view does not always allow advancing the tube into the trachea. A study has been conducted on Glidescope which is also a hyperangulated blade suggested that obtaining a partial glottic view of larynx may facilitate a faster and easier tracheal intubation when compare to a full glottis view. Randomised controlled trial also showed that GlideScope and C-MAC D blade video laryngoscope using manual inline axial stabilization (MIAS) for tracheal intubation in patients with cervical spine injury/pathology were equally efficacious. The aim of this study is to clinically evaluate the time of tracheal intubation in relation to deliberately obtained full glottic view vs. partial glottic view when using CMAC D-blade video laryngoscopy in simulated cervical spine injury.

Official Title
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A Randomized Controlled Trial Comparing Full Glottis View vs. Partial Glottis View During Intubation Using CMAC D-Blade Video Laryngoscope in Simulated Cervical Injury Patient

Conditions
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Intubation; Difficult or Failed, Airway Complication of Anesthesia

Intervention / Treatment
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* Device: CMAC D-blade videolaryngoscope with full or partial glottic view


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: All patients with American Society of Anaesthesiologist (ASA) physical status I-III Age (≥21-75 years old) General anaesthesia requiring tracheal intubation Provide written consent to participate in the study Exclusion Criteria: Pregnancy Body mass index (BMI) ≥ 35 Condition requires rapid sequence induction Need for fibreoptic intubation Need for nasal intubation Documented difficult airway during previous surgery Recent (3 months) active ischemic heart disease Recent (3 months) cerebrovascular disease Acute exacerbation of respiratory disease (eg. Uncontrolled asthma, Chronic Obstructive Pulmonary Disease)

Ages Eligible for Study
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Minimum Age: 21 Years
Maximum Age: 75 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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Full glottic view on CMAC- D blade<br>Deliberately obtaining a full glottis view is deﬁned as negotiation and advancement of CMAC D blade tip positioned at the vallecula. Occasionally, external laryngeal pressure may be needed to assist in obtaining a full glottic view. The full glottic view is defined as a percentage of glottic opening (POGO) approximate 100%. | Device: CMAC D-blade videolaryngoscope with full or partial glottic view<br>* Deliberate achieving full or partial glottic view on C MAC D-blade video laryngoscope and comparing time and ease of intubation with both arms<br>|
| Active Comparator: Partial glottic view on CMAC- D blade<br>The partial glottis view is deﬁned as a percentage of glottic opening <50%. This is achieved by deliberately position the CMAC D-blade tip proximally away from the vallecular. | Device: CMAC D-blade videolaryngoscope with full or partial glottic view<br>* Deliberate achieving full or partial glottic view on C MAC D-blade video laryngoscope and comparing time and ease of intubation with both arms<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Intubation time | This is the time taken from CMAC laryngoscope blade passes patient's lip until the recording of first end tidal CO2 (EtCO2); assessed up to 120 seconds. | during the intervention | 
| First attempt successful intubation attempt | First intubation attempt success rate between two groups; assessed up to maximum 2 attempts | during the intervention | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time to obtain glottic view | Time taken for from CMAC laryngoscope blade passes patient's lip until achieving assigned laryngoscopic view; assessed up to 120 seconds | during the intervention | 
| Hemodynamic changes | Blood pressure, mean arterial pressure and heart rate recorded 1 min, 2.5 min then 5 min post intubation | immediately after the intervention | 
| Airway trauma | Incidence of oral mucosal trauma, lip laceration, dental laceration; assessed up to discharge from operating theatre. | immediately after the surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Glottic view, Intubation time, C MAC D- blade