Comparison of Video Laryngoscope Using Miller or Macintosh Approach During Endotracheal Intubation

Study Overview
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Brief Summary
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Video laryngoscope has become recommended option during difficult intubation. Guidelines of ASA at 2013 had suggested using video laryngoscope after failure intubation of direct laryngoscope. Varieties of video laryngoscope had been invented with different curves. We call the one which has the same curve of Macintosh laryngoscope as conventional video laryngoscope in this study. Mostly, the way of using conventional video laryngoscope is suggested as Macintosh method. However, with the front positioning camera, Miller method can theoretically improve the glottic opening. We intend to discuss whether using Miller approach with conventional video laryngoscope can improve glottic opening or not.

Detailed Description
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Video scope can provide better glottic opening by increase the tilting angle of the tip, and the position of camera can provide larger vision angle. However, while the angle increases, the endotracheal tube must fallow the curve, which may require learning curve of the operator. In Glidescope as example, increase the tilting angle can help with glottic exposure, however the steep curve will simultaneously increase the difficulty of inserting the tube or using Magill forceps, especially while intubating double lumen or nasal endotracheal tube. Conventional video laryngoscope in this study indicates the video laryngoscope blade which has the same curve as Macintosh laryngoscope. It mainly improves the glottic view by front positioning camera. Anesthesiologist usually place the tip of the blade at vallecula to expose the glottic which is the conventional ways of using Macintosh blade which we name it as Macintosh method. Placing the tip below the epiglottis and lift it up directly is the way of using Miller blade. Theoretically, the Miller method with conventional video laryngoscope may improve the scale of glottic exposure measured with Cormack-Lehane grade. This is a one-group pretest-posttest study to compare the Cormack-Lehane grade with two different methods in the same patient. This study tends to discuss whether this combination can improve the glottic exposure and preserve the advantage of direct laryngoscope.

Official Title
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Comparison of Video Laryngoscope Using Miller or Macintosh Approach During Endotracheal Intubation

Conditions
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Difficult Intubation

Intervention / Treatment
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* Procedure: Video laryngoscope with Miller approach


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Aged>20 Scheduled to received operation that required general anesthesia with endotracheal tube [3] ASA I, II Exclusion Criteria: Emergent surgery pregnant Limited mouth opening Poor dental condition Airway obstruction (oral tumor, hypopharyngeal cancer….etc) Deep neck infection Allergic to any anesthetic

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
Intervention Model: Single Group Assignment
Interventional Model Description: one-group pretest-posttest study
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Intubation with Miller approach<br>Posttest group: Patient receive intubation with conventional video laryngoscope with Miller approach. Pretest group: Patient receive intubation with conventional video laryngoscope with Macintosh approach. | Procedure: Video laryngoscope with Miller approach<br>* Miller approach indicates lifting epiglottis during laryngoscopy, which is the way of using Miller laryngoscope<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change of cormack lehane grade | Compare the difference of cormack lehane grade using Macintosh ot Miller approach.(cormack lehane grade has four gradings. Grade 1 represent entire glottic opening. Grade 4 represent vocal cord cab not be seen) | Measured from glottic exposed by Macintosh approach to Miller approach. Record the cormack lehane grade. The whole precess will be completed within 5 minutes if there are no difficult intubation. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Post intubation adverse event | Some adverse events are often seen after intubation, such as sore throat, hoarseness....etc. | Visit the patient daily at post operation day 1 and record any adverse event until post operation day3 or the patient is discharged. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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difficult intubation, video laryngoscope