To the Editor,
We congratulate Dr. Gu et al. for their sound, thought-provoking article that addresses the issue of optimizing intubation conditions during video laryngoscopy by purposely using a restricted laryngeal view.1
Teaching direct laryngoscopy generally focuses on obtaining the best possible glottic view, with the ease of intubation generally being directly proportional to this view. Unlike direct laryngoscopy, however, the authors have shown that a deliberately restricted view of the glottis when using GlideScope© GVL video laryngoscopy is associated with both improved ease and decreased time to endotracheal intubation - in essence, the ease of intubation was inversely proportional to the quality of the glottic view.
The authors’ findings may have a significant impact on the interpretation and conclusions of video laryngoscopy research that uses the glottic view [e.g., modified Cormack-Lehane2 or POGO (percentage of glottic opening) score],3 as a surrogate end point for ease of intubation.4 This assumption may simply not be the case. The authors’ findings may also have a significant impact on optimizing teaching of video laryngoscopy skills. Perhaps we should curb our enthusiasm about obtaining the best view of the glottis and, instead, emphasize that this approach is a complete departure from what is currently being taught regarding direct laryngoscopy. It raises the question as whether, given their findings, we should reject the view of the glottis as a surrogate end point for intubation in articles about video laryngoscopy.
It is exciting to see video laryngoscopy research maturing beyond simply the direct laryngoscopy vs video laryngoscopy paradigm into how best to optimize endotracheal intubation when we have access to both techniques. Just as video laryngoscopy and direct laryngoscopy are different but complementary techniques, it is not surprising that their optimal research and teaching approaches may differ as well.
References
Gu Y, Robert J, Kovacs G, et al. A deliberately restricted laryngeal view with the GlideScope® video laryngoscope is associated with faster and easier tracheal intubation when compared with a full glottic view: a randomized clinical trial. Can J Anesth 2016. DOI:10.1007/s12630-016-0654-6.
Samsoon GL, Young JR. Difficult tracheal intubation: a retrospective study. Anaesthesia 1987; 42: 487-90.
Levitan RM, Ochroch EA, Kush S, Shofer FS, Hollander JE. Assessment of airway visualization: validation of the percentage of glottic opening (POGO) scale. Acad Emerg Med 1998; 5: 919-23.
Griesdale DE, Liu D, McKinney J, Choi PT. Glidescope® video-laryngoscopy versus direct laryngoscopy for endotracheal intubation: a systematic review and meta-analysis. Can J Anesth 2012; 59: 41-52.
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This submission was handled by Dr. Hilary P. Grocott, Editor-in-Chief, Canadian Journal of Anesthesia.
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This letter is accompanied by a reply. Please see Can J Anesth 2016; 63: this issue.
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Duggan, L.V., Brindley, P.G. Deliberately restricted laryngeal view with GlideScope® video laryngoscope: ramifications for airway research and teaching. Can J Anesth/J Can Anesth 63, 1102 (2016). https://doi.org/10.1007/s12630-016-0681-3
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DOI: https://doi.org/10.1007/s12630-016-0681-3