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Minerva Anestesiologica 2015 August;81(8):846-54


language: English

Indirect videolaryngoscopy using Macintosh blades in patients with non-anticipated difficult airways results in significantly lower forces exerted on teeth relative to classic direct laryngoscopy: a randomized crossover trial

Pieters B. 1, 2, Maassen R. 3, Van Eig E. 4, Maathuis B. 4, Van Den Dobbelsteen J. 4, Van Zundert A. 2, 5, 6

1 Department of Anesthesiology, Intensive Care and Pain Therapy, Catharina Hospital Eindhoven, Eindhoven, The Netherlands; 2 Department of Anesthesiology, Maastricht University Hospital, Maastricht, The Netherlands; 3 Department of Anesthesiology, Laurentius Hospital Roermond, Roermond, The Netherlands; 4 Delft University of Technology, Delft, The Netherlands; 5 Department of Anesthesiology, Faculty of Medicine, University Ghent Hospital, Ghent, Belgium; 6 Department of Anesthesiology and Perioperative Medicine, University of Queensland; 7 School of Medicine, Royal Brisbane and Women’s Hospital, Herston Brisbane, Australia


BACKGROUND: Videolaryngoscopy has proven advantageous over direct laryngoscopy for a variety of outcome variables, most importantly, making laryngoscopy more successful. We tested whether three videolaryngoscopes (VLS), McGrath® series 5 (Aircraft Medical Ltd, Edinburgh, UK), C-MAC® (Karl Storz, Tuttlingen, Germany) and GlideScope® Cobalt (Verathon Medical, Bothell, WA, USA) exert reduced forces on maxillary incisors and lower teeth, and compared them with a classic Macintosh MAC 3 laryngoscope blade during laryngoscopy.
METHODS: In this randomized crossover trial, we included 141 patients (ASA I-III) with non-anticipated difficult airways. They were randomly allocated to undergo direct laryngoscopy and videolaryngoscopy performed with one of three VLS. Primary outcome was the magnitude of forces applied to the maxillary incisors during laryngoscopy. Secondary outcomes were the frequency with which forces were applied, and the magnitude of forces applied to the lower teeth.
RESULTS: Forces applied to the maxillary incisors during direct classic laryngoscopy were on average higher than forces applied during videolaryngoscopy. Among the VLS the average force applied was significantly lower for the C-MAC® as compared to the McGrath® and the GlideScope® VLS. The frequency with which a force was applied to the maxillary incisors was significantly lower for the C-MAC®, compared to the other VLS and classic Macintosh laryngoscope. The number of cases in which force was applied to the lower teeth was smallest for the McGrath VLS.
CONCLUSION: Forces exerted on maxillary incisors are lower using video-assisted Macintosh blade laryngoscopy compared to classic direct laryngoscopy. The number and magnitude of forces applied to maxillary incisors also differ substantially between different VLS.

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