[Outdoor performance of different videolaryngoscopes on a glacier: a manikin study].

Objectives: Little information about the performance of videolaryngoscopes outdoors is available. We aimed to test the hypothesis that a Macintosh direct laryngoscope would perform less well than videolaryngoscopes under difficult environmental conditions (high-altitude glacier, sun-reflecting snow).

Material And Methods: After local research ethics committee approval, this randomized controlled trial enrolled 20 physicians who intubated manikins with limited cervical extension mouth opening under 5 conditions: 1) in hospitals (indoors), 2) indoors at a high altitude, 3) outdoors on a glacier in sunlight without sunglasses, 4) outdoors on a glacier with sunglasses, and 5) outdoors on a glacier with the physician and manikin covered with a blanket. The following devices were compared to the Macintosh laryngoscope, McGrath, Airtraq-SP, GlideScope, KingVision, C-MAC-D-Blade, AP Advance Difficult Airway Blade and Bonfils. The main outcome was first-attempt intubation success; secondary outcomes were intubation time, visibility on the screen, and view of the glottis.

Results: The best intubation success rates were observed indoors asnd on the glacier under a blanket. The Macintosh performed better than the videolaryngoscopes under bright sunlight. We observed significant differences in the performance of devices with built-in screens under varying conditions. Wearing sunglasses improved performance with some but not all devices. Intubation times differed significantly between devices, regardless of the environmental condition (P<0.01). Screen visibility differed significantly between conditions and devices.

Conclusion: Successful intubation with videolaryngoscopes is less likely under bright sunlight conditions. The Macintosh laryngoscope performs better than videolaryngoscopes. Covering the heads of both the physician and the patient with a dark blanket sufficiently overcomes the detrimental effects of sunlight during intubation.