The evaluation of a better intubation strategy when only the epiglottis is visible: a randomized, cross-over mannequin study

BACKGROUND: The Cormack-Lehane (C-L) grade III airway is considered to be a challenging airway to intubate and is associated with a poor intubation success rate. The purpose of this study was to investigate whether the holding position, shapes, bend angles of the endotracheal tube (ET) and the stylet-assisted lifting of the epiglottis could improve the success rate of intubation. METHODS: Thirty-two participants, 26 physicians, 2 residents, and 4 nurse practitioners, with 12.09 ± 5.38 years of work experience in the emergency department and more than 150 annual intubation events, were enrolled in this randomized, cross-over mannequin study. We investigated the effects of straight-to-cuff ET shapes with 35° and 50° bend angles, banana-shaped ET with longitudinal distances of 28 cm and 26 cm, two methods of holding the ET (either on the top or in the middle), and lifting or not the epiglottis, on the intubation duration, its success rate, and its subjective difficulty. The aim of the study is to provide optimized intubation strategies for difficult airway with C-L IIb or III grades, when the inlet of the trachea cannot be visualized. RESULTS: The two groups that lifted the epiglottis using the stylets, in bend angles of 35° and 50°, had the shortest duration of intubation (23.75 ± 14.24 s and 20.72 ± 6.90 s, hazard ratios 1.54 and 1.85 with 95% confidence intervals [95% CI] of 1.01–2.34 and 1.23–2.78, respectively) and a 100% success rate in intubations. In the survival analysis, lifting of the epiglottis was the only significant factor (p < 0.0001, 95% CI 1.34–2.11) associated with the success rate of intubation. CONCLUSIONS: The use of the epiglottic lift as an adjunctive technique can facilitate the intubation and improve its success rate without increasing procedure difficulty, in C-L III airway, when only the epiglottis is seen. TRIAL REGISTRATION: ClinicalTrials Registry (https://clincaltrials.gov, identifier NCT03366311). ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12871-018-0663-9) contains supplementary material, which is available to authorized users.