Laryngoscopies in the Obese: Predicting Problems and Optimizing Visualization

Abstract

This pilot study was designed to 1) identify predictors of difficult laryngeal exposure in obese patients, 2) develop strategies for efficient intubation and intraoperative visualization of the glottis, and 3) devise perioperative protocols for difficult laryngoscopies. We undertook a retrospective study over a 1-year period of 14 consecutive patients with a body mass index of more than 30 kg/M2 who underwent elective direct laryngoscopy under general anesthesia. Measurements of height, weight, neck circumference, Mallampati score, and Cormack-Lehane classification of the airway were recorded. Problems encountered during anesthesia induction and emergence were also noted. The laryngologist recorded on a visual analog scale the degree of difficulty encountered in obtaining a binocular stereoscopic view and magnification, illumination, and suspension. Anatomic challenges during difficult laryngoscopy included decreased neck extension, redundant folds of tissue in the oropharynx and hypopharynx, and upper airway collapsibility. Overall, there was an association between the incidence of difficult laryngeal exposure and the Cormack-Lehane score (r = .57; p = .03), but the Mallampati score was of limited utility to the laryngologist. Neck size in female patients correlated with the Cormack-Lehane score (p = .02). Neither weight nor body mass index were predictive of a difficult laryngeal exposure. Straight blade laryngoscopes with a distal flange allowed greater depth of insertion and provided the best visualization of the glottis. An appropriate clinical examination may help predict a difficult airway. However, further studies are warranted to fully characterize the anatomic predictors of a difficult laryngeal exposure.