• Yu-Ming Wu, Yen-Hao Su, Shih-Yu Huang, Chien-Wun Wang, Shih-Chiang Shen, Jui-Tai Chen, Po-Han Lo, Yih-Giun Cherng, Hsiang-Ling Wu, and Ying-Hsuan Tai.
• Department of Anesthesiology, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan, ROC.
• J Chin Med Assoc. 2022 May 1; 85 (5): 571-577.

BackgroundObese people have a higher risk of difficult laryngoscopy due to their thick neck, large tongue, and redundant pharyngeal soft tissue. However, there is still no established predictive factor for difficult laryngoscopy in obese population.MethodsWe conducted a prospective assessor-blind observational study to enroll adult patients with a body mass index of 30 kg·m-2 or higher undergoing laparoscopic sleeve gastrectomy at a medical center between May 2020 and August 2021. Conventional morphometric characteristics along with ultrasonographic airway parameters were evaluated before surgery. The primary outcome was difficult laryngoscopy, defined as a Cormack and Lehane's grade III or IV during direct laryngoscopy. Logistic regression analyses were performed to evaluate the association between included factors and difficult laryngoscopy. Discrimination performance of predictive factors was assessed using area under the receiver operating characteristic curve (AUC).ResultsA total of 80 patients were evaluated, and 17 (21.3%) developed an event of difficult laryngoscopy. Univariate analyses identified five factors associated with difficult laryngoscopy, including age, sex, hypertension, neck circumference, and cross-sectional area of tongue base. After adjusting for these variables, neck circumference was the only independent influential factor, adjusted odds ratio: 1.227 (95% confidence interval, 1.009-1.491). Based on Youden's index, the optimal cutoff of neck circumference was 49.1 cm with AUC: 0.739 (sensitivity: 0.588, specificity: 0.889; absolute risk difference: 0.477, and number needed to treat: 3).ConclusionGreater neck circumference was an independent risk factor for difficult laryngoscopy in obese patients. This finding provides a way of reducing unanticipated difficult airway in this high-risk population.Copyright © 2022, the Chinese Medical Association.

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