• Dorna Kheirabadi, Azim Honarmand, Mohammad R Rasouli, Mohammad R Safavi, and Mohammad R Maracy.
• Anesthesiology and Intensive Care Research Center, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
• Minerva Anestesiol. 2022 Mar 1; 88 (3): 114-120.

BackgroundPrediction of difficult intubation (DI) has remained challenging for anesthesiologists and validity of airway assessment tests has not been fully investigated. This study aims to compare predictive values of these tests for prediction of DI in obese patients.MethodsOne hundred ninety-six patients with Body Mass Index (BMI) ≥30 kg/m2 were included in this prospective study. Variables including intubation Difficulty Scale (IDS), thyromental height (TMH), hyomental distance (HMD) in extent and neutral neck position, HMD ratio (HMDR), sternomental distance (SMD), thyromental distance (TMD), ratio of height to TMD (RHTMD), width of mouth opening (MO), mandibular length (ML), Cormack-lehane (C-L) grade, upper lip bite test (ULBT), history of snoring, and obstructive sleep apnea were collected. Multiple logistic regression and receiver operating characteristic (ROC) curve analysis were used to determine independent predictors of DI (defined as IDS≥5) and their cut off points.ResultsDI and difficult laryngoscopy (defined as C-L grade ≥3) were observed in 23% and 24.5% of the study population, respectively. Multiple logistic regression identified TMH (Odds ratio (OR):0.28, 95% confidence interval (CI):0.14-0.58, P=0.001), BMI (OR:1.18, 95% CI: 1.11-1.26, P<0.001), HMDR (OR:0.45, 95% CI:0.36-0.56, P<0.001) and ULBT (OR: 3.91, 95% CI: 2.14-7.14, P<0.001) as independent predictors of DI. Sensitivity of TMH<4.8 cm, BMI>34.9 kg/m2, HMDR<1.4 and ULBT class ≥2 were determined as 75.1%, 73.3%,62.3% and 93.3% respectively.ConclusionsTMH and ULBT had the highest sensitivity for prediction of DI in obese patients in this study and it is recommended to be considered as part of airway assessment in this patient population.

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