Evaluation of the upper lip bite test in predicting difficult laryngoscopy

Study ObjectiveTo evaluate the accuracy of the upper lip bite test (ULBT) in predicting difficult laryngoscopy.DesignProspective, observational outcome study.SettingOperating room of a large tertiary-care academic medical center.Patients6,882 consecutive adult, ASA physical status I, II, III, IV, and V patients, scheduled for procedures in all surgical specialties.InterventionsUpper lip bite test class was determined for all patients preoperatively.MeasurementsThe Cormack & Lehane grade of laryngeal view was determined at endotracheal intubation.Main ResultsOnly 171 patients had ULBT class III, predicting a difficult laryngoscopy, while 173 patients presented with a Cormack & Lehane grade of 3 or 4. Of the 173, 14 patients had a previous ULBT class of III. Sensitivity and positive predictive value of the ULBT were 8.1% and 8.2%, respectively.ConclusionsThe ULBT is a poor predictor of difficult laryngoscopy when used as the single bedside screening test in a North American patient population. Its use cannot be recommended.