Evaluation of the upper lip bite test in predicting difficult laryngoscopy

Abstract

Study objective: To evaluate the accuracy of the upper lip bite test (ULBT) in predicting difficult laryngoscopy.

Design: Prospective, observational outcome study.

Setting: Operating room of a large tertiary-care academic medical center.

Patients: 6,882 consecutive adult, ASA physical status I, II, III, IV, and V patients, scheduled for procedures in all surgical specialties.

Interventions: Upper lip bite test class was determined for all patients preoperatively.

Measurements: The Cormack & Lehane grade of laryngeal view was determined at endotracheal intubation.

Main results: Only 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.

Conclusions: The 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.