Pre-operative transnasal endoscopy as a predictor of difficult airway A prospective cohort study

BACKGROUND Consequences of failed endotracheal intubation can be catastrophic and predicting difficulty is therefore a critical issue. There is no consensus on the best way to predict difficulty. OBJECTIVE To evaluate the role of transnasal flexible endoscopic laryngoscopy (TFEL), a minimally invasive procedure, in the prediction of difficult intubation. DESIGN Prospective cohort study. SETTING San Raffaele Hospital, Milan, a tertiary university hospital. PATIENTS One hundred and sixty nine adults scheduled for elective ear, nose and throat surgery under general anaesthesia with pre-operative TFEL. INTERVENTION In addition to routine pre-operative evaluation by an anaesthesiologist, glottis exposure during TFEL was assessed with a scoring system similar to the modified Cormack-Lehane (MCL). MAIN OUTCOME MEASURES The extent to which TFEL improves the prediction of difficult direct laryngoscopy, measured with the MCL score, and of difficult intubation, measured with the intubation difficulty scale score. RESULTS When added to bedside evaluation, TFEL performed during tongue protrusion significantly (P = 0.005) improved the prediction of MCL. The area under the receiver operating characteristics curve was 0.75 [95% confidence interval (CI) 0.67 to 0.83] vs. 0.65 (95% CI 0.58 to 0.74). For the intubation difficulty scale (P = 0.049), the area under the receiver operating characteristics curve was 0.70 (95% CI 0.61 to 0.80) vs. 0.66 (95% CI 0.58 to 0.74). CONCLUSION TFEL is a useful tool in predicting difficult intubation, improving predictability of routine bedside evaluation.