Efficacy of inserting a flexible bronchoscope to a predetermined depth for orotracheal intubation by inexperienced personnel: a randomized-controlled study

PURPOSE: Bronchoscopic tracheal intubation is an indispensable technique in patients with difficult airway, but it is often difficult, particularly for less-experienced anesthesiologists, to obtain a view of the glottis by bronchoscopy. We hypothesized that insertion of a flexible bronchoscope to a predetermined depth would facilitate bronchoscopic intubation. METHODS: Fifty anesthetized patients were randomly allocated to two groups, and inexperienced anesthesiologists either inserted a bronchoscope along the center of the tongue (in group C), or along the hard palate to a predetermined depth based on the mouth-to-tragus distance (in group S). The success rate of obtaining a bronchoscopic view of the glottis (primary outcome) and other factors were compared. RESULTS: The success rate of obtaining a bronchoscopic view of the glottis was significantly higher in group S (24 of 25 patients) than in group C (17 of 25 patients) (P = 0.02; 95%CI for difference: 8 - 48%]). The success rate of tracheal intubation was significantly higher in group S (18 of 25 patients) than in group C (8 of 25) (P = 0.01). Time to glottic visualization was significantly shorter in group S (24 [14 - 40] s) than in group C (49 [30 - 120]] s) (P = 0.003), and apnea time was significantly shorter in group S (81 [52 - 120] s) than in group C (120 [109 - 120] s) (P = 0.004). CONCLUSIONS: Insertion of a bronchoscope for the mouth-to-tragus distance would increase the success rate of bronchoscopic intubation, by facilitating to obtain a bronchoscopic view of the glottis. CLINICAL TRIAL REGISTRATION: jRCT1032250593.