Optimal level of bispectral index for conscious sedation in awake fiberoptic nasotracheal intubation.

backgroundBispectral index (BIS) has been in practice as an objective tool to measure the depth of conscious sedation. The data on adequate levels for awake fiberoptic nasotracheal intubation (AFNI) is however scarce. We aimed to obtain an optimal level of BIS required for achieving the adequate conscious sedation in AFNI procedure.

methodsIn a prospective, observational, outcome assessor blinded cohort trial, 94 consecutive patients with anticipated difficult intubation and undergoing AFNI for any elective surgery were enrolled. The topical anesthesia and sedation were induced with lidocaine and dexmedetomidine, while keeping the patient awake. The sedation levels were targeted to BIS ≤90 and Ramsay sedation score (RSS)≥2 to attempt intubation. Propofol bolus were administered if patients get agitated. The primary outcome was "Stable BIS", the lowest BIS at which intubation could be feasibly performed. A receiver operator characteristic curve, Youden index, and correlation analysis were used.

resultsThe optimal criterion for BIS was obtained as ≤86 (AUC: 0.80, sensitivity 88.30%, specificity 61.45%, Youden index 49.74). The stable BIS ranged from 80 to 88, while RSS varied from 1 to 3. The BIS and RSS correlated significantly (r: 0.83). The stable BIS was independent of any baseline characteristics. Six patients had transient untoward events, none requiring any intervention.

conclusionBIS serves as an effective objective tool for titrating the depth of conscious sedation. We advocate a BIS range of 80-86 for feasibly performing the AFNI procedure.