Clinical impact of hypnotic-titration guidelines based on EEG Bispectral Index (BIS) monitoring during routine anesthetic care

Abstract

Study Objectives: To examine the impact on perioperative care of routine Bispectral Index (BIS) monitoring during general anesthesia throughout an entire operating room (OR) suite. Design: O pen, observational trial with retrospective analysis of guideline performance. Data were analyzed from 1,552 adult patients receiving general anesthesia with surgical times of at least 1 hour and who were extubated by postanesthesia care unit (PACU) discharge. Staff were trained using a simple decision matrix, which integrated BIS titration goals with anesthetic management. Unmonitored patients were compared to either BIS-monitored patients or to performance subgroups based on BIS measurements recorded during anesthetic maintenance (“deep”, BIS < 50; “target”, 50–65; “light”, >65). Setting: Large, urban academic/trauma center. Measurements and Main Results: Demographic profiles of all groups and subgroups were similar. Anesthetic emergence, recovery times, and volatile drug use were significantly shortened or reduced only when BIS values were maintained between 50 and 65. Extubation time from end of surgery decreased by 2.1 minutes from 5.7 ± 7 (37%); OR exit time decreased by 2.2 minutes from 9.3 ± 6 (24%); eligibility for phase 1 PACU discharge decreased by 4 minutes from 22 ± 42 (23%); and actual PACU discharge decreased by 15 minutes from 130 ± 78 (7%). PACU extubation frequency decreased from 6.9% to 2.6%. Modest decreases in total intraoperative drug use were noted with an increase in PACU analgesic administration. Conclusions: Routine application of BIS monitoring throughout an OR suite impacted clinical outcome only if guideline targets were met. BIS values within the last 30 minutes of surgery were not predictive of emergence or recovery. Hypnotic maintenance at BIS < 50 did not confer any clinical advantage over unmonitored cases. Anesthetic maintenance at BIS values between 50 and 65 was associated with shortened emergence and recovery from general anesthesia.