Utility of Bispectral Index (BIS) Monitoring During Nurse-Administered Propofol Sedation (NAPS) for Outpatient Upper Endoscopic Ultrasound (EUS): A Prospective, Randomized, Single-Blinded Comparative Study

Abstract

Background: BIS is a quantitative assessment of cortical activity that has been used to guide sedation during EGD and colonoscopy. Its use for EUS has not yet been defined. Objective: To determine the impact of BIS-guided NAPS compared to standard NAPS (control group) for total drug doses and recovery of outpatients undergoing EUS. We hypothesized that compared to standard NAPS, BIS-guided NAPS would decrease by ≥20% both the recovery time and propofol dose required. Methods: Prospectively, outpatients undergoing upper EUS and eligible for propofol sedation were randomly assigned to BIS-guided or standard NAPS administered in intermittent boluses by experienced RNs. While assessing patient movement and respiratory effort, the RN titrated BIS-guided deep sedation to a target BIS score of <80. For standard NAPS, the RN was blinded to BIS scores and sedation for this group was titrated to a MOAAS score ≤3. All data during EUS and recovery were recorded by an additional observer. BIS scores for all patients were calculated using EEG signals (measured from an applied four-array electrode sensor) processed by the Aspect A-2000™ BIS-XP monitoring system. Results: Of 50 patients enrolled, data for 44 (24 M/20 F; 24 BIS-guided/20 control) were evaluable. For BIS-guided and standard NAPS respectively, no significant differences were noted for patient demographics, mean procedure duration (28 min vs. 34 min), total propofol dose used (488 mg vs. 543 mg), or recovery duration (26.5 min vs. 23 min), all p > 0.19. For the same respective groups, there were also no significant differences in mean intraprocedural MOAAS (1.21 vs. 1.26) or BIS scores (58.7 vs. 60.4), all p > 0.13. Mean BIS scores were similar between both groups at initial endoscope insertion, withdrawal, and at timed intervals during the procedure. All measured study variables remained similar when the two study groups were subdivided chronologically by EUS date into 2 or 3 equally-sized patient groups (all p > 0.09). Conclusion: Compared to standard NAPS for outpatient upper EUS, BIS-guided NAPS offers no statistically significant decrease in post-procedure recovery times or total propofol doses used. The intraprocedural BIS scores were similar between both groups, which may be due to frequent patient immobility as required during diagnostic and therapeutic EUS. We found that a target BIS score of 60-65 is required to routinely complete upper EUS exams (particularly during EUS-FNA) when guided by multiple assessment endpoints. More studies are required to determine the role of focused BIS-guided NAPS for outpatient EUS. This study was supported by a grant from Aspect Medical Systems, Inc.