Efficacy of bispectral monitoring as an adjunct to nurse-administered propofol sedation for colonoscopy: a randomized controlled trial

Abstract

Background and aims: Bispectral (BIS) monitoring provides an objective, non-invasive measure of the level of consciousness in sedated patients. BIS has been shown to lag behind the level of sedation during induction and emergence of sedation with propofol. In this study, we sought to determine whether BIS is a useful adjunctive maneuver to registered nurse-administered propofol sedation (NAPS) as measured by reductions in recovery time and doses of propofol administered.

Methods: A randomized controlled trial of 102 outpatients presenting for colonoscopy was performed. BIS values were recorded continuously in all subjects. Patients were randomized to receive NAPS with BIS visible to nurse and endoscopist versus BIS invisible to nurse and endoscopist. In phase 1 (47 patients), the nurse and endoscopist team were instructed to consider BIS (when visible) as only adjunctive information with regard to titrating sedation. In phase 2 (55 patients), the nurse endoscopist team was instructed to use BIS as the primary endpoint for titration of sedation, and to target BIS to greater than 60 (60-70 is deep sedation).

Results: In phase 1, the mean (SD) BIS value from scope-in (SI) to scope-out (SO) for BIS was 59.3 (9.9) and was not different from controls at 59.9 (10.1; p= 0.82). The mean (SD) propofol dose (mg/min) was 15.8 (5.6) and 17.2 (6.2) for BIS and controls, respectively (p= 0.45). The mean (SD) recovery time with BIS visible in phase 1 was 20.6 min (5.5) versus 19.2 min (4.5) in controls (p= 0.34). In phase 2, the mean (SD) BIS from SI to SO in those randomized to have BIS visible was 64.1 (5.4) versus 63.1 (8.5) in controls (p= 0.58). The mean (SD) dose of propofol (mg/min) was 16.1 (11.2) and 16.4 (12.3) for BIS and control groups, respectively (p= 0.92). The mean (SD) recovery time in phase 2 with BIS visible was 18.7 (3.5) versus 20.1 (5.6) in controls (p= 0.27).

Conclusions: BIS did not lead to reductions in mean propofol dose or recovery time when used as an adjunct to NAPS for colonoscopy, or when used as the primary target for sedation. No clinically important role for BIS monitoring as an adjunct to NAPS has yet been established.