The utility of the bispectral index in procedural sedation with propofol in the emergency department

Abstract

The bispectral index (BIS) may be a useful monitor to predict the level of awareness in patients undergoing procedural sedation in the emergency department (ED).

Objectives: The authors hypothesized that using the BIS during procedural sedation in the ED would increase the recognition of adequately sedated patients, thus reducing oversedation and the corresponding increased rate of respiratory depression (RD). As a result, the occurrence of RD would be reduced.

Methods: This was a prospective randomized study of ED procedural sedation with propofol. Sedations were randomized to have the treating physician either blinded or not blinded to information from the BIS monitor. Vital signs, pulse oximetry, end-tidal carbon dioxide (ETCO(2)), propofol dosage, and the BIS score were recorded. RD was defined as a change in ETCO(2) greater than 10 mm Hg, an oxygen saturation of less than 90% at any time, or an absent ETCO(2) waveform. The RD rates were compared with chi-square tests.

Results: One hundred five patients were enrolled in the study; five were excluded due to study protocol violations. No serious adverse events were reported. RD was seen in 29 of 100 (29%) patients; 18 of 48 in the BIS-blinded group and 11 of 52 in the BIS-unblinded group had RD (p = 0.06). For patients requiring only a single dose of propofol, three of 15 in the BIS-blinded group and four of 18 in the BIS-unblinded group met the criteria for RD (p = 0.87). For patients requiring multiple doses of propofol, 15 of 33 patients in the BIS-blinded group and seven of 34 patients in the BIS-unblinded group met criteria for RD (p = 0.02). The mean BIS nadir for BIS-blinded patients was 60.9 (95% CI = 56.9 to 65.0) and that for BIS-unblinded patients was 63.2 (95% CI = 57.7 to 65.3) (p = 0.22).

Conclusions: There was a lower rate of RD when physicians had access to the BIS during procedural sedations. This difference was greater in sedations requiring multiple doses of propofol. There was no difference in the rate of RD when only a single dose was given.