Correlation of bispectral index and Richmond agitation sedation scale for evaluating sedation depth: a retrospective study

Background: This study aims to verify the correlation of bispectral index (BIS) and Richmond agitation sedation scale (RASS) for evaluating these and explore possibility of replacing RASS with BIS.

Methods: This retrospective cohort study consisted of 74 patients who were collected from the third Intensive Care Unit (ICU) ward of XXX Hospital between May 2012 and June 2015 in this retrospective study. Sedation levels were evaluated using the 10-grade RASS and were continuously monitored with a BIS monitor during the procedure every 5 minutes. BIS values and RASS scores were recorded.

Results: Patients were divided into dexmedetomidine (n=31) and midazolam (n=43) groups, and 342 paired data were collected. A statistically significant correlation existed between BIS values and RASS scores either in all patients undergoing flexible fiberoptic bronchoscopy (FFB) or in dexmedetomidine and midazolam groups at different time points. Correlation coefficient was higher in midazolam group compared with dexmedetomidine group at different time points (P<0.05).

Conclusions: A correlation was observed between BIS and RASS for evaluating depth of sedation in ICU patients undergoing FFB (P<0.05). Study results indicated that BIS monitoring is a meaningful tool, which can be applied as an adjunctive and alternative method to assess sedation, especially for high-risk patients who are prone to be under- or over-sedation.