Role of the Bispectral Index in Sedation Monitoring in the ICU

Objective: To review and critique evidence for the use of the bispectral index (BIS) in intensive care unit (ICU) patients. Data Sources: A computer search of English-language articles in MEDLINE (1966–July 2005), International Pharmaceutical Abstracts (1971–July 2005), and Scientific Citation Index Expanded (1980–July 2005) was conducted. A manual search of abstracts was also performed using the key search terms BIS, sedation, and critical care. Study Selection and Data Extraction: Case series, letters, editorials, and clinical studies that evaluated BIS in ICU patients were considered for inclusion. Data Synthesis: Nineteen studies comparing the BIS with sedation scales were evaluated, revealing that the BIS trends lower with increasing sedation. The BIS appeared to correlate better when sedation scores were grouped rather than individual values. However, correlations between BIS and subjective scales were low in most studies (r2 0.21–0.93). Additionally, there was poor correlation between drug dosage and the BIS. Randomized, controlled trials demonstrating improved outcomes with BIS monitoring have not been reported. Conclusions: Interpreting literature on the usefulness of the BIS in the ICU is difficult for reasons that include heterogeneous populations, different methods of collecting BIS data, and use of different versions of BIS software and hardware. Outcomes data are lacking. The 2002 Society of Critical Care Medicine Sedation Guidelines recommendation that more data are needed before the BIS should be used routinely in the ICU remains unchanged. We recommend that further studies be conducted to determine the optimal method of obtaining BIS data and evaluate the impact of the BIS on relevant patient outcomes.