Inadequate Sedation During Therapeutic Paralysis: Use of Bispectral Index in Critically Ill Patients

BACKGROUND Patients receiving therapeutic paralysis may experience inadequate sedation due to intrinsic limitations of behavioral sedation assessment. Bispectral index (BIS™) provides an objective measure of sedation; however, the role of BIS™ is not well defined in intensive care unit (ICU) patients on neuromuscular blocking agents (NMBA). OBJECTIVE The aim of this study was to delineate the relationship between BIS™ and level of sedation for critically ill patients during therapeutic paralysis. METHODS This was a retrospective observational study conducted in ICU patients receiving continuous infusion NMBA and BIS™ monitoring. The primary endpoint was the correlation of BIS™ <60 during therapeutic paralysis with a Richmond Agitation Sedation Score (RASS) of -4 to -5 (i.e., deep or unarousable sedation) at the time of emergence from therapeutic paralysis. RESULTS Thirty-one patients were included in the analysis. Three of these patients (9.6 %) were inadequately sedated upon emergence from paralysis; that is, restless or agitated (RASS +1 to +2). We did not observe a correlation between BIS™ and RASS upon emergence from paralysis (r = 0.27, p = 0.14). The sensitivity of BIS™ <60 in predicting deep sedation (RASS -5 to -4) was 100 % (95 % confidence interval [CI] 0-100) with a positive predictive value of 35.7 %. The sensitivity and positive predictive value of BIS™ <60 in predicting light sedation or deeper (RASS -5 to -2) was 92.9 % (95 %CI 83.3-100) and 92.9 %, respectively. CONCLUSION These results suggest that 1 in 10 critically ill patients receiving therapeutic paralysis may be inadequately sedated. BIS™ monitoring may serve as a useful adjunctive measure of sedation in critically ill patients receiving therapeutic paralysis.