Exploring the impact of augmenting sedation assessment with physiologic monitors

Pharmacological sedation is a necessary tool in the management of critically ill, mechanically ventilated patients. The intensive care unit (ICU) sedation strategy is to use the least amount of medication to meet safety and comfort goals. Titration of pharmacological agents is currently guided by clinical assessment tools. The purpose of this study was to determine whether the addition of a neurophysiological monitor, bispectral index (BIS), aided the ICU nurse in reducing the amount of drug used, compared to a clinical tool alone, in a general critical care population.

In this prospective clinical trial, mechanically ventilated adults (N=300) were randomised to sedation assessment using only the observational assessment tool (RASS) or a combination of observational and physiologic measures (RASS+BIS). Subjects were enrolled from a medical ICU (N=154), a trauma ICU (N=72) and a general mixed-use ICU (N=74).

BIS-augmented sedation was only associated with the reduction of drug use when patients were sedated with propofol or narcotic agents (propofol [1.61 mg/kg/h vs. 1.77 mg/kg/h; p<0.0001], fentanyl [54.73 mcg/h vs. 66.81 mcg/h; p<0.0001], and hydromorphone [0.97 mg/h vs. 4.00 mg/h: p<0.0001] compared to RASS alone. In contrast, patients sedated with dexmedetomidine or benzodiazepines were given higher doses under the BIS-augmented dexmedetomidine [0.46 mcg/kg/h vs. 0.33 mcg/kg/h; p<0.0001], lorazepam [4.13 mg/h vs. 3.29 mg/h p<0.0001], and midazolam [3.73 mg/h vs 2.86 mg/h; p<0.0001]) protocol compared to clinical assessment alone.

The clinical evaluation of depth of sedation remains the most reliable method for the titration of pharmacological sedation in the critical care unit. However, BIS-augmented assessment is helpful in reducing the amount of propofol and narcotic medication used and may be considered an adjunct when these agents are utilised.