A randomized evaluation of bispectral index-augmented sedation assessment in neurological patients

Abstract

Objective: To assess whether monitoring sedation status using bispectral index (BIS) as an adjunct to clinical evaluation was associated with a reduction in the total amount of sedative drug used in a 12 h period.

Design: Prospective randomized controlled clinical trial.

Setting: Tertiary care neurocritical care unit.

Patients: Sixty-seven mechanically ventilated adult patients receiving continuous intravenous sedation with propofol.

Interventions: Sedation monitoring using clinical assessment with the Ramsay scale (Ramsay-alone group) or clinical assessment plus BIS monitoring (BIS-augmentation group). Subjects were randomized to Ramsay-alone (n = 35), or BIS-augmentation (n = 32). Nurses adjusted the dose of propofol to a Ramsay of 4, or a Ramsay of 4 and BIS between 60 and 70.

Measurements and main results: Patients in the BIS-augmentation group received significantly less propofol by volume (93.5 ml vs. 157.8 ml, respectively; P < .015), and had lower infusion rates (14.6 vs. 27.9 mcg/kg/min; P = .003). There is a lower risk of propofol infusion exceeding manufacturer's recommended dosing guides in the BIS-augmentation group versus the Ramsay-alone group (0 vs. 23%, P = .0052). The BIS-augmentation group woke up much quicker than those in the Ramsay-alone group (1.2 vs. 7.5 min; P < .0001).

Conclusions: BIS-augmented sedation monitoring resulted in a marked reduction in the total dose of sedative used to achieve the same level of clinical sedation resulting in shortened time to wake up without any measurable adverse effects. Physiologic sedation assessment tools may provide a useful means of improving the care of sedated critically ill patients.

Fig. 1

Distribution of BIS values for subjects randomized to the BIS-augmentation group

Fig. 2

Propofol infusion rates for the Ramsay-alone and BIS-augmentation group. Mean propofol infusion rates (mg/kg/h) are shown for each individual (with minimum and maximum hourly rates represented by vertical bars). Groups are separated by a space for visual clarity