Bispectral index as a guide for titration of propofol during procedural sedation among children

Abstract

Objective: To determine whether the bispectral index (BIS) monitor could be used to guide physicians in titrating propofol to an effective safe level of deep sedation for children undergoing painful medical procedures.

Design: Multiphase clinical trial.

Setting: Outpatient treatment center of a university children's hospital.

Patients: Pediatric outpatients undergoing painful medical procedures.

Interventions: Patients were sedated with propofol for the procedures. Patients were monitored with a BIS monitor, and the BIS score was correlated with the patient's clinical level of sedation. The BIS score was then used as a guide to titrate propofol in the last phase of the study.

Measurements and main results: The study consisted of 3 phases. In a chart review of data for 154 children who underwent 212 procedures, propofol was found to be safe and effective, with consistent dosing among the intensivists administering the medication. The children received a mean bolus dose of propofol of 1.56 mg/kg, with a mean total dose of propofol of 0.33 mg/kg per minute for the duration of the procedure. In the second phase, 21 patients ranging in age from 27 weeks to 18 years, with normal neurologic function, were sedated with propofol. An observer who was blinded to the BIS scores recorded clinical levels of sedation and reactivity (with a modified Ramsay scale and reactivity score) every 1 to 3 minutes. Another observer recorded the BIS scores at the same times. A total of 275 data points were collected and evaluated. All data points from the times at which patients were considered to be sedated adequately were used to construct a normal distribution of BIS scores. The mean BIS score was 62. This distribution was used to predict that a maximal BIS score of 47 was needed to ensure adequate sedation for 90% of the population. In the third phase of the study, an algorithm was devised to determine the target BIS score necessary for adequate sedation of 95% of the patients. We chose an initial BIS score of 50 (at which 85% of the patients in phase 2 were sedated) because of the possibility of data from phase 2 being skewed toward oversedation. Propofol was administered by an intensivist in an attempt to maintain the target BIS score. A blinded observer noted the patient's clinical level of sedation. In this group, there were 2 failures, ie, patients were clinically uncomfortable despite a BIS score of < or =50, representing only 90% success. Therefore, with the algorithm, propofol was titrated to sedate the next patients to a BIS score of 45. These patients required a mean bolus dose of 1.47 mg/kg and a mean total dose of 0.51 mg/kg per minute to maintain a BIS score of 45. They awakened in 12.75 minutes. All patients were sedated adequately, all procedures were successful, and no patients experienced complications from the sedation. To eliminate variability in the way propofol was dosed, the next 10 patients were given propofol according to a standardized protocol. These 10 children received an initial bolus of 1 mg/kg, with incremental bolus doses of 0.5 mg/kg per dose (maximum: 20 mg) to achieve and to maintain a BIS score of 45. With this protocol, all patients were sedated adequately and none experienced complications from the sedation. The patients required a mean bolus dose of 2.23 mg/kg and a mean dose of 0.52 mg/kg per minute to maintain a BIS score of 45. The mean time until awakening was 14.9 minutes. Regarding the total dose over time and the time until awakening, there was no statistical significance between this group and the group sedated to a BIS score of 45 without the dosing protocol.

Conclusion: The BIS monitor can be a useful monitoring guide for the titration of propofol by physicians who are competent in airway and hemodynamic management, to achieve deep sedation for children undergoing painful procedures.