Bispectral Index Monitoring in Helicopter Emergency Medical Services Patients

Abstract

Background. Many critically ill patients are given sedatives andparalytics to facilitate aeromedical transport. Bispectral index (BIS) monitoring is a computer-derived electroencephalography (EEG) analog currently used to monitor the level of awareness of sedated patients. It gives a score of 1–100, with 1 representing no brain function and100 representing a completely alert patient. Objective. To evaluate whether critically ill patients are adequately sedated during aeromedical transport. Methods. This was a prospective, observational study of a convenience sample of critically ill patients transported by helicopter. All intubated patients who received sedatives and/or paralytics to facilitate transport were eligible for enrollment by the attending clinician. Prior to liftoff, a BIS sensor was applied to the patient's forehead. Minimum, maximum, andmean BIS index scores were recorded every minute during transport. Results. Forty-seven patients (57% male) were enrolled, with a median age of 60 years (interquartile range [IQR] 18–81, range 14 to 86 years). The median duration of monitoring was 15.0– minutes (IQR 6.0–26.0, range 2 to 33). The median BIS score was 54.6 (IQR 38.6–67.3, range 28 to 89.5). Only two patients (4.3%, 95% confidence interval [CI] 0.5% to 14.8%) had at least one BIS score greater than 85, the accepted threshold for recall. Conclusion. These results suggest that patients are adequately sedated during air medical transport.

Key words:

• air ambulance
• conscious sedation
• BIS monitor
• sedation in HEMS