The association of a decreased level of awareness and blood alcohol concentration with both agitation and sedation in intoxicated patients in the ED☆

Abstract 

Objective

This study was conducted to compare the level of awareness as determined by serial bispectral index (BIS) electroencephalogram scores to a standardized Altered Mental Status (AMS) scale used to define a patient's clinical level of agitation or sedation, and the patient's concurrent breath/blood alcohol concentration (BAC).

Methods

This was an institutional review board-approved, prospective observational study of a convenience sample of patients who presented to the emergency department (ED) with the chief complaint of ethanol (ETOH) intoxication between July 19, 2003, and March 27, 2004. The AMS scale is a 9-point scale: −4 is unresponsive, 0 is normal examination, and +4 is extremely agitated. After ETOH was detected by breath analyzer, enrolled patients had a BIS monitor probe applied to their forehead. Baseline BAC, BIS, and AMS scores were recorded independently of the patients' caregivers. Bispectral index and AMS scores were repeated every 20 minutes for 1 hour. The patient's diagnosis, disposition, (any) complications, and total time in department were recorded.

Results

Ninety-eight patients were enrolled in the study. The median presenting AMS score was −1. The mean total time in department was 402.6 minutes (SD, 196.4; range, 246-906 minutes). The mean presenting BIS score was 77.6 (SD, 17.9; range, 26-98). The mean presenting BAC was 0.229 (SD, 0.07; range, 0.049-0.43). The mean BIS index varied from 59.6 ± 16.9 for AMS scores of −4, to 96.3 ± 2.7 for AMS scores of 0, to 90.5 ± 4.9 for AMS scores of 4. The AMS scale correlated with the BIS scale (Spearman's ρ = 0.67, P ≤ .001), but did not correlate with BAC (Spearman's ρ = −0.14, P = 0.15).

Conclusions

Changes in the AMS scale corresponded to changes in the BIS index score. A decreased level of awareness, as determined on the BIS index, was observed in patients who were either agitated or sedated by the AMS. We conclude that both agitated and sedated patients with ETOH intoxication show decreases in their level of awareness. Therefore, the AMS scale, which includes both agitation and sedation, is a valid measure of a patient's decreased level of awareness.