[The value of bispectral index in the unconscious patients with acute brain injury due to different pathogenic factors].

OBJECTIVE

To observe the differences in bispectral index (BIS) in unconscious patients with acute brain injury due to different pathogenic factors, and approach its clinical significance.

METHODS

A retrospective study was conducted. One hundred and twenty-two unconscious patients with acute brain injured admitted to the intensive care unit (ICU) from March 2009 to August 2012 were involved. According to the pathogenic factors, all patients were divided into direct injury group (n=66) and indirect injury group (n=56). Based on BIS value, all patients were divided into the BIS<60 group (n=80) and the BIS≥60 group (n=42). The BIS was continuously measured for 12 hours during the first 3 days, or 24 hours after stoppage of sedative after admission to ICU. The mean value of BIS (BISmean) was evaluated. The acute physiology and chronic health evaluationII (APACHEII) score, probability of survival (PS) and Glasgow coma score (GCS) were recorded. On the same day, the serum protein S100 and neuron-specific enolase (NSE) were determined. The mortality and the rate of the poor neurological outcome were analyzed.

RESULTS

(1) There were no significant differences in the age, sex, APACHEII score, PS and days of stay in ICU between the direct and indirect injury groups. (2) BISmean and GCS in direct injury group were significantly lower than those of the indirect injury group [BISmean: 39.0 (2.5, 58.0) vs. 59.0 (42.0, 71.0), GCS score: 3 (3, 5) vs. 4 (3, 6), both P<0.01], while serum S100 levels was significantly higher [2.30 (0.75, 6.66) mg/L vs. 0.84 (0.40, 3.62) mg/L, P<0.01]. There was no significant difference in the NSE level between the direct and indirect injury groups. (3) The mortality rate and poor neurological outcome rate in BIS<60 group were significantly higher than the BIS≥60 group (mortality rate: 67.50% vs. 40.48%, poor neurological outcome rate: 86.25% vs. 66.67%, P<0.01 and P<0.05). In the BIS<60 group, there were no significant differences in the mortality and poor neurological outcome rate between direct and indirect injury group.

CONCLUSIONS

There are differences in pathogenic factors, the injury mechanism, and the degree of the brain injury between the direct and indirect injury groups. BIS monitoring could help judge the degree of different kinds of brain injury. BIS<60 indicates poor prognosis and neurological outcome in spite of the inducing factor of brain injury.