Abstract P82: Bispectral Index Is Useful For Predicting Neurological Outcome In Unconscious Post-Cardiac Arrest Syndome Patients
The prediction of neurological outcome is crucial in unconscious post-cardiac arrest syndrome (PCAS) patients, especially in this era of application of hypothermic therapy as the standard procedure, since especially muscle relaxant administered during the therapy might mask the patients’ neurological responses.
Methods: We examined retrospectively the time course changes in bispectral index value (BIS: an index combining EEG and EMG) and suppression ratio (SR: a ratio of cortical silence in the EEG) within 72 hours after the event using a BIS XP monitor in 20 consecutive unconscious PCAS patients. Statistical analysis was done using Mann-Whitney U-test.
Results: BIS values in patients with good neurological outcome (GR and MD in GOS), when being administered muscle relaxant, were significantly higher than those with poor prognosis (55±15 vs 8±7, mean±sd, p=0.0002). In contrast, SR ratios in subjects with favorable outcome were much lower than those with poor prognosis (33±32 vs 63±46, mean±sd, p=0.009). However, BIS values, even in patients with poor outcome, if not given muscle relaxant, were in the normal range despite deep coma, suggesting the influence of EMG on BIS values.
Conclusion: Bispectral index could be a useful predictor of neurological prognosis in unconscious PCAS patients undergoing hypothermic therapy even in the early phase, but needs to be careful on the evaluation for its values if muscle relaxant is not administered.