Is bispectral index (BIS) monitoring in the emergency department helpful for prognostication during resuscitation of cardiac arrest patients

Objective: It has been suggested that bispectral index (BIS) can be indicative of cerebral perfusion during advanced cardiac life support (ACLS) resuscitation of cardiac arrest patients. Our aim was to determine whether BIS monitoring during resuscitation in the emergency department (ED) can predict survival or neurological outcomes of patients with cardiac arrest. Methods: This was a prospective, single-centre, observational cohort study in the ED of a tertiary hospital, where we included 100 patients whom received resuscitation in the ED between December 2010 and March 2014. We recorded BIS values, suppression ratio, electromyography and signal quality index; throughout the resuscitation. A research coordinator set up the monitoring apparatus at the earliest time possible. Results: Out of the 100 patients recruited, 22 had a sustained return of spontaneous circulation (ROSC) and were admitted to the intensive care unit (ICU). Of these, 19 patients subsequently died in the ICU, two were discharged with good neurological recovery (cerebral performance category (CPC) 1) and one was discharged with poor neurological recovery (CPC4). By comparing the groups of patients who died in the ICU and were discharged, we found there was no significant difference in the initial BIS score (p = 0.64), the score upon ROSC (p = 0.36), the average BIS score 10 minutes post-ROSC (p = 0.35), nor the BIS score upon admission to the ICU (p = 0.22). Conclusions: Very early monitoring of BIS before admission to the ICU predicts neither survival nor neurological recovery in patients with cardiac arrest. Very low BIS scores in the ED may not indicate a poor prognosis, especially in patients undergoing therapeutic hypothermia.