Aim of the study: Determine the use of bispectral index (BIS) as prognostic tool in therapeutic hypothermia (TH) treated comatose survivors after cardiac arrest (CA), regardless of initial rhythm, location or cause.
Methods: Prospective, single-centre, unblinded, observational cohort study in an 18 bed general ICU in a tertiary teaching hospital. 45 consecutive comatose patients admitted after CA and treated with TH were included. All patients were sedated with a standardised protocol including neuromuscular blockade. Induced TH was started as soon as possible after arrival in the hospital and continued for 24h before slow rewarming. Sedation was stopped after reaching normothermia (36 degrees C). All patients benefited from maximal supportive intensive care and no therapeutic withdrawal or withholding was done unless bad neurological status was confirmed. Continuous BIS monitoring was performed over 72h in all patients.
Results: 14 patients presented BIS values of zero (0) during their ICU stay. At 6 months 11 patients were dead, 1 remained comatose and 2 had severe neurological sequelae (CPC3). No patient of this group had good neurological outcome or improved his neurological outcome between ICU and 6-month follow-up. 31 patients had BIS values higher than 0. At 6 months of those, 11 died, none remained comatose, 3 had bad neurological outcome (CPC3) and 17 had no or minor neurological sequelae (CPC1-2). Thus no correlation between good outcome and BIS values higher than 0 is possible.
Conclusions: BIS values of 0 help predict bad neurological outcome after CA and induced hypothermia.