We test the hypothesis that quantitative electroencephalogram (qEEG) can be used to objectively assess functional electrophysiological recovery of brain after
hypothermia in an asphyxial
cardiac arrest rodent model. Twenty-eight rats were randomly subjected to 7-min (n = 14) and 9-min (n = 14)
asphyxia times. One half of each group (n = 7) was randomly subjected to
hypothermia (T = 33 degrees C for 12 h) and the other half (n = 7) to normothermia (T = 37 degrees C). Continuous physiologic monitoring of blood pressure, EEG, and core body temperature monitoring and intermittent arterial blood gas (ABG) analysis was undertaken. Neurological recovery after
resuscitation was monitored using serial Neurological Deficit Score (
NDS) calculation and qEEG analysis. Information Quantity (IQ), a previously validated measure of relative EEG entropy, was employed to monitor electrical recovery. The experiment demonstrated greater recovery of IQ in rats treated with
hypothermia compared to normothermic controls in both injury groups (P < 0.05). The 72-h
NDS of the
hypothermia group was also significantly improved compared to the normothermia group (P < 0.05). IQ values measured at 4 h had a strong correlation with the primary neurological outcome measure, 72-h
NDS score (Pearson correlation 0.746, 2-tailed significance <0.001). IQ is sensitive to the acceleration of neurological recovery as measured
NDS after asphyxial
cardiac arrest known to occur with
induced hypothermia. These results demonstrate the potential utility of qEEG-IQ to track the response to neuroprotective
hypothermia during the early phase of recovery from
cardiac arrest.