Clinical and electrophysiologic associations with outcome in initially comatose survivors of cardiac arrest

Background

Prognostic assessment of the comatose survivor of cardiac arrest with intact brain stem reflexes is still problematic and requires further study to determine those factors correlate with an outcome no better than vegetative state (VS).

Methods

Inclusion criteria

Comatose survivors of cardiac arrest with GCS ≤ 8 on day 1 before sedation; first EEG and SSEP between 24 and 36 hours from cardiac arrest; survival for at least 4 days.

Exclusion criteria

Patients with brain death, sedation immediately after resuscitation, additional cause for coma, preceding peripheral neuropathy or cervical myelopathy. Standardized EEG classification system and SSEPs were applied. Followup at 3 months with phone call to determine the Glasgow Outcome Scale score (GOS) and whether or not awareness had been recovered.

Results

Forty-six men and 29 women with mean age of 74 (range 21–84) years. Fifty-seven (76%) of the arrests were out-of-hospital and were due to primary cardiac causes in 70 (93%). Significant differences in clinical features between those who died and those who survived were oculovestibular and pharyngeal reflexes (no survivors in those who lost these) and motor response. There were no survivors with better than VS in those with generalized epileptiform discharges or suppression of < 20 μV on EEG and absent N20 on SSEPs. EEG and EP responses correlating with recovery of awareness included those with intermittent EEG slowing and those with preserved N70 responses.

Conclusions

In this preliminary study, the only variables that were consistently associated with an outcome no better than VS were: absence of oculovestibular and pharyngeal reflexes, generalized epileptiform discharges or suppression of < 20 μV on EEG and absent N20 on SSEPs.