We developed a model of hypoxic/asphyxic cardiac arrest in piglets to study mechanisms and outcome.We tested the hypothesis that neurologic injury can be predicted by physiologic and electroencephalographic (EEG) abnormalities during and immediately after the hypoxic/asphyxic insult 1-wk old piglets(N=22)were subjected sequentially to 30 min hypoxia (10%FiO2), 5 min roomair, 7 min asphyxia. Standard CPR was performed until restoration of spontaneous circulation (ROSC, MAP>60mmHg). Animals were survived 24-96 hr for neuropathologic and neurologic outcome measures using a novel Neurologic Deficit Score (NDS) on a 0(best) to 150(worst) scale. Animals were assigned to good vs. poor outcome groups based on consciousness and behavior subscores at 24 hrs. EEG was recorded from awake baseline through 4 hrs ROSC. Quantitative EEG spectral analysis yielded an index of disproportional power recovery of dominant frequencies compared to the awake baseline (mean normalized separtion[MNS]). We observed that failure to acheive ROSC in 6/22 animals was associated with a lower PaO2 during hypoxia, and earlier circulatory arrest during asphyxia. In successfully resuscitated animals, high degrees of disproportional EEG frequency recovery (high MNS) during the first 4 hrs of recovery correlated with high 24-hr NDS. MNS at 45-220 min post-ROSC distinguished good vs. poor outcome groups at 24 hr recovery. High 24-hr NDS also correlated with low pH at the end of hypoxia, low pH at 15 min ROSC and low arterial glucose at 15 min ROSC. High 24-hr NDS was associated with seizures thereafter, and greater neocortical neuropathology at 96 hr. All non-surviving animals (4/10) died in status epilepticus and exhibited cerebral edema. We conclude this model closely resembles human neonatal hypoxic-ischemic injury. NDS provides a novel useful tool to distinguish moderate-to-severe levels of neurologic injury in piglets, and correlates with results of quantitative EEG analysis during early recovery. Success of CPR is related to circulatory status and oxygenation during hypoxia and asphyxia. Neurologic status in survivors at 24 hrs is related to metabolic status at the end of hypoxia and early recovery. Supported by NS20020, NS01805, McDonnell-Pew Progr. Cogn. Neurosci.