INFLUENCE OF AGE ON CEREBRAL RECOVERY AFTER DEEP HYPOTHERMIC CIRCULATORY ARREST IN PIGLETS

Background. In the first weeks of life there are important maturationa l changes in the central nervous system in many species in energy meta bolism, synapse number, and concentration of neuronal excitatory recep tors. Methods. Four groups of 10 piglets (aged 1, 2, 4, and 10 weeks) underwent 1 hour of deep hypothermic circulatory arrest at 15 degrees C, with cooling and rewarming on cardiopulmonary bypass. Cerebral bloo d flow and metabolic rate measurements and electroencephalographic rec ordings were obtained from 5 animals per group. The remaining animals underwent cerebral magnetic resonance spectroscopy. Results. Preoperat ive cerebral blood flow and glucose consumption were higher at 4 and 1 0 weeks than at 1 and 2 weeks. Cerebral adenosine triphosphate content decreased more rapidly during deep hypothermic circulatory arrest at 4 and 10 weeks. Phosphocreatine recovery was greater at 30 minutes of reperfusion at 10 weeks compared with 1 week. Recovery of cerebral pho sphocreatine/adenosine triphosphate ratio and intracellular pH was rem arkably uniform at all ages. Latency to recovery of electroencephalogr aphic activity decreased with increasing age (p = 0.04). Conclusions. Differences in acute recovery of brain energy metabolism and electroen cephalogram after cardiopulmonary bypass and 1 hour of deep hypothermi c circulatory arrest in piglets between 1 and 10 weeks of age are smal l. Further studies are required to correlate these acute findings with subsequent neurologic outcome.