Hemodynamic responses to asphyxia in spontaneously breathing newborn term and premature lamb.

The comparative effects of asphyxia were studied in spontaneously breathing premature and full term newborn lambs. The premature lambs exhibited significantly higher baseline blood flow to several organs. Asphyxia induced similar changes in regional organ blood flow in preterm and term newborn lambs. Regional differences were found in baseline brain blood flow with an increase from cephalad to caudad. Asphyxia resulted in preferential increases in blood flow to the lower brain structures (cerebellum, medulla, midbrain, and spinal cord). Blood flow to most organs returned to baseline 140 min after recovery from asphyxia.