113 CARDIOVASCULAR ADJUSTMENTS DURING RECOVERY FROM CHRONIC NEONATAL ASPHYXIA IN PIGLETS

Abstract

Prolonged, repeated episodes of asphyxia were induced in newborn piglets to, determine cardiovascular adjustments in the post-asphyxial period. Ten piglets (<24 hours age) had catheters placed in the right, and left ventricles and the descending aorta under general anesthesia. Animals were subjected to 8 episodes of asphyxia by rebreathing into a bag to last gasp over a 2 hour period. Immediately after the last episode, the pH and base deficit were 7.01±.12 and -20±3. The insult induced prolonged seixures and persistent changes in activity in 9 of 10 animals and organ hemorrhage in 4. .Organ blood flow was measured prior to asphyxiation and 1 hour after recovery by radioactive microsphere; injection. Arterial blood gases prior to and 1 hour post-asphyxia were respectively pH-7, 44±.08, pCO2-42±5 Torr. pO2-61±10 Torr, B.D.-2±1; pH-7.20±.21, pCO2-32±12 Torr, PO2-75±19 Torr, B.D.-l4±3. Blood flow one hour post-asphyxia increased significantly to the heart, adrenal and liver and decreased significantly to the small bowel, large bowel, kidney, spleen and skin. Blood flow to the brain decreased from 86±13 cc/100 gm to 45±5 cc/100 gm (p<.0) and was no longer related to paCO2. In spite of normal heart rate, hemodynamic pressures, arterial oxygenation, and ventilation at one hour post-asphyxia, there are major changes in organ perfusion, and the distribution of cardiac output, and autoregulation of brain blood flow.