RECOVERY OF THE OVINE FETUS FROM SUSTAINED HYPOXIA - EFFECTS ON ENDOCRINE, CARDIOVASCULAR, AND BIOPHYSICAL ACTIVITY

OBJECTIVE: The purpose of this study was (1) to determine the ability of the ovine fetus to recover from a self-limiting asphyxial insult an d (2) to monitor cardiovascular and biophysical activity as potential markers of such an insult or underlying neurologic impairment. STUDY D ESIGN: Nineteen fetal sheep were studied (12 hypoxia and 7 control) at 0.9 of gestation during a 24-hour control period, up to 8 hours of ei ther sustained hypoxemia or room air, and for a 40-hour recovery perio d. Fetal heart rate, blood pressure, electrocortical activity, electro ocular activity, and breathing movements were monitored continuously. Fetal arterial blood was sampled at set times for blood gases, pH, lac tate, and catecholamine levels. RESULT: Induced fetal hypoxemia result ed in a lactic metabolic acidosis that progressively worsened, with de ath occurring in three of the animals during the early recovery period . The remaining animals showed a rapid metabolic and endocrine normali zation of values by 24 hours. Fetal cardiovascular and biophysical mea surements likewise returned to control values during the early recover y period, although three animals had seizure-like activity. CONCLUSION : The near-term ovine fetus surviving a sustained asphyxial insult suf ficient to induce neuropathologic change within the brain demonstrates a normalization of biophysical activity during the early period of re covery, although seizure-like activity may subsequently be evident.