Cerebral hemodynamics during the induction of antenatal periventricular leukomalacia by hemorrhagic hypotension in chronically instrumented fetal sheep.

Abstract

Our purpose was to determine the characteristics of cerebral ischemia during the induction of antenatal periventricular leukomalacia by hemorrhagic hypotension in premature fetal sheep. The hemorrhage group received an acute withdrawal of 40% of the fetoplacental blood volume (n = 7), whereas an isovolemic exchange transfusion was performed in the control group (n = 7). Changes in the total hemoglobin, oxy-hemoglobin, and deoxy-hemoglobin levels in the cerebral tissue were assessed with the use of near-infrared spectroscopy and compared statistically. Of 7 fetuses in the hemorrhage group, 5 exhibited periventricular leukomalacia but none in the control group (P < .05). In the hemorrhage group, both brain total-hemoglobin and deoxy-hemoglobin decreased seriously after insult, and the decreased levels persisted even after recovery of systemic blood pressure, whereas such drastic changes were not observed in the control group, suggesting the occurrence of reperfusion failure in the fetal brain in the hemorrhage group. The no-reflow phenomenon and successive reperfusion injuries after cerebral ischemia could be closely involved in the induction of antenatal periventricular leukomalacia in this experimental condition.