Analyses of factors contributing to vulnerability to antenatal periventricular leukomalacia induced by hemorrhagic hypotension in chronically instrumented fetal sheep.

Our purpose was to determine factors contributing to vulnerability to antenatal periventricular leukomalacia (PVL) induced by hemorrhagic hypotension in premature fetal sheep. Systemic hypotension was induced in 10 fetal sheep by acutely withdrawing 35% to 40% of the fetoplacental blood volume at 113 d gestation. Brains were processed for histologic analysis 6 d after the insult. Statistical comparisons of physiologic parameters between fetuses suffering from PVL (n = 5) and those without PVL (n = 5) were performed. Significant correlations were found between induction of PVL and fetal brain weight, changes in fetal mean blood pressure over time, base excess, oxygen content, hematocrit, and plasma arginine vasopressin (AVP) levels in fetal abdominal aortic blood. Brain developmental stage, the magnitude of induced systemic hypotension, and baseline blood oxygen content were important intrinsic factors in the induction of antenatal PVL by hemorrhagic hypotension in premature fetal sheep.