Prenatal prediction of lethal pulmonary hypoplasia: the hyperoxygenation test for pulmonary artery reactivity

The purpose of this study was to determine the predictive accuracy of a test for neonatal death from pulmonary hypoplasia by measuring changes in fetal pulmonary artery blood flow on room air and during maternal hyperoxygenation.

Women who were carrying fetuses with congenital anomalies that may cause pulmonary hypoplasia were offered participation in the study as part of a comprehensive fetal echocardiogram. Each fetus at > or =30 weeks of gestation underwent Doppler measurement of the blood flow pattern in the first branch of either the right or the left pulmonary artery before and again during exposure to maternal breathing of 60% oxygen by mask. An increase in the fetal pulmonary blood flow with oxygen (a decrease of > or =20% of the pulsatility index) was considered a reactive test. A change of <20% in the flow pattern during maternal hyperoxygenation was a nonreactive test and suggested pulmonary hypoplasia. The primary outcome for this study was neonatal death from pulmonary hypoplasia.

Twenty-nine pregnancies met the criteria for inclusion in our study. Of the 14 fetuses who had a nonreactive hyperoxygenation test, 11 fetuses (79%) died of pulmonary hypoplasia. Of the 15 fetuses who had a reactive hyperoxygenation test, only one fetus (7%) died in the neonatal period. Sensitivity, specificity, and positive and negative predictive values were 92%, 82%, 79%, and 93%, respectively, with an odds ratio of 51 (95% CI, 4.6-560).

Testing fetal pulmonary vascular reactivity with maternal hyperoxygenation is highly predictive of pulmonary hypoplasia. A reactive test predicted 92% of surviving infants; a nonreactive test predicted 79% of fetal deaths from pulmonary hypoplasia.