Sir.—Sell et al1 recently reported on the neurodevelopmental outcome of infants suspected of having persistent fetal circulation (PFC) in the newborn period. The significant number of infants noted to have a hearing loss is an important finding. The authors' findings, however, may not be applicable to all infants with persistent pulmonary hypertension of the newborn (PPHN) because of a number of apparent flaws in the study.
First, the authors give the impression that all infants with PPHN born during the study period were included in their population. If this is true, how do the authors account for a mortality rate of 0% over seven years? The reported mortality rate for PPHN during the same period was 50% to 78%.2,3 Next, less than half of the study population had PPHN as defined by Fox and Duara.4 The authors define PFC or PPHN in the introduction as hypoxemia