In Reply.—Dr Horgan has made several important observations regarding our report. We did not address mortality rate in our study nor did we intend to suggest that it was 0%; that information was neither available nor retrievable retrospectively.
It is now possible to define PFC (PPHN) with greater accuracy than was available to us, particularly during the early study period. As Dr Horgan notes, Fox and Duara1 suggested one or more of the following as diagnostic tests for PPHN, although it is not clear which one(s) is(are) considered diagnostic: (1) hyperoxia test (term infants only); (2) preductal and postductal arterial oxygen levels; (3) hyperoxia-hyperventilation test; and (4) echocardiographic evaluation of systolic time interval ratios and/or myocardial function. In our study the diagnosis was made by the attending neonatologist from a combination of clinical factors as well as echocardiographic findings in some patients.
The four patients who received oxygen