This study was an observational study to estimate the prevalence of Persistent pulmonary hypertension of the newborn (PPHN) among term or near-term infants with severe respiratory disease.

The optimal approach to the treatment of PPHN remains controversial. In 1978, hyperventilation was advocated for the treatment of PPHN. Newer therapies such as alkali infusion have been introduced without the support of randomized trial. In addition, in 1993, large controlled trials of inhaled nitric oxide were in the planning stages. There is a lack of knowledge about how these diverse management styles impact patient outcome.

Given the large number of treatments used in neonates with PPHN, we wished to document treatment of PPHN and outcomes of those treatments. Therefore, we performed a prospective, observational study to document prevalence of PPHN, the treatments and outcomes in a large population of infants treated at the 12 centers of the National Institute of Child Health and Human Development (NICHD) Neonatal Research Network. Further, we sought to compare treatment with hyperventilation to treatment with alkali infusion.

Inclusion Criteria:

• >= 34 weeks gestational age
• On mechanical ventilation and/or fraction of inspired oxygen >0.50; and
• Had documented pulmonary artery hypertension as defined by either two-dimensional echocardiographic evidence of elevated pulmonary pressure (judged by right to left or bidirectional shunt), or a preductal to postductal oxygen gradient >20 mm Hg

Exclusion Criteria:

• >7 days of age

The infants were screened within the first 24 hours and were followed until enrollment criteria were met or until they reached 7 days of age, whichever occurred first.