Systemic levels following PGE1 inhalation in neonatal hypoxemic respiratory failure

Aim: To measure plasma prostaglandin E-1 ( PGE(1)) levels in newborns with hypoxemic respiratory failure ( NHRF) following inhaled PGE1 ( IPGE(1)), normal term newborns, and newborns with congenital heart disease ( CHD) following intravenous PGE(1). Methods: Twenty newborns with NHRF received IPGE(1) by jet nebulizer in doses of 25, 50, 150, and 300 ng/kg/min followed by weaning. Blood for PGE(1) assay using enzyme immunoassay was available in eight neonates with NHRF, 10 normal newborns, and three neonates with CHD. Results: There were no differences in PGE(1) levels between cord arterial blood in normal newborns and baseline samples from newborns with NHRF. Oxygenation improved significantly following IPGE(1) ( p = 0.024) in newborns with NHRF. No adverse events were identified. Although a reversible increase in PGE(1) levels was detected following a dose of 50 ng/kg/min ( p < 0.05), there was no association between PGE(1) levels and IPGE(1) duration, PaO2, temperature, heart rate, and blood pressure. Conclusion: A reversible increase in mean PGE(1) levels was demonstrable at low doses of IPGE(1) in babies with NHRF using a sensitive assay, suggesting effective drug delivery. Levels did not increase further with increasing dose or duration of administration, suggesting local action in the lungs and a lack of systemic spillover due to extensive pulmonary metabolism offering pulmonary selectivity.