Systemic levels following PGE 1 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 PGE 1 (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, P a O 2 , 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.