Antenatal betamethasone improves postnatal transition in late preterm lambs with persistent pulmonary hypertension of the newborn.
BACKGROUND
Persistent pulmonary hypertension of the newborn (PPHN) is associated with increased oxidative stress in pulmonary arteries (PAs). Betamethasone decreases the oxidative stress and improves antioxidant balance in PPHN. We investigated whether antenatal betamethasone improves pulmonary vasodilation and postnatal oxygenation in late preterm lambs with PPHN.


METHODS
PPHN was induced by constriction of fetal ductus arteriosus from 128 to 136 d gestation. Ewes were given two intramuscular doses of betamethasone or saline at 24 and 12 h before cesarean-section delivery at 136 d gestation, simulating late preterm birth. Newborn lambs were mechanically ventilated for 8 h with monitoring of blood gas and hemodynamic variables. Lungs were harvested postmortem to determine oxidative stress markers and in vitro responses of PAs.


RESULTS
Postnatal arterial partial pressure of oxygen and pH were higher and the oxygenation index and arterial partial pressure of carbon dioxide were lower in betamethasone-treated lambs. PA pressure was lower and systemic pressure higher in lambs treated with betamethasone. Betamethasone decreased the oxidative stress markers and increased endothelial nitric oxide synthase expression in ventilated PPHN lungs.


CONCLUSIONS
Antenatal betamethasone decreases oxidative stress and improves postnatal transition in late preterm lambs with PPHN. This study suggests a potential benefit for antenatal betamethasone in late preterm births.
Department of Pediatrics, Children's Research Institute and Cardiovascular Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin, USA. gkonduri@mcw.edu
Girija G
GG
Konduri
Ivane
I
Bakhutashvili
Annie
A
Eis
Adeleye
A
Afolayan
D000818:Animals; D000831:Animals, Newborn; D001623:Betamethasone / Q000627:therapeutic use*; D005938:Glucocorticoids / Q000627:therapeutic use*; D006976:Hypertension, Pulmonary / Q000517:prevention & control*; D012756:Sheep
D005938:Glucocorticoids; D001623:Betamethasone