Prostaglandin E1 selectively reduces group B beta-hemolytic streptococci-induced pulmonary hypertension in newborn piglets.

Group B beta-hemolytic streptococci (GBS)-induced pulmonary hypertension was generated in ten newborn piglets. Intravenous infusions of either prostaglandin E1 (PGE1) (n = 5) or placebo (n = 5) were begun after 60 minutes of stable pulmonary hypertension. The effects of these interventions on cardiopulmonary hemodynamics were studied. Pulmonary artery pressure (PAP) increased similarly in both groups during the first 60 minutes of GBS infusion. By two hours after intervention, PAP was significantly lower in the animals given PGE1 (20 +/- 4 vs 32 +/- 5 mm Hg for PGE1 vs placebo). The ratio of pulmonary to systemic vascular resistance followed a pattern analogous to PAP, increasing with the GBS infusion, indicating selective pulmonary vasoconstriction. The pulmonary vascular resistance/systemic vascular resistance ratio decreased after intervention in the group given PGE1 only (0.25 +/- 0.08 vs 0.50 +/- 0.12 for PGE1 vs placebo), indicating selective pulmonary vasodilation. Transient systemic hypotension was noted at one hour after initiation of PGE1 infusion. Prostaglandin E1 infusion selectively improved GBS-induced pulmonary hypertension and hypoxemia in newborn piglets with only transient systemic hypotension.