Effects of Intermittent Nebulization of NONOate, DPTA/NO, on Group B <i>Streptococcus</i>-Induced Pulmonary Hypertension in Newborn Piglets

<i>Background: </i>A single dose of NONOate attenuates pulmonary hypertension (PH) induced by group B <i>Streptococcus</i> (GBS) infusion and this is accompanied by a decrease in systemic vascular resistance (SVR). <i>Objective: </i>The objective of the study was to determine whether two doses of the NONOate sustain the attenuation in GBS-induced PH without further systemic compromise. <i>Methods: </i>15 anesthetized newborn piglets were randomized to receive placebo (n = 8) or two doses of nebulized DPTA/NO (n = 7) at 15 and 75 min after GBS-induced PH. Pulmonary artery (Ppa) and systemic (Psa) pressures, cardiac output (CO) and arterial blood gases were obtained at baseline and every 15 min until 180 min during GBS infusion. <i>Results: </i>Ppa and pulmonary vascular resistance (PVR) decreased significantly after the first dose of nebulized DPTA/NO and this effect was maintained after the second dose. Psa and SVR decreased after the first dose of DPTA/NO to values close to baseline and no further changes in systemic circulation were observed with repeated treatment. PVR/SVR increased with GBS infusion, but decreased after the first dose of DPTA/NO and remained significantly lower for 180 min. CO was significantly higher in the DPTA/NO group. Changes in Ppa, PVR, Psa, SVR, and CO with GBS infusion were not modified by placebo infusion. PaCO₂, base deficit, and pH did not differ between groups. PaO₂ was significantly lower in the DPTA/NO group after the second dose. <i>Conclusion:</i> These data demonstrated that GBS-induced PH is attenuated with two doses of DPTA/NO without significant systemic effect. The vasodilatory effect is more pronounced in the pulmonary than in the systemic vasculature, as suggested by lower PVR/SVR in the DPTA/NO group. We speculate that NONOates may have a clinical application in the management of PH in neonates.