Control of elevated pulmonary vascular resistance in neonatal swine with prostacyclin (PGI2).

Abstract Three groups of neonatal piglets were anesthetised and baseline hemodynamic measurements were made.The piglets were then subjected to hypoxia and hypercapnea to raise pulmonary vascular resistance (PVR) and further hemodynamic measurements were made over a period of at least 100 minutes. During the last 80 minutes of this period the control group received an infusion of 0.05M Tris buffer [the vehicle for prostacyclin (PGI 2 ], the second group received an infusion of 0.5μg/kg/min PGI 2 , and the third group received an infusion of l.0μg/kg/min PGI 2 . Hypoxia and hypercapnia raised PVR an average of 55%, pulmonary arterial pressure 36% and pulmonary blood flow 41%; because of a trend towards lowered systemic vascular resistance (SVR) the rise in systemic arterial pressure was only 18%. The control group remained relatively stable throughout the 80-minute “treatment” period although there was a slight fall in arterial pressure from 60 minutes. The behaviour of the group receiving 0.5μg/kg/min PGI2 was similar, the only differences being slightly higher pulmonary arterial pressure and slightly lower arterial pressure in the treated group at 80 minutes.By contrast, PVR dropped promptly to baseline levels in the group receiving l.0μg/kg/min PGI2. Systemic resistance also fell but, because of a trend toward raised systemic blood flow, systemic arterial pressure did not fall below baseline levels. PGI2 could be useful in controlling elevated PVR in the neonate.