Abstract

AIM To describe the association between early postnatal prostacyclin concentrations in preterm infants; echocardiographic measurements of ductal diameter and ventricular output and clinical outcomes of intraventricular haemorrhage (IVH) and patent ductus arteriosus (PDA).

METHODS Forty nine preterm infants born before 30 weeks of gestational age (median birthweight 980 g, median gestational age 27 weeks) underwent echocardiographic studies at 5, 12, 24 and 48 hours of postnatal age. Measurements included ventricular outputs and the ductal shunt diameter as a measure of the shunt size. Simultaneous measurements of blood pressures, mean airway pressure and inspired fraction of oxygen (FIO₂) were recorded. A blood sample for the prostacyclin metabolite 6-ketoprostaglandin F1-alpha (6KPGF_1α) was taken at the 5 and 24 hour echocardiogram.

Results—The mean 6KPGF_1α concentrations were higher than adult concentrations at 5 (515 pg/ml) and 24 (255 pg/ml) hours. There was no association with gestational age. Raised 6KPGF_1α concentrations were related to increased need for mechanical ventilation and severity of respiratory disease. At 5 hours, increased 6KPGF_1α concentrations were associated with larger PDA and at 24 hours with larger PDA and higher left ventricular output. Infants with higher 6KPGF_1α concentrations were more likely to develop clinically significant PDA. There was no association between early measurements of 6KPGF_1α and IVH.

CONCLUSIONS Early postnatal prostacyclin concentrations are markedly raised in preterm infants, particularly in those with more severe lung disease. Raised 6KPGF_1αconcentrations were associated with an increased ductal diameter and subsequent PDA, but not IVH.