Effect of early targeted indomethacin on the ductus arteriosus and blood flow to the upper body and brain in the preterm infant

Abstract

Objective: To determine if indomethacin given to preterm infants with a large ductus arteriosus (DA) in the first hours of life results in maintained or improved brain and upper body blood (superior vena cava (SVC)) flow.

Study design: A randomised, double blind trial of indomethacin v placebo. Echocardiography was performed on 111 infants born at < 30 weeks gestation at 3 and/or 10 hours after birth. Infants were eligible if the DA diameter was > 1.6 mm. Infants were randomised to receive indomethacin 0.2 mg/kg or placebo. Crossover occurred if the DA was still > 1.6 mm. Echocardiography was performed one hour after each treatment.

Results: Seventy (63%) infants had a DA > 1.6 mm, with 35 randomised to receive indomethacin and 35 to receive placebo. At one hour there was no difference in DA constriction (indomethacin -20% v placebo -15%), change in SVC flow (-1% v -9%), for right ventricular output (RVO). Two hours after indomethacin, 62 infants had uncontrolled observations, at which time significant ductal constriction had occurred. At this time, infants of > or = 27 weeks gestation had significantly greater increases in SVC flow and RVO than infants of < 27 weeks gestation. Infants with failed ductal constriction had significantly lower initial SVC flow and developed more late grade 3/4 peri/intraventricular haemorrhage (P/IVH). Initial SVC flow, but not ductal constriction, was a significant predictor of late grade 3/4 P/IVH in adjusted analysis.

Conclusions: Indomethacin had minimal effect on ductal constriction and blood flow at one hour compared with placebo. Failure of ductal constriction is associated with low SVC flow and subsequent late severe P/IVH.

Figure 1

Scatterplots of blood flow in the superior vena cava (SVC) from before to one hour after infusion of placebo (A) or indomethacin (B). n = 35 in each case.