Continuous indomethacin infusion may be less effective than bolus infusions for ductal closure in very low birth weight infants.

The effectiveness of continuous indomethacin (INDO) infusion versus bolus infusions for closure of patent ductus arteriosus (PDA) was investigated. The study design was an open-label case series (continuous INDO) with historic controls matched for gestational age (bolus INDO). Ductal closure rates were determined in two groups: 16 preterm infants with PDA treated with continuous INDO infusion (CONTIN group) and 16 control patients, matched for gestational age, who received bolus INDO infusions (BOLUS group). The total dosage was the same for both groups. PDA closed in seven of 16 preterm infants in the CONTIN group and in 13 of 16 in the BOLUS group ( p = 0.033, Fisher's exact test). In infants < 1000 g it was two of eight in the CONTIN group and 10 of 10 in the BOLUS group ( p = 0.002). Continuous INDO infusion was more likely than bolus infusion to be associated with failure of ductal closure (odds ratio, 19; 95% CI, 1.5 to 247; p = 0.023). This indicates that continuous infusion of INDO may be less effective in closing PDA than bolus infusions, especially in extremely low birth weight infants.