Continuous Versus Multiple Rapid Infusions of Indomethacin: Effects on Cerebral Blood Flow Velocity

Objective. Therapeutic administration of indomethacin for patent ductus arteriosus (PDA) closure has been documented to decrease cerebral blood flow velocity which may be harmful to the vulnerable premature neonate. We have therefore compared the effects of administering indomethacin by rapid injection versus slow, continuous indomethacin infusion at the same total therapeutic dose on middle cerebral artery (MCA) systolic and diastolic flow velocity, resistance index, and cerebral blood flow (as reflected by the integrated area under the curve). Methods. Premature neonates (<1750 g) documented echocardiographically to have a PDA were randomized to receive indomethacin either by three rapid injection doses or by continuous intravenous infusion over the ensuing 36 hours, providing an equivalent total dose. Echocardiograms and transcranial color flow mapping of the MCA flow velocity were measured at baseline and serially following initiation of therapy in both groups. Effects on cerebral blood flow velocity are presented. Results. Eighteen infants [rapid injection-1.2 ± 0.3 kg (n = 9) and continuous-1.1 ± 0.2 kg (n = 9)] were studied. In the rapid injection treated infants decreased flow velocity in the MCA as manifested by abrupt, significant decreases in systolic (to 70 ± 8% baseline) and diastolic (to 65 ± 13% baseline) flow velocity and area under the curve (to 60 ± 10% of baseline) were evident by 4 minutes and progressed to 30 minutes after treatment initiation. These changes were not observed in the group treated with continuous indomethacin. Both therapeutic modalities were equally successful in closing the ductus, although the numbers are too small to definitively determine therapeutic efficacy. Conclusions. Slow, continuous infusion eliminated the decrease in cerebral flow velocity and appears to be effective in closing the PDA.