EFFECTS OF PROPHYLACTIC LOW-DOSE INDOMETHACIN ON HEMODYNAMICS IN VERY-LOW-BIRTH-WEIGHT INFANTS

Indomethacin decreases cerebral and mesenteric blood flow velocities i n premature infants with symptomatic patent ductus arteriosus. Low-dos e indomethacin is recommended fur the prevention of intraventricular h emorrhage in very low birth weight infants, The hemodynamic effects of prophylactic indomethacin have not been previously examined. We hypot hesized that prophylactic indomethacin does not change cerebral and me senteric blood flow velocities and cardiac Function in very low birth weight infants, Twenty-one infants (775 to 1245 gm, 24 to 31 weeks' ge station) were studied before and after indomethacin (0.1 mg/kg) admini stration at 6, 30, and 54 hours of life. Mean and end-diastolic cerebr al and mesenteric blued flow velocities decreased (ANOVA p < 0.05) aft er prophylactic indomethacin. The 38% increase in cerebral relative va scular resistance was significantly greater than the 18% increase in m esenteric relative vascular resistance (ANOVA, p < 0.05). In five infa nts who were fed 1 hour after the third indomethacin dose, the postpra ndial mesenteric blood flow velocity was significantly greater than th e mesenteric blood flow velocity before both indomethacin and feeding (ANOVA, p < 0.05). Cardiac output, stroke volume, fractional shortenin g, nd blood pressure did not change after prophylactic indomethacin ad ministration. We conclude that prophylactic indomethacin (I) reduces c erebral and mesenteric blood now velocity without affecting cardiac fu nction, (2) increases cerebral more than mesenteric relative vascular resistance, and (3) does not prevent postprandial increases in mesente ric blood flow velocity. We speculate that the increase in cerebral re lative vascular resistance is a beneficial effect that contributes to protection against intraventricular hemorrhage.