No abstract

Objective: To investigate the effect of postnatal age at patent ductus arteriosus (PDA) ligation on postoperative need for cardiotropic support.Study Design: A significant proportion of premature infants with a hemodynamically significant ductus arteriosus (HSDA) require surgical intervention. The relationship of postnatal maturation to postoperative cardiorespiratory stability is poorly understood. All preterm neonates who underwent PDA ligation between October 2002 and September 2004 were identified and divided according to postnatal age at ductal ligation, into early (p4 weeks, n ¼ 29) and late (>4 weeks, n ¼ 36) groups. Neonatal birth demographics and morbidities, characteristics of the HSDA and reason for ligation were reviewed. Indices of cardiorespiratory stability (for example heart rate, mean arterial pressure) were recorded before and 1, 4, 8, 12 and 24 h following ligation. Details of perioperative cardiovascular interventions (for example crystalloid boluses, cardiotropic agents) were recorded.Result: There were no differences in baseline neonatal demographics between the groups although a greater number of babies requiring early ligation had contraindication to indomethacin as the main reason for ligation. Early PDA ligation was associated with increased postoperative cardiotrope requirement (27.6 vs 5.6%, P ¼ 0.02) and decreased systolic blood pressure 8 h after intervention (P<0.05). Although increased oxygenation index was observed in both groups during the first 12 h it was only sustained to 24 h in the early group (P<0.05). Age at ligation remained a significant risk factor for postoperative cardiotrope requirement on multiple logistic regression analysis.Conclusion: Surgical ligation of the ductus arteriosus in preterm infants less than 28 days old is associated with oxygenation difficulties, decreased systolic arterial pressure and an increased need for cardiotropic support in the initial 24 postoperative hours. These data suggest the need to prospectively characterize perioperative cardiovascular physiology and identify predictive factors of clinical deterioration.

Patent ductus arteriosus ligation is sometimes associated with impaired left ventricular systolic performance, which is most likely attributable to altered loading conditions. Neonates weighing 1000 g or less are at increased risk of impaired left ventricular systolic performance, which might relate to maturational differences and decreased tolerance to altered loading conditions.

Unadjusted analyses revealed reduction in mortality (unadjusted odds ratio (UAOR): 0.83, 95% confidence interval (CI): 0.63, 0.98), severe retinopathy (UAOR: 0.68, 95% CI: 0.50 to 0.92), but increase in bronchopulmonary dysplasia (UAOR: 1.61, 95% CI: 1.39 to 1.86) and patent ductus arteriosus (UAOR: 1.22, 95% CI: 1.07 to 1.39). Adjusted analyses revealed increases in the later cohort for bronchopulmonary dysplasia (adjusted odds ratio (AOR): 1.88, 95% CI: 1.60 to 2.20) and severe neurological injury (AOR: 1.49, 95% CI: 1.22 to 1.80). However, the ascertainment methods for neurological findings and ductus arteriosus differed between the two time periods.Conclusion: Improvements in prenatal care has resulted in improvement in the quality of care, as reflected by reduced severity of illness and mortality. However, after adjustment of prenatal factors, no improvement in any of the outcomes was observed and on the contrary bronchopulmonary dysplasia increased. There is need for identification and application of postnatal strategies to improve outcomes of extreme preterm infants.

The pharmacokinetics of milrinone in persistent pulmonary hypertension of the newborn is consistent with published data. The administration of intravenous milrinone led to better oxygenation and improvements in pulmonary and systemic hemodynamics in patients with suboptimal response to inhaled nitric oxide. These data support the need for a randomized controlled trial in neonates.