Postoperative cardiorespiratory instability following ligation of the preterm ductus arteriosus is related to early need for intervention.

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 (4 weeks, n=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=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.