Patent ductus arteriosus (PDA) is frequent in preterm infants and associated with increased mortality and morbidity. Low gestational ages (GA), sepsis and lack of prenatal steroid exposure are previously identified predictors of pharmacological PDA treatment failure.
To identify early factors affecting ductal closure during pharmacological treatment in extremely preterm infants, with special focus on pulmonary circulation.
Newborn infants, born at 22-27 gestational weeks between January 2006 and December 2008 at Uppsala University Children's Hospital and pharmacologically treated for PDA, were retrospectively identified (Figure 1). Medical charts were assessed for the first day of life, for the days of echocardiographic examination and for the days of treatment. Perinatal factors, vital parameters, ventilatory settings, treatments, fluid intake, complications and outcomes were registered and pre-treatment echocardiography was reviewed. Follow-up echocardiography defined successful or failed ductal closure.
Thirty-two infants were identified (Figure 1). Prophylactic treatment was initiated 3 days after birth (range 1-8) in both groups (P=0.952) with one single course of 3-5 doses indomethacin (n=28) or ibuprofen (n=3).
Infants who failed closure had lower GA (23+6 weeks vs. 25+6 weeks, P=0.048), higher median heart rate during first day of life (155 bpm vs. 145 bpm, P=0.027), were on ventilator
20%, P=0.004), and required longer total time of ventilatory support during hospital stay (28 days vs. 4 days, P=0.013). Other perinatal factors, vital parameters, treatments and fluid intake and incidences of BPD, IVH, NEC and ROP were similar between groups.
Pre-treatment echocardiography revealed lower left to right ductal peak flow velocity in infants that failed closure (P=0.009, Figure 2). When adjusted for ductal diameter, low peak flow velocity was still associated with pharmacological treatment failure (P=0.017), indicating that higher pulmonary arterial pressure might oppose ductal constriction after birth (Figure 3).
Low ductal peak flow velocity is an early predictor of pharmacological PDA treatment failure in extremely preterm infants, possibly reflecting the influence of pulmonary arterial pressure on ductus constriction.
Pediatric Academic Societies annual meeting (PAS), 1-4 maj, Vancouver, Kanada