OBJECTIVE: We sought to analyze the effect of patent ductus arteriosus diameter on treatment success in premature neonates.
METHODS: Among 537 consecutive neonates born between 1985 and 2005 with a diagnosed patent ductus arteriosus, 201 premature patients (<35 weeks' gestation) treated for a hemodynamically significant patent ductus arteriosus were retrospectively reviewed. Two groups were compared: group MED (n = 154; successful treatment with indomethacin) and group FAIL (n = 47; failure of medication to reduce the patent ductus arteriosus diameter to hemodynamic insignificance).
RESULTS: After unsuccessful medical treatment, 33 patients required surgical patent ductus arteriosus closure, 12 died before further possible treatment, and 2 were discharged home without clinical symptoms but with an open patent ductus arteriosus. Mean patent ductus arteriosus diameter in the FAIL group (2.8 +/- 0.9 mm) was significantly larger than that in the MED group (2.4 +/- 0.6 mm, P < .01). Assisted respiration time (ventilation plus continuous positive airway pressure) before patent ductus arteriosus closure was longer in the FAIL group (20 days) than in the MED group (9 days, P < .001) but was similar after patent ductus arteriosus closure. By using an index of patent ductus arteriosus diameter squared/birth weight (in square millimeters per kilogram), a cutoff value of less than 9 mm2/kg correctly predicts medical patent ductus arteriosus closure in 87.5% of patients. Values of greater than 9 mm2/kg correctly predict medication failure in 41.5% of patients.
CONCLUSIONS: In preterm babies requiring surgical patent ductus arteriosus closure, longer respiration times reflect a delay while attempting medical treatment, but respiration time is equally short between groups after shunt elimination. Medical treatment, although a valid first option, is likely to fail with larger patent ductus arteriosus diameters and lower birth weights. Unwarranted assisted respiration and corresponding hospital stay might be shortened by earlier surgical referral for patent ductus arteriosus closure in preterm babies with a patent ductus arteriosus index of greater than 9 mm2/kg.