Ductal shunting, high pulmonary blood flow, and pulmonary hemorrhage

Objective: To describe the relationship among ductal shunting, estimated pulmonary blood flow, and pulmonary hemorrhage in very preterm infants. Study design: A total of 126 babies born before 30 weeks' gestation (median gestation 27 weeks, range 23 to 29 weeks) underwent echocardiography, at 5, 12, 24, and 48 hours of age; measurements included right and left ventricular output, superior vena cava flow, and color Doppler diameter of any ductal shunt. Pulmonary, blood now was derived from the sum of right ventricular output and estimated ductal shunt flow. Results: Twelve (9.5%) babies had a pulmonary hemorrhage at a mean age of 38 hours. Compared with the rest of the cohort, these 12 babies were less likely to have had antenatal steroids (59% vs 90%) and were less mature (26 weeks vs 27 weeks). At the echocardiogram closest to the pulmonary hemorrhage, 11 (92%) of the 12 babies had a significant patent ductus arteriosus >1.6 mm in diameter (median 2 mm, range 0.7 to 2.4 mm), and the median pulmonary blood flow was 326 mL/kg/min (range 210 to 598 mL/kg/min). These measurements were significantly higher than those found in the rest of the cohort in the same period (med;an duct diameter 0.5 mm [range 0 to 2.9 mm], median pulmonary blood now 237 mL/kg/min [range 107 to 569 mL/kg/min]). At 5-hour echocardiography the babies with pulmonary hemorrhage had significantly larger diameter ducts but similar pulmonary blood flow. Conclusions: Pulmonary hemorrhage in preterm babies is associated with significant ductal shunting and high estimated pulmonary blood flow.