Serial assessment of ductus arteriosus hemodynamics in hyaline membrane disease

To assess the efficacy of Doppler echocardiography (DE) in the quantification of patent ductus arteriosus (PDA) shunt volume and to correlate PDA shunt volume with clinical outcome in infants with hyaline membrane disease. Ninety-eight DE studies were performed in 30 preterm ventilated infants with hyaline membrane disease within the first 24 hours of age and then at 48-hour intervals to a maximum of three studies while ventilated with a final study after extubation. Right and left ventricular outputs (QRV and QLV, respectively) and PDA flow were calculated using cross-sectional area and flow velocity integrals. Left atrial-to-aortic root diameter measurements were also taken. Clinical outcomes were correlated with the shunt fraction (QLV/QRV). QLV/QRV demonstrated a linear relationship with the left atrial-to-aortic root diameter ratio (n = 92; r = .79). In the absence of a PDA (n = 33 studies), QRV versus QLV demonstrated a linear relationship (r = .88). In the presence of a PDA (n = 64 studies) the mean QLV (334 +/- 133 ml/kg per minute) was significantly greater than the mean QRV (237 +/- 84 ml/kg per minute). There was a linear relationship between QLV-QRV (PDA shunt volume) and PDA flow (n = 60; r = .84). In studies with exclusive left-to-right shunting at the PDA (n = 48), the mean QLV-QRV (112 +/- 83 ml/kg per minute) was significantly higher than in those with bidirectional shunting (n = 16; mean QLV-QRV = 50 +/- 27 ml/kg per minute). Two infants with severe intraventricular hemorrhage (IVH grade 3) and two infants with periventricular leukomalacia (PVL) had significantly higher QLV/QRV (2.09 +/- 0.36 and 1.67 +/- 0.02 respectively) than those with no IVH (n = 6; QLV/QRV = 1.31 +/- 0.18) or those with IVH grades 1 and 2 (n = 8; QLV/QRV = 1.48 +/- 0.27). There was no difference in QLV/QRV in infants with or without bronchopulmonary dysplasia and retinopathy of prematurity. Necrotizing enterocolitis did not develop in any of the 30 infants. PDA shunt volume can be quantified by DE. Larger studies are needed to correlate clinical outcome with QLV/QRV.