Repeatability of echocardiographic parameters to evaluate the hemodynamic relevance of patent ductus arteriosus in preterm infants: a prospective observational study

BACKGROUND The hemodynamically relevant patent ductus arteriosus in preterm infants is not well defined. Different clinical and echocardiographic parameters are used and the diagnostic accuracy is unknown because of the lack of a gold standard definition. Our study evaluates the inter-observer repeatability of echocardiographic and Doppler-ultrasound parameters. METHODS This prospective observational study included 19 very low birth weight preterm infants (median [interquartile range]: gestational age 28.0 (28.0-29.0) weeks, birth weight 1130 (905-1321) g, postnatal age at measurement 8.7 (4.8-23.5) d) with a clinical suspicion of ductal patency in whom 27 repeated echocardiographic and Doppler-ultrasound examinations were performed within 30 min by 2 of 3 independent observers (54 measurements overall). The repeatability index (=2 times the standard deviation of the differences/mean of all measurements) according to Bland and Altman was used to assess repeatability of different parameters. RESULTS The repeatability indices of the echocardiographic parameters (left Atrium-to-Aortic root-ratio, diameter of the patent ductus arteriosus at its narrowest part, the left-ventricular-preejection-period-to-ejection-time-ratio and the ratio of the velocity time integrals in the large vessels were 16, 21, 23 and 26 % respectively. The repeatability indices of Doppler-ultrasound measurements (resistance index in celiac artery and anterior cerebral artery) were 11 and 14 %, respectively. CONCLUSIONS The inter-observer repeatability of all echocardiographic parameters was poor compared to that of resistance indices in peripheral vessels. Therefore, interventions for ductal patency should be indicated based on averaged repeated rather than single measurements, especially when measured values are close to their cut-off value - both in clinical routine and for study purposes.