Early postnatal echocardiographic assessment of pulmonary blood flow in newborns with congenital diaphragmatic hernia

Objective: Echocardiography is the most important tool to assess infants with congenital diaphragmatic hernia (CDH) for pulmonary hypertension (PH). The pattern of blood flow in the pulmonary artery [described as time to peak velocity (TPV)/right ventricular ejection time (RVET) ratio] provides distinct information about pulmonary arterial pressure. The aim of our study was to investigate the correlation of TPV/RVET measurements with the most commonly used classification system for PH in CDH new-borns and the association of these measurements with outcome parameters. Methods: Echocardiographic measurements were obtained in 40 CDH newborns within 6 h of life. The obtained measurements were correlated with the decision for or against extracorporeal membrane oxygenation (ECMO); early mortality; total duration of mechanical ventilation and total duration of oxygen supplementation. Results: The correlation coefficient between severity of PH and TPV/RVET measurements was -0.696 (P < 0.001). Using receiver operating characteristic (ROC) analyses the optimal cutoff for TPV/RVET in order to predict the necessity for ECMO or early mortality without ECMO was 0.29 with a sensitivity of 86.7%, a specificity of 68%, a positive predictive value of 61.9% and a negative predictive value of 89.5%. Newborns with a TPV/RVET below the cutoff had a 5.9-fold risk for ECMO or early mortality, a significantly longer duration of mechanical ventilation (13.4 days vs. 7.4 days, P = 0.003) and oxygen supplementation (22.4 days vs. 9.0 days, P = 0.019), and a lower survival rate (76.2% vs. 100%, P = 0.021). Conclusions: TPV/RVET is a feasible parameter to assess PH in CDH newborns with close correlation to outcome parameters.