Pulmonary Peak Flow Assessment: An Easy Tool for Cardiac Output Estimation in Hemodynamically Stable Neonates

Objectives: Right ventricular output (RVO) assessment can estimate systemic blood flow (SBF) in neonates but requires advanced echocardiography expertise. Pulmonary peak flow (PPF) could be an easier surrogate for RVO. This study is aimed at evaluating the correlation between RVO and PPF in neonates and assessing their intraobserver variability. Methods: In this single-center, longitudinal, observational study, we included term and preterm neonates admitted to our Neonatal Intensive Care Unit between February and July 2022. A neonatologist with experience in functional echocardiography recorded targeted neonatal scans. Recordings were analyzed off-line for echocardiographic measurements. After 12 months, a second analysis of the recordings was performed by the same examiner to avoid recall bias. We compared the two analyses for intraobserver variability assessment. Results: We analyzed a cohort of 33 term and preterm infants. We found a strong positive correlation between RVO and PPF (p < 0.001). RVO showed a mean intra-observer difference of 34.2 mL/kg/min; PPF showed a mean intraobserver difference of 2.2 cm/s. Conclusions: Our findings support the use of PPF as a surrogate for RVO for cardiac output estimation in term and preterm neonates. Because of its simplicity, rapidity, and low intraobserver variability, PPF could be a useful tool for SBF assessment. Future studies should be performed to evaluate the correlation between PPF and other echocardiographic markers of low SBF.