Background Central blood flow measurements can provide detailed information on the hemodynamic condition of the preterm infant. However, reference values for right and left ventricular output (RVO and LVO) and superior vena cava flow (SVC flow) are only available for infants in the transitional period. The aim of this study was to determine RVO, LVO and SVC after the transitional period in stable preterm infants.

Methods RVO, LVO and SVC flow were measured with functional echocardiography on days 7 and 14 of life in stable preterm infants less than 32 weeks gestation, with minimal respiratory support and no cardiovascular support. Infants with a clinical suspicion of an infection within 48 h after data collection or a ductal diameter >1.4 mm were excluded from analysis.

Results We performed 111 measurements in 62 preterm infants with a median (range) gestational age of 28 (25–31) weeks and birth weight of 1105 (650–2370) g. 57 measurements were analysed on day 7 and 47 on day 14. The mean (SD) RVO, LVO and SVC flow were 429 (116), 296 (74) and 89 (33) ml/kg/min on day 7 and 433 (81), 300 (79) and 86 (26) ml/kg/min on day 14. There were no significant differences in flows between days 7 and 14 in the paired measurements.

Conclusion This study provides central blood flow values in stable preterm infants after the transitional period. The flow variables were shown to remain stable between days 7 and 14.