Background: Superior vena cava (SVC) flow has become a surrogate measure of systemic blood flow in neonates.
Objective: The aim of this study was to establish normal SVC flow values in healthy term infants the first 3 days of life and to evaluate the feasibility and reliability of the off-line analyses.
Design: Doppler echocardiography of SVC flow was performed in 48 healthy term infants the first 3 days of life. Off-line analyses were thereafter performed by one cardiologist to investigate the changes in SVC flow from day 1 to day 3 and to establish normal values. Intra- and inter-observer variability was analysed in a subset of 20 infants by three paediatric cardiologists.
Results: The authors found a decrease in mean SVC flow from 99 ml/kg/min at day 1 to 77 ml/kg/min at day 3. Reliable diameter images were obtained in 85% and velocity recordings in 81%. The mean variability of SVC flow was 17% in the intra-observer analysis and 29% in the inter-observer analysis.
Conclusion: The main challenge of the method is the measurement of SVC diameter. The same observer should ideally perform sequential analyses. Special caution should be taken when making clinical implications from non-optimal pictures.