Serial measurements of neonatal cardiac output following caesarean section using Doppler ultrasound - establishing reference ranges
Abstract Number: 57
Abstract Type: Original Research
Introduction: Non-invasive cardiac output monitoring has never been calibrated for use in neonates despite extensive use in both adult and paediatric practice. The USCOM (Ultrasonic Cardiac Output Monitor) incorporates anthropometrics to estimate valve areas in neonates to allow monitoring of left ventricular output at the Aortic Valve (AV) and right ventricular output at the Pulmonary Valve (PV). The aim of this study was to establish normal reference ranges for cardiac output in the healthy, term neonate using the USCOM.
Methods: After ethical approval, 40 term neonates delivered by elective caesarean section, following an uncomplicated antenatal course, were recruited. Cardiac output (CO) measurements were made using a 2MHz continuous wave suprasternal doppler at the AV and PV in triplicate at three intervals post delivery (12, 24 & 48hrs). All measurements were performed with the neonate asleep. Statistical analysis included RMANOVA and Tukey-Kramer tests (P<0.05).
Results: The pooled results for subjects over the three time intervals were used to create 95% reference intervals (ref range) as shown in the table.
No significant difference was found between measurements at either AV or PV at any time measurement.
Discussion: The left and right heart cardiac output results when corrected for neonatal weight were comparable at around 230ml/min/Kg. This suggests that no shunt was occurring via the ductus arteriosus although previous studies have found shunt present up to 15 hours post delivery(1,2). Although the USCOM can be used for non-invasive cardiac output measurement in the term, healthy neonate, further work is required to see if these reference ranges also apply to pre-term neonates. Other applications include detecting differences in neonatal cardiac output following vasopressors used to prevent maternal hypotension during spinal anaesthesia for caesarean section.
1. Gessner I, Krovetz LJ, Benson RW, Prystowsky H, Stenger V, Eitzman DV. Hemodynamic adaptations in the newborn infant. Pediatrics 1965; 36: 752-62
2. Moss AJ, Emmanouilides G, Duffie ER. Closure of the ductus arteriosus in the newborn infant. Pediatrics 1965 32: 25