Doppler-derived cardiac output in healthy newborn infants in relation to physiological patency of the ductus arteriosus.

Noninvasive Doppler-derived cardiac output was measured with the pulsed Doppler method in 22 healthy newborns during their first four days of life. Maximal blood flow velocity in the aorta was measured with the Doppler ultrasound method. The mean Doppler-derived cardiac output was 273 +/- 59 ml/min/kg. Ductal left-to-right shunting was also determined and then graded according to the flow in the main pulmonary artery. The mean Doppler-derived cardiac output was 301 +/- 61 ml/min/kg when there was a moderate ductal left-to-right shunt, 266 +/- 59 ml/min/kg when the shunting was mild, and 260 +/- 53 ml/min/kg when there was no shunting ductus. The Doppler-derived cardiac output was significantly higher when there was a moderate left-to-right shunt than without such shunting. This method seems to be a useful approach in monitoring the cardiac function of newborns without unduly disturbing their condition. Normal values on Doppler-derived cardiac output have to be judged in relation to the magnitude of ductal left-to-right shunt.