Pulsed Doppler ultrasound blood flow measurements in the superior mesenteric artery of the newborn.

In 25 healthy newborns transcutaneous Doppler ultrasound measurements (Duplex-Scan) of flow velocities in the superior mesenteric artery were performed to define normal values and to investigate the response of intestinal blood flow to feeding. The diameter of the vessel was measured from real-time and M-mode imaging: mean value 3.2 mm. The analysis of the flow patterns before and after feeding revealed a significant change of the blood flow with increase of the peak velocity (Vp) (from 57 +/- 3.1 cm/sec to 97 +/- 11.5 cm/s) and the mean velocity (Vm) (from 22 +/- 1.6 cm/s to 41 +/- 4.1 cm/s). The pulsatility index decreased from 0.85 in the fasting baby to 0.73 45 min after feeding. The Vm was correlated with the post natal age and depended upon the quantity and quality of the meals. Neonates when fed only with tea/glucose 5% or small amounts of milk in the first 24 h, showed a fasting Vm of about 17-18 cm/s. Neonates older than two days who were fed with increasing amounts of milk showed a mean pre feeding Vm of 30 +/- 3.8 cm/s.