Pulsatility index of superior mesenteric artery blood velocity waveforms.

A transcutaneous Doppler ultrasound technique was used to investigate superior mesenteric artery blood velocity waveforms in normal subjects. The shape of the waveforms was quantified by means of the pulsatility index (PI). The mean value +/- standard error of the mean of the PI measured in 82 normal subjects in the resting and fasting state was 3.57 +/- 0.11. There was no difference in the PI between sexes nor correlation between the PI and age. Following the ingestion of a meal in a group of 15 subjects the PI decreased by 46% (p less than 0.001). A significant fall persisted over the next two hours.