Validity of Doppler measurements of superior mesenteric artery blood flow velocity: Comparison with blood flow measured by microsphere technique

Abstract

Objective: To validate Doppler measurement of superior mesenteric artery blood flow velocity as a measurement of superior mesenteric artery blood flow. Method: The superior mesenteric artery blood flow velocity, measured by the Doppler ultrasound technique, was validated with simultaneous measurement of blood flow by the microsphere method. Six newborn piglets were studied during baseline conditions, after 10 min of hypoxaemia and during continuous calcium blocker infusion. Results: Mean blood flow velocity ( r = 0.69, P < 0.0001), end-diastolic flow velocity (EDFV) ( r = 0.81, P < 0.0001) and resistance index ( r = 0.76, P < 0.0001) all correlated with superior mesenteric artery blood flow, whereas the peak systolic flow velocity did not correlate. Mean blood flow velocity did not significantly reflect all the changes in blood flow, probably because of changes in cross-sectional area of the superior mesenteric artery. The changes in EDFV followed the changes in blood flow more closely, although the decrease in EDFV (91% ± 12%) was of greater magnitude than the decrease in blood flow (55% ± 11%). Conclusions: Our results suggest that, although EDFV measurements in the superior mesenteric artery are not a predictor of quantitative changes in blood flow, it could be used to follow qualitative changes in intestinal blood flow under different clinical conditions.