An in vitro study of the effects of Doppler angle, fibrinogen, andhematocrit on ultrasonic Doppler power

摘要

For a better understanding of the relationship between the Dopplernpower and erythrocyte aggregation of whole blood under steady flow in anconduit, the effects of Doppler angle, fibrinogen concentration, andnhematocrit were investigated in a mock flow loop. The results show that,nat a mean shear rate of 102 s-1, there was minimal angularndependence; but at a mean shear rate of 52 s-1, there was anweak angular dependence as the Doppler angle was varied from 40° ton70°. These results suggest that there was, perhaps, no or littlenalignment of the red cell aggregates at high shear rates. The Dopplernpower was found to increase nonlinearly as the fibrinogen concentrationnwas increased; and the effect of other plasma proteins on red cellnaggregation may not be negligible, although fibrinogen is the dominantnfactor. The results show that the variation of the Doppler power overnthe lumen is hematocrit dependent for hematocrits below 26%