[Comparative efficiency of 1 direct and 2 indirect methods for the detection of differences in erythrocyte aggregation, in normal blood and in blood with echinocytosis].

BACKGROUND

There are many different methods for assessing red cell aggregation, but they have been evaluated in isolated form. The aim of this work was to compare the efficacy and reliability of three different methods for evaluating red cell aggregation.

MATERIAL AND METHODS

Blood was drawn on trisodium citrate, and after removal of platelet-rich plasma, the red cell were washed with sodium chloride, and blood was reconstituted until a haematocrit of 40% was achieved. Aspirin or dipyridamole were added, the latter for inducing echinocyte formation. Three methods of assessment of red cell aggregation were used; two of them, indirect, were based upon blood viscosimetry under shear rates indices, and sedimentation rate of centrifuged blood. The third, direct method was based on microscope observation of aggregation and digital analysis of its images for statistical evaluation. Both descriptive methods and analysis of variance were used.

RESULTS

The addition of aspirin and dipyridamole increased blood viscosity with respect to the control (p < 0.001 and p < 0.005, respectively), thus showing increased red cell aggregation. Sedimentation rate was also increased, with, statistical significance in the case of dipyridamole (p < 0.05). Digital analysis of images showed significant increase of red cell aggregation with aspirin (37.48 +/- 2.16 vs 27.99 +/- 1.55 in controls, p < 0.05). The presence of dipyridamole-induced echinocytes impeded an adequate evaluation of red cell aggregation indices.

CONCLUSION

It was included from these studies that blood viscosimetry proved to be as efficient as digital analysis of images for assessing the differences in red cell aggregation. Nevertheless, microscope examination was necessary for a correct evaluation of this phenomenon, and the presence of echinocytes invalidated any attempt to compare red cell aggregation with respect to normal blood.