Abstract
Four rheological instruments for measuring erythrocyte deformability have been compared. Erythrocyte filterability was measured by a Hemorheometre and a St. George’s Filtrometer, erythrocyte viscosity by a Contraves LS 30 rotational viscometer, and erythrocyte radial spreading in filter paper by a Radial Spreading Rheometer. Each instrument showed adequate reproducibility, giving coefficients of variation for 10 replicate samples of < 5.5%. As in the case of other filtration instruments, the St. George’s Filtrometer was sensitive to leucocyte contamination of the erythrocyte suspension. When leucocyte-depleted erythrocytes were manipulated in vitro to give an incremental loss of deformability ranging from < 10% to > 100%, the St. George’s Filtrometer was found to be the most sensitive of the four instruments in six of eight test models. The different relative sensitivities of these instruments should now be evaluated in clinical studies.
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