Effect of time delay from venepuncture on red cell rheology

Abstract

The effect of storage of blood at room temperature on the measurement of erythrocyte rheology was assessed in 12 normal subjects. Red cell rheology was measured by filtration of whole blood (1), by a micropipette aspiration method (2), by centrifugal packing (3), and by viscometry of packed red cells (4). Measurements were made at 0.5–1.5 h after venepuncture, and again at 24h, using blood anticoagulated with 1.5 mg/ml K2EDTA (Seward Laboratory, London). A significant impairment in rheology was observed with the filtration (P<0.01) and micropipette (P<0.02) methods at 24 h but not with centrifugation or packed cell viscometry (Table 1). More detailed studies, where measurements were made at hourly intervals, showed that filtration began to deteriorate at 3 h in some individuals while others did not show changes until 8h. Using the micropipette method, the earliest changes were detected at 6–8 h from venepuncture. Several variables having a possible effect on erythrocyte deformability were measured within 0.5–l.5 h of venepuncture and at 24 h and are shown in Table 1.