Influence of blood withdrawal and anticoagulant on clotting activity, hematologic data, and certain rheologic measurements.

The influence of blood withdrawal (vacuum or slow aspiration) and anticoagulants (ethylenediaminetetraacetic acid [EDTA]; heparin; citrate; a mixture of citrate, theophylline, adenosine, and dipyridamole [CTAD]; and D-phenylalanyl-L-prolyl-L-arginine chloromethyl ketone [PPACK]) on clotting activity, hematologic data, and rheologic measurements (whole blood and plasma viscosity, red cell filtration in one study) were investigated. No difference was found between the two blood withdrawal techniques on the basis of the affected measurements. EDTA appeared to be the best anticoagulant with regard to blood cell preservation and showed the lowest whole blood viscosity over a wide range of shear rates (0.1 to 87.0 sec-1). PPACK was the most potent inhibitor of clotting activity as monitored by fibrinopeptide A concentration. The results suggest that EDTA is probably a reasonable choice for rheologic studies of whole blood and should be combined with PPACK when plasma properties are studied.