Extremity venous blood temperature and blood clotting mechanisms

¹ Departments of Medicine and Pathology, Stanford University School of Medicine, Stanford; and Departments of Clinical Physiology and Pathology, Community Hospital of San Mateo County, San Mateo, California

The effect of extremity venous blood temperature on the clotting mechanisms was studied. In 20 normal adults, under ordinary indoor conditions, the mean temperatures and standard errors, as measured with needle thermistors, were: greater saphenous vein (lower 3rd of leg), 30.2°C ± 0.29; antecubital vein, 34.6°C ± 0.21; deep gastrocnemius muscle, 36.1°C ± 0.18. In 20 afebrile bed-confined patients the findings were: greater saphenous vein, 29.1°C ± 1.12; antecubital vein, 34.2°C ± 0.55, gastrocnemius muscle, 33.7°C ± 0.71. In the range from 22° to 37°C the following linear negative temperature coefficients were found: one-stage prothrombin time, 4%/°C; Lee-White clotting time, 7%/°C; whole blood viscosity, 0.15 centipoise/°C. In vitro clot cohesiveness, as indicated by resistance to compressive and longitudinal stresses, and in vivo clot adhesiveness, as indicated by resistance to dislodgment of clots formed in rabbit venae cavae, were significantly less for clots formed at 25°–30°C than for clots formed at core body temperature. Such effects of low temperature on blood viscosity and the clotting mechanisms have pertinence in regard to the problem of thromboembolism.