[The effect of operation, anaesthesia and blood viscosity on haemodynamic during aortofemoral bypass operation (author's transl)].

Cardiac index, total peripheral resistance, blood, plasma and serum viscosity in patients with peripheral vascular disease were measured pre-, intra- and postoperatively. Besides plasma and serum viscosity, most obviously blood viscosity decreased during anaesthesia and operation. The decrease of blood viscosity is caused mainly by the falling haematocrit. Red blood cell aggregation occuring under low-flow conditions is decreased. Thus blood viscosity additionally is diminished at least in the area of low shear rates. Corresponding haemodynamic measurements revealed that decreasing viscosity improves cardiac index and total pressure resistance if normovolaemia exists, but in general is masked by anaesthesia and operation.