The effect of an infusion of low molecular weight dextran on peripheral resistance in patients with arteriosclerosis.

Low molecular weight dextran is frequently given to improve the flow of blood to the periphery, but its mode of action is uncertain. We measured the effect of an infusion of 500 ml of Dextran 40 on the peripheral resistance in 12 patients undergoing reconstructive surgery for atherosclerotic occlusion of the superficial femoral artery. After the infusion, values of packed cell volume and blood viscosity indicated haemodilution. There was a consistent increase in mean flow and a fall in peripheral resistance. There was no correlation between change in viscosity and change in peripheral resistance, but there was a good correlation between the percentage change in resistance and the initial resistance. This suggests that the increase in flow of blood was due to reflex vasodilatation rather than to any reduction in viscosity.