Prognostic significance of intra-operative blood transfusions and flow measurements in reconstructive vascular...

Intra-operative measurement of leg blood flow is useful not only for the detection of a technical fault. It has also proved to be a sensitive method to disclose hypovolaemia. Thus, if the blood volume is not restored, the peripheral vasoconstrictor tone remains elevated. In such a state, the basal leg blood flow is low, but increases markedly on pharmacological vasodilation. In a normovolaemic situation, however, the basal blood flow is higher with a less pronounced increase following vasodilation. In the present study, intra-operative measurements of graft blood flow using an electromagnetic flowmeter have been employed to evaluate the blood substitution needed during 114 consecutive reconstructions with femoro-popliteal reversed saphenous vein bypass grafts. The measurements resulted in a blood transfusion therapy that was, on an average, 38% higher that it would have been, if substitution had been based simply on a calculation of blood losses from volume measurements in the suction apparatus and from the drapes and swabs. Only three graft thromboses developed within the first month. The flow rate of these grafts was much lower than the grafts remaining open. The low early thrombosis frequency (2.8%) compares favourably with previous reports, which might partly be explained by generous intra-operative blood transfusion.