Blood coagulation during and after normovolemic hemodilution in elective surgery

Hemodilution might extend the process of coagulation depending on three possible factors, namely 1) decreased concentration of clotting factors, 2) increased capillary flow and 3) specific actions of the dilutional agent on the clotting mechanism. In two randomized groups of patients undergoing hip arthroplasty preoperative normovolemic hemodilution with dextran 70 was compared to conventional bank blood transfusion. Coagulation parameters, blood loss and incidence of postoperative thromboembolism were studied. Minor reductions of the individual coagulation factors in the immediate postoperative course as well as a protracted APT-time were demonstrated in the hemodiluted group, but total surgical blood loss was not influenced by the hemodilution technique. The frequency of postoperative deep venous thrombosis did not differ between the groups, but there was a significant reduction in the number of silent pulmonary emboli in the hemodilution group.