Hemostatic alterations during continuous venovenous hemofiltration in acute renal failure.

In order to determine changes in hemostasis occurring during continuous venovenous hemofiltration (CVVH), we made a prospective study of 14 patients with acute renal failure. Fibrinopeptide A, thrombin-antithrombin III complex, beta-thromboglobulin and platelet retention were determined serially. Fibrinopeptide A (x +/- SD: 33 +/- 20 ng/ml, ref. < 3.0) and thrombin-antithrombin III complex (11 +/- 5 ng/ml, ref. 1.0-4.0) were enhanced prior to commencement of treatment but showed no further increase during therapy. Platelet retention (Hellem II, ref. 60-99%) fell from 39 +/- 32% before treatment to 16 +/- 15% after treatment, while the beta-thromboglobulin/creatinine ratio (ref. 0.23-0.41) rose from 0.39 +/- 0.20 to 0.64 +/- 0.44. Via platelet activation, CVVH leads to a reinforcement of the existing platelet dysfunction (thrombocytopathy), without influencing plasmatic coagulation. In order to analyze the influence of pre-existing hemostatic alterations on filter running time during CVVH, 60 patients were examined retrospectively in a second study. Filter running time, global coagulation tests, fibrinogen, antithrombin III, platelet count and hematocrit were registered daily. There was no significant correlation between filter running time and fibrinogen concentration, thrombin time, platelet count or hematocrit. Apart from filter occlusion, no thrombotic complications were observed. The frequency of filter occlusion increased with falling activated clotting time (ACT) (p < 0.05). Rising platelet count led to an increase in heparin dose (p < 0.05), primarily due to the anti-heparin effect of platelet factor 4.