ANTICOAGULATION IN PATIENTS TREATED BY CONTINUOUS VENOVENOUS HEMOFILTRATION - A RETROSPECTIVE STUDY

The most adequate anticoagulation regimen during extracorporeal renal replacement therapy can be difficult to define. Two hundred fifty-five critically ill patients with a mean age (+/-SD) of 58.2 +/- 16.3 years were treated by continuous venovenous hemofiltration (CVVH) between 1986 and 1992 in our intensive care units. Blood was circulated through hemofilters, either polyacrylonitrile (AN 69; Hospal, Lyon, France) or polyamide (FH 66; Gambro, Lund, Sweden), using a roller pump and an air safety system. The patients were classified into three subgroups according to the amount of heparin needed to achieve an adequate anticoagulation (ie, prevention of extracorporeal circuit clotting without inducing a patient's bleeding tendency): group 1, 37 patients who received no heparin (14.5%); group 2, 189 patients who received 100 to 700 IU/hr of heparin (74.1%); and group 3: 29 patients who received more than 700 IU/hr of heparin (11.4%). We analyzed the filter survival, the routine coagulation parameters, and the evolution of the patients for each group. Median duration of treatment was 144 hours (range, 4 to 1,152 hours). There were no differences in requirement of heparin among the two types of membrane: AN 69 (mean +/- SD), 393 +/- 106 IU/hr v FH 66, 374 +/- 35.3 IU/hr (range, 0 to 2,000 IU/hr). There were no relationships between the amount of heparin the patients received and the mean survival of the filters (group 1, 22.1 +/- 14.8 hr; group 2, 24.7 +/- 13.2 hr; group 3, 23 +/- 9.6 hr). The only routine coagulation parameter that differed significantly between each of the three groups was the initial platelet counts (group 1, 42,000/mu L; group 2, 141,730/mu L; group 3, 211,000/ mu L; ANOVA P = 0.001). The initial prothrombin time was lower in group 1 (45.5%) than in groups 2 (60.6%) and 3 (60.9%). The initial partial thromboplastin time was prolonged in all groups. During CVVH, the platelet count decreased significantly from 141,730/mu L to 113,735/mu L in group 2 and from 211,000/mu L to 122,000/mu L in group 3, in contrast to group 1, in which platelet counts remained stable. The highest mortality rate was found in group 1 (73%) compared with groups 2 (51.4%) and 3 (69%). Four deaths were attributed to bleeding in group 1 (14.8%), seven in group 2 (7.2%), and two in group 3 (10%). In conclusion, the majority of patients had an adequate anticoagulation with low-dose heparin, and in the presence of initial low platelet count, CVVH can be conducted without anticoagulation. Furthermore, during CVVH, platelet counts significantly decrease in patients receiving a high or normal dose of heparin, but not in patients who started with low platelet counts and who were not given heparin. (C) 1994 by the National Kidney Foundation, Inc.