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 year s were treated by continuous venovenous hemofiltration (CVVH) between 1986 and 1992 in our intensive care units. Blood was circulated throug h 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 antic oagulation (ie, prevention of extracorporeal circuit clotting without inducing a patient's bleeding tendency): group 1, 37 patients who rece ived 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, th e routine coagulation parameters, and the evolution of the patients fo r each group. Median duration of treatment was 144 hours (range, 4 to 1,152 hours). There were no differences in requirement of heparin amon g 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 rel ationships 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 p arameter that differed significantly between each of the three groups was the initial platelet counts (group 1, 42,000/mu L; group 2, 141,73 0/mu L; group 3, 211,000/ mu L; ANOVA P = 0.001). The initial prothrom bin 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 g roups. During CVVH, the platelet count decreased significantly from 14 1,730/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 rem ained stable. The highest mortality rate was found in group 1 (73%) co mpared 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 gr oup 3 (10%). In conclusion, the majority of patients had an adequate a nticoagulation with low-dose heparin, and in the presence of initial l ow platelet count, CVVH can be conducted without anticoagulation. Furt hermore, during CVVH, platelet counts significantly decrease in patien ts 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.