Abstract:
A pharmacokinetic model for minimal dose heparinization for chronic hemodialysis patients was described by Gotch and Keen. The model requires determination of two parameters : dose sensitivity [computed for a given heparin dose from an increase in activated clotting time (ACT) above a baseline value] and heparin elimination constant. We studied this model to the precise control of heparin during routine dialysis. Patient and method : Heparin sensitivity and elimination constant were measured in 30 stable chronic hemodialysis patients. To study the effect of heparin individualization upon the number of dialyzer reuse, we compared dialyzer reuse, we compared dialyzer clotting by measurment fiber bundle volume before and after adjustment heparin dosage. Result : Heparin sensitivity and elimination constant differed markedly. The heparin sensitivity value was 0.0487 +/- 0.0019 (mean +/- SD) and Ke value was 0.354 +/- 0.204 (mean +/- SD). Variation in sensitivity during dialysis were 4%, but variation in elimination rate of up to 57%. Heparin requirements adjusted by ACT were reduced by an average of 58% (range 2% to 84%). The mean heparin dosage before and after individualization of heparin are 5,120 +/- 636 and 2,163 +/- 1041 unit (P<0.001). There was no significant change in the degree of three types of dialyzer clotting in comparing premodeling and postmodeling heparin therapy. Conclusion : Heparin modeling has been successfully applied to routine anticoagulant during dialysis.