Optimization of heparin anticoagulation during membrane plasma separation.

This study analyses 75 membrane plasma exchanges carried out in 18 patients where various amounts of heparin were used to define the heparin kinetic during plasma exchange and the appropriate anticoagulation. A specific assay was employed to measure heparin concentration. Our results showed that: 1) the heparin distribution volume exceeded the expected value by 10 to 25%; 2) the drug is filtered with a sieving coefficient = 1; 3) the appropriate concentration range is within 0.2 and 0.5 Ul/ml.; 4) the heparin blood levels strictly correlate with a PTT (p less than 0.001); 5) the individual need for heparin is related to the patient Hct (p less than 0.001) and plasma flow (p less than 0.001). Simple guidelines are provided to determine the appropriate heparin dosage in single patients.