Heparin cofactor activity during and after extracorporeal circulation with bubble and membrane oxygenators.

Heparin cofactor activity as measured by an amidolytic method has been investigated in 48 patients undergoing cardiac surgery with extra-corporeal circulation (E.C.C.). Heparin cofactor activity is reduced soon after the start of E.C.C., due to hemodilution but it returns towards initial levels at the completion of the procedure and 3 hours later. Thus heparin cofactor does not seem to play a role in the heparin rebound phenomenon. In our patients bubble oxygenators did not modify heparin cofactor activity more than did membrane oxygenators.