Real time measurement of heparin concentration during cardiopulmonary bypass

A heparin/protamine titration system for measurement of heparin levels (Hepcon) is promising for efficient anticoagulation during cardiopulmonary bypass (CPB).

Fifty-seven patients subjected to CPB were divided into two groups, control (n = 24) and Hepcon groups (n = 33). The Hepcon group was further divided into three subgroups according to perfusion temperature. For the control group, conventional administration of an anticoagulant (300 IU/kg of heparin) and reversal protocol (heparin 1: protamine 1) was performed. For the Hepcon group, a heparin dose-response assay directed the initial dose of heparin. Hepcon also determined the dose of protamine by the titration. The initial dose of heparin in the control group (300 IU/kg) was statistically less than that of Hepcon group (360+/-80 IU/kg).

In the Hepcon group, the sensitivity to heparin was correlated with coagulation time (r = -0.78) and antithrombin III levels (r = 0.70), and individual difference of sensitivity resulted in a wide range of dosage (160 to 490 IU/kg). A strong correlation was observed between plasma and whole blood concentration of heparin (r = 0.86). However, they did not correlate with ACT values. Perfusion temperature didn't affect the heparin level, but did the ACT value. In the Hepcon group, the dose of protamine was significantly less and adverse events were rare.

In conclusion, whole blood heparin measurements correlated well with plasma heparin concentration. Protamine titration of heparin reduced the dose of protamine and decreased the chance of adverse reactions.