Hirudin monitoring using the TAS ecarin clotting time in patients with heparin-induced thrombocytopenia type II.

OBJECTIVE

To assess the reliability of the TAS/ecarin clotting time (ECT) for on-line monitoring of r-hirudin in cardiovascular surgery with and without cardiopulmonary bypass (CPB).

DESIGN

Samples were spiked with r-hirudin (0 to 5 microg/mL) and calibration curves constructed. Reproducibility was evaluated by measurement of the sample five times at each concentration. The influence of variations in hematocrit, plasma factors, and platelet count on the test results was examined. Samples were obtained from patients during cardiovascular surgery with CPB (n = 8), without CPB (n = 3), and from volunteers (n = 5) and compared with the laboratory reference tests. All tests were performed in duplicate.

SETTING

Deutsches Herzzentrum Berlin.

PARTICIPANTS

Five healthy volunteers and 11 patients undergoing cardiovascular surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The TAS/ECT showed linearity and reliability to an r-hirudin concentration of 5 microg/mL and was not influenced (p < 0.005) by the varying conditions of the in vitro setup. The correlation to the laboratory method was 0.74 for the CPB group and 0.87 for the non-CPB group.

CONCLUSIONS

The TAS/ECT is a reliable assay for monitoring r-hirudin at the point of care. With this information, the use of r-hirudin during surgery or angioplasty should become more effective and safer.