Reproducibility and interchangeability of the Thromboelastograph (R), Sonoclot (R) and Hemochron (R) activated coagulation time in cardiac surgery

Purpose: Despite their common use in cardiac surgery, few studies hove eval uated the reproducibility of the Thromboelastograph (R) (TEG), of the Sonoc lot (R) (SCT), and of the activated coagulation time with celite (ACT-C) or kaolin (ACT-K) measured with the Hemochron (R), in clinical conditions of on-site monitoring of hemostasis, This study determined the reproducibility of those measurements, and evaluated the ability of various devices to sub stitute for the ACT-C. Methods. Blood samples collected from 20 volunteers and 21 patients undergo ing myocardial revascularization were analyzed in the two channels of the T EG, in two SCT and four Hemochron (R) analyzers. The overall of TEG and SCT coagulation profiles were analyzed by a computerized TEG and an experience d observer respectively. The variation rate (V%) was calculated for each va riable. The ability of ACT-K and SCT to substitute for ACT-C under differen t clinical conditions was evaluated. Results. ACT-C andACT-K V% ranged between 5.6% and 10.8% and between 6.7% a nd 12.4% respective. TEG and SCT V% ranged between 3.1 % and 9.5% and betwe en 5.8% and 33.6% respectively, according to different conditions and param eters. In volunteers and nonheparinized patients, the ACT-C and ACT-K were interchangeable. No other test con substitute for the ACT-C when patients o re heparinized during cardiopulmonary bypass (CPB). Conclusions: In the clinical conditions of use, on-site hemostasis monitori ng devices providing the most reproducible measurements are, in decreasing order, the TEG, the Hemochron (R) and the SCT In heparinized patients and d uring CPB, results from different tests are not interchangeable, stressing the importance of establishing appropriate instrument-specific values for m onitoring anticoagulation during cardiac surgery.