Comparative Study of Thromboelastography with Routine Coagulation Tests for Hemostasis in Cardiopulmonary Bypass

Abstract

Postoperative hemorrhage after eardiopulmonary bypass(CPB) is one of the major causes of morbidity and mortality. Approximately 3% of patients have undergone surgical reexploration after open heart surgery. Coagulopathies after CPB are due to multiple hemostatic defects caused by hemodilution of procoagulants, firbrinogen, platelet, drugs and mechanical destruction by CPB machine. Thromboelastography(TEG) is the measures of viscoelastic properties of blood coagulation by providing information on the interaction of all the coagulation precursors and gives more clinically useful information on coagulation than that available from routine coagulation tests (RCT) or activated coagulation time(ACT). TEG is simple to use and can be performed within 30 minutes of blood sampling. Thirty-five patients of open heart surgery(12 were cyanotic and 23 were noncyanotic patients) were studied for the coagulation with TEG, ACT and RCT before and after CPB. Reaction time(R time), Coagulation time(R+K time), Maximum amplitude(MA), A60(Amplitude 60 min after MA), A60/MA index(Whole blood clot lysis index) and alpha angle were mea- sured in TEG, and at the same time RCT and ACT were also measured. Statistical analysis were performed by Student-t test for, significance, and 6 of TEG and 5 of RCT measurements were evaluated by multiple regression analytic methods(stepwise methods) for the correlation. The results were as follows: 1) TEG measurements before CPB were R time; 9.5±2.0min., R+K time; 14.6±2.7 min., MA; 52.4±3.6mm., A60; 45.1±4.5mm, Alpha; 46.2±5.50 and after CPB R time, 12.3±3.6min., R+K time, 24.3±16.4min., MA; 41.7±5.8min, A60; 36.4±4.4mm, Alpha, 32.0±8.90, respectively. There were significant differences between the measurements before and after CPB(P<0.005). 2) Before and after CPB, There was no significant difference between cyanotic and noncyanotic group in TEG 3) There was no fibrinolysis after CPB on TEG 4) There was significant correlation at the level of 95% significance after CPB following as; (1) R time vs aPTT and fivrinogen (2) R+K time vs PT, platelet and fibrinogen (3) MA vs platelet and PT (4) A60 vs platelet and fibrinogen (5) Alpha angle vs PT, aPTT, fibrinogen and Platelet 5) As the result of Multiple Regression Analytic Methods, R+K time, MA and Alpha angles after CPB could predict aPTT of RCT at the level of 99.5% signficance, In summary, thromboelastography is simple and easy to use in operating room for the diagnosis of coagulopathies compared with RCT.