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Comparison of viscoelastic measures of coagulation after cardiopulmonary bypass
K J Tuman1, B D Spiess, R J McCarthy
1Department of Anesthesiology, Rush-Presbyterian-St. Luke's Medical Center, Chicago, IL 60612.
Insights
Thrombelastography (TEG) and Sonoclot analysis (SCT) accurately predict postoperative bleeding after cardiopulmonary bypass (CPB). These viscoelastic tests are superior to routine coagulation tests (RCT) for managing bleeding complications.
Area of Science:
- Cardiovascular Surgery
- Hematology
- Anesthesiology
Background:
- Postoperative hemorrhage is a significant complication following cardiopulmonary bypass (CPB).
- Current empiric treatments are necessitated by the lack of rapid intraoperative coagulation monitoring beyond activated clotting time (ACT).
Purpose of the Study:
- To compare the efficacy of Thrombelastography (TEG) and Sonoclot analysis (SCT) against routine coagulation tests (RCT) in predicting postoperative hemorrhage after CPB.
- To assess the utility of viscoelastic hemostatic assays in managing coagulation defects in CPB patients.
Main Methods:
- Prospective study of 42 high-risk patients undergoing CPB.
- Blood samples analyzed for RCT (ACT, PT, PTT, FIB, PLT), TEG, and SCT before heparinization and after protamine administration.
- Comparison of test results with clinical assessment of postoperative bleeding.
Main Results:
- Routine coagulation tests (RCT) showed normal mean values post-CPB, despite bleeding in 9 patients.
- TEG and SCT identified abnormalities reflecting platelet-fibrin interactions in bleeding patients.
- Both TEG and SCT demonstrated 100% accuracy in predicting bleeding and were significantly better predictors than RCT.
Conclusions:
- Viscoelastic clot strength determinants can be abnormal after CPB.
- SCT and TEG are more effective than RCT for detecting and managing coagulation defects associated with CPB, improving prediction of postoperative hemorrhage.
Abstract:
Postoperative hemorrhage remains a major cause of morbidity after cardiopulmonary bypass (CPB). Treatment remains empiric because of the need for immediate correction and the lack of availability of rapid intraoperative coagulation monitoring (except for ACT) at most institutions. Thrombelastography (TEG) and Sonoclot analysis (SCT) are measures of viscoelastic properties of blood which allow rapid intraoperative evaluation of coagulation factor and platelet activity as well as overall clot integrity from a single blood sample. Routine coagulation tests (RCT) including activated clotting time (ACT), prothrombin time (PT), partial thromboplastin time (PTT), fibrinogen level (FIB), and platelet count (PLT) were determined and compared to TEG and SCT to assess which best predicted clinical hemostasis after CPB. Forty-two patients prospectively felt to be at high risk for excessive post-CPB bleeding had blood obtained for RCT, TEG, and SCT analysis before systemic heparinization and 30 min after protamine administration. Nine of 42 patients had excessive chest tube drainage, but no reoperations were required. After CPB, mean values for RCT were normal, but there were abnormalities in TEG and SCT parameters that reflect platelet-fibrin interaction. Both TEG and SCT were 100% accurate in predicting bleeding in these nine patients and, overall, both tests were significantly better predictors of postoperative hemorrhage than RCT. We conclude that viscoelastic determinants of clot strength may be abnormal after CPB and that SCT and TEG are, therefore, more useful than RCT for the detection and management of coagulation defects associated with CPB.