Prediction of bleeding diathesis in patients undergoing cardiopulmonary bypass during cardiac surgery: viscoelastic measures versus routine coagulation test.
ABSTRACT Severe hemorrhagic tendency often complicates cardiopulmonary bypass (CPB) in cardiac surgery. In this study, we compared the effectiveness of thromboelastography (TEG), Sonoclot (SCT), and routine coagulation test (RCT) in the prediction of coagulation defects.
Forty-three patients undergoing cardiac surgery with CPB were included. Blood for RCT, TEG, and SCT profiles was sampled before systemic heparinization and after protamine administration. Clinically significant bleeding was defined as chest tube drainage in excess of 100 ml/h for 3 consecutive hours or 300 ml/h in 1 h. All coagulation parameters obtained before and after CPB were compared. The sensitivity, specificity, accuracy, false positive, and false negative rate were also calculated and compared.
All coagulation tests were within normal range except higher partial thromboplastin time. Variables which were significantly different from those before CPB included platelet count, fibrinogen level, prothrombin time, and thrombin time in RCT, alpha angle and maximum amplitude in TEG, and R2 and peak time in SCT. In the TEG tracing, all variables had high sensitivity, specificity, and accuracy (average 85.4%, 83%, and 83.5% respectively) and low false positive and negative rate (12.5% and 5% respectively). Although SCT had high sensitivity (76.3%) and low false negative rate (6.5%), its specificity and accuracy were all under 50%.
Our data demonstrated that the TEG monitoring is a useful tool for detecting post-CPB bleeding diathesis and can provide much predictive information. RCT and SCT are of limited value because of higher rate of unreliable results.
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ABSTRACT: Protamine is routinely administered following cardiopulmonary bypass in order to neutralize the effects of heparin. An excess of protamine can contribute to coagulopathy, hence predisposing to bleeding with associated morbidity and mortality. Thromboelastography (TEG) is recognized as an invaluable bedside tool to detect coagulation parameters; however, the effects of protamine overdose on TEG parameters have not been fully established. Forty-six patients undergoing cardiac surgery using cardiopulmonary bypass were recruited in the study. Following heparinization, the patient's blood heparin level was measured using Hepcon HMS. Incremental doses of protamine [at a protamine-to-Hepcon-derived heparin ratio (PHR) of 1:1, 2:1 and 3:1] were added to patients' blood samples in vitro and four TEG coagulation parameters, including R (time to clot initiation), K (clot kinetics), alpha (clot kinetics) and maximum amplitude (ultimate clot strength), were monitored. Statistical analysis was performed using NCSS software. Protamine caused dose-dependent worsening of coagulation parameters on TEG; K was significantly elevated, whereas alpha and maximum amplitude showed significant reduction (P < 0.001) compared with baseline at a PHR of 2:1 and 3:1, respectively. R was significantly prolonged compared with baseline (P < 0.001) at a PHR of 3:1. Protamine adversely affects clot initiation time, clot kinetics and platelet function in a dose-dependent manner, which can predispose to bleeding.European Journal of Anaesthesiology 07/2010; 27(7):624-7. · 2.79 Impact Factor
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ABSTRACT: To investigate potential mechanisms for the differences in thromboelastography variables observed between arterial blood samples and venous blood samples. Prospective cohort study. University hospital. Patients undergoing cardiac surgery (n = 33). After the withdrawal of 10 mL of discarded blood (>3 deadspace volumes), 3 blood samples were withdrawn simultaneously from the central venous port of the pulmonary artery catheter (CVP), the radial arterial catheter (ART), and the side port of the 9F sheath introducer (SI). Thromboelastography was done simultaneously on each sample. All thromboelastography analyses were performed with 1% celite and heparinase according to the manufacturer's guidelines. A total of 80 ART, SI, and CVP comparisons were obtained. Mean hematocrit values were not different between sampling sites (27 +/- 4 v 27 +/- 4 v 27 +/- 3). Thromboelastography R time values (mean +/- SD) were CVP, 8 +/- 3; ART, 10 +/- 3; and SI, 13 +/- 5 (p = 0.004). Thromboelastography maximal amplitude (MA) values (mean +/- SD) were CVP, 60.4 +/- 11.7; ART, 56.2 +/- 11.4; and SI, 50.5 +/- 13.2 (p = 0.008). Calculated maximal shear stresses were CVP, 48 dyne/cm(2); ART, 36 dyne/cm(2); and SI, 0.3 dyne/cm(2). Blood samples obtained from the CVP (highest shear stress) resulted in faster (shorter R) and stronger (larger MA) coagulation compared with the arterial site (intermediate shear stress) and sheath introducer (lowest shear stress). These data show that differences exist in thromboelastography values between arterial and venous blood samples and, more importantly, show that the differences observed are not related to differences in oxygen content. These differences seem to be related to differences in catheter lumen diameter and, presumably, shear forces.Journal of Cardiothoracic and Vascular Anesthesia 10/2002; 16(5):551-4. · 1.45 Impact Factor
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ABSTRACT: Multiple blood products are often required during and after ventricular assist device (VAD) implants. Generally, transfusion therapy is empirically guided by conventional laboratory tests. In this study, we aimed to compare a thromboelastography (TEG)-based algorithm with a laboratory coagulation test-based algorithm with respect to blood product utilization in patients undergoing VAD implant. From June 2010 to May 2012, a total of 39 consecutive patients underwent VAD implantation. Patients undergoing VAD implant were retrospectively divided into two groups according to transfusion strategy. In the control group (n=20), the need for blood transfusion was based on clinician's discretion according to standard coagulation test results. In the TEG group (n=19), a strict protocol based on TEG parameters was followed for the usage of all perioperative blood products. Coagulation factors, TEG parameters, and blood transfusions were documented and compared between these two groups. There were no differences in demographic variables with the exception of a decreased CPB time in the TEG group (p=0.019). Prothrombin time (PT) (p<0.001) and international normalized ratio (INR) (p<0.001) in the postprotamine interval were significantly higher in the TEG group than in the control group. No significant difference was detected in any coagulation variable in the postoperative (ICU) period between the two groups. Platelet counts decreased in a linear fashion from baseline to the postoperative period in the two groups (p<0.001). Patients in the TEG group received significantly less fresh-frozen plasma in both the intraoperative (p=0.005) and postoperative (p=0.014) periods. Patients in the TEG group also received significantly less platelets both in the postoperative (p=0.03) period and in total amount (p=0.033). There was no difference in consumption of packed red blood cell units between the two groups. Our results show that the strict use of a TEG-guided algorithm significantly reduces the consumption of blood products in patients undergoing VAD implantJournal of Cardiac Surgery 03/2014; 29(2):238-43. · 1.35 Impact Factor