Abstract
BackgroundViscoelastic near-patient assays of global hemostasis have been found useful and cost-effective in perioperative settings. Shortcomings of current systems include substantial laboratory intensity, user-dependent reproducibility, relatively large sample volumes, sensitivity to ambient vibration and limited comparability between techniques and devices. The aim of this study was to assess feasibility of a new, resonance-based viscoelastic whole blood methodology (TEG6s) in cardiac surgery with cardiopulmonary bypass (CPB) and to compare the parameters this system produces with the ROTEM delta system and standard coagulation tests.MethodsIn a prospective evaluation study, twenty-three consecutive cardiac surgery patients underwent hemostasis management according to current guidelines, using the ROTEM delta system and standard coagulation tests. Blood samples were collected prior to CPB before anesthetic induction (pre-CPB), during CPB on rewarming (CPB), and 10 minutes after heparin reversal with protamine (post-CPB). ROTEM and standard coagulation test results were compared with TEG6s parameters, which were concurrently determined using its multi-channel microfluidic cartridge system.ResultsTEG6s provided quantifiable results pre-CPB and post-CPB, but only R (clotting time) of CKH (kaolin with heparinase) was measurable during CPB (full heparinization). Spearman’s correlation coefficient (rs) was 0.78 for fibrinogen levels and MA CFF (functional fibrinogen). Correlation of several TEG6s parameters was good (0.77 to 0.91) with MCF FIBTEM, and poor (<0.56) with prothrombin time and activated partial thromboplastin time (<0.44). Rs with platelet count was moderate (0.70, MA CK; 0.73, MA CRT). Accuracy of MA CFF for detection of fibrinogen deficiency < 1.5 g/L was high (ROC-AUC 0.93).ConclusionsThe TEG6s system, which is based on resonance viscoelastic methodology, appears to be feasible for POC hemostasis assessment in cardiac surgery. Its correlations with standard coagulation parameters are quite similar to those of ROTEM and there is good diagnostic accuracy for fibrinogen levels lower than 1.5 g/L. During full heparinization, TEG6s testing is limited to R measurement. Larger studies are needed to assess superiority over other POC systems.
Highlights
In a prospective evaluation study, twenty-three consecutive cardiac surgery patients underwent hemostasis management according to current guidelines, using the regard to maximum clot firmness (MCF) FIBTEM (ROTEM) delta system and standard coagulation tests
The TEG6s system, which is based on resonance viscoelastic methodology, appears to be feasible for POC hemostasis assessment in cardiac surgery
[1] Current guidelines recommend monitoring of hemostasis using viscoelastic hemostatic assays (VHA) in conjunction with coagulation management algorithms, with the aim to reduce patients‘transfusion exposure. [2,3,4] Point-of-care (POC) coagulation monitoring with VHA is increasingly used to guide administration of factor concentrates, especially in response to severe perioperative bleeding in cardiac surgery. [5,6,7]
Summary
Cardiac surgery with cardiopulmonary bypass (CPB) is frequently complicated by coagulopathic bleeding, which may require transfusion of allogenic blood products and may worsen outcome. [1] Current guidelines recommend monitoring of hemostasis using viscoelastic hemostatic assays (VHA) in conjunction with coagulation management algorithms, with the aim to reduce patients‘transfusion exposure. [2,3,4] Point-of-care (POC) coagulation monitoring with VHA is increasingly used to guide administration of factor concentrates, especially in response to severe perioperative bleeding in cardiac surgery. [5,6,7]Compared to standard laboratory coagulation testing, VHA provides comprehensive in vitro evaluation of patients’ functional hemostasis rapidly enough to guide emergency treatment. [8,9] During and after CPB, graphically displayed VHA results allow intuitive interpretation and proposal of specific interventions (fibrinogen supplementation, additional protamine administration) to improve coagulation rapidly. [10,11,12,13]Established VHA instruments such as thromboelastography (TEG, Haemonetics Inc., Braintree, MA, USA) or thromboelastometry (ROTEM TEM International GmbH, Munich, Germany) assess hemostasis properties by measuring shear forces between a pin and a bloodfilled cup. Clot-strength-specific resonance frequencies are detected by a photodetector and converted into TEG-equivalent units. The latter are used to generate TEG tracings, which are illustrating the viscoelastic change of the blood sample in real time. Shortcomings of current systems include substantial laboratory intensity, user-dependent reproducibility, relatively large sample volumes, sensitivity to ambient vibration and limited comparability between techniques and devices. The aim of this study was to assess feasibility of a new, resonance-based viscoelastic whole blood methodology (TEG6s) in cardiac surgery with cardiopulmonary bypass (CPB) and to compare the parameters this system produces with the ROTEM delta system and standard coagulation tests
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