Automated Thromboelastometry for Semiquantitative Assessment of High Heparin Concentrations: A Feasibility Study in...

To date, thromboelastometry has not been investigated as an assay to monitor profound heparin anticoagulation, such as is required for a safe cardiopulmonary bypass (CPB). The aim of this study was to test the feasibility of automated thromboelastometry for semiquantitative assessment of increasing heparin concentrations.

Blood samples were collected from 20 healthy adult volunteers that were recruited to participate in the study. The citrated blood tubes were spiked with unfractionated heparin to concentrations of 0, 1, 2, 3, 4, 5 and 6 IU/mL. From each concentration, point-of-care viscoelastic testing was performed using the HEPTEM, INTEM, EXTEM, and FIBTEM cartridges of the fully automated ROTEM Sigma device. Linear mixed model with regression analysis and receiver operating characteristics (ROC) curves were used to analyze the data.

HEPTEM coagulation time (CT) was linearly prolonged by 5 s (95% CI, 4-6 s, p < 0.001) for each one unit increase in heparin concentration. The ROC curve on the ability of HEPTEM CT to detect heparin concentrations of ≥ 4 IU/mL had an area under the curve of 0.828 (95% CI, 0.761-0.895, p < 0.001), suggesting acceptable diagnostic performance. In contrast, all INTEM, EXTEM, and FIBTEM parameters were invalid in the detection of heparin concentrations adequate for CPB.

This study on automated thromboelastometry demonstrated a dose-dependent prolongation of HEPTEM CT when heparin concentration increased from 0 to 6 IU/mL. Furthermore, ROC analysis on the ability of HEPTEM CT to detect heparin concentrations of ≥ 4 IU/mL indicated possible diagnostic potential. These novel findings suggest that HEPTEM CT is a feasible ROTEM Sigma parameter for semiquantitative assessment of heparin concentrations required for safe CPB. However, this remains to be verified in future clinical studies.