Background: Bedside thromboelastography is increasingly used, but an assessment of the clinical interchangeability of the 2 major systems, TEG (Hemoscope) and RoTEM (Pentapharm), has not been performed.
Methods: We measured blood samples from 46 cardiac surgical patients after induction of anesthesia with kaolin TEG(R) (kaoTEG), native TEG(R) (natTEG), intrinsic RoTEM (inTEM), and extrinsic RoTEM (exTEM). Each measurement consisted of reaction time (R), coagulation time (K), maximum amplitude (MA), and angle (alpha). Bland-Altman plots and mixed-model analysis were used. To assess repeatability, we made 7 replicated measurements in rapid succession in 2 volunteers.
Results: One hundred sixty-six measurements were available for analysis. The R time of the kaoTEG (345 + or - 102 seconds, mean + or - sd) was longer than that of the inTEM (179 + or - 74 seconds, P < 0.001) and the exTEM (55 + or - 28 seconds, P < 0.001). The K time of the kaoTEG (78 + or - 18s) was not different from that of the inTEM (75 + or - 52 seconds, P = 0.60) but was longer than the K time of the exTEM (61 + or - 24 seconds, P < 0.003). The MA of the kaoTEG (71 + or - 6.5 mm) was larger than the MA of the inTEM (67 + or - 5.2 mm, P < 0.02) and almost similar to that of the exTEM (69 + or - 6.3 mm). The alpha of the kaoTEG (72 degrees + or - 4.1 degrees ) was not significantly different from that of both the inTEM (76 degrees + or - 7 degrees ) and the exTEM (79 degrees + or - 4.5 degrees ). The variability for MA and alpha was <10%. The repeatability of the R and K times was poor in both devices, whereas the repeatability of the MA and alpha was sufficient for clinical purposes.
Conclusions: The TEG and RoTEM measurements demonstrated a close correlation for the MA, but the alpha did not for the R and K variables. The kaoTEG had the best agreement with the exTEM measurement. Therefore TEG and RoTEM measurements are not completely interchangeable, and the clinical interpretation of thromboelastograhic data should be used with caution.