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A402
October 18, 2009 9:00 AM - 11:00 AM Room Area F |
| Stability of Samples over Time and Reproducibility of Rotation Thrombelastography (ROTEM®) |
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* Oliver M. Theusinger, M.D., Johannes Nürnberg, M.D., Lars M. Asmis, M.D., Burkhard Seifert, Ph.D., Donat R. Spahn, M.D., F.R.C.A. Anesthesiology, University Hospital Zurich, Zurich, ZH, Switzerland |
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Introduction
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Thrombelastometry (TEM) is a whole blood assay to evaluate the viscoelastic properties during blood clot formation and lysis. Rotation thrombelastography (ROTEM®, Pentapharm GmbH, Munich, Germany) has overcome some of the limitations of classic TEM. So far no clinical validation on reproducibility (inter and intra assay variability) and sample stability over time has been performed.
Methods: To evaluate pre-analytic aspects sample stability over time was assessed in 48 patients (24 males, 24 females) in 8 age groups (below 20 years; 20 – 30 years; 30 – 40 years; 40 – 50 years; 50 – 60 years; 60 – 70 years, 70 – 80 years and above 80 years). Citrated blood was stored at room temperature and FIBTEM, EXTEM and INTEM were measured every 30 minutes from T 0 minutes up to T 120 minutes on two ROTEM® devices. Measured ROTEM® parameters were: CT = Clotting time, CFT = Clot formation time MCF= Maximum clot firmness, a-angle = Angle alpha, CFR= Clot formation rate, A5= amplitude after 5 minutes of CT, A10 = amplitude after 10 minutes of CT, A15 = amplitude after 15 minutes of CT, A20 = amplitude after 20 minutes of CT, A25 = amplitude after 25 minutes of CT, A30 = amplitude after 30 minutes of CT. In 10 volunteers precision by intra and inter assay variability was evaluated at two points of time. Finally the effect of age and sex was evaluated. Results: ROTEM® parameters were stable over 120 minutes and no significant differences in ROTEM® results were found. Reproducibility of MCF was 97% in EXTEM, 95% in INTEM and 94 % in FIBTEM. Coefficient of variability (CV) of MCF was < 3% in EXTEM, < 5% in INTEM and <6% in FIBTEM. CV of CFT was < 4% in EXTEM and < 3% in INTEM. CV for angle alpha was <3% in EXTEM and <6% INTEM. CV of CT was < 15% in EXTEM and INTEM. Small but significant differences between ROTEM® devices were found for MCF in FIBTEM and INTEM as well as CFT and alpha angle in INTEM. As tests for the 48 patients ran over 60 minutes, at each point of time the percentage of the final MCF was calculated and indicated that after 10 minutes of running time MCF in EXTEM, INTEM and FIBTEM reached at least 98% of the final MCF value. With advancing age MCF increased significantly in all tests (p<0.001) by a mean of 0.1 mm per year of age over 20 years. CFT decreased significantly (p<0.05) in EXTEM and INTEM, with a mean of -0.4 sec per year of age over 20 years in EXTEM and -0.2 sec per year of age over 20 years in INTEM. Age had no influence on CT. MCF and angle alpha were significantly higher and CFT lower (p<0.05) in EXTEM and INTEM in women than in men indicating a somewhat greater coagulability in women. Similar changes in FIBTEM (towards hypercoagulability) did not reach statistical significance. CT was similar in all age groups and in both sexes. Conclusions: ROTEM® yields stable results over 120 minutes with a minimal variability on the same ROTEM® device. However, small but significant differences between ROTEM® devices were observed. Analysis should be performed on the same ROTEM® device if small differences are of importance for treatment. From Proceedings of the 2009 Annual Meeting of the American Society Anesthesiologists. |