Reply to Kozek-Langenecker et al letter ’Experience with Both Machines.’

keriashpole — Wed, 22 Apr 2009 11:20:52 GMT

We would like to thank Kozek-Langenecker et al for their letter and welcome their comments as they clearly have far greater experience in the use of thromboelastography than we do. The intention of our 'head-to-head' [1] was a direct comparison of basic information about both commercially available thromboelastographs, the ROTEM® and the TEG®. These machines are not interchangeable, with different mechanisms of action, activators and significant differences in trace results [2]. The service from the manufacturer in terms of training and reliable aftersales support was also afforded important consideration.

The ‘dedicated local customer service’ that the Austrian team received may reflect the fact that the headquarters of the company supplying the ROTEM are based in Munich, Germany, and that over the last 18 years strong links with their distributer have been developed. In the UK, TEG has a long established distributer and service provider (Haemoscope TEG®) but at the time of our comparison there was a changeover period between UK distributers for the ROTEM. However, equipment and training were provided directly from the parent company for the comparison, and communication/support from the new UK distributer (Pentapharm) has so far been exemplary.

In answer to Kozek-Langenecker’s specific questions: comparison of costs was kept to basic tests only, hence the omission of costs for the functional fibrinogen. The functional fibrinogen test for the TEG has been commercially available in the UK/Eire since January 2008 and when tested, we found the TEG had a warm up time of less than 5 min, corresponding with the published data.

The TEG may be used for assessing a patients’ current anticoagulant state as antiXa blood levels > 0.1U.ml^-1 are seen as a hypocoagulable TEG clotting pattern [3, 4]. In an urgent situation when laboratory antiXa assays are unavailable, a TEG may be a helpful adjunct to determining a parturient’s risk of bleeding during surgery/delivery.

There is no substitute for experience, and ‘discussion with experienced users’ is always useful, but in the UK few institutions have equal experience with both devices and there are no published direct comparisons of ease of use, local support/training and relevant costs. Differences in access to resources are highlighted by the fact that we are still unable to purchase either machine, whereas Kozek-Langnecker et al have used both ‘simultaneously for some years’.

K.J. Ashpole, S.M. Yentis, G. Jackson

References

1. Jackson G, Ashpole K, Yentis S. The TEG vs the ROTEM thromboelastography / thromboelastometry systems. Anaesthesia 2009; 64: 212-5.

2. Nielson VG. A comparison of the Thromboelastograph and the ROTEM. Blood Coagulation and Fibrinolysis 2007, 18:

3. Backe SK, Lyons GR. High-dose tinzaparin in pregnancy and the need for urgent delivery. British Journal of Anaesthesia 2002; 89: 331-4.

4. Klein SM, Slaughter TF, Vail PT et al. Thromboelastography as a Perioperative measure of anticoagulation resulting from low molecular weight heparin: A comparison with Anti-Xa concentrations. Anesthesia and Analgesia 2000; 91: 1091-5.

Experience with both machines

SKozek — Fri, 06 Mar 2009 17:47:01 GMT

We have used rotational thrombelastometry (ROTEM®) and thrombelastography (TEG®) for clinical and scientific purposes at the Vienna Medical University for 18 years and our experience differs from the report by Jackson et al [1]. Viscoelastic tests are most often used in bleeding management and in this indication, EXTEM and FIBTEM test are the basic tests for differential diagnosis [2] performed immediately after blood withdrawal. The functional fibrinogen test of TEG® (comparable with the FIBTEM) is still not commercially available, even for long term customers such as us; pipetting abciximab to the TEG® cup [3] is a possible but less convenient and standardised alternative. The cost effectiveness of ROTEM® has previously been shown in various surgical settings [4]. True cost analysis should compare kaolin vials plus functional fibrinogen in TEG® cups vs EXTEM plus FIBTEM in ROTEM® cups: the ROTEM® test panel apparently costs 50% (£11.40) less in the UK. In massive bleeding repeated measurements are recommended [2] and detection of hyperfibrinolysis may require long sample reading times (60 mins. Accordingly, at least two TEG® (2 test channels each) may be needed for adequate monitoring; this leads to about 20% (£5338) higher direct acquisition costs compared with one ROTEM® (4 test channels). The platelet mapping assay can be performed on either ROTEM® or TEG® [5], but we doubt that this very expensive test with limited test performance will gain widespread adoption in view of the alternatives. The effect of low molecular weight heparin has been detected in the TEG® with and without heparinase but indicative TEG® parameters were not proportional to anti Xa-concentrations and showed a high inter-individual variability and anti Xa-levels were more sensitive than TEG® [6, 7]. Low tissue factor-activated tests [8] may be more sensitive than kaolin-activated heparinase-modified viscoelastic assays.

We have experienced highly professional and dedicated local customer service for the ROTEM® system. Our university teaching experience clearly explains why training offered by the companies for the TEG® is longer than for the ROTEM®. For medical students and anesthesiologists it is much easier to learn the handling of the ROTEM®; for example due to automated pipetting, easy step-by-step instructions on the screen. Our experience in the trauma unit has shown that preparation of the TEG® multi-use vials required more handling and warm-up of the machines from cold took up to 15 min.

In conclusion, we recommend decision making before purchase based on the published evidence on point-of-care differential diagnosis in bleeding and on discussion with experienced users rather than on marketing information. When used simultaneously for some years we have seen the superiority of the ROTEM® in respect to usefulness, usability, and costs.

Sibylle Kozek-Langenecker

Eva Schaden

Gisela Scharbert

Department of Anaesthesiology, General Intensive Care and Pain Management, Vienna Medical University, Austria

References

1. Jackson G, Ashpole K, Yentis S. The TEG vs the ROTEM thromboelastography / thromboelastometry systems. Anaesthesia 2009; 64: 212-5.

2. Kozek-Langenecker SA. Management of massive operative blood loss. Minerva Anesthesiologica 2007; 73: 401-15.

3. Kettner S, Panzer OP, Kozek S, et al. The use of abciximab-modified thrombelastography in patients undergoing cardiac surgery. Anesthesia and Analgesia 1999; 89: 580-4.

4. Görlinger K, Jambor C, Hanke A, et al. Perioperative coagulation management and control of platelet transfusion by point-of.care platelet function analysis. Transfusion Medicine and Hemotherapy 2007; 34: 396-411.

5. Scharbert G, Auer A, Kozek-Langenecker SA. Evaluation of the platelet mapping assay on rotational thromboelastometry (ROTEM). Platelet 2009; 20: 125-30.

6. Zmuda K, Neofotistos D, Ts’ao CH. Effects of unfractionated heparin, low-molecular-weight heparin, and heparinoid on thromboelastographic assay of blood coagulation. American Journal of Clinical Pathology 2000; 113: 725-31.

7. Coppell JA, Thalheimer U, Zambruni A, et al. The effects of unfractionated heparin, low molecular weight heparin and danaparoid on the thromboelastogram (TEG): an in-vitro comparison of standard and heparinase-modified TEGs with conventional coagulation assays. Blood Coagulation Fibrinolysis 2006; 17: 97-104.

8. Gerotziafas GT, Chakroun T, Samama MM, Elalamy I. In vitro comparison of the effect of fondaparinux and enoxaparin on whole blood tissue factor-triggered thromboelastography profile. Thrombosis Haemostasis 2004; 92: 1296-302.

The TEG® vs the ROTEM® thromboelastography/thromboelastometry systems

Reply to Kozek-Langenecker et al letter ’Experience with Both Machines.’

Experience with both machines

The TEG^® vs the ROTEM^® thromboelastography/thromboelastometry systems