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Standardization of Thromboelastography: a Report from the TEG-ROTEM Working Group

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Standardization of Thromboelastography: a Report from the TEG-ROTEM Working Group Haemophilia (2011), 17, 532–537 DOI: 10.1111/j.1365-2516.2010.02451.x ORIGINAL ARTICLE Laboratory report Standardization of thromboelastography: a report from the TEG-ROTEM working group M. CHITLUR,* B. SORENSEN, G. E. RIVARD,à G. YOUNG,§ J. INGERSLEV,– M. OTHMAN,** D. NUGENT, G. KENET,àà M. ESCOBAR§§ and J. LUSHER–– *Division of Hematology/Oncology, Carman and Ann Adams Department of Pediatrics, Wayne State University/Children’s Hospital of Michigan, Detroit, MI, USA; Haemostasis Research Unit, Centre for Haemostasis & Thrombosis, Guy’s & St Thomas’ NHS Foundation Trust, St Thomas’ Hospital, London, UK; àDivision of Hematology, Hospital Ste Justine, Montreal, QC, Canada; §Department of Hematology/Oncology, Childrens Hospital Los Angeles, Los Angeles, CA, USA; –Center for Hemophilia and Thrombosis, Department of Biochemistry, University Hospital Skejby, Aarhus, Denmark; **Department of Pathology and Molecular Medicine, Queens University, Kingston, ON, Canada; Division of Hematology, Children’s Hospital of Orange County, Orange, CA, USA; ààThrombosis Unit, The National Hemophilia Center, Sheba Medical Center, Tel Hashomer, Israel; §§Gulf States Hemophilia and Thrombophilia Center, University of Texas Health Science Center at Houston, Houston, TX, USA; and ––Hemostasis-Thrombosis Program and Coagulation Labs, Division of Hematology/Oncology, Department of Pediatrics, Marion I. Barnhart Chair in Hemostasis Research, Wayne State University, Children’s Hospital of Michigan, Detroit, MI, USA Summary. Laboratory evaluation of bleeding disorders first international effort at standardization of throm- has been performed with the standard clotting assays boelastography. Both of the instruments using this such as the PT and PTT for several decades. Our technology (TEGÒ and ROTEMÒ) were used. Nine improved understanding of the process of blood laboratories from countries around the globe partici- coagulation has now revealed the important role played pated in this effort. The results showed a significant by the cellular elements such as platelets, monocytes inter-laboratory variance with CV’s greater than 10%. and red blood cells. The need for a test that can assess Although these results were not satisfactory, this clotting in a more ‘global’ manner, beyond the initiation has been the first effort to standardize this methodology of clot formation, has led to greater interest in assays and significant work remains to be done to improve such as thrombin generation and thromboelastography. reliability and reproducibility. These studies were Even though there are several publications using performed on PRP and the results may be more reliable thromboelastography it remains a research tool as the when preformed on whole blood samples. We believe methodology is not standardized. In an attempt to show that it is important to continue this work so that we reproducibility and consistency using thromboelasto- may investigate the usefulness and potential appli- graphy, a group of investigators from different coun- cations of thromboelastography in the evaluation of tries joined hands to form the TEG-ROTEM Working bleeding and thrombosis. Group. Two studies were performed using PRP and FVIII deficient plasma and an intrinsic pathway Keywords: coagulation, consistency, global assays, repro- activator. This article summarizes the results of the ducibility, standardization, thromboelastography Introduction Correspondence: Meera Chitlur, MD, Carman and Ann Adams Department of Pediatrics, Division of Hematology/Oncology, Thromboelastography is a global assay of haemostatic Wayne State University/Children’s Hospital of Michigan, 3901 function, from the beginning of clot formation to the Beaubien Blvd, Detroit, MI 48201, USA. end of fibrinolysis. Two systems utilizing this technol- Tel.: +313 745 5515; fax: +313 745 5237; ogy include Thrombelastograph/TEGÒ (Haemonetics, e-mail: [email protected] Braintree, MA, USA) and ROTEM (Pentapharm Accepted after revision 28 September 2010 GmbH, Munich, Germany). They are simple to use 532 Ó 2011 Blackwell Publishing Ltd STANDARDIZATION OF THROMBOELASTOGRAPHY 533 and proven to be effective methods of intraoperative Even though the parameters are identical there are monitoring to optimize blood product selection and differences in the diagnostic nomenclatures. utilization and have been shown to improve outcomes 1. Coagulation time: R on TEGÒ and CT on during complex surgical procedures such as cardiotho- ROTEMÒ. racic surgery and liver transplantation [1,2]. Case 2. Clot Formation time: K on TEGÒ and CFT on reports or small case series have addressed the useful- ROTEMÒ. ness of thromboelastography in the management of 3. Maximum Clot Firmness: MA on TEGÒ and MCF bleeding or monitoring of treatment with bypassing on ROTEMÒ agents [3,4]. In order to establish the usefulness of this 4. Shear Elastic Modulus Strength: G on both instru- test a standardized methodology needs to be developed ments. and reproducibility and consistency have to be demon- 5. a/Angle-Rate of polymerization of clot: a on both strated. In an attempt to initiate this process, the TEG- instruments. ROTEM Working group was established in 2006 and While there are several other parameters available on investigators from several countries joined hands to both instruments to measure other parameters of perform these studies. Herein we present the results of coagulation and clot lysis, the above represent the the first international study, wherein nine laboratories common parameters used to assess coagulation. from six countries (Canada, Denmark, Israel, Norway, Since the TEGÒ and ROTEMÒ are similar yet not UK and USA) participated. identical, the objective of our efforts was to determine if the same instrument could produce similar results when under similar conditions, thereby proving repro- Materials and methods ducibility and consistency. We did not intend to Ò The main components of the thromboelastograph con- compare between the two instruments, TEG and Ò sist of a cylindrical cup and a pin. In the TEGÒ the cup ROTEM . is oscillated through an angle of 4°45¢ over a 10 s In order to assess the reproducibility of the throm- Ò interval, while in the ROTEMÒ, the pin oscillates and boelastographic parameters on both the TEG and Ò the cup remains stationary. The torque of the cup is ROTEM two sets of experiments were conducted transmitted to the pin through sample viscosity in the using the initiator for the intrinsic pathway provided by cup. Unclotted blood transmits little or no torque from the manufacturers of the instruments (Kaolin/Intem) cup to pin. As the blood clots, fibrin fibres form between first with platelet rich plasma (PRP) and in the second the cup and pin, transferring a portion of the cup’s experiment both normal pooled plasma and factor VIII motion to the pin. With clot lysis the torque decreases. (FVIII) deficient plasma were evaluated. The object of The computerized system automatically records kinetic this study was to establish consistency and reproduc- changes in the whole blood sample. The clots physical ibility between laboratories using the same method on properties, such as the rate of clot formation, the the same instrument. strength and stability of the clot are thereby recorded by In order to ensure that the instruments were in good the system, and are dependent on the interaction of the working order it was determined that the date of the last coagulation factors, platelets and fibrinogen. The trac- maintenance check was within 6 months of running the ing produced is called the thromboelastogram as shown test. in Fig. 1. Since PRP is more stable during storage and trans- The TEGÒ and ROTEMÒ although similar have portation, this was determined to be the sample of minor differences in the mechanical aspects. This is choice. A pool of normal as well as FVIII deficient represented in Table 1. plasma was provided by Center for Hemophilia and Fig. 1. The thromboelastography trace. Ó 2011 Blackwell Publishing Ltd Haemophilia (2011), 17, 532–537 534 M. CHITLUR et al. Table 1. Characteristics of the TEGÒ and ROTEMÒ. TEG ROTEM Two channels Four channels A pin connected with a torsion wire, is inserted into the sample. The pin (sensor) is fixed on the tip of a rotating shaft which is guided by a ball Sample cup oscillates bearing system. The shaft rotates back and forth. Sample cup is stationary Mixing of the contents in the sample cup is done with the oscillation of Mixing of the contents in the cup is accomplished by re-aspirating into the the cup over the pin. automated pipette. Activators used: Activators used: KAOLIN: Vial coated with kaolin to which 1 mL INTEM: Partial thromboplastin phospholipids made from rabbit brain. Blood is blood per plasma is added. Volume sufficient to run two channels not mixed outside the cup therefore only 400 lL required per test. Sample volume: 360 lL Sample volume: 340 lL Thrombosis, Aarhus University Hospital, Skejby, Den- plasma was transferred to ROTEM cup already con- mark (Ingerslev & Sorensen). Although whole blood is taining 20 lL InTEM and 20 lL starTEM (buffered, the sample of choice for these assays, this was a specifically concentrated calcium chloride solution sup- limitation that was foreseen. plied by manufacturer) and recording was initiated. Method: Intrinsic activation was evaluated using Temperature was maintained at 37°C during the testing. standard reagents (Same lot number) provided by the Electronic pipette was preferred to be used for all runs. manufacturers: Kaolin from Haemoscope and InTEM If manual pipetting was used, reverse pipetting was from Pentapharm. Samples were run using the same recommended. All attempts were made to minimize the protocol as recommended for whole blood by the appearance of bubbles in the sample cup and all tests manufacturer. were run for a minimum of 60 min. The above For the TEGÒ: Each aliquot of plasma was thawed procedure was repeated twice with the same ROTEMÒ for 10 min in a water bath at 37°C. One mL of the equipment on three different days for a total of 24 plasma was then transferred to the kaolin vial and recordings/instrument of 60 min. mixed by inverting it five times.
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