teg_5000_user_manual_ver_4-2-3.pdf
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TEG® 5000 Thrombelastograph®
Hemostasis System
User Manual
TEG Analytical Software (TAS) Version 4.2.3
For TEG® Analytical Software (TAS) Version 4.3 users, please
refer to the Addendum section of the User Manual for detailed
instructions for using the new software features.
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Technical Support:
Contact your local service representative, or the main office at:
Haemoscope Corporation
Niles IL 60714 USA
800-GET-A-TEG / 800-438-2834
847-588-0453
Fax: 847-588-0455
Web: www.haemoscope.com
E-mail: info@haemoscope.com
Copyright ©1999-2007 by Haemoscope Corporation.
All rights reserved. No part of the contents of this book may be reproduced or transmitted in any form or by any means without the written permission of Haemoscope
Corporation.
Thrombelastograph® and TEG® are registered trademarks, and TAS™, Guide™, and
PlateletMapping™ are trademarks of Haemoscope Corporation. Other products mentioned are trademarks of their respective companies.
End of Life - The life cycle of the TEG analyzer is seven years. Please do not discard
or recycle. Contact your Haemoscope representative for information about sending
your machine back to Haemoscope for proper disposal.
INDICATIONS FOR USE
The TEG system is a non-invasive diagnostic instrument designed to monitor and analyze the
hemostasis state of a blood sample in order to assist in the assessment of patient clinical
hemostasis conditions. The TEG system is indicated for use with adult patients where an evaluation of their blood hemostasis properties is desired. Hemostasis evaluations are commonly used
to assess clinical conditions such as post-operative hemorrhage and/or thrombosis during and
following cardiovascular surgery, organ transplantation, trauma, and cardiology procedures.
INTENDED USE
The TEG system is intended to be used in vitro to provide a quantitative and qualitative indication of the hemostasis state of a blood sample by monitoring, measuring, analyzing and reporting hemostasis parameter information. The TEG analyzer records the kinetic changes in a
sample of whole blood, plasma or platelet rich-plasma as the sample clots, retracts and/or lyses
(breaks apart).
Results from the TEG analyzer should not be the sole basis for a patient diagnosis; TEG results
should be considered along with a clinical assessment of the patient’s condition and other coagulation laboratory tests. The TEG analyzer is for Professional Use Only.
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Table of Contents
1
n
TEG® Design and Principles of Operation . . . . . . . 1
TEG® Parameters . . . . . . . . . . . . . . . . . . 4
R or R-Time . . . . . . . . . . . . . . . . 5
K or K-time . . . . . . . . . . . . . . . . . 5
Angle (a) . . . . . . . . . . . . . . . . . . 5
MA . . . . . . . . . . . . . . . . . . . . . 5
Other clot formation parameters . . . . . . . . . . 6
PMA . . . . . . . . . . . . . . . . . . . . 6
Time to MA. . . . . . . . . . . . . . . . . 6
A parameter . . . . . . . . . . . . . . . . 6
G parameter . . . . . . . . . . . . . . . . 6
E parameter . . . . . . . . . . . . . . . . 7
Thrombodynamic Potential Index . . . . . 7
The Coagulation Index. . . . . . . . . . . . . . . . 7
Clot Lysis Parameters . . . . . . . . . . . . . . . . 8
LY30 and LY60 . . . . . . . . . . . . . . . 8
A30 and A60 . . . . . . . . . . . . . . . . 8
Estimated Percent Lysis . . . . . . . . . . 10
Clot Lysis Time . . . . . . . . . . . . . . 10
Lysis Time Estimate . . . . . . . . . . . . 10
Velocity (First Derivative) Parameters . . . . . . . . . . . . . . 10
Blood Sample Types . . . . . . . . . . . . . . . . . . . . . . . 11
Native Whole Blood Coagulation Samples . . . . . 11
Modified Native Whole Blood Samples . . . . . . . 12
Activators . . . . . . . . . . . . . . . . . 12
Heparin Neutralizers . . . . . . . . . . . 12
Platelet Blockers . . . . . . . . . . . . . 13
TEG® 5000 User Manual
Copyright © 1999-2007 Haemoscope Corp.
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Chapter :
Antifibrinolytic Drugs . . . . . . . . . . . 13
Sodium-Citrated Whole Blood Samples . . . . . . 13
Data Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Qualitative Analysis . . . . . . . . . . . . . . . . . . . . . . . 14
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
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Hemostasis . . . . . . . . . . . . . . . . . . . . 17
Components of Hemostasis . . . . . . . . . . . . . . . . . . . 17
Tools for the Clinician . . . . . . . . . . . . . . . 17
Functional Hemostasis . . . . . . . . . . . . . . . 18
The resulting clot. . . . . . . . . . . . . . . . . . 18
Stabilizing the fibrin network structure . . . . . . 19
Platelet contractility force . . . . . . . . . . . . . 19
The clot as a mechanical device . . . . . . . . . . 19
Interrelationship of Parameters . . . . . . . . . . . . . . . . . 19
An example. . . . . . . . . . . . . . . . . . . . . 21
TEG® Runs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Differential Diagnosis (Simultaneous Runs) . . . . 22
Tracing Analysis Exercises . . . . . . . . . . . . . 24
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
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Introducing the TEG® Software . . . . . . . . . . . 27
"Case" Management . . . . . . . . . . . . . . . . . . . . . . . 31
Input and Selection . . . . . . . . . . . . . . . . . . . . . . . 31
Touch screens . . . . . . . . . . . . . . . . . . . 31
Barcode scanning. . . . . . . . . . . . . . . . . . 32
Previous version databases . . . . . . . . . . . . . . . . . . . . 32
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Copyright © 1999-2007 Haemoscope Corp.
TEG® 5000 User Manual
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Remote Version
4
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Looking at TEG® Data . . . . . . . . . . . . . . . 35
Logging in . . . . . . . . . . . . . . . . . . . . . 36
User name . . . . . . . . . . . . . . . . 37
Database selection . . . . . . . . . . . . 37
Overview . . . . . . . . . . . . . . . . . 40
Local toolbar . . . . . . . . . . . . . . . 40
Numeric data panel . . . . . . . . . . . . 40
Scrolling . . . . . . . . . . . . . . . . . 40
No tracing available. . . . . . . . . . . . 40
* symbol . . . . . . . . . . . . . . . . . 41
¶ symbol . . . . . . . . . . . . . . . . . 41
§ symbol . . . . . . . . . . . . . . . . . 41
Colors . . . . . . . . . . . . . . . . . . . 41
Sorting . . . . . . . . . . . . . . . . . . 42
Patient filter . . . . . . . . . . . . . . . . . . . . 43
Site filter . . . . . . . . . . . . . . . . . . . . . . 43
Active filter . . . . . . . . . . . . . . . . . . . . . 44
Data/Tracing Views . . . . . . . . . . . . . . . . . . . . . . . 44
Select a sample . . . . . . . . . . . . . . . . . . . 44
Maximized view . . . . . . . . . . . . . . . . . . 45
The clot graphic. . . . . . . . . . . . . . 46
Reference tracing . . . . . . . . . . . . . 47
Set Reference . . . . . . . . . . . . . . . . . . 47
View Reference . . . . . . . . . . . . . . . . . 48
Normal tracing . . . . . . . . . . . . . . 48
Save Normal . . . . . . . . . . . . . . . . . . . 48
View Normal . . . . . . . . . . . . . . . . . . . 49
Normal and Reference tracings together . 49
TEG® 5000 User Manual
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Chapter :
Multiple maximized tracings . . . . . . . 50
Special multi view . . . . . . . . . . . . 52
Guide™. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Adding Notes. . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Patient notes . . . . . . . . . . . . . . . . . . . . 56
Sample notes . . . . . . . . . . . . . . . . . . . . 57
Printing Reports . . . . . . . . . . . . . . . . . . . . . . . . . 58
“Instant” print . . . . . . . . . . . . . . . . . . . 59
Quick report . . . . . . . . . . . . . . . . . . . . 59
Full report . . . . . . . . . . . . . . . . . . . . . 60
Report options . . . . . . . . . . . . . . . . . . . 61
CPT codes . . . . . . . . . . . . . . . . . 62
Patient summary . . . . . . . . . . . . . . . . . . 62
Patient listings . . . . . . . . . . . . . . . . . . . 62
Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Undo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Exiting the Program . . . . . . . . . . . . . . . . . . . . . . . 64
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More Views of TEG® Data . . . . . . . . . . . . . 65
Detail view . . . . . . . . . . . . . . . . . . . . . 65
Tracing Detail . . . . . . . . . . . . . . . 66
View clot . . . . . . . . . . . . . . . . . . . . . 66
Enter other test data . . . . . . . . . . . . . . . 66
Reference and normal tracings. . . . . . . . . . 67
Sample Detail . . . . . . . . . . . . . . . 67
Notes Detail . . . . . . . . . . . . . . . . 68
The Status Bar . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Advanced Filters . . . . . . . . . . . . . . . . . . . . . . . . . 69
By selected criteria . . . . . . . . . . . . . . . . . 69
Case Management . . . . . . . . . . . . . . . . . . . . . . . . 71
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TEG® 5000 User Manual
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Procedure . . . . . . . . . . . . . . . . . . . . . 72
Rx . . . . . . . . . . . . . . . . . . . . . . . . . 73
Blood products . . . . . . . . . . . . . . . . . . . 74
Notes . . . . . . . . . . . . . . . . . . . . . . . . 74
Other . . . . . . . . . . . . . . . . . . . . . . . . 75
Locking . . . . . . . . . . . . . . . . . . . . . . . 75
Clinicians . . . . . . . . . . . . . . . . . . . . . . 75
Clusters. . . . . . . . . . . . . . . . . . . . . . . 75
Samples . . . . . . . . . . . . . . . . . . . . . . 76
Case summary report. . . . . . . . . . . . . . . . 76
Numerical data summary . . . . . . . . . 78
Trend graphs . . . . . . . . . . . . . . . 79
TEG tracings . . . . . . . . . . . . . . . 81
Printing selected pages . . . . . . . . . . 81
Using TEG® Tracings with Other Software . . . . . . . . . . . 81
The Coagulopathy
Library (Guide) . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Add a tracing to the library. . . . . . . . . . . . . 83
Modify a library entry . . . . . . . . . . . . . . . 85
Delete a library entry . . . . . . . . . . . . . . . . 85
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Database Records . . . . . . . . . . . . . . . . . 87
Creating a case/patient. . . . . . . . . . . . . . . 87
Creating a record . . . . . . . . . . . . . . . . . . 88
Deleting patients . . . . . . . . . . . . . . . . . . 88
Deleting records . . . . . . . . . . . . . . . . . . 89
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Database operations . . . . . . . . . . . . . . . . 91
Importing V2 databases . . . . . . . . . . . . . . . . . . . . . 96
V2 databases without PX files . . . . . . . . . . . 97
TEG® 5000 User Manual
Copyright © 1999-2007 Haemoscope Corp.
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Chapter :
Sample type updates . . . . . . . . . . . . . . . . 97
Importing V1 or V2 databases . . . . . . . . . . . . . . . . . . 97
Importing V3 databases . . . . . . . . . . . . . . . . . . . . . 97
Exporting TEG® data . . . . . . . . . . . . . . . . . . . . . . 98
eConsult . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Defining eConsult options. . . . . . . . . . . . . 103
Backing Up TEG® Data. . . . . . . . . . . . . . . . . . . . . 103
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Using Export Files . . . . . . . . . . . . . . . . 105
Creating the export file . . . . . . . . . . . . . . 106
Importing into Excel . . . . . . . . . . . . . . . 106
Importing into Access . . . . . . . . . . . . . . . 108
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User Profiles . . . . . . . . . . . . . . . . . . . 113
Login preferences . . . . . . . . . . . . . . . . . 114
Setting up tests . . . . . . . . . . . . . . . . . . 115
Setting up normal values . . . . . . . . . . . . . 116
Setting up software options . . . . . . . . . . . . 118
Setting video options . . . . . . . . . . . . . . . 119
TEG-Enabled Version
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Daily Operation. . . . . . . . . . . . . . . . . . 125
Set Up for Daily Use . . . . . . . . . . . . . . . . . . . . . . 125
Loading Cups and Pins . . . . . . . . . . . . . . . . . . . . . 126
Ending the run . . . . . . . . . . . . . . . . . . . . . . . . . 129
Setting the Temperature . . . . . . . . . . . . . 129
Hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
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Copyright © 1999-2007 Haemoscope Corp.
TEG® 5000 User Manual
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Biohazards . . . . . . . . . . . . . . . . . . . . 131
TEG® surfaces . . . . . . . . . . . . . . . . . . 131
Physical hazards . . . . . . . . . . . . . . . . . 132
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Sample Preparation . . . . . . . . . . . . . . . 133
Native TEG® Samples . . . . . . . . . . . . . . . 133
Materials. . . . . . . . . . . . . . . . . 133
Procedure . . . . . . . . . . . . . . . . 134
Modified Native TEG® Samples . . . . . . . . . . 134
Materials. . . . . . . . . . . . . . . . . 134
Reagent in treated cup format . . . . . . 135
Reagent in vial format . . . . . . . . . . 135
Summary . . . . . . . . . . . . . . . . 135
Citrated Whole Blood TEG® samples . . . . . . . 135
Materials. . . . . . . . . . . . . . . . . 135
Procedure . . . . . . . . . . . . . . . . 135
Quality Control . . . . . . . . . . . . . . . . . . . . . . . . . 136
References . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
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Running Samples. . . . . . . . . . . . . . . . . 139
Logging in. . . . . . . . . . . . . . . . . . . . . 141
Database selection . . . . . . . . . . . . 142
Login Preferences . . . . . . . . . . . . . . . . . 144
Operator ID . . . . . . . . . . . . . . . . . . . . 145
TEG screen . . . . . . . . . . . . . . . . . . . . 145
Inputting Sample Identifying Information . . . . 147
Sample type . . . . . . . . . . . . . . . 148
Patient name . . . . . . . . . . . . . . 148
Scanning Patient ID. . . . . . . . . . . . . . . 148
TEG® 5000 User Manual
Copyright © 1999-2007 Haemoscope Corp.
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Chapter :
Sample description . . . . . . . . . . . 149
Entering sample ID data
for QC samples . . . . . . . . . . . . . . . . . . 149
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Quality Assurance . . . . . . . . . . . . . . . . 155
Maintenance and function checks . . . . . . . . . 156
Mechanical . . . . . . . . . . . . . . . 156
Electronic . . . . . . . . . . . . . . . . 156
Electronics Testing (eTest) . . . . . . . 157
Maintenance history reporting . . . . . . . . . 159
Operational . . . . . . . . . . . . . . . 159
Documentation . . . . . . . . . . . . . 159
Calibration and calibration verification . . . . . . 159
Control procedures . . . . . . . . . . . . . . . . 160
Biological control output . . . . . . . . 160
Use of approved accessories and consumables . . 161
Quality Control Samples/Databases . . . . . . . . . . . . . . 161
Normal ranges . . . . . . . . . . . . . . . . . . 163
Quality Assurance Reports . . . . . . . . . . . . . . . . . . . 163
Lot number history . . . . . . . . . . . 164
Levey-Jennings report . . . . . . . . . . 164
Daily maintenance log . . . . . . . . . . 165
Service history . . . . . . . . . . . . . . 165
Viewing the QC database . . . . . . . . . . . . . . . . . . . . 165
Local normal ranges . . . . . . . . . . . . . . . . . . . . . . 166
Quality assurance summary. . . . . . . . . . . . . . . . . . . 166
Operational checks & maintenance guidelines . . . . . . . . . 166
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User Profiles for Operators . . . . . . . . . . . . 169
Setting up sample types . . . . . . . . . . . . . . 169
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TEG® 5000 User Manual
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Include . . . . . . . . . . . . . . . . . 170
Sample type order . . . . . . . . . . . . 170
Setting software options . . . . . . . . . . . . . 170
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Specifications and Performance Characteristics . . 173
Performance Characteristics . . . . . . . . . . . . . . . . . . 174
Accuracy . . . . . . . . . . . . . . . . . . . . . 174
Precision . . . . . . . . . . . . . . . . . . . . . 176
Sensitivity & Specificity . . . . . . . . . . . . . . 177
Normal Ranges . . . . . . . . . . . . . . . . . . 177
Functional Fibrinogen Level Test . . . . . . . . . 178
Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Sensitivity factors . . . . . . . . . . . . . . . . . 181
Interference factors . . . . . . . . . . . . . . . . 181
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TEG® Analyzer Setup and Installation . . . . . . . 183
Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Positioning the
Analyzer . . . . . . . . . . . . . . . . . . 184
Leveling the TEG® Analyzer. . . . . . . . . . . . . . . . . . . 185
Software Installation . . . . . . . . . . . . . . . . . . . . . . 185
Channel Activation . . . . . . . . . . . . . . . . 185
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Special Sample Type Handling . . . . . . . . . . . 187
Functional Fibrinogen Level . . . . . . . . . . . . . . . . . . . . . 187
GPIIb/IIIa Inhibitor-treated (FF) Samples. . . . . 187
In the Tracing Screen . . . . . . . . . . 187
In the Multiple Tracing Screen . . . . . 187
In Interpretation . . . . . . . . . . . . . 188
TEG® 5000 User Manual
Copyright © 1999-2007 Haemoscope Corp.
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Chapter :
PlateletMapping™ . . . . . . . . . . . . . . . . . . . . . . . 188
D
n
Troubleshooting . . . . . . . . . . . . . . . . . 191
Login . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Maintenance . . . . . . . . . . . . . . . . . . . . . . 193
Loading the cups and pins. . . . . . . . . . . . . . . . 194
Biological Controls . . . . . . . . . . . . . . . . . . . 194
Unexpected tracing results . . . . . . . . . . . . . . . 195
Running Samples . . . . . . . . . . . . . . . . . . . . 196
Temperature controller . . . . . . . . . . . . . . . . . 198
Normal ranges. . . . . . . . . . . . . . . . . . . . . . 198
Ejecting the cup and pin. . . . . . . . . . . . . . . . . 198
Remote Access . . . . . . . . . . . . . . . . . . . . . 199
Printing . . . . . . . . . . . . . . . . . . . . . . . . . 200
Database . . . . . . . . . . . . . . . . . . . . . . . . 201
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Copyright © 1999-2007 Haemoscope Corp.
TEG® 5000 User Manual
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TEG® 5000 User Manual
Copyright © 1999-2007 Haemoscope Corp.
Page xi
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TEG® Design and Principles of Operation
Chapter
1
TEG® Design and Principles of Operation
T
he Thrombelastograph® (TEG®) Hemostasis System 5000 series is a
non-invasive diagnostic instrument designed to monitor and analyze the coagulation state of a blood sample in order to assist in the assessment of patient
clinical hemostasis conditions. The TEG® analyzer is indicated for use with
adult patients where an evaluation of their blood coagulation properties is desired. Coagulation evaluations are commonly used to assess clinical conditions
such as post-operative hemorrhage and/or thrombosis during and following
cardiovascular surgery, organ transplantation, trauma, and cardiology procedures.
Indications for Use
The TEG® 5000 series analyzer is intended to be used to provide a quantitative and qualitative indication of the coagulation state of a blood sample by
monitoring, measuring, analyzing, and reporting coagulation parameter information. The TEG® analyzer records the kinetic changes in a sample of whole
blood, plasma or platelet rich-plasma as the sample clots, retracts, and/or
lyses (breaks apart).
Intended Use
Results from the TEG® analyzer should not be the sole basis for a patient diagnosis; TEG® results should be considered along with a clinical assessment of
the patient’s condition and other coagulation laboratory tests. For Professional
Use Only.
Introduction
This manual describes how to use the Thrombelastograph (TEG )
Hemostasis System 5000 series and higher using Version 4 TEG Analytical
Software (TAS™).
®
®
Application of the TEG® analyzer has been described in articles published in
many of the most prestigious peer-reviewed journals. All suggested treatments
are based on the experiences of clinicians who have used them successfully
and published their results. References are found at the end of each chapter.
This introduction outlines some of the various analytical techniques that can
provide additional information on a blood sample. Most of the techniques
TEG® 5000 User Manual
Copyright © 1999-2007 Haemoscope Corp.
Page 1
Page 18
Chapter 1: TEG® Design and Principles of Operation
have evolved from over 1000 research publications in the last 20 - 30 years,
with the greatest increase in applications occurring in the last five years. The
most outstanding results have been demonstrated for the management of
hemostasis during major surgical interventions such as liver transplants and
cardiopulmonary bypass procedures. Concomitantly, recent advances in the
understanding of the biochemistry of coagulation have supported the advantages of whole blood TEG® analysis by demonstrating the role of cell surfaces
in localization, amplification, and modulation of coagulation functions 1. As a
result of this knowledge, the TEG® analyzer has evolved from a research tool
into a powerful clinical monitor to evaluate the interaction of platelets and
plasma factors, plus any additional effects of other cellular elements (e.g.,
WBCs, RBCs, etc.) with the activities of the plasma factors.
The discussion of the techniques will be centered around their current application to liver transplantation and cardiopulmonary bypass. The most commonly used sample types and techniques and their advantages are listed later
in table 1 on page 11.
The TEG® system is comprised of the TEG® Hemostasis System together with
the TEG® Analytical Software. This package provides breakthrough capabilities such as simultaneous analysis of up to eight samples, automatic calculation of a wide range of coagulation parameters, and data management
facilities. The software can be run in a configuration that allows the analyzer
to be placed in a centralized location such as a laboratory, with results displayed where needed, for example, in remote operating rooms. A full description of the TEG® Analytical Software can be found beginning in Chapter 4.
TEG® Design
Principles
Page 2
The TEG® analyzer’s approach to the monitoring of patient hemostasis is based
on these two facts:
1. The end result of the hemostasis process is a single product — the clot.
2. The clot's physical properties (rate, strength, and stability) will determine
whether the patient will have normal hemostasis, will hemorrhage or will
develop thrombosis.
Copyright © 1999-2007 Haemoscope Corp.
TEG® 5000 User Manual
Page 19
TEG® Design and Principles of Operation
Figure 1.1. TEG® sample cup design
The TEG® analyzer measures the clot’s physical property by the use of a special stationary cylindrical cup that holds the blood and is oscillated through an
angle of 4°45´ (Figure 1.1). Each rotation cycle lasts 10 seconds. A pin is suspended in the blood by a torsion wire and is monitored for motion. The torque
of the rotating cup is transmitted to the immersed pin only after fibrin-platelet
bonding has linked the cup and pin together. The strength of these fibrin-platelet bonds affects the magnitude of the pin motion, such that strong
clots move the pin directly in phase with the cup motion. Thus, the magnitude of the output is directly related to the strength of the formed clot. As the
clot retracts or lyses, these bonds are broken and the transfer of cup motion is
diminished.
The rotation movement of the pin is converted by a mechanical-electrical
transducer to an electrical signal which can be monitored by a computer.
The resulting hemostasis profile is a measure of the time it takes for the first
fibrin strand to be formed, the kinetics of clot formation, the strength of the
clot (in shear elasticity units of dyn/cm2) and dissolution of clot (Figure 1.2).
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Figure 1.2. TEG® tracing parameters
Performance
Characteristics and
Specifications
Performance characteristics and specifications for the TEG® analyzer are detailed in Appendix A.
TEG® Theory
The computerized Thrombelastograph® Hemostasis System (TEG®) automatically records the kinetic changes in a sample of whole blood, plasma, or
platelet-rich-plasma as the sample clots, retracts and/or lyses (breaks apart).
The resultant coagulation profile is therefore a measure of the kinetics of clot
formation and dissolution and of clot quality.
The TEG® analyzer monitors shear elasticity, a physical property of a blood
clot, and is, therefore, sensitive to all the interacting cellular and plasmatic
components in the blood that affect the rate or structure of a clotting sample
and its breakdown. The clot’s ability to perform useful mechanical work (the
work of hemostasis) is a function of the net result of the interactive coagulation proteins and cellular elements involved in the process of hemostasis. In
essence, the TEG® analyzer measures the ability of the clot to perform mechanical work throughout its structural development.
The overall coagulation profile can be qualitatively or quantitatively interpreted in terms of the hypo-, normal, or hypercoagulable state of the sample
and the degree of lysis.
TEG® Parameters
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To evaluate the graphic information displayed by the TEG® analyzer, five
main parameters of clot formation and lysis are measured (See Figure 1.2):
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R
R time is the period of time of latency from the time that the blood was placed in the
TEG® analyzer until the initial fibrin formation. This represents the enzymatic portion of
coagulation.
K
K time is a measure of the speed to reach a certain level of clot strength. This represents clot kinetics.
a
a measures the rapidity of fibrin build-up and cross-linking (clot strengthening). This
represents fibrinogen level.
MA
MA, or Maximum Amplitude, is a direct function of the maximum dynamic properties of
fibrin and platelet bonding via GPIIb/IIIa and represents the ultimate strength of the fibrin clot. This represents platelet function/aggregation.
LY30
LY30 measures the rate of amplitude reduction 30 minutes after MA. This represents
clot lysis.
The four coagulation parameters R, K, a, MA) can be combined to yield indices of coagulability, while additional measurements can be made to evaluate
other aspects of the coagulation profile such as time to MA and time to lysis as
described below.
Reaction Time. The time from the start of a sample run until the first significant levels of detectable clot formation (amplitude = 2mm in the TEG® tracing). This is the point at which most traditional coagulation assays reach their
end-points. R-time is prolonged by anticoagulants and factor deficiencies and
shortened by hypercoagulable conditions.
R or R-Time
Achievement of a certain clot firmness. The time from the measurement of R
(beginning of clot formation) until a fixed level of clot firmness is reached
(amplitude = 20 mm). Therefore, K-time is a measure of the speed or clot kinetics to reach a certain level of clot strength. K is shortened by increased
fibrinogen level and, to a lesser extent, by platelet function, and is prolonged
by anticoagulants that affect both. If the amplitude does not reach 20mm, K is
undefined. If the MA of the sample is less than 25 mm, do not use K for clinical decisions. In these samples, use angle.
K or K-time
The kinetics of clot development. The angle is closely related to K-time, since
they both are a function of the rate of polymerization. The angle is more comprehensive than K-time, since there are hypocoagulable conditions in which
the final level of clot firmness does not reach an amplitude of 20 mm (in
which case K is undefined). Similar to K, a is larger by increased fibrinogen
levels and, to a lesser extent, by platelet function, and is decreased by anticoagulants that affect both.
Angle (a)
Maximum Amplitude. Measurement of maximum strength or stiffness (maximum shear modulus) of the developed clot. Clot strength is the result of two
MA
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components — the modest contribution of fibrin to clot strength and the much
more significant contribution of the platelets.
Other clot formation
parameters
In addition to the major parameters just described, several others can aid in
determining clot kinetics, strength, and stability:
p projection of MA expressed as the PMA parameter
p time to MA expressed as the TMA parameter
p amplitude, clot strength at a specific time expressed as the A parameter
p shear elastic modulus strength expressed as the G and E parameters
p thrombodynamic index expressed as the TPI parameter
Additional coagulation parameters describing thrombus formation expressed as velocity (first derivative) parameters are discussed below in
the section named “Velocity (First Derivative) Parameters” on page 11.
PMA
PMA - Projected MA, an estimator of MA, that is, whether the MA value will
achieve at least the lower limit of the normal value for samples treated with
Kaolin or Celite (see the section named “Blood sample types” later in this
chapter). PMA facilitates earlier detection of platelet dysfunction and earlier
therapy decisions before MA is available.
PMA begins to display when amplitude reaches 5 mm, and is finalized when
the rate of clot formation slows (a is final). PMA is displayed as either:
p 0 (to indicate that it is likely that MA will reach the lower limit of normal)
p 1 (MA is unlikely to reach the lower limit of normal).
Once the MA value approaches the lower limit of normal, it should be used for
evaluation instead of PMA.
Time to MA
TMA - Time to MA, a global measurement of the dynamics of clot kinetics.
TMA combines the rate of clot development from the start of a sample run until the clot reaches its maximum strength. This can be described as the time
needed to form a stable clot.
A parameter
The A parameter measures the width of the tracing at the latest time point. It
is equal to MA until MA is determined. Amplitude (A) is a function of clot
strength or elasticity and is measured in mm.
G parameter
The A parameter can be transformed into the actual measure of clot strength
(G) (shear elastic modulus strength, SEMS) and is measured in dyn/cm2 divided by 1000 (displayed in the software as Kd/sc). The absolute SEMS of the
sample can be calculated from A as follows:
G = (5000A/(100-A))/1000
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Note that A is equal to MA until MA is reached, at which time calculation of G
stops. The elastic shear modus G of the sample increases exponentially in proportion to the amplitude (A) of the TEG® tracing.
An amplitude of 50 mm (normal value of whole blood) corresponds to a
SEMS of 5000 dyn/cm2. An increase in A from 50mm to 67 mm is equivalent
to a two-fold increase in the SEMS. Thus, the G parameter not only provides a
measurement of clot firmness in force units, but also is more indicative of
small changes in the clot strength or clot breakdown than is the amplitude in
mm because it is an exponential reflection of A.
E is a normalized G parameter and is referred to as an elasticity constant. In
the formula, 5000A is replaced with 100A. (Note that A is equal to MA until
MA is reached.) The rationale behind this index is that at the amplitude of 50
mm (normal value of whole blood), the E is (100*50)/(100-50) = 100.
Therefore E provides a relative elastic scale in which a normal clot with a
maximum elastic modulus of 50 mm is given an elastic modulus of 100. E is
expressed as dyn/cm2.
E parameter
TPI=EMX / K, relative elastic shear modulus divided by the kinetics of clot development, where EMX is E at maximum amplitude (MA), i.e.,
EMX = (100*MA)/(100-MA), and K is measured in mm. This parameter was
proposed by Raby2,3. According to Raby3, TPI describes the patient’s global coagulation whether the patient is normal coagulable (TPI between 6 - 15),
hypocoagulable (TPI < 6), or hypercoagulable (TPI >15), when using sodium
citrated native whole blood. The utility of this parameter is demonstrated by
Szefner et al3 and Copeland et al4 in the monitoring of the hemostasis of patients undergoing total artificial heart or heart assist device implantation.
Thrombodynamic Potential
Index
A Coagulation Index (CI) that describes the patient’s overall coagulation is
derived from the R, K, MA and Angle (a) of native or kaolin/celite-activated
whole blood tracings.
The Coagulation Index
Normal values for the Coagulation Index lie between -3.0 and +3.0, which is
equivalent to three standard deviations about the mean of zero.
Positive values outside this range (CI > +3.0) indicate that the sample is hypercoagulable, whereas negative values outside this range (CI < -3.0) indicate
that the sample is hypocoagulable.
Hypercoagulable conditions like cancer (adenoma) or monitoring deep-vein
thrombosis are detected at CI values of +5.0 and above8,9.
Preliminary equations involving whole blood, celite- or kaolin-activated whole
blood, or both combined are available7,8. The equations should be validated
before applying them clinically. Since the normal range of sodium citrated
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blood is very similar to non-citrated blood, the same coefficients are applied to
sodium citrated native and celite blood as best estimates.
The equation for the TEG® coagulation indices are simple linear combinations
of the variables as follows:
Index
Equation
Native Whole Blood
CI = - 0.2454R + 0.0184K + 0.1655MA - 0.0241a -5.0220
Celite-activated WB
CI = -0.6516Rc - 0.3772Kc + 0.1224MAc + 0.0759ac -7.7922
Combined
CI = - 0.112R - 0.222K + 0.040MA -0.042a - 0.578Rc + 0.370Kc
+ 0.111MAc + 0.097ac -8.397
Note: R and K values must be in min. Parameters that have the subscript “c”
are measured for Celite-activated samples. Also note: when MA < 20 mm, K
is undefined and CI is not calculated.
Cohen et al7 compared TPI with CI in a study involving cancer patients, and
found that the CI is very close to TPI, but is a slightly better discriminator between hyper- and normal coagulable in this population. This is perhaps due to
the contribution of the R and a parameters in the CI equation.
Clot Lysis Parameters
Several methods have been proposed to evaluate clot lysis.
It should be noted that a clinical fibrinolytic state involves the presence of tissue plasminogen activator (t-PA), which produces fibrin degradation products.
Characteristically, fibrinolysis leads to clot dissolution, depending on the severity and stage (early or late) of the fibrinolytic process. Therefore, several
sets of parameters are computed to quantify the fibrinolytic state. They are
similar in that they rely on the loss of clot strength with time after the maximum clot strength (MA) is reached:
p reduction in area measurements expressed as the LY30 and LY60
parameters
p reduction in amplitude measurements expressed as A30 and A60
parameters
p estimated percent lysis expressed as the EPL parameter
p clot lysis time expressed as the CLT parameter
LY30 and LY60
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The LY30 and LY60 parameters measure percent lysis at 30 minutes and 60
minutes after MA is reached. The LY30 and LY60 measurements are based on
the reduction of the area under the TEG® tracing from the time MA is measured until 30 (or 60) minutes after the MA.
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The A30 and A60 parameters are the amplitudes of the TEG® tracing at 30
minutes and 60 minutes after MA is measured.
A30 and A60
A30 and A60 are point measurements that look only at the TEG® tracing amplitude A at 30 and 60 minutes after MA. LY30 and LY60, on the other hand,
are measures of the area under the TEG® tracing, and, therefore, contain more
information because they look at the entire tracing between MA and 30 (or
60) minutes after MA.
A30 and A60 are sometimes presented in an alternate form called the Whole
Blood Clot Lysis Index (CL30 or CL60), which presents the values of A30 or
A60 relative to MA. The formulas are:
CL30 = 100 x (A30 / MA)
CL60 = 100 x (A60 / MA)
The smaller the value of CL30 or CL60, the greater the severity of the
fibrinolytic process. Note that CL30 and CL60 measure fibrinolysis inversely to
the way it is measured by the LY30 and LY60 parameters. Generally, when
LY30 and LY60 are high (i.e., fibrinolytic activity is high), CL30 and CL60 are
low, and vice versa.
You can convert CL30 or CL60 to be proportional to the level of fibrinolytic
activity with the formula:
CL30´ = 100 – CL30 = 100 x (MA – A30) / MA
CL60´ = 100 – CL60 = 100 x (MA – A60) / MA
The two TEG® tracings in Figure 1.3 illustrate the significance of the LY parameters relative to the CL parameters:
MA
30 min
Figure 1.3. CL30 parameter
Thirty minutes after MA is reached, the amplitudes of both tracings read zero
due to fibrinolytic activity. Therefore, using the formulas on the previous
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page, the CL30 parameter for both tracings is zero. In this instance, the CL30
parameter is of no use in differentiating the two tracings.
However, the LY30 parameters for the two tracings are radically different. In
the top tracing, the shaded area under the curve is approximately 15% of the
rectangular area. (The rectangle represents the area under the curve if there
had been no fibrinolysis.). Thus, LY30 is approximately 85%. In the bottom
tracing, the shaded area comprises about 85% of the rectangle. This makes
the value of LY30 approximately 15%.
Thus, CL30 and CL60 represent point measurements of the fibrinolytic status
at exactly 30 and 60 minutes after MA is achieved. LY30 and LY60 represent
the fibrinolytic process that took place during those 30 or 60 minutes.
The lysis parameters are illustrated in Figures 1.2 and 1.3
Estimated Percent Lysis
Estimated Percent Lysis (EPL) is the estimated percent lysis at 30 minutes after MA. This parameter is computed 30 seconds after the MA, and is continually updated until 30 minutes after MA is reached, when EPL becomes equal
to LY30. This parameter gives an idea of the percent lysis prior to 30 minutes
after MA. EPL is computed by finding the slope connecting MA to any point
between MA and 30 minutes after, then extrapolating to A30. EPL is then
100(MA-Â30)/MA, until A30 is reached and it becomes equal to LY30.
Clot Lysis Time
Clot Lysis Time (CLT) is the elapsed time between MA and 2 mm amplitude
or less post MA.
Lysis Time Estimate
Lysis Time Estimate (LTE) is an estimate of CLT. It is computed 30 seconds after MA and is continually updated until 60 minutes after MA or when an amplitude is reached, whichever comes first. If LTE is greater than three hours,
the value is displayed as ">3 hrs." LTE is derived by calculating the slope of
the tracing and extrapolating to an amplitude of 2 mm.
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Velocity (First Derivative) Parameters
A set of parameters are also generated from the mathematical first derivative
of the standard TEG tracing. These parameters describe the formation of the
thrombus, as well as the lysis of the thrombus.
Parameter
Definition
TMRTG
Time to maximum rate of thrombus generation
MRTG
Maximum rate of thrombus generation
TG
Total thrombus generated
TMRL
Time to maximum rate of lysis
MRL
Maximum rate of lysis
L
Total lysis
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Blood Sample Types
Blood Sample Types
The following sections describe the various sample preparations that can be
used with the TEG® analyzer and the conditions under which to use the different blood modifiers. The actual sample preparation for analysis is described in
Chapter 11.
Table I
Sample Type
Blood/Reagent
Purpose
Native
Native whole blood (NWB)
Global evaluation of coagulation
Activated
NWB & Celite, TF, Kaolin,
Thrombin, DAPTTIN, etc.
Speed analysis
Antifibrinolytic
drugs
WB & eACA, Aprotinin, Tx
Reverse fibrinolysis
Heparinase
WB & Heparinase
Reverse heparin effects
Citrated
Citrated WB (CWB)
Prolonged storage
Activated citrated
CWB & Celite, Kaolin, TF,
Thrombin, DAPTTIN, etc.
Speed analysis
PRP
Citrated Platelet Rich Plasma
Enriched platelet function
PPP
Citrated Platelet Poor Plasma
Plasma coagulation
Platelet blockers
WB & ReoPro, Integrilin,
Aggrastat, etc.
Reduced or abrogated platelet function
Native Whole Blood
Coagulation Samples
In general, the basic TEG® measurements of kinetics, strength and stability of
a coagulum can be determined by using a native whole blood sample. This
method has provided the most sensitive method for monitoring
hypercoagulation or fibrinolytic conditions.
This type of sensitivity does not mean this sample type is the most practical,
and we will see how more practical techniques can provide similar results.
Modified Native Whole
Blood Samples
Native whole blood samples can be modified by addition of reagents to the in
vitro sample to determine if a possible therapy might be effective for a
coagulopathy, to improve speed of analysis, or to reverse a clinical condition
(e.g., heparinization).
These techniques involve addition of the following reagents to the native
whole blood sample:
p Activators (Kaolin, Celite, tissue factor, thrombin, DAPTTIN, etc.)
p Heparin neutralizers (Heparinase, protamine)
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