This document discusses point-of-care coagulation testing (POCCT) using viscoelastic devices. It describes several devices used for POCCT including thromboelastography (TEG), rotational thromboelastometry (ROTEM), and sonoclot analysis. The document outlines the principles and interpretation of these tests as well as their purported benefits over standard coagulation tests. It discusses the need for rapid POCCT in managing coagulopathic bleeding in situations like trauma, transplantation, and cardiac surgery. The literature on using POCCT in trauma and obstetrics is also briefly mentioned.

1. VISCOELASTIC POINT OF
CARE TESTING
Dr Charul Jakhwal
MBBS, MD Anesthesiology, PDCC-
CCM
12th May 2023

2. CONTENT
Introduction to POCT -
Principles
Interpretation and Treatment
Literature
Need? Devices? Advantages ?

3. Point Of Care Testing (POCT)
Medical diagnostic testing at (or near) the point of care.

4. POCT CAN BE PERFORMED:
• ON SITE,
• IN THE OPERATING ROOM, AND
• IN THE ICU

5. POCT- NEED:
• LIMITATIONS OF CENTRAL LABORATORIES TO TIMELY AND COMPLETELY PROVIDE
RESULTS TO CLINICIANS FOR THE DIAGNOSIS AND MANAGEMENT OF COAGULOPATHIC
BLEEDING ASSOCIATED WITH CARDIAC SURGERY, LIVER TRANSPLANTATION,AND
TRAUMA BEYOND STANDARD COAGULATION TESTS (PT/APTT, PLATELET COUNT, AND
FIBRINOGEN LEVEL)

6. COMMONLY USED POINT-OF CARE DEVICES
• THROMBOELASTOGRAPHY (TEG),
• ROTATION THROMBOELASTOMETRY (ROTEM),
• SONOCLOT ANALYSIS.

8. PURPORTED BENEFITS OVER STANDARD TESTS
• Measures whole blood, not just plasma
• Looks at clot generation and propagation beyond the
point of clot appearance
• Allows comment on clot ‘quality’
• Can identify fibrinolysis
FAST –potential information on clotting status within 5mins
of test starting

9. PRINCIPLES

10. POINT OF CARE COAGULATION TESTING
(POCCT)
Viscoelastic properties of whole blood clot
Thromboelastography = Thromboelastometry
(TEG) (ROTEM)
(TEG; Haemonetics
Corporation, Braintree, MA, USA)
(Rotemw; Tem International
GmbH, Munich, Germany)

11. VISCOELASTICITY

14. HARDWARE

15. TEG DEVICE
• 360 UL OF WHOLE BLOOD IS ADDED TO ACTIVATORS IN TWO DISPOSABLE HEATED (37’C)
CUPS.
• A PIN ATTACHED TO A TORSION WIRE IS IMMERSED INTO THE BLOOD AND THE CUP
ROTATES THROUGH 4.45 DEGREE IN EITHER DIRECTION, EACH ROTATION LASTING 10 S.
(TF OR KAOLIN)
• THE PIN INITIALLY REMAINS STATIONARY GENERATING A STRAIGHT LINE ON THE
TRACING, BUT AS THE BLOOD CLOTS, THE ROTATIONAL MOVEMENT OF THE CUP IS
TRANSMITTED TO THE PIN. A MECHANICAL– ELECTRICAL TRANSDUCER CONVERTS THE
TORSION ON THE PIN INTO THE CHARACTERISTIC TEG TRACING FROM WHICH A
NUMBER OF PARAMETERS ARE DERIVED.

16. THE ROTEM ANALYSER
• THE ROTEM ANALYSER USES A MODIFICATION OF THIS TECHNOLOGY;
• 300 UL OF WHOLE BLOOD WITH ACTIVATORS IS INCUBATED IN A DISPOSABLE CUVETTE
(FOUR PARALLEL CHANNELS) AND PLACED IN A HEATED (37 DEGREE C) HOLDER.
• A PIN FIXED ON A STEEL AXIS STABILIZED BY A BALL BEARING IS IMMERSED INTO THE
BLOOD. A SPRING ROTATES THE PIN IN EITHER DIRECTION WHILE THE CUVETTE STAYS
STATIONARY. THE INITIAL UNRESTRICTED ROTATION OF THE PIN STARTS TO
ENCOUNTER INCREASING IMPEDANCE AS THE CLOT STRENGTH INCREASES. THIS IS
DETECTED BY AN OPTICAL SYSTEM CONSISTING OF A LIGHT-EMITTING DIODE, A MIRROR
ON THE STEEL AXIS, AND AN ELECTRONIC CAMERA, AND IS TRANSLATED INTO THE
CHARACTERISTIC TRACING FROM WHICH AGAIN VARIOUS PARAMETERS ARE DERIVED.

17. Rotational thrmboelastometer, ROTEM® (Pentapharm, GmbH, Munich, Germany) offers four important assays—
EXTEM, INTEM, FIBTEM, and APTEM—to assess different aspects of hemostasis and coagulation pathways.
1.EXTEM assay: In this assay, activity of extrinsic pathway of coagulation is explored by using tissue factor to
activate the coagulation cascade. (thrombin formation/ platelet function / fibrinogen)
2.INTEM assay: In this assay, unlike EXTEM, activity of the intrinsic pathway is explored and contact activator,
ellagic acid (INTEM) is used to activate the coagulation process. INTEM assay is used to evaluate effect of heparin
and of protamine.
3.FIBTEM assay: In this assay, cytochalasin D is added to the whole blood sample along with the tissue factor. The
cytochalasin D inhibits platelet aggregation. *entirely reflective of fibrinogen content
4.APTEM: It uses aprotinin or tranexamic acid in addition to tissue factor and provides information regarding the
effect of antifibrinolytic drugs.

18. SONOCLOT ANALYZER
• THE SONOCLOT SIMILARLY MEASURES THE DEVELOPMENT OF CLOT VISCOELASTIC
STRENGTH. THE PRINCIPLE OF FUNCTION IS BASED ON A VERTICALLY MOVING PISTON.
• THE DEVICE MEASURES THE IMPEDANCE TO VIBRATION AT THE TIP OF THE PROBE.
INFORMATION PROVIDED INCLUDES FUNCTION OF COAGULATION, FIBRIN GEL
FORMATION, CLOT RETRACTION (PLATELET FUNCTION), AND FIBRINOLYSIS.
• THE SONOCLOT ANALYZER GENERATES BOTH A QUALITATIVE GRAPH (SONOCLOT
SIGNATURE) AND QUANTITATIVE RESULTS ON THE CLOT FORMATION TIME (ACT—
ONSET) AND RATE OF FIBRIN POLYMERIZATION (CLOT RATE)

20. INTERPRETATIONS

23. • CLOT INITIATION OCCURS IN RESPONSE TO SHEAR STRESS. THE TIME TAKEN TO
INITIATE A CLOT (REACTION TIME OR CLOTTING TIME) IS PRIMARILY DEPENDENT ON
CLOTTING FACTORS.
• CLOTTING FACTOR DEFICIENCIES OR THE PRESENCE OF INHIBITORS SUCH AS HEPARIN.
• EARLY DISSEMINATED INTRAVASCULAR COAGULATION (DIC).
• CLOT FORMATION (K TIME, CLOT FORMATION TIME, A-ANGLE) IS PRIMARILY DEPENDENT
ON FIBRINOGEN POLYMERISATION AND, TO SOME DEGREE, PLATELET AGGREGATION.
• HYPOFIBRINOGENAEMIA OR THROMBOCYTOPENIA.
• HYPERFIBRINOGENAEMIA OR EARLY DIC.
• CLOT STABILITY (MAXIMUM AMPLITUDE, MAXIMUM CLOT FIRMNESS) IS A PRODUCT OF
PLATELET NUMBER AND FUNCTION, AND, TO A LESSER EXTENT, FIBRIN STRENGTH.
• REDUCED STABILITY SUGGESTS IMPAIRED PLATELET FUNCTION, THROMBOCYTOPENIA, OR
HYPOFIBRINOGENAEMIA.
• EXCESSIVE STABILITY, ON THE OTHER HAND, SUGGESTS THROMBOCYTOSIS OR HYPERFIBRINOGENAEMIA.
• CLOT DEGENERATION (LYSIS 30 MINUTES AFTER MAXIMUM AMPLITUDE) IS AN
INDICATION OF FIBRINOLYSIS.
• DEGENERATION MAY BE ACCELERATED IN STATES OF HYPERFIBRINOLYSIS, SUCH AS TISSUE PLASMINOGEN
ACTIVATOR RELEASE.

26. POINT-OF-CARE COAGULATION TESTING
TEG
ROTEM
SONOCLOT
PLATELET FUNCTION ANALYZER (PFA-100) (SIEMENS, DEERFIELD, IL, USA)
PLATELETWORKS (HELENA LABORATORIES, BEAUMONT, TX, USA)
THE VERIFYNOW SYSTEM (ACCUMETRICS, SAN DIEGO, CA, USA)
THE MULTIPLATE DEVICE (DYNABYTE, MUNICH, GERMANY)
CLOTTING FACTOR TESTS; POCCT FOR PT, APTT, AND INR
HEPARIN TESTS; ACT

27. LITERATURE

31. TRAUMA

32. http://www.c4ts.qmul.ac.uk/bleeding-and-
coalgulation/itactic (Accessed on 9/10/16)

33. OBSTETRICS

34. OBSTETRICS

35. SUMMARY
• Viscoelastic, POCCT devices offer the prospect of rapid assessment and
rational, individually tailored transfusion therapy in the management of major
haemorrhage.
• Barriers remain to their effective and efficient use, and in many areas a
protocolised transfusion strategy may still produce the best outcomes overall.
• Evidence of effectiveness is lacking still, but it is difficult to imagine these devices
will not be more widely used in the near future.

36. THANK YOU