ROTEM

Question 1

Why ROTEM instead of traditional tests

Answer 1

• Hemostasis: Balance of procoagulant, anticoagulant, fibrinolytic, and cellular components.
  
  • ROTEM uses: Whole blood sample; assesses clot formation and fibrinolysis.
  • Traditional tests (PT/aPTT) assess plasma only, missing cellular elements.
  • ROTEM can:
  • Demonstrate clot formation and breakdown.
  • Detect hypercoagulability, hypocoagulability, and fibrinolysis.
  • Help guide transfusion and hemostatic therapy.

Question 2

ROTEM assays

Answer 2

ROTEM Assays
* INTEM: Activates coagulation via intrinsic pathway (contact activation).
* EXTEM: Activates coagulation via tissue factor (extrinsic).
* HEPTEM: Same as INTEM but with heparinase – neutralizes heparin.
* FIBTEM: Assesses fibrinogen contribution (platelets inhibited).
* APTEM: Modified EXTEM with antifibrinolytic (e.g., aprotinin) – detects hyperfibrinolysis.

Question 3

ROTEM graph parameters

Answer 3

ROTEM Graph Parameters
* CT (Clotting Time): Time until initial clot formation – reflects thrombin generation.

*	CFT (Clot Formation Time): Time from CT to 20 mm amplitude – reflects clot propagation.

*	A10/A20/MCF (Amplitude at 10/20 mins, Max Clot Firmness):
-	Measures clot strength.
-	Reflects platelets, fibrinogen, and factor XIII(Fibrin stabilizing factor)

*	ML (Maximum Lysis): Degree of clot breakdown – indicates fibrinolysis.

* ALPHA Angle-  -It is the tangent to clotting curve from 2mm  -Normal alpha in EXTEM- 60-80 degrees - Normal alpha in INTEM_ 70-80 degrees - low alpha angle indicates slow clot formation- clotting factor def/fibrin def - High alpha angle- hypercoagulability -Reflects speed of fibrinogen accumulation -Provides indication of hyper/hypo coagulable state _Dependent mainly upon Fibrinogen

LY 30
- percentage amplitude reduction 30mins after the maximum amplitude
- A measure of fibrinolysis

Question 4

ROTEM interpretation

Answer 4

• Prolonged CT in INTEM only: Suggests heparin effect.
  
  • Normal HEPTEM + abnormal INTEM: Confirms heparin presence.
  • Reduced A10/MCF in FIBTEM: Suggests low fibrinogen.
  • Normal EXTEM but abnormal APTEM: Suggests fibrinolysis.
  • MCF is usually only higher than A10 by ~10 mm so A10 gives an earlier indication of MCF
  • ML > 15% in EXTEM/FIBTEM: Indicates hyperfibrinolysis.

Question 5

Clinical use

Answer 5

refrence ranges were derived from healthy volunteers hence target range may be higher in acutely bleeding patients.

• Used in bleeding patients to:
  
  • Identify surgical or coagulopathic bleeding.
  • Guide fibrinogen or factor replacement.
    - Monitor antifibrinolytic therapy/response to treatment
  • Reference ranges vary; interpretation should be based on patient’s clinical context.
  • In trauma: A10 in FIBTEM < 7 mm suggests need for fibrinogen replacement but in severe bleeding, value of 18-20 may be req.#(see foot note)
  • CT = thrombin formation,
    
    • A10 = fibrin/platelets, * ML = fibrinolysis.