What is ROTEM (Rotational Thromboelastometry) FIBTEM (Fibrin Component Test)?

ROTEM FIBTEM: A Specialized Test for Fibrinogen Assessment

ROTEM FIBTEM is a specialized viscoelastic test that isolates the contribution of fibrinogen to clot formation by eliminating platelet activity through the addition of cytochalasin D, a potent platelet inhibitor. 1

What is ROTEM?

Rotational Thromboelastometry (ROTEM) is a viscoelastic hemostatic assay that provides:

• Real-time graphical and numerical representation of blood clot formation and dissolution
• Assessment of the viscoelastic properties during clot formation and lysis
• Faster results than traditional coagulation tests
• Point-of-care testing capability using whole blood samples

FIBTEM Test Specifically

The FIBTEM test is one of several ROTEM assays with specific characteristics:

• Mechanism: Uses cytochalasin D to inhibit platelet contribution to clot formation 1
• Purpose: Isolates fibrinogen's contribution to clot strength by eliminating platelet effects 1
• Parameters measured:
  • Maximum Clot Firmness (MCF): 9-25 mm reference range in healthy individuals 1, 2
  • Clot Amplitude at 5 minutes (A5) and 10 minutes (A10)
  • Clotting Time (CT)

Clinical Significance and Applications

FIBTEM has several important clinical applications:

1. Assessment of Fibrinogen Function

• Provides functional assessment of fibrinogen contribution to clot formation
• Correlates significantly with fibrinogen levels (r = 0.82, P < .001) 1
• Allows earlier detection of fibrinogen deficiency than standard laboratory tests

2. Guiding Transfusion Therapy

• Used to guide fibrinogen replacement therapy in bleeding patients
• FIBTEM A5 is superior to Clauss fibrinogen in predicting need for massive transfusion 1
• Fibrinogen replacement therapy is recommended at:
  • MCF < 10 mm or A10 < 7 mm in trauma patients 3
  • A5 < 12 mm in postpartum hemorrhage 1

3. Monitoring Pregnancy-Related Coagulation Changes

• Helps assess hypercoagulable state in pregnancy
• MCF values significantly higher in pregnant women compared to non-pregnant women 1
• Useful in managing obstetric hemorrhage with ROTEM-guided transfusion protocols 1

4. Predicting Thromboembolic Complications

• Abnormal FIBTEM parameters may help identify patients at risk for thrombotic events 4
• Particularly useful when combined with other ROTEM tests (EXTEM, INTEM)

Technical Considerations

Important technical aspects to consider when interpreting FIBTEM results:

• Sample stability: Blood samples remain stable for ROTEM analysis for up to 120 minutes 5
• Reproducibility: Coefficient of variation for MCF is <6% 5
• Device variability: Small but significant differences may exist between different ROTEM devices 5
• Limitations: Cannot detect von Willebrand disease or disorders affecting endothelial adhesion 1

Clinical Interpretation

Interpretation of FIBTEM results should consider:

• Low FIBTEM MCF/A5/A10: Indicates fibrinogen deficiency requiring replacement
• Normal FIBTEM with abnormal EXTEM/INTEM: Suggests platelet dysfunction or thrombocytopenia
• High FIBTEM MCF: May indicate hypercoagulable state (e.g., in pregnancy, inflammation)

Limitations

Important limitations to be aware of:

• Cannot assess endothelial contribution to coagulation 1
• May be affected by factor XIII, factor VIII, and von Willebrand factor deficiencies 1
• Hematocrit may influence results 1
• Cannot detect the effects of hypothermia (performed at 37°C) 1
• Not validated for assessing platelet function 1

FIBTEM is a valuable component of the ROTEM panel that provides specific information about fibrinogen's contribution to clot formation, enabling targeted treatment strategies in bleeding patients.