How to treat low Maximum Amplitude (MA) on Citrated Fresh Frozen (CFF) Thromboelastography (TEG)?

Treatment of Low Maximum Amplitude (MA) on Citrated Fresh Frozen (CFF) Thromboelastography (TEG)

For patients with low Maximum Amplitude (MA) on CFF TEG, administer fibrinogen concentrate (25-50 mg/kg) as first-line treatment, targeting a fibrinogen level of at least 1.5-2.0 g/L. 1

Understanding Low MA on CFF TEG

• Maximum Amplitude (MA) represents the maximum strength of the clot and primarily reflects platelet function and fibrinogen concentration 1, 2
• Low MA on CFF TEG specifically indicates decreased fibrinogen contribution to clot strength 1
• Normal MA values typically range from 50-70 mm, with values <50 mm indicating significant clot strength impairment 1
• CFF MA values differ from FIBTEM MCF values measured in the same sample, with CFF MA typically reading higher than FIBTEM MCF 3

Diagnostic Approach

• Confirm the low MA finding with conventional laboratory fibrinogen levels (Clauss method) 4
• A CFF amplitude ≤17 mm has high sensitivity (0.74) and specificity (0.97) for detecting Clauss fibrinogen ≤2 g/L 4
• Check for concurrent abnormalities in other TEG parameters that may indicate additional coagulation issues 2

Treatment Algorithm

Step 1: Assess and correct fibrinogen levels

• If CFF MA is low (<20 mm), administer fibrinogen concentrate (25-50 mg/kg) as first-line treatment 1, 5
• Alternative: If fibrinogen concentrate is unavailable, administer 2 pools of cryoprecipitate (equivalent to 4g fibrinogen replacement) 5
• Target fibrinogen level of at least 1.5-2.0 g/L in bleeding patients 5, 1
• Higher fibrinogen targets (>2.0 g/L) may be needed in obstetric hemorrhage 5

Step 2: Assess for additional platelet contribution

• If low MA persists after fibrinogen replacement, consider platelet transfusion 1
• Target platelet count >50,000/mm³ for most bleeding scenarios 1
• Consider higher platelet count targets (>75,000/mm³) for obstetric patients 4

Step 3: Monitor response

• Repeat TEG 15-30 minutes after intervention to assess response 1
• Target MA normalization (typically >50 mm) 1
• If inadequate response, consider additional fibrinogen replacement or platelet transfusion based on laboratory values 1

Special Considerations

• In liver disease patients, TEG may provide more valuable information than standard coagulation tests, as conventional tests may overestimate bleeding risk 6
• In obstetric hemorrhage, a CFF amplitude ≤17 mm strongly correlates with fibrinogen ≤2 g/L 4
• In trauma patients, goal-directed therapy using TEG parameters has been shown to improve outcomes compared to conventional coagulation test-guided therapy 5

Pitfalls to Avoid

• Do not rely solely on conventional coagulation tests (PT, aPTT) as they may not correlate well with TEG parameters 1, 2
• Avoid treating based on isolated laboratory values without considering the clinical context 1
• Remember that anemia can paradoxically show hypercoagulable TEG results due to decreased blood viscosity, potentially masking coagulopathy 5, 2
• Standard TEG is insensitive to antiplatelet agents and cannot reliably detect platelet dysfunction 1, 2
• Be aware of the high variability of TEG measurements (coefficients of variance ranging from 7.1% to 39.9%), which necessitates proper training and regular calibration 5, 2
• Results vary between devices and are not interchangeable between TEG and ROTEM systems 5, 2