How to correct low Maximum Amplitude (MA) on Thromboelastography (TEG)?

Correcting Low Maximum Amplitude (MA) on Thromboelastography (TEG)

To correct low Maximum Amplitude (MA) on TEG, administer platelets for platelet count deficiency and fibrinogen concentrate or cryoprecipitate for fibrinogen deficiency, as these are the primary contributors to clot strength. 1, 2

Understanding Low MA on TEG

• Maximum Amplitude (MA) represents the maximum strength of the clot and primarily reflects platelet function and fibrinogen concentration 2
• Decreased MA suggests thrombocytopenia, platelet dysfunction, or fibrinogen deficiency 2
• Normal MA values typically range from 50-70 mm, with values <50 mm indicating significant clot strength impairment 2
• Early amplitudes (A5 and A10) strongly correlate with MA and can provide faster assessment of clot strength, allowing for earlier intervention 3, 4, 5

Diagnostic Approach

Determine the Specific Cause

• Assess if low MA is primarily due to platelet deficiency or fibrinogen deficiency:
  • Use functional fibrinogen TEG assay to differentiate between platelet and fibrinogen contributions to clot strength 6
  • If functional fibrinogen TEG is unavailable, consider conventional laboratory tests (platelet count and fibrinogen level) to guide therapy 7
• Check for concurrent abnormalities in other TEG parameters that may indicate additional coagulation issues 2

Treatment Algorithm

Step 1: Platelet-Related Interventions

• If platelet count <50,000/mm³ or there is evidence of platelet dysfunction:
  • Administer platelet transfusion (1 adult dose) 7
  • Target platelet count >50,000/mm³ for most bleeding scenarios 7
  • Consider higher platelet count targets (>100,000/mm³) for patients with traumatic brain injury or requiring neurosurgery 7
• For patients on antiplatelet therapy with active bleeding:
  • Administer platelet transfusion regardless of platelet count 7
  • Note that routine use of platelet function devices for monitoring antiplatelet therapy is not recommended 7

Step 2: Fibrinogen-Related Interventions

• If fibrinogen level <1.5-2.0 g/L or functional fibrinogen TEG shows decreased contribution:
  • Administer fibrinogen concentrate (first choice) at 25-50 mg/kg 1
  • If fibrinogen concentrate is unavailable, give cryoprecipitate (1 unit per 10 kg body weight) 1
• Target fibrinogen level of at least 1.5-2.0 g/L in bleeding patients 1

Step 3: Combined Approach for Severe Bleeding

• In cases of massive transfusion or severe bleeding:
  • Consider balanced transfusion approach with RBC:Plasma:Platelets at 1:1:1 ratio 7
  • Continue monitoring TEG parameters to guide ongoing treatment 7

Monitoring Response

• Repeat TEG 15-30 minutes after intervention to assess response 2
• Target MA normalization (typically >50 mm) 2
• Early amplitudes (A5, A10) can be used to predict MA and guide earlier intervention, as they strongly correlate with final MA values 3, 4, 5

Special Considerations

• In liver disease patients, TEG may provide more valuable information than standard coagulation tests 1
• In trauma patients, goal-directed therapy using TEG parameters has been shown to improve outcomes compared to conventional coagulation test-guided therapy 8
• Hyperfibrinolysis (increased LY30 >7.5%) may contribute to decreased MA and is associated with increased mortality in trauma patients 8

Pitfalls to Avoid

• Do not rely solely on conventional coagulation tests (PT, aPTT) as they may not correlate well with TEG parameters 7
• Avoid treating based on isolated laboratory values without considering the clinical context 2
• Remember that anemia can paradoxically show hypercoagulable TEG results due to decreased blood viscosity, potentially masking coagulopathy 2
• Standard TEG is insensitive to antiplatelet agents and cannot reliably detect platelet dysfunction 2