How to correct a low angle on a Thromboelastography (TEG)?

Correcting Low Alpha Angle on Thromboelastography (TEG)

To correct a low alpha angle on TEG, administer fibrinogen replacement using either fibrinogen concentrate (25-50 mg/kg) or cryoprecipitate (1-2 pools), as the alpha angle primarily reflects the rate of fibrin formation and is most strongly influenced by fibrinogen levels. 1, 2

Understanding Alpha Angle on TEG

• Alpha angle represents the speed of clot formation and is primarily influenced by fibrinogen concentration and function 1
• Normal alpha angle values typically range from 53-72 degrees, with lower values indicating slower clot formation 1
• Decreased alpha angle suggests impaired fibrinogen function or deficiency 1

Diagnostic Approach

• Confirm the low alpha angle finding with a functional fibrinogen TEG if available 2
• Consider conventional laboratory testing for fibrinogen levels to guide replacement therapy 3
• Check for concurrent abnormalities in other TEG parameters that may indicate additional coagulation issues 1

Treatment Algorithm

• For mild to moderate reduction in alpha angle:

  • Administer fibrinogen concentrate (first choice) at 25-50 mg/kg 2, 3
  • Alternative: 1 pool of cryoprecipitate (contains approximately 2g of fibrinogen) 2

• For severe reduction in alpha angle:

  • Administer fibrinogen concentrate at 50-60 mg/kg 2
  • Alternative: 2 pools of cryoprecipitate 2

• Target fibrinogen level of at least 1.5-2.0 g/L in bleeding patients 2, 3

• Higher fibrinogen targets (>2.0 g/L) may be needed in obstetric hemorrhage 3

Monitoring Response

• Repeat TEG 15-30 minutes after intervention to assess response 3
• Target alpha angle normalization (typically >53 degrees) 1
• If response is inadequate, consider additional fibrinogen replacement 2

Special Considerations

Liver Disease

• Patients with cirrhosis often have rebalanced hemostasis despite abnormal conventional coagulation tests 4
• TEG-guided blood product transfusion has been shown to decrease transfusion requirements compared to standard care in liver disease 2
• Target fibrinogen levels may need to be higher (≥2.0 g/L) in liver disease patients 2

Trauma

• In trauma patients with bleeding, TEG-guided resuscitation has demonstrated improved outcomes compared to conventional testing 5
• For trauma patients, consider a threshold of alpha angle <67 degrees for fibrinogen replacement 5

Pitfalls to Avoid

• Anemia can paradoxically show hypercoagulable TEG results due to decreased blood viscosity, potentially masking coagulopathy 4
• High variability of TEG measurements (coefficients of variance ranging from 7.1% to 39.9%) necessitates proper training and regular calibration 4
• Results vary between devices and are not interchangeable between TEG and ROTEM systems 4
• TEG is performed at 37°C and cannot assess effects of hypothermia on coagulation 4
• Do not rely solely on conventional coagulation tests (PT, aPTT) as they may not correlate well with TEG parameters 4

Efficacy of TEG-Guided Therapy

• TEG-guided transfusion strategies have been shown to result in fewer blood transfusions compared to conventional coagulation test-guided strategies 2, 6
• Goal-directed therapy using TEG parameters allows for more targeted correction of specific coagulation defects 2
• In trauma patients, TEG-guided resuscitation has demonstrated lower mortality at 24 hours and 30 days compared to conventional testing 2