What investigation best guides transfusion strategy in a patient with profuse intraoperative bleeding during redo coronary artery bypass grafting surgery?

Thromboelastogram is the Best Investigation to Guide Transfusion Strategy During Redo CABG with Profuse Bleeding

Thromboelastogram (TEG) is the most appropriate investigation to guide transfusion strategy in this 78-year-old male chronic smoker with profuse intraoperative bleeding during redo coronary artery bypass grafting surgery. 1

Rationale for TEG in Cardiac Surgery

Viscoelastic testing (TEG/ROTEM) offers significant advantages over conventional coagulation tests in cardiac surgery patients with active bleeding:

1. Rapid assessment of coagulation status: TEG provides real-time information about all phases of coagulation within minutes, allowing for immediate intervention during active bleeding 1

2. Comprehensive evaluation: TEG assesses clot formation, strength, and fibrinolysis, providing a global picture of hemostasis that conventional tests cannot 1

3. Specific guidance for component therapy: TEG identifies specific coagulation defects, allowing targeted blood product administration rather than empiric transfusion 1

4. Evidence-based recommendation: The Association of Anaesthetists guidelines specifically recommend viscoelastic testing for cardiac surgery patients 1

Limitations of Alternative Tests

The other investigations have significant limitations in this scenario:

• Serial hemoglobin monitoring: While useful for tracking overall blood loss, it provides no information about coagulation status or specific factor deficiencies driving the bleeding 1

• Prothrombin time (PT): Standardized for monitoring anticoagulants, not designed for acute hemorrhage; slow turnaround time means results don't reflect the dynamic clinical situation 1

• Arterial blood gas: Provides information about oxygenation and acid-base status but offers minimal guidance for transfusion strategy in coagulopathic bleeding 2

Evidence Supporting TEG in Cardiac Surgery

Multiple studies demonstrate the superiority of TEG-guided transfusion in cardiac surgery:

• A randomized trial of cardiac surgical patients at moderate to high risk of transfusion showed that TEG-guided transfusion resulted in significantly fewer postoperative transfusions, particularly fresh-frozen plasma (4/53 vs 16/52, p<0.002) and platelets (7/53 vs 15/52, p<0.05) 3

• TEG is particularly valuable in this patient who is on dual antiplatelet therapy (aspirin and clopidogrel), as it can identify platelet dysfunction and guide appropriate platelet transfusion 4, 5

• In aortic surgery requiring circulatory arrest, thromboelastometry-guided transfusion significantly reduced allogeneic blood product use (median 9.0 units vs 16.0 units, p=0.02) 6

Clinical Application in This Patient

This patient has several risk factors that make TEG particularly valuable:

1. Dual antiplatelet therapy: The patient is on both aspirin and clopidogrel, which significantly increases bleeding risk during cardiac surgery 5

2. Redo cardiac surgery: Repeat sternotomy increases bleeding risk due to adhesions and more complex dissection

3. Advanced age and comorbidities: Hypertension and diabetes for 20 years may affect coagulation

4. Active, profuse bleeding: Requires rapid assessment and targeted intervention

Implementation of TEG-Guided Transfusion

When implementing TEG-guided transfusion in this patient:

• Use TEG parameters to guide specific blood component therapy:

  • Prolonged R time: Consider fresh frozen plasma
  • Low maximum amplitude (MA): Consider platelet transfusion
  • Low α angle or functional fibrinogen: Consider cryoprecipitate or fibrinogen concentrate
  • Evidence of fibrinolysis: Consider antifibrinolytic therapy

• Target fibrinogen levels should be >1.5 g/L and platelet count >75 × 10⁹/L to ensure adequate clot formation 2

• Repeat TEG testing every 30-60 minutes during active bleeding to monitor response to therapy 2

Conclusion

In a patient with profuse intraoperative bleeding during redo CABG who is on dual antiplatelet therapy, thromboelastogram provides the most comprehensive and timely assessment of coagulation status to guide targeted transfusion therapy. This approach has been shown to reduce unnecessary transfusions and improve outcomes in cardiac surgery patients.