What are the indications, contraindications, and timing for Extracorporeal Membrane Oxygenation (ECMO) initiation?

Indications, Contraindications, and Timing for ECMO Initiation

ECMO should be initiated within 7 days of respiratory failure onset for patients with severe, potentially reversible cardiorespiratory failure when conventional medical therapies have failed or are likely to fail. 1

Types of ECMO and Their Primary Indications

• Venovenous (VV) ECMO is indicated for severe acute respiratory failure with a PaO₂/FiO₂ < 80 mmHg for at least 3 hours despite optimal ventilation, and failure of conventional ventilation strategies and rescue therapies 1, 2
• Venoarterial (VA) ECMO is indicated for patients with severe cardiogenic shock with very low cardiac output and reduced LV ejection fraction, requiring significant inotropic support and/or norepinephrine at dosages >0.5 µg/kg/min 3

Specific Indications for ECMO

• Severe ARDS with PaO₂/FiO₂ < 70 for ≥3 hours or < 100 for ≥6 hours despite optimization of conventional treatments 3
• Refractory hypoxemia unresponsive to conventional management in potentially reversible respiratory failure 2
• pH < 7.25 for at least 3 hours despite optimal conventional therapy 2
• Plateau pressure > 28 cmH₂O for ≥6 hours despite lung-protective ventilation strategies 3
• Evidence of right ventricular overload with pulmonary artery systolic pressure > 40 mmHg and acute cor pulmonale on echocardiography 3

Timing of ECMO Initiation

• Early initiation (within 7 days of respiratory failure onset) is associated with better outcomes 1
• ECMO should be considered before irreversible end-organ damage occurs 1
• Optimization of conventional treatments (low-volume, low-pressure, lung-protective ventilation or prone positioning) should always be undertaken before considering ECMO 3
• Delaying ECMO initiation until after prolonged mechanical ventilation (>9.6 days) is associated with worse outcomes 3

Contraindications for ECMO

• Irreversible cardiopulmonary failure without transplant option 1
• Significant comorbidities that limit life expectancy 1
• Traumatic brain injury is a relative contraindication due to bleeding complications and anticoagulation requirements 4
• Advanced age with multiple comorbidities 1
• Prolonged mechanical ventilation (>7 days) before ECMO consideration 3, 1
• Contraindications to anticoagulation 3
• Irreversible neurological injury 1

Patient Selection Considerations

• Factors supporting ECMO use include:
  • Young age with fewer comorbidities 1
  • Potentially reversible etiology of cardiorespiratory failure 1, 5
  • Failure of conventional therapies despite optimization 2
  • Absence of multi-organ failure 1
• ECMO should be used judiciously as it is a complex, high-risk, and costly modality 1

Institutional Requirements for ECMO Programs

• ECMO should only be performed at centers with sufficient experience, volume, and expertise 1
• Centers caring for more than 20-25 ECMO cases per year have significantly better outcomes 1
• The learning curve to establish competence requires at least 20 cases for optimal results 1
• A multidisciplinary ECMO team should be available 24/7 with quality assurance review procedures 3
• Mobile ECMO teams should be available for retrieval of patients from centers without ECMO capability 1

Emerging Applications and Special Considerations

• "Awake" ECMO (in non-intubated, spontaneously breathing patients) is being explored as an alternative to invasive mechanical ventilation to avoid side effects related to sedation, intubation, and mechanical ventilation 6
• Sequential CRRT (Continuous Renal Replacement Therapy) may be required during ECMO to treat fluid overload, acute kidney injury, and electrolyte disturbances 7
• Hospitals without ECMO capability should establish relationships with ECMO-capable institutions for timely transfer 1

Complications and Pitfalls

• Bleeding complications are common and associated with high mortality rates, particularly intracranial hemorrhage 1
• Acquired von Willebrand Syndrome develops in almost all ECMO patients within hours of device implantation and may contribute to bleeding complications 1
• Thrombotic and thromboembolic complications can occur despite anticoagulation 1
• Evidence supporting ECMO use in some indications remains limited, and further clinical trials are needed 1

Monitoring During ECMO

• Hemodynamic monitoring includes continuous monitoring of arterial blood pressure and ECMO flow 3
• Repeated echocardiography is essential, especially for VA-ECMO 3
• Daily monitoring of fluid balance, central venous oxygen saturation, and lactate levels 3
• Regular assessment for complications including bleeding and thrombosis 3