What are the indications for Extracorporeal Membrane Oxygenation (ECMO)?

Indications for Extracorporeal Membrane Oxygenation (ECMO)

ECMO is indicated for patients with severe, potentially reversible cardiac or respiratory failure who have failed conventional therapy and are being treated at centers with sufficient experience, volume, and expertise to ensure it is used safely. 1

Types of ECMO and Their Primary Indications

Venovenous (VV) ECMO

VV-ECMO provides respiratory support only and is indicated for:

• Severe acute respiratory failure (ARF) with potentially reversible etiology 1
• Severe ARDS with PaO2/FiO2 < 80 for at least 3 hours despite optimal conventional management 2
• Severe hypercapnic respiratory failure with pH < 7.25 for at least 3 hours 2
• Failure to respond to conventional therapies including:
  • Lung-protective ventilation
  • Higher PEEP
  • Neuromuscular blockade
  • Prone positioning 3

Venoarterial (VA) ECMO

VA-ECMO provides both cardiac and respiratory support and is indicated for:

• Severe refractory cardiogenic shock 4, 5
• Refractory ventricular arrhythmias 4
• Active cardiopulmonary resuscitation for cardiac arrest 4
• Acute or decompensated right heart failure 5
• Post-cardiotomy shock 4, 6
• Post-heart transplant failure 6
• High-risk cardiac catheterization procedures in patients unsuitable for conventional surgery 7

Patient Selection Criteria

ECMO should only be considered when:

1. The underlying condition is potentially reversible
2. The patient has failed conventional management
3. The patient is early in their course of illness
4. There are few risk factors for futility of treatment 3

Contraindications

While specific contraindications vary by institution, common contraindications include:

• Irreversible underlying condition with no potential for recovery
• Conditions incompatible with normal life if the patient recovers
• Preexisting conditions that affect quality of life (severe CNS damage, terminal malignancy)
• Age and size limitations
• Contraindications to anticoagulation 1

Implementation Considerations

Center Requirements

ECMO should be conducted in centers with:

• Sufficient experience (minimum 20 cases per year for the entire center)
• At least 12 ECMO cases for acute respiratory failure per year
• Expertise in therapeutic modalities for severe ARF
• Robust expertise in ventilatory management 1

Team Structure

A multidisciplinary team should guide institutional use of ECMO, including:

• Physicians with ECMO expertise
• Perfusionists or ECMO specialists
• Nurses trained in critical care and ECMO management
• Respiratory therapists
• Surgeons for cannulation 5

Complications to Monitor

1. Bleeding complications (occur in 45-62% of cases):

   • Intracranial hemorrhage (associated with highest mortality)
   • Surgical site bleeding
   • Acquired von Willebrand syndrome (AVWS) develops in almost all ECMO patients within hours of device implantation 1

2. Thrombotic complications (occur in 20-25% of cases):

   • Circuit thrombosis
   • Systemic thromboembolism 1, 4

Fundamental Principles of ECMO Use

1. ECMO is a bridge therapy (not a definitive treatment) to:

   • Recovery
   • A more durable bridge
   • Definitive treatment
   • Decision-making 4

2. ECMO should not be used on unsalvageable patients given its resource-intensive nature 4

3. Patients requiring advanced cardiac support should be transferred to high-volume centers with advanced cardiac capabilities (ventricular assist devices, transplantation) 5

Anticoagulation Management

• Standard protocol: Loading dose of 100 U/kg heparin before cannulation
• Continuous infusion to maintain ACT between 180-220 seconds
• ACT should be checked hourly
• Additional monitoring should include daily:
  • Anti-FXa levels
  • PT, PTT
  • Fibrinogen
  • Platelet count
  • AT III levels 1

Key Pitfalls to Avoid

1. Delayed recognition of ECMO candidates: Early identification of patients who might benefit from ECMO is crucial for optimal outcomes.

2. Relying solely on ACT for anticoagulation management: Multiple laboratory tests are essential for adequate anticoagulation monitoring 1.

3. Overlooking AVWS as a bleeding risk factor: Almost all ECMO patients develop loss of VWF high-molecular-weight multimers within hours of device implantation 1.

4. Widespread use without appropriate expertise: ECMO should be restricted to centers with sufficient experience and volume 1.

5. Using ECMO for patients with irreversible conditions: ECMO should be used only as a bridge to recovery or definitive treatment, not for unsalvageable patients 4.