How do I wean a patient off Extracorporeal Membrane Oxygenation (ECMO)?

ECMO Weaning Protocol

The most effective approach to weaning ECMO requires a systematic, protocol-driven process that gradually reduces extracorporeal support while monitoring for signs of native organ recovery to minimize mortality and morbidity. 1

Pre-Weaning Assessment

Before initiating the weaning process, ensure:

• Clear evidence of improvement in underlying pathology
• Adequate oxygenation parameters
• Acceptable ventilator settings
• Hemodynamic stability
• Resolution of severe acidosis

VV ECMO Weaning Protocol

Step 1: Reduce ECMO Blood Flow Rate (EBFR)

• Decrease by 0.5-1 L/min increments
• Monitor SpO2, hemodynamics, and work of breathing
• Target minimum flow of 2 L/min before considering complete removal
• Allow time between adjustments to assess tolerance

Step 2: Reduce Sweep Gas Flow Rate (SGFR)

• After optimizing EBFR, decrease sweep gas flow in 0.5-1 L/min increments
• Monitor PaCO2 and pH
• This approach utilizes the "decoupling" of oxygenation and decarboxylation possible during extracorporeal support 2

Step 3: Reduce FdO2 on ECMO Circuit

• Decrease the fraction of delivered oxygen on the ECMO circuit
• Target FdO2 of 0.21 (room air) before discontinuation

Step 4: Trial Off Assessment

Consider successful trial when:

• PaO2/FiO2 >150-200 on moderate ventilator settings
• PaCO2 <50 mmHg with acceptable pH (>7.30)
• No significant increase in work of breathing
• Hemodynamic stability
• Acceptable ventilator parameters:
  • FiO2 ≤0.5
  • PEEP ≤10 cmH2O
  • Plateau pressure ≤30 cmH2O

VA ECMO Weaning Protocol

Pre-Weaning Assessment

• Evaluate cardiac recovery through echocardiography
• Look for improved left ventricular ejection fraction (LVEF) - though successful weaning often occurs even with LVEF around 35% 3
• Assess right ventricular function - persistence of RV failure correlates with higher mortality 3
• Monitor pulse pressure - successful weaning shows significant increase in pulse pressure 3

Weaning Steps

1. Gradually reduce ECMO flow rates while monitoring:

   • Hemodynamic stability
   • Pulse pressure
   • Inotropic requirements
   • Echocardiographic parameters

2. Reduce inotropic support to the minimum required (inotropic score around 10) 3

3. Consider the Hoffman clamp technique for precise weaning:

   • Apply Hoffman clamp on the bridge to decrease blood flow beyond idle flow
   • This allows assessment of patient's true potential to successfully come off ECMO 4

Alternative Weaning Approaches

Stand-by Cannula Method

For cases with uncertainty about successful weaning:

• Disconnect patient from the circuit
• Leave cannula in place with heparinized saline maintenance
• Monitor for 12-24 hours before definitive decannulation
• Allows quick reconnection if weaning fails 5

Post-ECMO Care

• Continue lung-protective ventilation strategies
• Gradually wean from mechanical ventilation
• Monitor for bleeding complications related to acquired von Willebrand syndrome (typically resolves within 24-48 hours after ECMO removal) 1
• Maintain vigilant monitoring for respiratory deterioration
• Watch for potential systemic inflammatory response syndrome post-decannulation 6
• Monitor for post-ECMO complications:
  • Deep vein thrombosis
  • Wounds
  • Renal failure
  • Stroke 6

Pitfalls and Caveats

• Avoid early hyperoxia (PaO2 >300 mmHg) as it's associated with mortality and poor neurological outcomes 7
• Target arterial O2 saturation of 92-97% 7
• Prevent rapid decrease in PaCO2 - large peri-cannulation drop in PaCO2 is associated with intracranial hemorrhage and poorer survival 7
• Target PaCO2 between 35-45 mmHg while avoiding rapid changes (>20 mmHg) 7
• Longer ECMO duration and higher transfusion requirements correlate with higher mortality after weaning 3
• Maintain adequate anticoagulation during ECMO support with PTT 1.5-2.5 times control value and anti-FXa level of 0.3-0.7 U/mL 7