What recruitment techniques should be tried in severe Acute Respiratory Distress Syndrome (ARDS) prior to Extracorporeal Membrane Oxygenation (ECMO) consideration?

Recruitment Techniques for Severe ARDS Prior to ECMO Consideration

Before considering ECMO in severe ARDS, a sequential approach of lung-protective ventilation strategies, higher PEEP, recruitment maneuvers, prone positioning, and neuromuscular blockade should be implemented to optimize oxygenation and ventilation.

Initial Lung-Protective Ventilation Strategy

• Set low tidal volumes of 4-8 mL/kg predicted body weight 1
• Maintain plateau pressure ≤30 cmH₂O 2
• Calculate predicted body weight (PBW) as:
  • Males: 50 + 0.91 × [height (cm) - 152.4] kg
  • Females: 45.5 + 0.91 × [height (cm) - 152.4] kg 1
• Monitor and minimize driving pressure (Plateau pressure - PEEP) 1

PEEP Optimization

• For moderate to severe ARDS, use higher PEEP levels (typically 15-20 cmH₂O for severe ARDS) 2, 1
• Titrate PEEP based on oxygenation response and respiratory system compliance 1
• Consider PEEP titration using decremental PEEP after recruitment 3
• Target SpO₂ 88-92% when PEEP ≥10 cmH₂O 1

Recruitment Maneuvers

• For severe ARDS with refractory hypoxemia, perform recruitment maneuvers 2, 4
• Preferred recruitment maneuver techniques:
  • Brief application of continuous positive airway pressure (30-40 cmH₂O) 1
  • Progressive incremental increases in PEEP at constant driving pressure 1, 5
  • Stepwise recruitment with pressure-controlled ventilation (PCV) using plateau pressure/PEEP of up to 40-45/25 cmH₂O 4, 6
• Avoid prolonged recruitment maneuvers with PEEP >35 cmH₂O for >60 seconds 2, 1
• Assess recruitment success by improvement in oxygenation and compliance 5

Prone Positioning

• Implement prone positioning for patients with PaO₂/FiO₂ ratio <150 mmHg 2, 1
• Maintain prone position for 16-20 hours per day 1
• Continue prone positioning for at least 48 hours or until significant improvement in oxygenation 2

Neuromuscular Blockade

• Use neuromuscular blocking agents for ≤48 hours in patients with severe ARDS (PaO₂/FiO₂ ratio <150 mmHg) 2
• Consider neuromuscular blockade for:
  • Persistent ventilator dyssynchrony
  • Prevention of excessive transpulmonary pressure
  • Facilitation of lung-protective ventilation 1

Conservative Fluid Management

• Implement a conservative fluid strategy for patients with established ARDS who do not have evidence of tissue hypoperfusion 2, 1
• Balance fluid administration to maintain adequate organ perfusion while minimizing pulmonary edema 1

ECMO Consideration

• Consider VV-ECMO in selected patients with severe ARDS when the above strategies fail 2
• Typical indications for ECMO consideration:
  • Persistent hypoxemia despite optimized conventional therapy
  • PaO₂/FiO₂ ratio <80 mmHg despite optimal recruitment strategies
  • Unmanageable respiratory acidosis
  • High plateau pressures despite lung-protective ventilation 2

Common Pitfalls and Caveats

• Avoid excessive PEEP that may cause hemodynamic compromise or barotrauma
• Monitor for pneumothorax during and after recruitment maneuvers
• Ensure adequate sedation before implementing recruitment maneuvers or prone positioning
• Remember that recruitment potential varies among patients with ARDS 6, 3
• Assess response to each intervention before proceeding to more invasive strategies
• Recognize that not all patients will respond to recruitment maneuvers, particularly those with late-phase ARDS 6, 7

This algorithmic approach ensures that all evidence-based lung recruitment strategies are systematically attempted before considering the more resource-intensive and invasive option of ECMO for severe ARDS.