In an adult with moderate-to-severe ARDS who remains hypoxemic despite low tidal‑volume ventilation (6 mL/kg predicted body weight) and optimized PEEP, what recruitment maneuvers are recommended, including indications, contraindications, technique, and monitoring?

Recruitment Maneuvers in ARDS: Current Recommendations

Prolonged recruitment maneuvers should NOT be routinely used in moderate-to-severe ARDS, as the most recent 2024 American Thoracic Society guidelines now recommend AGAINST their use based on moderate certainty evidence showing no mortality benefit and potential harm. 1

Current Evidence-Based Position

The 2024 ATS guideline represents a significant shift from the 2017 recommendations:

• Strong recommendation AGAINST prolonged lung recruitment maneuvers (LRMs) in moderate-to-severe ARDS (moderate certainty of evidence) 1
• The 2017 guideline had only a conditional recommendation FOR recruitment maneuvers (low certainty of evidence) 2
• This change reflects accumulating evidence that recruitment maneuvers do not improve mortality or morbidity outcomes, which are the priority endpoints 1

What to Do Instead

Use higher PEEP WITHOUT recruitment maneuvers in moderate-to-severe ARDS 1:

• Set PEEP according to disease severity: 10-15 cm H₂O for moderate ARDS, 15-20 cm H₂O for severe ARDS 3
• Maintain lung-protective ventilation: tidal volumes 4-8 mL/kg predicted body weight, plateau pressure ≤30 cm H₂O 1, 2
• For severe ARDS with persistent hypoxemia, implement prone positioning >12 hours/day before considering any recruitment strategies 1, 2

Why the Recommendation Changed

The evidence base reveals important limitations:

• The LOVS trial (2008) showed no mortality difference between an "open lung" strategy (including recruitment maneuvers + high PEEP) versus conventional low tidal volume ventilation, despite improved oxygenation 4
• Recruitment maneuvers improved short-term oxygenation but not survival outcomes 4, 5
• Hemodynamic compromise is a significant risk, particularly in patients with impaired chest wall mechanics or later-stage ARDS 6

Clinical Context Where Recruitment Might Still Be Considered

If you encounter refractory hypoxemia despite optimized management, the evidence suggests:

• Patient selection matters: Recruitment is more likely to work in early ARDS (<7 days) with preserved chest wall mechanics (low chest wall elastance) 6
• Technique if attempted: Stepwise recruitment (incremental PEEP titration) is safer than sustained inflation maneuvers 3
• Monitoring requirements: Continuous hemodynamic monitoring is essential, as cardiac output can drop 31% in non-responders versus 2% in responders 6

Critical Pitfalls to Avoid

• Do not use recruitment maneuvers as a routine oxygenation strategy - the 2024 guidelines explicitly recommend against this practice 1
• Avoid sustained high-pressure inflation (e.g., 40 cm H₂O CPAP for 40 seconds) in patients with chest wall impairment or late ARDS (>7 days), as these patients experience significant hemodynamic compromise without oxygenation benefit 6
• Do not confuse improved oxygenation with improved outcomes - multiple studies show recruitment improves PaO₂/FiO₂ ratios without reducing mortality 4, 5

Alternative Strategies for Refractory Hypoxemia

When hypoxemia persists despite lung-protective ventilation and optimized PEEP:

1. Prone positioning (strong recommendation for severe ARDS) 1, 2
2. Neuromuscular blockade in early severe ARDS (conditional recommendation) 1
3. Corticosteroids (conditional recommendation, moderate certainty) 1
4. VV-ECMO in selected patients with severe ARDS (conditional recommendation, low certainty) 1