What is the best approach for a recruitment manoeuvre in a critically ill patient with acute respiratory distress syndrome (ARDS) or severe respiratory failure, possibly with underlying conditions like chronic obstructive pulmonary disease (COPD) or heart disease, requiring mechanical ventilation?

Recruitment Maneuvers in ARDS

For adult patients with moderate to severe ARDS, recruitment maneuvers should be performed as they reduce mortality, improve oxygenation, and decrease the need for rescue therapies, though clinicians must exercise caution in patients with hemodynamic instability or hypovolemia. 1

Evidence-Based Recommendation

The American Thoracic Society/European Society of Intensive Care Medicine/Society of Critical Care Medicine guidelines conditionally recommend that adult patients with ARDS receive recruitment maneuvers, based on moderate-quality evidence showing mortality reduction. 1 This recommendation is strengthened by meta-analysis of six randomized trials (1,423 patients total) demonstrating:

• Significant mortality reduction (RR 0.81; 95% CI 0.69-0.95) 1, 2
• Improved oxygenation at 24 hours (mean increase of 52 mm Hg PaO2/FiO2) 1, 2
• Reduced need for rescue therapy (RR 0.64; 95% CI 0.35-0.93) 1
• No increased barotrauma risk (RR 0.84; 95% CI 0.46-1.55) 1, 2

When to Perform Recruitment Maneuvers

Target patients with moderate to severe ARDS (PaO2/FiO2 < 200 mmHg) who are receiving lung-protective ventilation with low tidal volumes (4-8 ml/kg predicted body weight). 1, 3

Recruitment maneuvers should be performed before PEEP selection to optimize subsequent PEEP titration, as RMs and PEEP are interdependent for successful ventilatory management. 1, 4

Types of Recruitment Maneuvers

The guidelines acknowledge multiple RM techniques, though no single method has been definitively proven superior: 1

• Sustained inflation: Continuous positive airway pressure of 30-40 cm H2O for 40 seconds 1, 5
• Stepwise PEEP increases: Progressive incremental increases in PEEP at constant driving pressure 1, 6
• High driving pressure maneuvers: Brief application of high inspiratory pressures 1

The stepwise approach may allow for individualized titration but requires careful monitoring as it can produce heterogeneous responses with potential adverse effects. 6

Critical Safety Considerations

Hemodynamic monitoring is mandatory during recruitment maneuvers, as transient hypotension occurs in a subset of patients. 1 The guidelines specifically warn against performing RMs in patients with preexisting hypovolemia. 1

Monitor for these complications during the maneuver: 1, 6

• Transient hypotension (RR 1.30 for hemodynamic compromise, though not statistically significant)
• Transient hypoxemia during the procedure itself
• Decreased respiratory system compliance in some patients (indicating potential overdistension)

The procedure should be discontinued immediately if severe hemodynamic compromise occurs. 6

Integration with Overall ARDS Management

Recruitment maneuvers must be combined with a comprehensive lung-protective strategy: 1, 3

• Maintain low tidal volumes (4-8 ml/kg PBW) with plateau pressure ≤30 cm H2O 1, 3
• Apply higher PEEP (typically 10-15 cm H2O for moderate-severe ARDS) after recruitment 1, 3
• Consider prone positioning for >12 hours daily if severe ARDS (PaO2/FiO2 <150 mmHg) persists 1, 3

The evidence suggests that recruitment maneuvers work synergistically with higher PEEP strategies—five of six trials showing mortality benefit used higher PEEP as a co-intervention. 1, 2

Contraindications and Cautions

Do not perform recruitment maneuvers in patients with: 1, 6

• Hemodynamic instability or active hypovolemia
• Severe cardiovascular disease with limited hemodynamic reserve
• Recent pneumothorax or significant air leak
• Elevated intracranial pressure (relative contraindication)

Monitoring Response

After performing a recruitment maneuver, assess: 6, 5

• Oxygenation improvement: Expect PaO2/FiO2 increase within 24 hours 1
• Respiratory mechanics: Monitor for improved compliance (indicates successful recruitment) vs. decreased compliance (suggests overdistension) 6
• Hemodynamic stability: Ensure blood pressure returns to baseline 6
• Sustained benefit: PEEP must be titrated appropriately to maintain recruited lung units 5, 4

Common Pitfalls

Failing to maintain adequate PEEP after recruitment is the most critical error—recruited alveoli will collapse without sufficient end-expiratory pressure. 5, 4 Set PEEP at least 2 cm H2O above the level where oxygenation begins to decline. 6

Applying aggressive recruitment in patients with focal ARDS may cause harm, as these patients have less recruitable lung and higher risk of overdistension. 1 Recent evidence suggests that nonfocal ARDS patterns respond better to recruitment strategies. 1

Delaying recruitment until late ARDS reduces effectiveness—recruitment maneuvers are most beneficial in early ARDS when lung tissue remains recruitable. 7, 5