What is the recommended mechanical ventilation (MECVENT) strategy for patients with respiratory failure, including those with Acute Respiratory Distress Syndrome (ARDS) and Chronic Obstructive Pulmonary Disease (COPD)?

Mechanical Ventilation Strategy for Respiratory Failure

Core Lung-Protective Ventilation (All ARDS Patients)

For all patients with ARDS, implement lung-protective ventilation with tidal volumes of 4-8 mL/kg predicted body weight (targeting 6 mL/kg) and maintain plateau pressures strictly below 30 cmH₂O. 1, 2

Tidal Volume Calculation and Targets

• Calculate predicted body weight (PBW) using: males = 50 + 0.91 × [height (cm) - 152.4] kg; females = 45.5 + 0.91 × [height (cm) - 152.4] kg 1, 2
• Set initial tidal volume at 6 mL/kg PBW, with acceptable range of 4-8 mL/kg PBW 1, 2
• Measure plateau pressure in all ARDS patients and maintain upper limit ≤30 cmH₂O 1, 2
• Accept permissive hypercapnia (pH >7.20) as a necessary consequence of lung protection—do not sacrifice low tidal volumes to normalize blood gases 2, 3

PEEP Strategy: Titrate to ARDS Severity

For moderate-to-severe ARDS (PaO₂/FiO₂ <200 mmHg), use higher PEEP levels (typically >10 cmH₂O); for mild ARDS (PaO₂/FiO₂ 200-300 mmHg), lower PEEP may be appropriate. 1, 2

• Apply PEEP ≥5 cmH₂O in all mechanically ventilated patients to prevent atelectasis 1, 3
• For moderate or severe ARDS, use higher PEEP strategies (conditional recommendation, moderate confidence) 1, 2
• Monitor for barotrauma when using PEEP >10 cmH₂O, particularly in patients with hemodynamic instability 2
• Consider recruitment maneuvers in moderate-to-severe ARDS, though this is a conditional recommendation with low confidence 1, 2

Severe ARDS: Aggressive Rescue Interventions

Prone Positioning (Strong Recommendation)

For severe ARDS with PaO₂/FiO₂ <150 mmHg, implement prone positioning for at least 12-16 hours daily—this is a strong recommendation that reduces mortality (RR 0.74). 1, 2

• Duration matters critically: trials with >12 hours/day proning showed mortality benefit, while shorter durations did not 2
• Do not delay prone positioning in severe ARDS—early implementation improves outcomes 2

Neuromuscular Blockade

For early severe ARDS with PaO₂/FiO₂ <150 mmHg, administer neuromuscular blocking agents for up to 48 hours. 2

• Use intermittent boluses rather than continuous infusion when possible 2
• Reserve continuous infusion for persistent ventilator dyssynchrony, need for deep sedation, prone positioning, or persistently high plateau pressures 2

Corticosteroids

Administer systemic corticosteroids to mechanically ventilated patients with ARDS (conditional recommendation, moderate certainty). 2

Oxygenation and Fluid Management

Oxygen Targets

• Target SpO₂ of 88-95% to avoid hyperoxia while maintaining adequate oxygenation 2, 3
• Start supplemental oxygen if SpO₂ <92%, and definitely if <90% 2
• Maintain SpO₂ no higher than 96% in acute hypoxemic respiratory failure 2
• Titrate FiO₂ to these targets rather than aiming for normoxia 3

Fluid Strategy

• Use a conservative fluid strategy in established ARDS without tissue hypoperfusion 2
• Conservative fluid management improves ventilator-free days without increasing non-pulmonary organ failures 2

Ventilator Settings and Monitoring

Respiratory Rate and Ventilation

• Set respiratory rate at 20-35 breaths per minute for most ARDS patients 3
• Adjust respiratory rate to maintain adequate ventilation while accepting permissive hypercapnia 2, 3
• Minimize sedation by targeting specific titration endpoints to facilitate patient-ventilator synchrony 2

Head of Bed Positioning

• Maintain head of bed elevated to 30-45 degrees to limit aspiration risk and prevent ventilator-associated pneumonia 1

Interventions to AVOID (Strong Recommendations Against)

Do not use high-frequency oscillatory ventilation in moderate or severe ARDS—this is strongly recommended against with high confidence in effect estimates. 1, 2

• Do not routinely use pulmonary artery catheters for ARDS management 2
• Do not use β-2 agonists for ARDS treatment without bronchospasm 2
• Do not use tidal volumes >8 mL/kg PBW even if plateau pressures are acceptable—both parameters must be optimized 2

ECMO for Refractory Hypoxemia

• For severe refractory ARDS despite optimized ventilation, proning, and rescue therapies, consider VV-ECMO only in carefully selected patients at experienced centers 2
• ECMO remains resource-intensive and should be reserved for centers with expertise 2

Critical Pitfalls to Avoid

• Do not prioritize normocapnia over lung-protective ventilation—accept permissive hypercapnia as necessary (pH >7.20) 2
• Do not delay prone positioning in severe ARDS—mortality benefit requires early implementation for >12 hours daily 2
• Do not use recruitment maneuvers routinely or for prolonged periods—these are associated with harm 2
• Do not apply higher PEEP indiscriminately—tailor to ARDS severity (higher for moderate-severe, lower for mild) and monitor hemodynamic tolerance 1, 2
• Do not use traditional tidal volumes (10-15 mL/kg)—meta-regression shows larger tidal volume gradients (difference between low and traditional) correlate with lower mortality risk 1

Special Consideration: COPD Patients

While the evidence base focuses on ARDS, lung-protective ventilation principles (low tidal volumes, plateau pressure limits) are safe and potentially beneficial in patients without ARDS at mechanical ventilation onset, including COPD patients 3. The same core principles apply: tidal volumes 4-8 mL/kg PBW, plateau pressures <30 cmH₂O, and PEEP ≥5 cmH₂O 3.