What are the recommended mechanical ventilation targets for patients with Acute Respiratory Distress Syndrome (ARDS)?

Mechanical Ventilation Targets in ARDS

For patients with ARDS, use a tidal volume of 6 mL/kg predicted body weight (not actual weight), maintain plateau pressure ≤30 cmH2O, and apply higher PEEP (>10 cmH2O) for moderate-to-severe disease, with prone positioning for at least 12 hours daily when PaO2/FiO2 <150 mmHg. 1, 2

Core Ventilator Settings

Tidal Volume

• Set tidal volume at 6 mL/kg predicted body weight (strong recommendation, high quality evidence) 1, 2
• Calculate using height and sex-based formulas, never actual body weight—this applies even in obese patients 2
• This target is superior to 12 mL/kg and reduces mortality 1, 3
• Acceptable range is 4-8 mL/kg if needed to maintain plateau pressure targets 2, 4

Plateau Pressure

• Maintain plateau pressure ≤30 cmH2O as an upper limit goal (strong recommendation, moderate quality evidence) 1, 2
• Measure plateau pressures in all ARDS patients during passive inflation 1
• If plateau pressure exceeds 30 cmH2O, reduce tidal volume further (down to 4 mL/kg if necessary) 2
• Driving pressure (plateau pressure minus PEEP) may be a better predictor of outcomes than either measure alone 2

PEEP Strategy

• For mild ARDS: use lower PEEP (<10 cmH2O) 2
• For moderate-to-severe ARDS: use higher PEEP (>10 cmH2O, typically 10-15 cmH2O) (weak recommendation, moderate quality evidence) 1, 2, 4
• Apply PEEP to prevent alveolar collapse at end-expiration (atelectotrauma) 1
• Titrate PEEP to optimize oxygenation while monitoring for hemodynamic compromise 2

Adjunctive Strategies for Severe ARDS

Prone Positioning

• Implement prone positioning for patients with PaO2/FiO2 <150 mmHg (strong recommendation, moderate quality evidence) 1, 2
• Position prone for >12 hours per day (some sources recommend at least 16 hours) to maximize mortality benefit 2, 4, 5, 3
• This requires facilities with experience in prone positioning 1

Recruitment Maneuvers

• Use recruitment maneuvers in severe ARDS with refractory hypoxemia (weak recommendation, moderate quality evidence) 1, 4
• Consider in patients with moderate or severe ARDS 4

Neuromuscular Blockade

• Consider neuromuscular blocking agents (cisatracurium) for ≤48 hours when PaO2/FiO2 <150 mmHg 2, 3
• This improves ventilator synchrony and reduces work of breathing 2

Fluid Management

• Use a conservative fluid strategy for established ARDS without tissue hypoperfusion (weak recommendation, moderate quality evidence) 1, 2, 4, 3
• Avoid fluid overload as it worsens lung edema and gas exchange 2

Oxygenation Targets

• Target oxygen saturation of 88-92% for most patients to avoid oxygen toxicity 4
• Titrate FiO2 to maintain SpO2 88-95% 6

What to Avoid

High-Frequency Oscillatory Ventilation

• Do not use high-frequency oscillatory ventilation (strong recommendation, moderate quality evidence) 1, 2, 4, 3

Excessive Tidal Volumes

• Never use tidal volumes >8 mL/kg predicted body weight—this increases ventilator-induced lung injury risk 2, 4

Inhaled Vasodilators

• Do not routinely use inhaled nitric oxide 3
• Beta-2 agonists should not be used unless bronchospasm is present 2

Monitoring and Supportive Care

Head of Bed Elevation

• Elevate head of bed 30-45 degrees to reduce ventilator-associated pneumonia risk 1, 2

Weaning Protocol

• Implement a weaning protocol with regular spontaneous breathing trials 1, 2
• Criteria for trial: arousable, hemodynamically stable (no vasopressors), no new serious conditions, low ventilatory requirements, low PEEP requirements, low FiO2 requirements 1

Pulmonary Artery Catheter

• Do not routinely use pulmonary artery catheters (strong recommendation) 1

Rescue Therapy for Refractory Hypoxemia

• Consider ECMO as adjunct to protective ventilation for very severe ARDS when conventional strategies fail 2, 4, 5, 3

Common Pitfalls to Avoid

• Using actual body weight instead of predicted body weight for tidal volume calculation leads to excessive volumes and barotrauma 2
• Failing to measure plateau pressures regularly—this is essential for lung-protective ventilation 1
• Delaying prone positioning in severe ARDS (PaO2/FiO2 <150)—early implementation improves outcomes 2, 4
• Liberal fluid administration worsening pulmonary edema in established ARDS 2, 3