What is the recommended management strategy for critically ill patients with Acute Respiratory Distress Syndrome (ARDS)?

Management of Acute Respiratory Distress Syndrome (ARDS)

For critically ill patients with ARDS, implement lung-protective ventilation with tidal volumes of 4-8 mL/kg predicted body weight and plateau pressures <30 cmH2O, combined with prone positioning for severe cases, higher PEEP strategies for moderate-to-severe disease, and consideration of corticosteroids and neuromuscular blockade in selected patients. 1

Core Ventilation Strategy: Lung-Protective Ventilation

All ARDS patients require low tidal volume ventilation as the foundation of management. 1

• Set tidal volume at 6 mL/kg predicted body weight (range 4-8 mL/kg PBW) 1, 2

  • Males: PBW = 50 + 0.91 × [height (cm) - 152.4] kg 1
  • Females: PBW = 45.5 + 0.91 × [height (cm) - 152.4] kg 1

• Maintain plateau pressure <30 cmH2O 1, 2

• Accept permissive hypercapnia as a consequence of lung protection, maintaining pH >7.20 3

The landmark ARDS Network trial demonstrated mortality reduction from 39.8% to 31.0% with 6 mL/kg versus 12 mL/kg tidal volumes (number-needed-to-treat of 12 patients). 4 This represents the single most impactful intervention in ARDS management. Meta-regression analysis shows that larger tidal volume gradients between intervention and control groups correlate with greater mortality benefit. 1

PEEP Strategy: Titrate to Disease Severity

For moderate-to-severe ARDS (PaO₂/FiO₂ <200 mmHg), use higher PEEP (typically >10 cmH2O); for mild ARDS (PaO₂/FiO₂ 200-300 mmHg), lower PEEP may be appropriate. 1, 3

• Higher PEEP strategy is suggested for moderate-to-severe ARDS 1, 3
• Monitor for barotrauma when using PEEP >10 cmH2O 1
• In patients with cirrhosis or hemodynamic instability, use lower PEEP (<10 cmH2O) for mild ARDS to avoid impairing venous return 1

The evidence shows that higher PEEP combined with low tidal volume provides greater mortality benefit than low tidal volume alone (RR 0.58 vs 0.87). 1 However, three large randomized trials showed no benefit of higher PEEP in unselected ALI/ARDS patients, with meta-analysis suggesting benefit only in ARDS (not milder ALI). 4

Avoid prolonged recruitment maneuvers—these are strongly recommended against. 1

Prone Positioning: Essential for Severe ARDS

For severe ARDS with PaO₂/FiO₂ <150 mmHg, implement prone positioning for at least 12-16 hours daily. 1

• This is a strong recommendation with moderate-quality evidence 1
• Prone positioning reduces mortality in severe ARDS (RR 0.74) 1
• Duration matters: trials with >12 hours/day proning showed mortality benefit, while shorter durations did not 1

The most recent high-quality evidence demonstrates that prone positioning for prolonged periods (12-16 hours) improves survival specifically in severe ARDS by improving ventilation-perfusion matching, increasing end-expiratory lung volume, and reducing ventilator-induced lung injury through more uniform tidal volume distribution. 1

Neuromuscular Blockade: Early Use in Severe ARDS

For early severe ARDS with PaO₂/FiO₂ <150 mmHg, use neuromuscular blocking agents for up to 48 hours. 1

• Administer as intermittent boluses rather than continuous infusion when possible 1
• Use continuous infusion only for persistent ventilator dyssynchrony, need for deep sedation, prone positioning, or persistently high plateau pressures 1
• Cisatracurium is suggested for 48 hours in patients with PaO₂/FiO₂ ≤20 kPa (approximately 150 mmHg) 5

This is a conditional recommendation with low certainty of evidence, but the 2024 ATS guideline maintains this suggestion based on potential benefits in facilitating lung-protective ventilation. 1

Corticosteroids: Suggested for ARDS

Administer systemic corticosteroids to mechanically ventilated patients with ARDS. 1

• This is a conditional recommendation with moderate certainty of evidence 1
• The 2024 ATS guideline represents the most recent high-quality recommendation supporting corticosteroid use 1
• Do not use corticosteroids routinely in respiratory failure without ARDS 1

The 2024 update marks a shift from the 2019 UK guideline that made only a research recommendation for corticosteroids. 5 The moderate certainty evidence now supports their use, though individual patient factors should guide implementation.

Fluid Management: Conservative Strategy

Use a conservative fluid strategy in established ARDS without tissue hypoperfusion. 1, 5

• This is a strong recommendation with moderate-quality evidence 1
• Conservative fluid management improves ventilator-free days without increasing non-pulmonary organ failures 1

Rescue Therapies for Refractory Hypoxemia

Venovenous ECMO

For severe refractory ARDS despite optimized ventilation, proning, and rescue therapies, consider VV-ECMO in carefully selected patients at experienced centers. 1

• This is a conditional recommendation with low certainty of evidence 1
• ECMO should only be considered in carefully selected patients due to resource-intensive nature 1

Inhaled Pulmonary Vasodilators

Do not routinely use inhaled nitric oxide in mechanically ventilated ARDS patients. 1, 5

• If used as rescue therapy for severe refractory hypoxemia, taper off rapidly if no improvement in oxygenation occurs 1
• Inhaled nitric oxide is ineffective in adult ARDS and does not improve mortality or ventilator-free days 6

The FDA label explicitly states that despite acute improvements in oxygenation, nitric oxide showed no effect on days alive and off ventilator support in a 385-patient ARDS trial. 6

Interventions to Avoid

Do not use high-frequency oscillatory ventilation—this is strongly recommended against. 1, 5

Do not routinely use pulmonary artery catheters for ARDS management. 1

Do not use β-2 agonists for ARDS treatment without bronchospasm. 1

Oxygenation Targets

Target SpO₂ of 88-95% to avoid hyperoxia while maintaining adequate oxygenation. 2, 7

• Start supplemental oxygen if SpO₂ <92%, and definitely if <90% 1
• Maintain SpO₂ no higher than 96% in acute hypoxemic respiratory failure 1

Sedation and Weaning

Minimize continuous or intermittent sedation, targeting specific titration endpoints. 1

Use spontaneous breathing trials in patients ready for weaning. 1

Implement a weaning protocol for patients who can tolerate weaning. 1

Common Pitfalls to Avoid

• Do not prioritize normocapnia over lung-protective ventilation—accept permissive hypercapnia as necessary 3
• Do not use tidal volumes >8 mL/kg PBW even if plateau pressures are acceptable—both parameters must be optimized 1, 2
• Do not delay prone positioning in severe ARDS—early implementation improves outcomes 1
• Do not use recruitment maneuvers routinely or for prolonged periods—these are associated with harm 1
• Do not apply higher PEEP indiscriminately—tailor to ARDS severity and hemodynamic tolerance 1