What is the recommended treatment approach for a patient with acute respiratory distress syndrome (ARDS)?

Treatment of Acute Respiratory Distress Syndrome

All patients with ARDS must receive lung-protective mechanical ventilation with tidal volumes of 4-8 ml/kg predicted body weight and plateau pressure ≤30 cmH2O, and patients with severe ARDS (PaO2/FiO2 <150 mmHg) require prone positioning for more than 12 hours daily. 1

Core Mechanical Ventilation Strategy

Mandatory Lung-Protective Settings

• Set tidal volume at 4-8 ml/kg predicted body weight (males = 50 + 0.91[height(cm) - 152.4] kg; females = 45.5 + 0.91[height(cm) - 152.4] kg) 1
• Maintain plateau pressure ≤30 cmH2O to prevent ventilator-induced lung injury 1, 2
• Target driving pressure (plateau pressure minus PEEP) <14 cmH2O, as this is a major mortality risk factor 2, 3
• Keep mechanical power <20 J/min when possible to minimize lung injury 4

This strong recommendation is based on moderate-quality evidence showing mortality reduction when larger tidal volume gradients (difference between low and traditional volumes) are achieved. 1 The evidence demonstrates that trials with tidal volumes around 6.8 ml/kg versus 11.4 ml/kg showed significant mortality benefit. 1

PEEP Management by Severity

• For moderate to severe ARDS (PaO2/FiO2 ≤200 mmHg): Use higher PEEP averaging 15 cmH2O compared to lower PEEP of 9 cmH2O 4
• For all ARDS: Maintain PEEP ≥5 cmH2O minimum, titrating to ≥10 cmH2O for moderate-severe cases 5
• Titrate PEEP to best respiratory system compliance or use advanced methods like esophageal manometry 6

The recommendation for higher PEEP in moderate-severe ARDS is conditional with moderate confidence, meaning clinical judgment is needed but the evidence favors this approach. 1

Prone Positioning Protocol

Indications and Duration

• Implement prone positioning for >12 hours daily in severe ARDS (PaO2/FiO2 <150 mmHg) 1
• This is a strong recommendation with moderate-quality evidence showing mortality reduction (RR 0.74,95% CI 0.56-0.99) 1
• Do not delay prone positioning as a last resort—implement early in severe cases 4, 5

The subgroup analysis clearly demonstrates that prone positioning only reduces mortality when applied for >12 hours daily and in patients with severe hypoxemia. 1 Shorter durations or use in mild ARDS does not show benefit.

Recruitment Maneuvers

• Consider recruitment maneuvers in moderate to severe ARDS with close hemodynamic monitoring 1, 4
• Avoid in patients with hypovolemia or shock due to risk of hemodynamic compromise 4
• This is a conditional recommendation with low confidence in effect estimates 1

Interventions to Avoid

Strong Recommendation Against

• Do not use high-frequency oscillatory ventilation routinely in moderate or severe ARDS 1
• This strong recommendation is based on high confidence evidence showing no benefit and potential harm 1

Limited Evidence Interventions

• Inhaled nitric oxide provides only short-term oxygenation improvement without survival benefit—suggest not using routinely 7
• Neuromuscular blockade with cisatracurium may be considered when plateau pressures exceed 30-35 cmH2O, but use judiciously 5, 7

Supportive Care Bundle

Fluid Management

• Use conservative fluid management strategy to avoid pulmonary edema worsening 6, 7, 8
• Maintain euvolemia rather than inducing hypervolemia 5

Daily Assessments

• Perform daily sedation interruptions and spontaneous breathing trials to reduce ventilator time by 81% and mortality by 49% 5
• Provide DVT prophylaxis (pharmacological or mechanical) 5
• Implement stress ulcer prophylaxis 6

Monitoring Parameters

• Track plateau pressure, driving pressure, and dynamic compliance to assess lung mechanics 2, 5
• Monitor for acute cor pulmonale (occurs in 20-25% of ARDS cases) using echocardiography, requiring immediate ventilator adjustment 2
• Maintain oxygenation targets of PaO2 70-90 mmHg or SpO2 88-92% to avoid oxygen toxicity 5

Rescue Therapies for Refractory Hypoxemia

ECMO Consideration

• Consider veno-venous ECMO in very severe ARDS with refractory hypoxemia as an adjunct to protective ventilation 6, 7
• This allows for lung rest and modestly improves survival in select cases 6
• Evidence is insufficient for definitive recommendation, but it serves as salvage therapy 1

Alternative Ventilation Modes

• High-frequency oscillatory ventilation and airway pressure release ventilation may be options in select refractory patients, though evidence is limited 6

Common Pitfalls to Avoid

• Do not use traditional tidal volumes of 10-15 ml/kg—this increases mortality 1
• Do not delay prone positioning in severe ARDS—early implementation is critical 4, 5
• Do not induce hypervolemia—conservative fluid strategy is essential 5
• Do not use absolute mechanical power without normalization—it lacks causal relationship with mortality 4
• Do not overlook ARDS recognition—it is frequently underdiagnosed and evidence-based interventions underused 1