What is the treatment approach for a patient with Acute Respiratory Distress Syndrome (ARDS)?

Treatment of ARDS

Immediately implement lung-protective mechanical ventilation with tidal volumes of 4-8 mL/kg predicted body weight and plateau pressures ≤30 cmH₂O as the cornerstone of ARDS management, while simultaneously treating the underlying cause. 1

Initial Respiratory Support Strategy

For mild ARDS (PaO₂/FiO₂ 200-300 mmHg):

• Consider a trial of high-flow nasal cannula (HFNC) starting at 30-40 L/min with FiO₂ 50-60% only in hemodynamically stable, alert, cooperative patients without pneumonia as the ARDS etiology 1
• Proceed to intubation in a controlled setting if deterioration occurs within 1 hour, FiO₂ exceeds 70%, or flow exceeds 50 L/min 2, 1
• Avoid NIV in patients with impaired consciousness, hemodynamic instability, copious secretions, or multi-organ failure 1

For moderate-to-severe ARDS:

• Proceed directly to intubation rather than attempting noninvasive support, as failure rates are high and delayed intubation worsens outcomes 1

Lung-Protective Mechanical Ventilation (All Intubated Patients)

Ventilator settings:

• Set tidal volume at 4-8 mL/kg predicted body weight (not actual weight) 2, 1
• Maintain plateau pressure ≤30 cmH₂O at all times 2, 1
• Apply higher PEEP in moderate-to-severe ARDS using the ARDS-network PEEP-to-FiO₂ grid, monitoring for hemodynamic compromise 2, 1

Oxygenation targets:

• Target SpO₂ 92-96% (do not exceed 96% to avoid oxygen toxicity) 2, 1
• Target PaO₂ 70-90 mmHg 2

Fluid Management

Once respiratory status is stabilized:

• Implement conservative fluid management to minimize pulmonary edema while maintaining adequate organ perfusion 2, 1
• Avoid excessive fluid administration, which worsens oxygenation, promotes right ventricular failure, and increases mortality 2, 1

Critical caveat: This applies only to true ARDS—if cardiogenic pulmonary edema is the diagnosis, aggressive diuresis is required instead 3

Adjunctive Therapies for Severe ARDS (PaO₂/FiO₂ <100 mmHg)

Prone positioning:

• Implement prone positioning for at least 12 hours per day in severe ARDS, as this has demonstrated significant mortality reduction 2, 1
• Apply deep sedation and analgesia during prone positioning 1

Neuromuscular blockade:

• Consider cisatracurium infusion for 24-48 hours after ARDS onset in severe ARDS to improve ventilator synchrony, reduce oxygen consumption, and potentially improve outcomes 2, 1
• Particularly beneficial when ventilator-patient dyssynchrony persists despite sedation 1

Treatment of Underlying Cause

This is fundamental and often overlooked:

• Rapidly identify and treat the underlying etiology, as this is the only causal treatment measure 4, 5
• For COVID-19 pneumonia, dexamethasone has proven effective 4
• For infectious causes, initiate targeted antimicrobial therapy 3
• For drug-induced lung injury, immediately withdraw the offending agent 3
• For immunologic conditions, consider corticosteroids or immunosuppression 3

Rescue Therapies for Refractory Hypoxemia

When conventional management fails:

• Consider inhaled pulmonary vasodilators (inhaled nitric oxide) as rescue therapy, but discontinue if no rapid improvement in oxygenation 1
• Consider VV-ECMO only at centers with ECMO expertise for patients with severe ARDS failing conventional management, particularly those with potentially reversible disease 2, 1, 5

Monitoring Requirements

Continuous assessment is essential:

• Monitor oxygen saturation, respiratory mechanics, and hemodynamics continuously 2, 1
• Assess right ventricular function via echocardiography, as RV failure significantly worsens outcomes 2, 1
• Perform daily spontaneous breathing trials once the patient's condition improves to reduce duration of mechanical ventilation 1

Critical Pitfalls to Avoid

Avoid iatrogenic "second hits":

• Excessive fluid administration, blood product transfusions, and injurious mechanical ventilation can aggravate lung injury 4
• High tidal volumes and plateau pressures above 30 cmH₂O cause ventilator-induced lung injury 4

Recognize ARDS mimics:

• Establish a diagnostic protocol to identify treatable diseases that mimic ARDS (diffuse interstitial lung diseases, drug-induced lung injury, cardiogenic pulmonary edema), as these require specific therapies rather than standard ARDS management 3
• Obtain detailed exposure history, comprehensive infectious workup, immunologic evaluation, and cardiac assessment when clinical suspicion exists 3

Avoid delayed intubation:

• Patients managed with NIV or HFNO whose clinical conditions do not stabilize and who require intubation have worse outcomes 4