What are the management strategies for Acute Respiratory Distress Syndrome (ARDS)?

Management of Acute Respiratory Distress Syndrome (ARDS)

Diagnostic Classification

ARDS severity must be classified using the Berlin Definition based on PaO₂/FiO₂ ratio: mild (201-300 mmHg), moderate (101-200 mmHg), and severe (<100 mmHg), with bilateral pulmonary opacities on imaging and respiratory failure not fully explained by cardiac failure. 1, 2

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Mandatory Lung-Protective Ventilation Strategy

All mechanically ventilated ARDS patients must receive low tidal volume ventilation with 4-8 mL/kg predicted body weight (targeting 6 mL/kg) and plateau pressure ≤30 cmH₂O. 1

• This is a strong recommendation with moderate confidence in effect estimates, representing the cornerstone of ARDS management 1
• Meta-regression demonstrates that larger tidal volume gradients (greater difference between low and traditional volumes) correlate with lower mortality risk 1
• Driving pressure (plateau pressure minus PEEP) is a better predictor of outcome than tidal volume or plateau pressure alone 1
• Target SpO₂ no higher than 96% to avoid oxygen toxicity 3, 2

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PEEP Strategy

For moderate to severe ARDS (PaO₂/FiO₂ <200 mmHg), use higher PEEP without prolonged lung recruitment maneuvers. 1, 3

• Higher PEEP is a conditional recommendation with low to moderate certainty of evidence 1
• Strongly recommend against prolonged lung recruitment maneuvers in moderate to severe ARDS (strong recommendation, moderate certainty) 1, 4
• Recruitment maneuvers are most effective in early ARDS patients without chest wall mechanics impairment and with large recruitment potential 5
• Day 1 PEEP should be increased to approximately 8 cmH₂O in ARDS patients 6

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Prone Positioning

Implement prone positioning for >12 hours daily (ideally 12-16 hours) in all patients with severe ARDS (PaO₂/FiO₂ <100 mmHg). 1, 3

• This is a strong recommendation with moderate to high confidence in effect estimates 1
• Prone positioning reduces mortality in severe ARDS with RR 0.74 (95% CI 0.56-0.99) when applied >12 hours daily 1
• The mortality benefit is confirmed in patient-level meta-analyses and the PROSEVA trial 1
• Deep sedation and analgesia should be applied during prone positioning 2
• Common pitfall: Delaying prone positioning in severe ARDS significantly worsens outcomes 4

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Corticosteroids

Use systemic corticosteroids for patients with ARDS. 1, 3, 4

• This is a conditional recommendation with moderate certainty of evidence 1
• Particularly beneficial in COVID-19 ARDS with demonstrated mortality benefit 3

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Neuromuscular Blocking Agents

Consider neuromuscular blocking agents (specifically cisatracurium) in early severe ARDS (PaO₂/FiO₂ <100 mmHg). 1, 3, 2

• This is a conditional recommendation with low certainty of evidence 1
• Administer for 48 hours to improve ventilator synchrony and reduce oxygen consumption 2, 7
• Particularly beneficial when ventilator-patient dyssynchrony persists despite sedation 2
• Note the contrast with broader PEEP recommendations: NMBAs are specifically for early severe ARDS only 1

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Fluid Management

Implement a conservative fluid management strategy to minimize pulmonary edema while maintaining adequate organ perfusion. 3, 4, 2, 7

• Avoid fluid overload, which worsens oxygenation, promotes right ventricular failure, and increases mortality 3, 2
• In acute pancreatitis-related ARDS, use non-aggressive fluid resuscitation at 1.5 mL/kg/hr after initial 10 mL/kg bolus, with total crystalloid <4000 mL in first 24 hours 4
• Prefer Lactated Ringer's solution; avoid hydroxyethyl starch 4

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Venovenous ECMO for Refractory Severe ARDS

Consider VV-ECMO in selected patients with severe ARDS (PaO₂/FiO₂ <100 mmHg) who fail conventional management. 1, 3, 2

• This is a conditional recommendation with low certainty of evidence 1
• Only implement at centers with ECMO expertise 2
• Reserve for patients with reversible disease and adequate candidacy 2

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Rescue Therapies for Refractory Hypoxemia

Consider a trial of inhaled pulmonary vasodilators as rescue therapy for severe hypoxemia despite optimized ventilation, but discontinue if no rapid improvement occurs. 3, 2

• Do not routinely use inhaled nitric oxide 3, 7
• Strongly recommend against high-frequency oscillatory ventilation in moderate or severe ARDS (strong recommendation, high confidence) 1

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Monitoring Requirements

Continuously monitor oxygen saturation, respiratory mechanics (plateau pressure, driving pressure), hemodynamics, and right ventricular function via echocardiography. 3, 4, 2

• Assess for ventilator-patient dyssynchrony 2
• Monitor for acute cor pulmonale in severe cases 3, 4
• Maintain arterial saturation >95% 4

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Ventilator Liberation

Perform daily spontaneous breathing trials once the patient's condition improves to assess eligibility for ventilator weaning. 2

• Use noninvasive ventilation after extubation for high-risk patients to reduce ICU length of stay and mortality 2

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Critical Implementation Gaps

Evidence-based ARDS interventions remain significantly underused in clinical practice, directly contributing to increased mortality. 1

• Despite strong evidence, considerable practice variation exists 1
• The underutilization of lung-protective ventilation and prone positioning represents a major quality gap 1
• Two recommendations are suitable for performance measure development: low tidal volume ventilation and prone positioning in severe ARDS 1