What is the management of Acute Respiratory Distress Syndrome (ARDS)?

Management of Acute Respiratory Distress Syndrome (ARDS)

Lung-protective ventilation with low tidal volumes (4-8 ml/kg predicted body weight) and plateau pressure ≤30 cmH₂O is the cornerstone of ARDS management, along with prone positioning for >12 hours daily in severe ARDS. 1

Definition and Classification

ARDS is characterized by:

• Onset within one week of a known insult or new/worsening respiratory symptoms
• Bilateral pulmonary opacities on chest imaging
• Respiratory failure not explained by cardiac failure or fluid overload
• Profound hypoxemia 2

Severity classification based on PaO₂/FiO₂ ratio:

• Mild: 201-300 mmHg
• Moderate: 101-200 mmHg
• Severe: ≤100 mmHg 1

Core Management Strategies

Ventilation Strategies

1. Lung-protective ventilation:

   • Tidal volume: 4-8 ml/kg predicted body weight
   • Plateau pressure: ≤30 cmH₂O
   • Target driving pressure <15 cmH₂O 1, 3

2. PEEP management:

   • Higher PEEP strategies are conditionally recommended for moderate to severe ARDS 4
   • PEEP titration by severity:
     • Mild ARDS: 5-10 cmH₂O
     • Moderate ARDS: 8-12 cmH₂O
     • Severe ARDS: 12-15+ cmH₂O 1

3. Oxygenation targets:

   • PaO₂: 70-90 mmHg
   • SpO₂: 92-97% (consider 88-92% in severe ARDS with high PEEP) 1

4. Avoid prolonged lung recruitment maneuvers:

   • Strong recommendation against prolonged recruitment maneuvers with high PEEP strategies 4

Adjunctive Therapies

1. Prone positioning:

   • Strongly recommended for severe ARDS (PaO₂/FiO₂ ≤100 mmHg)
   • Duration: >12 hours per day 1, 3

2. Neuromuscular blockade:

   • Conditionally recommended for early severe ARDS
   • Consider for refractory hypoxemia or ventilator dyssynchrony 4, 3

3. Corticosteroids:

   • Conditionally recommended for all ARDS patients
   • Most beneficial when started within 14 days of onset
   • Caution: administration beyond 14 days may worsen outcomes 1, 3

4. Venovenous ECMO (VV-ECMO):

   • Conditionally recommended for selected patients with severe ARDS refractory to conventional therapy 4, 1

5. Fluid management:

   • Conservative fluid management recommended for patients without tissue hypoperfusion
   • Target neutral-to-negative fluid balance 1, 3

Monitoring Parameters

• Dynamic compliance and resistance
• Mechanical power (aim for ≤17 J/min)
• Work of breathing
• Auto-PEEP detection
• Driving pressure (target <14-15 cmH₂O) 1

Common Pitfalls and Considerations

1. Underrecognition:

   • ARDS is often underdiagnosed, delaying appropriate management 5
   • Clinician interpretation of chest radiographs and edema origin may be unreliable 5

2. Ventilator-induced lung injury:

   • Excessive tidal volumes and pressures can worsen lung injury
   • Prioritize lung-protective strategies even if they result in permissive hypercapnia 1

3. Failed pharmacologic interventions:

   • β2 agonists, statins, and keratinocyte growth factor have shown no benefit and potential harm 5
   • Aspirin is not effective for ARDS prevention 5

4. Post-ARDS complications:

   • Survivors are at risk for diminished functional capacity, mental illness, and decreased quality of life 2
   • Early rehabilitation is important to improve outcomes 1

Weaning from Mechanical Ventilation

• Initiate weaning as soon as clinically appropriate
• Perform daily spontaneous breathing trials when ready
• Consider extubation if spontaneous breathing trial is successful
• Non-invasive ventilation may be beneficial post-extubation in selected patients 1

Supportive Care

• DVT prophylaxis
• Stress ulcer prophylaxis
• Appropriate nutritional support via enteral route when possible
• Treatment of underlying cause (e.g., antibiotics for pneumonia, source control for sepsis) 1, 3

The management of ARDS continues to evolve, with ongoing research focused on improving outcomes. Current evidence strongly supports lung-protective ventilation strategies and prone positioning for severe cases, while other interventions should be applied based on individual patient characteristics and disease severity.