Management of Acute Respiratory Distress Syndrome (ARDS)
The management of ARDS should follow a structured approach including lung-protective ventilation strategies, appropriate PEEP settings, prone positioning, and adjunctive therapies such as corticosteroids and neuromuscular blockers based on disease severity. 1, 2
Diagnosis and Classification
ARDS is classified based on the PaO₂/FiO₂ ratio:
- Mild: 201-300 mmHg
- Moderate: 101-200 mmHg
- Severe: ≤100 mmHg 2
Diagnostic criteria include:
- Onset within one week of a known insult or worsening respiratory symptoms
- Bilateral pulmonary opacities on chest imaging
- Respiratory failure not explained by cardiac failure or fluid overload 3
Core Management Strategies
Lung-Protective Ventilation
- Use low tidal volumes (4-8 mL/kg predicted body weight) 1
- Maintain plateau pressure ≤30 cmH₂O
- Target driving pressure <15 cmH₂O 2
- Calculate predicted body weight using:
- Males: PBW (kg) = 50 + 0.91 × (height [cm] − 152.4)
- Females: PBW (kg) = 45.5 + 0.91 × (height [cm] − 152.4) 2
PEEP Strategy
- For moderate to severe ARDS: Use higher PEEP without lung recruitment maneuvers (conditional recommendation, low to moderate certainty) 1
- For all ARDS patients: Minimum PEEP of 5 cmH₂O 2
- Avoid prolonged lung recruitment maneuvers in moderate to severe ARDS (strong recommendation, moderate certainty) 1
Prone Positioning
- Implement prone positioning for >12 hours/day in severe ARDS (PaO₂/FiO₂ ≤100 mmHg) 2
- Initiate early rather than as a rescue strategy 2
Adjunctive Therapies Based on Severity
For All ARDS Patients
- Conservative fluid management after initial resuscitation 2
- Prophylaxis for stress ulcers and venous thromboembolism 3
- Target PaO₂ between 70-90 mmHg or SaO₂ between 92-97% 2
For Moderate to Severe ARDS
- Corticosteroids: Suggested for patients with ARDS (conditional recommendation, moderate certainty) 1, 2
For Severe ARDS (PaO₂/FiO₂ ≤100 mmHg)
- Neuromuscular blockers: Suggested in early severe ARDS (conditional recommendation, low certainty) 1, 2
- VV-ECMO: Consider in selected patients with severe ARDS (conditional recommendation, low certainty) 1
- Best candidates: PaO₂/FiO₂ <80 mmHg, pH <7.25 with PaCO₂ >60 mmHg, early ARDS course (<7 days), and reversible etiology 2
Management Algorithm by ARDS Severity
| Severity | PaO₂/FiO₂ | Primary Interventions |
|---|---|---|
| Mild | 201-300 mmHg | • Lung-protective ventilation • Low PEEP strategy (5-10 cmH₂O) • Conservative fluid management |
| Moderate | 101-200 mmHg | • Lung-protective ventilation • Higher PEEP strategy • Consider corticosteroids • Conservative fluid management |
| Severe | ≤100 mmHg | • Lung-protective ventilation • Higher PEEP strategy • Prone positioning >12h/day • Neuromuscular blockers • Corticosteroids • Consider VV-ECMO in selected patients |
Common Pitfalls and Caveats
- Avoid excessive tidal volumes even in patients without ARDS, as observational evidence suggests benefit from limiting tidal volumes in all mechanically ventilated patients 4
- Avoid inappropriate PEEP in mild ARDS as it may impede venous return without significant benefit 2
- Monitor for hemodynamic instability with higher PEEP strategies, particularly in patients with vasodilation 2
- Do not delay prone positioning in severe ARDS; implement early rather than as a rescue strategy 2
- Avoid high-frequency oscillatory ventilation as routine therapy in ARDS (may be considered only as rescue therapy) 5, 6
By following these evidence-based strategies tailored to ARDS severity, clinicians can optimize outcomes for patients with this life-threatening condition.