## Diagnosis and Rationale This patient meets Berlin criteria for ARDS (PaO₂/FiO₂ = 180, bilateral infiltrates, reduced compliance, acute onset). The next step in oxygenation management is **lung recruitment and PEEP titration**. **Key Point:** PEEP is the cornerstone of ARDS management. Current PEEP (5 cm H₂O) is suboptimal for moderate ARDS. Increasing PEEP to 10–15 cm H₂O recruits collapsed alveoli, improves oxygenation, and reduces ventilator-induced lung injury (VILI). **High-Yield:** ARDS management follows a stepwise escalation: 1. Optimize PEEP (start 5, titrate to 10–15 for moderate ARDS) 2. Increase FiO₂ if needed (already at 0.6) 3. Consider prone positioning if PaO₂/FiO₂ < 150 after PEEP optimization 4. ECMO only if refractory hypoxaemia despite maximal ventilatory support **Clinical Pearl:** Lung-protective ventilation (Vt 6–8 mL/kg IBW, Pplat < 30 cm H₂O) combined with appropriate PEEP is the evidence-based foundation. PEEP recruitment is attempted *before* escalating to advanced therapies. ## Why This Approach Works ```mermaid flowchart TD A[ARDS diagnosed<br/>PaO₂/FiO₂ 180]:::outcome --> B{Current PEEP adequate?}:::decision B -->|No, PEEP ≤ 5| C[Increase PEEP to 10-15 cm H₂O]:::action B -->|Yes, optimized| D{PaO₂/FiO₂ still < 100?}:::decision C --> E[Reassess oxygenation<br/>& compliance]:::action E --> F{Response achieved?}:::decision F -->|Yes| G[Continue lung-protective<br/>ventilation]:::action F -->|No| H[Consider prone positioning]:::action D -->|Yes| H H --> I{Still refractory?}:::decision I -->|Yes| J[ECMO consideration]:::urgent I -->|No| G ``` **Citation:** [cite:Harrison 21e Ch 289]
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