## Pathophysiology and Evidence-Based Management of ARDS ### Key Point: **Inhaled nitric oxide (iNO) does NOT reduce mortality in ARDS** — it may improve oxygenation transiently but has no survival benefit and is not recommended as monotherapy. ### High-Yield Evidence Summary | Intervention | Evidence | Mortality Benefit | Recommendation | |---|---|---|---| | Lung-protective ventilation (6–8 mL/kg PBW) | ARDSNET trial | Yes, ~22% mortality reduction | **Standard of care** | | Conservative fluid management | FACCT trial | Yes, reduces ventilator days & ICU LOS | **Recommended** | | Prone positioning (≥12 hrs/day) | PROSEVA trial | Yes, in moderate-severe ARDS (PaO₂/FiO₂ <150) | **Recommended** | | Inhaled nitric oxide (iNO) monotherapy | Multiple RCTs | **No mortality benefit** | **Not recommended alone** | | ECMO | EOLIA, CESAR trials | Potential benefit in refractory hypoxemia | **Rescue therapy** | | Corticosteroids (early, moderate-dose) | ARDS Network trials | Modest reduction in ventilator days | **Consider in early ARDS** | ### Clinical Pearl: **iNO mechanism:** Inhaled nitric oxide is a selective pulmonary vasodilator that improves ventilation-perfusion matching in well-ventilated lung units. However, it does NOT address the underlying inflammatory process or prevent alveolar damage. While it may transiently improve PaO₂, it does not reduce mortality and is expensive — use is reserved for refractory hypoxemia as a bridge to ECMO, not as primary therapy. ### Why This Question Tests High-Yield Knowledge: - **Lung-protective ventilation** (Option 3) is the cornerstone of ARDS management — ARDSNET trial landmark evidence [cite:Harrison 21e Ch 295]. - **Conservative fluid management** (Option 1) reduces complications without worsening outcomes — FACCT trial evidence. - **Prone positioning** (Option 0) improves oxygenation and mortality in moderate-to-severe ARDS — PROSEVA trial. - **iNO monotherapy** (Option 2) is a common NEET PG trap — students often confuse "improves oxygenation" with "improves mortality." iNO does the former but NOT the latter. ### Mnemonic: **"iNO = Oxygenation, NOT Outcome"** — remember that iNO improves blood gases transiently but has no survival benefit in ARDS. ### Warning: ~~Do not confuse transient improvement in PaO₂ with mortality benefit.~~ Many interventions (inhaled vasodilators, surfactant, high-frequency ventilation) improve oxygenation acutely but do not reduce mortality in ARDS.
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