All the following features are seen in ARDS except
**Core Concept**
Acute Respiratory Distress Syndrome (ARDS) is a life-threatening condition characterized by rapid onset of inflammation and injury to the lung tissue, leading to impaired gas exchange and severe hypoxemia. This condition is often triggered by severe illness, trauma, or sepsis, and is associated with high morbidity and mortality rates.
**Why the Correct Answer is Right**
ARDS is characterized by the following features:
- Bilateral lung infiltrates on chest radiography, typically within 48 hours of a known clinical insult.
- Severe hypoxemia, defined as a PaO2/FiO2 ratio ≤ 300 mmHg.
- No evidence of left atrial hypertension, as indicated by a wedge pressure ≤ 18 mmHg.
- Impaired lung function, often requiring mechanical ventilation.
**Why Each Wrong Option is Incorrect**
**Option A:** Not a feature of ARDS.
**Option B:** Actually, a key feature of ARDS.
**Option C:** This is a hallmark of ARDS, reflecting the impaired lung function.
**Clinical Pearl / High-Yield Fact**
To differentiate ARDS from cardiogenic pulmonary edema, consider the following: if the PaO2/FiO2 ratio is normal or elevated, and the patient has evidence of left atrial hypertension, then cardiogenic pulmonary edema is more likely.
**Correct Answer: C. This is a hallmark of ARDS, reflecting the impaired lung function.**