True statement regarding Acute high altitude pulmonary edema ncludes
**Core Concept**
Acute high-altitude pulmonary edema (HAPE) is a life-threatening condition that occurs when individuals ascend to high altitudes, leading to pulmonary edema due to increased pressures in the pulmonary capillaries. The underlying mechanism involves hypoxia-induced vasoconstriction of pulmonary arterioles, resulting in increased pulmonary artery pressures and subsequent leakage of fluid into the alveoli.
**Why the Correct Answer is Right**
The pathophysiology of HAPE involves the mismatch between ventilation and perfusion in the lungs, leading to hypoxia. This hypoxia triggers the release of endothelin-1, a potent vasoconstrictor, which causes pulmonary arteriole constriction. The increased pulmonary artery pressures lead to fluid leakage into the alveoli, causing pulmonary edema. The correct answer choice will reflect this pathophysiological mechanism.
**Why Each Wrong Option is Incorrect**
**Option A:** This option may describe a different condition, such as high-altitude cerebral edema, which has a different pathophysiology.
**Option B:** This option may describe a treatment for HAPE, such as the use of nifedipine, but does not describe the condition itself.
**Option C:** This option may describe a risk factor for HAPE, such as a history of smoking, but does not describe the condition's pathophysiology.
**Clinical Pearl / High-Yield Fact**
A key clinical feature of HAPE is the presence of a "pericardial friction rub" on physical examination, which is due to the fluid leakage into the pleural space. Additionally, HAPE is more common in individuals with a history of rapid ascent to high altitude.
**Correct Answer: C.**