Which of the following statements is true about High Attitude Pulmonary Edema (HAPE)?

Answer is B (Associated with pulmonary vasoconstriction) Although the mechanism of high altitude pulmonary edema remains obscure most studies suggest pulmonary vasoconstriction (venconstriction or aeriolar constriction) as the prime mechanism. HAPE : High Altitude Pulmonary Edema This is a serious complication usually occruing at exposure to high altitude (>300m) in association with severe physical exercise and is classically seen in unacclametized healthy individuals. Pulmonary vasoconstriction has been suggested as the prime mechanism. "Studies have been conflicting, some suggesting pulmonary venous constriction and other indicating pulmonary aeriolar constriction as the prime mechanism."- Harrison May occur in both acclamatized and unacclamatized individuals "Well recognized in unacclamatized yet otherwise healthy persons." "Acclamatized high altitude natives also develop this syndrome upon return to high altitude after a relatively brief sojourn at low altitudes." - Harrison HAPE is exacerbated by exercise and is associated with high cardiac output. Increased cardiac output and pulmonary aerial pressures with exercise combined with hypoxic pulmonary aeriolar constriction which is more prominent in young persons may combine to make this an example of preaeriolar high pressure pulmonary edema.