Which is a feature of high altitude pulmonary edema-

HAPE is primarily a pulmonary problem and therefore is not necessarily preceded by HAPE develops within 2-4 days after arrival at high altitude; it rarely occurs after more than 4 or 5 days at the same altitude, probably because of remodeling and adaptation that render the pulmonary vasculature less susceptible to the effects of hypoxia. A rapid rate of ascent, a history of HAPE, respiratory tract infections, and cold environmental temperatures are risk factors. Men are more susceptible than women. People with abnormalities of the cardiopulmonary circulation leading to pulmonary hypeension--e.g., patent foramen ovale, mitral stenosis, primary pulmonaryhypeension, and unilateral absence of the pulmonary aery--are at increased risk of HAPE, even at moderate altitudes.High-altitude pulmonary edema often can be prevented by use of dexamethasone, calcium channel-blocking drugs, or long-acting inhaled b 2 -adrenergic agonists. Treatment includes descent from altitude, bed rest, oxygen, and, if feasible, inhaled nitric oxide; nifedipine may also be effective. ref:Harrison&;s principles of internal medicine,ed 18,pg no 4111