True statement regarding Acute high altitude pulmonary edema ncludes

(B) Mandates immediate descent# High altitude pulmonary edema (HAPE) is a life-threatening form of non-cardiogenic pulmonary edema (fluid accumulation in the lungs) that occurs in otherwise healthy mountaineers at altitudes typically above 2,500 meters (8,200 ft).> Symptoms: at least two of: Difficulty in breathing (dyspnea) at rest Cough Weakness or decreased exercise performance Chest tightness or congestion> Signs: at least two of: Crackles or wheezing (while breathing) in at least one lung field Central cyanosis (blue skin color) Tachypnea (rapid shallow breathing) Tachycardia (rapid heartrate).> Mechanisms by which this shortage of oxygen causes HAPE are poorly understood, but two processes are believed to be important: Increased pulmonary arterial and capillary pressures (pulmonary hypertension) secondary to hypoxic pulmonary vasoconstriction. An idiopathic non-inflammatory increase in the permeability of the vascular endothelium.The standard and most important treatment is to descend to lower altitude as quickly as possible, preferably by at least 1000 metres.> Oxygen should also be given if possible. Symptoms tend to quickly improve with descent, but less severe symptoms may continue for several days.> Standard drug treatments for which there is strong clinical evidence are dexamethasone and nifedipine Phosphodiesterase inhibi- tors such as tadalafil are also effective but may worsen the headache of mountain sickness.