Though they have not formally been studied for the treatment of HAPE, phosphodiesterase type 5 inhibitors such as sildenafil and tadalafil are also effective and can be considered as add-on treatment if first-line therapy is not possible; however, they may worsen the headache of mountain sickness. There is no established role for the inhaled beta-agonist salmeterol, though its use can be considered.Dexamethasone has a potential role in HAPE, though there are currently no studies to support its effectiveness as treatment. However, as outlined in the 2014 WMS Practice Guidelines, its use is recommended for the treatment of people with concomitant HAPE and HACE at the treatment doses recommended for HACE alone. Additionally, they support its use in HAPE with neurologic symptoms or hypoxic encephalopathy that cannot be distinguished from HACE. Epidemiology
Rates of HAPE differs depending on altitude and speed of ascent. In general, there is about a 0.2 to 6 percent incidence at 4,500 metres (14,800 ft), and about 2 to 15 percent at 5,500 metres (18,000 ft). The higher incidence of 6% has been seen when climbers ascend at a rate > 600m/day. It has been reported that about 1 in 10,000 skiers who travel to moderate altitudes in Colorado develop HAPE; one study reported 150 cases over 39 months at a Colorado resort located at 2,928 metres (9,606 ft). About 1 in 50 climbers who ascended Denali [6,194 metres or 20,322 feet] developed pulmonary edema, and as high as 6% of climbers ascending rapidly in the Alps [4,559 metres or 14,957 feet].
Use of dexamethasone is currently indicated for the treatment of moderate-to-severe acute mountain sickness, as well as high-altitude cerebral edema. It has also been found to prevent HAPE, but its routine use is not yet recommended.Notably, each of these medications acts to block hypoxic pulmonary hypertension, lending evidence to the proposed pathophysiology of HAPE outlined above.It is recommended that those who go to high altitude avoid alcohol or sleeping medications. Treatment
The recommended first line treatment is descent to a lower altitude as quickly as possible, with symptomatic improvement seen in as few as 500 to 1,000 meters (1,640 feet to 3,281 feet). However, descent is not mandatory in people with mild HAPE and treatment with warming techniques, rest, and supplemental oxygen can improve symptoms. Giving oxygen at flow rates high enough to maintain an SpO2 at or above 90% is a fair substitute for descent. In the hospital setting, oxygen is generally given by nasal cannula or face mask for several hours until the person is able to maintain oxygen saturations above 90% while breathing the surrounding air. In remote settings where resources are scarce and descent is not feasible, a reasonable substitute can be the use of a portable hyperbaric chamber, which simulates descent, combined with additional oxygen and medications.As with prevention, the standard medication once a climber has developed HAPE is nifedipine, although its use is best in combination with and does not substitute for descent, hyperbaric therapy, or oxygen therapy.