It should be the first diagnosis ruled out when sickness occurs while ascending to a high altitude. Prevention
HACE is generally preventable by ascending gradually with frequent rest days while climbing or trekking. Not ascending more than 1,000 metres (3,300 ft) daily and not sleeping at a greater height than 300 metres (980 ft) more than the previous night is recommended. The risk of developing HACE is diminished if acetazolamide or dexamethasone are administered. Generally, the use of acetazolamide is preferred, but dexamethasone can be used for prevention if there are side effects or contraindications. Some individuals are more susceptible to HACE than others, and physical fitness is not preventive. Age and sex do not by themselves affect vulnerability to HACE. Treatment
Patients with HACE should be brought to lower altitudes and provided supplemental oxygen, and rapid descent is sometimes needed to prevent mortality. Early recognition is important because as the condition progresses patients are unable to descend without assistance. Dexamethasone should also be administered, although it fails to ameliorate some symptoms that can be cured by descending to a lower altitude. It can also mask symptoms, and they sometimes resume upon discontinuation. Dexamethasones prevention of angiogenesis may explain why it treats HACE well. Three studies that examined how mice and rat brains react to hypoxia gave some credence to this idea.If available, supplemental oxygen can be used as an adjunctive therapy, or when descent is not possible.
FiO2 should be titrated to maintain arterial oxygen saturation of greater than 90%, bearing in mind that oxygen supply is often limited in high altitude clinics/environments.In addition to oxygen therapy, a portable hyperbaric chamber (Gamow bag) can by used as a temporary measure in the treatment of HACE. These devices simulate a decrease in altitude of up to 7000 ft, but they are resource intensive and symptoms will often return after discontinuation of the device. Portable hyperbaric chambers should not be used in place of descent or evacuation to definitive care.Diuretics may be helpful, but pose risks outside of a hospital environment. Sildenafil and tadalafil may help HACE, but there is little evidence of their efficacy. Theophylline is also theorized to help the condition.Although AMS is not life-threatening, HACE is usually fatal within 24 hours if untreated. Without treatment, the patient will enter a coma and then die. In some cases, patients have died within a few hours, and a few have survived for two days. Descriptions of fatal cases often involve climbers who continue ascending while experiencing the conditions symptoms. Prognosis
Recovery varies between days and weeks, but most recover in a few days. After the condition is successfully treated, it is possible for climbers to reascend. Dexamethesone should be discontinued, but continual acetazolamide is recommended. In one study, it took patients between one week and one month to display a normal CT scan following HACE.