The cause of death in HACE is brain herniation. Dexamethasone (see below) can be used to treat AMS and HACE, but, unlike acetazolamide, dexamethasone does not facilitate acclimatization and may give a false sense of security. It is an excellent rescue drug to assist in descent.55,56 If descent is not

possible, both oxygen and portable inflatable hyperbaric chambers (Figure 4) improve oxygen saturation and can be Inhibitors,research,lifescience,medical effective treatments for subjects with HACE or high-altitude pulmonary edema.57,58 Figure 4 Portable hyperbaric chamber. Inflatable hyperbaric chambers are often carried by trekking companies taking clients to altitude; the bags weigh about 6.5 kg and, when expanded, are cylindrical in shape and large enough to accommodate a person (Figure 4). By inflating Inhibitors,research,lifescience,medical the bag

with a foot pump, the effective altitude can be decreased as much as 1,500 meters (5,000 feet). The foot pump has to be used continuously while the person is in the bag to supply fresh oxygen and to flush out carbon dioxide. HIGH-ALTITUDE PULMONARY EDEMA High-altitude pulmonary edema (HAPE) is a potentially fatal consequence of rapid ascent to high altitude. Early diagnosis may be difficult Inhibitors,research,lifescience,medical since many of the early symptoms (shortness of selleck chemicals llc breath, tachypnea, tachycardia, reduced arterial saturation, fatigue, and cough) are often present in unaffected climbers at higher altitudes, particularly in cold, dry, or dusty environments. Distinguishing features of high-altitude pulmonary edema include incapacitating fatigue, dyspnea with minimal effort that advances Inhibitors,research,lifescience,medical to dyspnea at rest, orthopnea, and a dry non-productive cough progressing to a productive cough with pink frothy sputum due to hemoptysis. Fever may also accompany HAPE, and its presence does not imply infection; prompt administration of antibiotics

is not required unless other symptoms or a chest radiograph indicate pneumonia.59 The onset of HAPE is usually Inhibitors,research,lifescience,medical delayed and typically occurs 2–4 days after arrival at altitude; it is not uniformly preceded by AMS.14 HAPE is most common at altitudes many greater than 3,000 m,52 but HAPE can and does occur at lower altitudes. Over a 7-year period, 47 cases of HAPE were reported at a single Colorado ski resort with an elevation of 2,500 m.60 The pathogenesis of high-altitude pulmonary edema is still a subject for investigation; however, it is probably triggered by an increase in pulmonary artery pressure due to the normal pulmonary vasoconstriction induced by hypoxia. Patients with HAPE have an enhanced pulmonary reactivity to hypoxia, an exaggerated increase in pulmonary artery pressures, and are improved by pharmacological interventions that decrease pulmonary artery pressure.