Erythropoietin in the Prevention of Acute Mountain Sickness

Overview

Acute mountain sickness (AMS) is a syndrome of nonspecific symptoms and is therefore subjective. The Lake Louise Consensus Group defined acute mountain sickness as the presence of headache in an unacclimatized person who has recently arrived at an altitude above 2,500 m plus the presence of one or more of the following: gastrointestinal symptoms (anorexia, nausea, or vomiting), insomnia, dizziness, and lassitude or fatigue. An increase in RBC mass is a natural feature of altitude acclimatization. Hypoxia-induced erythropoietin (EPO) secretion begins hours after ascent and stimulates bone marrow production of red blood cells, but this takes weeks to effect an increase in red cell mass . Therefore, it is feasible that EPO therapy weeks before altitude exposure decrease high altitude illness. In 1996, Young et al in U.S. Army Research Institute of Environmental Medicine (USARIEM) reported that autologous erythrocyte infusion did not ameliorate the decrement in maximal oxygen uptake at 4,300m altitude despite increasing arterial oxygen carrying capacity. On the basis of this report, USARIEM did not recommend use of recombinant EPO for altitude acclimatization. However, increases in erythrocyte count, hematocrit and hemoglobin associated with EPO therapy have been shown to decrease fatigue and increase work capacity and exercise tolerance. In addition, improvement in CNS function and cognitive ability has been noted with EPO therapy. Subjective benefits include improvement in sleep habits, tolerance to cold; decreased dyspnea, anginal symptoms and tachycardia and improved appetite, all of which are symptoms associated with high altitude illness. The investigators also reported improved muscle energy metabolism with EPO in dialysis patients, but not with RBC transfusion. In this study, the investigators will conduct a randomised controlled trial to assess the effect of EPO administration on AMS at an altitude of 4,130 m.