Exposure to altitudes greater than 2500 m (8202 feet) without acclimatization can result in acute mountain sickness (AMS) and is characterized by headache, malaise, fatigue, sleep disturbance, and gastrointestinal complaints. This prospective observational study included 98 participants from the US Antarctic Program who did not use prophylactic acetazolamide before rapidly ascending to the Amundsen-Scott South Pole Station (∼3200 m) and was collected over 2 austral summer seasons in 2005–2006 and 2006–2007. Baseline questionnaires collected at McMurdo station (sea level) included the Lake Louise Symptom score and additional questions regarding physical symptoms related to AMS, medical history, current medications, lifestyle, exercise habits, and previous experience at high altitude. Age, sex, body mass index, blood pressure, heart rate, and oxygen saturation were also recorded. Blood draws were obtained at sea level 1 to 2 days before departure for the South Pole station. AMS symptom questionnaires were repeated by participants on the plane to Amundsen-Scott and for the first 7 days at 3200 m. Blood draws were repeated on day 3 of arrival to altitude. Of the 98 participants, 30 experienced AMS, defined as a Lake Louise Symptom score of greater than or equal to 3 along with a concurrent headache. Between the groups of those who experienced AMS and those who did not, statistically significant differences were present in several parameters including heart rate, blood pressure, sodium concentration, low-density lipoproteins, eosinophils, tumor-necrosis factor alpha, vascular endothelial growth factor, and dopamine. The authors found that total body water regulation and inflammation are key factors in AMS development. Although further research is necessary, the authors suggest that maintaining intravascular volume to minimize edema combined with the use of anti-inflammatory medications could help prevent development of AMS.
(BMJ Open. 2013;3:e64) MF Harrison, P Anderson, A Miller, K O’Malley, M Richert, J Johnson, BD Johnson. Prepared by Heather Beasley, University of Utah School of Medicine Medical Student, Salt Lake City, UT, USA.