Acclimatization Practices of High-Altitude Recreationalists

Abstract

Acute mountain sickness (AMS) will occur if ascent to high altitude is rapid. Any type of travel to altitudes around 2500 m (8000 feet) is associated with an increased risk of AMS. Prevention of AMS through acclimatization procedures such as gradual ascent and pharmacologic agents that aid in the body’s accommodation to the hypobaric hypoxia resulting from high altitude exposure are key strategies. Forty percent of South Pole Station scientists and support staff during the 2006 and 2007 summer deployments chose to defer acclimatization medications before rapid ascent from McMurdo Station at sea level to the high altitude polar plateau at 2835 m (9300 feet), placing them at risk for having AMS (Anderson et al, 2011). Medical evacuation due to AMS is resource intensive and life-threatening to the person and to the rescue team. It also results in unsuccessful job performance for the person, precluding future polar plateau and frequently Antarctic deployment. The rationale and reasons for deferment of acclimatization guidelines is unknown. A convenience sample consisted of 120 volunteer high altitude recreationalists or backpackers, 18 years of age or older. A questionnaire was completed by subjects that included demographic information such as age, sex, altitude of residence, means of transport to calculate the rate of ascent, and the number of hours taken to acclimatize to the altitude at the trailhead. Acclimatization prophylaxis activities were documented, including the use of medications and personal home remedies. Baseline vital signs, height, weight, and body mass index were recorded for each subject. The instrument queried the volunteer about the existence of current AMS symptoms by completion of a Lake Louise Symptom Score questionnaire. Despite recent Wilderness Medical Society (WMS) recommendations (Luks et al, 2010) stressing gradual ascent and medication prophylaxis for the prevention of AMS, the majority (55%) of subjects (n = 66) did not perceive the need for medications. Only 3 subjects (2.5%) were taking acetazolamide and only 4% had consulted a health professional before their high altitude sojourn. Sixty-one percent of the subjects took less than 24 hours to ascend to 9300 feet to begin their journey. Forty percent of the respondents camped at the trailhead or above 6800 feet the night before their departure, and 7 subjects (6%) took hikes to enhance acclimatization the day before their departure. Many subjects were veteran backpackers and reported their acclimatization symptoms could be controlled with hydration (12%), adequate rest, and anti-inflammatory drugs (40%) to control headaches, joint pain, and AMS symptoms. The general consensus was to “suffer through” any symptoms. Twelve subjects (10%) were unaware that acclimatization was a recommendation for ascent to altitude. The dissemination of accurate information regarding acclimatization to high altitude is paramount for the prevention of AMS, not just for the polar explorer but also for the high altitude recreationalist. Being aware of the subtleties and risks of AMS, as well as embracing acclimatization guidelines as a primary prevention strategy of AMS, will bode well for all high mountain travelers as well as for the healthcare providers who inform them.