Tai-Yi Hsu1, Yi-Ming Weng, Yu-Hui Chiu, Wen-Cheng Li, Pang-Yen Chen, Shih-Hao Wang, Kuo-Feng Huang, Wei-Fong Kao, Te-Fa Chiu, Jih-Chang Chen. 1. *Department of Emergency Medicine, Chang Gung Memorial Hospital, Chiayi, Taiwan; †Chang Gung University College of Medicine, Taoyuan, Taiwan; ‡Department of Emergency Medicine, Chang Gung Memorial Hospital, Linkou, Taiwan; §Department of Emergency Medicine, Mackay Memorial Hospital, Taipei, Taiwan; ¶Institute of Environmental and Occupational Health Sciences, National Yang-Ming University School of Medicine, Taipei, Taiwan; ‖Department of Emergency, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; **Department of Occupation Medicine, Chang-Gung Memorial Hospital, Keelung, Taiwan; ††Department of Emergency Medicine, Taipei Medical University Hospital, Taipei, Taiwan; ‡‡Department of Physical Education, National Taitung University, Taitung, Taiwan; and §§Department of Emergency Medicine, Taiwan Adventist Hospital, Taipei, Taiwan.
Abstract
OBJECTIVE: To examine the effect of ascent rate on the induction of acute mountain sickness (AMS) in young adults during a climb to Jiaming Lake (3350 m) in Taiwan. DESIGN: Prospective, nonrandomized. SETTING: Climb from 2370 to 3350 m. PARTICIPANTS: Young adults (aged 18 to 26 years) (N = 91) chose to participate in either the fast ascent (3 days; n = 43) or slow ascent (4 days; n = 48) group (1 and 2). ASSESSMENT OF RISK FACTORS: Two criteria were used to define AMS. A Lake Louise score ≥3 and Lake Louise criteria [in the setting of a recent gain in altitude, the presence of headache and at least 1 of gastrointestinal discomfort (anorexia, nausea, or vomiting), fatigue or weakness, dizziness or lightheadedness, or difficulty sleeping]. MAIN OUTCOME MEASURES: Heart rate, blood oxygen saturation (SaO2), and symptoms of AMS were monitored each morning and evening. RESULTS: Baseline characteristics were similar between groups, except for significant differences in history of alcohol consumption (P = 0.009) and climbing experience above 3000 m (P < 0.001). The incidence of AMS was not associated with the rate of ascent. Acute mountain sickness was most prevalent in group 1 on day 2 in the evening and in group 2 on day 3 in the evening. In both groups, AMS correlated with the initial reduction in SaO2. Body mass index (BMI) >24 kg/m was identified as a significant risk factor for AMS. CONCLUSIONS: The development of AMS was closely associated with an initial reduction in SaO2. A BMI >24 kg/m also contributed to the occurrence of AMS. CLINICAL RELEVANCE: These findings indicate that factors other than ascent rate should be considered when trying to ameliorate the risk of AMS.
OBJECTIVE: To examine the effect of ascent rate on the induction of acute mountain sickness (AMS) in young adults during a climb to Jiaming Lake (3350 m) in Taiwan. DESIGN: Prospective, nonrandomized. SETTING: Climb from 2370 to 3350 m. PARTICIPANTS: Young adults (aged 18 to 26 years) (N = 91) chose to participate in either the fast ascent (3 days; n = 43) or slow ascent (4 days; n = 48) group (1 and 2). ASSESSMENT OF RISK FACTORS: Two criteria were used to define AMS. A Lake Louise score ≥3 and Lake Louise criteria [in the setting of a recent gain in altitude, the presence of headache and at least 1 of gastrointestinal discomfort (anorexia, nausea, or vomiting), fatigue or weakness, dizziness or lightheadedness, or difficulty sleeping]. MAIN OUTCOME MEASURES: Heart rate, blood oxygen saturation (SaO2), and symptoms of AMS were monitored each morning and evening. RESULTS: Baseline characteristics were similar between groups, except for significant differences in history of alcohol consumption (P = 0.009) and climbing experience above 3000 m (P < 0.001). The incidence of AMS was not associated with the rate of ascent. Acute mountain sickness was most prevalent in group 1 on day 2 in the evening and in group 2 on day 3 in the evening. In both groups, AMS correlated with the initial reduction in SaO2. Body mass index (BMI) >24 kg/m was identified as a significant risk factor for AMS. CONCLUSIONS: The development of AMS was closely associated with an initial reduction in SaO2. A BMI >24 kg/m also contributed to the occurrence of AMS. CLINICAL RELEVANCE: These findings indicate that factors other than ascent rate should be considered when trying to ameliorate the risk of AMS.