ABSTRACT
BACKGROUND: The occurrence and severity of acute high-altitude disease(AHAD) are determined by the speed entering the highland, the altitude of highland and seasons. The association between obesity and AHAD has not been fully investigated.OBJECTIVE: To investigate the association between obesity and acute high-altitude in people exposed rapidly to the highland.DESIGN: Comparative observation.SETTING: Department of Cardiology, General Hospital of Chinese PLA and Department of Cardiology, Tibetan General Hospital of Chinese PLA.PARTICIPANTS: The experiment was conducted at the Department of Cardiology, General Hospital of Tibetan Military Area Command of Chinese PLA in August 2006. Totally 82 Henan subjects aged 28-45 years were selected from the male workers constructing the Qinghai-Tibet Railway and their managers with acute high-altitude exposure. They had never been to the highland before, and all agreed to the detection.METHODS: ①Every subject completed the AHAD self-report questionnaire at sea level and 12 hours and 24 hours after ascending high-altitude. The items in the questionnaire included symptoms of headache, gastrointestinal symptoms,fatigue or weakness, dizziness, and insomnia. Each symptom was graded from 0-3 with 0 as no symptoms, 1 as mild symptoms, 2 as moderate symptoms, and 3 as severe symptoms and a total score of 15. A score of 4 or more could by identified as AHAD. ②The height and body mass were measured to calculate the body mass (BMI). Those with BMI≥28 kg/m2 served as the obesity group [n =39, mean age (35±8) years], and those with BMI of 18.5-23.9 kg/m2 as the normal body mass group [n =43, mean age (35±8) years]. ③Arterial blood was taken to evaluate arterial oxygen saturation (SO2), arterial oxygen pressure (PaO2) and arterial carbon dioxide pressure (PaCO2) at baseline and 24 hours after ascending high-altitude. ④The measurement data was compared by t test.MAIN OUTCOME MEASURES: BMI, vital capacity of lungs, SO2, PaO2 and PaCO2 levels of obese and normal people.RESULTS: Totally 39 obese people and 43 normal people were involved in the result analysis. ①AHAD score: No symptom was reported at sea level in all participants (scored 0), but the AHAD scores in the obesity group were significantly higher than those in normal group 12-hour and 24-hour after ascending high-altitude. ②Blood gas analysis:At sea level, there were no statistical differences in the levels of SO2, PaO2, and PaCO2 between two groups (P ＞ 0.05).But 24 hours after ascending high-altitude, SO2 and PaO2 of the obesity group were much lower than in the normal group (P＜ 0.01), and PaCO2 was significantly higher than in the normal group (P＜ 0.01).CONCLUSION: Obese men are more vulnerable to high-altitude hypoxia than people with normal body mass. Obesity is an important risk factor for the development of acute high-altitude disease.