title: Relationship between arterial oxygen saturation and heart rate variability at high altitudes.
abstract: Autonomic nervous systems have important roles for survival of victims under hypobaric hypoxic condition. In the present study, we assessed the correlation between arterial oxygen saturation (Sp O 2 ) and heart rate variability (HRV) to identify the autonomic nervous responsiveness among trekkers at high altitude (n = 21). HRV was analyzed by the maximum entropy method. Sp O 2 among subjects at 3456 m (495 mm Hg) was 80% +/- 5% (mean +/- SD; range, 69%-93%). Sp O 2 and percentile entropy, and Sp O 2 and low-frequency variability, had positive correlation ( r = 0.455 and 0.518, respectively). Sp O 2 value among subjects with mountain sickness symptoms was not different from that among subjects without the symptoms. In conclusion, autonomic responses among high-altitude trekkers may be blunted under hypobaric hypoxic conditions. Deterioration of autonomic function measured by HRV might be more sensitive to hypoxia than clinical symptoms at high altitudes.
authors.affiliation: Department of Anesthesiology, Gunma University School of Medicine, Maebashi 371-8511, Japan. shigerus@showa.gunma-u.ac.jp
authors.forename: Shigeru
authors.initials: S
authors.lastname: Saito
authors.forename: Kyoko
authors.initials: K
authors.lastname: Tanobe
authors.forename: Makiko
authors.initials: M
authors.lastname: Yamada
authors.forename: Fumio
authors.initials: F
authors.lastname: Nishihara
mesh_terms: D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000097:blood / Q000503:physiopathology; D001158:Arteries; D001342:Autonomic Nervous System Diseases / Q000097:blood* / Q000503:physiopathology; D001784:Blood Gas Analysis; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D000860:Hypoxia / Q000097:blood* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D012016:Reference Values
chemical_list: D010100:Oxygen