title: Effects of breathing control on cardiocirculatory modulation in Caucasian lowlanders and Himalayan Sherpas.
abstract: This study was performed to investigate the influence of breathing control on the autonomic cardiac regulation at high altitude in adapted and non-adapted awake subjects. We recorded electrocardiogram and pulse oximetry in 14 short-term acclimatized lowlanders and 14 Himalayan Sherpas during resting conditions at an altitude of 5,050 m. Spectrum analysis was performed on synchronized 15 min periods of R-R intervals and the oxygen saturation of arterial blood (SaO2). Despite mean SaO2 being similar in lowlanders and Himalayan Sherpas [78.5 (SD 7.0)% compared to 79.4 (SD5.8)%, respectively], fluctuations in SaO2 were significantly increased in lowlanders compared to Sherpas, thus indicating an unstable regulation of respiration control in lowlanders. Regression analysis demonstrated a significant relationship between spectrum power of SaO2 and the relative power of R-R intervals in the frequency band between 0.01 and 0.08 Hz in lowlanders, but not in Sherpas. Our results demonstrate differences in respiratory and autonomic cardiac control between non-adapted lowlanders and Himalayan high-altitude residents and indicate that unstable breathing control during chronic hypobaric hypoxia is significantly correlated with the autonomic cardiocirculatory regulation.
authors.affiliation: Department of Anaesthesiology, University Medical Centre Regensburg, University of Regensburg, Germany. keyl@rkananw1.ngate.uni-regensberg.de
authors.forename: C
authors.initials: C
authors.lastname: Keyl
authors.forename: A
authors.initials: A
authors.lastname: Schneider
authors.forename: R E
authors.initials: RE
authors.lastname: Greene
authors.forename: C
authors.initials: C
authors.lastname: Passino
authors.forename: G
authors.initials: G
authors.lastname: Spadacini
authors.forename: G
authors.initials: G
authors.lastname: Bandinelli
authors.forename: M
authors.initials: M
authors.lastname: Bonfichi
authors.forename: L
authors.initials: L
authors.lastname: Arcaini
authors.forename: L
authors.initials: L
authors.lastname: Malcovati
authors.forename: L
authors.initials: L
authors.lastname: Bernardi
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000328:Adult; D001158:Arteries; D002320:Cardiovascular Physiological Phenomena; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D009051:Mountaineering; D009390:Nepal / Q000208:ethnology; D010100:Oxygen / Q000097:blood; D012143:Respiratory Physiological Phenomena; D013997:Time Factors; D044465:White People
chemical_list: D010100:Oxygen