title: The Young Everest Study: effects of hypoxia at high altitude on cardiorespiratory function and general well-being in healthy children.
abstract: OBJECTIVE
  To assess the effect of altitude and acclimatisation on cardiorespiratory function and well-being in healthy children.
  
  
  METHODS
  A daily symptom diary, serial measurements of spirometry, end-tidal carbon dioxide (etCO(2)) and daytime and overnight pulse oximetry (SpO(2)), were undertaken at sea level and altitudes up to 3500 m in healthy children during a trekking holiday. SpO(2) at altitude was compared with that in flight and during acute hypoxic challenge (breathing 15% oxygen) at sea level.
  
  
  RESULTS
  Measurements were obtained in nine children aged 6-13 years (median 8). SpO(2) decreased significantly during the hypoxic challenge (difference -5%, 95% CI -6 to -3%, p<0.01) but remained above 90% in all children. There was a significant fall in daytime and overnight SpO(2) (95% CI -11.9 to -7.5% and -12 to -8, respectively) and etCO(2) (-8.5 to -4.5 mm Hg) as the children ascended to 3500 m. There was a significant increase in SpO(2) (95% CI 1.1 to 4.9%) and a further drop in etCO(2) (-5.9 to -0.8 mm Hg) after a week at altitude, etCO(2) being negatively correlated with SpO(2). There was no correlation between SpO(2) during hypoxic challenge, in flight or at altitude. Lung function remained within 7% of baseline in all but two children, in whom reductions of up to 23% in FVC and 16% FEV(1) were observed at altitude. The children generally remained well, but the Lake Louise scoring system was unreliable in this age group.
  
  
  CONCLUSIONS
  A wide range of physiological responses to altitude are evident in healthy children. This study should inform future larger studies in children to improve understanding of responses to hypoxia in health and disease.
authors.affiliation: Department of Paediatric Respiratory Medicine, Great Ormond Street Hospital for Children NHS Trust, London WC1N 3JH, UK. E.Scrase@ich.ucl.ac.uk
authors.forename: E
authors.initials: E
authors.lastname: Scrase
authors.forename: A
authors.initials: A
authors.lastname: Laverty
authors.forename: J C D
authors.initials: JC
authors.lastname: Gavlak
authors.forename: S
authors.initials: S
authors.lastname: Sonnappa
authors.forename: D Z H
authors.initials: DZ
authors.lastname: Levett
authors.forename: D
authors.initials: D
authors.lastname: Martin
authors.forename: M P W
authors.initials: MP
authors.lastname: Grocott
authors.forename: J
authors.initials: J
authors.lastname: Stocks
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000293:Adolescent; D000531:Altitude; D002648:Child; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D009051:Mountaineering / Q000502:physiology; D009390:Nepal; D010092:Oximetry; D010807:Physical Endurance / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology; D012129:Respiratory Function Tests; D013147:Spirometry; D014195:Travel