Catherine Mary Hill1,2, Ana Baya3, Johanna Gavlak2,4, Annette Carroll5, Kate Heathcote6, Dagmara Dimitriou7, Veline L'Esperance8, Rebecca Webster9, John Holloway10, Javier Virues-Ortega11, Fenella Jane Kirkham1,2,4, Romola Starr Bucks12, Alexandra Marie Hogan13,14. 1. Division of Clinical Experimental Sciences, Faculty of Medicine, University of Southampton, UK. 2. Southampton Children's Hospital, Southampton, UK. 3. Department of Psychology, Universidad Privada de Santa Cruz de la Sierra, Santa Cruz - Bolivia. 4. Neurosciences Unit, UCL Institute of Child Health, UK. 5. Sleep Disorders Unit, Canberra Hospital, Australia. 6. Department of Otolaryngology, Poole General Hospital, UK. 7. University College London, Institute of Education, UK. 8. Department of Primary Care and Population Health, Kings College London, UK. 9. Laboratory for Cancer Medicine, Harry Perkins Institute of Medical Research and University of Western Australia Centre for Medical Research, Perth, Australia. 10. Division of Human Development and Health. Faculty of Medicine, University of Southampton, UK. 11. School of Psychology, Faculty of Science, The University of Auckland, New Zealand. 12. School of Psychology, University of Western Australia, Perth, Australia. 13. Cognitive Neuroscience & Psychiatry, UCL Institute of Child Health, UK. 14. North Central London School of Anaesthesia, London, UK.
Abstract
STUDY OBJECTIVES: Physiological adaptation to high altitude hypoxia may be impaired in Andeans with significant European ancestry. The respiratory 'burden' of sleep may challenge adaptation, leading to relative nocturnal hypoxia. Developmental aspects of sleep-related breathing in high-altitude native children have not previously been reported. We aimed to determine the influence of development on diurnal-nocturnal oxyhemoglobin differences in children living at high altitude. METHODS: This was a cross-sectional, observational study. Seventy-five healthy Bolivian children aged 6 mo to 17 y, native to low altitude (500 m), moderate high altitude (2,500 m), and high altitude (3,700 m) were recruited. Daytime resting pulse oximetry was compared to overnight recordings using Masimo radical oximeters. Genetic ancestry was determined from DNA samples. RESULTS: Children had mixed European/Amerindian ancestry, with no significant differences between altitudes. Sixty-two participants had ≥ 5 h of nocturnal, artifact-free data. As predicted, diurnal mean oxyhemoglobin saturation decreased across altitudes (infants and children, both P < 0.001), with lowest diurnal values at high altitude in infants. At high altitude, there was a greater drop in nocturnal mean oxyhemoglobin saturation (infants, P < 0.001; children, P = 0.039) and an increase in variability (all P ≤ 0.001) compared to low altitude. Importantly, diurnal to nocturnal altitude differences diminished (P = 0.036), from infancy to childhood, with no further change during adolescence. CONCLUSIONS: Physiological adaptation to high-altitude living in native Andeans is unlikely to compensate for the significant differences we observed between diurnal and nocturnal oxyhemoglobin saturation, most marked in infancy. This vulnerability to sleep-related hypoxia in early childhood has potential lifespan implications. Future studies should characterize the sleep- related respiratory physiology underpinning our observations.
STUDY OBJECTIVES: Physiological adaptation to high altitude hypoxia may be impaired in Andeans with significant European ancestry. The respiratory 'burden' of sleep may challenge adaptation, leading to relative nocturnal hypoxia. Developmental aspects of sleep-related breathing in high-altitude native children have not previously been reported. We aimed to determine the influence of development on diurnal-nocturnal oxyhemoglobin differences in children living at high altitude. METHODS: This was a cross-sectional, observational study. Seventy-five healthy Bolivian children aged 6 mo to 17 y, native to low altitude (500 m), moderate high altitude (2,500 m), and high altitude (3,700 m) were recruited. Daytime resting pulse oximetry was compared to overnight recordings using Masimo radical oximeters. Genetic ancestry was determined from DNA samples. RESULTS:Children had mixed European/Amerindian ancestry, with no significant differences between altitudes. Sixty-two participants had ≥ 5 h of nocturnal, artifact-free data. As predicted, diurnal mean oxyhemoglobin saturation decreased across altitudes (infants and children, both P < 0.001), with lowest diurnal values at high altitude in infants. At high altitude, there was a greater drop in nocturnal mean oxyhemoglobin saturation (infants, P < 0.001; children, P = 0.039) and an increase in variability (all P ≤ 0.001) compared to low altitude. Importantly, diurnal to nocturnal altitude differences diminished (P = 0.036), from infancy to childhood, with no further change during adolescence. CONCLUSIONS: Physiological adaptation to high-altitude living in native Andeans is unlikely to compensate for the significant differences we observed between diurnal and nocturnal oxyhemoglobin saturation, most marked in infancy. This vulnerability to sleep-related hypoxia in early childhood has potential lifespan implications. Future studies should characterize the sleep- related respiratory physiology underpinning our observations.
Authors: C M Beall; L A Almasy; J Blangero; S Williams-Blangero; G M Brittenham; K P Strohl; M J Decker; E Vargas; M Villena; R Soria; A M Alarcon; C Gonzales Journal: Am J Phys Anthropol Date: 1999-01 Impact factor: 2.868
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