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The Scientific World Journal
Volume 2013, Article ID 241569, 7 pages
http://dx.doi.org/10.1155/2013/241569
Review Article

Effects of High Altitude on Sleep and Respiratory System and Theirs Adaptations

1Department of Otolaryngology-Head and Neck Surgery, Istanbul Medeniyet University, Faculty of Medicine, 34100 Istanbul, Turkey
2Department of Otolaryngology-Head and Neck Surgery, Acibadem University, Faculty of Medicine, 34742 Istanbul, Turkey
3Department of Otolaryngology-Head and Neck Surgery, Osmangazi University, Faculty of Medicine, 26020 Eskisehir, Turkey
4Department of Otolaryngology-Head and Neck Surgery, Celal Bayar University, Faculty of Medicine, 45010 Manisa, Turkey
5Department of Otolaryngology-Head and Neck Surgery, Dumlupinar University, Faculty of Medicine, 43100 Kutahya, Turkey
6Sisli Etfal Training and Research Hospital, Department of Otolaryngology-Head and Neck Surgery, 34371 Istanbul, Turkey

Received 6 January 2013; Accepted 20 March 2013

Academic Editors: I. Ozcan, K. M. Ozcan, and A. Selcuk

Copyright © 2013 Turhan San et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

High-altitude (HA) environments have adverse effects on the normal functioning body of people accustomed to living at low altitudes because of the change in barometric pressure which causes decrease in the amount of oxygen leading to hypobaric hypoxia. Sustained exposure to hypoxia has adverse effects on body weight, muscle structure and exercise capacity, mental functioning, and sleep quality. The most important step of acclimatization is the hyperventilation which is achieved by hypoxic ventilatory response of the peripheral chemoreceptors. Hyperventilation results in increase in arterial carbondioxide concentration. Altitude also affects sleep and cardiac output, which is the other determinant of oxygen delivery. Upon initial exposure to HA, the resting pulse rate increases rapidly, but with acclimatization, heart rate and cardiac output tend to fall. Another important component that leads to decrease in cardiac output is the reduction in the stroke volume with acclimatization. During sleep at HA, the levels of CO2 in the blood can drop very low and this can switch off the drive to breathe. Only after the body senses a further drop in O2 levels breathing is started again. Periodic breathing is thought to result from instability in the control system through the hypoxic drive or the response to CO2.