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Rieger, Mathew Grant

University of British Columbia

Important changes to oxygen sensing and delivery pathways occur between infancy and adulthood, but little is known about the function of these pathways during childhood. Considering increases in the popularity of high-altitude travel and recreation among families, it is unknown whether children respond and acclimatize to altitude in a similar fashion as adults, which may have implications for safety and recommendations for high altitude travel. The aim of this dissertation was to describe ventilatory, cerebrovascular, and cardiopulmonary acclimatization to high altitude in children and adults, and further describe similar processes within children native to high altitude. Study 1 provides an assessment of respiratory and cerebrovascular responses to exercise in Sherpa children living at 3800 m, demonstrating that cerebral blood flow velocity (CBFv, transcranial Doppler ultrasound) responses to exercise were not different between children native to high altitude, and lowland children at low altitude. Study 2 investigated changes in resting ventilation (VE), cerebral blood flow (CBF; duplex ultrasound), and pulmonary artery systolic pressure (PASP; echocardiography) with altitude and found that CBF and PASP changed similarly at 3000 m and 3800 m between children and adults, but the threshold for hypoxic hyperventilation was lower in children. Study 3 investigated changes in VE and CBF velocity (CBFv) during exercise during acclimatization to high altitude and found that CBFv during exercise was augmented in children on day 2 at 3800 m, but not on day 4, and was unchanged in adults at altitude. In study #4, we assessed symptoms of acute mountain sickness (AMS) and changes in body composition in children and adults across 7 days at 3000-3800 m. Among children and adults who developed AMS, the severity of symptoms was greater in children. Weight loss occurred sooner in children than adults, and children lost a greater proportion of total body water. These findings collectively reveal subtle differences in ventilatory and cerebrovascular acclimatization processes between children and adults but highlight a general stability of physiological responses during prolonged altitude exposure. An in-depth understanding of how children are impacted by hypoxia is critical to the advancement of high-altitude travel and health guidelines for families.

Text

2022-09-29

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/82794

Kinesiology

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/