Abstract:

High altitude is associated with a decrease in atmospheric (i.e., barometric) pressure, which results in a decrease in the partial pressure of oxygen (O₂) and consequently leads to less O₂ availability (i.e., hypoxemia) in the blood. This has implications for those who work (i.e., mining), play (i.e., mountain climbing) or live at high altitude. Hypoxemia negatively impacts a number of physiological functions including sleep, cognition, and work capacity, which can endanger the safety and well-being of high-altitude workers. Over the past five years, we published a series of scientific papers reporting original data collected on volunteers who were naïve to high altitude and on perennial extreme high altitude workers. These studies were conducted at the ALMA (Atacama Large Millimeter Array) Observatory on the Chajnantor pleateau in the Atacama Desert in northern Chile. Acute exposure: Acute altitude exposure impairs reaction time, increases incidence of acute mountain sickness (AMS) symptoms, destabilizes breathing during sleep and impairs sleep quality. Similarly, some cognitive functions are impaired during acute altitude exposure volunteers who are naïve to high altitude. Further, the ability of the brain to regulate its blood supply and O₂ delivery (cerebral autoregulation) is also impaired during acute altitude exposure. Acclimatization: With a week of acclimatization, there is an improvement in cognitive functions, reaction time, cerebral autoregulation and a decrease in AMS symptoms. The improvement in reaction time, breathing stability, cerebral autoregulation and AMS symptoms appear to be long lasting. Repeated exposure: During repeated exposure there are no improvements in sleep and cognitive functions. However, the improvements in reaction time, breathing stability, cerebral autoregulation and AMS symptoms are carried over. In perennial extreme high altitude workers, the impairment of cognitive functions observed are associated with hypoxia. Similarly, the effects extreme high altitude are also reflected in blood biomarkers such as iron status, oxidative stress and anti-oxidant capacity. Conclusion: Acclimatization and repeated exposure to high altitude can minimize the negative consequences of hypoxia among high altitude workers. The health and safety of high altitude workers can be enhanced by a better understanding of the effects of high altitude on the underlying physiology of each individual (i.e., sleep, instability of breathing, cognition, O₂ content), and then tailoring personalized strategies and interventions to improve sleep, the instability of breathing, O₂ content in the blood and O₂ supplementation. Finally, the value of such an approach will help minimize nocturnal hypoxia and improve health and safety of the workers, and it will enhance the productivity and morale in the workplace. Furthermore, implementing research which aims to improve the condition of workers’ health and safety demonstrates great social corporate responsibility, reflecting a proactive and responsible attitude of the companies towards their workers. These findings are relevant to the mining sector with operations in extreme environments such as high altitudes and remote arctic regions (i.e., Northwest Territories and Nunavut) in Canada.

Acknowledgements

We acknowledge support from Alberta Innovates (MP), Canadian Institutes of Health Research (MJP, MP), NSERC CREATE (BRAIN CREATE; MJP, MP) and DISCOVERY (MJP) programs, and the Brenda Strafford Chair in Alzheimer Research (MJP).

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Dr. Marc Poulin