CHEST Guidelines-Smoothing-Out-the-Peaks-and-Valleys-of-High-Altitu

Smoothing-Out-the-Peaks-and-Valleys-of-High-Altitu

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The article explores sleep-disordered breathing (SDB), specifically obstructive sleep apnea (OSA), in individuals living at high altitudes (highlanders). SDB is prevalent among highlanders, with up to 30% experiencing sleep apnea symptoms, characterized by a unique pattern of intermittent and sustained hypoxemia due to high altitudes. Traditionally, supplemental oxygen has been studied in lowlanders with OSA, showing limited impact on reducing the apnea-hypopnea index (AHI). However, the effects on highlanders were uncertain until a study by Tan et al. investigated this further.<br /><br />Tan and colleagues conducted a randomized crossover trial with Tibetan men living at 3,200 meters for over a decade, diagnosed with severe OSA. The study discovered that a night of supplemental oxygen significantly reduced the severity of sleep apnea—with a noteworthy drop in the AHI by approximately 18.9 events per hour and a considerable decrease in hypoxemia. Oxygen supplementation also improved morning heart rates and showed a trend toward reduced blood pressure.<br /><br />Despite promising results, the study had limitations such as the short duration of oxygen application and a selection bias towards male participants with obstructive sleep apnea. Central sleep apnea and the different responses of women to supplemental oxygen were not assessed. The research hints that supplemental oxygen possibly alleviates OSA in highlanders by modulating ventilatory response, or 'loop gain,' to hypoxia.<br /><br />Further research is crucial to determine the long-term effects of supplemental oxygen and its impacts on other health outcomes in highlanders. Challenges in applying these findings to broader, often low-income high-altitude populations without easy access to electric oxygen concentrators remain significant. Understanding the genetic factors and hypoxemia patterns could also unveil new insights into SDB and chronic conditions affected by hypoxia.

Keywords

Sleep-disordered breathing

Obstructive sleep apnea

High altitudes

Supplemental oxygen

Apnea-hypopnea index

Hypoxemia

Tibetan highlanders

Ventilatory response

Genetic factors

Chronic hypoxia