How does an increase in altitude affect blood oxygen saturation?

An increase in altitude leads to a decrease in the partial pressure of oxygen in the atmosphere. As an individual ascends to higher altitudes, the lower atmospheric pressure results in a reduced amount of oxygen available for diffusion into the bloodstream at the alveolar level. Consequently, this reduces blood oxygen saturation levels. When blood oxygen saturation decreases significantly, this condition can lead to hypoxia, which is a deficiency of oxygen reaching tissues.

Understanding this concept is critical, particularly for those involved in aeromedical practices, as it highlights the physiological adaptations (or lack thereof) that occur in response to altitude changes. Individuals exposed to high altitudes may experience symptoms ranging from mild, such as fatigue and headaches, to severe, involving loss of consciousness or altitude sickness, all stemming from reduced oxygen availability.