Final answer:
The belief that SpO₂ automatically decreases with age over 70 is not true as a general rule. While age-related physiological changes and chronic health conditions can affect oxygen saturation, healthy aging individuals may maintain normal SpO₂ levels.
Step-by-step explanation:
The question of whether SpO₂ decreases with age (over 70) presents an opportunity to discuss hemoglobin affinity for oxygen. In general, it's a misconception that SpO₂, or oxygen saturation, automatically decreases significantly purely as a consequence of aging. However, various physiological changes, such as alterations in lung function, changes in respiratory muscles' strength, or the presence of chronic diseases, can impact this in individuals over 70.
Looking at the properties of hemoglobin, we know that its affinity for oxygen changes according to various factors such as pH, temperature, and the presence of carbon dioxide. For example, when the availability of oxygen decreases, which might happen due to environmental factors or lung conditions often associated with older age, hemoglobin's affinity for oxygen increases to facilitate the capture of more oxygen molecules (the Bohr effect). Yet, in healthy aging adults, without significant lung or cardiorespiratory diseases, oxygen saturation levels can remain within the normal range.
Therefore, to accurately respond to the statement that SpO₂ decreases with age (over 70), a comprehensive assessment that includes individual health status and environmental factors is required. However, the statement as a general rule is false since aging alone is not necessarily a direct cause of lower SpO₂ levels.