What is the expected effect of aging on arterial PO2 during pulmonary function tests?

As individuals age, several physiological changes occur in the respiratory system, impacting gas exchange and pulmonary function. One significant effect of aging is a gradual decline in lung function, characterized by a decrease in elastic recoil of the lung tissue and an increase in airspace size, which results in a ventilation-perfusion mismatch.

Additionally, the aging process is associated with a decrease in the diffusion capacity of the lungs. This is due, in part, to the reduction of alveolar surface area and inefficient gas exchange. As a result, the efficiency of oxygen uptake into the blood diminishes, which typically leads to a lower arterial partial pressure of oxygen (PO2).

Thus, during pulmonary function tests, the expected effect of aging is a decreased arterial PO2, reflecting the cumulative impact of these physiological changes on oxygenation and respiratory health.