A patient with pulmonary fibrosis experiences significantly reduced oxygen transfer from alveoli to blood. Why does supplemental oxygen via nasal cannula only partially alleviate the hypoxemia?

💡 Explanation

Pulmonary fibrosis increases alveolar membrane thickness, impairing gas exchange due to reduced diffusion capacity. The thicker membrane increases the diffusion distance for oxygen. Therefore, supplemental oxygen helps, but is limited by Fick's Law, rather than erythropoiesis or capillary transit time.

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