How does Functional Residual Capacity (FRC) change in pulmonary fibrosis?

How does Functional Residual Capacity (FRC) change in pulmonary fibrosis?

• A. Increases
• B. Decreases
• C. Remains the same
• D. Fluctuates

Answer: (B)

Functional Residual Capacity (FRC) refers to the volume of air that remains in the lungs after a normal, passive exhalation. In conditions like pulmonary fibrosis, the lung tissue becomes stiff and less compliant due to the scarring process, making it harder for the lungs to expand during inhalation. Consequently, this decreased compliance alters lung volumes. In pulmonary fibrosis, the increase in lung stiffness leads to a reduction in total lung capacity, which includes a decrease in FRC. This occurs because the fibrotic changes restrict the ability of the lungs to hold air at the end of a normal exhalation, effectively lowering the FRC. As such, the lungs cannot accommodate as much air due to their compromised elasticity, which is why the correct answer is that FRC decreases in pulmonary fibrosis. In contrast, options suggesting that FRC increases or remains the same do not account for the restrictive effect of fibrosis on lung mechanics. Fluctuation is also not typical in this context, as fibrotic changes tend to cause a stable and consistent reduction in lung volumes rather than variability.

Functional Residual Capacity (FRC) refers to the volume of air that remains in the lungs after a normal, passive exhalation. In conditions like pulmonary fibrosis, the lung tissue becomes stiff and less compliant due to the scarring process, making it harder for the lungs to expand during inhalation. Consequently, this decreased compliance alters lung volumes.

In pulmonary fibrosis, the increase in lung stiffness leads to a reduction in total lung capacity, which includes a decrease in FRC. This occurs because the fibrotic changes restrict the ability of the lungs to hold air at the end of a normal exhalation, effectively lowering the FRC. As such, the lungs cannot accommodate as much air due to their compromised elasticity, which is why the correct answer is that FRC decreases in pulmonary fibrosis.

In contrast, options suggesting that FRC increases or remains the same do not account for the restrictive effect of fibrosis on lung mechanics. Fluctuation is also not typical in this context, as fibrotic changes tend to cause a stable and consistent reduction in lung volumes rather than variability.