What lung disease is characterized by an increased total lung capacity (TLC)?

Emphysema is characterized by an increased total lung capacity (TLC) primarily due to the destruction of the alveolar walls, which leads to air trapping and a reduction in elastic recoil of the lungs. As the alveoli are damaged, they are less able to expel air effectively, resulting in air remaining in the lungs after expiration. This air trapping contributes to an increased TLC, as the lungs hold onto more air than they normally would.

In emphysema, the residual volume (RV), the amount of air left in the lungs after a forced expiration, is also elevated, further contributing to the increased TLC. The destruction of the elastic fibers and subsequent enlargement of air spaces means that the lungs become less efficient at exhaling air, which ultimately leads to hyperinflation.

Understanding why this is specific to emphysema rather than other conditions like pneumonia, chronic bronchitis, or asthma is essential. Pneumonia typically involves consolidation in the lungs and does not primarily increase lung capacity. Chronic bronchitis can lead to some air trapping but is more associated with increased mucus production and can also lead to an increase in TLC, but not as distinctly as in emphysema. Asthma, although it can cause airway obstruction and hyperinflation during