What spirometry reading is expected in a patient with chronic emphysema?

In chronic emphysema, a type of chronic obstructive pulmonary disease (COPD), there is a destruction of the alveoli and lung tissue, which leads to several characteristic changes in lung function. An expected finding in patients with this condition is an increased residual volume. This occurs due to air trapping, where patients are unable to fully exhale, leading to a larger amount of air remaining in the lungs after exhalation.

As the disease progresses, the loss of elastic recoil of the lung tissue interferes with the ability to expel air efficiently. Thus, the residual volume—representing the air left in the lungs after maximum exhalation—tends to be elevated. This increase is a direct consequence of the structural changes in the lung due to chronic emphysema.

Understanding this mechanism is crucial for interpreting pulmonary function tests and managing patients with emphysema effectively. In contrast, total lung capacity remains unchanged in emphysema, although other measurements like forced expiratory volume in one second (FEV1) may be decreased due to airway obstruction and while forced vital capacity (FVC) may be affected, it does not specifically indicate the unique air trapping characteristic of emphysema.