In emphysema, what happens to the residual volume (RV)?

In emphysema, the residual volume (RV) is indeed increased due to air trapping. This condition is characterized by the destruction of the alveolar walls, leading to the loss of elastic recoil of the lung. As a result, the ability to expel air from the lungs is impaired during exhalation. This impaired airflow can cause air to become trapped in the alveoli, leading to an accumulation of air and an increase in residual volume.

The increase in residual volume is closely associated with lung hyperinflation, as the lungs are unable to completely empty during exhalation, which is typical in emphysema. This hyperinflation, coupled with the loss of elastic recoil, further contributes to the increased RV.

In contrast, a decrease in residual volume would suggest improved lung function or effective airway clearance, neither of which applies in the context of emphysema. The residual volume would not remain unchanged, as the hallmark of the disease involves significant modifications in lung capacity and function. Thus, the correct understanding ties the increased residual volume to both air trapping and the characteristic lung hyperinflation seen in patients with emphysema.