Which respiratory condition is characterized by limited lung expansion?

Pleural effusion is characterized by the accumulation of excess fluid in the pleural cavity, which surrounds the lungs. This fluid buildup exerts pressure on the lungs, limiting their ability to expand fully during inhalation. As a result, individuals with pleural effusion can experience difficulty breathing and reduced lung capacity.

In conditions like pneumonia, while lung function is impacted due to infection and inflammation, the primary issue is often related to lung consolidation rather than direct restriction of lung expansion. Asthma, on the other hand, is primarily an obstructive airway disease where inflammation and bronchoconstriction lead to difficulty with airflow but does not limit the lung's ability to expand mechanically in the same way. Chronic Obstructive Pulmonary Disease (COPD) includes emphysema and chronic bronchitis, which also affect airflow and can contribute to air trapping, but again, the restriction to lung expansion is not as direct as with pleural effusion.

Therefore, pleural effusion uniquely embodies the characteristic of limited lung expansion due to fluid accumulation, highlighting its role in respiratory compromise.