Intensive Care Medicine (ICM) Practice Exam

Which pulmonary condition is characterized by reduced oxygen diffusion at the alveolar level?

1. Asthma

2. Pneumonia

3. Emphysema

4. Bronchitis

The correct answer is: Pneumonia

Pneumonia is characterized by inflammation of the lung tissue, specifically affecting the alveoli. This inflammation can lead to the filling of alveolar spaces with fluid, pus, or cells, which severely impairs the ability of oxygen to diffuse across the alveolar-capillary membrane. The presence of exudative fluid in the alveoli obstructs the normal gas exchange process, resulting in reduced oxygen diffusion into the bloodstream. In contrast, asthma primarily involves reversible airway obstruction and inflammation but does not typically affect the alveolar structure in the same manner as pneumonia. Emphysema, a type of chronic obstructive pulmonary disease (COPD), results in damage to the alveoli but leads primarily to a reduction in surface area for gas exchange, affecting diffusion indirectly. Bronchitis involves inflammation of the bronchi and primarily impacts airflow rather than oxygen diffusion across the alveoli. Therefore, pneumonia directly impairs oxygen diffusion at the alveolar level due to fluid accumulation and inflammatory processes, highlighting its characteristic effect on gas exchange.