Emergency Medical Technician (EMT) Intermediate Practice Exam

In cases of pulmonary edema, diffusion is impaired primarily due to what condition?

1. Swelling of the pleura

2. Fluid-filled alveoli

3. Bronchoconstriction

4. Airway obstruction

The correct answer is: Fluid-filled alveoli

In cases of pulmonary edema, diffusion is impaired primarily due to fluid-filled alveoli. When fluid accumulates in the alveoli, the exchange of gases between the air in the alveoli and the blood in the surrounding capillaries is hindered. Under normal circumstances, oxygen from the alveoli diffuses into the blood and carbon dioxide diffuses out of the blood into the alveoli to be exhaled. However, the presence of fluid disrupts this process by creating a barrier that increases the distance that gases must travel, thus impeding their diffusion. The other conditions listed do not directly relate to the primary impairment of diffusion caused by pulmonary edema. Swelling of the pleura can affect lung mechanics but does not directly fill the alveoli with fluid. Bronchoconstriction can lead to airway constriction, impacting airflow but not the direct diffusion process at the alveolar level. Airway obstruction also affects airflow, but similarly does not fill the alveoli with fluid, thus not serving as the primary mechanism of impaired diffusion in pulmonary edema scenarios. Therefore, the presence of fluid in the alveoli is the key factor in this impairment.