What factor best explains why pulmonary edema primarily affects oxygen uptake rather than CO2 elimination?

The factor that best explains why pulmonary edema primarily affects oxygen uptake rather than CO2 elimination is related to the difference in solubility of the gases in aqueous solution.

Oxygen and carbon dioxide behave differently when interacting with fluids in the body due to their varying solubility levels. Carbon dioxide is more soluble in water compared to oxygen, which means that at a given partial pressure, CO2 can diffuse more readily in aqueous environments. In the case of pulmonary edema, fluid accumulation in the alveoli increases the diffusion barrier primarily for oxygen, which has lower solubility and is thereby more affected by the presence of fluid.

When edema occurs, the fluid not only disrupts the normal air exchange but also increases the distance oxygen must diffuse into the bloodstream, significantly hampering its uptake. In contrast, carbon dioxide, being more soluble, can still diffuse out of the bloodstream into the alveoli even in the presence of fluid. Therefore, the impairment in oxygen uptake in the lungs due to pulmonary edema is significantly more pronounced than that of carbon dioxide elimination, underscoring the difference in their solubility in an aqueous environment.