What can an excess of interstitial fluid impair?

An excess of interstitial fluid can significantly impair oxygen diffusion into the capillaries. In healthy lung function, oxygen moves from the alveoli into the blood within the capillaries through a thin membrane. When there is an accumulation of interstitial fluid, this fluid can create a barrier between the alveoli and the capillaries, reducing the efficiency of gas exchange. The excess fluid increases the distance that oxygen must diffuse, making it harder for adequate amounts to enter the bloodstream. This can lead to inadequate oxygen levels in the body and is often associated with various pulmonary conditions that increase interstitial fluid, such as pneumonia, pulmonary edema, or congestive heart failure.

Other options, while related to respiration and lung function, do not directly capture the primary issue caused by interstitial fluid accumulation as effectively as the impairment of oxygen diffusion does.