If a patient has fluid in the lungs, what is the effect on gas exchange?

If a patient has fluid in the lungs, what is the effect on gas exchange?

• A. Increases gas exchange
• B. Decreases gas exchange because O2 cannot be exchanged
• C. No effect on gas exchange
• D. Increases diffusion distance

Answer: (B)

Fluid in the lungs creates a barrier and increases the distance oxygen must diffuse from the alveolar air into the blood. This extra distance slows or limits the transfer of oxygen across the alveolar-capillary membrane, so the blood becomes less oxygenated. While carbon dioxide diffuses more readily, the overall gas exchange is reduced because oxygen transfer is markedly impaired. In short, the presence of fluid lowers the efficiency of gas exchange by hindering oxygen diffusion.

Fluid in the lungs creates a barrier and increases the distance oxygen must diffuse from the alveolar air into the blood. This extra distance slows or limits the transfer of oxygen across the alveolar-capillary membrane, so the blood becomes less oxygenated. While carbon dioxide diffuses more readily, the overall gas exchange is reduced because oxygen transfer is markedly impaired. In short, the presence of fluid lowers the efficiency of gas exchange by hindering oxygen diffusion.