a-a gradient

  1. M

    USMLE Perfusion limited, A-a gradient is not zero

    FA17 says that normal A-a gradient for oxygen is 10-15 mm Hg. Doesn't this mean that normally oxygen is diffusion limited? I am a little bit confused here, as multiple sources (including FA17) say that oxygen normally (in a healthy person at rest) is perfusion limited. If oxygen is really...