Alveolar Hypoventilation

A low A to A ratio is bad because that means there's a low percent of oxygen going through from alveoli to blood. Or if the A to A gradient is really big, well, that would just mean that like you have a ton of oxygen in the alveoli and why isn't it going over to the artery? And so when you look at those and they're a little bit more sensitive for alveolar hypoventilation, which is a big one. But again, yeah, it's kind of a Swiss cheese model. You're always going to end up with some holes in there. There's a really cool app called AA gradient that you can download.