The answer is not B because with interstitial fibrosis you have a decrease in the diffusing capacity because of the thickened alveolar membrane. The answer is not FRC because that will decrease in a restrictive lung disease such as fibrosis. FVC, RV, and TV are all expected to decrease.
I chose residual volume, but looking back, here's why its not (correct me if im wrong):
Restrictive lung disease is an issue with inspiring enough O2, not a problem with expiration (which is in obstructive lung disease like emphysema from floppy alveoli)
Also, a factor that influences A-a gradient is thickened membranes (decreased ability to diffuse across)
I think "Alveolar-arteriole PO2 difference" threw me off bc they didnt use the exact term of A-a gradient and I wasnt able to deduce that they're the same thing or felt like i was being tricked
Weird wording on the last sentence "Which of the following pulmonary function tests in this patient will most likely show a result greater than the predicted range?"
I mean, I was like this guy definitely has pulmonary fibrosis, so I'm predicting that his range of FVC, RV, FRC, TV, etc is low. It would be nice if it said 'greater than a normal patient'
I chose residual volume, but looking back, here's why its not (correct me if im wrong):
Restrictive lung disease is an issue with inspiring enough O2, not a problem with expiration (which is in obstructive lung disease like emphysema from floppy alveoli)
Also, a factor that influences A-a gradient is thickened membranes (decreased ability to diffuse across)
I think "Alveolar-arteriole PO2 difference" threw me off bc they didnt use the exact term of A-a gradient and I wasnt able to deduce that they're the same thing or felt like i was being tricked
submitted by โneonem(630)
This patient has pulmonary fibrosis, which causes a restrictive (not obstructive)-type disease. Since there was no occupational exposure, I'm assuming this is idiopathic pulmonary fibrosis. This causes thickened alveolar membranes, limiting gas diffusion. Therefore, eventually O2 won't be able to diffuse quickly enough into the blood across the alveolar-arterial membrane, resulting in a larger A-a difference. (I think there's normally a small A-a gradient, from 2-14 mm Hg, but when this gets too big, you get hypoxic)