pulmonary I

Question 1

What is a normal A-a gradient?

Answer 1

5-15 mmHg

Question 2

What conditions cause an increased A-a gradient?

Answer 2

(ie big difference between the pressure of O2 in the lungs vs in the arteries)
pulmonary embolism, pulmonary edema, right-to-left vascular shunts

Question 3

Under what conditions might you see a false-normal A-a gradient?

Answer 3

-hypoventilation, high altitude

Question 4

How can you calculate the A-a gradient?

Answer 4

1. PaO2- measured directly from an ABG
2. PAO2- can’t be measured directly. roughly, on room air, you multiply the atmospheric air pressure by the FiO2, and then subtract the PaCO2/0.8.
   On room air at sea level, this translates to 150-(PaCO2/0.8)
3. A-a gradient: 150-(PaCO2/0.8)-PaO2
   normal: 5-15

Question 5

What is are normal PFTs?

Answer 5

-Basically, FEV1/FVC ration