Alveolar-Blood Gas Exchange

Question 1

Difference between respiratory quotient (RQ) and respiratory exchange ratio (RER)?

Answer 1

• RQ: ratio CO2 production/O2 consumption at cellular level
• RER: ratio CO2 output/O2 uptake in lung

*equal at steady state

Question 2

What do you use to evaluate the hypoxemia?

Answer 2

Alveolar arterial gradient of oxygen (A-a)

Question 3

When may the PO2 gradient across the alveolar membrane increase?

Answer 3

Helps to compensate a structural problem

Question 4

Unique substance that is diffusion-limited. Which is its use?

Answer 4

• Carbon monoxide
• to measure difussing capacity of the lung (DLCO)

*index of the lung’s structural features