Matching Ventilaton and Perfusion

Question 1

The alveolar-arterial O2 difference is normally about 10mmHg. What two factors account for this difference?

Answer 1

1. Normal Shunts (6mmHg)

2. Mismatched ventilation/perfusion (4mmHg)

Question 2

What are the 4 causes of hypoxemia?

Answer 2

1. Hypoventilation
2. Shunts
3. Diffusion limitation
4. V/P imbalance

Question 3

How can you fix hypoxemia caused by hypoventilation?

Answer 3

Give O2 (100%)

Question 4

How can you fix hypoxemia caused by a diffusion limitation.

Answer 4

Give O2 (100%)

Question 5

Why do shunts occur in the pulmonary circulation?

Answer 5

Not all the blood vessels in the pulmonary circulation come in contact with alveolar for gas exchange to occur. If hypoxemia occurs, providing O2 (100%) will not fix the issue.

Question 6

Where is the ventilation perfusion ratio (V/Q) the highest and lowest in the lungs?

Answer 6

Highest: apex
Lowest: base

however, ventilation is highest at the base and perfusion is highest at the base

Question 7

Where in the lungs is the alveolar concentration of oxygen the highest?

Answer 7

Apex
-inspired air contains a high amount of O2 and very little perfusion means little gas exchange occurs to remove O2 from the alveoli