Hypoxemia

Question 1

Definition

Answer 1

Low concentration of 02 in the lungs

Question 2

Aetiology

Answer 2

1-alveolar hypoventilation
2- V/Q mismatch
3- diffusion impairment
4-shunt

Question 3

Which is the most common cause of hypoxemia?

Answer 3

V/Q mismatch

Question 4

Alveolar hypoventilation

Answer 4

Hypoventilation increase PaC02 and decreases Pa02

Fall can easily be corrected by Fi02

Question 5

Shunt

Answer 5

Movement of blood from right side of heart to left bypassing the lungs
Increasing Fi02 has little effect

Question 6

V/Q mismatch

Answer 6

Related to focal hypoventilation

Question 7

Diffusion impairment

Answer 7

Dependant on the thickness of the membrane, Concentration gradient and surface area.
-Affects 02 a lot more than C02 as C02 is highly soluble
-Takes a long time for the blood an air to equilibrate
Normally takes 0.25 seconds to equilibrate
In hypoxemia takes 0.75s to equilibrate
Pa02 is normal at rest- reduced when exercising
Can be fixed by increasing Fi02

Rarely sole cause