Lecture 24 - Hypoxemia

Question 1

what are the 2 roles of oxygen in the body

Answer 1

1. generate ATP
2. partake in aerobic metabolism

Question 2

what is the normal PaO2

Answer 2

80-100mmHg

Question 3

hypoxic/hypoxia

Answer 3

insufficient oxygen levels

Question 4

hypoxemia

Answer 4

insufficient oxygen in the blood

Question 5

what are the 5 etiologies of hypoxemia

Answer 5

1. low inspired O2
2. hypoventilation
3. V/Q mismatch
4. anatomic shunt
5. diffusion impairment

Question 6

what are the potential causes of a decreased oxygen concentration

Answer 6

1. high altitude
2. anesthesia

Question 7

if PAO2 decreases, then PaO2 ____

Answer 7

decreases

Question 8

what are the 3 causes of hypoventilation (hypercapnia)

Answer 8

1. decreased central chemoreceptor sensitivity (depression secondary to anesthesia)
2. upper airway obstruction
3. neuromuscular weakness or dysfunction

Question 9

what is the difference between hypoventilation vs. V/Q mismatch

Answer 9

hypoventilation is in upper airway due to obstruction

V/Q mismatch occurs at the alveolar level

Question 10

V/Q abnormalities are caused by

Answer 10

1. dead space (V/Q > 1)
2. physiologic shunt (V/Q < 1)

Question 11

dead space has what effect on PaO2

Answer 11

decreases

Question 12

the physiologic shunt has what effect on PaO2? why?

Answer 12

decreases due to venous admixture

Question 13

describe a right-to-left shunt

Answer 13

congenital defect resulting in venous admixture at the ventricle level

pulmonary stenosis, RV hypertrophy, ventricular septal defect

Question 14

what would cause diffusion impairment

Answer 14

disease thickening respiratory membrane (cystic fibrosis)

Question 15

what is PAO2 used to predict

Answer 15

alveolar or arterial oxygen levels

Question 16

T/F: relative hypoxemia can occur ONLY with supplemental oxygen

Answer 16

TRUE