Hypoventilation

Question 1

Does a normal respiratory rate (RR) guarantee normal ventilation?

Answer 1

No

Question 2

Why can ventilation be abnormal despite a normal RR?

Answer 2

Because ventilation depends on both respiratory rate and tidal volume

Question 3

Does an increased RR always indicate hyperventilation?

Answer 3

No

Question 4

Why can increased RR fail to cause hyperventilation?

Answer 4

If tidal volume is small, minute ventilation may still be inadequate

Question 5

Does a decreased RR always indicate hypoventilation?

Answer 5

No

Question 6

Why can decreased RR still result in adequate ventilation?

Answer 6

Because tidal volume may be large enough to maintain ventilation

Question 7

best indicator of ventilation status?

Answer 7

PaCO₂ (PCO₂)

Question 8

Why is PaCO₂ the best marker of ventilation?

Answer 8

ecause CO₂ removal depends directly on alveolar ventilation

Question 9

Pa

Answer 9

arterial partial pressure

Question 10

low PaCO₂ indicate?

Answer 10

hyperventilation

Question 11

high PaCO₂ indicate?

Answer 11

hypoventilation

Question 12

two factors determine ventilation?

Answer 12

Tidal volume

Respiratory rate

Question 13

How does increased metabolism affect ventilation needs?

Answer 13

↑ metabolism → ↑ CO₂ production → ↑ ventilation required

Question 14

alveolar hypoventilation?

Answer 14

Inadequate alveolar ventilation relative to CO₂ production

Question 15

alveolar ventilation is determined by

Answer 15

deadspace volume, tidal volume, RR

Question 16

what determines ventilation adequacy?

Answer 16

Vt
f
Vd

Question 17

Vd

Answer 17

deadspace volume

Question 18

f

Answer 18

respiratory rate

Question 19

Vt

Answer 19

tidal volume

Question 20

What equation defines alveolar ventilation?

Answer 20

Question 21

How does increased dead space affect alveolar ventilation?

Answer 21

decreases alveolar ventilation - larger portion of each breath does not reach the alveoli

Question 22

most efficient way to increase alveolar ventilation?

Answer 22

Increasing tidal volume

Question 23

During exercising, animals manage increased demand of O2 and CO2production by increasing

Answer 23

minute ventilation

Question 24

minute ventilation

Answer 24

amount of air entering the lung in a min

Question 25

formula for minute ventilation

Answer 25

tidal v * frequency

Question 26

Why dead space is called “static”

Answer 26

cannot reduce anatomically so compensate by increasing tidal volume and respiratory rate

Question 27

formula for PiO2

Answer 27

Question 28

Patm =

Answer 28

760 mmHg

Question 29

Ph20 =

Answer 29

47 mmHg

Question 30

FiO2 =

Answer 30

0.21

Question 31

alveolar gas equation

Answer 31

Question 32

O2 consumed =

Answer 32

PaCO2/0.8

Question 33

Alveolar-arterial O2 diff (AaDO2) formula

Answer 33

Question 34

T/F We don’t assess AaDo2 in patients on supplemental O2

Answer 34

true

Question 35

PAO2

Answer 35

alveorlar

Question 36

normal A–aDO₂?

Answer 36

< 20 mmHG

Question 37

In which conditions is A–aDO₂ normal?

Answer 37

low PiO2 alveolar hypventilation

Question 38

Why is A–aDO₂ normal in low PiO₂?

Answer 38

Because both PAO₂ and PaO₂ decrease proportionally, so the difference remains unchanged

Question 39

Why is A–aDO₂ normal in alveolar hypoventilation?

Answer 39

Because PAO₂ is low and PaO₂ is low, but gas exchange is intact

Question 40

In which conditions is A–aDO₂ increased?

Answer 40

Diffusion impairment Ventilation/perfusion (V/Q) mismatch Right-to-left shunt

Question 41

Why does diffusion impairment increase A–aDO₂?

Answer 41

PAO₂ is normal but PaO₂ is low due to impaired oxygen transfer

Question 42

PAO₂ low + PaO₂ low → A–aDO₂ is?

Answer 42

normal

Question 43

PAO₂ normal + PaO₂ low → A–aDO₂ is?

Answer 43

increased

Question 44

when a patient is on supplemental O2, what is used instead of AaDO2

Answer 44

PaO2/FiO2 ratio

Question 45

T/F Alveolar hypoventilation always causes a rise in PaCO₂

Answer 45

true

Question 46

T/F Elevated PaCO₂ is pathognomonic for hypoventilation

Answer 46

true

Question 47

Pathognomonic

Answer 47

specifically diagnostic

Question 48

hypercapnia

Answer 48

CO2 buildup in blood

Question 49

can supplemental O2 relieve hypercapnia?

Answer 49

no; it can relieve hypoxemia but ventilation must be restored for hypercapnia

Question 50

what is common consequence of hypoventilation

Answer 50

respiratory acidosis

Question 51

T/F hypoventilation is commonly caused by disease outside the lungs

Answer 51

truee

Question 52

When there's alveolar hypoventilation, PaO2

Answer 52

decreases

Question 53

When there's alveolar hypoventilation, SO2

Answer 53

decreases - low % of O2 bound to hemoglobin

Question 54

When there's alveolar hypoventilation, AaDO2

Answer 54

normal

Question 55

When there's alveolar hypoventilation, PaCO2

Answer 55

increases

Question 56

When there's alveolar hypoventilation, pH

Answer 56

decreases

Question 57

When there's alveolar hypoventilation, HCO3-

Answer 57

increases

Question 58

hyperventilation has low or high PaCO2?

Answer 58

low PaCO2

Question 59

When does hyperventilation commonly occur?

Answer 59

As compensation for hypoxemia

Question 60

hypoxemia is caused by

Answer 60

Low PiO₂ (e.g., high altitude) Diffusion impairment Low V/Q mismatch

Question 61

purpose of a rebreathing bag in horses?

Answer 61

↑ Inspired CO₂ → ↑ PaCO₂ → stimulates ventilation

Question 62

primary regulator of ventilation?

Answer 62

H⁺ derived from CO₂