Gas Exchange (Sinclair)

Question 1

What are the 2 causes of hypoxemia present with a normal A-a difference?

Answer 1

1. Decreased PIO2 (altitude change)

2. Hypoventilation

Question 2

What are the 3 causes of hypoxemia present with a widened A-a difference?

Answer 2

1. Diffusion limitation
2. R-to-L shunt
3. Ventilation/Perfusion (V/Q) mismatch

Question 3

What does a normal A-s DO2 determine?

Answer 3

*

Question 4

What does an increased A-s DO2 determine?

Answer 4

*

Question 5

Lungs Functionally Divided into 2 ZONES:

Answer 5

conducting and respiratory

Question 6

Respiratory unit served by single terminal bronchiole

Answer 6

Acinus

Question 7

Several adjacent acini with incomplete septa

Answer 7

Lobule

Question 8

What is the calculation of partial pressure for inspired gas?

Answer 8

= (PB - PH2O) x FIGas

Question 9

VE (total ventilation) =

Answer 9

tidal vol x resp rate

Question 10

What air does not participate in gas exchange?

Answer 10

Air which remains in the Conducting airways at end inspiration (anatomic dead space)

Question 11

If a 500mL breath is taken, the amount of fresh gas delivered to alveoli will be:

Answer 11

500 - anat dead space

Question 12

Alveolar Ventilation =

Answer 12

Minute Ventilation - Dead space

Question 13

Alv Gas Equation =

CO2 Excretion

Answer 13

PACO2 = VCO2/VA (PB-47)

Question 14

Alv Gas Equation =

O2

Answer 14

PIO2-PAO2 = VO2/VA (PB-47)

Question 15

Alv gas equation =

complete

Answer 15

PAO2 = PIO2-(PaCO2/R)

Question 16

A-a difference (A-aDO2) is calculated by

Answer 16

subtracting PaO2 from PAO2

Question 17

Widened A-a difference signifies

Answer 17

presence of lung disease

Question 18

Normal A-a gradient signifies

Answer 18

no lung disease

Question 19

_____ oxygen tension is readily measured by ABG

Answer 19

arterial

Question 20

How does age affect arterial oxygen?

Answer 20

1. decreased oxygen transfer to blood due to declingin lung function
2. Arterial oxygen tension decreases with age

Question 21

Formula for normal A-a gradient

Answer 21

(age + 4)/4

Question 22

A-a difference (increases/decreases) with age because:

Answer 22

increases

alveolar oxygen tension remains the same which arterial oxygen tension declines

Question 23

Decreased oxygen tension in the circulating blood compared to normal

Answer 23

hypoxemia

Question 24

PaCO2 is a good measure of:

Answer 24

alveolar ventilation

Question 25

In terms of diffusion, hypoxemia only occurs if:

Answer 25

diffusion capacity severely decreased | transit time decreased

Question 26

Hypoxemia caused by _____ does NOT correct with increased FIO2

Answer 26

R to L shunt

Question 27

Ventilation and Perfusion are higher at the (apices/bases)

Answer 27

bases

Question 28

1. V/Q > 1 are called | 2. V/Q < 1 are called

Answer 28

1. dead space-like units | 2. shunt-like units

Question 29

T/F: Most lung diseases cause VQ mismatch

Answer 29

T

Question 30

Which causes of hypoxemia correct with O2

Answer 30

1. V/Q mismatch 2. diffusion limitation 3. decreased FIO2 4. hypoxemia?