Ventilation

Question 1

Ratio between alveolar ventilation and pulmonary blood flow

Answer 1

~1:1

Alveolar ventilation = 5.25 L/min

Pulm blood = 5L/min

Question 2

Tidal volume #

Answer 2

500 mL

Question 3

Anatomic dead space volume

Answer 3

150 mL (1mL per 1lb)

Question 4

Alveolar gas volume

Answer 4

3L

Question 5

Pulmonary capillary blood volume

Answer 5

70 mL

Question 6

Total ventilation #

Answer 6

7.5 L/min

Question 7

Frequency

Answer 7

15/min

Question 8

Total lung capacity (TLC or Vt) = ?

Answer 8

Vital capacity (VC) + Residual Volume (RV)

Inspiratory Capacity (IC) + Functional Residual Capacity (FRC)

Insp reserve volume (IRV) + Tidal volume (TV) + Exp reserve volume (ERV) + residual volume (RV)

Question 9

Vital capacity =

Answer 9

Max inspiration - max expiration

Question 10

Tital volume

Answer 10

Under normal/rest conditions

Question 11

Resting volume

Answer 11

After expiration during rest

Question 12

Total ventilation =

Answer 12

Tidal volume x respiratory rate

Normal = 500mL x 15breathes/min

= 7,500mL/min

Question 13

Alveolar ventilation

Answer 13

Since anatomic dead space is about 150mL…

Alveolar ventilation = (500-150mL) x 15br/min

= 5,250mL/min

Overall:

Alveolar ventilation = total ventilation - dead space ventilation

Question 14

Tidal volume is mixture of gases of what ‘areas’

Answer 14

Gas from anatomic dead space

And

Alveolar gas…

Question 15

CO2 levels in alveolar gas and blood are…

Answer 15

Same

Because CO2 has a higher diffusion constant than O2

Question 16

Measuring [CO2] in expired gas

Answer 16

Alveolar vent. = (CO2 vent/CO2 press) x constant

CO2 ventilation = alv vent x fractional conc of CO2

Question 17

If alveolar ventilation is halved…and CO2 production stays the same

Answer 17

Then…

Alveolar and arterial pCO2 will double

Inverse relationship

Question 18

As alveolar ventilation increases….

Answer 18

The alveolar P-CO2 decreases

Bringing alveolar P-O2 closer to inspired P-O2

Question 19

What does Fowler’s method measure

Answer 19

Anatomic dead space

Question 20

What does Bohr method measure

Answer 20

Physiologic dead space

This is increased with pathology

Question 21

Regional differences in ventilation

Answer 21

Upper < middle < lower lung

Due to gravity