Ventilation

Question 1

Minute ventilation units

Answer 1

TV X RR

(Volume/ breath) x (frequency of breaths/minute)

Normal tidal volume= 500 ml/breath

Normal frequency= 15 breaths / min

Minute ventilation= 500 x 15= 7,500 ml/min

Question 2

Where does the tidal volume go?

Answer 2

Normal tidal volume = 500 ml

150 ml -> anatomic dead space

The rest goes into alveolar gas

Question 3

What is anatomic dead space roughly equivalent to?

Answer 3

Ideal body weight

Question 4

Dead space ventilation

Answer 4

Breaths/min X volume of dead space

Question 5

What is total ventilation - dead space ventilation?

Answer 5

Alveolar ventilation

Question 6

Normal values: FRC

Composed of what two values

Answer 6

Functional residual capacity
3 L

Expiratory reserve volume 1.5 L

Residual volume 1.5 L

Question 7

Normal values: IC

Composed of what two values

Answer 7

Inspiratory capacity
3 L

IRV 2.5 L

TV 0.5 L

Question 8

Normal values: Vital capacity

Answer 8

4.5 L

Question 9

Normal Values: Total Lung Capacity

Answer 9

6 L

Question 10

Which values cannot be measured?

Answer 10

RV

FRC= ERV + RV

TCL= VC + RV
(TLC= IC + FRC)

Question 11

Volume of air during normal quiet breathing

Answer 11

TV

Question 12

Air that can be inhaled after a normal inhalation

Answer 12

IRV

Question 13

Air that can be exhaled after a normal exhalation

Answer 13

ERV

Question 14

Air that remains in the lung after a maximal expiration

Answer 14

RV

Question 15

Air that can be inhaled after a normal exhalation

Answer 15

IC

Question 16

Air that remains after a normal exhalation

Answer 16

FRC

ERV + RV

Question 17

Maximum air that can be inhaled

Answer 17

VC

Question 18

Air in the lungs after a maximal inhalation

Answer 18

TLC

Question 19

How does the helium dilution technique work?

Answer 19

C1 V1 = C2 (V1 + V2)
Have a known concentration and volume of helium in a container
Hook a patient up to the container, ask the patient to breath in and out
After a while, concentration of helium in container will decrease and level off
(this is at FRC)
Measure the new concentration of helium in container and solve for volume V2 (lung FRC)

With this you can measure RV (FRC - ERV)
To calculate TLC
(RV + IC)

Question 20

How does the body-box plethysmography work?

Answer 20

Boyle’s lay

P1V1 = P2V2

Question 21

What is the effect of increased depth of breathing vs increased rate of breathing on alveolar ventilation?

Answer 21

Tidal volume X RR = minute ventilation

Dead space ventilation = 150 ml X RR

Alveolar ventilation is minute ventilation - dead space ventilation

Therefore, increasing RR will cause more volume to go to the dead space vs alveolar space.

Increasing depth of breathing and decreasing RR will maximize alveolar ventilation bc less will go to the dead space.

Question 22

What is alveolar dead space?

Answer 22

Not anatomic, only happens in disease conditions.

Ventilated bu underperfused alveoli (no gas exchange)

Negligible in healthy people

Question 23

What conditions are associated with alveolar dead space

Answer 23

Low CO

Pulm embolism

(Little or no blood flow causes the vessel to shrivel up)

Question 24

Partial pressure of arterial CO2 is proportional to:

What can you exchange elimination of CO2 with?

Answer 24

CO2 production/ CO2 elimination

Alveolar ventilation bc Alveolar CO2 ~ arterial CO2

Question 25

Alveolar ventilation equation

Answer 25

Minute vent - dead space vent

(RR X Vt) - (RR X Vd)

RR X Vt (1 - Vd/Vt)

Question 26

Increased dead space will result in

Answer 26

Decreased alveolar ventilation

Question 27

Restriction can be diagnosed by

Answer 27

Reduced TLC