Resp 3 - Ventilation

Question 1

What is TLC?

Answer 1

Total Lung Capacity (TLC) = EVERYTHING combined

When you inspire all the way in and fill your lungs up as much as possible, the volume of air in the lungs is the TLC

Question 2

What is VC?

Answer 2

Vital Capacity (VC) = how much air is within the confines of what we are able to inspire and expire  
i.e. TLC - RV

Question 3

What is FRC?

Answer 3

Functional Residual Capacity (FRC) = the volume of air in the lungs when the outwards recoil of the rib cage and the inward recoil of the lungs are in equilibrium
i.e. ERV + RV
It is the volume of air remaining in the lungs at the end of a tidal breath.

Question 4

What is IC?

Answer 4

Inspiratory Capacity = how much extra air you can take in on top of the FRC
i.e. TV + IRV

Question 5

What are the 4 main volumes?

Answer 5

TV
ERV
IRV
RV

Question 6

What are the 4 main capacities?

Answer 6

FRC
IC
VC
TLC

Question 7

What is IRV?

Answer 7

Inspiratory Reserve Volume
= amount of volume in reserve if you want to breathe more
Measure when taking big breath in - from the top of TV to the max.

Question 8

What is ERV?

Answer 8

Expiratory Reserve Volume

When taking a max expiration from minimum TV to the peak of expiration

Question 9

What is RV?

Answer 9

Residual Volume
Default amount of air that is in the lungs - cannot get rid of it
Not routinely measured/clinically important

Question 10

What is TV?

Answer 10

Tidal Volume
Usually nasal
oscillates between 300-500 mL of air
= air going in and out to meet metabolic need of the body.
usually measured at rest. Exercise increases TV.

Question 11

What are the two components of the chest-wall?

Answer 11

Independent Lung

Independent rib cage and muscles

Question 12

Describe how the pleural cavity allows the chest wall and the lungs to move in unison.

Answer 12

The pleural cavity has a fixed volume and is at negative pressure. This means that when the chest wall expands, the lung gets pulled with it. (they are not physically attached)

Question 13

What factors affect lung volumes and capacities?

Answer 13

Body size, sex, fitness (innate), disease, age

Question 14

What unit is commonly used when describing lung pressures?

Answer 14

Unin: cm H20

Question 15

What are the three main lung pressures involved in respiratory mechanics? Define them.

Answer 15

Transmural Pressure = pressure across a tissue or several tissues
Transpulmonary Pressure = difference between alveolar and intrapleural pressure
Transrespiratory Pressure = tells us the direction of airflow in the airways - most important. If positive –> expiration

Question 16

Give two examples of positive pressure breathing.

Answer 16

CPR and Ventilators

Normal breathing = negative pressure breathing

Question 17

What sign is the pressure during expiration? Inspiration?

Answer 17

Expiration –> Positive
Inspiration negative as chest wall expands. When air comes in, pressure comes back to 0 - start of expiration
This leads to a graph

Question 18

What is the difference in alveolar pressure between the end of a tidal expiration and the end of tidal inspiration? Explain your answer.

Answer 18

NO DIFFERENCE - during inspiration, the thoracic cavity expands and so the alveoli expand and the pressure decreases. Air is drawn in to the alveoli and the pressure becomes the same as it was at the end of expiration.

Question 19

Define Dead Space.

Answer 19

Parts of the airways and lungs that do not participate in gas exchange.

Question 20

What are the two different types of dead space?

Answer 20

Anatomical Dead Space and Alveolar Dead Space

Question 21

What is the normal physiological dead space of a healthy individual?

Answer 21

150 mL - physiological dead space is usually equivalent to anatomical dead space because normal healthy people don’t have alveolar dead space

Question 22

State two reversible procedures that can change dead space.

Answer 22

Tracheostomy

Ventilators

Question 23

Explain the chest wall relationship diagram (volume against pressure).

Answer 23

Expanding the chest wall to 6 L takes relatively little pressure because its natural tendency is to expand. Expanding the lungs to 6 L takes a lot more effort and pressure because its natural tendency is to recoil inwards. So the curves are different.
Curve of lung + curve of chest wall has sigmoid shape.
This indicates that around FRC (at the middle, when curve crosse y axis = FRC) it is easy to ventilate whereas emptying totally is hard.

Question 24

What assessments are used to measure lung capacity?

Answer 24

Volume-time curve
Peak expiratory flow
Flow-volume loop

Question 25

Define FVC, FEV1 and FET.

Answer 25

FVC - maximum expiratory volume
FEV1 - how much air volume comes out in 1 second
FET - time taken to reach max exp volume

Question 26

How would these values change for a) someone with obstructive lung disease, b) someone with restrictive lung disease?

Answer 26

a) FVC - decreases a lot
FEV1 decreases a lot - not very fast and long
FET increases
b) FVC decreases
FEV1 decreases but not too much - still fast just not very long
FET decreases

Question 27

State normal FEV1/FVC values for a normal person, someone with obstructive lung disease and someone with restrictive lung disease.

Answer 27

Normal - 73%
Obstructive - 53%
Restrictive - 97%

Question 28

Describe the general arrangement of a flow-volume loop.

Answer 28

Looks like a tear drop

Question 29

Describe how the flow-volume loop changes for a) mild obstructive disease, b) severe obstructive disease and c) restrictive disease.

Answer 29

a) Displaced to the left and indented exhalation curve
b) Shorter curve, displaced to the left, indented exhalation curve (same as mild but worse)
c) Displaced to the right, narrower curve (smaller - restricted)

Question 30

Describe how the flow-volume loop will change for a) variable extrathoracic obstruction, b) variable intrathoracic obstruction and c) fixed airway obstruction.

Answer 30

a) Blunted inspiratory curve, otherwise normal (so bottom is higher)
b) Blunted expiratory curve, otherwise normal (so top peak not present - flat)
c) Blunted inspiratory and expiratory curve, otherwise normal - so looks like a square circle