Mechanism of Breathing/Compliance

Question 1

Which muscles could be used during inspiration?

Answer 1

Diaphragm

External Intercostals

Question 2

Which muscles are used during quiet expiration?

Answer 2

NONE!

Active expiration: muscles in abdominal wall, scalenes, etc.

Question 3

Categorize each of the following as either obstructive/ restrictive:

1. Asthma
2. Bronchitis
3. Pulmonary fibrosis
4. Emphysema

Answer 3

1. obstructive
2. obstructive
3. restrictive
4. obstructive

Question 4

T/ F: patients with obstructive lung diseases breath at higher lung volumes

Answer 4

True

Question 5

List the four steps of inspiration

Answer 5

1. Contraction of inspiratory muscles
2. Inflation of chest cavity
3. Inflation of lung
4. Inward airflow

Question 6

Point to where a healthy person and a person with obstructive disease would be on this curve

Answer 6

Question 7

What is the intrapleural pressure in relation to the lung pressure?

Answer 7

Its more negative

• It creates a vacuum that helps pull out lungs with expanding chest cavity
• It not more negative = pneumothorax

Question 8

Why is the intrapleural pressure negative?

Answer 8

See image:

• Lung is trying to move in to its equilibrium position
• Chest wall is trying to move out to equilibrium position
• OPPOSING FORCES GENERATE A VACUUM

Question 9

What are the normal values of Pip (intrapleural pressure) at the end of inspiration? Expiration?

Answer 9

• 30 cm-H2O at end of inspiration
• 5 cm-H2O at end of expiration

Question 10

Draw the curves on this line of inspiration and then expiration

Answer 10

Question 11

What is the elastic recoil pressure?

Answer 11

The tendency for the lung to try to return to its intrinsic equilibrium position producing a pressure

Question 12

Define compliance

Answer 12

Measure of how easily an applied pressure induces a volume change

• Measure of rigidity

Question 13

How do you calculate transpulmonary pressure (PTP)?

Answer 13

PTP= P(lung)– P(IP)

• Difference between inside and outside of lung

Question 14

At what transpulmonary pressure is there the highest degree of compliance?

Answer 14

• 15 cm-H20
• Or the middle of the curve when the slope is highest

Question 15

What is hysteresis?

Answer 15

=How the compliance curve looks depends on whether you are in inspiration or expiration

• *Lower compliance when inspiring*

Question 16

Give an example for a disease that increases & decreases compliance

Answer 16

• Emphysema: increased compliance
• Pulmonary fibrosis: decreased compliance

Question 17

For the following two diseases, will inspiration or expiration be most affected?

1. Emphysema
2. Pulmonary fibrosis

Answer 17

Emphysema: problems with expiration

Pulmonary fibrosis: problems with inspiration

Question 18

Which disease is represented by the following curve?

Answer 18

Emphysema

Question 19

What can cause a reduction in chest wall compliance?

Answer 19

Causes of reduced chest wall compliance

• Old age
• Obesity
• Scar tissue

Question 20

What effect will decreased lung compliance on the Volume/ pressure curve?

Answer 20

1. Decreased volumes at a given pressure
2. Decreased tidal volume
3. same compliance