Respiratory statics

Question 1

What is lung compliance?

Answer 1

The change in lung volume per unit change in transpulmonary pressure.

Question 2

What is chest wall compliance?

Answer 2

The change in chest wall volume per unit change in transthoracic pressure.

Question 3

Alveolar pressure minus intrathoracic pressure is called ____________________.

Answer 3

Transpulmonary pressure

Question 4

Intrathoracic pressure minus atmospheric pressure is ___________.

Answer 4

transthoracic pressure

Question 5

Another name for intrathoracic pressure is __________________________.

Answer 5

Intrapleural pressure or pleural pressure

Question 6

Lung elastance is the inverse of ____________.

Answer 6

Lung compliance.

Question 7

The elastic recoil of the lung is due to (1)_______, (2)________, and (3)_________.

Answer 7

Tissue elastic recoil, the elastic nature of inter connective lung structures, and surface tension.

Question 8

How does the presence of pulmonary surfactant affect lung compliance (Clung)?

Answer 8

It increases Clung.

Question 9

What would you expect to happen to lung compliance in a patient with emphysema, which reduces the amount of tissue interconnections in lung tissue?

Answer 9

It would be increased.

Question 10

What would you expect to happen to lung compliance in a patient with deficient pulmonary surfactant production?

Answer 10

It would be decreased.

Question 11

Lung compliance is ___________ at lower than at higher volumes.

Answer 11

Greater/larger

Question 12

Chestwall compliance is ___________ at lower than at higher volumes.

Answer 12

Smaller/lower

Question 13

A lung freshly excised from an animal is inflated to a volume of 200 ml and the pressure in the trachea is measured steady at 10 cm H₂O. The lung volume is then changed to be 100 ml where the steady pressure is now 4 cm H₂O. The lung compliance is _________.

1. 16.7 ml/cm H₂O
2. 25 ml/cm H2​O
3. 50 ml/cm H2​O
4. 0.06 cm H2​O/ml
5. -25 ml/cm H2​O

Answer 13

Option 1 is correct. Remember the definition of compliance on pg. 11 of the iBook.

Question 14

At FRC with relaxed respiratory muscles, the transthoracic pressure is –6 cm H2O. The transpulmonary pressure here is __________________.

Answer 14

+ 6 cm H₂O.

Question 15

At FRC + 0.5 liters with relaxed respiratory muscles and an occluded airway, the transpulmonary pressure is measured to be +8 cm H₂O. With the airway still occluded, the subject activates inspiratory muscles to lower the airway pressure to –8 cm H₂O. What is the transpulmonary pressure now?

Answer 15

+8 cm H₂O. (Ref. pg. 12 in iBook.)

Question 16

A subject inspires to the volume where the chestwall recoil would be 0 cm H₂O with relaxed muscles. Transpulmonary pressure is +10 cm H₂O at this volume. The subject relaxes all respiratory muscles at this volume with an occluded airway. What is the pleural pressure?

Answer 16

0 cm H₂O. (Ref. CW compliance curve on pg. 14 of iBook.)

Question 17

As in the previous question, a subject inspires to the volume where the chestwall recoil would be 0 cm H₂O with relaxed muscles. Transpulmonary pressure is +10 cm H₂O at this volume. The subject relaxes at this volume with an occluded airway. What is the alveolar pressure?

Answer 17

+ 10 cm H₂O. (The figure on pg. 16 of the iBook may help.)