Respiratory statics Flashcards
Appreciate the elastic forces required for breathing
What is lung compliance?
The change in lung volume per unit change in transpulmonary pressure.
What is chest wall compliance?
The change in chest wall volume per unit change in transthoracic pressure.
Alveolar pressure minus intrathoracic pressure is called ____________________.
Transpulmonary pressure
Intrathoracic pressure minus atmospheric pressure is ___________.
transthoracic pressure
Another name for intrathoracic pressure is __________________________.
Intrapleural pressure or pleural pressure
Lung elastance is the inverse of ____________.
Lung compliance.
The elastic recoil of the lung is due to (1)_______, (2)________, and (3)_________.
Tissue elastic recoil, the elastic nature of inter connective lung structures, and surface tension.
How does the presence of pulmonary surfactant affect lung compliance (Clung)?
It increases Clung.
What would you expect to happen to lung compliance in a patient with emphysema, which reduces the amount of tissue interconnections in lung tissue?
It would be increased.
What would you expect to happen to lung compliance in a patient with deficient pulmonary surfactant production?
It would be decreased.
Lung compliance is ___________ at lower than at higher volumes.
Greater/larger
Chestwall compliance is ___________ at lower than at higher volumes.
Smaller/lower
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 _________.
- 16.7 ml/cm H2O
- 25 ml/cm H2O
- 50 ml/cm H2O
- 0.06 cm H2O/ml
- -25 ml/cm H2O
Option 1 is correct. Remember the definition of compliance on pg. 11 of the iBook.
At FRC with relaxed respiratory muscles, the transthoracic pressure is –6 cm H2O. The transpulmonary pressure here is __________________.
+ 6 cm H2O.
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?
+8 cm H2O. (Ref. pg. 12 in iBook.)
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?
0 cm H2O. (Ref. CW compliance curve on pg. 14 of iBook.)
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?
+ 10 cm H2O. (The figure on pg. 16 of the iBook may help.)
