Lecture 5 - Mechanics of Ventilation

Question 1

Only condition of inspiration?

Answer 1

Alveolar pressure is lower than barometric pressure

Question 2

Intrapleural pressure is always?

Answer 2

subatmospheric

Question 3

Hookes Law in 1D and 3D?

Answer 3

1: Force proportional to change in length; 3D: change in volume proportional to change in pressure

Question 4

Components of lung compliance?

Answer 4

Tissue compliance, air-water surface tension, atelectasis

Question 5

Saline filled lungs vs air filled?

Answer 5

More compliant (less pressure) due to lack of air-water surface tension

Question 6

Laplace’s Law? (bubbles)

Answer 6

Pressure proportional to tension/radius

Question 7

Total Thoracic Compliance equation?

Answer 7

1/Ct = 1/C.lung + 1/C.CW

Question 8

Influence of Gravity on Compliance?

Answer 8

Lower point of lung has higher pressure (less negative), causing the same change of pleural pressure to cause greater change of vlume than at higher point with less pleural pressure - i.e. greater compliance

Question 9

Decreased pulmonary compliance - lung pathologies?

Answer 9

pulmonary fibrosis, alveolar oedema, elevated pulmonary venous blood pressure, atelectasis, surfactant deficiency

Question 10

Decreased pulmonary compliance - chest wall pathology?

Answer 10

increased stiffness of thorax