Physiological Consequences of Disruption or Destruction of

Question 1

What is type 1 respiratory failure?

Answer 1

Respiratory failure due to gas exchange abnormality - leads to a fall in PaO2 - as gas exchange worsens ventilation increases which partially improves PaO2 but also leads to low PaCO2

Question 2

What is type 2 respiratory failure?

Answer 2

Respiratory failure due to inadequate ventilation - leads to low PaO2 (50mmHg)

Question 3

How does type 1 respiratory failure lead to type 2 respiratory failure?

Answer 3

If respiratory muscles become fatigued and so can no longer hyperventilate

Question 4

What is the surface area of the alveolar capillary membrane?

Answer 4

75 square metres

Question 5

What processes and diseases can effect the alveolar-capillary membrane?

Answer 5

inflammation, infection, fibrosis, emphysema, fluid, cancer

Question 6

What are the physiological effects of disruption the AC membrane?

Answer 6

Diffusion impairment for oxygen (not usually for CO2), difficult for lung mechanics and if enough of the lung is effected may lead to increased pulmonary artery pressure

Question 7

What are the causes for low PaO2?

Answer 7

Low PiO2, low ventilation, abnormal gas exchange (either low V/Q, shunt or diffusion impairment)

Question 8

How can you determine the cause for low PaO2?

Answer 8

The A-a gradient will be wider if there is abnormal gas exchange

Question 9

What are the mechanical effects on the lung of a restrictive lung disease?

Answer 9

breathlessness, increased elastic WOB, reduced lung volumes, altered pattern of breathing, reduced maximum ventilation

Question 10

What is the effect on compliance for restrictive lung diseases?

Answer 10

Reduced compliance

Question 11

What is the usual pattern of breathing in restrictive lung diseases?

Answer 11

small breaths and a fast rate

Question 12

What is the result of reduced compliance on lung volumes?

Answer 12

Will cause reduced lung volumes - TLC, RV, FRC, VC, FEV1, FVC

Question 13

What is the FEV1/FVC in restrictive lung disease?

Answer 13

Normal - because both FEV1 and FVC are reduced

Question 14

What influences compliance of the lungs?

Answer 14

tissue composition and surface tension in the alveoli

Question 15

What is compliance?

Answer 15

Change in volume/change in pressure

Question 16

What is the normal relationship between pressure and volume?

Answer 16

Initial expansion of the lung doesn’t require much pressure but as you get closer to the TLC you need to generate a lot of negative pressure

Question 17

What happens to lung compliance in pulmonary fibrosis?

Answer 17

Decreased lung compliance - need a lot of pressure to generate any change in volume

Question 18

What happens to lung compliance in emphysema?

Answer 18

Increased lung compliance - need very little change in pressure to generate change in volume

Question 19

What is the maximum ventilation in restrictive lung disease?

Answer 19

Reduced (35 x FEV1) because FEV1 is reduced

Question 20

Does the reduced maximum ventilation effect ability to exercise?

Answer 20

Yes, but exercise is usually more limited by hypoxia and or pulmonary hypertension which both worsen with exercise