27. Work of Ventilation 1

Question 1

What is work of breathing?

Answer 1

Work required to move the lung and chest wall

Question 2

Higher tidal volume leads to an increase in what type of work?

Answer 2

Elastic

Question 3

Higher rate leads in an increase in what type of work?

Answer 3

Non-elastic

Question 4

What is elastic work?

Answer 4

Force to expand the lung against its elastic properties

Question 5

What is resistive/non-elastic work?

Answer 5

Force to overome air-flow resistance

Question 6

What is compliance?

Answer 6

Ease with which the lungs can be stretched or inflated

Compliance= Change in lung volume/ change in transmural pressure

Question 7

When is static compliance measured?

Answer 7

No airflow

Airway resistance does not contribute

Question 8

When is dynamic compliance measure?

Answer 8

During airflow

Question 9

What does specific compliance measure?

Answer 9

Elastic properties
Lung volume is taken into account
Compliance/FRC

Question 10

What happens to the hysteresis curve in obstructive diseases?

Answer 10

Area in loop widens

Increased work of breathing

Question 11

What happens to the hysteresis curve in restrictive diseases?

Answer 11

Curve is pulled to the right

More negative pressure is needed to overcome lung stiffness

Question 12

What causes increased compliance?

Answer 12

Loss of elastin fibres
Early emphysema
Ageing

Question 13

What causes decreased compliance?

Answer 13

Chest wall issues eg. scoliosis

Pulmonary fibrosis

Question 14

What is elastance?

Answer 14

Measure of recoil force

Question 15

What contributes to elastic work?

Answer 15

Tissue elasticity

Surface tension

Question 16

What is the function of surfactant?

Answer 16

Reduces surface tension
Stabilises alveoli of different sizes
Contributes to immunity in the lung

Question 17

What would happen to small alveoli without surfactant?

Answer 17

They would empty in bigger alveoli and collapse due to their higher pressure

Question 18

What is the treatment of newborn respiratory distress syndrome?

Answer 18

Corticosteroids to mother
Oxygen through continuous positive airway pressure
Survanta

Question 19

How does alveoli interdependence contribute to stabilisation?

Answer 19

When an alveolus in a group of alveoli begins to collapse, the surrounding alveoli are stretched
Neighbouring alveoli recoil in response, pulling the collapsing alveolus back open