03 Ventilation

Question 1

What are the approximate values of tidal volume, inspiration reserve volume, expiratory reserve volume and residual volume

Answer 1

Tidal: 0.5L
IRV: 2.5L
ERV: 1.5L
RV: 1.5L

Question 2

What factors can affect lung volumes and capacities

Answer 2

Sex
Size/height
Age
Disease
Fitness

Question 3

Describe the terms transmural, transthoracic, transpulmonary and transrespiratory pressures

Answer 3

Transmural: pressure difference between inside and outside
Transrespiratory: pressure difference between alveolar sacs and atmosphere
Transthoracic: pressure difference between pleura and atmosphere
Transpulmonary: pressure difference between alveolar sac and pleura

Question 4

Compare anatomical and alveolar dead space

Answer 4

Anatomical dead space is in conducting zone: 16 generations without gas exchange has 150 ml

Alveolar dead space is in respiratory zone: 7 generations with gas exchange, typically has 0 ml

Question 5

Describe a situation when there is alveolar dead space

Answer 5

Non perfumed parenchyma (alveoli) with no gas exchange

Question 6

Describe the mechanics of ventilation

Answer 6

Pulling force - diaphragm

Outward and upward swinging force

Question 7

Describe the effect of obstructive disease and restrictive disease on FVC, FEV1, FEV1/FVC and RV

Answer 7

Obstructive: low/normal, low, low, high/normal
Restrictive: low, low, normal/high, low

Question 8

Compare obstructive and restrictive lung disease in terms of its mechanism, operating volume level, chronic/acute, pulmonary and extrapulmonary causes

Answer 8

Obstructive:

• the flow of air is disrupted
• the lungs are operating at high volume
• chronic causes: bronchitis and emphysema
• acute causes: asthma

Restrictive

• the inflation and deflation of the lungs are affected
• lungs are operating at lower volume
• pulmonary causes: fibrosis and interstitial lung disease
• extrapulmonary: obesity and neuromuscular disease

Question 9

Describe the effect of obstructive and restrictive diseases onflow-volume loop

Answer 9

Mild obstructive: leftward shift, indentation on exhalation (called coving)
Severe obstructive: as above + shorter curve (smaller peak)
Restrictive: rightward shift, shorter and narrower

Question 10

Describe the flow-volume loop of the obstruction conditions

Answer 10

Extrathoracic obstruction: denting of the inspiratory curve
Intrathoracic obstruction: denting of the expiratory curve
Fixed airway obstruction: denting of both curves