Lung Funtction Tests And Common Lung Conditions

Question 1

What are obstructive lung diseases?

Answer 1

Obstruction of air flow, especially on expiration

Question 2

Examples of obstructive lung disorders?

Answer 2

• Asthma
• COPD (chronic obstructive pulmonary disease)
  • Chronic bronchitis – inflammation of the bronchi
  • Emphysema – destruction of the alveoli + loss of elasticity

Question 3

What are restrictive lung diseases?

Answer 3

Restriction of lung expansion, loss of lung compliance

Question 4

Examples of restrictive lung diseases

Answer 4

o Fibrosis
- Formation of excess fibrous connective tissue – “stiff” lung
- Idiopathic (unknown cause)
- Asbestosis (and other occupational origins)
o Infant respiratory distress syndrome (insufficient surfactant production)
- Less willing to expand
o Oedema
- Fluid around alveoli creates pressure which resists inflation of alveoli
o Pneumothorax
- Air in pleural cavity pushing apart the pleurital membrane from the visceral membrane
- Lung now independent from chest wall and diaphragm and will no longer expand

Question 5

What is spirometry?

Answer 5

Technique to measure lung function
Measurements are static or dynamic:
- Static – only consideration made is volume exhaled
- Dynamic – time taken to exhale a certain volume measured

(Can only measure volumes you expire e.g. NOT total lung capacity)

Question 6

What is FEV1/FVC ratio?

Answer 6

• Forced expiratory volume in 1 second (FEV1)
  o Fit, healthy, young adult males: 4.0L
• Forced vital capacity (FVC) – total amount of air you can expire
  o Fit, healthy young adult males: 5.0L
• FEV/FVC = 80%

Question 7

Spirometry in obstructive disease, what happens to FEV1/FVC?

Answer 7

• Big reduction in FEV1
  
  • Rate of air expired is much slower – increase in resistance in airways or loss of elastic recoil in alveoli
• Total expired volume (FVC) reduced as less air is able to get out

Therefore ratio reduced

Question 8

Spirometry in restrictive disease, what happens to FEV1/FVC?

Answer 8

• FEV1 decreases
  
  • Only because there is less air in the lungs anyway
• Rate of air flow is not impeded in restrictive lung diseases
• Total amount of air expired is restricted as less air in lungs in first place

Ratio is unchanged