Obstructive and Restrictive Lung Diseases

Question 1

How is forced expiratory volume (FEV1) measured?

Answer 1

Using a vitalograph

Question 2

Outline the pathophysiology of asthma

Answer 2

IMMEDIATE RESPONSE
1. Inhaled allergens bind to the IgE antibody present on mass cells
2. The mast cells release inflammatory mediators such as histamine
3. The inflammatory mediators cause the production of mucus, bronchoconstriction and oedema
DELAYED RESPONSE
1. Eosinophils are activated by the mast cells (chemotactic factors) and discharge proteins that damage the epithelium (eosinophil peroxidase)
2. This damage stimulates afferent nerves which activate parasympthathetic discharge
3. This increase in parasympathetic innervation causes an increase in mucus secretion and airway constriction

Question 3

What type of condition is asthma?

Answer 3

Type 1 hypersensitivity condition

Question 4

What allergens may trigger asthma?

Answer 4

Air pollutants, pollens, dust mites, moulds, animals, medications such as aspirin and NSAIDs and some foods

Question 5

What are the symptoms of asthma?

Answer 5

Coughing at night, during activity, wheezing or chest tightness on allergen exposure and prolonged duration of colds.

Question 6

What skin conditions may be associated with asthma?

Answer 6

Atopic dermatitis or eczema, believed to be due to type 1 hypersensitivity reactions also, but by unknown mechanisms

Question 7

What drugs are used to prevent asthma attacks?

Answer 7

Corticosteroids, long-acting beta-2-agonists and leukotriene modifiers to reduce inflammation, relax airway muscles and improve symptoms and lung function

Question 8

What drugs are usually given to relieve the immediate symptoms of an asthma attack?

Answer 8

Short-acting beta 2 agonists

Question 9

Why are spacers used in the administration of asthma medication?

Answer 9

These can greatly improve the penetration of inhaled drugs into the lungs and also reduce potential for adverse effects from medication

Question 10

Why are nebulisers used in the administration of asthma medication?

Answer 10

These are machines that produce an inhaled mist of mediated. They are used for small children or severe episodes of asthma attack.

Question 11

What is COPD?

Answer 11

A combination of chronic bronchitis and emphysema

Question 12

What is chronic bronchitis?

Answer 12

Chronic productive cough without clear cause; features include hypertrophy of bronchial glands, hyper secretion of mucus (forming plugs) and infection/inflammation

Question 13

What is emphysema?

Answer 13

This is where there is destruction of the alveolar walls (stroma) leading to reduced surface area and production of bullae

Question 14

What are bullae?

Answer 14

Accumulation of several alveoli clumped together due to wall destruction

Question 15

What is the main cause of emphysema and COPD?

Answer 15

Smoking

Question 16

What is the pathophysiology underlying (chronic bronchitis)

Answer 16

This condition is part of what makes up COPD; irritants damage the epithelium in the bronchioles and cause the proliferation of squamous cells and stimulation of mucus gland enlargement

Question 17

What is the pathophysiology of emphysema?

Answer 17

1. Cigarette smoke stimulates polymorphonuclear leucocytes (PMN) to release the enzyme serine elastase.
2. The smoke also inactivates the elastase inhibitor (1-antitrypsin)
3. The inactivation of 1-antitrypsin allows the serine elastase enzyme to destroy the elastic tissues of the lung
4. This produces stiffness and emphysema

Question 18

How can you differentiate between COPD and asthma?

Answer 18

Peak flow increases after salbutamol is given in asthmatics, but not in those with COPD

Question 19

What is the key feature of restrictive lung disorders?

Answer 19

Reduced vital capacity

Question 20

How do pneumonia, pneumothorax, atelactis and pulmonary fibrosis lead to reduced vital capacity?

Answer 20

These conditions cause a reduction in lung volume and therefore there is less room for air

Question 21

How does ankylosing spondylitis and kyphoscoliosis lead to reduced vital capacity?

Answer 21

They involve an external mechanical limitation lung volume

Question 22

What do flow-volume loops show?

Answer 22

Flow against lung volume (L/sec against L)

Question 23

Describe a normal flow-volume loop

Answer 23

The bottom represents inspriration

Question 24

Describe a normal flow-volume loop

Answer 24

The bottom represents inspiration and the top represents expiration:

> The bottom, inspiratory loop should be symmetrical and look like a semi-circle
The top, expiratory curve should rise steeply and fall slowly

Question 25

How can you determine PEV from a flow-volume loop?

Answer 25

On the superior expiratory curve, the highest point is the peak expiratory flow rate

Question 26

Generally, how does restrictive lung disease appear on flow-volume loops?

Answer 26

Tall and narrow flow-volume loops

Question 27

Generally, how does obstructive lung disease appear on flow-volume loops?

Answer 27

There is ‘scooping out’ of the expiratory portion of the loop, the inspiratory portion remains the same