Asthma

Question 1

What is asthma?

Answer 1

Chronic inflammatory disease of the airways

- Involves airway inflammation, structural remodelling and contraction of bronchial smooth muscle

Question 2

What are the key features of asthma?

Answer 2

• Wheeze, SoB, chest tightness and cough that varies over time and in intensity
• Variable expiratory airflow limitation

Question 3

What makes asthma different from COPD?

Answer 3

The variability of the expiratory airflow

Question 4

What are structural features of asthmatic airways?

Answer 4

• Bronchial hyper responsiveness
• Mucous cell metaplasia → plugs the airways
• Thickening of the bronchial wall
• Bronchoconstriction
• inflammation

Question 5

What are the 5 asthma phenotypes?

Answer 5

1) Allergic asthma
2) Non-allergic asthma
3) Late-onset asthma
4) Asthma with fixed airflow limitation
5) Asthma with obesity

Question 6

Describe the features of allergic asthma

Answer 6

• Most easily recognised
• Usually commences in childhood
• Associated with past/family history of allergic disease
• Usually presents with eosinophilic airway inflammation
• Good response to ICS

Question 7

Describe the features of non-allergic asthma

Answer 7

• Sputum may be neutrophilic, eosinophilic or with few inflammatory cells
• Less response to ICS bc tend to work on Th2 cells so if this is not present, doesn’t really work

Question 8

Describe the features of late onset asthma

Answer 8

• More common in women

- Tendency to non allergic phenotype so higher doses of ICS required

Question 9

Describe the features of asthma with fixed airflow limitation

Answer 9

• Long standing asthma

- Airflow limitation thought to be due to airway wall remodelling rather than inflammation

Question 10

Describe the features of asthma with obesity

Answer 10

• Prominent respiratory symptoms

- Little eosinophilia

Question 11

What are the main characteristic features of asthma?

Answer 11

1) Variable airways narrowing → airflow obstruction that is reversible (spontaneously or with treatment)
2) Non-specific airways hyper responsiveness to innocuous stimuli e.g. cold air, irritants, pollutants → bronchoconstriction (airway resistance)
3) Mucosal inflammation
4) Airways remodelling

Question 12

What decreases after someone with asthma is exposed to a stimulus, and then increases as time goes on?

Answer 12

FEV1

Question 13

Describe the inflammatory features of an asthmatic airway

Answer 13

1) Inflammatory infiltrate → inflammatory cell recruitment i.e. Th2 cells, mast cells and eosinophils
2) Mucosal oedema → bronchial microvascular leak
3) Mucus hypersecretion → blockage of airways by mucus plugs
4) Bronchial smooth muscle contraction → action of inflammatory mediators

Question 14

Describe the remodelling features of an asthmatic airway (persistent alterations in airway structure)

Answer 14

1) Epithelial cell damage → leaky epithelium
2) Reticular BM thickening
3) Airway smooth muscle thickening
4) Submucosal mucus gland hypertrophy

Question 15

What two important roles does the epithelium play in asthma?

Answer 15

Barrier and immunity

Question 16

What type of hypersensitivity is involved in the early response to asthma?

Answer 16

Type I

Question 17

What type of hypersensitivity is involved in the late response to asthma?

Answer 17

Type IV

Question 18

What are the two types of asthma-associated risk factors?

Answer 18

1) Host factors (predisposition)

2) Environmental factors (precipitate asthma exacerbations)

Question 19

What are host asthma risk factors?

Answer 19

1) Genetic

2) Atopy → positive skin prick tests - type I

Question 20

What are environmental asthma risk factors?

Answer 20

1) Allergens
2) Occupational sensitisers e.g. vehicle spray painting, baking → occupational asthma
3) Air pollutants
4) Respiratory viruses (common cold)
5) Exercise
6) Drugs e.g. aspirin, NSAIDs
7) Tobacco smoke

Question 21

What does asthma (airway inflammation, structural remodelling, contraction of bronchial smooth muscle) lead to?

Answer 21

Airways hyper responsiveness and airflow obstruction

Question 22

What happens during an asthma attack?

Answer 22

Air gets in but the same amount of air can’t get out

Question 23

What is the most common cause for asthma exacerbations?

Answer 23

Virus → most common = rhinovirus (common cold)

Question 24

What is a flare up or exacerbation?

Answer 24

An acute or sub-acute worsening of symptoms and lung function compared with the patient’s usual status

Question 25

What are the steps of management of worsening asthma?

Answer 25

1) Self-management with a written asthma action plan 2) Management in primary care 3) Management in the emergency department and hospital

Question 26

What patients are at an increased risk of asthma-related death?

Answer 26

1) Any history of near-fatal asthma requiring intubation and ventilation 2) Hospitalisation or emergency care for asthma in last 12 months 3) Not currently using ICS, or poor adherence with ICS 4) Currently using or recently stopped using OCS → indicating severity of recent events 5) Overuse of SABAs, especially if more than 1 canister/month 6) Lack of written asthma action plan 7) History of psychiatric disease or psychosocial problems 8) Confirmed food allergy in patient with asthma

Question 27

What do you do for patients who are at an increased risk of asthma-related death?

Answer 27

Flag them for more frequent review

Question 28

Until when do you follow up all patients regularly after an exacerbation?

Answer 28

Until symptoms and lung function returns to normal

Question 29

Why do you follow up all patients regularly after an exacerbation?

Answer 29

- Patients are at an increased risk during recovery from an exacerbation - Exacerbations often represent failures in chronic asthma care, and they provide opportunities to review the patient's asthma care and management

Question 30

What do you check at a follow up visit from someone who had an asthma exacerbation?

Answer 30

1) The patient's understanding of the cause of the flare up 2) Modifiable risk factors e.g. smoking 3) Adherence with medications, and understanding of their purpose 4) Reliever should be used as-needed rather than routinely 5) inhaler technique skills 6) Written asthma action plan

Question 31

In what patients do acute asthma exacerbations frequently occur?

Answer 31

In patients who are not well controlled day-to-day → often due to avoidable factors e.g. poor adherence to ICS, smoking

Question 32

What does acute asthma treatment consist of?

Answer 32

1) Repeated high dose inhaled (or nebulised) salbutamol ± ipratropium 2) Systemic steroids (oral prednisolone or IV hydrocortisone) 3) Oxygen if reduced O2 saturations 4) IV magnesium as a single dose

Question 33

What are features of moderate acute asthma?

Answer 33

1) Increasing symptoms 2) PEF > 50-75% best or predicted 3) No features of acute severe asthma - SATS don't fall

Question 34

What are features of acute severe asthma?

Answer 34

Any of one of: 1) PEF 33-50% best or predicted 2) RR > 25 3) HR > 110 4) Inability to complete sentences in one breath

Question 35

What are features of life-threatening asthma?

Answer 35

1) PEF < 33% best or predicted 2) SpO2 < 92 3) PaO2 < 8 kPa 4) Normal PaCO2 (4.6-6) 5) Silent chest 6) Cyanosis 7) Poor respiratory effort 8) Arrhythmia (cause of death) 9) Exhaustion 10) Altered consciousness level 11) Hypotension

Question 36

What is near-fatal asthma?

Answer 36

Defined as raised PaCO2 and/or required mechanical ventilation with raised inflation pressures