S8) Asthma

Question 1

What is asthma?

Answer 1

Asthma is a chronic inflammatory disorder of the airways, wherein widespread but variable airflow obstruction and increased airway responsiveness to a variety of stimuli occurs

Question 2

Identify 5 defining characteristics of asthma

Answer 2

• Chronic inflammatory process
• Susceptibility
• Variable airflow obstruction
• Airway hyper-responsiveness
• Reversibility

Question 3

Airways obstruction is a feature of both Asthma and Chronic Obstructive Pulmonary Disease (COPD).

How can one distinguish between the two conditions?

Answer 3

• Asthma: airway obstruction is often reversible (> 15% improve spontaneously, with bronchodilators/steroids)
• COPD: airway obstruction is not fully reversible (< 15% improve with treatment)

Question 4

Identify the most influential cells in asthma

Answer 4

Asthma is a chronic inflammatory process driven by TH2 cells

Question 5

What do TH2 cells do?

Answer 5

• Release cytokines, which attract and activate inflammatory cells (incl. mast cells and eosinophils)
• Activate B cells, which produce IgE

Question 6

In a sensitised atopic asthmatic, exposure to antigen results in a 2 phase response.

Briefly, identify and describe these 2 phases

Answer 6

• Immediate response (< 20 mins)
• Late phase response (3 – 12 hours later)

Question 7

What type of immune response is the immediate response to asthma?

Answer 7

The immediate response is an example of type 1 hypersensitivity

Question 8

In 5 steps, describe the immediate response to asthma

Answer 8

⇒ Allergen interacts with specific IgE antibodies

⇒ Mast cell degranulation occurs

⇒ Mediators are released (histamine, prostaglandin D2, leukotriene)

⇒ Bronchial smooth muscle contracts

⇒ Bronchoconstriction occurs

Question 9

What type of immune response is the late phase response to asthma?

Answer 9

The late phase response is an example of type IV hypersensitivity

Question 10

The late phase response to asthma involves inflammatory cells.

What do they do?

Answer 10

Inflammatory cells release mediators and cytokines which cause airway inflammation

Question 11

Identify 4 inflammatory cells involved in the late phase response to asthma

Answer 11

• Eosinophils
• Mast cells
• Lymphocytes
• Neutrophils

Question 12

What do eosinophils do in the late phase response to asthma?

Answer 12

Eosinophils release Leukotriene C4 and other mediators, some of which are toxic to epithelial cells, and causes shedding of epithelial cells

Question 13

Identify 5 events which causes the airway narrowing observed in asthma as a result of inflammation

Answer 13

• Mucosal oedema due to vascular leak
• Bronchial wall thickening due to inflammatory cell infiltration
• Mucous over-production
• Smooth muscle contraction
• Epithelium shedding

Question 14

Identify 6 major precipitating factors for asthma

Answer 14

• Allergens e.g. pollen, animals hair/dander
• Cold air (airway hyper-responsiveness)
• Exercise
• Irritants e.g. car exhaust fumes, smoke, strong smells
• Emotional distress
• Viral infections

Question 15

Identify 6 signs and symptoms of asthma

Answer 15

• Expiratory wheeze
• Cough
• Diurnal variability (worse at night & morning)
• Breathlessness
• Chest tightness
• Exercise induced wheeze

Question 16

What 3 questions can one ask a patient to ascertain asthma?

Answer 16

• Have you had difficulty sleeping because of your asthma symptoms?
• Have you had your usual asthma symptoms during the day?
• Has your asthma interfered with usual activities?

Question 17

What is the most common test used to confirm a diagnosis of asthma?

Answer 17

Spirometry

Question 18

What do the spirometry tracings in an asthmatic patient usually show?

Answer 18

Obstructive condition – FEV₁/FVC is reduced

Question 19

Which further test can be used to confirm an asthma diagnosis if the spirometry tracing is normal?

Answer 19

Methacholine / histamine challenge to determine airway hyper-responsiveness

Question 20

Identify 3 investigations used to measure the airway inflammation in asthma

Answer 20

• Peripheral blood eosinophil count (FBC)
• Induced sputum (eosinophils, neutrophils)
• FeNO (exhaled nitric oxide)

Question 21

Identify 5 aims of asthma management

Answer 21

• No daytime symptoms
• No night-time awakening due to asthma
• No asthma attacks
• No limitations on activity
• Normal lung function

Question 22

Identify and describe 3 factors which affect asthma treatment

Answer 22

• Pharmacological management: incorrect or suboptimal prescribing
• Clinical factors: environmental (triggers), medication, co-existing condition
• Behavioural factors: sub-optimal adherence, poor inhaler technique, smoking

Question 23

Outline the principles of asthma treatment

Answer 23

• Smoking cessation
• Inhaler technique
• Monitoring
• Pharmacotherapy
• Lifestyle
• Education

Question 24

Identify the 5 stages in asthma treatment

Answer 24

1. Regular preventer
2. Initial add-on therapy
3. Additional add-on therapies
4. High dose therapies
5. Continuous/frequent use of oral steroids

Question 25

What is the regular preventer in asthma treatment? (first line)

Answer 25

Low dose inhaled corticosteroid (ICS)

Question 26

What is the initial add on therapy in asthma treatment? (second line)

Answer 26

• Low dose inhaled corticosteroid (ICS)
• Inhaled long acting β₂ agonists (LABA)

Question 27

What are the additional add on therapies in asthma treatment? (third line)

Answer 27

If no response / inadequate control from LABA:

• Increase ICS dose + continue LABA
• Continue LABA + ICS and trial LTRA, LAMA or theophylline

Question 28

What are the high dose therapies in asthma treatment? (fourth line)

Answer 28

• Increase to high-dose ICS
• Addition of 4th drug (LTRA, theophylline, LAMA, β₂-agonist tablet)

Question 29

Describe the continuous/frequent use of oral steroids in asthma treatment (last line)

Answer 29

• Low dose steroid tablet
• Maintain high dose ICS
• Refer to specialist care

Question 30

Describe the treatment of acute severe asthma

Answer 30

• Oxygen (high flow, 94-98%)
• Nebulised salbutamol
• Oral prednisolone

Question 31

Describe the treatment of life threatening asthma

Answer 31

• Nebulised ipratropium bromide (add to acute treatments)
• IV magnesium and/or IV aminophylline (add to acute treatments)
• Discuss with senior doctor and ICU