3+ Asthma

Question 1

What is asthma?

Answer 1

Chronic inflammatory disorder characterised by hyper-responsive airways. Over-reaction to stimuli causes reversible bronchoconstriction

Question 2

What is the epidemiology of asthma?

Answer 2

M>F under 18, F>M over 18

Childhood onset= allergic
Adult onset= non-allergic

Question 3

What are some triggers for asthma?

Answer 3

Cold, stress, exercise, allergens (dust, pollen, fur), infection, smoking, NSAIDs, pollution

Question 4

What are the 4 subtypes of asthma?

Answer 4

1. Atopic asthma: type 1 IgE mediated hypersensitivity reaction
2. Drug-induced: e.g. aspirin
3. Occupation: fumes, organic, chemical dusts
4. Non-atopic: no evidence of allergen sensitisation but activates similar pathways to atopic

Question 5

What is the physiology of asthma?

Answer 5

• Bronchial hyper-responsiveness to trigger
• Bronchial inflammation –> inflammation of the terminal bronchioles + smooth muscle contraction + oedema –> collapse of the bronchi

3 things:
1. Bronchial smooth muscle contraction
2. Mucosal inflammation
3. Increased mucous production

Question 6

What are the pathological findings of asthma?

Answer 6

• Smooth muscle hypertrophy and hyperplasia
• Excessive mucous
• Inflammation

Question 7

What are the histology findings of asthma?

Answer 7

• Charcot-leiden crystals formed by eosinophils + Curschmann’s spirals from mucin and cell debris

Question 8

What is the history of a patient presenting with asthma?

Answer 8

• Recurrent episodes of dyspnoea, cough and wheeze
• Persistent dry cough that worsens at night, with exercise and with triggers
• Chronic allergic rhinitis with nasal congestion
• SEVERE: status asthmaticus = failure to subside for days to weeks, can cause respiratory failure

Question 9

What are the features of asthma on examination?

Answer 9

Tachypnoea
Audible wheeze
Hyper-inflated chest –> hyper-resonant to percussion
Auscultation: reduced air entry, widespread polyphonic wheeze (expiratory)

Question 10

What Ix do you do when you suspect asthma?

Answer 10

Bedside: Spirometry
- Obstructive lung disease

Labs for acute attack:
- FBC
- UEC
- CRP
- Blood cultures
- Sputum culture
- ABG
- PFTs: if FEV1/FVC is normal, do a metacholine challenge to induce bronchoconstriction (asthma is inducible and reversible for PFTs)

Imaging:
- CXR if indicated in severe patients or to rule out DDx

Question 11

What do you see with asthma on spirometry?

Answer 11

• Obstructive lung disease
• Decreased FEV1/FVC ratio
• Decreased FEV1
• Reversible with bronchodilators
• Inducible with metacholine challenge

Question 12

What is the treatment hierarchy for asthma?

Answer 12

1. ALL patients:
   - SABA as needed
2. MOST patients:
   - Regular low dose ICS preventer
   - SABA as needed
3. Some patients:
   - ICS/LABA combination
   - SABA as needed

Question 13

What is a a SABA + an example?

Answer 13

Short acting B2AR agonists

Salbutamol

Question 14

What is a LABA + an example?

Answer 14

Long acting B2AR agonists

Formoterol

If a patient is on a LABA they MUST also be on ICS

Question 15

What is an example of ICS and what are they used for?

Answer 15

Flixotide

Used for maintenance treatment of Th2 eosinophilic asthma –> reduce the expression of genes and proteins that drive inflammation

Question 16

What are some management options beyond SABA, LABA and ICS?

Answer 16

Leukotriene receptor antagonists:
- Montelukast but only reverse leukotriene induced constriction so used mostly as an add on the LABA and ICS

mABs against IgE

mABs against IL-5

Question 17

What is a complication of asthma?

Answer 17

Status asthmaticus: exacerbation of asthma that does not respond to bronchodilators
- Patients are in respiratory distress with signs of severe dyspnoea
- Treat with O2, ipatropium and corticosteroids
- Can give nebulised adrenalin if needed