Chronic asthma

Question 1

definition of chronic asthma

Answer 1

Episodic, reversible airway obstruction due to bronchial hyper-reactivity to a variety of stimuli.

Question 2

epidemiology of chronic asthma

Answer 2

• Incidence 5-8% (↑ in children vs. adults)

- Peaks at 5yrs, most outgrow by adolescence

Question 3

pathophysiology of acute asthma

Answer 3

• Mast cell-Ag interaction → histamine release

- Bronchoconstriction, mucus plugs, mucosal swelling

Question 4

pathophysiology of chronic asthma

Answer 4

• TH2 cells release IL-3,4,5 → mast cell, eosinophil and B cell recruitment
• Airway remodelling

Question 5

general causes of asthma

Answer 5

• atopy
• stress
• toxins

Question 6

atopy causes of asthma

Answer 6

• T1 hypersensitivity to variety of antigens

- Dust mites, pollen, food, animals, fungus

Question 7

stress causes of asthma

Answer 7

• Cold air
• Viral URTI
• Exercise
• Emotion

Question 8

toxin causes of asthma

Answer 8

• Smoking, pollution, factory

- Drugs: NSAIDS, β-Blockers

Question 9

symptoms of chronic asthma

Answer 9

• Cough ± sputum (often at night)
• Wheeze
• Dyspnoea
• Diurnal variation with morning dipping

Question 10

things to consider when taking an asthma history

Answer 10

• Precipitants
• Diurnal variation
• Exercise tolerance
• Life effects: sleep, work
• Other atopy: hay fever, eczema
• Home and job environment

Question 11

signs of asthma

Answer 11

• Tachypnoea, tachycardia
• Widespread polyphonic wheeze
• Hyperinflated chest
• ↓ air entry
• Signs of steroid use

Question 12

diseases associated with asthma

Answer 12

• GORD
• Churg-Strauss
• Allergic Bronchopulmonary Aspergillosis (ABPA)

Question 13

differential diagnosis of asthma

Answer 13

• pulmonary oedema (cardiac asthma)

- COPD

Question 14

investigations for asthma

Answer 14

1. Bloods
   - FBC (eosinophila)
   - ↑IgE
   - Aspergillus serology
2. CXR: hyperinflation
3. Spirometry
   - Obstructive pattern c¯ FEV1:FVC < 0.75
   - ≥15% improvement in FEV1 c¯ β-agonist
4. PEFR monitoring / diary
   - Diurnal variation >20%
   - Morning dipping
5. Atopy: skin-prick, radioallergosorbent test (RAST)

Question 15

general management of asthma

Answer 15

TAME
- Technique for inhaler use
- Avoidance: allergens, smoke (ing), dust
- Monitor: Peak flow diary (2-4x/d)
- Educate
> Liaise c¯ specialist nurse
> Need for Rx compliance
> Emergency action plan

Question 16

drug ladder for chronic asthma (British Thoracic Society Guidelines)

Answer 16

1. Short-acting β agonist PRN + low-dose inhaled steroid (beclomethasone 100-400ug bd)
2. Long-acting β agonist (salmeterol 50ug bd)
3. ↑ inhaled steroid to up to 1000ug bd
4. Leukotriene receptor antagonist + Theophylline + Modified-release β agonist PO
5. oral steroids (e.g. prednisolone 5-10mg OD)

Question 17

guidance on use of Long-acting β agonists

Answer 17

• Good response: continue
• Benefit but control still poor: ↑ steroid to 400ug bd
• No benefit: discontinue + ↑ steroid to 400ug bd

If control is still poor consider trial of:
- Leukotriene receptor antagonist (e.g. monetelukast)
> Esp. if exercise- / NSAID-induced asthma
- Sustained-release Theophylline

Question 18

guidance on use of oral steroids

Answer 18

• Use lowest dose necessary for symptom control
• Maintain high-dose inhaled steroid
• Refer to asthma clinic