Resp - Chronic Asthma

Question 1

Definition of asthma

Answer 1

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

Question 2

Epidemiology

Answer 2

• Incidence: 5-8%, higher in children

- peaks at 5 years, most outgrow it by adolescence

Question 3

Pathophysiology: acute and chronic

Answer 3

• Acute (30mins): mast cell-Ag interaction leads to histamine release = bronchoconstriction, mucus plugs and mucosal swelling
• Chronic (>12h): TH2 cells release IL 3-5 —> mast cell, eosinophil and B cell recruitment = always remodelling

Question 4

Causes: 3 main categories with 2 examples each

Answer 4

• Atopy: T1 hypersensitivity to variety of antigens, dust mites, pollen, food, animals, fungus
• Stress: cold air, viral URTI, exercise, emotion
• Toxins: smoking, pollution, factory, NSAIDs, beta blockers

Question 5

Hx

Answer 5

• Ask about precipitants
• diurnal variation (worse at night)
• Exercise tolerance
• Other atopy: hay fever/eczema
• Home and job environment
• smoking Hx

Question 6

Symptoms

Answer 6

• cough +/- sputum (often at night)
• wheeze
• dyspnea
• diurnal variation

Question 7

Signs

Answer 7

• tachypnea, tachycardia
• widespread polyphonic wheeze
• hyper-inflated chest
• decreased air entry
• signs of steroid use

Question 8

Differential

Answer 8

• Younger pts: must consider severe dysfunctional breathing (ie hyperventilation)
• Pts >45ya: COPD or LV failure

Question 9

Distinguishing btw asthma, LVF and COPD (based on symptoms)

• Breathless on exertion
• Breathless at rest
• Wheeze
• Night time symptoms
• Identifiable triggers
• Progressive deterioration
• Smoker or previous smoker
• Previous cardiac event

Answer 9

• Breathless on exertion: A (+/-), LVF (+), COPD (+)
• Breathless at rest: A (+), LVF (-), COPD (-)
• Wheeze: A (+), LVF (+), COPD (-)
• Night time symptoms: A (+), LVF (+), COPD (-)
• Identifiable triggers: A (+), LVF (-), COPD (-)
• Progressive deterioration: A (-), LVF (+/-), COPD (++)
• Smoker or previous smoker: A (+/-), LVF (+), COPD (++)
• Previous cardiac event: (-), LVF (++), COPD (+/-)

Question 10

Ix:

Answer 10

• Bloods: FBC (eosinophilia), raised IgE, aspergillus serology
• CXR: hyperinflation
• Spirometry: obstructive pattern with FEV1: FVC <0.75 and with >15% improvement in FEV1 with B-agonist
• PEFR: monitoring/diary with diurnal variation of >20%
• Atopy: skin prick test

Question 11

Mx- general measures

Answer 11

TAME

• T: technique for inhaler use
• A: avoidance of allergens/smoke
• M: monitor: peak flow diary
• Educate: lease with specialise nurse, Rx compliance, emergency action plan

Question 12

Mx- drug ladder: Steps 1-2

Answer 12

1. SABA PRN: if use >1/d or nocturnal symptoms then step 2

2. Low dose inhaled steroid: beclometasone 100-400ug BD

Question 13

Mx- drug ladder: step 3

Answer 13

3. LABA: salmeterol 50ug bd
   - Good response: continue
   - Benefit but still poor control: increased inhaled steroid (beclometasone) to 400ug bd)
   - No benefit: discontinue LABA + increase steroid to 400ug

Question 14

Mx- drug ladder:steps 4-5

Answer 14

4. Trials of
   - Increased inhaled steroid to 1000ug BD
   - Leukotrienne receptor antagonist (Montelukast)
   - SR theophylline
5. Oral steroids
   - Eg oral prednisolone 5-10mg OD
   - Use lowest dose necessary for symptom control
   - maintain high-dose inhaled steroid too b/c they can reach areas very effectively
   - refer to asthma clinic

Question 15

How do NSAIDs exacerbate asthma?

Answer 15

• Block conversion of arichidonic acid to COX1 and this diverts production towards increased levels of Leukotriennes. (Via FLAP and 5-LO)
• Monteleukast is a Leukotrienne receptor antagonist

Question 16

Why should you ask patients about their mental health when assessing their asthma status?

Answer 16

• There is a very big association between poorly controlled asthma and depression.
• Antidepressants suppress cytokines production
• Hormone levels associated with stress can worsen asthma in patients.