Asthma

Question 1

Definition

Answer 1

• REVERSIBLE airway obstruction
• Due to bronchial hyper-reactivity
• Causing episodes of: dyspnoea, cough and wheeze.

Question 2

Pathophysiology of asthma

• Acute
• Chronic
• Stresses

Answer 2

ACUTE (30 mins)
- Mast-cell activation to Ag causing histamine release= bronchoconstriction, mucus plugs, mucosal swelling.

CHRONIC (12hrs)

• Th2 cells= IL-3 (mast cell) ,4 (eosinophil) ,5 (B cell).
• Type 1 hypersensitivity reaction.

Stresses

• Cold air
• Viral URTI
• Exercise
• Psychological/ emotional
• Allergens: house dust, mite, pollen

Question 3

Symptoms of chronic asthma

Answer 3

• Intermittent dyspnoea: includes poor exercise tolerance
• Wheeze
• Cough: especially at night/ disturbing sleep
• Acid reflux

Question 4

Signs of chronic asthma

Answer 4

• Diurnal variation
• Hx of allergies/ atopy/ family history
• Sh of pets, certain occupations

Examination

• Tachypnoea
• Tachycardia
• Widespread polyphonic wheeze
• Hyperinflated chest
• Reduced air entry

In acute attack

• Hyperventilation (RR>25)
• HR>110
• Inability to complete sentences
• Severe: silent chest, cyanosis, exhaustion, bradycardia confusion

Question 5

Investigations for asthma

Answer 5

Bloods

• FBC= raised WCC, eosinophils
• Raised IgE
• Aspergillus serology

Spirometry

• FEV1 <80%
• FEV1:FVC <70%
• Bronchial challenge with histamine/ methacholine
• Bronchodilator reversibility

Peak flow monitoring
- Diurnal variation >20%, dip in morning

FeNO (fractional exhaled NO)

• Measures airway inflammation.
• 40 ppb+ = positive.

CXR
- Hyperinflated chest

Allergy testing
- Skin prick/ RAST

In acute attack

• Sputum culture, blood culture
• ABG

Question 6

Bronchial challenge with histamine/ methacholine

Answer 6

Challenge to test degree of bronchoconstriction caused y methacholine.

In patients with asthma, they will respond to lower dose of histamine/ metacholin (8 mg/ml or less)

Question 7

Bronchodilator reversibility

Answer 7

Method of testing for asthma/ obstructive disease.

FEV1 is measured before bronchodilator is given, then measured again.

FEV1 of 12% increase or more, together with an increase in volume of 200 ml or more, as a positive test.

Question 8

Immediate treatment for acute severe asthma

Answer 8

Nebulisaed Salbutamol with oxygen

Oral prednisolone or IV hydrocortisone

Question 9

Treatment for life threatening severe asthma

Answer 9

1. Nebulised salbutamol every 15 mins
2. Ipratropium nebulised
3. MgSo4 IB

Other additions if worsens (hypercapnia, hypoxia, acidosis/alkalosis/ silent, altered GCS)

• IV aminophylline
• IV salbutamol