Asthma

Definition
• Characterized by : recurrent dyspnea, cough, wheeze
• Caused by : reversible airway narrowing
• Factors :
o Bronchial muscle contraction (triggered by stimuli)
o Mucosal swelling/inflammation (mast cells)
o Excess mucus production (inflammatory mediators)

Pathogenesis:?

Microbiology??

Symptoms
• Intermittent dyspnea
• Cough
• Wheeze
• Sputum

Signs
• Tachypnoea
• Audible wheeze
• Hyperventilation
• Diminished air entry
• Polyphonic wheeze
• RR >25/min
• Cyanosis
• Pulse >110bpm

Hx
• Precipitants
• Diurnal variation
• Exercise
• Disturbed sleep
• Acid reflux
• Other atopic disease
• Occupation
• Days off?

Test
1) Acute asthma
• PEF
• Sputum culture
• FBC
• U&E
• CRP
• Blood culture
• ABG analysis
• CXR (to exclude infection/pneumothorax)

2) Chronic asthma
• PEF
• Diurnal variation
• Spirometry
• Skin-prick test
• Serology (aspergillosis)

Tx:
1) Chronic asthma
• Behavior – smoking, avoidance of precipitants, education
• BTSG:
Step 1: Ocassional short-acting inhaled B2-agonist (eg. Salbutamol) – next step if used >1 daily.
Step 2: standard-dose inhaled steroid (eg. Beclometasone 200ug/12h)
Step 3: long-acting B2-agonist (eg. Salmeterol) – if inadequate, increase dose of beclometasone 400ug/12h. if no effect of long-acting  stop
Step 4: trials of beclometasone 1000ug/12h,
modified-release of theophylline,
modified-release B2-agonist / oral leukotrine receptors
Step 5: prednisolone


DDx:
• Pulmonary oedema
• COPD
• Large airway obstruction
• SVC obstruction
• Pneumothorax
• PE
• Bronchiectasis
• Obliterative bronchiolitis