asthma
Asthma
Definition
- presence ≥1 of: wheeze, breathlessness, chest tightness, cough plus variable airflow obstruction.
- airway hyper-responsiveness and inflammation
- should not be diagnosed on symptoms alone
Cause
Factors not causes- Family Hx: 3-6x more likely if family member has asthma
- Allergies
- viral
- Occupational exposure, pollution, smoking and obesity
Symptoms
- wheezing, breathlessness
- cough
- chest tightness
Signs
- audible wheezing, tachypnoea, cyanosis
- reduced PEFR, pulsus paradoxus (exaggerated drop in sBP>10 during inspiration)
- tachycardia, hypertension and then hypotension in extremis
- chest may be silent when air entry is poor
- subcutaneous emphysema may be present in severe cases
Diagnostics
- Fractional exhaled Nitric Oxide (FeNO)
- Spirometry looking at FEV1/FVC
- bronchial challenge and reversibility tests
during exacerbations:
- basic bloods: FBC, U&E, CRP, IgE (after definitive Dx)
- CXR for infective causes not for pneumothorax (this is clinical and should be treated as emergency if considered!)
Management
- short-acting β agonist (SABA)
- Inhaled corticosteroid (ICS) if symptoms ≥3/week or nocturnal or uncontrolled with SABA alone
- leukotriene receptor antagonist (LTRA) with ICS and review
- add long acting β agonist (LABA, eg salmeterol) + ICS and review
- if uncontrolled on ICS and LABA (+/- LTRA) consider change to combined ICS/LABA inhaler
- increasing ICS and long-acting muscarinic receptor antagonist or theophylline are next options
- prednisolone 40-50mg until recovery (minimum 5/7)
Author: Dr Dylan Jenkins Nov '23 refs