Pathology: Chronic,reversible airway inflammation causing obstruction to airflow due to increasedsensitivity to a variety of stimuli
2phases:
· Early reaction (minutes):bronchospasm
· Late reaction (3-5 hours): oedemaand mucus
Aetiology: Genetic: Polygenic inheritance, atopy
Environmental: house dust mites, pet-derived allergens,smoke, pollen and work
place agents, NSAIDs, beta-blockers,cold weather
Symptoms: Wheeze,shortness of breath, cough, chest tightness.
Signs: Polyphonicwheeze on auscultation, tachypnoea, diurnal variation
Investigations: Spirometry: >15% improvement after B2agonist/steroid trial
Peak Expiratory Flow (PEF): >20% diurnal variation for>3days
Chest X-Ray: To exclude other diagnoses e.g.pneumothorax, infection
ABG: To assess for hypoxia or acid base disturbance
Treatment: Assessment of severity: To classifyModerate, Acute Severe or Life-threatening
Supplementary oxygen: Aim to keep saturations between 94-98%
B2 agonist bronchodilators: inhaled or nebulised
Ipratropium bromide: Acute severe, life threatening orpoor B2 agonist response
Steroids: Given in all cases of acute asthma
Magnesium sulphate: consider a single dose in near fatal orlife-threatening asthma
ITU: if life threatening or near-fatal asthma failingto respond to initial therapy
Complications: Pneumothorax,bronchiectasis
Prognosis: Mortalityfrom acute attacks is ~1200 per year
