Asthma – Overview 

Asthma is a chronic inflammatory disorder of the airways characterized by variable airflow obstruction, airway hyper responsiveness, and reversible symptoms such as wheezing, shortness of breath, chest tightness, and cough. It often involves a type 2 helper T-cell (Th2)-mediated immune response, leading to airway inflammation. 

Epidemiology 

Global prevalence: ~1–18% depending on region. 
Can occur at any age; commonly begins in childhood. 
More prevalent in atopic individuals and those with a family history of asthma or allergic diseases. 

Pathophysiology 

Airway Inflammation 
Mediated by eosinophils, mast cells, T-lymphocytes. 
Leads to mucosal oedema and increased mucus secretion. 

Airway Hyper responsiveness 
Exaggerated bronchoconstriction in response to triggers (allergens, irritants, exercise, cold air). 

Airflow Obstruction 
Due to smooth muscle contraction, mucus plugging, and airway wall oedema. 
Usually reversible spontaneously or with treatment. 

Chronic Changes (in persistent asthma) 
Airway remodelling: thickening of basement membrane, smooth muscle hypertrophy, goblet cell hyperplasia. 

Aetiology / Triggers 

Allergens: Dust mites, pollen, pet dander, mold. 
Environmental: Smoke, pollution, cold air. 
Exercise-induced asthma 
Infections: Respiratory viruses (e.g., rhinovirus) 
Medications: NSAIDs, beta-blockers. 
Stress and emotions may exacerbate symptoms. 

Clinical Features 

Symptoms are often episodic: 

Wheezing 
Dyspnoea 
Chest tightness 
Cough (often worse at night or early morning) 

Signs during attack: 
Tachypnoea, tachycardia 
Prolonged expiratory phase 
Use of accessory muscles 
Reduced peak expiratory flow rate (PEFR) 

Diagnosis 

1. Clinical Diagnosis: 
History of episodic symptoms. 
Symptom variability and triggers. 
Improvement with bronchodilator therapy. 

2. Investigations: 

Spirometry (gold standard): 
FEV1/FVC <0.7 
Reversibility: FEV1 improves ≥12% and ≥200 mL after inhaled bronchodilator. 

Peak Expiratory Flow (PEF): 
Diurnal variation >10–15%. 

Bronchial Provocation Test: Methacholine or histamine challenge if diagnosis unclear. 
Allergy testing: Skin prick or specific IgE. 
Other tests: Chest X-ray usually normal; may help rule out other conditions. 

Classification (GINA 2025) 

By severity (before treatment): 
Intermittent 
Mild persistent 
Moderate persistent 
Severe persistent 

By control (on treatment): 
Well-controlled 
Partly controlled 
Uncontrolled 
Number of ICU admissions

Management 

1. Acute Asthma Exacerbation 
Oxygen to maintain SpO2 ≥ 92%. 
Short-acting beta-agonists (SABA): e.g., salbutamol inhaler or nebulizer. 
Systemic corticosteroids: oral prednisone or IV methylprednisolone. 
Adjuncts: Ipratropium bromide, magnesium sulfate (severe cases). 

2. Long-term Control 
Stepwise therapy (GINA guidelines): 
Low-dose inhaled corticosteroids (ICS) 
ICS + long-acting beta-agonist (LABA) if uncontrolled 
Consider leukotriene receptor antagonists (LTRAs) or biologics for severe asthma 
Trigger avoidance and patient education 
Regular monitoring: Symptoms, PEFR, spirometry 

Complications 
Status asthmaticus (life-threatening) 
Respiratory failure 
Airway remodelling in chronic uncontrolled asthma 

Red Flags for Severe Asthma Attack 
PEFR <50% predicted 
Inability to speak in full sentences 
Cyanosis 
Silent chest on auscultation 

Key Points: 

Asthma is reversible airway obstruction, unlike COPD which is usually irreversible. 
Reversibility on spirometry is a hallmark for diagnosis. 
Inflammation is central—so ICS are the cornerstone of long-term therapy. 
Recognize triggers and risk factors. 
Acute management focuses on relieving bronchospasm and hypoxia. 

Further Suggested Reading: 
https://www.brit-thoracic.org.uk/quality-improvement/clinical-resources/asthma/bts-asthma-care-bundles/