Orientation notes for study. Doses and stepwise plans follow GINA and BTS/SIGN; check the Kenya MoH asthma guideline and the drugs available at your facility.
Definition
Asthma is a chronic inflammatory disorder of the airways causing recurrent episodes of wheeze, breathlessness, chest tightness and cough, with variable, reversible airflow obstruction and bronchial hyper-responsiveness.
Pathophysiology
- Airway inflammation (eosinophils, mast cells, Th2 lymphocytes, IgE) after exposure to a trigger.
- Bronchoconstriction (smooth muscle spasm), mucosal oedema, mucus plugging.
- Long term: airway remodelling (smooth muscle hypertrophy, subepithelial fibrosis) leading to partly fixed obstruction.
- Atopy (type 1 hypersensitivity) in most childhood and allergic asthma.
Risk factors and triggers
- Genetic: family history, atopy (eczema, hay fever), male in childhood.
- Triggers: allergens (house dust mite, pollen, pets, moulds), viral respiratory infections, exercise, cold air, smoke and biomass fuel, air pollution, NSAIDs/aspirin, beta-blockers, occupational agents, stress, GORD.
Clinical features
- Symptoms: episodic wheeze, cough (often at night or early morning), breathlessness, chest tightness; symptoms vary with time, triggers and season; improve with bronchodilators.
- Signs: may be normal between attacks; polyphonic expiratory wheeze, prolonged expiration, hyperinflation; in attacks, tachypnoea, tachycardia, accessory muscle use, pulsus paradoxus.
Diagnosis
- History of variable symptoms and triggers.
- Spirometry: FEV1/FVC below 0.7 with reversibility: FEV1 rise of 12% and 200 mL or more after a bronchodilator.
- Peak expiratory flow: diurnal variability above 20% over 2 weeks; low early morning "dips".
- Other tests: FeNO, skin-prick or specific IgE (allergy), blood eosinophils, bronchial provocation (methacholine), chest X-ray (to exclude other causes).
- Differential: COPD, heart failure ("cardiac asthma"), GORD, vocal cord dysfunction, bronchiectasis, foreign body, PE.
Assessing severity of an acute attack
| Level | Features |
|---|---|
| Moderate | PEF 50–75% of best, speech normal, RR below 25 |
| Acute severe | PEF 33–50%; RR 25 or more; HR 110 or more; cannot complete sentences |
| Life-threatening | PEF below 33%; SpO2 below 92%; silent chest, cyanosis, poor respiratory effort, bradycardia or hypotension, exhaustion, confusion, arrhythmia |
| Near-fatal | Raised PaCO2 and/or need for ventilation |
Management of acute severe asthma
- Oxygen (target SpO2 94–98%).
- Salbutamol 5 mg nebulised (repeat or continuous); add ipratropium 0.5 mg nebulised.
- Systemic steroid: prednisolone 40–50 mg orally (or IV hydrocortisone 100 mg), continued for 5–7 days.
- IV magnesium sulfate (1.2–2 g over 20 minutes) for severe or life-threatening attacks.
- Do not give sedatives. Check ABG (a "normal" or rising PaCO2 is dangerous), U&E (potassium).
- Chest X-ray if pneumothorax or pneumonia is suspected.
- Escalate: IV aminophylline or salbutamol, ICU, NIV/intubation.
- Before discharge: PEF above 75% of best, stable on inhalers for 24 hours; inhaler technique checked; written action plan; GP or clinic review within 48 hours; steroid course.
Long-term management (GINA stepwise)
- Aims: control symptoms, prevent exacerbations, keep normal lung function and activity.
- Preferred approach (GINA, track 1): low-dose ICS-formoterol as the reliever, with the same combination as maintenance at higher steps (MART).
- Alternative (track 2): ICS (for example beclomethasone) maintenance plus SABA (salbutamol) reliever.
- Step up as needed: low-dose ICS → ICS plus LABA → medium or high-dose ICS-LABA → add LAMA (tiotropium), leukotriene receptor antagonist (montelukast) → biologics (omalizumab, mepolizumab) in specialist care.
- Avoid SABA-only treatment; frequent reliever use signals poor control.
- Review: control, adherence, inhaler technique, triggers, comorbidity (rhinitis, GORD, obesity), step down after 3 months of good control.
- Non-drug: trigger avoidance, stop smoking, avoid biomass smoke, vaccinations (influenza, pneumococcal), asthma education and a personal action plan, regular exercise, weight loss.
Complications
- Status asthmaticus, respiratory failure, pneumothorax, pneumonia, lung remodelling with fixed obstruction, steroid side effects, death.
Exam points
- Reversible obstruction + diurnal variation + atopy.
- Silent chest, normal or rising PaCO2 = life-threatening.
- Treat acute severe asthma with oxygen, salbutamol, ipratropium, steroids, magnesium.
- ICS is the cornerstone of long-term control; LABA never used alone.
Pharmacology at a glance
Tap a drug name for its full card (how it works, adverse effects, cautions, dose), then use Back to this note to return to this spot. Condition guide: asthma drugs, first-line to add-ons.
| Drug | Class | Role here | Watch for |
|---|---|---|---|
| Salbutamol | Short-acting β₂-agonist | Rescue relief; nebulised in an acute attack | Tremor, palpitations, low potassium |
| Ipratropium | Antimuscarinic | Added to salbutamol in acute severe asthma | Dry mouth, urinary retention |
| Beclometasone | Inhaled corticosteroid | Preventer: the cornerstone of control | Oral thrush and hoarse voice (rinse the mouth) |
| Budesonide–formoterol | Inhaled steroid plus long-acting β₂-agonist | Preventer and, in MART, the reliever too | Never use a long-acting β₂-agonist alone |
| Montelukast | Leukotriene antagonist | Add-on, especially with allergic rhinitis | Sleep and mood change |
| Tiotropium | Long-acting antimuscarinic | Add-on in severe asthma | Dry mouth |
| Prednisolone | Systemic corticosteroid | Acute attacks, 5–7 days | High glucose, mood change, stomach irritation |
| Magnesium sulfate | Smooth-muscle relaxant | IV in severe or life-threatening attacks | Flushing, low blood pressure; check reflexes |
| Aminophylline | Methylxanthine | Specialist use in a refractory attack | Arrhythmia, seizures; check the level |
Avoid or take care: beta-blockers (even eye drops) can trigger severe bronchospasm, and aspirin and other NSAIDs worsen asthma in aspirin-sensitive patients.
Practice questions
1. A 19-year-old with asthma cannot complete sentences, RR 28, HR 118, PEF 40% of best. This is: A. Mild · B. Moderate · C. Acute severe · D. Life-threatening · E. Near-fatal Answer: C.
2. In a severe asthma attack the patient becomes drowsy with a silent chest and PaCO2 6.5 kPa. This indicates: A. Improvement · B. Impending respiratory failure (life-threatening) · C. Anxiety · D. Pneumonia · E. Pulmonary embolism Answer: B.
3. The most important drug for long-term control of persistent asthma is: A. Oral salbutamol · B. Inhaled corticosteroid · C. Oral antihistamine · D. Theophylline alone · E. Ipratropium alone Answer: B.