Key Facts

Asthma is a chronic inflammatory disease of the airways characterised by variable symptoms of wheeze, breathlessness, chest tightness, and cough, with variable expiratory airflow limitation. Effective management focuses on achieving and maintaining control through a stepwise approach.

Epidemiology

• 5.4 million people in the UK; 1 in 11 children, 1 in 12 adults
• UK has among the highest prevalence and mortality rates in Europe
• 1,400 deaths/year in the UK (most preventable — NRAD 2014)
• Costs the NHS approximately £1.1 billion/year

Aetiology

• Complex interaction of genetic susceptibility and environmental factors
• Atopy (genetic predisposition to IgE-mediated hypersensitivity) is the strongest risk factor
• Triggers: allergens (house dust mite, animal dander, pollen, moulds), infections (viral URTI), exercise, cold air, pollution, occupational sensitisers, drugs (NSAIDs, beta-blockers), emotional stress

Pathophysiology

• Chronic eosinophilic airway inflammation driven by Th2 cytokines (IL-4, IL-5, IL-13)
• Airway hyperresponsiveness: exaggerated bronchoconstriction to stimuli
• Airway remodelling: smooth muscle hypertrophy, goblet cell metaplasia, subepithelial fibrosis, basement membrane thickening
• Reversible airflow obstruction: bronchospasm, mucosal oedema, mucus plugging
• Type 2 (T2-high) asthma: eosinophilic, responsive to ICS
• Non-T2 asthma: neutrophilic or paucigranulocytic, less responsive to ICS

Typical Symptoms

• Episodic wheeze (polyphonic, expiratory)
• Breathlessness
• Chest tightness
• Cough (particularly nocturnal or early morning)
• Symptoms variable, intermittent, worse at night/early morning
• Triggered by exercise, allergens, cold air, infections

Examination

• May be normal between attacks
• Widespread polyphonic wheeze on auscultation
• Prolonged expiratory phase
• Hyperinflation (if chronic)

Red Flags — Acute Severe/Life-Threatening Asthma

• Acute severe: PEF 33-50%, RR ≥25, HR ≥110, inability to complete sentences
• Life-threatening: PEF <33%, SpO2 <92%, silent chest, cyanosis, bradycardia, hypotension, altered consciousness, exhaustion
• Near-fatal: raised PaCO2 (normal or rising CO2 in acute asthma is a danger sign — indicates exhaustion)

Diagnostic Tests (NICE NG80)

1. FeNO (fractional exhaled nitric oxide): ≥40ppb in adults supports eosinophilic inflammation (first-line test)
2. Spirometry with reversibility: FEV1/FVC ratio reduced; ≥12% AND ≥200ml improvement post-bronchodilator
3. Peak flow variability: ≥20% diurnal variation over 2-4 weeks
4. Bronchial challenge testing (methacholine/histamine): if diagnostic uncertainty; PC20 <8mg/ml positive

Monitoring

• Asthma control questionnaire (ACT or RCP 3 questions)
• Peak flow diary
• FeNO monitoring (assess adherence to ICS)
• Spirometry annually

Bloods

• FBC (eosinophil count)
• Total IgE (if allergic asthma suspected)
• Specific IgE or skin prick testing (identify triggers)

Imaging

• CXR: usually normal; exclude differentials (pneumonia, pneumothorax, heart failure)
• HRCT: if bronchiectasis or alternative diagnosis suspected

Non-pharmacological

• Personalised asthma action plan: traffic light system (green/amber/red zones)
• Inhaler technique review: at every consultation (most common cause of poor control)
• Trigger avoidance: allergens, smoking (passive and active), occupational sensitisers
• Annual influenza vaccination: recommended for all asthma patients
• Weight loss: if overweight/obese
• Breathing exercises: Papworth, Buteyko

Pharmacological — BTS/SIGN Stepwise Approach (Adults)

• Step 1: SABA as needed (salbutamol 100mcg, 2 puffs PRN) — reliever only for infrequent symptoms
• Step 2: Low-dose ICS (beclometasone 200-400mcg/day or budesonide 200-400mcg/day)
• Step 3: Low-dose ICS + LABA (e.g. Seretide 100/50, Symbicort 200/6); OR increase ICS to medium dose
  • MART regime: Symbicort 200/6 — 1-2 puffs BD maintenance + 1 puff as needed (up to 12/day)
• Step 4: Medium-dose ICS + LABA; consider adding LTRA (montelukast 10mg ON), LAMA (tiotropium 2.5mcg), or theophylline
• Step 5: Specialist referral; high-dose ICS; oral prednisolone (lowest dose); biologic therapy for severe eosinophilic asthma
  • Omalizumab (anti-IgE, NICE TA278)
  • Mepolizumab (anti-IL5, NICE TA431)
  • Benralizumab (anti-IL5R, NICE TA565)
  • Dupilumab (anti-IL4R, NICE TA751)

Acute Asthma Management

• Oxygen: target SpO2 94-98%
• Salbutamol: 5mg via oxygen-driven nebuliser (back-to-back if severe)
• Ipratropium bromide: 500mcg nebulised (severe/life-threatening)
• Prednisolone: 40-50mg PO for 5-7 days (or IV hydrocortisone 100mg if unable to swallow)
• IV magnesium sulphate: 1.2-2g over 20 minutes (single dose for acute severe/life-threatening)
• IV aminophylline: specialist use for life-threatening asthma

Referral Criteria

• Specialist respiratory referral: diagnostic uncertainty, occupational asthma, severe/difficult asthma (step 4-5), frequent exacerbations despite adherence
• Emergency: acute severe or life-threatening asthma

• Well-controlled asthma: normal life expectancy and activity levels
• 1,400 deaths/year in the UK; 90% considered preventable (NRAD 2014)
• Key risk factors for asthma death: previous near-fatal attack, hospitalisation in past year, ≥3 drug classes, heavy SABA use (≥3 canisters/year), poor adherence to ICS, psychosocial factors
• Childhood asthma: 50-60% of children 'grow out' of asthma by adulthood, though airway hyperresponsiveness may persist
• SABA overuse (≥3 inhalers/year) is an independent risk factor for asthma death
• Biologic therapy: significantly reduces exacerbations and oral steroid use in severe eosinophilic asthma

RCP 3 Questions (Asthma Control)

Key NRAD (National Review of Asthma Deaths) Findings

ICS Dose Equivalence (BDP-HFA equivalent mcg/day)