Asthma

Related Subjects: |Asthma |Cystic Fibrosis |Sweat Test |Acute Severe Asthma |Exacerbation of COPD |Pulmonary Embolism |Cardiogenic Pulmonary Oedema |Pneumothorax |Tension Pneumothorax |Respiratory (Chest) infections Pneumonia |Fat embolism |Hyperventilation Syndrome |ARDS |Respiratory Failure

📖 Definition

• Asthma is a chronic inflammatory airway disorder with variable symptoms and variable expiratory airflow limitation (often reversible, but may become partly fixed with remodelling).
• Typical symptoms: episodic wheeze 🎶, cough, chest tightness, breathlessness; often worse at night/early morning and triggered by viruses, allergens, cold air, smoke or exercise.

💡 High-yield Asthma Acronyms to remember

• SABA = Short-Acting Beta₂-Agonist quick reliever. e.g. salbutamol
• SAMA = Short-Acting Muscarinic Antagonist such as ipratropium. Used particularly in acute severe asthma alongside SABA.
• LABA = Long-Acting Beta₂-Agonist e.g. formoterol or salmeterol. Usually used with inhaled corticosteroid
• ICS = Inhaled Corticosteroid. Preventer therapy that reduces eosinophilic airway inflammation and lowers the risk of exacerbations.
• PEF = bedside expiratory airflow measure using peak flow meter
• BDR = Bronchodilator Reversibility in spirometry
• FeNO = Fractional Exhaled Nitric Oxide eosinophilic/type 2 inflammation marker. Marker of type 2/eosinophilic airway inflammation. Can support asthma diagnosis and may predict steroid responsiveness.
• MART = Maintenance And Reliever Therapy one ICS/formoterol inhaler for maintenance + relief
• AIR = Anti-Inflammatory Reliever as-needed ICS/formoterol reliever strategy

🧬 Pathophysiology (bronchospasm and inflammation)

• Airway inflammation → oedema + mucus + bronchial hyperresponsiveness → airflow limitation and air-trapping.
• Common phenotype: Type 2 inflammation (eosinophilic/IgE-mediated): IL-4/5/13 → IgE switching + eosinophils → inflammation and exacerbation risk.
• Chronic poor control can cause airway remodelling (smooth muscle hypertrophy, goblet cell hyperplasia, subepithelial fibrosis) → less reversibility over time.

🫁 Types of asthma

• Extrinsic (allergic / atopic) asthma: commonly begins in childhood and is associated with type I hypersensitivity. It is driven by IgE-mediated immune responses to allergens such as house dust mite, pollen, animal dander, or mould. Patients often have a personal or family history of eczema, allergic rhinitis, or other atopic disease.
• Intrinsic (non-allergic) asthma: not clearly linked to atopy or a specific external allergen and is more likely to begin in adulthood. Triggers may include viral infections, cold air, exercise, stress, air pollution, gastro-oesophageal reflux, or irritants. The underlying problem is still chronic airway inflammation and bronchial hyper-responsiveness, even without an obvious allergic mechanism.

💡 In practice, this division is helpful for understanding pathophysiology, but many patients show overlap. Asthma is now better understood as a heterogeneous inflammatory airway disease with different phenotypes, including allergic, non-allergic, eosinophilic, and exercise-induced patterns.

⚡ Triggers & Risk Factors

• 🌫️ Tobacco smoke (including passive), pollution, cold air, strong odours, damp/mould.
• 🌿 Allergens: house dust mite, pets, pollens; consider ABPA if difficult asthma + Aspergillus sensitisation features.
• 🦠 Viral URTIs (major trigger), exercise, stress.
• 💊 NSAIDs/aspirin (esp. with nasal polyps), non-selective β-blockers.
• 🏭 Occupational asthma: suspect if adult onset + improves on days off/holidays (e.g., flour, isocyanates, cleaning agents).

🩺 Core Assessment (every consultation)

• Confirm diagnosis with objective testing where possible (don’t rely on symptoms alone).
• Control: daytime symptoms, night waking, activity limitation, reliever use, and exacerbations (oral steroids/ED/hospital).
• Risk: prior ICU/ventilation, frequent oral steroid courses, poor adherence, incorrect technique, smoking exposure, comorbidities.
• Comorbidities that worsen control: rhinitis/sinusitis, reflux, obesity, anxiety, OSA; consider vocal cord dysfunction, bronchiectasis.

Objective tests used to support an asthma diagnosis include: bronchodilator reversibility (BDR) with an FEV₁ increase of ≥12% and ≥200 mL from baseline (or ≥10% of predicted), peak expiratory flow (PEF) variability ≥20% over 2 weeks, and FeNO ≥50 ppb in adults (or ≥35 ppb in children aged 5–16). Obstructive spirometry may support the diagnosis, but FEV₁/FVC <0.70 alone does not confirm asthma, because obstruction can occur in other diseases such as COPD. Always interpret test results alongside a suggestive clinical history and remember that prior inhaled corticosteroid treatment can make spirometry and FeNO appear more normal.

🔎 Diagnosis - Adults (objective test–driven)

• Start with clinical suspicion (variable symptoms + triggers) then confirm objectively.
• Step 1 (Type 2 markers): measure blood eosinophils OR FeNO.
  • Diagnose asthma if eosinophils are above lab reference range OR if FeNO ≥ 50 ppb and history suggests asthma.
• Step 2 (airflow variability): spirometry with bronchodilator reversibility (BDR).
  • Diagnose if FEV1 increases by ≥12% and ≥200 mL (or ≥10% predicted) after bronchodilator.
• If spirometry is delayed/unavailable: PEF diary twice daily for 2 weeks.
  • Diagnose if PEF variability ≥20% (amplitude % mean).
• If tests are negative but suspicion remains high: refer for specialist assessment (e.g., bronchial challenge testing) and consider alternative diagnoses.

👶 Diagnosis - Children aged 5–16

• Use objective testing where possible (symptoms alone are not enough).
• FeNO first (if available): diagnose if FeNO ≥35 ppb with suggestive history.
• If FeNO not raised/unavailable: perform spirometry with BDR; if delayed, use PEF variability; consider allergy testing (skin prick/IgE/eosinophils) as supportive evidence.
• Children under 5: diagnosis is often clinical + response to treatment with careful review; always reconsider alternative diagnoses (e.g., viral episodic wheeze, airway anomalies, aspiration).

🧪 Baseline & “rule-out” Investigations

• FBC (eosinophils), FeNO (if available), spirometry/PEF as above.
• CXR is usually normal in asthma; consider if atypical features, focal signs, fever, haemoptysis, suspected pneumothorax, or poor response.
• Allergy testing if allergic phenotype suspected and results would change management (avoidance, rhinitis treatment, ABPA work-up).

🧠 Differential Diagnoses (don’t miss)

• COPD (progressive symptoms, smoking history, less variability; fixed obstruction).
• Inducible laryngeal obstruction / vocal cord dysfunction (inspiratory noise, throat tightness, poor response to bronchodilator).
• Heart failure (“cardiac wheeze”), pulmonary embolism, bronchiectasis, foreign body, dysfunctional breathing/anxiety.

🚑 Treatment of Acute Severe Asthma

Acute severe asthma is a medical emergency. Give oxygen, bronchodilators, and systemic steroids promptly, and reassess frequently. Escalate early if there are features of life-threatening asthma, poor response to initial treatment, rising carbon dioxide, exhaustion, or reduced consciousness.

🔎 Recognise severity

• Acute severe asthma (adult) is suggested by any of:
  • PEF 33–50% of best or predicted
  • Respiratory rate ≥25/min
  • Heart rate ≥110/min
  • Unable to complete sentences in one breath
• Life-threatening asthma features include:
  • PEF <33%
  • SpO₂ <92%
  • Silent chest, cyanosis, poor respiratory effort
  • Hypotension, arrhythmia, exhaustion
  • Confusion, drowsiness, coma
  • Normal or raised PaCO₂

⚡ Immediate treatment

1. Give oxygen to maintain saturations 94–98%.
2. Give high-dose inhaled/nebulised salbutamol promptly.
   • Usually 5 mg nebulised, driven by oxygen if needed
   • If milder or able to use an inhaler: repeated doses via MDI + spacer can also be effective
3. Add ipratropium bromide in acute severe or life-threatening attacks.
   • Typical adult dose: 500 micrograms nebulised
4. Give steroids early.
   • Prednisolone 40–50 mg orally as soon as possible
   • If unable to swallow: hydrocortisone 100 mg IV

📈 Monitoring and reassessment

• Check PEF, pulse, respiratory rate, SpO₂, ability to speak, and work of breathing.
• Repeat assessment frequently after initial bronchodilator treatment.
• Perform ABG if SpO₂ is <92%, if the patient looks exhausted, or if life-threatening asthma is suspected.
• A normal or raised PaCO₂ in acute asthma is worrying and may indicate impending respiratory failure.

🧪 If poor response or severe attack

• Repeat nebulised salbutamol as needed.
• Continue/add nebulised ipratropium.
• Consider IV magnesium sulfate:
  • 1.2–2 g IV over 20 minutes in adults with acute severe or life-threatening asthma not responding well to initial therapy
• Seek senior / critical care / anaesthetic support early if worsening, exhausted, hypercapnic, or deteriorating despite treatment.

🚨 Indications for ICU / urgent senior escalation

• Deteriorating PEF
• Persisting or worsening hypoxia
• Hypercapnia or acidosis
• Exhaustion, feeble respiration, silent chest
• Drowsiness, confusion, reduced consciousness
• Respiratory arrest or need for ventilatory support

🏥 Discharge and follow-up

• Do not discharge until clearly improving and safe.
• Ensure the patient has:
  • An ICS-containing preventer inhaler
  • Inhaler technique checked
  • A personalised asthma action plan
  • Smoking cessation support if relevant
  • Follow-up arranged after the attack

💡 Practical memory aid: Oxygen + Salbutamol + Ipratropium + Steroids, then reassess quickly. If response is poor, think magnesium, ABG, and early ICU/senior escalation.

🎯 Long-Term Management - Principles

• Address fundamentals before stepping up: confirm diagnosis, correct technique, adherence, trigger reduction, and treat comorbidities.
• Provide a Personalised Asthma Action Plan (PAAP) and teach when/how to escalate and when to seek urgent help.
• Arrange structured follow-up: at least annual review and after any exacerbation.

💊 Acute Asthma Management (UK, BTS/NICE/SIGN NG245) Age > 12

Children 5–11 years (stepwise)

• Stepwise approach includes paediatric low-dose ICS with reliever, step-up with add-ons and (in selected children able to use regimen safely) consideration of MART pathways per NG245 algorithm for 5–11.
• Always check technique/adherence and address triggers before escalating.

Children under 5

• Often symptom-pattern driven (viral episodic wheeze vs multiple-trigger wheeze); reassess diagnosis frequently.
• Typical approach: reliever therapy plus trial of regular paediatric low-dose ICS when indicated; consider LTRA trial in selected cases and stop if ineffective.

🧼 Non-pharmacological Management

• Smoking cessation (including household smoking); reduce damp/mould exposure; optimise rhinitis (intranasal steroid + antihistamine as needed).
• Vaccination and infection-avoidance advice in line with UK policy (flu/COVID as appropriate).
• Weight management, activity advice, and breathing pattern support where relevant.

🫁 Inhaler Technique - Practical, High-Yield

• Always observe technique (don’t just ask). Re-check at every review and after any exacerbation.
• Metered-Dose Inhaler (MDI) basics:
  • Shake well → breathe out fully → seal lips → start slow deep breath and press once → continue slow deep inhale → hold breath ~10 seconds → wait ~30–60 sec between puffs.
  • Common errors: firing too early/late, inhaling too fast, not shaking, not holding breath.
• Spacer (strongly preferred with ICS MDI):
  • Attach inhaler → press 1 puff into spacer → take slow deep breath (or 5 tidal breaths in children) → repeat for each puff (one puff at a time).
  • Clean spacer monthly (warm water + detergent), air-dry (reduces static), replace per manufacturer guidance.
• Dry Powder Inhaler (DPI):
  • Load dose correctly → breathe out away from device → fast and deep inhale → hold breath ~10 seconds.
  • Common errors: exhaling into device (clumps powder), inhaling too gently, poor seal.
• After any ICS dose: rinse mouth / brush teeth to reduce oral thrush and dysphonia.

🧾 Personalised Asthma Action Plan (PAAP) - what it must include

• Daily preventer plan (what to take when well) and how to check/track control.
• Worsening symptoms plan (what to increase, how often, and when to review).
• Emergency plan: clear red-flags and when to call 999/attend ED.
• For AIR/MART users: written instructions on using the ICS/formoterol inhaler as reliever during deterioration and thresholds for urgent care.

📅 Monitoring & Follow-up

• Primary care review at least annually and after any asthma exacerbation.
• At each review: confirm diagnosis if uncertain, assess control/risk, check technique + adherence, update PAAP, and rationalise inhalers.
• Consider PEF monitoring for people with poor perception of airflow limitation, frequent exacerbations, or for occupational patterns.

📚 NICE-aligned References

• NICE NG245 (BTS/NICE/SIGN): Asthma-diagnosis, monitoring and chronic asthma management (incl. Algorithms B/C/D/E).
• NICE CKS: Asthma-follow-up and acute exacerbation management.
• BNF (NICE): Acute asthma treatment summary.