Asthma

An inflammatory disorder defined by both: respiratory symptoms (wheeze, shortness of breath, cough, chest tightness) that vary over time, and excessive variation in lung function ('variable airflow limitation'). In young children where lung function testing is not feasible, asthma is defined by the presence of variable respiratory symptoms alone. Chronic asthma pathology: mucosal infiltration with inflammatory cells (especially eosinophils), airway hyper-responsiveness, and intermittent airway narrowing (bronchoconstriction, mucosal congestion/oedema, or a combination).

• Classic symptoms: wheezing, coughing (chronic, especially at night), chest tightness, breathlessness — asthma is likely if more than one is present
• Supporting features: recurrent/seasonal symptoms, worse at night or early morning, history of allergies, family history of asthma/allergies, widespread audible wheeze, rapid relief with SABA
• In children: most present with cough; wheezing under 12 months is usually viral bronchiolitis, not asthma (do not use asthma medication in this age group); wheeze in children 1-5 years is also usually viral but may be asthma onset; more likely with recurrent nocturnal cough or cough after exercise, absence of viral symptoms, and personal/family history of atopy
• Trigger factor checklist (mnemonic): Allergens (pollens, animal dander, dust mites, mould); Bronchial infection; Cold air/exercise; Drugs (aspirin, NSAIDs, beta blockers); Emotion/psychosocial stress, laughter; Food (sodium metabisulphite, seafood, nuts, MSG); Gastro-oesophageal reflux; Hormones (pregnancy, menstruation); Irritants (smoke, perfumes, smells); Job (wood dust, flour dust, isocyanates, animals)

• Chest exam may be entirely normal between attacks — absence of signs does not exclude asthma
• During an attack: diffuse high-pitched wheezes throughout inspiration and most of expiration, usually prolonged
• If no wheeze on tidal breathing, it may appear after forced expiration or 1-2 minutes of exercise — but wheeze does not necessarily indicate asthma, and its absence in a breathless person is a serious sign

• Spirometry (FEV1/VC ratio) — Key investigation; <75% indicates obstruction. Recommended for most adults and children >6 years.
• Peak expiratory flow rate (PEFR), pre/post SABA — Characteristic improvement >15% in FEV1/PEFR supports diagnosis; also used for self-monitoring against a personal best, though it is not a substitute for spirometry

• Bronchial provocation testing (histamine/methacholine/hypertonic saline) — Rarely required; done in a respiratory lab to confirm diagnosis when uncertain
• Fractional exhaled nitric oxide (FeNO) — Adjunct marker of eosinophilic airway inflammation
• Exercise challenge — May help confirm diagnosis, especially in children
• Allergy testing — If an allergic trigger is suspected
• Chest X-ray — Not routine — unhelpful unless looking for another specific diagnosis (e.g. pneumonia) or symptoms unexplained by asthma

• Starting treatment: confirm the diagnosis; assess recent control and risk factors; treat moderately severe inflammatory airway disease with ICS to avoid fixed irreversible obstruction from submucosal fibrosis; avoid LABA monotherapy without ICS — associated with increased risk of asthma death; document evidence, set goals collaboratively, provide written information, educate and review regularly
• Goals: absent/minimal day and night symptoms; best possible lung function (>80% predicted); no limitation of sport/activity; control using regular anti-inflammatory medication plus relieving SABA when necessary
• Long-term goals: least drugs/doses/side effects that maintain control; reduce risk of fatal attacks; reduce risk of irreversible abnormal lung function
• Three-step ongoing plan: (1) assess symptom control over the previous 4 weeks and risk factors — exclude poor adherence, poor inhaler technique, wrong device, or an alternative/comorbid diagnosis before intensifying treatment; (2) treat and adjust to achieve good control — most patients achieve control with low-dose ICS, trial low-dose ICS before fixed ICS/LABA combinations, reserve ICS/LABA as a later option (too readily used in Australia), step down where appropriate; (3) review response and monitor to maintain control

Indications for starting preventive therapy (adults and children): SABA needed >2 days/week or >1 canister per 3 months (excluding pre-exercise); non-exercise symptoms >2 times/week between attacks; any night-time/waking symptoms; spirometry showing reversible airflow obstruction in asymptomatic phases; asthma significantly limiting physical activity despite appropriate pre-treatment; attacks ≥twice per month; or infrequent but severe/life-threatening attacks.

• Common reasons for suboptimal control: poor adherence; inefficient inhaler technique; procrastination introducing optimal therapy; failure to prescribe preventers (especially ICS) for chronic asthma; using bronchodilators alone and repeating without review; reliance on inappropriate alternative therapies
• Patient fears driving non-adherence: concerns about corticosteroids, overdosage, developing tolerance, embarrassment, peer group condemnation
• Check for contributing medical factors: obesity, rhinosinusitis, GORD, sleep apnoea, vocal cord dysfunction, smoking/COPD
• Faulty inhaler technique occurs in at least one-third of users; with faulty technique up to 90% of medication sticks to the mouth and never reaches the lungs — check technique regularly, at every review

Wean inhaled corticosteroids to the minimum dose needed to maintain adequate control. ICS have a flat dose-response curve — diminishing returns above beclomethasone/budesonide 1000mcg/day or fluticasone 500mcg/day. Step down when safe to do so.

1. Step 1 (few patients): as-needed SABA alone
2. Step 2 (most patients): regular daily low-dose ICS + SABA reliever as needed, OR as-needed budesonide-formoterol
3. Step 3 (some patients): regular daily low-dose ICS-LABA combination + SABA as needed, OR regular ICS (low-medium dose) + as-needed budesonide-formoterol
4. Step 4 (few patients): regular daily ICS-LABA (medium-high dose) + SABA as needed, OR regular ICS-formoterol maintenance-and-reliever therapy (medium dose)
5. Step 5 (few patients, add-on specialised treatment): consider add-on therapies (e.g. tiotropium) and specialist referral
6. All patients: assess individual risk factors and comorbidity, advise/prescribe a reliever at all times, provide education and a personalised written asthma action plan

Failure to recognise a developing severe attack has cost lives — a severe attack can start suddenly, even in those with previously mild asthma.

• Seek specialist advice for children under 6 months of age
• Bronchodilators (inhaled or oral) are ineffective under 12 months — wheeze at this age is usually viral bronchiolitis, not asthma
• A diagnosis of asthma should not be made if cough is the only/predominant symptom with no signs of airflow limitation; any diagnosis of asthma in a young child needs revisiting over time
• Delivery device by age: MDI alone suitable from ~8y; MDI + small volume spacer + face mask under 2-4y; MDI + large volume spacer 2-7y; nebuliser/compressor/face mask any age; dry powder inhalers generally not practical under 7-8y (Turbuhaler)
• Non-steroidal options (montelukast, SCG/nedocromil) are the prophylactic drugs of choice for mild-moderate chronic childhood asthma; if no response in 4 weeks consider ICS, weighing risks/benefits — doses ≥400mcg can cause growth and adrenal suppression; aim for the minimum maintenance dose (100-400mcg) that keeps the child symptom-free, then consider stepping down
• Stepwise plan — mild (infrequent, attacks >6-8 weeks apart): SABA prn. Moderate (attacks <6 weeks apart): SABA prn plus trial of montelukast or cromolyn or minimum-dose ICS. Severe (symptoms most days, nocturnal >1/week, multiple ED visits): referral, SABA prn, ICS, consider LABA+ICS combination (>6y), add nebulised ipratropium and oral prednisolone when required.

• Exercise-induced asthma prophylaxis: SABA 2 puffs 5 minutes before exercise (lasts 1-2h); LABA (salmeterol/eformoterol) more effective if used with ICS; SCG/nedocromil 2 puffs beforehand; combination SABA+SCG 5-10 minutes beforehand; montelukast 10mg (less in children ≥2y) daily or 1-2h beforehand; a non-drug warm-up program is often recommended by paediatricians as an alternative
• Thunderstorm asthma: high winds before a storm can rupture rye grass pollens, releasing allergens that trigger attacks — those with a history of allergy and poorly controlled asthma are most vulnerable. At-risk people should stay inside with windows/doors closed during storms, take preventer medication, follow their action plan, and keep reliever medication available. Those with seasonal allergic rhinitis can start intranasal corticosteroids before pollen season.
• Correct closed-mouth MDI technique: remove cap, shake vigorously 1-2s, hold upright; mouthpiece between teeth without biting, lips sealed; breathe out gently; tilt head back slightly; press the puffer once as you begin a slow deep breath in over 3-5 seconds; hold breath ~10 seconds; breathe out gently; repeat as required. Spacers overcome poor technique and reduce oropharyngeal deposition/irritation — particularly useful for adults struggling with MDI technique and children >3 years. Dip plastic spacers in water with detergent and air-dry (no rinsing/wiping) every 10 days or at least monthly.
• Antibiotics are not recommended for chronic asthma unless there is clinical evidence of super-respiratory infection.

• Children under 6 months of age — seek specialist advice
• Severe persistent asthma in children (symptoms most days, nocturnal symptoms >1/week, multiple ED visits)
• Step 5 — few patients needing add-on specialised treatment (e.g. tiotropium) beyond medium-high dose ICS-LABA
• Candidacy for anti-IgE monoclonal antibody therapy (specialist-initiated via PBS)
• Any acute severe/dangerous attack — ambulance/ED, not community management

• Provide every patient with a written, personalised asthma action plan — this measurably reduces asthma-related mortality and morbidity
• Teach the 4x4x4 first-aid rule and ensure reliever and (if applicable) spare prednisolone are available at home and anywhere the patient stays overnight
• Teach early warning signs of a severe attack and when to escalate to calling an ambulance
• Check inhaler technique at every review — faulty technique is common and can make effective medication appear to fail
• Advise at-risk patients (poorly controlled asthma, history of allergy) on thunderstorm asthma precautions during pollen season

• Asthma remains underdiagnosed and undertreated, and continues to cause an unacceptable number of deaths — the focus of management should be prevention; an acute attack represents failed treatment
• Objective measurement is superior to subjective assessment — spirometry is the key investigation, and PEFR has a role in self-monitoring
• Inhaled corticosteroids are the cornerstone of asthma treatment; prescribe at the lowest strength that works and do not reflexively re-prescribe combination/high-dose inhalers without regular review
• Avoid concomitant medications that can exacerbate asthma: beta blockers, aspirin, NSAIDs
• For breakthrough asthma or persistent poor control with poor compliance, consider switching to a combined ICS/LABA inhaler (e.g. Seretide Accuhaler, Symbicort) to simplify the regimen
• Most children are free of asthma by puberty; it typically develops between ages 2 and 7