Pulmonary · Topic 11 of 28

Asthma: Diagnosis & Maintenance

Pulmonary · obstructive airway disease

Asthma: Diagnosis & Maintenance

Confirm variable airflow limitation, then give every adult an inhaled steroid — never SABA alone. As-needed ICS-formoterol is the preferred reliever.

Key numbers

Spirometry shows reversible airflow limitationFEV₁ ↑ ≥ 12% and 200 mL

Well controlled: symptoms ≤ 2 days a week≤ 2 days/week

01 · The ruleNever treat adult asthma with SABA alone

Every adult and adolescent with asthma needs ICS-containing treatment: SABA-only therapy raises the risk of severe exacerbations and asthma death, even in mild or intermittent asthma.

02 · GiveAs-needed ICS-formoterol is the preferred reliever

Preferred reliever (GINA Track 1): as-needed low-dose ICS-formoterol (budesonide-formoterol) — alone in mild asthma, where it cuts severe exacerbations ≥ 60% versus SABA alone, and as maintenance-and-reliever therapy (MART) at higher steps.

03 · Defined bySpirometry shows reversible airflow limitation

Confirm asthma with spirometry before and after a bronchodilator: a low FEV₁/FVC that improves ≥ 12% and ≥ 200 mL (or > 10% of predicted by the 2022 ERS/ATS standard) shows variable airflow limitation.

What it is

Core idea

Severe asthma: uncontrolled on high-dose ICS-LABASevere asthma is asthma that stays uncontrolled despite adherence to optimized high-dose ICS-LABA with contributory factors managed, or that worsens when the dose is reduced.

Causes & risk factors

Why it happens

SABA overuse predicts exacerbations and deathExacerbation risk factors: SABA overuse (≥ 3 canisters a year), poor ICS adherence or technique, low FEV₁, high blood eosinophils, obesity and other comorbidities, prior intubation or ICU stay, and psychosocial problems.

Diagnosis & monitoring

Work-up

Well controlled: symptoms ≤ 2 days a week must knowWell-controlled asthma: daytime symptoms and reliever use ≤ 2 days/week, night waking ≤ 2/month, no activity limitation, FEV₁ or peak flow > 80% of best, and 0–1 exacerbations needing oral steroids per year.

Management

Orders

Check inhaler technique and adherence before stepping up must knowBefore stepping up, confirm the symptoms are asthma and correct the common causes of poor control: inhaler technique, adherence, trigger exposure (allergens, smoke) and comorbidities such as obesity, rhinitis, GERD and OSA.

Not well controlled: step up and recheckNot well controlled: step up 1 step and reassess in 2–6 weeks. Very poorly controlled: step up 1–2 steps, consider a short oral steroid course and reassess in 2 weeks.

Step down after 3 months of controlOnce asthma has been well controlled for 2–3 months, step down gradually to the lowest effective dose with close monitoring — but do not completely withdraw the inhaled steroid.

MART maximum: 12 budesonide-formoterol inhalations a dayThe maximum total budesonide-formoterol dose on any single day (maintenance plus reliever) is 12 inhalations for adults and adolescents (54 mcg formoterol); this is a ceiling, not the expected use.

Add tiotropium to ICS-LABA at step 5For asthma uncontrolled on medium–high-dose ICS-LABA, add a long-acting muscarinic antagonist (tiotropium soft-mist inhaler), which improves lung function and reduces exacerbations, and refer for severe-asthma phenotyping.

Biologics match the phenotype: IgE, IL-5, IL-4RSevere asthma biologics: omalizumab (anti-IgE, allergic asthma with high IgE); mepolizumab, reslizumab, benralizumab (anti-IL-5/IL-5R, eosinophilic); dupilumab (anti-IL-4Rα); tezepelumab (anti-TSLP). Anaphylaxis can occur with any dose.

Normal spirometry: methacholine challengeWith normal spirometry but suspected asthma, a methacholine challenge FEV₁ fall ≥ 20% supports asthma; a negative test makes it unlikely. Avoid it if FEV₁ < 50% predicted or < 1 L.

Red flags & don'ts

Avoid harm

Never give a LABA without an inhaled steroid avoidLong-acting beta-agonists (salmeterol, formoterol, vilanterol) are always paired with an inhaled glucocorticoid in asthma — never used as monotherapy.

Inhaled steroids cause thrush: spacer and rinse complicationInhaled glucocorticoids cause dysphonia and oral candidiasis — prevent with a spacer and rinsing or gargling after each dose; high doses can suppress the adrenal axis and promote osteoporosis and cataracts.

Commonly confused

Tell apart

DLCO is normal in asthma, low in emphysemaDLCO is normal or slightly high in asthma but usually reduced in COPD with emphysema; asthma–COPD overlap combines persistent obstruction with asthma features such as eosinophilia and partial reversibility.

More detail

Reference

Show 6 reference facts

FeNO > 50 ppb in a steroid-naive patient supports allergic (type 2) airway inflammation; < 25 ppb points to another diagnosis; 25–50 ppb is indeterminate.

Asthma that will not control: look for vocal cord dysfunction (flow-volume loop), allergic bronchopulmonary aspergillosis, bronchiectasis, alpha-1 antitrypsin deficiency, COPD overlap or heart failure.

Aspirin-exacerbated respiratory disease: avoid aspirin and NSAIDs (celecoxib is usually tolerated); leukotriene receptor antagonists blunt the reaction and desensitization is an option.

Mepolizumab (anti-IL-5) is effective when blood eosinophils exceed 150/µL; it has been linked to herpes zoster, so give zoster vaccine before starting when possible.

In pregnancy, uncontrolled asthma is more dangerous to mother and fetus than asthma medicines; normal PaCO₂ in pregnancy is about 32 mmHg, so a value near 40 signals CO₂ retention.

Give every patient a written asthma action plan, inhaler-technique training and self-monitoring of symptoms or peak flow; repeat spirometry every 1–2 years.

Pearl

A SABA without an inhaled steroid treats the symptom and leaves the inflammation — and the risk of a fatal attack — untouched.

Sources · Merck Manual Professional — Asthma · Impact of new ERS/ATS bronchodilator reversibility interpretation on asthma diagnosis (2025) — PMC12442436 · Reddel HK et al. Global Initiative for Asthma Strategy 2021: executive summary and rationale for key changes. Eur Respir J 2022 · Merck Manual Professional — Pharmacologic Treatment of Asthma · IPU Review — Asthma update: GINA 2025 guidelines (Track 1 / Track 2 summary) · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).