Pulmonary

Asthma: Diagnosis and Classification

CLINICAL ACTIONS:

Asthma is a common lung disorder characterized by chronic airway inflammation, which causes the bronchi to swell and narrow the airways (bronchospasm), causing reversible, recurrent airway obstruction. Patients can experience episodic exacerbations (or attacks) that can be severe and even life-threatening. History and physical are important, not only for making the diagnosis, but also to help guide classification which is essential for the management plan. Spirometry should be used in all patients >5 years of age to confirm the diagnosis.

History: Key Elements

Wheezing
Shortness of breath
Difficulty breathing
Chest tightness
All symptoms but especially coughing are often associated with:
- Timing: at night or on waking, sometimes with menstrual cycle
- Exercise
- Laughing/crying
- Smoke
- Allergens (mold, animal fur, pollen)
- Extreme heat/cold
- Viral infections
Symptoms may interfere with normal activities
Symptoms typically variable over time and in intensity
More difficult to diagnose with patients already on inhaled corticosteroid (ICS) treatment
Physical Exam
Auscultation: Listen for the following:
- Expiratory wheezing (though in extreme causes this might be absent due to severely reduced airflow)
- Note crackles and inspiratory wheezing are not features of asthma
- Normal exam (often)
Other clinical findings: Include assessment of the following
- ENT: Ears, nose, throat for swelling, drainage due to allergy and/or inflammation
- Chest: Hyper expansion of thorax (especially children)
- Skin and eyes: Atopic dermatitis | Eczema | Evidence of allergic condition

Pulmonary Function Tests

Spirometry

Test used for both diagnosis and monitoring
Normal FEV1 score: ≥80% of predicted value
FEV₁ < 60% identifies patients at risk of asthma exacerbations, independent of symptom levels
- Tests the forced expiratory volume of air that can be exhaled during forced breath
  - FEV₁ (forced expiratory volume): Volume exhaled in the first second
  - FVC (forced vital capacity): Total volume exhaled after a deep breath
  - FEV₁/FVC ratio: When FEV1 <80% of FVC, suspicious for obstructive rather than restrictive lung disease (more likely to decrease proportionally)
  - If FEV₁ increases ≥12% and ≥200 mL from baseline after bronchodilator indicative of reversible airway obstruction

Fractional Exhaled Nitric Oxide (FeNO)

FeNO testing measures the nitric oxide, a byproduct of inflammation, in exhaled breath
May be useful in diagnosing, managing and predicting future exacerbations in some types of asthma
May be used as an adjunct to the evaluation process

Notes: FEV6 (volume after 6 seconds) can be considered rather than FVC in adults for whom full exhalation may take several seconds and be associated with light headedness | There are contraindications to spirometry (e.g., unstable cardiac disease or recent MI, aneurysms, recent thoracic or abdominal surgery, active viral infection, unexplained hypertension) | pre and post bronchodilator testing may be done in pulmonologist practice

Allergy Testing for precipitating factors

Consider referral for allergy testing if possibility that patient has allergies which may precipitate asthma (e.g., cats, dogs, medications)

Chest X-Ray: Key Findings

Typically, won’t show any abnormality
Important for assessment of other causes of respiratory disease, or other causes of exacerbation and/or worsening symptoms (e.g., pneumonia | foreign body in airways)

SYNOPSIS:

While targeted questions and examination are helpful, a good overall history and physical remain important to identify co-morbidities (e.g., sinusitis, rhinitis, GERD, other respiratory disorders, obstructive sleep apnea). It is also important to remain cognizant that multiple external factors can trigger an attack, including respiratory infections, smoking, allergies, exposure to cold or humid air, pollution, exercise, severe emotional and/or physical stress. Spirometry is currently the primary diagnostic tool for asthma.

KEY POINTS:

Severity of Asthma

Asthma severity is determined by the following
- Reported symptoms over the previous two to four weeks
- Standardized questionnaires – e.g., the Asthma Control Test
  - Provides numerical score to determine if the symptoms are well controlled
Current level of lung function: PEFR | FEV₁ | FEV₁/FVC
Number of exacerbations requiring oral glucocorticoids in the previous year

Types of Asthma

The historic categories of “intermittent,” “mild persistent,” “moderate persistent,” and “severe persistent” are no longer being used. Instead, GINA 2025 recommends assessing asthma severity based on symptom control and risk of adverse outcomes.

Mild Asthma

Defined as asthma that is well controlled with low-intensity treatment (as needed low dose ICS-formoterol OR low-dose ICS plus as-needed SABA)
The historic distinction between mild intermittent and mild persistent are no longer considered useful. GINA recommends against prescribing SABA-only (e.g. albuterol) treatment.
Prescribe a combined ICS-formoterol inhaler as-needed for patients with mild symptoms instead. Evidence shows reductions in exacerbations with this treatment.
Avoid reliance on SABA as main asthma treatment

Moderate Asthma

Defined as asthma that is well controlled with low- or medium-dose maintenance ICS-LABA Severe Asthma

Defined as asthma that requires high-dose maintenance ICS-LABA OR remains uncontrolled despite this treatment.

When to refer to pulmonologist and/or allergist/ immunologist

Difficulty confirming the diagnosis
Suspected occupational asthma requiring confirmatory testing
Persistent or severely uncontrolled asthma or frequent exacerbations
History of near-fatal asthma exacerbation (ICU admission or mechanical ventilation) at any time in the past
Evidence, or risk of, significant treatment side effects or need for long-tern corticosteroid use

Learn More – Primary Sources:

GINA: Global Strategy for Asthma Management and Prevention (2025 update)

US DOH: Focused Updates to the Asthma Management Guidelines (2020)

ATS: Asthma Center