What are the diagnostic criteria and treatment options for a patient presenting with recurrent episodes of wheezing, coughing, chest tightness, or shortness of breath, suspected of having asthma?

Diagnosis of Asthma

Asthma diagnosis requires documenting characteristic variable symptoms (wheezing, shortness of breath, chest tightness, or cough) combined with objective spirometry showing reversible airflow obstruction (FEV1 improvement ≥12% and ≥200 mL post-bronchodilator) in all patients 5 years and older. 1

Essential Clinical Features to Document

The diagnosis begins by identifying specific symptom patterns that distinguish asthma from other respiratory conditions:

• Variable and intermittent symptoms are the clinical hallmark—symptoms that fluctuate in intensity, occur episodically rather than continuously, and may completely resolve between episodes 1, 2, 3

• Trigger-provoked symptoms including exercise, allergens, viral infections, cold air, or irritants are characteristic features that help establish the diagnosis 2

• Nocturnal worsening of symptoms is a common and diagnostically useful pattern 1, 2

• Polyphonic wheezing with exercise is a cardinal sign of asthma 1

Critical caveat: Physical examination may be completely normal between episodes, and normal findings do not exclude asthma—this is a common diagnostic pitfall 1, 2

Mandatory Objective Testing

Spirometry is non-negotiable for diagnosis because medical history and physical examination alone are unreliable:

• Spirometry is required in all patients 5 years or older to establish the diagnosis, as clinical assessment alone cannot reliably confirm asthma or exclude alternative conditions 1, 2

• Diagnostic criteria on spirometry: Measure FEV1 and FEV1/FVC ratio, then document reversibility with FEV1 improvement ≥12% AND ≥200 mL after bronchodilator administration 1

• If spirometry is normal or unavailable: Proceed to bronchoprovocation testing with methacholine, histamine, cold air, or exercise challenge 1, 4

• Peak expiratory flow (PEF) monitoring showing variability can be used when spirometry is unavailable or repeatedly normal despite symptoms 2

Important limitation: Spirometry may be normal between episodes in mild asthma; if repeatedly normal despite symptoms, the diagnosis must be questioned but cannot be excluded based on this alone 2

Excluding Alternative Diagnoses

The differential diagnosis varies by age and must be systematically considered:

In children, consider 1:

• Foreign body in trachea or bronchus
• Vocal cord dysfunction
• Vascular rings or laryngeal webs
• Aspiration from swallowing dysfunction or gastroesophageal reflux

In adults, consider 1:

• COPD (especially in smokers or older patients)

• Congestive heart failure

• Pulmonary embolism

• Mechanical airway obstruction

• Cough secondary to ACE inhibitors

• Chest radiography should be performed to exclude other pathology, though a normal chest X-ray between episodes does not exclude asthma 1, 2

Additional Diagnostic Considerations

• Comorbid conditions such as GERD, obstructive sleep apnea, and allergic bronchopulmonary aspergillosis may coexist with asthma and complicate diagnosis 1

• Additional pulmonary function studies (diffusing capacity, lung volumes, or inspiratory flow-volume loops) may be indicated when the diagnosis remains uncertain or alternative conditions are suspected 1

• Document personal or family history of asthma, eczema, or allergic rhinitis, as well as medication responses to support the diagnosis 2

Diagnostic Algorithm

1. Document characteristic symptom patterns (variable, intermittent, trigger-provoked, nocturnal worsening) 1, 2
2. Perform spirometry with bronchodilator in all patients ≥5 years old 1, 2
3. If spirometry shows FEV1 improvement ≥12% and ≥200 mL post-bronchodilator, diagnosis is confirmed 1
4. If spirometry is normal but symptoms persist, proceed to bronchoprovocation testing 1
5. Obtain chest radiography to exclude alternative diagnoses 1, 2
6. Consider additional testing based on clinical context to rule out mimics 1, 2