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 symptom patterns (wheezing, shortness of breath, chest tightness, or cough that are variable, intermittent, and trigger-provoked) combined with objective spirometry demonstrating reversible airflow obstruction in patients 5 years and older. 1

Clinical Features That Establish Suspicion

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

• Variable and intermittent symptoms including wheezing, recurrent cough, shortness of breath, or chest tightness 1
• Trigger-provoked symptoms from exercise, allergens, viral infections, cold air, or irritants 1
• Nocturnal worsening of symptoms 1
• Polyphonic wheezing with exercise is a cardinal sign 2

Critical caveat: Physical examination may be completely normal between episodes, and normal findings do not exclude asthma. 1 This is a common pitfall—clinicians must not rely on physical examination alone to rule out the diagnosis.

Essential History Components

Document the following specific elements 1:

• Pattern of symptoms and their variability
• Precipitating factors and triggers
• Personal or family history of asthma, eczema, or allergic rhinitis
• Previous medication responses
• Focus physical examination on upper respiratory tract, chest, and skin 1

Objective Testing: The Diagnostic Cornerstone

Spirometry is required for diagnosis in all patients 5 years or older because medical history and physical examination alone are unreliable for establishing the diagnosis or excluding other conditions. 3

Spirometry Protocol

• Measure FEV1 and FEV1/FVC ratio 1
• Document reversibility: Improvement in FEV1 ≥12% and ≥200 mL after bronchodilator administration confirms the diagnosis 3
• Spirometry is preferred over peak flow meters due to wide variability in peak flow devices and reference values 3

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. 1

When Spirometry is Normal or Unavailable

If spirometry is normal or near-normal but asthma is still suspected 3:

• Bronchoprovocation testing with methacholine, histamine, cold air, or exercise challenge 3
• A positive test confirms airway hyperresponsiveness (characteristic of asthma but can occur in other conditions) 3
• A negative test is more helpful to rule out asthma 3
• Peak expiratory flow (PEF) monitoring showing serial variability when spirometry is unavailable 1

Differential Diagnosis: What to Exclude

Recurrent cough and wheezing are most often caused by asthma, but significant alternative diagnoses must be considered 3:

In Children

• Foreign body in trachea or bronchus 3
• Vocal cord dysfunction 3
• Vascular rings or laryngeal webs 3
• Laryngotracheomalacia, tracheal stenosis, or bronchostenosis 3
• Aspiration from swallowing dysfunction or gastroesophageal reflux 3

In Adults

• COPD (chronic bronchitis or emphysema) 3
• Congestive heart failure 3
• Pulmonary embolism 3
• Mechanical airway obstruction (benign and malignant tumors) 3
• Cough secondary to ACE inhibitors 3
• Vocal cord dysfunction 3

Continuous productive cough suggests other conditions like bronchiectasis, COPD, or chronic bronchitis rather than asthma. 2

Additional Testing When Indicated

• Chest radiography to exclude other pathology 1, though normal chest X-ray between episodes does not exclude asthma 2
• Additional pulmonary function studies if questions about COPD (diffusing capacity), restrictive defect (lung volumes), or vocal cord dysfunction (inspiratory flow-volume loops) 3

Common Diagnostic Challenges

Cough Variant Asthma

• Cough can be the principal or only manifestation, especially in young children 3
• Diagnosis confirmed by positive response to asthma medications 3
• Peak flow monitoring or bronchoprovocation may be helpful 3

Vocal Cord Dysfunction (VCD)

• Can mimic asthma or coexist with it 3
• Asthma medications provide little to no relief of VCD symptoms 3
• Variable flattening of inspiratory flow loop on spirometry strongly suggests VCD 3
• Diagnosis requires vocal cord visualization during an episode 3
• Consider VCD in patients with difficult-to-treat, atypical asthma and in elite athletes with exercise-related breathlessness unresponsive to asthma medication 3

Children Ages 0-4 Years

• Diagnosis is challenging due to difficulty obtaining objective lung function measurements 3
• Avoid inappropriate prolonged therapy, but also avoid underdiagnosing by using vague labels like "wheezy bronchitis," "recurrent pneumonia," or "reactive airway disease" 3
• Chronic airway inflammation and structural changes characteristic of asthma can develop in this age group 3

Comorbid Conditions

GERD, obstructive sleep apnea, and allergic bronchopulmonary aspergillosis may coexist with asthma and complicate diagnosis. 3