| Suspected diagnosis | Signs and symptoms | Diagnostic evaluation |
| Acute | ||
| Asthma | History of recurrent wheeze, cough, at least partial response to bronchodilator | History, PFT with bronchodilators, empiric trial of bronchodilators, exercise or methacholine challenge testing, chest radiography only if atypical, skin (or in vitro) testing for aeroallergen sensitization if history suggests inhalant allergen triggers |
| Viral bronchiolitis | Prodrome with rhinitis, occurs in infancy and early childhood, seasonal pattern | History, age, season In selected cases: Rapid antigen testing (RSV, influenza), viral cultures, chest radiography |
| Foreign body | Sudden onset of coughing and wheezing | History, physical examination, chest radiography, rigid bronchoscopy |
| Chronic | ||
| Asthma | As above | As above |
| Tracheomalacia | Persistent wheeze, starts early in life, poor response to bronchodilators, varies with position and activity | History, fluoroscopy, flexible bronchoscopy or dynamic CT with airway protocol |
| Cystic fibrosis | Chronic productive cough, crackles, with or without clubbing, failure to thrive, recurrent respiratory infections | Sweat chloride test, genetic testing |
| Swallowing dysfunction | Neurologic abnormality (nonuniversal), choking with eating, symptoms exaggerated by feeding | Videofluoroscopic swallowing study (modified barium swallow) |
| Gastroesophageal reflux | Symptoms sometimes related to eating, vomiting, refusal to eat, failure to thrive | 24-hour esophageal pH monitoring, multichannel intraluminal impedance monitoring |
| Vascular ring or sling | Persistent symptoms, starts early in infancy, may be exaggerated by position, homophonous wheeze | Chest radiograph, MRI, or CT angiogram Barium swallow |
| Tracheal stenosis | Persistent symptoms, with or without stridor, homophonous wheeze | Chest radiograph, CT scan, bronchoscopy |
| Mediastinal nodes or mass | Persistent symptoms, localized wheezing, no response to bronchodilator, systemic symptoms of underlying disease | Chest radiograph, CT scan |
| Immunodeficiency | Recurrent sinopulmonary infections, crackles, FTT, clubbing | Immunoglobulins, vaccine responses |
| Primary ciliary dyskinesia | Persistent sinusitis and otitis media with draining ears, recurrent respiratory infection, wet cough with sputum production, crackles, clubbing, FTT | Ciliary biopsy, genetic testing, exhaled nasal nitric oxide (ENO) |
| Inducible laryngeal obstruction (vocal cord dysfunction) | Inspiratory stridor, poor response to bronchodilators, absent symptoms during sleep, teenage, exercise related | Exercise testing, pulmonary function tests, laryngoscopy while symptomatic |
| Bronchiolitis obliterans | History of predisposing disease, ie, viral infection or transplantation, dyspnea, persistent wheezing | Chest CT scan In rare cases: Lung biopsy is needed |
