Table 2.

When to suspect specific alternative diagnosis and initial useful diagnostic examinations.

Alternative diagnosis	When to suspect	Useful diagnostic examinations
Cystic fibrosis and bronchiectasis	Daily cough productive of sputum, clubbing, malabsorption and failure to thrive, recurrent chest infections, airways bacterial colonization	Sweat chloride test, Genetic tests, Swab culture, Lung Function tests, Chest CT
Immunodeficiency	Recurrent airway infections, Systemic infections (from a few months of age)	Immunoglobulins and specific tests
Primary ciliary dyskinesia	Neonatal upper airway symptoms, Chronic rhinosinusitis, Recurrent otitis media, Daily wet cough, Laterality defects	Nasal NO, HSVM, EM, Genetic tests, Immunofluorescence, Chest CT
Protracted Bacterial Bronchitis	Cronich wet cough, Poor response to Beta-2 agonists, Good response to prolonged course of antibiotics	Often no need of examinations, Swab culture, Bronchoscopy with BAL
Airway malacia	Monophonic wheeze when the child is active, High risk setting (i.e., pt operated for tracheo-esophageal fistula or vascular ring), Presence of associated stridor	Lung function test (truncated expiratory flow in spirometry), Flexible bronchoscopy, Dynamic CT
Airway foreign body	Abrupt onset of symptoms, History of choking, Unilateral monophonic wheeze, Focal hyperinflation of lung	Bronchoscopy, chest x-ray
Habit cough	Prolonged dry, honking cough; Absence of cough during sleep; Absence of any physical findings	Medical investigations should be avoided
Vocal cord dysfunction	Absence of structural abnormalities, Sudden worsening of “asthma” symptoms, No response to asthma medications	Video of an attack, Laryngoscopy during attack
Bronchiolitis obliterans	History of severe viral respiratory infection in the first 3 years of life	CT scan (characteristic mosaic pattern and air trapping)

CT, computed tomography; EM, eletcron microscopy; HSVM, high speed video microscopy; NO, nitric oxide.