Table 1.

Mechanisms of poor clearance of infection and pus in children.

External compression	Hilar adenopathy
	Tumors, cysts
	Vascular rings and slings
Endobronchial obstruction	Foreign body aspiration
	Endobronchial granuloma
Poor airway stability	Tracheo- and bronchomalacia (including TE fistula repair)
Congenital pulmonary airway malformations	Bronchial atresia, bronchial stenosis
	Congenital cystic adenomatoid malformation
	Intralobar sequestration, bronchogenic cyst
Micro-aspiration	Dysphagia syndromes
	Laryngeal cleft, TE fistula
Impaired cough	Neuromuscular weakness, impaired threshold to cough
Impaired cilia function	Cystic fibrosis (CF), ciliary dyskinesias
Impaired immune system	B-cell deficiencies (IgG deficiencies, IgG subclass deficiencies, IgA deficiencies), chronic granulomatous disease, combined variable immunodeficiency, and T-cell deficiencies
Abnormal mucus rheology	CF, ciliary dyskinesias
	Postinfectious bronchiectasis