Respiratory distress is common in children. Airways obstruction is an event that can be precipitated acutely by infections, trauma, inhalational injury, a mass lesion, or foreign-body aspiration. Alternatively, an acute illness can significantly worsen an obstruction caused by either a chronic process or an anatomic abnormality. Acute upper airways obstruction presents an immediate threat to life. If the airways obstruction is relieved quickly, then rapid clinical improvement can be effected. Acute obstruction of the airways can occur throughout the respiratory tract. Knowledge of developmental respiratory physiology and anatomy, combined with historical information, can help determine the anatomic site of the obstruction. In the event of airways obstruction, definitive treatment and relief of the obstruction is of critical importance to prevent hypoxic-ischemic injury.

Airways obstruction results either from blockage of the airway from aspiration of a foreign object or can occur when the inner diameter of the airway is reduced, such as occurs with mucosal edema in the case of acute laryngotracheobronchitis, or with constriction of the peribronchiolar muscles, as occurs with status asthmaticus. Alternatively, the airway can be compressed from an external mass, such as a mediastinal tumor; the onset can seem to occur quite rapidly, even with a slowly growing tumor. A patient with chronic airways obstruction, such as a prematurely born infant, can experience acute airways obstruction caused by an acute viral infection, such as respiratory syncytial virus bronchiolitis.[1]

Infants have a greater incidence of respiratory compromise compared with older children because they have a smaller airway diameter and exponentially increased airway resistance. Second, the connective tissue in infants has incompletely hardened cartilaginous structures (malacia). Such is the case for the cartilaginous structures such as the larynx (epiglottis, aryepiglottic folds, arytenoid cartilage, tracheal cartilage), the trachea, bronchi, bronchioles, and the chest wall itself. As a result, any increase in airways obstruction results in relatively higher airflows, thereby increasing the dynamic obstruction caused by relatively flexible airway structures. In infants younger than 1 year, collateral lower airway circulation in the alveoli and the bronchioles, the pores of Kohn, and the canals of Lambert are absent, predisposing the infant to atelectasis. The narrowest portion of the airways in the infant and child is the cricoid ring, unless an infant is born with congenital airways anomalies such as tracheal stenosis or bronchomalacia. In the older child and adolescent the narrowest portion of the airway is the vocal cord aperture.[2]