Stridor is a high pitched, harsh, vibratory noise caused by partial airway obstruction, which results in turbulent airflow. Stridor is typically heard on inspiration, but can also be heard on expiration and may also be biphasic. Inspiratory stridor suggests an obstruction above the glottis, due to collapse of soft tissues with negative pressure created during inspiration. Expiratory
stridor indicates an obstruction in the lower trachea (intrathoracic trachea and lower bronchi). Biphasic stridor can indicate edema near the cricoid cartilage that surrounds the trachea and is indicative of a fixed caliber of airway unaffected by changes in intrathoracic pressure.
There are many different causes of stridor. Some of the causes are diseases, while others are problems with the anatomical structure of the child’s airway. The upper airway in children is shorter and narrower than that of an adult, and, therefore, more likely to lead to problems with obstruction. During childhood, stridor is usually caused by infection of the cartilage flap (epiglottis) that covers the opening of the windpipe to prevent choking during swallowing. It can also be caused by a toy or other tiny object the child has tried to swallow. Laryngomalacia is a common cause of a rapid, low-pitched form of stridor that may be heard when a baby inhales. This harmless condition does not require medical attention. It usually disappears by the time the child is 18 months old. Stridor causing dyspnea when the person is at rest is a medical emergency. In such cases, a tube may be inserted through the person's mouth or nose (tracheal intubation) or by a small surgical incision directly into the trachea (tracheostomy) to allow air to get past the blockage and avoid suffocation.
Treatment of stridor should be directed at underlying cause of disease. If severe airway obstruction or respiratory compromise is present, airway must be established with endotrachial intubation. Stridor caused by viral croup without respiratory distress often responds to humidified air. Iif there is respiratory distress, nebulized racemic epinepherine and steroids will often be helpful. Epiglottitis, now rare, is an emergent situation, as airway obstruction can progress rapidly. Intubation under anesthesia is warranted, and IV cefuroxime is given for empiric antibiotic coverage. Laryngomalacia usually resolves by 18 months.