Pediatric emergency medicine trisk 1488 1488

CHAPTER 75 ■ STRIDOR
ERIC C. HOPPA, HOLLY E. PERRY

INTRODUCTION
Stridor, although a relatively common occurrence, can be frightening to both
children and parents. The presence of stridor necessitates a complete and careful
evaluation to determine the cause of this worrisome and occasionally lifethreatening symptom. This chapter presents the causes of stridor and provides the
emergency clinician with guidelines for initial evaluation and management.

PATHOPHYSIOLOGY
Stridor is a respiratory sound caused by turbulent airflow through a partially
obstructed upper airway. Stridor can be inspiratory, expiratory, or biphasic
depending on the anatomic level of airway obstruction. Inspiratory stridor occurs
with obstruction of the extrathoracic trachea, biphasic stridor when the
obstruction is at the level of the glottis or subglottis, usually with a fixed
obstruction, and expiratory stridor when only the intrathoracic trachea is
involved. The pitch of the stridor also varies with the location of the obstruction.
Laryngeal and subglottic obstructions are associated with high-pitched stridor. In
contrast, obstruction of the nares and nasopharynx results in a lower-pitched
snoring or snorting sound called stertor. Because the passage of saliva and the
flow of air are impeded in pharyngeal obstruction, these patients often have a
gurgling quality of breathing. The relative length of inspiratory and expiratory
phases may be helpful in localizing the airway obstruction. Laryngeal obstruction
results in an increased inspiratory phase, whereas expiration tends to be
prolonged in bronchial obstruction. Both inspiratory and expiratory phases are
increased in patients with tracheal obstruction.

DIFFERENTIAL DIAGNOSIS
Stridor may occur in a wide variety of disease processes affecting the large
airways from the level of the nares to the bronchi, but most often arises with
disorders of the larynx and trachea ( Table 75.1 ). For the purposes of differential

diagnosis, it is helpful to categorize the common causes of stridor as acute or
chronic in onset and to further divide acute onset into febrile and afebrile causes (
Table 75.2 ). Life-threatening causes of stridor must be considered early during
the evaluation process ( Table 75.3 ).