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It is important to recognize the differences between the pediatric and adult upper airway to fully understand why even a relatively minor obstruction can cause significant airway compromise in children (Fig. 510-1). The pediatric airway is shorter and narrower and the larynx is placed more anterior than in adults.1 The narrowest portion of the pediatric airway is the subglottis, which is below the vocal cords. Therefore, mild edema in this region can result in a large reduction in the cross-sectional area of the airway. The resistance is inversely proportional to the fourth power of the radius of the airway (see Chapter 503). Therefore, even a small decrease in airway diameter leads to a much larger increase in resistance. Young children, and infants especially, have a large tongue in relation to the small oropharynx.1 They also have a larger epiglottis.1 Signs of partial inspiratory obstruction include stridor (a high-pitched sound heard on inhalation), hoarseness, and increased work of breathing (suprasternal and intercostal retractions).2 Stridor can be inspiratory or expiratory, depending on whether the obstruction is supraglottic or subglottic respectively. If the obstruction is severe or near-complete, worsening agitation, cyanosis, and respiratory failure will likely occur. Although acute stridor is usually infectious in etiology, other disorders may be present, especially when symptoms are severe or persistent. This chapter discusses inspiratory airway obstruction of infectious or noninfectious origin.

Figure 510-1.

Differences between the adult (left) and pediatric (right) upper airway.

(Finucane BT: Principles of Airway Management. Philadelphia, FA Davis, 1988.)

Noninfectious Causes of Upper Airway Obstruction

Laryngeal Anomalies

Disorders of the upper airway are also discussed in Chapter 371.

Laryngomalacia is the most common cause of noninfectious, persistent stridor in infants. It is characterized by a long, curved epiglottis that folds into an omega shape, with varying degrees of prolapse of the arytenoids during inspiration.3The flaccid supraglottic structures prolapse into the airway, leading to obstruction while breathing in. The inspiratory noise can begin in the first 2 months after birth, and it commonly presents as stridor that worsens with crying and activity; improvement occurs when the infant is placed in the prone position. Diagnosis is usually based on the history and physical examination; however, airway endoscopy is also helpful. The condition usually resolves spontaneously by 12 to 24 months. In more severe cases, surgery (supraglottoplasty) may be necessary.4 Gastroesophageal reflux disease (GERD), has been linked to laryngomalacia, and the possibility of concurrent reflux should be considered and treated.5 GERD can worsen the symptoms of laryngomalacia by contributing to further inflammation and edema of the larynx.

Laryngeal cysts, webs, laryngoceles, and saccular cysts are much less common conditions that can cause airway obstruction.4 Depending on the degree of obstruction, they can present soon after birth. Laryngeal ...

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