The most common cause of acute upper airway obstruction is croup. Other causes include epiglottitis, foreign-body obstruction, peritonsillar abscess, bacterial tracheitis, and retropharyngeal abscess.
Upper airway obstruction may originate anywhere in the upper airway from anterior nares to subglottic region.
The clinician must maintain an awareness of the unique anatomic and physiologic characteristics of the respiratory tract in the growing infant and child in order to diagnose and manage upper airway emergencies.
Identifying the source for the respiratory distress, particularly differentiating between upper and lower airway pathologies, is a critical early step of the evaluation and management of these patients.
Key signs differentiating between upper and lower obstructive processes are wheezes and respiratory rate. Wheezes indicate lower airway obstruction and a very rapid respiratory rate; >40 breaths per minute indicate that the respiratory distress is not due to an upper airway obstructive pathology.
Acute upper airway emergencies are common in children and can result in significant morbidity and mortality. Calm, decisive, and deliberate intervention ensures the most effective outcome. Accurate assessment of the child in respiratory distress remains the most critical factor, and an expanded knowledge of the most frequent airway problems encountered will assist in the proper evaluation, treatment, and disposition.
The small caliber of the upper airway in children results in greater airway resistance and makes it vulnerable to occlusion. Any process that further narrows the airway will cause an exponential rise in airway resistance and will increase the work of breathing. As the child perceives distress, an increase in respiratory effort augments turbulence and increases resistance to an even greater degree.
Since the young infant is primarily a nasal breather, any degree of nasopharyngeal obstruction may result in significant increase in work of breathing. The large tongue of infants and small children can occlude the oropharynx, especially with altered mental status and decreased muscle tone. Interventions such as tilting the head or lifting the chin may be corrective. Insertion of an orotracheal or a nasotracheal airway may alleviate respiratory distress. Older children will frequently present with enlarged tonsillar and adenoidal tissues. The child’s trachea is easily compressible because of incomplete closure of the cartilaginous rings. Any maneuver that overextends the neck contributes to compression of this structure and secondary upper airway obstruction.
Abnormalities of respiratory function are eventually reflected in physical symptoms and signs ranging from subtle changes to obvious distress. Respiratory failure ensues when respiratory efforts cannot maintain oxygenation or ventilation.
Tachypnea represents the most common response of the child to increased respiratory needs. Although most commonly caused by hypoxia or hypercarbia, tachypnea may also be a secondary response to metabolic acidosis, pain, or central nervous system insult. Tachycardia represents a sign of distress of any etiology in children. This includes the patient with respiratory compromise.