obstruction, upper airway anomalies (particularly laryngotracheomalacia), and congenital or postintubation subglottic stenosis Common causes for upper airway obstruction in infants and children include adenotonsillar hypertrophy, croup, foreign body, retropharyngeal abscess, and tracheitis Airway edema can be secondary to trauma, thermal or chemical burn, or anaphylaxis Epiglottitis or supraglotittis, although less common, can be one of the most life-threatening causes of respiratory distress and is a true emergency The incidence of epiglottitis has declined significantly since routine immunization against Haemophilus influenzae type b , the pathogen that once caused at least 75% of cases Streptococcus pneumoniae , group A streptococcus, Staphylococcus aureus , and nontypeable and other strains of Haemophilus influenza now account for most cases of bacterial epiglottitis Epiglottitis should be suspected in children who have abrupt onset of fever, sore throat, dysphagia, drooling, muffled voice, labored respirations, and/or stridor Young children appear toxic and anxious and assume a sniffing position with protruding jaw and extended neck These children are at risk of abrupt onset of respiratory arrest from obstruction Older children and adolescents may present with just severe sore throat, often with a less rapid progression, without oropharyngeal abnormalities Peritonsillar and retropharyngeal abscess may present with symptoms similar to epiglottitis but are less likely to have stridor and the onset is more gradual Croup or laryngotracheobronchitis is the most common cause of upper airway obstruction in children months to years of age Croup causes subglottic narrowing and is characterized by a barky cough, inspiratory stridor, and hoarseness that are worse at night Viral croup is most often caused by parainfluenza virus, frequently with preceding upper respiratory infection symptoms, which may or may not be accompanied by fever Respiratory distress often occurs with wakening during the night in a child who was relatively well before going to sleep Children with croup-like symptoms that are recurrent or prolonged may have an underlying fixed or functional airway abnormality, most commonly subglottic stenosis or hemangioma Children with chronic stridor, particularly those younger than years, may also have an underlying congenital anomaly Tracheitis, an infection of the trachea, may occur as a primary infection with abrupt onset, high fever similar to epiglottitis More commonly, it presents as a secondary infection in a child with an initial croup-like illness but with a worsening clinical course Although tracheitis is usually due to bacteria, most commonly streptococcus or staphylococcus, cases in which only viruses or no pathogen is identified are not uncommon Foreign-body aspiration, which has a peak age of occurrence of to years, may cause obstruction of the upper or lower airway and is a leading