TABLE 21-4.

Differentiating among Infectious Causes of Upper-Airway Obstruction^a

	Viral Laryngotracheitis35, 36, 37	Supraglottitis38, 39	Bacterial Tracheitis40, 41	Retropharyngeal Abscess38, 40, 42
History
Peak age	1–2 years	3–6 years, any	2–4 years, any	<3 years
Peak season	Late fall, late spring	Any	Late fall, late spring; any	Any
Prodrome	Viral illness	Uncommon	Viral illness	Uncommon
Onset of stridor	Gradual	Abrupt	Abrupt	Abrupt
Physical examination
Peak temperature (°C)	38–39	>39	>39	>39
Predominant findings	Brassy cough, stridor	Toxicity, stridor	Toxicity, stridor	Toxicity, stridor
Associated findings	Bark, rhinorrhea	Sore throat, odynophagia, dysphagia, anxiety, drooling	Brassy cough, anxiety	Lethargy
Voice	Hoarse, raspy	Normal, muffled, mute	Hoarse, raspy	Muffled, mute
Position	Any; thrashing	“Sniffing dog”; still	Any; thrashing	“Sniffing dog”; still
Airway occlusion	Predictable from degree of stridor	Sudden	Sudden	Sudden
Response to racemic epinephrine?	Yes, with rebound	No	No or partial	No
Laboratory tests
Peripheral neutrophils	Normal or low	High	Immature	Immature
Radiograph
Hypopharynx	Distended	Distended	Distended	Anteriorly displaced
Airway	Subglottic narrowing; edema cords	Swollen epiglottitis, aryepiglottic folds	Subglottic narrowing; irregular trachea ± intraluminal mass	Prevertebral soft-tissue mass with anterior displacement of airway (not valid sign if expiratory film, flexed neck)
Chest	Underaerated ± cardiomegaly	Underaerated ± cardiomegaly	Patchy parenchymal peribronchial infiltrate	Underaerated ± cardiomegaly
Endoscopy	Red, edematous subglottis; crusting pseudomembrane	Red, edematous supraglottic structures	Red, edematous, eroded trachea and bronchi; purulence, pseudomembrane	Bulging mass in posterior pharyngeal wall; purulence
Cause	Parainfluenza viruses (epidemic); other viruses (sporadic)	Streptococcus pyogenes, Streptococcus pneumoniae, Haemophilus influenzae b	Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae	Streptococcus pyogenes; Staphylococcus aureus; rare Streptococcus pneumoniae

^aSuperscript numbers indicate references.