Am Fam Phys 2004;69:535; Nejm 1994;331:285, 322

Cause:Parainfluenza virus most commonly, respiratory syncytial virus (Respiratory Syncytial Virus Bronchiolitis), and others

Pathophys:Perhaps 2 types, or may be just 2 ends of a spectrum:

1. Acute laryngotracheitis follows 2-3 d of cold/cough
2. Spasmodic croup, sx without antecedents and probably represents a hypersensitivity reaction to a virus (Anesthesiol Clin N Am 1998;16:860)

Incidence 3/100 under age 6 yr, most age 1-3; 1.3% must be hospitalized; M > F (Jama 1998;279:1630)

Si:Barking cough (seal-like), tachypnea, hoarseness, inspiratory stridor, intercostal muscle retractions; when severe, cyanosis and/or altered level of consciousness

Vast majority are self-limited

r/o foreign body, epiglottitis, bacterial tracheitis (esp diphtheria), congenital anomaly (vascular ring etc.), whooping cough (Whooping Cough).

Xray:Soft tissue AP of neck shows “steeple sign,” a narrowing of air column in trachea as it approaches the larynx

Rx:

Humidified O₂, blow-by sufficient, mist tests/100% humidity provide no further rx benefit (Jama 2006;295:1274)

Racemic epinephrine by neb or IPPB q 2 h but watch for rebound; decreases stridor and retractions within 30 min (Peds 1992;89:302)

Steroids (BMJ 2000;319:595; Jama 1998;279:1630), at least for hospitalized pts or to prevent hospitalization but appears to also speed healing and help even mild cases (Nejm 2004;351:1306)

• Dexamethasone 0.3-0.6 mg/kg im/iv/po single dose
• Budesonide (Pulmicort) 2-4 mg in 4 cc neb; only half as effective as dexamethasone but still much better than placebo (Nejm 1998;339:498)