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Key Features

Essentials of Diagnosis

  • New onset stridor in the setting of an upper respiratory illness or fever

General Considerations

  • Affects young children 6 months to 5 years of age in the fall and early winter

  • Most often caused by parainfluenza virus serotypes

  • However, many other viral organisms as well as Mycoplasma pneumoniae can also be causative

Clinical Findings

  • Usually a prodrome of upper respiratory tract symptoms is followed by a barking cough and stridor

  • Fever is usually absent

  • Patients with mild disease may have stridor when agitated

  • As obstruction worsens, stridor occurs at rest, accompanied in severe cases by retractions, air hunger, and cyanosis

  • Edema in the subglottic space accounts for the predominant signs of upper airway obstruction although inflammation of the entire airway is often present

  • Presence of cough and the absence of drooling favor the diagnosis of viral croup over epiglottitis


  • Radiography

    • Anteroposterior and lateral neck radiographs in patients with classic presentations are not required

    • However, can be diagnostically supportive if the film shows subglottic narrowing (the steeple sign) without the irregularities seen in tracheitis and a normal epiglottis


  • Mild croup requires supportive therapy with oral hydration and minimal handling

  • Conversely, patients with stridor at rest require active intervention

    • Oxygen should be administered to patients with oxygen desaturation

    • Nebulized racemic epinephrine (0.5 mL of 2.25% solution diluted in sterile saline) is commonly used because it has a rapid onset of action within 10–30 minutes

    • Both racemic epinephrine and epinephrine hydrochloride (L-epinephrine, an isomer) are effective in alleviating symptoms and decreasing the need for intubation

  • Dexamethasone, 0.6 mg/kg intramuscularly as one dose

    • Improves symptoms

    • Reduces the duration of hospitalizations and frequency of intubations

    • Permits earlier discharge from the emergency department

  • Oral dexamethasone (0.15 mg/kg) may be equally effective for mild to moderate croup

  • Inhaled budesonide (2–4 mg)

    • Improves symptoms

    • Decreases hospital stay

    • May be as effective as dexamethasone

  • In patients with impending respiratory failure, an airway must be established

    • Intubation with an endotracheal tube of slightly smaller diameter than would ordinarily be used is reasonably safe

    • Extubation should be accomplished within 2–3 days to minimize the risk of laryngeal injury

  • Tracheostomy may be required if patient is unable to be successfully extubated within 2–3 days



  • Most children have an uneventful course and improve within a few days

  • Patients with a history of croup associated with wheezing may have airway hyperreactivity


Petrocheilou  A  et al: Viral croup: diagnosis and a treatment algorithm. Ped Pulm 2014;49(5):421
[PubMed: 24596395] .

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