Croup, Viral

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

Diagnosis

• 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

Treatment

• 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

Outcome

Prognosis

• 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

Reference