Laryngotracheobronchitis (Croup)

CHAPTER 31

Laryngotracheobronchitis

(Croup)

Presentation

A child, most often between the ages of 3 months and 3 years (peak incidence 1 to 2 years, but can be seen up to 6 years), arrives with a characteristic “barking” cough that sounds very much like a trained seal. There is usually a prodrome of low-grade fever and symptoms of a mild upper respiratory infection. The barking cough tends to occur at night, with symptoms worsening on the second night.

The parents are usually alarmed by the sound of the cough, but the child is usually in no distress and appears nontoxic. The throat is clear and normal in appearance, and there may be varying degrees of stridor (predominately inspiratory) or retractions of the accessory chest muscles. Wheezes may be present on chest auscultation.

What To Do:

Perform a complete examination, with attention directed to the child’s throat. Although now rare in children, acute epiglottitis should be eliminated as a possibility by noting a healthy-appearing supraglottic region with absence of high fever, sudden onset, drooling, and laryngeal tenderness. At times, a normal-appearing epiglottis can be seen (Figure 31-1). There should also be no worsening of the child’s condition when lying supine.

Figure 31-1 A normal-appearing epiglottis.

Make the child as comfortable as possible, and avoid agitating the child with unnecessary procedures and examinations.

When available, monitor O₂ saturation with pulse oximetry or CO₂ level with capnometry. Humidified air or cool-mist therapy may be used, but neither has been proven to be effective.

Humidified oxygen should be administered to any patient with O₂ saturation less than 95%.

When the patient is showing any signs of distress, it is most appropriate to give a combination of nebulized racemic epinephrine and corticosteroid. Administer racemic epinephrine (Vaponefrin), 2.25% solution diluted in 3 mL of normal saline nebulized q4-6h (0.25 mL for infants younger than 6 months and weighing less than 20 kg; 0.5 mL for a child older than 6 months and weighing more than 20 kg). If no racemic epinephrine is available or if an inexpensive alternative is desired, 0.1 to 0.3 mL (0.01 mL/kg) of regular epinephrine (L-epinephrine) 1:1000 may be substituted for a racemic epinephrine and diluted in 3 mL of normal saline for nebulization.

An adjunct to treatment with epinephrine is the use of a continuous 70/30 helium and oxygen mixture (heliox) administered through a facemask.

Give dexamethasone (Decadron) elixir, 0.5 mg/5 mL, 0.6 mg/kg PO once (maximum dose 10 mg). If the patient is vomiting or unable or unwilling to take dexamethasone PO, it can be given IM as an injectable suspension, 8 mg/mL, or even nebulized in 3 mL of normal saline.

Observe the patient for signs of improvement or worsening over a period of 2 to 3 hours.

In general, admit all children with a toxic appearance, inability to keep down fluids with unreliable parents, or with no improvement with epinephrine administration or if worsening occurs at 2 to 3 hours following initial epinephrine administration.

For the mildest cases of croup, it is reasonable to treat with supportive measures alone. Adding one dose of dexamethasone to prevent worsening of symptoms later is also a justifiable addition. For moderate cases, and certainly for more severe cases, adding racemic or L-epinephrine is required to bring about the most rapid and effective relief.

What Not To Do:

Do not routinely obtain soft tissue neck radiographs. These should be reserved for atypical presentations when more severe disease (i.e., epiglottitis or abscess) or a foreign body is suspected. In croup, an anteroposterior soft tissue neck radiograph may show subglottic narrowing, which is called the steeple or pencil-point sign.

Do not separate the child with croup from the parents unless unavoidable. Any separation may increase anxiety and make breathing more difficult.

Do not routinely obtain blood work. The resultant pain and agitation will do more to worsen symptoms than is justified by the small potential for any useful information that might be obtained.

Do not prescribe antibiotics. This is a viral illness, and unless there is an alternative source of bacterial infection, antibiotic use will be ineffective and is inappropriate.

Do not discharge the patient prior to at least 2 hours of observation after racemic epinephrine has been administered. Although the theoretical rebound phenomenon has been discredited, patients might return to an unacceptable baseline.

Discussion

Laryngotracheobronchitis, or viral croup, is the most common infectious cause of acute upper airway obstruction in children. Most cases occur in the late fall and early spring. Parainfluenza viruses cause most cases of croup. Other responsible viruses include influenza A and B, adenovirus, respiratory syncytial virus, and rhinovirus. The viral infection leads to inflammation of the nasopharynx and subglottic area of the upper airway.

Stridor in children with croup occurs from the mucosal and submucosal edema of this subglottic portion of the airway, which is the narrowest portion of a child’s upper airway.

Not all children with stridor have croup. Excluding other causes, especially foreign body aspirations or ingestions, is crucial.

In contrast with viral croup, a nonseasonal allergic variant, known as spasmodic croup, may occur. This disorder typically has an abrupt onset, with no preceding upper respiratory infection and no fever. Spasmodic croup usually resolves quickly with exposure to humidified air, only to recur for the next few days.

When high fever, toxicity, and worsening respiratory distress develop after several days of crouplike illness, consider the possibility of the more serious but uncommon diagnosis of bacterial tracheitis.

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