Viral most common; Viral Etiologies (PM AIR)
Parainfluenza(I (60%) >II>II),
Influenza A has been implicated in children with severe respiratory compromise
Peak age: 2nd year.
Croup typically occurs in children aged 6 months to 3 years. The mean age is 18 months.
Croup usually peaks over 3-5 days and resolves in 4-7 days
Gradual onset; begins with a prodrome of a few days of mild upper respiratory infection with coryza, nasal congestion, sore throat, and cough.
minimal fever; may have an insidious onset of fever (38-39°C) without toxicity
then, hoarse voice (not muffled) and harsh, brassy, barklike cough follow
Respiratory stridor usually develops at night, often awakening the child from sleep. Often, a harsh loud cough will awaken and frighten parents.
no drooling; no preference for sitting/leaning forward
Bacterial superinfection or bacterial tracheitis is uncommon. However, children who present a few days into the illness with acute onset of respiratory compromise that mimics epiglottitis have bacterial tracheitis until proven otherwise (aka Membranous croup).
In contrast to epiglottitis, dysphagia and drooling are not present.
These children present with an illness resembling viral croup; however, after several days when the child should be improving from the viral-like illness, high fever, toxicity, and worsening respiratory distress develop.
They usually do not respond to inhalation of racemic epinephrine.
mild cases, lung exam at rest - normal; however, mild expiratory wheezing may occur.
more severe: primarily inspiratory stridor at rest with nasal flaring, suprasternal and intercostal retractions. Air entry may be poor.
Lethargy or agitation may be a result of hypoxemia.
Other warning signs of severe respiratory disease are:
tachycardia that is out of proportion to presence of fever, lethargy, pallor, and hypotonia.
may be unable to maintain adequate oral intake resulting in dehydration.
cyanosis is a late ominous sign.
Pulse ox may be normal or slightly hypoxic in severe dz
In typical cases, radiographs are unnecessary unless the diagnosis is in question.
Lateral neck soft tissue: may show subglottic narrowing from soft tissue edema in severe disease; however, most of these radiographs are normal or show overdistention (ballooning) of the hypopharynx during inspiration.
AP neck will show narrowing of the laryngeal air column 5-10 mm below the level of the vocal cord (steeple sign) in 50-60% of cases.
Fiberoptic laryngoscopy usually reveals a pale and boggy
laryngeal mucosa. In bacterial tracheitis there is abundant purulent exudate
and pseudomembranes. In spasmodic croup, the mucosa is inflamed, erythematous
and with a velvety appearance.
Most children with croup have no stridors at rest and can be managed as outpatients. Gentle handling and avoidance of unnecessary painful procedures should be the rule because persistent crying increases oxygen demands and respiratory muscle fatigue.
Parents should provide humidified oxygen, especially at night, via a cool mist vaporizer. If not available, exposure to a steamed bathroom or the cool night air may alleviate some symptoms.
Vasoconstrictors: Used to decrease edema and dilate the larynx.
Racemic epinephrine is effective in reducing stridor in children with stridor at rest or in children with more severe symptoms who are not responding to humidified oxygen.
0.25-1 mL of a 2.25% solution in 3 mL of saline via a nebulizer;
<20 kg: 0.25 mL
20-40 kg: 0.5 mL
>40 kg: 0.75 mL
may repeat dose q20-30min in severe cases or q1-2h in moderate cases; the dose of L-isomer is 5 mL of a 1:1000 solution diluted in 2 mL of saline
racemic epinephrine (Vaponefrin, Racepinephrine) 2.25% -- Mixture of the D- and L- isomers of epinephrine. Causes adrenergic stimulation, which constricts precapillary arterioles, thereby decreasing capillary hydrostatic pressure. This leads to fluid resorption from the interstitium and improvement in the laryngeal mucosal edema, though its beta2 activity leads to bronchial smooth muscle relaxation. L-epinephrine in equal doses of the active L-isomer has been shown to have the same beneficial effects as racemic epinephrine. This finding is important because racemic epinephrine is not readily available outside of the US.
Effects last 2 h or less; previously feared rebound phenomenon appears quite uncommon, though some patients return to their baseline status after the effect of the drug wears off; some patients sustain improvement after racemic epinephrine, particularly if steroids are begun early, and may be discharged safely after a 3h observation; this period of observation is mandatory in all children who receive racemic epinephrine; hospitalize patients who were initially severely ill, responded incompletely, relapsed during the observation period, or required multiple doses; adverse effects include tachycardia, dysrhythmias, palpitations, hypertension, tremor, agitation, nausea, vomiting, and headache
Cool mist: Providing high humidity has not been proven to be effective except for one recent report, but seems to be beneficial to most children with croup.
It works by providing water droplets that penetrate the area of inflammation and add moisture to the mucosa.
Increasing humidity decreases the viscosity of the secretions in the trachea, which facilitates clearance from the airways.
Cool mist may activate mechanoreceptors in the larynx that produce a reflex slowing of respiratory flow rate.
Glucocorticoids -- Used to decrease airway inflammation. Routine use of corticosteroids in the management of croup remains controversial; however, they often are administered for severe, moderate, and even mild croup.
Dexamethasone 0.15 mg/kg is as effective as 0.3-0.6 mg/kg in relieving the symptoms from mild or moderate croup; however, no study compares the efficacy of parenteral versus oral corticosteroids.
0.15-0.6 mg/kg PO/IM as a single dose (max 8 mg); shown to reduce the overall severity within the first 4-24 h after injection; the long pharmacodynamic effects (54 h) makes only 1 injection necessary
Prednisone: 1-2 mg/kg/d PO for 5 d; not to exceed 60-80 mg/d
The use of inhaled corticosteroids, especially budesonide, has been shown to be effective.
Administration of 2 mg (4 mL) of nebulized budesonide qd prn has been shown to decrease the croup score substantially within 2-4 hours of administration when compared to nebulized saline. The increased cost of budesonide makes dexamethasone the corticosteroid of choice.
Severe croup that is unresponsive to therapy may require intubation. Intubate the patient with an endotracheal tube that is 0.5-1 mm smaller than predicted.
Other physicians have used a helium-oxygen (helium 60-80%) mixture in order to prevent intubation. Helium decreases the force necessary to move the gas through the airways and decreases the mechanical work of the respiratory muscles.
Indications for admission
Admit all children with severe croup to an intensive care unit for continuous monitoring and frequent suctioning to prevent airway obstruction.
Children with croup who also have any of the following conditions require hospitalization:
Persistent stridor at rest
Significant respiratory distress
A second doses of racemic epinephrine required
Incomplete response to racemic epinephrine
Poor social situation
http://www.emedicine.com/ped/topic510.htm. Up to date as of Sept 2004