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Croup is disease of upper airway inflammation of the larynx and subglottic airway most commonly caused by respiratory viruses (Parainfluenza 1, 2 & 3 are the most commonly isolated viruses). It most commonly occurs in 6 month to 6 year old children and is more common in boys (1.4:1 ratio).
Croup most commonly occurs in the fall - winter (parainfluenza type 1 seasonality). Visits to emergency departments are most common between 11p - 4a however, patient’s arriving earlier in the evening are more likely to be admitted.
The clinical presentation of croup is dependent on the level of upper airway obstruction caused by airway inflammation. Inspiratory stridor, "barking" cough (more common in children), and hoarseness (more common in adults) are the common symptoms associated with croup. Croup usually begins with URI sx (cough, congestion and rhinorrhea) and then progresses to symptoms of upper airway obstruction as the inflammation worsens. The respiratory distress associated with croup is directly related to the level of obstruction. Most symptoms resolved within 3 days, but may take up to 7 days.
Glucocorticoids have repeatedly shown to improve clinical scores of croup, decrease admissions, decrease return visits, decrease time in the ED and hospital and decrease the use of epinephrine in patients with croup. This is likely by decreasing the laryngotracheal edema through their anti-inflammatory actions. Dexamethasone has been the most extensively studied glucocorticoid for croup. Although other steroids may have similar effects, a majority of providers choose dexamethasone due to its multiple routes of administration, prolonged duration of action, few adverse effects and substantial evidence base.
There has been shown to be no difference between the IV, IM and oral use of dexamethasone. It is unclear if nebulized dexamethasone is efficacious, although nebulized budesonide has been shown as efficacious as IV or oral dexamethasone. Dexamethasone + budesonide was shown to be equivalent to dexamethasone alone. A lower dose of dexamethasone (0.15 mg/kg) may be similar to the more commonly used dose (0.6 mg/kg) although a majority of providers still used the higher dose.
Oral dexamethasone is foul tasting and less concentrated so many providers give the IV formulation PO for improve adherence.
There is no evidence that repeat doses of dexamethasone improve outcomes in croup.
Given that mild, moderate and severe patients with croup benefit from glucocorticoids, the Curbside pathway recommends dexamethasone for all patients presenting with symptoms of croup.
In 1978 Westley et al. developed a validated croup score to determine the severity of symptoms. Other clinical scores have been subsequently developed, but none have been validated in the clinical setting. Children with moderate to severe scores (greater than 3 on the Westley scale) will likely benefit from nebulized racemic epinephrine. Curbside uses a modified version of the Westley score (listed below) to determine the need for epinephrine.
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Nebulized racemic epinephrine causes rapid improvement in most cases of moderate to severe croup by constricting the arterioles in the upper airway causing fluid resorption and improvement of airway edema. Due to the nature of fluid dynamics, even a slight improvement in the diameter of the airway can cause large effects in the flow of air. The max effect of epinephrine appears around 20 - 30 minutes and resolves by ~120 minutes. Because of this, racemic epinephrine does not alter the natural course of croup, but simply provides symptomatic relief. There is no evidence that the patients have worsening croup scores after the epinephrine effect resolves, but simply return to their previous baseline.
Dexamethasone + nebulized epinephrine has been shown to decreased duration of hospitalization.
In several studies the evidence does not favor racemic epinephrine or L-epinephrine, or Intermittent Positive Pressure Breaths (IPPB) over simple nebulization.
Nebulized racemic epinephrine has a rapid onset of action between 5 - 10 min. By the time the nebulized treatment is complete most patients will begin to have some effect from the medication. If a patient arrives with severe signs of croup and does not improve with a nebulized dose, transfer to an ICU and evaluation of other causes of upper airway obstruction (foreign body, epiglottitis, bacterial tracheitis, etc.) should be considered.
Multiple studies have shown that croup scores return to their baseline ~120 min after nebulized epinephrine and that epinephrine does not alter the longer term progression of disease. Patients who are being discharged who have received nebulized epinephrine should be observed for at least 2 hours to ensure that their symptoms do not return.
There have been several randomized trials that have shown no effect of mist therapy in the treatment of croup. Although deliver of nebulized treatments and oxygen should be humidified, there is no role for mist therapy as a primary treatment modality.
Many different viruses may cause croup. Identification of the exact pathogen is unlikely to improve the outcomes of patients given the clinical diagnosis and clinical management of the patient. Therefore, guidelines commonly do not advocate for the use of viral or other laboratory studies in the management of croup. The exception to this may be for influenza testing for prophylaxis or for cohorting of admitted patients.
Both chest x-rays and neck x-rays are rarely useful in the diagnosis and treatment of croup. CXR may demonstrate a "steeple sign", representing the subglottic narrowing. The lateral neck view may demonstrate hypopharynx overdistention during inspiration.
X-rays may be useful to evaluate for other diagnosis that may present with airway obstruction such as foreign body aspiration or epiglottitis.
Bacterial tracheitis may mimic some of the initial symptoms of croup or present as a secondary superinfection imposed upon croup. The provider must play close attention to identify this critical disorder. Symptoms which should prompt concern for bacterial tracheitis include: high fevers, toxic appearance, and increasing respiratory distress secondary from purulent secretions. Early antibiotics, ICU admission and airway stabilization are often required for this disease process.
Epiglottitis may mimic some of the symptoms of croup and needs to be identified immediately to provide relevant care. Epiglottitis often presents with high fevers, toxic appearance, acute upper airway obstruction (tripod posture), dysphagia, drooling, and distress. The severity and drooling symptoms are less common in bacterial tracheitis, but can occur. Immediate airway intervention and antibiotics are often necessary in epiglottitis.
Spasmodic croup is similar to Laryngotracheitis however its key differentiating feature is that it ONLY occurs at night. It often occurs multiple times per night or on multiple nights for several nights in a row. Often it resolves prior to reaching care or when the child becomes less anxious. Commonly spasmodic croup requires no intervention although steroids and racemic epinephrine may improve symptoms. Spasmodic croup may have a genetic component and has been related in families with atopy.