Snapshot A 4-year-old boy presents to the emergency room for a cough. His mom reports that he has had this cough for about a day along with fevers, runny nose, and a hoarse voice. He started having some difficulty breathing this afternoon, so his mother brought him to the emergency room. On physical exam, he has a deep barking cough, use of accessory muscles, and inspiratory stridor. He is sent for a chest radiograph, which showed a positive steeple sign. He is immediately given nebulized epinephrine and a dose of steroids. The physician reassures the patient’s mother that this will likely resolve without any complications. Introduction Clinical definition upper respiratory infection characterized by barking cough Epidemiology incidence common demographics children < 6 years of age boys > girls Etiology parainfluenza virus (most common) paramyxovirus RNA virus influenza virus orthomyxovirus RNA virus Pathogenesis the virus causes inflammation of the upper airway edema, epithelial necrosis, and infiltration of inflammatory cells this causes narrowing of subglottic airway, resulting in stridor and increased work of breath Associated conditions bronchiolitis Prognosis most cases resolve without complications Presentation Symptoms “seal-like” deep barking cough difficulty breathing sore throat hoarseness congestion symptoms are worse at night Physical exam fever inspiratory stridor tachypnea accessory muscle use pulsus paradoxus with severe croup and upper airway obstruction Imaging Chest radiography indication all patients findings may show a steeple sign indicating subglottic narrowing Studies Making the diagnosis based on clinical presentation Differential Acute epiglottitis distinguishing factors patients typically have muffled voice, drooling, high fever, and have dysphagia a medical emergency absence of barking cough Treatment Conservative supportive care indication all patients modalities supplemental oxygen hydration Medical single dose of steroids indication all patients nebulized epinephrine indications all patients Complications Respiratory failure Pneumonia