Snapshot A 5-year-old girl is brought to urgent care for difficulty breathing. For the past few days, she has had low-grade fevers, a runny nose, and a slight cough. On physical exam, she has a seal-like barking cough and audible inspiratory stridor. There is accessory muscle use with breathing. Her lung exam was normal without any wheezes. She is given the appropriate treatments for this condition, and the physician informs the family that this is likely viral and common in children. 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) a 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 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 Differential Acute epiglottitis distinguishing factors patients typically have muffled voice, drooling, high fever, and have dysphagia a medical emergency absence of barking cough Tracheal and subglottic stenosis distinguishing factors can be congenital or from prolonged intubation in critically ill patients inspiratory stridor hoarse voice absence of systemic symptoms including fever DIAGNOSIS Making the diagnosis based on clinical presentation Treatment Conservative supportive care indication all patients modalities supplemental oxygen hydration Medical single dose of steroids indication all patients nebulized epinephrine indications moderate-severe croup cool mist indications mild-moderate croup Complications Respiratory failure Pneumonia Prognosis Most cases resolve without complications