Snapshot A 6-month old infant is seen in the emergency room for wheezing. His breathing has become increasingly difficult over the past 2-3 days. He has also had a worsening cough, subjective fevers, and rhinitis. Today, his parents took him to the pediatrician’s office, where his oxygen saturation was 80% on room air. He was sent immediately from the clinic to the emergency room via ambulance, where he was given supplemental oxygen. On physical exam, he has increased work of breath with nasal flaring, grunting, and intercostal retractions. He also has bilateral wheezes. His parents are counseled on the possibility of further interventions if his oxygen saturation does not improve. Introduction Clinical definition a viral respiratory infection that causes wheezing and increased respiratory effort in children and infants Prevention palivizumab mechanism monoclonal antibody against F protein, a key protein that RSV utilizes to infect patients indication premature infants babies at risk of severe infection (i.e., immunocompromised status) Epidemiology Incidence more common in the winter Demographics children < 2 years of age Risk factors asthma day care centers exposure to air pollutants such as cigarette smoke cardiopulmonary disease immunodeficiency congenital heart disease premature infants Etiology Respiratory syncytial virus (RSV) most common an enveloped, linear, single-stranded, negative-sense paramyxovirus with a helical capsid Rhinovirus Parainfluenza virus Influenza virus Coronavirus Pathogenesis the virus initially infects the upper respiratory tract and travels to the lower respiratory tract within a few days edema of submucosa causes an obstructive pathology in the lungs, causing wheezing and respiratory distress Presentation Symptoms low-grade fever congestion cough poor feeding grunting Physical exam tachypnea bilateral wheezing prolonged expiratory phase increased work of breath nasal flaring intercostal retractions Studies Labs rapid antigen test Differential Asthma distinguishing factors typically recurrent episodes with identifiable triggers history of atopy in the patient or family Foreign body aspiration distinguishing factor unilateral wheezing DIAGNOSIS Making the diagnosis most cases are clinically diagnosed Treatment Conservative supportive care indication all patients modalities hydration supplemental oxygen Complications Hypoxemic respiratory failure treatments oxygen mechanical ventilation Prognosis Typically self-limited More severe in infants < 6 months of age