RSV

Snapshot

• A 1-year-old toddler is brought to the emergency room for trouble breathing. His parents report that for the past few days, he has had low-grade fevers, nasal congestion, and a cough. Today, he did not appear to want to eat or drink any water. On physical exam, he is saturating 88% on room air. He has a prolonged expiratory phase and diffuse wheezes bilaterally. He has nasal flaring and intercostal retractions. He is given supplemental oxygen and admitted for further management.

Introduction

• Classification
  • respiratory syncytial virus (RSV)
    • an enveloped, linear, single-stranded, negative-sense RNA virus with a helical capsid
    • a paramyxovirus
    • causes bronchiolitis in infants and atypical pneumonia 
• Epidemiology
  • incidence
    • more common in the winter
  • demographics
    • children < 2 years of age 
  • risk factors
    • daycare centers
    • exposure to air pollutants such as cigarette smoke
    • cardiopulmonary disease
    • immunodeficiency
    • premature infants
• Pathogenesis
  • the virus contains surface protein F (fusion), which induces respiratory epithelial cells to form multinucleated giant cells
  • 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
• Prevention
  • palivizumab
    • mechanism
      • monoclonal antibody against F protein
    • indication
      • premature infants
      • babies at risk of severe infection (i.e., immunocompromised status)
• Prognosis
  • typically self-limited
• more severe in infants < 6 months of age

Presentation

• Symptoms 
  • low-grade fever
    • a high fever may indicate pneumonia
  • congestion
  • cough
  • poor feeding
  • grunting
• Physical exam
  • tachypnea
  • bilateral wheezing
  • prolonged expiratory phase
  • increased work of breath
    • nasal flaring
    • intercostal retractions
  • focal crackles
• in patients with pneumonia

Imaging

• Chest radiography  
  • indication
    • suspected pneumonia
  • findings
• diffuse patchy infiltrates

Studies

• Making the diagnosis
• most cases are clinically diagnosed

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

Treatment

• Conservative
  • supportive care
    • indication
      • all patients
    • modalities
      • hydration
      • supplemental oxygen
• superficial nasal suctioning

Complications

• Hypoxemic respiratory failure
  • treatments
    • oxygen
    • mechanical ventilation