What is the best description of bronchiolitis?

Best Description of Bronchiolitis

Bronchiolitis is a disorder most commonly caused in infants by viral lower respiratory tract infection, characterized by acute inflammation, edema, and necrosis of epithelial cells lining small airways, increased mucus production, and bronchospasm, with typical signs and symptoms including rhinitis, tachypnea, wheezing, cough, crackles, use of accessory muscles, and/or nasal flaring. 1

Epidemiology and Etiology

• Bronchiolitis is the most common lower respiratory infection in infants and young children, primarily affecting children from 1 month to 2 years of age 1
• Respiratory syncytial virus (RSV) is the most common viral cause, with highest incidence occurring between December and March in North America 1, 2
• Approximately 90% of children are infected with RSV in the first 2 years of life, and up to 40% will experience lower respiratory tract infection during their initial infection 1, 2
• Other viruses that cause bronchiolitis include human metapneumovirus, influenza, adenovirus, coronavirus, and parainfluenza viruses 1, 2, 3
• RSV infection leads to more than 90,000 hospitalizations annually in the United States 1, 4
• Mortality from RSV has decreased significantly over time, from approximately 4,500 deaths annually in 1985 to around 390 deaths in 1999 1, 2

Pathophysiology

• The disease involves acute inflammation of the small airways (bronchioles) 1
• Pathological changes include edema of airway walls, necrosis of epithelial cells lining the small airways 1
• Increased mucus production contributes to airway obstruction 1
• Bronchospasm further narrows the airways 1
• These changes lead to air trapping, atelectasis, and ventilation-perfusion mismatch 4

Clinical Presentation

• Initial symptoms typically begin with rhinitis and cough, which may progress to lower respiratory tract symptoms 1, 4
• Key clinical findings include:
  • Tachypnea (increased respiratory rate) 1
  • Wheezing on auscultation 1
  • Crackles/rales on auscultation 1
  • Use of accessory respiratory muscles 1, 2
  • Nasal flaring 1, 2
  • Difficulty feeding 5
• Symptoms typically appear after an incubation period of four to six days 5
• Severe disease is characterized by persistently increased respiratory effort, apnea, or the need for intravenous hydration, supplemental oxygen, or mechanical ventilation 1

Diagnosis

• Bronchiolitis remains primarily a clinical diagnosis based on history and physical examination 1, 4
• Routine laboratory and radiologic studies are not recommended for diagnosis 1, 5
• Risk factors for severe disease that should be assessed include age less than 12 weeks, history of prematurity, underlying cardiopulmonary disease, or immunodeficiency 1

Management

• Treatment is mainly supportive, focusing on:
  • Maintaining adequate oxygenation (oxygen saturation >90%) 1, 5
  • Ensuring adequate hydration through oral, nasogastric, or intravenous routes 5, 6
  • Gentle suctioning of nasal secretions if needed 6
• Pharmacologic interventions including bronchodilators, epinephrine, corticosteroids, hypertonic saline, and antibiotics are generally not recommended for routine use 4, 5, 7

Prevention

• Palivizumab (a monoclonal antibody) is recommended for prophylaxis in high-risk infants, including those born before 29 weeks' gestation, those with chronic lung disease of prematurity, and those with hemodynamically significant heart disease 1, 4
• Standard infection prevention measures such as hand hygiene and avoiding contact with sick individuals are important 5

Long-term Outcomes

• Children hospitalized with bronchiolitis are more likely to have respiratory problems as older children, especially recurrent wheezing 1
• It remains unclear whether severe viral illness early in life predisposes children to develop recurrent wheezing or if infants who experience severe bronchiolitis have an underlying predisposition to recurrent wheezing 1, 3