Derived from the Greek words bronchion, meaning “small airway,” and -itis, meaning “inflammation.” The term refers to inflammation of the bronchioles, commonly seen in children, particularly infants.
AKA
Pediatric small airway inflammation
What is it?
Pediatric bronchiolitis is a clinical condition characterized by inflammation and obstruction of the bronchioles, most commonly caused by viral infections. It predominantly affects children under two years of age and is a leading cause of hospitalization in infants.
Caused by:
Most common causes:
Viral infections:
Respiratory syncytial virus (RSV) (most common)
Human metapneumovirus
Influenza virus
Parainfluenza virus
Rhinovirus
Less common causes:
Infection:
Bacterial superinfection in rare cases
Inflammation:
Chronic exposure to environmental irritants (e.g., tobacco smoke)
Immune:
Severe Combined Immunodeficiency (SCID) or other immune deficiencies
Other:
Post-infectious bronchiolitis
Congenital airway anomalies
Resulting in:
Airway obstruction due to mucus plugging and edema
Air trapping and impaired oxygen exchange
Increased work of breathing and hypoxemia
Structural Changes:
Edema and inflammation of bronchiolar walls
Mucus plugging and peribronchiolar inflammatory infiltrates
Atelectasis or hyperinflation in severe cases
Pathophysiology:
Viral infection initiates inflammation and edema in the bronchiolar epithelium, resulting in obstruction. Mucus production and sloughing of epithelial cells exacerbate airway narrowing, leading to air trapping, atelectasis, and ventilation-perfusion mismatch.
Pathology:
Peribronchiolar lymphocytic infiltration
Necrosis of bronchiolar epithelium
Luminal mucus plugging
Diagnosis
Clinical:
Symptoms include:
Nasal congestion and rhinorrhea
Wheezing and crackles on auscultation
Tachypnea and increased work of breathing
Hypoxemia and cyanosis in severe cases
History of recent upper respiratory tract infection
Radiology:
CXR:
Hyperinflation with flattening of the diaphragms
Patchy atelectasis and peribronchial thickening
CT of the Chest:
Rarely indicated in pediatric cases
Labs:
Viral antigen testing (e.g., RSV testing)
Arterial blood gas (ABG) analysis in severe cases
Management:
Supportive care:
Oxygen therapy for hypoxemia
Hydration and nutritional support
Monitoring for apnea in infants
Medications:
Bronchodilators for selected cases (variable efficacy)
Antiviral therapy (e.g., palivizumab prophylaxis for high-risk infants)
Avoid:
Routine use of corticosteroids and antibiotics unless indicated
Radiology Detail
CXR
Findings:
Hyperinflation and peribronchial cuffing
Patchy atelectasis
Associated Findings:
Subtle interstitial markings
Other relevant Imaging Modalities
MRI/PET CT/NM/US/Angio:
Not commonly used in pediatric bronchiolitis
Pulmonary Function Tests (PFTs):
Typically not feasible in infants but may show airflow obstruction in older children
Recommendations:
Emphasize supportive care as the mainstay of treatment
Consider hospitalization for infants with severe respiratory distress, hypoxemia, or dehydration
Key Points and Pearls:
Pediatric bronchiolitis is most commonly caused by RSV and affects children under two years of age.
Supportive care is the cornerstone of management, with oxygen therapy being critical in hypoxemic patients.
Preventive strategies, such as palivizumab for high-risk infants, can reduce hospitalization rates.
Radiologic findings include hyperinflation and peribronchial thickening, but imaging is not always necessary for diagnosis.**
