Bronchiolitis Diagnosis and Management

Definition and Pathophysiology

Bronchiolitis is a disorder most commonly caused by viral lower respiratory tract infection in infants, characterized by acute inflammation, edema, and necrosis of epithelial cells lining small airways, increased mucus production, and bronchospasm 1, 2
It involves inflammation, fibrosis, and architectural distortion of the small airways (bronchioles), which are less than 2 mm in diameter and do not contain cartilage or mucous glands 3

Most common in infants under 2 years of age, with respiratory syncytial virus (RSV) being the predominant cause in 90% of cases 1
Other viral causes include human metapneumovirus, influenza, adenovirus, and parainfluenza 1

In infants: rhinitis, tachypnea, wheezing, cough, crackles, use of accessory muscles, and/or nasal flaring 1
Typically begins with viral upper respiratory prodrome followed by increased respiratory distress 4
In adults: cough and incompletely or nonreversible airflow limitation 5, 3

In children: primarily a clinical diagnosis based on history and physical examination; laboratory and radiologic studies are not routinely recommended 4, 6
In adults: requires comprehensive medical history, physical examination, physiologic testing (spirometry with and without bronchodilator, lung volumes, and gas exchange), and radiographic studies 5, 3
High-resolution CT (HRCT) may show direct signs of abnormal bronchioles including dilation or airway wall thickening, nodular branching, and "tree-in-bud" abnormalities 5, 7

For infants: primarily supportive care including adequate oxygenation and hydration 8
Bronchodilators, corticosteroids, and antibiotics are not routinely recommended for bronchiolitis in children 8
For adults: treatment should be tailored to the specific cause or diagnosis 3
For infectious bacterial bronchiolitis, prolonged antibiotic therapy is recommended 3

The American Thoracic Society notes that bronchiolitis affects the small airways (bronchioles) that are less than 2mm in diameter 5
The American Academy of Pediatrics recommends that bronchiolitis in children is predominantly affects infants and young children under 2 years 1, 2
The American College of Chest Physicians states that chronic bronchitis is defined as productive cough lasting at least three months in two consecutive years 7

The American Academy of Pediatrics advises that in children with bronchiolitis, avoid unnecessary interventions like routine use of bronchodilators, corticosteroids, or antibiotics 8
The American Thoracic Society recommends that in adults with suspected bronchiolitis, a thorough diagnostic workup is warranted to identify the specific etiology 5, 3