creation date: 2026-09-08 16:34
tags: Pathologies
Bronchiolitis
Background
Definitions
Bronchiolitis is a viral lower respiratory tract infection characterized by small airway obstruction.
Etiology
Viruses responsible include:
- RSV (most cases)
- HMPV
- Influenza
- Rhinovirus
- Adenovirus
- Parainfluenza
Pathogenesis
Infection with virus results in acute inflammation, edema, and necrosis of the epithelial cells lining the small airway. This, with increased mucus production, narrows the small airways.
Risk Factors
Bronchiolitis primarily affect children in the first two years of life. Reinfections later in life are generally milder.
RSV season begins between November and January and persist for 4-5 months.
Clinical Presentation
Signs & Symptoms
Findings may range from mild URTI to impending respiratory failure.
Prodrome (3 days):
- Fever
- Cough
- Rhinorrhea
Progresses to:
- Tachypnea
- Wheeze and crackles
- Respiratory distress
Respiratory distress manifests as:
- Grunting
- Nasal flaring
- Indrawing
- Retractions or abdominal breathing
History & Physical Exam
History may include:
- History of exposure to individual with viral URTI
Physical should include:
- Vitals
- Auscultation of the lungs
Diagnosis
Criteria
Diagnosis is made clinically.
Work-up
Tests are not routine nor indicated in typical cases of bronchiolitis.
Differential
Diagnoses for wheezing in young children:
- Asthma
- Other pulmonary infections (eg. pneumonia)
- Laryngotracheomalacia
- Foreign body aspiration
- Gastroesophageal reflux
- Congestive heart failure
- Vascular ring
- Allergic reaction
- Cystic fibrosis
- Mediastinal mass
- Tracheoesophageal fistula
Red Flags / Complications
Management
Disposition
Admission may be considered based on the clinical status of the child. The illness tends to worsen over the first 72 hours which may be relevant.
Risk factors for severe disease include:
- Pre-maturity (<35 weeks gestation)
- <3 months of age at presentation
- Hemodynamically significant cardiopulmonary disease
- Immunodeficiency
Admission may be required for:
- Signs of severe respiratory distress (eg. indrawing, grunting, RR >60/min)
- Supplemental O2 required to keep saturation >90%
- Dehydration or history of poor fluid intake
- Cyanosis or history of apnea
- Infant at high risk for severe disease
- Family unable to cope
Treatment
Bronchiolitis is a self-limiting disease and most children can be managed with supportive care at home.
Admitted patients
Recommended treatment include:
- Oxygen
- Hydration
Treatments that may help include:
- Nebulized epinephrine
- Nasal suctioning
- Dexamethasone (with epinephrine)
Note that the following is not recommended:
- Salbutamol
- Corticosteroids
- Antibiotics or antivirals
- 3% hypertonic saline nebulization
- Chest physiotherapy
- Cool mist therapies