What are the differences in diagnosis and treatment between bronchiolitis and asthma?

Bronchiolitis vs Asthma: Differences in Diagnosis and Treatment

Bronchiolitis and asthma are distinct respiratory conditions with different diagnostic criteria and treatment approaches, with bronchiolitis being primarily a viral lower respiratory tract infection in infants while asthma is a chronic inflammatory disorder requiring different management strategies.

Diagnostic Differences

Bronchiolitis

• Definition: A viral lower respiratory tract infection primarily affecting infants under 24 months of age 1
• Key Clinical Features:
  • Typically begins with rhinitis and cough, progressing to tachypnea, wheezing, rales, accessory muscle use, and/or nasal flaring 1
  • Most common in infants aged 1-23 months 1
  • Seasonal pattern with highest incidence between December and March (in North America) 1
  • Respiratory syncytial virus (RSV) is the most common cause (90% of children infected in first 2 years) 1
  • Other causative viruses: human rhinovirus, human metapneumovirus, influenza, adenovirus, coronavirus, and parainfluenza 1

Asthma

• Definition: A chronic inflammatory disorder of the airways characterized by variable and recurring symptoms, airflow obstruction, bronchial hyperresponsiveness, and underlying inflammation 1
• Key Clinical Features:
  • Recurrent episodes of coughing (particularly at night/early morning), wheezing, breathlessness, and chest tightness 1
  • Associated with widespread but variable airflow obstruction that is often reversible 1
  • Often has allergic component with atopic predisposition 2
  • Can occur at any age but often begins in childhood
  • May show airway remodeling with persistent changes in airway structure including sub-basement fibrosis, mucus hypersecretion, epithelial cell injury, smooth muscle hypertrophy, and angiogenesis 1

Diagnostic Testing

• Bronchiolitis:

  • Primarily a clinical diagnosis based on history and physical examination
  • Chest radiographs are NOT routinely indicated 3
  • Viral testing is not necessary for typical presentations 3
  • Laboratory evaluation not recommended for routine cases 3

• Asthma:

  • Lung function testing (spirometry) showing reversible airflow obstruction
  • Assessment of bronchial hyperresponsiveness
  • Evaluation for allergic sensitization may be helpful
  • May require exclusion of other conditions that mimic asthma 4

Treatment Differences

Bronchiolitis Management

• Primary Approach: Supportive care 3

  • Adequate hydration
  • Nasal saline and gentle suctioning to clear secretions
  • Antipyretics for fever and discomfort
  • Supplemental oxygen only if SpO₂ <90% in previously healthy infants 3

• Medications:

  • Bronchodilators: NOT recommended for routine use in bronchiolitis 3
  • Corticosteroids: NOT recommended for routine management 3
  • Antibiotics: Should be avoided unless specific evidence of bacterial co-infection 3

Asthma Management

• Primary Approach: Control underlying inflammation and relieve bronchoconstriction

  • Step-wise approach to medication management
  • Identification and avoidance of triggers

• Medications:

  • Short-acting beta-agonists (SABAs): First-line therapy for quick relief of symptoms 1
  • Inhaled corticosteroids (ICS): Cornerstone of long-term control therapy 1
  • Long-acting beta-agonists (LABAs): Used in combination with ICS for persistent asthma
  • Leukotriene modifiers, anticholinergics, and biologics for specific phenotypes

Important Clinical Distinctions

1. Age Consideration:

   • Bronchiolitis primarily affects infants under 24 months 1
   • Asthma can affect all age groups but often begins in childhood

2. Disease Course:

   • Bronchiolitis: Typically an acute, self-limited illness
   • Asthma: Chronic condition with recurrent episodes requiring ongoing management

3. Viral Etiology Significance:

   • RSV bronchiolitis: Associated with younger age, mechanical obstruction due to mucus/cell debris, increased risk of recurrent wheezing 2
   • Rhinovirus-induced wheezing: Associated with atopic predisposition and higher risk of subsequent asthma development 2

4. Relationship Between Conditions:

   • Infants with bronchiolitis have increased risk of subsequent wheezing and possible asthma development 5
   • The direction of causality remains uncertain—bronchiolitis may either lead to asthma or represent the first clinical presentation of asthma predisposition 5

Management Algorithms

For Bronchiolitis:

1. Assess severity based on respiratory rate, work of breathing, and oxygen saturation
2. Provide supportive care (hydration, nasal suctioning)
3. Monitor oxygen saturation; provide supplemental oxygen if SpO₂ <90%
4. Escalate to high-flow nasal cannula if respiratory distress worsens
5. Avoid routine use of bronchodilators, corticosteroids, and antibiotics
6. Consider discharge when oxygen saturation is ≥90% on room air, adequate oral intake is established, and respiratory distress has significantly improved 3

For Asthma:

1. Assess severity based on symptoms, lung function, and response to therapy
2. For acute exacerbations:
   • Provide oxygen for hypoxemia
   • Administer repetitive or continuous SABAs
   • Give oral systemic corticosteroids
   • Consider adjunctive treatments for severe cases
3. For long-term management:
   • Implement step-wise approach to medication
   • Provide education on trigger avoidance
   • Develop written asthma action plan
   • Schedule regular follow-up to assess control 1

Common Pitfalls to Avoid

1. Misdiagnosis: Vocal cord dysfunction, respiratory bronchiolitis interstitial lung disease, and bronchiectasis can mimic asthma 4

2. Overtreatment of Bronchiolitis: Avoid unnecessary medications that have not shown benefit (bronchodilators, corticosteroids) 3

3. Undertreatment of Asthma: Failing to address underlying inflammation can lead to poor control and increased exacerbations

4. Failure to Recognize Transition: Not identifying when recurrent post-bronchiolitis wheezing has evolved into asthma

5. Inappropriate Antibiotic Use: Antibiotics should be reserved for specific bacterial infections, not viral respiratory illnesses 3