Acute Bronchitis

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | Referral

Definition

Acute bronchitis is a self-limiting inflammation of the bronchi, usually caused by a viral infection, leading to cough and sometimes sputum production. It is distinct from chronic bronchitis and does not involve persistent airflow limitation.

Aetiology

Most cases of acute bronchitis are viral in origin:

  • Viruses:
    • Influenza virus.
    • Parainfluenza virus.
    • Respiratory syncytial virus (RSV).
    • Coronavirus.
    • Adenovirus.
    • Rhinovirus.
  • Bacterial causes (rare):
    • Mycoplasma pneumoniae.
    • Chlamydia pneumoniae.
    • Bordetella pertussis (consider in prolonged cough).

Pathophysiology

Acute bronchitis involves:

  • Viral or bacterial infection causing inflammation of the bronchial mucosa.
  • Increased mucus production, leading to cough and sputum.
  • Transient narrowing of the airways due to swelling.
  • Resolution occurs as the infection clears and inflammation subsides.

Risk factors

  • Smoking or exposure to second-hand smoke.
  • Pre-existing lung conditions (e.g., asthma, COPD).
  • Exposure to air pollution or irritants (e.g., dust, fumes).
  • Weakened immune system (e.g., recent viral illness).
  • Seasonal outbreaks (common in winter).

Signs and symptoms

Symptoms:

  • Cough (often lasting 2–3 weeks).
  • Sputum production (clear, yellow, or green).
  • Low-grade fever (occasionally).
  • Wheezing or chest tightness.
  • Fatigue or malaise.

Signs:

  • Wheezing on auscultation.
  • Rhonchi (coarse breath sounds) that clear with coughing.
  • No significant hypoxia or respiratory distress in most cases.

Investigations

Acute bronchitis is primarily a clinical diagnosis. Investigations are rarely needed unless complications or alternative diagnoses are suspected:

  • Pulse oximetry: to assess oxygen saturation in patients with respiratory symptoms.
  • Chest X-ray: indicated if pneumonia is suspected (e.g., high fever, tachypnoea, crepitations).
  • Sputum culture: consider in prolonged or severe cases to exclude bacterial infection.
  • COVID-19 or influenza testing: if indicated by local guidelines.

Management

1. Supportive Care:

  • Hydration: encourage fluid intake to thin mucus and improve clearance.
  • Antipyretics: paracetamol or ibuprofen for fever and discomfort.
  • Rest: advise patients to avoid strenuous activities.
  • Reassurance: symptoms typically resolve within 2–3 weeks without specific treatment.

2. Avoid Routine Antibiotics:

  • Antibiotics are not recommended unless there is strong evidence of bacterial infection (e.g., Bordetella pertussis).

3. Symptom Relief:

  • Cough suppressants: simple linctus or honey may help alleviate cough (avoid in children under 1 year).
  • Bronchodilators: salbutamol inhaler may be used in patients with wheezing or underlying asthma/COPD.

Referral

Refer to secondary care if any of the following are present:

  • Severe respiratory distress: increased work of breathing or hypoxia (SpO₂ <92%).
  • Suspected pneumonia: persistent high fever, tachypnoea, or focal chest signs on examination.
  • Recurrent episodes: consider underlying conditions like asthma, COPD, or pertussis.
 
RespiratorymypanotesAcute Bronchitis