Bronchitis

Inflammation of the bronchial airways, presenting acutely or chronically depending on etiology and duration.

Classified into two distinct clinical entities:

• Acute bronchitis: self-limiting inflammation of the large airways, typically viral (>90%: rhinovirus, influenza, RSV, coronavirus, adenovirus, parainfluenza), lasting <3 weeks; may follow URTI

• Chronic bronchitis: defined as productive cough for ≥3 months in 2 consecutive years, a clinical component of COPD, driven by chronic irritant exposure (smoking predominant cause) causing mucous gland hyperplasia and airway remodeling; managed as part of the COPD spectrum

This entry focuses on acute bronchitis.

• Acute cough (productive or non-productive), duration typically 1–3 weeks, may persist up to 6–8 weeks in a subset (post-infectious cough, related to transient airway hyperresponsiveness)

• Preceding or concurrent URTI symptoms: coryza, sore throat, low-grade fever

• Sputum: clear, mucoid, or purulent; purulent sputum does NOT indicate bacterial infection; reflects sloughed epithelial cells and inflammatory cells, not necessarily bacterial colonization

• Chest discomfort/soreness from coughing, mild dyspnea on exertion (uncommon)

• Wheeze may be present transiently due to bronchial hyperreactivity

• Systemic symptoms usually mild: low-grade fever, malaise

• Examination: usually normal or scattered rhonchi/wheeze that clears with coughing; no focal crackles, no signs of consolidation (these suggest pneumonia, not bronchitis)

• Red flags suggesting pneumonia instead: high fever (>38.5°C), tachypnea, tachycardia, focal chest signs (crackles, dullness, reduced air entry), hypoxia, pleuritic chest pain, general malaise/rigors out of proportion to URTI

Clinical diagnosis based on history and examination; investigations mainly to exclude pneumonia or other differentials.

• Chest X-ray: NOT routinely indicated; obtain only if pneumonia suspected; abnormal vital signs (HR >100, RR >24, temp >38°C), focal chest exam findings, or elderly/immunocompromised with systemic illness

• Pulse oximetry if respiratory distress or comorbid lung disease

• Sputum culture: not routinely useful (poor correlation with etiology, high contamination rate)

• Consider influenza/COVID/RSV testing during relevant seasonal outbreaks if it will change management (antiviral eligibility, isolation)

• Spirometry/PEFR: consider if recurrent episodes to exclude underlying asthma

Differentials: pneumonia (focal signs, hypoxia, systemic toxicity; CXR differentiates), asthma/reactive airway disease, pertussis (paroxysmal cough with whoop, post-tussive vomiting, prolonged course >2 weeks; consider in unvaccinated/incompletely vaccinated or during outbreaks), GERD-related cough, ACE-inhibitor cough (medication history), post-nasal drip/allergic rhinitis, early heart failure ("cardiac asthma" ; orthopnea, PND, bibasal crackles), COPD exacerbation (if underlying COPD), foreign body (unilateral wheeze, sudden onset, esp. children).

• Antibiotics NOT indicated in the vast majority of cases; overwhelming viral etiology; antibiotic use does not shorten duration or reduce complications and drives resistance. Exception: confirmed/suspected pertussis (azithromycin 500mg day 1 then 250mg od days 2–5), or high-risk patients with suspected secondary bacterial infection (rare)

• Symptomatic treatment (mainstay):

• Antipyretics/analgesics: paracetamol 1g PO qds prn, or NSAIDs (ibuprofen 400mg tds prn) for fever/chest discomfort

• Cough suppressants: dextromethorphan for dry, disruptive cough (evidence modest); avoid in productive cough if suppressing needed clearance

• Honey (age >1 year): evidence supports modest reduction in cough frequency/severity, first-line in mild cases especially in children

• Adequate hydration

• Avoid routine use of mucolytics, antihistamines, decongestants; limited evidence in acute bronchitis specifically

• Bronchodilators (salbutamol inhaler/nebulizer): consider only if wheeze present or underlying reactive airway disease/asthma; not routine for uncomplicated bronchitis without wheeze

• Smoking cessation counseling (reduces recurrence, prevents progression to chronic bronchitis/COPD)

• Patient education: expected course (cough may persist 2–3 weeks, up to 6–8 weeks in some), self-limiting nature, when to seek review (worsening fever, dyspnea, hemoptysis, symptoms >3 weeks without improvement)

Follow-up/escalation: reassess if symptoms worsen or fail to improve by 3 week; consider CXR, reconsider differentials (pertussis, asthma, GERD, underlying malignancy if smoker with persistent cough), refer to pulmonology if recurrent or persistent beyond expected course.