Bronchitis Inflammation of the Bronchial Tubes

John Diver^1*, James Peter¹, Catherine Brown²

¹Division of Molecular and Clinical Medicine, School of Medicine, University of Dundee, United Kingdom

²Department of Respiratory Sciences, Institute for Lung Health, United Kingdom

*Corresponding Author: John Diver, Division of Molecular and Clinical Medicine, School of Medicine, University of Dundee, United Kingdom, E-mail: diver@john.uk

Abstract

Bronchitis is a respiratory condition characterized by inflammation of the bronchial tubes, leading to coughing, mucus production, and breathing difficulties. It is broadly categorized into acute and chronic forms, each with distinct etiologies, clinical courses, and management strategies. Acute bronchitis is typically caused by viral infections and is self-limiting, whereas chronic bronchitis, often associated with chronic obstructive pulmonary disease (COPD), is caused by long-term exposure to irritants such as tobacco smoke. This article provides an overview of the pathophysiology, risk factors, clinical features, diagnostic approaches, treatment modalities, and preventive measures for bronchitis, aiming to highlight its public health significance and the need for awareness and early intervention.

Keywords: Bronchitis; Acute bronchitis; Chronic bronchitis; Respiratory inflammation; COPD; Cough; Viral infection

Introduction

Bronchitis is a common inflammatory disease of the lower respiratory tract, specifically involving the bronchial tubes that carry air to and from the lungs [1]. It presents with hallmark symptoms such as a persistent cough, sputum production, chest discomfort, and, occasionally, shortness of breath. Bronchitis can be either acute or chronic, depending on its duration and underlying cause.

Acute bronchitis is usually a short-term illness that arises from viral infections and typically resolves within a few weeks. Chronic bronchitis, on the other hand, is a long-standing condition defined by a productive cough lasting at least three months in two consecutive years. It is a major component of chronic obstructive pulmonary disease (COPD), a leading cause of morbidity and mortality worldwide.

Understanding the pathophysiology and management of bronchitis is essential for both healthcare professionals and the general public, given its prevalence and impact on quality of life[2].

Types and Causes of Bronchitis

Acute Bronchitis

Acute bronchitis is most often triggered by viral infections such as influenza, rhinovirus, respiratory syncytial virus (RSV), and coronavirus. Less commonly, it may be caused by bacterial pathogens like Mycoplasma pneumoniae or Bordetella pertussis. Environmental irritants, such as air pollutants or chemical fumes, can also provoke acute bronchitis in susceptible individuals.

The inflammation in acute bronchitis leads to increased mucus secretion, reduced ciliary function, and temporary airway obstruction, which results in the characteristic cough and sputum production.

Chronic Bronchitis

Chronic bronchitis is primarily caused by prolonged exposure to inhaled irritants, most notably cigarette smoke. Other risk factors include air pollution[3], occupational exposures (e.g., coal dust, silica), and recurrent respiratory infections. Chronic bronchitis is defined clinically by a productive cough on most days for at least three months per year for two consecutive years.

In chronic bronchitis, the bronchi are persistently inflamed, leading to thickening of the airway walls, hyperplasia of mucus-secreting glands, and decreased airway clearance. This chronic inflammation contributes to the airflow limitation characteristic of COPD.

Risk Factors

The risk factors for bronchitis vary depending on its type:

Smoking (primary and secondhand): Strongest risk factor for chronic bronchitis[4]

Air pollution: Urban living and exposure to vehicle emissions

Occupational exposure: Dust, fumes, and chemicals

Weakened immune system: Due to age, chronic illness, or immunosuppressive drugs

History of allergies or asthma

Frequent viral respiratory infections, especially in children

Clinical Features

Acute Bronchitis

Sudden onset of persistent cough, often starting dry and becoming productive

Clear or yellowish sputum; green sputum is not necessarily indicative of bacterial infection

Mild fever, fatigue, and chest discomfort

Wheezing or mild shortness of breath

Symptoms typically resolve in 1–3 weeks

Chronic Bronchitis

Daily productive cough lasting for months or years

Thick, excessive mucus

Breathlessness[5], especially with exertion

Wheezing and fatigue

May be accompanied by frequent respiratory infections

Often coexists with emphysema in patients with COPD

Diagnosis

Diagnosis of bronchitis is largely clinical, based on history and physical examination. The key features are cough and sputum production.

For Acute Bronchitis:

Chest auscultation may reveal wheezing or rhonchi, but lung sounds are often normal.

Chest X-rays are generally not required unless pneumonia is suspected (e.g., high fever, abnormal lung sounds, prolonged symptoms).

Pulse oximetry may be used to assess oxygen saturation.

For Chronic Bronchitis:

Spirometry is essential to assess airflow limitation and confirm a diagnosis of COPD.

Chest imaging may help exclude other causes like lung cancer or bronchiectasis.

Sputum analysis may be done during exacerbations to guide antibiotic use.

Prevention

Prevention strategies focus on reducing exposure to irritants and promoting lung health:

Avoid smoking and secondhand smoke exposure

Use protective equipment in occupational settings

Improve indoor air quality with proper ventilation

Receive annual flu shots and pneumococcal vaccines

Hand hygiene to reduce viral infections

Manage underlying conditions such as asthma and allergies

Public health campaigns to reduce smoking rates and improve air quality have been instrumental in lowering the incidence of chronic bronchitis in many countries.

Complications

If untreated or poorly managed, bronchitis can lead to several complications:

Pneumonia, especially in elderly or immunocompromised individuals

Progression to COPD in chronic cases

Respiratory failure in severe, prolonged exacerbations

Frequent hospitalizations, impacting quality of life and healthcare resources

Conclusion

Bronchitis remains a significant cause of respiratory illness worldwide. While acute bronchitis is usually self-limiting and benign, chronic bronchitis is a serious condition that can impair respiratory function and lead to long-term health issues. Early recognition, appropriate management, and preventive strategies are essential to reducing the burden of bronchitis. Efforts to control risk factors—particularly smoking and air pollution—combined with public health education and access to healthcare, are critical for improving outcomes and preventing complications associated with this common respiratory condition.

Refernces

1. Albert RH (2010) Diagnosis and treatment of acute bronchitis. American Family Physician 82: 1345–1350.

2. (2024) Global Initiative for Chronic Obstructive Lung Disease (GOLD) Global Strategy for the Diagnosis, Management, and Prevention of COPD.

3. Smith SM, Fahey T, Smucny J (2017) Antibiotics for acute bronchitis. Cochrane Database of Systematic Reviews 6.

4. Seemungal TAR, Donaldson GC, Paul EA (1998) Effect of exacerbation on quality of life in patients with chronic obstructive pulmonary disease. American Journal of Respiratory and Critical Care Medicine 157: 1418–1422.

5. MacNee W (2005) Pathogenesis of chronic obstructive pulmonary disease. Proceedings of the American Thoracic Society 2: 258–266.