Inﬂammation of the bronchial tubes (see AIR PASSAGES; BRONCHUS; LUNGS). This may occur as an acute transient illness or as a chronic condition.
Acute bronchitis is due to an acute infection – viral or bacterial – of the bronchi. This is distinguished from PNEUMONIA by the anatomical site involved: bronchitis aﬀects the bronchi whilst pneumonia aﬀects the lung tissue. The infection causes a productive cough, and fever. Secretions within airways sometimes lead to wheezing. Sometimes the speciﬁc causative organism may be identiﬁed from the sputum. The illness is normally self-limiting but, if treatments are required, bacterial infections respond to a course of antibiotics.
Chronic bronchitis is a clinical diagnosis applied to patients with chronic cough and sputum production. For epidemiological studies it is deﬁned as ‘cough productive of sputum on most days during at least three consecutive months for not less than two consecutive years’. Chronic bronchitis is classiﬁed as a CHRONIC PULMONARY OBSTRUCTIVE DISEASE (COPD); chronic ASTHMA and EMPHYSEMA are the others.
In the past, industrial workers regularly exposed to heavily polluted air commonly developed bronchitis. The main aetiological factor is smoking; this leads to an increase in size and number of bronchial mucous glands. These are responsible for the excessive mucus production within the bronchial tree, causing a persistent productive cough. The increased number of mucous glands along with the inﬂux of inﬂammatory cells may lead to airway-narrowing: when airway-narrowing occurs, it slows the passage of air, producing breathlessness. Other less important causative factors include exposure to pollutants and dusts. Infections do not cause the disease but frequently produce exacerbations with worsening of symptoms.
Treatments involve the use of antibiotics to treat the infections that produce exacerbations of symptoms. Bronchodilators (drugs that open up the airways) help to reverse the airway-narrowing that causes the breathlessness. PHYSIOTHERAPY is of value in keeping the airways clear of MUCUS. Cessation of smoking reduces the speed of progression.