Chronic Bronchitis
Chronic bronchitis could be defined as a disorder characterized by cough and sputum for at least 3 consecutive months per year for at least 2 successive years. In this state there is chronic obstruction to the alveolar inflow of air due to chronic bronchitis or bronchial asthma.
Infection
Increased mucus predisposes to infection by several organisms, e.g., viruses and germs. The primary bacteria are H. influenzae and Strep. pneumoniae. This contributes to acute inflammation of the bronchial tract leading to mucopurulent sputum, additional airway obstruction and inherent reaction. H. influenzae may persist in the sputum and could lead to fibrosis and scarring of the remote alveoli or sometimes emphysema. Airway obstruction
This is the most significant functional abnormality and is brought on by numbers of variables, e.g., overproduction of mucus, inflammatory swelling and oedema, spasm of smooth muscle, fibrosis, air trapping at bronchioles and emphysema. In the earlier part of this disease intermittent and afterwards on permanent obstruction grows.
Mucus
Mucus secretion is enormously increased as a result of hypertrophy of mucous membranes and regeneration of Goblet cells. This is the reason for chronic cough and sputum. Secretion of mucous membranes mainly contributes to the sputum volume, while that of Goblet cell is responsible for airway obstruction. Thus you will find wheeze, rhonchi and breathlessness. This mucus is chemically altered because its fucose and sialic acid concentration is raised.
Causes
Infection
The function of disease is unclear, but it seems that when it develops chronic irritation is preserved and progresses to emphysema. The primary organisms are Haemophilus influenzae and Streptococcus pneumoniae. Mycoplasma pneumonae might also be involved.
Occupation
Coal-miners and industrial workers are often exposed to dust and fumes that may irritate the bronchial tract.
Smoking
Smoking triggers bronchoconstriction, slow ciliary motion, increases airway resistance, hypertrophy of the mucous membranes, increased number of goblet cells and hypersecretion of mucus. Though smoking is supposedly the most significant cause, yet only 10%-15percent of those smokers develop COPD. Usually a cigarette smoking history of greater than 20 package Years is linked to the disease. (1 pack year is equal to smoking 20 cigarettes per day for 1 year.)
Atmospheric contamination
Industrial and domestic smoke in addition to sulphur dioxide are main causes of air pollution that are responsible for chronic bronchial irritation and increased resistance to the airflow.
Familial and hereditary abnormalities related to Alpha-antiprotease deficiency may also be present.
Types of chronic bronchitis
- Simple chronic bronchitis. Here sputum is mucoid.
- Chronic recurrent mucopurulent bronchitis. There is mucopurulent sputum present in lack of localised suppurative disease.
- Chronic obstructive bronchitis. Airway obstruction is dominant.
- Chronic asthmatic bronchitis. There is long continued cough and sputum with late onset of wheeze.
Pathogenesis, Pathology and Functional abnormality Mucous glands due to chronic irritation, mucous glands undergo hypertrophy that’s the key pathological finding in chronic bronchitis.
