This is one of the common respiratory disorders seen all over the world accounting for a great deal of morbidity and mortality.
The disease is very common (1.
7-6.
2% of the population) in India, though the incidence varies in different areas.
Males are affected 5-6 times more than females.
Lower socio-economic groups are affected more.
Definition Chronic bronchitis is defined as a disease characterized by hypersecretion of mucus sufficient to cause cough and sputum on most days of at least three months in a year for two or more consecutive years.
This happens in the absence of any other specific respiratory or cardiovascular disease.
In the initial stages the inflammation of the bronchi is recurrent, it becomes constant later.
The larger air passages are affected during the early part of the disease, later obstructive features set in when the smaller airways are also affected.
Infection leads to periodic aggravation of the symptoms and the sputum, which is mucoid, becomes purulent during these episodes.
As the airways obstruction progresses, emphysema sets in.
These two processes become established in the majority of cases so that the condition is termed chronic bronchitis emphysema syndrome (CBES).
The disease is more common in damp, cold and dusty regions.
Atmospheric pollution is accompanied by a higher incidence of CBES.
1.
It is probable that genetic factors play a role in the development of chronic bronchitis.
2.
Factors such as smoke, dust, and other forms of environmental pollution lead to irritation of the respiratory tract and predispose to CBES.
3.
Cigarette and smoking is the most prominent single factor associated with CBES.
The incidence and severity are directly proportional to the average number of cigarettes or beedies smoked every day and the duration of smoking.
Smoking results in irritation of the bronchi, hypersecretion of mucus and impairment of ciliary motility.
These also predispose secondary infection.
Recurrent bronchopulmonary infections by viruses such as influenza and parainfluenza, mycoplasma or bacteria.
Such as pneumococcus and H.
influenzae, aggravate the damage to the bronchopulmonary segments and perpetuate the condition.
Immunological factors are also important in some cases.
The sputum shows high eosinophil counts in such cases.
Type I antigen antibody reaction occurs in the airways.
The immunologically-mediated reaction further damages the bronchi.
Pathology The bronchial mucosa shows hypertrophy and increase of the mucous glands and goblet cells with consequent overproduction of viscid mucus.
The distal airways show narrowing of lumen caused by increased thickness of the muscle and connective tissue.
The mucosa becomes ulcerated and when the ulcers heal, fibrosis occurs resulting in distortion of the lumen with stenosis and dilatation.
Distortion of the airways leads to permanent obstruction.
Secondary infection occurs in the later stages.
The ciliary movement is further impaired by the abnormally viscid mucus.
This aggravates infection and a vicious cycle is established.
Severe recurrent infections cause the development of microabscesse in the bronchial wall.
These heal with fibrosis.
Squamous metaplasia occurs.
Distortion and obstruction of the bronchial lumen result in air trapping and emphysema of the alveoli, some show collapse and fibrosis.
The capillary bed is distorted and truncated and this causes pulmonary arterial hypertension.
The pulmonary arteries become distended and atheromatous.
Pulmonary hypertension gives rise to right ventricular hypertrophy and dilatation.
Chronic cor pulmonale supervenes as time passes.
Clinical features The clinical picture is varied depending on the severity of pulmonary lesion and its duration.
The most frequent early symptom is cough recurring year after year, especially so in winter months.
Later the cough becomes constant.
Expectoration is mucoid and the sputum is tenacious, especially on waking up in the morning.
Many complain of a feeling of tightness of the chest.
Physical examination reveals mild wheeze which disappears as the patient clears the bronchi by expectoration.
Variable degrees of bilateral rhonchi and coarse crepitations are heard as adventitious sounds.
Initially acute infections give rise to fever and purulent sputum.
As the infection becomes established, fever and other general symptoms come down.
At this stage the quantity and character of the sputum are more reliable indicators of infection.
The sputum becomes copious in amount when bronchiectatic changes develop.
With the development of emphysema the chest assumes the inspiratory position and the respiratory excursions are considerably diminished.
At this stage dyspnea is far out of proportion to the physical findings in the chest.
Diagnosis Chronic bronchitis should be diagnosed from the history of recurrent cough extending over several years, mucopurulent sputum and the physical findings of bronchila obstruction and emphysema.
X-ray is normal in the early stages but the features of emphysema may be evident later.
Bronchography is not generally required for diagnosis in the ordinary case.
It may reveal distortion and diverticula of the major bronchi, bronchiolectasis and distortion and non-filling of the peripheral bronchi.
Lung function tests show reduction in vital capacity, increase in the closing volume and features of airway obstruction.
Differential diagnosis Chronic bronchitis has to be distinguished from bronchial asthma and emphysema.
Differentiation is easy in the early stages but there is considerable overlap of symptoms and signs in the advanced stage, and, therefore, the clinical assessment is difficult hence these three diseases-asthma, emphysema and chronic obstructive airways disease (COAD).
Other conditions like pulmonary tuberculosis, bronchietasis, left-sided heart failure and bronchogenic carcinoma have to be ruled out in atypical cases.
Course and prognosis Established chronic bronchitis is incurable.
Over several years the condition progresses to produce complications and death.
Each infective episode leads to further deterioration and precipitates and cor pulmonale.
Complications The following are the complications involved • Frequent respiratory infections • Respiratory failure and • Right sided heart failure (cor pulmonale) Management General measures: Most effective single step to prevent deterioration is to stop smoking.
This single measure itself affords considerable relief of symptoms.
Environmental allergens and pollutants must be avoided by the patient.
Other general measures include improvement in general health, regular exercise, deep-breathing exercises, adequate sleep, treatment of obesity, and eradication of foci of sepsis in the throat, nose and paranasal sinuses.
If these measures are started during the early phase of the disease, further progression can be arrested.
Drugs: Apart from the general measures, no active treatment is indicated in the early stages.
Treatment of infective episodes: A broad spectrum antibiotic should be employed for 7-10 days during an infective episode.
Tetracycline or ampicillin may be stated initially.
Depending on the microbiological tests, the antibiotic may have to be changed.
Bronchospasm has to be relieved by the use of bronchodilators such as aminophylline or Salbutamol.
If the cough is ineffective and troublesome, cough suppressants like linctus codeine are indicated.
Use of acetyl cystein or bromhexine hydrochloride 8mg thrice daily orally helps to liquefy the sputum.
Steam inhalations helps to improve vital capacity.
Steam inhalations help to improve vital capacity, relieve emphysema and open up the airways by expectorating the sputum.