BRONCHITIS (Respiratory inflammatory disease)

Here is all about bronchitis as a respiratory inflammatory disease.

1. BRONCHITIS ~Atanu Gh0sh

2. DEFINITION Bronchitis is a pathological condition of inflammation of the mucus membrane in the bronchial tubes and cause coughing often with mucus production.

3. TYPES 1) Acute Bronchitis : Acute Bronchitis is usually caused by cold or a viral infection and goes away on its own way in a few weeks. Generally treatment is not required . 2) Chronic Bronchitis : It may be defined as a disease characterized by cough and sputum for at least 3 consecutive months in a year for more than 2 successive years (According to MRC).

4. ETIOLOGY 1) Smoking : It causes bronchoconstriction, sluggish ciliary movement, increases airway resistance, hypertrophy of the mucus glands, increases number of goblet cells and hypersecretion of mucus. 2) Atmospheric Pollution : Industrial and domestic smoke as well as Sulphur Dioxide are main causes of air pollution which are responsible for chronic bronchial irritation and increased resistance to the airflow.

5. 3) Infection : The role of infection is uncertain, but it appears that once it develops chronic irritation is maintained and progress to emphysema. The main organisms are Haemophilus influenzae, Streptococcus pneumoniae and Mycoplasma pneumoniae etc. 4) Occupation : Coal-miners and industrial workers are more often exposed to dust and fumes which may irritate the bronchial tree.

6. 5) Genetics : Familial and genetic abnormalities associated with Alpha-1 antitrypsin* deficiency may also be present. *(It is an Anti-protease enzyme and Function of this is to protect the lungs from Protease mediated tissue destruction . It is produced primarily in the liver. It inhibits the Neutrophil elastase activity in the lungs; elastase is a Serine Protease produced by Pancreas.) 6) Others : Cold also causes acute Bronchitis.

7. PATHOLOGY 1) Mucus Glands : Due chronic irritation mucus glands undergo hypertrophy which is the main pathological finding in chronic bronchitis. Reid Index = (Thickness of Mucus gland)/(Thickness of bronchial wall) Normally Reid Index is 0.28 but in Chronic Bronchitis it becomes 0.58 2) Goblet cells : In bronchioles goblet cells proliferate and are overdistended with sputum.

8. 3) Mucus : Mucus Secretion is enormously increased due to hypertrophy of mucus glands and proliferation of Goblet cells. This is the cause of chronic cough and sputum. 4) Infection : Increased mucus predisposes to infection by various organisms which leads to further diseases. e.g., H. influenzae causes Influenzae; Strep. pneumoniae causes pneumoniae.

9. 5) Airways obstruction : This is the most important functional abnormality and is caused by numbers of factors. Overproduction of mucus. Inflammatory swelling and oedema. Spasm of smooth muscle. Fibrosis. Air trapping at bronchioles. Emphysema. (In about 50% cases of chronic bronchitis, Emphysema develops. This is due to repeated infection and air trapping. Centriacinar or Panacinar emphysema may develop.)

10. Cntriacinar Emphysema : Proximal or central part of the acinus is affected but distal part is normal. Seen in smokers and coal-workers.(External Cause) Upper zones of lungs are affected most. Panacinar Emphysema : All parts of acinus are involved. Seen in patients with Alpha1-Antitrypsin deficiency.(Internal or Genetical Cause) lower zones of lungs are affected most.

11. 6) Air diffusion : Due to uneven distribution of the inspired air, there may be diminished diffusing capacity. Airway obstruction gives rise to ventilation perfusion inequality, resulting in increased PaCO2 and reduction in PaO2 and this gives rise to respiratory acidosis. 7) Pulmonary hypertension & Chronic cor pulmonale : As a result of low PaO2 pulmonary vasoconstriction takes place leading to pulmonary hypertension. There are also other undetermined factors. It occurs mostly during infection. Ultimately patient develops right ventricular failure.

12. Cor Pulmonale to Right Heart Failure :- Hypoxic Pulmonary Vasoconstriction > Increased resistance in lung > Pulmonary Hypertension > It’s hard for the right ventricle of heart to pump blood into the Pulmonary Circulation > Right Heart Failure

13. Clinical Features Symptoms : Cough with expectoration. Acute respiratory infection from time to time may give rise to fever, aggravation of cough and sputum with purulent character. Shortness of breath due to airway obstruction, bronchiolar spasm. Blue Bloaters ( it’s called due to Cyanosis). All these symptoms may be present for 10 years or more.

14. Signs : Stocky body build. Respiratory rate is hurried. Central Cyanosis may be present. Suffused conjunctivae. Raised temperature. Dilated superficial veins are present with warm periphery. Accessory respiratory muscles are prominent and patient may prefer to stoop forwards during respiratory distress. If right heart failure exists, neck veins may be full with pitting pedal edema. In late stages features of Emphysema will develop.

15. Special Investigations Blood count is usually normal or may show leukocytosis in presence of acute infection. Bacteriological culture of sputum may yield the pathogenic organisms, mostly H. influenzae, pneumococci, staphylococci, Streptococcus pneumoniae . Pulmonary function tests show reduced FEV1: FVC ratio in early stage. In severe cases FVC is markedly diminished. Lung volume measurements show increased TLC and marked increased in RV. Elevation of RV: TLC ratio indicates the air trapping. ECG may show evidence of Right ventricular hypertrophy.

16. complications Emphysema. Bronchiolar spasm. Bronchiectasis. Fibrosis of lung. Chronic cor pulmonale. Right heart failure. Hernia in different sites. Haemoptysis .

17. Treatment Smoking should be avoided. Control of air pollution. Steam inhalation or hot drink helps to liquefy the sputum which may be coughed out easily. If there is bronchospasm, Aminophylline can be given. It is a bronchodilator. Control of infection should be done very promptly by Ampicillin, Erythromycin, Ciprofloxacin, Ofloxacin etc.

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