WHAT IS EMPHYSEMA?
The WHO has defined pulmonary emphysema as combination of permanent dilation of air spaces distal to the terminal bronchioles and the destruction of the walls of dilated air spaces. Thus emphysema is defined morphologically whike chronic bronchitis is defined clinically . since the two conditions co exist frequently and show considerable overlap in their clinical terms, it is usual to label patients as predominant emphysema and predominant bronchitis.
According to the portion of acinus involved into 5 types:
- Para septal
WHAT ARE THE ETIOPATHOGENESIS OF EMPHYSEMA
The component form of COPD is the combination of chronic bronchitis and pulmonary emphysema. Chronic bronchitis however does not always lead to emphysema nor all the cases of emphysema have changes of chronic bronchitis. The association of two conditions is principally linked to the common etiologic factors most important is tobacco smoke and air pollutants.
However pathogenesis of the most significant event is emphysema the destruction of the alveolar walls is not linked to bronchial changes but is closely related to the deficiency of the serum alpha 1- antitrypsin commonly termed protease-antiprotease hypothesis.
Protease- antiprotease hypotheis:
Alpha 1 antitrypsin also called alpha 1 protease inhibitor is a glycoprotein that forms the normal constituent of the alpha 1 globulin fraction of the plasma protein on the serum electrophoresis. The single gen is located in the ong arm of the chromosome 15. It is normally syntheiszed in the liver and is distributed in the circulating blood. The normal function of the alpha 1 antitrypsin is to inhibit protease and hence its name alpha 1 protease inhibitor. The protease are derived from the neutrophils. Neutrophils elastase has the capability of digesting lung parenchyma but is inhibited from doing so by the anti elastase effect of the alpha 1 –AT 1.
WHAT IS PLEURA?
Visceral pleura covers the lung and extends into the fissures while parietal pleura limits the mediastinum and covers the dome of the diaphgram and ineer aspects of the chest wall. The two layers between them enclose pleural cavity which contains less than 15ml of clear serous fluid.
WHAT ARE ITS INFLAMMTIONS?
Its involvement of the pleura is commonly termed pleurities or pleurisy. Depending upon the character of resultant exuduate it can be divided into serous fibrinous and serofibrinous suprative or empysema
- Serous fibrinous and sero fibrinous: acute inflammation of the pleural sac can result in serous , serofibrious and fibrious exudate. Most of the cases of such tuberculosis, pneumonias, pulmonary infracts, lung abscess, and bronchiectasis. Other causes include a few collagen disease , uraemia , metastatic involvement of the pleura, irradiation.
Pleurisy causes pain un the chest on breathing and a friction rub is audible on auscultation.
- Suppurative pleuritis: bacterial or mycotic infection of the pleura cavity that converts a serofibrious effusion into purulent exudate is termed suppurative pleurities or empyema thoracis. The most common causes is direct spread of pyogenic infection from subdiaphragmatic abscess or liver abscess and penetrating injuries to the chest wall. Occasionally the spread may occur by haematogenous or lymphatic routes.
In empyema the exudate is yellow green creamy pus that accumulates in large volume. Empyema is eventually replaced by granulation tissue and fibrous tissue which obliterate tha cavity and with passage of years calcification may occur. The effect of these is serious respiratory difficulty due to inadequate pulmonary expansion.
3.haemorrhagic pleurities: haemorrhagic pleurities differs from haemthorax in having inflammatory cells or exfoliated tumour cells in the exudate. The causes of haemorrhagic pleuritis are metastatic involvement of the pleura bleeding disorders and rickettsial disease.
Non inflammatory pleural effusion:
THATS ALL ABOUT LEARN ABOUT EMPHYSEMA.