Chronic Obstructive Pulmonary Disease

COPD is defined as a disease state with airflow limitation that is not fully reversible.

COPD include: emphysema; destruction and enlargement of alveoli, chronic bronchitis; a clinical condition with chronic cough and phlegm, small airway disease; narrowing of the small bronchioles.

Diseases without chronic obstruction are not included within the COPD. Ex:Chronic bronchitis without chronic airway obstruction is not included.

COPD is caused by long term exposure with toxic substances and gases. Smoking is the cause for over 90% in developed countries. However, only 10-20% of heavy smokers develop COPD.

The most consistent pathological finding in COPD is increased number of mucus secreting goblet cells in the bronchil mucosa, especially in the larger bronchi. In more severe cases the bronchi are inflamed and filled with pus.

Microscopically there is acute and chronic inflammatory infiltration in the walls of bronchi and bronchioles. Lymphoid follicles may develop in severe cases. In contrast to asthma, the lymphocytic infiltrate is predominantly CD8+. The epithelium become ulcerated and squamous epithelium replaces the columnar cells. Scarring and thickening of the walls after the inflammation cause narrowing of the small airways.

The initial inflammation is considered as improvement of airway function, if smoking is stopped early. In later stages inflammation continuous even if smoking is stopped.

In later stages of the airways disease leads to progressive squamous cell metaplasia, and fibrosis of the bronchial walls. These consecutive changes are the physiological development of airflow limitation. If the airway narrowing is combined with emphysema the resulting airflow limitation is even more severe.

Read About Emphysema× Emphysema

Emphysema is irreversible enlargement of the airspaces with destruction their walls without obvious fibrosis. Emphysema is one of the diseases known collectively as chronic obstructive pulmonary disaese (COPD). Emphysema has four types based on anatomic distribution in the lobule.

Centriacinar emphysema is the most common form, more than 95% of clinical cases.

Centriacinar (Centrilobular) Emphysema In this type of emphysema the central or proximal parts of acini are affected while distal alveoli are spared. Both affected and non-affected are in the same region. The lesions are more common and more severe in the upper lobes, especially in the apical segments. Inflammation is common around brochi and bronchioles. If the centriacinar emphysema is very heavy, the distal parts of acini may be involved, making differentiation from panacinar emphysema difficult. Centriacinar emphysema occurs predominantly in heavy smokers, often in association with chronic bronchitis (COPD).

Panacinar (Panlobular) Emphysema In this type, the acini are uniformly enlarged from the level of the respiratory bronchiole to the terminal blind alveoli. The prefix “pan” refers to the entire acinus, not the entire lung. In contrast to centriacinar emphysema, panacinar emphysema tends to occur more commonly in the lower zones and in the anterior margins of the lung, and it is usually most severe at the bases. This type of emphysema is associated with α1-antitrypsin deficiency.

A, Centriacinar emphysema. Central areas show marked emphysematous damage (E), surrounded by relatively spared alveolar spaces. B, Panacinar emphysema involving the entire pulmonary lobule.

Distal Acinar (Paraseptal) Emphysema Proximal parts [...]