PULMONARY EDEMA

PULMONARY EDEMA

Pulmonary edema is the accumulation of serous fluid in the alveoli and the interstitial tissue of lungs.

CAUSES

1. Increased pulmonary capillary pressure due to left ventricular failure or mitral valve disease

2. Pneumonia

3. Breathing harmful chemicals like chlorine or sulfur dioxide.

EFFECTS

Effects of pulmonary edema are severe dyspnea, cough with frothy bloodstained expectoration, cyanosis and cold extremities.

Chronic interstitial edema leads to asthma. Alveolar edema is fatal and causes sudden death due to

suffocation.

PLEURAL EFFUSION

Pleural effusion is the accumulation of large amount of fluid in the pleural cavity.

CAUSES

1. Blockage of lymphatic drainage

2. Excessive transudation of fluid from pulmonary capillaries due to increased pulmonary capillary

pressure caused by left ventricular failure

3. Inflammation of pleural membrane which damages the capillary membrane, allowing leakage of fluid

and plasma proteins into the pleural cavity.

FEATURES

Pleural effusion causes atelectasis, leading to dyspnea and other respiratory disturbances.

PULMONARY TUBERCULOSIS

Tuberculosis is the disease caused by tubercle bacilli. This disease can affect any organ in the body. However, the lungs are affected more commonly. Infected tissue is invaded by macrophages and later it becomes fibrous. Affected tissue is called tubercle.

FEATURES

Initially, alveoli in the affected part become nonfunctioning, due to thickness of respiratory membrane.

If a large part of lungs is involved, the diffusing capacity is very much reduced. In severe conditions, the

destruction of the lung tissue is followed by formation of large abscess cavities.

EMPHYSEMA

Emphysema is one of the obstructive respiratory diseases in which lung tissues are extensively damaged.

Damage of lung tissues results in loss of alveolar walls. Because of this, the elastic recoil of lungs is also lost. Emphysema is caused by:

1. Cigarette smoking

2. Exposure to oxidant gases

3. Untreated bronchitis.

DEVELOPMENT OF EMPHYSEMA

1. Smoke or oxidant gases irritate the bronchi and bron chioles, leading to chronic infection

2. It increases the mucus CAUSES

1. Blockage of lymphatic drainage

2. Excessive transudation of fluid from pulmonary capillaries due to increased pulmonary capillary

pressure caused by left ventricular failure

3. Inflammation of pleural membrane which damages the capillary membrane, allowing leakage of fluid

and plasma proteins into the pleural cavity.

FEATURES

Pleural effusion causes atelectasis, leading to dyspnea and other respiratory disturbances.

PULMONARY TUBERCULOSIS

Tuberculosis is the disease caused by tubercle bacilli. This disease can affect any organ in the body. However, the lungs are affected more commonly. Infected tissue is invaded by macrophages and later it becomes fibrous. Affected tissue is called tubercle.

FEATURES

Initially, alveoli in the affected part become nonfunctioning, due to thickness of respiratory membrane.

If a large part of lungs is involved, the diffusing capacity is very much reduced. In severe conditions, the

destruction of the lung tissue is followed by formation of large abscess cavities.

EMPHYSEMA

Emphysema is one of the obstructive respiratory diseases in which lung tissues are extensively damaged.

Damage of lung tissues results in loss of alveolar walls.

Because of this, the elastic recoil of lungs is also lost.

Emphysema is caused by:

1. Cigarette smoking

2. Exposure to oxidant gases

3. Untreated bronchitis.

DEVELOPMENT OF EMPHYSEMA

1. Smoke or oxidant gases irritate the bronchi and bronchioles, leading to chronic infection

2. It increases the mucus secretion from the respiratoryepithelial cells causing obstruction of air passage

3. Cilia of respiratory epithelial cells are partially paralyzed and the movement is very much reduced.

Because of this, the mucus cannot be removed from the respiratory passage.

4. Destruction of alveolar mucus membrane

5. Destruction of elastic tissues occur. Normally, there is loss of some elastic tissues because of

the proteolytic enzyme called elastase. But, that is very much negligible. Moreover, liver produces

elastase inhibitors especially, α1-antitrypsin, which prevents the destruction of elastic tissues.

But, due to heavy smoking or because of constant exposure to oxidant gases, the pulmonary alveolar

macrophages increase in number. Macrophages release a chemical substance, which attracts a

large number of leukocytes. Leukocytes release proteases including elastase, which destroy the

elastic tissues of the lungs.

EFFECTS OF EMPHYSEMA

1. Airway resistance increases several times due to the bronchiolar obstruction. So, the movement of

air through the respiratory passage becomes very difficult. It is more pronounced during expiration.

2. Due to the destruction of alveolar membrane and elastic tissues, the lungs become loose and floppy.

So, the diffusing capacity reduces to a great extent. However, lung compliance increases and the aeration of blood is impaired. Enough oxygen cannot diffuse into blood and carbon dioxide cannot diffuse out.

3. Obstruction also affects ventilation-perfusion ratio, resulting in poor aeration of blood

4. Due to the destruction of lung tissues, the number of pulmonary capillaries also decreases. It increases

the pulmonary vascular resistance, leading to pulmonary hypertension.

5. Over the years, chronic emphysema could lead to hypoxia and hypercapnea. It will finally cause

prolonged and severe air hunger (dyspnea), leading to death.

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