Obstructive pulmonary diseases - emphysema

Types of Obstructive pulmonary diseases (4)

1. Emphysema

2. Chronic bronchitis

3. Asthma

4. Bronchiectasis

Emphysema Distinct features (4)

1. Chronic injury (Smoking)

2. Alveolar wall destruction

3. Overinflation

4. Functional obstruction

Chronic bronchitis Distinct features (4)

1. Chronic injury (Smoking)

2. Productive cough

3. Airway inflammation

4. Physical obstruction

Asthma distinct features (2)

1. Bronchial hyperresponsiveness triggered by allergens, infections, etc.

2. Reversible obstruction

Chronic obstructive pulmonary disease (COPD) is composed of (2)

1. Emphysema

2. Chronic bronchitis

A key feature of obstructive pulmonary diseases is:

Decrease in FEV1/ FVC ratio

A key feature of restrictive pulmonary diseases is:

Near normal FEV1/ FVC ratio

Restrictive summary (4)

1. Reduced lung expansion

2. FVC Reduced

3. FEV1 Reduced

4. FEV1/ FVC Normal

Obstructive summary

1. Expiratory obstruction

2. FVC Normal or slightly reduced

3. FEV1 Reduced

4. FEV1/ FVC Reduced

Emphysema is characterized by

Characterized by permanent enlargement of the air spaces distal to the terminal bronchioles, accompanied by destruction of their walls without significant fibrosis.

Normal “Maintenance” of Alveolar Wall and ECM (4)

1. Inhaled particulate material gets into alveoli

2. Alveolar macrophage phagocytose the particles and secrete cytokines, ROS, and proteases (Elastase)

3. Proteases can damage the alveolar wall and ECM

4. Body produces antiproteases like Alpha 1 antitrypsin to keep damage in check

Pathogenesis of emphysema (2)

1. Smoking, other toxins

2. Congenital Alpha 1-antitrypsin deficiency

Consequences of emphysema

1. ECM degradation (elastin and collagen!) and alveolar wall destruction

2. Reduces surface area or gas exchange

Consequences of loss of elastin and collagen with emphysema During inhalation (2)

1. Relatively easy to breathe in

2. Airway is open

Consequences of loss of elastin and collagen with emphysema During exhalation (4)

1. harder to breathe out

2. Loss of elastin around alveoli → Reduces elastic recoil

3. The reduced radial traction causes the airways to collapse

4. Air in alveoli become trapped

The 2 major patterns of emphysema (2)(2)

1. Centriacinar emphysema

   1. Respiratory bronchiole affected

2. Panacinar emphysema

   1. Entire acinus affected

Centriacinar emphysema

• Acinus involvement

• Main cause

• Lobe involvement

• Typical age of presentation

• Main symptom

• Prevalence

• Acinus involvement - Respiratory bronchiole

• Main cause - Cigarette smoking

• Lobe involvement - More common upper lobes

• Typical age of presentation - 6th and 7th decade

• Main symptom - Dyspnea

• Prevalence - More

Panacinar emphysema

• Acinus involvement

• Main cause

• Lobe involvement

• Typical age of presentation

• Main symptom

• Prevalence

• Acinus involvement - Entire acinus

• Main cause - Alpha 1 - antitrypsin deficiency

• Lobe involvement - More common lower lobes

• Typical age of presentation - 4th and 5th decade

• Main symptom - Dyspnea

• Prevalence - Less

emphysema Dyspnea cause

Decreased gas exchange/obstruction

emphysema Hyperinflation of lung (barrel chest) cause

Destruction of elastin, collagen → Inspiration is easy Expiration is difficult

emphysema Weight loss cause

Decreased gas exchange/obstruction

The clinical features of emphysema (2)

1. Ventilation perfusion mismatch → Hypoxemia → Increases ventilation rate → Helps maintain blood oxygenation at rest

2. Until late in the disease when they become hypoxemic and cyanotic

Gross appearance of lungs with Centriacinar emphysema

Dilated airspaces with loss of lung tissue → Voluminous lungs

Name

Bullous emphysema