ACP L19 Obstructive and restrictive lung diseases

Question 1

Name the respiratory units of the lung.

Answer 1

Respiratory bronchioles and alveolar ducts > alveolar sacs

Question 2

What is the definition of obstructive lung disease? Mechanism?

Answer 2

Progressive, largely irreversible obstruction to airflow

• increased resistance to airflow, obstruction at any level

(blowing a balloon with the tightened neck)

Question 3

What is the definition of restrictive lung disease?

Answer 3

Reduced total lung capacity

• reduced expansion of lung parenchyma

(like a balloon in a box)

Question 4

Give examples of obstructive lung diseases. (4)

Answer 4

1. Narrowing airway
   - asthma
   - chronic bronchitis
   - bronchiectasis
2. Loss of elastic recoil
   - emphysema

Question 5

Give examples of restrictive lung diseases. (7)

Answer 5

1. Chest wall disorder
   - obesity
   - kyphoscoliosis
   - pleural disease
   - GBS
2. Acute interstitial disease: - - Adult respiratory distress syndrome (ARDS)
3. Chronic interstitial disease: - IPF (idiopathic pulmonary fibrosis)
   - pneumoconiosis
   - sarcoidosis

Question 6

Spirometry findings in Obstructive lung disease?

Answer 6

Reduced FEV1 > reduced FVC

Ratio is <0.7

Question 7

Spirometry findings in Restrictive lung disease?

Answer 7

Reduced FEV1/FVC, ratio normal

Question 8

What is FEV1 and definition?

Answer 8

Forced expiratory volume - greatest volume of air that can be breathed out in the 1st second of breath

Question 9

What is FVC and definition?

Answer 9

Forced vital capacity: the greatest volume of air that can be breathed out in a single large breath

Question 10

What are the complications of chronic obstructive airway diseases? (5)

Answer 10

1. Acute exacerbation of COPD
2. Pulmonary hypertension, cor pulmonale ( :( lung > heart)
3. Pneumothorax
4. Respiratory failure
5. Secondary polycythemia (hypoxia drives increased production of erythrocytes)

Question 11

What is the definition of emphysema histopathologically?

Answer 11

Permanent enlargement of airspaces distal to terminal bronchioles, accompanied by destruction of their walls

WITHOUT obvious fibrosis

Question 12

What is panacinar and centriacinar emphysema?

Answer 12

Centriacinar emphysema: respiratory bronchioles at upper lobe

Panacinar emphysema: whole acini at lower lobe

Question 13

What is the difference in V/Q and ABG between panacinar and centriacinar emphysema?

Answer 13

Centriacinar:
1. V/Q: reduced, gas exchange still takes place at alveoli
(less air available for gas exchange)

2. ABG: severe change

Panacinar:
1. V/Q: Normal: reduced V = reduced Q

2. ABG: less drastic

Question 14

What are the respective causes of panacinar and centriacinar emphysema?

Answer 14

Panacinar:
- AAT (alpha1-antitrysin deficiency)

Centriacinar:
- smoking, pneumonia

Question 15

Paraseptal/ distal acinar emphysema forms bulla and causes?

Answer 15

pneumothorax

Question 16

Read:
Pathogenesis of Alpha1 antitrypsin deficiency caused - emphysema

1. Protease-antiprotease imbalnce
   Alpha1 antitrypsin: major inhibitor of protease (against elastin produced by neutrophils by Pi locus)
2. Oxidant-antioxidant imbalance
   - ROS from tobacco >
   a. inactivate AAT > functional AAT deficiency
   b. deplete antioxidant (e.g. GSH)

Answer 16

Consequences: loss of elastic tissues > reduced elastic recoil > airway collapse during expiration

Question 17

Manifestations of emphysema?

Answer 17

Pink puffer:

• early dyspnea
• late hypoxemia
• respiratory alkalosis

Question 18

What to expect to see on CXR for emphysema patients? (3)

Answer 18

1. hyperinflated lungs
2. flattened diaphragm
3. Vertically oriented heart