Interstitial Lung Disease and ARDS - 1

Question 1

Normally alveolar septae are very thin and composed of what?

Answer 1

single layer of pneumocytes

capillary and

small amount of connective tissue (mainly elastic fibers)

Question 2

How do ILD’s affect alveolar interstitium?

Answer 2

add cells and fibrous tissue to the interstitium.

This:

Thickens and stiffens the septae and

Restricts stretching,

Question 3

What is reduced lung compliance? (or rather what does it cause)

Answer 3

decreased filling of lungs upon inspiration

Question 4

What does increased elasticity mean for the lungs? (upon expiration)

Answer 4

increased recoil of lungs on expiration

Question 5

Restrictive lung diseases are characterized by what?

Answer 5

reduced lung compliance

Question 6

What is the meaning of FEV 1?

Answer 6

forced expiratory volume in 1 second (FEV1) is the maximum amount of air that the subject can forcibly expel during the first second following maximal inhalation

Question 7

What does FVC mean?

Answer 7

Forced vital capacity (FVC).
This is the amount of air exhaled forcefully and quickly after inhaling as much as you can.

Question 8

Are obstructive diseases characterized by increased or decreased FEV 1/FVC ratios?

Answer 8

decreased

Question 9

What are some C/F of interstitial lung disease?

Answer 9

• Stiff lung > increased effort of breathing > DYSPNEA
• DRY COUGH
• Ventilation perfusion abnormalities > Hypoxia > pulmonary hypertension > cor pulmonale >Respiratory failure
• All lung volumes and capacities are decreased
• Increased FEV 1sec / FVC ratio

Question 10

What is the pathology of one with interstitial lung disease?

Answer 10

Diffuse fibrosis of alveolar interstitium

Question 11

Upon completing a chest radiograph what would one find of a person with interstitial lung disease?

Answer 11

diffuse infiltrate (ground glass shadows)

Question 12

What is this picture depicting?

Answer 12

Interstitial fibrosis

Question 13

What is this picture depicting?

Answer 13

ground glass opacities (interstitial fibrosis)

Question 14

What are the two classifications of restrictive lung disease?

Answer 14

acute: ARDS
chronic: Based on etiology

Classified into 2 major groups:

ILD with known cause

ILD with unknown cause

Question 15

Chronic ILD comes from what exposure in general?

Answer 15

occupational and environmental exposures

Drug or treatment related

Question 16

What are some inorganic exposures due to occupational and environmental exposures that could lead to chronic ILD?

Answer 16

pneumoconiosis:

asbestosis

silicosis

coal worker’s pneumoconiosis

berylliosis

Question 17

What are some organic occupational and environmental exposure causes of chronic ILD?

Answer 17

Hypersensitivity pneumonitis

Question 18

What are some drug related causes of chronic ILD?

Answer 18

Chemotherapeutic agents:

Busulfan, bleomycin, methotrexate

Ionizing radiation

Question 19

What are some forms of ILD with unknown causes?

Answer 19

1. Sarcoidosis
2. Pulmonary hemorrhage syndrome
3. Idiopathic pulmonary fibrosis
4. Collagen vascular diseases
5. Eosinophilic granuloma

Question 20

What are some examples of pulmonary hemorrhage syndromes?

Answer 20

1. Goodpasture syndrome
2. Wegener’s granulomatosis
3. Idiopathic hemosiderosis

Question 21

ARDS is a clinical syndrome characterized by what?

Answer 21

Diffuse alveolar capillary damage with resultant

Increased capillary permeability causing leakage of protein rich fluid into alveoli and severe pulmonary edema.

Question 22

What condition is being described?

Marked by formation of intra-alveolar hyaline membrane (composed of fibrin and cellular debris)

Results in severe impairment of gas exchange with consequent hypoxia (respiratory failure) refractory to oxygen therapy.

Patients present with: severe acute dyspnea and hypoxemia non responsive to 100% oxygen

Answer 22

ARDS acute respiratory distress syndrome

Question 23

In simple words ARDS means what?

Answer 23

noncardiogenic pulmonary edema resulting from acute damage to alveoli

Question 24

What are some synonyms for ARDS?

Answer 24

shock lung, diffuse alveolar damage (DAD)

Question 25

What are some conditions associated with development of acute respiratory distress syndrome? (direct injury to lung)

Answer 25

Aspiration of gastric contents. Smoke inhalation Pneumonia

Question 26

What are some conditions leading to indirect injury to the lung that are associate with development of acute respiratory distress syndrome?

Answer 26

Endotoxic or septic shock (most common cause)\*\* Severe trauma with shock Drugs : heroin, bleomycin etc. Toxemia of pregnancy Amniotic fluid embolism

Question 27

What are the 2 factors responsible for ARDS?

Answer 27

1. Damage to alveolar capillary endothelium and alveolar epithelium 2. Damage to type II pneumocytes

Question 28

Describe pathogenesis of ARDS destroying alveolar capillary epithelium and type II pneumocytes.

Answer 28

Damage mediated by neutrophils and alveolar macrophages. Alveolar macrophages release cytokines: Cytokines are chemotactic to neutrophils Neutrophils transmigrate into alveoli through pulmonary capillaries and damage type I and type II pneumocytes -Decrease in surfactant causes atelectasis Capillary damage causes leakage of protein rich exudate producing hyaline membranes

Question 29

What are the consequences of injury to pneumocytes and alveolar capillary endothelium?

Answer 29

1. Damage to pulmonary capillaries (leaky capillary syndrome) \> pulmonary edema, protein leakage 2. Formation of hyaline membrane (from protein leakage) 3. Damage of type II pneumocytes (loss of surfactant) \> contributes to atelectasis (collapse of alveoli) …..In combination with pulmonary edema responsible for stiff lungs (chr or ARDS)

Question 30

Gross morphology of lungs with ARDS?

Answer 30

lungs are dark red, airless and firm (liver-like)

Question 31

Microscopy of early findings of lungs with ARDS?

Answer 31

Diffuse alveolar damage and necrosis Alveolar edema, Collapsed alveoli Some alveoli lined by hyaline membrane

Question 32

What is the microscopic morphology of late findings (proliferative stage) of cells with ARDS?

Answer 32

Repair by type II pneumocytes Progressive interstitial fibrosis (restrictive lung disease)

Question 33

What is the pathogenesis of hyaline membrane formation?

Answer 33

Alveolar hyaline membranes consist of fibrin-rich edema fluid mixed with the cytoplasmic and lipid remnants of necrotic epithelial cells

Question 34

How does the pathogenesis differ in hyaline membrane disease in newborns? (ARDS)

Answer 34

The mechanism of respiratory distress syndrome of the newborn is a deficiency of surfactant, whereas in ARDS the mechanism is damage to the alveolar epithelium (diffuse alveolar damage)

Question 35

With continue proliferation in ARDS of fibroblasts, what type of lung disease develops in this patients?

Answer 35

While complete resolution may occur, hyperplasia of type II alveolar pneumocytes plus intra-alveolar fibrosis are common sequelae Marked thickening of the alveolar walls and interstitial fibrosis may persist, giving rise to restrictive lung disease

Question 36

What is the prognosis of patients with late stage ARDS?

Answer 36

mortality almost 60% even with improved methods

Question 37

Compare and contrast FEV1/FVC ratio in restrictive vs obstructive lung diseases.

Answer 37

Obstructive FEV1 is really low compared to FVC \> ratio \< 80% Restrictive FVC is much lower when compared to FEV1 and therefore ratio is \> 80%