Interstitial Lung Disease and ARDS - 1 Flashcards

1
Q

Normally alveolar septae are very thin and composed of what?

A

single layer of pneumocytes

capillary and

small amount of connective tissue (mainly elastic fibers)

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2
Q

How do ILD’s affect alveolar interstitium?

A

add cells and fibrous tissue to the interstitium.

This:

Thickens and stiffens the septae and

Restricts stretching,

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3
Q

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

A

decreased filling of lungs upon inspiration

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4
Q

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

A

increased recoil of lungs on expiration

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5
Q

Restrictive lung diseases are characterized by what?

A

reduced lung compliance

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6
Q

What is the meaning of FEV 1?

A

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

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7
Q

What does FVC mean?

A

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

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8
Q

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

A

decreased

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9
Q

What are some C/F of interstitial lung disease?

A
  • 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
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10
Q

What is the pathology of one with interstitial lung disease?

A

Diffuse fibrosis of alveolar interstitium

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11
Q

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

A

diffuse infiltrate (ground glass shadows)

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12
Q

What is this picture depicting?

A

Interstitial fibrosis

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13
Q

What is this picture depicting?

A

ground glass opacities (interstitial fibrosis)

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14
Q

What are the two classifications of restrictive lung disease?

A

acute: ARDS
chronic: Based on etiology

Classified into 2 major groups:

ILD with known cause

ILD with unknown cause

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15
Q

Chronic ILD comes from what exposure in general?

A

occupational and environmental exposures

Drug or treatment related

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16
Q

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

A

pneumoconiosis:

asbestosis

silicosis

coal worker’s pneumoconiosis

berylliosis

17
Q

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

A

Hypersensitivity pneumonitis

18
Q

What are some drug related causes of chronic ILD?

A

Chemotherapeutic agents:

Busulfan, bleomycin, methotrexate

Ionizing radiation

19
Q

What are some forms of ILD with unknown causes?

A
  1. Sarcoidosis
  2. Pulmonary hemorrhage syndrome
  3. Idiopathic pulmonary fibrosis
  4. Collagen vascular diseases
  5. Eosinophilic granuloma
20
Q

What are some examples of pulmonary hemorrhage syndromes?

A
  1. Goodpasture syndrome
  2. Wegener’s granulomatosis
  3. Idiopathic hemosiderosis
21
Q

ARDS is a clinical syndrome characterized by what?

A

Diffuse alveolar capillary damage with resultant

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

22
Q

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

A

ARDS acute respiratory distress syndrome

23
Q

In simple words ARDS means what?

A

noncardiogenic pulmonary edema resulting from acute damage to alveoli

24
Q

What are some synonyms for ARDS?

A

shock lung, diffuse alveolar damage (DAD)

25
Q

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

A

Aspiration of gastric contents.

Smoke inhalation

Pneumonia

26
Q

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

A

Endotoxic or septic shock (most common cause)**

Severe trauma with shock

Drugs : heroin, bleomycin etc.

Toxemia of pregnancy

Amniotic fluid embolism

27
Q

What are the 2 factors responsible for ARDS?

A
  1. Damage to alveolar capillary endothelium and alveolar epithelium
  2. Damage to type II pneumocytes
28
Q

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

A

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

29
Q

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

A
  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)
30
Q

Gross morphology of lungs with ARDS?

A

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

31
Q

Microscopy of early findings of lungs with ARDS?

A

Diffuse alveolar damage and necrosis

Alveolar edema, Collapsed alveoli

Some alveoli lined by hyaline membrane

32
Q

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

A

Repair by type II pneumocytes

Progressive interstitial fibrosis (restrictive lung disease)

33
Q

What is the pathogenesis of hyaline membrane formation?

A

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

34
Q

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

A

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)

35
Q

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

A

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

36
Q

What is the prognosis of patients with late stage ARDS?

A

mortality almost 60% even with improved methods

37
Q

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

A

Obstructive FEV1 is really low compared to FVC > ratio < 80%

Restrictive FVC is much lower when compared to FEV1 and therefore ratio is > 80%