ARDS

Question 1

Three characteristics of pulmonary edema:

Answer 1

1. Heavy, wet lungs: basal initiation (dependent edema)
2. Hemodynamic: Cardiogenic
3. Permeability: increased capillary permeability

Question 2

Pulmonary edema: hemodynamic characteristics

Answer 2

1. Increased hydrostatic pressure: left sided CHF
2. Engorged alveolar capillaries
3. Intra-alveolar granular pink precipitate
4. Alveolar microhemorrhages
5. Hemosiderin-laden mac’s (heart cells)

Question 3

What are the consequences of long-standing pulmonary edema?

Answer 3

1. Mitral stenosis
2. Increased heart cells
3. Fibrosis and thickening of alveolar walls
4. Soggy lungs become brown and indurated (firm or hard due to fibrous elements)

Question 4

What are the characteristics of microvascular injury in pulmonary edema?

Answer 4

1. Injury to capillaries of the alveolar septa
2. Primary injury to the vascular endothelium or alveolar epithelial cells: no increase of hydrostatic pressure.
3. Fluid and proteins into interstitial space and potentially alveoli
4. Pneumonia=localized edema

Question 5

Diffuse alveolar damage (DAD) morphology: acute

Answer 5

1. Congestion, interstitial, and intra-alveolar edema, inflammation and fibrin deposition.
2. Fibrin rich edematous fluid with cytoplasmic and lipid remnants, necrotic epithelial cells.

Question 6

DAD morphology: organizing type

Answer 6

1. Type II pneumocytes (**) undergo proliferation
2. Results in organizing fibrin exudate and intra-alveolar fibrosis
3. Leads to more pneumocyte proliferation and collagen deposition.

Question 7

ARDS onset:

Answer 7

Rapid
Respiratory insufficiency
Cyanosis
Arterial hypoxemia (refractory oxygen therapy)
Multi-organ failure

Question 8

Chest radiographs of ARDS reveal what?

Answer 8

Diffuse alveolar infiltrates

Question 9

ARDS causes: infectious

Answer 9

Sepsis
Viral
Mycoplasma
Pneumocystis 
Miliary TB
Gastric aspiration

Question 10

ARDS causes: physical

Answer 10

Mechanical trauma/head injuries

Burns and radiation

Question 11

ARDS causes: inhaled irritants

Answer 11

Smoke
Gases
Chemicals

Question 12

ARDS causes: chemical

Answer 12

Heroin
Aspirin (ASA)
Barbituates

Question 13

ARDS causes: hematologic

Answer 13

TACO

DIC

Question 14

Other causes of ARDS:

Answer 14

Pancreatitis
Uremia
Bypass Sgx

Question 15

What happens in ARDS?

Answer 15

1. Capillary endothelial or alveolar epithelial injury.
2. Increased vascular permeability and flooding.
3. Decreased diffusion capacity.
4. Surfactant abnormalities (damaged Type II pneumos)

Question 16

ARDS in the long run, what happens?

Answer 16

Exudate and destruction are poorly resolved.

Leads to organization and scarring-chronic disease

Question 17

Immune responses due to ARDS:

Answer 17

1. Elevated pro-inflammatory mediators.
2. Decreased anti-inflammatory molecules.
3. Proinflammatory: NF-kB (required)
4. Bacterial infection: toll-like receptors–> innate immune response–> NF-kB
   * Effects transcriptional selectivity (increased IL-10)

Question 18

Immediate immunologic reaction to ARDS: what is released?

Answer 18

IL-8:

• neutrophilic chemotactic and activating agent
• Pulmonary macrophages

Question 19

Released IL-1 and TNF role in ARDS?

Answer 19

Further activation and sequestration of neutrophils.

Vascular spaces, intersititium, and alveoli

Question 20

Other things released by ARDS?

Answer 20

Oxidants
Proteases
Platelet-activating factor
Leukotrienes

Question 21

ARDS presentations clinically:

Answer 21

1. Radriographs normal at first
2. Non-homogenous spread.
3. Decreased functional lung volume.
4. VQ mismatch
5. 60% mortality

Question 22

Acute interstitial pneumonia

Answer 22

1. Widespread acute lung injury
2. Unknown cause
3. 50 years of age without sex predilection.
4. Presents like URTI
5. Progresses similar to ARDS
6. 50% mortality