ARDS Flashcards

1
Q

Berlin definition of ARDS

A

Onset of symptoms and signs are within 1 week of insinuating event

Hypoxemia is present

Chest xray shows bilateral opacities that are non-cardiogenic in etiology (not caused by heart failure)

PaO2/FiO2 < 300 mmHg

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2
Q

Pathophysiology of ARDS

A

Some sort of insult causes damage to capillary endothelium and alveolar epithelium

Results in diffuse alveolar disease/ hyaline membrane disease
- hyaline cartilage develops to alveoli damage

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3
Q

Possible causes for ARDS

A

Alveoli can be direct (pneumonia, lung contusion, near drowning, smoke inhalation) or indirect (sepsis, burns, emboli from fractures, TRALI, pancreatitis, OD).

  • if direct, release of pro-inflammatory cytokines are induced and includes TNF and ILs
  • cytokines recruit neutrophils and release toxic mediators and ROS
  • causes tissue destruction
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4
Q

What is the most common cause of ARDS?

A

Sepsis, usually secondary to pneumonia

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5
Q

3 phases of ARDS

A

Exudative (1-7 days)

  • hyaline membrane production begins and edema is present (exudate)
  • diffuse alveolar damage is present
  • shows bilateral opacities
  • lungs are stiff w/ VQ mismatch and increased dead space
  • respiratory failure may occur here

Proliferative (7-21st day)

  • often cured here*
  • removed from ventilators sometimes
  • reparative processes begin here with type 2 pneumocystis proliferating along alveolar basement membranes
  • new surfactant and type 1 pneumocystis production begins

Fibrotic (21st day+)

  • require long-term ventilators
  • resembles emphysema
  • interstital fibrosis is widespread
  • pulmonary hypertension begins
  • high rate of death if at this stage (53%)
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6
Q

Non-cardiogenic pulmonary edema

A

Looks similar to cardiogenic pulmonary edema except:

1) Normal hydrostatic pressure with loss of oncotic pressure (no pulmonary hypertension < 25mmHg)
2) heart size is normal

3) if you can get fluid, exudate is rich in
proteins

4) BNP will not be elevated
5) ECG shows nothing abnormal
6) no JVD present

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7
Q

Cardiac ultrasound with heart failure vs ARDS

A

HF:

  • low ejection fraction
  • dilated left ventricle/atrium
  • overall structure looks different

ARDS:
- none of the above present

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8
Q

Severity of ARDS

A

Measured by ratio of paO2/FiO2
- partial pressure of oxygen/ fraction of inspired O2 (in decimal form)

Mild = ratio is >200 but less than 300mmHg

Moderate = ratio is >100 but less than 200 mmHg

Severe = ratio is <100 mmHg

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9
Q

Treatment of ARDS

A
Require ventilator (but try to limit use)
- also patient must be prone 

Fluid management without excess IV fluids

DONT use glucocorticoids or surfactant replacement

Can use PEEP to prevent persistent alveoli collapse (usually 5mmHg)

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