ARDS

Question 1

What is ARDS? (think 3 key parts/characteristics)

Answer 1

(1) acute lung injury with (2) diffuse alveolar damage –> (3) pulmonary edema that is non cardiogenic

Question 2

ARDS is usually seen unilaterally or bilaterally?

Answer 2

bilaterally

Question 3

What are the 4 criteria for ARDS?

Answer 3

1. acute onset of respiratory failure
2. bilateral infiltrate on CXR
3. absence of LA hypertension
4. PaO2/PiO2 < 200 (<300 is mild injury)

Question 4

What is the mechanism of lung injury in ARDS?

Answer 4

Activation of inflam mediators –> damage to capillary endo- and alveolar epi-thelial cells –> inc permeability –> influx of edema and inflam cells into airspace –> dysfunction of surfactant

Question 5

What are the causes of ARDS?

Answer 5

Direct:

• pneumonia
• aspiration of gastric contents
• pulm contusion
• fat emboli
• near drowning
• inhalation injury

Indirect:

• sepsis
• shock
• drug overdose
• cardio-pulmonary bypass
• acute pancreatitis
• transfusion of blood products

Question 6

What are the stages of ARDS

Answer 6

Exudate
proliferative
fibrotic
recovery

Question 7

What factors increase the risk of death at the time of ARDS diagnosis?

Answer 7

1. chronic liver disease
2. non-pulmonary organ dysfuction
3. sepsis
4. advanced age

Question 8

What causes the severe hypoxemia assc with ARDS?

Answer 8

shunting of blood

Question 9

In ARDS compliance is (inc or dec)

Answer 9

acutely decreased (due to hyaline memb? deposition)

Question 10

What is PEEP? How does it help pts with ARDS?

Answer 10

Positive End Expiratory Pressure
it improves oxygenation by recruiting atelectatic alveoli and increases FRC by redistributing fluid to allow gas exchange
**counterbalances the pressure of fluid to keep alveoli open

Question 11

What is the mortality of pts with ARDS? What is death usually caused by?

Answer 11

30-40%

multi organ failure

Question 12

When is pneumothorax seen in ARDS?

Answer 12

after 2nd week of illness

Question 13

What reduces mortality in ARDS?

Answer 13

use of lower tidal volume during mechanical ventilation

-decreased lung injury and therefore decreased circulating inflam mediators

Question 14

What can decrease the days spent on mechanical ventilation for pts with ARDS?

Answer 14

conservative fluid management

Question 15

What can imporove oxygenation but does not improve mortality?

Answer 15

NO and prone ventilation

Question 16

How is the lung function of ARDS survivors?

Answer 16

• mild to moderate restrictive ventilatory defect with mild reduction in diffusion capacity (DLCO)
• scaring depends on severity of disease
• some may heal completely if disease was mild