ARDS - Muthiah (Good, Good)

Question 1

What is the definition of ARDS w/ regards to 
1 - onset 
2 - type of damage
3 - type of edema 
4 - infiltrates

Answer 1

1 - acute, severe
2 - diffuse alveolar damage
3 - microvascular permability leading to non-cardiogenic pulmonary edema
4 - BILATERAL infiltrates

Question 2

is ARDS responsive or refractory to O2? (hypoxemia)

Answer 2

ARDS is an acute refractory hypoxemia

Question 3

is ARDS a VQ mismatch or shunt?

Answer 3

shunt

Question 4

ARDS - What are the 4 Berlin Criteria

Must Know

Answer 4

1 - acute onset of respiratory failure
2 - bilateral infiltrates on CXR
3 - NO evidence of volume overload
4 - PaO2/FiO2 less than 300

Question 5

what type of leukocytes should predominate in a bronchial alveolar lavage of normal pt?

Answer 5

macrophages

Question 6

bronchial alveolar lavage of ARDS pt will see predominantly what type of leukocyte?

Answer 6

neutrophils - ARDS mechanism of lung injury is an inflammatory process - exudate containing neutrophils filling alveoli

Question 7

what is the actual barrier to diffusion in ARDS? What causes it

Answer 7

hyaline membrane - caused by influx of protein rich edema fluid and inflammatory cells into air spaces

Question 8

what causes alveolar collapse in ARDS?

Answer 8

inflammatory damage to type II pneumocytes causes dysfunction of surfactant - collapses of alveoli

Question 9

what are the 5 direct causes of ARDS?

Answer 9

1 - pneumonia / aspiration of gastric contents or other causes of chemical pneumonitis
2 - pulmonary contusion, penetrating lung injury
3 - fat emboli
4 - near drowning
5 - inhalation injury

Question 10

What is the link between sepsis and ARDS? What is the pathophys behind a pt with sepsis developing ARDS?

Answer 10

inflammation can spread via cytokines, and 100% of blood goes through pulmonary circulation

Question 11

What are the 7 indirect causes of ARDS?

number 1 and 5 are key to know

Answer 11

1 - sepsis
2 - severe trauma w/ shock hypoperfusion
3 - drug over dose
4 - cardiopulmonary bypass
5 - acute pancreatitis
6 - transfusion of blood products
7 TRALI - transfusion related acute lung injury

Question 12

where does the excess lung fluid consolidate (dorsal or ventral) and why

Answer 12

it consolidates dorsally due to the effects of gravity (the dependent portion of the lung is dorsal)

Question 13

consolidation of lung fluid dorsally - what does this mean in terms of V/Q ratio

Answer 13

the dorsal portion of lungs, again b/c gravity, have most blood flow but least amount of ventilation (b/c of shunt) - this is why putting pt prone helps so much

Question 14

if you put in an endotracheal tube, what relationship should it have to the carina? (he said we might be asked about this)

Answer 14

the tip of the endotracheal tube should be 1 - 1.5 inches above the carina

Question 15

what are the 4 predictors of bad outcome for ARDS? (increased risk of death in ARDS) - this was on his USMLE

Answer 15

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

Question 16

(clicker) - pt with pneumonia is undergoing mechanical ventialtion following onset of ARDS - currently on 100% osygen, and PEEP of 5, but his O2 sat is only 75% - how do we inc his sat?

Answer 16

inc the PEEP

Question 17

why do you not want to inc the tidal volume in a pt w/ ARDS who has low sat?

Answer 17

inc tidal volume will cause more stretching of alveolar cells, and the more stretching will cause more inflammation

Question 18

what is the possible mechanism of improvement in oxygenation with the application of PEEP in pts with ARDS? (clicker)

Answer 18

recruiting atelectatic alveoli and increasing FRC - PEEP provides more “back pressure” during exhalation, helps to keep airways and alveoli open during exhalation

Question 19

what is the other potential mechanism of imporvement in ARDS by inc PEEP, specifically w/ regards to lung water?

Answer 19

inc PEEP causes a redistribution (NOT reduction) of lung water

Question 20

what is the importance of FRC when applied to holding ones breath or during the process fo intubation

Answer 20

the higher the FRC, the longer you can maintain a high O2 sat. pts w/ low FRC - pregnant ladies or obese pts - during intubation their sats will drop quickly

Question 21

ARDS is characterized by what change in pulmonary compliance?

Answer 21

acute decrease in pulmonary compliance

Question 22

he had another clicker about dec the tidal volume for ARDS, and how it showed a reduction in mortality

Answer 22

he says will be on boards -

Question 23

when is the incidence of penumothorax as a complication of ARDS usually seen?

Answer 23

After 2 weeks of ARDS onset (need to know)

Question 24

death in a patient due to ARDS is uaully a result of

Answer 24

multi-organ failure

Question 25

the severe hypoxemia seen in ARDS does not adequately respond to supplemental oxygen, signifying the main mechanism of hypoxemia to be

Answer 25

shunt (must know, will be on step)

Question 26

what is the central pathogenic mechanism of ARDS?

Answer 26

raging inflammation

Question 27

given that the central pathogenic mech of ARDS is raging inflammation, what possible pharmacological management does he mention that he uses, but is controversial?

Answer 27

corticosteroids

Question 28

USMLE: ARDS what type of respiratory failure, acute or insidious?

Answer 28

acute

Question 29

USMLE: pathogenic mechanism of ARDS

Answer 29

intense inflammation

Question 30

USMLE: common precipitating causes of ARDS (4)

Answer 30

pneumonia sepsis trauma aspiration

Question 31

USMLE: what type of pulmonary edema is present in ARDS

Answer 31

non-cardiogenic

Question 32

USMLE: what is the mechanism causing severe hypoxemia seen in ARDS

Answer 32

shunt

Question 33

USMLE: ARDS is associated with what change in lung compliance

Answer 33

decreased lung compliance

Question 34

USMLE: what management strategy is used with mechanical ventilation to improve oxygenation

Answer 34

PEEP

Question 35

USMLE: how does PEEP help improve oxygenation in ARDS

Answer 35

recruits atelectatic alveoli and increases FRC

Question 36

USMLE: what is the mortality rate for ARDS?

Answer 36

30-40%

Question 37

USMLE: what is most common COD for ARDS

Answer 37

pts w/ ARDS die from multi organ failure

Question 38

USMLE: when do you see pneumothorax in ARDS

Answer 38

seen after 2nd week of onset of ARDS

Question 39

USMLE: what management strategy used during mechanical ventilation reduces mortality?

Answer 39

lower tidal volume

Question 40

USMLE: what management strategy will decrease the number of days on a mechanical ventilator?

Answer 40

conservative fluid management

Question 41

USMLE: survivors of ARDS have what ventilatory defect and what change in DLCO

Answer 41

mild to moderate restrictive ventilatory defect | mild reduction in DLCO

Question 42

USMLE: what recent trial for management strategy was shown to improve mortality of ARDS - ventilation strategy

Answer 42

prone ventilation

Question 43

USMLE: what management strategy helps to improve oxygenation but does not improve mortality at the current time

Answer 43

nitric oxide