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Flashcards in PATHOPHYS Deck (21)
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1
Q

what is the most common predisposing factor to ALI/ARDS?

A

sepsis

2
Q

what is alveolar dead space?

A

alveoli ventilated but no perfused, so cannot participate in gas exchange

3
Q

can increasing alveolar dead space be normal?

A

NO, increased alveolar dead space is ALWAYS PATHOLOGIC

4
Q

what is the normal value of tissue O2 consumption ?

A

250 mL/min

5
Q

What is the normal value for PAO2?

A

100 mmHg

6
Q

How do you define hyperventilation?

A

ventilating more than your metabolic needs defined by low arterial CO2

7
Q

How do you calculate the A-a gradient?

A

PAO2-PaO2

8
Q

what can a widened A-a gradient tell you?

A

signifies the presence of lung disease (in other words if its normal then the problem is not due to parenchymal lung disease)

9
Q

define hypoxemia

A

decreased oxygen tension in the circulating blood compared to normal

10
Q

what are the 5 causes of hypoxemia?

A

Normal A-a difference: decreased, PIO2, Hypoventilation

Widened A-a difference: diffusion limitation, R to L shunt, V/Q mismatch

11
Q

What can a diffusion capacity test tell you?

A

only that there is a diffusion problem, won’t tell you exactly why

12
Q

normal transit time of rbc in pulmonary capillary

A

0.75 seconds

13
Q

with normal diffusion capacity how long does it take for a rbc to reach equilibrium with PAO2?

A

0.25s

14
Q

what are the 2 ways hypoxemia can occur with a diffusion limitation?

A
  1. diffusion capacity severely decreased to <0.25s
15
Q

does abnormal diffusion normally cause hypoxemia at rest?

A

NO, but can contribute lower PaO2 during exercise

16
Q

How can you treat a suspected diffusion limitation problem?

A

give 100% FiO2, reverses hypoxemia and normalizes A-a gradient

17
Q

what happens when you give supplemental oxygen to a person with R to L shunt?

A

hypoxemia does not correct with increased FiO2

18
Q

what is the most common cause of hypoxemia?

A

V/Q mismatch

19
Q

Does V/Q mismatch correct with supplemental O2?

A

yes

20
Q

what is the major risk you are taking if you prescribe a long acting beta agonist?

A

associated w/ increased mortality

21
Q

what are the major mediators of airway inflammation in asthma?

A
eosinophils
basophils, mast cells
TH2 cells
major basic protein
eosinophilic cationic protein
histamine
LTs, prostaglandins
IgE
vagal affarent, efferent
IL-5, PAF