Lecture 37+38 Flashcards

1
Q

what is the ideal V/Q ratio

A

4/5 or 0.80

V = 4 L /min 
Q = 5L/min
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2
Q

compliance of the lung?

A

The apex of the lung is more compliant compared to the base of the lung

the apex of the lung is always distended

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3
Q

ventilation vs perfusion at the apex and base of lung?

where is gas exchange more efficient?

A

ventilation is higher at the bottom of the lung compared to the top

perfusion is higher at the bottom compared to the top

The V/Q ratio is higher at the apex compared to the base

gas exchange is more efficient at the apex of the lungs compared to the base

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4
Q

what happens for low V/Q ratios and high V/Q ratios

A

low = hypoxic vasoconstriction

high = bronchoconstriction

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5
Q

how does altering V/Q effect PO2 and PCO2?

A

low V/Q = low PO2 and high PCO2

high V/Q = high PO2 and low PCO2

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6
Q

A-a O2 gradient equation

A

PAO2 - PaO2

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7
Q

What increases the A-a O2 gradient?

A

reginal low V/Q ratio

anatomic shunt

diffusion block

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8
Q

what leads to hypoxemia if the A-a gradient is normal?

A

hypoventilation

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9
Q

what leads to hypoxemia if the A-a gradient is abnormal and it is not corrected with oxygen therapy?

A

shunt

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10
Q

what leads to hypoxemia if the A-a gradient is abnormal and it is corrected with oxygen therapy?

A

It is either a V/Q mismatch or diffusion problem

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11
Q

what is the diagnosis if the DL co is normal or abnormal?

A

normal = V/Q mismatch

abnormal = diffusion problem

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12
Q

what does increased altitude do to hypoxemia?

A

increases it!

ventilation is increased

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13
Q

equation for saturation

A

SO2 = HbO2 content / HbO2 capacity x 100%

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14
Q

O2 saturation curve?

loading phase? unloading phase?

A

loading phase: O2 content and saturation remains fairly constant over a range of partial pressures (lungs)

unloading: steep portion of the curve that allows for the release of O2 into tissues

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15
Q

saturation curve and P50?

what does an increase or decrease in P50 do?

A

P50 is when Hb is at 50 percent capacity

decrease: left shift (harder to unload)
increase: right shift (easier to unload)

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16
Q

what also moves the saturation curve to the right?

A

increased temp

low pH

increase in PCO2

increase in 2,3 BPG

this lowers O2 affinity for easy unloading

17
Q

O2 saturation curve and anemia?

A

saturation and partial pressure remain the same

the only change is O2 content, thus curve is lower

18
Q

does polycythemia improve oxygenation?

A

No

no change in oxygen affinity

19
Q

O2 saturation and CO poisoning

Treatment?

A

Low O2 content

cherry red blood; not cyanotic

treatment:
administer 100 percent oxygen or O2 with 5% CO2 to improve alveolar ventilation

20
Q

what is Fick’s law equation?

A

Vgas = A x D x deltaP / T

21
Q

How to find DL

A

Vco / PACO