Pitfalls Of ABGs Flashcards

0
Q

What should the venous PvO2 usually be?

A

Less than 40 mmHg

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1
Q

What should you look for when performing an ABG?

A

Blood pulsating syringe

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2
Q

What should venous saturation be?

A

Less than 75%

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3
Q

What two things will be close to arterial values, making it hard to differeniate?

A

pH and pvo2

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4
Q

If the fio2 is changed, how long should it take normal patients to achieve a steady state?

A

3 minutes

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5
Q

If the fio2 is changed, how long should it take chronic obstructive patients to achieve a steady state?

A

20 minutes

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6
Q

What does heparin cause?

A

A drop in the paco2

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7
Q

When is heparin most frequently found in an ABG?

A

When the blood is drawn from an indwelling catheter

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8
Q

What kind of ph does heparin have?

A

Slightly acidic

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9
Q

What can offset the acidic ph of heparin?

A

Any rise in blood ph when paco2 false

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10
Q

What is the normal pao2 of air?

A

160 = (760 x .21)

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11
Q

If a patient on room air has a pao2 lower than 160, what does this indicate?

A

Air bubble

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12
Q

What happens to co2 when you have an air bubble since air contains no co2?

A

Co2 level in blood will fall and ph will rise

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13
Q

How long do samples last?

A

On ice- up to 1 hour

Not iced- only minutes

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14
Q

What happens when a sample is not placed on ice?

A

Blood cells metabolize, altering gas values and decreasing pao2 dramatically

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15
Q

When is the only time the pao2 will fall even if it is on ice?

A

If WBC>100,000 (leukemia)

16
Q

What should the temperature always be corrected to?

A

37

17
Q

What happens to the pao2 and paco2 if the patient is febrile?

A

Will be lower

18
Q

What happens to the pao2 and paco2 if the patient is hypothermic?

A

Will be higher

19
Q

How much will the pao2 and paco2 change for each degree above/below 37?

A

Pao2- changes 5mmhg

Paco2- changes 2 mmHg

20
Q

What are critical ph values?

A

7.55

21
Q

What are critical paco2 values?

A

70

22
Q

What is a critical pao2 value?

A

<55

23
Q

What is a critical sao2 value?

A

<85%