Pitfalls Of ABGs Flashcards
What should the venous PvO2 usually be?
Less than 40 mmHg
What should you look for when performing an ABG?
Blood pulsating syringe
What should venous saturation be?
Less than 75%
What two things will be close to arterial values, making it hard to differeniate?
pH and pvo2
If the fio2 is changed, how long should it take normal patients to achieve a steady state?
3 minutes
If the fio2 is changed, how long should it take chronic obstructive patients to achieve a steady state?
20 minutes
What does heparin cause?
A drop in the paco2
When is heparin most frequently found in an ABG?
When the blood is drawn from an indwelling catheter
What kind of ph does heparin have?
Slightly acidic
What can offset the acidic ph of heparin?
Any rise in blood ph when paco2 false
What is the normal pao2 of air?
160 = (760 x .21)
If a patient on room air has a pao2 lower than 160, what does this indicate?
Air bubble
What happens to co2 when you have an air bubble since air contains no co2?
Co2 level in blood will fall and ph will rise
How long do samples last?
On ice- up to 1 hour
Not iced- only minutes
What happens when a sample is not placed on ice?
Blood cells metabolize, altering gas values and decreasing pao2 dramatically
When is the only time the pao2 will fall even if it is on ice?
If WBC>100,000 (leukemia)
What should the temperature always be corrected to?
37
What happens to the pao2 and paco2 if the patient is febrile?
Will be lower
What happens to the pao2 and paco2 if the patient is hypothermic?
Will be higher
How much will the pao2 and paco2 change for each degree above/below 37?
Pao2- changes 5mmhg
Paco2- changes 2 mmHg
What are critical ph values?
7.55
What are critical paco2 values?
70
What is a critical pao2 value?
<55
What is a critical sao2 value?
<85%
