can ABG be taken from a CVC?

Question

Could an Arterial Blood Gas Sample be taken from a Central Venous Catheter?
or from any catheter that enters the pulmonary artery?

Answer 1

An ABG is usally drawn from an artery. They are commonly drawn from arterial lines. If we are desperate, and have trouble drawing from an artery, then YES we do perform venous ABGs. You must alter your normal values though to account for the different composition of venous blood. If you are taking a venous ABG then you could use a CVC.

Answer 2

By definition, an ABG must come from an artery. A sample drawn from a central venous catheter is a mixed venous sample, not an arterial sample. It has different normal ranges and what those numbers are mean different things. For example, the PaO2 on an ABG and a PvO2 from a central catheter do NOT mean the same thing. The PaO2 reflects oxygenation; the PvO2 reflects cardiac output. You can't judge oxygenation from a venous gas because it is very heavily influenced by the cardiac output. Similarly, the venous CO2 doesn't tell you as much about ventilation.

Beyond all of that, any VBG that didn't come from a central catheter is totally useless. You see them drawn, but clinically they are totally irrelevant (and in fact, I regularly had to reject gases sent to me because they were peripheral venous gases. That is not a valid test and ethically I cannot report a value if I know you are going to treat based on that value. I cannot knowingly give you invalid information if I know you are going to use that information to make a clinical decision.). If you think about the anatomy of veins versus arteries it should be apparent why that is.

Answer 3

No. ABG has to be tested with arterial blood. CVC will give you MIXED venous blood thus you could test a VENOUS BLOOD GASES which is also used to determine the acid-base balance status in patients with critical hemodynamic compromise.

Answer 4

No. You've actually answered your own question. Because the CVC is venous, you can never get an ABG from it.

ABG's are drawn from the small arties in your wrist.

Answer 5

the pulmonary artery carries venous blood to the lungs, so you cannot draw arterial samples from this line...