The Student Room Group

Help performing a venous blood gas

Hi! I’m a final year medical student and am having trouble working out how to perform a venous blood gas. I’ve been shown and know how to do an ABG but I’m a bit confused about VBGs. My understanding currently is that you draw venous blood like normal from a needle and a normal syringe. Do you then transfer the blood from the normal syringe to an ABG syringe? If so, how do you do that? The transferring of the blood from one syringe to the next is what is really confusing me, and I can’t see any videos on YouTube to help! Also, can you use a butterfly needle to attach to the initial syringe you draw blood with? I find butterflies so much easier than the other needles!

If someone could help me I’d be greatly appreciative! Thank you!
Original post by bex1995
Hi! I’m a final year medical student and am having trouble working out how to perform a venous blood gas. I’ve been shown and know how to do an ABG but I’m a bit confused about VBGs. My understanding currently is that you draw venous blood like normal from a needle and a normal syringe. Do you then transfer the blood from the normal syringe to an ABG syringe? If so, how do you do that? The transferring of the blood from one syringe to the next is what is really confusing me, and I can’t see any videos on YouTube to help! Also, can you use a butterfly needle to attach to the initial syringe you draw blood with? I find butterflies so much easier than the other needles!

If someone could help me I’d be greatly appreciative! Thank you!


I’ve always wondered the same thing tbh. As far as I know you take the top off the abg and just syringe in, expel any extra air and put the cap on.

Just FYI it is possible to get VBG syringes which you can just directly use. But this is probably trust and ward specific (generally only seen them in a&e and amu etc)
You take the top of the ABG syringe, fill it up and then put the lid back on
If you're only doing a VBG, just attach a blood gas syringe to the butterfly, and take blood as normal.

If you're doing normal bloods and VBG, then I'd normally just take blood in a 10ml syringe. Once I've filled the syringe, then you can just fill the bottles and gas syringe either using the same butterfly needle you took the blood with, or by attaching a fresh needle. To fill the gas syringe, just take off the cap, insert the needle in, and press down on the syringe containing the blood.
You can stick the VBG syringe onto the covered needle inside the vacutainer if you're taking other bloods first, you just have to hold it still and pull back on the syringe.
Original post by Becca-Sarah
You can stick the VBG syringe onto the covered needle inside the vacutainer if you're taking other bloods first, you just have to hold it still and pull back on the syringe.


Mind blown. Didn’t know you could do this. Will have to try this next time.
I am now thoroughly confused what you were all talking about :biggrin:

We use a butterfly or barrel needle (Exactly the same as normal phlebotomy) and attach a green vaccutainer (green bottle).
We then run the green vaccutainer directly through the ABG machine, but as a VBG.

There is no transferring of anything from one syringe to another syringe. I've seen this done at every hospital I've been placed at.

For an ABG, we just use an ABG Syringe (already fully assembled with needle/syringe in a sealed packet), collect the blood, detach the needle part into a sharps bin and run the sample through the ABG machine.

Am I missing something?
(edited 6 years ago)
Original post by Lionheartat20
I am now thoroughly confused what you were all talking about :biggrin:

We use a butterfly or barrel needle (Exactly the same as normal phlebotomy) and attach a green vaccutainer (green bottle).
We then run the green vaccutainer directly through the ABG machine, but as a VBG.

There is no transferring of anything from one syringe to another syringe. I've seen this done at every hospital I've been placed at.

For an ABG, we just use an ABG Syringe (already fully assembled with needle/syringe in a sealed packet), collect the blood, detach the needle part into a sharps bin and run the sample through the ABG machine.

Am I missing something?


ABG - stab ABG syringe/any syringe [with needle] in patient and collect blood. Put blood in ABG syringe, if not already, and run blood using ABG machine.
VBG - take blood in any way from any vein. Put blood in ABG syringe and run it using ABG machine.

I hate the small ABG syringes, so I usually use a 10ml syringe, get all the blood, then I take the top off the ABG syringe and fill it + use the rest of the blood to fill in other blood bottles to send off.
Original post by notespad
ABG - stab ABG syringe/any syringe [with needle] in patient and collect blood. Put blood in ABG syringe, if not already, and run blood using ABG machine.
VBG - take blood in any way from any vein. Put blood in ABG syringe and run it using ABG machine.

I hate the small ABG syringes, so I usually use a 10ml syringe, get all the blood, then I take the top off the ABG syringe and fill it + use the rest of the blood to fill in other blood bottles to send off.


But you don't need to use either an ABG Syringe or a standard syringe at all. You can use a specific blood bottle, whilst you collect all the other bloods:

Light blue bottle = Clotting
Yellow bottle = Biochemistry
Purple bottle = FBC etc
Green bottle = VBG (Just run the VBG straight away, not in 20 minutes time).

ABG syringes cost £££ relative to blood bottles, hence we certainly do not open an ABG needle&syringe to run a VBG.

I have literally never seen anybody use an ABG syringe at all - in any way - for a VBG. (I have seen quite a few as well :tongue: )
(edited 6 years ago)
Original post by Lionheartat20
But you don't need to use either an ABG Syringe or a standard syringe at all. You can use a specific blood bottle, whilst you collect all the other bloods:

Light blue bottle = Clotting
Yellow bottle = Biochemistry
Purple bottle = FBC etc
Green bottle = VBG (Just run the VBG straight away, not in 20 minutes time).

ABG syringes cost £££ relative to blood bottles, hence we certainly do not open an ABG needle&syringe to run a VBG.


Different hospitals/trusts have different equipment, and regardless, there is more than one way to take blood.
Original post by Chief Wiggum
Different hospitals/trusts have different equipment, and regardless, there is more than one way to take blood.


Very true there is more than one way to take blood!

I had presumed - wrongly - green blood bottles for VBGs were universal phlebotomy equipment available to the NHS. They are exactly the same as any other bottle, so it's just 1 more blood bottle to collect when you are already taking blood; without any need to transfer blood from one container to another container (which, to me, sounds like an unnecessary theoretical infection risk - albeit tiny, there are methods out there that make it unnecessary in this situation).

It'll be rather strange & interesting to find out how things vary across different Trusts when we move on - to how our Med School trust/area operates.
(edited 6 years ago)
Don’t think I’ve ever seen green bottles used for this. We use the ABG syringe in my trust for ABG or VBG. You can also use a capillary tube for paeds which can contain a venous or capillary sample or a micro sample in which case you need to select Micro on the machine and unselect values you don’t need
Reply 12
Original post by Lionheartat20
But you don't need to use either an ABG Syringe or a standard syringe at all. You can use a specific blood bottle, whilst you collect all the other bloods:

Light blue bottle = Clotting
Yellow bottle = Biochemistry
Purple bottle = FBC etc
Green bottle = VBG (Just run the VBG straight away, not in 20 minutes time).

ABG syringes cost £££ relative to blood bottles, hence we certainly do not open an ABG needle&syringe to run a VBG.

I have literally never seen anybody use an ABG syringe at all - in any way - for a VBG. (I have seen quite a few as well :tongue: )


Oh my gosh, I’m mind blown. I’ve never heard of using a green tube for vbg. Wish more places did this, as it makes it so much easier just to whack on another bottle.
Original post by Lionheartat20
Very true there is more than one way to take blood!

I had presumed - wrongly - green blood bottles for VBGs were universal phlebotomy equipment available to the NHS. They are exactly the same as any other bottle, so it's just 1 more blood bottle to collect when you are already taking blood; without any need to transfer blood from one container to another container (which, to me, sounds like an unnecessary theoretical infection risk - albeit tiny, there are methods out there that make it unnecessary in this situation).

It'll be rather strange & interesting to find out how things vary across different Trusts when we move on - to how our Med School trust/area operates.


I have never seen these. Everywhere I've worked (I think 8 different Trusts around London/SE) uses blood gas syringes for all blood gas measurements, regardless of vessel of origin. Wouldn't even know how to put a vacutainer onto our machines!
Original post by Helenia
I have never seen these. Everywhere I've worked (I think 8 different Trusts around London/SE) uses blood gas syringes for all blood gas measurements, regardless of vessel of origin. Wouldn't even know how to put a vacutainer onto our machines!


You just hold the blood bottle against the ABG machine inlet, start the machine, and then the tube comes out of the ABG machine until it makes contact with the blood in the bottle and then draws it up into the machine.
You do have to physically hold the blood bottle against the machine though (circa 20 seconds), unlike an ABG syringe which you don't have to hold in place with your hand.

I do actually take the green lid bit off the bottle so, on reflection, you are dealing with bodily fluids anyway. It just makes sense for me though that you can just stick a green bottle with all the other bloods you are taking, then you uncap the blood bottle (circa 1 second) at the ABG machine and run it there and then.

--

I've repeatedly been told by doctors that it's about the cost compared to their ABG syringe but I can't 100% say it's true, i've only heard it from them.

Anyways I'm glad this thread was made; I'd otherwise have been looking everywhere on my first day an F1 where the green bottles are :colondollar:
Original post by Lionheartat20
You just hold the blood bottle against the ABG machine inlet, start the machine, and then the tube comes out of the ABG machine until it makes contact with the blood in the bottle and then draws it up into the machine.
You do have to physically hold the blood bottle against the machine though (circa 20 seconds), unlike an ABG syringe which you don't have to hold in place with your hand.

I do actually take the green lid bit off the bottle so, on reflection, you are dealing with bodily fluids anyway. It just makes sense for me though that you can just stick a green bottle with all the other bloods you are taking, then you uncap the blood bottle (circa 1 second) at the ABG machine and run it there and then.

--

I've repeatedly been told by doctors that it's about the cost compared to their ABG syringe but I can't 100% say it's true, i've only heard it from them.

Anyways I'm glad this thread was made; I'd otherwise have been looking everywhere on my first day an F1 where the green bottles are :colondollar:

So you have to take the cap off the vacutainer and hover the open blood bottle up against the machine while it takes the sample? Literally never seen this, and I've worked in more places than most people here. Nobody has ever mentioned how much a blood gas syringe costs. Strange how practice varies even when you think you've seen it all!
Original post by Helenia
So you have to take the cap off the vacutainer and hover the open blood bottle up against the machine while it takes the sample? Literally never seen this, and I've worked in more places than most people here. Nobody has ever mentioned how much a blood gas syringe costs. Strange how practice varies even when you think you've seen it all!


I imagine you can leave the rubber cap on the vacutainer, the needle on the ABG machine should pierce the lid. Taking the lid off could be a bit messy I imagine.

I'm just guessing here, I've never seen a vacutainer being used on a gas machine.
Original post by Lionheartat20
ABG syringes cost £££ relative to blood bottles, hence we certainly do not open an ABG needle&syringe to run a VBG.


Lithium heparin vacutainers cost about 12p, and a blue butterfly needle costs about 60p. ABG syringes cost about £1.

I have worked in 1 trust where we used heparin vacutainers for VBGs. However, we would take it then syringe it up into an ABG syringe so we could attach it to the machine :p: It did mean it was easier though and meant that asking a nurse to take a VBG was absolutely fine, whereas in other trusts they'd say they were not qualified and make the doctors do it :mad:
Original post by moonkatt
I imagine you can leave the rubber cap on the vacutainer, the needle on the ABG machine should pierce the lid. Taking the lid off could be a bit messy I imagine.

I'm just guessing here, I've never seen a vacutainer being used on a gas machine.


I've actually always taken the lid off, but only as I've seen others do it and don't want to risk any damage to expensive equipment - just in case :tongue: I also presume the needle should go straight through the lid though.


Original post by nexttime
Lithium heparin vacutainers cost about 12p, and a blue butterfly needle costs about 60p. ABG syringes cost about £1.

I have worked in 1 trust where we used heparin vacutainers for VBGs. However, we would take it then syringe it up into an ABG syringe so we could attach it to the machine :p: It did mean it was easier though and meant that asking a nurse to take a VBG was absolutely fine, whereas in other trusts they'd say they were not qualified and make the doctors do it :mad:


Most of the time we take other bloods apart from the VBG, so I wouldn't count the 60p in the calculation. And I believe a butterfly needle is more expensive than a barrel, as we're encouraged to use a barrel first if appropriate for the vein / clinical situation.

If you actually were just to use the Lithium Heparin vaccutainer without opening the ABG packet (? Did they think that through :biggrin::biggrin: ? Most people stand at the machine whilst they wait for the printout anyway, so surely it's more effort to put it in an ABG syringe), there are pretty big savings to be made if your numbers are right and it was changed en-mass trust-wide; especially in high usage departments like A&E (12p versus a £1 for the ABG kit).
(edited 6 years ago)

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