air bubble in syringe

scrmblr · Apr 21, 2006

I think it is supposed to "bubble lock" the medication in the muscle after the injection. (the med goes in and then the "bubble" to "lock" it) It has never made much sense to me...

meownsmile, BSN, RN · Apr 21, 2006

Sure it does make sense. If medication is measured correctly the dose includes that in the needle too. So if you use a bubble it also ensures the accurate dose is being administered.

Consider Dilaudid, If you have to give a 0.5 mg dose and all you have is a 4mg carpuject to administer from your dose would be 2.5ml. Normally people use a 4ml syringe (although it doesnt really matter, same principle applies to a smaller measure needle) to draw the medication because of the needle length and guage. If you dont use an air bubble there would be medication left in the needle and at that small a dose it is important they get all of the medication and not leave 0.2 or so in the needle after injection. Yes you could draw some NS to expand the volume after you measure the dose, but then how much of the medication are you leaving in the needle?

Especially with pediatrics, its very important to make sure you are exacting with dosages.

ParrotHeadRN · Apr 21, 2006

Now see, I thought that syringes did NOT include what is in the needle as part of the dose. What about different sized needles, as well as drawing meds up with a blunt needle and then discarding the needle for IV administration?

TazziRN, RN · Apr 21, 2006

When you draw up and change the needle, before removing the needle you draw up a bit of air to clear the needle. You then remove the needle and change it. It's even safe to use that extra bit of air for an IVP med if you give it farther up the line, because the air will filter into the port tail. You wait a few seconds then withdraw that little bit of air with the same syringe (don't remove the needle from the port yet) and voila!

colleennurse, ASN, RN · Apr 21, 2006

Ok I am confused, do you inject the bubble into the person and is this for IM only? Sorry I am a student and I am just trying to understand :)

Zachary2011 · Apr 21, 2006

You can inject a small amount or air with all IM injections so that the air aids in pushing the med deeper into the muscle so less if any is lost when you remove the needle. As far as measuring whats in the needle, I hope one would change the needle from the one used to draw up to the one used for injection, and as someone posted the needles do hold meds..... ie; if you use a blunt to draw up morphine, say 2 mg which is 0.2 ccs then you pull back on the syringe after discarding the vial you will get about 1/2 cc or more of morphine that was in the blunt. making your dose almost 3 mg instead of 2 mg....... just change the needles from the one used to draw up the med to the one used for injection. Either way with the excpetion of pediatrics I wouldn't be to concerned.

Little Panda RN, ASN, RN · Apr 21, 2006

Okay I am also confused. I was taught in nursing school that the air bubble in the lovenox was to keep the medication locked into the subq tissue to help prevent bruising. I have never heard of a bubble being injected into muscle. Maybe someone on this board could help to clarify this issue.

beesnest · Apr 21, 2006

The measurement of the med is what is in the syringe- not what is in the needle too. Otherwise you would have differing doses based on what needle was used to draw up the med, and whether you changed the needle or not. Imagine drawing up something thick like Ativan with an 18G then changing the needle. Or drawing up an oral med like digoxin for a pedi patient and the removing the needle altogether. For a baby that could be half the dose in the needle...

The only constant the syringe companies have is their own syringe- so they can't take into account the needle you put on- they don't know what you are using. I was taught in nursing school to use the air bubble to make sure all the med had left the syringe- and the air filled the dead space in the needle.

TazziRN, RN · Apr 21, 2006

Okay I am also confused. I was taught in nursing school that the air bubble in the lovenox was to keep the medication locked into the subq tissue to help prevent bruising. I have never heard of a bubble being injected into muscle. Maybe someone on this board could help to clarify this issue.

You most certainly can inject an air bubble with IM's, it's called an air lock. When I give IM's I z-track and use air locks to minimize any leakage.

sweetpooty · Apr 22, 2006

Man, this issue goes on and on.

A syringe is made to give the correct dose that is marked with what is in the needle. If you think about it the plunger would stop and the needle would still be full. Therefore changing the needle is not a great idea and you would lose some.

Lovenox has a bubble that is to follow in the injection to keep the solution in the sub-q tissue and prevent bruising.

A bubble in a IM injection is also to keep the medication in the muscle and not the subq tissue. The bubble also needs to be behind the medication.

One of my biggest irks is a nurse who doesn't give any insulin that is 2units or less because it isn't even enough to get through the syringe. They act as though it's an unwrittten law.

As a diabetic I can tell you that those 2 units do get through and they do make a big difference for some. 2 units will drop my blood sugar 200 pts. So don't skip the insulin!

ParrotHeadRN · Apr 22, 2006

Man, this issue goes on and on.
As a diabetic I can tell you that those 2 units do get through and they do make a big difference for some. 2 units will drop my blood sugar 200 pts. So don't skip the insulin!

WOW, thanks so much sweetpooty (I feel a little dirty writing that LOL). I have always heard that about insulin. It's great to hear that from a nurse AND a diabetic!