A really silly question about drawing up meds in a syringe

Re: A really silly question about drawing up meds in a syringe

Thomas Johnson — Tue, 10 Jul 2012 11:59:18 GMT

If I'm giving a pre-med to a 15kg dog, for example, I draw 1ml of Vetergesic into a 2ml syringe, so I probably have 2.05ml, draw in some air and take off the needle. I draw 0.03ml of calmivet into a 1ml syringe, then inject it through the hub of the 2ml syringe, and mix thoroughly. I then put a fresh needle on the 2ml syringe, express all of the air, then inject the patient. The patient therefore gets 0.029ml of Calmivet and 2.001ml Vetergesic.

Re: A really silly question about drawing up meds in a syringe

Aurelijus vet — Sun, 08 Jul 2012 19:20:59 GMT

Re: A really silly question about drawing up meds in a syringe

plantagenet — Sun, 08 Jul 2012 17:38:42 GMT

[quote user="robloxley"]ACP 2mg/ml is back on the market [/quote]

It is? oh good, just timed by the skin of my teeth!

Is it back with all suppliers? why did it ever go away?

Re: A really silly question about drawing up meds in a syringe

Rob Loxley — Sun, 08 Jul 2012 12:00:37 GMT

Millpledge do a low dead space 1ml syringe
I'd use a 0.5ml insulin syringe (with almost zero dead space) to draw up the Calmivet. If your opiod takes you over 0.5ml then give separately
ACP 2mg/ml is back on the market

Re: A really silly question about drawing up meds in a syringe

Evelyn Barbour-Hill — Sat, 07 Jul 2012 12:39:58 GMT

[quote user="Michael Woodhouse"]

[quote user="Evelyn Barbour-Hill"]

[quote user="James Allsop"]IMHO this only tends to be a problem when drawing up multiple doses in the same syringe with the same needle - such as triple (DTK).[/quote]

Jeepers, you do that?

[/quote]

How would you do it? 3 syringes?

IIRC even the data sheet says can be mixed.

[/quote]

Draw the three drugs into three different syringes. Make space in one of them and put the other two drugs into it through the hub. Put fresh needle on (of course) and inject into patient. Incorporate air if you wish to "empty" the hub and needle.

If you habitually stick the same needle on the same syringe into three successive drugs, by the time you are nearing the ends of the bottles each of them will contain traces of the others.

I don't want to be obsessed by this.

But I am.

Re: A really silly question about drawing up meds in a syringe

Martin Atkinson — Sat, 07 Jul 2012 11:06:37 GMT

When you think about it all components of a multi-combination cocktail drawn in one syringe will overdose: all but the last will have the bit in the hub and needle drawn in and even the last one the bit left in the hub/needle will be pushed out by the others, and if left like that would actually over-dose more than the others because they now mixed and a mixture will be left in the hub. I sometimes therefore draw it all into the syringe with an air space mix the contents up, expel the air and inject, that way each component is only overdosing in proportion to the number of drugs in there. However, I feel we are all getting a bit too anal about this, in reality there is a good safety margin and, as said, I've never had a problem even in small furries.

Re: A really silly question about drawing up meds in a syringe

Michael Woodhouse — Sat, 07 Jul 2012 00:34:45 GMT

[quote user="Evelyn Barbour-Hill"]

[quote user="James Allsop"]IMHO this only tends to be a problem when drawing up multiple doses in the same syringe with the same needle - such as triple (DTK).[/quote]

Jeepers, you do that?

[/quote]

How would you do it? 3 syringes?

IIRC even the data sheet says can be mixed.

(I always do ketamine first as the injection only stings at the end)

Re: A really silly question about drawing up meds in a syringe

Kishor Mahind — Fri, 06 Jul 2012 21:50:01 GMT

[quote user="Evelyn Barbour-Hill"]

[quote user="Kishor Mahind"]Yesterday my nurse decided to put a multiple withdrawal spike on the Calmivet bottle.[/quote]

Sorry, irrelevant to your query, but:

the nurse decides things like that?

[/quote] She put the spike on the vial and then we came to know about it! No point in removing it now :-(

Re: A really silly question about drawing up meds in a syringe

Evelyn Barbour-Hill — Fri, 06 Jul 2012 21:12:02 GMT

[quote user="Kishor Mahind"]Yesterday my nurse decided to put a multiple withdrawal spike on the Calmivet bottle.[/quote]

Sorry, irrelevant to your query, but:

the nurse decides things like that?

Re: A really silly question about drawing up meds in a syringe

David Mills — Fri, 06 Jul 2012 19:24:13 GMT

[quote user="Kishor Mahind"]I would sound really silly asking this question but this tiny thing is bothering me since yesterday. Until yesterday we used a hypodermic needle attached to 1ml syringe to draw up various meds including Calmivet. So we will draw up the required dose upto the graduations on the syringe, say if dose is 0.12ml then we would draw upto 0.12 mark on syringe and that included the drug left in the needle and its hub (which I think was the right thing to do as I was taught this way in the university). I've calculated the volume which a 23G 5/8" needle will hold is about 0.05ml. After drawing, to change the needle we will draw back all the drug that's in the needle into the syringe and then attach a new needle. Yesterday my nurse decided to put a multiple withdrawal spike on the Calmivet bottle. So now we are attaching the syringe directly to the spike and drawing up Calmivet upto the required graduation on the syringe. Does it mean I'm drawing up 0.05ml less?

[/quote]

Yes. You should draw up a small amount more as this will be left in the hub of the needle. Needle and syringes are designed to include the amount in the barrel plus hub and takes into account the stuff 'left over'. For this reason the moan above above waste is null because some is always 'wasted' in the needle anyway. Insulin syringes are the same but just waste less (but cost more). This is the reason for the sketch of a doctor squirting a little out of the syringe- when changing needle it is advisable to draw back a little bit more to air, change syringe, then squirt a little out until the gradation is met. Estimates vary on the amount left in the hub from 0.01-0.05ml.

Re: A really silly question about drawing up meds in a syringe

Evelyn Barbour-Hill — Fri, 06 Jul 2012 17:57:11 GMT

[quote user="James Allsop"]IMHO this only tends to be a problem when drawing up multiple doses in the same syringe with the same needle - such as triple (DTK).[/quote]

Jeepers, you do that?

Re: A really silly question about drawing up meds in a syringe

Mark Hedberg — Fri, 06 Jul 2012 15:53:42 GMT

I draw up the ketamine first, then the medetomidine, then the butorphanol, as I find the torb is injected first, 'cushioning' the ket and medet, and causing less stinging. Maybe it's just me but I do tend to notice a difference.

Re: A really silly question about drawing up meds in a syringe

James Allsop — Fri, 06 Jul 2012 15:44:51 GMT

IMHO this only tends to be a problem when drawing up multiple doses in the same syringe with the same needle - such as triple (DTK). I was taught to draw up the torm first as an extra 0.05ml into the combination would be insignificant whereas an extra 0.05 of domitor may be more problematic for smaller patients. The standard dose of torb on the charts for DTK are noramlly 0.1mg/kg (compared to 0.4mg/kg for analgesia). You will of course end up with a very slight underdose of the drugs as a small quantity of all 3 will be left in the hub.

Re: A really silly question about drawing up meds in a syringe

Andrew Kent — Fri, 06 Jul 2012 14:41:03 GMT

You also lose the residual volume in the hub after injection meaning then that you underdose all patients whereas if you draw up in the syringe that volume is factored in?! I like insulin syringes for accurate dosing but can see no benefit in using them for what you describe!

Re: A really silly question about drawing up meds in a syringe

Rajat — Fri, 06 Jul 2012 11:56:38 GMT

Well volume is lost but it is a known value i.e draw up .2ml morphine into a syringe containing 0.02ml calmivet. There will be some morphine loss in the hub but the 0.22ml is delivered to the patient. Accuracy of dosing remains present..however pulling up calmivet via a syringe, then pulling up morphine in the same syringe means the calmivet from hub will mix with morphine if same needle is used ...but if the needle is changed without withdrawing hub contents of calmivet into syringe then accuracy remains but wasteage of the 'hub' volume of calmivet from the needle disposed of occurs for every dose along with aforementioned morphine loss...

I think I am close to confusing myself now, its is a Friday..!

Re: A really silly question about drawing up meds in a syringe

Andrew Kent — Fri, 06 Jul 2012 11:49:12 GMT

But in terms of volume lost in hub you lose all benefit of using an insulin syringe by putting it into any other syringe regardless of how many drugs it is mixed with.

Re: A really silly question about drawing up meds in a syringe

Rajat — Fri, 06 Jul 2012 11:22:00 GMT

It's just one other drug - so acp (calmivet ) drawn up from insulin syringe and squirt into 1-2ml syringe before pulling up morphine/buprenorphine into this syringe and injecting ...

I can see your logic though - wouldn't work for more than 2 drugs

For triple combos I would pull up drugs separately in insulin syringe then combine (esp as often for bunnies, small cats etc even a small OD can be significant!)

Re: A really silly question about drawing up meds in a syringe

Andrew Kent — Fri, 06 Jul 2012 11:15:10 GMT

[quote user="Martin Atkinson"]

[quote user="Rajat"]We use insulin syringes for this purpose- draw up calmivet with insulin syringe and other drugs with 1-2ml syringe. squirt calmivet into the other syringe prior to pulling up additional drugs. [/quote] I can't quite see the logic of this unless you apply it all the components of a multi-drug combination - the amount of the second and subsequent drugs except the last one drawn that are still in the needle and hub will then be drawn into the syringe so still effectively over-dosing. Should we always reduce the dose of all but the last drawn drug to compensate? I don't and never knowingly have had a problem but with tiny doses in small mammals this could be an issue

[/quote] I was thinking the same thing - surely there is only a benefit in drawing up in insulin syringe if going to inject with it - otherwise you have exactly the same problem of residual drug in hub (though of course this may only be a small proportion of the drug if mixed with larger volumes of something else.)

Re: A really silly question about drawing up meds in a syringe

Martin Atkinson — Fri, 06 Jul 2012 10:58:30 GMT

Re: A really silly question about drawing up meds in a syringe

Rajat — Fri, 06 Jul 2012 10:38:52 GMT

[quote user="Kishor Mahind"]So now we are attaching the syringe directly to the spike and drawing up Calmivet upto the required graduation on the syringe. Does it mean I'm drawing up 0.05ml less?[/quote]

Yes you will have some residual in the hub as others pointed out so when you inject thru the new needle (with an empty hub) there will be this amount left in there (0.05-0.06mls..)

We use insulin syringes for this purpose- draw up calmivet with insulin syringe and other drugs with 1-2ml syringe. squirt calmivet into the other syringe prior to pulling up additional drugs.

Pulling up more than required then discarding seems wasteful possibly risks accuracy especially with calmivet as quite concentrated but the insulin needle is a pain in the a** too - fiddly and takes more time!

Re: A really silly question about drawing up meds in a syringe

Mark Hedberg — Fri, 06 Jul 2012 09:39:11 GMT

I had actually heard it was 0.06ml that was in the hub; however I understood that this was over and above the indicated amount in the syringe. (I'm quite happy to be wrong, I didn't do any calculations, just heard it at a CPD lecture once.)

I cheerfully admit your method is more scientific and probably more accurate than my "I heard it once" story!

Re: A really silly question about drawing up meds in a syringe

Jo Cobbett — Fri, 06 Jul 2012 09:37:30 GMT

My thought would be yes - when you then attach a needle and fill the needle hub, the plunger will no longer be in the 0.12ml position, but at approx 0.07ml.

One of the branches I've worked at have just started using the same system, the nurses draw up slightly more Calmivet that needed, attach the needle, then ensure the dose is correct, which normally involves expelling (and wasting) a small amount of the calmivet.