Heparin Drips And Lab Draws

Specializes in Critical Care/Vascular Access.

I've had the conversation with 2 or 3 different pharmacists lately who have all agreed that it is unnecessary to pause a heparin drip for 10 or 15 minutes before drawing a ptt, yet I still see nurses doing it.

Does anyone still do this and if so, why?

A 15 minute stop in the heparin is also enough to potentially alter the ptt, so you'd be adjusting the drip to an inaccurate result.

Even if you're drawing from a PICC/central line where the heparin is running, pausing the drip and using a thorough flush is still sufficient.

I'm just wondering how this little habit got so widespread without evidence prompting it, or is it just around the facility I'm at?

Heparin Drips

12 Answers

Specializes in Vascular Access.

Infusion Nurses Society standards state that an infusion, should be STOPPED prior to drawing labs for at least TWO minutes. Many IV pumps, when put on hold, will beep after two minutes, so that might help.

Also, it isn't best practice to draw coag studies from a lumen that has had Heparin drip, or locking solution in it. A peripheral VP is best. One study showed that if you must draw from said lumen, a 25 cc of waste should be obtained, for accurate results.

This stems directly from lab; not nursing. It's nice that the pharmacists in this particular scenario agree it isn't a necessary part of the process of adjusting the heparin gtt - - but what does lab say about the process of getting the sample they will use?

In some places they have quite a history of adamant statements about how we can't draw anything off any line (including a saline line) unless it's been locked for 15'.

Specializes in ACNP-BC, Adult Critical Care, Cardiology.

Sounds like a unit project you can work on to educate other nurses and even write a formal policy for your hospital with Pharmacy’s help.

Specializes in New Critical care NP, Critical care, Med-surg, LTC.

If nursing is drawing off a central line we just pause the line, flush, draw off a discard tube and then draw the sample. When lab comes in they usually just have us pause the drip if they have to draw on the same side as the IV. Otherwise it keeps running.

Specializes in anesthesiology.
On 1/17/2019 at 9:45 AM, Spadeforce said:

Do you know how quickly blood flows through the body. Wound answer your question.

cardiac output, basically your whole blood volume in one minute. We typically wait 3 minutes during cardiac surgery after a large bolus of heparin (like 30k units) before drawing an ACT, but this is after one single bolus dose. If you already have a drip running for a while you should be at steady state and not have to wait any time. You just don't want to be pulling heparin from the bag as you are drawing your sample.

Specializes in ICU and Dialysis.

There's a lot of superstition over these types of things. I will say, I've drawn a ptt from a heparin line, as well as a BMP from a TPN line. Never had unexpected levels, which would have been obvious with the BMP.

If it's a central line, all you need to do is flush really well and draw an adequate waste. The blood is coming basically straight from the heart. All you gotta do is wait like, 5 seconds and whatever was running in will be more than cleared out.

Do you know how quickly blood flows through the body. Wound answer your question.

Specializes in oncology, MS/tele/stepdown.

DUDES LET ME TELL YOU. Long story short, last night I was handed off a patient who was ordered a heparin gtt. She had a triple lumen central line with two available lumens. The dayshift RN didn't think we could run the heparin in one and draw the labs from the other, so he tried to get a peripheral (so the patient wouldn't get stuck multiple times for labs until therapeutic), but when that failed, the whole thing was deferred until the next dayshift with MD approval.

So she got stuck multiple times anyway for the PIV they couldn't get, the heparin gtt was never started, and that dayshift nurse refused to take her back the next day so it became a new nurse's problem. Like... what?

Specializes in Critical Care/Vascular Access.
On 1/17/2019 at 9:45 AM, Spadeforce said:

Do you know how quickly blood flows through the body. Wound answer your question.

My question was more or less rhetorical, but yes I do understand how quickly the blood flows through the body which is part of why waiting 15 min to draw a lab is ridiculous.

Specializes in Critical care.
On 1/16/2019 at 9:22 AM, Night__Owl said:

If it's a central line, all you need to do is flush really well and draw an adequate waste. The blood is coming basically straight from the heart. All you gotta do is wait like, 5 seconds and whatever was running in will be more than cleared out.

I have to disagree. I came in one morning and the night shift nurse couldn’t figure out why the patient’s labs came back so out of whack twice. I took over and said I’d figure it out. I walk in to do it and it’s dawned on me- the TPN wasn’t paused. I paused it and drew the BMP which then came back normal. Even with wasting if the TPN isn’t paused it will cause issues in my experience.

Specializes in anesthesiology.

Nurses always want a protocol for something so they don't have to think. Also to cover their ***. That way someone can't come behind them and get them in trouble b/c they "followed the protocol". Even if it is stupid.

Specializes in ICU and Dialysis.
On 1/19/2019 at 11:17 AM, AceOfHearts<3 said:

I have to disagree. I came in one morning and the night shift nurse couldn’t figure out why the patient’s labs came back so out of whack twice. I took over and said I’d figure it out. I walk in to do it and it’s dawned on me- the TPN wasn’t paused. I paused it and drew the BMP which then came back normal. Even with wasting if the TPN isn’t paused it will cause issues in my experience.

Sorry, I suppose I wasn't clear. I meant that all you had to do was pause whatever was running in for a few seconds, flush adequately and draw a waste tube. I wouldn't draw blood without pausing everything running into the lumens. But I've never had an out of whack result, and I don't pause for 15 minutes. I pretty much just bring in my supplies, pause the pump while I'm preparing my stuff, and then draw as soon as I have everything opened and laid out. So it may be paused for like, a minute and a half before I physically draw the blood out. The only time I ever got a bad draw was when I oopsed and forgot to pause the TPN at all, so it was running in one lumen as I was drawing out of the other. Maybe that's what happened to the nurse you followed.

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