Drawing blood through a Saline Lock??

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I recently started a new job - which I LOOOVE, and am so much happier at, but the other day, I had a pt who was upset that the lab was coming to "stick her" when a nurse on another floor drew her blood through her saline lock, and told her she wouldn't have to be stuck anymore because we could just draw blood that way. The woman came in with bilateral PE's and needed a PT/INR drawn, plus and CBC and CMP. I've never heard of drawing blood through a saline lock before and couldn't get blood return anyway through any of them (she had 2) even though they flushed fine. Am I off track here - I don't think it's a good idea to do this. :no:

For non central lines, plain ol heplocks/saline locks, etc I've been told that when you first start the line, and the tourniquet is still in place you can, but after that, no can do.

Wow...we would have a riot if they told us that, lol. :monkeydance:

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I think risk of hemolysis depends a lot on the size of catheter and vein. I very rarely get hemolysis with #20 or larger, in an AC or forearm...vs more common hemolysis with a #22 in a hand. And I've never lost an IV site from drawing blood off of it. We use a positive pressure flushing technique, which probably helps.

:yeahthat: :yeahthat:

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Specializes in ICU, Research, Corrections.
I think risk of hemolysis depends a lot on the size of catheter and vein. I very rarely get hemolysis with #20 or larger, in an AC or forearm...vs more common hemolysis with a #22 in a hand. And I've never lost an IV site from drawing blood off of it. We use a positive pressure flushing technique, which probably helps.

I do it all the time in the ICU setting with an 18 gauge IV. Rarely do I have a hemolysis problem.

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Specializes in Flight, ER, Transport, ICU/Critical Care.

Short Answer - IT DEPENDS!

Longer Answer - I always do (or at least try) when placing an IV "draw" initial labs off the catheter. (I will not, however, risk a loss of the IV to get labs in the case where the blood return at the site is difficult - very rare event). I have very few specimens rejected due to hemolysis, so I think I'm doing things right! I estimate I've done IV's in the thousands and can count on one hand the # of specimens I've had rejected.

Explanation: I place at least at 20 gauge in the AC (I know, bad spot but more often than not - clinically indicated in the ED setting for a variety of reasons) and then attach a multi-sample device directly to the IV catheter and draw the tubes. (Always starting with a plain red top and then the blue to ensure the highest accuracy of coag studies, then proceed via policy with the remaining tubes). Remove the multi-sample adapter & then attach an extension set that is primed for flushing to the catheter, place a sterile securing dressing over the site. I then flush the line and secure/label the site.

I have also used a syringe(s) for drawing and transfered blood to the tubes using a blood transfer device. Either is acceptable and fairly straightforward.

Just be sure to obscure the blood flow with manual pressure on the vein above the puncture site at area where the IV cath sits in the vein - or you will be cleaning up some of that free flowing blood!

Now to the need to draw from an EXISTING IV catheter site that is saline "locked". Few places have formal policies on this, so...

But, YES, I do it on occasions. The procedure I follow is this:

1. The site MUST be a lock.

2. There can be NO infusions going in a different site in the same extremity. (Example: IV lock with 18 gauge in the Right AC with NS/Heparin infusing in 2nd site in the Right wrist - I know some will argue about the distal/proximal site thing, but why take a chance! Same extremity = not going to do it)

3. I flush with the lock/extension with 3 - 5 ml of saline.

4. Apply a tourniquet above the site. Open the lock adapter.

5. Ensuring that the open extension remains sterile, remove the injecting adapter and draw a waste of a minimum of 10 ml. Discard to prevent a mix-up. **You can draw via syringe or multi-sample adapter with any tubes - just be certain that you use a new syringe/multi-sample adapter for the actual "sample".**

6. Close the lock adapter.

7. Remove the tourniquet and wait 2 - 3 minutes.

8. Apply the tourniquet, open lock adapter and then draw 3 ml of additional waste and proceed to collect your sample(s).

9. Close the lock adapter, remove the tourniquet.

10. Replace with new, sterile injecting adapter and saline flush with 10 ml.

I have found that 20/18 or larger IV catheters that are saline locked in the AC sites tend to be fairly easy places to access for serial blood samples. If it does not risk the site (I've never lost a site from a lab draw, but I know that others have) and the process can be completed with a cooperative patient I think it benefits the patient. It does, however, require a clinician to be very exact.

Good Luck! ;)

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