Multiple lab draws off IV periph line, tourniquet timing

NurseStorm, BSN, RN · Mar 16, 2016

In my experience it would be difficult to get 20 tubes off a peripheral line. I find the flow will start to slow eventually, even with tourniquet and having arm dangling down (so gravity can assist), and you may end up ruining your line. If you are going to be drawing that many tubes I would try to go for the largest gauge possible that is appropriate, so possibly an 18g, or at the minimum a 20g? I do a lot of peds so I know a 24 or 22 would have poor chance to withstand 20 tubes drawn at a time.

I have successfully drawn about 4-6 tubes every 2 hrs before, with 1-2 tubes on the opposite hour from a 22g before with no issues. This is mostly anecdotal from experience and not based on official research (Unless you meant to say central line since you are talking about oncology patients, which most will have a central line of some sort typically, in which case ignore my first info)

Also, I'm assuming you will get a much more effective flow without the saline lock on.. if you do blood draw at the very start after inserting peripheral line this may work, but if they already have the line and saline lock in place and blood work is intermittent, removing the saline lock may be a hassle/risky for losing the IV... depending on your population and how hard of a poke they are this risk may be not worth it.

*edit* I do not do oncology btw. My technique is to dangle the limb off the bed, then apply a tourniquet while keeping the limb dangling with gravity while having my tubes lined up in proper order. If there is a saline lock, I make sure to remove the tape or retape in such a way that the tubing will be basically a straight line with gravity down towards the floor, to ease the flow (rather than taped around the hand and up the arm if that makes sense? I will untape that and basically just let the saline lock dangle straight down during the draw). I keep the tourniquet on while drawing. I don't know the official timing of what is allowed but I wouldn't leave it on longer than a minute personally.

Nerd eNurse, ADN · Mar 16, 2016

Sujule,

I am a critical care nurse/inventor. Proper lab collection is something that I am very familiar with because I had to research it for an invention that I developed. Your question is a good one. The one minute rule is very important. Here is a link to an article that Dennis Ernst an expert in phelbotomy wrote on the subject: click on this link tourniquet.

Your question reinforces my view that nurses are not trained properly on how to collect blood according to the CLSI(Clinical & Laboratory Science Institute). Tourniquet time is a variable in the blood collection process. It is called a preanalytical variable. From a nurses point of view, a preanalytical variable if any variable from the time we start collecting the blood to the time it is received by the lab. A few other major ones that most of us have never heard of are: "Order of Draw", the right number of inversion for each type of vacuum tube, overfilling blood culture tubes can give false negatives, etc. There are also many other variables not found in the standards because the CLSI standards only address venipuncture and not drawing off of lines. One that I found interesting is that there is a suggested maximum amount of blood that should be drawn per day.

I hope to change the culture of how we are educated for lab drawing. Every hospital needs to make proper lab drawing part of the core educational program for all nurses that draw blood. Nurses need to represented on the standards committee.

Sujule · Mar 16, 2016

Thank so much for the feedback, NurseStorm and Gaitor. Both of you had great comments. My first post and I'm so grateful. My thoughts and take away:

The blood will be drawn right after the line is placed so the saline lock is not an issue.

I have an "Order of Draw" dictated by the protocol.

I requested oncology research nurses only because I know they draw lots of blood; however, the both of you gave me a more than enough.

The article regarding the tourniquet was very valuable.

I completely agree more training for nurses regarding this particular skill. I've been a nurse for over 35 yrs and finding information on topics like this is very difficult. So happy to have found this site.

My plan is to place the line, using either a 20g or 22g(if appropriate) and secure. Dangle the arm, apply the tourniquet, utilize a timer and draw as many tubes as possible within the minute. Release the tourniquet, place the pts arm on the arm rest, and wait 2 - 3 minutes. Repeat the process.

Thank you again, you were extremely helpful!

bgxyrnf, MSN, RN · Mar 16, 2016

If you're going to be drawing 20 tubes, I'd be certain how much blood you actually need to perform your assays. For example, by default we draw about 4mL for a set of basic chemistry and belly labs but those same labs can be run off of a pedi tube with 0.8 mL.

If you're drawing from an existing PIV, you may have more success using a syringe to draw, especially if it's a 3cc one, though you have to be careful in your technique not to hemolyze the specimen. It's helpful to have somebody next to you to hand over the syringe to in order to minimize the draw duration and the time-to-tube.

Anecdotally, bigger bore catheters aren't always better for draws. In fact, 16's seem to present more difficulty delayed draws than do 22's.

Another thing to consider is using a bp cuff, especially if you have a machine that has a venipuncture setting, because the occlusion is much more uniform, repeatable, and spread out over a much larger area.

Sujule · Mar 18, 2016

Thank you Kindaback.

The amounts needed have been specified in my research protocol. It will not be an existing line. The gauge will be 20/22 depending. I have used a bp cuff and I'm considering using it for this project. I like the idea of having some control over the pressure and the ability to release and re-inflate with ease.

This is my first time posting and the responses and info have been awesome. Thank you all again.

Nerd eNurse, ADN · Mar 22, 2016

The amounts needed have been specified in my research protocol.

One thing to consider if you haven't already is how much blood you are drawing per patient per/kg/draw. Here is a link.

One of my favorite sites that is a wealth of knowledge is: Center for Phlebotomy

I like the blood pressure cuff it will give you better control of the project. One less variable to account for. It is kinda hard to account for the technique used for tightening a tourniquet. I believe the maximum recommended cuff pressure for blood drawing is 20 points above the diastolic. You can probably find at at the link above. Best Wishes!

Sujule · Mar 23, 2016

Thank you Gaitor. There are a couple of schools of thoughts regarding the bp cuff. 1) Inflate the cuff to 20 mm below the diastolic or 2) Pump the cuff to 30 - 40 mmHg. or 3) Pump the cuff to just below the pt's diastolic. I find pumping 20 mm Hg below diastolic falls around the 30 - 40 mark and usually use that case. In all cases, taking care not to place the cuff too close to the IV site.

Thank you for the links and all your assistance.