Incision/Extraction Techniques

[Protimenow]

In another thread, Pellicle said something about the main source of difference (between test results) 'being incision/extraction techniques.'

With the exception of the Protime meters, all the meters require the first drop of blood, delivered to the strip within fifteen seconds of the incision.

This sounds pretty straightforward -- but may not really be all that straightforward.

The suggested technique usually involves warming the finger that will be used for the blood drop -- usually by washing or rinsing it in warm water, or by resting it on some kind of hand warmer. In order to get a good drop of blood, it's often recommended that you squeeze the finger below the knuckle so the fingertip fills with blood. So far, so good.

One forum member said that he has great success with a 'dental floss/thread' trick. This trick works well -- you wrap a piece of dental floss or thread around the finger two or three times. This will make the fingertip fill with blood. It works--maybe too well.

The meter manufacturers advise you not to 'milk' the finger -- trying to draw blood into the fingertip by squeezing the finger and moving the blood into the tip -- because it can add interstitial fluids that will change test results. I wonder if the 'dental floss' trick may also help to create a pool of the interstitial fluids that can throw the results off.

Personally, I seem to have more, consistent success using one-time-use 21 gauge lancets than I do with a lancing device and 21 gauge lancet.

I'm curious to see if any of you have encountered issues with 'improper' technique; or seen a lab or doctor's office do the incision extraction any differently from the way that you are doing it at home; or if you have anything to contribute about the proper (or improper) way to get a good, accurate, test result.

 

[pellicle]

When I started my values were as much as 0.7 away from the blood draws. After I learned of the 15second rule and perfected with a tourniquet (I found at I often just don't bleed well until after the extraction) extraction I got much closer results

 

[Protimenow]

The 'tourniquet' that you mention is the thread/floss thing. Right?

 

[CATDOG]

I have seen starter kits on the Internet selling the Coaguchek XS that say they come with a lancing device and capillary tubes. Is it ok to use those with any of the machines? I know some people here have written about using the tubes and having it make it easier to put the drop where they need it to go.

 

[Protimenow]

Capillary tubes can make it somewhat easier to draw the blood into the tube and then to deposit the drop onto the dot on the strip. These can be helpful with the InRatio. I've had mixed success using these transfer tubes with the InRatio, but certainly don't recommend AGAINST using them.

The CoaguChek XS makes it pretty easy to transfer the blood onto the strip -- you can put the drop onto the strip, or touch the drop onto the side of the strip and the blood will be drawn in by capillary action that is built into the strip.

Personally, although I have literally HUNDREDS of 21 gauge lancets, I still have somewhat better success with the commercial, one use, devices.

(For the CoagChek XS, and usually for the InRatio, some good pre-incision prep can help you get an adequate drop without making these devices absolutely necessary).

 

[CATDOG]

What GUAGE needle or blade?

What GUAGE needle or blade?

You say 21 GUAGE. I just stopped at the pharmacy and only saw 30 and 33 GUAGE on the shelf (for blood glucose monitoring). The pharmacist said 18 or 21 GUAGE would be for a cow! Is it really THAT much bigger or deeper? Do I really need a BIG HUGE drop? Can you give it 2 smaller drops, or would they be too far apart in time? Do I need something special?

 

[gerrychuck]

21 gauge is definitely harder to find, as the finer gauges, as you found, are far more common. I've tried the finer gauges, and they certainly don't get as big a drop; definitely not as effective for our purposes. Stay with the 21 gauge, either disposable lancets used with a lancing device or single use all in one lancets, if at all possible.

 

[Protimenow]

The word is gauge, not guage. And, yes, it should be 21 gauge. If you want some 21 gauge lancets, send me a PM -- I have more than I can EVER use.

Depending on the meter that is being used, you will require 10 - 20 microliters of blood to run a test. You will need 21 gauge, and will probably have to set your lancing device to make a deep enough incision. With the exception of the ProTime meters, you will have to get a single, large drop, and deposit on the strip within 15 seconds of making the incision.

There must be a lot of cows on this forum -- because we're using the 'cow' gauge lancets. (It sounds like that pharmacist is either ignorant of anything other than blood glucose testing, or just a bit of an *****). For most of my tests, I use Unistik 3 Extra lancing devices -- these are single use. They're 21 gauge. They make a deep enough incision for an adequate drop of blood. The lancets for blood glucose testing will NOT make an incision that is adequate for INR testing.

Moo

 

[catwoman]

You say 21 GUAGE. I just stopped at the pharmacy and only saw 30 and 33 GUAGE on the shelf (for blood glucose monitoring). The pharmacist said 18 or 21 GUAGE would be for a cow! Is it really THAT much bigger or deeper? Do I really need a BIG HUGE drop? Can you give it 2 smaller drops, or would they be too far apart in time? Do I need something special?

Not a cow, but maybe a dog or cat. I use 18g needles when giving fluids sub-q to a cat.

I bought some 26g universal lancets at a Walmart last week. Had bought 2 boxes of 21g lancets about 2-3 years ago (Walgreen's brand), and just opened the 2nd box last week. Walgreen's no longer carries the 21g lancets, but I did see some of the same online.

On capillary tubes: if I remember correctly, it's not advised to use them with the Protime 3. Seems I remember seeing that in the booklet with my first monitor. But that was 5+ years ago and I've slept a few times since then.

 

[Protimenow]

The ProTime 3 and ProTime are entirely different animals, when compared to the other meters. The ProTime meter does NOT use the first drop of blood -- in fact, it says to discard that drop. The capillary tubes are designed to take that first drop.

There's really no need to use a capillary tube with ProTime, anyway -- their strips come with a device that has a lancing thing (an icepick?) on one end, and a little collection cup on the other side. After you lance the finger and discard that first drop, you deposit what seems like a half gallon of blood into that little collection cup, then click the cup onto the test strip and press a button on the meter to draw that blood into the strip. Without the lancing device/collection cup (they call this a 'tenderlette'), you're not able to do the test.

BTW: I have a LOT of 21 gauge lancets - probably more than I'll be able to use even if I have quite a few more years left in me, if any of you want a box and are willing to pay for postage (probably a few bucks), PM me.

BTW2: I seem to have had slightly more success with the single use incision devices, but the lancet/lancing device combination is probably fine for the CoaguChek XS and maybe just slightly less perfectly suited for the InRatio and Coag-Sense.

 

[pellicle]

Hi

The 'tourniquet' that you mention is the thread/floss thing. Right?

yes, thats right. Fancy word for a simple thing

 

[Protimenow]

I'm wondering a bit about the 'tourniquet.' I used it today, below the second knuckle -- and wonder if there may be a pooling of interstitial fluid that dilutes the blood being tested. This was the biggest drop that I was able to get using this method and I just wonder about its impact on actual test results.

Here's the reason that I ask:

I tested using three meters
Coag-Sense: 3.0
CoaguChek XS: 3.3
InRatio 2: 4.8.

The first two tests were made minutes apart, using different fingers. The InRatio test was four hours later. The 'tourniquet' may have been a bit tighter, and on the finger for a bit longer than it was for the other tests.

In the past, the InRatio and CoaguChek XS usually gave similar values.

Any thoughts?

 

[pellicle]

Hi

firstly, did you post this before you posted the point on the other thread about the delay from using the same drop of blood??

I'm wondering a bit about the 'tourniquet.' I used it today, below the second knuckle -- and wonder if there may be a pooling of interstitial fluid that dilutes the blood being tested.

the XS relies on getting the first drop of blood, it also relies on there being tissue factors and all the other mixes of materials being there. So I don't think you can share it easily without causing difficulties.

With respect to "pooling" of interstitial fluids (I can only suppose plasma) it is important to not wrap that torniquet tight so that you feel a 'throbbing' and to not wrap it too low so as you may disturb the tissue factors. It is simply to stop the vascular removal of the blood that came to the capillaries escaping from what may be "light on blood" due to vasoconstriction (from there being cold for instance). I only apply the torniquet in the 5 or 10 seconds before lancing ...

This was the biggest drop that I was able to get using this method and I just wonder about its impact on actual test results.

Here's the reason that I ask:

I tested using three meters
Coag-Sense: 3.0
CoaguChek XS: 3.3
InRatio 2: 4.8.

The first two tests were made minutes apart, using different fingers. The InRatio test was four hours later. The 'tourniquet' may have been a bit tighter, and on the finger for a bit longer than it was for the other tests.

In the past, the InRatio and CoaguChek XS usually gave similar values.

Any thoughts?

aside from my other comment, mainly that the 3 and 3.3 values are more "what I'd expect" and that 4.8 seems a little high.

 

[Protimenow]

I'm going to retest using the InRatio and no tourniquet, on a finger that has healed a bit since the last incision. It's a day later, but I'll see if the value isn't closer to the 3.3 that the XS gave me yesterday.