En route.. Self testing

[zee112]

So I've performed my very first INR test at home this morning. The test returned an INR of 2.4. I was 2.8 when I left the clinic on the 9th of September. I feel very powerful and confident now with this knowledge and control over my life. I have one question. I understand that I am supposed to ensure the drop of blood is applied to the test strip within 15 seconds of lancing to ensure accuracy. If I applied a drop of blood within 5 seconds of lancing as opposed to say, 10 seconds, would the INR reading be different? Thanks!

 

[dick0236]

I doubt it.

 

[LondonAndy]

I doubt it too, but you have the power to find out now!

 

[pellicle]

Hi

If I applied a drop of blood within 5 seconds of lancing as opposed to say, 10 seconds, would the INR reading be different? Thanks!

Nope

There is an amount of leeway on that. One day when you feel like splurging done strips do some tests and see for yourself

But it would be hard to go longer than a minute.

To me the key ingredient is consistency, repeatability. Do it the same way each time and the results will likely be the same react m each time

 

[Protimenow]

The reason that they say fifteen seconds is because the blood 'begins to clot' after fifteen seconds. One second, five seconds, even fifteen seconds are safe. I doubt that you'd get a different result if you test any time within that fifteen second window. If you wait more than fifteen seconds, in theory, your INR would be somewhat lower than a blood draw would be. Imagine waiting a minute for testing, when your blood has done a significant amount of coagulating -- I'm not sure WHY they say fifteen seconds, or if 20 seconds would pose a problem, but it's safe to stay within the fifteen second rule.

Also - if you can't get a large enough drop within fifteen seconds, don't try to get another drop from the same incision - some clotting factors in your skin can make your INR test lower than it should.

If your initial test fails, for one reason or another, use a different finger for each successive test.

(A few years ago, when I was doing comparison testing of a few different meters - CoaguChek XS, Coag-Sense, InRatio, and sometimes Protime3, I ran through three or four fingers for each test - being certain to use a different finger for each test, and trying to get the testing done on each machine within minutes of the other machines. I did NOT try to get a second drop from ANY incision).

And, FWIW, the lab results often DON'T match the results from the meter -- the standard is that meter and lab are within 30% of each other's value.

 

[Warrick]

Yep I've stabbed 3 different fingers in a row because the blood drop wasn't big enough.... and then error 5, then afterwards they all decide to bleed....doah

how NOT to do it right

tried the rubber band trick but maybe I'm too neanderthal or hobbit fingers

 

[pellicle]

Yep I've stabbed 3 different fingers in a row because the blood drop wasn't big enough.... and then error 5, then afterwards they all decide to bleed....doah

yeah ... that used to be my norm

tried the rubber band trick but maybe I'm too neanderthal or hobbit fingers

so, how thick is your skin? Like do you have mechanics hands or panzy girly hands like (works in IT) me?

Are you winding DOWN the finger ... towards the tip?
Is your band firm enough? Like if you have thicker skin it may need to be tighter

Is your pinkie softer?

In winter in badly heated (NB Cold) homes (like in NZ) you may have vasoconstriction ... have you tried it after doing something like the washing up?

 

[Protimenow]

What you MAY be doing wrong is using the wrong lancing device or lancing technique. If you're using the lancets that are designed for blood glucose monitoring, it's almost a guarantee that you WON'T get a large enough drop for INR testing.

I've used the lancing devices that take the lancets -- and you MUST use 21 gauge lancets, set fairly deep on the device, in order to able to get a large enough incision to get a large enough drop. I have thousands (literally) of lancets that are made for this purpose - but I no longer use them. I have trouble giving them away because they cost so much to ship that you may as well buy them.

What I use now is the single use lancing devices that are MADE for INR testing. These make a large enough, deep enough (it isn't all THAT deep) incision so that, with a bit of proper preparation, you'll get a large enough drop. I've used Unistick, I've used Medline, and I'm sure that Roche probably has its own line of these devices. They typically cost about 25 cents each -- which is a lot less money than the cost of a wasted strip.

As far as prep is concerned, the rubber band works. Dental floss or thread works. Immersing your hand in warm water (or running warm water over your fingers for a minute or two) also works. Even swinging your arms around, to draw blood into your hands works. After all of this, and after self-testing for more than 7 years, I don't always get a useful drop of blood. But having the right lancing device, with the right size lancet and the correct depth setting, can reduce some of the error.

(One other thing - in contrast to Pellicle's photo of what looks like toilet paper on his fingers to catch the drops of blood), what I do is use a piece of paper towel after getting the drop onto the strip - I press it against the incision until the bleeding stops, then remove the paper towel. For me, I've found that there's a bit of a risk that the incision will reopen if I remove a piece of toilet paper from the clotted incision).

 

[Warrick]

95% of the time it all goes well, my skin is like a crocodiles,

I have the coaguchek lance and lancets ,was using it on 5 but found it just hurt more and didn't make much difference so have it on about 3.5

it's only when I'm in a rush to get to work that it seems to go pear shaped, I find a good rub beforehand gets it going (the finger)

 

[Warrick]

Would it make much difference if I switched to doing it in the evening when I take my dose as opposed to first thing in the morning? then I wouldn't rush it

 

[pellicle]

Would it make much difference if I switched to doing it in the evening

I don't see how it could, like INR is supposed to be stable within a day, so just do it when it's convenient.

Doesn't even really need to be the same day unless you are a nut job like me

 

[pellicle]

(One other thing - in contrast to Pellicle's photo of what looks like toilet paper on his fingers to catch the drops of blood),

It was a Norman Gunsten tribute.

Dubbed "the little Aussie bleeder" (a play on the term "Aussie battler"), he satirised parochial Australian culture, media "personalities" and egocentric talk show hosts.

 

[pellicle]

it's only when I'm in a rush to get to work that it seems to go pear shaped, I find a good rub beforehand gets it going...

Don't touch it baby, it's doing it all by itself...

 

[Protimenow]

Not being an Aussie, I didn't know about Norman Gunsten.

As far as time of day for testing, I usually do it late at night. However - I've found that I usually get a pretty good flow of blood if I test right after shaving -- warm water, hand movement, arm movement, that kind of thing.
For me, just running my hand under warm water for a few seconds, or squeezing my finger at just below the knuckle on the finger where I'll be taking the blood, usually gets enough blood to pool so that I can do an accurate test.

For any of us -- if you're using lancets and a lancing device, you don't have to go deeper than necessary to get a large enough drop. Whatever works for you should be fine.

(Also - as long as it's capillary blood, it probably doesn't even have to be a finger, although with a Coaguchek XS, touching your arm to the strip, or with a Coag-Sense, touching a transfer tube to another part of the body may not be easier than just using a fingertip.