Same Type machine +/- .5 inr?

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C

Country

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Jun 12, 2010
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92
Location
Montana
my docs office has been wanting me to bring my new INRatio 2 in to test against their Commercial version INRatio 2 machine.

the nurse stuck my fingar and then put one drop on their machine and then put the second drop on my machine.

their machine said 2.4_____ something...... mine said my inr was 2.9(hers shows pt)

does this sound like a difference inbetween the machines?

or is it possible, that using that second drop from the same stick messed up the reading?

now that i think about it i am a little worried of my inr last week. my machine showed i was at 1.7..... which if it is off by .5 then it would of put me down to 1.2!!!! that is not good!
 
Don't panic. Is there someone who is not on warfarin that you can test your monitor on? That reading should be 1.0 - 1.1.

Personally I would question the second drop of blood onto the test strip, but that's just me.
 
that is a great idea!!! i was thinking about testing my girlfriend a long time ago..... before i got my meter! and then it just slipped my mind!
 
well she should be home here in a little bit.... i will give her a finger stick then!
 
ok she made it home and agreed to the torture test..... i mean ehh an inr test

she tested out at a 0.9 INR

so i would say that my inratio 2 is accurate and it is either the docs machine is off or else it was the second drop of blood.

what say the gang?
 
me thinking it was the 2nd drop of blood.
Did the nurse have to "milk" your finger for that second sample? If she did, I would say, that would explain everything.
 
yes she had to "milk" it a little bit. that is something that i have had a problem with since i got my meter.

i dont believe that my lancets are large enough. i am going to be ordering some new strips soon and i will ask about larger lancets. the ones i have are orange and say that they are 23 gauge Unilet Excelite. larger ones would be 21 ga..... right?
 
I have the 21ga

You may want to try to "milk" your finger before using the lancet - hold the pressure and poke, the result should be a perfect sample for the test strip. Trying to force/milk a blood drop is a no-no (at least that is what was said to me at the pharmacy) and the sample that is being forced out is already thickening. Hope this makes sence.
 
ok yeah that sounds like it would work much better! I remember learning that to milk afterwards could give a false reading but i have been trying super hard just to get a drop of blood out of my fingers. i work with my hands for a living and that is why i am going to order larger lancets.
 
My lancets are also 21 gauge, yellow, and they make a nice quick little slice.
Using my baby finger is easiest, nice soft skin there, especially after I run the hand under warm water.
 
Country said:
my docs office has been wanting me to bring my new INRatio 2 in to test against their Commercial version INRatio 2 machine.

the nurse stuck my fingar and then put one drop on their machine and then put the second drop on my machine.

their machine said 2.4_____ something...... mine said my inr was 2.9(hers shows pt)

does this sound like a difference inbetween the machines?

or is it possible, that using that second drop from the same stick messed up the reading?

now that i think about it i am a little worried of my inr last week. my machine showed i was at 1.7..... which if it is off by .5 then it would of put me down to 1.2!!!! that is not good!
Click to expand...

Your machine tested 0.5 HIGHER than the "professional" machine...

SO, WHY would you think that if you measured a 1.7 that it was really 1.2?
Wouldn't it more likely be 2.2 ?

If you want to blow your mind, how about doing some consecutive tests on the Same Machine and see if there is a difference :)

Bottom Line: There is NO Gold Standard for INR testing, even lab draws.

On the positive side, INR testing is Way More Accurate and repeatable than Prothrombin Times from days of Olde when there was considerable variation in the reagents used for testing.

Testing a non-anticoagulated person and getting an INR of 1.0 only shows that the instrument is operating properly. It does NOT guarantee that the INR readings at higher levels are accurate.
Mathematically, matching at 1.0 is a necessary but NOT sufficient condition for determining accuracy over a range.

'AL Capshaw'
 
I just got a used InRatio and studied the training guide for professionals (presumably like the nurse who did the test with both meters), and the user manual for professionals. The material says that you should use the first drop of blood. The first drop has more thrombin and platelets (and other agents) that are designed to quickly close up cuts. The InRatio (and CoaguChek) devices are designed to use only that first drop of blood. Next time you go to your doctor, try first drop from two different fingers.

The materials also say that if you 'milk' your finger, you may dilute the blood and get an erroneous result. They recommend pressing on your finger (stopping the blood flow out of the finger) in order to get more blood to go out of the incision.

The also recommend a location at the fingertip that may be somewhat counter-intuitive (but you can get the PDF at the hemosense site to see the illustration) - the area just below the fingertip, to the left or the right of the fingertip. This may be just to make it easier to position that drop above the strip - but that's their recommendation.

Personally, for the InRatio (and the CoaguChek), I either use a 21 gauge lancet in a device that is set to maximum depth, or a single use lancing device that is supposed to get a big 20-40 ml drop of blood.

I spoke to Roche a couple weeks ago, and they recommended trying the pinky.
 
SO, WHY would you think that if you measured a 1.7 that it was really 1.2?
Wouldn't it more likely be 2.2 ?

if the docs office was reading right at 2.4 and mine was reading at 2.9 then mine is .5 higher then it should of been.... it should of read 2.4(theroretically if docs machine was right) so that would put my 1.7 from last week down to 1.2

however i think it was just a matter of using wrongful tactics.... i should have better results friday when i test again

thanks
 
Country said:
SO, WHY would you think that if you measured a 1.7 that it was really 1.2?
Wouldn't it more likely be 2.2 ?

if the docs office was reading right at 2.4 and mine was reading at 2.9 then mine is .5 higher then it should of been.... it should of read 2.4(theroretically if docs machine was right) so that would put my 1.7 from last week down to 1.2

however i think it was just a matter of using wrongful tactics.... i should have better results friday when i test again

thanks
Click to expand...

OOPS! I see your point.

OTOH, most fingerstick INR instruments operate with a Logarithmic function which means that the higher the number, the higher the possible variation / error (and the lower the number, the less the variation / error).
 
I tested with my InRatio today - using that first drop, and the location they recommend using in their manual (which is available online). This time, I did what they advised, warmed my hand in warm water for a minute or so, then incised where they advise (near the fingertip, to the right or left of the fingertip, just slightly back), used a 21 gauge lancet and the deepest setting on my lancing device and got a GOOD drop of blood. In fact, even with a 2.6 and pressure against a paper towel, it seemed to take quite a while to STOP bleeding. Normally, in the spot further away from the fingertip that I used to use, the flow of blood wouldn't be as good and the incised area would close up very quickly - sometimes without any encouragement.

But, again, first drop only. If confirming at your doctor's office, use a different finger for each test.
 
ALCapshaw2 said:
OTOH, most fingerstick INR instruments operate with a Logarithmic function which means that the higher the number, the higher the possible variation / error (and the lower the number, the less the variation / error).
Click to expand...

well that is definatally something to keep in mind. and i could see how that can be a huge problem.
 
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