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Do you know what kind of machine it was? The one I have now (inratio2) touts the following:
"The monitor performs the PT test AND 2 quality control tests (normal and therapeutic) simultaneously, and determines whether the controls are within preset limits. If they are, strip integrity is verified, and the monitor reports the PT test result. If they are not, the monitor displays an ERROR message."
This has given me some assurance that the values are correct, but I assume it could malfunction like anything else.
Dave
Dave
I will mention one thing with my meter. Each test strip has a code on it. After putting in the strip, I have to confirm the code...maybe they haven't been entering the code correctly?
By the way, what was the result of the blood draw?
I did speak to a hematologist yesterday, and he told me they won't use digital INR meters in their clinics as they are too unreliable.
I've been reviewing my recent readings, and I'm starting to get suspicious. On the same dose I have swung back and forth between 1.8 and 3.9 over the last several months.
Here is something I have always wondered...as soon as the drop starts pooling on the tip of my finger, doesn't it start to clot? What if one week it takes me 5 seconds from prick to reading, and the next it takes 35 seconds...would that skew the results? I'm guessing the meter must not rely on a fixed window...but I'm curious none the less. I need to look into how those machines actually work. If anyone knows, I'd love to hear.
fingerstick INR meters typically work this way:
when blood enters the test chamber, clotting is initiated by thromboplastin in the chamber (built into the test strip). Then magnetic fields move the blood around or measure the conductivity of the sample, or both, until the numbers do not change anymore. this indicates clot formation, as the iron in the blood or iron particles in the test chamber are no longer mobile.
quality control and calibration are automatic in all home-user devices i found, without the use of a calibration strip or liquid.
Testing i have seen on the Roche CoaguCheck series indicates it becomes very non-linear (inaccurate) at 4.0 or greater INR.
Inaccuracy increases if the finger stick to sample time exceeds 15 seconds (i believe most meters have a timer to eliminate over-aged samples).
Another factor in all fingerstick type tests (glucose, INR, etc) is the sample collection: milking of the finger, to oust a stubborn droplet from the wound, will decrease accuracy. Instructions state a "free hanging drop" for that reason.
I am thinking that with my target INR being 3.6, home testing is not for me yet. I'll take the monthly dr. visit for now.
I go to a clinic that has normally done blood draws sent to the lab for me, but because they had one patient who had trouble with the draws, they bought an INRatio 2 meter, which just happens to be the one I purchased.
At first I thought, "great! they have my meter! I won't need as much blood taken now!" - but I soon realized this is not good news, because the lab techs didn't know what the hell they were doing with the meter when they tried it with me last week, and I was horrified by this!!!
I actually had to tell them how to do it. My life is going to be in the hands of them and their misuse of the meter? No thanks. So today I have to go back there to get my INR checked, and I am going to insist that I only have a blood draw again like I used to. If they refuse, I will walk. Because I tested 1.3 when they did their botched reading, and when I got home, I tested 1.9 on mine. For me that's a big difference because I must be in 2.0-3.0 range.
I'm at least relieved to see that i'm not the only one here who has been through this. It is very frustrating to feel like my life is in the hands of people who don't know what they're doing and aren't detail-oriented enough to read the instructions properly or get proper training!