INR for mechanical AV

[chaconne]

Maintaining 1.8-2.2 seems like it would be impossible to me. Most of the time I test (home or lab) I'm close to 3.0. But every few tests I tend to get a dip for no apparent reason. The last one was a week ago when I measured 2.1 on my INRatio2. I decided to do nothing and retested in 4 days. It went up to 3.0.

 

[Protimenow]

Wow. Yotphix said it a lot better than I did.

 

[tom in MO]

I agree totally that "a little anti-coagulation doesn't need to hold you back, even if it stays in the upper 2's as mine generally does." I forgot to put a smiley after "hemopheliac."

I am trying to offer a little counterpoint to the theme of "running high with the INR is safer" and to make sure people understand that the "correct range" can change. If the range can change, it's certainly not an absolute...but then neither is the measurement of INR, it's a normalized ratio of reaction rates.

I have an "older" model valve, that had the old 2-3 range and the "new" range is 2-2.5. Last March, there was disagreement between my three doctors (surgeon, cardio, INR) as to which range to apply, thus the "new" range may really be new for some medical professionals.

It is possible to maintain a 2-2.5 range with biweekly home testing.

 

[Protimenow]

Personally, I would still stay away from the low end of the range, in order to account for error in the tests. During the time when I was able to get monthly blood draws, my INR as reported by the InRatio and InRatio 2 was ALWAYS higher than the lab tests - in some cases, it was as much as .6 higher.

In my recent testing, I found that the InRatio 2 and CoaguChek XS were both either the same or within .1 of each other. Personally, I wouldn't bet my life on continuing with an InRatio or CoaguChek XS-reported INR of 2.0. I would be concerned that the actual value might be below 2.0. I would feel more confident of being in the safe zone if my testing - whatever method I used - reported at least 2.4 or 2.5.

This is just my personal opinion, of course, but I don't see any negatives to keeping the reported INR a bit above the bottom of the range and helping to prevent clot formation.

 

[chaconne]

If it were possible/practical, I would really like to see a time history plot INR over a few weeks with a measurement every few minutes. I wonder what fluctuations would show up at such a relatively high time resolution. Is the INR always the same in blood everywhere in the body at a given instant? Even if there are changes in the INR on the order of hours or minutes, we wouldn't be able to adjust for them with Warfarin.

I nominate Protimenow to begin testing every few minutes for the next few weeks to get some high-resolution INR data

 

[yotphix]

There was a fellow on here from England who was doing some very high resolution testing, but he was also making frequent dosing adjustments too, as I recall. If I couldn't think of anything better to do with the money, I'd gladly test three times a day for 4 weeks, and maybe even simultaneously from a finger and a toe just to see what the variations were, and whether there were any patterns. That'd be close to 800 dollars though, in rough terms, and I'm not quite 800 dollars curious! I do know that i make it a point to test at different times of day, and on different days of the week now, and I am still very consistently in range, which leads me to believe that this is a fairly consistent and reliable therapy.

 

[pellicle]

Hi

dollars curious! I do know that i make it a point to test at different times of day, and on different days of the week now, and I am still very consistently in range, which leads me to believe that this is a fairly consistent and reliable therapy.

Interesting. Does this mean that you are testing weekly on random days for that week? Does this mean that sometimes there may be 12 days between tests?

This sounds attractive. I may consider this. As it happens I measure on Saturdays, withoccasional mid week testing. My results seem to show variations but I am not sure if this is diet related or due to other variations in metabolism.

 

[Protimenow]

Interesting nomination.

In order to do this, I don't think any meter - other than, perhaps, the ProTime meters, would be able to do the testing. The InRatio, CoaguChek XS and, supposedly, the Coag-Sense all ask for blood taken within fifteen seconds of making the incision -- that's because these meters factor in clotting agents that are in the skin. Only the Protime wants you to discard the first drop.

With the ProTime meter, it's conceivable that an IV can be used to extract enough venous blood for testing every few minutes. Of course, I realize that your suggestion takes the idea of testing to the extremes of absurdity. Even if the blood from my heel, perhaps, gives me a different INR reading from the blood in the fingertip, I don't think that there will be much that can be done about it as far as dosing is concerned.

Still, I wouldn't be terribly surprised if we aren't able to do an INR test - perhaps even non-invasively - with our smartphones a few years from now. I can take my pulse by touching a fingertip to my phone's camera lens; my phone can watch my eyes while I read from it and can determine when to go to the next page; my phone can also (supposedly) sense my hand motions when I move it above the screen. Perhaps someone can figure out a biological indicator that can reflect INR just by watching something on or below the skin's surface. (The InRatio and CoaguChek XS detect INR using amperage changes when blood and reagent mix - they don't look for actual clots). If, at some point in the future, we CAN test INR non-invasively, Chaconne's suggestion may actually become possible.

(However, I suspect that if there's a cheap, easy way to test INR without having to buy strips or a meter, the manufacturers of meters and strips will probably move pretty quickly to squash this)