A quick video on my technique using the Roche CoaguChek XS

[pellicle]

Its been quite a while since I did my first video on using the XS and making some observations on that. I wanted to have another go at it but I'm not entirely happy with this production (lighting issues, perhaps location).

None the less I thought I'd present it here because its a bit more detailed than my older one and also examines the possibility of going over the 15 second guidance in the Roche documentation



I prefer to consider the rubber band as a pressure bandage not a torniquet because it does not cut off flow to the finger, merely restrict what movement occurs into the capillary system. I can not see how it could trigger any thrombosis to occur. Variously people have reported to me that; they really benefit from the rubber band to don't get a benefit.

My older video (which is only 45 seconds long) was done 8 years ago. It was a little hurried and had less discussion. I started using that device (yep, same one) in 2012.



I hope you find it helpful or at least a good basis for training if you (like me) never got any training at the start.

Best Wishes

 

[pellicle]

So, further to this, a discussion of my interest in doing this the other day with a member here (who's having a holiday) Leadville suggested that he'd also be interested in this experiment.

Unlike me, he doesn't use a rubber band (which sometimes I don't use either) but like me he suspected that leaving the blood off the strip longer would result in a reduced time detected by the Coagucheck. Perhaps because he doesn't use the rubber band he felt he could go longer than my attempt (which I'd shared with him before I put it on YouTube) and so he tried and did go for basically a whole minute from lance. When we compared notes we got the following data which I thought I'd graph.

His first lance duration between lance and application was a little longer than mine, and his INR a little higher.

What's interesting here is that we both got longer coagulation times not the anticipated shorter times. The slope on the trendline is slightly greater on mine.

Without knowing I feel that what this implies is

• because of the rounding which no doubt occurs I don't know if the INR of 2.4 represents 2.44 and that 2.5 does not represent 2.46 However I can report that the PT for my INR= 2.4 was 29 seconds and the PT for my INR = 2.5 was 29.7 seconds. Leadville INR / PT numbers were 2.9/35 and 3.1/37.5 ... before racing to interpret that the ISI value on his and my strip reagent is unknown (and that's what's part of the factoring in on the code chip)
• that whatever coagulation occurs between lance and application (and is thus untimed) is insignificant when compared to when the blood passes through the reagent, is exposed to the reagent in the strip and begins coagulation
• that whatever happens seems to cause a reading that becomes progressively higher. We both have the view that we don't have enough data to make any assumptions about the linearity of this (that would take more data points)
• I'm not about to conjecture if there is a curve that would fit this with such data, so a straight line is "the most I'm going to"

Either way we can see that straying outside the 15second guidance by Roche does have an effect (based on two sample patients with two entirely different batches of strips).

Lastly I don't believe that the Coaguchek XS PT test is an aPTT test because Roche sells that as well and its labelled differently and clearly

So far that's all I can say, other than try to measure within the 15 second rule but if you do go outside that, rather than waste a strip it would seem reasonable to just wait (even up to 20 seconds) to get that "hanging drop" rather than blow a strip.

Naturally I would encourage you to test this yourself in an organised way. In the above both tests were conducted within minutes of each other.

Best Wishes

 

[jeffp]

Lotta variables in there. Did the application of the hanging drop get applied at the same time during the 180 second countdown (does the wait time of the meter affect the reading)? Does the meter give the same reading time after time with the same sample and technique (testing repeatability)? Are the right now samples and the wait a bit samples the same size? That’d be a ton of strips to go through. I don’t have enough strips and free cash to do that kind of testing.
I’d wager that after adjusting for all the potential confounding factors, the result set would plot out to a nice Gaussian distribution. Somewhere Roche likely has these data hanging around somewhere, but figured with consistency, the results are clustered close enough to pass QA and gov’t approval.
I’d rather have it to self test and think it may be 2.8 or 3.1 but either way no problem than have to get lab draws every week and still not have an exact number I’d sleep comfortably with.
My only worry would be if it came up at, say, 4.2 and I bleed out while shaving.

 

[pellicle]

Hi Jeff

Lotta variables in there.

agreed, lots of potential variables, and only a few data points. While interpolation is impeded by lack of data points the two examples do follow the same pattern. It could be random but I doubt it. Did you read the rationale for the test (what it was trying to resolve)? Did you read my conclusions and what I think is a valid out-take from this?

Did the application of the hanging drop get applied at the same time during the 180 second countdown (does the wait time of the meter affect the reading)?

yes they did, and (regarding wait time, according to Roche no).

Does the meter give the same reading time after time with the same sample and technique (testing repeatability)?

in my experience yes, but with the clarification about possible rounding issues as I mentioned above (2.44 vs 2.46) ... in the main when I've done this it shows the same number. Even between batches.

Are the right now samples and the wait a bit samples the same size?

well 1) did you watch the video? 2) the strip is designed (if you look at it) to use capillary attraction to draw only a small section of the blood down into the chamber (and in all likelihood across the reagent). This means that the sample size tested by the meter is identical each time and is essentially a random sample of a fluid.

That’d be a ton of strips to go through. I don’t have enough strips and free cash to do that kind of testing.

I'd suggest decent experimental design and so you don't just use scatter gun and then give a ton of data which may or may not be helpful.

I’d wager that after adjusting for all the potential confounding factors, the result set would plot out to a nice Gaussian distribution.

I'd wager either something linear or something like a curve. Either way what do you actually identify as being a flaw in this experiment designed to determine a single point (NB that of what effect does wait time on strip application have on read INR).

My only worry would be if it came up at, say, 4.2 and I bleed out while shaving.

that's exactly my worry too, but these days I only shave my legs (and only for MardiGras in Sydney)

With all your above questions, were you being at all serious or just attempting to throw 5hit around? I took them seriously (except for the obvious last one). If you were not then why make an extended post to attempt to ridicule?

Best Wishes

 

[Protimenow]

The curve may be linear - but understanding the mechanism behind clotting, it may be linear up to a point -- the point at which a definite clot has formed. At this point the clotted - or almost clotted droplet of blood might not even make its way, via capillary action, onto the strip.

If the results shown can be replicated, I don't see much of an issue with results - even a minute or so after incising the finger -- the highest number is still safe.

I can see Roche and Coagusense, which also suggests the fifteen second rule, advise the 15 second window for the highest level of accuracy. Although less accurate, it looks as if testing more than fifteen seconds after making the incision may give a slightly elevated result than it should, but it probably isn't that big an issue for INRs below, perhaps, 3.8 (an absolute guess) or so.

 

[ATHENS1964]

I would like to ask when we travel and go through baggage control, do the strips have a problem with the machines that scan the baggage?

 

[pellicle]

I would like to ask when we travel and go through baggage control, do the strips have a problem with the machines that scan the baggage?

I have never seen such an influence. I don't think the chemistry would be effected by it as now days the radiation emissions are very low and it no longer even effects photographic films (of high ISO levels).
Given the chemistry isn't photo sensitive I'd say that just like your own body isn't damaged by that level of radiation the strips would be less so.
Google searching reveals nothing, have you considered asking Roche (knowing that you are a reseller)

 

[pellicle]

At this point the clotted - or almost clotted droplet of blood might not even make its way, via capillary action, onto the strip.

well 1) that is not how coagulation works, its a molecular process which is much more like the way gelatine sets (or agar). It does not form granules but thickens and 2)if blood was clotting so fast without the presence of a reagent it would suggest something really strange going on because the blood doesn't even clot in test tubes or when you donate blood.

This is backed up by other things I've posted here (not so long ago) and so a quick search yeilds this collection and processing instructions:

https://www.geisingermedicallabs.com/catalog/details.cfm?tid=1406

If analysis occurs within 24 hours whole blood may be used and no processing needed.​

 

[ATHENS1964]

Δεν έχω ξαναδεί τέτοια επιρροή. Δεν νομίζω ότι η χημεία θα επηρεαζόταν από αυτό, καθώς τώρα οι εκπομπές ακτινοβολίας είναι πολύ χαμηλές και δεν επηρεάζει πλέον ούτε φωτογραφικά φιλμ (υψηλών επιπέδων ISO).
Δεδομένου ότι η χημεία δεν είναι φωτοευαίσθητη, θα έλεγα ότι όπως και το σώμα σας δεν έχει υποστεί ζημιά από αυτό το επίπεδο ακτινοβολίας, οι λωρίδες θα ήταν λιγότερο.
Η αναζήτηση στο Google δεν αποκαλύπτει τίποτα, έχετε σκεφτεί να ρωτήσετε τη Roche (γνωρίζοντας ότι είστε μεταπωλητής)

Δεν έχω ξαναδεί τέτοια επιρροή. Δεν νομίζω ότι η χημεία θα επηρεαζόταν από αυτό, καθώς τώρα οι εκπομπές ακτινοβολίας είναι πολύ χαμηλές και δεν επηρεάζει πλέον ούτε φωτογραφικά φιλμ (υψηλών επιπέδων ISO).
Δεδομένου ότι η χημεία δεν είναι φωτοευαίσθητη, θα έλεγα ότι όπως και το σώμα σας δεν έχει υποστεί ζημιά από αυτό το επίπεδο ακτινοβολίας, οι λωρίδες θα ήταν λιγότερο.
Η αναζήτηση στο Google δεν αποκαλύπτει τίποτα, έχετε σκεφτεί να ρωτήσετε τη Roche (γνωρίζοντας ότι είστε μεταπωλητής)

Θα στείλω email στη Roche και όταν έχω απάντηση θα σας ενημερώσω

I have never seen such an influence. I don't think the chemistry would be effected by it as now days the radiation emissions are very low and it no longer even effects photographic films (of high ISO levels).
Given the chemistry isn't photo sensitive I'd say that just like your own body isn't damaged by that level of radiation the strips would be less so.
Google searching reveals nothing, have you considered asking Roche (knowing that you are a reseller)

I will email Roche and when I have a response I will let you know

 

[tom in MO]

Per the data, 2.4 and 2.5 are within the meter's error range, as is 2.9 and 3.1. So there is essentially no difference between each person's two readings. There is a difference between Pellicle and leadville. I was a little surprised to see Pellicle runs his INR at 2.5, I would of thought he'd be closer to 3...proof is in the pudding. Your results are in my target range of 2-2.5.

Although two points define a line in math, in science, two points do not give sufficient data to conclude a relationship is linear. You should remove your lines and their equation. They are invalid. The number of points to tell a difference should be based upon the measurement system's precision and accuracy.

 

[Protimenow]

well 1) that is not how coagulation works, its a molecular process which is much more like the way gelatine sets (or agar). It does not form granules but thickens and 2)if blood was clotting so fast without the presence of a reagent it would suggest something really strange going on because the blood doesn't even clot in test tubes or when you donate blood.

This is backed up by other things I've posted here (not so long ago) and so a quick search yeilds this collection and processing instructions:

https://www.geisingermedicallabs.com/catalog/details.cfm?tid=1406

​

If analysis occurs within 24 hours whole blood may be used and no processing needed.​

Maybe I wasn't clear enough. What I was saying was what you were, basically, asserting - that blood that had already clotted (in your example, turned gelatinous) wouldn't be drawn into the strip.

 

[ATHENS1964]

There are a number of possible physiological test interferences.  Bilirubin > 513 µmol/L (30mg/dl)  Hemolysis > 0.62mmol/L (1000mg/dl)  Hematocrit ranges below 25% and above 55%.  Triglycerides > 5.7mmol/L (500mg/dl)  Heparin concentrations > 0.8 U/ml  The CoaguChek® PT Test is insensitive to low molecular weight heparis (LMWH) up to 2IU/ml antifactor xa activity.
See link pdf file page 6
https://policyonline.nhslothian.sco...Coaguchek Device to monitor INR Procedure.pdf

 

[pellicle]

Morning

Maybe I wasn't clear enough. What I was saying was what you were, basically, asserting - that blood that had already clotted (in your example, turned gelatinous) wouldn't be drawn into the strip.

and what I was saying is that's not possible. As I mentioned, in a plain tube with a cap its fine for 24 hours, so even 2 minutes its not going to be coagulated. Have you ever dealt with blood?

As I posted above from that procedure manual:

If analysis occurs within 24 hours whole blood may be used and no processing needed.​

 

[pellicle]

There are a number of possible physiological test interferences.  Bilirubin > 513 µmol/L (30mg/dl)  Hemolysis > 0.62mmol/L (1000mg/dl)  Hematocrit ranges below 25% and above 55%.  Triglycerides > 5.7mmol/L (500mg/dl)  Heparin concentrations > 0.8 U/ml  The CoaguChek® PT Test is insensitive to low molecular weight heparis (LMWH) up to 2IU/ml antifactor xa activity.
See link pdf file page 6
https://policyonline.nhslothian.sco...Coaguchek Device to monitor INR Procedure.pdf

agreed ... these are also discussed in the Roche Manual (which I anticipate nobody reads). In particular the Hematocrit levels, although Roche claims that it is not effected by heparins.

 

[Dunwanted]

Thanks for the update video, i just got my machine recently tried to times and got an error then tried your method and worked.

 

[ATHENS1964]

I have never seen such an influence. I don't think the chemistry would be effected by it as now days the radiation emissions are very low and it no longer even effects photographic films (of high ISO levels).
Given the chemistry isn't photo sensitive I'd say that just like your own body isn't damaged by that level of radiation the strips would be less so.
Google searching reveals nothing, have you considered asking Roche (knowing that you are a reseller)

I received a reply from Roche Hellas, it was in Greek, sorry again for the translation.

Dear Sir / Madam,
On the occasion of your query through the contact form of www.roche.gr, we inform you of the following:
It is indeed safe to travel with Coaguchek XS. The purpose of this device is that the patient can take it anywhere and take the necessary measurements whenever needed.
There are no existing clinical studies on the effect of X-rays on Coaguchek devices or test strips. Also so far we have not received any information from the market about an incident where an issue has occurred under the circumstances you describe.
At your disposal for more information.

Konstantinos Stavropoulos
Associate Marketing Manager (MSc, MBA)
Roche Diagnostics (Hellas) S.A.
18 - 20 Amaroussiou - Chalandriou Str.
151 25 Maroussi, Greece

 

[user 15848]

Its been quite a while since I did my first video on using the XS and making some observations on that. I wanted to have another go at it but I'm not entirely happy with this production (lighting issues, perhaps location).

Thank you.