Engineering student designing a new anticoagulant monitoring device

[Sammy Elashy]

Hello everyone,

My name is Sammy Elashy, I’m a senior Biomedical Engineering student at the University of Texas at San Antonio. I along with 4 other colleagues are currently doing our senior design project where we design and engineer a medical device. We’re currently in the early stages of engineering an anticoagulant monitoring device similar to CoaguChek and Coag-Sense. We’re currently looking for feedback from people that are using an INR measuring device and we plan on getting this feedback by having patients fill out a quick google form questionnaire on what they want to see in a new device, what they do/don’t like about their current one, issues with navigating the device, etc. The questionnaire does not ask for any personal information, it is completely anonymous and much appreciated. The link to the google form is right below:

Questionnaire For Prothrombin/INR Device

Thank you,
Sammy Elashy

 

[pellicle]

Hi

... so we can engineer a device that’s better than the ones currently on the market.

good luck with that. Roche has set a high bar and the Coag Sense before it started good and turned poor due to long term management issues.

I can answer your form in a sentence: the Coagcheck and my personal spreadsheet is the best there is.

Best Wishes

 

[Sammy Elashy]

Hi pellicle,

Thank you for the prompt reply. I read in your blog that you had issues getting a large enough blood sample for the device to read and that you had to place a rubber tourniquet on your finger in order to do so. Is this still an issue you are still experiencing? I was maybe hoping we could address this issue in our design

 

[pellicle]

Hi

Thank you for the prompt reply.

totally welcome

I read in your blog that you had issues getting a large enough blood sample for the device to read and that you had to place a rubber tourniquet on your finger in order to do so.

correct ... its actually quite a helpful approach. As I understand it many here have found the benefits of the rubber band approach in getting sufficient blood for a sample

Is this still an issue you are still experiencing?

I'm a bit lost, do you mean "am I still using the rubber band" ... yep, you becha

I was maybe hoping we could address this issue in our design

add a rubber band to what Roche provides.

Seriously, this is an issue of sample collection not INR determination. I'd be interested to read your literature review for your paper.

 

[Sammy Elashy]

I'm a bit lost, do you mean "am I still using the rubber band" ... yep, you becha

Yes that is what I meant, I apologize

add a rubber band to what Roche provides.

I'll definitely consider that for sure, thank you

Seriously, this is an issue of sample collection not INR determination. I'd be interested to read your literature review for your paper.

We're currently working on the project trying to see what improvements we can make to the ones on the market. If sample collection is a wide issue, I would love to talk to my team and see if we can find a solution to this issue.

So based off of what you're saying, the sample size required to get a reading is too big, is that correct?

 

[pellicle]

So based off of what you're saying, the sample size required to get a reading is too big, is that correct?

No, what I'm saying is that sample size is actually important for how the process of determining coagulation time is undertaken. Have you ever seen how much blood is drawn by a phlebotomist for uses at a lab?

The process is nothing like that of blood sugar analysis (where a smear is sufficient).

Before you can even hope to do a better job than Roche or Coag Sense I expect you'll need to understand the chemistry and the practical nature of assessment of that. Seems like you aren't across this yet (hence I asked about your reading list of articles). Feels like its well under PhD levels.

Best Wishes

 

[Sammy Elashy]

No, what I'm saying is that sample size is actually important for how the process of determining coagulation time is undertaken. Have you ever seen how much blood is drawn by a phlebotomist for uses at a lab?

Yes, I know that a phlebotomist takes several vials of blood. My question was regarding the issue with the "Error 5" message you kept getting due to an insufficient blood sample with the CoaguChek. The device requires a particular blood sample (8 ul) for the testing, and a finger prick alone without the rubber band seems ineffecient at supplying the minimum amount for a reading.

Before you can even hope to do a better job than Roche or Coag Sense I expect you'll need to understand the chemistry and the practical nature of assessment of that. Seems like you aren't across this yet (hence I asked about your reading list of articles). Feels like its well under PhD levels.

Yes, you're correct. I'm a senior undergraduate, so my knowledge on the topic is not that good, I do apologize for not making that clear at the start. I'm still in the process of reading articles and learning more about the chemistry and practicality of the assessment. Your blog makes it clear to me that you have a respectable amount of knowledge on this topic, more than the average person.

We're at the stage of design where we're required to reach out to folks who use these devices to learn more on what improvements, if any, can be made.

Do you have a list of articles you recommend I read to learn more by any chance?

Thank you for your time

 

[pellicle]

. The device requires a particular blood sample (8 ul) for the testing, and a finger prick alone without the rubber band seems ineffecient at supplying the minimum amount for a reading.

again, this is a lancing issue and not a device issue. People (including me) can and do get 8µL from the standard supplied lance, its just that depending on variables (like it being cold, performance anxiety, extremity circulation) the chances of getting this error are higher.

Its only those of use who are economic (or seeking to be) that are concerned about blowing a strip. The machines built in QA system ensures that a reading is either produced which is accurate or an error is declared.

The easiest way is to not be squeamish about it and do what's needed.

Best Wishes on your learning journey

 

[delucadana]

See if you can figure a way to measure INR without a blood sample. Think of a method like a continuous glucose monitor uses or an O2 saturation monitor.

 

[Protimenow]

It looks like you're trying to solve a problem that doesn't exist.

The issue is with blood collection -- Pellicle's rubber band (or dental twine) approach helps to pool the blood in the fingertip so there's more blood to collect on the strip (or in the pipette used by Coag-Sense - a meter that I no longer use).

There are a few ways of getting the blood to pool in the fingertip. If I had more floss or a supply of small rubber bands, I'd use Pellicle's method.

An awkward, and probably less useful device that you may develop - and probably won't be used - is an expensive alternative to the rubber band or twine that fits below the knuckle and compresses the tissue so a usable amount of blood is pooled in the fingertip - I can't see you developing a lancing device that does any better than what we already use.

I don't want a device that makes TOO LARGE an incision than is necessary, or one that makes one so small that it's not able to yield enough blood.

One issue that may be something to look at is how firmly you press on the lancing device to always get enough blood. This may vary from person to person (and even finger to finger - some of the fingers I've been using have developed scars so they don't reliably yield enough blood for testing. Remember, too, that blood must reach the meter within 15 seconds of making the incision for an accurate test.

 

[Protimenow]

A RELIABLE device that doesn't require a small incision wouldn't be bad - if at all possible. But when compared to the blood glucose devices that are read many times a day, the need for an INR device like this one - where tests are made weekly, and where the half life of warfarin is measured in days, not hours, there's probably little need for yet another device to tether to the body. OTOH - something that could be pressed to the skin and measure INR would be okay - but is probably impossible to develop, wouldn't be worth the cost, and would 'replace' a proven, perfectly good approach.

Less expensive strips would be nice - but wouldn't be a reason to switch from one meter to another.

Plus - a few things to consider:

You need a certain amount of blood in order to test for anticoagulation. A new device will probably need an amount similar to that required by the CoaguChek - and still require an incision - so what's the advantage of a new meter?

If a new meter only takes 15 seconds to report an INR, versus maybe a minute or so in the CoaguChek, where's the real advantage?

Getting the design approved by the FDA is probably a lengthy, expensive process. It probably makes no sense.

As a Senior design project, it may be an interesting exercise, but I doubt it will be something other than a thought experiment and, perhaps, an engineering challenge.

 

[Chuck C]

Good luck with your study Sammy. I'll do the survey later today or tomorrow.

 

[nobog]

A reasonable project, just one word of caution : Theranos

 

[Sammy Elashy]

A reasonable project, just one word of caution : Theranos

Thank you nobog, I'll keep that scandal in mind

 

[Sammy Elashy]

Good luck with your study Sammy. I'll do the survey later today or tomorrow.

Thank you Chuck, that is much appreciated

 

[Sammy Elashy]

Thank you so much Protimenow for the feedback, I'll definitely take these concerns into consideration. We're just trying to see if we are capable of addressing the issues that people are facing with current devices on the market.

 

[pellicle]

A reasonable project, just one word of caution : Theranos

especially given the suggestions of non-invasive magic measurement of "coagulation time" in the body where the body has evolved (from almost every mammal before us) to NOT have potentially fatal clots form while the coagulation machinery waits like a set trap to spring into action when actually needed for its highly specific purpose.

For @Sammy Elashy I'll add this diagram which he should be aware of:

 

[vitdoc]

Competition is always a good thing. With the advent of the novel anticoagulants the number of people on warfarin has dropped. Hopefully there will be enough still using warfarin for the medical industry to maintain the devices we have. If the numbers don't add up they might stop maintaining the product which would force us into warfarin clinic. I hope that day does not come. Also remember the increasing number of non mechanical valves. Warfarin's biggest thing going for it is it's cost.

 

[pellicle]

Warfarin's biggest thing going for it is it's cost.

ironically I'd also venture "its effect measurability" is #2, because we just don't know what the effect of the novel ACT is because AFAIK its not measurable

 

[Protimenow]

Warfarin's cost has been steadily creeping up for the past year or so. I used to get 90 day supply, without insurance, for about $10. Now, with insurance, it's more like $25 -- still not a lot compared to dollars per pill for the newer stuff.

I suspect that there will always be enough people taking warfarin (at least for some time) that it wouldn't be that big a problem for Roche (or others) to continue supplying strips -- and maybe making meters using the technologies that they've already developed. What's worked for the past five or six years (or longer) will continue working into the future - no re-engineering should be necessary.

I don't know if the anticoagulation effects of the new medications can be as easily reversed or overcome as the effects of warfarin (but, as I said, I don't really know).

IF the drug companies develop a product that keeps patients in range (and the range for one type of valve may be different from the range for a different type -- mitral vs. aortic), I'm not sure how well such a product will work -- price, as noted, may still be an issue.