ACT correlation_ Hemochron vs istat

I agree. They are apples to oranges and Werfen and Abbot will both back you on this, I'm certain. Contact your Technical/Application Specialists with each and let them know about what you're dealing with. 

They are not the same test; even though they share the same name. We have ACTLR and ACT+ on the new GEM100s and I correlate the + and LR assays across all devices, but not one assay to the other. I have lots of heparin response curves I've been collecting over the years and its very fascinating to superimpose a + and LR response curve, same donor or not. This visual should be more than clear enough to demonstrate that the assays are not the same. There are some in the cuvette package inserts, too. 

Good luck. Please keep us posted on developments. Feel free to email me.

Does anyone have a good resource on information to explain the differences between the Kaolin & Celite methodology? I am using the iSTAT ACT Celite and we have been using it for years for our Cath Lab. We have not had any issues with Heparin dosing or complaints from the Cath Lab, but I am not sure if I am using the best test? For the Labs above who use the iSTAT which test are you using Kaolin or Celite? 

Mary, I just sent someone our super awesome ACT comparison study we did way way back in 2013!! Can you believe that was over 10 years ago and yet here we are, still in the same boat with these issues. In our study we identified the OG ACT test from the 1970's (yes, the 1900's for you Gen Z'ers) - the Hemochron Response Celite Tube Method as the "Gold Standard" to which all other ACT methods since have attempted to automate because seriously, who has time to wait for blood to actually form a clot these days? Anywho, miraculously you actually had one of these 1970's beauties in the instrument dungeon of one of your labs and we were able to even drum up some supplies for that thing. We fired her up along side iSTAT ACTk set to Non-Warm mode, iSTAT ACTk set to Pre-Warm mode, Hemochron Jr. Signature with ACT+ cartridges, and good ole reliable HMS Hepcons, one with Heparin Assay cartridges and the other with HR-ACT cartridges. It was a doozy!
We sat in on four EP cases, each with an average of 7 draws per patient over the course of their procedure -two male and two female just to keep it on the up and up. I love this job, so fun! So what we found was, the iSTAT ACTk set to Non-Warm matched almost perfectly with Old-Man Hemochron Celite Tube method - the method from which all cardiologists on earth have set their target ranges for anticoagulation using heparin since the dawn of time. Those targets have not changed, what has is the instruments created to make measuring ACT faster - basically all automated ACT methods are now just calculations, and unfortunately those calculations are all different and have different use cases. In our case, we were happy with the iSTAT ACTk set to Non-Warm mode and henceforth all of those hospitals have used it without issue or complaint. Every so often we hear about the new guy that used the faster Hemocrhon Jr's in his old job and insists on using them now, and we have to bust out the old study we did showing him he's wrong and such :)  Kidding! You can correlate two things, and that doesn't mean equal. It can show they both go up with higher levels of heparin at the same rate, but do not give the same exact number, and that is fine - just explain that in your correlation study results. BUt also think about use case - as mentioned, using ACT during CPB is vastly different than using ACT in an EP case - choose accordingly. If one is specifically designed for high dose, then only compare to another high dose cartridge and vsv. Another place we looked was in the peer data from our CAP surveys and compared the SD and %CV for each method listed above. At that time, Hepcon was the best, iSTAT was second best, and Hemochron Jr was the worst - but we all know what those Hemochron Jr CAP specimens were like - you needed to do it just perfectly, or it was trash. So I digress. We plotted our data using EP Evaluator Multiple Instrument Comparison, and had the values from the Hemochron Response as the target. iSTAT ACTk Non-Warm was nearly identical, followed closely by Hepcon, then iSTAT ACTk in Prewarm showed a consistent negative bias, and Hemochron Jr. Signature ACT+ showed a consistent positive bias with some pretty crazy outliers to boot. That is how we convinced 500 cardiologists across 17 hospitals to change to iSTAT for EP/Cath - and were happy to keep our Hepcons in the OR for CPB. The end.

WOW!! Silka, thank you for sharing!!  10 years later and we're still trying to convince!  Thank you again so much for sharing your experience! 

Thank you Silka for all of the your information. That is very helpful and insightful.

We had one Cath Lab say they wanted the Hemochron because one of the providers thought it was faster and better. We actually found literature where a group of, I believe it was Cardiologists, did their own study on iSTAT vs Hemochron. Their conclusion was that iSTAT was was more consistent and reliable than the Hemochron. I presented that literature to the Cath Lab and, so far, they have not pursued the Hemochron any further. 

Ms. Clark - thank you for sharing this in depth information. I learned quite a bit that I was not aware of!

Thank you Silka for sharing such useful information.

Thank you Silka for the great reply!
We are also currently having this issue in our Cathlab thinking they are using more heparin lately with the i-Stat ACT-k than when they had Hemochron LR.  We are actively doing a 30 patient correlation study to our aPTT vs. the i-Stat value to prove to the docs that they need to adjust their cutoff values lower to than what they have been using.  It is insanely time consuming - but fun to sit in on PCI's and assist with this study.
What we are seeing is most of the time the docs are waiting 10-15mins after dosing heparin before running the ACT.  Abbott is recommending 5 mins post dosing as the ideal time frame, especially since it may take the doc an additional minute or three before they are able to get to drawing a blood sample while in the middle of PCI.  I am looking forward to collecting data on ACTs performed clsoer to the 5 minute mark to see if they are closer to that magical 250seconds my docs seem to be targeting.  

SIlka - would you be willing to share your study results? - I am particularly interested in the pre-warm vs. non-warm mode on both i-Stat machines.  What a great study you were able to perform - you should consider publishing it (if you haven't already)!

That study sounds interesting and a great idea. Hopefully you can share your data with us, I would appreciate it. Thank you for sharing.

If I start to hear rumblings around our units, I'm inviting you all to address them!

Suddenly one of our Anes Dr. wants to do a "study" using the Hemochron Sig Elite ACT-HR.  We've used iSTAT ACTK (prewarmed mode) in our facility for years so now are starting to do comparison studies so all of your comments are valuable!  We switched from the Hemochron 401/801 series which was a nightmare because they were never consistent on when to push the button, sometimes the tube was prewarmed, sometimes not.  We did see the lower values for prewarmed but we thought that was more reflectively of what was going on in the patient at 37 degree; warm blood clots faster.  Hemochron SE is prewarmed though so surprised you were seeing them higher as well.  We shall see....