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ACTLR Implementation problem with Sheath Pulls

ACTLR Implementation problem with Sheath Pulls

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We recently implemented ACT-LR at our facility in accordance with manufacturer recommendations. Unfortunately, our CVPR nurses are finding that ACTLR values are not dropping as expected post-surgery, leading to delays for removing sheaths and patient turnover. Our cutoff for a sheath pull is 170. ACTLRs are often staying over 200 long after surgery, but running an ACT+ on the same patient will give a more "normal" baseline under 170, which allows for the sheath pull. My CVPR nurses are now questioning the ACTLR assay after this has happened for several patients and they are often reverting to using the ACT+. 

Does anyone else have any experience with this or suggestions? I plan to call Werfen later this week for their feedback.

11 Replies
Joyce Moore
Mon Sep 12, 2022 at 1:06PM

My Cath Lab call the Sig Elites 'Random Number Generators'. We use 160 for sheath pull.

Brian Castle
Mon Sep 12, 2022 at 1:11PM

One important item of note is that the two cartridges use different activators:  ACT+ = kaolin, ACT-LR = celite.

Ken Charpie
Mon Sep 12, 2022 at 1:16PM

Random number generators! LOL

Derek Waggoner
Mon Sep 12, 2022 at 1:18PM

As Brian mentioned the two use different activators. As an example something like aprotinin will prolong the ACT-LR and have no effect on the ACT+.

Brandy Kenny
Mon Sep 12, 2022 at 1:42PM

We've had some of the same complaints with the ACT-LR. I just recently did a dose response curve with all our Sig Elites and it worked beautifully. My only explanation would be user error. Also, the ACT+ and the ACT-LR should have different ranges. They cannot be used in conjunction. Our ACT-LR sheath pull is set at 150. 

James Beck
Mon Sep 12, 2022 at 3:34PM

This chart goes back quite a few years, but I have always found it valuable.  If you look in the range (secs) of values you're targeting, if you extrapolate from this graph, you can see at around 150-250 seconds there is an approximate 50 second difference between ACT-LR (higher) and ACT+ (lower) - consistent with what you're seeing in your patients.  Second, ACT-LR is the method of choice for sheath pulls as it is attenuated for lower doses of heparin, unlike ACT+, which is for larger doses of heparin.  I would say it's not your method that you need to change, but rather your cutoff - which sounds like it was based on ACT+.
Attachment.
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Ken Charpie
Mon Sep 12, 2022 at 4:18PM

James, thank you for the detailed response and the chart. I've been trying to create my own comparing ACT+ to ACT-LR heparin response curves, but I find that every normal donor I use has such different responses to heparin (along with the inherent imprecision of the test), that it is incredibly difficult to generalize any kind of relationship between the two. The single donor they used for that chart has a really nice looking response curve across the AMR; but I'm finding that to not generally be true for all patients. There is often a huge plateau in the curve for most patients somewhere between 2 and 4 units / mL.

Aprotinin has been ruled out for the patients that did not see ACTLRs return to baseline as expected. 

How do other facilities determine their sheath pull cutoff? Ours was determined long before I became POCC and I have no resources that have provided that information. I've found a few facility sheath pull values posted online and ours seems to be a fairly normal cutoff at 170. I believe I had seen a facility that had a cutoff slightly over 200. 

I would love to propose revising our sheath pull cutoff upwards to accommodate this change in methodology. Any suggestions or resources for making this case to our cardiac program? I feel like ACT testing is the wild west of laboratory medicine sometimes... 

James Beck
Mon Sep 12, 2022 at 4:37PM

Wild west for sure - I have had similar frustrations with ACT!  As is probably the case with many facilities, I'd bet your sheath pull cutoff value was established many years back - probably when the only ACT test available was a tube test.  So, even more of an apples to oranges situation than just LR vs +.  And yes, the differing responses, patient to patient, to the same amount of heparin as reflected in their ACT is another variable to deal with - probably why that data was presented as a single donor example only.  Imperfect science to be sure.  Because the sheath pull decision is in most cases based on clinical information as well as the ACT, what I have done since moving to ACT-LR is informing medical staff that may be basing their decision on an ACT+ based cutoff, that LR values are roughly 50 seconds higher in this setting and allow them to make the appropriate informed decision.  I will also PM you the email address of the author of that article, Dr. Marcia Zucker, who is surely the go-to resource for all questions ACT.  I believe she also follows this listserve, so she may well see it herself.  Good luck!

Ken Charpie
Mon Sep 12, 2022 at 4:48PM

Thank you, James! This is probably the most helpful ACT conversation I've had with anyone yet. Dr Zucker is now in my mental notes and I am excited to have another resource to go to in this crazy area of lab medicine. I'll be looking for that article soon.

I started performing Heparin response correlations on all 7 of our devices in 2019 and now this includes ACTLR data. I try to track the employees donating each time to better understand how these tests can vary from person to person. I'm trying to assemble the data into easy-to-interpret response curves for educational purposes, but the graph you sent is already perfect for that.

Debra Howard
Tue Sep 13, 2022 at 6:50AM

There are some limitations with the Hemochron. Hematocrit levels should be between 20% and 55% due to an optical density outside the level of detection of the instrument. Things like foaming or hemolysis of the sample can also affect the results. Other things listed include clotted or partially clotted samples, unsuspected anticoagulation and lupus anticoagulant. A couple or so times a year there is discussion about the accuracy of the Hemochron ACT- LR. Ultimately some patients are unique and do not respond as expected. 
I know that you are discussing ACT LR but I would like to share what our CVOR does with ACT+. They start the case running the Hemochron ACT+ and the ISTAT ACT-k to get a baseline Throughout the case, they utilize the Hemochron. They then end the case with both. The ISTAT uses different technology that is not impacted by the limitations the the Hemochron has.

Debra Howard
Tue Sep 13, 2022 at 7:24AM

There are some limitations with the Hemochron. Hematocrit levels should be between 20% and 55% due to an optical density outside the level of detection of the instrument. Things like foaming or hemolysis of the sample can also affect the results. Other things listed include clotted or partially clotted samples, unsuspected anticoagulation and lupus anticoagulant. A couple or so times a year there is discussion about the accuracy of the Hemochron ACT- LR. Ultimately some patients are unique and do not respond as expected. 
 I know that you are discussing ACT LR but I would like to share what our CVOR does with ACT+. They start the case running the Hemochron ACT+ and the ISTAT ACT-k to get a baseline Throughout the case, they utilize the Hemochron. They then end the case with both. The ISTAT uses different technology that is not impacted by the limitations the the Hemochron has.

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Ken Charpie
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