Baseline ACT for CABG patients

Yes, there are known differences between ACT methodologies on the Hemochron vs on the I-stat.  They do not correlate 1:1 and their values should not be compared equally.  I would definitely question this correlation the surgery team did since there could be preanalytical issues seen with Hemochron vs. I-stat.  
In the 2 settings I have converted Hemochron to I-stat ACT, the data we collected between both analyzers was not very helpful at all.  The docs need to adjust their decision points and need to be fully aware of this issue - definitely get some re-education for all the physicians!

We use the Hemochron at our hospital. It is celite, not kaolin (I think the name Signature Elite might actually be a word play on the celite methodology). It is designed to detect a clot based on the rate of movement of the sample, which is monitored by a series of LED optical detectors that are aligned with the test channel. When the blood clots, the flow of the blood sample within the test channel is impeded, reducing its rate of flow between the optical detectors. This reduction in flow below a predetermined value signals to the instrument that a clot has formed. The iSTAT, on the other hand, uses a chemical measure of the presence of thrombin instead of a mechanical measurement of a physical clot.

So long story short, the two methods are definitely different and likely wouldn't compare. Heparin protocols will almost certainly be different depending on which ACT method is used.

SIGH!  We have had this issue for many years.  We currently run the ACT-Celite on ISTAT.  We switched to this MANY years ago from the Hemochron, but there are a number of physicians that just can't quite let go of the values.  We had a chart during implementation that they were supposed to use temporarily to see ISTAT value equals what in Hemochron value.  We have brought in Abbott for education.  What we have now decided to do is to have Abbott come in with an Implementation Specialist to do additional validation on the ISTAT and produce a Heparin Dose Response curve instead of that conversion chart that they just can't seem to part with.  Hemochron at least right now is not coming back.  We had numerous issues in the past with QC and Proficiency testing.  ISTAT was also more beneficial to add to our fleet because it did other testing the hospital needed besides coagulation.
When the Abbott Implementation Specialist comes in, our medical director has decided that we will switch to ACT-Kaolin for ISTAT from the Celite.  More references and material out there for kaolin and it is also cheaper for us with our supply contract.