LAUSR

Point-of-care (POC) activated clotting time (ACT) testing allows for the rapid and reliable assessment of hemostasis in patients undergoing heparin therapy. This is crucial for the safe management of patients during cardiopulmonary bypass, ablation in the electrophysiology laboratory, interventions in the catheterization laboratory, or extracorporeal membrane oxygenation. Three different POC ACT testing systems were being used at our institution, the HMS Plus Hemostasis Management System (HMS), Hemochron Signature Elite (Hemochron), and GEM PCL PLUS (GEM PCL). A review of performance records suggested variations in ACT measurement. We hypothesized that the observed variations in ACT measurement could be attributed to each system utilizing a different testing method. In addition, none of these POC ACT systems was connected with the electronic health record (EHR), so results were manually entered. Lack of electronic capture of results increases the potential for results to be left out of the EHR. i-STATs are widely used at our institution and are connected with the EHR. Literature reports show that the i-STAT ACT has acceptable performance, so we decided to compare the existing ACT systems to the i-STATACTwith the goal of potentially replacing all three POC systems with the i-STAT. Leftover whole blood samples collected from patients undergoing heparin therapy were tested by i-STAT following testing by one of the three existing instruments. 41 samples were analyzed on both the HMS and i-STAT, and Hemochron and i-STAT, but only 25 samples were analyzed on both the GEM PCL and i-STAT due to nonavailability of samples. Existing ACT assays were used as the reference methods. Results were compared by Deming regression and Bland-Altman plots. Correlation between HMS and i-STAT had a slope of 1.26 and an intercept of –80.2 seconds. i-STAT was negatively biased to the HMS on average by – 7.6 seconds (–2.7%). Correlation between Hemochron and i-STAT had a slope of 0.21 and an intercept of 109.9 seconds. i-STAT was negatively biased to the Hemochron on average by –63.6 seconds (–34.0%). Correlation between GEM PCL and i-STAT had a slope of 0.68 and an intercept of 39.4 seconds. i-STATwas negatively biased to the GEM PCL on average by –19.1 seconds (–10.3%). i-STAT ACT values were lower compared to all three existing ACT systems, with the biggest bias observed with Hemochron. Observed variability between all four systems is likely due to lack of standardization of ACT methods. Using multiple methods within the same institution may confound the interpretation of the anticoagulation status of the patient. It would be advantageous to limit the number of different ACT test systems within our institution. Streamlining ACT testing so it was limited to the i-STAT required educating clinicians about the expected difference in ACT results when using i-STAT as opposed to existing methods. AJCP / MEETING ABSTRACTS