![]() 16–7027-BO) was obtained and informed consent of patients was waived because of pseudomisation of all data. Ethics committee approval (Ethik-Kommission Medizinische Fakultät der Universität Duisburg-Essen, Robert-Koch-Straße 9–11, D-45147 Essen, Germany, protocol no. To assess the agreement, concordance, and interchangebility of ACT measurements for cardiac surgery two commonly used devices for ACT monitoring were compared assessing deviations between measurements on the same device as well as between different devices, i.e., an i-STAT device was compared to the Hemochron. Although both methods are approved for clinical use, their reproducibility, agreement, and interchangeability have not been well investigated so far. While the former methods are affected by thrombin generation, platelet aggregation, and fibrin polymerization, the latter assay only depends on thrombin generation, potentially resulting in measurements more precisely reflecting Heparins anti-thrombin properties. Another method, as used in the i-STAT (Abbot Point-of-Care, Princeton, NJ, USA), is based on the electrochemical detection of a product derived from thrombin dependent cleavage of a substrate other than fibrinogen (Phenylalanin-Pipecolyl-Arginin-NH 3-C 6H 4-NH-C 6H 4-OCH 3). Most devices, like the Hemochron Signature Elite (Accriva, San Diego, CA, USA) used in our study, assess the ACT by mechanical or photo-optical detection of thrombin induced clot formation. Following its initial description by Hattersley in 1966, the Activated Coagulation Time (ACT) has been developed to be usable as a point of care (POC) test. However, long turnaround times and the high heparin concentrations required to prevent blood clotting in the bypass circuit hamper the intraoperative usefulness of these latter assays in cardiac surgery. Ever since, activated partial thromboplastin time and anti-factor-Xa assays are considered the gold standard for monitoring Heparin induced anticoagulation. Up to the 1970s whole blood clotting time was used to monitor Heparin’s anticoagulant effects. Unfractionated Heparin (UFH) is the standard anticoagulant for cardiac surgery involving cardiopulmonary bypass (CPB) circuits since 1953. Furthermore, our data question the reliability of the Hemochron in assessing adequacy of heparin anticoagulation monitoring for CPB. ConclusionĬurrently used ACT point-of-care devices cannot be used interchangeably. Furthermore, while discrepancies in ACT between two parallel iSTAT assays showed little or no clinical relevance, deviations from parallel Hemochron assays and iSTAT versus Hemochron measurements revealed marked and sometimes clinically critical deviations. ![]() Overall, disconcordant results according to clinically predefined target values were more frequent with the Hemochron than i-STAT. Although demonstrating a fair linear correlation (r = 0.815), parallel measurements on different ACT-devices showed large bias (−20s 95% LOA: − 290-250 s) and little concordance (kappa = 0.368). Hemochron derived ACTs demonstrated worse linear correlation (r = 0.782), larger bias with considerably broader LOA (− 13.14 s 95%LOA:-316.3–290 s), and lesser concordance between parallel assays (kappa = 0.554). Bias, as determined by Bland-Altman analysis, was low (− 3.8 s 95% limits of agreement (LOA): − 77.8 -70.2 s), and Cohen’s Kappa demonstrated good agreement (kappa = 0.809). Parallel i-STAT ACTs demonstrated a good linear correlation (r = 0.985). Measurements were compared between identical and different device types using linear regression, Bland-Altman analyses, and calculation of Cohen’s kappa coefficient. Blood samples from 30 patients undergoing cardiac surgery on CPB were assayed at specified steps (baseline, after heparin administration, after protamine administration) with four parallel measurements (two of each device type) using commercial Kaolin activated assays provided by the respective manufactures. ![]() We evaluated the agreement of ACT assays using four parallel measurements performed on two commonly used devices each (i.e., two Hemochron Signature Elite (Hemochron) and two Abbott i-STAT (i-STAT) devices, respectively). However, concerns exist regarding reproducibility of ACT assays and comparability of devices. Since inadequate heparin anticoagulation and insufficient reversal can result in complications during cardiopulmonary bypass (CPB) surgery, heparin anticoagulation monitoring by point-of-care (POC) activated clotting time (ACT) measurements is essential for CPB initiation, maintainance, and anticoagulant reversal.
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