Platelet-activated Clotting Time Does Not Measure Platelet Reactivity during Cardiac Surgery 

1999 ◽  
Vol 91 (2) ◽  
pp. 362-368 ◽  
Author(s):  
Linda Shore-Lesserson ◽  
Tameshwar Ammar ◽  
Marietta DePerio ◽  
Frances Vela-Cantos ◽  
Cherie Fisher ◽  
...  
Keyword(s):  
Cardiac Surgery ◽  
Blood Loss ◽  
Chest Tube ◽  
Platelet Reactivity ◽  
Thrombin Receptor ◽  
Clotting Time ◽  
Platelet Dysfunction ◽  
Tube Drainage ◽  
Activated Clotting Time ◽  
Protamine Administration

Background Platelet dysfunction is a major contributor to bleeding after cardiopulmonary bypass (CPB), yet it remains difficult to diagnose. A point-of-care monitor, the platelet-activated clotting time (PACT), measures accelerated shortening of the kaolin-activated clotting time by addition of platelet activating factor. The authors sought to evaluate the clinical utility of the PACT by conducting serial measurements of PACT during cardiac surgery and correlating postoperative measurements with blood loss. Methods In 50 cardiac surgical patients, blood was sampled at 10 time points to measure PACT. Simultaneously, platelet reactivity was measured by the thrombin receptor agonist peptide-induced expression of P-selectin, using flow cytometry. These tests were temporally analyzed. PACT values, P-selectin expression, and other coagulation tests were analyzed for correlation with postoperative chest tube drainage. Results PACT and P-selectin expression were maximally reduced after protamine administration. Changes in PACT did not correlate with changes in P-selectin expression at any time interval. Total 8-h chest tube drainage did not correlate with any coagulation test at any time point except with P-selectin expression after protamine administration (r = -0.4; P = 0.03). Conclusions The platelet dysfunction associated with CPB may be a result of depressed platelet reactivity, as shown by thrombin receptor activating peptide-induced P-selectin expression. Changes in PACT did not correlate with blood loss or with changes in P-selectin expression suggesting that PACT is not a specific measure of platelet reactivity.

scholarly journals Comparison of activated clotting times measured using the Hemochron Jr. Signature and Medtronic ACT Plus during cardiopulmonary bypass with acute normovolemic haemodilution

2017 ◽  
Vol 46 (2) ◽  
pp. 873-882 ◽  
Author(s):  
Jung Min Lee ◽  
Eun Young Park ◽  
Kyung Mi Kim ◽  
Jong Chan Won ◽  
Tack Koon Jung ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Cardiac Surgery ◽  
Cardiopulmonary Bypass ◽  
Bolus Dose ◽  
Blood Glucose Concentration ◽  
Altman Analysis ◽  
Clotting Time ◽  
Bland Altman Analysis ◽  
Activated Clotting Time ◽  
Protamine Administration

Objective This study compared the activated clotting time (ACT) measured using the Hemochron Jr. Signature (HACT) with the ACT measured using the Medtronic ACT Plus (MACT) during cardiopulmonary bypass (CPB) with acute normovolemic haemodilution (ANH) in patients undergoing cardiac surgery. Methods The ACT was checked at baseline with both devices after inducing anaesthesia, and 400 to 800 mL of whole blood was withdrawn to induce moderate ANH. Before initiating CPB, a 300-IU/kg bolus dose of heparin was administered to maintain the HACT at >400 s; protamine was later given to reverse the anticoagulation. The ACT was checked using both devices at baseline, during heparinisation, and after protamine administration. Results In total, 106 pairs of samples from 29 patients were analysed. The ACT showed a good correlation between the two devices (r = 0.956). However, Bland–Altman analysis showed that the MACT was higher, particularly at baseline and during heparinisation. Multiple regression analysis showed that the blood glucose concentration significantly influenced the differences between the two ACT devices. Conclusions The HACT was lower than the MACT during CPB with ANH in patients undergoing cardiac surgery. Clinicians should be cautious when using each ACT device within generally accepted reference ACT values.

Shear-Induced Pathway of Platelet Function in Cardiac Surgery

1995 ◽  
Vol 21 (S 02) ◽  
pp. 66-70 ◽  
Author(s):  
Noriyuki Tabuchi ◽  
Izaak Tigchelaar ◽  
Willem Van Oeveren
Keyword(s):  
Cardiac Surgery ◽  
Cardiopulmonary Bypass ◽  
Platelet Function ◽  
Chest Drain ◽  
Clotting Time ◽  
Platelet Dysfunction ◽  
Excessive Bleeding ◽  
Activated Clotting Time ◽  
Proper Diagnosis

The contribution of platelet dysfunction to the impaired hemostasis after cardiac surgery remains to be established, because there is no sensitive method to assess platelet function. Measurement of the shear-induced pathway of platelet function, an important mechanism in inducing hemostasis, became possible by a novel shear-inducing technique, the in-vitro bleeding test (Thrombostat 4000). By using this test, the changes in platelet function during cardiopulmonary bypass and their contribution to hemostasis were investigated in patients undergoing cardiac surgery. Platelet function is quickly impaired shortly after the start of cardiopulmonary bypass, and partly recovered at the end of cardiopulmonary bypass. The function of aspirin-treated platelets is more severely affected than of nonaspirin platelets during cardiopulmonary bypass. Furthermore, the degree of platelet dysfunction at the end of the operation, but neither the platelet number nor the activated clotting time, was significantly correlated with blood loss from the chest drain after cardiac surgery. These results indicate the significant and variable effects of cardiopulmonary bypass on the shear-induced pathway of platelet function. Moreover, the impairment of this function of platelets appears to be a major cause of excessive bleeding in patients after cardiac surgery. Therefore, the routine use of the shear-inducing test seems helpful to make a proper diagnosis and design the therapy for bleeders after cardiac surgery.

scholarly journals Point-of-Care Measurement of Activated Clotting Time for Cardiac Surgery as measured by the Hemochron Signature Eliteand the Abbott i-STAT: Agreement, Concordance, and Clinical Reliability

2019 ◽  
Author(s):  
Daniel Dirkmann ◽  
Elisabeth Nagy ◽  
Martin Walter Britten ◽  
Juergen Peters
Keyword(s):  
Cardiac Surgery ◽  
Linear Correlation ◽  
Point Of Care ◽  
Clotting Time ◽  
Cohen’S Kappa ◽  
Cohen's Kappa ◽  
Activated Clotting Time ◽  
Target Values ◽  
Heparin Anticoagulation ◽  
Parallel Measurements

Abstract Background: 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. However, concerns exist regarding reproducibility of ACT assays and comparability of devices. Methods: 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). 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. Measurements were compared between identical and different device types using linear regression, Bland-Altman analyses, and calculation of Cohen’s kappa coefficient. Results: Parallel i-STAT ACTs demonstrated a good linear correlation (r=0.985). Bias, as determined by Bland-Altman analysis, was low (-3.8s; 95% limits of agreement (LOA): -77.8 -70.2s), and Cohen’s Kappa demonstrated good agreement (kappa=0.809). Hemochron derived ACTs demonstrated worse linear correlation (r=0.782), larger bias with considerably broader LOA (-13.14s; 95%LOA:-316.3-290s), and lesser concordance between parallel assays (kappa=0.554). Although demonstrating a fair linear correlation (r=0.815), parallel measurements on different ACT-devices showed large bias (-20s; 95% LOA: -290-250s) and little concordance (kappa=0.368). Overall, disconcordant results according to clinically predefined target values were more frequent with the Hemochron than i-STAT. 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. Conclusion: Currently used ACT point-of-care devices cannot be used interchangeably. Furthermore, our data question the reliability of the Hemochron in assessing adequacy of heparin anticoagulation monitoring for CPB.

Venous or arterial samples for activated clotting time measurements: a systematic review

Perfusion ◽  
2020 ◽  
pp. 026765912096783
Author(s):  
Sashini Iddawela ◽  
Priti Swamy ◽  
Sajid Member ◽  
Amer Harky
Keyword(s):  
Systematic Review ◽  
Cardiac Surgery ◽  
Vascular Surgery ◽  
Cardiovascular Surgery ◽  
Cardiac Catheterisation ◽  
Clotting Time ◽  
Electronic Search ◽  
Activated Clotting Time ◽  
Cochrane Database ◽  
Assessment Techniques

Objective: The systematic review aims to investigate the effect of sampling source on activated clotting time (ACT) measurement within cardiovascular surgery and cardiac catheterisation. It also examines the evidence surrounding novel clot assessment techniques and associated sampling variation. Methods: A comprehensive electronic search was conducted using PubMed, MEDLINE, Scopus, Cochrane database, and Google Scholar until 20th June 2020. All studies reporting sampling source variability of ACT in cardiac surgery, vascular surgery and cardiac catheterisation were included. Results: Fourteen studies were included in the systematic review. Inconsistent reports of variability were seen in cardiac surgery and cardiac catheterisation. There were no studies directly examining ACT variability in vascular surgery. Novel clot assessment techniques have been validated in cardiac surgery, but measurements vary depending on sampling source. Conclusion: Sampling source should be kept consistent to facilitate effective haemostatic strategies. More research is needed regarding variability in vascular surgery and novel clot assessment techniques.

A comparative analysis of four activated clotting time measurement devices in cardiac surgery with cardiopulmonary bypass

Perfusion ◽  
2020 ◽  
pp. 026765912094935
Author(s):  
Han Li ◽  
Cyril Serrick ◽  
Vivek Rao ◽  
Paul M Yip
Keyword(s):  
Cardiac Surgery ◽  
Cardiopulmonary Bypass ◽  
System Analysis ◽  
Point Of Care ◽  
Measurement Range ◽  
Medical Decision ◽  
Clotting Time ◽  
Activated Clotting Time ◽  
Decision Points ◽  
Heparin Anticoagulation

Background: In cardiac surgery on cardiopulmonary bypass (CPB), heparin anticoagulation is monitored by point-of-care measurement of activated clotting time (ACT). The objective of this study was to compare four ACT systems in cardiac surgery in terms of their reproducibility, agreement and potential clinical impact at relevant medical decision points. Methods: The study included 40 cardiac surgery patients. Samples were taken at five time points before (T1), after heparinization for CPB (T2, T3, T4), and after heparin reversal (T5). The reproducibility, correlation, and differences in ACT values were assessed with two devices from each of the four ACT systems: Instrumentation Laboratory Hemochron Elite (Hmch), Medtronic HMS Plus (HMS), Abbott i-STAT, and Helena Abrazo. Subrange analyses were performed for low ACT values (results from T1, T5) and high ACT values (results from T2, T3, T4). Results: Within-system analysis showed strong linear correlation between paired measurements (R = 0.968-0.993). However, Hmch showed poorer reproducibility with highest proportion of values that exceed a difference of 10% and highest overall standard error of 74 seconds across the measurement range compared to that of the others (range 39-47 seconds, respectively). For inter-system comparison, using Hmch as reference, ACTs were strongly correlated as follows: HMS (R = 0.938), i-STAT (R = 0.911), and Abrazo (R = 0.911). Agreement analysis in the high ACT range showed HMS tended to have higher ACT values with +11% bias over Hmch, whereas i-STAT (–8% bias) and Abrazo (–13% bias) tended to underestimate. Post-protamine ACT results were dependent on device type where Hmch yielded highest post-protamine ACT (+13% higher than baseline) compared to –16% for HMS, –10% for iSTAT and 0% for Abrazo. Conclusions: Each device had individual reproducibility and biases, which may impact peri-operative heparin management. Careful validation must be undertaken when adopting a different method as decision limits would be affected. Clinicians should also be cautious using ACT as the only indicator for full heparin reversal.

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