Evaluation of the Effect of Dextran Sulphate on Anti-Xa Activities Measured

Overview

The measurement of anti-Xa activity is classically used for the dose adjustement of unfractionated heparin (UFH) treatment and to monitor reversal of UFH by protamine during cardiac surgery with cardiopulmonary bypass (CPB). Three categories of reagents are currently available in France for the measurement of anti-Xa activity: antithrombin-containing reagents (very little used), antithrombin-free reagents and antithrombin-free reagents with dextran sulphate. Significant differences in anti-Xa results based on the reagents used were described, particularly after protamine neutralization in CPB. Indeed, dextran sulphate, contained in some reagents, could dissociate the heparin/protamine complex contributing to the higher levels of anti-Xa with these reagents. The differences observed in these patients are likely related to the presence of platelet factor 4 (PF4) in the samples from either PF4 present in vivo in patients or released in vitro after blood collection. These differences may lead to different therapeutic attitudes, including the re-administration of protamine to neutralize heparin at the end of CBP

Any hospitalized patient receiving UFH in the intensive, cardiac surgery and medicine departments of the participating centres will be offered the study by investigator. It will be included in the study after validation of the selection criteria and after collecting its non-opposition. This participation will not change the medical care of the participants. Patients will be divided into four groups: * Group 1: patients with cardiac surgery with CBP. Blood samples in the operating room, 5 to 10 minutes after neutralization of heparin by protamine. * Group 2: patients who had cardiac surgery with CBP, between day 1 and day 5 after surgery. * Group 3: hospitalized patients in intensive care unit, including patients on extracorporeal life support (ECLS). Group 4: patients hospitalized in a medical non-intensive care ward. The response to heparin treatment varies considerably depending on the clinical situation. The results found in one indication are not transposable to another indication. The 4 patient groups will provide a comprehensive response to situations in which heparin is used. For each patient, during the usual follow-up of anti-Xa activity, and only once per patient, 3 to 4 additional blood tubes - 1 citrate tube (0.109 M) of 5 mL or 2 citrate tubes of 3 mL and 2 tubes CTAD (Citrate-Theophylline, Adenosine, Dipyrioledam) of 3 mL - will be taken during a blood test carried out in common practice. Thus, no additional invasive gestures are added by this search. CTAD contains, in addition to citrate, a platelet activation inhibitor and thus limits the in-vitro activation of platelets and thus the release of PF4. Blood samples will be handle according to the usual procedures of each centre. All plasma will be aliquoted and stored at -80oC, until the end of inclusions in the hematology laboratories of each center. At the end of the inclusion period, the aliquotes will be sent to the hematology laboratories of the Necker University Hospital and the University Hospital of Rennes for centralized testing. The measurement of anti-Xa activities will be carried out on frozen-defrosted citrate and CTAD plasma with with 4 reagents: * STA-Liquid anti-Xa (STAGO) (not containing dextran) * Biophen Heparin LRT (Hyphen) (containing dextran) * Berichrom (Siemens) with dextran * Berichrom (Siemens) without dextran The dosage of platelet factor 4 and beta-TG will be performed on frozen-defrosted plasma with CTAD with asserachrom PF4 and Asserachrom beta-TG (Diagnostica Stago) kits.