Perfusion
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Comparative Study Clinical Trial Controlled Clinical Trial
Does heparin pretreatment affect the haemostatic system during and after cardiopulmonary bypass?
In this clinical pilot study, the influence of heparin pretreatment on the haemostatic system during and after cardiopulmonary bypass (CPB) was investigated. Thirteen patients scheduled for elective coronary artery bypass grafting (CABG) were divided into two groups: heparin pretreated (HP, n = 6) and non-heparin pretreated (NHP, n = 7). Blood samples were taken for measurements of plasma antithrombin-III (AT-III) activity, plasma heparin levels, activated clotting time with (HACT) and without (ACT) heparinase, whole blood platelet function, platelet count, thrombin-antithrombin-III complexes and D-dimer levels. ⋯ Furthermore, mediastinal blood loss showed a tendency to be lower in the HP group (p = 0.08). However, there was no difference in blood transfusion requirements between the groups. These data suggest that short-term heparin pretreatment affects the perioperative platelet responsiveness and attenuates the consumption of coagulation factors.
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Air microbubbles mostly occur unnoticed during cardiopulmonary bypass and are predominantly responsible for serious postoperative psychoneurological dysfunction. A dynamic bubble trap (DBT), which removes air microbubbles from the arterial blood, was tested in a clinical study. The aim was to evaluate the efficiency of microbubble removal under clinical conditions. ⋯ The bubbles are directed to the centre of the blood flow and are collected in the distal end of the DBT, from where they are returned to the cardiotomy reservoir. Doppler ultrasonography was used to detect the microbubbles before and after the DBT, and also the number of high-intensity transient signals (HITS) in the right and left middle cerebral artery during extracorporeal circulation. A significant reduction of microbubbles in the arterial line (3,990 before DBT, 537 after, p < 0.001) and HITS in the brain (51 in the DBT group, 77 in the placebo group, p = 0.04) was measured.
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Comparative Study
Inflammo-coagulatory response, extrinsic pathway thrombin generation and a new theory of activated clotting time interpretation.
When blood is subjected to contact with foreign surfaces, as during cardiopulmonary bypass (CPB), the whole body inflammatory response is initiated, resulting in the expression of procoagulant molecules on the vascular endothelium and white blood cells. These surface bound procoagulants participate in the extrinsic coagulation pathway. It appears that the primary source of thrombin generation during CPB is due to extrinsic pathway activation. ⋯ Anti-inflammatory agents which suppress or inhibit the extrinsic pathway, such as aprotinin, result in decreased thrombin generation. As thrombin generation decreases, the ACT-heparin dose response curve is warped, resulting in a dose response curve resembling a PTT-heparin dose response curve. We can no longer assume that the disproportionate rise in the ACT relative to the [HEP - ATIII] when aprotinin is used as indicative of failure of the ACT to provide a credible indication of anticoagulation.