Perfusion
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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.
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Randomized Controlled Trial Comparative Study Clinical Trial
A clinical evaluation of platelet function, haemolysis and oxygen transfer during cardiopulmonary bypass comparing the Quantum HF-6700 to the HF-5700 hollow fibre membrane oxygenator.
The continued improvement of oxygenators is an important aspect of patient safety during cardiopulmonary bypass (CPB). The purpose of this study was to compare the Bard William Harvey HF-5700 oxygenator to the upgraded Bard Quantum HF-6700, which has recently been introduced into clinical practice. No clinical evaluation of this device has been published to date. ⋯ Samples were obtained at the start of CPB, at 30 min, 60 min, at the end of CPB and at 1 h following termination of CPB. No significant differences between the two groups were found in oxygen transfer, haemolysis (plasma haptoglobin levels) or platelet function (a novel platelet activating factor (PAF)-induced platelet activation test) at any of the time points during CPB. It was concluded that the Quantum HF-6700 matches the HF-5700 for the parameters studied, whilst having the advantage of requiring a smaller priming volume.
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Comparative Study
Preservation of collagen-induced whole blood platelet aggregation by tranexamic acid therapy in primary cardiac valve surgery.
Haemostatic disorder is one of the most common complications following cardiac surgery with cardiopulmonary bypass (CPB). Tranexamic acid reduces blood loss and allogeneic blood transfusion requirement in cardiac surgery. It had been thought that tranexamic acid inhibited fibrinolysis alone following CPB. ⋯ Fibrinolysis following CPB was reduced significantly in the tranexamic acid group. Following protamine administration, the reduction of collagen-induced whole blood platelet aggregation was mitigated significantly in the tranexamic acid group compared with the control group (36% reduction in the tranexamic acid group vs 58% in the control group; p = 0.011), although platelet counts did not differ between the two groups. In conclusion, tranexamic acid not only inhibits fibrinolysis directly, but also may preserve platelet function following CPB.
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Optimal management of acute pulmonary embolism remains controversial, despite advances in thrombolytic therapy. Haemodynamic instability and, in particular, right ventricular dysfunction is associated with poor outcomes. ⋯ We present two cases in which percutaneous cardiopulmonary support (PCPS) was used as an adjunct to thrombolytic therapy for progressive circulatory collapse secondary to massive acute pulmonary embolism. This experience suggests that PCPS may offer an attractive option for a condition which continues to carry significant morbidity and mortality.
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The serine protease inhibitor antithrombin-III (AT-III) is the principal in vivo inhibitor of blood coagulation, inactivating mainly thrombin, but also other serine proteases. Binding of AT-III to heparin dramatically increases its inhibitory effect. AT-III deficiency during cardiopulmonary bypass (CPB) can lead to insufficient anticoagulation which cannot be treated by higher doses of heparin. ⋯ Postoperatively, there was continued blood loss, which necessitated the administration of whole blood and eventually re-exploration. The case presented illustrates an uneventful treatment of a patient with a hereditary AT-III deficiency undergoing CPB. In spite of an uneventful treatment with AT-III pre-CPB, administration of prophylactic AT-III concentrate after surgery should be considered with caution, as this might increase the postoperative morbidity.