الفهرس 
PHYSIOLOGY OF HEMOSTASIS AND COAGULATION MECHANISMOnly 14 pages are availabe for public view
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Abstract
D
espite continuous advances improving the safety of cardiac surgery, excessive bleeding requiring transfusion of blood components after cardiopulmonary bypass (PB) is still one of the main causes of post operative morbidity.
Excessive fibrinolysis and platelet dysfunction are the main causes of non surgical bleeding after open heart surgery.
Blood conservation techniques has been explored to reduce the need for blood transfusion: normovolemic hemodilution, intraoperative autotransfusion and the use of antifibrinolytic drugs.
There has been increased interest in tranexamic acid as an alternative to the more expensive drug aprotinin.
Tranexamic acid acts by formingg reversible complex with plasminogen and plasmin through the lysine binding sites, thus blocking interaction with the specific lysine residues of fibrin.
By inhibition of proteases and mediators of inflammation (e.g., kallikrein, plasmin, proinflammatory cytokines) aprotinin use results in significant attenuation of the systemic inflammatory response, fibrinolysis and thrombin generation. We chose a population of patients submitted to primary coronary artery grafting in order to determine if antifibrinolytic therapy is effective in a setting that usually does not involve excessive blood losses, homologous blood transfusion and trasylol on blood loss, homologous blood transfusion and coagulation patterns in cardiac surgery was investigated and compared.
Patients were divided into 3 groups: aprotinin treated group (25 patients), tranexamic acid treated group (25 patients) and control group (25 patients).
The aprotinin group was give 1x106 KIU at induction of anesthesia, 1 x 106 KIU added to priming volume of CPB and 250.000 KIU per hour as a continuous IV infusion till end of surgery, sensitivity test must be done before injection.
The tranexamic acid group was given 2 gram after the induction of anesthesia and before skin incision and another 2 gram was given after CPB.
To study the effect of these drugs, we measured the total blood loss until removal of chest drains, the amount of transfused homologous blood or blood products and the hematological parameters including hemoglobin, hematocrit, platelet count, prothormbin time, activated partial thromboplastin time and activated clotting time.
This study demonstrated that tranexamic acid and aprotinin had lower post operative blood loss compared with patients who received placebo and tranexamic acid is clinically as effective as aprotinin in reducing post operative blood loss and fibrinolysis and the need for transfusion of homologous blood products.
Tranexamic acid has a lower cost and a lower risk of adverse reactions (as renal dysfunction)