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Natural and synthetic antifibrinolytics in cardiac surgery
1Department of Anaesthesia, University of Montreal, Quebec.
Insights
Antifibrinolytic drugs like tranexamic acid can reduce bleeding and transfusions after heart surgery. However, their use should complement, not replace, careful surgical and anesthetic management.
Area of Science:
- Cardiovascular Surgery
- Anesthesiology
- Pharmacology
Background:
- Cardiopulmonary bypass (CPB) can induce hemostatic defects, increasing bleeding risks.
- Antifibrinolytic agents are explored to mitigate bleeding and transfusion needs post-CPB.
- The precise mechanisms of action for antifibrinolytics in CPB remain challenging to define.
Purpose of the Study:
- To evaluate the efficacy of antifibrinolytics in reducing bleeding and transfusion requirements after cardiac surgery.
- To discuss the clinical application and economic considerations of using antifibrinolytics.
- To outline current practices for antifibrinolytic use at the Montreal Heart Institute.
Main Methods:
- Review of antifibrinolytic agents including aprotinin, tranexamic acid, and sigma-aminocaproic acid.
- Analysis of their effectiveness in preventing or treating excessive bleeding during cardiac surgery.
- Examination of current institutional protocols for antifibrinolytic administration.
Main Results:
- All evaluated antifibrinolytics appear effective in managing bleeding associated with cardiac surgery.
- Current protocols at Montreal Heart Institute involve selective prophylactic use of sigma-aminocaproic acid for specific patient groups.
- Aprotinin's use is under investigation for both prophylactic and therapeutic applications.
Conclusions:
- Antifibrinolytics are valuable adjuncts but do not replace meticulous surgical and anesthetic care.
- Appropriate transfusion practices are crucial alongside antifibrinolytic therapy.
- Further comprehensive data is needed to establish definitive conclusions on optimal antifibrinolytic use and economic impact.
Abstract:
In an effort to reduce morbidity associated with transfusion of blood products, the use of antifibrinolytics to decrease bleeding and transfusions after cardiopulmonary bypass (CPB) is receiving widespread attention. The predominant haemostatic defect induced by CPB and, therefore, the mechanisms by which natural (aprotinin) or synthetic antifibrinolytics (sigma-amino-caproic acid, tranexamic acid) exert their effects have been difficult to define. Nonetheless, all three substances appear to be effective in the treatment or in the prevention of excessive bleeding associated with cardiac surgery. However, the administration of these drugs should not attempt to replace meticulous surgical and anaesthetic care. In particular, the importance of an appropriate transfusion practice cannot be overemphasized. The efficient use of these, sometimes expensive, drugs must take into account not only the initial cost, but also the short- and long-term economic consequences for the health care provider of using, or not using, a given medication. Unfortunately, the comprehensive data on which authoritative conclusions may be reached are not yet available. Pending availability of these data, the present use of antifibrinolytics at the Montreal Heart Institute is the following: (1) patients undergoing elective primary myocardial revascularization or valve surgery do not receive prophylactic antifibrinolytics; (2) patients undergoing repeat myocardial revascularization, repeat valve surgery, or primary or repeat combined procedures, receive prophylactic sigma-aminocaproic acid; (3) sigma-aminocaproic acid may be used to treat excessive chest drainage in the postoperative period; (4) the prophylactic and the therapeutic uses of low doses of aprotinin are currently under investigation.