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Ann Thorac Surg 1996;61:1135
© 1996 The Society of Thoracic Surgeons
DR SAFUH ATTAR (Baltimore, MD): I enjoyed Dr Katsaros' presentation regarding tranexamic acid in cardiac operations. I disagree with quite a few points. The first is that the basic study was done on patients who did not require any medication in the first place. Patients undergoing coronary artery bypass grafting for the first time very rarely require antifibrinolytic therapy, because the blood loss is minimal; it runs between 200 and 400 mL. So if you reduce it by 20% to 30%, you save 100 mL. I do not think that is really a reason to give tranexamic acid in coronary artery bypass grafting performed for the first time.
Now, the second thing is that you are treating bleeding, a complication, without knowing its cause. You do not treat pneumonia with antibiotics without knowing exactly the specific organism causing it, culturing it, determining its sensitivity to antibiotics, and then treating it. In these cases, we assume that all of the patients have all the complications of platelet dysfunction, deficiency of the extrinsic and intrinsic coagulation factors, platelet aggregation deficiency, fibrinolysis, all the problems encountered with cardiopulmonary bypass. In fact, this is not the case. Each case of bleeding has to be studied intraoperatively to determine what is the cause of bleeding and then treat it accordingly. This is the basis of medicine: find the cause and treat it, whereas we surgeons take the shortcut and treat all patients the same. There have been a lot of studies similar to the one presented this morning that demonstrate significant improvement in blood loss, but the blood loss is not the question. The fact that you have given them blood transfusions and blood products also indicates that you are very liberal in your use of blood, because the American Association of Blood Banks has established that the trigger point for blood transfusions is no more than 8 to 9 g/dL. When patients have about 10 or 11 g/dL of hemoglobin postoperatively there is no need for transfusions.
The point I want to make is that I think we need to do more intraoperative testing such as thromboelastography of the coagulation and fibrinolytic studies, platelet count, and platelet quality. You can determine the intrinsic and extrinsic clotting factors by measuring prothrombin time, partial thromboplastin time, and fibrinolysis by fibrinogen degradation products. These results are obtained immediately in the operating room, and then one can treat the patient accordingly.
This is the reason we still see a lot of studies that have questionable usefulness. Tranexamic acid and aminocaproic acid, unfortunately, are used with certain potential complications. You may not have had a serious complication; however, there have been reported cases of acute renal failure because of thrombosis of the renal artery after aminocaproic acid and tranexamic acid treatment. Therefore, I stress that when you use these substances the patient should have good renal output. Do not use any drugs if they are not indicated, and if they are indicated, try to minimize their damage.
DR KATSAROS: There are many points that were brought out. The first one was that no medication is required because in a first-time operation there is not much blood loss. One of the reasons we undertook this study was to see if the first-timer would benefit from routine use. And the bottom line is that the control group had 55 units of platelets used as opposed to the tranexamic acid group, which had 17 units. We used less fresh-frozen plasma: 29 units for the controls and 5 for the patients in the tranexamic study group. We also used less platelets. So, we indeed did use less blood products.
As far as not knowing the mechanism of postmediastinal bleeding, it is a very complex problem, and I think many authors would cite platelet dysfunction as a major component. Fibrinolysis can occur 15% to 20% of the time and can be considered a significant cause of mediastinal bleeding, but most of it is due to platelet dysfunction. This drug does affect platelet dysfunction; it preserves platelet function by preventing degranulation.
Our trigger point was a hemoglobin level of 7 g/dL, which is quite low. A point was mentioned about the thromboelastogram. The thromboelastogram takes quite a long time, 1
hours, to determine if there is fibrinolysis. Expensive platelet tests have not been shown to be predictive of postbypass bleeding.
Large series have failed to show thrombotic complications with tranexamic acid. I refer to Bekassy and associates [], who did not report any thrombotic complications in a review of 3,000 women taking the drug for a long time. There is also the combined experience, in the bypass population it is more than 1,000 patients by now, and none of these series have shown statistical significance in terms of neurologic or thrombotic complications.
Related Article
Ann. Thorac. Surg. 1996 61: 1131-1135.
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