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In response to - Reducing allogenic transfusion in cardiac surgery: a randomized double-blind placeb
- Praveen Kumar Neema, Manikandan S, Rathod RC (23 September 2005)
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Reducing allogeneic transfusion in cardiac surgery: a randomized double-blind placebo-controlled tri
- Deepak K. Tempe (30 April 2005)
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Praveen Kumar Neema, Anaesthesiologist Sree Chitra Tirunal Institute for Medical Sciences & Technology, Trivandrum, India, Manikandan S, Rathod RC
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Editor – We read with interest the article - Reducing allogenic transfusion in cardiac surgery: a randomized double-blind placebo- controlled trial of antifibrinolytic therapies used in addition to intraoperative cell salvage 1 and we congratulate the authors for their study that showed efficacy of aprotinin in addition to intra-operative cell salvage in reducing patient exposure to any allogeneic transfusion during first time cardiac surgery. Indeed there is a need to reduce allogeneic transfusions because of various reasons. Among various techniques in use, aprotinin is the most effective intraoperative pharmacological regimen to reduce perioperative allogeneic blood transfusion. However, we have difference of opinion on the methodology of anticoagulation. The authors administered heparin 400 IU/kg to all the study patients to achieve a celite-activated clotting time of greater than 800 seconds before CPB and if ACT was not achieved, further boluses of heparin 100 IU/kg body weight were administered. Presumably, the targeted celite-ACT of > 800 seconds was in view of aprotinin administration. However, this approach would have resulted in overdosing of heparin and excess anticoagulation in control group and Traneximic acid group patients and is likely to put these patients at a disadvantage. Gravlee et al reported that maintaining ACT at 300-350 seconds requires less heparin, and may be associated with less bleeding after operation.2 The current anticoagulation practice is to administer 300 IU/kg body weight of heparin and to keep ACT at > 400 seconds or > 480 seconds throughout the conduct of CPB.3 Gravlee et al further states that there is no advantage in keeping ACT at or above 600 seconds. We believe that it would have been more appropriate if anticoagulation was monitored by Kaolin ACT and the targeted kaolin ACT was kept at > 400 or > 480 seconds. In presence of aprotinin, Kaolin-ACT is more dependable and gives ACT’s similar to those without aprotinin in vitro and during CPB.4 Reference: 1. Diprose P, Herbertson MJ, O’Shaughnessy D, Deakin CD, Gill RS: Reducing allogenic transfusion in cardiac surgery: a randomized double-blind placebo-controlled trial of antifibrinolytic therapies used in addition to intraoperative cell salvage. Br J Anaesth 2005; 94:271-8 2. Gravlee GP, Haddon WS, Rothberger HK, Mills SA, Roger AT, Bean VE, et al: Heparin dosing and monitoring for cardiopulmonary bypass. J Thorac Cardiovasc Surg 1990:99:518 3. Lesserson LS, Gravlee GP: Anticoagulation for cardiopulmonary bypass, in Gravlee GP (ed) Cardiopulmonary bypass Principles and Practice, Philadelphia, pa, Lippincott Williams and Wilkins 2000, pp 435-472 4. Wang JS, Lin CY, Hung WT, Karp RB: Monitoring of heparin induced anticoagulation with kaolin activated clotting time in cardiac surgical patients treated with aprotinin. Anesthesiology 1992; 77:1080 Conflict of Interest:None declared |
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Deepak K. Tempe Department of Anaesthesiology and Intensive Care, G.B. Pant Hospital, New Delhi
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Editor: I welcome the study by Diprose and colleagues1 comparing aprotinin and tranexamic acid in patients undergoing first time cardiac surgery. The authors have nicely demonstrated that aprotinin used in addition to intraoperative cell salvage is the most efficacious pharmacological therapy for reducing patient exposure to allogeneic transfusion. One of the most important factors in making blood conservation a reality during cardiac surgery, is the acceptance of normovolaemic haemodilution. However, the transfusion trigger during cardiac surgery continues to remain controversial.2 We have earlier shown that cell saver in combination with intra-operative autologous blood donation decreased transfusion requirements in a group of patients with a mean body weight of 45 kg.3 Seventy eight percent of these patients undergoing valve surgery did not require any blood transfusion. This was possible due to acceptance of a haematocrit of 15% on bypass and 25% after bypass. We have also compared cell saver and low dose aprotinin in patients undergoing valve surgery and found them to be comparable in terms of reducing blood transfusion requirement.4 Aprotinin helps by decreasing the postoperative bleeding, whereas the cell saver helps by making the patient’s own blood available for transfusion. While these blood conservation strategies can substantially decrease the transfusion of allogeneic red blood cells and coagulation products, the clinical application of these reports should be carefully chosen. The important concerns related to the use of aprotinin include graft occlusion in patients undergoing coronary artery bypass grafting (CABG), anaphylactic reaction, and risk of impaired renal function. The risk of graft thrombosis is real and well documented.5,6 As regards cell saver, there is some concern about transfusion of cytokines through autologous shed blood.7 In addition, these are expensive techniques and the use of cell saver also requires services of a trained technician. It seems that preoperative risk stratification is essential to allow for more rational resource allocation of costly blood conservation strategies and blood bank resources. One such model has been recently developed.8 According to this model, independent predictors of blood product usage in CABG patients were preoperative haemoglobin 12.0 gm or less, emergent operation, renal failure, female sex, age 70 years or older, left ventricular ejection fraction 0.40 or less, redo procedure and low body surface area. Since, with careful, surgery, homologous blood transfusion can be avoided in most patients undergoing primary CABG, we prefer to use aprotinin only in patients who have increased risk of bleeding such as those on aspirin or thrombolytic therapy, redo surgery or those having rare blood type. A combined approach, as described by Diprose and colleagues can also be considered in these patients. Dr. Deepak K. Tempe Director-Professor and Head Department of Anaesthesiology and Intensive Care G.B. Pant Hosptial (University of Delhi) New Delhi. 110002 E mail: tempedeepak@hotmail.com 1 Diprose P, Herbertson MJ, O’Shaughnessy, Deakin CD, Gill RS. Reducing allogeneic transfusion in cardiac surgery: a randomized double- blind placebo-controlled trial of antifibrinolytic therapies used in addition to intra-operative cell salvage. Br J Anaesth 2005;94:271-8 2 Hebert PC, Fergusson D. Do transfusions get to the heart of the matter? JAMA 2004;292:1610-2 3Tempe D, Bajwa R, Cooper A, et al. Blood conservation in small adults undergoing valve surgery. J Cardiothorac Vasc Anesth 1996;10:502-6 4Tempe DK, Banerjee A, Virmani S, et al. Comparison of the effects of a cell saver and low-dose aprotinin on blood loss and homologous blood usage in patients undergoing valve surgery. J Cardiothorac Vasc Anesth 2001;15:326-30 5 Alvarez JM, Chandraratna H, Newman MA, et al. Intraoperative coronary thrombosis in association with low dose aprotinin therapy. J Cardiothorac Vasc Anesth 1999;13:1999- 6 Alderman EL, Levy JH, Rich JB, et al. Analyses of coronary graft patency after aprotinin use: results from the International Multicenter Aprotinin Graft Patency Experience (IMAGE) trial. J Thorac Cardiovasc Surg 1998;116:716-30 7 Arnestad JP, Bengtsson A, Bengtson JP, Tylman M, Redl H, Schlag G. Formation of cytokines by retransfusion of shed whole blood. Br J Anaesth 1994;72:422-5 8 Arora RC, Legare JF, Buth KJ, Sullivan JA, Hirsch GM. Identifying patients at risk of intraoperative and postoperative transfusion in isolated CABG: toward selective conservation strategies. Ann Thorac Surg 2004;78:1537-54 Conflict of Interest:None declared |
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