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Ann Thorac Surg 1996;62:1885-1886
© 1996 The Society of Thoracic Surgeons
New York Hospital-Cornell Medical Center, 525 E 68th St, F-2103, New York Ny 10021
To the Editor:
We would like to comment on the recent article by Magovern and associates [1] and the accompanying editorial by Goodnough [2] regarding the definition of a predictive score for transfusion requirement after an open heart operation. As noted by Goodnough, Magovern and associates have conclusively validated a transfusion risk score that includes "the usual suspects," including age and red blood cell mass, as well as a number of unanticipated risk factors, including poor ejection fraction and other co-morbidities. Postoperative chest tube output and the transfusion of coagulation factors were not examined in this report. We and others [3, 4] have demonstrated that postoperative chest tube output is a predictor of total homologous transfusions that is independent of the risk factors cited by Magovern and associates. We emphasize that the transfusion of coagulation factors, which is predicted by chest tube output, contributes significantly to the total donor exposure risk, and should be included in studies assessing transfusion risk. In this regard, we believe that blood conservation strategies that rely upon single-component therapy, such as the isolated application of hemostatic agents or techniques such as autologous donation, will not successfully eliminate homologous transfusion because they do not adequately address all the independent transfusion risk factors.
We have reported on our experience with a "maximal" blood conservation program in 50 Jehovah's Witness (JW) patients [5], and have applied a stratified program applying various components of this strategy on a risk-related basis in 100 consecutive coronary bypass patients treated without transfusion. In constructing these programs, we have emphasized the need to comprehensively address the risk factors for transfusion, including both low preoperative red blood cell mass and postoperative blood loss. In our most recent review of open heart procedures in the Jehovah's Witness population, procedures performed included both coronary artery bypass grafting (n = 30) and more complex operations (n = 20), including reoperations, multiple valve replacements, and congenital heart repairs. The blood conservation program employed in these patients included the use of (1) high-dose erythropoietin (800 U/kg load, 500 U/kg every other day), (2) aprotinin (full Hammersmith regimen), (3) retrograde autologous priming of the cardiopulmonary bypass circuit, (4) "maximal"-volume intraoperative autologous blood donation, (4) "low-prime" cardiopulmonary bypass, (5) exclusive intraoperative cell salvage, and (6) continuous shed mediastinal blood reinfusion. Despite the absence of transfusion, the mean discharge hematocrit in the JW patients was greater than 30%, and there was no anemia-related mortality in this group. The overall 30-day mortality for the JW group was 2%. A subset analysis was performed between the 30 first-time coronary bypass JW patients and a matched control group. The chest tube output in the JW-coronary patients was less than 40% of that for control patients at all measured time points measured after operation (p < 0.01). Postoperative hematocrits in the JW-coronary group were greater than those for the control group, despite the absence of red blood cell transfusion and despite a significantly lower admission hematocrit and red blood cell mass in the JW group. The average length of stay and ancillary cost of the two groups were equivalent. These results suggest that even complex open heart operations can be performed without homologous transfusion by optimally applying currently available blood conservation techniques.
In our risk-stratified program, application of various components of this multimodality conservation program allowed the performance of 100 consecutive coronary bypass operations without any homologous transfusions, compared with a transfusion rate of 38% in matched controls. We would therefore highlight the editorial comments of Goodnough regarding the importance of using the transfusion risk score of Magovern and associates to properly stratify patients into an appropriate blood conservation program. More generalized application of the conservation protocols such as that which we have outlined above may in this manner increasingly allow "bloodless" cardiac operations in all patients.
References
Allegheny-Singer Research Institute, 320 E North Ave, Pittsburgh, Pa 15212-4772
To the Editor:
Doctors Rosengart and Krieger correctly point out that chest tube drainage is an independent predictor of subsequent transfusion. This has been shown in several reports and is an important factor. Our article analyzed only preoperative data to define a risk score that predicted the need for transfusion during or after operation. The concept of this analysis was to stratify patients into low-, medium-, and high-risk groups before operation so that targeted strategies for blood conservation could be developed. The maximal blood conservation program outlined by Rosengart and Krieger addresses all the factors that contribute to the need for transfusion, including preoperative, intraoperative, and postoperative events. This protocol has been effective at reducing transfusion, but it seems to be an aggressive approach. Blood conservation is certainly an important consideration, but it still needs to be justified on a cost basis. The incremental cost of all of the interventions outlined may exceed the cost of blood transfusion, especially if applied to all patients, most of whom are not likely to require transfusion. A logical approach would be to focus the expensive portions of the protocol (erythropoietin, aprotinin, use of a cell-saving device) on those patients judged to be at high risk for transfusion, and to make fewer interventions on those with a low risk. This would make this aggressive protocol more feasible from a cost perspective. My colleagues and I agree that the need for transfusion can be dramatically reduced by implementing currently available strategies. This could be realized in a cost-effective manner by combining blood conservation methods with a risk-stratified protocol for defining highand low-risk patients before operation.
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