Autotransfusion in Aortic Reconstruction

Significant positive advances have been made over the past half century in both the safety and efficacy of open aortic reconstruction for the treatment of either aneurysmal or occlusive diseases of the aorta. These operations are associated at times with estimated blood loss sufficient to require blood replacement therapy to restore blood volume and homeostasis. Autotransfusion of blood or blood components is one method to successfully achieve these goals.

Reports from various vascular surgery services have confirmed the safety, cost-effectiveness, and benefits of intraoperative blood salvage with autotransfusion. This particular strategy is used to reduce the volume of donated homologous blood transfusion as well. Avoiding the small but irreducible transmitted infectious complications inherent in homologous transfusion favors autotransfusion. Additional advantages favoring autologous transfusion compared to homologous transfusion include avoiding transfusion mismatch and compatibility reactions, as well as recipient isoimmunization and immune suppression. Additionally, the problem of stored homologous blood having reduced effective oxygen-carrying capacity is avoided.

Whereas surgeons have focused on the practical utility of intraoperative blood salvage for the individual patient, others have emphasized the need for a comprehensive blood transfusion program to minimize the patient’s exposure to homologous blood and to add an autologous blood component to the blood bank’s overall resource pool. In vascular surgery, autotransfusion has been demonstrated to be most effective in support of abdominal aortic aneurysm (AAA) operations. Complementary elements for consideration in a comprehensive blood transfusion program in aortic operations include autologous preoperative blood deposit for elective operations, routine use of intraoperative blood salvage in elective and emergency operations, and adherence to patient-specific indications for transfusions. Careful adherence to optimal operative hemostatic technique is indispensable in aortic operations, particularly from the standpoint of minimizing the need for any transfusions.

Autologous Preoperative Deposit

Autologous preoperative deposit is typically undertaken by blood bank personnel following established protocols and in response to the surgeon’s specific request. It is applicable when there is both a likely need for perioperative blood transfusions and sufficient lead time to allow repeated outpatient phlebotomies. Patients whose cardiac reserve is limited owing to coronary or valvular heart disease should undergo phlebotomy only after consideration of the possible adverse cardiac effects of anemia and the compensatory blood volume shifts associated with these phlebotomies. Patients considered for aortic operations may be scheduled for cardiac stress testing, and the results of this evaluation could guide the timing to predeposit blood, as well as the optimal number of units to be collected.

The blood bank standards requiring volunteers to wait at least 2 months between donor phlebotomies are often relaxed for patients making autologous predeposits. In good-risk patients, 4 to 7 days may be sufficient between phlebotomies, timing the final donation for approximately 3 days before the planned procedure. Oral iron supplements are administered throughout the predeposit period. Erythropoietin as an additional adjunct for these autologous donors does not appear to be justified for routine use. The hemogram is monitored to keep the patient’s preoperative hemoglobin at least 10 g/dL and hematocrit no less than 30%.

The age guidelines for autologous predeposit are less stringent than those for volunteer donors for homologous blood transfusion, maintaining autologous predeposit as a practicality in the aged vascular surgery population. Prudence dictates that it would be wise to guard against an implied or stated guarantee that autologous predeposit would protect against the need for any homologous blood or blood products. Rather, autologous predeposit is an effective method to lower the likelihood that homologous blood may be needed.

When predeposited blood exceeds the blood volume needed for transfusion during the perioperative period, we do not infuse the remaining predeposited blood simply because it is available. An unindicated blood transfusion, albeit autologous, carries some unnecessary risks and costs. There is the risk of bacterial contamination in any stored blood. Although the possibility is very remote, a potentially disastrous labeling error causing a mismatched transfusion can occur. These problems can be avoided altogether if unindicated transfusions, even autologous, remain ungiven. Unused autologous blood is either frozen for future use or discarded. Generally, unused units are not released to the general resource pool for use as donated homologous units.

When autologous preoperative blood deposit is employed, most patients scheduled for elective AAA and thoracoabdominal aortic aneurysm repairs predeposit 2 to 4 units of autologous blood. However, recognized disadvantages exist for autologous blood donations. There is significant increase in cost with the use of preoperative blood donation. Decision-analysis models to assess the cost-effectiveness of the use of predonated autologous blood over allogeneic blood found a tremendous increase in cost for the use of predonated autologous blood but little expected health benefit.

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