Surgical procedures account for the transfusion of almost 15 million units of packed red blood cells (RBCs) every year in the United States. “There has been intense interest in blood conservation and minimizing blood transfusion over the past several years, but the number of annual transfusions is increasing,” says Victor A. Ferraris, MD, PhD. “At the same time, the blood donor pool has stabilized or slightly decreased.” Perioperative bleeding that requires RBC transfusion is especially common during cardiac operations, which consume as much as 10% to 15% of the nation’s blood supply. Evidence suggests that this figure is rising, largely because of the increasing complexity of cardiac surgical procedures.
“An important part of blood resource management is recognizing patients’ risk of bleeding and subsequent blood transfusion.”
In the March 2011 Annals of Thoracic Surgery, the Society of Thoracic Surgeons and the Society of Cardiovascular Anesthesiologists published an update to their 2007 blood conservation clinical practice guidelines. Certain features of blood conservation and management of blood resources have been updated or added. The guidelines provide updates in the preoperative management of dual antiplatelet treatment, pharmacotherapy to increase RBC volume or to reduce blood loss, and the use of blood derivatives. They also provide updated strategies to manage blood salvage, information on the use of minimally invasive procedures to reduce perioperative bleeding and need for blood transfusion, and strategies for blood conservation associated with extracorporeal membrane oxygenation and cardiopulmonary perfusion. The use of topical agents for hemostasis and the optimal usefulness of team interventions in blood management are also discussed in the guideline update.
Emphasizing Preoperative Risk Assessments
The Society of Thoracic Surgeons Blood Conservation Guideline Task Force noted that preoperative risk assessment is a necessary starting point for RBC conservation (Table 1). “Patients undergoing cardiac procedures have varying risk of bleeding or blood transfusion,” explains Dr. Ferraris, who was the chair of the guideline task force. “An important part of blood resource management is recognizing patients’ risk of bleeding and subsequent blood transfusion.” Three important preoperative risk factors have been linked to bleeding and blood transfusion: age of 70 or older; low RBC volume from preoperative anemia, small body size, or both; and urgent or complex operations associated with prolonged operating times and non-CABG procedures. “Patients at highest risk for bleeding are most likely to benefit from aggressive blood management practices,” adds Dr. Ferraris. “That’s because the highest-risk patients consume the majority of blood resources.”
Changes to Previous Blood Conservation Guidelines
According to Dr. Ferraris, several major changes or additions were made to the 2007 guidelines for blood conservation before, during, and after surgery. Prior to surgery, clinicians are recommended to take measures that reduce hemodilution and conserve preoperative patient red cell volume (Table 2). Antiplatelet and anticoagulant drug therapy should be identified and managed prior to surgery. Drugs used for intraoperative blood management include lysine analogs to decrease total blood loss and reduce the number of patients needing blood transfusion during cardiac procedures. “The risks of aprotinin outweigh the benefits,” Dr. Ferraris says. “Therefore, these drugs are not indicated for routine blood conservation.” The use of blood derivatives may facilitate blood management in patients with serious bleeding with multiple or single coagulation factor deficiencies, and safer fractionated products are not available. Intraoperative platelet plasmapheresis may help conserve blood as part of a multimodality program in high-risk patients if an adequate platelet yield can be reliably obtained.
To manage intractable nonsurgical bleeding after cardiac procedures using cardiopulmonary bypass, use of recombinant factor VIIa concentrate may be considered. Several blood salvage interventions may be used in high-risk patients, and adjunctive topical interventions (eg, topical hemostatic agents or antifibrinolytic agents poured in the surgical wound) may be useful to supplement local hemostasis achieved by good operative techniques.
Blood Conservation Management for the Future
An important facet of blood conservation is the management of blood resources, according to Dr. Ferraris. “To make important strides, a multidisciplinary team made up of a broad base of stakeholders should be established so that blood conservation in surgery is promoted safely and appropriately. The Society of Thoracic Surgeons and the Society of Cardiovascular Anesthesiologists will revisit this updated set of guidelines in the future as more research and data emerge. The hope is that, in the coming years, a consistent transfusion algorithm will be defined. Such an algorithm will need to be agreed upon by all team members. Equally important will be the implementation of point-of-care testing to guide transfusion decisions.”
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