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Background: A minority of patients having cardiac procedures (15% to 20%) consume more than 80% of the blood products transfused at operation. Blood must be viewed as a scarce resource that carries risks and benefits. A careful review of available evidence can provide guidelines to allocate this valuable resource and improve patient outcomes., Methods: We reviewed all available published evidence related to blood conservation during cardiac operations, including randomized controlled trials, published observational information, and case reports. Conventional methods identified the level of evidence available for each of the blood conservation interventions. After considering the level of evidence, recommendations were made regarding each intervention using the American Heart Association/American College of Cardiology classification scheme., Results: Review of published reports identified a high-risk profile associated with increased postoperative blood transfusion. Six variables stand out as important indicators of risk: (1) advanced age, (2) low preoperative red blood cell volume (preoperative anemia or small body size), (3) preoperative antiplatelet or antithrombotic drugs, (4) reoperative or complex procedures, (5) emergency operations, and (6) noncardiac patient comorbidities. Careful review revealed preoperative and perioperative interventions that are likely to reduce bleeding and postoperative blood transfusion. Preoperative interventions that are likely to reduce blood transfusion include identification of high-risk patients who should receive all available preoperative and perioperative blood conservation interventions and limitation of antithrombotic drugs. Perioperative blood conservation interventions include use of antifibrinolytic drugs, selective use of off-pump coronary artery bypass graft surgery, routine use of a cell-saving device, and implementation of appropriate transfusion indications. An important intervention is application of a multimodality blood conservation program that is institution based, accepted by all health care providers, and that involves well thought out transfusion algorithms to guide transfusion decisions., Conclusions: Based on available evidence, institution-specific protocols should screen for high-risk patients, as blood conservation interventions are likely to be most productive for this high-risk subset. Available evidence-based blood conservation techniques include (1) drugs that increase preoperative blood volume (eg, erythropoietin) or decrease postoperative bleeding (eg, antifibrinolytics), (2) devices that conserve blood (eg, intraoperative blood salvage and blood sparing interventions), (3) interventions that protect the patient's own blood from the stress of operation (eg, autologous predonation and normovolemic hemodilution), (4) consensus, institution-specific blood transfusion algorithms supplemented with point-of-care testing, and most importantly, (5) a multimodality approach to blood conservation combining all of the above.

Background: Perfluorooctyl bromide is a biologically inert compound with short biologic retention and high oxygen solubility. The purpose of this study was to assess the effect of the perfluorocarbon emulsion, AF0144 (Perflubron, Alliance Pharmaceutical Corp, San Diego, CA), used in conjunction with acute normovolemic hemodilution on cerebral blood flow and cerebral emboli measurements during coronary artery bypass grafting with cardiopulmonary bypass., Methods: Thirty-six adult cardiac surgical patients were enrolled in a single-institution, randomized, controlled, single-blind dose escalation trial. Autologous whole blood was harvested from each patient to target an on-bypass hematocrit of 20% to 22%. Placebo, low dose (1.8 g/kg) or high dose (2.7 g/kg) AF0144 was administered. Transcranial Doppler ultrasonography was used to quantitate cerebral emboli and xenon-133 clearance was used to measure cerebral blood flow., Results: Cerebral blood flow was increased in both AF0144-treated groups compared with placebo (p = 0.006, low dose vs control; p = 0.036, high dose vs control). Numbers of cerebral emboli were greater in the high-dose AF0144-treated group versus control during the time periods from aortic cannulation through aortic cross-clamp placement (p = 0.026) and from aortic cross-clamp placement through cross-clamp removal (p = 0.008)., Conclusions: The perfluorocarbon emulsion, AF0144, increased cerebral blood flow during cardiopulmonary bypass. In addition, total cerebral emboli load during bypass was greater in patients receiving high-dose AF0144.

Background: The impact of alterable physiologic variables on neurologic outcome after coronary artery bypass grafting procedures is unknown. The purpose of this study was to determine whether minimum intraoperative hematocrit, maximum glucose concentration, or mean arterial pressure during cardiopulmonary bypass influences risk-adjusted neurologic outcome after coronary artery bypass grafting., Methods: Outcome data from 2,862 patients undergoing coronary artery bypass grafting were merged with intraoperative physiologic data. A preoperative stroke risk index was calculated for each patient. Variables found significant by univariate logistic regression were tested in a multivariable model to determine association with outcome., Results: The incidence of stroke or coma in the study population was 1.3%. After controlling for stroke risk and bypass time, only an index of low mean arterial pressure during bypass retained a significant inverse association with outcome (p = 0.0304)., Conclusions: This study found no evidence that glucose concentration or minimum hematocrit are associated with major adverse neurologic outcome. The association between lower pressure during bypass and decreased incidence of stroke or coma persisted in all risk groups. This points to mechanisms other than hypoperfusion as the primary cause of neurologic injury associated with cardiac surgery.

Background: Risk stratification schemes have been developed to predict outcome of coronary artery bypass grafting (CABG) procedures, which are predominately based upon unalterable preoperative patient characteristics. The purpose of this study was to determine if minimum intraoperative hematocrit, maximum glucose concentration, mean arterial pressure on cardiopulmonary bypass, or duration of bypass influence risk-adjusted in-hospital mortality after CABG., Methods: Outcome data from 2,862 CABG patients were merged with intraoperative physiologic data. A preoperative mortality risk index was calculated for each patient. Variables found significant (p<0.05) by univariate logistic regression were tested in a multiple variable model to determine risk-adjusted association with mortality., Results: Overall mortality rate was 1.85%. The preoperative risk index was significantly associated with mortality (p = 0.0001). No significant association was present between mortality and intraoperative variables. Preexisting hypertension was an independent predictor of mortality after controlling for risk index and bypass duration., Conclusions: Preexisting hypertension proved to be an independent predictor of mortality in our patient population. This study found no evidence to support the hypothesis that mean arterial pressure less than 50 mm Hg, lower hematocrit, or elevated glucose while on bypass increases in-hospital mortality.