Need For Allogeneic Transfusion Research Articles

Comparison of the effects of aprotinin and tranexamic acid on blood loss and red blood cell transfusion requirements during the late stages of liver transplantation

During liver transplantation (LT), profound activation of the fibrinolytic system can contribute significantly to perioperative bleeding. Prophylactic administration of antifibrinolytic agents has been shown to reduce blood loss and the need for allogeneic transfusion in these conditions. This prospective randomized trial included 51 cirrhotic patients undergoing LT. Patients were randomly assigned to receive either 280 mg of aprotinin (AP) followed by 70 mg per hour or 40 mg per kg tranexamic acid (TA) followed by 40 mg per kg per hour, administered from the end of the anhepatic phase until 2 hours after reperfusion of the graft, and the effects on blood loss and red blood cell (RBC) transfusion requirements were compared. Transfusion policy was standardized in all patients. In addition, the biological effects of the two drugs, as assessed by coagulation and fibrinolytic markers obtained during surgery, were evaluated in a subgroup of patients from each treatment group and compared with an historical control group that did not receive antifibrinolytic drugs. There was no significant difference between the two groups in perioperative blood losses (AP, 6200 [4620-8735] mL; TA, 5945 [4495-8527] mL; median [range]) or in RBC transfusions requirements (AP, 9 [6.75-15.25] units; TA, 10 [6.5-13.5] units). Inhibition of fibrinolysis was observed with both drugs compared with the control group. Coagulation appeared to be activated more with AP, however, whereas fibrinolysis was inhibited more by TA. Blood losses and RBC transfusion requirements were comparable regardless of the drug administered. TA may be as valuable as AP for controlling fibrinolysis in LT.

Activated recombinant factor VII after cardiopulmonary bypass reduces allogeneic transfusion in complex non-coronary cardiac surgery: randomized double-blind placebo-controlled pilot study

Receiving an allogeneic transfusion may be an independent predictor of mortality for patients undergoing cardiac surgery. Furthermore, these patients utilize 15% of all donated blood in the UK. In our unit, 80% of patients undergoing complex non-coronary cardiac surgery requiring cardiopulmonary bypass (CPB) receive an allogeneic transfusion. Activated recombinant FVII (rFVIIa) may be effective in reducing this need for transfusion. Twenty patients undergoing complex cardiac surgery were randomized to receive rFVIIa or placebo after CPB and reversal of heparin. Two patients in the rFVIIa group received 13 units of allogeneic red cells and coagulation products compared with eight patients receiving 105 units of allogeneic red cells and coagulation products in the placebo group (relative risk of any transfusion 0.26; confidence interval 0.07-0.9; P=0.037). The groups did not differ for adverse events. Despite major limitations (underpowered study and prone to type I error), we have shown that rFVIIa significantly reduces the need for allogeneic transfusion in complex non-coronary cardiac surgery without causing adverse events.

Blood substitutes

Risk of disease transmission and limitations in the ability to transfuse in the prehospital or combat setting have stimulated research in the field of oxygen therapeutics. Several products have completed safety trials and are presently undergoing investigation for their efficacy. In the near future, the clinician will likely employ these products in the management of a variety of patient populations. Though similar in their oxygen carrying capacity, each agent possesses distinct physiologic effects. Understanding of the benefits and shortcomings of the various compounds is essential in order to optimally utilize them in various clinical settings. This review provides an overview of recent developments in the field of oxygen therapeutics and highlights results of clinical trials. Modified hemoglobin solutions of human or bovine origin and perfluorochemical-based emulsions are in advanced stages of clinical testing. Bovine hemoglobin-based solutions have been associated with vascular reactivity, methemoglobin formation and development of antibodies. Larger safety trials are necessary before they can find widespread use. Polymerized human hemoglobin solutions have a favorable safety profile in early trials and have been effective as a resuscitation fluid in circumstances when red cells may be unavailable. Unfortunately, outdated human blood, the substrate for this product, is itself in short supply. Perfluorocarbons similarly reduce the need for allogeneic transfusion, but the need for high-inspired oxygen levels currently limits use. Recombinant, polymer-encapsulated and additional forms of chemically modified hemoglobins are being developed and are undergoing testing in animal models Oxygen carriers offer a viable alternative to allogeneic transfusion. All oxygen therapeutic agents are not clinically equivalent. Optimal utilization requires a thorough understanding of the therapeutic potentials and adverse effects of the solution being considered for use.

Fat embolism and autologous blood transfusions in orthopaedic surgery

Fat embolism is a well-known complication associated with orthopaedic procedures like total hip or knee arthroplasty. The clinical relevance of fat embolism in association with orthopaedic procedures is, however, controversial. Although transesophageal echocardiography indicates echogenic material in the central circulation in more than 90% of patients undergoing cemented hip arthroplasty, the incidence of cardiac arrest due to pulmonary fat embolism is less than 1%. Cementation is known to increase the incidence of embolic complications. The duration of the pressure and the intensity of pressure inside the bone cavity are correlated with the incidence of fat emboli and the cardiopulmonary function. The use of modern cementing techniques and non-cemented arthroplasty reduces the incidence and the clinical risk of fat embolism. The disadvantages with allogeneic blood transfusions have encouraged the development of methods to reduce the need for such transfusions. Devices for salvage of blood during or after orthopaedic procedures have been shown to reduce the need for allogeneic transfusions. Shed blood may contain high concentrations of inflammatory mediators and may be contaminated with fat particles which may increase the risk of fat embolism. Transfusion of blood after washing and centrifugation and filtration of salvaged blood are available methods for transfusion of shed blood and that may reduce the amount of transfusion of fat.

Introduction of a Cell Salvage Service

SUMMARYIn the early 1990s it became apparent to a number of clinicians working at our institution that there was a need to develop a blood conservation program. At the time, the fear of viral transmission via blood transfusion had once more become a reality with the problems related to hepatitis C. This issue came close on the heels of the HIV epidemic, which had required enormous resource to minimize the risk of transfusion‐transmitted infection. The positive aspects of minimizing allogeneic transfusion and only resorting to this treatment when alternatives were not available seemed to be in keeping with the best ideals of preventative medicine. The formation of a hospital transfusion committee and the central use of cell salvage in the hospital's blood conservation policy has led to an atmosphere of awareness and improved knowledge about transfusion issues. The introduction of a cell salvage service has not only allowed better use of allogeneic supplies but in many cases prevented the need for allogeneic transfusion altogether. Other measures have led to improved transfusion practice but the presence in the main theater suite of a cell salvage service has acted as a catalyst to promote better blood transfusion within our institution.

Perflubron emulsion in prolonged hemorrhagic shock: influence on hepatocellular energy metabolism and oxygen-dependent gene expression.

Liver dysfunction as a result of impaired oxygen availability frequently occurs following hemorrhage and contributes to delayed mortality. Artificial oxygen carriers may improve oxygen supply to vital organs while avoiding the need for allogeneic transfusion. Rats were subjected to hemorrhagic hypotension (mean arterial pressure = 35-40 mmHg for 120 min) and were subsequently resuscitated with (1) stored whole rat blood, (2) pentastarch, or (3) pentastarch combined with perflubron emulsion (PFE; 2.7 or 5.4 g/kg body weight), a second-generation artificial oxygen carrier. Recovery of liver adenosine triphosphate, hepatocellular injury, and expression of glutamine synthetase 1, a gene that is induced by exposure of hepatocytes to low partial pressure of oxygen, were studied at 4 h of resuscitation. Stored whole blood or pentastarch failed to restore liver adenosine triphosphate concentrations after prolonged shock as compared to sham controls and resulted in increased gene expression of glutamine synthetase 1. Addition of 2.7 g PFE/kg restored liver adenosine triphosphate to control, whereas 5.4 g PFE/kg resulted in adenosine triphosphate concentrations significantly above control. Improved hepatocellular oxygen supply was also confirmed by restoration of the physiologic expression pattern of glutamine synthetase 1. Serum enzyme concentrations were highest after resuscitation with stored blood, whereas addition of PFE failed to further decrease enzyme concentrations as compared to pentastarch alone. Resuscitation with PFE is superior to stored blood or asanguineous resuscitation with respect to restoration of hepatocellular energy metabolism. The improved hepatocellular oxygen availability is reflected in normalization of oxygen-dependent gene expression. However, improved oxygen availability failed to affect early hepatocellular injury.

Efficacy of Acute Normovolemic Hemodilution in Cardiac Surgery

Policlinico di Monza, Italy. valter.casati@policlinicodimonza.itIn Reply:—I thank Van der Linden and De Hert for their comments regarding our article. 1I want to underline again that the aim of our work was not to demonstrate the efficacy per se of intraoperative acute normovolemic hemodilution (ANH) in adult open-heart surgery, but whether the introduction of low volume ANH in our standardized intraoperative blood-sparing protocol, constituted by the association of the infusion of tranexamic acid and the use of a cell-saving technique, could produce some additive advantage in terms of reduction of allogeneic transfusions. Furthermore, in the discussion of the article we justified our choice to perform low volume ANH with the intention to enroll also in the study patients with low body mass index and patients with relative low values of hemoglobin (12 g/dl).The negative results of our study clinically confirm the theoretical conclusions of mathematical analysis on ANH, 2which state that only high volume ANH in presence of significant intraoperative bleeding significantly reduces the need for allogeneic transfusions. 3,4Furthermore, our study may be considered an indirect demonstration of the efficacy of our intraoperative blood-sparing protocol to prevent excessive blood loss, rendering unnecessary the addition of low volume ANH in this type of patient.I totally agree with the conclusions of Van der Linden and De Hert: each blood conservation strategy must be studied considering the patient's limitations, the type of surgical procedures, and the health care environment. Because my opinion is that the addition of an adequate amount of ANH to our actual effective blood conservation approach 5may determine, particularly in patients with an increased risk for excessive bleeding, further improvements to our research of a cardiovascular surgery with the minimum number of patients necessitating donor blood; at the moment, various studies considering high volume ANH are in progress at our institution.

Pharmacologic preservation of the hemostatic system during cardiac surgery

Bleeding after cardiac surgery remains a major potential problem. Numerous pharmacologic approaches to attenuating hemostatic system activation in cardiac surgery patients have been studied to further improve patient management. Therapeutic approaches studied include inhibiting thrombin generation or activation, preserving platelet function, and decreasing the need for transfusion of allogeneic blood products. Pharmacologic approaches to reduce bleeding and transfusion requirements in cardiac surgery patients are based on either preventing or reversing the defects associated with the CPB-induced coagulopathy. The increasing use of platelet inhibitors (clopidogrel and IIb/IIIa receptor antagonists) and new anticoagulants (low–molecular weight heparins, pentasaccharide, recombinant hirudin, bivalirudin, and argatroban) also pose interesting problems in managing cardiac surgery patients. Aprotinin and lysine analogues (ϵ-aminocaproic acid and tranexamic acid) have become mainstay therapeutic agents to prevent bleeding and the potential need for allogeneic transfusion. Newer therapies that are important to consider include the potential of recombinant activated factor VIIa as a therapy for refractory bleeding after cardiac surgery.

Erythropoietin with Iron Supplementation To Prevent Allogeneic Blood Transfusion in Total Hip Joint Arthroplasty

The optimum regimen of epoetin alfa for prevention of allogeneic blood transfusion is unknown. To determine whether a modified regimen of epoetin alfa reduces allogeneic blood transfusion in patients undergoing hip arthroplasty. Randomized, double-blind, multicenter trial comparing two modified dose regimens of epoetin alfa with placebo. 13 teaching hospitals and 4 community hospitals in Canada. 201 patients undergoing primary hip arthroplasty who had a hemoglobin concentration of 98 to 137 g/L and did not predonate blood. Patients were assigned in a 3:5:5 ratio to receive four weekly doses of epoetin alfa, 40 000 U (high-dose; n = 44) or 20 000 U (low-dose; n = 79), or placebo (n = 78), starting 4 weeks before surgery. All patients received oral iron supplementation, 450 mg/d, for 42 or more days before surgery. The primary end point was allogeneic transfusion. Secondary end points were thromboembolic events and change in reticulocyte count and hemoglobin concentration. Both modified epoetin alfa regimens significantly reduced the need for allogeneic transfusion: Five (11.4%) patients in the high-dose group (P = 0.001) and 18 (22. 8%) patients in the low-dose group (P = 0.003) had transfusion, compared with 35 (44.9%) patients in the placebo group. The hematologic response was substantial in patients who received epoetin alfa. In the high-dose group, low-dose group, and placebo group, the preoperative increase in reticulocyte count was 58.8, 37. 0 and 1.8 x 10(9) cells/L (P < 0.001), respectively, and the increase in hemoglobin concentration was 19.5, 17.2, and 1.2 g/L (P < 0.001). The incidence of thromboembolic events did not differ among groups. Both modified epoetin alfa regimens were effective compared with placebo in reducing allogeneic transfusion in patients undergoing hip arthroplasty. Patients who received high-dose epoetin alfa had the lowest transfusion rate.

Tranexamic acid compared with high-dose aprotinin in primary elective heart operations: Effects on perioperative bleeding and allogeneic transfusions

Objective: Since excessive fibrinolysis during cardiac surgery is frequently associated with abnormal perioperative bleeding, many authors have advocated prophylactic use of antifibrinolytic drugs to prevent hemorrhagic disorders. We compared the effects of tranexamic acid (a synthetic antifibrinolytic drug) with aprotinin (a natural derivative product with antifibrinolytic properties) on perioperative bleeding and the need for allogeneic transfusions. Methods: In a single-center prospective randomized unblinded trial, 1040 consecutive patients undergoing primary, elective cardiac operations with cardiopulmonary bypass received either high-dose aprotinin or tranexamic acid. The aprotinin group (518 patients) received 280 mg in 20 minutes before the skin incision, 280 mg in the priming solution of the extracorporeal circuit, and a continuous infusion of 70 mg/h throughout the operation. The tranexamic acid group (522 patients) received 1 g in 20 minutes before the skin incision, 500 mg in the priming solution of the extracorporeal circuit, and a continuous infusion of 400 mg/h during the operation. Postoperative bleeding, perioperative transfusions, and hematologic variables were evaluated at fixed times. Postoperative thrombotic complications, intubation time, intensive care unit stay, and hospital stay were recorded. Results: Postoperative bleeding was similar in the 2 groups: aprotinin 250 mL (150-400 mL) versus tranexamic acid 300 mL (200-450 mL) (median and 25th-75th quartiles), median difference of 50 mL (95% confidence intervals, 0-50 mL). The number of transfusions and the outcome did not differ. Conclusions: Tranexamic acid and aprotinin show similar clinical effects on bleeding and allogeneic transfusion in patients undergoing primary elective heart operations. Since tranexamic acid is about 100 times cheaper than aprotinin, its use is preferable in this type of patient. (J Thorac Cardiovasc Surg 2000;120:520-7)

Transfusions in patients undergoing cardiac surgery with autologous blood.

Determinants of allogeneic blood use in cardiac surgery include preoperative factors such as female sex, age, body weight, hematocrit and red cell volume. We verified if these variables also predicted the need for allogeneic transfusions when autologous blood is predonated. Demographic and intraoperative variables, hemoglobin concentrations and transfusion requirements in patients undergoing cardiopulmonary bypass with autologous blood predonation were reviewed. Multivariate logistic regression and RECPAM tree-growing analyses were applied to identify the preoperative predictors of allogeneic transfusion in these patients. Data from 230 patients included in our autologous blood program between 1995 and 1998 were analysed. Patients undergoing complex/reoperative surgical procedures and patients over age 64yr with a low red cell volume (<2070ml) undergoing simple procedures were more likely to require allogeneic red cells. Younger patients with a low red cell volume undergoing simple procedures carried an intermediate risk. Allogeneic transfusion was avoided in 95% of patients undergoing simple procedures when red cell volume > or = 2070ml. In our institution, complex/reoperative surgery, low red cell volume and increased age are the main factors associated with the need for allogeneic red cell transfusion despite autologous blood predonation. Knowledge of the factors that limit the effectiveness of predonation with respect to allogeneic blood exposure should help clinicians decide which cardiac surgical patients should be included in autologous blood programs.

Radical retropubic prostatectomy: time trends, morbidity and mortality in Japan.

To assess the time trends, morbidity and mortality of contemporary anatomical radical retropubic prostatectomy (RRP) in a multi-institutional study in Japan, where RRP has become more popular in the last decade. Between January 1991 and August 1998, 638 patients underwent RRP at seven urological centres in Japan. Major complications (within 30 days of surgery) and the 30-day mortality were reviewed retrospectively. Of the patients, 12.9% were < 60 years old, 56.3% were 60-69 years old and 30.9% were >/= 70 years old (median age 67). Results The number of RRPs increased markedly, by more than sevenfold, from 1991-92 to 1996-97, mainly because there were more patients undergoing RRP in their sixth decade. The contribution of T1c disease increased in absolute and relative terms, from 13.9% in 1991-92 to 37.9% in 1997-98. Over time, the mean blood loss and the allogeneic transfusion rate decreased steadily. There was a trend toward more favourable outcomes for pathological variables (an increased percentage of organ-confined disease, decreased margin positivity and a decreased incidence of positive lymph node metastasis). The most common complications were wound-related (7.5%), or anastomotic leakage (4.1%). Major cardiopulmonary complications occurred in only two patients (0.31%, both pulmonary embolisms). One patient died from cerebral haemorrhage within 30 days of surgery, giving a mortality rate of 0.16%. s This study indicates a trend towards selecting patients most likely to benefit from RRP. Although the procedure is technically demanding, it can have an acceptably low rate of early complications, little mortality and need for allogeneic transfusion. The assessment of morbidity suggests a lower incidence of catastrophic thrombo-embolic and cardiac complications in Japanese patients than in Western men. The present data may be useful in decision-analysis models evaluating the role of therapy for Asian men with early-stage prostate cancer.

Usefulness of autologous blood transfusion for avoiding allogenic transfusion and infectious complications after esophageal cancer resection

Background: A retrospective investigation was conducted to determine whether autologous blood collection could reduce allogenic transfusion after resection of esophageal cancer and whether allogenic transfusion influenced postoperative infection. Methods: Patients (n = 100) who met the criteria for hemoglobin, age, body weight, and serum protein donated 800 mL of autologous blood from May 1994 to December 1997. The control group (n = 248) was selected from patients who met the same criteria and did not donate autologous blood over the 10 years before the start of autologous blood collection. Results: Only three patients (3%) from the autologous group required allogenic transfusion versus 84 patients (33.7%) from the control group. Sixteen of the 26 patients who received more than 4 units of allogenic blood contracted postoperative infections compared with 25 of 165 patients who did not (P <.0001). Autologous blood transfusion significantly increased the probability of avoiding allogenic transfusion (odds ratio, 27.58), and allogenic transfusion was significantly related to postoperative infection (odds ratio, 1.19), according to logistic regression analysis. Conclusions: Autologous blood collection reduces the need for allogenic transfusion in patients undergoing resection of esophageal cancer, and avoidance of allogenic transfusion may reduce the risk of postoperative infection.(Surgery 2000;127:185-92.)

How to Handle Erythropoietin in Orthopedic Surgery

SUMMARY Erythropoietin has been shown in numerous studies to be effective in raising the preoperative hematocrit and reducing the need for allogeneic transfusion in major orthopedic surgery1–4. Erythropoietin may be as good as or better than preoperative autologous5 donation. The safety profile seems well established. There are still a number of unresolved questions regarding its use. Many of these questions relate to the cost-effectiveness of this treatment. Erythropoietin is not appropriate for universal use; however, at times it may be the best or even the only treatment option available.

Comprehensive Multimodality Blood Conservation: 100 Consecutive CABG Operations Without Transfusion

Background. Despite the recent introduction of a number of technical and pharmacologic blood conservation measures, bleeding and allogeneic transfusion remain persistent problems in open heart surgical procedures. We hypothesized that a comprehensive multimodality blood conservation program applied algorithmically on the basis of bleeding and transfusion risk would provide a maximum, cost-effective, and safe reduction in postoperative bleeding and allogeneic blood transfusion. Methods. One hundred consecutive patients undergoing coronary artery bypass grafting were prospectively enrolled in a risk factor–based multimodality blood conservation program (MMD group). To evaluate the relative efficacy and safety of this comprehensive approach, comparison was made with a similar group of 90 patients undergoing coronary artery bypass grafting to whom the multimodality blood conservation program was not applied but in whom an identical set of transfusion guidelines was enforced (control group). To evaluate the cost effectiveness of the multimodality program, comparison was also made between patients in the MMD group and a consecutive series of contemporaneous, diagnostic-related group–matched patients. Results. One hundred consecutive patients in the MMD group underwent coronary artery bypass grafting without allogeneic transfusion. This compared favorably with the control population in whom a mean of 2.2 ± 6.7 units of allogeneic blood was transfused per patient (34 patients [38%] received transfusion). In addition, the volume of postoperative blood loss at 12 hours in the control group was almost double that of the MMD group (660 ± 270 mL versus 370 ± 180 mL [ p < 0.001]). Total costs for the MMD group in each of the three major diagnostic-related groups were equivalent to or significantly less than those in the consecutive series of diagnostic-related group–matched patients. Conclusions. Comprehensive risk factor–based application of multiple blood conservation measures in an optimized, integrated, and algorithmic manner can significantly decrease bleeding and need of allogeneic transfusion in coronary artery bypass grafting in a safe and cost-effective manner.

Effect of Recombinant Human Erythropoietin on Transfusion Risk in Coronary Bypass Patients

Background. Patients having a cardiac operation frequently require allogeneic blood transfusions despite surgical blood-conservation techniques. Recombinant human erythropoietin (Epoetin alfa) may augment this conservation by stimulating erythropoiesis. The safety and efficacy of perioperative use of Epoetin alfa to reduce the need of allogeneic transfusion was studied. Methods. A multicenter double-blind, placebo-controlled, parallel-group study involved 182 patients having coronary artery bypass grafting and randomized to receive Epoetin alfa (300 or 150 IU/kg) or placebo subcutaneously for 5 days before, on the day of, and for 2 days after operation. Results. Perioperative Epoetin alfa resulted in greater increases in baseline to preoperative hemoglobin levels and hematocrit (300 IU/kg) and in presurgery to postsurgical day 1 reticulocyte counts versus placebo ( p ≤ 0.05). However, there was no significant difference in transfusion requirements. Incidences of adverse events were similar in all study groups. Conclusions. Lower incidences of allogeneic blood exposure were observed in both Epoetin alfa–treated groups; however, the differences between all treatment groups were not significant. This was probably due to the relatively short 5-day preoperative course of Epoetin alfa therapy. There were no significant differences between the three groups relative to safety. Epoetin alfa was well tolerated in this population.

Reduction in Requirements for Allogeneic Blood Products: Pharmacologic Methods

Background. Numerous articles describe the reduction of perioperative bleeding by the therapeutic or prophylactic administration of drugs such as prostacyclin, desmopressin, and natural or synthetic antifibrinolytics. Methods. A review of the literature was carried out to help the reader define the indications of these drugs during cardiopulmonary bypass operations, highlight the questions that remain concerning their indications and modes of action, and suggest future studies to answer these remaining questions. Results. Prostacyclin reduces platelet trauma induced by extracorporeal circulation but does not effectively reduce postoperative bleeding and transfusion requirements. Desmospressin acts as a “glue,” improving platelet adhesion, and may be effective when postoperative bleeding is excessive, but its routine use in cardiac operations cannot be recommended. Natural and synthetic antifibrinolytics inhibit plasmin and plasmin-induced platelet dysfunction. These agents have been shown to decrease bleeding and the need for allogeneic transfusions after open heart operations. However, with antifibrinolytic drugs, the risk of thromboembolic phenomena cannot be neglected. With aprotinin, this risk appears to be minimal when the drug is used at concentrations high enough to inhibit plasma kallikrein also. Conclusions. Prophylactic antifibrinolytics are efficacious, but their routine use remains controversial, both for economic reasons and for fear of thromboembolic complications.

Perfluorocarbons are effective oxygen carriers in cardiopulmonary bypass.

Intravascular perfluorochemical (PFC) emulsions together with a high oxygen (O2) tension may increase the delivery of dissolved O2 to useful levels. A severely anemic model of cardiopulmonary bypass (CPB) was used to test the hypothesis that a novel PFC emulsion (PFCE; Oxygent [Alliance Pharmaceutical Corp., San Diego, CA] 90% w/v perflubron) used at a high PO2 during bypass delivers sufficient O2 to ameliorate hypoxic myocardial contractile dysfunction. Acutely anemic dogs (N = 42; hematocrit = 15.8 +/- 0.6% [mean +/- SEM] before CPB and 10.9 +/- 0.1% during CPB) were divided into four groups. Group 1 was a control (n = 12). As CPB was initiated, groups 2 (n = 10), 3 (n = 10), and 4 (n = 10) had 1.35 g PFC.kg-1, 2.7 g PFC.kg-1, or 5.4 g PFC.kg-1 added via the venous return cannula. Pre-CPB and post-CPB cardiac function was measured by the first derivative of left ventricular pressure (dP/dtmax). The dP/dtmax on separation from CPB was: group 1, 619 +/- 96; group 2, 738 +/- 56; group 3, 782 +/- 101; and group 4, 828 +/- 100 (p < 0.05 groups 3 and 4 versus group 1). Mortality during the first hour after separation from CPB was higher in group 1 than in PFCE treated dogs; however, this trend did not attain statistical significance (p < 0.065). The PFC dose was higher in survivors than in nonsurvivors (2.6 +/- 0.4 g PFC.kg-1 versus 1.2 +/- 0.5 g PFC.kg-1; p < 0.05). A PFCE used at a high PO2 provides sufficient physically dissolved O2 to relieve myocardial hypoxic injury in a severely anemic model of CPB. Current PFCEs are effective O2 carriers. This finding suggests that they can be used as a temporary erythrocyte substitute to diminish the need for allogeneic transfusions during cardiac operations.

Mathematical analysis of isovolemic hemodilution indicates that it can decrease the need for allogeneic blood transfusion.

The implementation of acute isovolemic hemodilution prior to surgical blood loss is a strategy used in an attempt to diminish the need for or obviate allogeneic transfusion and to avert the potential, attendant complications. Studies examining the efficacy of this technique have produced conflicting results. The present mathematical analysis was undertaken to resolve these conflicts by determining the efficacy of hemodilution and examining the influence of the variables affecting the outcome. Efficacy was defined as the volume of additional blood loss permitted and the volume and number of units of allogeneic blood saved from transfusion. A mathematical analysis evaluated the impact of circulating blood volume and initial and target hematocrits on the efficacy of isovolemic hemodilution. It was assumed that 1) hemodilution was completed before surgical blood loss; 2) transfusion of removed blood was begun when the target hematocrit was reached and lost surgical blood was replaced at a rate that maintained the target hematocrit; 3) allogeneic transfusion was begun after all autologous blood drawn was transfused; 4) normovolemia was maintained; and 5) a unit of allogeneic blood contains 175 mL of red cells. The analysis showed that isovolemic hemodilution can result in substantial additional allowable surgical blood loss that can diminish the need for or obviate allogeneic transfusion of red cells. Larger circulating blood volume, higher initial hematocrits, and lower target hematocrits increase the efficacy of hemodilution. Removal and isovolemic replacement of 1 to 2 units of blood provide minimal potential savings, as does hemodilution to a circulating (target) hematocrit of 30 percent. The extension of hemodilution to a hematocrit of (or below) 20 percent allows a disproportionately greater surgical blood loss and diminishes the need for allogeneic transfusion. It allows, for example, an additional 4.5 L of surgical blood loss, which represents a savings of 4 units of allogeneic blood when a patient with an initial blood volume of 5.0 L and a hematocrit of 45 percent undergoes isovolemic hemodilution to a hematocrit of 15 percent. Isovolemic hemodilution can diminish or in some circumstances eliminate the need for allogeneic transfusion.

Perioperative Interventions to Decrease Transfusion of Allogeneic Blood Products

To discuss some of the many options available for decreasing perioperative transfusion of allogeneic blood products. We review the issues that focus on the goal of developing an appropriate transfusion strategy in consideration of the individual patient's preexisting conditions, physiologic requirements, perioperative stress, and coagulation status. Increased awareness of transfusion-related morbidity from allogeneic blood products has resulted in increased development and application of alternatives to allogeneic transfusion. Preoperative donation and perioperative collection of autologous blood and blood products decrease exposure to allogeneic blood. Pharmacologic agents, such as antifibrinolytics, may also decrease the need for allogeneic transfusion. Perioperative use of laboratory tests of coagulation function facilitates the rapid and specific diagnosis of coagulation disorders. Physicians now have considerable appreciation of the risks and benefits of blood product transfusion. This knowledge has resulted in conservative and scientific approaches to therapy for perioperative bleeding and coagulopathy.