Predictors of transfusion requirements for cardiac surgical procedures at a blood conservation center

BACKGROUND: Previous studies defining perioperative risk factors for allogeneic transfusion requirements in cardiac surgery were limited to highly selected cardiac surgery populations or were associated with high transfusion rates. The purpose of this study was to determine perioperative risk factors and create a formula to predict transfusion requirements for major cardiac surgical procedures in a center that practices a multimodality approach to blood conservation. METHODS: We performed an observational study on 307 consecutive patients undergoing coronary artery bypass grafting, valve, and combined (coronary artery bypass grafting and valve) procedures. An equation was derived to estimate the risk of transfusion based on preoperative risk factors using multivariate analysis. In patients with a calculated probability of transfusion of at least 5%, intraoperative predictors of transfusion were identified by multivariate analysis. RESULTS: Thirty-five patients (11%) required intraoperative or postoperative allogeneic transfusions. Preoperative factors as independent predictors for transfusions included red blood cell mass, type of operation, urgency of operation, number of diseased vessels, serum creatinine of at least 1.3 mg/dL, and preoperative prothrombin time. Intraoperative factors included cardiopulmonary bypass time, three or fewer bypass grafts, lesser volume of acute normovolemic hemodilution removed, and total crystalloid infusion of at least 2,500 mL. The derived formula was applied to a validation cohort of 246 patients, and the observed transfusion rates conformed well to the predicted risks. CONCLUSIONS: A multimodality approach to blood conservation in cardiac surgery resulted in a low transfusion rate. Identifying patients' risks for transfusion should alter patient management perioperatively to decrease their transfusion rate and make more efficient use of blood resources.     

Blood conservation in cardiac surgery. Preliminary results with an institutional commitment.

To evaluate the effect of blood conservation in cardiac surgery, use of blood products was analyzed in patients undergoing CABG before and after implementation of blood conservation techniques. Age, sex, coronary anatomy, ejection fraction, cardiopulmonary bypass time, and the preoperative hematocrit, platelet count, and clotting studies were similar in both groups. Methods of blood conservation included autologous transfusion of blood withdrawn before bypass, autotransfusion of shed mediastinal blood, strict protocols for transfusion, and acceptance of normovolemic anemia. With blood conservation, 25.5% of patients received no transfusions and 54.9% received blood only. Significant reductions (p less than 0.001) were achieved in the transfusion of blood from 6.8 +/- 2.4 to 2.3 +/- 2.6 units per patient and of plasma from 2.5 +/- 2.2 to 0.6 +/- 2.0 units per patient. Reductions in the use of platelets and cryoprecipitate were substantial, although not significant. Total donor exposure was reduced significantly from 13.1 +/- 7.3 to 4.3 +/- 6.7 donors per patient. The postoperative hematocrit was significantly lower and remained so at discharge. However, 30 days later there was no difference. This reduction in transfusion requirements decreased costs and donor exposure.     

Bloodless cardiac surgery is associated with decreased morbidity and mortality

BACKGROUND: Blood transfusion with cardiac surgery accounts for 20% of transfusions in the United States. The effect of perioperative transfusion on cardiac surgery outcomes is unknown. We hypothesized that cardiac surgery with perioperative blood transfusion was associated with worse outcomes. METHODS: A prospectively maintained (Society of Thoracic Surgeons) institutional database was analyzed from 2000 to 2005. All patients undergoing coronary artery bypass and/or valve operations were evaluated for the association of preoperative and intraoperative risk factors with blood transfusion. The association of transfusion with postoperative complications and mortality was evaluated. RESULTS: During the study period, 2691 patients met inclusion criteria. Sixty-four percent received transfusions. Preoperative risk factors associated with transfusion (p < 0.05) were lung disease, elevated creatinine, peripheral vascular disease, and previous cardiac interventions. Patients requiring transfusion were older (mean 65.2 vs. 61.2 years, p < 0.001). Transfusion was associated with longer cross-clamp (median 78 vs. 88 minutes, p < 0.001) and perfusion times (median 114 vs. 128 minutes, p < 0.001). Perioperative blood transfusion was associated with increased postoperative complications (53.5% vs. 30.5%, p < 0.001). Significant transfusion-associated complications were renal failure, prolonged ventilation time, pneumonia, cardiac arrest, gastrointestinal complications, atrial fibrillation, stroke, myocardial infarction, and bleeding requiring reoperation. Blood transfusion was associated with an increased operative mortality (3.4% vs. 1.7%, p = 0.005) and length of stay after surgery (median 6 vs. 5 days p < 0.001). CONCLUSION: Identification and management of risk factors associated with transfusion may reduce the transfusion requirement, minimize perioperative complications and improve outcomes. Bloodless cardiac surgery is associated with a decreased morbidity and mortality.     

Programmatic blood conservation in cardiac surgery

Despite efforts to reduce blood transfusion rates in cardiac surgery over the past 40 years, cardiac surgery still consumes 10% to 20% of the blood transfused in the United States. This large demand has not only placed a significant pressure on the national blood supply, resulting in frequent shortages, but also has lead to many technical and pharmacological advances in blood conservation strategies in recent years. Recently, studies have shown that an organized approach to blood conservation in cardiac surgery is effective in significantly reducing the perioperative use of allogeneic blood and blood products. However, blood conservation techniques are multiple, varied, and in many situations costly and thus cannot be uniformly applied to all patients. Early preoperative planning and a coordinated perioperative plan allow the appropriate use of blood conservation modalities to ensure that their benefits span the entire perioperative period. This article describes some of the modalities currently used in patients undergoing cardiac surgery.     

Polymerized bovine hemoglobin solution as a replacement for allogeneic red blood cell transfusion after cardiac surgery: results of a randomized,double-blind trial

BACKGROUND: Blood loss leading to reduced oxygen-carrying capacity is usually treated with red blood cell transfusions. This study examined the hypothesis that a hemoglobin-based oxygen-carrying solution can serve as an initial alternative to red blood cell transfusion. METHODS: In a randomized, double-blind efficacy trial of HBOC-201, a total of 98 patients undergoing cardiac surgery and requiring transfusion were randomly assigned to receive either red blood cell units or HBOC-201 (Hemopure; Biopure Corporation, Cambridge, Mass) for the first three postoperative transfusions. Patients were monitored before and after transfusion, at discharge, and at 3 to 4 weeks after the operation for subsequent red blood cell use, hemodynamics, and clinical laboratory parameters. RESULTS: The use of HBOC-201 eliminated the need for red blood cell transfusions in 34% of cases (95% confidence interval 21%-49%). Patients in the HBOC group received a mean of 1.72 subsequent units of red blood cells; those who received red blood cells only received a mean of 2.19 subsequent units (P =.05). Hematocrit values were transiently lower in the HBOC group but were similar in the two groups at discharge and follow-up. Oxygen extraction was greater in the HBOC group (P =.05). Mean increases in blood pressure were greater in the HBOC group, but not significantly so. CONCLUSION: HBOC-201 may be an initial alternative to red blood cell transfusions for patients with moderate anemia after cardiac surgery. In a third of cases, HBOC-201 eliminated the need for red blood cell transfusion, although substantial doses were needed to produce this modest degree of blood conservation.     

Mechanisms and attenuation of hemostatic activation during extracorporeal circulation.

Patients undergoing cardiac surgery with cardiopulmonary bypass are at risk for excessive microvascular bleeding, which often leads to transfusion of allogeneic blood and blood components as well as reexploration in a smaller subset of patients. Excessive bleeding after cardiac surgery is generally related to a combination of several alterations in the hemostatic system pertaining to hemodilution, excessive activation of the hemostatic system, and potentially the use of newer, longer-acting antiplatelet or antithrombotic agents. Although several nonpharmacologic strategies have been proposed, this review summarizes the role of pharmacologic interventions as means to attenuate the alterations in the hemostatic system during CPB in an attempt to reduce excessive bleeding, transfusion, and reexploration. Specifically, agents that inhibit platelets, fibrinolysis, factor Xa and thrombin, as well as broad-spectrum agents, have been investigated with respect to their role in reducing consumption of clotting factors and better preservation of platelet function. Prophylactic administration of agents with antifibrinolytic, anticoagulant, and possibly antiinflammatory properties can decrease blood loss and transfusion. Although aprotinin seems to be the most effective blood conservation agent (which is most likely related to its broad-spectrum nature), agents with isolated antifibrinolytic properties may be as effective in low-risk patients. The ability to reduce blood product transfusions and to decrease operative times and reexploration rates favorably affects patient outcomes, availability of blood products, and overall health care costs.     

Clinical outcomes in cardiac surgery: conventional surgery versus bloodless surgery

Bleeding during and after cardiac operations and the effects of cardiopulmonary bypass hemodilution commonly result in blood transfusions. Excessive microvascular bleeding can result in re-exploration and prolonged hospitalization. Nearly 20% of all blood transfusions in the United States are associated with cardiac surgery. The risks associated with the use of allogeneic blood product transfusion include mistransfusion, immunologic complications, and transmission of infectious diseases. The large demand for blood products places significant pressure on the national blood supply, resulting in frequent shortages. The variability in transfusion practice of cardiac surgery patients suggests that sound blood management and a conservative approach to this population can result in reduced transfusions without increasing morbidity or mortality and avoiding complications associated with allogeneic blood transfusion.     

The use of autologous blood in patients undergoing subcutaneous mastectomy or reduction mammaplasty

Adverse reactions are reported following 2% of transfusions. Posttransfusion viral hepatitis may occur in 8% of patients receiving homologous blood. Plastic surgery procedures, such as reduction mammaplasty and subcutaneous mastectomy, are associated with moderate blood loss that may require transfusion. Over a five-year period we offered autologous blood transfusions to 88 patients scheduled for such surgery. Approximately ten days before their operation, 72 patients each donated 450 ml of blood, which was then available for transfusion during surgery. When admitted for surgery, the patients' mean reduction in hemoglobin was 6.9%. Their average calculated blood loss was 930 ml, with a net loss of 483 ml after receiving their own blood. No complications occurred. Only 2 of these patients required an additional unit of homologous blood. Six of the 16 patients who did not donate blood preoperatively required homologous blood transfusions. The use of safe autologous blood was enthusiastically accepted by the surgical and anesthesia staff, blood bank personnel, and the patients.     

Management of intraoperative fluid balance and blood conservation techniques in adult cardiac surgery

Blood transfusions are associated with adverse physiologic effects and increased cost, and therefore reduction of blood product use during surgery is a desirable goal for all patients. Cardiac surgery is a major consumer of donor blood products, especially when cardiopulmonary bypass (CPB) is used, because hematocrit drops precipitously during CPB due to blood loss and blood cell dilution. Advanced age, low preoperative red blood cell volume (preoperative anemia or small body size), preoperative antiplatelet or antithrombotic drugs, complex or re-operative procedures or emergency operations, and patient comorbidities were identified as important transfusion risk indicators in a report recently published by the Society of Cardiovascular Anesthesiologists. This report also identified several pre- and intraoperative interventions that may help reduce blood transfusions, including off-pump procedures, preoperative autologous blood donation, normovolemic hemodilution, and routine cell saver use.A multimodal approach to blood conservation, with high-risk patients receiving all available interventions, may help preserve vital organ perfusion and reduce blood product utilization. In addition, because positive intravenous fluid balance is a significant factor affecting hemodilution during cardiac surgery, especially when CPB is used, strategies aimed at limiting intraoperative fluid balance positiveness may also lead to reduced blood product utilization.This review discusses currently available techniques that can be used intraoperatively in an attempt to avoid or minimize fluid balance positiveness, to preserve the patient's own red blood cells, and to decrease blood product utilization during cardiac surgery.     

Transfusions in patients undergoing cardiac surgery with autologous blood

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.     

Variability in Transfusion Practice for Coronary Artery Bypass Surgery Persists Despite National Consensus Guidelines: A 24-Institution Study

Background: An estimated 20% of allogeneic blood transfusions in the United States are associated with cardiac surgery. National consensus guidelines for allogeneic transfusion associated with coronary artery bypass graft (CABG) surgery have existed since the mid- to late 1980s. The appropriateness and uniformity of institutional transfusion practice was questioned in 1991. An assessment of current transfusion practice patterns was warranted.

Methods: The Multicenter Study of Perioperative Ischemia database consists of comprehensive information on the course of surgery in 2,417 randomly selected patients undergoing CABG surgery at 24 institutions. A subset of 713 patients expected to be at low risk for transfusion was examined. Allogeneic transfusion was evaluated across institutions. Institution as an independent risk factor for allogeneic transfusion was determined in a multivariable model.

Results: Significant variability in institutional transfusion practice was observed for allogeneic packed red blood cells (PRBCs) (27-92% of patients transfused) and hemostatic blood components (platelets, 0-36%; fresh frozen plasma, 0-36%; cryoprecipitate, 0-17% of patients transfused). For patients at institutions with liberal rather than conservative transfusion practice, the odds ratio for transfusion of PRBCs was 6.5 (95% confidence interval [CI], 3.8-10.8) and for hemostatic blood components it was 2 (95% CI, 1.2-3.4). Institution was an independent determinant of transfusion risk associated with CABG surgery.     

Blutungsprobleme in der offenen Herzchirurgie

Across centers, transfusion can vary eightfold for the same mediastinal drainage after adult cardiac operations. Excessive blood drainage resulting in increased transfusions occurs in 29% of patients. Various strategies have been proposed to decrease bleeding and allogenic transfusion requirements in the perioperative period of heart surgery. Blood conservation methods were reviewed critically. Avoidance of preoperative anemia, tolerance of low hemoglobin concentrations, the use of autologous blood, and adherence to a strict transfusion protocol will reduce the use of allogenic transfusions. Perioperatively, maintenance of normothermia contributes to improved hemostasis.     

Optimizing transfusion in vascular surgery: is bloodless surgery an option?

The prospect of surgery without blood loss is an emerging reality. Use of a blood conservation strategy is gaining increasing recognition as a sound and practical approach, especially for the majority of large blood loss surgeries. However, critical situations still occur in which transfusions are necessary or unavoidable for the short-term survival of the patient. The decision-making processes for determining when to transfuse, which blood products to give, and how much are presented here with an evaluation of the risks of transfusion and a discussion on blood conservation strategies. Modalities that may be used in such strategies include restricted phlebotomy, the implementation of restrictive transfusion triggers, acute normovolemic hemodilution, intraoperative and postoperative blood salvage, and refined operative techniques to achieve meticulous hemostasis. In addition, the proper use of erythropoiesis-stimulating agents well before surgery can reduce the number of units transfused. The risks and costs of allogeneic blood transfusions underscore the need for and value of blood conservation techniques. Increasingly, hospitals are adopting blood conservation strategies as part of their routine practice. Blood conservation is a rapidly evolving field in which active research is expanding our understanding of the molecular, physiologic, and clinical aspects of hematopoiesis, circulatory response, coagulation enigmas, artificial oxygen carriers, and the impact of anemia on organ function. Ongoing research offers the possibility of replacement or elimination of allogeneic blood transfusions in a variety of clinical settings.     

Does the Use of Erythropoietin Reduce the Risk of Exposure to Allogeneic Blood Transfusion in Cardiac Surgery? A Systematic Review and Meta‐Analysis

BACKGROUND: The use of blood conservation techniques is important in cardiac surgery as postoperative bleeding is common and allogeneic blood transfusion carries the risk of transfusion reactions and infection transmission. Erythropoietin with and without preoperative autologous blood donation is one of the modalities to avoid allogeneic blood transfusion. The objective of this review was to assess the effectiveness of erythropoietin in reducing the risk of exposure to allogeneic blood transfusion during or after cardiac surgery. METHODS: A meta-analysis of 11 identified randomized controlled trials, reporting comparisons between erythropoietin and control, was undertaken. The primary outcome was the number of patients exposed to allogeneic blood transfusion during or after cardiac surgery. RESULTS: Eleven studies, involving 708 patients, met the inclusion criteria for this review. In total, 471 patients were given erythropoietin, and 237 patients formed the control group. The administration of erythropoietin with and without preoperative autologous blood transfusion prior to cardiac surgery is associated with a significant risk reduction: RR = 0.28 (95% CI 0.18-0.44, P < 0.001) and RR = 0.53 (95% CI 0.32-0.88, P < 0.01), respectively. CONCLUSION: The administration of erythropoietin before cardiac surgery is associated with a significant reduction in the risk of exposure to allogeneic blood transfusion. Further studies are warranted to define the patients' subgroups that may benefit the most from EPO administration.     

Blood conservation in cardiac surgery: let's get restrictive

Despite increasing evidence suggesting harmful effects of blood transfusions, physician practices are slow to change. A systematic approach is required to successfully minimize the need for red cell transfusions in the perioperative cardiac surgical patient. This involves preoperative, intraoperative, and postoperative strategies to minimize blood loss and maximize blood conservation. In addition it requires physician education regarding the potential deleterious effects of blood and the more recent evidence that restrictive transfusion strategies are safe and possibly beneficial to postoperative surgical outcomes. In this article, we review the data with respect to blood transfusions in cardiac surgery patients as well as management strategies to minimize the need for blood transfusions in the perioperative period.     

An audit of transfusion of red blood cell units in pediatric anesthesia

Background:  Patients undergoing surgery are an important user of red blood cells (RBC). Increasingly, medical staff and patients wish to know the likelihood of RBC transfusion for appropriate resource allocation and to inform preoperative discussions regarding risk. Although some adult data are available, little is known about RBC use in children.
Aim:  The aim of this study was to describe RBC use in the perioperative period in a large pediatric hospital.
Methods:  Over a 2-year period the hospital operating theatre database and trauma registry was merged with the blood bank database to identify episodes where RBC units were transfused in association with anesthesia. Incidence of transfusion of RBC units associated with particular procedures was then calculated.
Results:  A total of 21 441 patients underwent 32 511 anesthetics from January 1, 2006 to December 31, 2007, and 9838 units of RBC were released from the hospital blood bank of which 4070 (41%) were transfused in the perioperative period. Cardiac surgery was the greatest user of RBC units (2359 units). Acute major trauma accounted for only 159 units. Overall 6.3% of anesthetics were associated with a RBC transfusion. The procedures with the greatest frequency of RBC transfusion were cardiac surgery on bypass (79%), cardiac off bypass (55%), liver transplant (87%) and cranioplasty (61%).
Conclusion:  In a tertiary pediatric hospital surgery accounts for a substantial proportion of total RBC use, with particular procedures accounting for the majority of transfusions.     

Utilization and efficacy of autologous blood predeposit in radical prostatectomy with lymphadenectomy: implications for blood conservation and physician education programs.

Autologous blood predeposit is a widely used transfusion practice that has become a standard of care for elective surgery. Despite the support for this practice there are unanswered questions in the usage and efficacy of autologous blood programs. This study is a prospective analysis of 52 consecutively audited urologic patients undergoing elective, radical prostatectomy with lymphadenectomy in which all 52 patients predonated autologous blood. Preoperative blood donation, blood transfused, surgical blood lost, and the "transfusion trigger" were evaluated for each of these patients. We conclude (1) the rate of homologous blood exposure (15%) despite preoperative autologous blood donation in every patient indicates a need for innovative blood conservation strategies to minimize homologous blood transfusion in this surgical group. (2) Unnecessary autologous transfusions could be identified in 8 (15%) of 52 patients, all of which were single unit autologous blood transfusions. (3) Physician education programs that emphasize increased procurement of autologous blood along with more conservative transfusion of this blood are needed to avoid necessary homologous blood and unnecessary autologous blood transfusion.     

Effect of autologous blood donation in patients undergoing elective spine surgery.

Autologous blood predeposit before elective surgery is a rapidly expanding transfusion practice. A 3-year analysis of an autologous blood predeposit program was conducted to assess its impact on orthopaedic spine surgery. It was concluded that, first, autologous blood donation has resulted in a reduction of homologous blood transfusions in patients undergoing elective spine procedures from 26% to 13% (P = .02). Second, autologous blood preoperative donation in elective spine surgery has increased significantly, so that autologous blood as an alternative to homologous blood transfusion now represents a standard of practice for elective spine surgery at the institution included in the study. Third, limitations of preoperative autologous blood procurement suggest that application of additional blood conservation interventions as alternatives to homologous blood would be important contributors to achieving "bloodless" surgery in this setting.     

Autologous blood donation in cardiac surgery: reduction of allogeneic blood transfusion and cost-effectiveness

OBJECTIVE: The purpose of this study was to assess transfusion requirements in patients undergoing cardiac surgery with and without autologous blood donation and to calculate the costs of predonation from the hospital perspective. DESIGN: Observational study. SETTING: Single university hospital. PARTICIPANTS: Four thousand three hundred twenty-five patients undergoing elective cardiac surgery with and without autologous blood donation. INTERVENTIONS: Eight hundred forty-nine patients (20%) underwent autologous blood donation, whereas 3,476 (80%) did not. Perioperative allogeneic blood transfusion was recorded as the primary endpoint. To avoid selection bias, patients were stratified according to their preoperative risk score. A decision model was derived from acquired data for the optimization of autologous blood donation. MEASUREMENTS AND MAIN RESULTS: Allogeneic blood transfusion rate was 13% in patients with predonation versus 48% without predonation (p < 0.05). This difference remained statistically significant even after risk stratification. The predonation of 1, 2, or 3 units reduced the probability of receiving allogeneic blood to 24%, 14%, and 9%, respectively. An efficient program of predonation within the department of anesthesiology allowed keeping the costs of predonation low. Decision-tree analysis revealed that predonation of 2 autologous units of blood saved the most allogeneic blood for the smallest increase in costs. Incremental cost for male patients predonating 2 units was dollars 33 (US), whereas for females predonation could be done at no extra cost in comparison to patients without predonation. CONCLUSION: Autologous blood donation significantly reduces allogeneic blood requirement in cardiac surgery. If adjusted for diagnosis and gender, autologous blood donation is a cost-effective alternative to reduce allogeneic blood consumption.     

An evidence-based approach to red blood cell transfusions in asymptomatically anaemic patients

Introduction

Surgeons and physicians encounter blood transfusions on a daily basis but a robust evidence-based strategy on indications and timing of transfusion in asymptomatic anaemic patients is yet to be determined. For judicious use of blood products, the risks inherent to packed red blood cells, the patient’s co-morbidities and haemoglobin (Hb)/haematocrit levels should be considered. This review critiques and summarises the latest available evidence on the indications for transfusions in healthy and cardiac disease patients as well as the timing of transfusions relative to surgery.

Methods

An electronic literature search of the MEDLINE^®, Google Scholar™ and Trip databases was conducted for articles published in English between January 2006 and January 2015. Studies discussing timing and indications of transfusion in medical and surgical patients were retrieved. Bibliographies of studies were checked for other pertinent articles that were missed by the initial search.

Findings

Six level 1 studies (randomised controlled trials or systematic reviews) and six professional society guidelines were included in this review. In healthy patients without cardiac disease, a restrictive transfusion trigger of Hb 70–80g/l is safe and appropriate whereas in cardiac patients, the trigger is Hb 80–100g/l. The literature on timing of transfusions relative to surgery is limited. For the studies available, preoperative transfusions were associated with a decreased incidence of subsequent transfusions and timing of transfusions did not affect the rates of colorectal cancer recurrence.