Drugs to Minimize Perioperative Blood Loss in Cardiac Surgery

Pharmacological approaches to reducing allogeneic blood exposure

This article discusses evidence for the role of pharmacological interventions such as the protease inhibitor aprotinin (Trasylol), lysine analogue anti-fibrinolytics [tranexamic acid (Cyclokapron) and epsilon aminocaproic acid (Amicar)], DDAVP (Desmopressin) and recombinant Factor VIIa (NovoSeven), in preventing the need for blood and blood-component therapies after major (cardiac, hepatic and orthopaedic/trauma) surgery. The data show that aprotinin is consistently effective in reducing globally the transfusion burden in cardiac and hepatic surgical procedures. However, there are little data to support its use in routine elective orthopaedic surgery. Multiple studies have failed to show an increased risk for myocardial ischaemia or infarction with aprotinin, and there may even be a reduced incidence of perioperative stroke in patients undergoing cardiac surgery. An increased probability of a hypersensitivity reaction when the drug is readministered within a 6-month period remains a significant issue. The data for the lysine analogue anti-fibrinolytics show no evidence of efficacy in reducing the transfusion burden for epsilon aminocaproic acid and inconsistent results with tranexamic acid in cardiac and hepatic surgery. As with aprotinin therapy, there is a paucity of data to support their use in routine elective orthopaedic surgery. There are no data to support the routine use of DDAVP to reduce the transfusion burden. Limited data suggest that this drug may be effective when a defect in platelet function is demonstrated. This aspect deserves further investigation. Recombinant activated Factor VII (rFVIIa) has proven benefit for its licensed indication to reduce bleeding in haemophiliacs with inhibitors to Factors VIII and IX. Reports of benefit in other instances are largely anecdotal. Hence, at this time it is therefore speculative and premature to suggest whether there is a place for this agent in routine clinical practice. No adequately powered, placebo-controlled prospective studies are available to investigate the safety of the lysine analogues, DDAVP or rFVIIa in cardiac, hepatic or orthopaedic surgery.

A model of the direct and indirect effects of aprotinin administration on the overall costs of coronary revascularization surgery in a university teaching hospital cardiothoracic unit

BACKGROUND

Cardiac patients sometimes bleed postoperatively and consequently require rethoracotomy, necessitating a longer stay in the intensive care unit (ICU) of the cardiothoracic unit (CTU). When ICU capacity is limited, rethoracotomy necessitates postponing treatment of the next patient. Aprotinin, a bovine lung-derived proteinase inhibitor, has been shown to reduce the frequency of rethoracotomies in cardiac patients.

OBJECTIVE

This study was undertaken to quantify the reduction of potentially avoidable cost to the CTU of postoperative bleeding, both directly and indirectly, by administering aprotinin before and during coronary artery bypass graft (CABG).

METHODS

A novel, validated operational research model was developed, featuring the principal CABG-related health care resource parameters believed to influence waiting lists and times. Factors and costs were derived from both local data from a CTU and relevant recent literature.

RESULTS

According to the model, aprotinin therapy reduced the waiting list by approximately 3% by reducing the number of rethoracotomies. Using data from the literature, for an annual throughput of 431 patients who would receive aprotinin costing 97,333 pounds per year, the annual net savings to the CTU would be 46,586 pounds, which comprised direct savings on blood products of 35,036 pounds and indirect marginal savings of 11,550 pounds derived from 3.2% fewer rethoracotomies (each at a marginal cost of 837 pounds). By reason, then, reinvesting savings in increasing CTU capacity would yield further waiting-list reductions and improve patient morbidity. These results had 2 major limitations. First, it was assumed that all operations would have the same duration and all surgeons would perform operations in the same manner. Second, nonurgent patients were assumed to have been treated in order of strict referral sequence, which may not be done in real-world practice.

CONCLUSIONS

Aprotinin reduced costs in CABG directly by reducing the use of blood products and indirectly by reducing waiting lists, as well as by reducing morbidity and mortality associated with waiting time.

Safety and efficacy of methods for reducing perioperative allogeneic transfusion: a critical review of the literature

A number of pharmacologic and nonpharmacologic technologies are in current use to minimize perioperative homologous blood use. Clinical trials, many of them randomized controlled trials, have been done evaluating these approaches and have demonstrated their efficacy. However, data on safety has relied mostly on case reports, uncontrolled studies, and, for the pharmacologic agents, extrapolation from the nonsurgical setting. In this review I analyze the data from the randomized trials and the lower-level evidence studies to provide the best estimates in safety with these alternatives. In general, these alternatives are safe with proper dosing and monitoring of effects. With aprotinin, the primary concern is anaphylaxis, and this predominantly with re-exposure. With aprotinin and with the anti-fibrinolytics, increased venous thromboembolic risk has not been a consistent finding. Tranexamic acid use intraoperatively is advantageous, but postoperative use appears to have no advantage and may be associated with renal dysfunction. DDAVP is low-risk, provided it is not overused, which can induce hyponatremia. Autologous predonation probably has similar risks as homologous blood with respect to transfusion errors and bacterial infection. As with most medical interventions, we must be vigilant to prevent human error.

Massive blood transfusion in the elective surgical setting

Massive haemorrhage in elective surgery can be either anticipated (e.g. organ transplantation) or unexpected. Management requires early recognition, securing haemostasis and maintenance of normovolaemia. Transfusion management involves the transfusion of packed red cells, platelet concentrates and plasma (fresh frozen plasma and cryoprecipitate). Blood product support should be based on clinical judgment and be guided by repeated laboratory tests of coagulation. Although coagulation tests may not provide a true representation of in vivo haemostasis, they do assist in management of haemostatic factors. Below critical levels (prothrombin time or activated partial thromboplastin time >1.8; fibrinogen <1.0 g/l; platelet count < 80 x 10(9) 1(-1)) it is difficult to achieve haemostasis. Despite seemingly adequate blood component therapy there remain situations where haemorrhage is uncontrollable. In this setting, alternative approaches must be considered. These include the use of other blood products (e.g. prothrombin complex concentrates; fresh whole blood; fibrin glue) and pharmacological agents (e.g. aprotinin). Complications of massive transfusion result in significant morbidity and mortality. These may be secondary to the storage lesion of the transfused blood products, disseminated intravascular coagulation, hypothermia or hypovolaemic shock. The use of fresh blood products and leucocyte-reduced packed red cells and platelets, may minimise some of the adverse clinical sequelae.

Is the kaolin or celite activated clotting time affected by tranexamic acid?

BACKGROUND

During cardiopulmonary bypass, the activated clotting time is frequently used for determination of anticoagulation, and either Celite or kaolin are used as activators. If aprotinin is administered concomitantly, the Celite activated clotting time (C-ACT) becomes significantly higher than the kaolin activated clotting time (K-ACT). Therefore, insufficient anticoagulation using C-ACT in the presence of aprotinin is a major concern. Whether the application of tranexamic acid (TA), a pharmacologic alternative to aprotinin, has similar effects has not been studied before.

METHODS

An in vitro study using the blood of healthy volunteers was performed. Both C-ACT and K-ACT were measured at baseline, after adding TA, and after adding TA and heparin. In addition, 30 patients undergoing primary cardiac operations had simultaneous measurements of C-ACT and K-ACT after skin-incision, 5 minutes after the application of heparin and TA, every 30 minutes during cardiopulmonary bypass, and 10 minutes after the application of protamine.

RESULTS

In vitro, C-ACT and K-ACT correlated significantly at each measurement. Tranexamic acid had no influence on the activated clotting time. In vivo, C-ACT and K-ACT did not differ significantly, but at each time C-ACT tended to be greater than K-ACT (p = 0.086). The average difference between K-ACT and C-ACT was stable before and after the application of TA (p = 0.85) but the variability of the differences significantly increased during cardiopulmonary bypass (p < 0.001).

CONCLUSIONS

Application of TA does not seem to differentially affect the mean C-ACT and K-ACT. No recommendation seems warranted to prefer one activator over the other in patients receiving TA.

Minimising intra-operative blood loss

Minimising intra-operative blood loss involves using many different approaches to the problem (Fig. 1), all of which have application for particular types of surgery. There is however a need for careful cooperation between haemotologist, surgeon and anaesthetist to ensure that this important goal is achieved.

[Does the time between preoperative interruption of aspirin intake and operation influence postoperative blood loss and transfusion requirement in coronary artery bypass graft?]

OBJECTIVE

Impact of the interval between interruption of aspirin intake and surgery on postoperative bleeding and transfusion in coronary artery bypass graft (CABG), with extracorporeal circulation (ECC).

STUDY DESIGN

Retrospective study.

PATIENTS AND METHODS

Four hundred and twelve patients having undergone CABG were retrospectively reviewed. Three groups were evaluated according to the length of the interval defined above: Group I (< 3 days), Group II (3-7 days), Group III (> 7 days or without aspirin intake). Postoperative blood loss at 3rd, 6th, 12th, and 24th hour and transfusion requirements were assessed for the 3 groups. Aprotinin (low dose, 2 M KIU) was systematically included in the priming of the ECC circuit.

RESULTS

There were no significant differences among groups for weight, size, duration of ECC, and number of bypasses. No significant correlation was noted among the 3 groups for postoperative blood loss and transfusion. Multivariate analysis showed that factors associated to a higher risk of excessive bleeding were ECC duration and number of arterial grafts. Factors associated with a higher risk of transfusion were: emergency, minimum patient temperature during ECC, weight and preoperative haemoglobin level. Aspirine intake was not associated with an increase of bleeding or transfusion.

CONCLUSION

Our study showed that in our practice using systematic low dose of aprotinin when priming the ECC circuit, aspirin did not significantly increase bleeding or transfusion requirements in CABG with ECC, whatever the interval between interruption of aspirin intake and surgery. Consequently, in our practice, aspirin intake is interrupted on hospitalisation, one day before surgery.

Systematic review of the use of fibrin sealant to minimize perioperative allogeneic blood transfusion

BACKGROUND

Fibrin sealants have become popular in improving perioperative haemostasis and reducing the need for allogeneic red cell transfusion.

METHODS

A systematic review of randomized controlled trials was conducted to examine the efficacy of fibrin sealants in reducing perioperative blood loss and allogeneic red blood cell transfusion. Studies were identified by computer searches of Medline, Embase, Current Contents, the Cochrane Library, manufacturer websites (to January 2001), and bibliographic searches of published articles. Trials were eligible for inclusion if they involved adult elective surgery and reported quantitative data on blood loss, the proportion of patients exposed to allogeneic red cell transfusion and/or the volume of blood transfused.

RESULTS

Twelve trials met the criteria for inclusion. Fibrin sealants reduced the rate of allogeneic blood transfusion (relative risk 0.40 (95 per cent confidence interval (c.i.) 0.26 to 0.61); five trials with 275 subjects) and reduced blood loss (weighted mean difference--151.68 (95 per cent c.i. - 251.91 to - 51.46) ml; seven trials with 391 subjects). Generally, the trials were small and of poor methodological quality.

CONCLUSION

Overall the results suggest that fibrin sealants are efficacious. Owing to lack of blinding, transfusion practices may have been influenced by knowledge of the patient's treatment status. This raises concern about blood transfusion practice as a response variable. Large methodologically rigorous trials of fibrin sealants with clinical outcomes are needed.

Multidisciplinary management of a Jehovah's Witness patient for the removal of a renal cell carcinoma extending into the right atrium

PURPOSE

To highlight the management of a Jehovah's witness surgical patient presenting for cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest.

CLINICAL FEATURES

A 47-yr-old male, Jehovah's Witness, with renal cell carcinoma was admitted for left radical nephrectomy and excision of tumour thrombus extending into the junction of the inferior vena cava (IVC) and right atrium (RA). The preoperative goals were to maximize red blood cell mass, delineate the extent of tumour extension and develop a surgical plan incorporating blood conservation strategies to minimize blood loss. A midline abdominal incision was made to optimize removal of the non-caval portion of the tumour from the intra-abdominal region. CPB and deep hypothermic circulatory arrest were instituted to aid in removing the tumour from the IVC and RA. Intraoperative blood conservation strategies included the use of acute normovolemic hemodilution, antifibrinolytics, cell salvage, point-of-care monitoring of heparin and protamine blood concentrations, leukocyte-depleting filter, and meticulous surgical techniques. The patient was successfully weaned from CPB and was transported to the cardiothoracic intensive care unit without complication. The patient was discharged home one week after the operation with a hemoglobin of 10.2 g x dL(-1) and a hematocrit of 31.2%.

CONCLUSION

Multiple blood conservation techniques were employed to manage this Jehovah's Witness patient through complex cardiac surgery, which was previously denied to him at other institutions. The successful outcome of this patient, while respecting the right to refuse allogeneic blood products, is a result of a multidisciplinary collaboration as well as the application of established blood conservation techniques.

Transfusion thresholds and other strategies for guiding allogeneic red blood cell transfusion

BACKGROUND

Most clinical practice guidelines recommend restrictive red cell transfusion practices with the goal of minimising exposure to allogeneic blood (from an unrelated donor). The purpose of this review is to compare clinical outcomes in patients randomised to restrictive versus liberal transfusion thresholds (triggers).

OBJECTIVES

To examine the evidence on the effect of transfusion thresholds, on the use of allogeneic and/or autologous blood, and the evidence for any effect on clinical outcomes.

SEARCH STRATEGY

Trials were identified by: computer searches of OVID Medline (1966 to December 2000), Current Contents (1993 to Week 48 2000), and the Cochrane Controlled Trials Register (2000 Issue 4). References in identified trials and review articles were checked and authors contacted to identify any additional studies.

SELECTION CRITERIA

Controlled trials in which patients were randomised to an intervention group or to a control group. Trials were included where the intervention groups were assigned on the basis of a clear transfusion "trigger", described as a haemoglobin (Hb) or haematocrit (Hct) level below which a RBC transfusion was to be administered.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed using criteria proposed by Schulz et al. (1995). Relative risks of requiring allogeneic blood transfusion, transfused blood volumes and other clinical outcomes were pooled across trials using a random effects model.

MAIN RESULTS

Ten trials were identified that reported outcomes for a total of 1780 patients. Restrictive transfusion strategies reduced the risk of receiving a red blood cell (RBC) transfusion by a relative 42% (RR=0.58: 95%CI=0.47,0.71). This equates to an average absolute risk reduction (ARR) of 40% (95%CI=24% to 56%). The volume of RBCs transfused was reduced on average by 0.93 units (95%CI=0.36,1.5 units). However, heterogeneity between these trials was statistically significant (p<0.00001) for these outcomes. Mortality, rates of cardiac events, morbidity, and length of hospital stay were unaffected. Trials were of poor methodological quality.

REVIEWER'S CONCLUSIONS

The limited published evidence supports the use of restrictive transfusion triggers in patients who are free of serious cardiac disease. However, most of the data on clinical outcomes were generated by a single trial. The effects of conservative transfusion triggers on functional status, morbidity and mortality, particularly in patients with cardiac disease, need to be tested in further large clinical trials. In countries with inadequate screening of donor blood the data may constitute a stronger basis for avoiding transfusion with allogeneic red cells.

Pre-operative autologous donation for minimising perioperative allogeneic blood transfusion

BACKGROUND

Public concerns regarding the safety of transfused blood have prompted re-consideration of the indications for the transfusion of allogeneic red cells (blood from an unrelated donor), and a range of techniques designed to minimise transfusion requirements.

OBJECTIVES

To examine the evidence for the efficacy of pre-operative autologous blood donation (PAD) in reducing the need for peri-operative allogeneic red blood cell (RBC) transfusion.

SEARCH STRATEGY

Articles were identified by: computer searches of OVID MEDLINE, EMBASE, and Current Contents (to March 2001) and web sites of international health technology assessment agencies (to January 2001). References in the identified trials were checked and authors contacted to identify additional studies.

SELECTION CRITERIA

Randomised controlled trials with a concurrent control group in which adult patients, scheduled for non-urgent surgery, were randomised to PAD, or to a control group who did not receive the intervention.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed using criteria proposed by Schulz et al (1995) and Jadad et al (1996). The principle outcomes were: the number of patients exposed to allogeneic red blood cells, and the amount of blood transfused. Other clinical outcomes are detailed in the review.

MAIN RESULTS

Overall PAD reduced the risk of receiving an allogeneic blood transfusion by a relative 63% (RR=0.37: 95%CI:0.26,0.54). The absolute reduction in risk of allogeneic transfusion was 43.8% (RD=-0.438: 95%CI: -0.607,-0.268). In contrast the results show that the risk of receiving any blood transfusion (allogeneic and/or autologous) is actually increased by pre-operative autologous blood donation (RR=1.29: 95%CI: 1.12,1.48). Trials were unblinded and allocation concealment was not described in 87.5% of the trials.

REVIEWER'S CONCLUSIONS

Although the trials of PAD showed a reduction in the need for allogeneic blood the methodological quality of the trials was poor and the overall transfusion rates (allogeneic and/or autologous) in these trials were high, and were increased by recruitment into the PAD arms of the trials. This raises questions about the true benefit of PAD. In the absence of large, high quality trials using clinical endpoints, it is not possible to say whether the benefits of PAD outweigh the harms.

Practical management of anticoagulation, bleeding and blood product support for cardiac surgery part two: Transfusion issues

We summarise recent advances in transfusion medicine applicable to cardiac surgery and cardiac transplantation. It is important that clinicians know the risks of blood transfusion in Australia. They should also be aware of the different types of transfusion reaction so that there is early recognition and investigation. Blood conservation strategies including acceptance of normovolaemic anaemia in clinically stable patients are important in reducing the requirement for red cell transfusion. Cytomegalovirus (CMV) seronegative blood products are recommended for heart transplant recipients with no evidence of prior CMV infection. Leucodepletion of units of unknown CMV status reduces the risk of CMV infection and are an acceptable alternative when seronegative units are unavailable. Leucodepletion of cellular blood products has been shown to reduce infection rates postoperatively in a large trial involving cardiac surgical patients. Further studies are needed to confirm this promising finding. Irradiation of blood products eliminates the risk of transfusion-associated graft versus host disease. Routine preoperative screening for cold agglutinins is no longer recommended.

Systematic elucidation of effects of tranexamic acid on fibrinolysis and bleeding during and after cardiopulmonary bypass surgery

The aim of this study was to systematically elucidate the effects of tranexamic acid on fibrinolysis and bleeding during and after cardiopulmonary bypass (CPB) surgery. Twenty-two patients undergoing CPB surgery were randomized to receive 100 mg/kg tranexamic acid or an equal volume of saline after anesthesia induction and prior to skin incision. Plasma levels of tissue plasminogen activator (t-PA) antigen and activity, crosslinked fibrin degradation products (D-dimer), alpha2-antiplasmin-plasmin complex, and plasminogen activator inhibitor-1 (PAI-1) antigen were measured. Blood samples were obtained after induction of anesthesia, before, during, and after CPB, at the end of surgery, and the next morning after surgery. Intraoperative and postoperative blood loss during 24 h after surgery was recorded. Patients' demographics were similar between the two groups. No patients suffered from thrombotic complications after surgery. In the tranexamic acid group, fibrinolytic activity and secondary fibrinolysis as measured by t-PA activity and D-dimer were markedly suppressed during CPB surgery (P=.042 and P=.015, respectively). Decreased fibrinolytic activity and fibrinolysis were accompanied by reduction of perioperative bleeding in the tranexamic acid group. We could also find a good positive correlation between the peak levels of t-PA activity and D-dimer (r(2)=.4203, P=.0011). No differences in the t-PA antigen, PAI-1 antigen release, and plasmin inhibition by alpha2-antiplasmin were apparent between the two groups. In a randomized, prospective trial of patients undergoing CPB surgery, we demonstrated that the synthetic antifibrinolytic drug tranexamic acid effectively suppresses fibrinolysis by inhibiting t-PA and plasmin activity with clear reduction of perioperative blood loss. While tranexamic acid had no effects on the other important fibrinolytic inhibitors like PAI-1 and alpha2-antiplasmin.

A standardized multidisciplinary approach reduces the use of allogeneic blood products in patients undergoing cardiac surgery

PURPOSE

Individual and institutional practices remain an independent predictor factor for allogeneic blood transfusion. Application of a standardized multidisciplinary transfusion strategy should reduce the use of allogeneic blood transfusion in major surgical patients.

METHODS

This prospective non randomized observational study evaluated the effects of a standardized multidisciplinary transfusion strategy on allogeneic blood products exposure in patients undergoing non-emergent cardiac surgery. The developed strategy involved a standardized blood conservation program and a multidisciplinary allogeneic blood transfusion policy based mainly on clinical judgement, not only on a specific hemoglobin concentration. Data obtained in a first group including patients operated from September 1997 to August 1998 (Group pre: n=321), when the transfusion strategy was progressively developed, were compared to those obtained in a second group, including patients operated from September 1998 to August 1999 (Group post: n=315) when the transfusion strategy was applied uniformly.

RESULTS

Patient populations and surgical procedures were similar. Patients in Group post underwent acute normovolemic hemodilution more frequently, had a higher core temperature at arrival in the intensive care unit and presented lower postoperative blood losses at day one. Three hundred forty units of packed red blood cells were transfused in 33% of the patients in Group pre whereas 161 units were transfused in 18% of the patients in Group post (P <0.001). Pre- and postoperative hemoglobin concentrations, mortality and morbidity were not different among groups.

CONCLUSION

Development of a standardized multidisciplinary transfusion strategy markedly reduced the exposure of cardiac surgery patients to allogeneic blood.

Hemostatic Abnormalities in Cardiopulmonary Bypass: Pathophysiologic and Transfusion Considerations

Cardiac surgical procedures typically use cardiopulmo nary bypass (CPB), a technique that diverts blood from the heart and lungs, where it is oxygenated and pumped back into the circulation. CPB is associated with significant pathophysiologic changes leading to an increased bleeding risk. Bleeding during CPB occurs for multiple reasons; the primary reason is the expo sure of blood to the material components of the CPB system, with intense systemic coagulation and platelet, fibrinolytic, and endothelial activation. To counteract the coagulation activation, extremely high levels of heparin anticoagulation are required to prevent sys temic thrombosis. Thrombin generation through tissue factor pathway activation is now thought to be the predominant mechanism of coagulation activation in CPB. The stimulus for tissue factor exposure to blood is thought to be a systemic activation of tissue factor on monocytes and endothelial cells caused by comple ment activation by the CPB materials and circulating inflammatory mediators. Despite improvements in the CPB system, surgical techniques, and blood conserva tion methods, the demand for blood in such procedures remains sustantial. Optimal blood use can be achieved by combining blood conservation measures with the transfusion of blood components according to strict guidelines. Blood is a limited resource and must be used wisely and cautiously. The risks and costs associ ated with transfusion are compelling reasons to mini mize unnecessary exposure to blood. However, the bene fits of transfusion are well established, and the risks are reasonably low. New developments in the surfaces of the CPB system, use of established and new protease inhibitors, and new blood conservation measures offer promise in decreasing the bleeding risk associated with CPB.

Antifibrinolytic agents and desmopressin as hemostatic agents in cardiac surgery

OBJECTIVE

To review the use of systemic hemostatic medications for reducing bleeding and transfusion requirements with cardiac surgery.

DATA SOURCES

Articles were obtained through computerized searches involving MEDLINE (from 1966 to September 2000). Additionally, several textbooks containing information on the diagnosis and management of bleeding associated with cardiac surgery were reviewed. The bibliographies of retrieved publications and textbooks were reviewed for additional references.

STUDY SELECTION

Due to the large number of randomized investigations involving systemic hemostatic medications for reducing bleeding associated with cardiac surgery, the article selection process focused on recent randomized controlled trials, metaanalyses and pharmacoeconomic evaluations.

DATA EXTRACTION

The primary outcomes extracted from the literature were blood loss and associated transfusion requirements, although other outcome measures such as mortality were extracted when available.

DATA SYNTHESIS

Although the majority of investigations for reducing cardiac bleeding and transfusion requirements have involved aprotinin, evidence from recent meta-analyses and randomized trials indicates that the synthetic antifibrinolytic agents, aminocaproic acid and tranexamic acid, have similar clinical efficacy. Additionally, aminocaproic acid (and to a lesser extent tranexamic acid) is much less costly. More comparative information of hemostatic agents is needed retative to other outcomes (eg., reoperation rates, myocardial infarction, stroke). There is insufficient evidence to recommend the use of desmopressin for reducing bleeding and transfusion requirements in cardiac surgery, although certain subsets of patients may benefit from its use.

CONCLUSIONS

Of the medications that have been used to reduce bleeding and transfusion requirements with cardiac surgery, the antifibrinolytic agents have the best evidence supporting their use. Aminocaproic acid is the least costly therapy based on medication costs and transfusion requirements.

Monitoring the Hematologic Complications of Cardiopulmonary Bypass

Patients undergoing cardiopulmonary bypass (CPB) procedures have a variety of hemostatic defects that lead to bleeding and the frequent need for transfusion of allogeneic blood products. Dilution of the patient's blood volume by the extracorporeal circuit priming so lution causes depletion of platelets and coagulation factor levels. Contact of blood with the extracorporeal circuit induces a hemorrhagic diathesis through a vari ety of mechanisms. Contact activation causes the for mation of kallikrein, bradykinin, and complement acti vation, leading to a whole-body inflammatory reaction. Intrinsic coagulation is stimulated, leading to subse quent activation of the fibrinolytic system. Platelet dys function caused by the effects of the extracorporeal circuit on platelet membrane integrity and the effects of circulating platelet inhibitors have also been described. The use of high-dose heparin for CPB mitigates these effects but does not completely eliminate them. Prota mine, administered to antagonize heparin's effects, has antiplatelet properties and anticoagulant effects when given in excess. Because of the numerous hemostatic insults incurred during and after CPB, complex moni toring techniques are necessary to ensure adequate anticoagulation, adequate heparin neutralization, and normal platelet function. Coagulation monitoring has allowed more specific identification of particular distur bances of hemostasis and has been linked with a reduc tion in hemorrhagic complications after CPB. Copyright © 2001 by W.B. Saunders Company.

Influence of hypotensive and normotensive anesthesia on platelet aggregability and hemostatic markers in orthognathic surgery

This prospective randomized study investigated the influence of normotensive and hypotensive general anesthesia on platelet aggregability, intraoperative blood loss and parameters of plasmatic coagulation during extensive orthognathic surgery. A total of 30 patients were randomly allocated for either normotensive anesthesia maintained by continuous infusion of propofol and remifentanil (NORMO, n=10) or hypotensive anesthesia, whereby hypotension was induced by increasing the infusion rate of remifentanil (HYPO-R, n=10) or by administration of nitroglycerin (HYPO-N, n=10). Whole blood platelet aggregability was significantly reduced during hypotension compared to normotensive anesthesia (P<.01, HYPO-N and HYPO-R vs. NORMO). Mean arterial blood pressure during hypotension correlated well with adenosinediphosphate- (R=.712, P<.001) and collagen-induced platelet aggregability (R=.685, P<.001). Within hypotensive study groups, postoperative fibrinogen levels were significantly different, whereas intraoperative platelet aggregability, postoperative platelet count, prothrombin time, activated partial thromboplastin time and antithrombin levels were not different. Normotensive anesthesia, however, caused significant decreases in platelet count (-29%), prothrombin time (-24%), fibrinogen (-41%) and antithrombin (-28%) and a significant prolongation in activated partial thromboplastin time (+21%) and thrombin time (+18%). There was a trend to reduced intraoperative blood loss in hypotensive study groups; however, differences were not significant. In conclusion, induced hypotension--independent of substances used for induction of hypotension--reduces intraoperative platelet aggregability, subsequently protecting the coagulation system against subclinical consumption coagulopathy. Induced hypotension-caused platelet dysfunction does not lead to an increased intraoperative blood loss, but quite on the contrary shows a trend to reduced intraoperative blood loss, possibly by preventing platelet-induced subclinical consumption coagulopathy.

Blood loss in elective coronary artery surgery: a comparison of centrifugal versus roller pump heads during cardiopulmonary bypass

OBJECTIVES

To compare the effects of centrifugal pumps versus roller pumps for cardiopulmonary bypass (CPB) in routine cardiac surgery on hematologic parameters in the context of modern practice.

DESIGN

Prospective, randomized, partially blinded.

SETTING

University teaching hospital.

PARTICIPANTS

Elective coronary artery surgery patients (n = 113)

INTERVENTION

Patients were randomized to be perfused with either a roller head (group R, n = 56) or a centrifugal head (group C, n = 57) pump. Patients received epsilon-aminocaproic acid before and during CPB. Core body temperatures were allowed to drift down to approximately 32 degrees C.

MEASUREMENTS AND MAIN RESULTS

Postoperative chest tube blood loss, blood product requirements, hemoglobin, and platelet counts were assessed. There were no significant differences in preoperative or intraoperative parameters, including CPB time, complexity of procedure, and minimum core temperature. There were the expected reductions in hemoglobin and platelet levels post-CPB in both groups to a similar extent. Chest tubes remained in situ for similar durations, and the final volume of drainage was not significantly different (group C, 1300 +/- 92 mL; group R 1117 +/- 83 mL; p = 0.14). Allogeneic blood was given to 23% of patients in group C and 18% in group R (p = 0.63). Aspirin was associated with an increase in early chest tube drainage.

CONCLUSIONS

In this surgical and perfusion environment, the authors were unable to show an advantage, from the hematologic point of view, in the routine use of a centrifugal pump head in elective coronary artery surgical patients. The use of antifibrinolytic agents and mild hypothermia may have effects on hemostasis that overshadow the influence of pump head design in this type of surgery.

The efficacy of antifibrinolytics in the reduction of blood loss during complex adult reconstructive spine surgery

STUDY DESIGN

Controlled study to assess the efficacy of aprotinin and Amicar in reducing blood loss during complex spinal fusions.

OBJECTIVES

To compare blood loss and the clotting profile with a thromboelastogram in patients with spinal deformities undergoing sequential anterior and posterior spinal fusions treated intraoperatively with either aprotinin or Amicar.

SUMMARY OF BACKGROUND DATA

Spinal fusion for correction of adult spinal deformities is associated with large blood losses despite the implementation of multiple factors to reduce this blood loss. The antifibrinolytics aprotinin and Amicar have both been shown to reduce blood loss in other surgical procedures with the potential for large blood loss. Hence, we compared their efficacy for reducing blood loss in complex spinal fusions.

METHODS

Sixty patients for elective sequential anteroposterior thoracolumbosacral fusions were randomly assigned to three groups: control, aprotinin, and Amicar. Patients were assessed for blood loss, transfusion requirements, postoperative complications, and coagulation profile using a thromboelastogram.

RESULTS

The study demonstrated a significant reduction in total blood loss (aprotinin 3628 mL, Amicar 4056 mL, control 5181 mL) and transfusion requirements using the half-dose aprotinin regimen compared with Amicar or control. Aprotinin also preserved the thromboelastogram mean clot formation time, clot strength, and clotting index compared with Amicar or control.

CONCLUSIONS

For complex spinal operations with large blood losses, the half-dose aprotinin regimen will reduce blood loss and the need for blood components and may have a role in reducing postoperative lung injury.

The Effect of epsilon-aminocaproic acid on perioperative blood loss in patients with idiopathic scoliosis undergoing posterior spinal fusion: a preliminary prospective study

STUDY DESIGN

A prospective study evaluating the efficacy of epsilon-aminocaproic acid (EACA) in decreasing perioperative blood loss in idiopathic scoliosis.

OBJECTIVES

To compare the perioperative blood loss and need for blood replacement in two groups of patients undergoing surgery for idiopathic scoliosis. One group received intraoperative EACA; the other did not and served as controls.

SUMMARY OF BACKGROUND DATA

Excessive blood loss increases the operative time, risk for blood product disease transmission, postoperative complications, and costs associated with posterior spinal fusion and instrumentation. EACA is an antifibrinolytic agent that has been shown to be effective in reducing perioperative blood loss during pediatric cardiothoracic surgical procedures. We hypothesized that it would also be effective in lowering blood loss during posterior spinal fusion for idiopathic scoliosis.

METHODS

We compared the perioperative blood loss of 28 consecutive pediatric patients with idiopathic scoliosis who underwent posterior spinal fusion and received intraoperative EACA with 31 consecutive patients who did not receive this medication and served as a control group.

RESULTS

The patients in both groups were similar. Patients in the EACA group demonstrated statistically significant decreases in total estimated perioperative blood loss and the need for autologous blood transfusion. The patients in the EACA group had no intraoperative or postoperative complications related to the use of this medication.

CONCLUSIONS

Based on these preliminary findings, we believe that EACA is helpful in decreasing blood loss in patients undergoing posterior spinal fusion and instrumentation, and may decrease the number of autologous units needed to maintain safe perioperative hemoglobin levels, thereby improving safety and lowering cost associated with scoliosis surgery.

Is tranexamic acid safe in patients undergoing coronary endarterectomy?

BACKGROUND

Patients undergoing coronary endarterectomy during coronary artery bypass grafting (CABG) are at increased risk of perioperative myocardial infarction due to coronary intimal disruption. Data assessing the safety of the antifibrinolytic drug tranexamic acid (TA) in patients undergoing this procedure are lacking.

METHODS

From September 1997 to December 1999, 221 patients underwent nonemergency primary CABG with endarterectomy of the right coronary artery alone in 149, the left anterior descending in 35, or both right and left anterior descending in 27. TA was administered intraoperatively to 87 patients (TA group: average total dose 62 +/- 4.4 mg/kg; range 20 to 109 mg/kg), and was not administered to 134 patients (No TA group).

RESULTS

The patient characteristics of the 2 groups were similar. In-hospital mortality consisted of 2 patients in the TA group and 4 patients in the No TA group. Perioperative myocardial infarction rates were 2% and 5% in the TA and No TA groups, respectively (p = 0.49). The relative risk for any type of perioperative cardiac ischemic event in the TA group versus the No TA group was 0.77 (95% CI; 0.4, 1.2). Patients in the TA group had a significant reduction in postoperative chest tube drainage (685 versus 894 mL in the TA versus No TA groups, respectively) and in the use of fresh-frozen plasma (p = 0.03).

CONCLUSIONS

These results suggest that the clinical effectiveness of tranexamic acid in reducing postoperative blood loss in patients undergoing coronary endarterectomy is not associated with a higher incidence of myocardial ischemia-related complications.

Plasma tranexamic acid concentrations during cardiopulmonary bypass

Although tranexamic acid is used to reduce bleeding after cardiac surgery, there is large variation in the recommended dose, and few studies of plasma concentrations of the drug during cardiopulmonary bypass (CPB) have been performed. The plasma tranexamic acid concentration reported to inhibit fibrinolysis in vitro is 10 microg/mL. Twenty-one patients received an initial dose of 10 mg/kg given over 20 min followed by an infusion of 1 mg. kg(-1). h(-1) via a central venous catheter. Two patients were removed from the study secondary to protocol violation. Perioperative plasma tranexamic acid concentrations were measured with high-performance liquid chromatography. Plasma tranexamic acid concentrations (microg/mL; mean +/- SD [95% confidence interval]) were 37.4 +/- 16.9 (45.5, 29.3) after bolus, 27.6 +/- 7.9 (31.4, 23.8) after 5 min on CPB, 31.4 +/- 12.1 (37.2, 25.6) after 30 min on CPB, 29.2 +/- 9.0 (34.6, 23.8) after 60 min on CPB, 25.6 +/- 18.6 (35.1, 16.1) at discontinuation of tranexamic acid infusion, and 17.7 +/- 13.1 (24.1, 11.1) 1 h after discontinuation of tranexamic acid infusion. Four patients with renal insufficiency had increased concentrations of tranexamic acid at discontinuation of the drug. Repeated-measures analysis revealed a significant main effect of abnormal creatinine concentration (P = 0.02) and time (P < 0.001) on plasma tranexamic acid concentration and a significant time x creatinine concentration interaction (P < 0.001).

IMPLICATIONS

A 10 mg/kg initial dose of tranexamic acid followed by an infusion of 1 mg.kg(-1).h(-1)produced plasma concentrations throughout the cardiopulmonary bypass period sufficient to inhibit fibrinolysis in vitro. The dosing of tranexamic acid may require adjustment for renal insufficiency.

Utilization of technologies to reduce allogeneic blood transfusion in the United States

Concern over safety of the blood supply has led to the use of technologies to reduce allogeneic blood transfusion. The objective of this research was to determine the utilization of these technologies in the United States. We evaluated the following techniques: preoperative autologous donation (PAD), cell salvage (CS) and acute normovolemic haemodilution (ANH); and the following pharmaceuticals: aprotinin (APR), epsilon-aminocaproic acid (EACA), tranexamic acid (TXA), desmopressin (DDAVP) and recombinant human erythropoietin (EPO). In 1997, we conducted a cross-sectional mail survey of service chiefs at 1000 US hospitals randomly selected and stratified by status as a provider of open-heart surgery, geographical location and hospital bed size. Sixty-nine per cent (690) of hospitals responded to at least one of the four surveys sent to each hospital. Hospitals reported use of techniques more than pharmaceuticals (P < 0.001); PAD (83%, n = 206) and CS (82% n = 420) were used most frequently. Lack of familiarity was the most common reason cited for infrequent use of pharmaceuticals. Organizational characteristics (e.g. provision of open-heart surgery, size, geographical location, teaching status and type of hospital) were differentially associated with technology use. There is greater use of techniques than pharmaceuticals in US hospitals to reduce the need for allogeneic blood in the peri-operative setting. Providing open-heart surgery is strongly associated with the utilization of these technologies.

Examining the evidence in anesthesia literature: a critical appraisal of systematic reviews

Systematic reviews are structured reviews that use scientific strategies to reduce bias in the collection, appraisal, and interpretation of relevant studies. We undertook a systematic review of published systematic reviews in perioperative medicine to summarize the areas currently covered by this type of literature, to evaluate the quality of systematic reviews in this field, and to assess some of the methodologic and reporting issues that are unique to systematic reviews. Computerized bibliographic databases, citation review, and hand searches were performed to identify eligible articles. Quality was assessed using the Overview Quality Assessment Questionnaire. Eight-two systematic reviews were found. Reviews in perioperative medicine tended to evaluate prophylactic or therapeutic interventions. No differences were seen in quality between reviews published in anesthesia and nonanesthesia journals. Nearly half of all systematic reviews had only minor or minimal flaws; however, methods can be improved with expanded search strategies, use of least two reviewers to assess each study, use of validated methods to evaluate quality, and assessment of potential sources of bias.

IMPLICATIONS

The quality of systematic reviews relating to perioperative medicine was examined systematically and found to be similar in quality to those in other specialties. Adoption of recently published criteria on writing and methods could further improve this type of literature.

Anti-fibrinolytic use for minimising perioperative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood have prompted re-consideration of the use of allogeneic (blood from an unrelated donor) blood transfusion.

OBJECTIVES

To assess the effects of the anti-fibrinolytic drugs aprotinin, tranexamic acid, and epsilon aminocaproic acid, on peri-operative red blood cell (RBC) transfusion.

SEARCH STRATEGY

We searched MEDLINE (to May 1998), EMBASE (to December 1997), web sites of international health technology assessment agencies (to May 1998). References in identified trials and review articles were checked and authors contacted to identify any additional studies.

SELECTION CRITERIA

Randomised controlled trials of anti-fibrinolytic drugs in adults scheduled for non-urgent surgery.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data.

MAIN RESULTS

We found 61 trials of aprotinin (7027 participants). Aprotinin reduced the rate of RBC transfusion by a relative 30% (RR=0.70: 95%CI: 0.64 to 0.76). The average absolute risk reduction (ARR) was 20.4% (95%CI: 15.6% to 25.3%). On average, aprotinin use saved 1.1 units of RBC (95%CI: 0.69 to 1.47) in those requiring transfusion. Aprotinin also significantly reduced the need for re-operation due to bleeding (RR=0.40: 95%CI: 0.25 to 0.66). We found 18 trials of tranexamic acid (TXA) (1,342 participants). TXA reduced the rate of RBC transfusion by a relative 34% (RR=0.66: 95%CI: 0.54 to 0.81). This represented an ARR of 17.2% (95%CI: 8.7% to 25.7%). TXA use resulted in a saving of 1.03 units of RBC (95%CI: 0.67 to 1.39) in those requiring transfusion. We found four trials of epsilon aminocaproic acid (EACA) (208 participants). EACA use resulted in a statistically non-significant reduction in RBC transfusion (RR=0.48: 95%CI: 0.19 to 1.19). Comparisons between agents Eight trials made 'head-to-head' comparisons between TXA and aprotinin. There was no significant difference between the two drugs in the rate of RBC transfusion: RR=1.21 (95%CI: 0.83 to 1.76) for TXA compared to aprotinin. Adverse Effects Aprotinin did not seem to be associated with an excess risk of adverse effects, including thrombo-embolic events (thrombosis RR=0.64: 95%CI: 0.31 to 1.31) and renal failure (RR=1.19: 95%CI: 0.79 to 1.79). Fewer data were available for TXA and EACA.

REVIEWER'S CONCLUSIONS

From this review it appears that aprotinin reduces the need for red cell transfusion, and the need for re-operation due to bleeding, without serious adverse effects. However, there was significant heterogeneity in trial outcomes, and some evidence of publication bias. Similar trends were seen with TXA and EACA, although the data were rather sparse. The poor evaluation of these latter drugs is unfortunate as results suggest they may be equally as effective as aprotinin, but are significantly cheaper. The evidence reviewed here supports the use of aprotinin in cardiac surgery. Further small trials of this drug are not warranted. Future trials should be large enough to compare the efficacy and cost-effectiveness of aprotinin with that of TXA and EACA.

Desmopressin for minimising perioperative allogeneic blood transfusion

BACKGROUND

Public concerns regarding the safety of transfused blood have prompted re-consideration of the use of allogeneic (from an unrelated donor) red blood cell (RBC) transfusion, and a range of techniques designed to minimise transfusion requirements.

OBJECTIVES

To examine the evidence for the efficacy of desmopressin (1-deamino-8-D-arginine-vasopressin), in reducing perioperative blood loss and the need for red cell transfusion in patients who do not have congenital bleeding disorders.

SEARCH STRATEGY

Articles were identified by: computer searches of OVID MEDLINE, EMBASE, and Current Contents (to August 2000) and web sites of international health technology assessment agencies (to May 1998). References in the identified trials and review articles were checked and authors contacted to identify additional studies.

SELECTION CRITERIA

Randomised controlled parallel group trials in which adult patients, scheduled for non-urgent surgery, were randomised to DDAVP, or to a control group, who did not receive the intervention.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed using criteria proposed by Schulz et al. (1995) and Jadad et al. (1996). The principal outcomes were: the number of patients exposed to red cells, and the amount of blood transfused. Other clinical outcomes are detailed in the review.

MAIN RESULTS

Fourteen trials of DDAVP (N=1034) reported data on the proportion of patients exposed to allogeneic RBC transfusion. In subjects treated with DDAVP the relative risk of exposure to peri-operative allogeneic blood transfusion was 0.98 (95%CI: 0.88 to 1.10) compared with control. In DDAVP-treated patients the relative risk of requiring re-operation due to bleeding was 0.56 (95%CI: 0.18 to 1.73). There was no statistically significant effect overall for mortality and non-fatal myocardial infarction in DDAVP-treated patients compared with control (RR=1.53: 95%CI: 0.58 to 4.05) and (RR=1.52: 95%CI: 0.67 to 3.49) respectively.

REVIEWER'S CONCLUSIONS

There is no convincing evidence that desmopressin minimises perioperative allogeneic RBC transfusion in patients who do not have congenital bleeding disorders. These data suggest that there is no benefit of using DDAVP as a means of minimising perioperative allogeneic RBC transfusion. This meta-analysis had 90% power to detect a relative risk reduction of at least 17% for receiving a red cell transfusion at alpha = 0.05 (two-sided).

Giant bronchial carcinoid tumors: a multidisciplinary approach

BACKGROUND

Bronchial carcinoid tumors account for approximately 2% of all lung tumors. Although they were considered benign lesions, they are now categorized malignant, occasionally with poor prognosis. The clinical symptoms can be highly variable and are often present for many years before diagnosis. Whereas some carcinoids are entirely asymptomatic, others are accompanied by carcinoid or paraneoplastic syndromes.

METHODS

We describe the multidisciplinary management of a 34-year-old female patient with a massive actively secreting bronchial carcinoid tumor of the right lung. Furthermore, we provide a review of the literature regarding the operative treatment and the perioperative management of pulmonary carcinoid tumors with respect to surgical, anesthetic, radiologic, and pathologic considerations.

RESULTS

In the reported case, the first symptoms were chronic watery diarrhea, skin flushing, progressive shortness of breath, and increasing right shoulder pain. When the patient initially presented at our institution, the tumor had already reached an enormous size and it involved the right and left atrium as well as the atrial septum. Using an evidence-based, multidisciplinary approach the patient was treated successfully with extended surgical resection.

CONCLUSIONS

Carcinoid tumors are potentially curable even if they reach a significant size and thus an aggressive strategy is warranted. The management of such cases requires careful investigation, planning, and treatment with collaborative expertise provided by a multidisciplinary team. We demonstrated that this approach can lead to a favorable outcome in what first appeared to be a formidable and unresectable tumor.

Role of aprotinin in the management of patients during and after cardiac surgery

Management of patients undergoing cardiac surgery has evolved in recent years as more is understood about the physiological changes and responses that occur during and after cardiopulmonary bypass (CPB). In particular, our understanding of the mechanisms involved in haemostasis and in the inflammatory response to bypass surgery, has allowed significant refinements in patient management. Improvements in the pharmacological conservation of blood loss have been striking, particularly with the development of the serine protease inhibitor, aprotinin (Trasylol, Bayer). Aprotinin represents a significant improvement, especially for patients at high risk, since it reduces the need for allogeneic and (sometimes scarce) blood products. However, in view of its cost, making an appropriate selection of patients most at risk of serious blood loss is a major consideration in the use of aprotinin. While its mechanisms of action are not well understood, the use of aprotinin also appears to reduce inflammatory response to CPB.

Management approaches to platelet-related microvascular bleeding in cardiothoracic surgery

Patients undergoing cardiac surgery with cardiopulmonary bypass are at increased risk for microvascular bleeding that requires perioperative transfusion of blood components. Platelet-related defects have been shown to be the most important hemostatic abnormality in this setting. The exact association between preoperative use of potent platelet inhibitors and either bleeding or transfusion in patients undergoing cardiac surgical procedures is currently being defined. Laboratory evaluation of platelets and coagulation factors can facilitate the optimal administration of pharmacologic and transfusion-based therapy. However, their turnaround time makes laboratory-based methods impractical for concurrent management of surgical patients, which has led many investigators to study the role of point-of-care coagulation tests in this setting. Use of point-of-care tests of hemostatic function can optimize the management of excessive bleeding and reduce transfusion. Accordingly, point-of-care tests that assess platelet function may also identify patients at risk for acquired, platelet-related bleeding. The ability to reduce the unnecessary use of blood products and to decrease operative time or reexploration rates has important consequences for blood inventory, blood costs, and overall health care costs.

Prostaglandin E(1) does not influence plasmatic coagulation, hepatic synthesis, or postoperative blood loss in patients after coronary-artery bypass grafting

STUDY OBJECTIVE

To assess whether postoperatively administered prostaglandin E1 (PGE1) might prevent bleeding in patients after coronary artery bypass grafting (CABG).

DESIGN

Prospective, randomized, placebo-controlled trial.

SETTING

University-affiliated hospital.

PATIENTS

49 patients scheduled for elective CABG surgery.

INTERVENTIONS

The PGE1 group received intravenous PGE(1) up to 15 ng/kg/min for 72 hours after surgery, whereas the placebo group received isotonic saline for the same time period.

MEASUREMENTS AND MAIN RESULTS

Nine patients (4 in the PGE1 group vs. 5 in the placebo group) had to be excluded because of hemodynamic instability, and 1 in the placebo group because of gastric bleeding. In the remaining 39 patients (20 vs. 19), no significant differences with regard to hemoglobin levels or platelet count could be observed. There was no significant difference between the groups concerning the amount of packed red blood cells, platelet concentrates, or fresh frozen plasma transfused. No significant differences could be observed regarding laboratory markers of coagulation activation or hepatic synthesis either.

CONCLUSIONS

PGE1 did not prevent coagulation disturbances and blood loss when administered postoperatively in patients undergoing CABG. The absence of these expected effects might be explained by the concomitant administration of acetylsalicylic acid, whose antiaggregatory acivity seems to exceed the effects of PGE1.

Cost effectiveness of epoetin-alpha to augment preoperative autologous blood donation in elective cardiac surgery

OBJECTIVE

The objective of this study was to assess the cost effectiveness of using epoetin-alpha (erythropoietin) to augment preoperative autologous donation (PAD) of blood prior to elective cardiac surgery.

DESIGN AND SETTING

We designed a decision-analytic model incorporating the risk of receiving allogeneic blood, the costs of blood products, the likelihood of developing transfusion-related diseases, the costs of transfusion-related diseases and their impact on life expectancy, and the effect of epoetin-alpha on the probability of transfusion.

INTERVENTIONS

The efficacy of epoetin-alpha was derived from data from a meta-analysis of published randomised trials comparing the use of epoetin-alpha to augment PAD with the use of PAD alone. Estimates for the other parameters were obtained by a systematic review of the literature.

MAIN OUTCOME MEASURES AND RESULTS

The use of epoetin-alpha reduced the proportion of patients receiving allogeneic transfusions by 60% (from 31.6 to 12.7%). However, this led to only a modest benefit of 0.000035 life years gained per patient and an incremental cost per life year gained of $Can44.6 million (1998 Canadian dollars). A detailed sensitivity analysis confirmed that the cost-effectiveness ratio was larger than that which is generally considered acceptable.

CONCLUSIONS

Our study indicates that the use of epoetin-alpha to reduce perioperative allogeneic transfusions in cardiac surgery is not cost effective.

Use of interventions to minimise perioperative allogeneic blood transfusion in Australia. A survey by the International Study of Perioperative Transfusion (ISPOT) Study Group

OBJECTIVE

To investigate use of interventions to minimise need for perioperative transfusion of allogeneic blood in surgical units in Australia.

DESIGN

Two questionnaire-based surveys of practice.

SETTING

All hospitals in Australia, 1996-1997.

PARTICIPANTS

Survey 1: all Australian hospitals that have at least 50 beds and undertake surgery; Survey 2: surgical units identified as using the interventions.

MAIN OUTCOME MEASURES

Reported rates of use of the various interventions (preoperative autologous donation, acute normovolaemic haemodilution [ANH], cell salvage, and drugs); use of guidelines; and perceptions about the appropriateness of current levels of use.

RESULTS

Survey 1 was returned by 349 of 400 hospitals (87%) and Survey 2 by 324 of 578 surgical units (56%). Preoperative autologous donation was most widely used (70% of hospitals), most commonly in units performing orthopaedic or vascular surgery (65% and 37%, respectively). Cell salvage and ANH were used by 27% and 24% of hospitals, respectively, most often in units performing cardiothoracic (40% and 44%, respectively) and vascular surgery (29% and 15%, respectively). These three interventions were used significantly more in private than in public hospitals (P < 0.05). Use of printed guidelines was uncommon. Respondents considered that autologous transfusion techniques should be used more widely because of their perceived efficacy and concerns about safety of allogeneic blood. Perceived barriers to greater use included lack of surgeon or physician interest, uncertain scheduling of surgery in public hospitals and cost (cell salvage). Drugs to minimise blood loss were used by fewer than 10% of hospitals.

CONCLUSIONS

Interventions to minimise the need for perioperative allogeneic blood transfusion (apart from drugs) are widely used in Australia. However, enthusiasm for intraoperative techniques of re-infusing autologous blood needs to be assessed against the evidence of their efficacy and cost-effectiveness.

Aprotinin and tranexamic acid for high transfusion risk cardiac surgery

BACKGROUND

Studies have shown that aprotinin and tranexamic acid can reduce postoperative blood loss after cardiac operation. However, which drug is more efficacious in a higher risk surgical group of patients, has yet to be defined in a randomized study.

METHODS

With informed consent, 80 patients undergoing elective high transfusion risk cardiac procedures (repeat sternotomy, multiple valve, combined procedures, or aortic arch operation) were randomized in a double-blind fashion, to receive either high dose aprotinin or tranexamic acid. Patient and operative characteristics, chest tube drainage and transfusion requirements were recorded.

RESULTS

There was no significant difference between the 2 treatment groups with respect to age, cardiopulmonary bypass time, complications (myocardial infarction, stroke, death), chest tube drainage (6, 12, or 24 hours), blood transfusions up to 24 hours postoperatively, total allogeneic blood transfusions for entire hospital stay, or induction/postoperative hemoglobin levels. However, multiple regression analysis revealed a positive relationship between cardiopulmonary bypass time and 24 hour blood loss in the tranexamic acid group (p = 0.001), unlike the aprotinin group where 24 hour blood loss is independent of cardiopulmonary bypass time (p = 0.423).

CONCLUSIONS

Overall, there was no significant difference in blood loss, or transfusion requirements, when patients received either aprotinin or tranexamic acid for high transfusion risk cardiac operation. Aprotinin, when given as an infusion in a high-dose regimen, was able to negate the usual positive effect of cardiopulmonary bypass time on chest tube blood loss.

Pharmacological strategies to decrease excessive blood loss in cardiac surgery: a meta-analysis of clinically relevant endpoints

BACKGROUND

Excessive bleeding may complicate cardiac surgery, and is associated with increased morbidity and mortality. Pharmacological strategies to decrease perioperative bleeding have been investigated in a large number of controlled trials, most of which have shown a decrease in blood loss. However, most studies lacked sufficient power to detect a beneficial effect on clinically more relevant outcomes. We did a meta-analysis of all randomised, controlled trials of the three most frequently used pharmacological strategies to decrease perioperative blood loss (aprotinin, lysine analogues [aminocaproic acid and tranexamic acid], and desmopressin).

METHODS

Studies were included if they reported at least one clinically relevant outcome (mortality, rethoracotomy, proportion of patients receiving a transfusion, or perioperative myocardial infarction) in addition to perioperative blood loss. In addition, a separate meta-analysis was done for studies concerning complicated cardiac surgery.

FINDINGS

We identified 72 trials (8409 patients) that met the inclusion criteria. Treatment with aprotinin decreased mortality almost two-fold (odds ratio 0.55 [95% CI 0.34-0.90]) compared with placebo. Treatment with aprotinin and with lysine analogues decreased the frequency of surgical re-exploration (0.37 [0.25-0.55], and 0.44 [0.22-0.90], respectively). These two treatments also significantly decreased the proportion of patients receiving any allogeneic blood transfusion. By contrast, the use of desmopressin resulted in a small decrease in perioperative blood loss, but was not associated with a beneficial effect on other clinical outcomes. Aprotinin and lysine analogues did not increase the risk of perioperative myocardial infarction; however, desmopressin was associated with a 2.4-fold increase in the risk of this complication. Studies in patients undergoing complicated cardiac surgery showed similar results.

INTERPRETATION

Pharmacological strategies that decrease perioperative blood loss in cardiac surgery, in particular aprotinin and lysine analogues, also decrease mortality, the need for rethoracotomy, and the proportion of patients receiving a blood transfusion.

Hemostatic effects of aprotinin, tranexamic acid and epsilon-aminocaproic acid in primary cardiac surgery

BACKGROUND

The effects of epsilon-aminocaproic acid (EACA) and tranexamic acid (TA) on bleeding and allogeneic transfusions, and the cost of pharmacological and transfusional treatment were compared to aprotinin (AP).

METHODS

We randomized 210 patients subjected to elective cardiac surgery. Of these, 68 patients received EACA (a bolus of 5 g, an infusion of 2 g/h, and 2.5 g in the priming), 72 patients received TA (a bolus of 1 g, an infusion of 400 mg/h, and 500 mg in the priming), and 70 patients received AP (a bolus of 280 mg, an infusion of 70 mg/h, and 280 mg in the priming). Postoperative blood loss and homologous transfusions were collected and the cost of pharmacological treatment and homologous transfusions were calculated.

RESULTS

Bleeding but not allogeneic transfusions was significantly higher in the EACA group (467+/-234 versus TA, 311+/-231 versus AP, 283+/-233; p < 0.001). Costs of pharmacological and transfusional treatment were significantly lower in the TA group ($58.10+/-$105.10) versus the EACA group ($100.70+/-$158.60) versus the AP group ($432.60+/-$118.70) (p < 0.0001).

CONCLUSIONS

Compared to AP, TA has the same effects on bleeding and transfusions, but with a significant reduction of costs. Patients treated with EACA showed a significantly higher postoperative bleeding with an increased trend of transfusion requirement.

Alternatives to standard blood transfusion: availability and promise

Largely due to concerns over safety, a wide variety of alternatives to the conventional blood bank products of red cells, platelet concentrates, plasma and fractionated plasma products are under development. This review attempts to survey the alternative therapies that are being developed, whether they provide viable solutions and what impact they might have on transfusion practice.