Aprotinin significantly decreases bleeding and transfusion requirements in patients receiving aspirin and undergoing cardiac operations

Randomized controlled trials of aprotinin in cardiac surgery: could clinical equipoise have stopped the bleeding?

Background Aprotinin is a serine protease inhibitor used to limit perioperative bleeding and reduce the need for donated blood transfusions during cardiac surgery. Randomized controlled trials of aprotinin evaluating its effect on the outcome of perioperative transfusion have been published since 1987, and systematic reviews were conducted in 1992 and 1997.

Methods A systematic search was conducted for all RCTs of aprotinin that used placebo controls or were open-label with no active control treatment. Data collected included the primary outcome, objective of each study, whether a systematic review was cited or conducted as part of the background and/or rationale for the study and the number of previously published RCTs cited. Cumulative meta-analyses were performed.

Results Sixty-four randomized, controlled trials of aprotinin were found, conducted between 1987 and 2002, reporting an endpoint of perioperative transfusion. Median trial size was 64 subjects, with a range of 20 to 1784. A cumulative meta-analysis indicated that aprotinin greatly decreased the need for perioperative transfusion, stabilizing at an odds ratio of 0.25 (p, 10 2 6) by the 12th study, published in June of 1992. The upper limit of the confidence interval never exceeded 0.65 and results were similar in all subgroups. Citation of previous RCTs was extremely low, with a median of 20% of prior trials cited. Only 7 of 44 (15%) of subsequent reports referenced the largest trial (N 1/4 1784), which was 28 times larger than the median trial size.

Conclusions This study demonstrates that investigators evaluating aprotinin were not adequately citing previous research, resulting in a large number of RCTs being conducted to address efficacy questions that prior trials had already definitively answered. Institutional review boards and journals could reduce the number of redundant trials by requiring investigators to conduct adequate searches for prior evidence and conducting systematic reviews.

Aprotinin: No Justification for Current Use

Objective:

To review the pharmacology, pharmacokinetics, clinical efficacy, and safety of aprotinin.

Data Identification:

A literature search using Grateful Med from 1991 to 1994 and the search term “aprotinin” was performed.

Study Selection:

Open and controlled trials were reviewed.

Data Extraction:

Studies evaluating aprotinin for use in primary and repeat coronary artery bypass graft (CABG) surgery were evaluated and results of the effects of aprotinin on decreasing transfusion requirements as well as adverse effects were summarized.

Data Synthesis:

Many European studies have shown that aprotinin reduces blood loss and transfusion requirements during CABG. More recently, two studies in the US and one in Canada have been published that confirm the effects of aprotinin on blood loss, but raise questions concerning its safety. Combined data indicate that aprotinin is associated with an increased incidence of renal failure, and there are trends toward increases in myocardial infarction, graft occlusion, and mortality. There is no question that aprotinin reduces blood loss during CABG. How much it will save depends on surgical skill and the use of other blood conservation techniques. There are many theoretical benefits to patients from this reduction in blood loss. Whether the benefits of aprotinin administration exceed the risks associated with its use has not been adequately assessed, and further multicenter trials are currently in progress. Whether the cost of aprotinin is counterbalanced by a reduction in transfusion requirements will vary, depending on the cost and amount of blood products used at the specific institution, but this type of analysis does not account for the cost of adverse effects of aprotinin or transfusions, and no pharmacoeconomic evaluations have been published.

Conclusions:

Until studies can demonstrate a positive benefit/risk ratio in terms of patient outcome, aprotinin should not be added to the formulary or used in patients undergoing CABG.

Adverse Central Nervous System Outcomes After Cardiopulmonary Bypass: A Beneficial Effect of Aprotinin?

This review considers the evidence for potential central nervous system benefits associated with use of anti- protease therapy for patients undergoing procedures involving cardiopulmonary bypass. Unfortunately, few randomized, controlled clinical trials have assessed the lysine analogue class of antifibrinolytics (ie, ∈-amino caproic acid, tranexamic acid) compared with the num ber investigating the efficacy of the enzyme-inactivator class of antifibrinolytic typified by the nonspecific serine protease inhibitors aprotinin and nafamostat.

Use of Aprotinin in the Control of Bleeding During Cardiopulmonary Bypass Surgery: Current Status

Excessive bleeding is one of the major complica tions of cardiac surgery with cardiopulmonary bypass (CPB). This complication is related to the operation and the defects in hemostasis induced by extracorporeal circulation. The system atic effects of CPB are called whole body inflammatory reac tion. Heparin, platelet dysfunctions, and fibrinolysis are the major causes of bleeding problems associated with CPB. Dif ferent pharmacological approaches have been used to reduce bleeding and the need for blood transfusions in patients under going cardiac surgery. The most effective is aprotinin, a serum protease inhibitor that is an antifibrinolytic with a platelet- preserving action. It inhibits the activation of the intrinsic co agulation system. Aprotinin therapy effectively reduces blood loss and donor blood requirements. According to most reports, it does not increase the risk of acute myocardial infarction, renal dysfunction, and mortality.

The relationship between low intraoperative hematocrit levels during cardiopulmonary bypass and postoperative neurological events

OBJECTIVE

The objective of our study is to analyze whether low intraoperative hematocrit levels have an effect upon postoperative neurological events.

METHODS

Our study included 140 patients who underwent isolated coronary bypass under cardiopulmonary bypass between 2009 and 2012. The main group of the study was 70 patients with intraoperative hematocrit levels lower than 22%. These patients' 30-day postoperative neurological (particularly stroke) follow up was registered as the main data of the study. Another group of 70 patients possessing the same demographic features who underwent open heart surgery with hematocrit levels remaining above 22% were registered as the control group for perioperative neurological data.

RESULTS

The average age of the patients with hematocrit levels below and above 22% was 56.8 ± 5.8 years and 54.1 ± 7.3 years, respectively. The mean follow-up period of the patients was 37.2 ± 8.6 days. None of the patients had any neurological postoperative sequalae. No mortalities occurred. One patient who had mild paresthesia and motor weakness of the left hand had no pathological finding on computed tomography and was diagnosed with peripheral neuropathy due to intraoperative sternal retraction.

CONCLUSION

Because our study revealed no cerebrovascular events, coronary bypass surgery under cardiopulmonary bypass may be safely conducted even in patients with hematocrit levels lower than 22%.

Clopidogrel dilemma for orthopaedic surgeons

BACKGROUND

Patients medicated with clopidogrel who require orthopaedic surgery present a particular challenge. Whether in an emergency or elective situation the orthopaedic surgeon must balance the risks of ceasing clopidogrel versus the risk of increased bleeding that dual antiplatelet therapy generates.

METHOD

This paper reviews the current published evidence regarding the risks of continuing clopidogrel, the risks of discontinuing clopidogrel and associated considerations such as venous thromboprophylaxis.

RESULTS

Little good quality evidence exists in regard to perioperative clopidogrel for orthopaedic surgery. Available evidence across non-cardiac and cardiac surgery were assessed and presented in regards to current practices, blood loss for orthopaedic operations, risks when continuing clopidogrel, risks of stopping clopidogrel and also the consideration of venous thromboembolism.

CONCLUSIONS

The patients at greatest risk, when discontinuing clopidogrel therapy, are those with drug eluting stents who may be at risk of stent thrombosis. Where possible, efforts should be made to continue clopidogrel therapy through the perioperative period, taking precautions to minimize bleeding. If the risk of bleeding is too high, antiplatelet therapy must be reinstated as soon as considered reasonable after surgery. In addition, patients on clopidogrel who sustain a fall or other general trauma need to be carefully assessed because of the possibility of occult bleeding, such as into the retroperitoneal space. Until more definitive evidence becomes available, this review aims to provide a guide for the orthopaedic surgeon in dealing with the difficult dilemma of the patient on clopidogrel therapy, recommending that orthopaedic surgeons take a team approach to assess the individual risks for all patients and consider continuation of clopidogrel therapy perioperatively where possible.

Anti-fibrinolytic use for minimising perioperative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood have led to the development of a range of interventions to minimise blood loss during major surgery. Anti-fibrinolytic drugs are widely used, particularly in cardiac surgery, and previous reviews have found them to be effective in reducing blood loss, the need for transfusion, and the need for re-operation due to continued or recurrent bleeding. In the last few years questions have been raised regarding the comparative performance of the drugs. The safety of the most popular agent, aprotinin, has been challenged, and it was withdrawn from world markets in May 2008 because of concerns that it increased the risk of cardiovascular complications and death.

OBJECTIVES

To assess the comparative effects of the anti-fibrinolytic drugs aprotinin, tranexamic acid (TXA), and epsilon aminocaproic acid (EACA) on blood loss during surgery, the need for red blood cell (RBC) transfusion, and adverse events, particularly vascular occlusion, renal dysfunction, and death.

SEARCH STRATEGY

We searched: the Cochrane Injuries Group's Specialised Register (July 2010), Cochrane Central Register of Controlled Trials (The Cochrane Library 2010, Issue 3), MEDLINE (Ovid SP) 1950 to July 2010, EMBASE (Ovid SP) 1980 to July 2010. References in identified trials and review articles were checked and trial authors were contacted to identify any additional studies. The searches were last updated in July 2010.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of anti-fibrinolytic drugs in adults scheduled for non-urgent surgery. Eligible trials compared anti-fibrinolytic drugs with placebo (or no treatment), or with each other.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data.

MAIN RESULTS

This review summarises data from 252 RCTs that recruited over 25,000 participants. Data from the head-to-head trials suggest an advantage of aprotinin over the lysine analogues TXA and EACA in terms of reducing perioperative blood loss, but the differences were small. Compared to control, aprotinin reduced the probability of requiring RBC transfusion by a relative 34% (relative risk [RR] 0.66, 95% confidence interval [CI] 0.60 to 0.72). The RR for RBC transfusion with TXA was 0.61 (95% CI 0.53 to 0.70) and was 0.81 (95% CI 0.67 to 0.99) with EACA. When the pooled estimates from the head-to-head trials of the two lysine analogues were combined and compared to aprotinin alone, aprotinin appeared more effective in reducing the need for RBC transfusion (RR 0.90; 95% CI 0.81 to 0.99).Aprotinin reduced the need for re-operation due to bleeding by a relative 54% (RR 0.46, 95% CI 0.34 to 0.62). This translates into an absolute risk reduction of 2% and a number needed-to-treat (NNT) of 50 (95% CI 33 to 100). A similar trend was seen with EACA (RR 0.32, 95% CI 0.11 to 0.99) but not TXA (RR 0.80, 95% CI 0.55 to 1.17). The blood transfusion data were heterogeneous and funnel plots indicate that trials of aprotinin and the lysine analogues may be subject to publication bias.When compared with no treatment aprotinin did not increase the risk of myocardial infarction (RR 0.87, 95% CI 0.69 to 1.11), stroke (RR 0.82, 95% CI 0.44 to 1.52), renal dysfunction (RR 1.10, 95% CI 0.79 to 1.54) or overall mortality (RR 0.81, 95% CI 0.63 to 1.06). Similar trends were seen with the lysine analogues, but data were sparse. These data conflict with the results of recently published non-randomised studies, which found increased risk of cardiovascular complications and death with aprotinin. There are concerns about the adequacy of reporting of uncommon events in the small clinical trials included in this review.When aprotinin was compared directly with either, or both, of the two lysine analogues it resulted in a significant increase in the risk of death (RR 1.39, 95% CI 1.02, 1.89), and a non-significant increase in the risk of myocardial infarction (RR 1.11 95% CI 0.82, 1.50). Most of the data contributing to this added risk came from a single study - the BART trial (2008).

AUTHORS' CONCLUSIONS

Anti-fibrinolytic drugs provide worthwhile reductions in blood loss and the receipt of allogeneic red cell transfusion. Aprotinin appears to be slightly more effective than the lysine analogues in reducing blood loss and the receipt of blood transfusion. However, head to head comparisons show a lower risk of death with lysine analogues when compared with aprotinin. The lysine analogues are effective in reducing blood loss during and after surgery, and appear to be free of serious adverse effects.

Management of bleeding and of invasive procedures in patients with platelet disorders and/or thrombocytopenia: Guidelines of the Italian Society for Haemostasis and Thrombosis (SISET)

The optimal management of bleeding or its prophylaxis in patients with disorders of platelet count or function is controversial. The bleeding diathesis of these patients is usually mild to moderate: therefore, transfusion of platelet concentrates may be inappropriate, as potential adverse effects might outweigh its benefit. The availability of several anti-hemorrhagic drugs further compounds this problem, mainly because the efficacy/suitability of the various treatment options in different clinical manifestations is not well defined. In these guidelines, promoted by the Italian Society for Studies on Haemostasis and Thrombosis (Società Italiana per lo Studio dell'Emostasi e della Trombosi [SISET]), we aim at offering the best available evidence to help the physicians involved in the management of patients with disorders of platelet count or function. Literature review and appraisal of available evidence are discussed for different clinical settings and for different available treatments, including platelet concentrates (PC), recombinant activated factor VII, desmopressin, antifibrinolytics, aprotinin and local hemostatic agents.

Living without aprotinin: the results of a 5-year blood saving program in cardiac surgery

BACKGROUND

After 20 years of regular use in cardiac surgery patients, aprotinin has recently been withdrawn from the market due to many concerns about its safety. For a number of reasons aprotinin has not been available in Italy since 1998. The present study presents an aprotinin-free treatment protocol applied at our institution during the last 5 years, and aims to verify the results of this protocol in terms of allogeneic blood product transfusions, postoperative blood loss and surgical re-exploration rate.

METHODS

Retrospective study on 7988 consecutive patients who underwent cardiac surgery during the years 2003-2007. All the patients received specific hemostasis/coagulation management based on (a) routine use of tranexamic acid, (b) heparin dose-response monitoring, thromboelastography, platelet (PLT) function analysis in a select population of patients, and (c) use of fresh frozen plasma (FFP), PLTs, and desmopressin according to the hemostasis/coagulation profile. Data retrieved from the institutional database were quantity of packed red cells (PRCs), FFP, PLT transfusion rate, blood loss in the first 12 postoperative hours, and surgical re-exploration rate.

RESULTS

PRCs were transfused in 40.4% of patients (with higher rates for selected high-risk subpopulations), FFP in 12.9% and PLTs in 2.6%. Surgical re-exploration rate was 3.7%. With respect to historical controls, a significant reduction of PRCs and FFP transfusions was obtained using closed circuits, point of care coagulation tests, and combination of the two.

CONCLUSION

This aprotinin-free blood saving program is an effective strategy for allogeneic blood products transfusion containment.

A possible association between aprotinin and improved survival after radical surgery for mesothelioma

BACKGROUND

Aprotinin has been used to decrease blood loss with complicated cardiac surgery but has not been investigated in extrapleural pneumonectomy, an operation that does not use cardiopulmonary bypass. In this prospective, randomized, placebo-controlled, double-blind trial, the authors investigated whether aprotinin decreased blood loss in patients who underwent this operation.

METHODS

After appropriate statistical design and institutional review board approval, eligible patients who were scheduled for extrapleural pneumonectomy were randomized to receive either aprotinin or placebo during the operation. Blood loss and survival data were obtained from electronic medical records and surgical databases.

RESULTS

Of 20 patients who were enrolled, 16 patients met criteria for blood loss analysis. Four patients were excluded from the blood loss analysis: Three patients were inoperable because of tumor spread and underwent limited surgery, and 1 patient died intraoperatively because of acute, massive hemorrhage. The mean blood loss was 769 mL with aprotinin versus 1832 mL with placebo (P = .05; Wilcoxon test). All 20 patients were included in survival analyses. All 9 patients who received placebo died. In contrast, 7 of 11 patients who received aprotinin remained alive at the time of the current report. Kaplan-Meier survival curves differed significantly between the 2 groups (P = .0004). A Bayesian multivariate survival analysis of 18 patients who had complete data available on 8 prognostic variables indicated a posterior probability of .99 that aprotinin was beneficial.

CONCLUSIONS

Aprotinin decreased blood loss. After accounting for covariate effects, there was a significant comparative benefit with aprotinin in postoperative survival. This finding was unexpected and could not be considered conclusive because of the small size of the current study. A confirmatory study may be warranted.

Effect of clopidogrel on bleeding and transfusions after off-pump coronary artery bypass graft surgery: impact of discontinuation prior to surgery

OBJECTIVE

The use of antiplatelet drugs to treat acute myocardial infarction, unstable angina, acute coronary syndrome and secondary prevention following percutaneous coronary interventions is well accepted. However, it constitutes a serious risk of bleeding for patients undergoing coronary artery bypass grafting surgery (CABG). We evaluated the effect of aspirin and clopidogrel (CPDG), both irreversible platelet aggregation inhibitors, on operative bleeding and determined the optimal timing for their discontinuation before surgery.

METHOD

Between July 2001 and December 2004, we reviewed our experience with 453 patients undergoing off-pump CABG surgery (OPCAB) who received CPDG (n=101) or not (n=352) preoperatively, and compared the intraoperative and postoperative bleeding to determine risks factors associated with blood or platelet transfusions.

RESULTS

Clopidogrel in OPCAB surgery is associated with higher intraoperative (702.24 ml vs 554.13 ml, p=0.03) and postoperative bleeding (864.93 ml vs 603.75 ml, p=0.03). The mean operative blood loss is higher in patients still on CPDG at the time of surgery compared to patients off CPDG at least 72 h before surgery (802 ml vs 554.13 ml, p<0.0001). Blood loss in the later subgroup of patients is comparable to the control group without CPDG (p=NS). Clopidogrel is associated with more platelet transfusions (OR=11.79, [1.48; 93.86]).

CONCLUSION

Blood loss is higher in OPCAB patients receiving clopidogrel before surgery. However, discontinuation of clopidogrel three days (72 h) prior to the operation demonstrated a similar blood loss pattern compared to a control group. Clopidogrel is associated with more platelets, but not red blood cell transfusions following OPCAB surgery.

Novel antithrombotic agents and the risk of bleeding

Many coronary patients on antiplatelet (PLT) drugs require coronary artery bypass grafting surgery under conditions that may not allow sufficient time for or warrant discontinuation of anti-PLT treatment. Recent clinical data show that intraoperative aprotinin significantly reduces postoperative bleeding and transfusion requirements in this patient population. If surgical bleeding persists, the administration of Factor VIIa should be considered.

Correction of the Bleeding Time With Lyophilized Platelet Infusions in Dogs on Cardiopulmonary Bypass

Lyophilized canine platelets were infused in a single large bolus dose into splenectomized dogs after 2 hours' perfusion on cardiopulmonary bypass to test their possible efficacy in restoring hemostasis after compromise of platelet function. The vessel bleeding time (VBT) was monitored by venipuncture of the exposed jugular vein. During cardiopulmonary bypass, platelet counts fell quickly and the VBTs became prolonged over baseline. Infusion of lyophilized platelets reconstituted in normal saline occurred just before or immediately after weaning from the cardiopulmonary bypass pump. The results showed consistent and persistent lowering of the VBTs by the infused lyophilized platelets. Controls showed continuously prolonged VBTs. The weighted average VBT in infused subjects was significantly lower than the average in controls: 3 minutes 10 seconds versus 6 minutes 59 seconds, respectively ( t test, P = .01). These results in this setting indicate the possible effectiveness of similar human lyophilized platelet preparations in reducing postoperative bleeding in open heart surgery.

Anti-fibrinolytic use for minimising perioperative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood have led to the development of a range of interventions to minimise blood loss during major surgery. Anti-fibrinolytic drugs are widely used, particularly in cardiac surgery and previous reviews have found them to be effective in reducing blood loss and the need for transfusion. Recently, questions have been raised regarding the comparative performance of the drugs and the safety of the most popular agent, aprotinin.

OBJECTIVES

To assess the comparative effects of the anti-fibrinolytic drugs aprotinin, tranexamic acid (TXA), and epsilon aminocaproic acid (EACA) on blood loss during surgery, the need for red blood (RBC) transfusion, and adverse events, particularly vascular occlusion, renal dysfunction, and death.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE, EMBASE, and the internet. References in identified trials and review articles were checked and trial authors were contacted to identify any additional studies. The searches were last updated in July 2006.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of anti-fibrinolytic drugs in adults scheduled for non-urgent surgery. Eligible trials compared anti-fibrinolytic drugs with placebo (or no treatment), or with each other.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data.

MAIN RESULTS

This review summarises data from 211 RCTs that recruited 20,781 participants. Data from placebo/inactive controlled trials, and from head-to-head trials suggest an advantage of aprotinin over the lysine analogues TXA and EACA in terms of operative blood loss, but the differences were small. Aprotinin reduced the probability of requiring RBC transfusion by a relative 34% (relative risk [RR] 0.66, 95% confidence interval [CI] 0.61 to 0.71). The RR for RBC transfusion with TXA was 0.61 (95% CI 0.54 to 0.69) and it was 0.75 (95% CI 0.58 to 0.96) with EACA. When the pooled estimates from the head-to-head trials of the two lysine analogues were combined and compared to aprotinin alone, aprotinin appeared superior in reducing the need for RBC transfusion: RR 0.83 (95% CI 0.69 to 0.99). Aprotinin reduced the need for re-operation due to bleeding: RR 0.48 (95% CI 0.35 to 0.68). This translates into an absolute risk reduction of just under 3% and a number needed-to-treat (NNT) of 37 (95% CI 27 to 56). Similar trends were seen with TXA and EACA, but the data were sparse and the differences failed to reach statistical significance. The blood transfusion data were heterogeneous and funnel plots indicate that trials of aprotinin and the lysine analogues may be subject to publication bias. Evidence of publication bias was not observed in trials reporting re-operation rates. Adjustment for these effects reduced the magnitude of estimated benefits but did not negate treatment effects. However, the apparent advantage of aprotinin over the lysine analogues was small and may be explained by publication bias and non-equivalent drug doses. Aprotinin did not increase the risk of myocardial infarction (RR 0.92, 95% CI 0.72 to 1.18), stroke (RR 0.76, 95% CI 0.35 to 1.64) renal dysfunction (RR 1.16, 95% CI 0.79 to 1.70) or overall mortality (RR 0.90, 95% CI 0.67 to 1.20). The analyses of myocardial infarction and death included data from the majority of subjects recruited into the clinical trials of aprotinin. However, under-reporting of renal events could explain the lack of effect seen with aprotinin. Similar trends were seen with the lysine analogues but data were sparse. These results conflict with the results of recently published non-randomised studies.

AUTHORS' CONCLUSIONS

Anti-fibrinolytic drugs provide worthwhile reductions in blood loss and the need for allogeneic red cell transfusion. Based on the results of randomised trials their efficacy does not appear to be offset by serious adverse effects. In most circumstances the lysine analogues are probably as effective as aprotinin and are cheaper; the evidence is stronger for tranexamic acid than for aminocaproic acid. In high risk cardiac surgery, where there is a substantial probability of serious blood loss, aprotinin may be preferred over tranexamic acid. Aprotinin does not appear to be associated with an increased risk of vascular occlusion and death, but the data do not exclude an increased risk of renal failure. There is no need for further placebo-controlled trials of aprotinin or lysine analogues in cardiac surgery. The principal need is for large comparative trials to assess the relative efficacy, safety and cost-effectiveness of anti-fibrinolytic drugs in different surgical procedures.

Evaluation of aprotinin and tranexamic acid in different in vitro and in vivo models of fibrinolysis, coagulation and thrombus formation

BACKGROUND

The serine protease inhibitor aprotinin and plasminogen inhibitor tranexamic acid are used in coronary artery bypass graft (CABG) surgery to reduce bleeding. Clinicians may consider these agents as readily substitutable regarding their pharmacological profiles.

OBJECTIVE

These agents were evaluated in assays of hemostasis to elucidate their underlying mechanism(s) of action.

METHODS

In human plasma, effects on both clot fibrinolysis and coagulation were spectrophotometrically quantified in vitro. Rat-tail bleeding and arteriovenous shunt thrombus formation models were conducted in vivo.

RESULTS

Fibrinolysis was inhibited by aprotinin (IC(50), 0.16 +/- 0.02 micromol L(-1)) and tranexamic acid (IC(50), 24.1 +/-1.1 micromol L(-1)). In vivo, aprotinin dose-dependently reduced rat-tail bleeding time (minimal effective dose, 3 mg kg(-1) bolus plus 6 mg kg(-1 )h(-1) infusion); tranexamic acid reduced bleeding time (minimal effective dose, 100 mg kg(-1) h(-1)). In vitro, coagulation time was doubled by aprotinin at 3.2 +/- 0.2 micromol L(-1), while tranexamic acid showed no effect at concentrations up to 3 mmol L(-1). Aprotinin inhibited thrombus formation in vivo in a dose-dependent manner (minimal effective dose, 3 mg kg(-1) bolus plus 6 mg kg(-1) h(-1) infusion). Conversely, tranexamic acid dose-dependently increased thrombus formation and thrombus weight (minimal effective dose, 100 mg kg(-1 )h(-1) infusion).

CONCLUSIONS

These data show that aprotinin and tranexamic acid have differential effects on hemostasis and are not necessarily substitutable with respect to mechanism of action. Although both agents have been shown to reduce bleeding in patients undergoing CABG, their divergent effects on thrombus formation observed in vitro and in vivo should be critically evaluated clinically.

Effect of recombinant aprotinin on postoperative blood loss and coronary vascular function in a canine model of cardiopulmonary bypass

OBJECTIVE

Aprotinin is a widely used serine protease inhibitor during cardiopulmonary bypass to reduce blood loss and preserve platelet function. However, the bovine-derived aprotinin can induce hypersensitivity reaction with fatal complications. Furthermore, vascular effects of aprotinin are not completely elucidated. The current study is designed to investigate the effects of recently developed recombinant aprotinin on blood loss and coronary vascular function in a clinically relevant canine model of cardiopulmonary bypass without aortic cross-clamping and cardioplegia.

METHODS

Twenty-four dogs underwent cardiopulmonary bypass without aortic cross-clamping and cardioplegia. Dogs were divided into three groups in a blinded fashion: control animals (n=8) received placebo, aprotinin treatment groups received bovine (n=8) or recombinant aprotinin (n=8) according to the Hammersmith method. The doses of bovine and recombinant aprotinin were the same. Coagulation parameters and blood loss were measured regularly at different time points. Endothelium-dependent and -independent vasorelaxation were investigated in isolated left anterior descendent coronary arterial rings by using acetylcholine and bradykinin or sodium nitroprusside and adenosine, respectively.

RESULTS

Postoperative blood loss was significantly reduced in the aprotinin-treated groups in comparison to control and there was no significant difference between the two aprotinin-treated groups. Endothelium-dependent relaxation of coronary arteries to acetylcholine and bradykinin was unaffected in the aprotinin treatment groups. Both types of aprotinin significantly increased vasorelaxation to adenosine when compared with controls, but did not affect that to sodium nitroprusside.

CONCLUSIONS

The effectiveness of recombinant aprotinin on blood loss was equivalent to bovine-derived aprotinin. Neither types of aprotinin impaired endothelium-dependent relaxation in a canine model of cardiopulmonary bypass.

Aprotinin Use in Cardiac Surgery Patients at Low Risk for Requiring Blood Transfusion

STUDY OBJECTIVES

To determine if aprotinin is safe and effective in patients at low risk for requiring blood transfusion after cardiac surgery by evaluating whether there is any significant difference in blood product use or other significant clinical outcomes between patients who received aprotinin versus those who did not.

DESIGN

Retrospective review.

SETTING

Inpatient community nonteaching hospital.

PATIENTS

Three hundred thirty-five patients who underwent primary cardiac surgery involving cardiopulmonary bypass between November 1, 2003, and December 31, 2005, and were considered at low risk for requiring postoperative blood transfusion; 162 patients received aprotinin and 173 patients received aminocaproic acid (control).

MEASUREMENTS AND MAIN RESULTS

Comparison of patients in the aprotinin group versus those in the aminocaproic acid group revealed no difference in total donor exposures to blood products (1.86 vs 1.16 units/patient, p=0.07), total packed red blood cells (PRBCs) received (1.25 vs 0.86 units/patient, p=0.09), postoperative donor exposures to blood products (0.91 vs 0.48 unit/patient, p=0.13), or postoperative PRBCs received (0.61 vs 0.40 unit/patient, p=0.23). No difference was noted in any other clinical outcome in the aprotinin group versus the aminocaproic acid group, including postoperative azotemia (13.0% vs 10.4%, p=0.46), new onset of atrial fibrillation (14.8% vs 15.0%, p=0.95), myocardial infarction, stroke, or death. Mean +/- SD total hospital length of stay was similar in the aprotinin group versus the aminocaproic acid group (8.1 +/- 3.8 vs 7.4 +/- 2.8 days, p=0.08), but length of stay from surgery to discharge was longer in the aprotinin group than in the aminocaproic acid group (5.9 +/- 0.17 vs 5.4 +/- 0.12 days, p=0.032).

CONCLUSION

Although aprotinin appeared to be safe in this low-risk patient population, it was not more effective than aminocaproic acid in reducing blood product use after cardiac surgery. More robust evidence is needed from a controlled randomized trial to demonstrate the safety, efficacy, and pharmacoeconomic benefit of aprotinin.

Meta-analysis comparing the effectiveness and adverse outcomes of antifibrinolytic agents in cardiac surgery

BACKGROUND

Since the 1980s, antifibrinolytic therapies have assisted surgical teams in reducing the amount of blood loss. To date, however, serious questions remain regarding the safety and effectiveness of these agents.

METHODS AND RESULTS

We conducted a meta-analysis to compare aprotinin, epsilon-aminocaproic acid, and tranexamic acid with placebo and head to head on 8 clinical outcomes from 138 trials. Published randomized controlled trial data were collected from OVID/PubMed. Outcomes included total blood loss, transfusion of packed red blood cells, reexploration, mortality, stroke, myocardial infarction, dialysis-dependent renal failure, and renal dysfunction (0.5-mg/dL increase in creatinine from baseline). All agents were effective in significantly reducing blood loss by 226 to 348 mL and the proportion of patients transfused with packed red blood cells over placebo. Only high-dose aprotinin reduced the rate of reexploration (relative risk, 0.49; 95% CI, 0.33 to 0.73). There were no significant risks or benefits for any agent for mortality, stroke, myocardial infarction, or renal failure. However, high-dose aprotinin significantly increased the risk of renal dysfunction (relative risk, 1.47; 95% CI, 1.12 to 1.94), 12.9% versus 8.4%. Compared head to head, high-dose aprotinin demonstrated significant reduction in total blood loss over epsilon-aminocaproic acid (-184 mL; 95% CI, -256 to -112) and tranexamic acid (-195 mL; 95% CI, -286 to -105). There were no significant differences among any agent when compared head to head on other outcomes.

CONCLUSIONS

All antifibrinolytic agents were effective in reducing blood loss and transfusion. There were no significant risks or benefits for mortality, stroke, myocardial infarction, or renal failure. However, high-dose aprotinin was associated with a statistically significant increased risk of renal dysfunction.

Recombinant Factor VIIa Reduces Bleeding Risk in Patients on Platelet Aggregation Inhibitors Immediately prior to Renal Transplantation – A Retrospective Analysis

BACKGROUND

Transplant surgery often requires an effective preoperative treatment which allows to reduce the risk of bleeding caused by platelet aggregation inhibitors without major delay. The use of recombinant activated coagulation factor VIIa (rFVIIa) may be a future treatment option in such patients.

METHOD

Five patients with end-stage renal disease on treatment with platelet aggregation inhibitors (ASA, Plavix, Aggrenox), who were scheduled for renal transplantation and received a preoperative bolus of recombinant factor VIIa (rFVIIa, NovoSeven) in a dose of 3 kIU/kg (60 microg/kg), were retrospectively analyzed. Parameters of plasmatic coagulation as well as bleeding time were determined before as well as after the administration of rFVIIa.

RESULTS

The initial median bleeding time was 7.3 min (range 6.2-14.6); after administration of rFVIIa it fell to 2.8 min (range 1.8-3.2). All patients had a good intraoperative hemostasis. None of the patients developed a hematoma requiring surgical treatment. The graft of all patients was homogeneously and well perfused, with a sufficient postoperative diuresis.

CONCLUSION

The administration of rFVIIa prior to renal transplantation in patients on treatment with platelet aggregation inhibitors was effective and without major complications. Further studies should be performed in order to confirm our observations.

Effects of minimal dose aprotinin on blood loss and fibrinolytic system-complement activation in coronary artery bypass grafting surgery

BACKGROUND

To determine whether 500,000 KIU aprotinin is effective to reduce blood loss in coronary artery bypass grafting (CABG) and to evaluate the effects of this regimen on hematologic parameters.

METHODS

Forty-four patients scheduled for primary CABG were randomly assigned to the aprotinin (n = 24) or control group (n = 20). In aprotinin group, aprotinin was administered in two equal doses (before skin incision and added to the pump prime). Ventilation time, intensive care unit stay, mediastinal tube drainage, hospitalization, transfusion requirements, and postoperative morbidities and mortality were noted. Hematologic markers of fibrinolytic activity and complement activation were also measured pre- and postoperatively.

RESULTS

Although less mediastinal drainage occurred in aprotinin group, the difference was not statistically significant. Other postoperative variables like transfusion requirements, morbidities, and mortality were also found to be similar between groups. Among hematologic parameters, only postoperative levels of alpha2-antiplasmin and plasminogen activator inhibitor-1 were significantly higher in aprotinin group.

CONCLUSIONS

Although plasmin inhibitors begin to rise at this very low aprotinin dosage, it is not advisable to use this aprotinin regimen in CABG patients.

Low-dose aspirin before intracranial surgery--results of a survey among neurosurgeons in Germany

BACKGROUND

Increasing numbers of patients presenting for intracranial surgery are receiving concurrent medication with low-dose aspirin, leading to dysfunctional circulating platelets, which might increase the peri-operative risk of bleeding.

OBJECTIVE

To survey the opinions and working practices of neurosurgical facilities in Germany regarding patients who present with low-dose aspirin medication before elective intracranial surgery. Methods. Questionnaires were sent to 210 neurosurgical facilities asking five main questions: (1) the adherence of any policy of stopping aspirin pre-operatively, (2) the personal risk assessment for patients with brain surgery under low-dose aspirin medication, (3) the preferred method of treatment for excessive bleeding in this context, (4) personal knowledge of haemorrhagic complications in this group of patients, and (5) the characteristics of the neurosurgical units concerned.

RESULTS

There were 138 (65.7%) valid responses. Of the respondents, 111 (80.4%) had a departmental policy for the discontinuation of pre-operative aspirin treatment. The mean time for discontinuation of aspirin pre-operatively was 7.3 days (range: 0-21 days). 107 respondents (77.5%) considered that patients taking low-dose aspirin were at increased risk for excessive peri-operative haemorrhage, and 80 (58%) reported having personal experience of such problems. Ninety-seven respondents (70.3%) would use special medical therapy, preferably desmopressin, if haemorrhagic complications developed intra-operatively. The mean amount of intracranial operations per year in each neurosurgical facility was 494 (range: 50-1700).

CONCLUSIONS

The majority of neurosurgical facilities in Germany have distinct departmental policies concerning the discontinuation of low-dose aspirin pre-operatively, with an average of 7.3 days. Three-quarter of the respondents felt that aspirin was a risk factor for haemorrhagic complications associated with intracranial procedures, and more than half of the interviewees reported having personal experience of such problems. Various medicamentous methods of counteracting aspirin-induced platelet dysfunction and excessive bleeding in this context are discussed and evaluated.

Low-dose aspirin before spinal surgery: results of a survey among neurosurgeons in Germany

The main problem faced by the increasing numbers of patients presenting for spinal surgery are receiving concurrent medication with low-dose aspirin, leading to dysfunctional circulating platelets. The contribution of low-dose aspirin to increased peri-operative risk of bleeding and blood loss is a contentious issue with conflicting published results from different surgical groups. Data from neurosurgical spine patients is sparse, but aspirin has been identified as an important risk factor in the development of post-operative hematoma following intracranial surgery. We surveyed the opinions and working practices of the neurosurgical facilities performing spinal operations in Germany regarding patients who present for elective spinal surgery. Identical questionnaires were sent to 210 neurosurgical facilities and proffered five main questions: (1) the adherence of any policy of stopping aspirin pre-operatively, (2) the personal risk assessment for patients with spinal surgery under low-dose aspirin medication, (3) the preferred method of treatment for excessive bleeding in this context, (4) personal knowledge of hemorrhagic complications in this group of patients, and (5) the characteristics of the neurosurgical units concerned. There were 145 (69.1%) responses of which 142 (67.6%) were valid. Of the respondents, 114 (80.3%) had a (written) departmental policy for the discontinuation of pre-operative aspirin treatment, 28 (19.7%) were unaware of such a policy. The mean time suggested for discontinuation of aspirin pre-operatively was 6.9 days (range: 0-21 days), with seven respondents who perform the operations despite the ongoing aspirin medication. Ninety-four respondents (66.2%) considered that patients taking low-dose aspirin were at increased risk for excessive peri-operative hemorrhage or were indetermined (8.6%), and 73 (51.4%) reported having personal experience of such problems. Ninety-two respondents (65.5%) would use special medical therapy, preferably Desmopressin alone or in combination with other blood products or prohemostatic agents (46.1%), if hemorrhagic complications developed intra- or post-operatively. The average number of spinal operations per year in each service was 607.9 (range: 40-1,500). Despite the existence of distinct departmental policies concerning the discontinuation of low-dose aspirin pre-operatively in the majority of neurosurgical facilities performing spinal operations, there is a wide range of the moment of this interruption with an average of 7 days. Two-thirds of the respondents felt that aspirin was a risk factor for hemorrhagic complications associated with spinal procedures, and more than half of the interviewees reported having personal experience of such problems. Finally, various medicamentous methods of counteracting aspirin-induced platelet dysfunction and excessive bleeding in this context are elicited, discussed and evaluated.

New developments in pediatric cardiac anesthesia

As the practice of pediatric cardiac anesthesia continues to grow, anesthesiologists now routinely care for patients ranging in size from less than 2 kg to more than 100 kg. New clinical and laboratory research has enhanced our understanding of the effects of anesthetic drugs on the pediatric myocardium, and improvements in survival statistics for even the smallest and sickest infants have shifted the emphasis to evaluation of quality of life and neurological outcome in pediatric cardiac patients. The use of circulatory support in infants and children, both for rapid resuscitation and for more chronic indications such as bridge to transplantation, also continues to evolve, with the recent introduction of pulsatile and axial pumps for pediatric use. This article reviews anesthetic agents, bleeding and coagulation, neurological monitoring, and mechanical circulatory support in the treatment of infants and children.

Aprotinin Reduces Bleeding and Blood Product Use in Patients Treated With Clopidogrel Before Coronary Artery Bypass Grafting

BACKGROUND

An increased proportion of patients undergoing urgent coronary artery bypass graft surgery (CABG) is being treated with clopidogrel, an irreversible platelet inhibitor. Clopidogrel in combination with aspirin is known to augment bleeding, transfusion requirements, and reoperation rates after CABG. Aprotinin, a protease inhibitor, is approved for use in cardiac surgery to reduce bleeding. The aim of this study was to investigate whether or not intraoperative use of aprotinin decreases bleeding and number of transfusions after CABG in patients treated with clopidogrel less than 5 days before surgery.

METHODS

We retrospectively reviewed the medical records of all consecutive patients, with preoperative clopidogrel exposure less than 5 days before surgery, who underwent urgent CABG at our institution during 1 year (n = 33). Eighteen patients received a full-dose aprotinin regime intraoperatively whereas 15 patients not receiving aprotinin served as a control group.

RESULTS

The two groups were comparable with respect to baseline characteristics and operative data. Mean postoperative bleeding was 710 mL (95% confidence interval [CI]: 560 to 860) in the aprotinin group versus 1,210 mL (95% CI: 860 to 1550) in the control group (p = 0.004). The aprotinin group received fewer transfusions of packed red blood cells (0.9 U, 95% CI: 0.1 to 1.7, versus 2.7 U, 95% CI: 1.4 to 4.1; p = 0.01), platelets (0.1 U, 95% CI: 0 to 0.3, versus 0.6 U, 0.2 to 0.9; p = 0.02), and fewer blood product units (1.1 U, 95% CI: 0.1 to 2.0, versus 3.7 U, 95% CI: 2.1 to 5.4; p = 0.002). There were 3 reoperations for bleeding, all in the control group (p = 0.05).

CONCLUSIONS

Aprotinin reduces bleeding, transfusion requirements of packed red blood cells, platelets, and total blood units in patients on clopidogrel undergoing urgent CABG.

Aprotinin Decreases Postoperative Bleeding and Number of Transfusions in Patients on Clopidogrel Undergoing Coronary Artery Bypass Graft Surgery

Background— Clopidogrel, an irreversible platelet inhibitor, is used to treat patients with unstable angina. These patients often present for coronary artery bypass graft surgery (CABG) and are at increased risk for perioperative bleeding. The current investigation evaluates the impact of aprotinin on bleeding and transfusion requirements in clopidogrel-treated patients undergoing CABG.

Methods and Results— Seventy-five consecutive patients with unstable angina, administered clopidogrel <5 days before CABG, were randomized. Using a double-blind design, patients received full-dose aprotinin (n =37) or saline (n =38). Elapsed times between the last dose of clopidogrel and start of the operation were similar between the 2 groups [aprotinin, 58±28 hour (mean± SD); control, 54±27 hour; P =0.86], as were age (aprotinin, 66.4±10 years; control, 68.3±10 years; P =0.51), number of distal anastomoses (aprotinin, 3.6±1.0; control, 3.7±1.0; P =0.79), operative times (aprotinin, 192±48 minutes; control, 200±53 minutes; P =0.55), and lowest intraoperative hemoglobin level (aprotinin, 87±14 g/L; control, 88±14 g/L; P =0.60). Postoperative bleeding was 760±350 mL in aprotinin-treated patients versus 1200±570 mL ( P <0.001) in control. During the hospital stay, patients in the aprotinin group received 1.2±1.5 and 0.1±0.4 U of erythrocytes and platelets, respectively, versus 2.8±3.2 ( P =0.02) and 0.9±1.4 ( P =0.002) units in the control. In the aprotinin group, 53% of patients received transfusions, whereas 79% of controls were exposed to blood products ( P =0.02).

Conclusions— Intraoperative aprotinin decreases postoperative bleeding and the number of transfusions in patients undergoing CABG and treated with clopidogrel <5 days before surgery.

Does Clopidogrel Increase Blood Loss Following Coronary Artery Bypass Surgery?

BACKGROUND

Clopidogrel (Plavix) is a potent inhibitor of platelet aggregation used concomitantly with percutaneous coronary interventions and in patients with acute coronary syndromes. Its favorable effects on preventing thrombus formation may have deleterious effects on hemostasis in patients undergoing coronary surgery.

METHODS

Data were collected prospectively on 312 consecutive urgent or emergent coronary artery bypass patients from July 1999 through April 2001 at a tertiary care center. Patients were stratified into three groups: clopidogrel within 4 days of operation (n = 41), clopidogrel continued until 5 to 8 days before operation (n = 39), and clopidogrel discontinued more than 8 days before operation or were never taking clopidogrel (n = 232).

RESULTS

Preoperative and intraoperative characteristics were similar among all groups. Mediastinal and pericardial chest tube losses in the first 24 hours were 1,044 +/- 750 mL in the clopidogrel within 4 days group, 528 +/- 250 mL in the clopidogrel 5 to 8 days group, and 573 +/- 329 mL in the clopidogrel more than 8 days group (p < 0.01). The mean total blood product transfusions were 12.2 +/- 15.4 U, 1.2 +/- 2.0 U, and 2.6 +/- 5.7 U, respectively (p < 0.001). Reoperation for bleeding was noted in 14.6%, 2.6%, and 1.7%, respectively (p = 0.002). The median hospital lengths of stay for the three groups were 9 days, 7 days, and 7 days, respectively (p = 0.018). There were no statistically significant differences in mortality rate, myocardial infarction, stroke, mediastinitis, or postoperative renal failure among the groups. Multivariable analysis revealed that clopidogrel within 0 to 4 days of operation was an independent predictor of transfusion requirements (OR 4.22, 95% confidence interval [CI] 2.07, 9.34, p = 0.001), intensive care unit (ICU) length of stay (OR 3.14, 95% CI 1.40, 7.04, p = 0.006), and total hospital length of stay (coefficient 7.65, se 2.41, p = 0.002).

CONCLUSIONS

Clopidogrel within 4 days of coronary bypass surgery is associated with increased blood losses and reoperation for bleeding and, according to multivariable models, is an independent risk factor for increased transfusion requirements and prolonged ICU and hospital length of stay.

Effect of aprotinin on clinical outcomes in coronary artery bypass graft surgery: A systematic review and meta-analysis of randomized clinical trials

OBJECTIVE

Despite proven blood transfusion benefits, aprotinin may be underused in coronary artery bypass grafting. Reluctance to use aprotinin may stem from safety concerns. The current objective was to evaluate clinical outcomes (mortality, myocardial infarction, renal failure, stroke, atrial fibrillation) in patients undergoing coronary artery bypass grafting who receive aprotinin by performing a quantitative overview of published, randomized, controlled trials.

METHODS

MEDLINE, EMBASE, and PHARMLINE (1988-2001) and reference lists of relevant articles were searched for coronary artery bypass grafting studies. Criteria for data inclusion were as follows: (1) random allocation of study treatments, (2) placebo control, (3) enrollment only of patients undergoing coronary artery bypass grafting, (4) no combination with another experimental medication or device, and (5) prophylactic and continuous intraoperative use.

RESULTS

Data from 35 coronary artery bypass grafting trials (n = 3879) confirm that aprotinin reduces transfusion requirements (relative risk 0.61, 95% confidence interval 0.58-0.66) relative to placebo, with a 39% risk reduction. Aprotinin therapy was not associated with increased or decreased mortality (relative risk 0.96, 95% confidence interval 0.65-1.40), myocardial infarction (relative risk 0.85, 95% confidence interval 0.63-1.14), or renal failure (relative risk 1.01, 95% confidence interval 0.55-1.83) risk, but it was associated with a reduced risk of stroke (relative risk 0.53, 95% confidence interval 0.31-0.90) and a trend toward reduced atrial fibrillation (relative risk 0.90, 95% confidence interval 0.78-1.03).

CONCLUSIONS

Aprotinin reduces transfusion requirements. Concerns that aprotinin therapy is associated with increased mortality, myocardial infarction, or renal failure risk is not supported by data from published, randomized, placebo-controlled clinical trials. Evidence for a reduced risk of stroke and a tendency toward reduction of atrial fibrillation occurrence was observed in patients who received aprotinin.

Current status of antifibrinolytics in cardiopulmonary bypass and elective deep hypothermic circulatory arrest

Cardiopulmonary bypass (CPB) results in many physiologic derangements, including activation of the hemostatic and fibrinolytic pathways. Deep hypothermic circulatory arrest (DHCA) adds a further insult to the coagulation systems because it involves more extreme hypothermia and organ ischemia related to blood stasis. The abnormalities induced by CPB disrupt the checks and balances in the hemostatic and fibrinolytic systems, resulting in a pathologic state that leads to excessive bleeding and other perioperative complications. Prophylactic antifibrinolytic therapy can attenuate the response to this insult by restoring the delicate balance within these systems, potentially reducing the complication rate and improving patient outcomes.

Efficacy of aprotinin in reducing blood loss in spinal fusion for idiopathic scoliosis

Aprotinin is a proteinase inhibitor with antifibrinolytic properties that has found widespread application during cardiac surgical procedures due to its ability to decrease blood loss and transfusion requirements. Recently it has been used by orthopedic surgeons in hip replacement and other major surgeries except for scoliosis surgery, which is known to be associated with major blood loss. To evaluate the effect of aprotinin in reducing blood loss during spinal fusion surgery for idiopathic scoliosis, a double-blind randomized prospective clinical study was performed. Forty-three patients with idiopathic scoliosis underwent spinal fusion and instrumentation and were divided randomly into two groups. Fifteen patients received aprotinin, whereas 28 patients received placebo. The aprotinin group had less blood loss than the placebo group. The transfusion requirement was less in the aprotinin group than the placebo group. Although the difference was not significant statistically, the benefit of aprotinin in reducing blood loss in spinal surgery for idiopathic scoliosis was consistent.

Aprotinin restores the adhesive capacity of dysfunctional platelets

The post-operative coagulopathy associated with cardiopulmonary bypass (CPB) is known to be predominantly related to platelet dysfunction. The use of the serine protease inhibitor aprotinin dramatically reduces CPB associated hemorrhage and is thought to act primarily through the inhibition of plasmin without directly influencing platelets. Our data indicate that there is a direct effect of aprotinin on platelet adhesion, which has not been previously reported. We found that when aprotinin was added to blood samples with poorly adhesive platelets, platelet adhesion significantly increased as measured by the percent coverage of denuded arterial segments in the Baumgartner perfusion chamber. In preliminary experiments using expired platelet concentrates or fresh whole blood, the addition of aprotinin induced a positive increase of 22+/-7.5 and 14+/-6.2 percentage point in platelet adhesion, respectively. A simulated CPB model that recirculated a unit of anticoagulated whole blood for 2 h was used (n=14) to induce a platelet adhesion defect similar to that seen in clinical CPB. At initiation of recirculation, platelet adhesion was 55+/-9.5% but dropped to 13+6.5% coverage after 2 h simulated CPB. The addition of aprotinin to the post-recirculation samples induced a significant restoration of platelet adhesion back to 38+/-11% coverage. When epsilon amino-caproic acid with soybean trypsin inhibitor was added to post recirculation samples, there was no similar effect on adhesion scores. To compare these findings with surgical CPB, we collected one blood sample at the beginning and two at the end of CPB from each of seven open-heart patients. Aprotinin was added to one of each of the post-CPB samples. Platelet adhesion at the onset of surgical CPB was only 39+/-11% in this patient group but dropped to 7+/-7% by the end. Similar to the model, the addition of aprotinin post-CPB restored adhesion to 29+/-11%. These results suggest some action of aprotinin other than its antiplasmin effect, and that platelet adhesion in general can be promoted by aprotinin.

Anesthetic and perfusion issues in contemporary pediatric cardiac surgery

As the fields of pediatric cardiology and cardiac surgery advance in complexity and in accountability for clinical and economic outcomes, several issues traditionally associated with the operating room are becoming important to physicians, nurses, and respiratory therapists who take care of children after cardiac surgery. The article discusses the concepts of "fast track" cardiac surgery, regional anesthetic techniques, coagulopathies and bleeding after cardiopulmonary bypass, intraoperative ultrafiltration, and mechanical circulatory assist devices.

The effect of clopidogrel in combination with aspirin when given before coronary artery bypass grafting

OBJECTIVES

This study was designed to evaluate the effect of preoperative clopidogrel on coronary artery bypass graft surgery (CABG) outcomes.

BACKGROUND

Clopidogrel in combination with aspirin, given before percutaneous coronary intervention, has become the standard for stent thrombosis prevention. Some premedicated patients, however, are found to have surgical disease on angiography, and irreversible platelet inhibition becomes a concern for upcoming CABG.

METHODS

We prospectively studied 224 consecutive patients undergoing nonemergent first-time CABG, and compared those with preoperative clopidogrel exposure within seven days (n = 59) to those without exposure (n = 165).

RESULTS

The groups were comparable in age, gender, body surface area, preoperative hematocrit, preoperative prothrombin time and prior myocardial infarction. The clopidogrel group had higher 24-h mean chest tube output (1,224 ml vs. 840 ml, p = 0.001), and more transfusions of red blood cells (2.51 U vs. 1.74 U, p = 0.036), platelets (0.86 U vs. 0.24 U, p = 0.001) and fresh frozen plasma (0.68 U vs. 0.24 U, p = 0.015). Moreover, reoperation for bleeding was 10-fold higher in the clopidogrel group (6.8% vs. 0.6%, p = 0.018). The clopidogrel group also had less extubation within 8 h (54.2% vs. 75.8%, p = 0.002) and a trend towards less hospital discharge within five days (33.9% vs. 46.7%, p = 0.094).

CONCLUSIONS

Clopidogrel in combination with aspirin before CABG is associated with higher postoperative bleeding and morbidity. These findings raise concern regarding the routine administration of clopidogrel before anticipated coronary stent implantation.

Aspirin and postoperative bleeding after coronary artery bypass grafting

OBJECTIVE

To evaluate the relationship between aspirin ingestion and postoperative bleeding complications, and to test the hypothesis that there is a subset of patients who are aspirin hyperresponders with a proclivity toward platelet dysfunction.

SUMMARY BACKGROUND DATA

Despite numerous retrospective and prospective analyses, it is still controversial as to whether aspirin ingestion before coronary artery bypass grafting (CABG) is associated with significant postoperative bleeding.

METHODS

Between January 1995 and December 1999, the records of 2,606 consecutive patients undergoing CABG were reviewed to identify patients with a history of aspirin ingestion up until the time of surgery. Aspirin ingestion was correlated with postoperative blood transfusion using multivariate analysis. In a subset of preoperative aspirin users (n = 40), bleeding times were measured before and after aspirin use. Flow cytometry was performed in another cohort of patients with known heart disease (n = 30) to determine the effect of aspirin on platelet surface receptors.

RESULTS

During the 5-year study period, 63% of the CABG patients were identified as aspirin users. Among these, 23.1% required blood transfusions compared with 19% for the nonusers. Non-red blood cell transfusions were more common in aspirin users, as was reexploration for bleeding. Stratification of these results according to the frequency of aspirin use showed that aspirin is an independent multivariate predictor of postoperative blood transfusion only in high-risk patients. In the prospective studies, aspirin treatment resulted in a significant increase in the template bleeding time, an increase in platelet PAR-1 thrombin receptor activity, and a decrease in the binding of platelets to monocytes.

CONCLUSIONS

The findings support the hypothesis that aspirin is associated with a greater likelihood of postoperative bleeding. A platelet function testing algorithm that combines preoperative risk factor assessment, template bleeding times, and flow cytometry may allow the identification of aspirin hyperresponders who are at increased risk for bleeding.

Tranexamic acid in aortic valve replacement

OBJECTIVE

To assess the relative efficacy of tranexamic acid compared with a control group to decrease bleeding and transfusion requirements in a uniform population undergoing aortic valve replacement.

DESIGN

Prospective, randomized, double-blind study.

SETTINGS

University hospital.

PARTICIPANTS

Adult cardiac surgery patients (n = 300).

INTERVENTIONS

Patients were randomized into 2 groups to receive either a total of 5 g of tranexamic acid or a saline solution. Bleeding in the postoperative period, transfusions of bank blood products, coagulation profile, intensive care unit stay, and hospital length of stay were recorded.

MEASUREMENTS AND MAIN RESULTS

Postoperative bleeding in patients treated with tranexamic acid was significantly lower compared with the control group (p < 0.0001). Packed red blood cells and fresh frozen plasma usage were reduced in the tranexamic acid group compared with the control group (p = 0.0095 and p < 0.0001). Only 24.5% of tranexamic acid patients received blood products versus 45% of control patients (p < 0.01). There was no significant difference in hematologic and coagulation profiles after the operation between the groups.

CONCLUSIONS

Tranexamic acid reduces postoperative blood loss and transfusion requirements in elective aortic valve replacement.

Reduction of hepatic reperfusion injury by antithrombin III and aprotinin

Disturbance in hepatic microcirculation and leucocyte-endothelium interaction after warm ischaemia represents one of the leading mechanisms for postoperative organ dysfunction. Recent studies have shown that pretreatment with antithrombin III (AT III) and aprotinin reduces the leucocyte-endothelium interaction in ischaemic small intestine and during extracorporal circulation in cardiac surgery. Standardized warm hepatic ischaemia and intravital fluorescence videomicroscopy was performed in an experimental study with rats. Animals were pretreated with AT III or aprotinin. Analysis of intravital videomicroscopy showed that the hepatic microcirculation after warm hepatic ischaemia in rats was significantly enhanced by AT III and aprotinin, most likely by reducing the leucocyte-endothelium interaction. We concluded that drug application before the Pringle manoeuvre might reduce the reperfusion damage after liver resection.

Ultra-low dose aprotinin decreases transfusion requirements and is cost effective in coronary operations

BACKGROUND

The recommended dose of aprotinin has been shown to reduce blood loss and need for blood transfusions, but the cost precludes its routine use. This study was designed to determine whether a less expensive, ultra-low dose of aprotinin is effective when used in coronary artery bypass grafting with left internal mammary artery.

METHODS

Patients (n = 202) were randomized to receive either placebo or aprotinin, 0.5 million KIU before incision and 0.5 million KIU during initiation of cardiopulmonary bypass. Differences in quantity of blood transfused were analyzed. Further groups were analyzed to account for the effect of aspirin. Multivariable analysis was performed to determine risk factors for transfusion. Direct costs of blood products and aprotinin were tabulated for each group.

RESULTS

There was an important reduction in the proportion of patients transfused, and number of blood units transfused when aprotinin was given before coronary artery bypass grafting. These differences were even more important in patients on aspirin preoperatively. Independent predictors for increased number of transfusions were aspirin continued before operation, smaller body surface area, and the use of placebo instead of ultra-low dose aprotinin. There was no difference in morbidity between treatment groups. There was a reduction in direct costs associated with the use of aprotinin.

CONCLUSIONS

These data support the routine use of aprotinin 1 million KIU in coronary artery bypass grafting with left internal mammary artery to reduce cost and transfusion requirements.

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.

SMA circuits reduce platelet consumption and platelet factor release during cardiac surgery

BACKGROUND

Platelet count and function are particularly damaged by cardiopulmonary bypass (CPB). This study evaluated the effects of a novel CPB circuit in terms of platelet count and activation, and postoperative need for blood products.

METHODS

One hundred patients undergoing coronary grafting were randomized in two groups: control group (n = 50) and test group (n = 50, surface modifying additives circuit, SMA group). Blood samples were taken before, during, and after CPB. Postoperative blood loss, number of transfused blood products, and postoperative variables were recorded.

RESULTS

The platelet count decreased less in the SMA group compared to the control group (end of CPB: respectively, 165 +/- 9 x 10(3)/mm3 vs 137 +/- 8 x 10(3)/mm3; p < 0.01). This was paralleled by a reduction in beta-thromboglobulin plasma levels in the SMA group. There was a trend to decreased blood loss in the SMA group, but the difference was significant only in patients taking aspirin preoperatively (p < 0.05). In the SMA group nearly 50% less fresh frozen plasma and platelet units were administered (p < 0.01). No operative deaths were observed.

CONCLUSIONS

The use of circuits with surface additives is clinically safe, preserves platelet levels, and attenuates platelet activation. This may lead to a reduced need for blood products.

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

OBJECTIVE

Since excessive fibrinolysis during cardiac surgery is frequently associated with abnormal perioperative bleeding, many authors have advocated prophylactic use of antifibrinolytic drugs to prevent hemorrhagic disorders. We compared the effects of tranexamic acid (a synthetic antifibrinolytic drug) with aprotinin (a natural derivative product with antifibrinolytic properties) on perioperative bleeding and the need for allogeneic transfusions.

METHODS

In a single-center prospective randomized unblinded trial, 1040 consecutive patients undergoing primary, elective cardiac operations with cardiopulmonary bypass received either high-dose aprotinin or tranexamic acid. The aprotinin group (518 patients) received 280 mg in 20 minutes before the skin incision, 280 mg in the priming solution of the extracorporeal circuit, and a continuous infusion of 70 mg/h throughout the operation. The tranexamic acid group (522 patients) received 1 g in 20 minutes before the skin incision, 500 mg in the priming solution of the extracorporeal circuit, and a continuous infusion of 400 mg/h during the operation. Postoperative bleeding, perioperative transfusions, and hematologic variables were evaluated at fixed times. Postoperative thrombotic complications, intubation time, intensive care unit stay, and hospital stay were recorded.

RESULTS

Postoperative bleeding was similar in the 2 groups: aprotinin 250 mL (150-400 mL) versus tranexamic acid 300 mL (200-450 mL) (median and 25th-75th quartiles), median difference of 50 mL (95% confidence intervals, 0-50 mL). The number of transfusions and the outcome did not differ.

CONCLUSIONS

Tranexamic acid and aprotinin show similar clinical effects on bleeding and allogeneic transfusion in patients undergoing primary elective heart operations. Since tranexamic acid is about 100 times cheaper than aprotinin, its use is preferable in this type of patient.

Comparison of two doses of aprotinin in patients receiving aspirin before coronary bypass surgery

This study was designed to evaluate efficacy and tolerability of two different doses of aprotinin in patients receiving aspirin before undergoing coronary artery bypass grafting. Forty-two patients were randomized to receive either placebo (group I), or aprotinin in doses of 4,000,000 KIU (group II) or 6,000,000 KIU (group III). Drug efficacy was determined by measuring postoperative blood loss and transfusion of blood products. Both doses were effective in reducing blood loss and transfusion requirements. Blood loss through thoracotomy drainage was 450 +/- 224, 182 +/- 144, 142 +/- 98 ml, respectively, for control and treatment groups II and III (p = 0.0001). The numbers of patients with blood transfusions were seven (50%), two (17%) and two (17%) for group I and treatment groups II and III, respectively (p = 0.10). Tolerability was excellent and complications few and reversible. In conclusion, high and medium doses of aprotinin were well tolerated and reduced bleeding and transfusion requirements in patients submitted to coronary bypass surgery under the effects of aspirin.