Operations on the thoracic aorta and hypothermic circulatory arrest: is aprotinin safe?

Drugs to reduce bleeding and transfusion in major open vascular or endovascular surgery: a systematic review and network meta-analysis

BACKGROUND

Vascular surgery may be followed by internal bleeding due to inadequate surgical haemostasis, abnormal clotting, or surgical complications. Bleeding ranges from minor, with no transfusion requirement, to massive, requiring multiple blood product transfusions. There are a number of drugs, given systemically or applied locally, which may reduce the need for blood transfusion.

OBJECTIVES

To assess the effectiveness and safety of anti-fibrinolytic and haemostatic drugs and agents in reducing bleeding and the need for blood transfusion in people undergoing major vascular surgery or vascular procedures with a risk of moderate or severe (> 500 mL) blood loss.

SEARCH METHODS

We searched: Cochrane Central Register of Controlled Trials; MEDLINE; Embase; CINAHL, and Transfusion Evidence Library. We also searched the WHO ICTRP and ClinicalTrials.gov trial registries for ongoing and unpublished trials. Searches used a combination of MeSH and free text terms from database inception to 31 March 2022, without restriction on language or publication status.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in adults of drug treatments to reduce bleeding due to major vascular surgery or vascular procedures with a risk of moderate or severe blood loss, which used placebo, usual care or another drug regimen as control.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were units of red cells transfused and all-cause mortality. Our secondary outcomes included risk of receiving an allogeneic blood product, risk of reoperation or repeat procedure due to bleeding, risk of a thromboembolic event, risk of a serious adverse event and length of hospital stay. We used GRADE to assess certainty of evidence.

MAIN RESULTS

We included 22 RCTs with 3393 participants analysed, of which one RCT with 69 participants was reported only in abstract form, with no usable data. Seven RCTs evaluated systemic drug treatments (three aprotinin, two desmopressin, two tranexamic acid) and 15 RCTs evaluated topical drug treatments (drug-containing bioabsorbable dressings or glues), including fibrin, thrombin, collagen, gelatin, synthetic sealants and one investigational new agent. Most trials were conducted in high-income countries and the majority of the trials only included participants undergoing elective surgery. We also identified two ongoing RCTs. We were unable to perform the planned network meta-analysis due to the sparse reporting of outcomes relevant to this review. Systemic drug treatments We identified seven trials of three systemic drugs: aprotinin, desmopressin and tranexamic acid, all with placebo controls. The trials of aprotinin and desmopressin were small with very low-certainty evidence for all of our outcomes. Tranexamic acid versus placebo was the systemic drug comparison with the largest number of participants (2 trials; 1460 participants), both at low risk of bias. The largest of these included a total of 9535 individuals undergoing a number of different higher risk surgeries and reported limited information on the vascular subgroup (1399 participants). Neither trial reported the number of units of red cells transfused per participant up to 30 days. Three outcomes were associated with very low-certainty evidence due to the very wide confidence intervals (CIs) resulting from small study sizes and low number of events. These were: all-cause mortality up to 30 days; number of participants requiring an allogeneic blood transfusion up to 30 days; and risk of requiring a repeat procedure or operation due to bleeding. Tranexamic acid may have no effect on the risk of thromboembolic events up to 30 days (risk ratio (RR) 1.10, 95% CI 0.88 to 1.36; 1 trial, 1360 participants; low-certainty evidence due to imprecision). There is one large ongoing trial (8320 participants) comparing tranexamic acid versus placebo in people undergoing non-cardiac surgery who are at high risk of requiring a red cell transfusion. This aims to complete recruitment in April 2023. This trial has primary outcomes of proportion of participants transfused with red blood cells and incidence of venous thromboembolism (DVT or PE). Topical drug treatments Most trials of topical drug treatments were at high risk of bias due to their open-label design (compared with usual care, or liquids were compared with sponges). All of the trials were small, most were very small, and few reported clinically relevant outcomes in the postoperative period. Fibrin sealant versus usual care was the topical drug comparison with the largest number of participants (5 trials, 784 participants). The five trials that compared fibrin sealant with usual care were all at high risk of bias, due to the open-label trial design with no measures put in place to minimise reporting bias. All of the trials were funded by pharmaceutical companies. None of the five trials reported the number of red cells transfused per participant up to 30 days or the number of participants requiring an allogeneic blood transfusion up to 30 days. The other three outcomes were associated with very low-certainty evidence with wide confidence intervals due to small sample sizes and the low number of events, these were: all-cause mortality up to 30 days; risk of requiring a repeat procedure due to bleeding; and risk of thromboembolic disease up to 30 days. We identified one large trial (500 participants) comparing fibrin sealant versus usual care in participants undergoing abdominal aortic aneurysm repair, which has not yet started recruitment. This trial lists death due to arterial disease and reintervention rates as primary outcomes.

AUTHORS' CONCLUSIONS

Because of a lack of data, we are uncertain whether any systemic or topical treatments used to reduce bleeding due to major vascular surgery have an effect on: all-cause mortality up to 30 days; risk of requiring a repeat procedure or operation due to bleeding; number of red cells transfused per participant up to 30 days or the number of participants requiring an allogeneic blood transfusion up to 30 days. There may be no effect of tranexamic acid on the risk of thromboembolic events up to 30 days, this is important as there has been concern that this risk may be increased. Trials with sample size targets of thousands of participants and clinically relevant outcomes are needed, and we look forward to seeing the results of the ongoing trials in the future.

Evaluating the Quality of Trials of Hypothermic Circulatory Arrest Aortic Surgery

The quality of level 1 evidence in reports on deep hypothermic circulatory arrest was assessed, and the confounding factors in surgical management and study design that can prevent meta-analysis formulation were determined. A systematic search of the literature was conducted using categorized nomenclature for randomized controlled trials in adult patients undergoing deep hypothermic circulatory arrest in the last 40 years. Twelve randomized controlled trials (2.3%) were found among 504 publications on deep hypothermic circulatory arrest listed on Medline from 1960; only 4 of them related to adults. One adequately powered study demonstrated reduced blood loss in deep hypothermic circulatory arrest using aprotinin. Three studies comparing retrograde and antegrade perfusion were underpowered. The median CONSORT score was 14 (range, 13–15). There were no consistent measures of similar outcomes (neuropsychometric, neurocognitive). No explanation was provided for the difference in reported ranges of neurological deficits in nonrandomized (5%–70%) and randomized (3%–9%) studies. Existing studies of deep hypothermic circulatory arrest are insufficient and inconsistent in the outcome measured, which explains the lack of a meta-analysis. Neurological injury remains high, and an appropriately powered study of interventions that can optimize cerebral perfusion is necessary.

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. This version of the review includes a sensitivity analysis excluding trials authored by Prof. Joachim Boldt.

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.

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.

Managing fibrinolysis without aprotinin

Cardiopulmonary bypass increases perioperative bleeding and produces a consumptive coagulopathy, which is defined as the simultaneous production of thrombin and fibrinolysis. Thrombin formation and fibrinolysis primarily occur in the surgical wound and peak at the time heparin is reversed by protamine. Neither aprotinin nor lysine analogs successfully control bleeding in many complex procedures, reoperations, aortic resections, or in implantations of mechanical circulatory devices. This analysis reviews the mechanisms involved and current treatment protocols, with the conclusion that changes in treatment protocols rather than use of a specific anti-fibrinolytic drug may provide better control of bleeding in these patients.

Aprotinin and renal dysfunction

Aprotinin is a polypeptide serine protease inhibitor used to prevent bleeding and need for transfusions in patients having heart surgery. A recent analysis of an observational study data set suggested the use of aprotinin was associated with an increased risk of developing renal failure. The present article reviews the data from basic science studies in tissues, animals and man together with the data from observational studies and randomised controlled trials. The interpretation of the data is hampered owing to the use of different endpoints to describe mild/moderate renal impairment. Nonetheless, the evidence points to aprotinin use being associated with a transient small rise in plasma creatinine concentration in certain patients. There is no evidence for an increased risk of developing new renal failure requiring dialysis/renal replacement therapy.

Aprotinin and renal dysfunction after pediatric cardiac surgery

BACKGROUND

Aprotinin is a potent antifibrinolytic drug, which reduces postoperative bleeding and transfusion requirements. Recently, two observational studies reported increased incidence of renal dysfunction after aprotinin use in adults. Therefore, the aim of the study was to investigate the safety of aprotinin use in pediatric cardiac surgery patients.

METHODS

Data were prospectively and consecutively collected from 657 pediatric patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). The database was assessed with regard to a possible relationship between aprotinin administration and dialysis and between aprotinin and postoperative renal dysfunction [defined as 25% decrease in the creatinine clearance (Ccr) compared with the preoperative value] by propensity-score adjustment and multivariable methods.

RESULTS

The incidence of dialysis (9.6% vs 4.1%; P = 0.005) and renal dysfunction (26.3% vs 16.1%; P = 0.019) was higher in patients who received aprotinin; however, propensity adjusted risk ratios were not significant [odds ratio (OR) of dialysis: 1.22; 95% confidence interval (CI) 0.46-3.22; OR of renal dysfunction 1.26; 95% CI: 0.66-1.92]. Aprotinin significantly reduced blood loss in the first postoperative 24 h. The main contributors of renal dysfunction were CPB duration, cumulative inotropic support, age, preoperative Ccr, amount of transfusion and pulmonary hypertension.

CONCLUSIONS

Despite the higher incidences of renal dysfunction and failure in the aprotinin group, an independent role of the drug in the development of renal dysfunction or dialysis could not be demonstrated in pediatric cardiac patients undergoing CPB.

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.

Renal function and dysfunction

Recent publications regarding perioperative renal dysfunction provide a 'potpourri' of topics worthy of discussion. The risk of perioperative renal dysfunction is higher in patients with heart failure, but other pre-existing conditions, such as genetic polymorphism, may have prognostic implications. Evaluation of renal risk and protective interventions are discussed for a number of specific operative entities, including cardiac surgery (with or without cardiopulmonary bypass), aortic surgery and renal revascularization. New publications on a wide variety of nephrotoxic insults are presented, including antifibrinolytic agents, obstructive jaundice, prostaglandin inhibitors, cyclosporine A, radiocontrast dyes and volatile anesthetic agents. Renal transplantation is discussed as a specific entity. Finally, we discuss recent papers describing outcome in patients in chronic renal failure undergoing cardiac surgery.

Aprotinin use in thoracic aortic surgery: Safety and outcomes

OBJECTIVES

Previous studies of aprotinin use in thoracic aortic surgery, limited in size and design, reported minimal information regarding outcomes other than blood loss and transfusion. The evaluation of impact of aprotinin on surgical outcomes in a large sample is needed.

METHODS

Patients at Yale New Haven Hospital undergoing thoracic aortic surgery (aneurysm repair, dissections, penetrating ulcers, intramural hematomas) between 1995 and 2003 were considered for inclusion. Each patient receiving aprotinin was matched to a control per preoperative profile (age, gender, urgency of surgery, dissection/location of aortic disease). Data (surgical specifics, demographic variables, comorbidities, disease location-related variables, preoperative medications, intraoperative medications, surgical/operative data) were abstracted from the records of successfully matched aprotinin-treated patients and controls (n = 168). Comparison and determination of success of matching were performed using bivariate analyses. Outcome variables were compared using statistical tests for paired data. Supplementary unpaired and regression analyses were also performed.

RESULTS

Baseline demographics of groups were similar, although controls had reduced history of aortic disease, but greater intraoperative use of lysine analogs (P < .05). Aprotinin significantly reduced platelet transfusion (P < .05). Paired bivariate analyses showed a tendency toward reduced ventilation time, pulmonary complications, and permanent arrhythmias (P < .05) associated with aprotinin. Supplementary analyses were supportive only for pulmonary complications and permanent arrhythmias.

CONCLUSIONS

The current evaluation substantiates previous reports that aprotinin may be safe to use and likely to improve some outcomes of thoracic aortic surgery. However, further studies for rare safety and efficacy end points are warranted.

Renal dysfunction after thoracic aortic surgery requiring deep hypothermic circulatory arrest: definition, incidence, and clinical predictors

OBJECTIVE

The purpose of this study was to evaluate renal dysfunction (RD) after thoracic aortic surgery (TAS) requiring deep hypothermic circulatory arrest (DHCA), to determine the influence of definition on RD after TAS-DHCA, to determine univariate predictors of RD after TAS-DHCA, and to determine multivariate predictors for RD TAS-DHCA. RD was defined in 3 ways: (1) >25% reduction in creatinine clearance, (2) >50% increase in serum creatinine, and (3) >50% increase in serum creatinine with an abnormal peak serum creatinine (>1.3 mg/dL for men and >1.0 mg/dL for women).

STUDY DESIGN

Retrospective and observational.

STUDY SETTING

Single large university hospital.

PARTICIPANTS

All adults requiring TAS-DHCA in 2000 and 2001.

MAIN RESULTS

The cohort size was 144. Antifibrinolytic exposure was 100%: aprotinin 66% and aminocaproic acid 34%. The incidence of RD TAS-DHCA was 22.9% to 38.2%, depending on the definition. The incidence of renal replacement therapy was 2.8%. Multivariate predictors for RD after TAS-DHCA were sepsis, aprotinin exposure, preoperative hypertension, age, and donor exposures.

CONCLUSIONS

Although RD after TAS-DHCA varies substantially because of definition, it is still very common. Its multivariate predictors merit further focused research to enhance perioperative protection of the kidney.

Perioperative Outcome in Adults Undergoing Elective Deep Hypothermic Circulatory Arrest With Retrograde Cerebral Perfusion in Proximal Aortic Arch Repair: Evaluation of Protocol-Based Care

OBJECTIVE

The purpose of this study was to describe perioperative outcome in adults undergoing elective proximal aortic arch repair with protocol-based deep hypothermic circulatory arrest (DHCA) with retrograde cerebral perfusion (RCP).

DESIGN

Retrospective and observational.

SETTING

Cardiothoracic operating rooms and intensive care unit.

PARTICIPANTS

Seventy-nine consecutive adults undergoing elective proximal aortic arch repair with DHCA (1999-2001).

INTERVENTIONS

None.

MAIN RESULTS

Average age of the patients was 64.9 years. Mean circulatory arrest time was 30.4 +/- 8.5 minutes. Perioperative mortality was 7.6%. Perioperative stroke incidence was 3.8%. Tracheal extubation was successful in 87.3% of patients within 24 hours of operation. Of the cohort, 80.8% were discharged from the intensive care unit within 72 hours of surgery. Median length of hospital stay was 7.4 days. Repeat mediastinal exploration because of bleeding occurred in 3.8% of patients. Although perioperative renal dysfunction (defined as >1.5-fold increase in plasma creatinine concentration) developed in 24.0% of patients, only 3.8% required dialysis.

CONCLUSIONS

The above parameters establish a baseline incidence for major perioperative complications in adults undergoing elective DHCA with RCP for elective proximal aortic arch repair. In approaching the open aortic arch for short periods of circulatory arrest, deep hypothermia with adjunctive RCP is safe and effective.

Clinical Predictors for Prolonged Intensive Care Unit Stay in Adults Undergoing Thoracic Aortic Surgery Requiring Deep Hypothermic Circulatory Arrest

OBJECTIVE

The purpose of this study was to describe clinical predictors for prolonged length of stay in the intensive care unit (PLOS-ICU) after adult thoracic aortic surgery requiring standardized deep hypothermic circulatory arrest (DHCA); and to determine the incidence of PLOS-ICU after DHCA, univariate predictors for PLOS-ICU, and multivariate predictors for PLOS-ICU.

STUDY DESIGN

A retrospective and observational study. PLOS-ICU was defined as longer than 5 days in the ICU.

STUDY SETTING

Cardiothoracic operating rooms and the ICU.

PARTICIPANTS

All adults requiring thoracic aortic repair with DHCA INTERVENTIONS: None.

MAIN RESULTS

The cohort size was 144. The incidence of PLOS-ICU was 27.8%. The mortality rate was 11.1%. Univariate predictors for PLOS-ICU were age, stroke, DHCA duration, vasopressor dependence >72 hours, mediastinal re-exploration for bleeding, and renal dysfunction. Multivariate predictors for PLOS-ICU were stroke, vasopressor dependence >72 hours, and renal dysfunction.

CONCLUSIONS

PLOS-ICU after DHCA is common. The identified multivariate predictors merit further hypothesis-driven research to enhance perioperative protection of the brain, kidney, and cardiovascular system.

Major Clinical Outcomes in Adults Undergoing Thoracic Aortic Surgery Requiring Deep Hypothermic Circulatory Arrest: Quantification of Organ-Based Perioperative Outcome and Detection of Opportunities for Perioperative Intervention

OBJECTIVE

The purpose of this study was to describe clinical outcome after adult thoracic aortic surgery requiring standardized deep hypothermic circulatory arrest (DHCA), to determine mortality and length of stay, neurologic outcome, cardiorespiratory outcome, and hemostatic and renal outcome after DHCA.

DESIGN

Retrospective and observational.

SETTING

Cardiothoracic operating rooms and intensive care unit (ICU).

PARTICIPANTS

All adults requiring thoracic aortic repair with DHCA.

INTERVENTIONS

None. The study was observational.

MAIN RESULTS

The cohort size was 110. All patients received an antifibrinolytic. The mortality rate was 8.2%. The mean length of stay was 6.8 days (ICU) and 14.0 days (hospital). The incidence of stroke was 8.1% and postoperative delirium was 10.9%. The rate of postoperative atrial fibrillation was 43.6%; 19.1% required postoperative mechanical ventilation longer than 72 hours. Chest tube drainage was 931 mL for the first 24 hours. Postoperative dialysis was required in 1.8% of patients. Renal dysfunction occurred in 40% to 50% of patients, depending on the definition.

CONCLUSIONS

The protocol for DHCA at the authors' institution is associated with superior or equivalent perioperative outcomes to those reported in the literature. This study identified the need for further quantification of the clinical outcomes after DHCA in order to prioritize outcome-based hypothesis-driven prospective intervention in DHCA.

Antifibrinolytic agents in cardiac surgery: Current controversies

Antifibrinolytic agents play a prominent role in adult cardiac surgery. This article is a review of the modern published experience of antifibrinolytic agent use in adult cardiac surgery. The use of tranexamic acid, epsilon-aminocaproic acid, and aprotinin is examined during primary cardiac surgery, deep hypothermic circulatory arrest, reoperative cardiac surgery, and off-pump coronary artery bypass surgery. In addition, the issues of vein graft patency and hypersensitivity reaction in the presence of antifibrinolytic agents are examined.

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.

Hemostatic effects of tranexamic acid in elective thoracic aortic surgery: a prospective, randomized, double-blind, placebo-controlled study

OBJECTIVE

We studied the hemostatic effects of tranexamic acid in patients undergoing elective surgery involving the thoracic aorta.

METHODS

In a double-blind, randomized fashion, 60 consecutive patients were assigned to two treatment groups: 30 patients (placebo group) received infusion of saline solution, and 30 (treatment group) received tranexamic acid (1 g before skin incision, an infusion of 400 mg/h during the operation, and 500 mg in the pump priming). Perioperative bleeding was considered as a primary outcome. Perioperative allogeneic transfusions, major thrombotic complications (myocardial infarction, pulmonary embolism, renal insufficiency), and surgical outcomes were also considered.

RESULTS

Patients treated with tranexamic acid showed significant reductions in postoperative bleeding, both in terms of the amount collected during the first 4 postoperative hours (median 307 mL, interquartile range 253-361 mL in the placebo group vs median 211 mL, interquartile range 108-252 mL in the treatment group, P =.002) and in terms of total bleeding (median 722 mL, interquartile range 574-952 mL in the placebo group vs median 411 mL, interquartile range 313-804 mL in the treatment group, P =.04). Consequently, the number of patients transfused differed significantly between groups (21 patients [72.4%] in the placebo group vs 13 [44.8%] in the treatment group, P =.033). Patients in the treatment group showed significant reductions in the total amount for the entire group of packed red cells transfused (13,500 mL in the treatment group vs 28,000 mL in the placebo group, P =.012) and in the total amount of allogeneic transfusions (23,400 mL in the treatment group vs 53,000 mL in the placebo group, P =.024). No differences in perioperative thrombotic complications were found.

CONCLUSIONS

In this initial series of patients undergoing thoracic aortic surgery, tranexamic acid appeared effective in reducing perioperative bleeding, with a significant reduction in the need for allogeneic transfusions and without any increased risk of thrombotic complications.

Aprotinin and deep hypothermic cardiopulmonary bypass with or without circulatory arrest for craniotomy

Deep hypothermic cardiopulmonary bypass with or without circulatory arrest has been used to facilitate the surgical repair of complex cerebrovascular lesions. The advantages of deep hypothermia have been tempered by the occurrence of coagulopathy that is associated with substantial morbidity and mortality. This study analyzed retrospectively the records of 13 patients who underwent cerebrovascular neurosurgery using deep hypothermic cardiopulmonary bypass with or without circulatory arrest during the period 1993 through 1999. All patients received the serine protease inhibitor aprotinin in an effort to avoid the development of a coagulopathy, defined as hemorrhage requiring reoperation. No patients developed postoperative intracranial hemorrhage. There was also no evidence of renal dysfunction, deep venous thrombosis, myocardial infarction, or pulmonary embolism. In conclusion, this study suggests that aprotinin may be beneficial to avoid the coagulopathy that is more likely to occur if deep hypothermic cardiopulmonary bypass with or without circulatory arrest is used for craniotomy without adverse effects on renal function or apparent thrombotic complications.

Inflammation After Cardiopulmonary Bypass: Therapy for the Postpump Syndrome

Cardiopulmonary bypass (CPB) is used in most, but not all, complex heart operations. CPB is associated with a systemic inflammatory response in adults and children. Many materials-dependent (exposure of blood to non- physiologic surfaces and conditions) and materials-in dependent (surgical trauma, ischemia-perfusion to the organs, changes in body temperature, and release of endotoxin) factors during CPB have been implicated in the etiology of this complex response. The mechanisms involved may include complement activation, release of cytokines, leukocyte activation with expression of ad hesion molecules, and production of various vasoactive and immunoactive substances. Postpump inflamma tion may lead to postoperative complications and may result in respiratory failure, renal dysfunction, bleeding disorders, neurologic dysfunction, altered liver func tion, and ultimately multiple organ failure. Significant efforts are being made to decrease the generation and effects of postpump inflammation. Interventions to this end have included avoiding CPB when possible, im proving the biocompatibility of the involved mechani cal devices, and administering medications that main tain cellular integrity. This article provides an overview of the etiology, pathophysiology, and treatment of postpump inflammation. Perhaps with additional in sight into this syndrome, CPB can be made a safer and more efficacious modality of cardiorespiratory support. Copyright© 2001 by W.B. Saunders Company.

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.

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.

The effects of aprotinin on blood product transfusion associated with thoracic aortic surgery requiring deep hypothermic circulatory arrest

OBJECTIVE

To compare the effects of aprotinin on blood product use and postoperative complications in patients undergoing thoracic aortic surgery requiring deep hypothermic circulatory arrest.

DESIGN

A retrospective study.

SETTING

A university hospital.

PARTICIPANTS

Nineteen patients who underwent elective or urgent thoracic aortic surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The total number of units of packed red blood cells, fresh frozen plasma, and platelets was significantly less in the group that received aprotinin (p = 0.01, 0.04, and 0.01). The intraoperative transfusion of packed red blood cells and platelets, collection and retransfusion of cell saver, and postoperative transfusion of fresh frozen plasma were also significantly less in the aprotinin group (p = 0.01, 0.02, 0.01, and 0.05). No patient in either group sustained renal dysfunction or a myocardial infarction. Two patients who had not received aprotinin suffered from chronic postoperative seizures, and one patient who had received aprotinin sustained a perioperative stroke.

CONCLUSIONS

Low-dose aprotinin administration significantly decreases blood product transfusion requirements in the setting of thoracic aortic surgery requiring deep hypothermic circulatory arrest, and it does not appear to be associated with renal or myocardial dysfunction.

Aprotinin in deep hypothermic circulatory arrest

Early experience with aprotinin in deep hypothermic circulatory arrest (DHCA) raised alarm about hazards associated with its use. Based on what little is known about possible mechanistic interactions between hypothermia, stasis, and aprotinin, there is no evidence that aprotinin becomes unusually hazardous in DHCA. Excessive mortality and complication rates have only been reported in clinical series in which the adequacy of heparinization is questionable. Benefits associated with use of aprotinin in DHCA have been inconsistently demonstrated. The only prospective, randomized series showed significant reduction in blood loss and transfusion requirements. Use of aprotinin in DHCA should be based on the same considerations applied in other cardiothoracic procedures.

Anti-fibrinolytic therapy in thoracic aortic surgery

BACKGROUND

Bleeding is an important cause of morbidity in thoracic aortic surgery.

METHODS

We reviewed the mechanisms for fibrinolysis in aortic surgery and the propensity for intervention. Several studies have addressed the safety and efficacy of aprotinin.

RESULTS

The endothelium regulates the balance between thrombosis and fibrinolysis. During hypothermic circulatory arrest, thrombin generation stimulates protein C production and tissue plasminogen activator release to promote fibrinolysis. Hypothermia also adversely affects platelet function and coagulation. Controversy exists regarding the effectiveness and dangers of antifibrinolytic agents after circulatory arrest.

CONCLUSIONS

Fibrinolysis remains problematic during thoracic aortic aneurysm surgery. Heparin management is complicated by aprotinin and insufficient heparin may result in thrombotic events. Aprotinin is safe during rewarming or postoperatively.

The efficacy and safety of aprotinin use in cardiac surgery

BACKGROUND

The serine protease inhibitor aprotinin has received much attention in cardiac surgical practice as a pharmacologic intervention to improve the hemostatic derangement associated with cardiopulmonary bypass. This review highlights the major studies undertaken to investigate the efficacy and safety of aprotinin use in both primary and repeat coronary artery bypass graft surgical procedures.

METHODS

There have been at least 45 controlled studies in more than 7,000 patients in a variety of patient populations. These have ranged from primary coronary artery bypass graft and valve operations to complex reoperation procedures, including aortic arch reconstructions and thoracic organ transplantation. The recently completed International Multicenter Graft Patency Experience trial, the largest study to date, involved 870 patients at 13 international sites. The study examined the effects of aprotinin on graft patency, incidence of myocardial infarction, and blood loss in patients undergoing primary coronary artery bypass graft operations with cardiopulmonary bypass.

RESULTS

Twenty-one studies in approximately 5,000 patients undergoing primary coronary artery bypass graft or valve operations reported 33% to 66% reduction in blood loss with full-dose aprotinin therapy; 15 of the same studies reported significant reductions in transfusion requirements, ranging from 31% to 85%. The recently completed International Multicenter Graft Patency Experience study observed a significant reduction in thoracic-drainage volume of 43% (p < 0.0001) and a 49% (p < 0.001) reduction in the requirement for allogeneic blood transfusions. Aprotinin did not affect the occurrence of definite myocardial infarction (aprotinin, 2.9% versus placebo, 3.8%) or mortality (aprotinin, 1.4% versus placebo, 1.6%). There was no observed difference in the patency of internal mammary artery bypass grafts from all study sites in aprotinin- versus placebo-treated patients (aprotinin, 98.2% versus placebo, 98.0%).

CONCLUSIONS

Given the risks and costs associated with excessive bleeding and transfusions and the limited supply of banked blood, aprotinin represents an important and safe approach to blood conservation.