Prophylactic Use of Antifibrinolytics During Pediatric Cardiac Surgery With Cardiopulmonary Bypass on Postoperative Bleeding and Transfusion: A Systematic Review and Meta-Analysis

OBJECTIVES

To determine the effect of intraoperative antifibrinolytics, including tranexamic acid (TXA), aminocaproic acid (EACA), or aprotinin, on bleeding in children undergoing cardiac surgery with cardiopulmonary bypass (CPB).

DATA SOURCES

Relevant articles were systematically searched from Ovid MEDLINE, Ovid EMBASE, CINAHL, Cochrane Library, and Web of Science to November 15, 2021.

STUDY SELECTION

Abstracts were screened, and full texts were reviewed using predetermined inclusion and exclusion criteria using the Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guideline.

DATA EXTRACTION

A standardized data extraction tool was used.

DATA SYNTHESIS

Sixty-eight studies including 28,735 patients were analyzed. TXA compared with placebo resulted in a mean decrease in chest tube output of 9.1 mL/kg (95% CI, 6.0-12.3 mL/kg), I2 equals to 65.2%, p value of less than 0.001, platelet requirement of 2.9 mL/kg (95% CI, 0.1-5.8 mL/kg), I2 =72.5%, p value less than 0.001 and plasma requirement of 4.0 mL/kg (95% CI, 0.6-7.2 mL/kg), I2 equals to 94.5%, p value less than0.001. Aprotinin compared with placebo resulted in a mean decrease in chest tube output of 4.3 mL/kg (2.4-6.2 mL/kg), I2 equals to 66.3%, p value of less than 0.001, platelet transfusion of 4.6 mL/kg (95% CI, 0.6-8.6 mL/kg), I2 equals to 93.6%, p value of less than 0.001, and plasma transfusion of 7.7 mL/kg (95% CI, 2.1-13.2 mL/kg), I2 equals to 95.3%, p value of less than 0.001. EACA compared with placebo resulted in a mean decrease in chest tube output of 9.2 mL/kg (2.3-21.0 mL/kg), I2 equals to 96.4%, p value of less than 0.001, RBC transfusion of 7.2 mL/kg (95% CI, 2.4-12.1 mL/kg), I2 equals to 94.5%, p value equals to 0.002, and platelet transfusion of 10.7 mL/kg (95% CI, 2.9-18.5 mL/kg), I2 equals to 0%, p value of less than 0.001. No statistical difference was observed in chest tube output when TXA was compared with aprotinin. Subgroup analysis of cyanotic patients showed a significant decrease in chest tube output, platelet requirement, and plasma requirement for patients receiving aprotinin. Overall, the quality of evidence was moderate.

CONCLUSIONS

Antifibrinolytics are effective at decreasing blood loss and blood product requirement in children undergoing cardiac surgery with CPB although the quality of evidence is only moderate.

Efficacy and safety of aprotinin in paediatric cardiac surgery: A systematic review and meta-analysis

BACKGROUND

The relicensing of aprotinin in Europe and Canada has stimulated discussions on its usefulness in paediatric cardiac surgery.

OBJECTIVE

To systematically evaluate the available evidence on the efficacy and safety of aprotinin in paediatric cardiac surgery.

DESIGN

Systematic review of all randomised and observational studies comparing aprotinin with tranexamic acid, epsilon aminocaproic acid, placebo or no drug in paediatric cardiac surgery. Meta-analyses were performed on efficacy and safety outcomes.

DATA SOURCES

PubMed, Cochrane Central Register of Controlled Trials, Web of Science and Embase were searched from January 2000 to March 2021.

ELIGIBILITY CRITERIA

Studies that enrolled children under 18 years undergoing cardiac surgery with cardiopulmonary bypass.

RESULTS

Thirty-two studies enrolling a total of 63 894 paediatric cardiac procedures were included. Aprotinin significantly reduced total blood loss [mean difference -4.70 ml kg-1, 95% confidence interval (CI), -7.88 to -1.53; P = 0.004], postoperative transfusion requirements and the incidence of surgical re-exploration for bleeding [odds ratio (OR) 0.74, 95% CI, 0.56 to 0.97; P = 0.03]. Aprotinin had no effects on 30-day mortality (OR 1.02, 95% CI, 0.93 to 1.11; P = 0.73) and on other safety outcomes, except for the incidence of renal replacement therapy (RRT), which was significantly increased in patients given aprotinin (OR 1.29, 95% CI, 1.08 to 1.54; P = 0.006). Findings from observational and randomised controlled trials did not largely differ. A sub-group analysis in neonates showed that aprotinin significantly reduced packed red blood cell transfusions and the incidence of postoperative surgical re-exploration for bleeding and/or tamponade. When compared with lysine analogues, aprotinin was more effective at reducing bleeding and transfusion without increasing the risk of side effects.

CONCLUSION

This meta-analysis suggests that aprotinin is effective and well tolerated in paediatric cardiac surgery. Given the large heterogeneity of the results and the risk of selection bias in observational studies, large randomised controlled trials are warranted.

Antifibrinolytic Drugs for the Prevention of Bleeding in Pediatric Cardiac Surgery on Cardiopulmonary Bypass: A Systematic Review and Meta-analysis

BACKGROUND

Bleeding is one of the commonest complications affecting children undergoing cardiac surgery on cardiopulmonary bypass. Antifibrinolytic drugs are part of a multifaceted approach aimed at reducing bleeding, though sufficiently sized pediatric studies are sparse, and dosing algorithms are heterogeneous. Our objective was to evaluate the efficacy and safety of antifibrinolytic agents as well as the effectiveness of different dosing regimens in pediatric cardiac surgery using cardiopulmonary bypass.

METHODS

We performed a systematic review and meta-analysis evaluating randomized controlled trials published between 1980 and 2019, identified by searching the databases MEDLINE, EMBASE, PubMed, and CENTRAL. All studies investigating patients <18 years of age without underlying hematological disorders were included. The primary outcome was postoperative bleeding; secondary end points included blood product transfusion, mortality, and safety (thromboses, anaphylaxis, renal or neurological dysfunction, and seizures). Different dosing regimens were compared. Studies were dual appraised, outcomes were reported descriptively and, if appropriate, quantitatively using the Review Manager 5 (REVMAN 5) software (The Cochrane Collaboration).

RESULTS

Thirty of 209 articles were included, evaluating the following drugs versus control: aprotinin n = 14, tranexamic acid (TXA) n = 12, and epsilon-aminocaproic acid (EACA) n = 4. The number of participants per intervention group ranged from 11 to 100 (median, 25; interquartile range [IQR], 20.5) with a wide age span (mean, 13 days to 5.8 years) and weight range (mean, 3.1-26.3 kg). Methodological quality was low to moderate.All agents reduced mean 24-hour blood loss compared to control: aprotinin by 6.0 mL/kg (95% confidence interval [CI], -9.1 to -3.0; P = .0001), TXA by 9.0 mL/kg (95% CI, -11.3 to -6.8; P < .00001), and EACA by 10.5 mL/kg (95% CI, -21.1 to 0.0; P = .05). Heterogeneity was low for TXA (I2 = 29%; P = .19), moderate for aprotinin (I2 = 41%; P = .11), and high for EACA (I2 = 95%; P = <.00001). All agents also reduced 24-hour blood product transfusion. There was no clear dose-response effect for TXA nor aprotinin. Studies were underpowered to detect significant differences in mortality, thromboses, anaphylaxis, and renal or neurological dysfunction.

CONCLUSIONS

The available data demonstrate efficacy for all 3 antifibrinolytic drugs. Therefore, the agent with the most favorable safety profile should be used. As sufficient data are lacking, large comparative trials are warranted to assess the relative safety and appropriate dosing regimens in pediatrics.

Enhanced Antifibrinolytic Efficacy of a Plasmin-Specific Kunitz-Inhibitor (60-Residue Y11T/L17R with C-Terminal IEK) of Human Tissue Factor Pathway Inhibitor Type-2 Domain1

Current antifibrinolytic agents reduce blood loss by inhibiting plasmin active sites (e.g., aprotinin) or by preventing plasminogen/tissue plasminogen activator (tPA) binding to fibrin clots (e.g., ε-aminocaproic acid and tranexamic acid); however, they have adverse side effects. Here, we expressed 60-residue (NH2NAE…IEKCOOH) Kunitz domain1 (KD1) mutants of human tissue factor pathway inhibitor type-2 that inhibit plasmin as well as plasminogen activation. A single (KD1-L17R-KCOOH) and a double mutant (KD1-Y11T/L17R- KCOOH) were expressed in Escherichia coli as His-tagged constructs, each with enterokinase cleavage sites. KD1-Y11T/L17R-KCOOH was also expressed in Pichia pastoris. KD1-Y11T/L17R-KCOOH inhibited plasmin comparably to aprotinin and bound to the kringle domains of plasminogen/plasmin and tPA with Kd of ~50 nM and ~35 nM, respectively. Importantly, compared to aprotinin, KD1-L17R-KCOOH and KD1-Y11T/L17R-KCOOH did not inhibit kallikrein. Moreover, the antifibrinolytic potential of KD1-Y11T/L17R-KCOOH was better than that of KD1-L17R-KCOOH and similar to that of aprotinin in plasma clot-lysis assays. In thromboelastography experiments, KD1-Y11T/L17R-KCOOH was shown to inhibit fibrinolysis in a dose dependent manner and was comparable to aprotinin at a higher concentration. Further, KD1-Y11T/L17R-KCOOH did not induce cytotoxicity in primary human endothelial cells or fibroblasts. We conclude that KD1-Y11T/L17R-KCOOH is comparable to aprotinin, the most potent known inhibitor of plasmin and can be produced in large amounts using Pichia.

A new anti-fibrinolytic hemostatic compound 8-O-acetyl shanzhiside methylester extracted from Lamiophlomis rotata

BACKGROUND

Fibrinolysis prevents blood clots from growing and becoming problematic. Antifibrinolytics are used as inhibitors of fibrinolysis. Aprotinin was doubted after identification of major side effects, especially on kidney. Lysine analogues has their own defects and whether they are adequate substitutes for aprotinin is still under doubt. Lamiophlomis rotata (Benth.) Kudo. was previous found to have hemostatic activity. But the active compound in L. rotata and its hemostatic mechanism were unknown.

OBJECTIVES

To find the major hemostatic compound in L. rotata and identify its haemostasis mechanism.

METHODS

Traumatic hemorrhage model and coagulant activity assays were monitored in mice and platelets in drug treatment group and control group. Hyperfibrinolysis model was established by intravenous administration of urokinase in mice. Capillary blood clotting time (CBCT), activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), fibrinogen and euglobulin clot lysis time (ECLT) were measured.

RESULTS

The anti-fibrinolytic activity come from 8-O-Acetyl shanzhiside methylester (ASM) one of the highest iridoid glycosides contents in TIG extracted from L. rotata. ASM significantly (P<0.05) shorten CBCT and reduced blood loss volume in vivo, but did not influence mice APTT, PT or TT. In particular, it significantly prolonged ECLT in hyperfibrinolysis mice. It indicated that ASM could inhibit fibrinolysis. ASM was also effective in CBCT, traumatic bleeding volume and ECLT in hyperfibrinolysis mice model.

CONCLUSIONS

ASM was the major hemostatic compound in L. rotata. The haemostasis mechanism of ASM was achieved by anti-fibrinolytic activity. ASM was a new fibrinolysis inhibitor as iridoid glycoside compound.

Augmentation of thrombin generation in neonates undergoing cardiopulmonary bypass

INTRODUCTION

Factor concentrates are currently available and becoming increasingly used off-label for treatment of bleeding. We compared recombinant activated factor VII (rFVIIa) with three-factor prothrombin complex concentrate (3F-PCC) for the ability to augment thrombin generation (TG) in neonatal plasma after cardiopulmonary bypass (CPB). First, we used a computer-simulated coagulation model to assess the impact of rFVIIa and 3F-PCC, and then performed similar measurements ex vivo using plasma from neonates undergoing CPB.

METHODS

Simulated TG was computed according to the coagulation factor levels from umbilical cord plasma and the therapeutic levels of rFVIIa, 3F-PCC, or both. Subsequently, 11 neonates undergoing cardiac surgery were enrolled. Two blood samples were obtained from each neonate: pre-CPB and post-CPB after platelet and cryoprecipitate transfusion. The post-CPB products sample was divided into control (no treatment), control plus rFVIIa (60 nM), and control plus 3F-PCC (0.3 IU ml(-1)) aliquots. Three parameters of TG were measured ex vivo.

RESULTS

The computer-simulated post-CPB model demonstrated that rFVIIa failed to substantially improve lag time, TG rate and peak thrombin without supplementing prothrombin. Ex vivo data showed that addition of rFVIIa post-CPB significantly shortened lag time; however, rate and peak were not statistically significantly improved. Conversely, 3F-PCC improved all TG parameters in parallel with increased prothrombin levels in both simulated and ex vivo post-CPB samples.

CONCLUSIONS

Our data highlight the importance of prothrombin replacement in restoring TG. Despite a low content of FVII, 3F-PCC exerts potent procoagulant activity compared with rFVIIa ex vivo. Further clinical evaluation regarding the efficacy and safety of 3F-PCC is warranted.

Antifibrinolytic agents in current anaesthetic practice

Antifibrinolytic drugs have become almost ubiquitous in their use during major surgery when bleeding is expected or commonplace. Inhibition of the fibrinolytic pathway after tissue injury has been consistently shown to reduce postoperative or traumatic bleeding. There is also some evidence for a reduction of perioperative blood transfusion. However, evidence of complications associated with exaggerated thrombosis also exists, although this appears to be influenced by the choice of the individual agent and the dose administered. There is controversy over the use of the serine protease inhibitor aprotinin, whose license was recently withdrawn but may shortly become available on the market again. In the UK, tranexamic acid, a tissue plasminogen and plasmin inhibitor, is most commonly used, with evidence for benefit in cardiac, orthopaedic, urological, gynaecological, and obstetric surgery. In the USA, ε-aminocaproic acid, which also inhibits plasmin, is commonly used. We have reviewed the current literature for this increasingly popular class of drugs to support clinical judgement in daily anaesthetic practice.

Aprotinin revisited

In 2008, we saw the withdrawal of aprotinin from the US markets after preliminary results from a large, randomized clinical trial in Canada. This drug, a potent antifibrinolytic, was used primarily in complex and/or redo cardiac surgery as an adjunct to decrease postoperative bleeding and complications. The Canadian study raised questions previously brought up in similar studies-does aprotinin increase the risk of mortality and renal failure after cardiac surgery? Recently, a re-review of the Canadian data noted flaws in the study, as well as in the interpretation of the results. The present review revisits the aprotinin controversy.

Aprotinin, transfusions, and kidney injury in neonates and infants undergoing cardiac surgery

BACKGROUND

A significantly increased risk of acute kidney injury (AKI) with the prophylactic use of aprotinin has been reported in adults undergoing cardiac surgery, but not in children. Blood product transfusions have also been shown to carry an independent risk of AKI. The present study assessed associations between AKI, aprotinin, and transfusions in neonates and infants undergoing cardiac surgery.

METHODS

All neonates and infants undergoing surgery with cardiopulmonary bypass over a 42 month period, before and after the withdrawal of aprotinin, were included retrospectively. AKI was assessed by the Acute-Kidney-Injury-Network classifications. A propensity score was used to balance treated and untreated groups.

RESULTS

Three hundred and ninety patients received aprotinin and 568 patients did not. Inverse probability of treatment weighting resulted in good balance between groups for baseline and surgical characteristics. Controls underwent surgery with smaller bypass circuits and fewer transfusions. After adjustment for the use of miniaturized circuits and for the year of surgery, no significant association between the incidence of AKI, dialysis, and aprotinin was noted. Red blood cell transfusions were associated with an increased risk of AKI and dialysis: odds ratios (ORs) 1.64 (1.12-2.41) and 2.07 (1.13-3.73), respectively; as were fresh frozen plasma transfusions, ORs 2.28 (1.68-3.09) and 3.11 (1.95-4.97), respectively. Platelet transfusions were associated with an increased risk of dialysis: OR 2.20 (1.21-4.01).

CONCLUSIONS

Blood product transfusions, but not the prophylactic use of aprotinin, are significantly associated with AKI after cardiac surgery in neonates and infants.