Aprotinin in perspective

Targeting Crucial Host Factors of SARS-CoV-2

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread worldwide since its first incidence in Wuhan, China, in December 2019. Although the case fatality rate of COVID-19 appears to be lower than that of SARS and Middle East respiratory syndrome (MERS), the higher transmissibility of SARS-CoV-2 has caused the total fatality to surpass other viral diseases, reaching more than 1 million globally as of October 6, 2020. The rate at which the disease is spreading calls for a therapy that is useful for treating a large population. Multiple intersecting viral and host factor targets involved in the life cycle of the virus are being explored. Because of the frequent mutations, many coronaviruses gain zoonotic potential, which is dependent on the presence of cell receptors and proteases, and therefore the targeting of the viral proteins has some drawbacks, as strain-specific drug resistance can occur. Moreover, the limited number of proteins in a virus makes the number of available targets small. Although SARS-CoV and SARS-CoV-2 share common mechanisms of entry and replication, there are substantial differences in viral proteins such as the spike (S) protein. In contrast, targeting cellular factors may result in a broader range of therapies, reducing the chances of developing drug resistance. In this Review, we discuss the role of primary host factors such as the cell receptor angiotensin-converting enzyme 2 (ACE2), cellular proteases of S protein priming, post-translational modifiers, kinases, inflammatory cells, and their pharmacological intervention in the infection of SARS-CoV-2 and related viruses.

Antifibrinolytic drugs for treating primary postpartum haemorrhage

BACKGROUND

Postpartum haemorrhage (PPH) - heaving bleeding within the first 24 hours after giving birth - is one of the main causes of death of women after childbirth. Antifibrinolytics, primarily tranexamic acid (TXA), have been shown to reduce bleeding in surgery and safely reduces mortality in trauma patients with bleeding without increasing the risk of adverse events.An earlier Cochrane review on treatments for primary PPH covered all the various available treatments - that review has now been split by types of treatment. This new review concentrates only on the use of antifibrinolytic drugs for treating primary PPH.

OBJECTIVES

To determine the effectiveness and safety of antifibrinolytic drugs for treating primary PPH.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (28 May 2017) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs), including cluster-randomised trials of antifibrinolytic drugs (aprotinin, TXA, epsilon-aminocaproic acid (EACA) and aminomethylbenzoic acid, administered by whatever route) for primary PPH in women.Participants in the trials were women after birth following a pregnancy of at least 24 weeks' gestation with a diagnosis of PPH, regardless of mode of birth (vaginal or caesarean section) or other aspects of third stage management.We have not included quasi-randomised trials, or cross-over studies. Studies reported as abstracts have not been included if there was insufficient information to allow assessment of risk of bias.In this review we only identified studies looking at TXA.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data from each study using an agreed form. We entered data into Review Manager software and checked for accuracy.For key review outcomes, we rated the quality of the evidence as 'high', 'moderate', 'low' or 'very low' according to the GRADE approach.

MAIN RESULTS

Three trials (20,412 women) met our inclusion criteria. Two trials (20,212 women) compared intravenous (IV) TXA with placebo or standard care and were conducted in acute hospital settings (labour ward, emergency department) (in high-, middle- and low-income countries).One other trial (involving 200 women) was conducted in Iran and compared IV TXA with rectal misoprostol, but did not report on any of this review's primary or GRADE outcomes. There were no trials that assessed EACA, aprotinin or aminomethylbenzoic acid.Standard care plus IV TXA for the treatment of primary PPH compared with placebo or standard care aloneTwo trials (20,212 women) assessed the effect of TXA for the treatment of primary PPH compared with placebo or standard care alone. The larger of these (The WOMAN trial) contributed over 99% of the data and was assessed as being at low risk of bias. The quality of the evidence varied for different outcomes, Overall, evidence was mainly graded as moderate to high quality.The data show that IV TXA reduces the risk of maternal death due to bleeding (risk ratio (RR) 0.81, 95% confidence interval (CI) 0.65 to 1.00; two trials, 20,172 women; quality of evidence: moderate). The quality of evidence was rated as moderate due to imprecision of effect estimate. The effect was more evident in women given treatment between one and three hours after giving birth with no apparent reduction when given after three hours (< one hour = RR 0.80, 95% CI 0.55 to 1.16; one to three hours = RR 0.60, 95% CI 0.41 to 0.88; > three hours = RR 1.07, 95% 0.76 to 1.51; test for subgroup differences: Chi² = 4.90, df = 2 (P = 0.09), I² = 59.2%). There was no heterogeneity in the effect by mode of birth (test for subgroup differences: Chi² = 0.01, df = 1 (P = 0.91), I² = 0%). There were fewer deaths from all causes in women receiving TXA, although the 95% CI for the effect estimate crosses the line of no effect (RR 0.88, 95% CI 0.74 to 1.05; two trials, 20,172 women, quality of evidence: moderate). Results from one trial with 151 women suggest that blood loss of ≥ 500 mL after randomisation may be reduced (RR 0.50, 95% CI 0.27 to 0.93; one trial, 151 women; quality of evidence: low). TXA did not reduce the risk of serious maternal morbidity (RR 0.99, 95% CI 0.83 to 1.19; one trial, 20,015 women; quality of evidence: high), hysterectomy to control bleeding (RR 0.95, 95% CI 0.81 to 1.12; one trial, 20,017 women; quality of evidence: high) receipt of blood transfusion (any) (RR 1.00, 95% CI 0.97 to 1.03; two trials, 20,167 women; quality of evidence: moderate) or maternal vascular occlusive events (any), although results were imprecise for this latter outcome (RR 0.88, 95% CI 0.54 to 1.43; one trial, 20,018 women; quality of evidence: moderate). There was an increase in the use of brace sutures in the TXA group (RR 1.19, 95% CI 1.01, 1.41) and a reduction in the need for laparotomy for bleeding (RR 0.64, 95% CI 0.49, 0.85).

AUTHORS' CONCLUSIONS

TXA when administered intravenously reduces mortality due to bleeding in women with primary PPH, irrespective of mode of birth, and without increasing the risk of thromboembolic events. Taken together with the reliable evidence of the effect of TXA in trauma patients, the evidence suggests that TXA is effective if given as early as possible.Facilities for IV administration may not be available in non-hospital settings therefore, alternative routes to IV administration need to be investigated.

Aprotinin Reduces Ischemia-Reperfusion Injury in the Retina of Guinea Pigs

Purpose

The aim of this study was investigate the role of aprotinin on retinal lipid peroxidation and histopathological changes during ischemia/reperfusion (I/R) of guinea pigs.

Methods

Three groups of seven pigmented guinea pigs each were formed: a control (group 1), ischemia/saline (group 2) and ischemia/aprotinin (group 3). One eye of each animal was selected for histopathological evaluation and the other for biochemical assay. Bilateral pressure-induced retinal ischemia was instigated for 90 min and was followed by 24 hours of reperfusion. Animals in the ischemia/aprotinin and ischemia/saline groups received either 20,000 KIU/kg of aprotinin or saline, repeated four times at 6-hour intervals, with the first dose administered 5 min prior to the ischemic insult. The animals were killed at 24 hours of reperfusion. Retinal malondialdehyde (MDA) levels and the thickness of the inner plexiform layers were measured.

Results

The level of MDA in group 1 was significantly (p<0.001) lower than the other groups. The mean MDA level in group 2 was significantly (p<0.01) higher than in group 3. The inner plexiform layer in group 1 was significantly (p<0.001) thinner than in the other groups. The mean thickness of the inner plexiform layer in group 2 was significantly (p<0.01) higher than in group 3.

Conclusions

These data indicate that intraperitoneally administrated aprotinin has a protective effect against I/R injury in the retina of guinea pig as evidenced by reduced retinal MDA level and retinal thickness.

Plasma Kallikrein Inhibitors in Cardiovascular Disease: An Innovative Therapeutic Approach

Plasma prekallikrein is the liver-derived precursor of the trypsin-like serine protease plasma kallikrein, and circulates in plasma bound to high molecular weight kininogen. Plasma prekallikrein is activated to plasma kallikrein by activated factor XII or prolylcarboxypeptidase. Plasma kallikrein regulates the activity of multiple proteolytic cascades in the cardiovascular system such as the intrinsic pathway of coagulation, the kallikrein-kinin system, the fibrinolytic system, the renin-angiotensin system, and the complement pathways. As such, plasma kallikrein plays a central role in the pathogenesis of thrombosis, inflammation, and blood pressure regulation. Under physiological conditions, plasma kallikrein serves as a cardioprotective enzyme. However, its increased plasma concentration or hyperactivity perpetuates cardiovascular disease (CVD). In this article, we review the biochemistry and cell biology of plasma kallikrein and summarize data from preclinical and clinical studies that have established important functions of this serine protease in CVD states. Finally, we propose plasma kallikrein inhibitors as a novel class of drugs with potential therapeutic applications in the treatment of CVDs.

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.

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.

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 versus tranexamic acid during liver transplantation: impact on blood product requirements and survival

BACKGROUND

Historically, orthotopic liver transplantation (OLT) has been associated with major blood loss and the need for blood product transfusions. Activation of the fibrinolytic system can contribute significantly to bleeding. Prophylactic administration of antifibrinolytic agents was found to reduce blood loss.

METHODS

The efficacy of two antifibrinolytic compounds--aprotinin (AP) and tranexamic acid (TA)--was compared in OLT. Four hundred consecutive OLTs were studied: 300 patients received AP and 100 received TA. Multivariate logistic regression analysis was used to identify independent predictors of intraoperative transfusion requirement and 1-year patient mortality.

RESULTS

There was no intergroup difference in intraoperative blood loss (1082±1056 vs. 1007±790 mL), red blood cell transfusion per patient (0.5±1.4 vs. 0.5±1.0), final hemoglobin (Hb) concentration (93±20 g/L vs. 95±22 g/L), the percentage of OLT cases requiring no blood product administration (80% vs. 82%), and 1-year survival (85.1% vs. 87.4%). Serum creatinine concentrations were also the same (116±55 vs. 119±36 μmol/L) 1 year after surgery. Two variables, starting Hb and phlebotomy, correlated with the two primary outcome measures (transfusion and 1-year survival).

CONCLUSIONS

In our experience, administration of AP was not superior to TA with regards to blood loss and blood product transfusion requirement during OLT. In addition, we found no difference between the groups in the 1-year survival rate and renal function. Furthermore, we suggest that starting Hb concentration should be considered when prioritizing patients on the waiting list and planning perioperative care for OLT recipients.

Heme oxygenase-1 induced by aprotinin inhibits vascular smooth muscle cell proliferation through cell cycle arrest in hypertensive rats

Spontaneous hypertensive rats (SHR) are an established model of genetic hypertension. Vascular smooth muscle cells (VSMC) from SHR proliferate faster than those of control rats (Wistar-Kyoto rats; WKY). We tested the hypothesis that induction of heme oxygenase (HO)-1 induced by aprotinin inhibits VSMC proliferation through cell cycle arrest in hypertensive rats. Aprotinin treatment inhibited VSMC proliferation in SHR more than in normotensive rats. These inhibitory effects were associated with cell cycle arrest in the G1 phase. Tin protoporphyrin IX (SnPPIX) reversed the anti-proliferative effect of aprotinin in VSMC from SHR. The level of cyclin D was higher in VSMC of SHR than those of WKY. Aprotinin treatment downregulated the cell cycle regulator, cyclin D, but upregulated the cyclin-dependent kinase inhibitor, p21, in VSMC of SHR. Aprotinin induced HO-1 in VSMC of SHR, but not in those of control rats. Furthermore, aprotinin-induced HO-1 inhibited VSMC proliferation of SHR. Consistently, VSMC proliferation in SHR was significantly inhibited by transfection with the HO-1 gene. These results indicate that induction of HO-1 by aprotinin inhibits VSMC proliferation through cell cycle arrest in hypertensive rats.

Pump Prime Aprotinin Fails to Limit Proinflammatory Cytokine Release After Coronary Artery Bypass Surgery

BACKGROUND

The purpose of this study was to establish whether pump prime aprotinin could limit the cytokine responses in patients undergoing elective coronary artery bypass surgery.

METHODS

Twenty-one patients admitted for first-time elective coronary artery bypass surgery were randomized into control or aprotinin groups. Patients in the aprotinin group received 280 mg aprotinin in the pump prime. Leukocyte count, creatine kinase cardiac isoenzyme (CK-MB), cytokine production and postoperative blood loss were analyzed perioperatively and compared with preoperative values.

RESULTS

The peak level of leukocyte count was lower in the aprotinin group than in controls (9.3 +/- 0.58 vs 11.2 +/- 0.68 x 10(9)/L, p = 0.01). Interleukin (IL)-6 and IL-8 did not differ significantly between the groups throughout the study period. Plasma IL-10 levels were higher in the controls than in the aprotinin group at 5 min (49.6 +/- 24.9 vs 8.13 +/- 2.8 pg/ml, p = 0.01) after reperfusion.

CONCLUSION

Pump prime aprotinin fails to limit proinflammatory cytokine response in circulating blood.

Aprotinin Inhibits Vascular Smooth Muscle Cell Inflammation and Proliferation via Induction of HO-1

Aprotinin is used clinically in cardiopulmonary bypass surgery to reduce transfusion requirements and the inflammatory response. The mechanism of action for the anti-inflammatory effects of aprotinin is still unclear. We examined our hypothesis whether inhibitory effects of aprotinin on cytokine-induced inducible nitric oxide synthase (iNOS) expression (IL-1beta plus TNF-alpha), reactive oxygen species (ROS) generation, and vascular smooth muscle cell (VSMC) proliferation were due to HO-1 induction in rat VSMCs. Aprotinin induced HO-1 protein expression in a dose-dependent manner, which was potentiated during inflammatory condition. Aprotinin reduced cytokine mixture (CM)-induced iNOS expression in a dose dependent manner. Furthermore, aprotinin reduced CM-induced ROS generation, cell proliferation, and phosphorylation of JNK but not of P38 and ERK1/2 kinases. Aprotinin effects were reversed by pre-treatment with the HO-1 inhibitor, tin protoporphyrin IX (SnPPIX). HO-1 is therefore closely involved in inflammatory-stimulated VSMC proliferation through the regulation of ROS generation and JNK phosphorylation. Our results suggest a new molecular basis for aprotinin anti-inflammatory properties.

Optimal dose of aprotinin for neuroprotection and renal function in a piglet survival model

OBJECTIVE

The efficacy of aprotinin in reducing blood loss after cardiopulmonary bypass is well established, although its neuroprotective potential is less well known. Furthermore, there is controversy regarding optimal dosing and possible renal complications.

METHODS

Fifty-four piglets were randomized to one of 3 cardiopulmonary bypass groups designed to carry the risk of postoperative cerebral and renal dysfunction: circulatory arrest at 25 degrees C and ultra-low flow bypass (10 mL x kg(-1) x min(-1)) at either 25 degrees C or 34 degrees C. Animals were randomized to the following groups: control (no aprotinin), low dose (30,000 KIU/kg into prime only), standard full dose (30,000 KIU/kg bolus administered intravenously into prime plus 10,000 KIU/kg infusion), and double full dose. The tissue oxygenation index was monitored by means of near-infrared spectroscopy. Neurologic functional and histologic scores and creatinine and blood urea nitrogen values were outcomes of interest.

RESULTS

Aprotinin significantly improved neurologic scores on postoperative day 1 after ultra-low-flow bypass at 25 degrees C or 34 degrees C (P < .01) but not after hypothermic circulatory arrest (P = .57). Linear regression indicated a strong dose-response relationship, with higher aprotinin doses having the best neurologic scores. During low-flow bypass, a higher tissue oxygenation index was correlated with a higher aprotinin dose (P < .05). Aprotinin dose had no significant effect on creatinine or blood urea nitrogen values on day 1. Low body weight was the only predictor of high blood urea nitrogen values (r = -0.39, P < .01).

CONCLUSION

Aprotinin significantly improves neurologic recovery without compromising renal function in the young piglet.

Assessment of aprotinin influence on periodontal clinical status and matrix metalloproteinases 1, 2 and their tissue inhibitors saliva concentrations in patients with chronic periodontitis

PURPOSE

Assessment of the effect of treatment with aprotinin-containing drug on the clinical status of the periodontal tissue and on the concentrations of metalloproteinases released in the course of periodontitis (MMP-1, MMP-2) as well as their tissue inhibitors (TIMP-1 and TIMP-2) in the saliva of patients with chronic periodontitis (CP).

MATERIAL/METHODS

The study involved 25 subjects with CP (39-68 years), including 16 women and 9 men. The patients were prescribed aprotinin preparation to be taken for 2 weeks. The control group (C) involved 14 healthy subjects (41-65 years), including 10 women and 4 men. Two periodontal indices were assessed: the approximal plaque index (API) and bleeding on probing index (BOP). Periodontal pocket depth and clinical attachment level were also evaluated. The concentrations of MMP-1 and MMP-2 as well as TIMP-1 and TIMP-2 were determined by the ELISA method.

RESULTS

The mean salivary MMP-1 concentration in patients with CP was significantly higher before and after treatment, as compared to healthy subjects. The mean salivary MMP-2 concentration in CP patients at baseline was also higher as compared to the C group and increased after treatment. The mean salivary TIMP-1 and TIMP-2 concentration in CP patients was higher as compared to C group and increased after treatment.

CONCLUSIONS

Since the mean MMPs levels were found to be growing it can be assumed that aprotinin has no significant effect on the regulation of MMPs in the saliva of CP patients. It thus seems that aprotinin application after scaling has no additional therapeutic effect.

A benefit-risk review of systemic haemostatic agents: part 1: in major surgery

Systemic haemostatic agents play an important role in the management of blood loss during major surgery where significant blood loss is likely and their use has increased in recent times as a consequence of demand for blood products outstripping supply and the risks associated with transfusions. Their main application is as prophylaxis to reduce bleeding in major surgery, including cardiac and orthopaedic surgery and orthotopic liver transplantation. Aprotinin has been the predominant agent used in this setting; of the other antifibrinolytic agents that have been studied, tranexamic acid is the most effective and epsilon-aminocaproic acid may also have a role. Eptacog alfa (recombinant factor VIIa) has also shown promise. Tranexamic acid, epsilon-aminocaproic acid and eptacog alfa are generally well tolerated; however, when considering the methods to reduce or prevent blood loss intra- and postoperatively, the benefits of these agents need to be weighed against the risk of adverse events. Recently, concerns have been raised about the safety of aprotinin after an association between increased renal dysfunction and mortality was shown in retrospective observational studies and an increase in all-cause mortality with aprotinin relative to tranexamic acid or epsilon-aminocaproic acid was seen after a pre-planned periodic analysis of the large BART (Blood conservation using Antifibrinolytics in a Randomized Trial) study. The latter finding resulted in the trial being halted, and aprotinin has subsequently been withdrawn from the market pending detailed analysis of efficacy and safety results from the study. Part 1 of this benefit-risk review examines the efficacy and adverse effect profiles of systemic haemostatic agents commonly used in surgery, and provides individual benefit-risk profiles that may assist clinicians in selecting appropriate pharmacological therapy in this setting.

Effects of Vitamin E, Pentoxifylline and Aprotinin on Light-Induced Retinal Injury

PURPOSE

A considerable amount of clinical and experimental evidence exists suggesting the involvement of reactive oxygen species (ROS) in the etiology of light-induced retinal injury. The aim of this study was to investigate the protective role of vitamin E, pentoxifylline (PTX) and aprotinin against light-induced retinal injury in guinea pigs.

METHODS

Thirty adult male guinea pigs were divided into 5 groups of 6 animals each. The first group was used as control. The guinea pigs were kept in cyclic light for 2 weeks before the experiments. The animals were maintained in 12-hour light-dark cycles, before and after exposure to intense white fluorescent light, for as long as 12 h and then returned to cyclic light. Groups 3-5 received intraperitoneal injections of vitamin E, PTX and aprotinin, respectively. One eye of each animal was selected for histopathological evaluation and the other for biochemical assay. Retinal malondialdehyde (MDA) levels and the thickness of the outer nuclear layers were measured.

RESULTS

The compounds had the following relationships: vitamin E more than PTX more than aprotinin in preventing light-induced retinal damage. All 3 gave significant protection against the formation of MDA. Retinas of all 3 treatment groups had been protected from light-induced injury.

CONCLUSION

The intraperitoneal vitamin E, PTX and aprotinin supplementations may strengthen the antioxidant defense system because of decreased ROS, and these agents may play a role in treating light-induced retinal injury.

Aprotinin attenuates the elevation of pulmonary vascular resistance after cardiopulmonary bypass

Pulmonary vascular resistance (PVR) is generally believed to be elevated after cardiopulmonary bypass (CPB) due to whole body inflammation. Aprotinin has an antiinflammatory action, and it was hypothesized that aprotinin would attenuate the PVR increase induced by CPB. Ten mongrel dogs were placed under moderately hypothermic CPB for 2 hr. The experimental animals were divided into a control group (n=5, group I) and an aprotinin group (n=5, group II). In group II, aprotinin was administered during pre-bypass (50,000 KIU/kg) and post-bypass (10,000 KIU/kg) periods. Additional aprotinin (50,000 KIU/kg) was mixed in CPB priming solution. PVRs at pre-bypass and post-bypass 0, 1, 2, 3 hr were calculated, and lung tissue was obtained after the experiment. Post-bypass PVRs were significantly higher than prebypass levels in all animals (n=10, p<0.001). PVR elevation in group II was less than in group I at 3 hr post-bypass (p=0.0047). Water content of the lung was lower in group II (74+/-9.4%) compared to that of group I (83+/-9.5%), but the difference did not reach significance (p=0.076). Pathological examination showed a near normal lung structure in group II, whereas various inflammatory reactions were observed in group I. We concluded that aprotinin may attenuate CPB-induced PVR elevation through its anti-inflammatory effect.

Effects of intraperitoneal vitamin E, melatonin and aprotinin on leptin expression in the guinea pig eye during experimental uveitis

PURPOSE

To observe ultrastructural changes and leptin expression in the guinea pig eye during experimental uveitis (EU) and the effects of vitamin E, melatonin and aprotinin on leptin expression.

METHODS

Thirty male guinea pigs were randomly classified into five groups. Group 1 was the control group. Groups 2, 3, 4 and 5 received intravitreal injections of bovine serum albumin (BSA) to induce EU. At the same time on the third day, groups 3 (EU + vitamin E), 4 (EU + melatonin) and 5 (EU + aprotinin) received intraperitoneal vitamin E (150 mg/kg), melatonin (10 mg/kg) and aprotinin (20,000 IU/kg), respectively. On the sixth day, histopathological and clinical scoring of inflammation were performed, and leptin expression was investigated in the retina, choroid, sclera, episclera and cornea, and compared.

RESULTS

There was a remarkable increase in leptin expression in the retina, choroid, sclera and episclera in the EU group. Leptin expression in the treatment groups was similar to that in the control group. At light and electron microscopic levels, ganglion cells were oedematous and inner plexiform layer thickness had increased in the EU group retinas. Oedema was decreased in the treatment groups. Comparison of the EU and treatment groups revealed significant differences histopathologically and clinically.

CONCLUSION

Experimental uveitis causes an increase in leptin expression in the retina, choroid, sclera and episclera of guinea pigs. Vitamin E, melatonin and aprotinin inhibit this increase. Leptin seems to be closely related to ocular inflammation.

The effect of aprotinin in a model of uncontrolled hemorrhagic shock

BACKGROUND

Aprotinin has been shown to promote clot formation through its antifibrinolytic activity, by inhibiting the plasmin-induced complement activation and by protecting the platelets adhesive surface receptors. It has been successfully used in cardiac and liver transplantation surgery.

OBJECTIVE

To evaluate the effect of aprotinin in a model of uncontrolled intra-abdominal bleeding as a basis for its potential use in trauma patients.

METHODS

Twenty rats were randomly divided into 2 groups. All animals were operated on and bleeding was induced by transecting 1 lobe of the liver. In the treatment group a single dose of 30,000 U/kg of aprotinin was administered 5 minutes after the injury. The animals were monitored for hemodynamic parameters, blood loss volume, and mortality rates.

RESULTS

At 120 minutes from trauma induction a significant difference in mean blood pressure was observed: 67+/-22 mm Hg in the treatment group versus 53+/-28 mm Hg in the control group (P=.04). This difference remained consistent until the end of the experiment. Treatment with aprotinin also resulted in a tendency to an increased survival rate (P=.05) and increased mean survival time: 175+/-46 minutes as compared to 123+/-48 minutes in the controls (P=.027).

CONCLUSIONS

Early administration of aprotinin resulted in temporary hemodynamic stabilization and prolonged survival in a model of uncontrolled bleeding. Further studies are needed to establish the possible use of aprotinin in the treatment of trauma patients.

The cerebroprotective effects of pentoxifylline and aprotinin during cardiopulmonary bypass in dogs

OBJECTIVE

The purpose of this study was to investigate the cerebroprotective effects of pentoxifylline (PNX) and aprotinin in dogs using cardiopulmonary bypass (CPB).

MATERIALS AND METHODS

Eighteen clinically healthy dogs were divided into three groups: Group 1 (control, n = 6), Group 2 (PNX, n = 6), and Group 3 (aprotinin, n = 6). PNX was administered at a dose of 300 mg/day in Group 2 three days before the operation and during the operation. Half a million IU aprotinin were added to the prime solution and 500,000 IU were transfused via a central venous jugular catheter preoperatively in Group 3. Blood samples were taken from the central jugular vein before and after CPB and interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and S100beta protein were measured. Gliosis was investigated histopathologically in cerebral cortex biopsy samples under light microscopy.

RESULTS

The preoperative results of IL-6, TNF-alpha, and S100beta protein values were found to be significantly higher (p < 0.001) when compared with postoperative values. This significant difference was observed in the same parameters between Groups 1 and 2, and 1 and 3 (p < 0.001). There was no significant difference between Groups 2 and 3. Comparison between pre- and postoperative levels of IL-6 and TNF-alpha for Group 2 and Group 3 revealed statistically significant differences (p < 0.001), whereas S100beta protein levels did not. Histopathological examinations showed significant differences between the control group and PNX and aprotinin, and between aprotinin and PNX groups (p < 0.001).

CONCLUSION

PNX and aprotinin might be useful in order to reduce postoperative cerebral damage in patients undergoing cardiac surgery with CPB.

Which may be effective to reduce blood loss after cardiac operations in cyanotic children: tranexamic acid, aprotinin or a combination?

BACKGROUND

Children with cyanotic heart disease undergoing cardiac surgery in which cardiopulmonary bypass is used are at increased risk of postoperative bleeding. In this study, the authors investigated the possibility of reducing postoperative blood loss by using aprotinin and tranexamic acid alone or a combination of these two agents.

METHODS

In a prospective, randomized, blind study, 100 children undergoing cardiac surgery were investigated. In group 1 (n = 25) patients acted as the control and did not receive either study drugs. In group 2 (n = 25) patients received aprotinin (30.000 KIU.kg(-1) after induction of anesthesia, 30.000 KIU.kg(-1) in the pump prime and 30.000 KIU.kg(-1) after weaning from bypass). In group 3 (n = 25) patients received tranexamic acid (100 mg.kg(-1) after induction of anesthesia, 100 mg.kg(-1) in the pump prime and 100 mg.kg(-1) after weaning from bypass). In group 4 (n = 25) patients received a combination of the two agents in the same manner. Total blood loss and transfusion requirements during the period from protamine administration until 24 h after admission to the intensive care unit were recorded. In addition, hemoglobin, platelet counts and coagulation studies were recorded.

RESULTS

Postoperative blood loss was significantly higher in the control group (group 1) compared with children in other groups who were treated with aprotinin, tranexamic acid or a combination of the two agents (groups 2, 3 and 4) during the first 24 h after admission to cardiac intensive care unit (40 +/- 18 ml.kg(-1).24 h(-1), aprotinin; 35 +/- 16 ml.kg(-1).24 h(-1), tranexamic acid; 34 +/- 19 ml.kg(-1).24 h(-1), combination; 35 +/- 15 ml.kg(-1).24 h(-1)). The total transfusion requirements were also significantly less in the all treatment groups. Time taken for sternal closure was longer in the control group (68 +/- 11 min) compared with treatment groups 2, 3 and 4, respectively (40 +/- 18, 42 +/- 11, 42 +/- 13 min, P < 0.05). The coagulation parameters were not found to be significantly different between the three groups.

CONCLUSIONS

Our results suggested that both agents were effective to reduce postoperative blood loss and transfusion requirements in patients with cyanotic congenital heart disease. However, the combination of aprotinin and tranexamic acid did not seem more effective than either of the two drugs alone.

Avoidance of Bleeding During Surgery in Patients Receiving Anticoagulant and/or Antiplatelet Therapy

Perioperative management of chronically anticoagulated patients and/or patients treated with antiplatelet therapy is a complex medical problem. This review considers the pharmacokinetic and pharmacodynamic properties of commonly used antiplatelet and anticoagulant drugs with special emphasis on loss of effects after discontinuation and possible counteracting (or antidote) strategies. These drugs are aspirin (acetylsalicylic acid), ticlopidine/clopidogrel, abciximab, tirofiban and eptifibatide, heparin (unfractionated and low-molecular-weight), warfarin and direct thrombin inhibitors. Since the pharmacological mechanisms of some of these drugs are based on irreversible or slowly reversible effects, their pharmacokinetic profiles are not necessarily predictive for their pharmacodynamic profiles. A close and direct relationship between plasma concentrations and effects is seen only for the glycoprotein (GP) IIb/IIIa inhibitors tirofiban and eptifibatide with a fast off-rate for dissociation from the GPIIb/IIIa receptor, and for direct thrombin inhibitors (hirudin and argatroban). For other compounds, drug concentrations in plasma and pharmacodynamic effects are not closely correlated because of, for example, irreversible binding to their target (aspirin, clopidogrel and abciximab), inhibition of the generation of a subset of clotting factors with differing regeneration and degradation rates (coumarins) or sustained binding to the vascular wall (heparins). Surgery in patients on anticoagulant and/or antiplatelet therapy may be categorised as: (i) elective versus urgent; and (ii) cardiopulmonary bypass (CPB) versus non-CPB. Monotherapy with clopidogrel or aspirin need not be discontinued in elective non-CPB surgery, and temporary discontinuation of warfarin should be accompanied by preoperative intravenous heparin only in selected high-risk patients. Vitamin K as an antidote for warfarin should only be used subcutaneously and solely in urgent/emergency surgery. In elective surgery requiring CPB (coronary artery bypass grafting), it is recommended to discontinue aspirin 7 days preoperatively in patients with a low risk profile. Patients requiring urgent CPB surgery (e.g. after failure of a percutaneous coronary angioplasty with or without coronary stent deployment) are usually pretreated with several antiplatelet agents (e.g. aspirin and clopidogrel, together with a GPIIb/IIIa inhibitor) together with unfractionated or low-molecular-weight heparin. With judicious planning, urgent/emergency cardiac surgery can be safely performed on these patients. Delaying surgery (e.g. for 12 hours in patients treated with abciximab) should be considered if possible. Standard heparin doses should be given to achieve optimal anticoagulation for CPB. Prophylactic use of aprotinin (intra- and/or postoperatively), aminocaproic acid or tranexamic acid should be considered. Early (in the operating theatre prior to chest closure) and judicious use of replacement blood products (platelets) should be commenced when clinically indicated.

Pharmacological strategies to decrease transfusion requirements in patients undergoing surgery

Surgical procedures are inevitably associated with bleeding. The amount of blood loss may vary widely between different surgical procedures and depends on surgical as well as non-surgical factors. Whereas adequate surgical haemostasis may suffice in most patients, pro-haemostatic pharmacological agents may be of additional benefit in patients with (diffuse) surgical bleeding or in patients with a specific underlying haemostatic defect. In general, surgical haemostasis and pharmacological therapies can be complementary in controlling blood loss. The use of pharmacological therapies to reduce blood loss and blood transfusions in surgery has historically been restricted to a few drugs. Antifibrinolytic agents (aprotinin, tranexamic acid and aminocaproic acid) have the best evidence supporting their use, especially in cardiac surgery, liver transplantation and some orthopaedic surgical procedures. Meta-analyses of randomised, controlled trials in cardiac patients have suggested a slight benefit of aprotinin, compared with the other antifibrinolytics. Desmopressin is the treatment of choice in patients with mild haemophilia A and von Willebrand disease. It has also been shown to be effective in patients undergoing cardiac surgery who received aspirin up to the time of operation. However, overall evidence does not support a beneficial effect of desmopressin in patients without pre-existing coagulopathy undergoing elective surgical procedures. Topical agents, such as fibrin sealants have been successfully used in a variety of surgical procedures. However, only very few controlled clinical trials have been performed and scientific evidence supporting their use is still limited. Novel drugs, like recombinant factor VIIa (eptacog alfa), are currently under clinical investigation. Recombinant factor VIIa has been introduced for the treatment of haemophilia patients with inhibitors, either in surgical or non-surgical situations. Preliminary data indicate that it may also be effective in surgical patients without pre-existing coagulation abnormalities. More clinical trials are warranted before definitive conclusions can be drawn about the safety and the exact role of this new drug in surgical patients. Only adequately powered and properly designed randomised, clinical trials will allow us to define the most effective and the safest pharmacological therapies for reducing blood loss and transfusion requirements in surgical patients. Future trials should also consider cost-effectiveness because of considerable differences in the costs of the available pro-haemostatic pharmacological agents.

Bacterial Lipopolysaccharide-Stimulated Release of Tumor Necrosis Factor-α from the Isolated Rat Heart: The Effect of Aprotinin and Forskolin

Aprotinin has been reported to reduce plasma levels of inflammatory cytokines associated with cardiopulmonary bypass (CPB). Because CPB is also associated with elevated levels of bacterial lipopolysaccharide (LPS) and LPS stimulates release of inflammatory cytokines from the heart we tested the hypothesis that aprotinin would inhibit cardiac release of tumor necrosis factor-α (TNF) provoked by LPS. Isolated rat hearts were perfused Langendorf style. After 30 minutes of equilibration LPS (100 ng/mL) was infused for 60 minutes. Timed samples of coronary effluent were collected at 0, 30, 60, 90, 120, and 150 minutes after the initiation of LPS for the measurement of coronary flow and the determination of TNF and cyclic AMP. Other hearts were perfused with buffer containing aprotinin [137 kallikrein-inhibiting units (KIU)/mL or 250 KIU/mL] and then infused with LPS. An additional group received forskolin (10 μM) and LPS. In hearts perfused as controls with buffer alone no TNF was detected in the coronary effluent. In hearts perfused with LPS TNF was reliably detected in the coronary effluent at 60 minutes (606 ± 450 pg/min) and increased with time to a level of 1792 ± 650 pg/min at 150 minutes. The addition of aprotinin had no significant effect on LPS-stimulated TNF release. For instance in hearts perfused with 137 KIU/mL aprotinin LPS-stimulated release at 150 minutes was 2141 ± 732 pg/min and in hearts perfused with 250 KIU/mL LPS-stimulated TNF release was 2049 ± 789 pg/min. Forskolin administration was associated with release of cyclic AMP from the heart and completely inhibited LPS-stimulated TNF release. We conclude that LPS stimulated release of TNF from the heart. Adding aprotinin to the perfusion buffer in either high or low concentrations did not attenuate LPS-stimulated cytokine release. Elevating myocardial cyclic AMP with forskolin completely attenuated LPS-stimulated TNF release.

Does aprotinin influence the inflammatory response to cardiopulmonary bypass in patients?

OBJECTIVES

Aprotinin has been shown to have anti-inflammatory properties, but its effects on the inflammatory reaction to cardiopulmonary bypass remain controversial. This prospective, randomized, double-blind study evaluated the influence of aprotinin on various blood markers of inflammation during and after cardiopulmonary bypass.

METHODS

Sixty male patients underwent coronary artery bypass grafting. The patients were randomized into 3 groups: a placebo group, a second group receiving 2,000,000 KIU of aprotinin followed by an infusion of 500,000 KIU/h and 2,000,000 KIU in the pump prime, and a third group receiving half this dosage. Measurements of tumor necrosis factor, interleukin 6, interleukin 8, interleukin 10, endotoxin, histamine, complement factors, prekallikrein, and prostaglandin D(2) were obtained at baseline, 30 minutes after study drug loading, 10 minutes after the beginning of cardiopulmonary bypass, before the end of bypass, 4 hours after bypass, and on the first and second postoperative days.

RESULTS

Aprotinin had no significant effect on any of these parameters. As expected, aprotinin reduced early blood loss in both treated groups.

CONCLUSIONS

These results indicate that aprotinin at doses currently used to reduce blood loss has no significant influence on the systemic inflammatory response during moderate hypothermic cardiopulmonary bypass in human subjects, as assessed by the mediators measured in this study.

Pharmacotherapeutic considerations in anesthesia

This article focuses on new findings leading to improved understanding of the pathophysiology and mechanisms of potential drug interactions between anesthetic drugs or techniques and cardiovascular medications in patients scheduled for surgery. Only the most frequently used drugs are reviewed. Elective surgery provides the luxury to consider these risks and alter therapy accordingly. Under urgent circumstances, however, the increased risks associated with these agents should be anticipated with the goal to minimize adverse effects while maintaining optimal cardiovascular function in the perioperative period.

Soluble adhesion molecules in coronary surgery and cardiopulmonary bypass with pump prime aprotinin

OBJECTIVE

The purpose of the present study was to establish whether pump prime aprotinin could influence soluble adhesion molecules in patients undergoing elective coronary artery bypass surgery.

DESIGN

Thirty patients admitted for first-time elective coronary artery bypass surgery were randomized into control or aprotinin groups. Patients in the aprotinin group received 280 mg of aprotinin in the pump prime. Plasma levels of soluble adhesion molecules were analyzed perioperatively.

RESULTS

There were no significant changes in plasma sE-selectin after the operation in either group. Plasma sP-selectin increased significantly up to 20 h after reperfusion to the myocardium. Plasma sICAM-1 decreased in the early stage after cardiopulmonary bypass (CPB), then recovered at 4 h after reperfusion and a significant increase in sICAM-1 was observed 20 h later. There were no significant differences between the groups in postoperative changes in sP-selectin (p = 0.21) and sICAM-1 (p = 0.91).

CONCLUSION

Pump prime aprotinin did not influence plasma levels of E-selectin, P-selectin and ICAM-1 in the present patients. The present results do not support the concept of an anti-inflammatory effect of pump prime aprotinin.

A family of textilinin genes, two of which encode proteins with antihaemorrhagic properties

Two peptides, textilinins 1 and 2, isolated from the venom of the Australian common brown snake, Pseudonaja textilis textilis, are effective in preventing blood loss. To further investigate the potential of textilinins as antihaemorrhagic agents, we cloned cDNAs encoding these proteins. The isolated full-length cDNA (430 bp in size) was shown to code for a 59 amino acid protein, corresponding in size to the native peptide, plus an additional 24 amino acid propeptide. Six such cDNAs were identified, differing in nucleotide sequence in the coding region but with an identical propeptide. All six sequences predicted peptides containing six conserved cysteines common to Kunitz-type serine protease inhibitors. When expressed as glutathione S-transferase (GST) fusion proteins and released by cleavage with thrombin, only those peptides corresponding to textilinin 1 and 2 were active in inhibiting plasmin with Ki values similar to those of their native counterparts and in binding to plasmin less tightly than aprotinin by two orders of magnitude. Similarly, in the mouse tail vein blood loss model only recombinant textilinin 1 and 2 were effective in reducing blood loss. These recombinant textilinins have potential as therapeutic agents for reducing blood loss in humans, obviating the need for reliance on aprotinin, a bovine product with possible risk of transmissible disease, and compromising the fibrinolytic system in a less irreversible manner.

A combined approach for improving cardiopulmonary bypass in coronary artery surgery: a pilot study

BACKGROUND

This is a pilot study carried out to assess the feasibility and the clinical impact of a combined approach of cardiopulmonary bypass (CPB) with reduced anti-coagulation.

METHODS

We used a retrospective, non-randomized analysis of 45 consecutive patients undergoing coronary artery bypass using standard CPB with full anticoagulation (activated clotting time, ACT, > 450 s) (Group 1; n = 23) or closed, heparin-coated CPB with low anticoagulation (ACT>250 s), precise heparin and protamine titration, controlled suction, and retrograde autologous prime (Group 2; n = 22).

RESULTS

Patients were similar except for a higher incidence of three-vessel disease in Group 2 (77.3% versus 47.8%; p < 0.03). Heparin was reduced by 41% in Group 2 and protamine by 56% (p < 0.0001). Total postoperative blood loss was similar between Groups 1 and 2 (429 +/- 149 versus 435+/-168 ml, respectively). However, the operative hematocrit decrease was lower in Group 2 (-1.6 +/- 7.5% versus -6.9 +/- 4.8%; p = 0.007), although hemodilution was similar, as reflected by the blood protein level. The need for postoperative inotropic support was less frequent in Group 2 (36.4% versus 65.2%; p = 0.05). Within the subgroup of patients weaned from CPB without requiring inotropic support (n = 35), the cardiac index dropped significantly in Group 1 (p = 0.003) 6 h after the start of CPB, whereas it remained stable in Group 2 (p = 0.92). Using multivariate analyses, Group 2 was found to be more protected than Group 1 against myocardial cellular injury (p = 0.046) and need for postoperative inotropic support (p = 0.014).

CONCLUSION

The pejorative postoperative outcome in coronary artery surgery was attenuated through a combined approach aimed at improving CPB.

Factor V(LEIDEN) and cardiopulmonary bypass: investigation of haemostatic parameters and the effect of aprotinin using an ex vivo model

It has been suggested that aprotinin results in significantly increased risk for perioperative thrombotic complications in patients with Factor V(LEIDEN) (F5L) due to its ability to competitively inhibit activated protein C (APC) function in vitro. No clinical studies have been performed to assess the effect of aprotinin on APC function of F5L in vivo. We developed an ex vivo model to mimic the effects of cardiopulmonary bypass with the exclusion of the patient in order to assess APC function. Blood from normal (n = 2) and F5L heterozygous donors (n = 2) was treated with aprotinin or placebo (saline). The blood was heparinized, added to the prime and circulated at 2 l/min through a modified cardiopulmonary bypass circuit. After 60 min of circulation, the heparin was neutralized with protamine sulfate. Blood samples, drawn at specific time points, were analysed for APC ratio. Results showed a decrease in APC ratio for both F5L and normal bloods with the addition of aprotinin (18% and 40%, respectively). APC ratios also decreased with the commencement of extracorporeal circulation for all bloods, resulting in an APC ratio of 1.35 in normal placebo-treated blood and 0.67 in F5L placebo-treated blood. The combined effect of aprotinin and extracorporeal circulation resulted in APC ratios of 0.90 for normal blood and 0.63 for F5L blood, corresponding to a severe dysfunction of APC intraoperatively (reference range 1.9-4.0). The data from this model predict an increased risk of perioperative thrombosis due to inhibition of APC function in cardiac surgical patients heterozygous for the F5L mutation. Aprotinin further compounds the severity of APC dysfunction, though the effect is more severe in normal blood. The ex vivo model employed was an effective tool for the investigation of the haemostatic effect of aprotinin. This model may be exploited for other applications such as the investigation of novel or emerging haemostatic agents prior to clinical trial.

Aprotinin and the systemic inflammatory response after cardiopulmonary bypass

Cardiopulmonary bypass is associated with a systemic inflammatory response, a spectrum of pathophysiologic changes ranging from mild organ dysfunction to multisystem organ failure. Complications include coagulation disorders (bleeding diathesis, hyperfibrinolysis) from platelet defects and plasmin activation, as well as pulmonary dysfunction from neutrophil sequestration and degranulation. Diverse injuries are a consequence of multiple inflammatory mediators (complement, kinins, kallikrein, cytokines). Both plasmin and kallikrein amplify the inflammatory response by activating components of the contact activation system. The full-Hammersmith (high dose) of aprotinin, a serine protease inhibitor approved for reducing blood loss and transfusion requirements in cardiopulmonary bypass, inhibits kallikrein and plasmin, resulting in suppression of multiple systems involved in the inflammatory response. Specifically, inhibition of factor XII, bradykinin, C5a, neutrophil integrin expression, elastase activity, and airway nitric oxide production are observed. Clinical correlates include reduced capillary leak, preserved systemic vascular resistance and blood pressure, and improved myocardial recovery following ischemia. Overall, evidence indicates that aprotinin attenuates the systemic inflammatory response associated with cardiopulmonary bypass.

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.

Does aprotinin reduce lung reperfusion damage after cardiopulmonary bypass?

OBJECTIVE

The role of aprotinin in the prevention of lung reperfusion injury was investigated in the patients undergoing cardio-pulmonary bypass (CPB) for coronary artery bypass grafting (CABG) operations.

METHODS

The study was planned randomly and prospectively. Two hundred milliliters of physiological saline solution was added to the prime solution of patients in group I (n=10) whereas, 200 ml aprotinin (Trasylol, Bayer AG) was given to patients in group II (n=10). In order to measure lung tissue malondialdehyde (MDA) levels, glutathion peroxidase (GSH-Px) activity levels and polymorphonuclear leukocytes (PMNs) numbers, lung tissue samples were taken before CPB and 5 min after removing the cross clamp. In addition, alveolo-arterial oxygen difference (AaDO(2)) for tissue oxygenation was calculated by obtaining arterial blood gas samples.

RESULTS

MDA levels before CPB increased from 41.72+/-21.00 nmol/g tissue to 66.71+/-13.44 nmol/g tissue in group I and from 43.44+/-5.16 nmol MDA/g tissue to 53.22+/-10.95 nmol MDA/g tissue in group II after cross clamp removal (P=0.001 and P=0.021, respectively). The increase in group II was found to be significantly lower than group I (P=0.048). With the initiation of reperfusion, GSH-Px activity decreased in group I from 3.05+/-0.97 to 2.31+/-0.46 U/mg protein (P=0.015) whereas GSH-Px activity in group II decreased from 3.18+/-1.01 to 2.74+/-0.81 U/mg protein (P=0. 055). This decrease in the group II was less than group I (P=0.049). AaDO(2) significantly increased in the group I and II (P=0.012 and P=0.020, respectively), but elevation in the group I was significant than in the Group II (P=0.049). In histopathological examination, it was observed that neutrophil counts in the lung parenchyma rose significantly following removal of cross clamp in both groups (P=0. 001). The increase in group I was significantly larger than in group II (P=0.050).

CONCLUSION

Results represented in our study indicate that addition of aprotinin (2 million units) into the prime solution during CPB can reduce lung reperfusion injury.

Aprotinin in ischemia-reperfusion injury: flap survival and neutrophil response in a rat skin flap model

Multiple drugs have been used in experimental skin flap models to reduce the effects of reperfusion ischemia. The effects of antiproteases, however, have not been studied. A skin flap ischemia reperfusion model was developed in the rat to study the effects that aprotinin, a broad-spectrum antiserine protease, would have on skin flap viability. Thirty-two male rats underwent elevation of a ventral pedicled skin flap based on the superficial inferior epigastric artery. The flaps were subjected to 10 hr of warm ischemia by clamping the neurovascular pedicle followed by reperfusion. Aprotinin or saline (control) was administered systemically via the contralateral femoral vein either before or after the ischemic insult. Full-thickness skin biopsies were obtained at 1, 8, and 24 hr into reperfusion. Biopsies were evaluated for neutrophil concentration (using a myeloperoxidase [MPO] assay) and thromboxane B2 [TxB2] content. Flap survival was calculated at 1 week using standardized photography and computer-assisted digital imaging. Aprotinin given before an ischemic insult significantly improved flap survival compared to saline controls (52.3% alive vs. 29.6%, P = 0.0132, unpaired t-test). Aprotinin given after ischemia did not significantly influence flap survival (28.8% vs. 34.4% in saline controls, P = 0.708). MPO levels in the aprotinin preischemia treatment group were significantly less at 1 and 8 hr into reperfusion, indicating decreased neutrophil numbers. No statistical difference in TxB2 levels was noted in either group at any time after reperfusion. Aprotinin significantly improves skin flap survival when given prior to but not after an ischemic insult. Aprotinin appears to lower the concentration of neutrophils in skin flaps pretreated with the drug. Reperfused skin flap levels of thromboxane B2 are unaffected by the pre- or postischemic administration of aprotinin.

Textilinins from Pseudonaja textilis textilis. Characterization of two plasmin inhibitors that reduce bleeding in an animal model

The incidence of vein-graft occlusion associated with myocardial infarction and thrombosis following the use of the plasmin inhibitor, aprotinin, to reduce blood loss during vascular surgery has prompted the isolation of an alternative kinetically distinct inhibitor of plasmin from the venom of Pseudonaja textilis. This inhibitor has been called textilinin (Txln) and two distinct forms have been isolated from the Brown-snake venom (molecular weight, 6688 and 6692). A comparison of plasmin inhibitor constants for aprotinin and the Txlns 1 and 2 indicated that the former bound very tightly (inhibitor constant, Ki approximately 10(-11) mol/l), while both of the latter bound less tightly (Ki approximately 10(-9) mol/l). Homogeneity of Txlns 1 and 2 was confirmed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and mass spectrometry. A sequence difference of six amino acids was observed between the two forms of Txln. Txln 1 and 2 showed, respectively, 45 and 43% homology with aprotinin, while there was 58 and 55% homology, respectively, with a plasmin inhibitor from the venom of eastern Taipan, Oxyuranus scutellatus. Both Txlns have six cysteines, like other inhibitors of this group, and homology was determined by alignment of these cysteines. Both have been shown to reduce blood loss by about 60% in a murine tail vein bleeding model. It is proposed that the kinetic profiles of Txln 1 and 2 for plasmin allow the arrest of haemorrhage without the possible threat of thrombosis.

Aprotinin in the management of life-threatening bleeding during extracorporeal life support

Contact with the synthetic surfaces of an extracorporeal circuit induces alterations in vascular components, derangements of the coagulation cascade and a systemic inflammatory response. Aprotinin reduces intraoperative and postoperative bleeding in adults undergoing cardiopulmonary bypass; however, trials in children have not had similar favorable results. While there have been some anecdotal reports, there have been no prospective clinical trials exploring the utility of aprotinin in the prevention of or as a therapy for bleeding while on extracorporeal life support (ECLS). We present a case series on our experience utilizing aprotinin for the treatment of life-threatening bleeding during ECLS. The combination of a loading dose followed by a continuous infusion resulted in significant reduction in blood loss and blood product utilization. This suggests that aprotinin may have clinical efficacy in the management of massive blood loss while on ECLS; however, larger controlled trials will be essential to determine the efficacy and appropriate dosing regimens before widespread use in ECLS can be advocated.

Aprotinin and transfusion requirements in orthotopic liver transplantation: a multicentre randomised double-blind study. EMSALT Study Group

BACKGROUND

Intraoperative hyperfibrinolysis contributes to bleeding during adult orthotopic liver transplantation. We aimed to find out whether aprotinin, a potent antifibrinolytic agent, reduces blood loss and transfusion requirements.

METHODS

We did a randomised, double-blind, placebo-controlled trial in which six liver-transplant centres participated. Patients undergoing primary liver transplantation were randomly assigned intraoperative high-dose aprotinin, regular-dose aprotinin, or placebo. Primary endpoints were intraoperative blood loss and transfusion requirements. Secondary endpoints were perioperative fluid requirements, postoperative blood transfusions, complications, and mortality.

FINDINGS

137 patients received high-dose aprotinin (n=46), regular-dose aprotinin (n=43), or placebo (n=48). Intraoperative blood loss was significantly lower in the aprotinin-treated patients, with a reduction of 60% in the high-dose group and 44% in the regular-dose group, compared with the placebo group (p=0.03). Total amount of red blood cell (homologous and autologous) transfusion requirements was 37% lower in the high-dose group and 20% lower in the regular-dose group, than in the placebo group (p=0.02). Thromboembolic events occurred in two patients in the high-dose group, none in the regular-dose group, and in two patients in the placebo group (p=0.39). Mortality at 30 days did not differ between the three groups (6.5%, 4.7%, and 8.3%; p=0.79).

INTERPRETATION

Intraoperative use of aprotinin in adult patients undergoing orthotopic liver transplantation significantly reduces blood-transfusion requirements and should be routinely used in patients without contraindications.

Aprotinin and tranexamic acid for high transfusion risk cardiac surgery

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Developing surgical intervention criteria for thoracic aortic aneurysms

In summary, the development of intervention criteria is a complex and challenging endeavor. Specific examination of this issue is crucial to the appropriate clinical care of patients. With these objectives in mind, we have drawn upon our clinical experience to design, by way of statistical analysis, reasoned size criteria for intervention. These intervention criteria must be carefully weighed against the patient's age, overall physical condition, and anticipated life expectancy. We have approached the development of criteria for intervention using statistical methodology from the standpoint of preventing complications (i.e., dissection and rupture). Symptomatic states, organ compression, concomitant aortic insufficiency, and acute ascending aortic dissection are well-accepted general indications for surgical intervention regardless of aortic size. The appendix incorporates the size criteria developed in the present study as an integral component within a comprehensive strategy for managing patients with TAA. This study confirms that aneurysms of the thoracic aorta are potentially lethal, that attentive follow-up is critical, and that adverse events can be anticipated based on size criteria. As we continue to expand our database, we hope to refine further statistically-based recommendations for surgical intervention. Multi-institutional patient enrollment, with the concomitant statistical power of larger patient numbers, would considerably strengthen this type of analysis.

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.