Prophylactic treatment of postperfusion bleeding using EACA

Immediate postoperative care of cardiac surgical patients

Anesthetic care of the cardiac surgery patient is a continuum, beginning with the preoperative visit and ending when the patient is ambulatory and breathing well on the postoperative floor. Anesthesiologists are well-suited to provide postoperative care because the respiratory and cardiovascular management techniques are an extension of OR management. Attention to details is as important in the ICU as in the OR and offers the opportunity to forestall or reduce morbidity.

Low-dose and high-dose aprotinin improve hemostasis in coronary operations

Prophylactic aprotinin therapy has become a popular method to reduce bleeding associated with cardiac operations. Today essentially two dose regimens are used, a high-dose regimen with administration throughout the complete operative procedure and a low-dose regimen with administration only during bypass. In unblinded studies both regimens were found to be equally effective. This double-blind placebo-controlled study in 115 patients undergoing elective coronary artery bypass grafting was done to confirm these results without potential investigator bias. Intraoperative hemoglobin loss was significantly reduced (p < 0.01) by 42% in the high-dose group and by 17% in the low-dose group compared with loss in control subjects. Blood loss 6 hours after operation was 377 ml in the low-dose and 266 ml in the high-dose group compared with 630 ml in the placebo group (p < 0.05 and p < 0.001, respectively). The average number of transfusions with packed red blood cells was reduced 31% in the low-dose group and 45% in the high-dose group, but the reductions were not significant. In a subgroup of patients, markers for coagulation and fibrinolysis were studied to investigate whether a different extent of activation existed. Fibrinolysis as measured by D-dimer levels was completely inhibited by the high-dose regimen, but was only partly suppressed in the low-dose group as compared with findings in the placebo group. Thrombin generation during cardiopulmonary bypass as reflected by F1 + 2 levels was lower in patients treated with aprotinin, but the difference was not significant. Concentrations of thrombin inactivated by antithrombin III were not different between the groups. The observation that low-dose aprotinin significantly improved hemostasis but did not inhibit hyperfibrinolysis supports our previous finding that low-dose aprotinin mainly protects platelet adhesive function. The better result obtained with high-dose aprotinin may indicate the contribution of hyperfibrinolysis to bleeding after cardiopulmonary bypass. Because high-dose aprotinin is administered outside the period of full heparinization and might therefore increase the risk of thromboembolic complications, we propose a modification of the low-dose schedule to increase aprotinin levels sufficient for plasmin inhibition before release of the aortic crossclamp.

Effect of aspirin-dipyridamole and heparin and their combination on venous thrombosis in hypercoagulable or thrombotic animals

Epsilon-amino-caproic acid (EACA) induces a clinically-useful anti-haemorrhagic, mildly thrombotic state while ellagic acid (EA) induces a severe hypercoagulable one. Reversal of these states may on occasion be necessary. The effectiveness of the antiplatelet drugs, aspirin and dipyridamole (ASA/D), in reducing thrombus weight was studied in normocoagulable animals and animals made hypercoagulable with EACA (333mg/kg) or EA (1.2mg/kg). Heparin (114iu/kg) was tested in the EACA group, both alone and in combination with ASA/D. Thrombogenicity was measured by weight formed on intravenous platinum wire in one hour. In normocoagulable animals, ASA/D reduced thrombus by 32%. Ellagic acid trebled mean thrombus weight and ASA/D reduced this by 49%, but did not restore normality. EACA increased mean thrombosis by one sixth. Treatment with heparin reduced this by 48% to a level well below that of untreated animals. Addition of a single dose of aspirin/dipyridamole to the heparin regime, reduced thrombosis by a further 31%, reaching to 21% of control thrombus. The results were statistically significant. Kaolin-activated blood clotting time was shortened by EA, but EACA had little effect on it, while ASA/D slightly and heparin markedly lengthened it.

The effect of low-dose epsilon-aminocaproic acid on patients following coronary artery bypass surgery

The effect of low-dose epsilon-aminocaproic acid (EACA) on the postoperative course of 46 patients was studied. Patients undergoing coronary artery bypass grafting were randomly selected in two groups. Group 1 (20 patients) received 5 g EACA upon initiation of cardiopulmonary bypass (CPB). Group 2 (26 patients) received no antifibrinolytic drugs prior to CPB. Neither group received antifibrinolytic drugs after CPB. There was no significant difference between the two groups' blood usage on CPB: 0.65 units in Group 1 and 0.60 units in Group 2. After CPB, blood usage significantly differed: 2.2 +/- 1.7 (SD) units in Group 1 and 3.9 +/- 3.0 units in Group 2 (p = 0.033). Significant difference was also demonstrated in postoperative blood loss in the first 24 hours: 1610 +/- 531 ml in Group 1 versus 2025 +/- 804 ml in Group 2 (p = 0.043). Pre-CPB administration of low-dose EACA significantly decreases blood loss and blood usage in the postoperative period.

Aprotinin prolongs whole blood activated partial thromboplastin time but not whole blood prothrombin time in patients undergoing cardiac surgery

Aprotinin is being used increasingly to limit cardiopulmonary bypass (CPB)-induced coagulation derangements. Since whole blood prothrombin time (PT) and activated partial thromboplastin time (APTT) assays are beneficial in the treatment of bleeding after CPB, we studied the potential effect of aprotinin on these whole blood assays. Blood specimens from 151 cardiac surgical patients were obtained in two phases: prior to heparin administration, before CPB, and subsequent to heparin neutralization after CPB. After collection, blood specimens were divided into two aliquots and mixed with either normal saline (NS) or aprotinin (A, 200 or 400 Kallikrein inhibiting units (KIU)/mL). Whole blood specimens were used to measure whole blood PT and APTT using CoaguChek Plus instruments. Whole blood PT results were similar between normal saline. (NS)- and aprotinin-spiked specimens before CPB (A, 12.9 +/- 1.5s; NS, 12.8 +/- 1.5s; P = 0.76) and after CPB (A, 17.5 +/- 2.4s; NS, 17.7 +/- 2.4s; P = 0.58). In contrast, whole blood APTT results were prolonged in aprotinin-spiked specimens prior to CPB (A, 63.3 +/- 32.2s; NS, 38.6 +/- 16.3s; P < 0.0001) and after CPB (A, 65.9 +/- 23.7s; NS, 45.7 +/- 14.4s; P < 0.0001). A dose-dependent prolongation of whole blood APTT by aprotinin was demonstrated by a greater mean difference in APTT (P = 0.0001) between specimens spiked with NS or 200 KIU (17.5 +/- 12.2s) vs 400 KIU (27.8 +/- 21.5s) of aprotinin.(ABSTRACT TRUNCATED AT 250 WORDS)

Fatal aortic thrombosis in a neonate during infusion of epsilon-aminocaproic acid

Hemorrhagic complications are common in patients placed on extracorporeal life support (ECLS), especially in those who have additional risk factors. Several centers use epsilon-aminocaproic acid (EACA) in their high-risk ECLS patients in an attempt to decrease the incidence of such complications, despite the fact that no controlled trials have been performed examining the risks and benefits of its use. The authors report the case of a neonate who had fatal aortic thrombosis during EACA administration. Also included is a discussion of the use of EACA in patients who require cardiopulmonary bypass.

Prevention of bleeding after cardiopulmonary bypass with high-dose tranexamic acid. Double-blind, randomized clinical trial

This prospective, double-blind, randomized trial assessed the effectiveness of high-dose tranexamic acid given in the preoperative period on blood loss in patients undergoing cardiopulmonary bypass. One hundred fifty patients scheduled to undergo cardiac operations with cardiopulmonary bypass were randomized into three groups of equal size. The first group received 10 gm of tranexamic acid intravenously over 20 minutes before sternotomy and a placebo infusion over 5 hours. The second group received 10 gm of tranexamic acid over 20 minutes and then another 10 gm infused intravenously over 5 hours. The control group received a placebo bolus and a placebo infusion over 5 hours (0.9% normal saline solution). The blood loss after the operation was measured at 6 hours and 24 hours. The homologous blood and blood products given during and up to 48 hours after operation were recorded. Eighteen percent of the control group patients shed more than 750 ml blood in 6 hours compared with only 2% in both tranexamic acid groups. Patients who shed more than 750 ml blood required 93% more red blood cell transfusions than patients without excessive bleeding. Tranexamic acid (10 gm) given intravenously in the period before cardiopulmonary bypass reduced blood loss over 6 hours by 50% and over 24 hours by 35%. Continued tranexamic acid infusion (10 gm over 5 hours) did not reduce bleeding further. There was no difference in the coagulation profile before operation between patients with and without excessive bleeding. However, coagulation tests done in the postoperative period indicated ongoing fibrinolysis and platelet dysfunction in patients with excessive bleeding.

Clinical comparison of blood oxygenators: a retrospective study

The results for platelet count (PC), activated clotting time (ACT), postoperative bleeding, and hemoderivatives usage in cardiac surgeries were crossed against the type of oxygenator used. These were two bubble and one membrane type. A sample of the surgery population for each type was selected at random. Thus, the patients in this study were divided into 3 groups: BA: 87 patients, bubble oxygenator; BB: 87 patients, bubble oxygenator; M: 73 patients, membrane oxygenator. The groups were statistically similar (p > 0.05) for age, body surface area, cardiopulmonary bypass (CPB) time, and prevalence of cardiac disease. The rate of PC 15 min after CPB end and before its beginning was BA, 0.48 +/- 0.02; BB, 0.49 +/- 0.02; M, 0.55 +/- 0.03. The rate of ACT after protamine administration and before CPB was BA, 1.22 +/- 0.03; BB, 1.16 +/- 0.03; M, 1.16 +/- 0.03. Volume (ml) of total postoperative bleeding (POB) was BA, 904 +/- 72; BB, 963 +/- 73; M, 867 +/- 83. Patient percentage that used hemoderivatives (HD) was BA, 86.3%; BB, 88.5%; M, 90.0%. No statistical difference was found between groups (p > 0.05). This study indicates that although membrane oxygenators have better theoretic and experimental biocompatibility, no significant difference in PC, ACT, POB, and HD usage was observed in the clinical setting. All values are expressed as the mean +/- standard error of the mean.

Metaanalysis of prophylactic drug treatment in the prevention of postoperative bleeding

Prophylactic drug treatment is one of several strategies to reduce postoperative blood loss and potentially limit homologous blood use in open heart surgery. A computerized MEDLINE search supplemented with manual bibliography reviews was performed for randomized clinical trials published in peer-reviewed English-language journals from January 1980 to June 1993. A metaanalysis was conducted of trials evaluating desmopressin (group DD, n = 13), epsilon-aminocaproic acid or tranexamic acid (group EA, n = 4), and aprotinin (group AP, n = 16). Eligible studies used placebo controls and administered the drug in a prophylactic manner. The primary study end point was postoperative chest tube loss (mL, mean +/- standard deviation). There was a significant reduction in postoperative chest tube loss detected for each of the active treatments versus the placebo (DD versus controls: percent reduction 0.11, p = 0.0021; EA versus controls: percent reduction 0.30, p < 0.0001; and AP versus controls: percent reduction 0.36, p < 0.0001). Therapy with EA or AP was associated with a greater reduction in chest tube loss than DD (EA versus DD, p = 0.0033, and AP versus DD, p < 0.0001). Secondary study end points were transfusion requirements, chest reexploration, and perioperative mortality. The volume of postoperative red cell transfusion (mean +/- standard deviation) was reduced with EA (p < 0.0001) or AP treatment (p < 0.0001) compared with a placebo or DD, whereas the proportion of patients given transfusions was limited only in the AP-treated patients (odds ratio 0.23; 95% confidence interval, 0.16 to 0.33; p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Natural and synthetic antifibrinolytics in adult cardiac surgery: efficacy, effectiveness and efficiency

Epsilon-aminocaproic acid and tranexamic acid, two synthetic antifibrinolytics, and aprotinin, an antifibrinolytic derived from bovine lung, are used to reduce excessive bleeding and transfusion of homologous blood products (HBP) after cardiac surgery. This review analyzes the studies on the utilization of antifibrinolytics in adult cardiac surgery according to the epidemiological concepts of efficacy, effectiveness and efficiency. A majority of published studies confirm the efficacy of antifibrinolytics administered prophylactically to reduce postoperative bleeding and transfusion of HBP. More studies are needed, however, to compare antifibrinolytics and determine if any one is superior to the others. Despite their demonstrated efficacy, antifibrinolytics are only one of the options available to diminish the use of HBP. Other blood-saving techniques, surgical expertise, temperature during cardiopulmonary bypass and respect of established transfusion guidelines may modify the effectiveness of antifibrinolytics to the point where antifibrinolytics may not be necessary. At this time, insufficient data have been published to perform a cost vs benefit analysis of the use of antifibrinolytics. This complex analysis takes into account not only direct costs (cost of the drug and of blood products), but also the ensuing effects of treatment such as: length of stay in the operating room, in the intensive care unit and in the hospital; need for surgical re-exploration; treatment of transfusion or drug-related complications, etc. In particular, the risk of thrombotic complications associated with antifibrinolytics is the subject of an ongoing, unresolved controversy.(ABSTRACT TRUNCATED AT 250 WORDS)

Anticoagulation and hemostasis in cardiac surgical patients

Optimizing anticoagulation and hemostasis during cardiopulmonary bypass and perioperatively helps to ensure the best possible clinical outcome. This article reviews the pharmacology of unfractionated and low-molecular weight heparin, aprotinin, desmopressin, dextran, antiplatelet agents, warfarin, and direct thrombin inhibitors. Their use is discussed in the context of coronary artery surgery, valvular surgery, and mechanical cardiac support devices, as well as in the management of acute ischemic syndromes, atrial fibrillation, and prevention and treatment of venous thromboembolism. Progress in the development and utilization of these anticoagulants and antiplatelet agents has supported the major advances that have been achieved in cardiac surgery.

Decreased postoperative drainage with addition of epsilon-aminocaproic acid before cardiopulmonary bypass

Desmopressin (DDAVP, 0.3 microgram/kg) has been used routinely after cardiopulmonary bypass, particularly in patients having antiplatelet therapy. Recently epsilon-aminocaproic acid (single dose of 5 g) given before cardiopulmonary bypass has been added to the protocol. One hundred consecutive patients taking desmopressin and epsilon-aminocaproic acid (group A) and another 100 taking desmopressin alone (group B) were analyzed. There was no difference among these two groups in patient age, sex, preoperative history of bleeding and drug consumption, or number of patients for elective, urgent, emergent, redo, and reoperation for bleeding. Results of routine preoperative coagulation studies were within normal limits in both groups. Preoperative hemoglobin level was 13.5 g/dL in group A and 13.8 g/dL in group B (p = 0.12). Estimated blood loss in the operating room was 513 mL for group A and 587 mL for group B (p = 0.07). The total chest drainage at the end of 24 hours was 492 mL in group A and 746 mL in group B (p = 0.0001). Amicar given before cardiopulmonary bypass does not lessen operating room blood loss, but significantly decreases postoperative chest drainage. Group B patients received more fresh frozen plasma (60 U versus 4 U), more platelets (130 U versus 16 U), and more cryoprecipitate (118 U versus 10 U) than group A patients. Adding epsilon-aminocaproic acid could save $206.18 in blood product use per patient, compared with the expense of $24.12 per patient for E-aminocaproic acid administration.

Improvement in circulatory and oxygenation status by perflubron emulsion (Oxygent HT) in a canine model of surgical hemodilution

To examine the effect of a low dose of Oxygent HT on hemodynamics and oxygen transport variables in a canine model of profound surgical hemodilution, two groups of adult anesthetized splenectomized beagles were hemodiluted with Ringer's solution to Hb 7 g/dL. The treated group received 1 mL/kg Oxygent HT (90% w/v perflubron emulsion [perfluorooctyl bromide], Alliance Pharmaceutical Corp.) and both groups (7 controls and 10 treated) were further hemodiluted using 6% hydroxyethyl starch until cardiorespiratory decompensation occurred. Pulmonary artery catheterization data and oxygen transport variables were recorded at Hb decrements of 1 g/dL breathing room air. There was no difference among groups during initial hemodilution. However, in the Oxygent HT group there was a statistically significant improvement in mean arterial pressure, CVP, cardiac output, PvO2, SvO2, DO2, and pulmonary venous admixture shunt during profound hemodilution to Hb levels of 6, 5, and 4 g/dL. A low dose of Oxygent HT offered benefit in improving hemodynamics and oxygen transport parameters even under air breathing conditions in a model of surgical hemodilution. This effect was most apparent at lower levels of Hb.

Transfusion and surgery

In this survey of transfusion in surgery, we have attempted to provide the surgeon with an understanding of the problems associated with homologous transfusion and a practical knowledge of treatment strategies and alternatives designed to reduce homologous blood exposure. Such a review cannot be encyclopedic. Our hope is that it will serve the reader as a stimulus to examine his or her transfusion practices and as a guide for future self-learning.

Prevention of postbypass bleeding with tranexamic acid and epsilon-aminocaproic acid

In this institution, two antifibrinolytic agents have been in routine use before cardiopulmonary bypass (CPB) to prevent bleeding due to fibrinolysis; epsilon-aminocaproic acid (EACA) or tranexamic acid (TA) are administered as intravenous infusions over 2 hours, from the time of anesthetic induction until the onset of CPB. TA is 10 times more potent and binds more strongly to plasminogen than EACA. Data were collected retrospectively on 411 patients undergoing first-time coronary artery bypass grafting with cardiopulmonary bypass who had received one of four therapy regimens: 10 g of EACA (65 patients), 15 g of EACA (60 patients), 6 g of TA (100 patients), or 10 g of TA (75 patients). Patients who did not receive any drug (91) served as controls. Anesthetic technique and the heparin/protamine protocol did not differ. Blood collected by mediastinal and pleural tubes was autotransfused up to 6 hours postoperatively. Both TA and EACA reduced post-CPB bleeding in the first 24 hours. Ten grams of TA was the most effective, resulting in a 52% and 36% reduction in blood loss over controls at 6 and 24 hours, respectively. Although 10 g of TA was more effective than 6 g of TA in blood loss control for the first 6 hours, the difference was not significant at 24 hours. A significantly lower number of patients in the 10 g TA group received blood products than in control (28% v 49%) patients (P = 0.02). Pretreatment with 10 g of TA prevented excessive (over 750 mL in 6 hours) bleeding after CPB.

Noninflammatory bullae associated with epsilon-aminocaproic acid infusion

Three patients who had cardiac surgery developed a transient, noninflammatory subepidermal bullous eruption on the legs after epsilon-aminocaproic acid infusion. Fibrin thrombi were demonstrated in papillary dermal vessels. The use of epsilon-aminocaproic acid as an antifibrinolytic agent may predispose patients to cutaneous vascular thromboses.

Natural and synthetic antifibrinolytics in cardiac surgery

In an effort to reduce morbidity associated with transfusion of blood products, the use of antifibrinolytics to decrease bleeding and transfusions after cardiopulmonary bypass (CPB) is receiving widespread attention. The predominant haemostatic defect induced by CPB and, therefore, the mechanisms by which natural (aprotinin) or synthetic antifibrinolytics (sigma-amino-caproic acid, tranexamic acid) exert their effects have been difficult to define. Nonetheless, all three substances appear to be effective in the treatment or in the prevention of excessive bleeding associated with cardiac surgery. However, the administration of these drugs should not attempt to replace meticulous surgical and anaesthetic care. In particular, the importance of an appropriate transfusion practice cannot be overemphasized. The efficient use of these, sometimes expensive, drugs must take into account not only the initial cost, but also the short- and long-term economic consequences for the health care provider of using, or not using, a given medication. Unfortunately, the comprehensive data on which authoritative conclusions may be reached are not yet available. Pending availability of these data, the present use of antifibrinolytics at the Montreal Heart Institute is the following: (1) patients undergoing elective primary myocardial revascularization or valve surgery do not receive prophylactic antifibrinolytics; (2) patients undergoing repeat myocardial revascularization, repeat valve surgery, or primary or repeat combined procedures, receive prophylactic sigma-aminocaproic acid; (3) sigma-aminocaproic acid may be used to treat excessive chest drainage in the postoperative period; (4) the prophylactic and the therapeutic uses of low doses of aprotinin are currently under investigation.

Conventional blood conservation techniques in 500 consecutive coronary artery bypass operations

With use of a nonpharmacological, simple, and inexpensive program for blood conservation, 500 consecutive patients underwent elective coronary artery bypass grafting without need of homologous red cell transfusions in 493 (98.6%). At least one internal mammary artery was grafted in all but 1 patient, with supplemental saphenous vein grafts. Intraoperatively, autologous heparinized blood was removed before bypass and retransfused at the conclusion of extracorporeal circulation. The volume remaining in the oxygenator and tubing set was returned without cell processing or hemofiltration. Using the hard-shell cardiotomy reservoir from the heart-lung machine, autotransfusion of the shed mediastinal blood was continued hourly up to 18 hours after operation. The mean postoperative mediastinal blood loss was 643 +/- 354 mL, whereas 624 +/- 296 mL was autotransfused. Thirteen patients (2.6%) needed reexploration for bleeding, of whom 7 (7/500, 1.4%) received homologous blood. No other patients required red cell transfusions. In addition, 9 patients were given a mean of 2.6 units of fresh frozen plasma because of suspected coagulopathy. No platelets were transfused, and no cryoprecipitate therapy was undertaken. Thus, in total, 484 patients (96.8%) were not exposed to any homologous blood products during the hospital stay. At discharge, the mean hemoglobin concentration was 121 +/- 14 g/L (12.1 +/- 1.4 g/dL) and the hematocrit, 0.36 +/- 0.04. Postoperative complications were few. There was one in-hospital death (0.2%).

The stratification of cardiac surgical procedures according to use of blood products: a retrospective analysis of 1480 cases

The use of blood products in 1480 consecutive cases of adult cardiac surgical procedures over a period of 15 mth was studied retrospectively using the database of the Department of Anaesthesia of the Institut de Cardiologie de Montréal. Use of blood products was compared in patients having (1) coronary artery bypass grafting, (2) valvular surgery, (3) or a combination of 1 and 2. First operations were compared with reoperations. Overall, the use of homologous blood products was greatest in patients of Group 3, intermediate in patients of Group 2, and smallest in patients of Group 1. Reoperations were associated with an increase in intraoperative transfusion of packed red blood cells, but postoperative chest drainage was similar to first operations. When all blood products (packed red blood cells, fresh frozen plasma and platelets) were taken into consideration, patients undergoing primary CABG or valve surgery were the least exposed to homologous blood donors (five and six units transfused respectively). Repeat CABG was associated with an intermediate exposure to homologous blood products (eight units). Finally, primary and repeat combined procedures, and repeat valve surgery were associated with the greatest exposure to foreign blood products (10, 13 and 10 units respectively). The data presented in this study provide a rational basis for stratification of procedures according to the expected use of blood products, particularly in view of future studies which may be planned to examine the efficiency of blood conservation strategies.

Treatment of end-stage chronic obstructive pulmonary disease with double lung transplantation

Six patients with end-stage emphysema (age 44 +/- 2 years) underwent double lung transplantation (Tx) from June 1988 through May 1990. All suffered from severe inanition and required oxygen therapy. The ischemic time was 193 +/- 28 minutes. Post-Tx immune suppression was OKT3 (14 days), cyclosporine (trough levels of 150 +/- 25 ng/ml), azathioprine to keep WBC at 3,000 to 5,000/cu mm (1 to 3.0 mg/kg/day) and following OKT3, a tapering prednisone regimen. Two rejection episodes that occurred in two patients on post-Tx day 5 and 10 were treated with bolus doses of methylprednisolone. The mean hospital stay was 32 +/- 7 days (range, 20 to 69 days). Four patients required treatment of cytomegalovirus (CMV) infection: gastritis (+donor, +recipient) in one and CMV pneumonia in two (+donor, -recipient). A fourth (+donor, -recipient) had right-sided Candida empyema six weeks post-Tx, developed CMV and staphylococcal sepsis, and died 64 days post-Tx. One patient required pyloroplasty eight weeks post-Tx and one patient underwent tracheal suture line repair at eight weeks. During a follow-up of 81 patients months (range, 8 to 24 months), one patient had developed Epstein-Barr viral (EBV) induced lymphoproliferative disease in the lung and one patient had developed EBV lymphoma. Three patients are at work, one is continuing rehabilitation, and one is at home. Double lung Tx offers a definitive benefit to patients with emphysema; however, a prolonged postoperative course can be expected. Viral infections remain serious but treatable problems.