Low-dose aprotinin in internal mammary artery bypass operations contributes to important blood saving

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.

Aprotinin for Open Cardiac Surgery in Cyanotic Heart Disease

In a prospective randomized study, aprotinin was assessed in cyanotic children with tetralogy of Fallot undergoing total correction utilizing cardiopulmonary bypass. In group A (n = 25), 20,000 kallikrein inhibiting units of aprotinin per kilogram of body weight was administered before cardiopulmonary bypass and the same amount was added to the pump prime. In group B (n = 25), only a single dose of aprotinin was given before cardiopulmonary bypass. Blood loss and blood product requirements were compared with those in a control group of 25 patients who did not receive aprotinin. Blood loss and blood products used in groups A and B did not differ but the control group had significantly more bleeding and transfusion requirements. A single dose of aprotinin before cardiopulmonary bypass is recommended in cyanotic patients undergoing intracardiac repair.

Comparison of the effects of a cell saver and low-dose aprotinin on blood loss and homologous blood usage in patients undergoing valve surgery

OBJECTIVE

To compare 2 important techniques of blood conservation, use of a cell saver and low-dose aprotinin, in terms of blood loss and homologous blood usage in patients undergoing cardiac valve surgery.

DESIGN

Prospective, randomized.

SETTING

Tertiary care hospital.

PARTICIPANTS

Sixty adult patients undergoing elective valve surgery.

INTERVENTIONS

The patients were divided into 3 groups of 20 each. In group 1, aprotinin in the dose of 30,000 KIU/kg was added to the pump prime, with a further dose of 15,000 KIU/kg added at the end of each hour of cardiopulmonary bypass. In group 2, a cell-saver system was used to collect all blood at the operation site for processing in preparation for subsequent reinfusion. Group 3 patients acted as a control group and underwent routine management, which included collection of autologous blood during the pre-cardiopulmonary bypass period. A hemoglobin of <8 g/dL was considered as an indication for bank blood transfusion in the postoperative period.

MEASUREMENTS AND MAIN RESULTS

The chest tube drainage was significantly less in group 1 compared with groups 2 and 3, with total drainage (median [interquartile range]) amounting to 250 mL [105 to 325 mL] vs. 700 mL [525 to 910 mL] in group 2 and 800 mL [650 to 880 mL] in group 3 (p < 0.001). The patients in groups 1 and 2 required significantly less bank blood (median [interquartile range]) as compared with group 3 (350 mL [0 to 525 mL], 350 mL [0 to 350 mL], and 1050 mL [875 to 1050 mL]; p < 0.001), respectively. Cell saver provided 410 +/- 130 mL of hemoconcentrated blood in group 2. The average preoperative hemoglobin concentration was 11.3 g/dL, and it was around 9 g/dL on the 7th postoperative day. The hemoglobin concentration at various stages during hospitalization in all 3 groups was similar.

CONCLUSIONS

Low-dose aprotinin and a cell saver are effective and comparable methods of blood conservation. Aprotinin helps by decreasing the postoperative drainage, and a cell saver helps by making the patient's own blood available for transfusion.

Anti-fibrinolytic use for minimising perioperative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood have prompted re-consideration of the use of allogeneic (blood from an unrelated donor) blood transfusion.

OBJECTIVES

To assess the effects of the anti-fibrinolytic drugs aprotinin, tranexamic acid, and epsilon aminocaproic acid, on peri-operative red blood cell (RBC) transfusion.

SEARCH STRATEGY

We searched MEDLINE (to May 1998), EMBASE (to December 1997), web sites of international health technology assessment agencies (to May 1998). References in identified trials and review articles were checked and authors contacted to identify any additional studies.

SELECTION CRITERIA

Randomised controlled trials of anti-fibrinolytic drugs in adults scheduled for non-urgent surgery.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data.

MAIN RESULTS

We found 61 trials of aprotinin (7027 participants). Aprotinin reduced the rate of RBC transfusion by a relative 30% (RR=0.70: 95%CI: 0.64 to 0.76). The average absolute risk reduction (ARR) was 20.4% (95%CI: 15.6% to 25.3%). On average, aprotinin use saved 1.1 units of RBC (95%CI: 0.69 to 1.47) in those requiring transfusion. Aprotinin also significantly reduced the need for re-operation due to bleeding (RR=0.40: 95%CI: 0.25 to 0.66). We found 18 trials of tranexamic acid (TXA) (1,342 participants). TXA reduced the rate of RBC transfusion by a relative 34% (RR=0.66: 95%CI: 0.54 to 0.81). This represented an ARR of 17.2% (95%CI: 8.7% to 25.7%). TXA use resulted in a saving of 1.03 units of RBC (95%CI: 0.67 to 1.39) in those requiring transfusion. We found four trials of epsilon aminocaproic acid (EACA) (208 participants). EACA use resulted in a statistically non-significant reduction in RBC transfusion (RR=0.48: 95%CI: 0.19 to 1.19). Comparisons between agents Eight trials made 'head-to-head' comparisons between TXA and aprotinin. There was no significant difference between the two drugs in the rate of RBC transfusion: RR=1.21 (95%CI: 0.83 to 1.76) for TXA compared to aprotinin. Adverse Effects Aprotinin did not seem to be associated with an excess risk of adverse effects, including thrombo-embolic events (thrombosis RR=0.64: 95%CI: 0.31 to 1.31) and renal failure (RR=1.19: 95%CI: 0.79 to 1.79). Fewer data were available for TXA and EACA.

REVIEWER'S CONCLUSIONS

From this review it appears that aprotinin reduces the need for red cell transfusion, and the need for re-operation due to bleeding, without serious adverse effects. However, there was significant heterogeneity in trial outcomes, and some evidence of publication bias. Similar trends were seen with TXA and EACA, although the data were rather sparse. The poor evaluation of these latter drugs is unfortunate as results suggest they may be equally as effective as aprotinin, but are significantly cheaper. The evidence reviewed here supports the use of aprotinin in cardiac surgery. Further small trials of this drug are not warranted. Future trials should be large enough to compare the efficacy and cost-effectiveness of aprotinin with that of TXA and EACA.

Blood loss after coronary artery bypass surgery: relations to patient variables and antithrombotic treatment

Blood loss was studied in 200 patients during and after coronary artery bypass surgery. Half of the patients were receiving dalteparin/heparin treatment for unstable angina and taking acetylsalicylic acid (ASA) 75 mg/d. One stable and four unstable patients were re-explored because of postoperative bleeding (p = 0.17). Median blood loss was 500 ml (range 100-1700 ml) during the operation and 600 ml (range 200-3400 ml) after the operation. Regression analysis showed a correlation between less postoperative bleeding and female gender and larger body mass index. In our subset of patients this correlation was not predicted from unstable angina, ASA treatment, use of aprotinin, age or cardiopulmonary bypass time. The unstable patients had lower haemoglobin levels before the operation and received blood transfusions postoperatively more frequently. A total of 101 patients were given a blood transfusion. Our findings indicate that ASA can be safely continued until the day of isolated coronary artery bypass surgery.

Economic evaluation of high-dose and low-dose aprotinin therapy during cardiopulmonary bypass

BACKGROUND

Aprotinin therapy is now widely used during cardiac surgery. This study examined the clinical and economic effectiveness of high-dose or low-dose aprotinin in comparison to placebo.

METHODS

In a double blind, randomized study, three groups of 50 patients received high-dose aprotinin costing AUS$614 per patient (AUS$ = Australian dollars), low-dose aprotinin costing AUS$220 per patient or placebo. Resource use influenced by aprotinin therapy was measured.

RESULTS

Both doses were effective in reducing chest drainage and postoperative transfusion requirements, high-dose being more effective than low-dose. Both doses reduced the rate of reoperations for hemostasis. A base case of statistically significant differences associated with the high-dose and low-dose aprotinin showed cost savings of AUS$77 and AUS$348 per patient, respectively. If the demonstrated less significant reductions in operating room and ward stay are included, these savings become AUS$463 and AUS$715, respectively. Alternately, if cross-matches are replaced by group-and-hold and cell savers are not used, the savings per patient would be AUS$196 and AUS$467, respectively.

CONCLUSIONS

While high-dose aprotinin is clinically more effective than low-dose aprotinin, low-dose therapy demonstrates greater cost savings.

Platelet function during cardiac surgery and cardiopulmonary bypass with low-dose aprotinin

OBJECTIVE

To determine whether two low-dose regimens of aprotinin influence platelet function.

DESIGN

Prospective, randomized, single-blinded trial.

SETTING

University teaching hospital performing 600 cardiac operations per year.

PARTICIPANTS

Fifty-nine patients scheduled for cardiac surgery undergoing cardiopulmonary bypass (CPB) of expected duration of 60 minutes or more.

INTERVENTIONS

Patients were randomized into three groups. Group C (control) included 21 patients who did not receive aprotinin. In group A2, 17 patients received 14,286 kallikrein inhibitor units (KIU)/kg (2 mg/kg) of aprotinin before surgery, followed by a continuous infusion of 7,143 KIU/kg/h (1 mg/kg/h) until the end of surgery. In group A4, 19 patients received 28,572 KIU/kg (4 mg/kg) of aprotinin before surgery, followed by the same infusion.

MEASUREMENTS AND MAIN RESULTS

Postoperative bleeding and transfusion requirements were significantly less in group A4. Changes in platelet number and function were similar in the three groups. Platelet aggregation was assessed in four periods: before CPB (T1), post-CPB (T2), and 2 hours (T3) and 4 hours (T4) after CPB. Platelet aggregation induced by adenosine diphosphate, 1 and 2 micromol/L; ristocetin, 1 mg/mL; and arachadonic acid (AA), 1.4 mmol/L, decreased at T2 (p < 0.001) in all groups, and for the ristocetin and AA groups, remained at less than baseline values at T3 and T4. In five patients from each group, platelet receptors for glycoprotein IIb-IIIa (GPIIb-IIIa) and expression of platelet activation markers, guanosine monophosphate 140 (GMP-140) and lysosomal protein, were measured by flow cytometry before and after CPB. Modifications in the expression of GPIIb-IIIa were always modest and without statistical significance. Platelet activation markers, GMP-140 or lysosomal protein, nearly doubled from baseline to post-CPB only in the A4 group, whereas they remained stable in both other groups (statistically not significant).

CONCLUSION

The two regimens of aprotinin, both considered low dosage, did not exert a protective effect on platelet function. Neither dose produced changes in platelet GPIIb-IIIa or platelet activation markers. However, bleeding and transfusion needs were decreased.

A retrospective study of the effects of small-dose aprotinin on blood loss and transfusion needs during total hip arthroplasty

Aprotinin is a proteinase inhibitor that reduces blood loss in total hip arthroplasty when administered in large doses. Little is known about the capability of smaller doses of aprotinin in reducing blood loss and transfusion needs in this surgical setting. We reviewed the medical records of 372 patients who had undergone unilateral primary total hip arthroplasty under general anaesthesia during a 6-year period (1989 to 1994) at our institution. Successively, 193 patients had and 179 patients had not received aprotinin in a dose of 20,000 kallikrein inhibitor units per kilogram body weight intravenously before surgery. Neither the volume of red blood cells lost nor that of red blood cells transfused during hospitalization differed significantly between the patients who had and those who had not received aprotinin (520 +/- 406 vs. 549 +/- 394 mL and 463 +/- 379 vs. 475 +/- 367 mL; P = 0.49 and P = 0.76 respectively). These results suggest that small-dose aprotinin was not effective in reducing blood loss and transfusion needs in patients undergoing unilateral primary total hip replacement.

Retrograde autologous priming for cardiopulmonary bypass: a safe and effective means of decreasing hemodilution and transfusion requirements

OBJECTIVES

The obligatory hemodilution resulting from crystalloid priming of the cardiopulmonary bypass circuit represents a major risk factor for blood transfusion in cardiac operations. We therefore examined whether retrograde autologous priming of the bypass circuit would result in decreased hemodilution and red cell transfusion.

METHODS

Sixty patients having first-time coronary bypass were prospectively randomized to cardiopulmonary bypass with or without retrograde autologous priming. Retrograde autologous priming was performed at the start of bypass by draining crystalloid prime from the arterial and venous lines into a recirculation bag (mean volume withdrawal: 880 +/- 150 ml). Perfusion and anesthetic techniques were otherwise identical for the two groups. The hematocrit value was maintained at a minimum of 16% and 23% during and after cardiopulmonary bypass, respectively, in all patients. Patients were well matched for all preoperative variables, including established transfusion risk factors. Subsequent hemodynamic parameters, pressor requirements, and fluid requirements were equivalent in the two groups.

RESULTS

The lowest hematocrit value during cardiopulmonary bypass was 22% +/- 3% versus 20% +/- 3% in patients subjected to retrograde autologous priming and in control patients, respectively (p = 0.002). One (3%) of 30 patients subjected to retrograde autologous priming had intraoperative transfusion, and seven (23%) of 30 control patients required transfusion during the operation (p = 0.03). The number of patients receiving any homologous red cell transfusions in the two groups during the entire hospitalization was eight of 30 (27%; retrograde autologous priming) versus 16 of 30 (53%; control) (p = 0.03).

CONCLUSIONS

These data suggest that retrograde autologous priming is a safe and effective means of significantly decreasing hemodilution and the number of patients requiring red cell transfusion during cardiac operations.

Influence of high- and low-dose aprotinin on activation of hemostasis in open heart operations

BACKGROUND

The protease inhibitor aprotinin reduces hemostatic activation and blood loss after cardiac operations. The aim of the present study was to investigate the influence of two different aprotinin doses on hemostatic activation and to identify the most effective dose to reduce the postoperative bleeding tendency.

METHODS

In a prospective, randomized, double-blind clinical trial, 230 patients scheduled for routine open heart operations received either high-dose (group H) or low-dose (group L) aprotinin. Primary outcome measures were the level of F(1+2) prothrombin fragments as a marker of thrombin generation, the level of D-dimers as an indicator of fibrinolysis, and the amount of postoperative blood loss. Allogeneic blood transfusion was recorded as a secondary outcome measure.

RESULTS

Aprotinin plasma concentrations 5 minutes after the onset of cardiopulmonary bypass were 166 +/- 45 kallikrein inactivator units per milliliter in group H and 118 +/- 30 kallikrein inactivator units per milliliter in group L (p < 0.05). Fibrinolytic activation was reduced significantly in group H compared with group L: the level of D-dimers at the end of CPB was 1,027 +/- 781 ng/mL and 1,977 +/- 1,001 ng/mL, respectively, in the two groups (p < 0.05). However, thrombin generation (F(1+2) fragments) did not differ between the two groups (7.4 +/- 3.5 nmol/L in group H and 8.6 +/- 4.3 nmol/L in group L). Twenty-four-hour postoperative blood loss was 663 +/- 461 mL in group H compared with 877 +/- 513 mL in group L (p < 0.05), and the corresponding allogeneic blood requirement was 1.3 +/- 1.9 U in group H and 1.9 +/- 2.3 U in group L (p < 0.05).

CONCLUSIONS

A high-dose aprotinin regimen was significantly more effective than a low-dose regimen in attenuating fibrinolysis and reducing the bleeding tendency and allogeneic blood requirements, but not in reducing F(1+2) prothrombin fragments. High-dose aprotinin therapy appears to be superior to low-dose therapy.

Aprotinin Fifteen Years Later

Aprotinin, the broad-based bovine serine protease inhibitor, was first used as an antidote against the harmful proteases released through complement-induced neutrophil activation in the early 1980s. Since then, the safety and efficacy of aprotinin have been debated. Even now, fifteen years later, aprotinin's precise mechanism of action and clear indications for use have not been defined. This article discusses what aprotinin is, its role in the contact system of blood, how it improves hemostasis, the effect of temperature on it, its use in clinical practice, and which patients should receive it. The article concludes that aprotinin's hemostatic effects are useful in patients who are at increased risk from bleeding, but that it should not be considered a substitute for surgical skill. Early claims of absolute safety were premature. Risks between high- and low-dose regimens vary significantly, and more study is required. Alternatives to aprotinin such as the less expensive antifibrinolytic agent tranexamic acid are now available, but they also require additional study.

Early Results with Bilateral and Single Internal Mammary Artery Grafts. Are They Different?

Between June 1991 and June 1996, 391 patients underwent isolated myocardial revascularization using bilateral internal mammary artery. Three hundred and sixty-five of these patients could be matched retrospectively on the basis of preoperative characteristics with 365 patients operated on during same period who had left internal mammary artery as a single or sequential graft with additional vein grafts. The cardiopulmonary bypass times and aortic cross-clamp times were similar in both groups. There were no statistically significant differences in the two groups in terms of operative mortality (0.55% versus 0.82%), perioperative myocardial infarction (2.46% versus 2.19%), low cardiac output (1.64% versus 1.09%), reexplorations (1.10% versus 1.92%), wound complications (1.10% versus 2.46%), length of stay in the intensive care unit, and total hospital stay. The incidence of respiratory, central nervous system, and renal complications showed no difference between the two groups. Logistic regression analysis showed that the number of internal mammary artery grafts was not a predictor for perioperative complications. If better long-term event-free survival is associated with the use of bilateral internal mammary artery, it should be used wherever possible.

Methylprednisolone and full-dose aprotinin reduce reperfusion injury after cardiopulmonary bypass

OBJECTIVE

To compare the effects of low- and full-dose aprotinin to methylprednisolone (MPS) in reducing cardiopulmonary bypass (CPB)-induced interleukin-6 (IL-6) release.

DESIGN

Prospective, randomized, blinded study.

SETTING

Cytokine Laboratory, pharmacology department, in a university teaching hospital.

PARTICIPANTS

Forty adult male human patients scheduled for myocardial revascularization were divided into four groups (n = 10): (1) control; (2) MPS, 1 g IV before CPB; (3) aprotinin-low-dose protocol; and (4) aprotinin-full-dose protocol.

MEASUREMENTS AND MAIN RESULTS

Plasma levels of IL-6 were measured at baseline and 1 and 24 hours after CPB by enzyme-linked immunosorbent assay technique. Group 1 demonstrated a significant (p < 0.05) increase in IL-6 at 1 and 24 hours post-CPB. Groups 2 and 4 demonstrated significant (p < 0.05) reduction of IL-6 at 1 (group 2 only) and 24 (groups 2 and 4) hours post-CPB when compared with group 1 at the same time periods.

CONCLUSIONS

These results demonstrate that MPS, 1 g before CPB, and full-dose aprotinin, but not half-dose aprotinin, achieve significant reduction in IL-6 release after CPB. These results further suggest that MPS and full-dose aprotinin may reduce reperfusion injury after CPB.

Aprotinin for primary coronary artery bypass grafting: a multicenter trial of three dose regimens

BACKGROUND

High-dose aprotinin reduces transfusion requirements in patients undergoing coronary artery bypass grafting, but the safety and effectiveness of smaller doses is unclear. Furthermore, patient selection criteria for optimal use of the drug are not well defined.

METHODS

Seven hundred and four first-time coronary artery bypass grafting patients were randomized to receive one of three doses of aprotinin (high, low, and pump-prime-only) or placebo. The patients were stratified as to risk of excessive bleeding.

RESULTS

All three aprotinin doses were highly effective in reducing bleeding and transfusion requirements. Consistent efficacy was not, however, demonstrated in the subgroup of patients at low risk for bleeding. There were no differences in mortality or the incidences of renal failure, strokes, or definite myocardial infarctions between the groups, although the pump-prime-only dose was associated with a small increase in definite, probable, or possible myocardial infarctions (p = 0.045).

CONCLUSIONS

Low-dose and pump-prime-only aprotinin regimens provide reductions in bleeding and transfusion requirements that are similar to those of high-dose regimens. Although safe, aprotinin is not routinely indicated for the first-time coronary artery bypass grafting patient who is at low risk for postoperative bleeding. The pump-prime-only dose is not currently recommended because of a possible association with more frequent myocardial infarctions.

Clotting and fibrinolytic disturbance during lung transplantation: effect of low-dose aprotinin. Groningen Lung Transplant Group

Patients undergoing lung transplantation are often confronted with a bleeding problem that may be due in part to the use of cardiopulmonary bypass and its activation of blood clotting and fibrinolysis.

OBJECTIVE

We performed a prospective study to determine whether and to what extent the clotting and fibrinolytic systems are being activated and whether low-dose aprotinin is effective in inhibiting blood activation during lung transplantation.

METHODS

Thirty lung transplantations performed on 29 patients were divided into a group with cardiopulmonary bypass alone (n = 12), a group with cardiopulmonary bypass and 2 x 10(6) KIU aprotinin administered at the beginning of bypass in the pump prime (n = 12), and a group without cardiopulmonary bypass (n = 6). Serial blood samples were taken from the recipient before anesthesia, seven times during the operation, and 4 and 24 hours thereafter.

RESULTS

Results show that in the group having cardiopulmonary bypass alone, the concentration of the clotting marker thrombin/antithrombin III complex increased significantly during the early phase of the operation (p < 0.01) and remained high until the end of the operation. Levels of tissue-type plasminogen activator, a trigger of fibrinolysis released by injured endothelium, also increased sharply in the early phase of the operation in the cardiopulmonary bypass group (p < 0.01), followed by a significant increase in fibrin degradation products (p < 0.01). In the aprotinin group, a significant reduction of thrombin/antithrombin III complex (p < 0.05), tissue-type plasminogen activator (p < 0.05), and fibrin degradation products (p < 0.05) was observed in the early phase of the operation compared with levels in the bypass group, but these markers increased late during bypass associated with a significant drop (p < 0.05) of plasma aprotinin level monitored by plasmin inhibiting capacity. In the nonbypass group, concentrations of thrombin/antithrombin III complex and tissue-type plasminogen activator also rose significantly (p < 0.05) in the early phase of the operation, but the levels were significantly lower than those of the bypass group (p < 0.05). Blood loss during the operation was 2521 +/- 550 ml in the bypass group, 1991 +/- 408 ml in the aprotinin/bypass group, and 875 +/- 248 ml in the nonbypass group.

CONCLUSION

These results suggest that clotting and fibrinolysis are activated during lung transplantation, especially in patients undergoing cardiopulmonary bypass. Aprotinin in a low dose significantly reduced activation of clotting and fibrinolysis in the early phase of the operation but not during the late phase of lung transplantation.

The efficacy of single-dose aprotinin 2 million KIU in reducing blood loss and its impact on the incidence of deep venous thrombosis in patients undergoing total hip replacement surgery

STUDY OBJECTIVE

To evaluate the efficacy of a 2 million KIU single dose of aprotinin on blood loss, transfusion requirements, and incidence of deep venous thrombosis (DVT) in patients undergoing total hip replacement surgery.

DESIGN

Randomized study.

SETTING

Operating theater at an orthopedic hospital.

PATIENTS

40 adult patients scheduled for total hip replacement surgery.

INTERVENTIONS

Patients were randomized to two groups. Group A (n = 20) received 2 million KIU of aprotinin over 20 minutes, Group C (n = 20), the control group, received placebo. Anesthesia and surgical technique were standardized. MEASUREMENTS AND MAIN-RESULTS: Intraoperative blood loss, postoperative blood loss, transfusion requirements (48 hr), hemoglobin, coagulation parameters, and platelet counts were assessed. On the seventh postoperative day, all patients in both groups underwent venography to ascertain the incidence of DVT. We found no significant difference in blood loss or transfusion requirements between the two groups. Intraoperative and postoperative blood losses, coagulation parameters, and incidence of DVT did not differ significantly between the two groups.

CONCLUSION

A single 2 million KIU bolus dose of aprotinin does not reduce perioperative blood loss or transfusion requirements. Aprotinin therapy, when used in conjunction with other antithrombotic therapies, does not increase the incidence of DVT after major orthopedic surgery.

Aprotinin and methylprednisolone equally blunt cardiopulmonary bypass-induced inflammation in humans

Cardiopulmonary bypass induces an inflammatory state characterized by tumor necrosis factor-alpha release. Integrin CD11b is a neutrophil surface adhesive glycoprotein integrin that is rapidly and permanently unregulated by tumor necrosis factor-alpha exposure. The CD11b integrin is known to be the primary neutrophil integrin responsible for neutrophil lung and myocardial entrapment after cardiopulmonary bypass and subsequent reperfusion injury. Twenty-four adults admitted to the hospital for myocardial revascularization were equally randomized to one of three groups: group A (control), group B (methylprednisolone before cardiopulmonary bypass), and group C (low-dose aprotinin protocol). Blood was collected at three times: (1) baseline, (2) 50 minutes of cardiopulmonary bypass duration, and (3) 30 minutes after cardiopulmonary bypass termination. Neutrophil CD11b integrin expression was measured by fluorescence-activated cell sorter analysis and plasma tumor necrosis factor-alpha levels measured by enzyme-linked immunosorbent assay. Group A demonstrated significant (p < 0.05) increases in CD11b expression at times 2 and 3 when results were compared with those of the same group baseline and with those of groups B and C at similar times. No significant changes were noted between groups B and C at any time. Group A demonstrated a significant (p < 0.05) increase in levels of tumor necrosis factor-alpha at time 3 when results were compared with those of the same group baseline and of groups B and C at the same time. No significant changes were noted between B and C at any time. These results demonstrate low-dose aprotinin has a similar antiinflammatory effect to that of methylprednisolone in blunting cardiopulmonary bypass-induced systemic tumor necrosis factor-alpha release and neutrophil integrin CD11b upregulation.

A multicenter, double-blind, placebo-controlled trial of aprotinin for reducing blood loss and the requirement for donor-blood transfusion in patients undergoing repeat coronary artery bypass grafting

BACKGROUND

Aprotinin is a serine protease inhibitor that reduces blood loss and transfusion requirements when administered prophylactically to cardiac surgical patients. To examine the safety and dose-related efficacy of aprotinin, a prospective, multicenter, placebo-controlled trial was conducted in patients undergoing repeat coronary artery bypass graft (CABG) surgery.

METHODS AND RESULTS

Two hundred eighty-seven patients were randomly assigned to receive either high-dose aprotinin, low-dose aprotinin, pump-prime-only aprotinin, or placebo. Drug efficacy was determined by the reduction in donor-blood transfusion up to postoperative day 12 and in postoperative thoracic-drainage volume. The percentage of patients requiring donor-red-blood-cell (RBC) transfusions in the high- and low-dose aprotinin groups was reduced compared with the pump-prime-only and placebo groups (high-dose aprotinin, 54%; low-dose aprotinin, 46%; pump-prime only, 72%; and placebo, 75%; overall P = .001). The number of units of donor RBCs transfused was significantly lower in the aprotinin-treated patients compared with placebo (high-dose aprotinin, 1.6 +/- 0.2 U; low-dose aprotinin, 1.6 +/- 0.3 U; pump-prime-only, 2.5 +/- 0.3 U; and placebo, 3.4 +/- 0.5 U; P = .0001). There was also a significant difference in total blood-product exposures among treatment groups (high-dose aprotinin, 2.2 +/- 0.4 U; low-dose aprotinin, 3.4 +/- 0.9 U; pump-prime-only, 5.1 +/- 0.9 U; placebo, 10.3 +/- 1.4 U). There were no differences among treatment groups for the incidence of perioperative myocardial infarction (MI).

CONCLUSIONS

This study demonstrates that high- and low-dose aprotinin significantly reduces the requirement for donor-blood transfusion in repeat CABG patients without increasing the risk for perioperative MI.

Recombinant aprotinin in coronary artery bypass graft operations

OBJECTIVE

To evaluate the role of recombinant bovine aprotinin in reducing blood loss in coronary artery bypass graft surgery.

DESIGN

An open-label, randomized, controlled study evaluating two dosage levels of recombinant aprotinin.

SETTING

Two acute care hospitals (Northwestern Memorial Hospital, Chicago, Ill., and the Scott & White Memorial Hospital, Temple, Texas).

PATIENTS

Patients undergoing primary and reoperation coronary artery bypass grafting were assigned to groups by means of a computer-generated table of random numbers. Treated (n = 48) and control (n = 36) patients did not differ significantly in age, sex, weight, number of grafts, or preoperative hemoglobin level.

INTERVENTIONS

Recombinant aprotinin was given at two dosages. Dosage level 1 consisted of a bolus of 2 mg/kg intravenously immediately after the induction of anesthesia, 1 mg/kg added to each liter of the oxygenator prime, and 0.5 mg.kg-1.hr-1 infused continuously during operation. At dosage level 2, doses were doubled. Intraoperative monitoring of anti-factor Xa activity was performed, and additional doses of heparin were given on the basis of anti-factor Xa results.

MAIN OUTCOME MEASURES

Preoperative and postoperative hemoglobin levels, amounts of autotransfusion device and chest tube drainage blood, and transfusions of allogeneic red blood cells. Adverse clinical events (alterations in renal function, graft thrombosis, myocardial infarction, and death) were recorded.

RESULTS

Additional heparin was given to 48% patients in the aprotinin group and to 44% of control patients. Overall red blood cell loss (in milliliters, mean +/- standard deviation [SD]) was decreased with aprotinin at dosage level 1 for reoperations (1040 +/- 162 vs 1544 +/- 198, p < 0.01), and at dosage level 2 for all operations (primary operations, 886 +/- 362 vs 1333 +/- 618, p = 0.02; reoperations, 1191 +/- 560 vs 1815 +/- 1116, p = 0.2). Fewer patients in the aprotinin than in the control group had transfusions of donated blood (6/48 vs 12/36, p = 0.02) or reinfusion of chest tube drainage blood (12/48 vs 20/36, p < 0.01). Among patients receiving dosage level 1, there were no myocardial infarctions or deaths. At dosage level 2, one patient had profound bradycardia and died on day 12 and two patients had late graft closures. Two control patients had hypotension after bypass necessitating intraaortic balloon pumps, and one of these patients died. Postoperative increases in blood urea nitrogen and creatinine levels were small in both aprotinin and control groups. No hypersensitivity or other allergic reactions occurred.

CONCLUSION

We conclude that, at the dosages given, recombinant bovine aprotinin decreases surgical blood loss and transfusion requirements in patients undergoing coronary artery bypass grafting, but its use requires appropriate monitoring of heparin use during bypass. Whether higher dosages of aprotinin increase the risk of graft thrombosis must be further assessed with a larger patient sample.

Systemic blood activation with open and closed venous reservoirs

In 20 patients undergoing coronary artery bypass grafting, we studied prospectively systemic blood activation, blood loss, and the need for donor blood when using an extracorporeal circuit equipped at random with one of two different venous reservoirs. In 10 patients we used an open venous reservoir system (ORS) consisting of a hard shell venous reservoir with an integral cardiotomy filter, and in 10 patients we used a closed reservoir system consisting of a collapsible venous reservoir and separate cardiotomy reservoir. Concentrations of complement 3a, elastase, thromboxane B2, and fibrin degradation products showed a biphasic course, especially in ORS patients. During bypass, we observed a first peak of levels of complement 3a, thromboxane B2, fibrin degradation products, and elastase, which was higher in ORS patients than in patients with the closed system, because their blood continuously contacted the foreign materials of the filter and air in the open reservoir, which was avoided in the closed reservoir. Intensive blood-foreign material contact also caused the highest (p < 0.05) hemolysis in ORS patients. The larger amount of hemolytic products in ORS patients theoretically resulted in a temporary decrease in capacity of their Kupffer cells to clear endotoxin released after aortic declamping. This theory might explain the significantly (p < 0.01) higher second peak of activated products after declamping that was observed in ORS patients. Due to increased blood activation, the largest (p < 0.001) amount of shed blood loss, greatest (p < 0.05) need for colloid-crystalloid infusion, and largest (not significant) need for donor blood were found in ORS patients (0.8 +/- 0.4 versus 0.2 +/- 0.2 units of packed cells).(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)

The impact of aprotinin on coronary artery bypass graft patency

STUDY DESIGN

Aprotinin has recently been shown to reduce postoperative bleeding and transfusion requirements associated with coronary artery bypass grafting. One concern with its use, however, is that it may have a deleterious effect on graft patency because it promotes hemostasis. Forty-seven patients undergoing coronary artery bypass. Forty-seven patients undergoing coronary artery bypass grafting were enrolled in a prospective, randomized double-blind trial of aprotinin to determine the effect of this agent on postoperative bleeding, transfusion requirements, renal function, and graft patency. The study group was comprised of the 32 patients who underwent technically adequate ultrafast CT scans 6 to 8 weeks postoperatively to determine graft patency. Sixteen patients received aprotinin (aprotinin group) and 16 received placebo (control group).

RESULTS

Demographic and operative descriptors were comparable between groups. Postoperative mediastinal and chest tube drainage in the aprotinin group was significantly less than that in the control group (722 vs 1,540 mL; p = 0.0006) and the mean blood transfusion requirements were less, but this did not reach significance (125 vs 297 mL; p = 0.42). Analysis of graft patency by patients revealed that 5 patients in the aprotinin group (31%) had at least one occluded graft, while none of the patients in the control group had an occluded graft (p = 0.04). Analysis by graft revealed that 38 of 43 grafts placed in the aprotinin group were patent, while all 38 grafts placed in the placebo group were patent (88.4 vs 100%; p = 0.057). There was no difference in the incidence of myocardial infarction, renal dysfunction or hematologic indexes at discharge between the groups, or evidence of other thrombotic complications.

CONCLUSION

We conclude that high-dose aprotinin is effective in reducing hemorrhage after coronary artery bypass grafting. However, its routine use should be approached cautiously due to its possible adverse effects on graft patency.

Similar hospital morbidity with the use of one or two internal thoracic arteries

The hospital morbidity and mortality of 100 patients operated with two internal thoracic arteries with or without additional vein grafts (BITA group) were compared with a matched group of 100 patients operated with one left internal thoracic artery (ITA) on the anterior descending artery with additional vein grafts (LITA control group). In each study group, 3% of the patients had diabetes mellitus. There was no statistical significant difference in hospital mortality (1% versus 0%), perioperative myocardial infarction (5% versus 1%), low cardiac output (3% versus 5%), rethoracotomy (1% versus 0%), lung complications (13% versus 13%), wound complications (8% versus 8%), other cardiac complications (26% versus 16%), other noncardiac complications (1% versus 4%), median duration of stay in the intensive care unit (1 versus 1 day), and mean duration of stay in the hospital (10.4 versus 10.8 days) between the groups. Logistic regression analysis showed that the number of ITAs used was not a predictor of complications. Thus, there is no difference between the BITA and LITA control group in hospital mortality and morbidity (in patients with a low incidence of diabetes). If an improvement in cardiac event-free and reoperation-free survival is to be expected, the use of both ITAs can be continued in similar patients.

Continuous retrograde hypothermic low flow cerebral perfusion during aortic arch surgery

Continuous retrograde hypothermic low flow cerebral perfusion (CRCP) with deep hypothermic systemic circulatory arrest (DHSCA) during aortic arch surgery was employed in six patients, aged 21-79 years. From August 1991 to November 1992, five of these patients were operated for ascending and arch aortic dissection type I, and one patient was operated for an aneurysm extending from the ascending aorta into the arch. Cardiopulmonary bypass (CPB) technology included a centrifugal pump and low-dose aprotinin. Venous drainage was established via the superior and inferior caval veins and arterial return via the femoral artery. Prior to CPB, a bypass line connecting the arterial line with the superior vena cava cannula was implemented. Prior to DHSCA, the patients were systemically cooled to a mean nasopharyngeal temperature of 15.2 degrees C. After induction of systemic circulatory arrest, the femoral artery cannula was clamped. Thereafter, the implemented bypass line was opened to achieve reverse flow into the superior vena cava to allow venoarterial perfusion. The perfusate was returned to the CPB circuit through drainage from the inferior caval vein and by aspiration of blood from the opened aortic arch. CRCP flow rate ranged from 250 to 450 ml/min (mean 375 ml/min) maintaining an internal jugular vein pressure between 18 and 25 mmHg. The duration of CRCP ranged from 24 to 55 minutes (mean 39 minutes). Postoperatively, one patient died of cardiac failure. The other five patients regained full consciousness without neurological deficits, as defined by the Glasgow coma score, within 48 hours after the operation. Neither did we see other major organ complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Perioperative approaches to coagulation defects

Cardiac surgical procedures are known to be associated with coagulation defects and disordered hemostasis. Excessive perioperative and postoperative bleeding and the need for considerable volumes of blood and blood product transfusions are well recognized. The risks of blood transfusion with high donor-exposure levels have focused attention on blood conservation as a priority in reducing the complications of cardiac operations. Hemostatic defects may be related to patient-inherent coagulopathies, preexisting associated pathology, and preoperative drug therapy. In addition, hemostatic defects are induced during the operation itself. Two principal therapeutic approaches to this complex problem have evolved. Although different, these approaches are not mutually exclusive and may be used complementarily. The first is autotransfusion and the second is hemostatic drug therapy. Although many drugs have been tried, including antifibrinolytic agents (epsilon-aminocaproic acid, tranexamic acid), platelet-preserving agents (prostacyclin, dipyridamole), and desmopressin, the only drug that has shown significant and consistent efficacy in reducing bleeding in cardiac surgery patients is the serine protease inhibitor aprotinin. Aprotinin has been shown to be highly effective in reducing blood loss and blood and blood product transfusion requirements in high-risk patients. Clinical experience with aprotinin therapy in cardiac patients and specific issues such as dosage regimens and the target automated clotting time levels in patients on high-dose aprotinin therapy are outlined. Indications for the use of aprotinin and the balance between risk and benefit are discussed.

Intraoperative predonation contributes to blood saving

The merits of reinfusing prebypass-removed autologous blood (intraoperative predonation) to salvage blood and improve postoperative hemostasis are still debated, specifically for patients at a higher risk for bleeding. To evaluate the effect of intraoperative predonation on the platelet count, blood hemoglobin content, and blood saving postoperatively, we retrospectively studied 100 matching patients. All patients underwent internal mammary artery bypass surgery resulting in a considerable blood loss postoperatively. Intraoperative predonation (800 ml), reinfusion of the residual volume of the extracorporeal circuit, autotransfusion of shed blood, and acceptance of normovolemic anemia postoperatively was the approach adopted in 50 patients (group 1). A similar blood salvage program, excluding intraoperative predonation, was carried out in the other 50 patients (group 2), and these served as the control group. The platelet counts and blood hemoglobin content were significantly higher postoperatively (p < 0.01) in the predonated patients than in the control patients. However, the net blood loss, the amount of retransfused shed blood, and the blood requirements postoperatively were significantly less (p < 0.01) in the predonated patients than in the control patients, whereas 65% of the predonated patients versus 10% of the control patients did not need any donor blood products. In conclusion, predonation reduces the postoperative blood loss and thereby importantly ameliorates the blood-saving effect of a blood salvage program after IMA procedures.

Effect of reduced aprotinin dosage on blood loss and use of blood products in patients undergoing cardiopulmonary bypass

High-dose aprotinin reduces bleeding after cardiac surgery, but has also evoked concern with regard to potential side effects and hospital costs. To evaluate the effects of reduced-dose aprotinin on blood loss and need for blood transfusion, 40 patients undergoing myocardial revascularization were studied (double-blind, placebo-controlled). Postoperative bleeding was reduced by 40% and erythrocyte infusion by 85% in the group given 3 x 10(6) KIU aprotinin (1 x 10(6) as a loading dose before cardiopulmonary bypass, 1 x 10(6) in the priming volume and 2.5 x 10(5)/hour intraoperatively) Aprotinin concentrations during the operation were monitored and maintained above the required level. There were no adverse effects of the drug. Hospital expenditure on blood products was reduced by 51% when aprotinin was used. Our study suggests that aprotinin in reduced dosage diminishes bleeding and requirements for blood products, and that it should be given before, during and after cardiopulmonary bypass.