Reexploration for hemorrhage following coronary artery bypass grafting: incidence and risk factors. Northern New England Cardiovascular Disease Study Group

Recombinant Factor VIIa for Life-Threatening Bleeding in High-Risk Cardiac Surgery Despite Full-Dose Aprotinin

We report the case of an orthotopic heart transplant in a patient with multiple previous cardiac surgeries. The case was prolonged and complicated by severe coagulopathy and bleeding despite the use of full-dose aprotinin throughout. Bleeding was not controlled after 30 U of platelets, 20 U of fresh frozen plasma, and 10 U of cryoprecipitate. However, after the administration of recombinant factor VIIa 90 microg/kg, the rate of bleeding slowed dramatically and no further factor replacement was required. There was no evidence of unwanted clot formation within the newly transplanted heart or around the intraaortic balloon pump that remained in situ for 72 h postoperatively. With the combined risks of coagulopathy and bleeding as well as acute right ventricular failure with increases in pulmonary vascular resistance, the re-do sternotomy for heart transplant seems to be an ideal situation in which to consider the use of recombinant factor VIIa.

Comparison of structured use of routine laboratory tests or near-patient assessment with clinical judgement in the management of bleeding after cardiac surgery

BACKGROUND

Using algorithms based on point of care coagulation tests can decrease blood loss and blood component transfusion after cardiac surgery. We wished to test the hypothesis that a management algorithm based on near-patient tests would reduce blood loss and blood component use after routine coronary artery surgery with cardiopulmonary bypass when compared with an algorithm based on routine laboratory assays or with clinical judgement.

METHODS

Patients (n=102) undergoing elective coronary artery surgery with cardiac bypass were randomized into two groups. In the point of care group, the management algorithm was based on information provided by three devices, the Hepcon, thromboelastography and the PFA-100 platelet function analyser. Management in the laboratory test group depended on rapidly available laboratory clotting tests and transfusion of haemostatic blood components only if specific criteria were met. Blood loss and transfusion was compared between these two groups and with a retrospective case-control group (n=108), in which management of bleeding had been according to the clinician's discretion.

RESULTS

All three groups had similar median blood losses. The transfusion of packed red blood cells (PRBCs) and blood components was greater in the clinician discretion group (P<0.05) but there was no difference in the transfusion of PRBCs and blood components between the two algorithm-guided groups.

CONCLUSION

Following algorithms based on point of care tests or on structured clinical practice with standard laboratory tests does not decrease blood loss, but reduces the transfusion of PRBCs and blood components after routine cardiac surgery, when compared with clinician discretion. Cardiac surgery services should use transfusion guidelines based on laboratory-guided algorithms, and the possible benefits of point of care testing should be tested against this standard.

Predictors of transfusion requirements for cardiac surgical procedures at a blood conservation center

BACKGROUND

Previous studies defining perioperative risk factors for allogeneic transfusion requirements in cardiac surgery were limited to highly selected cardiac surgery populations or were associated with high transfusion rates. The purpose of this study was to determine perioperative risk factors and create a formula to predict transfusion requirements for major cardiac surgical procedures in a center that practices a multimodality approach to blood conservation.

METHODS

We performed an observational study on 307 consecutive patients undergoing coronary artery bypass grafting, valve, and combined (coronary artery bypass grafting and valve) procedures. An equation was derived to estimate the risk of transfusion based on preoperative risk factors using multivariate analysis. In patients with a calculated probability of transfusion of at least 5%, intraoperative predictors of transfusion were identified by multivariate analysis.

RESULTS

Thirty-five patients (11%) required intraoperative or postoperative allogeneic transfusions. Preoperative factors as independent predictors for transfusions included red blood cell mass, type of operation, urgency of operation, number of diseased vessels, serum creatinine of at least 1.3 mg/dL, and preoperative prothrombin time. Intraoperative factors included cardiopulmonary bypass time, three or fewer bypass grafts, lesser volume of acute normovolemic hemodilution removed, and total crystalloid infusion of at least 2,500 mL. The derived formula was applied to a validation cohort of 246 patients, and the observed transfusion rates conformed well to the predicted risks.

CONCLUSIONS

A multimodality approach to blood conservation in cardiac surgery resulted in a low transfusion rate. Identifying patients' risks for transfusion should alter patient management perioperatively to decrease their transfusion rate and make more efficient use of blood resources.

Current status of antifibrinolytics in cardiopulmonary bypass and elective deep hypothermic circulatory arrest

Cardiopulmonary bypass (CPB) results in many physiologic derangements, including activation of the hemostatic and fibrinolytic pathways. Deep hypothermic circulatory arrest (DHCA) adds a further insult to the coagulation systems because it involves more extreme hypothermia and organ ischemia related to blood stasis. The abnormalities induced by CPB disrupt the checks and balances in the hemostatic and fibrinolytic systems, resulting in a pathologic state that leads to excessive bleeding and other perioperative complications. Prophylactic antifibrinolytic therapy can attenuate the response to this insult by restoring the delicate balance within these systems, potentially reducing the complication rate and improving patient outcomes.

Effect of preoperative aspirin use in off-pump coronary artery bypass operations

BACKGROUND

The effect of preoperative aspirin use until the day of operation on mortality rate and bleeding risks in patients who had on-pump coronary artery bypass operation has been well documented. However, the effect of aspirin use in patients undergoing off-pump coronary artery bypass operation (OPCAB) with regard to postoperative blood loss and morbidity has not been studied. We aimed to determine the effects of continuing aspirin therapy preoperatively.

METHODS

We performed a retrospective study of 340 patients who had first-time OPCAB between January 1998 and September 2001. A propensity score for receiving aspirin until the day of operation was constructed from core patient characteristics. All aspirin users (n = 170) were matched with unique 170 nonaspirin users by identical propensity score. The primary outcome measures were in-hospital mortality rate and hemorrhage-related outcomes (postoperative blood loss in the intensive care unit, reexploration for bleeding, and blood product requirements). Secondary outcome measures were stroke, myocardial infarction, gastrointestinal bleeding, and sternal wound infections.

RESULTS

There were no differences in patient characteristics between aspirin users and nonaspirin users. The average postoperative blood loss (845 mL versus 775 mL; p = 0.157) and the rate of reexploration for bleeding (3.5% versus 3.5%; p > 0.99) were similar in aspirin users and nonaspirin users. We found no significant difference between blood product requirements for the two groups. Similarly, we found no significant difference in the incidence of the secondary outcomes.

CONCLUSIONS

Preoperative aspirin did not increase bleeding-related complications, mortality rate, or other morbidities in patients who had off-pump coronary artery operation.

Age and left ventricular impairment predict reopening for bleeding

Statistical analysis of data collected prospectively from all patients undergoing surgery under cardiopulmonary bypass from September 1994 to November 1998 (group 1) was performed to identify preoperative risk factors for reopening for bleeding. Multiple logistic regression analysis of 19 preoperative variables was carried out with reoperation for bleeding as the endpoint. The protocol for intraoperative use of aprotinin was then changed to include high-risk patients. Data collected from all subsequent patients from May 1999 to March 2002 (group 2) were analyzed. Subgroup analyses on primary isolated coronary artery surgery were also performed. Data were obtained from 1,946 patients aged 22 to 88 years (mean, 62.5 years). Older age, severe left ventricular impairment, redo surgery, and chronic renal failure were the independent predictors of reopening for bleeding in group 1. There were no independent predictors of reopening in group 2. Older age and chronic renal failure were the predictors of reexploration for bleeding in patients undergoing primary isolated coronary artery grafting. Prophylactic measures to prevent excessive bleeding should be used in elderly patients and those with severe left ventricular impairment, redo surgery, and chronic renal failure.

Volume expansion with albumin decreases mortality after coronary artery bypass graft surgery

OBJECTIVES

Albumin and nonprotein colloids (starches, dextran, and others) are used frequently as blood volume expanders in coronary artery bypass graft (CABG) surgery. The objective of this study was to determine differences between colloids with regard to patient characteristics and mortality rates.

DESIGN AND SETTING

Discharge data collected in the Solucient Clinical Pathways Database from 19,578 patients undergoing CABG surgery were analyzed.

MEASUREMENTS

Patients receiving albumin and nonprotein colloids were compared with regard to baseline patient characteristics. A multiple regression model was developed to determine if albumin use was independently associated with mortality rates.

RESULTS

Albumin was used in 8,084 cases (41.3%). The use of albumin and nonprotein colloids was not related to patient characteristics. Mortality was lower in the albumin group compared to the nonprotein colloid group (2.47% vs 3.03%, p = 0.02). In the multivariable logistic regression analysis, albumin use was associated with 25% lower odds of mortality compared to nonprotein colloid use (odds ratio, 0.80; 95% confidence interval, 0.67 to 0.96).

CONCLUSION

Colloid administration in CABG surgery was unrelated to patient characteristics. Albumin use appears to be associated with lower incidence of mortality after CABG surgery compared to nonprotein colloid use.

Single-dose tranexamic acid reduces postoperative bleeding after coronary surgery in patients treated with aspirin until surgery

Tranexamic acid reduces postoperative bleeding after coronary artery bypass grafting. We evaluated the effects of a single dose of tranexamic acid given immediately before cardiopulmonary bypass (CPB) in patients treated with aspirin until the day before surgery. The study was a prospective, randomized, double-blinded, placebo-controlled, parallel-group trial. Eighty patients were included and divided into two groups: one group received tranexamic acid 30 mg/kg, and one group received placebo (0.9% NaCl) as a bolus injection before CPB. Postoperative blood loss was recorded for 16 h. Transfusions of blood products were recorded for the whole hospital stay. Transfusions of packed red cells were given when the hematocrit value was less than 20% during CPB and less than 25% after surgery. The patients in the tranexamic acid group had significantly less postoperative bleeding compared with the patients in the placebo group (mean [SD]) (475 [274] mL versus 713 [243] mL; P < 0.001). An effective inhibition of fibrinolysis was found in patients receiving tranexamic acid. Tranexamic acid reduces postoperative bleeding in coronary artery bypass grafting patients treated with aspirin until the day before surgery.

IMPLICATIONS

Continuation of aspirin medication until the day before coronary artery bypass grafting may increase postoperative bleeding. The administration of a single dose of tranexamic acid (30 mg/kg) immediately before cardiopulmonary bypass significantly reduced postoperative bleeding and inhibited fibrinolysis in these patients.

Hemorrhage after coronary artery bypass graft procedures

OBJECTIVES

To identify risk factors for excessive bleeding after coronary artery bypass graft (CABG) procedures and to quantify the outcomes related to this complication.

DESIGN

We conducted a case-control study to identify risk factors for hemorrhage following CABG surgery and a historical cohort study to quantify outcomes of hemorrhage.

SETTING

The cardiothoracic surgery service of a university hospital.

RESULTS

Factors associated with excessive blood loss were recent catheterization (odds ratio [OR] = 0.44; 95% confidence interval [CI95], 0.21 to 0.91); age older than 65 years (OR = 1.94; CI95, 0.96 to 3.93); bypass time of 150 minutes or more (OR = 2.91; CI95, 1.09 to 7.81); and postoperative platelet count of 160,000/mm3 or less (OR = 2.36; CI95, 1.06 to 5.22). The attributable cost of a postoperative hemorrhage was $3,866 (P = .0002) overall, $9,912 (P = .0001) for patients who required reoperation, and $3,316 (P = .03) for those treated medically. The median attributable postoperative length of stay was 1 day longer for cases than for controls (P = .011). Postoperatively, patients who hemorrhaged received significantly larger volumes of packed red blood cells (P < .0001), fresh frozen plasma (P < .0001), platelets (P < .0001), plasminate (P = .007), protamine sulfate (P < .0001), desmopressin acetate (P < .0001), and epsilon-aminocaproic acid (P < .0001) than did controls.

CONCLUSIONS

Age, duration of bypass, and postoperative platelet count were associated with excessive bleeding. Hemorrhage after CABG surgery significantly increased the length of stay and cost of care.

The effect of clopidogrel in combination with aspirin when given before coronary artery bypass grafting

OBJECTIVES

This study was designed to evaluate the effect of preoperative clopidogrel on coronary artery bypass graft surgery (CABG) outcomes.

BACKGROUND

Clopidogrel in combination with aspirin, given before percutaneous coronary intervention, has become the standard for stent thrombosis prevention. Some premedicated patients, however, are found to have surgical disease on angiography, and irreversible platelet inhibition becomes a concern for upcoming CABG.

METHODS

We prospectively studied 224 consecutive patients undergoing nonemergent first-time CABG, and compared those with preoperative clopidogrel exposure within seven days (n = 59) to those without exposure (n = 165).

RESULTS

The groups were comparable in age, gender, body surface area, preoperative hematocrit, preoperative prothrombin time and prior myocardial infarction. The clopidogrel group had higher 24-h mean chest tube output (1,224 ml vs. 840 ml, p = 0.001), and more transfusions of red blood cells (2.51 U vs. 1.74 U, p = 0.036), platelets (0.86 U vs. 0.24 U, p = 0.001) and fresh frozen plasma (0.68 U vs. 0.24 U, p = 0.015). Moreover, reoperation for bleeding was 10-fold higher in the clopidogrel group (6.8% vs. 0.6%, p = 0.018). The clopidogrel group also had less extubation within 8 h (54.2% vs. 75.8%, p = 0.002) and a trend towards less hospital discharge within five days (33.9% vs. 46.7%, p = 0.094).

CONCLUSIONS

Clopidogrel in combination with aspirin before CABG is associated with higher postoperative bleeding and morbidity. These findings raise concern regarding the routine administration of clopidogrel before anticipated coronary stent implantation.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Transfusion for coagulopathy after heart surgery: efficacy of laboratory studies

Limited information exists regarding transfusions specifically for coagulopathy following cardiac surgery and the value of pre- and postoperative coagulation tests. Procedures (86% coronary bypass, 7.5% valve, and 6.5% combined valve and bypass) on 478 patients were reviewed; 101 patients (21%) were transfused for postoperative coagulopathy. Compared to those not transfused, patients with coagulopathy were significantly older and smaller, and they had more combined valve procedures, emergency operations, and preoperative heparin treatment as well as longer crossclamp and bypass times. Three preoperative tests showed significant differences in the coagulopathy group: activated clotting time, partial thromboplastin time, and antithrombin-III level. Four postoperative tests showed significant differences between the groups: prothrombin time, partial thromboplastin time, fibrinogen level, and fibrin split products at 10 dilutions. Patient characteristics and pre- and postoperative testing can identify patients at high risk of transfusion specifically related to coagulopathy.

Determinants of operative mortality following primary coronary artery bypass surgery

BACKGROUND

The purpose of this study was to determine the factors which can help to predict operative mortality before performing the operation, and afterwards.

METHODS

The study population consisted of 504 patients (91 women and 413 men) who underwent primary isolated coronary artery bypass surgery from December 1997 to September 1999 by the same surgeon in a referral center in Tehran, Iran. Perioperative data were gathered and analyzed both in a univariate and multivariate model.

RESULTS

After the operation patients spent 7.3 +/- 4.0 days in hospital. The total operative morbidity was 20.5%. Arrhythmias were the most common complication, with atrial fibrillation as the predominant feature. Major complications of the operation were: low cardiac output (4.2%); prolonged ventilatory support (2.4%); hemorrhage and exploratory reoperation (2.0%); postoperative myocardial infarction (1.4%); postoperative renal failure in (1.4%); and postoperative cerebrovascular accident (0.8%). Operative mortality rate in this study was 2.98%. Factors associated with high operative mortality in univariate analysis were: recent myocardial infarction, low ejection fraction, non-elective operation, left main coronary artery disease and prolonged cardiopulmonary bypass time.

CONCLUSION

Our data suggest that prior to operation, operative mortality can be best predicted by urgency of operation and left ventricle ejection fraction. After performing the operation, prognostic factors include preoperative LVEF < or = 35%, non-elective operation, and prolonged cardiopulmonary bypass time. Further study is required to assess the generalization of our findings to Iranian patients.

Effect of clopidogrel on bleeding after coronary artery bypass surgery

OBJECTIVE

Platelet dysfunction is a common cause of bleeding after coronary artery bypass graft surgery. This study explores the effects of clopidogrel on bleeding complications after coronary artery bypass graft surgery.

DESIGN

Prospective observational study of patients undergoing coronary artery bypass graft.

SETTING

Tertiary care center.

PATIENTS

A total of 247 patients undergoing coronary artery bypass graft surgery.

INTERVENTIONS

None.

MEASUREMENTS

Primary end point was need for reexploration secondary to bleeding. Secondary end points included need for transfusion of blood products and chest tube output.

MAIN RESULTS

Eight (3.3%) of 247 patients required reexploration secondary to bleeding. Clopidogrel recipients had higher incidence of reexploration for bleeding (9.8 vs. 1.6, p =.01) with an odds ratio of 6.9 (95% confidence interval, 1.6-30). Clopidogrel also increased the percentage of patients receiving packed red blood cell transfusion (72.6 vs. 51.6%, p =.007), the number of packed red blood cell units (3 vs. 1.6, p =0.0004), and the number of cryoprecipitate units (2.4 vs. 1.2, p =.04) transfused after coronary artery bypass graft surgery. Among clopidogrel recipients, a trend for increased transfusion of platelet units (4.3 vs. 1.7, p =.05) and fresh frozen plasma units (1.1 vs. 0.6, p =.08) also was found.

CONCLUSIONS

Preoperative use of clopidogrel in combination with aspirin is associated with increased need for surgical reexploration as well as risk of packed red blood cell and cryoprecipitate transfusions after coronary artery bypass graft surgery.

Pharmacologic preservation of the hemostatic system during cardiac surgery

Bleeding after cardiac surgery remains a major potential problem. Numerous pharmacologic approaches to attenuating hemostatic system activation in cardiac surgery patients have been studied to further improve patient management. Therapeutic approaches studied include inhibiting thrombin generation or activation, preserving platelet function, and decreasing the need for transfusion of allogeneic blood products. Pharmacologic approaches to reduce bleeding and transfusion requirements in cardiac surgery patients are based on either preventing or reversing the defects associated with the CPB-induced coagulopathy. The increasing use of platelet inhibitors (clopidogrel and IIb/IIIa receptor antagonists) and new anticoagulants (low-molecular weight heparins, pentasaccharide, recombinant hirudin, bivalirudin, and argatroban) also pose interesting problems in managing cardiac surgery patients. Aprotinin and lysine analogues (epsilon-aminocaproic acid and tranexamic acid) have become mainstay therapeutic agents to prevent bleeding and the potential need for allogeneic transfusion. Newer therapies that are important to consider include the potential of recombinant activated factor VIIa as a therapy for refractory bleeding after cardiac surgery.

Mechanisms and attenuation of hemostatic activation during extracorporeal circulation

Patients undergoing cardiac surgery with cardiopulmonary bypass are at risk for excessive microvascular bleeding, which often leads to transfusion of allogeneic blood and blood components as well as reexploration in a smaller subset of patients. Excessive bleeding after cardiac surgery is generally related to a combination of several alterations in the hemostatic system pertaining to hemodilution, excessive activation of the hemostatic system, and potentially the use of newer, longer-acting antiplatelet or antithrombotic agents. Although several nonpharmacologic strategies have been proposed, this review summarizes the role of pharmacologic interventions as means to attenuate the alterations in the hemostatic system during CPB in an attempt to reduce excessive bleeding, transfusion, and reexploration. Specifically, agents that inhibit platelets, fibrinolysis, factor Xa and thrombin, as well as broad-spectrum agents, have been investigated with respect to their role in reducing consumption of clotting factors and better preservation of platelet function. Prophylactic administration of agents with antifibrinolytic, anticoagulant, and possibly antiinflammatory properties can decrease blood loss and transfusion. Although aprotinin seems to be the most effective blood conservation agent (which is most likely related to its broad-spectrum nature), agents with isolated antifibrinolytic properties may be as effective in low-risk patients. The ability to reduce blood product transfusions and to decrease operative times and reexploration rates favorably affects patient outcomes, availability of blood products, and overall health care costs.

An effective treatment of severe intractable bleeding after valve repair by one single dose of activated recombinant factor VII

IMPLICATIONS

The successful treatment with recombinant factor VIIa of a patient experiencing intractable bleeding after cardiac surgery is described.

Cardiac reoperation in the intensive care unit

BACKGROUND

At our institution, cardiac reoperations are routinely performed in the cardiac intensive care unit, as opposed to taking these patients back to the operating room. Our hypothesis was that reoperation in a cardiac intensive care unit does not increase sternal infection rate.

METHODS

A retrospective analysis was performed on 6,908 adult patients undergoing cardiac operation over a 9-year period. Excluding those in cardiac arrest, 340 (4.9%) patients underwent reoperation in the cardiac intensive care unit, of which 289 survived (85%).

RESULTS

Of the 289 patients who survived reoperation in the intensive care unit, 6 developed wound infections that required operative debridement (2.1%), which was not significantly different from those patients not requiring reoperation (1.9%, 121 of 6,497, p = 0.70). Hospital charges for a 2-hour reoperation in the intensive care unit and operating room are approximately $1,972/patient and $5,832/patient, respectively.

CONCLUSIONS

Reoperation in the intensive care unit does not increase wound infection rate compared to those without reoperation. Decreased charges, avoiding transport of potentially unstable patients, quicker time to intervention, and convenience are advantages of reoperation in an intensive care unit.

Management of bleeding and coagulopathy after heart surgery

Mechanisms of bleeding common to virtually all patients after heart surgery are platelet dysfunction, enhanced fibrinolysis, dilution of all components of the coagulation system, and the presence of heparin and protamine. The use of warfarin is increasing in patients with heart disease requiring surgery. The replenishment of vitamin K-dependent factors beyond a normal prothrombin time is not assessable, and the dilution associated with cardiopulmonary bypass can reach coagulopathic levels. Optimal preoperative preparation is required and intraoperative therapy initiated when indicated. Individualized heparin and protamine dosing, antifibrinolytic drug administration, minimization of blood loss and dilution, and minimal time on cardiopulmonary bypass are basic adjuncts to meticulous surgical hemostasis. When bleeding is observed in the postoperative period, a sequential assessment of the probable cause leads to initial therapy while laboratory test results are obtained. Ongoing assessment for hemodynamic instability caused by accumulated mediastinal blood is needed while managing the bleeding patient. A chest radiograph and transesophageal echocardiogram can be useful in diagnosing cardiac tamponade.

Platelet inhibitors and bleeding in cardiac surgical patients

A variety of measures may affect bleeding and transfusion requirements in abciximab-treated patients. These measures include recognition of the risk factors for increased bleeding and transfusion requirements, use of proper transfusion practices, conservation or increasing of red cell mass, appropriate heparin dosing and protamine reversal, reversal of anticoagulation, awareness of factors that affect activated clotting time (ACT), and appropriate anticoagulation for cardiopulmonary bypass.

Management approaches to platelet-related microvascular bleeding in cardiothoracic surgery

Patients undergoing cardiac surgery with cardiopulmonary bypass are at increased risk for microvascular bleeding that requires perioperative transfusion of blood components. Platelet-related defects have been shown to be the most important hemostatic abnormality in this setting. The exact association between preoperative use of potent platelet inhibitors and either bleeding or transfusion in patients undergoing cardiac surgical procedures is currently being defined. Laboratory evaluation of platelets and coagulation factors can facilitate the optimal administration of pharmacologic and transfusion-based therapy. However, their turnaround time makes laboratory-based methods impractical for concurrent management of surgical patients, which has led many investigators to study the role of point-of-care coagulation tests in this setting. Use of point-of-care tests of hemostatic function can optimize the management of excessive bleeding and reduce transfusion. Accordingly, point-of-care tests that assess platelet function may also identify patients at risk for acquired, platelet-related bleeding. The ability to reduce the unnecessary use of blood products and to decrease operative time or reexploration rates has important consequences for blood inventory, blood costs, and overall health care costs.

Current status of cardiac surgery in the abciximab-treated patient

BACKGROUND

Early surgical experience with abciximab and other glycoprotein (GP) IIb/IIIa receptor antagonists suggested a tendency toward excessive bleeding in patients treated with these agents. With increased use of GP IIb/IIIa inhibitors, cardiac surgeons have become aware of their hazards, as well as potential benefits, during and after cardiac surgery. Although published experience with the GP IIb/IIIa inhibitor abciximab is limited in scope, it suggests management guidelines for urgent coronary artery bypass grafting in abciximab-treated patients. As more urgent and elective surgical data are presented, a clearer picture of true bleeding risk will evolve.

METHODS

Two large retrospective studies examining reexploration for postoperative bleeding have identified risk factors, including advanced age, preoperative renal dysfunction, and operation/reoperation other than coronary artery bypass grafting. Other risk factors for transfusion requirement and increased morbidity and mortality are emergent operation, postoperative coagulopathy, and prolonged bypass time.

RESULTS

To minimize real and perceived bleeding effects, some authors have suggested delaying operation until platelet function has normalized, employing platelet transfusion in patients in whom delay is not possible, and exacting heparin management during cardiopulmonary bypass. Later reports have not noted increased bleeding when incorporating these modifications plus early platelet transfusion, if required. Further experience with abciximab removal and reversal may also ultimately reduce or eliminate excess transfusion requirements.

CONCLUSIONS

Surgeons should work closely with perfusionists and anesthesiologists on issues of heparinization in the abciximab-treated patient. The apparent paradox of preserved platelet numbers and depressed platelet function with abciximab use has led to speculation about a role for this agent and other shorter-acting GP IIb/IIIa inhibitors for "platelet anesthesia" during cardiopulmonary bypass. With careful surgical care, GP IIb/IIIa receptor antagonists can maintain and improve beneficial outcomes.

Does intraoperative hetastarch administration increase blood loss and transfusion requirements after cardiac surgery?

Hetastarch is used for intravascular volume expansion in cardiac surgery. Studies show conflicting effects of intraoperative hetastarch administration on postoperative bleeding. Hetastarch was routinely used for volume expansion during cardiovascular surgeries at our institution until its use was discontinued intraoperatively. We performed a retrospective chart review on patients undergoing primary coronary artery bypass grafting, valve repair or replacement requiring cardiopulmonary bypass (n = 444), 234 of which received intraoperative hetastarch and 210 did not. There was no difference in demographics, cardiac surgery, or cardiopulmonary bypass duration between the two groups. Blood loss for 0-4 h postoperatively was 377 +/- 244 mL in the group not receiving hetastarch compared with 515 +/- 336 mL in the group that received hetastarch (P < 0.001). For 0-24 h postoperatively, blood loss was 923 +/- 473 mL versus 1,283 +/- 686 mL in the absence and presence of hetastarch, respectively (P < 0.001). Allogeneic transfusion requirements (cryoprecipitate, fresh frozen plasma, and platelets) were larger in the hetastarch group (all P < 0.001). Nearly all (99%) patients in the hetastarch group received less than the manufacturer's recommended dose (20 mL/kg) of hetastarch.

IMPLICATIONS

Our large retrospective study suggests that intraoperative use of hetastarch in primary cardiac surgery with cardiopulmonary bypass may increase bleeding and transfusion requirements. A large prospective study is needed to determine if intraoperative administration of hetastarch should be avoided during cardiovascular surgery.

Pharmacological strategies to decrease excessive blood loss in cardiac surgery: a meta-analysis of clinically relevant endpoints

BACKGROUND

Excessive bleeding may complicate cardiac surgery, and is associated with increased morbidity and mortality. Pharmacological strategies to decrease perioperative bleeding have been investigated in a large number of controlled trials, most of which have shown a decrease in blood loss. However, most studies lacked sufficient power to detect a beneficial effect on clinically more relevant outcomes. We did a meta-analysis of all randomised, controlled trials of the three most frequently used pharmacological strategies to decrease perioperative blood loss (aprotinin, lysine analogues [aminocaproic acid and tranexamic acid], and desmopressin).

METHODS

Studies were included if they reported at least one clinically relevant outcome (mortality, rethoracotomy, proportion of patients receiving a transfusion, or perioperative myocardial infarction) in addition to perioperative blood loss. In addition, a separate meta-analysis was done for studies concerning complicated cardiac surgery.

FINDINGS

We identified 72 trials (8409 patients) that met the inclusion criteria. Treatment with aprotinin decreased mortality almost two-fold (odds ratio 0.55 [95% CI 0.34-0.90]) compared with placebo. Treatment with aprotinin and with lysine analogues decreased the frequency of surgical re-exploration (0.37 [0.25-0.55], and 0.44 [0.22-0.90], respectively). These two treatments also significantly decreased the proportion of patients receiving any allogeneic blood transfusion. By contrast, the use of desmopressin resulted in a small decrease in perioperative blood loss, but was not associated with a beneficial effect on other clinical outcomes. Aprotinin and lysine analogues did not increase the risk of perioperative myocardial infarction; however, desmopressin was associated with a 2.4-fold increase in the risk of this complication. Studies in patients undergoing complicated cardiac surgery showed similar results.

INTERPRETATION

Pharmacological strategies that decrease perioperative blood loss in cardiac surgery, in particular aprotinin and lysine analogues, also decrease mortality, the need for rethoracotomy, and the proportion of patients receiving a blood transfusion.

Trends in rates of reexploration for hemorrhage after coronary artery bypass surgery. Northern New England Cardiovascular Disease Study Group

BACKGROUND

While mortality rates associated with coronary artery bypass grafting (CABG) have been declining, it is unknown whether similar improvements in the rates of morbidity have been occurring. This study examines trends in reexploration rates for hemorrhage, one of the serious complications of CABG surgery. It also explores changes in patient characteristics and several surgeon practice patterns potentially related to bleeding risks that may explain variations in these rates.

METHODS

We performed a regional observational study of all of the 12,555 consecutive patients undergoing isolated CABG surgery in northern New England between 1992 and 1997. The rates of reexploration and patient characteristics were examined between two time intervals: period I (January 1, 1992 to June 1, 1994) and period II (June 1, 1995 to March 31, 1997). All of the region's 23 practicing surgeons responsible for these patients were surveyed to assess changes in practice patterns potentially related to bleeding risks.

RESULTS

The adjusted rates of reexploration for bleeding declined 46% between periods I and II (3.6% versus 2.0%, p < 0.001). All of the five cardiac centers in northern New England showed similar trends with adjusted risk reductions ranging from 32% to 48% between the two time periods. This decline occurred despite the patients in period II having higher percentages of risk factors for reexploration for bleeding compared to patients in period I. From the surgeon survey, the number of surgeons using antifibrinolytics markedly increased from period I to period II. More surgeons were also using preoperative aspirin and heparin up until the time of surgery in period II.

CONCLUSIONS

Similar to the rates of mortality, the rates of reexploration for bleeding following CABG surgery are substantially declining. This decrease in the reexploration rates occurred despite higher patient risks.

Optimal management of bleeding and transfusion in patients undergoing cardiac surgery

Patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) are at increased risk for excessive perioperative blood loss requiring transfusion of blood products. Point-of-care evaluation of platelets, coagulation factors, and fibrinogen can enable physicians to rapidly assess bleeding abnormalities, facilitate the optimal administration of pharmacological and transfusion-based therapy, and also identify patients with surgical bleeding. The ability to reduce the unnecessary use of blood products in this setting has important implications for emerging issues in blood inventory and blood costs. The ability to decrease surgical time, along with exploration rates, has important consequences for health care costs in an increasingly managed health care environment.

Is epsilon-aminocaproic acid as effective as aprotinin in reducing bleeding with cardiac surgery?: a meta-analysis

BACKGROUND

Although aprotinin is known to be effective in reducing postoperative hemorrhage after cardiac surgery, epsilon-aminocaproic acid, an alternative antifibrinolytic, is considerably less expensive. Because the results of 3 small randomized clinical trials comparing these 2 agents directly were inconclusive, we performed a meta-analysis to compare the relative effectiveness and adverse-effect profile of these 2 agents against placebo.

METHODS AND RESULTS

Data from 52 randomized clinical trials published between 1985 and 1998 involving the use of epsilon-aminocaproic acid (n=9) or aprotinin (n=46) in patients undergoing cardiac surgery were abstracted. Our primary outcomes were total blood loss, red blood cell transfusion rates and amounts, reexploration, stroke, myocardial infarction, and mortality. The meta-analysis revealed substantial reductions in total blood loss with epsilon-aminocaproic acid and low-dose aprotinin (each with a 35% reduction versus placebo, P<0.001) and high-dose aprotinin (53% reduction, P<0.001). There were identical reductions in total postoperative transfusions with epsilon-aminocaproic acid (61% reduction versus placebo, P<0. 010) and high-dose aprotinin (62% reduction, P<0.001). The proportion of patients transfused was similarly reduced with epsilon-aminocaproic acid (OR, 0.32; 95% CI, 0.15 to 0.69) and high-dose aprotinin (OR, 0.28; 0.22 to 0.37). Although both drugs reduced rates of reexploration to similar degrees, this effect was statistically significant only with high-dose aprotinin (OR, 0.39; 0. 24 to 0.61). epsilon-Aminocaproic acid and aprotinin had no effect on risks of postoperative myocardial infarction or overall mortality.

CONCLUSIONS

Because the 2 antifibrinolytic agents appear to have similar efficacies, the considerably less-expensive epsilon-aminocaproic acid may be preferred over aprotinin for reducing hemorrhage with cardiac surgery.