Variability in transfusion practice for coronary artery bypass surgery persists despite national consensus guidelines: a 24-institution study. Institutions of the Multicenter Study of Perioperative Ischemia Research Group

[Identification of risk factors for allogenic transfusion in cardiac surgery from an observational study]

OBJECTIVE

To determine perioperative variables for predicting allogenic transfusion in adult cardiac surgery.

STUDY DESIGN

Prospective study.

PATIENTS

We included 335 consecutive patients undergoing cardiac surgery between February and April 2001.

METHODS

Perioperative variables were prospectively collected in a database. For each patient who received transfusion, hemoglobin threshold for transfusion and total number of units of red cell concentrates were collected. Univariate and multivariate analysis were performed.

RESULTS

The two strategies for blood conservation which were predominantly used were aprotinin therapy (78%) and blood salvage from the extracorporeal circuit (68%). During perioperative period, 42% of patients [95% CI: 37-47%] received allogenic transfusion. The haemoglobin threshold for transfusion was 7.4 +/- 1.1 and 8.0 +/- 0.7 g x dl(-1) in operating room and in intensive care unit, respectively. On average, 3.4 +/- 2.7 units of red cell concentrates were transfused perioperatively per patient. Using multivariate analysis, perioperative allogenic transfusion was significantly associated with the following variables: preoperative haemoglobin level < 12 g x dl(-1) (odds ratio 8.9; p = 0.001), emergency procedure (odds = 3.7, p = 0.01), reoperation (odds ratio = 3.3; p = 0.002), chronic obstructive pulmonary disease (odds ratio = 2.5; p = 0.03) and complex surgery (odds ratio = 2.4; p = 0.01). The age, the gender, and body mass index were only independent risk factors by univariate analysis.

CONCLUSION

In despite of techniques to limit requirement of allogenic transfusion, a large proportion of cardiac surgical patients remains transfused. Independent risk factors of perioperative transfusion are haemoglobin level < 12 g x dl(-1), emergency procedure, reoperation, chronic obstructive pulmonary disease and complex surgery.

Factors affecting transfusion of fresh frozen plasma, platelets, and red blood cells during elective coronary artery bypass graft surgery

CONTEXT

The ability to predict the use of blood components during surgery will improve the blood bank's ability to provide efficient service.

OBJECTIVE

Develop prediction models using preoperative risk factors to assess blood component usage during elective coronary artery bypass graft surgery (CABG).

DESIGN

Eighty-three preoperative, multidimensional risk variables were evaluated for patients undergoing elective CABG-only surgery.

MAIN OUTCOMES MEASURES

The study endpoints included transfusion of fresh frozen plasma (FFP), platelets, and red blood cells (RBC). Multivariate logistic regression models were built to assess the predictors related to each of these endpoints.

SETTING

Department of Veterans Affairs (VA) health care system.

PATIENTS

Records for 3034 patients undergoing elective CABG-only procedures; 1033 patients received a blood component transfusion during CABG.

RESULTS

Previous heart surgery and decreased ejection fraction were significant predictors of transfusion for all blood components. Platelet count was predictive of platelet transfusion and FFP utilization. Baseline hemoglobin was a predictive factor for more than 2 units of RBC. Some significant hospital variation was noted beyond that predicted by patient risk factors alone.

CONCLUSIONS

Prediction models based on preoperative variables may facilitate blood component management for patients undergoing elective CABG. Algorithms are available to predict transfusion resources to assist blood banks in improving responsiveness to clinical needs. Predictors for use of each blood component may be identified prior to elective CABG for VA patients.

The predictive value of modified computerized thromboelastography and platelet function analysis for postoperative blood loss in routine cardiac surgery

Hemorrhage after cardiopulmonary bypass (CPB) remains a clinical problem. Point-of-care tests to identify hemostatic disturbances at the bedside are desirable. In the present study, we evaluated the predictive value of two point-of-care tests on postoperative bleeding after routine cardiac surgery. Prospectively, 255 consecutive patients were studied to compare the ability of modified thromboelastography (ROTEG) as well as a platelet function analyzer (PFA-100) to predict postoperative blood loss. Measurements were performed at three time points: preoperatively, during CPB, and after protamine administration with three modified thromboelastography and PFA tests. The best predictors of increased bleeding tendency were the tests performed after CPB. The angle alpha is the best predictor (area under the receiver operating characteristic curve 0.69) and, in combination with the adenosine diphosphate-PFA test, the predictive accuracy is enhanced (area under the receiver operating characteristic curve 0.73). The negative predictive value for the angle alpha is 82%, although the positive predictive value is small (41%). Thromboelastography is a better predictor than PFA. In routine cardiac surgery, impaired hemostasis as identified by point-of-care tests does not inevitably lead to hemorrhage postoperatively. However, patients with normal test results are unlikely to bleed for hemostatic reasons. Bleeding in these patients is probably caused surgically. The high negative predictive value supports early identification and targeted treatment of surgical bleeding by distinguishing it from a significant coagulopathy.

IMPLICATIONS

Thrombelastography and platelet function analysis in routine cardiac surgery demonstrate high negative predictive values for postoperative bleeding, which supports early identification and targeted treatment of surgical bleeding by distinguishing it from a significant coagulopathy. The positive predictive values are small. The best predictors are thrombelastography values obtained after cardiopulmonary bypass.

The predictive value of modified computerized thromboelastography and platelet function analysis for postoperative blood loss in routine cardiac surgery

Hemorrhage after cardiopulmonary bypass (CPB) remains a clinical problem. Point-of-care tests to identify hemostatic disturbances at the bedside are desirable. In the present study, we evaluated the predictive value of two point-of-care tests on postoperative bleeding after routine cardiac surgery. Prospectively, 255 consecutive patients were studied to compare the ability of modified thromboelastography (ROTEG) as well as a platelet function analyzer (PFA-100) to predict postoperative blood loss. Measurements were performed at three time points: preoperatively, during CPB, and after protamine administration with three modified thromboelastography and PFA tests. The best predictors of increased bleeding tendency were the tests performed after CPB. The angle alpha is the best predictor (area under the receiver operating characteristic curve 0.69) and, in combination with the adenosine diphosphate-PFA test, the predictive accuracy is enhanced (area under the receiver operating characteristic curve 0.73). The negative predictive value for the angle alpha is 82%, although the positive predictive value is small (41%). Thromboelastography is a better predictor than PFA. In routine cardiac surgery, impaired hemostasis as identified by point-of-care tests does not inevitably lead to hemorrhage postoperatively. However, patients with normal test results are unlikely to bleed for hemostatic reasons. Bleeding in these patients is probably caused surgically. The high negative predictive value supports early identification and targeted treatment of surgical bleeding by distinguishing it from a significant coagulopathy.

IMPLICATIONS

Thrombelastography and platelet function analysis in routine cardiac surgery demonstrate high negative predictive values for postoperative bleeding, which supports early identification and targeted treatment of surgical bleeding by distinguishing it from a significant coagulopathy. The positive predictive values are small. The best predictors are thrombelastography values obtained after cardiopulmonary bypass.

Agreements between the prothrombin times of blood treated In Vitro with heparinase during cardiopulmonary bypass (CPB) and blood sampled after CPB and systemic protamine

The prothrombin time (PT) is useful for identifying coagulation factor deficits after cardiopulmonary bypass (CPB). However, long processing times and the need for fresh frozen plasma (FFP) to be thawed cause delays in factor replacement. We hypothesized that, by treating with heparinase, blood sampled toward the end of CPB can provide PT results that help to determine the requirement for FFP after CPB. Laboratory delays can be eliminated with point-of-care monitors. We studied 158 adults undergoing nonemergent cardiac surgery. Blood taken before separation from CPB was mixed with heparinase, and PT was measured in the laboratory with a HemoTec timer. Agreements between these results and laboratory measurements of blood taken after systemic protamine were compared by using Bland and Altman plots with the threshold of +/-1.0 s. We found that the laboratory PT measurements during CPB versus after CPB were compara-ble, but the limits of agreement exceeded these thresholds. Similarly, there was unsatisfactory agreement between the HemoTec and laboratory PT results measured before, during, and after CPB. For each PT measured during CPB, the corresponding confidence interval for the postprotamine PT was calculated. During CPB, a laboratory PT of < or =16 s or > or =18 s suggests a > or =83% or > or =93% probability of not requiring or potentially requiring, respectively, FFP after CPB. We conclude that the majority of PT measurements obtained from blood taken before weaning from CPB and treated in vitro with heparinase was associated with a high probability of whether or not FFP would be needed after CPB.

IMPLICATIONS

Coagulation dysfunction after cardiopulmonary bypass may contribute to bleeding. Obtaining coagulation tests and fresh frozen plasma requires time and delays treatment in patients who need fresh frozen plasma. We have devised a technique to provide early estimation of postbypass coagulation status.

Safety and preliminary efficacy of hemoglobin raffimer for patients undergoing coronary artery bypass surgery

OBJECTIVE

To evaluate the safety and preliminary efficacy of escalating doses of hemoglobin raffimer (Hemolink) with intraoperative autologous blood donation for coronary artery bypass graft (CABG) surgery.

DESIGN

Randomized, controlled, single-blind phase II dose escalation trial.

SETTING

Multi-institutional university setting.

PARTICIPANTS

Adult patients (n = 60) undergoing elective CABG surgery.

INTERVENTIONS

After induction of anesthesia, autologous whole blood was collected to achieve a hemoglobin of 7 g/dL on cardiopulmonary bypass. Patients were randomized to receive either hemoglobin raffimer (treatment) or 6% hetastarch (control) in sequential escalating dose blocks of 250 mL, 500 mL, or 750 mL. After return of autologous blood, allogeneic red blood cells were transfused according to predetermined hemoglobin triggers.

MEASUREMENTS AND MAIN RESULTS

Safety parameters (vital signs, hematology, blood chemistry, coagulation, and adverse events) were monitored from randomization through week 4 postdischarge. Serious adverse events were distributed evenly between the 2 groups of patients. Elevated blood pressure was more frequent in the treatment group (16/28 mmHg v 9/32 mmHg, p = 0.036). In the group of 40 patients in the 750-mL dose block, 8 of the 18 treatment patients and 4 of the 22 control patients avoided allogeneic red blood cell transfusion (p = 0.093). Median volume of allogeneic red blood cells transfused was lower in treated subjects compared with controls (p = 0.042).

CONCLUSION

Hemoglobin raffimer is well tolerated and may be effective in reducing transfusion for patients undergoing CABG surgery. Although perioperative hypertension was more frequent in the treated patients, blood pressure management prevented serious adverse sequelae. Definitive evaluation of efficacy in a larger phase III trial is warranted.

Preoperative blood volume deficit influences blood transfusion requirements in females and males undergoing coronary bypass graft surgery

STUDY OBJECTIVE

To evaluate whether preoperative blood volume and postoperative blood loss influence blood transfusion in females and males undergoing coronary artery bypass graft (CABG) surgery.

DESIGN

Prospective study.

SETTING

Anesthesiology department of a teaching hospital.

PATIENTS

57 CABG patients (21 females and 36 males).

MEASUREMENTS

Blood volume was determined using the radioactivity dilution method. Preoperatively, each patient received intravenous (IV) injection of 1 mL Albumin I(131) tracer having 25 microcuries of radioactivity. Five-milliliter blood samples were collected at different intervals. From these samples, hematocrit (Hct) value, preoperative total blood volume, red blood cell (RBC) volume, and plasma volume were determined. Postoperatively, some consenting patients received another 1 mL dose of the tracer, and the postoperative blood volumes were determined. If a patient received a blood transfusion, the units of packed red blood cells (PRBCs), platelets, or fresh frozen plasma (FFP) transfused were recorded. For each patient we recorded the gender, age, weight, height, body surface area (BSA), preoperative Hct, duration of surgery, and discharge Hct.

RESULTS

Preoperatively, the mean total blood volume, RBC volume, and plasma volume, respectively, were 2095 mL/m(2), 631 mL/m(2), and 1,465 mL/m(2) in females; and 2,580 mL/m(2), 878 mL/m(2), and 1,702 mL/m(2) in males. The preoperative blood volumes were significantly lower (p < 0.01) in females than in males. There was no significant difference between males and females in the extent of blood loss during CABG. Intraoperatively, females received PRBC transfusion of 1.38 units, significantly more (p < 0.01) than the 0.39 units received by males. During the entire hospital stay, females received 4.33 units of PRBC, significantly more than (p < 0.02) the 1.33 units received by males. Significantly more (p < 0.01) females (12 of 21) received intraoperative PRBC transfusion than did males (6 of 36). Multiple logistic regression analysis of the data showed that PRBC transfusion was significantly correlated with the preoperative total blood volume and RBC volume.

CONCLUSION

The greater need for blood transfusion in females than in males during CABG is primarily attributable to significantly lower preoperative total blood volume and RBC volume in females.

Aspirin and mortality from coronary bypass surgery

BACKGROUND

There is no therapy known to reduce the risk of complications or death after coronary bypass surgery. Because platelet activation constitutes a pivotal mechanism for injury in patients with atherosclerosis, we assessed whether early treatment with aspirin could improve survival after coronary bypass surgery.

METHODS

At 70 centers in 17 countries, we prospectively studied 5065 patients undergoing coronary bypass surgery, of whom 5022 survived the first 48 hours after surgery. We gathered data on 7500 variables per patient and adjudicated outcomes centrally. The primary focus was to discern the relation between early aspirin use and fatal and nonfatal outcomes.

RESULTS

During hospitalization, 164 patients died (3.2 percent), and 812 others (16.0 percent) had nonfatal cardiac, cerebral, renal, or gastrointestinal ischemic complications. Among patients who received aspirin (up to 650 mg) within 48 hours after revascularization, subsequent mortality was 1.3 percent (40 of 2999 patients), as compared with 4.0 percent among those who did not receive aspirin during this period (81 of 2023, P<0.001). Aspirin therapy was associated with a 48 percent reduction in the incidence of myocardial infarction (2.8 percent vs. 5.4 percent, P<0.001), a 50 percent reduction in the incidence of stroke (1.3 percent vs. 2.6 percent, P=0.01), a 74 percent reduction in the incidence of renal failure (0.9 percent vs. 3.4 percent, P<0.001), and a 62 percent reduction in the incidence of bowel infarction (0.3 percent vs. 0.8 percent, P=0.01). Multivariate analysis showed that no other factor or medication was independently associated with reduced rates of these outcomes and that the risk of hemorrhage, gastritis, infection, or impaired wound healing was not increased with aspirin use (odds ratio for these adverse events, 0.63; 95 percent confidence interval, 0.54 to 0.74).

CONCLUSIONS

Early use of aspirin after coronary bypass surgery is safe and is associated with a reduced risk of death and ischemic complications involving the heart, brain, kidneys, and gastrointestinal tract.

Perflubron emulsion (AF0144) augments harvesting of autologous blood: a phase II study in cardiac surgery

OBJECTIVE

To assess tolerance and preliminary efficacy of a perfluorocarbon emulsion (AF0144) used with acute normovolemic hemodilution to reduce allogeneic blood transfusion for patients undergoing coronary artery bypass graft (CABG) surgery with cardiopulmonary bypass (CPB).

DESIGN

Controlled, single-blind, parallel-group phase II dose escalation trial.

SETTING

Single-institution university medical center.

PARTICIPANTS

Adult patients undergoing elective CABG surgery (n = 36).

INTERVENTIONS

A calculated volume of autologous whole blood was harvested for each patient with a target on-bypass hematocrit of 20% to 22%. Placebo, low-dose (1.8 g/kg) AF0144, or high-dose (2.7 g/kg) AF0144 was infused. During CPB, blood was transfused at protocol-defined triggers (hematocrit <15%, PvO(2) <30 mmHg, SvO(2) <60%). After CPB, all autologous whole blood was reinfused. Allogeneic red blood cells were transfused if a trigger was reached.

MEASUREMENTS AND MAIN RESULTS

Safety assessments (vital signs, hematology, blood chemistry, coagulation, and adverse events) were monitored through postoperative day 21. Efficacy endpoints included percentage of patients reaching a transfusion trigger and number of allogeneic units of red blood cells transfused. During CPB, <25% of subjects reached a transfusion trigger. During hospitalization, significantly fewer (p < 0.01) high-dose subjects (33%) reached a trigger than did control patients (91%). Allogeneic red blood cell transfusion did not differ significantly among groups. Safety assessments indicated AF0144 was well tolerated.

CONCLUSION

The data suggest that AF0144 when used with acute normovolemic hemodilution is well tolerated and may be effective when used to enhance oxygen delivery for patients undergoing CABG surgery. Confirmation of safety and efficacy in a larger phase III clinical trial is warranted.

Survey on transfusion practices of pediatric intensivists

OBJECTIVE

To describe the red blood cell transfusion practices of pediatric intensivists.

DESIGN

Cross-sectional self-administered survey.

SETTING

Pediatric intensive care units.

PATIENTS

Academic pediatric intensivists.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Scenario-based survey among English- or French-speaking intensivists from Canada, France, Belgium, or Switzerland, working in tertiary-care pediatric intensive care units. Respondents were asked to report their decisions regarding transfusion practice with respect to four scenarios: cases of bronchiolitis, septic shock, trauma, and the postoperative care of a patient with Fallot's tetrad. The response rate was 71% (163 of 230). The overall baseline hemoglobin transfusion threshold that would have prompted intensivists to transfuse a patient ranged from 7 to 13 g/dL (70-130 g/L) within almost all scenarios. There was a significant difference between scenarios of the average baseline hemoglobin transfusion thresholds (p < .0001). A low Pao2, a high blood lactate concentration, a high Pediatric Risk of Mortality score, active gastric bleeding, emergency surgery, and age (2 wks) were important determinants of red blood cell transfusion, whereas none of the respondents' personal characteristics were. The average volume of packed red blood cells transfused in the four scenarios did not differ significantly.

CONCLUSIONS

This survey documented a significant variation in transfusion practice patterns among pediatric critical care practitioners with respect to the threshold hemoglobin concentration for red blood cell transfusion. The volume of packed red blood cells given was not adjusted to the hemoglobin concentration.

Mechanisms behind operating room blood transfusions in coronary artery bypass graft surgery patients with insignificant bleeding

OBJECTIVE

To investigate situations in cardiac surgery when transfusions are sometimes used for indications other than to compensate for surgical bleeding.

DESIGN

Retrospective study.

SETTING

Cardiac surgery unit at a university teaching hospital.

PARTICIPANTS

Patients scheduled for coronary artery bypass graft surgery (n = 2,469).

INTERVENTIONS

A subgroup of patients with surgical bleeding of < or = 400 mL (n = 982) was selected to identify mechanisms leading to perioperative erythrocyte transfusion.

MEASUREMENTS AND MAIN RESULTS

Bleeding of >400 mL triggered transfusion. At less than this bleeding volume, other indications were noted: unstable angina, use of blood cardioplegia, and bad surgical outcome, such as inotropic support. After exclusion of these predictors and anemic patients, the strongest predictors were female gender (p < 0.001), weight < or = 70 kg (p < 0.001), cardiopulmonary bypass (CPB) time > or = 90 minutes (p = 0.002), CPB cooling < or = 32 degrees C (p = 0.038), and advanced age (p < 0.001). Results from a more detailed study of medical records showed that within its normal concentration range, the operating room-transfused patients had lower hemoglobin levels. When followed postoperatively in the intensive care unit and ward, these patients continued to receive more transfusions (p < 0.05) even though their bleeding in the intensive care unit did not differ from the control subjects.

CONCLUSION

Some patients are transfused because of institutional bias of an anticipated need rather than for true surgical bleeding. A concern of hemodilution from standard CPB circuits suggests a possible advantage with low-priming volume for smaller adult female patients.

Blood Transfusion Issues in the Critically Ill

Anemia is a common clinical problem seen in the critically ill and results in a large RBC transfusion requirement for these patients. The view that RBC transfusion is risk-free is no longer tenable today. There is the accumulating evidence that allogeneic blood transfusion is immunosuppressive. More reently, attention has focused on the age of RBCs transfused. Transfused RBCs, especially during the time period immeditely following transfusion, are not normal. The duration of RBC storage may be an important determinant of the efficacy of RBCs as oxygen carriers as well as a determinant of transusion related morbidity. Adding to the controversy about risk/benefit ratio for RBC transfusion are recent data showing that an aggressive RBC transfusion strategy may decrease the likelihood of survival in selected subpopulations of critically ill adults. The optimal hematocrit for the ICU patient remains to be determined. It seems clear that hemoglobin levels falling significantly below the “10/30” threshold can be tolerated. However, it is not clear that this is applicable to the critically ill ICU patient population. Therefore, while hemoglobin levels in the 7-10 mg/dL range are well tolerated in the “stable” “nontressed” patient, this range might not be optimal for the critcally ill patient. Conservative transfusion thresholds as well as strategies to minimize loss of blood and increase the producion of RBCs are important in the management of critically ill patients.

Polymerized bovine hemoglobin solution as a replacement for allogeneic red blood cell transfusion after cardiac surgery: results of a randomized, double-blind trial

BACKGROUND

Blood loss leading to reduced oxygen-carrying capacity is usually treated with red blood cell transfusions. This study examined the hypothesis that a hemoglobin-based oxygen-carrying solution can serve as an initial alternative to red blood cell transfusion.

METHODS

In a randomized, double-blind efficacy trial of HBOC-201, a total of 98 patients undergoing cardiac surgery and requiring transfusion were randomly assigned to receive either red blood cell units or HBOC-201 (Hemopure; Biopure Corporation, Cambridge, Mass) for the first three postoperative transfusions. Patients were monitored before and after transfusion, at discharge, and at 3 to 4 weeks after the operation for subsequent red blood cell use, hemodynamics, and clinical laboratory parameters.

RESULTS

The use of HBOC-201 eliminated the need for red blood cell transfusions in 34% of cases (95% confidence interval 21%-49%). Patients in the HBOC group received a mean of 1.72 subsequent units of red blood cells; those who received red blood cells only received a mean of 2.19 subsequent units (P =.05). Hematocrit values were transiently lower in the HBOC group but were similar in the two groups at discharge and follow-up. Oxygen extraction was greater in the HBOC group (P =.05). Mean increases in blood pressure were greater in the HBOC group, but not significantly so.

CONCLUSION

HBOC-201 may be an initial alternative to red blood cell transfusions for patients with moderate anemia after cardiac surgery. In a third of cases, HBOC-201 eliminated the need for red blood cell transfusion, although substantial doses were needed to produce this modest degree of blood conservation.

Retrograde autologous priming of the cardiopulmonary bypass circuit reduces blood transfusion after coronary artery surgery

BACKGROUND

Hemodilution occurring with cardiopulmonary bypass imposes a risk for blood transfusion. Autologous priming of the cardiopulmonary bypass circuit at the initiation of bypass partially replaces the priming solution with autologous blood. We examined the efficacy of autologous priming of the circuit in reducing blood transfusion.

METHODS

One hundred and four patients were entered into a prospective, randomized, controlled study. Initiation of cardiopulmonary bypass was with or without autologous priming.

RESULTS

With autologous priming, a mean volume of 808.8 +/- 159.3 mL of priming solution was replaced with autologous blood. This allowed a higher hematocrit value on admission to the intensive care unit and at discharge from hospital. In all, 49% of the control group required a blood transfusion compared with 17% from the autologous priming group (p = 0.0007). The mean volume of blood transfused was 277.6 +/- 363.8 mL in the control group compared with 70.1 +/- 173.5 mL in the autologous priming group (p = 0.0005).

CONCLUSIONS

Retrograde autologous priming of the bypass circuit reduces homologous blood transfusion owing to the reduction in bypass circuit priming volume.

High or low hematocrits during cardiopulmonary bypass for patients undergoing coronary artery bypass graft surgery? An evidence-based approach to the question

We have observed an inverse relationship between a CPB Hct <20% and the need for cardiac support and hospital mortality. These data call for an aggressive and concerted effort to avoid a CPB Hct of <20%. The focus should be directed at women and small men since this subset of patients are most likely to experience low CPB Hct. A comprehensive, multimodality blood-conservation plan that involves the use of erythropoietin, aprotinin, preoperative autologous donation, shed blood reinfusion, and minimal phlebotomy for blood testing was proposed by Rosengart and colleagues based on their experience in caring for 50 Jehovah's Witness patients. Efforts to conserve blood and ensure hemostasis should cover the entire spectrum of care, including preoperative phlebotomy (for blood tests), diagnostic and interventional procedures, and intraoperative and postoperative care. Further work is needed to understand the mechanism for the relationship between low Hct and adverse outcomes. Each open-heart center should consider the Hct question carefully, examining both the published literature and their own results related to CPB Hct and patient outcomes.

Practical management of anticoagulation, bleeding and blood product support for cardiac surgery part two: Transfusion issues

We summarise recent advances in transfusion medicine applicable to cardiac surgery and cardiac transplantation. It is important that clinicians know the risks of blood transfusion in Australia. They should also be aware of the different types of transfusion reaction so that there is early recognition and investigation. Blood conservation strategies including acceptance of normovolaemic anaemia in clinically stable patients are important in reducing the requirement for red cell transfusion. Cytomegalovirus (CMV) seronegative blood products are recommended for heart transplant recipients with no evidence of prior CMV infection. Leucodepletion of units of unknown CMV status reduces the risk of CMV infection and are an acceptable alternative when seronegative units are unavailable. Leucodepletion of cellular blood products has been shown to reduce infection rates postoperatively in a large trial involving cardiac surgical patients. Further studies are needed to confirm this promising finding. Irradiation of blood products eliminates the risk of transfusion-associated graft versus host disease. Routine preoperative screening for cold agglutinins is no longer recommended.

Erythropoietin therapy versus red cell transfusion

Erythropoietin therapy was approved for use as a blood conservation intervention beginning in 1989 for patients with medical anemia and in 1997 for surgical patients. The adoption of this strategy has been rapid in some settings (such as renal failure patients), progressive in others ( eg, cancer patients), and slow in others (surgery patients, for instance). At the same time, the risks of blood transfusion have declined substantially whereas the costs of blood transfusion have increased significantly. The evolution of new techniques such as acute normovolemic hemodilution (ANH) and the novel erythropoiesis-stimulating protein (NESP) bring new options to allogeneic blood transfusion. Erythropoietin therapy, with or without autologous blood procurement, is undergoing new scrutiny as an alternative to blood transfusion. This is not only because of traditional concerns regarding blood risks but because of new blood inventory and cost considerations.

Quality care outcomes in cardiac surgery: the role of evidence-based practice

An internal database and research methods were used to evaluate the impact of clopidogrel on cardiac surgical bleeding. This quality improvement initiative, led by the clinical nurse specialist, showed that preoperative exposure to clopidogrel was associated with significant increases in chest tube output, blood product use, and reoperation for bleeding rates that were 10-fold higher than for control patients (0.85% versus 8.3%, P = 0.027). Acute care costs averaged $2,680 more for patients who received clopidogrel (P = 0.1936). After implementation of an interdepartmental clinical practice guideline, preoperative exposure to clopidogrel dropped from 39% to 6.3% (P = 0.0000). This drop was accompanied by reductions in chest tube output, blood product use, and bleeding complications, with improved achievement of clinical benchmarks. The availability of internal evidence to support achievement of best practices was an essential factor in the implementation of this interdepartmental change. Comprehensive database systems and advanced practice nurses are highlighted as essential components of evidence-based programs.

Advances in cardiac surgical transfusion practices during the 1990s in a Finnish university hospital

BACKGROUND AND OBJECTIVES

Recent transfusion practices in coronary artery bypass (CABG) operations in a Finnish university hospital were evaluated, utilizing the data stored automatically in hospital registers.

MATERIALS AND METHODS

The register-based transfusion data on all 2363 CABG patients operated on during a 2.5-year period, from 1997 to 1999, were analysed and compared with a review of surgical transfusion practices in Finland from 1993 to 1994.

RESULTS

The rate of allogeneic transfusion showed a decrease from 76% in 1993-94 to 48% in the time-period January to June 1999, and the mean number of donor exposures decreased from 3.3 to 2.0 units per patient. The mean blood product purchase costs per patient almost halved from 1993-94 to 1997-99.

CONCLUSION

Hospital registers provide a good means for prompt evaluation and reporting of large-scale transfusion data. Since 1993, transfusion rates and costs in CABG operations have decreased markedly. Further development of transfusion registers is warranted.

[Transfusion of fresh frozen plasma (FFP): audit of prescriptions]

OBJECTIVE

To review fresh frozen plasma (FFP) prescriptions and compare their validity to the legal french guidelines (law of the 12/03/91).

STUDY DESIGN

Assessment of all prescriptions has been carried out by a multidisciplinary committee.

PATIENTS

All the adults transfused with FFP over one year in a teaching hospital.

METHODS

Following each head of department's agreement and following a written notice to all prescribers within the hospital to inform them of the undergoing study and its methodological validation by the board of quality experts, each delivery of FFP was followed by a questionnaire addressed to the prescriber. A board of experts then assessed the significance of the prescription in accordance with the legal requirements after reviewing each medical file.

RESULTS

144 prescriptions to 89 patients were assessed: 23% were judged inappropriate by the experts and 6% did not respect the law. The inappropriate transfusions distribute as follows: intensive care patients (73% of which 80% in multiple organ failure (MOF) and 20% in haemorrhagic shock), cirrhotic patients (12%), patients treated with vitamin K antagonists (12%), obstetric patients (3%). Nine percent of the appropriate transfusions were judged in insufficient volume. The hospital mortality rate was 48%. Among prescribers, 59% were not aware of the law.

CONCLUSION

A significant proportion of FFP transfusions is inappropriate. This study, which is the first step of a quality assurance program, will be followed by local recommendations for clinical practice. The current standards of prescribing FFP are more restrictive than those defined in the legal french guidelines.

A multivariable model for predicting the need for blood transfusion in patients undergoing first-time elective coronary bypass graft surgery

BACKGROUND

The incidence of blood transfusion in coronary artery bypass graft (CABG) surgery remains high. Preoperative identification of those at high risk for requiring blood will allow for the cost-effective use of some blood conservation modalities. Multivariable analysis techniques were used in this study to develop a prediction rule for such a purpose.

STUDY DESIGN AND METHODS

Data were prospectively collected for all patients undergoing elective first-time CABG surgery from January 1997 to September 1998 at a tertiary-care teaching hospital (n = 1007). The prediction rule was developed on the first two-thirds of the sample by using logistic regression methods to examine the relationship of patient demographics, comorbidities, and preoperative Hb with perioperative blood transfusion. The remaining one-third of the sample was used to validate the rule.

RESULTS

The transfusion rate was 29.4 percent. The prediction rule included preoperative Hb (g/dL, OR 0.928, p<0.0001), weight (kg, OR 0.938, p<0.0001), age (years, OR 1.037, p<0.01), and sex (male/female, OR 0.493, p<0.01); receiver operating characteristic = 0.86. When externally validated, the rule had a sensitivity of 82.1 percent and a specificity of 63.6 percent (at a selected probability cutoff).

CONCLUSION

A simple and valid prediction rule is developed for predicting the risk of blood transfusion in patients undergoing first-time elective CABG surgery.

A standardized multidisciplinary approach reduces the use of allogeneic blood products in patients undergoing cardiac surgery

PURPOSE

Individual and institutional practices remain an independent predictor factor for allogeneic blood transfusion. Application of a standardized multidisciplinary transfusion strategy should reduce the use of allogeneic blood transfusion in major surgical patients.

METHODS

This prospective non randomized observational study evaluated the effects of a standardized multidisciplinary transfusion strategy on allogeneic blood products exposure in patients undergoing non-emergent cardiac surgery. The developed strategy involved a standardized blood conservation program and a multidisciplinary allogeneic blood transfusion policy based mainly on clinical judgement, not only on a specific hemoglobin concentration. Data obtained in a first group including patients operated from September 1997 to August 1998 (Group pre: n=321), when the transfusion strategy was progressively developed, were compared to those obtained in a second group, including patients operated from September 1998 to August 1999 (Group post: n=315) when the transfusion strategy was applied uniformly.

RESULTS

Patient populations and surgical procedures were similar. Patients in Group post underwent acute normovolemic hemodilution more frequently, had a higher core temperature at arrival in the intensive care unit and presented lower postoperative blood losses at day one. Three hundred forty units of packed red blood cells were transfused in 33% of the patients in Group pre whereas 161 units were transfused in 18% of the patients in Group post (P <0.001). Pre- and postoperative hemoglobin concentrations, mortality and morbidity were not different among groups.

CONCLUSION

Development of a standardized multidisciplinary transfusion strategy markedly reduced the exposure of cardiac surgery patients to allogeneic blood.

Hemostatic Abnormalities in Cardiopulmonary Bypass: Pathophysiologic and Transfusion Considerations

Cardiac surgical procedures typically use cardiopulmo nary bypass (CPB), a technique that diverts blood from the heart and lungs, where it is oxygenated and pumped back into the circulation. CPB is associated with significant pathophysiologic changes leading to an increased bleeding risk. Bleeding during CPB occurs for multiple reasons; the primary reason is the expo sure of blood to the material components of the CPB system, with intense systemic coagulation and platelet, fibrinolytic, and endothelial activation. To counteract the coagulation activation, extremely high levels of heparin anticoagulation are required to prevent sys temic thrombosis. Thrombin generation through tissue factor pathway activation is now thought to be the predominant mechanism of coagulation activation in CPB. The stimulus for tissue factor exposure to blood is thought to be a systemic activation of tissue factor on monocytes and endothelial cells caused by comple ment activation by the CPB materials and circulating inflammatory mediators. Despite improvements in the CPB system, surgical techniques, and blood conserva tion methods, the demand for blood in such procedures remains sustantial. Optimal blood use can be achieved by combining blood conservation measures with the transfusion of blood components according to strict guidelines. Blood is a limited resource and must be used wisely and cautiously. The risks and costs associ ated with transfusion are compelling reasons to mini mize unnecessary exposure to blood. However, the bene fits of transfusion are well established, and the risks are reasonably low. New developments in the surfaces of the CPB system, use of established and new protease inhibitors, and new blood conservation measures offer promise in decreasing the bleeding risk associated with CPB.

Intraoperative plateletpheresis and autologous platelet gel do not reduce chest tube drainage or allogeneic blood transfusion after reoperative coronary artery bypass graft

Platelet-rich plasma (PRP) is postulated to decrease postoperative mediastinal chest tube drainage (MCTD) and allogeneic blood transfusions (ABT) after surgery with cardiopulmonary bypass. However, recent metaanalysis of the literature reveals that few good quality (therapeutic yield) trials that show a benefit have been published. The potential hemodynamic instability caused by plateletpheresis has not been emphasized. We studied the effect of plateletpheresis on MCTD, ABT, and hemodynamic stability in reoperative coronary artery bypass graft patients, a group perceived to be at high risk for ABT. Ninety patients were randomly assigned to Pheresis or Control groups. epsilon-Aminocaproic acid was given to all patients. Hemodynamic instability was assessed by degree of volume and inotrope resuscitation required. Part of the sequestered platelet volume was used to make autologous platelet gel, which was applied as a wound sealant. Mean pheresis yield was 30% +/- 7% of the circulating platelet mass or 6.4 +/- 2.2 allogeneic platelet unit equivalents. Total MCTD did not differ between the groups. There were no differences in mean packed red blood cell, platelet, and plasma transfusion rates. Overall, 52% of the Pheresis group received ABT, versus 55% of the Control group. Fifty-three percent of the Pheresis group patients exhibited significant hemodynamic instability, versus 27% of the Control group (P < 0.05). This study was unable to show any reduction in MCTD or ABT, although the plateletpheresis technique may offset platelet dysfunction caused by aspirin or increased blood exposure to nonbiologic surfaces, or it may compensate for lack of antifibrinolytic use. The significantly increased incidence of hemodynamic instability in the Pheresis group means that the risk/benefit ratio must be determined for individual cardiac surgical units.

A practical approach to achieving bloodless surgery

The term bloodless surgery refers to the practice of performing surgical procedures without the use of allogenic blood and avoiding the use of stored blood, including autologous blood, entirely. This article reviews the scientific and clinical literature regarding bloodless surgery and describes the application of a full-service, bloodless program within a community hospital.

Evaluation of oxygen extraction ratio as a physiologic transfusion trigger in coronary artery bypass graft surgery patients

BACKGROUND

Approximately 20 percent of all allogeneic blood transfusions are administered in connection with coronary artery bypass graft (CABG) operations. Transfusion practices vary across the country. The whole-body oxygen extraction ratio (O2 ER) reflects the adequacy of the patient's response to acute normovolemic anemia with an O2 ER of approximately 50 percent being shown to be an appropriate transfusion trigger. The present study monitored the O2 ER in patients undergoing CABG and determined if transfusion practices would have been different if an O2 ER > or = 45 percent were used as a transfusion trigger.

STUDY DESIGN AND METHODS

Seventy patients with a postoperative Hct < = 25 percent were the test subjects. Arterial and mixed venous contents were determined before the operation, in the intensive care unit after the operation, and 12 hours after the operation.

RESULTS

There were no deaths. Forty-one patients received allogeneic transfusion. These patients were older, weighed less, and had a preoperative Hct lower than the nontransfused patients. There were no significant differences between transfused and nontransfused patients with respect to postoperative Hct (21.0 +/- 0.4 vs. 22.2 +/- 0.4), cardiac index (2.5 +/- 0.1 vs. 2.7 +/- 0.1), O2 delivery (6.4 +/- 0.3 vs. 6.7 +/- 0.3), O2 consumption (2.5 +/- 0.1 vs. 2.5 +/- 0.1), and O2 ER (38.3 +/- 1.7 vs. 37.5 +/- 1.5). In the transfusion group, 7 of 21 patients had a postoperative O2 ER > or = 45 percent, while 3 of 35 in the nontransfused group had that result.

CONCLUSION

The use of O2 ER as a transfusion trigger as part of a transfusion algorithm could lead to a reduction in allogeneic blood transfusion.

On-site coagulation monitoring does not affect hemostatic outcome after cardiac surgery

BACKGROUND

Rapid coagulation tests are now available for monitoring of bleeding patients after cardiac surgery. As inappropriate blood use in these patients may be due to lack of timely coagulation data, we studied the effect of an algorithm with on-line coagulation monitoring on transfusions in these patients.

METHODS

Prospectively, patients bleeding (>1.5 ml kg(-1) 15 min(-1)) after cardiac surgery were randomly assigned to two groups: in group A (n=28), hemostatic treatment during the immediate recovery period (1 h after surgery) was based on an algorithm with on-site hemostasis monitoring, whereas during the same period group B patients (n=30) were managed solely according to the clinician's judgement; laboratory tests other than activated clotting time after heparin neutralization were prohibited.

RESULTS

Cumulative chest tube drainage up to 16 h and total transfusion requirements did not differ between the groups. Using a platelet transfusion trigger of 100x10(9)/l, significantly more patients received platelets during the immediate recovery period in the algorithm group than in the control group (14 vs. 3 patients, P=0.001). Desmopressin acetate was administered more often in group A than in group B (8 vs. 2 patients, P=0.04).

CONCLUSIONS

Algorithm-based therapy increased utilization of hemostatic interventions during the immediate recovery period without any obvious benefit to the hemostatic outcome. Re-evaluation of the platelet transfusion trigger seems warranted.

Transfusion medicine : support of patients undergoing cardiac surgery

There is still no alternative that is as effective or as well tolerated as blood; nevertheless, the search for ways to conserve, and even eliminate blood transfusion, continues. Based on hemoglobin levels, practice guidelines for the use of perioperative transfusion of red blood cells in patients undergoing coronary artery bypass grafting have been formulated by the National Institutes of Health and the American Society of Anesthesiologists. However, it has been argued that more physiologic indicators of adequacy of oxygen delivery should be used to assess the need for blood transfusion. Methods used for conserving blood during surgery include autologous blood donation, acute normovolemic hemodilution and intra- and postoperative blood recovery and reinfusion. The guidelines for the use of autologous blood transfusion are controversial and it does not appear to be cost effective compared with allogeneic blood transfusion in patients undergoing cardiac surgery. Similarly, the cost effectiveness of intra- and postoperative blood recovery and reinfusion need further evaluation. Treatment with recombinant human erythropoietin (rhEPO) remains unapproved in the US for patients undergoing cardiac or vascular surgery, but it is a valuable adjunct in Jehovah's Witness patients, for whom blood is unacceptable. The characterization of darbepoetin alfa, a novel erythropoiesis stimulating protein with a 3-fold greater plasma elimination half-life compared with rhEPO, is an important advance in this field. Darbepoetin alfa appears to be effective in treating the anemia in patients with renal failure or cancer and trials in patients with surgical anemia are planned. Desmopressin has been used to effectively reduce intraoperative blood loss. Topical agents to prevent blood loss, such as fibrin glue and fibrin gel, and agents that alter platelet function, such as aspirin (acetylsalicylic acid) or dipyridamole, need further evaluation in patients undergoing cardiac surgery. Aprotinin has been shown to preserve hemostasis and reduce allogeneic blood exposure to a greater extent than the antifibrinolytic agents tranexamic acid and aminocaproic acid. Controlled clinical trials comparing the costs of these agents with clinical outcomes, along with tolerability profiles in patients at risk for substantial perioperative bleeding are needed.

Reducing red blood cell transfusion in elective surgical patients: the role of audit and practice guidelines

In 1996, we prospectively audited peri-operative transfusion practice in elective surgical patients over a 3-month period. Two-unit transfusions represented 60% of all transfusions. Haemoglobin was measured infrequently prior to transfusion and the main 'trigger' for transfusion was an estimated blood loss in excess of 500 ml. Transfusion guidelines that required the haemoglobin level to be measured immediately before transfusion were introduced. The audit was repeated in 1998; transfusion 'triggers' and the number of transfusions for the two periods were compared. In the second audit, the total number of transfusions decreased by 43%. The mean estimated blood loss associated with a 2-unit transfusion had increased from 608 (373) ml to 1320 (644) ml (p < 0.01) and the estimated haemoglobin concentration after transfusion had decreased from 12.4 (1.8) g.dl-1 to 9.9 (2.4) g.dl-1 (p < 0.01). These results suggest that transfusion guidelines can have a significant impact on clinical practice.

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.

Transfusions in patients undergoing cardiac surgery with autologous blood

PURPOSE

Determinants of allogeneic blood use in cardiac surgery include preoperative factors such as female sex, age, body weight, hematocrit and red cell volume. We verified if these variables also predicted the need for allogeneic transfusions when autologous blood is predonated.

METHODS

Demographic and intraoperative variables, hemoglobin concentrations and transfusion requirements in patients undergoing cardiopulmonary bypass with autologous blood predonation were reviewed. Multivariate logistic regression and RECPAM tree-growing analyses were applied to identify the preoperative predictors of allogeneic transfusion in these patients.

RESULTS

Data from 230 patients included in our autologous blood program between 1995 and 1998 were analysed. Patients undergoing complex/reoperative surgical procedures and patients over age 64yr with a low red cell volume (<2070ml) undergoing simple procedures were more likely to require allogeneic red cells. Younger patients with a low red cell volume undergoing simple procedures carried an intermediate risk. Allogeneic transfusion was avoided in 95% of patients undergoing simple procedures when red cell volume > or = 2070ml.

CONCLUSIONS

In our institution, complex/reoperative surgery, low red cell volume and increased age are the main factors associated with the need for allogeneic red cell transfusion despite autologous blood predonation. Knowledge of the factors that limit the effectiveness of predonation with respect to allogeneic blood exposure should help clinicians decide which cardiac surgical patients should be included in autologous blood programs.

Cost-effectiveness of epoetin and autologous blood donationin reducing allogeneic blood transfusions incoronary artery bypass graft surgery

BACKGROUND

Coronary artery bypass graft (CABG) surgery accounts for a substantial portion of all allogeneic units of blood transfused. Drugs and autologous blood donation (ABD) are alternative or adjunctive methods for reducing complications and costs induced by allogeneic blood transfusions. Recombinant human erythropoietin (epoetin) has the potential to decrease perioperative need for allogeneic blood during CABG, but its high cost calls for a careful economic evaluation before it can be recommended for widespread use.

STUDY DESIGN AND METHODS

A decision tree was used to compare a hypothetical strategy of no epoetin with one in which epoetin was utilized to control blood transfusion needs in CABG; each strategy was tested with and without ABD. The impact of these strategies on both the quality-adjusted life years (QALYs) and costs ($US) was calculated.

RESULTS

Using epoetin alone and with ABD, respectively, avoided the transfusion of 0.61 and 1.35 units of allogeneic blood per patient and saved 0.000086 and 0.000146 QALYs per patient. This made cost-effectiveness (CE) higher than $7 million and $5 million for each QALY saved, respectively. ABD alone cost more than $1 million per QALY saved. If the risk of bacterial infections following allogeneic transfusions was included in the model, epoetin alone cost $6288 per QALY saved, while ABD, both alone and with epoetin, saved money.

CONCLUSION

On the basis of the existing evidence, neither of the blood-saving strategies modeled was a cost-effective means of avoiding the deleterious health effects of perioperative blood transfusions in CABG. However, if allogeneic blood-related infections were to be considered, both ABD and epoetin would be acceptable interventions.

Institutional variability in red blood cell conservation practices for coronary artery bypass graft surgery. Institutions of the MultiCenter Study of Perioperative Ischemia Research Group

OBJECTIVE

To assess whether substantial institutional variability exists in red blood cell conservation practices associated with coronary artery bypass graft (CABG) surgery.

DESIGN

Prospective, randomized patient enrollment and data collection.

SETTING

Twenty-four U.S. academic institutions participating in the Multicenter Study of Perioperative Ischemia.

PARTICIPANTS

A well-defined subset of primary CABG surgery patients (n = 713) expected to be at low risk for bleeding and exposure to allogeneic transfusion.

INTERVENTIONS

None (observational study).

MEASUREMENTS AND MAIN RESULTS

Frequency of use of red blood cell conservation techniques was determined among institutions. Correlation was determined between use of each technique and transfusion of allogeneic red blood cells and between use of each technique and median institutional blood loss. Significant variability (p < 0.01) was detected in institutional transfusion practice with respect to the use of predonated autologous whole blood, normovolemic hemodilution, red cell salvage, and reinfusion of shed mediastinal blood. The frequency of institutional use of these techniques was not associated with allogeneic transfusion (r2 < 0.15) or blood loss (r2 < 0.10) in the low-risk population of patients examined.

CONCLUSIONS

Institutions vary significantly in perioperative blood conservation practices for CABG surgery. Further study to determine the appropriate use of these techniques is warranted.

Blood loss from coronary angiography increases transfusion requirements for coronary artery bypass graft surgery

OBJECTIVE

To determine the blood loss associated with coronary angiography and its impact on hemoglobin and transfusion requirements for subsequent coronary artery bypass graft (CABG) surgery.

DESIGN

Retrospective chart review.

SETTING

Tertiary-care, academic medical center.

PARTICIPANTS

A total of 506 adult patients undergoing coronary angiography and CABG surgery.

INTERVENTIONS

None (observational study).

MEASUREMENTS AND MAIN RESULTS

Coronary angiography was associated with a reduction in hemoglobin of 1.8 g/dL. This reduction in hemoglobin was a significant predictor of allogeneic red blood cell transfusion.

CONCLUSION

Coronary angiography contributes to a 1.8 g/dL reduction in hemoglobin concentration before CABG surgery and was associated with increased transfusion of allogeneic blood products. Measures aimed at maintaining red cell volume during coronary angiography, increasing erythropoiesis, or delaying surgery beyond 2 weeks may result in a decrease in transfusion requirements for patients undergoing CABG surgery.

Gender is an essential determinant of blood transfusion in patients undergoing coronary artery bypass graft procedure

STUDY OBJECTIVE

To determine factors that account for gender difference in the need for blood transfusion in coronary artery bypass graft (CABG) patients.

DESIGN

Retrospective study of consecutive patients.

SETTING

Anesthesiology department of a teaching hospital.

PATIENTS

253 CABG patients (163 males and 90 females).

INTERVENTIONS

Packed red blood cells (PRBCs), platelets, and fresh frozen plasma (FFP) were transfused depending on the need of each patient.

MEASUREMENTS AND MAIN RESULTS

For each patient, we recorded the gender, age, weight, height, body surface area (BSA), and duration of surgery. Hematocrit (Hct) levels prior to surgery, end of surgery, and at discharge from the hospital were recorded. PRBC administration and use of FFP and platelets were noted. Differences between the data for female and male patients were evaluated using Student's t-test, Chi-square test, and regression analysis. Approximately 60% female and only 20% male patients received PRBCs intraoperatively, whereas 78% females and only 43% males received PRBCs during their entire hospital stay. On average, females received 1.20 units of PRBCs intraoperatively and 2.38 units during the entire hospital stay, while the males received 0.31 units and 1.36 units for similar periods. Gender differences in PRBC transfusion persisted even when females and males were compared within the same subgroups for age, weight, duration of surgery, and preoperative Hct. PRBC units given intraoperatively had a significant correlation with age and preoperative Hct in females, but they had a significant correlation with age, preoperative Hct, and duration of surgery in males. PRBCs given during the entire hospital stay, however, had significant correlation with age, preoperative Hct, and duration of surgery in both females and males. Multiple logistic regression analysis showed that the probability of a patient receiving or not receiving PRBC transfusion is significantly influenced by age, preoperative PRBC mass, duration of surgery, and gender.

CONCLUSION

Gender is an independent essential determinant of blood transfusion in CABG patients, and it may interact with age, weight, preoperative Hct, duration of surgery, and other factors in determining the probability of transfusion.

Size makes a difference: use of a low-prime cardiopulmonary bypass circuit and autologous priming in small adults

Low hematocrit (Hct < 20) during cardiopulmonary bypass (CPB) is associated with higher mortality and other adverse outcomes. More frequently, low Hct is encountered in patients with small body size and women patients. This prompted us to take an aggressive approach in our care of these patients, involving a strategy for predicting patients at risk of low Hct, with the aid of an electronic worksheet that accurately predicts CPB Hct, and two prevention strategies: use of a low-prime CPB circuit (LP) for all adult patients with a body surface area (BSA) < 1.7 m(2) and use of autologous circuit priming (AP), in addition to the low-circuit volume in some patients. The two cohorts of patients in whom these techniques were employed were compared to a group matched for body size where our standard adult circuit (STD) was used. There were 233 patients in the standard group, 139 in the LP group, and 68 in the LP/AP group. The CPB circuit prime volume was 1,710 ml for the STD group and 1,110 ml for the LP group. Use of autologous priming techniques further reduced the prime volume by 545 +/- 139 ml. The incidence of low Hct (<20%) during CPB was thus reduced from 70% to 15% (p = 0.001) when using both techniques together without increasing red blood cell (RBC) transfusions. These changes in perfusion management resulted in a reduction in the incidence of renal complications (STD = 9.4%, LP = 6.5% (ns) and LP/AP = 0%,