Blood conservation during myocardial revascularization

Increasing surgeon experience and cumulative institutional experience drive decreasing hospital mortality after reoperative cardiac surgery

OBJECTIVE

The study objective was to identify the effects of surgeon experience and age, in the context of cumulative institutional experience, on risk-adjusted hospital mortality after cardiac reoperations.

METHODS

From 1951 to 2020, 36 surgeons performed 160,338 cardiac operations, including 32,871 reoperations. Hospital death was modeled using a novel tree-bagged, generalized varying-coefficient method with 6 variables reflecting cumulative surgeon and institutional experience up to each cardiac operation: (1) number of total and (2) reoperative cardiac operations performed by a surgeon, (3) cumulative institutional number of total and (4) reoperative cardiac operations, (5) year of surgery, and (6) surgeon age at each operation. These were adjusted for 46 patient characteristics and surgical components.

RESULTS

There were 1470 hospital deaths after cardiac reoperations (4.5%). At the institutional level, hospital death decreased exponentially and became less variable, leveling at 1.2% after approximately 14,000 cardiac reoperations. For all surgeons as a group, hospital death decreased rapidly over the first 750 reoperations and then gradually decreased with increasing experience to less than 1% after approximately 4000 reoperations. Surgeon age up to 75 years was associated with ever-decreasing hospital death.

CONCLUSIONS

Surgeon age and experience have been implicated in adverse surgical outcomes, particularly after complex cardiac operations, with young surgeons being novices and older surgeons having declining ability. However, at Cleveland Clinic, outcomes of cardiac reoperations improved with increasing primary surgeon experience, without any suggestion to mid-70s of an age cutoff. Patients were protected by the cumulative background of institutional experience that created a culture of safety and teamwork that mitigated adverse events after cardiac surgery.

Primary isolated CABG restrictive blood transfusion protocol reduces transfusions and length of stay

BACKGROUND

Cardiac surgery accounts for 10-15% of blood transfusions in the US, despite benefits and calls of limiting its use. We sought to evaluate the impact of a restrictive transfusion protocol on blood use and clinical outcomes in patients undergoing isolated primary coronary artery bypass grafting (CABG).

METHODS

Blood conservation measures, instituted in 2012, include preoperative optimization, intraoperative anesthesia, and pump fluid restriction with retrograde autologous priming and vacuum-assisted drainage, use of aminocaproic acid and cell saver, intra- and postoperative permissive anemia, and administration of iron and low-dose vasopressors if needed. Medical records of patients who underwent isolated primary CABG from 2009 to 2012 (group A; n = 375) and 2013 to 2016 (group B; n = 322) were compared.

RESULTS

CABG with grafting to three or four coronary arteries was performed in 262 (70%) and 222 (69%) patients and bilateral internal thoracic artery grafting in 202 (54%) and 196 (61%) patients in groups A and B, respectively. Mean preoperative and intraoperative hematocrit was 40.3% and 40.7%, 28.9% and 29.4% in groups A and B, respectively. Total blood transfusion was 24% and 6.5%, intraoperative transfusion 11% and 1.2%, and postoperative transfusion 20% and 5.6% (P < .0001 for all) in groups A and B, respectively. Median postoperative length of stay was 5.0 days in group A and 4.5 days in group B (P = .02), with no significant differences in mortality or morbidity.

CONCLUSIONS

A restrictive transfusion protocol reduced blood transfusions and postoperative length of stay without adversely affecting outcomes following isolated primary CABG.

Correlates of blood volume, red cell mass and plasma volume in coronary bypass patients

Prebypass blood volume (BV), red cell volume (RBC) and plasma volume (PV) may affect haematocrit during and after cardiopulmonary bypass (CPB), volume shift in and out of the oxygenator during CPB and the need for blood transfusion. We have calculated BV, RBC, and PV in 1076 patients having coronary artery bypass (CABG). Multiple regression analysis was performed to determine the preoperative factors which correlated with BV, RBC and PV. BV was found to correlate significantly with body surface area (BSA), sex, ejection fraction and emergency operation. RBC correlated significantly with sex, smoking, weight, emergency operation and obesity (body mass index). Significant correlations were found between PV and BSA, ejection fraction, emergency operation and sex. Body size (BSA and weight) is a major determinant of BV, RBC and PV in coronary artery surgery patients. Female patients have significantly diminished BV, RBC and PV, the decrease is greatest for RBC. Equal increases in BV and PV are associated with decreased ejection fraction. Emergency operation is correlated with increases in BV, RBC and PV. RBC is increased in smokers and the obese (BMI).

The effect of autologous blood salvage techniques upon bank blood usage and the cost of routine coronary revascularization

Preservation of autologous blood during cardiac surgery may reduce the need for homologous blood transfusions. We reviewed our experience for patients undergoing primary coronary revascularization to determine the effect of the use of the Haemonetics Cell-Saver upon blood bank resources and upon the cost of operation.

The quantity of homologous blood required by two groups of patients was compared. One group of 46 patients had operation prior to use of the Cell- Saver ; the other group of 31 patients was entered into Cell-Saver protocols. The mean number of homologous blood units transfused per patient fell strikingly (p < 0.0001) from 4.2 before to 0.5 after introduction of the Cell- Saver. Of the 31 patients in the Cell-Saver protocol, 71 % required no homologous blood while they received 2.5 units of autologous blood processed by the Cell-Saver. Related to this, the mean number of units prepared by typing and compatibility testing in anticipation of surgery fell from 10 units to five. The projected cost to the patient fell 23%. There were no adverse effects from the use of the Cell-Saver.

We conclude that the use of the Cell-Saver is justified not only to reduce the potential risks of homologous blood transfusion, but also to reduce the strain upon blood bank resources and the patient cost of primary coronary revascularization.

Human albumin in extracorporeal prime: effect on platelet function and bleeding

Purpose:

Synthetic starches have been positioned as an equivalent substitute for human albumin in extracorporeal prime, with both providing osmotic and oncotic pressure. Another effect of albumin is its ability to coat the synthetic surfaces of an extracorporeal circuit with a biopassivating protein monolayer. Whether this protein biopassivation has any benefit to the patient, assessed by platelet count, platelet function and 24-hour bleeding rate, is considered.

Methods:

Patients presenting for coronary artery bypass at a Canadian tertiary care hospital were randomized into two groups until a final study size of 20 patients was obtained. The Study Group received 2.5 g of human albumin in the extracorporeal prime and the Control Group remained protein free. Both groups included Voluven 6% as a synthetic starch. Blood samples were obtained at three intervals; Pre-bypass, During bypass (30 minutes after initiation of bypass), and Post-bypass. These samples were assayed for platelet function, platelet count and hemoglobin. Chest tube drainage over a 24-hour period was monitored.

Results:

Platelet count was significantly higher in the During sample in the Study Group (196 ± 56.5 x 109/ml versus 160 ± 18.5 x 109/ml, p<0.05), however, this difference was no longer significant with the Post-bypass sample (135 ±36.0 x 109/mL versus 127 ±19 x 109/mL). Platelet function assays (PFA) showed no significant differences. Chest tube drainage after 24 hours was significantly lower in the Study Group (586 ± 131.8 ml/24 h versus 741 ± 272.5 ml/24 h, p<0.05).

Conclusions:

Human albumin can passivate the synthetic surfaces of the extracorporeal circuit, which is supported by observations of preserved platelet count and reduced chest tube drainage. Although some statistically significant benefits were observed, the practical benefits of passivating an extracorporeal circuit with human albumin may be minimal.

Does transfusion of residual cardiopulmonary bypass circuit blood increase postoperative bleeding? A prospective randomized study in patients undergoing on pump cardiopulmonary bypass

OBJECTIVE

Homologous blood transfusion after open heart surgery puts a tremendous load on the blood banks. This prospective randomized study evaluates the efficacy of infusing back residual cardiopulmonary bypass (CPB) circuit i.e., pump blood as a means to reduce homologous transfusion after coronary artery bypass surgery (CABG) and whether its use increases postoperative drainage.

MATERIALS AND METHODS

Sixty-seven consecutive patients who underwent elective CABGs under CPB were randomized into 2 groups: (1) cases where residual pump blood was used and (2) controls where residual pump blood was not used. Patients were monitored for hourly drainage on the day of surgery and the 1(st) postoperative day and the requirements of homologous blood and its products. Data were matched regarding change in Hemoglobin, Packed Cell Volume and coagulation parameters till 1st postoperative day. All cases were followed up for three years.

RESULTS

There was a marginal reduction in bleeding pattern in the early postoperative period in the cases compared to controls. The requirement of homologous blood and its products were also reduced in the cases.

CONCLUSIONS

The use of CPB circuit blood is safe in the immediate postoperative period. The requirement of homologous blood transfusion can come down if strict transfusion criteria are maintained.

Bloodless and non-inotropic cardiac surgery under closed-circuit anesthesia

BACKGROUND

The safety of homologous blood transfusion has become a major concern for patients and physicians. Current transfusion practice is highly variable and may be associated with inappropriate blood use. Inotropic agents have been almost routinely administered perioperatively to patients undergoing cardiac surgery to overcome low cardiac output due to cardiopulmonary bypass (CPB) and cardioplegia-induced cardiac ischemic arrest. In this study, we evaluated the feasibility of bloodless and non-inotropic open-heart surgery.

METHODS

Perioperative clinical data were retrospectively collected from two groups of patients undergoing open-heart surgery by one surgeon in the same season. Twenty consecutive patients underwent a bloodless approach and received isoflurane-based closed-circuit general anesthesia and 20 consecutive patients (comparison group) underwent fentanyl-based anesthesia. A cell-saver was used for all patients to collect the CPB circuit blood for retransfusion. In the comparison group, conventional criteria were applied for blood transfusion and inotropic support and the goal was to keep hemoglobin > 10 g/dL and cardiac index > 2.2 L/min/m(2). In the bloodless group, new criteria for blood transfusion and inotropic support were used and included (1) low cardiac output syndrome, (2) impaired hemodynamic status and mixed venous oxygen saturation, (3) inadequate urine output, (4) metabolic acidosis, (5) ischemic signs on electrocardiography, and (6) patient's autonomy after being informed of and discussing the benefits and risks of blood transfusion.

RESULTS

In both groups, there was no in-hospital mortality and all patients were discharged in a stable condition. Eighteen of 20 (90%) patients did not receive blood transfusion, while inotropic support was not provided in 17 of 20 (85%) patients in the bloodless group; in contrast, blood transfusion and inotropic support were required for all patients in the comparison group (both: p<0.01). All patients in the bloodless group, except one with severe chronic obstructive pulmonary disease (1-second forced expiratory volume of 0.9 L), accomplished earlier extubation (mean+/-standard deviation, 1.2+/-1.1 hours) and shorter intensive care unit stay (3.1+/-2.1 days), as compared with patients in the comparison group (19.5+/-2.5 hours and 5.1+/-1.7 days, respectively; both: p<0.01). Systemic vascular resistance was significantly lower in the bloodless group.

CONCLUSION

In conclusion, bloodless and non-inotropic cardiac surgery is feasible with the aid of a cell-saver and closed-circuit anesthesia in combination with new practice guidelines.

Should the cardiotomy suction blood be cell-saver processed before retransfusion? A clinico-pathologic mystery

The use of cardiotomy suction (CS) in cardiopulmonary bypass (CPB) surgery is associated with a pronounced systemic inflammatory response and a resulting coagulopathy as well as exacerbating the microembolic load. However, CS is yet been employed to preserve autologous blood during on-pump surgery. Though processing CS blood with a cell saving device is considered paramount in significantly reducing the inflammatory effects, yet this might also have potential harmful effects on the outcome of the patient. Here we discuss the results of the different prospective and randomized studies to address these issue if the cell saver technique in processing CS blood before retransfusion is to establish its identity and role in the CPB surgery.

Identifying Patients at Risk of Intraoperative and Postoperative Transfusion in Isolated CABG: Toward Selective Conservation Strategies

BACKGROUND

Allogeneic blood product use during cardiac operation is often reported to exceed 40% despite published guidelines and costly blood conservation strategies. We developed a predictive model, based on eight preoperative risk factors, of allogeneic blood product transfusion rates in patients undergoing a cardiac procedure.

METHODS

All 3,046 consecutive, isolated coronary artery bypass graft (CABG) procedures at a university hospital from 1995 to 1998 were included. A logistic regression model was created to identify independent predictors of allogeneic blood product transfusion. This model was validated using a prospective patient sample.

RESULTS

Overall use of allogeneic blood products was 23% with a crude operative mortality of 2.1%. In isolated, elective, first-time CABG cases, 16.9% received allogeneic blood products. Independent predictors of blood product usage in CABG patients were preoperative hemoglobin 12.0 or less, emergent operation, renal failure, female sex, age 70 years or older, left ventricular ejection fraction 0.40 or less, redo procedure, and low body surface area. Prospective validation of this model on 2,117 consecutive isolated CABG patients demonstrated an observed-to-expected allogeneic blood product transfusion rate ratio of 1.06.

CONCLUSIONS

This internally validated logistic regression risk model is a sensitive and specific predictor of allogeneic blood product use in patients undergoing isolated CABG. Utilization of this model allows for preoperative risk stratification and may allow for more rational resource allocation of costly blood conservation strategies and blood bank resources.

Vacuum-assisted venous return reduces blood usage

OBJECTIVE

To determine whether vacuum-assisted venous return has clinical advantages over conventional gravity drainage apart from allowing the use of smaller cannulas and shorter tubing.

METHODS

A total of 150 valve operations were performed at our institution between February and July 1999 using vacuum-assisted venous return with small venous cannulas connected to short tubing. These were compared with (1) 83 valve operations performed between April 1997 and January 1998 using the initial version of vacuum-assisted venous return, and (2) 124 valve operations performed between January and April of 1997 using conventional gravity drainage. Priming volume, hematocrit value, red blood cell usage, and total blood product usage were compared multivariably. These comparisons were covariate and propensity adjusted for dissimilarities between the groups and confirmed by propensity-matched pairs analysis.

RESULTS

Priming volume was 1.4 +/- 0.4 L for small-cannula vacuum-assisted venous return, 1.7 +/- 0.4 L for initial vacuum-assisted venous return, and 2.0 +/- 0.4 L for gravity drainage (P <.0001). Smaller priming resulted in higher hematocrit values both at the beginning of cardiopulmonary bypass (27% +/- 5% compared with 26% +/- 4% and 25% +/- 4%, respectively, P <.0001) and at the end (30% +/- 4% compared with 28% +/- 4% and 27% +/- 4%, respectively, P <.0001). Red cell transfusions were used in 17% of the patients having small-cannula vacuum-assisted venous return, 27% of the initial patients having vacuum-assisted venous return, and 37% of the patients having gravity drainage (P =.001); total blood product usage was 19%, 27%, and 39%, respectively (P =.002). Although ministernotomy also was associated with reduced blood product usage (P <.004), propensity matching on type of sternotomy confirmed the association of vacuum-assisted venous return with lowered blood product usage.

CONCLUSIONS

Vacuum-assisted venous return results in (1) higher hematocrit values during cardiopulmonary bypass and (2) decreased red cell and total blood product usage.

Pharmacotherapeutic considerations in anesthesia

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

The effect of postoperative normovolaemic anaemia and autotransfusion on blood saving after internal mammary artery bypass surgery

The efficacy of two blood conservation techniques in decreasing and in preventing the use of homologous blood products was retrospectively studied in 150 patients undergoing internal mammary artery bypass surgery. Patients were matched according to prebypass blood haemoglobin (Hb) content and body surface area and were allocated to one of three groups: in the patients of group 1 (n = 50), normovolaemic anaemia (NA) was accepted postoperatively (haematocrit [Hct] was accepted to a minimum level of 25%); the patients of group 2 (n = 50) were treated with postoperative autotransfusion (AT) of mediastinal shed blood and acceptance of NA. Group 3 (n = 50) contained control patients, not treated with NA or with AT (Hct was accepted to a minimum level of 30%). Patients of group 1 required 3.0 +/- 0.3 units of homologous blood products, but the patients of groups 2 and 3 received significantly more (p less than 0.01) units: 3.9 +/- 0.2 and 4.5 +/- 0.3 units. No donor blood products were needed in 36%, 9% and 5% of the patients in groups 1, 2 and 3 respectively. The net postoperative blood loss was similar in the groups: 1229 +/- 92 ml in group 1, 1098 +/- 74 ml in group 2 and 1243 +/- 72 ml in group 3. However, total blood loss (1982 +/- 135 ml), including the retransfused part (954 +/- 89 ml), was significantly larger (p less than 0.01) in group 2, than in groups 1 and 3.(ABSTRACT TRUNCATED AT 250 WORDS)

Transfusion policies in coronary artery bypass--a nationwide survey in Finland

BACKGROUND

Since the discovery of HIV, minimizing the use of donor blood has become increasingly important in surgical activity. In Finland, however, the use of homologous red blood has grown considerably during the past years. Therefore, we found it necessary to conduct a nationwide survey of transfusion practices in elective surgery. This report deals with transfusions in coronary artery bypass (CABG) operations in all Finish cardiac centres.

METHODS

The study group comprised 804 primary CABG patients operated during a 2-year period. Two reviewers retrospectively examined the data concerning the use of and indications for homologous and autologous blood in the patient charts.

RESULTS

In all, 705 (88%) of patients received homologous blood. The proportions of patients receiving blood components differed between hospitals: from 53 to 99% for red cells, 2 to 22% for fresh frozen plasma and 5 to 49% for platelets. The variation was not caused by diverse patient populations: the mean number of blood component units transfused per patient differed from 1 to 6 between centres-even after adjustment for confounding variables. Multiple blood conservation methods were used in one centre. Nevertheless, homologous blood was administered to 88% of their patients.

CONCLUSIONS

A considerable proportion of CABG patients are transfused with homologous blood in Finland compared to other countries. In addition, the transfusion practices proved highly variable between hospitals and were determined largely by local opinions. This study reveals a clear demand for prospective studies and constructive discussion among anaesthesiologists to establish uniform guidelines for blood use in cardiac surgery.

Does heparin coating improve biocompatibility? A study on complement, blood cells and postoperative morbidity during cardiac surgery

To evaluate whether the effect of heparin coating the extracorporeal circuit resulted in differences in patient outcome and haemostatic alteration, 24 patients undergoing elective, isolated coronary artery bypass were randomized prospectively to cardiopulmonary bypass (CPB) with heparin-coated circuits (group H, n = 12) or uncoated circuits (group C, n = 12). The technique of CPB, heparinization and its reversal were the same in both groups. We studied complement status (C3d, C3, C3d/C3, C4 and C-function), white blood cell counts with differentiation and the postoperative morbidity. The results confirmed that CPB activates complement and increases neutrophils in both the H and C groups. A significantly lower level of leucocytosis was seen in group H compared to the C group (p < 0.05). The complement function via the classical pathway (C-function), expressed as a percentage of the function of a reference serum pool (the values of normal sera were 75-125%), was significantly reduced in both heparin-coated and uncoated circuits (p < 0.05). There was no significant intergroup difference regarding C3, C3d/C3, C4 and C-function during the study period. A lower frequency of postoperative morbidity was present in the H group. We conclude that heparin-coated surfaces elicit less leucocytosis and decrease postoperative morbidity in patients undergoing cardiac surgery but do not cause a significant difference regarding activation of the complement system as reported by many other investigators.

Current red blood cell transfusion practices

The appropriate use of blood transfusions remains variable among health-care institutions and patient populations. Transfusion practices are discussed in this article in relation to medical practice guidelines and utilization review. Specific transfusion practices in the settings of intensive care, orthopedic surgery, and open heart surgery are reviewed. A new, promising approach to improving transfusion outcomes is the use of transfusion algorithms. Transfusion algorithms may prove especially useful if they incorporate point-of-care testing that is both physiologic and patient-specific for transfusion decisions. Transfusion algorithms are discussed and data presented for cardiac surgical adults.

Autotransfusion after coronary artery bypass grafting halves the number of patients needing blood transfusion

BACKGROUND

Several randomized studies about autotransfusion of shed mediastinal blood in patients undergoing coronary artery bypass grafting have resulted in divergent findings concerning reduction of the need for homologous blood transfusions. Most of these studies used less strict criteria for homologous blood transfusion than applied in daily clinical practice.

METHODS

A prospective, randomized, controlled study involving 120 patients having elective, uncomplicated coronary artery bypass grafting was performed. The autotransfusion group received transfusion of shed mediastinal blood for 18 hours. Criteria for homologous blood transfusion were hemoglobin concentration less than 5.0 mmol/L in the intensive care unit and less than 5.5 mmol/L during the rest of the hospital stay.

RESULTS

Twenty-eight percent of patients in the autotransfusion group received homologous blood transfusion versus 55% in the control group (p = 0.007). Ninety-five percent of the shed mediastinal blood was transfused. In the autotransfusion group, a total of 26 units of homologous blood was used versus 78 units in the control group (p < 0.001).

CONCLUSIONS

Autotransfusion of shed mediastinal blood in patients undergoing elective, uncomplicated coronary artery bypass grafting halves the number of patients needing homologous blood and reduces the amount of homologous blood given.

Alternatives to allogeneic blood use in surgery: acute normovolemic hemodilution and preoperative autologous donation

Acute normovolemic hemodilution (ANH) is a common blood conservation strategy in elective surgical procedures. Moderate ANH is safe in patients > 60 years of age; ANH is not recommended for patients who have coronary artery disease, significant anemia, renal disease, severe hepatic disease, pulmonary emphysema, or obstructive lung disease. Preservation of oxygen delivery during ANH depends on the maintenance of normovolemia to avoid decompensation and falling cardiac output. Preoperative autologous donation (PAD) as a blood conservation strategy has the advantage of protecting the patient from risks associated with allogenic transfusion, but it is expensive and time consuming. No protocols have established a preference for either ANH or PAD; an early study suggested that ANH is less expensive and more effectively preserves blood components, but other researchers warn that the methodology for ANH remains unresolved.

Establishing practice guidelines for surgical blood management

Medical practice guidelines have been promoted as a way to improve the cost-effectiveness of medical care. Algorithms for the transfusion of red blood cells, plasma, and platelets may be especially useful in the surgical setting if they incorporate point-of-care information that is both physiologic and patient-specific for transfusion decision making. Therefore, the goals of guidelines for surgical blood management should be twofold. They should (1) acknowledge patient-specific variability while addressing physician- and institution-dependent variables; and (2) improve blood component management by developing more physiologic clinical indicators of the need for allogeneic red blood cell transfusion.

Autotransfusion after open heart surgery: quality of shed mediastinal blood compared to banked blood

The need to conserve a patient's own blood and avoid homologous transfusion is now well recognized. Therefore, techniques designed to reduce requirements for homologous blood transfusions have been developed. One of the methods is autotransfusion of shed mediastinal blood after open-heart surgery. The objectives of the present study were to investigate osmotic fragility and oxygen transport capacity of shed mediastinal blood compared to patient blood and stored packed red blood cells (SAGM). Shed mediastinal blood from ten consecutive patients undergoing elective cardiac surgery (coronary bypass grafting) was studied and compared to patient blood, 10 units of 3 weeks old and 10 units of 5 weeks old stored packed red blood cells (SAGM). Oxygen transport capacity was investigated by calculation of p50 for oxygen by use of the oxygen status algorithm (OSA 2.0) programme and measurement of 2,3-diphosphoglycerate (2,3-DPG) concentrations. The osmotic fragility was determined using increasing concentrations of saline. 2,3-DPG concentrations in shed mediastinal blood (5.3 mikromol/ml erythrocyte) were within the range measured in patient blood, but significantly higher than SAGM blood (P < 0.001). P50 for oxygen (3.5 kPa) in shed mediastinal blood was not significantly different compared to patient blood, but significantly higher (P < 0.01) compared with stored SAGM blood. The osmotic fragility in shed mediastinal blood was not significantly different compared to patient blood, but significantly lower (P < 0.001) than the osmotic fragility in stored SAGM blood. This suggests that red cells saved from shed mediastinal blood have better oxygen transport capacity and may have longer survival compared to stored blood.

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

BACKGROUND

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

METHODS AND RESULTS

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

CONCLUSIONS

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

Autotransfusion after open heart surgery: the oxygen delivery capacity of shed mediastinal blood is maintained

Autotransfusion of mediastinal shed blood after open heart surgery has become a common and accepted procedure in reducing the need for homologous transfusion during the last 15 years. The objectives of the present study were to investigate the oxygen delivery capacity of autotransfused shed mediastinal blood, compared to patient-blood, during cardiopulmonary bypass and in the postoperative period. Ten consecutive patients undergoing elective cardiac surgery were studied. Mediastinal shed blood was collected in the cardiotomy reservoir and retransfused during the first 18 postoperative hours. The oxygen delivery capacity of the blood to the tissues was calculated by use of the oxygen status algorithm (OSA 2.0) programme and measurement of the 2,3-diphosphoglycerate (2,3-DPG) concentration. Autotransfusion volume ranged from 450-1530 ml per patient (median 824 ml). Shed blood had a mean haemoglobin level of 8.8 g/dl and 7.4 g/dl at 1 h and 6 h of autotransfusion, respectively. There were no significant changes of 2,3-DPG concentration in the patient-blood during cardiopulmonary bypass or after autotransfusion compared to preoperative values. P50 for oxygen (3.6 and 3.6 kPa) and 2,3-DPG concentrations (5.3 and 5.1 mikromol/ml erythrocyte) in shed mediastinal blood (1h and 6h postoperatively) were not significantly different compared to patient-blood. The results demonstrate that the oxygen delivery capacity of shed mediastinal blood is maintained and that the oxygen affinity of patient-blood is not influenced by autotransfusion.

On the need for improved transfusion indicators in cardiac surgery

Guidelines for transfusion practice have had limited impact in altering physician transfusion behavior in patients undergoing cardiac operations. This may be due to a lack of consensus on the relative risks and benefits of blood in these patients who are anemic, limited access to timely data that are necessary on which to base transfusion decisions, the recognition that empiric hemoglobin/hematocrit thresholds are limited clinical indicators of the need for blood, or a combination of these. We present an overview of current transfusion and blood conservation practices in this setting, along with possible approaches to guide the decision-making process by coupling the use of transfusion algorithms with point of care testing to use more physiologic indicators of the need for blood transfusion.

Prospective evaluation of minimal blood use for ascending aorta and aortic arch operations

The feasibility, safety, and impact on postoperative hospital stay of performing ascending aorta and aortic arch operations without homologous blood transfusions have not been evaluated. Sixty consecutive patients, 38 (63%) of whom also had aortic valve replacements and 17 (28%) of whom also had coronary artery bypass grafting, were evaluated for participation in blood conservation measures. Of the 45 who were able to use blood conservation techniques, 87% (39/45) required no intraoperative and 69% (31/45) required no in-hospital homologous blood transfusions. The 30-day survival rate was 98.3% (59/60), and no patient sustained a new stroke, neurologic cognitive deficit, or infection. Multivariate analysis of the 60 patients showed that the predictors of in-hospital homologous transfusion were (p < 0.05) age, cardiopulmonary bypass time, and postoperative chest tube drainage. Preoperative autologous blood donation was associated with a significantly lower risk of homologous transfusion (p = 0.0006). Indeed, patients participating in blood conservation techniques had a significantly (p < 0.05) lower incidence of homologous transfusions, required less intraoperative shed blood washing, were extubated earlier, gained less weight, had shorter hospital stays, and were discharged in a better dyspnea functional class. Most major elective cardiovascular operations on the ascending aorta and aortic arch can be safely performed without homologous transfusions.

The effect of multiple blood conservation techniques on donor blood exposure in adult coronary and valve surgery performed with a membrane oxygenator: a multivariate analysis on 1310 patients

The object of the study was to retrospectively evaluate protective and risk factors for receiving donor blood products and red cell transfusions after coronary and valve surgery performed with a hollow-fiber oxygenator and with multiple blood-saving techniques. During the period of January 1991 to June 1993, 1310 patients underwent primary coronary and valve surgery using a hollow-fiber oxygenator at our institution; the mean age of this population was 61 +/- 10 years; 977 patients were men (74.6%). Of these patients, 73.5% (963/1310) underwent coronary, 21.5% (281/1310) valve, and 5% (66/1310) combined surgery. Two hundred seventy-six (21.1%) needed donor blood product transfusions, while 153 (11.7%) patients underwent red cell transfusions. Significant risk factors for homologous blood product exposure after multivariate logistic regression analysis were, in order of importance: (1) postoperative blood loss (O.R. = 1.0009 per mL, p = 0.0000); (2) cardiopulmonary bypass (CPB) time (O.R. = 1.008 per min, p = 0.0001); (3) age at intervention (O.R. = 1.031 per calendar year, p = 0.0026); and (4) reoperation for bleeding (O.R. = 1.71, p = 0.0078). Protective factors were: (1) male gender (O.R. = 0.56, p = 0.0000); (2) preoperative withdrawal of autologous blood (O.R. = 0.66, p = 0.0018); and (3) a preoperative hematocrit greater than 34% (O.R. = 0.76, p = 0.0005).(ABSTRACT TRUNCATED AT 250 WORDS)

Hemostatic efficacy of dipyridamole, tranexamic acid, and aprotinin in coronary bypass grafting

Sixty patients (four groups of 15 patients) were entered in a randomized, controlled study to compare the efficacy of prophylactic treatment with dipyridamole, tranexamic acid, and aprotinin to reduce bleeding after elective coronary artery bypass grafting. Only patients with a preoperative platelet count of less than 246 x 10(9)/L were selected because a previous study showed that these individuals are at risk for increased postoperative bleeding. Compared to control subjects, postoperative blood loss 6 hours after operation was significantly reduced by tranexamic acid (674 +/- 411 versus 352 +/- 150 mL; p < 0.05) and by aprotinin (270 +/- 174 mL; p < 0.01). Dipyridamole did not reduce postoperative blood loss and was associated with complications in 3 patients. We conclude that hemostasis after cardiac operations can be improved with tranexamic acid and aprotinin. Dipyridamole appeared to be ineffective.

Erythropoietin in cardiac surgery

Erythropoietin is the primary growth factor for red blood cells. A glycoprotein hormone synthesized by the kidneys, erythropoietin serves to increase red blood cell production in response to tissue hypoxia. It exerts its effect by increasing the numbers of erythroid progenitor cells in the bone marrow, and by increasing the rate at which their development is accomplished. With the introduction of recombinant erythropoietin in 1987, an important pharmacological agent became available for the manipulation of erythropoiesis. While used primarily for the treatment of the anemia of renal failure, recombinant erythropoietin has also shown usefulness in treating other types of anemias in which the endogenous erythropoietin response is insufficient. Perioperative use of the drug grew as a natural extension of this, and erythropoietin has been applied to correct preoperative anemia, augment autologous blood donation, and improve postoperative red cell recovery. Analysis of these perioperative clinical studies reveals success in these areas, but it also reveals that closer attention to the physiology of the natural response, and to the pharmacology of the recombinant product, might significantly improve results. Such an improvement in efficacy is both desirable and necessary when use of the drug is viewed in the setting of today's changing health care environment. By optimizing dosing schedules and targeting the drug to those most at risk for red cell transfusion, recombinant erythropoietin will likely become an important tool in efforts to achieve the elusive goal of bloodless cardiac surgery.

The impact of intraoperative autotransfusion on cardiac surgery. A prospective randomized double-blind study

The effect of intraoperative autotransfusion during coronary artery bypass grafting was studied in a randomized double-blind trial involving 38 patients. Nineteen patients had the collected RBCs washed and autotransfused (autotransfusion group), while the remaining patients had their washed cells discarded (control group). Postoperative hemoglobin and hematocrit values were similar. Exposure to banked blood was markedly decreased in the autotransfusion group compared with the control group. In addition, the mean volume of banked packed RBCs transfused per patient was significantly less in the autotransfusion group compared with the control group. Platelet utilization also was markedly decreased in the autotransfusion group. Cryoprecipitate and fresh frozen plasma utilization also was less in the autotransfusion group than in the control group, but this did not reach statistical significance. We conclude that the intraoperative use of autotransfusion decreases the volume of homologous blood products transfused, which results in reduced exposure of the patients to banked blood products.

Prospective, randomized trial of autotransfusion after routine cardiac operations

To study the effectiveness of autotransfusion of shed mediastinal blood in decreasing the need for homologous blood transfusion in the routine cardiac surgical patient, we prospectively randomized 35 consecutive patients into two groups. The experimental group (n = 18) received autotransfusion for 12 hours after completion of the operative procedure. The control group (n = 17) was treated with standard chest drainage and fluid replacement. Both groups received homologous blood transfusion when the hemoglobin level fell to less than 8.0 g/dL. Student's t test, chi 2 analysis, and multivariate logistic regression analysis were used where appropriate. Packed red blood cells were required postoperatively in 6 of the 17 control and 6 of the 18 autotransfusion patients (p = not significant). Postoperative colloid fluid replacement (excluding autotransfusion fluid) in the autotransfusion group (333 +/- 78 mL; 95% confidence bounds, 168 to 498 mL) was less than in the control group (615 +/- 114 mL; 95% confidence bounds, 372 to 857 mL; p = 0.048). Total homologous blood product exposure tended to be higher in autotransfusion patients (83%) than in control patients (47%) (p = 0.057). Fibrin split products were elevated only in the serum of the autotransfusion patients (p < 0.002). No transfusion-related complications were apparent in either group. Although the sample size is small, autotransfusion of shed mediastinal blood does not appear to decrease the need for homologous blood transfusion in the routine cardiac surgical patient.

Blood conservation and autotransfusion in cardiac surgery

Blood conservation techniques of withdrawal of blood just before surgery, intraoperative blood salvage with Solcotrans (Solco Basle [UK] Ltd.), and profound hemodilution were used in 14 patients undergoing open heart surgery (group I) and compared with equally matched 14 patients who had profound hemodilution only during cardiopulmonary bypass (CPB) and acted as controls (group II). Group I patients required a mean of 255 mL of homologous blood per patient to achieve a target hemoglobin of 8 g/dL compared to group II patients who required a mean of 1,011 mL per patient (p = 0.0001). By using autologous blood there was a marked reduction in homologous blood exposure. Eight patients in group I and two patients in group II required no homologous blood. No adverse events occurred. In the process of conservation of blood in open heart surgery, we found the combination of the above techniques used in Group I patients to be safe and effective.

Intraoperative autologous blood salvage with cardiac surgery: an analysis of five years' experience in more than 3,000 patients

STUDY OBJECTIVE

To analyze intraoperative autologous salvage of shed mediastinal blood and subsequent transfusion in cardiac surgery.

DESIGN

Retrospective statistical analysis.

SETTING

University hospital.

PATIENTS

Three thousand twenty two patients undergoing cardiac surgery from 1984 to 1988.

INTERVENTIONS

A review of anesthesia and transfusion records of all patients who underwent intraoperative salvage of shed blood and autologous transfusion using the Sorenson Receptal Auto Transfusion System (ATS) with saline wash prior to reinfusion in cardiac surgery.

MEASUREMENTS AND MAIN RESULTS

The salvaged blood volume ranged from 36 to 2,795 ml, with a mean of 321 +/- 222 ml (SD). Eighteen percent of patients did not receive any homologous blood products during their hospitalization. Patients who received only salvaged autologous transfusion were younger, had higher preoperative hemoglobin and hematocrit values, had a larger body surface area, and had shorter surgeries compared with patients who received only homologous blood or both autologous and homologous blood. More blood products were given to patients who received salvaged autologous blood compared with those who did not. Patients who underwent normovolemic hemodilution prior to extracorporeal circulation with subsequent reinfusion received significantly fewer blood products. Ten preoperative and four intraoperative variables significantly influenced the salvaged volume. Previous cardiac surgery was the most significant preoperative variable, and repair of ventricular septal defect produced by myocardial ischemia was the most significant intraoperative variable.

CONCLUSION

Considering the average salvaged volume and its current autologous transfusion-related expense, autologous blood salvage is potentially an economic benefit. Perioperative blood conservation requires a considerable commitment from surgeons, anesthesiologists, perfusionists, and intensive care physicians to be effective.

Autotransfusion of unwashed mediastinal shed blood fails to decrease banked blood requirements in patients undergoing aortocoronary bypass surgery

Infusion of unwashed mediastinal shed blood (MSB) is one technique advocated for decreasing use of donor blood in cardiac surgery patients. A commercially available system was prospectively evaluated in 96 consecutive patients. The control group was comprised of 78 consecutive patients. All underwent elective aortocoronary bypass surgery. Student's t-test, chi-square analysis, multivariate analysis, and Fisher's exact test were used where appropriate. There was no decrease in the amount of banked blood required or percentage of patients who received transfusions in the MSB autotransfusion group.

Blood salvage in cardiac surgery

The aim of this study was to evaluate blood salvage provided by an intraoperative blood recovery system (IBRS) and a mediastinal drainage blood recovery system (MBRS) during and after cardiac surgery. Sixty-six patients undergoing aortocoronary bypass surgery were randomly assigned to three groups of 22 patients each. In group I, patients received only homologous blood (HB). Group II and group III patients received the blood content of the oxygenator after concentration by an IBRS at the end of the operation. In group III, patients also received their own mediastinal drainage blood, shed for 6 hours after operation, after concentration and washing in a MBRS. The patients were transfused with homologous blood if needed, in order to obtain a hematocrit of 28% at the end of operation, 30% the following day, and a hemoglobin level over 10 g/dL while on the cardiac surgery ward (8 to 10 days). The three groups were comparable with respect to age, body surface, preoperative and postoperative hematocrits, number of grafts, bypass duration, and postoperative mediastinal blood loss. The amount of HB that was transfused during the operation was significantly lower in groups II and III than in group I (P less than 0.0001). After the operation it was significantly lower in group II than in group I (P less than 0.05), and in group III versus group I. Thus, 13.6% of patients in group II and 38% of patients in group III did not require HB transfusion. No infection, renal dysfunction, or coagulation disorders were observed. It is concluded that the use of an IBRS allows a significant saving of HB. However, because it does not avoid all HB requirements, it should be associated with other techniques to avoid blood transfusion such as the MBRS or predonation.

Con: desmopressin is not of value in the treatment of post-cardiopulmonary bypass bleeding

Following two early promising reports that treatment with intravenous DDAVP was helpful in reducing postoperative hemorrhage and the amount of transfusion with homologous blood products in patients who had undergone cardiac surgery with CPB, these results were not repeated in any of the follow-up studies. At the present time, the routine prophylactic use of DDAVP in cardiac surgery cannot be recommended for patients undergoing closure of atrial septal defect, valve repair or replacement, primary CABG, or in children requiring cardiac surgery. The use of DDAVP in complicated procedures or for control of severe postoperative bleeding remains controversial. In the authors' opinion, DDAVP should not be used in cardiac surgery except in patients with a presurgical DDAVP-responsive coagulopathy.

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

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

Benefit from combining blood conservation measures in cardiac operations

Conventional blood conservation techniques have been insufficient to decrease transfusion needs in increasingly complex cardiac operations. To evaluate combinations of conservation techniques, 300 patients were divided into three equal groups. Group 1 had intraoperative autotransfusion and return of mediastinal drainage for 4 hours postoperatively. Group 2 had these measures plus intraoperative plasmapheresis. These two groups were given a transfusion for a hematocrit of less than 0.21 on cardiopulmonary bypass. Group 3 was treated with the same measures as group 2 but did not receive transfusions while on pump unless the hematocrit decreased to less than 0.15. The percentage of patients in each group given transfusions in the operating room was 34% in group 1, 28% in group 2, and 7% in group 3 (p less than 0.05). The percentage of all patients receiving transfusions during hospitalization was 68% in group 1, 36% in group 2 (p less than 0.05), and 18% in group 3 (p less than 0.05). Average total units transfused were 2.16 +/- 0.25 in group 1, 0.7 +/- 0.15 in group 2 (p less than 0.05), and 0.37 +/- 0.07 in group 3 (p less than 0.05). The perioperative morbidity rates including myocardial infarctions and strokes were similar. There were no deaths in group 3. Combining complementary conservation measures is effective in reducing homologous blood transfusions, and the need for transfusion can be safely reduced by allowing profound hemodilution during bypass.

Blood coagulation and autologous blood transfusion in cardiac surgery

STUDY OBJECTIVE

To review the basic pathophysiology of altered coagulation associated with cardiopulmonary bypass and autologous blood transfusion in cardiac surgery.

DESIGN

Review of rational use of heparin, mechanisms and treatment of coagulation disorders, and autologous blood transfusion.

SETTING

Cardiac surgery in community and academic hospitals.

PATIENTS

Adult cardiac surgical patients.

MAIN RESULTS

Heparin is most commonly used for anticoagulation during cardiopulmonary bypass. Although activated clotting time is widely used to assess heparin-induced anticoagulation, the minimum time to prevent clotting during cardiopulmonary bypass remains unclear. Activated clotting time is affected by many factors other than heparin, such as antithrombin III, blood temperature, platelet count, and age. The rational use of activated clotting time still must be defined. The frequency of abnormal bleeding after cardiopulmonary bypass is significant. Although inadequate surgical hemostasis is the most frequent cause of bleeding, altered coagulation often is present. A decreased number of functional platelets is one of the important causes of bleeding diathesis. Platelet dysfunction is induced by perioperative medication such as aspirin. Cardiopulmonary bypass decreases functional platelets by degranulation, fragmentation, and loss of fibrinogen receptors. Medications such as prostacyclin and iloprost may be useful to protect these platelets. Desmopressin increases factor VIII:C and von Willebrand's factor, leading to a decrease in bleeding time. Desmopressin may be useful to decrease blood loss in repeat cardiac operations, complex cardiac surgery, and abnormal postoperative bleeding. Patients undergoing coronary artery bypass grafting immediately after streptokinase infusion also are at risk for abnormal bleeding. Transfusion of fresh-frozen plasma and cryoprecipitate may be necessary. Autologous blood transfusion is cost-effective and the safest way to avoid or decrease homologous blood transfusion. Predonation, intraoperative salvage, and postoperative salvage are encouraged. Erythropoietin may be useful in increasing the amount of predonation red cells.

CONCLUSIONS

Coagulation disorders in cardiac surgery are caused by many factors, such as heparin, platelet dysfunction, and fibrinolysis. Rational use of blood component therapy and medications such as heparin, protamine, and desmopressin are mandatory. Autologous blood transfusion is very useful in decreasing or obviating the use of homologous blood transfusion.