Systemic blood activation during and after autotransfusion

Effects of Unprocessed and Processed Cardiopulmonary Bypass Blood Retransfused into Patients after Cardiac Surgery

Background

The aim of this prospective study was to compare the effect of autologous unprocessed to processed residual cardiopulmonary bypass blood (CPB) on patients’ laboratory and clinical parameters and outcome.

Methods

20 patients undergoing elective coronary artery bypass surgery were randomized to receive either unprocessed CPB blood (control group) or processed CPB blood employing the Continuous AutoTransfusion System (CATS; Fresenius, Bad Homburg, Germany). We have shown that this method eliminated >93% of activated mediators. Serial laboratory parameters including complement activation, coagulation factors and the stimulation of IL-6 and IL-8 were compared with clinical side effects and patients’ outcome.

Results

Compared to control patients, retransfusion of unprocessed CBP blood significantly increased heparin, free plasma hemoglobin and D-Dimers. Postoperatively, three patients in the control group and two patients in the CATS group required prolonged mechanical ventilation or developed infections associated respectively with elevated C3a (desArg) or IL-6 concentration.

Conclusions

CATS-processing of CPB blood provided a high-quality red blood cell concentrate, resulting in a reduced load of retransfused activated mediators.

The Safety and Efficacy of “Bloodless” Cardiac Surgery

Nearly 20% of blood transfusions in the United States are associated with cardiac surgery. Despite the many blood conservation techniques that are available, safe, and efficacious for patients undergoing cardiac surgery, many of these operations continue to be associated with significant amounts of blood transfusion. Although surgical bleeding after cardiopulmonary bypass is a common problem as reflected by the substantial use of blood products, it is the individual physician and institutional behavior that have been identified as reasons for transfusion and not necessarily patient comorbidity or blood loss. Transfusion rates in cardiac surgery remain high despite major advances in perioperative blood conservation, with large variations among individual centers. The adoption of available blood conservation techniques, either alone or in combination in patients undergoing cardiac surgery, could result in an estimated 75% reduction of unnecessary transfusions. The success of previously reported blood conservations programs in cardiac surgery should call for a reevaluation of allogeneic transfusion practices in patients undergoing cardiac surgery. By applying the numerous reported blood conservation strategies for the management of patients presenting for cardiac surgery, we can preserve our dwindling blood resources and help alleviate some of the direct costs of blood as well as the indirect costs of treating noninfectious and infectious complications of transfusion.

Blood Conservation Strategies in Cardiac Surgery

Perioperative bleeding in cardiac surgery is related to both surgical trauma of blood vessels and defects in the hemostatic mechanism caused, in part, by cardiopulmonary bypass. Blood transfusion therefore remains a significant risk of cardiac surgery with important health and economic consequences. Blood conservation strategies for cardiac surgery have advanced over the years and the following discussion will focus on the current practices at Toronto General Hospital.

Strategies to prevent intraoperative lung injury during cardiopulmonary bypass

During open heart surgery the influence of a series of factors such as cardiopulmonary bypass (CPB), hypothermia, operation and anaesthesia, as well as medication and transfusion can cause a diffuse trauma in the lungs. This injury leads mostly to a postoperative interstitial pulmonary oedema and abnormal gas exchange. Substantial improvements in all of the above mentioned factors may lead to a better lung function postoperatively. By avoiding CPB, reducing its time, or by minimizing the extracorporeal surface area with the use of miniaturized circuits of CPB, beneficial effects on lung function are reported. In addition, replacement of circuit surface with biocompatible surfaces like heparin-coated, and material-independent sources of blood activation, a better postoperative lung function is observed. Meticulous myocardial protection by using hypothermia and cardioplegia methods during ischemia and reperfusion remain one of the cornerstones of postoperative lung function. The partial restoration of pulmonary artery perfusion during CPB possibly contributes to prevent pulmonary ischemia and lung dysfunction. Using medication such as corticosteroids and aprotinin, which protect the lungs during CPB, and leukocyte depletion filters for operations expected to exceed 90 minutes in CPB-time appear to be protective against the toxic impact of CPB in the lungs. The newer methods of ultrafiltration used to scavenge pro-inflammatory factors seem to be protective for the lung function. In a similar way, reducing the use of cardiotomy suction device, as well as the contact-time between free blood and pericardium, it is expected that the postoperative lung function will be improved.

Perioperative blood transfusion and blood conservation in cardiac surgery: the Society of Thoracic Surgeons and The Society of Cardiovascular Anesthesiologists clinical practice guideline

BACKGROUND

A minority of patients having cardiac procedures (15% to 20%) consume more than 80% of the blood products transfused at operation. Blood must be viewed as a scarce resource that carries risks and benefits. A careful review of available evidence can provide guidelines to allocate this valuable resource and improve patient outcomes.

METHODS

We reviewed all available published evidence related to blood conservation during cardiac operations, including randomized controlled trials, published observational information, and case reports. Conventional methods identified the level of evidence available for each of the blood conservation interventions. After considering the level of evidence, recommendations were made regarding each intervention using the American Heart Association/American College of Cardiology classification scheme.

RESULTS

Review of published reports identified a high-risk profile associated with increased postoperative blood transfusion. Six variables stand out as important indicators of risk: (1) advanced age, (2) low preoperative red blood cell volume (preoperative anemia or small body size), (3) preoperative antiplatelet or antithrombotic drugs, (4) reoperative or complex procedures, (5) emergency operations, and (6) noncardiac patient comorbidities. Careful review revealed preoperative and perioperative interventions that are likely to reduce bleeding and postoperative blood transfusion. Preoperative interventions that are likely to reduce blood transfusion include identification of high-risk patients who should receive all available preoperative and perioperative blood conservation interventions and limitation of antithrombotic drugs. Perioperative blood conservation interventions include use of antifibrinolytic drugs, selective use of off-pump coronary artery bypass graft surgery, routine use of a cell-saving device, and implementation of appropriate transfusion indications. An important intervention is application of a multimodality blood conservation program that is institution based, accepted by all health care providers, and that involves well thought out transfusion algorithms to guide transfusion decisions.

CONCLUSIONS

Based on available evidence, institution-specific protocols should screen for high-risk patients, as blood conservation interventions are likely to be most productive for this high-risk subset. Available evidence-based blood conservation techniques include (1) drugs that increase preoperative blood volume (eg, erythropoietin) or decrease postoperative bleeding (eg, antifibrinolytics), (2) devices that conserve blood (eg, intraoperative blood salvage and blood sparing interventions), (3) interventions that protect the patient's own blood from the stress of operation (eg, autologous predonation and normovolemic hemodilution), (4) consensus, institution-specific blood transfusion algorithms supplemented with point-of-care testing, and most importantly, (5) a multimodality approach to blood conservation combining all of the above.

Clinical Outcomes in Cardiac Surgery: Conventional Surgery versus Bloodless Surgery

Bleeding during and after cardiac operations and the effects of cardiopulmonary bypass hemodilution commonly result in blood transfusions. Excessive microvascular bleeding can result in re-exploration and prolonged hospitalization. Nearly 20% of all blood transfusions in the United States are associated with cardiac surgery. The risks associated with the use of allogeneic blood product transfusion include mistransfusion, immunologic complications, and transmission of infectious diseases. The large demand for blood products places significant pressure on the national blood supply, resulting in frequent shortages. The variability in transfusion practice of cardiac surgery patients suggests that sound blood management and a conservative approach to this population can result in reduced transfusions without increasing morbidity or mortality and avoiding complications associated with allogeneic blood transfusion.

Coagulation, fibrinolysis, and cell activation in patients and shed mediastinal blood during coronary artery bypass grafting with a new heparin-coated surface

OBJECTIVES

Heparin coating of the cardiopulmonary bypass circuit is shown to improve the biocompatibility of the surface. We have studied a new heparin surface, the Corline Heparin Surface, applied to a complete set of an extracorporeal device used during coronary artery bypass grafting in terms of activation of inflammation, coagulation, and fibrinolysis in patients and in shed mediastinal blood.

METHODS

Sixty patients scheduled for coronary artery bypass grafting were randomized to one of 3 groups with heparin-coated devices receiving either a standard, high, or low dose of systemic heparin or to an uncoated but otherwise identical circuit receiving a standard dose of systemic heparin. Samples were drawn before, during, and after the operation from the pericardial cavity and in shed mediastinal blood. No autotransfusion of shed mediastinal blood was performed.

RESULTS

The Corline Heparin Surface significantly reduced the activation of coagulation, fibrinolysis, platelets, and inflammation compared with that seen with the uncoated surface in combination with a standard dose of systemic heparin during cardiac surgery with cardiopulmonary bypass. Both a decrease and an increase of systemic heparin in combination with the coated heparin surface resulted in higher activation of these processes. A significantly higher expression of all studied parameters was found in the shed mediastinal blood compared with in systemic blood at the same time.

CONCLUSIONS

The Corline Heparin Surface used in cardiopulmonary bypass proved to be more biocompatible than an uncoated surface when using a standard systemic heparin dose. The low dose of systemic heparin might not be sufficient to maintain the antithrombotic activity, and the high dose resulted in direct cell activation rather than a further anti-inflammatory and anticoagulatory effect.

Fibrinolytic activity and postoperative salvaged untreated blood for autologous transfusion in major orthopaedic surgery

OBJECTIVE

To evaluate the fibrinolytic activity in a closed surgical wound, in postoperatively drained blood, and during autologous transfusion.

DESIGN

Prospective study.

SETTING

National hospital, Norway.

PATIENTS

9 patients operated on for thoracic scoliosis.

MAIN OUTCOME MEASURE

Concentrations of plasmin/antiplasmin (PAP), alpha2-antiplasmin, and D-dimers in drained, arterial, and mixed venous blood before, during, and after infusion of 10 ml/kg body weight of postoperatively drained, untreated blood.

RESULTS

In drained blood the concentration of alpha2-antiplasmin was 31% of the preoperative arterial control value. Together with the increased concentrations of PAP to 18076 microg/L and D-dimers to 126 mg/L, this indicates extensive fibrinolytic activity in the closed wound. The postoperative autologous transfusion of drained, untreated blood increased the concentration of PAP from 507 to 2453 microg/L and of D-dimer from 0.7 mg/L to 15.3 mg/L in systemic blood.

CONCLUSION

The systemic concentration of fibrin(ogen) degradation products, indicated by D-dimers, after recirculation of drained, untreated blood might impair coagulation. The extensive activation of plasmin might exhaust available alpha2-antiplasmin in the wound and result in postoperative rebleeding.

Unwashed shed blood infusion causes deterioration in right ventricular function after coronary artery surgery

We investigated right ventricular function after infusion of unwashed shed blood collected from mediastinal and chest tube drainage. Changes in thromboxane B2 (TXB2) and 6-keto-PGF1 alpha, which are stable metabolites of thromboxane A2 (TXA2) and prostacyclin respectively, were also investigated. The amount of infused shed blood was 484 +/- 76 ml (mean +/- SD). Right ventricular ejection fraction decreased rapidly after the infusion and did not return to its original level until 120 minutes later (P < 0.05). Mean pulmonary artery pressure rose after infusion of the shed blood (P < 0.05). The TXB2 level in the unwashed shed blood was about 20,000 times higher than the preoperative plasma level. The plasma TXB2 level at 30 minutes after the infusion was significantly elevated (P < 0.05), and at 120 minutes it had returned to the original level. Unwashed shed blood may contain vasoactive substances that induce the release of TXA2 and increase right ventricular afterload.

Autotransfusion in coronary artery bypass grafting: disparity in laboratory tests and clinical performance

OBJECTIVE

Autotransfusion during and after cardiac surgery is widely performed, but its effects on coagulation, fibrinolysis, and inflammatory response have not been known in detail.

METHODS

Hemostatic and inflammatory markers were extensively studied in 40 coronary artery bypass patients undergoing a consistent intraoperative and postoperative autotransfusion protocol. An identical autotransfusion protocol was applied to 4916 consecutive coronary patients and the overall clinical results were evaluated in this large patient population.

RESULTS

The autologous blood pooled before bypass remained nearly inactivated after storage. A slight elevation of thrombin-antithrombin complex and prothrombin fragment 1.2, as well as plasmin/alpha(2)-antiplasmin complex was found in the content of the extracorporeal circuit after surgery, indicating thrombin formation and fibrinolytic activity. Also some increase of beta-thromboglobulin was present. In the mediastinal shed blood, complete coagulation, as evidenced by the absence of fibrinogen, had taken place and all parameters described above were extremely elevated. However, no thrombin activity was detected. As for the inflammatory response, moderately increased levels of complement activation products, terminal complement complex, and interleukin-6 traced in the extracorporeal circuit reached very high levels in mediastinal shed blood. Autotransfusion of the residual extracorporeal circuit blood and the mediastinal drainage was followed by elevation of most of these markers in circulating plasma. On the other hand, no correlating harmful effects were recorded in the study patients or in the consecutive 4916 patients. Coagulation disturbances were rare and allogeneic transfusions were required in fewer than 4% of all patients.

CONCLUSIONS

The hemostatic and immunologic systems were moderately activated in the autologous blood remaining in the extracorporeal circuit, whereas the mediastinal shed blood was highly activated in all aspects. However, autotransfusion had no correlating clinical side-effects and the subsequent exposure to allogeneic blood products was minimal.

Safety and efficacy of shed mediastinal blood transfusion after cardiac surgery: a multicenter observational study. Multicenter Study of Perioperative Ischemia Research Group

OBJECTIVE

To examine the efficacy and safety of shed mediastinal blood (SMB) transfusion in preventing allogenic red blood cell (RBC) transfusion.

DESIGN

An observational clinical study.

SETTING

Twelve US academic medical centers.

PARTICIPANTS

Six hundred seventeen patients undergoing elective primary coronary artery bypass grafting.

INTERVENTIONS

Patients were administered SMB transfusion or not, according to institutional and individual practice, without random assignment.

MEASUREMENTS AND RESULTS

The independent effect of SMB transfusion on postoperative RBC transfusion was examined by multivariable modeling. Potential complications of SMB transfusion, such as bleeding and infection, were examined. Three hundred twelve of the study patients (51%) received postoperative SMB transfusion (mean volume, 554 +/- 359 mL). Patients transfused with SMB had significantly lower volumes of RBC transfusion than those not receiving SMB (0.86 +/- 1.50 v 1.08 +/- 1.65 units; p < 0.05). However, multivariable analysis showed that SMB transfusion was not predictive of postoperative RBC transfusion. Demographic factors (older age, female sex), institution, and postoperative events (greater chest tube drainage, lower hemoglobin level on arrival to the intensive care unit, and use of inotropes) were significant predictors of RBC transfusion. The volume of chest tube drainage on the operative day (707 +/- 392 v 673 +/- 460 mL; p = 0.30), reoperation for hemorrhage (3.1% v2.5%; p = 0.68), and overall frequency of infection (5.8% v 6.6%; p = 0.81) were similar between patients receiving and not receiving SMB, respectively. However, in patients who did not receive allogenic RBC transfusion, there was a significantly greater frequency of wound infection in the SMB group (3.6% v0%; p = 0.02).

CONCLUSION

These data suggest that SMB is ineffective as a blood conservation method and may be associated with a greater frequency of wound infection.

Greater increase in cytokine concentration after salvage with filtered whole blood than with washed red cells, but no difference in postoperative hemoglobin recovery

BACKGROUND

Inflammatory mediators are released in association with intraoperative and postoperative salvage of blood. Whether these mediators (cytokines) participate in the modulation of erythropoiesis or not has been investigated.

STUDY DESIGN AND METHODS

Twenty-seven patients who were to undergo total knee replacement surgery were randomly assigned to postoperative blood salvage with either filtered whole blood or washed red cells. Patients with postoperative blood loss <400 mL were considered a control group. The control group did not receive any transfusions. Plasma concentrations of the anaphylatoxin C3a, the C5b-9 terminal complement complex, and the cytokines interleukins 6 and 8, hemoglobin, reticulocytes, and red cell volume fraction in the patients were repeatedly analyzed before and after surgery.

RESULTS

Significantly increased concentrations of interleukin 6 appeared in all three groups, which was interpreted as a response to the surgical trauma. The increase was significantly greater in the group that received filtered whole blood after return of shed blood. The recovery of hemoglobin levels did not differ in the groups.

CONCLUSION

The transfusion of filtered whole blood leads to the formation of interleukin 6 in the circulation, but postoperative hemoglobin recovery was similar in all groups.

[Blood conservation effect and safety of shed mediastinal blood autotransfusion after cardiac surgery]

Autotransfusion of shed mediastinal blood after cardiac surgery has been used to reduce risks related to homologous blood transfusions. To document the efficacy and safety of autotransfusion, we compared clinical findings of 80 patients receiving shed mediastinal blood (autotransfusion group) with those of the control group of 52 patients. The amount of the autotransfusion was limited to 800 ml, given the potentially harmful effects of shed blood transfusion. The mean transfused shed volume was 314 +/- 236 ml (S.D.). The serum levels of FDP-E, D-dimer and TAT after autotransfusion were higher in the autotransfusion group than in the control group (p = 0.01, p = 0.0004, p = 0.001, respectively). However, postoperative blood loss and the rate of reexploration for bleeding were similar in the two groups. The patients receiving blood products were fewer in the autotransfusion group than those in the control group (21% vs 44%; p = 0.005). Autotransfusion did not increase postoperative complications, including infection. Thus, although autotransfusion of mediastinal shed blood has the potential to affect hemostasis, unless the amount of autotransfusion exceeds 800 ml, it appears that this method is clinically safe and effective as a mean of blood conservation.

The inflammatory cytokine response after autotransfusion of shed mediastinal blood

BACKGROUND

The inflammatory response in patients undergoing cardiac surgery with cardiopulmonary bypass is well known and increased levels of inflammatory cytokines have been shown. High levels of cytokines have been reported in blood drained from the surgical field. The present study aimed to elucidate whether autotransfusion of shed mediastinal blood in itself causes increased cytokine levels in coronary artery bypass graft (CABG) patients.

METHODS

A prospective, randomized controlled study was performed in 23 patients having elective uncomplicated CABG. Autotransfusion of shed mediastinal blood was done every hour for 18 h in group I. In group II, the shed mediastinal blood was accumulated for 4 h in the cardiotomy reservoir and then autotransfused every hour for the next 14 h. Plasma levels of tumour necrosis factor-alpha (TNFalpha) and interleukin (IL)-1alpha, IL-1beta, IL-6 were measured. In vitro study of cytokine production was performed with or without stimulation (phytohaemagglutinin (PHA) and Escherichia coli (E. coli) lipopolysaccharide (LPS)).

RESULTS

We found high levels of IL-6 in the shed mediastinal blood. However, autotransfusion of shed mediastinal blood did not lead to increased level of cytokines (TNFalpha, IL-1alpha, IL-1beta and IL-6) in plasma in group I nor in group II. In vitro study showed activation of the leucocytes in the shed mediastinal blood with a significantly increased production of TNFalpha and IL-6 both in the stimulated and non-stimulated samples.

CONCLUSION

Shed mediastinal blood contains high levels of IL-6. However, autotransfusion of shed mediastinal does not cause measurable elevations in plasma levels of IL-6. In vitro study shows that autotransfusion activates leucocytes, which may enhance production of inflammatory cytokines.

Rheological properties and function of blood cells in stored bank blood and salvaged blood

The technique involving filtration of diluted blood enables the separate analysis of the flow properties of different cell subpopulations. This study was designed to assess the changes occurring in the flow properties and function of blood cells in stored bank blood and salvaged blood compared to patient blood in a given clinical situation. We measured hydrogen peroxide production by neutrophils and the filterability, through 5 microm Nucleopore filters, of isolated red blood cells and of diluted blood. Samples were obtained from patients undergoing aortic surgery and blood intended for transfusion: either salvaged during surgery or stored bank blood. Both salvaged and bank blood were much less filterable than patient blood, with reduced deformability of both red and white blood cells. However, salvaged blood contained highly activated neutrophils with a prolonged transit time of the 'fast-flowing' cells in the analysis compared to bank blood. Bank blood contained significantly more particles which acted as pore-blockers. Cells in bank and salvaged blood therefore have markedly abnormal flow and biochemical properties compared to patient blood.

Comprehensive multimodality blood conservation: 100 consecutive CABG operations without transfusion

BACKGROUND

Despite the recent introduction of a number of technical and pharmacologic blood conservation measures, bleeding and allogeneic transfusion remain persistent problems in open heart surgical procedures. We hypothesized that a comprehensive multimodality blood conservation program applied algorithmically on the basis of bleeding and transfusion risk would provide a maximum, cost-effective, and safe reduction in postoperative bleeding and allogeneic blood transfusion.

METHODS

One hundred consecutive patients undergoing coronary artery bypass grafting were prospectively enrolled in a risk factor-based multimodality blood conservation program (MMD group). To evaluate the relative efficacy and safety of this comprehensive approach, comparison was made with a similar group of 90 patients undergoing coronary artery bypass grafting to whom the multimodality blood conservation program was not applied but in whom an identical set of transfusion guidelines was enforced (control group). To evaluate the cost effectiveness of the multimodality program, comparison was also made between patients in the MMD group and a consecutive series of contemporaneous, diagnostic-related group-matched patients.

RESULTS

One hundred consecutive patients in the MMD group underwent coronary artery bypass grafting without allogeneic transfusion. This compared favorably with the control population in whom a mean of 2.2 +/- 6.7 units of allogeneic blood was transfused per patient (34 patients [38%] received transfusion). In addition, the volume of postoperative blood loss at 12 hours in the control group was almost double that of the MMD group (660 +/- 270 mL versus 370 +/- 180 mL [p < 0.001]). Total costs for the MMD group in each of the three major diagnostic-related groups were equivalent to or significantly less than those in the consecutive series of diagnostic-related group-matched patients.

CONCLUSIONS

Comprehensive risk factor-based application of multiple blood conservation measures in an optimized, integrated, and algorithmic manner can significantly decrease bleeding and need of allogeneic transfusion in coronary artery bypass grafting in a safe and cost-effective manner.

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.

Reduction in requirements for allogeneic blood products: nonpharmacologic methods

BACKGROUND

Various strategies have been proposed to decrease bleeding and allogeneic transfusion requirements during and after cardiac operations. This article attempts to document the usefulness, or lack thereof, of the nonpharmacologic methods available in clinical practice.

METHODS

Blood conservation methods were reviewed in chronologic order, as they become available to patients during the perisurgical period. The literature in support of or against each strategy was reexamined critically.

RESULTS

Avoidance of preoperative anemia and adherence to published guidelines for the practice of transfusion are of paramount importance. Intraoperatively, tolerance of low hemoglobin concentrations and use of autologous blood (predonated or harvested before bypass) will reduce allogeneic transfusions. The usefulness of plateletpheresis and retransfusion of shed mediastinal fluid remains controversial. Intraoperatively and postoperatively, maintenance of normothermia contributes to improved hemostasis.

CONCLUSIONS

Several approaches have been shown to be effective. An efficient combination of methods can reduce, and sometimes abolish, the need for allogeneic blood products after cardiac operations, inasmuch as all those involved in the care of cardiac surgical patients adhere thoughtfully to existing transfusion guidelines.

Adverse effects of postoperative infusion of shed mediastinal blood

BACKGROUND

Postoperative infusion of shed mediastinal blood has been used in an effort to decrease blood usage after cardiac operations. Recent experience has suggested that this practice may actually lead to a delayed increase in bleeding.

METHODS

In a prospective, randomized study, 40 patients undergoing coronary artery bypass grafting with shed mediastinal blood collected in a cardiotomy reservoir were divided into two equal groups and studied during their first 4 hours in the intensive care unit. Shed mediastinal blood was directly infused in group I (n = 20), whereas in group II (n = 20), it was not. In group II, if a sufficient volume of red cells was present to allow processing (n = 5), washed red cells were infused. Variables studied before and after infusion were the amount of blood lost and infused, homologous blood transfused, complete blood count and differential, serum fibrinogen, fibrin split products, D-dimers, clotting factors, prothrombin time, activated partial thromboplastin time, thromboelastograms, plasma-free hemoglobin, complement factors C3 and C4, creatine kinase and its MB isoenzyme, and body temperature.

RESULTS

After infusion of shed mediastinal blood, elevated levels of fibrin split products and D-dimers were found in significantly more patients in group I. The thromboelastogram index was normal in 76% of patients in group II but in only 12.5% in group I. Group I also had an increase in band neutrophils, a greater number of febrile patients, higher serum levels of creatine kinase, its MB isoenzyme, and plasma-free hemoglobin, and greater blood loss during hours 3, 4, and 5 in the intensive care unit. The volume of red cells in shed mediastinal blood (hematocrit, 9% to 10%) was small, resulting in clinically insignificant autotransfusion when infused directly, and insufficient for cell processing in most patients.

CONCLUSIONS

These data support those in previous studies that direct infusion of shed mediastinal blood does not save substantial amounts of autologous red cells and can cause a delayed coagulopathy and other adverse effects that may be harmful to patients postoperatively.

Systemic blood activation with open and closed venous reservoirs

In 20 patients undergoing coronary artery bypass grafting, we studied prospectively systemic blood activation, blood loss, and the need for donor blood when using an extracorporeal circuit equipped at random with one of two different venous reservoirs. In 10 patients we used an open venous reservoir system (ORS) consisting of a hard shell venous reservoir with an integral cardiotomy filter, and in 10 patients we used a closed reservoir system consisting of a collapsible venous reservoir and separate cardiotomy reservoir. Concentrations of complement 3a, elastase, thromboxane B2, and fibrin degradation products showed a biphasic course, especially in ORS patients. During bypass, we observed a first peak of levels of complement 3a, thromboxane B2, fibrin degradation products, and elastase, which was higher in ORS patients than in patients with the closed system, because their blood continuously contacted the foreign materials of the filter and air in the open reservoir, which was avoided in the closed reservoir. Intensive blood-foreign material contact also caused the highest (p < 0.05) hemolysis in ORS patients. The larger amount of hemolytic products in ORS patients theoretically resulted in a temporary decrease in capacity of their Kupffer cells to clear endotoxin released after aortic declamping. This theory might explain the significantly (p < 0.01) higher second peak of activated products after declamping that was observed in ORS patients. Due to increased blood activation, the largest (p < 0.001) amount of shed blood loss, greatest (p < 0.05) need for colloid-crystalloid infusion, and largest (not significant) need for donor blood were found in ORS patients (0.8 +/- 0.4 versus 0.2 +/- 0.2 units of packed cells).(ABSTRACT TRUNCATED AT 250 WORDS)