Tissue-type plasminogen activator and fibrin monomers synergistically cause platelet dysfunction during retransfusion of shed blood after cardiopulmonary bypass

Cell salvage processing of residual cardiopulmonary bypass volume in minimally invasive cardiac surgery

Several reports demonstrated positive effects of processing residual cardiopulmonary bypass volume using a cell salvage device in conventional open heart surgery via sternotomy on hemostasis. The present study aimed to investigate whether cell salvage processing has the same effects on postoperative blood loss and transfusion in minimally invasive cardiac surgery. Between July 2015 and April 2018, 80 consecutive patients undergoing minimally invasive aortic valve replacement via right anterolateral minithoracotomy were enrolled in the present study. Perioperative outcomes and coagulation data of 40 patients who were retransfused with processed cardiopulmonary bypass volumes were compared with those of 40 patients receiving unprocessed residual blood (control group). Postoperative blood loss in patients receiving processed residual blood was significantly less than that in the control group at 6 h (115 ± 50 vs. 73 ± 33 ml, p < 0.001) and 12 h (167 ± 70 vs. 125 ± 67 ml, p = 0.009) after surgery, and the rate of fresh frozen plasma use after surgery was significantly reduced in patients receiving processed residual blood (18 vs. 0%, p = 0.012). In conclusion, processing of residual cardiopulmonary bypass volume reduced postoperative blood loss and postoperative use of fresh frozen plasma and could be useful for hemostasis in minimally invasive cardiac surgery.

Lessons learned on the path to a healthier brain: dispelling the myths and challenging the hypotheses

Neurologic dysfunction remains the most significant complication associated with cardiopulmonary bypass (CPB). The insidious change of cognitive decline has been perceived as a key factor that has contributed to the shift to percutaneous intervention for coronary disease. Current neuropsychologic testing provides the most sensitive means of demonstrating clinically relevant cerebral damage of this nature. Through extensive experience in randomized clinical trials of over 900 patients undergoing CPB, our team has addressed several key hypotheses related to the embolic/ischemic nature of cerebral injury in cardiac surgery, using this testing. In the first temperature study, patients randomized to hypothermia with passive re-warming had a lower incidence of neurocognitive deficit when compared with those patients who were actively re-warmed to 37°. In order to clarify the role of the hypothermia as opposed to the re-warming process, a second temperature study was completed. In the hypothermic group, patients were cooled and maintained at 34° with no active re-warming whereas, in the normothermic group, the patients were kept at 37° throughout the perioperative period. No difference in neurocognitive outcome in the two groups was seen, implying that the benefit seen in the first temperature study was related not to the hypothermia, but rather to the absence of active re-warming. In the cardiotomy study, patients were randomized to either a control group in which their cardiotomy blood was returned unprocessed, or a treatment group in which this blood was sequestered and processed with centrifugal washing and fat filtration. No significant difference in neurocognitive outcome was found in these two groups. On the other hand, there was a significant increase in bleeding and transfusion requirements in the treatment group. Many of our daily practices in CPB management are based upon assumptions from observational studies without sound reference to evidence-based medicine. Our recent studies have challenged our assumptions related to ischemia and embolic events during CPB. They have also confirmed that, when high standards in trial design are applied, the results can have universal implications in terms of our practice. Perfusion (2007) 22, 153—160.

2011 update to the Society of Thoracic Surgeons and the Society of Cardiovascular Anesthesiologists blood conservation clinical practice guidelines

BACKGROUND

Practice guidelines reflect published literature. Because of the ever changing literature base, it is necessary to update and revise guideline recommendations from time to time. The Society of Thoracic Surgeons recommends review and possible update of previously published guidelines at least every three years. This summary is an update of the blood conservation guideline published in 2007.

METHODS

The search methods used in the current version differ compared to the previously published guideline. Literature searches were conducted using standardized MeSH terms from the National Library of Medicine PUBMED database list of search terms. The following terms comprised the standard baseline search terms for all topics and were connected with the logical 'OR' connector--Extracorporeal circulation (MeSH number E04.292), cardiovascular surgical procedures (MeSH number E04.100), and vascular diseases (MeSH number C14.907). Use of these broad search terms allowed specific topics to be added to the search with the logical 'AND' connector.

RESULTS

In this 2011 guideline update, areas of major revision include: 1) management of dual anti-platelet therapy before operation, 2) use of drugs that augment red blood cell volume or limit blood loss, 3) use of blood derivatives including fresh frozen plasma, Factor XIII, leukoreduced red blood cells, platelet plasmapheresis, recombinant Factor VII, antithrombin III, and Factor IX concentrates, 4) changes in management of blood salvage, 5) use of minimally invasive procedures to limit perioperative bleeding and blood transfusion, 6) recommendations for blood conservation related to extracorporeal membrane oxygenation and cardiopulmonary perfusion, 7) use of topical hemostatic agents, and 8) new insights into the value of team interventions in blood management.

CONCLUSIONS

Much has changed since the previously published 2007 STS blood management guidelines and this document contains new and revised recommendations.

Strategy of transfusion in cardiac surgery: limits of hematocrit and how much is too low?

The use of blood and blood products in cardiac surgery is higher than necessary and a reduction is imperative due to complications and costs. Hemodilution is unavoidable in cardiopulmonary bypass and is the most likely pitfall when evaluating transfusion needs. Even patients with coexisting cardiovascular diseases tolerate perioperative hemodilution better than most anticipate. Hemodynamic monitoring is important to evaluate the association between hemoglobin level and organ function. Use of both mechanical and medical blood conservation strategies is required to reduce blood transfusion, and most of the methods have a positive cost-effectiveness and cost-benefit. By using the right strategy and policy, transfusion of blood and blood products can be reduced to less than 5% of cardiac patients.

Managing fibrinolysis without aprotinin

Cardiopulmonary bypass increases perioperative bleeding and produces a consumptive coagulopathy, which is defined as the simultaneous production of thrombin and fibrinolysis. Thrombin formation and fibrinolysis primarily occur in the surgical wound and peak at the time heparin is reversed by protamine. Neither aprotinin nor lysine analogs successfully control bleeding in many complex procedures, reoperations, aortic resections, or in implantations of mechanical circulatory devices. This analysis reviews the mechanisms involved and current treatment protocols, with the conclusion that changes in treatment protocols rather than use of a specific anti-fibrinolytic drug may provide better control of bleeding in these patients.

Intraoperative blood salvage and retransfusion from citrate treated wounds is safe and feasible

OBJECTIVES

Allogenic blood transfusions are associated with increased morbidity and mortality in surgical patients. The study objective was to investigate the feasibility and safety of intraoperative autotransfusion of unwashed shed whole blood using a novel method.

DESIGN

Twenty pigs were randomised to autotransfusion or crystalloid volume replacement. In two separate surgical wounds, the surfaces and 400 ml of shed blood were treated in situ with citrate, delivered with an equipment transforming suction to positive pressure. Central haemodynamics were monitored with a pulmonary artery catheter. Effects on oxygen-carrying capacity, formed blood elements, haemolysis, inflammation, metabolism, and coagulation were evaluated with biochemical analyses.

RESULTS

No clinically relevant adverse effects on haemodynamics were encountered, apart from a decrease in cardiac output and mixed venous saturation similar to that in control animals. Haemoglobin level was better preserved in the autotransfused group (97 vs. 86 g/L, p=0.0007). There were no major differences in biochemical variables and no macroscopic clot formation precluding autotransfusion.

CONCLUSIONS

The technique was safe and feasible for intraoperative blood salvage and autotransfusion. Haemodynamics and biochemical variables were similar to controls. The technique warrants further studies in humans, as it may contribute towards a reduction of allogenic blood transfusions.

A systematic review of biocompatible cardiopulmonary bypass circuits and clinical outcome

This systematic review and meta-analysis explores the clinical efficacy of biocompatible surfaces for cardiopulmonary bypass in adults. Thirty-six randomized controlled trials were retrieved for a total of 4360 patients. Patients treated with biocompatible circuits had a lower rate of packed red cells transfusions and atrial fibrillation, and shorter durations of stay in the intensive care unit. When the analysis was limited to high-quality studies, only a reduction in atrial fibrillation rate and a shorter stay in the intensive care unit remained significantly associated with the use of biocompatible surfaces. Using biocompatible surfaces without other measures to contain blood activation results in a limited clinical benefit.

Influence of early re-infusion of autologous shed mediastinal blood on clinical outcome after cardiac surgery

Various strategies have been proposed to decrease allogeneic blood transfusion requirements after cardiac surgery. The aim of the study was to evaluate the efficacy of collected and re-infused autologous shed mediastinal blood on a patient's postoperative course. Ninety patients who underwent heart surgery with cardiopulmonary bypass (CPB) were studied. The patients were divided into two groups: Group 1 (n=41) received the centrifuged autologous shed mediastinal blood collected from the cardiotomy reservoir 4 hours after surgery; in Group 2 (n=49) all shed mediastinal blood was discarded (control group). Haemoglobin (Hb), haematocrit (Hct), C-reactive protein values, and leucocyte count were compared before surgery, at 4 h and 20 h after surgery, and on the fifth postoperative day. We have measured serum procalcitonin (PCT) concentration at 4 h and 20 h after CPB. We assessed drained blood loss within 20 postoperative hours. Leucocyte count, Hb, Hct values, C-reactive protein, and procalcitonin concentration did not differ between the groups before and at 4 h after surgery. Hb, Hct level, and leucocyte count were similar at 20 hours and on the fifth day after surgery. At 20 hours after surgery, an increase of serum PCT concentration (>0.5-2 ng/mL) was more frequent in Group 2 (58.3% vs. 33.3%; p = 0.03). On the fifth postoperative day, C-reactive protein concentration was lower in Group 1 (71.74 +/- 15.23; p <0.01) compared to Group 2 (93.53 +/- 20.3). Postoperative blood loss did not differ between the groups. Requirement for allogeneic blood transfusion was significantly lower in Group 1 (14.6% vs. 38.8%; p < 0.02). Patients in Group 1 developed less infective complications compared with Group 2 (2.4% and 16.3%, respectively; p < 0.05). The length of postoperative in-hospital stay was shorter in Group 1 compared with Group 2 (9.32 +/- 2.55 and 16.45 +/- 6.5, respectively; p < 0.05). We conclude that postoperative re-infusion of autologous red blood cells processed from shed mediastinal blood did not increase bleeding tendency and systemic inflammatory response and was effective in reducing the requirement for allogeneic transfusion, the rate of infective complications and the length of postoperative in-hospital stay.

Minimally Invasive Closed Circuit Versus Standard Extracorporeal Circulation for Aortic Valve Replacement

BACKGROUND

The purpose of this study was to evaluate the safety and clinical results of aortic valve replacement performed with minimally invasive closed circuit extracorporeal circulation technique (MECC system) versus standard cardiopulmonary bypass.

METHODS

Forty consecutive patients undergoing isolated aortic valve replacement at a single institution were randomly assigned to either miniaturized closed circuit cardiopulmonary bypass with the Maquet-Cardiopulmonary (Rastatt, Germany) minimal extracorporeal circulation (MECC) system (study group B, n = 17) or standard cardiopulmonary bypass (control group A, n = 23). The MECC system is a low priming circuit without blood-air interface. Technical feasibility, in particular the potential entry of air in the circuit, and clinical results were prospectively evaluated.

RESULTS

Demographic characteristics and surgical data were similar in both groups. Patients in the study group showed reduced chest tube drainage (217 +/- 62 mL vs 420 +/- 219 mL, p < 0.05) and blood transfusion requirements (5.1% vs 43.4%, p < 0.02) compared with patients in the control group. Moreover, the study group showed significantly higher time course of hematocrit at all time points during the operation and longer hospital stay (p < 0.02) than the control group; similarly, in the study group patients' platelet count in intensive care unit admission was significantly higher than the control group (140 +/- 29 x 10(9)/L vs 119 +/- 37 x 10(9)/L, p < 0.05). Peak postoperative troponin C release was significantly lower in the study group (4.74 +/- 2.82 vs 8.43 +/- 6.25 ng/dL, p < 0.033). One patient undergoing the MECC system operation showed a major neurologic event on postoperative day four, which was probably secondary to severe aortic calcification.

CONCLUSIONS

The MECC system is suitable for aortic valve replacement and provides better clinical results than standard cardiopulmonary bypass as regards blood transfusion requirements, platelets consumption, and myocardial damage.

Hemostatic defect in baboons autotransfused treated plasma to simulate shed blood

BACKGROUND

Nonwashed shed blood may contain products of clotting and fibrinolytic, and antifibrinolytic substances. This study was done to determine how autotransfusion of nontreated plasma and plasma treated with urokinase with and without aprotinin affected hemostasis in healthy baboons.

METHODS

A 500-mL volume of blood was collected from the baboon, a 250-mL volume of plasma was isolated, and the RBCs were reinfused. Three baboons were autotransfused untreated plasma. Four baboons received plasma that had been treated with 3000 IU/mL urokinase at +37 degrees C for 30 minutes. Eight baboons received plasma that had been treated first with urokinase 3000 IU/mL at +37 degrees C for 30 minutes and then with aprotinin (1000 KIU/mL). Bleeding time, fibrinogen degradation products (FDP), D-dimer, and alpha-2 antiplasmin levels were measured.

RESULTS

During the 4-hour period following autotransfusion of the urokinase-aprotinin-treated plasma, the levels of D-dimer and FDP were significantly higher and fibrinogen and alpha-2 antiplasmin levels were significantly lower than those levels seen after the autotransfusion of nontreated plasma. FDP and D-dimer levels showed significant positive correlations with prothrombin time (PT) and activated partial thromboplastin time (aPTT). A significant negative correlation was observed between thrombin time (TT) and fibrinogen level. A significant positive correlation was observed between bleeding time and D-dimer level and a significant negative correlation between the bleeding time and the fibrinogen level.

CONCLUSIONS

The infusion of a volume of urokinase or urokinase-aprotinin treated autologous plasma equivalent to 15% of the blood volume was not associated with a bleeding diathesis in healthy baboons.

Strategies to reduce hemostatic activation during cardiopulmonary bypass

INTRODUCTION

We evaluated whether a modified protocol for cardiopulmonary bypass (CPB) could reduced the systemic hemostatic activation associated with this procedure.

MATERIALS AND METHODS

The in vivo rates of thrombin, fibrin, plasmin and D-dimer generation were determined in each subject during CPB using measured levels of hemostatic factors combined with a computer model of the cardiovascular and hemostatic systems. A standard CPB group using uncoated circuits, standard heparin levels and direct shed blood reinfusion (n=9) was compared to a modified CPB group using heparin-coated circuits, shed blood collection, washing and reinfusion post-operatively, lower heparin levels and epsilon-amino-caproic acid (n=10).

RESULTS AND CONCLUSIONS

Standard CPB increased average thrombin generation 9-fold, decreased fibrin generation 2-fold, increased plasmin generation 11-fold and increased fibrin degradation and D-dimer generation 19-fold. During CPB in the modified group thrombin generation was not increased beyond surgical levels, lower heparin concentrations allowed each thrombin to make more fibrin prior to inhibition, while fibrin degradation was suppressed by epsilon-amino-caproic acid. At baseline for every 100 fibrins formed only 1-2 were degraded to D-dimer. During standard CPB for every 100 fibrins generated on average 34 fibrins were degraded with some subjects showing a net fibrin loss. In contrast, in the modified CPB group for every 100 fibrins formed only 4 fibrins were degraded (p<0.0001 vs. standard group). Kinetic modeling of hemostasis in individual patients showed that a modified CPB protocol could reduce excessive thrombin generation during CPB and suppress fibrin degradation moving hemostatic regulation back towards normal.

Tranexamic acid and early saphenous vein graft patency in conventional coronary artery bypass graft surgery: a prospective randomized controlled clinical trial

OBJECTIVE

Use of antifibrinolytic agents reduces the risk of bleeding and decreases the need for blood product use in patients undergoing cardiac surgery. The purpose of this study was to determine whether perioperative use of tranexamic acid decreases the rate of saphenous vein graft patency in the early postoperative period after conventional coronary artery bypass grafting surgery.

METHODS

A total of 312 patients scheduled for elective coronary artery bypass grafting surgery with cardiopulmonary bypass were randomized to receive either tranexamic acid 100 mg/kg (n = 147) or placebo (n = 165) in a double-blinded fashion before the initiation of cardiopulmonary bypass. Saphenous vein graft patency was assessed with magnetic resonance imaging 5 to 30 days after surgery.

RESULTS

Both groups were comparable with respect to baseline demographic data and surgical characteristics. A total of 237 (76%) patients underwent magnetic resonance imaging assessment. A total of 297 saphenous vein grafts were performed and 253 (85.2%; 95% confidence interval, 83.5%-86.9%) were seen in the tranexamic acid group, and 265 saphenous vein grafts were performed and 231 (87.2%; 95% confidence interval, 85.5%-88.9%) were seen in the placebo group (P = .4969). The blood loss and blood product transfusion rates in the tranexamic acid group were significantly lower than in the placebo group. There was no difference between groups with respect to postoperative morbidity and mortality.

CONCLUSIONS

The administration of tranexamic acid before cardiopulmonary bypass did not seem to compromise early venous graft patency rates but reduced perioperative blood product transfusion rates. Consequently, tranexamic acid could be advocated for routine use in patients undergoing conventional coronary artery bypass grafting surgery.

Autotransfusion of Shed Mediastinal Blood *

RATIONALE

After the introduction of autotransfusion of shed mediastinal blood following cardiac surgery, the incidence of mediastinitis increased. The role of autotransfusion in the increased occurrence of this serious complication was examined.

METHODS

Using a case-control design, the preoperative, intraoperative, and postoperative characteristics of 11 patients with mediastinitis were compared to those of 33 randomly selected patients undergoing cardiac surgery between September 1, 2000, and April 15, 2001 (control subjects).

RESULTS

Patients with mediastinitis were significantly more likely to have a body mass index > 30 (unadjusted odds ratio [OR], 9.9; 95% confidence interval [CI], 2.3 to 42.5), to have received antibiotic therapy during the 2 weeks prior to cardiac surgery (OR, 12.0; 95% CI, 1.1 to 131), or to have required re-exploration within 24 h of the original operation (OR, 8.3; 95% CI, 1.8 to 39). Patients with mediastinitis had 3.4 known risk factors for mediastinitis, compared to only 1.4 risk factors per control subject (p = 0.0001), and longer duration of autotransfusion. After adjustment for other risk factors, autotransfusion for > 6 h was significantly associated with the development of mediastinitis (adjusted OR, 11.9; 95% CI, 1.4 to 97.2).

CONCLUSION

Retransfusion of shed mediastinal blood for > 6 h after cardiac surgery was an independent risk factor for mediastinitis.

Physiological coagulation can be maintained in extracorporeal circulation by means of shed blood separation and coating

OBJECTIVE

Conventional extracorporeal circulation results in an activation of coagulation cascades. Coating of extracorporeal circulation tubes as well as avoidance of shed blood recirculation have been shown to reduce these phenomena. We evaluated a new shed blood separation system (AVANT D 970) utilizing a coated cardiopulmonary bypass tube system (PHISIO).

METHODS

Forty patients (62 +/- 10 years) underwent isolated coronary revascularization. Four groups (n = 10/group) were defined: no extracorporeal circulation, conventional uncoated extracorporeal circulation, uncoated extracorporeal circulation with shed blood separation, and coated extracorporeal circulation with shed blood separation. Thrombin-antithrombin complex and free Hb were analyzed and statistically compared.

RESULTS

Conventional extracorporeal circulation exhibited the highest intraoperative activation of coagulation (thrombin-antithrombin complex: extracorporeal circulation, 31.1 +/- 15.8 microg/L; uncoated extracorporeal circulation with shed blood separation, 15.3 +/- 7.8 microg/L; coated extracorporeal circulation with shed blood separation, 8.1 +/- 4.8 microg/L; no extracorporeal circulation, 2.4 +/- 0.6 microg/L; P <.05 extracorporeal circulation vs all others) and red blood cell damage (free Hb: extracorporeal circulation, 16.8 +/- 11.4 micromol/L; uncoated extracorporeal circulation with shed blood separation, 10.3 +/- 3.5 micromol/L; coated extracorporeal circulation with shed blood separation, 6.8 +/- 2.9 micromol/L; no extracorporeal circulation, 3.4 +/- 1.1 micromol/L; P <.05 extracorporeal circulation vs no extracorporeal circulation, coated extracorporeal circulation with shed blood separation). Coated extracorporeal circulation with shed blood separation showed only slight activation and cell trauma, which did not differ significantly from no extracorporeal circulation.

CONCLUSIONS

Combination of coating and avoidance of shed blood recirculation maintained physiological coagulation levels and markedly reduced red blood cell trauma in extracorporeal circulation procedures. These combined modalities may therefore offer an alternative for off-pump procedures in patients with contraindications for conventional extracorporeal circulation.

Cardiopulmonary bypass technology transfer: musings of a cardiac surgeon

The development of cardiopulmonary bypass (CPB) has been one of the greatest technical advancements in cardiovascular medicine. With heparin anticoagulation, this device can safely replace the circulatory and gas-exchanging functions of the heart and lung, facilitating complex cardiac operations. Limitations still exist however, related to blood reactions at the biomaterial surface, such as cell activation, inflammation and low-grade thrombosis. In this brief review, the thought processes which paralleled the development of CPB biocompatible surfaces such as heparin-coating, will be explored, as well as current theories on the suspected mechanisms by which heparin-coated surfaces act as an anti-inflammatory device during CPB. Results with new surfaces for CPB designed to capitalize on superior protein adsorption properties, such as surface modifying additive (SMA) and poly (2-methoxyethylacrylate) (PMEA), will also be described. Finally, the significance of biomaterial-independent blood activation will be discussed, emphasizing the current need to develop strategies utilizing optimal biomaterials, modified surgical technique and pharmacologic therapy to minimize the systemic complications of CPB.

Intra-operative autologous blood management

The evolution of cardiac surgery has been accompanied by a wide variety of techniques and equipment available for blood conservation. It has also given us data that allows identification of preoperative risk factors for transfusion needs in other surgical specialties. There is however great diversity of opinion as to how this technology should be applied. Examples can be found in the literature of discrepancies between countries but also individual institutions . The authors encounter differences in opinion between practitioners regularly. The authors believe that the variance in opinion may be based on the experiences of single techniques and that a broader depth of practice is required to achieve best practices for intra-operative transfusion management. The most performed procedure in our experience is red cell salvage and processing with a cell-washing device (CS). There are two primary issues related to CS, cost and reduction in allogenic blood exposure. A recent meta-analysis has shown that cell salvage in orthopedic surgery decreases the proportion of patients requiring allogeneic blood transfusion peri-operatively, but post-operative cell salvage is only marginally effective in cardiac surgery. There are close analogies to be drawn from issues surrounding the whole picture of transfusion. Medical practice guidelines are frequently promoted as a way to improve the cost-effectiveness of healthcare. But non-compliance with guidelines is still a major issue. Guiding the decision to transfuse or autotransfuse can improve transfusion practices, but effective processes must first identify problem(s) in transfusion practice and then include the attending medical practitioner as an educational target. Process improvements that have been shown to be effective include, briefly meeting one-on-one with physicians, teaching at scheduled conferences, making daily clinical rounds of patients who receive transfusion, concurrently reviewing orders for transfusion before issue of the blood product, and installing algorithms and guidelines in the operating room. Transfusion practices improved with these process improvements. The success of a change of practice patterns relies on hospital administration, education and feedback, written and immediately available guidelines, employment of specially trained personnel, and establishing long-standing actions. It is the authors' observation that the success of an intra-operation blood management program is twofold, early identification of patients and a multi-team approach of Surgeon, Haematologist, Transfusion services, Anaesthetist and Perfusionist. This team approach offers far greater depth for management of intra-operative blood conservation and transfusion practice. Interventions must be patient specific and targeted toward the best possible patients outcome.

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.

Haemolysis during cardiopulmonary bypass: how to reduce the free haemoglobin by managing the suctioned blood separately

During cardiopulmonary bypass (CPB) the collection of the patient's blood from the operating area is of fundamental importance. This blood is collected in the cardiotomy reservoir using field suckers and can be managed in different ways. It can be filtered in the cardiotomy reservoir and redirected to the venous reservoir, then oxygenated and returned to the patient, or it can be managed separately: collected in the cardiotomy reservoir, treated at the end of the operation and only after this, returned to the patient. The aim of this study is to determine in vivo the effect of a separate management of the suction blood from the operative field, using the Avant D903 oxygenator (Dideco, Mirandola, Italy). Twenty-one patients undergoing coronary artery bypass graft surgery with CPB were selected and put into two groups at random. In the control group (n = 10) the suction blood in the cardiotomy reservoir was filtered and immediately redirected into the venous reservoir, oxygenated and returned to the patient. In the study group (n = 11) the suctioned blood was collected in the D903 Avant's (Dideco) cardiotomy reservoir and returned to the patient only after having been washed at the end of the operation, using a Compact Advanced (Dideco), as required. Clinical data demonstrated that while in the study group it was possible to keep the free plasma haemoglobin (FPH) concentrations the same as at the beginning, in the control group there was a significant increase in FPH from 5.0 +/- 3.5 mg/dl (baseline) to 37 +/- 16.7mg/dl (120min after CPB).

Autotransfusion in cardiac surgery

There are a number of problems with allogeneic blood transfusion. Some of these problems are defined and can be quantified, such as the problem of rising cost or the risk of viral infection, but some of the problems are not well defined and it is only outcome data that point to allogeneic blood transfusion contributing to patient mortality and morbidity. Autotransfusion includes any technique in which the patient's own blood is collected, processed and stored, followed by reinfusion when circumstances dictate. In the perioperative period of cardiac surgery, a number of techniques are recognized as useful in this context. Preoperative autologous donation, with or without erythropoietin supplementation, intraoperative acute normovolaemic haemodilution, intraoperative cell salvage, postoperative cell salvage (reinfusion of shed mediastinal blood) and platelet rich plasmapheresis are all techniques which are used with more or less enthusiasm to reduce the need for an allogeneic blood transfusion. Modification of the priming technique of the cardiopulmonary bypass circuit using an autologous blood prime is included in this review even though it does not fall strictly within the definition of autotransfusion. Although autotransfusion is not the answer to every problem, there is no doubt that it should play a significant part in the strategy of blood conservation.

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.

Platelets and soluble fibrin promote plasminogen activation causing downregulation of platelet glycoprotein Ib/IX complexes: protection by aprotinin

Blood loss during and after open-heart surgery with cardiopulmonary bypass (CPB) is largely caused by platelet dysfunction. Previous studies indicate that plasmin can induce platelet dysfunction and affect primary hemostasis by proteolytic degradation and/or redistribution of essential platelet membrane glycoprotein complexes such as the glycoprotein Ib/IX complex. In this study, we present a model for plasmin generation localized on the platelet surface. Platelets treated with soluble fibrin or platelets in a mixture with soluble fibrin, t-PA, and plasminogen caused a significantly increased plasmin generation (p<0.01), dependent on t-PA, soluble fibrin, and platelet concentration. The plasmin generation resulted in a downregulation of platelet membrane glycoprotein Ib/IX glycoprotein complexes. Finally, we demonstrated that inhibitors of fibrinolysis, such as %2-antiplasmin, tranexamic acid, and aprotinin, can inhibit plasmin activity in the fluid phase. The downregulation of platelet glycoprotein Ib/IX complexes, however, was only prevented by aprotinin and not by alpha2-antiplasmin and tranexamic acid. These in vitro observations suggest a platelet localized activation of plasminogen, dependent on t-PA, enhanced by the presence of soluble fibrin. Since high concentrations of soluble fibrin and elevated levels of t-PA during CPB are observed, plasmin activity on the platelet surface during this period is anticipated. This plasmin activity reduces platelet metabolic functions and can be directed towards membrane glycoproteins such as glycoprotein Ib/IX complexes, thereby affecting hemostasis during and after CPB.

[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.

Effect of aspirin in coronary artery bypass grafting

OBJECTIVES

To evaluate the effect of aspirin (ASA) therapy on postoperative blood loss, transfusion requirements, reoperation for bleeding, duration of stay in the intensive care unit and in the hospital in a selected population undergoing a first coronary artery bypass grafting (CABG) surgery.

DESIGN

Prospective observational study in consecutive patients during a 3-month period.

SETTING

A teaching cardiothoracic center.

PARTICIPANTS

Two hundred forty consecutive patients undergoing elective coronary artery bypass grafting surgery for the first time.

INTERVENTIONS

Two hundred forty consecutive patients admitted for a first CABG the day before surgery were visited. patients with an abnormal routine coagulation screen or taking drugs that might have affected their coagulation mechanisms were prospectively excluded (n = 96). The date of the last dose of ASA was recorded in the 144 remaining patients, and data were acquired prospectively.

MEASUREMENTS AND MAIN RESULTS

Total mediastinal blood drainage, blood products usage, reopening, and duration of intensive care unit and hospital stay were recorded. Patients were grouped by days free of ASA. There were no significant differences detected between groups.

CONCLUSIONS

In patients undergoing a first CABG and with no known factors affecting their coagulation, ASA therapy did not appear to increase blood loss, reopening for bleeding, or blood products usage requirements during the hospital stay. ASA therapy did not influence the duration of stay in intensive care or in the hospital.

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

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Impact of transfusion of mediastinal shed blood on serum levels of cardiac enzymes

BACKGROUND

Infusion of shed mediastinal blood using an autotransfusion system is a widely applied technique of blood conservation in cardiac surgery. Serial determinations of serum creatine kinase (CK), its MB isoenzyme (CK-MB), and lactate hydrogenase (LDH) levels have been used to monitor perioperative myocardial injury. We investigated the impact of postoperative autotransfused blood infusion on serum levels of these enzymes.

METHODS

We performed a retrospective analysis of postoperative serum CK, CK-MB, and LDH levels of 300 patients who had elective uncomplicated aortocoronary bypass grafting. Shed mediastinal blood samples from 26 patients were analyzed for CK, CK-MB (enzymatic activity and mass), and LDH levels before infusion.

RESULTS

High postoperative serum levels of CK and LDH were observed after infusion of autotransfused blood. Shed mediastinal blood contained extremely high levels of these enzymes, particularly from patients who had internal mammary artery dissection. There was a strong correlation (r = 0.96) between measured CK-MB enzyme activities and those calculated from the CK-MB mass units.

CONCLUSIONS

Infusion of autotransfused blood containing high concentrations of CK and LDH results in elevated serum levels of these enzymes. Hemolysis, frequently present in shed blood, does not interfere with the routine biochemical assays for CK and CK-MB enzyme activities. Caution should be taken when postoperative cardiac enzyme levels are used to determine myocardial injury after aortocoronary bypass grafting if autotransfusion is used as a method of blood conservation.

Retransfusion of suctioned blood during cardiopulmonary bypass impairs hemostasis

In a previous study we observed extensive clotting and fibrinolysis in blood from the thoracic cavities during cardiopulmonary bypass. We hypothesized that retransfusion of this suctioned blood could impair hemostasis. In this prospective clinical study we investigated the effect of suctioned blood retransfusion on systemic blood activation and on postoperative hemostasis. During coronary artery bypass grafting in 40 patients, suctioned blood was collected separately. It then was retransfused to the patient at the end of the operation (n = 19), or it was retained (n = 21). During the study, 12 consecutive patients, randomized in two groups of 6, were analyzed for biochemical parameters indicating blood activation and clotting. The immediate and significant increase in circulating concentrations of thrombin-antithrombin III complex, tissue-type plasminogen activator, fibrin degradation products, and free plasma hemoglobin demonstrated the effect of suctioned blood retransfusion. Moreover, the increased concentrations of thrombin-antithrombin III complex and fibrin degradation products indicated renewed systemic clotting and fibrinolysis as a direct result of the retransfusion of suctioned blood. Concentrations of all indicators mentioned remained significantly lower in the retainment group. The clinical data showed that retainment of suctioned blood resulted in significantly decreased postoperative blood loss (822 mL in the retransfusion group versus 611 mL in the retainment group; p < 0.05) and similar or even reduced consumption of blood products (513 versus 414 mL red blood cell concentrate and 384 versus 150 mL single-donor plasma; both not significant). We conclude that retransfusion of highly activated suctioned blood during cardiopulmonary bypass exacerbates wound bleeding.

Autologous blood transfusion: evaluation of an alternative strategy in reducing exposure to allogeneic blood transfusion

The perceived risk of transfusion-transmitted disease led to the rejuvenation of autologous blood transfusion (ABT). ABT, a process in which the blood donor and recipient are the same, is increasingly becoming an integral component of the elective surgical protocol in many institutions. Various methods of ABT are being utilized. These include: preoperative blood donation, in which the patient donates blood prior to surgery and the blood is stored for an expected need during or after surgery; acute normovolemic hemodilution, in which blood is collected immediately prior to surgery and replaced with cell free fluids and then returned to the patient upon need; intraoperative blood salvage in which blood is collected from the surgical field and is reinfused after being washed and finally, postoperative blood salvage in which collected shed blood from surgical drains is reinfused to the patient. Although ABT is known to reduce the risk of allogeneic blood transfusion, it is not risk free and should be evaluated in relation to the patient's clinical picture. The combination of various methods of ABT in addition to the proper utilization of blood may consequently lead to the elimination of patients' exposure to allogeneic blood transfusion in many surgical procedures.