Plateletpheresis before redo CABG diminishes excessive blood transfusion

The effect of pre-operative blood withdrawal, with or without sequestration, on allogeneic blood product requirements

A common effect of autologous blood withdrawal before cardiopulmonary bypass (CPB) is a decrease in haematocrit (Hct) and haemoglobin (Hb) content. A refinement of this technique is autologous blood withdrawal with the sequestration of platelet rich plasma (PRP) and red blood cells (RBCs).

METHODS

One hundred and four patients were included in a randomized study stratified into three groups: the autologous blood withdrawal group (Group 1), the autologous blood withdrawal group with blood loss sequestration (Group 2) and the control group (Control group). In Group 1, the amount of withdrawn blood was transfused after CPB. In Group 2, the RBCs were transfused immediately after sequestration and the PRP was transfused after the termination of CPB. In the Control group, no autologous blood withdrawal was employed. The following variables were analysed: blood loss, blood products transfusion, fluid transfusion, diuresis, haematological and coagulation data and the duration of the operation and intensive care unit stay.

RESULTS

We found no significant differences in peri-operative blood loss and transfused blood products among the three groups. There was a trend towards a lower amount of transfused fresh frozen plasma (FFP) for Group 1 (p =0.057) in the operation room (OR). The use of plasma expanders post-CPB was significantly higher in the Control group (p=0.024). RBCs coming from the auto-transfusion device were, for Group 1, significantly lower (p=0.007). The Hb and Hct values in Group 1, at start and end of CPB, were significantly lower (p=0.023-0.003 / 0.001-0.001, respectively). All other parameters were not significantly different.

CONCLUSION

there were no significant differences between the study groups. This randomized trial shows that, although sequestration immediately after autologous blood withdrawal has no added value, autologous blood withdrawal in patients with a normal pre-operative Hb and Hct is simple, inexpensive and allows for autologous blood transfusion.

Platelet function in stored heparinised autologous blood is not superior to in patient platelet function during routine cardiopulmonary bypass

Background

In cardiac surgery, cardiopulmonary bypass (CPB) and unfractionated heparin have negative effects on blood platelet function. In acute normovolemic haemodilution autologous unfractionated heparinised blood is stored ex-vivo and retransfused at the end of the procedure to reduce (allogeneic) transfusion requirements. In this observational study we assessed whether platelet function is better preserved in ex vivo stored autologous blood compared to platelet function in the patient during CPB.

Methodology/Principal Finding

We measured platelet aggregation responses pre-CPB, 5 min after the start of CPB, at the end of CPB, and after unfractionated heparin reversal, using multiple electrode aggregometry (Multiplate®) with adenosine diphosphate (ADP), thrombin receptor activating peptide (TRAP) and ristocetin activated test cells. We compared blood samples taken from the patient with samples taken from 100 ml ex-vivo stored blood, which we took to mimick blood storage during normovolemic haemodilution. Platelet function declined both in ex-vivo stored blood as well as in blood taken from the patient. At the end of CPB there were no differences in platelet aggregation responses between samples from the ex vivo stored blood and the patient.

Conclusion/Significance

Ex vivo preservation of autologous blood in unfractionated heparin does not seem to be profitable to preserve platelet function.

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.

Platelet-rich-plasmapheresis for minimising peri-operative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood have generated considerable enthusiasm for the use of technologies intended to reduce the use of allogeneic blood (blood from an unrelated donor). Platelet-rich plasmapheresis (PRP) offers an alternative approach to blood conservation.

OBJECTIVES

To examine the evidence for the efficacy of PRP in reducing peri-operative allogeneic red blood cell (RBC) transfusion, and the evidence for any effect on clinical outcomes such as mortality and re-operation rates.

SEARCH STRATEGY

We identified studies by searching MEDLINE (1950 to 2009), EMBASE (1980 to 2009), The Cochrane Library (Issue 1, 2009), the Internet (to March 2009) and the reference lists of published articles, reports, and reviews.

SELECTION CRITERIA

Controlled parallel group trials in which adult patients, scheduled for non-urgent surgery, were randomised to PRP, or to a control group which did not receive the intervention.

DATA COLLECTION AND ANALYSIS

Primary outcomes measured were: the number of patients exposed to allogeneic RBC transfusion, and the amount of RBC transfused. Other outcomes measured were: the number of patients exposed to allogeneic platelet transfusions, fresh frozen plasma, and cryoprecipitate, blood loss, re-operation for bleeding, post-operative complications (thrombosis), mortality, and length of hospital stay. Treatment effects were pooled using a random-effects model. Trial quality was assessed using criteria proposed by Schulz et al (Schulz 1995).

MAIN RESULTS

Twenty-two trials of PRP were identified that reported data for the number of patients exposed to allogeneic RBC transfusion. These trials evaluated a total of 1589 patients. The relative risk (RR) of exposure to allogeneic blood transfusion in those patients randomised to PRP was 0.73 (95%CI 0.59 to 0.90), equating to a relative risk reduction (RRR) of 27% and a risk difference (RD) of 19% (95%CI 10% to 29%). However, significant heterogeneity of treatment effect was observed (p < 0.00001; I² = 79%). When the four trials by Boldt are excluded, the RR is 0.76 (95% CI 0.62 to 0.93). On average, PRP did not significantly reduce the total volume of RBC transfused (weighted mean difference [WMD] -0.69, 95%CI -1.93 to 0.56 units). Trials provided inadequate data regarding the impact of PRP on morbidity, mortality, and hospital length of stay. Trials were generally small and of poor methodological quality.

AUTHORS' CONCLUSIONS

Although the results suggest that PRP is effective in reducing allogeneic RBC transfusion in adult patients undergoing elective surgery, there was considerable heterogeneity of treatment effects and the trials were of poor methodological quality. The available studies provided inadequate data for firm conclusions to be drawn regarding the impact of PRP on clinically important endpoints.

Platelet-rich-plasmapheresis for minimising peri-operative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood have generated considerable enthusiasm for the use of technologies intended to reduce the use of allogeneic blood (blood from an unrelated donor). Platelet-rich plasmapheresis (PRP) offers an alternative approach to blood conservation.

OBJECTIVES

To examine the evidence for the efficacy of PRP in reducing peri-operative allogeneic red blood cell (RBC) transfusion, and the evidence for any effect on clinical outcomes such as mortality and re-operation rates.

SEARCH STRATEGY

Studies were identified by: computer searches of MEDLINE, EMBASE, Current Contents, and the Cochrane Library (to June 2001). These searches were supplemented by checking the reference lists of published articles, reports, and reviews.

SELECTION CRITERIA

Controlled parallel group trials in which adult patients, scheduled for non-urgent surgery, were randomised to PRP, or to a control group who did not receive the intervention.

DATA COLLECTION AND ANALYSIS

Main outcomes measured were: the number of patients receiving an allogeneic RBC transfusion, and the amount of RBC transfused. Trial quality was assessed using criteria proposed by Schulz et al. (Schulz 1995) and Jadad et al. (Jadad 1996).

MAIN RESULTS

Nineteen trials of PRP were identified that reported data for the number of patients exposed to allogeneic RBC transfusion. These trials evaluated a total of 1452 patients. The pooled relative risk (RR) of exposure to allogeneic blood transfusion in those patients randomised to PRP was 0.71 (95%CI: 0.56, 0.90), equating to a relative risk reduction (RRR) of 29%; the average absolute risk reduction (ARR) was 19% (RD = -0.19: 95%CI: -0.29, -0.09). On average, PRP did not significantly reduce the total volume of RBC transfused (weighted mean difference [WMD] = -0.69: 95%CI: -1.93, 0.56 units). Substantial statistical heterogeneity was observed (p < 0.001). Trials provided inadequate data regarding the impact of PRP on morbidity, mortality, and hospital length of stay. The majority of trials were small and of poor methodological quality.

REVIEWER'S CONCLUSIONS

Although the results suggest that PRP is effective in reducing allogeneic RBC transfusion in adult patients undergoing elective surgery, there was considerable heterogeneity in treatment effects and the trials were of poor methodological quality. As the majority of trials were unblinded, transfusion practices may have been influenced by knowledge of the patient's allocation status, potentially exaggerating the true magnitude of the beneficial effect of PRP. The available studies provided inadequate data for firm conclusions to be drawn regarding the impact of PRP on clinically important endpoints.

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.

Platelet pheresis is not a useful adjunct to blood-sparing strategies in cardiac surgery

OBJECTIVE

To examine whether specific platelet pheresis (minimal plasma harvested) would contribute toward reduced blood loss and allogenic blood requirements after cardiac surgery.

DESIGN

A prospective randomized trial.

SETTING

A large cardiothoracic surgical center.

PARTICIPANTS

Consenting patients undergoing routine coronary artery or valve surgery (n = 54).

INTERVENTIONS

Patients in the pheresis group underwent platelet pheresis in the anesthetic preparation room before general anesthesia. Pheresed platelets were stored during cardiopulmonary bypass and were returned to the patients after reversal of heparin with protamine toward the end of surgery. Control patients underwent their operations without this intervention.

MEASUREMENTS AND MAIN RESULTS

Primary endpoints were blood loss and transfusion requirements. There were no differences between the 2 groups (pheresis v control: median loss, 960 mL v 1100 mL, p = 0.15; median blood transfused, 896 mL v 635 mL, p = 0.71). Secondary endpoints included analysis of platelet counts, platelet function, and surface markers. Counts remained the same after retransfusion of platelets up to 2 hours after surgery. Platelet aggregation to ristocetin was well preserved, but adenosine diphosphate caused almost no aggregation of the harvested platelets. Flow cytometry revealed the platelets to have a reduced surface density of the glycoprotein 1b receptor, and 13% of them were irreversibly activated.

CONCLUSION

Platelet pheresis activates a proportion of the harvested platelets and impairs the function of the remainder; this may explain its failure to reduce postoperative blood loss and transfusion requirements.

The effects of platelet apheresis in total hip replacement surgery on platelet activation

BACKGROUND

Autologous platelet rich plasma (PRP) harvest with autotransfusion devices has been used for 10 years in cardiac surgery and recently in orthopedics as a blood saving method. The quality of the harvested platelets has not been adequately examined, in part because of methodological difficulties in studying platelet function during surgery.

METHODS

Twenty patients undergoing primary total hip replacement (THR) were studied. Ten patients underwent an immediate preoperative platelet apheresis to obtain concentrated platelet rich plasma (c-PRP). The other 10 patients not undergoing apheresis were allocated to a control group. Platelet activation was evaluated as the population expressing P-selectin on the surface of platelets in the c-PRP and in blood samples collected pre-, per- and postoperatively. The method used was flow cytometry.

RESULTS AND CONCLUSIONS

A minor population of activated platelets was found to be circulating in the patients' blood, with a highly significant difference between patients (P = 0.005), and with a range of 1-23% in peroperative activation. PRP harvest did not significantly alter platelet activity. The platelet apheresis procedure did not inhibit platelet function in the c-PRP, as judged by a high proportion of platelets that could be activated in ADP stimulation experiments (mean value +/- SD 86% +/- 7.5%).

Hemostatic Abnormalities in Cardiopulmonary Bypass: Pathophysiologic and Transfusion Considerations

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

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

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

Augmented autologous transfusions in major reconstructive spine surgery

Intraoperative autologous transfusion during major reconstructive spine surgery decreased allogeneic red blood cell transfusions, but patients were exposed to significant numbers of allogeneic blood products. This study reports a prospective study of 160 randomized patients undergoing major reconstructive spine surgery. Without delaying start of surgery, 80 patients underwent hemapheresis with coincidental normovolemic hemodilution in the operating room to sequester autologous blood components. A therapeutic dose plateletpheresis product and an average of 2 U each of freshly collected autologous red cells and fresh plasma were prepared prior to surgical incision. The same supplies and equipment were used subsequently to carry out intraoperative autologous transfusion (IAT). Autologous plasma and platelets were transfused to Sequestration patients, contributing to a significant decrease of total allogeneic donor exposures. One or more autologous red blood cell unit equivalents were cost effectively salvaged and retransfused to 78% of the Sequestration patients. Altogether, autologous red cells comprised 87% of the total red cells transfused. During the same time period, 80 age-, sex-, and weight-matched controls, who received IAT only, were accrued for comparison with Sequestration patients. Of all red cells transfused to control patients, autologous units comprised 47%. Both patient groups received the same total perioperative red blood cell support. The per patient cost for IAT, with or without sequestration, was competitive with supplying one unit of cross-matched allogeneic red cells. IAT only patients had greater allogeneic blood donor exposures than Sequestration patients, in whom the numbers of allogeneic red cells, plasma and platelet transfusions were decreased. Compared with IAT alone, the hospital post-operative stay of Sequestration patients was 23% less than IAT only patients.

Platelet-rich plasma sequestration, with therapeutic platelet yields, reduces allogeneic transfusion in complex cardiac surgery

Platelet dysfunction is the most common cause of nonsurgical bleeding after cardiopulmonary bypass (CPB). We hypothesized that reinfusion of a therapeutic quantity of platelets sequestered before CPB would decrease the need for allogeneic platelet transfusion, as well as decrease bleeding and total allogeneic transfusion, in cardiac surgery patients at moderately high risk for bleeding. Fifty-five patients undergoing either reoperative coronary artery bypass (CABG) or combined CABG and valve replacement were randomized to control or platelet-rich plasma sequestration (pheresis) groups. All patients received intraoperative epsilon-aminocaproic acid infusions. There was no significant difference between groups with respect to preoperative characteristics, duration of CPB, or target postoperative hematocrit. Mean platelet yields were 6.2 +/- 2.1 units (3.1 x 10(11) platelets). Mean pheresis time was 44 min. Allogeneic platelets (range = 6-12 units) were transfused to 28% of control patients, compared with 0% of pheresis patients (P < 0.01). Allogeneic packed red blood cells were transfused to 45% of control patients (1.2 units per patient) versus 31% of pheresis patients (0. 7 unit per patient) (P = 0.35). Total allogeneic units transfused were significantly reduced in the pheresis group (P < 0.02). Mediastinal chest tube drainage was not significantly decreased in the pheresis group. In this prospective, randomized study, therapeutic platelet yields were obtained before CPB. In contrast with recent studies with low platelet yields, these data support the conclusion that platelet-rich plasma sequestration is effective in reducing allogeneic platelet transfusions and total allogeneic units transfused in cardiac surgery patients at moderately high risk for post-CPB coagulopathy and bleeding.

IMPLICATIONS

Transfusion of allogeneic blood products, including platelets, is common during complex cardiac surgical procedures. In the present prospective, randomized study, a significant reduction in allogeneic platelet transfusion and total allogeneic units transfused was observed after the reinfusion of a therapeutic quantity of autologous platelets sequestered before cardiopulmonary bypass.

The platelet in cardiopulmonary bypass

Platelets are the smallest of the blood cells and are known to be activated during cardiopulmonary bypass. They play a role in many associated complications. Both quantitative and qualitative platelet defects have been demonstrated, resulting in microvascular hemorrhage and thromboembolism. As their interactions with endothelium and other blood cells are unraveled, the important contribution they make toward the systemic inflammatory response to operation seen in cardiopulmonary bypass is increasingly evident. In this review, we consider platelet activation during cardiopulmonary bypass, the resultant clinical effects, and potential approaches to therapy and prevention.

Platelet-rich plasmapheresis in cardiac surgery: a meta-analysis of the effect on transfusion requirements

OBJECTIVE

Our purpose was to determine whether intraoperative platelet-rich plasmapheresis in cardiac surgery is effective in reducing the proportion of patients exposed to allogeneic red cell transfusions.

METHODS

A systematic search for prospective, randomized trials of platelet-rich plasmapheresis in cardiac surgery, using MEDLINE, HEALTHSTAR, Current Contents, "Biological Abstracts," and EMBASE/Excerpta Medica up to August 1997, was completed. Trials were included if they reported either the proportion of patients exposed to allogeneic red cells or the units of allogeneic red cells transfused. Trials were abstracted by 2 independent investigators and the quality of trial design was assessed with the use of a validated scale.

RESULTS

Seventeen references met the inclusion criteria (1369 patients [675 control: 694 platelet-rich plasmapheresis]). Platelet-rich plasmapheresis reduced the likelihood of exposure to allogeneic red cells in cardiac surgery (odds ratio 0.44; 95% confidence interval 0.27, 0.72, P = .001). Platelet-rich plasmapheresis had a small but statistically significant effect on both the volume of blood lost in the first 24 hours (weighted mean difference -102 mL; 95% confidence interval -148, -55 mL, P < .0001) and the mean units transfused (weighted mean difference -0.33 units; 95% confidence interval -0.43, -0.23, P < .0001). However, platelet-rich plasmapheresis was only marginally effective (odds ratio 0.83, 95% confidence interval 0.34, 2.01, P = .68) for "good" quality trials, whereas it appeared very effective in trials with poor methodologic quality (odds ratio 0.33, 95% confidence interval 0.17, 0.62, P = .0007).

CONCLUSIONS

Although platelet-rich plasmapheresis appeared effective in decreasing the proportion of patients receiving transfusions after cardiac operations, the quality of most of the supporting trials was low and the benefit was small in trials of good quality. Further clinical trials should be completed.

Acute normovolemic red cell exchange for cardiopulmonary bypass in sickle cell disease

A patient with sickle cell disease (hematocrit, 28.5%; hemoglobin S fraction, 79%), required mitral valve repair. Partial red cell removal and blood component sequestration with an autotransfusion device before cardiopulmonary bypass initially decreased the sickle red cell mass. This was followed by an acute one-volume whole blood exchange transfusion performed upon the initiation of cardiopulmonary bypass, resulting in a further reduction. Both techniques yielded fresh autologous plasma for use; sequestration yielded a platelet-pheresis product. Adequate postbypass hemostasis was demonstrated.