Cell salvage for minimising perioperative allogeneic blood transfusion

Transfusions and blood loss in total hip and knee arthroplasty: a prospective observational study

BACKGROUND

There is a high prevalence of blood product transfusions in orthopedic surgery. The reported prevalence of red blood cell transfusions in unselected patients undergoing hip or knee replacement varies between 21% and 70%. We determined current blood loss and transfusion prevalence in total hip and knee arthroplasty when tranexamic acid was used as a routine prophylaxis, and further investigated potential predictors for excessive blood loss and transfusion requirement.

METHODS/MATERIALS

In total, 193 consecutive patients undergoing unilateral hip (n = 114) or knee arthroplasty (n = 79) were included in a prospective observational study. Estimated perioperative blood loss was calculated and transfusions of allogeneic blood products registered and related to patient characteristics and perioperative variables.

RESULTS

Overall transfusion rate was 16% (18% in hip patients and 11% in knee patients, p = 0.19). Median estimated blood loss was significantly higher in hip patients (984 vs 789 mL, p < 0.001). Preoperative hemoglobin concentration was the only independent predictor of red blood cell transfusion in hip patients while low hemoglobin concentration, body mass index, and operation time were independent predictors for red blood cell transfusion in knee patients.

CONCLUSIONS

The prevalence of red blood cell transfusion was lower than previously reported in unselected total hip or knee arthroplasty patients. Routine use of tranexamic acid may have contributed. Low preoperative hemoglobin levels, low body mass index, and long operation increase the risk for red blood cell transfusion.

Cell salvage in emergency trauma surgery

BACKGROUND

Trauma is the leading cause of death in people under the age of 45 years. Over the past 20 years, intraoperative autologous transfusions (obtained by cell salvage, also known as intraoperative blood salvage (IBS)) have been used as an alternative to blood products from other individuals during surgery because of the risk of transfusion-related infections such as hepatitis and human immunodeficiency virus (HIV). In this review, we sought to assess the effects and cost of cell salvage in individuals undergoing abdominal or thoracic surgery.

OBJECTIVES

To compare the effect and cost of cell salvage with those of standard care in individuals undergoing abdominal or thoracic trauma surgery.

SEARCH METHODS

We ran the search on 25 November 2014. We searched the Cochrane Injuries Group's Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), Ovid MEDLINE, Ovid MEDLINE In-Process & Other Non-Indexed Citations, Ovid MEDLINE Daily and Ovid OLDMEDLINE, EMBASE Classic + EMBASE (OvidSP), PubMed, and ISI Web of Science (SCI-Expanded & CPSI-SSH). We also screened reference lists and contacted principal investigators.

SELECTION CRITERIA

Randomised controlled trials comparing cell salvage with no cell salvage (standard care) in individuals undergoing abdominal or thoracic trauma surgery.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data from the trial reports. We used the standard methodological procedures expected by The Cochrane Collaboration.

MAIN RESULTS

Only one small study (n = 44) fulfilled the inclusion criteria. Results suggested that cell salvage did not affect mortality overall (death rates were 67% (14/21 participants) in the cell salvage group and 65% (15/23) in the control group) (odds ratio (OR) 1.07, 95% confidence interval (CI) 0.31 to 3.72). For individuals with abdominal injury, mortality was also similar in both groups (OR 0.48, 95% CI 0.11 to 2.10).Less donor blood was needed for transfusion within the first 24 hours postinjury in the cell salvage group compared with the control group (mean difference (MD) -4.70 units, 95% CI -8.09 to -1.31). Adverse events, notably postoperative sepsis, did not differ between groups (OR 0.54, 95% CI 0.11 to 2.55). Cost did not notably differ between groups (MD -177.81, 95% CI -452.85 to 97.23, measured in GBP in 2002).

AUTHORS' CONCLUSIONS

Evidence for the use of cell salvage in individuals undergoing abdominal or thoracic trauma surgery remains equivocal. Large, multicentre, methodologically rigorous trials are needed to assess the relative efficacy, safety and cost-effectiveness of cell salvage in different surgical procedures in the emergency context.

Therapeutic options to minimize allogeneic blood transfusions and their adverse effects in cardiac surgery: a systematic review

INTRODUCTION

Allogeneic blood is an exhaustible therapeutic resource. New evidence indicates that blood consumption is excessive and that donations have decreased, resulting in reduced blood supplies worldwide. Blood transfusions are associated with increased morbidity and mortality, as well as higher hospital costs. This makes it necessary to seek out new treatment options. Such options exist but are still virtually unknown and are rarely utilized.

OBJECTIVE

To gather and describe in a systematic, objective, and practical way all clinical and surgical strategies as effective therapeutic options to minimize or avoid allogeneic blood transfusions and their adverse effects in surgical cardiac patients.

METHODS

A bibliographic search was conducted using the MeSH term "Blood Transfusion" and the terms "Cardiac Surgery" and "Blood Management." Studies with titles not directly related to this research or that did not contain information related to it in their abstracts as well as older studies reporting on the same strategies were not included.

RESULTS

Treating anemia and thrombocytopenia, suspending anticoagulants and antiplatelet agents, reducing routine phlebotomies, utilizing less traumatic surgical techniques with moderate hypothermia and hypotension, meticulous hemostasis, use of topical and systemic hemostatic agents, acute normovolemic hemodilution, cell salvage, anemia tolerance (supplementary oxygen and normothermia), as well as various other therapeutic options have proved to be effective strategies for reducing allogeneic blood transfusions.

CONCLUSION

There are a number of clinical and surgical strategies that can be used to optimize erythrocyte mass and coagulation status, minimize blood loss, and improve anemia tolerance. In order to decrease the consumption of blood components, diminish morbidity and mortality, and reduce hospital costs, these treatment strategies should be incorporated into medical practice worldwide.

The impact of blood management on length of stay after primary total knee arthroplasty

The current study investigates the impact of patient factors, surgical factors, and blood management on postoperative length of stay (LOS) in 516 patients who underwent primary total knee arthroplasty. Age, gender, type of anticoagulation, but not body mass index (BMI) were found to be highly significant predictors of an increased LOS. Allogeneic transfusion and the number of allogeneic units significantly increased LOS, whereas donation and/or transfusion of autologous blood did not. Hemoglobin levels preoperatively until 48 hours postoperatively were negatively correlated with LOS. After adjusting for confounding factors through Poisson regression, age (p = 0.001) and allogeneic blood transfusion (p = 0.002) were the most significant determinants of LOS. Avoiding allogeneic blood plays an essential role in reducing the overall length of stay after primary total knee arthroplasty.

De-implementation of expensive blood saving measures in hip and knee arthroplasties: study protocol for the LISBOA-II cluster randomized trial

Background

Despite evidence that erythropoietin and intra- and postoperative blood salvage are expensive techniques considered to be non-cost-effective in primary elective total hip and knee arthroplasties in the Netherlands, Dutch medical professionals use them frequently to prevent the need for allogeneic transfusion. To actually change physicians’ practice, a tailored strategy aimed at barriers that hinder physicians in abandoning the use of erythropoietin and perioperative blood salvage was systematically developed. The study aims to examine the effectiveness, feasibility and costs of this tailored de-implementation strategy compared to a control strategy.

Methods/Design

A cluster randomized controlled trial including an effect, process and economic evaluation will be conducted in a minimum of 20 Dutch hospitals. Randomisation takes place at hospital level. The hospitals in the intervention group will receive a tailored de-implementation strategy that consists of four components: interactive education, feedback in educational outreach visits, electronically sent reports on hospital performance (all aimed at orthopedic surgeons and anesthesiologists), and information letters or emails aimed at other involved professionals within the intervention hospital (transfusion committee, OR-personnel, pharmacists). The hospitals in the control group will receive a control strategy (i.e., passive dissemination of available evidence). Outcomes will be measured at patient level, using retrospective medical record review. This will be done in all hospitals at baseline and after completion of the intervention period. The primary outcome of the effect evaluation is the percentage of patients undergoing primary elective total hip or knee arthroplasty in which erythropoietin or perioperative blood salvage is applied. The actual exposure to the tailored strategy and users’ experiences will be assessed in the process evaluation. In the economic evaluation, the costs of the tailored strategy and the control strategy in relation to the difference in their effectiveness will be compared.

Discussion

This study will show whether a systematically developed tailored strategy is more effective for de-implementation of non-cost-effective blood saving measures than the control strategy. This knowledge can be used in national and international initiatives to make healthcare more efficient. It also provides more generalized knowledge regarding de-implementation strategies.

Trial registration

This trial is registered at the Dutch Trial Register NTR4044.

The efficacy and cost-effectiveness of cell saver use in instrumented posterior correction and fusion surgery for scoliosis in school-aged children and adolescents

Posterior spinal instrumentation and fusion surgery in school-aged children and adolescents is associated with the potential for massive intraoperative blood loss, which requires significant allogeneic blood transfusion. Until now, the intraoperative use of the cell saver has been extensively adopted; however, its efficacy and cost-effectiveness have not been well established. Therefore, the aim of this study is to determine the efficacy and cost-effectiveness of intraoperative cell saver use. This study was a single-center, retrospective study of 247 school-aged and adolescent patients who underwent posterior spinal instrumentation and fusion surgery between August 2007 and June 2013. A cell saver was used intraoperatively in 67 patients and was not used in 180 patients. Matched case-control pairs were selected using a propensity score to balance potential confounders in baseline characteristics. Allogeneic red blood cell (RBC) and plasma transfusions as well as blood transfusion costs were analyzed. The propensity score matching produced 60 matched pairs. Compared to the control group, the cell saver group had significantly fewer intraoperative allogeneic RBC transfusions (P = 0.012). However, when the combined postoperative and total perioperative periods were evaluated for the use of allogeneic RBC transfusion, no significant differences were observed between the two groups (P = 0.813 and P = 0.101, respectively). With regard to the total cost of perioperative transfusion of all blood products (RBC and plasma), costs for the control group were slightly lower than those of the cell saver group, but this variance did not reach statistical significance (P = 0.095). The use of the cell saver in posterior spinal instrumentation and fusion surgery in school-aged children and adolescents was able to decrease the amount of intraoperative allogeneic RBC transfusion but failed to decrease total perioperative allogeneic RBC transfusion. Moreover, the use of the cell saver was not cost-effective.

Intraoperative cell salvage in revision hip surgery

Allogenic blood is a finite resource, with associated risks. Previous studies show intraoperative cell salvage (ICS) can reduce allogenic transfusion rates in orthopaedic surgery. However, there are concerns regarding efficacy and cost-effectiveness of ICS. This study was carried out to review ICS use in revision hip arthroplasty. All patients who underwent ICS and re-infusion between 2008 and 2010 in the Southern General Hospital (SGH) were audited. The fall in haemoglobin (Hb), volume of blood re-infused and postoperative allogenic transfusion rates were recorded. This group was compared to a similar SGH cohort who underwent surgery by the same surgeons between 2006 and 2008, and a pre-2005 control group where no ICS was used. The proportion of patients receiving a postoperative allogenic transfusion fell by 55% in the 2008-2010 ICS cohort compared with the control, and by 40% compared with the previous ICS group. In both instances, there was a statistically significant (p < 0.001) reduction in mean units transfused per patient; in the 2008-2010 ICS cohort, a mean of 0.8 units was used per patient, while 1.4 were used in the 2006-2008 cohort. 3.5 units were used in the control group. There was no statistically significant difference in age or preoperative Hb between the groups, or in length of hospital stay. In this study, ICS has been shown to be effective in reducing rates and volume of postoperative allogenic transfusion in patients undergoing revision hip surgery at the SGH. However, further work is needed to establish the effect of changing anaesthetic technique on postoperative allogenic transfusion rates.

Favourable results of a new intraoperative and postoperative filtered autologous blood re-transfusion system in total hip arthroplasty: a randomised controlled trial

PURPOSE

A new intraoperative filtered salvaged blood re-transfusion system has been developed for primary total hip arthroplasty (THA) that filters and re-transfuses the blood that is lost during THA. This system is intended to increase postoperative haemoglobin (Hb) levels, reduce perioperative net blood loss and reduce the need for allogeneic transfusions. It supposedly does not have the disadvantages of intraoperative cell-washing/separating re-transfusion systems, such as extensive procedure, high costs and need for specialised personnel. To re-transfuse as much as blood as possible, postoperatively drained blood was also re-transfused.

METHODS

A randomised, controlled, blinded, single-centre trial was conducted in which 118 THA patients were randomised to an intraoperative autologous blood re-transfusion (ABT) filter system combined with a postoperative ABT filter unit or high-vacuum closed-suction drainage.

RESULTS

On average, 577 ml of blood was re-transfused in the ABT group: 323 ml collected intraoperatively and 254 ml collected postoperatively. Hb level was higher in the ABT vs the high-vacuum drainage group: 11.4 vs. 10.8 g/dl, p = 0.02 on day one (primary endpoint) and 11.0 vs. 10.4 g/dl, p = 0.007 on day three. Total blood loss was less in the autotransfusion group: 1472 vs. 1678 ml, p = 0.03. Allogeneic transfusions were needed in 3.6 % of patients in the ABT group and 6.5 % in the drainage group, p = 0.68.

CONCLUSION

The use of a new intraoperative ABT filter system combined with a postoperative ABT unit resulted in higher postoperative Hb levels and less total blood loss compared with a high-vacuum drain following THA.

Fibrin sealants or cell saver eliminate the need for autologous blood donation in anemic patients undergoing primary total knee arthroplasty

INTRODUCTION

Reducing allogeneic blood transfusions remains a challenge in total knee arthroplasty. Patients with preoperative anemia have a particularly high risk for perioperative blood transfusions.

MATERIALS AND METHODS

176 anemic patients (Hb < 13.5 g/dl) undergoing total knee replacement were prospectively evaluated to compare the effect of a perioperative cell saver (26 patients), intraoperative fibrin sealants (5 ml Evicel, Johnson & Johnson Wound Management, Ethicon, Somerville, NJ) (45 patients), preoperative autologous blood donation (PABD) (21 patients), the combination of fibrin sealants and preoperative autologous blood donation (44) and no intervention (40 patients) on perioperative blood loss and transfusion requirements.

RESULTS

All protocols resulted in significant reduction of allogeneic blood transfusions. Transfusion rates were similar with the use of PABD (19%), Evicel (18%), and cell saver (19%), all significantly lower than the control group (38 %, p < 0.05). Combining Evicel with PABD resulted in significantly higher wastage of autologous units (p < 0.05) with no significant reduction in allogeneic transfusion rate (14%). The use of fibrin sealant resulted in a significant reduction of blood loss compared to the PABD group (603 vs. 810 ml, p < 0.005) as well as the control group (603 vs. 822 ml, p < 0.005).

CONCLUSIONS

While PABD proved to be the most cost-effective treatment option in anemic patients, fibrin sealants and cell saver show similar reduction in allogeneic transfusion rates compared to controls. The combination of fibrin sealants and PABD is not cost-effective and increases the number of wasted units.

Frequent use of blood-saving measures in elective orthopaedic surgery: a 2012 Dutch blood management survey

Background

Blood loss in hip and knee arthroplasties may necessitate allogeneic blood transfusions. Different blood-saving measures (BSMs) were introduced to reduce these transfusions. Purpose of the present study was to assess the frequency of BSM use, stratified by type and hospital setting of orthopaedic departments in the Netherlands.

Methods

An internet-based questionnaire was sent to all heads of orthopaedic departments of Dutch hospitals and private clinics (n = 99). Questions were asked on how often BSMs were used, reported on a 5-point Likert scale (never, almost never, regularly, almost always, always). In addition there were questions about discontinuation of anticoagulants preoperatively, the number of annually performed arthroplasties (size) and hospital setting.

Results

The survey was completed by 81 (82%) departments. BSMs used frequently (regularly, almost always, always) were erythropoietine (EPO), with 55 (68%) departments being frequent users; acute normovolemic hemodilution, used frequently in 26 (32%) departments; cell saver in 25 (31%) and postoperative drainage and re-infusion in 56 (69%) departments. When compared by size, frequent EPO use was more common in large departments (with 22 (88%) large departments being frequent users versus 13 (63%) small departments and 16 (55%) intermediate departments, p = 0.03). No differences by size or type were observed for other BSMs.

Conclusions

Compared with previous survey’s there is a tremendous increase in use of BSMs. EPO and autologous blood salvage techniques are the most often used modalities. Costs might be saved if use of non-cost-effective BSMs is stopped.

Clinical efficacy and cost effectiveness of intraoperative cell salvage in pelvic trauma surgery

INTRODUCTION

Pelvic acetabular injuries are associated with significant blood loss. This is compounded by multiple surgical interventions including definitive fracture fixation, which put patients at further risk of postoperative transfusion. We use intraoperative cell salvage routinely as a blood conservation strategy to address this issue. This is a prospective evaluation of the clinical efficacy and cost effectiveness of using intraoperative cell salvage in patients with pelvic acetabular injuries.

METHODS

Data were collected prospectively for all the patients who underwent pelvic acetabular fracture fixation at our institution. A total of 30 patients (25 men, 5 women) with a mean age of 41 years (range: 31-79 years) were assessed over a period of 10 months.

RESULTS

The mean preoperative and postoperative haemoglobin levels were 11.8g/dl and 9.9g/dl respectively. The mean intraoperative blood loss was 1,232.5ml (range: 150-2,693ml). The mean amount of blood salvaged and retransfused through a cell saver was 388ml. Of the 30 patients, 14 (47%) required transfusion after surgery and 26 units of blood were transfused. In terms of cost effectiveness, a total of £2,572 in 30 patients or £86 per patient were saved.

CONCLUSIONS

We found intraoperative cell salvage to be clinically efficacious and cost effective in patients with pelvic acetabular injuries.

Ranking the effectiveness of autologous blood conservation measures through validated modeling of independent clinical data

BACKGROUND

Future supply with allogeneic blood transfusions faces several crucial challenges that warrant thorough (re-)evaluation of existing alternatives. Meta-analyses have indicated a significant potential for autologous blood conservation (ABC) measures to reduce the need for allogeneic blood transfusions. The quality of currently available studies, however, prohibits definite conclusions. Under these circumstances, mathematical modeling offers unique opportunities to compare various ABC measures and to test the impact of different variables on efficacy and effectiveness.

STUDY DESIGN AND METHODS

We performed an extensive search for clinical ABC studies, focusing on acute normovolemic hemodilution (ANH), intraoperative blood salvage (IBS), or preoperative autologous deposit (PAD). Only ABC studies providing a minimum set of clinical variables were included. Using a clinically validated mathematical model, we then calculated maximal allowable blood loss (efficacy) and increase in red blood cell (RBC) mass (effectiveness) to rank the three techniques.

RESULTS

We identified 21 clinical ABC studies, including 3926 patients, as suitable for our model. Our model shows that IBS with high recovery rates is the most efficacious and effective ABC measure. PAD will reveal nearly similar efficacy and effectiveness, only if sufficient time for RBC regeneration has passed and if 4 PAD units or more are available. Our model further demonstrates that ANH as well as IBS with low recovery rates are the least efficacious and effective alternatives.

CONCLUSIONS

IBS appears to be the most efficacious and effective ABC measure. PAD can only reduce the need for allogeneic blood transfusions under certain circumstances. ANH does not appear to play an important role in ABC.

Blood management and transfusion strategies in 600 patients undergoing total joint arthroplasty: an analysis of pre-operative autologous blood donation

BACKGROUND

Blood loss during total joint arthroplasty strongly influences the time to recover after surgery and the quality of the recovery. Blood conservation strategies such as pre-operative autologous blood donation and post-operative cell salvage are intended to avoid allogeneic blood transfusions and their associated risks. Although widely investigated, the real effectiveness of these alternative transfusion practices remains controversial.

MATERIALS AND METHODS

The surgery reports of 600 patients undergoing total joint arthroplasty (312 hip and 288 knee replacements) were retrospectively reviewed to assess transfusion needs and related blood management at our institute. Evaluation parameters included post-operative blood loss, haemoglobin concentration measured at different time points, ASA score, and blood transfusion strategies.

RESULTS

Autologous blood donation increased the odds of receiving a red blood cell transfusion. Reinfusion by a cell salvage system of post-operative shed blood was found to limit adverse effects in cases of severe post-operative blood loss. The peri-operative net decrease in haemoglobin concentration was higher in patients who had predeposited autologous blood than in those who had not.

DISCUSSION

The strengths of this study are the high number of cases and the standardised procedures, all operations having been performed by a single orthopaedic surgeon and a single anaesthesiologist. Our data suggest that a pre-operative autologous donation programme may often be useless, if not harmful. Conversely, the use of a cell salvage system may be effective in reducing the impact of blood transfusion on a patient's physiological status. Basal haemoglobin concentration emerged as a useful indicator of transfusion probability in total joint replacement procedures.

Exploring the use of expanded erythroid cells for autologous transfusion for anemia of prematurity

BACKGROUND

Autologous cord blood (CB) red blood cells (RBCs) can partly substitute transfusion needs in premature infants suffering from anemia. To explore whether expanded CB cells could provide additional autologous cells suitable for transfusion, we set up a simple one-step protocol to expand premature CB cells.

STUDY DESIGN AND METHODS

CB buffy coat cells and isolated CD34-positive (CD34(pos) ) cells from premature and full-term CB and adult blood were tested with several combinations of growth factors while omitting xenogeneic proteins from the culture medium. Cell differentiation was analyzed serially during 21 days using flow cytometry, progenitor assays, and high-performance liquid chromatography.

RESULTS

Expanded CB buffy coat cells resulted in a threefold higher number of erythroblasts than the isolated CD34(pos) cells. However, the RBCs contaminating the buffy coat remained present during the culture with uncertain quality. Premature and full-term CB CD34(pos) cells had similar fold expansion capacity and erythroid differentiation. With the use of interleukin-3, stem cell factor, and erythropoietin, the fold increases of all CD34(pos) cell sources were similar: CB 3942 ± 1554, adult peripheral mobilized blood 4702 ± 1826, and bone marrow (BM) 4143 ± 1908. The proportion of CD235a expression indicating erythroblast presence on Day 21 was slightly higher in the adult CD34(pos) cell sources: peripheral blood stem cells (96.7 ± 0.8%) and BM (98.9 ± 0.5%) compared to CB (87.7 ± 2.7%; p = 0.002). We were not able to induce further erythroid maturation in vitro.

CONCLUSION

This explorative study showed that fairly pure autologous erythroid-expanded cell populations could be obtained by a simple culture method, which should be optimized. Future challenges comprise obtaining ex vivo enucleation of RBCs with the use of a minimal manipulating approach, which can add up to autologous RBCs derived from CB in the treatment of anemia of prematurity.

Washing and filtering of cell-salvaged blood - does it make autotransfusion safer?

Autologous transfusion was first performed in the late 1800s, but it was not until the 1970s that devices were developed that enabled widespread adoption of the practice. Unwashed salvaged blood contains thrombogenic products, cell breakdown products and plasma proteins, and gross chemical, cellular and physical contaminants. Washing and filtering of salvaged blood is routinely performed to remove or reduce these elements. In this paper we review the clinical data supporting the need for washing and filtering of salvaged blood.

Transfusion thresholds and other strategies for guiding allogeneic red blood cell transfusion

BACKGROUND

Most clinical practice guidelines recommend restrictive red cell transfusion practices, with the goal of minimising exposure to allogeneic blood. The purpose of this review is to compare clinical outcomes in patients randomised to restrictive versus liberal transfusion thresholds (triggers).

OBJECTIVES

To examine the evidence for the effect of transfusion thresholds on the use of allogeneic and/or autologous red cell transfusion, and the evidence for any effect on clinical outcomes.

SEARCH METHODS

We identified trials by searching; The Cochrane Injuries Group Specialised Register (searched 01 Feb 2011), Cochrane Central Register of Controlled Trials 2011, issue 1 (The Cochrane Library), MEDLINE (Ovid) 1948 to January Week 3 2011, EMBASE (Ovid) 1980 to 2011 (Week 04), ISI Web of Science: Science Citation Index Expanded (1970 to Feb 2011), ISI Web of Science: Conference Proceedings Citation Index- Science (1990 to Feb 2011). We checked reference lists of other published reviews and relevant papers to identify any additional trials.

SELECTION CRITERIA

Controlled trials in which patients were randomised to an intervention group or to a control group. Trials were included where intervention groups were assigned on the basis of a clear transfusion 'trigger', described as a haemoglobin (Hb) or haematocrit (Hct) level below which a red blood cell (RBC) transfusion was to be administered.

DATA COLLECTION AND ANALYSIS

Risk ratios of requiring allogeneic blood transfusion, transfused blood volumes and other clinical outcomes were pooled across trials, using a random effects model. Data extraction and assessment of the risk of bias was performed by two people.

MAIN RESULTS

Nineteen trials involving a total of 6264 patients were identified, and were similar enough that the results could be combined. Restrictive transfusion strategies reduced the risk of receiving a RBC transfusion by 39% (RR 0.61, 95% CI 0.52 to 0.72). This equates to an average absolute risk reduction (ARR) of 34% (95% CI 24% to 45%). The volume of RBCs transfused was reduced on average by 1.19 units (95% CI 0.53 to 1.85 units). However, heterogeneity between trials was statistically significant (P<0.00001; I(2)≥93%) for these outcomes. Restrictive transfusion strategies did not appear to impact the rate of adverse events compared to liberal transfusion strategies (i.e. mortality, cardiac events, myocardial infarction, stroke, pneumonia and thromboembolism). Restrictive transfusion strategies were associated with a statistically significant reduction in hospital mortality (RR 0.77, 95% CI 0.62-0.95) but not 30 day mortality (RR 0.85, 95% CI 0.70 to 1.03). The use of restrictive transfusion strategies did not reduce functional recovery, hospital or intensive care length of stay. The majority of patients randomised were included in good quality trials, but some items of methodological quality were unclear. There are no trials in patients with acute coronary syndrome.

AUTHORS' CONCLUSIONS

The existing evidence supports the use of restrictive transfusion triggers in most patients including those with pre-existing cardiovascular disease. As there are no trials, the effects of restrictive transfusion triggers in high risk groups such as acute coronary syndrome need to be tested in further large clinical trials. In countries with inadequate screening of donor blood, the data may constitute a stronger basis for avoiding transfusion with allogeneic red cells.

Cell salvage is beneficial for all cardiac surgical patients: arguments for and against

Extensive literature has been published evaluating the use of cell salvage in cardiac surgery. However, the most recently published blood management guidelines do not give unequivocal direction on the use of cell salvage in cardiac surgical procedures and neither do recent meta-analyses and randomized controlled trials. In part, this reflects variation in the details of how cell salvage is used, including the specific equipment chosen. Consensus on the optimal approach to cell salvage would be helpful. A well-designed, appropriately powered, multicenter study could then be carried out with one or more specified devices to evaluate the efficacy of this agreed approach to cell salvage in the cardiac surgical environment.