Washing of banked blood by three different blood salvage devices

Application of an autotransfusion pressure control system in blood salvage

OBJECTIVE

This study was performed to evaluate the effect of a homemade autotransfusion pressure-control system on the regulation of negative pressure and to clarify the influence of different negative pressures on the recovered erythrocytes.

METHODS

Fifty patients were randomly divided into five groups, and five different suction-generated negative pressures were applied. Before suction, 6 mL of blood was collected from the surgical field; after suction, 6 mL of blood was collected from the blood storage tank. The hemoglobin, hematocrit, mean corpuscular volume, newly generated standardized plasma free hemoglobin, and change in the hemolysis rate of erythrocytes before and after suction were compared. Additionally, the erythrocyte morphology was observed.

RESULTS

The hemoglobin and hematocrit were significantly different before and after suction in all five groups. As the suction pressure increased, gradual increases were noted in the number of abnormal erythrocytes in the field of view, the newly generated standardized plasma free hemoglobin, and the change in the hemolysis rate.

CONCLUSIONS

The destruction rate of erythrocytes increased as the suction-generated negative pressure increased. When using a pressure-control system, a negative pressure of <200 mmHg should be applied to reduce the damage to the autotransfused blood.

Does donor sex influence the potential for transfusion with washed packed red blood cells to limit transfusion-related immune responses in preterm newborns?

OBJECTIVE

To evaluate the association of donor sex with transfusion-associated recipient immune responses in preterm newborns receiving unwashed and washed blood.

DESIGN

A cohort study using data collected during the Effect of Washed versus Unwashed Packed Red Blood Cell Transfusion on Immune Responses in the Extremely Preterm Newborn randomised trial.

SETTING

Participants were recruited from two South Australian hospitals between September 2015 and December 2020.

PATIENTS

Preterm newborns (<29 weeks).

INTERVENTIONS

Transfusion with unwashed and washed packed red blood cells (PRBCs) from either exclusively male or any female donor for the first three transfusions.

MAIN OUTCOMES MEASURES

The primary outcome was the change from baseline in post-transfusion plasma cytokine concentrations, specifically interferon gamma, interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-12, IL-17A and tumour necrosis factor (TNF).

RESULTS

In total, 153 newborns were evaluated. By the third transfusion, the magnitude of pretransfusion to post-transfusion change in cytokines between the groups differed for IL-6 (p=0.003), IL-12 (p=0.008), IL-17A (p=0.003) and TNF (p=0.007). On post hoc comparison, compared with the unwashed-any female donor group, IL-6 (p<0.05), IL-12 (p<0.05) and IL-17A (p<0.01) were lower in the washed-exclusively male donor group, and IL-6 (p<0.01), IL-12 (p<0.05) and TNF (p<0.01) were lower in the washed-any female donor group.

CONCLUSION

These findings suggest that transfusion with unwashed PRBCs from female donors is associated with an increased recipient immune response, an effect that can be ameliorated with pretransfusion washing. Larger randomised controlled studies confirming this mechanistic link between donor sex and transfusion-associated morbidity are warranted.

TRIAL REGISTRATION NUMBER

ACTRN12613000237785.

Acid citrate dextrose formula A versus unfractionated heparin for anticoagulation of salvaged red blood cells in cardiac surgery

Red blood cell salvage plays an important role in reducing the use of allogeneic blood transfusion during cardiac surgery. While there is consensus as to the benefit of employing cell salvage systems, there are no clear recommendations on the anticoagulant used for salvaged blood. In eight patients undergoing elective cardiac surgery at our university hospital's cardiovascular center, the authors describe hemodynamic effects of salvaged autologous blood transfusion when either unfractionated heparin or acid citrate dextrose formula A was used as the anticoagulant. Mean arterial pressure, heart rate, central venous pressure and acid-base status of the autologous red blood cell concentrate were compared between patients receiving autologous blood anticoagulated with acid citrate dextrose formula A versus unfractionated heparin. A clinically relevant decrease in mean arterial pressure (median change, - 19 mmHg [min -29; max -1] and marked acidosis [group median <6.30 [<6.30; 6.49] was observed in group acid citrate dextrose formula A. Acid citrate dextrose formula A anticoagulant for autologous red blood cell salvage has the potential to cause major adverse hemodynamic events during free-flowing re-transfusion of autologous red blood cell concentrate. Acute ionized hypocalcemia and acidemia may ensue from residual citrate in the supernatant of red blood cell concentrate reconstituted in unbuffered saline.

Spectrum Medical Quantum or Terumo CDI 500: Which Device Measures Hemoglobin and Oxygen Saturation Most Accurately When Compared to a Benchtop Blood Analyzer?

To examine the accuracy between analyzers, the Terumo CDI 500 and the Spectrum Medical Quantum were compared to each other and to the ABL90 FLEX benchtop blood analyzer. Patients were retrospectively identified who underwent cardiac surgery requiring cardiopulmonary bypass between August 1, 2018 and November 1, 2019. Hemoglobin and venous saturation (SvO2) values from all three analyzers were collected. Measurements from the Quantum and the CDI 500 were averaged over 1 minute to provide a single value for the minute for the given device. Blood analysis on the ABL90 benchtop device was performed at a minimum of every hour during congenital cardiopulmonary bypass (CPB). There were 519 patients included in the analysis. Data points numbering 69,404 and 70,598 were analyzed when comparing the CDI 500 to the Quantum for hemoglobin and SvO2, respectively. Comparison of hemoglobin and SvO2 for the CDI 500 and Quantum versus ABL90 used 2283 and 1414 data points respectively, in each group. The CDI 500 and Quantum reported hemoglobin within 1 g/dL of the ABL90 86.9% and 87.5% of the time, respectively. The CDI 500 and Quantum reported SvO2 within 3% of the ABL90 61.0% and 57.9% of the time, respectively. The mean difference between the CDI 500 and Quantum hemoglobin and SvO2 measurements equaled .194 g/dL (p < .001) and .861% (p < .001), respectively and were both significantly different from zero. All device comparisons were statistically significantly different when compared to zero difference, likely due to the large data set as the magnitudes of these differences are all quite small and may not be clinically significant. However, while the reader should judge for themselves based upon their specific practice, in our opinion, the 95% Limit of Agreement was too large for either the CDI 500 or Quantum hemoglobin and SvO2 values to be substituted for ABL90 values. As recommended by the manufacturers, the CDI 500 and Quantum should only be used as a trending device.

The Optimal Cell Salvage Settings to Maximize Hematocrit and Minimize Potassium Using the Cobe BRAT2 Autologous Blood Recovery Unit

OBJECTIVE

The objective was to determine the optimal cell saver device settings (infusion rate and wash rate) at which hematocrit is preserved and potassium and lactate are removed from banked red blood cells (RBC).

DESIGN

Red cells were washed using the Cobe BRAT 2 Autologous Blood Recovery Unit and sampled for electrolyte composition and hematocrit pre- and postwash.

SETTING

This was a single-center study.

INTERVENTIONS

Red cells were washed using six infusion rates (100-1,000 mL/min) and six wash rates (100-1,000 mL/min) for a total of 36 combinations. Hematocrit, potassium, glucose, and lactate were evaluated before and after washing.

MEASUREMENTS AND MAIN RESULTS

At wash rates ≤400 mL/min, hematocrit increased independent of infusion rate. At wash rates ≥400 mL/min, slower infusion rates were associated with higher hematocrit compared to faster infusion rates (p < 0.0001 for a wash rate 400-800 mL/min, p < 0.0005 for a wash rate 1,000 mL/min). Maximal wash speeds were associated with decreasing hematocrit. Infusion and wash rate were both independent predictors of potassium change; slower rates were associated with a larger decrease in potassium. Glucose decreased proportionally as infusion and wash rate decreased. Lactate did not show an association with either infusion or wash rate.

CONCLUSION

Red-cell washing produces higher hematocrit and lower potassium as infusion rate and wash rate decrease. A 340-mL unit of RBC can be processed in 4.26 minutes without loss of hematocrit or an increase in potassium when both infusion and wash rates are set to 400 mL/min.

Bedside Allogeneic Erythrocyte Washing with a Cell Saver to Remove Cytokines, Chemokines, and Cell-derived Microvesicles

BACKGROUND

Removal of cytokines, chemokines, and microvesicles from the supernatant of allogeneic erythrocytes may help mitigate adverse transfusion reactions. Blood bank-based washing procedures present logistical difficulties; therefore, we tested the hypothesis that on-demand bedside washing of allogeneic erythrocyte units is capable of removing soluble factors and is feasible in a clinical setting.

METHODS

There were in vitro and prospective, observation cohort components to this a priori planned substudy evaluating bedside allogeneic erythrocyte washing, with a cell saver, during cardiac surgery. Laboratory data were collected from the first 75 washed units given to a subset of patients nested in the intervention arm of a parent clinical trial. Paired pre- and postwash samples from the blood unit bags were centrifuged. The supernatant was aspirated and frozen at -70°C, then batch-tested for cell-derived microvesicles, soluble CD40 ligand, chemokine ligand 5, and neutral lipids (all previously associated with transfusion reactions) and cell-free hemoglobin (possibly increased by washing). From the entire cohort randomized to the intervention arm of the trial, bedside washing was defined as feasible if at least 75% of prescribed units were washed per protocol.

RESULTS

Paired data were available for 74 units. Washing reduced soluble CD40 ligand (median [interquartile range]; from 143 [1 to 338] ng/ml to zero), chemokine ligand 5 (from 1,314 [715 to 2,551] to 305 [179 to 488] ng/ml), and microvesicle numbers (from 6.90 [4.10 to 20.0] to 0.83 [0.33 to 2.80] × 106), while cell-free hemoglobin concentration increased from 72.6 (53.6 to 171.6) mg/dl to 210.5 (126.6 to 479.6) mg/dl (P < 0.0001 for each). There was no effect on neutral lipids. Bedside washing was determined as feasible for 80 of 81 patients (99%); overall, 293 of 314 (93%) units were washed per protocol.

CONCLUSIONS

Bedside erythrocyte washing was clinically feasible and greatly reduced concentrations of soluble factors thought to be associated with transfusion-related adverse reactions, increasing concentrations of cell-free hemoglobin while maintaining acceptable (less than 0.8%) hemolysis.

EDITOR’S PERSPECTIVE

[Cell salvage : Scientific evidence, clinical practice and legal framework]

Cell salvage is an efficient method to reduce the transfusion of homologous banked blood, as documented by several meta-analyses detected in a systematic literature search. Cell salvage is widely used in orthopedics, trauma surgery, cardiovascular and abdominal transplantation surgery. The retransfusion of unwashed shed blood from wounds or drainage is not permitted according to German regulations. Following irradiation of wound blood, salvaged blood can also be used in tumor surgery. Cell salvage makes a valuable contribution to providing sufficient compatible blood for transfusions in cases of massive blood loss. Certain surgical procedures for Jehovah's Witnesses are only possible with the use of cell salvage. Another possible use is the washing of homologous banked blood, e. g. to prevent potassium-induced arrhythmia or sequestration of autologous platelets. Other advantages besides a good compatibility are the high vitality and functionality of the unstored autologous red blood cells. These have been declared a pharmaceutical product by the German transfusion task force in 2014, so that the autologous red blood cells are now under the control of the Pharmaceutical Products Act (AMG). The new hemotherapy guidelines, however, tolerate cell salvage only under strict rules, whereby the production of autologous blood during or after surgery is still possible without additional special permits. The new guidelines now require the introduction of a quality management system for cell salvage and regular quality controls. These quality controls include a control of the product hematocrit for every application, monthly controls of the protein and albumin elimination rates and the erythrocyte recovery rate for each cell salvage device. Testing for infection markers is not required. The application of cell salvage has to be reported to the appropriate authorities.

Washing or filtering of blood products does not improve outcome in a rat model of trauma and multiple transfusion

BACKGROUND

Transfusion is associated with organ failure and nosocomial infection in trauma patients, which may be mediated by soluble bioactive substances in blood products, including extracellular vesicles (EVs). We hypothesize that removing EVs, by washing or filtering of blood products, reduces organ failure and improves host immune response.

MATERIALS AND METHODS

Blood products were prepared from syngeneic rat blood. EVs were removed from RBCs and platelets by washing. Plasma was filtered through a 0.22‐μm filter. Rats were traumatized by crush injury to the intestines and liver, and a femur was fractured. Rats were hemorrhaged until a mean arterial pressure of 40 mm Hg and randomized to receive resuscitation with standard or washed/filtered blood products, in a 1:1:1 ratio. Sham controls were not resuscitated. Ex vivo whole blood stimulation tests were performed and histopathology was done.

RESULTS

Washing of blood products improved quality metrics compared to standard products. Also, EV levels reduced by 12% to 77%. The coagulation status, as assessed by thromboelastometry, was deranged in both groups and normalized during transfusion, without significant differences. Use of washed/filtered products did not reduce organ failure, as assessed by histopathologic score and biochemical measurements. Immune response ex vivo was decreased following transfusion compared to sham but did not differ between transfusion groups.

CONCLUSION

Filtering or washing of blood products improved biochemical properties and reduced EV counts, while maintaining coagulation abilities. However, in this trauma and transfusion model, the use of optimized blood components did not attenuate organ injury or immune suppression.

Centrifugation-free washing: A novel approach for removing immunoglobulin A from stored red blood cells

Washed red blood cells (RBCs) are indicated for immunoglobulin A (IgA) deficient recipients. Centrifugation-based cell processors commonly used by hospital blood banks cannot consistently reduce IgA below the recommended levels, hence double washing is frequently required. Here, we describe a prototype of a simple, portable, disposable system capable of washing stored RBCs without centrifugation, while reducing IgA below 0.05 mg/dL in a single run. Samples from RBC units (n = 8, leukoreduced, 4-6 weeks storage duration) were diluted with normal saline to a hematocrit of 10%, and then washed using either the prototype washing system, or via conventional centrifugation. The efficiency of the two washing methods was quantified and compared by measuring several key in vitro quality metrics. The prototype of the washing system was able to process stored RBCs at a rate of 300 mL/hour, producing a suspension of washed RBCs with 43 ± 3% hematocrit and 86 ± 7% cell recovery. Overall, the two washing methods performed similarly for most measured parameters, lowering the concentration of free hemoglobin by >4-fold and total free protein by >10-fold. Importantly, the new washing system reduced the IgA level to 0.02 ± 0.01 mg/mL, a concentration 5-fold lower than that produced by conventional centrifugation. This proof-of-concept study showed that centrifugation may be unnecessary for washing stored RBCs. A simple, disposable, centrifugation-free washing system could be particularly useful in smaller medical facilities and resource limited settings that may lack access to centrifugation-based cell processors.

Rapid bedside rejuvenation of red blood cell with an autologous cell salvage device

BACKGROUND AND OBJECTIVES

During storage, red blood cells (RBCs) undergo physicochemical changes which affect the quality, function, and in vivo survival of transfused packed RBCs (pRBC). Changes include decreased 2,3-diphosphoglycerate (2,3-DPG) levels, decreased ATP, changes in mechanical properties and oxidative injury. RBC rejuvenation is a method used to increase levels of 2,3-DPG and ATP in pRBCs. This process requires incubating the pRBCs with a rejuvenation solution and subsequent washing. Standard blood bank protocols using the COBE 2991 Cell Processor require several hours of preparation. The objective of this study was to verify if a bedside protocol for rejuvenating pRBC and washing with the Sorin Xtra autologous cell salvage system could be used.

MATERIALS AND METHODS

Outdated pRBC units were obtained and rejuvenated in a model operating suite using a dry air incubator for 1 h at 37°C. Six units of pRBCs were pre-diluted with saline (1000 ml) and six units were not pre-diluted with saline. All units were washed with normal saline (1000 ml) using an apheresis-design cell salvage device in manual mode and wash volume set to 3000 ml. Samples were collected and analyzed for standard RBC quality parameters at baseline and post-wash.

RESULTS

Total pRBC wash efficiency was 94% ± 12% at a final hematocrit of 67.7 ± 5.9% while maintaining post-wash hemolysis 0.24 ± 0.12 %. Pre-dilution prior to washing did not confer statistically significant differences in final RBC quality parameters with the notable exceptions of calculated hemolysis and supernatant potassium levels (P < 0.05). The washing process can be completed within 10 min. The post-wash RBC parameters are appropriate for immediate transfusion to patients.

Intraoperative management of liver transplant recipients having severe renal dysfunction: results of 42 cases

Purpose

Whereas continuous renal replacement therapy (CRRT) has been utilized during liver transplantation (LT), there was a lack of evidence to support this practice. We investigated the adverse events at the perioperative periods in recipients of LT who received preoperative CRRT without intraoperative CRRT.

Methods

We retrospectively reviewed medical records of adult patients (age ≥ 18 years) who received LT between December 2009 and May 2015. Perioperative data were collected from the recipients, who received preoperative CRRT until immediately before LT, because of refractory renal dysfunction.

Results

Of 706 recipients, 42 recipients received preoperative CRRT. The mean (standard deviation) Model for end-stage liver disease score were 49.6 (13.4). Twenty-six point two percent (26.2%) of recipients experienced the serum potassium > 4.5 mEq/L before reperfusion and treated with regular insulin. Thirty-eight point one percent (38.1%) of recipients were managed with sodium bicarbonate because of acidosis (base excess < −10 mEq/L throughout LT). All patients finished their operations without medically uncontrolled complications such as severe hyperkalemia (serum potassium > 5.5 mEq/L), refractory acidosis, or critical arrhythmias. Mortality was 19% at 30 day and 33.3% at 1 year.

Conclusion

Although intraoperative CRRT was not used in recipients with severe preoperative renal dysfunction, LT was safely performed. Our experience raises a question about the need for intraoperative CRRT.

Estimation of Achievable Oxygen Consumption Following Transfusion With Rejuvenated Red Blood Cells

Erythrocyte storage induces a nonphysiological increase in hemoglobin-oxygen affinity (quantified by low p50, the oxygen tension at 50% hemoglobin saturation), which can be restored through biochemical rejuvenation. The objective was to mathematically model the impact of transfusing up to 3 standard allogeneic units or rejuvenated units on oxygen delivery (DO₂) and oxygen consumption (VO₂). Oxygen dissociation curves were generated from additive solution-1 red blood cell (RBC) leukoreduced units (n = 7) before and after rejuvenation following manufacturer's instructions. Two of these units were used to prepare standard or rejuvenated donor RBC and added to samples of fresh whole blood. These admixtures were used to construct an in vitro transfusion model of postoperative anemia and determine a linear equation for calculating the sample p50, which was subsequently used to calculate DO₂ and VO₂ after simulated transfusions. Whole blood-packed red blood cell unit admixture p50s could be predicted from a linear model including the p50 of its components, the mass fraction of the transfused component, and interaction terms (R² = .99, P < 0.001). Transfusion with standard units slightly, but significantly, increased projected DO₂ compared with rejuvenated units (P = 0.03), but rejuvenated units markedly increased projected VO₂ (P = 0.03). Standard units did not significantly change VO₂ relative to pre-transfusion levels (P > 0.1). Using high-p50, rejuvenated RBC in simulated transfusions greatly improved projected VO₂, indicating the potential for increased end-organ oxygen availability compared with standard transfusion. Patient capacity to increase cardiac output after cardiac surgery may be limited. Transfusing high-p50 RBC in this setting may improve the perioperative care of these patients.

Towards bedside washing of stored red blood cells: a prototype of a simple apparatus based on microscale sedimentation in normal gravity

BACKGROUND AND OBJECTIVES

Infusion of by-products of red blood cell (RBC) storage-induced degradation as well as of the residual plasma proteins and the anticoagulant-preservative solution contained in units of stored blood serve no therapeutic purpose and may be harmful to some patients. Here, we describe a prototype of a gravity-driven system for bedside washing of stored RBCs.

MATERIALS AND METHODS

Stored RBCs were diluted to 10% haematocrit (Hct) with normal saline, matching the conventional washing procedure. The dilute RBC suspensions were passed through a column of coiled tubing to allow RBC sedimentation in normal gravity, thus separating them from the washing solution. Washed RBCs were collected using bifurcations located along the tubing. Washing efficiency was quantified by measuring Hct, morphology, deformability, free haemoglobin and total-free protein.

RESULTS

The gravity-driven washing system operating at 0·5 ml/min produced washed RBCs with final Hct of 36·7 ± 3·4% (32·3-41·2%, n = 10) and waste Hct of 3·4 ± 0·7% (2·4-4·3%, n = 10), while removing 80% of free haemoglobin and 90% of total-free protein. Washing improved the ability of stored RBCs to perfuse an artificial microvascular network by 20%. The efficiency of washing performed using the gravity-driven system was not significantly different than that of conventional centrifugation.

CONCLUSIONS

This proof-of-concept study demonstrates the feasibility of washing stored RBCs using a simple, disposable system with efficiency comparable to that of conventional centrifugation, and thus represents a significant first step towards enabling low-cost washing of stored blood at bedside.

A new approach for fat removal in a discontinuous autotransfusion device-concept and evaluation

BACKGROUND

Fat present during blood salvage in orthopaedic or cardiac surgery can pose a risk of fat embolism and should be eliminated before transfusion. Based on observations of central fat accumulation at the bottom of Latham bowls, a fat reduction program was developed using two volume displacements, where blood temporarily is removed and respun in the bowl to force the fat through the RBC sediment.

MATERIALS AND METHODS

Pooled ABO-matched RBC and FFP were adjusted to a haematocrit of 10%, and human fat tissue added to a concentration of 1·25 vol%. In six experiments, blood was processed with the new-generation cell salvage device CS Elite in a newly developed fat reduction program in bowls of three sizes. Volumetric quantification of fat was performed after centrifugation of blood samples in Pasteur pipettes. From volumes, haematocrits and the concentrations of fat, RBC recovery and fat elimination rates were calculated.

RESULTS

Fat removal rates of 93·2 ± 2·8, 97·0 ± 2·1 and 99·6 ± 0·3% were observed with a 70-ml, 125-ml and 225-ml bowl, respectively, and even higher rates when removal rates were calculated one cycle. At the same time, high RBC recovery and plasma elimination rates were maintained, not significantly different to the default program mode.

CONCLUSION

Modifications in process parameters and sequence led to a fat reduction program that significantly improves fat removal with the Cell Saver Elite from 77·4 ± 5·1% in the default mode to an average of 98·6 ± 1·1%, yielding results equivalent to the continuous cell salvage system (C.A.T.S).

Point-of-care washing of allogeneic red blood cells for the prevention of transfusion-related respiratory complications (WAR-PRC): a protocol for a multicenter randomised clinical trial in patients undergoing cardiac surgery

INTRODUCTION

The transfusion-related respiratory complications, transfusion-related acute lung injury (TRALI) and transfusion-associated circulatory overload (TACO), are leading causes of transfusion-related morbidity and mortality. At present, there are no effective preventive strategies with red blood cell (RBC) transfusion. Although mechanisms remain incompletely defined, soluble biological response modifiers (BRMs) within the RBC storage solution may play an important role. Point-of-care (POC) washing of allogeneic RBCs may remove these BRMs, thereby mitigating their impact on post-transfusion respiratory complications.

METHODS AND ANALYSIS

This is a multicenter randomised clinical trial of standard allogeneic versus washed allogeneic RBC transfusion for adult patients undergoing cardiac surgery testing the hypothesis that POC RBC washing is feasible, safe, and efficacious and will reduce recipient immune and physiologic responses associated with transfusion-related respiratory complications. Relevant clinical outcomes will also be assessed. This investigation will enrol 170 patients at two hospitals in the USA. Simon's two-stage design will be used to assess the feasibility of POC RBC washing. The primary safety outcomes will be assessed using Wilcoxon Rank-Sum tests for continuous variables and Pearson chi-square test for categorical variables. Standard mixed modelling practices will be employed to test for changes in biomarkers of lung injury following transfusion. Linear regression will assess relationships between randomised group and post-transfusion physiologic measures.

ETHICS AND DISSEMINATION

Safety oversight will be conducted under the direction of an independent Data and Safety Monitoring Board (DSMB). Approval of the protocol was obtained by the DSMB as well as the institutional review boards at each institution prior to enrolling the first study participant. This study aims to provide important information regarding the feasibility of POC washing of allogeneic RBCs and its potential impact on ameliorating post-transfusion respiratory complications. Additionally, it will inform the feasibility and scientific merit of pursuing a more definitive phase II/III clinical trial.

REGISTRATION

ClinicalTrials.gov registration number is NCT02094118 (Pre-results).

Performance of a new-generation continuous autotransfusion device including fat removal and consequences for quality controls

BACKGROUND AND OBJECTIVES

Cell salvage plays a key role in blood conservation. To maintain high performance, quality management is recommended. Accordingly, a new-generation autotransfusion device was tested for its performance and compared with its predecessor. Two different calculations of quality parameters were applied.

MATERIALS AND METHODS

In an experimental study, the continuous autotransfusion devices CATSmart and Continuous Autotransfusion System (C.A.T.S) plus were tested using banked blood adjusted to a haematocrit of 20% and anticoagulated with heparin 5 U/L. Test blood was processed using an emergency programme, a high-quality programme/smart wash programme and a low-volume wash programme. Samples were taken after the production of 200 mL of red blood cells (RBC) and after the final emptying of the separation chamber. In an additional set of tests, blood containing 1·25% fat was processed with both devices to examine fat removal.

RESULTS

Both devices demonstrated an equally high performance with regards to product hematocrit (Hct); RBC recovery; and elimination rates of protein, heparin and fat. The high fat elimination rate (>99·8%) reported for C.A.T.S plus was confirmed for CATSmart, regardless of the used programme. Samples taken during the ongoing process show a higher haematocrit and RBC recovery rate than samples taken after the final emptying of the separation chamber. Interface sensors were not affected by fat in the blood.

CONCLUSIONS

The new-generation autotransfusion device CATSmart is not inferior to its predecessor and shows high performance with regards to RBC recovery, plasma and fat elimination in all programme modes. Samples for quality controls should be taken during blood processing.

Washing in hypotonic saline reduces the fraction of irreversibly-damaged cells in stored blood: a proof-of-concept study

BACKGROUND

During hypothermic storage, a substantial fraction of red blood cells (RBCs) transforms from flexible discocytes to rigid sphero-echinocytes and spherocytes. Infusion of these irreversibly-damaged cells into the recipient during transfusion serves no therapeutic purpose and may contribute to adverse outcomes in some patients. In this proof-of-concept study we describe the use of hypotonic washing for selective removal of the irreversibly-damaged cells from stored blood.

MATERIALS AND METHODS

Stored RBCs were mixed with saline of various concentrations to identify optimal concentration for inducing osmotic swelling and selective bursting of spherical cells (sphero-echinocytes, spherocytes), while minimising indiscriminate lysis of other RBCs. Effectiveness of optimal treatment was assessed by measuring morphology, rheological properties, and surface phosphatidylserine (PS) exposure for cells from several RBCs units (n=5, CPD>AS-1, leucoreduced, 6 weeks storage duration) washed in hypotonic vs isotonic saline.

RESULTS

Washing in mildly hypotonic saline (0.585 g/dL, osmolality: 221.7±2.3 mmol/kg) reduced the fraction of spherical cells 3-fold from 9.5±3.4% to 3.2±2.8%, while cutting PS exposure in half from 1.48±0.86% to 0.59±0.29%. Isotonic washing had no effect on PS exposure or the fraction of spherical cells. Both isotonic and hypotonic washing increased the fraction of well-preserved cells (discocytes, echinocytes 1) substantially, and improved the ability of stored RBCs to perfuse an artificial microvascular network by approximately 25%, as compared with the initial sample.

DISCUSSION

This study demonstrated that washing in hypotonic saline could selectively remove a significant fraction of the spherical and PS-exposing cells from stored blood, while significantly improving the rheological properties of remaining well-preserved RBCs. Further studies are needed to access the potential effect from hypotonic washing on transfusion outcomes.

Quality Assessment of Established and Emerging Blood Components for Transfusion

Blood is donated either as whole blood, with subsequent component processing, or through the use of apheresis devices that extract one or more components and return the rest of the donation to the donor. Blood component therapy supplanted whole blood transfusion in industrialized countries in the middle of the twentieth century and remains the standard of care for the majority of patients receiving a transfusion. Traditionally, blood has been processed into three main blood products: red blood cell concentrates; platelet concentrates; and transfusable plasma. Ensuring that these products are of high quality and that they deliver their intended benefits to patients throughout their shelf-life is a complex task. Further complexity has been added with the development of products stored under nonstandard conditions or subjected to additional manufacturing steps (e.g., cryopreserved platelets, irradiated red cells, and lyophilized plasma). Here we review established and emerging methodologies for assessing blood product quality and address controversies and uncertainties in this thriving and active field of investigation.

Fat removal during cell salvage: an optimized program for a discontinuous autotransfusion device

BACKGROUND

Fat in wound blood observed in orthopedic or cardiac surgery might pose a risk for fat embolism during blood salvage. Fat removal was optimized in the washing process.

STUDY DESIGN AND METHODS

In an experimental study blood from fresh donations was adjusted to a hematocrit (Hct) of 25% and an admixture of 1.25% human tissue fat. This blood was processed with the cell salvage device XTRA in a modified program mode. Volumetric quantification of fat was performed after centrifugation of blood samples in Pasteur pipettes. From the volumes, the Hct levels and the concentrations of fat and other variables elimination rates and RBC recovery were calculated.

RESULTS

Pretests showed wash volume, wash flow, and process interruptions affecting fat elimination. With the new optimized fat elimination program Pfat removal rate of fat increased to 98.5 ± 0.9% for the 225-mL bowl. The product had a mean Hct of 48.7 ± 1.2% and a RBC recovery rate of 93.5 ± 2.3%. The program conserved the high elimination rates for albumin, heparin, potassium, and free plasma hemoglobin (98.8, 99.3, 95.3, and 94.9%, respectively). Similar high fat removal was also observed with bowls of smaller size, namely, 98.1% for the 175-mL bowl and 98.2% for the 125- and the 55-mL bowls. With test blood of Hct 10% a mean fat elimination of 99.6 ± 01% was observed.

CONCLUSIONS

A special program modification Pfat involving extra washing and RBC concentration steps significantly improves fat removal by the Latham bowl-based autotransfusion device XTRA, thus yielding results equivalent to the continuous cell salvage system.

Antibody-mediated transfusion-related acute lung injury; from discovery to prevention

Transfusion-related acute lung injury (TRALI), a syndrome of respiratory distress caused by blood transfusion, is the leading cause of transfusion-related mortality. The majority of TRALI cases have been related to passive infusion of human leucocyte antigen (HLA) and human neutrophil antigen (HNA) antibodies in donor blood. In vitro, ex vivo and in vivo animal models have provided insight in TRALI pathogenesis. The various classes of antibodies implicated in TRALI appear to have different pathophysiological mechanisms for the induction of TRALI involving endothelial cells, neutrophils, monocytes and, as very recently has been discovered, lymphocytes. The HLA and HNA-antibodies are found mainly in blood from multiparous women as they have become sensitized during pregnancy. The incidence of TRALI has decreased rapidly following the introduction of a male-only strategy for plasma donation. This review focuses on pre-clinical and clinical studies investigating the pathophysiology of antibody-mediated TRALI.

Minimizing transfusion requirements for children undergoing craniosynostosis repair: the CHoR protocol

OBJECT

Children with craniosynostosis may require cranial vault remodeling to prevent or relieve elevated intracranial pressure and to correct the underlying craniofacial abnormalities. The procedure is typically associated with significant blood loss and high transfusion rates. The risks associated with transfusions are well documented and include transmission of infectious agents, bacterial contamination, acute hemolytic reactions, transfusion-related lung injury, and transfusion-related immune modulation. This study presents the Children's Hospital of Richmond (CHoR) protocol, which was developed to reduce the rate of blood transfusion in infants undergoing primary craniosynostosis repair.

METHODS

A retrospective chart review of pediatric patients treated between January 2003 and Febuary 2012 was performed. The CHoR protocol was instituted in November 2008, with the following 3 components; 1) the use of preoperative erythropoietin and iron therapy, 2) the use of an intraoperative blood recycling device, and 3) acceptance of a lower level of hemoglobin as a trigger for transfusion (< 7 g/dl). Patients who underwent surgery prior to the protocol implementation served as controls.

RESULTS

A total of 60 children were included in the study, 32 of whom were treated with the CHoR protocol. The control (C) and protocol (P) groups were comparable with respect to patient age (7 vs 8.4 months, p = 0.145). Recombinant erythropoietin effectively raised the mean preoperative hemoglobin level in the P group (12 vs 9.7 g/dl, p < 0.001). Although adoption of more aggressive surgical vault remodeling in 2008 resulted in a higher estimated blood loss (212 vs 114.5 ml, p = 0.004) and length of surgery (4 vs 2.8 hours, p < 0.001), transfusion was performed in significantly fewer cases in the P group (56% vs 96%, p < 0.001). The mean length of stay in the hospital was shorter for the P group (2.6 vs 3.4 days, p < 0.001).

CONCLUSIONS

A protocol that includes preoperative administration of recombinant erythropoietin, intraoperative autologous blood recycling, and accepting a lower transfusion trigger significantly decreased transfusion utilization (p < 0.001). A decreased length of stay (p < 0.001) was seen, although the authors did not investigate whether composite transfusion complication reductions led to better outcomes.

Washing older blood units before transfusion reduces plasma iron and improves outcomes in experimental canine pneumonia

In a randomized controlled blinded trial, 2-year-old purpose-bred beagles (n = 24), with Staphylococcus aureus pneumonia, were exchanged-transfused with either 7- or 42-day-old washed or unwashed canine universal donor blood (80 mL/kg in 4 divided doses). Washing red cells (RBC) before transfusion had a significantly different effect on canine survival, multiple organ injury, plasma iron, and cell-free hemoglobin (CFH) levels depending on the age of stored blood (all, P < .05 for interactions). Washing older units of blood improved survival rates, shock score, lung injury, cardiac performance and liver function, and reduced levels of non-transferrin bound iron and plasma labile iron. In contrast, washing fresh blood worsened all these same clinical parameters and increased CFH levels. Our data indicate that transfusion of fresh blood, which results in less hemolysis, CFH, and iron release, is less toxic than transfusion of older blood in critically ill infected subjects. However, washing older blood prevented elevations in plasma circulating iron and improved survival and multiple organ injury in animals with an established pulmonary infection. Our data suggest that fresh blood should not be washed routinely because, in a setting of established infection, washed RBC are prone to release CFH and result in worsened clinical outcomes.