Plasma from aged stored red blood cells delays neutrophil apoptosis and primes for cytotoxicity: abrogation by poststorage washing but not prestorage leukoreduction

Study protocol of the WashT Trial: transfusion with washed versus unwashed red blood cells to reduce morbidity and mortality in infants born less than 28 weeks' gestation - a multicentre, blinded, parallel group, randomised controlled trial

INTRODUCTION

Many extremely preterm newborns develop anaemia requiring a transfusion, with most receiving three to five transfusions during their admission. While transfusions save lives, the potential for transfusion-related adverse outcomes is an area of growing concern. Transfusion is an independent predictor of death and is associated with increased morbidity, length of hospital stay, risk of infection and immune modulation. The underlying mechanisms include adverse pro-inflammatory and immunosuppressive responses. Evidence supports an association between transfusion of washed red cells and fewer post-transfusion complications potentially through removal of chemokines, lipids, microaggregates and other biological response modifiers. However, the clinical and cost-effectiveness of washed cells have not been determined.

METHODS AND ANALYSIS

This is a multicentre, randomised, double-blinded trial of washed versus unwashed red cells. Infants <28 weeks' gestation requiring a transfusion will be enrolled. Transfusion approaches will be standardised within each study centre and will occur as soon as possible with a recommended fixed transfusion volume of 15 mL/kg whenever the haemoglobin is equal to or falls below a predefined restrictive threshold, or when clinically indicated. The primary outcome is a composite of mortality and/or major morbidity to first discharge home, defined as one or more of the following: physiologically defined bronchopulmonary dysplasia; unilateral or bilateral retinopathy of prematurity grade >2, and; necrotising enterocolitis stage ≥2. To detect a 10% absolute reduction in the composite outcome from 69% with unwashed red blood cell (RBCs) to 59% with washed RBCs with 90% power, requires a sample size of 1124 infants (562 per group). Analyses will be performed on an intention-to-treat basis with a prespecified statistical analysis plan. A cost-effectiveness analysis will also be undertaken.

ETHICS AND DISSEMINATION

Ethics approval has been obtained from the Women's and Children's Health Network Human Research Ethics Committee (HREC/12/WCHN/55). The study findings will be disseminated through peer-reviewed articles and conferences.

TRIAL REGISTRATION NUMBER

ACTRN12613000237785 Australian New Zealand Clinical Trials Registry.

A 3D-printed transfusion platform reveals beneficial effects of normoglycemic erythrocyte storage solutions and a novel rejuvenating solution

A set of 3D-printed analytical devices were developed to investigate erythrocytes (ERYs) processed in conventional and modified storage solutions used in transfusion medicine. During storage, prior to transfusion into a patient recipient, ERYs undergo many chemical and physical changes that are not completely understood. However, these changes are thought to contribute to an increase in post-transfusion complications, and even an increase in mortality rates. Here, a reusable fluidic device (fabricated with additive manufacturing technologies) enabled the evaluation of ERYs prior to, and after, introduction into a stream of flowing fresh ERYs, thus representing components of an in vivo ERY transfusion on an in vitro platform. Specifically, ERYs stored in conventional and glucose-modified solutions were assayed by chemiluminescence for their ability to release flow-induced ATP. The ERY's deformability was also determined throughout the storage duration using a novel membrane transport approach housed in a 3D-printed scaffold. Results show that hyperglycemic conditions permanently alter ERY deformability, which may explain the reduced ATP release, as this phenomenon is related to cell deformability. Importantly, the reduced deformability and ATP release were reversible in an in vitro model of transfusion; specifically, when stored cells were introduced into a flowing stream of healthy cells, the ERY-derived release of ATP and cell deformability both returned to states similar to that of non-stored cells. However, after 1-2 weeks of storage, the deleterious effects of the storage were permanent. These results suggest that currently approved hyperglycemic storage solutions are having adverse effects on stored ERYs used in transfusion medicine and that normoglycemic storage may reduce the storage lesion, especially for cells stored for longer than 14 days.

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

The emerging role of red blood cells in cytokine signalling and modulating immune cells

For many years red blood cells have been described as inert bystanders rather than participants in intercellular signalling, immune function, and inflammatory processes. However, studies are now reporting that red blood cells from healthy individuals regulate immune cell activity and maturation, and red blood cells from disease cohorts are dysfunctional. These cells have now been shown to bind more than 50 cytokines and have been described as a sink for these molecules, and the loss of this activity has been correlated with disease progression. In this review, we summarise what is currently understood about the role of red blood cells in cytokine signalling and in modulating the activity of immune cells. We also discuss the implications of these findings for transfusion medicine and in furthering our understanding of anaemia of chronic inflammation. By bringing these disparate units of work together, we aim to shine a light on an area that requires significantly more investigation.

The Effects of Storage Age of Blood in Massively Transfused Burn Patients: A Secondary Analysis of the Randomized Transfusion Requirement in Burn Care Evaluation Study

OBJECTIVES

Major trials examining storage age of blood transfused to critically ill patients administered relatively few blood transfusions. We sought to determine if the storage age of blood affects outcomes when very large amounts of blood are transfused.

DESIGN

A secondary analysis of the multicenter randomized Transfusion Requirement in Burn Care Evaluation study which compared restrictive and liberal transfusion strategies.

SETTING

Eighteen tertiary-care burn centers.

PATIENTS

Transfusion Requirement in Burn Care Evaluation evaluated 345 adults with burns greater than or equal to 20% of the body surface area. We included only the 303 patients that received blood transfusions.

INTERVENTIONS

The storage ages of all transfused red cell units were collected during Transfusion Requirement in Burn Care Evaluation. A priori measures of storage age were the the mean storage age of all transfused blood and the proportion of all transfused blood considered very old (stored ≥ 35 d).

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the severity of multiple organ dysfunction. Secondary outcomes included time to wound healing, the duration of mechanical ventilation, and in-hospital mortality. There were 6,786 red cell transfusions with a mean (± SD) storage age of 25.6 ± 10.2 days. Participants received a mean of 23.4 ± 31.2 blood transfusions (range, 1-219) and a mean of 5.3 ± 10.7 units of very old blood. Neither mean storage age nor proportion of very old blood had any influence on multiple organ dysfunction severity, time to wound healing, or mortality. Duration of ventilation was significantly predicted by both mean blood storage age and the proportion of very old blood, but this was of questionable clinical relevance given extreme variability in duration of ventilation (adjusted r ≤ 0.01).

CONCLUSIONS

Despite massive blood transfusion, including very old blood, the duration of red cell storage did not influence outcome in burn patients. Provision of the oldest blood first by Blood Banks is rational, even for massive transfusion.

The contribution of red blood cell transfusion to neonatal morbidity and mortality

Anaemia of prematurity will affect 90% of all very preterm infants, resulting in at least one red blood cell (RBC) transfusion. A significant proportion of preterm infants require multiple transfusions over the course of hospital admission. Growing evidence supports an association between transfusion exposure and adverse neonatal outcomes. In adults, transfusion-associated sepsis, transfusion-related acute lung injury and haemolytic reactions are the leading causes of transfusion-related morbidity and mortality; however, these are seldom recognised in newborns. The association between transfusion and adverse outcomes remains inconclusive. However, the evidence from preclinical studies demonstrates that RBC products can directly modulate immune cell function, a pathway termed transfusion-related immunomodulation (TRIM), which may provide a mechanism linking transfusion exposure with neonatal morbidities. Finally, we discuss the impact of TRIM on transfusion medicine, how we may address these issues and the emerging areas of research aimed at improving the safety of transfusions in this vulnerable population.

Role of heme in lung bacterial infection after trauma hemorrhage and stored red blood cell transfusion: A preclinical experimental study

BACKGROUND

Trauma is the leading cause of death and disability in patients aged 1-46 y. Severely injured patients experience considerable blood loss and hemorrhagic shock requiring treatment with massive transfusion of red blood cells (RBCs). Preclinical and retrospective human studies in trauma patients have suggested that poorer therapeutic efficacy, increased severity of organ injury, and increased bacterial infection are associated with transfusion of large volumes of stored RBCs, although the mechanisms are not fully understood.

METHODS AND FINDINGS

We developed a murine model of trauma hemorrhage (TH) followed by resuscitation with plasma and leukoreduced RBCs (in a 1:1 ratio) that were banked for 0 (fresh) or 14 (stored) days. Two days later, lungs were infected with Pseudomonas aeruginosa K-strain (PAK). Resuscitation with stored RBCs significantly increased the severity of lung injury caused by P. aeruginosa, as demonstrated by higher mortality (median survival 35 h for fresh RBC group and 8 h for stored RBC group; p < 0.001), increased pulmonary edema (mean [95% CI] 106.4 μl [88.5-124.3] for fresh RBCs and 192.5 μl [140.9-244.0] for stored RBCs; p = 0.003), and higher bacterial numbers in the lung (mean [95% CI] 1.2 × 10(7) [-1.0 × 10(7) to 2.5 × 10(7)] for fresh RBCs and 3.6 × 10(7) [2.5 × 10(7) to 4.7 × 10(7)] for stored RBCs; p = 0.014). The mechanism underlying this increased infection susceptibility and severity was free-heme-dependent, as recombinant hemopexin or pharmacological inhibition or genetic deletion of toll-like receptor 4 (TLR4) during TH and resuscitation completely prevented P. aeruginosa-induced mortality after stored RBC transfusion (p < 0.001 for all groups relative to stored RBC group). Evidence from studies transfusing fresh and stored RBCs mixed with stored and fresh RBC supernatants, respectively, indicated that heme arising both during storage and from RBC hemolysis post-resuscitation plays a role in increased mortality after PAK (p < 0.001). Heme also increased endothelial permeability and inhibited macrophage-dependent phagocytosis in cultured cells. Stored RBCs also increased circulating high mobility group box 1 (HMGB1; mean [95% CI] 15.4 ng/ml [6.7-24.0] for fresh RBCs and 50.3 ng/ml [12.3-88.2] for stored RBCs), and anti-HMGB1 blocking antibody protected against PAK-induced mortality in vivo (p = 0.001) and restored macrophage-dependent phagocytosis of P. aeruginosa in vitro. Finally, we showed that TH patients, admitted to the University of Alabama at Birmingham ER between 1 January 2015 and 30 April 2016 (n = 50), received high micromolar-millimolar levels of heme proportional to the number of units transfused, sufficient to overwhelm endogenous hemopexin levels early after TH and resuscitation. Limitations of the study include lack of assessment of temporal changes in different products of hemolysis after resuscitation and the small sample size precluding testing of associations between heme levels and adverse outcomes in resuscitated TH patients.

CONCLUSIONS

We provide evidence that large volume resuscitation with stored blood, compared to fresh blood, in mice increases mortality from subsequent pneumonia, which occurs via mechanisms sensitive to hemopexin and TLR4 and HMGB1 inhibition.

Red blood cells are dynamic reservoirs of cytokines

Red blood cells (RBCs) have been shown to affect immune function and can induce inflammatory responses after transfusion. The transfusion of washed RBCs can significantly reduce adverse effects, however, the soluble factors that may mediate these effects have not been identified. Previous studies have identified, but not quantified, a small number of chemokines associated with RBCs. We isolated RBCs from healthy volunteers and quantified of a panel of 48 cytokines, chemokines, and growth factors in the lysate, cytosol, and conditioned media of these cells using Luminex^® technology. This analysis revealed that, after correcting for white blood cell and platelet contamination, 46 cytokines were detected in RBC lysates, and the median concentration in RBCs was 12-fold higher than in the plasma. In addition, extensive washing of RBCs, such as that performed in proteomics analyses or prior to some RBC transfusions, significantly attenuated the release of six cytokines following incubation at 37 °C. This supports the hypothesis that, alongside its gas exchange function, RBCs play a role in cytokine signalling. This discovery may help supplement disease biomarker research and may shed light on adverse inflammatory processes that can follow RBC transfusion.

Red blood cells: The primary reservoir of macrophage migration inhibitory factor in whole blood

Red blood cells are widely accepted to be inert carriers of oxygen and haemoglobin, but there is growing evidence that they play a much more critical role in immune function. Macrophage migration inhibitory factor (MIF) is a key cytokine in disease with additional oxido-reductase activity, which aids in managing oxidative stress. Although two studies have reported the presence of MIF in red blood cells, no study has quantified the levels of this protein. In this study, freshly isolated plasma, platelets, leukocytes, and red blood cells from healthy individuals were collected and the concentration of MIF was determined using an enzyme linked immunosorbent assay. This analysis demonstrated that MIF in red blood cells was present at 25 µg per millilitre of whole blood, which is greater than99% of the total MIF and 1000-fold higher concentration than plasma. This result was supported by electrophoresis and Western blot analysis, which identified MIF in its monomer structural form following sample processing. Furthermore, by assessing the level of tautomerase activity in red blood cell fractions in the presence of a MIF inhibitor, it was determined that the red blood cell-derived MIF was also functionally active. Together, these findings have implications on the effect of haemolysis during sample preparation and provide some clue into the inflammatory processes that occur following haemolysis in vivo. These results support the hypothesis that red blood cells are a major reservoir of this inflammatory protein and may play a role in inflammation.

Hemolysis in In-Date RBC Concentrates

OBJECTIVES

Hemolysis is one of the most prominent changes that occur during the liquid storage of RBCs in additive solution (AS), but most studies have measured hemolysis only on day 42.

METHODS

Prestorage leukoreduced RBCs in AS-1 and AS-3 were studied, one group on day 42 and a second group between day 0 and day 40. Each product was sampled for direct measurement of supernatant hemoglobin and hematocrit.

RESULTS

Ninety day 42 and 218 day 7 to day 39 RBCs showed a mean ± SD supernatant hemoglobin of 75 ± 100 vs 25.5 ± 16 mg/dL respectively (P < .01). Supernatant hemoglobin correlated weakly with storage age (r = 0.2, P < .01) but more strongly with hematocrit (r = 0.4, P < .01).

CONCLUSIONS

There are minimal differences in supernatant hemoglobin until the final days of liquid storage when some high hematocrit RBCs show excessive hemolysis.

The role of NIGMS P50 sponsored team science in our understanding of multiple organ failure

The history of the National Institute of General Medical Sciences (NIGMS) Research Centers in Peri-operative Sciences (RCIPS) is the history of clinical, translational, and basic science research into the etiology and treatment of posttraumatic multiple organ failure (MOF). Born out of the activism of trauma and burn surgeons after the Viet Nam War, the P50 trauma research centers have been a nidus of research advances in the field and the training of future academic physician-scientists in the fields of trauma, burns, sepsis, and critical illness. For over 40 years, research conducted under the aegis of this funding program has led to numerous contributions at both the bedside and at the bench. In fact, it has been this requirement for team science with a clinician-scientist working closely with basic scientists from multiple disciplines that has led the RCIPS to its unrivaled success in the field. This review will briefly highlight some of the major accomplishments of the RCIPS program since its inception, how they have both led and evolved as the field moved steadily forward, and how they are responsible for much of our current understanding of the etiology and pathology of MOF. This review is not intended to be all encompassing nor a historical reference. Rather, it serves as recognition to the foresight and support of many past and present individuals at the NIGMS and at academic institutions who have understood the cost of critical illness and MOF to the individual and to society.

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).

Red blood cell storage in additive solution-7 preserves energy and redox metabolism: a metabolomics approach

BACKGROUND

Storage and transfusion of red blood cells (RBCs) has a huge medical and economic impact. Routine storage practices can be ameliorated through the implementation of novel additive solutions (ASs) that tackle the accumulation of biochemical and morphologic lesion during routine cold liquid storage in the blood bank, such as the recently introduced alkaline solution AS-7. Here we hypothesize that AS-7 might exert its beneficial effects through metabolic modulation during routine storage.

STUDY DESIGN AND METHODS

Apheresis RBCs were resuspended either in control AS-3 or experimental AS-7, before ultrahigh-performance liquid chromatography-mass spectrometry metabolomics analysis.

RESULTS

Unambiguous assignment and relative quantitation was achieved for 229 metabolites. AS-3 and AS-7 results in many similar metabolic trends over storage, with AS-7 RBCs being more metabolically active in the first storage week. AS-7 units had faster fueling of the pentose phosphate pathway, higher total glutathione pools, and increased flux through glycolysis as indicated by higher levels of pathway intermediates. Metabolite differences are especially observed at 7 days of storage, but were still maintained throughout 42 days.

CONCLUSION

AS-7 formulation (chloride free and bicarbonate loading) appears to improve energy and redox metabolism in stored RBCs in the early storage period, and the differences, though diminished, are still appreciable by Day 42. Energy metabolism and free fatty acids should be investigated as potentially important determinants for preservation of RBC structure and function. Future studies will be aimed at identifying metabolites that correlate with in vitro and in vivo circulation times.

Anemia and Transfusion in Critical Care

Objective:

The objective of this report is to review the physiology and management of anemia in critical care. Selected publications on physiology and transfusion related to anemia and critical care, including the modern randomized trials of conservative versus liberal transfusion policy, were used. Anemia is compensated and tolerated in most critically ill patients as long as oxygen delivery is at least twice oxygen consumption. There are risks to blood transfusion which can be minimized by blood banking practice. The availability of cultured red cells may allow correction of anemia without significant risk. The benefit of transfusion in anemia must be weighted against the risk in any specific patient.

Conclusion and Recommendation:

In a criticially ill patient, anemia should be managed to avoid oxygen supply dependency (oxygen delivery less than twice comsumption) and to maintain moderate oxygen delivery reserve (DO2/VO2 > 3).

Peroxiredoxin-2 recycling is inhibited during erythrocyte storage

AIMS

Transfusion with stored red blood cells (RBCs) is associated with increased morbidity and mortality. Peroxiredoxin-2 (Prx-2) is a primary RBC antioxidant that limits hydrogen peroxide (H2O2)-mediated toxicity. Whether Prx-2 activity is altered during RBC storage is not known.

RESULTS

Basal and H2O2-induced Prx-2 activity was measured in RBCs (stored for 7-35 days). Basal Prx-2 thiol oxidation increased with RBC age, whereas H2O2-dependent formation of dimeric Prx-2 was similar. However, reduction of Prx-2 dimers to monomers became progressively slower with RBC storage, which was associated with increased H2O2-induced hemolysis. Surprisingly, no change in the NADPH-dependent thioredoxin (Trx)/Trx-reductase system, which recycles dimeric Prx-2, was observed in stored RBCs. Using mouse RBCs expressing human wild type (β93Cys) or hemoglobin (Hb) in which the conserved β93Cys residue is replaced by Ala (β93Ala), a role for this thiol in modulating Prx-2 reduction was demonstrated. Specifically, Prx-2 recycling was blunted in β93Ala RBC, which was reversed by carbon monoxide-treatment, suggesting that heme autoxidation-derived H2O2 maintains Prx-2 in the oxidized form in these cells. Moreover, assessment of the oxidative state of the β93Cys in RBCs during storage showed that while it remained reduced on intraerythrocytic Hb in stored RBC, it was oxidized to dehydroalanine on hemolyzed or extracellular Hb.

INNOVATION

A novel mechanism for regulated Prx-2 activity in RBC via the β93Cys residue is suggested.

CONCLUSION

These data highlight the potential for slower Prx-2 recycling and β93Cys oxidation in modulating storage-dependent damage of RBCs and in mediating post-transfusion toxicity.

Damage control resuscitation

The early recognition and management of hemorrhage shock are among the most difficult tasks challenging the clinician during primary assessment of the acutely bleeding patient. Often with little time, within a chaotic setting, and without sufficient clinical data, a decision must be reached to begin transfusion of blood components in massive amounts. The practice of massive transfusion has advanced considerably and is now a more complete and, arguably, more effective process. This new therapeutic paradigm, referred to as damage control resuscitation (DCR), differs considerably in many important respects from previous management strategies for catastrophic blood loss. We review several important elements of DCR including immediate correction of specific coagulopathies induced by hemorrhage and management of several extreme homeostatic imbalances that may appear in the aftermath of resuscitation. We also emphasize that the foremost objective in managing exsanguinating hemorrhage is always expedient and definitive control of the source of bleeding.

Routine storage of red blood cell (RBC) units in additive solution-3: a comprehensive investigation of the RBC metabolome

BACKGROUND

In most countries, red blood cells (RBCs) can be stored up to 42 days before transfusion. However, observational studies have suggested that storage duration might be associated with increased morbidity and mortality. While clinical trials are under way, impaired metabolism has been documented in RBCs stored in several additive solutions (ASs). Here we hypothesize that, despite reported beneficial effects, storage in AS-3 results in metabolic impairment weeks before the end of the unit shelf life.

STUDY DESIGN AND METHODS

Five leukofiltered AS-3 RBC units were sampled before, during, and after leukoreduction Day 0 and then assayed on a weekly basis from storage Day 1 through Day 42. RBC extracts and supernatants were assayed using a ultra-high-performance liquid chromatography separations coupled online with mass spectrometry detection metabolomics workflow.

RESULTS

Blood bank storage significantly affects metabolic profiles of RBC extracts and supernatants by Day 14. In addition to energy and redox metabolism impairment, intra- and extracellular accumulation of amino acids was observed proportionally to storage duration, suggesting a role for glutamine and serine metabolism in aging RBCs.

CONCLUSION

Metabolomics of stored RBCs could drive the introduction of alternative ASs to address some of the storage-dependent metabolic lesions herein reported, thereby increasing the quality of transfused RBCs and minimizing potential links to patient morbidity.

Red blood cell storage lesion

OBJECTIVE

To summarize current understanding of the mechanisms responsible for changes occurring during red blood cell (RBC) storage, collectively known as the storage lesion, and to review the biological and clinical consequences of increasing storage time of RBCs.

DATA SOURCES

Human and veterinary clinical studies, experimental animal model studies, and reviews of the RBC storage lesion with no date restrictions.

HUMAN DATA SYNTHESIS

Experimental studies have characterized the evolution of human RBC and supernatant changes that occur during storage and form the basis for concern about the potential for harm from long-term storage of RBCs. Although 4 randomized controlled trials of varying sizes failed to find an association between RBC storage time and negative clinical outcomes, a recent meta-analysis and numerous observational clinical studies have demonstrated that transfusion of old versus fresh stored RBCs is associated with an increased risk of morbidity and mortality, particularly among trauma victims and cardiac surgery patients. Potential clinical consequences of RBC transfusion following development of the storage lesion include risk of organ dysfunction, organ failure, infections, and death.

VETERINARY DATA SYNTHESIS

Experimental animal models have contributed to the evidence supporting adverse consequences of the RBC storage lesion. Studies on relevant RBC storage issues such as the effect of different preservative solutions and leukoreduction have been completed. Transfusion with RBCs stored for 42 days increases mortality in dogs with experimental sepsis.

CONCLUSION

Storage of RBCs induces progressive biochemical, biomechanical, and immunologic changes that affect red cell viability, deformability, oxygen carrying capacity, microcirculatory flow, and recipient response. Most reports in the human and veterinary literature support the concept that there are deleterious effects of the RBC storage lesion, but additional studies with improved experimental design are needed to identify compelling reasons to modify current blood banking and transfusion practices.

Factors affecting on serum lactate after cardiac surgery

BACKGROUND

The relation between elevated blood lactate level and mortality and morbidity rates after coronary bypass surgery is a proven subject. One of the factors that seems to affect directly the blood lactate level is the storage duration of packed red blood cells.

OBJECTIVES

This study aimed to evaluate the effect of storage duration of transfused blood on serum lactate during cardiac surgery and up to 24 hours after that in the ICU.

PATIENTS AND METHODS

In a cross-sectional study, 228 patients referred to three hospitals of Mashhad University of Medical Sciences for open cardiac surgery, was enrolled using systematic random sampling method. Immediately after accessing arterial line, the first sample of arterial blood gas (ABG) was obtained. For evaluation of lactate levels, the next samples were obtained at the end of surgery and after 24 hours of staying ICU.

RESULTS

Among 5 factors which affected lactate level during surgery, diabetes and higher ejection fraction (EF) reduced changes of the lactate level. On the other hand, the number of infused blood units, duration of on-pump time, and the mean storage duration of blood units were associated with elevated serum lactate during surgery. A significant relationship was found between blood storage duration and serum lactate levels 24 hours after surgery.

CONCLUSIONS

Comparing the serum lactate level before operation and 24 hours after the operation showed that the number of received blood units had a significant effect on serum lactate. We found no significant effect for blood storage duration; however, the number of given blood units was more significant.

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.

Transfusion begets anemia: the effect of aged blood on hematopoiesis

BACKGROUND

Following trauma, transfusion of aged stored blood is often necessary yet associated with increased morbidity and mortality. Despite blood replacement, many patients have a prolonged anemia requiring further transfusions. The effects of aged blood on bone marrow (BM) hematopoiesis have not been studied, and we hypothesized that stored blood suppresses BM function.

METHODS

Blood from Sprague-Dawley rats was stored for 1, 14, or 28 days with the industry preservative citrate-phosphate-dextrose-adenine-1 (CPDA-1). For in vitro studies, 5% supernatant was incubated with normal rat BM and cultured for erythroid (CFU-E) and granulocyte-macrophage (CFU-GM) colony-forming units. Data were compared with cultures of BM alone, 5% control plasma (negative control), and 12% CPDA-1. For in vivo studies, rats were transfused with stored supernatants (5% estimated blood volume (EBV) over 30 minutes). BM from each recipient was cultured for CFU-E and CFU-GM at 3 hours after transfusion. Data were compared with cultures of BM alone. Difference between groups determined by analysis of variance and Tukey's multiple comparison test.

RESULTS

In vitro exposure to CPDA-1, control plasma, or 1-day supernatant (D1) had no effect on BM growth compared with BM alone. In vitro exposure to 14-day (D14) and 28-day (D28) supernatant significantly suppressed CFU-E by 60% and CFU-GM growth by 71% (both p < 0.05) compared with D1 or medial alone. There were no differences between D14 and D28. In vivo exposure to D14 reduced BM CFU-E and CFU-GM growth by 55% (both p < 0.05) compared with D1 supernatant.

CONCLUSION

Plasma from aged blood adversely affects CFU-E and CFU-GM growth in rats. The effect is not mediated by CPDA-1. Transfusion of aged stored blood may contribute to BM dysfunction in critically ill patients, resulting in persistent anemia and the need for further transfusion. This BM dysfunction may also partly explain the observed increased susceptibility to infection.

Does non-transferrin bound iron contribute to transfusion related immune-modulation in preterms?

OBJECTIVE

There is increasing awareness that allogeneic transfusion is potentially harmful in preterm neonates secondary to transfusion related immunomodulation (TRIM). Non-transferrin bound iron (NTBI) may contribute to TRIM by promoting oxidative damage and pro-inflammatory cytokine release. The current study aimed to determine if transfusion early in the neonatal period resulted in an increase in circulating NTBI, oxidative stress and immune activation.

DESIGN

Prospective observational study.

SETTING

One transfusion event was studied in infants ≤28 weeks gestation between 2 and 6 weeks postnatal age (n=33) admitted to a tertiary neonatal intensive care unit.

METHODS

Serum NTBI, inflammatory cytokines and malondialdehyde (MDA) were measured from the donor pack, prior to and at 2-4 and 24 h post-transfusion.

RESULTS

Median (range) age at transfusion was 17 (14-39) days with the pretransfusion haemoglobin level 9.6 (7.4-10.4) g/dl. NTBI was detectable in 18 (51%) of the transfusion packs. NTBI levels were higher after transfusion (p<0.01) returning to pretransfusion levels by 24 h. Post-transfusion NTBI level correlated with the age of transfused blood (p<0.001) and was positively correlated with plasma MDA (p=0.01) but not IL-1β, IL-6, IL8 or TNFα.

CONCLUSIONS

Circulating NTBI is transiently elevated following blood transfusion in preterm newborns. This increase was related to the age of blood transfused and correlated with increases in oxidative stress but not pro-inflammatory cytokines. While further studies are necessary to determine whether these transient effects influence clinical outcome, the current data do not support a significant role in the very preterm neonate for NTBI in TRIM.

The effects of non-leukoreduced red blood cell transfusions on microcirculation in mixed surgical patients

BACKGROUND

The impact of the storage process on oxygen-carrying properties of red blood cells and the efficacy of red blood cell (RBC) transfusions concerning tissue oxygenation remain an issue of debate in transfusion medicine. Storage time and leukocyte content probably interact since longer storage duration is thought to cause greater accumulation of leukocyte-derived cytokines and red blood cell injury.

OBJECTIVES

The aim of this study was to investigate the effects of storage and the efficacy of fresh (stored for less than 1 week) versus aged (stored for more than 3 weeks) non-leukoreduced RBC transfusions on sublingual microvascular density and flow in mixed surgical patients.

METHODS

Eighteen surgical patients were included in this study. Patients were randomly assigned into two groups receiving fresh (Group A) and aged (Group B) RBC transfusions. Sublingual microcirculatory functional capillary density (FCD) and microvascular flow index (MFI) were assessed using orthogonal polarization spectral (OPS) imaging. Measurements and collection of blood samples were performed after induction of general anesthesia, before RBC transfusion and 30 min after the RBC transfusion ended.

RESULTS

In both groups RBC transfusions caused an increase in hemoglobin concentration (p<0.001). RBC transfusions increased FCD in Group A (p<0.001), while FCD remained unaffected in Group B. Changes in MFI following RBC transfusion in both groups remained unaltered.

CONCLUSIONS

Fresh non-leukoreduced RBC transfusions but not RBCs stored for more than 3weeks, were effective in improving microciruculatory perfusion by elevating the number of perfused microvessels in mixed surgical patients.

Plasma cytokines and markers of endothelial activation increase after packed red blood cell transfusion in the preterm infant

BACKGROUND

Transfusion of packed red blood cells (PRBCs) saves lives in the neonatal critical care setting and is one of the most common interventions in the preterm infant. The number and volume of PRBC transfusions are associated with several major neonatal morbidities, although a direct causal link between transfusion and major neonatal morbidity is still to be proven. Transfusion-related immunomodulation (TRIM) may underlie these adverse outcomes, yet it has received little attention in the high-risk preterm infant.

METHODS

One transfusion event was studied in infants ≤28 wk gestation between 2 and 6 wk postnatal age (n = 28). Plasma inflammatory cytokines and markers of endothelial activation were measured in the infants before and 2-4 h after transfusion, as well as in the donor pack.

RESULTS

Median (range) age at transfusion was 18 (14-39) days with the pretransfusion hemoglobin level at 9.8 (7.4-10.2) g/dl. Interleukin (IL)-1β (P = 0.01), IL-8 (P = <0.001), tumor necrosis factor-α (P = 0.008), and monocyte chemoattractant protein (P = 0.01) were increased after transfusion. A similar elevation in markers of endothelial activation was seen after transfusion with increased plasma macrophage inhibitory factor (P = 0.005) and soluble intracellular adhesion molecule-1 (P = <0.001).

CONCLUSION

Production of inflammatory cytokines and immunoactivation of the endothelium observed after the transfusion of PRBCs in the preterm infant may be a manifestation of TRIM. The implications of this emerging phenomenon within the preterm neonatal population warrant further investigation.

Erythrocyte storage increases rates of NO and nitrite scavenging: implications for transfusion-related toxicity

Storage of erythrocytes in blood banks is associated with biochemical and morphological changes to RBCs (red blood cells). It has been suggested that these changes have potential negative clinical effects characterized by inflammation and microcirculatory dysfunction which add to other transfusion-related toxicities. However, the mechanisms linking RBC storage and toxicity remain unclear. In the present study we tested the hypothesis that storage of leucodepleted RBCs results in cells that inhibit NO (nitric oxide) signalling more so than younger cells. Using competition kinetic analyses and protocols that minimized contributions from haemolysis or microparticles, our data indicate that the consumption rates of NO increased ~40-fold and NO-dependent vasodilation was inhibited 2-4-fold comparing 42-day-old with 0-day-old RBCs. These results are probably due to the formation of smaller RBCs with increased surface area: volume as a consequence of membrane loss during storage. The potential for older RBCs to affect NO formation via deoxygenated RBC-mediated nitrite reduction was also tested. RBC storage did not affect deoxygenated RBC-dependent stimulation of nitrite-induced vasodilation. However, stored RBCs did increase the rates of nitrite oxidation to nitrate in vitro. Significant loss of whole-blood nitrite was also observed in stable trauma patients after transfusion with 1 RBC unit, with the decrease in nitrite occurring after transfusion with RBCs stored for >25 days, but not with younger RBCs. Collectively, these data suggest that increased rates of reactions between intact RBCs and NO and nitrite may contribute to mechanisms that lead to storage-lesion-related transfusion risk.

Washing of banked blood by three different blood salvage devices

BACKGROUND

Storage lesions in red blood cells (RBCs) lead to an accumulation of soluble contaminants that can compromise the patient. Organ failures, coagulopathies, and cardiovascular events including lethal cardiac arrest have been reported, especially with massive transfusion or in pediatric patients. Washing improves the quality of stored RBCs, and autotransfusion devices have been proposed for intraoperative processing, but these devices were designed for diluted wound blood, and limited data on their performance with RBCs are available.

STUDY DESIGN AND METHODS

Three autotransfusion devices (Electa, Sorin; CATS, Fresenius; OrthoPAT, Haemonetics) differing in function of their centrifugation chambers were evaluated with RBCs at the end of their shelf life and with dilutions thereof. Elimination rates of potassium, plasma free hemoglobin, total protein, citrate, acid equivalents, and iomeprol added as a marker substance were analyzed, in addition to RBC recoveries.

RESULTS

Product hematocrit (Hct) levels ranged between 54.8 and 72.6%. RBC recovery rates were between 62.7 and 95.0%, the lowest being with the OrthoPAT processing of undiluted RBCs. Plasma elimination rates increased with predilution and ranged from 46.6% to 99.5%, the lowest being with the CATS and undiluted RBCs. Washing did not change pH and buffering capacity of RBCs.

CONCLUSION

Autotransfusion devices offer a practical and obviously economical option to wash banked RBCs intraoperatively to prevent hyperkalemia and other disturbances in massive transfusion or pediatric patients. Predilution improves elimination rates, especially in devices that produce high product Hct levels. With a Y-tubing the RBCs should bypass reservoir and vacuum, and the procedure should be guarded by a policy and procedure manual and a quality management system.

Effect of processing and storage on red blood cell function in vivo

Red blood cell (RBC) transfusion is indicated to improve oxygen delivery to tissue, and for no other purpose. We have come to appreciate that donor RBCs are fundamentally altered during processing and storage in a manner that both impairs oxygen transport efficacy and introduces additional risk by perturbing both immune and coagulation systems. The protean biophysical and physiological changes in RBC function arising from storage are termed the "storage lesion;" many have been understood for some time; for example, we know that the oxygen affinity of stored blood rises during the storage period and that intracellular allosteric regulators, notably 2,3-bisphosphoglyceric acid and ATP, are depleted during storage. Our appreciation of other storage lesion features has emerged with improved understanding of coagulation, immune, and vascular signaling systems. Here, we review key features of the "storage lesion." Additionally, we call particular attention to the newly appreciated role of RBCs in regulating linkage between regional blood flow and regional O(2) consumption by regulating the bioavailability of key vasoactive mediators in plasma, and discuss how processing and storage disturb this key signaling function and impair transfusion efficacy.

Immune safety evaluation of polymerized porcine hemoglobin (pPolyHb): a potential red blood cell substitute

Polymerized Porcine Hemoglobin (pPolyHb), a hemoglobin-based oxygen carrier (HBOC), was developed as a potential red blood substitute for clinical applications. Assessment of its effects on the immune system is an important component of the overall safety evaluation of HBOC. For this purpose, we assessed three inflammation indicators, including complement C3a, IL-6, and TNF-? in cultured cells and in a rat model when pPolyHb was incubated or administrated with the cells/animals. Our results suggested that the levels of these three indicators were not statistically changed upon pPolyHb stimulation, indicating that pPolyHb is not immunotoxic to cells and animals in this aspect.

Accumulation of pro-cancer cytokines in the plasma fraction of stored packed red cells

INTRODUCTION

Perioperative blood transfusion has been linked to decreased survival in pancreatic cancer; however, the exact causal mechanism has not been elucidated. Allogeneic transfusions are known to expose patients to foreign cells and lipid mediators. We hypothesize that stored packed red cells (pRBCs) contain pro-cancer cytokines that augment tumor progression. We analyzed the plasma fraction of stored pRBCs for pro-cancer cytokines and evaluated the affect of both storage time and leukocyte reduction on these mediators.

METHODS

Chemiarray™ analysis for pro-cancer cytokines was performed on the acellular plasma fraction of stored leukocyte-reduced (LR) and non-leukocyte-reduced (NLR) pRBCs at day 1 (D.1-fresh) and day 42 (D.42-outdate) of storage. Elevated expression of monocyte chemotactic protein-1 (MCP-1), regulated on activation, normal T cell expressed and secreted (RANTES), angiogenin, tumor necrosis factor-alpha (TNF-α), epidermal growth factor (EGF), and platelet-derived growth factor (PDGF) was found. Specific enzyme-linked immunosorbent assay was performed for each of these factors in LR and NLR blood at D.1, day 28, and D.42. Data were analyzed by ANOVA. A p value ≤ 0.05 was considered significant; N ≥ 4 per group. Migration assays were performed using inhibitors of EGF (gefitinib) and PDGF (imatinib) on murine pancreatic adenocarcinoma cells (Pan02) exposed to D.1 and D.42 LR and NLR plasma. Proliferation assays were performed on Pan02 cells to test the inhibition of PDGF.

RESULTS

MCP-1 levels increased with storage time in LR blood, 86.3 ± 6.3 pg/ml at D.1 vs. 121.2 ± 6.1 pg/ml at D.42 (p = 0.007), and NLR blood, 78.2 ± 7.3 pg/ml at D.1 vs. 647.8 ± 220.7 pg/ml at D.42 (p = 0.02). RANTES levels are lower in LR compared to NLR stored blood, 3.0 ± 1.9 vs. 15.8 ± 0.7 pg/ml at D.42 (p < 0.001), but similar in D.1 blood, 13.8 ± 1.8 pg/ml in LR vs. 12.0 ± 1.6 pg/ml in NLR. Angiogenin levels were different between LR and NLR blood, 0 pg/ml (undetectable) vs. 44.2 ± 3.7 pg/ml (p < 0.001). Storage time did not affect concentration. TNF-α levels were not different between LR and NLR blood, and there was no storage time effect on concentration. EGF and PDGF levels increased with storage time in NLR blood only, 216.4 ± 3.8 pg/ml at D.1 vs. 1,436.4 ± 238.6 pg/ml at D.42 for EGF (p = 0.001), and 61.6 ± 6.0 pg/ml at D.1 vs. 76.5 ± 1.7 pg/ml at D.42 (p = 0.003) for PDGF. Inhibition of EGF reduced migration in Pan02 cells treated with D.42 NLR blood, 245.9 ± 11.2 vs. 164.6 ± 10.6 cells/hpf (p < 0.001). Inhibition of PDGF had no effect on Pan02 migration and reduced cell proliferation in cells treated with D.42 NLR, 181.1 ± 1.5% over control vs. 157.5 ± 2.1% (p < 0.001).

CONCLUSION

Pro-cancer cytokines that can augment tumor progression were identified in pRBCs. Some of these factors are present in fresh blood. The soluble factors identified herein may represent possible therapeutic targets to offset negative effects of transfusion. These data stress the need for efforts in cancer patients to reduce transfusion requirements if needed.

Red blood cell age and potentiation of transfusion-related pathology in trauma patients

The specific negative clinical manifestations associated with the transfusion of stored red blood cells (RBCs) and the corresponding mechanisms responsible for such phenomena remain poorly defined. Our recent studies document that leukoreduced older RBC units potentiate transfusion-related toxicity in trauma patients. It is our hypothesis that the transfusion of relatively older blood impedes microvascular perfusion. The central mechanisms proposed to mediate this microcirculatory alteration include: 1) the loss of RBC-dependent control of nitric oxide-mediated homeostasis concerning vasodilation and 2) immune cell and complement activation. In this review, we outline the background for our hypothesis and detail our current investigations toward the understanding of this pathophysiology.

Stored red blood cell supernatant facilitates thrombin generation

BACKGROUND

Observational studies have reported that patients transfused with red blood cells (RBCs) have a worse clinical outcome than untransfused patients and that storage age of RBCs at the time of transfusion may be an independent predictor of this adverse clinical outcome.

STUDY DESIGN AND METHODS

Eight RBC concentrates in additive solution were studied over an 8-week storage period. The RBC supernatant was ultracentrifuged to concentrate microvesicles (RCMVs). RCMVs were studied by flow cytometry to identify phosphatidylserine (PS)-expressing RCMVs and in a thromboelastograph (TEG) using a modified assay to detect a thrombin facilitation effect.

RESULTS

For all products, the percentage of RCMVs that exhibited PS expression on Day 1 was 50 ± 13%, which increased with storage, and on Day 31 was 90 ± 4%. After 31 days, four of the eight products showed a thrombin facilitation effect as evidenced by a shortening of the TEG reaction (R) time of 1.3 ± 1.1 minutes, which persisted to Day 41. Data are the mean ± 1 SD. This TEG R shortening effect was neutralized by annexin V. No such effect was observed on, or before, Day 21.

CONCLUSIONS

Some stored RBCs release RCMVs, which express PS and are capable of facilitating thrombin generation in vitro. This provides a possible mechanism by which stored RBCs could promote adverse thrombotic or inflammatory effects.

Duration of red cell storage influences mortality after trauma

BACKGROUND

Although previous studies have identified an association between the transfusion of relatively older red blood cells (RBCs) (storage ≥ 14 days) and adverse outcomes, they are difficult to interpret because the majority of patients received a combination of old and fresh RBC units. To overcome this limitation, we compared in-hospital mortality among patients who received exclusively old versus fresh RBC units during the first 24 hours of hospitalization.

METHODS

Patients admitted to a Level I trauma center between January 2000 and May 2009 who received ≥ 1 unit of exclusively old (≥ 14 days) vs. fresh (< 14 days) RBCs during the first 24 hours of hospitalization were identified. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated for the association between mortality and RBC age, adjusted for patient age, Injury Severity Score, gender, receipt of fresh frozen plasma or platelets, RBC volume, brain injury, and injury mechanism (blunt or penetrating).

RESULTS

One thousand six hundred forty-seven patients met the study inclusion criteria. Among patients who were transfused 1 or 2 RBC units, no difference in mortality with respect to RBC age was identified (adjusted RR, 0.97; 95% CI, 0.72-1.32). Among patients who were transfused 3 or more RBC units, receipt of old versus fresh RBCs was associated with a significantly increased risk of mortality, with an adjusted RR of 1.57 (95% CI, 1.14-2.15). No difference was observed concerning the mean number of old versus fresh units transfused to patients who received 3 or more units (6.05 vs. 5.47, respectively; p = 0.11).

CONCLUSION

In trauma patients undergoing transfusion of 3 or more RBC units within 24 hour of hospital arrival, receipt of relatively older blood was associated with a significantly increased mortality risk. Reservation of relatively fresh RBC units for the acutely injured may be advisable.

Association between length of storage of transfused red blood cells and multiple organ dysfunction syndrome in pediatric intensive care patients

BACKGROUND

The objective was to determine if there is an association between red blood cell (RBC) storage time and development of new or progressive multiple organ dysfunction syndrome (MODS) in critically ill children.

STUDY DESIGN AND METHODS

This was an analytic cohort analysis of patients enrolled in a randomized controlled trial, TRIPICU (Transfusion Requirements in Pediatric Intensive Care Units; ISRCTN37246456), in which stable critically ill children were randomly assigned to a restrictive or liberal strategy. Transfused patients were analyzed using three different sliding time cutoffs (7, 14, and 21 days). Storage time for multiply transfused patients was defined according to the oldest unit transfused.

RESULTS

A total of 455 patients were retained (liberal, 310; restrictive, 145). Multivariate logistic regression was performed to determine independent associations. In the restrictive group, a maximum RBC storage time of more than 21 days was independently associated with new or progressive MODS (adjusted odds ratio [OR], 3.29; 95% confidence interval [CI], 1.21-9.04). The same association was found in the liberal group for a storage time of more than 14 days (adjusted OR, 2.50; 95% CI, 1.12-5.58). When the two groups were combined in a meta-analysis, a storage time of more than 14 days was independently associated with increased MODS (adjusted OR, 2.23; 95% CI, 1.20-4.15) and more than 21 days was associated with increased Pediatric Logistic Organ Dysfunction (PELOD) scores (adjusted mean difference, 4.26; 95% CI, 1.99-6.53) and higher mortality (9.2% vs. 3.8%).

CONCLUSION

Stable critically ill children who receive RBC units with storage times longer than 2 to 3 weeks may be at greater risk of developing new or progressive MODS.

Platelet-white blood cell (WBC) interaction, WBC apoptosis, and procoagulant activity in stored red blood cells

BACKGROUND

Nonleukoreduced units of red blood cells (RBCs) contain activated platelets (PLTs) that interact with white blood cells (WBCs) and may promote inflammation and thrombosis in the recipient. The aim of this study was to characterize PLT-WBC interactions (PLT-WBC aggregates [PLAs]), WBC apoptosis, WBC death, and the development of procoagulant activity in RBCs during storage.

STUDY DESIGN AND METHODS

RBCs were prepared from volunteer donor blood and stored. Samples were analyzed with flow cytometry between Days 1 and 15 to measure PLT-monocyte aggregate (PMA) and PLT-neutrophil aggregate (PNA) formation, WBC apoptosis (annexin V binding), and cell death (binding of 7-aminoactinomycin D). Procoagulant activity in the supernatant of four RBC preparations was assessed between Days 1 and 39 using a clotting assay with and without the addition of an inhibitory anti-tissue factor (TF) antibody, αTF-5.

RESULTS

PLA formation was extensive and maximal on Day 3 of storage (PNA, 23 ± 13%; PMA, 93 ± 4%; n = 6). Apoptosis was progressive throughout storage, with 95 ± 4% of neutrophils and 73 ± 19% of monocytes binding annexin V on Day 15. Cell death became measurable after apoptosis. Procoagulant activity was observed in all RBCs but with varying temporal patterns. It was partially TF dependent and removed with high-speed centrifugation, suggestive of an association with microparticles.

CONCLUSION

The activation of PLTs during the storage of RBCs induces PLA formation that precedes WBC apoptosis and death. Procoagulant activity, likely associated with microparticles derived from apoptotic WBCs, may contribute to adverse effects of stored, nonleukoreduced RBCs.

Transfusion-free neonatal cardiopulmonary bypass using a TinyPump

BACKGROUND

We devised a miniaturized circuit incorporating a TinyPump in the venous line to amplify the venous return. We compared this system to the conventional blood-primed circuit and investigated whether this circuit could maintain hematocrit levels without blood transfusion and reduce coagulation and inflammatory cascades.

METHODS

Thirteen 1-week-old piglets (3.7 ± 0.2 kg) were divided into group M (miniaturized circuits with TinyPump-assisted venous drainage without blood, n = 7) and group C (conventional circuits with blood priming, n = 6). Cardiopulmonary bypass (CPB) was performed at 150 to 180 mL·kg(-1)·min(-1) for 2 hours, including 60 minutes of cardioplegic cardiac arrest. Modified ultrafiltration (MUF) was subsequently performed. Data were acquired before CPB and after the end of MUF.

RESULTS

The priming volume including the hemofilter circuit of the main circuit required 152 mL in group M and 300 mL in group C. The mean hematocrit values in group M and group C were not significantly different during CPB (21.5% ± 2.0% versus 23.2% ± 1.3%) or after MUF (30.7% ± 2.1% versus 32.9% ± 4.0%). After MUF, group M had lower thrombin-antithrombin complex levels (16.7 ± 5.0 ng/mL versus 28.4 ± 8.4 ng/mL, p < 0.01) and interleukin-8 levels (2,867 ± 758 pg/mL versus 13,730 ± 5,220 pg/mL, p < 0.01) than group C. The pulmonary vascular resistance index was lower in group M after MUF (4,105 ± 862 dynes·cm(-5)·kg(-1) versus 6,304 ± 1,477 dynes·cm(-5)·kg(-1), p < 0.01). The lung water content was also better in group M (83.7% ± 0.5% versus 84.9% ± 0.5%, p < 0.01).

CONCLUSIONS

The minicircuit with TinyPump-assisted venous drainage successfully maintained acceptable hematocrit levels and the cardiopulmonary function in neonatal piglets. Employing this technique may attenuate blood requirements and inflammatory responses, thereby improving the clinical outcomes of neonatal open-heart surgery.

Intravenous delivery of the plasma fraction of stored packed erythrocytes promotes pancreatic cancer growth in immunocompetent mice

BACKGROUND

Perioperative blood transfusion in pancreatic cancer patients has been linked to decreased survival; however, a causal mechanism has not been determined. During the processing and storage of packed erythrocytes, biologically active molecules accumulated in the acellular plasma fraction; therefore, the authors hypothesized that the plasma fraction of stored packed erythrocytes promoted tumor progression.

METHODS

Proliferation and migration of murine pancreatic cancer and control cells were determined in vitro in response to the plasma fraction from leukocyte and nonleukocyte-reduced fresh versus stored packed erythrocytes. Last, an immunocompetent murine model was used to assess the effect of the plasma fraction of stored and processed packed erythrocytes on pancreatic cancer progression.

RESULTS

Incubation of pancreatic cancer cells with the plasma fraction of packed erythrocytes increased proliferation and migration. Intravenous delivery of the acellular plasma fraction to mice with pancreatic cancer significantly increased the tumor weight in both leukocyte-reduced and nonleukocyte-reduced packed-erythrocyte groups (P<.01), although tumor growth and morbidity were greatest in the nonleukocyte-reduced group.

CONCLUSIONS

The plasma fraction of stored packed erythrocytes promoted murine pancreatic cancer proliferation and migration in vitro and when administered intravenously, significantly augmented pancreatic cancer growth in immunocompetent mice.

Prestorage leukoreduction ameliorates the effects of aging on banked blood

BACKGROUND

Previous studies have demonstrated that the transfusion of older blood is independently associated with higher rates of infectious complications, multiple organ failure, and mortality. Putative mechanisms implicate leukocytes in stored blood that generate immunomodulatory mediators as the stored blood ages. The purpose of this retrospective cohort study was to describe the effect of prestorage leukoreduction (PS-LR) on the detrimental clinical effects of increasing age on blood products used in trauma patients.

METHODS

All patients receiving >or=6 units of packed red cells and surviving >or=48 hours since May 1999 when institutional universal PS-LR was begun were identified. Transfusion requirements, demographic data, and causes of death were collected. Blood bank records were reviewed to determine the age of each unit of blood transfused. Multivariate logistic regression was used to determine the relationship between the age of PS-LR transfused blood and mortality after adjusting for total transfusion requirement, patient age, Injury Severity Score, head Abbreviated Injury Score, mechanism of injury, and gender. A subgroup analysis was performed excluding those patients in whom care was withdrawn at 48 hours to 72 hours postinjury for brain death or neurologic devastation.

RESULTS

A total of 399 patients, receiving 6,603 units of blood, met inclusion criteria. Mortality analysis showed that increasing Injury Severity Score, patient age, head Abbreviated Injury Score, and number of units of packed red cells transfused were all independently associated with an increased risk of death. When mean age of blood was analyzed as a continuous variable, a significant reduction in the risk of death with increasing mean age of transfused PS-LR blood was noted (odds ratio [OR], 0.959; 95% confidence interval [CI], 0.924-0.996). Both of these findings persisted when the mean age of blood was dichotomized at 14 days (OR, 0.426; 95% CI, 0.182-0.998) and 21 days (OR, 0.439; 95% CI, 0.225-0.857). The area under the curve for the receiver operating characteristics of our mortality model was 0.90. After excluding 13 patients in whom care was withdrawn 48 hours to 72 hours postinjury for brain death or neurologic devastation, the mortality analysis still showed that increasing injury severity, number of units of packed red cells transfused, and age were all independently associated with an increased risk of death. The protective effect of receiving older blood seen in the all-cause mortality analysis disappeared because no association was found between odds of dying and increasing age of packed red blood cells units transfused. This was true whether the mean age of transfused blood was dichotomized at 14 days (OR, 0.93; CI, 0.30-2.83) or at 21 days (OR, 0.54; CI, 0.25-1.16).

CONCLUSION

Our data suggest that the deleterious effects of aging on banked blood are ameliorated by PS-LR. We are currently conducting a prospective observational study in an effort to duplicate the findings of this retrospective investigation.

Perioperative blood transfusions promote pancreas cancer progression

Complex abdominal procedures to extirpate malignancies are often associated with blood transfusion. In particular, perioperative transfusion rates for pancreaticoduodenectomy can be as high as 75%. In the early 1970s it was shown that blood transfusions likely had immunomodulating effects as renal allografts were found to have longer survival in patients who received multiple transfusions. Subsequently, it has been suggested that blood transfusions may promote cancer progression. Many retrospective series have supported this hypothesis, and recent studies examining long-term survival in patients undergoing "Whipple" procedures suggests that transfusion is a negative prognostic factor. Despite these studies, the claim that transfusion is a simple surrogate for patient health, tumor size, location, and biology are difficult to refute. The use of syngeneic murine models has allowed many confounding variables to be controlled, and suggest that transfusion does indeed promote pancreas cancer progression. Based on these findings, as well as the continued need for blood transfusion, alternate strategies in transfusion management are warranted.

Complications of massive transfusion

Massive transfusion (MT) is a lifesaving treatment of hemorrhagic shock, but can be associated with significant complications. The lethal triad of acidosis, hypothermia, and coagulopathy associated with MT is associated with a high mortality rate. Other complications include hypothermia, acid/base derangements, electrolyte abnormalities (hypocalcemia, hypomagnesemia, hypokalemia, hyperkalemia), citrate toxicity, and transfusion-associated acute lung injury. Blood transfusion in trauma, surgery, and critical care has been identified as an independent predictor of multiple organ failure, systemic inflammatory response syndrome, increased infection, and increased mortality in multiple studies. Once definitive control of hemorrhage has been established, a restrictive approach to blood transfusion should be implemented to minimize further complications.

The role of neutrophils in the pathogenesis of transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is the major cause of transfusion related morbidity and mortality, world wide. Efforts to reduce or eliminate this serious complication of blood transfusion are hampered by an incomplete understanding of its pathogenesis. Currently, TRALI is thought to be mediated by donor alloantibodies directed against host leukocytes or the result of 2 distinct clinical events. For both proposed mechanisms, the neutrophil is the key effector cell. This article reviews TRALI pathophysiology, explores the role of the neutrophil, details practical information for appropriate diagnosis and promotes further studies into the pathogenesis of TRALI.