Relationship between red cell storage duration and outcomes in adults receiving red cell transfusions: a systematic review

Analysis of the incidence and risk factors of blood transfusion in total knee revision: a retrospective nationwide inpatient sample database study

OBJECTIVE

This study sought to determine the incidence and risk factors of blood transfusion among patients undergoing total knee revision (TKR) using a nationwide database.

METHODS

A retrospective data analysis was conducted based on the Nationwide Inpatient Sample (NIS), enrolling patients who underwent TKR from 2010 to 2019 with complete information. The patients were divided into two groups based on whether they received blood transfusion or not. The demographic characteristics (race, sex, and age), length of stay (LOS), total charge of hospitalization, hospital characteristics (admission type, insurance type, bed size, teaching status, location, and region of hospital), hospital mortality, comorbidities, and perioperative complications were analyzed. Finally, we conducted univariate and multivariate logistic regression to identify factors that were associated with TKR patients to require blood transfusion.

RESULTS

The NIS database included 115,072 patients who underwent TKR. Among them, 14,899 patients received blood transfusion, and the incidence of blood transfusion was 13.0%. There was a dramatic decrease in the incidence over the years from 2010 to 2019, dropping from 20.4 to 6.5%. TKR patients requiring transfusions had experienced longer LOS, incurred higher total medical expenses, utilized Medicare more frequently, and had increased in-hospital mortality rates (all P < 0.001). Independent predictors for blood transfusion included advanced age, female gender, iron-deficiency anemia, rheumatoid disease, chronic blood loss anemia, congestive heart failure, coagulopathy, uncomplicated diabetes, lymphoma, fluid and electrolyte disorders, metastatic carcinoma, other neurological diseases, paralysis, peripheral vascular disorders, pulmonary circulation disorders, renal failure, valvular disease, and weight loss. In addition, risk factors for transfusion in TKR surgery included sepsis, acute myocardial infarction, deep vein thrombosis, pulmonary embolism, gastrointestinal bleeding, heart failure, renal insufficiency, pneumonia, wound infection, lower limb nerve injury, hemorrhage/seroma/hematoma, wound rupture/non healing, urinary tract infection, acute renal failure, and postoperative delirium.

CONCLUSIONS

Our findings highlight the importance of recognizing the risk factors of blood transfusion in TKR to reduce the occurrence of adverse events.

Potential Predictors for Deterioration of Renal Function After Transfusion

BACKGROUND

Transfusion of packed red blood cells (pRBCs) is still associated with risks. This study aims to determine whether renal function deterioration in the context of individual transfusions in individual patients can be predicted using machine learning. Recipient and donor characteristics linked to increased risk are identified.

METHODS

This study was registered at ClinicalTrials.gov (NCT05466370) and was conducted after local ethics committee approval. We evaluated 3366 transfusion episodes from a university hospital between October 31, 2016, and August 31, 2020. Random forest models were tuned and trained via Python auto-sklearn package to predict acute kidney injury (AKI). The models included recipients' and donors' demographic parameters and laboratory values, donor questionnaire results, and the age of the pRBCs. Bootstrapping on the test dataset was used to calculate the means and standard deviations of various performance metrics.

RESULTS

AKI as defined by a modified Kidney Disease Improving Global Outcomes (KDIGO) criterion developed after 17.4% transfusion episodes (base rate). AKI could be predicted with an area under the curve of the receiver operating characteristic (AUC-ROC) of 0.73 ± 0.02. The negative (NPV) and positive (PPV) predictive values were 0.90 ± 0.02 and 0.32 ± 0.03, respectively. Feature importance and relative risk analyses revealed that donor features were far less important than recipient features for predicting posttransfusion AKI.

CONCLUSIONS

Surprisingly, only the recipients' characteristics played a decisive role in AKI prediction. Based on this result, we speculate that the selection of a specific pRBC may have less influence than recipient characteristics.

Transfused Red Blood Cell Characteristics and Kidney Transplant Outcomes Among Patients Receiving Early Posttransplant Transfusion

Importance

Red blood cell transfusion (RBCT) is frequently required in the early post-kidney transplant period, but long-term outcomes associated with RBCT is controversial. Therefore, it may be relevant to investigate the association between RBCT characteristics and transplant outcomes.

Objective

To study the association between RBC storage duration and transplant outcomes.

Design, Setting, and Participants

This was a nationwide retrospective cohort study based on data linking between 2 prospective French nationwide registries. Clinical transplant parameters, outcomes, and RBCT characteristics were extracted from the CRISTAL registry of the Agence de la Biomédecine and the national database of the Etablissement Français du Sang. All 12 559 patients having received a first kidney transplant in France between January 1, 2002, and December 31, 2008, were included. Patients were followed up from transplant to graft loss, death with a functional graft, or data retrieval in June 2016. Data were analyzed from April 2019 to June 2022.

Exposures

Clinical outcomes of transplant recipients who underwent early RBCT were analyzed considering transfusion characteristics.

Main Outcomes and Measures

Cox proportional hazards regression models were fitted to evaluate transplant failure defined as graft loss or death with a functional graft.

Results

Among 12 559 patients who underwent kidney transplant, 3483 received an RBCT during the first 14 days posttransplant. The median (IQR) age of patients was 53.0 (41.5-61.2) years, and 1929 patients (55.4%) were male. Median (IQR) follow-up was 7.8 (7.6-8.0) years. In multivariable analysis, longer (vs shorter) storage duration of transfused RBC was associated with a decrease in risk of transplant failure (hazard ratio, 0.99; 95% CI, 0.98-1.00 for each additional storage day; P = .06). Patients transfused with at least 1 RBC unit stored for more than 20 days had a 5% absolute decrease in transplant failure at 3 years and 7% at 5 years compared with those who received RBC stored for less than 20 days.

Conclusions and Relevance

In this study, longer RBC storage duration was associated with a decreased risk of transplant failure among patients who received kidney transplants and RBC transfusions. Preferential use of RBC with longer storage duration might improve kidney graft survival following transplant and transfusion.

Variability of extracellular vesicle release during storage of red blood cell concentrates is associated with differential membrane alterations, including loss of cholesterol-enriched domains

Transfusion of red blood cell concentrates is the most common medical procedure to treat anaemia. However, their storage is associated with development of storage lesions, including the release of extracellular vesicles. These vesicles affect in vivo viability and functionality of transfused red blood cells and appear responsible for adverse post-transfusional complications. However, the biogenesis and release mechanisms are not fully understood. We here addressed this issue by comparing the kinetics and extents of extracellular vesicle release as well as red blood cell metabolic, oxidative and membrane alterations upon storage in 38 concentrates. We showed that extracellular vesicle abundance increased exponentially during storage. The 38 concentrates contained on average 7 × 1012 extracellular vesicles at 6 weeks (w) but displayed a ∼40-fold variability. These concentrates were subsequently classified into 3 cohorts based on their vesiculation rate. The variability in extracellular vesicle release was not associated with a differential red blood cell ATP content or with increased oxidative stress (in the form of reactive oxygen species, methaemoglobin and band3 integrity) but rather with red blood cell membrane modifications, i.e., cytoskeleton membrane occupancy, lateral heterogeneity in lipid domains and transversal asymmetry. Indeed, no changes were noticed in the low vesiculation group until 6w while the medium and the high vesiculation groups exhibited a decrease in spectrin membrane occupancy between 3 and 6w and an increase of sphingomyelin-enriched domain abundance from 5w and of phosphatidylserine surface exposure from 8w. Moreover, each vesiculation group showed a decrease of cholesterol-enriched domains associated with a cholesterol content increase in extracellular vesicles but at different storage time points. This observation suggested that cholesterol-enriched domains could represent a starting point for vesiculation. Altogether, our data reveal for the first time that the differential extent of extracellular vesicle release in red blood cell concentrates did not simply result from preparation method, storage conditions or technical issues but was linked to membrane alterations.

Intermittent scavenging of storage lesion from stored red blood cells by electrospun nanofibrous sheets enhances their quality and shelf-life

Transfusion of healthy red blood cells (RBCs) is a lifesaving process. However, upon storing RBCs, a wide range of damage-associate molecular patterns (DAMPs), such as cell-free DNA, nucleosomes, free-hemoglobin, and poly-unsaturated-fatty-acids are generated. DAMPs can further damage RBCs; thus, the quality of stored RBCs declines during the storage and limits their shelf-life. Since these DAMPs consist of either positive or negative charged species, we developed taurine and acridine containing electrospun-nanofibrous-sheets (Tau-AcrNFS), featuring anionic, cationic charges and an DNA intercalating group on their surfaces. We show that Tau-AcrNFS are efficient in scavenging DAMPs from stored human and mice RBCs ex vivo. We find that intermittent scavenging of DAMPs by Tau-AcrNFS during the storage reduces the loss of RBC membrane integrity and reduces discocytes-to-spheroechinocytes transformation in stored-old-RBCs. We perform RBC-transfusion studies in mice to reveal that intermittent removal of DAMPs enhances the quality of stored-old-RBCs equivalent to freshly collected RBCs, and increases their shelf-life by ~22%. Such prophylactic technology may lead to the development of novel blood bags or medical device, and may therefore impact healthcare by reducing transfusion-related adverse effects.

A deep 96-well plate RBC storage platform for high-throughput screening of novel storage solutions

Background: Red blood cell (RBC) storage solutions, also known as additive solutions (ASs), first developed in the 1970s, enable extended storage of RBCs. Unfortunately, the advancements in this field have been limited, due to labor intensive and time-consuming serial in vitro and in vivo testing, coupled with very high commercialization hurdles. This study examines the utility of deep 96-well plates for preliminary screenings of novel ASs through comparison of RBC storage with the standard PVC bags in terms of hemolysis and ATP levels, under both normoxic (N) and hypoxic/hypocapnic (H) storage conditions. The necessity for the presence of DEHP, normally provided by PVC bags, is also examined. Materials and methods: A pool of 2 ABO compatible RBC units was split between a bag and a plate. Each plate well contained either 1, 2 or 0 PVC strips cut from standard storage bags to supply DEHP. The H bags and plates were processed in an anaerobic glovebox and stored in O2 barrier bags. Hemolysis and ATP were measured bi-weekly using standard methods. Results: Final ATP and hemolysis values for the plate-stored RBCs were comparable to the typical values observed for 6-week storage of leukoreduced AS-3 RBCs in PVC bags under both N and H conditions. Hemolysis was below FDA and EU benchmarks of 1% and 0.8%, respectively, and excluding DEHP from plates during storage, resulted in an inconsequential increase when compared to bag samples. Discussion: In combination with high-throughput metabolomics workflow, this platform provides a highly efficient preliminary screening platform to accelerate the initial testing and consequent development of novel RBC ASs.

Erysense, a Lab-on-a-Chip-Based Point-of-Care Device to Evaluate Red Blood Cell Flow Properties With Multiple Clinical Applications

In many medical disciplines, red blood cells are discovered to be biomarkers since they "experience" various conditions in basically all organs of the body. Classical examples are diabetes and hypercholesterolemia. However, recently the red blood cell distribution width (RDW), is often referred to, as an unspecific parameter/marker (e.g., for cardiac events or in oncological studies). The measurement of RDW requires venous blood samples to perform the complete blood cell count (CBC). Here, we introduce Erysense, a lab-on-a-chip-based point-of-care device, to evaluate red blood cell flow properties. The capillary chip technology in combination with algorithms based on artificial neural networks allows the detection of very subtle changes in the red blood cell morphology. This flow-based method closely resembles in vivo conditions and blood sample volumes in the sub-microliter range are sufficient. We provide clinical examples for potential applications of Erysense as a diagnostic tool [here: neuroacanthocytosis syndromes (NAS)] and as cellular quality control for red blood cells [here: hemodiafiltration (HDF) and erythrocyte concentrate (EC) storage]. Due to the wide range of the applicable flow velocities (0.1-10 mm/s) different mechanical properties of the red blood cells can be addressed with Erysense providing the opportunity for differential diagnosis/judgments. Due to these versatile properties, we anticipate the value of Erysense for further diagnostic, prognostic, and theragnostic applications including but not limited to diabetes, iron deficiency, COVID-19, rheumatism, various red blood cell disorders and anemia, as well as inflammation-based diseases including sepsis.

Storage-Induced Micro-Erythrocytes Can Be Quantified and Sorted by Flow Cytometry

Refrigerated storage of red cell concentrates before transfusion is associated with progressive alterations of red blood cells (RBC). Small RBC (type III echinocytes, sphero-echinocytes, and spherocytes) defined as storage-induced micro-erythrocytes (SME) appear during pretransfusion storage. SME accumulate with variable intensity from donor to donor, are cleared rapidly after transfusion, and their proportion correlates with transfusion recovery. They can be rapidly and objectively quantified using imaging flow cytometry (IFC). Quantifying SME using flow cytometry would further facilitate a physiologically relevant quality control of red cell concentrates. RBC stored in blood bank conditions were stained with a carboxyfluorescein succinimidyl ester (CFSE) dye and incubated at 37°C. CFSE intensity was assessed by flow cytometry and RBC morphology evaluated by IFC. We observed the accumulation of a CFSE ^high RBC subpopulation by flow cytometry that accounted for 3.3 and 47.2% at day 3 and 42 of storage, respectively. IFC brightfield images showed that this CFSE ^high subpopulation mostly contains SME while the CFSE ^low subpopulation mostly contains type I and II echinocytes and discocytes. Similar numbers of SME were quantified by IFC (based on projected surface area) and by flow cytometry (based on CFSE intensity). IFC and scanning electron microscopy showed that ≥95% pure subpopulations of CFSE ^high and CFSE ^low RBC were obtained by flow cytometry-based sorting. SME can now be quantified using a common fluorescent dye and a standard flow cytometer. The staining protocol enables specific sorting of SME, a useful tool to further characterize this RBC subpopulation targeted for premature clearance after transfusion.

Extracellular ubiquitin promotes hepatoma metastasis by mediating M2 macrophage polarization via the activation of the CXCR4/ERK signaling pathway

Background

Stored red blood cell (RBC) transfusion has been shown to enhance the risk of cancer recurrence. However, the underlying mechanism remains unknown. At our lab, we have demonstrated that the extracellular ubiquitin (eUb) released by aged RBCs could promote tumor metastasis in a melanoma mouse model. This study aimed to confirm the pro-tumor effect of eUb on hepatocellular carcinoma (HCC) and explore the related immunoregulatory mechanisms.

Methods

Forty HCC tissue specimens and the corresponding adjacent nontumor and normal liver tissues were collected. Two human hepatoma cell lines (MHCC-97H and HepG2.2.15), one murine hepatoma cell line (Hepa1-6), and one human monocyte cell line (THP-1) were adopted in this study. The coculture of hepatoma cells with macrophages was initiated with Transwell inserts. Cell migration in vitro was detected by Transwell and wound-healing assays, while in vivo tumor metastasis was measured by luciferase assay and H&E staining. Macrophage polarization was measured by flow cytometry, immunofluorescence, ELISA, qPCR, and Western blot. Protein expression was detected by Western blot, and immunoprecipitation was used to confirm the interaction between Ub and CXCR4 (CXC chemokine receptor type 4).

Results

Ub and CXCR4 were significantly upregulated in HCC tissues, and a positive correlation existed between them. In vitro, the migration of hepatoma cells was not affected by eUb directly, but their metastatic abilities were enhanced after coculture with the macrophages pretreated with eUb. Meanwhile, eUb promoted hepatoma cell metastasis in the lung in vivo and increased the ratio of M2 macrophages in the lung tissues and peripheral blood of tumor-bearing mice. Furthermore, the eUb-induced M2 macrophage polarization was related to the activation of the CXCR4/ERK (extracellular regulated protein kinase) signaling pathway.

Conclusions

Extracellular ubiquitin promoted hepatoma metastasis through M2 macrophage polarization via the activation of the CXCR4/ERK signaling pathway, indicating that a personalized transfusion strategy is needed for the treatment of HCC patients. Neutralizing Ub in stored RBC units could lessen the detrimental clinical outcomes induced by the transfusion of stored RBCs.

Pulmonary embolism associated with transfusion after severe post-partum haemorrhage: is less more?

BACKGROUND

Transfusion of red blood cells is associated with superficial vein thrombosis (SVT) and venous thromboembolism (deep vein thrombosis and/or pulmonary embolism, VTE). The present study investigated the prevalence of SVT and VTE in women transfused in the peri-partum period.

MATERIALS AND METHODS

We carried out an observational study in a tertiary level obstetrics department in the Apulia Region of Southern Italy to investigate VTE in women transfused during or after labour. The study included all women who delivered between January 1st and November 30th, 2018. A thrombotic event was defined as an admission with an ICD-9 code of SVT and VTE as a primary or secondary diagnosis. Maternal "near-miss" rate, as defined by the World Health Organization, was calculated and outcome of transfused women was recorded.

RESULTS

From January 1st to November 30th, a total of 1,028 women delivered, 39% of them by caesarean section (CS). One-hundred and thirty-two women (12.8%) had been classified with one or more complication codes. Most complications occurred in women who underwent CS with an odds ratio (OR) of 7.0 (95% CI: 4.0-12.5; p=0.000). Twelve women (1.2%) were transfused in the peri-partum period, 7 of them had delivered by CS. The only thrombotic events recorded in the entire cohort of 1,028 patients were isolated pulmonary embolisms observed in 2 out of 12 transfused women. Overall, patients had received a mean of 7.5 units of packed red blood cells (1 patient also received 7 plasma units, while 1 patient also received 1 platelet unit). Consequently, the near-miss rate was 2.0/1,000 deliveries, which is not significantly different from that expected in Italy and in high-income countries.

CONCLUSIONS

Pulmonary embolism is a life-threatening complication, which can be associated with transfusion in the peri-partum period.

Transfusion-related Acute Lung Injury in the Perioperative Patient

Transfusion-related acute lung injury is a leading cause of death associated with the use of blood products. Transfusion-related acute lung injury is a diagnosis of exclusion which can be difficult to identify during surgery amid the various physiologic and pathophysiologic changes associated with the perioperative period. As anesthesiologists supervise delivery of a large portion of inpatient prescribed blood products, and since the incidence of transfusion-related acute lung injury in the perioperative patient is higher than in nonsurgical patients, anesthesiologists need to consider transfusion-related acute lung injury in the perioperative setting, identify at-risk patients, recognize early signs of transfusion-related acute lung injury, and have established strategies for its prevention and treatment.

Extracellular Ubiquitin is the Causal Link between Stored Blood Transfusion Therapy and Tumor Progression in a Melanoma Mouse Model

Background: The transfusion of blood that has been stored for some time was found to be associated with transfusion-related immune modulation (TRIM) responses in cancer patients, which could result in poor clinical outcomes, such as tumor recurrence, metastasis and reduced survival rate. Given the prior observation of the positive correlation between ubiquitin content in whole blood and storage duration by the investigators of the present study, it was hypothesized that this could be the causal link behind the association between the transfusion of stored blood and poor cancer prognosis.

Methods: In the present study, a melanoma mouse model was used to study the potential clinical impact of ubiquitin present in stored blood on cancer prognosis through a variety of cell biology methods, such as flow cytometry and immunohistochemistry.

Results: Both extracellular ubiquitin and the infusion of stored mice blood that comprised of ubiquitin reduced the apoptotic rate of melanoma cells, promoted lung tumor metastasis and tumor progression, and reduced the long-term survival rate of melanoma mice. In addition, the upregulation of tumor markers and tumorigenic TH2 cytokine generation, as well as reduced immune cell numbers, were observed in the presence of ubiquitin.

Conclusions: The present findings provide novel insights into the role of ubiquitin in immune regulation in a melanoma mouse model, and suggest ubiquitin as the causal link between allogeneic blood transfusion therapy and poor cancer prognosis.

A longer duration of red blood cell storage is associated with a lower hemoglobin increase after blood transfusion: a cohort study

BACKGROUND

RBC concentrates are commonly stored for up to 42 days but there has been conflicting evidence on the effect of storage duration and clinical outcomes. Most clinical studies have focused on possible associations between duration of storage time and risk for adverse outcomes, including mortality. Recent clinical trials did not find any such associations, but fewer studies have addressed whether storage time affects component efficacy. The main aim of this study was to determine the effect of RBC storage time on hemoglobin increment in transfused patients.

STUDY DESIGN AND METHODS

Transfusion data on a cohort of patients with myelodysplastic syndromes were linked to hemoglobin measurements taken between 2 days before and 28 days after a transfusion episode. We applied a mixed-effect linear regression model, accounting for patient characteristics and time from transfusion to next hemoglobin measurement, to study the effect of RBC storage on the hemoglobin increment.

RESULTS

The study population consisted of 225 patients who received 6437 RBC units. Compared to units stored less than 5 days, transfusion of blood units stored 5 to 9, 10 to 19, 20 to 29, or 30 or more days resulted in hemoglobin increases that were 0.83 (95% confidence interval [CI], 0.24-1.41), 0.92 (95% CI, 0.34-1.51), 1.33 (95% CI, 0.65-2.02) and 1.51 (95% CI, 0.58-2.43) g/L lower, respectively, per RBC unit. Results were consistent in sensitivity analyses.

CONCLUSIONS

Longer RBC storage was associated with a smaller increase in hemoglobin concentration after transfusion. Although statistically significant, the effect was modest, and its clinical relevance in subgroups of patients should be investigated in prospective clinical trials.

Blood transfusions, blood storage, and correlation with elevated pulmonary arterial pressures

BACKGROUND

The aim of this study was to determine if transfusion with RBCs is associated with a rise in mean pulmonary artery pressure (MPAP) and whether such a rise is influenced by the duration of RBC storage.

STUDY DESIGN AND METHODS

A retrospective chart review of intensive care unit patients with pulmonary artery catheters was conducted at two military medical centers.

RESULTS

RBC transfusion is associated with a sustained (≥4 hours) statistically significant 2- to 3-mm Hg rise in MPAP relative to both pretransfusion levels (p < 0.05) and compared to asanguinous fluid infusions (p < 0.05). The magnitude of the rise (all infusions, RBCs, and asanguinous) correlates positively with in-hospital mortality (p < 0.01) and hospital length of stay (p < 0.01). The duration of RBC storage was not statistically correlated with the magnitude of rise in the population studied. Mean infusion volume was greater for RBC (vs. asanguinous) infusions, but volume adjustment of MPAP values did not alter the pattern or statistical significance of the results.

CONCLUSIONS

Analysis of retrospectively collected data suggests that transfusion of RBC-containing fluids results in a sustained elevation of MPAP. In the patient population studied, the duration of RBC storage did not correlate with the magnitude of MPAP rise. Future prospective studies of transfusion effects should consider including assessment of MPAP and subpopulation analyses.

Transfusion of red blood cells stored for shorter versus longer duration for all conditions

BACKGROUND

Red blood cell (RBC) transfusion is a common treatment for anaemia in many conditions. The safety and efficacy of transfusing RBC units that have been stored for different durations before a transfusion is a current concern. The duration of storage for a RBC unit can be up to 42 days. If evidence from randomised controlled trials (RCT) were to indicate that clinical outcomes are affected by storage duration, the implications for inventory management and clinical practice would be significant.

OBJECTIVES

To assess the effects of using red blood cells (RBCs) stored for a shorter versus a longer duration, or versus RBCs stored for standard practice duration, in people requiring a RBC transfusion.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, PubMed (for epublications), LILACS, Transfusion Evidence Library, Web of Science CPCI-S and four international clinical trial registries on 20 November 2017.

SELECTION CRITERIA

We included RCTs that compared transfusion of RBCs of shorter versus longer storage duration, or versus standard practice storage duration.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods.

MAIN RESULTS

We included 22 trials (42,835 participants) in this review.The GRADE quality of evidence ranged from very low to moderate for our primary outcome of in-hospital and short-term mortality reported at different time points.Transfusion of RBCs of shorter versus longer storage duration Eleven trials (2249 participants) compared transfusion of RBCs of shorter versus longer storage duration. Two trials enrolled low birth weight neonates, two enrolled children with severe anaemia secondary to malaria or sickle cell disease, and eight enrolled adults across a range of clinical settings (intensive care, cardiac surgery, major elective surgery, hospitalised in-patients, haematology outpatients). We judged only two trials to be at low risk of bias across all domains; most trials had an unclear risk for multiple domains.Transfusion of RBCs of shorter versus longer storage duration probably leads to little or no difference in mortality at seven-day follow-up (risk ratio (RR) 1.42, 95% confidence interval (CI) 0.66 to 3.06; 1 trial, 3098 participants; moderate quality evidence) or 30-day follow-up (RR 0.85, 95%CI 0.50 to 1.45; 2 trials, 1121 participants; moderate quality evidence) in adults undergoing major elective cardiac or non-cardiac surgery.For neonates, no studies reported on the primary outcome of in-hospital or short-term mortality. At 40 weeks gestational age, the effect of RBCs of shorter versus longer storage duration on the risk of death was uncertain, as the quality of evidence is very low (RR 0.90, 95% CI 0.41 to 1.85; 1 trial, 52 participants).The effect of RBCs of shorter versus longer storage duration on the risk of death in children with severe anaemia was also uncertain within 24 hours of transfusion (RR 1.50, 95% CI 0.43 to 5.25; 2 trials, 364 participants; very low quality evidence), or at 30-day follow-up (RR 1.40, 95% CI 0.45 to 4.31; 1 trial, 290 participants; low quality evidence).Only one trial, in children with severe anaemia (290 participants), reported adverse transfusion reactions. Only one child in each arm experienced an adverse reaction within 24 hours of transfusion.Transfusion of RBCs of shorter versus standard practice storage duration Eleven trials (40,588 participants) compared transfusion of RBCs of shorter versus standard practice storage duration. Three trials enrolled critically ill term neonates; two of these enrolled very low birth weight neonates. There were no trials in children. Eight trials enrolled critically ill and non-critically ill adults, with most being hospitalised. We judged four trials to be at low risk of bias across all domains with the others having an unclear risk of bias across multiple domains.Transfusion of RBCs of shorter versus standard practice storage duration probably leads to little or no difference in adult in-hospital mortality (RR 1.05, 95% CI 0.97 to 1.14; 4 trials, 25,704 participants; moderate quality evidence), ICU mortality (RR 1.06, 95% CI 0.98 to 1.15; 3 trials, 13,066 participants; moderate quality evidence), or 30-day mortality (RR 1.04, 95% CI 0.96 to 1.13; 4 trials, 7510 participants;moderate quality evidence).Two of the three trials that enrolled neonates reported that there were no adverse transfusion reactions. One trial reported an isolated case of cytomegalovirus infection in participants assigned to the standard practice storage duration group. Two trials in critically ill adults reported data on transfusion reactions: one observed no difference in acute transfusion reactions between arms (RR 0.67, 95% CI 0.19 to 2.36, 2413 participants), but the other observed more febrile nonhaemolytic reactions in the shorter storage duration arm (RR 1.48, 95% CI 1.13 to 1.95, 4919 participants).Trial sequential analysis showed that we may now have sufficient evidence to reject a 5% relative risk increase or decrease of death within 30 days when transfusing RBCs of shorter versus longer storage duration across all patient groups.

AUTHORS' CONCLUSIONS

The effect of storage duration on clinically important outcomes has now been investigated in large, high quality RCTs, predominantly in adults. There appears to be no evidence of an effect on mortality that is related to length of storage of transfused RBCs. However, the quality of evidence in neonates and children is low. The current practice in blood banks of using the oldest available RBCs can be continued safely. Additional RCTs are not required, but research using alternative study designs, should focus on particular subgroups (e.g. those requiring multiple RBC units) and on factors affecting RBC quality.

Longer storage of red blood cells does not affect mortality in transfused liver transplant recipients

BACKGROUND

The characteristics of red blood cell (RBC) products change after 2 weeks of cold storage. It is unclear whether older RBCs affect mortality after liver transplantation. This retrospective cohort study aimed to evaluate the association between the age of transfused RBCs and death after living donor liver transplantation (LDLT).

STUDY DESIGN AND METHODS

Of 200 recipients who underwent LDLT, 118 who received RBCs with a mean storage duration of less than 10 days (shorter storage group) were compared with 82 with an RBC mean storage duration of more than 14 days (longer storage group). Key exclusion criteria were transfusion of very fresh RBCs stored for less than 4 days and transfusion of old RBCs in recipients of the shorter storage group. The primary outcome was posttransplant overall death. Survival analysis was performed using the Cox model.

RESULTS

Mean RBC storage duration was 7 days in the shorter storage group and 17 days in the longer storage group. Death probability at 1, 2, and 5 years posttransplant was 5.1%, 7.6%, and 13.6% in the shorter storage group, respectively, and 6.1%, 8.5%, and 13.5% in the longer storage group. Death risk was comparable between the two groups in univariable (hazard ratio [HR] 1.00, 95% confidence interval [CI], 0.47-2.16, p = 0.991) and multivariable (HR 1.07, 95% CI, 0.46-2.50, p = 0.882) analyses. Graft failure risk was also comparable (HR 1.04, 95% CI, 0.50-2.18, p = 0.916). Hepatocellular carcinoma recurrence probability at 1, 2, and 5 years was 10.8%, 15.4%, and 23.1%, respectively, in the shorter storage group and 11.4%, 15.9%, and 20.7% in the longer storage group (HR 0.84, 95% CI, 0.37-1.89, p = 0.670). No significant differences were observed regarding graft regeneration/function, vascular/biliary complications, acute kidney injury, surgical site infection, or rejection (p > 0.05).

CONCLUSIONS

No evidence was found that transfusion of old RBCs contributes to death after LDLT.

Age of transfused red blood cells and health outcomes in two surgical cohorts

RATIONALE

Red blood cells (RBC) undergo morphologic and biochemical changes during storage which may lead to adverse health risks upon transfusion. In prior studies, the effect of RBC age on health outcomes has been conflicting. We designed the study to assess the effects of RBC units' storage duration on health outcomes specifically for hospitalized patients undergoing hip fracture surgery or coronary artery bypass grafting (CABG) surgery.

METHODS

Using International Classification of Diseases (ICD) 9 codes, hip fracture surgery and CABG surgery patients, who received RBC transfusions between 2008 and 2013, were retrospectively identified from the electronic medical records system. Hip fracture surgery and CABG cohorts were sub-divided into 3 blood age groups based upon RBC unit age at the time of transfusion: young blood (RBC units stored less than or equal to 14 days), old blood (RBC units were stored for greater than or equal to 28 days), or mixed blood for the remaining patients. Outcome variables were 30-day, 90-day, and inpatient mortality as well as hospital length of stay.

RESULTS

A total of 3,182 patients were identified: 1,121 with hip fractures and 2,061 with CABG. Transfusion of old blood was associated with higher inpatient mortality in the hip fracture surgery cohort (OR 166.8, 95% CI 1.067-26064.7, p = 0.04) and a higher 30-day mortality in the CABG cohort (OR 4.55, 95% CI 1.01-20.49, p = 0.03).

CONCLUSIONS

Transfusing RBC units stored for greater than or equal to 28 days may be associated with a higher mortality for patients undergoing hip fracture or CABG.

Transfusion practices in traumatic brain injury

Purpose of review

The aim of this review is to summarize the recent studies looking at the effects of anemia and red blood cell transfusion in critically-ill patients with traumatic brain injury (TBI), describe the transfusion practice variations observed worldwide, and outline the ongoing trials evaluating restrictive versus liberal transfusion strategies for TBI.

Recent findings

Anemia is common among critically-ill patients with TBI, it is also thought to exacerbate secondary brain injury, and is associated with an increased risk of poor outcome. Conversely, allogenic red blood cell transfusion carries its own risks and complications, and has been associated with worse outcomes. Globally, there are large reported differences in the hemoglobin threshold used for transfusion after TBI. Observational studies have shown differential results for improvements in cerebral oxygenation and metabolism after red blood cell transfusion in TBI.

Summary

Currently, there is insufficient evidence to make strong recommendations regarding which hemoglobin threshold to use as a transfusion trigger in critically-ill patients with TBI. There is also uncertainty whether the restrictive transfusion strategy used in general critical care can be extrapolated to acutely brain injured patients. Ultimately, the consequences of anemia-induced cerebral injury need to be weighed up against the risks and complications associated with red blood cell transfusion.

Decreased Hemolysis and Improved Platelet Function in Blood Components Washed With Plasma-Lyte A Compared to 0.9% Sodium Chloride

OBJECTIVES

Washing cellular blood products is accepted to ameliorate repeated severe allergic reactions but is associated with RBC hemolysis and suboptimal platelet function. We compared in vitro hemolysis and platelet function in blood components after washing with Plasma-Lyte A (PL-A) vs normal saline (NS).

METHODS

RBC (n = 14) were washed/resuspended in NS or PL-A. Free hemoglobin and heme were determined at 0, 24, 48, and 72 hours. Platelet concentrates (PCs; n = 21) were washed with NS or PL-A and resuspended in same washing solution (n = 13) or ABO-identical plasma (n = 8). Platelet aggregation and spreading were evaluated.

RESULTS

The 24-hour free hemoglobin and heme levels were higher in NS (P < .05). Improved platelet function was observed in PL-A-washed PCs (P < .001).

DISCUSSION

PL-A showed less RBC hemolysis and better platelet function than NS. Whether such differences would occur in vivo is unknown.

The Age of BLood Evaluation (ABLE) randomised controlled trial: description of the UK-funded arm of the international trial, the UK cost-utility analysis and secondary analyses exploring factors associated with health-related quality of life and health-care costs during the 12-month follow-up

BACKGROUND

At present, red blood cells (RBCs) are stored for up to 42 days prior to transfusion. The relative effectiveness and safety of different RBC storage times prior to transfusion is uncertain.

OBJECTIVE

To assess the clinical effectiveness and cost-effectiveness of transfusing fresher RBCs (stored for ≤ 7 days) compared with current standard-aged RBCs in critically ill patients requiring blood transfusions.

DESIGN

The international Age of BLood Evaluation (ABLE) trial was a multicentre, randomised, blinded trial undertaken in Canada, the UK, the Netherlands and France. The UK trial was funded to contribute patients to the international trial and undertake a UK-specific health economic evaluation.

SETTING

Twenty intensive care units (ICUs) in the UK, as part of 64 international centres.

PARTICIPANTS

Critically ill patients aged ≥ 18 years (≥ 16 years in Scotland) expected to require mechanical ventilation for ≥ 48 hours and requiring a first RBC transfusion during the first 7 days in the ICU.

INTERVENTIONS

All decisions to transfuse RBCs were made by clinicians. One patient group received exclusively fresh RBCs stored for ≤ 7 days whenever transfusion was required from randomisation until hospital discharge. The other group received standard-issue RBCs throughout their hospital stay.

MAIN OUTCOME MEASURES

The primary outcome was 90-day mortality. Secondary outcomes included development of organ dysfunction, new thrombosis, infections and transfusion reactions. The primary economic evaluation was a cost-utility analysis.

RESULTS

The international trial took place between March 2009 and October 2014 (UK recruitment took place between January 2012 and October 2014). In total, 1211 patients were assigned to receive fresh blood and 1219 patients to receive standard-aged blood. RBCs were stored for a mean of 6.1 days [standard deviation (SD) ± 4.9 days] in the group allocated to receive fresh blood and 22.0 days (SD ± 8.4 days) in the group allocated to receive standard-aged blood. Patients received a mean of 4.3 RBC units (SD ± 5.2 RBC units) and 4.3 RBC units (SD ± 5.5 RBC units) in the groups receiving fresh blood and standard-aged blood, respectively. At 90 days, 37.0% of patients in the group allocated to receive fresh blood and 35.3% of patients in the group allocated to receive standard-aged blood had died {absolute risk difference 1.7% [95% confidence interval (CI) -2.1% to 5.5%]}. There were no between-group differences in any secondary outcomes. The UK cohort comprised 359 patients randomised and followed up for 12 months for the cost-utility analysis. UK patients had similar characteristics and outcomes to the international cohort. Mean total costs per patient were £32,346 (95% CI £29,306 to £35,385) in the group allocated to receive fresh blood and £33,353 (95% CI £29,729 to £36,978) in the group allocated to receive standard-aged blood. Approximately 85% of the total costs were incurred during the index hospital admission. There were no significant cost differences between the two groups [mean incremental costs for those receiving fresh vs. standard-aged blood: -£231 (95% CI -£4876 to £4415)], nor were there significant differences in outcomes (mean difference in quality-adjusted life-years -0.010, 95% CI -0.078 to 0.057).

LIMITATIONS

Adverse effects from the exclusive use of older RBCs compared with standard or fresh RBCs cannot be excluded.

CONCLUSIONS

The use of RBCs aged ≤ 7 days confers no clinical or economic benefit in critically ill patients compared with standard-aged RBCs.

FUTURE WORK

Future studies should address the safety of RBCs near the end of the current permitted storage age.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN44878718.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 62. See the NIHR Journals Library website for further project information. The international ABLE trial was also supported by peer-reviewed grants from the Canadian Institutes of Health Research (177453), Fonds de Recherche du Québec - Santé (24460), the French Ministry of Health Programme Hospitalier de Recherche Clinique (12.07, 2011) and by funding from Établissement Français du Sang and Sanquin Blood Supply.

Transfusion of packed red blood cells at the end of shelf life is associated with increased risk of mortality - a pooled patient data analysis of 16 observational trials

Observational studies address packed red blood cell effects at the end of shelf life and have larger sample sizes compared to randomized control trials. Meta-analyses combining data from observational studies have been complicated by differences in aggregate transfused packed red blood cell age and outcome reporting. This study abrogated these issues by taking a pooled patient data approach. Observational studies reporting packed red blood cell age and clinical outcomes were identified and patient-level data sets were sought from investigators. Odds ratios and 95% confidence intervals for binary outcomes were calculated for each study, with mean packed red blood cell age or maximum packed red blood cell age acting as independent variables. The relationship between mean packed red blood cell age and hospital length of stay for each paper was analyzed using zero-inflated Poisson regression. Random effects models combined paper-level effect estimates. Extremes analyses were completed by comparing patients transfused with mean packed red blood cell aged less than ten days to those transfused with mean packed red blood cell aged at least 30 days. sixteen datasets were available for pooled patient data analysis. Mean packed red blood cell age of at least 30 days was associated with an increased risk of in-hospital mortality compared to mean packed red blood cell of less than ten days (odds ratio: 3.25, 95% confidence interval: 1.27–8.29). Packed red blood cell age was not correlated to increased risks of nosocomial infection or prolonged length of hospital stay.

Age of transfused blood in critically ill adult trauma patients: a prespecified nested analysis of the Age of Blood Evaluation randomized trial

BACKGROUND

Blood transfusion is common in the resuscitation of patients with traumatic injury. However, the clinical impact of the length of storage of transfused blood is unclear in this population.

STUDY DESIGN AND METHODS

We undertook a prespecified nested analysis of 372 trauma victims of the 2510 critically ill patients from 64 centers treated as part of the Age of Blood Evaluation (ABLE) randomized controlled trial. Patients were randomized according to their trauma status to receive either a transfusion of fresh blood stored not more than 7 days or standard-issue blood. Our primary outcome was 90-day all-cause mortality.

RESULTS

Overall, 186 trauma patients received fresh blood and 186 received standard-issue blood. Adherence to transfusion protocol was 94% (915/971) for all fresh blood transfused and 100% (753/753) for all standard-issue blood transfused. Mean ± SD blood storage duration was 5.6 ± 3.8 days in the fresh group and 22.7 ± 8.4 days in the standard-issue group (p < 0.001). Ninety-day mortality in the fresh group was 21% (38/185), compared to 16% (29/184) in the standard-issue group, with an unadjusted absolute risk difference of 5% (95% confidence interval [CI], -3.1 to 12.6) and an adjusted absolute risk difference of 2% (95% CI, -3.5 to 6.8).

CONCLUSION

In critically ill trauma patients, transfusion of fresh blood did not decrease 90-day mortality or secondary outcomes, a finding similar to the overall population of the ABLE trial.

Study of the pharmacokinetics of polymerized porcine hemoglobin (pPolyHb)

Polymerized porcine hemoglobin (pPolyHb), a kind of glutaraldehyde-polymerized haemoglobin-based oxygen carrier, was developed as a potential red blood substitute for clinical applications. Assessment of its absorption, distribution, and metabolism is a major determinant of its safety and efficacy. In this study, a series of pharmacokinetic parameters of pPolyHb were measured and calculated in different animal models, such as the top-load model, the 50% exchange transfusion model and the haemorrhagic shock model. The results showed that the kinetic process of pPolyHb in rats conforms to the laws of linear pharmacokinetics in vivo. The half-life of pPolyHb was superior and more stable under non-pathological conditions, but in clinical situations such as trauma and anaemia, the half-life of pPolyHb may decline. The study of clearance (CL) and the apparent volume of distribution (Vd) of pPolyHb in these three different animal models demonstrated longer residence and a predominant, targeted role of pPolyHb with little accumulation in tissues. Through this study, the superior pharmacokinetic characteristics of pPolyHb have been proved and will aid in the determination of a reasonable dosing regimen and administration interval in clinical situations.

Packed Red Blood Cell Transfusion in Older Adults: A Systematic Review

Most packed red blood cell (PRBC) transfusion research focuses on younger patient populations (younger than 65) given the complexity of care and presence of comorbidities in older adults. The purpose of the current study was to critically examine the current evidence related to PRBC transfusion among older adults (age ≥65). PubMed, CINAHL, and Embase were searched for randomized controlled trials that evaluated blood transfusion in any manner (e.g., prevention, associated outcomes). Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, the search resulted in 10 studies focused on cardiac, orthopedic, and gastrointestinal surgery patients. SQUIRE (Standards for QUality Improvement Reporting Excellence) guidelines were used to evaluate studies for bias; the average bias score was 13.0 (SD = 3.4), indicating a low level of bias. Greatest sources of bias were methods to assess completeness/accuracy of data, details about missing data, and costs associated with the study. Interventions to prevent PRBC transfusion in older adults vary widely, and outcomes associated with PRBC transfusion in older adults require further evaluation. [Journal of Gerontological Nursing, 44(3), 39-46.].

Hemodynamic Functionality of Transfused Red Blood Cells in the Microcirculation of Blood Recipients

The primary goal of red blood cell (RBC) transfusion is to supply oxygen to tissues and organs. However, due to a growing number of studies that have reported negative transfusion outcomes, including reduced blood perfusion, there is rising concern about the risks in blood transfusion. RBC are characterized by unique flow-affecting properties, specifically adherence to blood vessel wall endothelium, cell deformability, and self-aggregability, which define their hemodynamic functionality (HF), namely their potential to affect blood circulation. The role of the HF of RBC in blood circulation, particularly the microcirculation, has been documented in numerous studies with animal models. These studies indicate that the HF of transfused RBC (TRBC) plays an important role in the transfusion outcome. However, studies with animal models must be interpreted with reservations, as animal physiology may not reflect human physiology. To test this concept in humans, we have directly examined the effect of the HF of TRBC, as expressed by their deformability and adherence to vascular endothelium, on the transfusion-induced effect on the skin blood flow and hemoglobin increment in β-thalassemia major patients. The results demonstrated, for the first time in humans, that the TRBC HF is a potent effector of the transfusion outcome, expressed by the transfusion-induced increase in the recipients' hemoglobin level, and the change in the skin blood flow, indicating a link between the microcirculation and the survival of TRBC in the recipients' vascular system. The implication of these findings for blood transfusion practice and to vascular function in blood recipients is discussed.

Consequences of Transfusing Blood Components in Patients With Trauma: A Conceptual Model

Transfusion of blood components is often required in resuscitation of patients with major trauma. Packed red blood cells and platelets break down and undergo chemical changes during storage (known as the storage lesion) that lead to an inflammatory response once the blood components are transfused to patients. Although some evidence supports a detrimental association between transfusion and a patient's outcome, the mechanisms connecting transfusion of stored components to outcomes remain unclear. The purpose of this review is to provide critical care nurses with a conceptual model to facilitate understanding of the relationship between the storage lesion and patients' outcomes after trauma; outcomes related to trauma, hemorrhage, and blood component transfusion are grouped according to those occurring in the short-term (≤30 days) and the long-term (>30 days). Complete understanding of these clinical implications is critical for practitioners in evaluating and treating patients given transfusions after traumatic injury.

Fresh versus old red cell transfusions: what have the recent clinical trials found?

PURPOSE OF REVIEW

Red blood cell transfusion is a common treatment for anaemia worldwide, but concerns continue to be raised about adverse effects of cellular blood components, which are biological products. One hypothesis for the adverse effects associated with blood transfusion is the harmful effects of storage on red cells that have been demonstrated in laboratory and animal studies. Over the past few years, a number of more significant randomized controlled trials comparing 'fresh' versus 'older' blood have been published in an attempt to address the clinical consequences of storage age, with two further large trials ongoing.

RECENT FINDINGS

These recent trials enrolled approximately 4000 participants across a variety of populations - cardiac surgical, critically ill, paediatric and acute hospitalized in-patients. All trials achieved statistically significant separation of red cell storage duration between both groups. The results of all these trials have found no clinical benefit to using fresher red cells when compared with older or standard-issue red cells. However, certain subgroups of patients either receiving red cells stored at more extreme ages of storage or those with additional risks for impaired microcirculations (critically ill elderly, severe sepsis and major haemorrhage) were either underrepresented or not included in these trials.

SUMMARY

At present, on the basis of recent trials, there is no indication for blood transfusion services to implement preferential utilization of fresher red cell units.

The Effects of Red Blood Cell Transfusion on Functional Outcome after Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

The optimal red blood cell transfusion (RBCT) trigger for patients with aneurysmal subarachnoid hemorrhage (SAH) is unknown. In patients with cerebral vasospasm, anemia may increase susceptibility to ischemic injury; conversely, RBCT may worsen outcome given known deleterious effects.

OBJECTIVE

To examine the association between RBCT, delayed cerebral ischemia (DCI), vasospasm, and outcome after SAH.

METHODS

A total of 421 consecutive patients with SAH, admitted to a neurocritical care unit at a university-affiliated hospital and who underwent surgical occlusion of their ruptured aneurysm were retrospectively identified from a prospective observational database. Propensity score methods were used to reduce the bias associated with treatment selection.

RESULTS

Two hundred and sixty-one patients (62.0%) received an RBCT. Angiographic vasospasm (odds ratio [OR] 1.6; 95% confidence interval [CI], 1.1-2.3; P = 0.025) but not severe angiographic spasm, DCI, or delayed infarction was associated with RBCT. A total of 283 patients (67.2%) experienced a favorable outcome, defined as good or moderately disabled on the Glasgow Outcome Scale; 47 (11.2%) were severely disabled or vegetative and 91 patients (21.6%) were dead at 6-month follow-up. Among patients who survived ≥2 days, RBCT was associated with unfavorable outcome (OR, 2.6; 95% CI, 1.6-4.1). Transfusion of ≥3 units of blood was associated with an increased incidence of unfavorable outcome. Propensity analysis to control for the probability of exposure to RBCT conditional on observed covariates measured before RBCT indicates that RBCT is associated with unfavorable outcome in the absence of DCI (OR, 2.17; 95% CI, 1.56-3.01; P < 0.0001) but not when DCI is present (OR, 0.82; 95% CI, 0.35-1.92; P = 0.65).

CONCLUSIONS

Blood transfusions are associated with unfavorable outcome after SAH particularly when DCI is absent. Propensity analysis suggests that RBCT may be associated with poor outcome rather than being a marker of disease severity. However, when DCI is present, RBCT may help improve outcome.

From Donor to Recipient: Considerations for Blood Transfusion Outcomes Research

Donated blood can be broken down into blood components for use in patient care. This article focuses primarily on packed red blood cells (PRBCs), as they experience breakdown during storage that may adversely impact patient outcomes. Patients require PRBC transfusions for a number of clinical reasons. Although transfusions of PRBCs provide some clinical benefit, they are also associated with increased morbidity and mortality across multiple patient populations, albeit the mechanisms underlying this relationship remain unclear. With an aging, more acutely ill population requiring aggressive treatment and a lack of transfusion alternatives, research focused on PRBCs has gained momentum. Proper interpretation of research findings on the part of clinicians depends on accurate data collection that includes aspects of both the transfused blood components and the recipients. The purpose of this article is to examine stored PRBC factors, blood-donor characteristics, transfusion-specific factors, and patient-specific characteristics as they relate to patient outcomes research. Challenges associated with performing and interpreting outcomes of transfusion-related research are presented. Implications of current evidence for patient care, such as awareness of benefits as well as risks associated with blood component transfusion, are also provided.

Red blood cell storage time and transfusion: current practice, concerns and future perspectives

Red blood cells (RBCs) units are the most requested transfusion product worldwide. Indications for transfusion include symptomatic anaemia, acute sickle cell crisis, and acute blood loss of more than 30% of the blood volume, with the aim of restoring tissue oxygen delivery. However, stored RBCs from donors are not a qualitative equal product, and, in many ways, this is a matter of concern in the transfusion practice. Besides donor-to-donor variation, the storage time influences the RBC unit at the qualitative level, as RBCs age in the storage bag and are exposed to the so-called storage lesion. Several studies have shown that the storage lesion leads to post-transfusion enhanced clearance, plasma transferrin saturation, nitric oxide scavenging and/or immunomodulation with potential unwanted transfusion-related clinical outcomes, such as acute lung injury or higher mortality rate. While, to date, several studies have claimed the risk or deleterious effects of "old" vs "young" RBC transfusion regimes, it is still a matter of debate, and consideration should be taken of the clinical context. Transfusion-dependent patients may benefit from transfusion with "young" RBC units, as it assures longer inter-transfusion periods, while transfusion with "old" RBC units is not itself harmful. Unbiased Omics approaches are being applied to the characterisation of RBC through storage, to better understand the (patho)physiological role of microparticles (MPs) that are found naturally, and also on stored RBC units. Perhaps RBC storage time is not an accurate surrogate for RBC quality and there is a need to establish which parameters do indeed reflect optimal efficacy and safety. A better Omics characterisation of components of "young" and "old" RBC units, including MPs, donor and recipient, might lead to the development of new therapies, including the use of engineered RBCs or MPs as cell-based drug delivering tools, or cost-effective personalised transfusion strategies.

Transfusion of 35-day-stored red blood cells does not alter lipopolysaccharide tolerance during human endotoxemia

BACKGROUND

Transfusion-related immunomodulation (TRIM) encompasses immunosuppressive and proinflammatory effects induced by red blood cell (RBC) transfusion. Changes that occur during storage in the RBC product have been hypothesized to underlie TRIM, mediated by tolerance of toll-like receptors (TLR). We investigated whether transfusion of 35-day-stored autologous RBCs alters cytokine production in response to stimulation with lipopolysaccharide (LPS) or lipotheic acid (LTA), in a clinically relevant model of endotoxemia.

STUDY DESIGN AND METHODS

Eighteen volunteers received 2 ng/kg LPS intravenously, followed by normal saline or 2- or 35-day-stored autologous RBC transfusion. Before LPS, before transfusion, and 6 hours after transfusion blood was collected to measure cytokine gene expression. Whole blood was used for ex vivo stimulation with LPS and LTA, after which cytokine levels were measured with enzyme-linked immunosorbent assay.

RESULTS

In vivo LPS induced a biphasic response in cytokine mRNA with peak values 2 hours after LPS infusion. Storage time of RBC transfusion did not influence cytokine mRNA levels. In vivo infusion of LPS resulted in tolerance for ex vivo stimulation with LPS and LTA. However, transfusion of either fresh or stored RBCs did not further affect the capacity to produce cytokines after ex vivo stimulation.

CONCLUSION

In a clinically relevant model of human endotoxemia, autologous transfusion of 35-day-stored RBCs does not influence cytokine mRNA levels nor does it change the capacity of white blood cells in whole blood to produce cytokines after ex vivo stimulation with LPS or LTA.

Modeling the potential impact on the US blood supply of transfusing critically ill patients with fresher stored red blood cells

Background

Although some studies have suggested that transfusion recipients may have better medical outcomes if transfused with red blood cell units stored for a short time, the overall body of evidence shows mixed results. It is important to understand how using fresher stored red blood cell units for certain patient groups may affect blood availability.

Methods

Based on the Stock-and-Flow simulation model of the US blood supply developed by Simonetti et al. 2014, we evaluated a newly implemented allocation method of preferentially transfusing fresher stored red blood cell units to a subset of high-risk group of critically ill patients and its potential impact on supply.

Results

Simulation results showed that, depending on the scenario, the US blood total supply might be reduced between 2-42%, when compared to the standard of care in transfusion medicine practice. Among our simulated scenarios, we observed that the number of expired red blood cell units modulated the supply levels. The age threshold of the required red blood cell units was inversely correlated with both the supply levels and the number of transfused units that failed to meet that age threshold.

Conclusion

To our knowledge, this study represents the first attempt to develop a comprehensive framework to evaluate the impact of preferentially transfusing fresher stored red blood cells to the higher-risk critically ill patients on supply. Model results show the difficulties to identify an optimal scenario.

Hitchhiker's guide to the red cell storage galaxy: Omics technologies and the quality issue

Red blood cell storage in the blood bank makes millions of units of available for transfusion to civilian and military recipients every year. From glass bottles to plastic bags, from anticoagulants to complex additives, from whole blood to leukocyte filtered packed red blood cells: huge strides have been made in the field of blood component processing and storage in the blood bank during the last century. Still, refrigerated preservation of packed red blood cells under blood bank conditions results in the progressive accumulation of a wide series of biochemical and morphological changes to the stored erythrocytes, collectively referred to as the storage lesion(s). Approximately ten years ago, retrospective clinical evidence had suggested that such lesion(s) may be clinically relevant and mediate some of the untoward transfusion-related effects observed especially in some categories of recipients at risk (e.g. massively or chronically transfused recipients). Since then, randomized clinical trials have failed to prospectively detect any signal related to red cell storage duration and increased morbidity and mortality in several categories of recipients, at the limits of the statistical power of these studies. While a good part of the transfusion community has immediately adopted the take-home message "if it isn't broken, don't fix it" (i.e. no change to the standard of practice should be pursued), decision makers have been further questioning whether there may be room for further improvements in this field. Provocatively, we argue that consensus has yet to be unanimously reached on what makes a good quality marker of the red cell storage lesion and transfusion safety/efficacy. In other words, if it is true that "you can't manage what you can't measure", then future advancements in the field of transfusion medicine will necessarily rely on state of the art analytical omics technologies of well-defined quality parameters. Heavily borrowing from Douglas Adam's imaginary repertoire from the world famous "Hitchhiker's guide to the galaxy", we briefly summarize how some of the principles for intergalactic hitchhikers may indeed apply to inform navigation through the complex universe of red cell storage quality, safety and efficacy.

Storage time of intraoperative transfused allogeneic red blood cells is not associated with new-onset postoperative atrial fibrillation in cardiac surgery

BACKGROUND

Allogeneic red blood cell (RBC) transfusion has been associated with new-onset postoperative atrial fibrillation (POAF) following cardiac surgery. Prolonged storage time of RBC may increase the risk. The primary aim of the study was to evaluate whether the storage time of RBC is associated with development of POAF.

MATERIALS AND METHODS

Pre-, per- and postoperative data were retrieved from the Western Denmark Heart Registry and local blood banks regarding patients who underwent coronary artery bypass surgery, valve surgery or combined procedures in Aalborg or Aarhus University Hospital during 2010-2014. Multiple logistic regression was used to determine the risk of POAF according to transfusion of RBC on the day of surgery. Furthermore, we determined trend in storage time of RBC according to risk of POAF using restricted cubic splines. Patients with a history of preoperative atrial fibrillation, patients who received transfusions preoperative and patients who died at the day of surgery were among excluded patients.

RESULTS

A total of 2,978 patients with a mean age of 66.4 years were included and 609 patients (21%) received RBC transfusion on the day of surgery. POAF developed in 752 patients (25%) and transfused patients were at an increased risk compared with non-transfused patients (adjusted Odds Ratios for patients receiving RBC: 1.37; 95% CI: 1.11-1.69, P-value = 0.004). However, RBC transfusion was not necessarily the cause of POAF and may only be a marker for development of POAF. There was no significant association between storage time of RBC and POAF.

CONCLUSIONS

In contrast to intraoperative allogeneic RBC transfusion in general, increased storage time of RBC is not associated with development of POAF in cardiac surgery.

Association of Blood Component Ratio With Clinical Outcomes in Patients After Trauma and Massive Transfusion: A Systematic Review

Component ratios that mimic whole blood may produce survival benefit in patients massively transfused after trauma; other outcomes have not been reviewed. The purpose of this review was to systematically analyze studies where clinical outcomes were compared on the basis of the component ratios administered during massive transfusion in adult patients after trauma. PubMed, CINAHL, and MEDLINE (Ovid) were searched for studies published in English between 2007 and 2015, performed at Level I or major trauma centers. Twenty-one studies were included in the analysis. We used an adapted 9-item instrument to assess bias risk. The average bias score for the studies was 2.86 ± 1.39 out of 16, indicating a low bias risk. The most common bias sources were lack of data about primary outcomes and adverse events. Those who received high ratios experienced not only greater survival benefit but also higher rates of multiple-organ failure; all other clinical outcomes findings were equivocal.

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.

Past, present and forecast of transfusion medicine: What has changed and what is expected to change?

Blood transfusion is the second most used medical procedures in health care systems worldwide. Over the last few decades, significant changes have been evolved in transfusion medicine practices. These changes were mainly needed to increase safety, efficacy, and availability of blood products as well as reduce recipients' unnecessary exposure to allogeneic blood. Blood products collection, processing, and storage as well as transfusion practices throughout all patient populations were the main stream of these changes. Health care systems across the world have adopted some or most of these changes to reduce transfusion risks, to improve overall patients' outcome, and to reduce health care costs. In this article, we are going to present and discuss some of these recent modifications and their impact on patients' safety.

Transfusion of platelets, but not of red blood cells, is independently associated with nosocomial infections in the critically ill

BACKGROUND

Red blood cell (RBC) transfusion has been associated with nosocomial infection in the critically ill patients. However, this association may be confounded by length of stay, as prolonged intensive care unit (ICU stay) increases both risk of infection and risk of transfusion. Also, it is not known whether specific blood products have differential risks.

METHODS

In this prospective multicentre cohort study, the risk of bacterial infections associated with transfusion products in critically ill (ICU) patients was determined in an integrated statistical model, using Cox proportional hazard analysis to account for attrition bias. In all acutely admitted patients with a length of stay of >48 h between 1 January 2011 and 31 December 2012, the occurrence of nosocomial infections in the ICU was prospectively monitored using CDC criteria.

RESULTS

Of 3502 screened patients, 476 (13.6 %) developed a nosocomial infection. These patients had higher APACHE IV scores, had longer ICU length of stay and were more frequently transfused compared to patients without an infection. Logistic regression showed that RBC transfusion was a risk factor for infection [odds ratio (OR) 1.98, 95 % confidence interval (CI) 1.54-2.55, p < 0.001], as well the number of RBC units transfused (OR 1.04, 95 % CI 1.03-1.06, p < 0.001). However, these associations disappeared in the Cox proportional hazard analysis. In contrast, we found an association between plasma transfusion and infection [hazard ratio (HR) 1.36, 95 % CI 1.10-1.69, p = 0.004] and between platelet transfusion and infection (HR 1.46, 95 % CI 1.18-1.81, p < 0.001). However, only platelet transfusion was associated with infection independently from other transfusion products (HR 1.40, 95 % CI 1.03-1.90, p = 0.03).

CONCLUSIONS

In critically ill patients, transfusion of platelets, but not of RBCs and plasma, is an independent risk factor for acquiring a nosocomial infection.

Anemia management after acute brain injury

Anemia is frequent among brain-injured patients, where it has been associated with an increased risk of poor outcome. The pathophysiology of anemia in this patient population remains multifactorial; moreover, whether anemia merely reflects a higher severity of the underlying disease or is a significant determinant of the neurological recovery of such patients remains unclear. Interestingly, the effects of red blood cell transfusions (RBCT) in moderately anemic patients remain controversial; although hemoglobin levels are increased, different studies observed only a modest and inconsistent improvement in cerebral oxygenation after RBCT and raised serious concerns about the risk of increased complications. Thus, considering this "blood transfusion anemia paradox", the optimal hemoglobin level to trigger RBCT in brain-injured patients has not been defined yet; also, there is insufficient evidence to provide strong recommendations regarding which hemoglobin level to target and which associated transfusion strategy (restrictive versus liberal) to select in this patient population. We summarize in this review article the more relevant studies evaluating the effects of anemia and RBCT in patients with an acute neurological condition; also, we propose some potential strategies to optimize transfusion management in such patients.