Blood still kills: six strategies to further reduce allogeneic blood transfusion-related mortality

Risk factors for blood transfusion in patients undergoing hysterectomy for stage I endometrial cancer

PURPOSE

To highlight the risk factors contributing to blood transfusion among patients undergoing surgical intervention for Stage I Endometrial Cancer (EC).

METHOD

Using the American College of Surgeons National Surgical Quality Improvement Program database, a nationally validated database dedicated to improving surgical care, females over the age of 18 who underwent surgery for EC stage I between the years 2016-2022 were queried. The cohort was then characterized based on those who received blood transfusion 72 h postoperatively.

RESULTS

27,183 patients with endometrial cancer who received surgical management were identified. 668 (2.5%) of those patients received blood transfusions. A multivariate logistic model found that a medical factor low preoperative Hct % (aOR 22.4, 95% CI[17.7, 28.3]; p < 0.001) and surgical factors such as 180 min or more of operative time (aOR 3.38, 95% CI[2.77, 4.14]; p < 0.001), larger uteri of 250-500 g (aOR 1.93, 95% CI[1.48, 2.49]; p < 0.001) and ≥ 500 g (aOR 2.35, 95% CI[1.77, 3.12]; p < 0.001), and abdominal approach compared to laparoscopic (aOR 6.36,95% CI[4.95, 8.18]; p < 0.001) were significantly associated with receiving blood transfusion.

CONCLUSION

Many significant risk factors were found to be associated with blood transfusions in patients with Stage I endometrial cancer. These findings allow surgeons to proactively prepare adequate measures for patients who may require blood transfusions when they undergo surgery for endometrial cancer.

An Analysis of the Association of Whole Blood Transfusion With the Development of Acute Respiratory Distress Syndrome

OBJECTIVES

To determine the association of whole blood and other blood products (components, prothrombin complex concentrate, and fibrinogen concentrate) with the development of acute respiratory distress syndrome (ARDS) among blood recipients.

DESIGN

Retrospective cohort study.

SETTING

American College of Surgeons Trauma Quality Improvement Program (TQIP) database between 2020 and 2021.

PATIENTS

Patients 15 years old or older in the TQIP database between 2020 and 2022 who received at least one blood product.

INTERVENTIONS

We compared characteristics and blood product administration between patients who developed ARDS versus those who did not.

MEASUREMENTS AND MAIN RESULTS

There were 134,863 that met inclusion for this analysis. Within the included population, 1% (1927) was diagnosed with ARDS. The no ARDS group had a lower portion of serious injuries to the head/neck (31% vs. 46%), thorax (51% vs. 78%), abdomen (34% vs. 48%), and extremities (37% vs. 47%). The median composite Injury Severity Score was 21 (11-30) in the no ARDS group vs. 30 (22-41) in the ARDS group. Unadjusted survival of discharge was 74% in the no ARDS group vs. 61% in the ARDS group. In our multivariable model, we found that whole blood (unit odds ratio [uOR], 1.05; 95% CI, 1.02-1.07), male sex (odds ratio, 1.44; 95% CI, 1.28-1.63), arrival shock index (uOR, 1.03; 95% CI, 1.01-1.06), and composite Injury Severity Score (uOR, 1.03; 95% CI, 1.03-1.04) were associated with the development of ARDS. These persisted on sensitivity testing.

CONCLUSIONS

We found an association between whole blood and the development of ARDS among trauma patients who received blood transfusions. Contrary to previous studies, we found no association between ARDS and fresh frozen plasma administration. The literature would benefit from further investigation via prospective study designs.

Pediatric WNT medulloblastoma predisposition in intraoperative blood loss: a retrospective observational cohort study

Introduction

Molecular subgroups influence the vascular architecture within medulloblastomas, particularly the wingless (WNT) subgroup, which contributes to its propensity for primary tumor hemorrhage. Whether this mechanism affects intraoperative blood loss remains unknown. This study aimed to assess the association between WNT medulloblastoma and the predisposition for blood loss.

Methods

This was a retrospective observational study using data from a neuro-oncology center comprising molecular data on patients treated between December 31, 2014, and April 30, 2023. Differences between WNT and other subgroups in the risk of primary outcome-intraoperative blood loss were assessed using multivariable-adjusted linear regression.

Results

Of the 148 patients included in the analysis, 18 patients (12.2%) had WNT, 42 (28.4%) had sonic hedgehog (SHH) TP53-wildtype, 7 (4.7%) had SHH TP53-mutant, and 81 (54.7%) were non-WNT/ non-SHH. The WNT subgroup more frequently underwent primary intratumoral hemorrhage (22% vs. 3.8%; p = 0.011). The median intraoperative blood loss was 400.00 (interquartile range [IQR] 250, 500) mL for WNT and 300.00 [200, 400] mL for the other subgroups (p = 0.136), with an adjusted β of 135.264 (95% confidence intervals [CI], 11.701-258.827; p = 0.032). Similar results were observed in both midline and noninfiltrative margin medulloblastoma.

Discussion

WNT medulloblastoma is typically associated with primary intratumoral hemorrhage and intraoperative blood loss. The validity of determining the surgical approach based on predicted molecular subtypes from imaging data is questionable. However, attempting to engage in risk communication with patients in a molecular-specific way is worthwhile to validate.

A Transfusion Regimen With Same-donor Packed Red Blood Cells Reduces Exposure to Multiple Blood Donors in Craniosynostosis Surgery

In major craniosynostosis surgery with moderate to severe blood loss, patients may be exposed to multiple donors. We have previously reported a method for reducing donor exposure using mixed pediatric units including plasma. To further reduce donor exposure, we used plasma-free divided pediatric units. The study aimed to investigate the feasibility of the new strategy for reducing donor exposure. This prospective observational study recruited children younger than 1 year who were scheduled for nonsyndromic craniosynostosis surgery. One adult red blood cell unit was divided into 4 equal units on the day before the operation for use intra- or postoperatively. Number of donor exposures, estimated blood loss, crystalloid, colloid, and blood product volumes, and coagulation parameters were evaluated. Nineteen infants were included. The mean estimated blood loss was 19 (3) mL/kg and the transfusion volume was 17 (7) mL/kg. The median donor exposure per patient was 1 (range, 1-3). During surgery, all infants received at least one DPU. Two infants received transfusions from more than one donor during the intraoperative period. In the first 24 hours postoperatively, 14 infants received transfusion; 10 received only DPUs, whereas 4 received from multiple donors. In all, multiple donor exposure was prevented in 14 of 19 infants. Postoperative Pk-INR was 1.33 (0.16); no plasma or platelets were transfused. The plasma-free DPU transfusion protocol may be useful to reduce donor exposure in open craniosynostosis surgery in infants.

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.

Transfusion-Transmitted Disorders 2023 with Special Attention to Bone Marrow Transplant Patients

Transfusion medicine is traditionally a strong/fundamental part of clinical practice, saving hundreds of millions of lives. However, blood-borne or transmitted infections are a well-known and feared possibility, a risk we relentlessly mitigate. Pathogens are continuously and rather quickly changing, so during the last decade, many, sometimes exotic, new pathogens and diseases were recorded and analyzed, and some of them were proved to be transmitted with transfusions. Blood or blood component transfusions are carried out after cautious preparative screening and inactivation maneuvers, but in some instances, newly recognized agents might escape from standard screening and inactivation procedures. Here, we try to focus on some of these proven or potentially pathogenic transfusion-transmitted agents, especially in immunocompromised patients or bone marrow transplantation settings. These pathogens are sometimes new challenges for preparative procedures, and there is a need for more recent, occasionally advanced, screening and inactivation methods to recognize and eliminate the threat a new or well-known pathogen can pose. Pathogen transmission is probably even more critical in hemophiliacs or bone marrow transplant recipients, who receive plasma-derived factor preparations or blood component transfusions regularly and in large quantities, sometimes in severely immunosuppressed conditions. Moreover, it may not be emphasized enough that transfusions and plasma-derived product administrations are essential to medical care. Therefore, blood-borne transmission needs continued alertness and efforts to attain optimal benefits with minimized hazards.

Supportive Care for Patients With Myelodysplastic Syndromes

ABSTRACT

Myelodysplastic syndromes are a heterogeneous group of bone marrow disorders characterized by ineffective hematopoiesis, progressive cytopenias, and an innate capability of progressing to acute myeloid leukemia. The most common causes of morbidity and mortality are complications related to myelodysplastic syndromes rather than progression to acute myeloid leukemia. Although supportive care measures are applicable to all patients with myelodysplastic syndromes, they are especially essential in patients with lower-risk disease who have a better prognosis compared with their higher-risk counterparts and require longer-term monitoring of disease and treatment-related complications. In this review, we will address the most frequent complications and supportive care interventions used in patients with myelodysplastic syndromes, including transfusion support, management of iron overload, antimicrobial prophylaxis, important considerations in the era of COVID-19 (coronavirus infectious disease 2019), role of routine immunizations, and palliative care in the myelodysplastic syndrome population.

Preoperative risk factors predict perioperative allogenic blood transfusion in patients undergoing primary lung cancer resections: a retrospective cohort study from a high-volume thoracic surgery center

BACKGROUND

Our study aimed to identify preoperative predictors for perioperative allogenic blood transfusion (ABT) in patients undergoing major lung cancer resections in order to improve the perioperative management of patients at risk for ABT.

METHODS

Patients admitted between 2014 and 2016 in a high-volume thoracic surgery clinic were retrospectively evaluated in a cohort study based on a control group without ABT and the ABT group requiring packed red blood cell units within 15 days postoperatively until discharge. The association of ABT with clinically established parameters (sex, preoperative anemia, liver and coagulation function, blood groups, multilobar resections) was analyzed by contingency tables, receiver operating characteristics (ROC) and logistic regression analysis, taking into account potential covariates.

RESULTS

60 out of 529 patients (11.3%) required ABT. N1 and non-T1 tumors, thoracotomy approach, multilobar resections, thoracic wall resections and Rhesus negativity were more frequent in the ABT group. In multivariable analyses, female sex, preoperative anemia, multilobar resections, as well as serum alanine-aminotransferase levels, thrombocyte counts and Rhesus negativity were identified as independent predictors of ABT, being associated with OR (95% Confidence interval, p-value) of 2.44 (1.23-4.88, p = 0.0112), 18.16 (8.73-37.78, p < 0.0001), 5.79 (2.50-13.38, p < 0.0001), 3.98 (1.73-9.16, p = 0.0012), 2.04 (1.04-4.02, p = 0.0390) and 2.84 (1.23-6.59, p = 0.0150), respectively.

CONCLUSIONS

In patients undergoing major lung cancer resections, multiple independent risk factors for perioperative ABT apart from preoperative anemia and multilobar resections were identified. Assessment of these predictors might help to identify high risk patients preoperatively and to improve the strategies that reduce perioperative ABT.

Storage of packed red blood cells impairs an inherent coagulation property of erythrocytes

Storage of packed red blood cells is associated with changes in erythrocytes that over time increasingly impair cellular function and potentially contribute to adverse effects associated with blood transfusion. Exposure of phosphatidylserine at the outer membrane leaflet of erythrocytes and shedding of microvesicles (MVs) during packed red blood cell storage are alterations assumed to increase the risk of prothrombotic events in recipients. Here, we used rotational thromboelastometry to study the coagulation process in blood samples with erythrocytes from stored PRBCs reconstituted with freshly prepared platelet-rich plasma. We explored the influence of following effects on the coagulation process: 1) PRBC storage duration, 2) differences between erythrocytes from stored PRBCs compared to freshly drawn erythrocytes, and 3) the contribution of added MVs. Interestingly, despite of a higher fraction of PS-positive cells, erythrocytes from PRBCs stored for 6 weeks revealed longer clotting times than samples with erythrocytes stored for 2 or 4 weeks. Further, clotting times and clot formation times were considerably increased in samples reconstituted with erythrocytes from stored PRBCs as compared to fresh erythrocytes. Moreover, MVs added to reconstituted samples elicited only comparably small and ambiguous effects on coagulation. Thus, this study provides no evidence for an amplified clotting process from prolonged storage of PRBCs but on the contrary implicates a loss of function, which may be of clinical significance in massive transfusion. Our observations add to the increasing body of evidence viewing erythrocytes as active players in the clotting process.

Six Sigma in blood transfusion services: A dream too big in a third world country?

BACKGROUND AND OBJECTIVES

Transfusion errors can occur anywhere from blood donation to final blood transfusion. They are a source of increased cost and patient mortality. Automated workflows can reduce transcription errors, but resource-poor centres still use semi-automated/manual method for testing including manual labelling of column agglutination cards/testing tubes. Missing out any details on these cards can lead to errors in reporting results, wastage and loss of resources and effort. The aim of this study was to implement Six Sigma DMAIC (Define, Measure, Analyse, Improve and Control) methodology to reduce transcription errors while labelling gel card in immunohaematology lab to zero defect.

MATERIALS AND METHODS

In this prospective study, transcription errors while manually performing 200 tests with 1400 opportunities were analysed. Baseline variables like number of errors, defects per million opportunities and sigma level in our current setup were measured. With the application of DMAIC methodology, root cause analysis for each error using Ishikawa diagram and structured Interviews were done to identify causes. A multipronged approach to deal with errors was done to improve critical areas using brainstorming sessions and developing training sheets for practice. After implementing the changes, baseline variables were reanalysed.

RESULTS

Application of DMAIC resulted in an overall reduction in defects from 34.86% to 0.56% with sigma level improvement from 1.89 to 4.08.

CONCLUSION

Six Sigma methodology can be used in a resource-poor setting even with lack of automation to ensure error-free process flow.

Guiding Principles for Surgical Pathways: A Tool for Improving Outcomes and Patient Safety

Surgical activity is an important aspect for the management of health and safety processes and from an organizational perspective is one of the most complex activities performed in hospitals. It is often a defining and high value feature for any healthcare facility while being one of the most high-risk procedures for patients with the highest number of avoidable adverse events. To ensure effective management of surgical pathways, they need to be considered from the perspective of clinical governance which takes a global approach to planning and management with the goal of improving safety and quality for patients. This paper contains the main features of this objective outlined within the document issued subsequent to the State-Regional Italian Government conference. This regulatory effort includes effective recommendations to make surgical pathways safer and more efficient with particular reference to lean management, patient blood management and patient safety.

A Concise Synopsis of Current Literature and Guidelines on the Practice of Plasma Transfusion

Evidence-based indications for plasma transfusion are limited, and much of the clinical practice relies on expert opinion. This article highlights key studies, meta-analyses, and guidelines for plasma transfusion in adults. The goal is to limit non-evidence-based plasma transfusion that is outside of clinical guideline, because as with all transfusions, the administration of plasma is not without risk. Any intended potential benefit must be appraised against the real risks associated with transfusion. Moving forward, the practice of plasma transfusion would benefit greatly from randomized controlled trials to update and expand the existing guidelines.

Genotyping versus phenotyping of non-ABO erythrocyte antigens in patients with the Mediterranean hemopathic syndromes: Effect of transfusion therapy

The Mediterranean hemopathic syndromes (MHS) are the most prevalent hemoglobinopathies in the Mediterranean basin. Transfusion therapy is the main therapy for these disorders, particularly for severe forms of the disease. Currently, pre-transfusion serological typing of erythrocyte antigens is the standard tool for reducing complications of transfusion in those patients. This study compared genotyping with phenotyping of non-ABO erythrocyte antigens in patients with MHS and assessed the effect of transfusion therapy on their results. One-hundred ninety-eight MHS patients were recruited, screened, and proven negative for allo-antibodies. They were grouped into two groups: (1) 20 newly diagnosed patients with no transfusion history and (2) 178 previously diagnosed patients undergoing transfusion therapy. Patients were interviewed and clinically examined. Full blood count (FBC) and high performance liquid chromatography (HPLC) were done for group 1 only. Genotyping and phenotyping of non-ABO erythrocyte antigens were performed for group 1, and 25 patients out of group 2 were propensity score-matched (PSM) with group 1. Both groups were gender and age matched; 55% and 74% of groups 1 and 2 had major disease, respectively. Insignificant differences were observed between genotyping and phenotyping of non-ABO erythrocyte antigens in group 1, while significant discrepancies and mixed field results were noted in group 2 patients. Discrepancies were obvious with JKa, JKb, and little c antigens. Conclusively, molecular typing is a powerful tool for pre-transfusion testing in chronically transfused MHS patients. This testing reduces incidence of transfusion reactions. JKa, JKb and little c antigens are the most clinically significant non-ABO erythrocyte antigens.

The Use of Recombinant Activated Factor VII in Patients with Glanzmann's Thrombasthenia

Platelet transfusion is the standard treatment to control or prevent bleeding in patients with Glanzmann's thrombasthenia (GT), but platelets are often unavailable. Recombinant activated factor VII (rFVIIa) is an effective alternative to platelets in patients with GT with past/present refractoriness to platelet transfusions and antibodies to platelets. However, there is an unmet need for an alternative to platelets in patients without antibodies. This report summarizes evidence of efficacy and safety of rFVIIa in patients with GT without refractoriness or antibodies to platelets from three different sources: the Glanzmann's Thrombasthenia Registry (GTR), published literature (January 01, 1999 to December 01, 2017), and the Novo Nordisk safety surveillance database. In the GTR, 133 patients received rFVIIa for the treatment of 333 bleeding episodes and prevention of bleeding in 157 surgical procedures. Overall efficacy rates were 79 and 88%, respectively, in patients treated for bleeding episodes or for the prevention of bleeding during surgery; effectiveness was generally similar across refractoriness/antibody status categories. Median dose per infusion of rFVIIa was close to that recommended for patients with GT (90 µg/kg). Data from 14 published case reports also demonstrated that rFVIIa is effective with an acceptable safety profile in patients with GT without antibodies to platelets. Analysis of adverse events reported in GTR and in Novo Nordisk safety surveillance database did not raise any new safety concerns. These data supported the label extension of rFVIIa to include cases where platelets are not readily available, which was approved by the European Medicines Agency in December 2018.

The routine use of platelet function tests in elective coronary artery bypass grafting: A prospective observational trial

BACKGROUND

Preoperative use of platelet function tests contributes to the decrease of re-intervention rate due to bleeding and the necessity of transfusion in coronary artery bypass grafting (CABG) patients. The aim was to investigate the predictive value and to justify routine preoperative use of multiple electrode aggregometry in these patients.

METHODS

A prospective observational trial which included 416 consecutive patients subjected to elective isolated CABG was conducted. The Multiplate® test was used to assess platelet function. Platelet function test results, postoperative blood loss, and transfusion requirements were compared between high and low bleeding risk patients. Receiver operating characteristic analysis was performed to assess the sensitivity and specificity of the arachidonic acid (ASPI) and adenosine di-phosphate high sensitive (ADPHS) tests.

RESULTS

ADPHS and ASPI test results significantly predicted total bleeding > 1000 ml (AUC, 0.685, p < .001; 0.695, p = .039). Sensitivity and specificity were 62.9% and 40.0%, for ADPHS ≤602, and 70.8% and 41.8%, for ASPI ≤ 453. The sensitivity and specificity of cut-off values recommended by the manufacturer were 84.2% and 40.0% for ADPHS ≤ 500, while for ASPI < 600 the values were 54.7% and 62.2%. More platelets and cryoprecipitate were transfused in patients with ADPHS ≤ 602.5 (p < .001; p = .035). Patients with ADPHS ≤ 500 had a higher rate of red blood count, platelet and cryoprecipitate transfusion (p<.001p<.001; p = .013). The manufacturer's ASPI test cut-off values showed no statistically significant prediction for a higher transfusion rate.

CONCLUSION

Preoperative platelet function tests should be conducted systematically for all elective CABG patients who were on dual antiplatelet therapy after adjusting test cut-off values for each population.

Implementation of Perioperative Point-of-Care Platelet Function Analyses Reduces Transfusion Requirements in Cardiac Surgery: A Retrospective Cohort Study

Background Platelet dysfunction is a common cause of bleeding, perioperative blood transfusion, and surgical re-exploration in cardiac surgical patients. We evaluated the effect of incorporating a platelet function analyzer utilizing impedance aggregometry (Multiplate, Roche, Munich, Germany) into our local transfusion algorithm on the rate of platelet transfusion and postoperative blood loss in patients undergoing coronary artery bypass grafting (CABG) surgery.

Methods Data were collected on patients undergoing CABG surgery from January 2015 to April 2017. Patients who underwent surgery before and after introduction of this algorithm were classified into prealgorithm and postalgorithm groups, respectively. The primary outcome was the rate of platelet transfusion before and after implementation of the Multiplate-based transfusion algorithm. Secondary outcomes included transfusion rate of packed red blood cells, postoperative blood loss at 12 and 24 hours, length of stay in the intensive care unit, and the hospital and mortality.

Results A total of 726 patients were included in this analysis with 360 and 366 patients in the pre- and postalgorithm groups, respectively. Transfusion rates of platelets (p = 0.01) and packed red blood cells (p = 0.0004) were significantly lower following introduction of the algorithm in patients (n = 257) who had insufficient time to withhold antiplatelet agents. Receiver operating characteristic curves defined optimal cutoff points of arachidonic acid and adenosine diphosphate assays on the Multiplate to predict future platelet transfusion were 23AU and 43AU, respectively.

Conclusions The introduction of a Multiplate-based platelet transfusion algorithm showed a statistically significant reduction in the administration of platelets to patients undergoing urgent CABG surgery.

Towards the understanding of the UV light, riboflavin and additive solution contributions to the in vitro lesions observed in Mirasol®-treated platelets

OBJECTIVES

Pathogen reduction technologies are implemented to increase the safety of blood products. We previously showed that the UVB alone significantly contributes to the storage lesions observed in platelets treated with riboflavin/UVB using a home-made illuminator. The present study aims at confirming these observations using the commercial Mirasol® technology.

METHODS

A three-arm study (untreated, UV-, Mirasol®-treated platelets) was conducted to investigate the platelet storage lesions throughout storage (n=4). A two-arm study was then designed to compare Intersol and T-PAS+ additive solutions (n=3). Phenotype and functional platelet characteristics were assessed using flow cytometry, aggregometry, antioxidant assays and metabolic parameters.

RESULTS

Mirasol®-treated platelets exhibit enhanced storage lesions compared to controls (increase of activation markers and glycolysis rate, lower hypotonic shock and double-agonist activation responses, and decrease of total antioxidant capacity). Here, we also confirmed that the UV radiation alone is causing platelet lesions. Riboflavin tends to have an intracellular protective role while it decreases the extracellular antioxidant defenses. Furthermore, benefits of platelet additive solutions containing potassium and magnesium were confirmed as it reduces the extent of storage lesions.

CONCLUSIONS

The photosensitizer, UV illumination and composition of the platelet additive solutions are key parameters influencing the platelet storage lesion. The clinical relevance of these findings is not fully understood and recent published clinical studies could not show increase in bleeding in patients receiving Mirasol-treated platelets. New developments in storage solutions might help to improve storage conditions of PRT-treated platelets and should be prioritised as research subject in the future.

Utilisation of emergency blood in a cohort of South African emergency centres with no direct access to a blood bank

Introduction

The transfusion of emergency blood is an essential part of haemostatic resuscitation. Locally, where direct access to a blood bank is limited, emergency blood is stored within emergency centres. It was previously suggested that stored blood provides inadequate volumes compared to what is needed. Minimal data are available regarding indications for emergency blood usage. We aimed to describe the utilisation of emergency blood in selected Cape Town emergency centres.

Materials and methods

A cross-sectional study was carried out at three secondary level emergency centres (no blood bank), and one tertiary centre (with a blood bank). Data from emergency blood recipients were recorded over a three-month study period. Indications for transfusion, number of units and location of transfusion were recorded. Indications and usage location were described in numbers and proportions.

Results

A total of 329 emergency blood units were transfused to 210 patients. Trauma accounted for 39% (n = 81) of cases and other surgical conditions for 22% (n = 47), particularly upper gastrointestinal 11% (n = 24) and perioperative bleeding 8% (n = 16). Medical conditions accounted for 15% (n = 31), with anaemia 13% (n = 27), the most prevalent indication. Gynaecological conditions accounted for 15% (n = 32), mostly ectopic pregnancy 8% (n = 17). The majority of emergency blood, 77% (n = 253) were used in the emergency centres or operating theatres, 6% (n = 21).

Conclusion

Trauma remains a major indication for emergency blood transfusion in this setting. This study questions the use of emergency blood for certain non-urgent diagnoses (i.e. anaemia). Given the scarcity of this resource and limitations to access, appropriate use of emergency blood needs to be better defined locally. Ongoing monitoring of the indications for which emergency blood is used, improved transfusion stewardship and better systems to access emergency blood should be a priority in this setting.

Intra- and Postoperative Blood Loss and Transfusion Requirements in Children Undergoing Craniofacial Surgery

Pediatric craniosynostosis (CS) surgery is frequently associated with extensive blood loss and transfusion requirements. The aim of the study was to evaluate the authors' institutional procedure with 2-surgeon approach and early transfusion strategy on blood loss and blood product transfusions in children undergoing craniofacial surgery. A retrospective analysis of medical records was performed of pediatric CS corrections during a 15-year period. Primary endpoint was blood loss and transfusion requirement during and the following 24 hours postoperatively. Linear regression analyses were performed of associations between intra and- postoperative blood loss and blood loss and weight. A total of 276 children (median 9 months) were included. Intraoperative blood loss was 22 mL/kg (14-33 mL/kg) and postoperatively 27 mL/kg (18-37 mL/kg), with no change during the study period. Intraoperative transfusions of red blood cell and plasma were 16 mL/kg (10-24 mL/kg) and postoperative 14 mL/kg (9-21 mL/kg). Postoperative red blood cell and plasma transfusions were 2 mL/kg (0-6 mL/kg) and of 0 mL/kg, respectively. Craniosynostosis type was related to blood loss (P < 0.001). There was an association between intraoperative and postoperative blood loss (P = 0.012) and intra- and postoperative blood loss and weight (P = 0.002, P = < 0.001). Duration of surgery was 110 minutes (range 60-300 minutes).Pediatric CS surgery is associated with substantial intra- and postoperative blood loss and transfusion requirements, which did not change over a 15-year period. Blood loss was associated with type of CS. Intraoperative blood loss was correlated to postoperative blood loss and body weight.

Transfusion Camp: a prospective evaluation of a transfusion education program for multispecialty postgraduate trainees

BACKGROUND

The optimal method of providing transfusion medicine (TM) education has not been determined. Transfusion Camp was established in 2012 at the University of Toronto as a centrally delivered TM education program for postgraduate trainees. The impact of Transfusion Camp on knowledge, attitudes, and self-reported behavior was evaluated.

METHODS

Didactic lectures (delivered locally, by webinar, or recorded) and locally facilitated team-based learning seminars were delivered over 5 days during the academic year to 8 sites: 7 in Canada and 1 in the United Kingdom. Knowledge assessment using a validated 20-question multiple-choice exam was conducted before and after Transfusion Camp. Attitudes and self-reported behavior were collected through a survey.

RESULTS

Over 2 academic years (July 2016 to June 2018), 390 trainees from 16 different specialties (predominantly anesthesia, 41%; hematology, 14%; and critical care, 7%) attended at least 1 day of Transfusion Camp. The mean pretest score was 10.3 of 20 (±2.9; n = 286) compared with posttest score of 13.0 (±2.8; n = 194; p < 0.0001). Lower pretest score and greater attendance (4-5 days compared with 1-3 days) were associated with larger improvement in posttest score; delivery format, specialty, and postgraduate year were not. Trainees reported an improvement in self-rated abilities to manage TM scenarios; 95% rated TM knowledge as very or extremely important in providing patient care; and 81% indicated that they had applied learning from Transfusion Camp into clinical practice.

CONCLUSIONS

Transfusion Camp increased TM knowledge, fostered a positive attitude toward TM, and enabled a self-reported positive impact on transfusion practice in postgraduate trainees. It is a novel and scalable approach to delivering TM education.

Thromboelastography or rotational thromboelastometry for bleeding management in adults undergoing cardiac surgery: a systematic review with meta-analysis and trial sequential analysis

Background

Severe bleeding and massive transfusion of blood products may be associated with increased morbidity and mortality of cardiac surgery. A transfusion algorithm incorporating thromboelastography (TEG) or rotational thromboelastometry (ROTEM) can help to determine the appropriate time and target for the use of hemostatic blood products, which may thus reduce the quantity of blood loss as well as blood products transfused.

Methods

We conducted meta-analysis and trial sequential analysis to evaluate the effects of TEG or ROTEM-guided transfusion algorithms vs. standard treatments for patients undergoing cardiac surgery with cardiac pulmonary bypass.

Results

Nineteen studies with a total of 15,320 participants, including 13 randomized controlled trials (RCTs), were included. All-cause mortality was not reduced either in overall studies or in RCTs. Blood loss volume was reduced by 132 mL in overall studies [mean difference (MD): -132.46, 95% CI: -207.49, -57.43; I² =53%, P<0.01], and by 103 mL in RCTs (MD: -103.50, 95% CI: -156.52, -50.48; I² =0%, P<0.01). The relative risks (RRs) in RCTs were 0.89 (95% CI: 0.80-0.98; I² =0%, P=0.02) for red blood cells transfusion, 0.59 (95% CI: 0.42-0.82; I² =55%, P<0.01) for fresh frozen plasma transfusion, and 0.81 (95% CI: 0.74-0.90; I² =0%, P<0.01) for platelet transfusion, respectively. Trial sequential analysis of continuous data on blood loss and dichotomous outcomes on transfusion of blood products suggested the benefits of a TEG/ROTEM-guided algorithm.

Conclusions

TEG or ROTEM-guided transfusion strategies may reduce blood loss volume and the transfusion rates in adult patients undergoing cardiac surgery.

Intraoperativer Volumenersatz, Transfusion und Behandlung von Gerinnungsstörungen

Sowohl der operative Eingriff als auch die Narkose führen zu Veränderungen des intravasalen Volumenstatus des Patienten. Ziele der perioperativen Flüssigkeits- bzw. Volumentherapie sind die Aufrechterhaltung des zirkulierenden intravasalen Volumen (Normovolämie), einer adäquaten Gewebeperfusion und -oxygenierung, des Gleichgewichts im Elektrolythaushalt sowie die Aufrechterhaltung der Normoglykämie.

Red blood cell storage lesion: causes and potential clinical consequences

Red blood cells (RBCs) are a specialised organ that enabled the evolution of multicellular organisms by supplying a sufficient quantity of oxygen to cells that cannot obtain oxygen directly from ambient air via diffusion, thereby fueling oxidative phosphorylation for highly efficient energy production. RBCs have evolved to optimally serve this purpose by packing high concentrations of haemoglobin in their cytosol and shedding nuclei and other organelles. During their circulatory lifetimes in humans of approximately 120 days, RBCs are poised to transport oxygen by metabolic/redox enzymes until they accumulate damage and are promptly removed by the reticuloendothelial system. These elaborate evolutionary adaptions, however, are no longer effective when RBCs are removed from the circulation and stored hypothermically in blood banks, where they develop storage-induced damages ("storage lesions") that accumulate over the shelf life of stored RBCs. This review attempts to provide a comprehensive view of the literature on the subject of RBC storage lesions and their purported clinical consequences by incorporating the recent exponential growth in available data obtained from "omics" technologies in addition to that published in more traditional literature. To summarise this vast amount of information, the subject is organised in figures with four panels: i) root causes; ii) RBC storage lesions; iii) physiological effects; and iv) reported outcomes. The driving forces for the development of the storage lesions can be roughly classified into two root causes: i) metabolite accumulation/depletion, the target of various interventions (additive solutions) developed since the inception of blood banking; and ii) oxidative damages, which have been reported for decades but not addressed systemically until recently. Downstream physiological consequences of these storage lesions, derived mainly by in vitro studies, are described, and further potential links to clinical consequences are discussed. Interventions to postpone the onset and mitigate the extent of the storage lesion development are briefly reviewed. In addition, we briefly discuss the results from recent randomised controlled trials on the age of stored blood and clinical outcomes of transfusion.

Role of Thromboelastography and Rotational Thromboelastometry in the Management of Cardiovascular Diseases

The monitoring of coagulation by viscoelastometric methods—thromboelastography and rotational thromboelastometry—may detect the contributions of cellular and plasma components of hemostasis. These methods might overcome some of the serious limitations of conventional laboratory tests. Viscoelastic testing can be repeatedly performed during and after surgery and thus provides a dynamic picture of the coagulation process during these periods. Several experiences with the use of these methods in cardiovascular surgery have been reported, but there is perspective for more frequent use of these assays in the assessment of platelet response to antiplatelet therapy and in the assessment of coagulation in patients on long-term dabigatran therapy. This article reviews the current role and future perspectives of thromboelastography and thromboelastometry in the management of cardiovascular diseases.

Inherited platelet functional disorders: General principles and practical aspects of management

Platelets are a critical component for effecting hemostasis and wound healing. Disorders affecting any platelet pathway mediating adhesion, activation, aggregation and procoagulant surface exposure can result in a bleeding diathesis. Specific diagnosis even with advanced techniques which are unavailable to most centers is often difficult. Inherited platelet function disorders therefore represent a heterogeneous and complex collection of disorders with a spectrum of bleeding severity, from relatively mild (and easily missed or misdiagnosed) to severe bleeding phenotype with salient diagnostic features. We advocate the use of bleeding assessment tools to help identification of patients and more importantly for assessment of individual patient bleeding phenotype to guide management decisions for treating and preventing bleeding. The complex management of these patients is best coordinated in a multidisciplinary comprehensive care clinic setting expert in managing bleeding disorders and associated complications, with particular attention to the physical and psychosocial health of patients and their families. Depending on the bleeding phenotype, the location and severity of bleeding, and the nature of an invasive procedure, available treatment modalities range from conservative measures using local pressure, topical thrombin, fibrin sealant, antifibrinolytics etc. to the use of systemic haemostatics such as desmopressin (DDAVP), platelets and recombinant human activated factor VII (rFVIIa). This review will provide opinions on the practical aspects and general management of inherited platelet function disorders, with discussion on the mechanism of action, and the pros and cons of various hemostatic agents. Finally, the prospect of curative treatment for patients with severe bleeding phenotype refractory to available treatments and with poor quality of life will be briefly discussed.

Light-based methods for whole blood bacterial inactivation enabled by a recirculating flow system

Light of certain wavelengths can be used to inactivate pathogens. Whole blood is opaque; thus, the penetration of light is reduced. Here, we overcame this limitation using a thin transparent tube that is illuminated from all angles. Three light-based techniques were evaluated: photodynamic therapy (PDT) using a 660-nm light and antibody-photosensitizer conjugates, ultraviolet, and violet light. We observed a reduction of 55-71% of Staphylococcus aureus after 5 h of exposure (starting concentration 107  CFU mL-1 ) and an 88-97% reduction in methicillin-resistant Staphylococcus aureus (MRSA) (starting 104  CFU mL-1 ). An 83-92% decrease for S. aureus and 98-99.9% decrease for MRSA were observed when combined with an immunocapture approach. Complete blood count with differential analysis did not reveal any significant changes in the blood cell numbers. Genotoxicity studies showed that violet and ultraviolet did not induce any significant level of single strand breaks and alkali labile sites in the peripheral blood mononuclear cells (PBMC). In contrast, ultraviolet did induce a very low level of cyclobutane pyrimidine dimers, a UV damage indicator. PDT generated a significant level of single strand breaks and 8-oxoGua in these cells. The approaches showed promise for whole blood pathogen inactivation with minimal collateral damage to PBMC.

Pediatric red cell and platelet transfusions

The aim of pediatric transfusions should be based on the concept of avoiding unnecessary transfusions without jeopardizing the patient safety and providing correct blood components when there are well founded indications to transfuse. Despite considerable efforts from transfusion services to increase transfusion safety, transfusions are still associated with preventable and unpreventable adverse effects that may, in the worst case, have severe and fatal consequences. Transfusions to pediatric patients constitute a small proportion of all transfusions but have higher incidence of adverse events compared to adults. Pediatric transfusions consist of intrauterine transfusions, top-up transfusions to neonates and young children, exchange transfusions in the management of hemolytic disease of newborn (HDN), in addition to sickle cell crisis, chronic transfusion therapy in thalassemia patients, massive transfusion in trauma, HLA- and HPA-compatible platelets in immunized patients and neonates with fetal neonatal alloimmune thrombocytopenia (FNAIT). Packed red cells (PRCs) and platelet (PLT) concentrates are the most utilized blood components and will be reviewed here.

Risk perception of blood transfusions - a comparison of patients and allied healthcare professionals

Background

Due to an increasing demand in health care services plans to substitute selective physician-conducted medical activities have become attractive. Because administration of a blood transfusion is a highly standardized procedure, it might be evaluated if obtaining a patient’s consent for a blood transfusion can be delegated to allied healthcare professionals. Physicians and patients perceive risks of transfusions differently. However, it is unknown how allied healthcare professionals perceive risks of transfusion-associated adverse events.

Methods

Patients (n = 506) and allied healthcare professionals (n = 185) of an academic teaching hospital were asked to quantify their concerns about transfusions including five predefined transfusion-associated risks and their incidences.

Results

Blood transfusions were considered to be generally harmful by 10.9% of patients and 14.6% of caregivers (P = 0.180). Among all surveyed patients, 36.8% were worried about infection-transmissions (caregivers: 27.6%; P = 0.024). Compared to 5.4% of caregivers, 13.6% of patients believed infection-transmission was a frequent complication (P = 0.003). Caregivers ranked the risks of receiving an AB0-mismatch transfusion (caregivers: 29.7% vs. patients: 19.2%, P = 0.003) or a transfusion-associated allergic reaction (caregivers: 17.3% vs. patients: 11.1%, P = 0.030) significantly higher than patients and were aware of the high incidence of transfusion-associated fever (caregivers: 17.8% vs. patients: 8.3%, P < 0.001).

Conclusion

A significant part of interviewees perceived transfusions as a general health hazard. Patients perceived infection-transmissions as the most frequent and greatest transfusion-associated threat while caregivers focused on fatal AB0-mismatch transfusions and allergic reactions. Understanding the patients’ main concerns about blood transfusions and considering that these concerns might differ from the view of healthcare professionals might improve the process of shared decision making.

Electronic supplementary material

The online version of this article (10.1186/s12913-018-2928-x) contains supplementary material, which is available to authorized users.

Transfusion practice in anemic, non-bleeding patients: Cross-sectional survey of physicians working in general internal medicine teaching hospitals in Switzerland

Background

Transfusion practice might significantly influence patient morbidity and mortality. Between European countries, transfusion practice of red blood cells (RBC) greatly differs. Only sparse data are available on transfusion practice of general internal medicine physicians in Switzerland.

Methods

In this cross-sectional survey, physicians working in general medicine teaching hospitals in Switzerland were investigated regarding their self-reported transfusion practice in anemic patients without acute bleeding. The definition of anemia, transfusion triggers, knowledge on RBC transfusion, and implementation of guidelines were assessed.

Results

560 physicians of 71 hospitals (64%) responded to the survey. Anemia was defined at very diverging hemoglobin values (by 38% at a hemoglobin <130 g/L for men and by 57% at <120 g/L in non-pregnant women). 62% and 43% respectively, did not define anemia in men and in women according to the World Health Organization. Fifty percent reported not to transfuse RBC according to international guidelines. Following factors were indicated to influence the decision to transfuse: educational background of the physicians, geographical region of employment, severity of anemia, and presence of known coronary artery disease. 60% indicated that their knowledge on Transfusion-related Acute Lung Injury (TRALI) did not influence transfusion practice. 50% of physicians stated that no local transfusion guidelines exist and 84% supported the development of national recommendations on transfusion in non-acutely bleeding, anemic patients.

Conclusion

This study highlights the lack of adherence to current transfusion guidelines in Switzerland. Identifying and subsequently correcting this deficit in knowledge translation may have a significant impact on patient care.

Plasma Transfusion: History, Current Realities, and Novel Improvements

Traumatic hemorrhage is the leading cause of preventable death after trauma. Early transfusion of plasma and balanced transfusion have been shown to optimize survival, mitigate the acute coagulopathy of trauma, and restore the endothelial glycocalyx. There are a myriad of plasma formulations available worldwide, including fresh frozen plasma, thawed plasma, liquid plasma, plasma frozen within 24 h, and lyophilized plasma (LP). Significant equipoise exists in the literature regarding the optimal plasma formulation. LP is a freeze-dried formulation that was originally developed in the 1930s and used by the American and British military in World War II. It was subsequently discontinued due to risk of disease transmission from pooled donors. Recently, there has been a significant amount of research focusing on optimizing reconstitution of LP. Findings show that sterile water buffered with ascorbic acid results in decreased blood loss with suppression of systemic inflammation. We are now beginning to realize the creation of a plasma-derived formulation that rapidly produces the associated benefits without logistical or safety constraints. This review will highlight the history of plasma, detail the various types of plasma formulations currently available, their pathophysiological effects, impacts of storage on coagulation factors in vitro and in vivo, novel concepts, and future directions.

[Transfusion in elderly: Take account frailty]

The conjunction of the demographic aging and the increase in the frequency of anemia with the advancing age, mean that the number of globular concentrates delivered each year increases with a consequent heavy pressure on blood collection. The etiologies of anemia in the elderly are often multifactorial and their investigation is an indispensable step and prior to any treatment. Transfusion thresholds, particularly in the elderly, are gradually evolving and a so-called restrictive strategy is now favored. Immediate and delayed complications of transfusion are more frequent in the elderly due to vulnerability factors associated with frailty and the risk of multiple transfusions. The screening of complications related to transfusion of RBCs is essential and makes it possible to avoid their recurrence. The impact of transfusion on the quality of life of elderly patients is not obvious and is a controversial issue. In addition, transfusion of red blood cells (RBCs) is accompanied by an increase in health expenditure and an increase in morbidity and mortality, whose risks can be reduced through alternatives to transfusion. Longitudinal studies, including elderly subjects, would allow a better understanding of the issues involved in the transfusion of RBCs in this population.

Improved outcomes and reduced costs associated with a health-system-wide patient blood management program: a retrospective observational study in four major adult tertiary-care hospitals

BACKGROUND

Patient blood management (PBM) programs are associated with improved patient outcomes, reduced transfusions and costs. In 2008, the Western Australia Department of Health initiated a comprehensive health-system-wide PBM program. This study assesses program outcomes.

STUDY DESIGN AND METHODS

This was a retrospective study of 605,046 patients admitted to four major adult tertiary-care hospitals between July 2008 and June 2014. Outcome measures were red blood cell (RBC), fresh-frozen plasma (FFP), and platelet units transfused; single-unit RBC transfusions; pretransfusion hemoglobin levels; elective surgery patients anemic at admission; product and activity-based costs of transfusion; in-hospital mortality; length of stay; 28-day all-cause emergency readmissions; and hospital-acquired complications.

RESULTS

Comparing final year with baseline, units of RBCs, FFP, and platelets transfused per admission decreased 41% (p < 0.001), representing a saving of AU$18,507,092 (US$18,078,258) and between AU$80 million and AU$100 million (US$78 million and US$97 million) estimated activity-based savings. Mean pretransfusion hemoglobin levels decreased 7.9 g/dL to 7.3 g/dL (p < 0.001), and anemic elective surgery admissions decreased 20.8% to 14.4% (p = 0.001). Single-unit RBC transfusions increased from 33.3% to 63.7% (p < 0.001). There were risk-adjusted reductions in hospital mortality (odds ratio [OR], 0.72; 95% confidence interval [CI], 0.67-0.77; p < 0.001), length of stay (incidence rate ratio, 0.85; 95% CI, 0.84-0.87; p < 0.001), hospital-acquired infections (OR, 0.79; 95% CI, 0.73-0.86; p < 0.001), and acute myocardial infarction-stroke (OR, 0.69; 95% CI, 0.58-0.82; p < 0.001). All-cause emergency readmissions increased (OR, 1.06; 95% CI, 1.02-1.10; p = 0.001).

CONCLUSION

Implementation of a unique, jurisdiction-wide PBM program was associated with improved patient outcomes, reduced blood product utilization, and product-related cost savings.

The platelets' perspective to pathogen reduction technologies

A wide variety of clinical conditions, associated with low circulating platelet counts, require platelet transfusion in order to normalize hemostatic function. Although single-donor apheresis platelets bear the lowest risk of transfusion-transmitted infections, pathogen reduction technologies (PRT) are being implemented worldwide to reduce this risk further through inactivation of known, emergent and as yet to be discovered nucleic acid-based pathogens. Human blood platelets are now known to harbor a diverse transcriptome, important to their function and comprised of >5000 protein-coding messenger RNAs and different classes of non-coding RNAs, including microRNAs. Our appreciation of the nucleic acid-dependent functions of platelets is likely to increase. On the other hand, the side effects of PRT on platelet function are underappreciated. Recent evidences suggest that PRT may compromise platelets' responsiveness to agonists, and induce platelet activation. For instance, platelets have the propensity to release proinflammatory microparticles (MPs) upon activation, and the possibility that PRT may enhance the production of platelet MPs in platelet concentrates (PCs) appears likely. With this in mind, it would be timely and appropriate to investigate other means to inactivate pathogens more specifically, or to modify the currently available PRT so to better preserve the platelet function and improve the safety of PCs; platelets' perspective to PRT deserves to be considered.

Health Technology Assessment of pathogen reduction technologies applied to plasma for clinical use

Although existing clinical evidence shows that the transfusion of blood components is becoming increasingly safe, the risk of transmission of known and unknown pathogens, new pathogens or re-emerging pathogens still persists. Pathogen reduction technologies may offer a new approach to increase blood safety. The study is the output of collaboration between the Italian National Blood Centre and the Post-Graduate School of Health Economics and Management, Catholic University of the Sacred Heart, Rome, Italy. A large, multidisciplinary team was created and divided into six groups, each of which addressed one or more HTA domains.Plasma treated with amotosalen + UV light, riboflavin + UV light, methylene blue or a solvent/detergent process was compared to fresh-frozen plasma with regards to current use, technical features, effectiveness, safety, economic and organisational impact, and ethical, social and legal implications. The available evidence is not sufficient to state which of the techniques compared is superior in terms of efficacy, safety and cost-effectiveness. Evidence on efficacy is only available for the solvent/detergent method, which proved to be non-inferior to untreated fresh-frozen plasma in the treatment of a wide range of congenital and acquired bleeding disorders. With regards to safety, the solvent/detergent technique apparently has the most favourable risk-benefit profile. Further research is needed to provide a comprehensive overview of the cost-effectiveness profile of the different pathogen-reduction techniques. The wide heterogeneity of results and the lack of comparative evidence are reasons why more comparative studies need to be performed.

Bridging channel dendritic cells induce immunity to transfused red blood cells

Calabro et al. show that 33D1⁺ dendritic cells present in the bridging channel of the spleen are essential for alloantibody response to transfused red blood cells.

Red blood cell (RBC) transfusion is a life-saving therapeutic tool. However, a major complication in transfusion recipients is the generation of antibodies against non-ABO alloantigens on donor RBCs, potentially resulting in hemolysis and renal failure. Long-lived antibody responses typically require CD4⁺ T cell help and, in murine transfusion models, alloimmunization requires a spleen. Yet, it is not known how RBC-derived antigens are presented to naive T cells in the spleen. We sought to answer whether splenic dendritic cells (DCs) were essential for T cell priming to RBC alloantigens. Transient deletion of conventional DCs at the time of transfusion or splenic DC preactivation before RBC transfusion abrogated T and B cell responses to allogeneic RBCs, even though transfused RBCs persisted in the circulation for weeks. Although all splenic DCs phagocytosed RBCs and activated RBC-specific CD4⁺ T cells in vitro, only bridging channel 33D1⁺ DCs were required for alloimmunization in vivo. In contrast, deletion of XCR1⁺CD8⁺ DCs did not alter the immune response to RBCs. Our work suggests that blocking the function of one DC subset during a narrow window of time during RBC transfusion could potentially prevent the detrimental immune response that occurs in patients who require lifelong RBC transfusion support.