Maternal and child life years gained by transfusing low titer group O whole blood in trauma: A computer simulation.

BACKGROUND: Using low titer group O whole blood (LTOWB) is increasingly popular for resuscitating trauma patients. LTOWB is often RhD-positive, which might cause D-alloimmunization and hemolytic disease of the fetus and newborn (HDFN) if transfused to RhD-negative females of childbearing potential (FCP). This simulation determined the number of life years gained by the FCP and her future children if she was resuscitated with LTOWB compared with conventional component therapy (CCT). METHODS: The model simulated 500,000 injured FCPs of each age between 0 and 49 years with LTOWB mortality relative reductions (MRRs) compared with components between 0.1% and 25%. For each surviving FCP, number of life years gained was calculated using her age at injury and average life expectancy for American women. The number of expected future pregnancies for FCPs that did not survive was also based on her age at injury; each future child was assigned the maximum lifespan unless they suffered perinatal mortality or serious neurological events from HDFN. RESULTS: The LTOWB group with an MRR 25% compared with CCT had the largest total life years gained. The point of equivalence for RhD-positive LTOWB compared to CCT, where life years lost due to severe HDFN was equivalent to life years gained due to FCP survival/future childbearing, occurred at an MRR of approximately 0.1%. CONCLUSION: In this model, RhD-positive LTOWB resulted in substantial gains in maternal and child life years compared with CCT. A >0.1% relative mortality reduction from LTOWB offset the life years lost to HDFN mortality and severe neurological events.

Low titer group O whole blood and risk of RhD alloimmunization: Rationale for use in Finland.

BACKGROUND: Prehospital low-titer group O whole blood (LTOWB) used for patients with life-threatening hemorrhage is often RhD positive. The most important complication following RhD alloimmunization is hemolytic disease of the fetus and newborn (HDFN). Preceding clinical use of RhD positive LTOWB, we estimated the risk of HDFN due to LTOWB prehospital transfusion in the Finnish population. STUDY DESIGN AND METHODS: We collected data on prehospital transfusions in Tampere and Helsinki University Hospital areas. Using the mean of reported alloimmunization rates in trauma studies (24%) and a higher reported rate representing trauma patients of 13-50 years old (42.7%), we estimated the risk of HDFN and extrapolated it to the whole of Finland. RESULTS: We estimated that in Finland, with the current prehospital transfusion rate we would see 1-3 cases of severe HDFN due to prehospital LTOWB transfusions every 10 years, and fetal death due to HDFN caused by LTOWB transfusion less than once in 100 years. DISCUSSION: The estimated risk of serious HDFN due to prehospital LTOWB transfusion in the Finnish population is similar to previous estimates. As Finland routinely screens expectant mothers for red blood cell antibodies and as the contemporary treatment of HDFN is very effective, we support the prehospital use of RhD positive LTOWB in all patient groups.

Deploying whole blood to the battlefield-The Israel Defense Forces Medical Corps initial experience during the 2023 war.

BACKGROUND: Military and prehospital medical organizations invest significant resources to advance the treatment of trauma patients aiming to reduce preventable deaths. Focus is on hemorrhage control and volume resuscitation with blood products, with adoption of Remote Damage Control Resuscitation (RDCR) guidelines. The Israel Defense Forces Medical Corps (IDF-MC) has been using tranexamic acid and freeze-dried plasma (FDP) as part of its RDCR protocol for more than a decade. In recent years, low-titer group O whole blood (LTOWB) has been integrated, on IDF evacuation helicopters and expanded to mobile ambulances, complementing FDP use in treating trauma patients in state of profound shock. STUDY DESIGN AND METHODS: During the war that erupted in October 2023, the IDF-MC made a decision to bring LTOWB forward, and to equip every combat brigade level mobile intensive care units with LTOWB, onboard armored vehicles. The goal was to make whole blood available as close as possible to the point of injury and within minutes from time of injury. RESULTS AND DISCUSSION: We describe the IDF-MCs' efforts to bring LTOWB to the front lines and present four cases in which LTOWB was administered. All patients were young male, with significant blood loss following penetrating injuries. One patient died in the operating room, following hospital arrival and emergency thoracotomy. The others survived. Our initial experience with bringing LTOWB as close as possible to the point of injury during high intensity fighting is encouraging, showing patient benefit along with logistic feasibility. After action reports and data collection will continue.

Receipt of RhD-positive whole blood for life-threatening bleeding in female children: A survey in alloimmunized mothers regarding minimum acceptable survival benefit relative to risk of maternal alloimmunization to anti-D.

BACKGROUND: Low-titer group O whole blood (LTOWB) for treatment of hemorrhagic shock sometimes necessitates transfusion of RhD-positive units due to short supply of RhD-negative LTOWB. Practitioners must choose between using RhD-positive LTOWB when RhD-negative is unavailable against the risk to a female of childbearing potential of becoming RhD-alloimmunized, risking hemolytic disease of the fetus and newborn (HDFN) in future children, or using component therapy with RhD-negative red cells. This survey asked females with a history of red blood cell (RBC) alloimmunization about their risk tolerance of RhD alloimmunization compared to the potential for improved survival following transfusion of RhD-positive blood for an injured RhD negative female child. STUDY DESIGN AND METHODS: A survey was administered to RBC alloimmunized mothers. Respondents were eligible if they were living in the United States with at least one red cell antibody known to cause HDFN and if they had at least one RBC alloimmunized pregnancy. RESULTS: Responses from 107 RBC alloimmmunized females were analyzed. There were 32/107 (30%) with a history of severe HDFN; 12/107 (11%) had a history of fetal or neonatal loss due to HDFN. The median (interquartile range) absolute improvement in survival at which the respondents would accept RhD-positive transfusions for a female child was 4% (1%-14%). This was not different between females with and without a history of severe or fatal HDFN (p = .08 and 0.38, respectively). CONCLUSION: Alloimmunized mothers would accept the risk of D-alloimmunization in a RhD-negative female child for improved survival in cases of life-threatening bleeding.

Impact of ABO blood group on mortality in trauma patients: A systematic review.

BACKGROUND: Haemorrhage is a significant cause of death in trauma patients. There is evidence that individuals with blood group O have higher rates of non-traumatic haemorrhage. It has been suggested that blood group O may be associated with higher mortality in trauma, however existing evidence is limited and conflicting. OBJECTIVE: A systematic review was conducted to evaluate the impact of ABO blood group on mortality in trauma patients. METHODS: MEDLINE via OVID, the Cochrane library and grey literature were searched to identify studies investigating the effect of ABO blood group on mortality of trauma patients admitted to hospital. PRISMA guidelines were followed throughout, study quality was assessed using CASP checklists and certainty of evidence was evaluated using GRADE. Meta-analysis was precluded by significant study heterogeneity. RESULTS: 180 relevant records were screened and seven studies met inclusion criteria, representing 12,240 patients. Two studies found that there was a higher mortality in blood group O compared to other ABO groups. Included studies had substantial variability in methods and population. Study quality was variable with certainty of evidence rated as very low. CONCLUSIONS: There is insufficient evidence to definitively establish an association between mortality and ABO group in trauma patients. In an age of increasingly individualised care, there is a need to determine the existence and cause for any association through further studies across multiple settings, trauma mechanisms and populations.

Transfusion of ABO-group identical red blood cells following uncrossmatched transfusion does not lead to higher mortality in civilian trauma patients.

BACKGROUND: Questions persist about the safety of switching non-group O recipients of group O uncrossmatched red blood cells (RBC) or low titer group O whole blood (LTOWB) to ABO-identical RBCs during their resuscitation. METHODS: The database of an earlier nine-center study of transfusing incompatible plasma to trauma patients was reanalyzed. The patients were divided into three groups based on 24-h RBC transfusion: (1) group O patients who received group O RBC/LTOWB units (control group, n = 1203), (2) non-group O recipients who received only group O units (n = 646), (3) non-group O recipients who received at least one unit of group O and non-group O units (n = 562). Fixed marginal effect of receipt of non-O RBC units on 6- and 24-h and 30-day mortality was calculated. RESULTS: The non-O patients who received only group O RBCs received fewer RBC/LTOWB units and had slightly but significantly lower injury severity score compared to control group; non-group O patients who received both group O and non-O units received significantly more RBC/LTOWB units and had a slightly but significantly higher injury severity score compared to control group. In the multivariate analysis, the non-O patients who received only group O RBCs had significantly higher mortality at 6-h compared to the controls; the non-group O recipients of O and non-O RBCs did not demonstrate higher mortality. At 24-h and 30-days, there were no differences in survival between the groups. CONCLUSION: Providing non-group O RBCs to non-group O trauma patients who also received group O RBC units is not associated with higher mortality.

Delayed Leukoreduction of whole blood with a platelet-sparing filter to increase low-titer group O whole blood production in the United States.

BACKGROUND: Demand for low-titer Group O whole blood (LTOWB) is increasing for trauma. The whole blood (WB) platelet-sparing (WB-SP) filter enables leukoreduction (LR) while retaining platelet quantity and function; however, in the United States WB must be filtered and placed in the cold within 8 h of collection. A longer processing window would facilitate improved logistics and supply of LR-WB to meet the growing medical need. This study evaluated the impact of increasing filtration timing from <8 h to <12 h on the quality of LR-WB. STUDY DESIGN AND METHODS: Thirty WB units were collected from healthy donors. Control units were filtered within 8 h and test units within 12 h of collection. WB was tested throughout 21 days of storage. Hemolysis, WBC content, component recovery, and 25 additional markers of WB quality were tested including hematologic and metabolic markers, RBC morphology, aggregometry, thromboelastography, and p-selectin. RESULTS: There were 0 failures for residual WBC content, hemolysis, or pH, and no differences in component recovery between arms. Few differences in metabolic parameters were observed, but the small effect size suggests these are not clinically significant. Trends throughout storage were similar and filtration timing did not impact hematological parameters, platelet activation and aggregation, or hemostatic capacity. CONCLUSION: Our studies showed that extending filtration timing from 8 to 12 h from the collection does not significantly impact the quality of LR-WB. Characterization of the platelets demonstrated that storage lesions were not exacerbated. Extending the time from collection to filtration will improve LTOWB inventory in the United States.

Emergency transfusion with whole blood versus packed red blood cells: A study of 1400 patients.

BACKGROUND: Low-titer group O whole blood (LTOWB) is increasingly used for emergency transfusion. We studied whether initial release of LTOWB compared with packed red blood cells (pRBCs) reduced overall blood requirements for patients needing emergency transfusion. Secondary outcomes examined included survival and non-lethal adverse clinical outcomes. STUDY DESIGN AND METHODS: A retrospective, single-center, before-versus-after study compared patients transfused with emergency-release, uncrossmatched pRBC followed by component therapy (2016-2019) versus patients transfused with emergency-release, uncrossmatched LTOWB followed by component therapy (2019-2022). RESULTS: Outcomes were available for 602 patients in the pRBC group versus 749 in the whole blood group. The two groups were similar for age, sex, race, estimated blood volume, ABO blood groups, and underlying diagnosis. Use of LTOWB was associated with increased blood product use at 24 h (4.0 (2.0-12.0) in pRBC group versus 6.5 (4.2-12.7) in LTOWB group, p < .0001) and at 7 days (5.5 (3.0-13.0) in pRBC group versus 7.3 (4.3-14.3) in LTOWB group, p < .0001). Initial use of LTOWB was not associated with improved 24 h or 30 day survival nor lower incidence of non-lethal adverse clinical outcomes compared with pRBC. DISCUSSION: Our study showed a statistically significant increase in total blood use and blood acquisition costs for patients receiving initial emergency transfusion with LTOWB compared with pRBC. The initial use of LTOWB offered no advantage over component therapy for 30 day survival or selected non-lethal adverse outcomes.

Receipt of low titer group O whole blood does not lead to hemolysis in children weighing less than 20 kilograms.

OBJECTIVE: The safety of Low Titer Group O Whole Blood (LTOWB) transfusion has not been well-studied in small children. METHODS: This is a single-center retrospective cohort study of pediatric recipients of RhD-LTOWB (June 2016-October 2022) who weigh less than 20 kilograms. Biochemical markers of hemolysis (lactate dehydrogenase, total bilirubin, haptoglobin, and reticulocyte count) and renal function (creatinine and potassium) were recorded on the day of LTOWB transfusion and post-transfusion days 1 and 2. Group O and non-Group O recipients were compared. RESULTS: Twenty-one children were included. Their median (interquartile range [IQR]) weight was 12 kg (12-18) with minimum 2.8 kg, and median (IQR) age was 3 years (1.75-5.00) with minimum 0.08 years (29 days old). The most common indication for transfusion was trauma (17/21; 81%). The median (IQR) volume of LTOWB transfused was 30 mL/kg (20-42). There were 9 non-group O and 12 group O recipients. There were no statistically significant differences in the median concentrations of any of the biochemical markers of hemolysis or the renal function markers between the non-group O and the group O recipients at any of the three time points (p > 0.05 for all comparisons). There were also no statistically significant differences in demographic parameters or clinical outcomes including 28-day mortality, length of stay, ventilator days, and venous thromboembolism between the groups. No transfusion reactions were reported in either group. CONCLUSION: These data suggest LTOWB use is safe in children weighing less than 20 kg. Further multi-center studies and larger cohorts are needed to confirm these results.

Timing of RhD-positive red blood cell administration is associated with D-alloimmunization in injured patients.

BACKGROUND: The D-alloimmunization rate in trauma patients does not appear to depend on the number of RhD-positive units transfused. The effect of the timing and pattern of RhD-positive transfusions has not been evaluated. METHODS: RhD-negative trauma patients who were transfused with RhD-positive red blood cells (RBC) or low titer group O whole blood (collectively called RBCs) on at least two separate calendar days and who had antibody detection tests performed at least 14 days after the second RhD-positive RBC transfusion without receiving RhIg were included in the analysis. Patients whose anti-D was detected within 14 days of the index RhD-positive RBC transfusion were excluded. Patient demographics and the dates of RhD-positive RBC transfusions and results of antibody detection tests performed after the index transfusion were collected on eligible patients. RESULTS: There were 44/61 (72.1%) patients in whom anti-D was not detected (non-alloimmunized) and 17/61 (27.9%) in whom anti-D was detected (alloimmunized). The patients had similar demographics with trends towards higher median admission heart rates and lower median admission Glasgow Coma Scale values in the alloimmunized group. Both groups received statistically identical median quantities of RhD-positive RBCs (non-alloimmunized 5 vs. alloimmunized 4 units, p = .53), however, the alloimmunized group received all their RhD-positive RBCs over a significantly shorter period of time compared to the non-alloimmunized (median 4 vs. 15 days, respectively, p = .01). CONCLUSION: Receipt of all RhD-positive RBCs over a shorter period of time was associated with higher D-alloimmunization rates. These results need to be confirmed in larger studies.

A rapid ABO and RhD test demonstrates high fidelity to blood bank testing for RhD typing.

BACKGROUND: The rapid provision of blood products is life-saving for patients with massive hemorrhage. Ideally, RhD-negative blood products would be supplied to a woman of childbearing potential whose Rh type is unknown due to the risk of D-alloimmunization and the potential for hemolytic disease of the fetus and newborn to occur if RhD-positive blood products are transfused. Therefore, there is a need for a test that rapidly determines her RhD type. This study compared the RhD type determined using a rapid ABO and RhD test to the RhD type determined by an immunohematology reference laboratory. METHODS: After receiving ethics review board approval, 200 random, unique, deidentified patient samples that had undergone routine pretransfusion testing in an immunohematology reference laboratory using column agglutination technology were collected and tested using a rapid ABO and RhD test (Eldoncard Home kit 2511). The RhD typing results from these two methods were compared to determine the accuracy of the rapid ABO and RhD test. RESULTS: The rapid ABO and RhD test produced results that were concordant with the transfusion service's results in 199/200 (99.5%) of cases, with a negative predictive value of 98.2% and 99.3% sensitivity. The single outlier was likely an RhD variant due to its serological characteristics. DISCUSSION: These data indicate that this rapid ABO and RhD test could be used for the rapid determination of a patient's RhD type, perhaps even in the emergency department, which could guide the selection of blood products provided during their resuscitation.

Low-titer group O whole blood in military ground ambulances: Lessons from the Israel Defense Forces initial experience.

BACKGROUND: Cold-stored low-titer group O whole blood (LTOWB) has become increasingly utilised in both prehospital and in-hospital settings for resuscitation of traumatic haemorrhage. However, implementing the use of LTOWB to ground medical teams has been limited due to logistic challenges. METHODS: In 2022, the Israel Defense Forces (IDF) started using LTOWB in ambulances for the first time in Israel. This report details the initial experience of this rollout and presents a case-series of the first patients treated with LTOWB. RESULTS: Between January-December 2022, seven trauma patients received LTOWB administered by ground IDF intensive care ambulances after presenting with profound shock. Median time from injury to administration of LTOWB was 35 min. All patients had evidence of severe bleeding upon hospital arrival with six undergoing damage control laparotomy and all but one surviving to discharge. CONCLUSIONS: The implementation of LTOWB in ground medical units is in its early stages, but continued experience may demonstrate its feasibility, safety, and effectiveness in the prehospital setting. Further research is necessary to fully understand the indications, methodology, and benefits of LTOWB in resuscitating severely injured trauma patients in this setting.

Receipt of at least 4 units of low titer group O whole blood with titer <100 does not lead to hemolysis in adult trauma patients.

BACKGROUND: The serological safety of transfusing low titer group O whole blood (LTOWB) with an anti-A and anti-B titer of <100 was evaluated in group O and non-group O trauma recipients. METHODS: Civilian adult trauma patients who received ≥4 units of leukoreduced LTOWB during their initial resuscitation and who survived for >24 h after admission at two level 1 trauma centers were included in this retrospective study. Lactate dehydrogenase (LDH), total bilirubin, haptoglobin, potassium, creatinine were evaluated on the day of LTOWB transfusion (day 0) and on the next 3 days. RESULTS: There were 77 injured recipients evaluated: 39 non-group O and 38 group O. The median (IQR) number of transfused LTOWB units was 4 (4-6) and 4 (4-5), respectively, and the maximum number of units was 8 and 11, respectively. The non-group O patients received a median (IQR) volume of 1710 ml (1368-2070) of ABO-incompatible plasma. Comparing non-group O to group O recipients, there were no significant differences in the median haptoglobin, LDH, or creatinine concentrations at any time point. The median concentration of total bilirubin was significantly higher amongst the non-group O recipients on days 1 and 2, while on day 0 the median potassium concentration was significantly higher amongst the group O recipients. All median elevated values were within the laboratory's normal range. Amongst the non-group O recipients there were no reported transfusion reactions. CONCLUSION: Receiving at least four LTOWB units (anti-A&B titer <100) was not associated with biochemical/clinical evidence of hemolysis in adult trauma patients.

Hyperbaric effects on cold stored whole blood following a military dive mission profile.

BACKGROUND: Whole blood (WB) is carried by special operations forces as part of a remote damage control resuscitation strategy. The effects of an underwater mission on the quality and coagulation profile of WB were simulated by exposure to hyperbaric pressures in a chamber. METHODS: WB units collected in CPDA-1 were exposed to three different combinations of hyperbaric pressure and duration of exposure: Group A 153.52 kPa (15.24 msw; 1.52 atm) for 4 h; n = 9, Group B 506.63 kPa (50.29 msw; 5.00 atm) for 1 h; n = 9, Group C 153.52 kPa (15.24 msw; 1.52 atm) for 1 h; n = 7. The following parameters were measured on each unit: prothrombin time/international normalized ratio, activated partial thromboplastin time, thromboelastography and concentration determinations of platelets, lactate, fibrinogen, and lactate dehydrogenase. Each sample underwent baseline, prepressurization, immediate postpressurization, and 6 h postpressurization laboratory testing. RESULTS: Six hours following hyperbaric exposure, the lactate concentration in group C was higher than prepressurization measurement and the platelet concentration in Group A was lower than prepressurization measurement. There were no changes in any of the other analyzed biochemical, coagulation and thromboelastogram parameters following exposure to hyperbaric stress. DISCUSSION: These data suggest that pressurization of WB up to 5 atm did not impact parameters tested. Changes observed in lactate and platelet count need further study, as well as complementary testing of red blood cell integrity. Further investigation of the hyperbaric extremes is necessary to determine if there is a damage inducing pressure to which WB should not be exposed.

Attitudes of American adult women toward accepting RhD-mismatched transfusions in bleeding emergencies.

BACKGROUND: There is an increasing literature demonstrating the benefits of prehospital and early in-hospital transfusions. RhD-positive products might only be available during these phases, which could pose consequences for future pregnancies if D-alloimmunization occurs. This survey measured the willingness of females to accept urgent but incompatible transfusions in light of the potential for future pregnancy complications. METHODS: A survey was designed to assess the willingness of females ≥18 years of age to accept urgent incompatible transfusions when different absolute risk reductions in maternal mortality were presented along with a static rate of 0.3%-4.0% risk of harm to future pregnancies. The survey was sent electronically to women who are part of the Washington University Research Enhancement Core database. RESULTS: A total of 4896 delivered survey email invitations were distributed and 325 (6.6%) responses were received; 16 responses were excluded leaving 309 responses for analysis. Most of the responding women were White, college-educated, and lived in Missouri. At least 90% of the respondents would accept an urgent incompatible transfusion when the absolute risk reduction in maternal mortality was ≥4%. Women without a college degree, who lived in Illinois, who were not able to have children appeared to be less willing than their counterparts to receive an incompatible transfusion when the absolute risk reduction in maternal mortality was low. CONCLUSION: This survey demonstrated that adult women are highly likely to be open to accept urgent incompatible blood transfusions during a bleeding emergency when the absolute risk reduction in maternal mortality was ≥4%.

The U.S. Armed Services Blood Program support to U.S. Central Command 2014-2021: Transformation of combat trauma resuscitation through blood product innovation and expansion of blood availability far forward.

BACKGROUND: The United States Armed Services Blood Program (ASBP) faced complex blood supply challenges during two decades of military operations in the U.S. Central Command (CENTCOM) and through an adaptive, responsive, and agile system, gained valuable insights on blood product usage in combat casualty care. STUDY DESIGN AND METHODS: A retrospective review of blood product introduction and utilization trends was compiled from ASBP data collected during CENTCOM operations from 2014 through 2021. RESULTS: During the study period, several blood products were introduced to the CENTCOM area of operations including Low Titer O Whole Blood (LTOWB), Cold-Stored Platelets (CSP), Liquid Plasma (LP), and French Freeze Dried Plasma (FDP) manufactured from U.S. sourced donor plasma, all while expanding Walking Blood Bank capabilities. There was a gradual substitution of component therapy for whole blood; blood utilization peaked in 2017. Transfusion of Fresh Whole Blood (FWB) from Walking Blood Banks decreased as fully pre-tested LTOWB was supplied by the ASBP. LTOWB was initially supplied in citrate-phosphate-dextrose (CPD) anticoagulant (21-day shelf life) but was largely replaced with LTOWB in citrate-phosphate-dextrose-adenine (CPDA-1) anticoagulant (35-day shelf life) by 2019. Implementation of prehospital transfusion and expansion of surgical and resuscitation teams led to an increase in the number of sites receiving blood. DISCUSSION: ASBP introduced new products to its inventory in order to meet changing blood product demands driven by changes in the Joint Trauma System Clinical Practice Guidelines and operational demands. These products were adopted into clinical practice with a resultant evolution in transfusion strategies.

Estimating the risks of prehospital transfusion of D-positive whole blood to trauma patients who are bleeding in England.

BACKGROUND AND OBJECTIVES: D-negative red cells are transfused to D-negative females of childbearing potential (CBP) to prevent haemolytic disease of the foetus and newborn (HDFN). Transfusion of low-titre group O whole blood (LTOWB) prehospital is gaining interest, to potentially improve clinical outcomes and for logistical benefits compared to standard of care. Enhanced donor selection requirements and reduced shelf-life of LTOWB compared to red cells makes the provision of this product challenging. MATERIALS AND METHODS: A universal policy change to the use of D-positive LTOWB across England was modelled in terms of risk of three specific harms occurring: risk of haemolytic transfusion reaction now or in the future, and the risk of HDFN in future pregnancies for all recipients or D-negative females of CBP. RESULTS: The risk of any of the three harms occurring for all recipients was 1:14 × 103 transfusions (credibility interval [CI] 56 × 102 -42 × 103 ) while for females of CBP it was 1:520 transfusions (CI 250-1700). The latter was dominated by HDFN risk, which would be expected to occur once every 5.7 years (CI 2.6-22.5). We estimated that a survival benefit of ≥1% using LTOWB would result in more life-years gained than lost if D-positive units were transfused exclusively. These risks would be lower, if D-positive blood were only transfused when D-negative units are unavailable. CONCLUSION: These data suggest that the risk of transfusing RhD-positive blood is low in the prehospital setting and must be balanced against its potential benefits.

The heart transplant allocation change attenuates but does not eliminate blood group O waitlist outcome disadvantage.

BACKGROUND: Patients with blood group O have historically been disadvantaged in the United Network for Organ Sharing (UNOS) heart transplant allocation system. We sought to determine whether the new UNOS allocation system implemented in 2018 had an impact on waitlist and post-transplant outcomes among blood groups. METHODS: Using the UNOS database we included all adult patients listed and transplanted with first-time single-organ heart transplant between 10/17/15 and 10/1/21. For post-transplant outcomes, we separately evaluated all adult patients transplanted with the same time-frame. We used exclusion criteria and censoring to limit biases from changing clinical practices around the allocation change (10/18/2018), and from unequal or inadequate follow-up. We compared clinical characteristics and outcomes before and after the allocation change among each blood group. Fine-Gray and Cox regression models were used to estimate the effect of the new allocation system on competing waitlist outcomes- transplantation, death-or-removal from waitlist- and post-transplant survival, respectively. RESULTS: Of the 21,565 patients listed for transplantation 14,000 met criteria for waitlist analysis (7,035 in the old system vs. 6,965 in the new), and 7,657 met criteria for post-transplant analysis (3,519 in the old system vs. 4,138 in the new). Among each blood group, new allocation change was associated with higher transplantation rates lower waitlist days and lower waitlist mortality (except Group AB). However, despite improvements, Group O was still associated with worse waitlist outcomes for each metric compared to non-O Groups. The new allocation system did not have a significant impact on post-transplant survival among any blood groups. CONCLUSION: Changes in heart transplant allocation have attenuated but not eliminated blood group O disadvantage in access to donor hearts.

Safety profile of low-titer group O whole blood in pediatric patients with massive hemorrhage.

BACKGROUND: Low-titer Group O Whole Blood (LTOWB) is used with increasing frequency in adult and pediatric trauma and massive bleeding transfusion protocols. There is a risk of acute hemolytic reactions in non-group O recipients due to the passive transfusion of anti-A and anti-B in the LTOWB. This study investigated the hemolysis risk among pediatric recipients of LTOWB. STUDY DESIGN AND METHODS: Blood bank records were queried for pediatric recipients of LTOWB between June 2016 and August 2020 and merged with clinical data. The primary outcome was laboratory evidence of hemolysis as manifested by changes in lactate dehydrogenase (LDH), haptoglobin, total bilirubin, reticulocyte count, potassium, and creatinine. Per protocol, these values were collected on hospital days 0-2 for recipients of LTOWB. Transfusion reactions were reported to the hospital's blood bank. RESULTS: Forty-seven children received LTOWB transfusion between 2016 and 2020; 21 were group O and 26 were non-group O. The groups were comparable in terms of the total volume of transfused blood products, demographics, and clinical outcomes. The most common indication for LTOWB transfusion was hemorrhagic shock due to trauma. There were no clinically or statistically significant differences in baseline, post-transfusion day 1, or post-transfusion day 2 hemolysis markers between the group O and non-group O LTOWB recipients. There were no adverse events or transfusion reactions reported. DISCUSSION: Use of up to 40 ml/kg of LTOWB appears to be serologically safe for children in hemorrhagic shock.

Survey of group A plasma and low-titer group O whole blood use in trauma resuscitation at adult civilian level 1 trauma centers in the US.

BACKGROUND: Recently revisited products like low-titer group O whole blood (LTOWB) and novel applications of group A as a universal donor of plasma are being used for trauma resuscitation. A survey of American Level 1 trauma centers was performed to elucidate the extent to which these products are currently employed. METHODS: A survey was written that probed into the current use of blood products in trauma resuscitation with specific emphasis on LTOWB and group A plasma. A list of adult civilian Level 1 trauma centers in the continental USA was obtained from two public surgery and trauma focused websites. An email was then sent to each center's transfusion service medical director or laboratory manager providing them with a link to the online survey. RESULTS: Responses were received from 103/187 (55%) adult civilian Level 1 trauma centers. For the resuscitation of trauma patients, group A plasma was used at 94/103 (91%) centers, while LTOWB was used at 43/103 (42%) centers. There were 39/103 (38%) centers that used both products. At 62/94 (66%) of the centers that used group A plasma, there was no limit on the number of units that could be administered, while an unlimited number of LTOWB units could be used at 5/43 (12%) of the centers that used LTOWB. RhD-positive LTOWB could be transfused to RhD-negative or RhD-type unknown females of childbearing potential at 22/43 (51%) of centers. CONCLUSION: The use of group A plasma and LTOWB in trauma is increasing at American Level 1 trauma centers.