Whole Blood and Blood Component Resuscitation in Trauma: Interaction and Association with Mortality.

OBJECTIVE: Evaluate the interaction between whole blood (WB) and blood component resuscitation in relation to mortality following trauma. SUMMARY BACKGROUND DATA: WB is increasingly available in civilian trauma resuscitation, and it is typically transfused concomitantly with blood components. The interaction between WB and blood component transfusions is unclear. METHODS: Adult trauma patients with a shock index >1 who received ≥4 combined units of red blood cells (RBC) or WB within 4 hours across 501 United States trauma centers were included using the American College of Surgeons Trauma Quality Improvement Program (ACS-TQIP) database. The associations between 1)WB resuscitation and mortality, 2)WB to total transfusion volume ratio (WB:TTV) and mortality, 3)balanced blood component transfusion in the setting of combined WB and component resuscitation and mortality were evaluated with multivariable analysis. RESULTS: A total of 12,275 patients were included (WB: 2,884 vs. component-only: 9,391). WB resuscitation was associated with lower odds of 4-hour (adjusted odds ratio [aOR]: 0.81 [0.68-0.97]), 24-hour, and 30-day mortality compared to component-only. Higher WB:TTV ratios were significantly associated with lower 4-hour, 24-hour, and 30-day mortality, with a 13% decrease in odds of 4-hour mortality for each 10% increase in the WB:TTV ratio (0.87 [95%CI:0.80 - 0.94]). Balanced blood component transfusion was associated with significantly lower odds of 4-hour (aOR: 0.45 [95%CI: 0.29 - 0.68]), 24-hour, and 30-day mortality in the setting of combined WB and blood component resuscitation. CONCLUSIONS: WB resuscitation, higher WB:TTV ratios, and balanced blood component transfusion in conjunction with WB were associated with lower mortality in trauma patients presenting in shock requiring 4 units of RBC and/or WB transfusion within 4 hours of arrival.

Early Cold Stored Platelet Transfusion Following Severe Injury: A Randomized Clinical Trial.

OBJECTIVE: To determine the feasibility, efficacy, and safety of early cold stored platelet transfusion compared with standard care resuscitation in patients with hemorrhagic shock. BACKGROUND: Data demonstrating the safety and efficacy of early cold stored platelet transfusion are lacking following severe injury. METHODS: A phase 2, multicenter, randomized, open label, clinical trial was performed at 5 US trauma centers. Injured patients at risk of large volume blood transfusion and the need for hemorrhage control procedures were enrolled and randomized. The intervention was the early transfusion of a single apheresis cold stored platelet unit, stored for up to 14 days versus standard care resuscitation. The primary outcome was feasibility and the principal clinical outcome for efficacy and safety was 24-hour mortality. RESULTS: Mortality at 24 hours was 5.9% in patients who were randomized to early cold stored platelet transfusion compared with 10.2% in the standard care arm (difference, -4.3%; 95% CI, -12.8% to 3.5%; P =0.26). No significant differences were found for any of the prespecified ancillary outcomes. Rates of arterial and/or venous thromboembolism and adverse events did not differ across treatment groups. CONCLUSIONS AND RELEVANCE: In severely injured patients, early cold stored platelet transfusion is feasible, safe and did not result in a significant lower rate of 24-hour mortality. Early cold stored platelet transfusion did not result in a higher incidence of arterial and/or venous thrombotic complications or adverse events. The storage age of the cold stored platelet product was not associated with significant outcome differences. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT04667468.

The Efficacy of Low-Titer Group O Whole Blood Compared With Component Therapy in Civilian Trauma Patients: A Meta-Analysis.

OBJECTIVES: To assess if transfusion with low-titer group O whole blood (LTOWB) is associated with improved early and/or late survival compared with component blood product therapy (CT) in bleeding trauma patients. DATA SOURCES: A systematic search of PubMed, CINAHL, and Web of Science was performed from their inception through December 1, 2023. Key terms included injury, hemorrhage, bleeding, blood transfusion, and whole blood. STUDY SELECTION: All studies comparing outcomes in injured civilian adults and children who received LTOWB versus CT were included. DATA EXTRACTION: Data including author, publication year, sample size, total blood volumes, and clinical outcomes were extracted from each article and reported following the Meta-analysis Of Observational Studies in Epidemiology guidelines. Main outcomes were 24-hour (early) and combined 28-day, 30-day, and in-hospital (late) mortality rates between recipients of LTOWB versus CT, which were pooled using random-effects models. DATA SYNTHESIS: Of 1297 studies reviewed, 24 were appropriate for analysis. Total subjects numbered 58,717 of whom 5,164 received LTOWB. Eleven studies included adults-only, seven included both adults and adolescents, and six only included children. The median (interquartile range) age for patients who received LTOWB and CT was 35 years (24-39) and 35.5 years (23-39), respectively. Overall, 14 studies reported early mortality and 22 studies reported late mortality. LTOWB was associated with improved 24-hour survival (risk ratios [RRs] [95% CI] = 1.07 [1.03-1.12]) and late (RR [95% CI] = 1.05 [1.01-1.09]) survival compared with component therapy. There was no evidence of small study bias and all studies were graded as a moderate level of bias. CONCLUSIONS: These data suggest hemostatic resuscitation with LTOWB compared with CT improves early and late survival outcomes in bleeding civilian trauma patients. The majority of subjects were injured adults; multicenter randomized controlled studies in injured adults and children are underway to confirm these findings.

Survey of policies at US hospitals on the selection of RhD type of low-titer O whole blood for use in trauma resuscitation.

BACKGROUND: Low-titer group O whole blood (LTOWB) use is increasing due to data suggesting improved outcomes and safety. One barrier to use is low availability of RhD-negative LTOWB. This survey examined US hospital policies regarding the selection of RhD type of blood products in bleeding emergencies. STUDY DESIGN AND METHODS: A web-based survey of blood bank directors was conducted to determine their hospital's RhD-type selection policies for blood issued for massive bleeding. RESULTS: There was a 61% response rate (101/157) and of those responses, 95 were complete. Respondents indicated that 40% (38/95) use only red blood cells (RBCs) and 60% (57/95) use LTOWB. For hospitals that issue LTOWB (N = 57), 67% are supplied only with RhD-positive, 2% only with RhD-negative, and 32% with both RhD-positive and RhD-negative LTOWB. At sites using LTOWB, RhD-negative LTOWB is used exclusively or preferentially more commonly in adult females of childbearing potential (FCP) (46%) and pediatric FCP (55%) than in men (4%) and boys (24%). RhD-positive LTOWB is used exclusively or preferentially more commonly in men (94%) and boys (54%) than in adult FCP (40%) or pediatric FCP (21%). At sites using LTOWB, it is not permitted for adult FCPs at 12%, pediatric FCP at 21.4%, and boys at 17.1%. CONCLUSION: Hospitals prefer issuing RhD-negative LTOWB for females although they are often ineligible to receive RhD-negative LTOWB due to supply constraints. The risk and benefits of LTOWB compared to the rare occurrence of hemolytic disease of the fetus/newborn (HDFN) need further examination in the context of withholding a therapy for females that has the potential for improved outcomes.

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.

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.

Increased platelet to red blood cell transfusion ratio associated with acute kidney injury in children with life-threatening bleeding.

INTRODUCTION: Transfusion may increase the risk of organ failure through immunomodulatory effects. The primary objective of this study was to assess for patient or transfusion-related factors that are independently associated with the risk of acute kidney injury (AKI) and acute respiratory distress syndrome (ARDS) in a cohort of children with life-threatening bleeding from all etiologies. METHODS: In a secondary analysis of the prospective observational massive transfusion in children (MATIC) study, multivariable logistic regression was performed in an adjusted analysis to determine if blood product ratios or deficits were independently associated with AKI or ARDS in children with life-threatening bleeding. RESULTS: There were 449 children included with a median (interquartile range, IQR) age of 7.3 years (1.7-14.7). Within 5 days of the life-threatening bleeding event, AKI occurred in 18.5% and ARDS occurred in 20.3% of the subjects. Every 10% increase in the platelet to red blood cell transfusion ratio is independently associated with a 12.7% increase in the odds of AKI (adjusted odds ratio 1.127; 95% confidence interval 1.025-1.239; p-value .013). Subjects with operative or medical etiologies were independently associated with an increased risk of AKI compared to those with traumatic injury. No transfusion-related variables were independently associated with the risk of developing ARDS. CONCLUSION: The use of increased platelet to red blood cell transfusion ratios in children with life-threatening bleeding of any etiology may increase the risk of AKI but not ARDS. Prospective trials are needed to determine if increased platelet use in this cohort increases the risk of AKI to examine possible mechanisms.

Patient sex and outcomes in children with life-threatening hemorrhage.

BACKGROUND: Recent data suggest female sex imparts a survival benefit after trauma in adults. The independent associations between patient sex and age with outcomes have not been examined in children with life-threatening hemorrhage (LTH) from all etiologies. STUDY DESIGN AND METHODS: In a secondary analysis of a multicenter prospective observational study of children with LTH, Massive Transfusion in Children (MATIC), we analyzed if patient sex and age were associated with differences in severity of illness, therapies, and outcomes. Primary outcomes were 24 hour mortality and weight-adjusted transfusion volume during LTH. Kruskal-Wallis, chi-square testing, and multivariable linear regression were used for adjusted analyses. RESULTS: Of 449 children, 45% were females and 55% were males. Females were more commonly younger, white, and with less trauma as the etiology of LTH compared to males. Markers of clinical severity were similar between groups, except injury severity score (ISS) was higher in females in the trauma subgroup. In terms of resuscitative practices, females received greater weight-adjusted total transfusion volumes compared to males (76 (40-150) mL/kg vs. 53 (24-100) mL/kg), as well as increased red blood cells (RBCs), plasma, and platelets compared to males. After adjustment for confounders, female sex and age 0-11 years were independently associated with increased transfusion volume during LTH. There were no differences in mortality or adverse outcomes according to patient sex. CONCLUSION: Patient sex and age may impact factors associated with LTH and therapies received. Studies in developmental hemostasis are needed to determine the optimal transfusion strategy for LTH according to patient sex and age.

Low Titer Group O Whole Blood In Injured Children Requiring Massive Transfusion.

OBJECTIVE: The aim of this study was to assess the survival impact of low-titer group O whole blood (LTOWB) in injured pediatric patients who require massive transfusion. SUMMARY BACKGROUND DATA: Limited data are available regarding the effectiveness of LTOWB in pediatric trauma. METHODS: A prospective observational study of children requiring massive transfusion after injury at UPMC Children's Hospital of Pittsburgh, an urban academic pediatric Level 1 trauma center. Injured children ages 1 to 17 years who received a total of >40 mL/kg of LTOWB and/or conventional components over the 24 hours after admission were included. Patient characteristics, blood product utilization and clinical outcomes were analyzed using Kaplan-Meier survival curves, log rank tests and Cox proportional hazards regression analyses. The primary outcome was 28-day survival. RESULTS: Of patients analyzed, 27 of 80 (33%) received LTOWB as part of their hemostatic resuscitation. The LTOWB group was comparable to the component therapy group on baseline demographic and physiologic parameters except older age, higher body weight, and lower red blood cell and plasma transfusion volumes. After adjusting for age, total blood product volume transfused in 24 hours, admission base deficit, international normalized ratio (INR), and injury severity score (ISS), children who received LTOWB as part of their resuscitation had significantly improved survival at both 72 hours and 28 days post-trauma [adjusted odds ratio (AOR) 0.23, P = 0.009 and AOR 0.41, P = 0.02, respectively]; 6-hour survival was not statistically significant (AOR = 0.51, P = 0.30). Survivors at 28 days in the LTOWB group had reduced hospital LOS, ICU LOS, and ventilator days compared to the CT group. CONCLUSION: Administration of LTOWB during the hemostatic resuscitation of injured children requiring massive transfusion was independently associated with improved 72-hour and 28-day survival.

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.

Cryoprecipitate for the treatment of life-threatening hemorrhage in children.

BACKGROUND: Hypofibrinogenemia is an important risk factor for poor outcomes in children with severe bleeding. There is a paucity of data on the impact of cryoprecipitate transfusion on outcomes in pediatric patients with life-threatening hemorrhage (LTH). STUDY DESIGN AND METHODS: This secondary analysis of a multicenter prospective observational study of children with LTH investigated subjects who were categorized by receipt of cryoprecipitate during their resuscitation and according to the etiology of their bleeding: trauma, operative, and medical. Bivariate analysis was performed to identify variables associated with 6-h, 24-h, and 28-day mortality. Cox Hazard regression models were generated to adjust for potential confounders. RESULTS: Cryoprecipitate was transfused to 33.9% (152/449) of children during LTH. The median (Interquartile range) time to cryoprecipitate administration was 108 (47-212) minutes. Children in the cryoprecipitate group were younger, more often female, with higher BMI and pre-LTH PRISM score and lower platelet counts. After adjusting for PRISM score, bleeding etiology, age, sex, RBC volume, platelet volume, antifibrinolytic use and cardiac arrest, cryoprecipitate administration was independently associated with lower 6-h mortality, Hazard Ratio (95% CI), 0.41 (0.19-0.89), (p = 0.02) and 24-h mortality, Hazard Ratio (95% CI), 0.46 (0.24-0.89), (p = 0.02). CONCLUSION: Cryoprecipitate transfusion to children with LTH was associated with reduced early mortality. A prospective randomized trial is needed to determine if cryoprecipitate can improve outcomes in children with LTH.

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.

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.

Epsilon aminocaproic acid is associated with acute kidney injury after life-threatening hemorrhage in children.

BACKGROUND: Antifibrinolytic medications have been associated with reduced mortality in pediatric hemorrhage but may contribute to adverse events such as acute kidney injury (AKI). STUDY DESIGN AND METHODS: We conducted a secondary analysis of the MAssive Transfusion in Children (MATIC), a prospectively collected database of children with life-threatening hemorrhage (LTH), and evaluated for risk of adverse events with either antifibrinolytic treatment, epsilon aminocaproic acid (EACA) or tranexamic acid (TXA). The primary outcome was AKI and secondary outcomes were acute respiratory distress syndrome (ARDS) and sepsis. RESULTS: Of 448 children included, median (interquartile range) age was 7 (2-15) years, 55% were male, and LTH etiology was 46% trauma, 34% operative, and 20% medical. Three hundred and ninety-three patients did not receive an antifibrinolytic (88%); 37 (8%) received TXA and 18 (4%) received EACA. Sixty-seven (17.1%) patients in the no antifibrinolytic group developed AKI, 6 (16.2%) patients in the TXA group, and 9 (50%) patients in the EACA group (p = .002). After adjusting for cardiothoracic surgery, cyanotic heart disease, preexisting renal disease, lowest hemoglobin pre-LTH, and total weight-adjusted transfusion volume during the LTH, the EACA group had increased risk of AKI (adjusted odds ratio 3.3 [95% CI: 1.0-10.3]) compared to no antifibrinolytic. TXA was not associated with AKI. Neither antifibrinolytic treatment was associated with ARDS or sepsis. CONCLUSION: Administration of EACA during LTH may increase the risk of AKI. Additional studies are needed to compare the risk of AKI between EACA and TXA in pediatric patients.

Parent perceptions of emergent blood transfusion in children.

BACKGROUND: RhD-negative blood products are in chronic short supply leading to renewed interest in utilizing RhD-positive blood products for emergency transfusions. This study assessed parental perceptions of emergency RhD-positive blood use in children. METHODS: A survey of parents/guardians was conducted on their tolerance of transfusing RhD-positive blood to RhD-negative female children ≤17 years old at four level 1 pediatric hospitals. RESULTS: In total, 621 parents/guardians were approached of whom 378/621 (61%) completed the survey in its entirety and were included in the analysis. Respondents were mostly females [295/378 (78%)], White [242/378 (64%)], had some college education [217/378 (57%)] and less than $60,000 annual income [193/378 (51%)]. Respondents had a total of 547 female children. Most children's ABO [320/547 (59%)] and RhD type [348/547 (64%)] were not known by their parents; of children with known RhD type, 58/186 (31%) were RhD-negative. When the risk of harm to a future fetus was given as 0-6%, more than 80% of respondents indicated that they were likely to accept RhD-positive blood transfusions on behalf of RhD-negative female children in a life-threatening situation. The rate of willingness to accept emergent RhD-incompatible blood transfusions significantly increased as the potential survival benefit of the transfusion increased. CONCLUSION: Most parents were willing to accept RhD-positive blood products on behalf of RhD-negative female children in an emergency situation. Further discussions and evidence-based guidelines on transfusing RhD-positive blood products to RhD-unknown females in emergency settings are needed.

Blood component ratios in children with non-traumatic life-threatening bleeding.

BACKGROUND AND OBJECTIVES: In paediatric trauma patients, there are limited prospective data regarding blood components and mortality, with some literature suggesting decreased mortality with high ratios of plasma and platelets to red blood cells (RBCs) in massive transfusions; however, most paediatric massive transfusions occur for non-traumatic aetiologies and few studies assess blood product ratios in these children. This study's objective was to evaluate whether high blood product ratios or low deficits conferred a survival benefit in children with non-traumatic life-threatening bleeding. MATERIALS AND METHODS: This is a secondary analysis of the five-year, multicentre, prospective, observational massive transfusion epidemiology and outcomes in children study of children with life-threatening bleeding from US, Canadian and Italian medical centres. Primary interventions were plasma:RBC and platelets:RBC (high ratio ≥1:2 ml/kg) and plasma and platelet deficits. The primary outcome was mortality at 6 h, 24 h and 28 days. Multivariate logistic regression models were used to determine independent associations with mortality. RESULTS: A total of 222 children were included from 24 medical centres: 145 children (median [interquartile range] age 2.1 years [0.3-11.8]) with operative bleeding and 77 (8.0 years [1.2-14.7]) with medical bleeding. In adjusted analyses, neither blood product ratios nor deficits were associated with mortality at 6 h, 24 h or 28 days. CONCLUSION: This paper addresses a lack of prospective data in children regarding optimal empiric massive transfusion strategies in non-traumatic massive haemorrhage and in finding no decrease in mortality with high plasma or platelet to RBC ratios or lower deficits supports an exploratory analysis for mortality.

Association of Thromboelastography with Progression of Hemorrhagic Injury in Children with Traumatic Brain Injury.

INTRODUCTION: Progression of hemorrhagic injury (PHI) in children with traumatic brain injury portends poor outcomes. The association between thromboelastography (TEG), functional coagulation assays, and PHI is not well characterized in children. METHODS: This was a retrospective cohort study of children presenting with PHI at a pediatric level I academic trauma center from 2015 to 2020. Inclusion criteria were as follows: age less than 18 years, intracranial hemorrhage on admission head computed tomography scan, and admission rapid TEG assay and conventional coagulation tests. PHI was defined by the following radiographic criteria: any expansion of or new intracranial hemorrhage on subsequent head computed tomography scan. Rapid TEG values included Activated Clotting Time (ACT), alpha angle, maximum amplitude, and lysis at 30 min. Wilcoxon rank-sum test was used to assess baseline differences between groups with PHI and without PHI, including laboratory assays. Univariate analysis was performed to examine the association between variables of interest and PHI. Patients were dichotomized on the basis of this cut point to generate a "low ACT" group and a "high ACT" group. These variables were included in a multivariable logistic regression model to determine independent association with traumatic brain injury progression. RESULTS: In total, 219 patients met criteria for analysis. In this cohort, the median (interquartile range [IQR]) age = 6 (2-12) years, median (IQR) Injury Severity Score = 21 (11-27), 68% were boys, and 69% sustained blunt injury. The rate of PHI was 25% (54). Median (IQR) time to PHI was 1 (0-4) days. Children with PHI had a higher Injury Severity Score (p < 0.001), lower Glasgow Coma Scale (p < 0.001), greater incidence of shock (p = 0.04), and lower admission hemoglobin (p = 0.02) compared with those without PHI. Children with PHI had a higher International Normalized Ratio (INR) and longer TEG-ACT; other TEG values (alpha angle, maximum amplitude, and lysis at 30 min) were not associated with PHI. In the logistic regression model accounting for other covariates associated with PHI, elevated ACT remained an independent predictor of progression (odds ratio = 2.25, 95% confidence interval 1.09-4.66; p = 0.03; area under the receiver operating characteristic curve = 0.76). After adjusting for confounders, INR fell out of the model and was not an independent predictor of progression (odds ratio = 1.32, 95% confidence interval 0.60-2.93; p = 0.49). CONCLUSIONS: Although INR was elevated in children with PHI and has been associated with poor clinical outcomes, only admission TEG-ACT was independently associated with PHI. Further study is warranted to determine whether TEG-ACT reflects an actionable therapeutic target.

Use of Antifibrinolytics in Pediatric Life-Threatening Hemorrhage: A Prospective Observational Multicenter Study.

OBJECTIVES: To assess the impact of antifibrinolytics in children with life-threatening hemorrhage. DESIGN: Secondary analysis of the MAssive Transfusion epidemiology and outcomes In Children study dataset, a prospective observational study of children with life-threatening bleeding events. SETTING: Twenty-four children's hospitals in the United States, Canada, and Italy. PATIENTS: Children 0-17 years old who received greater than 40 mL/kg of total blood products over 6 hours or were transfused under activation of massive transfusion protocol. INTERVENTION/EXPOSURE: Children were compared according to receipt of antifibrinolytic medication (tranexamic acid or aminocaproic acid) during the bleeding event. MEASUREMENTS AND MAIN RESULTS: Patient characteristics, medications administered, and clinical outcomes were analyzed using Cox proportional hazard and Kaplan-Meier survival analysis. The primary outcome was 24-hour mortality. Of 449 patients analyzed, median age was 7 years (2-15 yr), and 55% were male. The etiology of bleeding was 46% traumatic, 34% operative, and 20% medical. Twelve percent received antifibrinolytic medication during the bleeding event (n = 54 unique subjects; n = 18 epsilon aminocaproic acid, n = 35 tranexamic acid, and n = 1 both). The antifibrinolytic group was comparable with the nonantifibrinolytic group on baseline demographic and physiologic parameters; the antifibrinolytic group had longer massive transfusion protocol duration, received greater volume blood products, and received factor VII more frequently. In the antifibrinolytic group, there was significantly less 6-hour mortality overall (6% vs 17%; p = 0.04) and less 6-hour mortality due to hemorrhage (4% vs 14%; p = 0.04). After adjusting for age, bleeding etiology, Pediatric Risk of Mortality score, and plasma deficit, the antifibrinolytic group had decreased mortality at 6- and 24-hour postbleed (adjusted odds ratio, 0.29 [95% CI, 0.09-0.93]; p = 0.04 and adjusted odds ratio, 0.45 [95% CI, 0.21-0.98]; p = 0.04, respectively). CONCLUSIONS: Administration of antifibrinolytic medications during the life-threatening event was independently associated with improved 6- and 24-hour survivals in bleeding children. Consideration should be given to use of antifibrinolytics in pediatric patients with life-threatening hemorrhage.

Characterization of immediate and early mortality after repair of ruptured abdominal aortic aneurysm.

BACKGROUND: We sought to compare immediate and early mortality among patients undergoing ruptured abdominal aortic aneurysm (RAAA) repair. Evaluation of RAAA has focused on 30-day postoperative mortality. Other emergency conditions such as trauma have demonstrated a multimodal mortality distribution within the 30-day window, expanding the pathophysiologic understanding and allowing for intervention investigations with practice changing and lifesaving results. However, the temporal distribution and risk factors of postoperative morbidity and mortality in RAAA have yet to be investigated. METHODS: We evaluated factors associated with RAAA postoperative mortality in immediate (<1 day) and early (1-30 days) postoperative periods in a landmarked retrospective cohort study using data from the Vascular Quality Initiative (2010-2020). RESULTS: We identified 5157 RAAA repairs (mean age, 72 ± 10 years; 77% male; 88% White; 61% endovascular). The mortality rate in the immediate period was 10.2% (528/5157) and the early mortality rate was 22.1% (918/4163). In multivariable regression analyses, signs of hemorrhagic shock (ie, hemoglobin <7 g/dL: adjusted odds ratio [aOR], 1.87 [95% confidence interval [CI], 1.14-3.06]; any preoperative systolic blood pressure <70 mm Hg: aOR, 1.40 [95% CI, 1.04-1.89]; and estimated blood loss >40%: aOR, 3.65 [95% CI, 2.29-5.83]) were associated with an increased risk of immediate mortality. Comorbid conditions (heart failure: aOR, 1.38 [95% CI, 1.00-1.92]; pulmonary disease: aOR, 1.29 [95% CI, 1.05-1.58]; elevated creatinine: aOR 1.26 [95% CI, 1.31-1.41]) were associated with increased risk of early mortality. CONCLUSIONS: Immediate deaths were associated predominantly with shock from massive hemorrhage, whereas early deaths were associated with comorbid conditions predisposing patients to multisystem organ failure despite successful repair. These temporal distinctions should guide future mechanistic and intervention evaluations to improve RAAA mortality.

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.