The safety of ABO minor incompatible platelets transfusions using a rapid infuser.

BACKGROUND: Administering platelets through a rapid infuser is proven to be safe. However, the clinical significance of infusing ABO-incompatible platelets with red blood cells (RBCs) in a rapid infuser remains unclear. There is a theoretical risk that isoagglutinin in the plasma of a platelet unit can interact with RBCs and induce hemolysis. MATERIALS AND METHODS: Seven in vitro studies were performed including five cases (type A RBCs and type O platelets) and two controls (type A RBCs and platelets). Anti-A titers were measured in platelet units. An RBC unit and a platelet unit were mixed in the rapid infuser reservoir and incubated for 30 min. The primary outcome was the presence of hemolysis based on the following parameters: free hemoglobin concentration, hemolysis check, direct antiglobulin test (DAT), and direct agglutination. RESULTS: The post-mix DAT was positive for IgG in all test samples (5/5), and weakly positive for complement in 3/5. The changes in free Hb in test cases between measured and calculated post-mix spanned -2.2 to +3.4 mg/dL. Post-mix hemolysis check was negative in 3/5 and slightly positive in 2/5 cases, with no significant differences compared to the control case. Anti-A titers ranged from 16 to 512 and were not associated with hemolysis. All samples were negative for direct agglutination. CONCLUSION: Our study suggested that mixing ABO-incompatible platelets with RBCs in a rapid infuser does not induce in vitro hemolysis. These findings support the use of rapid infusers regardless of platelet compatibility in support of hemostatic resuscitation.

How we approach transfusions in a patient with high risk of alloimmunization from McLeod phenotype.

McLeod phenotype-caused by the missing Xk protein-is a very rare red cell phenotype, one characteristic of McLeod syndrome, and sometimes associated with X-linked chronic granulomatous disease (CGD). Diagnosis of McLeod phenotype is important for appropriate transfusion management, because red blood cells from all healthy donors will have the Xk protein with its Kx antigen and can lead to red cell antibody formation without the ability to find compatible McLeod phenotype blood for transfusion. We offer a review and approach to diagnosis of the McLeod phenotype and special transfusion considerations.

Monitoring Direct Thrombin Inhibitors With Calibrated Diluted Thrombin Time vs Activated Partial Thromboplastin Time in Pediatric Patients.

OBJECTIVES: Activated partial thromboplastin time (aPTT) is the primary test used to monitor intravenous (IV) direct thrombin inhibitors (DTIs) but has many limitations. The plasma diluted thrombin time (dTT) has shown better correlation with DTI levels than aPTT. This study compared dose-response curves for dTT and aPTT in pediatric patients receiving argatroban and bivalirudin. METHODS: A retrospective review of pediatric patients treated with argatroban (n = 45) or bivalirudin (n = 14) monitored with dTT and aPTT. RESULTS: The dTT assay was calibrated to report DTI concentrations in µg/mL for argatroban and bivalirudin with good analytic sensitivity and specificity. The dTT was fivefold more likely to show a stable dose-response slope than the aPTT (P < .0002; odds ratio, 4.9). For patients in whom both dTT and aPTT showed a significant correlation between dose and assay results, dTT had a higher average correlation factor compared with aPTT (P = .007). Argatroban dose-response slopes showed more inter- and intrapatient variation than bivalirudin (dose-response slope coefficient of variation, 132% vs 52%). CONCLUSIONS: The dTT assay was more likely to show a stable dose response and have a stronger correlation with DTI dose than aPTT. Argatroban shows more variation in dose response than bivalirudin.

Drivers of blood use in paediatric trauma: A retrospective cohort study.

OBJECTIVES: We asked whether age or injury severity drives blood use patterns in paediatric trauma. BACKGROUND: Transfusion for paediatric trauma care is complicated by known developmental differences in coagulation and injury patterns. METHODS/MATERIALS: We linked 10 years of Trauma Registry and blood bank data, 2011-2020, for all acute trauma patients aged <18 treated at a large US Level 1 adult and paediatric trauma centre. We assessed age, injury severity and mechanism for association with any blood use, use within the first 4 h of care, and resuscitation balance, using grouped-age Chi-square and multivariable regression models. RESULTS: Of 60 066 acute trauma arrivals at our centre in the study period, 7979 (13.3%) met inclusion criteria. Median age (IQR) was (7.6[2.4-14.5]); 6230(78.1%) were < 15 years old; 590(7.4%) received any blood products; and 128(1.6%) died. Among the 5842(73.2%) patients with impact-related injury, 2023(34.6%) met standards for severe injury (New Injury Severity Score [NISS] ≥ 16); 541(9.3%) were transfused, 171(31.6%) in the first 4 h and 72(13.3%) using ≥3 units of products in the first hour. Firearms injuries were the most severe, most likely to be transfused urgently, using balanced resuscitation, and to die (p < 0.001 for all). Multivariable logistic regression showed any blood use as strongly associated with NISS (Odds Ratio 1.124832; p < 0.0001; 95% CI 1.11-1.13) but not with age (OR 0.98; p = 0.07; 95% CI 0.96-1.00). CONCLUSION: Transfusion in the care of acute paediatric trauma is uncommon (<10% of injured minors in our cohorts received any blood products), and injury severity, particularly firearms injury-not age-drove transfusion.

The transfusion service laboratory in virtual reality.

Due to the global SARS-CoV-2 pandemic, in-person laboratory medicine clerkships were converted to distance learning. The remote clerkship format provided advantages of allowing participation of students from more locations and greater scheduling flexibility but provided new challenges of maintaining learner engagement and providing experiential content of the laboratory environment. Gamification of educational content is one educational modality that has shown effectiveness in a multitude of different contexts to increase learner engagement and retention. Therefore, we created an interactive, educational 360° virtual reality walkthrough tour using off-the-shelf commercially available 360° cameras and software of the Transfusion service and Microbiology Laboratories. The process consists of taking multiple 360° still-images within the space, color-correction, blurring the faces of staff or sensitive information, adding navigation buttons, and other interactive elements. The virtual tours were used for both recruitment and education with further plans to integrate the learning modality into the curriculum. The clerkship is likely to remain as partially or fully as remote learning so such walkthrough tours will continue to remain relevant. This technology can be applied globally to other departments and institutions for education or recruitment.

Cold-stored whole blood and platelet counts in severe acute injury: A comparison of four retrospective cohorts.

BACKGROUND: Low-titer group O whole blood (LTOWB) is attractive for acute trauma care as it delivers concentrated and balanced hemostatic resuscitation in single large bags. Whether cold-stored LTOWB can sustain platelet counts is unclear. STUDY DESIGN AND METHODS: Four cohorts of trauma patients-three historic, one retrospective-were identified by their urgency of blood use. Admission and all subsequent platelet counts over the first 24 h of care were compared with t-tests. The cohorts were as follows: 1292 patients at Maryland Shock Trauma as described by Stansbury and colleagues in 2013; 35 patients enrolled locally in the 1:1:2 arm of the pragmatic randomized optimal plasma and platelet ratios (PROPPR) trial; 34 patients enrolled locally in the 1:1:1 arm of PROPPR; and 59 patients receiving more than 3 units of LTOWB enroute to or at our Level 1 trauma center, 2019-2020. RESULTS: Mean age of LTOWB units transfused was 9 ± 5 days and mean dose was 5 ± 2 units. All four cohorts were profoundly injured (mean Injury Severity Score ≥ 31), with mean first platelet counts 204-228 K/µ and subsequent counts approximately 100 k/µl lower. Through the first 24 h of care, mean platelet counts decreased least, 79 and 83 103 /µl, in the 1:1:1 PROPPR and LTOWB cohorts. Mean platelet counts in patients transfused with LTOWB remained stable after the third hour of care. DISCUSSION: LTOWB transfusion was associated with lesser mean decrease in platelet counts during the first 24 h after injury, similar to those observed among patients receiving components 1:1:1 component in the PROPPR study.