Hammel, Scott A.

Purpose: molecular testing is often indicated for recently transfused patients. However, there are no guidelines regarding the potential interference from donor DNA or whether it is necessary to wait for a period of time post-transfusion prior to genetic testing. While the majority of patients are transfused in the non-trauma setting using leukoreduced (LR) red blood cell products, the degree of leukoreduction varies among centers and is not universally practiced. Methods: whole blood units collected from anonymous donors were used in an in vitro transfusion model. One unit was split: half being leukoreduced simulating a leukopenic recipient and half left untreated. Donors were simulated by leukoreduced, partially leukoreduced (PLR), or non-leukoreduced units, transfused in 2, 5, or 16 unit equivalents. DNA from the combinations were subjected to short tandem repeat (STR) analysis for chimerism detection. Results: donor DNA was not detectable in any of the LR combinations, but detected in the PLR combinations, ranging from 0.1 to 1.5% donor DNA in the immunocompetent recipient and 6.3–27.8% in the leukopenic recipient. Non-LR donor DNA was also detected (13–95%). Conclusion: donor-derived DNA from leukoreduced blood products is unlikely to interfere with the interpretation of germline genetic testing in immunocompetent recipients but may interfere in immunocompromised recipients.

AbstractBackgroundThe COVID‐19 pandemic has placed great strain on blood resources. In an effort to extend platelet (PLT) shelf life and minimize waste, our institution transitioned room temperature to cold‐stored PLTs for administration to bleeding patients.Study Design and MethodsWe describe the administrative and technical processes involved in transitioning room temperature PLTs to cold storage in April 2020. Additionally, we describe the clinical utilization of cold‐stored PLTs in the first month of this practice change, with a focus on changes in PLT counts after transfusion, hemostasis, and safety outcomes.ResultsA total of 61 cold‐stored PLT units were transfused to 40 bleeding patients, with a median (interquartile range [IQR]) of 1 (1‐2) units per patient. The median age was 68 (59‐73) years; 58% male. Median pretransfusion and posttransfusion PLTs counts were 88 (67‐109) and 115 (93‐145). A total of 95% of transfusions were administered in the operating room: 57% cardiac surgery, 20% vascular surgery, 8% general surgery, and 5% solid organ transplantation. Hemostasis was deemed to be adequate in all cases after transfusion. There were no transfusion reactions. One patient (3%) experienced a fever and infection within 5 days of transfusion, which was unrelated to transfusion. Median (IQR) hospital length of stay was 8.5 (6‐17) days. Two patients (5%) died in the hospital of complications not related to transfusion.ConclusionCold‐stored PLT utilization was associated with adequate hemostasis and no overt signal for patient harm. Conversion from room temperature to cold‐stored PLTs may be one method of reducing waste in times of scarce blood inventories.

Background: Molecular genetic testing is increasingly utilized in clinical care, typically with peripheral blood as the preferred specimen. Despite the prevalence of therapeutic blood transfusions, whether donor DNA is present in a sufficient quantity to interfere with recipient genetic testing has not been systematically studied. Microchimerism secondary to transfusion of blood products with donor leukocytes has been well-documented in trauma patients receiving whole blood; however, most medical centers currently transfuse leukoreduced (LR) red blood cell products for non-trauma patients. The degree of leukoreduction varies among centers, but to meet AABB standards must be <5x106 white blood cells (WBC) in 95% of units tested. We sought to determine what quantity, if any, of infused LR or non-LR (NLR) products leads to detectable microchimerism that may impact genetic test results. Methods: We performed an in vitro spiking study utilizing four whole blood units collected from different anonymous donors. Three were leukoreduced at varying levels in order to establish a LR (per our institutional guidelines and standards), a partially leukoreduced (PLR) and a NLR unit, which were then considered "donors". The 4th unit was divided to generate two separate "recipients". The first half was left untreated simulating an immunocompetent recipient while the other was leukoreduced to mimic a leukopenic recipient. Based on a 70 kg patient, we calculated the volume of blood from each "donor" to mix with aliquots of each "recipient" to represent a transfusion of 2, 5, or 16 units, with 2 units corresponding to a double apheresis red blood cell (RBC) transfusion and 16 units corresponding to a near total volume transfusion. DNA was extracted from each individual unit as well as all "transfused" combinations within 24 hours of mixing. Chimerism analysis was then performed by STR analysis using the GlobalFiler PCR amplification kit followed by ChimerMarker analysis software. Results: None of the LR units, despite volume transfused, revealed any level of microchimerism in either the immunocompetent or leukopenic "recipients". The PLR transfused combinations displayed levels ranging from 0.14% to 1.52% of donor chimerism for the immunocompetent "recipient", which is below the limit of detection for most clinical assays evaluating germline genetic variation, and 6.3% to 27.78% of donor chimerism for the leukopenic "recipient", which would be expected to impact a subset of clinical genetic assays. The NLR transfused combinations displayed levels ranging from 13.28% to 95.66% of donor chimerism. Discussion:In vitro "transfusion" of LR RBCs into simulated immunocompetent or leukopenic samples does not lead to detectable donor DNA. However, "transfusion" of PLR and NLR units in an in vitro model reveals significant levels of microchimerism dependent on volume transfused and immune status of the "recipient" which implies possible risk for impact on clinical genetic tests. The minimum time required for clearance of donor leukocytes in the recipient is unknown; we were unable to fully evaluate this and other variables in our in vitro system, but follow-up in vivo studies addressing this question are planned. Disclosures No relevant conflicts of interest to declare.

BACKGROUNDLaboratory and clinical evidence suggest that cold‐stored platelets (CS‐PLTs) might be preferable to room temperature platelets (RT‐PLTs) for active bleeding. Ease of prehospital use plus potential hemostatic superiority led our facility to pursue approval of CS‐PLTs for actively bleeding trauma patients.STUDY DESIGN AND METHODSFrom November 18, 2013, through October 8, 2015, correspondence was exchanged between our facility, the AABB, and the US Food and Drug Administration (FDA). An initial AABB variance request was for 5‐day CS‐PLTs without agitation. The AABB deferred its decision pending FDA approval to use our platelet (PLT) bags for CS‐PLTs. On March 27, 2015, the FDA approved 3‐day CS‐PLTs without agitation. On October 8, 2015, the AABB approved 3‐day CS‐PLTs without agitation and without bacterial testing for actively bleeding trauma patients. Our facility's goal is to carry CS‐PLTs on air ambulances.RESULTSCS‐PLTs have been used for trauma patients at our facility since October 2015. As of August 2016, a total of 21 (19.1%) of 119 CS‐PLTs have been transfused. The short 3‐day storage period combined with the formation of clots in plasma‐rich CS‐PLTs during storage have been the major causes of a high (80.9%) discard rate.CONCLUSIONIn the future, pathogen‐reduced (PR), PLT additive solution (PAS) CS‐PLTs seem more practical due to low risks of bacterial contamination and storage‐related clotting. This should make longer storage of CS‐PLTs feasible (e.g., 10 days or more). With a longer shelf life, PR PAS CS‐PLTs could potentially be used in a wider range of patient populations.

Almost 50% of trauma‐related fatalities within the first 24 hours of injury are related to hemorrhage. Improved survival in severely injured patients has been demonstrated when massive transfusion protocols are rapidly invoked as part of a therapeutic approach known as damage control resuscitation (DCR). DCR incorporates the early use of plasma to prevent or correct trauma‐induced coagulopathy. DCR often requires the transfusion of plasma before determination of the recipient's ABO group. Historically, group AB plasma has been considered the “universal donor” plasma product. At our facility, the number of AB plasma products produced on an annual basis was found to be inadequate to support the trauma service's DCR program. A joint decision was made by the transfusion medicine and trauma services to provide group A thawed plasma (TP) for in‐hospital and prehospital DCR protocols. A description of the implementation of group A TP into the DCR program is provided as well as outcome data pertaining to the use of TP in trauma patients.