Vesiculation in irradiated and cation-leaky-stored red blood cells.

BACKGROUND: Extracellular vesicles (EVs) are released by red blood cells (RBCs) throughout their life-span and also during hypothermic storage when they accumulate in the blood bag. We queried whether stored RBCs with increased cation permeability, either from donors with familial pseudohyperkalaemia (FP) or caused by irradiation, vesiculate more readily. STUDY DESIGN AND METHODS: Recent technical advances have revealed at least two sub-populations of MVs in RBC storage units: macrovesicles (2-6 µm) and microvesicles (1-2 µm). Using nanoparticle tracking analysis, imaging flow cytometry, and protein quantification methods, we measured and characterized vesicles released by RBCs from control and FP individuals at three different storage time-points (day 4, day 17, and day 29). The RBCs had either been stored untreated or irradiated on either day 1 or day 14 of storage. RESULTS: We found no difference in the number or size of vesicles released between cation-leaky FP RBCs and non-FP controls. Similarly, irradiated and non-irradiated RBCs showed very similar patterns of vesicle release to during cold-storage. The only significant difference in vesicle release was the increase in accumulated vesicles with length of storage time which has been reported previously. DISCUSSION: EVs in stored blood are potential contributors to adverse transfusion reactions. The number of vesicles released during 35-day hypothermic storage varies between donors and increases with storage duration. However, increased cation permeability and irradiation do not appear to affect vesicle formation during RBC cold-storage.

Influence of donor age, sex and ethnicity on high-titre anti-A and -B: Review of 6 million donations from two national blood providers.

BACKGROUND AND OBJECTIVES: Some blood operators routinely screen blood donations for high-titre (HT) anti-A/B to reduce the risk of a haemolytic transfusion reaction due to out-of-group plasma-rich components. We assessed donor factors associated with an increased likelihood of screening positive and compared routine data between England and Australia. MATERIALS AND METHODS: Data were assessed from HT screening during 2018-2020 in Australia and 2018-2021 in England, totalling nearly 6 million blood donations. Screening was performed using a Beckman Coulter PK7300 analyser with a micro-titre plate saline direct agglutination test in both countries, although different reagent red cells were chosen. HT-positive was defined as testing positive at a titre of 128 or above. RESULTS: The likelihood of a donor testing HT-positive was greater for females than males, declined with age and was dependent on the ABO group. However, the proportion of donors testing HT-positive was consistently higher in Australia than in England: overall, 14% of group O donations and 5% of group A donations in England tested HT-positive, compared with 51% and 22%, respectively in Australia. English data also showed that donors from Black, Asian or mixed ethnic backgrounds were more likely to test HT-positive than White donors. CONCLUSION: These data demonstrate that donor sex, age, ABO group and ethnicity affect the likelihood of testing HT-positive. Differences in testing methods likely had a significant impact on the proportion of donors testing as HT-positive or -negative rather than any differences in donor populations.

Assessment of the soluble proteins HMGB1, CD40L and CD62P during various platelet preparation processes and the storage of platelet concentrates: The BEST collaborative study.

BACKGROUND: Structural and biochemical changes in stored platelets are influenced by collection and processing methods. This international study investigates the effects of platelet (PLT) processing and storage conditions on HMGB1, sCD40L, and sCD62P protein levels in platelet concentrate supernatants (PCs). STUDY DESIGN/METHODS: PC supernatants (n = 3748) were collected by each international centre using identical centrifugation methods (n = 9) and tested centrally using the ELISA/Luminex platform. Apheresis versus the buffy coat (BC-PC) method, plasma storage versus PAS and RT storage versus cold (4°C) were investigated. We focused on PC preparation collecting samples during early (RT: day 1-3; cold: day 1-5) and late (RT: day 4-7; cold: day 7-10) storage time points. RESULTS: HMGB1, sCD40L, and sCD62P concentrations were similar during early storage periods, regardless of storage solution (BC-PC plasma and BC-PC PAS-E) or temperature. During storage and without PAS, sCD40L and CD62P in BC-PC supernatants increased significantly (+33% and +41%, respectively) depending on storage temperature (22 vs. 4°C). However, without PAS-E, levels decreased significantly (-31% and -20%, respectively), depending on storage temperature (22 vs. 4°C). Contrastingly, the processing method appeared to have greater impact on HMGB1 release versus storage duration. These data highlight increases in these parameters during storage and differences between preparation methods and storage temperatures. CONCLUSIONS: The HMGB1 release mechanism/intracellular pathways appear to differ from sCD62P and sCD40L. The extent to which these differences affect patient outcomes, particularly post-transfusion platelet increment and adverse events, warrants further investigation in clinical trials with various therapeutic indications.

Association of red blood cells and plasma transfusion versus red blood cell transfusion only with survival for treatment of major traumatic hemorrhage in prehospital setting in England: a multicenter study.

BACKGROUND: In-hospital acute resuscitation in trauma has evolved toward early and balanced transfusion resuscitation with red blood cells (RBC) and plasma being transfused in equal ratios. Being able to deliver this ratio in prehospital environments is a challenge. A combined component, like leukocyte-depleted red cell and plasma (RCP), could facilitate early prehospital resuscitation with RBC and plasma, while at the same time improving logistics for the team. However, there is limited evidence on the clinical benefits of RCP. OBJECTIVE: To compare prehospital transfusion of combined RCP versus RBC alone or RBC and plasma separately (RBC + P) on mortality in trauma bleeding patients. METHODS: Data were collected prospectively on patients who received prehospital transfusion (RBC + thawed plasma/Lyoplas or RCP) for traumatic hemorrhage from six prehospital services in England (2018-2020). Retrospective data on patients who transfused RBC from 2015 to 2018 were included for comparison. The association between transfusion arms and 24-h and 30-day mortality, adjusting for age, injury mechanism, age, prehospital heart rate and blood pressure, was evaluated using generalized estimating equations. RESULTS: Out of 970 recruited patients, 909 fulfilled the study criteria (RBC + P = 391, RCP = 295, RBC = 223). RBC + P patients were older (mean age 42 vs 35 years for RCP and RBC), and 80% had a blunt injury (RCP = 52%, RBC = 56%). RCP and RBC + P were associated with lower odds of death at 24-h, compared to RBC alone (adjusted odds ratio [aOR] 0.69 [95%CI: 0.52; 0.92] and 0.60 [95%CI: 0.32; 1.13], respectively). The lower odds of death for RBC + P and RCP vs RBC were driven by penetrating injury (aOR 0.22 [95%CI: 0.10; 0.53] and 0.39 [95%CI: 0.20; 0.76], respectively). There was no association between RCP or RBC + P with 30-day survival vs RBC. CONCLUSION: Prehospital plasma transfusion for penetrating injury was associated with lower odds of death at 24-h compared to RBC alone. Large trials are needed to confirm these findings.

Evaluating apheresis platelets at reduced dose as a contingency measure for extreme shortages.

BACKGROUND: The COVID19 pandemic highlights the need for contingency planning in the event of blood shortages. To increase platelet supply, we assessed the operational impact and effect on platelet quality of splitting units prior to storage. STUDY DESIGN AND METHODS: Using production figures, we modeled the impact on unit numbers, platelet counts, and volumes of splitting only apheresis double donations into three units (yielding ⅔ doses), or all standard dose units in half. To assess quality, eight pools of three ABO/Rh-matched apheresis (Trima Accel) double donations in plasma were split to ⅔ and ½ volumes in both Terumo and Fresenius storage bags. These were irradiated and subject to maximal permitted periods of nonagitation (3 × 8 h) before comparing platelet quality markers (including pH, CD62P expression) to Day 9 of storage. RESULTS: Splitting all double donations into three predicted inventory expansion of 23% overall whereas halving all standard dose units clearly doubles stock. In our study, ⅔ and ½ doses contained 153 ± 15 × 109 (~138 ml) and 113 ± 11 × 109 (~102 ml) platelets respectively. Following storage, higher pH was observed in ⅔ than in ½ doses and in Terumo compared to Fresenius bags. The higher pH was reflected in better quality markers, including lower CD62P expression. Despite the differences, on Day 8 (of pH monitoring at expiry) all ⅔ doses and most ½ doses were ≥pH 6.4. CONCLUSION: A strategy to split apheresis platelets in plasma to lower doses is feasible, maintains acceptable platelet quality, and should be considered by blood services in response to extreme shortages.

The compound effect of irradiation and familial pseudohyperkalemia on potassium leak from red blood cells.

BACKGROUND: Familial pseudohyperkalemia (FP) is a rare asymptomatic condition characterized by an increased rate of potassium leak from red blood cells (RBC) on refrigeration. Gamma irradiation compromises RBC membrane integrity and accelerates potassium leakage. Here, we compared the effect of irradiation, applied early or late in storage, on FP versus non-FP RBC. STUDY DESIGN: Five FP and 10 non-FP individuals from the National Institute for Health Research Cambridge BioResource, UK, and three FP and six non-FP individuals identified by Australian Red Cross Lifeblood consented to the study. Blood was collected according to standard practice in each center, held overnight at 18-24°C, leucocyte-depleted, and processed into red cell concentrates (RCC) in Saline Adenine Glucose Mannitol. On Day 1, RCC were split equally into six Red Cell Splits (RCS). Two RCS remained non-irradiated, two were irradiated on Day 1 and two were irradiated on Day 14. RBCs were tested over cold storage for quality parameters. RESULTS: As expected, non-irradiated FP RCS had significantly higher supernatant potassium levels than controls throughout 28 days of storage (p < .001). When irradiated early, FP RCS released potassium at similar rates to control. When irradiated late, FP RCS supernatants had higher initial post-irradiation potassium concentration than controls but were similar to controls by the end of storage (14 days post-irradiation). No other parameters studied showed a significant difference between FP and control. DISCUSSION: FP does not increase the rate of potassium leak from irradiated RBCs. Irradiation may cause a membrane defect similar to that in FP RBCs.

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.

Modelling the outcomes of different red blood cell transfusion strategies for the treatment of traumatic haemorrhage in the prehospital setting in the United Kingdom.

BACKGROUND AND OBJECTIVES: The limited supply and increasing demand of group O RhD-negative red blood cells (RBCs) have resulted in other transfusion strategies being explored by blood services that carry potential risks but may still provide an overall benefit to patients. Our aim was to analyse the potential economic benefits of prehospital transfusion (PHT) against no PHT. MATERIALS AND METHODS: The impact of three PHT strategies (RhD-negative RBC, RhD-positive RBC and no transfusion) on quality-adjusted-life-years (QALYs) of all United Kingdom trauma patients in a given year and the subset of patients considered most at risk (RhD-negative females <50 years old), was modelled. RESULTS: For the entire cohort and the subset of patients, transfusing RhD-negative RBCs generated the most QALYs (141,899 and 2977, respectively), followed by the RhD-positive RBCs (141,879.8 and 2958.8 respectively), and no prehospital RBCs (119,285 and 2503 respectively). The QALY difference between RhD-negative and RhD-positive policies was smaller (19.2, both cohorts) than RhD-positive and no RBCs policies in QALYs term (22,600 all cohort, 470 for a subset), indicating that harms from transfusing RhD-positive RBCs are lower than harms associated with no RBC transfusion. A survival increase from PHT of 0.02% (entire cohort) and 0.7% (subset cohort) would still make the RhD-positive strategy better in QALYs terms than no PHT. CONCLUSION: While the use of RhD-positive RBCs carries risks, the benefits measured in QALYs are higher than if no PHT are administered, even for women of childbearing potential. Group O RhD-positive RBCs could be considered when there is a national shortage of RhD-negative RBCs.

A comparison of the effect of X and gamma irradiation on red cell storage quality.

BACKGROUND AND OBJECTIVES: Irradiation of red cell components is indicated for recipients at risk of transfusion-associated graft vs. host disease. Current technologies available comprise of a gamma (γ) or an x source of radiation. The benefits of x vs. γ include non-radioactivity and hence no decay of the source. We aimed to compare the effect of the two technologies on red cell component storage quality post-irradiation. MATERIALS AND METHODS: Paired units of red cell concentrates (RCC), neonatal red cell splits (RCS), red cells for intra-uterine transfusion (IUT) or neonatal exchange transfusion (ExTx) were either γ- or x-irradiated. Units were sampled and tested for five storage parameters until the end of shelf life. Equivalence analysis of storage quality parameters was performed for pairs of the same components (RCC, RCS, IUT or ExTx) that were either γ- or x-irradiated. RESULTS: Nearly all component comparisons studied showed equivalence between γ and x irradiation for haemolysis, ATP, 2,3-DPG, potassium release and lactate production. The exceptions found that were deemed non-equivalent were higher haemolysis with x irradiation for ExTx, lower 2,3-DPG with x irradiation for RCS irradiated early and higher ATP with x irradiation for IUT. However, these differences were considered not clinically significant. CONCLUSION: This study has demonstrated that a range of red cell components for use in different age groups are of acceptable quality following x irradiation, with only small differences deemed clinically insignificant in a few of the measured parameters.

Challenging the 30-min rule for thawed plasma.

BACKGROUND AND OBJECTIVES: Frozen plasma (FP) is thawed prior to transfusion and stored for ≤5 days at 1-6°C. The effect of temperature excursions on the quality and safety of thawed plasma during 5-day storage was determined. MATERIALS AND METHODS: Four plasma units were pooled, split and stored at ≤-18°C for ≤90 days. Test units T30 and T60 were exposed to 20-24°C (room temperature [RT]) for 30 or 60 min, respectively, on days 0 and 2 of storage. Negative and positive control units remained refrigerated or at RT for 5 days, respectively. On Day 5, test units were exposed once to RT for 5 h. Quality assays included stability of coagulation factors FV, FVII, FVIII, fibrinogen and prothrombin time. Bacterial growth was performed in units inoculated with ~1 CFU/ml or ~100 CFU/ml of Serratia liquefaciens, Pseudomonas putida, Pseudomonas aeruginosa or Staphylococcus epidermidis on Day 0. RESULTS: Testing results of all quality parameters were comparable between T30 and T60 units (p < 0.05). Serratia liquefaciens proliferated in cold-stored plasma, while P. putida showed variable viability. Serratia epidermidis and P. aeruginosa survived but did not grow in cold-stored plasma. Positive and negative controls showed expected results. Overall, no statistical differences in bacterial concentration between T30 and T60 units were observed (p < 0.05). CONCLUSION: Multiple RT exposures for 30 or 60 min do not affect the stability of coagulation factors or promote bacterial growth in thawed plasma stored for 5 days. It is therefore safe to expose thawed plasma to uncontrolled temperatures for limited periods of 60 min.

Current challenges in platelet transfusion.

The supply of platelets for transfusion is a logistical challenge due to the physiology of platelets and current measures of transfusion performance dictating storage at 22°C and a short product shelf-life (<7 days). Demand for platelets has increased in recent years and changes in the demographics of the population may enhance this further. Many studies have been conducted to understand what the optimal dose and trigger for transfusion should be, mainly in hematology patients who are the largest cohort that receive platelets, mostly to prevent bleeding. Emerging data suggests that for bleeding patients, where immediate hemostasis is a key consideration, the current standard product may not be optimal. Alternative platelet preparation methods/storage options that may improve the hemostatic properties of platelets are under active development. In parallel with research into alternative platelet products that might enhance hemostasis, better measures for assessing bleeding risk and platelet efficacy are needed.

A comparison of platelet function in cold-stored whole blood and platelet concentrates.

BACKGROUND: There is renewed interest in the use of whole blood (WB) for the resuscitation of trauma patients. Platelet function in stored WB compared to platelet concentrates is not well established and was assessed in vitro in this study. METHODS: Leucocyte-depleted cold-stored WB (CS-WB) was prepared using a Terumo WB-SP Imuflex kit and held at 2-6°C alongside: (A) UK standard pooled platelets stored at 20-24°C (RT-PLTS), (B) pooled platelets stored at 2-6°C (CS-PLTS), and (C) platelet-rich plasma produced using the Terumo kit (CS-PRP), for 21 days. A series of in vitro assays were assessed platelet function. RESULTS: Platelet count was retained to 57 ± 14% of starting number at day 21 in CS-WB. Over time, CS-WB platelets become more activated, with increased CD62P expression (day 1: 7 ± 3.7% vs. day 21: 59 ± 17.1%) and annexin V binding (day 1: 2 ± 0.2% vs. day 21: 21 ± 15.1%). For comparison, 18.6 ± 6% of platelets in RT-PLTS demonstrated CD62P expression at day 7, whereas annexin V binding in RT-PLTS at day 7 was 2.6 ± 0.5%. Over storage, aggregatory response to agonists decreased in all arms. Functional platelet microparticles increased steadily in CS-WB throughout storage. CONCLUSION: During storage, platelet count reduced in CS-WB, whereas CD62P expression and annexin V binding increased. This was accompanied by a reduced aggregatory response, although compared to 7-day-old RT-PLTS, CS-WB maintained a maximal response to agonists for longer, suggesting that the shelf life for CS-WB can be considered for up to 21 days.

Familial pseudohyperkalemia induces significantly higher levels of extracellular potassium in early storage of red cell concentrates without affecting other standard measures of quality: A case control and allele frequency study.

BACKGROUND: Familial pseudohyperkalemia (FP) is characterized by an increased rate of potassium leakage in refrigerated red cells and is associated with the minor allele of the single nucleotide polymorphism rs148211042 (R723Q) in the ABCB6 gene. The study aims were to obtain the minor allele frequencies of ABCB6 variants and to measure supernatant potassium accumulation, and other red cell storage parameters, in red cell concentrates (RCC) from carriers of variant rs148211042 under standard blood bank conditions. STUDY DESIGN: Whole blood units were collected from 6 FP individuals and 11 controls and processed into RCC in additive solution. RCC were sampled and tested over cold storage for full blood count, extracellular potassium, glucose, lactate, microvesicle release, deformability, hemolysis, pH, adenosine triphosphate, and 2,3-diphosphoglycerate. RESULTS: Screening of genotyped cohorts identified that variant rs148211042 is present in 1 in 394 British citizens of European ancestry. FP RCC had significantly higher supernatant potassium at all time points from day 3 onwards (p < .001) and higher mean cell volume (p = .032) than controls. The initial rate of potassium release was higher in FP RCC; supernatant potassium reached 46.0 (23.8-57.6) mmol/L (mean [range]) by day 5, increasing to 68.9 (58.8-73.7) mmol/L by day 35. Other quality parameters were not significantly different between FP RCC and controls. CONCLUSION: These data suggest that if a blood donor has FP, reducing the RCC shelf-life to 5 days may be insufficient to reduce the risk of hyperkalemia in clinical scenarios such as neonatal large volume transfusion.

Residual red cells in blood components: A multisite study of fully automated enumeration using a hematology analyzer.

BACKGROUND: Manufacture of platelet concentrates (PCs) and plasma may fail to remove all residual red blood cells (rRBCs). Measuring rRBCs for compliance to guidelines has proven challenging, leading to an absence of a consensus methodology. Sysmex hematology analyzers with the Blood Bank mode (BB mode) analysis option offer the potential for automated rRBC counting. We therefore performed a two-site appraisal of the system. STUDY DESIGN AND METHODS: Performance characteristics were determined using platelet and plasma samples spiked with RBCs. Sample stability (n = 47) and the impact of sample type were also assessed. Components (platelets, n = 1474; plasma, n = 77) prepared using different routine manufacturing methods were tested to assess variation in rRBC concentration. RESULTS: Linearity studies up to 19 000 RBCs/µL demonstrated good correlation between expected and observed results (R2 ≥ 0.9731), and flow cytometric results also correlated well with BB mode (R2 = 0.9400). Precision analysis gave a limit of quantitation of 6 to 7 RBCs/µL, and carryover was 0.03%. Ethylenediaminetetraacetic acid and plain tube results were not significantly different (P ≥ 0.10), and samples were stable up to 24 hours. Apheresis PCs produced at two sites had lower rRBC concentrations (medians, 17 and 13 RBCs/µL) than those produced with the buffy coat method either manually (median, 681 RBCs/µL) or with the automated Terumo Automated Centrifuge and Separator Integration process (median, 81 RBCs/µL). All PCs failing visual inspection as having RBCs ≥4000 RBCs/µL were also detected by the BB mode. CONCLUSION: The BB mode had acceptable performance characteristics and has the potential for integration into a fully automated process control system for rRBC enumeration in plasma and PCs.

Re-introducing whole blood for transfusion: considerations for blood providers.

Whole blood is the original blood preparation but disappeared from the blood bank inventories in the 1980s following the advent of component therapy. In the early 2000s, both military and civilian practice called for changes in the transfusion support for massive haemorrhage. The 'clear fluid' policy was abandoned and replaced by early balanced transfusion of platelets, plasma and red cells. Whole blood is an attractive alternative to multi-component therapy, which offers reduced hemodilution, lower donor exposure and simplified logistics. However, the potential for wider re-introduction of whole blood requires re-evaluation of haemolysins, storage conditions and shelf-life, the need for leucocyte depletion/ pathogen reduction and inventory management for blood providers. This review addresses these questions and calls for research to define the optimal whole blood product and the indications for its use.

The use of a hematology analyzer with a new generation of software as an alternative to flow cytometry for enumerating residual white blood cells in blood components.

BACKGROUND: Leukoreduction of blood components was implemented to reduce transfusion-associated risks. The detection level for residual white blood cells (rWBCs) required to demonstrate leukoreduction was originally considered too low for hematology analyzers. Developments enabling cell counts in body fluids have, however, renewed interest in rWBC counting. An assessment of Sysmex XN hematology analyzers with software offering automated rWBC enumeration intended for use on blood components was performed. STUDY DESIGN AND METHODS: Performance characteristics were determined using platelet, red blood cell (RBC), and plasma samples spiked with WBCs. Subsequently, components (platelets, n = 1367; and plasma, n = 80) were tested and results compared with flow cytometry, to monitor leukoreduction efficiency to a level of less than 1 × 106 /unit. Components identified by flow cytometry as having poor leukoreduction, exceeding this limit, were also tested (platelets, n = 3; and RBCs, n = 10). RESULTS: Linearity studies up to 32 WBCs/µL showed good correlation between observed and expected results (R2 > 0.9996). Precision analysis gave an average limit of quantitation of 2 WBCs/µL with coefficients of variation less than 20%. Average carryover was 0.1%. Plain sample tubes were a source of aberrant results with routine components. Using ethylenediaminetetraacetic acid tubes the analyzer gave results greater than 1 × 106 /unit in 2.7% of cases compared with 1.4% by flow cytometry, but overall results were within specification, with more than 90% of components having rWBC values below the limit. All incidences of poor leukoreduction, with flow cytometry results greater than 13 rWBCs/µL were correctly identified, with an excellent correlation between results (R2 = 0.9818). CONCLUSION: The analyzer demonstrated acceptable performance characteristics for enumeration of rWBCs; consequently, additional multisite evaluations are warranted.

Washed red cells: theory and practice.

Washing of red cells is sometimes performed to reduce allergic reactions due to contaminating plasma proteins or to reduce the concentration of potassium accumulating in the supernatant of red cells during storage as an alternative to transfusion of fresher red cells in patients at risk of hyperkalaemia. There are a variety of methods for washing red cells, and the laboratory data suggest that variables such as age of red cell before washing, washing method and solution, storage medium and length of storage time after washing can all effect the final red cell quality. Studies suggest that washing removes 90-95% plasma, but the proportion of units below 0·05 mg/dl IgA (equivalent to IgA deficient) is variable dependent upon methods used. Although potassium levels are reduced immediately following washing, the rate of leakage following subsequent storage is method-dependent, requiring careful consideration of shelf life if potassium reduction is the goal. Other markers of red cell quality such as haemolysis are negatively impacted by washing so a reduced shelf life compared to standard red cells is appropriate, especially following irradiation. Data from animal models and clinical studies on possible additional benefits of washing, such as reduced lung or kidney injury, are mixed, ranging from some benefit to some harm, and further studies are warranted.

The effect of variation in donor platelet function on transfusion outcome: a semirandomized controlled trial.

The effect of variation in platelet function in platelet donors on patient outcome following platelet transfusion is unknown. This trial assessed the hypothesis that platelets collected from donors with highly responsive platelets to agonists in vitro assessed by flow cytometry (high-responder donors) are cleared more quickly from the circulation than those from low-responder donors, resulting in lower platelet count increments following transfusion. This parallel group, semirandomized double-blinded trial was conducted in a single center in the United Kingdom. Eligible patients were those 16 or older with thrombocytopenia secondary to bone marrow failure, requiring prophylactic platelet transfusion. Patients were randomly assigned to receive a platelet donation from a high- or low-responder donor when both were available, or when only 1 type of platelet was available, patients received that. Participants, investigators, and those assessing outcomes were masked to group assignment. The primary end point was the platelet count increment 10 to 90 minutes following transfusion. Analysis was by intention to treat. Fifty-one patients were assigned to receive platelets from low-responder donors, and 49 from high-responder donors (47 of which were randomized and 53 nonrandomized). There was no significant difference in platelet count increment 10 to 90 minutes following transfusion in patients receiving platelets from high-responder (mean, 21.0 × 109/L; 95% confidence interval [CI], 4.9-37.2) or low-responder (mean, 23.3 × 109/L; 95% CI, 7.8-38.9) donors (mean difference, 2.3; 95% CI, -1.1 to 5.7; P = .18). These results support the current policy of not selecting platelet donors on the basis of platelet function for prophylactic platelet transfusion.

Effect of storage of plasma in the presence of red blood cells and platelets: re-evaluating the shelf life of whole blood.

BACKGROUND: There is renewed interest in administering whole blood (WB) for the resuscitation of patients with bleeding trauma. The shelf life of WB was established decades ago based on the viability of red blood cells. However, plasma quality during WB storage is not established. STUDY DESIGN AND METHODS: White blood cell- and platelet-reduced WB (WB-PLT) was prepared using standard processes and compared to WB processed using a platelet-sparing WBC reduction (WB + PLT) filter. WB (± PLT) was held at 2 to 6°C for 35 days alongside control units of red blood cells (RBCs) in saline, adenine, glucose, and mannitol and liquid plasma. A series of assays explored the coagulation potential and RBC quality. RESULTS: While fibrinogen and α2-antiplasmin remained unaffected by storage, other factors varied between components or over time at 2 to 6°C. At 14 days factor V, factor VII, α2 -antiplasmin and free protein S antigen remained on average greater than 0.50 IU/mL or 50%, as appropriate, in WB ± PLT. Factor VIII was on average 0.49 IU/mL in WB+PLT, and 0.56 IU/mL for WB-PLT. Free protein S activity decreased significantly in all arms but remained on average greater than 40% at Day 14. Contact activation was not demonstrated before Day 14. Thrombin generation in plasma remained relatively stable to Day 35 in all arms. CONCLUSIONS: Clotting factor activity remained at or above a mean of 0.5 IU/mL, or 50%, at Day 14 for factor V, factor VII, factor VIII, free protein S, fibrinogen, and α2-antiplasmin in all arms. Further data on platelet function in WB+PLT is needed to inform its shelf life.

Thawing times and hemostatic assessment of fresh frozen plasma thawed at 37°C and 45°C using water-bath methods.

BACKGROUND: The Barkey Plasmatherm (BP; Barkey GmbH & Co. KG) can thaw plasma at 37°C and 45°C. No studies have assessed thawing times or hemostatic qualities of plasma thawed at 45°C with BP. This study assessed fresh frozen plasma (FFP) thawing times with use of BP at 37°C and 45°C and Thermogenesis ThermoLine (TT; Helmer Scientific) at 37°C and compared the hemostatic quality of LG-Octaplas (Octapharma) with use of BP at 37°C and 45°C with TT at 37°C. STUDY DESIGN AND METHODS: The thawing time of FFP (pairs or fours) was assessed using BP at 37°C and 45°C (not prewarmed and prewarmed) and TT at 37°C. Hemostasis was assessed in LG-Octaplas at 5 minutes, 24 hours, 48 hours, and 120 hours after thawing with use of the three methods. RESULTS: Thawing time for two units was 13.44 minutes using TT, the same as using BP at 37°C (12.94 min not prewarmed; 12.20 min prewarmed) or 45°C (12.38 min not prewarmed), but longer than using BP prewarmed to 45°C (11.31 min, p < 0.001). Thawing time for four units was 13.41 minutes using TT, shorter than using BP at 37°C (17.19 min not prewarmed, 18.47 min prewarmed; both p < 0.001) or 45°C (15.03 min not prewarmed, p = 0.012; 15.22 min prewarmed, p = 0.004). There was no reduction in hemostatic markers in LG-Octaplas with use of BP at 37°C or 45°C compared to TT. CONCLUSION: BP is quicker than TT by 2 minutes when thawing two units of FFP if it is prewarmed to 45°C. BP is slower than TT by at least 2 minutes when thawing four units of FFP at 37o C. There was no significant difference in the hemostatic qualities of plasma whether thawed at 37°C or 45°C.