Vox Sanguinis International Forum on the use of prehospital blood products and pharmaceuticals in the treatment of patients with traumatic haemorrhage.

While specific practices and transported blood products vary around the world, most of the respondents in this International Forum transported at least one blood product for the transfusion to bleeding patients en route to the hospital. The most commonly carried product was RBCs, while the use of whole blood will likely increase given the recent reports of its successful use in the civilian setting, and because of the change in the AABB's Standards regulating its use. It will be interesting to see if plasma use in the prehospital setting becomes more widely used given today's enhanced appreciated of the coagulopathy of trauma and plasma's beneficial effect in reversing it, and if blood products are transported to the scene of injury by more vehicles, that is, not just predominantly in helicopters. It was not surprising that TXA is being widely administered as close to the time of injury as possible given its potential benefit in these patients. This International Forum highlights the importance of focusing attention on prehospital transfusion management with a need to further high­quality research in this area to guide optimal resuscitation strategies.

Femtogram Resolution of Iron Content on a Per Cell Basis: Ex Vivo Storage of Human Red Blood Cells Leads to Loss of Hemoglobin.

The magnetic characteristics of hemoglobin (Hb) changes with the binding of dioxygen (O2) to the heme prosthetic groups of the globin chains: from paramagnetic ferrous Hb to diamagnetic ferrous oxyhemoglobin (oxyHb) with reversibly bound O2, or paramagnetic ferric methemoglobin (metHb). When multiplied over the number of Hb molecules in a red blood cell (RBC), the effect is detectable through motion analysis of RBCs in a high magnetic field and gradient. This motion is referred to as magnetophoretic mobility, which can be conveniently expressed as a fraction of the cell sedimentation velocity. In this Article, using a previously developed and reported instrument, cell tracking velocimetry (CTV), we are able to detect difference in Hb concentration in two RBC populations to a resolution of 1 × 107 Hb molecules per cell (4 × 107 atoms of Fe per cell or 4-5 femtograms of Fe). Similar resolution achieved with inductively coupled plasma-mass spectrometry requires on the order of 105-106 cells and provides an average, whereas CTV provides a measurement for each cell. CTV analysis revealed that RBCs lose, on average, 17% of their Hb after 42 days of storage, the maximum FDA-approved length of time for the cold storage of RBCs in additive solution. This difference in Hb concentration was the result of routine RBC storage; clinical implications are discussed.

Measurement of haemolysis markers following transfusion of uncrossmatched, low-titre, group O+ whole blood in civilian trauma patients: initial experience at a level 1 trauma centre.

BACKGROUND/OBJECTIVES: The safety of administering uncrossmatched, group O, cold-stored, whole blood (cWB) during civilian trauma resuscitation was evaluated. METHODS/MATERIALS: Male trauma patients with haemorrhage-induced hypotension who received leuko-reduced uncrossmatched group O+, low titre (<50) anti-A and -B, platelet-replete cWB during initial resuscitation were included. The biochemical markers of haemolysis (lactate dehydrogenase, total bilirubin, haptoglobin, creatinine, serum potassium) were measured on the day of cWB receipt (day 0), and over the next 2 days, reports of transfusion reactions and total blood product administration in first 24 h of admission were recorded. RESULTS: There were 27 non-group O and 17 group O cWB recipients. The median number of cWB units transfused was 1 [interquartile range (IQR): 1-2] in both groups. The median day 0 post-transfusion serum total bilirubin concentration, although still in the normal range, was higher in the non-group O versus group O recipients (1·4 versus 0·5 mg/dL, P < 0·01). There were no significant differences in any of the other biochemical parameters at any other time point. Non-group O recipients received a median of 3 times more red blood cell (RBC) units compared with group O recipients (P = 0·01 RBCs), likely explaining the bilirubin difference on day 0. The median volume of ABO-incompatible plasma transfused to non-group O recipients was 600 mL (IQR: 300-1140 mL). There were no reports of adverse events related to the cWB transfusion in either group. CONCLUSIONS: Administration of ≤2 units of cWB in civilian trauma resuscitation was not associated with clinically significant changes in laboratory haemolysis markers. Efficacy will be determined when larger quantities are transfused.

I am the 9%: Making the case for whole-blood platelets.

Over the last 15 years, there has been a trend in the United States towards the increasing use of apheresis platelet (AP) concentrates over whole-blood-derived platelets (WBP). Although 1-h- and 24-h-corrected count increments tend to be higher with AP, this does not translate into improved haemostatic efficiency when used to prevent bleeding in haematology/oncology patients. WBP expose the recipient to more donors than apheresis products. However, recent studies have shown no significant differences in the rates of bacterial contamination, human leukocyte antigen alloimmunisation, RhD alloimmunisation, transfusion-related acute lung injury or febrile non-haemolytic transfusion reactions between these two products. Given the overall low rates of virally contaminated units in the era of nucleic acid testing and rigorous donor screening, the difference in donor exposures of 4-6 vs 1 has minimal clinical relevance. Although studies point to a marginally increased risk of donor adverse events associated with WBP, the absolute risk is too miniscule to act as a deterrent to making whole-blood donations. Both types of platelet concentrates should therefore be considered clinically equivalent; in this light, the most responsible use of the community donor resource pool, which both optimises the utility of a whole-blood donation and meets the clinical needs of thrombocytopenic recipients, is to have a mix of both types of platelet products so as to mitigate the risk of shortages.

Whole blood for the acutely haemorrhaging civilian trauma patient: a novel idea or rediscovery?

The concept of whole blood (WB) as a treatment modality for trauma patients requiring transfusion therapy is not new. Successfully employed in the early 20 century, WB was the product of choice for military trauma resuscitation until the advent of component therapy changed the landscape of transfusion medicine. However, the recognition of the success of WB in the military operational setting has provided some enthusiasm to explore its revival as a cold-stored option in the civilian trauma resuscitation sector. Concerns continue to exist over potential limitations for its application in regards to the efficacy of platelets after cold storage, the risk of haemolytic transfusion reactions following the transfusion of un-cross-matched WB and the logistical issues for civilian blood banks in providing WB. This review aims to reconcile these concerns with data available in the literature, with a view to establishing that there is in vitro evidence supporting the haemostatic effects of cold-stored WB as a potential therapeutic option in both the pre-hospital and in-hospital civilian trauma resuscitation settings.

Excessive quantities of red blood cells are issued to the operating room.

OBJECTIVES: To determine what percentage of red blood cell (RBC) units that were issued to the operating room (OR) were returned unused, and to determine how often all of the RBCs that were issued for a patient were returned unused using the institution's maximum surgical blood ordering schedule (MSBOS) as a guide. BACKGROUND: The MSBOS provides guidelines for blood ordering, but is merely a suggestion for the ordering clinicians. This study examined how closely ordering practices followed the MSBOS, and how often ordered RBCs were actually transfused. METHODS: For a 4-week period, RBC issue and utilization data were collected on elective surgery patients who were eligible for electronic cross-match at a tertiary care hospital. These data were compared to the MSBOS. RESULTS: There were 1350 surgical procedures performed. Of these cases, 439 patients had a type and screen (T&S) performed, and 215/439 (49%) patients had at least 1 RBC issued during their case. To these 215 patients, 742 RBC units were issued and 537/742 (72%) of these units were returned to the blood bank unused. In 152/215 (71%) cases with issued RBCs, all of the RBCs were returned to the blood bank unused. Amongst the surgical categories in this study, the percentage of cases where none of the issued RBCs were transfused ranged from 38 to 93%. CONCLUSIONS: Significant numbers of RBC units are issued but not transfused during surgery. Involving the surgical team in the blood issuing process and using a data-driven MSBOS may reduce the number of unused units.

A novel cis-AB variant allele arising from a de novo nucleotide substitution c.796A>G (p.M266V) in the B glycosyltransferase gene.

BACKGROUND: Cis-AB, a rare ABO variant, is the result of a mutated ABO gene that produces a glycosyltransferase enzyme with dual A and B glycosyltransferase activity. It may lead to ABO discrepancies and a delay in establishing the blood group. To date, there have been no reports of a de novo mutation leading to a cis-AB allele. OBJECTIVES AND METHODS: Sequencing of the ABO gene using blood and hair follicle cells from the proposita were performed along with blood from her parents. To establish maternity and paternity, short tandem repeat (STR) analysis was also performed. The A and B enzyme activities of the novel enzyme were measured in an in vitro expression study. RESULTS: A novel cis-AB allele arising from nucleotide substitution c.796A>G (p.M266V) in the B glycosyltransferase gene were discovered in the blood and hair follicle cells from the proposita, which was absent from her parents. In all 15 autosomal STR loci analysed, the probability of maternity and paternity were 0.999999 and 0.999989, respectively. The novel enzyme created 33.1% and 60.2% of A and B antigen compared to wild type A and B glycosyltransferases. CONCLUSION: A novel mechanism leading to a cis-AB allele was discovered.

Relative IgA-deficient recipients have an increased risk of severe allergic transfusion reactions.

BACKGROUND: Absolute IgA deficiency is the most common immunodeficiency in the Western world. These patients are at risk of severe allergic reactions when receiving a transfusion with a plasma-containing blood product. However, it is unclear whether patients with relative IgA deficiency, that is levels below detection on routine assays, are also at risk of severe reactions. This retrospective study evaluated the number of severe allergic transfusion reactions in relative IgA-deficient patients who were transfused with unwashed blood products. STUDY DESIGN AND METHODS: Patients who had an IgA measurement performed for any reason over a 10-year period were compared with a list of transfusion recipients over the same period. Those who had both an IgA measurement and a transfusion were then compared with the transfusion reaction database to determine whether an allergic reaction had been reported, and if so, the severity of the reaction. Patients with IgA concentrations of <7 mg/dL were defined as relative IgA deficient. RESULTS: Of the 22 362 IgA measurements performed on 19 737 patients over 10 years, a total of 168 relative IgA-deficient patients were identified; 39 of these patients were also transfusion recipients and 4 of 39 (10%) experienced a severe allergic transfusion reaction (SALTR). Eight SALTRs were reported amongst 1545 (0·52%) IgA replete transfusion recipients. CONCLUSION: The significantly increased risk of SALTRs in relative IgA-deficient patients warrants consideration of premedications and/or washing of plasma-containing blood products.

Ascorbic acid improves membrane fragility and decreases haemolysis during red blood cell storage.

BACKGROUND: Changes that occur to red blood cells (RBCs) during routine blood bank storage include decreased deformability, increased haemolysis and oxidative damage. Oxidative injury to the RBC membrane and haemoglobin can affect changes in shape and deformability. Ascorbic acid (AA) is an antioxidant that maintains haemoglobin in a reduced state and minimises RBC oxidative injury. We hypothesised that AA would improve membrane fragility and decrease haemolysis during storage. METHODS: Whole blood derived, AS-5 preserved, pre-storage leucoreduced RBC units were exposed to either AA or saline control solutions. Several rheological and biochemical parameters were measured serially during storage, including RBC membrane mechanical fragility, percent haemolysis and methaemoglobin levels. RESULTS: AA exposure significantly reduced mechanical fragility and haemolysis over the entire storage period. The highest two concentrations of AA affected the greatest reductions in mechanical fragility and percent haemolysis. Addition of AA to the RBCs did not significantly alter their biochemical parameters compared to control RBCs incubated with saline. CONCLUSION: AA reduced RBC membrane fragility and decreased haemolysis during storage without adversely affecting other RBC biochemical parameters. The clinical significance of these findings needs to be determined.

ABO-mismatched transfusions are not over-represented in febrile non-haemolytic transfusion reactions to platelets.

ABO-mismatched plasma and platelet (PLT) transfusion have been associated with worse outcomes, including haemolysis and other reactions, compared to recipients of ABO-identical products. The immune complexes that form in a mismatched transfusion have been demonstrated to stimulate pyrogenic cytokine release in vitro. Comparing ABO identical vs. ABO mismatched PLT transfusions, we found no significant difference in the ABO compatibilities between the PLT doses implicated in causing febrile non-haemolytic transfusion reactions (FNHTR) in 162 recipients and both the baseline PLT donor/recipient ABO compatibility (P = 0·67) or the PLTs issued in the 30 days preceding the FNHTR (P = 0·92). ABO-mismatched PLT transfusions do not appear to be aetiological agents of FNHTR in a population routinely receiving both ABO-identical and ABO-mismatched transfusions.

Haemolysis and sublethal injury of RBCs after routine blood bank manipulations.

OBJECTIVES: To determine the extent of RBC sublethal injury in male donor units as measured by both the mechanical fragility index (MFI) and percentage haemolysis after RBCs underwent leucoreduction (LR), irradiation (IRRAD), and washing. BACKGROUND: RBCs frequently undergo post-collection processing to meet certain recipient's special needs. The extent of haemolysis and sublethal injury following these interventions has not been fully characterised. METHODS: Eight to ten day old male, AS-5 RBCs underwent either LR, IRRAD or washing. A control group of male, AS-5 RBCs were unmanipulated. The MFI, percent haemolysis, and plasma free haemoglobin (PFHb) were measured immediately after manipulation and, for a series of irradiated RBCs, 28 days after irradiation (IRRAD28). RESULTS: The MFI of the washed units was significantly higher than unmanipulated, LR, IRRAD, IRRAD28 units (P < 0·0001). The percent haemolysis was highest in the IRRAD28 units (1·4%) followed by the washed units (0·74%); the other three units demonstrated significantly less haemolysis (P < 0·0001). The largest mean total amount of PFHb per unit was found in the IRRAD28 units (500·5 mg/unit) followed by the washed units (149·8 mg/unit); the mean total amount of PFHb in the three other types of units was significantly less than that found in both the IRRAD28 and washed units (P at least < 0·001). CONCLUSION: There is a significant quantity of PFHb in IRRAD28 RBC units, and potentially in washed allogeneic RBC units. Clinical correlation is required to determine if this quantity of PFHb and the transfusion of potentially fragile RBCs causes adverse events.

Menopausal status affects the susceptibility of stored RBCs to mechanical stress.

The mechanical fragility index (MFI) is an in vitro measure of sublethal injury to RBCs. In our previous experiments, we demonstrated that an increase in sublethal injury (increasing MFI) was a component of the RBC storage lesion, and that the MFI was significantly higher amongst the RBC units from male donors compared to pre-menopausal female donors during storage. It was hypothesized that hormonal or menstrual factors contributed to this difference. In this study, we found that RBC units donated by post-menopausal women demonstrated an MFI that was significantly higher than those donated by pre-menopausal women throughout storage.

The use of the mechanical fragility test in evaluating sublethal RBC injury during storage.

BACKGROUND: The mechanical fragility index (MFI) is an in vitro measurement of the extent of RBC sublethal injury. Sublethal injury might constitute a component of the RBC storage lesion, thus the MFI was determined serially during routine RBC storage. METHODS: Leucoreduced AS-5- and SAGM-preserved RBCs were stored under routine blood bank conditions. The mechanical fragility (MF) of each unit was serially measured during storage. RESULTS: For both AS-5 and SAGM units, male and female RBCs demonstrated statistically significant increases in the MFI during storage. The MFI was significantly lower in AS-5 units compared to SAGM units throughout storage. Female RBCs had significantly lower MFI vs. male RBCs in both AS-5 and SAGM units at all times. No significant differences in MFI were observed between ABO groups for both genders for AS-5 RBCs. CONCLUSIONS: The MF of RBCs increases during storage. Both gender and preservation solution influenced the MFI; however, the male:female MFI ratios were similar at all time-points and remained stable, suggesting that gender-based biological differences exist independent of storage solution. The MF could be a useful test for evaluating the effect of novel interventions intended to mitigate the susceptibility of RBCs to sublethal injury during storage.

Serial oxygen equilibrium and kinetic measurements during RBC storage.

OBJECTIVES: To contribute to the understanding of the biochemical changes associated with the RBC storage lesion. AIM: To investigate changes in O(2) equilibrium and on/off kinetic rates during routine cold storage. BACKGROUND: As RBCs are stored between 1 and 6°C numerous biochemical changes occur within the RBCs, including changes in the properties of the haemoglobin itself. This study serially analysed for the first time the O(2) equilibrium and on/off kinetic rates across the RBC membrane during routine storage. METHODS/MATERIALS: The oxygen binding (k(on) ) and offloading (k(off) ) constants were measured in fresh RBCs and then in AS-5-preserved RBCs at weekly intervals, along with oxygen equilibrium curves (OECs), 2,3-Diphosphoglycerate (2,3-DPG), p50 and the Hill number (n). RESULTS: The k(on) increased slightly as the 2,3-DPG and p50 decreased during storage, whereas the k(off) remained largely unchanged. The OECs demonstrated the expected increase in O(2) affinity, whereas the Hill number was unchanged during storage. CONCLUSION: In spite of the biochemical, structural and functional changes associated with the storage of RBCs, their in vitro interactions with oxygen were largely preserved through 42 days of storage.