Till Örebro universitet

BACKGROUND: The use of low-titer O whole blood (LTOWB) is requested in the treatment of major bleeding, initially used in military medicine but now increasingly utilized in civilian prehospital care. The advantage is the administration of a balanced transfusion, red blood cells, coagulation factors, and platelets, in one bag. The challenges are the availability of LTOWB and difficulties in predicting the need in major bleeding, leading to the risk of wastage.

METHODS: This study describes different logistical strategies when implementing whole blood in the Swedish civilian healthcare. The five transfusion centers producing whole blood in Sweden participated, providing experience of the production line, usage, and wastage.

RESULTS: In Sweden, LTOWB is used prehospital in helicopter emergency medical service (HEMS), in one physician-manned rapid response vehicle, and inhospital in three University Hospitals. The logistical strategies to reduce wastage vary but involve the rotation of LTOWB not used prehospital to inhospital use in two centers and the preparation of red blood cell (RBC) units from 1 to 2 weeks old LTOWB in three centers. The number of transfused LTOWB units varies between the centers, and wastage was 0%-13% in 4/5 centers and higher in one center, 34%.

CONCLUSION: It is difficult to predict the need of LTOWB, requested in prehospital emergencies. Aiming for low wastage requires different logistical chains, depending on the local prerequisites. In Sweden, LTOWB is either rotated for use in major bleeding in hospital or prepared to RBC units after 1 week prehospital.

BACKGROUND AND OBJECTIVES: The Nordic region includes Denmark, Finland, Iceland, Norway and Sweden, with a population of >27.5 million. Blood services are managed differently in each country. Current data on platelet concentrate (PC) production methods and capacity are important for developing efficiency and cross-border preparedness.

MATERIALS AND METHODS: Retrospective data for 2018-2022 were collected through an online survey sent to all blood centres producing platelets in the region. Questions focused on collection procedures (aphaeresis [AP] or whole blood [WB]-derived pools), use of bacterial culture screening (BCS) or pathogen reduction (PR), shelf-life, transfusion practices and quality control.

RESULTS: A total of 43 blood centres provided data (83% response), including complete national coverage for Sweden, Finland and Iceland. Between 2018 and 2022, 632,596 PCs were produced at participating centres. Annual PC production was stable over the period. Most PCs were WB pools (77%). Automated separation to produce interim platelet unit (IPU) pools was performed at 19 centres. PR and BCS were used in 17 and 23 centres, respectively. Shelf-life ranged from 5 days (no safety measure) to 7 days (PR or BCS). The number of PCs transfused in the region declined by ~5% from 2018 to 2022.

CONCLUSION: Platelet production methods, including safety measures to prevent bacterial contamination, varied widely in the Nordic region. Harmonization, including the use of PR or BCS with 7-day storage, may contribute to resilient platelet supplies in the region.

Platelets are transfused to patients to prevent bleeding. Since both preparation and storage can impact the hemostatic functions of platelets, we studied platelet concentrates (PCs) with different initial composition in regard to platelet fragmentation and its impact on storage-induced changes in activation potential. Ten whole blood derived PCs were assessed over 7 storage days. Using flow cytometry, platelet (CD41+) subpopulations were characterized for activation potential using activation markers (PAC-1, P-selectin, and LAMP-1), phosphatidylserine (Annexin V), and mitochondrial integrity (DiIC1(5)). Aggregation response, coagulation, and soluble activation markers (cytokines and sGPVI) were also measured. Of the CD41+ events, the PCs contained a median of 82% normal-sized platelets, 10% small platelets, and 8% fragments. The small platelets exhibited procoagulant hallmarks (increased P-selectin and Annexin V and reduced DiIC1(5)). Normal-sized platelets responded to activation, whereas activation potential was decreased for small and abolished for fragments. Five PCs contained a high proportion of small platelets and fragments (median of 28% of CD41+ events), which was significantly higher than the other five PCs (median of 9%). A high proportion of small platelets and fragments was associated with procoagulant hallmarks and decreased activation potential, but, although diminished, they still retained some activation potential throughout 7 days storage.

In flow cytometry, individual cells are investigated. Platelet activation is normally reported in form of percentage of platelets expressing the marker (positive platelets) and/or mean/median fluorescence intensity (MFI) for the entire analyzed population. None of these take into account the variance of the marker expression between individual platelets. This can be obtained as data on coefficient of variation (CV). This study explores if CV provides additional information regarding platelet function. Samples from platelet concentrates (PCs) prepared by apheresis- (n = 13) and interim platelet unit (IPU) technique (n = 26) and stored for 6-7 days were included and compared. Spontaneous- and agonist-induced expression of activation markers (fibrinogen binding and exposure of P-selectin, LAMP-1, and CD63) was investigated as percentage positive platelets, MFI and CV. Spontaneous expression of P-selectin as percentage positive platelets and MFI was higher for IPU PCs than apheresis PCs, which in contrast had higher agonist-induced activation. CV for spontaneous fibrinogen binding and P-selectin exposure was larger for apheresis PCs, while IPU PCs generally had larger CV for P-selectin, LAMP-1, and CD63 after agonist stimulation. Our findings show that CV adds additional information when assessing platelet activation by providing data on the variation in activation responses within the platelet population.