Background and ObjectivesPlatelet (PLT) aggregates can occur during or after PLT component processing. However, very few reports investigating the phenomenon and its clinical significance have been published. In this review, currently available information about aggregates in PLT products is summarized and possible causal factors as well as preventive strategies are discussed.Materials and MethodsA review of the MEDLINE (R) database for relevant publications from 1960 to May 2013 was conducted.ResultsIt is well known that PLT aggregates may occur during or after the PLT product preparation process. These aggregates normally dissipate with rest and agitation. However, in some rare cases, the aggregates do not dissipate within 24h and can persist up to the end of storage. Exposure to low temperature, low pH, short resting period after collection, different collection systems, presence of bubbles or foam inside the PLT bag, PLT-container interactions, proper product mixing and donor-dependent variables may have an impact on the formation of PLT aggregates. Although publications are rare, the presence of small numbers of PLT aggregates appears to have only limited impact on PLT in vitro quality. Furthermore, data on the clinical impact of PLT aggregates are lacking.ConclusionDespite the fact that PLT aggregates occur in PLT products, published data on this topic remain scant. Considering the concern of clinicians about this phenomenon, more studies are needed which should focus on the possible clinical impact of such aggregates and precautions to avoid PLT aggregate formation in PLT products.

Background and Objectives Lowering the plasma content in single‐donor platelet (PLT) concentrates well below 30% implies the need to collect platelets at very high concentrations. Trima Accel (TA) is validated for collection below 4000 × 103 PLTs/µl. We evaluated its performance at 5000 × 103 PLTs/µl.Materials and Methods Twenty blood donors underwent apheresis with TA twice collecting either a hyperconcentrated or a standard single‐donor platelet concentrate with a target platelet concentration of 5000 or 1200 × 103 PLTs/µl, respectively. We analysed the collection efficiency, the collection rate and the quality of the collected by‐plasma.Results We collected 20 hyperconcentrated and 20 standard units containing 2·56 ± 0·5 and 3·39 ± 0·4 × 1011 PLTs at a concentration of 4518 ± 978 and 1374 ± 166 × 103 PLTs/µl in 45 ± 8 and 39 ± 6 min resulting in a collection efficiency of 47·5 ± 10·0 and 70·7 ± 7·9% and a collection rate of 5·9 ± 1·4 and 8·8 ± 1·5 × 109 PLTs/min, respectively (all results expressed as mean ± standard deviation). The collected by‐plasma showed a very high grade of cell purity and a satisfactory recovery of the clotting factors.Conclusion Although TA is a suitable device for PLT collection at very high concentrations, improvements are desirable to further increase the productivity above its currently validated upper collect concentration limit.

Background and Objectives Aside from new software the blood cell separator TRIMA (GambroBCT) also received a newly designed separation chamber offering a novel single stage separation technology, called Trima Accel. We evaluated this new system focusing on productivity and donor comfort by comparing it to the previous version (Trima version 4) in collecting single-donor platelet concentrates (SD-PCs) and plasma.Materials and Methods Each of 20 donors underwent platelet apheresis using both devices. We compared the collection efficiency (CE), the collections rate (CR), the volume of the collected plasma and the residual leukocytes. Furthermore we compared donor comfort in terms of duration of the donation, flow of citrate back to the donor and platelet and whit blood cell (WBC) loss.Results While the number of collected platelets and the platelet concentration did not differ significantly between both techniques the time of the procedure was reduced by 15.6% with Trima Accel. This results in an increase of the CR and CE of 25% and 15% respectively when using Trima Accel. Log normal probability plotting of WBC counts showed that both techniques complied with the European and the US leukoreduction guidelines. The mean flow of ACDA to the donor perminute and per litre blood volume was also reduced by 20%.Conclusion These data show that the Trima Accel represents a further improvement in apheresis platelet production with a better productivity and donor comfort, especially regarding the mean flow of ACDA to the donor.

Background and Objectives A multicentre trial was set up to evaluate the performance of a new leucodepletion protocol. Materials and Methods Filtration at high haematocrit was started during collection of red blood cell (RBC) products by apheresis with Trima. SAG‐M was added after filtration through the filter. Haematocrits and haemoglobin of the filtered RBCs were measured. Residual leucocytes were determined by Nageotte counting. Results One‐hundred and forty seven procedures were carried out. The haematocrit and haemoglobin contents were 57·3 ± 3·0% and 55·1 ± 4·3 g/unit, respectively. All products showed low residual leucocyte levels (≤ 0·75 × 10 6 /unit; 99·31% < 1 × 10 6 ). Conclusion Immediate, on‐line, high‐haematocrit filtration of red cells collected on Trima resulted in leucoreduced RBCs, which met the AABB and Council of Europe criteria.