['The DiaMed Impact R tests platelet function under close to physiological flow conditions using cone and plate technology. An image analyser quantifies the adhered platelets and results are expressed as percentage of well surface covered by aggregates (SC %) as an index of adhesion and average size of the aggregates (AS microm(2)) as an index of aggregation. The machine is designed to use whole blood and the aim of this study was to determine if it could be used to assess platelet function in platelet concentrates (PC).', 'Platelet concentrates were mixed with various ratios of platelet-poor plasma (PPP) or ABO-compatible routine leucoreduced red cells in saline-adenine-glucose-mannitol. The effects of platelet counts, haematocrit, shear rate and time of activation upon SC and AS were evaluated to identify optimized assay conditions. Routine PCs were then tested on Days 2, 5 and 7. Samples were also stored at 4 or 37 degrees C for 1 to 2 h before assay to see if function was altered.', 'Platelet concentrate in PPP resulted in no detectable platelet adhesion. However, addition of red cells to PC resulted in measurable platelet adhesion and aggregation. Optimal conditions were identified as shear rate of 1800 per second, 4-min activation, platelet count between 250 and 400 x 10(6) per ml, haematocrit between 30 and 40%. When stored PCs were tested under these conditions we observed median values of 8.2% for SC and 32.7 microm(2) for AS at 2 days, which reduced to 6.9% and 25.0 microm(2), respectively, after 5-day storage and 6.8% and 21.0 microm(2) after 7 days.'] Does use of the DiaMed Impact R to test platelet function in stored platelet concentrate?