To find a suitable mode of agitation for the preparation and storage of platelet concentrates (PC), we evaluated the effects of a newly designed rotary motion flat-bed agitator on the resuspension of platelets and maintenance of platelet integrity during storage, in comparison with two conventional types of agitators, the reciprocal flat-bed and elliptical agitators. PC were stored at 20-24C for 72 hours under agitation, and changes in pH, collagen aggregation, hypotonic shock response,

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... gy score and lactate dehydrogenase (LDH) discharge were measured. The percentage of PC resuspended after 16 hours of elliptical, rotary and reciprocal agitaion was 85%, 82% and 77%, respectively. The pH of PC was maintained at 7.1 to 7.5 for 72 hours with any mode of agitation, but the pH varied more widely in the reciprocal group than in the other two groups. The two types of flat-bed agitation showed better preservation of platelets than elliptical agitation as evaluated by collagen aggregation. The morphology scores of PC stored on the rotary agitator were highest among the three groups after 72 hours of storage. The greatest LDH discharge was observed in PC stored on the elliptical rotaor. These data indicate that the rotary mode is more efficient than the reciprocal mode and causes less damage to platelets due to mechanical stress than the elliptical mode. We consider the rotary mode of flat-bed agitation to be preferable for preparing and storing PC.