The effects of pH and agitation on platelet preservation.

Platelet concentrates made with an initial pH of 7.85 or 6.85 by addition of alkali or acid were stored at 22 degrees C on tumbler or horizontal agitators. The combination of a high pH and use of a tumbler rotator was associated with a 40 percent reduction in platelet count, fragmentation of platelets, release of lactate dehydrogenase, and a marked loss in response to adenosine diphosphate. Similar, but less striking changes occurred in acidified platelet concentrates stored on the tumbler rotator. Preservation was good for both alkaline and acidified concentrates stored on the horizontal agitator. These in vitro studies showed that, even at a pH of up to 7.7, gently agitated platelets were relatively undamaged for up to 60 hours, while vigorous agitation destroyed platelets at the same pH.