Background: The air bubbles and foam that develop during the preparation of platelet units have traditionally been considered to interact with the platelets, causing activation and release reactions. However, there actually seems to be no data available concerning the platelet damage that may occur as a result of air bubbles and foam present in the final unit. In this in vitro study we, therefore, investigated the effects of not removing air bubbles/foam from final platelet units, by measuring in vitro parameters during a 7-day storage period.
Design and methods: Platelet samples (n=8) from eight pools of 12 buffy-coats were aliquoted and prepared with the OrbiSac system for storage with (test) or without (reference) air bubbles/foam included in the final units. The metabolic, cellular and activation parameters of all units, comprising approximately 30% plasma and 70% SSP+ platelet additive solution, were analysed during the 7-day storage period.
Results: Differences in platelet counts and contents between the test and reference units were detected throughout storage (p<0.05 at day 5 and p<0.01 at day 7). Lactate dehydrogenase increased during storage in the test units and was significantly higher than in the reference units (p<0.01 from day 5). The hypotonic shock response was greater in the reference units (p<0.05 on day 2 and p<0.01 from day 5). The extent of shape changes was less in the test units (p<0.05 until day 5 and p<0.01 on day 7). CD62P was higher in the test units (p<0.05 on day 7). CD42b decreased in all units but was lower in the test units (p<0.01 on day 5). CD41, CD61 and PAC-1 showed no difference throughout storage between the units (p=NS). Aggregates were visible (day 7) and occurred in three of the test units. pH was maintained at >6.8 (day 7) and swirling remained at the highest level (score =2) for all units throughout storage.
Conclusions: This study shows that storage with air bubbles/foam causes considerable enhancement of disintegration of platelets. In addition, various in vitro parameters of the platelets remaining seem to be negatively affected. The results of this study suggest that platelets should be stored without air bubbles/foam, given that these cause increased disintegration of platelets.