title: Storage of interim platelet units for 18 to 24 hours before pooling: in vitro study.
abstract: BACKGROUND
  The Atreus 3C system (CaridianBCT) automatically produces three components from whole blood (WB), a red blood cell (RBC) unit, a plasma unit, and an interim platelet (PLT) unit (IPU) that can be pooled with other IPUs to form a PLT dose for transfusion. The Atreus 3C system also includes a PLT yield indicator (PYI), which is an advanced algorithm that provides an index that is shown to correlate well with the amount of PLTs that finally end up in the IPU bag. The aim of our in vitro study was to compare the effects of holding WB overnight versus processing WB fresh (2-8 hr), both with 18- to 24-hour storage of the IPUs before pooling into a transfusable PLT dose.
  
  
  METHODS
  WB was processed either fresh (within 8 hr after collection, Atreus F) or after overnight storage (14-24 hr, Atreus S) without agitation at 22 ± 2 °C. After a subsequent resting time of 18 to 24 hours on a flat-bed shaker, five IPUs were selected for pooling with 200 mL of PAS II for in vitro quality assessments during a 7-day storage period (n = 10 in each arm). IPUs were selected for pooling using the PYI of the Atreus 3C system.
  
  
  RESULTS
  During storage, the glucose concentration was lower (p < 0.05) and the lactate concentration was higher (p < 0.05) in Atreus S pools, but no differences in the glucose consumption rate were noted. Adenosine triphosphate levels and hypotonic shock response reactivity were higher in Atreus S (p < 0.05). No significant differences in PLT counts, contents, mean PLT volume, lactate dehydrogenase, pO(2) , pCO(2) , extent of shape change, and CD62P between groups were detected. pH was maintained higher than 6.8 (Day 7). With exception of 2 units in the Atreus S arm, swirling remained at greater than 2 in all units at all times.
  
  
  CONCLUSIONS
  Our results suggest that PLTs prepared from fresh or overnight-stored WB and pooled after 18 to 24 hours meet necessary in vitro criteria without any relevant differences between both groups. Using the PYI, comparable yields can be obtained between WB processed within 2 to 8 hours and WB stored overnight.
authors.affiliation: Department of Clinical Immunology and Transfusion Medicine, Karolinska University Hospital, Stockholm, Sweden. per.sandgren@karolinska.se
authors.forename: Per
authors.initials: P
authors.lastname: Sandgren
authors.forename: Geert
authors.initials: G
authors.lastname: van Waeg
authors.forename: Caroline
authors.initials: C
authors.lastname: Verheggen
authors.forename: Agneta
authors.initials: A
authors.lastname: Sjödin
authors.forename: Hans
authors.initials: H
authors.lastname: Gulliksson
mesh_terms: D001786:Blood Glucose / Q000032:analysis; D001792:Blood Platelets / Q000166:cytology* / Q000378:metabolism; D001793:Blood Preservation / Q000009:adverse effects*; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D010976:Platelet Count; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D019344:Lactic Acid