title: Extracellular potassium concentrations in red blood cell suspensions after irradiation and washing.
abstract: BACKGROUND
  Extracellular potassium concentration [K(+)e] increases with duration of red blood cell storage. Sometimes red blood cells (RBC) are washed before transfusion to infants to reduce [K(+)e] of these components. AABB standards permit storage of washed RBCs at 4 degrees C for 24 hours. The [K(+)e] of washed RBCs during storage is not known. Experiments were performed to provide those data.
  
  
  METHODS
  One day after outdating, 26 RBC units were washed without irradiation or before or after irradiation (25 Gy), and [K(+)e] was measured for 24 hours. [K(+)e] was measured also immediately before transfusion of 29 nonoutdated irradiated and washed RBC units.
  
  
  RESULTS
  After washing, [K(+)e] increased in a time-dependent fashion. [K(+)e] increased more rapidly in preparations of irradiated than nonirradiated RBCs. [K(+)e] was less after washing after irradiation (1.6 +/- 0.3, 2.4 +/- 0.3, 3.0 +/- 0.3, 3.6 +/- 0.3. 4.2 +/- 0.4, 5.3 +/- 0.5, 8.6 +/- 1.0, and 14.3 +/- 1.3 mEq/L at 0, 1, 2, 3, 4, 6, 12, and 24 hr; mean +/- SD) than washing before irradiation (p < 0.001). The increase in [K(+)e] during the first 6 hours after washing after irradiation was linear (0.61 +/- 0.08 mEq K(+)/L/hr). The probability of a unit of RBCs having a [K(+)e] greater than 5 mEq per L is 0.0 to 0.2 percent 3 hours after washing irradiated RBCs and 0.0 to 1.1 percent 6 hours after washing nonirradiated RBCs.
  
  
  CONCLUSIONS
  [K(+)e] increases after washing irradiated and nonirradiated packed RBCs. After irradiation and washing, the [K(+)e] for the initial 6 hours can be predicted from the [K(+)e] immediately after washing. There is a low probability that a unit of RBCs would have a [K(+)e] greater than 5 mEq per L during 6 hours of storage at 4 degrees C after washing if the cells are not irradiated and for 3 hours if the cells are irradiated.
authors.affiliation: Department of Anesthesia, University of California, San Francisco, California 94143-0648, USA. weiskopf@anesthesia.ucsf.edu
authors.forename: Richard B
authors.initials: RB
authors.lastname: Weiskopf
authors.forename: Stephanie
authors.initials: S
authors.lastname: Schnapp
authors.forename: Kathryn
authors.initials: K
authors.lastname: Rouine-Rapp
authors.forename: Alan
authors.initials: A
authors.lastname: Bostrom
authors.forename: Pearl
authors.initials: P
authors.lastname: Toy
mesh_terms: D001793:Blood Preservation; D017707:Erythrocyte Transfusion; D004912:Erythrocytes / Q000737:chemistry* / Q000528:radiation effects*; D006801:Humans; D011188:Potassium / Q000097:blood*; D013535:Suspensions
chemical_list: D013535:Suspensions; D011188:Potassium