title: Reduction in potassium concentration of stored red blood cell units using a resin filter.
abstract: BACKGROUND
  Hyperkalemia is a serious complication of rapid and massive blood transfusion due to high plasma potassium (K) in stored red blood cell (RBC) units. A potassium adsorption filter (PAF) was developed in Japan to remove K by exchanging with sodium (Na). We performed an in vitro evaluation of its efficacy and feasibility of use.
  
  
  METHODS
  Three AS-3 RBC units were filtered by each PAF using gravity; 10 PAFs were tested. Blood group, age, flow rate, and irradiation status were recorded. Total volume, K, Na, Cl, Mg, total Ca (tCa), RBC count, hemoglobin (Hb), hematocrit (Hct), and plasma Hb were measured before and after filtering each unit. Ionized Ca (iCa), pH, and glucose were measured for some units.
  
  
  RESULTS
  After filtration, the mean decrease in K was 97.5% in the first RBC unit, 91.2% in the second unit, and 64.4% in the third unit. The mean increases in Na, Mg, and tCa were 33.0, 151.4, and 116.1%, respectively. iCa and pH remained low; glucose was unchanged. RBC count, Hb, and Hct decreased slightly after filtration of first units; plasma Hb was unchanged. After filtration, there was no visual evidence of increased hemolysis or clot formation.
  
  
  CONCLUSIONS
  The PAF decreased K concentration in stored AS-3 RBC units to minimal levels in the first and second RBC units. Optimally, one filter could be used for 2 RBC units. Although Na increased, the level may not be clinically significant. PAF may be useful for at-risk patients receiving older units or blood that has been stored after gamma irradiation.
authors.affiliation: Transfusion Medicine Division, Department of Pathology, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA. yamadac@umich.edu
authors.forename: Chisa
authors.initials: C
authors.lastname: Yamada
authors.forename: Eugenie S
authors.initials: ES
authors.lastname: Heitmiller
authors.forename: Paul M
authors.initials: PM
authors.lastname: Ness
authors.forename: Karen E
authors.initials: KE
authors.lastname: King
mesh_terms: D004912:Erythrocytes / Q000737:chemistry*; D005374:Filtration / Q000379:methods*; D006801:Humans; D011188:Potassium / Q000737:chemistry*
chemical_list: D011188:Potassium