title: Noninvasive measurement of pH in platelet concentrates with a fiber optic fluorescence detector.
abstract: BACKGROUND
  Stored platelets (PLTs) are metabolically active, resulting in a decrease of pH during storage. The pH of PLT concentrates (PCs) is recognized as a measure of quality, and pH limits are set by regulatory bodies. A pH sensor was built into a PLT storage container, and the feasibility of testing pH using a noninvasive fluorescent measurement method was evaluated.
  
  
  METHODS
  A citrated polyvinylchloride (PVC) PLT storage container with pH sensor insert was made and evaluated for biocompatibility during PLT storage and on pH reading accuracy, reproducibility, and durability. A noninvasive fluorescence reader was tested versus syringe-based sampling and subsequent measurement with a blood gas analyzer (BGA). The effect of interfering substances in plasma on the accuracy of this optical measurement was tested. Calibration and accuracy of the pH sensor were determined in both phosphate-buffered saline and in PCs.
  
  
  RESULTS
  The citrated PVC storage container with pH sensor insert showed good storage properties for 300 mL of pooled buffy coat PLTs in plasma over 7 days. The pH sensor was easy to use and tracked pH(22) in the range of 6.2 to 7.8 over 11 days of storage. Accuracy in PCs was 0.08 pH units measured at 22 degrees C when calibrated against a BGA.
  
  
  CONCLUSIONS
  The storage container with integrated pH sensor and noninvasive reader allows pH of PCs to be tracked over time in a noninvasive manner.
authors.affiliation: Blood Cell Storage Inc (BCSI), Seattle, WA, USA.
authors.forename: Mike W
authors.initials: MW
authors.lastname: Reed
authors.forename: Steve
authors.initials: S
authors.lastname: Geelhood
authors.forename: Lynn M
authors.initials: LM
authors.lastname: Barker
authors.forename: Randy
authors.initials: R
authors.lastname: Pfalzgraf
authors.forename: Richard
authors.initials: R
authors.lastname: Vlaar
authors.forename: Eric
authors.initials: E
authors.lastname: Gouwerok
authors.forename: Iris M
authors.initials: IM
authors.lastname: De Cuyper
authors.forename: Paul
authors.initials: P
authors.lastname: Harris
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Verhoeven
authors.forename: Dirk
authors.initials: D
authors.lastname: de Korte
mesh_terms: D001792:Blood Platelets / Q000378:metabolism*; D002138:Calibration; D005336:Fiber Optic Technology / Q000295:instrumentation*; D005470:Fluorometry; D006801:Humans; D006863:Hydrogen-Ion Concentration