Precise pH measuring of platelet concentrates containing additive solution – the impact of the temperature
Article first published online: 5 JAN 2012
© 2012 The Author(s). Vox Sanguinis © 2012 International Society of Blood Transfusion
Volume 103, Issue 1, pages 49–54, July 2012
How to Cite
Ringwald, J., Luther, R., Zimmermann, R., Strobel, J., Weiss, D. and Eckstein, R. (2012), Precise pH measuring of platelet concentrates containing additive solution – the impact of the temperature. Vox Sanguinis, 103: 49–54. doi: 10.1111/j.1423-0410.2011.01578.x
- Issue published online: 12 JUN 2012
- Article first published online: 5 JAN 2012
- Received: 17 August 2011, revised 14 November 2011, accepted 15 November 2011
- pH measuring;
- platelet components;
- platelet concentrates;
- quality control
Background and Objectives Blood gas analysers measuring pH at 37°C (pH37) are widely used for pH determination of platelet (PLT) concentrates (PCs). For reporting pH at 22°C (pH22), converting of pH37 using the correct conversion factor is mandatory. For PCs stored in PLT additive solution (PAS), such conversion factors are not yet widely available. We studied pH in samples of PCs with different PAS/plasma ratios during warming from 22 to 37°C.
Materials and Methods We measured pH in 39 samples containing modified PAS-III (PAS-IIIM) with a plasma carryover of 20%, 30% or 40% or no PAS-IIIM. Differences between pH22 and pH37 (dpH) were compared within and between study groups. Correlation between pH22 and dpH was tested. Additional measurements in 33 samples with three different PLT counts were performed to study the influence of PLT count on dpH.
Results pH22 and pH37 within each group and dpH or dpH/dT between study groups differed significantly. The dpH was 0·135 ± 0·040, 0·021 ± 0·009, 0·033 ± 0·011 and 0·048 ± 0·017 for samples containing 100%, 20%, 30% or 40% plasma, respectively. Correlation between dpH and pH22 was strong in 100% (r = 0·696, P < 0·001), weaker in 30% and 40% (r = 0·367, P = 0·022 and r = 0·345, P = 0·032, respectively) and not existing in 20% plasma (r = 0·153, P = 0·354). PLT count did not influence the dpH significantly.
Conclusion The dpH is dependent on different PAS-IIIM/plasma ratios and pH range. For precise reporting of pH22, the respective dpH must be used if converting is necessary. Preferably, the pH should be reported at 37°C or measured directly at 22°C.