engleski

Tourniquet influence on ionized calcium determination: to be avoided or to be applied? 4th EFLM-BD European Conference on Preanalytical Phase

BACKGROUND-AIM: Recommendations regarding tourniquet application for ionized calcium determination (iCa) deserve proper consideration. The aim of this study was to compare the iCa values obtained from samples collected without and with tourniquet application depending on the different release time of the tourniquet. METHODS: The study included two groups ; in the first group two blood samples were collected from 30 volunteers (23 women and 7 men), median age (range) 26 (18-58): one without tourniquet application and one from the other arm with a tourniquet released immediately after the blood has flown. In the second group, two blood samples were drawn from 30 volunteers (22 women and 8 men), median age (range) 34 (26-62) in the same way, but the tourniquet was released after complete tube filling. The blood samples were drawn from the antecubital vein directly into vacuum tubes with gel and clot activator. All tubes were completely filled, centrifuged according to the manufacturer’s instructions and left at room temperature until analysis. iCa was measured by potentiometric method on the RapidLab 348EX analyzer (Siemens, Suffolk, UK). Clinically significant difference was evaluated according to RiliBÄK’s criteria (acceptable deviation < 7.5%). Passing-Bablok regression and Bland- Altman plot were analyzed in MedCalc 14.8.1 (Ostend, Belgium). RESULTS: Passing-Bablok regression showed the minimum constant error between samples collected in the first group: y = 0, 01(0, 01- 0, 11) + 1, 00(0, 92-1, 00)x. In the second group, no constant or proportional error was found: y = 0, 00(-0, 12- 0, 00) + 1, 00(1, 00-1, 09)x. Bland- Altman plot did not show any clinically significant difference for iCa in samples collected in both groups when compared to RiliBÄK’s criteria. CONCLUSION: There is no clinically significant difference between samples collected for iCa determination without and with tourniquet application.

tourniquet, ionized calcium, preanalytical phase

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