Discrepant post-filter ionized calcium concentrations by 2 common gas analyzers in continuous renal replacement therapy using regional citrate anticoagulation: another piece of the puzzle

During continuous veno-venous hemodialysis with regional citrate anticoagulation, ionized calcium (iCa) measurements in pre- and post-filter samples are used to adjust flows. Post-filter iCa target concentrations within a low range (0.25–0.34 mmol/L), blood gas analyzers (BGAs) mainly calibrated for physiological values (1.12–1.20 mmol/L). Bias between BGAs these low-value leads errors adjusting the dose,1,2 yet current anticoagulation protocol is worldwide despite lack of standardization.