The possibility of using effluent ionized calcium to assess regional citrate anticoagulation in continuous renal replacement therapy.

This study aimed to investigate whether effluent ionized calcium was an appropriate indicator to assess anticoagulant effect in continuous renal replacement therapy with regional citrate anticoagulation instead of post-filter ionized calcium. In total, 48 paired samples of effluent fluid and post-filter blood were obtained from critically ill patients who required continuous renal replacement therapy. All samples were taken for ionized calcium measurements and were assessed by point-of-care analyzer. Correlations and agreements between two methods were performed by Pearson linear analysis and Bland-Altman analysis accordingly. The mean post-filter ionized calcium was 0.42 ± 0.12 mmol/L, and mean ionized calcium level of effluent fluid was 0.39 ± 0.11 mmol/L. The ionized calcium level of effluent fluid was significantly correlated with post-filter ionized calcium in all continuous renal replacement therapy patients. Bland-Altman analysis showed that the mean difference of ionized calcium between two sampling sites in all continuous renal replacement therapy patients was -0.02 mmol/L with 95% confidence interval ranging from -0.09 to 0.04 mmol/L. The significant correlations and agreements were also demonstrated in continuous veno-venous hemofiltration, continuous veno-venous hemodialysis, and continuous veno-venous hemodiafiltration modalities separately. The effluent ionized calcium could be a considerable substitute for post-filter ionized calcium to monitor the validity of regional citrate anticoagulation in continuous renal replacement therapy with less blood loss.