Continuous veno-venous hemodiafiltration or hemofiltration: Impact on calcium, phosphate and magnesium concentrations

Background and Objectives: Different techniques of continuous renal replacement therapy (CRRT) might have different effects on calcium, phosphate and magnesium concentrations. Accordingly, we tested whether continuous veno-venous hemodiafiltration (CVVHDF) or continuous venovenous hemofiltration (CVVH) would achieve better control of these electrolytes. Design: Retrospective controlled study Setting: Two tertiary Intensive Care Units Patients: Critically ill patients with acute renal failure (ARF) treated with CVVHDF (n=49) or CVVH (n=50) Interventions: Retrieval of daily morning ionized calcium, phosphate and magnesium before and after the initiation of CRRT for up to 2 weeks of treatment. Measurements and Results: Before treatment, both groups had a high incidence of abnormal ionized calcium concentrations (57.2% for CVVHDF vs 46.0% for CVVH; NS). After treatment, both groups showed a significant increase in serum calcium concentration over the first 48 h (p=0.041 vs p=0.0048) but hypercalcemia was more common during CVVHDF (15.3% vs 0.4%; p<0.0001). However, in both groups, hypocalcemia remained common (30.9% vs 36.7%; NS). Before treatment, abnormal serum phosphate concentrations were also common (65.1% for CVVHDF vs 78.1% for CVVH; NS). After treatment, both groups achieved a significant reduction of serum phosphate within 48 hours (p