A comparison of phosphate-containing versus conventional hemodialysis solutions for citrate-anticoagulated continuous veno-venous hemodialysis in patients with acute kidney injury.

Introduction Acute kidney injury (AKI) frequently necessitates continuous renal replacement therapy, often causing phosphate and magnesium losses. We evaluated whether a phosphate containing, magnesium-enriched dialysate reduces hypophosphatemia and hypomagnesemia compared to phosphate-free dialysate with standard magnesium concentration during citrate-anticoagulated continuous veno-venous hemodialysis (RCA-CVVHD) in ICU patients. Methods Single-center observational study comparing two adult ICU cohorts undergoing RCA-CVVHD from 2011-2014. The 2011-2012 cohort received phosphate-free dialysate with standard magnesium concentration (0.75 mmol/L) and intravenous phosphate and magnesium supplementation. The 2013-2014 cohort received a phosphate-containing (1.25 mmol/L), magnesium-enriched (1.0 mmol/L) dialysate. The primary endpoint was the incidence of hypophosphatemia and severe hypophosphatemia within 72 hours. Secondary outcomes included magnesium and calcium disturbances, delivered dialysis dose, solute control, filter lifespan, and clinical outcomes. Results We analyzed 85 patients in the 2011-2012 and 97 in the 2013-2014 cohort. Hypophosphatemia (92% vs. 68%, p < 0.001) and severe hypophosphatemia (65% vs. 28%, p < 0.001) were less frequent with phosphate-containing dialysate. Phosphate and magnesium levels were higher (p<0.008) with the phosphate-containing, magnesium-enriched solution. Fewer patients required phosphate (23% vs. 81%, p < 0.001) or magnesium (35% vs. 76%, p < 0.001) infusions. Ionized calcium and total calcium remained within target range in both cohorts. The delivered dialysis dose was 31.0±8.1 mL/kg/h in the 2011-2012 and 28.6±6.6 mL/kg/h in the 2013-2014 cohort (p = 0.025). More filters reached the maximum lifespan of 72 hours in the 2013-2014 cohort (64% vs. 75%; p = 0.03). Solute clearance and acid-base control were similar. Conclusion In ICU patients undergoing RCA-CVVHD, a phosphate-containing, magnesium-enriched dialysate was associated with significantly lower incidence and severity of hypophosphatemia, higher phosphate and magnesium levels, and lower need for separate electrolyte infusions. This phosphate-containing solution may offer relevant benefits, including reduced workload and potentially increased patient safety. These findings require confirmation in a RCT that includes relevant clinical endpoints.