Biochemical effects of phosphate-containing replacement fluid for continuous venovenous hemofiltration

Aims: To examine biochemical effects of phosphate-containing replacement fluid (Phoxilium?) for continuous venovenous hemofiltration (CVVH). Methods: Retrospective comparison of respective serum biochemistry with sequential use of Accusol? and Phoxilium, each over 48 h of CVVH. Results: We studied 15 critically ill patients. Accusol was switched to Phoxilium after 5 (4-8) days of CVVH. Respective serum biochemistry after 36-42 h of Accusol versus Phoxilium were: phosphate 1.02 (0.82-1.15) versus 1.44 (1.23-1.78) mmol/l, ionized calcium 1.28 (1.22-1.32) versus 1.12 (1.06-1.21) mmol/l, bicarbonate 24 (23-25) versus 20 (19-22) mmol/l, base excess 0 (-2 to 1) versus -4 (-6 to -3) mmol/l (p <0.001). Cumulative phosphate intakes during respective periods were 69.6 (56.6-76.6) versus 67.2 (46.6-79.0) mmol (p = 0.45). Plasma strong ion differences were narrower with Phoxilium (p <0.05), with similar strong ion gaps. No additional intravenous phosphate was given during Phoxilium use. Seven patients had serum phosphate >1.44 mmol/l. Conclusions: Phoxilium versus Accusol use during CVVH effectively prevented hypophosphatemia but contributed to mild hyperphosphatemia, and is associated with relative hypocalcemia and metabolic acidosis.