Updated Management of Sodium Disorders During Continuous Venovenous Hemofiltration

Severe hyponatremia or hypernatremia in critically ill patients requiring continuous venovenous hemofiltration (CVVH) presents a therapeutic challenge. Adjusting replacement-fluid sodium concentrations may help control correction and reduce the risk of neurologic complications. This practical narrative review summarizes approaches to customizing standard 5-L CVVH replacement-fluid bags, drawing on physiologic principles, published case reports, small case series, and protocol-based experiences. Calculations, correction targets, compounding precautions, and biochemical monitoring are described. For hypernatremia, calculated volumes of 3% NaCl can replace equal volumes of baseline fluid to increase sodium concentration while maintaining a final bag volume of 5.0 L. For hyponatremia, sterile-water dilution lowers replacement-fluid sodium but also reduces all other solute concentrations, requiring product-specific calculations and co-electrolyte monitoring. In chronic hyponatremia, correction is generally limited to ≤ 8 mmol/L per 24 h, with a more conservative 4-6 mmol/L target in patients at very high risk for osmotic demyelination. Individualized prescriptions should account for final fluid volume, effluent dose, and concurrent sodium and water inputs. Serum sodium should initially be measured every 4-6 h. Customized CVVH replacement fluid provides a practical approach to gradual sodium correction when implemented through a validated local compounding protocol with pharmacy or ICU oversight and frequent biochemical monitoring. Evidence remains largely case-based and protocol-derived, and comparative efficacy and safety are not established.