Feasibility of strategies to manage dysnatremia in pediatric CKRT: a simulation study

Correction of dysnatremia during continuous kidney replacement therapy (CKRT) presents unique technical challenges. Most published experience comes from isolated case series, with limited comparative data across patient sizes or sodium ranges. Although several approaches (bag adjustment, post-filter substitution, and continuous infusion) have been described, their feasibility in pediatric practice has not been systematically evaluated.

A Python-based computational model of pediatric CKRT was developed to simulate all feasible allocations of dialysate, replacement, and infusion flows achieving a target 6 mmol/L sodium correction across a range of body weights (5-80 kg). Three sodium-management strategies were assessed: (1) Bag adjustment, (2) post-filter bag change, and (3) continuous infusion. Feasibility required outlet sodium accuracy within ±0.5 mmol/L, clearance within ±10%, filtration fraction < 20%, and post-filter flow ≥ 100 mL/h. Liberalized criteria were subsequently explored.

A total of 33,074 (n = 17,269 citrate-free) simulations were completed. Bag adjustment and continuous infusion were feasible across all patient sizes and sodium ranges. In contrast, post-filter bag change frequently failed in patients ≤ 20 kg and at higher sodium targets (≥ 120 mmol/L for hyponatremia, ≥ 161 mmol/L for hypernatremia) due to the inability to maintain the minimum post-filter flow standard in pediatric practice. Liberalizing other parameters had minimal effect; only the removal of the post-filter flow minimum restored full feasibility.

Bag adjustment and continuous infusion methods are universally feasible for pediatric CKRT sodium correction, whereas post-filter substitution is limited by mechanical constraints in small circuits. Computational modeling and the accompanying open-access tool ( https://crrt-sodium.netlify.app ) provide a framework for individualized dysnatremia management in CKRT.