Hemofilters versus hemodialyzers: impacts on cytokine removal during cardiopulmonary bypass in pediatric cardiac surgery: a randomized controlled trial

BACKGROUND: Congenital heart disease (CHD) remains a leading cause of pediatric morbidity and mortality worldwide. Cardiopulmonary bypass (CPB) is crucial for surgical repair but is associated with systemic inflammation and/or end-organ dysfunction. Ultrafiltration (UF) techniques, particularly zero-balance ultrafiltration (Z-BUF), have been developed to mitigate these effects by removing cytokines. Conventional hemofilters are widely used, but in low- and middle-income countries, high-flux hemodialyzers are increasingly substituted, although evidence for their equivalence in pediatric CPB remains scarce. METHODS: hemodialyzer group. Interleukin-6 (IL-6) was designated as the primary endpoint, whereas interleukin-1β (IL-1β), hematocrit, lactate levels, mechanical ventilation (MV) duration, length of stay in the intensive care unit (ICU), and overall hospital stay served as secondary endpoints. Cytokine levels were measured at baseline (T1), before Z-BUF (T2), and immediately after Z-BUF (T3). Prespecified noninferiority margins were applied, and generalized estimating equations (GEEs) were used to assess temporal trends. RESULTS: Baseline characteristics and procedural complexity were comparable between cohorts. Following Z-BUF, changes in IL-1β (median difference - 0.223 pg/mL) and IL-6 (0.642 pg/mL) met the predefined noninferiority criteria (p < 0.001 for both). GEE analysis revealed no significant interaction between filter type and cytokine trends. The median hematocrit, lactate levels, MV duration, length of stay in the ICU, and overall hospital stay were also similar between the study arms. Mortality was identical (3.3%) in both arms. Importantly, no cases of acute kidney injury or acute neurological events were observed in either group. CONCLUSIONS: Compared with conventional hemofilters, high-flux hemodialyzers are noninferior in controlling intraoperative cytokines during Z-BUF in pediatric CPB and demonstrate comparable clinical safety outcomes. Hemodialyzers appear to be an effective and practical alternative in resource-limited settings. Validation in larger multicenter trials with extended postoperative sampling is warranted. TRIAL REGISTRATION AND DATE: ClinicalTrials.gov (NCT06792565) on 22 March 2024.