A 14-year-old male developed multisystem inflammatory syndrome in children (MIS-C) after acquiring the SARS-CoV-2 infection. He deteriorated rapidly requiring inotropic and ventilatory support as well as continuous renal replacement therapy (CRRT) due to rhabdomyolysis-associated acute kidney injury. A hemoadsoprtion column Cytosorb® was first incorporated into the CRRT circuit for myoglobin and cytokines removal, which was followed by sequential use of another type of cytokine-removing hemofilter (Oxiris®) (altogether 100 hours of extracorporeal blood purification [EBP] therapy). There was no major complication related to the EBP therapy. Cytokine profile revealed a marked reduction of levels of several cytokines including tumor necrosis factor-α, interleukin (IL)-6, IL-8, and IL-10 after the EBP therapy. It was noted that both pro-inflammatory and anti-inflammatory cytokines were removed, and the removal efficacy varied between different devices. His condition improved and the serum ferritin, C-reactive protein, and procalcitonin levels also dropped gradually, which correlated well with his clinical progress and the trend of cytokine levels. Our case demonstrated that extracorporeal cytokine removal can be safely applied in children with MIS-C and can be considered as adjunctive therapy in selected patients with critically ill conditions.

Extracorporeal blood purification (EBP) is increasingly applied for bilirubin removal in critical care setting. We retrospectively reviewed the clinical features of children aged 1 month to 18 years old who received EBP for hyperbilirubinemia and explored the bilirubin removal kinetics by hemoadsorption (HA) in the pediatric intensive care unit of Hong Kong Children’s Hospital from 3/2019 to 7/2022. Among the 14 episodes of EBP from six patients with a median age (interquartile range [IQR]) of 9.3(5.5) years old, 57.1% of them received HA, 33.3% received single-pass albumin dialysis (SPAD), and 7.1% received combined SPAD and HA. All HA episodes employed the Cytosorb® column. The median (IQR) pre-HA peak total bilirubin level was 406 (254) μmol/L. The saturation duration per HA episode was significantly shorter than the corresponding total treatment duration (8 vs 24 h, p = 0.012), and the median total and effective HA doses were 9.8(6.8) L/kg and 300.0 (163.4) mL/kg/h respectively. The overall bilirubin removal ratio by HA was 44.6 (14.5)%. A higher HA effective dose and a higher pre-HA bilirubin level were both associated with better bilirubin removal. No major EBP-specific complication was encountered. The liver enzymes showed improvement in all children. No patients required liver transplantation. There was no EBP-related mortality, but the overall PICU mortality of the cohort was 50%. HA was a safe and effective modality for bilirubin removal among children. Future studies should investigate the impact of bilirubin removal on clinical outcomes and explore the factors responsible for better removal efficacy.