A Case of Refractory Hyperammonemia due to Pediatric Acute Liver Failure Treated With Two‐Site Blood Purification Devices Prior to Liver Transplantation

BACKGROUND: Liver transplantation remains the established treatment for pediatric acute liver failure (PALF). Continuous hemodiafiltration (CHDF) and plasma exchange (PE) are implemented as bridging therapies to liver regeneration or liver transplantation. We report a pediatric case in which conventional CHDF failed to optimize ammonia levels, yet management using two blood purification devices successfully rescued the patient without neurological sequelae. CASE PRESENTATION: The patient was a 6-year-old boy. Upon transfer, the patient exhibited drowsiness and disorientation. Laboratory tests showed AST 387 IU/L, ALT 579 IU/L, total bilirubin 8.9 mg/dL, ammonia levels 92 μg/dL, and PT-INR 2.6. EEG revealed generalized slowing. Encephalopathic PALF was diagnosed. On admission, ammonia was 92 μg/dL, which rapidly increased to 281 μg/dL prior to initiation of CHDF. Despite intensification of dialysis parameters and addition of pharmacotherapy, ammonia levels remained above 200 μg/dL until the following day. Therefore, an additional 11 Fr dialysis catheter was placed in the right femoral vein, and CHDF management was conducted using two blood purification devices. As a result, ammonia levels dropped below 150 μg/dL within approximately 5 h and were maintained thereafter (maximum settings: dialysate flow 16 000 mL/h, convective substitution volume 4000 mL/h). Electroencephalography (EEG) showed generalized slowing resolved, and consciousness gradually improved. After living donor liver transplantation (LDLT), the patient was extubated on postoperative day 1 and was fully conscious and clinically stable by postoperative day 9, at which point he was transferred to the general ward. CONCLUSION: Management using two-site blood purification devices was an effective method for controlling refractory hyperammonemia.