High Cut-Off Renal Replacement Therapy for Removal of Myoglobin in Severe Rhabdomyolysis and Acute Kidney Injury: A Case Series

<b><i>Background/Aim:</i></b> Rhabdomyolysis is associated with the release of myoglobin into the circulation, promoting acute kidney injury (AKI). In severe rhabdomyolysis, dialysis-dependent AKI doubles mortality. Standard blood purification techniques have limited efficacy in removing myoglobin. We describe high cut-off (HCO) renal replacement therapy (RRT) as a novel approach for extracorporeal elimination of myoglobin in rhabdomyolysis-associated AKI. <b><i>Methods:</i></b> With an in vivo molecular cut-off at 45 kDa, HCO filters are effective in removing myoglobin (17.8 kDa). Clearances across standard and HCO filters using continuous or intermittent RRT are reviewed in a case series of 11 patients with severe rhabdomyolysis and dialysis-dependent AKI. <b><i>Results:</i></b> Median myoglobin clearance across standard high-flux filters was 3.3 (interquartile range 2.3–3.9) ml/min for sustained low-efficiency daily dialysis (SLEDD) batch hemodialysis (HD) and 3.7 (2.9–6.7) ml/min for conventional HD. Respective clearances using HCO filters (membrane surface area: 1.1 m²) were 21.7 (20.3–26.1) ml/min (SLEDD) and 44.2 (41.3–47.0) ml/min (HD). Corrected for filter size, up to 20-fold higher clearances were obtained using HCO filters, resulting in profound and sustained reduction of plasma myoglobin concentration. <b><i>Conclusions:</i></b> As a novel approach, HCO RRT allows for rapid and effective removal of myoglobin from the circulation. In light of the pathogenic role in AKI, reducing exposure of the kidney to myoglobin may improve renal recovery and patient outcome. Our data pave the way for prospective trials, addressing this issue.