Myoglobin clearance by continuous venous-venous haemofiltration in rhabdomyolysis with acute kidney injury: a case series.

BACKGROUND Clearance of circulating myoglobin is a critical measure to prevent further damage in patients with rhabdomyolysis (RM) and acute kidney injury (AKI). Continuous venous-venous haemofiltration has emerged to be a novel approach for this purpose. The objective of present study is to evaluate the efficacy and safety of CVVH in myoglobin clearance for patients with RM complicated with AKI. METHOD We prospectively analysed 15 patients with acute RM and AKI due to crush syndrome (n=7), bee stings (n=5), polymyositis (n=2) and heroin poisoning (n=1). All of them presented oliguria with high serum myoglobin and creatine kinase concentration. They were treated by CVVH for at least 48h until the conditions turned to be stable, then replaced by intermittent renal replacement therapy (intermittent haemofiltration or haemodialysis). Meanwhile intravascular volume expansion, urinary alkalinisation, and forced diuresis were administered. During the procedure, serum and effluent concentrations of myoglobin and creatinine were measured simultaneously at 2, 6, 12 and 24h. RESULT The mean sieving coefficients for myoglobin were 0.28±0.06, 0.21±0.06, 0.15±0.02 and 0.11±0.02 during 2, 6, 12 and 24h of CVVH intervention, whilst mean clearance of myoglobin was 14.3±3.1ml/min during 2h and reduced to 11.5±3.2, 7.5±0.9, 5.6±1.0ml/min during 6, 12 and 24h. In contrast to myoglobin, the sieving coefficient for creatinine remained stable at 0.95±0.25, 1.02±0.12, 0.89±0.32, 0.98±0.27 during 24h of CVVH. In all of the 15 patients, serum myoglobin and creatine kinase were dramatically decreased in 24h (-56.2 and -32.1%), 3 days (-72.9 and -50.3%) and in 7 days (-97.6 and -96.7%). Seven patients (46.7%) complicated with hypophosphatemia during CVVH intervention improved in natural course after the cessation of CVVH. After 16±12 days, all of 15 patients came to polyuria stage and finally, discharged with normal renal function after 31±15 days. CONCLUSION Our study showed CVVH can be employed to clear myoglobin effectively in patients with RM and AKI and presented oliguria. This indicate that CVVH would be better than other modes of renal replement treatment in acute RM with AKI because of the additional benefit of myoglobin removal, but large sample randomised controlled trials are still required to confirm it.