Dialyzer clearance of myoglobin with middle molecule filter and low blood flow CVVHD in patients with rhabdomyolysis-associated acute kidney injury

Abstract

Introduction Rhabdomyolysis-associated acute kidney injury can be treated with various modes of renal replacement therapy (RRT) [1,2]. We have used continuous venoveno hemodialysis (CVVHD) with middle molecule f lter and low extracorporeal blood flow (100 to 180 ml/minute) to avoid albumin loss and hemodynamic instability. Methods We treated nine patients suf ering from rhabdomyolysis and acute kidney injury with various causes. We used a CVVHD mode with low (100 to 180 ml/minute) blood flow and a middle molecule f lter (Ultraf ux EMiC2; 1.8 m 2 surface area, polysulfone membrane, cutof at 40 kDa, blood f lling volume 130 ml, blood flow range 100 to 350 ml/minute, maximum dialysate flow 1,000 ml/minute). Myoglobin and albumin concentrations were measured from prefilter and postf lter samples and dialyzer clearances were calculated (CLdial = blood flowxCpre -Cpost/Cpre + UFxCpre/Cpost). Measurements were taken at 0, 15 minutes, 30 minutes, 4 hours, 12 hours, 24 hours, 36 hours and 48 hours from the start of the CRRT or until CRRT was no longer needed. Results The baseline and prefilter plasma albumin concentrations varied from 8 to 29 g/l. Postf lter and post-treatment albumin concentrations remained comparable. Prefilter concentrations of myoglobin (17.8 kDa) varied from 96,109 to 747 mug/l and the dialyzer clearance of myoglobin from 50.6 to 0 ml/minute. The mean dialyzer clearance was 23.1 ml/minute and the median clearance 22.2 ml/minute. Maximal changes between corresponding prefilter and postf lter samples were: absolute concentration change 27,091 mug/l, percentage 34%, dialyzer clearance 50.6 ml/minute. Clearances were achieved with low extracorporeal blood flow between 100 and 180 ml/minute, most commonly 120 ml/minute. Ultrafiltration (UF) was used only at f ve of the 56 time points calculated, because of hemodynamic instability. All patients required either vasopressor or vasopressor and inotrope support. The highest dialyzer clearance of myoglobin (50.6 ml/minute) was measured at the prefilter myoglobin of 29,266 mug/l, blood flow 180 ml/ml and no UF. Conclusion In a rhabdomyolysis-associated kidney injury a middle molecule f lter and a low blood flow CVVHD of er a safe and effective treatment choice for patients requiring vasopressor or vasopressor and inotrope for hemodynamic support.