Continuous veno-venous hemodiafiltration for the treatment of spontaneous tumor lysis syndrome complicated by acute renal failure and severe hyperuricemia.

We describe a case of Burkitt's lymphoma presenting as spontaneous tumor lysis syndrome (TLS) complicated by severe hyperuricemia and anuric acute renal failure presumed to be secondary to uric acid nephropathy. The patient was treated with continuous veno-venous hemodiafiltration (CVVHDF) using a dialysate flow rate of 2.5 l/h, and a replacement fluid rate of 1.5 l/h (administered in pre-dilution). Mean clearances during CVVHDF for urea, creatinine, uric acid, and phosphorus were, respectively, 55.8 +/- 3.8, 48.9 +/- 2.6, 45.1 +/- 2.6 and 47.0 +/- 3.3 ml/min (or 80, 70, 65 and 68 l/day, respectively). Serum urea, creatinine, uric acid, and phosphorus decreased from 42 to 9 mmol/l, 533 to 189 micromol/l, 1980 to 372 micromol/l, and 2.0 to 1.4 mmol/l, respectively, after 48 hours of CVVHDF. Previously, we reported the use of continuous arteriovenous hemodialysis (CAVHD) at a high dialysate flow rate of 4 l/h for the treatment of acute renal failure and TLS, which provided excellent continuous clearances of small molecular weight solutes. This last modality was very efficient and prevented deleterious rebound in serum solute concentrations frequently observed in TLS after intermittent hemodialysis (IHD). It was concluded that high-dialysate flow rate CAVHD was a more potent form of treatment than conventional IHD. With recent advances in technology, veno-venous continuous renal replacement therapies are becoming more popular than arterio-venous modalities since they are safer and less cumbersome. Furthermore, flow rates being precisely regulated, solute clearances can be steadily maintained. With CVVHDF flow rates as used in this report, we achieved excellent solute clearances and metabolic control. We propose CVVHDF as an ideal treatment for acute renal failure in TLS. In our opinion, CVVHDF is an advantageous alternative to treat TLS complicated by acute renal failure.

Myoglobin clearance and removal during continuous venovenous hemofiltration.

Myoglobin has a relatively high molecular weight of 17,000 Da and is poorly cleared by dialysis (diffusion). However, elimination of myoglobin might be enhanced by an epuration modality based on convection for solute clearances. We present a single case of myoglobin-induced renal failure (peak creatine kinase level: 313,500 IU/l) treated by continuous venovenous hemofiltration (CVVH). Our purpose was to evaluate the efficiency of such a modality using an ultrafiltration rate of 2 to 3 l/h for myoglobin removal and clearance. The hemofilter was a 0.9 m(2) polyacrylonitrile (AN69) membrane Multiflow-100 (Hospal-Gambro, St-Leonard, Canada) and the blood flow rate was maintained at 150 ml/min by an AK-10 pump (Hospal-Gambro, St-Leonard, Canada). The ultrafiltration bag was placed 60 cm below the hemofilter and was free of pump control or suction device. Serum myoglobin concentration was 92,000 microg/l at CVVH initiation and dropped to 28,600 microg/l after 18 h of the continuous modality. The mean sieving coefficient for myoglobin was 0.6 during the first 9 h of therapy and this decreased to 0.4 during the following 7 h. Mean clearance of myoglobin was 22 ml/min, decreasing to 14 ml/min during corresponding periods, while the mean ultrafiltration rates were relatively stable at 2,153 +/- 148 ml/h and 2,074 +/- 85 ml/h, respectively. In contrast to myoglobin, the sieving coefficeint for urea, creatinine, and phosphorus remained stable at 1.0 during the first 16 h of CVVH. More than 700 mg of myoglobin were removed by CVVH during the entire treatment. In conclusion, considerable amounts of myoglobin can be removed by an extracorporeal modality allowing important convective fluxes and middle molecule clearances, such as CVVH at a rate of 2 to 3 l/h using an AN69 hemofilter. If myoglobin clearance had been maintained at 22 ml/min, 32 l of serum would have been cleared per day. However, the sieving coefficient of myoglobin decreased over time, probably as a consequence of protein coating and/or blood clotting of the hemofilter. Whereas myoglobin can be removed by CVVH, it remains unknown at this point if such a modality, applied early, can alter or shorten the course of myoglobinuric acute renal failure.

Serum concentrations and clearances of folic acid and pyridoxal-5-phosphate during venovenous continuous renal replacement therapy.

OBJECTIVE: To determine to what extent hydrosoluble vitamins are removed by continuous renal replacement therapy (CRRT); to evaluate clearances, removal rates, and evolution of serum concentrations of folic acid and pyridoxal-5'-phosphate (P-5'-P), the active moiety of vitamin B6 during CRRT. DESIGN: A prospective, non-interventional, descriptive study on vitamin losses induced by CRRT. SETTING: Medical and surgical intensive care units in a tertiary university-affiliated hospital. PATIENTS: A total of ten critically ill patients in oligoanuric acute renal failure (five treated by continuous venovenous hemofiltration and five by continuous venovenous hemodiafiltration) with a mean effluent rate of 1801 +/- 468 ml/h. Nutritional support was not modified and additional vitamin supplements were not provided during study periods. MEASUREMENTS AND RESULTS: Concentrations of folic acid and P-5'-P were determined daily during CRRT. Samples for folic acid, P-5'-P, urea, and creatinine were taken simultaneously from the blood at the dialyzer inlet and from the effluent, at CRRT initiation, and daily thereafter over an average of 3.4 +/- 1.2 days. Samples were processed by immunochemiluminescence for folic acid and by radioenzymatic assay for P-5'-P determinations with normal ranges above 6.8 nmol/l and from 11.5 to 179.3 nmol/l, respectively. Marked decreases in serum folic acid and P-5'-P concentrations were noticed over time with mean daily reductions of 12.6 and 13.7%. Serum folic acid concentrations decreased from 42.7 to 16.0 nmol/l and serum P-5'-P decreased from 14.4 to 5.0 nmol/l in the blood coming in to the dialyzer over the study period. Clearances and removal rates were determined from the effluent side. During CRRT, mean (+/- SEM) folic acid and P-5'-P clearances were 20.5 +/- 6.3 ml/min (n = 34) and 13.2 +/- 10.6 ml/min (n = 22), whereas mean urea clearance was 27.1 +/- 5.1 ml/min (n = 26). Folic acid and P-5'-P removal rates were 27.0 +/- 34.2 and 3.4 +/- 2.0 nmol/h, corresponding to mean daily losses of nearly 650 and 80 nmol/day respectively. CONCLUSION: Significant losses of folic acid and P-5'-P (and most likely of other hydrosoluble vitamins) occur during CRRT. Considering that stores of most hydrosoluble vitamins are relatively low in critically ill patients, supplementation should be provided to patients treated similarly.