Continuous Venovenous Hemofiltration Versus Continuous Venovenuous Hemodialysis

A Comparison of the Efficacy of Continuous Venovenous Hemofiltration Versus Continuous Venovenous Hemodialysis for Renal Replacement Therapy in Acute Kidney Injury

Acute kidney injury is often treated with the use of continuous renal replacement therapy. Two commonly used treatments are continuous venvenous hemofiltration (CVVH)and continuous venovenous hemodialysis (CVVHD). CVVH uses convective clearance to remove toxins and solutes from the patients circulation, while CVVHD relies on diffusive clearance to remove these same toxins/solutes. This study will evaluate which of these two methods is more effective at clearing the body of waste/solutes. We hypothesize that renal replacement therapy by either modality (hemodialysis or hemofiltration; CVVHD or CVVH, respectively) using a modern membrane and higher blood flow rates will be associated with similar clearances of both small and middle molecular weight solutes. We further believe that continuous renal replacement therapy using CVVHD will be associated with decreased clotting events and longer hemofilter survival, as well as improved resource utilization (i.e. nursing time, alarms, etc.).

The NxStage system will be used for CVVH using the NxStage Cartridge Express dialyzer (polyethersulfone membrane). The blood flow rate will be set at 250 cc/min, and decreased at the discretion of the primary nephrologist's assessment of filter pressures and alarms. Replacement fluid will be delivered pre-filter for CVVH; the target effluent flow rate will be 35ml/kg/hr plus desired ultrafiltration (fluid removal). A maximum of 4.5 L/hr effluent will be prescribed to obese or hypercatabolic patients.

The NxStage system will be used for CVVH and CVVHD using the NxStage Cartridge Express dialyzer (polyethersulfone membrane). The blood flow rate will be set at 250 cc/min, and decreased at the discretion of the primary nephrologist's assessment of filter pressures and alarms. Replacement fluid dialysate will be infused countercurrent to blood flow the target effluent flow rate will be 35ml/kg/hr plus desired ultrafiltration (fluid removal). A maximum of 4.5 L/hr effluent will be prescribed to obese or hypercatabolic patients.

To compare the clearance of urea and creatinine by renal replacement therapy (RRT) using continuous venovenous hemofiltration versus continuous venovenous hemodialysis.

To compare the clearance cystatin C and inflammatory cytokines (IL-6 and IL-10) by RRT using continuous venovenous hemofiltration versus continuous venovenous hemodialysis.

Inclusion Criteria: Age 18 or older and able to sign consent (or surrogate). Must have been referred to the inpatient Nephrology consult service for evaluation of acute kidney injury (AKI). Expected survival of at least 48 hours. Exclusion Criteria: Hemoglobin < 8 g/dl Serum potassium ≥6.5 milliequivalents per liter (mEq/L) Weight > 120kg.

Tsujimoto Y, Miki S, Shimada H, Tsujimoto H, Yasuda H, Kataoka Y, Fujii T. Non-pharmacological interventions for preventing clotting of extracorporeal circuits during continuous renal replacement therapy. Cochrane Database Syst Rev. 2021 Sep 14;9(9):CD013330. doi: 10.1002/14651858.CD013330.pub2.