A randomized controlled trial comparing intermittent with continuous dialysis in patients with ARF.

BACKGROUND: Despite the widespread use of continuous renal replacement therapy in critically ill patients with acute renal failure (ARF), there are few data supporting its benefits over conventional intermittent hemodialysis (IHD). We sought to analyze differences in survival between modalities in a study that compared continuous venovenous hemodialysis (CVVHD) with IHD. METHODS: Eighty critically ill patients with ARF requiring dialysis were randomized after stratification by severity of illness to treatment with CVVHD or IHD. RESULTS: There were no differences in survival or renal recovery between groups. In patients who died, mean survival time was 10.7 +/- 11.2 days for the IHD group versus 14.3 +/- 16.1 days for the CVVHD group (P = not significant). There was greater net volume removal in the CVVHD group during 72 hours. Declines in urine output during 72 hours were similar between groups. Mean arterial pressure off and on dialysis therapy was analyzed retrospectively. There was a significant decrease in mean arterial pressure for patients on IHD therapy not seen in those on CVVHD therapy, but this did not lead to a survival advantage. CONCLUSION: Despite greater volume control, CVVHD did not lead to an improvement in survival, preservation of urine output, or renal recovery compared with IHD in patients with ARF.

Dialyzer fiber bundle volume and kinetics of solute removal in continuous venovenous hemodialysis.

The relationship between dialyzer fiber bundle volume (FBV), dialyzer life span, and small-solute clearance has yet to be clearly defined in continuous venovenous hemodialysis (CVVHD). This study sought to define this relationship using novel ultrasound dilution technology. We studied 55 sessions in 31 intensive care unit patients on CVVHD therapy. A session was defined as the life span of a single dialyzer. The following variables were assessed every 6 hours throughout each session, starting within 1 hour of initiation of that session: FBV, access recirculation, extracorporeal blood flow rate, effluent (EUN) to blood urea nitrogen (BUN) concentration ratio, effluent creatinine to blood creatinine concentration ratio, and urea nitrogen and creatinine clearances. Data were analyzed using random-effects linear models to estimate trends. Several dialysis-related and solute-removal parameters were analyzed for association with each other. Systemic or dialysis circuit heparin was administered in 28 of 55 sessions. One hundred seventy sets of FBV, 101 sets of urea clearance, and 102 sets of creatinine clearance measurements were performed. There was a declining trend for FBV (0.8 mL/h), heart rate (0.25 beats/min/h), and measured blood flow (0.33 mL/min/h; P < 0.05). Apart from dialysate inflow rate (P = 0.044), there was no significant correlation with EUN-BUN ratio. Session duration was associated with dialysis access site; the femoral access provided longer dialysis sessions than subclavian and internal jugular accesses (P = 0.029). We conclude that small-solute removal remains stable over the course of our CVVHD system life spans despite significant loss of hemodialyzer FBV.