A comparison of metabolic control by continuous and intermittent therapies in acute renal failure

Abstract

Azotemia control provided by blood pump-assisted continuous hemofiltration has not been rigorously compared with that provided by intermittent hemo-dialysis (IHD) for critically ill patients with acute renal failure (ARF). The metabolic control achieved by continuous venovenous hemofiltration (CVVH) and IHD was compared. In ARF patients treated with CVVH (N= 11), the normalized daily dose of therapy was 0.59 ± 0.23 (mean ± SD) and the normalized protein catabolic rate was 1.82 ± 0.95 g/kg per day. The serum urea nitrogen concentration (SUN) declined with CVVH from an initial value of 114 ± 32 to 79 ± 17 mg/dL at steady state (SUNS). The initial analysis was a theoretical comparison between CVVH azotemia control and the control that would have been provided by IHD. Simulated IHD data were generated by conventional urea kinetic methods. The peak concentration hypothesis was invoked to compare CVVH SUNs and the peak IHD SUN (SUNP). A simulated IHD frequency of five times or more weekly was required to achieve a SUNP that did not differ from the CVVH SUNs. A similar comparison between the CVVH group and a separate group of ARF patients (N = 11) who received IHD was also performed. In the latter group, the normalized protein catabolic rate and the normalized daily dose of therapy were similar to those of the CVVH group. The SUNP (101 ± 12 mg/dL) in the IHD group was significantly higher than the mean CVVH SUNs (P<0.05). These data suggest that intensive hemodialysis is required to provide azotemia control similar to that provided by CVVH. In addition, for equivalent amounts of therapy, CVVH achieves better azotemia control than IHD.