CREATININE AND UREA CLEARANCE DURING CONTINUOUS VENOVENOUS HEMOFILTRATION IN CRITICALLY ILL PATIENTS

Urea and creatinine clearances achieved using continuous veno-venous h aemofiltration were calculated in 16 critically ill patients, during 5 0 episodes of filtration. The effects of filter life and the volume of ultrafiltrate on these clearances were also evaluated. Clearances wer e calculated from urea and creatinine concentrations in blood and ultr afiltrate and the volume of ultrafiltrate produced. The overall mean ( SD) urea clearance was 26.6 (6.0) ml.min(-1) and the overall creatine clearance was 30.1 (6.3) ml.min(-1). The mean (SD) ultrafiltrate produ ction was 29.6 (5.9) ml.min(-1). Creatinine clearance was significantl y lower in filters that failed within 24 h (filters < 24 h 27.5 (6.3) ml.min(-1); filters > 24 h 32.2 (5.5) ml.min(-1)). The clearance of bo th solutes increased with increasing ultrafiltrate volume (p < 0.001). We conclude that satisfactory clearance of urea and creatinine can be achieved using continuous veno-venous haemofiltration. Increases in u ltrafiltrate production lead to similar increases in urea and creatini ne clearance. Prolongation of filter life may improve creatinine clear ance.