New perspectives in the treatment of acute renal failure.

The evolution of technology and biomaterials has permitted a parallel development of renal replacement therapies in the acute, critically ill patient. From the original description of continuous arterio-venous haemofiltration, new techniques such as continuous veno-venous haemofiltration, haemodiafiltration and high flux dialysis have been developed and clinically utilised. A parallel improvement in efficiency has been achieved with urea daily clearances as high as 50 litres or more. The use of special highly permeable dialysers has also permitted to increase the clearances of larger solutes thus leading to significant removals of chemical substances involved in the acute inflammation and sepsis. In this field, recent observations have suggested to use haemofiltration with high volumes of fluid exchange. The hardware and software of the newer continuous renal replacement therapies (CRRT) are certainly the key point in achieving these results and in safely performing such challenging techniques.