Continuous renal replacement therapy: evolution in technology and current nomenclature.

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 arteriovenous hemofiltration (CAVH), new techniques such as continuous venous venous hemofiltration (CVVH), hemodiafiltration (HDF) and high flux dialysis (HFD) have been developed and clinically utilized. A parallel improvement in efficiency has been achieved with daily clearances of urea as high as 50 liters or more. The use of special highly permeable dialyzers has also permitted increases in the clearances of larger solutes, thus leading to significant removals of chemical substances involved the acute inflammation and sepsis. In this field, recent observations have suggested the use of hemofiltration with high volumes of fluid exchange. The hardware and software of the newer continuous renal replacement therapy (CRRT) systems are certainly the key points in achieving these results and in safely performing such challenging techniques.