Continuous renal replacement therapy and the failing kidneys

The failing kidneys of critically ill patients and their ability to recover are profoundly influenced by the kind of renal replacement therapy provided. Much evidence suggests that intermittent hemodialysis and the hemodynamic changes associated with it are injurious to the failing (and recovering) kidneys, whereas this is not the case for continuous renal replacement therapy (CRRT). In addition, the use of CRRT allows the physician to intervene much earlier in the course of renal failure and thereby prevent major physiological derangements from taking place. Such derangements are likely to adversely affect renal recovery. The ability to safely prevent, rather than merely treat, derangements of homeostasis has redefined the criteria for initiating dialytic therapy in the intensive care unit. Furthermore, the superiority of CRRT can be demonstrated at all levels of physiological control, confirming that adequacy of dialysis can be approximated by CRRT but not by intermittent hemodialysis. Finally, CRRT circuits can be modified and technology altered to increase the depth of blood purification. New developments in this area directed at a broad anti-inflammatory effect as well as the provision of CRRT show promise and are being tested in pilot human studies.