CRRT Protects the Kidney during Acute Renal Failure

© Wichtig Editore, 2007 0391-3988/279-02 $15.00/0 Acute kidney injury is an important syndrome that may affect a significant number of patients admitted to the intensive care unit. Prevention of acute kidney injury includes many pharmacological as well as physiological measures designed to reduce the level of injury, to eliminate or mitigate the presence of toxic agents, and finally to protect the kidney from hypoperfusion and ischemia. All these measures are generally implemented at a very early stage, although there is a certain consensus that in most cases we are not intervening early enough and the preventive measures are generally put in place when some damage has already occurred. The debate should, however, proceed by discussing another issue, i.e. the role of kidney protection when the acute renal failure is already clinically manifest. There is a certain tendency to neglect the kidney once it is failing, based on the misconception that further insults to the organ cannot make the syndrome worse once it has been established. On the other hand, there is a common belief that acute kidney injury should run its course and we cannot do anything to accelerate or affect renal recovery. Finally, there is a general impression that we have little or no impact on subsequent dialysis dependency. These concepts are all challenged by emerging evidence and to accept them passively without modifying our practice appears unacceptable today. Recent papers from the BEST (Beginning and Ending Supportive Therapy) Kidney consortium have demonstrated that dialysis dependency can be significantly lower in survivor patients if they were treated with continuous renal replacement therapy (CRRT) (1). This was also reported in previous papers by Mehta et al (2), although no difference in mortality among dialysis modalities was seen. Better renal recovery was confirmed recently in a paper on intensive care medicine by Max Bell and the SWING (Swedish Intensive Care Nephrology Group) (3). In a paper published in this issue of the International Journal of Artificial Organs by Shigehiko Uchino et al the concept is further underlined (4). Renal recovery is an important measure of outcome in acute renal failure and thus it becomes quintessential to ascertain if the renal replacement modality has any impact on this outcome measure. CRRT seems to provide less dialysis dependency compared to intermittent dialysis and a pathophysiological explanation for this observation can be easily found. In a previous paper, the BEST group showed a significantly higher incidence of hypotension in patients receiving intermittent hemodialysis (twice as much compared to CRRT) (1). The capacity of maintaining fluid balance (avoid too much in and avoid too much out too quickly), maintaining electrolyte homeostasis, correcting uremia and maintaining metabolic homeostasis is clearly recognized in CRRT (1). Thus, it seems that CRRT is somehow capable of protecting the kidney while it is failing for various reasons. Organ protection is about achieving homeostasis. Not doing so has a price. There might not be a detectable effect on mortality but there is a clear effect on recovery of the native organ and this results in a higher level of health and rehabilitation in the subsequent periods of the patient’s life. The gentle but effective correction of derangements and the maintenance of a steady correction of homeostasis by CRRT may influence the process of recovery of the kidney during and after the acute injury has occurred. Thus we must give the kidney a chance and offer the best possible environment for its recovery and regeneration. In conclusion, we should not forget to protect the kidney, even during the anuric phase of acute renal failure. We can still protect and preserve the renal parenchyma and its function from further injury by making efforts to achieve and maintain homeostasis. CRRT can be an important tool to achieve this goal.