New experiences with the therapy of acute kidney injury.

Acute kidney injury (AKI) is encountered in a variety of settings (e.g., hospitalized and outpatient, non-intensive and intensive care unit patients, pediatric, adult, and elderly), with varied clinical manifestations ranging from a minimal elevation of serum creatinine (SCr) to anuric renal failure and/or multi organ failure (MOF), and a wide variation in causes, risk factors and comorbiditis. There is no hard and fast rule as to when renal replacement therapy (RRT) should be initiated, but is clearly not sensible to wait until an obvious uremic complication arises. Modern practice is to initiate RRT sooner rather than later, for example, when the SCr concentration reaches 500-700 micromol/L, perhaps even earlier, unless there is clear evidence that renal function is about to recover. The choice of the treatment will depend on the clinical practice, technical resources, and well-trained nurses of a given department, than on precise clinical indication. The ideal RRT should mimic the functions and physiological mechanisms of the native organ, ensuring qualitative and quantitative blood purification, be free of complications, have good clinical tolerance and restore and maintain homeostasis, thus favouring organ recovery. Now available RRT options /peritoneal dialysis (PD), 2. intermittent hemodialysis (IHD), 3. continuous therapies (CRRT), and 4. hybrid therapies/, differ in the method of delivery, efficiency, and their clinical tolerability. AKI without MOF is less complex, can be managed outside intensive care unit and the same RRT techniques used for the treatment of chronic renal failure may be applied. AKI associated with MOF is a more complex condition and requires more flexible RRT. Acute PD remains a viable option for the treatment of selected patients with AKI, particularly pediatric population, and those who are hemodynamically compromised, have severe coagulation abnormalities, difficulty in obtaining blood access, removal of high molecular weight toxins (> 10 kD), and clinically significant hypothermia and hyperthermia. Patients that are hemodynamically stable can be managed with IHD techniques. Maintaining hemodynamic stability is probably one of the most important aspects of dialysis technique as well as one of the most difficult challenges. With CRRT, the continuous regulation of volume homeostasis could lessen the hourly rate of required UF, thereby improving hemodynamic stability compared with IHD. Clinical data suggest that CRRT should be strongly considered for patients with severe hyperphosphatemia, elevated intracranial pressure, cerebral edema complicating acute liver failure, sepsis or septic shock, might be a useful component of therapy for lithium intoxication, and because of continuous nature of process prevents the post-dialytic "rebound" elevation of plasma concentration of uremic toxins typically seen with IHD. Hybrid therapies using a variety of machines are safe and convenient, providing excellent control of electrolytes and fluid balance, and offers several advantages over CRRT, including less cumbersome technique, patient mobility, and decreased requirements for anticoagulation, while providing similar hemodynamic stability and volume control. Currently, it has been found no difference in mortality or renal recovery between hybrid RRT, CRRT or IHD for critically ill patients with AKI. However, future investigations should collect detailed information on long-term costs and the relative likelihood of renal recovery associated with dialysis modality.