Renal recovery after severe acute renal injury.

BACKGROUND: Recovery of renal function after acute renal injury is an important clinical determinant of patient morbidity and mortality. However, studies covering this field are scarce and nonhomogeneous.
FINDINGS: Despite success in animal models, translation of current pharmacologic strategies to limit the extent of kidney dysfunction or to hasten renal recovery from acute kidney injury (AKI) in human studies has failed. Renal replacement therapy is the mainstay of supportive care in patients with AKI. However, its performance can have untoward effects that contribute to the prolongation of the course of AKI or impede the ultimate recovery of complete renal function. Use of biocompatible membranes, daily hemodialysis, advanced intermittent hemodialysis (IHD) technology or continuous RRT (CRRT) have been coupled with shortened renal recovery after AKI. Rate of renal recovery to RRT independence is variable when judged at hospital discharge. The frequency of end-stage renal disease in survivors from AKI is highest in severe acute parenchymal renal disease and lowest in acute tubular necrosis (ATN). Renal recovery is less likely in patients with preexisting renal disease. Renal recovery at hospital discharge may underestimate the true rate of renal recovery. The overwhelming majority of patients (more than 85 %) with severe ATN precipitating on normal renal function recover and maintain complete renal function or any degree of chronic renal functional impairment within 6-12 months after AKI. Partial or nonrecovery of renal function represents an independent predictor of long-term mortality for survivors from AKI. Re-need for RRT occurs in a small portion of survivors of severe ATN (less than 5%).
CONCLUSION: Severe AKI necessitating RRT should no longer simply be viewed as just an acute reversible complication of critical illness or short-term illness. Persistent reduction in renal function will exhibit independent effects on patient survival that extends well beyond discharge from the hospital.