Acute Renal Failure and Renal Replacement Techniques

Acute renal failure (ARF) is a common event in critical patients usually taking place in a multiorganic failure context. This disorder implies a great clinical challenge. ARF could be defined as a sudden deterioration of the renal function that results in a loss of electrolyte, acid-base and fluid balance control, with subsequent accumulation of nitrogen wastes. Although ARF can appear in a wide range of pa- tients and conditions, its physiopathological bases is shared by most episodes with the hipoperfusion and/or renal ischemia as a triggering of the injury. Shock, and spe- cially septic shock is the main cause of ARF leading to renal replacement techniques. Though in the last twenty years continuous extracorporeal purification techniques have experienced an extraordinary growth, mortality remains high (50-70%). At pre- sent predominance of the continuous renal replacement therapy (CRRT) versus in- termittent hemodialysis (IHD) is based on its better hemodynamic stability, great ver- satility in the hydroelectrolytic handling, favored gaseous exchange and improvement of the ventricular filling pressures, low extracorporeal blood volume, smaller activa- tion of the complement, preferred elimination of fluids from the interstitial space, low rate of complications, control of uremia and the intravascular volume without protein or hydric restriction, possibility of elimination of certain toxics, good tolerance in pa- tients with intracranial hypertension and no need of specialized personnel. CRRT and related procedures are an effective and feasible treatment in patients with acute renal failure, severe cardiovascular instability, multisystem organ failure or politraumatized patients, being a simple and easy choice to implement and monitor. KEY WORDS—Acute renal failure. Continuous renal replacement therapy. Hemo- dialysis. Acute kidney injury. Renal replacement techniques.