Management of Secondary Acute Renal Failure in Critical Ill Patient

Abstract

Acute renal failure (ARF) is a common clinical event affecting 2-5% of hospitalized patients and up to 10-30% of those in intensive care units (ICU), depending on the population studied and the criteria used to define (Piccinni et al., 2004). Acute renal failure is characterized by a rapid decline in renal function accompanied by retention of nitrogenous waste products and electrolyte disorders, an acute and sustained increase in serum creatinine of 0.5 mg/dL (44.2 mmol/L), if the baseline is less than 2.5 mg/dL (221 mmol/L), or an increase in serum creatinine by more than 20% if the baseline is more than 2.5 mg/dL (221 mmol/L) is important laboratorysign in diagnosis of acute renal failure (Amy, 2008). Until recently, a systematic definition of acute renal failure (ARF) was lacking, which led to significant confusion both clinically and in the medical literature. In 2004, the Acute Dialysis Quality Initiative (ADQI) group published the RIFLE (Risk of renal dysfunction, Injury to the kidney, Failure of kidney function, Loss of kidney function and End-stage kidney disease) classification of ARF, based on changes from the patient's baseline either in serum creatinine level or in glomerular filtration rate (GFR) or urine output (UO) (Bellomo et al., 2004). Acute renal failure is similar to the acute respiratory distress syndrome (ARDS) in that it is not a primary disease, but is a complication of other disease, most notably severe sepsis and septic shock, and is often part of the multiple organ failure (MOF) syndrome. (Bellomo, 2005) In critically ill patients, more than 90% of ARF episodes are of ischemic etiology, which is named hypoperfusion renal failure, or toxic etiology, which is named nephrotoxic renal failure or a combination of both. However, numerous other etiologies of ARF have been identified. Examples include obstruction of the urine outflow tract, acute tubulo-interstitialnephritis and acute glomerulonephritis (Hoste and Kellum, 2004).Clinical problems caused by ARF are metabolic acidosis, electrolytes disturbance from impaired renal excretion of electrolytes and hydrogen ions, and volume overload, which will need in severe cases to urgent dialysis (Kathleen, 2008). For early diagnosis of ARF, the plasma concentrations of urea, creatinine, and electrolytes should be measured on admission of all critically ill patients, and repeated daily or on alternate days, together with the inspection of daily urine output (to discover oliguria or anuria), fluid-balance charts, daily weighing, and the recording of blood pressure, these measurements will ensure that advanced acute renal failure does not suddenly appear in patients already in hospital (Firth, 1998). It is important to prevent and early management of even the mildest forms of ARF. The goals of preventive strategies for ARF are to preserve renal functions, to prevent complications of ARF (volume overload, metabolic acidosis and electrolyte abnormalities) and to prevent the need for chronic dialysis. The preventive strategies have been grouped into nonpharmaco-logical and pharmacological types (Venkataraman, 2005). Clinical advances of pharmacological therapy in the treatment of ARF have been limited. Multiple pharmacologic interventions showed promise in animal models of ARF; however, no agents have proven to be effective in the clinical setting. As a result, the management of ARF remains primarily supportive; renal replacement therapy (RRT) and its modalities serve as the cornerstone of treatment in patients who have persistent severe acute renal dysfunction (Palevsky, 2005). Intermittent hemodialysis (IHD), continuous renal replacement therapies (CRRT) and sustained lowefficiency dialysis (SLED) are the principal RRT modalities that are used in the acute setting (Fieghen et al., 2009).Although institutional policies may determine the local availability of these modalities, CRRT and SLED tend to be used in patients with greater hemodynamic instability (Fieghen et al., 2009). Intermittent hemodialysis is typically administered with conventional dialysis machinery that is used in the chronic dialysis population with session length ranging from 3 to 5 hours (Fieghen et al., 2009). Continuous renal replacement therapy is applied with an intended treatment time of 24 hours and generally requires dedicated machines that operate at comparatively lower blood and dialysate pump speeds (Fieghen et al., 2009). Continuous renal replacement therapy may be administered as hemodialysis (continuous venovenous hemodialysis, CVVHD), hemofiltration (continuous venovenous hemofiltration, CVVH) or a combination of these (continuous venovenous hemodiafiltration, CVVHDF) (Fieghen et al., 2009). Sustained low-efficiency dialysis sometimes referred to as extended dialysis, is considered a „hybrid‟ of IHD and CRRT. SLED is administered using conventional dialysis technology but typical sessions run for 8–12 h using blood and dialysis flows that are intermediate to those prescribed in IHD and CRRT (Fieghen et al., 2009).