Acute Renal Failure
Evaluation of acute renal failure requires careful review of clinical history and physical examination. Baseline renal status should be obtained along with vital signs, chest X-ray, and pertinent laboratory studies, including blood urea nitrogen/creatinine (BUN/Crt), hemoglobin/hematocrit, and electrolytes. Acute kidney injury (AKI) is diagnosed when a patient meets any one of the following criteria: (1) an increase in serum creatinine by ≥0.3 mg/dl within 48 h, (2) an increase in serum creatinine ≥1.5 times the patient’s baseline, or (3) a urine volume ≤0.5 ml/kg/h for 6 h. Etiology of AKI is broad and includes hypovolemia, intrinsic renal disease, exposure to nephrotoxic agents, as well as obstructive pathology. Classification systems such as RIFLE (Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease) can assist in clinical evaluation. To help differentiate etiology, a clinician should first rule out common post-renal causes with renal ultrasound. Urinalysis in addition to urine electrolytes should be obtained if renal ultrasound is found to be negative. The fluid challenge is the gold standard used to assess fluid responsiveness and to guide fluid administration. The most common approach involves the administration of 500 cc crystalloid within a 30-minute time frame. Urine output guides fluid resuscitation in addition to blood pressure, heart rate, and both invasive and noninvasive monitoring. Early renal replacement therapy (RRT) results in better clinical outcomes. Hemodynamic stability should be taken into consideration prior to initiation of RRT.
KeywordsAcute kidney injury Acute renal failure Renal ultrasound Urinalysis Urine electrolytes Compartment syndrome Pre-renal Renal Post-renal Renal replacement therapy Hemodialysis Continuous veno-venous hemofiltration