Acute Renal Failure Level Basic Version No Version
Acute Renal Failure Level: Basic Version No: Version Date: February 2012 Authors: Marcono R. Hines Jr. , M. D. and Ruediger W. Lehrich, M. D. Affiliation: Duke University Medical Center L. I. T. Reviews
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Learning Objectives • • • Definition of acute renal failure Description of causes of acute renal failure Symptoms of acute renal failure Evaluation of a patient with acute renal failure Treatment and when to provide renal replacement therapy. L. I. T. Reviews
Outline • • What is acute renal failure? Causes of acute renal failure. Physical exam and laboratory evaluation. Treatment and indications to provide acute dialysis. L. I. T. Reviews
Definition • A rapid decline in the glomerular filtration rate (GFR) that occurs over a period of hours to weeks. • Increase in blood urea nitrogen (BUN) or serum creatinine • Requirement of renal replacement therapy. • Reduction in urine output to less than 0. 5 m. L/kg/hr L. I. T. Reviews
Urine Output • Oliguric Renal Failure < 400 m. L/24 hr • Non-oliguric Renal Failure > 400 m. L/24 hr • Anuric Renal Failure < 100 m. L/24 hr L. I. T. Reviews
Categories of Acute Renal Failure (ARF) • Prerenal ARF results from decreased renal plasma flow. 1. 2. 3. 4. 5. Hypovolemia (dehydration or hemorrhage) Cardiogenic shock Sepsis Drugs i. e. NSAIDS Renal artery stenosis L. I. T. Reviews
Intrinsic Renal Failure • Intrinsic or Intrarenal ARF results from injury within the nephron unit. 1. 2. 3. 4. L. I. T. Reviews Acute Tubular Necrosis (ATN) Acute Interstitial Nephritis (AIN) Glomerulonephritis Thromboembolism
Postrenal Acute Renal Failure • Postrenal ARF is caused by urinary outflow obstruction. 1. 2. 3. 4. Prostate disease Kidney Stones Pelvic Tumors Recent Pelvic Surgery L. I. T. Reviews
History And Physical Exam • • Vitals i. e. orthostatic blood pressures Mucous membranes: moist or dry Neck veins, S 3 heart sounds, pericardial friction rub Lung examination: listen for crackles Abdomen: feel for bladder fullness. Lower extremity edema Skin L. I. T. Reviews
Evaluation • • • Obtain U/A: (RBCs, casts, WBCs) Urine electrolytes Serum electrolytes Place foley catheter or obtain bladder scan Renal Ultrasound Fractional excretion of Sodium (Na) – Fe. Na = (Urine. Na/Plasma. Na ) / (Urine. Cr / Plasma. Cr ) – Fe. Na < 1%, Urine Na < 20, and BUN/Cr ratio > 20 suggest a prerenal cause. L. I. T. Reviews
Urine Sediment Etiology Hyaline Cast Prerenal Red cell cast, red cells Glomerulonephritis (intrinsic) White cells, white cell casts, Allergic tubulointerstitial +/- eosinophils nephritis (intrinsic) Granular casts, renal tubular cells L. I. T. Reviews Acute Tubular Necrosis (intrinsic)
Indications for Dialysis • • • Acidosis Electrolyte abnormalities (K > 6. 5 m. Eq/L) Ingestions Overload (fluid) Uremic symptoms (pericarditis, encephalopathy) L. I. T. Reviews
Summary • Acute renal failure is defined as a rapid decrease in GFR. which will be noted by a rise in serum Cr or BUN. • There are pre-renal, intrinsic, and post renal causes. • History and Physical Examination are key to making diagnosis. • Check urinalysis, urine electrolytes, serum electrolytes, and renal ultrasound. • Dialysis as indicated. L. I. T. Reviews
Key References • Greenberg, Cheung, Coffman, Falk, and Jennette. (2009) Primer on Kidney Diseases 5 th edition. Philadelphia, PA. Saunders Elsevier. L. I. T. Reviews
Acknowledgements L. I. T. Reviews
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