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Back to Basics: Acute Renal Failure

Back to Basics: Acute Renal Failure

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Back to Basics: Acute Renal Failure

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  1. Back to Basics:Acute Renal Failure

  2. 1% of patients have ARF at time of admission • 2-5% develop ARF during hospitalization • Important to recognize and manage patients early since mortality rate increases in patients with ARF - 40-50% in general ward - 80-90% in patients in the ICU

  3. Acute Renal Failure: Definition • Acute rise in serum creatinine from baseline (increase of at least 0.5 mg/dl) • Oliguria or anuria may or may not be present • Oliguria - < 400 ml/day • Anuria - < 50 ml/day

  4. Anuria vs. oliguria vs. non-oliguria • Anuria - < 50ml/day • If abrupt, consider: • Obstruction • vast majority of patients with anuria • Bilateral renal cortical necrosis • Fulminant glomerulonephritis • usually some type of rapidly progressive glomerulonephritis • Acute bilateral renal artery or vein occlusion (rare) • Oliguria - <400ml/day

  5. Is it ARF or acute on chronic renal failure? • Is there renal tract obstruction • Is there a reduction in effective ECF? • Has there been a major vascular occlusion? • Is there parenchymal disease other than ATN?

  6. Types of Acute Renal Failure

  7. Exclude pre-renal and post- obstructive first then look for possible causes of intrinsic renal failure

  8. Prerenal Acute Renal Failure • True Intravascular depletion • Sepsis, hemorrhage, overdiuresis, vomiting, diarrhea, burns • Decreased effective volume to the kidneys • CHF, cirrhosis, hepatorenal syndrome, nephrotic syndrome, anaphylaxis • Impaired renal autoregulation • Pre-glomerular (afferent arteriolar) vasoconstriction • Sepsis, Hypercalcemia, Hepatorenal syndrome • NSAIDS, cyclosporine, Amphotericin, epinephrine • Postglomerular (efferent arteriolar) vasodilation • ACE Inhibitors, AT1 receptor antagonist

  9. Postrenal or Postobstructive ARF • Intratubular obstruction • Uric acid nephropathy • Methotrexate crystal deposition • myeloma light chain • Ureteric obstruction • Retroperitoneal Disorders – fibrosis or malignancies • Cervical Cancer • Pelvic mass or invasive pelvic malignancies • Intrinsic causes/ Intraluminal • Nephrolithiasis • Necrotic papillae • Blood clots or fungus ball • Urethral obstruction • Benign Prostatic Hyperplasia • Neurogenic Bladder • Urethral strictures

  10. Types of Acute Renal Failure

  11. Drugs Associated with ARF

  12. Types of Acute Renal Failure

  13. History • Pulmonary symptoms • Sinus or URI or hemoptysis • Cardiac • CHF, Valvular Disease • GI • Diarrhea, vomiting, poor intake • Flank pain, colicky abdominal pain • Musculoskeletal • Trauma, joint pain, arthritis • GU • BPH, history of stones, recurrent UTI

  14. History • Chart Review • I/O, hypotension, drugs, procedures • Skin • Rash, skin infections • Drug History • ACE In, NSAIDs, antibiotics, antivirals, IVDA • Past Medical History • DM, HTN, multiple sclerosis, stroke, previous malignancy • Past Surgical History and procedures • CABG, angiogram, CT *Stratify as to severity of symptoms Determine if there are symptoms of uremia

  15. What P.E. findings would be helpful?

  16. Key Points in Physical Examination • Vital signs • Temperature • infection • Blood Pressure • orthostatic hypotension for volume • Malignant hypertension • Weight loss or gain • Mouth • Jugular veins • Pulmonary and Cardiovascular System • Abdomen • Pelvis • Rectum • Skin • Petechaie, rash, gangrene, livedo

  17. What laboratory tests will you order?

  18. Laboratory Evaluation • BUN and creatinine • Electrolytes • Arterial blood gas • CBC and peripheral blood smear • Radiologic procedures • Urinalysis • Urine electrolytes • Urinary sediment

  19. Prerenal ARF Scant; few hyaline casts, Specific gravity increased Postrenal ARF Scant; few hyaline cast, possible red cells SG inc early; 1.010-1.012 late in course Sediment Characteristics

  20. ATN- epithelial cells, muddy-brown casts, WBC cells, low-grade proteinuria, SG increased Allergic interstitial nephritis- wbc, rbc, epithelial cells, eosinophils, WBC cast, low to moderate grade proteinuria, SG 1.010-1.012 GN- RBC cast, dysmorphic RBC, moderate to severe proteinuria, SG 1.010-1.012 Sediment Characteristics

  21. * FENa - helps detect an extreme renal avidity for sodium • (i.e.,pre-renal azotemia, hepatorenal syndrome) • FENa = (UNa/PNa) / (UCr/PCr) X 100 • * The FENa assay is useful in ARF only in the presence of oliguria. • * Exceptions to this rule • -ATN caused by radiocontrast nephropathy or severe burns. • -in liver disease, FENa can be < 1% in the presence of ATN. • -administration of diuretics, AIN may cause the FENa > 1%

  22. Renal Ultrasound • Pelvicalyceal dilatation- obstruction • Shrunken kidneys- Chronic kidney disease • Normal size- echogenic: acute GN, ATN • Normal echo pattern: pre-renal, renal artery occlusion • Enlarged kidneys: malignancy, HIV, renal vein thrombosis, amyloid

  23. General Treatment Guidelines • Correct fluid and electrolyte imbalance • Volume depletion • Hyperkalemia • Metabolic acidosis • Nutritional support • 30-45 kcal/ kg/ day • 0.6 g/kg protein restriction (1-1.5g/kg if on dialysis) • restrict K (<40mmol/day) • restrict phosphate <800mg/day • Fluid restriction if anuria or oliguria present • Look for underlying cause • Avoid nephrotoxic agents and adjust medications • Uremia management • Indications for dialysis

  24. Complications of ARF • Metabolic • Hyponatremia, hyperkalemia, hypocalcemia, hyperphosphatemia, hypermagnesemia, hyperuricemia • Cardiovascular • CHF, arrhythmias, HTN, pericarditis • Neurologic • Asteixis, somnolence, coma, seizures • Hematologic • Anemia, coagulopathies, hemorrhagic diathesis • Gastrointestinal • Nausea, vomiting • Infectious

  25. Indications for Dialysis • Uremia • Refractory hyperkalemia • Refractory fluid overload • Use diuretics- use step-wise approach • Refractory metabolic acidosis • If pH<7.2 despite NaHCO3 • If patient cannot tolerate bicarbonate infusion due to fluid overload

  26. Prognosis • Factors: • Cause of renal failure • Duration of renal failure prior to therapeutic intervention. even if renal failure is mild, the mortality rate is 30-60%. If these patients need dialytic therapy, the mortality rate is 50-90%. • Mortality rate • 31% in patients with normal urine sediment test results • 74% in patients with abnormal urine sediment test results. • APACHE SCORE • survival rate is nearly 0% among patients with ARF who have a score higher than 40 • 40% in patients with APACHE II scores of 10-19. • Other prognostic factors include the following: • Older age • Multiorgan failure (ie, the more organs that fail, the worse the prognosis) • Oliguria • Hypotension • Vasopressor support • Number of transfusions • Noncavitary surgery

  27. Contrast-induced Nephropathy • Risk Factors: • Diabetes • previous CRI • contrast load • Age • Dehydration • nephrotoxic agent • Other diseases: • myeloma, CHF, liver disease

  28. Contrast-induced Nephropathy • Intervention • Identify risk prior to procedure • Avoid volume depletion • Hydrate to keep urine output >150 ml/hr pre-proc, during and 12 hours postprocedure • Use non-ionic low osmolality in diabetics and CKD patients • Minimize contrast volume • N-acetylcysteine 600 mg twice a day starting one day before and until 48 hours post-procedure • Space contrast procedures by at least five days • Prognosis • Increased risk of mortality especially in patients needing dialytic therapy (35% vs. 7.1% vs. 1%)

  29. Medications • Prophylactic medication • N-acetylcysteine – 600 mg PO q 12 • Diuretics • Dopamine- renal-dose • Calcium-channel blockers

  30. CASE • 65 y/o diabetic, at the ER with RUQ pain that raidates to the back, nausea, vomiting, anorexia, light-headedness and decreased urine output in the past 24 hours • PE: • BP: supine:110/70, PR=80 • Standing: 85/60; 115 • Poor skin turgor, RUQ tenderness • Labs: WBC:19, BUN= 35; crea= 1.6; Na= 146; k=4.1; cl=111; ast=35; alkp=289; urinalysis: ph=5,SG=1.028;Una=10, Ucrea=80, no sediment

  31. Patient remained hypotensive, given gentamicin and ampicillin for acute cholecystitis • Urine output: 100 in 12 hours • Labs:Na=140, k=5, cl=100, CO2=15, BUN 40, crea 2.5, urinalysis= SG=1.010, brown muddy cast, Una=80, Ucrea, 40, (+) blood cultures • Patient remains oliguric for 3 days, Bun and crea inc to 110, 5.5

  32. What is your diagnosis? • What treatment would you give?

  33. Back to Basics:Acute Renal Failure Yvette Talusan- Tomacruz, M.D. National Kidney and Transplant Institute

  34. PatientEvaluation • Determine if pre-renal, intrinsic or post-obstructive • 60-70 % - pre-renal • 25-40 % - intrinsic • 5-10 % - obstruction • KEY: History and Physical examination

  35. Intrinsic Acute Renal Failure • Acute tubular necrosis • Ischemia • Toxins • drugs, contrast agents, pigments • Glomerular disease • RPGN, SLE, small-vessel vasculitis, HSP, Goodpasture’s syndrome ,Acute proliferative GN- PSGN,PIGN, endocarditis • Vascular disease • Microvascular disease • Atheroembolic disease, TTP, HUS, HELLP • Macrovascular disease • RAS, Aneurysm • Others • Allergic reaction to drugs • Autoimmune Disease • Pyelonephritis • Infiltrative Disease