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RENAL FAILURE

RENAL FAILURE. Classifications. Acute versus chronic Pre-renal, renal, post-renal Anuric , oliguric, polyuric. Renal Physiology Review. The Kidneys: Control the fluid/electrolyte balance for the body Remove metabolic wastes from the blood & excrete them to the outside

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RENAL FAILURE

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  1. RENAL FAILURE

  2. Classifications • Acute versus chronic • Pre-renal, renal, post-renal • Anuric, oliguric, polyuric

  3. Renal Physiology Review The Kidneys: • Control the fluid/electrolyte balance for the body • Remove metabolic wastes from the blood & excrete them to the outside • Regulate red-blood cell production • Regulate blood-pressure • Important in calcium ion absorption • Control volume, composition and pH of the blood

  4. Renal Hormone Regulation Synthesis and activation of hormones by the kidney include: • Active form of Vitamin D • Erythropoietin Renal blood flow regulated by: Renin-angiotensinaldosterone system (RAAS)

  5. Fluid and Electrolyte ControlMechanisms • RAAS – Renin-Angiotensin Aldosterone System • Aldosterone • ADH – Anti-Diuretic Hormone

  6. Aldosterone • Increases rate of sodium ion absorption • Chloride moves along with sodium because of + charge of sodium • Increases rate of potassium & hydrogen ion secretion Result: Fluid and sodium retention increases blood-pressure

  7. ACUTE RENAL FAILURE

  8. Acute Renal Failure • Definition • The loss of renal function (measured as GFR) over hours to days • Expressed clinically as the retention of nitrogenous waste products in the blood

  9. Acute Renal Failure • Definitions • Azotemia - the accumulation of nitrogenous wastes • Uremia - symptomatic renal failure • Oliguria - urine output < 400-500 mL/24 hours • Anuria - urine output < 100 mL/24 hours

  10. Causes of ARF • Pre-renal = • vomiting, diarrhea, poor fluid intake, fever, use of diuretics, and heart failure • cardiac failure, liver dysfunction, or septic shock • Intrinsic • Interstitial nephritis, acute glomerulonephritis, tubular necrosis, ischemia, toxins • Post-renal = • prostatic hypertrophy, cancer of the prostate or cervix, or retroperitoneal disorders • neurogenic bladder • bilateral renal calculi, papillary necrosis, coagulated blood, bladder carcinoma, and fungus

  11. Symptoms of ARF • Decrease urine output (70%) • Edema, esp. lower extremity • Mental changes • Heart failure • Nausea, vomiting • Pruritus • Anemia • Tachypenic • Cool, pale, moist skin

  12. Weakness Lethargy Muscle cramps Paresthesias Dysrhythmias Hyperkalemia Symptoms

  13. Hyperkalemia Treatment • Calcium gluconate (carbonate) • Sodium Bicarbonate • Insulin/glucose • Diuretics (Furosemid) • Albuterol • Hemodialysis

  14. Prerenal Acute Renal Failure • Volume Depletion • Decreased effective blood volume • congestive heart failure • cirrhosis • nephrotic syndrome • sepsis • Renal vasoconstriction • hepatorenal syndrome • hypercalcemia • nonsteroidal anti-inflammatory drugs

  15. Prerenal Acute Renal Failure:Clinical Presentation • History • volume loss (e.g., diarrhea, acute blood loss) • heart disease • liver disease • evidence of infection • diuretic use • thirst • orthostatic symptoms

  16. Prerenal Acute Renal Failure:Clinical Presentation • Physical Examination • Blood pressure and pulse • Orthostatic changes in blood pressure • Skin turgor • Dryness of mucous membranes and axillae • Neck veins • Cardiopulmonary exam • Peripheral edema

  17. Prerenal Acute Renal Failure: Clinical Presentation • BUN:Creatinine ratio • > 20:1 • Urine indices • Oliguria • usually < 500 mL/24 hours; but may be non-oliguric • Elevated urine concentration • UOsm > 700 mmol/L • specific gravity > 1.020 • Evidence of high renal sodium avidity • UNa < 20 mmol/L • FENa < 0.01 • Inactive urine sediment

  18. Fractional Excretion of Sodium • Etiologies of a fractional excretion of sodium <0.01 • normal renal function • prerenalazotemia • hepatorenal syndrome • early obstructive uropathy • contrast nephropathy • rhabdomyolysis • acute glomerulonephritis

  19. Treatment of Prerenal Acute Renal Failure • Correction of volume deficits • Discontinuation of antagonizing medications • NSAIDs/COX-2 inhibitors • Diuretics • Optimization of cardiac function

  20. Postrenal Acute Renal Failure • Urinary tract obstruction • level of obstruction • upper tract (ureters) • lower tract (bladder outlet or urethra) • degree of obstruction • partial • complete

  21. Pathophysiology of Renal Failure in Obstructive Uropathy • Early • Increased intratubular pressure • Initial increase followed by decrease in renal plasma flow • Late • Normal intratubular pressure • Marked decrease in renal plasma flow

  22. Upper tract obstruction Intrinsic nephrolithiasis papillary necrosis blood clot transitional cell cancer Extrinsic retroperitoneal or pelvic malignancy retroperitoneal fibrosis endometriosis abdominal aortic aneurysm Lower tract obstruction benign prostatic hypertrophy prostate cancer transitional cell cancer urethral stricture bladder stones blood clot neurogenic bladder Etiologies of Postrenal Acute Renal Failure

  23. Postrenal Acute Renal Failure:Clinical Presentation • History • Symptoms of bladder outlet obstruction • urinary frequency • urgency • intermittency • hesitancy • nocturia • incomplete voiding

  24. Postrenal Acute Renal Failure:Clinical Presentation • History • Changes in urine volume • anuria • polyuria • fluctuating urine volume • Flank pain • Hematuria • History of pelvic malignancy

  25. Postrenal Acute Renal Failure:Clinical Presentation • Physical Examination • Suprapubic mass • Prostatic enlargement • Pelvic masses • Adenopathy

  26. Postrenal Acute Renal Failure:Clinical Evaluation • Diagnostic studies • BUN: Creatinine ratio > 20:1 • Unremarkable urine sediment • Variable urine chemistries

  27. Postrenal Acute Renal Failure:Clinical Evaluation • Diagnostic studies • Post-void residual bladder volume • > 100 mL consistent with voiding dysfunction • Radiologic studies • Ultrasound • CT scan • Nuclear medicine • Retrograde pyelography • Antegrade nephrostograms

  28. Treatment of Postrenal Acute Renal Failure • Relief of obstruction • Lower tract obstruction • bladder catheter • Upper tract obstruction • ureteral stents • percutaneous nephrostomies • Recovery of renal function dependent upon duration of obstruction • Risk of post-obstructive diuresis

  29. Intrinsic Acute Renal Failure • Acute tubular necrosis (ATN) • Acute interstitial nephritis (AIN) • Acute glomerulonephritis (AGN) • Acute vascular syndromes • Intratubular obstruction

  30. Ischemic prolonged prerenal azotemia hypotension hypovolemic shock cardiopulmonary arrest cardiopulmonary bypass Sepsis Nephrotoxic drug-induced radiocontrast agents aminoglycosides amphotericin B cisplatinum acetaminophen pigment nephropathy hemoglobin myoglobin Acute Tubular Necrosis

  31. Pathophysiology of Acute Tubular Necrosis • Mechanisms of decreased renal function • Vasoconstriction • Tubular obstruction by sloughed debris • Backleak of glomerular filtrate across denuded tubular basement membrane

  32. Acute Tubular Necrosis: Clinical Presentation • History • Acute illness • Exposure to nephrotoxins • Episodes of hypotension • Physical examination • Hemodynamic status • Volume status • Features of associated illness • Laboratory data • BUN:Creatinine ratio < 10:1 • Evidence of toxin exposure

  33. Acute Tubular Necrosis: Clinical Presentation • Urine indices • Urine volume • may be oliguric or non-oliguric • Isosthenuric urine concentration • UOsm 300 mmol/L • specific gravity  1.010 • Evidence of renal sodium wasting • UNa > 40 mmol/L • FENa > 0.02 • Urine sediment • tubular epithelial cells • granular casts

  34. Acute Tubular Necrosis:Treatment • Supportive therapy • No specific pharmacologic treatments • Acute dialysis for: • volume overload • metabolic acidosis • hyperkalemia • uremic syndrome • pericarditis • encephalopathy • azotemia

  35. Prognosis ofAcute Tubular Necrosis • Mortality dependent upon comorbid conditions • overall mortality ~ 50% • Recovery of renal function seen in ~ 90% of patients who survive - although not necessarily back to prior baseline renal function

  36. Acute Interstitial Nephritis • Acute renal failure due to lymphocytic infiltration of the interstitium • Classic triad of • fever • rash • eosinophilia

  37. Drug-induced penicillins cephalosporins sulfonamides rifampin phenytoin furosemide NSAIDs Malignancy Idiopathic Infection-related bacterial viral rickettsial tuberculosis Systemic diseases SLE sarcoidosis Sjögren’s syndrome tubulointerstitial nephritis and uveitis Acute Interstitial Nephritis

  38. Acute Interstitial Nephritis:Clinical Presentation • History • preceding illness or drug exposure • Physical examination • fever • rash • Laboratory Findings • eosinophilia

  39. Acute Interstitial Nephritis:Clinical Presentation • Urine findings • non-nephrotic protinuria • hematuria • pyuria • WBC casts • eosinophiluria

  40. Acute Interstitial Nephritis:Treatment • Discontinue offending drug • Treat underlying infection • Treat systemic illness • Glucocorticoid therapy may be used in patients who fail to respond to more conservative therapy

  41. Acute Glomerulonephritis • Nephritic presentation • proteinuria • may be in nephrotic range (> 3 g/day) • hematuria • RBC casts • Diagnosis usually requires renal biopsy

  42. Acute Glomerulonephritis • Etiologies • poststreptococcal glomerulonephritis • postinfectious glomerulonephritis • endocarditis-associated glomerulonephritis • systemic vasculitis • thrombotic microangiopathy • hemolytic-uremic syndrome • thrombotic thrombocytopenic purpura • rapidly progressive glomerulonephritis

  43. Acute Vascular Syndromes • Renal artery thromboembolism • Renal artery dissection • Renal vein thrombosis • Atheroembolic disease

  44. Intratubular Obstruction • Intratubular crystal deposition • tumor lysis syndrome • acute urate nephropathy • ethylene glycol toxicity • calcium oxylate deposition • Intratubular protein deposition • multiple myeloma • -Bence-Jones protein deposition

  45. Differential Diagnosis of Acute Renal Failure • Prerenal ARF • Postrenal ARF • Intrinsic ARF • acute tubular necrosis • acute interstitial nephritis • acute glomerulonephritis • acute vascular syndromes • intratubular obstruction

  46. skin turgor mucosal membrane hydration FENa < 0.01 Acute Renal Failure: Diagnostic Evaluation • Evaluate for prerenal causes • clinical exam • blood pressure • orthostasis • central venous pressures and cardiac output • intake/output record • urine sediment • urine sodium • UNa < 20 mmol/L • therapeutic trial of volume replacement

  47. Acute Renal Failure:Diagnostic Evaluation • Evaluate for postrenal causes • bladder catheterization • renal ultrasound

  48. radiocontrast agents sepsis cells casts Acute Renal Failure:Diagnostic Evaluation • Evaluation for intrinsic ARF • clinical history • medications • hypotension • physical exam • urinalysis • crystals • paraproteins

  49. Diagnostic Evaluation of ARF

  50. Acute Renal Failure: Management • Prerenal ARF • volume repletion • inotropic support • discontinue diuretics • Postrenal ARF • bladder catheterization • percutaneous nephrostomy or ureteral stents • fluid management during post-obstructive diuresis

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