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Acute Kidney Injury. Chapter 47. Acute Kidney Injury Etiology and Pathophysiology. Prerenal Causes are factors external to the kidneys that reduce renal blood flow Severe dehydration, heart failure, ↓ CO Decreases glomerular filtration rate Causes oliguria
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Acute Kidney Injury Chapter 47
Acute Kidney InjuryEtiology and Pathophysiology • Prerenal • Causes are factors external to the kidneys that reduce renal blood flow • Severe dehydration, heart failure, ↓ CO • Decreases glomerular filtration rate • Causes oliguria • Autoregulatory mechanisms attempt to preserve blood flow
Acute Kidney InjuryEtiology and Pathophysiology • Intrarenal • Causes include conditions that cause direct damage to kidney tissue • Results from • Prolonged ischemia • Nephrotoxins • Hemoglobin released from hemolyzed RBCs • Myoglobin released from necrotic muscle cells
Acute Kidney InjuryEtiology and Pathophysiology • Intrarenal • Acute tubular necrosis (ATN) • Results from ischemia, nephrotoxins, or sepsis • Severe ischemia causes disruption in basement membrane • Nephrotoxic agents cause necrosis of tubular epithelial cells • Potentially reversible
Acute Kidney InjuryEtiology and Pathophysiology • Postrenal • Causes include • Benign prostatic hyperplasia • Prostate cancer • Calculi • Trauma • Extrarenal tumors
Case Study iStockphoto/Thinkstock • J.K. is a 37-year-old man who fell off the roof of a house he was constructing. • He sustained severe lacerations of his face and left leg, with substantial blood loss.
Case Study iStockphoto/Thinkstock • Which type of kidney injury is J.K. at risk for? • What are the contributing factors for this? • What signs and symptoms of renal involvement would you assess for?
Acute Kidney InjuryClinical Manifestations • RIFLE classification • Risk (R) • Injury (I) • Failure (F) • Loss (L) • End-stage kidney disease (E)
Acute Kidney InjuryClinical Manifestations • Oliguric phase • Urinary changes • Urinary output less than 400 mL/day • Occurs within 1 to 7 days after injury • Lasts 10 to 14 days • Urinalysis may show casts, RBCs, WBCs
Acute Kidney InjuryClinical Manifestations • Oliguric phase • Fluid volume • Hypovolemia may exacerbate AKI • With decreased urine output, fluid retention occurs • Neck veins distended • Bounding pulse • Edema • Hypertension • Fluid overload can lead to heart failure, pulmonary edema, and pericardial and pleural effusions
Acute Kidney InjuryClinical Manifestations • Oliguric phase • Metabolic acidosis • Serum bicarbonate level decreases • Severe acidosis develops • Kussmaul respirations • Sodium balance • Increased excretion of sodium • Hyponatremia can lead to cerebral edema • Potassium excess • Usually asymptomatic • ECG changes
Acute Kidney InjuryClinical Manifestations • Oliguric phase • Hematologic disorders • Leukocytosis • Waste product accumulation • Elevated BUN and serum creatinine levels • Neurologic disorders • Fatigue and difficulty concentrating • Seizures, stupor, coma
Case Study iStockphoto/Thinkstock • J.K.’s injuries have been repaired, but his urine output has dropped below 350 mL/day. • J.K.’s laboratory results reveal BUN 53 mg/dL and serum creatinine 2.7 mg/dL. • He complains of fatigue. • His BP has risen to 178/98.
Case Study iStockphoto/Thinkstock • What other manifestations should you observe for? • What other laboratory results should you monitor? • J.K.’s urine output suddenly increases to 2 L overnight. Is this a positive sign?
Acute Kidney InjuryClinical Manifestations • Diuretic phase • Daily urine output is 1 to 3 L • May reach 5 L or more • Monitor for hyponatremia, hypokalemia, and dehydration • Recovery phase • May take up to 12 months for kidney function to stabilize
Audience Response Question Which assessment would indicate to the nurse that a patient has oliguria related to an intrarenal acute kidney injury? • Urinary sodium levels are low. • The serum creatinine level is normal. • Oliguria is relieved after fluid replacement. • Urine testing reveals a specific gravity of 1.010.
Acute Kidney Injury • Diagnostic studies • Thorough history • Serum creatinine • Urinalysis • Kidney ultrasonography • Renal scan • Computed tomography (CT) scan • Renal biopsy
Acute Kidney Injury • Diagnostic studies • Contraindicated • Magnetic resonance imaging (MRI) • Magnetic resonance angiography (MRA) with gadolinium contrast medium • Nephrogenic systemic fibrosis • Contrast-induced nephropathy (CIN)
Case Study iStockphoto/Thinkstock • J.K.’s urinalysis reveals slight hematuria and a low specific gravity. • Renal ultrasound findings are normal. • What is the overall goal in the management of J.K. at this point? • What nursing interventions would you implement?
Acute Kidney Injury • Collaborative care • Primary goals • Eliminate the cause • Manage signs and symptoms • Prevent complications
Acute Kidney Injury • Collaborative care • Ensure adequate intravascular volume and cardiac output • Force fluids • Loop diuretics (e.g., furosemide [Lasix]) • Osmotic diuretics (e.g., mannitol) • Closely monitor fluid intake during oliguric phase
Acute Kidney Injury • Collaborative care • Hyperkalemia • Insulin and sodium bicarbonate • Calcium carbonate • Sodium polystyrene sulfonate (Kayexalate)
Acute Kidney Injury • Collaborative care • Indications for renal replacement therapy (RRT) • Volume overload • Elevated serum potassium level • Metabolic acidosis • BUN level higher than 120 mg/dL (43 mmol/L) • Significant change in mental status • Pericarditis, pericardial effusion, or cardiac tamponade
Acute Kidney Injury • Collaborative care • Renal replacement therapy (RRT) • Peritoneal dialysis (PD) • Intermittent hemodialysis (HD) • Continuous renal replacement therapy (CRRT) • Cannulation of artery and vein
Acute Kidney Injury • Collaborative care • Nutritional therapy • Maintain adequate caloric intake • Restrict sodium • Increase dietary fat • Enteral nutrition
Case Study iStockphoto/Thinkstock • J.K. continues to improve, but he has lost 6 lb since admission. • He expresses concern regarding maintaining muscle mass and his ability to perform his job as a construction worker after discharge.
Nursing ManagementAcute Kidney Injury • Nursing assessment • Measure vital signs • Measure fluid intake and output • Examine urine • Assess general appearance • Observe dialysis access site
Nursing ManagementAcute Kidney Injury • Nursing assessment • Mental status and level of consciousness • Oral mucosa • Lung sounds • Heart rhythm • Laboratory values • Diagnostic test results
Nursing ManagementAcute Kidney Injury • Nursing diagnoses • Excess fluid volume • Risk for infection • Fatigue • Anxiety • Potential complication: dysrhythmia
Nursing ManagementAcute Kidney Injury • Planning • The patient with AKI will • Completely recover without any loss of kidney function • Maintain normal fluid and electrolyte balance • Have decreased anxiety • Comply with and understand the need for careful follow-up care
Nursing ManagementAcute Kidney Injury • Nursing implementation • Health promotion • Identify and monitor populations at high risk • Control exposure to nephrotoxic drugs and industrial chemicals • Prevent prolonged episodes of hypotension and hypovolemia
Nursing ManagementAcute Kidney Injury • Nursing implementation • Health promotion • Monitor intake and output • Monitor electrolyte balance • Measure daily weight • Replace significant fluid losses • Provide aggressive diuretic therapy for fluid overload • Use nephrotoxic drugs sparingly
Nursing ManagementAcute Kidney Injury • Nursing implementation • Acute intervention • Accurate intake and output measurements • Daily weights • Assessment for signs of hypervolemia or hypovolemia • Meticulous aseptic technique • Careful administration of nephrotoxic drugs • Skin care measures • Mouth care
Case Study iStockphoto/Thinkstock • J.K. progresses well and is preparing for discharge. • His BUN is 19 mg/dL, serum creatinine is 1.4 mg/dL, and urinalysis is normal. • J.K. has gained 2 lb since his nutritional needs were addressed.
Nursing ManagementAcute Kidney Injury • Nursing implementation • Ambulatory and home care • Regulate protein and potassium intake • Follow-up care • Teaching • Appropriate referrals
Nursing ManagementAcute Kidney Injury • Nursing implementation • Evaluation • The expected outcomes are that the patient with AKI will • Regain and maintain normal fluid and electrolyte balance • Comply with the treatment regimen • Experience no untoward complications • Have complete recovery
Gerontologic ConsiderationsAcute Kidney Injury • More susceptible to AKI • Polypharmacy • Hypotension • Diuretic therapy • Aminoglycoside therapy • Obstructive disorders • Surgery • Infection