Overview
This lecture reviews acute and chronic kidney failure, their causes, assessment findings, complications, and nursing interventions, highlighting key concepts and lab values for nursing exams.
Acute vs. Chronic Kidney Failure
- Acute kidney failure (AKI) is sudden loss of kidney function, often reversible if treated promptly.
- Chronic kidney disease (CKD) is progressive, permanent kidney damage developing over years.
- AKI can be caused by pre-renal (decreased blood flow), intra-renal (direct kidney damage), or post-renal (urine outflow blockage) factors.
- CKD typically results from long-term uncontrolled diabetes, hypertension, or autoimmune disorders.
Causes & Pathophysiology of AKI
- Pre-renal: Decreased perfusion from shock, blood loss, dehydration, or low cardiac output.
- Intra-renal: Direct kidney damage from infections, CT contrast dye, "mycin" antibiotics, NSAIDs.
- Post-renal: Urine outflow obstruction from kidney stones, tumors, or BPH (enlarged prostate).
Assessment and Lab Values
- Waste products filtered by kidneys: Hydrogen ions (acidic), urea, creatinine.
- Key lab values: Creatinine >1.3 mg/dL, BUN >20 mg/dL, urine output <30 mL/hr or <400 mL/day.
- Metabolic acidosis: pH <7.35.
Phases of Acute Renal Failure
- Oliguric: Urine output <400 mL/24hr, high specific gravity, symptoms include anorexia, nausea, vomiting.
- Diuretic (polyuric): High urine output (3–6 L/day), low specific gravity.
- Recovery: Gradual return to normal, may take up to 1 year.
Treatment of AKI
- Main goal: Prevent further kidney damage—use fluid bolus or diuretics like furosemide to induce diuresis.
Chronic Kidney Disease & ESRD
- Staged by GFR: Normal >90, stage 4 (15–29), stage 5 (<15) is end-stage renal disease (ESRD).
- ESRD requires dialysis or transplant; kidneys can no longer filter waste.
Causes and Diagnosis of CKD
- Common causes: Diabetes, hypertension, chronic infection, polycystic kidney disease, unresolved AKI.
- Diagnosis: Creatinine clearance test—collect all urine for 24 hours, discard first specimen, store on ice.
Symptoms and Complications of CKD/ESRD
- Oliguria (<400 mL/day), fluid overload, hypertension crisis (headache, nausea/vomiting, mental changes; report immediately).
- Other signs: Pulmonary crackles, JVD, bounding pulses, anemia (low RBCs), uremic frost (itchy skin).
- Electrolyte imbalances: Hypernatremia (>145), hyperphosphatemia (>4.5), hypocalcemia, hyperkalemia (>5.0)—life-threatening cardiac arrhythmias.
Hyperkalemia Management
- Priority: IV calcium gluconate for dysrhythmias, then IV 50% dextrose + regular insulin, polystyrene sulfonate (Kayexalate), or dialysis.
- Monitor for ECG changes: peaked T-waves, ST elevation, wide QRS complexes, bradycardia.
Nursing Interventions
- Weigh daily at same time; >1 kg gain means 1 L fluid retained—report promptly.
- Avoid nephrotoxic drugs: NSAIDs, "mycin" antibiotics, CT contrast, milk of magnesia.
- Hemodialysis used for blood filtration until transplant possible.
Key Terms & Definitions
- AKI (Acute Kidney Injury) — sudden loss of kidney function.
- CKD (Chronic Kidney Disease) — gradual, irreversible kidney damage.
- GFR (Glomerular Filtration Rate) — measure of blood filtered by kidneys per minute.
- Oliguria — urine output <400 mL/24hr.
- Creatinine Clearance Test — 24-hour urine test for kidney filtering efficiency.
- Hyperkalemia — high blood potassium, risk for fatal heart arrhythmias.
- Hemodialysis — machine-based blood filtering for renal failure.
Action Items / Next Steps
- Memorize lab value cutoffs: creatinine >1.3, BUN >20, potassium >5.0, sodium >145, phosphorus >4.5.
- Practice 24-hour urine collection steps.
- Review acute vs. chronic renal failure causes and phases.
- Know emergency management for hyperkalemia.
- Avoid nephrotoxic medications in at-risk patients.