Episode Details

1. Pathophysiology

• AKI: Sudden, potentially reversible decline in GFR.
  • Prerenal: Decreased perfusion (hypovolemia, shock, HF). Oliguria occurs without tissue damage; reversible with fluids.
  • Intrarenal: Direct tissue damage, 90% from Acute Tubular Necrosis (ATN) (ischemia, sepsis, nephrotoxins).
  • Postrenal: Mechanical obstruction (BPH, calculi) causing urine reflux.
• CKD: Gradual, irreversible nephron loss (GFR <60 for >3 months). Primary causes: Diabetes (50%), Hypertension (25%). Stage 5 (ESRD) GFR <15.

2. Clinical Phases & Manifestations

• AKI Phases:
  • Oliguric (<400 mL/d): Fluid overload (edema, hypertension, pulmonary edema), acidosis, hyperkalemia (ECG: peaked T, wide QRS), and uremia.
  • Diuretic (1–5+ L/d): Osmotic diuresis (high urea). Risk of hypovolemia, hypotension, hyponatremia, and hypokalemia.
  • Recovery: GFR increases, BUN/Creatinine stabilize (takes up to 12 months).
• CKD Manifestations (Uremia):
  • Cardiovascular: Leading cause of death; due to vascular calcification, volume overload, and hypertension.
  • Hematologic: Anemia from decreased erythropoietin.
  • CKD-MBD: Low active Vitamin D reduces calcium absorption. Hypocalcemia triggers PTH release, causing bone demineralization (osteomalacia, osteitis fibrosa) and calcifications.

3. Diagnostics & Priority Interventions

• Metrics: GFR is the best indicator of kidney function. Creatinine is the best AKI marker. Proteinuria is first sign of CKD.
• Hyperkalemia Emergency Care:
  • Cardioprotection: IV Calcium Gluconate (stabilizes myocardium).
  • Shift K+ Intracellularly: IV Regular Insulin + Glucose, or IV Sodium Bicarbonate.
  • Definitive Removal: Hemodialysis or Kayexalate (avoid in paralytic ileus due to bowel necrosis).
• Fluid Limits: Oliguric AKI: previous 24-hr loss + 600 mL.
• Anemia: Exogenous EPO. Monitor for hypertension, clots; supplement iron.

4. RRT & Post-Op Care

• HD: Rapid fluid/solute shifts. Assess AV Fistula for thrill and bruit. Safety: No BP/blood draws/IVs in access arm. Complication: Hypotension, cramps.
• PD: Uses peritoneal membrane. Core complication: Peritonitis (abdominal pain, rebound tenderness, cloudy effluent).
• CRRT: Slow, continuous solute/fluid removal for hemodynamically unstable AKI.
• Transplantation: Post-op priority is fluid/electrolyte balance. Watch for massive diuresis (replace mL-for-mL) or ATN. CVD is the leading cause of death post-transplant.