CC CJM | CKD v AKI

80/20 Clinical Summary: Renal Failure (AKI vs. CKD)

1. Pathophysiology

• AKI: Sudden, potentially reversible decline in GFR[1].
  • Prerenal: Decreased perfusion (hypovolemia, shock, HF). Oliguria occurs without tissue damage; reversible with fluids[1][2].
  • Intrarenal: Direct tissue damage, 90% from Acute Tubular Necrosis (ATN) (ischemia, sepsis, nephrotoxins)[2].
  • Postrenal: Mechanical obstruction (BPH, calculi) causing urine reflux[3].
• CKD: Gradual, irreversible nephron loss (GFR <60 for >3 months)[4]. Primary causes: Diabetes (50%), Hypertension (25%)[4]. Stage 5 (ESRD) GFR <15[5].

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[3][6].
  • Diuretic (1–5+ L/d): Osmotic diuresis (high urea). Risk of hypovolemia, hypotension, hyponatremia, and hypokalemia[7].
  • Recovery: GFR increases, BUN/Creatinine stabilize (takes up to 12 months)[7].
• CKD Manifestations (Uremia):
  • Cardiovascular: Leading cause of death; due to vascular calcification, volume overload, and hypertension[8][9].
  • Hematologic: Anemia from decreased erythropoietin[10].
  • CKD-MBD: Low active Vitamin D reduces calcium absorption[11]. Hypocalcemia triggers PTH release, causing bone demineralization (osteomalacia, osteitis fibrosa) and calcifications[12].

3. Diagnostics & Priority Interventions

• Metrics: GFR is the best indicator of kidney function[8][13]. Creatinine is the best AKI marker[6]. Proteinuria is first sign of CKD[13].
• Hyperkalemia Emergency Care:
  • Cardioprotection: IV Calcium Gluconate (stabilizes myocardium)[14].
  • Shift K+ Intracellularly: IV Regular Insulin + Glucose, or IV Sodium Bicarbonate[14].
  • Definitive Removal: Hemodialysis or Kayexalate (avoid in paralytic ileus due to bowel necrosis)[14][15].
• Fluid Limits: Oliguric AKI: previous 24-hr loss + 600 mL[14].
• Anemia: Exogenous EPO. Monitor for hypertension, clots; supplement iron[16].

4. RRT & Post-Op Care

• HD: Rapid fluid/solute shifts. Assess AV Fistula for thrill and bruit[17]. Safety: No BP/blood draws/IVs in access arm[18]. Complication: Hypotension, cramps[19].
• PD: Uses peritoneal membrane. Core complication: Peritonitis (abdominal pain, rebound tenderness, cloudy effluent)[20][21].
• CRRT: Slow, continuous solute/fluid removal for hemodynamically unstable AKI[22][23].
• Transplantation: Post-op priority is fluid/electrolyte balance[24]. Watch for massive diuresis (replace mL-for-mL) or ATN[24]. CVD is the leading cause of death post-transplant[25].