Acute Kidney Injury and Dialysis Lecture

Vocabulary flashcards covering key terms, pathophysiology, phases, diagnostics, treatment, and dialysis concepts related to Acute Kidney Injury.

Acute Kidney Injury (AKI)

Sudden loss of kidney function marked by ↑ serum creatinine and/or ↓ urine output developing within hours to days.

Azotemia

Accumulation of nitrogenous waste products (urea, creatinine) in the blood.

Prerenal AKI

Kidney injury caused by reduced renal perfusion (e.g., hypotension, hypovolemia).

Intrarenal AKI

Damage within kidney tissue itself (e.g., ATN, interstitial nephritis, nephrotoxins).

Postrenal AKI

Impaired kidney function due to obstruction of urine outflow (e.g., stones, BPH).

Acute Tubular Necrosis (ATN)

Intrarenal injury where tubular epithelial cells slough off and clog tubules; often nephrotoxic or ischemic in origin.

Nephrotoxic Agent

Drug or substance that damages kidney tissue (e.g., aminoglycosides, contrast media).

Oliguria

Urine output < 400 mL/day; common in prerenal AKI.

Nonoliguria

AKI with normal or near-normal urine volume but impaired GFR; often seen in ATN.

Anuria

Urine output < 100 mL/day, usually indicates urinary tract obstruction.

Oliguric Phase (AKI)

First clinical phase of AKI lasting 10–14 days; features fluid overload, metabolic acidosis, hyperkalemia.

Diuretic Phase (AKI)

Phase with gradual ↑ urine output but poor concentrating ability; risk for hypovolemia, hyponatremia, hypokalemia.

Recovery Phase (AKI)

Period when GFR rises and BUN/Cr fall; renal function may improve up to 12 months.

Risk Stage (R)

AKI stage: Serum Cr ↑ 1.5× or GFR ↓ 25%; UO < 0.5 mL/kg/h × 6 h.

Injury Stage (I)

AKI stage: Serum Cr ↑ 2× or GFR ↓ 50%; UO < 0.5 mL/kg/h × 12 h.

Failure Stage (F)

AKI stage: Serum Cr ↑ 3× or > 4 mg/dL with rise ≥ 0.5 mg/dL; UO < 0.3 mL/kg/h × 24 h or anuria × 12 h.

Loss Stage (L)

Persistent complete loss of kidney function for > 4 weeks.

End-Stage (E)

Complete loss of kidney function for > 3 months.

Hyperkalemia

Serum K⁺ > 6 mEq/L; can cause fatal dysrhythmias in AKI.

Kayexalate

Sodium polystyrene sulfonate resin that exchanges Na⁺ for K⁺ in the gut to lower serum potassium.

IV Insulin with Glucose

Temporarily shifts K⁺ into cells to treat hyperkalemia.

Calcium Gluconate (IV)

Stabilizes cardiac membrane during severe hyperkalemia without lowering serum K⁺.

Ultrasound (Renal)

First-line, nephrotoxin-free imaging to rule out obstruction in AKI.

Renal Biopsy

Definitive test to confirm intrarenal causes such as ATN or glomerulonephritis.

Urinalysis Findings in ATN

Sediment with RBCs, WBCs, granular casts, protein; specific gravity fixed at 1.010.

Specific Gravity 1.010

Isosthenuria indicating tubules cannot concentrate or dilute urine (same osmolality as plasma).

Glomerular Filtration Rate (GFR)

Volume of plasma filtered per minute by the kidneys; key indicator of renal function.

Hemodialysis (HD)

Intermittent extracorporeal therapy using an artificial membrane to remove waste and fluid when GFR < 15 mL/min/1.73 m².

Peritoneal Dialysis (PD)

Dialysis using the peritoneal membrane as the semipermeable barrier; fluid removal via glucose-driven osmosis.

Continuous Renal Replacement Therapy (CRRT)

Slow, continuous extracorporeal therapy for unstable ICU patients; uses convection, diffusion, osmosis.

Semipermeable Membrane

Barrier that allows passage of certain solutes and water while preventing movement of blood cells and proteins.

Diffusion (Dialysis)

Movement of solutes from higher to lower concentration across the membrane (e.g., urea → dialysate).

Osmosis (Dialysis)

Movement of water toward higher solute concentration; glucose in dialysate pulls water from blood.

Ultrafiltration

Removal of fluid by creating a pressure gradient between blood and dialysate compartments.

Arteriovenous Fistula (AVF)

Surgical connection of an artery to a vein for HD access; best patency and lowest complication rate.

Arteriovenous Graft (AVG)

Synthetic tube connecting artery and vein; usable sooner than AVF but higher risk of infection/thrombosis.

Thrill

Palpable vibration over AVF/AVG caused by turbulent arterial blood flow; indicates patency.

Bruit

Whooshing sound heard with stethoscope over vascular access, confirming flow through fistula/graft.

Dialyzer

Cartridge with thousands of hollow fibers acting as artificial semipermeable membrane during HD.

Disequilibrium Syndrome

Cerebral edema due to rapid solute removal during HD; causes HA, N/V, seizures; treat by slowing dialysis.

Peritonitis (PD)

Infection of peritoneal cavity presenting with cloudy effluent, abdominal pain, rebound tenderness.

Contraindications to PD

Multiple abdominal surgeries, recurrent hernias, severe obesity, vertebral disease, severe COPD.

Automated Peritoneal Dialysis (APD)

Cycler-controlled PD performed at night; schedules multiple fill-dwell-drain cycles automatically.

Continuous Ambulatory Peritoneal Dialysis (CAPD)

Manual PD with ~2 L exchanges four times daily, each dwelling ~4 hours.

ACE Inhibitors in AKI

May reduce perfusion and worsen hyperkalemia; doses often lowered or stopped during AKI.