Notes on AKI, CKD, Dialysis, and Kidney Transplantation

Kidney Functions

  • 1. Filters waste and excess substances such as urea, uric acid, and toxins from the blood.

  • 2. Controls how much water is excreted in the urine; regulates fluid balance.

  • 3. Regulates body’s pH by excreting acids or bases in urine; maintains acid–base balance.

  • 4. Filters electrolytes from the blood to retain or excrete them; balances electrolytes.

What Labs Do We Look At?

  • Blood Urea Nitrogen (BUN) (10-20)

  • Serum Creatinine (0.6-1.2)

  • Glomerular Filtration Rate (GFR)

  • Urinalysis

  • Electrolytes (K+, Na+, bicarbonate, etc)

  • Arterial Blood Gas (ABG)

Diagnostics

  • Ultrasonography

  • CT Scan/MRI

  • X-ray

  • MAG3 Renal Scan

Glomerulonephritis

  • What is it? Inflammation of the glomerulus

    • Proteins, WBCs, and RBCs can spill into urine

    • Can lead to nephrotic syndrome

    • Can be caused by infections, autoimmune processes, chronic illnesses, toxins, or vascular disease

  • Symptoms

    • Blood in the urine (hematuria)

    • Protein in the urine (proteinuria)

    • Edema

    • Hypertension

    • Flank pain

    • Decreased urine output

  • Complications

    • Acute Kidney Injury (AKI)

    • Chronic Kidney Disease (CKD)

    • Rapid progression may require dialysis

  • Treatment

    • Rest

    • Sodium and fluid restrictions

    • Diuretics

    • Antihypertensive medications

    • Antibiotics (if infection)

    • Dialysis if severe

Acute Kidney Injury (AKI)

  • What is AKI? Kidneys suddenly lose their ability to filter blood; waste products build up in the body.

    • Onset: few hours to days

    • Affects multiple body systems

    • Potentially reversible

    • Term often cited: Acute Kidney Injury (AKI)

  • Phases of AKI

    • 1. Initiating phase — Injury occurs; ends when symptoms start

    • 2. Oliguric phase — Very little urine produced; <400 ext{ mL/day}; swelling and electrolyte problems occur

    • 3. Diuretic phase — Lots of dilute urine; risk of dehydration and electrolyte loss

    • 4. Recovery phase — Kidney slowly heals; may take up to 1 ext{ year}

  • What causes AKI?

    • ext{Pre-renal}: Indirect damage before the kidneys

    • ext{Intra-renal}: Damage to structures inside the kidneys

    • ext{Post-renal}: Damage after the kidneys

  • AKI signs and symptoms

    • Oliguria or anuria

    • Azotemia

    • Fluid volume overload: crackles, edema (dependent or generalized), decreased oxygenation, confusion, increased respiratory rate, dyspnea

    • Hypoperfusion and hypoxemia: blood pressure around 90/40 ext{ mmHg}

  • Treatment of AKI

    • Treat the underlying cause

    • Assess fluid status: intake/output, daily weights

    • IV fluids or diuretics depending on cause

    • Avoid nephrotoxic agents

    • Nutritionist-guided diet with specified protein amounts

    • Balance electrolytes, especially potassium

    • Dialysis if indicated

Chronic Kidney Disease (CKD)

  • What is CKD? Gradual loss of kidney filtration ability; waste products build up

    • Gradual progression over months to years

    • Affects every body system

    • Progressive and irreversible

  • Major causes

    • Hypertension

    • Diabetes mellitus

    • Autoimmune disease

    • Glomerulonephritis

  • CKD signs and symptoms

    • Oliguria or anuria

    • Azotemia

    • Uremia and uremic syndrome

    • Anemia

    • Fluid volume overload: crackles, edema, decreased oxygenation, confusion, dyspnea

    • Cardiac changes

    • Bone problems (mineral and bone disease related to CKD)

    • Blood pressure often elevated (example reading shown: 180/120 ext{ mmHg})

  • Treatment of CKD

    • Lifestyle modifications: dietary changes, healthy weight, exercise, avoid smoking and alcohol

    • Control diabetes and hypertension

    • Medications: diuretics, phosphate binders, calcium and vitamin D

    • Dialysis to remove toxins and excess fluid

    • Kidney transplant when appropriate

Renal Replacement Therapy (RRT)

  • Purpose

    • Acts as the kidneys when they are not working properly

    • Removes waste and excess fluid to correct electrolyte imbalances

  • Indications

    • Symptomatic uremia

    • Hyperkalemia (increased potassium)

    • Severe metabolic acidosis

    • Fluid overload

    • Drug or alcohol intoxication

  • Forms of dialysis

    • Intermittent dialysis

    • Continuous dialysis (CRRT)

  • Dialysis modalities

    • Peritoneal Dialysis (PD): diffusion and osmosis via the peritoneal membrane

    • Types: Continuous Ambulatory PD (CAPD) and Automated PD (APD)

    • Typically completed at home

    • Processes: Fill, dwell, drain

    • Complications: Peritonitis, pain, insufficient outflow, changes in outflow

    • Hemodialysis (HD): diffusion across a semipermeable membrane

    • Intermittent HD: usually 4 ext{ hours} per session, 3 ext{ days/week}

    • Can be done at bedside or dialysis unit

    • Continuous Renal Replacement Therapy (CRRT): continuous; delivered over 24 ext{ hours}; usually in ICU

    • Uses ultrafiltration via a filter; blood passes through a filter to remove waste and fluid

  • RRT Access

    • AV fistula (native fistula)

    • AV graft (synthetic bridge)

    • Central venous catheter (CV catheter)

    • Mixed arteriovenous access configurations

    • An illustration includes: vein, artery, right atrium and connections to the dialysis machine

  • AV access complications

    • Blood clots

    • Infection

    • Aneurysms

    • Ischemia

    • Heart failure

  • HD & CRRT complications & care

    • Complications: hypotension, dialysis disequilibrium syndrome, cardiac events, reactions to dialyzers, bleeding, hypoglycemia

    • Care: monitor vital signs, daily weights, monitor for bleeding

Kidney Transplantation

  • Purpose: treats end-stage kidney disease

  • Donors: various donors available

  • Preoperative care: immunologic studies; dialysis and blood transfusion required within 24 ext{ hours} of surgery

  • Procedure: transplant kidney placed in the right or left anterior iliac fossa; ureter and renal vessels connected to the recipient; the failed native kidney is not removed

  • Postoperative care: daily weights; frequent vital signs; monitor intake and output

  • Complications: rejection, ischemia, thrombosis, renal artery stenosis, infection

Quick Reference by Modality and Topic

  • AKI phases and key thresholds

    • Initiating, Oliguric (<400 ext{ mL/day}), Diuretic, Recovery

  • Diagnostic labs for kidney function

    • BUN, Creatinine, GFR, Urinalysis, Electrolytes, ABG

  • RRT indications and modalities

    • Indications: uremia, hyperkalemia, metabolic acidosis, fluid overload, intoxication

    • PD: home-based, CAPD, APD; diffusion/osmosis; complications include peritonitis

    • HD: intermittent, short sessions; CRRT: continuous in ICU

  • Transplant considerations

    • Preop immunologic workup; perioperative management; post-op monitoring and common complications