10.3 Acute Kidney Injury, Chronic Kidney Disease & Dialysis Nursing

10.3 Acute Kidney Injury, Chronic Kidney Disease & Dialysis Nursing

Acute Kidney Injury (AKI) Management

Acute Kidney Injury (AKI) is characterized by a rapid decline in renal excretory function, leading to the accumulation of nitrogenous waste products (urea and creatinine) and dysregulation of fluid, electrolyte, and acid-base homeostasis. In Singapore public hospitals, AKI diagnosis and staging follow the international KDIGO (Kidney Disease: Improving Global Outcomes) guidelines.

KDIGO Definition & Staging Criteria

AKI is defined by any one of the following:

• Increase in serum creatinine by ≥ 26.5 μmol/L within 48 hours; OR
• Increase in serum creatinine to ≥ 1.5 times baseline within the prior 7 days; OR
• Urine output < 0.5 mL/kg/hour for 6 consecutive hours.

Etiologic Classification & Clinical Recognition

1. Prerenal AKI (Hypoperfusion): Resulting from decreased renal blood flow without parenchymal tissue damage. Causes include hypovolemia (hemorrhage, severe dehydration, diarrhea), acute heart failure, systemic sepsis, and drugs impairing autoregulation (ACE inhibitors, ARBs, NSAIDs). Prerenal AKI is reversible if cardiac output and renal perfusion are restored promptly.
2. Intrinsic (Intrarenal) AKI: Resulting from direct structural damage to the glomeruli, tubules, or interstitium. The most common cause is Acute Tubular Necrosis (ATN), secondary to prolonged renal ischemia or nephrotoxic agents (aminoglycosides like gentamicin, radiocontrast media, vancomycin, NSAIDs).
3. Postrenal AKI (Obstruction): Resulting from anatomical obstruction of urinary flow anywhere from the renal pelvis to the urethral meatus. Causes include benign prostatic hyperplasia (BPH), neurogenic bladder, bilateral ureteral calculi, and pelvic malignancies.

Priority Nursing Interventions in AKI

• Strict Fluid Balance Monitoring: Maintain an hourly intake and output chart. In oliguric phase AKI, calculate daily fluid restriction as: 500 mL (insensible loss) + total urine output from previous 24 hours.
• Nephrotoxic Agent Avoidance: Review medication charts daily. Withhold NSAIDs, aminoglycosides, and ACE inhibitors in deteriorating renal function.
• Prevention of Contrast-Induced Acute Kidney Injury (CI-AKI): For patients undergoing contrast CT scans, ensure pre- and post-procedure hydration with IV 0.9% Normal Saline per MOH nephrology protocols. Withhold metformin for 48 hours post-contrast administration to prevent fatal lactic acidosis.

Chronic Kidney Disease (CKD) & Uremic Complication Nursing

Chronic Kidney Disease (CKD) involves progressive, irreversible destruction of nephrons lasting > 3 months. CKD is classified into Stages G1 to G5 based on Estimated Glomerular Filtration Rate (eGFR), with Stage G5 (eGFR < 15 mL/min/1.73m²) defining End-Stage Renal Disease (ESRD) requiring renal replacement therapy (dialysis or kidney transplantation).

Management of Uremic Manifestations & Electrolyte Derangements

• Fluid Overload & Cardiovascular Risks: Patients with CKD experience sodium and water retention leading to hypertension, peripheral edema, and acute pulmonary edema (presenting with pink frothy sputum, severe orthopnea, and bilateral crackles). Nursing care mandates daily weight measurement (using the same scale at the same time), strict fluid restriction, and loop diuretic administration (e.g., IV furosemide).
• Renal Anemia: Decreased functional renal parenchyma leads to deficient production of erythropoietin (EPO). Management involves administering Erythropoietin-Stimulating Agents (ESAs, e.g., Epoetin alfa, Darbepoetin alfa) subcutaneously alongside IV iron sucrose supplementation. Target hemoglobin levels are maintained between 10.0 and 11.5 g/dL; over-correction (> 12.0 g/dL) increases thromboembolic and cardiovascular risk.
• Hyperphosphatemia & Secondary Hyperparathyroidism: Failing kidneys cannot excrete phosphate, leading to hyperphosphatemia (> 1.45 mmol/L) and hypocalcemia. Administer phosphate binders (e.g., calcium carbonate, sevelamer) strictly with meals to bind dietary phosphate in the gut lumen.

Emergency Nursing Management of Severe Hyperkalemia

Hyperkalemia (serum potassium > 5.5 mmol/L, with severe life-threatening elevation at > 6.5 mmol/L) is a medical emergency in renal failure. ECG changes progress from tall peaked T waves to prolonged PR interval, widening of QRS complex, sine-wave pattern, and ventricular fibrillation/cardiac arrest.

1. Immediate Stabilization: Administer IV Calcium Gluconate 10% (10 mL IV over 2–5 minutes) to stabilize myocardial cell membranes and prevent fatal arrhythmias. Calcium gluconate does not lower serum potassium levels; it antagonizes hyperkalemic cardiac membrane excitability.
2. Intracellular Shift of Potassium:
   • Administer IV Regular Insulin (10 units) combined with 50 mL of Dextrose 50% (D50W) IV push. Insulin drives potassium into cells, while dextrose prevents hypoglycemia.
   • Administer Nebulized Salbutamol (10–20 mg) to further promote intracellular potassium shifting.
   • Administer IV Sodium Bicarbonate if severe metabolic acidosis is present.
3. Potassium Elimination:
   • Administer potassium-binding resins (e.g., Sodium Polystyrene Sulfonate / Kalimate, or Patiromer) orally or rectally.
   • Initiate emergency Hemodialysis if conservative measures fail or in severe acute pulmonary edema.

Dialysis Nursing: Hemodialysis (HD) & Peritoneal Dialysis (PD)

When renal function deteriorates to ESRD, renal replacement therapy becomes mandatory for survival.

Hemodialysis (HD) & Vascular Access Care

Hemodialysis removes uremic toxins and excess fluid across a semipermeable membrane in an external dialyzer. Vascular access is established via an Arteriovenous Fistula (AVF) (surgical anastomosis of an artery to a vein, typically radial-cephalic), Arteriovenous Graft (AVG) (synthetic conduit), or a central venous HD catheter (Permcath).

• AVF Assessment Standards: Every shift, the nurse must assess the AV access for patency:
  • Thrill: Palpate over the anastomosis site for a continuous soft vibration or buzzing sensation.
  • Bruit: Auscultate with a stethoscope over the fistula for a continuous low-pitched machinery murmur.
  • Absence of a thrill or bruit indicates access thrombosis, requiring emergency vascular surgical notification.
• Vascular Access Limb Protection ("Save the Limb"):
  • Never perform blood pressure measurements, IV cannulations, venipunctures, or arterial punctures on the extremity with an AV fistula or graft.
  • Place a bright pink or red alert band on the affected limb and display a "No BP / No Venipuncture" sign above the patient's bed.
  • Educate the patient to avoid wearing tight clothing, jewelry, or carrying heavy bags on the access arm, and avoid sleeping on that arm.
• Complications: Monitor for Dialysis Disequilibrium Syndrome (DDS) during initial HD sessions. DDS is caused by rapid solute (urea) removal from the intravascular space while brain urea concentration remains high, drawing water into brain tissue causing cerebral edema (headache, confusion, twitching, seizures). Treatment involves slowing blood flow rates and administering hypertonic saline or mannitol.

Peritoneal Dialysis (PD) & Infection Control

Peritoneal dialysis utilizes the patient's peritoneal membrane as a semipermeable membrane. Dialysate fluid containing high dextrose concentrations (1.5%, 2.5%, or 4.25%) is instilled into the peritoneal cavity via a Tenckhoff catheter, left for a dwell time, and drained out. Modalities include Continuous Ambulatory Peritoneal Dialysis (CAPD) and Automated Peritoneal Dialysis (APD).

• Strict Aseptic Technique: PD connections and exchanges must be performed using sterile non-touch technique in a clean environment (closing windows, turning off fans/air conditioners, wearing surgical masks) to prevent microbial introduction into the peritoneal cavity.
• Peritonitis Prevention & Detection: Peritonitis is the most frequent and serious complication of PD.
  • Hallmark Clinical Sign: Cloudy peritoneal dialysate effluent. Additional signs include diffuse abdominal pain, rebound tenderness, fever, nausea, and vomiting.
  • Nursing Action: Upon observing cloudy effluent, the nurse must immediately collect a sample of the drained effluent bag for cell count, Gram stain, and bacterial culture. A diagnostic effluent WBC count is > 100 cells/μL with > 50% polymorphonuclear (PMN) neutrophils. Intraperitoneal antibiotics (e.g., cephalosporins or vancomycin added directly to dialysate bags) are initiated per nephrology protocol.
• Exit-Site Care: Inspect the catheter exit site daily for erythema, purulent drainage, tenderness, or cuff erosion. Perform daily exit-site cleaning using chlorhexidine and secure the catheter to prevent mechanical traction.

Clinical Summary Table: Hemodialysis vs. Peritoneal Dialysis