When should dialysis be initiated in older adults with acute kidney injury (AKI) and pre-existing kidney disease, considering factors such as hyperkalemia, fluid overload, and uremic symptoms?

Early vs Late Dialysis Initiation in AKI

Dialysis in AKI should be initiated based on clinical indications (life-threatening hyperkalemia with ECG changes, refractory pulmonary edema, severe metabolic acidosis, uremic complications) rather than arbitrary laboratory thresholds or timing strategies, as there is no survival benefit to early "prophylactic" dialysis in the absence of these absolute indications. 1, 2

Absolute Indications for Emergent Dialysis

Initiate dialysis immediately when any of the following life-threatening conditions are present:

• Severe hyperkalemia with ECG changes (peaked T waves, widened QRS, loss of P waves) 2, 3, 4
• Refractory pulmonary edema unresponsive to diuretics or severe fluid overload causing respiratory compromise 2, 3, 4
• Severe metabolic acidosis with impaired respiratory compensation 2, 3
• Uremic complications including encephalopathy, pericarditis, or uremic bleeding 2, 3, 4
• Severe symptomatic dysnatremia resistant to medical management 2

These indications apply regardless of the patient's age, pre-existing kidney disease status, or absolute creatinine/BUN values. 2, 5

Evidence Against Early "Prophylactic" Dialysis

The timing debate centers on whether to initiate dialysis early (at higher GFR or lower BUN) versus waiting for absolute indications:

• No survival advantage exists for early dialysis initiation based solely on GFR thresholds when corrected for lead-time bias 1
• Observational data showing worse outcomes with delayed dialysis (higher BUN at initiation) likely reflects residual confounding by severity of illness—sicker patients both delay dialysis longer AND have worse outcomes independent of timing 1, 6
• Patients with more comorbidities tend to start dialysis at higher GFRs, but this practice pattern does not improve their outcomes 1
• Dialysis itself carries risks including hypotension that may accelerate loss of residual kidney function, access-related complications, and dialysate-related issues 1

Symptom-Based Approach (KDIGO Guideline Framework)

Initiate dialysis when one or more of the following are present, which typically but not invariably occurs at GFR 5-10 mL/min/1.73 m² in chronic kidney disease (this framework applies to AKI with modifications): 1

• Symptoms or signs attributable to kidney failure (serositis, pruritus) 1
• Acid-base or electrolyte abnormalities (beyond the absolute indications above) 1
• Inability to control volume status or blood pressure 1
• Progressive deterioration in nutritional status refractory to dietary intervention 1
• Cognitive impairment attributable to uremia 1

Critical caveat for older adults with AKI: The interpretation of symptoms must account for the fact that uremic symptoms are nonspecific and may overlap with symptoms from comorbidities. 1 Do not initiate dialysis for symptoms that may be unrelated to kidney failure, as dialysis will not improve outcomes in such cases. 1

Special Considerations for Older Adults with Pre-existing CKD

For the specific population in your question (older adults with AKI and pre-existing kidney disease):

• Hyperkalemia management: If potassium is rising but ECG remains normal, attempt medical management first (insulin/glucose, beta-agonists, sodium bicarbonate if acidotic, potassium binders). 7 Only initiate dialysis if ECG changes develop or medical management fails. 2, 3

• Fluid overload: Attempt diuretic therapy first (furosemide, potentially high-dose or continuous infusion). 4 Only initiate dialysis if pulmonary edema persists despite aggressive diuresis or if respiratory compromise develops. 2, 3

• Uremic symptoms: Ensure symptoms are truly uremic rather than related to comorbidities before initiating dialysis. 1 Common uremic symptoms include altered mental status (in absence of other causes), pericardial friction rub, or uremic bleeding. 2, 4

Modality Selection

Once the decision to initiate dialysis is made:

• Intermittent hemodialysis is preferred for hemodynamically stable patients requiring rapid correction of severe hyperkalemia (faster potassium clearance) 2, 3, 5

• Continuous renal replacement therapy (CRRT) is indicated for: 2, 3, 5

  • Hemodynamically unstable patients requiring vasopressor support
  • Patients with acute brain injury or increased intracranial pressure (provides more stable hemodynamics and better ICP control)
  • Severe fluid overload in unstable patients (allows gentler fluid removal)

• CRRT dosing: Deliver effluent volume of 20-25 mL/kg/h 2, 3, 5

• Intermittent HD dosing: Target Kt/V of 3.9 per week 2, 3

• Use bicarbonate-based dialysate/replacement fluids rather than lactate, especially in shock, liver failure, or lactic acidemia 2, 3, 5

Common Pitfalls to Avoid

1. Do not initiate dialysis based solely on creatinine or BUN thresholds without clinical indications, as this exposes patients to dialysis risks without proven benefit. 1, 5

2. Do not assume normal creatinine during dialysis indicates kidney recovery—creatinine is artificially lowered by dialysis, not by renal recovery. 5 True recovery requires sustained independence from dialysis for ≥14 days. 1, 5

3. Avoid excessive fluid removal and hypotension during dialysis, as this can cause re-injury to recovering kidneys and reduce likelihood of dialysis independence. 5, 8

4. Do not delay dialysis once absolute indications are present—severe hyperkalemia with ECG changes, refractory pulmonary edema, and uremic pericarditis require immediate intervention. 2, 3, 4

Post-Dialysis Follow-up

For patients who recover from AKI requiring dialysis:

• Assess kidney function within 3 days (no later than 7 days) after last dialysis session 1
• Define recovery as sustained independence from dialysis for minimum 14 days 1, 5
• For patients discharged on dialysis, perform weekly pre-dialysis creatinine measurements and regular 24-hour urine collections to assess residual kidney function 1, 5
• Ensure nephrology follow-up within 3 months to assess for new-onset or worsening CKD 1