What are the indications for hemodialysis in patients with Acute Kidney Injury (AKI)?

Indications for Hemodialysis in Acute Kidney Injury

Initiate hemodialysis immediately in AKI when life-threatening changes in fluid, electrolyte, and acid-base balance exist, specifically: severe hyperkalemia with ECG changes, severe metabolic acidosis with impaired compensation, pulmonary edema unresponsive to diuretics, uremic complications (encephalopathy, pericarditis, bleeding), or severe fluid overload causing respiratory compromise. 1

Absolute (Emergent) Indications

These require immediate dialysis initiation regardless of other clinical parameters:

Electrolyte Emergencies

• Severe hyperkalemia or rapidly rising potassium levels, particularly when accompanied by ECG changes (peaked T waves, widened QRS, loss of P waves) 1, 2
• Severe dysnatremia that is symptomatic or resistant to medical management 1

Acid-Base Disturbances

• Severe metabolic acidosis with impaired respiratory compensation 1, 2
• Lactic acidemia that is severe and refractory to medical management 1

Volume Overload

• Pulmonary edema unresponsive to diuretics 1, 2
• Severe fluid overload causing respiratory compromise, especially with anuria or oliguria and progressive volume accumulation 1, 2

Uremic Complications

• Uremic encephalopathy (altered mental status, asterixis, seizures) 1, 2
• Uremic pericarditis (pericardial friction rub, chest pain) 1, 2
• Uremic bleeding (platelet dysfunction, coagulopathy) 1, 2

Relative Indications

These warrant strong consideration for dialysis initiation:

• Rapidly rising BUN and creatinine levels in the setting of oliguria or anuria 1
• Rhabdomyolysis with progressive AKI and myoglobinuria, particularly in crush injury where earlier initiation may improve survival 3, 1

Modality Selection Algorithm

For Hemodynamically Stable Patients:

• Use intermittent hemodialysis for rapid correction of severe hyperkalemia due to faster potassium clearance 1, 2
• Deliver a Kt/V of 3.9 per week 3, 2

For Hemodynamically Unstable Patients:

• Use CRRT rather than standard intermittent hemodialysis for patients requiring vasopressor support 3, 1, 4
• CRRT provides gentler fluid removal, more stable hemodynamics, and better tolerance of volume shifts 1, 4
• Deliver an effluent volume of 20-25 mL/kg/h 3, 2

For Patients with Neurological Complications:

• Use CRRT rather than intermittent hemodialysis for patients with acute brain injury, increased intracranial pressure, or generalized brain edema 3, 1
• CRRT provides more stable control of intracranial pressure and avoids rapid osmotic shifts 1

Special Populations:

• Crush injury/trauma-associated AKI: Consider earlier initiation as it may improve survival; often requires multiple treatments daily for hyperkalemia control 3, 1
• Pediatric patients: Peritoneal dialysis may be considered when other options unavailable, though rapid exchanges required for efficient potassium removal 3, 1

Technical Implementation

Vascular Access:

• Use uncuffed nontunneled dialysis catheters for initial access in emergent situations 3, 2
• Obtain ultrasound guidance for catheter insertion 3
• Obtain chest radiograph promptly after placement and before first use of internal jugular or subclavian catheters 3

Dialysate Composition:

• Use bicarbonate rather than lactate as buffer in all AKI patients 3, 1
• This is particularly critical in patients with circulatory shock, liver failure, or lactic acidemia 3, 4

Anticoagulation Strategy:

• Use regional citrate anticoagulation for CRRT in patients without contraindications 3, 2
• For intermittent hemodialysis, use unfractionated or low-molecular-weight heparin 3
• Use minimal or no anticoagulation in trauma or bleeding-prone patients 3, 2

Critical Pitfalls to Avoid

• Do not delay dialysis initiation when absolute indications exist while waiting for hemodynamic optimization—this increases mortality 4
• Do not use standard intermittent hemodialysis in hemodynamically unstable patients, as rapid fluid shifts can precipitate cardiovascular collapse or cardiac ischemia 4
• Do not rely solely on BUN or creatinine levels to determine timing—focus on life-threatening complications 1
• Do not underdose dialysis: Frequently assess actual delivered dose and adjust prescription accordingly 3