Does intermittent hemodialysis (HD) during Acute Kidney Injury (AKI) decrease the chance of renal function recovery?

Impact of Intermittent Hemodialysis on Renal Function Recovery in Acute Kidney Injury

The selection of renal replacement therapy (RRT) modality, including intermittent hemodialysis, does not appear to have a major impact on recovery of kidney function in patients with acute kidney injury (AKI). 1

Evidence on RRT Modality and Renal Recovery

The 2020 Kidney Disease: Improving Global Outcomes (KDIGO) conference on controversies in AKI specifically addressed this question and concluded that:

• The choice of RRT modality does not significantly influence the likelihood of kidney function recovery 1
• Selection of RRT modality should be based on patient characteristics, local resources, and expertise of personnel rather than concerns about renal recovery 1

Continuous vs. Intermittent RRT

While there are theoretical concerns about intermittent hemodialysis (IHD) potentially affecting renal recovery due to hemodynamic instability, the evidence does not support this:

• In hemodynamically unstable patients, continuous RRT is more physiologically appropriate than intermittent hemodialysis 1
• However, randomized controlled trials have not demonstrated better outcomes with continuous RRT in terms of renal recovery 1
• Recent secondary analysis of the AKIKI and IDEAL-ICU studies even suggested that continuous RRT might be associated with less favorable outcomes compared to IHD in patients with lesser severity of disease 2

Considerations for RRT Modality Selection

The decision between intermittent hemodialysis and continuous RRT should be guided by:

1. Hemodynamic status:

   • Continuous RRT is preferred for hemodynamically unstable patients 1
   • IHD can lead to greater hemodynamic instability due to rapid fluid shifts 1

2. Intracranial pressure concerns:

   • Both continuous and intermittent RRT can lead to changes in intracranial pressure
   • The risk is higher with intermittent RRT 1

3. Resource availability:

   • Selection should consider available resources and expertise of personnel 1
   • In resource-limited settings, intermittent hemodialysis may be more practical 3

4. Patient-specific factors:

   • Severity of illness
   • Fluid overload status
   • Metabolic derangements

Optimizing Intermittent Hemodialysis to Promote Renal Recovery

If intermittent hemodialysis is selected, these strategies may help optimize the potential for renal recovery:

• Adequate dosing: Deliver a Kt/V of at least 1.2 per treatment three times a week 1
• Hemodynamic optimization: Use cooling of dialysate and raising dialysate sodium concentration to mitigate hemodynamic instability 3
• Avoid nephrotoxins: Discontinue nephrotoxic medications that may impair renal recovery 4
• Volume management: Careful assessment of fluid status and appropriate ultrafiltration goals 1

Transitioning Between Modalities

The KDIGO guidelines recommend:

• Transition from continuous RRT to intermittent hemodialysis should be considered when:
  • Vasopressor support has been stopped
  • Intracranial hypertension has resolved
  • Positive fluid balance can be controlled by intermittent hemodialysis 1

Discontinuation of RRT

Discontinuation of RRT should be considered when:

• Kidney function has recovered sufficiently
• RRT becomes inconsistent with shared care goals 1
• Increasing urine output is a positive prognostic sign for successful discontinuation 5

Common Pitfalls to Avoid

1. Delaying nephrology consultation: Early nephrology involvement may help optimize management and potentially avoid unnecessary RRT 4

2. Continuing nephrotoxic medications: ACE inhibitors, ARBs, and other nephrotoxic drugs should be discontinued when AKI is diagnosed 4

3. Inadequate volume management: For pre-renal AKI due to hypovolemia, prompt fluid resuscitation is essential 4

4. Inappropriate electrolyte management: Hyperkalemia requiring dialysis may be preventable with proper medication management and dietary restrictions 4

In conclusion, while the choice between intermittent hemodialysis and continuous RRT should be tailored to the individual patient's clinical status, the current evidence suggests that the modality choice itself does not significantly impact the likelihood of renal recovery in AKI patients.