From the Guidelines
Hemodialysis and hemofiltration are distinct renal replacement therapies, with hemodialysis primarily using diffusion and hemofiltration relying on convection to remove waste products and excess fluid from the blood, and the choice between them depends on the patient's clinical condition, hemodynamic stability, and specific clearance needs. The key difference between hemodialysis and hemofiltration lies in their operating principles, with hemodialysis utilizing diffusion to remove small molecules like urea and creatinine, and hemofiltration using convection to clear middle-sized molecules like inflammatory cytokines 1. Some of the main advantages of each method include:
- Hemodialysis: more effective at removing small molecules, typically requires intermittent sessions (usually three times weekly for 3-4 hours) 1
- Hemofiltration: better clears middle-sized molecules, often used continuously in critically ill patients as Continuous Renal Replacement Therapy (CRRT) 1 In clinical practice, these methods are often combined as hemodiafiltration to maximize the benefits of both techniques, especially in patients with hypotension or those requiring more prolonged treatment sessions 1. The choice between hemodialysis and hemofiltration should be guided by the patient's specific needs, including their hemodynamic stability, with more prolonged modalities like Continuous Kidney Replacement Therapy (CKRT) or Prolonged Intermittent Kidney Replacement (PIKRT) preferred in critically ill patients due to their better hemodynamic stability and tolerance of fluid removal 1.
From the Research
Differences between Hemodialysis and Hemofiltration
- Hemodialysis is a process that uses a dialyzer to filter waste products from the blood, relying on diffusion to remove solutes 2.
- Hemofiltration, on the other hand, uses convection to remove waste products from the blood, where water and solutes are forced through a semipermeable membrane 3.
- Hemodiafiltration combines both dialysis and hemofiltration, offering enhanced solute clearance and improved patient-centered outcomes 2.
Key Characteristics
- Hemodialysis is typically performed at a dialysis center through vascular access via an arteriovenous fistula, an arteriovenous graft, or a central venous catheter 4.
- Hemofiltration can be performed continuously, such as continuous venovenous hemofiltration, which is commonly used for critically ill patients with acute kidney injury 3.
- The choice of renal replacement therapy modality should be guided by the individual patient's clinical status, medical and nursing expertise, and availability of the modality 5.
Clinical Outcomes
- High-volume hemodiafiltration has been found to offer enhanced solute clearance, improved inflammatory marker profiles, and better patient-centered outcomes compared to high-flux hemodialysis 2.
- Randomized studies have found that high-volume hemodiafiltration demonstrates superior outcomes, with a 23% improvement in survival rates when achieving convective volumes ≥23 L/session 2.
- There is no significant difference in long-term mortality rates between peritoneal dialysis and hemodialysis 4.