Outside-In Hemofiltration for Prolonged Operation without Clogging

Area of Science:

• Biomedical Engineering
• Nephrology
• Fluid Dynamics

Background:

• Continuous renal replacement therapy (CRRT) relies on hemofiltration (HF), but its long-term application is hindered by filter thrombosis and clogging.
• Current HF systems typically have a maximum filter lifespan of less than 20 hours, necessitating frequent replacements.

Purpose of the Study:

• To investigate the efficacy of outside-in hemofiltration (OIH) in achieving prolonged and consistent filter performance.
• To analyze the impact of thrombus deposition on fluid flow and filtrate flux in the OIH system.

Main Methods:

• Implementation of an outside-in hemofiltration setup with blood flowing into the inter-fiber space (IFS).
• Microscopic examination of fiber bundle sections to assess thrombus morphology and distribution.
• Development of a mathematical model to quantify the effect of thrombus deposition on hydrodynamic flow.

Main Results:

• Achieved continuous hemofiltration for over 100 hours, a significant improvement over conventional methods.
• Observed that thrombi in the IFS have minimal impact on blood flow and filtrate flux due to interconnected flow channels.
• Demonstrated that thrombus dimensions are limited by inter-fiber gaps, preventing widespread clogging.

Conclusions:

• Outside-in hemofiltration offers a promising solution for extending the lifespan of hemofiltration filters in renal replacement therapy.
• The unique hydrodynamic properties of the IFS mitigate the negative effects of thrombus formation.
• Further research into anticoagulant concentration is needed to optimize OIH performance, especially in cases of blood instability.