What are the indications and usage guidelines for the Fx80 (high-flux) dialyzer in adult patients with End-Stage Renal Disease (ESRD) undergoing hemodialysis?

Fx80 Dialyzer: Indications and Usage Guidelines

Primary Indication

The Fx80 is a high-flux polysulfone dialyzer indicated for adult patients (>18 years) with End-Stage Renal Disease (ESRD) requiring intermittent hemodialysis, with either high-flux or low-flux membranes being acceptable choices based on the 2015 KDOQI guidelines. 1

Evidence-Based Recommendations

General Use in ESRD

• Biocompatible membranes (either high-flux or low-flux) are recommended for intermittent hemodialysis in adult ESRD patients. 1 The KDOQI 2015 guidelines provide a Grade 1B recommendation, indicating moderate-quality evidence supporting this approach.

• While three large randomized controlled trials (HEMO Study, MPO trial, and EGE Study) showed no overall survival benefit with high-flux versus low-flux dialyzers, meta-analysis demonstrated reduced cardiovascular mortality with high-flux membranes (HR 0.82; 95% CI 0.70-0.96). 1

Specific Patient Populations with Enhanced Benefit

The Fx80 high-flux dialyzer should be prioritized for the following subgroups where statistically significant mortality benefits have been demonstrated:

• Patients with serum albumin ≤4 g/dL: The MPO trial showed a relative risk reduction of 0.49 (95% CI 0.28-0.87) for all-cause mortality in this population. 1

• Patients with diabetes mellitus: Post-hoc analyses from both the MPO and EGE trials demonstrated improved survival with high-flux dialyzers. 1

• Patients with arteriovenous fistulas: The EGE Study showed improved cardiovascular event-free survival in this subgroup. 1

• Long-term dialysis patients (>3.7 years): The HEMO Study identified a significant interaction between flux and dialysis vintage, with lower mortality risk in patients dialyzed longer than 3.7 years. 1

β2-Microglobulin Amyloidosis Prevention

• High-flux dialyzers should be used in patients with evidence of or at risk for β2-microglobulin amyloidosis. 1 This recommendation is based on the dialyzer's enhanced middle molecule clearance capacity, which reduces β2-microglobulin accumulation that leads to dialysis-related amyloidosis affecting joints and periarticular structures.

• The Fx80 specifically demonstrates stable and effective β2-microglobulin reduction rates that correlate with increased dialyzer surface area. 2

Technical Performance Characteristics

Solute Clearance Profile

• The Fx80 provides effective clearance across multiple molecular weight ranges: urea, creatinine, and phosphate clearance are significantly influenced by blood flow (280-360 mL/min), dialysate flow (300-500 mL/min), and surface area. 2

• β2-microglobulin reduction is primarily dependent on dialyzer surface area rather than flow parameters, making the Fx80's 1.8 m² surface area a key determinant of middle molecule removal. 2

Cardiovascular Benefits

• The Fx80 high-flux dialyzer significantly improves insulin resistance (HOMA-IR, p=0.017) compared to low-flux dialyzers, suggesting potential cardiovascular protection benefits. 3 This effect occurs through improved insulin sensitivity rather than changes in inflammatory markers or oxidative stress in short-term studies.

• High-flux dialysis with the Fx80 showed reductions in cardiac mortality and composite outcomes of cardiac hospitalization or death in secondary analyses. 1

Critical Implementation Requirements

Dialysate Quality Mandates

• Ultrapure dialysate (bacteria <0.1 CFU/mL and endotoxin <0.03 IU/mL) must be used with the Fx80 high-flux dialyzer. 4 High-flux membranes allow backfiltration and backdiffusion of dialysate contaminants into patient blood, which aggravates uremia-associated inflammatory response syndrome.

• Bacteria- and endotoxin-retentive filters for online production of ultrapure dialysis fluid are required to prevent backtransport of contaminants. 4

• Dry powder cartridges for bicarbonate concentrate should be used rather than liquid concentrates to minimize bacterial contamination risk. 4

Treatment Optimization Parameters

Blood and Dialysate Flow Settings

• Effective blood flow of 280-360 mL/min demonstrates significant independent effects on small solute clearance and Kt/V. 2

• Dialysate flow of 500 mL/min is superior to 300 mL/min for optimizing urea, creatinine, and phosphate clearance due to improved dialysate distribution in the Fx80's design. 2

Treatment Duration Considerations

• The Fx80 maintains stable small solute clearance throughout the treatment session, supporting standard 4-hour treatment durations. 2

Cost-Effectiveness Considerations

• In bundled payment environments, centers must weigh the potential cardiovascular mortality benefit against increased costs. 1

• In resource-constrained settings, prioritize high-flux dialyzers like the Fx80 for the four subgroups with demonstrated mortality benefits (low albumin, diabetes, AV fistulas, long dialysis vintage) rather than universal application. 1

Common Pitfalls to Avoid

• Do not use the Fx80 or any high-flux dialyzer without ensuring ultrapure dialysate quality, as this exposes patients to inflammatory complications from bacterial contaminant backtransport. 4

• Do not expect quality-of-life improvements from high-flux versus low-flux dialysis, as the three major RCTs showed no differences in quality-of-life parameters. 1

• Do not assume albumin loss is problematic with the Fx80: studies show controlled protein loss (0.41 ± 0.21 g/session) that is significantly less than some other high-flux dialyzers. 5

• Avoid using low-flux dialyzers in patients requiring long-term maintenance hemodialysis, as high-flux dialyzers provide better cardiovascular protection over time. 3