Ultrafiltration (UF) Profiles in Dialysis
UF profiling is a dialysis technique that varies the rate of fluid removal throughout the treatment session, typically using a linearly or stepwise decreasing pattern, designed to improve hemodynamic tolerance by allowing better vascular refilling—though evidence for clinical benefit remains mixed. 1
Definition and Technical Approach
UF profiling modulates the ultrafiltration rate during hemodialysis rather than maintaining a constant rate throughout the session. 2 The technique aims to improve vascular compensation and tolerance of fluid removal by adjusting the hourly UF rate according to predetermined patterns. 1
Common UF Profile Patterns
Linear decreasing profile (UF profile 1): Continuously declining UF rate from start to finish of dialysis, which showed reduced incidence of hypotension (5.7% vs 10.6% with constant UF) in one study. 2
Stepwise decreasing profile (UF profile 2): UF rate decreases in discrete steps during the treatment session. 2
Intermittent high-pulse profiles (UF profiles 3-5): High UF rates interrupted by UF pauses—these profiles markedly increased hypotensive episodes (18.4%) and cannot be recommended. 2
Constant UF rate (UF profile 0): Traditional approach with no variation, serving as the control comparison. 2
Evidence for Clinical Outcomes
Intradialytic Hypotension
The evidence for UF profiling reducing intradialytic hypotension is contradictory and generally disappointing. 3, 2, 4
A 2012 study found that sodium and UF profiles (linearly decreasing) failed to reduce the incidence of intradialytic hypotension compared to constant rates, and actually increased symptomatic hypotensive episodes and pre-dialysis systolic blood pressure. 3
A 2021 randomized crossover trial showed no significant difference in intradialytic hypotension between UF profiling and conventional UF. 4
However, the 2000 study demonstrated that linear decreasing UF profiles reduced hypotension incidence to 5.7% compared to 10.6% with constant UF. 2
Patient Symptoms and Quality of Life
UF profiling significantly reduced the odds of light-headedness compared to conventional UF. 4
Isolated sodium profile (without UF profiling) was associated with more malaise and less achievement of target session duration. 3
Volume Status and Hemodynamics
UF profiling resulted in significantly lower plasma refill (better post-dialysis volume status) compared to conventional UF. 4
Vascular refilling strongly correlates with UF volume (r² 0.877) and pre-dialysis volume overload (r² 0.617), with mean refilling fraction of 75.75%. 5
No significant difference was found in troponin T changes or left ventricular global longitudinal strain between UF profiling and conventional UF. 4
Critical Relationship: UF Rate and Mortality
Higher UF rates, even as low as 6 ml/h/kg, are associated with higher mortality risk and end-organ ischemia (heart, brain, liver, gut, kidneys). 1 This relationship is independent of the profiling pattern used. 1
High UFR-induced intradialytic hypotension predicts cardiac remodeling in long-term follow-up, with decreased ejection fraction, larger left atrial diameter index, and increased left ventricular mass index observed over 5 years. 6
The interaction between UFR and intradialytic hypotension is notably associated with left ventricular mass index variation (OR = 1.37). 6
Clinical Application Algorithm
Prioritize lowering the absolute UF rate before implementing UF profiling. 1, 7
First-line strategy: Lower UF rates by increasing dialysis treatment time and/or decreasing interdialytic weight gain—this is more important than the profiling pattern. 1
If UF profiling is attempted: Use a linearly decreasing profile rather than intermittent high-pulse patterns, which worsen hypotension. 2
Avoid combining with sodium profiling unless specifically indicated, as isolated sodium profiling may increase symptomatic hypotension and pre-dialysis blood pressure. 3
Consider relative blood volume (RBV) monitoring to identify the subgroup of patients (approximately 60% of hypotension-prone patients) who have hypovolemia-induced hypotension and may benefit from individualized UF rate adjustments based on RBV thresholds. 2
For patients on beta-blockers: Expect significantly lower vascular refilling rates, which may necessitate more conservative UF approaches. 5
Common Pitfalls
Do not use intermittent high-pulse UF profiles—these dramatically increase hypotensive episodes. 2
Do not rely on UF profiling alone to manage intradialytic hypotension; cardiovascular status optimization, target-weight reassessment, and absolute UF rate reduction remain more important. 1, 7
Do not assume all hypotension-prone patients will benefit—approximately 40% have hypotension unrelated to hypovolemia and will not respond to UF profiling. 2
Do not overlook the delivered dialysis dose—UF profiling does not improve achievement of target dialysis adequacy. 3