Are laboratory profiles helpful during dialysis?

Intradialytic Profiling Strategies: Limited Evidence for Routine Use

The evidence does not support routine use of intradialytic profiling (sodium, temperature, or ultrafiltration) for most dialysis patients, as these techniques have shown minimal benefit and potential harm in recent high-quality studies. 1

Blood Volume Monitoring: Potentially Harmful

• The randomized CLIMB trial demonstrated that intradialytic blood volume monitoring was associated with higher mortality and hospitalization rates compared to conventional clinical monitoring, making routine use inadvisable 1
• Blood volume monitoring has conflicting evidence regarding prediction of intradialytic hypotension, though it may have prognostic value in select cases 1
• In pediatric patients, relative blood volume-guided ultrafiltration algorithms may improve blood pressure control, though randomized trial data are lacking 1

Sodium Profiling: Use With Extreme Caution

• Data from the Dialysis Outcomes and Practice Patterns Study (DOPPS) indicate that routine sodium profiling to prevent intradialytic hypotension is associated with increased all-cause mortality, making it unsuitable for routine use 1
• Sodium profiling must be used judiciously as it results in sodium loading, hypervolemia, increased thirst, and greater interdialytic weight gain 1
• One meta-analysis suggests stepwise (versus linear) sodium profiling provides marginally better hemodynamic stability when profiling is deemed necessary 1
• High dialysate sodium concentrations (≥140 mEq/L) should be avoided as they aggravate thirst, fluid gain, hypertension, and cardiovascular workload 2

Temperature Biofeedback: Modest Benefit

• Cooling dialysate temperature to 0.5°C below body temperature is well-tolerated and associated with hemodynamic stability 1
• Isothermic hemodialysis (maintaining predialysis body temperature) reduced intradialytic morbid events by 25% compared to standard approaches in hypotension-prone patients 1
• The MY TEMP trial (NCT02628366) is evaluating whether dialysate cooling affects cardiovascular events, but results are pending 1

Ultrafiltration Profiling: Insufficient Evidence

• Randomized controlled trial data on ultrafiltration profiling independent of blood volume monitoring and sodium profiling are scarce 1
• A crossover RCT published in 2000 demonstrated no benefit from UF profiling 1
• Isolated ultrafiltration is commonly used but currently has limited evidence supporting this approach 1

Dialysate Calcium: Requires Careful Consideration

• Dialysate calcium of 2.5 mEq/L is associated with decreased left ventricular contractility, corresponding blood pressure decreases, and significant intradialytic hypotension in cardiac-compromised patients 1
• Dialysate calcium of 3.5 mEq/L may lead to hypercalcemia and decreased bone turnover 1
• Dialysate calcium of 3.0 mEq/L shows only marginal benefit for preventing intradialytic hypotension episodes 1

Bioimpedance: Investigational Only

• A small study of 15 patients suggests bioimpedance may assess the relationship between plasma refilling and tissue hydration during dialysis 1
• Current evidence is insufficient to justify routine use of bioimpedance for intradialytic volume management 1

Alternative Approaches With Better Evidence

• Hemodiafiltration demonstrates significant reduction in intradialytic hypotension compared to regular hemodialysis in an RCT of 146 patients, with better hemodynamic stability at higher convection volumes 1
• Midodrine (5 mg administered 30 minutes before dialysis) improves intradialytic and postdialytic blood pressures by maintaining central blood volume and cardiac output 1

Clinical Examination Remains the Mainstay

• In resource-constrained environments, clinical examination (blood pressure, edema, jugular venous pressure, lung examination) remains the primary method for volume assessment 1
• Signs and symptoms of volume status include breathlessness, orthopnea, edema, elevated jugular venous pressure, cardiomegaly, lung congestion, light-headedness, cramps, and weight changes 1

Common Pitfalls to Avoid

• Do not implement routine blood volume monitoring based on older literature—the CLIMB trial showed harm 1
• Avoid routine sodium profiling given the DOPPS mortality data; reserve for highly selected cases only 1
• Do not use high dialysate sodium (≥140 mEq/L) as it worsens volume overload and hypertension 2
• Recognize that poor temporal correlation exists between blood volume decrease and onset of intradialytic hypotension 1