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Dialyzer and hemodialysis prescription

As described by Daugirdas, many excellent nephrologists follow an empiric model when devising the hemodialysis prescription:

  • place patients on the largest dialyzer that they can afford,
  • dialyze them for the longest amount of time that the patient will agree
  • with the highest blood flow rate that the vascular access will accommodate.

    Check the URR and/or Kt/V, and if deficient, attempt some corrective action.
    Alternatively, he suggests using basic principles of kinetic modeling while incorporating any needed adjustments to improve clearance:
  • Extending treatment time
  • Increasing dialysate flow rate
  • Increasing blood flow rate
  • Moving to a larger dialyzer.

    Studies and guidelines point to the benefits of synthetic highflux membranes, but individual patient needs should be factored into dialyzer selection.

    Along with performance parameters, it is the clinician challenge to find the optimal dialyzer based on :
  • the patient size
  • years on dialysis
  • hemodynamic status
  • tolerance to treatment time
  • tolerance to blood and dialysate flow rates
  • residual renal function
  • comorbidities
  • sufficiency of vascular access
  • immunologic and hematologic profiles
  • increased need to remove specific solutes
  • necessity of minimizing albumin losses
  • impact on quality of life if longterm complications such as dialysis-related amyloidosis can be lessened through use of a specific high performance membrane

    The priming volume of a dialyzer may also be a consideration because a low priming volume requirement allows the use of the patient own blood to prime the circuit without serious hypovolemic effects.

    In a typical adult patient this parameter may be of little consequence, but it could be important for children or small adults.

    There is an increasing demand in dialysis therapy for new measures of biocompatibility such as reducing intradialytic blood pressure variability, decreasing oxidative stress, and delaying the onset or progression of complications.

    Such selectivity based upon individual patient needs has been referred to as patient oriented dialysis which also factors in the effects of the membrane upon the patient quality of life.

    Accordingly, Sanaka recommend choosing a HPM by balancing the solute removal capacity needed for the patient with the severity of complications, which should be considered a surrogate marker for biocompatibility