Abstract: SA-PO668

Volume of Urea Cleared as a Therapy Dosing Guide for More Frequent Hemodialysis

Session Information

Category: Dialysis

  • 604 Home and Frequent Dialysis

Authors

  • Leypoldt, J. Ken, None, San Clemente, California, United States
  • Collins, Allan J., Chronic Disease Research Group, Minneapolis, Minnesota, United States
Background

Prescribing more frequent hemodialysis (HD) based on conventional thrice weekly HD therapy normalized to a weekly dose is challenging. Urea kinetic modeling based on the normalized urea distribution volume (V) has been shown to be suboptimal for smaller and female patients. Alternatively, prescribing the volume of urea cleared (Kt) to patient body surface area (BSA) has recently been shown to be promising (Maduell et al, Kidney Int 2016; Sridharan et al, Am J Kidney Dis 2017). Prescribing more frequent HD (5 or 6 times-per-week) to BSA has not been adequately explored.

Methods

We compared modeled Kt to the nearest L required to achieve a minimal dose of therapy based on BSA as defined by Lowrie et al (Kidney Int 2005) with that recommended by KDOQI Clinical Practice Guideline for Hemodialysis Adequacy Update based on patient V, i.e. weekly stdKt/V=2.1 (NKF, Am J Kidney Dis 2015). Estimates of Kt were calculated for conventional, thrice weekly HD (treatment time=240 min) and 5 and 6 times-per-week HD (treatment times=180 min). Results were compared for patients with different anthropometric estimates of total body water (Vw). BSA was assumed proportional to V to the power of 0.7, and residual kidney function was assumed negligible.

Results

Modeled Kt (L) for the therapies are tabulated. As during conventional thrice weekly HD, minimal Kt for more frequent HD based on BSA is higher for patients with small Vw and lower for patients with large Vw than based on weekly stdKt/V=2.1. Simple Kt prescriptions for 5 times-a-week HD based on the principles from Lowrie et al in L are equal to 20+0.4×(Vw-35). For 6 times-a-week HD, Kt prescriptions in L are equal to 16+0.3×(Vw-35). Such prescriptions require careful consideration of dialyzer type, blood flow rate, and dialysate flow rate (or total dialysate volume).

Conclusion

Prescribing more frequent HD based on BSA as extrapolated from Lowrie et al suggests the minimal dose of Kt is higher for small patients and lower for large patients than based on a weekly stdKt/V=2.1. Other aspects of dialysis adequacy require additional consideration.

Modeled Kt (L) versus Patient Vw (L)
 3 Times-per-week HD5 Times-per-week HD6 Times-per-week HD
Patient Vw (L)Lowrie et alKDOQILowrie et alKDOQILowrie et alKDOQI
25383416141311
35454720201616
45516124261920
55557427312125

Funding

  • Commercial Support