Online conductivity monitoring of dialysis adequacy versus Kt/V derived from urea reduction ratio: A prospective study from a Saudi center
Khalid Al Saran1, Alaa Sabry2, Mamdouh Abdulghafour1, Ahmed Yehia1
1Prince Salman Center for Kidney Disease, Riyadh, Kingdom of Saudi Arabia; 2Mansoura Urology and Nephrology Center, Mansoura University, Mansoura, Egypt
Introduction: Ad equate delivered dose of solute removal (as assessed by urea reduction and calculation of Kt/V) is an important determinant of clinical outcome in chronic hemodialysis (HD) patients. This requires both prescription of an adequate dose of HD and regular assessment that the delivered treatments are also adequate. Online conductivity monitoring using sodium flux as a surrogate for urea allows the repeated noninvasive measurement of Kt/V on each HD treatment.
Methods: We prospectively studied 17 (9 males, 8 females) established chronic HD patients over an eight-week period (408 treatments). A pre- and post-dialyzer measurement of the conductivity is performed by two mutually independent temperature-compensated conductivity cells equipped with Fresenius 4008 S® dialysis machines. Urea reduction was measured (once a week) by a single pool calculation using immediate post-treatment sampling. No changes were made to any of the dialysis prescriptions over the study period. Values of calculated Kt/V and simultaneously obtained online Kt/V were compared.
Results: There was a statistically significant difference between calculated Kt/V and online Kt/V over the study period. The mean calculated Kt/V was 1.37 ± 0.09, and mean online Kt/V 1.02 ± 0.15 (P = 0.000), calculated Kt/V ≥ 1.2 was achieved in all our patients while online Kt/V ≥ 1.2 was achieved in only 17.64 %. Yet there was moderate correlation between calculated Kt/V and online Kt/V (r2 = 0.48).
Conclusions: Online conductivity monitoring results underestimates dialysis efficiency compared to calculated Kt/V readings. This difference has to be considered when applying Kt/V to clinical practice.
Keywords: Kt/V, hemodialysis, online conductivity monitoring
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