Online evaluation of adequacy of blood dialysis using electrical conductivity and comparison with in vitro assay of serum urea reduction

Abstract

Although determining the appropriate and adequate dose of hemodialysis by monitoring the hemodialysis adequacy of patients is very important, Iranian hemodialysis guidelines for measuring the hemodialysis adequacy still emphasize the traditional laboratory evaluations of pre-and-post dialysis blood smaples for this purpose despite all advantages of the Online Clearance Measurement (OCM) method using electrical conduction over the laboratory evaluations method. The aim of current study was to compare the hemodialysis adequacy using OCM method with laboratory evaluations to introduce an efficient method for measuring hemodialysis adequacy in Iran hemodialysis centers. Materials and Methods: This cohort study was performed over 301 patients undergoing hemodialysis with fixed hemodialysis profile who were referred to Imam Reza Hemodialysis Center in Tabriz during 2019. Hemodialysis adequacy of each patient was assessed using two methods. In laboratory evaluation method, 2cc of blood samples was taken from the arterial line before and after the dialysis session to calculate the Urea Reduction Ratio (URR). In OCM method, the hemodialysis machine measured the rate of patient urea changes based on sodium dialysis fluid changes and presented the value of Kt /V was using electrical conductivity. The urea clearance values obtained from these two methods were compared with each other. Results: In this study, the mean age and BMI of patients were 60.7±14.6 years and 20.8±3.9, respectively. 67.1% of patients were male. 81.4% of patients needed 3 weekly hemodialysis sessions. Access dialysis type in 66.8% of patients was venous arterial fistula and dialysis filter type in 57.8% of cases was High Flux. In patients, mean amounts of hematocrit, UDV, UF and blood flow were 35.8±5.5%, 36.7±13.3, 2.5±1.2 and 275.2±19.6 mm/min, respectively. The mean URR was 1.20±0.23 and the mean Kt/V was 1.11±0.21, which were not significantly different from each other (P = 0.503).