EFFECT OF ONLINE CONDUCTIVITY PLASMA ULTRAFILTRATE KINETIC MODELING ON CARDIOVASCULAR STABILITY OF HEMODIALYSIS-PATIENTS

Effect of on-line conductivity plasma ultrafiltrate kinetic modeling o n cardiovascular stability of hemodialysis patients, The aim of this m ulticenter, prospective, randomized cross-over study was to clarify wh ether on-line conductivity ultrafiltrate kinetic modeling (treatment B ), as a substitute for sodium kinetic modeling, is capable of reducing intradialytic cardiovascular instability in comparison with standard treatment (treatment A), by reducing the sodium balance variability. B oth treatments were performed by means of a modified hemodiafiltration technique. Treatment A was performed using fixed dialysate conductivi ty; treatment B made use of the dialysate conductivity derived from a conductivity kinetic model. in order to obtain an end-dialysis ultrafi ltrate conductivity at each dialysis session that was equal to the mea n value determined in the same patient during the four-week run-in per iod. Thus, during treatment B, the expected end-dialysis ultrafiltrate conductivity value of each patient should have been constant. The stu dy was carried out according to a multicenter cross-over design of 16 weeks with two treatments (A or B), two sequences (1 = ABB and 2 = BAA ), a run-in period of four weeks (period 1, treatment A), and three co nsecutive experimental periods of four weeks each. Analysis of varianc e for a cross-ever design was used for the statistical analysis. Forty -nine hemodialysis patients prone to intradialytic hypotension (> 25% of sessions) were enrolled from 16 participating centers, and randomly assigned to either sequence 1 (26 patients) or sequence 2 (23 patient s). Six patients dropped out and four were protocol violators, which l eft 39 patients selected for statistical analysis. There was no differ ence in the average dialysate conductivity, predialysis and end-dialys is plasma water ultrafiltrate conductivity or body weight between trea tment A and treatment B. Thus. the observed mean sodium balance was no t different and, as expected, only the intra-patient variability of en d-dialysis ultrafiltrate conductivity (index of sodium balance variabi lity) was reduced (21%). During treatment A, systolic blood pressure d ecreased by 23 mm Hg (95% confidence intervals 21 to 24 mm Hg) at the end of dialysis with respect to the pre-dialysis values. Treatment B r educed this intradialytic decrease (P = 0.001) with a maximum effect a t the third hour of dialysis (4.4 mm Hg, 95% confidence intervals 1.9 to 6.9 mm Hg, 23% less than during treatment A, P 0.0005) without any period or carry-over effect (P = 0.53 and 0.08, respectively). There w as no treatment effect on intradialytic diastolic blood pressure (P = 0.291). In conclusion, intradialytic cardiovascular stability was sign ificantly improved by matching the interdialytic sodium load viith int radialytic sodium removal using on-line conductivity ultrafiltrate kin etic modeling as an alternative to sodium kinetic modeling. Although h ighly significant, this effect was clinically not very large. By apply ing this conductivity kinetic model to patients with a more variable s odium intake from one session to another, a greater benefit can be exp ected.