Supplementary Material for: Influence of different hemodialysis biocontrols on the achievement of the convective volume

Introduction. Post-dilution on-line hemodiafiltration (OL-HDF) has been shown to reduce all-cause mortality in hemodialysis (HD) patients when high substitution volumes are achieved. To date, little emphasis has been placed on the impact of different biocontrols in achieving high replacement volumes. The aim of the present study is to compare the substitution volume achieved with three different monitors using the three available automatic systems. Methods. Prospective, observational cross-over study of prevalent patients on post-dilution OL-HDF. Each patient underwent 9 consecutive post-dilution OL-HDF sessions with each of the monitors included in the study: Artis, 6008 and Surdial X with the corresponding biocontrol: UltraControl, AutoSub+ and Max-Sub respectively. After each session, the final convective volume and other parameters related to HD and medium-molecule clearance were collected. Results. Thirteen patients were included (57% male, age 62±14 years), of whom 71% were dialysed via an arteriovenous fistula (AVF). The mean time on dialysis was 51±32 months. Convective volume achieved with Max-Sub biocontrol (Surdial X monitor) was higher than that achieved with UltraControl biocontrol (Artis monitor) (29.1±2.1 vs 27.2±2.1 L/session, p=0.006) and AutoSub+ biocontrol (6008 monitor) (29.1±2.1 vs 27±3 L/session, p=0.01). On multivariate analysis, factors associated with higher convective volume were the prescription of Max-Sub biocontrol (B 1.61, 95% CI [0.41-2.80], p=0.009), TPM (B 0.02, 95% CI [0.01-0.03], p=0.018), blood processed (B 0.17, 95% CI [0.08-0.26], p<0.001) and not having diabetes mellitus (B -1.66 95% CI [-2.72-0.59], p=0.002) Conclusion. The volume achieved by convective transport can vary according to the type of biocontrol, with Max-Sub performing the best out of the 3 biocontrol systems.