Efficacy and safety of haemodialysis treatment with the Hemocontrol (TM) biofeedback system: a prospective medium-term study

Background. Hypovolaemia has been implicated as a major causal factor of mo rbidity during haemodialysis (HD). A model biofeedback control system for i ntra-HD blood volume (BV) changes modelling has been developed (Hemocontrol (TM), Hospal Italy) to prevent destabilizing hypovolaemia. It is based on a n adaptive controller incorporated in a HD machine (Integra(TM), Hospal Ita ly). The Hemocontrol(TM) biofeedback system (HBS) monitors BV contraction d uring HD with an optical device. HBS modulates BV contraction rates by adju sting the ultrafiltration rate (UFR) and the refilling rate by adjusting di alysate conductivity (DC) in order to obtain the desired pre-determined BV trajectories. Methods. Nineteen hypotension-prone uraemic patients (seven males, 12 femal es; mean age 64.5 +/- 3.0 SEM years; on maintenance HD for 80.5 +/- 13.2 mo nths) volunteered for the present prospective study that compared the effic acy and safety of bicarbonate IID treatment equipped with HBS, as a whole, with the gold-standard bicarbonate treatment equipped with a constant UFR a nd DC (BD). The study included three phases: Medium-term studies started wi th one period of 6 months of ED and always had a follow-up period of HBS tr eatment ranging from 14 to 30 months (mean 24.0 +/- 1.6); short-term studie s started in September 1999, when all patients went back to ED treatment fo r a wash-out period of 4 weeks and a short-term study period of a further 3 weeks (phase A). Afterwards, they once again started HBS treatment for a w ash-out period of 4 weeks and a short-term study period of a further 3 week s (phase B). Every patient underwent acute studies during a single HD run, once during phase A and once in phase B. Resistance (R) and reactance (Xc) measurements were obtained utilizing a single-frequency (50 kHz) tetrapolar bioimpedance analysis (BIA). Extracellular fluid volume (ECV) was calculat ed from R, Xc, and height and body weight measurements using the convention al BIA regression equations. Results. The overall occurrence of symptomatic hypotension and muscle cramp s was significantly less in HBS treatment in both medium- and short-term st udies. Self-evaluation of intra- and inter-HD symptoms (worst score = 0, be st score = 10) revealed a statistically significant difference, as far as p ost-IID asthenia was concerned (6.2 +/- 0.2 in HBS treatment vs 4.3 +/- 0.1 in ED treatment, P < 0.0001). No difference was observed between the two t reatments when comparing pre- and post-ND lying blood pressure, heart rate, body weights and body weight changes in medium- and short-term studies. Th e residual BV%/<Delta>ECV% ratio, expression of the vascular refilling, was significantly higher during HBS treatment in acute studies. Conclusions. HBS treatment is effective in lowering hypovolaemia-associated morbidity compared with ED treatment: this could be related to a greater E CV stability. Further-more, I-IBS is a safe treatment in the medium-term be cause these results are not achieved through potentially harmful changes in blood pressure, body weight, and serum sodium concentration.