Daily use of the physio dialysis system: long-term experience

Hypovolaemia has been implicated as a major causal factor of morbidity during haemodialysis (HD). In order to avoid the appearance of destabilising hypovolaemia a biofeedback control system for intra-HD blood volume (BV) change modelling has been developed (Hemocontrol, Hospal Italy). It is based on an adaptive controller incorporated into a HD machine (Integra, Hospal Italy). The Hemocontrol biofeedback system (HBS) monitors BV contraction during HD with an optical device; furthermore, HBS modulates BV contraction rates (by adjusting the ultrafiltration rate--UFR) and the refilling rate (by adjusting dialysate conductivity--DC) in order to obtain the desired pre-determined BV trajectories.

Nineteen patients prone to hypotension (7 males, 12 females, mean age 64.5 +/- 3.0 SEM years, on maintenance HD for 80.5 +/- 13.2 months) volunteered for the prospective study which aimed to compare the efficacy and safety of bicarbonate HD treatmentequipped with HBS, as a whole (HBS),with the gold standard, bicarbonate treatment, equipped with a constant UFR and DC (BD). The study included one period of 6 months of BD always preceding a follow-up period of HBS treatment ranging from 14 to 30 months (mean 24.0 +/- 1.6).

The overall occurrence of symptomatic hypotension and muscle cramps was significantly less in HBS treatment. Self-evaluation of intra- and inter-HD symptoms (the worst score was o and the best one 10) did reveal a statistically significant difference, as far as post-HD fatigue is concerned (6.2 +/- 0.2 in HBS vs. 4.3 +/- 0.1 in BD treatment, p < 0.0001). No difference between the two treatments was observed when comparing pre- and post-HD lying blood pressure, heart rate, body weights and body weight changes.

HBS is an effective treatment. Hypovolaemia-associated morbidity occurs less in BD treatment than HBS. Furthermore, HBS is a safe treatment in the medium-term because these results are achieved without potentially harmful changes in blood pressure, body weight and serum sodium concentration.