The application of fuzzy logic in the blood-pressure-guided biofeedback control of ultrafiltration and sodium infusion during haemodialysis is able to minimize haemodialysis-induced hypotension.

BACKGROUND The prevalence of intradialytic hypotensive events is still high in patients undergoing hemodialysis (HD). A biofeedback control system to prevent hypotensive destabilization of the patient during hemodialysis was developed. METHODS A blood pressure (BP)–guided closed‐loop system consists of a non‐invasive blood pressure measurement device connected to a fuzzy controller (FC). It regulates ultrafiltration rate (UFR) and dialysate conductivity (DC) depending on the actual BP and its short‐ and long‐term trends as well. Twenty‐eight HD patients prone to hypotension were selected for the study. In 102 HD sessions it was proven whether an increase in DC from 14.3 mS/cm to a maximum of 17.0 mS/cm infl uenced the serum sodium concentration of the patients and interdialytic weight gain (IDGW), when DC was reset to 14.3 mS/cm for the remaining 60 minutes of treatment. In the next step, 69 conventional HD sessions without the fuzzy controller and 144 sessions with fuzzy‐controlled ultrafiltration were compared with 32 sessions with simultaneous fuzzy‐controlled ultrafiltration and modification of dialysate conductivity. RESULTS No significant differences in serum sodium concentration and weight gain were observed when DC was reset for the remaining 60 minutes of treatment. In conventional HD the frequency of low blood pressure situations, <90 mmHg, increased progressively toward the end of the treatment. The HD treatments with fuzzy‐controlled UFR resulted in no increases in the number of hypotensive episodes. Moreover, there was a significant decrease in the third and fourth treatment hours. The simultaneous fuzzy control of UFR + DC resulted in the lowest occurrence of BP drops. CONCLUSIONS Fuzzy control of HD treatments provides reliable blood pressure stabilization in patients prone to hypotension. This kind of treatment is safe because significant changes in body weight and serum sodium concentration do not occur. The cost of this treatment is limited because no special disposables are necessary.