Blood Pressure Guided Profiling of Ultrafiltration during Hemodialysis

Hemodialysis-induced hypotension is still a common complication in spite of the progress achieved in hemodialysis (HD) treatment. Due to its multifactorial nature, dialysis-induced hypotension cannot be reliably prevented by conventional profiling of ultrafiltration in open-loop systems since they are unable to adapt themselves to actual decreases in blood pressure. A blood pressure guided closed-loop system for prevention of dialysis-induced hypotension by biofeedback-controlled profiling of ultrafiltration was clinically tested in 94 HD treatments of four patients prone to hypotension. Automatic profiling of ultrafiltration was based on frequent measurements of blood pressure at intervals of five minutes. Proper adaptation of control features to patients' conditions was provided by the lower limit of systolic pressure which was individually set by the physician at the beginning of each treatment. During the initial and medium phases of the HD sessions, ultrafiltration rates up to 200% of the average rates were applied as long as this was tolerated. The additional ultrafiltrate volume was used for blood pressure stabilization by lowering the ultrafiltration rates in the final phase of HD session. Biofeedback-controlled profiling of ultrafiltration provides reliable blood pressure stabilization in all phases of HD. During the first half of treatment, the frequency of hypotensive episodes remained below that with conventional therapy although ultrafiltration rates up to 200% were used. During the second half of treatment, blood pressure guided reduction of ultrafiltration rate provided a decreasing frequency of hypotensive episodes in contrast to the increasing trend during conventional therapy. Stable blood pressure trends during the last hour of HD were achieved in 91% of biofeedback-controlled treatments in comparison with only 32% of conventional treatments. Ultrafiltration rates of 150%-200% and blood pressure measurements at intervals of five minutes were well tolerated, since hypotension-prone patients were better monitored.