Dialysis Adequacy Sensor With Systematic Error Correction Algorithm for Hemodialysis Machines

During hemodialysis, real-time monitoring of patients’ dialysis adequacy on hemodialysis machines can prevent complications and improve the long-term survival rate of patients. However, current online monitoring technologies are limited by various shortcomings, such as low accuracy of the conductivity method, poor repeatability of the electrochemical method, and systematic errors in the ultraviolet (UV) spectrophotometry. Among them, UV spectrophotometry is more suitable for real-time monitoring of dialysis adequacy on hemodialysis machines because of its advantages of noncontact and high sampling rate. Here, this article proposes a dialysis adequacy sensor (DAS) based on UV spectrophotometry, and develops a correction algorithm by modeling the theoretical optical path to improve real-time monitoring accuracy. The error in the urea concentration ratio is reduced by about ten times in the laboratory environment, which proves the effectiveness of the calibration algorithm. Clinical trials have demonstrated that the proposed sensor and implemented correction algorithm can precisely monitor dialysis adequacy during patient treatment, which can greatly reduce the error from 133.9% to 5.56%. The sensor reliably tracks the fluctuations in urea clearance rates, providing an effective indication of dialysis adequacy, which demonstrates strong potential for broad application among hemodialysis machines.