New method to set dry weight by monitoring blood volume during hemodialysis

Abstract

We developed a new optical device (Nikkiso Co., Ltd.) to assess changes through blood volume monitoring (BVM) during hemodialysis and were able to determine the ideal levels when changes in blood volume (BV%) occur in hemodialysis patients. We evaluated the significance of BVM for setting the post-dialytic body weight in a multicenter group. Previously, we obtained the ideal level of BV% in patients whose dry weight was suitable. Upper limit line : BV%/BW%end=-0.437t-0.005. Lower limit line : BV%/BW%end=-0.245ln(t)-0.645t-0.810. When BV% is within this range, we can consider the dry weight suitable. BV was monitored three times in each patient. Of 430 measurements obtained from 144 hemodialysis patients from nine hemodialysis centers, 94 measurements were excluded because they were outside the protocol. A total of 230 of 336 measurements were obtained from patients whose dry weights were considered suitable under the criteria established by each center. For 167 measurements (72.6%), post-dialytic body weight was also considered suitable by BVM. The causes of inconsistencies between findings on BVM and clinical evaluation were blood access recirculation, positional changes during monitoring, and body weight gain of less than 1.0kg. There was a consistent ratio of 71.6% between the evaluation by BVM and that by PWI (plasma weight index : index of the ratio of circulating plasma volume change per body weight change). There was a consistent ratio of 68.8% between the evaluation by BVM and that by hANP (25≤ANP≤75 (pg/mL). We conclude that BVM is a useful index for setting post-dialytic body weight in clinical practice, and the greatest benefit is that BVM facilitates the visualization of blood volume changes in real time.