Abstract: SA-PO781

Measurement of Fluid Shifts during 15 Minutes of Standing Using Bioimpedance in Hemodialysis Patients and Healthy Subjects

Session Information

Category: Dialysis

  • 601 Standard Hemodialysis for ESRD

Authors

  • Tao, Xia, Renal Research Institute, New York, New York, United States
  • Zhu, Fansan, Renal Research Institute, New York, New York, United States
  • Thwin, Ohnmar, Renal Research Institute, New York, New York, United States
  • Preciado, Priscila, Renal Research Institute, New York, New York, United States
  • Rosales, Laura, Renal Research Institute, New York, New York, United States
  • Thijssen, Stephan, Renal Research Institute, New York, New York, United States
  • Kotanko, Peter, Renal Research Institute, New York, New York, United States
Background

The InBody 770 bioimpedance device allows measurements of fluid status and body composition. Due to gravity, body fluid can shift from the trunk to the legs while standing. The aim of this study was to investigate if gravity-induced fluid shifts produce detectable changes in fluid distribution and if the magnitude of fluid shifts differs between hemodialysis (HD) patients and healthy subjects (HS).

Methods

We studied ten HD patients (7 males, age 58.1±12 years), pre and post HD, and 12 HS (7 females, age 33.3±5.6 years). Two measurements were performed 15 minutes apart in a standing position with the InBody 770 (InBody USA, Cerritos, CA, USA). Extracellular (ECW), intracellular (ICW), and total body water (TBW), ECW in the right and left leg (ECWRL; ECWLL) and the trunk (ECWT) were recorded. ECW/TBW ratio was calculated with measurements at the start of observation period. Repeated measurements were compared by paired t-test. Unpaired t-test was used to compare patients to HS for ECW/TBW ratio.

Results

During the 15-minute observation period, no significant change in TBW, ICW, or total and trunk ECW occurred. Leg ECW increased significantly for both patients and healthy subjects. In HD patients, the observations above were true both pre and post HD (average fluid removal on HD: 2.2 kg). Pre-HD ECW/TBW differed significantly from post-HD in patients and from HS.

Conclusion

Fifteen minutes of standing did not produce measurable changes in whole body ECW or TBW. However, leg ECW did increase significantly over this period, and this was true in healthy subjects, HD patients before dialysis, and HD patients after fluid removal.

Table 1: The differences (Δ) were calculated as the respective fluid compartment changes over a period of 15 minutes.
StudiesΔTBW (L)ΔICW (L)ΔECW (L)ΔECWRL (L)ΔECWLL (L)ΔECWT (L)ECW/TBW
Pre-HD0.300±0.4780.180±0.3290.120±0.1620.036±0.035*0.038±0.035*0.030±0.0820.393±0.013
Post-HD-0.060±0.272-0.080±0.1870.020±0.0920.029±0.020*0.036±0.017*0.000±0.0670.385±0.012**
Healthy subjects0.000±0.186-0.025±0.1600.025±0.0620.031±0.024*0.035±0.017*0.008±0.0790.378±0.006**

*p<0.01, data compared for the 15-minute interval. ** p<0.01, compared to pre-HD results.

Funding

  • Commercial Support