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Abstract: TH-PO247

Estimation of Absolute Blood Volume in Hemodialysis Patients Using Bioimpedance Spectroscopy

Session Information

Category: Dialysis

  • 801 Dialysis: Hemodialysis and Frequent Dialysis

Authors

  • Zhu, Fansan, Renal Research Institute, New York, New York, United States
  • Raimann, Jochen G., Renal Research Institute, New York, New York, United States
  • Moissl, Ulrich, Fresenius SE & Co KGaA, Bad Homburg, Hessen, Germany
  • Abbas, Samer R., Renal Research Institute, New York, New York, United States
  • Chamney, Paul William, Fresenius Medical Care (UK) Ltd, Huthwaite, United Kingdom
  • Thijssen, Stephan, Renal Research Institute, New York, New York, United States
  • Kotanko, Peter, Renal Research Institute, New York, New York, United States
Background

Measurement of absolute blood volume (ABV) during hemodialysis is essential to understand the relationship between the rates of vascular refilling and ultrafiltration. However, ABV is usually measured with dilution methods that are impractical in clinical routine. We evaluated whole body bioimpedance spectroscopy (wBIS) as an alternative approach.

Methods

Extracellular (ECV) and intracellular (ICV) volume were estimated using published equations (Moissl, Physiol Meas 27:921-933, 2006) based on wBIS measurements (Hydra 4200). Lean tissue mass (LTM) and adipose tissue mass (ATM) were calculated by a body composition model (BCM) (Chamney, Am J Clin Nutr 85:80 –89,2007). Reference blood volume (ABV_Dax) was measured by tracer dilution (Daxor BVA-100 analyzer, Daxor Corp., New York, NY, USA). Multiple regression and Bland-Altman analyses were used to determine the relationship of ABV with BCM and wBIS models, respectively.

Results

Data from 12 subjects (3 females, 53.8±15.2 years, pre-HD weight 85.6±19.7 kg) were analyzed. Pre-HD ECV (19.01±3.62 L), ICV (23.02±5.96 L), LTM (46.78±13.97 kg) and ATM (36.86±18.53 kg) were calculated, while ABV_Dax (5.58±1.20 L) was measured before HD. The BCM model (ABV_BCM=1.028+0.023*ATM+0.079*LTM) comprised LTM and ATM as independent variables (Fig. 1). The wBIS model (ABV_wBIS=0.711+0.141*ICV+0.085*ECV) comprised ECV and ICV as independent variables (Fig.2). ABV_Dax correlated with ABV_BCM (R2=0.84, p<0.0001; bias = -0.01±0.5 L) and with ABV_wBIS (R2=0.84, p<0.0001; bias=0.00±0.49 L). Since the head and parts of the feet and hands had not been measured by wBIS, the y-intercept in both regression models conceptually represents an estimate of the blood in these body parts.

Conclusion

Estimation of ABV by both ABV_BCM and ABV_wBIS models correlate with the reference method. Despite the small sample size, utilizing such simple models may provide an approach using wBIS to estimate ABV and, in conjunction with relative blood volume measurements, to monitor ABV during HD.