Estimation of Filtration Coefficients and Circulating Plasma Volume by Continuously Monitoring Hematocrit during Hemodialysis

Abstract

Background/Aims: Filtration coefficients (Lp) and plasma volume were estimated in order to investigate whether suppressed Lp associates with intradialytic hypotension and/or diabetic nephropathy. Methods: Twenty-one patients were evaluated. Nine patients were diabetic (DM) and 12 were nondiabetic (non-DM). Three of DM and 4 of non-DM were prone to dialysis-induced hypotension (hypo(+)) and others (hypo(–)) were not. Changes in hematocrit (Ht) were measured for 60 min after the start of ultrafiltration. Lp and plasma volume at the start of ultrafiltration (Vp0) were estimated to fit calculating values of Ht based on Schneditz’s open two compartment model to actual value. Results: There was no significant difference in the mean values of Lp/Vp0 either between hypo(+) and hypo(–) (0.87 ± 0.37 vs. 1.24 ± 0.48 ml/mm Hg·min·liter; n.s.) or between DM and non-DM (1.04 ± 0.32 vs. 1.17 ± 0.56 ml/mm Hg·min· liter; n.s.). However, the comparisons of Lp/Vp0 among the four groups (hypo(+)/DM, hypo(–)/DM, hypo(+)/non-DM and hypo(–)/non-DM) showed significant differences between hypo(+)/non-DM and hypo(–)/non-DM (1.08 ± 0.40, 1.02 ± 0.32, 0.71 ± 0.29*, 1.40 ± 0.53* ml/mm Hg·min·liter; *p < 0.05). Differences in the percentage of Vp0 to body weight (Vp0/BW) among four groups and correlation between Lp/Vp0 and Vp0/BW were not significant. Conclusion: These data indicated that reduction of Lp/Vp0 was not simply caused by decreased circulating plasma volume (Vp0/BW) and that the suppressed filtration coefficients may have substantial association with dialysis-induced hypotension in non-DM. The estimation of Lp using in-line measurement of Ht was a useful method for analyzing intradialytic hypotension.

Kinetics of Plasma Refilling During Hemodialysis Sessions with Different Initial Fluid Status

“…3,[6][7][8][9][10][11][12][13][14] Continuous on-line blood volume monitoring was applied by some authors to obtain qualitative characteristics of the process of refilling and its relation to hypotensive episodes. 3,[15][16][17][18][19][20][21] The quantitative analysis of the refilling process may be based on a two-compartment model to describe the rate of plasma refilling through the application of the Starling equation to the kinetics of plasma volume, V p , during dialysis session 22 :…”

Relationship between Filtration Coefficients of Microvasculature and Levels of Atrial Natriuretic Peptide or Echocardiographic Measurements

“…However, as we have reported previously [12] , the initial circulating plasma volume is estimated to be 5.6 8 0.2% of body weight. If the Ht is assumed to be 30%, the calculated blood volume is about 8.0%.…”

“…The initial circulating blood volume was supposed to be 7.7% of the initial body weight [2] . The assumptions for calculation were similar to those of Schneditz et al [6] and of our previous reports [12] , described briefl y as follows: (1) Cref was 0.007 g/ml.…”

Simulation of post-dialysis urea rebound using regional flow model

“…13 The following 13 different methods of estimating parameter sets were used: The values in parentheses are the values substituted in each method. The employed values of fQH ϭ 0.8 and fVH ϭ 0.2 were reported by Schneditz et al 10 and the values of fQH ϭ 0.85 and fVH ϭ 0.2 were also reported by Schneditz et al 11 The ratios of fQH to fVH in methods 5a and 5b are same as those reported by Schneditz et al 10 and Schneditz et al, 11 respectively.…”