Importance of Body Water in the Efficacy of Convective Solute Transport in Online Hemodiafiltration

Abstract

High-volume online hemodiafiltration (OL-HDF) has been associated with improved patient survival compared to conventional hemodialysis in recent trials, where the importance of convective volume (CV) in this benefit is noted. The purpose of this study was to determine the corporal composition parameters influencing the efficacy of CV in the removal of different molecular weight (MW) molecules. Demographic data, corporal composition parameters with bioimpedance spectroscopy, dialysis features and the reduction rates of different MW molecules in a four-hour OL-HDF session were collected in 61 patients. We observed a significant negative correlation of β2-microglobulin, cystatin-C, myoglobin and prolactin reduction rates with body surface area, weight, total body extracellular (ECW) and intracellular water (ICW), lean tissue mass and body cellular mass. The multivariable regression analysis identified ECW and ICW as the only corporal composition factors independently associated to the relative elimination of β2-microglobulin (Beta: -0.801, P = 0.002 for ECW and Beta: -1.710, P = 0.001 for ICW), cystatin-C (Beta: -0.656, P = 0.010 for ECW and Beta: -1.511, P = 0.004 for ICW) and myoglobin (Beta: -0.745, P = 0.014 for ECW and Beta: -2.103, P = 0.001 for ICW), in addition to CV. Prolactin reduction was only associated with ICW (Beta: -1.540, P = 0.028). When adjusting CV with ECW and ICW, only the ratio CV/ECW was an independent predictor for higher elimination of β2-microglobulin, cystatin-C and myoglobin. The corporal composition parameters independently associated to the reduction of medium-sized molecules are the extracellular and intracellular water. The ratio "convective volume/extracellular water" predicts higher efficacy of convective transport. Adjusting the convective volume to patient features could be useful to monitor the efficacy of OL-HDF and to prescribe individualized therapies.

Convection volume, β2‐microglobulin and α1‐microglobulin reduction ratios, and body composition in pre‐dilution online haemodiafiltration

“…Davenport et al reported that an associated survival advantage for higher CV was observed when the CV was adjusted according to body surface area or TBW, using surrogate estimates of lean body mass, rather than body weight or BMI (which is more related to fat mass), in patients on Post‐OL‐HDF 6 . Consistent with previous reports on CV adjusted to body water in Post‐OL‐HDF, 7,8 we found that CV/ECW, CV/TBW and CV/ICW, but not CV alone, were significantly associated with RRs of β2‐microglobulin and α1‐microglobulin in patients on Pre‐OL‐HDF. The importance of body water in the efficacy of RRs of β2‐microglobulin and α1‐microglobulin in Pre‐OL‐HDF was confirmed in this study.…”

“…Effects of higher convection volume (CV) on nutritional status, body compositions and survival advantage have drawn attention in Post‐OL‐HDF 5,6 . However, CV has different effects on the elimination of solutes that depend on the patient's fluid composition 7 . Macías et al reported that the ratios of CV/extracellular water (ECW) 7,8 and CV/total body water (TBW), 8 but not CV alone, were independent predictors for higher elimination of β2‐microglobulin and other protein‐bound uraemic toxins in patients on Post‐OL‐HDF 7,8 .…”

“…5,6 However, CV has different effects on the elimination of solutes that depend on the patient's fluid composition. 7 Macías et al reported that the ratios of CV/extracellular water (ECW) 7,8 and CV/total body water (TBW), 8 but not CV alone, were independent predictors for higher elimination of β2-microglobulin and other protein-bound uraemic toxins in patients on Post-OL-HDF. 7,8 To date, few studies have examined body composition in patients on Pre-OL-HDF.…”

“…7 Macías et al reported that the ratios of CV/extracellular water (ECW) 7,8 and CV/total body water (TBW), 8 but not CV alone, were independent predictors for higher elimination of β2-microglobulin and other protein-bound uraemic toxins in patients on Post-OL-HDF. 7,8 To date, few studies have examined body composition in patients on Pre-OL-HDF. We studied associations between reduction ratios (RRs) of β2-microglobulin and α1-microglobulin and CV, CV adjusted to body water [CV/ECW, CV/TBW, and CV/intracellular water (ICW)], and body composition parameters in patients on Pre-OL-HDF.…”

Requirements and Pitfalls of Dialyzer Sieving Coefficients Comparisons

“… Correlation of clinical beta‐2 microglobulin reduction ratio (β 2 M RR) data and sieving coefficient using (A) values reported in data sheets and instructions for use and (B) values measured under identical testing conditions (per the methodology stated in ISO 8637, using human plasma with Q B /UF of 300/60mL/min) . HD, hemodialysis; HDF, hemodiafiltration.…”