Replenishing Alkali During Hemodialysis: Physiology-Based Approaches

Gennari, F. John; Marano, Marco; Maranò, Stefano

doi:10.1016/j.xkme.2022.100523

Cited by 5 publications

(8 citation statements)

References 27 publications

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“…In clinical practice a lack of equilibration between plasma and dialysate bicarbonate concentration is often observed, despite a leveling-off of plasma bicarbonate [15][16][17]; Gennari et al [49] have recently summarized some possible explanations for this lack of equilibrium. In one case [26], Sargent et al proposed that this lack of equilibration was the result of increased endogenous organic acid production; however, recent data from Park et al [31] do not support endogenous acid production as the dominant mechanism.…”

Section: Plos Onementioning

confidence: 99%

Mathematical modelling of bicarbonate supplementation and acid-base chemistry in kidney failure patients on hemodialysis

Pietribiasi

Waniewski²,

Leypoldt³

2023

PLoS ONE

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Acid-base regulation by the kidneys is largely missing in end-stage renal disease patients undergoing hemodialysis (HD). Bicarbonate is added to the dialysis fluid during HD to replenish the buffers in the body and neutralize interdialytic acid accumulation. Predicting HD outcomes with mathematical models can help select the optimal patient-specific dialysate composition, but the kinetics of bicarbonate are difficult to quantify, because of the many factors involved in the regulation of the bicarbonate buffer in bodily fluids. We implemented a mathematical model of dissolved CO2 and bicarbonate transport that describes the changes in acid-base equilibrium induced by HD to assess the kinetics of bicarbonate, dissolved CO2, and other buffers not only in plasma but also in erythrocytes, interstitial fluid, and tissue cells; the model also includes respiratory control over the partial pressures of CO2 and oxygen. Clinical data were used to fit the model and identify missing parameters used in theoretical simulations. Our results demonstrate the feasibility of the model in describing the changes to acid-base homeostasis typical of HD, and highlight the importance of respiratory regulation during HD.

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Section: Plos Onementioning

confidence: 99%

Mathematical modelling of bicarbonate supplementation and acid-base chemistry in kidney failure patients on hemodialysis

Pietribiasi

Waniewski²,

Leypoldt³

2023

PLoS ONE

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“…2 It remains unclear how to optimise alkali delivery from dialysis solution to both neutralise interdialysis acid generation yet minimise postdialysis alkalosis. 10–12…”

Section: Introductionmentioning

confidence: 99%

“…14,15 Further, the H + mobilization model has proposed novel dialysis fluid compositions of alkali 16 or time-dependent dialysate [HCO 3 ] profiles 17,18 that may potentially minimise intradialysis organic acid generation that has been proposed to be maladaptive and undesirable. 11,13 Other acid-base kinetic models based on the electroneutrality of ions 19 or a more complete description of whole body acid-base chemistry 20 have also been described.…”

Section: Introductionmentioning

confidence: 99%

“…2 It remains unclear how to optimise alkali delivery from dialysis solution to both neutralise interdialysis acid generation yet minimise postdialysis alkalosis. [10][11][12] Several theoretical studies have recently proposed new approaches for optimising the delivery of alkali from dialysis solution during chronic HD treatments. The most extensively model studied is that developed by Sargent et al, 13 the hydrogen ion (H + ) mobilization model, that describes intradialysis blood HCO 3 kinetics assuming HCO 3 is distributed in the extracellular fluid volume and is removed from that space by mobilisation of H + from buffers and other sources.…”

mentioning

confidence: 99%

“…13 In that study, the dialysate [HCO 3 ] was increased 8 separate times during the HD treatment, but such an approach may not be practical in a busy dialysis centre. 11 A more recent crossover clinical trial where the dialysate [HCO 3 ] was increased or decreased after the first 2 hours of an HD treatment has been reported elsewhere. 22,23 In the current study we compared model predictions from the H + mobilization model with data from the latter clinical study to test the hypothesis that the parameter H m can be considered constant when using a time-dependent dialysate [HCO 3 ].…”

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confidence: 99%

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Validity of the hydrogen ion mobilisation model during haemodialysis with time-dependent dialysate bicarbonate concentrations

et al. 2023

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Background: The hydrogen ion (H+) mobilisation model has been previously shown to accurately describe blood bicarbonate (HCO3) kinetics during haemodialysis (HD) when the dialysate bicarbonate concentration ([HCO3]) is constant throughout the treatment. This study evaluated the ability of the H+ mobilization model to describe blood HCO3 kinetics during HD treatments with a time-dependent dialysate [HCO3]. Methods: Data from a recent clinical study where blood [HCO3] was measured at the beginning of and every hour during 4-h treatments in 20 chronic, thrice-weekly HD patients with a constant (Treatment A), decreasing (Treatment B) and increasing (Treatment C) dialysate [HCO3] were evaluated. The H+ mobilization model was used to determine the model parameter (Hm) that provided the best fit of the model to the clinical data using nonlinear regression. A total of 114 HD treatments provided individual estimates of Hm. Results: Mean ± standard deviation estimates of Hm during Treatments A, B and C were 0.153 ± 0.069, 0.180 ± 0.109 and 0.205 ± 0.141 L/min (medians [interquartile ranges] were 0.145 [0.118,0.191], 0.159 [0.112,0.209], 0.169 [0.115,0.236] L/min), respectively; these estimates were not different from each other ( p = 0.26). The sum of squared differences between the measured blood [HCO3] and that predicted by the model were not different during Treatments A, B and C ( p = 0.50), suggesting a similar degree of model fit to the data. Conclusions: This study supports the validity of the H+ mobilization model to describe intradialysis blood HCO3 kinetics during HD with a constant Hm value when using a time-dependent dialysate [HCO3].

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