Compartment Effects in Hemodialysis

Schneditz, Daniel; Daugirdas, John T.

doi:10.1046/j.1525-139x.2001.00066.x

Cited by 77 publications

(40 citation statements)

References 30 publications

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“…Furthermore, the equations are based on the parallel regional blood flow model of urea kinetics, which is a complex model with a large number of assumed parameters [29]. The parallel regional blood flow model is also not supported by the observation of normal rebound ratios despite increased urea clearance with extra dialysis time [30,31,32]. …”

Section: Discussionmentioning

confidence: 99%

“…With regard to β 2 M kinetics during dialysis, a simpler serial two-pool model has been suggested whereby the intercompartmental transfer coefficient appears to be the rate-limiting factor of removal [17,32]. The flux of this molecule between compartments is relatively slow and does not reach its maximum during a standard HD session, thus encouraging recommendations for increased dialysis duration rather than more efficient dialysis sessions for enhanced middle molecule clearance [17].…”

Section: Discussionmentioning

confidence: 99%

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Interaction between Intradialytic Exercise and Hemodialysis Adequacy

Kirkman¹,

Roberts²,

Kelm³

et al. 2013

Am J Nephrol

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Background/Aims: According to mathematical modeling, intradialytic exercise of sufficient intensity and duration implemented in the second half of dialysis should be as efficacious as increasing dialysis time for dialysis adequacy. This assumption has not been tested in vivo. Methods: In this controlled trial, 11 hemodialysis (HD) patients (mean (SD) age 56 (13) years) were recruited. Each patient completed three trial arms in a randomized order: routine care (CONT), increased HD time of 30 min (TIME), and intradialytic exercise (EXER), 60 min of cycling at 90% of the lactate threshold in the last 90 min of HD. The primary outcome was eKt/V_urea. Secondary outcomes included reduction and rebound ratios of urea, creatinine, phosphate and β₂-microglobulin.Outcomes were calculated from blood sampling collected pre-, post- and 30 min post-HD and confirmed with dialysate sampling. Results: Exercise was not as efficacious as increased HD time for eKt/V_urea (EXER vs. CONT, mean change (95% CI): 0.03 (-0.05 to 0.12); TIME vs. CONT: 0.15 (0.05-0.26)). Exercise was less efficacious at improving reduction ratios of urea and creatinine. However, exercise was more efficacious than increased dialysis time for phosphate reduction ratio (EXER vs. CONT: 8.6% (0.5-16.7); TIME vs. CONT: 5.0% (-1.0 to 11.1)). Conclusion: This study utilized a rigorously controlled in vivo design to test mathematical models and assumptions regarding dialysis adequacy. Intradialytic exercise towards the end of HD cannot replace the prescription of increased HD time for dialysis adequacy, but may be an adjunctive therapy for serum phosphate control.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Interaction between Intradialytic Exercise and Hemodialysis Adequacy

Kirkman¹,

Roberts²,

Kelm³

et al. 2013

Am J Nephrol

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“…Serum intact parathormone (i-PTH) was measured by using ELISA before dialysis. The dialysis adequacy was evaluated by the estimation of equilibrated Kt/V [22]. Blood samples were taken immediately after the end of an HD session (after 10–15 s of 50–100 ml/min blood flow).…”

Section: Methodsmentioning

confidence: 99%

Effect of Haemodialysis on Regional and Transmural Inhomogeneities of the Ventricular Repolarisation Phase

Jaroszyński

Załuska²,

Książek³

2005

Nephron Clin Pract

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Recent studies have indicated increased ventricular repolarisation dispersion in haemodialysis (HD) patients. The purpose of this study was to estimate the effect of the HD process on parameters of regional and transmyocardial repolarisation inhomogeneities. Thirty-two selected HD patients (without relevant diseases and medication known to affect the QT interval) were included. Dispersion of the QT corrected interval (QT-c-D) and the corrected interval between the peak and the end of the T wave (Tpe-c-D) were evaluated before and after HD, and in controls. Blood chemistry and extracellular body water (ECW) were evaluated before and after HD. Predialysis QT-c-D and Tpe-c-D were higher in patients (53.40 ± 17.39 and 47.50 ± 13.68 ms, respectively) than in controls (34.91 ± 17.70 ms, p < 0.001 and 31.9 ± 16.76 ms, p < 0.001, respectively). HD induced an increase in the QT-c-D (67.59 ± 19.40 ms; p < 0.001) and Tpe-c-D (62.89 ± 14.33 ms; p < 0.001). Stepwise multiple regression identified the independent risk factors of QT-c-D (the differences between pre- and postdialysis phosphorus, potassium and calcium levels and ECW values) and Tpe-c-D (the differences between pre- and postdialysis phosphorus levels, calcium levels and ECW values) increases, induced by the HD process. The HD process increases regional and transmyocardial repolarisation phase inhomogeneities in HD patients. Changes of phosphorus, calcium and potassium levels plus ECW values seem to be important predisposing factors as far as the increase in ventricular inhomogeneities in HD patients is concerned.

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“…However, because the rapid removal of BUN during HD causes a concentration disequilibrium between intracellular and extracellular fluid spaces, BUN increases immediately following HD. This phenomenon is well known as the urea rebound, and is due to the multiple-pool nature of the human body, and mass transfer resistance of the biological membranes and variations in regional blood flows (Schneditz & Daugirdas, 2001), Yashiro et al, 2004). Since Kt/V calculation is based in part on the post-hemodialysis BUN level, urea rebound has a significant impact upon the calculation of the delivered dose of hemodialysis.…”

Section: Problem Statementmentioning

confidence: 99%