Multicompartment urea kinetics in well-dialyzed children

Sharma, Atul; Espinosa, Pauline; Bell, Lorraine; Tom, Alex; Rodd, Celia

doi:10.1111/j.1523-1755.2000.00387.x

Cited by 18 publications

(9 citation statements)

References 34 publications

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“…During CECRT, plasma leucine concentrations in neonates with MSUD decrease according to a bi-exponential profile similar to the handling of nonprotein bound small molecular weight solutes such as urea (5,6). Our study is the first to define the distribution volumes of leucine in neonates and to propose leucine kinetic modeling that provides reliable prediction of the plasma leucine level changes during extracorporeal removal therapy with or without nutrition, thus precluding the need to perform repeated amino acid chromatography analysis.…”

Section: Discussionmentioning

confidence: 99%

“…A 4% albumin solution was used to prime the extracorporeal blood circuit and a sodium heparin solution was infused into the arterial line at a rate of 10 IU/kg/h to achieve an activated clotting time 1.5 times that of control. The same sterile nonpyrogenic fluid was used as either dialysate or replacement fluid and was prepared by mixing 5 Calculation. Leucine mass removal, N Leu , is the product of leucine concentration in the ultrafiltrate and spent dialysate and their volume.…”

Section: Patientsmentioning

confidence: 99%

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Kinetic Modeling of Plasma Leucine Levels during Continuous Venovenous Extracorporeal Removal Therapy in Neonates with Maple Syrup Urine Disease

et al. 2005

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A kinetic modeling of leucine plasma concentration changes is proposed to describe the plasma leucine reduction rate during continuous extracorporeal removal therapy (CECRT) in neonates with maple syrup urine disease. Data were obtained from seven neonates using a bicompartmental model for the best fitted curve of plasma leucine decrease during CECRT. During the first 3 h, leucine plasma levels decreased according to an exponential curve: [Leu] -0.05t . Plasma leucine levels obtained from three other neonates were similar to those predicted by the model. The apparent distribution volumes for leucine that correspond to the two exponential equations obtained were calculated from the leucine mass removal collected in the spent dialysate and ultrafiltrate. The distribution volume was 34 Ϯ 3% of body weight during the first 3 h of CECRT and 72 Ϯ 7% from h 4 to the end of CECRT. These figures are similar to known values for the extracellular water compartment and for total body water in the newborn. The findings suggest that leucine handling during CECRT is similar to that of nonprotein-bound small-molecularweight solutes such as urea. MSUD is an inherited metabolic disease due to a deficiency in branched chain ketoacid dehydrogenase that leads to the accumulation of BCAA (leucine, isoleucine, and valine) and their keto-acid derivatives (1). Because of this impaired enzyme activity, leucine accumulates in cells and body fluids when the load exceeds leucine metabolism capacity and/or when a increased protein catabolism occurs. Given that renal clearance of BCAA and its derivatives is poor and due to the fact that their acute elevation causes neurologic deterioration, CECRT is indicated in severe cases and/or when nutritional support free of BCAA is not possible (2).Because assessment of leucine plasma levels by amino acid chromatography is not easily available and is time consuming, the aim of this study was to design a kinetic model that predicts leucine plasma level changes over time during the acute phase of the illness in neonates on CECRT. METHODS Patients.Between January 1991 and April 2000, seven neonates with MSUD presented with a severe acute deterioration of their status. After a 6-h period of conservative management that included correction of dehydration and increased caloric intake, all seven patients presented two of the three following criteria that are associated with a high risk of severe brain damage: comatose state, gastrointestinal intolerance, and leucine plasma levels Ն1700 M. The patients were referred to pediatric and neonatal intensive care for alternative therapies, in particular CECRT (3). Blood and spent dialysate samples were collected to monitor treatment efficiency. We retrospectively used these biologic analyses to elaborate the parameters involved in leucine kinetic modeling during CECRT (Table 1). Subsequently, between May 2000 and December 2001, three other neonates were treated with the same therapeutic strategy and were retrospectively studied to validate the leucine kinetic model...

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Section: Discussionmentioning

confidence: 99%

Section: Patientsmentioning

confidence: 99%

Kinetic Modeling of Plasma Leucine Levels during Continuous Venovenous Extracorporeal Removal Therapy in Neonates with Maple Syrup Urine Disease

et al. 2005

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“…Over the ensuing 20 years, both pediatric and adult dialysis adequacy study focused mainly on deriving the most accurate mathematical formulae for quantifying urea clearance during hemodialysis or peritoneal dialysis [3,4,5,6]. While these studies led to more interest in the kinetics of dialysis and the creation of published national standards for adequate provision of hemodialysis, few studies have attempted to determine if higher urea clearance targets result in improvement in adult patient survival or morbidity.…”

Section: Introductionmentioning

confidence: 99%

Adequacy of dialysis in children: does small solute clearance really matter?

Goldstein

2004

Pediatric Nephrology

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Measurement of dialysis adequacy relies on an assessment of small molecule clearance during the dialysis procedure. However, recent adult studies (HEMO and ADEMEX) that pushed clearance to maximally achievable levels within practical constraints of thrice-weekly hemodialysis or four times daily continuous ambulatory peritoneal dialysis failed to demonstrate improvements in patient outcome above current guidelines. The relatively low incidence of pediatric compared with adult end-stage renal disease limits large-scale study of pediatric dialysis. Several single-center pediatric studies demonstrate a lack of association between small solute clearance alone and patient growth. The aim of the current article is to review the relevant pediatric and adult studies of small solute clearance and put them in the context of optimal dialysis provision. While small solute clearances do indeed matter, clearance is not all that matters. Our quest to provide optimal dialysis requires that we also focus our attention on patient nutritional status, increased dialysis delivery (daily/nocturnal hemodialysis), and adjunctive dialysis modalities (hemofiltration and renal tubular replacement therapy).

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“…Given the discrepancies between spKt/V and estimated eKt/V, we suggest that any pediatric study which controls for HD dose should use estimated eKt/V instead of spKt/V methods to most precisely quantify the delivered HD dose across the range of patient sizes and doses delivered in pediatric practice. Given the concerns cited above, more precise and validated formulas than the Daugirdas rate equation may be preferable for outcome study purposes [3,5], and certainly more study is required to confidently promote acceptance of the Daugirdas rate equation for standard clinical practice in estimating eKt/V in pediatric patients receiving hemodialysis.…”

Section: Discussionmentioning

confidence: 97%

“…The effect of post-dialysis urea rebound on the calculation of Kt/V has been the subject of significant recent research [2][3][4][5][6][7][8]. The relatively rapid removal of BUN during hemodialysis causes BUN concentration disequilibrium between intracellular (ICF) and extracellular (ECF) fluid spaces.…”

Section: Introductionmentioning

confidence: 99%

Comparison of single-pool and equilibrated Kt/V values for pediatric hemodialysis prescription management: analysis from the Centers for Medicare & Medicaid Services Clinical Performance Measures Project

et al. 2006

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Current formulas that estimate the delivered dose of hemodialysis rely upon pre- and post-treatment blood urea nitrogen (BUN) concentrations for calculation. Single-pool kinetic modeling (spKt/V) uses a convenient 30-s post-dialysis BUN sample but does not take urea rebound into account. Double-pool modeling (eKt/V) uses an equilibrated BUN (eqBUN) and is the best reflection of the true urea mass removed by hemodialysis but is inconvenient for patients and costly to the dialysis unit to wait to obtain an eqBUN sample. We compared simple spKt/V and eKt/V estimation formulas using data obtained from the Centers for Medicare & Medicaid Services (CMS) End Stage Renal Disease (ESRD) Clinical Performance Measures (CPM) Project to determine how frequently these two results would lead to different prescription management. We set an expected difference Kt/V (spKt/V-eKt/V) of 0.20 based on results of the Hemodialysis (HEMO) Study; 1,513 paired spKt/V and estimated eKt/V results were available for comparison. For patients with an arteriovenous fistula (AVF) or arteriovenous graft (AVG) (n=720), mean spKt/V and estimated eKt/V were 1.62+/-0.30 and 1.37+/-0.26, respectively. For patients with a catheter (n=793), mean spKt/V and estimated eKt/V were 1.53+/-0.32 and 1.33+/-0.29, respectively. Examination of the different spKt/V and estimated eKt/V pairings revealed a greater adequacy discordance rate between a 0.20 difference in spKt/V and estimated eKt/V at higher Kt/V values, but Kt/V discordance rates only varied from 0.3 to 5.5% depending on the paired Kt/V values used.

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Multicompartment urea kinetics in well-dialyzed children

Abstract: This VVDP model yields reliable estimates of K(d)t/V and other kinetic parameters using standard blood urea nitrogen sampling. Analysis of patients previously characterized as well-dialyzed on the basis of growth rates clarifies the HD dose needed to sustain normal growth.

Cited by 18 publications

References 34 publications

Kinetic Modeling of Plasma Leucine Levels during Continuous Venovenous Extracorporeal Removal Therapy in Neonates with Maple Syrup Urine Disease

Kinetic Modeling of Plasma Leucine Levels during Continuous Venovenous Extracorporeal Removal Therapy in Neonates with Maple Syrup Urine Disease

Adequacy of dialysis in children: does small solute clearance really matter?

Comparison of single-pool and equilibrated Kt/V values for pediatric hemodialysis prescription management: analysis from the Centers for Medicare & Medicaid Services Clinical Performance Measures Project

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