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1

Development of the power supply and control system for the hemodialysis machine

Yaskiv Volodymyr, Yaskiv Anna

Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska

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2023

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T. 13, nr 3

23--28

EN

The article describes new approaches to creating an autonomous compact system with automatic control for hemodialysis. It is proposed to organize a closed circuit for cleaning the dialysis solution using an electrolytic regenerator as a function of the concentration of urea in it. The functional diagram of the created system is presented and described. To power the regenerator, ensure thermal stabilization of the solution, and power auxiliary electronic and electrical equipment, a multi-channel power supply and control system for the hemodialysis machine based on high-frequency magnetic amplifiers has been developed and researched. The advantages of power switches based on high-frequency magnetic amplifiers in comparison with transistor switches, including in the construction of controlled power sources, are given. The principle of operation of the voltage regulator on high-frequency magnetic amplifiers is described. Theoretical and experimental oscillograms are given. Photographs of the experimental unit as well as an industrial sample of the multi-channel power supply and control system of the hemodialysis machine are provided. Their main technical characteristics are given. Conclusions to the conducted work are formulated. Carrying out the regeneration of the dialysis solution significantly reduces its costs – 2 liters of solution, which is suitable for use for 6 months, is enough for the operation of the device. Existing hemodialysis machines are a stationary open system using a single-use dialysis solution at a rate of up to 35 l/h, which ties the machine to stationary clinical conditions. Introducing feedback on the concentration of urea in the dialysis solution allows you to automate the blood purification procedure, as well as automatically complete hemodialysis at the necessary time, and also eliminates the dependence of the device on the conditions of the hospital.

PL

Do zasilania regeneratora, stabilizacji termicznej roztworu oraz zasilania pomocniczych urządzeń elektronicznych i elektrycznych opracowano i zbadano wielokanałowy układ zasilania i sterowania aparatu do hemodializy oparty na wzmacniaczach magnetycznych wysokiej częstotliwości. Przedstawiono zalety wyłączników mocy opartych na wzmacniaczach magnetycznych wysokiej częstotliwości w porównaniu z wyłącznikami tranzystorowymi, w tym w budowie sterowanych źródeł prądu. Opisano zasadę działania regulatora napięcia we wzmacniaczach magnetycznych wysokiej częstotliwości. Podano oscylogramy teoretyczne i eksperymentalne. Przedstawiono fotografie jednostki doświadczalnej oraz próbkę przemysłową wielokanałowego układu zasilania i sterowania aparatu do hemodializy. Podano ich główne parametry techniczne. Sformułowano wnioski z przeprowadzonej pracy. Przeprowadzenie regeneracji płynu do dializy znacząco obniża jego koszty – do pracy urządzenia wystarczają 2 litry płynu, który wystarcza na 6 miesięcy. Istniejące aparaty do hemodializy to stacjonarne systemy otwarte wykorzystujące roztwór do dializy jednorazowego użytku z szybkością do 35 l/h, co wiąże urządzenie ze stacjonarnymi warunkami klinicznymi. Wprowadzenie informacji zwrotnej o stężeniu mocznika w płynie dializacyjnym pozwala zautomatyzować procedurę oczyszczania krwi, a także automatycznie zakończyć hemodializę w wymaganym czasie, a także eliminuje zależność urządzenia od warunków panujących w szpitalu.

2

Diffusive solute transport in hollow fiber dialyzers is not affected by variable feed viscosity

Schneditz Daniel, Sauseng Notburga

Biocybernetics and Biomedical Engineering

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2022

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Vol. 42, no. 4

1112--1122

EN

Dialyzer clearance (K) for hemodialysis is usually predicted from the mass transfer area product (K0A) provided in manufacturer data sheets without accounting for elevated feed-viscosity when treating blood. The boundary layer model for mass transport across hollow fiber membranes, however, predicts an increase in mass transfer resistance (1/K0) and a decrease in K with increasing feed-viscosity. The effect of increased feed-side viscosity relative to baseline crystalloid viscosity on small solute K and 1/K0 was therefore examined in commercial high- (HF) and low-flux (LF) dialyzers in lab-bench studies using standard dialysis equipment in the normal operating range. Homogeneous colloid solutions and bovine plasma were used to simulate the range of relative viscosities (ηrel) and oncotic pressures expected under in-vivo conditions. Internal filtration (IF) was quantified by a mathematical model to obtain diffusive transport characteristics (K’, 1/K'0). An up to 5-fold increase in ηrel caused a small increase in K and a small decrease in 1/K0 in HF, but not in LF dialyzers. After correction for a small convective contribution by IF, K’ and 1/K'0 remained constant in both LF and HF dialyzers. Diffusive transport characteristics of commercial HF and LF dialyzers are independent of variable feed-side viscosity. This suggests an insignificant contribution of the feed-side boundary layer resistance in dialyzers optimized for operation in hemodialysis. Increasing the feed-side viscosity, however, increases the convective component of dialyzer solute transport because of IF. Diffusive dialyzer clearance predicted from the dialyzer K0A is independent of elevated feed-viscosity.

3

Modeling of insulin secretion and insulin mass balance during hemodialysis in patients with and without type 2 diabetes

Schneditz Daniel, Niemczyk Longin, Niemczyk Stanislaw

Biocybernetics and Biomedical Engineering

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2021

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Vol. 41, no. 2

391--401

EN

Background: The secretion, distribution, and elimination of insulin in response to a bolus of glucose injected during regular hemodialysis was modeled to quantify the intra-dialytic mass balance of glucose and insulin in patients without (D0) and with type 2 diabetes (D1). Methods: A two-compartment regional blood flow model with shared compartments and dynamics for glucose, insulin and c-peptide was used to identify parameters of insulin and c-peptide co-secretion, first- and second-pass hepatic insulin extraction, as well as insulin-independent and insulin-dependent glucose utilization. Experimental data from a previous study obtained in 21 D0 and 14 D1 were used to identify kinetic model parameters and the fractions of glucose and insulin removed by dialysis. Results: Modeled gains for insulin secretion (ß1 = 0.015 vs. 0.084 L/min, ß2 = 0.004 vs. 0.666 L) were lower in D1, resulting in a lower total insulin secretion (Mi = 6.40 vs. 38.0 nmol). Hepatic insulin extraction was high (Eihep = 0.558 vs. 0.638) and only slightly smaller in D1. The fraction of insulin removed by dialysis (Fid = 0.07 vs. 0.05) was small and comparable between D1 and D0. Modeled gains for insulin-dependent glucose uptake (γ = 0.38 vs. 1.34 L2/nmol/min) were lower whereas those for insulin-independent glucose uptake (λ = 0.14 vs. 0.067 L/min) were higher in D1. The fraction of glucose removed by dialysis (Fgd = 0.31 vs. 0.28) was higher in D1. Conclusion: Apart from expected differences in modeled secretion and glucose utilization in patients with and without diabetes an intravenous bolus of glucose causes only small differences in overall glucose and insulin balance during a typical hemodialysis treatment.

4

Modeling acid-base transport in hemodialyzers

Pietribiasi Mauro, Leypoldt John K.

Biocybernetics and Biomedical Engineering

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2021

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Vol. 41, no. 3

1150--1161

EN

One important objective of the hemodialysis treatment is the neutralization of interdialytic acid generation by transport of bicarbonate and other buffer bases from dialysis fluid to the patient via the hemodialyzer. Quantification of solute transport in hemodialyzers, in general, employs the concept of dialysance, a parameter that is often constant for given flow conditions, smaller than both the blood and dialysate flow rates, and independent of the solute concentration difference between blood and dialysate. This approach has been applied to bicarbonate transport in hemodialyzers, but such an approach neglects the transport of dissolved carbon dioxide (CO2) between dialysate and plasma, chemical equilibrium between bicarbonate and CO2, and other acid-base chemical reactions within blood. We describe a novel, one-dimensional model of bicarbonate and CO2 transport in hemodialyzers. The model equations were solved numerically and fitted to published data to estimate mass transfer-area coefficients for the relevant chemical species. Base excess in blood was assumed constant in the hemodialyzer. Simulations were performed for a dialysate bicarbonate concentration of 32 mEq/L at constant blood and dialysate flow rates and different plasma bicarbonate concentrations at the inlet of the hemodialyzer, both with and without CO2 transport. In the latter case, the bicarbonate mass transfer-area coefficient was adjusted to achieve the same total carbon dioxide transport. Calculated dialysance for CO2 exceeded the blood flow rate due to its conversion from bicarbonate in the hemodialyzer, and all calculated dialysances varied with inlet plasma bicarbonate concentration. We concluded that acid-base transport in hemodialyzers cannot be universally characterized by dialysances that are always less than the blood flow rate and independent of the concentration difference between dialysate and blood.

5

Comparison of two single-solute models of potassium kinetics during hemodialysis

Pietribiasi Mauro, Waniewski Jacek, Zaluska Wojciech, Wójcik-Zaluska Alicia, Leypoldt John K.

Biocybernetics and Biomedical Engineering

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2020

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Vol. 40, no. 3

938--949

EN

Optimal potassium removal in hemodialysis (HD) is an important but difficult to achieve goal, influenced by numerous factors. Two types of single-solute mathematical models have been previously proposed to assess potassium kinetics in HD: pseudo-one compartment ( p1) and two-compartment models (2c). We compared these two models in simulating potassium kinetics during HD sessions with different treatment settings. After estimation of unknown parameters via fitting to clinical data during 4 h sessions with a dialysate potassium of 2.6 ± 0.6 mmol/L, the models were used to simulate 4 HD sessions for each patient, resulting from the combination of session length (4 h vs. 8 h) and potassium dialysate concentration (2.6 vs. 0 mmol/L). The simulated potassium concentration profiles were similar under different treatment conditions, and predicted potassium removal during the treatments was 77 ± 24 mmol with the standard settings; both increases in session length and potassium dialysate to plasma concentration gradient resulted in a significant increase in potassium removed. Both models indicated similar minimum values of dialysate potassium concentration required to avoid post-HD hypokalemia: 1.18 ± 0.66 mmol/L for 4 h HD and 1.71 ± 0.52 mmol/L for 8 h HD. The models described similar kinetics for potassium during different combinations of treatment settings. Total removal of potassium and minimum dialysate concentration to avoid post-HD hypokalemia, were predicted without significant differences by both models. Although no model has a clear advantage in terms of describing clinical data, our analyses suggest that 2c might offer a better trade-off between physiological accuracy and over-parametrization.

6

A two-stage model of an arteriovenous fistula maturation process

Jodko Daniel M., Obidowski Damian S., Reorowicz Piotr, Jóźwik Krzysztof

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 2

139--153

EN

Purpose: An arteriovenous fistula has been a widely accepted vascular access for hemodialysis, however, a fistula maturation process is still not fully understood. In the short period of time, right after vein and artery shunting, the physical and biological changes take place mainly in the venous wall. A two-stage modeling method of arteriovenous fistula maturation process was proposed and presented. Methods: The first stage of the maturation was modeled with two-way coupled fluid structure interaction computer simulations. Whereas for the second, biological stage, a model was based on the change in the elasticity of the venous wall due to wall shear stress (WSS) modifications. Results: The relation between stress and radial and circumferential strain, based on Lame’s theory, makes possible to introduce a mathematical model defining modulus of elasticity, averaged WSS, and venous diameter as time functions. The presented model enables one to predict changes in the monitored parameters in the arteriovenous fistula taking place in the time longer than 90 days. Conclusions: We found that probably the majority of fistulas can be assessed to be mature too early, when the adequate blood flow rate is achieved but mean WSS still remains at the non-physiological level (>10 Pa).

7

Uzdatnianie wody do hemodializ

Pasieka Grzegorz

Instal

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2019

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nr 4

44--47

PL

Współczesna dializoterapia, a w szczególności nowoczesne techniki dializ wysoko-przepływowych wymagają zastosowania wody do dializ o odpowiedniej czystości chemicznej i mikrobiologicznej. W artykule omówiono przykładowy system oczyszczania wody do dializ przy zastosowaniu odwróconej osmozy.

EN

Contemporary hemodialysis, and in particular modern high-flow dialysis techniques, requires the use of dialysis water with appropriate chemical and microbiological purity. The article discusses an example of a water purification system for dialysis using reverse osmosis.

8

Zastosowanie termowizji w diagnostyce chorób naczyń u chorych hemodializowanych

Żyłka W., Gala-Błądzińska A.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

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2016

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Vol. 22, nr 3

121--129

PL

W pracy pokazano przydatność obserwacji termogramów rąk u chorych hemodializowanych w ocenie patologicznych zmian w zakresie unaczynienia rąk. Omówiono zasadę działania kamer termowizyjnych oraz ich zastosowanie w badaniach biomedycznych. Pokazano technikę termowizyjną jako dodatkowe nieinwazyjne narzędzie pozwalające na wyłonienie grupy chorych hemodializowanych szczególnie narażonych na powikłania naczyniowe. Zaobserwowano tendencje do obniżania się temperatury rąk chorych wraz z gorszymi parametrami gospodarki wapniowo fosforanowej oraz aterogennym profilem lipidowym. Badania przeprowadzono w grupie 35 chorych przewlekle hemodializowanych, a uzyskane dane porównano do wyników 22 zdrowych mężczyzn.

EN

The study shows the usefulness of the observation of thermographs of hands in hemodialysis patients in the evaluation of pathological changes in the vascularity of hands. The main principle of working of thermal imaging cameras and their application in biomedical researches were discussed. The thermographic technique was shown as an additional non-invasive tool to identify a group of hemodialysis patients who are particularly susceptible to vascular complications. It was observed the tendency to reduce the temperature of hands in patients with worse parameters of a calcium-phosphate metabolism and atherogenic lipid profile. The study was conducted in a group of 35 hemodialysis patients and the data was compared to results obtained in 22 healthy men.

9

Enzymy w chemii analitycznej

Koncki R.

Wiadomości Chemiczne

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2015

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[Z] 69, 9-10

653--670

EN

There are three main fields of modern analytical chemistry where enzymes are presented: (1) biorecognition, biosensing and biodetection schemes, especially important in case of biosensors, (2) enzymes as analytes, and (3) enzymes as markers in immune- and genoanalysis. These analytical fields could be illustrated by the research of bioanalytics group supervised by professor Stanisław Głąb.

10

Blood platelets apoptosis in hemodialyzed patients

Sobol A., Kamińska M., Walczyńska M., Stasiak M., Szymański J., Walkowiak M., Walkowiak B.

Engineering of Biomaterials

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2009

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Vol. 12, no. 89-91

29--30

EN

Blood platelet proteome of hemodialyzed uremic patients exhibits significant difference in comparison to the blood platelet proteome of healthy subjects. This alteration is manifested by the presence of high concentrations of low molecular peptides within the whole range of pI. Increased platelet apoptosis has been put forward as a possible cause of this phenomenon (1). The aim of the present research was to assess whether blood platelet populations from hemodialyzed uremic patients exhibit more binding sites for Annexin V (a marker of apoptosis) than control samples from healthy donors. Blood was obtained from uremic patients immediately before and after hemodialysis. At the same time samples from control healthy donors were also collected. Blood was anticoagulated with sodium citrate and was immediately exposed to propidium iodide, fluorescent labeled Annexin V and CD61 antibodies. The samples were incubated for 10 minutes in the dark and next the labeled samples were processed in a BectonDickinson FACScan flow cytofluorymeter. Our preliminary study was performed for 12 hemodialyzed patients, 13nondialyzed uremic patientsand 12 controls. It was found that the blood platelet population of hemodialyzed patients exhibited significantly higher level of fluorescence intensity attributed to Annexin V. Furthermore, this intensity was comparable before and after hemodialysis and was independent on patient age. The results support the hypothesis that blood platelet contact with artificial surfaces during the process of hemodialysys may be partially responsible for triggering blood platelet apoptosis.

11

Uproszczony przepływowy model hemodializy - porównanie z klasycznym modelem dwuprzedziałowym

Korohoda P.

Automatyka / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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2009

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T. 13, z. 3/1

1129-1140

PL

W artykule zaproponowano uproszczoną strukturę modelu przepływowego hemodializy, zbliżoną do klasycznego modelu dwuprzedziałowego. W celu przeprowadzenia obliczeń porównawczych umożliwiających ocenę przydatności nowego modelu opracowano metodykę pseudolosowego generowania danych symulujących zabieg dializy. Dla wytworzonego w ten sposób zbioru danych testowych, N — 1000 wykazano, iż oba modele - proponowany i klasyczny - wykazują podobną zdolność odtwarzania zadanych przebiegów stężeń. Dla opisanych wyżej danych wyznaczono zależność między najważniejszymi parametrami obu modeli, wykazując możliwość ich łatwego przeliczania. Wskazano jednak także na pewne różnice w przebiegach uzyskanych za pomocą obu modeli, co stanowi uzasadnienie dalszego badania modeli przepływowych.

EN

In the paper a simplified blood flow model of hemodialysis is sugested, being a modified version of the classical two-compartment model. A method of pseudorandom hemodialysis data generation has been designed to enable relevant comparative study of both models. For such test data, N = 1000, it has been shown that the flow model has very similar capability of modeling the concentration runs, as the classical two-compartment model. For the randomly generated data, the mutual relationship between the crucial model parameters has been shown. Such property makes the convertion between discussed models very simple. However, some differences in the runs obtained from both models were also indicated, which encourages further investigation of the blood-flow models.

12

Co kardiolog powinien wiedzieć o nefrologii?

Koscielniak K.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

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2008

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Vol. 14, nr 3

245-246

PL

Nefrologia jest dziedziną bardzo hermetyczną dla "nienefrologów". W Polsce dializuje się kilkanaście tysięcy pacjentów, wśród których około 90% stanowią chorzy leczeni hemodializą, a 10% - dializą otrzewnową [1]. Z tej populacji około 10-20% stale przebywa w oddziałach szpitalnych z powodu powikłań. Pacjenci z chorobami nerek są specyficzną, niejednorodną grupą chorych, charakteryzującą się odmienną epidemiologią, wysokim odsetkiem powikłań [2], mającą odmienne rokowania po takich samych procedurach terapeutycznych, jak "populacja nienefrologiczna", wymagającą specjalnego traktowania, innego interpretowania badań biochemicznych, odmienności leczenia [3].

13

Wpływ metody wyznaczania na wartość wskażnika dawki dializy Kt/V w warunkach klinicznych

Korohoda P., Pietrzyk J., Rumian R., Krawentek L., Miklaszewska M.

Pomiary Automatyka Kontrola

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2007

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R. 53, nr 9 bis

440--443

PL

Frakcjonowany klirens objętości dystrybucji (Kt/V) jest jednym z parametrów mających istotne znaczenie rokownicze u chorych hemodializowanych, dializowanych otrzewnowo oraz w okresie przeddializacyjnym. U pacjentów hemodializowanych wskaźnik może był wyliczany uproszczonymi wzorami, z modelu jednoprzedziałowego (wg Gotcha lub Lowriego), za pomoca estymacji (wg Daugirdasa) lub z korekt modelu 1-przedziałowego do 2-przedziałowego (wg Tattersaala lub Maduella). W pracy opisano kolejno najważniejsze problemy związane z wyliczaniem Kt/V, a na końcu porównano wartości wyliczone za pomocą wybranych zależności, na podstawie empirycznie uzyskanych danych z modelowania 91 pacjento-sesji dializacyjnych. Wyliczono wartość Kt/V wg różnych wzorów, po czym dokonano analizy zmienności. Wyniki analizy zwracają uwagę na adekwatność poszczególnych wzorów oraz możliwości praktycznego ich stosowania do oceny dawki dializy.

EN

Fractional urea distribution volume clearance (Kt/V) remains important dialysis adequacy parameter and prognostic factor in predialysis, hemo- and peridonealy dialysed patients. For Kt/V calculations simplified formulas (by Gotch or Lowrie), employing single-pool model, can be applied. Mathematical corrections can convert the spKt/V value do double-pool model, according to Daugirdas, Tattersaal and Maduell formulas. The paper describes in details main problems related with dpKt/V calculations. In the clinical study, the data obtained in 91 HD sessions allowed for estimation of spKt/V, eqKt/V and by Daugirdas, Tattersaal and Maduell methods, respectively. Analysis of variation was performed. The results of the above analysis draw our attention to adequacy of the particular formulas and their further, practical application for dialysis dose assessment.

14

High-hydrophilic membranes for dialysis and hemodialysis

Suberlyak O., Melnyk J., Baran N.

Engineering of Biomaterials

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2007

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Vol. 10, no. 63-64

18-19

15

Analiza wrażliwościowa wyznaczanego optymalizacyjnie klirensu komórkowego w modelu dwuprzedziałowym

Korohoda P.

Automatyka / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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2006

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T. 10, z. 3

63-69

PL

Artykuł dotyczy modelowania kinetycznego mocznika, stosowanego do wspomagania procesu leczenia hemodializą. Prace zmierzające do wprowadzenia do praktyki klinicznej modelu dwuprzedziałowego napotykają barierę braku danych liczbowych dla kluczowego parametru, jakim jest klirens komórkowy, Kc. Wyznaczanie tej wartości poprzez procedury optymalizujące metodą modelu strojonego na podstawie odpowiedniego zestawu danych pomiarowych musi być realizowane przy znajomości wrażliwości na zmiany w tych danych, wynikające z nieuniknionych błędów pomiarowych. W artykule opisano metodę szacowania wrażliwości parametru Kc na zmiany wartości parametrów traktowanych jako dane wejściowe procedury optymalizującej. Przedstawiono również przykład obliczeniowy, bazujący na typowych wartościach, umożliwiający wskazanie parametrów, których wartości muszą być mierzone ze szczególną precyzją. Zastosowanie opisanej metody umożliwi odróżnienie zmian w wyznaczonych wartościach parametru Kc świadczących o istotnych zjawiskach od zmian wynikających z niedokładności pomiarów parametrów wejściowych.

EN

The paper considers the kinetic urea modelling, a tool used in the haemodialysis treatment. The efforts to introduce the two-compartmental model to the practical applications are mitigated by the lack of numerical value for the cellular clearance, Kc, being the crucial parameter of this model. The optimisation procedure, utilising the adjusted model technique to assess the Kc value, should be applied with the knowledge about relevant sensitivity of the resulting values to the changes in the input parameters. The changes that result from the inevitable measurement errors. In the paper a method of evaluating the required sensitivity values is described and a computational example based on the typical values is provided. The obtained results may be used to indicate the input parameters which must be measured with particular care. Application of the described procedure should provide arguments to recognise if the differences between the obtained Kc values result from inaccuracy of the input values or indicate the important phenomena.

16

Mathematical modeling of renal replacement therapies

Gałach M., Weryński A.

Biocybernetics and Biomedical Engineering

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2004

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Vol. 24, no. 4

3-18

EN

Optimization of dialysis needs methods for quantitative assessment of hydraulic and oncotic pressure well as fluid and solute transport in body compartments. A mathematical model describing dynamics of these quantities during dialysis is presented. During dialysis, the blood volume often decreases; therefore, model includes the cardiovascular system. Mechanisms which react to blood volume loses are also taken into account. The purpose of this model is to serve as a decision support system for selection of "optimal" treatment options for particular patient.

17

Modeling of urea concentration in serum after hemodialysis

Nowak P., Szczepaniak P. S., Filutowicz J., Ojha P. C.

Journal of Medical Informatics & Technologies

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2001

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Vol. 2, Part. 2

SN9--SN14

EN

The paper presents a general review of two approaches to modeling of urea concentration in serum after hemodialysis. The first approach is a well-established classic method, widely accepted by medical staff dealing with practical nephrology. The other one utilises the power of artificial neural networks, which is a novel application to that field. Unlike classic models that base on theoretical investigation, this technique uses only a number of data from previous treatment to construct a model through so called learning from examples.

18

Adsorption of fibrinogen and albumin in a cellulose membrane for hemodialysis

De Reytere H. A., Boonaert C. J. P., Rouxhet P. G., Dewez J.-L.

Inżynieria Biomateriałów

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2001

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R. 4, nr 17-19

14-14