Frantisek Lopot - Academia.edu (original) (raw)
Papers by Frantisek Lopot
The International Journal of Artificial Organs, 2002
The article suggests a novel method for quantitative determination of optimal dry weight in dialy... more The article suggests a novel method for quantitative determination of optimal dry weight in dialysis patient based on their extracellular volume (ECV) to total body water (TBW) ratio and its relation to age. Values of ECV and TBW are evaluated by means of whole body multifrequency bioimpedometry. In an effort to find a suitable marker of hydration status in an individual from bioimpedance data, significant correlation has been found between ECV/TBW ratio and age in health. Assuming that all excess fluid in dialysis patients is stored exclusively in ECV and that distribution of their TBW at the state of optimal dry weight corresponds to that of a healthy person of the same age, the pre-dialysis ECV/TBW could be used for quantitative determination of optimal dry weight and/or of the ultrafiltration to reach this weight. Practical bioimpedance measurement of ECV/TBW in a group of dialysis patients both pre- and post-dialysis confirmed both above assumptions, i.e. nearly exclusively ext...
Biotechnology in Renal Replacement Therapy
Casopís lékar̆ů c̆eských, Jan 23, 1998
For evaluation of the adequacy of peritoneal and haemodialyzation treatment the BP/V index is use... more For evaluation of the adequacy of peritoneal and haemodialyzation treatment the BP/V index is used. In the literature there is so far no uniform view on the procedure of calculation. The objective was to test whether and to what extent the results of different procedures differ. The authors demonstrated that the method of calculation of this index has a marked impact on the result. The greatest discrepancy was due to differences in the distribution volume of urea (or total body water) where the mean difference was 10% of the absolute value. Also the procedure used to assess the residual renal function can influence the result. Differences due to the method of collection of the dialysate for assessment of the urea concentration are insignificant. The mean difference between the maximal and minimal BP/V index, when different methods of calculation are used, was in the same patient 0.45, which is cca 25% of the total value. The BP/V index must be assessed always by the same method with...
Contributions to Nephrology
Central venous catheter (CVC)-related problems, risks and safety hazards are partly caused by dif... more Central venous catheter (CVC)-related problems, risks and safety hazards are partly caused by different characteristics of the CVC-based access and their performance features. This chapter covers those issues in a chronological order, from factors related to the choice of the CVC, insertion site and insertion procedure itself, over those associated with CVC use and their monitoring up to safety hazards of interventional procedures. Not discussed are CVC infections as they are covered in a separate chapter in this book.
EDTNA-ERCA Journal, 2003
SUMMARYIn order to deliver a specific dialysis dose (Kt/V) to all patients, their product Kt (ure... more SUMMARYIn order to deliver a specific dialysis dose (Kt/V) to all patients, their product Kt (urea clearance K multiplied by dialysis time t) should be individually adjusted according to total body water (V) of each patient. With dialysis time being fixed in most centres for organisational reasons, such individualisation can be accomplished by individually set blood flow (QB). For a given t, the value of QB also defines the magnitude of the cumulative blood volume (VB=QB*t), i.e. the volume of blood perfused through the dialyser during the whole dialysis time. VB is displayed by every contemporary dialysis machine but not used. The aim of this work was to derive an easy to use approach to QB individualisation based on patient's body weight and dialysis time to obtain a desired Kt/V value which would also be easy to check after dialysis by looking at the obtained VB value.Statistically significant correlation was found between the QB‐based Kt/V estimation and Kt/V determined by t...
EDTNA-ERCA Journal, 2003
SUMMARYAccess dysfunction presents a risk for haemodialysis patients and is costly for health car... more SUMMARYAccess dysfunction presents a risk for haemodialysis patients and is costly for health care providers. Regular vascular access quality (VAQ) monitoring enables the detection of adverse access conditions early allowing timely interventions, which will presumably be less invasive, more successful and cheaper. This paper reviews all currently used assessment parameters: dynamic and static pressures, recirculation and blood flow through the access — and analyses pros and cons of each of them. Based on this overview it is concluded that access flow monitoring should be the method of choice, possibly combined with monitoring of another parameter to further enlarge diagnostic possibilities of the monitoring. The VAQ monitoring system developed and used currently in the author's dialysis centre is briefly described as an example. The issue of access flow related to haemodynamics is briefly mentioned. With the introduction of any VAQ monitoring system, one has to acknowledge a cha...
Artificial Organs, 1995
Traditionally Gibbs-Donnan coefficients based on the mean charge of plasma proteins are used as t... more Traditionally Gibbs-Donnan coefficients based on the mean charge of plasma proteins are used as the only correction factor in equations describing sodium transport across the dialyzer membrane. This ignores the possible impact of the membrane material. Correction coefficients (CC) of the whole dialyzer were measured during in vivo dialysis as a quotient of dialysate to plasma sodium in an equilibrated state for different membrane materials used in commercially available dialyzers. Their mean value and correlation with total plasma protein content (TPP) were evaluated. CC for the six materials evaluated differed both in the intercept and slope of the regression line CC versus TPP: Cuprophan 1: CC = 1.0253-0.00017 x TPP; Hemophan I: CC = 1.119-0.00175 x TPP; Hemophan 2: CC = 1.095-0.001 1 I X TPP;
Vnitřní lékařství, Dec 1, 2016
Nejčastější příčinou úmrtí u pacientů s chronickým selháním ledvin léčených dialýzou jsou kardiov... more Nejčastější příčinou úmrtí u pacientů s chronickým selháním ledvin léčených dialýzou jsou kardiovaskulární problémy. Ty jsou do značné míry důsledkem neadekvátního řízení tekutinové bilance, pro které je klíčovým faktorem správný odhad míry převodnění (OH-overhydration). Pro zpřesnění jeho odhadu, dosud dělaného většinou na základě klinických příznaků, byla vyvinuta celá řada metod od různých antropometrických vzorců, přes biochemické markery až po přístrojové techniky jako např. ultrasonografické měření dolní duté žíly, echokardiografie, kontinuální měření změn krevního objemu a další. Mezi ně již několik desítek let patří bioimpedanční měření. Bioimpedometrie, resp. bioimpedanční analýza (BIA) je založena na faktu, že odpor, který živé tkáně kladou průchodu elektrického proudu, výrazně závisí na míře jejich hydratace. To metodu přímo předurčuje k hodnocení hydratace a jejich změn. Zjištění, že proudy nižších frekvencí procházejí pouze extracelulární tekutinou a teprve proudy vyšší frekvence i intracelulárním prostorem, umožňuje dále odlišit extracelulární a intracelulární prostor (extra/intracellular volume-ECV/ICV). Je-li tělo nebo jeho měřená část brána jako prostorový (objemový) vodič, lze z hodnot impedance a základních tělesných rozměrů spočítat objemy jednotlivých kompartmentů tělesných tekutin, resp. celkovou těles
Ndt Plus, Mar 23, 2015
Background. This article summarizes the 2012 European Renal Association-European Dialysis and Tra... more Background. This article summarizes the 2012 European Renal Association-European Dialysis and Transplant Association Registry Annual Report (available at www.era-edta-reg.org) with a specific focus on older patients (defined as ≥65 years). Methods. Data provided by 45 national or regional renal registries in 30 countries in Europe and bordering the Mediterranean Sea were used. Individual patient level data were received from 31 renal registries, whereas 14 renal registries contributed data in an aggregated form. The incidence, prevalence and survival probabilities of patients with end-stage renal disease (ESRD) receiving renal replacement therapy (RRT) and renal transplantation rates for 2012 are presented. Results. In 2012, the overall unadjusted incidence rate of patients with ESRD receiving RRT was 109.6 per million population (pmp) (n = 69 035), ranging from 219.9 pmp in Portugal to 24.2 pmp in Montenegro. The proportion of incident patients ≥75 years varied from 15 to 44% between countries. The overall unadjusted prevalence on 31 December 2012 was 716.7 pmp (n = 451 270), ranging from 1670.2 pmp in Portugal to 146.7 pmp in the Ukraine. The proportion of prevalent patients ≥75 years varied from 11 to 32% between countries. The overall renal transplantation rate in 2012 was 28.3 pmp (n = 15 673), with the highest rate seen in the Spanish region of Catalonia. The proportion of patients ≥65 years receiving a transplant ranged from 0 to 35%. Five-year adjusted survival for all RRT patients was 59.7% (95% confidence interval, CI: 59.3-60.0) which fell to 39.3% (95% CI: 38.7-39.9) in patients 65-74 years and 21.3% (95% CI: 20.8-21.9) in patients ≥75 years.
The International Journal of Artificial Organs, 1997
The recently introduced continuous blood volume monitoring (CBVM) technique enables real time obs... more The recently introduced continuous blood volume monitoring (CBVM) technique enables real time observation of the blood volume (BV) response to ultrafiltration. This response differs quite widely among patients even under otherwise comparable conditions. Assessing the clinical recordings of over 100 CBVM measurements, identification of a static and a dynamic component of the overall BV reduction was made. Computational analysis of the factors that influence BV response variability was then performed by means of a three-pool model of sodium, potassium, and urea kinetics with the following results. The blood volume profile contains clinically highly interesting yet cummulative information. Except for the small change and flat BV profiles the static component is predominant. From the external factors, the static component of BV reduction during hemodialysis is influenced by the total ultrafiltered volume and by the degree of overhydration. From the patient's internal factors, compli...
Home Hemodialysis International, 1998
Although the unphysiology of the intermittently applied dialysis treatment was a concern of the d... more Although the unphysiology of the intermittently applied dialysis treatment was a concern of the dialysis pioneers, the development of any mathematical theory of treatment unphysiology and its quantification was not attempted until the end of the 1980s. This paper suggests that the conventional urea kinetic modeling (UKM) be complemented with a new parameter, the time‐averaged deviation (TAD). TAD is the mean plasma urea concentration fluctuation around its mean value (time‐averaged concentration, TAC). The value of TAD increases with a decreasing number of dialysis treatments per week, that is, with increasing dialysis unphysiology. Thus it can be used to quantify this until now only intuitively assessed treatment parameter. Status of a patient on any given treatment schedule can be characterized by a point on the TAC/TAD plot. Sensitivity analysis performed using the TAC/TAD plot offers insight into the influence of different patient‐ and treatment‐related parameters on the point l...
Artificial Organs, 1986
: The aim of this study was to confirm or to reject whether plasma concentrations of individual f... more : The aim of this study was to confirm or to reject whether plasma concentrations of individual fractions of middle molecular weight substances can become parameters for an adequate dialysis treatment and whether there exists a relation between that and some symptoms and signs in patients on regular dialysis. No changes in clinical condition, plasma concentration of middle molecules, or metabolic state after 5 years of short‐time dialysis schedule were established. No difference was found in the plasma concentration of middle molecules after 6 months of continuous ambulatory peritoneal dialysis and in patients undergoing hemodialysis treatment. There was also no difference in glomerular filtration rate, blood urea concentration, dialysis index, and duration of regular dialysis treatment in patients with a middle molecular fraction 2 level lower and higher than 5.5 U/L. Elimination of fractions 2–4 and 6 by a 1‐m2 Cuprophan coil dialyzer was similar to the elimination of creatinine. Only patients with acute respiratory infection had a fraction 2 higher than controls. Neither conventional parameters nor plasma concentrations of middle molecules can be indicators of an adequate dialysis. The well‐being of patients and their metabolic state are the only criteria.
EDTNA-ERCA Journal, 2001
SummaryVascular access quality monitoring by means of vascular access blood flow (QVA) evaluated ... more SummaryVascular access quality monitoring by means of vascular access blood flow (QVA) evaluated from automated thermodilutional measurement of recirculation with reverse needle position is described. This method provides significant advantages over conventional methods based on simple monitoring of pressures in the extracorporeal circuit and/or measurement of recirculation with normal needle position.AQVA evaluation protocol was developed and introduced into the system of primary nursing. The QVA values were found independent of the extracorporeal blood flow used during the recirculation measurement. QVA values from below 200 ml/min to over 2 l/min were seen. In general, lower values were found in diabetics compared to non‐diabetics and in females compared to males. While blood flow below 600 ml/min is considered risky for synthetic vascular grafts, native AV‐fistulae seem to remain stable and patent at a flow of 400 ml/min or even below.The method is able to detect erroneous needl...
Hemodiafiltration (HDF) adds convective elimination of middle molecules (MM), proportional to fil... more Hemodiafiltration (HDF) adds convective elimination of middle molecules (MM), proportional to filtered volume (Vconv) on the top of diffusion-based elimination of small molecules (SM) by conventional hemodialysis (HD). Studies, both observational and randomized controlled ones, performed so far generally indicated positive impact of higher Vconv on all-cause mortality in HDF patients, although the magnitude of Vconv at which HDF becomes apparently superior to HD differed widely among the studies. Also the issue of a suitable anthropometric parameter by which the Vconv should be normalized has not yet been solved. Data from the ESHOL study seems to indicate that patient´s body surface area (BSA) could well be used for this—mortality was decreasing with increasing Vconv/BSA with a bottom plateau starting at about 15 L/m2. We have therefore devised a formula and a graph for determination of Vconv which fulfils the requirement Vconv/BSA= 15. Assuming maximum feasible and safe filtration...
Shortly after intermittent haemodialysis became established treatment of chronic renal failure, t... more Shortly after intermittent haemodialysis became established treatment of chronic renal failure, the first wearable artificial kidney (WAK) device projected or even constructed to solve the problem of intermittent treatment unphysiology. Successful development of hollow fibres enabled construction of a sufficiently small dialyzer to be worn and recirculation of dialysate through a sorbent cartridge lead to tremendous drop in dialysate volumes needed. Tested were WAK devices based both on haemodialysis (HD) or on haemofiltration (HF) (after highly permeable membranes became available) as well as on peritoneal dialysis (PD). Later, some other techniques and processes appeared in armamentarium of WAK designers, such as charged membranes, electrodialysis, nanotechnological processes enabling to create membranes with solute-specific pores. Also a few hybride constructions appeared during the last decade using membranes coated with tubular epithelial cells to mimic tubular resorption of bi...
Hemodialysis International
Journal of nephrology
Intradialytic morbid events (IMEs) during haemodialysis (HD), including symptomatic hypotension, ... more Intradialytic morbid events (IMEs) during haemodialysis (HD), including symptomatic hypotension, are related to ultrafiltration (UF)-induced hypovolaemia. Blood volume monitoring and automatic feedback control of the UF rate were developed to limit the extent of hypovolaemia during dialysis. The present study investigated the effect of blood volume (BV)-controlled UF on the incidence of HD treatments with IMEs. This prospective randomised crossover study included hypotension-prone patients, characterised by occurrence of IMEs in at least 33% of HD treatments during a 6-week screening phase. These patients underwent 2 treatment phases, each lasting 6 weeks, in randomised order. Each patient served as their own control, treated with standard HD in one phase and with BV-controlled UF in the other phase. Thirty-four patients from 9 HD centres were enrolled; 26 could be included in the analysis population. In comparison with standard HD, BV-controlled UF reduced the percentage of HD sess...
Nephrology news & issues, 2001
The quality of water used for dialysis is not subject to any mandatory regulations in most Europe... more The quality of water used for dialysis is not subject to any mandatory regulations in most European countries. A survey of haemodialysis facilities in 14 countries carried out by the European Dialysis and Transplant Nurses Association/European Renal Care Association (EDTNA/ERCA) showed that the majority of centres aimed to meet the requirements of the European Pharmacopoeia, but only 50% carried out tests to check compliance. The wide variation in policies for maintaining and monitoring the equipment and the distribution system indicates that guidelines for water treatment are urgently needed in Europe.
The International Journal of Artificial Organs, 2002
The article suggests a novel method for quantitative determination of optimal dry weight in dialy... more The article suggests a novel method for quantitative determination of optimal dry weight in dialysis patient based on their extracellular volume (ECV) to total body water (TBW) ratio and its relation to age. Values of ECV and TBW are evaluated by means of whole body multifrequency bioimpedometry. In an effort to find a suitable marker of hydration status in an individual from bioimpedance data, significant correlation has been found between ECV/TBW ratio and age in health. Assuming that all excess fluid in dialysis patients is stored exclusively in ECV and that distribution of their TBW at the state of optimal dry weight corresponds to that of a healthy person of the same age, the pre-dialysis ECV/TBW could be used for quantitative determination of optimal dry weight and/or of the ultrafiltration to reach this weight. Practical bioimpedance measurement of ECV/TBW in a group of dialysis patients both pre- and post-dialysis confirmed both above assumptions, i.e. nearly exclusively ext...
Biotechnology in Renal Replacement Therapy
Casopís lékar̆ů c̆eských, Jan 23, 1998
For evaluation of the adequacy of peritoneal and haemodialyzation treatment the BP/V index is use... more For evaluation of the adequacy of peritoneal and haemodialyzation treatment the BP/V index is used. In the literature there is so far no uniform view on the procedure of calculation. The objective was to test whether and to what extent the results of different procedures differ. The authors demonstrated that the method of calculation of this index has a marked impact on the result. The greatest discrepancy was due to differences in the distribution volume of urea (or total body water) where the mean difference was 10% of the absolute value. Also the procedure used to assess the residual renal function can influence the result. Differences due to the method of collection of the dialysate for assessment of the urea concentration are insignificant. The mean difference between the maximal and minimal BP/V index, when different methods of calculation are used, was in the same patient 0.45, which is cca 25% of the total value. The BP/V index must be assessed always by the same method with...
Contributions to Nephrology
Central venous catheter (CVC)-related problems, risks and safety hazards are partly caused by dif... more Central venous catheter (CVC)-related problems, risks and safety hazards are partly caused by different characteristics of the CVC-based access and their performance features. This chapter covers those issues in a chronological order, from factors related to the choice of the CVC, insertion site and insertion procedure itself, over those associated with CVC use and their monitoring up to safety hazards of interventional procedures. Not discussed are CVC infections as they are covered in a separate chapter in this book.
EDTNA-ERCA Journal, 2003
SUMMARYIn order to deliver a specific dialysis dose (Kt/V) to all patients, their product Kt (ure... more SUMMARYIn order to deliver a specific dialysis dose (Kt/V) to all patients, their product Kt (urea clearance K multiplied by dialysis time t) should be individually adjusted according to total body water (V) of each patient. With dialysis time being fixed in most centres for organisational reasons, such individualisation can be accomplished by individually set blood flow (QB). For a given t, the value of QB also defines the magnitude of the cumulative blood volume (VB=QB*t), i.e. the volume of blood perfused through the dialyser during the whole dialysis time. VB is displayed by every contemporary dialysis machine but not used. The aim of this work was to derive an easy to use approach to QB individualisation based on patient's body weight and dialysis time to obtain a desired Kt/V value which would also be easy to check after dialysis by looking at the obtained VB value.Statistically significant correlation was found between the QB‐based Kt/V estimation and Kt/V determined by t...
EDTNA-ERCA Journal, 2003
SUMMARYAccess dysfunction presents a risk for haemodialysis patients and is costly for health car... more SUMMARYAccess dysfunction presents a risk for haemodialysis patients and is costly for health care providers. Regular vascular access quality (VAQ) monitoring enables the detection of adverse access conditions early allowing timely interventions, which will presumably be less invasive, more successful and cheaper. This paper reviews all currently used assessment parameters: dynamic and static pressures, recirculation and blood flow through the access — and analyses pros and cons of each of them. Based on this overview it is concluded that access flow monitoring should be the method of choice, possibly combined with monitoring of another parameter to further enlarge diagnostic possibilities of the monitoring. The VAQ monitoring system developed and used currently in the author's dialysis centre is briefly described as an example. The issue of access flow related to haemodynamics is briefly mentioned. With the introduction of any VAQ monitoring system, one has to acknowledge a cha...
Artificial Organs, 1995
Traditionally Gibbs-Donnan coefficients based on the mean charge of plasma proteins are used as t... more Traditionally Gibbs-Donnan coefficients based on the mean charge of plasma proteins are used as the only correction factor in equations describing sodium transport across the dialyzer membrane. This ignores the possible impact of the membrane material. Correction coefficients (CC) of the whole dialyzer were measured during in vivo dialysis as a quotient of dialysate to plasma sodium in an equilibrated state for different membrane materials used in commercially available dialyzers. Their mean value and correlation with total plasma protein content (TPP) were evaluated. CC for the six materials evaluated differed both in the intercept and slope of the regression line CC versus TPP: Cuprophan 1: CC = 1.0253-0.00017 x TPP; Hemophan I: CC = 1.119-0.00175 x TPP; Hemophan 2: CC = 1.095-0.001 1 I X TPP;
Vnitřní lékařství, Dec 1, 2016
Nejčastější příčinou úmrtí u pacientů s chronickým selháním ledvin léčených dialýzou jsou kardiov... more Nejčastější příčinou úmrtí u pacientů s chronickým selháním ledvin léčených dialýzou jsou kardiovaskulární problémy. Ty jsou do značné míry důsledkem neadekvátního řízení tekutinové bilance, pro které je klíčovým faktorem správný odhad míry převodnění (OH-overhydration). Pro zpřesnění jeho odhadu, dosud dělaného většinou na základě klinických příznaků, byla vyvinuta celá řada metod od různých antropometrických vzorců, přes biochemické markery až po přístrojové techniky jako např. ultrasonografické měření dolní duté žíly, echokardiografie, kontinuální měření změn krevního objemu a další. Mezi ně již několik desítek let patří bioimpedanční měření. Bioimpedometrie, resp. bioimpedanční analýza (BIA) je založena na faktu, že odpor, který živé tkáně kladou průchodu elektrického proudu, výrazně závisí na míře jejich hydratace. To metodu přímo předurčuje k hodnocení hydratace a jejich změn. Zjištění, že proudy nižších frekvencí procházejí pouze extracelulární tekutinou a teprve proudy vyšší frekvence i intracelulárním prostorem, umožňuje dále odlišit extracelulární a intracelulární prostor (extra/intracellular volume-ECV/ICV). Je-li tělo nebo jeho měřená část brána jako prostorový (objemový) vodič, lze z hodnot impedance a základních tělesných rozměrů spočítat objemy jednotlivých kompartmentů tělesných tekutin, resp. celkovou těles
Ndt Plus, Mar 23, 2015
Background. This article summarizes the 2012 European Renal Association-European Dialysis and Tra... more Background. This article summarizes the 2012 European Renal Association-European Dialysis and Transplant Association Registry Annual Report (available at www.era-edta-reg.org) with a specific focus on older patients (defined as ≥65 years). Methods. Data provided by 45 national or regional renal registries in 30 countries in Europe and bordering the Mediterranean Sea were used. Individual patient level data were received from 31 renal registries, whereas 14 renal registries contributed data in an aggregated form. The incidence, prevalence and survival probabilities of patients with end-stage renal disease (ESRD) receiving renal replacement therapy (RRT) and renal transplantation rates for 2012 are presented. Results. In 2012, the overall unadjusted incidence rate of patients with ESRD receiving RRT was 109.6 per million population (pmp) (n = 69 035), ranging from 219.9 pmp in Portugal to 24.2 pmp in Montenegro. The proportion of incident patients ≥75 years varied from 15 to 44% between countries. The overall unadjusted prevalence on 31 December 2012 was 716.7 pmp (n = 451 270), ranging from 1670.2 pmp in Portugal to 146.7 pmp in the Ukraine. The proportion of prevalent patients ≥75 years varied from 11 to 32% between countries. The overall renal transplantation rate in 2012 was 28.3 pmp (n = 15 673), with the highest rate seen in the Spanish region of Catalonia. The proportion of patients ≥65 years receiving a transplant ranged from 0 to 35%. Five-year adjusted survival for all RRT patients was 59.7% (95% confidence interval, CI: 59.3-60.0) which fell to 39.3% (95% CI: 38.7-39.9) in patients 65-74 years and 21.3% (95% CI: 20.8-21.9) in patients ≥75 years.
The International Journal of Artificial Organs, 1997
The recently introduced continuous blood volume monitoring (CBVM) technique enables real time obs... more The recently introduced continuous blood volume monitoring (CBVM) technique enables real time observation of the blood volume (BV) response to ultrafiltration. This response differs quite widely among patients even under otherwise comparable conditions. Assessing the clinical recordings of over 100 CBVM measurements, identification of a static and a dynamic component of the overall BV reduction was made. Computational analysis of the factors that influence BV response variability was then performed by means of a three-pool model of sodium, potassium, and urea kinetics with the following results. The blood volume profile contains clinically highly interesting yet cummulative information. Except for the small change and flat BV profiles the static component is predominant. From the external factors, the static component of BV reduction during hemodialysis is influenced by the total ultrafiltered volume and by the degree of overhydration. From the patient's internal factors, compli...
Home Hemodialysis International, 1998
Although the unphysiology of the intermittently applied dialysis treatment was a concern of the d... more Although the unphysiology of the intermittently applied dialysis treatment was a concern of the dialysis pioneers, the development of any mathematical theory of treatment unphysiology and its quantification was not attempted until the end of the 1980s. This paper suggests that the conventional urea kinetic modeling (UKM) be complemented with a new parameter, the time‐averaged deviation (TAD). TAD is the mean plasma urea concentration fluctuation around its mean value (time‐averaged concentration, TAC). The value of TAD increases with a decreasing number of dialysis treatments per week, that is, with increasing dialysis unphysiology. Thus it can be used to quantify this until now only intuitively assessed treatment parameter. Status of a patient on any given treatment schedule can be characterized by a point on the TAC/TAD plot. Sensitivity analysis performed using the TAC/TAD plot offers insight into the influence of different patient‐ and treatment‐related parameters on the point l...
Artificial Organs, 1986
: The aim of this study was to confirm or to reject whether plasma concentrations of individual f... more : The aim of this study was to confirm or to reject whether plasma concentrations of individual fractions of middle molecular weight substances can become parameters for an adequate dialysis treatment and whether there exists a relation between that and some symptoms and signs in patients on regular dialysis. No changes in clinical condition, plasma concentration of middle molecules, or metabolic state after 5 years of short‐time dialysis schedule were established. No difference was found in the plasma concentration of middle molecules after 6 months of continuous ambulatory peritoneal dialysis and in patients undergoing hemodialysis treatment. There was also no difference in glomerular filtration rate, blood urea concentration, dialysis index, and duration of regular dialysis treatment in patients with a middle molecular fraction 2 level lower and higher than 5.5 U/L. Elimination of fractions 2–4 and 6 by a 1‐m2 Cuprophan coil dialyzer was similar to the elimination of creatinine. Only patients with acute respiratory infection had a fraction 2 higher than controls. Neither conventional parameters nor plasma concentrations of middle molecules can be indicators of an adequate dialysis. The well‐being of patients and their metabolic state are the only criteria.
EDTNA-ERCA Journal, 2001
SummaryVascular access quality monitoring by means of vascular access blood flow (QVA) evaluated ... more SummaryVascular access quality monitoring by means of vascular access blood flow (QVA) evaluated from automated thermodilutional measurement of recirculation with reverse needle position is described. This method provides significant advantages over conventional methods based on simple monitoring of pressures in the extracorporeal circuit and/or measurement of recirculation with normal needle position.AQVA evaluation protocol was developed and introduced into the system of primary nursing. The QVA values were found independent of the extracorporeal blood flow used during the recirculation measurement. QVA values from below 200 ml/min to over 2 l/min were seen. In general, lower values were found in diabetics compared to non‐diabetics and in females compared to males. While blood flow below 600 ml/min is considered risky for synthetic vascular grafts, native AV‐fistulae seem to remain stable and patent at a flow of 400 ml/min or even below.The method is able to detect erroneous needl...
Hemodiafiltration (HDF) adds convective elimination of middle molecules (MM), proportional to fil... more Hemodiafiltration (HDF) adds convective elimination of middle molecules (MM), proportional to filtered volume (Vconv) on the top of diffusion-based elimination of small molecules (SM) by conventional hemodialysis (HD). Studies, both observational and randomized controlled ones, performed so far generally indicated positive impact of higher Vconv on all-cause mortality in HDF patients, although the magnitude of Vconv at which HDF becomes apparently superior to HD differed widely among the studies. Also the issue of a suitable anthropometric parameter by which the Vconv should be normalized has not yet been solved. Data from the ESHOL study seems to indicate that patient´s body surface area (BSA) could well be used for this—mortality was decreasing with increasing Vconv/BSA with a bottom plateau starting at about 15 L/m2. We have therefore devised a formula and a graph for determination of Vconv which fulfils the requirement Vconv/BSA= 15. Assuming maximum feasible and safe filtration...
Shortly after intermittent haemodialysis became established treatment of chronic renal failure, t... more Shortly after intermittent haemodialysis became established treatment of chronic renal failure, the first wearable artificial kidney (WAK) device projected or even constructed to solve the problem of intermittent treatment unphysiology. Successful development of hollow fibres enabled construction of a sufficiently small dialyzer to be worn and recirculation of dialysate through a sorbent cartridge lead to tremendous drop in dialysate volumes needed. Tested were WAK devices based both on haemodialysis (HD) or on haemofiltration (HF) (after highly permeable membranes became available) as well as on peritoneal dialysis (PD). Later, some other techniques and processes appeared in armamentarium of WAK designers, such as charged membranes, electrodialysis, nanotechnological processes enabling to create membranes with solute-specific pores. Also a few hybride constructions appeared during the last decade using membranes coated with tubular epithelial cells to mimic tubular resorption of bi...
Hemodialysis International
Journal of nephrology
Intradialytic morbid events (IMEs) during haemodialysis (HD), including symptomatic hypotension, ... more Intradialytic morbid events (IMEs) during haemodialysis (HD), including symptomatic hypotension, are related to ultrafiltration (UF)-induced hypovolaemia. Blood volume monitoring and automatic feedback control of the UF rate were developed to limit the extent of hypovolaemia during dialysis. The present study investigated the effect of blood volume (BV)-controlled UF on the incidence of HD treatments with IMEs. This prospective randomised crossover study included hypotension-prone patients, characterised by occurrence of IMEs in at least 33% of HD treatments during a 6-week screening phase. These patients underwent 2 treatment phases, each lasting 6 weeks, in randomised order. Each patient served as their own control, treated with standard HD in one phase and with BV-controlled UF in the other phase. Thirty-four patients from 9 HD centres were enrolled; 26 could be included in the analysis population. In comparison with standard HD, BV-controlled UF reduced the percentage of HD sess...
Nephrology news & issues, 2001
The quality of water used for dialysis is not subject to any mandatory regulations in most Europe... more The quality of water used for dialysis is not subject to any mandatory regulations in most European countries. A survey of haemodialysis facilities in 14 countries carried out by the European Dialysis and Transplant Nurses Association/European Renal Care Association (EDTNA/ERCA) showed that the majority of centres aimed to meet the requirements of the European Pharmacopoeia, but only 50% carried out tests to check compliance. The wide variation in policies for maintaining and monitoring the equipment and the distribution system indicates that guidelines for water treatment are urgently needed in Europe.