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F Lopot

Publications and source records attributed to F Lopot.

At least 19 recordsLinked to original sources
PubMed2006

[Resting energy expenditure during hemodialysis].

Very few studies have so far reported about resting energy expenditure (REE) in chronic renal failure and there is no information available on REE during hemodialysis (HD). Hypothetically, we can expect an increase in REE during HD procedure (due to the inflammatory response to extracorporeal blood circuit). However, such increase in REE could be modified by thermal balance of the procedure. In our study, REE was measured by indirect calorimetry (Deltatrac Datex) in a group of 13 HD patients (7 males and 6 females, mean age 59.8 +/- 13.5 years). In each patient, REE was assessed during two HD sessions: one isothermic and one thermoneutral. All other HD parameters were kept constant. The control group consisted of 14 healthy subjects (4 males and 10 females, mean age 41.3 +/- 20.5 years) with normal renal function. There was a significant difference in thermal balance between the two HD settings: -199 kJ/HD in isothermic and -4kJ/HD in thermoneutral HD sessions (p < 0.01). Measured REE values obtained in HD patients before HD session (7 316 +/- 919 kJ/day/1.73 m2) did not differ significantly from those of the healthy controls (7 264 +/- 1 016 kJ/day/1.73 m2). Similarly, there was no significant difference in calculated EE values (Harris-Benedict equation). In the 10th minute of the HD session, there was a slight, transitory decrease in REE (mean decrease by 3.2% during isothermic and by 2.8% during thermoneutral HD session, ns). In the 70th minute, REE returned to pre-dialysis values. After a light meal in the 110th minute REE increased by 8% during isothermic and by 6.3% during thermoneutral HD session. At the end of the HD session (i.e. in the 215th minute) REE again returned to pre-dialysis values. Intra-dialysis changes in REE were similar in both isothermic and thermoneutral HD sessions. The results of our study did not confirm the expected influence of HD procedure on REE in the two different thermal HD settings. We conclude that there is no significant difference between REE in HD patients and healthy controls and that REE values are not significantly influenced by hemodialysis procedure.

Calorimetry, Indirect↗
PubMed2003

Comparison of different techniques of hemodialysis vascular access flow evaluation.

Measurement of vascular access flow (QVA) has been suggested as a method of choice for vascular access quality (VAQ) monitoring. Besides traditional duplex Doppler, a number of bedside methods based mostly on the Krivitski principle of QVA evaluation from recirculation at reversed needles (RX), have been developed. This work compares ultrasonic dilution (UD), taken as a reference, HD01, Transonic Systems; duplex Doppler (DD); thermodilution (TD), BTM, Fresenius; optodilutional RX measurement (ORX), Critline III, R-mode, HemaMetrics; direct optodilutional QVA evaluation from jumpwise changes in ultrafiltration rate at both normal and reversed needles connection (OABF), Critline III, ABF-mode; and direct transcutaneous optodilutional QVA evaluation (TQA), Critline III TQA. Firstly, reproducibility of each method was assessed by duplicate measurement at unchanged conditions. This was followed by paired measurement with each method performed at controlled change in relevant measurement condition (two different extracorporeal blood flows in UD and TD, changed sensor position in TQA). Finally paired measurements by each method and the reference method performed at identical conditions were evaluated to assess accuracy of each method. The simple Krivitski formula QVA=QB(1-RX)/RX was used wherever manual QVA calculation was needed. Very high reproducibility was seen in UD, both for measurement at the same extra corporeal blood flow (QB) (correlation coefficient of duplicate measurement r=0.9702, n=58) and for measurement at two different QB (r=0.9735, n=24), justifying its current status of a reference method in QVA evaluation. Slightly lower reproducibility of TD measurement at the same QB (r=0.9197, n=40) and at two different QB (r=0.8508, n=168) can be easily overcome by duplicate measurement with averaging. High correlation of TD vs. UD (r=0.9543, n=54) makes TD a viable clinical alternative in QVA evaluation. Consistently different QVA obtained at two different QB should prompt closer investigation of anatomical conditions of the access. Use of the simple Krivitski formula in TD (which measures total recirculation, i.e. sum of access recirculation and cardiopulmonary recirculation) brings about underestimation of QVA, which progressively increases from QVA of about 600 mL/min up. Good correlation, although with significant scatter (r=0.8691, n=27) was found between the DD- and UD-based QVA. By far the worst reproducibility at the same QB from among the investigated methods was found in ORX (0.6430, n 23). Also the correlation of ORX vs. UD was lower than in other methods (r=0.702, n=33) and general overestimation of QVA by about 25% was noted. Correlation of OABF vs. UD (r=0.6957, n=26) was slightly better than that of ORX and it gave less overestimated values. The TQA method showed very high reproducibility (r=0.9712, n=85), however only for unchanged sensor position. Correlation of QVA measured at two different sensor positions was much worse (r=0.7255, n=22). Correspondence of TQA vs. UD was satisfactory (r=0.8077, n=36). Skilled and experienced operators are a must with this method.

Catheters, Indwelling↗
PubMed2002

Age-related extracellular to total body water volume ratio (Ecv/TBW)--can it be used for "dry weight" determination in dialysis patients? Application of multifrequency bioimpedance measurement.

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 extracellular origin of ultrafiltration as well as normalisation of the ECV/TBW ratio towards the end of dialysis. Supporting evidence of increasing ECV/TBW value with age was also found in literature. Although the suggested method needs detailed analysis of possible disturbing factors (ethnic "specificity" of the reference ECV/TBW vs. age characteristics in health, possible difference in "biological" and "physical" age of dialysis patient and others), the article is published at this early stage to enable wider testing of the proposed novel method by different investigators.

Adolescent↗
PubMed2001

[Evaluation of vascular access for hemodialysis using combined measurement of recirculation in normal and inverted needle placement and determination of blood flow through the access].

The article describes novel method of vascular access quality assessment by means of combined measurement of recirculation with normal and inverse needles placement and calculation of vascular access blood flow from the recirculation data. Blood flow values seen in a large group of patients ranged from as low as 200 ml/min up to as high as 2 l/min. Females and diabetics exhibited lower values as compared to males and non-diabetics. The method enables to detect a number of anomalous sates which cannot be detected by conventional means based on monitoring of pressures or recirculation measurement at normal needles placement only (stenosis between both needles, uintentionally erroneous placement of needles in accesses with a loop). Assessment of access blood flow is suitable also for evaluation of interventions on the access, such as percutaneous transluminal angioplasty or surgical narrowing of anastomosis in case of too high blood flow.

Arteriovenous Shunt, Surgical↗
PubMed2001

Treating and monitoring water for dialysis in Europe.

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.

Disinfection↗
PubMed1998

[The method of calculating the numeric value of the KT/V index in the evaluation of effectiveness of peritoneal dialysis].

BACKGROUND: 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. METHODS AND RESULTS: 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. CONCLUSIONS: The BP/V index must be assessed always by the same method with maximum accuracy. When presenting results or comparing results of different departments, the method of calculation must be stated.

Adult↗
PubMed1997

Computational analysis of blood volume dynamics during hemodialysis.

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 cumulative 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, compliance of his cardiovascular system is dominant. BV is also more reduced in patients with lower values of total plasma protein content and/or lower hematocrit. The BV reduction dynamic component is primarily influenced by the applied ultrafiltration rate. A certain influence is also exerted by the ultrafiltration coefficient of the capillary wall which may vary in different individuals.

Blood Proteins↗
PubMed1996

Multifrequency bioimpedance in assessment of dry weight in haemodialysis.

The use of multifrequency bioimpedance (MFB) for determination of dry weight (DW) in haemodialysis (HD) patients was evaluated in three studies. In Study 1, the fluid state [total body water (TBW) and extracellular volume (ECV)] was measured by MFB in 82 normotensive patients. 41 hypertensive patients and in 30 healthy subjects. TBW and ECV were expressed as per cent of body weight (BW). In Study 2, DW of five hypertensive HD patients was gradually decreased during 3 months and ECV (MFB) and blood pressure (48 h ambulatory blood pressure monitoring) were measured at the beginning and end of study. In Study 3, we measured the fluid status repeatedly by MFB and the diameter of the inferior vena cava (DIVC) by ultrasound before, during and 2 h post-HD. In Study 1, the hypertensive patients had significantly greater TBW (P < 0.05) than the normotensive patients before (50.3 +/- 6.5% vs 47.6 +/- 5.8%) and after HD (48.8 +/- 7.8% vs 45.7 +/- 6.4%) and ECV (P < 0.001) before (29.4 +/- 3.6% vs 26.8 +/- 3.5%) and after HD (27.0 +/- 4.0% vs 24.6 +/- 3.5%), Post-HD ECV in the normotensive patients was similar to that in the healthy subjects. In Study 2, more efficient ultrafiltration resulted in reduction of BW and ECV along with a decrease in blood pressure and need for antihypertensive medication. In Study 3, both ECV and DIVC decreased following the removal of fluid during HD. ECV maintained stable values during the post-HD period, unlike DIVC which increased significantly (P < 0.005) due to refilling from the interstitial space. We conclude that MFB is an appropriate non-invasive method for DW determination, which is highly reproducible and technically simple to use.

Adult↗
PubMed1996

Use of continuous blood volume monitoring to detect inadequately high dry weight.

A continuous blood volume monitoring (CBVM) device (Inline Diagnostics, Riverdale, USA) was used to study response to prescribed ultrafiltration during haemodialysis (HD) in 66 stabilised HD patients. Fifty percent of patients showed the expected linear decrease in BV right from the beginning of HD (group 1), 32% exhibited no decrease at all (group 2), while eighteen percent formed the transient group 3 which showed a plateau of varying length after which a decrease occurred. The correct setting of dry weight was verified through evaluation of the ratio of extracellular fluid volume to total body water (VEC/TBW) in 26 patients by means of whole body multifrequency impedometry MFI (Xitron Tech., San Diego, USA) and through measurement of the Vena Cava Inferior diameter (VCID) pre and post HD (in 6 and 5 patients from groups 1 and 3 and from group 2, respectively). The mean VEC/TBW in groups 1 and 3 was 0.56 pre and 0.51 post HD as compared to 0.583 and 0.551 in group 2. VCID decreased on average by 14.1% in groups 1 and 3 but remained stable in group 2. Both findings thus confirmed inadequately high estimation of dry weight. Since CBVM is extremely easy to perform it can be used as a method of choice in detecting inadequately high prescribed dry weight. The status of the cardiovascular system must always be considered before final judgement is made.

Blood Volume↗
PubMed1995

[Measurement of water content and distribution using whole-body multifrequency impedance in a healthy population in diseases of the kidney].

BACKGROUND: The whole-body multifrequency impedometry (MFI) is a new noninvasive method suggested for assessment of hydration status and distribution of the total body water into extra- and intracellular compartment. However, due to its as yet limited use reference values are still lacking. The aim of this work was to evaluate total body water (TBW) and its intra- (VIC) and extracellular compartment (VEC) from electrical resistances of intra- and extracellular fluid and to measure cell membrane capacity by means of MFI in healthy population and in renal patients. METHODS AND RESULTS: MFI investigation was performed in 21 healthy individuals (group A), 19 patients followed for renal insufficiency but not yet dialysed (group B) and in 15 haemodialysis patients (group C). The bioimpedance analyzer BIS 4000B (Xitron Technologies, San Diego, USA) was used throughout the study. TBW values established by means of MFI corresponded very closely to those ones calculated from Watson's formulae. The ratio VEC/TBW was found to be related to age with regression analysis parameters being very similar both in group A and groups B, C: group A: VEC/TBW = 0.4696 + 0.0011. Age (r = 0.512) groups B, C: VEC/TBW = 0.4574 + 0.0016. Age (r = 0.420). (For group C the post-dialysis values were used). Close correlation of VEC changes with ultrafiltered volume during haemodialysis session (r = 0.87 pri n = 87) indicates mostly extracellular origin of ultrafiltrate. The highest capacity of the cellular wall was found in healthy individuals, the lowest values were seen in the dialysed group. During dialysis the capacity rose to values seen in the non-dialysed group of renal patients. Interindividual scater over 40% in CIC value is caused by differences in body size. Normalized capacity CIC/VIC in healthy group is 0.104 nF/L +/- 10% on average. In renal patients values from 0.73 to 0.9 nF/L were seen. With regard to low variation of CIC/VIC in health, this parameter can be considered a possible candidate for screening assessment of the renal patients' hydration status. CONCLUSIONS: MFI was found suitable for monitoring of water content and distribution in the body both in out-patient department as well as during haemodialysis.

Adult↗
PubMed1995

Influence of the dialyzer membrane material on sodium transport in hemodialysis.

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 1: CC = 1.119 - 0.00175 x TPP; Hemophan 2: CC = 1.095 - 0.00111 x TPP; PMMA: CC = 1.0353 - 0.00044 x TPP; SCE:CC = 1.114 - 0.00145 x TPP; and Cuprophan 1:CC = 1.0562 - 0.00065 x TPP. The observed differences are attributed to the different charge densities of the membrane materials and suggest that for a precise description of sodium transport, the role of the membrane material needs to be considered.

Blood Proteins↗
PubMed1995

Study on sodium and potassium balance during hemodialysis.

To acquire data for adequate ultrafiltration (UF) control, sodium and potassium balance was investigated during hemodialysis (HD) in 16 hemodialyzed patients. Overall balances were evaluated from concentration measurements of the in- and outflowing dialysate and pre- and postdialysis plasma. The diffusive and convective part of the electrolyte removal and its intra- and extracellular space (ICS, ECS) component were calculated. During a 5-h HD, 40-110 mmol of potassium is removed, predominantly by diffusion (72-88%). Calculation shows that 40-70% of the removed amount is taken from the ICS. Sodium's overall HD showed much higher scatter, ranging from positive values to 500 mmol removal. The diffusive component was positive in most cases. By ultrafiltration sodium is removed in all cases. Calculations also showed in all cases that sodium was delivered to the ICS. This is in contradiction with the general belief that exchangeable sodium is distributed solely in ECS (1,2,6,7). This may be a sign of the effort to keep changes of ICS osmotic load at a minimum. Based on the finding of the exchange of sodium for potassium in the cellular wall, a method has been devised to calculate the UF fraction removed from EC (UFEC) expressed as a coefficient KEC = UFEC/UFToT, with UFToT being the total fluid volume removed during the HD session.

Humans↗
PubMed1995

Analysis of the urea generation rate and the protein catabolic rate in hemodialyzed patients.

The urea generation rate (G) and the protein catabolic rate (PCR) have been investigated in two groups of hemodialyzed patients over a whole week cycle, one with zero residual renal function (Kr = 0) dialyzed thrice weekly and the other dialyzed twice weekly with nonzero residual renal function. The two-pool model of urea kinetics was used. No relationship between patients' age and the PCR was found, and also no difference in the PCR between males and females was seen. All patients with a PCR < 0.8 g/kg/day had a midweek predialysis plasma urea level well below 25 mmol/L, which clearly documents the value of a kinetic approach in early detection of patients at risk for malnutrition. In the thrice weekly dialyzed group, a statistically significant relationship was found between PCR and KT/V:PCR = 0.582 + 0.253 x KT/V, r = 0.374 with p < 0.05. In the twice weekly dialyzed group with nonzero Kr, contribution of the residual renal function had to be included into KT/V to reach a level of statistical significance of PCR = 0.697 + 0.18 x KT/V, r = 0.481 with p < 0.05. With regard to values of Kr encountered in the investigated group (0-3.5 ml/min), its influence upon PCR is higher than a volumetrically equal increase in excretorial efficacy of the artificial kidney. The G in the thrice weekly dialyzed group was found to be dependent on the length of the interdialytic interval over which it was evaluated. Over the intervals Friday-Monday, Monday-Wednesday, and Wednesday-Friday the following mean values of G were obtained: 0.155, 0.180, and 0.188 mmol/min, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclic AMP Receptor Protein↗
PubMed1995

[Determination of dry weight of hemodialyzed patients on the basis of the ratio of extracellular fluid volume to total body fluid volume as measured by multifrequency impedance].

Whole body impedometry is relatively new non-invasive method to measure the distribution of total body water (TBW) between extra- and intracellular compartment (VEC, VIC). Having applied linear regression analysis onto the relation of the ratio of the extracellular volume to the volume of total body water (VEC/TBW) and the age in a group of healthy individuals very narrow scatter from the regression line was found. This line can thus be used as an indicator of normohydration status with respect to age. Assuming that the relation of VEC/TBW vs. age is the same in dialysed patients and that the state of normohydration corresponds to the so called dry weight, the VEC/TBW value can be used as a novel indicator of dry weight. Any deviation of the pre-dialysis VEC/TBW value from normal could easily be used to establish the desired ultrafiltration and dry weight. With regard to the known inaccuracy with which the dry weight is determined from purely clinical assessment this approach may lead to substantial objectivisation in determination of this principal parameter. It may be especially helpful in case of newly admitted patients. The suggested new approach to dry weight determination is supported by the finding of statistically significant relation between post-dialysis deviation of the VEC/TBW ratio from the normal value vs. blood volume reduction at the end of the dialysis session. Patients classified at the end of a dialysis session as still overhydrated by their VEC/TBW deviation from normal showed little or no reduction in their blood volume. An investigation of the Vena Cava Inferior diameter in a subgroup of these patients confirmed this finding showing no decrease at the end of dialysis. On the contrary, the patients whose post-dialysis VEC/TBW value was normal or below normal showed both significant reduction in their blood volume as well as decrease in the Vena Cava Inferior diameter.

Adult↗
PubMed1993

[Prediction of needs in dialysis therapy].

Planning of future needs of Renal Replacement Therapy (RRT) Programme is frequently based on comparison of national data with data from other countries. Often, the dynamics of RRT development is disregarded and dialysis and transplantation assessed as separate entities, too. Such approach may lead to underestimation of present level of RRT availability and overestimation of immediate future needs. Transplantation activity and number of patients requiring dialysis are interrelated variables. Under steady state, their relation may be described as N = TX + U where N denotes incidence of chronic renal failure, TX transplantation activity, and U stands for mortality rate of dialysed population. Considering mortality rate equal to 10% of dialysed population (P), an equation describing the interrelation of transplantation activity and number of patients requiring dialysis may be devised: P = (N - TX)/0.1. This equation can be used to calculate target values of RRT programme. The time course of RRT needs to reach the target figures may be predicted from a simple differential equation dP/dT = N - 0.1. P - TX, taking into account dynamic character of this process.

Czech Republic↗
PubMed1993

Clinical study of high-flux cuprammonium rayon hemodialysis membranes.

The aim of this crossover clinical study was to gain basic information on the hemocompatibility and effectiveness of recently developed high-flux membranes made of cuprammonium rayon with ultrafiltration coefficients of 10, 17, and 19 ml/mm Hg/h (S12W, SU12W, and SS12W dialyzers, respectively), and to identify any possible differences from a conventional membrane made of the same material with an ultrafiltration coefficient of 6 ml/mm Hg/h (C12W dialyzer). All the tested membranes led to an abrupt drop in leukocyte count in the initial phase of hemodialysis. In high-flux membranes, C5a anaphylatoxin would pass into the dialysate, but mean C5a anaphylatoxin concentrations in the dialysate were lower by orders of magnitude than its plasma concentrations, which behaved, in high- and low-flux membranes alike, typically of those made of nonsubstituted cellulose with no intermembrane differences. As judged by the concentrations of the thrombin-antithrombin III complex, the coagulation system was activated--again, without differences between membranes. The reduction rates for urea, creatinine, and phosphates were comparable for all the tested membranes. Compared with baseline, the post-dialysis serum concentrations of beta 2-microglobulin in high-flux membranes, unlike the low-flux membrane, were significantly lower. We conclude that there are no significant differences between the tested high- and low-flux membranes made of cuprammonium rayon in the monitored hemocompatibility parameters, and that high-flux membranes are capable of reducing serum beta 2-microglobulin concentrations.

Adult↗
PubMed1992

An equation for calculating postdialysis plasma sodium.

Well defined dry weight is a must for adequate UF control during haemodialysis (HD). However, interdialytic weight gain (delta BW) must not be excessive. delta BW is closely related to interdialytic thirst which in turn is strongly influenced by post-dialysis plasma sodium (CPNa post), but little is known about the desired CPNa post. The points below serve as a basis for establishing this value. a) Thirst is mediated by osmoreceptors. b) A strong correlation has been found between delta BW and intradialytic increase in plasma sodium but no such correlation exists with the interdialytic increase in plasma urea. This indicates that fluid intake between dialyses depends solely on electrolytes. c) Pre-dialysis plasma sodium in an individual is stable, indicating that the patient is at his "set value" of electrolyte osmolality. d) Half of the potassium removed during HD comes from the extra- and half from the intracellular space. Assuming that it is desirable not to disturb a patient's pre-dialysis osmotic steady state, it can be calculated that the desired CPNa post should be higher than the pre-dialysis value by half of the intradialytic plasma potassium drop, i.e., approx. CPNa post = CPNa pre + 1 to 2 mmol/l.

Humans↗