| 1. |
- Adoberg, Annika, et al.
(författare)
-
Treatment with Paracetamol Can Interfere with the Intradialytic Optical Estimation in Spent Dialysate of Uric Acid but Not of Indoxyl Sulfate
- 2022
-
Ingår i: Toxins. - : MDPI. - 2072-6651. ; 14:9
-
Tidskriftsartikel (refereegranskat)abstract
- Optical online methods are used to monitor the haemodialysis treatment efficiency of end stage kidney disease (ESKD) patients. The aim of this study was to analyse the effect of the administration of UV-absorbing drugs, such as paracetamol (Par), on the accuracy of optical monitoring the removal of uremic toxins uric acid (UA) and indoxyl sulfate (IS) during standard haemodialysis (HD) and haemodiafiltration (HDF) treatments. Nine patients received Par in daily dosages 1-4 g for 30 sessions. For 137 sessions, in 36 patients the total daily dosage of UV-absorbing drugs was less than 500 mg, and for 6 sessions 3 patients received additional UV-absorbing drugs. Par administration slightly affected the accuracy of optically assessed removal of UA expressed as bias between optically and laboratory-assessed reduction ratios (RR) during HD but not HDF employing UV absorbance of spent dialysate (p < 0.05) at 295 nm wavelength with the strongest correlation between the concentration of UA and absorbance. Corresponding removal of IS based on fluorescence at Ex280/Em400 nm during HD and HDF was not affected. Administration of UV-absorbing drugs may in some settings influence the accuracy of optical assessments in spent dialysate of the removal of uremic solutes during haemodialysis treatment of ESKD patients.
|
|
| 2. |
- Andersson, Roger, et al.
(författare)
-
Analysis of the relationship between UV-absorbance of solute contents during a dialysis session
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, the influence from patient anamnesis and haemodialysis session specifications onto the relationship between obtained ultra violet (UV) absorbance and urea concentration in the spent dialysate were discussed. A characterisation of the relationship was done by an intercept value and a slope. Recently, a new a dialysate monitoring device, using UV- absorbance, been developed by our group which has found a relationship between the UV- absorbance and waste products in the dialysate but this relationship vary between patients. In the present investigation, 13 patients performing totally 84 sessions were characterised using 31 possible affecting parameters. Using a multi-regression analysis 11 parameters were found significant as affecting parameters. In a novel mathematical model approach the obtained UV- absorbance and incorporating possible affecting parameters we could predict urea concentration from the UV-absorption in the spent dialysate in the total material of patients and dialysis sessions. For all the 84 sessions R2 between 0.938 and 0.996 were obtained. A performed analysis of variance rejects the assumption of equal conditions for the relationship between diabetics and non-diabetics patients in the material (F=5.2 for intercept and F=14.4 for slope). The urea concentration could be estimated with an accuracy of 11% (one standard deviation) which is normally clinically sufficient. The non-invasive UV -absorption method therefore seems to have great potential for monitoring and control haemodialysis sessions.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Arund, Jürgen, et al.
(författare)
-
Do Only Small Uremic Toxins, Chromophores, Contribute to the Online Dialysis Dose Monitoring by UV Absorbance?
- 2012
-
Ingår i: Toxins. - : MDPI AG. - 2072-6651. ; 4:10, s. 849-861
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to evaluate the contributions of the main chromophores to the total UV absorbance of the spent dialysate and to assess removal dynamics of these solutes during optical on-line dialysis dose monitoring. High performance chromatography was used to separate and quantify UV-absorbing solutes in the spent dialysate sampled at the start and at the end of dialysis sessions. Chromatograms were monitored at 210, 254 and 280 nm routinely and full absorption spectra were registered between 200 and 400 nm. Nearly 95% of UV absorbance originates from solutes with high removal ratio, such as uric acid. The contributions of different solute groups vary at different wavelengths and there are dynamical changes in contributions during the single dialysis session. However, large standard deviation of the average contribution values within a series of sessions indicates remarkable differences between individual treatments. A noteworthy contribution of Paracetamol and its metabolites to the total UV absorbance was determined at all three wavelengths. Contribution of slowly dialyzed uremic solutes, such as indoxyl sulfate, was negligible.
|
|
| 7. |
- Arund, Jurgen, et al.
(författare)
-
Is Fluorescence Valid to Monitor Removal of Protein Bound Uremic Solutes in Dialysis?
- 2016
-
Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 11:5
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate the contribution and removal dynamics of the main fluorophores during dialysis by analyzing the spent dialysate samples to prove the hypothesis whether the fluorescence of spent dialysate can be utilized for monitoring removal of any of the protein bound uremic solute. A high performance liquid chromatography system was used to separate and quantify fluorophoric solutes in the spent dialysate sampled at the start and the end of 99 dialysis sessions, including 57 hemodialysis and 42 hemodiafiltration treatments. Fluorescence was acquired at excitation 280 nm and emission 360 nm. The main fluorophores found in samples were identified as indole derivatives: tryptophan, indoxyl glucuronide, indoxyl sulfate, 5-hydroxy-indoleacetic acid, indoleacetyl glutamine, and indoleacetic acid. The highest contribution (35 +/- 11%) was found to arise from indoxyl sulfate. Strong correlation between contribution values at the start and end of dialysis (R-2 = 0.90) indicated to the stable contribution during the course of the dialysis. The reduction ratio of indoxyl sulfate was very close to the decrease of the total fluorescence signal of the spent dialysate (49 +/- 14% vs 51 +/- 13% respectively, P = 0.30, N = 99) and there was strong correlation between these reduction ratio values (R-2 = 0.86). On-line fluorescence measurements were carried out to illustrate the technological possibility for real-time dialysis fluorescence monitoring reflecting the removal of the main fluorophores from blood into spent dialysate. In summary, since a predominant part of the fluorescence signal at excitation 280 nm and emission 360 nm in the spent dialysate originates from protein bound derivatives of indoles, metabolites of tryptophan and indole, the fluorescence signal at this wavelength region has high potential to be utilized for monitoring the removal of slowly dialyzed uremic toxin indoxyl sulfate.
|
|
| 8. |
|
|
| 9. |
- Enberg, Per, et al.
(författare)
-
Utilization of UV absorbance for estimation of phosphate elimination during hemodiafiltration
- 2012
-
Ingår i: Nephron. Clinical practice. - : S. Karger. - 1660-8151 .- 2235-3186 .- 1660-2110. ; 121:1-2, s. c1-c9
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Phosphate is an important factor in explaining the high progress of vascular calcification among dialysis patients. Today, phosphate concentration is measured in plasma on a regular basis. The aim of this study was to find out if it is possible to estimate total removed phosphate (TRp) in spent dialysate utilizing UV absorbance during hemodiafiltration. Methods: Eleven patients were monitored online with UV absorbance at 297 nm, three times during one week each (n = 33). Dialysate samples were taken at different times during treatment and from a collection tank to chemically determine phosphate concentrations. Two mathematical models (UVIND and UVGROUP) were tested to estimate TRp with supervision by UV absorbance and compared with TRp measured in the tank (reference). Results: High correlation between UV absorbance and phosphate concentration for each single patient and lower for the whole group together was found. TRp was (mean +/- SD) 30.7 +/- 7.3 mmol for the reference and 30.8 +/- 8.2 and 29.1 +/- 5.2 mmol for UVIND and UVGROUP, respectively (p > 0.05). Conclusion: This study demonstrates a novel possibility to estimate TRp based on linear relationship between online monitoring of UV absorbance and concentration of phosphate in spent dialysate.
|
|
| 10. |
- Fridolin, Ivo, et al.
(författare)
-
A New Optical Method for Measuring Creatinine Concentration Removed During Dialysis
- 2010
-
Ingår i: XII Mediterranean Conference on Medical and Biological Engineering and Computing 2010 IFMBE Proceedings, 2010. - Berlin, Heidelberg : Springer. - 9783642130380 - 9783642130397 ; , s. 379-382
-
Konferensbidrag (refereegranskat)abstract
- The aim of this study was to compare creatinine (Cr) concentration measurements removed during dialysis by two optical algorithms based on single wavelength and multiwavelength UV-absorbance. Ten uremic patients, three females and seven males, mean age 62.6 ± 18.6 years, on chronic thrice-weekly hemodialysis were included in the study. Double-beam spectrophotometer (Shimatsu UV-2401 PC, Japan) was used for the determination of UV-absorbance in the collected spent dialysate samples. Two optical algorithms were developed to calculate Cr concentration removed during dialysis from measured UVabsorbance: (i) an algorithm utilizing only a single wavelength, revealing Cr concentration Cr_sw; (ii) an algorithm utilizing several wavelengths (multiwavelength algorithm), revealing Cr concentration Cr_mw. The mean value of Cr estimated at the laboratory was 107 ± 46,7 micromol/l, while UV-absorbance as Cr_sw (242 nm) was 107 ± 42.7 micromol/l, and 107 ± 44.7 micromol/l as Cr_mw. The mean concentrations were not significantly different (P = 0.99). The systematic errors, using Cr_lab as a reference, were -2.7% for Cr_sw and -1.7% for Cr_mw, and random errors were 17.3% and 13.6% for Cr_sw and Cr_mw, respectively. The systematic error was not significantly different for two optical algorithms (P = 0.25). The random error decreased significantly (P < 0.05) using Cr_mw algorithm compared to the Cr_sw model. In summary, the creatinine concentration removed during dialysis can be estimated with UV-absorbance technique.
|
|
| 11. |
|
|
| 12. |
- Fridolin, Ivo, et al.
(författare)
-
Measurement of solutes in dialysate using UV absorption
- 2001
-
Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 4263, s. 40-47
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this work was to describe a new method for optical monitoring of solutes in a spent dialysate. The method utilizes UV light absorption employing a commercially available spectrophotometer. Measurements were performed both on collected dialysate samples and on-line. The concentration of several removed solutes and electrolytes in the serum and in the dialysate was determined simultaneously using standard laboratory techniques. During on-line monitoring the spectrophotometer was connected to the fluid outlet of the dialysis machine. On-line measurements during a single hemodialysis session demonstrated a possibility to monitor deviations in the dialysator performance (e.g. dialysator in bypass). The experimental results indicated a good correlation between UV absorption and several removed solutes (urea, creatinine) in the spent dialysate. The correlation coefficient for urea and creatinine concentrations in the dialysate was very high for every individual treatment. The UV absorbance correlates well to the concentrations of several solutes thought to be uremic toxins. The results indicate that the technique can be used as a continuous, on-line method for monitoring deviations in the dialysator performance and may estimate the removal of the overall toxins. In the future, the new method will be used to evaluate parameters describing delivery of the prescribed treatment dose such as KT/V and Urea Reduction Rate (URR).
|
|
| 13. |
- Fridolin, Ivo, et al.
(författare)
-
On-line monitoring of solutes in dialysate using adsorption of ultraviolet radiation : technical description
- 2002
-
Ingår i: International Journal of Artificial Organs. - 0391-3988 .- 1724-6040. ; 25:8, s. 748-761
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE:The aim of this work was to describe a new optical method for monitoring solutes in a spent dialysate using absorption of UV radiation.METHOD:The method utilises UV-absorbance determined in the spent dialysate using a spectrophotometrical set-up. Measurements were performed both on collected dialysate samples and on-line. During on-line monitoring, a spectrophotometer was connected to the fluid outlet of the dialysis machine, with all spent dialysate passing through a specially-designed cuvette for optical single-wavelength measurements. The concentrations of several substances of various molecular sizes, electrical charge, transport mechanism, etc. were determined in the dialysate and in the blood using standard laboratory techniques. The correlation coefficient between UV-absorbance of the spent dialysate and concentration of the substances in the spent dialysate and in the blood was calculated from data based on the collected samples.RESULTS:The obtained on-line UV-absorbance curve demonstrates the possibility to follow a single hemodialysis session continuously and to monitor deviations in the dialysator performance using UV-absorbance. The experimental results indicate a very good correlation between UV-absorbance and several small waste solutes removed such as urea, creatinine and uric acid in the spent dialysate and in the blood for every individual treatment at a fixed wavelength of 285 nm. Moreover, a good correlation between the UV-absorbance and substances like potassium, phosphate and beta2-microglobulin was obtained. The lowest correlation was achieved for sodium, calcium, glucose, vitamin B12 and albumin.CONCLUSIONS:A technique for on-line monitoring of solutes in the spent dialysate utilising the UV-absorbance was developed. On-line monitoring during a single hemodialysis session exploiting UV-absorbance represents a possibility to follow a single hemodialysis session continuously and monitor deviations in dialysis efficiency (e.g. changes in blood flow and clearance). The UV-absorbance correlates well to the concentration of several solutes known to accumulate in dialysis patients indicating that the technique can be used to estimate the removal of retained substances.
|
|
| 14. |
- Fridolin, Ivo, 1971-, et al.
(författare)
-
On-line monitoring of solutes in dialysate using wavelength-dependent absorption of ultraviolet radiation
- 2003
-
Ingår i: Medical and Biological Engineering and Computing. - 0140-0118 .- 1741-0444. ; 41:3, s. 263-270
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to assess the wavelength dependence of the UV absorbance during monitoring of different compounds in the dialysate. UV absorbance was determined by using a double-beam spectrophotometer on dialysate samples taken at pre-determined times during dialysis, over a wavelength range of 180–380 nm. Concentrations of several removed substances, such as urea, creatinine, uric acid, phosphate and β 2-microglobulin, were determined in the blood and in the spent dialysate samples using standard laboratory techniques. Millimolar extinction coefficients, for urea, creatinine, monosodium phosphate and uric acid were determined during laboratory bench experiments. The correlation between UV absorbance and substances both in the dialysate and in the blood was calculated at all wavelengths. A time-dependent UV absorbance was determined on the collected dialysate samples from a single dialysis session over a wavelength range of 200–330 nm. The highest contribution from observed compounds relative to the mean value of the absorbance was found around 300 nm and was approximately 70%. The main contribution to the total absorbance from uric acid was confirmed at this wavelength. The highest correlation for uric acid, creatinine and urea was obtained at wavelengths from 280 nm to 320 nm, both in the spent dialysate and in the blood. The wavelength region with the highest correlation for phosphate and β 2-microglobulin, with a suitable UV-absorbance dynamic range, was from 300 to 330 nm. In the wavelength range of 220–270 nm the highest absorbance sensitivity for the observed substances was obtained. A suitable wavelength range for instrumental design seems tobe around 290–330 nm. The relatively high correlation between UV absorbance and the substances in the spent dialysate and in the blood indicates that the UV-absorbance technique can estimate the removal of several retained solutes known to accumulate in dialysis patients.
|
|
| 15. |
|
|
| 16. |
- Fridolin, Ivo, et al.
(författare)
-
Optical non-invasive technique for vessel imaging : I. Experimental results
- 2000
-
Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 45:12, s. 3765-3778
-
Tidskriftsartikel (refereegranskat)abstract
- This paper investigates some prerequisites for vessel imaging based on diffuse reflectance measurements in order to develop an optical non-invasive method for the imaging and monitoring of vessels.The method utilizes near-infrared (NIR) radiation (890 nm) from a light emitting diode. The light is guided into the tissue via an optical fibre (diameter 1.0 mm). The backscattered light is collected by an optical fibre of the same type and detected by an optical power meter. The fibres are moved over the skin in two directions with the aid of two motors operated by a microcomputer. Spatially resolved reflectance at the skin surface could be presented as a vessel-map in a colour-coded form on a computer screen.Experimental results indicate that the vessel imaging facility depends upon source-detector separation, relative position and vessel depth, and does not depend essentially on the radiant power from the light source. It is shown that, by a proper choice of probe parameters, one can improve the vessel identification ability.After vessel imaging the technique can potentially be used to monitor several physiological parameters on a selected vascular bed or to distinguish between injured and healthy tissue by monitoring local blood flow, oxygen saturation and the recirculation, pre- and post-operatively.
|
|
| 17. |
- Fridolin, Ivo, 1971-, et al.
(författare)
-
Optical non-invasive technique for vessel imaging : II. A simplified photon diffusion analysis
- 2000
-
Ingår i: Physics in Medicine and Biology. - : Institute of Physics (IOP). - 0031-9155 .- 1361-6560. ; 45:12, s. 3779-3792
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this paper is to explain theoretically the origin of previously presented experimental results by an optical non-invasive method using NIR for imaging blood vessels based on a specific combination of several physical parameters. The theoretical model is based on the diffusion approximation derived from the transport theory deep in a bulk tissue. An analytical solution was obtained describing photon behaviour under certain conditions during vessel identification. The modelled results indicate that the vessel identification facility depends upon source-detector separation and vessel depth, and does not depend essentially on the radiant power from the light source. The solution offers a relatively simple theoretical explanation of the experimental results and can be applied to several other clinical applications using similar technical solutions.
|
|
| 18. |
- Fridolin, Ivo, 1971-
(författare)
-
Photon propagation in tissue and in biological fluids : applied for vascular imaging and haemodialysis monitoring
- 2003
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis focuses on the photon propagation in tissue and in biological fluids in two main areas: (1) optical vessel imaging and (2) monitoring solutes removed in haemodialysis.The aim of the optical vessel imaging study was to design and assess a new optical scanning technique for vessel imaging using NIR radiation. The results indicated that veins could be determined at three vascular levels (superficial, intermediate and deep) down to 3 mm. Moreover, experimental results demonstrated that the vessel imaging facility depends upon source-detector separation, relative position, and vessel depth and does not depend essentially on the radiant power from the light source. After vessel imaging the technique can potentially be used to monitor several physiological parameters on a selected vascular bed (e.g. local blood flow, oxygen saturation).The theoretical model, based on the diffusion approximation, was developed to explain theoretically the origin of experimental results. An analytical solution was obtained describing photon propagation under certain conditions during vessel identification. The modelled results confirmed previously obtained experimental results.A new optical method for monitoring solutes in a spent dialysate using absorption of UV-radiation was developed. The obtained on-line UV-absorbance curve demonstrates the possibility to follow a single haemodialysis session continuously and to monitor deviations in the dialysator performance using UV-absorbance. The experimental results indicated that the UV-absorbance correlates well to the concentration of several solutes known to accumulate in dialysis patients indicating that the technique can be used to estimate the removal of retained substances.Furthermore, a clinical study suggested that the delivered dialysis dose in terms of the traditional urea Kt/V could be estimated by on-line measurement of the UV-absorption in the spent dialysate. This means that the UV-method may add a new methodology for improvement of the quality and adequacy of the dialysis.An investigation of the wavelength dependence of the UV-absorbance when monitoring different compounds in the dialysate showed that the UV-absorbance correlates well to several small molecular weight solutes ( < 200 D), around 290-310 nm. The highest contribution to the total absorbance from the observed compounds was confirmed in this wavelength region. The results indicated, that it might be possible to measure the elimination of several substances that are retained in the uraemic patients and with potential clinical significance. From thisviewpoint, the UV-absorbance monitoring technique may become a more universal method to ensure the quality and adequacy of the dialysis.
|
|
| 19. |
|
|
| 20. |
- Holmar, Jana, et al.
(författare)
-
An Optical Method for Serum Calcium and Phosphorus Level Assessment during Hemodialysis
- 2015
-
Ingår i: Toxins. - BASEL, SWITZERLAND : MDPI AG. - 2072-6651. ; 7:3, s. 719-727
-
Tidskriftsartikel (refereegranskat)abstract
- Survival among hemodialysis patients is disturbingly low, partly because vascular calcification (VC) and cardiovascular disease are highly prevalent. Elevated serum phosphorus (P) and calcium (Ca) levels play an essential role in the formation of VC events. The purpose of the current study was to reveal optical monitoring possibilities of serum P and Ca values during dialysis. Twenty-eight patients from Tallinn (Estonia) and Linköping (Sweden) were included in the study. The serum levels of Ca and P on the basis of optical information, i.e., absorbance and fluorescence of the spent dialysate (optical method) were assessed. Obtained levels were compared in means and SD. The mean serum level of Ca was 2.54 ± 0.21 and 2.53 ± 0.19 mmol/L; P levels varied between 1.08 ± 0.51 and 1.08 ± 0.48 mmol/L, measured in the laboratory and estimated by the optical method respectively. The levels achieved were not significantly different (p = 0.5). The Bland-Altman 95% limits of agreement between the two methods varied from -0.19 to 0.19 for Ca and from -0.37 to 0.37 in the case of P. In conclusion, optical monitoring of the spent dialysate for assessing the serum levels of Ca and P during dialysis seems to be feasible and could offer valuable and continuous information to medical staff.
|
|
| 21. |
- Holmar, Jana, et al.
(författare)
-
Estimation of dialysis patients survival through combined approach of small molecule uremic markers
- 2014
-
Ingår i: Proceedings of the Estonian Academy of Sciences. - : Estonian Academy Publishers. - 1736-6046 .- 1736-7530. ; 63:3, s. 227-233
-
Tidskriftsartikel (refereegranskat)abstract
- Survival rate of dialysis patients is still alarmingly low and various factors may have in it an important role. The purpose of this study was to observe the relationship between the survival of dialysis patients and the serum level of urea, creatinine, and uric acid (UA). Serum urea and creatinine concentrations may express patients nutritional status and muscle mass, and high UA value may refer to higher risk for cardiovascular events. The idea of combining the concentrations and removal of urea and UA into a single model for predicting the patients outcome is introduced. The study included 33 hemodialysis patients from Link ping, Sweden and 10 from Tallinn, Estonia. Kaplan-Meier analysis was used for survival analysis. Logistic and Cox regression analysis was applied to create models for predicting patients three-year survival. It was observed that higher serum UA is significantly related to poor survival in dialysis patients (p = 0.026). A reverse effect was observed in case of urea (p = 0.095). The level of creatinine was not related to survival (p = 0.905). The best logistic regression model for predicting patients outcome included both UA and urea based parameters (Chi Square 21.0, p = 0.0001). Survival of dialysis patients seems to be determined by a set of causal factors and combined models may have a predictive relevance. A possibility for automatic online monitoring of small molecule uremic markers is proposed. Since the number of participating patients was small, larger studies including more patients and testing the models in independent validation cohort is the future goal.
|
|
| 22. |
|
|
| 23. |
- Holmar, Jana, et al.
(författare)
-
Estimation of removed uremic toxin indoxyl sulphate during hemodialysis by using optical data of the spent dialysate
- 2013
-
Ingår i: IEEE Engineering in Medicine and Biology Society Conference Proceedings. - : IEEE. ; , s. 6707-6710
-
Konferensbidrag (refereegranskat)abstract
- The aim of this study was to explore the possibility to determine the amount of total removed Indoxyl Sulphate (TR_IS) during dialysis session, an optical method utilizing absorbance and fluorescence spectral data of the spent dialysate was used. Eight uremic patients from Linköping, Sweden and 10 from Tallinn, Estonia, were studied during dialysis treatments. Dialysate samples were taken during each treatment and analyzed at a laboratory. Fluorescence and absorbance spectra of the spent dialysate were measured with spectrofluorophotometer and spectrophotometer. The spectral values were transformed into IS concentration using multiple linear regression model from the total material noted as optical method (Opt). IS concentration was estimated using high-performance liquid chromatography (HPLC) method as a reference. TR_IS values were calculated. Achieved results were compared regarding mean values and SD and collated with the amount of total removed urea value (TR_Urea) for the same dialysis procedures. Mean TR value ± SD (mg) for urea was 28 947 ± 9 241; TR for IS was 151.4 ± 87.3 estimated by HPLC and 149.4 ± 84.9 estimated by Opt. The TR_IS values were not significantly different (p ≤ 0.05). This study indicates, that it is possible to estimate TR_IS using only spectral values of the spent dialysate and the parameter can be used for quantifying the elimination of protein bound uremic toxins during the dialysis procedure.
|
|
| 24. |
- Holmar, Jana, et al.
(författare)
-
New optical method for estimation of protein bound uremic toxins elimination
- 2012
-
Konferensbidrag (refereegranskat)abstract
- The aim of this study was to investigate the possibility to determine the amount of removed Indoxyl Sulphate (IS) during dialysis session. An optical method using fluorescence spectra was used.Eight uremic patients were studied during three dialysis treatments per patient in one week at the Department of Nephrology at Linköping University Hospital. Dialysate samples were taken during each treatment and analyzed at laboratory. IS concentration was estimated using HPLC method, and fluorescence spectra was measured with spectrofluorophotometer. The fluorescence spectral values were transformed into IS concentration using regression model from the total material noted as fluorescence method (F). Removal ratio (RR) was calculated for both. Achieved results were compared regarding mean values and SD and collated with urea reduction ratio (URR) of same dialysis procedures.Mean RR value (%) for urea was 74.55±8.11. RR for IS estimated by HPLC was 54.01±8.44 % and by F 58.95±10.94 %. The values were not significantly different (p≤0.05).This study indicates, that it is possible to estimate RR of IS using only fluorescence values of the spent dialysate and achieved parameter can be used for describing the elimination of protein bound uremic toxins during the dialysis procedure.
|
|
| 25. |
|
|
| 26. |
|
|
| 27. |
- Holmar, Jana, et al.
(författare)
-
Optical method for cardiovascular risk marker uric acid removal assessment during dialysis
- 2012
-
Ingår i: Scientific World Journal. - : Hindawi Limited. - 1537-744X. ; 2012, s. 8-
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to estimate the concentration of uric acid (UA) optically by using the original and processed ultraviolet (UV) absorbance spectra of spent dialysate. Also, the effect of using several wavelengths (multi-wavelength algorithms) for estimation was examined. This paper gives an overview of seven studies carried out in Linköping, Sweden, and Tallinn, Estonia. A total of 60 patients were monitored over their 188 dialysis treatment procedures. Dialysate samples were taken and analysed by means of UA concentration in a chemical laboratory and with a double-beam spectrophotometer. The measured UV absorbance spectra were processed. Three models for the original and three for the first derivate of UV absorbance were created; concentrations of UA from the different methods were finally compared in terms of mean values and SD. The mean concentration (micromol/L) of UA was 49.7 ± 23.0 measured in the chemical laboratory, and 48.9 ± 22.4 calculated with the best estimate among all models. The concentrations were not significantly different (P ≥ 0.17). It was found that using a multi-wavelength and processed signal approach leads to more accurate results, and therefore these approaches should be used in future.
|
|
| 28. |
- Holmar, Jana, et al.
(författare)
-
Quantification of indoxyl sulphate in the spent dialysate using fluorescence spectra
- 2011
-
Ingår i: IFMBE Proceedings. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1680-0737. ; 34, s. 45-48
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the possibility to determine the amount of Indoxyl Sulphate (IS) in the spent dialysate using fluorescence spectra. Eight uremic patients from Linköping were studied during their three dialysis treatments in one week at the Department of Dialysis and Nephrology at Linköping University Hospital. Dialysate samples were taken during each treatment and analyzed, IS concentration was estimated using HPLC method, and fluorescence spectra was measured with spectrofluorophotometer. The fluorescence spectral values were transformed into IS concentration using regression model from total material noted as fluorescence method (F). Achieved results were compared regarding mean values and SD. Mean value of IS estimated by HPLC was 1.21±0.77 mg/l and by F 1.22±0.72 mg/l. Concentrations were not significantly different (p≤0,05). This study indicates, that it is possible to estimate the concentration of IS using only fluorescence values of the spent dialysate.
|
|
| 29. |
|
|
| 30. |
|
|
| 31. |
- Jerotskaja, Jana, et al.
(författare)
-
A multicentre study of an enhanced optical method for measuring concentration of uric acid removed during dialysis.
- 2009
-
Ingår i: Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2009. EMBC 2009. - 9781424432967 ; , s. 1477-1480
-
Konferensbidrag (refereegranskat)abstract
- The aim of this study was to compare concentration measurements of uric acid (UA) removed during dialysis by two algorithms based on UV-absorbance and the 1st derivate of UV absorbance. Ten uremic patients from Tallinn and ten from Linköping, during 30+40 haemodialysis treatments, were followed at the Departments of Dialysis and Nephrology at North-Estonian Medical Centre and at Linköping University Hospital. The dialysate samples were taken and analyzed by means of UA concentration at the chemical laboratory and with a double-beam spectrophotometer. UV absorbance and derivate of UV absorbance was transformed into UA concentration in the spent dialysate using the regression models from the calibration set of material, noted as UV-absorbance (UV_A) and the 1st derivate of UV absorbance (UV_D) method. These models were tested on validation set of material and concentrations of UA from the two methods were compared regarding mean values and SD. Mean concentration of UA were 52.7 +/- 25.0 micromol/l measured at the chemical laboratory (UA_Lab), 54.9 +/- 23.8 micromol/l determined by UV_A and 52.9 +/- 23.0 micromol/l determined by UV_D. The results of mean concentrations were not significantly different (p >/= 0.54). The systematic errors were -7.8 % and -3.3% and random errors were 15.8 % and 10.4 % using UV_A and UV_D respectively. The systematic and random errors were significantly different (p < 0.05) indicating that the new algorithm enables more accurate UA estimation.
|
|
| 32. |
- Jerotskaja, Jana, et al.
(författare)
-
Concentration of uric acid removed during dialysis. Estimated by multi wavelength and processed ultra violet absorbance spectra
- 2010
-
Ingår i: Engineering in Medicine and Biology Society (EMBC), 2010 Annual International Conference of the IEEE, ISSN: 1557-170X. - : IEEE. - 9781424441235 ; , s. 5791-5794
-
Konferensbidrag (refereegranskat)abstract
- The aim of this study was to estimate the concentration of uric acid (UA) optically by using original and processed ultra violet (UV) absorbance spectra's of the spent dialysate. Also the effect of using several wavelengths for estimation was examined. Ten uremic patients from Tallinn and ten from Linkoping, during 30+40 hemodialysis treatments, were followed at the Departments of Dialysis and Nephrology at North-Estonian Medical Centre and at Linkoping University Hospital. The dialysate samples were taken and analyzed by means of UA concentration at the chemical laboratory and with a doublebeam spectrophotometer. From the calibration set of material three models for original and three for Is' derivate of UV absorbance were created. These models were tested on validation set of material and concentrations of UA from the different methods were compared regarding mean values and SD. It was found that the concentration of UA can be estimated by UV absorbance method whereby using processed UV absorbance spectra and absorbance values from several wavelengths gives better and more accurate results.
|
|
| 33. |
|
|
| 34. |
- Jerotskaja, Jana, et al.
(författare)
-
Improved optical method for measuring concentration of uric acid removed during dialysis
- 2010
-
Ingår i: XII Mediterranean Conference on Medical and Biological Engineering and Computing 2010 IFMBE Proceedings, 2010. - Berlin, Heidelberg : Springer. ; , s. 124-127
-
Konferensbidrag (refereegranskat)abstract
- The aim of this study was to compare concentration measurements of uric acid (UA) removed during dialysis. Algorithms based on ultraviolet (UV) absorbance and 1st derivate of UV-absorbance whereby single and multi-wavelength was used. Ten uremic patients from Tallinn and ten from Linköping, during 30+40 haemodialysis treatments, were followed at the Departments of Dialysis and Nephrology at North-Estonian Medical Centre and at Linköping University Hospital. The dialysate samples were taken and analyzed by means of UA concentration at the chemical laboratory and with a double-beam spectrophotometer. UV absorbance and derivate of UV absorbance value on single or multi wavelength was transformed into UA concentration in the spent dialysate using the regression models from the total material, noted as UV-absorbance (UV_A _single and UV_A_multi) and the 1st derivate of UV absorbance (UV_D_single and UV_D_multi) method. Concentrations of UA from the different methods were finally compared regarding mean values and SD. Mean concentration of UA were 52,40 ± 23,1 micromol/l measured at the chemical laboratory (UA_Lab), 52,39 ± 21,8 micromol/l determined by UV_A_single, 52,42 ± 22,4 micromol/ l determined by UV_A_multi and 52,4 ± 22,2 micromol/l determined by UV_D_single and 52,4 ± 22,9 micromol/l determined by UV_D_multi. The results of mean concentrations were not significantly different (p ≥ 0,95). The systematic errors were -0,7- -2,6% and random errors were 8 - 16 % using different methods. The systematic and random errors were significantly different (p < 0.05) between different algorithms indicating that the algorithm that uses multi wavelengths from derivative spectra enables more accurate UA estimation. Our study indicates that the removed UA can be reliably and more accurately estimated by the UV_D_multi technique.
|
|
| 35. |
|
|
| 36. |
- Jerotskaja, Jana, et al.
(författare)
-
Optical Online Monitoring of Uric Acid Removal during Dialysis
- 2010
-
Ingår i: BLOOD PURIFICATION. - : S. Karger AG. - 0253-5068 .- 1421-9735. ; 29:1, s. 69-74
-
Tidskriftsartikel (refereegranskat)abstract
- This study estimates the total removal of uric acid (TRUA) by online UV absorbance measurements in the spent dialysate in two different dialysis centers in Estonia and Sweden. Sixteen dialysis patients were included. All dialysate was collected that gave the reference for TRUA. Two regression models were investigated: one for each patient (UV1) and one for the entire material (UV2). TRUA from the three methods was in the same order but showed a statistically significant difference when the UV2 model was built on data from both centers together. TRUA, (n = 56) was (mean +/- SD, mu mol): 5,854 +/- 1,377 for reference, 6,117 +/- 1,795 for UV1 and 5,762 +/- 1,591 for UV2. Six patients were monitored 1 year after the first study session, using the same models as the previous year, still having a nonsignificant difference. The results show the possibility of estimating TRUA by using UV absorbance. The method appeared to be reliable also in long-term patient monitoring.
|
|
| 37. |
- Lindberg, Lars-Göran, 1951-, et al.
(författare)
-
Non-invasive optical dialysate monitoring
- 1999
-
Ingår i: Congress of the European Renal Association, European Dialysis and Transplant Association,1999.
-
Konferensbidrag (refereegranskat)
|
|
| 38. |
- Paats, Joosep, et al.
(författare)
-
Serum Levels and Removal by Haemodialysis and Haemodiafiltration of Tryptophan-Derived Uremic Toxins in ESKD Patients
- 2020
-
Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 21:4
-
Tidskriftsartikel (refereegranskat)abstract
- Tryptophan is an essential dietary amino acid that originates uremic toxins that contribute to end-stage kidney disease (ESKD) patient outcomes. We evaluated serum levels and removal during haemodialysis and haemodiafiltration of tryptophan and tryptophan-derived uremic toxins, indoxyl sulfate (IS) and indole acetic acid (IAA), in ESKD patients in different dialysis treatment settings. This prospective multicentre study in four European dialysis centres enrolled 78 patients with ESKD. Blood and spent dialysate samples obtained during dialysis were analysed with high-performance liquid chromatography to assess uremic solutes, their reduction ratio (RR) and total removed solute (TRS). Mean free serum tryptophan and IS concentrations increased, and concentration of IAA decreased over pre-dialysis levels (67%, 49%, -0.8%, respectively) during the first hour of dialysis. While mean serum total urea, IS and IAA concentrations decreased during dialysis (-72%, -39%, -43%, respectively), serum tryptophan levels increased, resulting in negative RR (-8%) towards the end of the dialysis session (p < 0.001), despite remarkable Trp losses in dialysate. RR and TRS values based on serum (total, free) and dialysate solute concentrations were lower for conventional low-flux dialysis (p < 0.001). High-efficiency haemodiafiltration resulted in 80% higher Trp losses than conventional low-flux dialysis, despite similar neutral Trp RR values. In conclusion, serum Trp concentrations and RR behave differently from uremic solutes IS, IAA and urea and Trp RR did not reflect dialysis Trp losses. Conventional low-flux dialysis may not adequately clear Trp-related uremic toxins while high efficiency haemodiafiltration increased Trp losses.
|
|
| 39. |
- Paats, Joosep, et al.
(författare)
-
Time-averaged concentration estimation of uraemic toxins with different removal kinetics: a novel approach based on intradialytic spent dialysate measurements
- 2023
-
Ingår i: Clinical Kidney Journal. - : OXFORD UNIV PRESS. - 2048-8505 .- 2048-8513. ; 16:4, s. 735-744
-
Tidskriftsartikel (refereegranskat)abstract
- Background Kt/V-urea is the most used marker to estimate dialysis adequacy; however, it does not reflect the removal of many other uraemic toxins, and a new approach is needed. We have assessed the feasibility of estimating intradialytic serum time-averaged concentration (TAC) of various uraemic toxins from their spent dialysate concentrations that can be estimated non-invasively online with optical methods. Methods Serum and spent dialysate levels and total removed solute (TRS) of urea, uric acid (UA), indoxyl sulphate (IS) and beta 2-microglobulin (beta 2M) were evaluated with laboratory methods during 312 haemodialysis sessions in 78 patients with four different dialysis treatment settings. TAC was calculated from serum concentrations and evaluated from TRS and logarithmic mean concentrations of spent dialysate (MlnD). Results Mean (+/- standard deviation) intradialytic serum TAC values of urea, UA, beta 2M and IS were 10.4 +/- 3.8 mmol/L, 191.6 +/- 48.1 mu mol/L, 13.3 +/- 4.3 mg/L and 82.9 +/- 43.3 mu mol/L, respectively. These serum TAC values were similar and highly correlated with those estimated from TRS [10.5 +/- 3.6 mmol/L (R-2 = 0.92), 191.5 +/- 42.8 mu mol/L (R-2 = 0.79), 13.0 +/- 3.2 mg/L (R-2 = 0.59) and 82.7 +/- 40.0 mu mol/L (R-2 = 0.85)] and from MlnD [10.7 +/- 3.7 mmol/L (R-2 = 0.92), 191.6 +/- 43.8 mu mol/L (R-2 = 0.80), 12.9 +/- 3.2 mg/L (R-2 = 0.63) and 82.2 +/- 38.6 mu mol/L (R-2 = 0.84)], respectively. Conclusions Intradialytic serum TAC of different uraemic toxins can be estimated non-invasively from their concentration in spent dialysate. This sets the stage for TAC estimation from online optical monitoring of spent dialysate concentrations of diverse solutes and for further optimization of estimation models for each uraemic toxin.
|
|
| 40. |
- Tomson, Ruth, et al.
(författare)
-
Development of a method for optical monitoring of creatinine in the spent dialysate
- 2011
-
Ingår i: Estonian Journal of Engineering. - : Estonian Academy Publishers. - 1736-6038 .- 1736-7522. ; 17:2, s. 140-150
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to develop a method suitable for the estimation of the amount of creatinine, removed during dialysis through UV-absorbance. Sixteen uremic patients, seven females and nine males, on chronic thrice-weekly hemodialysis were included in the study. Double-beam spectrophotometer was used for the determination of UV-absorbance in the collected spent dialysate samples. Due to differences in independent variables, two multi-wavelength models (m1 and m2) were developed using stepwise regression, utilizing creatinine values from the laboratory as the dependent parameter. The coefficient of determination, R2 was 0.8690 for the first and 0.9103 for the second model. The systematic error, estimated as BIAS, was zero for both models compared to the creatinine values from the laboratory. The standard errors were 10.06 µmol/l and 15.24 µmol/l for m1 and m2, respectively. The average reduction ratio (RR) from creatinine blood values was 59.8 ± 5.4% (N = 50), average RR from m1 was 63.7 ± 7.3% (N = 50) and average RR from m2 was 64.8 ± 6.4% (N = 48). In summary, the amount of creatinine removed as well as the reduction ratio of creatinine during dialysis can be estimated with UV-absorbance technique.
|
|
| 41. |
- Tomson, R, et al.
(författare)
-
Development of the model for the optical monitoring of urea in spent dialysate
- 2012
-
Ingår i: Electronics Conference (BEC), 2012. - 9781467327756 ; , s. 179-182
-
Konferensbidrag (refereegranskat)abstract
- The aim of the study was to develop a mathematical model suitable for the estimation of urea concentration removed during dialysis through UV-absorbance. 29 haemodialysis patients on chronic three-times-a-week haemodialysis were studied in 6 separate studies. Double-beam spectrophotometer was used for the determination of UV-absorbance in the collected spent dialysate samples. A single wavelength (SW) and a multi-wavelength (MW) model were developed using stepwise regression utilizing urea values from the laboratory as the dependent parameter. For SW model R2 was 0.656 (calibration set) and 0.729 (validation set), for MW model R2 was 0.696 and 0.764, respectively. In summary, the urea concentration removed during dialysis can be estimated with UV-absorbance technique.
|
|
| 42. |
- Tomson, R, et al.
(författare)
-
Development of the Model for the Optical Multiwavelength Monitoring of Creatinine in the Spent Dialysate
- 2010
-
Ingår i: Proceedings of the 12th Biennial Baltic Electronics Conference: 12th Biennial Baltic Electronics Conference, Tallinn, Estonia, October 4 - 6, 2010, ISSN: 1736-3705. - 9781424473564 ; , s. 261-264
-
Konferensbidrag (refereegranskat)abstract
- The aim of the study was to develop a statistical model suitable for the estimation of creatinine concentration removed during dialysis through UV-absorbance. Ten uremic patients, three females and seven males, mean age 62.6 ± 18.6 years, on chronic thrice-weekly hemodialysis were included in the study. Double-beam spectrophotometer (Shimatsu UV-2401 PC, Japan) was used for the determination of UV-absorbance in the collected spent dialysate samples. Due to differences in independent variables included two multiwavelength models were developed using stepwise regression. The coefficient of determination, R2 was 0.8709 for the first and 0.8756 for the second model. The standard errors were 15.86 micromol/l and 16.01 micromol/l, respectively. In summary, the creatinine concentration removed during dialysis can be estimated with UV-absorbance technique.
|
|
| 43. |
- Tomson, Ruth, et al.
(författare)
-
Optical measurement of creatinine in spent dialysate
- 2013
-
Ingår i: Clinical Nephrology. - 0301-0430. ; 79:2, s. 107-117
-
Tidskriftsartikel (refereegranskat)abstract
- Aim: The aim of the study was to develop an optical method for the estimation of creatinine (Cr) removal during dialysis using UV-absorbance. Material and methods: 29 hemodialysis patients on chronic 3-times-a-week hemodialysis were studied in 6 separate studies. Double-beam pectrophotometer was used for the determination of UV-absorbance in the collected spent dialysate samples. A single wavelength (SW) and a multi-wavelength (MW) model were developed using stepwise regression utilizing Cr values from the laboratory as the dependent parameter. The reduction ratio (RR) and total removed Cr (TRCr) were estimated. Results: For blood-Cr RRb (mean ± SD) was 60.9 ± 5.0% (calibration set) and 58.1 ± 6.0% (validation set), for SW UVabsorbance RR_SW was 61.5 ± 5.9% and 57.3 ± 6.0%, and for MW UV-absorbance RR_MW was 65.8 ± 5.8% and 61.7 ± 6.4% respectively. RR_SW and RRb were not statistically different. RR_MW was higher compared to RRb (p < 0.05). TRCr_lab was 13.8 ± 3.8 mmol, TRCr_SW 14.5 ± 2.5 mmol and TRCr_MW 13.8 ± 2.6 mmol, being not statistically different. Conclusion: In summary, creatinine removal during dialysis can be estimated as reduction ratio and total removed creatinine with the UV-absorbance technique.
|
|
| 44. |
- Tomson, Ruth, et al.
(författare)
-
Urea rebound assessment based on UV-absorbance in spent dialysate
- 2014
-
Ingår i: ASAIO journal (1992). - : Lippincott Williams & Wilkins. - 1058-2916 .- 1538-943X. ; 60:4, s. 459-465
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to examine the possibility of post-dialysis urea rebound assessment using UV-absorbance measurements in spent dialysate. Twenty-six patients on chronic three-times-a-week hemodialysis (HD) were studied in two separate studies. Double-beam spectrophotometer was used for the determination of UV absorbance in the collected spent dialysate samples. Also, on-line UV absorbance was monitored. The equilibrium concentration (C-eq) of urea at the end of the rebound phase was calculated based on urea concentration in blood and dialysate and UV absorbance in spent dialysate. Based on C-eq, urea rebound was expressed relative to urea concentration at the end of HD (R-1) and relative to the decrease in urea concentration during HD (R-2). Estimates based on UV-absorbance values in spent dialysate (R-1_a, R-2_a) slightly over assess postdialysis rebound compared with results based on the blood sample drawn 30 min after HD (R-1_30post, R-2_30post), but R-1_a and R-2_a presented greater consistency and accuracy compared with the estimates based on the intradialytic blood sample (R-1_b, R-2_b). In summary, the results show that it is possible to assess postdialysis urea rebound in blood based on UV-absorbance measurements in spent dialysate.
|
|
| 45. |
|
|
| 46. |
|
|
| 47. |
- Uhlin, Fredrik, et al.
(författare)
-
Dialysis dose (Kt/V) and clearance variation sensitivity using measurement of ultraviolet-absorbance (on-line), blood urea, dialysate urea and ionic dialysance
- 2006
-
Ingår i: Nephrology Dialysis Transplantation. - : Oxford University Press (OUP). - 0931-0509 .- 1460-2385. ; 21:8, s. 2225-2231
-
Tidskriftsartikel (refereegranskat)abstract
- Background. An on-line monitoring system for dialysis dose calculations could make it possible to provide an adequate dialysis dose that is consistently given to haemodialysis (HD) patients. The aim of this study was to compare dialysis dose (Kt/V) using four different methods and their sensitiveness to a reduction in clearance. Methods. Six patients were monitored on-line with ultraviolet (UV)-absorbance at a wavelength of 297 nm in three consecutive dialysis sessions during 1 week. During the last treatment, the clearance was reduced by 25% by decreasing the blood flow. For the determination of UV-absorbance, a spectrophotometer was connected to the fluid outlet of the dialysis machine with all spent dialysate passing through a flow cuvette. The equilibrated Kt/V (eKt/V) estimated by UV-absorbance was compared with eKt/V from the ionic dialysance method using the on-line clearance monitor (OCM) and the appurtenant software dose-calculation tool DCTool (Fresenius Medical Care, Germany), eKt/V calculated from the dialysate-urea slope and with eKt/V from pre- and post-dialysis blood-urea samples as reference. Results. The study demonstrates that the sensitiveness to clearance reduction is similar in the four methods compared for eKt/V. When the different methods were compared, the mean eKt/V of UV-absorbance was 1.21 ± 0.20, blood 1.30 ± 0.21, dialysate 1.32 ± 0.21 and OCM (using the DCTool) 1.31 ± 0.21. The standard deviation was of the same magnitude. Conclusion. The UV-method gives a similar response to clearance reduction compared with the other methods when comparing dialysis dose. The high sampling rate by continuous monitoring of UV-absorbance allows evaluation of the clearance process during dialysis and gives immediate feedback to on-line adjustments.
|
|
| 48. |
- Uhlin, Fredrik, et al.
(författare)
-
Estimating total urea removal and protein catabolic rate by monitoring UV absorbance in spent dialysate
- 2005
-
Ingår i: Nephrology Dialysis Transplantation. - : Oxford University Press (OUP). - 0931-0509 .- 1460-2385. ; 20:11, s. 2458-2464
-
Tidskriftsartikel (refereegranskat)abstract
- Background. Dialysate-based, on-line measurements of Kt/V and protein catabolic rate (PCR) in dialysis patients have been considered more accurate compared with measurements on the blood side during dialysis. The primary aim of this study was to compare total removed urea (TRU) and PCR, normalized to body weight (nPCRw), obtained by three dialysate-based methods: (i) on-line ultraviolet (UV) absorbance of the spent dialysate; (ii) total dialysate collection (TDC), as reference method; and (iii) Urea Monitor 1000 (UM) from Baxter Healthcare Corp. Methods. We studied 10 uraemic patients on chronic, thrice-weekly haemodialysis. We made absorption measurements (UV radiation) on-line with a spectrophotometer connected to the fluid outlet of the dialysis machine, with all spent dialysate passing through an optical cuvette for single-wavelength measurements. UV absorbance measurements were compared with TDC and the UM. Results. nPCRw obtained with UV absorbance was 0.82±0.17, that from TDC 0.81±0.18, and that measured by UM 0.87±0.18, which was significantly higher than the results of the other methods. The difference between nPCRw calculated by TDC and by UM was –0.05±0.06, showing a slightly lower SD than the difference between nPCRw by TDC and UV absorbance, –0.01±0.07. Conclusion. The study demonstrates that TRU, and consequently PCR, can be estimated by on-line measurement of the UV absorption in the spent dialysate.
|
|
| 49. |
- Uhlin, Fredrik, et al.
(författare)
-
Estimation of delivered dialysis dose by on-line monitoring of the ultraviolet absorbance in the spent dialysate
- 2003
-
Ingår i: American Journal of Kidney Diseases. - 0272-6386 .- 1523-6838. ; 41:5, s. 1026-1036
-
Tidskriftsartikel (refereegranskat)abstract
- Background:Several methods are available to determine Kt/V, from predialysis and postdialysis blood samples to using on-line dialysate urea monitors or to ionic dialysance using a conductivity method. The aim of this study is to compare Kt/V calculated from the slope of the logarithmic on-line ultraviolet (UV) absorbance measurements, blood urea Kt/V, dialysate urea Kt/V, and Kt/V from the Urea Monitor 1000 (UM; Baxter Healthcare Corp, Deerfield, IL).Methods:Thirteen uremic patients on chronic thrice-weekly hemodialysis therapy were included in the study. The method uses absorption of UV radiation by means of a spectrophotometric set-up. Measurements were performed on-line with the spectrophotometer connected to the fluid outlet of the dialysis machine; all spent dialysate passed through a specially designed cuvette for optical single-wavelength measurements. UV absorbance measurements were compared with those calculated using blood urea and dialysate urea, and, in a subset of treatments, the UM.Results:Equilibrated Kt/V (eKt/V) obtained with UV absorbance (eKt/Va) was 1.19 ± 0.23; blood urea (eKt/Vb), 1.30 ± 0.20, and dialysate urea (eKt/Vd), 1.26 ± 0.21, and Kt/V in a subset measured by the UM (UM Kt/V) was 1.24 ± 0.18. The difference between eKt/Vb and eKt/Va was 0.10 ± 0.11, showing a variation similar to the difference between eKt/Vb and eKt/Vd (0.03 ± 0.10) and in a subset between eKt/Vb and UM Kt/V (−0.02 ± 0.11).Conclusion:The study suggests that urea Kt/V can be estimated by on-line measurement of UV absorption in the spent dialysate.
|
|
| 50. |
|
|
