Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
  • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
  • G01N21/33—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using ultraviolet light
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/85—Investigating moving fluids or granular solids
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
  • G01N21/03—Cuvette constructions
  • G01N21/05—Flow-through cuvettes

Definitions

• This invention relates to a novel method and a device for measuring and monitoring quantitatively concentrations of substances in a biological fluid and removal of uremic retention solutes utilizing UV-absorbance measurements during dialysis. More specifically, the present invention relates to an optical method utilizing optical spectrum, preferable UV- spectrum and UV-absorbance, preferable UV-absorbance of the spent dialysate, and a specific model, including a unique set of optical spectral components at certain wavelengths, to determine and to monitor, preferable on-line, the concentration and removal of the hardly diffusible uremic retention solutes like protein bound uremic toxins and middle molecules such as beta2-microglobulin (B2M) or easily diffusible uremic retention solutes like urea, creatinine or urea acid having small molecular weight.
• B2M beta2-microglobulin
• the uremic syndrome is attributed to the progressive retention of a large number of compounds, which under normal conditions are excreted by healthy kidneys. These compounds are called uremic retention solutes, or uremic toxins, when they interact negatively with biologic functions.
• the uremic syndrome is a complex principle favorintoxication" of the retention of waste products resulting in multifactorial problems where disturbances in several metabolic functions are reflected in clinical problems.
• organs and organ systems are affected: cardio-vascular system (hypertension, pericarditis and heart failure), peripheral nervous system (polyneuropathy), central nervous system (poor memory, loss of concentration and slower mental ability), hematology (anemia, bleeding tendencies), coagulation, immune status (immunosupression), nausea, vomiting etc.
• uremic toxins are divided into three groups: 1) small molecules (MW ⁇ 500 Da); 2) middle molecules (MW > 500 Da); 3) protein-bound solutes.
• uremic toxins have effect to the patient by many different ways and extent, and to ensure the best survival, quality of the treatment and the quality of life for the dialysis patients monitoring of several uremic toxins is essential.
• Small molecular weight solutes (MW ⁇ 500 g/mol): urea, creatinine, uric acid, guanidine - ADMA (asymmetric dimethylarginine), phosphate.
• Urea is a small, water soluble molecule with a molecular weight of 60 Da.
• Urea is the major end product of protein nitrogen metabolism in humans. It constitutes the largest fraction of the non - protein nitrogen component of the blood. Urea is produced in the liver and excreted through the kidneys in the urine. Consequently, the circulating levels of urea depend upon protein intake, protein catabolism and kidney function. Elevated urea levels can occur with dietary changes, diseases which impair kidney function, liver disease, congestive heart failure, diabetes and infection.
• the most common method for urea determination is the enzymatic method by the enzyme urease.
• urea is hydrolyzed in the presence of water and urease to produce ammoniaand carbon dioxide.
• GLDH glutamate dehydrogenase
• NADH reduced nicotinamide adenine dinucleotide
• the reaction is monitored by measuring the rate of decrease in absorbance at 340 nm as NADH is converted to NAD.
• the calculations are based on the discovery of Tiffany, et al. that urea concentration is proportional to absorbance change over a fixed time interval.
• Creatinine is a de-composition by product of the energy producing compound, creatine phosphate.
• the amount of creatinine produced is fairly constant and is primarily a function of muscle mass. Creatinine is removed from the plasma by glomerular filtration and then excreted in the urine without any appreciable re-absorption by the tubules. Typically 7-10% of creatinine in the urine is derived from tubular secretion but this is increased in the presence of renal insufficiency. Because creatinine is endogenous and is freely filtered at the glomerulus, it is widely used to assess kidney function (Glomerular Filtration Rate or GFR) and is expressed either as a plasma concentration or renal clearance.
• GFR Gelular Filtration Rate
• Creatinine can be determined in several different ways: 1) Jaffe method [2]; 2) enzymatic colourimetric method.
• Jaffe method testing utilizes picric acid for the Jaffe Reaction to test for creatinine. It forms a colored bright orange-red complex that can be measured using spectroscopy.
• the enzymatic colourimetric determination of creatinine which largely eliminates interferences known to the Jaffe method.
• the series of enzyme catalyzed reactions involved in the assay system are as follows: firstly, the potential interference from endogenous creatine and sarcosine are eliminated by the reaction of creatine amidinohydrolase, sarcosine oxidase and catalase before creatinine is determined.
• the formation of the quinoneimine dye product results in an increase in absorbance at 550nm (530-570nm) which is directly proportional to the creatinine concentration in the sample.
• Ascorbate oxidase eliminates the influence of ascorbate in the sample.
• the demerits of the abovementioned methods to determine urea and creatinine include: 1) some compounds similar to urea and creatinine contained in the sample of biological fluid may affect the test accuracy; 2) the operation is complex, needs lots of agents which are hard to keep, and should be operated by professionals; 3) the sample must be de-protein pretreated; and 4) the necessary equipment is expensive.
• Uric acid a final product of the metabolism of purine, is very important biological molecule present in body fluids. It is mostly excreted from human body through the kidneys in the form of urine. The concentration of uric acid in blood increases when the source of uric acid increases or the kidney malfunctions. Hyperuricemia is a symptom when the uric acid concentration is above 7 mg/dL. Uric acid is hard to dissolve in blood and will crystallize when supersaturated. The uric acid crystallites deposit on the surface of skin, in joints, and especially in toes and results in gout. The analysis of the uric acid concentration in blood helps to diagnose gout.
• hyperuricemia In addition to gout, hyperuricemia is connected with lymph disturbance, chronic hemolytic anemia, an increase of nucleic acid metabolism and kidney malfunction. Elevated serum UA contributes to endothelial dysfunction and increased oxidative stress within the glomerulus and the tubulo-interstitium, with associated increased remodeling fibrosis of the kidney [3].
• a high level of serum UA, hyperuricemia has been suggested to be an independent risk factor for cardiovascular and renal disease especially in patients with heart failure, hypertension and/or diabetes [4-6] and has been shown to cause renal disease in a rat model [7].
• UA is mostly associated with gout but studies have implicated that UA affects biological systems [8] and also could influence risks of higher mortality in dialysis patients [9] but the pathogenic role of hyperuricemia in dialysis patients is not complete established [10]. High caloric foods and alcohol as well as disturbances of organs and tissues are the main causes of hyperuricemia and even gout. Harm can be prevented and reduced by an early diagnosis and monitoring.
• a simple and inexpensive detecting system helps patients to detect the uric acid concentration on their own.
• a method and apparatus for the quantitative determination of optically active substances, particularly uric acid, by UV-absorbance is proposed in WO2009071102 (US60/992156, 04.12.2007), Ivo Fridolin, et al.
• Uric acid can be determined in several different ways. Two of the most common methods are (1) reduction method by the reaction of uric acid with alkaline phosphotungstate, and (2) the enzymatic method by the enzyme urease.
• uric acid is estimated by reducing alkaline phosphotungstate to tungsten blue and measuring the colored product in a colorimeter.
• the demerits of this method include: 1) some compounds similar to uric acid and ascorbic acid contained in the sample of biological fluid affect the test accuracy; 2) the operation is complex, needs lots of agents which are hard to keep, and should be operated by professionals; 3) the sample must be de- protein pretreated; and 4) the necessary equipment is expensive.
• the second method detects uric acid by optical colorimetry and electrochemistry and is classified into uricase-ultraviolet absorption, uricase-peroxidase, uricase-catalase and uricase-electrode methods, wherein the former three methods make use of the color of reaction products and quantitatively detect uric acid of by colorimetry.
• the decrease in absorbance is proportional to the amount of uric acid initially present.
• the automatic bio- analyzers used in central bio-laboratories of hospitals detect uric acid by optical colorimetry.
• An improving system for quantification of biochemical components in biological fluids during analysis where a component reacts with aft analyte is described in US6121050, 19.09.2000 HAN, CHI-NENG ARTHUR.
• the blood sample should be pretreated to be serum or plasma first.
• the merits of the automatic bio-analyzers reside in mass detecting, automation and quickness.
• an automatic bio-analyzer cannot be applied in household detecting because it requires professionals to operate, is expensive, and is particularly hard to store the detecting agents.
• the uricase-electrode method detects uric acid by electrochemistry.
• the electrodes can be divided as enzymatic and non-enzymatic.
• the former produced by a complex production process is hard to store and thus is only suitable for research.
• the blood sample should be pretreated to be serum or plasma first.
• the merits of the automatic bio-analyzers reside in mass detecting, automation and quickness.
• an automatic bio-analyzer cannot be applied in real-time and household detecting because it requires professionals to operate, is expensive, and is particularly hard to store the detecting agents.
• Middle molecules (MW > 500 g/mol): P2-microglobulin, cytokines (interleukin 6), parathyroid hormon (PTH) - (at the same time belongs to the protein-bound group).
• Protein-bound solutes indoxyl sulfate, homocysteine, p-cresol, AGE products, hippuric acid.
• B2M ⁇ 2 -microglobulin (B2M) (MW 1 1 818 D) is the light chain of HLA class I complex and as such is expressed on all nucleated cells.
• B2M is normally found in low concentrations in the plasma. In end stage renal failure its concentration increases markedly secondary to reduced renal elimination. Uremia-related amyloid is to a large extent composed of B2M and is essentially found in the osteoarticular system and in the carpal tunnel. Uremia related amyloidosis becomes clinically apparent after several years of chronic renal failure and/or in the aged. B2M has become a frequently used marker for the dialytic removal of middle molecules. Behavior of B2M during dialysis is, however, not necessarily representative of that of other middle molecules. Hemodialysis with large pore membranes results in a progressive decrease of predialysis B2M concentrations and in a lower prevalence of dialysis-related amyloidosis and/or carpal tunnel syndrome.
• B2M is mainly determined by ELISA assay method.
• the method is automated as an automatic bio-analyzer, the merits of the ELISA itself reside in mass detecting discrepancy and complicacy of the method. It cannot be applied in routine or household detecting because it requires professionals to operate, is expensive, and there is hard to store the detecting agents. Great care has been taken to ensure the quality and reliability of the method but however, it is possible that in certain cases unusual results may be obtained due to high levels of interfering factors.
• HPLC high performance reverse liquid chromatography
• indoxyl sulfate has been determined by fluorescence detection (excitation 280 nm, emission 340 nm)
• hippuric acid has been analyzed by ultraviolet detection at 254 nm in the serum and in the spent dialysate (Dhondt, Vanholder et al. 2003) [14].
• the demerits of this method include: 1) separation of the compounds may be difficult due to similar properties which affects the test accuracy; 2) the operation is complex, needs lots of agents and should be operated by professionals; 3) the sample needs pretreatment for deproteinization; and 4) the necessary equipment is expensive.
• the merits of the described method are that it does not need blood samples, no disposables or chemicals, and is fast.
• the described method is general and does not specify methodology to measure exclusively a single compound and is meant to apply only for dialysis monitoring. Moreover, no results about the concentration measurements are presented. More exact description about the uric acid and urea measurements using the abovementioned method is given in a scientific papers (Uhlin, Lindberg et al. 2005) [21], (Uhlin, Fridolin et al. 2005) [20].
• Another method relates to a method for dialysis monitoring method and apparatus using near infrared radiation, described in W09819592, 14.05.1998, RIO GRANDE MEDICAL TECH INC.
• the merits of the described method are similar to that of the UV-radiation.
• the described method measures urea and creatinine by utilizing near infrared radiation spectrometry with different technical and optical considerations.
• near infrared radiation spectrometry the principial component analysis using calibration and prediction stage is described in US5886347.
• Another method, described in RU2212029, 10.09.2003, VASILEVSKIJ A M et al relies on the Beer-Lambert law and utilizes the millimolar extinction coefficients of the components in the spent dialysate.
• the example given in this invention describes concentration determination of urea, phosphate, creatinine and uric acid.
• the example is given only for one dialysis session which is a serious limitation and can not be applied for the general use.
• urea and phosphate do not absorb UV-radiation as incorrectly claimed in this application, and thus concentration measurement of urea and phosphate is impossible using this invention.
• concentration measurement of creatinine is not applicable using the Beer- Lambert law.
• LBM Lean Body Mass
• a new, simplified mapping of dialysis dose and nutrition is proposed by using only two parameters - Kt/V and nPNA, suitable for automatic and time-efficient way to review the performed HD strategy based on the data from on-line dialysate side dialysis monitors.
• the abovementioned novel method for quantitative concentration measurements of uremic retention solutes in the biological fluids combined with the new, simplified mapping of dialysis dose and nutrition, gives an added value for the real-time, automatic monitoring of dialysis patients.
• the purpose of the invention is, therefore, a new method and a device for measuring concentration of substances (e.g. middle molecular weight solutes - (MM) (MW > 500 g/mol): p2-microglobulin, Cytokines (Interleukin 6), Parathyroid hormon (PTH) - at the same time belongs to the protein-bound group, small molecular weight solutes - (MW ⁇ 500 g/mol): Urea, Creatinine, Uric acid, Guanidine -ADMA (asymmetric dimethylarginine), Phosphate) in biological fluids and monitoring removal of the said hardly and easily diffusible uremic retention solutes during dialysis.
• substances e.g. middle molecular weight solutes - (MM) (MW > 500 g/mol): p2-microglobulin, Cytokines (Interleukin 6), Parathyroid hormon (PTH) - at the same time belongs to the protein-bound group, small molecular weight
• the present invention relates to an optical method utilizing optical spectrum of the biological fluids and UV- absorbance, preferable UV-absorbance of the spent dialysate or the peritoneal liquid, and concentration calculation algorithm containing the transforming function to determine on the samples or on-line the concentration of the substances, which can be effected directly at the bed-side, real-time and which avoids the disadvantages caused by the analysis in a laboratory.
• the method and device determines the concentration of the substances in-vitro or on-line utilizing a measuring cuvette (cell) suitable for specified measurements.
• Another object of the present invention is to provide a novel and practical optical urea and creatinine measuring method and device which determines quantitatively concentration of the forementioned water soluble small molecular weight substances in the spent dialysate. Those concentration values can be represented directly and easily on the monitor or screen printed.
• the novel method and device does not require any chemical disposables, and can be easily made and mass-produced providing an environment-friendly optical method.
• Another object of the present invention is to provide a practical optical method and device determining quantitatively concentration or removal of the middle molecules and protein bound uremic toxins in the biological fluids. The determined values can be represented directly and easily on the monitor or screen printed.
• the method and device does not require any chemical disposables, neither expensive separation techniques, and can be easily made and mass-produced providing an environment-friendly optical method.
• a still further object of the present invention is to provide a method for assessing routine clinical monitoring in order to face risks of higher mortality in patients (e.g. in dialysis).
• a still further object of the present invention is to provide a novel, rapid, convenient and safe method for detecting concentration of substances in a liquid sample.
• the liquid sample can be directly dropped on the detecting cuvette for in-vitro measurements or sent a flowing stream of fluid through a flow-through cell for on-line monitoring.
• the method is suitable for household use when being applied to detect the concentration of substances in the biological fluids.
• Fig. 1 shows a block diagram of one embodiment of the invention.
• Fig. 2 shows a block diagram of another embodiment of the invention applied for substances in a biological fluid during dialysis.
• Fig. 3 shows the linear relationship between urea concentration measured by the known method (Predicted) and at the laboratory (Expected) for the "Calibration" group.
• Fig. 4 shows the linear relationship between the urea concentration estimated by the new method (Predicted) and at the laboratory (Expected) for the "Calibration” group.
• Fig. 5 shows the linear relationship between the urea concentration estimated by the known method (Predicted) and at the laboratory (Expected) for the "Validation" group.
• Fig. 6 shows the linear relationship between the urea concentration estimated by the new method (Predicted) and at the laboratory (Expected) for the "Validation" group.
• Fig. 7 shows the linear relationship between creatinine concentration measured by the known method (Predicted) and at the laboratory (Expected) for the "Calibration” group.
• Fig. 8 shows the linear relationship between creatinine concentration measured by the new method (Predicted) and at the laboratory (Expected) for the "Calibration” group.
• Fig. 9 shows the linear relationship between creatinine concentration estimated by the known method (Predicted) and at the laboratory (Expected) for the "Validation” group.
• Fig. 10 shows the linear relationship between creatinine concentration estimated by the new method (Predicted) and at the laboratory (Expected) for the "Validation” group.
• Fig. 11 shows the linear relationship between the uric acid concentration measured by the known method (Predicted) and at the laboratory (Expected) for the "Calibration” group.
• Fig. 12 shows the linear relationship between uric acid concentration measured by the new A method (Predicted) and at the laboratory (Expected) for the "Calibration” group.
• Fig. 13 shows the linear relationship between uric acid concentration measured by the new B method (Predicted) and at the laboratory (Expected) for the "Calibration" group.
• Fig. 14 shows the linear relationship between the uric acid concentration estimated by the known method (Predicted) and at the laboratory (Expected) for the "Validation” group.
• Fig. 15 shows the linear relationship between the uric acid concentration estimated by the new A method (Predicted) and at the laboratory (Expected) for the "Validation” group.
• Fig. 16 shows the linear relationship between the uric acid concentration estimated by the new B method (Predicted) and at the laboratory (Expected) for the "Validation” group.
• Fig. 14 shows the linear relationship between the uric acid concentration estimated by the known method (Predicted) and at the laboratory (Expected) for the "Validation” group.
• Fig. 15 shows the linear relationship between the uric acid concentration estimated by the new A method (Predicted) and at the laboratory (Expected) for the "Validation” group.
• Fig. 16 shows the linear relationship between the uric acid concentration estimated by the new B method (Predicted)
• 17 shows a new, simplified mapping of dialysis dose and nutrition applied by using only two parameters - Kt/V and nPNA, suitable for automatic and time-efficient way to review the performed HD strategy based on the data from on-line dialysate side dialysis monitor.
• Fig. 18 shows an example to estimate a parameter Lean Body Mass (LBM), suitable for automatic and time-efficient way to review the muscle mass and protein nutritional status of the HD patients based on the data from on-line dialysate dialysis monitor as comparison between the known blood based (LBM b) and the novel UV-absorbance method (LBM_uv).
• LBM Lean Body Mass
• Fig. 20 shows the linear relationship between the B2M concentration in the spent dialysate estimated by the UV absorbance at 314 nm (Predicted) and at the laboratory (Expected) for the total material.
• Fig. 1 shows a block diagram of one embodiment of the invention applied for determining content of the hardly or easily diffusible uremic retention solutes in the biological fluids. Another embodiment of the invention is shown in Fig. 2.
• the device is applied for determining the concentration of substances (uremic retention solutes) in a biological fluid during dialysis in spent dialysate 6.
• the device comprises spectrophotometer 7, a signal processing unit 8 for concentration calculation, a unit 9 for presenting concentration or treatment map 10 of the substance in the spent dialysate.
• the block diagram of the device according to one embodiment of the invention is shown in Fig. 1.
• the device for measuring concentration of a hardly diffusible uremic retention solute 5 in a biological fluid 1 comprises:
• an optical module 2 comprising a spectrophotometrical system, comprising a light source and a light detector;
• a measuring cuvette for holding a sample of the biological fluid so that the light can be led through the sample
• a signal processing module 3 comprising a data acquisition module and a spectra processing module
• the light source can be either a broadband light source or a narrowband light source. If broadband light source is used, either a broadband detector with a filter can be used, or narrowband detectors. According to one embodiment, the optical module is operating in the ultra violet region (wavelength range 190-330 nm).
• the measuring cuvette can be, e.g., adapted for in-vitro measurements, or designed for the on-line measurements.
• the signal or spectra processing module is adapted to utilize the raw UV absorbance values or slope of the natural logarithimic UV absorbance values vs time to execute a dialysis dose calculation algorithm.
• the signal or spectra processing module is adapted to utilize a unique set of optical spectral components at certain wavelengths, adapted to execute a concentration calculation algorithm comprising a transforming function calculating, preferable real-time, the concentration of the uremic retention solutes in the biological fluid.
• the transforming function in order to transform UV-absorbance (dimensionless) into uremic retention solute concentration in mg/L or mmol/L, has the form
• y is a dependent variable (i.e. uremic retention solute concentration in mg/L or mmol/L)
• bO is the intercept
• bi-s are the appropriate regression coefficients
• Al - Ai-s are the measured UV-absorbances at the certain wavelengths
• xi-s are other appropriate variables.
• the data representing module is adapted to execute a program for data representation and comprises or is connected to a data visualization module, e.g., a monitor, a display, or a printing device.
• a data visualization module e.g., a monitor, a display, or a printing device.
• the data visualization module is adapted for a new, simplified mapping of dialysis dose and nutrition is applied by using only two parameters - Kt V and nPNA, suitable for automatic and time-efficient way to review the performed HD strategy based on the data from on-line dialysate side dialysis monitors.
• a group of uremic patients on chronic thrice-weekly hemodialysis were included in the study at the Department of Dialysis and Nephrology.
• the dialysate flow was 500 mL/min and the blood flow varied between 245 to 350 mL/min.
• the type of dialysis machine used was Fresenius 4008H (Fresenius Medical Care, Germany).
• the optical module consisted of a double-beam spectrophotometer (SHIMATSU UV-2401 PC, Japan) with an accuracy of ⁇ 1% on the dialysate samples taken at predetermined times during dialysis. Spectrophotometric analysis over a wavelength range of 190 - 380 nm was performed by a cuvette with an optical path length of 1 cm.
• the data acquisition module consisted of a PC incorporated in the spectrophotometer using UV-PC software (UV-PC personal spectrophotometer software, version 3.9 for Windows).
• the obtained UV-absorbance values were processed and presented by a signal processing module using a known (uniwavelength) algorithm, and the novel (multiwavelength) algorithm by a specially developed application by a concentration calculation algorithm containing the transforming function calculating the concentration of certain substance in the biological fluid.
• the data representing module was either the computer screen or a printer.
• dialysate samples were taken during the dialysis. Pure dialysate was collected before the start of a dialysis session, used as the reference solution, when the dialysis machine was prepared for starting and the conductivity was stable.
• concentrations of the substances such as urea, creatinine and uric acid, were determined at the clinical chemistry laboratory using standardized methods. On the basis of the results the determination coefficient R 2 , systematic error (BIAS) and standard error (SE) were calculated for the known and new method using concentrations from the laboratory as the reference as:
• e is the i-th residual and N is the number of observations.
• the i-th residual was obtained as the difference between laboratory and optically determined parameter values for the i-th measurement.
• the results (see Results) obtained by the closest existing method for determination of the amount of waste products in the dialysis liquid during dialysis treatment described in W09962574, US6666840B1 is referred here as the contextknown method". Those results are compared to the results by the method subject to this invention noted as the contextnew method".
• Including new patients should be the most sensitive because of the possible different combination or composition of the UV-absorbing compounds filtered from the blood into the dialysate during the dialysis may influence the model accuracy. To test a such situation only a part of the patients were included into the "Calibration" group to create a model, and after that new patients not presented before were included into the "Validation” group to validate the model.
• Fig. 3 and Fig. 4 show the linear relationship between urea concentration measured by the known and new method (Predicted) and at the laboratory (Expected) for the "Calibration" group.
• the new method utilises an unique set of optical spectral components at certain wavelengths, to determine, preferable on-line, the concentration of the water soluble small molecular weight substance urea obtained by building up the model on the "Calibration" group.
• the transforming function in order to transform UV-absorbance (dimensionless) into urea concentration [mmol/L], has the form
• Urea (t) [mmol/L] 1.00 + 6.28* A(t, 295nm) - 8.86* A(t, 320nm) - 0.529* A(t, 253nm)
• Urea (t) [mmol/L] is a dependent variable urea concentration in mmol/L at the time moment t
• A(t, ⁇ nm) are the measured variables, i.e. absorbances at certain wavelengths at the time moment t multiplied by the appropriate coefficients.
• Fig. 5 and Fig. 6 show the linear relationship between urea concentration measured by the known and new method (Predicted Urea) and at the laboratory (Expected Urea) for the "Validation" group including the material not included into the model build up.
• Fig. 7 and Fig. 8 show the linear relationship between creatinine concentration measured by the known and new method (Predicted Crea) and at the laboratory (Expected Crea) for the "Calibration" group.
• the R 2 is increased remarkably compared to the known method.
• the new method utilises an unique set of optical spectral components at certain wavelengths, to determine, preferable on-line, the concentration of the water soluble small molecular weight substance creatinine obtained by building up the model on the "Calibration" group.
• the transforming function in order to transform UV-absorbance (dimensionless) into creatinine concentration [mmol/L], has the form
• Crea (t) [mmol/L] 31.7 + 231.2*A(t, 294nm) - 321.3* A(t, 314nm) -72.8* A(t, 283nm)
• Crea (t) [mmol/L] is a dependent variable creatinine concentration in mmol/L)
• A(t, ⁇ nm) are the measured variables, i.e. absorbances at certain wavelengths at the time moment t multiplied by the appropriate coefficients.
• Fig. 9 and Fig. 10 show the linear relationship between creatinine concentration estimated by the known and new method (Predicted Crea) and at the laboratory (Expected Crea) for the "Validation” group.
• the R 2 is increased remarkably utilizing the new method compared to the known method even for the "Validation" group including the material not included into the model build up.
• Fig. 1 1 show the linear relationship between uric acid concentration estimated by the known method (Predicted) and at the laboratory (Expected) for the "Calibration” group.
• Fig. 12 and Fig. 13 show the linear relationship between uric acid concentration estimated by the new methods (A and B) (Predicted) and at the laboratory (Expected) for the "Calibration” group.
• the R 2 is increased utilizing the new method compared to the known method even for the "Calibration" group.
• the new method A utilises an unique set of optical spectral components at certain wavelengths, to determine, preferable on-line, the concentration of the water soluble small molecular weight substance uric acid obtained by utilizing measured UV-absorbance values, and building up the model on the "Calibration" group.
• the transforming function of this method called as “New A method”, in order to transform UV-absorbance (dimensionless) into uric acid concentration [mmol/L], has the form
• UA (t) [mmol/L] is a dependent variable uric acid concentration in mmol/L at the time moment t
• A(t, ⁇ nm) are the measured variables, i.e. absorbances at certain wavelengths at the time moment t multiplied by the appropriate coefficients.
• the new method B utilises an unique set of optical spectral components at certain wavelengths, to determine, preferable on-line, the concentration of the water soluble small molecular weight substance uric acid obtained by utilizing the processed UV- absorbance values by Sawitsky-Golay method, and building up the model on the "Calibration" group.
• the transforming function of this method called as "New B method", in order to transform UV-absorbance (dimensionless) into uric acid concentration [mmol/L], has the form
• A_d(t, ⁇ nm) are the variables (measured and the processed UV-absorbance values by Sawitsky-Golay method), i.e. processed absorbances at certain wavelengths at the time moment t multiplied by the appropriate coefficients.
• Fig. 14 show the linear relationship between uric acid concentration estimated by the known method (Predicted) and at the laboratory (Expected) for the "Validation” group.
• Fig. 15 and Fig. 16 show the linear relationship between uric acid concentration estimated by the new methods (A and B) (Predicted) and at the laboratory (Expected) for the "Validation” group.
• the R 2 is increased remarkably utilizing the new method compared to the known method even for the "Validation" group including the material not included into the model build up.
• Table 3 Summary results for the different methods to measure concentration of the acid.
• Fig. 17 shows a new, simplified mapping of dialysis dose and nutrition applied by using only two parameters - Kt/V and nPNA, suitable for automatic and time-efficient way to review the performed HD strategy based on the data from on-line dialysate side dialysis monitor, utilizing the urea concentration determination method described above.
• Fig. 18 shows an example to estimate a parameter Lean Body Mass (LBM), suitable for automatic and time-efficient way to review the muscle mass and protein nutritional status of the HD patients based on the data from on-line dialysate dialysis monitor as comparison between the known blood based (LBM b) and the novel UV-absorbance method (LBM_uv), utilizing the creatinine concentration determination method described above.
• LBM Lean Body Mass
• the duration of the ol-HDF treatments varied between 180 to 270 minutes, the dialysate flow was 500 mL/min, the blood flow varied between 280-350 mL/min. All patients were dialyzed via artery-venous fistulas using a "two-needle" system.
• the auto sub system mode for calculation of the on-line prepared substitution volume varied between 12.2 to 29.7 liters per session.
• the linear relationship analysis for B2M utilizing UV absorbance values at the wavelength which yielded the strongest correlation (314 nm) and the concentrations from the laboratory. This led to a specific model which enabled transform the optical measurements into the B2M concentration values.
• the function in order to transform UV-absorbance (dimensionless) into the B2M concentration in mg/L, had the form:
• Table 4 summarises all results about the B2M concentrations as mean and standard deviation values (Mean +/- SD) from the standardised methods (Lab) and from the new method (UV).
• Table 4 Summary results about the concentration mean and standard deviation values (Mean +/- SD) from the standardised methods (Lab) and new method (UV), linear correlation coefficient (r) and the R-squared value (R ) between the uremic toxins concentration from the optical method and concentration measured at the laboratory, the accuracy (BIAS) and precision (SE) for the different methods to measure concentration of
• the removal of B2M from the optical measurements is estimated below to calculate the dialysis dose for B2M, being representative in its kinetic behavior of other MM and peptides of similar size.
• the dialysis dose for the B2M from blood, spKt/Vb_B2M and eKt/Vb_B2M can be calculated using the pre- and post- dialysis blood B2M concentrations (C 0 and C t ).
• the single pool volume Kt/V, spKt/Vb_B2M was calculated according to the formula proposed by Casino et al 2010 [1 1], as
• eKt/Vb _ B2M spKt/V p2m * T d /(T d + 11 ⁇ ) (4 where T d is the dialysis session length.
• the UV-absorbance value in the beginning, A 0 (9 min dialysate sample) and at the end of dialysis, A t were utilized at the wavelength which yielded the strongest correlation between B2M concentrations measured in the spent dialysate by the new method (by the UV absorbance) and at the laboratory (314 nm).
• the single pool volume Kt/V from the absorbance measurements, spKt/V a_B2M was calculated as
• Table 5 summarises all results about the dialysis dose for the B2M as eKt/V_B2M calculated using the pre- and post- dialysis blood B2M concentrations and the absorbance values from totally 20 HDF sessions.
• the linear correlation coefficient (r) and the R-squared value (R2) between the dialysis dose for B2M from the optical method and dialysis dose for B2M from the blood concentrations are given.
• the accuracy (BIAS) and precision (SE) for the optical method was calculated using dialysis dose for the B2M from blood as reference after bias correction.
• Table 5 Summary of dialysis dose as eKt/V_B2M, calculated by the TDC and the absorbance values on the tank dialysate sample (UV) , the linear correlation coefficient (r) and the R-squared value (R ) between the dialysis dose for B2M from the optical method and from the blood concentrations, the accuracy (BIAS) and precision (SE) for the optical method.
• the concentration of B2M from optical measurements is utilized below to calculate the total removed B2M, TR_B2M.
• Table 6 summarises all results about the dialysis dose for the B2M as the total removed B2M, TR_B2M, calculated using the B2M concentrations in the tank at the end of dialysis estimated at the laboratory (TDC), and by the UV-absorbance (UV) from totally 20 HDF sessions.
• the linear correlation coefficient (r) and the R-squared value (R2) between the dialysis dose for B2M from the optical method and dialysis dose for B2M from the blood concentrations are given.
• the accuracy (BIAS) and precision (SE) for the optical method was calculated using dialysis dose for the B2M from blood as reference after bias correction.
• Table 6 Summary of dialysis dose as TR B2M, calculated using using the B2M concentrations in the tank at the end of dialysis estimated at the laboratory (TDC) and by the UV-absorbance (UV), the linear correlation coefficient (r) and the R-squared value (R 2 ) between the dialysis dose for B2M from the optical method and from the blood concentrations, the accuracy (BIAS) and precision (SE) for the optical method.
• TDC UV-absorbance
• r linear correlation coefficient
• R 2 R-squared value
• WO2009071 102 Ivo Fridolin, Jana Jerotskaja, Kai Lauri and Merike Luman. Optical method and device for measuring concentrations of substances in biological fluids.

Landscapes

• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Investigating Or Analysing Biological Materials (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=44484872

Family Applications (1)

Country Status (2)

Families Citing this family (12)

Citations (1)

Family Cites Families (14)

• 2011
  • 2011-05-27 WO PCT/EE2011/000005 patent/WO2011147425A1/en active Application Filing
  • 2011-05-27 EP EP20110741089 patent/EP2577270A1/de not_active Withdrawn

Patent Citations (2)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events