WO2012038930A1 - Système de type « pratique de biologie délocalisée » pour mesurer la bilirubine plasmatique totale, notamment chez les nouveaux-nés - Google Patents

Système de type « pratique de biologie délocalisée » pour mesurer la bilirubine plasmatique totale, notamment chez les nouveaux-nés Download PDF

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Publication number
WO2012038930A1
WO2012038930A1 PCT/IB2011/054192 IB2011054192W WO2012038930A1 WO 2012038930 A1 WO2012038930 A1 WO 2012038930A1 IB 2011054192 W IB2011054192 W IB 2011054192W WO 2012038930 A1 WO2012038930 A1 WO 2012038930A1
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WIPO (PCT)
Prior art keywords
filter
membrane
plasma
bilirubin
irradiation
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PCT/IB2011/054192
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English (en)
Inventor
Richard Partridge Wennberg
Claudio Tiribelli
Giorgio Bergamo
Sandro Tognana
Antonio Maria Berto
Original Assignee
Fondazione Italiana Fegato-Onlus
Microlab Elettronica S.A.S. Di Bergamo Giorgio & C.
Innovation Factory S.R.L.
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Publication of WO2012038930A1 publication Critical patent/WO2012038930A1/fr

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    • 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
    • G01N21/314—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
    • G01N21/3151—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths using two sources of radiation of different wavelengths
    • 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
    • G01N21/27—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands using photo-electric detection ; circuits for computing concentration
    • G01N21/274—Calibration, base line adjustment, drift correction
    • 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
    • G01N21/55—Specular reflectivity
    • 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
    • G01N21/314—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
    • G01N2021/3181—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths using LEDs
    • 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
    • G01N2021/3185—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry typically monochromatic or band-limited
    • 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
    • G01N21/8483—Investigating reagent band
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/06—Illumination; Optics
    • G01N2201/062—LED's
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/06—Illumination; Optics
    • G01N2201/062—LED's
    • G01N2201/0623—Use of a reference LED
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/06—Illumination; Optics
    • G01N2201/062—LED's
    • G01N2201/0625—Modulated LED
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/12—Circuits of general importance; Signal processing
    • G01N2201/121—Correction signals
    • G01N2201/1211—Correction signals for temperature

Definitions

  • the invention relates to a system comprising a reading device having a reflectometer able to detect total plasma bilirubin from a plasma sample deprived of the respective corpuscular portion and a strip that is able to separate the plasma from a sample of whole blood.
  • the invention further relates to the method of determination of plasma bilirubin concentration by means of said system and to the use of the system comprising the reading device and the strip.
  • Transient jaundice due to unconjugated free bilirubin in the blood occurs in about 30% of neonates and is usually benign.
  • a bilirubin level of 25 mg/dL is regarded as the maximum safe limit in term-born neonates.
  • unconjugated bilirubin can cross . the blood-brain barrier, causing serious, permanent brain damage (principally kernicterus). It is therefore important to monitor the bilirubin level in jaundiced neonates to determine those neonates requiring suitable treatment for lowering the plasma bilirubin levels.
  • Current practice in the more developed countries is to monitor serum bilirubin levels before neonates are discharged.
  • This test is performed routinely by clinical laboratories using methods known by a person skilled in the art based on diazo reactions that generate coloured complexes measurable spectrophotometrically and requires from 0.5 to 1.0 ml of blood.
  • the bilirubin level can also be determined non-invasively by instrumental techniques, as no other yellow pigments are present in neonates.
  • a sufficiently accurate measurement can therefore be obtained by measuring the optical density of the plasma at 450-460 nm, which is the wavelength of the absorption peak of bilirubin.
  • An instrument (UB Analyzer, Arrows Inc; Osaka, Japan) measures both the total bilirubin and the free bilirubin, i.e. not bound to blood plasma proteins, but at present it is not available in the USA or Europe.
  • a portable instrument is in use, consisting of a transcutaneous reflectometer (BiliCheck®, Respironics Inc., Murrysville, PA).
  • the latter is an instrument offering the advantage that it is non-invasive and is sufficiently accurate for screening bilirubin levels up to about 15 mg/dL.
  • it also has many disadvantages, especially for use in developing countries where kernicterus is still one of the major health problems, or in medical studies.
  • a haemofluorometer of the "point of care" type is currently being developed for measuring bilirubin on whole blood.
  • the relation between blood bilirubin and plasma bilirubin depends on the binding affinity and the concentration of red blood cells. Clinical levels of correlation between blood and serum bilirubin have not yet been established.
  • Microfluidic systems for measuring plasma bilirubin are also under development, but the techniques currently available for these systems allow plasma to be separated from blood with limitation to haematocrit values below 45%.
  • the main problem in developing POC systems based on the use of plasma is that of obtaining a sufficient amount of plasma in the presence of high haematocrit levels (50-60% or more), which are common in neonates.
  • US02002/140940 relates to the analysis of blood samples in the very broad sense. With regard to bilirubin, this states that there are absorption peaks at certain wavelengths. In this connection, reference is made to a figure (3), which does not show the spectrum of bilirubin.
  • An optical probe is also described, whose reflectance is sent to a spectrometer, which separates and quantifies the various wavelengths.
  • This system has on the one hand the problem that a spectrometer must be available, and on the other hand the problem that the high levels of haemoglobin in whole blood, i.e. not separated into its components, obscure the contribution of reflectance from bilirubin, leading to unreliable results.
  • JP5924765 shows a blood/plasma separating system.
  • this system requires an enormous volume of blood to obtain a sufficient amount of plasma, which is transferred vertically onto a membrane for determination.
  • This solution is not satisfactory in the case of neonates, from whom it is difficult to take a large volume of blood.
  • the vertical transfer of the plasma makes the device particularly thick and hence inconvenient both for storage and for use.
  • One aim of the present invention is therefore to satisfy these needs, by overcoming the limitations of the transcutaneous reflectometer (e.g., BiliCheck) currently in use, and of those in development.
  • the transcutaneous reflectometer e.g., BiliCheck
  • the aim is thus to find a system for measuring total plasma bilirubin in the presence of high haematocrit levels with a high level of accuracy, that is easy to use and inexpensive.
  • a system comprising a reading device (or reader) of low cost having a reflectometer and a strip, which requires just 20-25 ⁇ of blood for executing measurement of total bilirubin and which has a reproducibility of 8% for amounts of total bilirubin greater than 30 mg/dL.
  • the present invention relates to a method of measuring the total bilirubin present in the plasma separated from a blood sample in a predetermined amount, the method comprising the following steps:
  • Blue light in fact incorporates substantially the whole absorption spectrum of the reflectance of bilirubin.
  • the plasma is not irradiated only with radiation corresponding to the absorption peak, nor is the reflectance separated into bands of different frequency.
  • Green light corresponds substantially to the whole absorption spectrum of haemoglobin and not only to its absorption peak. Higher levels of reflectance according to green light indicate greater contamination of the plasma and therefore a lower reliability of said bilirubin measurement.
  • the plasma sample can in fact be contaminated as a result of haemolysis of the red blood cells with release of haemoglobin into said plasma, which is why the bilirubin measurement is unreliable.
  • LEDs proves particularly economical relative to the known procedures that aim to irradiate exactly at the wavelength of the absorption peaks of the substances to be detected.
  • the method of the present invention also comprises preliminary separation of the plasma from the corpuscular portion of the blood.
  • Another aim of the present invention is to supply a strip for separating the plasma from a residual corpuscular portion of a predefined amount of blood, in such a way that this amount is greatly reduced and in order to perform it successfully on blood of neonates, i.e. having percentages of red blood cells between 50 and 70% of total blood.
  • the present invention further relates to a device for separating the plasma from a residual corpuscular portion of a predefined amount of blood consisting of a strip for separating the plasma from the corpuscular portion of a blood sample formed from a membrane and a filter that are partially overlapped, included in a support according to claim 9.
  • Another aim of the present invention is to supply a reader of devices for separating the plasma from a residual corpuscular portion of a predefined amount of blood, able to perform measurements of total bilirubin, in particular on neonates, which proves to be particularly economical and reliable.
  • the present invention also relates to a strip reader for separating the plasma from a residual corpuscular portion of a predefined amount of blood according to claim 14.
  • the system that has been developed for measuring total bilirubin will be described in detail below with reference to a preferred embodiment both of the reading device, or reflectometer, and of the disposable strips suitable for separating the plasma from a sample of whole blood taken from a subject whose bilirubinaemia is to be measured.
  • the dependent claims describe preferred embodiments of the invention, forming an integral part of the present description.
  • Fig. 1 shows the variation of reflectance in relation to the total bilirubin concentration
  • Figs. 2a and 2b show views, perpendicular to each other, of a first variant of strip
  • Figs. 3a and 3b show views, perpendicular to each other, of a second variant of strip
  • Fig. 3c shows a semifinished version of the variant shown in Figs. 3a and 3b;
  • Fig. 4 shows a part of the disposable strip reading device
  • Fig. 5 shows a logic diagram of a first variant of disposable strip reading device
  • Figs. 6 shows a logic diagram of a second variant of disposable strip reading device
  • Figs. 7 and 8 show flow charts of the operation of the devices according to Figs. 5 and 6.
  • the system for measuring plasma bilirubin is based on a method of measuring the total plasma bilirubin from a sample of whole blood comprising a step of depositing a sample of whole blood on a filter partially overlapping a membrane so that the filter holds back the corpuscular portion of the blood and the membrane receives the liquid portion (i.e. the plasma) without using any chemical reagents.
  • the method envisages measuring bilirubin by optical reflection by irradiating the membrane comprising the plasma with blue light radiation that contains substantially the whole absorption spectrum of bilirubin and the associated absorption peak that has a wavelength of about 470nm.
  • the measured reflection represents a proportional linear measure of the total bilirubin contained in the blood according to a negative logarithmic scale.
  • This curve is obtained by irradiating the plasma of blood samples, containing known levels of bilirubin, with blue light. This is equivalent to calibrating the measuring instrument, i.e. the strip reader, taking into account not only the absorption peaks, but the whole absorption spectrum.
  • a first advantage of this method is that it does not require a spectrometer, and it is not necessary to know the parameter known as "molar extinction", which is required for the operation of many spectrometers.
  • this method requires a very small amount of whole blood, in fact a prototype measuring system, which is also an object of the present invention, was able to perform reliable measurements with just 20-25 ⁇ of blood. Moreover, the complete absence of chemical reagents and extreme simplicity of use make the system easily portable and usable by anyone, mainly because no preliminary operation is required for separating the plasma from the corpuscular portion of the blood, which is separated automatically by the strip as conceived.
  • the method of measurement is performed by a plasma bilirubin measuring system comprising, referring to Figs. 2 to 4, a reader 1 having a reflectometer (Figs. 5, 6) and a separating device, i.e. a strip comprising a support, of the liquid plasma portion from a residual corpuscular portion of a predefined amount of blood 2, for simplicity called strip hereinafter (Figs. 2, 3).
  • the strip (or stick) 2 is described here with reference to Figs. 2a and 2b, and comprises a supporting band 21 housing a filter 22 and a membrane 23.
  • the purpose of the filter 22 is to separate the corpuscular portion of the blood from the plasma, which is transferred to a membrane 23 that absorbs it for the purpose of performing said optical measurement by reflection with the reader 1.
  • the supporting band 21 is in the form of a strip of material that is sufficiently rigid to be inserted in a reading opening of reader 1 .
  • the membrane 23 and the filter 22 are, with the sole exception of the overlap 24, stretched on the support 21. Therefore the strip is substantially flat and simple both to manipulate and to store.
  • the strip has a total length of about 3 centimetres and a width of about 3-7 mm, moreover the filter 22 has a length of 1 .5- 13 mm and the membrane 23 a length of 6 millimetres, with the overlap 24 of about 0.5-3 mm, comprising an overlap surface of 2-6 mm 2 , while the width of the membrane and of the filter is about 4 mm, so the membrane has a surface area of between 20 and 30 mm 2 with an optimum of 24 mm 2 .
  • the strip dimensions are not unimportant, bearing in mind that the time required for filtering the plasma and saturating the membrane increases with increase in haematocrit and with the filter dimensions. It is preferable for the membrane to be of nitrocellulose and to have characteristics similar to PrimaTM 85, which has capillarity between 70 and 105 (s/4 cm) and calibre 200 ( ⁇ ).
  • a filter for separating the plasma from the corpuscular portion of the blood can be selected from those known by a person skilled in the art and preferably made of a material consisting of a matrix of glass fibre and polyester that retains the blood cells and allows the plasma to pass through.
  • the supporting band 21 it is preferable, as shown in Figs. 2a and 2b, for the supporting band 21 to be slightly wider than the filter and the membrane, so as to have the lateral edges free of the supporting band and possibly of increased thickness, so that filter and membrane are contained within the outer surfaces of the strip.
  • Figs. 3a, 3b and 3c show a preferred variant of strip 80.
  • This comprises a containing support 99 that integrates a supporting band 81 substantially identical or similar to the supporting band 21 , on which a membrane 83 and a filter 82 are arranged, partially mutually overlapping so that they define an overlap 84. This is similar to strip 2.
  • the containing support 99 comprises a groove 85 in which said band 81 is inserted.
  • the same containing support 99 can define the supporting band 81.
  • this containing support 99 is obtained by folding a plastic or plastic-coated sheet, in the manner of origami.
  • the containing support 99 thus has a flat longitudinal shape, the groove extending parallel to this longitudinal form, preferably along the mid-line of the containing support 99.
  • a fin 86 is hinged to said containing support 99, with a rotation axis transverse to said longitudinal shape, on the face of the containing support 99 that comprises the groove 85 corresponding to the overlap 84 between membrane 83 and filter 82.
  • filter 82 and membrane 83 are housed in said groove 85 means that they are protected from the lateral edges of said groove, avoiding any contact with an internal part of the strip reader, which would lead to contamination thereof or soiling of its active parts.
  • This fin 86 is voluntarily not shown in Fig. 3b, for greater clarity of the figure.
  • This containing support can be made, advantageously, by folding sheets of paper, preferably plastic-coated, or plastic and similar materials.
  • the advantage of making the containing support 99 by folding a sheet of plastic- coated paper or a sheet of PVC and similar materials provides the undoubted advantage of not having to provide expensive moulds. This must also be evaluated in particular bearing in mind the presence of the fin 86 connected to the containing support 99 as described above.
  • the fin can be dimensioned and connected to the containing support 99 to produce a slight pressure on filter 82.
  • this pressure further facilitates passage of the plasma into the membrane.
  • this fin 86 defines a constricting and covering element of filter 82.
  • the semifinished article of the containing support 99 consists of a plastic-coated or plastic sheet punched to define a kind of cross with openings 97, made so that by folding the punch along the dotted edges, the filter and the membrane remain uncovered, always taking into account the position of the fin 86.
  • a particular object of the present invention is the strip 80 obtained by folding a plastic or plastic-coated sheet, as described here.
  • the reader 1 comprises processing means 1 1 and a reflectometer comprising a housing 10 which houses a photodiode 12 and, preferably, a first blue LED 13 with emission preferably centred on 470nm and a second green LED 18 centred on an emission wavelength of 570nm.
  • the photodiode 12 and the LEDs 13 and 18 are inserted in a housing 10 that has a groove 10' for receiving said strip 2.
  • Fig. 4 shows schematically an exploded view of the housing 10 (and 30).
  • This comprises a first lower part 101 which houses two pins with a sprung ball 102 and 102' and in which the groove 10' is made.
  • the housing comprises an upper part 103, comprising an optical collector 104, intended to be attached to said first lower part 101 so that the collector is aligned with the membrane of the strip.
  • said LEDs 13 and 18 and photodiode 12 are connected to a printed circuit 105.
  • the printed circuit is connected to the collector 104 for measuring the reflectance of the membrane.
  • the collector 104 can be made directly in the upper part 103 by milling and/or drilling.
  • the membrane has a width of about 4 mm, therefore the hole for measurement, through which the optical radiation passes, must have a slightly smaller diameter, with an optimum value of 3.2 mm. This is so as to be able to ensure, with a certain tolerance, that the membrane receives and emits simultaneously the light coming from the LEDs and photodiode that are located immediately above said membrane.
  • the collector 104 preferably metallic, comprises a through cavity, preferably countersunk, the reflective walls of which contribute to uniform distribution of the luminous intensity that impinges on the strip, compensating the misaligned position of the two LEDs relative to the photodiode and contributing to high repeatability of the measurements.
  • these three components 12, 13 and 18 are positioned perpendicularly to the longitudinal axis of the reader but this positioning is not obligatory.
  • the optical collector 104 collects the light from the membrane and sends it to the photodiode, which converts it into an electrical signal.
  • This signal is suitably amplified in the optical reader 1 , by a first amplifier 15 and a second amplifier 15' or third amplifier 15" depending on which of the blue or green LEDs is in operation (Fig. 5).
  • the amplified signal is then sent to an analogue/digital converter, preferably integrated in the microprocessor 1 1 , to be acquired and processed by the microprocessor.
  • the source of blue light is used for performing the bilirubin readings.
  • the optional source of green light is used for evaluating any contamination of the plasma by the haemoglobin contained in the red blood cells.
  • Green light is in fact preferentially absorbed by haemoglobin, which is red, which could interfere with the measurement of bilirubin.
  • the microprocessor 11 filters, with a low-pass filter, the signal received from the amplification section (15,15', 15") to remove some of the noise that accompanies the signal. Filtering of the signal is preferably executed by the firmware of the microprocessor 11 so as not to slow down the response time of the amplification section 15,15', 15" and of the optional offset correcting circuit 14.
  • Another preferred variant can comprise a single amplification stage with programmable gain controlled by the microprocessor 1 1 , for example a digi-pot or a programmable operational amplifier, rather than the cascade of two amplifiers as shown in Figs. 5 and 6.
  • the software filter currently used is preferably of the FIR type with 256 taps; however, various implementations such as MR or a different number of taps are equally valid. Any hardware filtering must be fast enough to take account of the reading times.
  • the luminous intensity of the blue LEDs and optionally of the green LED is, moreover, compensated directly by the microprocessor 1 1 or by the optional compensating circuit 14 connected to an input of said first amplifier 15 and to said microprocessor 11 as a function of the variations in ambient temperature and the variations in voltage of the batteries, etc., the reader shown in the present variant being supplied by a suitable battery power supply 88.
  • the firmware moreover, envisages displaying a bilirubin value, calculated according to the calibration curve stored in the microprocessor, and coinciding with that shown in Fig. 1 , on the display 16'.
  • the reader is provided with an alphanumeric display 16' that shows the result and supplies the operator with the messages necessary for correct use and operation of the reader, with which he can interact via a keypad 16.
  • the data visualized on the display can be sent to a personal computer via a USB port controlled by the microprocessor 11.
  • the LEDs are switched on for a very short time, preferably less than a second.
  • the reader comprises a microswitch or a further optical sensor (not shown) for detecting strip insertion.
  • the microprocessor 1 1 acquires the moment of strip insertion, from which a predefined time for stabilization of the measurements is counted.
  • the reader indicates a time-out error.
  • the signal generated by the photodiode is formed from two components:
  • ected while the term Vdiffused might cause a constant offset that limits the interval of useful signal.
  • said offset can be eliminated by means of said optional dedicated circuit 14a by the microprocessor 1 1 in order to report, in the optimum measurement interval, the useful signal produced by the photodiode 12.
  • the light of the LEDs it is preferable for the light of the LEDs to be suitably modulated with a frequency around KHz, in order to make the system insensitive to the ambient light. This necessitates the use of a software or hardware demodulator to regain the correct measurement of the reflected light after removing the constant contribution of the ambient light.
  • Switching-on of the LEDs is controlled by a suitable circuit 17 controlled by the microprocessor 11.
  • a preferred calibration procedure envisages the following steps:
  • the microprocessor shows the instructions on the display that the user must carry out and in particular requests sequential insertion of a predefined strip number with colour corresponding to known, stable concentration, for example made with suitable paints or by strip impregnated with coloured liquids that simulate a known concentration,
  • the firmware calculates the coefficients of logarithmic regression in order to correlate the measured reflectance with the bilirubin level.
  • the reflectometer comprises a housing 30, entirely similar to Fig. 5 and indicated there as 10 and shown in Fig. 4, comprising said diode with blue light 33 and a photodiode 32 inserted near a groove 30'.
  • An LED 38 with green light is optional. Switching-on of the LEDs is controlled by a suitable circuit 37 connected to a USB interface 31 . The following are connected to the same USB interface 31
  • an analogue/digital converter 36 able to convert the signals generated by the amplification section 35, 35' and 35" of the signals generated by the LEDs and
  • the present variant is particularly advantageous in countries and locations where a computer is available, and the electric power supply for the latter, while the previous variant is more advantageous in poor countries, since the device comprises per se the necessary components for performing a bilirubin measurement.
  • the system can measure plasma bilirubin with an accuracy of ⁇ 5% at bilirubin concentrations in the range 3-30 mg/dL (approx. 50-500 ⁇ /L) at haematocrit level up to 60%. Even at high haematocrit levels (up to 75%), 20-25 ⁇ of blood is sufficient for measuring plasma bilirubin.
  • the accuracy of a system as described was determined using both haematocrit (hct 45%, bilirubin 9.2 mg/dL) and plasma (bilirubin 5 mg/dL, 22 mg/dL).
  • the coefficient of variation (CV) calculated on 9 and 2 samples respectively was less than 5% for both.
  • the reproducibility and accuracy of the system was tested on the blood of adult subjects containing high (55-60%) and low haematocrit concentrations (40-45%) and containing bilirubin levels of 25-30 mg/dL and 8-10 mg/dL.
  • the reading time can vary from 12 seconds with haematocrit concentration of 25% up to 150 seconds for haematocrit concentrations of 65%, depositing 25 ⁇ of blood on a filter of about 50-54 mm 2 or depositing 20 ⁇ of blood on a filter of about 42-46 mm 2 .
  • the contamination of the blood is limited when the haematocrit exceeds a concentration of 60-62%.
  • the filter dimensions must be greater than 40 mm 2 .
  • the method comprises the following steps:
  • step 41 checks whether a calibration of the device is stored in memory
  • step 42 checks that the voltage level supplied from the power supply 88, 98 is adequate, if the voltage level is not adequate it stops, step 53, otherwise it goes to the next step - step 43, wait for insertion of a strip in the reader (1 , 1 '),
  • step 45 waiting until the reading has stabilized with optional setting of a time-out, for example of 350 s,
  • step 46 carrying out a predefined number of readings, preferably 256,
  • step 47 switching-off the blue LED and optional reading by switching-on the green LED 13, 38 with optional loading of the value of offset relative to the green LED memorized during calibration of the reader and subtraction, at the analogue stage, of said optional value of offset from the output signal of the photodiode 12, 32,
  • this stabilization is necessary to stabilize the electronic circuitry defining the reader, to stabilize the conversions of the analogue/digital signal in relation to optional elimination of the offset and to obtain a stable light from the LEDs, which must reach an optimum operating temperature,
  • step 49 performing a predefined number of readings, preferably 256.
  • step 50 calculation of the threshold of the green from the measurement of the blue by means of a conversion table that links at least one reflectance value of bilirubin with at least one reflectance value of haemoglobin resulting from lysis of the red blood cells,
  • step 51 verification that the measurement made with the green LED is below a predefined threshold
  • step 51 yes step 52, cancellation of the measurements and sending of a warning message
  • step 42 checking battery levels, etc. - if the measurement carried out with the green LED is above said predefined threshold (step 51 No), step 56, calculation of the bilirubin concentration by means of the coefficients of the calibration curve stored in memory,
  • step 57 presentation of the results on display 16'.
  • any value of offset from the reflectance measurement is effected at the hardware level, i.e. in the analogue domain and not digital because otherwise the amplifier stages might saturate with unforeseeable results.
  • An optimum number of readings is found to be 256 because 256 is equivalent to 2 ⁇ 8, which is the maximum number of values that can be expressed by one byte (8 bits). Using this value, the routine for calculating the mean value becomes very quick and efficient.
  • the 256 readings are necessary for filling the delay line of the FIR filter (namely 256 taps) and to be able to calculate at least one output. Moreover, filter design is simplified since division by 256 coincides with shift of 8 bits to the right.
  • variable sum is an integer without sign at 32bit
  • Implementation of this method of signal processing makes it possible to obtain higher resolution or use 10-bit or 8-bit A/D converters, reducing the costs of the reader, but maintaining a final accuracy equivalent to 12-bit and a pass band equally limited, for reducing noise.
  • Fig. 8 shows a flow chart relating to a method of calibration of the reader performed at step 54 of the method of Fig. 7.
  • This method comprises the following steps:
  • step 70 up to step N+70 carrying out a sequence of readings of a coloured membrane by means of a known coloration determining a reflectance value relating to a known bilirubin titre
  • step 72 execution of a logarithmic regression on said sequence of readings and calculation of the coefficients of the logarithmic function applied in the calculation of the bilirubin concentration described at step 56,
  • Fig. 7, top right, also shows a flow chart of the method of checking that the voltage level supplied by the power supply 88, 98 is adequate.
  • the present invention can advantageously be implemented by means of a computer program that comprises coding means for performing one or more steps of the method, when this program is carried out on a computer. Therefore it is intended that the scope of protection should extend to said computer program and moreover to computer-readable means that comprise a recorded message, said computer- readable means comprising program coding means for carrying out one or more steps of the method, when said program is carried out on a computer.

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Abstract

Cette invention concerne un dispositif et un procédé pour déterminer le taux de bilirubine plasmatique, notamment, chez les nouveaux-nés. Le système pour mesurer la bilirubine plasmatique comprend un instrument pourvu d'un réflectomètre, capable de détecter la bilirubine plasmatique dans un échantillon de sang dont la partie corpusculaire respective a été séparée sur une membrane conçue à cet effet et une bandelette ou un bâtonnet réactif comprenant un filtre et la membrane. Le système constitué de l'instrument et de la bandelette réactive peut mesurer la bilirubine plasmatique à une précision de +/- 5 % et des concentrations de bilirubine dans la plage de 3 à 30 mg/dL (environ 50 à 500 µMol/L) à un taux d'hématocrite jusqu'à 60 % sur des échantillons de sang d'à peine 20 à 25 µl.
PCT/IB2011/054192 2010-09-23 2011-09-23 Système de type « pratique de biologie délocalisée » pour mesurer la bilirubine plasmatique totale, notamment chez les nouveaux-nés WO2012038930A1 (fr)

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ITMI2010A001730 2010-09-23
IT001730A ITMI20101730A1 (it) 2010-09-23 2010-09-23 Sistema di tipo "point of care" di misura della bilirubina totale nel plasma, in particolare di neonati

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT201600094056A1 (it) * 2016-09-20 2018-03-20 Bilimetrix S R L Metodo di taratura per un dispositivo di misura della bilirubina
IT201600094078A1 (it) * 2016-09-20 2018-03-20 Bilimetrix S R L Portacampione per il contenimento di un campione ematico, dispositivo di misurazione per ricevere il portacampione e relativo sistema di misurazione
JP2018518242A (ja) * 2015-05-14 2018-07-12 ゼネラル・エレクトリック・カンパニイ 血漿の分離および回収装置
EP3470839A1 (fr) * 2017-10-12 2019-04-17 Koninklijke Philips N.V. Système et procédé de mesure de la bilirubine et de l'hémoglobine
WO2019089768A1 (fr) * 2017-11-01 2019-05-09 William Marsh Rice University Dispositif à faible ressource et système de mesure des taux de bilirubine
JP2020024219A (ja) * 2013-11-28 2020-02-13 エフ．ホフマン−ラ ロシュ アーゲーＦ． Ｈｏｆｆｍａｎｎ−Ｌａ Ｒｏｃｈｅ Ａｋｔｉｅｎｇｅｓｅｌｌｓｃｈａｆｔ 体液中の分析物の濃度を決定する方法及び装置
WO2021195120A1 (fr) * 2020-03-24 2021-09-30 In Diagnostics, Inc. Spectrophotomètre clinique pour chimie générale, dosage immunologique et détection d'acide nucléique

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3569721A (en) * 1969-01-13 1971-03-09 American Optical Corp Measuring bilirubin in blood using light at two wavelengths
JPS59214765A (ja) 1983-05-20 1984-12-04 Mochida Pharmaceut Co Ltd 血漿分離装置とその使用方法
WO1987002267A1 (fr) * 1985-10-18 1987-04-23 Chem-Elec, Inc. Bande de test pour serum sanguin
US5558834A (en) * 1991-10-03 1996-09-24 Bayer Corporation Device and method of seperating and assaying whole blood
WO1997015229A1 (fr) * 1995-10-23 1997-05-01 Cytometrics, Inc. Procede et appareil d'analyse par imagerie reflechie
WO2000062060A2 (fr) * 1999-04-08 2000-10-19 Chimera Research And Chemical Inc. Methode utilisant un appareil hybride a ecoulement lateral pour detecter des melanges a analyser dans de l'urine
US20020140940A1 (en) 2001-02-28 2002-10-03 Bambot Shabbir B. System and method for measurement and analysis of a sample by absorption spectrophotometry
US20040241752A1 (en) * 1998-02-03 2004-12-02 Anderson Emory V. Point of care diagnostic systems

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3569721A (en) * 1969-01-13 1971-03-09 American Optical Corp Measuring bilirubin in blood using light at two wavelengths
JPS59214765A (ja) 1983-05-20 1984-12-04 Mochida Pharmaceut Co Ltd 血漿分離装置とその使用方法
WO1987002267A1 (fr) * 1985-10-18 1987-04-23 Chem-Elec, Inc. Bande de test pour serum sanguin
US5558834A (en) * 1991-10-03 1996-09-24 Bayer Corporation Device and method of seperating and assaying whole blood
WO1997015229A1 (fr) * 1995-10-23 1997-05-01 Cytometrics, Inc. Procede et appareil d'analyse par imagerie reflechie
US20040241752A1 (en) * 1998-02-03 2004-12-02 Anderson Emory V. Point of care diagnostic systems
WO2000062060A2 (fr) * 1999-04-08 2000-10-19 Chimera Research And Chemical Inc. Methode utilisant un appareil hybride a ecoulement lateral pour detecter des melanges a analyser dans de l'urine
US20020140940A1 (en) 2001-02-28 2002-10-03 Bambot Shabbir B. System and method for measurement and analysis of a sample by absorption spectrophotometry

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Section Ch Week 198503, Derwent World Patents Index; Class A96, AN 1985-016665, XP002638022 *

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2020024219A (ja) * 2013-11-28 2020-02-13 エフ．ホフマン−ラ ロシュ アーゲーＦ． Ｈｏｆｆｍａｎｎ−Ｌａ Ｒｏｃｈｅ Ａｋｔｉｅｎｇｅｓｅｌｌｓｃｈａｆｔ 体液中の分析物の濃度を決定する方法及び装置
JP2018518242A (ja) * 2015-05-14 2018-07-12 ゼネラル・エレクトリック・カンパニイ 血漿の分離および回収装置
IT201600094056A1 (it) * 2016-09-20 2018-03-20 Bilimetrix S R L Metodo di taratura per un dispositivo di misura della bilirubina
IT201600094078A1 (it) * 2016-09-20 2018-03-20 Bilimetrix S R L Portacampione per il contenimento di un campione ematico, dispositivo di misurazione per ricevere il portacampione e relativo sistema di misurazione
WO2018055510A1 (fr) * 2016-09-20 2018-03-29 Bilimetrix S.R.L. Procédé d'étalonnage d'un dispositif servant à mesurer la concentration d'un composé biologique
CN109844497A (zh) * 2016-09-20 2019-06-04 比利蜜特有限责任公司 用于校准用于测量生物化合物浓度的设备的方法
CN109844497B (zh) * 2016-09-20 2021-10-26 比利蜜特有限责任公司 用于校准用于测量生物化合物浓度的设备的方法
US11513062B2 (en) 2016-09-20 2022-11-29 Bilimetrix S.R.L. Method for calibrating a device for measuring the concentration of a biological compound
EP3470839A1 (fr) * 2017-10-12 2019-04-17 Koninklijke Philips N.V. Système et procédé de mesure de la bilirubine et de l'hémoglobine
WO2019089768A1 (fr) * 2017-11-01 2019-05-09 William Marsh Rice University Dispositif à faible ressource et système de mesure des taux de bilirubine
WO2021195120A1 (fr) * 2020-03-24 2021-09-30 In Diagnostics, Inc. Spectrophotomètre clinique pour chimie générale, dosage immunologique et détection d'acide nucléique

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