NL2030042B1 - A method and sensor system for characterizing in vivo the concentration of a compound in amniotic fluid - Google Patents
A method and sensor system for characterizing in vivo the concentration of a compound in amniotic fluid Download PDFInfo
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- A—HUMAN NECESSITIES
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- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
- A61B5/0075—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
- A61B5/0082—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence adapted for particular medical purposes
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- A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
- A61B5/14546—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue for measuring analytes not otherwise provided for, e.g. ions, cytochromes
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- G01N2333/435—Assays involving biological materials from specific organisms or of a specific nature from animals; from humans
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- G01N2333/62—Insulins
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- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
- G01N33/66—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving blood sugars, e.g. galactose
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Abstract
The present invention relates to a method and sensor system for characterizing in vivo and in situ the concentration of a compound in amniotic fluid through spectroscopic measurements, such as the compound lactate, glucose, insulin and lecithin/sphingomyelin.
Description
A method and sensor system for characterizing in vivo the concentration of a compound in amniotic fluid
[0001] The invention relates to the field of medicine, to the in vivo determination of the concentration of a compound through spectroscopic measurements. The invention further relates to the in vivo determination through spectroscopic measurements of a compound in amniotic fluid, such as the compound lactate, a parameter indicative of the level of oxygenation of a foetus.
INTRODUCTION
[0002] The introduction of the invention includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] In the past few decades the determination of concentrations of compounds such as glucose, lactate, insulin (which may be a marker of (gestational) diabetes), and lecithin/sphingomyelin ratios in amniotic fluid as obtained through amniocentesis from infrared spectra has been established as an accepted method of quantification of said compounds.
[0004] Concentrations of compounds such as glucose, lactate, and lecithin/sphingomyelin ratios are known to be indicative of and/or can predict preterm infection, foetal distress, and foetal lung maturity.
[0005] In particular, the concentration of lactate during pregnancy and during the progress of labour is indicative of and/or can predict foetal oxygenation and thus overall foetal well-being, and is an important factor for the survival rate of new-born infants. (K.Z. Liu, H.H. Mantsch, “Simultaneous quantification from infrared spectra of glucose concentrations, lactate concentrations, and lecithin/sphingomyelin ratios in amniotic fluid”, Am J Obstet Gynecol 180, 697 1999).
[00086] Further, protein composition of amniotic fluid, as established by proteomics analysis of amniotic fluid obtained through amniocentesis, is thought to be associated to birth timing. Early changes in the amniotic fluid proteome can be associated with spontaneous preterm delivery. In particular neutrophil gelatinase-
associated lipocalin and Plasminogen activator inhibitor 1 appear to be potential biomarkers of spontaneous preterm delivery and gestational durations, although the findings could not be replicated (M. Hallingström et al. Mid-trimester amniotic fluid proteome’s association with spontaneous preterm delivery and gestational duration
PLoS ONE 15(5): e0232553 2020).
[0007] Some clinical practices determine the lactate concentration through a so-called foetal scalp micro blood examination, for which the foetal membranes need to be penetrated. Hence, this can only be done during labour and delivery, is a non- continuous measurement and can only be done a few times for an individual foetus.
[0008] Foetal oxygenation is further estimated through cardiotocography (CTG), which may be indicative, but is not clinically decisive.
[0009] Various terms relating to the methods, systems, uses and other aspects of the present invention are used throughout the specification and claims. Such terms are to be given their ordinary meaning in the art to which the invention pertains, unless otherwise indicated. Other specifically defined terms are to be construed in a manner consistent with the definition provided herein. Although any methods and materials similar or equivalent to those described herein can be used in the practice for testing of the present invention, the preferred materials and methods are described herein.
[0010] For purposes of the present invention, the following terms are defined below.
[0011] As used herein, the singular form terms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to “a signal” includes a series of consecutive signals.
[0012] As used herein, “about” and “approximately”, when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass variations of £20% or £10%, more preferably £5%, even more preferably 11%, and still more preferably +0.1% from the specified value, as such variations are appropriate to perform the disclosed invention.
[0013] As used herein, “and/or” refers to a situation wherein one or more of the stated cases may occur, alone or in combination with at least one of the stated cases, up to with all of the stated cases.
[0014] As used herein, “at least" a particular value means that particular value or more. For example, "at least 2" is understood to be the same as "2 or more" i.e., 2, 3,4,5 6,7,8, 9, 10, 11, 12, 13, 14, 15, etc. As used herein, the term "at most’ a particular value means that particular value or less. For example, "at most 5" is understood to be the same as "5 or less" i.e, 5, 4, 3,-10, -11, etc.
[0015] As used herein, “comprising” or “to comprise” is construed as being inclusive and open ended, and not exclusive. Specifically, the term and variations thereof mean the specified features, steps or components are included. These terms are not to be interpreted to exclude the presence of other features, steps or components. It also encompasses the more limiting “to consist of”.
[0016] As used herein, “conventional techniques” or “methods known to the skilled person” refer to a situation wherein the methods of carrying out the conventional techniques used in methods of the invention will be evident to the skilled worker. The practice of conventional techniques in spectroscopy, proteomics, genomics, molecular biology, biochemistry, medical treatment, diagnosis, pharmacology, gynaecology and related fields are well-known to those of skill in the art, and are discussed in various handbooks and literature references.
[0017] As used herein, “spectroscopy” refers to the study of the interaction between light and matter, e.g. the reflection, absorption and/or emission of electromagnetic radiation by matter, as related to the dependence of these processes on the wavelength of the radiation. Spectroscopic techniques can be extremely sensitive. For instance, trace amounts of pollutants or contaminants are often detected most effectively by spectroscopic techniques. Spectroscopy can be performed within a sizable fraction of the electromagnetic spectrum, including infrared.
[0018] As used herein, “infrared spectroscopy” refers to the measurement of the interaction of infrared electromagnetic radiation with matter by emission, absorption, or reflection. It is used to study and identify chemical substances or functional groups in solid, liquid, or gaseous forms. In the present invention the source of electromagnetic radiation is configured for emitting in the range of wavelengths between 400 nm and 1 cm, preferably between 780 nm and 1mm, and such that it is harmless to the body and the unborn foetus.
[0019] As used herein, “amniocentesis” refers to a prenatal testing procedure usually performed during the second or third trimester of pregnancy, comprising the removal of a small amount of amniotic fluid from the sac surrounding the foetus. The fluid sample will then be tested in a laboratory.
[0020] The amniotic fluid tested in the abovementioned prior art were obtained by amniocentesis. The disadvantage of in vitro probing of an amniotic fluid sample is that to obtain the sample, the amniotic sac needs to be pierced with a needle which constitutes a risk of infection, a risk of rupture of foetal membranes and of miscarriage.
[0021] In light of the foregoing, new in vivo methods and measuring systems for the quantification of biomarkers in amniotic fluid, which are non-invasive, are desirable. In particular there is a clear need in the art for reliable, save, single and repetitive measurement in vivo of compounds in amniotic fluid wherein the methods and measuring systems meet nowadays standards.
[0022] It has now been found by the present inventors that biomarkers in the amniotic fluid can be continuously and directly probed and monitored non-invasively in vivo and in situ. The present invention is hence related to a sensing system placed inside the uterine cavity against the foetal membrane using electromagnetic radiation allowing quantification of biomarkers such as lactate in the amniotic fluid. The advantage of probing an amniotic fluid sample using infrared spectroscopy is that the infrared radiation can be used for characterization in a non-invasive way.
[0023] Accordingly, the technical problem underlying the present invention can be seen in the provision of aforementioned methods and systems for complying with any of the aforementioned needs. The technical problem is solved by the embodiments characterized in the claims and herein below.
[0023] In a first aspect, the present invention relates to a method of characterizing in vivo the concentration of a compound in amniotic fluid, the method comprising; - emitting, by an emitter system for emitting electromagnetic radiation, a first emitted signal being a first electromagnetic radiation emitted towards the amniotic fluid such that the radiation interacts with the amniotic fluid;
- detecting, by a detector system for detecting electromagnetic radiation, a response signal being the detected electromagnetic radiation, having interacted with the amniotic fluid; - determining, by a processing system communicatively coupled to the emitter 5 system and the detector system, at least one concentration of at least one component of the amniotic fluid based on the response signal.
[0024] In one embodiment, the emitted signal is compared with the response signal and the comparison includes a determination of optical material properties, such as indices of refraction and absorption coefficients.
[0025] In another embodiment, the emitted signal and/or the comparison of emitted and response signal takes into account spectroscopic properties of the amniotic and chorionic membrane and/or spectroscopic properties of a reference amniotic fluid.
[0026] In yet another embodiment the concentration of at least one component of the amniotic fluid is obtained by optimizing model parameters of a physical and or data-driven model, where the model parameters are indicative of the concentration of the at least one component.
[0027] In yet another embodiment the component is chosen from the group lactate, glucose, insulin and lecithin/sphingomyelin.
[0028] In yet another embodiment the sensor system is positioned between the lower uterine segment and the chorionic membrane, intra-cervically or vaginally.
[0029] In yet another embodiment the sensor system as a whole or the emitter system and the detector system are positioned between the lower uterine segment and the chorionic membrane, intra-cervically or vaginally.
[0030] In yet another embodiment the sensor system as a whole or the emitter and detector system may be positioned between the lower uterine segment and the chorionic membrane, intra-cervically or vaginally.
[0031] In a preferred embodiment the method of characterizing in vivo the concentration of a compound in amniotic fluid is being carried out by a sensor system, comprising (i) an emitter system for emitting electromagnetic radiation, (ii) a detector system for detecting electromagnetic radiation and (iii) a processing system communicatively coupled to the emitter system and the detector system, the method comprising;
- Emitting, by the emitter system, a first emitted signal being a first electromagnetic radiation emitted towards the amniotic fluid such that the radiation interacts with the amniotic fluid; - Detecting by a detector system a response signal being the detected electromagnetic radiation, having interacted with the amniotic fluid; - Determining by the processing system at least one concentration of at least one component of the amniotic fluid based on the response signal.
[0032] The invention thus relates to a method and system to directly probe the concentration of certain compounds, such as lactate, in the amniotic fluid. The method and system are non-invasive, don’t induce the risk of rupture of the foetal membranes nor ask for direct contact with the foetus. The method and system allows single, repetitive and continuous measurements of the concentration of particular compounds, such as lactate. Lactate can be probed directly, instead of a related biomarker from which the lactate concentration must be derived. The method and system uses electromagnetic radiation to quantify the aforementioned compounds in the amniotic fluid. The electromagnetic radiation is chosen such that the reflected radiation pattern contains information about the concentration of said compounds in the amniotic fluid.
[0033] In a second aspect, the present invention relates to a sensor system, comprising (i) an emitter system for emitting electromagnetic radiation, (ii) a detector system for detecting electromagnetic radiation and (iii) a processing system communicatively coupled to the emitter system and the detector system, used for the characterization in vivo of the concentration of a compound in amniotic fluid.
[0034] In one embodiment the processing system is connected to the emitter and detector system via a communication means such that the processing system can be placed outside of the body.
[0035] In another embodiment the source of electromagnetic radiation, is connected to an optical cable such that the source of electromagnetic radiation can be placed outside of the body.
[00386] In yet another embodiment said the source of electromagnetic radiation is configured for emitting in the range of wavelengths between 400 nm and 1 cm, preferably between 780 nm and 1mm.
[0037] Thus, in a preferred embodiment the present invention relates to a method of characterizing in vivo the concentration of a compound in amniotic fluid, the method being carried out by a sensor system, comprising (i) an emitter system for emitting electromagnetic radiation, (ii) a detector system for detecting electromagnetic radiation and (iii) a processing system communicatively coupled to the emitter system and the detector system, the method comprising; - Emitting, by the emitter system, a first emitted signal being a first electromagnetic radiation towards the amniotic fluid such that the radiation interacts with the amniotic fluid; - Detecting by a detector system a response signal being the detected electromagnetic radiation, having interacted with the amniotic fluid; - Determining by the processing system at least one concentration of at least one component of the amniotic fluid based on the response signal, wherein said emitted signal is compared with said response signal and said comparison includes a determination of absorbed radiation, and said emitted signal and/or said comparison of emitted and response signal takes into account spectroscopic properties of the amniotic and chorionic membrane and/or spectroscopic properties of a reference amniotic fluid, the concentration of at least one component of the amniotic fluid is obtained by optimizing model parameters of a physical and or data-driven model, where the model parameters are indicative of the concentration of the at least one component, and said component is lactate, the sensor system as a whole or the emitter system and the detector system are positioned in the uterine cavity, between the lower uterine segment and the foetal membrane to directly probe the concentration of certain compounds, such as lactate, in the amniotic fluid, and said source of electromagnetic radiation is configured for emitting in the range of wavelengths between 400 nm and 1 cm, preferably between 780 nm and 1mm.
[0038] The sensor system is a small probe emitting and receiving electromagnetic radiation (ranging between 400 nm and 1 cm), which may be inserted in the uterine cavity. The probe can be used for a single measurement, or for durative measurements. Cables, such as optical fibers may be connected to the probe. In case of durative measurements, the probe is a self-powered capsule-like sensing device.
[0039] The sensor system may be placed between the lower uterine segment and the chorionic membrane, intra-cervically or vaginally. It may radiate a plurality of electromagnetic waves that partially reflect onto and transmit through the tissues separating the sensor system and the amniotic fluid, before it interacts with the amniotic fluid. The interaction is based on a unique vibrational response of the probed compound inside its liquid environment to the emitted radiation pattern.
[0040] The radiation pattern may be chosen such that it transmits through the material between the sensor system and the amniotic fluid, as to avoid absorptions form e.g. fat or water. The interacted portion of the radiation eventually is reflected back to the sensor system and detected. The ratio of the outgoing and incoming radiation contains the information about the stratified system of connective tissue, chorionic and amnionic membranes and the amniotic liquid. The concentration of the probed compound, such as lactate, may then be determined from integration of the absorption pattern related to the aforementioned unique vibrational response of the probed compound to the emitted radiation pattern.
[0041] Thus, in a preferred embodiment, the sensor system is a small self- powered capsule-like sensing device emitting and receiving electromagnetic radiation (ranging between 1 cm and 400 nm), which is inserted in the uterine cavity, used for durative measurements, placed inside the uterine cavity, between the lower uterine segment and the chorionic membrane, configured to radiate a plurality of electromagnetic waves that partially reflect onto and transmit through the tissues separating the sensor system and the amniotic fluid, before it interacts with the amniotic fluid, based on a unique vibrational response of the probed compound, preferably lactate, inside its liquid environment to the emitted radiation pattern, chosen such that it transmits through the material between the sensor system and the amniotic fluid, as to avoid absorptions form e.g. fat or water, the interacted portion of the radiation eventually is reflected back to the sensor system and detected, the ratio of the outgoing and incoming radiation contains the information about the stratified system of connective tissue, chorionic and amnionic membranes and the amniotic liquid, and the concentration of the probed compound, such as lactate, is then determined from integration of the absorption pattern related to the aforementioned unique vibrational response of the probed compound to the emitted radiation pattern.
[0042] Signal processing techniques, including machine learning algorithms, may be used to enhance the response sensitivity.
[0043] Various aspects and features are herein described. Details are set forth to provide a thorough understanding of the present disclosure. It will be apparent, however, to those having ordinary skilled in the art that the disclosed spectroscopic methods may be practiced or performed without some or all of these specific details and the disclosed sensor system may comprise some or all of these specific details.
Simulating optical lactate detection in amniotic fluid
[0044] To allow for and perform simulation of optical lactate detection in amniotic fluid the following steps of increasing complexity are carried out: - Spectroscopic measurement at infrared frequencies of first lactate powder, then dissolved lactate in water or commercially available artificial amniotic fluid. - Determination of the optical properties of the tissue separating the foreseen sensor head and the amniotic fluid, such as connective tissue, chorionic and amnionic membranes and amniotic liquid. - Simulation of the propagation of electromagnetic radiation through the above mentioned multilayer stack and subsequent interaction with the dissolved lactate. - Estimation of the sensitivity of the sensor using the above simulation and typical concentrations during pregnancy of the lactate concentration.
Signal processing method
[0045] The signal processing method comprises physical models, describing the interaction of electromagnetic radiation with stratified systems (Van Mechelen
J.L.M., Kuzmenko A.B., Merbold H. Stratified dispersive model for material characterization using terahertz time-domain spectroscopy, Optics letters, July 1, 2014, Vol. 39, No. 13) in a biological system comprising connective tissue, chorionic and amnionic membranes and amniotic liquid. To account for biological systems being much more complex than physical models, hybrid signal processing schemes are used to determine the degree of lactate. These schemes consist of a physical model-driven analyses complemented with Al principles based on deep-learning. In this framework, the physical model acts as a prior for the data-driven model.
Based on the above simulation, a device in accordance with the inventions is configured.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040267139A1 (en) * | 2001-11-09 | 2004-12-30 | Naohiro Kanayama | Instrument for measuring intrauterine oxygen metabolism using optical technique |
| US20060247536A1 (en) * | 2003-08-21 | 2006-11-02 | Mcgill University | Method and apparatus for analyzing amniotic fluid |
| US20100324391A1 (en) * | 2007-10-16 | 2010-12-23 | Genady Kostenich | Device and Method for Identification of Meconium in Amniotic Fluid |
| WO2013165888A2 (en) * | 2012-04-30 | 2013-11-07 | Mayo Foundation For Medical Education And Research | Spectrometric systems and methods for improved focus localization of time-and space-varying measurements |
-
2021
- 2021-12-06 NL NL2030042A patent/NL2030042B1/en active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040267139A1 (en) * | 2001-11-09 | 2004-12-30 | Naohiro Kanayama | Instrument for measuring intrauterine oxygen metabolism using optical technique |
| US20060247536A1 (en) * | 2003-08-21 | 2006-11-02 | Mcgill University | Method and apparatus for analyzing amniotic fluid |
| US20100324391A1 (en) * | 2007-10-16 | 2010-12-23 | Genady Kostenich | Device and Method for Identification of Meconium in Amniotic Fluid |
| WO2013165888A2 (en) * | 2012-04-30 | 2013-11-07 | Mayo Foundation For Medical Education And Research | Spectrometric systems and methods for improved focus localization of time-and space-varying measurements |
Non-Patent Citations (2)
| Title |
|---|
| M. HALLINGSTROM ET AL.: "Mid-trimester amniotic fluid proteome's association with spontaneous preterm delivery and gestational duration", PLOS ONE, vol. 15, no. 5, 2020, pages e0232553 |
| VAN MECHELEN J.L.M.KUZMENKO A.B.MERBOLD H: "Stratified dispersive model for material characterization using terahertz time-domain spectroscopy", OPTICS LETTERS, vol. 39, no. 13, 1 July 2014 (2014-07-01) |
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