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WO2009031119A1 - Surveillance du degré d'hydratation du corps humain - Google Patents

Surveillance du degré d'hydratation du corps humain Download PDF

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Publication number
WO2009031119A1
WO2009031119A1 PCT/IB2008/053589 IB2008053589W WO2009031119A1 WO 2009031119 A1 WO2009031119 A1 WO 2009031119A1 IB 2008053589 W IB2008053589 W IB 2008053589W WO 2009031119 A1 WO2009031119 A1 WO 2009031119A1
Authority
WO
WIPO (PCT)
Prior art keywords
blood vessel
blood
occlusion
light
acoustical signal
Prior art date
Application number
PCT/IB2008/053589
Other languages
English (en)
Inventor
Yan Shi
Ladislav Jankovic
Original Assignee
Koninklijke Philips Electronics N.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2009031119A1 publication Critical patent/WO2009031119A1/fr

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Classifications

    • 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
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/0093—Detecting, measuring or recording by applying one single type of energy and measuring its conversion into another type of energy
    • A61B5/0095—Detecting, measuring or recording by applying one single type of energy and measuring its conversion into another type of energy by applying light and detecting acoustic waves, i.e. photoacoustic measurements
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/48—Other medical applications
    • A61B5/4869—Determining body composition
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/08—Clinical applications
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2560/00—Constructional details of operational features of apparatus; Accessories for medical measuring apparatus
    • A61B2560/02—Operational features
    • A61B2560/0242—Operational features adapted to measure environmental factors, e.g. temperature, pollution
    • A61B2560/0247—Operational features adapted to measure environmental factors, e.g. temperature, pollution for compensation or correction of the measured physiological value
    • A61B2560/0252—Operational features adapted to measure environmental factors, e.g. temperature, pollution for compensation or correction of the measured physiological value using ambient temperature
    • 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
    • G01N21/1702—Systems in which incident light is modified in accordance with the properties of the material investigated with opto-acoustic detection, e.g. for gases or analysing solids

Definitions

  • the invention relates to the field of monitoring the degree of hydration of the human body based on measuring the time for refilling an occluded blood vessel with blood, especially by measuring vein refilling time (VRT) and/or capillary refilling time (CRT).
  • VRT vein refilling time
  • CRT capillary refilling time
  • Water accounts for up to 70 % of the mass of the human body and is essential for maintaining normal physiological functions. It is well known that dehydration, i. e. water loss, impares normal physiology. Physiological responses caused by dehydration depend on the amount of water loss. For example, water loss corresponding to 2 % decrease in body weight leads to reduced exercise performance and alertness. Further dehydration can lead to serious consequences, such as tissue damage, heart attack, stroke and even death.
  • Dehydration is encountered in a wide range of population from newborns to the elderly. Further, dehydration is particularly common under certain environmental and clinical conditions such as hot weather, vomiting, and diarrhea. There has been a steady increase in the number of hospitalizations due to dehydration in the past decade with substantial mortality occurred especially for elderly persons and children, respectively. Early detection of dehydration followed by proper care can reduce these numbers significantly because of the preventable and reversable nature of dehydration.
  • dehydration detection relies on laboratory tests or appearance of certain symptoms, e. g. thirst or a dry mouth.
  • symptomatic dehydration detection is inaccurate, subjective and unspecific and, thus, does not allow for dehydration quantification, i. e. determination of the degree of hydration/dehydration of the human body. Further, symptomatic dehydration detection usually detects a relatively late stage of dehydration.
  • laboratory tests performed by medical professionals are invasive and cost- and time-consuming.
  • vein refilling is typically performed for the elderly as well as for infants. In the case of the elderly, generally, small veins of the foot are used, while in the case of children, often, small capillaries below the fingernails are used. Visual observation of vein refilling, however, does not allow for accurate and in-time dehydration detection.
  • dehydration can be classified in four categories: (i) blood returns instantly, i. e. vein is filled, (ii) direction of blood flow is easily observed, i. e. vein is still filled, (iii) blood returns slowly, i. e. vein requires about 3 s to refill, and (iv) vein remains collapsed after release of occlusion.
  • a diagnostic medical instrument is described that is used in a capillary refilling time test procedure in which a skin area which overlies blood- filled capillaries, which normally display a pink color, is depressed to expel blood from the capillaries. When the pressure is released, blood is permitted to flow back into the capillaries, and, thus, the skin looses its white colour and regains its pink colour again.
  • the instrument includes a colour sensor trained on the skin area and responsive to light reflected therefrom. By measuring the time necessary for the skin to regain its pink colour, capillary refilling time is measured in order to determine the degree of hydration of the patient.
  • measurements with this instrument are not reliable and secure, especially when used for people with a darker skin type.
  • this object is addressed by a method for monitoring the degree of hydration of the human body based on measuring the time for refilling an occluded blood vessel with blood, the method comprising the following steps: occluding the blood vessel, in order to remove the blood from the blood vessel; releasing occlusion of the blood vessel in order to allow the blood to refill the blood vessel; irradiating tissue comprising the blood vessel with pulsed light during refill of the blood vessel; detecting an acoustical signal which is photoacoustically generated by absorption of each light pulse; analyzing the acoustical signal with respect to its amplitude; and measuring the time necessary for regaining a predefined amplitude of the acoustical signal after release of occlusion.
  • Photoacoustic measurements of vein refilling time or capillary refilling time take advantage of the fact that blood strongly absorbs visible and near-infrared (NIR) light.
  • NIR near-infrared
  • the detected acoustical signals vary significantly in amplitude, with a larger signal corresponding to a greater amount of blood in the capillaries. This process can be monitored with great temporal accuracy and, as a result, vein refilling time or capillary refilling time can be determined quantitatively by analyzing the intensity of the acoustical signal and, thus, the degree of hydration of the human body can be determined and indicated.
  • the term "amplitude" may be used for any measure or quantity of the acoustical signal.
  • the amplitude can be the peak height of the detected acoustical signal, the signal intensity, or an integral of amplitude or intensity over a predefined range.
  • the light pulse may comprise different wavelengths.
  • the light pulse comprises light of a predefined wavelength.
  • this wavelength relates to an absorption wavelength of blood.
  • the use of a predefined wavelength for the light pulse which relates to an absorption wavelength of blood allows for a better S/N-ratio.
  • the length of the light pulses can vary in a wide range.
  • the length of the light pulses is in the range from 1 - 500 ns. It has been found that such pulse durations provide for an accurate estimation of a temporal change of refill of the blood vessel.
  • energy per pulse may vary in a wide range, too. However, according to a preferred embodiment of the invention, energy per pulse is equal to or below 10 mJ/cm 2 . It has been observed that such pulse energies provide for sufficient acoustical signals without doing any harm to the human skin.
  • the ultrasound transducer frequency can be from 0.2 to 20 MHz.
  • the transducer can be either a single element transducer (focused or unfocused) or a transducer array.
  • the ambient temperature is measured in order to provide compensation for results. It has been observed that the measurement of the ambient temperature is advantageous for increasing the measuring accuracy, since vein refilling time and capillary refilling time are strongly affected by ambient temperature. Though it is preferred to provide a warm environment, this might not always be possible and, thus, the additional measurement of the ambient temperature can be used for standardization of the measured refilling times.
  • the predefined amplitude of the acoustical signal after release of occlusion which defines the end of the measured refilling time.
  • the predefined amplitude of the acoustical signal after release of occlusion is determined before occlusion as an absolute value or is determined as a constant value when no further temporal changes of the amplitude exceeding a predefined threshold occur.
  • the predefined value can be defined as the absolute amplitude before occlusion. Accordingly, in this case, the end of the refilling time can be determined when the original absolute signal is regained.
  • the predefined value is defined to be less than the absolute amplitude before occlusion.
  • the predefined value is defined as an absolute value which is calculated to be a predefined percentage of less than 100 % of the absolute value before occlusion. Further, it is especially preferred to define the predefined as a value in the range of 80 - 95 % of the absolute value before occlusion.
  • the predefined amplitude as a constant value when practically no further significant changes of the signal occur any more is advantageous, too, especially in cases where the original absolute value might not be regained, e. g. due to a change of posture of the patient.
  • a device for monitoring the degree of hydration of the human body based on measuring the time for refilling an occluded blood vessel with blood comprising: an occlusion means for occluding the blood vessel, in order to remove the blood from the blood vessel; a light source for radiating tissue comprising the blood vessel with pulse light; an acoustical detector for detecting an acoustical signal which is photoacoustically generated by absorption of each light pulse; an analyzer for analyzing the acoustical signal with respect to its amplitudes; a measuring unit for measuring the time necessary for regaining a predefined amplitude of the acoustical signal after release of occlusion.
  • Such device is especially meant to be used with a method as described above.
  • the occlusion means is formed by a transparent film which can act on the tissue.
  • a film with high mechanical strength is preferred in order to guarantee sufficient occlusion.
  • a material of the film is used which is transparent for the used optical waves or at least does not attenuate the irradiated light substantially.
  • a material is used which has a matched acoustic impedance, especially matched to the acoustic impedance of water with a low acoustic attenuation coefficient.
  • the film is thin compared to the ultrasound wavelength, matching problems can be omitted, to.
  • An especially suited material for the transparent film comprises polyester.
  • such a transparent film can be provided as an occlusion means which transmits visible and NIR light nearly undisturbed and which transmits acoustical signals like ultrasonic waves well, too.
  • the light incident on the human tissue and the acoustical signal received from the human tissue can propagate through air between the light source and the acoustical detector, respectively.
  • a coupling medium is provided between the irradiated tissue and the light source and/or the acoustical detector, respectively. It has been observed that especially water or oil are well suited as a coupling medium, respectively, especially when held at temperatures near normal body temperature.
  • the device for monitoring the degree of hydration based on a photoacoustical effect further comprises a temperature sensor for measuring the ambient temperature.
  • a laser especially a laser diode, a cluster of laser diodes (diode laser module), or an extended light source (such as light emitting diodes), is used as a light source, and/or an ultrasonic transducer is used as an acoustical detector.
  • Fig. 1 is a diagrammatic view of a device for monitoring the degree of hydration of the human body based on measuring the time for refilling occluded capillaries of a fingertip with blood according to a preferred embodiment of the invention
  • Fig. 2 shows the received photoacoustical signals for cases with and without blood in the capillaries of the fingertip, respectively.
  • Fig. 1 the measuring set up for a method and device for monitoring the degree of hydration of the human body based on measuring the capillary refilling time in a fingertip 2 is shown.
  • a light source 1 a laser is provided which sends out short laser pulses to illuminate the fingertip 2. Due to the absorption of the laser light in the fingertip 2 a photoacoustical signal within surface layers of the tissue is generated. This photoacoustical signal is recorded by an acoustical detector 3 which is formed by an ultrasonic transducer operated in listening mode.
  • the light source 1 and the acoustical detector 3 are synchronized with the help of a master clock 4 to ensure prompt data acquisition.
  • coupling medium 5 i. e. warm water
  • this coupling medium 5 is held at a temperature near normal body temperature.
  • an occlusion means 6 is provided which is formed by a thin transparent film. This occlusion means 6 can act on the fingertip 2 in such a way that capillaries are occluded and blood is expelled from the fingertip 2. After release of the occlusion means 6 measurement of capillary refilling time in order to determine the degree of hydration can be performed as follows:
  • the light source 1 emits ns-laser pulses at a wavelength of 532 nm at a light intensity of 2 mJ/cm 2 , through the coupling medium 5 and the transparent occlusion means 6, onto the fingertip 2.
  • Photoacoustical signals due to absorption of the laser pulses in the fingertip 2 are detected by the acoustical detector 3 which is coupled to the fingertip via the coupling medium 5 at a center frequency of 1 MHz.
  • the acoustical signal received by acoustical detector 3 is then transferred to a desktop housing 7 which incorporates an analyzer 8 for analyzing the acoustical signal with respect to its amplitude, and a measuring unit 9 for measuring the time necessary for regaining a predefined amplitude of the acoustical signal after release of occlusion by the occlusion means 6.
  • the desktop housing comprises a display 10 for displaying the degree of hydration estimated by the determined refilling time.
  • a temperature sensor 11 for measuring the ambient temperature is provided which is coupled to the measuring unit 9.
  • This temperature sensor 11 allows for standardization of the measured capillary refilling time depending on the ambient temperature which strongly influences refilling of capillaries and, thus, with the aid of such an ambient temperature measurement the measuring accuracy for the estimated degree of hydration is strongly increased. From Fig. 2, a photoacoustical signal received for one laser pulse in the case of capillaries filled with blood (full line) and capillaries without blood (doted line) can be seen.
  • the acoustical signal received after a laser pulse extends over a certain time range since the run time for an acoustical signal which is generated in deeper layers is longer than for such an acoustical signal which is generated in layers which are nearer to the surface.
  • the estimated depth is depicted where the acoustical signal is generated by absorption of the laser light.
  • the signal for capillaries filled with blood shows two main peaks located in Fig. 2.
  • the main peaks amplitude significantly decreases, in the present case by a factor of approximately 5.
  • the amount of blood in the capillaries can be estimated with great accuracy.

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  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Molecular Biology (AREA)
  • Animal Behavior & Ethology (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Medical Informatics (AREA)
  • Veterinary Medicine (AREA)
  • Surgery (AREA)
  • Biophysics (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Acoustics & Sound (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Radiology & Medical Imaging (AREA)
  • Ultra Sonic Daignosis Equipment (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
  • Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)

Abstract

L'invention concerne le domaine de la surveillance du degré d'hydratation du corps humain sur la base de la mesure du temps nécessaire au sang pour remplir de nouveau un vaisseau sanguin occlus, notamment par mesure du temps de remplissage d'une veine (VRT) et/ou du temps de remplissage capillaire (CRT). Selon un procédé de cette invention, un vaisseau sanguin est occlus pour retirer le sang du vaisseau, l'occlusion du vaisseau est libérée pour permettre au sang de remplir à nouveau le vaisseau sanguin, le tissu comprenant le vaisseau est exposé à une lumière pulsée pendant le remplissage du vaisseau, un signal acoustique généré sur le plan photo-acoustique par absorption de chaque impulsion de lumière est détecté, le signal acoustique est analysé par rapport à son amplitude, et le temps nécessaire au signal acoustique pour retrouver une amplitude prédéfinie après libération de l'occlusion est mesuré. Au moyen de ce procédé, il est possible de surveiller spécifiquement, avec précision et facilement le degré d'hydratation du corps humain.
PCT/IB2008/053589 2007-09-04 2008-09-04 Surveillance du degré d'hydratation du corps humain WO2009031119A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US96977007P 2007-09-04 2007-09-04
US60/969,770 2007-09-04

Publications (1)

Publication Number Publication Date
WO2009031119A1 true WO2009031119A1 (fr) 2009-03-12

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3698382A (en) * 1970-10-15 1972-10-17 William L Howell Device for measuring veno capillary filling time
WO2001006926A1 (fr) * 1999-07-26 2001-02-01 Cardiosense Ltd. Procede et appareil ameliores de detection d'etats medicaux de choc ou precedent le choc
US20040249290A1 (en) * 1999-07-26 2004-12-09 Cardiosense Non-invasive method and apparatus to detect and monitor early medical shock, and related conditions
US20080255433A1 (en) * 2007-04-11 2008-10-16 The Board Of Regents Of The University Of Texas Syatem Optoacoustic monitoring of multiple parameters

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3698382A (en) * 1970-10-15 1972-10-17 William L Howell Device for measuring veno capillary filling time
WO2001006926A1 (fr) * 1999-07-26 2001-02-01 Cardiosense Ltd. Procede et appareil ameliores de detection d'etats medicaux de choc ou precedent le choc
US20040249290A1 (en) * 1999-07-26 2004-12-09 Cardiosense Non-invasive method and apparatus to detect and monitor early medical shock, and related conditions
US20080255433A1 (en) * 2007-04-11 2008-10-16 The Board Of Regents Of The University Of Texas Syatem Optoacoustic monitoring of multiple parameters

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
IRINA V LARINA ET AL: "Real-time optoacoustic monitoring of temperature in tissues; Optoacoustic monitoring of temperature in tissues", JOURNAL OF PHYSICS D. APPLIED PHYSICS, IOP PUBLISHING, BRISTOL, GB, vol. 38, no. 15, 7 August 2005 (2005-08-07), pages 2633 - 2639, XP020083247, ISSN: 0022-3727 *
PETROV Y Y ET AL: "MULTIWAVELENGTH OPTOACOUSTIC SYSTEM FOR NONINVASIVE MONITORING OF CEREBRAL VENOUS OXAGENATION: A PILOT CLINICAL TEST IN THE INTERNAL JUGULAR VEIN", OPTICS LETTERS, OSA, OPTICAL SOCIETY OF AMERICA, WASHINGTON, DC, US, vol. 31, no. 12, 15 June 2006 (2006-06-15), pages 1827 - 1829, XP001243250, ISSN: 0146-9592 *
ROY G M KOLKMAN ET AL: "Photoacoustic determination of blood vessel diameter; Photoacoustic determination of blood vessel diameter", PHYSICS IN MEDICINE AND BIOLOGY, TAYLOR AND FRANCIS LTD. LONDON, GB, vol. 49, no. 20, 21 October 2004 (2004-10-21), pages 4745 - 4756, XP020023934, ISSN: 0031-9155 *

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