WO1996008197A1 - Dispositif de surveillance de mouvements a fibre optique pour la detection de la respiration et des battements du coeur et technique de traitement de signaux de capteurs biomedicaux contamines par des bruits dus aux mouvements du corps - Google Patents

Dispositif de surveillance de mouvements a fibre optique pour la detection de la respiration et des battements du coeur et technique de traitement de signaux de capteurs biomedicaux contamines par des bruits dus aux mouvements du corps Download PDF

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Publication number
WO1996008197A1
WO1996008197A1 PCT/US1995/011051 US9511051W WO9608197A1 WO 1996008197 A1 WO1996008197 A1 WO 1996008197A1 US 9511051 W US9511051 W US 9511051W WO 9608197 A1 WO9608197 A1 WO 9608197A1
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WO
WIPO (PCT)
Prior art keywords
die
noise signal
amplimde
subject
modal noise
Prior art date
Application number
PCT/US1995/011051
Other languages
English (en)
Inventor
Roger A. Stern
Eric G. Rawson
Michael Bennett
Jonathan R. Ferris
Charles F. Giese
Original Assignee
Alamed Corporation
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 Alamed Corporation filed Critical Alamed Corporation
Priority to AU35420/95A priority Critical patent/AU3542095A/en
Publication of WO1996008197A1 publication Critical patent/WO1996008197A1/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
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7203—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal
    • A61B5/7207—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal of noise induced by motion artifacts
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/0205—Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb
    • A61B5/1102—Ballistocardiography
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb
    • A61B5/113—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb occurring during breathing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P13/00—Indicating or recording presence, absence, or direction, of movement
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P13/00—Indicating or recording presence, absence, or direction, of movement
    • G01P13/008—Indicating or recording presence, absence, or direction, of movement by using a window mounted in the fluid carrying tube
    • G01P13/0086—Indicating or recording presence, absence, or direction, of movement by using a window mounted in the fluid carrying tube with photo-electric detection
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
    • G01P15/093—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by photoelectric pick-up
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
    • A61B2562/02—Details of sensors specially adapted for in-vivo measurements
    • A61B2562/0261—Strain gauges
    • A61B2562/0266—Optical strain gauges

Definitions

  • This invention relates to an improved fiber optic motion monitor for detecting changes in breathing or heartbeat of a subject, and in particular, small children.
  • This invention relates also to motion monitors for detecting body motions, such as those resulting from respiration and heartbeats, and, more particularly, to optical fiber motion monitors for detecting motion based on modal noise produced by minute motions of an optical fiber.
  • a significant cause of death in infants is "crib death” or sudden infant death syndrome (SIDS).
  • Medical authorities in general agree that some infants simply stop breathing during sleep (apnea) and that death can be prevented if the condition is detected and help is provided within a short time (some 30 to 60 seconds) by trained personnel or parents by using, for example, mouth-to-mouth resuscitation or similar techniques.
  • Apnea monitors already exist but their cost creates an affordability problem that limits their use.
  • the existing monitors produce considerable numbers of false alarms in infants with shallow breathing. Therefore, there has been a need for a breathing and/or heartbeat monitor which is cost efficient and reliable.
  • Optical fiber motion monitors are disclosed in the above-identified patents for use in detecting apnea, tachycardia, and bradycardia, particularly in infants.
  • Apnea is a condition in which a person simply stops breathing while sleeping
  • tachycardia and bradycardia are conditions in which the person's heartbeat rate rises dangerously high or falls dangerously low, respectively.
  • Apnea and bradycardia are a significant cause of death in infants (known as Sudden Infant Death Syndrome or SIDS), which can be prevented if these conditions are detected and help is provided in time.
  • SIDS Sudden Infant Death Syndrome
  • optical fiber motion monitors in which a few meters of an optical fiber are embedded in a subject's clothing or in a blanket, mattress cover, or other convenient bedding material.
  • Coherent light is injected into one end of the optical fiber and minute motions of the optical fiber generate changes in the fiber's speckle pattern. These changes are detected as modal noise by a photo- detector that is coupled to the other end of the optical fiber.
  • the speckle pattern has a granular mottled appearance which is created by constructive and destructive interference of light waves that are guided in each of the independent modes or optical paths within the optical fiber. Moving the optical fiber causes minute changes in many of the optical path lengths or causes waves that are guided in one mode to be coupled into another mode, with a resulting change in optical path length.
  • Such changes in optical path length need only be a fraction of a wavelength to substantially alter the resulting speckle pattern.
  • the modal noise signal detected by the photodetector is then processed by respiration and heartbeat detection and processing circuits to extract the subject's respiration and heartbeat rates.
  • one object of the present invention is to provide a novel fiber optic motion monitor which is cost effective and reliable.
  • Another object of the invention is to provide a novel fiber optic motion monitor having an increased sensitivity to body motions and an improved signal-to-noise ratio.
  • Another object of the invention is to provide a novel fiber optic motion monitor which is less susceptible to non-meaningful motions which might otherwise produce false alarms.
  • a still further object of die present invention is to provide a novel fiber optic motion monitor which can be shielded from accidental damage and from human fluids or other wastes which might damage the monitor.
  • a still further object of the present invention is to eliminate the need for relatively long lengths of optic fibers between the electro-optic components and the po ⁇ ion of the fiber which moves in response to the mechanical motions to be detected, i.e., those caused by the breathing and/or heartbeat of the subject.
  • Yet another object to be achieved by the present invention is to provide a novel fiber optic motion monitor which employs a mechanical advantage in transferring the motion of a movable member caused by motion of the subject into a magnified motion of the fiber coil used to detect the motion.
  • a light source an optical fiber waveguide having an input end coupled to die light source, an output end, and a multi-loop sensing coil intermediate the input and output ends; means for transmitting a motion from an object to the sensing coil, including a movable member and a resistance member between which the sensing coil is disposed so that when motion of the object results in movement of the movable member, the loops of the multi-loop sensing coil are pressed against the resistance member and thereby change shape; photodetector means positioned proximate to the output end of the optical fiber waveguide for receiving therefrom a speckle pattern of light, which pattern changes in response to movement of the multi-loop sensing coil, the photodetector means generating electrical signals representative of changes in the speckle patterns; and output means coupled to the photodetector means for producing an ou ⁇ ut indicative of motion of the object based on the electrical signals generated by the photodetector means.
  • a further aspect of the present invention resides in a technique for identifying portions of a modal noise signal that are contaminated with body movement noise and then disregarding these contaminated portions during further processing of the signal.
  • the technique generates logic signals that indicate whether a subject is moving (SIM), me subject is resting quietly (SRQ), or the subject is out of bed/deceased (SOBD).
  • SIM moving
  • SRQ me subject is resting quietly
  • SOBD bed/deceased
  • the logic signals SRQ, SIM and SOBD are generated by a threshold comparator and logic unit using two measured values, the average amplitude of the modal noise signal (AMP) and the amplitude of the high-frequency content of the signal (HFC).
  • the AMP and HFC values are computed by an average amplitude detector and a high- frequency amplitude detector, respectively.
  • die amplitude (AMP) and high-frequency content (HFC) values are compared with upper and lower amplitude and high-frequency -content thresholds.
  • the subject if the amplitude (AMP) of the modal noise signal is greater than an upper amplitude threshold (UAMPT) and the high-frequency content (HFC) of the modal noise signal is greater than an upper high- frequency-content threshold (UHFCT), the subject is classified as moving (SIM). If d e amplitude (AMP) of the modal noise signal is less than a lower amplitude threshold (LAMPT), the subject is classified as being out of bed/deceased (SOBD). If the amplitude (AMP) of the modal noise signal is between the upper and lower amplitude thresholds, the subject is classified as resting quietly (SRQ).
  • UAMPT upper amplitude threshold
  • HFC high-frequency content
  • UHFCT upper high- frequency-content threshold
  • the subject is classified as being out of bed/deceased (SOBD) only if d e amplitude (AMP) of the modal noise signal is less than a lower amplitude threshold (LAMPT) and d e high-frequency content (HFC) of the modal noise signal is greater than a lower high-frequency-content threshold (LHFCT).
  • SOBD bed/deceased
  • a modal noise signal in accordance witii the present invention can also be used to prevent body movement noise from affecting information extracted from other contaminated biomedical sensor signals, such as those generated by EKG and EEG sensor systems and blood oximetry and plethysmographic sensors.
  • the present invention can also be used to monitor patients in a hospital or nursing home to provide patient status at a remote nursing station.
  • Figure 1 shows a first preferred embodiment according to the present invention illustrating die sensing section of the optical fiber waveguide located between die " * flexible tympanum constituting the movable member and the relatively rigid bottom plate constituting the resistance member;
  • Figure 2 illustrates ie basic elements of me invention including the opto- electrical system for detecting motion of the sensing coil of the optical fiber waveguide;
  • Figure 3 illustrates a front view of d e display device used for displaying the breadiing and/or heart rate of die patient
  • Figure 4 illustrates a second preferred embodiment including an intermediate lever attached to a center portion of the tympanum for pivoting against the sensing coil of the optical fiber waveguide;
  • Figure 5 illustrates a third embodiment according to the present invention including an expandable balloon disposed between die tympanum and a base plate for imparting horizontal displacements to the sensing coil of me optical fiber waveguide;
  • Figure 6A illustrates a fourth embodiment according to die present invention wherein a pneumatic or hydraulic reservoir is provided between he tympanum and a base member for imparting horizontal force to a piston which presses against the sensing coil of die optical fiber waveguide;
  • Figure 6B illustrates a modification of the fourth embodiment which includes a flexible bellows assembly in place of the piston shown in Figure 4A;
  • Figure 7 illustrates a fifth embodiment according to me present invention, similar to the second embodiment, but with a 90° rotator device coupled between the sensing coil of the optical fiber waveguide and the end of the lever used to impart movement to d e sensing coil;
  • Figure 8 illustrates a sixth emhodimenr according to me present invention wherein the sensing coil is positioned horizontally between radially oriented finger projections or, alternatively, attached to the tympanum and d e resistance member, so that the sensing coil at rest follows a path which undulates slightly out of the nominal plane of the sensing coil;
  • Figure 9 illustrates an assembled side view of the sixth embodiment
  • Figure 10 is a block diagram of a preferred embodiment of die present invention.
  • FIG. 11 is a flowchart of one preferred technique of the present invention.
  • FIG. 12 is a flowchart of another preferred technique of the present invention.
  • Figure 13 is a block diagram of ano ⁇ ier preferred embodiment of die present invention.
  • a relatively rigid base plate 3 functions as a resistance member which can be, for example, 16" X 24" and constructed of l/8th inch plywood, for example, supports a similar relatively less rigid top plate as die tympanum plate, at the four corners diereof by four rigid spacers 5.
  • the top plate, or tympanum plate 2 may be die same size as the base plate while of somewhat thinner plywood so as to be more flexible, i.e.
  • die tympanum plate 2 could be made from a thin sheet of fiberglass, PLEXIGLASS, resin material, plastic membrane, or a flexible metal plate at a thickness of, for example, l/16th inch.
  • PLEXIGLASS is a trademark owned by Rohm and Haas, which is generally known in the art and comprises a polymediyl methacrylate. As such it is a resin compound and hereafter included in die term resin .
  • a sensing coil 4 of N turns of a multi-mode optical fiber is positioned between die tympanum plate 2 and base plate 3 in such a position that opposite sides of die coil engage respective ones of die upper and lower plates 2, 3.
  • diey can be fashioned from a single fiber, looped several times, with die light passing sequentially through each loop.
  • the diameters of me loops of die fiber coil constituting the sensing coil 4 are somewhat larger man die space between die two plates, so that die natural flexure of the fibers tends to hold die coil in position between me plates.
  • the coils could be attached to one plate with a small amount of glue, so tiiat die opposite edge of die coil rests widiin a suitable dent provided on die opposite plate.
  • FIG. 2 shows die basic opto-electric components of die present invention including laser 21, optical fiber waveguide 22, multi-loop sensing coil 4, photodetector 23 and an output circuit 24 for receiving electrical signals from the photodetector and analyzing the signals to determine information about the breadiing and/or heartbeat of die subject.
  • Movement or bending of die sensing coil 4 causes changes in me speckle pattern output from me output end of die optical fiber waveguide 22 and received by die photodetector 23, as disclosed in me prior patents.
  • the output circuit could be as simple as the amplifier and loudspeaker disclosed in U.S. Patent No. 5,436,444, or in d e more complicated breathing and heartbeat analysis circuits of U.S. Patent No. 5,291,013.
  • the processing techniques and/or the output circuits of die cross-referenced prior applications can be utilized in the present invention.
  • a display device 27 is connected to d e output circuit 24 for receiving information output to me display device in order to display die detected changes in d e breath rate and heart rate of d e patient.
  • the fiber optic sensor 1 would not require d e attachment of sensors to the patient being monitored.
  • the display device 27 may be located adjacent to die patient's bed, thereby providing quick assessment of die current status of die patient's breath rate and/or heart rate.
  • d e recent history of heart rate and bread ing of die patient could also be displayed, mereby improving the accuracy of me assessment of die patient's condition and reduction in die time necessary for an operator to perform the routine measurements on the patients.
  • me average heart rate and average breath rate are calculated using me teachings of the prior cross-referenced applications, notably d ose of U.S. Patent No. 5,291,013.
  • the averaging is performed for die most recent time interval of appropriate predetermined duration. For example, a preferable duration for heart rate averaging would be 5-20 seconds, and a preferable duration for breath rate averaging would be 0.5-20 minutes. These time intervals could be preset by die healthcare professional to any convenient and appropriate values desired.
  • the average value of heart rate and bream rate are displayed in a conveniently sized display box, advantageously a back lit liquid crystal display (LCD) unit, showing die current average values and updating diem periodically (for example, every second, or every few seconds, etc.).
  • LCD liquid crystal display
  • the care giver can see immediately upon entering die patient's room what the current average breath and heart rates are. Furthermore, since me values displayed represent averages over a longer time period than a care giver (typically die ward nurse) can normally allow to each patient, the measurements will be more accurately representative of me patient's true status. Finally, because me care giver does not need to awaken or odierwise disturb me patient, the heart rate and bream rate values they record for the patient are free from distortions due to intervention by die care giver.
  • a portion of the LCD display would present a graph of die recent history of eidier or bodi of die heart rate and bread rate. In is manner, past readings over an extended time period (for example, one hour, several hours, etc.) would be displayed as an analog graph on separate areas of die LCD display.
  • die care giver would have at his disposal not only me current value, but would also be able to observe die current history which would indicate whedier mere had been any unusual perturbations, possibly short-lived, in the period since me patient had been last observed. It will be understood by diose skilled in die art that numerous variations of die above teachings of die display device are possible.
  • the device could be connected to die existing data monitoring network in the hospital or nursing home and die data could dius be stored in a permanent data file.
  • Anod er preferred embodiment would include alarm capabilities, sounding an alarm locally or at an adjacent nursing station, if apneas of longer than a preset during (for example, 20 or 30 seconds) occur, or if heart rates exceeded or subseded preset rate diresholds, as described in die cross-referenced applications.
  • die wall-mounted LCD display could feature a sensor (an IR optical detector, for example) which would allow die care giver to switch die display on when die care giver enters die room, using a convenient hand-held or lapel mounted IR emitter device.
  • Figure 3 shows one example of a design for die LCD display device 27, showing the bream rate and heart rate over a predetermined period of time. It should also be noted that the LCD display can be applied to the monitoring devices of prior U.S. Patent No. 5,436,444, 5,291,023 and 5,212,379.
  • a second embodiment according to the present invention includes an intermediate lever 7 attached to a center portion of die tympanum plate 2 which pivots at a pivoting point connected to fulcrum 6.
  • An end of me lever 7 which contacts sensing coil 4 of die optical fiber waveguide imparts vertical force to the sensing coil 4 at a first side thereof , while the opposite side of me sensing coil 4 engages base plate 3.
  • die lever 7 is positioned relative to die fulcrum 6 such diat die short lever arm is displaced vertically by motions of the tympanum plate 2.
  • the end of die long lever arm is attached to peripheral portions of me loops constituting me sensing coil 4. This results in fiber motions which are amplified by me mechanical advantage of die lever 7.
  • die vertical movements imparted to die tympanum plate 2 are magnified by d e vertical pressing force imparted at die sensing coil 4 of me optical fiber waveguide.
  • the fiber sensing coil 4 could advantageously be attached to eid er me lever 7 or the base plate 3 with a small amount of glue or cement, and rest within a detent on me opposite contact point. To assure contact, the coil 4 could advantageously be slightly compressed in its resting state between lever 7 and base plate 3.
  • FIG. 5 Anodier embodiment according to the present invention is illustrated in Figure 5, which shows an expandable balloon 8 located between die tympanum plate 2 and die base plate 3.
  • the expandable balloon 8 expands or shrinks in the horizontal direction thus imparting horizontal forces to the sensing coil 4 of d e optical fiber waveguide.
  • d e opposite side of the sensing coil 4 of the optical fiber waveguide engages die resistance member 9.
  • the vertical motions due to breathing and heartbeat are translated into horizontal forces to be imparted to e sensing coil 4 of me optical fiber.
  • Vertical motions of the tympanum plate 2 result in corresponding radial motions parallel to me planes of the plates at its horizontal periphery.
  • die peripheral sides of one or more loops can be attached to ⁇ iis peripheral rim of the expandable balloon, and die opposite peripheral sides of the loop(s) can be attached to die resistance member 9.
  • die resistance member 9 The die resistance members 9 A can be positioned about diree sides of me balloon to constrain nearly all of its horizontal motion to occur near the fiber sensor loop attachment point.
  • the expandable balloon 8 can be replaced by a pneumatic or hydraulic reservoir 11 which serves to impart horizontal motion to a piston 10 coupled between the reservoir 11 and die sensing coil 4 of the optical fiber waveguide.
  • the resistance member 9 is provided in a similar location as shown in Figure 3 described above.
  • the displacement of me piston is magnified over diat of die tympanum plate 2 by the ratio of the cross-sectional area of die reservoir to the cross- sectional area of die reservoir to die cross-sectional area of die piston 10. In diis manner, a mechanical advantage of up to several hundred magnification units can be achieved.
  • the piston drives one rim of a fiber coil, the opposite rim being anchored to die resistance member 9.
  • die piston 10 of Figure 6A can be replaced widi a flexible bellows device 10A.
  • a sixth embodiment according to die present invention utilizes changes in bending of the sensing coil 4 which is disposed between die upper and lower plates 2, 3 and more specifically between radially extending finger projections 15 which extend from the inner surfaces of die plates 2, 3.
  • die sensing coil 4 is positioned horizontally between die radially oriented fingers. It is additionally pointed out that the sensing coil could be attached to me upper plate 2 and die lower plate 3 (which functions as the resistance member) such that die sensing coil 4 at rest follows a padi which undulates slightly out of e nominal plane of the sensing coil, as can be seen in Figure 9.
  • diat die orthogonal projections of me fingers 15 on the top and bottom plates 2, 3 do not overlap, i.e., die fingers of the top and bottom plates are angularly offset in order to provide a desirable degree of undulation of die sensing coil out of its natural plane when die sensor is assembled and in its resting state.
  • Figure 9 illustrates an assembled side view of die sixtii embodiment which illustrates the manner by which die horizontal coil is pressed in up and down directions by die radially extending fingers. Small vertical motions of me upper plate 2 upwards and downwards cause d e fiber undulation bending to decrease and increase, respectively. While Figures 8 and 9 illustrate only eight radial fingers for simplicity, the overall sensitivity can be increased by using more fingers with tens, hundreds or even thousands of fingers being suitable.
  • the upper and lower plates 2, 3 may be provided widi die plurality of rigid spacers 5 located near die corners or edges of die plates in order to hold the two plates a fixed distance apart at their edges,
  • An advantage of die invention is diat die sensitivity to vibration of die tympanum plate 2 is proportional to N, me number of loops in e fiber coil sensing coil 4, and diis number can advantageously be made quite large; values of N on order of 10, 100, or even 1000, or possibly more, are practical, the optimal number N being selected to provide an appropriate balance between manufac ring complexity and materials cost on me one hand and sensitivity to mechanical motions of the tympanum on the other.
  • a further advantage of this invention is that me optical fiber waveguide is sheltered from non-meaningful motions because of me relative rigidity of die plates with regard to any motions (for example, shear motions) other than vertical motions of me tympanum center, as compared to tine sensor pad of the above-noted applications. Since the fiber loop sensing coil 4 is compressed only in response to the normal lowest order vibration mode of die tympanum plate 2, it is relatively insensitive to motions along the odier two axes.
  • a further advantage of the present invention is that die fiber optic motion monitor can be located beneath die mattress, shielding it from accidental damage and from human fluids or odier wastes which might damage the monitor if located on a pad above the mattress.
  • electro-optical components the diode laser and die photodetector
  • the electro-optical components can be located between the upper and lower plates and adjacent to die sensing coil of the optical fiber waveguide, eliminating the use of long fiber lead lengdis between die electro-optical components and me portions of the fiber diat actually move in response to me mechanical motions to be detected, i.e. , diose due to breathing and heartbeat.
  • a still further advantage of die present invention is diat die sensitivity can be further improved by creating a mechanical advantage in translating die vertical flexural motion of die tympanum plate 2 into a magnified motion of the sensing coil of the optical fiber waveguide.
  • Systems to achieve diis can use die principles of levers, pneumatic systems or hydraulic systems.
  • one aspect of me present invention is embodied in a technique for identifying portions of a modal noise signal diat are contaminated widi body movement noise and dien disregarding diese contaminated portions during further processing of die signal.
  • the technique generates logic signals diat indicate whether a subject is moving (SIM), the subject is resting quietly (SRQ), or die subject is out of bed/deceased (SOBD).
  • SIM moving
  • SRQ resting quietly
  • SOBD die subject is out of bed/deceased
  • Normal processing of the modal noise signal such as extraction of the subject's respiration and heartbeat rates, is suspended while die subject is moving (SIM is true) or die subject is out of bed/deceased (SOBD is true), and processing is resumed when die subject is resting quietly (SRQ is true).
  • an optical fiber motion monitor 30 in accordance widi die present invention includes an optical fiber sensor pad 32 having a few meters of a multi mode optical fiber 34 embedded in die sensor pad, a coherent light source 36 such as an injection laser diode coupled to one end of die optical fiber 34 for injecting coherent light into the optical fiber, and a photodetector/amplifier/filter 38 for detecting, amplifying and filtering a modal noise signal produced by minute motions of the multi mode optical fiber 34.
  • the amplified and filtered modal noise signal is dien digitized by an A/D converter 50 and applied to a respiration detection and processing circuit 52 and a heartbeat detection and processing circuit 54 for extraction of respiration and heartbeat rates, respectively, from the modal noise signal.
  • a pair of AND gates 56 allows d e digitized modal noise signal to be applied to d e processing circuits 52, 54 only when d e subject is resting quietly (SRQ is true).
  • Breath display and alarm unit 58 and heart display and alarm unit 60 provide displays for die respiration and heartbeat rates, respectively, and generate appropriate alarms if these rates fall outside predetermined ranges. Further details of this portion of die invention are set forth in die above-identified patents, which are hereby incorporated by refer ⁇ ence.
  • the logic signals SRQ, SIM and SOBD are generated by a threshold comparator and logic unit 62 using two measured values, the average amplitude of the modal noise signal (AMP) and die amplitude of the high-frequency content of me signal (HFC).
  • the AMP and HFC values are computed by an average amplitude detector 64 and a high- frequency amplitude detector 66, respectively.
  • die amplitude (AMP) and high-frequency content (HFC) values are compared widi upper and lower amplitude and high-frequency-content diresholds.
  • AMP amplitude of die modal noise signal
  • UAMPT upper amplitude direshold
  • HFC die high-frequency content
  • UHFCT man an upper high-frequency -content direshold
  • SRQ resting quietly
  • me subject is classified as being out of bed/deceased (SOBD) only if die amplimde (AMP) of die modal noise signal is less dian a lower amplitude threshold (LAMPT) and die high-frequency content (HFC) of die modal noise signal is greater dian a lower high-frequency-content direshold (LHFCT).
  • SOBD bed/deceased
  • AMP die amplimde
  • HFC die high-frequency content
  • LHFCT low high-frequency-content direshold
  • the amplimde (AMP) and high-frequency content (HFC) values can be measured by many different methods.
  • the amplitude (AMP) of die modal noise signal is a measure of die average amplimde of me raw or unprocessed modal noise signal.
  • a first method of measuring average amplitude involves measuring the minimum and maximum amplitudes of die modal noise signal over some sampling period and dien taking die difference between the two values. This computation, which is actually a peak-to-peak amplimde computation, provides a reasonably good approximation of the average amplimde of the noise signal.
  • a second and more accurate method of measuring average amplimde involves computing an RMS deviation of die modal noise signal* from its mean value. Other methods of measuring die amplitude (AMP) value will be obvious to one skilled in die art.
  • the high-frequency content (HFC) of die modal noise signal is a measure of the amplimde of die high-frequency content of die raw or unprocessed modal noise signal.
  • a first method of measuring die amplimde of die high-frequency content involves counting me number of zero crossings or sign reversals of die first derivative of die noise signal over some sampling period. The technique shown in Figure 12, using die lower high-frequency-content direshold (LHFCT) along widi die lower amplimde direshold (LAMPT) to classify die subject as being out of bed or deceased (SOBD), is preferred when diis method is used.
  • a second method of measuring me amplimde of the high-frequency content involves counting me number of zero crossings of me noise signal (not its derivative) over some sampling period.
  • a diird and more accurate method of measuring die amplimde of die high-frequency content involves filtering die modal noise signal wid a high-pass or band pass filter to remove the low-frequency components of me signal.
  • This high-frequency -component signal is men rectified and filtered widi a low- pass filter.
  • the resulting signal provides the equivalent of an envelope following of die high-frequency-component signal.
  • a fourth and even more accurate method of measuring die amplimde of die high-frequency content is to measure me spectral content of d e noise signal directly using any suitable fast Fourier transform (FFT).
  • FFT fast Fourier transform
  • Other methods of measuring me high-frequency content (HFC) value will be obvious to one skilled in d e art.
  • predetermined direshold values can be programmed into me motion monitor at me time of manufacture if variations in optical fiber response from one monitor to another are small, or customized direshold values can be programmed into me motion monitor after me device is tested if variations in optical fiber response are large.
  • a modal noise signal in accordance widi die present invention can also be used to prevent body movement noise from affecting information extracted from other contaminated biomedical sensor signals, such as diose generated by EKG and EEG sensor systems and blood oximetry and plethysmographic sensors.
  • This preferred embodiment of me present invention includes a biomedical sensor 70, an A/D converter 72 for digitizing die sensor signal, an AND gate 74 having die digitized sensor signal and the SRQ logic signal as inputs, and an information extraction circuit 76.
  • the present invention can also be used to monitor patients in a hospital or nursing home to provide patient status to a remote nursing station.
  • die present invention has been described as implemented in digital form, the invention can be implemented in analog form using comparators and other analog elements, and omitting me A/D converters 50, 72. Furthermore, the techniques described widi respect to Figures 10 to 13 are not to be read as being limited in application to die embodiments illustrated in Figures 1 to 9.
  • diat the present invention represents a significant advance in die field of optical fiber motion monitors.
  • several preferred embodiments of the invention have been shown and described, it will be apparent diat odier adaptations and modifications can be made widiout departing from the spirit and scope of die invention. Accordingly, die invention is not to be limited, except as by die following claims.

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Abstract

Dispositif de surveillance de mouvements à fibre optique qui comporte une source lumineuse (21) et un guide d'ondes (22) à fibre optique, avec une partie de détection (4) située entre une extrémité d'entrée et une extrémité de sortie. Un dispositif (3) de transmission de mouvement est couplé à la partie de détection du guide d'ondes à fibre optique pour transmettre le mouvement d'un patient à la partie de détection. Un photodétecteur (23) est placé pour recevoir une configuration de points lumineux qui se modifie en réponse aux mouvements du patient et de la partie de détection. La partie de détection (4) du guide d'ondes à fibre optique comporte une pluralité de boucles qui sont placées entre une plaque (2) relativement souple et un élément de résistance (3), de telle manière que les boucles changent de forme lors des mouvements du patient dus à sa respiration et/ou aux battements de son c÷ur. Une technique permettant d'identifier des parties d'un signal de bruit modal qui sont contaminées par des bruits de mouvement corporel et ensuite d'éliminer ces parties contaminées au cours du traitement ultérieur est également décrite.
PCT/US1995/011051 1994-09-12 1995-09-12 Dispositif de surveillance de mouvements a fibre optique pour la detection de la respiration et des battements du coeur et technique de traitement de signaux de capteurs biomedicaux contamines par des bruits dus aux mouvements du corps WO1996008197A1 (fr)

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AU35420/95A AU3542095A (en) 1994-09-12 1995-09-12 Fiber optic motion monitor for breath and heartbeat detection and a technique for processing biomedical sensor signals contaminated with body movement noise

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US304,177 1994-09-12
US34306494A 1994-11-21 1994-11-21
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WO1999023941A1 (fr) * 1997-11-10 1999-05-20 Fields, Eden, Elizabeth Dispositif intra-auriculaire integre de surveillance des signes vitaux
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US7306903B1 (en) 1995-07-26 2007-12-11 Curis, Inc. Methods and compositions for identifying morphogen analogs
WO2007140210A3 (fr) * 2006-05-24 2008-02-07 Tarilian Laser Technologies Lt PROcédé de détection d'un signe vital optique et dispositif de mesure
US7463796B2 (en) 2007-01-31 2008-12-09 Tarilian Laser Technologies, Limited Waveguide and optical motion sensor using optical power modulation
EP2142095A1 (fr) * 2007-05-02 2010-01-13 Earlysense Ltd. Suivi, prévision et traitement d'épisodes cliniques
US8840564B2 (en) 2004-02-05 2014-09-23 Early Sense Ltd. Monitoring a condition of a subject
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US8942779B2 (en) 2004-02-05 2015-01-27 Early Sense Ltd. Monitoring a condition of a subject
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GB2531817A (en) * 2014-11-03 2016-05-04 Westerngeco Seismic Holdings Ltd Accelerometer
WO2017035452A1 (fr) * 2015-08-27 2017-03-02 Darma Inc. Capteurs à fibre optique et procédés de surveillance de micro-mouvements
US9883809B2 (en) 2008-05-01 2018-02-06 Earlysense Ltd. Monitoring, predicting and treating clinical episodes
US10172593B2 (en) 2014-09-03 2019-01-08 Earlysense Ltd. Pregnancy state monitoring
US10292625B2 (en) 2010-12-07 2019-05-21 Earlysense Ltd. Monitoring a sleeping subject
CN110231468A (zh) * 2019-06-30 2019-09-13 东南大学苏州医疗器械研究院 一种基于光纤测量的三维心脏芯片及其检测方法
WO2019205174A1 (fr) * 2018-04-28 2019-10-31 深圳市大耳马科技有限公司 Système et procédé de mesure de paramètres de conduction d'ondes d'impulsion
US10575829B2 (en) 2014-09-03 2020-03-03 Earlysense Ltd. Menstrual state monitoring
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Publication number Priority date Publication date Assignee Title
US6103491A (en) * 1995-07-26 2000-08-15 Creative Biomolecules, Inc. Methods and compositions for identifying morphogen analogs
US7306903B1 (en) 1995-07-26 2007-12-11 Curis, Inc. Methods and compositions for identifying morphogen analogs
US6090544A (en) * 1995-07-26 2000-07-18 Creative Biomolecules, Inc. Methods and compositions for identifying morphogen analogs
WO1999017658A1 (fr) * 1997-10-03 1999-04-15 Eth Transfer Procede pour mesurer au moins le rythme respiratoire d'un etre vivant
WO1999023941A1 (fr) * 1997-11-10 1999-05-20 Fields, Eden, Elizabeth Dispositif intra-auriculaire integre de surveillance des signes vitaux
AT409714B (de) * 2001-03-16 2002-10-25 Hiesmayr Walter Apparatur zur nichtinvasiven messung von muskelkontraktionen und deren diagnostischen auswertung
US9131902B2 (en) 2004-02-05 2015-09-15 Earlysense Ltd. Prediction and monitoring of clinical episodes
US8942779B2 (en) 2004-02-05 2015-01-27 Early Sense Ltd. Monitoring a condition of a subject
US8840564B2 (en) 2004-02-05 2014-09-23 Early Sense Ltd. Monitoring a condition of a subject
US9026199B2 (en) 2005-11-01 2015-05-05 Earlysense Ltd. Monitoring a condition of a subject
WO2007140210A3 (fr) * 2006-05-24 2008-02-07 Tarilian Laser Technologies Lt PROcédé de détection d'un signe vital optique et dispositif de mesure
US8360985B2 (en) 2006-05-24 2013-01-29 Tarilian Laser Technologies, Limited Optical vital sign detection method and measurement device
EP2462864A1 (fr) * 2006-05-24 2012-06-13 Tarilian Laser Technologies, Limited Procédé de détection d'un signe vital optique et dispositif de mesure
US8343063B2 (en) 2006-05-24 2013-01-01 Tarilian Laser Technologies, Limited Optical vital sign detection method and measurement device
US7657135B2 (en) 2007-01-31 2010-02-02 Tarilian Laser Technologies, Limited Waveguide and optical motion sensor using optical power modulation
US8467636B2 (en) 2007-01-31 2013-06-18 Tarilian Laser Technologies, Limited Optical power modulation vital sign detection method and measurement device
US8111953B2 (en) 2007-01-31 2012-02-07 Tarilian Laser Technologies, Limited Optical power modulation vital sign detection method and measurement device
US7822299B2 (en) 2007-01-31 2010-10-26 Tarilian Laser Technologies, Limited Optical power modulation vital sign detection method and measurement device
US7463796B2 (en) 2007-01-31 2008-12-09 Tarilian Laser Technologies, Limited Waveguide and optical motion sensor using optical power modulation
US9277868B2 (en) 2007-01-31 2016-03-08 Tarilian Laser Technologies, Limited Optical power modulation vital sign detection method and measurement device
EP2142095A1 (fr) * 2007-05-02 2010-01-13 Earlysense Ltd. Suivi, prévision et traitement d'épisodes cliniques
US9883809B2 (en) 2008-05-01 2018-02-06 Earlysense Ltd. Monitoring, predicting and treating clinical episodes
US8882684B2 (en) 2008-05-12 2014-11-11 Earlysense Ltd. Monitoring, predicting and treating clinical episodes
US8998830B2 (en) 2008-05-12 2015-04-07 Earlysense Ltd. Monitoring, predicting and treating clinical episodes
US11147476B2 (en) 2010-12-07 2021-10-19 Hill-Rom Services, Inc. Monitoring a sleeping subject
US10292625B2 (en) 2010-12-07 2019-05-21 Earlysense Ltd. Monitoring a sleeping subject
EP2756800B1 (fr) * 2013-01-22 2022-06-29 Envitec-Wismar GmbH Moniteur de pulsoximétrie
US10172593B2 (en) 2014-09-03 2019-01-08 Earlysense Ltd. Pregnancy state monitoring
US10575829B2 (en) 2014-09-03 2020-03-03 Earlysense Ltd. Menstrual state monitoring
GB2531817A (en) * 2014-11-03 2016-05-04 Westerngeco Seismic Holdings Ltd Accelerometer
GB2531817B (en) * 2014-11-03 2019-12-04 Westerngeco Seismic Holdings Ltd Accelerometer
US10768197B2 (en) 2014-11-03 2020-09-08 Schlumberger Technology Corporation Accelerometer
CN107427260A (zh) * 2015-08-27 2017-12-01 深圳市大耳马科技有限公司 光纤传感器以及监测微运动的方法
US10743797B2 (en) 2015-08-27 2020-08-18 Shenzhen Darma Technology Co. Ltd. Fiber-optic sensors and methods for monitoring micro-movements
JP2018532987A (ja) * 2015-08-27 2018-11-08 深▲せん▼市大耳馬科技有限公司Ｓｈｅｎｚｈｅｎ Ｄａｒｍａ Ｔｅｃｈｎｏｌｏｇｙ Ｃｏ．，Ｌｔｄ． 光ファイバーセンサ及び微動の監視方法
WO2017035452A1 (fr) * 2015-08-27 2017-03-02 Darma Inc. Capteurs à fibre optique et procédés de surveillance de micro-mouvements
WO2019205174A1 (fr) * 2018-04-28 2019-10-31 深圳市大耳马科技有限公司 Système et procédé de mesure de paramètres de conduction d'ondes d'impulsion
CN110231468A (zh) * 2019-06-30 2019-09-13 东南大学苏州医疗器械研究院 一种基于光纤测量的三维心脏芯片及其检测方法

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