US007650176B2
`
`a2) United States Patent
`US 7,650,176 B2
`(0) Patent No.:
`*Jan. 19, 2010
`(45) Date of Patent:
`Sarussi et al.
`
`(54) PHYSIOLOGICAL STRESS DETECTOR
`DEVICE AND SYSTEM
`
`(75)
`
`Inventors:
`
`Israel Sarussi, HofAza (IL); Yehuda
`Heimenrath, Neve Dekalim (IL)
`
`(73) Assignee: SPO Medical Equipment Ltd., Kfar
`Saba(IL)
`
`:
`(*) Notice:
`
`:
`:
`:
`:
`Subjectto any disclaimer,the term ofthis
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 449 days.
`This patent is subject to a terminal dis-
`claimer.
`
`(21) Appl. No.: 11/612,641
`
`(22)
`
`Filed:
`
`Dec. 19, 2006
`
`(65)
`
`Prior Publication Data
`US 2009/0018421 Al
`Jan. 15, 2009
`oo.
`Related U.S. Application Data
`(63) Continuation of application No. 10/390,169, filed on
`Mar. 18, 2003, now Pat. No. 7,171,251, which is a
`continuation-in-part of application No. 09/147,683,
`filed on Feb. 1, 2000, now Pat. No. 6,553,242.
`
`(51)
`
`Int. Cl.
`2006.01
`AG6IB 5/1455
`(2006.01)
`AGIB 5/02
`(52) US. Chee 600/324; 600/330; 600/502
`
`(58) Field of Classification Search ................. 600/322,
`600/323, 330, 336, 324, 502
`See application file for complete search history.
`,
`References Cited
`U.S. PATENT DOCUMENTS
`
`(66)
`
`. 600/330
`.....
`5/1978 Kofsky etal.
`4,086,915 A *
`
`... 600/323
`5/1981 Hamaguri
`.........
`4,266,554 A *
`... 600/330
`4/1989 Fricketal. .....
`4,824,242 A *
`5,351,685 A * 10/1994 Potratz ..........
`... 600/330
`... 600/323
`5,431,170 A *
`7/1995 Mathews...
`
`...seesssseeeeeesee 600/330
`6,553,242 BL*
`4/2003 Sarussi
`
`
`
`* cited by examiner
`.
`Primary Examiner—Enic F Winakur
`(74) Attorney, Agent,
`or Firm—Daniel
`AlphaPatent Associates Ltd.
`
`.
`J. Swirsky;
`
`(57)
`
`ABSTRACT
`
`oo
`.
`.
`.
`A non-invasive device and a system for monitoring and mea-
`suring blood saturation andheart pulserate ofa baby or infant
`is provided. The device includes a housing unit configured to
`be integrated within apparatus, which is attachable proximate
`to a limb being measured. The housing unit includesat least
`one light source, providing light directed toward the surface
`ofthe limb,a light detector spaced apart from thelight source
`and sensitive to intensity levels ofthe light reflected from the
`limb and a processing unit for processing the intensity signals
`received from the light detector for producing output signals.
`The device may determinethe level of the blood constituent
`and mayalso usethis level for monitoring and/or to activate
`an alarm whenthe level falls outside a predetermined range.
`Pp
`g
`
`14 Claims, 17 Drawing Sheets
`
`40
`735 40|
`
`oo
`
`SENSOR
`
`
`
`
`
`
`sensor|a
`
`42
`
`10
`/
`
`( 53
`
`TRANSMITTER
`PC
`RECEIVER
`RF
`(OPTION)
`
`
`T
`RF
`—
`
`_
`oO
`~~ 50
`
`So52
`
`1
`
`APPLE 1064
`Apple v. Masimo
`IPR2022-01291
`
`APPLE 1064
`Apple v. Masimo
`IPR2022-01291
`
`1
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 1 of 17
`
`US 7,650,176 B2
`
`
`
`22
`
`SIGNAL
`
`FIG.2
`PRIOR ART
`
`2
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 2 of 17
`
`US 7,650,176 B2
`
`FIG.3A
`
`FIG.38BPRIORART
`
`MS
`
`0.9MS
`
`ASIG 0.1%
`
`VAC
`
`3
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 3 of 17
`
`US 7,650,176 B2
`
`
`
`FIG.4
`
`4
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 4 of 17
`
`US 7,650,176 B2
`
`FIG.OB
`FIG.OA
`
`5
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 5 of 17
`
`US 7,650,176 B2
`
`CS0S( 4OSN3S
`
`so
`
`
`
`
`
`6
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 6 of 17
`
`US 7,650,176 B2
`
`62
`
`64
`
`
`
`
`
`
`MEASURE
`DETECTED
`SIGNAL
`
`DC SIGNAL
`COMPONENT
`
`
`
`
` CALCULATE
`66
`
`
`
`PERFORM
`
`CALCULATION ~~
`OXIMETRY
`
`
`
`
`
`
`REMOVE DC SIGNAL
`70
`COMPONENT BY
`
`
`REFERENCE SHIFT —
`
`
`RECEIVE AC
`AND AMPLIFY a
`SIGNAL COMPONENT
`
`72
`
`74
`
`FIG.’
`
`7
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 7 of 17
`
`US 7,650,176 B2
`
`G8Old
`
`QV19S$70089013Ss7008x”“/QLQL
`
`ome)ful
`
`
` /oleladlewolreiluale~\
`
`
`slilaloSilale!ayaa====
`
`28.O8
`
`
`
`wae.SNSfe||||OauNVYINI
`
`
`
`V8Old
`
`
`
`SW9'L
`
`8
`
`
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 8 of 17
`
`US 7,650,176 B2
`
`
`
`
`
`
`
`FIG. 11
`
`9
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 9 of 17
`
`US 7,650,176 B2
`
`
`
`Fig 12A
`
`10
`
`10
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 10 of 17
`
`US 7,650,176 B2
`
`
`
`04|
`
`06{
`
`Figi2B
`
`11
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 11 of 17
`
`US 7,650,176 B2
`
`120
`
`122
`
`124
`
`
`
`
`126
`
`“
`
`
`
`
`
`
`12
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 12 of 17
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`UY
`
`
`
`US 7,650,176 B2
`
`“Lo
`
`“
`
`
` 140
`
`
` Y
`
`1 6
`4
`
`a
`
`a
`a
`Lo
`ox.
`J £3
`Be
`
`Z
`
`o
`
`4
`
`a
`
`a“
`
`v
`
`13
`
`13
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 13 of 17
`
`US 7,650,176 B2
`
`160
`
`168
`
`164
`Fig 15A 166
`
`169
`
`NON
`
`Fig 15B
`
`14
`
`14
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 14 of 17
`
`US 7,650,176 B2
`
`.172
`
`170
`
`15
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 15 of 17
`
`US 7,650,176 B2
`
`2
`
`184
`
`188
`
`
`
`
`182
`
`186
`
`190
`
`Figi6B
`
`16
`
`16
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 16 of 17
`
`US 7,650,176 B2
`
`
`
`
`
`
`
`
`
`214
`206
`
`
`
`
`
`
`
`
`208
`210
`
`212
`
`
`
`17
`
`

`

`U.S. Patent
`
`Jan. 19, 2010
`
`Sheet 17 of 17
`
`US 7,650,176 B2
`
`228
`
`228
`
`226
`
`18
`
`

`

`US 7,650,176 B2
`
`1
`PHYSIOLOGICAL STRESS DETECTOR
`DEVICE AND SYSTEM
`
`CROSS REFERENCE TO RELATED
`APPLICATIONS
`
`This application is a continuation of U.S. application Ser.
`No. 10/390,169, filed Mar. 18, 2003, entitled “Physiological
`Stress Detector Device and System” now U.S. Pat. No. 7,171,
`251, which is a continuation in part application of U.S. appli-
`cation Ser. No. 09/147,683,
`filed Feb. 1, 2000, entitled
`“Physiological Stress Detector Device and System”, now
`USS. Pat. No. 6,553,242, both of which are incorporated
`herein by reference in their entirety.
`
`FIELD OF THE INVENTION
`
`The present inventionrelates to instrumentsthat operate on
`the principle of pulse oximetry, in particular, to non-invasive
`hemoglobin saturation detectors and methods, and may be
`generally applied to other electro-optical methods of measur-
`ing blood constituents.
`
`BACKGROUND OF THE INVENTION
`
`Electro-optical measurement of blood characteristics has
`been found to be useful in many areas of blood constituent
`diagnostics, such as glucoselevels, oxygen saturation, hema-
`tocrit, billirubin and others. This method is advantageous in
`that it can be performedin a non-invasive fashion. In particu-
`lar, much research has been done on oximetry, a way of
`measuring oxygen saturation in the blood, as an early indica-
`tor of respiratory distress.
`Infants duringthefirst year oflife are susceptible to breath-
`ing disturbances (apnea) and respiratory distress. Sudden
`Infant Death Syndrome (SIDS) is a medical condition in
`which an infant enters respiratory distress and stops breath-
`ing, leadingto the death of the infant. Although the cause and
`warning signs of SIDSare not clear, it has been shown that
`early detection of respiratory distress can provide the time to
`administer the aid necessary to prevent death.
`Manytypes of baby monitors are currently available, from
`simple motion detectors to complicated systems which
`stream oxygen enriched air into the infant’s environment.
`Some ofthe more accepted monitoring methods include chest
`motion monitors, carbon dioxide level monitors and heart rate
`(pulse) monitors. Unfortunately these methods often do not
`give the advance warning necessary for the caregivers to
`administer aid. In addition, these monitors are administered
`by attaching a series of straps and cords, which are cumber-
`someto use and present a strangulationrisk.
`The chest motion monitor gives no warning when the
`breathing patterns becomeirregular or when hyperventilation
`is occurring, since the chest continues to move. Distress is
`only noted once the chest motion has ceased at which point
`there may only be a slight chance of resuscitation without
`brain damage. In addition these devices are knownto have a
`high level of “false alarms”as they have no waytodistinguish
`betweenthe lapses in breathing which are normalfor an infant
`(up to 20 seconds) and respiratory distress. These devices can
`cause excessive anxiety for the caregivers or cause them to
`ignore a signal, whichis true after responding repeatedly to
`false alarms.
`
`Among other symptoms, SIDS causes an irregular heart-
`beat, resulting eventually in the cessation of heartbeat with
`the death ofthe infant. There are some instruments, which use
`the EKGprinciple to monitor this clinical phenomenon.This
`
`2
`is a limited methodthat has a very highrate of false positives
`since the monitors have inadequate algorithms to determine
`what is a SIDS event. Obviously, this is not a convenient
`method, nor is it desirable to have the infant constantly
`hooked up to an EKG monitor.
`In light of these disadvantages a better methodto useis a
`form ofelectro-optical measurement, such as pulse oximetry,
`which is a well-developed art. This method uses the differ-
`ence in the absorption properties of oxyhemoglobin and
`deoxyhemoglobin to measure blood oxygen saturation in
`arterial blood. The oximeter passes light, usually red and
`infrared, through the bodytissue and uses a photo detector to
`sense the absorption of light by the tissue. By measuring
`oxygen levels in the blood, one is able to detect respiratory
`distress at its onset giving sufficiently early warning to allow
`aid to be administered as necessary.
`Twotypes of pulse oximetry are known. Until now, the
`more commonly used type has been transmission oximetry in
`which two or more wavelengths of light are transmitted
`through the tissue at a point where blood perfuses the tissue
`(i.e. a finger or earlobe) and a photo detector senses the
`absorption oflight from the other side of the appendage. The
`light sources and sensors are mounted ina clip that attaches to
`the appendage anddelivers data by cable to a processor. These
`clips are uncomfortable to wear for extended periods oftime,
`as they mustbe tight enoughto exclude externallight sources.
`Additionally, the tightness of the clips can cause hematoma.
`Use of these clips is limited to the extremities where the
`geometry of the appendagesis such that they can accommo-
`date a clip of this type. The clip must be designedspecifically
`for one appendage and cannot be used on a different one.
`Children are too active to wear these clips and consequently
`the accuracy ofthe reading suffers.
`In another form of transmission oximetry, the light source
`and detector are placed on a ribbon, often made of rubber,
`which is wrapped around the appendagesothatthe source is
`on oneside andthe detector is on the other. This is commonly
`used with children. In this method error is high because
`movement can cause the detector to become misaligned with
`the light source.
`It would be preferable to be able to use the other type of
`pulse oximetry knownasreflective, or backscattering, oxim-
`etry, in which the light sources and light detector are placed
`side by side on the sametissue surface. Whenthe light sources
`and detector can be placed on the tissue surface without
`necessitating a clip they can be applied to large surfaces such
`as the head, wrist or foot. In cases such as shock, when the
`blood is centralized away from the limbs, this is the way
`meaningful results can be obtained.
`One difficulty in reflective oximetry is in adjusting the
`separation betweenthe light source and the detector such that
`the desired variable signal component (AC) received is
`strong, since it is in the alternating current that information is
`received. The challenge is to separate the shunted, or coupled,
`signal which is the direct current (DC) signal component
`representing infiltration of external light from the AC signal
`bearing the desired information. This DC signal does not
`provide powerful information. If the DC signal componentis
`not separated completely, when the AC signal is amplified any
`remaining DC componentwill be amplified with it, corrupt-
`ing the results. Separating out the signal componentsis not a
`simple matter since the AC signal componentis only 0.1% to
`1% ofthe total reflected light received by the detector. Many
`complicated solutions to this problem have been proposed.
`Ifthe light source and detector are moved furtherapart,this
`reduces the shunting problem (DC), however, it also weakens
`the already weakAC signal component. Ifthe light source and
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`19
`
`19
`
`

`

`US 7,650,176 B2
`
`3
`detector are moved close together to increase the signal, the
`shunting (DC) will overpowerthe desired signal (AC).
`Takataniet al., in U.S. Pat. No. 4,867,557, Hiraoet al., in
`USS. Pat. No. 5,057,695 and Mannheimer, in U.S. Pat. No.
`5,524,617 all disclose reflective oximeters that require mul-
`tiple emitters or detectors in order to better calculate the
`signal.
`A numberof attempts have been madeto filter out the DC
`electronically (see Mendelsonet al., in U.S. Pat. No. 5,277,
`181). These methods are very sensitive to changes in signal
`level. The AC remaining after the filtering often contains a
`small portion of DC, which upon amplification of the AC
`becomes amplified as well, resulting in inaccurate readings.
`Therefore, this method is only useful in cases where the signal
`is strong and uniform.
`Israeli patents 114082 and 114080 disclose a sensor
`designed to overcomethe shunting problem by using optical
`fibers to filter out the undesired light. This is a complicated
`and expensive solution to the problem that requires a high
`level oftechnical skill to produce.In addition,it is ineffectual
`when the AC signal is relatively weak.
`As can be seen from the above discussion, the prior art
`methods of addressing the AC/DCsignal separation problem
`in reflective oximetry techniques are complicated and expen-
`sive. Therefore, it would be desirable to provide a simple, low
`cost and effective method for achieving accurate reflective or
`transmitted oximetry detection of respiratory stress.
`
`SUMMARYOF THE INVENTION
`
`Accordingly,it is the broad object of the present invention
`to overcome the problems of separating the shunted light
`from the signal in order to provide a physiological stress
`detector that achieves accurate readings.
`A general object of this invention is to overcomethe prob-
`lemsof separating the shunted light from the signal in order to
`provide a respiratory stress detector that achieves accurate
`pulse oximetry readings for respiratory stress applications.
`Thepresent invention discloses a small, independent, sen-
`sor, for invasive and non-invasive applications unencumbered
`by cables or wires, which is capable of being attached to
`different body parts, to comfortably and accurately monitor
`blood constituent levels and the pulse ofaninfant or any other
`living organism. The apparatus may be applied to any part of
`the body without prior calibration. Accurate readings ofblood
`constituent levels are obtained using the inventive method in
`which a precise separation of the AC and DC signal compo-
`nents has been achieved, allowing each signal component to
`be amplified separately. In order to accomplish this precise
`separation, the signal components are separated by a novel
`signal processing technique.
`The inventive sensor may be adapted for many health-
`monitoring situations including infant monitoring for SIDS,
`fetal monitoring,etc.
`In an embodiment adapted for SIDS, the sensoris designed
`to apply reflective oximetry techniques, so as to comfortably
`and accurately monitor the arterial oxygen levels and the
`pulse of an infant or any other living organism prone to
`respiratory distress. This monitor is equipped with a proces-
`sor capable of determining the need for an alarm and capable
`of signaling a distress signal to further alert to a crisis.
`In another embodiment, in addition to the alarm being
`generated from the sensoritself, readings will be radio-trans-
`mitted to a base station, possibly at a nurse’s station, to allow
`monitoring ofthe reading, and another alarm will be activated
`from the base station when the readings are outside of the
`accepted range.
`
`4
`In another embodiment, the apparatus is mounted in a
`sock-type mounting such that
`the apparatus is properly
`applied when the sock is put on in the usual fashion. In
`addition, the sock-type apparatus blocks entrance of external
`light to the area of the sensor apparatus.
`In yet another embodiment, the apparatus is mounted on a
`ribbon-type mounting such that the apparatus is properly
`applied whenthe ribbon is tied aroundthe heador other body
`part. In addition, the width of the ribbon is such that it will
`block entrance of external light to the area of the sensor
`apparatus. Additionally, the ribbon may be of dark color,
`whichalso blocks entrance of external light to the area of the
`sensor apparatus.
`In yet another embodiment, the apparatus is mounted on a
`bracelet-type mounting such that the apparatus is properly
`applied when the bracelet is fastened to the wrist or other
`bodypart. In addition, the width of the braceletis such that it
`blocks entrance of external light to the area of the sensor
`apparatus. Additionally, the bracelet may be of dark color,
`whichalso blocks entrance of external light to the area of the
`sensor apparatus.
`There is therefore provided, in accordance with a preferred
`embodimentof the present invention, a non-invasive device
`for measurementofbloodsaturation and heart pulse rate of an
`organ. The device includes a housing unit havingat least one
`light source, providing light directed towardthe surface ofthe
`organ, the light being reflected from the organ, a sensor device
`spaced apart from the light source and being sensitive to
`intensity levels of the reflected light for producing intensity
`signals in accordance therewith and a processing unit for
`processing the intensity signals received from the sensor
`device and for producing output signals.
`Furthermore,
`in accordance with another preferred
`embodiment of the present invention,
`the device further
`includes a transmitter configured to transmit the output sig-
`nals to areceiver at a remote location. The device may further
`include a display unit for displaying the output signals.
`Additionally, there is also provided, in accordance with a
`preferred embodimentofthe present invention, a monitoring
`system which includes a non-invasive device for measure-
`ment of blood saturation and heart pulse rate, and a receiver
`configured to indicate an alert when the blood saturation or
`heart pulse rate falls outside of a pre-determined range.
`The non-invasive device may include a housing unit con-
`figured to fit a wrist or ankle, including a baby. The housing
`unit includesat least onelight source, providing light directed
`toward the surface of the organ, the light being reflected from
`the organ, a sensor device spaced apart from the light source
`and being sensitive to intensity levels ofthe reflected light for
`producing intensity signals in accordance therewith, a pro-
`cessing unit for processing the intensity signals received from
`the sensor device and for producing output signals and a
`transmitter configured to transmit the output signals to a
`receiver at a remote location. The processing unit may be
`integrated with the sensor device.
`Furthermore,
`in accordance with another preferred
`embodimentof the present invention, the display unit may be
`configured in the shape of a watch. The display unit may
`include a memory storage unit for storing the output signals.
`Furthermore, the transmitter may be integrated with the dis-
`play unit.
`in accordance with another preferred
`Furthermore,
`embodiment of the present invention,
`the device further
`includesan alerter configured to transmit an alert signal. The
`alerter may be configured to transmit a signal whenever the
`blood saturation or heart pulse rate falls outside of a pre-
`determined range.
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`20
`
`20
`
`

`

`US 7,650,176 B2
`
`5
`Thealerter may also be configured to transmit data signals
`includingat least the blood saturation or heart pulserate.
`Furthermore,
`in accordance with another preferred
`embodimentofthe presentinvention, the housing unit may be
`configured to be attachable to a head covering, such as a cap,
`a hat and a bandanna, for example.
`Furthermore,
`in accordance with another preferred
`embodimentofthe presentinvention, the housing unit may be
`configured to adhere to the surface of the skin.
`Furthermore,
`in accordance with another preferred
`embodimentofthe presentinvention, the housing unit may be
`configured to be integrated within a protective mask, includ-
`ing a search and rescue mask, gas mask, anti biological and
`chemical mask.
`
`in accordance with another preferred
`Furthermore,
`embodimentof the present invention, the device may further
`include a display or indication unit. The displayor indication
`unit may includean indication ofthe well being ofthe wearer.
`Furthermore,
`in accordance with another preferred
`embodimentofthe present invention, the receiving deviceat
`the remote location may be a personaldigital assistant (PDA).
`Furthermore,
`in accordance with another preferred
`embodimentofthe presentinvention, the housing unit may be
`configured to receive a human digit such asa finger.
`Furthermore,
`in accordance with another preferred
`embodimentofthe presentinvention, the housing unit may be
`configured in the shape of a pen and the sensor device is
`located on the external face of the pen, thereby allowing the
`housing unit to be disposed proximate to the skin.
`Furthermore,
`in accordance with another preferred
`embodimentofthe present invention, the processor develops
`a control signal when the adjustably-determined second gain
`amplification factor is established in the second stage, the
`signal is measured and the control signal shuts off the light
`source.
`
`in accordance with another preferred
`Furthermore,
`embodimentofthe present invention, the control signal con-
`serves energy by reducing the operational duty cycle of the
`light source.
`in accordance with another preferred
`Furthermore,
`embodimentofthe present invention,the first and second gain
`amplification factors are determined by the processor in an
`iterative process by adjustably setting a gain amplification
`factor and measuring a dynamic voltage range of the output
`signals to determine if the voltage range falls within a prede-
`termined windowestablished by the processor.
`Furthermore,
`in accordance with another preferred
`embodimentof the present invention, the light source com-
`prises a single light-emitting unit capable of controllably
`providing light having a wavelength range selected from at
`least a first wavelength range and a second wavelength range.
`Thefirst wavelength range is at least partially different from
`the second wavelength range. The single light-emitting unit
`can be switched from emitting light within the first wave-
`length range to emitting light within the second wavelength
`range.
`in accordance with another preferred
`Furthermore,
`embodiment of the present
`invention,
`the light source
`includesat leasta first light-emitting unit capable of control-
`lably emitting light having a first wavelength range and a
`second light-emitting unit capable of controllably emitting
`light having a second wavelength range.
`The first wavelength range is at least partially different
`from the second wavelength range.
`Furthermore,
`in accordance with another preferred
`embodimentof the present invention, the light source pro-
`vides light having wavelengths in the red andinfrared ranges.
`
`6
`Other features and advantages ofthe invention will become
`apparent from the following drawings and description.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`For a better understanding, the invention will now be
`described, by way of example only, with reference to the
`accompanying drawings in which like numerals designate
`like components throughout the application, and in which:
`FIG. 1 is a schematic layout diagram of a physiological
`stress detector device, constructed and operated in accor-
`dance with the principles of the present invention;
`FIG. 2 is an electronic schematic diagram of a prior art
`signal processing technique, for use with the device ofFIG. 1;
`FIGS. 3a-3b show, respectively, a prior art signal wave-
`form representing emitted and receivedlight;
`FIGS. 4 and 5a-b show, respectively, arrangements for
`wearing the device of FIG. 1 on the bodyof aninfant ona leg,
`foot or head;
`FIG.6 is an electronic block diagram showingthe signal
`processing componentsofthe device ofthe present invention;
`FIG. 7 is an algorithm of a signal processing technique
`performed in accordance with the principles of the present
`invention;
`FIGS. 8a-6 are, respectively, signal waveformsrepresent-
`ing emitted red andinfrared light used in the device of FIG.1;
`FIG. 9 is a timing diagram applied in an automatic gain
`adjustment procedure during signal processing;
`FIG. 10 is a schematic illustration ofa device for determin-
`ing blood flow velocity in accordance with another preferred
`embodimentof the present invention;
`FIG. 11 is a schematic graph useful in understanding the
`methodof determining bloodflow velocity used by the device
`of FIG.10;
`FIGS. 12a-12c are schematic illustrations of an exemplary
`application of a device for determining blood saturation and
`heart pulse rate according to an embodimentof the invention;
`FIGS. 13a-136 are schematicillustrations of an exemplary
`application of a device for determining blood saturation and
`heart pulse rate according to another embodiment of the
`invention;
`FIGS. 14a-14c are schematicillustrations of an exemplary
`application of a device for determining blood saturation and
`heart pulse rate according to another embodiment of the
`invention;
`FIGS. 15a-15c are schematic illustrations of an exemplary
`application of a device for determining blood saturation and
`heart pulse rate according to another embodiment of the
`invention;
`FIGS. 16a-16c are schematicillustrations of a monitoring
`system according to an embodimentofthe invention;
`FIGS. 17a-176 are schematicillustrations of a monitoring
`system according to another embodiment of the invention,
`and
`
`FIGS. 18a-18c are schematicillustrations of an exemplary
`application of a device for determining blood saturation and
`heart pulse rate according to another embodiment of the
`invention.
`
`DETAILED DESCRIPTION OF PREFERRED
`EMBODIMENTS
`
`The following description presents a detailed construction
`of a physiological stress detector device adapted for use in
`monitoring arterial oxygen levels. In this particular applica-
`tion,the reflective oximetry methoduseslight wavelengths in
`the red and infrared ranges, since these are most suitable for
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`21
`
`21
`
`

`

`US 7,650,176 B2
`
`7
`detecting oxygensaturation in hemoglobin. As will be under-
`stood by those skilled in the art, particular design features
`used for this application can be varied for different applica-
`tions. For example, in an application for monitoring jaundice
`through billirubin levels, other suitable, light wavelengths
`would be used. Therefore, the light wavelengths discussed in
`the following description are not intendedto limit the scope of
`the present invention, and are to be understood as pertaining
`to the subject example only.
`there is shown a preferred
`Referring now to FIG. 1,
`embodimentofa physiological stress detector device 10 con-
`structed and operated in accordance with theprinciples of the
`present
`invention. Device 10 comprises a housing 12
`arranged for placement in close proximity to a skin surface
`14. Housing 12 maybe providedas a casing enclosing a light
`source 16 emitting two wavelengths, red and infrared, and a
`photo detector 18 spaced apart from the light source 16.
`Device 10 is designed to be operated such that whenlight
`source 16 emits light of a red or infrared wavelength,the light
`penetrates skin tissue (arrow A) and a portion ofthe lightis
`reflected backto light detector 18, along a path defined by line
`20.
`
`8
`used to amplify the variable signal portion. The DC signal
`componentofthe received light, which doesnot pass through
`blocking capacitor 24, forms the inputof, and is amplified by
`operational amplifier 28.
`Asillustrated in FIGS. 3a-30, the signal waveform repre-
`senting the emitted light, (FIG. 3a) is substantially repro-
`duced as a received signal waveform (FIG. 35). Even after
`filtering by signal processingfilter 22, the AC signal compo-
`nent remaining ASIGis only a small portion ofalargersignal,
`which has been amplified by operational amplifier 26, and
`therefore dominates the variable signal portion. Thus, this
`methodof signal separation results in inaccurate readings of
`reflected light, and cannot provide accurate information in
`oximetry measurements.
`In FIGS. 4 and 5a-6 there are shownalternative configu-
`rations of device 10, respectively, provided in a foot bracelet
`30, a sock 32 worn around the ankle, and a ribbon 34 worn
`around the head. In each arrangement, casing 12 is designed
`to be held tightly against skin surface 14 to reduce the amount
`of stray light entering into the optical path between light
`source 16 and detector 18.
`
`20
`
`Preferably, the casing 12 is made from a material opaque to
`light in the relevant spectral range to which the detector 18 is
`Thelight source 16 may be implementedas a single com-
`sensitive, such as an opaqueplastic material, metal orthelike.
`ponent, which can controllably emits red or infrared light. A
`The foot bracelet 30, the sock 32 and the ribbon 34 may be
`non-limiting example of the light source 16 is the selectable
`made of a material, which allows the casing 12 to be tightly
`wavelength light emitting diode (LED) component model
`pressed against the skin. This material may be a flexible
`L122R6IR880, or for pediatric or prematurely born baby
`
`applications the component model SML12R6IR880, both material such asaflexible fabric. The material may also be a
`components are commercially available from Ledtronics,
`porous or woven materialto prevent excessive perspiration of
`the skin thereunder.
`CA, U.S.A. However, The light source 16 may also include
`two separate suitable light sources. For example, the light
`source 16 may include two separate light sources (not shown)
`such as an LED emitting red light and another different LED
`emitting infrared light.
`Tt is noted that, while, preferably, the light source 16
`includes one or more LEDs emitting in the suitable red and
`infrared ranges, other light sources may be used such as
`incandescent lamps in combination with suitable optical fil-
`ters, various types of gas discharge or arc lamps, with or
`withoutopticalfilters, diode laser devices, or any other.
`For the pulse-oximetry application the light detector 18
`may be a photodiode, such as the model BPW34 photodiode,
`or for pediatric and premature born babies the model
`BPW34S photodiode, both commercially available from
`Siemens Semiconductor Group, Germany. However, many
`other types of photo-detecting devices may be used such as
`resistive photocells, or any other type of photo detector,
`whichhasthe requiredsensitivity at the wavelengths, used for
`the specific application of the device 10.
`It is noted that the device 10 of FIG. 1 also includes further
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`electronic components (not shown in FIG. 1), which are dis-
`closed in detail hereinbelow (as best seen in FIG.6).
`Asdescribedin the backgroundofthe invention, the device
`10 employs non-invasive reflective oximetry techniques to
`provide measurementof blood characteristics useful in diag-
`nostic procedures and detection of physiological stress. As
`mentioned, one difficulty in reflective oximetry is in adjusting
`the separation between light source 16 and detector 18 such
`that the desired signal received by light detector 18 is strong
`and not affected by shunted, or coupled, light from source 16.
`FIGS. 2 and 3a-36 illustrate this problem and the priorart
`techniques currently availablefor its solution.
`In FIG.2 there is shown an electronic schematic diagram of
`a signal processing filter 22 used to separate the variable
`signal (AC) component of received light from the shunted
`(DC), or coupled, light. The separation is achieved by a block-
`ing capacitor 24 on the input of an operational amplifier 26
`
`55
`
`60
`
`65
`
`22
`
`Referring now to FIG. 6, there is shown an electronic
`schematic block diagram of device 10. Device 10 comprises
`a sensor 35 incorporating light source 16 and detector 18. The
`sensor 35 mayalso include a preamplifier circuit (not shown)
`for amplifying the output signals of the detector 18 and feed-
`ing the amplified signals to the processing unit 40. It will be
`appreciated by those skilled in the art that the numbersoflight
`sources and detectors can be varied while keeping the same
`processing method.In addition, device 10 comprisesa signal
`processing unit 40 including a pair of operational amplifiers
`A1 andA2, an analog to digital converter 42, a central pro-
`cessing unit (CPU)/controller 44, and a digital to analog
`converter 46. In critical applications, such as SIDS, when
`there exists a need for emergencyfirst aid availability, when
`CPU 44 has determinedthat the value obtainedis not within
`
`the acceptable range an outputsignal47is fed to an alarm unit
`48 causing an alarm to b