United States Patent
`US 7,107,088 B2
`(10) Patent No.:
`(12)
`Aceti
`(45) Date of Patent:
`Sep. 12, 2006
`
`
`US007107088B2
`
`(54) PULSE OXIMETRY METHODS AND
`APPARATUS FOR USE WITHIN AN
`AUDITORY CANAL
`
`(75)
`
`Inventor:
`
`John Gregory Aceti, West Windsor, NJ
`(US)
`
`(73) Assignee: Sarnoff Corporation, Princeton, NJ
`(US)
`
`(*) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`US.C.154(b) by 190 days.
`.
`No.:
`5
`(21) Appl. No.: 10/847,678
`
`(22)
`
`Filed:
`
`May 17, 2004
`
`(65)
`
`Prior Publication Data
`US 2005/0049471 Al
`Mar. 3, 2005
`
`(51)
`
`Related U.S. Application Data
`(60) povisional application No. 60/497,890, filed onAug.
`?
`:
`Int. Cl.
`AG6IB 5/00
`(2006.01)
`AGIB 5/02
`(2006.01)
`(52) U.S. Cl
`600/340: 600/502
`(58) Field of ClassificationSearch
`;600/310
`600/322. 323.340. 344. 500 502. 549
`See application file for com: letesearch histo
`,
`P
`y:
`PP
`References Cited
`U.S. PATENT DOCUMENTS
`
`(56)
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`11/1994 Hall et al.
`
`(Continued)
`
`FOREIGN PATENT DOCUMENTS
`2210 168 A
`1/1989
`
`GB
`
`(Continued)
`Primary Examiner—Eric F. Winakur
`(74) Attorney, Agent, or Firm—Lowenstein Sandler, PC
`57
`ABSTRACT
`67)
`:
`:
`Methods and apparatus for detecting oxygen saturation
`levels in blood from within an auditory canal of a living
`being proximal to a tympanic membraneare disclosed. The
`auditory canal is lined with tissue and includes a proximal
`bend and a distal bend located between the proximal bend
`and the tympanic membrane. Oxygen levels are detected by
`emitting one or more wavelengths of light
`into a first
`position on the tissue of the auditory canal in a first region
`defined by the distal bend and the tympanic membrane. The
`wavelengths of light are then sensed at a second position on
`the tissue of the auditory canal in the first region. A blood
`oxygen saturation level and/or pulse rate is then calculated
`responsive to intensity information corresponding to the
`wavelengths of light detected at the second position.
`
`18 Claims, 6 Drawing Sheets
`
`212
`
`200
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`f—
`
`
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`
`
`Apple Inc.
`APL1153
`U.S. Patent No. 8,942,776
`
`Apple Inc.
`APL1153
`U.S. Patent No. 8,942,776
`
`001
`
`

`

`US 7,107,088 B2
` Page 2
`
`U.S. PATENT DOCUMENTS
`
`5,469,855 A
`5,626,139 A
`5,673,692 A
`5,812,992 A
`oad A
`6047-205 A
`6053887 A
`6078443 A
`6.078.829 A
`6,080,110 A
`6,115,621 A
`6,205,227 Bl
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`6,289,309 B1
`
`11/1995 Pompeiet al.
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`i900 nevis otal
`42000 ae
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`§/2003 Casscells, III et al.
`
`FOREIGN PATENT DOCUMENTS
`
`GB
`WO
`Wo
`
`2 302 945 A
`WO 97/09927
`WO 01/17109 Al
`
`5/1997
`3/1997
`3/2001
`
`002
`
`002
`
`

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`U.S. Patent
`
`Sep. 12, 2006
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`Sheet 1 of 6
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`US 7,107,088 B2
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`102
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`wetae a ee _
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`A)ot
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`FIG. 1
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`003
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`003
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`U.S. Patent
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`Sep. 12, 2006
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`Sheet 2 of 6
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`US 7,107,088 B2
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`002
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`avec
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`SFZZEz
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`éSid
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`004
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`004
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`U.S. Patent
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`Sep. 12, 2006
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`Sheet 3 of6
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`US 7,107,088 B2
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`
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`FIG. 2A
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`005
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`005
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`U.S. Patent
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`Sep. 12, 2006
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`Sheet 4 of6
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`US 7,107,088 B2
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`N
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`FIG.3
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`210
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`006
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`006
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`U.S. Patent
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`Sep. 12, 2006
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`Sheet 5 of6
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`US 7,107,088 B2
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`224b
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`226
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`224a
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`FIG. 4A
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`224a
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`224b
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`226
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`224a
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`224b
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`FIG. 4B
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`226
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`FIG. 4C
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`007
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`U.S. Patent
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`Sep. 12, 2006
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`Sheet 6 of6
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`US 7,107,088 B2
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`500
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`Emitlight of at least two wavelengthsintoafirst position on the
`vascular tissue of the auditory canal in a region defiend by the distal
`bend and the tympanic membrane.
`
`of detectedlight.
`
`Detectlight of the at least two wavelengths at a second position on
`the vascular tissue of the auditory canal in the region defined by the
`distal bend and the tympanic membrane.
`
`Calculate oximetry levels responsive to the at least two wavelengths
`
`FIG. 5
`
`008
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`008
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`

`

`US 7,107,088 B2
`
`1
`PULSE OXIMETRY METHODS AND
`APPARATUS FOR USE WITHIN AN
`AUDITORY CANAL
`
`CROSS REFERENCE TO RELATED
`APPLICATION
`
`This application claims the benefit of U.S. Provisional
`Application No. 60/497,890, filed Aug. 25, 2003, the con-
`tents of which are incorporated herein by reference.
`
`FIELD OF THE INVENTION
`
`2
`reference numerals. This emphasizes that, according to
`commonpractice, the various features of the drawings are
`not drawn to scale. On the contrary, the dimensions of the
`various features are arbitrarily expanded or reduced for
`clarity. When a plurality of similar elements are present, a
`single reference numeral maybe assignedto the plurality of
`similar elements with a small letter designation referring to
`specific elements. When referring to the elements collec-
`tively or to a non-specific one or more of the elements, the
`small letter designation may be dropped. Included in the
`drawings are the following figures:
`FIG. 1 is a cross sectional anatomical illustration of an
`
`invention relates to the field of medical
`The present
`devices and, more particularly, to noninvasive pulse oxim-
`etry methods and apparatus for use inside an auditory canal
`of a living being.
`
`BACKGROUND OF THE INVENTION
`
`auditory canal and surrounding structure;
`FIG.2 is a cross-sectional view of an exemplary oximetry
`sensor in accordance with the present invention;
`FIG.2A is a perspective view of an alternative exemplary
`oximetry sensor in accordance with the present invention;
`FIG.3 is a surface view of a portion of an exemplary outer
`surface of the oximetry sensor of FIG.2;
`FIGS. 4A, 4B, and 4C are cross-sectional views of
`An oximeter calculates blood oxygen saturation levels
`exemplary portions of the oximetry sensor; and
`within a living being from the different rates at which
`FIG.5is a flow chart of exemplary steps for determining
`oxygenated hemoglobin (oxyhemoglobin) and reduced
`oximetry levels in accordance with the present invention.
`hemoglobin (deoxyhemoglobin) within vascular tissue of
`the living being absorb light of different wavelengths. Typi-
`cally, two wavelengths of light are used where one wave-
`length is much less sensitive to blood oxygen saturation
`levels than the other. The wavelength of light that is less
`sensitive to oxygen saturation levels serves as a constant
`against which the wavelength of light that is more sensitive
`to oxygen saturation levels is compared in order to calculate
`blood oxygen saturation levels.
`The measurement of oxygen saturation levels (“oxim-
`etry’) is a critical physiologic measurementforcritical care
`patients. Presently, sensors for use with oximeters to mea-
`sure oxygen saturation levels in vascular tissue are designed
`for placement on a finger, ear lobe, foot, or in an outer
`portion of the auditory canal. These sensors are subject to
`motion artifacts that may result in inaccurate measurements.
`Accordingly, improved oximetry methods and apparatus are
`needed that are not subject to this limitation. The present
`invention addresses this need among others.
`
`SUMMARY OF THE INVENTION
`
`The present invention is embodied in methods and appa-
`ratus for detecting oxygen saturation levels in blood from
`within an auditory canal of a living being proximal to a
`tympanic membrane. The auditory canalis lined with tissue
`and includes a proximal bend and a distal bend located
`between the proximal bend and the tympanic membrane.
`Oxygen levels are measured by emitting one or more
`wavelengths of light into a first position on the tissue of the
`auditory canal in a first region defined by the distal bend and
`the tympanic membrane; sensing the wavelengths oflight at
`a second position on the tissue of the auditory canal in the
`first region, the second position being spaced from thefirst
`position; and calculating at least one of (1) a blood oxygen
`saturation level and (ii) a pulse rate responsive to intensity
`information corresponding to the wavelengths of light
`detected at the second position.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The invention is best understood from the following
`detailed description when read in connection with the
`accompanying drawings, with like elements having the same
`
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`DETAILED DESCRIPTION OF THE
`INVENTION
`
`FIG. 1 show a cross-sectional anatomical view of an
`
`auditory canal 100 in the transverse plane of a portion 102
`of a head. The auditory canal 100 is generally S-shaped and
`can be described as having three regions. A first region 20 is
`the medial concha cavity, which is surrounded by cartilagi-
`noustissue 22. A second region 23, which is separated from
`the first region 20 bya first bend 30 (the “proximal bend”),
`is also surrounded by cartilaginous tissue 22. A third region
`25, which is separated from the second region 23 by a
`second bend 31 (the “distal bend”), defines thefinal auditory
`canal region near the tympanic membrane 26 and is sur-
`rounded by dense bonytissue 27.
`Vasculartissue 28 covering the first and second regions 20
`and 23 is relatively thick and has a well developed subcu-
`taneous layer that allows some expansion to occur.
`In
`contrast, vascular tissue 29 covering the third region 25 is
`relatively thin and, thus, little or no tolerance for expansion
`exists in this region.
`Mandibular motion associated with activities such as
`talking, chewing, yawning, and biting deformsthefirst and
`second regions 20 and 23 of the auditory canal 100. This
`deformation is generally caused by the asymmetric stresses
`from the actions of the mandibular condyle 33 on neighbor-
`ing cartilaginous tissue 22. These deformations haveradial
`components, e.g. constrictions, and axial components, i.e.
`inward and outward motion, which mayresult in motion
`artifacts in known oximetry sensors positioned within the
`first or second regions 20 and 23. Thethird region 25, which
`is surrounded by bony tissue 27,
`is less susceptible to
`deformation due to mandibular motion. Additional details
`regarding the auditory canal may be found in U.S. Pat. No.
`5,701,348, which is incorporated fully herein by reference.
`FIG.2 depicts an exemplary oximetry sensor 200 and will
`be described with reference to the auditory canal 100 of FIG.
`1. The oximetry sensor 200 is configured to measure oxygen
`saturation levels in the vascular tissue 29 within the third
`
`65
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`region 25 of the auditory canal 100. A first portion 202 of the
`oximetry sensor 200 is configured for placement
`in the
`second region 23 of the auditory canal 100, i.e., between the
`first bend 30 and the second bend 31. Thefirst portion 202
`009
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`US 7,107,088 B2
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`3
`includes a distal end 204 that extends toward the tympanic
`membrane 26 when the oximetry sensor 200 is positioned
`within the auditory canal 100. In an exemplary embodiment,
`the first portion 202 includes an outer surface (shell) 206 that
`is relatively rigid and shaped to conform to the contours of
`the second region 23.
`In an exemplary embodiment, the outer surface 206 of the
`first portion 202 is substantially smooth andthefirst portion
`202 further includes a hollow bodyportion 208 that extends
`from the distal end 204 to an outer end 210 that is substan-
`
`tially opposite the distal end 204. The hollow body portion
`208 defines an elongated passage 209 that extends between
`the outer end 210 and the distal end 204 ofthe first portion
`202 for communication of acoustic signals throughthefirst
`portion 202. The hollow body portion 208 may be config-
`ured such that light is not passed by the hollow passage to
`the vascular tissue 29 in the third region 25.
`In an alternative exemplary embodiment, the outer sur-
`face 206 of the first portion 202 includes one or more
`protrusions (fins, bumps, etc.) that form channels extending
`from the outer end 210 to the distal end 204 of the first
`
`portion 202 in addition to, or instead of, the hollow body
`portion 208. FIG. 3 represents an exemplary portion 300 of
`the outer surface 206 (FIG. 2) between the outer end 210 and
`the distal end 204. The exemplary portion 300 includes
`protrusions (represented by a first protrusion 302, a second
`protrusion 304, and a third protrusion 306). The illustrated
`first and second protrusions 302 and 304 define a first
`channel 308 and the second andthird protrusions 304 and
`306 define a second channel 310. The channels 308 and 310
`
`each have a “maze-like” configuration that doubles back on
`itself between the outer end 210 and the distal end 204 to
`allow acoustic signals to pass through the second region 23
`(FIG. 1) to a second portion 212 (FIG. 2) while blocking
`light from reaching the vascular tissue 29 in the third region
`25.
`
`In an exemplary embodiment, the protrusionsare sized to
`comfortably support thefirst portion 202 within the auditory
`canal 100 while allowing air (sound) to flow freely past the
`first portion 202. The protrusions act to centrally hold the
`first portion 202 in the second region 23 of the auditory canal
`100 and comfortably touch the vascular tissue 28 of the
`auditory canal 100. Each protrusion may havea flat surface
`where it contacts the vascular tissue 28 to minimize dis-
`comfort. Although three protrusionsare illustrated, fewer or
`more protrusions may be formed on the outer surface 206.
`Positioning a device within the auditory canal 100 nega-
`tively affect hearing, however, a hole larger than 2 mm,or
`an effective passage(s) having an area equivalent to a2 mm
`hole or larger will substantially pass most low to high audio
`frequencies.
`Referring back to FIG. 2, a second portion 212 of the
`oximetry sensor 200 is configured for placementin the third
`region 25 of the auditory canal 100, i.e., between the second
`bend 31 and the tympanic membrane 26. The second portion
`212 includes optically transparent portions 224 andoptically
`blocking portions 226 for use in measuring oximetry levels
`within the vascular tissue 29 of the third region 25, which is
`described in further detail below. The optically transparent
`portions 224 form channels and/or islands within the opti-
`cally blocking portions 226. An outer surface 214 of the
`second portion 212 is configured to abutat least a portion of
`the vascular tissue 29 lining the auditory canal 100 in the
`third region 25. Due to the dense bonytissue 27 surrounding
`the third region 25, positioning the second portion 212
`within the third region 25 effectively isolates the second
`portion 212 from being directly affected by mandibular
`
`4
`motion, thereby reducing oximetry false alarms associated
`with motion artifacts. Additionally, positioning the second
`portion 212 past the second bend 31 tends to “lock” the
`oximetry sensor 200 in position.
`In an exemplary embodiment, the second portion 212 is
`movably coupledto thefirst portion 202. The second portion
`212 includes a proximal end 216 and a tympanic end 218
`that extends toward the tympanic membrane 26 when the
`oximetry sensor 200 is positioned within the auditory canal
`100. Although positioning the second portion 212 within the
`third region 25 effectively isolates the second portion from
`being directly affected by mandibular motion, the second
`portion 212 may be indirectly affected by mandibular
`motion transferred to the second portion 212 through the
`first portion 202. Movably coupling the second portion 212
`to the first portion 202 reduces the effect of this indirect
`mandibular motion on the second portion 212,
`thereby
`further reducing oximetry measurementfalse alarms due to
`motion artifacts.
`
`In an exemplary embodiment, the second portion 212
`further includes a hollow body portion 220 that defines an
`elongated passage 222 extending between the proximal end
`216 and the tympanic end 218 of the second portion 212.
`The hollow body portion 220 is configured to communicate
`acoustic signals through the second portion 212 between the
`first portion 202 and the tympanic membrane 26. If each of
`the first and second portions 202 and 212 include elongated
`passages (e.g., elongated passages 209 and 222), acoustic
`signals originating from outside the auditory canal 100 may
`pass to the tympanic membrane 26.
`In an exemplary embodiment, the second portion 212 is
`made of a flexible elastomer, which renders the second
`portion 212 movable with respect to the first portion 202.
`The flexible elastomer facilitates the navigation of the
`typical, nominally S-shaped centerline path of the auditory
`canal 100. The second portion 212 may be constructed of a
`low modulus, low durometer material to provide a high level
`of comfort for the user even when it is inserted into the third
`
`region 25 of the auditory canal 100. In addition, the hollow
`body portion 220 may be substantially tubular in shape and
`elongated to permit a continuum of deformations along its
`length so that its axis can conform to the axis of the auditory
`canal in the third region 25.
`In an alternative exemplary embodiment, as depicted in
`FIG. 2A, a mechanical joint 270 may be positioned between
`the first portion 202 and the second portion 212 to render the
`second portion 212 movablerelative to thefirst portion 202.
`Theillustrated mechanical joint 270 includes a ball portion
`272 and a ball receiving portion 274 configured to movably
`engage the ball portion 272. Examples of suitable mechani-
`cal joints may be found in U.S. Pat. No. 6,205,227 to
`Mahoney et
`al.
`titlked PERITYMPANIC HEARING
`INSTRUMENT, which is commonly assigned with the
`present application and incorporated fully herein by refer-
`ence.
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`Referring back to FIG. 2, an emitter 228 is positioned
`within the oximetry sensor 200 to emit light of two or more
`wavelengths from a first optically transparent portion 224a
`of the second portion 212 into a correspondingfirst position
`of the vascular tissue 29 when the oximetry sensor 200 is
`positioned within the auditory canal 100. The illustrated
`emitter 228 includes a first light source 230, a first light
`channel 232, a second light source 234, and a secondlight
`channel 236. In an exemplary embodiment, the first and
`second light sources 230 and 234 are positioned within the
`first portion 202 andthe first and second light channels 232
`and 234 are configured to direct light from the first and
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`US 7,107,088 B2
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`5
`to the first optically
`second light sources, respectively,
`transparent portion 224a. In an alternative embodiment, the
`light sources 230 and 234 may bepositioned within the
`second portion 212 with leads (not shown) for powering the
`light sources extending from a power source (not shown) in
`the first portion 202 to the first and second light sources in
`the second portion 212. The first and second light sources
`230 and 234 maybelight emitting diodes (LEDs, e.g., a 660
`nm LEDand an 805 nm LED) andthefirst and second light
`channels 232 and 236 may be optical fibers.
`A detector 238 is positioned within the oximetry sensor
`200 to detect light of the two or more wavelengths out of a
`second position of the vascular tissue 29 impinging a
`corresponding second optically transparent portion 2245 of
`the second portion 212 when the oximetry sensor 200 is
`positioned within the auditory canal 100. The illustrated
`detector 238 includes a photodetector 240 (e.g., a photo
`diode) and a third light channel 242 (e.g., an optical fiber).
`In an exemplary embodiment,
`the photodetector 240 is
`positioned within the first portion 202 and the third light
`channel 242 is configured to direct
`light
`impinging the
`second optically transparent portion 2245 of the second
`portion 212 through the second portion 212 to the photode-
`tector 240 in the first portion 202. In an alternative exem-
`plary embodiment, the photodetector 240 maybepositioned
`within the second portion 212 with a lead (not shown)
`extending from the photodetector 240 to oximetry circuitry
`244 in the first portion 202. The first and second optically
`transparent portions 224a and 2246 may form channels on
`the surface of the second portion 212 for respectively
`emitting and detecting light along the channels to maximize
`coupling and to limit the effects of blockage do to wax
`build-up.
`FIGS. 4A, 4B, and 4C depict cross sectional views of
`exemplary second portions 212 for delivering light to the
`first and second positions of the vascular tissue in the third
`region 25. The cross sectional views each include an opti-
`cally blocking portion 226 andoptically transparent portions
`224. The illustrated cross sectional second portions each
`include twotransparent portions 224—a light emitting opti-
`cally transparent portion 224a anda light receiving optically
`transparent portion 2245. Thelight emitting portion 224ais
`coupled to the first and second light sources 230 and 234
`(FIG. 2) and the light receiving portion 2246 is coupled to
`the photodetector 240, e.g., via optical fibers 232, 236, and
`242. The light emitting portion 224a emits light from the
`light sources to the first position of the vascular tissue 29
`when the oximetry sensor 200 is positioned within the
`auditory canal and the light receiving portion 2246 collects
`light from the secondposition of the vascular tissue 29 when
`the oximetry sensor 200 is positioned within the auditory
`canal.
`
`In FIG.4A,the light emitting portion 224a andthe light
`receiving portion 224d are radially positioned substantially
`opposite one another, e.g., about 180 degrees apart, such that
`the first and second positions on the vascular tissue are on
`opposite sides of the second portion 212 (FIG. 2). In FIG.
`4B, the light emitting portion 224a and the light receiving
`portion 2246 are radially positioned approximately 90
`degrees with respect to one another. In FIG. 4C, the light
`emitting portion 224a andthe light receiving portion 2245
`are radially positioned approximately 45 degrees with
`respect to one another. In an exemplary embodiment, the
`light emitting portion 224a and the light receiving portion
`2246 are radially positioned relative to one another between
`about 5 degrees and 180 degrees. In an alternative exem-
`plary embodiment, the light emitting portion and the light
`
`6
`receiving portion mayradially overlap, but be separated in
`a longitudinal direction by the optically blocking portion
`226, e.g., along the length of the elongated passage 222
`(FIG. 2) extending through the second portion 212.
`Referring back to FIG. 2, the oximetry circuitry 244 is
`configured to process information corresponding to the two
`or more wavelengths of light received by the detector 238.
`In addition, the oximetry circuitry 244 may be configured to
`control the emitter 228. The oximetry circuitry 244 may be
`coupled to the emitter 228 and the detector 238 via traces of
`a circuit board 246. The oximetry circuitry 224 may be
`configured to calculate an oximetry value based on the
`received two or more wavelengths of light. In addition, the
`oximitry circuitry 244 may be configured to calculate pulse
`rate. Suitable methods for calculating oximetry levels and
`pulse rates will be understood by those of skill in theart.
`The exemplary oximetry circuitry 244 further includes an
`emitter 248 for wireless transmission of information related
`to the two or more wavelengthsoflight and/or a port 250 for
`wired transmission of information related to the two or more
`wavelength of light. The information related to the two or
`more wavelengths of light may be values calculated by the
`oximetry circuitry 244 or raw data detected by the detector
`238. A suitable oximetry circuit for use in the present
`invention will be understood by those of skill in theart.
`FIG. 5 depicts a flow chart 500 of exemplary steps for
`detecting oxygen saturation levels in blood from within an
`auditory canal ofa living being. The steps are described with
`reference to FIGS. 1 and 2.
`At block 502, the emitter 228 emits light of two or more
`wavelengths into a first position on the vascular tissue 29 of
`the auditory canal 100 in the third region 25, which is
`defined by the distal bend 31 and the tympanic membrane
`26. At least one of the wavelengths of light is much less
`sensitive to blood oxygen saturation levels than at least one
`of the other wavelengths of light. The wavelength of light
`that is sensitive to blood oxygen saturation levels may be the
`isobestic wavelength, which for oxygenated blood is 805
`nm, e.g., infrared light. After the oximetry sensor 200 is
`positioned within the auditory canal 100, the emitter 204
`emits the two or more wavelengths oflight, e.g., from light
`sources 230 and 234, responsive to the oximetry circuitry
`244.
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`In an exemplary embodiment, the oximetry circuitry 244
`is configured to modulate the emitter 228 to cause a first
`light source, e.g., light source 230, to emit light for one-third
`(4) of a proposed cycle time; to cause a secondlight source,
`e.g., light source 234, to emit light during a second one-third
`of the cycle time; and to cause no light to be emitted during
`a final one-third of the cycle time. During the period of time
`in which no light is emitted, the detector 238 may measure
`background light intensity levels for subtraction from the
`measure light intensity signals when light is being emitted to
`increase accuracy.
`In an exemplary embodiment, the wavelengths of light are
`generated in the first portion 202 and are passed to the
`emitting optically transparent portion 224a@ of the second
`portion 212, e.g., via optical fibers 232 and 234, where they
`are emitted into the first position on the vascular tissue 29.
`In an alternative exemplary embodiment, the wavelengths of
`light originate in the second portion 212 responsive to
`electrical signal from the oximetry circuitry 244.
`Atblock 504, the detector 238 detects the intensity of the
`two or more frequencies of light at a second position on the
`vascular tissue 29 of the auditory canal 100 in the third
`region 25. The second position is spaced from the first
`position and the light detected by the detector 228 is light
`011
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`

`US 7,107,088 B2
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`the tympanic membrane when the apparatus is posi-
`that has passed through the vascular tissue 29 from the first
`tioned within the auditory canal;
`position to the second position. In an exemplary embodi-
`a second portion movably coupledto the distal end of the
`ment,
`the detector 238 sequentially detects the light as
`first portion, the second portion comprising an outer
`emitted by the emitter 228.
`surface configured to abutat least a portion ofthe tissue
`light from the second
`In an exemplary embodiment,
`of the auditory canal between the distal bend and the
`position of the vascular tissue 29 impinges upon the opti-
`tympanic membrane when the apparatus is positioned
`cally transparent portion 2246 of the second portion 212 and
`within the auditory canal,
`is passed to the photo detector 240 in the first portion 202,
`an emitter that emits light of one or more wavelengths
`é.g., Via an optical fiber 242, for detection and communica-
`
`tion to the oximetry circuitry 244. In an alternative exem- fromafirst position on the outer surface of the second
`plary embodiment,the light is detected in the second portion
`portion into the tissue of the auditory canal between the
`and an electrical signal including intensity information cor-
`distal bend and the tympanic membrane; and
`respondingto the detected light is passed to the first portion,
`a detector that detects the light of one or more wave-
`é.g., via a transmission line.
`lengths from the tissue of the auditory canal between
`As used herein, the phrase “intensity information corre-
`the distal bend and the tympanic membrane impinging
`sponding to the two or more frequencies of light” detected
`upon a second position on the outer surface of the
`in the third region 25 may beusedto referto the actual light
`second portion.
`or to an electrical signal representing the actual light. In an
`2. The apparatus of claim 1, wherein the first portion is
`exemplary embodiment, this information passes from the
`substantially rigid and the second portion extends from the
`third region 25 to another region (e.g., within the auditory
`first portion and is relatively flexible such that the second
`canalor outside of the auditory canal) distinct from the third
`portion is movable relative to the first portion to at least
`region 25 througha flexible coupling (e.g., a flexible second
`partially isolate the second portion from movement of the
`portion 202 coupled to the first portion 212 or a mechanical
`first portion.
`joint connecting the first and second portions 202 and 212).
`3. The apparatus of claim 1, further comprising a joint
`At block 506,
`the oximetry circuitry 244 calculates a
`coupled between the distal end of the first portion and the
`blood oxygen saturation level responsive to the intensity
`second portion.
`information corresponding to the two or more wavelengths
`4. The apparatus of claim 1, the second portion having a
`of light detected at the second position. Since one of the
`proximalend coupledto the distal end ofthe first portion and
`frequencies of light is less sensitive to oxygen saturation
`a tympanic end extending toward the tympanic membrane
`levels than the other,
`this frequency of light provides a
`when the apparatus is positioned within the auditory canal,
`“base-line” against which a frequency of light that is more
`the second portion further comprising a first hollow body
`sensitive to oxygen saturation can be compared in order to
`portion defining an elongated passage extending between the
`calculate blood oxygen saturation levels in a mannerthat
`proximalend and the tympanic endofthe second portion for
`will be understood by those of skill in the art. The oximetry
`communication of acoustic signals through the second por-
`circuitry 244 may alternatively or additionally calculate
`tion between the first portion and the tympanic membrane.
`pulse rate responsive to the information in a mannerthat will
`5. The apparatus of claim 4, wherein the first portion has
`also be understood by those of skill in the art. The absolute
`an outer end portion substantially opposite the distal end, the
`strength of the signal is dynamic and cyclic being responsive
`first portion further comprising a second hollow body por-
`to the pulsitile arterial blood flow—peak to peak measure-
`tion defining an elongated passage extending between the
`ments determine pulse. For a modulated light source, the
`outer end and distal end of the first portion for communi-
`light source should be modulated at a frequency ofat least
`cation of acoustic signals throughthe first portion to the first
`twice that of the highest frequency to be measured, e.g., at
`hollow body portion of the second portion.
`300 Hz or more to measure a pulse rate of 150 beats per
`6. The apparatus of claim 1, wherein the emitter com-
`minute or less. In accordance with this embodiment, light of
`prises:
`only one wavelength is needed and, thus, only one light
`a light source positioned within the first portion;
`source (e.g., a single LED)that is sensitive to blood oxygen
`an optical channel extending from the light source
`saturation levels is needed. In an exemplary embodiment,
`through the second portion to the first position.
`the oximetry circuitry 244 calculates the blood oxygen
`7. The apparatus of claim 1, wherein the detector com-
`saturation level and/or pulse rate in a region other than the
`prises:
`third region 25, e.g., within another region of the auditory
`a photo-detector positioned within thefirst portion;
`canal 100 or external to the auditory canal.
`an optical channel extending from the second position on
`Althoughthe invention is illustrated and described herein
`the second portion to the photo-detector.
`with reference to specific embodiments, the invention is not
`8. The apparatus of claim 1, further comprising:
`intendedto be limited to the details shown. Rather, various
`oximetry circuitry coupled to the detector, th