US006014576A
`6,014,576
`(114) Patent Number:
`United States Patent 55
`Raley
`[45] Date of Patent:
`Jan. 11, 2000
`
`
`[54] SEGMENTED
`PHOTOPLETHYSMOGRAPHIC SENSOR
`WITH UNIVERSAL PROBE-END
`
`[75]
`
`Inventor: Dena M.Raley, Louisville, Colo.
`
`[73] Assignee: Datex-Ohmeda, Inc., Louisville, Colo.
`
`[21] Appl. No.: 09/031,575
`
`Feb. 27, 1998
`
`[56]
`
`[57]
`
`ABSTRACT
`.
`.
`.
`A two piece probe having a universal probe end and an
`interconnect cable segment provides for the use of the
`universal probe end with a variety of different photoplethys-
`mographic devices. The universal probe end includes a
`detector, a substrate for removably affixing the probe end to
`P
`Pp
`a
`patient, a window or aperture and a connector. The
`interconnectcable has a connector mated to the connector on
`the probe end for mechanical and electrical connection of
`the probe-end to the interconnect cable and the photopl-
`ethysmographic monitor. The connector end of the intercon-
`nect cable also houses a plurality of emitters which are
`directed through the window oraperture in the probe end in
`orderto illuminate the patient. The interconnect cable also
`houses the resistors or other elements which identify the
`type of probe, monitor manufacturer or actual emitter wave-
`lengths. Alternatively, the emitters may be housed in the
`main monitor and an optical fiber may be used to direct light
`to the patient. An electrical conductor transmits light
`received by the detector back to the photoplethysmographic
`monitor.
`
`Filed:
`[22]
`A61B 5/00
`Int. C1’
`[51]
`Nc ceecsccneseseceeestenseenneenesse
`[52] US. CU. eeeeceecscsseeeeeenees 600/344; 600/310; 600/322
`[58] Field of Search occ 600/310, 322,
`600/323, 326, 333, 344
`.
`References Cited
`U.S. PATENT DOCUMENTS
`oes io!903 cue eetCe eonse
`5249,
`oldberger et al. 0c
`Primary Examiner—Enic F. Winakur
`Attorney, Agent, or Firm—Holme Robert & Owen LLP
`
`21 Claims, 7 Drawing Sheets
`
`1
`
`APPLE 1047
`Apple v. Masimo
`IPR2022-01291
`
`APPLE 1047
`Apple v. Masimo
`IPR2022-01291
`
`1
`
`

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`Sheet 1 of 7
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`U.S. Patent
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`FIG.1
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`Sheet 3 of 7
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`FIG.3 21,22,23,24
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`U.S. Patent
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`Jan. 11, 2000
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`Sheet 6 of 7
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`6,014,576
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`U.S. Patent
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`Jan. 11, 2000
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`Sheet 7 of 7
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`6,014,576
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`1
`SEGMENTED
`PHOTOPLETHYSMOGRAPHIC SENSOR
`WITH UNIVERSAL PROBE-END
`
`FIELD OF THE INVENTION
`
`This invention related to medical monitoring probes used
`in photoplethysmographic monitors and, in particular, to a
`probe architecture that enables the user of a photoplethys-
`mographic monitor to use a universal probe-end for all
`monitors in combination with a probe-interconnect cable
`which is designed for a specific type of monitor.
`BACKGROUND OF THE INVENTION
`
`It is a problem in the field of medical monitoring instru-
`ments to manufacture a photoplethysmographic probe that
`satisfies a number of diverse and sometimes contradictory
`requirements. It is important that the probe both be simple
`to use and conform to a variety of patients whodiffer in size
`and shape. The probe must be securely affixable to the
`patient, such as on a patient’s appendage, without requiring
`complex structures or elements that can irritate the patient.
`In addition,
`in order to reduce the risk of infection and
`contamination,at least a portion of the probe should be built
`to be disposable so that the probe is used one or more times
`with the patient and can then be destroyed. The disposable
`portion of the probe must be inexpensive so that it can be
`disposable after use and yet the patient must be shielded
`from any potentially dangerous electrical signals or heat
`produced by the probe. The probe must also reliably and
`accurately perform the required blood analyte measure-
`ments. The probe, cable and monitoring instrumentare all
`subjected to a hostile environment and must be manufac-
`tured to be rugged to survive rough handling and the
`presence of highly reactive fluids.
`Another problem with present photoplethysmographic
`probes is the proliferation of probe types and monitor
`models. The number of manufacturer designs probes for use
`with their specific monitors. Also, the types of photoplethys-
`mographic monitors continues to increase. One of the pri-
`mary uses of photoplethysmography has been the monitor-
`ing of the oxygen saturation of a patient’s blood. However,
`there is a desire to expand the use of photoplethysmography
`into the monitoring of additional blood analytes such as
`carboxyhemoglobin, methemoglobin and other dyshemo-
`globins. This proliferation of monitor types will add addi-
`tional confusion in the health care environment due to the
`numberof additional probe types which will be offered with
`these new monitors.
`
`In the specific field of pulse oximetry, the light beamsare
`typically generated by a probe using light emitting diodes
`(LEDs) that produce light beamsat red and infrared wave-
`lengths. Various manufacturers use different wavelengths of
`LED’s in illuminating the tissue of a patient. Additionally,
`many manufacturers use LED’s which producelight having
`a spectral content characterized by a center wavelength
`which varies from the nominal wavelength of the LED.
`Therefore, many photoplethysmographic probes use one or
`more meansfor identifying characteristics about the probe
`being used. One commonidentification meansis a resistor
`which resides in the probe and identifies the spectral char-
`acteristics of the emitters being used in the probe thereby
`enabling the photoplethysmographic monitor to utilize the
`correct calibration data when generating the blood analyte
`level. Another use of the identification meansis identifying
`the type or manufacturer of a probe. Presently, however,
`there are no probes which can universally be used with all
`manufacturer’s phtotoplethysmograhpic monitors.
`
`2
`In future photoplethysmographic systems it may be pref-
`erable to use laser diodes, which produce a beam of sub-
`stantially monochromatic light at or exceeding the light
`poweravailable from light emitting diodes that are typically
`used in photoplethysmography. The difficulty with laser
`diodesis that their cost currently prevents them from being
`used in a disposable probe. Placement of the laser diode in
`the monitoring instrument necessitates the use of one or
`more fiber optic strands in the cable that interconnects the
`disposable probe with the monitoring instrument. The cable
`in a hospital environment typically suffers rough handling
`and the life of the fiber optic strands in the connector cable
`can befairly limited, thereby increasing the effective cost of
`the disposable probe since the cable must
`typically be
`replaced on a fairly frequent basis.
`Alternatively, the laser diodes can be placed in a segment
`of the interconnect cable between the monitor and the
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`patient end of the probe. This, however,still requires that the
`segment of the interconnect cable housing the laser diodes
`be reusable in order to reduce costs.
`
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`SUMMARYOF THE INVENTION
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`The above-described problemsare solved and a technical
`advance achieved in the field of medical monitoring instru-
`ments by the apparatus of the present invention which makes
`use of a universal probe-end that can be attached to a
`plurality of monitor specific interconnect cables. This
`enables the health care provider to stock only one type of
`disposable probe-end. The reusable manufacturer specific
`interconnect cable can remain attached to the monitor with
`
`which it is being used until the reusable cable requires
`replacement. In the preferred embodimentdisclosed herein,
`the disposable probe-end has a u-shaped channel for receipt
`of a u-shaped interconnect cable end portion which houses
`either the required LED’s, laser diodes or optical fiber and
`mirrors for illuminating the tissue of a patient. The dispos-
`able probe-end may include a window in orderto protect the
`patient from excess heat being emitted form the light sources
`and to protect the reusable interconnect cable from contami-
`nation. The required identification means is housed in the
`reusable interconnect cable, thus, the disposable probe-end
`can havetruly universal application across all photoplethys-
`mographic monitors.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a top perspective view of the disposable probe-
`end of an embodiment of the present invention.
`FIG. 2 is top perspective view of the interconnect cable
`segment of an embodiment of the present invention.
`FIG. 3 is a bottom perspective view of the interconnect
`cable segment of one embodimentof the present invention.
`FIG. 3b is a bottom perspective view of the interconnect
`cable segment of an alternative embodimentof the present
`invention.
`
`FIG. 4 is a top perspective view of the combined probe-
`end and interconnect cable segment of an embodimentof the
`present invention.
`FIGS. 5 and 6 illustrate the two types of photoplethys-
`mographic monitors.
`DETAILED DESCRIPTION
`
`The apparatus of the present invention represents a pho-
`toplethysmographic probe architecture which will reduce
`the proliferation of disposable probe types and result in
`cost-savings and ease of use for the health care provider.
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`6,014,576
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`3
`One type of photoplethysmographic monitor, a pulse
`oximeter, is frequently used to monitor the condition of a
`patient in a hospital setting. The pulse oximeter instrument
`noninvasively measures the oxygen saturation of the arterial
`blood and produces a human readable display that indicates
`both the patient’s heart rate and the oxygen saturation of the
`arterial blood. These readings are important to enable the
`medical staff to determine whether the patient’s respiratory
`system is functioning properly, supplying sufficient oxygen
`to the blood.
`
`A pulse oximeter instrument operates by use of a probe
`that illuminates an appendageofthe patient (such as a finger,
`earlobe, toe, neonatal appendages, or the nasal septum) that
`is rich in arterial blood and measuresthe differential absorp-
`tion of the light by the pulsatile portion of the arterial blood
`flow to thereby determine oxygen saturation of the arterial
`blood. The pulse oximeter instrument makes use of a plu-
`rality of light-emitting devices, each of which transmitslight
`at a predetermined wavelength, which wavelengths are
`selected such that at least one is highly absorbed by oxy-
`genated hemoglobin in the arterial blood andat least one is
`highly absorbed by reduced hemoglobin in the arterial
`blood. The amount of absorption of the light beams gener-
`ated by these light emitting devices that are located in the
`probe is a measure of the relative concentration of the
`various hemoglobin species contained in the arterial blood.
`The absorption ofthe lightthat illuminates the appendage of
`the patient includes a constant portion thatis a result of skin,
`bone, steady-state (venous) blood flow andlight loss due to
`various other factors. The pulsatile componentof absorption
`is due to the pulsatile arterial blood flow and is a small
`fraction of the received signal and is used by the pulse
`oximeter instrument to perform its measurements. It is also
`possible to measure additional analytes in the arterial blood,
`such as additional dyshemoglobins, with one additional
`wavelength of light for each component.
`The measurements are computed by sampling the output
`of the light detector located in the probe to determine the
`incremental change in absorptionof the various wavelengths
`of light that are used to illuminate the appendage of the
`patient. These incremental changes in light absorption are
`then used to compute the oxygen saturation of the arterial
`blood as well as the patient’s pulse rate. Since the pulsatile
`component of the signals received by the light detector
`represent only a small fraction of the incident light, it is
`important that the incidentlight be of significant magnitude
`to result in transmitted signals that have sufficient amplitude
`to provide accurate readings. In addition, the probe contain-
`ing the light-emitting devices and the light detector must be
`placed in intimate contact with the skin of the patient to
`obtain the most accurate readings.
`Referring to FIGS. 1, 2, 3, 4, 5 and 6, the probe 40 of the
`present invention is designed for use with one of two basic
`photoplethysmographic monitor architectures depicted in
`FIGS. 5 and 6. FIG. 5 depicts one of the monitor architec-
`tures in which the monitor 100 communicates with probe 40
`through socket 104 and mating interconnect cable plug 42.
`The configuration of plug 42 depends on the type and
`manufacturer of monitor 100. For example, if the monitor
`100 is capable of measuring a plurality of blood analyte
`concentrations such as O2Hb, RHb, COHb and MetHBthen
`plug 42 and interconnect 104 will contain sufficient electri-
`cal connectors 46 to interconnect probe interface 102 with a
`plurality of emitters 21, 22, 23 and 24 located in the
`connector-end 25 of interconnect cable segment 20. In a
`preferred embodiment, the plurality of emitters 21, 22, 23
`and 24 each emit light having a distinct spectral content
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`characterized by a distinct center wavelength denoted by i,
`h, hz and X,. These emitters may be light-emitting-diodes
`(LED’s) or laser diodes.
`It
`is also possible to filter a
`broadband light source to produce light having four spectral
`peaksof differing wavelengths. In a photoplethysmographic
`instrument designed to generate four blood analyte levels,
`the preferred embodiment is to use at least four separate
`emitters each producing light with a distinct spectral con-
`tent. If fewer blood analyte levels are desired then fewer
`emitters may be used either in the interconnect cable. For
`example, in a probe made according to the present invention
`for use with a standard pulse oximeter, only two emitters
`would be needed in the interconnect cable.
`
`Probe identifier 47 is located in cable 28, for example in
`plug 42, and provides a means for identifying the type or
`family of the probe (ear, finger, toe etc.) or a means for
`identifying the manufacturer of the probe or a means for
`identifying the actual center wavelength of each of the
`plurality of emitters in the interconnect cable. The configu-
`ration of plug 42 and probe identifier 47 will be dictated by
`the photoplethysmographic monitor for which interconnect
`cable 28 is designed. Probe identifier 47 may bea resistor or
`set of resistors, a diode or set of diodes or some other
`electrical identifier. It is also possible that more than one
`identier may be necessary if,
`for example,
`information
`regarding both probe family as well as actual emitter wave-
`length must be communicated from the interconnect cable to
`the photoplethysmographic monitor.
`The intensity of light transmitted through the tissue under
`test is measured by one or more photodetectors 13 which are
`located in the disposable probe-end 10. Photodetector 13
`provides a signal corresponding to the intensity of light
`received denoted I,,, I,2, I,3 and I,,. This signal is then
`electrically routed back to the monitor 100 through cable 28,
`plug 42 and socket 104 to the probe interface 102. In the
`monitor the analog received intensity signals, I,,, I,2, I3
`and I,, are converted into digital signals through a well-
`known analog to digital (A/D) converter. The intensity
`signals are then stored in memory 106 and manipulated in
`data processing circuit 107 of the monitor 100 according to
`data processing instructions stored in memory 106 and
`executed by the data processing circuit 107 in order to
`determine an estimate of the blood analyte levels output as
`a percentage concentration. Blood analyte levels (output as
`percentages) may then be displayed via display driver 109
`and graphic display 114 and/or numeric display 115.
`An alternative method of implementing a photoplethys-
`mographic monitor is depicted in FIG. 6 and operates in
`conjunction with the alternative probe embodiment in FIG.
`3b. The emitters 21, 22, 23 and 24 (which may be LED’s or
`laser diodes, but which are preferably laser diodes) are
`housed in the monitor 200. The emitters 21, 22, 23 and 24
`are driven by emitter driver 230 which is controlled by the
`data processing circuit 107. The emitted light is then com-
`bined by an optical coupler 228 and transmitted to the probe
`40 by internal optical fiber 260 which is coupled to an
`optical fiber or other such optically transmissive material
`(not shown) internal to interconnect cable segment 28. Thus,
`plug 42 and connector 204 now includeselectrical conduc-
`tors for connecting photodiode 13 back to the probe inter-
`face 102 and an optical connector for connecting optical
`fiber 260 to an optical fiber (not shown) located in cable 28.
`The light
`transmitted through the optical fiber 260 and
`transmitted through the optical fiber located in cable 28,
`reflects off mirror 29 of FIG. 3b in connector end 25 and
`passes through window or opening 26 and window 16 in
`probe-end 10 and impinges on the tissue of the patient.
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`6,014,576
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`5
`Transmitted light is received by photodetector 13 which
`send an electrical signal back to the probe interface 102
`through the electrical conductors in cable 28 and electrical
`pathway 262 in monitor 200. The probe interface 102
`converts the analog signal to a digital signal and transmits
`the signal to memory 106 and on to data processing circuit
`107 for processing and display of blood analyte concentra-
`tion values using graphic display 114 and numeric display
`115 driven by display driver 109. The transmission of the
`emitted light can be controlled in a time division multiplex-
`ing manner and an optical coupler 228 can be used to
`provide a means for combining multiple emitters onto one
`strand of optical fiber 260. Alternatively, the plurality of
`emitters may be placed or abutted against optical fiber 260.
`The Probe
`Referring again to FIG. 4 the probe 40 consists of two
`releasable connected segments: the probe-end 10, separately
`depicted in FIG. 1 and interconnect cable segment 20,
`separately depicted in FIGS. 2, 3 and 3b.
`Universal probe-end 10 is designed to be disposable and
`to accommodate any type of interconnect cable segment 20,
`whether it contains LED’s, laser diode, or an optical fiber/
`mirror for illuminating the tissue. Thus, the construction of
`probe-end 10 is simple and flexible consisting of a flexible
`substrate 11 having three portions 12a, 12b and 12c. Sub-
`strate portions 12a and 125 are designed to wrap around an
`appendage of a patient. In FIG. 1 the substrate is designed
`to be wrapped around a finger. Substrate portions 12a and
`12b have an adhesive layer applied to one or more surfaces
`to enable the portions to be removably attachedto the finger.
`Substrate portions 12a and 12b may be configured differ-
`ently for attachment of probe-end 10 to the feet of neonates,
`the smaller fingers of children, or to other appendages of
`adult, child or neonatal patients.
`Substrate portion 12¢ includes a photodetector 13 which
`is mounted in an optically transmissive window 19 in the
`substrate 11 and which is connected to connector 17 through
`flexible electrical circuits 14 a—d. Connector 17 hasthree lip
`portions 17a, 17b, and 17¢ which are designed to accom-
`modate and hold the connector-end 25 of interconnect cable
`
`segment 20. Connector portion 15 provides a larger surface
`area for connector 17 to be either adhesively affixed to
`substrate 12 or, alternatively, to be retained between layers
`of substrate 12. Connector 17 also houses an optically
`transmissive window 16 and electrical contacts 18a, 185,
`18c, and 18d which connect flexible electrical circuits 14a,
`b,c and d with interconnect cable segment 20.
`Window 16 enables light to be passed from the emitters
`21,22,23 and 24 or optical fiber and mirror 29 to the patient
`while protecting the patient from excess heat and also
`protecting the reusable interconnect cable segment 20.
`FIG. 2 depicts a top elevational view of the patient end of
`interconnect cable segment 20. Cable 28 consists of a bundle
`of one or more electrical conductors and, if the emitters are
`located in the monitor 200, an optical fiber. The electrical
`conductors and optical fiber are covered by a flexible
`insulating material to protect the internal components. Con-
`ductive grooves 28a, 28b, 28c and 28d provide for electrical
`interconnection of photodetector 13 through flexible con-
`ductors 14a, 14b, 14c and 14d and electrical contacts 18a,
`18b, 18c and 18d. Ridge 27b is designedto fit under lip 17b
`to hold connector-end 25 onto probe-end 10.
`FIG. 3 depicts a bottom elevational view of one embodi-
`ment of the patient end of interconnect cable segment 20.
`The embodiments of FIG. 3 includes four emitters 21, 22, 23
`and 24. Such an embodiment would be useful in a photop-
`lethysmographic monitor for measuring three or four blood
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`analytes such as oxyhemoglobin, deoxyhemoglobin, car-
`boxyhemoglobin and methemoglobin. Alternatively,
`the
`number of emitters could be two in a probe for use with
`standard pulse oximeters which typically use two emitters
`having spectral contents characterized by distinct center
`wavelengths, often 660 nm and 940 nm. Ridges 27a, 27b
`and 27c fit under lip portions 17a, 17b and 17c to hold
`connector-end 25 onto probe end 10. The end oflatch 30 is
`designed to click into a hole near the base of lip portion 17c
`so that upon engagement of the connector-end 25 into
`connector 17 a releasable latching occurs. In order to dis-
`engage the latching mechanism latch 30 is simply depressed.
`FIG. 3b depicts essentially the identical
`interconnect
`cable segment 25 with the exception that emitters 21, 22, 23
`and 24 have been replaced by mirror assembly 29 which
`reflects light from the optical fiber enclosed in cable 28
`which endsnear opening 26 through window 16 and onto the
`tissue of the patient.
`While various embodiments of the present invention have
`been described in detail, it is apparent that modifications and
`adaptations of those embodiments will occurto those skilled
`in the art. For example, it should be appreciated that the
`method and apparatus as taught by the present invention
`may be modified in an unlimited number of ways within the
`framework of the teachings of the present invention. These
`variations are all considered to fall within the scope of the
`present invention. Therefore, it is to be expressly understood
`that such modifications and adaptations are within the spirit
`and scope of the present
`invention, as set forth in the
`following claims.
`I claim:
`1. A probe for illuminating tissue of a subject to measure
`light absorption of said tissue by a photoplethysmographic
`measurement system, comprising:
`a universal probe-end and an interconnect cable segment
`having a connector-end;
`said universal probe-end comprising:
`a flexible substrate for removably affixing said probe-
`end to said tissue, wherein a first side of the flexible
`substrate is affixable to contact said tissue;
`a connector, fixedly attached to a second side of said
`substrate, adapted to receive said connector-end of
`said interconnect cable, wherein said second side of
`the substrate is opposite to said first side;
`a plurality of electrical contacts housed by said con-
`nector;
`an optically transmissive window housed by said con-
`nector;
`a photodetector mounted in the flexible substrate; and
`a first plurality of flexible electrical conductors extend-
`ing between said photodetector and said plurality of
`electrical contacts;
`said interconnect cable segment comprising a plurality of
`electrical and/or optically transmissive conductors and
`a plug at the end opposite said connector-end adapted
`for electrical and/or optical attachmentof said plurality
`of electrical and/or optically transmissive conductors to
`one or more specific photoplethysmographic measure-
`ment systems, wherein said connector-end further com-
`prises:
`a housing having an aperture on one surface, wherein
`said aperture is aligned with said optically transmis-
`sive window upon interconnection of said connector
`end to said universal probe-end;
`a light source located internal
`to said housing and
`arranged so as to emit light through said aperture,
`wherein the optically transmissive window of the
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`6,014,576
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`7
`universal probe enablesthe light to pass therethrough
`to the tissue while protecting the connector-end of
`the interconnectable cable segment from contamina-
`tion when the connector endis interconnected to the
`universal probe-end; and
`a second plurality of electrical contacts on said
`connector-end of said interconnect cable adapted to
`contact said first plurality of contacts, wherein said
`light sourceis electrically and/or optically connected
`to said plurality of electrical and/or optically trans-
`missive conductors, and wherein said second plural-
`ity of electrical contacts are electrically connected to
`said plurality of electrical conductors upon intercon-
`nection of said connector end to the universal probe-
`end.
`
`2. The probe of claim 1 wherein said light source internal
`said interconnect cable segment housing is a plurality of
`light emitting diodes and, said plurality of light emitting
`diodes is electrically connected to said photoplethysmo-
`graphic measurement system.
`3. The probe of claim 1 wherein said light source internal
`said interconnect cable segment housing is a plurality of
`laser diodes and, said plurality of laser diodes is electrically
`connected to said photoplethysmographic measurementsys-
`tem.
`
`4. The probe of claim 1 wherein said light source internal
`said interconnect cable segment housing is an optical fiber
`adapted to be illuminated by a plurality of emitters located
`inside said photoplethysmographic measurement system.
`5. The probe of claim 4, further comprising a mirror
`located internal said housing of said connector-end and
`adapted to reflect light from said optical fiber through said
`aperture in said housing.
`6. The apparatus of claim 1 wherein said connectorof said
`probe-end comprises:
`a u-shaped lip adapted to receive the apertured surface of
`said connector-end.
`
`7. The apparatus of claim 6, wherein said connector end
`further comprises a u-shaped ridge adapted to be received
`under said u-shaped lip of said connector of said probe-end.
`8. The apparatus of claim 6, wherein said connector
`further comprises a latch for releasable latching upon
`engagement of said connector end into said connector.
`9. A probefor illuminating tissue of a subject to measure
`light absorption of said tissue by a photoplethysmographic
`measurement system, comprising:
`a universal probe-end and an interconnect cable segment
`having a connector-end;
`said universal probe-end comprising:
`a flexible substrate for removably affixing said probe-
`end to said tissue;
`a connector,
`fixedly attached to one side of said
`substrate, adapted to receive said connector-end of
`said interconnect cable;
`a plurality of electrical contacts housed by said con-
`nector;
`an optically transmissive window housed bysaid con-
`nector and said substrate;
`a photodetector Mounted in the flexible substrate; and
`a plurality of flexible electrical conductors extending
`between said photodetector and said plurality of
`electrical contacts;
`said interconnect cable segment comprising a plurality of
`electrical and/or optically transmissive conductors, a
`plug at the end opposite said connector-end adapted for
`electrical and/or optical attachmentof said plurality of
`electrical and/or optically transmissive conductors to
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`one or more specific photoplethysmorgraphic measure-
`ment systems, and means for identifying one or more
`characteristics of the probe to said photoplethysmo-
`graphic system, and wherein said connector-end further
`comprises:
`a housing having an aperture on one surface, wherein
`said aperture is aligned with said optically transmis-
`sive window upon the connection of said connector
`end to said universal probe-end;
`a light source located internal
`to said housing and
`arranged so as to emit light through said aperture,
`wherein the optically transmissive window of the
`universal probe enables the light to pass therethough
`to tissue of a subject while protecting the connector-
`end of the interconnectable cable segment from
`contamination when the connector end is intercon-
`nected to the universal probe-end;
`a second plurality of electrical contacts on said
`connector-end of said interconnect cable adapted to
`contact said first plurality of contacts, wherein said
`light sourceis electrically and/or optically connected
`to said plurality of electrical and/or optically trans-
`missive conductors, and wherein said second plural-
`ity of electrical contacts are electrically connected to
`said pluarality of electrical conductors upon inter-
`connection of said connector end to the universal
`probe-end.
`10. The probe of claim 9, wherein said characteristics of
`the probe are selected from the group consisting of probe
`type, photoplethysmographic system manufacturer and
`actual emitter wavelength.
`11. A probe apparatus for illuminating tissue of a subject
`to measure light absorption of said tissue by a photoplethys-
`mographic measurement system, comprising:
`a universal probe end and an interconnect cable segment
`having a connector-end;
`said universal probe-end comprising a photodetector, a
`connector adapted to receive said connector-end of said
`interconnect cables and an electrical conductor for
`connecting said photodetector to said connector, and
`wherein said probe-end has a opening aperture therein;
`said interconnect cable segment including:
`a plurality of emitters for emitting light through said
`aperture;
`a plurality of electrical conductors connected to said
`emitters and connectable to said connector;
`a plug at the end opposite said connector-end adapted
`to electrically connect said plurality of electrical
`conductors to one of a plurality of photoplethysmo-
`graphic measurement systems; and
`means for identifying a characteristic of the probe
`apparatus to said photoplethysmographic system.
`12. The probe apparatus of claim 11 wherein the charac-
`teristic of the probe apparatus is selected from the group
`consisting of probe type, photoplethysmographic system
`manufacturer and actual emitter wavelength.
`13. The probe apparatus of claim 12 wherein the identi-
`fication means comprises one or more electrical elements.
`14. The probe apparatus of claim 13 wherein the identi-
`fication means comprises a plurality of resistors indicative of
`the actual wavelength of each of the plurality of emitters in
`said interconnect cable.
`15. The apparatus of claim 11, wherein the identified
`characteristic is employable by the photoplethysmographic
`system to select a calibration curve for measurement deter-
`minations.
`
`16. A probe apparatus for illuminating tissue of a subject
`to measure light absorption of said tissue by a photoplethys-
`mographic measurement system, comprising:
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`6,014,576
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`a universal probe-end and an interconnect cable segment
`having a connector-end,
`said universal probe-end comprising a photodetector, a
`connector adapted to receive said connector-end of said
`interconnect cable, and an electrical conductor for
`connecting said photodetector to said connector,
`wherein said probe-end has an aperture therein;
`said interconnect cable segment including:
`through said
`a mirror located so as to direct
`light
`aperture, an optical fiber for directing light from a
`photoplethysmogmaphic measurement system onto
`said mirror;
`an electrical conductor connected to said connector;
`a plug at
`the end opposite said connector-end for
`optically and electrically connecting said optical
`fiber and said electrical conductor to one of a plu-
`rality of photoplethysmographic measurement sys-
`tems; and
`a meansfor identifying a characteristic of the probe
`apparatus to said photoplethysmographic system.
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`17. The probe apparatus of claim 16, wherein the char-
`acteristic of the probe apparatus is selected from the group
`consisting of probe type, photoplethysmographic system
`manufacturer and photodetector type.
`18. The probe apparatus of claim 16, wherein the identi-
`fication means comprises one or more electrical elements.
`19. The probe apparatus of claim 18, wherein the identi-
`ficatio