`(12) Patent Application Publication (10) Pub. No.: US 2003/0181798 A1
`Al-Ali
`(43) Pub. Date:
`Sep. 25, 2003
`
`US 20030181798A1
`
`(54) PHYSIOLOGICAL MEASUREMENT
`COMMUNICATIONS ADAPTER
`
`(52) U.S. Cl.
`
`............................................................ .. 600/324
`
`(76)
`
`Inventor: Ammar Al-Ali, Tustin, CA (US)
`
`Correspondence Address:
`KNOBBE MARTENS OLSON & BEAR LLP
`2040 MAIN STREET
`FOURTEENTH FLOOR
`IRVINE, CA 92614 (US)
`
`(21) Appl' No’:
`(22)
`Filed:
`
`10/377933
`Feb_ 28, 2003
`
`Related U_S_ Application Data
`
`(60) Provisional application No. 60/367,428, filed on Mar.
`25, 2002.
`
`Publication Classification
`
`(51)
`
`Int. Cl.7 ..................................................... .. A61B 5/00
`
`57
`
`ABSTRACT
`
`)
`(
`Asensor interface is configured to receive a sensor signal. A
`transmitter modulates a first baseband signal responsive to
`the sensor signal so as to generate a transmit signal. A
`receiver demodulates a receive signal corresponding to the
`transmit signal so as to generate a second baseband signal
`corresponding to the first baseband signal. Further, a monitor
`interface is configured to communicate a Waveform respon-
`sive to the second baseband signal to a sensor port of a
`monitor. The Waveform is adapted. to the monitor so that
`measurements derived by the monitor from the Waveform
`are generally equivalent to measurements derivable from the
`sensor signal. The communications adapter may further
`Comprise 3 Signal Pr0Ce550r haViHg an input in C0H1m11Hi'
`cations with the sensor interface, Where the signal processor
`is operable to derive a parameter responsive to the sensor
`signal and Where the first baseband signal is responsive to
`the parameter. The parameter may correspond to at least one
`of a measured oxygen saturation and a pulse rate.
`
`V/* 300
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`U.S. Pat. No. 8,923,941
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`Patent Application Publication
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`Sep. 25, 2003 Sheet 1 of 17
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`US 2003/0181798 A1
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`US 2003/0181798 A1
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`Sep. 25, 2003
`
`PHYSIOLOGICAL MEASUREMENT
`COMMUNICATIONS ADAPTER
`
`REFERENCE TO RELATED APPLICATION
`
`[0001] The present application claims priority benefit
`under 35 U.S.C. §119(e) from U.S. Provisional Application
`No. 60/367,428, filed Mar. 25, 2002, entitled “Physiological
`Measurement Communications Adapter,” which is incorpo-
`rated herein by reference.
`
`BACKGROUND OF THE INVENTION
`
`[0002] Patient vital sign monitoring may include measure-
`ments of blood oxygen, blood pressure, respiratory gas, and
`EKG among other parameters. Each of these physiological
`parameters typically require a sensor in contact with a
`patient and a cable connecting the sensor to a monitoring
`device. For example, FIGS. 1-2 illustrate a conventional
`pulse oximetry system 100 used for the measurement of
`blood oxygen. As shown in FIG. 1, a pulse oximetry system
`has a sensor 110, a patient cable 140 and a monitor 160. The
`sensor 110 is typically attached to a finger 10 as shown. The
`sensor 110 has a plug 118 that inserts into a patient cable
`socket 142. The monitor 160 has a socket 162 that accepts
`a patient cable plug 144. The patient cable 140 transmits an
`LED drive signal 252 (FIG. 2) from the monitor 160 to the
`sensor 110 and a resulting detector signal 254 (FIG. 2) from
`the sensor 110 to the monitor 160. The monitor 160 pro-
`cesses the detector signal 254 (FIG. 2) to provide, typically,
`a numerical readout of the patient’s oxygen saturation, a
`numerical readout of pulse rate, and an audible indicator or
`“beep” that occurs in response to each arterial pulse.
`
`[0003] As shown in FIG. 2, the sensor 110 has both red
`and infrared LED emitters 212 and a photodiode detector
`214. The monitor 160 has a sensor interface 271, a signal
`processor 273, a controller 275, output drivers 276, a display
`and audible indicator 278, and a keypad 279. The monitor
`160 determines oxygen saturation by computing the differ-
`ential absorption by arterial blood of the two wavelengths
`emitted by the sensor emitters 212, as is well-known in the
`art. The sensor interface 271 provides LED drive current 252
`which alternately activates the red and IR LED emitters 212.
`The photodiode detector 214 generates a signal 254 corre-
`sponding to the red and infrared light energy attenuated from
`transmission through the patient finger 10 (FIG. 1). The
`sensor interface 271 also has input circuitry for amplifica-
`tion, filtering and digitization of the detector signal 254. The
`signal processor 273 calculates a ratio of detected red and
`infrared intensities, and an arterial oxygen saturation value
`is empirically determined based on that ratio. The controller
`275 provides hardware and software interfaces for managing
`the display and audible indicator 278 and keypad 279. The
`display and audible indicator 278 shows the computed
`oxygen status, as described above, and provides the pulse
`beep as well as alarms indicating oxygen desaturation
`events. The keypad 279 provides a user interface for setting
`alarm thresholds, alarm enablement, and display options, to
`name a few.
`
`SUMMARY OF THE INVENTION
`
`[0004] Conventional physiological measurement systems
`are limited by the patient cable connection between sensor
`and monitor. A patient must be located in the immediate
`
`vicinity of the monitor. Also, patient relocation requires
`either disconnection of monitoring equipment and a corre-
`sponding loss of measurements or an awkward simultaneous
`movement of patient equipment and cables. Various devices
`have been proposed or implemented to provide wireless
`communication links between sensors and monitors, freeing
`patients from the patient cable tether. These devices, how-
`ever, are incapable of working with the large installed base
`of existing monitors and sensors, requiring caregivers and
`medical institutions to suffer expensive wireless upgrades. It
`is desirable, therefore, to provide a communications adapter
`that
`is plug-compatible both with existing sensors and
`monitors and that implements a wireless link replacement
`for the patient cable.
`
`[0005] An aspect of a physiological measurement com-
`munications adapter comprises a sensor interface configured
`to receive a sensor signal. A transmitter modulates a first
`baseband signal responsive to the sensor signal so as to
`generate a transmit signal. Areceiver demodulates a receive
`signal corresponding to the transmit signal so as to generate
`a second baseband signal corresponding to the first baseband
`signal. Further, a monitor interface is configured to commu-
`nicate a waveform responsive to the second baseband signal
`to a sensor port of a monitor. The waveform is adapted to the
`monitor so that measurements derived by the monitor from
`the waveform are generally equivalent
`to measurements
`derivable from the sensor signal. The communications
`adapter may further comprise a signal processor having an
`input in communications with the sensor interface, where
`the signal processor is operable to derive a parameter
`responsive to the sensor signal and where the first baseband
`signal is responsive to the parameter. The parameter may
`correspond to at least one of a measured oxygen saturation
`and a pulse rate.
`
`[0006] One embodiment may further comprise a wave-
`form generator that synthesizes the waveform from a pre-
`determined shape. The waveform generator synthesizes the
`waveform at a frequency adjusted to be generally equivalent
`to the pulse rate. The waveform may have a first amplitude
`and a second amplitude, and the waveform generator may be
`configured to adjusted the amplitudes so that measurements
`derived by the monitor are generally equivalent to a mea-
`sured oxygen saturation.
`
`the sensor interface is
`In another embodiment,
`[0007]
`operable on the sensor signal to provide a plethysmograph
`signal output, where the first baseband signal is responsive
`to the plethysmograph signal. This embodiment may further
`comprise a waveform modulator that modifies a decoded
`signal responsive to the second baseband signal to provide
`the waveform. The waveform modulator may comprise a
`demodulator that separates a first signal and a second signal
`from the decoded signal, an amplifier that adjusts amplitudes
`of the first and second signals to generate a first adjusted
`signal and a second adjusted signal, and a modulator that
`combines the first and second adjusted signals into the
`waveform. The amplitudes of the first and second signals
`may be responsive to predetermined calibration data for the
`sensor and the monitor.
`
`[0008] An aspect of a physiological measurement com-
`munications adapter method comprises the steps of inputting
`a sensor signal at a patient location, communicating patient
`data derived from the sensor signal between the patient
`
`0019
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`Sep. 25, 2003
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`location and a monitor location, constructing a waveform at
`the monitor location responsive to the sensor signal, and
`providing the waveform to a monitor via a sensor port. The
`waveform is constructed so that the monitor calculates a
`
`parameter generally equivalent to a measurement derivable
`from the sensor signal.
`
`In one embodiment, the communicating step may
`[0009]
`comprise the substeps of deriving a conditioned signal from
`the sensor signal, calculating a parameter signal from the
`conditioned signal, and transmitting the parameter signal
`from the patient
`location to the monitor location. The
`constructing step may comprise the substep of synthesizing
`the waveform from the parameter signal. In an alternative
`embodiment,
`the communicating step may comprise the
`substeps of deriving a conditioned signal from said sensor
`signal and transmitting the conditioned signal from the
`patient location to the monitor location. The constructing
`step may comprise the substeps of demodulating the con-
`ditioned signal and re-modulating the conditioned signal to
`generate the waveform. The providing step may comprise
`the substeps of inputting a monitor signal from an LED drive
`output of the sensor port, modulating the waveform in
`response to the monitor signal, and outputting the waveform
`on a detector input of the sensor port.
`
`[0010] Another aspect of a physiological measurement
`communications adapter comprises a sensor interface means
`for inputting a sensor signal and outputting a conditioned
`signal, a transmitter means for sending data responsive to the
`sensor signal, and a receiver means for receiving the data.
`The communications adapter further comprises a waveform
`processor means for constructing a waveform from the data
`so that measurements derived by a monitor from the wave-
`form are generally equivalent to measurements derivable
`from the sensor signal, and a monitor interface means for
`communicating the waveform to a sensor port of the moni-
`tor. The communications adapter may further comprise a
`signal processor means for deriving a parameter signal from
`the conditioned signal, where the data comprises the param-
`eter signal. The waveform processor means may comprise a
`means for synthesizing the waveform from the parameter
`signal. The data may comprise the conditioned signal, and
`the waveform processor means may comprise a means for
`modulating the conditioned signal in response to the moni-
`tor.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0011] FIG. 1 is an illustration of a prior art pulse oxim-
`etry system;
`
`[0012] FIG. 2 is a functional block diagram of a prior art
`pulse oximetry system;
`
`[0013] FIG. 3 is an illustration of a physiological mea-
`surement communications adapter;
`
`[0014] FIGS. 4A-B are illustrations of communications
`adapter sensor modules;
`
`[0015] FIGS. 5A-C are illustrations of communications
`adapter monitor modules;
`
`[0016] FIG. 6 is a functional block diagram of a commu-
`nications adapter sensor module;
`
`[0017] FIG. 7 is a functional block diagram of a commu-
`nications adapter monitor module;
`
`[0018] FIG. 8 is a functional block diagram of a sensor
`module configured to transmit measured pulse oximeter
`parameters;
`
`[0019] FIG. 9 is a functional block diagram of a monitor
`module configured to received measured pulse oximeter
`parameters;
`
`[0020] FIG. 10 is a functional block diagram of a sensor
`module configured to transmit a plethysmograph;
`
`[0021] FIG. 11 is a functional block diagram of a monitor
`module configured to receive a plethysmograph;
`
`[0022] FIG. 12 is a functional block diagram of a wave-
`form modulator;
`
`[0023] FIG. 13 is a functional block diagram of a sensor
`module configured for multiple sensors; and
`
`[0024] FIG. 14 is a functional block diagram of a monitor
`module configured for multiple sensors.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT Overview
`
`[0025] FIG. 3 illustrates one embodiment of a communi-
`cations adapter. FIGS. 4-5 illustrate physical configurations
`for a communications adapter. In particular, FIGS. 4A-B
`illustrate sensor module configurations and FIGS. 5A-C
`illustrate monitor module configurations. FIGS. 6-14 illus-
`trate communications adapter functions. In particular, FIGS.
`6-7 illustrate general functions for a sensor module and a
`monitor module, respectively. FIGS. 8-9 functionally illus-
`trate a communications adapter where derived pulse oxim-
`etry parameters, such as saturation and pulse rate are trans-
`mitted between a sensor module and a monitor module.
`
`Also, FIGS. 10-12 functionally illustrate a communications
`adapter where a plethysmograph is transmitted between a
`sensor module and a monitor module. FIGS. 13-14 func-
`
`tionally illustrate a multiple-parameter communications
`adapter.
`
`[0026] FIG. 3 illustrates a communications adapter 300
`having a sensor module 400 and a monitor module 500. The
`communications adapter 300 communicates patient data
`derived from a sensor 310 between the sensor module 400,
`which is located proximate a patient 20 and the monitor
`module 500, which is located proximate a monitor 360. A
`wireless link 340 is provided between the sensor module 400
`and the monitor module 500, replacing the conventional
`patient cable, such as a pulse oximetry patient cable 140
`(FIG. 1). Advantageously, the sensor module 400 is plug-
`compatible with a conventional sensor 310. In particular, the
`sensor connector 318 connects to the sensor module 400 in
`
`a similar manner as to a patient cable. Further, the sensor
`module 400 outputs a drive signal to the sensor 310 and
`inputs a sensor signal from the sensor 310 in an equivalent
`manner as a conventional monitor 360. The sensor module
`
`400 may be battery powered or externally powered. External
`power may be for recharging internal batteries or for pow-
`ering the sensor module during operation or both.
`
`[0027] As shown in FIG. 3, the monitor module 500 is
`advantageously plug-compatible with a conventional moni-
`tor 360. In particular, the monitor’s sensor port 362 connects
`to the monitor module 500 in a similar manner as to a patient
`cable, such as a pulse oximetry patient cable 140 (FIG. 1).
`Further, the monitor module 500 inputs a drive signal from
`
`0020
`
`0020
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`US 2003/0181798 A1
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`Sep. 25, 2003
`
`the monitor 360 and outputs a corresponding sensor signal
`to the monitor 360 in an equivalent manner as a conventional
`sensor 310. As such, the combination sensor module 400 and
`monitor module 500 provide a plug-compatible wireless
`replacement for a patient cable, adapting an existing wired
`physiological measurement system into a wireless physi-
`ological measurement system. The monitor module 500 may
`be battery powered, powered from the monitor, such as by
`tapping current from a monitor’s LED drive, or externally
`powered from an independent AC or DC power source.
`
`adapter 300 is
`communications
`[0028] Although a
`described herein with respect to a pulse oximetry sensor and
`monitor, one of ordinary skill in the art will recognize that
`a communications adapter may provide a plug-compatible
`wireless replace for a patient cable that connects any physi-
`ological sensor and corresponding monitor. For example, a
`communications adapter 300 may be applied to a biopoten-
`tial sensor, a non-invasive blood pressure (NIBP) sensor, a
`respiratory rate sensor, a glucose sensor and the correspond-
`ing monitors, to name a few.
`
`[0029] Sensor Module Physical Configurations
`
`[0030] FIGS. 4A-B illustrate physical embodiments of a
`sensor module 400. FIG. 4A illustrates a wrist-mounted
`
`module 410 having a wrist strap 411, a case 412 and an
`auxiliary cable 420. The case 412 contains the sensor
`module electronics, which are functionally described with
`respect to FIG. 6, below. The case 412 is mounted to the
`wrist strap 411, which attaches the wrist-mounted module
`410 to a patient 20. The auxiliary cable 420 mates to a sensor
`connector 318 and a module connector 414, providing a
`wired link between a conventional sensor 310 and the
`
`the auxiliary
`wrist-mounted module 410. Alternatively,
`cable 420 is directly wired to the sensor module 400. The
`wrist-mounted module 410 may have a display 415 that
`shows sensor measurements, module status and other visual
`indicators, such as monitor status. The wrist-mounted mod-
`ule 410 may also have keys (not shown) or other input
`mechanisms to control its operational mode and character-
`istics. In an alternative embodiment, the sensor 310 may
`have a tail (not shown) that connects directly to the wrist-
`mounted module 410, eliminating the auxiliary cable 420.
`
`[0031] FIG. 4B illustrates a clip-on module 460 having a
`clip 461, a case 462 and an auxiliary cable 470. The clip 461
`attaches the clip-on module 460 to patient clothing or
`objects near a patient 20, such as a bed frame. The auxiliary
`cable 470 mates to the sensor connector 318 and functions
`
`as for the auxiliary cable 420 (FIG. 4A) of the wrist-
`mounted module 410 (FIG. 4A), described above. The
`clip-on module 460 may have a display 463 and keys 464 as
`for the wrist-mounted module 410 (FIG. 4A). Either the
`wrist-mounted module 410 or the clip-on module 460 may
`have other input or output ports (not shown) that download
`software, configure the module, or provide a wired connec-
`tion to other measurement
`instruments or computing
`devices, to name a few examples.
`
`[0032] Monitor Module Physical Configurations
`
`[0033] FIGS. 5A-C illustrate physical embodiments of a
`monitor module 500. FIG. 5A illustrates a direct-connect
`
`module 510 having a case 512 and an integrated monitor
`connector 514. The case 512 contains the monitor module
`
`electronics, which are functionally described with respect to
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`FIG. 7, below. The monitor connector 514 mimics that of
`the monitor end of a patient cable, such as a pulse oximetry
`patient cable 140 (FIG. 1), and electrically and mechani-
`cally connects the monitor module 510 to the monitor 360
`via the monitor’s sensor port 362.
`
`[0034] FIG. 5B illustrates a cable-connect module 540
`having a case 542 and an auxiliary cable 550. The case 542
`functions as for the direct-connect module 510 (FIG. 5A),
`described above. Instead of directly plugging into the moni-
`tor 360, the cable-connect module 540 utilizes the auxiliary
`cable 550, which mimics the monitor end of a patient cable,
`such as a pulse oximetry patient cable 140 (FIG. 1), and
`electrically connects the cable-connect module 540 to the
`monitor sensor port 362.
`
`[0035] FIG. 5C illustrates a plug-in module 570 having a
`plug-in case 572 and an auxiliary cable 580. The plug-in
`case 572 is mechanically compatible with the plug-in chassis
`of a multiparameter monitor 370 and may or may not
`electrically connect to the chassis backplane. The auxiliary
`cable 580 mimics a patient cable and electrically connects
`the plug-in module 570 to the sensor port 372 of another
`plug-in device. Adirect-connect module 510 (FIG. 5A) or a
`cable-connect module 540 (FIG. 5B) may also be used with
`a multiparameter monitor 370.
`
`In a multiparameter embodiment, such as described
`[0036]
`with respect to FIGS. 13-14, below, a monitor module 500
`may connect to multiple plug-in devices of a multiparameter
`monitor 370. For example, a cable-connect module 540
`(FIG. 5B) may have multiple auxiliary cables 550 (FIG.
`5B) that connect to multiple plug-in devices installed within
`a multiparameter monitor chassis. Similarly, a plug-in mod-
`ule 570 may have one or more auxiliary cables 580 with
`multiple connectors for attaching to the sensor ports 372 of
`multiple plug-in devices.
`
`[0037] Communications Adapter Functions
`
`[0038] FIGS. 6-7 illustrate functional embodiments of a
`communications adapter. FIG. 6 illustrates a sensor module
`400 having a sensor interface 610, a signal processor 630, an
`encoder 640, a transmitter 650 and a transmitting antenna
`670. A physiological sensor 310 provides an input sensor
`signal 612 at the sensor connector 318. Depending on the
`sensor 310, the sensor module 400 may provide one or more
`drive signals 618 to the sensor 310. The sensor interface 610
`inputs the sensor signal 612 and outputs a conditioned signal
`614. The conditioned signal 614 may be coupled to the
`transmitter 650 or further processed by a signal processor
`630. If the sensor module configuration utilizes a signal
`processor 630, it derives a parameter signal 632 responsive
`to the sensor signal 612, which is then coupled to the
`transmitter 650. Regardless,
`the transmitter 650 inputs a
`baseband signal 642 that is responsive to the sensor signal
`612. The transmitter 650 modulates the baseband signal 642
`with a carrier to generate a transmit signal 654. The transmit
`signal 654 may be derived by various amplitude, frequency
`or phase modulation schemes, as is well known in the art.
`The transmit signal 654 is coupled to the transmit antenna
`670, which provides wireless communications to a corre-
`sponding receive antenna 770 (FIG. 7), as described below.
`
`the sensor interface 610
`[0039] As shown in FIG. 6,
`conditions and digitizes the sensor signal 612 to generate the
`conditioned signal 614. Sensor signal conditioning may be
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`performed in the analog domain or digital domain or both
`and may include amplification and filtering in the analog
`domain and filtering, buffering and data rate modification in
`the digital domain, to name a few. The resulting conditioned
`signal 614 is responsive to the sensor signal 612 and may be
`used to calculate or derive a parameter signal 632.
`
`[0040] Further shown in FIG. 6, the signal processor 630
`performs signal processing on the conditioned signal 614 to
`generate the parameter signal 632. The signal processing
`may include buffering, digital filtering, smoothing, averag-
`ing, adaptive filtering and frequency transforms to name a
`few. The resulting parameter signal 632 may be a measure-
`ment calculated or derived from the conditioned signal, such
`as oxygen saturation, pulse rate, blood glucose, blood pres-
`sure and EKG to name a few. Also, the parameter signal 632
`may be an intermediate result from which the above-stated
`measurements may be calculated or derived.
`
`[0041] As described above, the sensor interface 610 per-
`forms mixed analog and digital pre-processing of an analog
`sensor signal and provides a digital output signal to the
`signal processor 630. The signal processor 630 then per-
`forms digital post-processing of the front-end processor
`output. In alternative embodiments, the input sensor signal
`612 and the output conditioned signal 614 may be either
`analog or digital, the front-end processing may be purely
`analog or purely digital, and the back-end processing may be
`purely analog or mixed analog or digital.
`
`In addition, FIG. 6 shows an encoder 640, which
`[0042]
`translates a digital word or serial bit stream, for example,
`into the baseband signal 642, as is well-known in the art. The
`baseband signal 642 comprises the symbol stream that
`drives the transmit signal 654 modulation, and may be a
`single signal or multiple related signal components, such as
`in-phase and quadrature signals. The encoder 640 may
`include data compression and redundancy, also well-known
`in the art.
`
`[0043] FIG. 7 illustrates a monitor module 500 having a
`receive antenna 770, a receiver 710, a decoder 720, a
`waveform processor 730 and a monitor interface 750. A
`receive signal 712 is coupled from the receive antenna 770,
`which provides wireless communications to a corresponding
`transmit antenna 670 (FIG. 6), as described above. The
`receiver 710 inputs the receive signal 712, which corre-
`sponds to the transmit signal 654 (FIG. 6). The receiver 710
`demodulates the receive signal to generate a baseband signal
`714. The decoder 720 translates the symbols of the demodu-
`lated baseband signal 714 into a decoded signal 724, such as
`a digital word stream or bit stream. The waveform processor
`730 inputs the decoded signal 724 and generates a con-
`structed signal 732. The monitor interface 750 is configured
`to communicate the constructed signal 732 to a sensor port
`362 of a monitor 360. The monitor 360 may output a sensor
`drive signal 754, which the monitor interface 750 inputs to
`the waveform processor 730 as a monitor drive signal 734.
`The waveform processor 730 may utilize the monitor drive
`signal 734 to generate the constructed signal 732. The
`monitor interface 750 may also provide characterization
`information 758 to the waveform processor 730, relating to
`the monitor 360, the sensor 310 or both, that the waveform
`processor 730 utilizes to generate the constructed signal 732.
`
`from the constructed signal 732 are generally equivalent to
`measurements derivable from the sensor signal 612 (FIG.
`6). Note that the sensor 310 (FIG. 6) may or may not be
`directly compatible with the monitor 360. If the sensor 310
`(FIG. 6) is compatible with the monitor 360, the constructed
`signal 732 is generated so that measurements derived by the
`monitor 360 from the constructed signal 732 are generally
`equivalent (within clinical significance) with those derivable
`directly from the sensor signal 612 (FIG. 6). If the sensor
`310 (FIG. 6) is not compatible with the monitor 360, the
`constructed signal 732 is generated so that measurements
`derived by the monitor 360 from the constructed signal 732
`are generally equivalent to those derivable directly from the
`sensor signal 612 (FIG. 6) using a compatible monitor.
`
`[0045] Wireless Pulse Oximetry
`
`[0046] FIGS. 8-11 illustrate pulse oximeter embodiments
`of a communications adapter. FIGS. 8-9 illustrate a sensor
`module and a monitor module, respectively, configured to
`communicate measured pulse oximeter parameters. FIG.
`10-11 illustrate a sensor module and a monitor module,
`respectively, configured to communicate a plethysmograph
`signal.
`
`[0047] Parameter Transmission
`
`[0048] FIG. 8 illustrates a pulse oximetry sensor module
`800 having a sensor interface 810, signal processor 830,
`encoder 840, transmitter 850, transmitting antenna 870 and
`controller 890. The sensor interface 810, signal processor
`830 and controller 890 function as described with respect to
`FIG. 2, above. The sensor interface 810 communicates with
`a standard pulse oximetry sensor 310, providing an LED
`drive signal 818 to the LED emitters 312 and receiving a
`sensor signal 812 from the detector 314 in response. The
`sensor interface 810 provides front-end processing of the
`sensor signal 812, also described above, providing a plethys-
`mograph signal 814 to the signal processor 830. The signal
`processor 830 then derives a parameter signal 832 that
`comprises a real time measurement of oxygen saturation and
`pulse rate. The parameter signal 832 may include other
`parameters, such as measurements of perfusion index and
`signal quality. In one embodiment, the signal processor is an
`MS-5 or MS-7 board available from Masimo Corporation,
`Irvine, Calif.
`
`[0049] As shown in FIG. 8, the encoder 840, the trans-
`mitter 850 and the transmitting antenna 870 function as
`described with respect to FIG. 6, above. For example, the
`parameter signal 832 may be a digital word stream that is
`serialized into a bit stream and encoded into a baseband
`
`signal 842. The baseband signal 842 may be, for example,
`two bit symbols that drive a quadrature phase shift keyed
`(QPSK) modulator in the transmitter 850. Other encodings
`and modulations are also applicable, as described above.
`The transmitter 850 inputs the baseband signal 842 and
`generates a transmit signal 854 that is a modulated carrier
`having a frequency suitable for short-range transmission,
`such as within a hospital room, doctor’s office, emergency
`vehicle or critical care ward, to name a few. The transmit
`signal 854 is coupled to the transmit antenna 870, which
`provides wireless communications
`to a corresponding
`receive antenna 970 (FIG. 9), as described below.
`
`[0044] The constructed signal 732 is adapted to the moni-
`tor 360 so that measurements derived by the monitor 360
`
`[0050] FIG. 9 illustrates a monitor module 900 having a
`receive antenna 970, a receiver 910, a decoder 920, a
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`waveform generator 930 and an interface cable 950. The
`receive antenna 970, receiver 910 and decoder 920 function
`as described with respect to FIG. 7, above. In particular, the
`receive signal 912 is coupled from the receive antenna 970,
`which provides wireless communications to a corresponding
`transmit antenna 870 (FIG