US20050148883A1 - Wireless sensing device and method with capability of short range radio frequency transmissions - Google Patents

Abstract

A device and a method of sensing and transmitting physiological pressures and body temperatures are disclosed. The device includes a transducer and a transmitter. The transmitter is adapted to broadcast a signal which is modulated by the output of a transducer. The transmitter is also adapted to limit the power of the output signal. The method includes transducing a physiological parameter and broadcasting a signal which is modulated by the transduced parameter. The power of the output signal is limited so that the signal will attenuate within a predetermined distance.

Description

BACKGROUND OF THE INVENTION
• A. Field of the Invention
• The present invention relates to biological pressure sensors. More particularly, though not exclusively, the present invention relates to sensors, such as a stethoscope, wherein a physiological pressure is sensed or transduced and the transduced pressure is used to modulate a transmitted signal.
• B. Problems in the Art
• Physiological pressure transducers are known in the art. For example, both stethoscopes and sphygmomanometers are known. Conventional transducers are utilized by applying the transducer to the patient and contemporaneously listening to the output or reading the output from a display.
• Even though pressure transducers are known, there are not any known devices which function together with a transducer to make long term recordings of a transduced pressure, such as heart or lung sounds (pressure waves). It would be desirable to make long term recordings of physiological pressures for a number of different reasons.
• First, recordings of sounds/pressures allows for more accurate diagnoses and for the greater use of second opinions. In conventional practice, a doctor will apply a stethoscope to a patient and arrive at a conclusion based on the sounds perceived by the doctor. To receive a second opinion, many times another doctor will be able to apply a stethoscope and hear the same sounds. However, for those sounds which are not repetitive, a second doctor must rely on the first doctor to verbally describe the sound perceived by the first doctor. If the second doctor were able to observe a recording of the sound perceived by the first doctor, a better second opinion could be utilized.
• In addition, it is desirable to make long term recordings of physiological sounds and pressures to limit medical malpractice liability. For example, it would be easier for a doctor to prove he complied with the standard of care required for the situation by explaining how the doctor made a decision in light of the sound that was actually heard by the doctor. Rather than having to rely on the doctor's oral representation as to what sound was perceived, a fact finder would have the actual sound in front of it, making for a more reliable truth seeking process. There is a need in the art for a method which allows for long term recordings of physiological pressures.
• One possible method of making long term measurements of physiological pressures is to connect a pressure transducer to a display or recording device through wire connections. However, wire connections can create additional hazards. For example, wire connections could lead to the possibility of the transducer being disconnected from the recording device by someone tripping over the connection. In addition, wire connections create additional problems when a patient must be moved quickly from one part of the hospital to another. Either the pressure sensor must be removed from the patient, taking additional time, or the monitor or recording device must be moved along with the patient, also requiring additional time and hospital personnel to move the recording device.
• One method of dealing with the problems caused by wire connections is to utilize wireless communications between the stethoscope or other transducer and the display device. However, as wireless devices proliferate, there is an increasing probability that an output from a first device will cause electromagnetic interference with a second device. In those hospital rooms that house multiple patients, there is an even greater likelihood that wireless devices will cause interference. This is of particular concern when the devices that are interfered with control some vital function of a patient, such as a ventilator.
• A wireless stethoscope is known in the art. However, none of the known stethoscopes limit electromagnetic interference by limiting the power of an output signal. Prior art wireless stethoscope utilize high power output signals which increases the probability of electromagnetic interference between devices that are in close proximity. In addition to causing potential interference, the use of a high power output signal exposes a patient to higher intensity electromagnetic fields. Exposure to electromagnetic fields has been linked with possible long term health problems. Also, the use of a high power output signal leads to quicker battery discharge when batteries are used to power the wireless stethoscopes. Finally, the use of higher power output signals increase multipath problems.
• Therefore, it is a primary objective of the present invention to provide a wireless physiological pressure sensor with a transmitter and receiver having the capability of short range radio frequency transmissions which solves problems and deficiencies in the art.
• It is a further object of the present invention to provide a physiological pressure sensing method and device which can communicate a sensed pressure through the use of radio frequency communication.
• It is a further object of the present invention to provide a wireless pressure transducer and transmitter which minimizes the possibility of electromagnetic interference.
• Yet another object of the present invention is to provide a method and device which minimizes a patient's exposure to electromagnetic fields.
• It is a further object of the present invention to provide a device and method which minimize battery drain.
• It is a further object of the present invention to provide a device and method which minimizes multipath errors.
• These, as well as other objects and features of the present invention, will be apparent from the following detailed description and claims in conjunction with the accompanying drawings.
SUMMARY OF THE INVENTION
• The present invention includes a device for monitoring and wirelessly transmitting a physiological pressure. The device includes a pressure transducer and a transmitter which is in operative communication with the transducer. The transmitter is adapted to broadcast a signal which is modulated by a transduced pressure. The transmitter is also adapted to limit the power of the signal so that the signal attenuates within a predetermined distance from the transmitter. Optionally, the invention may also include a receiver which receives a signal broadcast by the transmitter.
• The present invention can also include a method of monitoring and transmitting a physiological pressure. The method includes the steps of transducing the pressure and broadcasting a signal which is modulated by the transduced pressure. The method also includes the step of limiting the power of the broadcast signal so that the signal attenuates within a predetermined distance. The method can optionally include additional steps such as receiving the broadcast signal, recovering the pressure/sound from the received signal, and storing the measurement in a digital record.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a bottom plan view of an embodiment of a wireless stethoscope according to the present invention.
• FIG. 2 is a top plan view of the stethoscope ofFIG. 1.
• FIG. 3 is a side elevational view of the stethoscope ofFIG. 1.
• FIG. 4 is a schematic diagram which illustrates the limited range transmission according to an aspect of the present invention.
• FIG. 5 is a block diagram which illustrates an embodiment of a pressure transducing system according to the present invention.
• FIG. 6 is a pictorial view showing a user wearing a receiver and transmitter system.
• FIG. 7 is a perspective view of the ear piece unit of the receiver and transmitter system ofFIG. 6.
• FIG. 8 is a cross-sectional view of the ear piece unit ofFIG. 7 taken through the external auditory canal of the user.
DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT
• The present invention will be described as it applies to its preferred embodiment. It is not intended that the present invention be limited to the described embodiment. It is intended that the invention cover all modifications and alternatives which may be included within the spirit and scope of the invention.
• FIG. 1 shows a bottom plan view of awireless stethoscope10 according to an embodiment of the present invention.Stethoscope10 includes adiaphragm12 and abell14.Diaphragm12 is conventional.Diaphragm12 is preferably comprised of plastic and operates in conjunction with a microphone to transduce sound waves into electrical signals. Any material which can transduce sound (or other physiological pressure) into an electric or magnetic signal, such as a piezoelectric material, could be used.Bell14 is a conventional stethoscope bell.
• Atemperature sensor15 and aheart rate sensor17 may be included.Temperature sensor15 andheart rate sensor17 are conventional. A patient's temperature or heart rate may be displayed on LCD18 (FIG. 2).
• FIG. 2 shows a top plan view ofstethoscope10.Stethoscope10 has adual detent button16. A first push or click ofbutton16 will causestethoscope10 to broadcast a signal (explained more fully later on). A second push ofbutton16 causes stethoscope10 to record a transduced sound onto a memory chip located insidestethoscope10.Stethoscope10 can broadcast a signal while also recording a transduced sound.
• A liquid crystal display (LCD)18 is also included withstethoscope10.LCD18 can display patient information, such as a patient's heart rate or temperature.LCD18 may also have icons to display the operating mode ofstethoscope10, e.g., whetherstethoscope10 is transmitting23 and/or recording.
• Stethoscope10 includes buttons for thebell20, thetemperature22, and theheart rate24. Thesebuttons20,22,24 serve as switches. In the default mode of operation,stethoscope10 will transmit a signal which is modulated by the output ofdiaphragm12. By pushing one of the buttons, thestethoscope10 will broadcast a signal which is modulated by the output ofbell14,temperature sensor15, orheart rate sensor17, depending on which button is selected.
• It will be apparent to those skilled in the art that the transmitter could transmit a signal from which any of the sensed parameters (e.g., heart rate or sound) could be recovered. For example, the transmitter could be adapted so that it outputs a digital signal that contains the various sensed parameters at different locations on the signal. The various sensed parameters could then be recovered by a receiver using signal processing techniques that are known in the art. In addition, the transmitter could have a plurality of antennas to transmit different signals corresponding to the sensed parameters. However, for sake of simplicity and cost, the transmitter will usually be designed such that only one parameter or variable is contained in the broadcast signal.
• Stethoscope10 is battery operated.Stethoscope10 includes a battery recharging port/battery access panel21. The rechargingport21 is conventional. The cover panel on rechargingport21 can be removed to allow for a change of batteries.
• FIG. 3 shows a side view of thewireless stethoscope10.FIG. 3 shows theantenna26 in hidden lines. Theantenna26 is housed withinstethoscope10. Of course, theantenna26 could be external.Antenna26 is conventional.
• Returning toFIG. 1,diaphragm12 is an operative communication with a transmitter circuit insidestethoscope10. The transmitter circuit includes anantenna26. The transmitter circuit is adapted to broadcast a signal which is modulated by the output ofdiaphragm12. A receiver can be provided which can recover the sounds from the broadcast signal.
• Preferably, the power of the broadcast signal is limited so that the signal will attenuate within a predetermined distance from the transmitter.FIG. 4 shows a schematic representation of this scheme. For a hospital setting, the transmission radius is preferably 15 feet or less, with 10 feet being ideal.
• The actual power of the broadcast signal will depend on a number of factors, such as the frequency of the signal, the distance in which the signal should attenuate, the temperature and humidity of the environment in which the signal is broadcast, etc. The broadcast signal is preferably a radio frequency signal at about either 900 MHz or 2.4 GHz, as these two frequencies are still open to the public. Preferably, the broadcast signal is a digital spread spectrum signal. It will be apparent to those skilled in the art that there are many ways to generate the broadcast signal, and many different modulation techniques could be utilized.
• As noted earlier, selecting one of the switches orbuttons20,22,24 (FIG. 2) will place the output of the sensor in operative communication with the transmitter. The output signal of the transmitter will then be modulated by the output of the corresponding sensor.
• It should be noted thatstethoscope10 could also include a receiver. There may be times when it is desirable to havestethoscope10 receive instructions from a remote transmitter. For example,stethoscope10 could be configured to receive instructions from a computer that is part of a wireless computer network, or from some other transmitter. The computer may transmit instructions to stethoscope to tellstethoscope10 to perform a function, such as begin transmitting or turn the power off.
• By limiting the output power of the broadcast signal,wireless stethoscope10 will consume less power. For a battery-powered stethoscope, the batteries will have to be recharged or changed less frequently. Also, the intensity of the broadcast signal is smaller, exposing a patient to minimal electromagnetic radiation. Since the broadcast signal attenuates within a predetermined distance from the transmitter, there is a decreased probability that devices outside the transmission radius (FIG. 4) will suffer from electromagnetic interference. In addition, a receiver will not suffer from as many multipath problems because there is less chance that a reflected signal will reach the receiver.
• Rather than using a stethoscope as a pressure transducer, a sphygmomanometer could be used. The sphygmomanometer includes a transmitter in operative communication with an output of the sphygmomanometer. The transmitter broadcasts a signal which is modulated by the output of the sphygmomanometer. As previously described, the power of the broadcast signal is limited so that the signal will attenuate within a predetermined distance from the transmitter.
• FIG. 5 shows a block diagram of apressure transducing system40 according to the present invention. Thesystem40 includes a transducer42 (either a pressure transducer or a thermal transducer). Theoutput44 of thetransducer42 is input into atransmitter46.Transmitter46 broadcasts asignal48 which is received by thereceiver50.Receiver50 can be adapted to recover a transduced pressure from thebroadcast signal48, using signal processing techniques that are known in the art.
• In addition,receiver50 could have an analog-to-digital converter which could digitize a recovered pressure. This digitized version could be conveyed to adigital computer52 or could be written to a digital storage medium, such as a compact disc. Note that with the availability of large scale digital storage mediums, long term recordings of pressures, in excess of 24 hours, could be made. This could be important in proving that there was no indication of imminent danger in those unfortunate cases where a patient dies while being monitored. This may help prevent frivolous medical malpractice litigation.
• As noted earlier, there could be a second receiver in operative communication with thetransducer42 or thetransmitter46. For example,computer52 could have a transmitter and could output signals to a second receiver. The second receiver could in turn “instruct” thetransducer42 or transmitter to perform a function, such as begin transmitting or operate in standby mode.
• The physiological pressure sensor and transmitter combination of the present invention is particularly well suited to communicate with a receiver having a bone conduction sensor, an air conduction sensor, or both and also with a transceiver. Such devices are disclosed in co-pending U.S. Ser. No. 09/309,107, filed May 10, 1999, and U.S. Ser. No. 09/416,168, filed Oct. 11, 1999, the disclosures of which are hereby incorporated by reference in their entirety.
• FIG. 6 illustrates a receiver andtransmitter system70 as worn by a user. The user wears theear piece72 and thetransceiver unit74. Thetransceiver unit74 may be worn on the user'sbelt76, though it is also possible to store thetransceiver unit74 in a number of other areas which may be convenient for the user, such as a shirt pocket, coat pocket, or vest pocket.
• As seen inFIG. 7, theear piece72 includes an externalear canal portion80 having abone conduction sensor82 in contact with the external auditory canal epithelium of the user, an air conduction sensor ormicrophone85, and aspeaker84. Acasing86 is also provided, having anear attachment portion88 and afitting portion90 that connects theear attachment portion88 with thebone conduction sensor82, theair conduction sensor85, andspeaker84. Theear attachment portion88 is contoured to comfortably fit into the angle between the ear auricle and the temporal bone of the skull of the user and is preferably made of a lightweight aluminum or plastic material. It can be appreciated that the primary purpose of theear attachment portion88 is to secure theear piece72 in proper position. Thefitting portion90 is integral with theear attachment portion88 and is reinforced with a flexible wire so that theear piece72 may be adapted to fit the user and maintain thebone conduction sensor82 and theair conduction sensor85 in their proper positions with the externalauditory canal94 of the user.
• As is best shown inFIG. 8, theear piece72 should be fit so that thebone conduction sensor82 is in contact with a portion of the externalauditory canal94 near the bony-cartilaginous junction. It is preferred that thebone conduction sensor82 rest against the posterior superior wall of the externalauditory canal94, with the flexible wire of thefitting portion90 shaped to bias thebone conduction sensor82 into position. Fitting the device and calibrations may be performed by the user or with the assistance of a physician or an audiologist/audiology technician.
• The externalear canal portion80 is formed so that thebone conduction sensor82 may be inserted into the externalauditory canal94 of the user and nonocclusively contact against the posterior superior wall of the bony canal. Thebone conduction sensor82 is intended to pick up, as the voice signals, the vibrations of the upper wall of the externalauditory canal94 at the time of uttering the voice sounds. When the user utters voice sounds, these sounds reach the mastoid bones. These sound vibrations in the external auditory canal portion in contact with thebone sensor82 are then processed.
• In addition to thebone conduction sensor82, the externalear canal portion80 also includes an air conduction sensor ormicrophone85. Like thebone conduction sensor82, theair conduction sensor85 is of standard construction and may be obtained from various hearing aid manufacturers.
• Aresilient member96 is preferably positioned between theair conduction sensor85 and thebone conduction sensor82 in such a manner that the external sound collected by theair conduction sensor85 will not be transmitted to thebone conduction sensor82. Additionally, theinner ear portion80 also includes aspeaker84. Thespeaker84 is of a type well known in the art and common in the hearing aid industry. Thespeaker84 is positioned directly in line with the tympanic membrane to facilitate clear transmissions while maintaining a low power output.
• Acircuit portion98 transmits the electrical signals from both thebone conduction sensor82 and theair conduction sensor85 to aspeech processor100. Thebone conduction sensor82 and theair conduction sensor85 are both tuned to receive frequencies within the range of audible human speech, approximately 50 to 8000 Hertz.
• Thespeech processor100 is of a conventional construction used in many hearing aids and employs a digital processing scheme to package the voice signal for transmission across a wireless linkage. Thespeech processor100 will be programmed to extract similarities from air and bone transmission, comparing the similarities in signal and then transmitting via a wireless linkage to a cellular telephone transceiver or other receiving device. Thespeech processor100 also filters out through band pass filters102 sounds outside the frequency of normal human speech.
• Thespeech processor100 samples a portion of the electrical signals of voice sound information from theair conduction sensor85 and a portion of the electrical signals of voice sound information from thebone conduction sensor82. Thespeech processor100 then transmits the selected voice signal to anear piece transceiver64. Theear piece transceiver64 is preferably a wireless radio frequency transceiver well known in the art which includes a multidirectional antenna112. Theear piece transceiver64 sends the voice signal to thetransceiver unit74. Theear piece transceiver64 also receives incoming signals from thetransceiver unit74 and sends them to thespeaker84.
• Thetransceiver unit74 includes componentry which is common in the art. Thetransceiver unit74 receives the relatively low powered radio frequency (RF) signals from theear piece transceiver64 via an RF local area network antenna, processes the signal, and transmits an amplified RF signal. Further, thetransceiver unit74 receives incoming data through a linkage antenna and transmits this to theear piece transceiver64 using the low powered RF signals. Thetransceiver unit74 may transmit or receive using analog or digital technology.
• Note that this system is particularly advantageous when a doctor is wearing the transceiver andtransmitter system70. The doctor could listen to sounds fromstethoscope10 and make contemporaneous observations. These observations could be transmitted bytransceiver74 ortransceiver64 to a computer. Using the voice recognition techniques disclosed in incorporated U.S. Ser. No. 09/309,107, or other voice recognition techniques, the computer could store the observations in a patient-linked database. Further, because signals fromtransceiver74 ortransceiver64 and fromstethoscope10 can have their own addresses or identifiers, a computer could receive signals from both at the same time. Thus, both the transduced sound (pressure) and the doctor's observations could be recorded together.
• A general description of the present invention as well as a preferred embodiment has been set forth above. Those skilled in the art will recognize and be able to practice additional variations in the methods and devices described which fall within the teachings of this invention. Accordingly, all such modifications and additions are deemed to be within the scope of the invention which is to be limited only by the claims appended hereto.

Claims (12)

1-29. (canceled)

30. A wireless device for monitoring one of a plurality of physiological pressures associated with a patient, comprising:

a housing for protecting the device, the housing having a first planar surface adapted for placement on the patient;

at least one pressure transducer integral with the housing and adapted for placement on the patient;

a transmitter in operative communication with the at least one pressure transducer and operatively connected to the housing, the transmitter adapted to broadcast a signal containing pressure transducer information;

a display secured to the housing and operatively connected to the at least one pressure transducer for displaying a representation of output from the at least one pressure transducer.

31. The wireless device ofclaim 30 further comprising a memory disposed within the housing and operatively connected to at least one pressure transducer for storing an audio representation of the output signal.

32. The wireless device ofclaim 30 wherein the at least one pressure transducer includes a bell portion and a diaphragm portion disposed along said first surface.

33. The wireless device ofclaim 32 further comprising a switch for selecting either an output of the bell or the diaphragm as the output signal.

34. The wireless device ofclaim 30 further comprising a temperature sensor and wherein the display is further adapted to display a representation of output from the temperature sensor.

35. A device for monitoring one of a plurality of physiological pressures associated with a patient, comprising:

a housing for protecting the device, the housing having a first planar surface adapted for placement on the patient;

at least one pressure transducer including a bell portion and a diaphragm portion disposed along said first planar surface.

36. The device ofclaim 35 further comprising a switch for selecting either an output of the bell or the diaphragm as an output signal.

37. The device ofclaim 36 further comprising a display secured to the housing and operatively connected to the at least one pressure transducer for displaying a representation of output from the at least one pressure transducer.

38. The device ofclaim 37 further comprising a pulse sensing transducer, wherein the switch selects the output of the bell portion, the output of the diaphragm portion, or an output of the pulse sensing transducer as the output signal, and wherein the display is further adapted to display a representation of the output from the pulse sensing transducer.

39. The device ofclaim 35 further comprising a transmitter in operative communication with the at least one pressure transducer and disposed with the housing, the transmitter adapted to broadcast a signal containing pressure transducer information.

40. The device ofclaim 35 further comprising a memory disposed within the housing and operatively connected to the at least one pressure transducer for storing an audio representation of an output signal from the at least one pressure transducer.

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