Abstract:
A patient physiological parameter monitoring apparatus for a subject includes a sensor assembly having at least one responsive element that produces a first signal upon detection of a change in temperature. The assembly also includes a converter for converting the first signal into an electrical signal, and a transmitter for wirelessly transmitting converted electrical signals upon demand based upon receipt of a transmitted signal from an interrogation device. Preferably, at least a portion of the sensor assembly is disposable to permit single use or single subject use and can be further used to track location and information of medical equipment in addition to subjects.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation application of a US patent application, entitled WIRELESS DISPOSABLE PHYSIOLOGICAL SENSOR, U.S. Ser. No. 10/702,631, filed Nov. 6, 2003, the entire contents of which are herein incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates generally to the field of diagnostic medicine, and more specifically to medical diagnostic apparatus including a wireless sensor assembly that passively measures the body temperature or other physiological parameter of a subject or relates to a situated diagnostic device for locating either or relation to a device specific characteristic wherein at least a portion of the sensor assembly is disposable. 
       BACKGROUND OF THE INVENTION 
       [0003]    Thermometers are commonly known in the medical field for measuring the core body temperature of a patient. In the majority of these devices, a probe that contains or retains at least one temperature measuring or sensing element, such as a thermocouple or thermistor, is placed at a body site such as the sublingual pocket, or alternately the axillary area, rectal cavity or within the ear canal. The temperature sensing element then either predicts temperature or is caused to remain at the body site until the sensing element reaches the environment temperature after which the probe is either removed for reading by the user or the measured reading is displayed. 
         [0004]    Alternatively, the thermometer can include a resistive or other form of heater used to preheat the temperature sensing element to that which is somewhat closer to the temperature of the body site in order to effectively hasten reading/measurement time. 
         [0005]    In addition to the above wired thermometry devices, there are such as those described in U.S. Pat. Nos. 5,252,962 and 6,054,935 to Urbas et al. that effectively remove the “tether” between the control unit and the probe assembly. To date, such devices are found only for use in certain veterinary applications and only in relation to implantable devices. 
       SUMMARY OF THE INVENTION 
       [0006]    It is therefore a primary object of the present invention to provide a versatile, disposable, low-cost patient temperature or other physiological parameter measuring device. 
         [0007]    It is another primary object of the present invention to provide a wireless physiological parameter measuring device, such as a thermometer, that continually measures patient body temperature and which can be accessed on demand. 
         [0008]    Therefore and according to a preferred aspect of the present invention, there is disclosed an apparatus for measuring at least one physiological parameter of a patient, said apparatus comprising: 
         [0009]    a sensor assembly including at least one physiological parameter responsive element, said responsive element producing a first signal upon detection of a change in physiological parameter, a converter for converting the first signal into an electrical signal, and a transmitter for wirelessly transmitting the converted electrical signal upon demand; and 
         [0010]    an interrogation device having a transmitter that wirelessly transmits a signal to said sensor assembly, wherein said sensor assembly does not transmit readings of said at least one physiological parameter responsive element until the interrogation device transmits the signal, and in which said sensor assembly is disposed on a patient to enable physiological parameters readings to be taken without significant delay, and in which at least a portion of said sensor assembly is disposable. 
         [0011]    Preferably, because at least a portion of the sensor assembly is disposable, it can selectively be dedicated for single use or single patient use and/or can be used a discrete number of times. 
         [0012]    The sensor assembly can include a programmable ASIC that permits information, such as patient or device-related data including demographics including date of birth, insurance carrier information, family medical history, etc., to be stored for subsequent access by the interrogator device to permit this information to track along with the patient, for example, in a hospital or physician&#39;s office encounter. Preferably, the ASIC is attached to a back surface of a disposable sensor assembly wherein at least a portion of the sensor assembly is discarded after patient use, while the ASIC snaps off or is otherwise releasably removed and can be reused. For example, a temperature sensor assembly using the inventive concepts described herein can be made into a flexible assemblage, utilizing technologies, such as silk screening of at least portions thereof, such as the battery, antenna and thermistor, permitting single use or single or multiple patient use. 
         [0013]    The present device is also capable of measuring different physiological parameters including but not limited to blood gas, SPO 2 , blood pressure and heart rate in addition to or in lieu of body temperature. In order to accomplish this objective, various bio-sensors can be attached to the present assembly to permit multiple uses and versatility thereof. Due to the proximity of the sensor assembly to the subject, the device would operate effectively as a monitor and not, for example in the case of body temperature, as a “predict” temperature apparatus. 
         [0014]    The readings obtained by the device can be archived or stored and can be data logged, permitting temperature/pulse and other useful parameter trend data/analysis. 
         [0015]    According to another variant of the invention, a temperature sensor assembly employens the inventive concepts described herein can be disposed within a wraparound disposable apparatus, such as an inflatable blood pressure cuff, that can be wrapped around a limb (e.g., the arm or leg) of a subject. 
         [0016]    Depending upon its construction, the parameter sensor assembly can include multiple parameter responsive elements or can be applied conveniently on different parts of the subject. For example, a pair of temperature sensing assemblies can be attached to a subject to determine thermal variations; for example, the breaking of a limb, a blood clot, or other perceivable problem in an extremely simple and convenient manner. 
         [0017]    In addition, the present device can be further utilized for other applications. For example, the device could be implanted near cancerous tumors and include a sensor enabling same to be able to measure radiation dosages at a specific site. This detection could be used effectively to determine correct dosages of radiation therapy. By its convenience in size, the parameter measuring assembly is not limited to on-the-body measurements, meaning the device can be conveniently attached or implanted, used, as needed, for monitoring purposes and then removed at the end of treatment. 
         [0018]    The herein described measuring apparatus can further be used to monitor stress in vascular and arterial walls on a real-time basis by implantation near glands and be able to measure secretions that are, for example, doped with a tracer element at a specific site. These measurements could be taken before they interact with other fluids or as real-time collection of data, such as, for example, drug delivery and other treatments, or to track subject location. 
         [0019]    According to another preferred aspect of the invention, there is provided a wireless thermometer apparatus for measuring the body temperature of a subject, said thermometer comprising: 
         [0020]    a sensor assembly including at least one temperature responsive element that produces a first signal upon detection of a change in body temperature, a converter for converting the first signal into an electrical signal, and a transmitter for wirelessly transmitting electrical signals upon demand; and 
         [0021]    an interrogation device having a transmitter that wirelessly transmits a signal wherein said sensor assembly does not transmit readings of said at least one temperature responsive element until the interrogation device transmits said signal, and in which said sensor assembly is disposed on a subject to enable temperature readings to be taken without significant delay, wherein at least a portion of said sensor assembly is disposable. 
         [0022]    According to yet another preferred aspect of the present invention, there is disclosed a method for measuring at least one physiological parameter of a subject, said method comprising the steps of: 
         [0023]    attaching a disposable sensor assembly to the body of a subject, said sensor assembly including at least one physiological parameter sensor that is responsive to a trigger signal; 
         [0024]    selectively transmitting a trigger signal in the vicinity of said sensor assembly; 
         [0025]    said sensor assembly transmits a reading from said sensor only in response to reception of said trigger signal and in which at least a portion of said sensor assembly is disposable. 
         [0026]    According to still another preferred aspect of the present invention, there is disclosed a method for identifying the location of medical equipment in a subject&#39;s room, said method including the steps of: 
         [0027]    attaching a sensor assembly to at least one piece of medical equipment, said sensor assembly including a programmable ASIC that includes information concerning said equipment stored therein, a wireless transmitter, a wireless receiver and an antenna for permitting bi-directional wireless communication; 
         [0028]    selectively transmitting a trigger signal from an interrogation device in said subject&#39;s room; and 
         [0029]    transmitting product information from said sensor assembly to said interrogation device only in response to said trigger signal and in which at least a portion of said sensor assembly is disposable. 
         [0030]    As noted, at least a portion of the sensor assembly is disposable and is preferably made from a flexible strip that can be easily attached through adhesive or other means to the equipment for tracking or inventory purposes. This function is useful for billing purposes as well in settling disputes as to whether a price of equipment or procedure was performed on a subject. The function is also useful for traceability and for marrying of physiological data to a piece(s) of equipment, such as but not limited to calibration data. 
         [0031]    The disposability aspect of the present invention provides ease of use for patient application and less risk of cross contamination between subjects or patients. 
         [0032]    One advantage realized by the present invention is that temperature or other physiological parameters can be obtained on demand almost instantaneously. 
         [0033]    Therefore, realizable time savings are achieved by the present measuring apparatus. 
         [0034]    Another advantage provided is that the present assembly is entirely wireless, thereby avoiding cumbersome cables, wires or connectors and providing convenience and versatility for the subject, patient and caregiver. 
         [0035]    Another advantage is that the sensor assembly has relatively low mass as well as high flexibility. The sensor assembly can also be attached to any piece of equipment, such as a vital signs monitor or other device found in a patient&#39;s room, permitting the sensor assembly to be used in order to track the location of apparatus as part of inventory control, or in detecting whether an instrument is present in the patient room using the interrogation device. 
         [0036]    These and other objects, features and advantages will become apparent from the following Detailed Description which should be read in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0037]      FIG. 1  is a perspective view of a physiological parameter measuring apparatus in accordance with a preferred embodiment of the present invention; 
           [0038]      FIG. 2  is a bottom view of a disposable sensor assembly in accordance with a preferred embodiment for use with the physiological parameter measuring apparatus shown according to  FIG. 1 ; 
           [0039]      FIG. 3  is a perspective view of the disposable sensor assembly of  FIG. 2 ; 
           [0040]      FIG. 4  is a bottom view of a disposable sensor assembly in accordance with an other preferred embodiment of the present invention; 
           [0041]      FIG. 5  is a perspective view of the disposable sensor assembly of  FIG. 5 ; 
           [0042]      FIG. 6  depicts a generalized functional schematic diagram of the temperature measuring apparatus of  FIGS. 1-6 ; 
           [0043]      FIG. 7  depicts a top perspective view of an interrogator device in accordance with a preferred embodiment for use with the physiological parameter measuring apparatus of  FIG. 1 ; 
           [0044]      FIG. 8  illustrates an alternate embodiment of the physiological parameter measuring apparatus as used in conjunction with a blood pressure sleeve; 
           [0045]      FIG. 9  depicts an alternate application of the physiological parameter measuring apparatus for use with a patient; 
           [0046]      FIG. 10  is an alternate embodiment of the above measuring apparatus as used for purposes of an equipment inventory or tracking control function; and 
           [0047]      FIG. 11  depicts yet another alternate application of the above measuring apparatus as used with an endoscopic apparatus. 
       
    
    
     DETAILED DESCRIPTION 
       [0048]    The following description relates to certain preferred embodiments and applications of a patient physiological parameter measuring apparatus made in accordance with the present invention. It will be readily apparent to one of sufficient skill in the field, however, that there are modifications and variations that can be implemented within the intended scope of the invention. In addition, and throughout the course of this description, certain terms are used to provide in order to assist the reader and to provide a frame of reference with regard to the accompanying drawings. These terms, however, should not be interpreted as overly limiting to the intended scope of the inventive concept, except where specifically indicated. 
         [0049]    Referring to  FIG. 1 , there is shown a wireless patient monitoring or measuring apparatus  10  made in accordance with a preferred embodiment of the present invention. This wireless monitoring apparatus  10  includes a patient sensor assembly  20  and an interrogation device  30 . The patient sensor assembly  20  is preferably at least partially disposable and is removably attachable to the skin of a subject and can be conveniently applied anywhere thereupon, the sensor assembly including a gel or adhesive pad for permitting direct attachment to the skin. In this instance, the sensor assembly  20  is shown as being attached to the neck area of the patient  34 . As detailed in a later portion, however, it will be shown that the sensor assembly  20  is not limited to merely subject attachment and that there are numerous examples of other varied uses and applications therefor. 
         [0050]    As shown schematically in  FIG. 6 , the sensor assembly  20  according to this embodiment includes at least one element or sensor that is responsive to a physiological parameter. In this embodiment, at least one temperature responsive element  24 , such as a thermistor, thermocouple, or other miniature temperature responsive sensor is provided, the sensor being electronically coupled to low power circuitry that includes analog to digital conversion for converting an electrical signal generated by the temperature responsive element into a digital signal that can be transmitted to the interrogation device  30 . Power for the sensor assembly  20  is created through a passive connection magnetically due to a generated trigger signal from the interrogation device  30 , the sensor assembly including a power generation/power control block. Alternately, the block can be configured to permit active powering of the sensor assembly  20  upon receipt of the trigger signal or that the sensor assembly remains active irrespective of whether a trigger signal is transmitted by the interrogation device. 
         [0051]    The sensor assembly  20  further includes circuitry for routing the digital signal by means of wireless emitter and receive circuitry  32  that permits the processed signal to be transmitted wirelessly by means of an antenna  36  to the interrogation device  30 . Each of the above components are preferably included in the sensor assembly in a patch-like configuration. Examples of specific sensor assemblies are further described herein with reference to  FIGS. 2-5 . 
         [0052]    According to a first embodiment, shown in  FIGS. 2 and 3 , a disposable two piece sensor assembly  50  includes a first disposable supporting portion  54  and a second reusable portion  58 . By “disposable”, it is meant that the portion can be discarded after a single use or after a single patient use and replaced. The first disposable portion  54  of this assembly includes a temperature responsive element  62 , such as a thermistor, that is bonded to a flexible strip  66  having an adhesive backing  70 . Embedded within the flexible strip  66  are leads  74  extending from the temperature responsive element  62  to a pair of connection coupling pads  78 . The reusable section  58  of this assembly  50  includes a body portion  84  that is manufactured from a lightweight plastic material and preferably includes an embedded programmable ASIC  88 , as well as a wireless transmitter/receiver  92  and an antenna  96 , wherein the reusable portion  58  is preferably releasably attached to the top surface  68  of the flexible strip  66 . Preferably, the disposable supporting portion  54  is manufactured using silk screen or other technology. 
         [0053]    According to an alternate embodiment, as shown in  FIGS. 4 and 5 , a second type of sensor assembly  100  in accordance with the invention can be manufactured as a single piece, for preferably either disposable or single subject use. According to this embodiment, the sensor assembly  100  is defined by a flexible substrate  104  that includes a programmable ASIC  108  that is embedded, along with a thermistor  112 , acting as the temperature responsive element, as well as a wireless transmitter  116 , a wireless receiver  120  as well as an antenna  124 , each operatively interconnected. As noted above, other forms of temperature responsive elements can be substituted. In each of these sensor assemblies, unit device or serial information, shown diagrammatically as block  35  in  FIG. 6 , can be stored into the programmable memory of the ASIC  108  such that both parameter data as well as unit/tag information can be transmitted to the interrogation device  30  following reception of the trigger signal by the sensor assembly  100 . 
         [0054]    Referring to  FIGS. 1 ,  6  and  7 , the interrogation device  30  is preferably a hand-held device, such as a PALM-type device or personal data assistant (PDA), that also includes onboard transmit and receive circuitry  38  in the form of a wireless transceiver, in order to enable wireless communication with the sensor assembly  20 , as well as a corresponding antenna  46 . According to the present invention, the form of wireless communication between the sensor assembly  20  and the interrogation device  30  is via RF (radio frequency) generation, though other methods of wireless, communication, including but not limited to optical, ultrasonic, and infrared could similarly be utilized. The interrogation device  30  further includes a user interface  48  that includes a display, such as an LCD  128 , as well as input controls  132  on a facing surface of a device housing  138 , for operating same. For example, threshold alarm limits can be set or programmed by the device whereby readings that exceed a predetermined level will cause an alarm to be triggered. 
         [0055]    Still referring to  FIG. 6 , the interrogation device  30  further includes a miniature processor that includes at least one stored temperature computation algorithm(s) as well as calibration data that is used in conjunction with the readings obtained from the sensor assembly  30 . The processor is interconnected to a serial interface  42  that is connected to the user interface  48 . 
         [0056]    Essential to the operation of the above described assembly, is that the sensor assembly  20  operates passively until a trigger signal is selectively transmitted from the interrogation device  30  and received by the sensor assembly. Upon receipt of this signal, energy is collected and conditioned to temporarily power the sensor assembly  20 . Therefore, reading from the temperature responsive element  24 , which is proximity with the area of interest and is active throughout, is obtained. The reading is converted into an electrical signal which is then wirelessly transmitted to the interrogator device  30 . 
         [0057]    As shown in  FIG. 9 , it should be readily apparent that more than one sensor assembly can be placed or positioned for use on a subject. There are instances when a plurality of sensor assemblies  144  can be attached to the arm  148  or other area of a subject, for example, to determine if there is a broken bone, a blood clot, or other injury when thermal variations can be determined to locate same. 
         [0058]    Though the preceding has been shown with a single form of miniature parameter (e.g., a temperature) sensor, it should be readily apparent that at least one other form of physiological parameter sensor, such as, but not limited to heart rate, SPO2, and respiration can be attached to the sensor assembly. 
         [0059]    Several applications of the above disposable sensor assembly are possible. For example and referring to  FIG. 8 , one potentially useful application for the herein described sensor assembly is in connection with an inflatable blood pressure cuff or sleeve  150 . The sleeve  150  is wrappable about a limb of a subject and includes hook and loop fasteners  154  that permit an adjustable securement of the sleeve. A top facing side  162  of the sleeve  150  shown includes artery markers  158  that are used to align the sleeve with the brachial artery of the arm  184  of the subject, as well as a socket (not shown) permitting direct connection of a gage housing  168 . The sleeve  150  further includes a hose  172  attached to a pneumatic bulb (not shown) that is fluidly connected to the interior of the sleeve  150  through a coupling  176 . A sensor assembly  180 , such as those previously described above and shown in phantom, is attached to the bottom facing side of the sleeve (that is, the side facing the subject) wherein temperature readings can be selectively gathered in conjunction with blood pressure readings using the sensor assembly in the manner previously described using interrogation device  30 . Alternately and as further detailed below, the sensor assembly  180  can be attached to any portion of the sleeve  150  and used to detect the presence of the sleeve via transmission of an identification signal in response to the trigger signal transmitted by the interrogation or other suitable device. This function is described in greater detail below with reference to  FIG. 10 . 
         [0060]    This inventory and/or tracking method is more fully depicted according to  FIG. 10  in which several instruments or apparatus in a patient room can be located and identified by an interrogation device  30  upon a caregiver entering the room. In this embodiment, several pieces of equipment, such as a vital signs monitor  200 , an EKG or EEG monitor  204  and other types of equipment  208 , such as the afore mentioned blood pressure sleeve  150 ,  FIG. 9 , are tagged using the above sensor assemblies  212 , each sensor assembly preferably including a programmable memory that stores product information pertaining to the device that the sensor assembly is attached to. In essence, each of the sensor assemblies  212  are therefore used as tags wherein use of the interrogation device  30  and emission of the appropriate trigger signals identifies all equipment in a subject&#39;s room as displayed by the device. This method is useful in determining not only in locating or determining any equipment that is in the room, but also in expediting examination and physician rounds due to the potential time savings in not having to locate and otherwise retrieve equipment by means of the convenient tagging capability of the sensor assemblies  212 . 
         [0061]    The above method provides a means of traceability, for example, to determine whether or not a specific piece of equipment has been used in conjunction with a patient, settling, for example, potential billing and liability issues. Moreover, the physiological data obtained could be married with the equipment used. In a preferred version, the equipment (e.g. a vital signs monitor such as those manufactured under the tradename of Propaq® by Welch Allyn, Inc.) can wirelessly transmit physiological data directly to the sensor assembly for storage in the memory of the ASIC. This data can then subsequently be uploaded to the interrogation device when the trigger is transmitted to the sensor assembly. 
         [0062]    Turning to  FIG. 11 , the sensor assembly can be used not only for external subject diagnosis, but also for determining a number of other patient-related conditions when used in connection with an endoscope or similar device (the insertion tube  220  being shown in the Fig.) that can be implanted within a subject&#39;s body cavity  224  (shown only schematically in  FIG. 11 ), wherein a sensor assembly  228  can be attached to the exterior of the tube  220 . Alternately, the insertion tube  220  can be used to actually implant a sensor assembly within the body cavity for a particular treatment and the assembly can then be subsequently removed at the end of the treatment. 
       PARTS LIST FOR FIGS.  1 - 11   
       [0000]    
       
           10  apparatus 
           20  sensor assembly 
           24  temperature responsive element 
           28  low power A/D circuit 
           30  interrogation device 
           32  emitter and receive circuitry 
           34  subject 
           35  unit serial number 
           36  antenna 
           38  emitter and receive circuitry 
           40  temperature computation algorithm(s) 
           42  serial interface 
           46  antenna 
           48  user interface 
           50  sensor assembly 
           54  first disposable supporting portion 
           58  second reusable portion 
           62  temperature responsive element 
           66  flexible strip 
           68  top surface 
           70  adhesive backing 
           74  leads 
           78  connection coupling leads 
           84  body portion 
           88  ASIC 
           92  wireless transmitter/receiver 
           96  antenna 
           100  sensor assembly 
           104  substrate 
           108  ASIC 
           112  thermistor 
           116  wireless transmitter 
           120  receiver 
           124  antenna 
           128  LCD 
           132  input controls 
           138  housing body 
           144  disposable sensor assemblies 
           148  arm 
           150  blood pressure sleeve 
           154  hook and loop fasteners 
           158  artery markers 
           162  facing side 
           168  gage housing 
           172  hose 
           176  coupling 
           180  sensor assembly 
           184  arm 
           200  vital signs monitor 
           204  EKG or EEG monitor 
           208  other equipment 
           212  sensor assemblies 
           220  insertion tube 
           224  body cavity 
           228  sensor assembly 
       
     
         [0118]    While the present invention has been particularly shown and described with reference to the preferred mode as illustrated in the drawings, it will be understood by one skilled in the art that various changes in detail may be effected therein without departing from the spirit and scope of the invention as defined by the following claims.