Patent Publication Number: US-2007096897-A1

Title: Attachment/location monitoring of a signal generating entity

Description:
CROSS-REFERENCE TO APPLICATIONS INCLUDING RELATED SUBJECT MATTER  
      This application includes subject matter related to co-pending and commonly owned U.S. non-provisional patent application Ser. No. 11/031,736 (Attorney docket: 704 — 047CON), filed Jan. 7, 2005), which is a continuation of non-provisional application Ser. No. 10/806,770 (Attorney docket: 704 — 047), filed Mar. 22, 2004 claiming priority to U.S. provisional patent application Ser. No. 60/456,609 (Attorney docket: 704 — 047PRO1), filed Mar. 21, 2003 and claims priority to U.S. provisional patent application Ser. No. 60/554,706 (Attorney docket: 704 — 047PRO), filed Mar. 20, 2004. This application also includes subject matter related to commonly owned and issued U.S. Pat. No. 6,616,606 titled “Patient Monitoring System”. The aforementioned patent and all of the aforementioned patent applications are herein incorporated by reference in their entirety. 
    
    
     FIELD OF THE INVENTION  
      This invention relates generally to reliably monitoring the status of an attachment between an attachment reporting device and a mobile entity, such as a person, another type of living thing or a device, in circumstances where the mobile entity generates a characteristic entity signal, such as an ECG or an EEG signal. In particular, the invention relates to reliably monitoring the status of an attachment between a mobile entity that generates a medical (physiologic) signal and a location reporting device, in order to reliably track the location of the mobile entity over a period of time.  
     BACKGROUND OF THE INVENTION  
      Various status reporting devices, such as physiological status or location status reporting devices, are configured to report (communicate) status information associated with a person or an object to a remote location. Typically, a status reporting device is attached to a person or an object, Such as a piece of portable equipment. Often, the reliability of status information communicated from the status reporting device substantially depends upon the person or object to which the device is attached. For example, status reporting devices are substantially more reliable when attached to individuals other than those individuals who cannot be trusted to cooperate with the reporting of their status.  
     SUMMARY OF THE INVENTION  
      The invention provides a method and apparatus for reliably monitoring the status of a physical attachment between an attachment monitoring device and a mobile entity, such as a person, another type of living thing, such as an animal or a device, in circumstances where the mobile entity generates a characteristic entity signal. The characteristic entity signal can be for example, an electrocardiogram (ECG) signal or an encephalogram (EEG) signal generated from a target, such as a person or other living thing. The presence of a physical attachment between an attachment monitoring device and a mobile entity is verified via continuous detection of the entity signal by the attachment monitoring device.  
      Optionally, the attachment monitoring device can transmit a signal that reports the status of the physical attachment and can also function as, or be attached to, or be located within a range of proximity to, another type of monitoring/reporting device, such as for example, a location reporting device.  
      In one type of embodiment, an attachment monitoring device is attached to a mobile entity and simultaneously attached to a location reporting device. The attachment monitoring device reports upon the status of an attachment between itself and the mobile entity while the location reporting device reports upon the location of the mobile entity, to a remote entity over a period of time. Severance of the attachment between the attachment monitoring device and the mobile entity or of the attachment between the location reporting device and the attachment monitoring device is reported to the remote entity.  
      The combination of both an attachment monitoring device and a location reporting device together forms a location monitoring apparatus that communicates more reliable location status information to the remote entity. Further, different types of physiological status monitoring devices can be used to implement an attachment monitoring device while different types of location monitoring devices, or non-location monitoring devices can be selectively intermixed into attached device combinations that can be reliably attached to and report upon the status of a mobile entity (target).  
      According to some variations, the attachment monitoring device and the location reporting device are combined (embedded) into a single device. Optionally, the reporting signals for the two devices can be combined into a single signal.  
      The foregoing as well as other objects, aspects, features, and advantages of the invention will become more apparent from the following description and from the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The objects and features of the invention can be better understood with reference to the claims and drawings described below. The drawings are not necessarily to scale, the emphasis is instead generally being placed upon illustrating the principles of the invention. Within the drawings, like reference numbers are used to indicate like parts throughout the various views. Differences between like parts may cause those parts to be indicated by different reference numbers. Unlike parts are indicated by different reference numbers.  
       FIG. 1A  illustrates an attachment monitoring device implemented as an ECG signal monitoring device that is configured to be attached to a person;  
       FIG. 1B  illustrates an attachment monitoring device of  FIG. 1A  that is attached to a person;  
       FIG. 1C  illustrates an attachment monitoring system that includes a plurality of attachment monitoring devices of  FIG. 1A ;  
       FIG. 2A  illustrates a location monitoring device that is attached to a cart;  
       FIG. 2B  illustrates a location monitoring system that includes at least one location monitoring device of  FIG. 2A ;  
       FIGS. 3A-3B  illustrate an embodiment of an enhanced location monitoring apparatus that is formed from attaching a location monitoring device to an attachment monitoring device;  
       FIG. 3C  illustrates a combined monitoring system  350  including at least one combined attachment and location monitoring device  312   a - 312   n  of  FIG. 3B ; and  
       FIG. 4  is a table illustrating a qualitative estimate of the relative reliability of attachment status information provided by the enhanced location monitoring apparatus of  FIGS. 3A and 3B . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       FIGS. 1A and 1B  illustrate an embodiment of the invention in which an attachment monitoring  112  device is implemented herein as an electro-cardiogram (ECG) signal monitoring device  112 . It will be understood that the attachment monitoring device can be used in connection with other apparatus and that this embodiment is exemplary. In this embodiment, the ECG signal monitoring device  112  includes an ECG monitoring control unit  20  that is configured to be electrically connected to a lead-wire assembly  12  comprising a cable  14  having a connector port  17  which extends to a harness  15  having a plurality of ECG lead wires  10   a - 10   c  that are each electrically connected to corresponding ECG contacts  11   a - 11   c  respectively. The ECG monitoring control unit  20  includes an embedded ECG signal receiving component and an embedded reporting signal transmitting component. Two alternate control units  22  and  24  are depicted, for connection to the lead wire assembly  12 , as described in greater detail below.  
      In the embodiment shown, the ECG contacts  11   a - 11   c  make physical contact with the surface of the skin of a target  110  and form electrodes that receive an ECG signal  108  that is generated from the circulatory system (not shown) of the target  110 .  
      In this circumstance, the target  110  is a person  110  who could be a patient  110  located within a health care facility and/or someone who is confined to a restricted area. In other circumstances, the target  110  could be a living thing, such as, for example, a farm or ranch animal.  
      Preferably, the attachment monitoring device  112 , also referred hereto as a personal status monitoring device, includes the control unit  20  which can include a transport or a bedside monitor, for example. The transport monitor retains a set of batteries, enabling the device to be used as a transport apparatus. The device being battery powered consumes low power, preferably ultra low power in order to maximize its battery life. Batteries are stored within the control unit  20 .  
      As shown, the attachment monitoring device  112  includes a plurality of (3) electrical contacts  11   a - 11   c  that are configured to make physical contact with and optionally attach to the target  110 . The electrical contacts  11   a - 11   c  are configured to make physical contact with the target  110  for extended periods of time without causing harm or discomfort to the target  110 . The number of lead wires and corresponding contacts can be varied depending, for example, whether a 3-lead, 5-lead or other form of ECG configuration is required and this described configuration is again also meant to be exemplary.  
      Typically, each electrical contact  11   a - 11   c  includes conductive material that is configured to receive the ECG signal  108  from the target  110  and to relay the ECG signal  108  to the ECG signal receiving component located within the control unit  20  of the ECG signal monitoring device  112 . The ECG signal receiving component of the control unit  20  processes the analog ECG signal digitally and transmits (relays) a communication that at least represents the received ECG signal  108  ( FIG. 1B ) to the reporting signal transmitting component of the control unit  20 .  
      The control unit  20  is preferably a wireless and battery powered device that is portable and person-worn, meaning that it can be attached to the body of the target  110  (such as to the body of a patient) or attached to material, such as the clothing, that is attached to the body of the target  110 . For example, the control unit  20  can be disposed onto a sleeve or a belt attached to the body of the target (patient)  110 .  
      According to one version, the ECG monitoring device  112  is a Micropaq wireless patient-worn monitoring device  22  supplied by Welch Allyn Inc. of (Beaverton, Oreg.). The Micropaq patient-worn device  22  is a patient-wearable device that provides a variety of patient vital signs monitoring functionality. This functionality includes wirelessly transmitting ECG signals that are received from a patient as well as monitoring of other patient physiologic variables, such as heat rate, body temperature and pulse oximetry. As described earlier, the patient-wom device  22  embeds an ECG signal receiving component and a reporting signal transmitting component within its housing.  
      The reporting signal transmitting component receives the ECG signal  108  and relays another signal communication, directly or indirectly, to a remote entity such as a display or a central monitoring station, also referred to as a central station. In one embodiment, the central monitoring station is an Acuity central monitoring station manufactured by Welch Allyn, Inc. In one type of embodiment, the reporting signal transmitting component transmits, near simultaneously (in real time), a first reporting signal (not shown) to one or more remote first reporting signal receivers (See  FIG. 1C ).  
      The ECG monitoning control unit  20  is configured to relay events, signals, and information preferably bi-directionally, between the control unit  20  and a remote entity, for example, a monitoring station (See  FIG. 1C ). Preferably, the control unit  20  transmits a wireless reporting signal (See  FIG. 2 ) directly or indirectly to the monitoring station. Preferably, the ECG monitoring control unit  20  can use the bidirectional communication to detect the loss of communication between itself and the remote entity, and can generate a local audible alert indicating this loss of communication.  
      Optionally, one or more wireless receivers are employed to relay the wireless reporting signal ultimately to the monitoring station (See  FIG. 2 ). The reporting signal communicates information representing at least the status of the reception of the ECG signal  108  by the ECG monitoring control unit while functioning as an attachment monitoring device  112 .  
      The characteristics of the first reporting signal are not required to be equivalent to that of the ECG signal  108 , and in some embodiments, may be entirely different than the characteristics of the ECG signal  108 . In some embodiments, characteristics of the first reporting signal substantially resemble characteristics of the ECG signal  108 .  
      Preferably, the first reporting signal re-communicates at least some and possibly all of the information carried by the ECG signal  108 . At a particular point in time, the communication of the first reporting signal indicates the near simultaneous reception of an ECG signal by the ECG signal monitoring device  112  and indicates concurrent attachment of the ECG signal monitoring device  112  to the person  110 .  
      Alternately and as also shown in  FIG. 1A , the control unit  20  is a bedside Propaq CS wireless patient monitor  24  that is also manufactured by Welch Allyn, Inc. The depicted monitoring device is a portable device that provides a variety of patient vital signs monitoring functionality. This functionality includes wirelessly transmitting ECG signals, among other physiological parameter data that are received from a target (patient). The monitor  24  according to this embodiment, is typically attached to a portable chair or bed near the monitored target (patient), thereby functioning as a bedside monitor. As described earlier, the monitor  24  embeds an ECG signal receiving component and a reporting signal transmitting component within a housing.  
      In other embodiments, the ECG signal receiving component and the signal transmitting component are packaged separately and communicate via a wire line or wireless communications channel. The ECG signal receiving component can be implemented, for example, as a adhesive patch that is directly attached to the skin of the target (patient). In some embodiments, the wireless communications channel is provided by a wireless personal area network (PAN), such as for example, in accordance with the Bluetooth or ZigBee types of personal area networks.  
       FIG. 1C  illustrates an attachment monitoring system  150  that includes at least one attachment monitoring device  112  of  FIGS. 1A-1B . The system  150  includes at least one and preferably a plurality of attachment monitoring devices  112   a - 112   n,  implemented herein as ECG signal monitoring devices  112   a - 112   n,  as shown in  FIGS. 1A-1B . Each ECG signal monitoring device  112   a - 112   n  is assigned to and configured to receive an ECG signal  108  from a particular associated target (patient)  110  of among a plurality of targets (patients)  110   a - 110   n.    
      As shown in  FIG. 1B , each ECG signal monitoring device  112   a - 112   n  is configured to each transmit a first reporting signal  114   a - 114   n , respectively associated with each target  110   a - 110   n,  either directly or indirectly to a remote entity, such as a (attachment) monitoring station  120 . In some embodiments, a plurality of attachment monitoring stations  120  are each employed at one of a plurality of assigned locations. Each attachment monitoring station  120  is configured to monitor first reporting signals received at each of the one of the plurality of assigned locations. One attachment monitoring station can be assigned to function as a primary monitoring station, also referred to as a primary central station, to perform central monitoring of signals collectively received from the plurality of attachment monitoring stations.  
      Optionally and as shown, a plurality of intermediate first reporting signal receivers  116   a - 116   m  receive and relay the first signals  114   a - 114   n  to the monitoring station  120 . Note that the invention does not require a particular relationship between the number of ECG signal monitoring devices  112   a - 112   n  and the number of first reporting signal receivers  116   a - 116   m,  if any are employed in a particular embodiment.  
      According to this embodiment, each first reporting signal  114   a - 114   n  is preferably a wireless type of signal. As shown, the first reporting signal  114   a - 114   n  is received by at least one first reporting signal receiver  116   a - 116   m . Preferably, each of the first reporting signals  114   a - 114   n  is transmitted by each device  112   a - 112   n  in a manner that is nearly simultaneous with respect to the time each respective ECG signal  108   a - 108   n  is received by each device  112   a - 112   n  from each target  110   a - 110   n.    
      As shown in this embodiment, each of the first reporting signal receivers  116   a - 116   m  communicate (e.g., relay) information received from the first reporting signals  114   a - 114   n  to a monitoring station  120  via a plurality of communication channels  118   a - 118   m . In one type of embodiment the communications channels  118   a - 118   m  are each a wire-line type of communication channel that is implemented for example, via a local area network such as an Ethernet, or wide area network (WAN). In another type of embodiment, the communications channels  118   a - 118   m  are configured as a wireless type of communication channel, such as those including an 802.11 compliant channel.  
      Each of the communications channels  118   a - 118   m  are not required to be of a particular type or of the same type. Preferably, the relayed information is transmitted, nearly simultaneously, with respect to the time of reception of each respective first reporting signal  114   a - 114   n  by the receivers  116   a - 116   n.    
      The monitoring station  120  outputs information communicated by each of the first reporting signals  114   a - 114   n  that are associated with each target  110   a - 110   n.  Typically, the first reporting signal  114   a - 114   n  communicates at least some or all information communicated by the ECG signals  108   a - 108   n  that are received by each of the ECG signal monitoring devices  112   a - 112   n.    
      Preferably, the monitoring station  120  such as, for example, an Acuity central monitoring station includes a visual display, such as a liquid crystal display (LCD) monitor, for example, to represent the information received from each ECG signal monitoring device  112   a - 112   n . In some embodiments, the first reporting signals  114   a - 114   n  carry substantial ECG status information associated with each target  110   a - 110   n  such that the monitoring station  120  indicates an ECG status for each target  110   a - 110   n,  as well as an attachment status for each target  110   a - 110   n.    
      The presence (transmission) of a first reporting signal  114   a - 114   n  at a particular time indicates the following: First, the presence of an ECG signal  108  being generated from an ECG signal generating entity  110   a - 110   n;  second, an attachment is indicated between an ECG signal monitoring device  112   a - 112   n  generating the first reporting signal  114   a - 114   n  and the ECG generating entity  110   a - 110   n;  and third, the operation of the ECG signal monitoring device  112   a - 112   n , is indicated at that particular time.  
      As a result, a first reporting signal  114   a - 114   n  communicates information representing both an ECG status of an ECG signal generating entity  110   a - 110   n  as well as an attachment status between an ECG signal monitoring device  112   a - 112   n  and the ECG signal generating entity  110   a - 110   n.  Hence, the ECG signal monitoring device  112   a - 112   n  functions as an attachment monitoring device to confirm the status of an attachment between the device  112   a - 112   n  and the target  110   a - 110   n.    
      The absence of a first reporting signal  114   a - 114   n  at a particular time indicates an absence of an ECG signal  114   a - 114   n  being generated from a target  100   a - 110   n  from an attached ECG signal monitoring device  112   a - 112   n,  indicates an absence of an attachment between an ECG signal monitoring device  112   a - 112   n  and a target  110   a - 110   n,  or an absence of the collect operation of the ECG signal monitoring device  112   a - 112   n , or some combination thereof.  
      In some embodiments, by itself, the first reporting signal  114   a - 114   n  does not necessarily provide information uniquely identifying the ECG signal generating entity (target)  110   a - 110   n.  In addition, the first reporting signal  114   a - 114   n  by itself, does not necessarily provide information classifying the ECG signal generating entity  110 . For example, the first reporting signal  114   a - 114   n  does not necessarily provide information as to whether the entity  110   a - 110   n , for example, is a male or female, a human being, an animal or other type of living thing capable of generating an ECG or similar type of signal.  
      In a typical use scenario, an ECG signal generating entity (target)  110  is classified and uniquely identified. For example, in one use scenario, the target is an Alzlheimer&#39;s patient who is located within a health care facility. The target is uniquely identified, for example, by a full legal name, a health care facility identification number and/or social security number and other demographic and/or medical information. Upon physically attaching an ECG signal monitoring device  112   a - 112   n  to the target  110   a - 110   n  at a first attachment time, a first reporting signal  114   a - 114   n  is generated by the ECG signal monitoring device  112   a - 112   n.    
      Preferably, the monitoring station  120  associates, for at least a period of time, the first reporting signal  114   a - 114   n  and information uniquely identifying the target  110   a - 110   n . The period of time starts when the generation of the first reporting signal  114   a - 114   n  is initiated as a result of attaching a particular ECG signal monitoring device  112   a - 112   n  to a particular target  110   a - 110   n , referred to herein as a first reporting signal initiation time event or a first reporting signal initiation (FSI) event, and ends when the continuity of the generation of the first reporting signal is interrupted or terminated, referred to herein as a first reporting signal termination time event or a first reporting signal termination (FST) event. An FST event occurs regardless of whether the first reporting signal is terminated definitely or indefinitely.  
      For definitional purposes with regard to the following description, the occurrence of an earliest first reporting signal termination (FST) event after a first reporting signal initiation (FSI) event is referred to herein as being a first reporting signal termination (FST) event. which corresponds to the first reporting signal initiation (FSI) event, or that is coupled to the first reporting signal initiation (FSI) event and vice versa. The period of time commencing at a first reporting signal initiation (FSI) event and ending at a corresponding first reporting signal tennination (FST) event, is referred to herein as a continuous first reporting signal period (CFSP).  
      An event in which a particular ECG signal monitoring device  112   a - 112   n  is attached to a particular target  110   a - 110   n  is herein referred to as an attachment event. An attachment event that causes a first reporting signal initiation event, is also referred to as corresponding to the first reporting signal initiation (FSI) event and as corresponding to the continuous first reporting signal period that includes the first reporting signal initiation (FSI) event, and vice versa.  
      Accordingly, each continuous first reporting signal period corresponds to an attachment event associated with the attachment of a particular ECG signal monitoring device  112   a - 112   n  to a particular target  110   a - 110   n.  Preferably, the particular target  110   a - 110   n  is uniquely identified and associated with a first reporting signal  112   a - 112   n . As previously noted, the target can be, for example, an Alzheimer&#39;s patient within a health care facility and/or some one who is incarcerated within a facility.  
      During a continuous first reporting signal period, the presence (transmission) of a first reporting signal  114   a - 114   n  indicates the presence of an ECG signal  108   a - 108   n  being generated from the selected target  110   a - 110   n , indicates the presence of the attachment (first attachment) between an ECG signal monitoring device  112   a - 112   n  and the target  110   a - 110   n , and indicates the presence of the operation of the ECG signal monitoring device  112   a - 112   n.    
      Implicitly, the presence of the first reporting signal  114   a - 114   n  during a continuous first reporting signal period indicates the continuous presence of the ECG signal  114   a - 114   n , the continuous presence of the attachment (first attachment) and the continuous presence of the operation of the device  112   a - 112   n , since the time of the FSI event corresponding to that continuous first reporting signal period.  
      Accordingly, the identity of a target  110   a - 110   n  corresponding to a first reporting signal within a continuous first reporting signal period can be reliably associated with the presence of the first reporting signal during the continuous first reporting signal period. The presence of a first reporting signal outside of a continuous first reporting signal period cannot be reliably associated with the identity of a target  110   a - 110   n , and causes the identity of the target  110   a - 110   n  to be disassociated with the first reporting signal  114   a - 114   n.    
       FIG. 2A  illustrates a location monitoring device  212  that is physically attached to a mobile piece of hardware, such as a cart  210 . The cart  210  is configured to be mobile via a wheeled structure and can therefore, for example, be selectively located throughout a large facility. The cart  210  can be utilized within many types of facilities that typically include a substantial amount of space, equipment and personnel. Such types of facilities can include, for example, a health care or manufacturing facility.  
      In some circumstances, personnel that require use of the cart  210  may not know, but may need to know the location of the cart  210  within the facility at a particular time. The location monitoring device  212  is configured to transmit a location reporting signal  214  that communicates information regarding the location of the cart  210  over a period of time. Other receiving devices receive the location signal and report the location of the device  212  to enable personnel of the facility to track the location of the cart  210  over a period of time.  
      A typical indoor location monitoring device  212 , such as that provided by the Radianse Corp. of Lawrence, Mass., is configured to be directly attached to various types of materials including those such as metal, plastic, wood or paper, for example, but is unsuitable for directly attaching to the living tissue of a living entity. Direct attachment of a typical location monitoring device to a living entity, such as to the skin of a person  110 , for example, can cause discomfort and/or possible hann to the living entity.  
      For example, a typical Radianse location monitoring device uses an adhesive surface that adheres to the above noted types of materials. Directly adhering an adhesive surface of a location monitoring device  212  to the skin of a person, such as that of an Alzheinier&#39;s patient, can cause discomfort and/or possible harm, especially over extended periods of time.  
      Further, the direct attachment of a location monitoring device  212 , such as via an adhesive strip, to a living target  110 , can result in the generation of invalid location monitoring information associated with the living target  10 . For example, directly adhering an adhesive surface of a location monitoring device  212  to the skin of an Alzheimer&#39;s patient, may cause the Alzheimer&#39;s patient  110  to eliminate the discomfort associated with the attachment of the adhesive surface by detaching the adhesive surface and the location monitoring device  212  itself, from his or her skin.  
      As a result, the location monitoring device  212  is separated from the target  110  and the location of the target  110  can no longer accurately be monitored by the location monitoring device  112 . Any further location monitoring information transmitted by the device  112  therefore unreliable.  
      In some embodiments, the location monitoring device  212  has a detachment indicating mechanism. The detachment indicating mechanism transmits an indication that the direct attachment (second attachment) of the location monitoring device  212  to a surface attached to a target  110  has been severed. Preferably, the detachment indicating mechanism is highly reliable so that it is difficult for someone to detach or detach and reattach the location monitoring device  212  without this detachment/reattachment being detected and reported.  
      Preferably, a detachment indicating mechanism of this type provides an indication of the severance of an attachment between the location monitoring device  212  and surface attached to a target  110 , upon visual inspection. Typically, a detachment indicating mechanism employs, for example, a tamper switch that has a high likelihood of activating upon severance of an attachment between the location monitoring device  212  and a surface for attachment of the location monitoring device  212 . In some embodiments, a strong adhesive or epoxy is used between a location monitoring device  212  and surface that is attached to a target.  
      In certain embodiments, a detachment indicating mechanism for the device  212  is not available or may not applicable. For example, in some embodiments, both the attachment monitoring device  112  and the location monitoring devices are integrated (permanently attached) into a single stricture such that a detachment indicating mechanism is not required for reliable reporting of the location of a target  110 .  
      In other embodiments, some form of a detachment indicating mechanism may exist, but this mechanism may only reliably detect certain detachment scenarios and may be defeated by untrustworthy individuals to whom the device is attached initially. For example, some embodiments of a detachment indicating mechanism may be defeated by individuals attempting to steal portable equipment. For example, an individual may be able to defeat the detachment indicating mechanism, and to detach the location monitoring device  212  from a surface of the portable equipment, without triggering the detachment indicating mechanism.  1000641  In another scenario, and related to certain individuals to whom such a device may be attached the location monitoring device  212  may be indirectly attached to an article of clothing of a living target  110   a - 110   n.  For example, the location monitoring device  212  can be directly attached to a badge that is clipped to the clothing of the Alzheimer&#39;s patient  110 . Alternatively, the location monitoring device  212  might be clipped or otherwise attached directly to the clothing. An Alzheimer&#39;s patient may inadvertently or unwittedly remove the attached device  212 , the attached badge or the clothing and the attached device  212  or badge without knowing that such an action interferes with the validity of the location monitoring device  212  attached to the badge, or be unaware of being location monitored altogether.  
      Because the location monitoring device  212  remains directly attached to a badge, a detachment indicating mechanism, if any, does not activate. However, unknown to personnel receiving location monitoring information from the location monitoring device  212 , any further location monitoring information transmitted by the device  212  cannot be relied upon.  
      In another scenario, the location monitoring device may be attached to hand cuffs or leg irons placed upon an incarcerated individual. In order to escape a facility, the hand cuffs and/or leg irons may be sawed through or otherwise removed, in such a manner to detach the hand cuffs and/or leg irons from the incarcerated individual without activating a detachment indicating mechanism, if any, and without deactivating the location reporting functionality of the location reporting device  212 . Unknown to personnel receiving location monitoring information from the location monitoring device  212 , any further location monitoring information transmitted by the device is therefore unreliable.  
      In these types of scenarios, personnel relying upon information provided by the location monitoring signal  114   a - 114   n  may be unaware that the location monitoring device  212  is no longer attached to the target  110  and that location monitoring information transmitted by the device  112  is unreliable. To address this problem, the invention provides a reliable indicator of an actual attachment (e.g., second attachment) between a location monitoring device  212  and a target  110 .  
      To that end,  FIG. 2B  illustrates a device location monitoring system  250  including at least one location monitoring device  212   a - 212   n  of  FIG. 1A . Each location monitoring device  212   a - 212   n  is configured to transmit a location reporting signal  214   a - 214   n , also referred to herein as a second reporting signal  214   a - 214   n . In this embodiment, each second (location) reporting signal  214   a - 214   n  is a wireless type of signal that is received by at least one receiver  216   a - 216   l . Each of the receivers  216   a - 216   l  communicate information received from the second (location) reporting signals  214   a - 214   n  to the location monitoring station  220  via communication channels  218   a - 218   l  respectively.  
      In some embodiments, the communications channels  218   a - 218   l  are wire line communication channels that travel through a local and/or a wide area network. In other embodiments, the communications channels  218   a - 218   l  are wireless communications channels, such as compliant with the 802.11 standard.  
      The monitoring station  220  outputs information communicated by the second (location) reporting signals  214   a - 214   n  transmitted by each of the location monitoring devices  212   a - 212   n . Preferably, the location monitoring station  220  includes a visual display, such as a liquid crystal display (LCD) monitor, for example, to represent the information received from each of the location monitoring devices  212   a - 212   n  via each of the second reporting signals  214   a - 214   n , respectively.  
      In some circumstances, a location device  212  can be detached from one target device, such as the cart  210 , and attached to another target device that is not intended to be monitored by facility personnel. For example, the location device  212  could be detached from the cart  210  and re-attached to a wheel chair, a stationary chair or a bed flame, or simply dropped onto the floor or otherwise disposed of by an individual or through loss of adhesion.  
      In some embodiments, a location monitoring device  212  may be configured to be tamper resistant in order to detect detachment from a target device  212 . In some embodiments, the location monitoring device  212  has a detachment reporting mechanism. In one type of embodiment, the detachment reporting mechanism transmits a communication, such as an electro-magnetic signal, indicating that the physical attachment (second attachment) between the location monitoring device  212  and a target  210  has been severed. In other embodiments, physical inspection of the location monitoring device  212  reveals that the device was previously detached from a target  212 , even if it is later re-attached to the target  212 . However, no communication reporting mechanism exists.  
      As stated earlier, in some embodiments, some form of a detachment indicating mechanism may exist, but it may only reliably detect the occurrence of certain detachment scenarios and may be defeated by the actions of the target  110   a - 110   n.  For example, a solvent may be used to counteract the adhesive properties of the adhesive, and detach the location monitoring device without triggering the detachment indicating mechanism.  
      In this latter circumstance, further information communicated from the location device  212  to the monitoring station  120  is unreliable. If no detachment indicating mechanism exists, or if a detachment indicating mechanism does not activate or is defeated, unknown to personnel receiving location monitoring information from the location monitoring device  212 , any further location monitoring information transmitted by the device  212  is unreliable.  
       FIGS. 3A and 3B  illustrates an embodiment of an enhanced location monitoring apparatus  312  that is formed from attaching a location monitoring device  212  to an attachment monitoring device  112 . As previously described, the attachment monitoring device  112  is implemented in this particular embodiment as an ECG signal monitoring device  112  that is attached to a target  110 .  
      According to this embodiment, the location monitoring device  212  is configurable to be attachable to a surface of another object. The rear surface  215  of the device  212  includes an adhesive surface. To attach the location monitoring device  212  to the first signal reporting component  20  (control unit), the rear side  215  of the device  212  is pressed and adhered to the rear surface  21  of the first reporting signal device (control unit)  20 .  
      Further, the location monitoring device  212  includes a detachment reporting mechanism  213  located on a rear surface  215  of the device  212 . The detachment reporting mechanism  213  is configured to cause the transmission of a communication to a second reporting signal receiver  216   a - 216   n  when an attachment between the location monitoring device  212  and any other object that (such as the first reporting signal device (control unit)  20 ) that the device  212  is attached to, is severed. The event of severing attachment (second attachment) is referred to as a detachment event.  
      In one embodiment, the attachment monitoring device  12  is a patient-worn patient monitoring device  22  such as a Micropaq monitoring device manufactured by Welch Allyn, Inc. and the first signal receivers  114   a - 114   m  and associated communications channels  118   a - 118   m  are implemented by a 802.11 wireless spread spectrum network such as the FlexNet wireless network utilized by Welch Allyn, Inc. Alternate implementations maybe in accordance with 802.11 a, b or g. Also, within the preferred embodiment, the location monitoring device  212  is implemented as a Radianse active RFID tag and the receivers  216   a - 216   l  are implemented as Radianse active RFID tag receivers. Both the active RFID tag and the active RFID tag receivers  216   a - 216   l  are supplied by Radianse Inc. of Lawrence, Mass.  
      This particular type of location monitoring device  212  employs a combination of both RF and infrared technology to accurately determine the indoor location of the location monitoring device  212  within a large indoor facility. This device  212  also includes a detachment reporting mechanism. The detachment reporting mechanism transmits a communication to a second reporting signal receiver  216   a - 216   l  if an attachment from an object, such as an attachment (second attachment) to the attachment monitoring device  112 , is severed.  
      In this embodiment, a first reporting signal  114  provides both the ECG status of the target  110  and the attachment status (first attachment) of the attachment monitoring device  112  to the target  110 . In the absence of a transmission of a detachment event communication from the location monitoring device  212 , the presence of a first reporting signal  114  also indicates the attachment (second attachment) of a location monitoring device  212  to the attachment monitoring device  112 . The presence of a second reporting signal  214  provides the location status of the location monitoring device  212 , the location status of the target  110  and the location status of the attachment monitoring device  112  as it is physically attached to the target  110 .  
      Physically attaching both types of devices  112 ,  212  together forms a combined and enhanced location monitoring apparatus  312  that communicates more reliable target location status information to the personnel of a facility. Further, different types of ECG and or other physiological monitoring devices and/or different types of location and/or other types of monitoring devices can be mixed and matched into attached device combinations that can be reliably attached to a target  110  via the attachment monitoring portion of the device combination.  
      In some embodiments, a (location) monitoring station  220  is configured to provide a user interface via the visual display that enables personnel to define a set of boundaries that identify a perimeter of a confining area. The targets  110   a - 110   n  are desired and/or expected and/or required to be located within the confining area. The location monitoring station  220  is also configured to detect a boundary violation event where one or more targets  110   a - 110   n  are detected to be located on a side of a boundary within tile set of boundaries that is located outside of the confining area.  
      Further, the location monitoring station  220  is also configured to notify personnel of one or more boundary violation events. In one type of embodiment, the location monitoring station  220  causes the generation of an audible notification and/or a visual notification and/or a signal notification upon the occurrence of boundary violation event and/or upon the occurrence of a detachment of an attachment monitoring device  112  from a target  110   a - 110   n  (signal generating entity) and/or upon the occurrence of a detachment of said location reporting device  212  from said attachment monitoring device  112 .  
      The audible notification can be implemented as a continuous or intermittent sound, such as a beeping or chirping sound. The visual notification can be implemented as a continuous or flashing light. The signal notification can be implemented as a communication to one or more communications devices wom or carried by, or located proximate to, personnel of a facility associated with the location monitoring station. In some embodiments, the communications devices are one or more pagers and/or cellular telephones that are each worn by personnel of the facility.  
      In some circumstances, a target  110   a - 110   n  may travel out of range of the receivers  116   a - 116   n . This type of circumstance is referred to as a dropout event. The monitoring station  120  is configured to detect and report a dropout event to personnel via audio and/or visual and/or signal alamis as described in response to a detachment event. The current or last reported location of the target  110   a - 110   n  can be used by facility personnel to locate and verify the status of the target  110   a - 110   n  associated with the dropout event.  
      If a detachment event occurs during a dropout event, the attachment monitoring device  112  is configured to alarm with an audio notification and a signal notification. The signal notification signal continues so that the central monitoring station  120  can receive it when the target travels within range of the one or more receivers  116   a - 116   m . For example, a target  110   a - 110   n  can travel out of range when entering an elevator and can travel within range when exiting the elevator. If a detachment event does not occur before, during and after the target enters and exits the elevator, the target  110   a - 110   n  will re-establish an association with a monitoring station  120 ,  220  and continue to be monitored after leaving the elevator, as if the target  110   a - 110   n  did not previously travel out of range. This is an example of what is herein referred to as Rendezvous functionality as is described in greater detail according to U.S. Pat. No. 6,616,606, previously incorporated by reference herein. The Rendezvous functionality is typically incorporated into systems that also incorporate the Micropaq and Propaq CS monitoring devices.  
       FIG. 3C  illustrates a combined monitoring system  350  including at least one combined attachment and location monitoring device  312   a - 312   n  of  FIG. 3B . In one embodiment, each combined attachment and location monitoring device  312   a - 312   n  is configured to transmit a combined signal  314   a - 314   n . The combined signal  314   a - 314   n  represents information communicated by the first reporting signal  114   a - 114   n  and second reporting signal  214   a - 214   n.    
      In some embodiments, the combined signal is a plurality (grouping) of signals, that includes a separate first (attachment) reporting signal  114   a - 114   n  and a second (location) reporting signal  214   a - 214   n . In other embodiments, the combined signal  314   a - 314   n  is one signal that combines information communicated by both the first (attachment) reporting signal  114   a - 114   n  and the second (location) reporting signal  214   a - 214   n . As shown in this embodiment, each combined reporting signal  314   a - 314   n  is a wireless type of signal that is received by at least one receiver  316   a - 316   l.    
      Each of the receivers  316   a - 316   l  communicate information received from the combined reporting signal  314   a - 314   n  to the combined monitoring station  320  via communication channels  318   a - 318   l  respectively. In some embodiments, the communications channels  318   a - 318   l  are wire line communication channels that travel through a local and/or a wide area network. In other embodiments, the communications channels  318   a - 318   l  are wireless communications channels, such as compliant with the 802.11 standard.  
      The combined monitoring station  320  inputs, processes and outputs information communicated by the combined reporting signal  314   a - 314   n . The combined monitoring station  320  combines and integrates the functionality of the attachment monitoring station  120  and the location monitoring station  220  to monitor and associate both the attachment and location status of one or more targets  110   a - 110   n.    
      The combined monitoring station  320  monitors, associates and indicates a first reporting signal initiation (FSI) event and first reporting signal termination (FST) event to define a continuous first reporting signal (CFSP) period over time in association with each target  110   a - 110   n.  The monitoring station  320  further associates the CFSP period and the FSI and FST events and with the location status of each target  110   a - 110   n  to provide a reliable and integrated attachment and location status of targets  110   a - 110   n  to facility personnel.  
      In other embodiments, non-location status reporting functionality, such as other physiological status or other types of target status for example, can combine with or replace the location status functionality. In other embodiments, other attachment monitoring functionality, such as functionality monitoring EEG signals, and combine with location status and/or non-location status functionality.  
      Like the monitoring stations  120  and  220 , the combined monitoring station  320  includes a visual display, such as a liquid crystal display (LCD) monitor, for example, to represent the information received from each of the combined location monitoring devices  312   a - 312   n  via each of the combined reporting signals  314   a - 314   n , respectively.  
       FIG. 4  is a table illustrating a qualitative estimate of the relative reliability of status information provided by the enhanced location monitoring apparatus  312  of  FIG. 3B . Table entry  372  represents a “true positive” operating circumstance. A true positive operating circumstance as defined herein is the circumstance in which the apparatus  312  communicates a positive indication of the presence of an attachment (first attachment) between the apparatus  312  and a target  110  wherein this indication is valid, as opposed to being invalid. As indicated by table entry  372 , given the circumstance where the apparatus  312  indicates anl attachment (first attachment) between the apparatus  312  and a target  110  (indicated circumstance), there is a high likelihood that the attachment (first attachment) actually (really) exists at that time (actual circumstance).  
      A “high likelihood” is assigned to this circumstance because, at this time, no suitably practical technique has been identified to detach the attachment monitoring device  112 ,  312  from a target  110  without interrupting (terminating) the first reporting signal  114   a - 114   n  for a small period of time. Preferably, the monitoring station  120  detects an absence of the first reporting signal  114   a - 114   n  for a time period as small as 1/60 of a second.  
      In this type of embodiment, even if the contacts  11   a - 11   b  were transferred and then re-attached to an ECG signal generating body of another target momentarily by the fastest means known to provide such detachment/reattachment, the resulting first reporting signal  114   a - 114   n  would be interrupted for a period of time exceeding 1/60 of a second. As a result the system  150 , via the monitoring station  120 , would detect the detachment of the contacts  11   a - 11   b,  despite any “fast” transfer and re-attachment of the contacts  11   a - 11   b  to another ECG signal generating entity, and indicate to personnel that the attachment monitoring device  112 ,  312  has been detached from the target  110 . Accordingly, the apparatus  312  provides a positive indication of an attachment (first attachment) between the apparatus  312  and another entity, with high reliability.  
      Table entry  374  represents a “false positive” operating circumstance. A false positive operating circumstance for purposes of this description is the circumstance in which the apparatus  312  communicates a positive indication of the presence of an attachment (first attachment) between the apparatus  312  and a target  110 , and in which this indication is in reality false. As indicated by table entry  374 , given the circumstance in which the apparatus  312  indicates anl attachment (first attachment) between the apparatus  312  and a target  110  (indicated circumstance), there is an insignificantly small likelihood that no attachment (first attachment) actually exists (actual circumstance). As in the preceding, the apparatus  312  provides a positive indication of an attachment (first attachment) with high reliability.  
      It is a challenge to construct a plausible scenario in which a false positive operating circumstance can occur. One scenario is that the monitoring station  120 , due to a defect, fails to detect a discontinuity of the transmission of a first reporting signal  114  that is a result of a detachment of the apparatus  112 ,  312  from the known target  110  and a re-attachment of the apparatus  112 ,  312  to another unknown target. The apparatus  112 ,  312  generates what appears to be, from the perspective of the monitoring station  120 , a continuous and uninterrupted first reporting signal  114 , despite the apparatus having been detached from the known target  110 . In this circumstance, personnel are unaware of the detachment of the apparatus from the known target  110  and are misinformed regarding the location of the known target  110 .  
      Table entry  378  represents a “tnie negative” operating circumstance. A true negative operating circumstance according to this description is the circumstance in which the apparatus  112 ,  312  communicates a negative indication of the presence of an attachment (first attachment) between the apparatus  312  and a target  110 , and in which this indication is valid, meaning no attachment (first attachment) actually exists. As indicated by table entry  376 , given the circumstance in which the apparatus  312  indicates no attachment (first attachment) between the apparatus  312  and a target  110  (indicated circumstance), there is a likelihood that there actually is no attachment (first attachment).  
      Table entry  376  represents a “false negative” operating circumstance. A false negative operating circumstance according to this description is the circumstance in which the apparatus  112 ,  312  communicates a negative indication of the presence of an attachment (first attachment) between the apparatus  312  and a target  110 , and in which this indication is invalid, meaning an attachment (first attachment) does actually exist. As indicated by table entry  376 , given the circumstance in which the apparatus  312  indicates no attachment (first attachment) between the apparatus  312  and a target  110  (indicated circumstance), there is a small likelihood that there actually is an attachment (first attachment).  
      A false negative operating circumstance can occur as a result of a device failure, in which the apparatus  112 , 312  fails to generate a first reporting signal even though the device is actually attached to ECG signal generating entity. This circumstance could be caused, for example, by battery exhaustion, a manufacturing defect or damage caused to the apparatus  112 ,  312 , accidentally or intentionally by the target  110 .  
      A benefit of the invention is that when the apparatus  112 ,  312  indicates the presence of an attachment (first attachment) between the apparatus  112 ,  312  and a target  110 . there is a high likelihood that an attachment (first attachment) actually exists between the apparatus  312  and the target. As a result, the apparatus of the invention  112 ,  312  is particularly suitable and useful for situations in which personnel need to know with high reliability that a particular device is attached to, or located within proximity of, a particular target.  
      Use of other types of physical attachments to a target  110  may be less reliable, especially if the target  110  is motivated to sever the attachment and/or if there is not a continuous communication to personnel in a timely fashion of the status of the attachment to the target  110 .  
      A discontinuity within the transmission of the first reporting signal  114 , referred to as a termination or a termination event of a first reporting signal  114 , indicates a significant likelihood of a detachment (severance of a first attachment) between the attachment monitoring device  112 ,  312  and its associated target  110 , and indicates detachment (disassociation) between the location monitoring device  212  and the target  110 . Also, the transmission of a detachment event communication from the location monitoring device  212  indicates a detachment (severance of the second attachment) between the location monitoring device  212  and the attachment monitoring device  112  and a detachment (disassociation) between the location monitoring device  212  and its target  110 .  
      In the above described circumstances, in which the first and/or the second attachments are severed, personnel relying upon information provided by the location monitoring device  212  will be aware that the location monitoring device  212  is no longer attached to the target  110  and that location monitoring information transmitted by the device  212  cannot be relied upon as being associated with the target.  
      In other circumstances, the ECG signal monitoring device component  112  of the apparatus  312  may have ceased operating or the target (patient) has ceased generating an ECG signal  108 . In either circumstance, the location status information continuing to be provided by the second reporting signal  214   a - 214   n  can quickly lead personnel to the target  110  in order to evaluate the type of circumstance causing the termination of the first reporting signal  114  and to take appropriate action.  
      Another benefit of the invention is that in the unlikely event that the attachment monitoring device  112  transmits a false negative indication, the cost of such an event (occurrence) is small. For example, upon the occurrence of such an event, one of the personnel (attendant) of the facility can walk to the currently reported or last reported location of the target  110  to verify the status of the target  110  and to correct any apparent problem with the device  112 . The event may be caused by a low battery or loose cable which can be corrected by an attendant. Upon fixing an apparent problem, the status of the target can be reset at the monitoring station and/or the attachment monitoring device  112  can be replaced with a more reliable copy of the device  112 .  
      In accordance with the invention, the location monitoring device  312  provides location information for persons and living things with particular reliability. Any detachment of the attachment device  112 ,  312  from the body of a living target  110  is reliably indicated by the termination of a first reporting signal  114   a - 114   n.    
      In another type of embodiment, the attachment monitoring device  112  and the location monitoring device  212  can be integrated into one combined attachment/location monitoring device that transmits both a first  114   a - 114   n  and a second  214   a - 214   n  signal. In a variation of this type of embodiment, the combined attachment/location monitoring device transmits a combined signal that communicates information indicating both the attachment status and location status of the attachment/location monitoring device. The attachment status and the location status can each be represented by separate characteristics of the combined signal.  
      For this type of embodiment, when a signal characteristic representing the attachment status indicates the occurrence of a detachment event, the location characteristic of the signal, at the time of the detachment event, indicates where the detachment of the combined monitoring device from the target  110 , had occurred so that personnel can take appropriate action.  
      In other embodiments, the attachment monitoring device  112  can be attached to other types of location monitoring devices. In one type of embodiment, the attachment monitoring device  112  is attached to an outdoor location monitoring device such that the location and/or physiological (e.g., ECG) status of a target  110  can be monitored while the target  110  is located outdoors for example, while driving on a highway, while in a large crowd at a sporting event, or on a golf course, or in a park etc.  
      In one type of outdoor location monitoring embodiment, the outdoor location monitoring device  112  employs global positioning system (GPS) technology. GPS technology employs a plurality of GPS satellites that receive a radio frequency signal transmitted from a GPS location monitoring device  212 . The GPS satellites are configured to accurately identify the location of a target transmitting an RF signal. The employment of GPS technology within a location monitoring device  212  enables the location of an attached target  110  to be tracked over a wide areas on the surface of the earth, provided that a direct path of signal transmission between the target  110  and any participating GPS satellite is not obstructed as a result of the target being located inside of a structure, below an outdoor roof or otherwise impeded.  
      In one type of outdoor location monitoring embodiment, location monitoring device employs “enhanced 911 ” location technology. This technology is currently under development and is required to locate mobile telephones during a possible emergency, such as in response to the dialing of ‘911’ from a mobile telephone. Currently, “enhanced 911” technology is expected to be derived from GPS and/or mobile telephone signal triangulation related technologies. Other technologies may be employed.  
      In other types outdoor location monitoring embodiments, the location monitoring device  212  employs other types of radio frequency (RF) technology. In some RF technology embodiments, 802.11 wireless access points and networking are employed to support the operation of a location monitoring device  212  outdoors. These types of location monitoring solutions include those, for example, supplied by business entities such as Aruba Networks of Sunnyvale, Calif., Airespace of San Jose, Calif. and Ekahau of Saratoga, Calif.  
      Radio frequency technology can be employed, by itself, to support indoor location monitoring. However, the accuracy of RF technology by itself, is typically less than the combination of RF technology and other technologies. For example, particular embodiments of RF technology in combination with infrared signal technology has yielded more accurate indoor location monitoring systems than RF technology alone, as claimed in association with indoor location monitoring products provided by Radianse Inc.  
      With respect to outdoor location embodiments, RF technology over a large area will typically not yield results as accurate as GPS technology. In other outdoor embodiments, the outdoor location monitoring device  112  can employ infrared or ultrasonic technology. However, the range of this technology is generally much shorter than that of GPS or other types of radio frequency technology.  
      In other types of embodiments, the attachment monitoring device  112  can be attached to one or more devices that are other than or not necessarily location monitoring devices  212 . For example, if an Alzheimer&#39;s patient  110  must wear an oxygen mask or an insulin injection device, the attachment monitoring device  112  can be configured to indicate that the air mask and/or insulin injection device are in fact, being worn by the Alzheimer&#39;s patient  110 . Also, in other embodiments, the attachment monitoring device  112  can be attached to devices monitoring other physiological characteristics of a target  110 , including devices monitoring brain waves (EEG), body temperature or pulse rate, for example.  
      As previously noted, the physiological signals can be generated and monitored by the target (patient) vis a vis the attachment monitoring device  112 , including brain wave activity, for example. In yet other types of embodiments, the attachment monitoring device  112  can be configured to attach to other living things that also generate an ECG signal, including domestic, family and zoo animals, including birds.  
      While the present invention has been explained with reference to the structure disclosed herein, it is not confined to the details set forth and this invention is intended to cover any modifications and changes as may come within the scope and spirit of the following claims.