Patent Publication Number: US-2012029300-A1

Title: System and method for reducing false alarms and false negatives based on motion and position sensing

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     The following applications disclose certain common subject matter with the present application: A Vital-Signs Monitor with Encapsulation Arrangement, docket number 080624-0612; A Vital-Signs Monitor with Spaced Electrodes, docket number 080624-0623; A Vital-Signs Patch Having a Strain Relief, docket number 080624-0624; A Temperature Probe Suitable for Axillary Reading, docket number 080624-0625; A System and Method for Detecting Loss of Thermal Contact Between a Patient and a Temperature Probe, docket number 080624-0626; A System and Method for Storing and Forwarding Data from a Vital-Signs Monitor, docket number 080624-0627; A System and Method for Conserving Battery Power in a Patient Monitoring System, docket number 080624-0629; A System and Method for Saving Battery Power in a Patient Monitoring System, docket number 080624-0630; A System And Method for Tracking Vital-Signs Monitor Patches, Docket Number 080624-0631; A System And Method for Reducing False Alarms Associated with Vital-Signs Monitoring, Docket Number 080624-0632; A System And Method for Location Tracking of Patients in a Vital-Signs Monitoring System, Docket Number 080624-0633; all of the listed applications filed on ______. 
     FIELD 
     The present disclosure generally relates to systems and methods of physiological monitoring, and, in particular, relates to systems and methods for reducing false alarms based on motion and position sensing. 
     DESCRIPTION OF THE RELATED ART 
     Some of the most basic indicators of a person&#39;s health are those physiological measurements that reflect basic body functions and are commonly referred to as a person&#39;s “vital signs.” The four measurements commonly considered to be vital signs are body temperature, pulse rate, blood pressure, and respiratory rate. Most or all of these measurements are performed routinely upon a patient when they arrive at a healthcare facility, whether it is a routine visit to their doctor or arrival at an Emergency Room (ER). 
     Vital signs are frequently taken by a nurse using basic tools including a thermometer to measure body temperature, a sphygmomanometer to measure blood pressure, and a watch to count the number of breaths or the number of heart beats in a defined period of time, typically 10 seconds, which is then converted to a “per minute” rate. If a patient&#39;s pulse is weak, it may not be possible to detect a pulse by hand and the nurse may use a stethoscope to amplify the sound of the patient&#39;s heart beat so that she can count the beats. 
     When a patient is admitted to a hospital, it is common for vital signs to be measured and recorded at regular intervals during the patient&#39;s stay to monitor their condition. A typical interval is 4 hours, which leads to the undesirable requirement for a nurse to awaken a patient in the middle of the night to take vital sign measurements. 
     When a patient is admitted to an ER, it is common for a nurse to do a “triage” assessment of the patient&#39;s condition that will determine how quickly the patient receives treatment. During busy times in an ER, a patient who does not appear to have a life-threatening injury may wait for hours until more-serious cases have been treated. While the patient may be reassessed at intervals while awaiting treatment, the patient may not be under observation between these reassessments. 
     Measuring certain vital signs is normally intrusive at best and difficult to do on a continuous basis. Measurement of body temperature, for example, is commonly done by placing an oral thermometer under the tongue or placing an infrared thermometer in the ear canal such that the tympanic membrane, which shared blood circulation with the brain, is in the sensor&#39;s field of view. Other countries report temperatures made by placing a thermometer under the arm, referred to as an “axillary” measurement as axilla is the Latin word for armpit. Skin temperature can be measured using a stick-on strip that may contain panels that change color to indicate the temperature of the skin below the strip. 
     Measurement of respiration is easy for a nurse to do, but relatively complicated for equipment to achieve. A method of automatically measuring respiration is to encircle the upper torso with a flexible band that can detect the physical expansion of the rib cage when a patient inhales. An alternate technique is to measure a high-frequency electrical impedance between two electrodes placed on the torso and detect the change in impedance created when the lungs fill with air. The electrodes are typically placed on opposite sides of one or both lungs, resulting in placement on the front and back or on the left and right sides of the torso, commonly done with adhesive electrodes connected by wires or by using a torso band with multiple electrodes in the strap. 
     Measurement of pulse is also relatively easy for a nurse to do and intrusive for equipment to achieve. A common automatic method of measuring a pulse is to use an electrocardiograph (ECG or EKG) to detect the electrical activity of the heart. An EKG machine may use up to 10 electrodes placed at defined points on the body to detect various signals associated with the heart function. Another common piece of equipment is simply called a “heart rate monitor.” Widely sold for use in exercise and training, heart rate monitors commonly consist of a torso band, in which are embedded two electrodes held against the skin and a small electronics package. Such heart rate monitors can communicate wirelessly to other equipment such as a small device that is worn like a wrist watch and that can transfer data wirelessly to a PC. 
     Nurses are expected to provide complete care to an assigned number of patients. The workload of a typical nurse is increasing, driven by a combination of a continuing shortage of nurses, an increase in the number of formal procedures that must be followed, and an expectation of increased documentation. Replacing the manual measurement and logging of vital signs with a system that measures and records vital signs would enable a nurse to spend more time on other activities and avoid the potential for error that is inherent in any manual procedure. 
     SUMMARY 
     For some or all of the reasons listed above, there is a need for a hospital or other caregiver facility to be able to continuously monitor its patients in different settings within the hospital. In addition, it is desirable for this monitoring to be done with limited interference with a patient&#39;s mobility or interfering with their other activities. 
     Embodiments of the patient monitoring system disclosed herein measure certain vital-sign readings of a patient, which can include respiratory rate, pulse rate, and body temperature, on a regular basis and compare these measurements to preset limits. 
     In addition, certain embodiments of the patient monitoring system disclosed herein can send alarm notifications to a hospital system if the vital-sign readings satisfy an alarm condition. It is desirable to reduce or eliminate false positives in the alarm notifications so as to avoid unnecessary trips or other actions of a healthcare provider that such false positives can cause. 
     In certain aspects of the present disclosure, a method of reducing false alarms associated with vital-sign monitoring is disclosed. The method comprises receiving one or more vital-sign readings of a patient. The method can further comprise receiving one or more acceleration readings from an accelerometer attached to the patient. The method can further comprise determining at least one of motion and position of the patient based at least in part on the one or more acceleration readings. The method can further comprise modifying an alarm condition determination procedure if at least one of the motion and the position satisfies a predefined condition. 
     In certain aspects of the present disclosure, a vital-sign monitoring system is provided that comprises a vital-sign monitor configured to monitor one or more vital signs of a patient. The system can further comprise a surveillance server configured to gather data relating to the one or more vital signs of the patient from the vital-sign monitor. The system can further comprise an accelerometer attached to the patient. The system can further comprise a processor in data communication with the vital-sign monitor and the accelerometer. The processor can be configured to receive one or more vital-sign readings of the patient, receive one or more acceleration readings from the accelerometer, determine at least one of motion and position of the patient based at least in part on the one or more acceleration readings, and modify an alarm condition determination procedure if at least one of the motion and the position satisfies a predefined condition. 
     It is understood that other configurations of the subject technology will become readily apparent to those skilled in the art from the following detailed description, wherein various configurations of the subject technology are shown and described by way of illustration. As will be realized, the subject technology is capable of other and different configurations and its several details are capable of modification in various other respects, all without departing from the scope of the subject technology. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide further understanding and are incorporated in and constitute a part of this specification, illustrate disclosed embodiments and together with the description serve to explain the principles of the disclosed embodiments. In the drawings: 
         FIG. 1  is a diagram illustrating an exemplary embodiment of a patient monitoring system according to certain aspects of the present disclosure. 
         FIG. 2A  is a perspective view of the vitals sign monitor patch shown in  FIG. 1  according to certain aspects of the present disclosure. 
         FIG. 2B  is a cross-sectional view of the vital signs patch shown in  FIGS. 1 and 2A  according to certain aspects of the present disclosure. 
         FIG. 2C  is a functional block diagram illustrating exemplary electronic and sensor components of the monitor patch of  FIG. 1  according to certain aspects of the present disclosure. 
         FIG. 3A  is a functional schematic diagram of an embodiment of the bridge according to certain aspects of the present disclosure. 
         FIG. 3B  is a functional schematic diagram of an embodiment of the surveillance server according to certain aspects of the present disclosure. 
         FIG. 4A  is a diagram depicting a patient wearing a temperature monitoring system comprising a monitor patch and a temperature probe and configured to measure body temperature of the patient according to certain aspects of the present disclosure. 
         FIG. 4B  is a diagram providing an enlarged view of the temperature monitoring system depicted in  FIG. 4A  according to certain aspects of the present disclosure. 
         FIG. 5  depicts a graph representing a series of data samples corresponding to a vital sign of a patient generated by a monitor patch according to certain aspects of the present disclosure. 
         FIG. 6  is a diagram depicting an exemplary vital-sign monitoring system that is configured to determine motion and/or position of a patient and thereby prevent or reduce false alarms associated with the patient motion/position according to certain aspects of the present disclosure. 
         FIG. 7  is a flowchart illustrating an exemplary process for determining motion or position of a patient and thereby preventing or reducing false alarms associated with the patient motion/position according to certain aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Continuous monitoring of patients in a hospital is desirable at least to ensure that patients do not suffer an un-noticed sudden deterioration in their condition or a secondary injury during their stay in the hospital. It is impractical to provide continuous monitoring by a clinician and cumbersome to connect sensors to a patient, which are then connected to a fixed monitoring instrument by wires. Furthermore, systems that sound an alarm when the measured value exceeds a threshold value may sound alarms so often and in situations that are not truly serious that such alarms are ignored by clinicians. 
     Measuring vital signs is difficult to do on a continuous basis. Accurate measurement of cardiac pulse, for example, can be done using an electrocardiograph (ECG or EKG) to detect the electrical activity of the heart. An EKG machine may use up to 10 electrodes placed at various points on the body to detect various signals associated with the heart function. Another common piece of equipment is termed a “heart rate monitor.” Widely sold for use in exercise and physical training, heart rate monitors may consist of a torso band in which are embedded two electrodes held against the skin and a small electronics package. Such heart rate monitors can communicate wirelessly to other equipment such as a small device that is worn like a wrist watch that can transfer data wirelessly to a personal computer (PC). 
     Certain exemplary embodiments of the present disclosure include a system that comprises a vital-signs monitor patch that is attached to the patient, and a bridge that communicates with monitor patches and links them to a central server that processes the data, where the server also sends data and alarms to the hospital system according to algorithms and protocols defined by the hospital. 
     The construction of the vital-signs monitor patch is described according to certain aspects of the present disclosure. As the patch may be worn continuously for a period of time that may be several days, as is described in the following disclosure, it is desirable to encapsulate the components of the patch such that the patient can bathe or shower and engage in their normal activities without degradation of the patch function. An exemplary configuration of the construction of the patch to provide a hermetically sealed enclosure about the electronics is disclosed. 
     In the following detailed description, numerous specific details are set forth to provide a full understanding of the present disclosure. It will be apparent, however, to one ordinarily skilled in the art that embodiments of the present disclosure may be practiced without some of the specific details. In other instances, well-known structures and techniques have not been shown in detail so as not to obscure the disclosure. 
       FIG. 1  discloses a vital sign monitoring system according to certain embodiments of the present disclosure. The vital sign monitoring system  12  includes vital-signs monitor patch  20 , bridge  40 , and surveillance server  60  that can send messages or interact with peripheral devices exemplified by mobile device  90  and workstation  100 . 
     Monitor patch  20  resembles a large adhesive bandage and is applied to a patient  10  when in use. It is preferable to apply the monitor patch  20  to the upper chest of the patient  10  although other locations may be appropriate in some circumstances. Monitor patch  20  incorporates one or more electrodes (not shown) that are in contact with the skin of patient  10  to measure vital signs such as cardiac pulse rate and respiration rate. Monitor patch  20  also may include other sensors such as an accelerometer or a temperature sensor to measure other characteristics associated with the patient. Monitor patch  20  also includes a wireless transmitter that can both transmit and receive signals. This transmitter is preferably a short-range, low-power radio frequency (RF) device operating in one of the industrial, scientific and medical (ISM) radio bands. One ISM band in the United States (US) is, for example, centered at 915 MHz. An example of an equivalent band in the European Union (EU) is centered at 868 MHz. Other frequencies of operation may be possible dependent upon local regulations and interference from other wireless devices. 
     Surveillance server  60  may be a standard computer server connected to the hospital communication network and preferably located in the hospital data center or computer room, although other locations may be employed. The server  60  stores and processes signals related to the operation of the patient monitoring system  12  disclosed herein including the association of individual monitor patches  20  with patients  10  and measurement signals received from multiple monitor patches  20 . Hence, although only a single patient  10  and monitor patch  20  are depicted in  FIG. 1 , the server  60  is able to monitor the monitor patches  20  for multiple patients  10 . 
     Bridge  40  is a device that connects, or “bridges”, between monitor patch  20  and server  60 . Bridge  40  communicates with monitor patch  20  over communication link  30  operating, in these exemplary embodiments, at approximately 915 MHz and at a power level that enables communication link  30  to function up to a distance of approximately 3 meters. It is preferable to place a bridge  40  in each room and at regular intervals along hallways of the healthcare facility where it is desired to provide the ability to communicate with monitor patches  20 . Bridge  40  also is able to communicate with server  60  over network link  50  using any of a variety of computer communication systems including hardwired and wireless Ethernet using protocols such as 802.11a/big or 802.3af. As the communication protocols of communication link  30  and network link  50  may be very different, bridge  40  provides data buffering and protocol conversion to enable bidirectional signal transmission between monitor patch  20  and server  60 . 
     While the embodiments illustrated by  FIG. 1  employ a bridge  20  to provide communication link between the monitor patch  20  and the server  60 , in certain alternative embodiments, the monitor patch  20  may engage in direct wireless communication with the server  60 . In such alternative embodiments, the server  60  itself or a wireless modern connected to the server  60  may include a wireless communication system to receive data from the monitor patch  20 . 
     In use, a monitor patch  20  is applied to a patient  10  by a clinician when it is desirable to continuously monitor basic vital signs of patient  10  while patient  10  is, in this embodiment, in a hospital. Monitor patch  20  is intended to remain attached to patient  10  for an extended period of time, for example, up to 5 days in certain embodiments, limited by the battery life of monitor patch  20 . In some embodiments, monitor patch  20  is disposable when removed from patient  10 . 
     Server  60  executes analytical protocols on the measurement data that it receives from monitor patch  20  and provides this information to clinicians through external workstations  100 , preferably personal computers (PCs), over the hospital network  70 . Server  60  may also send messages to mobile devices  90 , such as cell phones or pagers, over a mobile device link  80  if a measurement signal exceeds specified parameters. Mobile device link  80  may include the hospital network  70  and internal or external wireless communication systems that are capable of sending messages that can be received by mobile devices  90 . 
       FIG. 2A  is a perspective view of the vital-signs monitor patch  20  shown in  FIG. 1  according to certain aspects of the present disclosure. In the illustrated embodiment, the monitor patch  20  includes component carrier  23  comprising a central segment  21  and side segments  22  on opposing sides of the central segment  21 . In certain embodiments, the central segment  21  is substantially rigid and includes a circuit assembly ( 24 ,  FIG. 2B ) having electronic components and battery mounted to a rigid printed circuit board (PCB). The side segments  22  are flexible and include a flexible conductive circuit ( 26 ,  FIG. 2B ) that connect the circuit assembly  24  to electrodes  28  disposed at each end of the monitor patch  20 , with side segment  22  on the right shown as being bent upwards for purposes of illustration to make one of the electrodes  28  visible in this view. 
       FIG. 2B  is a cross-sectional view of the vital-signs patch  20  shown in  FIGS. 1 and 2A  according to certain aspects of the present disclosure. The circuit assembly  24  and flexible conductive circuit  26  described above can be seen herein. The flexible conductive circuit  26  operably connects the circuit assembly  24  to the electrodes  28 . Top and bottom layers  23  and  27  form a housing  25  that encapsulate circuit assembly  28  to provide a water and particulate barrier as well as mechanical protection. There are sealing areas on layers  23  and  27  that encircles circuit assembly  28  and is visible in the cross-section view of  FIG. 2B  as areas  29 . Layers  23  and  27  are sealed to each other in this area to form a substantially hermetic seal. Within the context of certain aspects of the present disclosure, the term ‘hermetic’ implies that the rate of transmission of moisture through the seal is substantially the same as through the material of the layers that are sealed to each other, and further implies that the size of particulates that can pass through the seal are below the size that can have a significant effect on circuit assembly  24 . Flexible conductive circuit  26  passes through portions of sealing areas  29  and the seal between layers  23  and  27  is maintained by sealing of layers  23  and  27  to flexible circuit assembly  28 . The layers  23  and  27  are thin and flexible, as is the flexible conductive circuit  26 , allowing the side segment  22  of the monitor patch  20  between the electrodes  28  and the circuit assembly  24  to bend as shown in  FIG. 2A . 
       FIG. 2C  is a functional block diagram  200  illustrating exemplary electronic and sensor components of the monitor patch  20  of  FIG. 1  according to certain aspects of the present disclosure. The block diagram  200  shows a processing and sensor interface module  201  and external sensors  232 ,  234  connected to the module  201 . In the illustrated example, the module  201  includes a processor  202 , a wireless transceiver  207  having a receiver  206  and a transmitter  209 , a memory  210 , a first sensor interface  212 , a second sensor interface  214 , a third sensor interface  216 , and an internal sensor  236  connected to the third sensor interface  216 . The first and second sensor interfaces  212  and  214  are connected to the first and second external sensors  232 ,  234  via first and second connection ports  222 ,  224 , respectively. In certain embodiments, some or all of the aforementioned components of the module  201  and other components are mounted on a PCB. 
     Each of the sensor interfaces  212 ,  214 ,  216  can include one or more electronic components that are configured to generate an excitation signal or provide DC power for the sensor that the interface is connected to and/or to condition and digitize a sensor signal from the sensor. For example, the sensor interface can include a signal generator for generating an excitation signal or a voltage regulator for providing DC power to the sensor. The sensor interface can further include an amplifier for amplifying a sensor signal from the sensor and an analog-to-digital converter for digitizing the amplified sensor signal. The sensor interface can further include a filter (e.g., a low-pass or bandpass filter) for filtering out spurious noises (e.g., a 60 Hz noise pickup). 
     The processor  202  is configured to send and receive data (e.g., digitized signal or control data) to and from the sensor interfaces  212 ,  214 ,  216  via a bus  204 , which can be one or more wire traces on the PCB. Although a bus communication topology is used in this embodiment, some or all communication between discrete components can also be implemented as direct links without departing from the scope of the present disclosure. For example, the processor  202  may send data representative of an excitation signal to the sensor excitation signal generator inside the sensor interface and receive data representative of the sensor signal from the sensor interface, over either a bus or direct data links between processor  202  and each of sensor interface  212 ,  214 , and  216 . 
     The processor  202  is also capable of communication with the receiver  206  and the transmitter  209  of the wireless transceiver  207  via the bus  204 . For example, the processor  202  using the transmitter and receiver  209 ,  206  can transmit and receive data to and from the bridge  40 . In certain embodiments, the transmitter  209  includes one or more of an RF signal generator (e.g., an oscillator), a modulator (a mixer), and a transmitting antenna; and the receiver  206  includes a demodulator (a mixer) and a receiving antenna which may or may not be the same as the transmitting antenna. In some embodiments, the transmitter  209  may include a digital-to-analog converter configured to receive data from the processor  202  and to generate a base signal; and/or the receiver  206  may include an analog-to-digital converter configured to digitize a demodulated base signal and output a stream of digitized data to the processor  202 . 
     The processor  202  may include a general-purpose processor or a specific-purpose processor for executing instructions and may further include a memory  219 , such as a volatile or non-volatile memory, for storing data and/or instructions for software programs. The instructions, which may be stored in a memory  219  and/or  210 , may be executed by the processor  202  to control and manage the wireless transceiver  207 , the sensor interfaces  212 ,  214 ,  216 , as well as provide other communication and processing functions. 
     The processor  202  may be a general-purpose microprocessor, a microcontroller, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a Programmable Logic Device (PLD), a controller, a state machine, gated logic, discrete hardware components, or any other suitable device or a combination of devices that can perform calculations or other manipulations of information. 
     Information, such as program instructions, data representative of sensor readings, preset alarm conditions, threshold limits, may be stored in a computer or processor readable medium such as a memory internal to the processor  202  (e.g., the memory  219 ) or a memory external to the processor  202  (e.g., the memory  210 ), such as a Random Access Memory (RAM), a flash memory, a Read Only Memory (ROM), a Programmable Read-Only Memory (PROM), an Erasable PROM (EPROM), registers, a hard disk, a removable disk, or any other suitable storage device. 
     In certain embodiments, the internal sensor  236  can be one or more sensors configured to measure certain properties of the processing and sensor interface module  201 , such as a board temperature sensor thermally coupled to a PCB. In other embodiments, the internal sensor  236  can be one or more sensors configured to measure certain properties of the patient  10 , such as a motion sensor (e.g., an accelerometer) for measuring the patient&#39;s motion. 
     The external sensors  232 ,  234  can include sensors and sensing arrangements that are configured to produce a signal representative of one or more vital signs of the patient to which the monitor patch  20  is attached. For example, the first external sensor  232  can be a set of sensing electrodes that are affixed to an exterior surface of the monitor patch  20  and configured to be in contact with the patient for measuring the patient&#39;s respiratory rate, and the second external sensor  234  can include a temperature sensing element (e.g., a thermocouple or a thermistor) affixed, either directly or via an interposing layer, to skin of the patient  10  for measuring the patient&#39;s body temperature. In other embodiments, one or more of the external sensors  232 ,  234  or one or more additional external sensors can measure other vital signs of the patient, such as blood pressure and pulse rate. 
       FIG. 3A  is a functional block diagram illustrating exemplary electronic components of bridge  40  of  FIG. 1  according to one aspect of the subject disclosure. Bridge  40  includes a processor  310 , radio  320  having a receiver  322  and a transmitter  324 , radio  330  having a receiver  332  and a transmitter  334 , memory  340 , display  345 , and network interface  350  having a wireless interface  352  and a wired interface  354 . In some embodiments, some or all of the aforementioned components of module  300  may be integrated into single devices or mounted on PCBs. 
     Processor  310  is configured to send data to and receive data from receiver  322  and transmitter  324  of radio  320 , receiver  332  and transmitter  334  of radio  330  and wireless interface  352  and wired interface  354  of network interface  350  via bus  314 . In certain embodiments, transmitters  324  and  334  may include a radio frequency signal generator (oscillator), a modulator, and a transmitting antenna, and the receivers  322  and  332  may include a demodulator and antenna which may or may not be the same as the transmitting antenna of the radio. In some embodiments, transmitters  324  and  334  may include a digital-to-analog converter configured to convert data received from processor  310  and to generate a base signal, while receivers  322  and  332  may include analog-to-digital converters configured to convert a demodulated base signal and sent a digitized data stream to processor  310 . 
     Processor  310  may include a general-purpose processor or a specific-purpose processor for executing instructions and may further include a memory  312 , such as a volatile or non-volatile memory, for storing data and/or instructions for software programs. The instructions, which may be stored in memories  312  or  340 , may be executed by the processor  310  to control and manage the transceivers  320 ,  330 , and  350  as well as provide other communication and processing functions. 
     Processor  310  may be a general-purpose microprocessor, a microcontroller, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a Programmable Logic Device (PLD), a controller, a state machine, gated logic, discrete hardware components, or any other suitable device or a combination of devices that can perform calculations or other manipulations of information. 
     Information such as data representative of sensor readings may be stored in memory  312  internal to processor  310  or in memory  340  external to processor  310  which may be a Random Access Memory (RAM), flash memory, Read Only Memory (ROM), Programmable Read Only Memory (PROM), Erasable Programmable Read Only Memory (EPROM), registers, a hard disk, a removable disk, a Solid State Memory (SSD), or any other suitable storage device. 
     Memory  312  or  340  can also store a list or a database of established communication links and their corresponding characteristics (e.g., signal levels) between the bridge  40  and its related monitor patches  20 . In the illustrated example of  FIG. 3A , the memory  340  external to the processor  310  includes such a database  342 ; alternatively, the memory  312  internal to the processor  310  may include such a database. 
       FIG. 3B  is a functional block diagram illustrating exemplary electronic components of server  60  of  FIG. 1  according to one aspect of the subject disclosure. Server  60  includes a processor  360 , memory  370 , display  380 , and network interface  390  having a wireless interface  392  and a wired interface  394 . Processor  360  may include a general-purpose processor or a specific-purpose processor for executing instructions and may further include a memory  362 , such as a volatile or non-volatile memory, for storing data and/or instructions for software programs. The instructions, which may be stored in memories  362  or  370 , may be executed by the processor  360  to control and manage the wireless and wired network interfaces  392 ,  394  as well as provide other communication and processing functions. 
     Processor  360  may be a general-purpose microprocessor, a microcontroller, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a Programmable Logic Device (PLD), a controller, a state machine, gated logic, discrete hardware components, or any other suitable device or a combination of devices that can perform calculations or other manipulations of information. 
     Information such as data representative of sensor readings may be stored in memory  362  internal to processor  360  or in memory  370  external to processor  360  which may be a Random Access Memory (RAM), flash memory, Read Only Memory (ROM), Programmable Read Only Memory (PROM), Erasable Programmable Read Only Memory (EPROM), registers, a hard disk, a removable disk, a Solid State Memory (SSD), or any other suitable storage device. 
     Memory  362  or  370  can also store a database of communication links and their corresponding characteristics (e.g., signal levels) between monitor patches  20  and bridges  40 . In the illustrated example of  FIG. 3B , the memory  370  external to the processor  360  includes such a database  372 ; alternatively, the memory  362  internal to the processor  360  may include such a database. 
     As indicated above with respect to  FIG. 2C , certain embodiments of the monitor patch  20  are configured to operate with external sensors that are in turn configured to produce a signal representative of one or more vital signs of the patient to whom the monitor patch  20  is attached. For example, the second external sensor  234  can be a temperature probe that includes a temperature sensing element (e.g., a thermocouple or thermistor) affixed, either directly or via an interposing layer, to skin of the patient  10  for measuring the patient&#39;s body temperature.  FIG. 4A  is a diagram depicting a patient  10  wearing a temperature monitoring system  20 A comprising a monitor patch  20  and a temperature probe  400  that is configured to measure body temperature of the patient  10 . In the illustrated example, the temperature probe  400  is configured for axillary temperature sensing of the patient  10  to whom the monitor patch  20  is attached. The monitor patch  20  is attached to the chest  11  of the patient  10 , with a sensing portion of the temperature probe  400  retained in the axilla  12  of the patient  10  during body temperature monitoring. 
       FIG. 4B  is a diagram providing an enlarged view of the monitoring system  20 A depicted in  FIG. 4A  according to certain aspects of the present disclosure. As indicated above, the monitor patch  20  is attached to the chest  11  of the patient  10  via, e.g., an adhesive backing (not shown). The temperature probe  400  has a proximal end  401  and a distal end  403  and includes a wiring portion  410 , a body connection portion  430 , and a sensing portion  420  disposed between the wiring and body connection portions  410 ,  430 . The proximal end  401  of the temperature probe  400  is connected to the monitor patch  20  at its connection port  22 . In certain embodiments, the proximal end  401  of the temperature probe  400  is removably attached (e.g., plugged) to the monitor patch  20 . In other embodiments, the proximal end  401  is fixedly attached (e.g., epoxied or fused) to the monitor patch  20 . 
     The sensing portion  420  of the temperature probe  400  is configured for placement within the axilla  12  of the patient  10  and includes a temperature sensing element (e.g.,  234 A-D of  FIGS. 5A-D  and  234 E-F of  FIGS. 6A-B ). The wiring portion  410  of the temperature probe  400  includes one or more electrical conductors ( 512 ,  514  of  FIGS. 5A-D  and  FIGS. 6A-B ) for carrying a signal responsive to a change in body temperature of the patient  10  between the temperature sensing element  234  and the monitor patch  20 . In the illustrated example, the wiring portion  410  includes a flexible cable comprising a tubing and electrical conductors (e.g., a pair of twisted copper wires) placed within the tubing. The wiring portion  410  includes a coiled section  414  acting as a spring to take up any slack in the cable so as to accommodate patients of different sizes. In the illustrated example, the monitoring system  20 A further includes an adhesive element  416  (e.g., a tape) coupled to the cable and configured to attach the wiring portion  410  of the cable to the patient&#39;s body, e.g., at a point between the chest  11  and the armpit  12  of the patient. 
     The body connection portion  430  has one end connected to the sensing portion  420  and is configured to be attached to another body portion of the patient  10  such that the sensing portion  420  of the temperature probe  400  can be retained within the axilla  12  of the patient  10 . In the illustrated example, such attachment is achieved via an adhesive element  426  (e.g., a tape) coupled to the distal end of the body connection portion  430 . The coupled adhesive element  426  is then attached to a second body portion  13  (e.g., the back of the patient&#39;s arm) of the patient  10 . 
     A multitude of modifications and additions to the illustrated embodiment of  FIG. 4B  are possible without departing from the scope of the disclosure. For example, the body connection portion  430  of the temperature probe  400  can include one or more coiled sections acting as a spring similar to the coiled section  414  of the wiring portion  410 . The adhesive element  416  may be coupled to the body connection portion  430  at a point different than the distal end of the body connection portion  430 . In certain embodiments, entirely different means of attaching the body connection portion  430  to the patient&#39;s body may be used. For example, the body connection portion  430  may itself be in the form of an adhesive tape that can stick to the body of the patient  10  or may include an elastic loop (e.g., a rubber band) to be placed around the patient&#39;s arm. 
     While the temperature probe  400  in the illustrated embodiments of  FIGS. 4A-B  is shown to be operatively coupled to a vital-sign monitor patch worn by the patient  10 , the temperature probe  400  may be alternatively operatively coupled to other types of monitoring devices such as a stationary monitoring unit located near the patient&#39;s hospital bed. Such a stationary monitoring unit can take readings of the patient&#39;s body temperature based on a signal from the temperature probe  400  and send the temperature readings to a surveillance server via a wired or wireless connection and make other decisions such as providing an indication of an alarm condition (e.g., a high body temperature condition or a loss of thermal contact between the temperature probe and the patient). 
     As indicated above, in certain aspects, the vital-signs monitoring system (e.g., the monitoring system  12  of  FIG. 1 ) of the present disclosure can be configured to sound an alarm when one or more vital-sign readings exceed an alarm threshold limit. For example, the surveillance server  60  can receive vital-sign readings (e.g., body temperature values or heart rate values) from the monitor patch  20 , either directly or via the bridge  40 , and, if the vital-sign readings satisfy an alarm condition, e.g., by exceeding an alarm threshold limit for a certain predetermined number of samples, send an alarm notification to the hospital system  100 . 
       FIG. 5  depicts a graph  500  representing a series of data samples (solid dots) corresponding to vital-sign readings of a patient generated by a monitor patch  20  according to certain aspects of the present disclosure. The vital-sign readings can represent, for example, body temperature or heart rate of the patient. The graph  500  shows two threshold limits: a first threshold limit  501  (the “yellow limit”) and a second threshold limit  502  (the “red limit”). The first threshold limit  501  can correspond to an alert or warning threshold limit, whereas the second threshold limit  502  can correspond to an alarm threshold limit. The exemplary graph  500  is divided into three regions: a first region  504 , a second region  506 , and a third region  508 . In the first region  504 , the vital-sign readings are below the first threshold limit  501 , and the monitoring system is in its normal mode of operation. In the normal mode of operation, vital-sign readings  511 - 513  are generated at the monitor patch  20  and sent to the surveillance server  60  at a first (slow) sampling rate. The surveillance server  60  stores the received vital-sign readings  511 - 513  in a database and/or forwards them to a hospital system (e.g., workstation  100  of  FIG. 1 ) to be displayed at the first sampling rate. 
     In the second region  506 , entered after the vital-sign readings exceed the first (alert) threshold limit  501 , the monitoring system is in an alert mode of operation. In the alert mode of operation, vital-sign readings  514 - 545  are generated at the monitor patch  20  and sent to the surveillance server  60  at a second (fast) rate. The surveillance server  60  can store the received vital-sign readings  514 - 545  to a database and/or forward them to the hospital system  100  to be displayed at the second sampling rate. In addition, the surveillance server  60  can also send alarm notifications to the hospital system  100  when the vital-sign reading exceed the second (alarm) threshold limit  502  and stay above the limit for a predetermined number of samples. Such alarm notifications may be sent each time the reading exceeds the second threshold limit  502  or after every M consecutive times the readings stay above the second threshold limit  502 , where M is an integer greater than 1. 
     In the third region  508 , entered after the vital-sign readings have fallen and stayed below the first threshold limit  501  for N number of times, where N is a positive integer (e.g.,  1 - 4 ), the monitoring system has reverted back to the normal mode of operation, where vital-sign readings are generated at the monitor patch  20  and sent to the surveillance server  60  at the first (slow) sampling rate again. 
     For a number of reasons, a vital sign monitoring system may sound so called “false” or “nuisance” alarms when such alarms are not warranted. Under certain circumstances, the system may sound false alarms so often and in situations that are not truly serious that such alarms may start to be ignored by clinicians, thereby creating the “cry wolf” syndrome where an alarm caused by a true emergency situation may be also ignored. One source of false alarms is motion of a patient to whom the monitor, patch  20  is attached. It is known that motion associated with certain types of physical activity by the patient can lead to variations in vital-sign readings. For example, a brisk walking by the patient, e.g., down the hall or on a treadmill, can cause an increase in the heart rate and respiratory rate of the patient, and the rates can eventually exceed respective alarm threshold limits, thereby setting off alarms. However, in most cases, such a temporary motion-related increase in a vital-sign value has no clinical significance and may be safely ignored. 
     Motion of a patient can cause a false alarm not only through an increase in a vital-sign reading but also through so-called “motion artifacts” that the motion can generate. For example, a twisting or stretching motion, e.g., during a vigorous exercise by the patient, can cause changes in the spacing between the respiratory-rate monitoring electrodes in the monitor patch  20 , and such changes in the inter-electrode spacing can produce spurious spikes in the measured respiratory-rate readings. These same movements can also generate forces on the electrodes. The electrode-skin electrical interface is very sensitive to any force being applied in that area, either shear, tension or compression forces relative to skin-electrode plane. This can have a significant impact on the electrical signal for both ECG and impedance pneumography. 
     Furthermore, position (postural orientation) of the patient can also affect the measured vital-sign readings. For example, a patient lying on his or her side or in a prone position on the bed can put a stress or strain on a sensing element of the monitor patch, and the stress or strain can cause a vital-sign reading to increase beyond a high alarm threshold limit set or decrease below a low alarm threshold limit. Motional or positional disruptions can also cause false positives, as mentioned above, but also false negatives. Signal can be disrupted in such a way that the reading appears normal while actual vital signs call for critical medical attentions. For example, a reading could be affected by the patient movement in such a way that the false value being sent falls into a safe domain while the actual vital sign value is outside the safe domain. In this case, no alarm is sent while the condition of the patient requires it. 
     In addition, random movements (e.g. dressing/undressing, rolling in a bed) has a tendency to diminish the quality of the signal, leading to potentially less accurate values. Cyclic movements (walking, combing hair, turning pages of a book) would have the effect of creating changes in impedance which could be mistaken for breaths. This can lead to a wrong value being sent. This second situation is particularly difficult to identify as the impedance patterns could look very similar to those related to respiration, for example. 
     If motion and/or position (motion/position) of the patient wearing the monitor patch  20  can be determined, however, false alarms or false negatives due to motion/position artifacts or clinically-insignificant temporary motion/position-related changes to vital-sign readings may be prevented or at least reduced, for example, by recognizing and ignoring samples plagued by motion/position-related artifacts or adjusting one or more alarm threshold limits accordingly. 
       FIG. 6  is a diagram depicting an exemplary vital-sign monitoring system  600  that is configured to determine motion and/or position of a patient (hereinafter the “patient motion/position”) and thereby prevent or reduce false alarms associated with the patient motion/position according to certain aspects of the present disclosure. The system  600  includes a monitor patch  20 B, a bridge  40 , a surveillance server  60 , and a hospital system  100 . The monitor patch  20 B includes a vital-sign sensing module  601 , an accelerometer  602 , a processor  202 , and a wireless transceiver  207 . With reference to  FIG. 2C , the vital-sign sensing module  602  can include one or more vital-sign sensors  232 ,  234 , such as electrodes for measuring respiration and temperature sensing elements, and sensor interfaces  212 ,  214  for conditioning and converting signals from the sensors  332 ,  234 . The vital-sign sensing module  601  provides one or more vital-sign outputs  621  responsive to changes in one or more vital signs of the patient  10 . 
     In certain embodiments, the accelerometer  602  is a three-axis accelerometer (TA) configured to provide three outputs  621 ,  622 ,  623  responsive to accelerations in three orthogonal directions, e.g., x, y, and z-directions  611 ,  612 , and  613 . The outputs  621 ,  622 ,  623  may be analog or digital signals. An example of a three-axis accelerometer that can be employed is a three-axis linear accelerometer (Model No. LIS302DL) manufactured by STMicroelectronics, which provides selectable full scales of +/−2 g and +/−8 g. In the illustrated example, the x-direction  611  is along the length direction of the monitor patch  20 B; the y-direction  612  is perpendicular to the upper surface of the monitor patch  20 B, and the z-direction  613  is along the width direction of the monitor patch  20 B. The TA  602  produces three outputs: x output  631 , y output  632 , and z output  633 , corresponding to measured accelerations in the x-, y- and z-directions  611 ,  612 ,  613 , respectively. 
     In certain embodiments of the monitor patch  20 B, the processor  202  is configured (e.g., programmed) to receive the one or more vital-sign outputs  621  from the vital-sign sensing module  601  and the x, y, z outputs  631 ,  632 ,  633  from the TA  602  and determine (e.g., calculate or look up) vital-sign readings and x-, y-, and z-acceleration readings from the received vital-sign and acceleration outputs. Given the geometry of the illustrated example, the x-acceleration reading is indicative of the acceleration that the patient  10  is subjected to along the width (e.g., side-to-side) direction of the patient  10 , the y-acceleration reading is indicative of the acceleration that the patient  10  is subjected to along the thickness (e.g., front-to-back) direction of the patient  10 , and the z-acceleration reading is indicative of the acceleration the patient  10  is subjected to along the height (e.g., head-to-toe) direction of the patient  10 . For example, if the patient  10  were standing up still as in the illustrated example of  FIG. 6 , the x-, y-, z-acceleration readings, normalized to the Earth&#39;s gravitational acceleration (g), would be (0, 0, 1). If the patient  10  were lying in a prone (facing down) position or in a supine (facing up) position, the normalized acceleration readings would be (0, −1, 0). The processor  202  of the monitor patch  20 B is further configured to send the vital-sign readings and the x-, y-, and z-acceleration readings to the surveillance server  60 , either directly or via bridge  40 . 
     At the surveillance server  60 , a processor (e.g.,  360  of  FIG. 3B  or  202  of  FIG. 6 ) is configured (e.g., programmed) to execute a program stored in a memory (either inside or outside the processor  360 ,  202 ) and to receive the vital-sign and acceleration readings from the monitor patch  20 B. The processor  360 ,  202  is further configured to determine one or both of motion and position of the patient  10  (patient motion/position) after applying one or more motion/position determination algorithms to the acceleration readings. The processor  360 ,  202  is further configured to modify an alarm condition determination procedure if the motion/position determination satisfies a predefined condition. The modification to the alarm condition determination procedure can include adjusting one or more alarm threshold limits to account for the likely outcome that the patient motion/position would cause changes in the vital-sign readings, where the changes (e.g., increases) do not have any clinical significance for the patent. The modification can further exclude one or more vital-sign reading from the alarm condition determination procedure if it is determined that the patient motion/position is likely to cause artifacts (e.g., spikes) in the readings or generate a band reading movement because, for example, the patient movement can be mistaken for respiration. In certain embodiments, acceleration readings can also be used to provide input to a noise filtering algorithm allowing for a better filtering of cyclic movements. For example, knowing the frequency of the gait of a patient who is walking could allow excluding that particular harmonic from an impedance signal. 
     Regarding the patient&#39;s position (e.g., postural orientation), the processor  360  can determine whether the patient is in a prone, sitting, or standing position, e.g., from the relative values of the x-, y-, and z-acceleration readings. In some embodiments, if the processor  360  determines that the patient  10  is in a prone position, the processor  360  further determines whether the patient  10  is lying in a supine or prone position on his/her front, back or side (right or left). 
     Regarding the patent&#39;s motion, the processor  360  can determine whether the patient is in engaged in motion or is at rest from the x-, y-, and z-acceleration readings. One suitable measure of such motion/rest determination can be the normal signal magnitude area (SMA). Defined in (1), the SMA can be used as the basis for identifying periods of motion or activity: 
     
       
         
           
             
               
                 
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     where x(t), y(t), and z(t) refer to the body components of the x-, y-, and z-accelerations, respectively. By way of example, calculation of this parameter can be performed by summing each sampled value progressively (e.g., following the digitization of each accelerometer sample) over a 1-s interval. The SMA value is compared to an appropriate activity threshold value, which can be theoretically or experimentally determined. If the SMA value is at or above the activity threshold value, the patient  10  is deemed to be engaged in a motion, whereas, if the SMA value is below the activity threshold value, the patient  10  is deemed to be at rest. 
     When the processor  360  determines that the patient  10  is engaged in motion, the processor  360  can further determine whether the patient&#39;s motion is active or passive, meaning whether the patient  10  is moving (e.g., ambulating) or is being moved (e.g., on a patient carrier or a motorized wheelchair). This determination can be performed by analyzing a combination of motion and position information derived from the acceleration readings. For example, if the acceleration readings indicate that the patient  10  is moving along the z-direction, while the y-direction acceleration indicates that the patient  10  is lying down in a prone position, the processor  360  can determine that the patient  10  is being moved while lying down on a patient carrier and, accordingly, determine that the patient&#39;s motion is passive. If the processor  360  determines that the patient&#39;s motion is passive, the processor  360  applies a standard alarm condition determination procedure, an example of which was described above with respect to  FIG. 5 , without any modification to the procedure. 
     On the other hand, if the processor  360  determines that the patient&#39;s motion is active and that the patient&#39;s active motion is of the type and intensity that is likely to cause one or more vital-sign readings (e.g., heart rate) of the patient  10  to exceed the currently active standard alarm threshold limit and trigger an alarm without having any clinical significance to the patient, the processor  360  makes a modification to the alarm condition determination procedure, e.g., by increasing the alarm threshold limit (e.g., the second threshold limit  502  of  FIG. 5 ). In certain embodiments, the amount of increase for the alarm threshold limit can fixed (e.g., 10%). In other embodiments, the amount of increase is linearly proportional to or is another increasing function that depends on the level of a patient&#39;s physical activity as determined by the acceleration readings and a total duration of the physical activity. In yet other embodiments, the motion is classified into different activity categories, and the amount of increase is determined based on the classified activity category. For example, the patent&#39;s active ambulatory motion may be classified into one of: 1) slow walking; 2) normal walking; 3) fast walking; and 4) running. Depending on the activity category for the patient&#39;s motion (and in some cases, duration thereof), the processor  360  can increase the alarm threshold limit by different amounts. 
     In some embodiments, the processor  360  determines that a change in the patient motion/position has occurred. For example, the processor  360  may determine that the patient  10  has changed from sitting to standing positions (sit-to-stand), from standing to sitting positions (stand-to-sit), prone to sit positions (prone-to-sit), or sit to prone positions (sit-to-prone). Such positional change determination may involve the processor  360  analyzing changes in the acceleration readings and finding certain known patterns that signify one of the positional changes listed above. Such positional change information may be used as time-markers to start a clock. For example, when a patient stands up from a bench and starts to walk briskly down a hall, the sit-to-stand change can start a timer for measuring the duration of the physical activity, which duration can be used for calculating the amount of increase for the alarm threshold limit. 
     In some embodiments, if the processor  360  determines that the patient  10  is engaged in a type of motion (e.g., running) and/or is in a position (e.g., lying on the front, back or side) that is likely to produce motion/position-related artifacts or difficulties for the system to acquire an accurate reading when the patient maintains a specific position (e.g., by putting stress or strain on a sensing element of the patch  20 B or by generating changes in impedance which are not related to respiration), the processor  360  excludes all or some of the received vital-sign readings from the alarm condition determination procedure or refrains from sending an alarm notification to hospital system  100  even if the vital-sign readings exceed the alarm threshold limit. 
     In certain embodiments, the processor  360  may perform a check across readings for different vital-signs signs to rule out possible false positives in the patient motion/position determination. For example, assume that the motion/position determination procedure indicates that the patient  10  is engaged in a type of activity (e.g., running) that is likely to substantially increase both the heart rate and the respiratory rate of the patient  10 . If the vital-sign readings indicate, however, that only the respiratory rate, but not the heart rate, has increased, the processor  360  may determine that the increase in the heart rate is not motion-related and decide not to modify the alarm determination procedure (e.g., increase the alarm threshold limit) for the heart rate. By performing such a cross checking based on different vital-sign readings, the motion/position determination procedure itself may be verified, thereby increasing the reliability of the procedure for preventing or reducing false alarms. 
     It shall be appreciated that a multitude of modifications to the patient monitoring system  600  described above are possible without departing from the scope of the present disclosure. For example, while the accelerometer  602  in the exemplary embodiment of  FIG. 6  provides outputs  631 ,  632 ,  633  in three Cartesian-coordinate directions (e.g., x, y, and z), in alternative embodiments, the accelerometer  602  may provide only one or two outputs (e.g., along z only or in x and y). In other alternative embodiments, the accelerometer  602  may provide three outputs in three cylindrical-coordinate directions (e.g., r, θ, and z) or spherical-coordinate directions (e.g., r, θ, and φ). While the accelerometer  602  is part of the monitor patch  20 B in the exemplary embodiment of  FIG. 6 , in alternative embodiments, the accelerometer may be detached from the monitor patch  20 B and communicate one or more acceleration outputs to the monitor patch  20 B via wired or wireless connections. 
     In some embodiments, the motion/position determination procedure may be performed by the processor  202  in the motion patch  20 B instead of the processor  360  in the surveillance server  60 . In those embodiments, the processor  202 , upon determining a patient motion/position that requires a modification to the alarm condition determination procedure, may send a message indicative of such motion/position determination to the surveillance server  60 . In addition, the processor  202  of the monitor patch  20 B, upon determining that the patient  10  is engaged in a motion or in a position that is likely to produce artifacts in vital-sign readings, may choose not to send the vital-sign readings while such a patient motion/position persists. 
     In certain embodiments, the acceleration readings can be used to search for acceleration patterns which are typically associated with respiration (e.g. cyclic accelerations along an horizontal axis pointing in front of the patient). This approach, as well the other methods of filtering some harmonics (described in a comment above), can generate a completely different process flow than the one presented in  FIG. 7 . In those two cases, acceleration readings can be used to help improve signal processing, as opposed to other methods described here where they are use only to improve the way vital sign readings are generating alarms. 
       FIG. 7  is a flowchart illustrating an exemplary process  700  for determining motion or position of a patient and thereby preventing or reducing false alarms associated with the patient motion/position according to certain aspects of the present disclosure. For ease of illustration, without any intent to limit the scope of the present disclosure in any way, the process  700  will be described with reference to the exemplary patient monitoring system  600  of  FIG. 6 . The process  700  begins at start state  701  and proceeds to operations  710  and  720  in which new sets of vital-sign readings and acceleration readings generated at and sent from the monitor patch  20 B are received by the surveillance server  60 . While the reception of vital-sign readings (operation  710 ) is shown as being performed prior to the reception of acceleration readings (operation  720 ) in the exemplary process  700  of  FIG. 7 , in alternative processes, the reception of acceleration readings by the surveillance server  60  may take place prior to or at the same time as the reception of the vital-sign readings. The frequency of the reception of acceleration readings may be the same or different from the frequency of the reception of the vital-sign readings. For example, the vital-sign readings may be received every 10 minutes while the acceleration readings may be received every 30 seconds during the normal mode of operation for the monitoring system. A high-frequency reception of the acceleration readings allows for determination of a position change (e.g., sit-to-stand) of the patient, for example. 
     The process  700  proceeds to operation  730  in which the patient motion/position is determined based at least in part on the received acceleration readings. Various types of motions and/or positions that may be so determined and methods by which such determination may be made are described above with respect to  FIG. 6  and are not repeated here. 
     The process  700  proceeds to decision state  740  in which it is determined whether the patient motion/position determined at the operation  730  is likely to produce motion/position-related artifacts. Examples of such motions and positions that are likely to produce artifacts include, but are not limited to: twisting, stretching, lying in a prone position on the front or side, dressing/undressing, rolling in a bed, and showering. If the answer to the determination at the decision state  740  is YES (the patient motion/position likely to produce artifacts), the process  700  loops back to the operations  710  and  720  where new sets of vital-sign readings and acceleration readings are received. In the illustrated exemplary process, previously received vital-sign readings are excluded from an alarm condition determination procedure of operation  770  to be described below, and, hence, a false alarm associated with the motion/position-related artifacts is prevented. 
     On the other hand, if the answer to the determination at the decision state  740  is NO (the patient motion/position not likely to produce artifacts), the process  700  proceeds to another decision state  750  in which it is determined whether the patent motion/position determined at the operation  730  is likely to cause significant changes to vital-sign readings to exceed an alarm threshold limit so as to warrant a modification to the alarm condition determination procedure This determination can involve the processor  360  analyzing the acceleration readings and classifying the patient motion/position to one of several categories of motions and positions. For example, by comparing the acceleration readings to certain known patterns stored in a memory of the surveillance server  60  or in a memory accessible by the server  60  or the patch  20 B, the processor  360  of the server  60  or the processor  202  of the patch  20 B can categorize the patient motion/position into one of: slow walking, normal walking, fast walking, running, twisting, and jumping. Some non-limiting examples of position categories include: prone, sitting, standing, sit-to-stand, stand-to-sit, prone-to-sit, or sit-to-prone). 
     In some embodiments, in conjunction with determining whether the patient motion/position is likely to cause changes in one or more vital-sign readings significant enough to cause an alarm, it is determined whether the significant changes are likely to have a clinical significance for the patient. If it is determined that the patient motion/position, while causing such significant changes, nevertheless is not likely to have any clinical significance for the patient (e.g., a 20-year old male patient who recently had a tonsillectomy walking vigorously down a hall), the answer to the determination of the decision state  740  is YES. The same or a similar physical activity can have a different outcome depending on patient-specific information such as age, sex, and medical condition of the patient. For example, if the patient is a 70-year old female patient who recently suffered a heart attack, and she is walking vigorously in the hallway, the surveillance server  60 , based on a rule database stored therein, for example, may determine that the activity is likely to cause significant changes in one or more vital-sign reading to activate an alarm, and such changes can have a clinical significance for the patient; and, accordingly, determine that the answer to the determination of the decision state  740  is NO. Therefore, in certain embodiments, the procedure or algorithm for the decision state  740  can take account of patient specific information such as age, sex, and medical conditions (present and past) of the patient  10 . 
     If the answer to the determination at the decision state  740  is NO (e.g., the patient motion/position not likely to cause significant changes, or changes, even if significant, are likely to have a clinical significance), the process  700  proceeds to operation  770  in which a standard (unmodified) alarm condition determination procedure is applied to the vital-sign readings to determine whether to send an alarm notification to the hospital system  100 . The alarm condition determination can involve comparing the vital-sign readings against one or more threshold limits. Such an alarm condition determination procedure based on an alarm threshold limit was described above with respect to  FIG. 5  and is not repeated here. 
     On the other hand, if the answer to the determination at the decision state  740  is YES (e.g., the patient motion/position likely to cause significant changes, and the significant changes are not likely to have a clinical significance), the process  700  makes a detour to operation  760  in which a modification is made to the alarm condition determination procedure, e.g., by increasing the alarm threshold limits for one or more vital signs, and then proceeds to operation  770  in which the modified alarm condition determination procedure is performed by the surveillance server  60  based on the increased alarm threshold limit. For example, the alarm condition determination procedure can include determining whether the vital-sign readings have stayed above the increased alarm threshold limit for a predetermined number of samples. 
     In certain embodiments, the amount of increase to the alarm threshold limit is fixed (e.g., 10%). In other embodiments, the amount of increase is linearly proportional to or is another type of a function based on a number of factors including, but not limited to: 1) level of patient&#39;s physical activity as determined by the acceleration readings, 2) time duration of the physical activity; 3) category for the patient motion/position (e.g., fast walking or lying on the side in a prone position); and 4) patient specific information such as age, sex, and medical condition (present and past). 
     The process  700  proceeds to decision state  780  in which it is determined whether the alarm condition determination of the operation  780  indicates an existence of an alarm condition. If the answer to the determination at the decision state  780  is NO (no alarm condition exists), the process  700  loops back to the operations  710  and  720  where new sets of vital-sign readings and acceleration readings are received from the monitor patch  20 B. On the other hand, if the answer to the determination at the decision state  780  is YES (an alarm condition exists), the process  700  proceeds to operation  790  in which an alarm notification is sent to the hospital system  100  and then to the operations  710  and  720  where new sets of vital-sign readings and acceleration readings are received from the monitor patch  20 B. 
     One skilled in the art would understand in view of the present disclosure that various systems and methods described above provide a number of important benefits to the vital sign monitoring system of the present disclosure including preventing or reducing occurrences of false alarms associated with motion and/or position of the patient to whom the monitor patch is attached. In addition, the systems and methods improve the quality and reliability of vital-sign readings actually used for the alarm condition determination. 
     The foregoing description is provided to enable any person skilled in the art to practice the various embodiments described herein. While the foregoing embodiments have been particularly described with reference to the various figures and embodiments, it should be understood that these are for illustration purposes only and should not be taken as limiting the scope of the claims. 
     The word “exemplary” is used herein to mean “serving as an example or illustration.” Any aspect or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. 
     A reference to an element in the singular is not intended to mean “one and only one” unless specifically stated, but rather “one or more.” The term “some” refers to one or more. Underlined and/or italicized headings and subheadings are used for convenience only, do not limit the invention, and are not referred to in connection with the interpretation of the description of the invention. All structural and functional equivalents to the elements of the various embodiments of the invention described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressed incorporated herein by reference and intended to be encompassed by the invention. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the above description.