Patent Publication Number: US-2007100247-A1

Title: Combined wrist blood pressure and ecg monitor

Description:
FIELD OF THE INVENTION  
      The present invention relates generally to diagnostic medical devices and, in particular to a device worn on a user&#39;s wrist which measures a number of biological parameters.  
     BACKGROUND TO THE INVENTION  
      Portable diagnostic medical devices are used for monitoring of biological signals of patients in order to detect disease.  
      Regular monitoring of blood pressure is recommended to patients with hypertension. Digital blood pressure monitors are accurate and convenient for home use. These monitors are easy to operate and they offer electronic data storage. Some of these monitors have a capability for the remote data transfer that is used for analysis of the dynamic of blood pressure-changes by the medical practitioner.  
      Patients with hypertension also have higher risk of heart diseases. A number of portable ECG recorders for ambulatory use are available for heart disease diagnostic. These devices are capable of electronic storage of user&#39;s electrocardiogram and of remote transmission of the stored signals for analysis by the medical practitioner. Portable ECG recorders are highly effective in detection of heart rhythm disorders.  
      It would be an advantage to monitor simultaneously both blood pressure and electrocardiogram in the patients with hypertension using single device.  
     OBJECT OF THE INVENTION  
      It is an object of present invention to provide a method and apparatus for simultaneous monitoring of blood pressure and electrocardiogram using an electronic device that incorporates blood pressure monitor and electrocardiograph  
      It is also an object of present invention to provide means for remote transmission of measured data in the above-mentioned device.  
     DISCLOSURE OF THE INVENTION  
      According to one aspect of the present invention there is disclosed a physiological monitor device having physiological detection means, signal transducer means, control and calculating means, display means, wherein said detection means includes an inflatable cuff means with pressure detection means to test for blood pressure and ECG electrode means to test for ECG, said electrodes being adapted to be secured at least to said cuff means.  
      Preferably, the cuff means is adapted to be secured to the wrist of a user, with at least some of the electrodes coming into contact with the skin of the user when so secured.  
      Preferably, the remainder of the electrodes are adapted to be either held by the user or attached to the user&#39;s body.  
      Preferably, the device monitors blood pressure and ECG measurements simultaneously. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      One embodiment of the invention will now be described with reference to the accompanying drawings in which:  
       FIG. 1  is a perspective view of a wrist blood pressure monitor,  
       FIG. 2  is a block diagram of the blood pressure monitor;  
       FIG. 3  is a block diagram of a typical single lead ECG recorder;  
       FIG. 4  is a block diagram of blood pressure monitor with ECG recorder function; and  
       FIG. 5  is perspective view of a wrist blood pressure monitor with ECG recorder functions of a preferred embodiment. 
    
    
     BEST MODE OF CARRYING OUT THE INVENTION  
      In the preferred embodiment of present invention a portable digital blood pressure monitor with ECG module is described.  
      Referring to  FIG. 1 , a portable blood pressure monitor is shown. Wrist blood pressure monitor  10  has a device enclosure  11  and inflatable cuff  12 . The cuff  12  is placed around the user&#39;s wrist and secured by two Velcro pads  13 . The wrist blood pressure monitor  10  is turned on by button  14 . A typical wrist blood pressure monitor is capable of automatic inflation of the cuff, termination of inflation when a predetermined cuff pressure level is reached and measurement of systolic and diastolic blood pressure and heart rate. Measured values are displayed on an LCD display  15 .  
      Referring again to  FIG. 1 , a mini-speaker output  16  is shown. The speaker is used to produce audio tones when the user&#39;s heartbeat is detected or to generate warning sounds when measurement errors occur.  
      Referring again to  FIG. 1 , a communication connector  17  is shown. This connector  17  is used for connection to a PC (not illustrated) for reading blood pressure data stored in the device  10 .  
      A functional block-diagram of a digital blood pressure monitor (BPM)  20  is shown in  FIG. 2 . The core of the BPM is a CPU unit  21 . The CPU  21  of the BPM  20  controls all peripherals of the device  20  and performs calculations necessary for blood pressure determination.  
      A pneumatic circuit  22  of the BPM  20  is shown in  FIG. 2 . The pneumatic circuit  22  is formed by a cuff  23 , an air pump  24 , an exhaust valve  25  and a pressure transducer  26 . Peripherals of the CPU  21  are shown in  FIG. 2  and include on button,  27 , speaker  28 , LCD display  29 , real time clock  30 , memory  31  and serial interface  32 .  
      The BPM  20  is operated such that when button  27  is depressed by the user, the CPU  21  measures cuff air pressure from the pressure transducer  26  and calibrates ‘zero’ pressure. The CPU  21  then turns on normally opened valve  25  and the air pump  24 . The air pump  24  creates pressure in the cuff  23 . The CPU  21  via the pressure transducer  26  continually monitors the cuff pressure. When the cuff pressure reaches a predetermined level, the CPU  21  stops the pump  24  and starts to measure blood pressure. During measurement the CPU  21  detects heart beats and generates short audio beeps through a speaker  28 . When blood pressure is measured, the CPU  21  turns off valve  25  and displays the measured values on a LCD display  29 . The CPU  21  reads current time from real time clock  30  and stores measured blood pressure values, heart rate and date and time of the measurement into a memory  31 . Once stored in the memory  31  data can be transmitted to the PC via serial interface  32  or by generating modulated audio tones via the speaker  28 ,  
      Such operation of digital blood meters is well known within the art.  
      Referring to  FIG. 3 , a functional block diagram of typical single lead ECG recorder  40  is shown. A CPU  41  controls peripherals of the ECG recorder  40 . The peripherals include ECG amplifier  42 , real time clock  43 , LCD display  44 , data memory  45 , serial interface  46 , speaker  47 , push button ‘Record’  48  and push button ‘Transmit’  49 .  
      The CPU  41  of ECG recorder  40  receives ECG signals via non-inverting input  50 , inverting input  51  and current return path  52  through the ECG amplifier  42 . The ECG amplifier  42  amplifies the ECG signal to a level acceptable by the requirements of dynamic range of the ECG recorder  40 .  
      The non-inverting input  50 , inverting input  51  and current return path  52  are electrically connected to three external ECG electrodes (not illustrated). The ECG electrodes can be used in form of adhesive press-stud electrodes connected to the three-wire cable or in form of conductive pads located on the enclosure of the ECG recorder. A combination of cable electrodes and conductive electrodes can also be used. The ECG electrodes are applied to the skin of the patient when the ECG signal is acquired.  
      In its operation, when button  48  ‘Record’ is depressed, the CPU  41  reads current time from the real time clock  43  and starts to acquire signal from the ECG amplifier  53  and record it into data memory  45 . Date and time of the beginning of the recording is stored in the particular location of the data memory  45 . The CPU  41  displays the ECG signal on the LCD display  44 . The ECG recorder  40  typically acquires and records data from several seconds to several hours. When recording is finished, the CPU  41  issues an ‘End of recording’ audio tone via the speaker  47 . When button  49  ‘Transmit’ is depressed, the CPU  41  transmits ECG data stored in the memory  45  via the serial interface  46  and/or using modulated audio tones via speaker  47 .  
      It can be seen that functional block-diagrams of the blood pressure monitor and ECG recorder are pretty similar. Both of them have the same peripherals except for the source of the signal and two pneumatic components. It would be an advantage to share common for both devices peripherals in order to minimize costs and combine their functionality.  
      A functional block-diagram of digital blood pressure monitor with ECG-recorder (BPM-ECG)  60  is shown in  FIG. 4 .  
      Referring again to  FIG. 2 ,  FIG. 3  and  FIG. 4 , all three functional block diagrams include CPU, real time clock, LCD display, data memory, serial interface, speaker and button(s).  
      Referring again to  FIG. 4 , functional block-diagram of BPM-ECG  60  includes ECG amplifier  61  and pneumatic circuit  62 . The pneumatic circuit  62  includes an inflatable cuff  63 , an air pump  64 , a valve  65  and a pressure transducer  66 . The BPM-ECG  60  further includes a CPU  67  which is connected to the output of the ECG amplifier  61  which is connected to via non-inverting input  69 , inverting input  70  and current return path  71 ; and to the components of pneumatic circuit  62 .  
      The BPM-ECG  60  further includes peripherals which include real time clock  73 , LCD display  74 , data memory  75 , serial interface  76 , speaker  77 , push button ‘Record’  78  and push button ‘Transmit’  79 .  
      Referring again to  FIG. 4 , when button  78  ‘Record’ is depressed, the CPU  67  calibrates its pressure transducer  66 , turns on valve  65  and air pump  64 . At the same time the CPU  67  receives ECG signals from electrodes associated with the non-inverting input  69 , the inverting input  70  and the current return path  71  via the amplifier  61 . The CPU  67  records ECG signal into the memory  75  and displays it on the LCD  74 .  
      When measurement of blood pressure is finished, the CPU  67  stops recording and display of the ECG signal and displays measured blood pressure values. Then the CPU  67  reads real time clock  73  and stores date, time and measured values in the data memory  75 .  
      Referring again to  FIG. 4 , when button  79  ‘Transmit’ is depressed, the CPU  67  reads stored ECG and blood pressure data from its memory  75  via serial interface  76  and/or using modulated audio tones via speaker  77 .  
      Referring to  FIG. 5 , a drawing of the preferred embodiment BPM-ECG  80  is shown. The BPM-ECG  80  includes enclosure  81 , inflatable cuff  82  with Velcro pads  83 . On the inner surface of the cuff  83 , two conductive ECG electrodes  84  (non-inverting input) and  85  (current return path) are positioned. The third, inverting input of ECG amplifier is connected to an external pad electrode  86  and to a one-way connector  87 . When the BPM-ECG  80  is placed around the user&#39;s wrist, electrodes  84  and  85  come in close contact with the skin. The external electrode  85  is exposed and the user can touch it with the finger to provide connection to the inverting input of the ECG amplifier. Alternatively, a single wire lead with adhesive press-stud electrode can be placed to the chest of the user and connected via connector  87  to the inverting input of ECG amplifier. An on button  88 , mini output speaker  89 , connector  90 , display  91  and record button  92  are used in the aforementioned manner.  
      Throughout the specification, the word “comprise” and its derivatives are intended to have an inclusive rather than an exclusive meaning unless the context requires otherwise.  
      The foregoing describes only some embodiments of the present invention, and modifications obvious to those skilled in the art can be made thereto without departing from the scope of the present invention.