Patent Publication Number: US-2020297225-A1

Title: Vital sign measurement device

Description:
TECHNICAL FIELD 
     The present invention relates to a vital sign measurement device for simultaneously measuring vital signs including a blood pressure and an electrocardiogram of a subject. 
     BACKGROUND ART 
     Conventionally, in medical setting, a device that measures various vital signs of a subject such as a blood pressure, an electrocardiogram, a heart rate, a body temperature, and a blood oxygen saturation level has been used. These vital signs are very important in the medical setting, but generally, these vital signs are separately measured by type. 
     On the other hand, Patent Document 1 discloses a remote diagnostic device configured to simultaneously measure vital signs including the blood pressure and the electrocardiogram. This device is configured such that an electrocardiogram measurement electrode and a blood pressure and heart rate measurement device are mounted on a glove member adaptable to be worn on a person&#39;s hand, and such biosignals can be detected by applying this glove member to a chest of a subject.
     Patent Document 1: Pamphlet of WO/1999/060919   

     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     However, in the glove-type diagnostic device disclosed in Patent Document 1, for the electrocardiogram measurement, a distance between the electrodes can be separated only by a size of a palm of the hand at maximum, thus having a problem that an electrocardiogram waveform cannot be accurately measured since an electric potential difference between the electrodes is small. The electrocardiogram measurement electrode has to contact a skin of the subject. However, in the device in Patent Document 1 designed on the premise of applying the glove member to the chest, it is necessary to expose the chest of the subject in use. Thus, there is a concern that a usable environment is restricted. 
     Therefore, an object of the present invention is to easily and accurately acquire an electrocardiogram waveform in a device that simultaneously measures vital signs such as a blood pressure and an electrocardiogram. 
     Solutions to the Problems 
     The inventor of the present invention earnestly examined a solution for the above-described problem of the conventional invention, and as a result, acquired an knowledge that a blood pressure measurement cuff and a biosignal sensor for measuring other vital signs are provided, at least one of electrocardiogram measurement electrodes is mounted on the cuff, and other electrodes are mounted on the biosignal sensor, thus ensuring simultaneous measurement of at least three kinds of vital signs including the blood pressure and the electrocardiogram and easily keeping a distance between the electrodes to ensure accurate measurement of an electrocardiogram waveform. Then, the inventor thought that the problem of the prior art can be solved based on the above-described knowledge and completed the present invention. Specifically, the present invention has the following configuration. 
     The present invention relates to a vital sign measurement device. The vital sign measurement device according to the present invention includes a blood pressure measurement cuff, one or a plurality of biosignal sensors, a plurality of electrocardiogram measurement electrodes, and a device body coupled to them. The device body measures a blood pressure of a subject by increasing and decreasing a cuff pressure in the cuff. The device body measures a vital sign other than the blood pressure or an electrocardiogram of the subject based on a biosignal detected by the biosignal sensor. “The vital sign other than the blood pressure or the electrocardiogram” includes various vital signs such as a pulse, a blood oxygen saturation level, a heartbeat, a body temperature, a heart sound, a brain wave, a respiratory sound, and a respiration rate. Thus, as the biosignal sensor, a known one for measuring these vital signs can be appropriately employed. The device body further measures the electrocardiogram of the subject based on physical electrical potentials detected by the plurality of electrodes. At least one of the plurality of electrodes is provided to the cuff (a part contacting the skin of the subject), and at least another of the plurality of electrodes is provided to the biosignal sensor (a part contacting the skin of the subject). 
     As the above-described configuration, providing the respective electrocardiogram measurement electrodes to the blood pressure measurement cuff and the biosignal sensor for measuring other vital signs facilitates sufficiently separated distance between the electrodes, thus ensuring accurate measurement of the electrocardiogram. The cuff is generally wound around one arm of the subject. For example, while the cuff is mounted on one arm, the biosignal sensor can be operated by another arm, thus facilitating use of the measurement device by the subject himself/herself. What is called, a I Induction can be detected by detecting the physical electrical potentials of the arm on which the cuff is mounted and the arm gripping the biosignal sensor with the electrodes, thus having a sufficient electric potential difference to be effective for detection of an arrhythmia. Further, simultaneously with the electrocardiogram, the blood pressure and the other vital signs can be measured. 
     In the present invention, the biosignal sensor preferably includes a pulse oximeter probe. The probe irradiates a biological tissue having a bloodstream of the subject with a light to detect optical information of a transmitted light or a reflected light. In this case, the device body measures at least any one of a blood oxygen saturation level and a pulse of the subject based on the optical information detected by the probe. With such a configuration, the blood oxygen saturation level and the pulse can be simultaneously measured in addition to the blood pressure and the electrocardiogram. 
     In the present invention, the biosignal sensor may further include a thermometer. With it, the body temperature of the subject can be simultaneously measured in addition to the blood pressure, the electrocardiogram, the blood oxygen saturation level, and the pulse. 
     In the present invention, the biosignal sensor preferably further includes a digital stethoscope chest piece. The chest piece includes a microphone that converts a heart sound of the subject into an electrical signal. With such a configuration, the heart sound and the respiratory sound of the subject can be simultaneously measured in addition to the blood pressure, the electrocardiogram, the blood oxygen saturation level, and the pulse. 
     In the present invention, it is preferable that any one of the plurality of electrodes is provided to a part contacting the skin of the subject in the probe, and another of the plurality of electrodes is provided to a part contacting the skin of the subject in the chest piece. With such a configuration, a first electrode provided to the cuff, a second electrode provided to the probe, and a third electrode provided to the chest piece ensure measurement of the physical electrical potentials of the subject at three portions, thus improving an accuracy of the electrocardiogram. For example, in addition to a bipolar lead between the first electrode and the second electrode, bipolar leads between the first electrode and the third electrode and between the second electrode and the third electrode can be measured. 
     In the present invention, the probe and the chest piece to which the respective electrodes are provided may be removably combined. For example, by mounting the chest piece on the probe having a type used by inserting a hand finger into it, the subject can acquire the heart sound and the like by pressing this finger to the chest while fitting the finger to the probe, thus facilitating operation of each piece of equipment. On the other hand, for example, when the auscultation of the heart sound and the like is not necessary, the chest piece can be removed. Alternatively, when the subject cannot lift the chest piece to his/her chest because of a physical reason such as paralysis and contracture, while the pulse oximeter is mounted on the hand finger of the subject, a helper can press the chest piece to the chest of the subject. Thus, the probe and the chest piece can be used by attaching and removing them corresponding to the usage situation. 
     In the present invention, the device body preferably extracts the pulse wave of the subject from the electrocardiogram and, in a process of decreasing the cuff pressure in the cuff after increasing it, measures a maximum blood pressure and a minimum blood pressure of the subject at a timing corresponding to this pulse wave. This can improve an accuracy of the blood pressure measurement using an electrocardiogram waveform. That is, an automated sphygmomanometer generally measures the maximum blood pressure and the minimum blood pressure of the subject by employing an oscillometric method. However, when the subject is suffering from the low blood pressure or the arrhythmia, the pulse wave is sometimes hard to be sensed to make the blood pressure immeasurable. In this respect, an accuracy of the automated sphygmomanometer can be enhanced by accurately acquiring the timing of the pulse wave of the subject from the electrocardiogram and acquiring the maximum blood pressure and the minimum blood pressure at the timing corresponding to pulsation. 
     In the present invention, the device body may extract a time slot of both or any one of a systole and a diastole of a heart of the subject from the electrocardiogram and determine whether there is a heart murmur in the heart sound in the time slot (the systole and/or the diastole) extracted from a heart sound signal acquired by the microphone. Such a configuration can automatically acquire the heart murmur of roughly the systole and the diastole of the heart generated in a disease such as an aortic valve stenosis and the like or an aortic valve insufficiency. Determination of the systole or the diastole with reference to electrocardiogram data ensures an accurate and automatic determination of the heart murmur. 
     In the present invention, the device body discriminates the time slots of the systole and the diastole of the heart of the subject from the electrocardiogram and acquires a difference (that is, a “pulse pressure”) in the blood pressures of the subject in the systole and the diastole. The “pulse pressure” means a difference between a systolic blood pressure and a diastolic blood pressure. When the heart murmur is recognized in the systole, the subject is strongly suspected of suffering from the aortic valve stenosis. This disease has a trend that the heart murmur in the systole increases as a symptom gets worse, but the heart murmur in the systole rather becomes weak as the symptom further becomes severe. This is because, in the severe aortic valve stenosis, a wall of a left ventricle of the heart becomes thick and contraction becomes weak, thus reducing an outflow of blood. Thus, even the heart murmur in the systole is measured, the end-stage aortic valve stenosis may be overlooked. Accordingly, as the above-described configuration, simultaneously measuring the pulse pressure in addition to the heart murmur in the systole can examine the severe aortic valve stenosis from the aspect of the heart murmur and the pulse pressure, thus enhancing an accuracy in diagnosis of disease. Specifically, even when the heart murmur in the systole is lower than a constant threshold, insofar as the pulse pressure is equal to or less than a threshold, it may automatically diagnose that the subject is suspected of suffering from the aortic valve stenosis. Further, when the heart murmur is recognized in the diastole, the subject is strongly suspected of suffering from the aortic valve insufficiency. However, this aortic valve insufficiency, in a severe case, also has a trend that the heart murmur in the diastole becomes weak. Accordingly, also in this case, simultaneously measuring the pulse pressure in addition to the heart murmur in the diastole can examine the severe aortic valve insufficiency from the aspect of the heart murmur and the pulse pressure. Specifically, even when the heart murmur in the systole is lower than a constant threshold, in a case where the pulse pressure exceeds a threshold, it may automatically diagnose that the subject is suspected of suffering from the aortic valve insufficiency. 
     Advantageous Effects of the Invention 
     With the present invention, in the device for simultaneously measuring the vital signs such as the blood pressure and the electrocardiogram, the electrocardiogram waveform can be easily and accurately acquired. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram illustrating a use state of a vital sign measurement device according to a first embodiment of the present invention. 
         FIG. 2  is a block diagram illustrating an exemplary configuration of the vital sign measurement device. 
         FIG. 3  schematically illustrates an exemplary automatic detection of heart murmur. 
         FIG. 4  illustrates an exemplary automatic diagnosis flow of an aortic valve stenosis. 
         FIG. 5  illustrates an exemplary automatic diagnosis flow of an aortic valve insufficiency. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The following describes an embodiment of the present invention using the drawings. The present invention is not limited to the embodiment described below and includes ones appropriately changed in an obvious range by those skilled in the art from the following embodiment. 
       FIG. 1  schematically illustrates a use state of a vital sign measurement device  100  according to a first embodiment.  FIG. 2  illustrates an exemplary configuration of the vital sign measurement device  100  illustrated in  FIG. 1 . As illustrated in  FIG. 1  and  FIG. 2 , the vital sign measurement device  100  includes a device body  10 , a blood pressure measurement cuff  20 , a pulse oximeter probe  30 , and a digital stethoscope chest piece  40 . Further, one or a plurality of electrocardiogram measurement electrodes  51 ,  52 ,  53 , and  54  are mounted on the cuff  20 , the probe  30 , and the chest piece  40 . Thus, the vital sign measurement device  100  according to the embodiment is configured to simultaneously measure vital signs such as a blood pressure, a blood oxygen saturation level, a pulse, a heart sound, a respiratory sound, and an electrocardiogram waveform of a subject. 
     As illustrated in  FIG. 1 , the device body  10  includes a central processing unit (CPU)  11 , a storage unit  12 , a display unit  13 , and an operation unit  14  as underlying function blocks. The CPU  11  controls the whole vital sign measurement device  100  by reading a program stored in the storage unit  12  and controlling other components and executing predetermined computing in accordance with this program. The storage unit  12  has a storage function achieved by a non-volatile memory such as an HDD and an SDD. The storage unit  12  may have a function as a memory for writing or reading, for example, an interim progress of computation processing by the CPU  11 . The memory function of the storage unit  12  is achieved by a volatile memory such as a RAM and a DRAM. The display unit  13  is a display device such as a liquid crystal display and an organic EL display. The operation unit  14 , which is configured from input devices such as a computer mouse, a keyboard, a touch panel, and a microphone, accepts operation information by humans. The display unit  14  may configure a touch panel display integrally with the operation unit  15 . 
     In the measurement device  100  of the present invention, a sphygmomanometer is configured from the cuff  20  having an air bag  21 , and the CPU  11 , a pressure sensor  22 , an oscillation circuit  23 , a pump  24 , a pump driving circuit  25 , a pressure release valve  26 , a valve driving circuit  27 , and an air hose  28  included in the device body  10 . 
     The cuff  20  is a strip-shaped member used by being wound around a blood pressure measurement part, for example, an upper arm of the subject and internally includes the air bag  21 . The air bag  21  communicates with the pressure sensor  22 , the pump  24 , and the pressure release valve  26  via the air hose  28 . The air bag  21  expands in a way that air is sent into its internal space from the pump  24  and contracts in a way that the air in the internal space is released through the pressure release valve  26 . The air bag  21  of the cuff  20  internally has an air pressure (a cuff pressure) detected by the pressure sensor  22 . 
     The pressure sensor  22 , which is, for example, a pressure-electricity converter using a semiconductor pressure sensor, is provided to the air hose  28 . The pressure sensor  22 , which converts the air pressure (the cuff pressure) of the air bag  21  of the cuff  20  into an electrical signal, has a capacitance value that varies depending on the cuff pressure. The oscillation circuit  23  outputs a signal (a pressure signal) having an oscillation frequency corresponding to the capacitance value of the pressure sensor  22  to the CPU  11 . The CPU  11  generates cuff pressure data based on the signal acquired from the oscillation circuit  23 . The cuff pressure data shows a waveform of the cuff pressure. For example, a pulse wave component as a signal component representing a pulse wave of the subject is superimposed on the waveform of the cuff pressure at the time of the blood pressure measurement. The CPU  100  measures a minimum blood pressure and a maximum blood pressure of the subject based on this cuff pressure data. 
     The pump  24  increases the cuff pressure by supplying the air bag  21  of the cuff  20  with the air through the air hose  28 . The pump driving circuit  25 , which controls driving of the pump  24  by outputting a drive signal to the pump  24  in accordance with a control signal from the CPU  11 , starts and stops air supply from the pump  24  to the cuff  20 . 
     The pressure release valve  26 , which is, for example, an electromagnetic valve, is provided to the air hose  28 . The pressure release valve  26  blocks air release from the air bag  21  of the cuff  20  while the valve is closed and releases the air in the air bag  21  of the cuff  20  through the air hose  28  while the valve is open. The valve driving circuit  27 , which controls driving of the pressure release valve  26  in accordance with the control signal from the CPU  11 , adjusts a degree of opening of the pressure release valve  26 . 
     The CPU  11  may generate the control signal with respect to the pump driving circuit  25  and the valve driving circuit  27  and process the cuff pressure data acquired by the pressure sensor  22  like measuring the blood pressure by a common oscillometric method. Specifically, the CPU  11  sends the air into the cuff  20 , presses a blood vessel of the subject by increasing the cuff pressure, and blocks a flow of blood. Thereafter, as the CPU  11  gradually decreases the cuff pressure, the pressure of the blood exceeds the pressure of the cuff, and from this time point, the blood starts intermittently flowing in accordance with a heartbeat (a pulse). In the oscillometric method, in a process of decreasing the pressure of the cuff after increasing it, a vibration of a blood vessel wall that is synchronous with the heartbeat (the pulse) by the timing is regarded as a variation of the cuff pressure (a pressure pulse wave). The CPU  11  measures a blood pressure value of the subject by measuring an amount of variation of the cuff pressure at the timing corresponding to the heartbeat. Generally, a cuff pressure when the pulse wave has rapidly increased is defined as “the maximum blood pressure,” and a cuff pressure when the pulse wave has rapidly decreased is defined as “the minimum blood pressure.” 
     In the measurement device  100  of the present invention, a pulse oximeter is configured from the probe  30  including a light-emitting element  31  and a light-receiving element  32 , and the CPU  11 , a light-emitting circuit  33 , and a light-receiving circuit  34  included in the device body  10 . The pulse oximeter non-invasively measures a blood oxygen saturation level SpO 2  by irradiating a biological tissue having a bloodstream such as a fingertip or an ear with a light from the probe to detect the light transmitted through or reflected on the biological tissue, using a principle that a light absorption property is different between HbO 2  (hemoglobin containing oxygen) and Hb (hemoglobin without the oxygen) in blood hemoglobin depending on an optical wavelength. The pulse oximeter is configured to simultaneously measure the pulse of the subject. 
     The probe  30  includes the light-emitting element  31  and the light-receiving element  32 , and these elements  31  and  32  are provided to, for example, a fingerstall mounted on the fingertip or the like of the subject. An example of the light-emitting element  31  is a light-emitting diode. At least two kinds of light-emitting elements  31 , for example, one that emits a red light and one that generates an infrared light, are provided. The two kinds of light-emitting elements  31  are alternately driven to light with a predetermined period by the light-emitting circuit  33  in the device body  10 . The light-receiving element  32  is arranged at a position opposed to the light-emitting element  31  in the probe  30 . An example of the light-receiving element  32  is a silicon photodiode. The light-receiving element  32  photoelectrically converts the light transmitted through the biological tissue and inputs a light signal to the light-receiving circuit  34  in the device body  10 . The light-receiving circuit  34  amplifies the light signal acquired from the light-receiving element  32  to input it to the CPU  11 . 
     The CPU  11  acquires a ratio of change rates of the red light and the infrared light based on an AC component where the red light has varied, an AC component where the infrared light has varied, a DC component where the red light does not vary, and a DC component where the infrared light does not vary. The CPU  11  reads a value of the blood oxygen saturation level (SpO 2  value) preliminarily stored in the storage unit  12  in accordance with characteristics such as a wavelength and a half-value width of the light-emitting element  31  with being associated with this ratio. Thus, the blood oxygen saturation level of the subject is measured. The CPU  11  can also measure a pulse rate per unit time of the subject based on information such as a strength variation of the light signal. 
     In the measurement device  100  of the present invention, a digital stethoscope is configured from the chest piece  40  including a microphone  41 , and the CPU  11  and an acoustic processing circuit  42  included in the device body  10 . 
     The chest piece  40  has a surface directly contacting the measurement part (mainly, a chest) of the subject, thus having a structure that collects the heart sound and the respiratory sound. The chest piece  40  incorporates the microphone  41 . The microphone  41  converts the sound (vibration) collected at the chest piece  40  into an acoustic signal (a vibration signal) as the electrical signal to output it to the acoustic processing circuit  42  in the device body  10 . The acoustic processing circuit  42 , after amplifying the acoustic signal, converts it from an analog signal into a digital signal and perform a filtering process for correcting an acoustic characteristic (a frequency characteristic and a phase characteristic) on the digitized acoustic signal, thus output it to the CPU  11 . The CPU  11  performs a process for determining whether the heart sound of the subject contains noise or not, for example, based on the acoustic signal acquired from the acoustic processing circuit  42 . 
     In the measurement device  100  of the present invention, an electrocardiographic monitor is configured from the plurality of electrodes  51 ,  52 ,  53 , and  54  provided to the respective cuff  20 , probe  30 , and chest piece  40 , and the CPU  11  and an electrocardiogram processing circuit  55  included in the device body  10 . The electrocardiographic monitor measures an electrocardiogram where a flow of electricity in a heart of the subject is recorded. 
     The plurality of electrodes include, for example, a first electrocardiograph electrode  51 , an indifferent electrode  52 , a second electrocardiograph electrode  53 , and a third electrocardiograph electrode  54 . In the example illustrated in the drawing, the first electrocardiograph electrode  51  and the indifferent electrode  52  are provided to a part contacting a skin of the subject in the cuff  20 . The second electrocardiograph electrode  53  is provided to a part contacting the skin of the subject in the probe  30 . Further, the third electrode  40  is provided to a part contacting the skin of the subject in the chest piece  40 . Insofar as, at least, one electrocardiograph electrode  51  is provided to the cuff  20  and another one of the electrocardiograph electrodes  53  and  54  is provided to another biosignal sensor (the probe  30  or the chest piece  40 ), the electrocardiogram can be measured. For example, insofar as the first electrocardiograph electrode  51  and the indifferent electrode  52  are provided to the cuff  20  and the second electrocardiograph electrode  53  is provided to the probe  30 , the third electrocardiograph electrode  54  of the chest piece  40  can be omitted. 
     The first to third electrocardiograph electrodes  51 ,  53 , and  54  contact the measurement parts of a human body, thus functioning as electrodes for detecting physical electrical potentials of the measurement parts. Electric potential differences in the measurement parts can be derived based on electrocardiographic potentials acquired from the plurality of electrocardiograph electrodes  51 ,  53 , and  54 . The indifferent electrode  52  functions as an electrode for removing external noise induced in phase with the plurality of electrocardiograph electrodes  51 ,  53 , and  54 . The respective electrodes  51  to  54  are coupled to the electrocardiogram processing circuit  55  in the device body  10 . Potential variations (the physical electrical potentials) derived from the respective electrocardiograph electrodes  51 ,  53 , and  54  and the indifferent electrode  52  are input to the electrocardiogram processing circuit  55 . The electrocardiogram processing circuit  55  differentially amplifies the physical electrical potentials derived by the respective electrocardiograph electrodes  51 ,  53 , and  54  and removes the external noise with the derived potential from the indifferent electrode  52 , thus creating an amplified electrocardiogram signal (electrocardiogram waveform). A method for creating the electrocardiogram signal may be a bipolar induction method to create the electrocardiogram using two-point electrodes as one set or a monopolar induction method to create the electrocardiogram between electrodes using the indifferent electrode as an origination, using three-point electrodes including the indifferent electrode. This amplified electrocardiogram signal is input to the CPU  11 . The CPU  11  performs an analog-digital conversion on the electrocardiogram signal received from the electrocardiogram processing circuit  55 , and, after performing data compression and other signal processing on the electrocardiogram signal as necessary, records the electrocardiogram signal after processing in the storage unit  12 . 
     In the present invention, at least one electrocardiograph electrode  51  is provided to the cuff  20 , and another electrocardiograph electrode making a pair with the electrocardiograph electrode  51  is provided to another biosignal sensor. For example, when the cuff  20  is wound around one arm of the subject and the probe  30  is mounted on the fingertip of another arm of the subject, the electrocardiogram signal can be created based on the electric potential difference between the first electrocardiograph electrode  51  provided to the cuff  20  and the second electrocardiograph electrode  53  provided to the probe  30 . Such a configuration can improve an accuracy of the electrocardiogram signal since a distance between the first electrocardiograph electrode  51  and the second electrocardiograph electrode  53  can be sufficiently taken. What is called, a I induction can be seen based on the electric potential difference between the electrocardiograph electrodes mounted on both arms, thus being effective also in a detection of an arrhythmia. 
     In the present invention, a heart murmur may be automatically detected based on the electrocardiogram signal measured by the electrocardiographic monitor and the acoustic signal of the heart sound measured by the digital stethoscope.  FIG. 3  illustrates this mechanism. The CPU  11  accepts the electrocardiogram signal created based on physical electrical potential differences detected by the respective electrodes  51  to  54 .  FIG. 3A  illustrates an exemplary electrocardiogram acquired based on the electrodes  51  to  54 . The electrocardiogram includes a P wave, a Q wave, an R wave, an S wave, and a T wave. A period from a peak of the R wave to an end of the T wave is a systole of the heart, and a period other than it is a diastole of the heart. The CPU  11  accepts the acoustic signal sent from the microphone  41 .  FIG. 3B  illustrates an exemplary sound around the heart detected by the microphone  41 . The heart sound is a sound generated in association with the pulse of the heart, and the first heart sound, the second heart sound, the third heart sound, and the fourth heart sound are generated. Among these sounds, a sound generated immediately after the start of the systole of the heart is the first heart sound, and a sound generated at a border between the systole and the diastole is the second heart sound. The heart murmur is generated in association with the pulse of the heart but is a sound that is not generated in a normal heart. The respiratory sound and the like are normal sounds generated by an activity in the body such as respiration separately from the heart. The microphone  41  converts a sound where the heart sound, the heart murmur, the respiratory sound, and the like overlap into the electrical signal. Thus, the acoustic signal accepted by the CPU  11  contains a sound where sounds around the heart multiply overlap. 
     The CPU  11  extracts the systole of the heart based on the electrocardiogram signals acquired from the respective electrodes  51  to  54 . Specifically, the R wave and the T wave are extracted from the electrocardiogram illustrated in  FIG. 3A  to define the period from the peak of the R wave to the end of the T wave as the systole. However, the second heart sound is generated at the end of the T wave. Thus, here, it is good that a time slightly before the end of the T wave is defined as an end time of the systole so as not to contain the second heart sound. Then, the CPU  11  determines whether there is the heart murmur in the extracted systole. For example, the CPU  11  detects whether there is a sound having an amplitude that exceeds a predetermined threshold between 0.3 seconds after a start of the systole and the end of the systole. The threshold can be set as necessary, for example, by acquiring it from the amplitude of the first heart sound or using an absolute value acquired in an experiment or the like. The reason why the determination is performed from 0.3 seconds after the start of the systole is to eliminate a period until the first heart sound as a large sound always existing at the start of the systole sufficiently decreases. This period is influenced by the pulse rate and the like. Thus, it is not limited to 0.3 seconds, can be appropriately changed, and may be set to vary corresponding to the pulse rate. Further, when there is a sound exceeding the threshold, the CPU  11  records its generation timing within the systole. Then, the CPU  11  determines that there is the heart murmur when, after the detection in consecutive multiple times (for example, ten times) of systoles is performed, there are the sounds exceeding the threshold at an identical timing in all the times. The reason why the determination is performed based on the multiple times of systoles is to eliminate the influence of the noise such as the respiratory sound. From the timing of respiration, for example, around ten times of measurements can eliminate the influence of the respiratory sound. This number of times is not limited to ten times and may be appropriately changed. A criterion for determination that there are the sounds exceeding the threshold in all of the ten times of systoles is also an example. A condition for determination can be also appropriately changed such as determining that there is the heart murmur even when the sounds exceed the threshold less than ten times. 
     In the present invention, using the electrocardiogram signal measured by the electrocardiographic monitor, an accuracy of the blood pressure measurement by the sphygmomanometer can be enhanced. The CPU  11  accepts the electrocardiogram signal created based on the physical electrical potential differences detected by the respective electrodes  51  to  54 . Then, the pulse wave of the subject is extracted from this electrocardiogram signal. Specifically, the systole of the heart (the period from the peak of the R wave to the end of the T wave is the systole of the heart: see  FIG. 3A ) is extracted. The CPU  11 , after increasing the cuff pressure in the cuff by controlling the pump  24 , decreases the pressure of the pressure release valve  26 , and measures the maximum blood pressure and the minimum blood pressure of the subject in a process from the pressurization to the depressurization. Here, when a sign of the arrhythmia is seen in the subject, the blood pressure may become highest at a timing other than the systole of the heart. Alternatively, when a sign of a low blood pressure is seen in the subject, the blood pressure may become lowest at a timing other than the systole of the heart. These maximum blood pressure and minimum blood pressure at the timing other than the systole of the heart cannot be said to accurately indicate the blood pressure value of the subject. Thus, the CPU  11  ignores (cancels) the maximum blood pressure and the minimum blood pressure at the timing other than the systole of the heart and measures the maximum blood pressure and the minimum blood pressure detected within the period of the systole of the heart. Thus, it is possible to enhance an accuracy of the automated sphygmomanometer by accurately acquiring the timing of the pulse wave of the subject from the electrocardiogram and acquiring the maximum blood pressure and the minimum blood pressure at the timing corresponding to pulsation. 
     When the probe  30  and the chest piece  40  are employed as the biosignal sensor for measuring the vital signs, these probe  30  and chest piece  40  preferably have a mechanism removably combined. The probe  30  and the chest piece  40  may be ones combinable with a physical structure such as fitting to one another or may be ones combinable with a magnetic force by mounting permanent magnets on both. This facilitates holding of the probe  30  and the chest piece  40  in one hand, for example, as illustrated in  FIG. 1 . In accordance with a usage situation, the probe  30  and the chest piece  40  can be separately used. 
     In the embodiment illustrated in  FIG. 1  and  FIG. 2 , the auscultation chest piece  40  is employed, but instead of it or together with it, a thermometer (not illustrated) for measuring a body temperature of the subject may be employed. In this case, one or more electrocardiogram measurement electrodes are provided to a part contacting the skin of the subject in the thermometer. 
       FIG. 4  illustrates an exemplary automatic diagnosis flow for an aortic valve stenosis. The CPU of the device body  10  discriminates time slots of the systole and the diastole of the heart of the subject from the electrocardiogram and acquires a difference (that is, “the pulse pressure”) in the blood pressures of the subject in the systole and the diastole. As described above, when the heart murmur is recognized in the systole, the subject is strongly suspected of suffering from the aortic valve stenosis. This disease has a trend that the heart murmur in the systole increase as the symptom gets worse, but the heart murmur in the systole rather becomes weak as the symptom further becomes severe. On the other hand, a patient suffering from an end-stage aortic valve stenosis has a trend that the pulse pressure decreases. Accordingly, simultaneously measuring the pulse pressure in addition to the heart murmur in the systole ensures a more certain diagnosis even in a case of the severe aortic valve stenosis. 
     That is, as illustrated in  FIG. 4 , when the systolic murmur is equal to or less than a constant threshold and the pulse pressure is equal to or more than a constant threshold, it is diagnosed that the subject is normal. On the other hand, when the systolic murmur exceeds the constant threshold, it is diagnosed that the subject is suspected of suffering from the aortic valve stenosis. Even when the systolic murmur is equal to or less than the constant threshold, in a case where the pulse pressure is less than the constant threshold, it is diagnosed that the subject is suspected of suffering from the aortic valve stenosis. The patient of the aortic valve stenosis has a trend that the pulse pressure decreases, and in an extreme case, the blood pressure is 120 mmHg (the systole)/110 mmHg (the diastole), thus having a significant small difference (that is, the pulse pressure) between a systolic blood pressure and a diastolic blood pressure. In this case, even when the systolic murmur is equal to or less than the threshold, it can be diagnosed that the subject is suspected of suffering the aortic valve stenosis. The threshold of the systolic murmur and the threshold of the pulse pressure may be appropriately adjusted. 
       FIG. 5  illustrates an exemplary automatic diagnosis flow for an aortic valve insufficiency. The CPU of the device body  10  discriminates time slots of the systole and the diastole of the subject from the electrocardiogram and acquires a difference (that is, “the pulse pressure”) in the blood pressures of the subject in the systole and the diastole. When the heart murmur is recognized in the diastole, the subject is strongly suspected of suffering from the aortic valve insufficiency. This disease has a trend that the heart murmur in the diastole increases as the symptom gets worse, but the heart murmur in the diastole rather becomes weak as the symptom further becomes severe. On the other hand, a patient suffering from an end-stage aortic valve insufficiency has a trend that the pulse pressure increases. Accordingly, simultaneously measuring the pulse pressure in addition to the heart murmur in the diastole ensures a more certain diagnosis even in a case of the severe aortic valve insufficiency. 
     That is, as illustrated in  FIG. 5 , when the diastolic murmur is equal to or less than a constant threshold and the pulse pressure is equal to or less than a constant threshold, it is diagnosed that the subject is normal. On the other hand, when the diastolic murmur exceeds the constant threshold, it is diagnosed that the subject is suspected of suffering from the aortic valve insufficiency. Even when the diastolic murmur is equal to or less than the constant threshold, in a case where the pulse pressure exceeds the constant threshold, it is diagnosed that the subject is suspected of suffering from the aortic valve insufficiency. The threshold of the systolic murmur and the threshold of the pulse pressure may be appropriately adjusted. 
     In the present description, the embodiment of the present invention has been described above by referring to the drawings to express the content of the present invention. However, the present invention is not limited to the above-described embodiment and encompasses changed forms and improved forms obvious for those skilled in the art based on the matters described in the present description. 
     DESCRIPTION OF REFERENCE SIGNS 
     
         
           10  . . . device body 
           11  . . . CPU 
           12  . . . storage unit 
           13  . . . display unit 
           14  . . . operation unit 
           20  . . . cuff 
           21  . . . air bag 
           22  . . . pressure sensor 
           23  . . . oscillation circuit 
           24  . . . pump 
           25  . . . pump driving circuit 
           26  . . . pressure release valve 
           27  . . . valve driving circuit 
           28  . . . air hose 
           30  . . . probe 
           31  . . . light-emitting element 
           32  . . . light-receiving element 
           33  . . . light-emitting circuit 
           34  . . . light-receiving circuit 
           40  . . . chest piece 
           41  . . . microphone 
           42  . . . acoustic processing circuit 
           51  . . . first electrocardiograph electrode 
           52  . . . indifferent electrode 
           53  . . . second electrocardiograph electrode 
           54  . . . third electrocardiograph electrode 
           55  . . . electrocardiogram processing circuit 
           100  . . . vital sign measurement device