JP2011182967A - Blood pressure information measuring instrument and method of computing index of extent of arteriosclerosis by the instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure blood pressure information permitting an accurate decision to be made about the extent of arteriosclerosis. <P>SOLUTION: The measuring instrument carries out a differentiation process (S101) for a detected waveform of a pulse wave (S103), and computes 20% for example of the maximum amplitude of a differential curve as a threshold value (S105). Furthermore, the measuring instrument computes the maximum amplitude as a noise level for at least a partial range of the diastolic phase of the waveform of the pulse wave (S107) and compares the noise level with the threshold value. When the noise level is higher than the threshold value (NO at S109), the measuring instrument decides that the noise is mixed into the waveform of the pulse wave and does not use the waveform for computing the index of the extent of arteriosclerosis. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a blood pressure information measuring apparatus and a method for calculating an index of arteriosclerosis in the apparatus, and in particular, a blood pressure information measuring apparatus for measuring blood pressure information effective for determination of the arteriosclerosis degree, The present invention relates to an index calculation method.

  Conventionally, as a device for determining the degree of arteriosclerosis, for example, as disclosed in Japanese Patent Application Laid-Open No. 2000-316821 (Patent Document 1), the speed of propagation of a pulse wave ejected from the heart (hereinafter, PWV: There is a device to check (Pulse Wave Velocity). The PWV is equipped with cuffs or the like that measure pulse waves at at least two locations such as the upper arm and lower limbs, and simultaneously measures the pulse waves, so that the appearance time difference between the pulse waves at each position and the cuff that measures the pulse waves are measured. It is calculated from the length of the artery between the two points to which etc. are mounted. For this reason, it is necessary to attach cuffs or the like to at least two places, and there is a problem that it is difficult to easily measure PWV at home.

  As a technique for determining the degree of arteriosclerosis only from the pulse wave of the upper arm, Japanese Patent Application Laid-Open No. 2004-113593 (Patent Document 2) discloses a measurement device including a pulse wave measurement cuff and a compression cuff that compresses the distal side. The technique used and determined is disclosed. This technique measures the pulse wave on the central (heart) side while compressing the peripheral side, and the ejection wave ejected from the heart and the reflected wave from the iliac bifurcation and the stiffening site in the artery And the degree of arteriosclerosis is determined based on an index such as an amplitude difference between the ejection wave and the reflected wave, an amplitude ratio, or an appearance time difference.

JP 2000-316821 A JP 2004-113593 A

  In order to accurately determine the degree of arteriosclerosis using the devices disclosed in Document 1 and Document 2, in order to average fluctuations due to the breathing of the subject, the measurement part such as the upper arm is pressed with a cuff for several seconds. It is necessary to continue the measurement while maintaining a resting state for several tens of seconds from the beginning. However, in actuality, noise generated by body movement or the like is mixed in the measurement result, and thus there is a problem that the degree of arteriosclerosis calculated from the pulse wave obtained from the change in the internal pressure of the cuff includes an error.

  The present invention has been made in view of such a problem, and is a blood pressure information measuring device for measuring blood pressure information capable of accurately determining the degree of arteriosclerosis, and a method for calculating an index of arteriosclerosis in the device. The purpose is to provide.

  In order to achieve the above object, according to one aspect of the present invention, the blood pressure information measurement device is a blood pressure information measurement device that calculates an index of the degree of arteriosclerosis of a measurement subject as blood pressure information, and includes: A first sensor for detecting the internal pressure of the first air bag as blood pressure information, and an arithmetic means for calculating an index of the degree of arteriosclerosis based on a change in the internal pressure of the first air bag. The means includes a detecting means for detecting a pulse wave waveform for one beat from a change in internal pressure of the air bag, and a determination for determining whether noise is mixed in the detected pulse wave waveform for one beat. Means, and first calculation means for calculating an index of the degree of arteriosclerosis using the pulse wave waveform determined by the determination means as not containing noise.

  Preferably, the blood pressure information measurement device further includes notification means for notifying that if the determination means determines that noise is mixed in the pulse wave waveform for one beat.

  Preferably, the determination means compares the amplitude of the differential curve of at least a part of the range of the pulse wave waveform for one beat with a predetermined threshold value, and when the amplitude is larger than the threshold value, It is determined that noise is mixed in the pulse wave waveform for the beat.

  More preferably, at least a part of the above-described pulse wave waveform for one beat is included in the diastole of the pulse wave waveform.

  More preferably, the calculation means further includes second calculation means for calculating the predetermined threshold value based on the amplitude of the differential curve of the pulse wave waveform for one beat.

  Preferably, the calculation means further includes third calculation means for calculating a value for determination from a pulse wave waveform for one beat, and the determination means is obtained from each of a plurality of continuous pulse wave waveforms. Regarding a plurality of determination values, when there is a difference from the average value thereof that is greater than a predetermined threshold value, the difference among a plurality of continuous pulse wave waveforms is greater than the predetermined threshold value. It is determined that noise is mixed in a large pulse wave waveform.

  More preferably, the third calculation means calculates an index of the degree of arteriosclerosis from a pulse wave waveform for one beat as a determination value.

  More preferably, the determination unit calculates the predetermined threshold value based on a standard deviation of a plurality of determination values.

  Preferably, the blood pressure information measuring device further includes a second air bag and a second sensor for detecting the internal pressure of the second air bag as blood pressure information, and the calculating means changes the internal pressure of the first air bag. Instead of calculating the index of the degree of arteriosclerosis based on the change in the internal pressure of the second air bag, and the detection means is such that the first air bag is the distal side of the measurement site and the second air bag is the central side of the measurement site. The pulse for one beat from the change in the internal pressure of the second air bag when the first air bag is in the blood-feeding state by pressing the distal side of the measurement site so that Detect wave waveforms.

  According to another aspect of the present invention, a method for calculating an index of arteriosclerosis includes an air bag, a sensor for detecting the internal pressure of the air bag as blood pressure information, and the degree of arteriosclerosis based on a change in the internal pressure of the air bag. A method for calculating an index of arteriosclerosis in a blood pressure information measuring device including a calculation means for calculating an index, the step of detecting a pulse wave waveform for one beat from a change in internal pressure, and a pulse for one beat Determining whether or not noise is mixed in the waveform, and calculating an index of the degree of arteriosclerosis using the pulse waveform determined that noise is not mixed in the determining step.

  According to this invention, it becomes possible to detect a pulse wave in which noise is mixed from the measured pulse wave waveform, and by calculating an index of the degree of arteriosclerosis using a pulse wave in which noise is not mixed The degree of arteriosclerosis can be determined with higher accuracy than in the past.

It is a perspective view which shows the specific example of the external appearance of the measuring apparatus concerning embodiment. It is a schematic cross section which shows the specific example of the measurement attitude | position at the time of measuring blood pressure information using a measuring apparatus, and the structure of an armband. It is a figure which shows the example (A) of the pulse-wave waveform in which noise is not mixed, and the example (B) of the differential curve. It is a figure which shows the example (A) of the pulse-wave waveform in which noise is mixed, and the example (B) of the differential curve. It is a figure showing the functional block of the measuring device concerning a 1st embodiment. It is a flowchart which shows the specific example of operation | movement with a measuring apparatus. It is a flowchart which shows the specific example of the operation | movement for extracting the feature point in the operation | movement of FIG. 6 concerning 1st Embodiment. It is a figure which shows the pressure change in each air bag during operation | movement with a measuring apparatus. It is a figure showing the functional block of the measuring apparatus concerning 2nd Embodiment. It is a flowchart which shows the specific example of the operation | movement for extracting the feature point in the operation | movement of FIG. 6 concerning 2nd Embodiment. It is a figure which shows the specific example of the correlation with the appearance time difference Tr and PWV between an ejection wave and a reflected wave.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same.

  Referring to FIG. 1, a blood pressure information measuring device (hereinafter abbreviated as a measuring device) 1 according to an embodiment is connected to a base 2 and an arm band 9 that is connected to the base 2 and is attached to an upper arm that is a measurement site. These are connected by an air tube 10. On the front surface of the substrate 2, a display unit 4 that displays various information including measurement results and an operation unit 3 that is operated to give various instructions to the measuring apparatus 1 are arranged. The operation unit 3 includes a switch 31 that is operated to turn on / off the power source and a switch 32 that is operated to instruct the start of measurement.

  2A and 2B, the armband 9 includes an air bag as a fluid bag for compressing the living body. The air bag includes an air bag 13A that is a fluid bag used to measure blood pressure as blood pressure information, and an air bag 13B that is a fluid bag used to measure pulse waves as blood pressure information. The size of the air bag 13B is, for example, about 20 mm × 200 mm. Preferably, the air capacity of the air bag 13B is 1/5 or less compared to the air capacity of the air bag 13A.

  When measuring the pulse wave using the measuring apparatus 1, as shown in FIG. 2A, the arm band 9 is wound around the upper arm 100 which is a measurement site. By pressing the switch 32 in this state, blood pressure information is measured, and an index for determining the degree of arteriosclerosis is calculated based on the blood pressure information. Here, “blood pressure information” refers to information related to blood pressure obtained by measurement from a living body, and specifically corresponds to a blood pressure value, a pulse wave waveform, a heart rate, and the like.

  Examples of indexes for determining the degree of arteriosclerosis include Tr (Traveling time to reflected wave), AI (Augmentation Index), and Tpp (also expressed as ΔTp).

  Tr is represented by a time interval between the appearance time of the ejection wave and the appearance time of the reflected wave in which the traveling wave is reflected back from the bifurcation of the iliac artery. Specifically, FIG. 3 corresponds to the pulse wave inflection point representing the rising point of the reflected wave in FIG. 3A from the characteristic point P1 representing the rising point of the ejection wave in the differential curve of FIG. It is represented by the time interval to the feature point P3 in (B). When the measurement site is the upper arm and the reflected wave is a reflected wave from the ankle as the periphery, the correlation between the time difference Tr and PWV can be statistically obtained by obtaining individual parameters such as height and sex, for example, London GM As shown in FIG. 11 described in the paper published in “Hypertension” (1992 Jul; 20 (1): 10-19.). Therefore, the appearance time difference Tr between the ejection wave and the reflected wave can be used as an index for determining the degree of arteriosclerosis.

  Tpp is represented by the time interval between the appearance time of the peak (maximum point) of the ejection wave, which is a traveling wave, and the appearance time of the peak (maximum point) of the reflected wave. Specifically, it is represented by a time interval from the feature point P2 representing the peak of the ejection wave to the feature point P4 representing the peak of the reflected wave in the differential curve of FIG. Similarly to Tr, Tpp can also be used as an index for determining the degree of arteriosclerosis.

  AI is represented by the ratio of the amplitude at the peak (maximum point) of the reflected wave to the amplitude at the peak (maximum point) of the ejection wave that is a traveling wave. Specifically, the peak of the reflected wave is represented in the differential curve (B) of the amplitude A2 in the pulse wave waveform (A) corresponding to the feature point P2 representing the peak of the ejection wave in the differential curve (B) of FIG. It is expressed as a ratio to the amplitude A4 in the pulse wave waveform (A) corresponding to the feature point P4. AI mainly reflects the reflection intensity of the pulse wave corresponding to arteriosclerosis (which is a reflection phenomenon of the pulse wave and represents the ease of receiving the blood flow to be delivered). It can be an index for performing.

  However, as shown in the pulse waveform (A) of FIG. 4, when noise due to body motion or the like is mixed into the pulse waveform, the position of the inflection point obtained from the characteristic point P2 ′ of the differential curve (B) is 3 may deviate from the pulse wave waveform (A). Therefore, if noise is mixed in the pulse wave waveform, an error is generated in the calculation result of the degree of arteriosclerosis.

[First Embodiment]
The normal pulse wave waveform without noise is gradually lowered in the interval from the notch to the next pulse wave rise, as shown in the pulse wave waveform (A) of FIG. To do. Therefore, the portion corresponding to the expansion period of the pulse wave in the differential curve (B) in FIG. 3 is flat. The “notch” refers to a small vibration caused by aortic valve closure. The pulse wave waveform for one beat is distinguished from the systole from the rising point to before the notch, and from the diastole from the notch to the rising point of the next pulse wave waveform. However, when noise is mixed in the pulse wave waveform, the portion corresponding to the diastole does not become flat as shown in the differential curve (B) in FIG. 4 and repeats vibration according to the magnitude of the noise. Here, in the following description, the maximum amplitude value within the analysis target range in the differential curve corresponding to the expansion period of the pulse wave waveform is defined as “noise level”.

  Therefore, the measuring apparatus 1A according to the first embodiment detects a pulse wave waveform in which noise is mixed from the pulse wave waveform measured based on this phenomenon, and uses the pulse wave waveform used for calculating the index of the degree of arteriosclerosis. Exclude from

  A functional block of the measurement apparatus 1A for detecting a pulse wave waveform mixed with noise and calculating an index of the degree of arteriosclerosis by excluding the pulse wave waveform will be described with reference to FIG. Referring to FIG. 5, measuring apparatus 1A includes an air system 20A connected to air bag 13A via air tube 10, an air system 20B connected to air bag 13B via air tube 10, and a CPU ( Central Processing Unit) 40. The air system 20A includes an air pump 21A, an air valve 22A, and a pressure sensor 23A. The air system 20B includes an air valve 22B and a pressure sensor 23B.

  The air pump 21A is connected to the drive circuit 26A, and the drive circuit 26A is further connected to the CPU 40. The air pump 21A is driven by a drive circuit 26A that has received a command from the CPU 40, and pressurizes the air bag 13A by sending compressed gas into the air bag 13A.

  The air valve 22A is connected to the drive circuit 27A, and the drive circuit 27A is further connected to the CPU 40. The air valve 22B is connected to the drive circuit 27B, and the drive circuit 27B is further connected to the CPU 40. The open / close states of the air valves 22A and 22B are controlled by drive circuits 27A and 27B, respectively, which have received a command from the CPU 40. By controlling the open / close state, the air valves 22A and 22B maintain or depressurize the pressure in the air bags 13A and 13B, respectively. Thereby, the pressure in air bag 13A, 13B is controlled.

  The pressure sensor 23A is connected to an amplifier 28A, the amplifier 28A is further connected to an A / D converter 29A, and the A / D converter 29A is further connected to the CPU 40. The pressure sensor 23B is connected to the amplifier 28B, the amplifier 28B is further connected to the A / D converter 29B, and the A / D converter 29B is further connected to the CPU 40. The pressure sensors 23A and 23B detect pressures in the air bags 13A and 13B, respectively, and output signals corresponding to the detected values to the amplifiers 28A and 28B. The output signals are amplified by the amplifiers 28A and 28B, digitized by the A / D converters 29A and 29B, and then input to the CPU 40.

  The air tube from the air bag 13 </ b> A and the air tube from the air bag 13 </ b> B are connected by a two-port valve 51. The 2-port valve 51 is connected to the drive circuit 53, and the drive circuit 53 is further connected to the CPU 40. The 2-port valve 51 has a valve on the air bag 13A side and a valve on the air bag 13B side, and these valves open and close by being driven by a drive circuit 53 that receives a command from the CPU 40.

  The memory 41 stores a program executed by the CPU 40. The CPU 40 reads out and executes a program from the memory 41 based on a command input to the operation unit 3 provided on the base 2 of the measuring apparatus, and outputs a control signal according to the execution. Further, the CPU 40 outputs the measurement result to the display unit 4 and the memory 41. In addition to storing the measurement results, the memory 41 stores information about the measurer including at least the age as required. And CPU40 reads the information regarding the said measurer with the execution of a program as needed, and uses it for a calculation.

  As a function for calculating an index of the degree of arteriosclerosis after excluding a pulse wave waveform mixed with noise, the CPU 40 receives a pressure signal input from the pressure sensor 23B and detects a pulse wave waveform. 401, a processing unit 402 for executing differential calculation processing such as fourth-order differential calculation and second-order differential calculation on the detected pulse waveform, and determination processing described later from a differential curve obtained by the differential calculation processing A threshold value calculation unit 403 for calculating a threshold value to be used, a noise level calculation unit 404 for calculating the above-mentioned noise level from a differential curve obtained by differential operation processing, a calculated threshold value and noise A determination unit 405 for determining whether or not noise is mixed in the pulse wave waveform detected by comparing the level, and it is determined that noise is mixed. Including index calculation unit 406 for calculating an index of the degree of arteriosclerosis by using a pulse waveform other than the pulse waveform which is. These are functions mainly formed in the CPU 40 when the CPU 40 reads out and executes a program stored in the memory 41 in accordance with an operation signal from the operation unit 3, but at least some of these functions have a hardware configuration. May be formed.

  The operation of the measurement apparatus 1A will be described using the flowchart of FIG. The operation shown in FIG. 6 is started when the measurer presses the switch 32. This operation is realized by the CPU 40 reading a program stored in the memory 41 and controlling each unit shown in FIG. Moreover, the pressure change in the air bags 13A and 13B during operation in the measuring apparatus 1A will be described with reference to FIG. 8A shows the time change of the pressure P1 in the air bag 13B, and FIG. 8B shows the time change of the pressure P2 in the air bag 13A. S3 to S17 attached to the time axis in FIGS. 8A and 8B coincide with each operation of the measurement operation in the measurement apparatus 1A described later.

  Referring to FIG. 6, when the operation is started, each unit is initialized in CPU 40 in step S1. In step S3, the CPU 40 outputs a control signal to the air system 20A to start pressurization of the air bag 13A, and measures blood pressure in the pressurization process. The blood pressure in step S3 is measured by an oscillometric method that is performed with a normal sphygmomanometer.

  When the blood pressure measurement in step S3 is completed, the CPU 40 outputs a control signal to the drive circuit 53 in step S5 to open both the air bag 13A side valve and the air bag 13B side valve of the 2-port valve 51. . As a result, the air bag 13A and the air bag 13B communicate with each other, a part of the air in the air bag 13A moves to the air bag 13B, and the air bag 13B is pressurized.

  In the example of FIG. 8A, the pressure P2 in the air bladder 13A increases to a pressure higher than the maximum blood pressure value from the start of pressurization in step S3 until the blood pressure measurement is completed. Thereafter, when the valve of the 2-port valve 51 is opened in step S5, part of the air in the air bag 13A moves to the air bag 13B, and the pressure P2 decreases. At the same time, as shown in FIG. 8B, the pressure P1 in the air bladder 13B increases rapidly. When the pressure P1 and the pressure P2 coincide, that is, when the internal pressures of the air bags 13A and 13B change, the movement of air from the air bag 13A to the air bag 13B ends. In step S7, the CPU 40 outputs a control signal to the drive circuit 53 at this time, and closes both valves of the 2-port valve 51 opened in step S5. 8A and 8B show that the pressure P1 and the pressure P2 match at the time of step S7. As shown in FIG. 2A, since the capacity of the air bag 13B is smaller than the capacity of the air bag 13A, the decrease in the pressure P2 in step S5 is not significant, and the pressure P1 at the time of step S7. The pressure P2 is higher than the maximum blood pressure value.

  Thereafter, in step S9, the CPU 40 outputs a control signal to the drive circuit 27B, and adjusts the pressure P1 in the air bladder 13B to a pressure suitable for measuring the pulse wave. The decompression adjustment amount here is preferably about 5.5 mmHg / sec, for example. Moreover, as a pressure suitable for measuring a pulse wave, about 50-150 mmHg is suitable. At this time, since both valves of the 2-port valve 51 are closed, as shown in FIG. 8B, the pressure P2 in the air bag 13A is higher than the maximum blood pressure value at the peripheral side of the measurement site. It is under pressure and is in a state of thrush.

  In the operation according to the first embodiment, each time a pulse wave waveform for one beat based on the pressure signal from the pressure sensor 23B is input in step S11 in a state where the peripheral side is driven, the pulse wave is inputted. An operation for extracting feature points from the waveform is performed. Specifically, referring to the flowchart of FIG. 7, in step S101, the detection unit 401 receives an input of a pressure signal from the pressure sensor 23B and detects a pulse wave waveform. In step S103, the processing unit 402 performs differentiation processing such as fourth-order differentiation processing on the detected pulse wave waveform.

  In step S <b> 105, the threshold value calculation unit 403 calculates a threshold value used in the subsequent determination process from the differential curve of the pulse waveform for one beat obtained as a result of the differential process. An example of the threshold value is a prescribed ratio of the maximum amplitude of the differential curve for one beat, and an example of the prescribed ratio is 20%.

  In step S107, the noise level calculation unit 404 calculates the noise level from the differential curve of the pulse waveform for one beat obtained as a result of the differential processing. Specifically, the noise level calculation unit 404 detects a notch from the pulse wave waveform, and specifies a position corresponding to the notch on the differential curve. The method of detecting a notch from a differential waveform is not limited to a specific method, For example, the method currently disclosed by Unexamined-Japanese-Patent No. 2004-0000422 is employable. Specifically, the noise level calculation unit 404 detects the first minimum point or inflection point after the peak (maximum point) as a notch from the pulse wave waveform. The noise level calculation unit 404 then determines the maximum amplitude value of the differential curve in the range to be analyzed (for example, the entire range of diastole) in the diastole, which is the interval from the detected notch to the rise of the next pulse wave waveform. The noise level is calculated.

  The determination unit 405 determines whether noise is mixed in the input pulse waveform by comparing the noise level calculated in step S107 with the threshold value calculated in step S105. That is, as a result of the comparison, if the noise level is less than the threshold value (YES in step S109), the determination unit 405 determines that noise is not mixed in the pulse wave waveform. In this case, the pulse wave waveform gradually falls during the diastole as shown in FIG. If determined in this way, in step S111, the index calculation unit 406 calculates the characteristic points of the pulse wave waveform specified by the minimum points and zero cross points of the differential curve obtained as a result of the differential processing in step S103.

  On the other hand, as a result of the comparison, if the noise level is equal to or higher than the threshold value (NO in step S109), the determination unit 405 determines that noise is mixed in the pulse wave waveform. In this case, the differential curve repeats vibration even in the analysis target range as shown in FIG. If it is determined in this manner, in step S113, the CPU 40 performs processing for notifying the pulse wave waveform that noise is mixed, for example, on the display unit 4 or the like, and calculates a feature point from the pulse wave waveform. The process for extracting feature points ends without performing the above process.

  The operation of extracting the feature points in step S11 is a pulse wave for one beat until the number of feature points (for example, for 10 beats) necessary for calculating a predetermined index of arteriosclerosis is extracted. Repeated every time a waveform is input. Meanwhile, the pressure P1 in the air bag 13B is maintained at a pressure suitable for measuring a pulse wave as shown in FIG. 8A, and the pressure P2 in the air bag 13A is shown in FIG. 8B. As shown, the pressure is maintained higher than the maximum blood pressure value. Thereby, the peripheral blood-feeding state of the measurement site is maintained.

  When the number of extracted feature points reaches a predetermined number (for example, 10 beats) (YES in step S13), in step S15, the index calculation unit 406 uses the average value of the extracted feature points. An index of the degree of arteriosclerosis such as Tr is calculated. In step S17, the CPU 40 outputs a control signal to the drive circuits 27A and 27B to open the air valves 22A and 22B, thereby releasing the pressure in the air bags 13A and 13B to atmospheric pressure. In the example of FIGS. 8A and 8B, the pressures P1 and P2 rapidly decrease to atmospheric pressure in the section of step S17.

  Processing for displaying the measurement results such as the calculated maximum blood pressure value (SYS), minimum blood pressure value (DIA), arteriosclerosis index, and measured pulse wave waveform on the display unit 4 provided on the base 2 Will be displayed.

  Thus, in measuring apparatus 1A, it is determined whether noise is mixed for each beat of the measured pulse wave waveform. The pulse wave waveform determined to contain noise is not used to calculate an index of the degree of arteriosclerosis. As a result, an index of the degree of arteriosclerosis such as Tr is calculated with high accuracy, and the degree of arteriosclerosis can be determined with higher accuracy than before. Further, in the determination operation according to the first embodiment, each time the pulse wave waveform is measured, it is determined whether or not noise is mixed in the pulse wave waveform in the pulse wave waveform for one beat. Is possible.

[Second Embodiment]
As shown in the pulse wave waveform (A) in FIG. 3 and the pulse wave waveform (A) in FIG. 4, the pulse wave waveform is obtained from the characteristic points of the differential curve by mixing noise due to body movement or the like. The position of the inflection point is shifted, and as a result, the calculation result of the degree of arteriosclerosis calculated using the pulse wave waveform mixed with noise is shifted from that calculated using the pulse wave waveform not mixed with noise. There is. For this reason, the calculation result of the degree of arteriosclerosis calculated using each of the continuous pulse wave waveforms varies.

  Therefore, the measuring apparatus 1B according to the second embodiment detects a pulse wave waveform in which noise is mixed from the pulse wave waveform measured using variation in the calculation result of the arteriosclerosis degree, and an index of the arteriosclerosis degree is obtained. Excluded from the pulse waveform used for calculation.

  The functional blocks of the measuring apparatus 1B according to the second embodiment will be described with reference to FIG. Among the configurations shown in FIG. 9, configurations having the same reference numerals as those of the measurement apparatus 1 </ b> A shown in FIG. 5 are the same.

  The CPU 40 of the measuring device 1B detects the pulse waveform by receiving the input of the pressure signal from the pressure sensor 23B as a function for calculating the index of the degree of arteriosclerosis after excluding the pulse waveform in which noise is mixed. A detection unit 401 for determining, an index calculation unit for determination 407 for calculating an index (value) for use in determining whether noise such as Tr is mixed based on the detected pulse wave waveform, A determination unit 405 for determining whether or not noise is mixed in the pulse wave waveform detected using the measured index, and a pulse wave waveform other than the pulse wave waveform determined to contain noise An index calculation unit 406 for calculating an index of the degree of arteriosclerosis. These are also functions mainly formed in the CPU 40 when the CPU 40 reads out and executes a program stored in the memory 41 in accordance with an operation signal from the operation unit 3, but at least some of these functions are hardware. It may be formed of a configuration.

  In the measurement apparatus 1B, the same operation as that of the measurement apparatus 1A described in the flowchart of FIG. 6 is performed. In step S11 during the operation according to the second embodiment, every time a predetermined number N of pulse wave waveforms based on the pressure signal from the pressure sensor 23B are input in a state where the peripheral side is driven, those pulses are input. An operation for extracting a pulse wave waveform in which noise is mixed from the wave waveform and extracting a feature point using each of the other pulse wave waveforms is performed. Specifically, referring to the flowchart of FIG. 10, after the variable i representing the number of pulse wave waveforms input in step S201 is initialized to 1, the detection unit 401 in step S203 detects the pressure signal from the pressure sensor 23B. An input is received and a pulse wave waveform i corresponding to the variable i is detected. In step S205, the determination index calculation unit 407 calculates an index i corresponding to the variable i, such as Tr, as a determination index from the pulse wave waveform i detected in step S203.

  The calculation of the index for determination from the detected pulse wave waveform is repeated until the Nth pulse wave waveform N is detected (steps S207 and S209), and as a result, the indices i to N corresponding to the variables i to N, respectively. N is calculated.

  When N determination indexes i to N are calculated (NO in step S207), the determination unit 405 calculates an average value avg and a standard deviation sd of the indexes i to N in step S211. Then, the determination unit 405 compares the difference between the average value avg and the predetermined value obtained from the standard deviation sd for each of the determination indices i, and thereby the pulse waveform corresponding to each of the determination indices i. Whether or not noise is mixed is determined. An example of a predetermined value obtained from the standard deviation sd is a value twice as large as the standard deviation sd.

  That is, as a result of comparison, when the difference from the average value avg of the index i for determination is less than twice the standard deviation sd (YES in step S215), the determination unit 405 determines the pulse wave waveform corresponding to the index i. It is determined that no noise is mixed. If determined in this way, the feature point of the pulse wave waveform is calculated in the index calculation unit 406 in step S217.

  On the other hand, as a result of the comparison, when the difference from the average value avg of the index i for determination is more than twice the standard deviation sd (NO in step S215), the determination unit 405 determines the pulse wave corresponding to the index i. It is determined that noise is mixed in the waveform. If it is determined in this way, in step S219, the CPU 40 performs processing for notifying the pulse wave waveform that noise is mixed, for example, on the display unit 4 or the like, and calculates a feature point from the pulse wave waveform. The determination on the pulse wave waveform ends without the above process.

  The above determination is performed for each detected pulse wave waveform, and is repeated until the determination for the Nth pulse wave waveform N is completed (steps S221 and S223). As a result, a feature point is calculated from a pulse wave waveform in which noise is not mixed among pulse wave waveforms i to N corresponding to the variables i to N, respectively.

  As described above, the measurement apparatus 1B determines whether or not noise is mixed in each pulse wave waveform based on the variation of the determination value (index) in the measured continuous pulse wave waveform. The pulse wave waveform determined to contain noise is not used to calculate an index of the degree of arteriosclerosis. As a result, an index of the degree of arteriosclerosis such as Tr is calculated with high accuracy, and the degree of arteriosclerosis can be determined with higher accuracy than before. Furthermore, in the determination operation according to the second embodiment, it is possible to determine whether or not noise is mixed in each pulse wave waveform in a plurality of continuous pulse wave waveforms.

  In the above description, as shown in FIG. 2 (A), FIG. 2 (B), FIG. 5 and the like, the armband 9 includes two air bags 13A and 13B, which are shown in FIG. As described above, the pulse wave waveform is based on the change in the internal pressure of the central air bag 13B when the peripheral air bag 13A is in a blood-feeding state by pressing the measurement site with a pressure higher than the maximum blood pressure value. Has been measured. However, the measurement of the pulse wave waveform is not limited to such an example. That is, the central air bag 13B is not provided, and the pulse wave waveform may be measured based on a change in internal pressure of a single air bag pressed against a measurement site such as the upper arm.

  When the pulse wave waveform is measured based on the change in the internal pressure of a single air bag, the CPU 40 pressurizes the air bag to a maximum blood pressure value or more to bring the measurement site into a blood-feeding state, and then changes the internal pressure. Based on this, the pulse wave is measured for calculating the arteriosclerosis index. When a single air bag is used for measurement in this way, a sufficient compression force is required for the measurement site in order to measure blood pressure, so that the required capacity of the air bag is increased. As the capacity of the air bag increases, the pulse wave detection sensitivity for calculating the arteriosclerosis index decreases. Therefore, when using a single air bag for measurement, the accuracy of the calculated arteriosclerosis index may be reduced. Therefore, preferably, as shown in the drawing, the measuring apparatus 1 is provided with air having a small capacity on the central side in addition to the air bag having a large capacity. As a result, the measuring apparatus 1 can detect the pulse wave with higher sensitivity, and can calculate the arteriosclerosis index with high accuracy.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1,1A, 1B measuring device, 2 base, 3 operation unit, 4 display unit, 9 armband, 10 air tube, 13A, 13B air bag, 20A, 20B air system, 21A air pump, 22A, 22B air valve, 23A, 23B Pressure sensor, 26A, 27A, 27B, 53 drive circuit, 28A, 28B amplifier, 29A, 29B A / D converter, 31, 32 switch, 40 CPU, 41 memory, 512 2-port valve, 100 upper arm, 401 detector, 402 processing unit, 403 threshold calculation unit, 404 noise level calculation unit, 405 determination unit, 406 index calculation unit, 407 determination index calculation unit.

Claims (10)

A blood pressure information measuring device that calculates an index of the degree of arteriosclerosis of a measurement subject as blood pressure information,
A first air bag;
A first sensor for detecting the internal pressure of the first air bag as blood pressure information;
Calculating means for calculating an index of the degree of arteriosclerosis based on a change in internal pressure of the first air bag,
The computing means is
Detection means for detecting a pulse wave waveform for one beat from the internal pressure change;
Determination means for determining whether noise is mixed in the pulse waveform for one beat;
A blood pressure information measuring device, comprising: a first calculating means for calculating an index of the degree of arteriosclerosis using a pulse wave waveform determined by the determining means that noise is not mixed.   The blood pressure information measurement device according to claim 1, further comprising notification means for notifying that the determination means determines that noise is mixed in the pulse wave waveform for one beat.   The determination means compares the amplitude of a differential curve of at least a part of the range of the pulse waveform for one beat with a predetermined threshold value, and when the amplitude is larger than the threshold value, The blood pressure information measurement device according to claim 1 or 2, wherein it is determined that noise is mixed in a pulse wave waveform for one beat.   The blood pressure information measurement device according to claim 3, wherein a range of at least a part of the pulse wave waveform for one beat is included in an diastolic period of the pulse wave waveform.   The blood pressure according to claim 3 or 4, wherein the calculation means further includes second calculation means for calculating the predetermined threshold value based on an amplitude of a differential curve of the pulse wave waveform for one beat. Information measuring device. The calculation means further includes third calculation means for calculating a value for determination from the pulse wave waveform for one beat,
When the determination means has a plurality of determination values obtained from each of a plurality of continuous pulse wave waveforms, a difference from an average value thereof is larger than a predetermined threshold value, The blood pressure information measurement device according to claim 1 or 2, wherein it is determined that noise is mixed in a pulse wave waveform whose difference among a plurality of pulse wave waveforms is larger than the predetermined threshold value.   The blood pressure information measurement device according to claim 6, wherein the third calculation unit calculates an index of the degree of arteriosclerosis from the pulse waveform for one beat as the determination value.   The blood pressure information measurement device according to claim 6 or 7, wherein the determination unit calculates the predetermined threshold value based on a standard deviation of the plurality of determination values. A second air bag;
A second sensor for detecting the internal pressure of the second air bag as blood pressure information,
The calculation means calculates an index of the degree of arteriosclerosis based on an internal pressure change of the second air bag instead of an internal pressure change of the first air bag,
The detection means is mounted on the measurement site such that the first air bag is on the distal side of the measurement site and the second air bag is on the central side of the measurement site, and the first air bag is The pulse wave waveform for the one beat is detected from a change in internal pressure of the second air bag when the peripheral side of the measurement site is pressed to achieve a blood-feeding state. The blood pressure information measuring device described in 1. A method for calculating an index of arteriosclerosis in a blood pressure information measuring device,
The blood pressure information measuring device includes an air bag, a sensor for detecting an internal pressure of the air bag as blood pressure information, and an arithmetic means for calculating an index of the degree of arteriosclerosis based on a change in the internal pressure of the air bag. Prepared,
Detecting a pulse wave waveform for one beat from the internal pressure change;
Determining whether noise is mixed in the pulse waveform for one beat; and
Calculating the arteriosclerosis index using the pulse wave waveform determined to be free of noise in the determining step.

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