Patent Application
20110251501
The present invention relates to an electronic sphygmomanometer including a cuff to be attached to a blood pressure measurement site and a blood pressure calculation unit for calculating a blood pressure value from a cuff pressure, and a blood pressure measuring method using the same.
A blood pressure is one type of index for analyzing a circulatory disease. Performing risk analysis based on the blood pressure is effective in preventing cardiovascular related diseases such as apoplexy, cardiac arrest, and cardiac infarction. Conventionally, a diagnosis for performing the risk analysis is made from the blood pressure (occasional blood pressure) measured in medical institutions at the time of hospital visits and checkups. However, it is recognized from recent research that the blood pressure (home blood pressure) measured at home is more useful in diagnosing the circulatory disease than the occasional blood pressure. Accompanied therewith, the sphygmomanometer used at home is being widely used.
Most of the electronic sphygmomanometers currently being widely used use a blood pressure calculation algorithm of an oscillometric method. In the oscillometric method, a cuff is wrapped around a measurement site such as an upper arm and pressurized up to a predetermined pressure, and then depressurized gradually or in a step-wise manner. The oscillometric method is a method of detecting a change in arterial volume that occurs in the middle of depressurization as a pressure change (pressure pulse wave amplitude) superimposed on the cuff pressure, and applying a predetermined algorithm on the change in pressure pulse wave amplitude to determine the systolic blood pressure and the diastolic blood pressure. Generally, a point where the pressure pulse wave amplitude suddenly becomes large obtained during the depressurization is approximated as the systolic blood pressure, and a point where the pressure pulse wave amplitude suddenly becomes small is approximated as the diastolic blood pressure. Various algorithms have been reviewed to detect such points.
For instance, as shown in
Systolic blood pressure calculation parameter=maximum value of pressure pulse wave amplitude×α
Diastolic blood pressure calculation parameter=maximum value of pressure pulse wave amplitude×β [Equation 1]
Patent Document 1: Japanese Unexamined Patent Publication No. 3-81375
However, there is no theoretical evidence that the point where the pressure pulse wave amplitude suddenly changes matches with the systolic blood pressure and the diastolic blood pressure. Thus, the ratios (α, β) for determining the blood pressure calculation parameter had to be experimentally or statistically determined based on the change pattern (hereinafter referred to as “envelope curve”) of a great number of blood pressure values and pressure pulse wave amplitudes.
First, the pressure pulse wave amplitude is obtained by detecting a volume change of an artery transmitted to the cuff attached to the measurement site as the pressure change. The pressure pulse wave amplitude is thus subjected to the influence of the properties of the cuff. One of the properties of the cuff is an air flow rate (hereinafter referred to as cuff compliance) necessary for changing the pressure in the cuff (hereinafter referred to as cuff pressure) by 1 mmHg as shown in the graph of
The cuff compliance, which is a characteristic of the cuff, differs depending on the quality (hardness) of the measurement site. For instance, in the conventional blood pressure measurement, when two users with a different quality (hardness) of the measurement site having a change of the pressure pulse wave amplitude such that the envelope curve shape (change pattern shape of pressure pulse wave amplitude) becomes the same are measured, there is a difference in the measurement accuracy because the pressure pulse wave amplitude detected by the sphygmomanometer, that is, the envelope curve shape differs depending on the quality (hardness) of the measurement site.
Therefore, one or more embodiments of the present invention provides an electronic sphygmomanometer and a blood pressure measurement method for accurately acquiring the blood pressure value by correcting the blood pressure calculation parameter based on the information on the quality of the measurement site, thereby enhancing the satisfaction level of the user.
According to one or more embodiments of the present invention, an electronic sphygmomanometer includes a cuff to be attached to a blood pressure measurement site, pressurization and depressurization means for adjusting pressure to be applied on the cuff, pressure detection means for detecting pressure in the cuff, blood pressure calculating means for calculating a blood pressure value from the cuff pressure, recording means for recording the blood pressure value, operation means for carrying out operations such as blood pressure measurement, correcting means for correcting the blood pressure value calculated by the blood pressure calculating means based on separately acquired correction information; and information acquiring means for acquiring information on quality of the measurement site as the correction information; wherein when the information on the quality of the measurement site is acquired as the correction information by the information acquiring means, the correcting means corrects the blood pressure calculation parameter based on the information on the quality of the measurement site.
Therefore, an optimum blood pressure calculation parameter can be set for every quality of the measurement site according to the information on the quality of the measurement site, and the measurement error can be reduced.
Further, according to one or more embodiments of the invention, information on the quality of the measurement site may be information of body fat percentage, subcutaneous fat percentage, or BMI.
Further, one or more embodiments of the invention may further include display means for displaying the information on the quality of the measurement site applied when the correcting means corrects the blood pressure calculation parameter.
According to one or more embodiments of the present invention, there is provided a blood pressure measurement method for adjusting pressure to be applied to a cuff with pressurization and depressurization means when the cuff is attached to a blood pressure measurement site, and calculating a blood pressure value by blood pressure calculating means based on a cuff pressure detected by pressure detection means, the blood pressure measurement method including the step of: correcting the blood pressure value calculated by the blood pressure calculating means based on separately acquired correction information; wherein the step of correcting by the correcting means includes acquiring information on quality of the measurement site as the correction information by information acquiring means, and when the information on the quality of the measurement site is acquired as the correction information by the information acquiring means, correcting the blood pressure calculation parameter based on the information on the quality of the measurement site.
According to one or more embodiments of the present invention, a process of setting an optimum blood pressure calculation parameter for every quality of the measurement site of the user and reducing the measurement error can be executed.
According to one or more embodiments of the present invention, the electronic sphygmomanometer and the blood pressure measuring method for accurately acquiring the blood pressure value using the acquired data are provided, so that the satisfaction level of the user can be enhanced.
Embodiments of the present invention will be described below with reference to the drawings.
As shown in
The cuff 2101 is a band shaped member that is connected to the air tube 2102 and that is attached to a blood pressure measurement site of the user to pressurize by air pressure.
The pressure sensor 2103 is an electrostatic capacitance type pressure sensor, in which a capacitance value changes according to the pressure in the cuff (cuff pressure).
The pump 2104 and the valve 2105 apply pressure to the cuff and adjust (control) the pressure in the cuff.
The oscillation circuit 2111 outputs a signal of the frequency corresponding to the capacitance value of the pressure sensor 2103.
The pump drive circuit 2112 and the valve drive circuit 2113 drive the pump 2104 and the valve 2105, respectively.
The timing unit 2115 is a device for timing the current date and time, and transmitting the timed date and time to the CPU 2120 as necessary.
The power supply 2116 supplies power to each configuring unit.
The CPU 2120 executes the control of the pump 2104, the valve 2105, the display unit 2121, the memories 2122, 2123, the operation unit 2530, the interface 2171, the blood pressure determination process, and the management of the recording values.
The display unit 2121 is configured by a display device such as a liquid crystal screen, and displays a blood pressure value and user information, to be described later, according to a signal transmitted from the CPU 2120.
The memory (for processing) 2122 stores a ratio (to be described later) for determining a blood pressure calculation parameter and a control program of the sphygmomanometer.
The memory (for recording) 2123 stores the blood pressure value, and also stores the user information by association in addition to the date and time, the user, and the measurement value (blood pressure value etc.).
The operation unit 2530 includes a power supply switch 2131, a measurement switch 2132, a stop switch 2133, a record callout switch 2141, a user selection switch 2142, and a user information input switch 2543, permits the operation input such as power ON/OFF of the sphygmomanometer and the start of measurement, and transmits the input input signal to the CPU 2120.
The interface 2171 records/reads out the blood pressure to and from the external memory 2171 according to the control of the CPU 2120.
The user information input switch 2543 can input body fat percentage, subcutaneous fat percentage, BMI or the like for the information of the user, where the user information related to the quality (hardness) of the measurement site of the user can be acquired according to one or more embodiments of the present invention.
The blood pressure measurement operation using the electronic sphygmomanometer 2500 configured as above will be described according to the flowchart of
First, when the power supply switch 2131 of the sphygmomanometer is pushed (step S2501), the CPU 2120 initializes the operation memory of the sphygmomanometer, and carries out 0 mmHg adjustment of the pressure sensor 2103 (step S2502).
When the information of the user (body fat percentage, subcutaneous fat percentage, BMI, etc.) is input (step S2503), the CPU 2120 determines a blood pressure calculation parameter most suited for the user information (step S2504).
The cuff 2101 is then wrapped around the measurement site of the user, and the measurement switch 2132 is pushed (step S2505), so that the CPU 2120 pressurizes the cuff pressure up to a predetermined pressure with the pump 2104 (steps S2506 to S2507), and gradually depressurizes the cuff pressure with the valve 2105 (step S2508).
The CPU 2120 extracts the pressure change component involved in the volume change of the artery superimposed on the cuff pressure obtained during the depressurization, and calculates the blood pressure through a predetermined calculation using the optimized blood pressure calculation parameter (step S2509).
After calculating the blood pressure value (step S2510: YES), the CPU 2120 opens the valve 2105 and exhausts the air in the cuff.
The CPU 2120 displays the calculated blood pressure value, the user information, and the like on the display unit 2121 (step S2511), and records the same in the memory (for recording) 2123 in association with the user information in addition to the measurement date and time, and the user (step S2512).
The optimization process of the blood pressure calculation parameter is carried out in the following manner in step S2504.
When, for example, the body fat percentage is input for the user information (step S2503), the CPU 2120 determines the ratios α, β corresponding to the range of the body fat percentage in which the input body fat percentage is input based on a table, in which the ratios α, β for determining the blood pressure calculation parameter are categorized for every value of the body fat percentage as shown in
Similarly for the subcutaneous fat percentage and the BMI, the CPU 2120 determines the blood pressure calculation parameter as the optimum parameter using the table (not shown) corresponding to the table shown in
The CPU 2120 determines the optimum parameter based on the user information input in step S2503 in this manner.
As the user information, the value recorded in an external recording medium (USB memory, etc.) or a personal computer, or a server through the Internet may be used, or the body fat meter or the like is connected to measure the body fat percentage for every blood pressure measurement, and thus, a measured value may be used.
According to one or more embodiments of the present invention, the body fat percentage is divided into a plurality of (e.g., four) sections for every predetermined range, and the ratio α for determining the systolic blood pressure calculation parameter and the ratio β for determining the diastolic blood pressure calculation parameter are set in advance for each section.
The ratio α is the largest and 52% in the section of smaller than or equal to 19.9%, and becomes smaller as the body fat percentage becomes greater (as the body type approaches the obese body type from the standard body type). The ratio α is the smallest and 46% in the section of greater than or equal to 35%.
The ratio β is the smallest and 68% in the section of smaller than or equal to 19.9%, and becomes greater as the body fat percentage becomes greater. The ratio β is the largest and 74% in the section of greater than or equal to 35%.
In step S2511, a display as shown in
In the body fat percentage section display portion 2121b, a list is displayed according to the body fat percentage section set in the table of
However, the display method of the body fat percentage section display portion 2121b is not necessarily limited thereto, and only the section to which the body fat percentage input in step S2503 belongs may be displayed.
As described above, an electronic sphygmomanometer 2500 includes biological information acquiring means for measuring a blood pressure value, recording means (memory 2123) for recording the blood pressure value, means (memory 2122) for storing ratios for determining the blood pressure calculation parameters and a control program of the sphygmomanometer, operation means (operation unit 2530) for performing operations such as blood pressure measurement, correcting means (CPU 2120) for correcting the biological information acquired by the biological information acquiring means based on the separately acquired correction information, and output means (display unit 2121) for outputting the corrected information (blood pressure value) after the correction, the biological information acquiring means including a cuff 2101 to be attached to a blood pressure measurement site, pressurization and depressurization means 2104, 2105 for adjusting the pressure to be applied to the cuff 2101, pressure detection means (pressure sensor 2103) for detecting the pressure in the cuff, and blood pressure calculation means (CPU 2120) for calculating the blood pressure value from the cuff pressure, the electronic sphygmomanometer further including information acquiring means (CPU 2120 that executes step S2503) for acquiring information on quality (hardness) of the measurement site of the user, where the correcting means (CPU 2120 that executes step S2504) is configured to correct the blood pressure calculation parameter based on the quality of the measurement site.
According to one or more embodiments of the present invention, the optimum blood pressure calculation parameter is set for every quality (hardness) of the measurement site of the user, so that the measurement error can be reduced.
The user information such as the body fat percentage, the subcutaneous fat percentage, and the BMI is an index indicating the quality (hardness) of the measurement site of the user, and the quality of the measurement site can be numerically converted by the body fat percentage, the subcutaneous fat percentage, and the BMI. Therefore, the correcting means (CPU 2120 that executes step s2504) can easily set the blood pressure calculation parameter based on the numerically converted information by acquiring various types of user information as the information related to the quality of the measurement site.
When the user information (information related to the quality of the measurement site of the user) is not appropriately input in step S2503, the blood pressure calculation parameter is not appropriately determined in step S2504. Thus, according to one or more embodiments of the present invention, the user information input before the start of the blood pressure measurement, that is, the user information applied when setting the blood pressure calculation parameter in step S2504, is displayed on the display means (display unit 2121), so that the user can check whether or not the user information is appropriately input, and the necessity to redo the blood pressure measurement can be easily recognized based on the display of the display unit 2121 when the input user information is not appropriate. Thus, the user is able to know the accurate blood pressure value.
Embodiments of the present invention are not limited only to the above-described embodiments, and a great number of embodiments can be realized.
For example, the electronic sphygmomanometer 2500 may be configured to download an appropriate parameter, threshold value, algorithm, or the like from a dedicated server to expand the function. In this case, the version of the software may be upgraded with the hardware as is, or optimization can be easily realized by the user.
The function expansion of the electronic sphygmomanometer 2500 may be executed from a user terminal such as a personal computer possessed by the user without using the server. In this case, the parameter, the threshold value, the algorithm, and the like may be downloaded from a recording medium such as a CD-ROM.
The electronic sphygmomanometer 2500 may be directly and communicably connected wirelessly or by wire to other biological information acquiring device such as a body composition meter, a pedometer, or an electronic thermometer. In this case as well, data may be mutually transmitted and received to enhance the individual accuracy.
Embodiments of the present invention can be used in an electronic sphygmomanometer adopting an oscillometric method that uses a cuff.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-333402 | Dec 2008 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2009/007229 | Dec 2009 | US |
| Child | 13169181 | US |
