Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording for evaluating the cardiovascular system, e.g. pulse, heart rate, blood pressure or blood flow
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording for evaluating the cardiovascular system, e.g. pulse, heart rate, blood pressure or blood flow
  • A61B5/021—Measuring pressure in heart or blood vessels
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording for evaluating the cardiovascular system, e.g. pulse, heart rate, blood pressure or blood flow
  • A61B5/021—Measuring pressure in heart or blood vessels
  • A61B5/022—Measuring pressure in heart or blood vessels by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
  • A61B5/316—Modalities, i.e. specific diagnostic methods
  • A61B5/318—Heart-related electrical modalities, e.g. electrocardiography [ECG]
  • A61B5/346—Analysis of electrocardiograms
  • A61B5/349—Detecting specific parameters of the electrocardiograph cycle
  • A61B5/352—Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval

Definitions

• the present invention relates to a device for continuously measuring biological information that can continuously obtain an optimized estimate of a subject's systolic blood pressure using an electrocardiogram and blood flow pulse wave.
• the pulse wave transit time (PTT) related to blood pressure values is calculated based on an electrocardiogram obtained from an electrocardiograph, and the pulse wave obtained from a pulse wave meter worn on a fingertip and the distance from the heart to the location where the pulse wave meter sensor is attached are measured, and the systolic blood pressure and diastolic blood pressure are estimated from a formula for calculating blood pressure-related values.
• This calculation method requires the distance value from the subject's heart to the pulse wave measurement unit, and may require pre-setting for measurement.
• Ryuta Mizuguchi "Wireless Monitoring of Continuous Systolic Blood Pressure in Daily Life Using a Neckband Device," Life Support, Vol. 34, No.
• PTT -2 is proportional to systolic blood pressure, and systolic blood pressure can be obtained as an estimated value, and there is no need to measure the distance from the subject's heart to the pulse wave measurement unit.
• JP 2020-142070 A describes that the state of blood pressure (rate of change) for estimated systolic blood pressure (SBP) is measured using blood flow components and an electrocardiogram, and that information on estimated blood pressure values can be obtained.
• blood pressure information can be obtained simply by attaching and wearing a probe sensor or electrodes, without applying pressure to the body, which broadens the scope of long-term monitoring of blood pressure-related information.
• numerically obtained blood pressure information often contains errors, and although the results are obtained as estimated values, it is preferable to be able to obtain more accurate values of continuous changes in blood pressure.
• blood pressure information When blood pressure information is calculated, it is only a rough estimate, and generally, when blood flow is closed within the body, pinpoint blood pressure is measured.
• fields such as hemodialysis and apheresis, where blood is extracted externally and operations such as the removal of waste products and fluids are performed, the blood flow is equivalent to an open circuit, resulting in the addition of a rhythm different from the biological rhythm.
• fluctuations in blood pressure such as sudden hypotension, can occur that affect life prognosis, so a system that monitors changes in blood pressure and blood flow information over time and can detect sudden drops in blood pressure is desirable.
• the present invention has been achieved in view of the above problems, an optical blood flow measuring means for detecting a blood flow pulse wave from a living body; an electrocardiogram signal detection means for detecting an electrocardiogram signal from a living body; a biosignal measuring means for measuring a target biosignal and detecting a measured value of the biosignal; a biosignal calculation means for calculating a target biosignal based on the characteristic signals obtained from the optical blood flow measurement means and the electrocardiogram signal detection means; and a biosignal processing means for mathematically optimizing the actual measured signal obtained by the biosignal measurement means, the calculated signal obtained by the biosignal calculation means, and the actually measured biosignal to output an optimized biosignal.
• the present invention provides a biological information continuous measurement device equipped with the above.
• the continuous biological information measurement device of the present invention uses a formula for the estimation of systolic blood pressure, systolic blood pressure change, etc. by adding variable multipliers to parameters such as RR, C, and Tu shown in the following formula (1), and then substituting various values for these variables to compare the values obtained from the formula with the corresponding actually measured biological information. For example, the value that minimizes the difference is found, and the multiplier value at that minimum is used to set an algorithm (arithmetic formula), thereby reducing errors and obtaining optimized biological information.
• the continuous biological information measuring device of the present invention can measure continuous estimated systolic blood pressure values non-invasively by measuring electrocardiograms and blood flow pulse waves, making it possible to collect information related to blood pressure, such as systolic blood pressure values and changes in systolic blood pressure. Furthermore, the continuous biological information measuring device of the present invention can continuously display arteriosclerosis information and estimated blood pressure information obtained from blood flow information as biological information.
• the continuous biological information measurement device of the present invention detects fluctuations in blood pressure and blood flow-related information during hemodialysis treatment and other blood purification therapies, and responds predictively to these fluctuations, enabling stabilization processing and achieving gentle dialysis treatment.
• the continuous biological information measuring device of the present invention displays information related to blood pressure fluctuations in real time during treatments that affect blood pressure fluctuations, such as blood purification therapy, which controls blood moisture content or removes uremic toxins, enabling predictive monitoring of a patient's blood pressure fluctuations.
• FIG. 1 is a diagram showing an embodiment of a biological information continuous measuring device according to the present invention.
• FIG. 2 is a block diagram for explaining an embodiment of the biological information continuous measuring device of the present invention.
• FIG. 3 is a diagram illustrating an embodiment of the present invention.
• FIG. 4 shows the results of an experiment conducted to explain one embodiment of the present invention.
• FIG. 5 shows the results of an experiment conducted to explain one embodiment of the present invention.
• 6(a) and (b) are diagrams illustrating a method for measuring changes in blood pressure due to exercise stress.
• FIG. 7 is a graph showing the measurement results of blood pressure changes.
• FIG. 8 is a graph showing continuous blood pressure measurements according to the present invention.
• the optical blood flow measurement means in this invention includes reflective or transmissive sensors that use a laser light-emitting element or LED as a light source, such as a combination of an LED and a light-receiving sensor, or a combination of a laser light-emitting element and a light-receiving sensor.
• a laser light-emitting element or LED as a light source
• Examples of light-receiving sensors include light-receiving sensors that receive reflected or transmitted light and perform photoelectric conversion. LEDs are used to measure blood flow in peripheral areas such as earlobes and fingertips, while laser light-emitting elements enable measurements in thicker body parts such as hands and feet, and provide more accurate values.
• the electrocardiogram signal detection means in the present invention can be a general electrocardiograph, such as an electrocardiograph that has two electrodes attached across the heart and an electrode as a ground, and obtains so-called QRS waves (waveforms representing ventricular excitation) from the potential detected by these electrodes.
• the electrodes may be attached by sticking them on the body, or may be configured to be used by touching the electrodes to the skin with the hand.
• examples of characteristic values obtained from an electrocardiogram signal and a blood flow pulse wave signal include, for example, time information from the R-wave peak phase to the peak value of the second derivative of the pulse wave (pulse wave propagation time), the pulse wave rise time (also called upstroke time) from the peak value of the second derivative of the pulse wave to the pulse wave peak, which is indicated as the force with which blood flow sent out from the heart pushes against blood vessels, and the time between one R wave and the next R wave (RR interval).
• examples of measured biosignals include systolic blood pressure, diastolic blood pressure, and other blood pressures measured by biosignal measurement means, such as existing sphygmomanometers, such as pressure-type blood pressure monitors, pulse wave transit time monitors, and tonometry-type blood pressure monitors.
• feature signals include one or more signals selected from pulse wave period signals, pulse wave amplitude values, pulse wave transit time, pulse wave rise time (Tu), R-R wave time signals, R wave amplitude, and QRS width.
• the feature signals are composed of the RR interval, pulse wave transit time, and pulse wave rise time (Tu) in the electrocardiogram waveform.
• the variable multipliers in this invention are numerical values such as integers and decimals, and examples include multiple numerical values that increase or decrease at regular intervals.
• SBP systolic blood pressure
• X is a patient-specific characteristic value
• C is the pulse wave transit time (msec)
• Tu is the pulse wave rise time (msec)
• RR is the RR interval (msec).
• the patient-specific characteristic value X can be obtained by dividing the systolic blood pressure value measured with an existing sphygmomanometer during initial setup before calculating the patient's estimated systolic blood pressure by the value obtained by substituting the Tu, C, and RR values measured at the same time into [(Tu/C) 0.5 /(0.82RR-0.15) 0.1 ].
• the patient-specific characteristic value X may be the average value X ave of the eigenvalues obtained by performing multiple measurements during initial setup.
• a systolic blood pressure value based on the systolic blood pressure value measured during initial setup can be constantly obtained from the eigenvalue X and the C, Tu, and RR values that change over time according to the above formula (1).
• equation (1) when mathematically optimizing equation (1), an optimization solver among the multiplier optimization methods is preferable. For example, as shown in equation (2), a multiplier is added to equation (1) and the multiplier value is determined by finding the smallest difference value between the actual measured value.
• Tu ave is the average pulse wave rise time (msec)
• C ave is the average pulse wave transit time (msec)
• RR ave is the average RR interval (msec). That is, Tu ave , C ave , and RR ave represent the average values of Tu, C, and RR extracted from a predetermined number of blood flow pulse waves.
• the characteristic value K is determined in the same manner as the characteristic value X.
• multipliers are used as variables and are represented by x(i), y(i), z(i), and a(i). Examples include a sequence type that lists different numerical values in an order, or a random number type.
• the variable multipliers in this invention may be any type used in mathematical optimization, and examples include multipliers in which appropriate numerical values are variable and assigned to each element of equation (1) used for optimization.
• Equations (2) and (3) above provide estimated blood pressure values.
• Optimization in this invention refers to the setting of a calculation algorithm with multipliers, coefficients, etc. that bring the calculated value and the actual measured value closer together.
• An example of optimization using multipliers in mathematical optimization is shown, for example, in Excel (registered trademark) Solver.
• Equation (3) is an equation in which the symbol i in equation (2) is replaced with the symbol (n, m), making it easier to explain.
• the symbol (n, m) indicates, for example, a state in which m variables are stored in each of n groups.
• the present invention simply involves substituting each determined parameter into equation (1), forming equation (2) or (3) based on equation (1) to apply a mathematical optimization algorithm or optimization solver algorithm, and determining the multiplier through multiplier optimization using, for example, Excel (registered trademark) solver (software included with the spreadsheet software Excel (registered trademark) (trademark)). It is sufficient if optimization can be performed based on biological information that provides actual measured values as reference values, such as arteriosclerosis calculation algorithms and blood flow calculation algorithms.
• the algorithms referred to in the present invention include, for example, equations (1) to (3), but also include any other equations that calculate biometric information, such as intermediate equations, or any combination of multiple equations.
• equations (1) to (3) show equations for obtaining an estimated systolic blood pressure value using blood flow information and electrocardiogram information, but the optimization method described in this invention can also be applied to other blood pressure calculation equations, blood flow calculation equations, and other equations that obtain biological information using an algorithm.
• the above algorithm is a calculation formula that estimates and calculates either the systolic blood pressure value or the amount of change therein, or both.
• the biological signal processing means comprises: extracting feature values from the electrocardiogram signal and the blood flow pulse wave signal to form an algorithm; a step of adding a variable multiplier to the algorithm, and calculating a difference between a value obtained by calculating the algorithm for each variable multiplier and an actual measurement value; and a step of determining a multiplier that minimizes the sum of squares of the difference values.
• the biological signal processing means for example, extracting feature values from the electrocardiogram signal and the blood flow pulse wave signal; Substituting the extracted feature values into an algorithm; applying a predetermined parameterized multiplier to the feature value in the algorithm; Substituting a predetermined value for a multiplier of the algorithm; a step of obtaining a difference between an output value of the algorithm into which the sequence values have been substituted and an actual measurement value; obtaining the sum of squares of the difference values; determining a multiplier when the difference value becomes a minimum value; and outputting an optimized biosignal value based on an algorithm formed by the determined multiplier.
• the program is stored in a storage medium connected to a web server, a cloud server, a personal computer, a single-board computer, etc., and is called from the storage medium and then executed on the computer.
• the present invention provides an optical blood flow measuring means for detecting a blood flow pulse wave from a living body; an electrocardiogram signal detection means for detecting an electrocardiogram signal from a living body; an actual blood pressure measurement means for measuring a target biological signal (e.g., a systolic (maximum) blood pressure value) to obtain an actual blood pressure value; a feature value calculation means for calculating feature values (such as the appearance time of an R wave in an electrocardiogram, a pulse wave rise time, and a pulse wave peak time) from the optical blood flow measurement means and the electrocardiogram signal detection means; and the following steps (i), (ii) and (iii): (i) a step of forming a sum of squares of values calculated by varying a multiplier of an algorithm (the following formula (2) or (3)) formed by adding a variable multiplier to a formula formed by the characteristic values; (ii) determining, as an optimal value, a multiplier that minimizes the difference between the sum of squares and the
• the present invention can obtain more accurate blood pressure estimates by optimizing the algorithm to create an optimization algorithm.
• mathematical optimization can be applied to obtain blood pressure-related values (such as systolic blood pressure) formed from pulse wave rise time (Tu), pulse wave propagation time, etc., obtained in relation to blood pressure estimation data.
• examples of possible implementations include a form in which the present invention is applied to a wearable device such as a wristwatch, or a display device that adjusts the time axis of items that can detect sudden changes in blood pressure when monitoring blood pressure and blood flow during blood purification such as hemodialysis without placing a burden on the patient.
• the actual measurement data that serves as the basis for optimization may be obtained only before measurement, or at certain intervals.
• an existing blood pressure monitor such as a cuff-type blood pressure monitor can be used, and this may be used as the reference value during the measurement period, once before and after the start of dialysis, or at regular intervals when the patient is restrained for nearly four hours, such as during dialysis treatment. In some cases, this may be only once at the beginning of dialysis treatment.
• Reference numeral 101 denotes an electrocardiogram input unit.
• the electrocardiogram input unit is, for example, composed of a plurality of electrodes and electrical lead wires connected to each electrode, and is used by attaching the electrodes in a state in which the heart is sandwiched between them.
• electrodes include a combination of conductive adhesive gel and electrical lead wires, as well as electrodes made of a conductive material that come into contact with fingers or hands.
• Reference number 102 is a photoelectric detection unit, consisting of an LED and a light-receiving element, or a laser light-emitting element and a light-receiving element, or both.
• Reference number 103 is an electrocardiogram detection unit, which is equipped with an analog noise filter and an analog amplifier, and generates an analog signal of at least a QRS wave. In addition to forming one lead from multiple electrode inputs, the electrocardiogram detection unit 103 may also form multiple different types of leads and generate an analog waveform for determining the average value of the fluctuating R-wave phase.
• Reference number 104 is a pulse wave input unit that receives the electrical signal obtained by the photoelectric detection unit 102 when laser light or LED light is irradiated through or reflected by a living body, and outputs the input electrical signal after electrically amplifying it. It may also have a noise filter.
• Reference number 105 is an AD converter for electrocardiograms that converts analog electrocardiogram signals into digital electrocardiogram signals and outputs them.
• Reference number 106 is an AD converter for blood flow pulse waves that converts the input analog blood flow pulse wave into a digital signal.
• Reference number 107 is an electrocardiogram filter that is formed from a digital filter and must pass at least the high frequency band required to detect QRS waves.
• the digital filter can be an existing algorithm, and in some cases, an analog filter can be used when computing power is insufficient.
• Reference number 108 denotes a blood flow pulse wave filter, formed from a digital filter, that can accurately obtain the amplitude and time of characteristic parts of the blood flow pulse wave after passing through the filter.
• the electrocardiogram filter 107 and blood flow pulse wave filter 108 may be incorporated into the arithmetic unit 109.
• Reference number 109 denotes the arithmetic unit, which has a computer processor including a digital signal processor (DSP) and a central processing unit (CPU), and memories such as random access memory (RAM) and read-only memory (ROM), and executes programs stored in the memory, calculates time intervals such as the RR interval, pulse wave rise time (Tu), and pulse wave propagation time, calculates amplitude values, stores and executes mathematical optimization algorithms, and outputs display signals.
• Reference number 110 denotes a memory unit, which temporarily or continuously stores the obtained optimized blood pressure-related information, pulse wave propagation time values, Tu values, etc.
• the storage unit 110 may be a solid state drive (SSD), hard disk (HD), RAM, or non-volatile memory with the capacity to record blood pressure-related value information for at least the duration of dialysis treatment (typically close to four hours), or it may be a device or system capable of storing information externally, such as on a cloud or server.
• SSD solid state drive
• HD hard disk
• RAM random access memory
• non-volatile memory with the capacity to record blood pressure-related value information for at least the duration of dialysis treatment (typically close to four hours)
• it may be a device or system capable of storing information externally, such as on a cloud or server.
• Reference numeral 111 denotes a blood pressure signal input unit.
• An example of a blood pressure signal input unit is a cuff that can be wrapped around the upper arm, wrist, etc. and inflated.
• Reference numeral 112 denotes a blood pressure measuring device. Examples of this blood pressure measuring device include existing pressure-type blood pressure measuring devices, as long as they are capable of measuring at least systolic blood pressure and outputting it as a digital value. If the blood pressure measuring device displays blood pressure values numerically, the blood pressure values can be manually input into the calculation unit 109. Alternatively, if the blood pressure measuring device has the function of outputting blood pressure value signals as digital data to the outside, the digital data can be automatically input into the calculation unit 109, which has the function of receiving this digital data.
• Reference numeral 113 denotes a display unit, which is composed of an LCD display and an LED array and can continuously display analog blood flow waveforms, optimized blood pressure (systolic blood pressure) information, pulse wave transit time, and Tu in real time.
• the display unit 113 may be integrated with the calculation unit 109, or it may be connected wirelessly or via a wire to a tablet terminal, smartphone terminal, or other personal computer (PC) terminal and display information on each LCD terminal. Furthermore, the display unit 113 can be configured to emit an alert (light, sound, etc.) when an unusual signal pattern occurs.
• the electrodes of the electrocardiogram input unit 101 are attached to the electrocardiogram measurement site on the living body, and the blood flow pulse wave sensor of the photoelectric detection unit 102 is attached to the fingertip, earlobe, or other site where blood flow pulse waves can be detected. Furthermore, the blood pressure measurement cuff that forms the blood pressure signal input unit 111 is wrapped around the upper arm.
• the blood pressure measuring device 112 is activated, and the maximum blood pressure (systolic blood pressure) and minimum blood pressure (diastolic blood pressure) values are obtained and temporarily stored in the memory unit 110, and measurement of the electrocardiogram and blood flow pulse wave begins.
• the electrocardiogram signal input from the electrocardiogram input unit 101 is detected by the electrocardiogram detection unit 103 for QRS wave detection, converted into a digital signal by the electrocardiogram AD converter 105, and output to the electrocardiogram filter 107.
• the blood flow pulse wave AD converter 106 AD converts the analog blood flow pulse wave signal into a digital blood flow pulse wave signal, which is output to the blood flow pulse wave filter 108.
• the blood flow pulse wave filter 108 performs filtering to extract the waveforms required to detect Tu (pulse wave rise time) and the end point of the pulse wave propagation time (PTT or C) on the blood flow pulse wave.
• an algorithm for calculating the pulse wave transit time, RR (the time width between peaks of the R wave on the electrocardiogram), etc. is calculated, an algorithm for obtaining predetermined target information is called, numerical values such as the pulse wave transit time are input, and the target values (e.g., estimated systolic blood pressure and estimated diastolic blood pressure) are calculated.
• the calculated target value is temporarily stored in the memory unit 110, and the algorithm is optimized to bring this value closer to the actually measured value.
• the multipliers that make up the algorithm are adjusted, an optimization algorithm is formed, and this is stored in the memory unit 110.
• the actual measured value is measured for the first time, it is measured as is, and a value that is closer to the target bio-information-related value based on the optimization algorithm is obtained.
• the obtained value is displayed on the LCD display of the display unit 113, and in some cases, it is displayed in parallel with other values, for example with the time axis compressed, so that it can be referenced by doctors, technicians, and nurses and used as a display to predict changes in blood pressure and detect other changes in physical condition.
• the calculation unit 109 will activate the blood pressure measuring device 112 again by activating a timer function or the like, obtain actual measurements, and obtain a more accurate, optimized target blood pressure-related value.
• the number of measurements required to obtain the optimized target biological value may be adjusted as appropriate, for example, during the dialysis treatment, only in the early stages, or at 1-hour, 30-minute, or 15-minute intervals.
• Reference number 201 is a start step, indicating, for example, a state in which preparations are complete to begin hemodialysis treatment and measurement.
• the electrocardiogram input unit 101 shown in Figure 1 which is equipped with electrodes for electrocardiogram measurement, is attached to the patient's body, and a photoelectric detection unit 102, such as a blood flow pulse wave sensor, is attached, for example, to a fingertip.
• a blood pressure measurement cuff which constitutes the blood pressure signal input unit 111 shown in Figure 1, is attached to the upper arm.
• Reference number 202 is a measurement start step that determines whether hemodialysis treatment has started; once measurement has started (yes), the process proceeds to a step in which actual blood pressure values are measured.
• Reference numeral 203 is the step of measuring the actual blood pressure value, inflating the cuff previously wrapped around the upper arm, and measuring blood pressure (e.g., systolic blood pressure). In this embodiment, since the purpose is to obtain an estimated blood pressure value, the reference blood pressure is measured using an existing method as the actual blood pressure value.
• Reference numeral 204 is the step of temporarily or continuously storing the actual blood pressure information, for example, storing individual actual blood pressure values when performing multiple blood pressure measurements to obtain an average blood pressure.
• Reference numeral 205 is the step of setting a comparative actual systolic blood pressure value, in which a systolic blood pressure value RSBPn is set among the actual blood pressure values.
• the systolic blood pressure value RSBPn may represent, for example, multiple systolic blood pressure values obtained by multiple (n) actual measurements, or a systolic blood pressure value obtained by a single actual measurement.
• Reference numeral 207 is a step for determining whether a comparative measured systolic blood pressure value RSBP for optimization has already been set. If it has already been set (yes), proceed to step 208. If it has not been set or if it will be set by periodic measurement (no), proceed to step 203 and measure the measured blood pressure value.
• Reference number 208 is a step in which the measured blood pressure value is replaced with the already set comparative measured systolic blood pressure value RSBP.
• Reference number 209 is a step in which the blood flow pulse wave and electrocardiogram signal are input, and the blood flow pulse wave and electrocardiogram signal shown in Figure 1 are converted from analog electrical signals obtained from the electrocardiogram input unit 101 and photoelectric detection unit 102 into digital signals.
• Reference number 210 is a filtering step, which is composed of a program routine for a known digital filter and is a step in which other noise information is removed to obtain the desired waveform information.
• Reference number 211 is a step for converting the data into blood flow pulse wave data and electrocardiogram data, for example, into a data string with a common time axis.
• Reference number 212 is a step for obtaining the RR interval, pulse wave rise time (Tu), and pulse wave propagation time (C) to be substituted into equation (3) from the blood flow pulse wave data and electrocardiogram data and temporarily storing them.
• Reference numeral 213 is a step of determining whether the average values can be calculated, performing repeated measurements to obtain the average values, and temporarily storing the results.
• Reference numeral 214 is a step of averaging a predetermined number of RR intervals, etc., to obtain average values RR ave , Tu ave , and C ave .
• reference number 215 is the step of setting variables (n, m) to be substituted for the multipliers a, x, y, and z.
• the variables (n, m) represent a configuration in which there are n groups (n1, n2, n3...nn), each containing m mutually different numerical values (m1, m2, m3...mm).
• Reference number 216 indicates the step of specifying the first group of the first group n.
• Reference number 217 indicates the state of specifying the first m value (m1) of the specified group.
• the variable m is just an example, and may be selected appropriately depending on the variable interval and the properties of the variable.
• Reference number 218 indicates an algorithm that combines a variable multiplier with equation (3), and is the step of finding the CSBPn,m value using the mth variable of the nth group as the multiplier.
• Reference number 219 is a step for calculating and temporarily storing the difference between CSBPn,m and the comparative measured systolic blood pressure value RSBP obtained by actual measurement.
• the measured value is the most recent measured value; the most recent may refer to a value measured at a preset time interval, or, if only the value measured at the start of measurement is used, the measured value at the start of measurement.
• Reference number 220 is a step for determining whether the mth value in the nth group is the last value (mm).
• Reference number 221 is a step for specifying the next mth value if the mth value is not the last.
• Reference number 222 is a step for calculating the sum of squares of m calculated difference values when the mth value in the nth group is the last value (mm). In this step, m difference value data for the nth group are temporarily stored.
• Reference number 223 is a step that determines whether the nth group is the last group.
• Reference number 224 is a step that specifies the (n+1)th group that follows the nth group.
• Reference number 225 is a step that determines the minimum sum of squares.
• the minimum value is determined from the calculated n sums of squares using the m numerical values of each group as multipliers, but if a target minimum value is set in advance, a numerical value close to that target value may be minimized, or the values for all n groups may not be calculated, and the value obtained when the CSBPn,m value changes very little along the way may be used.
• Reference number 226 is the step for determining the values of x, y, z, and a, and the corresponding x, y, z, and a values are found from the smallest CSBPn and m values.
• Reference number 225 is the end step, indicating the state when the routine shown in Figures 2 and 3 has ended, and constructs and outputs an algorithm that is now capable of calculating an optimized systolic blood pressure (SBP) value.
• SBP systolic blood pressure
• the device When starting hemodialysis treatment, the device is operated while preparations are made to attach electrodes for electrocardiograms, a sensor for measuring blood flow pulse waves, and a blood pressure measurement cuff to the upper arm (step 201).
• this embodiment is a routine for determining the algorithm for calculating estimated systolic blood pressure
• the systolic blood pressure estimation algorithm may already have been determined or actual blood pressure may have already been measured at the step 201 stage. Therefore, if actual blood pressure has already been measured and a comparative actual systolic blood pressure value RSBP has been determined (step 207), the previously set comparative actual systolic blood pressure value RSBP is used (step 208).
• the process proceeds to step 203, where the measured blood pressure value is measured.
• the blood pressure measuring device can be a conventional blood pressure monitor.
• the blood pressure monitor may be configured to automatically operate upon receiving a command signal from the calculation unit 109 and simultaneously starting measurement.
• the blood pressure values measured by the blood pressure monitor are temporarily stored in the memory unit 110 shown in FIG. 1 via the calculation unit 109 (step 204), and the systolic blood pressure value RSBPn is set from the temporarily stored blood pressure values (step 205).
• an average value is to be calculated from multiple systolic blood pressure values RSBPn, a predetermined number of systolic blood pressure values RSBPn are read in step 206, and the average value is used as the comparative measured systolic blood pressure value RSBP. If an average value is not required and the comparative measured systolic blood pressure value RSBP is set from a single measurement, one systolic blood pressure value RSBPn is used as the comparative measured systolic blood pressure value RSBP.
• the blood flow pulse wave and electrocardiogram signals are input via the electrocardiogram input unit 101 and photoelectric detection unit 102 shown in Figure 1 and converted to digital signals by the electrocardiogram AD converter 105 and blood flow pulse wave AD converter 106 (step 209).
• a digital filter extracts a signal with the required frequency band and noise removed (step 210).
• the blood flow pulse wave data and electrocardiogram data are then formed on the same time axis (step 211), and parameters such as RR, Tu, and C are calculated and temporarily stored (step 212). These parameters are obtained for each heartbeat, and are integrated over the number of heartbeats within a specified time interval (step 213) to calculate the average value (step 214).
• RR, Tu, and C are substituted into equation (3) to set multipliers for constructing an optimization algorithm (step 215).
• the multipliers added until a single value is determined are, for example, n groups, with m different values stored in each group. This grouping can also be done by dividing a string of numbers for a single multiplier by a fixed number.
• the nth group is specified (step 216).
• the first value m1 in this n1th group is specified (step 217), and this is substituted into the CSBPn,m formula to obtain a value (step 218).
• step 219 The difference between this value and the actual measured systolic blood pressure value RSBP for comparison is obtained (step 219).
• a determination is made as to whether this m value corresponds to the last value (step 220). If it is not the last (no), proceed to step 221, specify the next m value, and obtain the CSBPn,m value in step 218. If it is the last (yes), the average is taken for the difference values of n1 groups, and then the sum of squares DFS is obtained (step 222). In step 223, it is determined whether the group for which the sum of squares DFS was obtained is the last group. If it is not the last group (no), specify the next n+1th group (step 224), and proceed to step 217, where the first m value of the new n+1th group is assigned.
• step 225 the minimum DFS value is determined, and the multipliers (a, x, y, z) from equation (3) corresponding to the minimum value are determined (step 226). Upon this determination, the routine ends (step 227), and these multipliers are used to form an optimized equation (3) until the next actual blood pressure measurement.
• Example 11 Clinical experiment in hemodialysis treatment A cuff was attached to the upper arm of the hemodialysis patient to measure actual blood pressure, and electrocardiogram electrodes were attached to the right side of the chest, the left side of the chest, and the clavicle to measure electrocardiograms.Furthermore, to detect blood flow pulse wave signals, a sensor for a pulse wave meter or a laser blood flow meter was attached to the fingertip on the side where blood access was to be performed.
• the recorded data was filtered using a digital filter, and the heart rate (RR interval), pulse wave transit time (C), and pulse wave rise time (Tu) were extracted. Average values for these parameters were calculated over a specified time interval (30 seconds before and after the actual blood pressure measurement). The average value of the above analysis results within the time period during which the actual blood pressure was recorded using the cuff was calculated and substituted into equation (1).
• Equation (2) is formed by adding multipliers (a, x, y, z) to equation (1) based on the most recent actual blood pressure value, which is measured periodically.
• the multipliers (a, x, y, z) in equation (2) and performing mathematical optimization (for example, using Excel (registered trademark) Solver) that minimizes the difference from the actual measured value, the multipliers (a, x, y, z) are determined and an optimized SBP estimate is obtained.
• K is an individual value that further approximates the SBP value to the actual blood pressure value.
• Example 1 data is processed after dialysis treatment to obtain continuous systolic blood pressure data, but it is also possible to measure blood pressure fluctuations in real time using the optimization algorithms shown in Figures 2 and 3.
• Example 2 Measurement of Blood Pressure Changes Due to Exercise Load
• a healthy subject was systematically loaded with an electrocardiogram and blood flow pulse wave measurements for blood pressure estimation, and an estimated systolic blood pressure was calculated. More specifically, an electrocardiograph (on the left upper chest) and a blood flow meter or pulse wave meter sensor (on the earlobe) were attached to the exercising subject (healthy subject). Measurement of blood flow pulse wave and electrocardiogram was initiated, and blood pressure was measured using an upper arm cuff at the following times to obtain actual blood pressure values. Measurements were taken in the following order: normal ⁇ low exercise load ⁇ normal (2 times) ⁇ medium exercise load ⁇ normal (2 times) ⁇ high exercise load ⁇ normal (2 times), with the number of times shown in parentheses.
• Equation (2) or (3) was formed by adding multipliers (a, x, y, z) to equation (1) based on the most recent actual blood pressure values measured periodically. While varying the multipliers (a, x, y, z) for equation (2) or (3), mathematical optimization (using Excel (registered trademark) Solver, for example) was performed to minimize the difference from the actual measured value, thereby determining the multipliers (a, x, y, z) and obtaining an optimized SBP estimate. K is an individual value that further approximates the SBP estimate to the actual blood pressure value. K is a preset value that is specific to each subject.
• estimated blood pressure values can be calculated by converting the analog values of the electrocardiogram and blood flow pulse wave signals into digital values, calculating the R-R value, C value, and Tu value in real time, substituting these values into equation (2) or (3), and then determining an algorithm that determines the optimized multiplier from the calculation of the variable multiplier.
• Example 3 Measurement of blood pressure changes due to exercise load (alternately squatting and standing) in a healthy subject (male in his 30s)) Measurement of blood pressure changes due to exercise load in a healthy subject will be described with reference to Figure 6.
• 601 denotes the continuous biological information measurement device of the above embodiment
• 602 denotes a pulse wave input unit
• 603 denotes an electrocardiogram input unit.
• 602 and 603 correspond to 101 and 102, respectively, shown in Figure 1.
• 604 denotes a pulse wave sensor, which is formed with a light source and a light-receiving transistor in a reflective or transmissive configuration and is configured to be clamped and worn around the earlobe.
• 605 denotes an electrocardiogram electrode, consisting of one lead electrode. While the electrocardiogram electrode 605 is exemplified by a self-adhesive type, other fixing members such as a fixing belt may also be used.
• 606 denotes a comparative continuous blood pressure monitor. In this example, a Finapres blood pressure monitor (Finapress model 1 manufactured by Finapres Medical Systems BV) was used as the comparative measurement device.
• Reference numeral 607 denotes a fingertip sensor for the comparative continuous sphygmomanometer, which is composed of a cuff that is wrapped around a fingertip and inflates and deflates with air pressure, and a sensor that detects pressure pulse waves at the fingertip.
• the fingertip sensor for the comparative continuous sphygmomanometer 607 and the reference cuff-type sphygmomanometer 608 are conventional pressure cuff-type sphygmomanometers used for calibrating the continuous biological information measurement device 601 and the comparative continuous sphygmomanometer 606 of the above embodiment and for measuring reference blood pressure.
• Reference numeral 609 denotes an upper arm cuff, which may be an existing combination of a cuff that inflates and deflates with air pressure for blood pressure measurement connected to the pressure cuff-type sphygmomanometer 608 and a sensor.
• the upper arm cuff may also be used to calibrate the blood pressure values calculated by the comparative continuous sphygmomanometer 606.
• Reference numeral 610 denotes a chair on which the subject 6M sits when calibrating the continuous biological information measurement device 601 and the comparative continuous sphygmomanometer of the above embodiment, or on which the subject 6M sits during a low-temperature stress experiment.
• reference numeral 611 denotes a cold water container, which is large enough to put your hand in and contains cold water at a temperature suitable for the load.
• an electrocardiogram electrode 605 connected to a one-lead electrocardiogram input unit 603 was attached to the upper left chest, and a counter electrode (not shown) was attached to the abdomen.
• a pulse wave sensor 604 connected to a pulse wave input unit 602 was attached by clamping it to the left earlobe.
• the upper arm cuff 609 of the reference cuff-type sphygmomanometer 608 was attached to the right upper arm.
• the cuff of the fingertip sensor 607 for the comparative continuous sphygmomanometer of the existing comparative continuous sphygmomanometer 606 was attached to the fingertip.
• Blood pressure measurement was started using the biological information continuous measurement device 601 of the above embodiment, the comparative continuous sphygmomanometer 606, and the cuff-type sphygmomanometer 608. Blood pressure measurements using the cuff-type blood pressure monitor 608 were taken in the following order: normal (2 times) ⁇ squatting (high load) (1 time) ⁇ normal (2 times) ⁇ squatting (high load) (1 time) ⁇ normal (3 times), for a number of times equal to or greater than the number shown in parentheses. 2. Blood pressure information was measured using the continuous biological information measuring device 601, and the blood pressure ratio was calculated. Continuous blood pressure values were obtained using the comparative continuous blood pressure monitor 606, and actual blood pressure values were obtained using the cuff-type blood pressure monitor 608, and these were compared.
• the blood pressure (SBP) estimated value obtained by the biological information continuous measurement device 601 of the above embodiment was found to track the intermittent blood pressure value obtained by the cuff-type blood pressure monitor 608 and the continuous blood pressure value obtained by the comparative continuous blood pressure monitor 606, with respect to the changing blood pressure value. Furthermore, as a comparative example, it was found that the blood pressure estimated value also roughly matched the blood pressure estimated value obtained by the comparative continuous blood pressure monitor 606.
• Example 4 Measurement of blood pressure changes due to low temperature load in a healthy subject (male in his 30s)
• the blood pressure monitor was attached according to steps 1 and 2 above.
• Blood pressure measurement was started using the biological information continuous measurement device 601 of the above embodiment, the comparative continuous sphygmomanometer 606, and the cuff-type sphygmomanometer 608. Measurements using the cuff-type blood pressure monitor 608 were taken in the following order: normal time (twice) ⁇ immersing the hand opposite the upper arm cuff 609 in ice water in the cold water container 611 (for approximately 60 to 90 seconds) (once) as shown in Figure 6(b) ⁇ normal time (three times) ⁇ immersing the hand opposite the upper arm cuff 609 in ice water in the cold water container 611 (for approximately 60 to 90 seconds) (once) ⁇ normal time (three times), with the number of measurements shown in parentheses being at least. 2. Using the above formula (2), the calculated blood pressure ratio was compared with the actual blood pressure measured by the comparison continuous blood pressure monitor 606 and the cuff-type blood pressure monitor 608.
• the present invention can measure continuous systolic blood pressure values without invasive procedures such as pressurization, making it possible to use more wearable biometric detection devices in treatments such as hemodialysis, where blood is extracted from the body for blood purification and then returned to the body after purification.
• Electrocardiogram input unit 101
• Photoelectric detection unit 103
• Electrocardiogram detection unit 104
• Pulse wave input unit 105
• AD converter for electrocardiogram 106
• AD converter for blood flow pulse wave 107
• Electrocardiogram Filter 108
• Blood flow pulse wave filter 109
• storage unit 111
• Blood pressure signal input unit 112
• Blood pressure measuring device 601
• Biological information continuous measuring device 602
• Electrocardiogram electrode 606 Comparison continuous blood pressure monitor 607 Fingertip sensor for comparison continuous blood pressure monitor 608
• Reference cuff type blood pressure monitor 609 Upper arm cuff

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