JP5620001B2 - Blood pressure reduction prediction device - Google Patents

Description

  The present invention relates to a technical field of a blood pressure decrease prediction device that predicts blood pressure decrease in a living body.

  In artificial dialysis, the blood pressure of a patient may decrease due to, for example, a decrease in circulating blood volume due to water removal. If blood pressure decreases, the patient may be in a shock state, and blood pressure reduction during artificial dialysis is not a favorable situation. Thus, for example, Patent Documents 1 and 2 propose a technique for quickly determining a decrease in blood pressure of a patient during artificial dialysis. Patent Document 1 discloses a technique of predicting a change in blood pressure by weighted evaluation of blood pressure change-related information and controlling the rate of water removal in artificial dialysis based on the prediction result. Further, in Patent Document 2, in a time zone in which there is a high risk that the blood pressure of a patient during a dialysis period is low, an abnormality determination value for determining a decrease in blood pressure as abnormal is set to be smaller than other time zones. Has disclosed a technique that makes it easy to determine an abnormality in blood pressure in a time zone during which the blood pressure tends to decrease.

JP 2003-10319 A JP 2002-369882 A

  However, in the technique disclosed in Patent Document 1 described above, since a decrease in blood pressure is determined using a single evaluation formula from the start to the end of dialysis, there is a technical problem that determination accuracy is lowered. . Further, since the total value of the fluctuation values of the plurality of parameters is viewed, the influence of the sharp change of the specific parameter on the determination result is limited.

  Further, in the technique disclosed in Patent Document 2 described above, since the abnormality determination value varies depending on the person to be measured, there arises a technical problem that it is necessary to obtain an individual abnormality determination value in advance by prior measurement. Furthermore, the likelihood of blood pressure reduction may vary depending on physical condition or the like even in the same patient. Therefore, when the physical condition is unexperienced in the past, the reliability of the abnormality determination value that predicts a decrease in blood pressure is reduced, resulting in a technical problem that a decrease in blood pressure cannot be accurately determined.

  The present invention has been made in view of the above-described problems, for example, and provides, for example, a blood pressure decrease prediction device that can predict a decrease in blood pressure of a living body at an early stage and with high accuracy, while placing little burden on the living body. Is an issue.

In order to solve the above-described problem, the blood pressure decrease prediction device of the present invention is a blood pressure decrease prediction device that predicts blood pressure decrease in a living body, and a pulse rate calculation unit that calculates the pulse rate of the living body, and the blood flow rate of the living body A blood flow rate calculation unit that calculates a risk level, and a risk level determination unit that determines a risk level indicating a risk of blood pressure reduction based on fluctuations in at least one of the calculated pulse rate and the calculated blood flow rate The risk that the blood pressure lowers when the fluctuation width of at least one of the calculated pulse rate and the calculated blood flow volume in a predetermined period exceeds a threshold determined according to the determined risk level but a determining risk level high determination section that the high risk level high state than the determined risk level, the risk level high determination unit was the calculated Compared to the case where the fluctuation range of either the heart rate or the calculated blood flow exceeds a threshold value determined according to the determined risk level, the calculated pulse rate and the calculated blood flow When both fluctuation ranges exceed a threshold value determined according to the determined risk level, it is determined that the risk level is high in which the risk of blood pressure reduction is high .

  The effect | action and other gain of this invention are clarified from the form for implementing invention demonstrated below.

It is a block diagram which shows the structure of the blood-pressure fall prediction apparatus which concerns on a present Example. It is a graph for demonstrating an example of the calculation method of a pulse rate, a blood flow rate, and a pulse wave amplitude based on a blood flow waveform. It is a flowchart which shows the flow of a blood pressure fall prediction process. It is a flowchart which shows the flow of a process in the fluctuation | variation detection subroutine of a pulse rate. It is a flowchart which shows the flow of a process in the fluctuation | variation detection subroutine of a blood flow rate. It is a flowchart which shows the flow of a process in the fluctuation | variation detection subroutine of a pulse wave amplitude. It is a conceptual diagram which shows notionally an example of the fluctuation | variation pattern table regarding a pulse rate. It is a conceptual diagram which shows notionally an example of the fluctuation | variation pattern table regarding a blood flow rate. It is a conceptual diagram which shows notionally an example of the fluctuation | variation pattern table regarding the combination of a pulse rate and a blood flow rate. It is a conceptual diagram which shows notionally an example of the fluctuation pattern table regarding a pulse rate, a blood flow rate, and a pulse wave amplitude. It is a flowchart which shows the flow of a risk level high determination process.

  Hereinafter, embodiments of the present invention will be described.

  In order to solve the above-described problem, the blood pressure decrease prediction device according to the present embodiment is a blood pressure decrease prediction device that predicts a blood pressure decrease of a living body, and a pulse rate calculation unit that calculates the pulse rate of the living body; A blood flow rate calculation unit that calculates a blood flow rate, and a risk level determination that determines a risk level indicating a risk that the blood pressure decrease occurs based on at least one variation of the calculated pulse rate and the calculated blood flow rate And the calculated pulse rate and / or the calculated blood flow volume during a predetermined period exceeds a threshold determined according to the determined risk level, the blood pressure decrease occurs A risk level high determination unit that determines that the risk to be performed is in a risk level high state that is higher than the determined risk level.

  During the operation of the blood pressure decrease prediction device according to the present embodiment, first, the pulse rate of the living body is calculated by the pulse rate calculating unit, and the blood flow rate of the living body is calculated by the blood flow rate calculating unit. The pulse rate calculating unit and the blood flow rate calculating unit may calculate the pulse rate and the blood flow rate using separate measuring devices, or may calculate the pulse rate and the blood flow rate using the same measuring device. . For example, when using separate measuring devices, an electrocardiograph can be used to calculate the pulse rate, and a blood flow meter can be used to obtain the blood flow. On the other hand, when using the same measuring device, it is possible to calculate the pulse rate and the blood flow rate using only a blood flow meter, for example. More specifically, for example, a blood flow waveform of a living body that is a subject or a patient (that is, a waveform signal indicating a change in blood flow over time) is input from a laser blood flow meter using a laser Doppler flowmetry method, for example. Based on the input blood flow waveform, the pulse rate and blood flow rate of the living body are calculated by the pulse rate calculation unit and the blood flow rate calculation unit, respectively. The pulse rate calculation unit typically calculates the frequency corresponding to the pulse wave of the blood flow waveform (that is, the reciprocal of the cycle) as the pulse rate. The blood flow rate calculation unit typically calculates an average value of a blood flow waveform for a predetermined time as a blood flow rate.

  In the present embodiment, in particular, the risk level determination unit indicates the risk of a decrease in blood pressure in the living body (that is, the possibility that a decrease in blood pressure will occur) based on fluctuations in at least one of the calculated pulse rate and blood flow. Risk level is determined. The risk level determination unit determines the risk level by referring to a predetermined risk level determination table in which, for example, a combination of fluctuations in pulse rate and blood flow rate is associated with a risk level.

  The risk level determination unit may determine the risk level using one of the calculated pulse rate and blood flow, or may determine the risk level using both the calculated pulse rate and blood flow. Also good. However, compared to the case where the risk level is determined using either one of the calculated pulse rate or blood flow, the case where the risk level is determined using both the calculated pulse rate and blood flow, The risk level can be determined with higher accuracy.

  Specifically, the risk level determination unit determines that the risk level is “low” when, for example, the pulse rate is increasing or the blood flow volume is decreasing, and the pulse rate becomes constant after the increase. The risk level is determined to be “medium” when the blood flow rate becomes constant after the decrease, and when either the pulse rate or the blood flow rate becomes constant after the decrease and further decreases, the risk level becomes “ It is determined to be “high”. Or a risk level determination part determines a risk level using the risk level determination table etc. in which the value of the risk level was stored so as to respond | correspond to the combination of the fluctuation | variation of a pulse rate and a blood flow rate. In this way, the risk level determination unit can determine the risk level more accurately according to changes in both the pulse rate and the blood flow. The risk level determination unit may determine the risk level using other parameters (for example, pulse wave amplitude, etc.) in addition to the pulse rate and blood flow volume.

  Here, blood pressure is determined by the product of cardiac output and peripheral vascular resistance. “Cardiac output” is the amount of blood that is pumped (ie, pumped out) from the heart in one minute, and changes according to the heart rate that changes depending on the function of the autonomic nervous system (sympathetic / parasympathetic nervous system). To do. The cardiac output is determined by the product of a single cardiac output and a heart rate that are output from the heart in a single heartbeat. Thus, blood pressure is determined by the product of heart rate, stroke output and peripheral vascular resistance. “Peripheral vascular resistance” refers to difficulty in blood flow in peripheral arteries, and changes depending on the action of the autonomic nervous system (particularly the sympathetic nervous system). When the living body is a healthy person, the living body usually adjusts the heart rate and peripheral vascular resistance in order to maintain blood pressure. In other words, when the blood pressure is about to drop, the living body maintains the blood pressure by adjusting the heart rate and peripheral vascular resistance. Therefore, the heart rate and peripheral vascular resistance often change before the blood pressure rapidly decreases.

  As described above, the risk level determination unit determines the risk level of blood pressure reduction in the living body based on at least one change in the calculated pulse rate and blood flow rate. Here, it is estimated that the pulse rate corresponds to the heart rate, and the blood flow volume often varies according to the variation of the peripheral vascular resistance. Therefore, according to the risk level determination unit, it is possible to appropriately determine the risk level indicating the risk of blood pressure reduction based on the fluctuation of at least one of the pulse rate and the blood flow rate.

  In the present embodiment, in addition to the determination of the risk level described above, the risk level high determination unit determines whether or not the risk level is high. Specifically, the risk level high determination unit, when the fluctuation range in the predetermined period of at least one of the calculated pulse rate and the calculated blood flow exceeds a threshold determined according to the determined risk level. It is determined that the risk level is higher than the determined risk level. Here, the “predetermined period” is a period set for detecting fluctuations in the pulse rate and blood flow in a relatively short period, and the risk level determination unit detects fluctuations in the pulse rate and blood flow. It is set shorter than the period to do. The “threshold value determined according to the determined risk level” is a threshold value determined according to the level of the risk level determined by the risk level determination unit, and is determined as a lower value as the risk level is higher. The In other words, the higher the risk level determined by the risk level determination unit, the easier it is to determine that the risk level is high.

  The risk level high determination unit may determine whether or not the risk level is high using either one of the calculated pulse rate and blood flow volume, and calculates both the calculated pulse rate and blood flow volume. It may be used to determine whether the risk level is high. However, compared to the case where it is determined whether or not the risk level is high using either one of the calculated pulse rate or blood flow volume, the risk level high using both the calculated pulse rate and blood flow volume. In the case of determining whether or not the state is the state, it is possible to determine whether or not the risk level is in the high state with higher accuracy.

  In addition, when one of pulse rate and blood flow volume is used to determine the risk level, in determining whether the risk level is high, the other one that is different from the one used for determining the risk level is used. It may be used. That is, when the risk level determination unit determines the risk level using the calculated pulse rate, the risk level high determination unit determines whether the risk level is high using the calculated blood flow rate Also good. Similarly, when the risk level is determined using the calculated blood flow volume, the risk level high determination unit determines whether the risk level is high using the calculated pulse rate. May be.

  According to the study of the present inventor, when the pulse rate and blood flow volume fluctuate rapidly in a short period, the risk level of blood pressure decrease is considered to increase, but the degree of the increase was determined by the risk level determination unit It has been found that it corresponds to the risk level. For example, when the pulse rate and the blood flow rate fluctuate rapidly in a short period in a state where the risk level is relatively high, the risk level for lowering blood pressure rises relatively large. On the other hand, when the pulse rate and the blood flow volume fluctuate rapidly in a short period in a state where the risk level is relatively low, the risk level for lowering blood pressure rises relatively small.

  As described above, the risk level is determined only by the risk level determination unit by determining whether or not the risk level is in a high state by using the fluctuation in either one of the calculated pulse rate and blood flow for a predetermined period. Compared with the case where it does, the risk that a blood-pressure fall will generate | occur | produce with high precision can be estimated.

  In the present embodiment, the risk level determined by the risk level determination unit or the risk level high state determined by the risk level high determination unit is externally displayed as a color, number, character, sentence, figure, symbol, sound, or the like. By outputting, it is possible to inform the living body that is the subject or the patient, or a person concerned such as a doctor or a nurse about the risk of lowering blood pressure. As a result, it is possible to reduce or prevent delaying treatment for a living body that is predicted to decrease in blood pressure (that is, it is possible to perform treatment early on a living body that is at risk of blood pressure reduction).

  Note that the risk level and the risk level high state are not simply output as described above, but may be used for control of other connected devices. For example, when the living body being a patient is performing artificial dialysis, the risk of blood pressure or lower can be suitably reduced by controlling the operation of the dialysis machine based on the risk level and the high level of the risk level. It becomes. Further, when another device such as a dialysis device is connected, it is also possible to output a risk level and a risk level high state reflecting information of the other device. For example, if a signal for calculating a pulse rate and a blood flow value which are parameters for determining a risk level is received, but dialysis is not actually performed, dialysis is not performed from a dialysis machine. It is also possible to perform control such that the risk level and the risk level high state are not output after receiving the information.

  Further, in the present embodiment, since the pulse rate and the blood flow are calculated based on the blood flow waveform input from the laser blood flow meter, for example, compared with the case where the blood pressure is measured using a cuff or an electrode, for example. There is an advantageous effect that little or no burden is imposed on the living body.

  As described above, according to the blood pressure decrease prediction device of the present embodiment, it is possible to predict a decrease in blood pressure of a living body at an early stage and with high accuracy without imposing a burden on the living body.

  In one aspect of the blood pressure decrease prediction device according to the present embodiment, the risk level high determination unit determines whether the fluctuation range of any one of the calculated pulse rate and the calculated blood flow volume is the determined risk level. Compared with the case where the threshold value determined according to the above is exceeded, the fluctuation range of both the calculated pulse rate and the calculated blood flow rate exceeds the threshold value determined according to the determined risk level. It is determined that the risk level is in a high state where the risk of blood pressure reduction is high.

  In this aspect, when the fluctuation range of any one of the calculated pulse rate and the calculated blood flow exceeds a threshold value determined according to the determined risk level, the risk of blood pressure reduction is in a high risk level state. Among these, it is determined that the state is relatively low (hereinafter referred to as “risk level high A state” as appropriate).

  On the other hand, if the fluctuation range of both the calculated pulse rate and the calculated blood flow exceeds the threshold determined according to the determined risk level, the risk of blood pressure drop is compared even in the high risk level state It is determined that the risk level is high (hereinafter referred to as “risk level high B state” as appropriate).

  As described above, the risk of blood pressure reduction is determined to be the risk level high A state or the risk level high B state depending on which parameter of the calculated pulse rate and the calculated blood flow volume exceeds the threshold value. By doing so, the risk of lowering blood pressure can be predicted with higher accuracy.

  In another aspect of the blood pressure decrease prediction device according to the present embodiment, the risk level determination unit determines a predetermined risk level in which at least one of the pulse rate and the blood flow is associated with the risk level. The risk level may be determined by referring to a table.

  According to this aspect, the risk level determination unit determines the risk level indicating the risk of blood pressure reduction by referring to the predetermined risk level determination table. The risk level determination table is a predetermined reference table for determining a risk level, in which at least one variation in pulse rate and blood flow rate is stored in association with a risk level when the variation occurs. Look-up table).

  For example, a risk level value is stored in the risk level determination table so as to correspond to a fluctuation value of at least one of the pulse rate and the blood flow rate. Specifically, the risk level determination table stores “low” as the risk level when the pulse rate is rising or when the blood flow rate is decreasing, and the pulse rate is constant after the rise. Is stored as the risk level corresponding to when the blood flow rate becomes constant after falling, and when either the pulse rate or blood flow rate becomes constant after falling and further falls “High” is stored as the corresponding risk level.

  Alternatively, risk level values are stored in the risk level determination table so as to correspond to combinations of fluctuations in pulse rate and blood flow. Specifically, “LV1” is stored as the risk level when the pulse rate increases and the blood flow rate is constant. “LV1” is stored as the risk level when the pulse rate is constant and the blood flow rate is decreasing. As the risk level when the pulse rate is increasing and the blood flow volume is decreasing, “LV2” indicating that the risk of lowering blood pressure is higher than “LV1” is stored. As the risk level when the pulse rate is constant after the increase and the blood flow rate is decreasing, “LV3” indicating that the risk of blood pressure reduction is higher than “LV2” is stored. “LV3” is stored as the risk level when the pulse rate is increasing and the blood flow is constant after the decrease. As the risk level when the pulse rate is constant after the increase and the blood flow rate is constant after the decrease, “LV4” indicating that there is a higher risk of blood pressure reduction than “LV3” is stored. “LV5” is stored as a risk level when the pulse rate becomes constant after the rise and further falls, and the blood flow rate is constant after the decrease, indicating that the risk of lowering blood pressure is higher than “LV4”. Yes. “LV5” is stored as the risk level when the pulse rate is constant after the increase and the blood flow is constant after the decrease and further decreases. “LV6” indicating that the risk level is higher than “LV5” as the risk level when the pulse rate is constant and further decreased after the increase, and the blood flow is constant and further decreased after the decrease. Is stored.

  The risk level determination table may store risk level values so as to correspond to combinations of fluctuations in pulse rate and blood flow volume and other parameters (for example, pulse wave amplitude).

  By the way, the risk level determination table can be created by estimating the risk of blood pressure decrease when the pulse rate and the blood flow volume fluctuate in advance experimentally, empirically, or by simulation.

  When the calculated pulse rate and blood flow fluctuation value match one of the pulse rate and blood flow fluctuation values stored in the risk level determination table, the risk level determination unit sets the risk level to the matched combination. The risk level associated with is determined. If the calculated pulse rate and blood flow fluctuation value do not match either the pulse rate or blood flow fluctuation value stored in the risk level determination table, for example, the risk level is almost free of risk. Alternatively, it may be determined as “no” indicating extremely low.

  In this aspect, the risk level can be determined relatively easily and accurately by using the risk level determination table. Therefore, it is possible to predict a decrease in blood pressure of the living body more appropriately, and it is possible to more appropriately determine a risk level indicating a risk that a decrease in blood pressure occurs.

  In another aspect of the blood pressure decrease prediction device according to the present embodiment, the pulse rate calculation unit calculates the pulse rate of the living body based on a blood flow waveform indicating a change in blood flow of the living body over time, The blood flow rate calculation unit calculates the blood flow rate of the living body based on the blood flow waveform.

  According to this aspect, each of the pulse rate and the blood flow rate of the living body is calculated from the blood flow waveform indicating the change with time of the blood flow rate of the living body. That is, the pulse rate and blood flow rate of the living body are not calculated based on different parameters, but are calculated from the same parameters.

  In this aspect, for example, from the blood flow waveform obtained from a blood flow meter or the like, two types of parameters, ie, the pulse rate and blood flow rate of the living body used for determining the risk level and determining whether or not the risk level is high are calculated can do. Therefore, it is possible to simplify the apparatus configuration and the calculation process of each parameter.

  In another aspect of the blood pressure decrease prediction device according to the present embodiment, the blood pressure decrease prediction apparatus further includes a pulse wave amplitude calculation unit that calculates the pulse wave amplitude of the living body, and the risk level determination unit calculates the calculated pulse rate and the calculated pulse rate. In addition to at least one of the blood flow rates, a risk level indicating a risk of the blood pressure decrease is determined based on the calculated fluctuation of the pulse wave amplitude.

  According to this aspect, the risk level determination unit predicts a decrease in blood pressure in the living body based on the fluctuation in the calculated pulse wave amplitude in addition to the fluctuation in at least one of the calculated pulse rate and blood flow volume. The blood pressure drop in the living body can be predicted earlier and more appropriately.

  In the aspect including the pulse wave amplitude calculation unit described above, the risk level determination unit associates at least one of the pulse rate and the blood flow rate, and a combination of each variation of the pulse wave amplitude with the risk level. The risk level may be determined by referring to the predetermined risk level determination table.

  In this case, the risk level determination unit determines a risk level indicating a risk of blood pressure reduction by referring to a predetermined risk level determination table. The risk level determination table stores a risk level in which a combination of fluctuations in at least one of pulse rate and blood flow volume and fluctuations in pulse wave amplitude and a risk level when the combination occurs are stored in association with each other in advance. It is a predetermined reference table (lookup table) for determination.

  For example, in the risk level determination table, “LV1” is stored as a risk level when the pulse rate is constant, the pulse wave amplitude is reduced, and the blood flow is constant. As the risk level when the pulse rate is rising, the pulse wave amplitude is decreasing, and the blood flow is constant, “LV2” indicating that the risk of blood pressure drop is higher than “LV1” is stored. Has been. “LV2” is stored as the risk level when the pulse rate is constant, the pulse wave amplitude is decreasing, and the blood flow volume is decreasing. As the risk level when the pulse rate is increasing, the pulse wave amplitude is decreasing, and the blood flow volume is decreasing, “LV3” indicating that the risk of blood pressure decrease is higher than “LV2”. Stored. “LV4” indicating that the risk level is higher than “LV3” as the risk level when the pulse rate is constant after the pulse rate is increased, the pulse wave amplitude is decreased, and the blood flow volume is decreased. Is stored. “LV4” is stored as the risk level when the pulse rate is rising, the pulse wave amplitude is decreasing, and the blood flow is constant after the decrease. “LV5” indicates that the risk level is higher than “LV4” as the risk level when the pulse rate is constant after the increase, the pulse wave amplitude is decreased, and the blood flow is constant after the decrease. Is stored. As the risk level when the pulse rate is constant and further decreased after the increase, the pulse wave amplitude is decreasing and the blood flow is constant after the decrease, the risk of lowering blood pressure is higher than “LV5” “LV6” is stored. “LV6” is stored as the risk level when the pulse rate is constant after the increase, the pulse wave amplitude is decreasing, and the blood flow is constant after the decrease and further decreases. As the risk level when the pulse rate is constant and further decreased after rising, the pulse wave amplitude is decreasing and the blood flow rate is constant and further decreased after the decrease, blood pressure lowers than "LV6". “LV7” indicating that the risk is high is stored.

  In the risk level determination unit, the calculated combination of the pulse rate, the blood flow volume, and the fluctuation of the pulse wave amplitude matches any of the combination of the pulse rate, the blood flow volume, and the fluctuation of the pulse wave amplitude stored in the risk level determination table. In this case, the risk level is determined to be a risk level associated with the matched combination. If the calculated pulse rate, blood flow volume and pulse wave amplitude variation combination does not match any of the pulse rate, blood flow volume and pulse wave amplitude variation combinations stored in the risk level determination table, For example, the risk level may be determined as “none” indicating that there is almost no risk or very low risk.

  In this aspect, the risk level can be determined relatively easily and accurately by using the risk level determination table. Therefore, it is possible to predict a decrease in blood pressure of the living body more appropriately, and it is possible to more appropriately determine a risk level indicating a risk that a decrease in blood pressure occurs.

  In the aspect including the pulse wave amplitude calculation unit described above, the pulse rate calculation unit calculates the pulse rate of the living body based on a blood flow waveform indicating a change in blood flow of the living body over time, and the blood flow rate The calculation unit calculates the blood flow volume of the living body based on the blood flow waveform, and the pulse wave amplitude calculation unit calculates the pulse wave amplitude of the living body based on the blood flow waveform. Good.

  In this case, each of the pulse rate, the blood flow volume, and the pulse wave amplitude of the living body is calculated from a blood flow waveform that indicates a change over time in the blood flow volume of the living body. That is, the pulse rate, blood flow rate, and pulse wave amplitude of the living body are not calculated based on mutually different parameters, but are calculated from the same parameters.

  In this aspect, for example, from the blood flow waveform obtained from a blood flow meter or the like, there are three types of pulse rate, blood flow rate, and pulse wave amplitude of the living body used for determining the risk level and determining whether or not the risk level is in the high state. All parameters can be calculated. Therefore, it is possible to simplify the apparatus configuration and the calculation process of each parameter.

  In another aspect of the blood pressure decrease prediction device according to the present embodiment, the blood pressure reduction prediction apparatus further includes a first output unit that outputs the risk level determined by the risk level determination unit to the outside.

  According to this aspect, the output unit outputs the risk level determined by the risk level determination unit to the outside, for example, as a color, number, character, sentence, figure, symbol, sound, or the like. Therefore, it is possible to notify the subject who is a subject or patient, or a related person such as a doctor or a nurse about the risk of blood pressure reduction. As a result, it is possible to reduce or prevent delaying treatment for a living body that is predicted to decrease in blood pressure (that is, it is possible to perform treatment early on a living body that is at risk of blood pressure reduction).

  In another aspect of the blood pressure decrease prediction device according to the present embodiment, the blood pressure decrease prediction apparatus further includes a second output unit that outputs the risk level high state determined by the risk level high determination unit to the outside.

  According to this aspect, the output unit displays the determination result (that is, whether the risk level is high or not) by the risk level high determination unit as, for example, a color, a number, a character, a sentence, a figure, a symbol, or a sound. Output to the outside. Therefore, it is possible to notify the subject who is a subject or patient, or a related person such as a doctor or a nurse about the risk of blood pressure reduction. As a result, it is possible to reduce or prevent delaying treatment for a living body that is predicted to decrease in blood pressure (that is, it is possible to perform treatment early on a living body that is at risk of blood pressure reduction).

  Such an operation and other gains in this embodiment will be further clarified from examples described below.

  Embodiments of the present invention will be described below with reference to the drawings.

<Device configuration>
First, the configuration of the blood pressure decrease prediction apparatus according to the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram illustrating the configuration of the blood pressure decrease prediction apparatus according to the present embodiment.

  In FIG. 1, a blood pressure decrease prediction apparatus 100 according to the present embodiment is an apparatus for predicting a decrease in blood pressure of the living body 900 while the living body 900 as a patient is undergoing artificial dialysis by the dialysis apparatus 600. The blood pressure decrease prediction device 100 includes a pulse rate calculation unit 110, a blood flow rate calculation unit 120, a pulse wave amplitude calculation unit 130, a blood pressure decrease prediction unit 140 having a risk level determination unit 150 and a risk level high determination unit 160, And an output unit 170.

  The blood pressure decrease prediction device 100 is configured such that the blood flow waveform output from the blood flow waveform output device 800 is input. The blood flow waveform output device 800 is a laser blood flow meter using, for example, a laser Doppler flowmetry method, and outputs a blood flow waveform of the living body 900 (that is, a waveform signal indicating a change in blood flow over time).

  The pulse rate calculation unit 110, the blood flow rate calculation unit 120, and the pulse wave amplitude calculation unit 130 calculate the pulse rate, the blood flow rate, and the pulse wave amplitude of the living body 900 based on the blood flow waveform input from the blood flow waveform output device 800. Calculate each.

  The risk level determination unit 150 uses the pulse rate, blood flow rate, and pulse wave amplitude fluctuations of the living body 900 calculated by the pulse rate calculation unit 110, the blood flow rate calculation unit 120, and the pulse wave amplitude calculation unit 130, respectively. A risk level indicating a risk of a decrease in blood pressure of the living body 900 is determined.

  The risk level determination unit calculates fluctuations of the pulse rate, blood flow rate, and pulse wave amplitude of the living body 900 in a short period calculated by each of the pulse rate calculation unit 110, the blood flow rate calculation unit 120, and the pulse wave amplitude calculation unit 130. It is used to determine whether or not the risk level of the living body 900 being lowered is very high.

  The output unit 170 outputs the risk level determined by the risk level determination unit 150 and the determination result of the risk level high determination unit 160 (that is, whether or not the risk level is high) to the monitor.

  The control unit 180 controls the operation of the dialysis apparatus 600 according to the risk level determined by the risk level determination unit 150 and the determination result of the risk level high determination unit 160. The control unit 180 is also configured to receive various information (for example, the operation status of the dialysis machine, various parameters during dialysis, etc.) from the dialysis machine 600.

<Parameter calculation process>
Next, a specific calculation method of the pulse rate, blood flow rate, and pulse wave amplitude in the pulse rate calculation unit 110, the blood flow rate calculation unit 120, and the pulse wave amplitude calculation unit 130 will be described with reference to FIG. FIG. 2 is a graph for explaining an example of a method for calculating the pulse rate, the blood flow volume, and the pulse wave amplitude based on the blood flow waveform. FIG. 2 shows an example of a blood flow waveform output from the blood flow waveform output device 800.

  In FIG. 2, the pulse rate calculation unit 110 calculates the frequency of the waveform corresponding to the pulse wave in the blood flow waveform, that is, the reciprocal (1 / A) of the period A of the blood flow waveform as the pulse rate. The pulse rate may be calculated by using another calculation method such as fast Fourier transform.

  The blood flow rate calculation unit 120 calculates an average value B of the blood flow waveform at a predetermined time as a blood flow rate.

  The pulse wave amplitude calculation unit 130 calculates the amplitude C of the waveform corresponding to the pulse wave in the blood flow waveform as the pulse wave amplitude. Note that other calculation methods such as fast Fourier transform may be used as the pulse wave amplitude calculation method.

  As described above, the blood pressure decrease prediction device 100 is configured to acquire three variation parameters, ie, the pulse rate, the blood flow rate, and the pulse wave amplitude, from the blood flow waveform output from the blood flow waveform output device 800.

<Blood pressure reduction prediction process>
Next, the blood pressure reduction prediction process executed in the blood pressure reduction prediction unit 140 will be described with reference to FIG. FIG. 3 is a flowchart showing the flow of the blood pressure decrease prediction process. It is.

  In FIG. 3, when the blood pressure reduction prediction process is started, first, LV0 is output by the output unit 170 (step S110). That is, the risk level determination unit 150 sets “LV0” indicating that there is almost no or very low risk of blood pressure reduction as an initial value for the blood pressure reduction risk level, and the output unit 170 sets the set blood pressure reduction risk. The level “LV0” is output.

  Subsequently, in each of the pulse rate calculation unit 110, the blood flow rate calculation unit 120, and the pulse wave amplitude calculation unit 130, the pulse rate HR, the blood flow rate BF, and the pulse wave amplitude PW are respectively calculated (step S120). As described above, the pulse rate calculation unit 110, the blood flow rate calculation unit 120, and the pulse wave amplitude calculation unit 130 calculate the pulse rate HR, the blood flow rate BF, and the pulse wave amplitude PW based on the blood flow waveform.

  When the pulse rate HR, the blood flow rate BF, and the pulse wave amplitude PW are calculated, a subroutine for detecting changes in the pulse rate HR, the blood flow rate BF, and the pulse wave amplitude PW is started (step S130). Hereinafter, this variation detection subroutine will be described in detail with reference to FIGS. FIG. 4 is a flowchart showing the flow of processing in the pulse rate variation detection subroutine. FIG. 5 is a flowchart showing the flow of processing in the blood flow fluctuation detection subroutine. FIG. 6 is a flowchart showing the flow of processing in the pulse wave amplitude fluctuation detection subroutine.

  The fluctuations in the pulse rate HR, the blood flow rate BF, and the pulse wave amplitude PW are the following: It is detected by determining the indicated pulse wave amplitude fluctuation flag flPW. The pulse rate fluctuation flag flHR, the blood flow rate fluctuation flag flBF, and the pulse wave amplitude fluctuation flag flPW are “0” indicating no change, “1” indicating an increase, “−1” indicating a decrease, and constant after the increase, respectively. The value “2” indicating the case where the change has occurred and the value “−2” indicating the case where it becomes constant after the descent can be taken. In addition, when it becomes constant after rising (that is, it becomes “2” state), it rises again from there, “1 (2)”, when it becomes constant after rising (that is, it becomes “2” state), when it descends from there. “-1 (2)”, constant after descent (ie, “−2” state), rising from there “1 (−2)”, constant after descent (ie, “−2” state) The case of descending from there will be expressed as “−1 (−2)”.

  In FIG. 4, when determining the pulse rate variation flag flHR, first, “0” is set as the initial value fl0HR of the pulse rate variation flag flHR. If the determination subroutine for the pulse rate variation flag flHR is not the first time, the value of the pulse rate variation flag flHR determined last time is set as the initial value fl0HR (step S21).

  Subsequently, the past average value HRpast and the current value HRpre of the pulse rate HR are determined (step S22). The past average value HRpast is calculated as, for example, the past 5-minute average value. However, not only the average value but also one point such as a past maximum value may be used. The current value HRpre is calculated, for example, as an average value for the latest one minute.

  When the past average value HRpast and the current value HRpre are determined, the past average value HRpast and the current value HRpre are compared with each other (step S23). Here, when HR past> HR pre (that is, when the pulse rate HR is decreasing), the process proceeds to step S24. When HR past = HR pre (that is, when the pulse rate HR has not changed), the process proceeds to step S25. When HR past <HR pre (that is, when the pulse rate HR is increasing), the process proceeds to step S26.

  When HRpast> HRpre (that is, when the pulse rate HR is decreasing), if the initial value fl0HR is “2”, the pulse rate variation flag flHR is set to “−1 (2)”. If the initial value fl0HR is “−2”, the pulse rate fluctuation flag flHR is set to “−1 (−2)”. In other cases, the pulse rate variation flag flHR is set to “−1” (step S24).

  When HRpast = HRpre (that is, when the pulse rate HR has not changed), if the initial value fl0HR is “1 (2)”, the pulse rate variation flag flHR is set to “2”. If the initial value fl0HR is “1 (−2)”, the pulse rate variation flag flHR is set to “2”. If the initial value fl0HR is “2”, the pulse rate variation flag flHR is set to “2”. If the initial value fl0HR is “1”, the pulse rate variation flag flHR is set to “2”. If the initial value fl0HR is “0”, the pulse rate variation flag flHR is set to “0”. If the initial value fl0HR is “−1”, the pulse rate variation flag flHR is set to “−2”. If the initial value fl0HR is “−2”, the pulse rate variation flag flHR is set to “−2”. If the initial value fl0HR is “−1 (2)”, the pulse rate variation flag flHR is set to “−2”. If the initial value fl0HR is “−1 (−2)”, the pulse rate variation flag flHR is set to “−2” (step S25).

  When HRpast <HRpre (that is, when the pulse rate HR is increasing), if the initial value fl0HR is “2”, the pulse rate variation flag flHR is set to “1 (2)”. If the initial value fl0HR is “−2”, the pulse rate fluctuation flag flHR is set to “1 (−2)”. In other cases, the pulse rate variation flag flHR is set to “1” (step S26).

  As described above, the pulse rate variation flag flHR is determined and output according to the case (step S27). When the pulse rate variation flag flHR is output, the subroutine ends and returns to the main routine (ie, the process shown in FIG. 3).

  In FIG. 5, when determining the blood flow fluctuation flag flBF, first, “0” is set as the initial value fl0BF of the blood flow fluctuation flag flBF. If the determination subroutine for the blood flow fluctuation flag flBF is not the first time, the value of the blood flow fluctuation flag flBF determined last time is set as the initial value fl0BF (step S31).

  Subsequently, the past average value BFpast and current value BFpre of the blood flow rate BF are determined (step S32). The past average value BFpast is calculated as, for example, the past 5-minute average value. However, not only the average value but also one point such as a past maximum value may be used. The current value BFpre is calculated as an average value for the latest one minute, for example.

  When the past average value BFpast and the current value BFpre are determined, the past average value BFpast and the current value BFpre are compared with each other (step S33). Here, when BFpast> BFpre (that is, when the blood flow rate BF decreases), the process proceeds to step S34. When BFpast = BFpre (that is, when the blood flow rate BF has not changed), the process proceeds to step S35. When BFpast <BFpre (that is, when the blood flow BF increases), the process proceeds to step S36.

  When BFpast> BFpre (that is, when the blood flow rate BF decreases), if the initial value fl0BF is “2”, the blood flow rate fluctuation flag flBF is set to “−1 (2)”. If the initial value fl0BF is “−2”, the blood flow fluctuation flag flBF is set to “−1 (−2)”. In other cases, the blood flow fluctuation flag flBF is set to “−1” (step S34).

  When BFpast = BFpre (that is, when the blood flow rate BF has not changed), if the initial value fl0BF is “1 (2)”, the blood flow rate fluctuation flag flBF is set to “2”. If the initial value fl0BF is “1 (−2)”, the blood flow fluctuation flag flBF is set to “2”. If the initial value fl0BF is “2”, the blood flow fluctuation flag flBF is set to “2”. If the initial value fl0BF is “1”, the blood flow fluctuation flag flBF is set to “2”. If the initial value fl0BF is “0”, the blood flow fluctuation flag flBF is set to “0”. If the initial value fl0BF is “−1”, the blood flow fluctuation flag flBF is set to “−2”. If the initial value fl0BF is “−2”, the blood flow fluctuation flag flBF is set to “−2”. If the initial value fl0BF is “−1 (2)”, the blood flow fluctuation flag flBF is set to “−2”. If the initial value fl0BF is “−1 (−2)”, the blood flow fluctuation flag flBF is set to “−2” (step S35).

  When BFpast <BFpre (that is, when the blood flow BF is increasing), if the initial value fl0BF is “2”, the blood flow fluctuation flag flBF is set to “1 (2)”. If the initial value fl0BF is “−2”, the blood flow fluctuation flag flBF is set to “1 (−2)”. In other cases, the blood flow rate fluctuation flag flBF is set to “1” (step S36).

  As described above, the blood flow fluctuation flag flBF is determined and output according to the case (step S37). When the blood flow fluctuation flag flBF is output, the subroutine ends and returns to the main routine (that is, the process shown in FIG. 3).

  In FIG. 6, when determining the pulse wave amplitude fluctuation flag flPW, first, “0” is set as the initial value fl0PW of the pulse wave amplitude fluctuation flag flPW. If the determination subroutine for the pulse wave amplitude fluctuation flag flPW is not the first time, the value of the pulse wave amplitude fluctuation flag flPW determined last time is set as the initial value fl0PW (step S41).

  Subsequently, the past average value PWpast and the current value PWpre of the pulse wave amplitude PW are determined (step S42). The past average value PWpast is calculated as, for example, the past five-minute average value. However, not only the average value but also one point such as a past maximum value may be used. The current value PWpre is calculated, for example, as an average value for the latest one minute.

  When the past average value PWpast and the current value PWpre are determined, the past average value PWpast and the current value PWpre are compared with each other (step S43). Here, if PWpast> PWpre (that is, if the pulse wave amplitude PW is decreasing), the process proceeds to step S44. When PWpast = PWpre (that is, when the pulse wave amplitude PW has not changed), the process proceeds to step S45. When PWpast <PWpre (that is, when the pulse wave amplitude PW is increasing), the process proceeds to step S46.

  When PWpast> PWpre (that is, when the pulse wave amplitude PW is decreasing), if the initial value fl0PW is “2”, the pulse wave amplitude fluctuation flag flPW is set to “−1 (2)”. If the initial value fl0PW is “−2”, the pulse wave amplitude fluctuation flag flPW is set to “−1 (−2)”. In other cases, the pulse wave amplitude variation flag flPW is set to “−1” (step S44).

  When PWpast = PWpre (that is, when the pulse wave amplitude PW has not changed), if the initial value fl0PW is “1 (2)”, the pulse wave amplitude fluctuation flag flPW is set to “2”. If the initial value fl0PW is “1 (−2)”, the pulse wave amplitude fluctuation flag flPW is set to “2”. If the initial value fl0PW is “2”, the pulse wave amplitude fluctuation flag flPW is set to “2”. If the initial value fl0PW is “1”, the pulse wave amplitude fluctuation flag flPW is set to “2”. If the initial value fl0PW is “0”, the pulse wave amplitude fluctuation flag flPW is set to “0”. If the initial value fl0PW is “−1”, the pulse wave amplitude fluctuation flag flPW is set to “−2”. If the initial value fl0PW is “−2”, the pulse wave amplitude fluctuation flag flPW is set to “−2”. If the initial value fl0PW is “−1 (2)”, the pulse wave amplitude fluctuation flag flPW is set to “−2”. If the initial value fl0PW is “−1 (−2)”, the pulse wave amplitude fluctuation flag flPW is set to “−2” (step S45).

  When PWpast <PWpre (that is, when the pulse wave amplitude PW is increasing), if the initial value fl0PW is “2”, the pulse wave amplitude fluctuation flag flPW is set to “1 (2)”. If the initial value fl0PW is “−2”, the pulse wave amplitude fluctuation flag flPW is set to “1 (−2)”. In other cases, the pulse wave amplitude variation flag flPW is set to “1” (step S46).

  As described above, the pulse wave amplitude fluctuation flag flPW is determined and output according to the case (step S47). When the pulse wave amplitude fluctuation flag flPW is output, the subroutine ends and returns to the main routine (that is, the process shown in FIG. 3).

  Returning to FIG. 3, when the pulse rate variation flag flHR, the blood flow rate variation flag flBF, and the pulse wave amplitude variation flag flPW are output by the subroutine described above, the pulse rate variation flag flHR, the blood flow rate variation flag flBF, and the pulse wave amplitude variation The value of the flag flPW is compared with a preset variation pattern table.

  Hereinafter, the variation pattern table will be specifically described with reference to FIGS. FIG. 7 is a conceptual diagram conceptually showing an example of a variation pattern table relating to the pulse rate. FIG. 8 is a conceptual diagram conceptually showing an example of a variation pattern table related to blood flow. FIG. 9 is a conceptual diagram conceptually illustrating an example of a variation pattern table regarding a combination of a pulse rate and a blood flow rate. FIG. 10 is a conceptual diagram conceptually showing an example of a variation pattern table related to the pulse rate, blood flow volume, and pulse wave amplitude. FIG. 11 is a flowchart showing the flow of the risk level high determination process.

  In FIG. 7 and FIG. 8, the values of the pulse rate fluctuation flag flHR, the blood flow rate fluctuation flag flBF, and the pulse wave amplitude fluctuation flag flPW are at least the values of the pulse rate fluctuation flag flHR and the blood flow rate fluctuation flag flBF without using all three. Even if only one of them is used, the risk of lowering blood pressure can be predicted with appropriate accuracy.

  In the variation pattern table related to the pulse rate HR shown in FIG. 7, “LV0” indicating that there is almost no or very low risk of blood pressure decrease is stored as the blood pressure decrease risk level when the pulse rate variation flag flHR is “0”. Has been. As the blood pressure reduction risk level when the pulse rate fluctuation flag flHR is “1”, “LV1” indicating that the risk of blood pressure reduction is higher than “LV0” is stored. As the blood pressure lowering risk level when the pulse rate fluctuation flag flHR is “2”, “LV2” indicating that the risk of blood pressure lowering is higher than “LV1” is stored. As the blood pressure reduction risk level when the pulse rate variation flag flHR is “−1 (−2)”, “LV3” indicating that the risk of blood pressure reduction is higher than “LV2” is stored.

  In the fluctuation pattern table related to the blood flow BF shown in FIG. 8, “LV0” indicating that there is almost no or very low risk of blood pressure reduction is stored as the blood pressure reduction risk level when the blood flow fluctuation flag flBF is “0”. Has been. As the blood pressure reduction risk level when the blood flow fluctuation flag flBF is “−1”, “LV1” indicating that the risk of blood pressure reduction is higher than “LV0” is stored. As the blood pressure lowering risk level when the blood flow fluctuation flag flBF is “−2”, “LV2” indicating that the risk of blood pressure lowering is higher than “LV1” is stored. As the blood pressure reduction risk level when the blood flow fluctuation flag flBF is “−1 (−2)”, “LV3” indicating that the risk of blood pressure reduction is higher than “LV2” is stored.

  In FIG. 9, when using both the pulse rate fluctuation flag flHR and the blood flow rate fluctuation flag flBF, the risk of lowering the blood pressure is more accurate than when using at least one of the pulse rate fluctuation flag flHR and the blood flow rate fluctuation flag flBF. Can be predicted.

  In the fluctuation pattern table relating to the combination of the pulse rate and the blood flow shown in FIG. 9, the blood pressure reduction is used as the blood pressure reduction risk level when the pulse rate fluctuation flag flHR is “0” and the blood flow fluctuation flag flBF is “0”. “LV0” indicating that there is almost no risk or very low is stored. “LV1” indicating that the risk of lowering blood pressure is higher than “LV0” as the blood pressure reduction risk level when the pulse rate fluctuation flag flHR is “1” and the blood flow fluctuation flag flBF is “0”. Is stored. “LV1” indicating that the risk of blood pressure reduction is higher than “LV0” as the blood pressure reduction risk level when the pulse rate fluctuation flag flHR is “0” and the blood flow fluctuation flag flBF is “−1”. Is stored. “LV2” indicating that the risk of blood pressure reduction is higher than “LV1” as the blood pressure reduction risk level when the pulse rate fluctuation flag flHR is “1” and the blood flow fluctuation flag flBF is “−1”. Is stored. “LV3” indicating that the risk of blood pressure reduction is higher than “LV2” as the blood pressure reduction risk level when the pulse rate fluctuation flag flHR is “2” and the blood flow fluctuation flag flBF is “−1”. Is stored. “LV3” indicating that the risk of blood pressure reduction is higher than “LV2” as the blood pressure reduction risk level when the pulse rate fluctuation flag flHR is “1” and the blood flow fluctuation flag flBF is “−2”. Is stored. “LV4” indicating that the risk of blood pressure reduction is higher than “LV3” as the blood pressure reduction risk level when the pulse rate fluctuation flag flHR is “2” and the blood flow fluctuation flag flBF is “−2”. Is stored. As a blood pressure reduction risk level when the pulse rate fluctuation flag flHR is “−1 (2)” and the blood flow fluctuation flag flBF is “−2”, there is a higher risk of blood pressure reduction than “LV4”. “LV5” is stored. As the blood pressure reduction risk level when the pulse rate fluctuation flag flHR is “2” and the blood flow fluctuation flag flBF is “−1 (−2)”, there is a higher risk of blood pressure reduction than “LV4”. “LV5” is stored. As the blood pressure reduction risk level when the pulse rate fluctuation flag flHR is “−1 (2)” and the blood flow fluctuation flag flBF is “−1 (−2)”, the blood pressure lowers than “LV5”. “LV6” indicating that the risk is high is stored.

  In FIG. 10, by using all three values of the pulse rate fluctuation flag flHR, the blood flow fluctuation flag flBF, and the pulse wave amplitude fluctuation flag flPW, the risk of blood pressure reduction can be predicted with extremely high accuracy.

  In the fluctuation pattern table relating to the pulse rate, blood flow rate, and pulse wave amplitude shown in FIG. 10, the pulse rate fluctuation flag flHR is “0”, the pulse wave amplitude fluctuation flag flPW is “0”, and the blood flow fluctuation flag flBF is set. As the blood pressure reduction risk level in the case of “0”, “LV0” indicating that there is almost no risk of blood pressure reduction or extremely low is stored. As a blood pressure reduction risk level when the pulse rate fluctuation flag flHR is “0”, the pulse wave amplitude fluctuation flag flPW is “−1”, and the blood flow fluctuation flag flBF is “0”, the blood pressure lowering risk level is higher than “LV0”. “LV1” indicating that there is a high risk of blood pressure reduction is stored. As a blood pressure reduction risk level when the pulse rate fluctuation flag flHR is “1”, the pulse wave amplitude fluctuation flag flPW is “−1”, and the blood flow fluctuation flag flBF is “0”, the blood pressure lowering risk level is higher than “LV1”. “LV2” indicating that there is a high risk of blood pressure reduction is stored. As the blood pressure lowering risk level when the pulse rate fluctuation flag flHR is “0”, the pulse wave amplitude fluctuation flag flPW is “−1”, and the blood flow fluctuation flag flBF is “−1”, “LV1” Also, “LV2” indicating that there is a high risk of blood pressure reduction is stored. From “LV2”, the blood pressure lowering risk level when the pulse rate fluctuation flag flHR is “1”, the pulse wave amplitude fluctuation flag flPW is “−1”, and the blood flow fluctuation flag flBF is “−1”. Also, “LV3” indicating that the risk of blood pressure reduction is high is stored. As the blood pressure lowering risk level when the pulse rate fluctuation flag flHR is “2”, the pulse wave amplitude fluctuation flag flPW is “−1”, and the blood flow fluctuation flag flBF is “−1”, “LV3” Also stored is “LV4” indicating that there is a high risk of blood pressure reduction. As the blood pressure lowering risk level when the pulse rate fluctuation flag flHR is “1”, the pulse wave amplitude fluctuation flag flPW is “−1”, and the blood flow fluctuation flag flBF is “−2”, “LV3” Also stored is “LV4” indicating that there is a high risk of blood pressure reduction. As the blood pressure lowering risk level when the pulse rate fluctuation flag flHR is “2”, the pulse wave amplitude fluctuation flag flPW is “−1”, and the blood flow fluctuation flag flBF is “−2”, “LV4” Also, “LV5” indicating that the risk of blood pressure reduction is high is stored. As the blood pressure reduction risk level when the pulse rate fluctuation flag flHR is “−1 (2)”, the pulse wave amplitude fluctuation flag flPW is “−1”, and the blood flow fluctuation flag flBF is “−2”, “LV6” indicating that there is a higher risk of lowering blood pressure than “LV5” is stored. As the blood pressure reduction risk level when the pulse rate fluctuation flag flHR is “2”, the pulse wave amplitude fluctuation flag flPW is “−1”, and the blood flow fluctuation flag flBF is “−1 (−2)”, “LV6” indicating that there is a higher risk of lowering blood pressure than “LV5” is stored. Blood pressure decrease when the pulse rate variation flag flHR is “−1 (2)”, the pulse wave amplitude variation flag flPW is “−1”, and the blood flow rate variation flag flBF is “−1 (−2)”. As the risk level, “LV7” indicating that there is a higher risk of blood pressure reduction than “LV6” is stored.

  Such a variation pattern table preliminarily estimates experimentally, empirically, or by simulation the risk of blood pressure drop when a combination of variations in pulse rate HR, blood flow BF, and pulse wave amplitude PW occurs. Thus, it can be created in advance.

  Returning to FIG. 3, the risk level determination unit 150 determines the blood pressure reduction risk level using the reference result of the variation pattern table (step S150). The determined blood pressure reduction risk level is displayed on the monitor 500 by the output unit 170 (step S160). As a result, it is possible to inform the patient, such as the living body 900, or a related person such as a doctor or nurse, of the risk of blood pressure reduction. As a result, it is possible to perform an early treatment on the living body 900 that is at risk of lowering blood pressure.

  Further, in this embodiment, after the blood pressure reduction risk level is determined, it is determined whether or not the risk level is in a high level with a very high risk level by using short-term fluctuations in the pulse rate HR and the blood flow BF (step). S170).

  In the following, the risk level high determination process will be described in detail with reference to FIG. FIG. 11 is a flowchart showing the flow of the risk level high determination process.

  In FIG. 11, in the risk level high determination process, first, short-term changes in the pulse rate HR and the blood flow BF are calculated (step S51). The amount of change here is calculated, for example, as a ratio between the past average value and the current value at the appropriate time interval immediately before. In this case, the past average value may be calculated as an average value for the past 10 seconds, for example. Moreover, what is necessary is just to use what is calculated as an average value of the last 1 second, for example.

  Subsequently, thresholds for the above-described short-term pulse rate HR and blood flow rate BF changes are determined in accordance with the blood pressure reduction risk level determined by the risk level determination unit 150 (step S52). The threshold value is typically determined as a lower value as the blood pressure lowering risk level is higher. That is, the higher the blood pressure lowering risk level, the higher the threshold is set. More specifically, for example, the threshold corresponding to “LV0” is “40%”, the threshold corresponding to “LV1” is “35%”, and the threshold corresponding to “LV2” is “30%”, “LV3”. The corresponding threshold is “25%”, the threshold corresponding to “LV4” is “20%”, the threshold corresponding to “LV5” is “15%”, the threshold corresponding to “LV6” is “10%”, “LV7” The threshold value corresponding to “5” is set to “5%”.

  When the threshold value is determined, it is determined whether or not at least one of the change rate of the pulse rate HR and the blood flow rate BF exceeds the threshold value (step S53). Here, when at least one of the change amount of the pulse rate HR and the blood flow rate BF does not exceed the threshold value (in other words, the change amount of both the pulse rate HR and the blood flow rate BF does not exceed the threshold value) (step S53: NO ), It is determined that the risk level is not high (step S54). In other words, it is determined that there is no state in which the risk of blood pressure reduction is rapidly increasing.

  On the other hand, when at least one of the change rate of the pulse rate HR and the blood flow rate BF exceeds the threshold value (step S53: YES), it is determined whether both the change rate of the pulse rate HR and the blood flow rate BF exceed the threshold value. (Step S54). Here, when both the pulse rate HR and the change amount of the blood flow rate BF do not exceed the threshold value (in other words, when only the change amount of either the pulse rate HR or the blood flow rate BF exceeds the threshold value) (step S54: NO), it is determined that the risk level is high A (step S56). On the other hand, if both the pulse rate HR and the amount of change in the blood flow BF exceed the threshold (step S55: YES), it is determined that the risk level is in the high B state (step S57).

  Here, in particular, the risk level high B state is set to have a higher risk of blood pressure reduction than the risk level high A state. Therefore, by determining whether the risk level is high A or the risk level high B, it is possible to accurately determine whether the risk is relatively low or high even in the risk level high state.

  Returning to FIG. 3, when the risk level high state is determined, a risk level high determination result is output from the risk level high determination unit 160 (step S180). The control unit 180 controls the operation of the dialysis apparatus 600 according to the determination result of the risk level high or the blood pressure decrease risk level determined by the risk level determination unit 150 (step S190).

  The control unit 180 controls, for example, the speed and on / off of water removal in the dialysis apparatus 600, the physiological saline dosage, and the like so that the blood pressure of the living body 900 as a patient is unlikely to decrease. Therefore, it is possible to effectively reduce a decrease in blood pressure of the living body 900 as a patient.

  Note that the control unit 180 may control not only the dialysis apparatus 600 but also the operation of the blood pressure decrease prediction apparatus 100 according to various information obtained from the dialysis apparatus 600. For example, it is possible to output the risk level and the risk level high state reflecting information obtained from the dialysis machine 600. More specifically, when signals for calculating a pulse rate and a blood flow value, which are parameters for determining a risk level, are received, but dialysis is not actually performed, dialysis is performed from the dialyzer 600. It is also possible to perform control such that the risk level and the risk level high state are not output after receiving the information that the control is not performed. In this way, the operation of the apparatus can be made more efficient.

  Further, the blood pressure decrease prediction apparatus 100 automatically operates the external device such as the sphygmomanometer by sending a signal to an external device such as a sphygmomanometer according to the blood pressure decrease risk level determined by the risk level determination unit 150. You may do it.

  In addition, the blood pressure decrease prediction device 100 is configured to change each of the pulse rate calculated by the pulse rate calculation unit 110, the blood flow rate calculated by the blood flow rate calculation unit 120, and the pulse wave amplitude calculated by the pulse wave amplitude calculation unit 130. May be displayed simultaneously. In this case, the living body 900 as a patient and a related person such as a doctor or a nurse can intuitively grasp the risk of blood pressure reduction, which is very convenient in practice.

  Moreover, the blood pressure reduction prediction apparatus 100 does not necessarily need to use a risk level determination table.

  The risk level determination unit 150 may be configured to calculate a correlation value between the blood flow volume and the pulse wave amplitude, and to determine a blood pressure reduction risk level based on the calculated correlation value. For example, when the blood flow volume and the pulse wave amplitude decrease with a correlation (that is, the correlation value between the blood flow volume and the pulse wave amplitude is greater than a predetermined value, the risk level determination unit 150 determines that the blood flow volume and the pulse wave amplitude are larger. When the wave amplitude decreases), the blood pressure reduction risk level may be determined to be a relatively high level. In this case, it is possible to more appropriately determine the blood pressure reduction risk level.

  Moreover, the risk level determination part 150 may be comprised so that a blood pressure fall risk level may be determined based on the value of the average deviation of each of a pulse rate, blood flow volume, and a pulse wave amplitude. In this case, it is possible to more appropriately determine the blood pressure reduction risk level.

  The blood pressure decrease prediction device 100 is configured to determine the blood pressure decrease risk level based on other information related to the blood pressure decrease obtained from the blood flow waveform in addition to the pulse rate, the blood flow volume, and the pulse wave amplitude. Also good. In this case, it is possible to more appropriately determine the blood pressure reduction risk level. At this time, the blood pressure decrease prediction device 100 may determine the blood pressure decrease risk level based on information related to blood pressure decrease of a patient who has undergone artificial dialysis in the past.

  Further, the blood pressure decrease prediction device 100 measures the blood pressure of the living body 900 with the sphygmomanometer according to the blood pressure decrease risk level determined by the risk level determination unit 150, such as the living body 900 being a patient, a doctor, a nurse, or the like. It may be configured to prompt interested parties. Alternatively, the blood pressure decrease prediction device 100 may be configured to measure the blood pressure of the living body 900 with a sphygmomanometer according to the blood pressure decrease risk level determined by the risk level determination unit 150.

  As described above, according to the blood pressure decrease prediction apparatus 100 according to the present embodiment, the blood pressure decrease of the living body 900 can be predicted at an early stage with almost no burden on the living body 900, and the blood pressure indicating the risk that the blood pressure decrease will occur. The risk level can be appropriately determined. Furthermore, it is possible to notify the patient, such as the living body 900, or a person concerned such as a doctor or nurse, of the risk of lowering blood pressure. As a result, it is possible to perform an early treatment on the living body 900 that is at risk of lowering blood pressure.

  The present invention is not limited to the above-described embodiments, and can be changed as appropriate without departing from the spirit or idea of the invention that can be read from the claims and the entire specification. Is also included in the technical scope of the present invention. The present invention is also applicable to an apparatus for predicting dehydration symptoms in a living body. That is, for example, the level of dehydration can be determined according to the blood pressure lowering risk level.

DESCRIPTION OF SYMBOLS 100 Blood pressure fall prediction apparatus 110 Pulse rate calculation part 120 Blood flow rate calculation part 130 Pulse wave amplitude calculation part 140 Blood pressure fall prediction part 149 Fluctuation pattern table 150 Risk level determination part 160 Risk level high determination part 170 Output part 180 Control part 500 Monitor 600 Dialysis device 800 Blood flow waveform output device 900

Claims (8)

A blood pressure decrease prediction device for predicting a decrease in blood pressure of a living body,
A pulse rate calculator for calculating the pulse rate of the living body;
A blood flow rate calculation unit for calculating the blood flow rate of the living body;
A risk level determination unit that determines a risk level indicating a risk of occurrence of the blood pressure decrease based on at least one variation of the calculated pulse rate and the calculated blood flow;
There is a risk that the blood pressure decrease may occur when a fluctuation range in a predetermined period of at least one of the calculated pulse rate and the calculated blood flow exceeds a threshold determined according to the determined risk level. A risk level high determination unit that determines that the risk level is higher than the determined risk level .
The risk level high determination unit is configured to compare the calculated pulse rate and the calculated blood flow volume with a fluctuation range that exceeds a threshold determined according to the determined risk level. When the fluctuation range of both the calculated pulse rate and the calculated blood flow volume exceeds a threshold value determined according to the determined risk level, the risk level that the blood pressure decrease occurs is higher. A blood pressure decrease prediction apparatus characterized by determining that there is a blood pressure.   The risk level determination unit determines the risk level by referring to a predetermined risk level determination table in which at least one variation of the pulse rate and the blood flow is associated with the risk level. The blood pressure reduction prediction apparatus according to claim 1, wherein the apparatus is a blood pressure decrease prediction apparatus. The pulse rate calculation unit calculates the pulse rate of the living body based on a blood flow waveform indicating a change in blood flow of the living body over time,
The blood pressure reduction prediction apparatus according to claim 1, wherein the blood flow rate calculation unit calculates a blood flow rate of the living body based on the blood flow waveform. A pulse wave amplitude calculating unit for calculating the pulse wave amplitude of the living body;
The risk level determination unit is a risk indicating a risk of blood pressure reduction based on fluctuations in the calculated pulse wave amplitude in addition to at least one of the calculated pulse rate and the calculated blood flow rate. The blood pressure decrease prediction apparatus according to claim 1, wherein the level is determined. The risk level determination unit refers to a predetermined risk level determination table in which at least one of the pulse rate and the blood flow volume and a combination of fluctuations of the pulse wave amplitude are associated with the risk level. The blood pressure lowering prediction apparatus according to claim 4 , wherein the risk level is determined by: The pulse rate calculation unit calculates the pulse rate of the living body based on a blood flow waveform indicating a change in blood flow of the living body over time,
The blood flow rate calculation unit calculates the blood flow rate of the living body based on the blood flow waveform,
The blood pressure decrease prediction device according to claim 4, wherein the pulse wave amplitude calculation unit calculates the pulse wave amplitude of the living body based on the blood flow waveform.   The blood pressure decrease prediction device according to claim 1, further comprising a first output unit that outputs the risk level determined by the risk level determination unit to the outside.   The blood pressure decrease prediction device according to claim 1, further comprising a second output unit that outputs a risk level high state determined by the risk level high determination unit to the outside.

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