JP5202734B2 - Blood flow measuring device and method - Google Patents

Description

  The present invention relates to a technique for measuring blood flow in a skin tissue percutaneously. For example, the present invention relates to a technique for calculating blood flow by measuring skin temperature.

  As a technique for measuring the blood flow volume in the skin tissue percutaneously, a method of irradiating a measurement target site with a laser beam and a method using a heat conduction effect are known.

  One example of the former is a laser tissue blood flow measurement method (see Patent Document 1 (FIG. 1) and Patent Document 2 (FIG. 1)). In the case of this method, the blood flow rate is calculated by analyzing the frequency of the intensity change superimposed on the intensity of the reflected light signal or scattered light signal obtained when the laser beam is irradiated to the measurement target site (for example, skin). .

  One example of the latter is the crossover thermocouple method (Unique Medical product UM-200A data). In this method, a heating point and a temperature measuring point close to the heating point are provided on the skin surface of the measurement target, and the temperature is measured at the temperature measuring point simultaneously with the heating at the heating point, and the amount of heating is feedback controlled. This is a method for keeping the temperature constant. In the case of this method, the blood flow rate is calculated based on the principle that the change in the heating amount at the heating point is proportional to the subcutaneous blood flow rate.

JP-A-5-7559 Japanese Patent Laid-Open No. 7-113743

S. Kashima et al .: Model for measurement of tissue oxygenated blood volume by the dynamic light scattering method, J.J.Appl.Phys., 31,4097-4102 (1992)

  However, in any of the above-described methods, the configuration of the measuring device becomes complicated, or the demand for advanced signal processing technology for the obtained measurement signal makes it unavoidable to increase the size and cost of the device. Yes.

  An object of the present invention is to make it possible to easily measure a blood flow rate by a simple device configuration and a simple signal processing technique in view of the above-described problems of the prior art.

  In order to achieve the above-described object, the present invention measures the temperature profile of the process in which the skin temperature of the measurement target region recovers to the thermal equilibrium state immediately after the application of the heat load to the skin that is the measurement target region is completed. A technique for measuring blood flow based on the results is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the blood volume of a measurement object site | part can be measured, using a simple apparatus structure and signal processing technique.

It is a figure which shows schematic structure of the blood flow rate measuring apparatus which concerns on embodiment of invention. It is a figure explaining the structural example of the heat absorber stationary type blood flow measuring device. It is a figure explaining the structural example of a heat absorber slide type blood flow measuring device. It is a figure explaining the structural example of the blood flow rate measuring apparatus using a contact-type skin thermometer. It is a figure explaining the structural example of a heat absorber. It is a figure explaining the structural example of the heat absorber with a cooling unit. It is a figure explaining the structural example of the heat absorber which attached the thermal radiation part and the cooling part. It is a figure explaining the other structural example of a heat absorber. It is a figure explaining the structural example of the blood flow rate measuring device of a multiple finger measurement type. It is a figure which shows the example of a medical display screen. It is a figure which shows the example of a display screen for home use. It is a figure explaining the example of a measurement processing method. It is a figure explaining the example of a calculation model of blood flow. It is a figure explaining the recovery process of a blood flow rate calculation model and skin temperature. It is a figure explaining the measurement profile of skin temperature.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. The drawings are drawn exclusively for the purpose of explaining the invention, and can be combined with or replaced with known or well-known techniques.

(Basic principle)
The recovery process of the surface temperature observed when a thermal load is applied to the finger, such as soaking in cold water or hot water, depends on the blood flow (ω) inside the finger. Numerical and experimental studies on biological heat transport phenomena: reported by Kaken Riken et al.

  For example, when a finger in a thermal equilibrium state is immersed in cold water for a certain period of time and then taken out from the cold water and allowed to rest at room temperature, the surface temperature of the finger changes as follows. First, when the finger is immersed in cold water, the temperature of the finger surface that has been in a thermal equilibrium state temporarily decreases from the initial temperature. Next, when the finger is taken out of the cold water, the temperature of the finger surface slowly recovers and finally reaches the initial temperature. In this recovery process, there is a difference in the rate of temperature change between when the blood flow is high and when it is low. That is, the rate of temperature change when the blood flow rate is high is high, and conversely, the rate of temperature change when the blood flow rate is low is low. This phenomenon suggests that the blood flow inside the finger can be estimated using the temperature measurement profile in the temperature recovery process after the end of the thermal load, particularly the temperature change of the finger surface due to the thermal load.

  In the following embodiments, an example of an apparatus for measuring blood flow through measurement of finger surface temperature will be described. In the following description, the case where the surface temperature of the finger of the hand is exclusively measured will be described. However, there is no limitation on the measurement site as long as the sensor can contact the sensor such as the tip of the toe, the palm, and the sole of the foot.

(Example 1)
FIG. 1 shows a schematic configuration example of a blood flow measuring device. The blood flow measurement device according to the embodiment includes a main body 101, a measurement region 102, a heat absorber 103, a lid 104, an environmental thermometer 105, a skin surface thermometer 106, a movable plate 107, an operation button 108, a display unit 109, an LED 110, It has a heat insulating structure 111, a signal processing unit 112, an external communication unit 113, and a core thermometer 114.

  The main body 101 according to the embodiment has a substantially rectangular parallelepiped shape. The main body 101 is made of plastic resin, metal or the like. The measurement area 102 is disposed on the surface of the main body 101. The measurement area 102 is used for placing a finger when measuring blood flow. A hole 102 </ b> A is formed at the mounting position of the fingertip that is the measurement site in the measurement region 102. This hole 102 </ b> A communicates with the inside of the main body 101.

  For the heat absorber 103, a material having excellent thermal conductivity capable of efficiently removing heat from the skin surface is used. For example, metal or heat absorbing gel gel is used. In this embodiment, the lid 104 is rotatably attached to the housing of the main body 101. The lid 104 is rotated so as to expose the measurement region 102 and the environmental thermometer 105 to the surface of the housing when measuring the blood flow, and is rotated so as to cover the measurement region 102 and the environmental thermometer 105 when not in use and stored. Is done. Of course, a slide mechanism may be employed to open and close the lid 104, or a structure that can be detached from the housing may be employed. By closing the lid 104, dust or the like can be prevented from entering the housing through the hole 102A.

  The environmental thermometer 105 is a thermometer that measures the outside air temperature, which is the usage environment of the blood volume measuring device. Skin surface thermometer 106 is a thermometer that measures the temperature of a fingertip that is a measurement site. In the case of this embodiment, a non-contact type thermometer is used as the skin surface thermometer 106. For this reason, the skin surface thermometer 106 is disposed in the main body 101 at a position where the hole 102A can be seen. In the case of FIG. 1, the skin surface thermometer 106 is disposed vertically below the hole 102A.

  The movable plate 107 is a movable part that is used to move the heat absorber 103 to a load position (a position where the surface of the heat absorber 103 touches the finger) and move the heat absorber 103 into the housing. The movable plate 107 is moved by a driving mechanism (not shown). For example, the movable plate 107 is driven to retract the heat absorber 103 from the measurement position when measuring the skin temperature, and to position the heat absorber 103 at the measurement position when a heat load is applied. In the case of FIG. 1, the movable plate 107 is rotatably attached to the inner wall of the housing on one end side where the heat absorber 103 is not attached, and the rotation angle is adjusted by a motor or the like (not shown). In FIG. 1, the movable direction of the movable plate 107 is indicated by an arrow.

  The operation button 108 is a button for operating an instruction input to the signal processing unit 112 or the computer system and power supply / supply stop. For example, it is used for switching the content displayed on the display unit 109 (measurement result, history) and setting time. The operation button 108 can also be configured as a switch.

  The display unit 109 is a display device used for displaying measurement procedures and measurement results. For example, a liquid crystal display or an organic EL display is used. The LED 110 is used to teach a user about measurement time and measurement progress. In the case of FIG. 1, four levels of information are taught according to the number of lighting. However, the number of LEDs 110 is not limited to four. Further, a method of teaching the user necessary information by changing the light emitting color or lighting state of the LED 110 (for example, blinking) may be adopted. Further, a method of notifying the user of the measurement time and the progress of measurement through sound (including sound) and the display content of the display unit 109 without disposing the LED 110 may be employed.

  The heat insulating structure 111 is arranged to prevent the heat of the signal processing unit 112 and the like from affecting the skin surface thermometer 106. In the case of FIG. 1, the heat insulating structure 111 is arranged so as to partition a main heat source inside the housing and a space where the skin surface thermometer 106 is arranged. The signal processing unit 112 performs control of the internal system accompanying the calculation of blood flow based on the measured temperature and the measurement operation. The signal processing unit 112 is configured by a computer system, for example. In the case of this embodiment, the signal processing unit 112 controls the movable position of the movable plate 107 and the lighting state of the LED 110 as the blood flow measurement operation progresses. A program necessary for the control is stored in a storage device (not shown). Further, the temperature measured in a timely or continuous manner from each thermometer in connection with the blood flow measurement is also stored in a storage device (not shown). The external communication unit 113 is an interface used for communication with an external device.

  The nuclear thermometer 114 is a thermometer that measures the nuclear temperature of the subject. Nuclear body temperature is also called core temperature or deep temperature. As the core thermometer 114, a thermometer corresponding to the measurement site is used. Measurement sites include, for example, the sublingual, inner ear, armpit, and rectum. In the case of FIG. 1, the environmental thermometer 105 and the core thermometer 114 are integrally arranged in the blood flow measuring device, but the environmental temperature and the core body temperature are values measured using other thermometers. A method of acquiring through the external communication unit 113 may be employed, or a method of manually inputting by the subject himself / herself through the operation buttons 108 or the like may be employed.

  Subsequently, a temperature measurement method by the blood flow measuring device according to the embodiment will be described. In the case of this embodiment, measurement of the temperature of the finger skin surface will be described. The skin surface temperature is measured by a skin surface thermometer 106. First, with the finger placed on the measurement region 102, an initial temperature (temperature in a thermal equilibrium state) before applying a heat load is measured. Next, the heat absorber 103 is positioned in the hole 102 </ b> A of the measurement region 102 by the movable plate 107. Thereby, the surface of the heat absorption body 103 contacts the skin surface of the finger, and the skin temperature is taken away. The application of the heat load is executed for a predetermined time set in advance.

  When the application of the heat load for a certain time is completed, the heat absorber 103 is retracted from the hole 102A to the retracted position by the movable plate 107. Simultaneously with the withdrawal of the heat absorber 103, measurement of the skin surface temperature by the skin surface thermometer 106 is started. This measurement is a measurement of the temperature profile in the recovery process after application of the thermal load. Accordingly, the skin temperature measurement is performed continuously. Preferably, the temperature measurement is continued until the initial temperature is restored.

  When the measurement of the skin temperature described above is completed, the measurement of the nuclear body temperature using the nuclear thermometer 114 and the measurement of the environmental temperature (room temperature) using the environmental thermometer 105 are subsequently executed. Each temperature measured by these three types of thermometers is given to the signal processing unit 112, and is calculated as a blood flow rate based on a calculation process described later. In the case of this embodiment, the core body temperature and the environmental temperature are measured after the skin temperature is measured. However, the measurement order is not limited to the order described above because three types of temperatures may be measured.

  Next, a method for measuring blood flow based on the temperature profile of the skin temperature recovery process will be described. FIG. 15 shows an example of time-series data of changes in skin temperature and room temperature during blood flow measurement. As described above, among the skin temperatures in the figure, the speed of the temperature change in the recovery process varies depending on the blood flow rate. FIG. 13 shows a calculation model for deriving the blood flow rate. FIG. 13A shows a calculation model before the finger contacts the heat absorber, and FIG. 13B shows a calculation model after the finger contacts the heat absorber.

  In the figure, Ta is blood flow temperature (nuclear body temperature), Ts is skin temperature, and Tr is room temperature. R1 is the internal thermal resistance, R2 is the thermal resistance to the air on the skin surface, and C1 is the heat capacity of the skin surface tissue. Incidentally, R1 has a characteristic inversely proportional to the thermal conductivity (including a component proportional to the blood flow ω). In FIG. 13A, it is assumed that the skin temperature of the finger before coming into contact with the heat absorber 103 is saturated to room temperature, and the skin temperature at this time is represented by Ts (0). In FIG. 13B, the skin temperature after the heat absorber 103 has been in contact with the skin temperature for t1 time is represented by Ts (t1). FIG. 14A shows an equivalent circuit of the calculation model shown in FIG. 13, and FIG. 14B shows a state of finger temperature recovery.

At times t = 0 and t = ∞, the finger skin temperature is in equilibrium with room temperature. In this state, it is considered that the capacitor C1 of the equivalent circuit is in a charged state. Therefore, the following equation is established from the circuit diagram of FIG.

In the process of recovering the skin surface temperature from Ts (t1) to Ts (0), as shown in FIG. 14B, the temperature rises according to the time constant τ = R1 · C1. For this reason, the following formula is established together with (Formula 1).

  It is assumed that the values of Ta, R1, R2, and C1 are obtained by trial and error in an optimal solution corresponding to the actual device configuration. Here, R1∝1 / ω. That is, R1 is proportional to the blood flow rate ω. Therefore, the signal processing unit 112 obtains the blood flow rate at the fingertip of the subject's hand by giving the temperature measured by each thermometer to Equation 2 and obtaining R1 satisfying Equation 2 by calculation.

  FIG. 12 shows an example of a blood flow measurement procedure executed by the blood flow measurement device according to the embodiment. When blood volume measurement is started in response to an operation input to the operation button 108, the signal processing unit 112 presents the measurement start to the subject through the LED 110, the display unit 109, and the like (step S1).

  When the measurement start is presented, the subject places his finger on the measurement region 102. At this time, the signal processing unit 112 measures the initial temperature of the skin and measures the room temperature with the environmental thermometer 105 (step S2). Next, in order to remove the heat of the skin, the signal processing unit 112 drives and controls the movable plate 107 to bring the heat absorber 103 into contact with the skin for a certain time (step S3).

  When the predetermined time has elapsed, the signal processing unit 112 drives and controls the movable plate 107 to retract the heat absorber 103 from the skin (step S4). Immediately after the evacuation, the signal processing unit 112 measures how the skin temperature that has decreased due to the heat absorbed by the heat absorber 103 is recovered by the skin surface thermometer 106 (step S5). At this time, the signal processing unit 112 also measures the room temperature through the environmental thermometer 105 and checks the stability of the room temperature during the measurement.

  When the skin surface temperature recovers, the signal processing unit 112 presents the measurement of the core body temperature to the subject through the LED 110 and the display unit 109, and measures the subject's core body temperature through the core thermometer 114 (step S6).

  When the measurement of the core body temperature is also completed, the signal processing unit 112 presents the end of the measurement to the subject through the LED 110 and the display unit 109 (Step S7). Thereafter, the signal processing unit 112 gives the measured temperature to (Equation 2), and obtains the value of R1 proportional to the blood flow ω as described above (step S8). When the value of R1 is obtained, the signal processing unit 112 displays information related to the blood flow obtained according to the calculated value of R1, and ends the series of processes (step S9). Note that operations and instructions generated in connection with the measurement of blood flow can also be performed through opening / closing of the lid 104, a buzzer sound, a voice guide, and the like. Note that the measurement timing of the environmental temperature and the nuclear body temperature is not necessarily limited to the procedure of FIG.

  As described above, in the case of the blood flow measurement device according to this embodiment, a temperature in the process of applying a heat load to the skin surface of the finger by the contact of the heat absorber 103 and then recovering the finger skin temperature. Blood flow is measured by continuously measuring the profile. For this reason, apparatus configuration and signal processing can be simplified as compared with the prior art.

  Further, in the case of the blood volume measuring device according to this embodiment, the rotation type lid 104 is used, so that it is possible to avoid dust and the like from adhering to the skin surface thermometer 106 located below the hole 102A. With this structure, it is possible to avoid a decrease in detection accuracy by the skin surface thermometer 106. In addition, it is possible to prevent dust and the like from adhering to the electronic component and the driving mechanism to cause malfunction.

(Example 2)
FIG. 2 shows another schematic configuration example of the blood flow measuring device. In FIG. 2, parts corresponding to those in FIG. 1 are denoted by the same reference numerals. As shown in FIG. 2, the basic device configuration is the same as that of the first embodiment.

  The difference between the blood flow measuring device according to this embodiment and Embodiment 1 is that the heat absorber 103 is fixedly arranged on the surface of the main body 101. In the case of FIG. 2, the heat absorber 103 is arranged at a position aligned with the measurement region 102.

  Also in this embodiment, the basic temperature measurement procedure is the same as that in Embodiment 1. However, since the heat absorber 103 is fixed, the contact timing between the finger and the heat absorber 103 cannot be automatically controlled. Therefore, in the case of this embodiment, a method of notifying the user of the contact timing through the control of the display content of the display unit 109 and the lighting state of the LED 110 is employed. Of course, the control related to this notification is realized through the signal processing unit 112.

  Below, the method to measure skin temperature is demonstrated. First, the subject places his / her finger on the measurement region 102 according to a signal from the display unit 109 or the LED 110. At this time, the skin surface thermometer 106 measures the initial value of the skin temperature in conjunction with the signal.

  Next, the notification mode of the display unit 109 and the LED 110 changes. The test subject moves the finger placed on the measurement region 102 to the surface of the heat absorber 103 using the change in the notification mode as a signal.

  When a certain time elapses, the notification mode of the display unit 109 and the LED 110 further changes. The subject moves the finger placed on the heat absorber 103 to the measurement region 102 using the change in the notification mode as a signal. Thereafter, the skin surface thermometer 106 measures a temperature change in the process of recovering the skin temperature.

  As described above, in the case of this embodiment, the procedure is exactly the same as that of Embodiment 1 except that the subject himself / herself needs to move the finger to be measured according to the progress of the blood flow measurement process. Thus, the blood flow can be measured.

  In the case of this embodiment, since the heat absorber 103 is disposed on the surface of the housing, the heat absorber 103 can be cleaned when it becomes dirty. Further, the heat absorber 103 can be easily replaced even when the heat absorber 103 is damaged or the function is deteriorated. In addition, the cooling effect can be adjusted by replacing the heat absorber 103 with a different material.

  Furthermore, in the case of this embodiment, the movable plate 107 which is a movable part is unnecessary, so that the apparatus configuration is simplified and the possibility of failure can be further reduced. In the case of this embodiment, the size of the heat absorber 103 can be determined regardless of the size of the hole 102A. In the case of the first form example, in order to bring the surface of the heat absorber 103 into contact with the finger, the shape needs to be smaller than the hole 102A.

  However, in the case of this embodiment, since it is not necessary to determine the size of the heat absorber 103 due to the relationship with the size of the hole 102A, the surface size of the heat absorber 103 can be made larger than in the case of Embodiment 1. Therefore, the contact area with the finger can be easily increased. Further, the heat capacity of the heat absorber 103 can be easily increased. As a result, in the case of this embodiment, the heat absorption effect by the heat absorber 103 can be enhanced. This means that the time for applying the heat load can be shortened.

(Example 3)
FIG. 3 shows another schematic configuration example of the blood flow measuring device. In FIG. 3, parts corresponding to those in FIG. As shown in FIG. 3, the basic device configuration is the same as that of the first embodiment.

  The difference between the blood flow measuring device according to this embodiment and Embodiment 1 is that the heat absorber guide 301 is used for the movement of the heat absorber 103. That is, in the case of this embodiment, the heat absorber 103 or its stand is conveyed along the heat absorber guide 301. At this time, the space length in the thickness direction of the housing necessary for the movement of the heat absorber 103 is smaller than that when the movable plate 107 is driven to rotate. Therefore, by adopting the structure of this embodiment, the length in the height direction of the AA cross-sectional view of the blood flow measuring device can be reduced. That is, the volume of the blood flow measuring device can be reduced.

(Example 4)
FIG. 4 shows another schematic configuration example of the blood flow measuring device. In FIG. 4, parts corresponding to those in FIG. As shown in FIG. 4, the basic device configuration is the same as that of the second embodiment.

  The difference between the blood flow measuring device according to this embodiment and the embodiment 2 is that a contact thermometer 401 is used instead of the skin surface thermometer 106. In the case of this embodiment, since the fixed heat absorber 103 is disposed in the vicinity of the measurement region 102, the subject himself / herself needs to move his / her finger as in the case of Embodiment 2.

  Incidentally, since the contact thermometer 401 is generally inexpensive, the apparatus cost can be reduced as compared with the case where the temperature of the skin surface is measured using a non-contact type thermometer. Further, since the contact thermometer 401 itself is arranged on the surface of the casing, the maintenance is facilitated as compared with the case of the second embodiment. Further, unlike the case of a non-contact type thermometer, it is not necessary to provide a distance between the thermometer and the finger by a distance suitable for measurement, and accordingly, the volume of the blood flow measuring device can be reduced accordingly. it can.

  In the case of this embodiment, the contact thermometer 401 can also be used as the environmental thermometer 105. In this case, the number of thermometers mounted on the blood flow rate measuring device can be reduced by one compared to other embodiments.

(Example 5)
In the case of the blood flow measuring device according to this embodiment, a heat insulating material is disposed on the surface of the measurement region 102. In any of the first to fourth embodiments, while the finger skin temperature is measured, the finger contacts the measurement region 102 at a portion around the measurement location. Although depending on the material of the measurement region 102, heat transfer occurs between the finger and the contact portion. In particular, when the heat transfer is large, the influence on the measured skin temperature cannot be ignored. Therefore, at least a portion of the measurement region 102 that may come into contact with the finger is covered with a heat insulating material to minimize heat transfer between the finger and the measurement region 102 (or the apparatus main body) during skin temperature measurement. In the case of this embodiment, the measurement accuracy can be improved as compared with the blood flow measuring device according to the above-described four embodiments.

(Example 6)
In the case of the blood flow measuring device according to this embodiment, a heat absorber 103 having a convex cross section as shown in FIG. 5 is used. FIG. 5A is a view as seen from the side on which the subject's finger comes into contact (housing surface side), and FIG. 5B is a cross-sectional view taken along the line AA. In the case of FIG. 5, the heat absorber 103 employs a structure in which cylinders having different diameters are stacked in two stages. The cylinder with the smaller diameter is the contact surface with the skin. Note that the area of the portion in contact with the finger is a size that can be adapted to a narrow range such as a fingertip.

  In the case of FIG. 5, both the upper stage and the lower stage are constituted by cylinders. Further, the shape may be different between the upper stage and the lower stage. However, from the viewpoint of increasing the heat capacity of the heat absorber 103, it is desirable that the volume on the lower side is larger than the volume on the upper side. Further, instead of the two-stage structure as shown in FIG. 5, the heat absorber 103 may have a shape in which an upper portion of a cone shape or other cone shape is cut out in parallel with the bottom surface.

  Note that the material of the heat absorber 103 is preferably a metal body in view of thermal conductivity. For example, copper, gold, silver or an alloy containing these with good thermal conductivity is preferable. However, ABS resin or the like may be used depending on the size of the heat absorber 103.

(Example 7)
In the case of the blood flow measuring device according to this embodiment, a structure for heating or cooling the heat absorber 103 is added in order to efficiently remove heat from the skin surface. FIG. 6 shows a structural example when a cooling mechanism is attached to the heat absorber 103. FIG. 6 shows a structural example in which a Peltier element 604 is attached to the lower surface of the heat absorber 103 employed in Embodiment 6 (FIG. 5) with a cooling gel 603 interposed therebetween. The Peltier element 604 is a cooling structure. The cooling gel 603 is used to efficiently release the heat of the heat absorber 103 to the Peltier element 604.

(Embodiment 8)
In the case of the blood flow measuring device according to this embodiment, a mechanism for monitoring the cooling effect of the heat absorber 103 and increasing the measurement accuracy of the skin temperature is adopted. Specifically, a thermometer 601 is disposed in the vicinity of the end face that contacts the skin of the heat absorber 103, and a thermometer 602 is disposed in the vicinity of the end face on the side that radiates the absorbed heat. For the thermometers 601 and 602, for example, a thermistor is used.

  In the case of this embodiment, the signal processing unit 112 detects the temperatures of the thermometers 601 and 602, respectively. In the case of this embodiment, the signal processing unit 112 determines whether or not to start the blood flow measurement process depending on whether or not the temperature of the thermometer 601 on the side in contact with the skin has reached a certain temperature. This is because if the blood flow measurement process is started in a state where the temperature is not stable, the measurement accuracy of the blood flow may be reduced due to an external factor.

  The signal processing unit 112 also determines whether the temperature of the thermometer 601 is lower than room temperature when determining whether to start the blood flow measurement process. This is because if the temperature of the heat absorber 103 is higher than room temperature, the skin temperature cannot be effectively absorbed and the measurement conditions are not satisfied.

  In addition, when the blood flow measurement process is started and the heat absorption pair 103 is brought into contact with the skin, the signal processing unit 112 measures the temperature difference between the thermometers 601 and 602 to thereby apply the heat absorption body 103 to the heat absorption body 103. Calculate the amount of heat transferred. Note that the calculation of the amount of heat transferred based on the temperature difference is known and will not be described. In the case of this embodiment, the signal processing unit 112 retracts the heat absorber 103 from the contact position with the finger on the condition that the amount of absorption moved from the finger to the heat absorber 103 exceeds a predetermined threshold. . By adopting such control, blood flow can be measured under the same conditions. As a result, the measurement accuracy of the blood flow rate ω can be improved.

(Example 9)
In the case of the blood flow measuring device according to this embodiment, a method of positively controlling the heat transfer amount to a constant value while applying the heat load of the temperature and heat amount of the heat absorber 103 at the start of measurement is adopted. To do. In this example, a Peltier element (FIG. 6) or an air cooling fan is used to cool the heat absorber 103. Further, a heater (not shown) is used for heating the heat absorber 103. By actively managing the temperature by the signal processing unit 112, the temperature at the start of blood flow measurement can be actively controlled to the optimum temperature. The optimum value here is preferably a value set in consideration of the relationship with the room temperature.

  In the case of the embodiment 8, the amount of movement heat is controlled to be constant by adjusting the contact time between the finger and the heat absorber 103. In the case of this embodiment, for example, the contact time is constant. Even in this case, it is possible to make the amount of heat transferred within a certain contact time constant by cooling or overheating of the heat absorber 103. In any case, the measurement accuracy of the blood flow ω can be improved by making the measurement conditions the same.

(Example 10)
In the case of the blood flow measuring device according to this embodiment, a structure that further enhances the heat dissipation effect is adopted. Specifically, as shown in FIG. 7, a structure in which a heat radiating fan 701 and heat radiating fins 702 are attached to the heat absorber 103 is employed. In the case of FIG. 7, an example in which the heat radiating fan 701 and the heat radiating fins 702 are attached to the structure of Embodiment 7 (FIG. 6) is shown. A structure in which only the heat radiating fan 701 is attached is also possible. Further, a metal plate for heat dissipation may be attached instead of the heat dissipation fin. In any case, the heat dissipation efficiency of the heat absorber 103 can be improved as compared with the embodiment described above. By improving the thermal efficiency, the time required for re-measurement by the blood flow measuring device can be shortened, and the measurement efficiency can be improved.

(Example 11)
In the case of Embodiment 11, another structural example suitable for use in the heat absorber 103 is shown. 8A to 8F show structural examples of the heat absorber 103. FIG. In each figure, the upper side is a view of the heat absorber 103 as viewed from the upper surface side, and the lower side is a cross-sectional view taken along the line AA. Incidentally, the heat absorbing body 103a shown in FIG. 8A is a type in which the cylinders described in Embodiment 6 are stacked in two stages. The heat absorber 103b shown in FIG. 8B is a type in which the upper part of the cone described in the sixth embodiment is cut off in parallel with the bottom surface. The heat absorber 103a shown in FIG. 8C is the column type described in the first embodiment. These shapes are selectively used according to the body size of the blood flow measuring device to which these shapes are applied, the attachment method and drive mechanism of the body, and the layout inside the body. 8D to 8F are types in which the contact surface with the skin in FIGS. 8A to 8C is processed into a curved shape. By processing the contact surface into a curved surface, the degree of adhesion with the skin can be increased and the endothermic effect can be enhanced.

(Example 12)
FIG. 9 shows another schematic configuration example of the blood flow measuring device. In FIG. 9, parts corresponding to those in FIG. However, the present invention can also be applied to the case where the fixed heat absorber 103 is used as in the blood flow measuring device shown in FIG. In the case of the blood flow measuring device according to this embodiment, two measurement regions 102 are arranged side by side on the housing. Of course, a movable plate 107 as a mechanism unit for moving the heat absorber 103 between the measurement position and the retracted position is disposed inside the housing.

  In the case of this embodiment, since there are two measurement regions 102, blood flow of two fingers located next to each other can be measured, for example. In addition, for example, the blood flow of one finger on each of the right hand and the left hand can be measured. In addition, for example, blood flow in adjacent or adjacent skin can be measured. The blood flow may be measured simultaneously or at a time difference. In any case, the blood flow volume can be measured at a plurality of locations, so that variations in blood flow volume depending on the measurement position can be averaged. As a result, the reliability of the blood flow measurement result for the subject can be increased. Moreover, the measurement time length until an average value is calculated can be shortened compared with the case where the measurement of the blood flow rate for a subject is performed a plurality of times and the average value thereof is calculated by the signal processing unit 112.

  In addition, by arranging a plurality of measurement regions 102, measurement results for other measurement regions 102 can be used even when measurement for any one of the measurement regions 102 fails.

(Example 13)
In the case of the blood flow measuring device described above, the case where the signal processing unit 112 calculates the blood flow based on the three types of measured temperatures has been described. However, the measured temperature data and the measured blood flow volume may be linked with another index of another measuring device that can communicate through the external communication unit 113. In addition, the function of the blood flow measuring device described above may be equipped with the function of a device indicating another indicator, or conversely, the blood flow measuring device may be integrally attached inside the device indicating another indicator. good. Incidentally, other indicators here include, for example, metabolism, thermal sensation, stress, and autonomic nerve function. The external communication unit 113 may be used not only to output the measured temperature and the calculated blood flow value to the outside, but also to receive various setting values for the blood flow measuring device.

(Example 14)
10 and 11 show display examples of measurement results obtained by the signal processing unit 112. FIG. FIG. 10 is an example of displaying the measured blood volume ω as a real value. This display is suitable for, for example, a blood flow measuring device used in a medical institution. FIG. 11 is an example in which the measured blood flow ω is displayed by comparison with the previous value or the average value. For example, the display is divided into levels such as “the blood flow is less than (previous value)” and “the blood flow is greater than (previous value)”. The average value here includes not only an average value of past measurement results of a specific individual but also an average value statistically determined by sex, age group, and the like. This display is suitable for a blood flow measuring device used in non-medical institutions. The display may be combined with color coding or other display forms.

(Example 15)
In each of the above-described embodiments, the case where the heat load applied to the skin surface temperature is cooling has been described. However, the heat load may be heating. What is necessary is just to use a heater and a warm air generation | occurrence | production part for heating the skin surface. Even when the heat load is warming, the principle applied is exactly the same, and it is only necessary to measure the temperature change in the process in which the skin surface temperature returns to the thermal equilibrium state after the heat load is applied.

  Conventionally, it is known that the blood flow in each part of the body represents an index related to physical condition, health, and the like. For example, when peripheral blood flow worsens, it causes coldness and numbness and skin damage. In addition, it causes cracks and red spots due to peripheral vascular disorders. Sympathetic nerves also release adrenaline. Since adrenaline has the effect of constricting blood vessels, sympathetic nerve tension continues, resulting in systemic blood circulation disorders. That is, the peripheral blood flow can be measured to analyze the state of autonomic nerve activity. In addition, movements to observe peripheral blood flow to see effects such as exercise testing and rehabilitation are increasing (http://ci.nii.ac.jp/naid/110002521799/non-invasive using electromagnetic induction) Peripheral blood flow monitoring system). Thus, by simply measuring the blood flow itself, it can be used as a device for health check, stress check and the like.

DESCRIPTION OF SYMBOLS 101 ... Main body, 102 ... Measurement area, 103 ... Heat absorber, 104 ... Cover, 105 ... Environmental thermometer, 106 ... Skin surface thermometer, 107 ... Movable plate, 108 ... Operation button, 109 ... Display part, 110 ... LED , 111 ... heat insulation structure, 112 ... signal processing unit, 113 ... external communication unit, 114 ... nuclear thermometer, 301 ... heat absorber guide, 401 ... contact thermometer, 601, 602 ... thermometer, 603 ... cooling gel, 604 ... Peltier element, 701 ... Radiation fin.

Claims (10)

A measurement region that contacts the skin surface of the measurement target site when measuring blood flow, and
A skin surface thermometer for measuring the skin surface temperature of the measurement target part placed in the measurement region;
A thermal load application unit that applies a thermal load to the measurement target site when measuring blood flow;
After the application of the thermal load, a temperature change measurement unit that measures the temperature change of the skin temperature of the measurement target site through the skin surface thermometer ;
A blood flow measuring device having an environmental temperature, a nuclear body temperature, and a signal processing unit that calculates a blood flow of the measurement target part based on a temperature change after the application of the heat load is completed . The blood flow measuring device according to claim 1 , wherein a heat insulating material is disposed in a region portion excluding a region where the measurement target region is disposed in the measurement region. The blood flow rate according to claim 1 or 2 , wherein a heat insulating structure is arranged around the skin surface thermometer so that heat other than the measurement target region does not affect the measurement result of the skin surface thermometer. measuring device. Temperature of a portion in contact with the measurement target sections of the heat load applying unit, to any one of claims 1 to 3, characterized in that it comprises means for monitoring to be constant at application start of heat load The blood flow measuring device as described. The blood flow measuring device according to any one of claims 1 to 4 , further comprising means for monitoring so that the amount of heat transferred through the heat load application unit is constant during application of the heat load. The blood flow measuring device according to any one of claims 1 to 5 , wherein the thermal load application unit is a heat absorber that takes heat away from a skin surface of a measurement target site. The blood flow measuring device according to claim 6 , wherein the thermal load application unit includes a heat dissipation mechanism. The blood flow measurement device according to any one of claims 1 to 5 , wherein the heat load application unit is a heat application unit that applies heat to a skin surface of a measurement target site. A measurement region that contacts the skin surface of the measurement target site when measuring blood flow, and
A skin surface thermometer for measuring the skin surface temperature of the measurement target part placed in the measurement region;
An environmental thermometer for measuring the environmental temperature;
A nuclear thermometer that measures the core temperature of the measurement object;
A thermal load application unit that applies a thermal load to the measurement target site when measuring blood flow;
After the application of the thermal load, a temperature change measurement unit that measures the temperature change of the skin temperature of the measurement target site through the skin surface thermometer;
Based on the environmental temperature, the core temperature, and the temperature change after the application of the thermal load is completed, a signal processing unit that calculates the blood flow volume of the measurement target site,
A blood flow measurement device comprising: means for notifying a measurement result relating to a blood flow calculated by calculation. A process for measuring the ambient temperature;
A process for measuring the nuclear body temperature to be measured;
A process of applying a thermal load to the measurement target site when measuring blood flow;
A process for measuring an initial value of the skin surface temperature of the measurement target part placed in a measurement region in contact with the skin surface of the measurement target part; and
After the application of the thermal load, a process of measuring a change in the skin surface temperature of the measurement target site;
A blood flow measurement method comprising: processing of calculating a blood flow volume of the measurement target region based on an environmental temperature, a nuclear body temperature, and a temperature change of a skin temperature after the application of the heat load is completed.

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