Blood purification device

Abstract

To provide a blood purification device that can accurately determine whether a venipuncture has been performed correctly in a patient. [Solution] The blood purification device 1 comprises a blood purifier 3 capable of purifying blood, a blood circuit 2 having an arterial blood circuit 21 and a venous blood circuit 22, an impedance measuring unit 5 having an oscillator 53 that applies an AC voltage between an arterial electrode 51 provided on the arterial blood circuit 21 and a venous electrode 52 provided on the venous blood circuit 22, and capable of measuring the frequency characteristics of the impedance between the arterial electrode 51 and the venous electrode 52, and a puncture determination unit 72 that determines whether the patient has been punctured normally based on the measured impedance frequency characteristics, and further comprises a voltage control unit 70 that controls the amplitude of the AC voltage applied by the oscillator 53 so that the amplitude of the AC current that flows when the AC voltage is applied from the oscillator 53 is greater than or equal to a preset lower threshold.

Description

Technical Field

[0001] The present invention relates to a blood purification device.

Background Art

[0002] Generally, in blood purification treatments such as dialysis treatment, a dialyzer is provided in a blood circuit that extracorporeally circulates a patient's blood, and dialysis fluid is introduced into or withdrawn from the dialyzer to perform blood purification treatment. As prior art document information related to the invention of this application, there is Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In blood purification treatment, it is necessary to puncture an arterial side puncture needle and a venous side puncture needle in a patient, collect the patient's blood from the arterial side puncture needle, perform blood purification treatment while extracorporeally circulating it in a blood circuit, and then return the purified blood to the patient from the venous side puncture needle. Therefore, it is desired to accurately determine whether the puncture of the arterial side puncture needle or the venous side puncture needle is being performed normally and improve safety.

[0005] [[ID=�8]] Therefore, an object of the present invention is to provide a blood purification device capable of accurately determining whether a puncture in a patient is being performed normally.

Means for Solving the Problems

[0006] A blood purification device according to one embodiment of the present invention comprises a blood purifier capable of purifying blood, an arterial blood circuit having an arterial puncture needle attached to its tip and its base connected to the blood purifier, and a venous blood circuit having a venous puncture needle attached to its tip and its base connected to the blood purifier, for circulating the patient's blood extracorporeally, an impedance measuring unit having an oscillator that applies an AC voltage between an arterial electrode provided in the arterial blood circuit and a venous electrode provided in the venous blood circuit, and capable of measuring the frequency characteristics of the impedance between the arterial electrode and the venous electrode, and a puncture determination unit that determines whether the patient has been properly punctured based on the frequency characteristics of the impedance measured by the impedance measuring unit, and further comprises a voltage control unit that controls the amplitude of the AC voltage applied by the oscillator so that the amplitude of the AC current flowing when the AC voltage is applied from the oscillator is greater than or equal to a preset lower threshold. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a blood purification device that can accurately determine whether a puncture has been performed correctly on a patient. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of a blood purification device according to one embodiment of the present invention. [Figure 2] (a) to (c) are diagrams showing examples of arterial and venous electrodes. [Figure 3] (a) and (b) are diagrams showing examples of the frequency characteristics (impedance distribution) of impedance. [Figure 4] This is the control flow for determining whether a puncture was performed. [Figure 5] This is the control flow for impedance measurement. [Modes for carrying out the invention]

[0009] [Embodiment] Embodiments of the present invention will be described below with reference to the accompanying drawings.

[0010] (Overall configuration of blood purification device 1) Figure 1 is a schematic diagram of the blood purification device 1 according to this embodiment. As shown in Figure 1, the blood purification device 1 comprises a blood circuit 2 for circulating the patient's blood outside the body, and a blood purifier 3 provided in the blood circuit 2 that is capable of purifying the blood.

[0011] The blood circuit 2 consists of a flexible tube through which a fluid such as blood flows. The blood circuit 2 has an arterial blood circuit 21 with an arterial puncture needle 211 attached to its tip that can be used to puncture a patient, and a venous blood circuit 22 with a venous puncture needle 221 attached to its tip that can be used to puncture a patient. The proximal ends of the arterial blood circuit 21 and the proximal ends of the venous blood circuit 22 are connected to the blood purifier 3. The arterial blood circuit 21 is equipped with a blood pump 23, which is a squeezing type pump for pumping the fluid in the blood circuit 2. The venous blood circuit 22 is equipped with a gas-liquid separator 24 for separating air bubbles from the fluid flowing through the blood circuit 2.

[0012] The blood purifier 3, also called a dialyzer, has a blood inlet port 3a, a blood outlet port 3b, a dialysate inlet port 3c, and a drain outlet port 3d. The proximal end of the arterial blood circuit 21 is connected to the blood inlet port 3a, and the proximal end of the venous blood circuit 22 is connected to the blood outlet port 3b. The dialysate inlet port 3c is connected to a dialysate inlet line 41 extending from the main body of the device 4, and the drain outlet port 3d is connected to a drain outlet line 42 extending from the main body of the device 4. Inside the blood purifier 3, multiple hollow fibers are housed, and the blood flows inside the hollow fibers, while the dialysate flows outside the hollow fibers. Numerous tiny pores are formed in the hollow fibers, allowing impurities in the blood to permeate into the dialysate. Furthermore, by discharging more drain fluid than dialysate, water is removed from the blood. Although not shown in the diagram, the blood circuit 2 may be equipped with a bubble detector, a pressure sensor, or the like as appropriate.

[0013] (Impedance measurement unit 5) The blood purification device 1 includes an impedance measuring unit 5 capable of measuring the frequency characteristics of the impedance of the liquid in the blood circuit. The impedance measuring unit 5 includes an arterial electrode 51 provided in the arterial blood circuit 21, a venous electrode 52 provided in the venous blood circuit 22, an oscillator 53 that applies an AC voltage between the arterial electrode 51 and the venous electrode 52 and can switch the frequency of the AC voltage, and an impedance measuring instrument 54 that measures the impedance between the arterial electrode 51 and the venous electrode 52 at each frequency.

[0014] Here, the arterial electrode 51 is provided in the arterial blood circuit 21 between the blood pump 23 and the arterial puncture needle 211. The venous electrode 52 is provided in the venous blood circuit 22 between the gas-liquid separator 24 and the venous puncture needle 221. As shown in Figure 2(a), the arterial electrode 51 and the venous electrode 52 consist of cylindrical conductors connected to the flexible tubes that constitute the blood circuit 2. For example, the arterial electrode 51 and the venous electrode 52 are electrically connected to the oscillator 53 by attaching clips from clip-equipped wires extending from the oscillator 53 to the arterial electrode 51 and the venous electrode 52. The specific shapes of the arterial electrode 51 and the venous electrode 52 are not limited to those shown in the figure; they can be any shape that can apply voltage to the liquid flowing in the blood circuit 2, and the electrode structure may not directly touch the liquid. More specifically, the arterial electrode 51 and the venous electrode 52 may be, for example, cylindrical electrode structures provided to surround the flexible tube constituting the blood circuit 2, as shown in Figure 2(b), or electrode structures with two metal plates sandwiching the flexible tube constituting the blood circuit 2, as shown in Figure 2(c). By making the arterial electrode 51 and the venous electrode 52 electrode structures that do not directly come into contact with the liquid, obstruction of the flow of liquid in the blood circuit 2 can be suppressed, and metals with low biocompatibility can be used as electrodes. Note that the electrode structures shown are merely examples, and the electrode structures of the arterial electrode 51 and the venous electrode 52 can be changed as appropriate.

[0015] The oscillator 53 applies an alternating voltage between the arterial side electrode 51 and the venous side electrode 52. Also, the oscillator 53 is configured to be able to appropriately change the frequency of the applied alternating voltage from a low frequency (for example, several tens of Hz) to a high frequency (for example, several MHz). The amplitude of the alternating voltage applied by the oscillator 53 is controlled by a voltage control unit 70 described later.

[0016] The impedance measuring device 54 measures the impedance between the arterial side electrode 51 and the venous side electrode 52 when an alternating voltage is applied by the oscillator 53. More specifically, it measures the alternating current flowing when an alternating voltage is applied by the oscillator 53, and obtains the impedance based on the applied alternating voltage and the measured alternating current. In the present embodiment, the impedance measuring device 54 is configured to be able to output the value of the measured alternating current. By changing the frequency of the alternating voltage applied by the oscillator 53 and performing impedance measurement with the impedance measuring device 54, the impedance for each frequency can be measured. The impedance between the arterial side electrode 51 and the venous side electrode 52 measured by the impedance measuring device 54 changes depending on whether or not the patient has been punctured.

[0017] (Control device 6) The blood purification device 1 includes a control device 6 that controls blood purification treatment and the like. The control device 6 has a control unit 7 and a storage unit 8. The control unit 7 is realized by appropriately combining an arithmetic element, a memory, a storage device, software, an interface, and the like. The storage unit 8 is realized by a memory or a storage device. The control unit 7 has a voltage control unit 70, a frequency characteristic acquisition unit 71, a puncture determination unit 72, and an abnormality notification unit 73.

[0018] (Voltage control unit 70) When the voltage control unit 70 controls the amplitude of the AC voltage applied by the oscillator 53 such that the amplitude of the AC current flowing when the AC voltage is applied from the oscillator 53 is equal to or greater than a preset lower threshold value. In the present embodiment, the voltage control unit 70 constantly monitors the AC current measured by the impedance measuring device 54 when measuring the impedance, and when the amplitude of the AC voltage is less than the preset lower threshold value, the voltage control unit 70 performs a process of increasing the amplitude of the AC voltage by a predetermined value. As a result, it is possible to prevent the AC current from becoming too small and being affected by noise (that is, the S / N ratio decreases), and the measurement accuracy of the impedance is improved. As a result, it becomes possible to accurately determine whether the patient has been punctured normally.

[0019] Here, the AC current is measured using the impedance measuring device 54. However, the present invention is not limited to this, and a current measuring device for measuring the AC current may be provided separately from the impedance measuring device 54. In this case, for example, the current may be converted into a voltage using a resistor and measured.

[0020] If the AC current does not increase even when the amplitude of the applied AC voltage is increased, it is considered that some malfunction has occurred. Since there is also a risk of electric shock if the amplitude of the applied AC voltage is made too large, when the amplitude of the AC voltage applied by the oscillator 53 becomes equal to or greater than a preset upper threshold value for voltage, the voltage control unit 70 stops the application of the AC voltage by the oscillator 53 and may notify an abnormality by an abnormality notification unit 73 described later.

[0021] Furthermore, the voltage control unit 70 may perform a process of controlling the amplitude of the AC voltage applied by the oscillator 53 such that the amplitude of the measured AC current is equal to or less than a preset upper limit value. As a result, even when the AC current becomes too large for some reason, malfunctions such as electric shock can be suppressed.

[0022] Furthermore, the initial value of the amplitude of the AC voltage applied by the oscillator 53 when measuring impedance may be set according to the fluid in the blood circuit 2 (blood, saline solution, or air). In this case, the initial value to be adopted can be selected, for example, according to the blood purification treatment process. In this case, it is advisable to set the initial value of the amplitude of the AC voltage applied by the oscillator 53 in advance for each blood purification treatment process and store it in the memory unit 8. Then, when measuring impedance, it is advisable to extract the initial value corresponding to the current blood purification treatment process from the memory unit 8 and control the oscillator 53 to apply the AC voltage with the amplitude of the extracted initial value.

[0023] (Frequency characteristic acquisition unit 71) The frequency response acquisition unit 71 performs a frequency response acquisition process to acquire the frequency response of the impedance based on the impedance measured for each frequency by the impedance meter 54. The frequency response acquisition unit 71 acquires the impedance measurement results from the impedance meter 54 while controlling the frequency of the oscillator 53 and stores them in the measurement result storage unit 81. At this time, the amplitude of the AC voltage applied by the oscillator 53 is controlled by the voltage control unit 70. If the amplitude of the AC voltage is changed by the voltage control unit 70 during impedance measurement, it is advisable to repeat the impedance measurement with the changed amplitude of the AC voltage. Then, the frequency response acquisition unit 71 obtains the frequency response of the impedance based on the impedance measurement results for each frequency stored in the measurement result storage unit 81. The obtained impedance frequency response is stored in the measurement frequency response storage unit 82.

[0024] In this embodiment, an impedance distribution, which shows the relationship between the resistive and capacitive components of impedance, is used as the frequency characteristic of impedance. More specifically, as shown in Figure 3(a), the impedance distribution is a plot of the resistive and capacitive components of impedance at each measured frequency, with the resistive component value on the horizontal axis and the capacitive component value on the vertical axis. This impedance distribution (i.e., the frequency characteristic of impedance) changes depending on the state of puncture in the patient. Therefore, by comparing the impedance distribution when puncture is performed normally with the measured impedance distribution, it is possible to determine whether puncture has been performed normally in the patient.

[0025] For example, if the arterial electrode 51 or venous electrode 52 is not properly inserted for any reason, the impedance frequency characteristics will change from the initial distribution shown in Figure 3(a) to the distribution shown in Figure 3(b). Therefore, by determining whether the change in the impedance frequency characteristics exceeds a certain level, it is possible to determine that the arterial puncture needle 211 or venous puncture needle 221 has not properly inserted into the blood vessel. Note that the vertical and horizontal axes of the impedance distribution may be swapped, and the resistance component of the impedance may be on the vertical axis and the capacitance component on the horizontal axis.

[0026] (Puncture detection unit 72, normal frequency characteristic memory unit 83) The normal frequency characteristics memory unit 83 stores the impedance frequency characteristics (hereinafter referred to as the normal impedance frequency characteristics) when the puncture to the patient is performed normally. It is known that the impedance frequency characteristics also change depending on the type of fluid flowing through the blood circuit 2, so it is more desirable to store the normal impedance frequency characteristics (impedance distribution) for each fluid flowing through the blood circuit 2 in the normal frequency characteristics memory unit 83.

[0027] The puncture determination unit 72 compares the frequency characteristics of the impedance measured by the impedance measurement unit 5 (i.e., the frequency characteristics of the impedance stored in the measured frequency characteristics storage unit 82 by the frequency characteristics acquisition unit 71) with the frequency characteristics of the impedance under normal conditions stored in the normal frequency characteristics storage unit 83, and determines whether they match.

[0028] In this embodiment, the puncture determination unit 72 is configured to measure the frequency characteristics of the impedance at predetermined time intervals and to determine whether the measured impedance frequency characteristics match those of a normal impedance. This configuration makes it possible to detect, for example, cases where the puncture becomes abnormal due to body movement during blood purification therapy, thereby improving safety.

[0029] The puncture determination unit 72 compares the impedance distributions shown in Figures 3(a) and 3(b) to determine whether the frequency characteristics of the measured impedance match those of the normal impedance. More specifically, the puncture determination unit 72 determines that the two do not match when the change in the frequency characteristics of the measured impedance (the difference between the two) relative to the frequency characteristics of the normal impedance exceeds a certain level.

[0030] Furthermore, the puncture determination unit 72 may make a determination by utilizing the mutual correlation between the resistive and capacitive components that constitute the frequency characteristics of the impedance. For example, if we let R be the resistive component, C be the capacitive component, and x be the frequency at the time of measurement, and let Rref(x) be the resistive component and Cref(x) be the capacitive component in the normal frequency characteristics, and let Rcur(x) be the resistive component and Ccur(x) be the capacitive component in the measured frequency characteristics, then the following relationships (1) and (2) can be obtained. In equations (1) and (2) below, a and b are the lowest and highest frequencies output by the oscillator 53.

[0031]

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[0032]

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[0033] The closer the values ​​of R and C obtained in equations (1) and (2) above are to 0, the closer the frequency characteristics of the measured impedance are to the frequency characteristics of the normal impedance. Therefore, if either or both of the values ​​of R and C obtained in equations (1) and (2) above exceed a preset threshold, it can be determined that the frequency characteristics of the measured impedance do not match the frequency characteristics of the normal impedance. Note that the determination method by the puncture determination unit 72 is not limited to the above, and determination may be made using other pattern matching methods, etc.

[0034] (Anomaly Notification Unit 73) The abnormality notification unit 73 notifies the user or administrator of the abnormality when the puncture determination unit 72 determines that the results do not match. The abnormality notification unit 73 also notifies of the abnormality when the voltage control unit 70 determines that the amplitude of the AC voltage applied by the oscillator 53 has exceeded a preset upper voltage threshold. The abnormality notification unit 73 may notify of the abnormality by sound or light, such as using a buzzer or warning light, or by displaying an abnormality notification message on a display unit provided in the blood purification device 1, or by sending an email or the like to the administrator.

[0035] (Control flow during puncture detection) Figure 4 shows the control flow during puncture evaluation. The control flow in Figure 4 is executed when determining whether the puncture was performed correctly. For example, the control flow in Figure 4 is executed at predetermined time intervals during blood purification therapy.

[0036] First, in step S1, the frequency characteristic acquisition unit 71 uses the impedance measurement unit 5 to measure the impedance between the arterial electrode 51 and the venous electrode 52. In step S1, as shown in Figure 5, first, in step S11, an AC voltage is applied from the oscillator 53 between the arterial electrode 51 and the venous electrode 52, with the frequency set to the lowest frequency and the amplitude set to an initial value (for example, an initial value for each process). Then, in step S12, the voltage control unit 70 determines whether the amplitude of the AC current measured when the AC voltage was applied is less than a lower threshold. The specific method for measuring the amplitude of the AC current is not particularly limited.

[0037] If the result in step S12 is Yes (Y), in step S13 the voltage control unit 70 controls the amplitude of the AC voltage applied by the oscillator 53 to increase by a predetermined value. Then, in step S14 the voltage control unit 70 determines whether the amplitude of the AC voltage is equal to or greater than the upper limit threshold for voltage. If the result in step S14 is No (N), the process returns to step S12. If the result in step S14 is Yes (Y), in step S15 the abnormality notification unit 73 notifies of the abnormality and then the process is interrupted.

[0038] If the result in step S12 is No (N), the impedance is measured using the impedance meter 54 in step S16. The measured impedance value is stored in the measurement result storage unit 81. Then, in step S17, the frequency is increased by a predetermined value, and in step S18, it is determined whether the frequency is greater than the highest frequency. If the result in step S18 is No (N), the process returns to step S12 and the impedance measurement continues. If the result in step S18 is Yes (Y), the process returns and proceeds to step S2 in Figure 4.

[0039] Although not shown in Figure 5, a step may be added to reduce the amplitude of the AC voltage when the measured AC current exceeds an upper threshold. Additionally, a step may be added to remeasure the impedance when the voltage is changed by the voltage control unit 70.

[0040] Returning to Figure 4, in step S2, the frequency response acquisition unit 71 obtains the impedance frequency characteristics (impedance distribution shown in Figures 3(a) and (b)) based on the impedance measurement results for each frequency stored in the measurement result storage unit 81. The obtained impedance frequency characteristics are stored in the measurement frequency characteristics storage unit 82.

[0041] Subsequently, in step S3, the puncture determination unit 72 compares the impedance frequency characteristics obtained in step S2 with the normal impedance frequency characteristics stored in the normal frequency characteristics storage unit 83 to determine if they match. At this time, the normal impedance frequency characteristics should be selected to correspond to the type of fluid in the blood circuit 2 (for example, those set for each process). If Yes (Y) is determined in step S3, the process ends without issuing an abnormality notification. If No (N) is determined in step S3, the abnormality notification unit 73 issues an abnormality notification in step S4. After that, the process ends.

[0042] (Operation and Effects of the Embodiment) As described above, the blood purification device 1 according to this embodiment is equipped with a voltage control unit 70 that controls the amplitude of the AC current applied by the oscillator 53 so that the amplitude of the AC current flowing when an AC voltage is applied from the oscillator 53 is equal to or greater than a preset lower threshold. This makes it possible to suppress problems such as the AC current being too small during impedance measurement, which prevents accurate measurement of impedance, and to accurately measure the frequency characteristics of impedance. As a result, it becomes possible to accurately determine whether the puncture has been performed correctly on the patient, thereby improving safety.

[0043] Furthermore, in the blood purification device 1 according to this embodiment, the voltage control unit 70 stops the application of AC voltage by the oscillator 53 when the amplitude of the AC voltage applied by the oscillator 53 exceeds a preset upper voltage threshold. This makes it possible to suppress problems such as electric shock caused by the amplitude of the applied AC voltage becoming too large.

[0044] Furthermore, in the blood purification device 1 according to this embodiment, the voltage control unit 70 controls the amplitude of the AC voltage applied by the oscillator 53 so that the amplitude of the AC current is less than or equal to a preset upper limit. This makes it possible to suppress malfunctions such as electric shock even if an excessive current flows for some reason.

[0045] (modified version) In the above embodiment, we have described a case in which the amplitude of the AC voltage applied is controlled by constantly monitoring the amplitude of the AC current during impedance measurement. However, the embodiment is not limited to this, and for example, the voltage control unit 70 may be configured to control the amplitude of the AC voltage at predetermined time intervals during impedance measurement.

[0046] Furthermore, the voltage control unit 70 may be configured to control the amplitude of the AC voltage only when certain conditions are met. For example, the voltage control unit 70 may be configured to control the amplitude of the AC voltage when any of the following conditions (a) to (f) are met. (a) When the type of fluid in blood circuit 2 changes (b) When the presence or absence of a patient's puncture changes (c) When blood concentration changes due to fluid removal or replacement, (d) When the arterial electrode 51 and the venous electrode 52 are attached to and detached (e) When the patient moves (f) When the state of the fluid in blood circuit 2 changes due to process transitions, etc.

[0047] Furthermore, under the above conditions, the changes in the type of fluid in blood circuit 2 (a), the changes in blood concentration (c), and the changes in the state of the fluid (f) can be detected by using a sensor that measures the hematocrit value of the fluid in blood circuit 2, or by performing process control of the blood purification treatment. The presence or absence of puncture (b) can be detected by process control of the blood purification treatment or by user operation. In addition, electrode attachment and detachment (d) can be detected by user operation. Patient movement (e) can be detected by using a patient movement sensor or by user operation.

[0048] (Summary of the embodiments) Next, the technical concept understood from the embodiments described above will be described using the reference numerals and other symbols from the embodiments. However, the reference numerals and other symbols in the following description are not limited to the components in the claims that are specifically shown in the embodiments.

[0049] [1] A blood circuit (2) for extracorporeal circulation of the patient's blood, comprising: a blood purifier (3) capable of purifying blood; an arterial blood circuit (21) with an arterial puncture needle (211) attached to its tip and its proximal end connected to the blood purifier (3); and a venous blood circuit (22) with a venous puncture needle (221) attached to its tip and its proximal end connected to the blood purifier (3); and an oscillator that applies an alternating current voltage between an arterial electrode (51) provided on the arterial blood circuit (21) and a venous electrode (52) provided on the venous blood circuit (22). A blood purification device (1) comprising: an impedance measuring unit (5) having (53) and capable of measuring the frequency characteristics of the impedance between the arterial side electrode (51) and the venous side electrode (52); a puncture determination unit (72) that determines whether the patient has been properly punctured based on the frequency characteristics of the impedance measured by the impedance measuring unit (5); and a voltage control unit (70) that controls the amplitude of the AC voltage applied by the oscillator (53) so that the amplitude of the AC current that flows when an AC voltage is applied from the oscillator (53) is greater than or equal to a preset lower threshold.

[0050] [2] The blood purification apparatus (1) according to [1], wherein the voltage control unit (70) stops applying the AC voltage by the oscillator (53) when the amplitude of the AC voltage applied by the oscillator (53) exceeds a preset upper threshold for voltage.

[0051] [3] The blood purification apparatus (1) according to [1], wherein the voltage control unit (70) controls the amplitude of the AC voltage applied by the oscillator (53) so that the amplitude of the AC current is less than or equal to a preset upper limit.

[0052] Although embodiments of the present invention have been described above, the embodiments described above do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention. In addition, the present invention can be implemented with appropriate modifications without departing from its spirit. [Explanation of symbols]

[0053] 1…Blood purification device 2…Blood circuit 21…Arterial blood circuit 211…Arterial side puncture needle 22…Venous blood circuit 221... Venous puncture needle 3… Blood purifier 5…Impedance measurement section 51...Arterial side electrode 52…Venous side electrode 53…Oscillator 54…Impedance meter 6...Control device 7…Control Unit 70...Voltage control unit 71...Frequency response acquisition unit 72...Puncture determination unit 73... Abnormal Information Department 8...Storage section 81...Measurement result storage section 82…Measurement frequency characteristic storage section 83...Normal frequency response memory unit

Claims

1. A blood purifier capable of purifying blood, A blood circuit for extracorporeal circulation of the patient's blood has an arterial blood circuit with an arterial puncture needle attached to its tip and its base connected to the blood purifier, and a venous blood circuit with a venous puncture needle attached to its tip and its base connected to the blood purifier, An impedance measuring unit having an oscillator that applies an AC voltage between the arterial electrode provided in the arterial blood circuit and the venous electrode provided in the venous blood circuit, and capable of measuring the frequency characteristics of the impedance between the arterial electrode and the venous electrode, The system includes a puncture determination unit that determines whether the patient has been properly punctured based on the frequency characteristics of the impedance measured by the impedance measurement unit, Furthermore, the system includes a voltage control unit that controls the amplitude of the AC voltage applied by the oscillator so that the amplitude of the AC current flowing when an AC voltage is applied from the oscillator is equal to or greater than a preset lower threshold. Blood purification device.

2. The voltage control unit stops the application of the AC voltage by the oscillator when the amplitude of the AC voltage applied by the oscillator exceeds a preset upper voltage threshold. The blood purification device according to claim 1.

3. The voltage control unit controls the amplitude of the AC voltage applied by the oscillator so that the amplitude of the AC current is less than or equal to a preset upper limit. The blood purification device according to claim 1.

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