Blood purification device

Abstract

A blood purification device (1) comprises: a blood purifier (3) capable of purifying blood; a blood circuit (2) having an arterial-side blood circuit (21) and a venous-side blood circuit (22); an impedance measuring unit (5) which has an oscillator (53) that applies an alternating current voltage between an arterial-side electrode (51) provided to the arterial-side blood circuit (21) and a venous-side electrode (52) provided to the venous-side blood circuit (22), and which is capable of measuring a frequency characteristic of impedance between the arterial-side electrode (51) and the venous-side electrode (52); and a puncture determination unit (72) that determines whether a patient has been punctured correctly on the basis of the frequency characteristic of the measured impedance, the blood purification device further comprising a voltage control unit (70) that controls the amplitude of the alternating current voltage applied by the oscillator (53) such that the amplitude of an alternating current flowing when the alternating current voltage is applied from the oscillator (53) is at or above a preset lower threshold value.

Description

Blood purification device

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

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in a blood circuit that extracorporeally circulates a patient's blood, and dialysis fluid is introduced into or withdrawn from the dialyzer to perform blood purification treatment.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

[0003] U.S. Patent Application Publication No. 2008 / 0195021

[0004] In blood purification treatment, it is necessary to puncture an arterial side puncture needle and a venous side puncture needle into 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] Therefore, an object of the present invention is to provide a blood purification device capable of accurately determining whether a puncture into a patient is being performed normally.

[0006] A blood purification device according to an embodiment of the present invention includes a blood purifier capable of purifying blood, an arterial side blood circuit having an arterial side puncture needle that can be punctured into a patient attached to its tip and a base end connected to the blood purifier, a venous side blood circuit having a venous side puncture needle that can be punctured into a patient attached to its tip and a base end connected to the blood purifier, a blood circuit for extracorporeally circulating a patient's blood, an oscillator that applies an alternating voltage between an arterial side electrode provided in the arterial side blood circuit and a venous side electrode provided in the venous side blood circuit, an impedance measurement unit capable of measuring the frequency characteristics of the impedance between the arterial side electrode and the venous side electrode, and a puncture determination unit that determines whether a patient has been normally punctured based on the frequency characteristics of the impedance measured by the impedance measurement unit. Further, a voltage control unit is provided that controls the amplitude of the alternating voltage applied by the oscillator so that the amplitude of the alternating current flowing when the alternating voltage is applied from the oscillator is not less than a preset lower limit threshold value.

[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.

[0008] This is a schematic diagram of a blood purification device according to one embodiment of the present invention. This is a diagram showing an example of arterial and venous electrodes. This is a diagram showing an example of arterial and venous electrodes. This is a diagram showing an example of arterial and venous electrodes. This is a diagram showing an example of impedance frequency characteristics (impedance distribution). This is a diagram showing an example of impedance frequency characteristics (impedance distribution). This is the control flow during puncture determination. This is the control flow for impedance measurement.

[0009] [Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the attached 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 the dialysate supply, 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 is equipped with an impedance measurement unit 5 capable of measuring the frequency characteristics of the impedance of the liquid in the blood circuit. The impedance measurement 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 2A, the arterial electrode 51 and the venous electrode 52 consist of cylindrical conductors connected to the flexible tube that constitutes the blood circuit 2. For example, the arterial electrode 51 and the venous electrode 52 are electrically connected to the oscillator 53 by attaching the clips of the clipped 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, and any shape that can apply voltage to the liquid flowing in the blood circuit 2 is acceptable, 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 2B, or electrode structures with two metal plates sandwiching the flexible tube constituting the blood circuit 2, as shown in Figure 2C. 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 current voltage between the arterial electrode 51 and the venous electrode 52. The oscillator 53 is also configured to appropriately change the frequency of the applied alternating current voltage from low frequencies (e.g., several tens of Hz) to high frequencies (e.g., several MHz). The amplitude of the alternating current voltage applied by the oscillator 53 is controlled by the voltage control unit 70, which will be described later.

[0016] The impedance meter 54 measures the impedance between the arterial electrode 51 and the venous electrode 52 when an AC voltage is applied by the oscillator 53. More specifically, it measures the AC current that flows when an AC voltage is applied by the oscillator 53, and determines the impedance based on the applied AC voltage and the measured AC current. In this embodiment, the impedance meter 54 is configured to output the value of the measured AC current. By changing the frequency of the AC voltage applied by the oscillator 53 and measuring the impedance with the impedance meter 54, the impedance for each frequency can be measured. The impedance between the arterial electrode 51 and the venous electrode 52 measured by the impedance meter 54 changes depending on whether or not a puncture is performed on the patient.

[0017] (Control device 6) The blood purification device 1 is equipped with a control device 6 that controls blood purification treatment, etc. The control device 6 has a control unit 7 and a storage unit 8. The control unit 7 is realized by appropriately combining computing elements, memory, storage device, software, interface, etc. The storage unit 8 is realized by memory and 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) 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 flowing when an AC voltage is applied from the oscillator 53 is equal to or greater than a preset lower threshold. In this embodiment, the voltage control unit 70 constantly monitors the AC current measured by the impedance meter 54 when measuring impedance, and when the amplitude of the AC voltage is less than a preset lower limit, it performs a process to increase the amplitude of the AC voltage by a predetermined value. This prevents the AC current from becoming too small and being affected by noise (i.e., the S / N ratio from decreasing), which would reduce the accuracy of impedance measurement, and improves the accuracy of impedance measurement. As a result, it becomes possible to accurately determine whether the patient has been properly punctured.

[0019] In this example, the alternating current was measured using the impedance meter 54, but this is not the only option. A current measuring instrument separate from the impedance meter 54 may also be provided for measuring the alternating current. In this case, for example, the current may be converted to voltage using a resistor for measurement.

[0020] Furthermore, if the AC current does not increase even when the applied AC voltage is increased, it is likely that some kind of malfunction has occurred. Since increasing the applied AC voltage too much can cause electric shock, the voltage control unit 70 should stop 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, and should notify the system of the abnormality using the abnormality notification unit 73, which will be described later.

[0021] Furthermore, the voltage control unit 70 may perform a process to control the amplitude of the AC voltage applied by the oscillator 53 so that the amplitude of the measured AC current is less than or equal to a preset upper limit. This makes it possible to suppress problems such as electric shock even if the AC current becomes too large for some reason.

[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 Response 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 measuring instrument 54. The frequency response acquisition unit 71 acquires the impedance measurement results from the impedance measuring instrument 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 3A, the impedance distribution is a plot of the resistive and capacitive components of impedance for 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 3A to the distribution shown in Figure 3B. 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 been 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 determination unit 72, normal frequency characteristic memory unit 83) The normal frequency characteristic memory unit 83 stores the impedance frequency characteristics when the puncture to the patient is performed normally (hereinafter referred to as the normal impedance frequency characteristics). 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 characteristic 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 frequency characteristics of the impedance match those of a normal patient. 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 3A and 3B 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 relationship between the resistive component and the capacitive component 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 if we let Rref(x) be the resistive component and Cref(x) be the capacitive component in the normal frequency characteristics, and Rcur(x) be the resistive component and Ccur(x) be the resistive component in the measured frequency characteristics, then we can obtain the following relationships (1) and (2). In equations (1) and (2) below, a and b are the lowest and highest frequencies output by the oscillator 53.

[0031]

[0032]

[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 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] (Abnormality Notification Unit 73) The abnormality notification unit 73 notifies the user or administrator of the abnormality when the puncture determination unit 72 determines that there is a mismatch. 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 threshold for voltage. The abnormality notification unit 73 may notify of the abnormality by sound or light, for example, by using a buzzer or warning light, or by displaying a message notifying of the abnormality 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 determination) Figure 4 shows the control flow during puncture determination. The control flow in Figure 4 is executed when determining whether the puncture has been 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 interrupts the process.

[0038] If the result is determined to be No (N) in step S12, the impedance is measured using the impedance measuring instrument 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 is determined to be No (N) in step S18, the process returns to step S12 and the impedance measurement continues. If the result is determined to be Yes (Y) in step S18, 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. Furthermore, 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 3A and 3B) 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 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 equal to or greater than a preset lower threshold. This makes it possible to suppress problems such as the AC current being too small when measuring impedance, 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] In addition, in the blood purification device 1 according to the present embodiment, when the amplitude of the alternating 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 applying the alternating voltage by the oscillator 53. Thereby, it is possible to suppress problems such as electric shock caused by the amplitude of the applied alternating voltage becoming too large.

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

[0045] (Modification) In the above embodiment, the case where the amplitude of the alternating voltage applied is controlled by constantly monitoring the amplitude of the alternating current during impedance measurement has been described. However, the present invention is not limited to this. For example, during impedance measurement, the amplitude of the alternating voltage may be controlled by the voltage control unit 70 at a predetermined time interval.

[0046] Also, the amplitude control of the alternating voltage by the voltage control unit 70 may be performed only when a predetermined condition is satisfied. For example, the amplitude control of the alternating voltage by the voltage control unit 70 may be configured to be performed when any one of the following conditions (a) to (f) is satisfied. (a) When the type of fluid in the blood circuit 2 changes. (b) When the presence or absence of patient puncture changes. (c) When the blood concentration changes due to ultrafiltration or fluid replacement. (d) When the arterial side electrode 51 and the venous side electrode 52 are detached. (e) When the patient moves. (f) When the state of the fluid in the blood circuit 2 changes due to a process transition or the like.

[0047] Regarding the change in the type of fluid in the blood circuit 2 in (a), the change in blood concentration in (c), and the change in the state of the fluid in (f) under the above conditions, it is possible to detect by using a sensor that measures the hematocrit value of the fluid in the blood circuit 2 or by performing process management of the blood purification treatment or the like. Regarding the presence or absence of puncture in (b), it is possible to detect by process management of the blood purification treatment, the operation of the user, or the like. Further, regarding the attachment and detachment of the electrode in (d), it is possible to detect by the operation of the user or the like. Regarding the body movement of the patient in (e), it is possible to detect by using a body movement sensor that detects the body movement of the patient or by the operation of the user or the like.

[0048] (Summary of Embodiment) Next, regarding the technical idea grasped from the embodiments described above, it will be described by referring to the reference numerals and the like in the embodiments. However, each reference numeral and the like in the following description are not limited to the members and the like that specifically show the components in the claims in the embodiments.

[0049] [1] A blood purification device (3) capable of purifying blood, an arterial blood circuit (21) having an arterial puncture needle (211) that can puncture a patient attached to the tip and a base end connected to the blood purification device (3), and a venous puncture needle (221) that can puncture a patient attached to the tip and a base end connected to the blood purification device (3). A blood circuit (2) for extracorporeal circulation of the patient's blood, an arterial electrode (51) provided in the arterial blood circuit (21), and an oscillation for applying an alternating voltage between the arterial electrode (51) and the venous electrode (52) provided in the venous blood circuit (22). An impedance measuring unit (5) 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) for determining whether the patient is normally punctured based on the frequency characteristics of the impedance measured by the impedance measuring unit (5). Further, a voltage control unit (70) for controlling the amplitude of the alternating voltage applied by the oscillator (53) so that the amplitude of the alternating current flowing when the alternating voltage is applied from the oscillator (53) is not less than a preset lower threshold value. Blood purification device (1).

[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) becomes equal to or greater than a preset upper threshold for voltage.

[0051] [3] 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, as described in [1].

[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.

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

Claims

1. A blood purification device comprising: a blood purifier capable of purifying blood; an arterial blood circuit having an arterial puncture needle attached to its tip and connected to the blood purifier at its base, and a venous blood circuit having a venous puncture needle attached to its tip and connected to the blood purifier at its base, for extracorporeal circulation of the patient's blood; an impedance measuring unit having an oscillator that applies an alternating current 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; 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 a voltage control unit that controls the amplitude of the alternating current applied by the oscillator so that the amplitude of the alternating current flowing when the alternating current voltage is applied from the oscillator is greater than or equal to a preset lower threshold.

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

3. The blood purification apparatus according to claim 1, wherein 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.

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