Blood purification device

Abstract

This blood purification device (1) comprises: a blood circuit (2) that extracorporeally circulates the blood of a patient; a blood purifier (3) that is provided in the blood circuit (2) and is capable of purifying the blood; an impedance measurement unit (5) that is capable of measuring the frequency characteristics of the impedance of a liquid in the blood circuit (2); a normal-time frequency characteristics storage unit (83) that stores normal-time impedance frequency characteristics corresponding to the liquid flowing through the blood circuit (2); and a liquid determination unit (72) that compares the impedance frequency characteristics measured by the impedance measurement unit (5) with the normal-time impedance frequency characteristics stored in the normal-time frequency characteristics storage unit (83), and determines whether or not the impedance characteristics match.

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in a blood circuit that extracorporeally circulates a patient's blood, and dialysis fluid is introduced into or withdrawn from the dialyzer to perform a blood purification treatment. The blood purification treatment is carried out through various steps. Examples of the steps of the blood purification treatment include a priming step of filling the blood circuit with physiological saline, a blood purification step of performing blood purification treatment, a blood return step of returning the blood in the blood circuit to the patient, and a drainage step of draining the physiological saline introduced into the blood circuit after blood return.

[0003] As prior art document information related to the invention of this application, there is Patent Document 1.

[0004] U.S. Patent Application Publication No. 2008 / 0195021

[0005] However, in conventional blood purification devices, there is a risk of human error, for example, proceeding to the next blood purification step even though the filling of physiological saline is not completed in the priming step. In order to enhance safety more, a technology that can confirm whether the preparation for starting the next step is ready has been desired.

[0006] Therefore, an object of the present invention is to provide a blood purification device with improved safety.

[0007] A blood purification device according to an embodiment of the present invention includes a blood circuit that extracorporeally circulates a patient's blood, a blood purifier provided in the blood circuit that can purify blood, an impedance measurement unit that can measure the frequency characteristics of the impedance of the liquid in the blood circuit, a normal frequency characteristic storage unit that stores the frequency characteristics of the normal impedance according to the liquid flowing in the blood circuit, and a liquid determination unit that compares the frequency characteristics of the impedance measured by the impedance measurement unit with the frequency characteristics of the normal impedance stored in the normal frequency characteristic storage unit to determine whether they match.

[0008] Furthermore, a blood purification device according to one embodiment comprises a blood circuit for circulating the patient's blood outside the body, a blood purifier provided in the blood circuit capable of purifying the blood, an impedance measuring unit capable of measuring the impedance of the liquid in the blood circuit at a predetermined frequency, a normal frequency characteristic storage unit that stores the impedance at the predetermined frequency under normal conditions corresponding to the liquid flowing through the blood circuit, and a liquid determination unit that compares the impedance at the predetermined frequency measured by the impedance measuring unit with the impedance at the predetermined frequency under normal conditions stored in the normal frequency characteristic storage unit and determines whether they match.

[0009] According to the present invention, a blood purification device with improved safety can be provided.

[0010] 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 an explanatory diagram showing specific examples of the liquid in the blood circuit and the presence or absence of puncture during process transitions. the control flow during the transition to the next process.

[0011] [Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

[0012] (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.

[0013] 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.

[0014] 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.

[0015] (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.

[0016] 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.

[0017] 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 a low frequency (e.g., several tens of Hz) to a high frequency (e.g., several MHz).

[0018] 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. 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 the type of fluid in the blood circuit 2 and whether or not the patient is punctured.

[0019] (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 frequency characteristic acquisition unit 71, a liquid determination unit 72, a process transition limiting unit 73, and an abnormality notification unit 74.

[0020] (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 controls the frequency of the oscillator 53, acquires the impedance measurement results from the impedance measuring instrument 54, and stores them in the measurement result storage unit 81. 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.

[0021] 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, 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 type of fluid in the blood circuit 2 and the state of puncture on the patient. Therefore, by comparing the impedance distribution under normal conditions in any given process with the measured impedance distribution, it is possible to determine whether the process is in a normal state or not. Note that the vertical and horizontal axes of the impedance distribution may be swapped, and the resistive component of impedance may be on the vertical axis and the capacitive component on the horizontal axis.

[0022] (Liquid detection unit 72, normal frequency characteristic memory unit 83) The normal frequency characteristic memory unit 83 stores the frequency characteristics (impedance distribution) of the impedance under normal conditions according to the liquid flowing through the blood circuit 2. In this embodiment, the normal frequency characteristic memory unit 83 stores, for each step of the blood purification treatment, the frequency characteristics (impedance distribution) of the impedance under normal conditions according to the liquid flowing through the blood circuit and the puncture status (the state when the patient is not punctured, and the state when the patient is punctured under normal conditions).

[0023] The liquid 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.

[0024] In this embodiment, the liquid determination unit 72 is configured to compare the frequency characteristics of the impedance measured by the impedance measurement unit 5 with the frequency characteristics of the impedance under normal conditions at the next step, stored in the normal frequency characteristics storage unit 83, when transitioning from any step of blood purification therapy to the next step, and to determine if they match. This configuration makes it possible to confirm whether the system is in a normal state at the start of the next step, and if it is not in a normal state, it is possible to restrict the start of the next step (see the step transition restriction unit 73 described later), thereby improving safety.

[0025] More specifically, as shown in Figure 4A, when transitioning from the priming process, in which saline solution is filled into the blood circuit 2 before the start of blood purification therapy, to the puncture process, in which the arterial puncture needle 211 and venous puncture needle 221 are inserted into the patient, it is necessary that the blood circuit 2 is filled with saline solution and that the patient has not been punctured. Therefore, the frequency characteristics of the impedance measured during the process transition (measured frequency characteristics) are compared with the frequency characteristics of the impedance under normal conditions, when the liquid in the blood circuit 2 is saline solution and no puncture has occurred (normal frequency characteristics), to confirm whether they match.

[0026] Furthermore, as shown in Figure 4B, when transitioning from the puncture process to the blood purification process, that is, at the start of blood purification therapy, the blood circuit 2 must be filled with saline solution and contain some blood, and the patient must be punctured. Therefore, the frequency characteristics of the impedance measured during the process transition (measured frequency characteristics) are compared with the frequency characteristics of the impedance under normal conditions when the fluid in the blood circuit 2 is saline solution and blood, and puncture is performed (normal frequency characteristics), to confirm whether they match.

[0027] Furthermore, as shown in Figure 4C, when transitioning from the blood return process, in which the blood in the blood circuit 2 is returned to the patient and the blood circuit 2 is filled with physiological saline, to the blood circuit AV connection process, in which the arterial puncture needle 211 and the venous puncture needle 221 are connected, it is necessary that the blood circuit 2 is filled with physiological saline, contains some blood, and is punctured into the patient. Therefore, the frequency characteristics of the impedance measured during the process transition (measured frequency characteristics) are compared with the frequency characteristics of the impedance under normal conditions (normal frequency characteristics) when the liquid in the blood circuit 2 is physiological saline and puncture is performed, to confirm whether they match.

[0028] Furthermore, as shown in Figure 4D, when transitioning from the blood circuit AV connection process to the blood circuit draining process, which involves draining the fluid from blood circuit 2, it is necessary that blood circuit 2 is filled with saline solution and that the patient is not being punctured. Therefore, the frequency characteristics of the impedance measured during the process transition (measured frequency characteristics) are compared with the frequency characteristics of the impedance under normal conditions (normal frequency characteristics) when the fluid in blood circuit 2 is saline solution and there is no puncture, and it is confirmed that they match.

[0029] Furthermore, as shown in Figure 5A, when transitioning from the blood circuit draining process to the washing and disinfection process, it is necessary that the fluid in blood circuit 2 is drained and that the patient is not being punctured. Therefore, the frequency characteristics of the impedance measured during the process transition (measured frequency characteristics) are compared with the frequency characteristics of the impedance under normal conditions (normal frequency characteristics) when there is no fluid in blood circuit 2 (air) and no puncture is performed, and it is confirmed that they match.

[0030] Furthermore, as shown in Figure 5B, when transitioning from the blood purification process to the circulating process during withdrawal, in which the arterial puncture needle 211 and the venous puncture needle 221 are connected and blood is circulated within the blood circuit 2 when the patient withdraws midway, it is necessary that the fluid in the blood circuit 2 is blood and that the patient is not being punctured. Therefore, the frequency characteristics of the impedance measured during the process transition (measured frequency characteristics) are compared with the frequency characteristics of the impedance under normal conditions (normal frequency characteristics) when the fluid in the blood circuit 2 is blood and there is no puncture, to confirm whether they match.

[0031] Furthermore, as shown in Figure 5C, when transitioning from the post-disconnection puncture process, where the patient is punctured after disconnection, to the blood purification process, it is necessary that the fluid in the blood circuit 2 is blood and that the patient is being punctured. Therefore, the frequency characteristics of the impedance measured during the process transition (measured frequency characteristics) are compared with the frequency characteristics of the impedance under normal conditions (normal frequency characteristics) when the fluid in the blood circuit 2 is blood and puncture is performed, to confirm whether they match.

[0032] The liquid detection unit 72 determines whether the frequency characteristics of the measured impedance match those of the normal impedance by comparing the impedance distributions shown in Figure 3. More specifically, the liquid detection 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.

[0033] Furthermore, the liquid determination unit 72 may perform the 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 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.

[0034]

[0035]

[0036] 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 impedance under normal conditions. 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 impedance under normal conditions. Note that the determination method by the liquid determination unit 72 is not limited to the above, and determination may be made using other pattern matching methods, etc.

[0037] In this embodiment, the measurement of the impedance frequency characteristics and the determination by the liquid determination unit 72 were performed when transitioning from the current process to the next process (immediately before transitioning to the next process). However, the measurement of the impedance frequency characteristics and the determination by the liquid determination unit 72 may be performed not only when transitioning to the next process, but also while any process is in progress. In this case, the liquid determination unit 72 will determine whether the measured impedance frequency characteristics match the normal impedance frequency characteristics in the current process.

[0038] (Process transition restriction unit 73) The process transition restriction unit 73 restricts the start of the next process when the liquid determination unit 72 determines that they do not match, and releases the restriction on the start of the next process when the liquid determination unit 72 determines that they match. As a result, if the liquid in the blood circuit 2 or the puncture state is not in a normal state for the next process (i.e., if the preparation for the next process is not complete), the next process will not be started, thereby improving safety.

[0039] (Anomaly Notification Unit 74) When the liquid determination unit 72 determines that the results do not match, the abnormality notification unit 74 notifies the user or administrator of the abnormality. The abnormality notification unit 74 may, for example, notify the administrator of the abnormality by sound or light using a buzzer or warning light, display an abnormality notification message on a display unit provided in the blood purification device 1, or notify the administrator of the abnormality by sending an email or the like.

[0040] (Control Flow at the Time of Transition to the Next Process) FIG. 6 shows the control flow at the time of transition to the next process. The control flow in FIG. 6 is executed immediately before transitioning to the next process from an arbitrary process.

[0041] First, in step S1, the frequency characteristic acquisition unit 71 uses the impedance measurement unit 5 to measure the impedance while changing the frequency of the voltage applied by the oscillator 53. The impedance measured for each frequency is stored in the measurement result storage unit 81. Then, in step S2, the frequency characteristic acquisition unit 71 obtains the frequency characteristics of the impedance (the impedance distribution in FIG. 3) based on the measurement results of the impedance for each frequency stored in the measurement result storage unit 81. The obtained frequency characteristics of the impedance are stored in the measurement frequency characteristic storage unit 82.

[0042] Then, in step S3, the liquid determination unit 72 compares the frequency characteristics of the impedance obtained in step S2 with the frequency characteristics of the impedance under normal conditions in the next process stored in the normal time frequency characteristic storage unit 83 to determine whether they match. If it is determined as No (N) in step S3, in step S4, the process transition restriction unit 73 restricts the start of the next process. And in step S5, the abnormality notification unit 74 notifies of the abnormality. Then, it returns to step S1.

[0043] If it is determined as Yes (Y) in step S3, in step S6, the process transition restriction unit 73 releases the restriction on the start of the next process, and the next process is started. Then, the process ends.

[0044] (Operations and Effects of the Embodiment) As described above, in the blood purification device 1 according to the present embodiment, an impedance measurement unit 5 capable of measuring the frequency characteristics of the impedance of the liquid in the blood circuit 2, a normal time frequency characteristic storage unit 83 that stores the frequency characteristics of the impedance under normal conditions according to the liquid flowing in the blood circuit 2, a liquid determination unit 72 that compares the frequency characteristics of the impedance measured by the impedance measurement unit 5 with the frequency characteristics of the impedance under normal conditions stored in the normal time frequency characteristic storage unit 83 to determine whether they match, are provided.

[0045] This makes it possible to check whether the preparation for the next step is complete, and if the preparation is not complete, it becomes possible to perform processes such as restricting the start of the next step. As a result, it becomes possible to further improve the safety of blood purification treatment.

[0046] Also, in the blood purification device 1, during each step of the blood purification treatment, the normal frequency characteristic storage unit 83 stores the frequency characteristics of the impedance at normal times according to the liquid flowing through the blood circuit 2 and the presence or absence of puncture of the patient in that step. When transitioning from an arbitrary step to the next step of the blood purification treatment, the liquid determination unit 72 compares the frequency characteristics of the impedance measured by the impedance measurement unit 5 with the frequency characteristics of the impedance at normal times in the next step stored in the normal frequency characteristic storage unit 83 to determine whether they match. This makes it possible to determine whether the preparation for the next step is complete, taking into account the presence or absence of puncture, and improves safety further.

[0047] Further, in the blood purification device 1, there is a step transition restriction unit 73 that restricts the start of the next step when the liquid determination unit 72 determines that they do not match, and releases the restriction on the start of the next step when the liquid determination unit 72 determines that they match. This makes it possible to start the next step only when the preparation for the next step is complete, and improves safety further.

[0048] Also, in the blood purification device 1, the liquid determination unit 72 makes a determination using the mutual correlation relationship between the resistance component and the capacitance component that make up the frequency characteristics of the impedance. Thereby, it is possible to accurately determine whether the measured frequency characteristics of the impedance match the frequency characteristics of the impedance at normal times.

[0049] Furthermore, in the blood purification device 1, 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 meter 54 that measures the impedance between the arterial electrode 51 and the venous electrode 52 at each frequency. This makes it possible to easily measure the frequency characteristics of the impedance.

[0050] (Modification) In the above embodiment, the frequency characteristics of the measured impedance were compared with the frequency characteristics of the impedance under normal conditions to determine whether the next step was ready. However, the invention is not limited to this, and it is also possible to make the determination using the impedance of a single pre-set frequency. In this case, the impedance measurement unit 5 only needs to be able to measure the impedance of the liquid in the blood circuit 2 at a predetermined frequency. The normal frequency characteristic memory unit 83 should store the impedance at a predetermined frequency under normal conditions corresponding to the liquid flowing in the blood circuit 2. The liquid determination unit 72 should then compare the impedance at a predetermined frequency measured by the impedance measurement unit 5 with the impedance at a predetermined frequency under normal conditions stored in the normal frequency characteristic memory unit 83 to determine if they match. It is also possible to make the determination using impedances at multiple frequencies, not just one frequency.

[0051] (Summary of Embodiments) Next, the technical concept understood from the embodiments described above will be described using the reference numerals, etc., from the embodiments. However, the reference numerals, etc., in the following description are not limited to the components in the claims that are specifically shown in the embodiments.

[0052] [1] A blood purification device (1) comprising: a blood circuit (2) for circulating the patient's blood extracorporeally; a blood purifier (3) provided in the blood circuit (2) capable of purifying the blood; an impedance measuring unit (5) capable of measuring the frequency characteristics of the impedance of the liquid in the blood circuit (2); a normal frequency characteristic storage unit (83) that stores the frequency characteristics of the impedance under normal conditions corresponding to the liquid flowing through the blood circuit (2); and a liquid determination unit (72) that compares the frequency characteristics of the impedance measured by the impedance measuring unit (5) with the frequency characteristics of the impedance under normal conditions stored in the normal frequency characteristic storage unit (83) and determines whether they match.

[0053] [2] The blood purification apparatus (1) according to [1], wherein the normal frequency characteristic memory unit (83) stores the frequency characteristics of the normal impedance according to the liquid flowing through the blood circuit (2) in each step of the blood purification treatment and whether or not the patient is punctured, and the liquid determination unit (72) compares the frequency characteristics of the impedance measured by the impedance measurement unit (5) with the frequency characteristics of the normal impedance in the next step stored in the normal frequency characteristic memory unit (83) to determine if they match.

[0054] [3] The blood purification apparatus (1) according to [2], further comprising a process transition restriction unit (73) that restricts the start of the next process when the liquid determination unit (72) determines that they do not match, and releases the restriction on the start of the next process when the liquid determination unit (72) determines that they match.

[0055] [4] The blood purification apparatus (1) described in [1], wherein the liquid determination unit (72) makes a determination using the mutual correlation relationship between the resistive component and the capacitive component that constitute the frequency characteristics of the impedance.

[0056] [5] The blood purification device (1) according to [1], wherein the blood circuit (2) comprises an arterial blood circuit (21) with an arterial puncture needle (211) that can be used to puncture a patient attached to its tip, and a venous blood circuit (22) with a venous puncture needle (221) that can be used to puncture a patient attached to its tip, and the impedance measuring unit (5) comprises an arterial electrode (51) provided on the arterial blood circuit (21), a venous electrode (52) provided on the venous blood circuit (22), an oscillator (53) that applies an alternating current voltage between the arterial electrode (51) and the venous electrode (52) and can switch the frequency of the alternating current voltage, and an impedance measuring device (54) that measures the impedance between the arterial electrode (51) and the venous electrode (52) at each frequency.

[0057] [6] A blood purification device (1) comprising: a blood circuit (2) for circulating the patient's blood extracorporeally; a blood purifier (3) provided in the blood circuit (2) capable of purifying the blood; an impedance measuring unit (5) capable of measuring the impedance of the liquid in the blood circuit (2) at a predetermined frequency; a normal frequency characteristic storage unit (83) that stores the impedance at the predetermined frequency under normal conditions corresponding to the liquid flowing in the blood circuit (2); and a liquid determination unit (72) that compares the impedance at the predetermined frequency measured by the impedance measuring unit (5) with the impedance at the predetermined frequency under normal conditions stored in the normal frequency characteristic storage unit (83) and determines whether they match.

[0058] 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.

[0059] 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 71...Frequency characteristic acquisition unit 72...Liquid determination unit 73...Process transition limiting unit 74...Anomaly 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 circuit for circulating a patient's blood outside the body; a blood purifier capable of purifying the blood provided in the blood circuit; an impedance measuring unit capable of measuring the frequency characteristics of the impedance of the liquid in the blood circuit; a normal frequency characteristic storage unit that stores the frequency characteristics of the impedance under normal conditions corresponding to the liquid flowing through the blood circuit; and a liquid determination unit that compares the frequency characteristics of the impedance measured by the impedance measuring unit with the frequency characteristics of the impedance under normal conditions stored in the normal frequency characteristic storage unit to determine if they match.

2. The blood purification apparatus according to claim 1, wherein the normal frequency characteristic memory unit stores the frequency characteristics of the normal impedance for each step of the blood purification treatment, according to the liquid flowing through the blood circuit and whether or not a puncture is performed on the patient, and the liquid determination unit, when transitioning from any step of the blood purification treatment to the next step, compares the frequency characteristics of the impedance measured by the impedance measurement unit with the frequency characteristics of the normal impedance for the next step stored in the normal frequency characteristic memory unit to determine if they match.

3. The blood purification apparatus according to claim 2, further comprising a process transition restriction unit that restricts the start of the next process when the liquid determination unit determines that the liquids do not match, and releases the restriction on the start of the next process when the liquid determination unit determines that the liquids do match.

4. The blood purification apparatus according to claim 1, wherein the liquid determination unit makes a determination using the mutual correlation relationship between the resistive component and the capacitive component that constitute the frequency characteristics of the impedance.

5. The blood purification apparatus according to claim 1, wherein the blood circuit comprises an arterial blood circuit with an arterial puncture needle attached to its tip that can be used to puncture a patient, and a venous blood circuit with a venous puncture needle attached to its tip that can be used to puncture a patient, and the impedance measuring unit comprises an arterial electrode provided in the arterial blood circuit, a venous electrode provided in the venous blood circuit, an oscillator that applies an alternating current voltage between the arterial electrode and the venous electrode and can switch the frequency of the alternating current voltage, and an impedance measuring instrument that measures the impedance between the arterial electrode and the venous electrode at each frequency.

6. A blood purification device comprising: a blood circuit for circulating a patient's blood extracorporeally; a blood purifier capable of purifying the blood provided in the blood circuit; an impedance measuring unit capable of measuring the impedance of the liquid in the blood circuit at a predetermined frequency; a normal frequency characteristic storage unit that stores the impedance at the predetermined frequency under normal conditions corresponding to the liquid flowing through the blood circuit; and a liquid determination unit that compares the impedance at the predetermined frequency measured by the impedance measuring unit with the impedance at the predetermined frequency under normal conditions stored in the normal frequency characteristic storage unit to determine if they match.

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