JP2019074430A - Ultrasonic flowmeter and blood purifying device - Google Patents

Abstract

To provide an ultrasonic flowmeter which is used in a blood purifying device and maintains the accuracy of measurement even when measuring different types of liquid.SOLUTION: The ultrasonic flowmeter comprises ultrasonic transducers 10A, 10B used in a blood purifying device 100A, and a flow rate measuring circuit 20A for measuring the flow rate of a liquid on the basis of an ultrasonic signal. The flow rate measuring circuit 20A includes a transmission unit 21 for transmitting an ultrasonic signal, a reception unit 22 for receiving an ultrasonic signal, a determination unit 24 for determining which step the blood purifying device 100A is in, a storage unit 25 for storing a plurality of correction parameters in advance that correspond to the type of liquid, and a flow rate calculation unit 26 for calculating a corrected flow rate on the basis of the transmitted ultrasonic signal, the ultrasonic signal received by the reception unit, and the correction parameter stored in the storage unit 25 that corresponds to the type of liquid flowing in a step determined by the determination unit 24.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ultrasonic flowmeter used in a blood purification apparatus.

  In a blood purification apparatus used for treatment such as hemodialysis, plasma exchange, adsorption therapy, a blood pump is used to flow a fluid such as blood or priming solution through a blood conduit to which the blood purification means is connected. Since the liquid does not necessarily flow according to the flow rate, an ultrasonic flowmeter is used to grasp the actual flow rate (actual flow rate) (see Patent Documents 1 and 2).

  By the way, in the blood purification apparatus, there is a priming process for washing the blood conduit and the like before the start of the treatment, a blood removal process for removing blood from the patient, a treatment process for treating using the blood purification means, Various processes, such as a blood process, are performed (refer patent document 3).

In these steps, the type of fluid flowing through the blood conduit is different. For example, in the priming step, a priming solution such as a reverse filtration dialysate reversely filtered by a dialyzer (blood purification means) or a saline flows, and in the treatment step, blood mainly flows. In addition, in the blood removal step and the blood return step, a liquid in which physiological saline or reverse filtration dialysate and blood are mixed flows.
As described above, in the blood purification apparatus, it is necessary to continuously measure the flow rate of the liquid of different types through each process.

JP 2005-253768 A JP 2008-023269 A JP, 2014-188219, A

  When the type of liquid is different, measurement using an ultrasonic flowmeter causes a problem that the measurement error may increase depending on the type of liquid because the specific gravity and viscosity of the liquid are different.

  Therefore, an object of the present invention is to provide an ultrasonic flowmeter which is used in a blood purification apparatus and maintains measurement accuracy even when measuring different types of liquids.

  The present invention is an ultrasonic flowmeter for use in a blood purification apparatus, comprising a blood conduit and a blood pump for flowing liquid in the blood conduit, and performing a plurality of steps of different types of liquid flowing in the blood conduit. Measuring the flow rate of the liquid based on an ultrasonic transducer mounted in contact with the outside of the blood conduit through which the liquid flows and transmitting and receiving ultrasonic signals, and the ultrasonic signals transmitted and received by the ultrasonic transmitter and receiver A flow rate measuring circuit, the flow rate measuring circuit transmitting a ultrasonic signal to the ultrasonic transducer, a receiving unit receiving an ultrasonic signal from the ultrasonic transducer, and a liquid Storage unit for storing in advance a plurality of correction parameters according to the type of the subject, a determination unit for determining which one of the plurality of steps the blood purification apparatus is in, and an ultrasonic signal transmitted by the transmission unit And the receiving unit A flow rate calculating unit that calculates a corrected flow rate based on the ultrasonic wave signal received by the controller and the correction parameter stored in the storage unit according to the type of liquid flowing in the process determined by the determination unit; And an ultrasonic flowmeter.

  The blood purification apparatus further includes a control unit that switches and controls the plurality of processes, and the determination unit performs process determination by receiving process information to be performed by the blood purification apparatus from the control unit. Is preferred.

  Further, the plurality of steps include a changing step in which the type of the flowing liquid gradually changes, and the flow rate calculating unit determines that the step determined by the determining unit is the changing step. It is preferable to calculate the corrected flow rate by switching the correction parameter in accordance with the change in the type of liquid in the above.

  Further, the ultrasonic flowmeter includes at least a pair of the ultrasonic transducers arranged at a predetermined distance in the flow direction of the liquid flowing through the blood conduit, and the ultrasonic transducers include: It is preferable to transmit and receive ultrasonic signals obliquely to the flow direction of the liquid.

  The present invention also relates to a blood purification apparatus comprising any of the ultrasonic flowmeters described above, a blood conduit, and a blood pump for flowing liquid through the blood conduit.

  According to the ultrasonic flowmeter of the present invention, it is determined which process is to be performed by the blood purification apparatus, and the flow rate at which the measured flow rate is corrected using the correction parameter corresponding to the type of liquid flowing through the blood conduit The calculation accuracy can be maintained even if the type of liquid to be measured changes by calculating.

It is an explanatory view showing the composition of a 1st embodiment of the present invention. It is a figure which shows schematic structure of the blood purification apparatus. It is a figure which shows the priming process implemented with a blood purification apparatus. It is a figure which shows the priming process implemented with a blood purification apparatus. It is a figure which shows the blood removal process implemented with a blood purification apparatus. It is a figure which shows the treatment process implemented with a blood purification apparatus. It is a figure which shows the blood return process implemented with a blood purification apparatus. It is explanatory drawing which shows the structure of 2nd Embodiment of this invention.

  Hereinafter, preferred embodiments of the ultrasonic flowmeter and blood purification apparatus of the present invention will be described with reference to the drawings. The present invention will be described by way of example using a blood purifier that purifies blood of renal failure patients and drug addicts and performs excess blood removal in blood.

First Embodiment
FIG. 1 is an explanatory view showing the configuration of a blood purification apparatus 100A according to a first embodiment of the present invention and an ultrasonic flowmeter 1A used in the apparatus, and FIG. 2 shows a schematic configuration of the blood purification apparatus 100A. FIG.
First, the configuration of the blood purification apparatus 100A will be described with reference to FIG.

  The blood purification apparatus 100A includes a dialyzer 110 as a blood purification unit, a blood conduit 120, an ultrasonic flowmeter 1A disposed in the blood conduit 120, a dialysate conduit 140, a dialysate delivery unit 150, and control. And a unit 160.

  The dialyzer 110 includes a cylindrical container body 111 and a dialysis membrane (not shown) accommodated in the inside of the container body 111. The inside of the container body 111 is a blood side stream by the dialysis membrane. It is divided into a channel and a dialysate side channel (both not shown). The container body 111 is formed with a blood inlet 112 a and a blood outlet 112 b communicating with the blood conduit 120, and a dialysate inlet 113 a and a dialysate outlet 113 b communicating with the dialysate conduit 140.

  The blood conduit 120 has an arterial line 121, a venous line 122, a drug line 123, and a drainage line 124. Each of the artery side line 121, the vein side line 122, the drug line 123 and the drainage line 124 is mainly composed of a flexible tube having a flexibility allowing liquid to flow.

One end of the arterial line 121 is connected to the blood inlet 112 a of the dialyzer 110. In the artery side line 121, an artery side connection part 121a, an artery side air bubble detector 121b, a blood pump 130 and an ultrasonic flowmeter 1A described later are arranged.
The artery-side connection portion 121 a is disposed on the other end side of the artery-side line 121. A needle to be punctured in a blood vessel of a patient is connected to the arterial side connection portion 121a.
The artery-side air bubble detector 121 b detects the presence or absence of air bubbles in the tube.
The blood pump 130 is disposed downstream of the arterial air bubble detector 121 b in the arterial line 121. The blood pump 130 delivers the liquid inside the arterial line 121 by squeezing the tube constituting the arterial line 121 with a roller.

The ultrasonic flowmeter 1A is disposed upstream of the blood pump 130 in the arterial line 121. The ultrasonic flowmeter 1A includes ultrasonic transducers 10A and 10B that transmit and receive ultrasonic signals, and a flow measurement circuit 20A that measures the flow of liquid based on ultrasonic signals transmitted and received by the ultrasonic transmitter and receiver. To measure the flow rate of the fluid flowing through the arterial line 121 (see FIG. 1).
The ultrasonic flowmeter 1A may be attached at any position in the blood conduit 120, but in the present embodiment, the ultrasonic flowmeter 1A is attached on the upstream side of the blood pump 130 of the arterial line 121. By being attached to this position, the measurement error can be reduced because it is not easily affected by water removal and water injection by the dialyzer 110. Furthermore, it is desirable that the attachment portion of the ultrasonic flowmeter 1A be located upstream of the artery-side air bubble detector 121b and near the artery-side connection portion 121a. By attaching the measuring device to a portion near the blood vessel connection portion, it is possible to obtain a measurement value closer to the blood flow of the living body.

In the blood conduit 120 (artery side line 121), the flow direction of the liquid is substantially vertical so that air bubbles in the blood conduit 120 affecting the measurement of the flow rate do not stay at the site where the ultrasonic flowmeter 1A is attached. Will be held to be Further, it is desirable to dispose the upstream side in the flow direction of the liquid in the lower part and the downstream side in the upper part so that the bubbles can rise quickly, and in the present embodiment, of all the steps performed by the blood purification apparatus 100A. The upstream side and the downstream side may be determined based on the flow direction of the liquid (blood) in the treatment process requiring the longest time.
Details of the ultrasonic flowmeter 1A will be described later.

One end of the vein line 122 is connected to the blood outlet 112 b of the dialyzer 110. The vein-side connection part 122a, the vein-side air bubble detector 122b, the drip chamber 122c, and the vein-side clamp 122d are disposed in the vein-side line 122.
The vein side connection part 122a is arrange | positioned at the other end side of the vein side line. A needle to be punctured in a blood vessel of a patient is connected to the vein side connection part 122a.
The vein-side air bubble detector 122 b detects the presence or absence of air bubbles in the tube.
The drip chamber 122c is disposed upstream of the vein-side air bubble detector 122b. The drip chamber 122c stores a certain amount of blood in order to remove air bubbles mixed in the vein side line 122, coagulated blood and the like, and also to measure venous pressure.
The vein-side clamp 122 d is disposed downstream of the vein-side air bubble detector 122 b. The vein-side clamp 122 d is controlled according to the detection result of the air bubble by the vein-side air bubble detector 122 b and opens and closes the flow path of the vein side line 122.

  The drug line 123 supplies drugs necessary for hemodialysis to the arterial line 121. One end side of the drug line 123 is connected to a drug solution pump 123 a that delivers the drug, and the other end side is connected to the arterial line 121. Further, the drug line 123 is provided with a clamp means (not shown), and the flow path is closed by the clamp means except when injecting the drug. In the present embodiment, the other end side of the drug line 123 is connected to the downstream side of the ultrasonic flowmeter 1A in the arterial line 121.

  The drainage line 124 is connected to the drip chamber 122c. The drainage line clamp 124 a is disposed in the drainage line 124. The drainage line 124 is a line for draining the priming solution in the priming step described later.

  According to the dialyzer 110, the blood conduit 120, and the blood pump 130 described above, the blood taken from the artery of the subject (dialysis patient) flows through the arterial line 121 by the blood pump 130 and the blood side channel of the dialyzer 110 Introduced to The blood introduced into the dialyzer 110 is purified by the dialysate flowing through the dialysate conduit 140 described later via the dialysis membrane. The blood purified in the dialyzer 110 flows through the vein line 122 and is returned to the subject's vein.

  In this embodiment, the dialysate conduit 140 is constituted by a so-called closed volume control type dialysate line. The dialysate conduit 140 includes a dialysate supply line 141, a dialysate inlet line 142, a dialysate outlet line 143, and a dialysate drain line 144.

The dialysate delivery unit 150 includes a dialysate chamber 151, a bypass line 152, and a water removal / reverse filtration pump 153.
The dialysate chamber 151 is constituted by a hard container capable of containing a fixed volume (for example, 300 ml to 500 ml) of dialysate, and the inside of the container is partitioned by a soft diaphragm, and the liquid storage portion 151a and It is divided into the drainage accommodation part 151b.
The bypass line 152 connects the dialysate outlet line 143 and the dialysate drain line 144.

  The water removal / reverse filtration pump 153 is disposed in the bypass line 152. The water removal / reverse filtration pump 153 has a direction in which the dialysate in the bypass line 152 is caused to flow toward the dialysate drain line 144 (water removal direction) and a direction in which the dialysate is sent to the dialysate outlet line 143 (reverse filtration direction). It consists of a pump which drives to be able to send liquid

  A proximal end of the dialysate supply line 141 is connected to a dialysate supply device (not shown), and a distal end thereof is connected to the dialysate chamber 151. The dialysate supply line 141 supplies the dialysate to the fluid storage portion 151 a of the dialysate chamber 151.

  The dialysate introduction line 142 connects the dialysate chamber 151 and the dialysate introduction port 113 a of the dialyzer 110, and the dialysate contained in the fluid feed storage 151 a of the dialysate chamber 151 is the dialysate side flow path of the dialyzer 110. To introduce.

  The dialysate outlet line 143 connects the dialysate outlet 113 b of the dialyzer 110 and the dialysate chamber 151, and leads the dialysate discharged from the dialyzer 110 to the drainage storage portion 151 b of the dialysate chamber 151.

  A proximal end side of the dialysate drainage line 144 is connected to the dialysate chamber 151, and the dialysate drainage line 144 drains the drainage of the dialysate stored in the drainage storage portion 151b.

According to the above-described dialysate conduit 140 and dialysate delivery unit 150, the inside of the hard container constituting the dialysate chamber 151 is partitioned by a soft diaphragm, so that the dialysate from the dialysate chamber 151 is divided. And the amount of drainage collected in the dialysate chamber 151 (the drainage container 151b) can be equal.
As a result, in a state where the water removal / reverse filtration pump 153 is stopped, the flow rate of the dialysate introduced into the dialyzer 110 and the amount of dialysate (drain fluid) drawn out from the dialyzer 110 can be equal (see FIG. 3B).

  When the water removal / reverse filtration pump 153 is driven to feed in the reverse filtration direction, part of the drainage discharged from the dialysate chamber 151 passes through the bypass line 152 and the dialysate outlet line 143. It is again collected in the dialysate chamber 151. Therefore, the amount of dialysate discharged from the dialyzer 110 is the amount of dialysate flowing through the bypass line 152 from the amount recovered in the dialysate chamber 151 (ie, the amount of dialysate flowing through the dialysate introduction line 142). It becomes the quantity which reduced the quantity. As a result, the amount of dialysate discharged from the dialyzer 110 flows through the dialysate introduction line 142 by the amount of the dialysate (drainage) collected in the dialysate chamber 151 again through the bypass line 152. It will be less than the liquid flow rate. That is, when the water removal / reverse filtration pump 153 is driven to feed in the reverse filtration direction, a predetermined amount of dialysate is injected (reverse filtration) in the blood conduit 120 in the dialyzer 110 (see FIG. 3A). ).

  On the other hand, when the water removal / reverse filtration pump 153 is driven to feed in the water removal direction, the amount of dialysate flowing through the dialysate outlet line 143 is the dialysate recovered in the dialysate chamber 151. (Ie, the amount of dialysate flowing through the dialysate introduction line 142) plus the amount of dialysate flowing through the bypass line 152. As a result, the amount of dialysate flowing through the dialysate outlet line 143 is equal to the amount of dialysate (drainage) discharged to the dialysate drain line 144 through the bypass line 152. It will be more than the amount of dialysate flowing through. That is, when the water removal / reverse filtration pump 153 is driven to send liquid in the water removal direction, the dialyzer 110 removes water from the blood by a predetermined amount (see FIGS. 4 and 5).

The control unit 160 is configured by an information processing apparatus (computer), and controls the operation of the blood purification apparatus 100A by executing a control program.
Specifically, the control unit 160 controls operations of various pumps, clamps, and the like disposed in the blood conduit 120 and the dialysate conduit 140 to perform various processes performed by the hemodialysis apparatus 1, for example, a priming process, Execute blood removal process, treatment process, blood return process, etc.

  Various steps will be described below with reference to FIGS. 3 to 6.

The priming step shown in FIGS. 3A and 3B is a preparatory step of cleaning and purifying the dialyzer 110 and the blood conduit 120 and removing internal air.
In the present embodiment, as the priming step, the priming both sides step shown in FIG. 3A and the priming circulation step shown in FIG. 3B are sequentially performed.

  In the priming both-side process, as shown in FIG. 3A, the drainage line clamp 124a is opened and the vein clamp 122d is opened. In addition, the arterial side connection portion 121a and the vein side connection portion 122a are short-circuited.

The dialysate supply device (not shown) supplies and discharges the dialysate at a flow rate of, for example, 500 ml / min to the dialysate chamber 151, and sends the drainage / reverse filtration pump 153 in the reverse filtration direction. Activate. By setting the feed rate of the water removal / reverse filtration pump 153 to 400 ml / min, 400 ml / min of reverse filtration dialysate (priming fluid) is injected from the dialysate introduction line 142 through the dialyzer 110 into the blood conduit 120. Ru.
The blood pump 130 is operated so as to send the reverse filtration dialysate in the blood conduit 120 from the dialyzer 110 side to the arterial side connection portion 121a at a flow rate of 200 ml / min.
The reverse filtrate injected into the blood conduit 120 through the dialyzer 110 flows from the blood outlet 112b to the vein side line 122 at a flow rate of 200 ml / min and from the blood inlet 112a to the artery side line 121, Drain through drain line 124.

Subsequently, in the priming circulation step, as shown in FIG. 3B, the drainage line clamp 124a is switched from the open state to the closed state, and the dialysate supply device (not shown) sends 500 ml / min to the dialysate chamber 151. The water removal / reverse filtration pump 153 is stopped while the dialysate is being supplied and discharged in a volume. Further, the blood supply direction is changed from the artery side connection part 121 a side to the dialyzer 110 side, and the blood pump 130 is operated with a liquid supply amount of 200 ml / min.
Thus, the reverse filtration dialysate circulates in the blood conduit 120 at a flow rate of 200 ml / min.

Next, the blood removal step will be described with reference to FIG.
The blood removal step is a step in which the patient's blood is aspirated from both the artery side connection portion 121a and the vein side connection portion 122a after the puncture and the blood is filled in the artery side line 121 and the vein side line 122.

  In the blood removal step, as shown in FIG. 4, the arterial side connection portion 121a and the vein side connection portion 122a are respectively connected to a needle to be punctured by the patient's blood vessel, and the drainage line clamp 124a is in a closed state, the vein side. The clamp 122 d is in the open state.

The dialysate supply device (not shown) supplies and discharges the dialysate to the dialysate chamber 151 at a flow rate of 500 ml / min, and operates the water removal / reverse filtration pump 153 to send the solution in the water removal direction. Let By setting the feed amount of the water removal / reverse filtration pump 153 to 100 ml / min, water removal of 100 ml / min is performed in the dialyzer 110.
The blood pump 130 sends fluid from the side of the artery side connection part 121 a to the dialyzer 110 at a low flow rate of 40 to 50 ml / min. In this embodiment, it is 50 ml / min.
Into the dialyzer 110, reverse filtration dialysate flows at a flow rate of 50 ml / min from the blood inlet 112a, followed by blood, and reverse filtration dialysate at a flow rate of 50 ml / min from the blood outlet 112b, followed by blood. Do. In addition, the reverse filtration dialysate is drawn out from the dialysate outlet 113b. In this way, the inside of the dialyzer 110 and the inside of the blood conduit 120 are filled with blood.

Next, the treatment process will be described with reference to FIG.
The treatment process is performed for about 4 hours following the blood removal process, and the patient's blood introduced from the arterial connection 121a is purified by the dialyzer 110 through the arterial line 121 and through the venous line 122. It is returned to the patient from the venous connection 122a.

  In the treatment process, as shown in FIG. 5, the arterial side connection portion 121a and the vein side connection portion 122a are each connected to a needle that is punctured by the patient's blood vessel, and the drainage line clamp 124a is closed. , Vein side clamp 122d is in an open state.

The dialysate supply device (not shown) supplies and discharges the dialysate to the dialysate chamber 151 at a flow rate of 500 ml / min, and operates the water removal / reverse filtration pump 153 to send the solution in the water removal direction. Let By setting the feed amount of the water removal / reverse filtration pump 153 to 10 ml / min as an example, water removal of 10 ml / min is performed in the dialyzer 110.
The blood pump 130 gradually increases the flow rate from 40 to 50 ml / min to, for example, about 200 ml / min at the start of the treatment process, and delivers the blood from the artery side connection portion 121a to the dialyzer 110 side.
Blood flows into the dialyzer 110 at a flow rate of 200 ml / min from the blood inlet 112a, is dewatered at a flow rate of 10 ml / min, and is withdrawn at a flow rate of 190 ml / min from the blood outlet 112b. In addition, the reverse filtration dialysate is drawn out from the dialysate outlet 113b.

Next, the blood return process will be described with reference to FIG.
The blood return step is a step of returning the blood in the blood conduit 120 and in the dialyzer 110 to the patient's body after the treatment step is completed.

  In the blood return step, as shown in FIG. 6, the arterial side connection portion 121a and the vein side connection portion 122a are each connected to a needle to be punctured by the patient's blood vessel, and the drainage line clamp 124a is closed. State, vein side clamp 122 d is in an open state.

The dialysate supply device (not shown) supplies and discharges the dialysate at a flow rate of, for example, 500 ml / min to the dialysate chamber 151, and sends the drainage / reverse filtration pump 153 in the reverse filtration direction. Activate. By setting the feed amount of the water removal / reverse filtration pump 153 to 100 ml / min, water injection of 100 ml / min is performed in the dialyzer 110.
The blood pump 130 sends fluid from the dialyzer 110 side to the artery-side connection portion 121a at a low flow rate of 40 to 50 ml / min. In this embodiment, it is 50 ml / min.
The reverse filtration dialysate injected into the dialyzer 110 flows out from the blood inlet 112a and the blood outlet 112b at a flow rate of 50 ml / min, and flows toward the arterial side connection portion 121a and the vein side connection portion 122a. In this way, the blood in the dialyzer 110 and in the blood conduit 120 is returned to the patient's body.

As described above, in the plurality of steps performed by the blood purification apparatus 100A, the type of liquid flowing through the blood conduit 120 changes.
In the priming step, a reverse filtration dialysate flows as a priming solution, and in a blood removal step, a mixed solution of the reverse filtration dialysate and blood flows. Specifically, immediately after the start of blood removal, the backfiltration dialysate flows, then the liquid in which the backfiltration dialysate and blood are mixed flows, and then the blood flows. In the treatment process, blood mainly flows. In the blood return step, a mixture of blood and reverse filtration dialysate flows. Specifically, immediately after the start of blood return, blood flows, then a liquid in which the blood and the backfiltration dialysate are mixed flows, and then the backfiltration dialysate flows.
Also, although an example in which the reverse filtration dialysate is used in the priming step and the blood return step has been described, saline may be used.

Next, the ultrasonic flowmeter 1A according to the present embodiment will be described in detail with reference to FIG.
The ultrasonic flowmeter 1A includes a pair of ultrasonic transducers 10A and 10B, and a flow rate measurement circuit 20A that measures the flow rate of liquid, and is attached to the blood conduit 120 included in the blood purification apparatus 100A.

The ultrasonic transducers 10A and 10B each include a piezoelectric element 11 and a piezoelectric element cover 12. The ultrasonic transducers 10A and 10B are disposed at a predetermined distance with respect to the flow direction of the fluid flowing through the blood conduit 120 and are attached obliquely oppositely in contact with the outside of the blood conduit 120, and the ultrasonic signals are It can be sent and received.
Electrodes (not shown) are attached to both sides of the piezoelectric element 11 to convert the input electric signal into mechanical vibration, and convert the transmitted mechanical vibration into electric signal and output it. Can. The piezoelectric element 11 is embedded in a piezoelectric element cover 12 formed of a resin such as hard polyvinyl chloride, modified polyphenylene ether, polycarbonate, or acrylic. As a material of the piezoelectric element, piezoelectric ceramics such as lead zirconate titanate, piezoelectric thin films such as zinc oxide, piezoelectric polymer films such as vinylidene fluoride, and the like are applicable. In the present embodiment, lead zirconate titanate is used as the material of the piezoelectric element, and silver and platinum are used as the electrode.

  The flow rate measurement circuit 20A includes a transmission unit 21, a reception unit 22, a transmission / reception switching unit 23, a determination unit 24, a storage unit 25, and a flow rate calculation unit 26A. The flow rate measurement circuit 20A can measure the flow rate of the liquid based on the ultrasonic signals transmitted and received by the pair of ultrasonic transducers 10A and 10B.

The transmitting unit 21 is connected to the piezoelectric element 11 of the ultrasonic transducer 10A or 10B through the transmission / reception switching unit 23 to transmit an ultrasonic signal.
The receiving unit 22 is connected to the piezoelectric element 11 of the ultrasonic transducer 10A or 10B via the transmission / reception switching unit 23, receives an ultrasonic signal, and amplifies the received ultrasonic signal.
The transmission / reception switching unit 23 switches one of the ultrasonic transducers 10A and 10B to the transmitting unit 21 and the other to the receiving unit 22. Thereby, the transmission / reception switching unit 23 transmits the ultrasonic signal from the ultrasonic transducer 10A and transmits the ultrasonic signal from the ultrasonic transducer 10B when it is received by the ultrasonic transducer 10B. Then, it is possible to measure the propagation time when receiving by the ultrasonic transducer 10A.

The determination unit 24 determines which of the plurality of processes performed by the blood purification apparatus 100A.
For example, the determination unit 24 is connected to the control unit 160 of the blood purification apparatus 100A. Then, the determination unit 24 determines which process the blood purification apparatus 100A is in by receiving the process information from the control unit 160. Thus, the circuit configuration of the determination unit 24 can be simplified by acquiring process information from the blood purification apparatus 100A side.

The storage unit 25 stores a plurality of correction parameters according to the type of liquid flowing through the blood conduit 120 in each process performed by the blood purification apparatus 100A.
As described above, in the blood purification apparatus 100A, the liquid flowing in each process is different. Each correction parameter is determined by comparing measured flow rate and actual flow rate for each type of liquid such as reverse filtration dialysate (or physiological saline), blood, and mixed liquid of both, and it is determined in advance. A plurality of correction parameters are stored in the storage unit 25.

  The flow rate calculating unit 26 A stores the ultrasonic signal transmitted by the transmitting unit 21, the ultrasonic signal received by the receiving unit 22, and the storage unit 25 corresponding to the type of liquid flowing in the process determined by the determining unit 24. The flow rate is calculated based on the stored correction parameter.

  In the present embodiment, the corrected flow rate Q 'corrected with the flow rate Q and the correction parameter as follows is calculated using the propagation time difference method as an example. The ultrasonic transducers 10A and 10B transmit and receive ultrasonic signals obliquely to the flow direction of the liquid. Specifically, it is disposed opposite to the outside of the blood conduit 120 so that the angle between the direction in which the ultrasonic signal is transmitted and received and the flow direction of the liquid is a predetermined angle φ, and the ultrasonic signal is transmitted and received alternately. , Measuring the time required for the propagation of the ultrasound signal.

The time for propagation of the ultrasonic signal from the ultrasonic transducer 10A to 10B T _AB , the time for the propagation of the ultrasonic signal from the ultrasonic transducer 10B to 10 A T _BA , the distance for propagation of the ultrasonic signal L, The velocity of sound is C, and the flow velocity of the liquid in the blood conduit 120 is V.
With the fluid filled in the blood conduit 120, if the actual flow is zero, ie the flow velocity V is zero, then _TAB and _TBA are equal,
T _AB = T _BA = L / C (a)
It becomes.

As shown in FIG. 1, when the liquid flows from the ultrasonic transducer 10A side to the ultrasonic transducer 10B at a flow velocity V,
T _AB = L / (C + V cos φ) (b)
And
T _BA = L / (C−V cos φ) (c)
It becomes. Taking the difference between the propagation times T _AB and T _BA from the relationship between the equations (b) and (c), the square of the flow velocity V is sufficiently smaller than the square of the sound velocity C.
T _AB −T _BA = ( ² LV cos φ) / (C ² −V ² cos ² φ)
(( ² LV cos φ) / C ² (d)
It becomes. When the flow velocity V is obtained from the equation (d),
V = C ² / ( ² L cos φ) × (T _BA −T _AB ) (e)
It becomes. According to the equation (e), the flow velocity V can be calculated by measuring the propagation time of the ultrasonic signal.

In the equation (e), the flow rate Q can be calculated by multiplying the flow velocity V by the cross-sectional area A of the blood conduit 120.
Q = V × A (f)

Here, assuming that the correction parameter corresponding to the type of liquid to be measured is a, the correction flow rate Q ′ is
Q '= a × Q (g)
It can be calculated by

  According to the ultrasonic flowmeter 1A and the blood purification apparatus 100A of the first embodiment described above, the following effects can be obtained.

  (1) The ultrasonic flowmeter 1A, the ultrasonic transducers 10A and 10B, and the flow rate measurement circuit 20A, and the flow rate measurement circuit 20A transmits the ultrasonic signal, and the ultrasonic wave signal A receiving unit 22 to receive, a determining unit 24 that determines which process of the plurality of processes the blood purification apparatus 100A is in, a storage unit 25A that stores in advance a plurality of correction parameters respectively corresponding to the plurality of processes; And a flow rate calculating unit configured to calculate the flow rate based on the ultrasonic signals transmitted and received by the ultrasonic transducers 10A and 10B and the correction parameter. As a result, even if the type of liquid flowing through the blood conduit 120 changes as the process performed by the blood purification apparatus 100A is switched, the corrected flow rate Q 'corrected based on the correction parameter according to the type of liquid is changed. Since calculation is possible, measurement error can be reduced to maintain measurement accuracy.

  (2) The blood purification apparatus 100A includes the control unit 160 that switches and controls a plurality of processes with different types of liquid flowing through the blood conduit 120, and the determination unit 24 controls the process information performed by the blood purification apparatus 100A. The determination of the process is performed by receiving from 160. Thus, since the process information can be acquired from the blood purification apparatus 100A side, the circuit configuration of the determination unit 24 can be simplified.

  (3) The ultrasonic flowmeter 1A is provided with a pair of ultrasonic transducers 10A and 10B arranged at a predetermined distance in the flow direction of the liquid flowing through the blood conduit 120. As a result, the flow rate of the liquid can be measured with a simple configuration having a single measuring line, and the manufacturing cost can be reduced compared to the configuration with a plurality of measuring lines.

  (4) The blood conduit 120 (artery side line 121) is held so that the flow direction of the liquid is substantially vertical at the site where the ultrasonic flowmeter 1A is attached. As a result, air bubbles in the blood conduit 120 can be prevented from staying, so the influence of the air bubbles on the measurement of the flow rate can be reduced.

  (5) The blood conduit 120 (artery side line 121) is disposed so that the upstream side in the flow direction of the liquid is at the lower side and the downstream side is at the upper side in the region where the ultrasonic flowmeter 1A is attached. As a result, the air bubbles in the blood conduit 120 at the flow measurement site can rise quickly, so the influence of the air bubbles on the flow measurement can be reduced.

Second Embodiment
Next, a second embodiment will be described with reference to FIG.
FIG. 7 is an explanatory view showing the configuration of a blood purification apparatus 100B according to a second embodiment of the present invention and an ultrasonic flowmeter 1B used in the apparatus. About the same composition as a 1st embodiment, the same numerals are attached and explanation is omitted.

The blood purification apparatus 100B includes an ultrasonic flow meter 1B, a dialyzer 110, a blood conduit 120, a blood pump 130, a dialysate conduit 140, a dialysate delivery unit 150, a control unit 160, and a control substrate 170; Equipped with
Since each process implemented in blood purification device 100B is the same as that of a case of a 1st embodiment, explanation is omitted.

  The ultrasonic flowmeter 1B includes a pair of ultrasonic transducers 10A and 10B, and a flow measurement circuit 20B that measures the flow of liquid, and is attached to the blood conduit 120 provided in the blood purification apparatus 100B.

  The ultrasonic transducers 10A and 10B each include a piezoelectric element 11 and a piezoelectric element cover 12. The ultrasonic transducers 10A and 10B are disposed at a predetermined distance in the flow direction of the liquid flowing through the blood conduit 120. Also, the ultrasonic transducers 10A and 10B are attached to the same side in contact with the outside of the blood conduit 120, and can transmit and receive ultrasonic signals reflected by the blood conduit 120.

  The flow rate measurement circuit 20B includes a transmission unit 21, a reception unit 22, a transmission / reception switching unit 23, a determination unit 24, a storage unit 25, and a flow rate calculation unit 26B. The flow rate measurement circuit 20B can measure the flow rate of the liquid based on the ultrasonic signals transmitted and received by the pair of ultrasonic transducers 10A and 10B.

  The flow rate calculation unit 26 B stores the ultrasonic signal transmitted by the transmission unit 21, the ultrasonic signal received by the reception unit 22, and the storage unit 25 corresponding to the type of liquid flowing in the process determined by the determination unit 24. The flow rate is calculated based on the stored correction parameter.

The flow rate calculation unit 26B according to the present embodiment uses one correction parameter per process for the priming process and the treatment process in which one type of liquid flows among the processes performed by the blood purification apparatus 100B. calculate.
In addition, for change steps such as blood removal step and blood return step in which the type of flowing liquid gradually changes, using one or more correction parameters for one step, switching the correction parameter according to the change in the type of liquid Calculate the flow rate.

The switching of the plurality of correction parameters in the change step may be performed, for example, based on the elapsed time from the start of the change step. For example, in the blood removal step, correction parameters corresponding to the backfiltration dialysate are used for 10 seconds from the start of the blood removal step, and between 10 seconds to 20 seconds from the start of the blood removal step, the reverse filtration dialysate and blood are After 20 seconds from the start of the blood removal process, the flow rate is calculated using the correction parameter corresponding to blood, using the correction parameter corresponding to the mixed solution.
Alternatively, the correction parameter may be switched by measuring the change in color of the liquid using an infrared sensor or the like, detecting that the type of liquid flowing through the blood conduit 120 has changed.

  The control board 170 is incorporated inside the main body of the blood purification apparatus 100B, and the control board 170 is mounted with circuits that constitute the flow rate measuring circuit 20B and the control unit 160. Therefore, transmission and reception of signals between the determination unit 24 and the control unit 160 included in the flow rate measurement circuit 20B can be performed on the same substrate.

  According to the ultrasonic flowmeter 1B and the blood purification apparatus 100B of the second embodiment described above, the following effects can be obtained in addition to the effects (1) to (5) described above.

(6) The plurality of processes in the blood purification apparatus 100B include a changing process in which the type of flowing liquid gradually changes, and the flow rate calculating unit 26B determines that the process determined by the determining unit 24 is a changing process, The correction parameter is switched according to the change of the type of liquid in the changing step to calculate the corrected flow rate. As a result, even if the type of liquid changes in the changing process, the measurement error can be reduced and the measurement accuracy can be maintained.
In addition, in the change process such as the blood removal process and the blood return process, since the liquid flows at a low flow rate as compared with the priming process and the treatment process, the measurement error tends to be large in the measurement using the ultrasonic flowmeter. If the ultrasonic flowmeter 1B according to the second embodiment is used, measurement accuracy can be maintained even at low flow rates. Therefore, it is possible to accurately detect the occurrence of poor blood removal which tends to occur at the initial stage of the blood removal process, blood loss due to thrombus which easily occurs in the blood return process, and the like by the change of the measured flow rate.

  (7) The control board 170 provided in the blood purification apparatus 100B is incorporated in the main body of the blood purification apparatus 100B, and the circuit constituting the flow rate measurement circuit 20B and the control unit 160 is mounted. As a result, since transmission and reception of signals between the determination unit 24 and the control unit 160 included in the flow rate measurement circuit 20B can be performed on the same substrate, the delay of transmission of information between the determination unit 24 and the control unit 160 is reduced. The flow rate measurement accuracy can be improved. In addition, by collectively mounting the circuits on the same substrate, the manufacturing cost can be reduced.

(8) A pair of ultrasonic transducers 10A and 10B are disposed at a predetermined distance with respect to the flow direction of the fluid flowing through the blood conduit 120, and are attached to the same side in contact with the outside of the blood conduit 120. . Thus, compared to a configuration in which arranged opposite a pair of ultrasonic transducer obliquely, the distance L to the propagation of the ultrasonic signal is long, the propagation time of the ultrasonic signal is measured T _AB and T The measurement accuracy of _BA can be improved. Therefore, the measurement accuracy of the flow rate calculated based on the propagation times _TAB and _TBA can also be improved.

Although the preferred embodiments and examples of the ultrasonic flowmeter and blood purification apparatus of the present invention have been described above, the present invention is not limited to the above-described embodiments and examples, and can be appropriately modified. It is.
For example, in the above-mentioned embodiment, although explained using a dialysis device which performs hemodialysis (HD) as an example of a blood purification device, hemodialysis therapy such as hemofiltration (HF), hemofiltration dialysis (HDF), plasma exchange The present invention is also applicable to therapy and blood absorption therapy.

  Moreover, although the propagation time reciprocal difference method was shown as an example about the calculation method of the flow volume in an ultrasonic flow meter, well-known calculation methods, such as a propagation time difference method, a sing around method, a Doppler method, can be used.

  Further, with regard to the method of arranging the ultrasonic flow meter in the blood conduit, in the first embodiment, a pair of ultrasonic transducers are disposed diagonally oppositely, and in the second embodiment, a pair of ultrasonic transducers are arranged. Although the example which attached to the same side was shown, it does not restrict to this. For example, two pairs of ultrasonic transducers may be diagonally opposed and attached, or the ultrasonic signal may be transmitted and received using one ultrasonic transducer.

  Further, the arrangement position of the ultrasonic flowmeter in the blood conduit is not limited to the arrangement of the first embodiment and the second embodiment, but depends on the ease of attachment of the ultrasonic flowmeter to the tube, and the like. For example, the ultrasonic flow meter may be located on the blood introduction port 112a side of the connection portion between the drug line 123 and the artery side line 121 in the artery side line 121 shown in FIG. It may be between the detector 121b. Also, it may be between the drip chamber 122c and the vein-side air bubble detector 122b in the vein-side line 122, or may be between the vein-side clamp 122d and the vein-side connection portion 122a. That is, the ultrasonic flowmeter may be disposed at a position where the flow reduction on the artery side or the vein side can be detected.

  In the first embodiment, the control unit 160 of the blood purification apparatus 100A may intentionally generate the timing at which the blood pump 130 stops during the treatment process (for example, about 1 to 30 seconds per hour) Stop). This makes it possible to determine and correct the zero flow rate during blood purification, and to maintain high measurement accuracy even during a treatment process requiring several hours.

1A, 1B Ultrasonic Flowmeter 10A, 10B Ultrasonic Transducer 20A, 20B Flow Rate Measurement Circuit 21 Transmission Unit 22 Reception Unit 23 Transmission / Reception Switching Unit 24 Determination Unit 25 Storage Unit 26A, 26B Flow Rate Calculation Unit 100 Blood Purification Device 110 Blood Purification Means (Dializer)
120 blood conduit 130 blood pump 140 dialysate conduit 160 control section 170 control board

Claims (5)

An ultrasonic flowmeter for use in a blood purification apparatus, comprising: a blood conduit and a blood pump for flowing liquid through the blood conduit, wherein a plurality of steps of different types of liquid flowing in the blood conduit are performed,
An ultrasonic transducer mounted in contact with the outside of the blood conduit through which fluid flows and transmitting and receiving ultrasonic signals;
A flow rate measuring circuit for measuring the flow rate of the liquid based on an ultrasonic signal transmitted and received by the ultrasonic transducer.
The flow rate measuring circuit
A transmitter configured to transmit an ultrasonic signal to the ultrasonic transducer;
A receiver for receiving an ultrasonic signal from the ultrasonic transducer;
A storage unit which stores in advance a plurality of correction parameters according to the type of liquid;
A determination unit that determines which process among the plurality of processes the blood purification apparatus is in;
The correction parameter stored in the storage unit according to the type of liquid flowing in the step determined by the ultrasonic wave signal transmitted by the transmission unit, the ultrasonic wave signal received by the reception unit, and the determination unit And a flow rate calculating unit that calculates the corrected flow rate based on
Ultrasonic flowmeter comprising. The blood purification apparatus includes a control unit that switches and controls the plurality of steps.
The ultrasonic flowmeter according to claim 1, wherein the determination unit determines the process by receiving, from the control unit, process information performed by the blood purification apparatus. The plurality of steps include a changing step in which the type of flowing liquid gradually changes;
When the process determined by the determination unit is the change process, the flow rate calculation unit calculates the corrected flow rate by switching the correction parameter according to a change in the type of liquid in the change process. Or the ultrasonic flowmeter as described in 2. The ultrasonic flowmeter comprises at least one pair of ultrasonic transducers arranged at a predetermined distance in the flow direction of the liquid flowing through the blood conduit,
The ultrasonic flowmeter according to any one of claims 1 to 3, wherein the ultrasonic transducer transmits and receives ultrasonic signals obliquely to the flow direction of the liquid.   A blood purification apparatus comprising: the ultrasonic flowmeter according to any one of claims 1 to 4; a blood conduit; and a blood pump for flowing liquid through the blood conduit.

Images