JP2018201823A - Ultrasound measurement apparatus and extracorporeal circulation apparatus - Google Patents

Abstract

To provide an ultrasound measurement apparatus for use with an extracorporeal circulation apparatus to allow measurement of blood flow rate and density.SOLUTION: An ultrasound measurement apparatus 1A is used with an extracorporeal circulation apparatus 100A, and includes ultrasound transceivers 10A, 10B attached to a blood circuit 110, and a measurement circuit 20A for measuring blood flow rate and density. The measurement circuit 20A comprises: a transmitter 21; a receiver 22; a flow rate calculation unit 24A for calculating a blood flow rate based on a transmission signal transmitted by the transmitter 21 and a reception signal received by the receiver 22; and a density calculation unit 25 for calculating a blood density based on an attenuation degree of the reception signal amplitude with respect to the transmission signal amplitude.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ultrasonic measurement device used in an extracorporeal circulation system that circulates blood of a patient outside the body.

Blood purification devices used for treatments such as hemodialysis, plasma exchange, and adsorption therapy, and extracorporeal circulation devices such as an artificial cardiopulmonary device are generally blood treatments such as blood conduits, blood purifiers, and blood concentrators for flowing blood. Means, a blood pump for delivering blood, and circulating the patient's blood outside the body.
It is necessary to monitor the blood flow rate through the blood conduit in order to detect poor blood removal from the patient, clogging of the blood conduit due to thrombus, etc., and an ultrasonic flow meter is used to monitor this blood flow rate ( (See Patent Documents 1 and 2).

  In blood purification therapy, water is removed from blood circulating outside the body by a blood purification means. Therefore, the blood concentration is monitored by a concentration meter such as a hematocrit sensor so that the water removal amount is appropriate, and the water removal speed is controlled (see Patent Document 3).

JP 2008-023269 A JP 2003-169893 A JP 2004-097882 A

  As described above, in the extracorporeal circulation, it is necessary to use a flow meter for blood flow measurement and a concentration meter for blood concentration measurement, respectively, which increases the production cost of the apparatus and makes the assembly work of the blood circuit complicated. There was a problem.

  Therefore, an object of the present invention is to provide an ultrasonic measurement device that is used in an extracorporeal circulation device and can measure the flow rate and concentration of blood.

  In the blood purification therapy, an extracorporeal circulation apparatus comprising a blood circuit for flowing blood and blood purification means connected to the blood circuit and capable of removing water in the blood, and circulating the blood extracorporeally. An ultrasonic measurement device to be used, which is attached to the blood circuit, converts an electrical signal and an ultrasonic signal, and transmits and receives an ultrasonic signal, and is transmitted and received by the ultrasonic transmitter / receiver. A measurement circuit that measures the flow rate and concentration of blood based on the ultrasonic signal, and the measurement circuit includes: a transmission unit that transmits an electrical signal to the ultrasonic transducer; and the ultrasonic transducer A receiving unit that receives an electrical signal, a flow rate calculating unit that calculates a blood flow rate based on the transmission signal transmitted by the transmitting unit and the received signal received by the receiving unit, and the received signal with respect to the amplitude of the transmission signal Amplitude of A density calculation section for calculating a blood concentration based on the attenuation degree, an ultrasonic measuring device comprising a.

  In the blood purification therapy, the blood circuit includes an arterial line for flowing blood introduced into the blood purification means, and a vein side line for flowing blood derived from the blood purification means. Preferably, the ultrasonic transducer is attached to the arterial line.

  In addition, the ultrasonic measurement device may include at least a pair of the ultrasonic waves arranged at a predetermined distance in the flow direction of the blood flowing through the blood circuit, with the blood circuit interposed therebetween, or opposed to the blood flow line. It is preferable to provide a transducer, and the ultrasonic transducer transmits and receives an ultrasonic signal obliquely with respect to the blood flow direction or upstream and downstream with respect to the flow direction.

  Further, it is preferable that the flow rate calculation unit measures a propagation time in blood of ultrasonic signals transmitted and received between the ultrasonic transducers, and calculates a blood flow rate by a reciprocal propagation time difference method.

  The present invention further includes an extracorporeal device for circulating the blood extracorporeally, comprising the ultrasonic measuring device, a blood circuit for flowing blood, and blood purification means connected to the blood circuit and capable of removing water in the blood. It relates to a circulation device.

  Moreover, it is preferable to further include a control unit that controls the water removal rate in the blood purification means based on the calculated concentration calculated by the concentration calculating unit.

  In addition, it is preferable that a notification unit for notifying the abnormality is further provided when the calculated flow rate calculated by the flow rate calculation unit is abnormal.

  According to the ultrasonic measurement device of the present invention, the blood flow rate can be measured based on the ultrasonic signal transmitted and received by the ultrasonic transducer, and based on the attenuation degree of the ultrasonic signal propagated in the blood. Blood concentration can be measured.

It is explanatory drawing which shows the structure of 1st Embodiment of this invention. It is a figure which shows schematic structure of an extracorporeal circulation apparatus (dialysis apparatus). It is a figure which shows the dialysis process implemented with an extracorporeal circulation apparatus (dialysis apparatus). It is a figure which shows the rapid rehydration process implemented with an extracorporeal circulation apparatus (dialysis apparatus). It is explanatory drawing which shows the structure of 2nd Embodiment of this invention. It is a figure which shows the correspondence of the blood concentration in Example 1, and the attenuation degree. It is a figure which shows the correspondence of the blood concentration in Example 1, and the attenuation degree. It is a figure which shows the installation state of the ultrasonic measuring device in an Example.

Hereinafter, preferred embodiments of the ultrasonic measurement device and the extracorporeal circulation device of the present invention will be described with reference to the drawings. In the present invention, a blood purification apparatus that performs hemodialysis will be described as an example of an extracorporeal circulation apparatus.
In hemodialysis, blood is purified while circulating blood of a renal failure patient or a drug addicted patient at a predetermined flow rate, and excess water in the blood is removed. As the water in the blood is gradually removed, the blood concentration gradually increases. The ultrasonic measurement apparatus according to the present invention is capable of measuring the blood concentration and measuring the blood flow rate.

<First Embodiment>
FIG. 1 is an explanatory diagram showing the configuration of a blood purification device 100A as an extracorporeal circulation device according to the first embodiment of the present invention and an ultrasonic measurement device 1A used in the device, and FIG. 2 is a diagram of the blood purification device 100A. It is a figure which shows schematic structure of these.

  As shown in FIGS. 1 and 2, the blood purification apparatus 100A includes a blood circuit 110 for flowing blood, a dialyzer 120 as blood purification means, a dialysate circuit 130, a control unit 140A, and a blood circuit 110. 1 A of ultrasonic measuring devices arrange | positioned.

  The blood circuit 110 includes an artery side line 111, a vein side line 112, a drug line 113, and a drain line 114. The arterial side line 111, the venous side line 112, the drug line 113, and the discharge line 114 are all composed mainly of a flexible soft tube through which fluid can flow.

One end side of the artery side line 111 is connected to a blood introduction port 122a of a dialyzer 120 described later. In the artery side line 111, a patient side artery connecting part 111a, an artery side bubble detector 111b, a blood pump 111c, and an ultrasonic measuring device 1A described later are arranged.
The patient-side arterial connection portion 111 a is disposed on the other end side of the artery-side line 111. A needle that is punctured into a patient's blood vessel is connected to the patient-side artery connecting portion 111a.
The arterial bubble detector 111b detects the presence or absence of bubbles in the tube.
The blood pump 111c is disposed on the downstream side of the artery side bubble detector 111b in the artery side line 111. The blood pump 111c sends out liquid such as blood and priming liquid inside the artery side line 111 by squeezing the tube constituting the artery side line 111 with a roller.
As shown in FIG. 2, the ultrasonic measurement apparatus 1 </ b> A is disposed on the downstream side of the blood pump 111 c in the artery side line 111. Although the ultrasonic measurement apparatus 1A may be attached at any position in the blood circuit 110, in the present embodiment, the ultrasonic measurement apparatus 1A is attached downstream of the blood pump 111c of the artery side line 111. By attaching to this position, it is difficult to be affected by water removal or water injection by the dialyzer 120, and it is not necessary to calculate water removal or water injection, and measurement errors can be reduced.

The blood circuit 110 (arterial line 111) has a blood flow direction substantially vertical so that bubbles in the blood circuit 110 that affect the flow rate measurement do not stay at the site where the ultrasonic measurement apparatus 1A is attached. Is held to be. Further, it is desirable to arrange the upstream side in the blood flow direction of the dialysis step at the lower part and the downstream side at the upper part so that the bubbles can rise quickly.
A specific configuration of the ultrasonic measurement apparatus 1A will be described later.

One end side of the venous line 112 is connected to a blood outlet 122b of the dialyzer 120 described later. In the venous side line 112, a patient side venous connection part 112a, a venous side bubble detector 112b, a drip chamber 112c, and a venous side clamp 112d are arranged.
The patient side vein connecting portion 112a is disposed on the other end side of the vein side line. A needle that is punctured into a patient's blood vessel is connected to the patient-side vein connection portion 112a.
The venous bubble detector 112b detects the presence or absence of bubbles in the tube.
The venous bubble detector 112b is disposed downstream of the drip chamber 112c. The drip chamber 112c stores a certain amount of blood in order to remove bubbles mixed in the venous line 112, coagulated blood, and the like, and to measure venous pressure.
The vein-side clamp 112d is disposed downstream of the vein-side bubble detector 112b. The vein-side clamp 112d is controlled according to the bubble detection result by the vein-side bubble detector 112b, and opens and closes the flow path of the vein-side line 112.

  The drug line 113 supplies a drug required during hemodialysis to the artery side line 111. One end of the drug line 113 is connected to a chemical pump 113 a that sends out the drug, and the other end is connected to the arterial line 122. In the present embodiment, the other end side of the drug line 113 is connected to the downstream side of the ultrasonic measurement device 1 </ b> A in the artery side line 122.

  The discharge line 114 is connected to the drip chamber 112c. A discharge line clamp 114 a is disposed on the discharge line 114. The discharge line 114 is a line for discharging the priming liquid in a priming process described later.

  The dialyzer 120 includes, for example, a container body 121 formed in a cylindrical shape, and a dialysis membrane (not shown) accommodated in the container body 121. The inside of the container body 121 is blood by a dialysis membrane. It is divided into a side channel and a dialysate side channel (both not shown). In the container body 121, a blood introduction port 122a and a blood outlet port 122b that communicate with the blood circuit 110, and a dialysate inlet port 123a and a dialysate outlet port 123b that communicate with the dialysate circuit 130 are formed.

  According to the blood circuit 110 and the dialyzer 120 described above, blood taken out from the artery of the subject (dialysis patient) is circulated through the artery side line 111 by the blood pump 111c and introduced into the blood side channel of the dialyzer 120. . The blood introduced into the dialyzer 120 is purified by dialysate flowing through a dialysate circuit 130 described later via a dialysis membrane. The blood purified in the dialyzer 120 flows through the vein side line 112 and is returned to the subject's vein.

  In the present embodiment, the dialysate circuit 130 is configured by a so-called sealed capacity control type dialysate circuit 130. The dialysate circuit 130 includes a dialysate supply line 131a, a dialysate discharge line 131b, a dialysate introduction line 132a, a dialysate lead-out line 132b, and a dialysate feed section 133.

The dialysate feeding section 133 includes a dialysate chamber 1331, a bypass line 1332, and a water removal / back filtration pump 1333.
The dialysate chamber 1331 is composed of a hard container that can store a predetermined volume (for example, 300 ml to 500 ml) of dialysate, and the inside of the container is partitioned by a soft diaphragm (diaphragm), and a liquid feeding container 1331a and It is partitioned into a discharge container 1331b.
The bypass line 1332 connects the dialysate outlet line 132b and the dialysate discharge line 131b.

  The dewatering / back filtration pump 1333 is disposed in the bypass line 1332. The dewatering / back filtration pump 1333 is in a direction in which the dialysate inside the bypass line 1332 is circulated to the dialysate discharge line 131b (water removal direction) and a direction in which the dialysate is circulated to the dialysate outlet line 132b (reverse filtration direction). It is composed of a pump that can be fed.

  The dialysate supply line 131a has a proximal end connected to a dialysate supply apparatus (not shown) and a distal end connected to the dialysate chamber 1331. The dialysate supply line 131 a supplies the dialysate to the liquid supply container 1331 a of the dialysate chamber 1331.

  The dialysate introduction line 132 a connects the dialysate chamber 1331 and the dialysate introduction port 123 a of the dialyzer 120, and allows the dialysate contained in the liquid feed accommodating portion 1331 a of the dialysate chamber 1331 to flow through the dialysate-side flow path of the dialyzer 120. To introduce.

  The dialysate lead-out line 132 b connects the dialysate lead-out port 123 b of the dialyzer 120 and the dialysate chamber 1331, and guides the dialysate discharged from the dialyzer 120 to the discharge housing portion 1331 b of the dialysate chamber 1331.

  The proximal end side of the dialysate discharge line 131b is connected to the dialysate chamber 1331, and discharges the dialysate stored in the discharge storage portion 1331b.

According to the dialysate circuit 130 described above, the amount of dialysate derived from the dialysate chamber 1331 (liquid supply accommodation) is determined by partitioning the inside of the hard container constituting the dialysate chamber 1331 with the soft diaphragm (diaphragm). The amount of dialysate supplied to the portion 1331a) and the amount of discharge collected in the dialysate chamber 1331 (discharge storage portion 1331b) can be made equal.
Thereby, in a state where the water removal / back-filtration pump 1333 is stopped, the flow rate of the dialysate introduced into the dialyzer 120 and the amount of dialysate (discharge) derived from the dialyzer 120 can be made equal.

  In addition, when the dewatering / back filtration pump 1333 is driven to send liquid in the reverse filtration direction, a part of the discharge discharged from the dialysate chamber 1331 passes through the bypass line 1332 and the dialysate outlet line 132b. Then, it is collected again in the dialysate chamber 1331. Therefore, the amount of dialysate derived from the dialyzer 120 is the amount of dialysate flowing through the bypass line 1332 from the amount recovered in the dialysate chamber 1331 (that is, the amount of dialysate flowing through the dialysate introduction line 132a). The amount is reduced. As a result, the amount of dialysate derived from the dialyzer 120 passes through the dialysate introduction line 132a by the amount of dialysate (discharge) recovered through the bypass line 1332 and returned to the dialysate chamber 1331 again. Less than the flow rate. That is, when the dewatering / reverse filtration pump 1333 is driven so as to send liquid in the reverse filtration direction, a predetermined amount of dialysate is injected (reverse filtration) into the blood circuit 110 in the dialyzer 120 (see FIG. 4). ).

  On the other hand, when the water removal / reverse filtration pump 1333 is driven so as to send the liquid in the water removal direction, the amount of the dialysate flowing through the dialysate lead-out line 132b is the dialysate recovered in the dialysate chamber 1331. (Ie, the amount of dialysate flowing through the dialysate introduction line 132a) plus the amount of dialysate flowing through the bypass line 1332. Thereby, the amount of dialysate flowing through the dialysate outlet line 132b flows through the dialysate introduction line 132a by the amount of dialysate (discharge) discharged through the bypass line 1332 to the dialysate discharge line 131b. More than the amount of dialysate. That is, when the water removal / reverse filtration pump 1333 is driven so as to send liquid in the water removal direction, a predetermined amount of water is removed from the blood in the dialyzer 120 (see FIG. 3).

140 A of control parts are comprised by information processing apparatus (computer), and control operation | movement of 100 A of blood purification apparatuses by running a control program. Further, the control unit 140A is connected to the ultrasonic measurement apparatus 1A, and information on the measured blood flow rate and blood concentration is transmitted to the control unit 140A.
Specifically, the control unit 140A controls operations of various pumps and clamps disposed in the blood circuit 110 and the dialysate circuit 130 to perform various processes performed by the blood purification apparatus 100A, such as a priming process, A blood removal process, a dialysis process, a rapid fluid replacement process, a blood return process, etc. are performed.

Various processes will be briefly described.
In the priming step, the blood circuit 110 and the dialyzer 120 are washed and cleaned with a priming solution such as a reverse filtration dialysis solution or physiological saline. In the blood removal step before entering the dialysis step, the blood of the patient is sucked to fill the artery side line 111 and the vein side line 112 with blood. After the blood removal step, a dialysis step is performed to purify the blood shown in FIG. 3 and remove water.
A rapid fluid replacement step shown in FIG. 4 is performed during the dialysis step as necessary. After completion of the dialysis process, a blood return process for returning blood to the patient is performed.

  Below, among the various processes performed by the blood purification apparatus 100A, the dialysis process and the rapid replacement liquid process related to the blood concentration change will be described in detail.

The dialysis process will be described with reference to FIG.
In the dialysis process, the blood of the patient introduced from the patient-side arterial connection 111a is purified by the dialyzer 120 through the arterial-side line 111 and returned to the patient through the venous-side line 112 from the patient-side venous connection 112a. .

  In the dialysis step, as shown in FIG. 3, the patient-side arterial connection portion 111a and the patient-side vein connection portion 112a are each connected to a needle that is punctured into the patient's blood vessel, and the drain line clamp 114a is closed. State, the vein side clamp 112d is in an open state.

For example, the dialysate is supplied to the dialyzer 120 from the dialysate chamber 1331 at a feed rate of 500 ml / min, and the water removal / back-filtration pump 1333 is operated so as to feed in the water removal direction. For example, 10 ml / min is removed in the dialyzer 120 by setting the feed rate of the water removal / reverse filtration pump 1333 to 10 ml / min (the dialysate from the dialysate circuit 130 at a flow rate of 510 ml / min). Is discharged).
The blood pump 111c delivers blood from the patient side arterial connection 111a side to the dialyzer 120 side at, for example, about 200 ml / min.
Blood flows into the dialyzer 120 from the blood inlet 122a at a flow rate of 200 ml / min, dehydrated at a flow rate of 10 ml / min, and purified blood is discharged from the blood outlet 122b at a flow rate of 190 ml / min. Is done. The dialysate is led out from the dialysate outlet 123b.
In this way, in the dialysis step, water is gradually removed from the blood, and the blood concentration gradually increases accordingly.

Next, the rapid replenishment process will be described with reference to FIG.
The rapid replenishment step is performed when a decrease in blood pressure due to water removal is observed during the dialysis step, and is a step of replenishing the blood circuit 110 with a reverse filtration dialysate.

  In the rapid fluid replacement process, as shown in FIG. 4, the patient-side arterial connection part 111a and the patient-side vein connection part 112a are connected to needles that are punctured into the patient's blood vessels, as in the dialysis process. The line clamp 114a is in a closed state and the vein side clamp 112d is in an open state.

For example, dialysate is supplied from the dialysate chamber 1331 to the dialyzer 120 at a feed rate of 500 ml / min, and the dewatering / back filtration pump 1333 is operated so as to feed in the reverse filtration direction. By setting the feed rate of the water removal / reverse filtration pump 1333 to 100 ml / min as an example, water is injected at 100 ml / min in the dialyzer 120 (the dialysate is supplied from the dialysate circuit 130 at a flow rate of 400 ml / min). Discharged).
For example, the blood pump 111c reduces the flow rate from 200 ml / min during the dialysis process to about 50 ml / min, and sends blood from the patient-side arterial connection 111a side to the dialyzer 120 side.
Blood flows into the dialyzer 120 from the blood inlet 122a at a flow rate of 50 ml / min, and the reverse filtration dialysate is injected at a flow rate of 100 ml / min, and the blood diluted from the blood outlet port 122b is 150 ml / min. It is derived by the flow rate. In this way, water is replenished in the blood in the rapid replacement process.

Next, the ultrasonic measurement apparatus 1A will be described in detail with reference to FIG.
The ultrasonic measurement apparatus 1A includes a pair of ultrasonic transducers 10A and 10B and a measurement circuit 20A that measures the flow rate and concentration of blood, and is attached to a blood circuit 110 included in the blood purification apparatus 100A.

The ultrasonic transducers 10 </ b> A and 10 </ b> B each include a piezoelectric element 11 and a piezoelectric element cover 12. The ultrasonic transducers 10A and 10B are arranged at a predetermined distance in the flow direction of blood such as blood flowing through the blood circuit 110 or a reverse filtration dialysate. For example, the ultrasonic transducers 10 </ b> A and 10 </ b> B are attached so as to face each other with the blood circuit 110 interposed therebetween so as to contact the outside of the blood circuit 110 (tube), and can transmit and receive ultrasonic signals.
Electrodes (not shown) are respectively attached to both surfaces of the piezoelectric element 11, and the piezoelectric element 11 converts the input electric signal into mechanical vibration, and converts the transmitted mechanical vibration into an electric signal. Can be output. The piezoelectric element 11 is embedded in a piezoelectric element cover 12 formed of hard polyvinyl chloride, polycarbonate, or the like. 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 this embodiment, lead zirconate titanate is used as the material of the piezoelectric element.

The ultrasonic transducers 10A and 10B may be mounted on the same side of the blood circuit 110 at a predetermined distance so as to receive an ultrasonic signal reflected from the inner surface of the tube constituting the blood circuit 110. . However, since the concentration calculation unit 25, which will be described later, calculates the concentration by measuring the attenuation degree of the ultrasonic signal, it is not a reflected wave that needs to consider attenuation due to reflection on the inner surface of the tube, but mainly in blood. It is desirable to arrange the ultrasonic transducers 10A and 10B to face each other so that a transmitted wave reflecting attenuation in the blood cell can be received.
In addition, in order to measure the ultrasonic signal in a moderately attenuated state, the distance between the ultrasonic transducers 10A and 10B in the direction of blood flow through the blood circuit 110 is the outer diameter of the tube constituting the blood circuit 110. It is desirable to make it about 1 to 2 times. A distance shorter than 1 time is not desirable because the time difference is small in the inverse propagation time difference method. On the other hand, if the distance is longer than twice, the measurement error of the attenuated ultrasonic signal increases due to the excessive attenuation, which is not desirable.

The measurement circuit 20A includes a transmission unit 21, a reception unit 22, a transmission / reception switching unit 23, a flow rate calculation unit 24A, a concentration calculation unit 25, and a storage unit 26, and includes ultrasonic transducers 10A and 10B. The blood flow rate and concentration are measured based on the transmitted and received ultrasonic signals.
There are various methods for measuring flow rate using ultrasonic waves, such as a propagation speed difference method (propagation time difference method, propagation time reciprocal difference method), a Doppler method, etc. An example using the propagation time reciprocal difference method will be described.

The transmitting unit 21 is connected to the piezoelectric element 11 of the ultrasonic transducer 10A or 10B via the transmission / reception switching unit 23, and transmits an electrical signal to the ultrasonic transducers 10A and 10B.
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 electrical signals from the ultrasonic transducers 10A, 10B, and amplifies the received electrical signals. .
The transmission / reception switching unit 23 switches one of the ultrasonic transducers 10 </ b> A and 10 </ b> B to the transmission unit 21 and the other to the reception unit 22. As a result, the transmission / reception switching unit 23 transmits the ultrasonic signal from the ultrasonic transducer 10A and receives the ultrasonic signal from the ultrasonic transducer 10B and the ultrasonic signal from the ultrasonic transducer 10B. Thus, it is possible to measure the propagation time when received by the ultrasonic transducer 10A.

  The flow rate calculation unit 24 </ b> A calculates the flow rate based on the transmission signal that is the electrical signal transmitted by the transmission unit 21 and the reception signal that is the electrical signal received by the reception unit 22. The flow rate calculation unit 24A measures the timing of transmitting the transmission signal in the transmission unit 21 and the timing of receiving the reception signal in the reception unit 22, thereby propagating the ultrasonic signal propagating between the ultrasonic transducers 10A and 10B. Calculate time.

  A method for calculating the flow rate Q using the propagation time reciprocal difference method will be described in detail below. The ultrasonic transducers 10A and 10B transmit and receive ultrasonic signals obliquely with respect to the liquid flow direction. Specifically, it is arranged facing the outside of the blood circuit 110 (arterial line) so that the angle formed by the direction in which the ultrasonic signal is transmitted and received and the flow direction of the liquid is a predetermined angle φ, and alternately A sound signal is transmitted and received, and the time required for propagation of the ultrasonic signal is measured.

The time for the ultrasonic signal to propagate from the ultrasonic transducers 10A to 10B is T _AB , the time for the ultrasonic signal to propagate from the ultrasonic transducers 10B to 10A is T _BA , and the distance for the ultrasonic signal to propagate is L, Let C be the speed of sound and V be the flow velocity of the liquid in the blood circuit 110.
When the actual flow rate is zero, that is, the flow velocity V is zero when the blood circuit 110 is filled with liquid, T _AB and T _BA are equal,
T _AB = T _BA = L / C (a)
It becomes.

As shown in FIG. 1, when the liquid flows at a flow velocity V from the ultrasonic transducer 10A side toward the ultrasonic transducer 10B side,
T _AB = L / (C + V cos φ) (b)
And
T _BA = L / (C−V cos φ) (c)
It becomes. From the relationship between these equations (b) and (c), taking the difference of the reciprocals of the propagation times T _AB and T _BA ,
1 / T _AB -1 / T _BA = (2 V cos φ) / L (d)
It becomes. When the flow velocity V is obtained from the equation (d),
V = L / (2cosφ) × (1 / T _AB −1 / T _BA ) (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 velocity V does not depend on the speed of sound C depending on the type and temperature of fluids such as blood and dialysate having different concentrations. The flow rate V can be calculated without multiplying the flow rate V, and the flow rate Q can be calculated by multiplying the flow rate V by the cross-sectional area A of the tube constituting the blood circuit 110.
Q = V × A (f)

The concentration calculation unit 25 calculates the blood concentration based on the degree of attenuation of the amplitude of the reception signal received by the reception unit 22 with respect to the amplitude of the transmission signal transmitted by the transmission unit 21. Here, the blood concentration can be generally evaluated by a hematocrit value. The hematocrit value represents the proportion of red blood cells present in the blood. Blood cells make up about 45% of the total blood volume and include red blood cells, white blood cells and platelets, most of which are red blood cells. Therefore, the hematocrit value indicates the abundance ratio of red blood cells and is used as an indicator of blood concentration.
When propagating through the blood, the ultrasonic signal is attenuated by being scattered by blood cells existing in the blood. Therefore, the degree of attenuation of the amplitude of the reception signal with respect to the amplitude of the transmission signal changes according to the blood concentration. Therefore, a correspondence relationship between the blood concentration and the degree of attenuation is obtained in advance for a sample with a known blood concentration, and the correspondence relationship is stored in the storage unit 26.
The concentration calculation unit 25 calculates the blood concentration of the blood whose concentration is unknown based on the attenuation level of the received signal and the correspondence between the blood concentration and the attenuation level stored in the storage unit 26.

  Based on the calculated concentration calculated by the concentration calculation unit 25 during the dialysis process, the blood purification device 100A controls the dialysate liquid feeding unit 133 by the control unit 140A to adjust the water removal rate in the dialyzer 120. It is possible to treat the patient while suppressing a decrease in blood pressure of the patient.

  The ultrasonic measurement apparatus 1A and the blood purification apparatus 100A according to the first embodiment described above have the following effects.

  (1) The ultrasonic measurement apparatus 1A includes ultrasonic transducers 10A and 10B and a measurement circuit 20A, and the measurement circuit 20A transmits an electrical signal to the ultrasonic transducers 10A and 10B. And a receiving unit 22 that receives electrical signals from the ultrasonic transducers 10A and 10B, and a flow rate that calculates the blood flow rate based on the transmission signal transmitted by the transmitting unit 21 and the received signal received by the receiving unit 22 The calculation unit 24A and a concentration calculation unit that calculates a blood concentration based on the degree of attenuation of the amplitude of the reception signal with respect to the amplitude of the transmission signal are provided. Thus, the flow rate and concentration of blood can be measured with one ultrasonic measurement device 1A without using two measurement devices, a flow meter and a concentration meter. Therefore, the blood purification apparatus 100A capable of measuring the blood flow rate and concentration with a simple configuration can be realized.

  (2) Arterial line 111 for flowing blood introduced into blood purification means (dialyzer) 120 and venous side line 112 for flowing blood derived from blood purification means (dialyzer) 120 through blood circuit 110 The ultrasonic transducers 10A and 10B are attached to the artery side line 111. As a result, the blood flow rate at the measurement site is not easily affected by water removal or water injection by the blood purification means (dialyzer) 120, and it is not necessary to calculate water removal or water injection, thereby reducing measurement errors.

  (3) The ultrasonic measurement apparatus 1A includes a pair of ultrasonic transducers 10A and 10B that are arranged to face each other with the blood circuit 110 interposed therebetween with a predetermined distance in the flow direction of the blood flowing through the blood circuit 110. For example, the ultrasonic transducers 10A and 10B transmit and receive ultrasonic signals obliquely with respect to the blood flow direction. Thereby, the flow rate of the liquid can be measured with a simple configuration having one measuring line, and the manufacturing cost can be reduced as compared with the configuration having a plurality of measuring lines. In addition, the ultrasonic signal transmitted from the ultrasonic transducer 10A (or 10B) is not a reflected wave reflected from the inner surface of the tube constituting the blood circuit 110, but is transmitted as an ultrasonic transducer 10B (or 10A). ), There is no reflection attenuation on the inner surface of the tube, so that the measurement accuracy of the received signal attenuation degree can be increased.

  (4) The distance between the ultrasonic transducers 10 </ b> A and 10 </ b> B in the direction of blood flow through the blood circuit 110 is set to 1 to 2 times the outer diameter of the tube constituting the blood circuit 110. Thereby, the flow volume and density | concentration of blood can be measured suitably.

  (5) The flow rate calculation unit 24A measures the propagation time in the blood of the ultrasonic signals transmitted and received between the pair of ultrasonic transducers 10A and 10B, respectively, and calculates the blood flow rate by the inverse propagation time difference method. It was supposed to be. As a result, the flow rate can be calculated without being affected by changes in the blood concentration and the temperature-dependent sound velocity C.

  (6) The blood circuit 110 (arterial line 111) is held so that the flow direction of the liquid is substantially vertical at the site where the ultrasonic measurement apparatus 1A is attached. Thereby, since the bubbles in the blood circuit 110 can be prevented from staying, the influence of the bubbles on the measurement of the blood flow rate and concentration can be reduced.

  (7) The blood circuit 110 (arterial line 111) is arranged so that the upstream side in the liquid flow direction is the lower side and the downstream side is the upper side in the site where the ultrasonic measurement device 1A is attached. Thereby, since the bubbles in the blood circuit 110 at the flow rate measurement site can rise quickly, the influence of the bubbles on the measurement of the blood flow rate and concentration can be reduced.

  (8) Based on the calculated concentration calculated by the concentration calculation unit 25, the control unit 140A of the blood purification device 100A adjusts the water removal rate in the dialyzer 120 as the blood purification unit. Thereby, it is possible to treat the patient while suppressing a decrease in blood pressure of the patient in the dialysis process.

Second Embodiment
Next, a second embodiment will be described with reference to FIG.
FIG. 5 is an explanatory diagram showing the configuration of the blood purification device 100B according to the second embodiment of the present invention and the ultrasonic measurement device 1B used in the device. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. The second embodiment is different from the first embodiment in that the blood purification device includes a notification unit and the measurement circuit of the ultrasonic measurement device is incorporated in the control board of the blood purification device.

As shown in FIG. 5, blood purification apparatus 100B includes blood circuit 110, dialyzer 120 as blood purification means, dialysate circuit 130, control unit 140B, notification means 150, control board 160, and ultrasonic wave. Measuring device 1B.
Since each process implemented in the blood purification apparatus 100B is the same as that of the case of 1st Embodiment, description is abbreviate | omitted.

  The ultrasonic measurement apparatus 1B includes a pair of ultrasonic transducers 10A and 10B attached to the blood circuit 110, and a measurement circuit 20B that measures the flow rate and concentration of blood.

  The ultrasonic transducers 10 </ b> A and 10 </ b> B each include a piezoelectric element 11 and a piezoelectric element cover 12. The ultrasonic transducers 10 </ b> A and 10 </ b> B are arranged at a predetermined distance in the flow direction of the liquid flowing through the blood circuit 110.

  The measurement circuit 20B includes a transmission unit 21, a reception unit 22, a transmission / reception switching unit 23, a flow rate calculation unit 24B, a concentration calculation unit 25, and a storage unit 26, and includes ultrasonic transducers 10A and 10B. The blood flow rate and concentration are measured based on the transmitted and received ultrasonic signals.

  The flow rate calculation unit 24 </ b> B calculates the flow rate based on the transmission signal that is the electrical signal transmitted by the transmission unit 21 and the reception signal that is the electrical signal received by the reception unit 22. The flow rate calculation unit 24B measures the timing at which the transmission unit 21 transmits the transmission signal and the reception unit 22 receives the reception signal, thereby propagating the ultrasonic signal propagating between the ultrasonic transducers 10A and 10B. Calculate time.

  In the present embodiment, the flow rate Q is calculated as follows using a propagation time difference method different from the propagation time reciprocal difference method used in the first embodiment. The ultrasonic transducers 10A and 10B transmit and receive ultrasonic signals obliquely with respect to the liquid flow direction. Specifically, the ultrasonic signal is alternately sent and received so that the angle formed by the direction in which the ultrasonic signal is transmitted and received and the flow direction of the liquid is a predetermined angle φ, facing the outside of the blood circuit 110. The time required for propagation of the ultrasonic signal is measured.

The time for the ultrasonic signal to propagate from the ultrasonic transducers 10A to 10B is T _AB , the time for the ultrasonic signal to propagate from the ultrasonic transducers 10B to 10A is T _BA , and the distance for the ultrasonic signal to propagate is L, Let C be the speed of sound and V be the flow velocity of the liquid in the blood circuit 110.
When the actual flow rate is zero, that is, the flow velocity V is zero when the blood circuit 110 is filled with liquid, T _AB and T _BA are equal,
T _AB = T _BA = L / C (a)
It becomes.

When the liquid flows from the ultrasonic transducer 10A side toward the ultrasonic transducer 10B side at a flow velocity V as shown in FIG.
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 of these equations (b) and (c), the square of the flow velocity V is sufficiently smaller than the square of the sound velocity C, so it is approximated,
T _AB −T _BA = (2LV cos φ) / (C ² −V ² cos ² φ)
^{≒ (2LVcosφ) / C 2 ···} (d) '
It becomes. (D) '
V = C ² / (2L 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 tube constituting the blood circuit 110.
Q = V × A (f)

  When the flow rate is calculated using the propagation time difference method, the sound speed C slightly changes according to the change in blood concentration. Therefore, when the flow rate is calculated using (e) ', the measurement accuracy of the flow rate can be further improved by using the sound velocity C corrected in accordance with the calculated concentration calculated by the concentration calculation unit 25.

The control unit 140B is configured by an information processing device (computer), and controls the operations of the blood purification device 100B and the ultrasonic measurement device 1B by executing a control program.
Specifically, the control unit 140B controls operations of various pumps and clamps disposed in the blood circuit 110 and the dialysate circuit 130 to perform various processes performed by the blood purification apparatus 100B, such as a priming process, A blood removal process, a dialysis process, a rapid fluid replacement process, a blood return process, etc. are performed.
The control unit 140B determines that there is an abnormality such as a poor blood removal state when the difference between the calculated flow rate calculated by the flow rate calculation unit 24B and the set flow rate of the blood pump 111c is large. When it is determined that there is an abnormality, the control unit 140B performs control so that the set flow rate of the blood pump 111c is reduced or the blood pump 111c is stopped, and the notification unit 150 described later is operated. Further, the control unit 140B controls the dialysate liquid feeding unit 133 according to the calculated concentration calculated by the concentration calculating unit 25 during the dialysis step, thereby controlling the water removal rate in the dialyzer 120.

  The notification unit 150 operates when the controller 140B determines that the calculated flow rate is abnormal, and notifies the medical staff of the abnormality.

  The control board 160 is incorporated in the main body of the blood purification apparatus 100B, and the circuit constituting the measurement circuit 20B and the control unit 140A is mounted on the control board 160. Therefore, transmission and reception of signals with the flow rate calculation unit 24B and the concentration calculation unit 25 included in the measurement circuit 20B can be performed on the same substrate.

  According to the ultrasonic measurement apparatus 1B and the blood purification apparatus 100B of the second embodiment described above, in addition to the effects (1) to (4) and (6) to (8) described above, the following effects can be obtained. .

  (9) The flow rate calculation unit 24B measures the propagation time in the blood of the ultrasonic signals transmitted and received between the pair of ultrasonic transducers 10A and 10B, respectively, and calculates the blood flow rate by the propagation time difference method. did. Thereby, compared with the case where the flow rate is calculated using the inverse propagation time difference method, the measurement accuracy can be maintained even when the resolution of the measurement of the propagation time is large.

  (10) The blood flow rate is calculated by the propagation time difference method using the sound velocity C corrected by the flow rate calculation unit 24B corresponding to the calculated concentration calculated by the concentration calculation unit 25. Thereby, the measurement accuracy of the flow rate can be further improved.

  (11) The extracorporeal circulation device 100B is further provided with notifying means 150 for notifying the abnormality when the calculated flow rate calculated by the flow rate calculating unit 24B is abnormal. Thereby, when an abnormality such as poor blood removal occurs, it is possible to promptly notify the medical staff.

  (12) The control board 160 included in the blood purification apparatus 100B is incorporated in the main body of the blood purification apparatus 100B, and the circuits constituting the measurement circuit 20B and the control unit 140B are mounted thereon. Thereby, since transmission and reception of signals with the flow rate calculation unit 24B and the concentration calculation unit 25 included in the measurement circuit 20B can be performed on the same substrate, a delay in information transmission between the measurement circuit 20B and the control unit 140B is reduced. be able to. Therefore, when the control unit 140B determines that there is an abnormality such as poor blood removal, it is possible to quickly perform control such as changing the set flow rate of the blood pump 111c or operating the notification unit 150. In addition, manufacturing costs can be reduced by mounting the circuits together on the same substrate.

Next, FIGS. 6A and 6B show the results of measuring the attenuation degree of the ultrasonic signal for blood with different concentrations using the ultrasonic measurement apparatus 1A and the blood purification apparatus 100A described in the first embodiment.
[Example 1]
Bovine blood at a temperature of 36 ° C., a hematocrit value of 30%, and 45% was passed through the blood circuit 110 at a set flow rate of 200 ml / min of the blood pump 111c, and the degree of attenuation of the ultrasonic signal was measured by the ultrasonic measurement apparatus 1A. Specifically, the waveform of the electrical signal transmitted by the transmission unit 21 (hereinafter referred to as a transmission waveform) and the waveform of the electrical signal received by the reception unit 22 (hereinafter referred to as a reception waveform) are compared. Thus, the degree of attenuation of the ultrasonic signal was calculated.
In the example, as shown in FIG. 7, the measurement site was a U-shaped pipe made of polypropylene having an inner diameter of 10 mm.
The ultrasonic transducers 10 </ b> A and 10 </ b> B are arranged at an interval of 10 mm in the blood flow direction of the blood circuit 110.
The transmission unit 21 is configured by an oscillation circuit capable of transmitting an electrical signal of several hundred kHz to several MHz using, for example, a ceramic vibrator, and the reception unit 22 generates a voltage based on the received weak ultrasonic signal. It consists of an amplifier circuit that amplifies.

  FIG. 6A shows a transmission waveform and a reception waveform when the hematocrit value is 30%, and FIG. 6B shows a transmission waveform and a reception waveform when the hematocrit value is 45%. The attenuation level of the ultrasonic signal was about 60% and about 40% when the hematocrit values were 30% and 45%, respectively, and it was found that the attenuation level increased as the blood concentration increased. Thus, since the attenuation level of the ultrasonic signal changes corresponding to the blood concentration, it is possible to calculate the blood concentration based on this correspondence and the attenuation level of the ultrasonic signal.

The preferred embodiments and examples of the ultrasonic measurement device and blood purification device of the present invention have been described above, but the present invention is not limited to the above-described embodiments and examples, and can be modified as appropriate. It is.
For example, in the above-described embodiment, a blood purification device that performs hemodialysis (HD) has been described as an example of an extracorporeal circulation device, but hemodialysis therapy such as blood filtration (HF) and blood filtration dialysis (HDF), plasma It can also be applied to blood purification devices that perform exchange therapy, blood adsorption therapy, and the like. It can also be applied to extracorporeal circulation devices such as an oxygenator.

  As an example of the flow rate calculation method in the ultrasonic measurement apparatus, the first embodiment shows the propagation time reciprocal difference method and the second embodiment shows the propagation time difference method. However, well-known methods such as the sing-around method and the Doppler method are used. A calculation method can be used.

  In addition, regarding the method of arranging the ultrasonic measuring device in the blood conduit, the first embodiment and the second embodiment have shown an example in which a pair of ultrasonic transducers are arranged so as to face each other diagonally, but this is not limitative. Absent. For example, a pair of ultrasonic transducers may be arranged and attached on the same side, or two pairs of ultrasonic transducers may be installed facing each other diagonally, or transmission / reception of ultrasonic signals is 1 A configuration in which two ultrasonic transducers are used may be used.

1A, 1B Ultrasonic Measuring Device 10A, 10B Ultrasonic Transceiver 20A, 20B Measuring Circuit 21 Transmitting Unit 22 Receiving Unit 23 Transmission / Reception Switching Unit 24A, 24B Flow Rate Calculation Unit 25 Concentration Calculation Unit 26 Storage Unit 100A, B Extracorporeal Circulation Device ( Blood purification device)
110 Blood circuit 111 Arterial line 111c Blood pump 112 Venous line 120 Blood purification means (dialyzer)
130 Dialysate circuit 140A, 140B Control unit 150 Notification means 160 Control board

Claims (7)

An ultrasonic measurement device used for an extracorporeal circulation device that circulates blood extracorporeally, comprising a blood circuit for flowing blood, and a blood purification means connected to the blood circuit and capable of removing water in the blood,
An ultrasonic transducer that is attached to the blood circuit, converts electrical signals and ultrasonic signals, and transmits and receives ultrasonic signals;
A measurement circuit that measures the flow rate and concentration of blood based on an ultrasonic signal transmitted and received by the ultrasonic transducer, and
The measurement circuit includes:
A transmitter for transmitting an electrical signal to the ultrasonic transducer;
A receiver for receiving an electrical signal from the ultrasonic transducer;
A flow rate calculation unit that calculates a blood flow rate based on a transmission signal transmitted by the transmission unit and a reception signal received by the reception unit;
A concentration calculation unit that calculates a blood concentration based on the degree of attenuation of the amplitude of the reception signal with respect to the amplitude of the transmission signal;
An ultrasonic measurement device comprising: The blood circuit includes an arterial line for flowing blood introduced into the blood purification means, and a venous side line for flowing blood derived from the blood purification means,
The ultrasonic measurement apparatus according to claim 1, wherein the ultrasonic transducer is attached to the artery-side line. The ultrasonic measurement device includes at least a pair of the ultrasonic transducers disposed opposite to each other with a predetermined distance in the flow direction of blood flowing through the blood circuit, with the blood circuit interposed therebetween,
The ultrasonic measurement apparatus according to claim 1, wherein the ultrasonic transducer transmits and receives an ultrasonic signal obliquely with respect to a blood flow direction.   The flow rate calculation unit measures a propagation time in blood of ultrasonic signals respectively transmitted and received between the pair of ultrasonic transducers, and calculates a blood flow rate by a reciprocal difference in propagation time. The ultrasonic measurement apparatus described. The ultrasonic measurement device according to any one of claims 1 to 4,
A blood circuit for flowing blood;
Blood purification means connected to the blood circuit and capable of removing water in the blood;
An extracorporeal circulation apparatus that circulates blood extracorporeally.   The extracorporeal circulation apparatus according to claim 5, further comprising a control unit that controls a water removal rate in the blood purification unit based on the calculated concentration calculated by the concentration calculation unit.   The extracorporeal circulation apparatus according to claim 5 or 6, further comprising notification means for notifying an abnormality when the calculated flow rate calculated by the flow rate calculation unit is abnormal.

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