JPWO2019181658A1 - Measurement system and calculation unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately calculate a pump lift of a centrifugal pump without adding a sensor for measuring a hematocrit value of blood or a sensor for measuring a blood temperature to a blood circuit. Provide a unit.
SOLUTION: This is a pump head calculation system in a blood circuit for circulating bleeding blood to the outside of a subject's body using a centrifugal pump, and has a pressure detecting unit for detecting the pressure downstream of the centrifugal pump and blood. A flow rate detection unit that detects the flow rate in the circuit, a rotation speed setting unit that sets the rotation speed of the centrifugal pump, a detection result of the pressure detection unit, a detection result of the flow rate detection unit, and a setting result of the rotation speed setting unit. Based on the above, it has a calculation unit for calculating the pump head according to a predetermined calculation formula.

Description

The present invention relates to a measurement system and a calculation unit for calculating the pump head of a centrifugal pump used in an extracorporeal circulation system.

Traditionally, extracorporeal circulation systems have been used to assist the patient's blood circulation and respiration during open heart surgery for heart disease and to temporarily sustain life against rapidly progressing circulatory insufficiency or cardiopulmonary arrest. ing.

The extracorporeal circulation system is incorporated into a blood circuit (extracorporeal circulation circuit) equipped with a blood removal route and a blood supply route, and an artificial lung that exchanges gas with blood, and aspiration of blood through the blood removal route and blood to the artificial lung It has a centrifugal pump that sends blood and a control unit that controls the operation of the extracorporeal circulation system (see, for example, Patent Document 1 below). The extracorporeal circulation system exchanges gas (adds oxygen to the blood and removes carbon dioxide) from the bleeding blood by an artificial lung, and sends the blood to the blood supply channel. In addition, the control unit provided in the extracorporeal circulation system controls the rotation speed of the centrifugal pump to adjust the pump head (discharge pressure) to a predetermined size when removing blood from the patient and sending blood to the artificial lung. To do.

Japanese Patent Application Laid-Open No. 2014-504906

It is generally known that the pump head is determined according to the flow rate of the liquid to be fed, the rotation speed of the pump, and the like. Further, when the target of liquid delivery is blood, it is known that the pump head is affected by the hematocrit value of blood and the temperature of blood in addition to the performance and operating conditions of the centrifugal pump. Therefore, in the extracorporeal circulation system, in order to accurately measure the pump head, it is necessary to add a sensor for measuring the hematocrit value of blood and a sensor for measuring the temperature of blood to the blood circuit. However, if these sensors are added to the blood circuit, the system configuration becomes complicated and the cost for constructing the system increases.

As a result of diligent studies, the inventors of the present invention have found a calculation formula capable of accurately calculating the pump head without being affected by the hematocrit value of blood or the temperature of blood. According to the present invention, it is possible to accurately calculate the pump lift of a centrifugal pump without adding a sensor for measuring the hematocrit value of blood or a sensor for measuring the temperature of blood to the blood circuit. Systems and computing units can be provided.

The measurement system according to one embodiment of the present invention is a pump head calculation system in a blood circuit that circulates bleeding blood to the outside of the body of the subject using a centrifugal pump, and detects the pressure downstream of the centrifugal pump. Pressure detection unit, flow rate detection unit that detects the flow rate in the blood circuit, rotation speed setting unit that sets the rotation speed of the centrifugal pump, detection result of the pressure detection unit, and detection of the flow rate detection unit. It has a calculation unit for calculating the pump head according to the following formula (a) based on the result and the setting result of the rotation speed setting unit.

In the above formula (a), P is the pump head (mmHg), Q is the flow rate (L / min), and w is the pump rotation speed (rpm).

Further, the measurement system in another embodiment of the present invention is a pump lift calculation system in a blood circuit that circulates bleeding blood to the outside of the body of the subject using a centrifugal pump, and is a pressure downstream of the centrifugal pump. A pressure detection unit that detects blood flow, a flow rate detection unit that detects the flow rate in the blood circuit, a rotation speed setting unit that sets the rotation speed of the centrifugal pump, a detection result of the pressure detection unit, and the flow rate detection unit. The pump lift is calculated based on the detection result of the above and the setting result of the rotation speed setting unit without considering the hematocrit value of the blood flowing in the blood circuit and the temperature of the blood. ..

Further, the calculation unit according to another embodiment of the present invention includes a centrifugal pump, a pressure detecting unit for detecting the pressure downstream of the centrifugal pump, a flow rate detecting unit for detecting the flow rate in the blood circuit, and the centrifugal pump. A pump head calculation unit used in a blood circuit that circulates blood that has been bleeding out of the body of the subject, and has a detection result of the pressure detection unit. The pump head is calculated by the following formula (a) based on the detection result of the flow rate detection unit and the setting result of the rotation speed setting unit.

In the above formula (a), P is the pump head (mmHg), Q is the flow rate (L / min), and w is the pump rotation speed (rpm).

According to the present invention, the pump head of the centrifugal pump can be calculated accurately without adding a sensor for measuring the hematocrit value of blood or a sensor for measuring the temperature of blood to the blood circuit. Therefore, it is possible to suppress the complicated system configuration and the increase in cost for system construction due to the addition of each of the above sensors.

It is a schematic diagram which shows the whole structure of the extracorporeal circulation system which concerns on embodiment of this invention. It is an overview perspective view of the centrifugal pump and the artificial lung which concerns on embodiment. It is an overview perspective view of the centrifugal pump which concerns on embodiment. It is a block diagram which shows the control system of the extracorporeal circulation system which concerns on embodiment. It is a graph which shows the comparison result of Example 1. FIG. It is a graph which shows the comparison result of Example 2. It is a graph which shows the comparison result of Example 3.

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. The following description does not limit the technical scope and meaning of terms described in the claims. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios.

FIG. 1 is a diagram showing an overall configuration of an extracorporeal circulation system 1 according to an embodiment. 2 and 3 are diagrams for explaining the centrifugal pump 20 included in the extracorporeal circulation system 1. FIG. 4 is a block diagram showing a control system of the extracorporeal circulation system 1.

The extracorporeal circulation system 1 according to the present embodiment is configured as a system that assists the blood circulation and respiration of the patient (subject) M.

As shown in FIG. 1, the extracorporeal circulation system 1 includes a blood circuit (extracorporeal circulation circuit) C that circulates blood bleeding from patient M outside the body, an artificial lung 10 that exchanges gas between blood, and a patient. A centrifugal pump 20 that circulates blood bleeding from the blood, a holder 30 that holds the artificial lung 10 and the centrifugal pump 20, and a pressure that detects pressure downstream of the centrifugal pump 20 (downstream in the blood flow direction in the blood circuit C). A detection unit 41, a flow rate detection unit 43 that detects the flow rate of blood flowing through the blood circuit C, a gas supply unit 60 that supplies gas to the artificial lung 10, and a bubble detection unit 70 that detects bubbles in the blood circuit C. It has a clamp 80 capable of blocking the blood flow path of the blood circuit C, a display 90 displaying predetermined information, and a controller 100.

Hereinafter, the configuration of each part of the extracorporeal circulation system 1 will be described.

(Blood circuit)
The blood circuit C includes a blood removal catheter C1 that removes blood from the vein of the patient M, a blood supply catheter C2 that sends blood toward the artery of the patient M, and a priming step (priming that removes air bubbles in the blood circuit C). ) Is provided with a switching unit C3 for switching the circuit when shifting to the extracorporeal circulation process of blood, and a tube C4 (see FIG. 2) for communicating the centrifugal pump 20 and the artificial lung 10.

As shown in FIG. 1, one end of the blood removal catheter C1 communicates with the vein of the patient M, and the other end communicates with the inflow port 21 (see FIG. 2) of the centrifugal pump 20 described later.

As shown in FIG. 1, one end of the blood feeding catheter C2 communicates with the artery of the patient M, and the other end communicates with the outflow port 13 (see FIG. 2) of the artificial lung 10 described later. The blood delivery catheter C2 sends the blood that has undergone gas exchange with the artificial lung 10 to the artery of the patient M.

The switching unit C3 forms a circulation circuit that does not pass through the body of the patient M during the priming step, and forms a circulation circuit that passes through the body of the patient M during the extracorporeal circulation step of blood. Note that FIG. 1 shows a state during the extracorporeal circulation process of blood.

(Artificial lung)
The artificial lung 10 is composed of a known membrane-type artificial lung that exchanges gas with blood by a hollow fiber. As shown in FIG. 2, the artificial lung 10 includes a cylindrical housing 11 that houses a gas exchange unit that exchanges gas with blood and a heat exchange unit that regulates the temperature of blood.

The housing 11 is provided with an inflow port (not shown) for allowing blood to flow into the housing 11 and an outflow port 13 for allowing blood flowing into the housing 11 to flow out of the housing 11. The housing 11 is preferably transparent to the extent that the internal blood flow is visible. The transparency includes colorless transparent, colored transparent, and translucent.

(Centrifugal pump)
As shown in FIGS. 2 and 3, the centrifugal pump 20 includes an inflow port 21 into which blood flows in, a rotating body 22 in which a linear flow path 22a through which blood flowing in from the inflow port 21 flows is formed, and blood. It has an outflow port 23 for outflowing the blood, and a casing 25 containing the rotating body 22.

As shown in FIG. 2, the casing 25 of the centrifugal pump 20 is connected to the drive motor 28 that transmits the rotational driving force to the rotating body 22 of the centrifugal pump 20. The inflow port 21 is connected to the blood removal catheter C1 (see FIG. 1). The outflow port 23 is connected to the inflow port (not shown) of the artificial lung 10 via a predetermined tube C4. As the drive motor 28, for example, a known one that magnetically couples with the rotating body 22 and transmits the rotational driving force to the rotating body 22 in a non-contact manner can be used.

The centrifugal pump 20 is composed of a closed impeller type pump. The centrifugal pump 20 guides the blood (see arrow a1 in FIG. 3) that has flowed into the casing 25 through the inflow port 21 to each flow path 22a. Further, the centrifugal pump 20 applies centrifugal force to the blood by rotating the rotating body 22 (see arrow r1 in FIG. 3) with the blood flowing into each flow path 22a, and the outflow port from each flow path 22a. Pump blood to 23. Blood is discharged into the blood circuit C via the outflow port 23 (see arrow a2 in FIG. 3).

The specific configuration of the centrifugal pump 20 is not particularly limited as long as blood can be sucked and discharged, and for example, known ones such as a semi-open impeller type, an open impeller type, a vortex type impeller, and a cone type impeller. It is possible to use. Of these, in order to calculate the pump head more accurately, it is preferable to use the closed impeller type.

(holder)
The holder 30 can be composed of, for example, a metal support member in which a pump holding portion for holding the centrifugal pump 20 and an artificial lung holding portion for holding the artificial lung 10 are integrally formed.

(Gas supply unit)
The gas supply unit 60 includes an oxygen cylinder, an air cylinder, and a gas blender (all not shown) that is airtightly connected to the oxygen cylinder and the air cylinder and supplies a mixed gas of oxygen and air to the artificial lung 10. Have.

(Bubble detector)
As shown in FIG. 1, the bubble detection unit 70 detects bubbles flowing through the blood feeding catheter C2. The bubble detection unit 70 is not particularly limited as long as it can detect bubbles flowing through the blood feeding catheter C2, but may be configured by, for example, an ultrasonic transmitter / receiver arranged across the blood feeding catheter C2 or an optical transmitter / receiver. it can.

(Clamp)
The clamp 80 is provided on the downstream side of the bubble detection unit 70, and can block the flow path of the blood feeding catheter C2. If a bubble is detected by the bubble detection unit 70 during the extracorporeal circulation of blood, the control unit 110 controls the clamp 80 to immediately block the flow path of the blood feeding catheter C2. This makes it possible to prevent air bubbles from flowing into the patient M's body.

(Pressure detector)
As shown in FIGS. 1 and 2, the pressure detection unit 41 is arranged between the centrifugal pump 20 and the artificial lung 10 in the blood circuit C. Specifically, the pressure detection unit 41 is attached to a tube C4 that connects the centrifugal pump 20 and the artificial lung 10. The pressure detection unit 41 measures the pressure of blood flowing through the tube C4 downstream of the centrifugal pump 20. The type (structure, etc.) of the pressure detection unit 41 is not particularly limited as long as the pressure of the fluid (liquid) can be measured, and can be configured by, for example, a known pressure sensor. Further, the location where the pressure detection unit is arranged is not particularly limited as long as the pressure downstream of the centrifugal pump 20 can be measured.

(Flow rate detector)
As shown in FIGS. 1 and 2, the flow rate detection unit 43 is arranged between the centrifugal pump 20 and the artificial lung 10 in the blood circuit C. Specifically, the flow rate detection unit 43 is attached to a tube C4 that connects the centrifugal pump 20 and the artificial lung 10. The flow rate detection unit 43 measures the flow rate of blood flowing through the tube C4 downstream of the centrifugal pump 20. The type (structure, etc.) of the flow rate detection unit 43 is not particularly limited as long as the flow rate of the fluid (liquid) can be measured, and can be configured by, for example, a known flow rate sensor. Further, the place where the flow rate detection unit is arranged is not particularly limited as long as the flow rate of blood (bleeding blood) flowing through the blood circuit C can be measured.

(display)
The display 90 displays information to be used for the operation of the extracorporeal circulation system 1. For example, the display 90 is an artificial lung acquired by the rotation speed of the centrifugal pump 20, the detection result (measurement result) of the pressure detection unit 41, the detection result (measurement result) of the flow rate detection unit 43, and the calculation result of the pump head described later. The velocity distribution of blood within 10 can be displayed.

(controller)
The controller 100 includes a control unit 110 that controls the operation of each part of the extracorporeal circulation system 1, and an operation unit 120 that can receive an instruction from the user to the extracorporeal circulation system 1.

The control unit 110 includes a CPU and a storage unit. The storage unit temporarily stores ROM for storing various programs and data, RAM for temporarily storing programs and data as a work area, image data for storing various programs and data, or image data obtained by image processing. It is equipped with a hard disk or the like used for saving in. A series of programs for executing the calculation of the pump head, which will be described later, can be stored in the storage unit in advance.

FIG. 4 is a block diagram that simply shows the control system of the control unit 110. The control unit 110 is electrically connected to the centrifugal pump 20, the pressure detection unit 41, the flow rate detection unit 43, the gas supply unit 60, the bubble detection unit 70, the clamp 80, the display 90, and the operation unit 120 via a bus or the like. doing.

The control unit 110 according to the present embodiment serves as a rotation speed setting unit 111 for setting the rotation speed of the centrifugal pump 20 and a calculation unit (corresponding to a calculation unit) 113 for calculating the pump head in a state where a predetermined program is executed. Has the function of. The rotation speed setting unit 111 controls the operation of the centrifugal pump 20 so that the centrifugal pump 20 rotates at a predetermined rotation speed set by the user via the operation unit 120. Further, the calculation unit 113 calculates the pump head of the centrifugal pump 20 based on the predetermined calculation formula (a) described later.

When a predetermined operation command is input by the user operating the operation unit 120, the control unit 110 controls the operation of each part of the extracorporeal circulation system 1 based on the operation command. Further, the control unit 110 performs detection and measurement by each part of the extracorporeal circulation system 1, and when the detection result and the measurement result are transmitted, the operation control of each part of the extracorporeal circulation system 1 is performed according to a program stored in advance. I do. The method of calculating the pump head by the measurement system incorporated in the extracorporeal circulation circuit will be described below.

(Measurement system)
The measurement system according to the present embodiment includes a pressure detection unit 41, a flow rate detection unit 43, a rotation speed setting unit 111, and a calculation unit 113.

The calculation unit 113 uses the following formula (a) to lift the pump based on the detection result of the pressure detection unit 41, the detection result of the flow rate detection unit 43, and the setting result (set rotation speed) of the rotation speed setting unit 111. To calculate. In the following formula (a), P is the pump head (mmHg), Q is the flow rate (L / min), and w is the pump rotation speed (rpm).

By calculating the pump head of the centrifugal pump 20 by the above formula (a), the measurement system does not detect the hematocrit value and temperature of the blood flowing through the blood circuit C while operating the extracorporeal circulation system 1. The pump head can be calculated.

In the above formula (a), the term (5.3 exp (−Q) or 0.5 Q ² ) including the flow rate (Q) is set in advance without acquiring the operating state of the extracorporeal circulation system 1. A predetermined constant may be used.

5 to 7 show the comparison result between the calculation result of the above formula (a) and the actually measured value as Examples 1 to 3. The measurement system according to the present invention is not limited to use under the conditions of the examples described below.

In the example, a closed impeller type centrifugal pump 20 was used. The flow rate was measured by a flow rate sensor arranged on the downstream side (blood feeding side) of the centrifugal pump 20 as in the configuration example shown in FIG. The pump head (measured value) of the centrifugal pump 20 is determined by arranging pressure sensors on the upstream side (blood removal side) of the centrifugal pump and the downstream side (blood feeding side) of the centrifugal pump and by the difference between the measured values of each pressure sensor. did.

Three types of porcine blood having a hematocrit value (Hct) = 25.9, 34.1, and 53.3 were prepared as blood to be passed through the blood circuit. The measurement result of hematocrit value (Hct) = 25.9 is shown in FIG. 5 as Example 1. The measurement result of hematocrit value (Hct) = 34.1 is shown in FIG. 6 as Example 2. The measurement result of hematocrit value (Hct) = 53.3 is shown in FIG. 7 as Example 3.

In each example, the flow rate and pump head at the time when the centrifugal pump 20 was rotated at 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, and 3000 rpm were sampled. Sampling was performed once per second under the same conditions. The actually measured values shown in FIGS. 5 to 7 (measured values are indicated by ●, ○, ▲, Δ, and ◇ in the figure) are average values of the measurement results measured five times or more. Further, each broken line shown in FIGS. 5 to 7 is a theoretical value calculated by inputting the flow rate and the pump rotation speed into the above-mentioned formula (a).

From the results of Examples 1 to 3, it was confirmed that the difference between the measured pump head measured at each hematocrit value and the pump head calculated by the formula (a) was 5% or less. Therefore, it was confirmed that the pump head can be calculated accurately without being affected by the hematocrit value by using the formula (a). Further, it can be confirmed that the difference between the calculation results of each pump head calculated by the formula (a) is 10% or less in the comparison of the calculation results under the same conditions (the same flow rate and the same pump rotation speed). It was. Therefore, it was also confirmed that the pump head can be measured with an error of 10% or less by using the formula (a).

Further, in the measurement system according to the present invention, the centrifugal pump 20 is calculated by calculating the difference between the detection result (actual measurement value) of the pressure detection unit 41 provided on the downstream side of the centrifugal pump 20 and the calculation result of the formula (a). Blood pressure loss on the upstream side of the can be measured. Therefore, in the extracorporeal circulation system 1, it is not necessary to install a pressure detection unit on the upstream side of the centrifugal pump 20, so that the system configuration becomes simpler.

Although the measurement system according to the present invention has been described above through the embodiments, the present invention is not limited to each of the described configurations, and can be appropriately modified based on the description of the scope of claims.

For example, the configuration of the extracorporeal circulation system (arrangement of each member, etc., type of each member, etc.) is not particularly limited as long as the lift of the centrifugal pump can be calculated by the measurement system, and can be changed as appropriate. For example, the calculation unit (a calculation unit generally called a data management system) does not have to be integrated into the extracorporeal circulation system, and may be provided in an external communication device or the like.

This application is based on Japanese Patent Application No. 2018-053196 filed on March 20, 2018, the disclosure of which is cited in its entirety by reference.

1 Extracorporeal circulation system,
10 artificial lung,
20 Centrifugal pump,
21 Inflow port,
22 rotating body,
22a channel,
23 Outflow port,
25 casing,
41 Pressure detector,
43 Flow rate detector,
110 control unit,
111 rpm setting unit,
113 Calculation unit (calculation unit),
C blood circuit,
M patient (subject).

Claims (6)

A pump head calculation system in a blood circuit that circulates bleeding blood from the subject's body using a centrifugal pump.
A pressure detector that detects the pressure downstream of the centrifugal pump,
A flow rate detection unit that detects the flow rate in the blood circuit and
A rotation speed setting unit for setting the rotation speed of the centrifugal pump, and a rotation speed setting unit.
It has a calculation unit that calculates the pump head by the following formula (a) based on the detection result of the pressure detection unit, the detection result of the flow rate detection unit, and the setting result of the rotation speed setting unit. Measurement system.

In the above formula (a), P is the pump head (mmHg), Q is the flow rate (L / min), and w is the pump rotation speed (rpm). The measurement according to claim 1, wherein the calculation unit calculates blood pressure loss on the upstream side of the centrifugal pump based on the detection result of the pressure detection unit and the calculation result calculated by the formula (a). system. The centrifugal pump has an inflow port into which blood flows in, a rotating body in which a linear flow path for flowing the blood flowing in from the inflow port is formed, an outflow port through which the blood flows out, and the rotating body. The measuring system according to claim 1 or 2, further comprising a contained casing. The measurement system according to any one of claims 1 to 3, wherein the centrifugal pump is a closed impeller type pump. A pump head calculation system in a blood circuit that circulates bleeding blood from the subject's body using a centrifugal pump.
A pressure detector that detects the pressure downstream of the centrifugal pump,
A flow rate detection unit that detects the flow rate in the blood circuit and
A rotation speed setting unit for setting the rotation speed of the centrifugal pump, and a rotation speed setting unit.
Based on the detection result of the pressure detection unit, the detection result of the flow rate detection unit, and the setting result of the rotation speed setting unit, without considering the hematocrit value and the blood temperature of the blood flowing in the blood circuit. , A measurement system having a calculation unit for calculating the pump head. Centrifugal pump and
A pressure detection unit that detects the pressure downstream of the centrifugal pump,
A flow rate detection unit that detects the flow rate in the blood circuit and
A pump head calculation unit used in a blood circuit that circulates bleeding blood to the outside of the subject's body, which has a rotation speed setting unit for setting the rotation speed of the centrifugal pump.
A calculation unit that calculates the pump head by the following formula (a) based on the detection result of the pressure detection unit, the detection result of the flow rate detection unit, and the setting result of the rotation speed setting unit.

In the above formula (a), P is the pump head (mmHg), Q is the flow rate (L / min), and w is the pump rotation speed (rpm).