JP5650881B2 - How to use the pressure sensor - Google Patents

Description

  The present invention relates to a method for using a pressure sensor.

  For example, extracorporeal circulation therapy, such as blood purification therapy, which takes out blood from a patient's body and processes it outside the body and returns it to the body, is performed using an extracorporeal circulation system having an extracorporeal circuit. The extracorporeal circulation system is provided with a pressure sensor that detects the pressure in the extracorporeal circulation circuit. This pressure sensor can detect an obstruction of the extracorporeal circuit due to blood coagulation or the like.

  As the above-described pressure sensor, for example, a sensor that indirectly detects the pressure in the extracorporeal circuit through a flexible diaphragm is employed in order to avoid generation of a thrombus due to contact between blood and air (patent) References 1 and 2).

  As shown in FIG. 7, the pressure sensor includes a gas chamber 201 defined by a flexible diaphragm 200 and a container 203 having a liquid chamber 202, and the gas chamber 201 of the container 203 is connected to the gas chamber 201. It has the detection part 204 which detects the pressure of this. A blood inlet 205 and an outlet 206 are formed in the liquid chamber 202 of the container section 203, and a vent 207 connected to the detection section 204 is formed in the gas chamber 201 of the container section 203. In this pressure sensor, the diaphragm 200 bends due to the pressure fluctuation of the liquid chamber 202 and the pressure of the gas chamber 201 fluctuates accordingly. Therefore, the pressure of the liquid chamber 202 is detected by detecting the pressure of the gas chamber 201 by the detection unit 204. Can be detected.

JP 2007-282996 A JP 2008-51663 A

  By the way, the container portion 203 of the pressure sensor usually needs to be replaced every time it is used because the blood of the patient flows. On the other hand, the detection unit 204 is expensive and is not touched by blood, so it usually does not need to be replaced. For this reason, the container part 203 and the detection part 204 are made detachable by, for example, an attachment / detachment mechanism using fitting, and when the pressure sensor is used, the vent 207 of the container part 203 is connected to the detection part 204 by the attachment / detachment mechanism. It is preferable to connect.

  However, in such a case, since the vent 207 of the container unit 203 and the detection unit 204 are connected by an attachment / detachment mechanism such as fitting, the gas in the gas chamber 201 gradually flows from the gap of the attachment / detachment mechanism, for example, when used at a positive pressure. It is conceivable that the external atmosphere gradually enters the gas chamber 201 from the gap of the attaching / detaching mechanism when leaking outside and using it under negative pressure. For this reason, for example, if the pressure sensor is continuously used for a long time, in the case of use at a positive pressure, the diaphragm 200 bends to the gas chamber 201 side even under the same pressure condition due to the outflow of the gas. In use, the diaphragm 200 bends toward the liquid chamber 202 even under the same pressure condition due to the inflow of gas, and the diaphragm 200 may eventually reach the limit of the movable range. When this happens, the diaphragm 200 does not move to one side in response to pressure fluctuations, so that the pressure cannot be detected accurately.

  The present invention has been made in view of the above points, and enables the pressure sensor to be continuously used for a longer time even when the container portion and the detection portion of the pressure sensor are connected by the attachment / detachment mechanism. It is an object to provide a method for using a pressure sensor.

To achieve the above object, the present invention provides a gas chamber in which a vent is formed, a liquid chamber connected to an extracorporeal circuit, a liquid chamber in which a liquid outlet is formed, the gas chamber, and the liquid chamber. And a container part provided with a flexible diaphragm that deforms according to a pressure difference between the gas chamber and the liquid chamber, and a vent of the gas chamber of the container part is connected by an attachment / detachment mechanism, and the gas A pressure sensor for detecting the pressure in the extracorporeal circuit, wherein the liquid chamber is brought into the atmosphere at the time of pressure detection. If become negative pressure against the in a state the diaphragm by the pressure adjustment in advance the liquid chamber is bent from the middle position in the gas chamber side, the liquid chamber is a positive pressure relative to the atmosphere when the pressure sensing In this case, the diaphragm is moved to the center position by adjusting the pressure of the liquid chamber in advance. In the state in which more flexed into the liquid chamber side, characterized by connecting the detector and the container portion of the vent.

  According to the present invention, for example, in the case of use at a negative pressure, even if outside air gradually enters the gas chamber from the gap of the attaching / detaching mechanism and the diaphragm is gradually bent toward the liquid chamber, the diaphragm is bent toward the gas chamber in advance. Therefore, it takes time for the diaphragm to reach the movable limit on the liquid chamber side. In addition, in the case of use at positive pressure, even if the gas in the gas chamber gradually escapes from the gap of the attachment / detachment mechanism and the diaphragm is gradually bent toward the gas chamber, the diaphragm is bent in advance toward the liquid chamber. It takes time for the diaphragm to reach the movable limit on the gas chamber side. As a result, the pressure sensor can be used continuously for a longer time.

When the pressure of the liquid chamber is P and the pressure of the gas chamber is P ₀ , the pressure of the liquid chamber may be adjusted so as to satisfy Expression (1).
0.6 kPa ≦ | P−P ₀ | ≦ 7 kPa (1)
In such a case, by setting the pressure difference between the liquid chamber and the gas chamber to be 0.6 kPa or more, it is possible to sufficiently ensure the bending of the diaphragm at the start of pressure detection, and it is possible to more reliably extend the continuous use time of the pressure sensor. . Further, by setting the pressure difference between the liquid chamber and the gas chamber to 7 kPa or less, it is possible to suppress the bending of the diaphragm more than necessary at the start of pressure detection and perform pressure detection with high accuracy.

  According to the present invention, the pressure sensor can be used continuously for a long time.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing an outline of the configuration of a blood purification system 1 provided with a pressure sensor according to the present embodiment.

  As shown in FIG. 1, the blood purification system 1 includes an extracorporeal circuit 2 through which a liquid such as blood flows and the extracorporeal circuit 2 are fixed to circulate the liquid in the extracorporeal circuit 2 or the extracorporeal circuit 2. It has a blood purification device 3 for adjusting the internal pressure.

  The extracorporeal circuit 2 has a blood circuit 11 that sends blood taken from a patient to the blood purifier 10 and returns it to the patient, for example. Inside the blood purifier 10, a separating material such as a hollow fiber membrane or an adsorbent for separating a predetermined component from blood according to the purpose is provided.

  For example, two pressure sensors A according to the present embodiment are provided on the blood collection unit side of the blood circuit 11 with respect to the blood collection unit.

  A drip chamber 40 for degassing blood is connected to the blood return side of the blood circuit 11 from the blood purifier 10.

  The blood purifier 10 is connected to branch circuits 50 and 51 for discharging separated components and returning or supplying necessary components to the blood purifier 10 according to the purpose.

  The blood purification apparatus 3 includes, for example, tube pumps 60, 61, 62, a detection unit 80 described later of the pressure sensor A, and the like.

  For example, the tube pump 60 is connected between the two pressure sensors A of the blood circuit 11. The tube pump 61 is connected to the branch circuit 50, and the tube pump 62 is connected to the branch circuit 51.

  In addition, the blood purification apparatus 3 controls the locking portion for locking the blood purifier 10 and the drip chamber 40 of the extracorporeal circuit 2, pressure detection by each pressure sensor A, and operation of the tube pumps 60 to 62. It has a control unit, an operation unit that can operate the entire system on the screen, and the like.

  According to this blood purification system 1, for example, blood purification therapy that purifies and returns blood taken from a patient can be performed.

  Next, the configuration of the pressure sensor A will be described. FIG. 2 is an explanatory diagram showing an outline of the configuration of the pressure sensor A.

  The pressure sensor A has, for example, a container part 70 and a detection part 80. A gas chamber 90 and a liquid chamber 91 are formed inside the container portion 70, and the gas chamber 90 and the liquid chamber 91 are partitioned by a flexible diaphragm 92. A liquid inlet 91 a and a liquid outlet 91 b are formed on the wall surface of the liquid chamber 91. The liquid inflow port 91a and the liquid outflow port 91b are formed on a wall surface in a direction perpendicular to the diaphragm 92 when viewed from the liquid chamber 91, for example. The liquid chamber 91 is connected to the blood circuit 11 through a liquid inlet 91a and a liquid outlet 91b. At the center of the wall surface 90a facing the diaphragm 92 of the gas chamber 90, a convex portion 90b protruding outward is formed. At the center of the projecting portion 90b, a vent 90c that leads from the gas chamber 90 to the outside is formed.

  The detection unit 80 is built in the blood purification apparatus 3. The detection part 80 can detect the pressure of the gas which contacted. The detection unit 80 is provided, for example, in a concave air passage 100 formed from the surface of the blood purification device 3 toward the inside. The convex part 90 b of the container part 70 can be fitted into the ventilation path 100. By inserting and fitting the convex portion 90b into the air passage 100, the vent 90c of the gas chamber 90 and the detection portion 80 are communicated with each other. Further, the convex portion 90b and the ventilation path 100 constitute an attachment / detachment mechanism for the container portion 70 and the detection portion 80, and the ventilation port 90c of the gas chamber 90 and the detection portion 80 can be connected by the attachment / detachment mechanism.

  The pressure sensor A can detect the pressure in the blood circuit 11 by detecting the atmospheric pressure of the gas chamber 90 which is deflected according to the liquid pressure in the liquid chamber 91 and fluctuates accordingly, by the detection unit 80.

Next, the usage method of the pressure sensor A comprised as mentioned above is demonstrated. First, before the vent 90c of the container part 70 of the pressure sensor A is connected to the detection part 80, the position of the deflection of the diaphragm 92 is adjusted. For example, when the pressure of the liquid chamber 91 in the container 70 becomes negative with respect to the atmosphere when the pressure is detected by the pressure sensor A later, the diaphragm 92 is moved from the center position C by adjusting the pressure of the liquid chamber 91 as shown in FIG. It is bent toward the gas chamber 90 side. The center position C is a position when the diaphragm 92 is flat and does not bend to either the liquid chamber 91 side or the gas chamber 90 side. Further, when the liquid chamber 91 becomes a positive pressure with respect to the atmosphere when the pressure is detected later, the diaphragm 92 is deflected from the central position C toward the liquid chamber 91 by adjusting the pressure of the liquid chamber 91 as shown in FIG. It is done. These pressure adjustments of the liquid chamber 91 are performed so as to satisfy the formula (1) when the pressure of the liquid chamber 91 is P and the pressure of the gas chamber 90 is P ₀ .
0.6 kPa ≦ | P−P ₀ | ≦ 7 kPa (1)

  In general, when the container part 70 is located on the upstream side of the tube pump, the liquid chamber 91 becomes negative pressure (use of negative pressure) during pressure detection, and the container part 70 is located on the downstream side of the tube pump. In this case, whether the liquid chamber 91 becomes positive pressure (positive pressure use) at the time of pressure detection becomes negative pressure or positive pressure is previously determined from the configuration of the extracorporeal circuit 2 or the like.

  Next, in a state where the deflection position of the diaphragm 92 is adjusted, the blood circuits 11 on both sides of the container part 70 are closed, and the deflection of the diaphragm 92 is maintained. In this state, as shown in FIGS. 5 and 6, the convex portion 90 b of the container portion 70 is inserted and fitted into the ventilation path 100 of the blood purification device 3. Thus, the vent 90c of the gas chamber 90 of the container unit 70 is connected to the detection unit 80 by the attachment / detachment mechanism. Thereafter, when negative pressure is used, pressure detection of the blood circuit 11 is started with the partition wall 92 bent toward the gas chamber 90 as shown in FIG. 5, and when positive pressure is used, as shown in FIG. With the partition wall 92 bent toward the liquid chamber 91, pressure detection of the blood circuit 11 is started.

  According to the present embodiment, for example, when negative pressure is used, outside air gradually enters the gas chamber 90 from the gap of the attachment / detachment mechanism between the container unit 70 and the detection unit 80, and the diaphragm 92 is on the liquid chamber 91 side ( Even if the diaphragm 92 is gradually moving in the direction of the dotted line arrow in FIG. 5, it takes time for the diaphragm 92 to reach the movable limit on the liquid chamber 91 side because the diaphragm 92 is bent to the gas chamber 90 side in advance. . Further, for example, when using positive pressure, even if the gas in the gas chamber 90 gradually escapes from the gap of the attachment / detachment mechanism and the diaphragm 92 moves to the gas chamber 90 side (in the direction of the dotted arrow in FIG. 6), Since the diaphragm 92 is bent toward the liquid chamber 91, it takes time for the diaphragm 92 to reach the movable limit on the gas chamber 90 side. For this reason, the pressure sensor A can be continuously used for a longer time.

  Moreover, in the said embodiment, when adjusting the bending position of the diaphragm 92, the pressure of the liquid chamber 91 is adjusted so that Formula (1) may be satisfy | filled. According to the inventor's experiment, when the pressure difference between the liquid chamber 91 and the gas chamber 90 is set to 0.6 kPa or more and the pressure measurement of the pressure sensor is continuously performed, the pressure measurement error (sensor reading value) It took 30 hours or more to reach ± 5% or more). As described above, by setting the pressure difference between the liquid chamber 91 and the gas chamber 90 to 0.6 kPa or more as in the formula (1), it is possible to sufficiently ensure the bending of the diaphragm 92 at the start of pressure detection. Continuous use time can be extended more reliably. Further, by setting the pressure difference between the liquid chamber 91 and the gas chamber 90 to 7 kPa or less, it is possible to suppress the bending of the diaphragm 92 more than necessary at the start of pressure detection, and to perform pressure detection with high accuracy. That is, when the diaphragm 92 moves in the vicinity of the central position C, pressure detection with relatively high accuracy can be performed. Therefore, by setting the position of the diaphragm 92 at the start of pressure detection to a position close to the central position C. Therefore, pressure detection with higher accuracy can be performed.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes or modifications can be made within the scope of the ideas described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  For example, the installation position and number of pressure sensors A in the extracorporeal circuit 2 of the above embodiment are not limited to this. Moreover, although the pressure sensor A was an example provided in the extracorporeal circuit 2 of the blood purification system in the above embodiment, the present invention is an extracorporeal circulation system having other configurations for performing treatments other than blood purification. The present invention can also be applied to a case where it is provided in an extracorporeal circuit. Further, the present invention can be applied even if the attachment / detachment mechanism between the container unit 70 and the detection unit 80 has another configuration.

It is the schematic which shows the structure of the blood purification system in this Embodiment. It is explanatory drawing which shows the outline of a structure of a pressure sensor. It is explanatory drawing of the pressure sensor which shows the position of the diaphragm in the case of negative pressure use. It is explanatory drawing of the pressure sensor which shows the position of the diaphragm in the case of positive pressure use. It is explanatory drawing of a pressure sensor when a container part is connected to a detection part by negative pressure use. It is explanatory drawing of a pressure sensor when a container part is connected to a detection part by positive pressure use. It is a schematic diagram of a pressure sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Blood purification system 2 Extracorporeal circuit 3 Blood purification apparatus 11 Blood circuit 70 Container part 80 Detection part 90 Gas chamber 90a Wall surface 90b Convex part 90c Vent 91 Liquid chamber 91a Liquid inlet 91b Liquid outlet 92 Diaphragm 100 Ventilation path A Pressure sensor

Claims (2)

A gas chamber formed with a vent; a liquid chamber connected to an extracorporeal circuit; a liquid chamber formed with a liquid outlet; the gas chamber and the liquid chamber being partitioned; and the gas chamber and the liquid chamber A container having a flexible diaphragm that deforms according to a pressure difference between the gas chamber, a vent of the gas chamber of the container, and an attachment / detachment mechanism, and the pressure of the liquid chamber via the pressure of the gas chamber And a method of using a pressure sensor that detects pressure in the extracorporeal circuit,
When the liquid chamber has a negative pressure with respect to the atmosphere at the time of pressure detection, the diaphragm is bent in advance from the center position toward the gas chamber by adjusting the pressure of the liquid chamber. When the pressure is positive with respect to the atmosphere, the diaphragm is bent in advance from the center position to the liquid chamber side by adjusting the pressure of the liquid chamber, and the vent of the gas chamber and the detection unit are How to use the pressure sensor, characterized by connecting (except for the method of adjusting pressure with the extracorporeal circuit connected to the patient) . 2. The pressure according to claim 1, wherein when the pressure of the liquid chamber is P and the pressure of the gas chamber is P ₀ , the pressure of the liquid chamber is adjusted so as to satisfy Equation (1). How to use the sensor.
0.6 kPa ≦ | P−P ₀ | ≦ 7 kPa (1)

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