Pressure control device, pressure control system, and pressure control method

Abstract

This pressure control device comprises: a first tube 11 that communicates with a lumen inside the body of a subject; a pressure sensor 14 that is installed in the first tube and measures the pressure of a gas; a first valve 12 that is installed in the first tube and releases the gas to the atmosphere; and a controller 15 that controls the opening of the first valve on the basis of the pressure.

Description

Pressure control device, pressure control system, and pressure control method

[0001] Embodiments of the present invention relate to a pressure control device for use in measuring the pressure of a lumen in a subject's body, a pressure control system including a pressure control device for use in measuring the pressure of a lumen in a subject's body, and a method for controlling the pressure of a lumen in a subject's body.

[0002] Gastroesophageal reflux disease (hereinafter referred to as "GERD") is a functional disorder in which, for example, the function of the gastric cardia is impaired, causing gastric juice to reflux into the esophagus. Methods for diagnosing GERD (hereinafter referred to as "GERD diagnostic methods") include 24-hour esophageal pH monitoring and 24-hour esophageal impedance pH monitoring.

[0003] As a method for diagnosing GERD, a method of observing the relaxation state of the lower esophageal sphincter (LES) in the cardiac region of the stomach using an endoscope is being adopted in order to reduce the burden on the subject.

[0004] International Publication No. 2021 / 166127 discloses an endoscopic system that supplies gas into a subject's lumen while measuring the pressure within the lumen and diagnoses GERD based on the pattern of pressure changes.

[0005] Another esophageal dysfunction is achalasia, which occurs when abnormalities occur in the function of the lower esophageal sphincter, making it difficult for food to pass from the esophagus to the stomach, which is the opposite of GERD.

[0006] International Publication No. 2021 / 166127

[0007] If the pressure in the lumen increases excessively, there is a risk that the subject will be put under a lot of strain.

[0008] An embodiment of the present invention aims to provide a pressure control device that reduces the burden on a subject during an examination, a pressure control system that includes a pressure control device that reduces the burden on a subject, and a pressure control method that reduces the burden on a subject.

[0009] A pressure control device according to one embodiment of the present invention comprises a first tube communicating with a lumen in a subject's body, a pressure sensor disposed in the first tube for measuring the pressure of a gas, a first valve disposed in the first tube for releasing the gas to the atmosphere, and a controller for controlling the opening of the first valve based on the pressure.

[0010] A pressure control system according to one aspect of the present invention includes an endoscope having an air / water supply pipe and a forceps channel passing through an insertion portion, the insertion portion of which is inserted into a lumen of a subject, a first tube connected to communicate with the forceps channel, a pressure sensor disposed in the first tube for measuring gas pressure, a first valve disposed in the first tube for releasing the gas to the atmosphere, a second valve disposed in the second tube for releasing the gas to the atmosphere, and a controller for controlling the opening of at least one of the first valve or the second valve when the pressure reaches a first pressure.

[0011] A pressure control method according to one aspect of the present invention includes connecting a first tube to a forceps channel of an endoscope having an air and water pipe passing through an insertion portion thereof and the forceps channel, connecting a second tube to the air and water pipe, inserting the insertion portion of the endoscope into a lumen of a subject, supplying gas from a gas supply source to the lumen via the second tube and the air and water pipe, measuring the pressure of the gas using a pressure sensor disposed in the first tube, and when the pressure reaches a first pressure, controlling the opening of at least one of a first valve disposed in the first tube and a second valve disposed in the second tube, thereby releasing the gas in the lumen to the atmosphere.

[0012] According to an embodiment of the present invention, it is possible to provide a pressure control device that reduces the burden on a subject during an examination, a pressure control system that includes a pressure control device that reduces the burden on a subject, and a pressure control method that reduces the burden on a subject.

[0013] FIG. 1 is a diagram illustrating the overall configuration of a pressure control system including a pressure control device according to an embodiment of the present invention. FIG. 2 is a diagram illustrating the configuration of a pressure control system including a pressure control device according to an embodiment of the present invention. FIG. 3 is a flowchart of a pressure control method according to a first embodiment of the present invention. FIG. 4 is a graph showing pressure changes in the lumen of a GERD subject according to an embodiment of the present invention. FIG. 5 is a graph showing pressure changes in the lumen of a healthy subject according to an embodiment of the present invention. FIG. 6 is a graph showing pressure changes in the lumen of an achalasia patient according to a conventional control system. FIG. 7 is a graph showing pressure changes in the lumen of an achalasia patient according to an embodiment of the present invention. FIG. 8 is a diagram illustrating the configuration of a pressure control system including a pressure control device according to a second embodiment of the present invention. FIG. 9 is a flowchart of a pressure control method according to the second embodiment of the present invention.

[0014] Hereinafter, embodiments will be described with reference to the drawings. The drawings based on the embodiments are schematic. The relationship between the thickness and width of each part in the drawings, the thickness ratio of each part, etc., differ from the actual ones. The drawings also include parts with different dimensional relationships and ratios. Some components will not be shown or labeled.

[0015] First Embodiment A pressure control system 1 of this embodiment shown in FIG. 1 includes an endoscope 9 , a pressure control device 10 , an air supply unit 20 , a display 31 , a video processor 43 , and a light source 41 .

[0016] The endoscope 9 includes an elongated insertion section 93 that is inserted into the subject, an operating section 94 provided at the proximal end of the insertion section 93, a universal cord 95 extending from the operating section 94, and a connector 96. The operating section 94 includes a bending operation knob and a plurality of buttons for operating the endoscopic functions. The insertion section 93 of the endoscope 9 includes, in order from the distal end, a distal end 93A, a freely bendable bending section 93B provided at the proximal end of the distal end 93A, and an elongated flexible tube 93C provided at the proximal end of the bending section 93B. Although not shown, the distal end 93A is provided with an imaging unit, an illumination optical system, and an opening for a forceps channel 91 ( FIG. 2 ). The forceps channel 91 is a tube that passes through the insertion section 93 from an insertion port 97 of the operating section 94 to the opening of the distal end 93A.

[0017] The connector 96 is connected to the optical fiber bundle 42 of the light source 41, the cable 44 of the video processor 43, and the second tube (air supply tube) 21 of the air supply unit 20. Illumination light generated by the light source 41 is guided via the optical fiber bundle 42 to the illumination optical system of the distal end 93A. In response to button operation of the operation unit 94, the air supply unit 20 ejects a fluid (gas or liquid) from an opening in the distal end 93A via the universal cord 95, the operation unit 94, and an air / water supply tube 92 ( FIG. 2 ) passing through the insertion unit 93. In other words, the air supply unit 20 is an air / water supply unit capable of supplying not only gas but also liquid, but in the description of the present invention, only gas is used as the fluid. Air / water supply can be switched by operating the button of the operation unit 94. The second tube 21 may be connected to the operation unit 94.

[0018] The video processor 43 processes the image pickup signal from the imaging unit of the distal end portion 93A and displays an endoscopic image on the display 31.

[0019] The pressure control system 1 of this embodiment is configured by adding a pressure control device 10 to the above-described endoscope system.

[0020] As shown in FIG. 2, the pressure control device 10 includes a first tube 11 , a first valve 12 , a first filter 13 , a pressure sensor 14 , a controller 15 , and a memory 16 .

[0021] The first tube 11 is connected to an insertion port 97 of a forceps channel 91 of the endoscope 9. When a tip portion 93A of the insertion section 93 of the endoscope 9 is inserted into a stomach 100, which is a lumen of the subject, the first tube 11 communicates with the inside of the stomach 100 via the forceps channel 91. A first valve 12, a first filter 13, and a pressure sensor 14 are disposed in the first tube 11.

[0022] The first valve 12 is a relief valve that releases the gas in the first tube 11 to the atmosphere. The pressure sensor 14 measures the pressure of the gas in the first tube 11. Since the first tube 11 is in communication with the stomach 100, the first valve 12 releases the gas in the stomach 100 to the atmosphere, and the pressure sensor 14 measures the pressure of the gas in the stomach 100. A first filter 13, which prevents contamination of the pressure sensor 14, is disposed in a position closer to the stomach 100 than the pressure sensor 14.

[0023] For example, a controller 15 including a CPU controls the entire pressure control system 1. A memory 16 stores setting conditions of the pressure control system 1 and the like.

[0024] The air supply unit 20 has a second tube 21, a pressure vessel 24, and a valve 26. The second tube 21 is connected to an air and water supply pipe 92 of the endoscope 9. When a tip portion 93A of an insertion section 93 of the endoscope 9 is inserted into a stomach 100, which is a lumen of the subject, the second tube 21 communicates with the inside of the stomach 100 via the air and water supply pipe 92.

[0025] Gas, for example, carbon dioxide gas, supplied from a cylinder 25 serving as a gas supply source is decompressed by a regulator (not shown) and sent to the second tube 21 via a pressure vessel 24 .

[0026] The pressure control system 1 diagnoses GERD and achalasia by measuring the gas pressure (internal pressure) within the stomach 100 while supplying gas from the gas supply unit 20 via the endoscope 9 into the stomach 100 of the subject. The pressure data is displayed in chronological order on the display 31. The display 31 displays the pressure data together with the endoscopic image, but may also be a display dedicated to pressure data. The speaker 32 notifies the user by voice, for example, of the occurrence of an abnormality.

[0027] The allowable pressure of gas in stomach 100 is set to a first pressure P1 that causes extreme discomfort to the subject. As will be described later, when the pressure reaches first pressure P1, controller 15 controls valve 26 to close so that gas supply unit 20 stops supplying gas. However, the pressure of gas in second tube 21 and the pressure vessel 24 are higher than first pressure P1, which is the pressure of gas in stomach 100. For this reason, even after valve 26 is controlled to close, gas may continue to be supplied to stomach 100, causing the internal pressure to exceed first pressure P1.

[0028] In the pressure control system 1, when the internal pressure reaches the first pressure P1, not only is the valve 26 controlled to close, but the first valve 12 is also controlled to open. Because there is no risk of the internal pressure greatly exceeding the first pressure P1, the pressure control system 1 can reduce the burden on the subject.

[0029] <Pressure Control Method> A pressure control method by the pressure control system 1 will be described with reference to the flowchart of FIG.

[0030] <Step S10> Tube Connection The first tube 11 is connected to the insertion port 97 of the forceps channel 91 of the endoscope 9. The second tube 21 is connected to the air / water supply pipe 92 of the endoscope 9.

[0031] <Step S11> Insertion The distal end portion 93A of the insertion section 93 of the endoscope 9 is inserted into the stomach 100 of the subject. Note that the cardia may be observed using an imaging unit provided at the distal end portion 93A.

[0032] <Step S12> Start of gas supply The controller 15 controls the valve 26 of the gas supply unit 20 to supply gas into the stomach 100. The valve 26 is, for example, a type of solenoid valve, and has an adjustment valve using an electromagnetic coil in the drive unit. When a current is passed through the electromagnetic coil, a magnetic force is generated, which attracts the plunger and moves the valve. The opening of the valve is controlled by the magnitude of the current passed through the electromagnetic coil, and the flow rate of gas is adjusted to a predetermined value.

[0033] <Step S13> First time course? Figure 4 shows the change in intragastric pressure with respect to the insufflation time in a patient with GERD, whose gastric cardia function is impaired. Note that intragastric pressure reflects respiratory fluctuations and is higher during inspiration than during expiration. Therefore, the measured pressure repeatedly increases and decreases according to the respiratory cycle.

[0034] In a GERD patient, even if air is supplied into the stomach 100, gas continues to leak from the cardia. Therefore, even after a predetermined first time T1 has elapsed since the start of air supply, the pressure P does not reach the reference pressure P0. The reference pressure P0 is the GERD diagnostic pressure. The first time T1 and the reference pressure P0 are set appropriately; for example, T1 is 5 minutes and P0 is 16 mmHg.

[0035] When the first time T1 has elapsed since the start of gas supply (S13, YES), the process proceeds to step S14.

[0036] <Step S14> Stopping Air Supply Air supply from the air supply unit 20 is stopped and the process ends under the control of the controller 15. Note that when stopping air supply, the controller 15 may control the air supply unit 20 to reduce the air supply flow rate to a predetermined flow rate and then completely stop air supply.

[0037] <Step S15> Pressure decrease due to burping? Figure 5 shows the change in intragastric pressure with respect to the time of insufflation in a healthy subject. The pressure gradually increases, but when it reaches pressure PM (time TM), the gas in the stomach 100 is released through the mouth by burping, and the pressure suddenly decreases.

[0038] When the controller 15 detects that the pressure has dropped suddenly (YES), the process proceeds to step S14.

[0039] <Step S16> Pressure≧Reference Pressure? The process from step S13 is repeated until the pressure exceeds the reference pressure P0.

[0040] <Step S17> Pressure drop due to burping? If the pressure PM when the pressure drops due to burping exceeds the reference pressure P0, the subject is diagnosed as not having GERD. In a healthy subject, the burping pressure PM is, for example, greater than 18 mmHg and less than 25 mmHg.

[0041] <Step S18> Pressure ≧ First Pressure? In achalasia patients, the pressure rises above the burp pressure PM of a healthy individual due to abnormalities in the function of the lower esophageal sphincter. For example, if the burp pressure PM exceeds 20 mmHg, achalasia is diagnosed. To assess the severity of achalasia, air is further delivered until the pressure exceeds the first pressure P1.

[0042] 6 shows the change in pressure over time in an achalasia patient using a conventional pressure control system. In a severe achalasia patient, even when the pressure reaches first pressure P1 at time TF, which is the tolerable pressure at which the subject feels extremely uncomfortable, the gas in stomach 100 is not released by burping. To reduce the burden on the subject, valve 26 is controlled to close, and gas delivery from gas delivery unit 20 is stopped. First pressure P1 is determined appropriately depending on the subject's condition (age, gender, etc.), but is, for example, 25 mmHg or higher.

[0043] Even if valve 26 is controlled to be closed, the gas remaining in second tube 21 and pressure vessel 24 will flow into stomach 100 because their pressures are higher than the internal pressure of stomach 100. Therefore, even if valve 26 is controlled to be closed at time TF, the pressure will rise above first pressure P1 and then gradually decrease. That is, there is a risk that the pressure will exceed first pressure P1, which is the allowable pressure.

[0044] On the other hand, in the pressure control device 10, when the pressure reaches the predetermined first pressure P1 (YES), the process of the controller 15 proceeds to step S19.

[0045] <Step S19> Stopping Air Supply and Opening First Valve When the pressure reaches the first pressure P1 at time TF, the controller 15 not only stops the air supply from the air supply unit 20 by controlling the valve 26 to close, but also controls the first valve 12 to open. As a result, the pressure drops sharply, as shown in Fig. 7. The pressure control device 10 prevents the pressure from exceeding the first pressure P1, which is the allowable pressure, and therefore reduces the burden on the subject.

[0046] When the first valve 12 is opened, the internal pressure drops suddenly, which may cause gastric juices and the like to flow into the first tube 11 along with the gas, contaminating the pressure sensor 14 and the like. For this reason, it is preferable for the controller 15 to control the first valve 12 so that it repeatedly opens and closes, rather than controlling the first valve 12 so that it remains open continuously. For example, the controller 15 controls the first valve 12 so that it opens for 0.5 seconds and closes for 0.5 seconds. By controlling the opening and closing, a sudden drop in internal pressure can be prevented. The respective times (open time / close time) are selected as appropriate.

[0047] The first filter 13, which is used to reliably prevent contamination of the pressure sensor 14, is a disposable part, and is preferably replaced together with the first tube 11 located distal to the first filter 13 after each use.

[0048] As described above, the pressure control device 10 of this embodiment comprises a first tube 11 communicating with a lumen inside the subject's body, a pressure sensor 14 arranged in the first tube 11 for measuring the pressure of the gas, a first valve 12 arranged in the first tube 11 for releasing the gas to the atmosphere, and a controller 15 for controlling the opening of the first valve 12 based on the pressure.

[0049] As described above, the pressure control system 1 of this embodiment includes an endoscope 9 having an air / water supply pipe 92 and a forceps channel 91 through which an insertion portion 93 is inserted, the insertion portion 93 being inserted into a lumen of a subject, a first tube 11 connected to communicate with the forceps channel 91, a pressure sensor 14 disposed in the first tube 11 for measuring the pressure of the gas, a first valve 12 disposed in the first tube 11 for releasing the gas to the atmosphere, and a controller 15 for controlling the opening of the first valve 12 when the pressure reaches a first pressure P1.

[0050] In the pressure control method of the embodiment, a first tube 11 is connected to a forceps channel 91 of an endoscope 9 having an air and water supply pipe 92 and a forceps channel 91 through which an insertion portion 93 is inserted, a second tube 21 is connected to the air and water supply pipe 92, the insertion portion 93 of the endoscope 9 is inserted into a lumen of a subject, gas is supplied to the lumen from a gas supply source via the second tube 21 and the air and water supply pipe 92, the pressure of the gas is measured using a pressure sensor 14 arranged in the first tube 11, and when the pressure reaches a first pressure P1, a first valve 12 arranged in the first tube 11 is controlled to open, and the gas in the lumen is released to the atmosphere.

[0051] According to this embodiment, it is possible to provide a pressure control device that reduces the burden on the subject during an examination, a pressure control system that includes a pressure control device that reduces the burden on the subject, and a pressure control method that reduces the burden on the subject.

[0052] The above has described the pressure control system 1 used to diagnose GERD and esophageal achalasia, taking the stomach 100 as an example of a lumen of a subject. However, the lumen is not limited to the stomach 100, and may be a lumen into which gas is supplied, such as the large intestine.

[0053] Second Embodiment Pressure control systems 1A and 1B described below are similar to and have the same effects as the pressure control system 1. For this reason, in the following, components having the same functions as those in the pressure control system 1 are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0054] 8, the gas supply unit 20A of the pressure control system 1A of this embodiment is equipped with a second valve 22 and a second filter 23 disposed in the second tube 21. The second valve 22 is a relief valve similar to the first valve 12, and releases the gas in the second tube 21 to the atmosphere. The second valve 22 is disposed between the second filter 23 of the second tube 21 and the valve 26, for example, in the pressure vessel 24. The second filter 23, which prevents contamination of the pressure vessel 24 and the valve 26, is disposed in a position closer to the stomach 100 than the pressure vessel 24 and the valve 26.

[0055] The configuration of the pressure control system 1A described above is merely an example, and the present invention is not limited to the above configuration. For example, the second tube 21 provided with the second filter 23 and the second valve 22 may be attached to the pressure vessel 24 of a general-purpose endoscope system to form the air supply unit 20A.

[0056] The pressure control method by the pressure control system 1A shown in FIG. 9 is the same as the pressure control method by the pressure control system 1 shown in FIG. 3 from step S10 to step S19, and therefore description thereof will be omitted.

[0057] <Step S20> Decrease Rate≦First Rate The controller 15 determines whether the pressure decrease rate ΔP / s is slower than a predetermined first rate ΔP1 / s. If the decrease rate ΔP / s is faster than the predetermined first rate ΔP1 / s (NO), the controller 15 ends the process. The first rate ΔP1 / s is set appropriately, for example, to 5 mmHg / s.

[0058] However, for example, if the first filter 13 becomes clogged with an unexpectedly large amount of filth, there will be a delay in the release of gas via the first valve 12. Continuing this high pressure state will be painful for the subject. If the rate of decrease ΔP / s is slower than the predetermined first rate ΔP1 / s (YES), the control of the controller 15 proceeds to step S20.

[0059] <Step S20> Second Valve Open Control The controller 15 controls to open the second valve 22 of the gas supply unit 20A. By releasing the gas in the second tube 21 to the atmosphere, the gas in the stomach 100 is also released to the atmosphere via the second valve 22. Therefore, the pressure control system 1A can diagnose GERD and achalasia more reliably than the pressure control system 1A and without causing discomfort to the subject.

[0060] If the second valve 22 is opened, gastric juices and the like may flow into the second tube 21 along with the gas, potentially contaminating the pressure vessel 24. For this reason, it is preferable for the controller 15 to repeatedly open and close the second valve 22 rather than controlling it to a continuous open state. For example, the controller 15 controls the second valve 22 so that it is open for 0.5 seconds and closed for 0.5 seconds.

[0061] The second filter 23, which is provided to reliably prevent contamination, may become contaminated when the second valve 22 is opened. Therefore, when the controller 15 controls the second valve 22 to be open, it is preferable that the controller 15 generates a signal instructing the user to replace the second filter 23. The instruction signal is transmitted to the user by the display 31 and the speaker 32.

[0062] Although not shown, the controller 15 of the pressure control system 1B of this modification controls to open the second valve 22, rather than the first valve 12, in step S18 of the flowchart shown in Fig. 9. Then, in step S19, the controller 15 controls to open the first valve 12, rather than the second valve 22.

[0063] That is, when the pressure exceeds the first pressure P1, the controller 15 controls the second valve 22 to open. Then, when the rate of pressure drop after controlling the second valve 22 to open is less than the first rate, the controller 15 controls the first valve 12 to open.

[0064] The present invention is not limited to the above-described embodiments, and various modifications, combinations, and applications are possible within the scope of the invention.

[0065] DESCRIPTION OF SYMBOLS 1, 1A, 1B... Pressure control system 9... Endoscope 10... Pressure control device 11... First tube 12... First valve 13... First filter 14... Pressure sensor 15... Controller 16... Memory 20... Air supply unit 21... Second tube (air supply tube) 22... Second valve 23... Second filter 24... Pressure vessel 25... Cylinder 26... Valve 31... Display 32... Speaker 41... Light source 42... Optical fiber bundle 43... Video processor 44... Cable 91... Forceps channel 92... Air and water supply tube 93... Insertion section 93A... Tip 93B... Bending section 93C... Flexible tube 94... Operation section 95... Universal cord 96... Connector 97... Insertion port 100... Stomach

Claims

1. A pressure control device comprising: a first tube communicating with a lumen in a subject; a pressure sensor disposed in the first tube for measuring the pressure of a gas; a first valve disposed in the first tube for venting the gas to the atmosphere; and a controller for controlling the opening of the first valve based on the pressure.

2. The pressure control device according to claim 1, wherein the controller controls the opening of the first valve when the pressure reaches a first pressure.

3. The pressure control device according to claim 1, further comprising: a second tube communicating with the lumen for supplying the gas from a gas supply source to the lumen; and a second valve disposed in the second tube for venting the gas to the atmosphere, wherein the controller controls the opening of the first valve and the second valve based on the pressure.

4. The pressure control device according to claim 3, wherein the controller controls the opening of the second valve based on a change in the pressure after the first valve is controlled to open.

5. The pressure control device according to claim 3, wherein the controller controls the opening of the second valve when a rate of pressure drop after the first valve is controlled to open is less than a first rate.

6. The pressure control device according to claim 1, having a first filter at a position closer to the lumen than the first valve of the first tube, wherein the first filter is a disposable component.

7. The pressure control device according to claim 3, wherein the controller controls the opening of the second valve when the pressure reaches a first pressure.

8. The pressure control device according to claim 7, wherein the controller controls the opening of the second valve based on a change in the pressure after the second valve is controlled to open.

9. The pressure control device according to claim 8, wherein the controller controls the opening of the first valve when a rate of pressure drop after the second valve is controlled to open is less than a first rate.

10. The pressure control device according to claim 3, wherein each of the first tube and the second tube communicates with a respective pipeline passing through an insertion portion of an endoscope.

11. The pressure control device according to claim 2, wherein the lumen is the stomach.

12. An endoscope having an air and water supply tube and a forceps channel through which an insertion portion is inserted, the insertion portion being inserted into a lumen of a subject; a first tube connected to communicate with the forceps channel; a pressure sensor disposed in the first tube for measuring the pressure of a gas; a first valve disposed in the first tube for opening the gas to the atmosphere; a second tube for supplying the gas from a gas supply source to the lumen via the air and water supply tube; a second valve disposed in the second tube for opening the gas to the atmosphere; and a controller for performing opening control of at least one of the first valve and the second valve when the pressure reaches a first pressure. A pressure control system characterized by comprising the same.

13. The pressure control system according to claim 12, wherein the controller performs opening control of the second valve when a pressure drop rate after opening control of the first valve is less than a first rate.

14. The pressure control system according to claim 12, further comprising a first filter at a position closer to the lumen than the first valve in the first tube, the first filter being a disposable component.

15. The pressure control system according to claim 13, wherein the lumen is the stomach.

16. A first tube is connected to the forceps channel of an endoscope having an air and water supply tube and a forceps channel through which an insertion portion is inserted, a second tube is connected to the air and water supply tube, the insertion portion of the endoscope is inserted into a lumen of a subject, gas from a gas supply source is supplied to the lumen via the second tube and the air and water supply tube, the pressure of the gas is measured using a pressure sensor disposed in the first tube, and when the pressure reaches a first pressure, opening control is performed on at least one of a first valve disposed in the first tube and a second valve disposed in the second tube to open the gas in the lumen to the atmosphere. A pressure control method characterized by the above.

17. The pressure control method according to claim 16, wherein the second valve is opened when the pressure drop rate after opening the first valve is less than a first rate.

18. The pressure control method according to claim 16, further comprising a first filter disposed at a position closer to the lumen than the first valve of the first tube, wherein the first filter is a disposable component.

19. The pressure control method according to claim 16, wherein the lumen is the stomach.

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