Adjustable constant pressure switch and drainage system

Abstract

The adjustable constant pressure switch and drainage system comprises a shell and a pressure adjusting assembly, an input cavity and an output cavity are formed in the shell, the input cavity and the output cavity are communicated through a connecting port, and an input port and an output port are formed in the shell; the pressure adjusting assembly comprises an adjusting knob, a first spring and a partition plate, the first spring can act on the inner end of the adjusting knob and the partition plate, the adjusting knob is arranged on the shell, the partition plate and the connecting port are oppositely arranged, and the adjusting knob adjusts control pressure applied to the partition plate by adjusting the stretching amount of the first spring. The partition plate is subjected to input pressure generated by the input cavity, the input pressure and the control pressure act on the partition plate in opposite directions, and the resultant force direction of the input pressure and the control pressure determines the moving direction of the partition plate relative to the connecting port so as to open or close the connecting port. According to the scheme, the pressure regulating assembly is arranged to flexibly meet the requirements of different users, automatic opening and closing are achieved, and normal urination and use safety are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to an adjustable constant pressure switch and a drainage system. Background Art

[0002] At present, urethral drainage devices usually use cannulas to be inserted into the bladder for drainage. When drainage is required for a long time, a drainage bag is connected to the outer end of the cannula to store liquid, and a clamping device is installed on the cannula to block it. The existing clamping device is usually a clip or a Robert clip. This clamping device only has a simple switching function and requires manual control of the switch, which makes it easy to forget to turn it on or off due to human negligence. When the clamping device is forgotten to be opened, the entire drainage system will stagnate, making it impossible for the user to urinate, which will cause the user's bladder to be overfilled, which will seriously damage the kidney function and cause medical accidents; when the clamping device is forgotten to be closed, the entire drainage system will remain unobstructed, the user will not be able to store urine normally, and the bladder will continue to be empty. In the long run, it will lead to the disappearance of normal bladder tension, detrusor weakness, weakened or disappeared reflex function, and normal urination function will no longer be possible.

[0003] Therefore, how to control the drainage system for draining urine to cooperate with the urination function of the bladder, and not damage the normal function of the bladder while helping the bladder to urinate reasonably is a problem that needs to be solved urgently. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide an adjustable constant pressure switch and drainage system.

[0005] The purpose of the present invention is achieved through the following technical solutions: An adjustable constant pressure switch comprises a shell and a pressure regulating assembly, wherein an input chamber and an output chamber are arranged in the shell, the input chamber and the output chamber are connected via a connecting port, and an input port connected to the input chamber and an output port connected to the output chamber are arranged on the shell; the pressure regulating assembly comprises an adjusting knob, a first spring and a partition plate, the first spring can act on the inner end of the adjusting knob and the partition plate, the adjusting knob is arranged on the shell between the input port and the output port, the partition plate is arranged opposite to the connecting port, the adjusting knob adjusts the control pressure applied to the partition plate by adjusting the expansion and contraction amount of the first spring, the partition plate will be subjected to the input pressure generated when the input chamber drains the liquid, the input pressure and the control pressure act on the partition plate in opposite directions, the direction of the combined pressure between the two determines the moving direction of the partition plate relative to the connecting port, the connecting port is opened when the partition plate is away from the connecting port, and the connecting port is closed when the partition plate is against the connecting port.

[0006] Preferably, the pressure regulating assembly also includes a second spring, which is coaxially opposed to the first spring and respectively located on both sides of the partition plate, and the two ends of the second spring respectively abut against the inner wall of the shell and the partition plate to apply an elastic force to the partition plate in the opposite direction to the elastic force of the first spring, and the control pressure is the combined force of the elastic force of the second spring and the elastic force of the first spring.

[0007] Preferably, the pressure regulating assembly also includes a second spring, the adjusting knob can be inserted into the output cavity, the first spring and the partition plate are both located in the output cavity, the second spring is located in the input cavity, the adjusting knob increases the control pressure by compressing the first spring, and the adjusting knob reduces the control pressure by relaxing the first spring.

[0008] Preferably, the shell is formed by a main body provided with an input port and an output port and surrounded by front and rear covers, and a partition separating the input cavity and the output cavity is provided in the shell, and the connection port is located on the partition.

[0009] Preferably, the outer diameter of the partition plate is larger than the connection port, and a sealing ring is provided on the end surface of the partition plate or / and the connection port adjacent to the partition plate, and when the partition plate is in contact with the partition plate, the sealing ring seals the connection port.

[0010] Preferably, a screw hole threadedly connected to the adjusting knob is provided on the shell, and an axially retractable sealing sleeve is fixedly connected to the inner end of the screw hole, and the inner end of the adjusting knob and the end of the first spring are respectively abutted against the two side end surfaces of the sealing sleeve; or the inner end surface of the screw hole is provided with a second sealing ring tightly fitting with the inner end surface of the adjusting knob to seal the screw hole; and a limiting groove for the end of the first spring is provided on the inner end surface of the sealing sleeve.

[0011] Preferably, the voltage regulating assembly also includes a second spring, a limiting groove for the end of the first spring is provided on the inner end face of the adjusting knob, and the partition plates respectively have first limiting protrusions abutting or clamping with the end of the first spring; a limiting block abutting or clamping with the end of the second spring is provided on the inner wall of the shell, and the other side of the partition plate has a second limiting protrusion abutting or clamping with the end of the second spring.

[0012] Preferably, the adjusting knob has an adjusting end, the adjusting end is exposed from the shell, and the shell is provided with a group of indicator marks distributed along the rotation trajectory of the adjusting end, and the adjusting end can set the control pressure of the adjusting knob and / or display the opening and closing status of the connection port corresponding to the indicator marks.

[0013] Preferably, the input port is arranged at the top of the shell, and the output port is arranged at the bottom of the shell.

[0014] A drainage system comprises an input catheter, an output catheter, a drainage bag and the adjustable constant pressure switch as described above, wherein the input port of the adjustable constant pressure switch is connected to the input catheter, and the output port of the adjustable constant pressure switch is connected to the drainage bag through the output catheter.

[0015] The beneficial effects of the present invention are mainly reflected in: 1. The control pressure on the partition plate can be flexibly adjusted through the pressure regulating component. The corresponding control pressure can be flexibly preset according to the needs of different patients, and the constant pressure automatic opening and closing can be realized to help users maintain normal urination function and avoid damaging the user's bladder function. There is no need for human real-time monitoring of the control switch, freeing up hands; on the other hand, it can adapt to patients with various input pressure requirements to meet the needs of users with different physical conditions, maximize the scope of use and improve the flexibility of use; 2. A second spring is provided to form an elastic force in the opposite direction to the first spring, so that the combined force of the two forms the final control pressure. On the one hand, the second spring can ensure that the partition plate is fully opened when the first spring is away from the connection port; on the other hand, a fixed pressure supplement can be provided to the input pressure to avoid the inconvenience of adjustment caused by too low input pressure. Such a setting also makes the forces on both sides of the partition plate more balanced, which is convenient for ensuring the adjustment accuracy and stability of the adjustment knob; 3. An indicator mark is set on the shell to preset the control pressure to achieve constant pressure drainage, completely simulating the physiological urination process of the human body, maintaining the normal contraction of the patient's bladder muscles or helping the patient restore the normal contraction function of the bladder, and playing a role in bladder function training and function recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The technical solution of the present invention is further described below in conjunction with the accompanying drawings: Figure 1 : A schematic diagram of an embodiment of the present invention; Figure 2 : A partial structural diagram of an embodiment of the present invention; Figure 3 : A cross-sectional view of an embodiment of the present invention; Figure 4 : A cross-sectional view of another possible embodiment of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be described in detail below in conjunction with the specific embodiments shown in the accompanying drawings. However, these embodiments are not limited to the present invention, and any structural, methodological, or functional changes made by a person skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0018] In the description of the scheme, it should be noted that the terms "center", "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of description and simplified description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance. Moreover, in the description of the scheme, with the operator as a reference, the direction close to the operator is the proximal end, and the direction away from the operator is the distal end.

[0019] like Figures 1 to 4As shown, the present invention discloses an adjustable constant pressure switch, comprising a housing 1 and a pressure regulating assembly, wherein the housing 1 is provided with an input chamber 101 and an output chamber 102, wherein the input chamber 101 and the output chamber 102 are connected via a connecting port 105, and the housing 1 is provided with an input port 103 connected to the input chamber 101 and an output port 104 connected to the output chamber 102; the pressure regulating assembly comprises an adjusting knob 201, a first spring 202 and a partition plate 203, wherein the first spring 20 The two ends of the first spring 202 act on the inner end of the adjusting knob 201 and the partition plate 203 respectively. The inner end of the adjusting knob 201 in the present embodiment may be a recessed hole or a groove, a flat end surface or a rod-shaped extension end. The two ends of the first spring 202 preferably abut against the end surfaces of the adjusting knob 201 and the partition plate 203 vertically, and the first spring 202 may adopt any suitable form to maintain coaxial effective abutment with the adjusting knob 201 and the partition plate 203, such as abutment, abutment, or movable snap-fitting. The adjusting knob 201 is provided on the housing 1. Specifically, the adjusting knob 201 is provided on the housing 1 between the input port 103 and the output port 104. The inner end of the adjusting knob 201 can extend into the housing 1. The partition plate 203 is directly opposite to the connection port 105. The adjusting knob 201 can be rotated to adjust the expansion and contraction amount of the first spring 202, thereby adjusting the control pressure applied to the partition plate 203. When the input cavity 102 is in use, drainage fluid will flow into the input cavity 102. The input pressure generated when the drainage fluid flows into the cavity 102 is applied to the partition plate 203. The input pressure and the control pressure act on the partition plate 203 in opposite directions. The final combined force direction of the pressures between the two determines the moving direction of the partition plate 203 relative to the connection port 105 to open or close the connection port 105, that is, the connection port 105 is opened when the partition plate 203 is away from the connection port 105, and the connection port 105 is closed when the partition plate 203 is against the connection port 105.

[0020] The input cavity 101 in the present solution is connected to the bladder, so the input pressure is related to the pressure in the bladder, and the control pressure is matched with the input pressure. The control pressure is the pressure value or the related pressure value required for urination when the user's bladder is full. The pressure can be represented by liquid pressure, such as water column height (cm of water column). Since the pressure values ​​for urination of the bladder are different for different users and in different usage states, the present solution flexibly adjusts the control pressure on the partition plate 203 by presetting the required pressure value through the pressure regulating component, so as to realize constant pressure self-starting drainage, to help the user maintain normal urination function, and avoid damage to the user's bladder and kidney function, and there is no need for human real-time monitoring of the control switch, thus freeing up the hands; on the other hand, it can adapt to patients with various input pressures to meet the needs of users with different physical conditions, and maximize the scope of use and improve the flexibility of use.

[0021] Furthermore, the pressure regulating assembly further comprises a second spring 204, the second spring 204 and the first spring 202 are coaxially opposite and respectively located on both sides of the partition plate 203, the two ends of the second spring 204 are respectively in contact with the inner wall of the housing 1 and the axis of the partition plate 203, so as to apply an elastic force in the opposite direction to the elastic force of the first spring 202 to the partition plate 203, and the control pressure is the combined force of the elastic force of the second spring 204 and the elastic force of the first spring 202. The second spring 204 is arranged to form an elastic force in the opposite direction to the first spring 202, so that the combined force of the two forms the final control pressure. On the one hand, the second spring 204 can provide a fixed pressure supplement to the input pressure, avoiding the inconvenience of adjustment caused by too low input pressure, such as failure to fully open; on the other hand, such an arrangement also makes the forces on both sides of the partition plate 203 more balanced, so as to ensure the adjustment accuracy and stability of the adjustment knob 201. In order to ensure safe use, the input pressure value corresponding to the maximum value of the control pressure in this solution is a safety threshold value under the associated bladder filling state, so as to ensure that even when the control pressure reaches the maximum, urination can be performed to relieve pressure when the bladder is filled to its safety threshold value, avoiding the situation where the bladder cannot urinate due to excessive control pressure, thereby ensuring the safety of the user.

[0022] Preferably, the adjusting knob 201 may also be inserted into the output cavity 102, the first spring 202 and the partition plate 203 are both located in the output cavity 102, the second spring 204 is located in the input cavity 101, the adjusting knob 201 increases the control pressure by compressing the first spring 202, and the adjusting knob 201 reduces the control pressure by relaxing the first spring 202. The specific models and specifications of the first spring 202 and the second spring 204 are selected according to the elastic force range to be applied.

[0023] In other feasible embodiments, the positions of the first spring 202 and the second spring 204 can be swapped, and the adjusting knob 201 pulls the first spring 202 by reverse rotation to increase the control pressure, that is, the adjusting knob 201 is inserted into the input cavity 101, the first spring 202 is located in the input cavity 101, the partition plate 203 and the second spring 204 are both located in the output cavity 102, the adjusting knob 201 reduces the control pressure by compressing the first spring 202, and the adjusting knob 201 increases the control pressure by loosening the first spring 202.

[0024] like Figure 3 As shown, in the illustrated embodiment, the input port 103 is arranged at the top of the shell 1, and the output port 104 is coaxially arranged at the bottom of the shell 1. The input chamber 101 and the output chamber 102 are arranged relative to each other front to back to meet the conventional gravity direction and match the setting position of the input port 103 and the output port 104. In other feasible embodiments, the input chamber 101 and the output chamber 102 can also be arranged relative to each other up and down or diagonally at an inclined angle. Preferably, the shell 1 is in the shape of a water drop to facilitate smooth discharge. In other feasible embodiments, the shell 1 can also be other suitable shapes, which are not limited here.

[0025] The housing 1 of the adjustable constant pressure switch is formed by a main body including an input port 103 and an output port 104 and a front and rear cover plate. A partition 106 is provided between the input cavity 101 and the output cavity 102 to separate the two. The connection port 105 is located on the partition 106. The adjustable constant pressure switch is provided with a guide device for moving the partition plate 203. Specifically, the guide device can be a guide groove 107 fixedly arranged on the axis around the partition plate 106. The port of the guide groove 107 protrudes outward from the partition plate 106. The inner contour of the guide groove 107 is matched with the outer contour of the partition plate 203. The partition plate 203 is arranged in the guide groove 107 and moves along the groove wall of the guide groove 107. The guide device can ensure the movement stability of the partition plate 203. In another feasible embodiment, as Figure 4 As shown, guide posts 208 are respectively provided at the axial center areas on both sides of the partition plate 203, and the two guide posts 208 are respectively placed in the first guide groove 1011 in the input cavity 101 and the second guide groove 2011 at the inner end of the adjusting knob 201. Further, the outer diameter of the partition plate 203 is larger than the connection port 105, and a sealing ring 205 adapted to the connection port 105 is bonded or embedded on the end surface adjacent to the partition plate 203 or / and the connection port 105. When the partition plate 203 is in contact with the partition plate 106, the sealing ring 205 seals the connection port 105.

[0026] The housing 1 is provided with a screw hole 108 which is threadedly connected to the inner end of the adjusting knob 201. In order to ensure the sealing between the adjusting knob 201 and the housing 1, in a preferred embodiment, an axially retractable sealing sleeve 109 is fixedly connected to the inner end of the screw hole 108 to seal the screw hole 108. The inner end of the adjusting knob 201 and the end of the first spring 202 are respectively in contact with the two side end surfaces of the sealing sleeve 109. The sealing sleeve 109 is an axially retractable elastic sealing sleeve, which seals the screw hole 108 to ensure the sealing of the screw hole 108 while not hindering the axial adjustment of the first spring 202 by the adjusting screw 201. In another feasible embodiment, the screw hole 108 can also be embedded with a second sealing ring on its inner end surface which is tightly fitted with the inner end surface of the adjusting knob 201 to seal the screw hole 108.

[0027] In order to ensure the stability of the setting of the first spring 202, a limiting groove 110 is provided on the inner end surface of the sealing sleeve 109 or the inner end of the adjusting knob 201, which can limit or embed the end of the first spring 202, and the center of the end surface of the partition plate 203 has a first limiting convex portion 206 that is engaged or limited with the end of the first spring 202. Further, a limiting block 111 is provided on the inner wall of the housing 1 to be engaged or abutted with the end of the second spring 204, and a second limiting convex portion 207 is provided at the center of the other end surface of the partition plate 203 to be engaged or limited with the end of the second spring 204. In this solution, the end limiting structure of the first spring 202 and the second spring 204 is not limited to the illustrated embodiment, and the limiting groove 110, the first limiting convex portion 206, the limiting block 111 and other structures can be substituted for each other to form an alternative solution, and the specific adjustment and selection are made according to actual production needs.

[0028] like Figure 1-Figure 3As shown, the adjusting knob 201 has an adjusting end, and the adjusting end is exposed to the housing 1. The housing 1 is provided with a group of indicator marks distributed along the rotation trajectory of the adjusting end, and the adjusting end presets the control pressure and / or displays the opening and closing state of the connection port 105 through the indicator marks. One group of the indicator marks includes but is not limited to an "open" mark, a "closed" mark, a "zero point" mark, and a graduation value representing the control pressure value. The "open" mark and the "closed" mark correspond to the rotation starting point and the rotation end point of the adjusting knob 201, or the starting point area and the end point area, respectively, that is, the limit position or area of ​​clockwise rotation and the limit position or area of ​​counterclockwise rotation relative to the housing 1, wherein the "open" mark corresponds to the state when the control pressure is minimum and the connection port 105 is just opened; the "closed" mark corresponds to the state when the control pressure reaches the maximum or the maximum interval and the connection port 105 is closed.

[0029] The "zero point" mark is the corresponding position when the input pressure is zero and the connection port 105 is just opened or closed. A set of graduation values ​​representing the control pressure value is distributed between the "zero point" mark and the "closed" mark to identify the automatic discharge conditions under different input pressures.

[0030] An indicator mark is set on the housing 1, and the adjustment knob 201 is rotated to the state condition of the adjustable constant pressure switch preset by the indicator mark to facilitate the user's operation and ensure the accuracy of the adjustment. The structure of the adjustment knob 201 has a variety of feasible embodiments. In the illustrated embodiment, the adjustment knob 201 is a T-shaped structure, and its head is an indicator rod perpendicular to its rod, and its end forms an arrow shape for indication. In other feasible embodiments, the adjustment knob 201 can be any T-shaped structure that is easy to rotate, and the head can be any structure that is easy to twist, such as round, spherical, triangular, etc., and the outer wall of the head can also be provided with anti-slip patterns to increase friction. The head may not be provided with a tip, and may also be provided with lines or marking points for indication.

[0031] Furthermore, the present invention also discloses a drainage system, including an input catheter, an output catheter, a drainage bag and the adjustable constant pressure switch as described above, wherein the input port 103 of the adjustable constant pressure switch is connected to the input catheter, and the input catheter is used to connect to the bladder; the output port 104 of the adjustable constant pressure switch is connected to the drainage bag through the output catheter to introduce urine into the drainage bag for storage.

[0032] It should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0033] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. Adjustable constant pressure switch, characterized by: Comprising a housing (1) and a pressure regulating assembly, wherein an input chamber (101) and an output chamber (102) are provided in the housing (1), the input chamber (101) and the output chamber (102) are connected via a connecting port (105), and the housing (1) is provided with an input port (103) connected to the input chamber (101) and an output port (104) connected to the output chamber (102); The pressure regulating assembly comprises an adjusting knob (201), a first spring (202) and a partition plate (203); the first spring (202) can act on the inner end of the adjusting knob (201) and the partition plate (203); the adjusting knob (201) is arranged on the housing (1) between the input port (103) and the output port (104); the partition plate (203) is arranged opposite to the connection port (105); the adjusting knob (201) adjusts the expansion and contraction amount of the first spring (202) to thereby adjust the pressure on the partition plate (105); The partition plate (203) is subjected to the input pressure generated when the input chamber (102) drains the liquid. The input pressure and the control pressure act on the partition plate (203) in opposite directions. The direction of the combined pressure between the two determines the moving direction of the partition plate (203) relative to the connection port (105). When the partition plate (203) moves away from the connection port (105), the connection port (105) is opened. When the partition plate (203) abuts against the connection port (105), the connection port (105) is closed.

2. The adjustable constant pressure switch according to claim 1, characterized in that: The pressure regulating assembly further comprises a second spring (204), wherein the second spring (204) and the first spring (202) are coaxially opposed and respectively located on two sides of the partition plate (203), and the two ends of the second spring (204) respectively abut against the inner wall of the shell (1) and the partition plate (203) so as to apply an elastic force opposite to the elastic force of the first spring (202) to the partition plate (203), and the control pressure is the combined force of the elastic force of the second spring (204) and the elastic force of the first spring (202).

3. The adjustable constant pressure switch according to claim 1, characterized in that: The pressure regulating assembly further comprises a second spring (204); the regulating knob (201) can be inserted into the output chamber (102); the first spring (202) and the partition plate (203) are both located in the output chamber (102); the second spring (204) is located in the input chamber (101); the regulating knob (201) increases the control pressure by compressing the first spring (202); and the regulating knob (201) reduces the control pressure by relaxing the first spring (202).

4. The adjustable constant pressure switch according to claim 1, characterized in that: The housing (1) is formed by a main body provided with an input port (103) and an output port (104), and a front and rear cover plate. The housing (1) has a partition plate (106) for separating the input chamber (101) and the output chamber (102). The connection port (105) is located on the partition plate (106).

5. The adjustable constant pressure switch according to claim 1, characterized in that: The outer diameter of the partition plate (203) is greater than the connection port (105), and a sealing ring (205) is provided on an end surface adjacent to the partition plate (203) or / and the connection port (105); when the partition plate (203) is in contact with the partition plate (106), the sealing ring (205) seals the connection port (105).

6. The adjustable constant pressure switch according to claim 1, characterized in that: The housing (1) is provided with a screw hole (108) threadedly connected to the adjusting knob (201); an axially retractable sealing sleeve (109) is fixedly connected to the inner end of the screw hole (108); the inner end of the adjusting knob (201) and the end of the first spring (202) are respectively in contact with the end surfaces of both sides of the sealing sleeve (109); or the inner end surface of the screw hole (108) is provided with a second sealing ring tightly fitted with the inner end surface of the adjusting knob (201) to seal the screw hole (108); and a limiting groove (110) for the end of the first spring (202) is provided on the inner end surface of the sealing sleeve (109).

7. The adjustable constant pressure switch according to claim 1, characterized in that: The voltage regulating assembly further comprises a second spring (204); a limiting groove (110) for the end of the first spring (202) is arranged on the inner end surface of the regulating knob (201); the partition plate (203) comprises a first limiting protrusion (206) abutting or clamping with the end of the first spring (202); a limiting block (111) abutting or clamping with the end of the second spring (204) is arranged on the inner wall of the shell (1); and the other side of the partition plate (203) comprises a second limiting protrusion (207) abutting or clamping with the end of the second spring (204).

8. The adjustable constant pressure switch according to any one of claims 1 to 7, characterized in that: The adjusting knob (201) has an adjusting end, the adjusting end being exposed outside the housing (1), the housing (1) being provided with a group of indicator marks distributed along a rotation trajectory of the adjusting end, the adjusting end being able to set a control pressure of the adjusting knob (201) and / or display an open or closed state of the connection port (105) in accordance with the indicator marks.

9. The adjustable constant pressure switch according to any one of claims 1 to 7, characterized in that: The input port (103) is arranged at the top of the shell (1), and the output port (104) is arranged at the bottom of the shell (1).

10. Drainage system, characterized in that: It comprises an input catheter, an output catheter, a drainage bag and an adjustable constant pressure switch as described in any one of claims 1 to 9, wherein the input port (103) of the adjustable constant pressure switch is connected to the input catheter, and the output port (104) of the adjustable constant pressure switch is connected to the drainage bag through the output catheter.

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