WO2010059381A1 - Mécanismes à force constante pour réguler des dispositifs de distension - Google Patents

Mécanismes à force constante pour réguler des dispositifs de distension Download PDF

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Publication number
WO2010059381A1
WO2010059381A1 PCT/US2009/062597 US2009062597W WO2010059381A1 WO 2010059381 A1 WO2010059381 A1 WO 2010059381A1 US 2009062597 W US2009062597 W US 2009062597W WO 2010059381 A1 WO2010059381 A1 WO 2010059381A1
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WO
WIPO (PCT)
Prior art keywords
fluid
pressure
constant force
distension
substantially constant
Prior art date
Application number
PCT/US2009/062597
Other languages
English (en)
Inventor
Thomas E. Albrecht
Jason L. Harris
Mark S. Ortiz
Original Assignee
Ethicon Endo-Surgery, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ethicon Endo-Surgery, Inc. filed Critical Ethicon Endo-Surgery, Inc.
Publication of WO2010059381A1 publication Critical patent/WO2010059381A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F5/00—Orthopaedic methods or devices for non-surgical treatment of bones or joints; Nursing devices; Anti-rape devices
    • A61F5/0003—Apparatus for the treatment of obesity; Anti-eating devices
    • A61F5/0013—Implantable devices or invasive measures
    • A61F5/0036—Intragastrical devices
    • A61F5/004—Intragastrical devices remotely adjustable
    • A61F5/0043—Intragastrical devices remotely adjustable using injection ports

Definitions

  • the present invention relates to methods and devices for forming a distension in a lumen, and in particular to constant force mechanisms and methods for controlling fluid pressure in a distension system.
  • Obesity is becoming a growing concern, particularly in the United States, as the number of obese people continues to increase, and more is learned about the negative health effects of obesity.
  • Morbid obesity in which a person is 100 pounds or more over ideal body weight, in particular poses significant risks for severe health problems. Accordingly, a great deal of attention is being focused on treating obese patients.
  • One method of treating morbid obesity has been to place a distension device, such as an elongated gastric coil, within at least a portion of the stomach.
  • Gastric coils have typically comprised one or more rigid or flexible metallic or plastic links which may contain one or more fluid-filled elastomeric balloons with controlled endpoints that are disposed inside the stomach.
  • This gastric coil is intended to form a distension and a reduced capacity or volume in the stomach by taking a three dimensional volume and urging it towards a two dimensional shape that is likely planar in nature.
  • the gastric coil expands against the stomach creating a food intake distension in the stomach.
  • fluid is removed from the gastric coil.
  • An effect of the gastric coil is to alter feelings of satiation and satiety.
  • positive impacts on satiation and satiety may be achieved by an intra-gastric coil through one or more of the following mechanisms: reduction of stomach capacity, rapid engagement of stretch receptors, alterations in gastric motility, pressure induced alteration in gut hormone levels, and alterations to the flow of food either into or out of the stomach.
  • gastric distension devices With each of the above-described gastric distension devices, safe, effective treatment requires that the device be regularly monitored and adjusted to vary the degree of distension applied to the stomach.
  • the gastric coil may substantially increase in size following the initial implantation.
  • adjustable implantable distension devices e.g., satiation and satiety inducing gastric implants
  • optimal design features, as well as methods for installing and removing them are described in commonly owned and pending U.S. Patent Application Serial No.
  • a physician places a hand-held portion of the programmer near the gastric implant and transmits power and command signals to the implant.
  • the implant in turn adjusts the fluid levels in the gastric coil and transmits a response command to the programmer.
  • Conventional hydraulic gastric coil devices may exert a continuous restricting force on the stomach to reduce the capacity of the stomach and to trigger stretch receptors in the stomach.
  • side effects and complications of conventional gastric coil devices may include erosion of the interior stomach tissue resulting from the constant pressure of the gastric coil on the interior wall of the stomach.
  • hydraulic gastric coils do not offer stable pressure over time.
  • Hydraulic gastric coils therefore cannot guarantee the optimal configuration of the gastric coil over time. Multiple adjustments to maintain the optimal configuration of the gastric coil are required, increasing the cost and the number of medical visits. Also, adjustment of the gastric coil requires an endoscopic procedure, resulting in discomfort for the patient.
  • FIG. IA is a schematic diagram illustrating one exemplary embodiment of a distension system having a pressure adjustment unit for controlling fluid flow through the system;
  • FIG. IB is a schematic diagram illustrating another embodiment of a distension system having a pressure adjustment unit for controlling fluid flow through the system;
  • FIG. 1C is an illustration of the gastric distension system of FIG. IA implanted to form a distension in a patient's stomach;
  • FIG. ID is a cross sectional view of a gastric distension device and port of the gastric distension system of FIG. IA;
  • FIG. 2A is a perspective, partially transparent view of one exemplary embodiment of a pressure adjustment unit having a constant force mechanism that includes a nitinol spring coupled to an expandable bellows;
  • FIG. 2B is a cross-sectional view of the pressure adjustment unit of FIG. 2A;
  • FIG. 2C is a graph illustrating the force as a function of length for a nitinol spring
  • FIG. 3 A is a perspective view of another embodiment of a pressure adjustment unit having a constant force mechanism that includes screw drive having a nut disposed therearound and coupled to a torsion spring;
  • FIG. 3B is a cross-sectional view of the pressure adjustment unit of FIG. 3 A taken across line B-B;
  • FIG. 3C is another cross-sectional view of the pressure adjustment unit of FIG. 3A taken across line C-C;
  • FIG. 4A is a cross-sectional view of yet another embodiment of a pressure adjustment unit having a constant force mechanism that includes a constant force spring in contact with a cam surface;
  • FIG. 4B is a cross-sectional view of one embodiment of a distension system that includes a pressure adjustment unit having the constant force mechanism of FIG. 4A incorporated therein, showing the constant force mechanism in a first position;
  • FIG. 4C is a cross-sectional view of the distension system of FIG. 4B, showing the constant force mechanism in a second position;
  • FIG. 4D is a perspective view of another embodiment of a constant force mechanism having a constant force spring in contact with a cam surface
  • FIG. 4E is a side, partially transparent view of yet another embodiment of a constant force mechanism having a constant force spring in contact with a cam surface, showing the constant force mechanism in a first position;
  • FIG. 4F is a side, partially transparent view of the constant force mechanism of FIG. 4E shown in a second position;
  • FIG. 5 is a cross-sectional view of another embodiment of a pressure adjustment unit having a constant force mechanism that includes a constant force spring coupled to a piston;
  • FIG. 6 is a cross-sectional view of yet another embodiment of a pressure adjustment unit having a constant force mechanism that includes a compression coil spring coupled to an expandable fluid bladder;
  • FIG. 7A is a cross-sectional view of a pressure adjustment unit having a constant force mechanism with a saturated fluid disposed in a chamber according to another embodiment
  • FIG. 7B is a cross-sectional view of yet another embodiment of a pressure adjustment unit having a constant force mechanism with a saturated fluid disposed in a chamber;
  • FIG. 8 is a cross-sectional view of another embodiment of a pressure adjustment unit having a constant force mechanism with a chamber under a vacuum force;
  • FIG. 9A is a perspective, partially transparent view of another embodiment of a pressure adjustment unit having a constant force mechanism that includes an osmotic pump;
  • FIG. 9B is a perspective, partially transparent view of another embodiment of an osmotic pump for use with a constant force mechanism of a pressure adjustment unit in a distension system;
  • FIG. 9C is a cross-sectional view of yet another embodiment of an osmotic pump for use in a constant force mechanism of a pressure adjustment unit in a distension system;
  • FIG. 9D is a perspective view of that osmotic pump of FIG. 9C coupled to a distension system;
  • FIG. 10 is a schematic diagram illustrating one exemplary embodiment of a set- point adjustment mechanism.
  • a self-regulating distension system includes a distension device for forming a distension in a lumen, and a pressure adjustment unit in communication with the distension device and effective to maintain a substantially constant equilibrium pressure between the distension device and the pressure adjustment unit by regulating an amount of fluid in the distension device.
  • the distension device can include a fluid bladder capable of forming a distension in a lumen.
  • an amount of distension corresponds to an amount of fluid contained in the fluid bladder.
  • the pressure adjustment unit can be designed in a variety of ways, but in one exemplary embodiment the unit includes a constant force mechanism coupled to a fluid communication chamber that is in fluid communication with a distension device.
  • the constant force mechanism is a nitinol spring.
  • the constant force mechanism can include a spring in contact with a cam surface.
  • the spring can also include a cantilever beam and the distension system can include a set- point adjustment mechanism that can include an adjustable block movably disposed along the cantilever beam to adjust an effective length of the cantilever beam. Adjusting an effective length of the cantilever beam allows a substantially constant pressure of the pressure adjustment unit to be adjusted.
  • the constant force mechanism can include a constant force spring disposed in a chamber and coupled to a piston.
  • a set-point adjustment mechanism can also be included, and in one embodiment can include an adjustable bladder coupled to the piston and configured to adjust the substantially constant pressure of the pressure adjustment unit by adjusting an amount of friction generated between the adjustable bladder and the chamber.
  • the constant force mechanism can be a compression coil spring and the fluid communication chamber can be an expandable fluid bladder that is coupled to the compression coil spring.
  • a set-point adjustment mechanism can also be included, and in one such embodiment can include an expandable bellows coupled to the compression coil spring and configured to adjust the substantially constant pressure by adjusting a length of the compression coil spring.
  • a constant force mechanism can include a chamber containing a saturated fluid therein and configured to maintain the substantially constant pressure, independent of a volume of the chamber.
  • a set-point adjustment mechanism can also be included, and in one such embodiment can be configured to adjust the substantially constant pressure by changing a composition of the saturated fluid.
  • the constant force mechanism can include a chamber under vacuum force.
  • a set-point adjustment mechanism can also be included, and in one such embodiment can be configured to adjust a substantially constant pressure by changing a pressure acting on the chamber under vacuum force.
  • the constant force mechanism can include an osmotic pump that is effective to maintain the substantially constant pressure.
  • the osmotic pump can include an actuation chamber having an osmotic fluid disposed therein and in fluid communication with the distension device and a semi-permeable membrane that separates the actuation chamber from a fluid chamber, such as the human body or a fluid- filled housing.
  • the osmotic pump can include a fluid chamber having fluid disposed therein, an actuation chamber having a piston disposed therein, and a semi-permeable membrane that separates the fluid chamber from the actuator chamber.
  • osmotic pump can include a biodegradable plug covering at least a portion of a semi-permeable membrane and configured to disintegrate over a desired period of time.
  • the distension system can include a set-point adjustment mechanism that is configured to adjust the substantially constant pressure of the pressure adjustment unit.
  • the set-point adjustment mechanism can be a constant pressure spring disposed around an expandable bladder that is inflatable to adjust the substantially constant pressure.
  • the set- point adjustment mechanism can be a lever configured to apply a force to the pressure adjustment unit, and an adjustable fulcrum coupled to the lever and movable along the lever to adjust the force applied by the lever and thereby adjust the substantially constant pressure.
  • a system for automatically adjusting a distension device generally includes a fluid reservoir, a distension device in fluid communication with the fluid reservoir and configured to form a distension in a lumen that corresponds to an amount of fluid contained within the distension device, and a constant force mechanism coupled to the fluid reservoir and configured to apply a substantially constant force to the fluid reservoir to maintain a substantially constant pressure in the distension device.
  • the constant force mechanism can have a variety of configurations.
  • the constant force mechanism can be a constant force spring disposed in a chamber and coupled to a piston.
  • the gastric distension device includes a fluid bladder for containing fluid therein.
  • the system can also include a set-point adjustment unit coupled to the constant force mechanism and adapted to change the substantially constant force applied by the constant force mechanism.
  • the set-point adjustment unit can be an expandable bladder.
  • a distension device is implanted in a patient to form a distension in a lumen such that the distension in the lumen corresponds to an amount of fluid contained within the distension device.
  • the distension device can be coupled to a pressure adjustment unit that applies a substantially constant force to fluid in the distension device to maintain a substantially constant pressure applied by the distension device to the lumen.
  • the method can further include adjusting the substantially constant force of the pressure adjustment unit using a set point adjustment mechanism.
  • a flow of fluid into the distension device can increase an amount of distension applied by the distension device to the lumen.
  • the distension device is implanted to form a distension in a patient's stomach.
  • the present invention generally provides methods and devices for regulating a distension system.
  • the methods and devices utilize a substantially constant force mechanism to maintain a substantially constant pressure of fluid in a fluid-based distension device that is implanted to form a distension in a lumen.
  • an amount of fluid in the device can correspond to an amount of distension applied to the lumen.
  • the forces acting on the distension device i.e., the tissue in contact with the device
  • the pressure in the distension device will vary, thus affecting the amount of distension applied to the lumen.
  • the pressure is maintained mechanically and non-electrically, thus eliminating the need for any electrical components that may need to be powered to operate over extended periods of time power to operate the device. Further, it can maintain a distension in a lumen without the need to detect, sense, or read a particular parameter because the pressure adjustment unit is mechanically operable to apply a substantially constant force to the fluid contained therein in response to pressure changes to achieve a substantially constant pressure.
  • FIG. IA illustrates one embodiment of a distension system 10 having a distension device 20 configured to receive fluid to form a distension in a lumen corresponding to an amount of fluid contained therein.
  • the system 10 also includes a pressure adjustment unit 30 that is in communication with the distension device 20 for maintaining a substantially constant pressure of fluid in the distension device 20.
  • the system 10 can also optionally include an injection port 70 for receiving fluid.
  • the injection port 70 can be in fluid communication with the distension device 20 and/or the pressure adjustment unit 30 for adding fluid to the distension device 20 and/or for adjusting the substantially constant force of the pressure adjustment unit.
  • FIG. IB illustrates a catheter 90' having a Y-shaped connector 91' with a first branch portion 90a' extending from one end thereof and coupled to the distension device 20', and second and third branch portions 90b', 90c' extending from the other end thereof and coupled to the port 70' and the pressure adjustment unit 30', respectively.
  • the distension system 10 can also optionally include a set point mechanism 80, 80' that is configured to adjust the substantially constant force of the pressure adjustment unit 30, 30'.
  • the system can have a variety of other configurations and can include various other components.
  • the illustrated embodiments show a port being separate but in communication with the pressure adjustment unit, in other embodiments the port and pressure adjustment unit can be located in the same chamber or the port can be part of the pressure adjustment unit.
  • the system can also optionally include sensors or other components for measuring various parameters.
  • FIG. 1C illustrates the distension system 10 of FIG. IA implanted to form a distension in a patient's stomachlOO.
  • the distension device 20 is a gastric distension gastric coil that is positioned in a patient's stomach 100, however the present invention can be used with virtually any distension device.
  • the illustrated distension device 20 is shown in more detail in FIG. ID, and as shown the distension device 20 has a generally elongate shape with a support structure 22 having first and second opposite ends 20a, 20b that can be positioned relative to each other.
  • the distension device 20 can also include a variable volume member, such as an inflatable balloon 24, that is disposed inside of rigid link members 22, that is configured to be positioned adjacent to tissue.
  • the balloon 24 can contain a variable amount of fluid that causes the balloon 24 to expand or contract against the inner walls of the link members 22 to form an adjustable distension device for controllably restricting food intake into the stomach.
  • the gastric distension device 20 can be applied in the stomach of a patient. As shown in FIG. 1C, the distension device 20 at least substantially contacts the upper portion of the stomach 100. After the distension device 20 is implanted, preferably in the deflated configuration wherein the distension device 20 contains little or no fluid, the distension device 20 can be inflated, e.g., using saline, to increase the size of the distension device.
  • various techniques including those disclosed herein, can be used to initially inflate and/or adjust the distension device 20.
  • gastric coil can have a variety of other configurations, moreover the various methods and devices disclosed herein have equally applicability to other types of distension devices.
  • the pressure adjustment unit 30, as well as any port 70 or set-point adjustment mechanism 80 coupled thereto, can also be implanted in the patient.
  • the particular location can vary as desired by the surgeon.
  • the pressure adjustment unit 30 is configured to apply a substantially constant force to a fluid communication chamber that is in fluid communication with the distension device.
  • the substantially constant force is always constant, in application constant force mechanisms attempt to achieve a constant force but are not always one hundred percent effective at maintaining that force one hundred percent of the time. Accordingly, a person skilled in the art will appreciate that the terms "constant force,” “constant pressure,” and “constant equilibrium” as used herein are intended to mean a substantially constant force, pressure, and equilibrium, and that minor variations will occur.
  • the substantially constant force remains within ten percent of the intended force.
  • the substantially constant force that is supplied can be based on a pre-set pressure, which is a desired substantially constant pressure to be maintained in the distension device 20 by the pressure adjustment unit 30 (thereby maintaining a substantially constant equilibrium between the distension device 20 and the pressure adjustment unit 30).
  • the pre-set pressure can be set prior to implantation, and preferably it is set on a patient-by-patient basis.
  • a variety of different constant force mechanisms can be incorporated into the pressure adjustment unit 30 to supply the substantially constant force.
  • a pressure of fluid in the distension device 20 decreases (for example, due to patient weight loss) or increases (for example, due to patient weight gain) to a pressure that is less than or greater than the pre-set pressure controlled by the pressure adjustment unit 30, in response the pressure adjustment unit 30 will increase or decrease an amount of fluid in the distension device 20 until the pressure of fluid in the distension device 20 is equal to the pre-set pressure. More particularly, in an instance where a size of an area being restricted, such as a coil frame of a stomach 100, decreases due to actions like weight loss, the pressure in the distension device 20 will decrease and thus the pressure in the distension device 20 needs to be increased to maintain enough pressure around the newly sized coil frame.
  • the pressure adjustment unit 30 is configured to supply a substantially constant force to a fluid communication chamber in fluid communication with the distension device 20, when the pressure in the distension device 20 drops below the pre-set pressure (as defined by the substantially constant force), the pressure adjustment unit 30 in response will cause fluid to flow from the fluid communication chamber into the distension device 20 until the pressure of fluid in the distension device 20 returns to the pre-set pressure.
  • the pressure adjustment unit 30 is continuously attempting to achieve an equilibrium between the continuously varying forces acting on the pressure adjustment unit 30 by the fluid in the system (i.e., the fluid in the fluid communication chamber and the distension device) and the substantially constant force applied to the fluid in the system by the constant force mechanism.
  • the system 10 can thus control an amount of fluid added into and/or removed from the distension device 20, thereby controlling an amount of distension that is formed by the distension device 20. More particularly, as fluid is added to the distension device 20, the amount of the distension increases, and likewise, as fluid is removed from the distension device 20, the amount of the distension decreases.
  • the pressure adjustment unit 30 requires the use of no outside energy or forces to adjust the amount of distension in a distension device 20. Further, a person skilled in the art will appreciate that compensation for pressure changes in the distension device 20 can be in real time and immediate.
  • the pressure adjustment unit 30 can be configured such that the pressure adjustment unit 30 will cause fluid to flow into the distension device 20 only when a pressure of fluid in the distension device 20 is less than the pre-set pressure. When a pressure of fluid in the distension device 20 is greater than the pre-set pressure, the pressure adjustment unit 30 can take no action. This can be advantageous to allow for small variations in the pressure in the distension device 20, for example while the patient is eating, without continuously altering the fluid pressure in the distension device 20. An additional benefit associated with this approach is that some patients may never actually require fluid removal from the distension device, and instead require only incremental fluid transfer into the distension device.
  • FIGS. 2A and 2B One exemplary embodiment of a pressure adjustment unit 130 is illustrated in FIGS. 2A and 2B.
  • the pressure adjustment unit 130 generally includes a housing 132 having proximal 132p and distal ends 132d with an access port 134 formed in the distal end 132d thereof.
  • a constant force mechanism and a fluid communication chamber are formed and/or disposed within the housing 132.
  • the fluid communication chamber is in the form of a bellows 136
  • the constant force mechanism is in the form of a nitinol spring 140 that applies a constant force to a transfer mechanism, such as a piston 138, that acts on fluid in the bellows 136.
  • the bellows 136 is disposed in the distal end 132d of the housing 132 and it can include an open distal end that is in fluid communication with the access port 134, which can be coupled to a distension device.
  • a proximal end of the bellows 136 can be coupled to the piston 138, which is located proximal to the bellows 136 within the housing 132.
  • the piston 138 can be slidable in the housing 132 and configured to act on a proximal end of the bellows 136 to push fluid from inside the bellows 136 out through the access port 134.
  • the constant force mechanism can be located proximal to the piston 138 and it can configured to apply a substantially constant force to the piston 138.
  • the nitinol spring 140 is effective to provide a substantially constant force because of the properties of nitinol.
  • nitinol springs typically include a constant stress zone such that as a length of the spring changes, the force applied by the spring remains constant, until a particular length is reached at either end of the stress zone, at which point the force of the spring again changes.
  • the nitinol spring 140 can be capable of distending a significant amount while still applying approximately the same force to the piston 138.
  • FIGS. 2A and 2B shows the bellows 136, piston 138, and nitinol spring 140 as separate components, in other embodiments these components can be selectively combined or removed provided that the pressure adjustment unit 130 is still configured to maintain a substantially constant pressure in the distension device.
  • the piston 138 can be eliminated and the constant force mechanism can act directly on the bellows 136.
  • the nitinol spring 140 can be incorporated into the bellows 136 to form a single component operable to provide a substantially constant force.
  • other similar components can be substituted for some of the illustrated components.
  • the bellows 136 can be replaced by other components that are expandable and/or retractable and can be in fluid communication with the access port 134.
  • other constant force mechanisms some of which are described herein, can be substituted for the nitinol spring 140 and adapted for use in the pressure adjustment unit 130.
  • the nitinol spring 140 defines the pre-set pressure, which is a desired substantially constant pressure to be maintained in the distension device by the pressure adjustment unit 130.
  • the nitinol spring 140 expands to push the piston 138 distally toward the bellows 136 because the substantially constant force supplied by the nitinol spring 140 exceeds the decreased pressure of the fluid in the distension device. Actuation of the piston 138 distally will cause the bellows 136 to be pushed distally, forcing fluid in the bellows 136 to exit through the access port 134 and to be delivered to the distension device to raise the pressure of the fluid disposed therein.
  • FIGS. 2A-2B also illustrate a mechanism for adjusting the pre-set pressure, which will be discussed in more detail below.
  • FIGS. 3A- 3C Another embodiment of a pressure adjustment unit 230 is illustrated in FIGS. 3A- 3C.
  • the pressure adjustment unit 230 includes a housing 232 having proximal and distal ends 232p, 232d with an access port 234 formed in the distal end 232d thereof and a constant force mechanism 240 disposed therein.
  • the housing 232 includes a fluid communication chamber or reservoir 242 formed a distal portion thereof and in fluid communication with a distension device via the port 234.
  • the constant force mechanism 240 includes a screw 244 that extends axially through the housing 232 and that includes a piston 245 coupled to a distal end thereof and configured to apply a force to the reservoir 242.
  • the screw 244 has an inclined plane 246, such as a thread, formed therearound, and a nut 248 is threadably disposed around a mid or proximal portion of the screw 244.
  • the nut 248 is rotatable within the housing 232, but is fixed axially.
  • a torsion spring 250 is disposed around and coupled to the nut 248 such that the torsion spring 250 is configured to apply a force that rotates the nut 248 in a desired direction, thereby causing the screw 244 to move axially within the housing 232. Movement of the screw 244 axially within the housing 232 is effective to move the piston 245 axially within the housing 232, thereby increasing or decreasing a force applied to the fluid in the fluid reservoir 242.
  • the torsion spring 250 is configured to apply a substantially constant force that turns the nut 248 in a clockwise direction which thereby applies a distally-directed force to the inclined plane 246.
  • the torsion spring 250 defines the pre-set pressure.
  • the torsion spring 250 causes the nut 248 to rotate in the clockwise direction, which in turn moves the screw 244 and piston 245 distally. Distal movement of the piston 245 pushes against the reservoir 242, thereby pushing the fluid out of the reservoir 242, through the access port 234, and into the distension device to raise the pressure of the fluid disposed therein.
  • the pressure of the fluid in the distension device reaches the pre-set pressure, an equilibrium state is achieved and no further pressure is applied to the fluid in the reservoir 242 and the distension device.
  • fluid can flow from the distension device, through the access port 234, and into the reservoir 242.
  • Flow of the fluid into the reservoir 242 can cause the piston 245 to move in the proximal direction, which in turn can move the screw 244 proximally causing the nut 248 to rotate in an opposite direction, releasing tension applied to the torsion spring 250 by the nut.
  • the piston 245 and screw 244 will continue to move proximally until the force applied to the piston 245 and screw 244 by the pressure of fluid in the distension device is equal to the force applied to the screw 244 and piston 245 by the torsion spring 250 acting on the nut 248.
  • FIG. 3A further illustrates a port 270 that is coupled to the pressure adjustment unit 230 for adjusting the substantially constant force of the constant force mechanism, as will be discussed in more detail below.
  • FIG. 4A illustrates another exemplary embodiment of a constant force mechanism 340 for use in a pressure adjustment unit.
  • the constant force mechanism 340 includes a block 344 slidably disposed on a sliding surface 346.
  • the block 344 includes multiple rollers 354 located on a bottom surface of the block 344 and adapted to slide along the sliding surface 346.
  • the block 344 can have various other configurations that allow the block 344 to slide along the sliding surface 346.
  • the block 344 has a cam surface 348 formed thereon, and a spring 350 is in contact with the cam surface 348 of the block 344.
  • the cam surface 348 is substantially straight, in another embodiment the cam surface 348 can be sloped or curved.
  • the spring 350 can have various configurations, but in an exemplary embodiment it is configured to apply a downward force Fs to the cam surface 348.
  • a normal force F N1 can be configured to maintain the horizontal position of the downward force Fs, for example by applying a linear slide or other normal force-supplying object to the spring 350.
  • the forces applied by the spring 350 to the cam surface 348 result in a substantially constant force F being applied to the block 344, as illustrated along the x-axis.
  • a constant force mechanism like the constant force mechanism 340 illustrated in FIG. 4A can easily be incorporated into a distension system 310', as illustrated in FIGS. 4B and 4C.
  • the constant force mechanism 340' has a block 344' that slidably disposed on a sliding surface 346'.
  • the block 344' has a cam surface 348' formed thereon and a cantilevered beam 352' is in contact with the cam surface 348' of the block 344'.
  • the cantilevered beam 352' can include a bearing element 350' formed on a terminal end thereof and configured to bear against the cam surface 348' to allow movement of the cantilevered beam 352' along the cam surface 348'.
  • the block 344' is configured to slide along the sliding surface 346' without the aid of rollers, although rollers or other similar sliding devices could also be used. Movement of the block 344' can occur in response to the substantially constant force F' applied to the block 344' and in response to a force Fp' applied to the block 344' by a fluid in fluid communication with a distension device. While various techniques can be used to allow fluid communication between the constant force mechanism 340' and a distension device, in the illustrated embodiment the system 310' includes a fluid communication chamber, such as a fluid reservoir 370' formed in a housing 371' and in fluid communication with a distension device 320'. A piston 372' is coupled to the block 344' and is disposed within the fluid reservoir 370'. The piston 372' is configured to slidably move within the reservoir as the block 344' slidably moves along the sliding surface 3436'.
  • a fluid communication chamber such as a fluid reservoir 370' formed in a housing 371' and in fluid communication with
  • the cantilevered beam 352' defines the substantially constant pressure, which corresponds to the desired pre-set pressure.
  • the substantially constant force F' applied to the block 344' by the cantilevered beam 352' will exceed the force F F ' applied to the block 344' (via the piston 372') by the fluid, and thus the beam 352' will cause the block 344' to move to the right as illustrated in FIG. 4C. Movement of the block 344' to the right causes the piston 372' attached thereto to also move to the right, which in turn pushes fluid from the reservoir 370' and into the distension device 320' to raise the pressure of the fluid disposed therein.
  • FIGS. 4B- 4D also illustrate a mechanism for adjusting the pre-set pressure, which will be discussed in more detail below.
  • FIGS. 4E and 4F Another embodiment of a constant force mechanism 340" having a spring 350" in contact with a cam surface 348" is illustrated in FIGS. 4E and 4F.
  • the constant force mechanism 340" has an adjustable cantilever device 344" slidably coupled to a sliding surface 346".
  • the adjustable cantilever device 344" includes a cantilever beam 345" having a cam surface 348" formed thereon.
  • the cantilevered beam 345" can be fixedly, but optionally adjustably, coupled to a base 345b".
  • the adjustable cantilever device 344' can also include a spring 350" that is configured to apply a force to the cantilevered beam 345" to cause the beam 345" (with the base 345b” coupled thereto) to move in the right and left directions.
  • the spring 350" is extended along an arm 346a" that extends transverse to the beam 345".
  • the spring 350" includes a first end that is fixedly coupled to a base 346b" of the arm 346a” and a second end that is mated to a bearing element 352".
  • the bearing element 352" is movably mounted along a length of the arm 346a” and is slidably seated on the cam surface 348" of the beam 345". In use, the spring 350" applies a force to the beam 345" via the bearing element 352".
  • This force can cause the beam 345 and the base 346b" mated to the beam 345" to slide along a sliding surface 346" on a base 346b” mated to the arm 346'a", as shown in FIGS. 4E and 4F.
  • the bearing element 352" will move up and down relative to the arm 346a" due to the angled cam surface 348" and the force of the spring 350" acting on the bearing element 352".
  • the normal forces acting on the beam 345" by the adjustable cantilever device 344" will result in a substantially constant force F".
  • This substantially constant force F" can supply a substantially constant pressure, i.e., the pre-set pressure, to fluid in a distension system.
  • a substantially constant pressure i.e., the pre-set pressure
  • the embodiment of the constant force mechanism 340" illustrated in FIGS. 4E and 4F can easily be incorporated into a variety of distension systems, such as the distension system 310' illustrated in FIGS. 4B and 4C, in much the same manner that the embodiment of the constant force mechanism 340 illustrated in FIG. 4A is incorporated to the distension system 310' illustrated in FIGS. 4B and 4C as described above.
  • the constant force mechanism 340" illustrated in FIGS. 4E and 4F defines the pre-set pressure, and thus operates in much the same manner as described above with respect to the constant force mechanism 340 of FIG. 4A.
  • FIG. 5 illustrates another embodiment of a pressure adjustment unit 440 having a constant force mechanism disposed therein.
  • the pressure adjustment unit 440 generally includes a chamber or housing 442 having proximal and distal ends 442p, 442d.
  • the housing 442 includes a constant force spring 446 disposed in a proximal end 442p thereof, and a piston 452 disposed distal of and coupled to the constant force spring 446.
  • a portion of the constant force spring 446 is unwound and disposed along a portion of the housing 442 with a terminal end being fixedly attached to the housing 442.
  • the housing 442 can include a slot formed therein adjacent to the unwound portion to allow the coiled portion of the constant force spring 446 to wind and unwind relative to the unwound portion. This allows the coiled portion, with the piston 452 coupled thereto, to move proximally and distally within the housing 442. Since the constant force spring 446 is biased to the coiled configuration, the spring 446 will apply a distally directed constant force to the piston 452, thereby applying a constant force to a fluid reservoir 450 located distal of the piston 452 and in fluid communication with a distension device, e.g., via a port 442p formed in the housing 442.
  • the housing 442 can also optionally include an inflatable bladder 448 disposed therein and coupled to the piston 452 for adjusting a constant force of the constant force mechanism, as will be discussed in more detail below.
  • the constant force spring 446 defines the pre-set pressure.
  • the constant force spring 446 winds to push the piston 452 distally into the fluid reservoir 450 because the substantially constant pressure exceeds the decreased pressure of the fluid in the distension device.
  • fluid is pushed from the fluid reservoir 450 through the port 442p and into to the distension device to raise the pressure of the fluid disposed therein.
  • the pressure of the fluid in the distension device reaches the substantially constant pressure, an equilibrium is achieved and no fluid flows between the fluid reservoir 450 and the distension device.
  • FIG. 6 illustrates yet another embodiment of a pressure adjustment unit having a housing 542 with proximal and distal ends 542p, 542d and an access port 544 formed in the distal end 542d thereof.
  • a first fluid bladder such as a first bellows 546, is disposed in the distal end 542d of the housing 542 and is coupled to a spring 548.
  • the spring 548 can extend between the first bellows 546 and a second bellows 550 which can be used to adjust a constant force of the spring, as will be discussed in more detail below, or alternatively the second bellows 550 can be removed and the proximal end of the spring 548 can be coupled to the proximal end of the housing 542.
  • the first bellows 546 can be in fluid communication with the access port 544, which can be in communication with a distension device.
  • the first bellows 546 can both expand and contract based on a volume of fluid disposed therein (i.e., in responses to pressure changes in the distension device).
  • the spring 548 can have various configurations, but in an exemplary embodiment the spring 548 is a coil spring that is biased to an expanded position for applying a substantially constant force to the first bellows 546 to push fluid disposed therein from inside the first bellows 546, out of the access port 544, and into a distension device coupled thereto.
  • the spring 548 defines the pre-set pressure.
  • the force applied to the bellows 546 by the spring 548 will exceed the force applied to the bellows 546 by the fluid therein and in communication with the distension device.
  • the spring 548 will expand to compress the bellows 546. This will cause fluid disposed therein to leave the bellows 546 through the access port 544 and enter the distension device to raise the pressure of the fluid disposed therein.
  • the pressure of the fluid in the distension device reaches the pre-set pressure, an equilibrium is reached and no further expansion of the spring 548 and compression of the bellows 546 occurs.
  • the bellows 546 can expand to receive fluid from the distension device thereby decreasing the pressure of fluid in the distension device.
  • the spring 548 will continuously act on the bellows 546 in response to changes in the fluid pressure in the distension device to maintain a substantially constant pressure, i.e., the pre-set pressure, in the distension device.
  • FIGS. 7 A and 7B illustrate two other embodiments of pressure adjustment units 640, 640' having constant force mechanisms therein.
  • Each pressure adjustment unit 640, 640' generally includes a housing or chamber 642, 642' containing a saturated fluid 646, 646' and a transfer mechanism for applying force to a fluid reservoir in fluid communication, e.g., through an access port 644, 644', with a distension device.
  • the saturated fluid 646, 646' can be any number of liquids or gases, but in one exemplary embodiment, the saturated fluid 646, 646' is DuPont Dymel aerosol propellant or butane. In the embodiment illustrated in FIG.
  • the transfer mechanism is a first piston 648 disposed in the chamber 642 and coupled to a second piston 650 that is disposed in a fluid communication chamber or reservoir 670.
  • the first piston 648 moves to the right thereby moving the second piston 650 to the right to push a portion of the fluid out of the reservoir 670 and through the access port 644 to increase a pressure of fluid in the distension device.
  • the transfer mechanism is a flexible bladder 671' disposed within the chamber 642' and having a fluid reservoir 670' therein and in fluid communication with a distension device.
  • the saturated fluid 646, 646' defines the pre-set pressure.
  • the transfer mechanism pushes fluid from the reservoir 670, 670' and into the distension device to raise the pressure of the fluid disposed therein.
  • a pressure drop of the fluid in the distension device results in the substantially constant pressure displacing the first piston 648 to the right, which in turn displaces the second piston 650 disposed in the fluid reservoir 670 to the right to push the fluid from the reservoir 670 through the access port 644 and into the distension device.
  • FIG. 7 A a pressure drop of the fluid in the distension device results in the substantially constant pressure displacing the first piston 648 to the right, which in turn displaces the second piston 650 disposed in the fluid reservoir 670 to the right to push the fluid from the reservoir 670 through the access port 644 and into the distension device.
  • a pressure drop of the fluid in the distension device results in the substantially constant pressure compressing the bladder 671' disposed therein to push the fluid from the reservoir 670' through the access port 644' and into the distension device.
  • the pressure of the fluid in the distension device reaches the substantially constant pressure, an equilibrium is achieved and no fluid flows between the reservoir 670, 670' and the distension device.
  • the pressure of the fluid in the distension device rises above the pre-set pressure, fluid can flow from the distension device, through the access port 644, 644', and into the reservoir 670, 670'.
  • Flow of the fluid into the reservoir 670, 670' can cause the volume of the reservoir 670, 670' to expand, which in turn causes the volume of the chamber 642, 642' containing the saturated fluid 646, 646' to contract.
  • the pressure in the distension device can drop until it reaches the pre-set pressure, at which point no fluid flows between the reservoir 670, 670' and the distension device.
  • the constant force mechanism 740 for use in a pressure adjustment unit is illustrated in FIG. 8.
  • the constant force mechanism 740 generally includes a chamber or housing 742 with an evacuated volume 744, also referred to as a negative pressure or vacuum chamber.
  • a piston 746 is disposed at least partially in the housing 742, and a fluid communication chamber, such as a reservoir 750, is coupled to the piston 746 and is in fluid communication with a distension device, e.g., via an access port 751.
  • the housing 742 is adapted to receive a force to act on the piston 746 and thus against the evacuated volume 744.
  • the housing 742 includes an opening 748 therethrough that is effective to receive a substantially constant pressure that is independent of volume, for instance atmospheric pressure, to act on the piston 746. Since the evacuated volume is disposed beneath the piston 746, the resulting force from the atmospheric pressure is provided independent of displacement of the piston 746. Accordingly, similar to the embodiments of FIGS. 7 A and 7B that incorporate the saturated fluid 646, 646', this constant force mechanism 740 can maintain a substantially constant pressure, independent of volume, for a range of volumes. Accordingly, the resultant substantially constant pressure can be used as the pre-set pressure.
  • a substantially constant pressure that is independent of volume, for instance atmospheric pressure
  • the evacuated volume 744 defines the pre-set pressure.
  • the piston 746 is displaced in an illustrated downward direction to cause fluid in the reservoir 750 to flow through the port 751 to the distension device.
  • the pressure of the fluid in the distension device reaches the substantially constant pressure, an equilibrium is achieved and no fluid flows between the reservoir 750 and the distension device.
  • fluid can flow from the distension device and into the reservoir 750. Flow of fluid into the reservoir 750 can cause the piston 746 to be displaced in the illustrated upward direction.
  • the pressure in the distension device can drop until it reaches the pre-set pressure, at which point no fluid flows between the reservoir 750 and the distension device.
  • FIGS. 9A-9D illustrate additional embodiments of a pressure adjustment unit having a constant force mechanism disposed therein.
  • the constant force mechanism is an osmotic pump.
  • the osmotic pump 840 generally includes a housing 842 with a proximal end 842p having a semipermeable membrane 846 formed therein and a distal end 842d having an access port 844 formed therein.
  • the semi-permeable membrane 846 can be adapted to allow fluid to flow into and out of the housing 842 while sealing dissolved species in the fluid contained in the housing 842 from the outside environment.
  • the semi-permeable membrane 846 is made of cellulose acetate.
  • the housing 842 can further include an osmotic chamber 848 (sometimes referred to as an osmotic engine) having an osmotic substance, such as a salt-like solution, contained therein and in fluid communication with the semi-permeable membrane 846.
  • an osmotic chamber 848 (sometimes referred to as an osmotic engine) having an osmotic substance, such as a salt-like solution, contained therein and in fluid communication with the semi-permeable membrane 846.
  • the osmotic substance can be disposed in the osmotic chamber 848 prior to receiving any fluid through the semi-permeable membrane 846.
  • a piston 850 can be slidably disposed in the housing 842 and it can be in communication with the osmotic chamber 848 to receive a resulting substantially constant force created by osmotic pressure, which can result from a difference in concentration of dissolved species on opposite sides of the semi-permeable membrane 846, within the osmotic chamber 848. Slidable movement of the piston 850 can apply the resulting substantially constant force to a fluid 852 disposed in the housing 842, distal of the piston 850, to move the fluid 852 from the housing 842 through the access port 844 for delivery to a distension device.
  • a biodegradable plug 854 can optionally be coupled to the semi-permeable membrane 846 at the proximal end 842p for delaying fluid flow through the semipermeable membrane 846 and/or into the osmotic chamber 848.
  • the biodegradable plug can be made of a variety of materials capable of delaying the flow of fluid, but in one exemplary embodiment the plug 854 is made of polyactide or polyglycolide. Further, the size and shape of the plug 854 can vary depending on the desired delay.
  • the osmotic pump 840 can also optionally be coupled to a port 870, which in the illustrated embodiment can be used to directly add fluid to the system.
  • the location of the port 870 with respect to the osmotic pump 840 can vary, but in the illustrated embodiment the port 870 is located above the osmotic pump 840. In another embodiment, shown in FIG. 9B, the port 870' can be located substantially in-line with and proximal to the osmotic pump 840'. Likewise, other configurations between the osmotic pump and the port are possible, just as other configurations of the components of the osmotic pump are possible. For example, in embodiments that incorporate the biodegradable plug 854 the plug 854 can be disposed anywhere in the osmotic pump 840 that is effective to delay fluid flow, for example in the housing 842 near the access port 844.
  • the osmotic pressure which can be created by a difference in concentration of dissolved species on opposite sides of the semi-permeable membrane 846, within the osmotic chamber 848 of the osmotic pump 840 defines the pre-set pressure.
  • the pressure within the osmotic chamber 848 also drops, and fluid is driven across the semi-permeable membrane 846, across an osmotic potential, and into the osmotic chamber 848 to push the piston 850 distally toward the access port 844 because the substantially constant pressure supplied by the osmotic pump 840 exceeds the decreased pressure of the fluid in the distension device.
  • Actuation of the piston 850 distally can cause the fluid 852 disposed distal thereof to be pushed distally through the access port 844 and into the distension device to raise the pressure of the fluid disposed therein.
  • the pressure of the fluid in the distension device reaches the substantially constant pressure, an equilibrium state is achieved where the pressure of the distension device and the osmotic chamber 848 equals the osmotic pressure, and no fluid flows between the osmotic pump 840 and the distension device.
  • the pressure of the fluid in the distension device rises above the pre-set pressure, fluid can flow from the distension device through the access port 844 and into the distal end of the housing 842.
  • Flow of the fluid into the distal end of the housing 842 can cause the piston 850 to be pushed in the proximal direction, and fluid within the osmotic chamber 848 can be forced through the semi-permeable membrane 846 in the proximal direction.
  • the pressure in the distension device can drop until it reaches the pre-set pressure, at which point no fluid flows between the osmotic pump 840 and the distension device.
  • the fluid is water.
  • the osmotic pump 840 can be used to fill a distension device, either initially or at some later point after implantation. More particularly, after the distension device and pressure adjustment unit are implanted in a patient, fluid can flow through the semi-permeable membrane 846 and into the osmotic chamber 848 to be reacted to create a substantially constant force as described above.
  • the inclusion of the biodegradable plug 854 can be effective to delay the time it takes for fluid to pass from outside of the osmotic pump 840, through the semi-permeable membrane 846, and into the osmotic chamber 848.
  • the biodegradable plug 854 occludes such entry, but as the fluid erodes the biodegradable plug 854, 854', the fluid can slowly enter the osmotic chamber 848 and react as described above.
  • the osmotic pump 840 can operate substantially as described above.
  • the biodegradable plug 854 can be adapted to disintegrate over a four week period to gradually fill the distension device.
  • FIGS. 9C and 9D illustrate another embodiment of an osmotic pump 840".
  • the osmotic pump 840" generally includes a housing 842" with a proximal end 842p" and a distal end 842d” having an access port 844" formed therein and coupled to a distension device 820".
  • the housing 842" can include an osmotic chamber 848", but in this embodiment the osmotic chamber 848" is disposed in the distal end 842d" of the housing 842" and coupled to the access port 844".
  • a fluid chamber 856" and a semi-permeable membrane 846" can also be disposed in the housing 842".
  • a fluid lumen 858" can extend from the fluid chamber 856" to the osmotic chamber 848" with the semi-permeable membrane 846" being disposed in the fluid lumen 858" and adapted to allow only fluid to flow bi-directionally from the fluid chamber 856" to the osmotic chamber 848", thereby sealing dissolved species contained in the fluid of the osmotic chamber 848" from the fluid chamber 856".
  • Multiple gaskets 860" can be disposed on either side of the semi-permeable membrane 846" to provide further sealing between the fluid chamber 856" and the osmotic chamber 848".
  • the fluid that flows from the fluid chamber 856" through the lumen 858" and into the osmotic chamber 848” can be any number of substances adapted to flow across an osmotic potential gradient and into the osmotic chamber 848", but in one embodiment the fluid is water.
  • the fluid chamber 856" can be a human body and the fluid 852" can be water derived from a bodily fluid.
  • the semi-permeable membrane 846" is exposed to the body and adapted to receive bodily fluid into the osmotic chamber 848".
  • the housing 842" can be constructed in two parts 841", 843", with the first part 841" containing the osmotic chamber 848" and the second part 843” containing the remaining components of the osmotic pump 840". While the two parts 841", 843” can be coupled in a number of different manners, in one embodiment they are threadably connected. Further, as illustrated, by connecting the two parts 841", 843" together, a compression force can be exerted on the gaskets 860". This force can be accentuated by disposing a spring 862" therein that is effective to compress the gaskets 860" against the semi-permeable membrane 846" to allow for proper sealing of the semi-permeable membrane.
  • multiple o-rings 864" can be disposed around components such as the spring 862" and the gaskets 860" to maintain a desired location therein. Similar to the osmotic pumps 840, 840', the osmotic pump 840" can optionally be coupled to a port 870", which as described in further detail below can be used to alter the pre-set pressure and/or add fluid to a system 810".
  • the pressure adjustment units described herein are generally adapted to produce a substantially constant force, and further, can be configured to regulate an amount of fluid flow between a reservoir and a distension device based on a pre-set pressure (i.e., by maintaining a substantially constant pressure), it can be desirable to change the pre-set pressure of a pressure adjustment unit once the pressure adjustment unit has been implanted.
  • the pre-set pressure can be set prior to implantation, and preferably it is set on a patient-by-patient basis. However, as the anatomy of a patient changes, it is often the case that the original pre-set pressure is no longer the proper pre-set pressure for a particular patient.
  • the pressure adjustment unit can be removed from the patient, recalibrated, and then re-implanted into the patient. However, it is preferred that such adjustments can occur non-invasively. Accordingly, various methods and devices are also provided for adjusting the pre-set pressure, preferably with the system still implanted. In general, a set-point adjustment mechanism is provided for allowing the pre-set pressure of a pressure adjustment unit to be changed non-invasively. A variety of different set-point adjustment mechanisms are described herein. A person skilled in the art will recognize that while some of the embodiments described are primarily applicable to a particular embodiment or pressure adjustment unit, other embodiments can be applied to most pressure adjustment units. Accordingly, a particular set-point adjustment mechanism discussed with respect to a particular pressure adjustment unit can also generally be used with other pressure adjustment units.
  • a housing 182 having an expandable member 184 and a biasing mechanism disposed therein.
  • the expandable member 184 can have a variety of configurations, such as an expandable balloon or fluid bladder.
  • This biasing mechanism can also have a variety of configurations, but in the illustrated embodiment the biasing mechanism is a nitinol spring 186 axially disposed around at least a portion of the expandable member 184. As described with respect to the nitinol spring 140 of FIGS.
  • an alloy with superelastic properties such as nitinol has particular properties that make it ideal for use in a system that applies a substantially constant force over a given length of a spring.
  • the nitinol spring 186 can be tuned to a particular set- point adjustment pressure such that the set-point adjustment mechanism is operable to change the pre-set pressure of the pressure adjustment unit 130 from an initial pre-set pressure, defined by the pre-set pressure, to an adjusted pre-set pressure, defined by the combination of the pre-set pressure and the set-point adjustment pressure.
  • a septum 188 adapted to receive a needle or other fluid delivery device can be located at a proximal end 182p of the housing 182 and it can be positioned adjacent to the expandable member 184 such that a fluid delivery device passed through the septum 188 can deliver fluid into and expand the expandable member 184.
  • the septum 188 is self-sealing which can allow a needle to penetrate the septum 188 without leaving an opening in the septum 188.
  • An exit port 190 can be located at a distal end 182d of the housing 182 and it can be configured to allow fluid to flow between the expandable member 184 and the pressure adjustment unit 130.
  • the pressure adjustment unit 130 can have a variety of different mechanisms configured to receive the fluid from the set-point adjustment mechanism 180 and thereby adjust a secondary force acting on the bellows 136 created by fluid flow from the set-point adjustment mechanism 180.
  • a piston can be located on a proximal end of the nitinol spring 140, or a piston can be mated to or formed on the bellows 136.
  • the nitinol spring 186 in conjunction selectively with the secondary force acting on the bellows 136, defines the set-point adjustment pressure.
  • the set-point adjustment pressure is the pressure at which the fluid from the expandable member 184 is pushed out of the expandable member 184, through the exit port 190, and into the pressure adjustment unit 130 by the substantially constant force of the nitinol spring 186.
  • fluid can be pushed into the expandable member 184 from the pressure adjustment unit 130 to remove the secondary force acting on the bellows 136.
  • a fluid can be added to the expandable member 184 through the septum 188 to expand the expandable member 184.
  • the expandable member 184 prior to receiving fluid through the septum 188, the expandable member 184 is approximately empty and is thus in a deflated state.
  • a volume of the expandable member 184 increases and the expandable member 184 eventually contacts the nitinol spring 186 and expands it.
  • the spring 186 is made of nitinol, the force supplied by the spring 186 does not change as the spring 186 expands and thus the force remains a substantially constant force.
  • Fluid can continue to be added to the expandable member 184 until the set-point adjustment pressure is achieved, at which point the nitinol spring 186 forces the fluid from the expandable member 184, through the exit port 190, and into the pressure adjustment unit 130.
  • the secondary force acts on the bellows 136, and in conjunction with the pressure created by the nitinol spring 140, creates the adjusted pre-set pressure.
  • the addition of the fluid into the pressure adjustment unit 130 can change the pre-set pressure from the initial pre-set pressure, i.e. the pressure created by just the nitinol spring 140, to the adjusted pre-set pressure, i.e.
  • the fluid creating the secondary force acting on the bellows 136 can be removed from the pressure adjustment unit 130 into the set-point adjustment mechanism 180 by removing fluid through the septum 188 to deflate the expandable member 184. Accordingly, the removal of the fluid from the pressure adjustment unit 130 can change the pre-set pressure from the adjusted pre-set pressure, i.e. the pressure created by the nitinol spring 140 and the secondary force acting on the bellows 136, to the initial pre-set pressure, i.e. the pressure created by just the nitinol spring 140.
  • the set-point adjustment pressure of the set-point adjustment mechanism can vary from patient to patient, and thus the amount of fluid disposed in the expandable member 184 prior to achieving the set-point adjustment pressure can also change based on the patient.
  • the expandable member 184 can expand such that substantially all available space in the housing 182 is filled by the expandable member 184 disposed with fluid therein.
  • the set-point adjustment pressure can be achieved and the fluid can flow from the expandable member 184, through the exit port 190, and into the pressure adjustment unit 130.
  • the pre-set pressure of the pressure adjustment mechanism 230 can be adjusted by changing the tension of the torsion spring 250.
  • the housing 232 can include a port 270 (FIG. 3A) coupled thereto for receiving fluid.
  • a connector 260 can extend between the port 270 and the housing 232 and it can include a plug 254 movably disposed therein and coupled to a rotatable housing 258 that is rotatably disposed within housing 232.
  • a string 256 or other member can extend between the plug 254 and the housing 258.
  • a terminal end 252 of the torsion spring 250 can be coupled to the rotatable housing 232.
  • fluid added to and/or removed from the port 270 and the connector 260 will cause corresponding movement of the plug 254, which in turn will cause rotation of the rotatable housing 258.
  • the torsion spring 250 will wind or unwind with the housing 258, and thus the tension of the torsion spring 250 will be adjusted.
  • the pre-set pressure can be adjusted by altering the substantially constant force F of the constant force mechanism. At least because the substantially constant force F can define the pre-set pressure, any adjustment to the constant force mechanism that contributes to creating the substantially constant force F can be effective to adjust the pre-set pressure. This is illustrated, for example, in FIGS. 4B and 4C. Changing the force applied to the bearing element 350' by the cantilevered beam 352' can be effective to change the pre-set pressure because together they define the pre-set pressure.
  • a lever 356' is slidably positioned relative to the cantilevered beam 352' and is configured to change an effective length of the cantilevered beam 352' by sliding over a desired portion of the cantilevered beam 352'. Changing the effective length of the cantilevered beam 352' can change a normal force applied by the cantilevered beam 352' to the bearing element 350', which results in a changed substantially constant force F'.
  • the lever 356' can be coupled to a slidable block 358' and the slidable block 358' can be coupled to a means to supply linear motion.
  • the means to supply linear motion is a fluid system in which the slidable block 358' is disposed in a fluid chamber 360' that is configured to receive a fluid to slidably move the block 358' within the fluid chamber 360' to create slidable movement of the lever 356' attached thereto.
  • the slidable block 358', and hence the lever 356' can move between a first position, illustrated in FIG. 4B, in which the lever 356' is spaced apart from or out of contact with the cantilevered beam 352', and a second position, illustrated in FIG.
  • FIG. 4D illustrates yet another embodiment of a constant force mechanism 340'", similar to the constant force mechanism 340' of FIGS. 4B and 4C, that could also be incorporated into a distension system similar to the distension system 310' of FIGS. 4B and 4C.
  • the constant force mechanism 340'" includes a clamp mechanism 356'" for adjusting an effective length of the cantilevered beam 352'".
  • the clamping mechanism 356'" can be slidably disposed around the cantilevered beam 352'" and a base 358'" coupled to one end of the cantilever beam 352'".
  • the substantially constant force F" can be adjusted by changing the tension of the spring 350".
  • a height of the beam 345" can be increased or decreased to alter tension on the spring 350.
  • a proximal end 345p" of the cantilevered beam 345" can be pivotally coupled to a sidearm on the base 345b" and a rotational element 356" can be positioned just beneath the beam 345" such that rotation of the rotational element 356" adjusts the height of the beam 345".
  • a linkage 358" can be disposed between the rotational element 356" and the cantilevered beam 345" to assist in translating movement of the rotational element 356" to the cantilevered beam 345".
  • rotation of the rotational element 356" raises and lowers the cantilevered beam 345" to change an angle ⁇ " of the cam surface 348" while simultaneously increasing or decreasing the tension of the spring 350" to adjust the substantially constant force F".
  • clockwise rotation of the rotational element 356" lowers the cantilevered beam 345" and thus the value of the substantially constant force F'
  • counterclockwise rotation of the rotational element 356" raises the cantilevered beam 345" and thus increases the value of the substantially constant force F.
  • a pre-set pressure of the pressure adjustment unit 440 of FIG. 5 can be changed using friction.
  • the piston 452 can include the inflatable bladder 448 coupled thereto and in communication with a port 470. Adding fluid into the bladder 448 via the port 40 will increase a volume of the inflatable bladder 448. As the inflatable bladder 448 expands against the housing 442 an amount of friction between the inflatable bladder 448 and the housing increases. The friction affects the ability for the piston 452 to move, thus altering the pre-set pressure.
  • the pressure adjustment unit 540 of FIG. 6 can also have its pre-set pressure adjusted.
  • the pressure adjustment unit 540 can include a second bellows 550 coupled to the proximal end of the spring 548.
  • the second bellows 550 can be coupled to a second access port 552 formed in the proximal end 542p of the housing 542.
  • fluid can be added to or removed from the second bellows 550 to adjust a length of the spring 548 coupled thereto. Because the spring 548 defines the pre-set pressure, as its length changes, so does the pre-set pressure.
  • Pre-set pressures for the embodiments illustrated in FIGS. 7A and 7B can also be adjusted.
  • a composition of the saturated fluid 646, 646' can be changed.
  • a concentration of the saturated fluid 646, 646' can be changed.
  • either of these actions can be accomplished by connecting a port to the chamber 642, 642' containing the saturated fluid 646, 646' is disposed such that the composition and/or concentration of the saturated fluid can be changed by adding and/or removing fluid from the chamber 642, 642'.
  • the pre-set pressure of the pressure adjustment units 640, 640' can also be changed, at least because the saturated fluid 646, 646' defines the pre-set pressure.
  • the pre-set pressure for the embodiment illustrated in FIG. 8 can also be adjusted by changing a negative pressure of the evacuated volume 744, since the evacuated volume 744 defines the pre-set pressure. Although not illustrated, this too can be accomplished by connecting a port to the chamber 742 to access the evacuated volume 744.
  • the pre-set pressure of the osmotic pumps 840, 840', and 840" of FIGS. 9A-9D can also be adjusted in a variety of ways, but at least because the osmotic pressure of the osmotic chamber 848, 848', 848" defines the pre-set pressure, changes to the concentration of dissolved species in the fluid in the osmotic chamber 848, 848', 848" will also affect the pre-set pressure. For example, changing the molarity of the osmotic fluid contained in the osmotic chamber 848, 848', 848'” can be effective to adjust the preset pressure.
  • a port 870, 870', 870" in communication with the osmotic chamber 848, 848', 848" can be effective to change the molarity of the osmotic solution in a noninvasive manner.
  • FIG. 10 Yet another embodiment of a set-point adjustment mechanism 980 is illustrated in FIG. 10.
  • each of the pressure adjustment units described herein include a constant force mechanism.
  • Each of these constant force mechanisms, represented in FIG. 10 in their entirety by constant force mechanism 930 supply a substantially constant force F.
  • the set-point adjustment mechanism 980 can be generally applied to each and every embodiment disclosed because it is effective to adjust the resultant substantially constant force F once it leaves the constant force mechanism 930 and is communicated to another component, for example a fluid reservoir 970 in communication with a distension device 920.
  • a means to transfer the substantially constant force F from the constant force mechanism 930 to the fluid reservoir 970 can be disposed therebetween, and in the illustrated embodiment is a lever 982 having a piston 984 coupled to one end thereof and adapted to push fluid from the fluid reservoir 970 into the distension device 920 based on the substantially constant force F of the constant force mechanism 930.
  • a fulcrum 986 can be coupled to the lever 982 and it can be movable relative to the lever 982 to adjust a fulcrum point P of the lever 982. While the fulcrum 986 can be movable in a variety of ways, as shown it is slidably coupled to a surface 988.
  • a fluid port 990 can be in fluid communication with the fulcrum 986 by a transfer mechanism 992 and it can be adapted to cause movement of the fulcrum 986 along the surface 988 and relative to the lever 982 to change a location of the fulcrum point P.
  • a piston disposed within the fluid transfer mechanism 992 and coupled to the fulcrum 986 moves to thereby slide the fulcrum 986.
  • Changing the location of the fulcrum point P subsequently adjusts the mechanical advantage of the system to thus change the amount of the substantially constant force F that is actually applied to the fluid reservoir 970.
  • the optimal location for the fulcrum point P depends on a number of factors, including the amount of force acting on each portion of the lever 982, in an embodiment where the forces acting on each side of the lever 982 are equal, the optimal location for the fulcrum point P is the center of the lever 982.
  • the optimal location for the fulcrum point P is at the optimal location, the greatest amount of the substantially constant force F is transferred to the fluid reservoir 970.
  • the optimal location for the fulcrum point P will generally consistently change, which in turn means the fulcrum 986 should consistently be moved in order to maintain a desired efficiency of the system.
  • the fulcrum 986 moves to the left and the amount of the substantially constant force F that is transferred to the fluid reservoir 970 increases or decreases, depending on the location of the optimal fulcrum point.
  • the fulcrum 986 moves to the right, allowing the amount of the substantially constant force F that is transferred to the fluid reservoir 970 to increase or decrease, again depending on the location of the optimal fulcrum point.
  • the optimal location for fulcrum point P will likely be fluid as the system is operated, and thus, fluid can be selectively added to and removed from the fulcrum 986 to achieve a desired result from a desired location.
  • any of the pressure adjustment units, constant force mechanisms, and set-point adjustment mechanisms incorporate springs or other mechanical components that can be adjusted to provide different dimensions or properties (such as spring constants)
  • springs or other mechanical components that can be adjusted to provide different dimensions or properties
  • changes to many of the properties and dimensions will affect the performance of the respective pressure adjustment units, constant force mechanisms, and set-point adjustment mechanisms. Accordingly, even if changes to these types of components are not discussed above, such changes could be incorporated into many of the pressure adjustment units, constant force mechanisms, and set-point adjustment mechanisms to affect the desired performance of each.
  • the devices disclosed herein can be designed to be disposed of after a single use, or they can be designed to be used multiple times. In either case, however, the device can be reconditioned for reuse after at least one use. Reconditioning can include any combination of the steps of disassembly of the device, followed by cleaning or replacement of particular pieces, and subsequent reassembly. In particular, the device can be disassembled, and any number of the particular pieces or parts of the device can be selectively replaced or removed in any combination. Upon cleaning and/or replacement of particular parts, the device can be reassembled for subsequent use either at a reconditioning facility, or by a surgical team immediately prior to a surgical procedure.
  • the invention described herein will be processed before surgery.
  • a new or used instrument is obtained and if necessary cleaned.
  • the instrument can then be sterilized.
  • the instrument is placed in a closed and sealed container, such as a plastic or TYVEK bag.
  • the container and instrument are then placed in a field of radiation that can penetrate the container, such as gamma radiation, x- rays, or high-energy electrons.
  • the radiation kills bacteria on the instrument and in the container.
  • the sterilized instrument can then be stored in the sterile container.
  • the sealed container keeps the instrument sterile until it is opened in the medical facility.
  • device is sterilized. This can be done by any number of ways known to those skilled in the art including beta or gamma radiation, ethylene oxide, steam.

Abstract

L'invention concerne un système comprenant un implant conçu pour être disposé à l'intérieur d'un organe corporel creux. Le système comprend un élément rempli de fluide présentant une forme non déployée pour permettre l'administration à l'intérieur d'un corps creux et une ou plusieurs formes déployées pour permettre l'implantation à l'intérieur dudit corps creux. L'élément présente une rigidité suffisante dans sa forme déployée pour exercer une force vers l'extérieur contre un intérieur du corps creux de manière à rassembler deux surfaces du corps creux essentiellement opposées. Le système comprend également un moyen permettant de modifier la forme déployée de l'élément pendant son implantation à l'intérieur du corps creux. Le système comprend une unité d'ajustement de la pression qui communique avec l'élément de manière à maintenir une pression essentiellement constante à l'intérieur de l'élément.
PCT/US2009/062597 2008-10-30 2009-10-29 Mécanismes à force constante pour réguler des dispositifs de distension WO2010059381A1 (fr)

Applications Claiming Priority (2)

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US26110308A 2008-10-30 2008-10-30
US12/261,103 2008-10-30

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4222377A (en) * 1977-06-27 1980-09-16 American Medical Systems, Inc. Pressure regulated artificial sphincter systems
US20080058840A1 (en) * 2006-09-01 2008-03-06 Albrecht Thomas E Implantable coil for insertion into a hollow body organ
WO2008121409A1 (fr) * 2007-03-29 2008-10-09 Jaime Vargas Dispositifs d'implant intragastrique
EP2074970A1 (fr) * 2007-12-27 2009-07-01 Ethicon Endo-Surgery, Inc. Mécanismes de force constante pour la régulation de dispositifs de restriction

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4222377A (en) * 1977-06-27 1980-09-16 American Medical Systems, Inc. Pressure regulated artificial sphincter systems
US20080058840A1 (en) * 2006-09-01 2008-03-06 Albrecht Thomas E Implantable coil for insertion into a hollow body organ
WO2008121409A1 (fr) * 2007-03-29 2008-10-09 Jaime Vargas Dispositifs d'implant intragastrique
EP2074970A1 (fr) * 2007-12-27 2009-07-01 Ethicon Endo-Surgery, Inc. Mécanismes de force constante pour la régulation de dispositifs de restriction

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