Abstract: An occlusion system implantable in a human or animal body, including a fluidic circuit which includes an inflatable occlusive sleeve, a reservoir with variable volume filled with a fluid. The reservoir includes a fixed portion and a movable portion, an actuator mechanically coupled with the movable portion of the reservoir to linearly displace the movable portion relative to the fixed portion for adjusting the volume of the reservoir. The actuator and the reservoir are laid out in a sealed casing containing a gas. A sensor mechanically bound to the actuator and/or to the movable portion, measures a traction and/or compressive force of the movable portion of the reservoir. Also included is a device for measuring the fluid pressure in the fluidic circuit.

Abstract: A device for improving environmental perception for blind or visually impaired users, including a set of mechanical actuators intended to be in contact with the skin of a user, at least one digital camera designed to acquire a current digital image of an environment facing the user, a processing circuit connected to the camera for receiving pixel signals from the acquired digital image and converting at least one portion of the pixel signals into control signals, each of which powers a mechanical actuator of the set of actuators, an eye-tracking module for tracking each eye of the user to identify a gaze direction of the user. The processing circuit then selects, in the environment filmed by the camera, an area of acquired current image which is a function of the gaze direction and converts the pixel signals of said area into control signals, each of which powers an actuator of the set to stimulate the user's skin.

Abstract: Devices, systems, and methods for reducing stress on a blood vessel are disclosed herein. A damping device (100) configured in accordance with embodiments of the present technology can include an anchoring member (104) coupled to a flexible, compliant damping member (102) including a generally tubular sidewall having an outer surface (115), an inner surface (113) defining a lumen configured to direct blood flow, a first end portion (106) and a second end portion (108), and a damping region (120) between the first and second end portions (106, 108). The inner and outer surfaces (113, 115) of the damping member (102) can be spaced apart by a distance that is greater at the damping region (120) than at either of the first or second end portions (106, 108).

Abstract: A medical device for narrowing or closing an anatomical channel includes a band part (1) which can be placed around the body tissue (2) surrounding the anatomical channel and which can be closed to form a ring that encloses a through-opening (6) for the body tissue, wherein the band part (1) has a hollow chamber (3), and wherein the through-opening (6) can be made smaller by introducing a fluid into the hollow chamber (3). The medical device moreover includes a pump unit (10) which serves to convey the fluid and which has an electric drive (15) controllable by an electronic control system of the device, wherein a pressure value corresponding to the pressure of the fluid in the hollow chamber (3) or dependent on this pressure can be detected by the electronic control system. The device moreover has an air pressure sensor (23) for detecting the atmospheric pressure.

Abstract: An occlusion system implantable in a human or animal body, including a fluidic circuit which includes an inflatable occlusive sleeve, a reservoir with variable volume filled with a fluid. The reservoir includes a fixed portion and a movable portion, an actuator mechanically coupled with the movable portion of the reservoir to linearly displace the movable portion relative to the fixed portion for adjusting the volume of the reservoir. The actuator and the reservoir are laid out in a sealed casing containing a gas. A sensor mechanically bound to the actuator and/or to the movable portion, measures a traction and/or compressive force of the movable portion of the reservoir. Also included is a device for measuring the fluid pressure in the fluidic circuit.

Abstract: An intra-vaginal device for controlling urinary incontinence, designed to be placed longitudinally in the vagina, includes: a. a deformable distal portion, placed in the subvesical region of the vagina, characterized by a deformable state and an un-deformable state; b. a deformable proximal portion placed in the sub-urethral portion of the vagina, characterized by a deformable state and an un-deformable state; c. a deformation controlling mechanism interconnecting said distal portion and said proximal portion, adapted to reversibly transform said distal portion and said proximal portion form said deformable state to said un-deformable state; and from said un-deformable state to said deformable state; wherein upon predetermined amount of intra-vaginal pressure applied on said proximal portion, said deformation controlling mechanism is adapted to transform proximal portion from its un-deformable state to its deformable state such that pressure is applied on said urethra.

Abstract: The disclosure relates generally to an extended use systems and devices for management of bladder function for people with urinary dysfunction. The system includes a catheter which can include a sensor that can determine bladder condition and a valve that can control fluid flow. The catheter can be placed inside the bladder using devices that facilitate insertion and extraction. The placement of the catheter can be done by a trained individual such as a patient, as well as a clinician, a nurse, or a caretaker. Once placed inside the bladder, the catheter can be fully-internal, meaning no portion of the catheter is visible from outside of the patient's body.

Abstract: A sphincter assist device includes a plurality of interconnected and adjacent links which define a ring. Each link includes a body section and a latch cam. The body section includes a first set of side beams and a first set of snap arms. The latch cam includes a post extending from the body section and a cam disposed at an end portion of the post. The cam is engagable with the first set of snap arms of an adjacent link. Translation of the cam displaces the first set of snap arms and the first set of side beams to transition the sphincter assist device between open and closed configurations. The first set of snap arms, in combination with the first set of side beams, exert a positive non-linear force profile on the cam, thus defining a non-linear force profile of the sphincter assist device between the open and closed configurations.

Abstract: A connector for connecting a pressure sensing catheter to charger is provided. The connector can include a first engagement portion engageable with a charger engagement portion of the charger to displace a pressure transmission medium in the charger engagement portion to charge one or more balloons of the pressure sensing catheter. The connector can have a handle that includes a tab terminating in an end surface engageable with an engagement surface of the charger when the first engagement portion engages with the charger engagement portion. The connector includes a distal abutment portion that engages with a portion of the charger engagement portion to provide an audible or tactile feedback, so as to prevent inadvertent overcharging of the balloons.

Abstract: A catheter hub assembly includes a body. A pressure sensor is disposed within the body to sense pressure within a catheter and communicating with the body The body has a chamber formed therein having a predetermined volume. A stopper assembly, slideably moves to engage the body forming a gastight seal within the chamber for pushing a column of gas ahead of the stopper assembly as the stopper assembly moves from a first position to a second position.

Abstract: Where an implanted reservoir (140) for intestinal contents is formed from surgically modified intestine (70) that has been cut along a mutual contact line of laterally adjacent sections of a bent portion of intestine and connected so that the resulting upper and lower halves of the intestine form an intestinal wall of the reservoir, the system for emptying such intestinal reservoir comprises an artificial flow body and adapted to control flow of the intestinal reservoir comprises an artificial flow control device (160) implantable in the patient's body and adapted to control flow of the intestinal contents from said reservoir, the flow control device comprising at least one pump adapted to act on said intestinal wall so as to reduce the reservoir's volume, thereby emptying the reservoir. The system may further comprise an entry valve upstream of the reservoir and an exit valve downstream from the reservoir.

Abstract: An implantable vital sign sensor including a housing including a first portion, the first portion defining a first open end, a second open end opposite the first end, and a lumen there through, the first portion being sized to be implanted substantially entirely within the blood vessel wall of the patient. A sensor module configured to measure a blood vessel blood pressure waveform is included, the sensor module having a proximal portion and a distal portion, the distal portion being insertable within the lumen and the proximal portion extending outward from the first open end.

Abstract: An apparatus for treating regurgitation of blood through a diseased heart valve having at least two leaflets includes a lollipop-shaped body member having a proximal end portion, a distal end portion, and an intermediate portion extending between the end portions. The intermediate portion includes an expandable occluding member having an adjustable diameter so that, during at least a portion of the cardiac cycle, at least one of the heart leaflet coapts with a portion of the occluding member to mitigate or prevent regurgitation of blood through the diseased heart valve. The proximal end portion is physically connected to the occluding member and includes a connecting mechanism for operably mating with an adjustment member for adjusting the position and diameter of the occluding member within the diseased heart valve. The distal end portion includes an anchoring member for securing the apparatus in a heart chamber containing the diseased heart valve.

Abstract: Disclosed herein are devices and methods for intra-vaginal bowel control.

Abstract: There is disclosed a method for treating anal incontinence in women. The method comprises accessing the rectum or colon or anus though an incision in the vagina and implanting a powered restriction device on the rectum, colon or anal sphincter. There are also disclosed methods for energizing and controlling the restriction device.

Abstract: A device for repositioning an implant within a lumen of a subject including (a) a catheter having forward and rearward ends and a collapsible and expansible stop element mounted adjacent the forward end of the catheter, the stop element being adapted to engage a wall of the lumen when expanded and to provide one or more passages extending from a rear side of the stop element to a forward side of the stop element when the stop element is expanded and engaged with the wall of the lumen and (b) one or more snares, each snare having engagement features, the stop element and the snares being constructed and arranged so that the snares can be positioned extending through the one or more passages with their engagement features forward of the stop element.

Abstract: The present invention relates to an implantable apparatus for obtaining urinary control and emptying of the urinary bladder, thereby preventing from or treating involuntary urinary retention. In general terms, the apparatus comprises an expandable member adapted to be implanted inside the urinary bladder of the patient for discharging urine, and a control device for controlling the volume of the expandable member. The control device is adapted to be connected to the expandable member through the wall of the urinary bladder.

Abstract: Systems and methods are provided and adapted to engage and pull (e.g., pull up) or reposition urethral support tissue, such as the portion of the perineal membrane above or below the urethra. The perineal membrane intersects the urethra and vagina at the midurethra or distal location and can thus be stabilized or controlled in a manner that helps restore continence.

Abstract: The present invention provides an artificial sphincter employing an easily controlled electro-mechanical pump system. The artificial sphincter includes an inflatable cuff, a control pump fluidly coupled to the inflatable cuff, and an electro-mechanical pump system. The inflatable cuff is adapted to surround a urethra or rectum of the patient to facilitate continence. An inflation element or balloon can be included to further control pressure to the cuff.

Abstract: An artificial urinary sphincter (AUS) system includes a pump attachable with tubing between a pressure regulating reservoir and a cuff. The cuff is configured for placement around a portion of a urethra and has a frame with at least one inflatable balloon attached to the frame. A gap is formed from a top edge to a bottom edge of the frame, where the gap provides the rigid frame with a C-shaped conformation in lateral cross-section having a first lateral section separated from a second lateral section. Each inflatable balloon(s) is/are attached to an interior surface on one of the first lateral section or the second lateral section of the frame.

Abstract: Systems and methods are provided and adapted to engage and pull (e.g., pull up) or reposition paraurethral support tissue, such as the perineal membrane. The perineal membrane intersects the urethra and vagina at the midurethra or distal location and can thus be stabilized or controlled in a manner that helps restore continence. As such, the implants can be utilized to eliminate the need for mesh or other supportive structures under the urethra that is common with other incontinence slings.

Abstract: Various embodiments of an implant system for treating fecal incontinence are provided. The devices and systems can include a mesh or like device that can include a variable porosity to control the degree of expansion of the anal canal. The mesh can be constructed at least in part of patterned strut members allowing for various geometric configurations, with varying load and tension properties for the designated portions of the device according to the needs for a particular patient application.

Abstract: An artificial urinary sphincter system includes a cuff implantable around a portion of a urethra, an implantable pressure-regulating reservoir, and a deflation assembly attachable between the cuff and the implantable pressure-regulating reservoir. The deflation assembly includes a valve that selectively restricts movement of the fluid from the cuff to the pressure-regulating reservoir, a base and an activation surface opposite the base. The activation surface includes an outer peripheral rim surrounding a pad that is movable to displace the valve to allow the fluid to flow from the cuff to the pressure-regulating reservoir. An entirety of the pad is recessed relative to the outer peripheral rim such that the outer peripheral rim defines a maxima of the activation surface.

Abstract: A totally implantable method for occluding the urethra or bladder neck utilizing an occlusive cuff connected to a control mechanism via a conduit tube. The occlusive cuff is reversibly changed from an activated (occlusive condition) to a de-activated (non-occlusive) condition by depressing a deactivation button contained within a resilient, elastomeric sheath surrounding the control mechanism. The occlusive condition is once again obtained by depressing an activation button also situated within the resilient sheath. In the occlusive condition, a preset tension is applied to a flexible diaphragm through a tensioning suture by a constant force spring contained within the control mechanism. This tension is translated into an occlusive pressure applied to the urethra or bladder neck sufficient to prevent urinary leakage.

Abstract: An incontinence treatment device includes a support, a pump, and anchors each attached to a connection line. The support includes an inflatable bladder and the pump is body-implantable and attachable to the inflatable bladder. The pump is configured to selectively inflate the inflatable bladder to compress the tissue of the urethra. The connection lines are attached to the support. A first anchor is fixed to the first connection line and a second anchor is coupled to the second connection line, where the second anchor is an adjustable anchor. The adjustable anchor is configured to be movable and position-adjustable relative to the second connection line.

Abstract: A method of treating urinary incontinence in a patient includes providing an incontinence treatment device including a first connection line attached to a support, a second connection line attached to the support, and an inflatable bladder attached to the support, with an adjustable anchor coupled to one of the connection lines. The method includes creating a perineal incision in the patient; and directing the adjustable anchor through the perineal incision and inserting the anchor into tissue on one side of the patient. The method includes sliding one of the connection lines through the adjustable anchor and adjusting a position of the support relative to a urethra of the patient.

Abstract: An implantable apparatus for controlling fluid flow within a host body includes a constricting member for allowing fluid flow within a body canal when in an open position, and for reducing fluid flow within a body canal when in an closed position. Remote telemetry can be used to operate the constricting member from a position outside the body. The constricting member can include a piston having at least two protrusions for contacting the vessel surface of the body canal. A fluid-operated member can receive fluid to reduce fluid flow within the body canal and expel fluid to allow fluid flow within the body canal. An actuating member is provided for operating the fluid-operated member between the open and closed positions. The actuating member has structure for flowing fluid into and out of the fluid-operated member. A control device is provided for operating the actuating member.

Abstract: The present invention relates generally to dynamic support devices, methods of providing dynamic support to target tissues, and kits comprising these devices. These devices may have particular utility in providing support to the urethra. The dynamic support devices generally comprise at least one attachment member for attachment to bodily tissue, and at least one support member, where the device capable of assuming a first configuration and a second configuration. The dynamic support devices may be configured to support a target tissue when the device is in its second configuration. The support member may comprise one or more rotating components, one or more deformable components, one or more sliding components, or a combination thereof.

Abstract: An incontinence treatment device and method of treating urinary incontinence in a person includes fabricating an artificial urethra to have a flow diameter formed inside of a circumferential wall and a closure device attached directly to a portion of an outer surface of the circumferential wall of the artificial urethra. The artificial urethra is sized to be spliced to a natural urethra for alignment of the flow diameter of the artificial urethra with a lumen of the natural urethra. A pump is provided for moving liquid out of a reservoir and into the closure device to push the outer surface of the circumferential wall into the flow diameter of the artificial urethra, which operates to close the flow diameter of the artificial urethra.

Abstract: A urinary tract valve includes an expandable valve element positionable within a bladder of a patient via a urinary tract of the patient in a collapsed configuration. The expandable valve element is configured to transition from the collapsed configuration to an expanded configuration after being positioned within the bladder of the patient. The expandable valve element includes a ferromagnetic element that facilitates selective control of the expandable valve element with a magnetic field between an open position and a closed position when positioned within the bladder of the patient. In the closed position, the expandable valve element is configured to seal an internal urethral opening of the patient. In the open position, the expandable valve element is configured to allow urine to pass from the bladder of the patient, through an internal urethral opening of the patient and into a urethra of the patient.

Abstract: An incontinence treatment device includes a section of synthetic urethra and a closure device attached to the section of synthetic urethra. The section of synthetic urethra provides a flow diameter and is configured to be spliced into a natural urethra such that the flow diameter is aligned with a lumen of the natural urethra for passage of urine. The closure device is attached to the section of synthetic urethra and operable to coapt the flow diameter to allow a user to impede the passage of urine and be continent.

Abstract: An anal incontinence treatment apparatus comprises an adjustable restriction device implanted in a patient, who suffers from anal incontinence. The device engages a portion of the colon or rectum of the patient to restrict the fecal passageway. An adjustment device mechanically adjusts the restriction device to restrict or release the fecal passageway, i.e. to normally close the fecal passageway and open the fecal passageway when the patient wants to relieve himself or herself.

Abstract: A totally implantable method for occluding the urethra or bladder neck utilizing an occlusive cuff connected to a control mechanism via a conduit tube. The occlusive cuff is reversibly changed from an activated (occlusive condition) to a deactivated (non-occlusive) condition by depressing a deactivation button contained within a resilient, elastomeric sheath surrounding the control mechanism. The occlusive condition is once again obtained by depressing an activation button also situated within the resilient sheath. In the occlusive condition, a preset tension is applied to a flexible diaphragm through a tensioning suture by a constant force spring contained within the control mechanism. This tension is translated into an occlusive pressure applied to the urethra or bladder neck sufficient to prevent urinary leakage.

Abstract: Using a sling that includes a central portion and at least two arms extending from the central portion, a method of treating anal incontinence may include positioning the central portion posteriorly to the rectum and/or anus of a subject, and extending each arm of the sling to a respective obturator region. Using a sling having the same or similar structure, a method of treating pelvic organ prolapse may include positioning the central portion beneath the ano-rectum of a subject, and extending each arm of the sling to a respective thigh incision near the obturator region.

Abstract: An artificial urinary sphincter system has a pressure reservoir attachable to a pump and a conduit attachable between the pump and a cuff. The cuff is formed as a one-piece monolithic polymer structure that is substantially circular in radial cross-section. The cuff has an interior wall connected by a pair of opposing end walls to an exterior wall and includes a closed cavity located between the interior wall and the exterior wall. The cuff has a part line that allows for placement of the cuff around a urethra of a user.

Abstract: A device for treating urinary incontinence. The device comprising a body having a passage, for accommodating a urethra of a patient, extending from an inlet to an outlet of the device. The passage being configured so as to normally induce a flow obstruction in the urethra, following surgical implantation of the device. The flow obstruction, induced by the device, being sufficiently pliable and deformable so that once an internal system pressure within the urethra becomes sufficiently great, the internal system pressure overcomes the flow obstruction, induced by the device, and creates a flow passage through the device.

Abstract: An apparatus for cleansing and promoting tissue growth in wounds, in which irrigant fluid optionally containing cell nutrients and/or other physiologically active material from a reservoir connected to a conformable wound dressing and wound exudate from the dressing are recirculated by a device for moving fluid through a flow path which passes through the dressing, a biodegradable scaffold in contact with the wound bed and a means for fluid cleansing and back to the dressing. The apparatus has means for supplying thermal energy to the fluid in the wound. The cleansing means (which may be a single-phase, e.g. micro-filtration, system or a two-phase, e.g. dialytic system) removes materials deleterious to wound healing, and the cleansed fluid, still containing materials that are beneficial in promoting wound healing, is returned to the wound bed. The dressing and a method of treatment using the apparatus.

Abstract: In some embodiments, an apparatus includes a handle and an elongate member coupled to the handle. The elongate member has a first portion, a second portion and a third portion. The first portion of the elongate member extends from the handle and defines a first longitudinal axis. The second portion of the elongate member extends from the first portion and defines a second longitudinal axis. The first longitudinal axis and the second longitudinal axis define a first angle and a first plane. The third portion of the elongate member extends from the second portion of the elongate member and defines a third longitudinal axis. The third longitudinal axis and the second longitudinal axis define a second angle and a second plane. The second plane is non-parallel with the first plane.

Abstract: An artificial urinary sphincter (AUS) system includes a pump attachable with tubing between a pressure regulating reservoir and a cuff. The cuff is configured for placement around a portion of a urethra and has a frame with at least one inflatable balloon attached to the frame. A gap is formed from a top edge to a bottom edge of the frame, where the gap provides the rigid frame with a C-shaped conformation in lateral cross-section having a first lateral section separated from a second lateral section. Each inflatable balloon(s) is/are attached to an interior surface on one of the first lateral section or the second lateral section of the frame.

Abstract: An artificial urinary sphincter (AUS) system includes a cuff, a pump, and a conduit attachable between the cuff and the pump. The cuff is integrated to include a first compartment and a storage compartment. The first compartment is configured to contact the urethra and the storage compartment communicates with the first compartment. The pump is operable to move the liquid between the first compartment and the storage compartment. The cuff is a pressurizable reservoir that is sized to be placed around a urethra of a user and configured to coapt the urethra in treating urinary incontinence.

Abstract: An artificial urinary sphincter (AUS) system includes a cuff, a pump, and a single tube that provides the system with an inflatable storage compartment. The single tube is connected between the cuff and the pump and includes a first lumen communicating between the cuff and the pump and a separate second lumen communicating between the cuff and the pump. The cuff is inflatable with a cuff volume of liquid that is sized to selectively close the urethra for treatment of urinary incontinence. The pump is operable to move the cuff volume of liquid out of the cuff to provide the cuff with a deflated state that allows the urethra to open and pass urine. The second lumen has a storage compartment sized to retain the cuff volume of liquid.

Abstract: A stomal implant comprising a longitudinal portion configured to envelop at least a section of the bowel or ileal conduit, said longitudinal portion comprising: a proximal end for positioning at a stomal opening; a distal end for positioning within an abdomen; and a reversibly pressure-exerting device providing an ascending pressure gradient from the distal end to the proximal end, such that pressure exerted at the proximal end provides complete closure of the bowel or urethra.

Abstract: An apparatus for cleansing and applying therapy or prophylaxis to wounds, in which irrigant fluid containing a physiologically active material from a reservoir connected to a conformable wound dressing and wound exudate from the dressing are recirculated by a device for moving fluid through a flow path which passes through the dressing and a means for fluid cleansing and back to the dressing. A biodegradable scaffold underlies the dressing on the wound bed to promote tissue growth. The cleansing means (which may be a single-phase, e.g. micro-filtration, system or a two-phase, e.g. dialytic system) removes materials deleterious to wound healing, and the cleansed fluid, still containing materials that are beneficial in promoting wound healing, is returned to the wound bed. The dressing, an assembly comprising the dressing and scaffold, and a method of treatment using the apparatus.

Abstract: A negative pressure wound therapy apparatus that can include a wound dressing, a fluid collection device, a vacuum pump comprising a pump motor, and tubing can be powered by auxiliary power sources such as high efficiency batteries, photovoltaic panels or cells, fuel cells, combustion generators, human powered generators, or other mechanical, electrical, or chemical power sources such as hand operated dynamos or wound springs, or any combination of the foregoing. Additionally, the apparatus can include a high efficiency pressure controller for controlling the output of the vacuum pump. In some embodiments, the pressure controller can control the pump without using a processor, and can have other features such as an intermittent delay function and an anti-stall mechanism to reduce the energy consumption of the apparatus.

Abstract: A remotely controllable gastric banding device (10) for placement around the stomach of a patient for the treatment of obesity. The device (10) comprises a gastric band (10) having an inflatable chamber (16) for adjusting the inner circumference of the band (10), a pressurized reservoir (20) with a valve (31) for providing fluid to inflate the inflation chamber (16), a valve (32) for releasing fluid from the inflatable chamber (16), and a controller (41) for controlling the valves (31, 32). The controller (41) is remotely controllable from outside the patient.

Abstract: Devices and methods for intra-vaginal bowel control.

Abstract: A sensor for use in a canister for fluid collection, the canister having a canister top and defining a fluid collection chamber. The sensor includes a first electrode and a second electrode. The first electrode includes a first portion and a second portion, wherein the first portion of the first electrode is supported by the canister top, and the second portion of the first electrode is configured to extend into the fluid collection chamber. The second electrode includes a first portion and a second portion, wherein the first portion of the second electrode is supported by the canister top, and the second portion of the second electrode is configured to extend into the fluid collection chamber. The sensor also includes an electric circuit configured to detect an electrical property associated with the first and second electrodes.

Abstract: An implantable pump for pumping fluid to or from a hydraulic surgical implant inside a human's or an animal's body comprises a wall forming a chamber for the fluid, the wall including a base plate and a membrane, which is displaceable relative to the base plate to change the volume of the chamber to pump the fluid between the chamber and the surgical implant. The membrane is penetrable by an injection needle to add hydraulic fluid to or withdraw hydraulic fluid from the chamber, in order to calibrate the amount of fluid, and the membrane is self-sealing to seal the hole which is formed in the membrane by the penetrating injection needle. The implant typically is a hydraulic constriction device, which can be designed for treating reflux disease, urinary incontinence, impotence, anal incontinence or obesity.

Abstract: A fluid transfer system for an inflatable sphincter prosthesis is disclosed. The implantable inflatable sphincter prosthesis may include a fluid transfer system and at least one inflatable cuff for occluding a body channel. The fluid transfer system may include an inflate pump, a deflate pump, and three one-way valves.

Abstract: A urination control device includes a conduit to be inserted into the urethra, an upstream restraint member located upstream of the conduit and having a through hole, a control member located on the downstream side from the upstream restraint member in the conduit, and a downstream restraint member located on the downstream side from the control member in the conduit, wherein the upper restraint member and control member attract each other with magnetic force, and the control member is brought in contact with the opening portion of the through hole in the upstream restraint member at least in the state exerting no fluid pressure on the upstream side so as to block passage of fluid through the upstream restraint member and admit the passage of fluid through the downstream restraint member in the state engaged with the control member.