Flexible tube sensor for sensing urinary sphincter pressure
The disclosure describes a therapeutic sphincter control system with a fluid tube pressure sensor. The system senses sphincter pressure and sends the information to a stimulator that is capable of stimulation therapy to control sphincter contractility, thus reducing unwanted urinary incontinence. Measuring sphincter pressure is accomplished through the use of a fluid-filled tube placed through the sphincter and attached to a module implanted within the bladder. Pressure within the tube is transduced to generate an electrical signal that is sent wirelessly to an implanted stimulator connected to a lead positioned near pelvic floor nerves. An external device may be used to wirelessly send information to the implanted stimulator and inhibit stimulation in order for the patient to empty the bladder. Pressure information and stimulation information may be recorded and reviewed for continued patient monitoring. In addition, the system may only include the pressure sensor to monitor patient pressure information.
1. An implantable electrical stimulation system comprising:
an implantable pressure sensor including a housing, a flexible tube containing fluid extending from the housing to a distal end, and a sensing element mounted within the housing that senses a pressure level exerted by a sphincter on the flexible tube at a region of the tube spaced from the distal end when the tube is placed proximate to the sphincter; and
an implantable stimulator that is adapted to deliver electrical stimulation to tissue that affects the pressure exerted by the sphincter; and
a processor adapted to receive the pressure level exerted by the sphincter as sensed by the sensing element and control the the implantable stimulator to modulate the pressure exerted by the sphincter based on a threshold pressure.
2. The system of claim 1 , wherein the flexible tube includes a closed end and an open end, and the sensing element is disposed at the open end.
3. The system of claim 2 , wherein the sensing element includes a flexible membrane that generates an electrical signal based on deformation of the membrane by pressure within the flexible tube.
4. The system of claim 3 , wherein the flexible membrane includes a strain gauge sensor.
5. The system of claim 1 , wherein the flexible tube has a length of less than approximately 7 cm and an outer diameter of approximately 1 to 3 mm.
6. The system of claim 1 , wherein the implantable pressure sensor includes a fixation mechanism to position the flexible tube proximate a urinary sphincter within a patient.
7. The system of claim 6 , wherein the fixation mechanism is positioned to attach the housing to an inner wall of a bladder of the patient.
8. The system of claim 1 , wherein the implantable sensor includes a telemetry circuit that transmits information based on the sensed pressure level.
9. The system of claim 8 , wherein the telemetry circuit transmits the information to the implantable stimulator, the implantable stimulator adjusting one or more parameters of the electrical stimulation based on the transmitted information.
10. The system of claim 9 , further comprising an external programmer to adjust stimulation parameters associated with the electrical stimulation delivered by the implantable stimulator, wherein the telemetry circuit transmits the information to the external programmer.
11. The system of claim 1 , wherein the implantable stimulator includes a lead carrying one or more electrodes to deliver electrical stimulation to a nerve site that innervates the sphincter,
12. The system of claim 1 , wherein the implantable sensor includes a plurality of implantable sensors having flexible tubes disposed at different positions within a urinary tract
13. The system of claim 1 , further comprising a cystoscopic deployment device to deploy the implantable pressure sensor, the deployment device defining a cavity to carry the sensor housing and a channel to accommodate the flexible tube extending from the housing.
14. The system of claim 1 , wherein the sensing element senses a pressure level exerted by a urinary sphincter within a patient, and the implantable stimulator provides electrical stimulation to control urinary incontinence.