WO2010056529A1

WO2010056529A1 - Sensor trigger

Info

Publication number: WO2010056529A1
Application number: PCT/US2009/062385
Authority: WO
Inventors: Thomas E. Albrecht; Jason L. Harris; Mark S. Ortiz; Amy L. Marcotte; Daniel F. Dlugos; Mark S. Zeiner; Michael J. Stokes
Original assignee: Ethicon Endo-Surgery, Inc.
Priority date: 2008-10-30
Filing date: 2009-10-28
Publication date: 2010-05-20

Abstract

An implant for placement within a hollow body organ including a distension system having an undeployed shape for delivery within a hollow body and one or more deployed shapes for implantation therein. The distension system has sufficient rigidity in its deployed shape to exert an outward force against an interior of the hollow body so as to bring together two substantially opposing surfaces of the hollow body. The implant includes a means for changing the deployed shape of the distension system while implanted within the hollow body. The implant also includes an implantable sensor in communication with the distension system, the sensor being defaulted to a dormant power usage mode and having a triggering mechanism configured to place the sensor in a use configuration upon the occurrence of a triggering event or events.

Description

SENSOR TRIGGER

This case is related to the following commonly assigned and concurrently filed U.S. Applications, all of which are hereby incorporated herein by reference:

U.S. Serial No. [ ] (Attorney Docket Number END6514USNP) titled DEVICES and METHODS FOR ADJUSTING A SATIATION AND SATIETY-INDUCING IMPLANTED DEVICE; U.S. Serial No. [ ] (Attorney Docket Number END6515USNP) titled Sensor Trigger; U.S. Serial No. [ ] (Attorney Docket Number END6516USNP) titled AUTOMATICALLY ADJUSTING INTRA-GASTRIC SATIATION AND SATIETY CREATION DEVICE; U.S. Serial No. [ ] (Attorney Docket Number END6517USNP) titled OPTIMIZING THE OPERATION OF AN INTRA-GASTRIC SATIETY CREATION DEVICE; U.S. Serial No. [ ] (Attorney Docket Number END6518USNP) titled POWERING IMPLANTABLE DISTENSION SYSTEMS USING INTERNAL ENERGY HARVESTING MEANS; U.S. Serial No. [ ] (Attorney Docket Number END6519USNP) titled WEARABLE ELEMENTS FOR INTRA- GASTRIC SATIETY CREATION SYSTEMS; U.S. Serial No. [ ] (Attorney Docket Number END6520USNP) titled INTRA-GASTRIC SATIETY CREATION DEVICE WITH DATA HANDLING DEVICES AND METHODS; U.S. Serial No. [ ] (Attorney Docket Number END652 IUSNP) titled GUI FOR AN IMPLANTABLE DISTENSION DEVICE AND A DATA LOGGER; U.S. Serial No. [ ] (Attorney Docket Number END6522USNP) titled METHODS AND DEVICES FOR FIXING ANTENNA ORIENTATION IN AN INTRA-GASTRIC SATIETY CREATION SYSTEM; U.S. Serial No. [ ] (Attorney Docket Number END6523USNP) titled METHODS AND DEVICES FOR PREDICTING INTRA-GASTRIC SATIETY CREATION DEVICE SYSTEM PERFORMANCE; U.S. Serial No. [ ] (Attorney Docket Number END6524USNP) titled CONSTANT FORCE MECHANISMS for Regulating Distension Devices; U.S. Serial No. [ ] (Attorney Docket Number END6525USNP) titled A METHOD OF REMOTELY ADJUSTING A SATIATION AND SATIETY-INDUCING IMPLANTED DEVICE. FIELD OF THE INVENTION

[0001] The present invention relates to methods and devices for effecting a gastric coil system, in particular, triggering a sensor of a gastric coil system.

BACKGROUND OF THE INVENTION

[0002] 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 proposed method of treating morbid obesity has been to place a distension device, such as a, spring loaded coil inside the stomach. Examples of 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. 11/469564, filed September 1, 2006, and pending U.S. Patent Application Serial No. 11/469,562, filed September 1, 2006, which are hereby incorporated herein by reference in their entirety. One effect of the coil is to more rapidly induce feelings of satiation defined herein as achieving a level of fullness during a meal that helps regulate the amount of food consumed. Another effect of the coil is to prolong the effect of satiety which is defined herein as delaying the onset of hunger after a meal which in turn regulates the frequency of eating. By way of a non-limiting list of examples, positive impacts on satiation and satiety may be achieved by an intragastric 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.

[0003] With each of the above-described stomach distension devices, safe, effective treatment requires that the device be regularly monitored and adjusted to vary the degree of distension applied to the stomach. .

[0004] It is often desirable to collect data concerning the operation of the distension system as well as concerning the physiological characteristics of the patient. Thus, some distension systems are equipped with a variety of sensors that can be configured to collect and transmit data that is useful for adjustment, diagnostic, monitoring, and other purposes. However, the operating power requirements of these sensors often make it prohibitive to maintain constant operation on an internal power source and there is thus a need to conserve power usage until required.

[0005] Accordingly, methods and devices are provided for use with a gastric distension device, and in particular for operating an internal sensor only when necessary.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0007] FIG. IA is a perspective view of one embodiment of a food intake distension system;

[0008] FIG. IB is perspective view of one embodiment of a distension system;

[0009] FIG. 2A is a perspective view of the gastric coil of the distension system shown in FIG. IB;

[0010] FIG. 2B is a perspective view of the gastric coil shown in FIG. 2A as applied to the gastro-esophageal junction of a patient;

[0011] FIG. 3 is a perspective view of the fluid injection port of the distension system shown in FIG. IB;

[0012] FIG. 4 is a perspective view of another embodiment of a distension system;

[0013] FIG. 5 is a block diagram of one embodiment of a pressure management system for use in conjunction with the distension system shown in FIG. 4;

[0014] FIG. 6A is a block diagram of one embodiment of a pressure management system having a triggering mechanism that includes a gastric pH sensor;

[0015] FIG. 6B is a block diagram of another embodiment of a pressure management system having a triggering mechanism that includes a gastric pH sensor;

[0016] FIG. 6C is a block diagram of another embodiment of a pressure management system having a triggering mechanism that includes a gastric pH sensor;

[0017] FIG. 6D is a schematic of an esophagogastric pH probe assembly used in a study to measure pH at various parts of the esophagus and stomach;

[0018] FIG. 6E shows the results from the study that measured the esophagogastric pH with a probe assembly similar to the one shown in FIG. 6D;

[0019] FIG. 7A is a block diagram of one embodiment of a pressure management system having a triggering mechanism that includes a temperature sensor;

[0020] FIG. 7B is a block diagram of another embodiment of a pressure management system having a triggering mechanism that includes a temperature sensor;

[0021] FIG. 7C is a block diagram of another embodiment of a pressure management system having a triggering mechanism that includes a temperature sensor;

[0022] FIG. 8A is a block diagram of one embodiment of a pressure management system having a triggering mechanism that includes a timer;

[0023] FIG. 8B shows the effect of a programmed timer, such as the one shown in FIG. 8A, on a pressure sensor of a distension system;

[0024] FIG. 9A is a perspective view of one embodiment of a triggering mechanism of a distension system as applied to a pressure sensor;

[0025] FIG. 9B is a perspective cross-sectional view of the triggering mechanism shown in FIG. 9A;

[0026] FIG. 9C is an enlarged view of the triggering mechanism shown in FIG. 9B;

[0027] FIG. 10 is a perspective view of one embodiment of a triggering mechanism of a distension system wherein the triggering mechanism includes an accelerometer; and

[0028] FIG. 11 is a perspective view of one embodiment of a triggering mechanism of a distension system wherein the triggering mechanism is actuated from within the stomach. DETAILED DESCRIPTION OF THE INVENTION

[0029] Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention.

[0030] The present invention generally provides devices and methods for effecting a gastric distension system. In one exemplary embodiment, a distension system for effecting a distension sensation in a patient is provided and can include an implantable distension device and an implantable sensor that is in communication with the distension device. In general, the implantable distension device can be adjustable and can be configured to cause a feeling of satiation and/or a prolonged sense of satiety in a patient. Exemplary non-limiting examples of 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. [ ], filed on even date herewith and entitled "Devices and Methods for Adjusting a Satiation and Satiety-Inducing Implanted Device" [Atty. Docket No. END6514USNP], which is hereby incorporated herein by reference in its entirety. The implantable sensor(s) can be defaulted to a dormant power usage mode and can have a triggering mechanism that is configured to place the sensor(s) in a use configuration upon the occurrence of a triggering event. In one exemplary embodiment, the implantable sensor(s) can be completely shut-off in the dormant power usage mode. In another embodiment, the dormant power usage mode can correspond to a low operating frequency, such as an operating frequency of less than or equal to 1 Hz. In general, the use configuration can have an operating frequency of about 2 to 20 Hz.

[0031] The distension system can also include an implantable port that is in fluid communication with the implantable distension device and is configured to receive fluid from a fluid source that is external to the patient. In one embodiment, the implantable sensor can be integrated with the implantable port. The triggering mechanism can be formed on the implantable sensor, the implantable port, or at another location within the distension system.

[0032] Various configurations are available for the triggering mechanism and the triggering event. Such configurations range from mechanisms that trigger the implantable sensor upon the detection of a change in a physiological characteristic of the patient to mechanisms that can be manually activated by the patient or physician.

[0033] In one exemplary embodiment, the triggering mechanism can include at least one gastric pH sensor and the triggering event is a change in gastric pH of a selected magnitude detected by the gastric pH sensor. In another embodiment, the triggering mechanism can include at least one pressure sensor that monitors pressures external to or within the distension system and the triggering event is a change in pressure of a selected magnitude or above/below a specified threshold detected by the pressure sensor. One non-limiting example is a fluid pressure sensor housed within a hydraulically adjustable distension system containing a fluid reservoir (an example of which has been incorporated by reference into this application). As the stomach applies loads to the distension system, the sensor monitors changes in the fluid pressure within the distension system. In yet another embodiment, the trigging mechanism includes a flexible membrane and the triggering event is an increase or decrease in pressure within the distension device that is effective to deflect the flexible membrane. The flexible membrane can be at least partially conductive and deflecting the membrane can be effective to complete an electrical circuit to energize the sensor and place it in the use configuration. In yet another embodiment, the triggering event may be the mechanical activation of a contact, limit, or proximity switch (ex. capacitive, inductive, optical) resultant from the flexing of the coil due to the peristaltic motions of the stomach in anticipation of or in reaction to food intact. Displacement or position sensors may also be used to trigger an event by sensing changes in position or angle of the distention system.

[0034] Another embodiment of a triggering mechanism includes an actuator and the triggering event includes actuation of the actuator. The triggering mechanism can also include a magnetic sensor and the triggering event includes generating at least one magnetic field thereby engaging the triggering mechanism. Another embodiment of a triggering mechanism can include an accelerometer and the triggering event includes transmitting vibratory energy within a selected frequency range transdermally to the accelerometer with an external actuator. Yet another embodiment of a triggering mechanism can include at least one temperature sensor and the triggering event includes a temperature change of a selected magnitude or frequency detected by the temperature sensor. The triggering mechanism can also include a timer programmed to place the sensor in the use configuration at pre-determined intervals. In one embodiment, the timer can be pre-programmed prior to implantation. The timer can also be configured such that it can be adjusted by an external device after implantation.

[0035] Methods for effecting a gastric distension system are also provided. In one exemplary embodiment, a method of effecting gastric restriction includes providing an implantable distension system, such as the one described above, triggering a sensor(s) of the distension system in response to a selected stimulus to energize the sensor(s) from a dormant power usage mode to a use mode, collecting data related to the operation of a distension device of the system via the sensor(s) when the sensor(s) is in the use mode, and transmitting the data collected by the sensor(s) to an external device when the sensor(s) is in the use mode. The method can also include adjusting the distension device in response to the data collected and transmitted by the sensor(s).

[0036] The present invention generally provides methods and devices for effecting a gastric distension system. In one exemplary embodiment, a distension system for effecting a sensation of satiation and/or satiety in a patient is provided and can include an implantable distension device and at least one implantable sensor that is in communication with the distension device. In general, the implantable distension device can be adjustable and can be configured to effect a sensation of satiation and/or satiety in a patient. The implantable sensor can be defaulted to a dormant power usage mode and can have a triggering mechanism that is configured to place the sensor in a use configuration upon the occurrence of a triggering event. The triggering mechanism can thus facilitate activation of the implantable sensor from the dormant power usage mode to the use mode in response to a selected stimulus. Various configurations are available for the triggering mechanism and the triggering event. Such configurations range from mechanisms that trigger the implantable sensor upon the detection of a change in a physiological characteristic of the patient to mechanisms that can be manually activated by the patient or physician. Upon the occurrence of the triggering event and activation of the implantable sensor to the use mode, the sensor can then collect data related to the operation of the distension device and transmit the collected data to an external device.

[0037] While the present invention can be used with a variety of distension systems known in the art, FIGS. IA and IB illustrate one exemplary embodiment of a food intake distension system 10. As shown, the system 10 generally includes an implantable portion 10a and an external portion 10b. The implantable portion 10a includes an adjustable gastric coil 20 that is configured to be positioned inside the patient's stomach 40. The sensor can have a variety of configurations and can be adapted to measure any number of operational parameters of the system and/or physiological characteristics of the patient. In one exemplary embodiment, shown in FIG. IA, the sensor takes the form of a pressure measuring device that is in fluid communication with the closed fluid circuit in the implantable portion 10a such that the pressure measuring device can measure the fluid pressure of the closed fluid circuit. While the pressure measuring device can have various configurations and it can be positioned anywhere along the internal portion 10a, including within the injection port 30, in the illustrated embodiment the pressure measuring device is in the form of a pressure sensor that is disposed within a sensor housing 60.

[0038] FIG. 2A shows the gastric coil 20 in more detail. While the gastric coil 20 can have a variety of configurations, and various gastric coils currently known in the art can be used with the present disclosure, in the illustrated embodiment the gastric coil 20 has a generally elongate shape with a support structure 22 having first and second opposite ends 20a, 20b that can be formed in a C-shape. Various techniques can be used to keep the ends 20a, 20b in relative proximity to one another. In the illustrated embodiment, the fluid bladder pressure may be varied to control the proximity of the ends relative to each other. The gastric coil 20 can also include a variable volume member, such as an inflatable balloon 24, that is disposed or formed on one side of the support structure 22 and that is configured to be positioned adjacent to tissue. The balloon 24 can expand or contract against the outer wall of the coil to form an adjustable size coil for controllably restricting food intake into the stomach. [0039] FIG. 2B shows the adjustable gastric coil 20 applied in the stomach of a patient. As shown, the coil 20 at least substantially distends the stomach 40. After the coil 20 is implanted, it may be deployed. A person skilled in the art will appreciate that various techniques, including mechanical and electrical techniques, can be used to adjust the coil.

[0040] As indicated above, the system can also include one or more sensors for monitoring the operation of the gastric distension system. The sensor(s) can be configured to measure various operational parameters of the system including, but not limited to, the pressure, pH, diameter, and temperature within the system. In one exemplary embodiment, the system can include a sensor in the form of a pressure measuring device that is in communication with the closed fluid circuit and that is configured to measure the fluid pressure, which corresponds to the amount of distension applied by the adjustable gastric coil to the patient's stomach. Measuring the fluid pressure enables a physician to evaluate the distension created by a coil adjustment. In the illustrated embodiment, the pressure measuring device is in the form of a pressure sensor that is disposed within a sensor housing 60. The pressure measuring device can, however, be disposed anywhere within the closed hydraulic circuit of the implantable portion. For example, in one embodiment, the implantable sensor can be integrated with the port. In general, as shown in FIG. 4, the illustrated housing 60 includes an inlet 60a and an outlet 60b that are in fluid communication with the fluid in the system. The sensor 62 is disposed within the housing 60 and is configured to respond to fluid pressure changes within the hydraulic circuit and convert the pressure changes into a usable form of data. While not shown, the pressure sensing system can also include a microcontroller, a TET/telemetry coil, and a capacitor. Optionally, the pressure sensing system can further comprise a temperature sensor (not shown). Microcontroller, TET/telemetry coil, and capacitor can be in communication via a circuit board (not shown) or via any other suitable component(s). It will also be appreciated that TET/telemetry coil and capacitor may collectively form a tuned tank circuit for receiving power from external portion, and transmitting the pressure measurement to the pressure reading device.

[0041] Various pressure sensors known in the art can be used, such as a wireless pressure sensor provided by CardioMEMS, Inc. of Atlanta, Georgia, though a suitable MEMS pressure sensor may be obtained from any other source, including but not limited to Integrated Sensing Systems (ISSYS), and Remon Medical. One exemplary MEMS pressure sensor is described in U.S. Patent No. 6,855,115, the disclosure of which is incorporated by reference herein for illustrative purposes only. It will also be appreciated that suitable pressure sensors may include, but are not limited to, capacitive, piezoresistive, silicon strain gauge, or ultrasonic (acoustic) pressure sensors, as well as various other devices capable of measuring pressure.

[0042] The pressure reading device 70 can also have a variety of configurations, and one exemplary pressure reading device is disclosed in more detail in commonly-owned U.S. Publication No. 2006/189888, entitled "Device for non-invasive measurement of fluid pressure in an adjustable restriction device," filed on February 24, 2005, and U.S. Publication No. 2006/0199997A1, entitled "Monitoring of a food intake restriction device," filed on April 6, 2006, which are hereby incorporated by reference in their entirety. In general, the pressure reading device 70 can non-invasively measure the pressure of the fluid within implanted portion. The physician may hold pressure-reading device 70 against the patient's skin adjacent the location of sensor and observe the pressure reading on a display on the control box 90. The pressure reading device 70 can also be removably attached to the patient, such as during a prolonged examination, using straps, adhesives, and other well-known methods. The pressure reading device 70 can operate through conventional cloth or paper surgical drapes, and can also include a disposal cover (not shown) that may be replaced for each patient.

[0043] FIG. 5 is a block diagram of one exemplary embodiment of a pressure measurement system for use in conjunction with the pressure sensor described above. As shown in FIG. 5, an external control module 126 of the system includes a primary TET coil 130 for transmitting a power signal to the internal control module, indicated generally as 132. Primary TET coil 130 is located in pressure reading device 60 shown in FIG. 1. A TET drive circuit 134 controls the application of a power signal to primary TET coil 130. TET drive circuit 134 is controlled by a microprocessor 136 having an associated memory 138. A graphical user interface 140 is connected to microprocessor 136 for controlling the data shown on display 66. External control module 126 also includes a primary telemetry transceiver 142 for transmitting interrogation commands to and receiving response data, including fluid pressure readings, from implant control module 132. Primary transceiver 142 is electrically connected to microprocessor 136 for inputting and receiving command and data signals. Primary transceiver 142 resonates at a selected RF communication frequency to generate a downlink alternating magnetic field 146 that transmits command data to implant control module 132. A power supply 150 supplies energy to external control module 126 in order to power system 30. An ambient pressure sensor 152 is connected to microprocessor 136. Microprocessor 136 uses the signal from ambient pressure sensor 152 to adjust the pressure reading for variations in atmospheric pressure due to, for example, variations in barometric conditions or altitude, in order to increase the accuracy of the pressure measurement.

[0044] FIG. 5 also illustrates internal control module 132 that can be implanted beneath the patient's skin 154. Internal control module 132 is located within the housing of the injection port. As shown in FIG. 5, a secondary TET/telemetry coil 156 in internal control module 132 receives power and communication signals from external control module 126. Coil 156 forms a tuned tank circuit that is inductively coupled with either primary TET coil 130 to power the implant, or primary telemetry coil 144 to receive and transmit data. A telemetry transceiver 158 controls data exchange with coil 156. Additionally, internal control module 132 includes a rectifier/power regulator 160, microcontroller 106 described above, a memory 162 associated with the microcontroller, temperature sensor 112, pressure sensor 84 and a signal conditioning circuit 164 for amplifying the signal from the pressure sensor. Internal control module 132 transmits the temperature adjusted pressure measurement from pressure sensor 84 to external control module 126. In external module 126, the received pressure measurement signal is adjusted for changes in ambient pressure and shown on a display.

[0045] As indicated above, the sensor element can be defaulted to a dormant power usage mode. A dormant power mode is intended to conserve usable power from an internal battery, capacitor, or other type of power storage. For example, in one exemplary embodiment, the implant can be partially dormant such that only the sensor interrogation portion of the circuit is powered continuously and another portion of the circuit, such as the telemetry circuit, is in a dormant or sleep mode. Such a configuration can reduce the power usage of the implant thereby reducing the required power capacity of an internal battery of the distension system. In general, it is not necessary for the sensor element to be continuously operating at full capacity. Thus, the sensor can be defaulted to the dormant power usage mode and energized when sensor readings are desirable, for example, when a patient is consuming food. In the default or dormant power usage mode the sensor is in a non-operational state (i.e., it is not actively sensing, collecting, or transmitting data related to an operating parameter of the system or physiological characteristic of a patient). In one exemplary embodiment, the implantable sensor can be completely shut-off in the dormant power usage mode. In another embodiment, the dormant power usage mode can correspond to a low operating frequency, such as an operating frequency of less than or equal to about 1 Hz. At the low operating frequency, some very low power functions can remain active such as a timer and some microcontroller functions. In general, the use configuration can have an operating frequency in the range of about 2 to 20 Hz. It shall be understood that higher or lower sampling frequencies can be used to conserve more or less power depending upon operational need of the system. Nyquist frequency or Nyquist rate principles can be used to determine the cut-off frequency of a given sampling system. The sampling frequency is intended to allow a sufficient sampling interval to detect a change in the physiologic feedback from the sensors. For example, in one exemplary embodiment, a pressure sensor can detect a higher pressure event at the lower sampling rate which can then signal the system to increase the sampling rate to capture and record data from the swallowing pulses. Alternatively, the peristaltic motions of the stomach in response to or even in anticipation of eating may trigger a mechanical actuation of a contact, limit or proximity switch to power on the sensor.

[0046] A triggering mechanism can be associated with the sensor and can be configured to place the sensor in a use configuration upon the occurrence of a triggering event. For example, the triggering mechanism can bring the system out of the dormant mode for some time to determine if the event or subsequent events require further action by the system. The triggering mechanism can be disposed at a variety of locations within the distension system. For example, in one exemplary embodiment, the triggering mechanism can be disposed on or integrally formed with the implantable sensor. In another embodiment, the triggering mechanism can be disposed on or integrally formed with the implantable port. Various configurations are available for the triggering mechanism and the triggering event. Such configurations range from triggering mechanisms that automatically energize the implantable sensor in response to a change in a physiological characteristic of the patient to triggering mechanisms that can be manually activated by the patient or physician. Various exemplary embodiments of triggering mechanisms and corresponding triggering events are described below.

[0047] In one exemplary embodiment, the triggering mechanism can include a gastric pH sensor and the triggering event can be a change in gastric pH of a selected magnitude. Variations in gastric pH can indicate whether or not there is food present in the stomach. The relationship between gastric pH levels and food consumption is explained in detail in "Regional Postprandial Differences in pH Within the Stomach and Gastroesophageal Junction," Digestive Diseases and Sciences, Vol. 50, No. 12 (December 2005), pgs. 2276-2285. In general, gastric pH is low in an empty stomach. Upon eating, especially foods that contain protein, gastric pH becomes more basic (i.e., the pH value increases) due to buffering by the food. The increase in pH occurs even though the stomach is actively secreting acid. Once the buffering capacity of the food is exceeded, the gastric pH returns to a low value. FIGS. 6D and 6E, which are reproduced from the above referenced article, illustrate the change in gastric pH over time. FIG. 6D is a schematic of an esophagogastric pH probe assembly that includes four pH probes disposed at various points in the esophagus and stomach. The pH probes, indicated by the X, are disposed in the distal esophagus, the proximal stomach, and the mid/distal stomach. FIG. 6E shows the results from a study that measured the esophagogastric pH with a similar probe assembly over a 27 hour period. As illustrated in FIG. 6E, the gastric pH increases after each meal and returns to the baseline pH sometime thereafter.

[0048] In another embodiment, the triggering mechanism can include a blood glucose sensor commonly found in blood glucose monitors. The sensor may be embedded within the gastric wall or small gastric artery. The sensor may be comprised of a layer containing two electrodes (silver or other similar metal). There also is a layer of the immobilized enzyme, glucose oxidase, and another layer containing microcrystalline potassium ferricyanide, [K₃Fe(CN)₆]. These layers are suitably separated by the spacers to allow for fluid communication

[0049] In an exemplary embodiment of a triggering mechanism, a contact switch is disposed on the body of the coil such that peristaltic contractions of the stomach may cause a change in location of the leads of the switch, causing an activation signal to be sent to the sensor to activate it. The switch may be a contact switch, requiring both physical contact and a given amount of pressure between the contacting elements, or a proximity switch which may be activated over a given gap between the elements of the switch. Typical proximity switches use a magnetic element as one of the contacts such that, when the magnetic field from the magnetic element is sufficiently strong on the receiving element, the switch is activated. Motion of the elements of the switch are effected by peristaltic motions of the stomach in reaction to or in anticipation of eating. The peristaltic motions of the stomach wall will cause flexure of the coil and cause the elements of the switch to move relative to each other, activating the switch. Alternatively the triggering mechanism includes at least one position sensor disposed in or on the body of the coil such that movement of the stomach may cause a change in the position of the coil. The position changes may be measured using for example such as LVDT (linear variable differential transformer) or DVRT (differential variable reluctance transformer} mechanical force, the motion of the stomach wall will cause flexure of the coil and cause the elements of the sensor to move relative to each other thereby creating a differential signal response. The differential response may be in the form of linear or angular position changes. The position sensor may be designed such that sufficient movement is required to trigger power from the dormant power usage mode to a use configuration.

[0050] FIG. 6A illustrates one exemplary embodiment of a triggering mechanism that includes a gastric pH sensor 600 for use with an implantable sensor of a distension system. For purposes of illustration, the triggering mechanism is shown in association with the pressure measurement system described above with respect to FIG. 5. However, one skilled in the art that will appreciate that the triggering mechanism can be used in conjunction with any type of sensor and its application should not be limited exclusively to pressure sensors or pressure measurement systems. As shown in FIG. 6A, the triggering mechanism takes the form of a gastric pH sensor 600 that is operatively associated with the pressure sensor 84. As discussed above, the gastric pH sensors can be positioned at numerous locations in the patient including, for example, the distal esophagus, the proximal stomach, and the mid/distal stomach. One skilled in the art will appreciate that one or more gastric pH sensors can be disposed at a variety of locations within the esophagus and stomach. The triggering event can generally be a change in gastric pH of a selected magnitude (e.g., |X - Y| pH). Alternatively, the triggering event can be a change in gastric pH that results in a pH range that is less than 7 pH. Thus, by way of a non-limiting example, in one exemplary embodiment, a change in gastric pH detected by the gastric pH sensor that is less than 7 pH can be effective to trigger the implantable sensor, thereby energizing the implantable sensor from the dormant power usage mode to a use configuration. One skilled in the art will appreciate that various techniques can be used to energize the system. In general, the pH sensor can send a signal to the implantable sensor to energize. In one exemplary embodiment, the signal can be sent by means of a direct connection between the pH sensor and the implantable sensor via a wired connection through the stomach (FIG. 6A). In another embodiment, the pH sensor can wirelessly communicate with the implantable sensor (FIG. 6B). In yet another embodiment, the pH sensor can transmit a signal to an external collection device that communicates the pH levels to the implantable sensor (FIG. 6C).

[0051] In another exemplary embodiment, the triggering mechanism can include a temperature sensor and the triggering event can be a change in temperature of a selected magnitude. Variations in temperature can indicate whether or not there is food present in the stomach. For example, an increase in temperature can indicate that food is being digested. FIG. 7 illustrates one exemplary embodiment of a triggering mechanism that includes a temperature sensor 700 for use with an implantable sensor of a distension system. For purposes of illustration, the triggering mechanism is shown in association with the pressure measurement system described above with reference to FIG. 5. However, one skilled in the art will appreciate that the triggering mechanism can be used in conjunction with any type of sensor and its application should not be limited exclusively to pressure sensors or pressure measurement systems. As shown in FIGS. 7A-7C, the triggering mechanism takes the form of a temperature sensor 700 that is operatively associated with the pressure sensor 84. One skilled in the art will appreciate that the temperature sensor 700 can be disposed at a variety of locations within the system including, for example, on the implantable sensor, the implantable port, or within the esophagus or stomach. Additionally, one or more temperature sensors can be employed. The triggering event can generally be a change in temperature of a selected magnitude, a selected occurrence, or exceeding a temperature set point. For example, in one exemplary embodiment, the triggering event can be a change in temperature that is greater than or equal to 3⁰F. Thus, in use, a change in temperature detected by the temperature sensor greater than or equal to 3⁰F can be effective to trigger the implantable sensor, thereby energizing the implantable sensor from the dormant power usage mode to a use configuration. In another embodiment, the triggering event can be reaching a predetermined temperature set point(s). In yet another embodiment, the triggering event can be a series of alternating temperature cycles such as hot/cold/hot. As with the pH sensor trigger described above, a variety of techniques can be used to energize the system. In general, the temperature sensor can send a signal to the implantable sensor to energize. In one exemplary embodiment, the signal can be sent by means of a direct connection between the temperature sensor and the implantable sensor via a wired connection through the stomach (FIG. 7A). In another embodiment, the temperature sensor can wirelessly communicate with the implantable sensor (FIG. 7B). In yet another embodiment, the pH sensor can transmit a signal to an external collection device that communicates the temperature to the implantable sensor (FIG. 7C). One skilled in the art will appreciate that several techniques can be used to communicate the signal from the temperature sensor to the implantable sensor.

[0052] Another exemplary embodiment of a triggering mechanism is shown in FIG. 8A. As shown, the triggering mechanism includes a timer 800 that can be programmed to place the sensor in the use configuration at pre-determined intervals. For purposes of illustration, the triggering mechanism is shown in association with the pressure measurement system described above with respect to FIG. 5. However, one skilled in the art will appreciate that the triggering mechanism can be used in conjunction with any type of sensor and its application should not be limited exclusively to pressure sensors or pressure measurement systems. As shown in FIG. 8A, the timer 800 is operatively associated with the pressure sensor 84. One skilled in the art will appreciate that the timer 800 can be disposed at a variety of locations within the system including, for example, on the implantable sensor or the implantable port The timer 800 can be programmed to activate the implantable sensor at a variety of time intervals. In general, the timer 800 can be programmed to activate the sensor at time intervals that correspond to the mealtimes of the patient. Various configurations are available for programming the timer. For example, in one exemplary embodiment, the timer can be pre-programmed prior to implantation. In another embodiment, an external device can be used to initiate a program or adjust an existing program of a timer that is already implanted. Such a configuration can allow for adjustment of the time intervals as more is known about the patient's eating habits thereby enabling the system to adapt to the patient's habits by increasing or decreasing the sampling rate as necessary. FIG. 8B illustrates the effect of a programmed timer on a pressure sensor of a distension system. As shown, pressure measurements are only recorded for the three programmed activation intervals, and the pressure sensor is in a non-operational state the remainder of the 24 hour period.

[0053] In yet another exemplary embodiment, the triggering mechanism can include a pressure sensor and the triggering event can be a change in pressure of a selected magnitude. Exemplary non-limiting examples of pressure sensors for use in this application are described in commonly owned and pending U.S. Patent Application Serial No. 11/682,459, filed on March 6, 2007, entitled "Pressure Sensors for Gastric Band and Adjacent Tissue," which is hereby incorporated herein by reference in its entirety. The "pressure trigger" can have a variety of configurations and can take many forms, but is generally directed to detecting a change in pressure of a selected magnitude within the closed fluid circuit of the gastric distension system. The physician is primarily concerned with pressures above a particular threshold, for example, lOmmHg for greater than 5 seconds. Thus, it is not necessary to actively sense and/or transmit data when the pressure within the closed fluid circuit is below this threshold. Further, when the pressure drops below the desired threshold after eating and peristalsis (i.e., the smooth muscle contractions that drive food distally through the esophagus, stomach, and intestines) are complete, the active components of the sensor can be shut-off entirely or can be defaulted to a low operating frequency to reduce power usage.

[0054] The "pressure trigger" can be an integral component of the pressure management system described above. For example, in one exemplary embodiment, the pressure sensor of the pressure management system can be configured to detect pressure changes of a selected magnitude at the low operating frequency of the dormant power usage mode. Thus, at the low operating frequency, only pressure changes of a selected magnitude are registered by the pressure sensor and the pressure sensor is not continuously sensing the fluid pressure within the system. Once the pressure sensor detects a change in pressure of a selected magnitude, for example, a change in baseline pressure that is greater than or equal tolOmmHg or a peak pressure greater than or equal to 60mmHg, the pressure sensor can be energized from the dormant state to the use configuration. One skilled in the art will appreciate that a variety of different values can be designated as the "selected magnitude," and the designation may vary from patient to patient. It can also be appreciated that the duration of the pressure magnitude may be factored in to determine if an authentic triggering event has occurred versus a transient event that does not require the system to be energized. A transient event can include, for example, a cough, a burp, and/or talking.

[0055] FIGS. 9A-9C illustrates another embodiment of a "pressure trigger." In this embodiment, the triggering mechanism 900 can include a flexible membrane 910 (FIGS. 9B and 9C) and the triggering event can be an increase in pressure within the distension device that is effective to deflect the flexible membrane 910. The flexible membrane 910 can be at least partially conductive such that an increase in pressure can be effective to deflect the membrane 910 to complete an electrical circuit to energize the sensor 920 and place it in the use configuration. As described below, a variety of configurations are available for the flexible membrane 910.

[0056] In one exemplary embodiment illustrated in FIGS. 9A-9C, the flexible membrane 910 is part of a metal capsule 930 that is disposed on a surface of a PC board 940 that contains the sensor electronics 945. The PC board 940 can generally be formed of a glass or ceramic material thereby allowing the metal capsule 930 to be brazed to a surface of the board 940. One surface 940a of the PC board 940 can contain the sensor electronics 945, and another surface 940b of the PC board 940 can have interlaced finger traces 950 formed thereon. The metal capsule 930 can be brazed onto the surface 940b of the PC board 940 containing the finger traces 950 thereby hermetically sealing the finger traces 950 from the fluid of the closed circuit. As shown in FIG. 9A, the metal capsule 930, PC board 940, and pressure sensor 920 can all be hermetically sealed within an outer capsule 960 to improve the long-term functioning of the device.

[0057] The circumference of the metal capsule 930 can be very stiff relative to the pressures of the fluid, and the flexible membrane 910 can extend across the stiff outer perimeter of the capsule 930 such that the flexible membrane 910 is allowed to deflect. A first surface 910a of the flexible membrane 910 can be in contact with the fluid 970 in the closed circuit. A second surface 910b of the flexible membrane 910 opposite the first surface 910a and not in contact with the fluid 970 in the system can have a conductive "pill" 980 disposed thereon. As shown in FIGS. 9B and 9C, the conductive "pill" 980 is disposed directly on the flexible membrane 910. In another exemplary embodiment, the conductive "pill" can be mounted on a flexible elastomeric element that is disposed between the flexible membrane and the conductive "pill." Such a configuration can electrically isolate the metal structure of capsule from the conductive "pill" as well as allow the membrane to flex in an arcuate fashion while the "pill" contacts at least two separate fingers simultaneously.

[0058] The conductive "pill" 980 can be configured to engage the finger traces 950 formed on the PC board 940. Under elevated pressure conditions, pressure from the fluid 970 within the closed circuit can deflect the flexible membrane 910 and push the conductive "pill" 980 into contact with the finger traces 950. The flexible membrane 910 can be configured to deflect at a pre-determined pressure. For example, in one embodiment a change in fluid pressure of lOmmHg can be effective to deflect the membrane 910 to cause the conductive "pill" 980 to engage the finger traces 950. In another exemplary embodiment, the flexible membrane 910 can be configured to deflect when the fluid pressure is greater than or equal to a pre-determined threshold value, such as 70 mmHg. The conductive "pill" 980 can make an electrical connection across the finger traces 950 thereby triggering the onboard circuitry contained in the PC board 940 to activate the sensor 920. When the pressure drops below the set point for a predetermined amount of time and the "pill" 980 is no longer in contact with the traces 950, the sensor 920 can return to the default dormant power usage mode.

[0059] In each of the embodiments described above, the triggering mechanism is configured to automatically activate the implantable sensor in response to a physiological change in the patient or other change within the distension system. The triggering mechanisms described below do not automatically activate the sensor in response to a system change but, instead, enable the patient or physician to activate the sensor at appropriate intervals, such as mealtimes.

[0060] In an exemplary embodiment, the actuator can be activated by magnetic force. For example, the actuator can include a ferromagnetic metallic component that is biased posteriorly with a spring force. In use, the patient or physician can pass a magnet over the actuator to overcome the spring force and allow the metallic component to move anterior and complete an electrical circuit thereby activating the sensor.

[0061] FIG. 10 illustrates another exemplary embodiment of a manually activated triggering mechanism. In this embodiment, the triggering mechanism can include an implantable accelerometer 1200 and the triggering event can include transmitting vibratory energy within a selected frequency range transdermally to the implantable accelerometer with an external actuator 1220. In general, an accelerometer is an electromechanical device that can measure acceleration forces such as, for example, dynamic forces caused by moving or vibrating the accelerometer. Thus, the patient or physician can use an external device 1220, such as a vibrating wand, to transmit vibratory energy through the skin to an implantable accelerometer 1200 disposed in the distension system 1230 to thereby activate the implantable sensor. The implantable accelerometer can be disposed on the implantable port, the implantable sensor, or at another suitable location within the distension system. Various types of accelerometers can be incorporated into the triggering mechanism including, for example, capacitive, piezoelectric, piezoresistive, Hall-effect, magnetoresistive, and heat transfer accelerometers. One skilled in the art will appreciate that vibratory energy within virtually any frequency range (and optionally for a selected period of time) can be selected to excite the accelerometer and thereby activate the sensor. For example, in one exemplary embodiment, the external device can transmit vibratory energy having a frequency that is greater than or equal to 1 to 3 Hz. As with the photoreceptor embodiment, the vibratory energy can be a single frequency or a series of pre-selected alternating frequencies (e.g., Morse Code) to prevent the accelerometer from inadvertently triggering from everyday activity. In another embodiment, the accelerometer may be an inclinometer, disposed to determine whether the patient is standing or reclining. During the reclining phase, it may turn off the sensor on the distension system since the patient is likely sleeping. While many overweight patients may eat in bed, this may be compensated for by turning off the device after a selected period of time after the inclinometer has detected a change in position of the patient.

[0062] Yet another embodiment of a manually activated triggering mechanism is shown in FIG. 11. In this embodiment, the triggering means can be transmitted from within the stomach. As shown in FIG. 11, the triggering mechanism includes a sensor element 1300 that is disposed in within the stomach 1310. The triggering event can include passing a triggering element 1320 through the stomach to thereby trigger the sensor element 1300 and activate the implantable sensor. For example, in one exemplary embodiment, the sensor element can be a temperature sensor that is configured to detect the internal temperature of the stomach. The triggering event can include changing the internal temperature of the stomach by having the patient ingest an alternating series of hot and cold liquids in a pre-determined pattern. Such a configuration can prevent the device from being inadvertently triggered when it is not mealtime and the patient simply ingests a hot or cold drink. In another embodiment, the sensor element can be a magnetic sensor that is configured to detect magnetic fields within the stomach. The triggering event can include generating a magnetic field within the stomach. The magnetic field can be generated by having the patient ingest a magnetic element such as a small magnetic pill or a magnetic powder that is mixed with food or drink. Thus, as the magnetic pill or powder passes through the patient's stomach, the magnetic field associated with the magnetic element is detected by the magnetic sensor thereby activating the implantable sensor.

[0063] Regardless of whether the implantable sensor is automatically energized in response to a change in operating parameter of the system or physiological characteristic of the patient or manually energized by the patient or physician, energizing the sensor is effective to place the sensor in the use configuration. In the use configuration, the sensor can collect data related to the operation of the distension device and transmit the collected data to an external device. The physician can then use the collected data to make adjustments to the distension system to optimize the performance of the system.

[0064] A person skilled in the art will appreciate that the present invention is described in the context of a pressure sensor being selectively activated from a dormant power usage mode to a use configuration. However, it is understood that a variety of other sensors (i.e., for detecting other physiological and non-physiological parameters) can be used in addition to or as an alternative to a pressure sensor. The present invention is also applicable to the triggering of such sensors to a use mode. Further any combination of these disclosed triggering means may be used in combination with each other, for example a timer may be used in conjunction with a temperature sensor of the stomach by having the patient ingest an alternating series of hot and cold liquids in a pre-determined pattern where the pattern is spaced out over a long period of time. If a series of sensor readings read the same over time the sensor could be used to shut off the sensor and bring it into a dormant power usage mode.

[0065] Any patent, publication, application or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated materials does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.

[0066] One skilled in the art will appreciate further features and advantages of the invention based on the above-described embodiments. Accordingly, the invention is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety.

Claims

What is claimed is:

1. An device for placement within a hollow body organ, said implant comprising:

a. a distension system having an undeployed shape for delivery within a hollow body and one or more deployed shapes for implantation therein; b. said distension system having sufficient rigidity in its deployed shape to exert an outward force against an interior of the hollow body so as to bring together two substantially opposing surfaces of said hollow body; c. a means for changing the deployed shape of said distension system while implanted within said hollow body; and d. an implantable sensor in communication with the distension system, the sensor being defaulted to a dormant power usage mode and having a triggering mechanism configured to place the sensor in a use configuration upon the occurrence of a triggering event or events.

2. The device of claim 1, further comprising an implantable port in fluid communication with the implantable distension device and configured to receive fluid from a fluid source external to the patient.

3. The device of claim 2, wherein the implantable sensor is integrated with the port.

4. The device of claim 2, wherein the triggering mechanism is formed on either the implantable sensor or the implantable port.

5. The device of claim 1, wherein the dormant power usage mode has an operating frequency less than or equal to about 1 Hz.

6. The device of claim 1, wherein the use configuration has an operating frequency in the range of about 2 to 20 Hz.

7. The device of claim 1, wherein the triggering mechanism includes at least one gastric pH sensor and the triggering event is a change in gastric pH of a selected magnitude detected by the gastric pH sensor.

8. The device of claim 1, wherein the triggering mechanism includes at least one gastric glucose sensor and the triggering event is a change in blood glucose of a selected magnitude detected by the gastric glucose.

9. The device of claim 1, wherein the triggering mechanism includes at least one pressure sensor and the triggering event is a change in pressure of a selected magnitude detected by the pressure sensor.

10. The device of claim 1, wherein the trigging mechanism includes a flexible membrane and the triggering event is a change in pressure within the distension device that is effective to deflect the flexible membrane.

11. The device of claim 1 , wherein the triggering mechanism includes a strain gauge and the triggering event is a change in strain.

12. the device of claim 1, wherein the triggering mechanism includes at least one switch and the triggering event is a change in relative location of the at least one elements of the switch

13. the switch of claim 12 wherein the switch is selected from the list of: contact switch, limit switch, proximity switch

14. the device of claim 1, wherein the triggering mechanism includes at least one sensor and the triggering event is a change in relative movement of the at least one element of the member.

15. the sensor of claim 14 wherein the sensor is selected from the list of: proximity sensor, position sensor, force sensor, motion sensor

16. The device of claim 10, wherein the flexible membrane is at least partially conductive and deflecting the membrane is effective to complete an electrical circuit to energize the sensor and place it in the use configuration.

17. The device of claim 1, wherein the triggering mechanism is an actuator and the triggering event includes actuation of the actuator.

18. The device of claim 1, wherein the triggering mechanism includes a magnetic sensor and the triggering event includes generating at least one magnetic field thereby engaging the triggering mechanism.

19. The device of claim 1, wherein the triggering mechanism includes an accelerometer and the triggering event includes transmitting vibratory energy within a selected frequency range transdermally to the accelerometer with an external actuator.

20. The device of claim 1, wherein the triggering mechanism includes an Radio Frequency Receiver and the triggering event includes transmitting a Radio Frequency signal within a selected frequency range wirelessly to the receiver with an external transmitter.

21. The device of claim 1, wherein the triggering mechanism includes an accelerometer and the triggering event includes changing the inclination of the patient to or from the supine position to indicate that the patient is going to sleep or waking up

22. The device of claim 1, wherein the triggering mechanism includes an accelerometer and the triggering event is a change in the acceleration and vibration forces measured by the accelerometer as a result of the peristaltic motions of the stomach in anticipation of or in reaction to food intact.

23. The device of claim 1, wherein the triggering mechanism includes at least one temperature sensor and the triggering event includes a temperature change of a selected magnitude or frequency detected by the temperature sensor.

24. The device of claim 1, wherein the triggering mechanism includes a timer programmed to place the sensor in the use configuration at pre-determined intervals.

25. The device of claim 24, wherein the timer is pre-programmed prior to implantation.

26. The device of claim 24, wherein the timer can be adjusted by an external device.

27. The device of claim 24, wherein the timer can be adjusted or reset by data collected by the sensor.