Abstract:
An implant for placement within a hollow body organ. The implant includes an implantable distension device having an undeployed shape for delivery within a hollow body and one or more deployed shapes for implantation therein. The implantable distension device 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 powered means for changing the deployed shape of the implantable distension device while implanted within the hollow body. The implant also includes an implantable sensing device in communication with the implantable distension device and configured to sense a parameter related to the implantable distension device and to communicate the parameter to a filter, the filter transmits a selected portion of the parameter to a data storage device.

Description:
[0001]    This case is related to the following commonly assigned and concurrently filed U.S. Applications, all of which are hereby incorporated herein by reference: 
         [0002]    U.S. Ser. No. ______ (Attorney Docket Number END6514USNP) titled DEVICES and METHODS FOR ADJUSTING A SATIATION AND SATIETY-INDUCING IMPLANTED DEVICE; U.S. Ser. No. ______ (Attorney Docket Number END6515USNP) titled Sensor Trigger; U.S. Ser. No. ______ (Attorney Docket Number END6516USNP) titled AUTOMATICALLY ADJUSTING INTRA-GASTRIC SATIATION AND SATIETY CREATION DEVICE; U.S. Ser. No. ______ (Attorney Docket Number END6517USNP) titled OPTIMIZING THE OPERATION OF AN INTRA-GASTRIC SATIETY CREATION DEVICE; U.S. Ser. No. ______ (Attorney Docket Number END6518USNP) titled POWERING IMPLANTABLE DISTENSION SYSTEMS USING INTERNAL ENERGY HARVESTING MEANS; U.S. Ser. No. ______ (Attorney Docket Number END6519USNP) titled WEARABLE ELEMENTS FOR INTRA-GASTRIC SATIETY CREATION SYSTEMS; U.S. Ser. No. ______ (Attorney Docket Number END6520USNP) titled INTRA-GASTRIC SATIETY CREATION DEVICE WITH DATA HANDLING DEVICES AND METHODS; U.S. Ser. No. ______ (Attorney Docket Number END6521USNP) titled GUI FOR AN IMPLANTABLE DISTENSION DEVICE AND A DATA LOGGER; U.S. Ser. No. ______ (Attorney Docket Number END6522USNP) titled METHODS AND DEVICES FOR FIXING ANTENNA ORIENTATION IN AN INTRA-GASTRIC SATIETY CREATION SYSTEM; U.S. Ser. No. ______ (Attorney Docket Number END6523USNP) titled METHODS AND DEVICES FOR PREDICTING INTRA-GASTRIC SATIETY CREATION DEVICE SYSTEM PERFORMANCE; U.S. Ser. No. ______ (Attorney Docket Number END6524USNP) titled CONSTANT FORCE MECHANISMS for Regulating Distension Devices; U.S. Ser. No. ______ (Attorney Docket Number END6525USNP) titled A METHOD OF REMOTELY ADJUSTING A SATIATION AND SATIETY-INDUCING IMPLANTED DEVICE. 
     
    
     FIELD OF THE INVENTION 
       [0003]    The present invention relates to devices and methods for handling data related to implantable distension devices. 
       BACKGROUND OF THE INVENTION 
       [0004]    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 Ser. No. 11/469,564, filed Sep. 1, 2006, and pending U.S. patent application Ser. No. 11/469,562, filed Sep. 1, 2006, which are hereby incorporated herein by reference in their entirety. One effect of the distension device 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 distension device 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 distension device 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. 
         [0005]    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. 
         [0006]    During these distension device adjustments, it may be difficult to determine how the adjustment is proceeding, and whether the adjustment will have the intended effect. 
         [0007]    Additionally, it can be advantageous to acquire data indicating the pressure in a distension device before, during, and/or after pressure adjustment for adjustment, diagnostic, monitoring, or other purposes. It can be further advantageous to store such pressure data and/or communicate it to an external location. However, data storage space can be limited, and power to communicate data can be resource-intensive. 
         [0008]    Accordingly, methods and devices are provided for use with a gastric distension device, and in particular for handling data gathered in relation to a gastric distension device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0010]      FIG. 1A  is a perspective view of an embodiment of a stomach distension system; 
           [0011]      FIG. 1B  is a side view of an embodiment of an implantable portion of the stomach distension system of  FIG. 1A ; 
           [0012]      FIG. 2A  is a cross sectional view of the stomach distension device of  FIG. 1A ; 
           [0013]      FIG. 2B  is a schematic diagram of the stomach distension device of  FIG. 2A  applied about within the stomach of a patient; 
           [0014]      FIG. 3  is a perspective view of an embodiment of the injection port housing of  FIG. 1A ; 
           [0015]      FIG. 4  is a side view of an embodiment of the sensor housing of  FIG. 1A ; 
           [0016]      FIG. 5  illustrates an embodiment of the sensor housing of  FIG. 1A ; 
           [0017]      FIG. 6  is a schematic of an embodiment of a variable resistance circuit for the pressure sensor of  FIG. 5 ; 
           [0018]      FIG. 7  is a block diagram showing an embodiment of internal and external components of the stomach distension device of  FIG. 1A ; 
           [0019]      FIG. 8  is a flow diagram showing an embodiment of a data handling protocol for the stomach distension device of  FIG. 1A ; 
           [0020]      FIG. 9  is a graphical representation of a pressure measurement from the pressure sensor of  FIG. 5 ; 
           [0021]      FIG. 10  is a graphical representation of another pressure measurement from the pressure sensor of  FIG. 5 ; 
           [0022]      FIG. 11  is a schematic diagram of an embodiment of a data logger for recording pressure measurements related to the stomach distension device of  FIG. 1A ; 
           [0023]      FIG. 12  is a block diagram showing an embodiment of components of the data logger of  FIG. 11 ; 
           [0024]      FIG. 13  is a schematic diagram of an embodiment of a data logging system for recording pressure measurements related to the stomach distension device of  FIG. 1A ; 
           [0025]      FIG. 14  is a is a block diagram showing an embodiment of components of the data logging system of  FIG. 13 ; 
           [0026]      FIG. 15  is a perspective view of an embodiment of a stomach distension system with a sensor positioned along a catheter; 
           [0027]      FIG. 16  is a schematic view of an embodiment of a stomach distension system with a sensor positioned within a catheter; 
           [0028]      FIG. 17  is a perspective view of another embodiment of a stomach distension system with a sensor positioned along a catheter; and 
           [0029]      FIG. 18  is a schematic view of an embodiment of a gastric coil system with a “T”-shaped sensor and catheter configuration. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    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 of 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. 
         [0031]    The present invention generally provides devices and methods for handling data related to implantable distension devices. The distension device may also be adjustable. 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 Ser. 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. In one embodiment, a distension system for forming a distension in a patient is provided that includes an implantable distension device that can cause a distension in a patient and an implantable sensing device in communication with the implantable distension device. The implantable sensing device can sense a clinically relevant parameter related to the implantable distension device and communicate a selected portion of data to an external device considering a variation of data from a nominal parameter value related to the implantable distension device. By way of a non-limiting list, the parameter can include at least one of, for example, stomach pH, pressure, pulse count, pulse width, and amplitude. In some embodiments, the selected portion of data is compressed prior to communication of the selected portion of data to the external device. 
         [0032]    The sensing device can be implemented in a variety of ways. For example, the sensing device can communicate data to the external device when the external device telemetrically provides at least some power to the sensing device. As another example, the sensing device can discard data that substantially equals a nominal value. For yet another example, the sensing device can communicate a selected portion of data based on whether the data includes a value within a defined range of values. As still another example, the sensing device can compare data with a nominal value. For another example, the sensing device can store the selected portion of data prior to communication of the selected portion of data to the external device. 
         [0033]    In another embodiment, a distension system for forming a distension in a patient includes an implantable distension device that can cause a distension in a patient&#39;s stomach, an implantable pressure sensing device in communication with the implantable distension device that can sense a pressure within the implantable distension device, and a processor (which can be included in the implantable pressure sensing device) that can determine whether to store any of the sensed pressure data prior to communicating any of the sensed pressure data to an external reading device. The processor, in some embodiments, can have a download of stored data to the external reading device triggered when the external reading device is moved in proximity of the implantable pressure sensing device. In some embodiments, the system can also include an external storage mechanism that can store sensed pressure data, communicate stored pressure data to an external device, and, optionally, be removably attached to the patient. 
         [0034]    In other aspects, a method of forming a distension in a patient is provided. The method includes using an implantable pressure sensing device to obtain pressure data related to a pressure within an implantable distension device that can cause a distension in a patient, storing at least a portion of obtained pressure data at the implantable pressure sensing device, and triggering a download of stored pressure data when an external device is moved in proximity of the implantable pressure sensing device. The obtained pressure data stored at the implantable pressure sensing device can include pressure values that exceed a nominal pressure within the implantable distension device. In some embodiments, the method can also include compressing at least a portion of obtained pressure data prior to storing the at least a portion of the obtained pressure data at the implantable pressure sensing device. The compression can be performed using at least one compression technique, such as storing difference values, using a quantization table, using run-length coding, and using Huffman coding. 
         [0035]    In another embodiment, a method of forming a distension in a patient includes obtaining pressure data related to a pressure within an implantable distension device that can cause a distension in a patient. In some embodiments, obtaining pressure data includes reducing a rate of pressure data gathering during a determined period. The method further includes determining a portion of the pressure data to retain prior to communicating pressure data to an external reading device. Determining a portion of the pressure data to retain can include determining if any of the obtained pressure data includes a value within a defined range of pressure values, determining to retain any of the obtained pressure data that exceeds a nominal pressure within the implantable distension device, and/or processing the obtained pressure data using a pressure sensing device (e.g., a processor) coupled to the implantable distension device and configured to obtain the pressure data. An alert for communication to the external reading device can be generated if any of the obtained pressure data includes a value that exceeds a threshold pressure value. In some embodiments, the method also includes storing only the portion of the pressure data determined to be retained prior to communicating pressure data to the external reading device. In still other embodiments, the method also includes compressing the portion of the pressure data determined to be retained prior to storing the portion of the pressure data determined to be retained. 
         [0036]    In yet another embodiment, a method of forming a distension in a patient includes using an implantable pressure sensing device to obtain pressure data related to a pressure within an implantable distension device that can cause a distension in a patient, storing the obtained pressure data at the implantable pressure sensing device, and compressing the obtained pressure data prior to storing the obtained pressure data. The obtained pressure data can be compressed using at least one compression technique, such as storing difference values, using a quantization table, using run-length coding, and using Huffman coding. The method can also include communicating at least a portion of the compressed and stored pressure data from the pressure sensing device to an external device. It is understood that whereas pressure may be measured and stored, a variety of other parameters including peristaltic pulse count, pulse width, pulse amplitude, pulse duration, pH, temperature, acceleration and other relevant physiologic parameters. 
         [0037]    The present invention generally provides devices and methods for handling data related to implantable distension devices. In general, the devices and methods allow collection, analysis, storage, and transmission of measurements related to any parameter related to implantable distension devices, such as pressure, pulse count, pulse width, and amplitude, pH, temperature, acceleration and other physiologically relevant parameters. While the methods and devices discussed herein can relate to any sensed data parameter, in an exemplary embodiment, the measurements relate to pressure. Pressure measurements can help accurately evaluate the performance of and determine any advisable pressure adjustments of an implantable distension device, but not all collected pressure data may be helpful in making such evaluations and determinations. Furthermore, handling pressure measurement data can drain power resources of an implantable distension system and can use costly, physically bulky, and electronically large data storage space. Pressure measurement data can be compressed before storing it, thereby using less storage space, time, power, and/or bandwidth for communication than for the corresponding, uncompressed data. Pressure measurement data can also be compressed prior to communication. The data can be compressed and directly transmitted, or the compressed data stored in memory can be recalled and communicated wirelessly when interrogated. Additionally, not all pressure data need be recorded or retained. Not recording or retaining all pressure data, such as data substantially equaling a resting or nominal pressure of the implantable distension device indicative of little to no pressure variation and data indicative of isolated, non-recurring events, can save storage space for potentially more analytically valuable pressure measurement data and reduce the amount of physical and/or electronic storage space used for pressure measurements. Any pressure measurement data that is recorded can be transmitted to an external device using power telemetrically provided or inductively coupled by the external device, thereby reducing or eliminating power supply resources local to the storage location of recorded data. 
         [0038]    While the present invention can be used with a variety of distension systems known in the art,  FIG. 1A  illustrates one exemplary embodiment of a stomach distension system  10  in use in a patient. As shown, the system  10  generally includes an implantable portion  10   a  and an external portion  10   b .  FIG. 1B  illustrates the implantable portion  10   a  outside of a patient. As shown, the implantable portion  10   a  includes an adjustable gastric coil  20  that is configured to be positioned in a patient&#39;s stomach  40 , and an injection port housing  30  that is fluidly coupled to the adjustable gastric coil  20 , e.g., via a catheter  50 . The injection port  30  is adapted to allow fluid to be introduced into and removed from the gastric coil  20  to thereby adjust the size of the coil  20  and thus the pressure applied to the stomach  40 . The injection port  30  can thus be implanted at a location within the body that is accessible endoscopically. Typically, injection ports are positioned on the distension device. 
         [0039]    The internal portion  10   a  can also include a sensing or measuring device that is in fluid communication with the closed fluid circuit in the implantable portion  10   a . In one embodiment, the sensing device is a pressure sensing device configured to 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  10   a , including within the injection port  30  and as described further below, in the illustrated embodiment the pressure measuring device is in the form of a pressure sensor that is disposed within a sensor housing  60  positioned adjacent to the injection port  30 . The catheter  50  can include a first portion that is coupled between the gastric coil  20  and the pressure sensor housing  60 , and a second portion that is coupled between the pressure sensor housing  60  and the injection port  30 . While it is understood that the sensing device can be configured to obtain data relating to one or more relevant parameters, generally it will be described herein in a context of a pressure sensing device. 
         [0040]    In addition to sensing pressure of fluid within the internal portion  10   a  as described herein, pressure of fluid within the esophagus and/or the stomach  40  can also be sensed using any suitable device, such as an endoscopic manometer. By way of non-limiting example, such fluid pressure measurements can be compared against measured pressure of fluid within the internal portion  10   a  before, during, and/or after adjustment of pressure within the internal portion  10   a . Other suitable uses for measured pressure within the esophagus and/or the stomach  40  will be appreciated by those skilled in the art. 
         [0041]    As further shown in  FIG. 1A , the external portion  10   b  generally includes a data reading device  70  that is configured to be positioned on the skin surface above the sensor housing  60  to non-invasively communicate with the sensor housing  60  and thereby obtain data (e.g., pressure) measurements. The data reading device  70  can optionally be electrically coupled (wirelessly or wired, as in this embodiment via an electrical cable assembly  80 ) to a control box  90  that can display the pressure measurements and/or other data obtained from the data reading device  70 . While shown in this example as located local to the patient, the control box  90  can be at a location local to or remote from the patient, as explained further below. 
         [0042]      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  20   a ,  20   b  that can be formed in a C-shape. Various techniques can be used to keep the ends  20   a ,  20   b  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 inner wall of the coil to form an adjustable size coil for controllably restricting food intake into the stomach. 
         [0043]    A person skilled in the art will appreciate that the gastric coil can have a variety of other configurations. Moreover, the various methods and devices disclosed herein have equal applicability to other types of implantable coils. 
         [0044]      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. 
         [0045]    The fluid injection port  30  can also have a variety of configurations. In the embodiment shown in  FIG. 3 , the injection port  30  has a generally cylindrical housing with a distal or bottom surface and a perimeter wall extending proximally from the bottom surface and defining a proximal opening  32 . The proximal opening  32  can include a needle-penetrable septum  34  extending there across and providing access to a fluid reservoir (not visible in  FIG. 3 ) formed within the housing. The septum  34  is preferably placed in a proximal enough position such that the depth of the reservoir is sufficient enough to expose the open tip of a needle, such as an endoscopic Huber-like needle, so that fluid transfer can take place. The septum  34  is preferably arranged so that it will self seal after being punctured by a needle and the needle is withdrawn. As further shown in  FIG. 3 , the port  30  can further include a catheter tube connection member  36  that is in fluid communication with the reservoir and that is configured to couple to a catheter (e.g., the catheter  50 ). A person skilled in the art will appreciate that the housing can be made from any number of materials, including stainless steel, titanium, or polymeric materials, and the septum  34  can likewise be made from any number of materials, including silicone. 
         [0046]    The 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. 2006/0189888 and U.S. Publication No. 2006/0199997, which are hereby incorporated by reference. In general, the data reading device  70  can non-invasively measure the pressure of the fluid within the implanted portion  10   a  even when the pressure sensing device is implanted beneath thick (at least over 10 cm) subcutaneous fat tissue in the patient&#39;s stomach. The physician can hold the reading device  70  against the patient&#39;s skin near the location of the sensor housing  60 , and/or other pressure sensing device location(s), and observe the pressure reading on a display on the control box  90 . The data reading device  70  can also be removably attached to the patient, as discussed further below, such as during a prolonged examination, using straps, adhesives, and other well-known methods. The data 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. Furthermore, the reading device may be operated using an endoscopic probe which may be inserted down the mouth of the patient to close proximity with the coil. 
         [0047]    As indicated above, the system  10  can also include a pressure measuring device in communication with the closed fluid circuit and configured to measure pressure (e.g., fluid pressure) which corresponds to the amount of distension applied by the adjustable gastric coil  20  to the patient&#39;s stomach  40 . Measuring the pressure enables a person (e.g., a physician, a nurse, a patient, etc.) to evaluate the efficacy and functionality of the distension created by a coil adjustment. In the illustrated embodiment, as shown in  FIG. 4 , the pressure measuring device is in the form of a pressure sensor  62  disposed within the sensor housing  60 . The pressure measuring device can, however, be disposed anywhere within the closed hydraulic circuit of the implantable portion, and various exemplary locations and configurations are disclosed in more detail in commonly-owned U.S. Publication No. 2006/0211913 entitled “Non-Invasive Pressure Measurement In a Fluid Adjustable Restrictive Device,” filed on Mar. 7, 2006, and hereby incorporated by reference. In general, the illustrated sensor housing  60  includes an inlet  60   a  and an outlet  60   b  that are in fluid communication with the fluid in the implantable portion  10   a . An already-implanted catheter  50  can be retrofitted with the sensor housing  60 , such as by severing the catheter  50  and inserting barbed connectors (or any other connectors, such as clamps, clips, adhesives, welding, etc.) into the severed ends of the catheter  50 . The sensor  62  can be disposed within the housing  60  and be configured to respond to fluid pressure changes within the hydraulic circuit and convert the pressure changes into a usable form of data. 
         [0048]    Various pressure sensors known in the art can be used as the pressure sensor  62 , such as a wireless pressure sensor provided by CardioMEMS, Inc. of Atlanta, Ga., though a suitable MEMS pressure sensor may be obtained from any other source, including but not limited to Integrated Sensing Systems, Inc. (ISSYS) of Ypsilanti, Mich. and Remon Medical Technologies, Inc. of Waltham, Mass. One exemplary MEMS pressure sensor is described in U.S. Pat. No. 6,855,115, the disclosure of which is incorporated by reference herein for illustrative purposes only. It will also be appreciated by a person skilled in the art that suitable pressure sensors can 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. 
         [0049]    One embodiment of a configuration of the sensor housing  60  having the sensor  62  disposed within it is shown in  FIG. 5 . The sensor housing  60  in this example includes a motherboard that can serve as a hermetic container to prevent fluid from contacting any elements disposed within the sensor housing  60 , except as discussed for the sensor  62 . The sensor housing  60  can be made from any biocompatible material appropriate for use in a body, such as a polymer, biocompatible metal, and other similar types of material. Furthermore, the sensor housing  60  can be made from any one or more of transparent (as shown in  FIG. 5 ), opaque, semi-opaque, and radio-opaque materials. A circuit board  64  including, among other elements, a microcontroller  65  (e.g., a processor), can also be disposed within the housing  60  to help process and communicate pressure measurements gathered by the sensor  62 , and also possibly other data related to the coil  20 . As further discussed below, the circuit board  64  can also include a transcutaneous energy transfer (TET)/telemetry coil and a capacitor. Optionally, a temperature sensor can be integrated into the circuit board  64 . The microcontroller  65 , the TET/telemetry coil, the capacitor, and/or the temperature sensor can be in communication via the circuit board  64  or via any other suitable component(s). The TET/telemetry coil and capacitor can collectively form a tuned tank circuit for receiving power from the external portion  10   b , and transmitting pressure measurements to a pressure reading device, e.g., the reading device  70 . Moreover, to the extent that a telemetry component associated with the pressure sensor  62  is unable to reach a telemetry device external to the patient without some assistance, such assistance can be provided by any suitable number of relays (not shown) or other devices. 
         [0050]    Fluid can enter the sensor housing  60  through an opening  66  located anywhere on the housing&#39;s surface (here, its bottom surface) and come into contact with a pressure sensing surface  68  of the sensor  62 . The sensor  62  is typically hermetically sealed to the motherboard such that fluid entering the opening  66  cannot infiltrate and affect operation of the sensor  62  except at the pressure sensing surface  68 . The sensor  62  can measure the pressure of fluid coming into contact with the pressure sensing surface  68  as fluid flows in and out of the opening  66 . For example, the pressure sensing surface  68  can include a diaphragm having a deformable surface such that when fluid flows through the opening  66 , the fluid impacts the surface of the diaphragm, causing the surface to mechanically displace. The mechanical displacement of the diaphragm can be converted to an electrical signal by a variable resistance circuit including a pair of variable resistance, silicon strain gauges. One strain gauge can be attached to a center portion of diaphragm to measure the displacement of the diaphragm, while the second, matched strain gauge can be attached near the outer edge of diaphragm. The strain gauges can be attached to the diaphragm with adhesives or can be diffused into the diaphragm structure. As fluid pressure within the gastric coil  20  fluctuates, the surface of the diaphragm can deform up or down, thereby producing a resistance change in the center strain gauge. 
         [0051]    One embodiment of a variable resistance circuit for the sensor  62  is shown in  FIG. 6 . The circuit includes first and second strain gauges  96 ,  98  that form the top two resistance elements of a half-compensated, Wheatstone bridge circuit  100 . As the first strain gauge  96  reacts to the mechanical displacements of the sensor&#39;s diaphragm, the changing resistance of the first gauge  96  changes the potential across the top portion of the bridge circuit  100 . The second strain gauge  98  is matched to the first strain gauge  96  and athermalizes the Wheatstone bridge circuit  100 . First and second differential amplifiers  102 ,  104  are connected to the bridge circuit  100  to measure the change in potential within the bridge circuit  100  due to the variable resistance strain gauges  96 ,  98 . In particular, the first differential amplifier  102  measures the voltage across the entire bridge circuit  100 , while the second differential amplifier  104  measures the differential voltage across the strain gauge half of bridge circuit  100 . The greater the differential between the strain gauge voltages, for a fixed voltage across the bridge, the greater the pressure difference. Output signals from the differential amplifiers  102 ,  104  can be applied to the microcontroller  65  integrated into the circuit board  64 , and the microcontroller  65  can transmit the measured pressure data to a device external to the patient. If desired, a fully compensated Wheatstone bridge circuit can also be used to increase the sensitivity and accuracy of the pressure sensor  62 . In a fully compensated bridge circuit, four strain gauges are attached to the surface of diaphragm rather than only two strain gauges. 
         [0052]      FIG. 7  illustrates one embodiment of components included in the internal and external portions  10   a ,  10   b  of the stomach distension system  10 . As shown in  FIG. 7 , the external portion  10   b  includes a primary TET coil  130  for transmitting a power signal  132  to the internal portion  10   a . A telemetry coil  144  is also included for transmitting data signals to the internal portion  10   a . The primary TET coil  130  and the telemetry coil  144  combine to form an antenna, e.g., the reading device  70 . The external portion  10   b , e.g., the control box  90 , includes a TET drive circuit  134  for controlling the application of power to the primary TET coil  130 . The TET drive circuit  134  is controlled by a microprocessor  136  having an associated memory  138 . A graphical user interface  140  is connected to the microprocessor  136  for inputting patient information and displaying and/or printing data and physician instructions. Through the user interface  140 , a user such as the patient or a clinician can transmit an adjustment request to the physician and also enter reasons for the request. Additionally, the user interface  140  can enable the patient to read and respond to instructions from the physician and/or pressure measurement alerts, as discussed further below. 
         [0053]    The external portion  10   b  also includes a primary telemetry transceiver  142  for transmitting interrogation commands to and receiving response data, including sensed pressure data, from the implanted microcontroller  65 . The primary transceiver  142  is electrically connected to the microprocessor  136  for inputting and receiving command and data signals. The primary transceiver  142  drives the telemetry coil  144  to resonate at a selected RF communication frequency. The resonating circuit can generate a downlink alternating magnetic field  146  that transmits command data to the microcontroller  65 . Alternatively, the transceiver  142  can receive telemetry signals transmitted from a secondary TET/telemetry coil  114  in the internal portion  10   a . The received data can be stored in the memory  138  associated with the microprocessor  136 . A power supply  150  can supply energy to the control box  90  in order to power element(s) in the internal portion  10   a . An ambient pressure sensor  152  is connected to microprocessor  136 . The microprocessor  136  can use a signal from the ambient pressure sensor  152  to adjust the received pressure measurements for variations in atmospheric pressure due to, for example, variations in barometric conditions or altitude, in order to increase the accuracy of pressure measurements. 
         [0054]      FIG. 7  also illustrates components of the internal portion  10   a , which in this embodiment are included in the sensor housing  60  (e.g., on the circuit board  64 ). As shown in  FIG. 7 , the secondary TET/telemetry coil  114  receives the power/communication signal  132  from the external antenna. The secondary coil  114  forms a tuned tank circuit that is inductively coupled with either the primary TET coil  130  to power the implant or the primary telemetry coil  144  to receive and transmit data. A telemetry transceiver  158  controls data exchange with the secondary coil  114 . Additionally, the internal portion  10   a  includes a rectifier/power regulator  160 , the microcontroller  65 , a memory  162  associated with the microcontroller  65 , a temperature sensor  112 , the pressure sensor  62 , and a signal conditioning circuit  164 . The implanted components can transmit pressure measurements (with or without adjustments due to temperature, etc.) from the sensor  62  to the control box  90  via the antenna (the primary TET coil  130  and the telemetry coil  144 ). Pressure measurements can be stored in the memory  138 , adjusted for ambient pressure, shown on a display on the control box  90 , and/or transmitted, possibly in real time, to a remote monitoring station at a location remote from the patient. 
         [0055]    As illustrated in a process shown in  FIG. 8 , the sensor housing  60  can generally sense pressure within the gastric coil  20 , locally store the sensed pressure data (e.g., at the memory  162 ), and communicate at least a portion of the sensed pressure data to an external device such as the control box  90  via the reading device  70 . While the pressure sensor  62  can communicate all pressure data it senses to the reading device  70 , communicating only a selected portion of the pressure data (e.g., a portion less than the entirety of the sensed pressure data) can use less power, require less physical and/or electronic storage space in the sensor housing  60 , and/or reduce costs. 
         [0056]    While the process shown in  FIG. 8  is discussed with relation to the elements included in  FIGS. 1A-7 , a person skilled in the art will appreciate that the process can be modified to include more or fewer elements, reorganized or not, and can be performed in the system  10  or in another, similar system having other, similar elements. For example, the microcontroller  65  processes instructions in this embodiment, but any processor configured to process instructions for a system (e.g., a central processing unit, a microprocessor, a digital signal processing unit, application specific integrated circuits (ASICs), a state machine, an analog computer, an optical or photonic computer, logic circuitry, etc.) can be used. Furthermore, the sensor  62  in this illustrated embodiment measures fluid pressure, but any sensed pressure data related to the coil  20  can be handled as discussed herein. 
         [0057]    In use, the sensor housing  60  can sense  400  a pressure of fluid disposed within the system  20  using the sensor  62 . The sensor  62  can transmit measured signals to the signal conditioning circuit  164 , which can amplify the signals before the signal conditioning circuit  164  transmits  402  the measured pressure data to the microcontroller  65 . Alternatively, in some embodiments, the sensor  62  can directly transmit signals to the microcontroller  65 . In this embodiment, the pressure sensor  62  provides pressure data at an update rate of approximately 20 Hz. Such a rate can provide a telemetry/TET mode cycle completion at approximately every 50 ms. For example, the TET/telemetry coil  114  can provide TET for the sensor housing  60  for approximately 45 ms to power the sensor housing  60  and then provide telemetry of pressure data for approximately 5 ms. Of course, any other switching topology can be used. It will also be appreciated that switching between TET and telemetry may be unnecessary. For example, the sensor housing  60  can be active, such that TET is not required. As another example, a second coil (not shown) can be added to the sensor housing  60 , with one of the coils in the sensor housing  60  being dedicated to TET and the other to telemetry. Still other alternatives and variations will be apparent to those of ordinary skill in the art. 
         [0058]    Having received sensed pressure data, the microcontroller  65  can determine  404  whether to store  412  the data, e.g., in the memory  162 . Any type of memory can be used for the memory  162 , including but not limited to one or more of volatile (e.g., SRAM, etc.), non-volatile (e.g., flash, hard drive, etc.), or other memory. Determining whether to store the data allows the microcontroller  65  to analyze the data and potentially discard at least a portion of the data before storing it, thereby using less of the storage space available in the memory  162 . The microcontroller  65  can, however, be configured to store  412  all sensed pressure data and thus may not make such a determination and instead proceed to evaluating  406  whether any of the data triggers an alert, as further discussed below. (In such a configuration, it may be more power efficient to store raw (unprocessed) data from the pressure sensor  62  and process the raw data via an external reading device.) Furthermore, the memory  162  can be used to store pre-selected information or pre-selected types of information. For example, the memory  162  can store maximum, minimum, and/or baseline, pressure measurements, pressure profiles, pressure trends, and/or any other information. Other information suitable for storing in the memory  162  will be appreciated by those skilled in the art. 
         [0059]    The microcontroller  65  can analyze the data in a variety of ways in determining whether to store it. Typically, the microcontroller  65  analyzes a sequence of pressure data values measured over a period of time rather than analyzing every discrete pressure measurement, thereby allowing analysis of pressure trends over time and saving processing resources by not necessarily having to continually analyze incoming data. The microcontroller  65  can, however, evaluate individual pressure data measurements (and/or a range of data) for invalid data and determine to discard any invalid data. Generally, in determining whether to store data, the microcontroller  65  considers a variation of pressure data from a nominal pressure, or resting pressure, within the coil  20 . The nominal pressure is typically programmed into the microcontroller  65  by a physician based on historical coil performance in the patient or, particularly for recently implanted coils, in a typical patient. If the measured pressure data exceeds the nominal pressure, then the data indicates pressure variation in the system  10  and hence likely includes potentially beneficial information for analytical, diagnostic, and/or other purposes. If the pressure data substantially equals the nominal pressure, then the data is not likely indicative of a potentially significant event for analysis purposes, e.g., a change in coil pressure due to patient activity such as eating or drinking. The microcontroller  65  can discard any such substantially nominal data. Discarding data can include not storing the data or storing a representation of the data, e.g., storing a specific set of digits (e.g., “888,” “999,” “000,” etc.) or one or more alphabetic characters. Different representations of data can be used to indicate measurement of a different types of data, e.g., substantially nominal data, data outside a defined pressure range, etc. Although, in some embodiments, the microcontroller  65  can store  412  even nominal pressure data in the memory  162  to maintain a complete historical record of pressure measurements. Furthermore, the microcontroller  65  can store  412  all sensed pressure data it receives in the memory  162  and subsequently determine whether to keep or discard it, e.g., store all data and analyze it every “X” minutes and/or upon signal from an external device. 
         [0060]      FIGS. 9 and 10  show example sequences of pressure data that the microcontroller  65  can receive from the sensor  62 . In each of  FIGS. 9 and 10 , a plot shows sensed pressure data versus time for a twenty-four hour period. The plot in  FIG. 9  includes four periods  407   a ,  407   b ,  407   c ,  407   d  of substantially nominal pressure at a nominal pressure level  409 . The nominal pressure level  409  shown in the plot is an example only; the nominal pressure value can be any value or range of values. Furthermore, the nominal pressure value for a patient can change over time, e.g., as the patient loses weight. The microcontroller  65  can compare the pressure data from this twenty-four hour period with the nominal pressure  409  and determine to discard data from the nominal pressure periods  407   a ,  407   b ,  407   c ,  407   d  (e.g., never store it in the memory  162  or delete it from the memory  162 ) and only store  412  the remaining, selected portion of pressure data. In some instances, the microcontroller  65  can determine to discard pressure data that exceeds the nominal pressure  409 . For example, the microcontroller  65  can discard pressure data except for data obtained during two of three meals the patient ate during the day, e.g., discard pressure data measured during the four periods  407   a ,  407   b ,  407   c ,  407   d  and during a breakfast period  411  and store  412  the remaining, selected pressure data, corresponding to lunch and dinner periods  413 ,  415 . Pressure data can be determined to be related to a particular meal based on one or more factors considered by the microcontroller  65 , such as a combination of a time of day when the sensor  62  measured the data and a duration of pressure values above the nominal level  409 . 
         [0061]    The microcontroller  65  can also determine to discard pressure data related to one or more physiologic events, as illustrated in  FIG. 10 . Non-limiting examples of physiologic events include supra events (e.g., coughing, vomiting, wretching, etc.) and normal events (heartbeats, breathing, talking, etc.). Physiologic events can result in measured pressure data that significantly differs from an expected level in magnitude, duration, occurrence (e.g., an unexpected time of day, such as midnight), and/or frequency from established patterns of patient eating. The microcontroller  65  can determine to retain pressure data by analyzing the data for such a significant difference, such as by determining if any of the obtained pressure data includes a value above a pre-programmed threshold value typically not exceeded except in response to a physiologic event. The microcontroller  65  can also or instead determine if any of the obtained pressure data includes a value within a defined range of pressure values. Depending on the defined range, which can in some embodiments be defined at an upper and/or lower limit by an immediately preceding pressure data value or by pressure values corresponding to a particular time of day, the microcontroller  65  can determine to discard data within the range (e.g., if the range reflects pressure readings of an expected frequency and magnitude caused by a normal event) or to retain data within the range (e.g., if the range includes any positive pressure values up to a threshold value typically not exceeded except by a physiologic event). As an example, the plot in  FIG. 10  includes pressure data  413  indicative of a super-physiologic event, pressure data  415  indicative of a normal event, and actual gastric coil pressure data  417 . The microcontroller  65  can discard the super-physiologic event data  413  and the normal event data  415  using one or more programmed algorithms as described above. 
         [0062]    The microcontroller  65  can also determine  406  whether any data triggers an alert. If the microcontroller  65  determines that any pressure data falls outside a defined range of pressure values and/or is more or less than a threshold value, then the microcontroller  65  can provide  408  an alert to a physician, the patient, and/or to any number of other people because such outlying pressure data can indicate a possible problem such as coil bladder leakage, coil over-extension, recurrent wretching, coil slippage, erosion, etc. The microcontroller  65  can provide the alert by, for example, communicating a signal to an external device (e.g., the control box  90 ) indicating the potentially problematic sensed pressure data and triggering notice of the alert. An alert can include any one or more of the following: an e-mail, a phone call, a text message, an audible signal, a mechanical vibration, a light or other visual display, a tactile display, a message displayed on an external device, or any other type of alert. Different alert patterns (e.g., varying audio signals, varying vibration patterns, etc.) can be used to signify different conditions. Two or more alerts can be provided to multiple people under similar conditions, although alerts may not be provided simultaneously to multiple people or be provided to anyone at all. The conditions for and/or the type of an alert can also vary relative to the recipient of the alert. For example, with respect to alerts for physicians or other medical personnel, such alerts may be limited to those provided upon a super-event indicating that some component of the internal portion  10   a  has structurally failed (e.g., a kink in catheter  50 , a leak in the coil bladder  24 , etc.). With respect to alerts for patients, such alerts may be limited to patient activity such as those provided upon an indication that the patient is eating too much, or eating too quickly. A variety of other conditions under which alerts can be directed to a physician, a patient, and/or another person will be understood by those skilled in the art. Other suitable processes for detecting alert triggers, as well as ways in which the alerts can be provided and the timing of providing the alerts (e.g., immediately, on a regular schedule such as every day or every hour, after detection of a certain milestone or pattern of data, etc.), will be appreciated by those skilled in the art. 
         [0063]    The microcontroller  65  can optionally compress  410  data prior to storing  412  data in the memory  162 . Such compression can reduce the amount of memory space required to store data in the internal portion  10   a  (and subsequently in the external portion  10   b ), reduce the number of microcontroller accesses to the memory  162  (thereby saving power), reduce the amount of time and/or power required to communicate data from the sensor housing  60  to an external device, and allow more data to be locally stored prior to communicating the data to an external device. While pressure data is shown in  FIG. 8  as being compressed following a determination of a selected portion of data to store in the memory  162 , if any, the microcontroller  65  can compress data before making such as determination. For example, as mentioned above, the microcontroller  65  can store  412  pressure data prior to making such a determination (possibly subsequently retrieving the data for analysis). As another example, the microcontroller  65  may not be configured to perform such determining analysis and may store  412  all data for communication to an external device. 
         [0064]    The microcontroller  65  can compress data using any one or more lossless and/or lossy compression techniques. Non-limiting examples of lossless compression techniques include recording difference values (instead of absolute values), reducing the sensor&#39;s data sampling rate (which can include reducing the sensor&#39;s data sampling rate to zero) during a determined period (e.g., a period of quiescent pressure, after a certain period of data-gathering time, etc.), run-length coding, Huffman coding, and other types of lossless compression. Non-limiting examples of lossy compression includes using a quantization table (e.g., sparse quantization) and other types of lossy compression. Storing difference values instead of absolute values can be effective compression if, typically at the beginning of pressure measuring and at regular intervals, the microcontroller  65  stores an absolute value in the memory  162  that can serve as a baseline in reconstructing the originally sensed data. Sensed pressure values are often near the values of their neighbors, so differences from a baseline are often likely to be small, if not zero. The microcontroller  65  can compress difference values for storage using a compression technique, such as encoding difference values into the shortest code symbols in Huffman coding. 
         [0065]    Data stored in the memory  162  can be communicated  414  to an external device. In some embodiments, the microcontroller  65  continually communicates  414  data (via the telemetry transceiver  158  and the secondary coil  114 ), and the data is only received when an appropriate receiving device, such as the antenna (the primary TET coil  130  and the telemetry coil  144 ), moves into sufficient proximity of it. In some embodiments, a download of data from the memory  162  can be triggered  416  when an external device (e.g., the reading device  70 ) telemetrically provides power to the sensor housing, e.g., when the external device is moved in proximity of the sensor housing  60 . The external device can be mobile (e.g., a wand or hand-held unit that can be waved or otherwise placed in proximity of the sensor housing  60 ) or stationary (e.g., a bedside, desk-mounted, or car-mounted box that the patient can move near). Telemetrically providing power to the sensor housing  60  can save power in the internal portion  10   a  because download communication power is supplied by the external portion  10   b.    
         [0066]    The external device can be configured to store  418  data received from the sensor housing  60 . The external device can be further configured communicate  420  the data to another external device, such as a base unit at a location remote from the patient. The external device (typically, the control box  90  or other device having a capability to display or otherwise provide an alert) can detect  422  if the internal portion  10   a  communicated a signal indicating an alert and provide  424  an alert as appropriate (e.g., displaying a warning notice, sending an e-mail message, etc.). 
         [0067]    As mentioned above, a pressure history (e.g., pressure data gathered by the sensor  62 ) can be uploaded to the control box  90  (and/or other units located local or remote to the patient) to allow a person to physically evaluate and/or the control box  90  to electronically evaluate the patient&#39;s treatment and/or performance of elements included in the internal portion  10   a  over a designated time period.  FIG. 11  illustrates an embodiment of an external device, a data logger  270 , that can be used as an external storage mechanism to store pressure measurements over a period of time. The data logger  270  can function as a removably attached data reading device  70 , mentioned above. In this example, the data logger  270  includes a wearable pack external to the patient worn on a belt  274  and positioned over or within communication range of the region under which the sensor housing  60  is implanted within the patient. Alternatively, the data logger  270  can be worn about the patient&#39;s neck, as shown by a device  270 ′, such as when the injection port  30  is implanted in the patient&#39;s stomach and the port  30  includes the pressure sensing device. In another embodiment, the data logger  270  is also implanted within the patient. 
         [0068]    As shown in  FIG. 11 , the data logger  270  includes a TET coil  285  and a telemetry coil  272  which can be worn by the patient so as to lie adjacent to the internal portion  10   a . The TET coil  285  can provide power to the implant, while the telemetry coil  272  can interrogate the implant and can receive data signals, including pressure measurements, through the secondary telemetry coil  114  in the implanted portion  10   a . In another embodiment, the TET coil  285  and the telemetry coil  272  can be consolidated into a single coil and alternate between TET and telemetry functions at any suitable rate for any suitable durations. 
         [0069]    The pressure within the coil  20  can be repeatedly sensed and transmitted to the data logger  270  at an update rate sufficient to measure peristaltic pulses against the coil  20 . Typically, this update rate is in the range of 10-20 pressure measurements per second, but any update range can be used. The data logger  270  is typically worn during waking periods to record pressure variations during the patient&#39;s meals and daily routines. At the end of the day, or another set time period, the data logger  270  can be removed and recorded pressure data downloaded to the external memory  138 . The pressure history can be uploaded from the memory  138  to a remote unit over one or more communication links during a subsequent communication session. Alternatively, pressure data can be directly uploaded from the data logger  270  to a remote unit using one or more communication links. A communication link can include any single or combination of two or more data transmission media including web-based systems utilizing high-speed cable or dial-up connections, public telephone lines, wireless RF networks, Bluetooth, ultrawideband (UWB), satellite, T1 lines or any other type of communication media suitable for transmitting data between remote locations. The data logger  270  can be configured to dock into another device, e.g., a docking station, that is configured to receive data communication from the data logger  270  and transmit the received data to a remote unit. 
         [0070]      FIG. 12  shows the data logger  270  in greater detail. As shown in  FIG. 12 , the data logger  270  includes a microprocessor  276  for controlling telemetry communications with the internal portion  10   a . The microprocessor  276  is connected to a memory  280  for, at least, storing pressure measurements from the internal portion  10   a . In this embodiment, the memory  280  includes forty MB of Non-Volatile EEPROM or FLASH memory and is configured to store about one hundred hours of time stamped pressure data, but any other type of storage can be used, and the memory  280  can store any amount of and any type of data. By way of non-limiting example, any other type of volatile memory or any type of non-volatile memory can be used, including but not limited to flash memory, hard drive memory, etc. While the data logger  270  in this example is operational, pressure can be read and stored in the memory  280  at a designated data rate controlled by the microprocessor  276 . 
         [0071]    The microprocessor  276  can be energized by a power supply  282 . In one embodiment, the power supply  282  includes a rechargeable cell (not shown), such as a rechargeable battery. In some embodiments, the rechargeable cell is removable and can be recharged using a recharging unit and replaced with another rechargeable cell while the spent cell is recharging. In other embodiments, the rechargeable cell can be recharged by plugging a recharging adapter into the data logger  270  and a wall unit. In yet another embodiment, the rechargeable cell can be recharged wirelessly by a wireless recharging unit. In still another embodiment, the power supply  282  includes an ultra capacitor, which can also be recharged. Of course, any other type of power supply can be used. 
         [0072]    To record pressure, the microprocessor  276  can initially transmit a power signal to the internal portion  10   a  via a TET drive circuit  283  and the TET coil  285 . After transmitting the power signal, the microprocessor  276  can transmit an interrogation signal to the internal portion  10   a  via a telemetry transceiver  284  and the telemetry coil  272 . The interrogation signal can be intercepted by the telemetry coil  114  and transmitted to the microcontroller  65 . The microcontroller  65  can send a responsive, optionally-temperature-adjusted pressure reading from the sensor  62  via the transceiver  158  and the secondary telemetry coil  114 . The pressure reading can be received through the telemetry coil  272  and directed by the transceiver  284  to the microprocessor  276 . The microprocessor  276  can store the pressure measurement and initiate the next interrogation request. If applicable, the microprocessor  276  can also respond to an alert identified by the microcontroller  65 , such as with a visual alert (e.g., flashing a light on the data logger  270 , displaying a message on a user interface  292 , etc.) and/or with an audible alert. The user interface  292  can include any number and types of features, including but not limited to a speaker, an LED, an LCD display, an on/off switch, etc. In some embodiments, the user interface  292  is configured to provide only output to the patient and does not permit the patient to provide input to the data logger  270 . The user interface  292  thus includes an LED, which when lit shows that the power supply  282  is sufficiently charged and another, differently colored LED to show when the power supply  282  needs to be recharged, although such power indicators can be shown using any type and any combination of indicators such as one light that illuminates upon low power charge, an audible alert, an email alert, etc. In other embodiments, the user interface  292  can allow the patient to provide input to the data logger  270  and can accordingly include any suitable components and features. 
         [0073]    When finished measuring and recording pressure, the data logger  270  can be removed from the patient and/or from the belt  274  and the recorded pressure data downloaded to the control box  90  (and/or to any other external device). The data logger  270  can include a modem  286  for transmitting sensed pressure data directly to a remote base unit using a communication link. For example, the patient can connect the modem  286  to a telephone line (or other communication link), dial the physician&#39;s modem (if necessary), and select a “send” button on the user interface  292 . Once connected, the microprocessor  276  can transmit stored pressure history through the phone line to a microprocessor included in the remote unit. Alternatively, the data logger  270  can include a USB port  290  for connecting the logger  270  to the control box  90 . The logger USB port  290  can be connected to a USB port included on the control box  90  and the “send” switch activated to download pressure data to the memory  138  in the control box  90 . After pressure data is downloaded, the logger  270  can be turned off through the user interface  292  or reset and placed back on the patient and/or the belt  274  for continued pressure measurement. 
         [0074]    An alternate embodiment of a data logging system  300  is shown in  FIG. 13 . In this example, the data logging system  300  includes a coil head  354  and a data logger  370 . The coil head  354  and the data logger  370  are in communication via a detachable cable  356 . Any one or more suitable alternative communication links can be used in the place of the cable  356 , including but not limited to a wireless transmitter/receiver system. In the illustrated embodiment, the coil head  354  is worn around the neck of the patient and is positioned generally over the injection port  30  and within communication range of the sensor housing  60 . The data logger  370  is worn on the belt  274  about the patient&#39;s waist. Of course, these respective locations are merely exemplary, and either or both the coil head  354  and the data logger  370  can be positioned elsewhere. By way of non-limiting example, when the injection port  30  is implanted in the patient&#39;s abdomen, the coil head  354  can be worn on the belt  274 . The coil head  354  and the data logger  370  are represented as simple blocks in  FIG. 13  for illustrative purposes only, and either of the coil head  354  or the data logger  370  can be provided in a variety of shapes, sizes, and configurations. 
         [0075]    Exemplary components of the data logging system  300  are shown in  FIG. 14 . As shown, the data logger  370  includes the microprocessor  276 , the memory  280 , the power supply  282 , the USB port  290 , and the user interface  292 . The coil head  354  includes the TET drive circuit  283 , the telemetry transceiver  284 , the TET coil  285 , and the telemetry coil  272 . The TET drive circuit  283  is configured to receive power from the power supply  282  via the cable  356 . The TET drive circuit  283  is further configured to receive signals from the microprocessor  276  via the cable  356 . The telemetry transceiver  284  is configured to receive signals from the microprocessor  276  and transmit signals to the microprocessor  276 , via the cable  356 . In another embodiment, the telemetry transceiver  284  is configured to only transmit signals to the microprocessor  276 . The above discussion of such components with reference to  FIG. 12  can also be applied to the components shown in  FIG. 14 . In the embodiment illustrated in  FIG. 14 , the coil head  354  and the data logger  370  can be viewed as a separation of components including the data logger  270  (described above) into two physically separate units. It will be appreciated by a person skilled in the art that any of the components shown in  FIG. 14 , as well as their relationships, functions, etc., can be varied in any suitable way. 
         [0076]    In the present example, the coil head  354  is configured similar to and functions in a manner similar to the antenna (the primary TET coil  130  and the telemetry coil  144 ) described above. The TET coil  285  of coil head  354  is configured to provide power to the injection port  30 . Of course, to the extent that any other devices (e.g., a pump, etc.) are implanted in the patient that are configured to receive power from the TET coil  285 , the TET coil  285  can also provide power to such devices. Power provided by the TET coil  285  can be provided to the TET coil  285  by and regulated by the TET drive circuit  285 , which can itself receive power from the power supply  282  via the cable  356 . Such power provided to the TET drive circuit  283  can be regulated by the microprocessor  276  via the cable  356 . In addition, or in the alternative, the microprocessor  276  can regulate the manner in which the TET drive circuit  285  provides power to the TET coil  285 . While the present example contemplates the use of RF signaling through the TET coil  285 , any other type of powering technique, as well as alternative power communicators, can be used. Other suitable configurations and relationships between these components, as well as alternative ways in which they may operate, will be appreciated by those skilled in the art. 
         [0077]    The telemetry coil  272  of the coil head  354  is configured to receive signals from the coil  114 , including signals indicative of the pressure within the implanted coil system (e.g., pressure of fluid within the injection port  30 , within the catheter  50 , and/or within the adjustable coil  20 , pressure obtained using the pressure sensor  62 , etc.) and signals indicative of temperature. The telemetry coil  272  can also receive any other type of signal representing any other type of information from any other source. Signals received by the telemetry coil  272  can be communicated to the telemetry transceiver  284 , which can communicate such signals to the microprocessor  276  via the cable  356 . The telemetry transceiver  284  can perform any appropriate translation or processing of signals received from the telemetry coil  272  before communicating signals to the microprocessor  276 . Other suitable configurations and relationships between these components, as well as alternative ways in which they may operate, will be appreciated by those skilled in the art. It will also be appreciated that components may be combined. By way of non-limiting example, the TET coil  285  and the telemetry coil  272  can be consolidated into a single coil and alternate between TET and telemetry functions at any suitable rate for any suitable durations. In addition, while the present example contemplates the use of RF signaling through the telemetry coil  272 , it will be appreciated that any other type of communication technique (e.g., ultrasonic, magnetic, RF, light, inductive, etc.) can be used alone or in any combination, as well as alternative communicators other than a coil, can be used. Furthermore, different data handling can be more beneficial to a given communication technique, and given a particular communication technique, appropriate data handling can be selected. 
         [0078]    In one exemplary use, the patient wears the coil head  354  and the data logger  370  throughout the day to record pressure measurements in the memory  280 . At night, the patient can decouple the data logger  370  from the coil head  354  and couple the data logger  370  with a docking station, e.g., the control box  90 . While the data logger  370  and the control box  90  are coupled, the control box  90  can transmit data received from the data logger  370  to a remote unit. To the extent that the power supply  282  includes a rechargeable cell, the control box  90  can recharge the cell while the data logger  370  is coupled with the control box  90 . However, a patient need not necessarily decouple the data logger  370  from the coil head  354  in order to couple the data logger  370  with the control box  90 . Moreover, pressure measurements can be recorded in the memory  280  during the night in addition to or as an alternative to recording such measurements during the day, and pressure measurements can be recorded twenty-four hours a day. In that way, timing of pressure measurement taking and recordation need not be limited to the daytime only. 
         [0079]    As described above, the data logger  370  can receive, store, and communicate data relating to pressure within the distension system. However, the data logger  370  can receive, store, and/or communicate a variety of other types of data. By way of non-limiting example, the data logger  370  can also receive, process, store, and/or communicate data relating to temperature, EKG measurements, eating frequency of the patient, the size of meals eaten by the patient, the amount of walking done by the patient, etc. It will therefore be appreciated by those skilled in the art that the data logger  370  can be configured to process received data to create additional data for communicating to the control box  90 . For example, the data logger  370  can process pressure data obtained via the coil head  354  to create data indicative of the eating frequency of the patient. It will also be appreciated by those skilled in the art that the data logger  370  can include additional components to obtain non-pressure data. For example, the data logger  370  can include a pedometer or accelerometer (not shown) to obtain data relating to the amount of walking done by the patient. Data obtained by such additional components can be stored in the memory  280  and communicated to the control box  90  in a manner similar to pressure data. The data logger  370  can also include components for obtaining data to be factored in with internal pressure measurements to account for effects of various conditions on the pressure. For example, the data logger  370  can include a barometer for measuring atmospheric pressure. In some embodiments, the data logger  370  includes an inclinometer or similar device to determine the angle at which the patient is oriented (e.g., standing, lying down, etc.), which can be factored into pressure data to account for hydrostatic pressure effects caused by a patient&#39;s orientation. Alternatively, an inclinometer or other device for obtaining non-pressure data can be physically separate from the data logger  370  (e.g., implanted). Still other types of data, ways in which such data may be obtained, and ways in which such data may be used will be appreciated by those skilled in the art. 
         [0080]    It will also be appreciated by those skilled in the art that one or more embodiments described herein can enable health care providers or others to use pressure data as a feedback mechanism to identify, train, and/or prescribe dietary advice to a patient. Such a feedback mechanism can provide data or otherwise be used in multiple ways. For example, pressure feedback can be obtained when a patient swallows a particular food portion, and based on such pressure feedback, the patient can be advised or taught to eat smaller portions, larger portions, or portions equal to the portion tested. Of course, a food portion so prescribed can be tested by evaluating pressure feedback obtained when the patient swallows the prescribed food portion, such that a food portion prescription may be refined through reiteration. As another example, a patient can test desired foods for appropriateness based on pressure feedback together with portion size and/or based on any other parameters. It will also be appreciated by those skilled in the art that continuous pressure data monitoring can be used locally and/or remotely to enable portion size monitoring, food consistency monitoring (e.g., liquids vs. solids), eating frequency, and/or other patient activities. 
         [0081]    While embodiments described above include the use of the pressure sensor  62  within the sensor housing  60  removably joined to the catheter  50 , a pressure sensor can be located elsewhere within a patient. For example, the pressure sensor  62  could be included in the port housing  30 . In another embodiment, shown in  FIG. 15 , a pressure sensor  500  can be located within a gastric coil  502 , such as in an inflatable portion of gastric coil  502 . To the extent that the gastric coil  502  includes a resilient portion and a non-resilient portion, the pressure sensor  500  can be secured to either or neither of the resilient portion or non-resilient portion. In any case, the pressure sensor  500  can sense and communicate fluid pressure within the gastric coil  502  before, during, and after fluid is added to or withdrawn from gastric coil  502  via an injection port  501  and a catheter  503 . The pressure sensor  500  can be used when a pump (not shown) or any other device is used to adjust pressure within the gastric coil  502 . 
         [0082]    Alternatively, as shown in  FIG. 16 , a pressure sensor  504  can be located within a catheter  506  positioned between a gastric coil  508  and a port  507 , pump, reservoir, or other device in fluid communication with the catheter  506 . As another variation, an example of which is shown in  FIG. 17 , a pressure sensor  509  can be fixedly secured in-line with a catheter  506 , while not residing within catheter  506 . 
         [0083]    Yet another variation is shown in  FIG. 18 , which illustrates a catheter  506  having a “T”-shaped intersection  550 . A pressure sensor  504  is disposed in the arm of the “T”-shaped intersection  550  that is perpendicular to the catheter  506  and is in fluid communication with the catheter  506 . In one embodiment, the “T”-shaped intersection  550  is integrally formed with the catheter  506  (as shown). In another embodiment, the “T”-shaped intersection  550  is a separate component joined to the catheter  506  (e.g., using barbed connectors, etc.). Other suitable ways in which the “T”-shaped intersection  550  can be provided will be appreciated by those skilled in the art. Similarly, other ways in which a pressure sensor  504  can be provided within, in-line with, or adjacent to the catheter  506  will be appreciated by those skilled in the art. 
         [0084]    In yet another embodiment (not depicted), a pressure sensor can be located at the interface of an injection port and a catheter, and/or at the interface of a gastric coil and a catheter. Still other suitable locations for a pressure sensor will be appreciated by those skilled in the art, including but not limited to any location in or adjacent to the fluid path of a gastric coil system. In addition, a pressure sensor can be positioned within (e.g., against an inner wall of) a gastric coil, a catheter. Other suitable configurations for housing a pressure sensor within or adjacent to a coil, catheter, or buckle will be appreciated by those skilled in the art. 
         [0085]    In another embodiment, a plurality of pressure sensors can be used. For example, a gastric coil system can include a pressure sensor within a gastric coil in addition to a pressure sensor within a catheter that is in fluid communication with the gastric coil. Such a plurality of pressure sensors can provide an indication of how well fluid pressure is distributed among components of a gastric coil system. Such a plurality of pressure sensors can also provide greater accuracy in pressure readings, reduce the likelihood of catheter obstruction (e.g., pinching) affecting pressure reading, reduce effects of hydrostatic pressure changes from patient movement, and/or provide one or more other results. Any system that includes a plurality of pressure sensors can include a pressure sensor in a port housing and/or a pressure sensor external to the patient (e.g., a pressure sensor in a syringe or in a pressure sensor portion coupled with a syringe), in addition to any of the implanted pressure sensors described above. Furthermore, a device such as an internal or external inclinometer (or a substitute therefore) may be used to determine the angle at which the patient and/or the internal portion is oriented (e.g., standing, lying down, etc.), which may be factored into pressure data sensed by one or more sensors to account for hydrostatic pressure effects caused by a patient&#39;s orientation. Such a factor (or any other factor) may be accounted for prior to or in conjunction with the rendering of a pressure reading. 
         [0086]    A person skilled in the art will appreciate that the present invention has application in conventional endoscopic and open surgical instrumentation as well application in robotic-assisted surgery. 
         [0087]    The devices disclosed herein can be designed to be disposed of after a single use, or they can be designed to be used multiple times. In either case, however, the device can be reconditioned for reuse after at least one use. Reconditioning can include any combination of the steps of disassembly of the device, followed by cleaning or replacement of particular pieces, and subsequent reassembly. In particular, the device can be disassembled, and any number of the particular pieces or parts of the device can be selectively replaced or removed in any combination. Upon cleaning and/or replacement of particular parts, the device can be reassembled for subsequent use either at a reconditioning facility, or by a surgical team immediately prior to a surgical procedure. Those skilled in the art will appreciate that reconditioning of a device can utilize a variety of techniques for disassembly, cleaning/replacement, and reassembly. Use of such techniques, and the resulting reconditioned device, are all within the scope of the present application. 
         [0088]    Preferably, the invention described herein will be processed before surgery. First, a new or used instrument is obtained and if necessary cleaned. The instrument can then be sterilized. In one sterilization technique, the instrument is placed in a closed and sealed container, such as a plastic or TYVEK bag. The container and instrument are then placed in a field of radiation that can penetrate the container, such as gamma radiation, x-rays, or high-energy electrons. The radiation kills bacteria on the instrument and in the container. The sterilized instrument can then be stored in the sterile container. The sealed container keeps the instrument sterile until it is opened in the medical facility. 
         [0089]    It is preferred that device is sterilized. This can be done by any number of ways known to those skilled in the art including beta or gamma radiation, ethylene oxide, steam. 
         [0090]    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. 
         [0091]    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.