Patent Application
20130317412
The present disclosure relates generally to pressure/flow control systems and methods for use in treating a medical condition. In some instances, embodiments of the present disclosure are configured to be part of an IOP control system for the treatment of ophthalmic conditions.
Glaucoma, a group of eye diseases affecting the retina and optic nerve, is one of the leading causes of blindness worldwide. Most forms of glaucoma result when the intraocular pressure (IOP) increases to pressures above normal for prolonged periods of time. IOP can increase due to high resistance to the drainage of the aqueous humor relative to its production. Left untreated, an elevated IOP causes irreversible damage to the optic nerve and retinal fibers resulting in a progressive, permanent loss of vision.
The eye's ciliary body continuously produces aqueous humor, the clear fluid that fills the anterior segment of the eye (the space between the cornea and lens). The aqueous humor flows out of the anterior chamber (the space between the cornea and iris) through the trabecular meshwork and the uveoscleral pathways, both of which contribute to the aqueous drainage system. The delicate balance between the production and drainage of aqueous humor determines the eye's IOP.
One method of treating glaucoma includes implanting a drainage device in a patient's eye. The drainage device allows fluid to flow from the interior chamber of the eye to a drainage site, relieving pressure in the eye and thus lowering TOP. These devices are generally passive devices and do not provide a smart, interactive control of the amount of flow through the drainage tube.
The system and methods disclosed herein overcome one or more of the deficiencies of the prior art.
In one exemplary aspect, the present disclosure is directed to an apparatus for treatment of a medical condition of a patient to provide drainage from a region of a patient to a drainage location. The apparatus may include a memory having a plurality of different selectable treatment algorithms stored therein for treating a medical condition, and may include a processor associated with the memory and configured to execute one of the different treatment algorithms. It also may include a flow system controllable by the processor to regulate drainage of fluid from a body portion having a medical condition, the flow system being controllable according to a selected algorithm of said different selectable treatment algorithms.
In one aspect, the apparatus further comprises an implantable medical device for treating an ocular condition, and the processor is carried on the implantable medical device. In one aspect, each of the plurality of treatment algorithms comprises a plurality of periods of time and target settings corresponding to the periods of time. In one aspect, the pressure/flow system comprises one of a valve and a pump, and the processor controls a setting on said valve or pump.
In another exemplary aspect, the present disclosure is directed to a control system for treatment of an ocular condition of a patient to provide drainage from an anterior chamber of the eye to a drainage location. The control system may include a memory having a plurality of different selectable treatment algorithms stored therein for treating an ocular condition. It also may include a processor associated with the memory and configured to execute one of the different treatment algorithms. A sensor system may be configured to detect a pressure representative of an anterior chamber and configured to detect a pressure representative of atmospheric pressure. The processor may be configured to generate control signals based on a selected one of the different treatment algorithms and on the detected pressures.
In one aspect, the apparatus includes a flow system comprising one of a valve and a pump controllable by the processor to regulate drainage of fluid from an eye, the flow system being controllable according to said selected one of said different selectable treatment algorithms.
In another exemplary aspect, the present disclosure is directed to a method comprising: storing a plurality of selectable treatment algorithms in a memory;
receiving an input selecting one of the selectable treatment algorithms of the plurality of selectable treatment algorithms in a memory; and controlling a flow system to regulate drainage of fluid from a body portion having a medical condition based on the selected one of the selectable treatment algorithms.
In one aspect, the method comprises incrementally adjusting the treatment algorithm. In one aspect, the treatment algorithm includes a target IOP level and or the rate of change from the current setpoint. In another aspect, the treatment algorithm comprises a target open amount of an adjustable valve and or the rate of change from the current setpoint.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory in nature and are intended to provide an understanding of the present disclosure without limiting the scope of the present disclosure. In that regard, additional aspects, features, and advantages of the present disclosure will be apparent to one skilled in the art from the following detailed description.
The accompanying drawings illustrate embodiments of the devices and methods disclosed herein and together with the description, serve to explain the principles of the present disclosure.
For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is intended. Any alterations and further modifications to the described devices, instruments, methods, and any further application of the principles of the present disclosure are fully contemplated as would normally occur to one skilled in the art to which the disclosure relates. In particular, it is fully contemplated that the features, components, and/or steps described with respect to one embodiment may be combined with the features, components, and/or steps described with respect to other embodiments of the present disclosure. For simplicity, in some instances the same reference numbers are used throughout the drawings to refer to the same or like parts.
The present disclosure is directed to a flow control system for treating a medical condition, such as glaucoma. In one aspect, the system controls IOP by regulating fluid drainage through an implant such as a glaucoma drainage device (GDD). The system may control the drainage based on a stored treatment algorithm that provides a desired treatment to a patient to control IOP. In one aspect, the system includes a plurality of stored treatment algorithms and a health care provider may select a desired treatment algorithm from the plurality of stored treatment algorithms based on any number of factors, including surgeon preference, the nature of the treatment, patient characteristics, such as age, size, or overall health, and other factors. Once selected, the treatment algorithm controls the implant to provide a particular treatment profile based on the selected treatment algorithm. Permitting a health care provider to select a particular treatment algorithm may result in better treatment, a more consistent recovery, and ultimately a better patient outcome.
The power source 202 is typically a rechargeable battery, such as a lithium ion or lithium polymer battery, although other types of batteries may be employed. In addition, any other type of power cell is appropriate for power source 202. Power source 202 provides power to the system 200, and more particularly to processor 206. In one embodiment, the power source can be recharged via inductive coupling such as an RFID link or other type of electromagnetic coupling.
The processor 206 is typically an integrated circuit with power, input, and output pins capable of performing logic functions. In various embodiments, processor 206 is a targeted device controller. In such a case, the processor 206 performs specific control functions targeted to a specific device or component, such as the data transmission module 210, the power source 202, the sensing system 204, the flow system 212, or the memory 208. In other embodiments, the processor 206 is a microprocessor. In such a case, processor 206 is programmable so that it can function to control more than one component of the device. In other cases, processor 206 is not a programmable microprocessor, but instead is a special purpose controller configured to control different components that perform different functions.
The memory 208 is typically a semiconductor memory such as RAM, FRAM, or flash memory. The memory 208 interfaces with the processor 206. As such, the processor 206 can write to and read from the memory 208. For example, processor 206 can be configured to read data from the IOP sensor system 204 and write that data to memory 208. In the embodiments shown, a series of treatment algorithms or treatment profiles are stored in the memory 208 for access and execution by the processor. These treatment algorithms may be selected by a health care provider for execution by the processor 208 to treat a medical condition. While only five treatment algorithms are shown for convenience, any number of algorithms may be stored in the control system for selection by a user. In one aspect, the plurality of algorithms are stored on a device separate from the implant for selection, and then the selected algorithm is transferred to implant to control the implant. It should be noted, that the care provider may also be able to design a specific treatment algorithm and load that to the device using a device separate from the implant. The processor 206 is also capable of performing other basic memory functions, such as erasing or overwriting the memory 208, detecting when memory 208 is full, and other common functions associated with managing memory.
The data transmission module 210 may employ any of a number of different types of data transmission. For example, the data transmission module 210 may be an active device such as a radio. Data transmission module 210 may also be a passive device such as the antenna on an RFID tag. In this case, an RFID tag includes memory 208 and data transmission module 210 in the form of an antenna. An RFID reader can then be placed near the system 200 to write data to or read data from memory 208. Therefore, the treatment algorithms may be transmitted to the memory via the data transmission module, along with any selection of or adjustment to the stored treatment algorithms. Other types of data that can be stored in memory 208 and transmitted by data transmission module 210 include, but are not limited to, IOP measurement data, power source data (e.g. low battery, battery defect), speaker data (warning tones, voices), IOP sensor data (IOP readings, problem conditions), time stamp data and the like.
The pressure/flow system 212 may include components or elements that control pressure by regulating the amount of drainage flow. In the example shown, the flow system 212 includes a valve and a pump. The flow system may include any number of valves and any number of pumps, or may not include a pump or may not include a valve. In a preferred embodiment, the flow system 212 is an active system that is responsive to signals from the processor 206 to increase flow, decrease flow, or to maintain a steady flow as a function of pressure. In one embodiment, it does this by maintaining a valve setting at a consistent setting, or increasing or decreasing the amount that the valve is open. The IOP sensor system 204 is described below with reference to
The drainage tube 302 drains aqueous from the anterior chamber 170 of the eye. The flow system 212 regulates the flow of aqueous through the tube 302. In the embodiment shown, the pressure sensor P1 measures the pressure in the tube 302 upstream from the flow system 212 and downstream from the anterior chamber 170. In this manner, pressure sensor P1 measures the pressure in the anterior chamber 170. The expected measurement discrepancy between the true anterior chamber pressure and that measured by P1 when located in a tube downstream of the anterior chamber (even when located between the sclera and the conjunctiva) is very minimal. For example, Poiseuille's law for pipe flow predicts a pressure drop of 0.01 mmHg across a 5-millimeter long tube with a 0.300 millimeter inner diameter for a flow rate of 3 microliters per minute of water.
Pressure sensor P2 is located at the drainage site 306. As such, pressure sensor P2 may be located in a pocket, such as a bleb, that generally contains aqueous or in communication with such a pocket, via a tube for example, and is in a wet location 306. The drainage site 306 may be, for example, in a subconjunctival space, a suprachoroidal space, a subscleral space, a supraciliary space, Schlemm's canal, a collector channel, an episcleral vein, and an uveo-scleral pathway, among other locations in the eye.
In some embodiments, the divider 304 acts as a barrier that separates the pressure sensor P3 from the pressure sensor P2. In some embodiments, the system includes other barriers that separate the sensors P1, P2, and P3. These barriers may be elements of the system itself. In
Generally, IOP is a gauge pressure reading—the difference between the absolute pressure in the eye (as measured by P1) and atmospheric pressure (as measured by P3). Atmospheric pressure, typically about 760 mm Hg, often varies in magnitude by 10 mmHg or more depending on weather conditions or indoor climate control systems. In addition, the effective atmospheric pressure can vary significantly—in excess of 200 mmHg—if a patient goes swimming, hiking, riding in an airplane, etc. Such a variation in atmospheric pressure is significant since IOP is typically in the range of about 15 mm Hg. Thus, for accurate monitoring of IOP, it is desirable to have pressure readings for the anterior chamber (as measured by P1) and atmospheric pressure in the vicinity of the eye (as measured by sensor P3).
Therefore, in one embodiment of the present invention, pressure readings are taken by pressure sensors P1 and P3 simultaneously or nearly simultaneously over time so that the actual TOP can be calculated (as P1−P3 or P1−f(P3), where f(P3) indicates a function of P3). The pressure readings of P1 and P3 can be stored in memory 208 by processor 206. They can later be read from memory so that actual IOP over time can be interpreted by a physician.
Pressure sensors P1, P2, and P3 can be any type of pressure sensors suitable for implantation in the eye. They each may be the same type of pressure sensor, or they may be different types of pressure sensors. For example, pressure sensors P1 and P2 may be the same type of pressure sensor (implanted in the eye), and pressure sensor P3 may be a different type of pressure sensor (in the vicinity of the eye).
In another embodiment of the present invention, pressure readings taken by pressure sensors P1, P2, and P3 can be used to control a device that drains aqueous from the anterior chamber 170.
The drainage tube 302 may be arranged to shunt fluid from the anterior chamber 170 to the drainage location 306, which may be placed at any of numerous locations within the eye. For example, some tubes are arranged to shunt aqueous from the anterior chamber 170 to the subconjunctival space thus forming a bleb under the conjunctiva or alternatively, to the subscleral space thus forming a bleb under the sclera. Other tube designs shunt aqueous from the anterior chamber to the suprachoroidal space, the supraciliary space, the juxta-uveal space, or to the choroid, forming blebs in those respective locations. In other applications, the drainage tube shunts aqueous from the anterior chamber to Schlemm's canal, a collector channel in Schlemm's canal, or any of a number of different blood vessels like an episcleral vein. In some examples, the drainage tube even shunts aqueous from the anterior chamber to outside the conjunctiva. Each of these different anatomical locations to which aqueous is shunted is an example of a drainage location 306. Other examples of a drainage location 306 include, but are not limited to: a subconjunctival space, a suprachoroidal space, a subscleral space, a supraciliary space, Schlemm's canal, a collector channel, an episcleral vein, and an uveo-scleral pathway.
One complication involved with surgery that shunts the anterior chamber 170 to a drainage location 306 is hypotony—a dangerous drop in IOP that can result in severe consequences. Accordingly, it can be desirable to control the rate of aqueous outflow from the anterior chamber 170 to the drainage location 306 so as to prevent hypotony.
In one exemplary aspect, the present disclosure is directed to a system that employs a particular treatment plan, as a stored treatment algorithm, to provide therapeutic treatment to the patient, such as to the eye of the patient. In this exemplary aspect, the treatment algorithms dictate the changes to the implant 300, including changes to the flow system 212, that may occur to regulate the IOP and maintain a desired level. In one aspect, the flow system 212 is controlled to open, close, or throttle flow to optimize efficacy. For example according to one stored treatment algorithm or profile, the flow system 212 may include a valve that is closed during an initial period of time to allow the implantation area to heal. The valve may then be opened or throttled at a later time to control IOP. Using the pressure sensor feedback, the valve state may be manipulated such that IOP is kept constant or allowed to ramp up or down. In one aspect, various control algorithms may be implemented at different times of the day to accommodate synergy with a drug therapy or a patient's diurnal patterns.
During the period of time T1 to T2, the processor 206 controls the flow system 212 to gradually decrease the IOP to target value IOP1. The rate of change from the IOP value in the prior period T0 to T1 to the target IOP1 may be set using the slope-intercept equation y=mx+b, and may vary depending on the equation and the desired change. It should be noted that y=mx+b is a known linear equation and is used here as an example that may be substituted with more complex nonlinear or discontinuous equations to accommodate different needs.
During the period of time T2 to T3, the processor 206 controls the flow system 212 maintain the actual IOP in line with the target value IOP1. It may be do this based on readings from the sensor system 204 including readings received from the sensors P1, P2, and P3. By calculating the IOP based on the sensor readings, and comparing the calculated IOP to the target value IOPI, the IOP control system 200 can determine whether to further control the flow system 212 to increase or decrease flow to maintain the desired IOP. For example, the valves in the flow system 212 may be opened wider or closed more, and a pump may or may not be activated to control the flow and regulate the IOP, depending on the data measured by the sensors.
During the period of time T3 to T4, the flow system 212 is controlled to gradually decrease the IOP to target value IOP2. The rate of change from the IOP value in the prior period T3 to T4 to the target IOP2 may be set using the slope-intercept equation y=mx+b, and may vary depending on the equation and the desired change.
Finally, during the period of time T4 to T5, which may last until the time the implant is surgically removed, the processor 206 controls the flow system 212 to maintain the actual IOP in line with the target value IOP2.
A corresponding flow chart representing control logic of a treatment algorithm is shown in
The method in
In accordance with the treatment algorithm in
Based on this measurement, the processor 206 may adjust a valve set point of the flow system 212 in order to achieve the desired IOP at a step 606. In some treatment algorithms, such as the one disclosed with reference to
At step 608, after the valve set point is modified to maintain the IOP at a desired value, the system 200 initiates a sleep mode for a period of time corresponding to T2-T3 in
In an alternative embodiment, the treatment algorithm controls flow based on settings of the flow system 212 in an open loop configuration where the system relies upon settings of elements of the flow system 212 instead of, in place of, or in addition to, settings based on detected pressure readings as indicative of IOP. In this embodiment, the control system 200 may control flow based on settings of the components, such as a valve setting. One example of such a treatment algorithm is described with reference to
In
During the period of time T2 to T3, the processor makes no additional adjustments to the flow system 212, thereby maintaining the settings for the flow system.
During the period of time T3 to T4, the processor adjusts the flow system 212 further, increasing the drainage capacity of the implant by opening the valve further to permit additional drainage. In this example, the setting during the period of time T3 to T4 is 50% open. Other amounts are contemplated depending on the stored treatment algorithm. During the time period after T4, the valve is maintained at its set position in accordance with the treatment algorithm.
As described above, the implant 300 may store one or more of the treatment algorithms to provide a desired treatment profile for a particular patient. A surgeon may select the desired treatment algorithm based on any number of factors.
In one embodiment, the surgeon may modify the treatment algorithm by increasing the levels of IOP1, IOP2, percentage open, or other amounts. For example, one embodiment of the system allows a surgeon to increase or decrease the time period of T0 to T1 from a default value. Another embodiment permits a surgeon to incrementally shift the treatment algorithm upward or downward along the y-axis in the graphs of
In one example, the treatment algorithm is arranged to operate at a first IOP setting during a morning and to operate at a second IOP setting later in the day. The system may reset at a particular time and run the same program the next day. Accordingly, the treatment algorithm may make daily adjustments based on the time of day, readings from the sensor system 204, or other factors.
As described above, the implant may include any number of treatment algorithms to treat a medical condition. For example, the flow system 212 can be adjusted to maintain a particular IOP (like an IOP of 15 mm Hg). Flow system 212 may be opened at desirable times, such as, for example, more at night than during the day to maintain a particular IOP. In other embodiments, an IOP drop can be controlled by the flow system 212. The flow system 212 can be adjusted to permit a gradual drop in IOP based on readings from pressure sensors P1 and P3. In some embodiments, the physician would be able to set the high/low IOP thresholds wirelessly to meet each patient's specific requirements.
Persons of ordinary skill in the art will appreciate that the embodiments encompassed by the present disclosure are not limited to the particular exemplary embodiments described above. In that regard, although illustrative embodiments have been shown and described, a wide range of modification, change, and substitution is contemplated in the foregoing disclosure. It is understood that such variations may be made to the foregoing without departing from the scope of the present disclosure. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the present disclosure.
