Patent Application
20120234433
In various embodiments, the present invention relates, generally, to implantable drug pump devices, and in particular to systems and methods for refilling such devices.
Medical treatment often requires the administration of a therapeutic agent (e.g., medicament, drugs, etc.) to a particular part of a patient's body. As patients live longer and are more frequently diagnosed with chronic and often debilitating ailments, the result will be an increase in the need to place protein therapeutics, small-molecule drugs and other medications into targeted areas throughout the body. Some maladies, however, are difficult to treat with currently available therapies and/or require administration of drugs to anatomical regions to which access is difficult to achieve.
A patient's eye is a prime example of a difficult-to-reach anatomical region, and many vision-threatening diseases, including retinitis pigmentosa, age-related macular degeneration (AMD), diabetic retinopathy, and glaucoma, are incurable and yet difficult to treat with currently available therapies. For example, oral medications have systemic side effects; topical applications may sting and engender poor compliance; injections require a medical visit, can be painful and risk infection; and sustained-release implants must typically be removed after their supply is exhausted (and generally offer limited ability to change the dose in response to the clinical situation). Another example is cancer, such as breast cancer or meningiomas, where large doses of highly toxic chemotherapies such as rapamycin or irinotecan (CPT-11) are typically administered to the patient intravenously, resulting in numerous undesired side effects outside the targeted area. Yet another example is drug delivery to the knee, where drugs often have difficulty penetrating the avascular cartilage tissue for diseases such as osteoarthritis.
Implantable drug delivery systems, which may have a refillable drug reservoir, cannula and check valve, etc., generally allow for controlled delivery of pharmaceutical solutions to a specified target. As drug within the drug reservoir depletes, the physician can refill the reservoir with, for example, a syringe, via a refill port while leaving the device implanted within the patient's body. This approach can minimize the surgical incision needed for implantation and avoids future or repeated invasive surgery or procedures.
Conventionally, the drug pump is refilled manually using, for example, a handheld syringe. This approach can be both inconvenient and dangerous. It is typically difficult to monitor the pressure in the syringe, and a large pressure may be generated inadvertently particularly when small volumes are involved and the syringe plunger is of small diameter. Excessive pressures can damage the pump and/or cause improper drug expulsion. Additionally, refilling the implantable pump may represent a difficult manual task. For example, the pump's refill port, which is usually located on the pump surface to facilitate post-implantation access, may be inaccessible or inconvenient to access due to the recipient's internal anatomy. This makes the refill procedure uncomfortable for the recipient and, once again, risks damage to the pump. Refilling difficulties are especially acute if the therapeutic procedure involves a multiple-drug administration which requires several cycles of needle insertion and withdrawal as different fluids are removed and injected into the pump, causing stress for both the patient and doctor and creating wear on the refill port.
Consequently, there is a need for a refilling system that can monitor the pressure during drug administration and reduce the insertion frequency into the implanted pump.
In accordance with various embodiments of the invention described herein, a dedicated instrument is used to automatically facilitate a filling or refilling therapeutic procedure via, for example, a self-sealing needle-accessible refill port in an implanted drug pump. The procedure may include, for example, emptying, rinsing, and filling the drug reservoir. An instrument in accordance with the current invention may be configured such that only a single needle insertion in the fluid access refill port is required to direct multiple fluids to the implanted pump. Additionally, the instrument may include a valve, a pressure sensor and/or a flow sensor to detect and control the pressure therein. The automation and/or pressure-control of the refilling process protects pump components (e.g., the refill port or the reservoir) from potential damage and ensures reliable and repeatable drug filling.
Accordingly, in one aspect, the invention pertains to a tool for refilling an implantable pump having at least one reservoir. In various embodiments, the tool includes: (i) multiple independent fluid channels, (ii) a fluid reservoir in fluid communication with a first fluid channel, and (iii) a connector for removably connecting the fluid channels to the at least one reservoir. The tool may include one or more pumps that are fluidly coupled to the fluid channels. The pump(s) may be configured to apply positive pressure to the first fluid channel so as to drive fluid from the fluid reservoir therethrough, and to apply negative pressure to a second fluid channel.
The pump(s) and the independent fluid channels may differ from each other in number. For example, when there are one pump and at least two independent fluid channels, the pump may be configured to generate suction through a first one of the channels and to drive a fluid through a second one of the channels. If there is a third independent fluid channel connected to the pump, the pump may be configured to drive a second fluid through the third fluid channel.
The tool may include a sensor associated with each of the channels for monitoring at least one parameter relating to liquid flowing therethrough. The sensor may be a flow sensor and/or a pressure sensor and the parameter may be a flow rate of the liquid and/or pressure in the channels, respectively.
Additionally, the tool may include governing circuitry for preventing the monitored parameter from exceeding or falling below a predefined level. Two valves that are responsive to the governing circuitry may be used for controlling fluid flow through the first and second fluid channels.
In a second aspect, the invention relates to a tool for refilling an implantable pump having a reservoir. The tool may include a refilling kit and a base unit. The refilling kit may have two independent fluid channels connectable at one end thereof to the reservoir. The base, which is removably connectable to the other ends of the fluid channels, may include at least one pump, a sensor for monitoring at least one parameter relating to flow through the fluid channels, and feedback circuitry for controlling flow through the fluid channels based on the monitored parameter(s).
The refilling kit may be connectable to the reservoir by means, for example, of a needle configured for entering the reservoir. The needle may have separate lumens each fluidly coupled to one of the fluid channels. The tool may further include a locking system that is associated with the refilling kit for preventing injection of an unapproved fluid into the reservoir.
In a third aspect, the invention relates to a method of filling an implantable drug-delivery pump having at least one reservoir. In some embodiments, the method includes the steps of: (i) fluidly coupling multiple independent fluid channels to the reservoir and (ii) operating a single pump to purge the reservoir via a first one of the multiple channels and pump fluid into the purged reservoir via a second one of the multiple fluid channels. The pump may generate suction through the first fluid channel and drives a fluid through the second fluid channel. The purging step may include causing the single pump to pump fluid into the reservoir through a third independent fluid channel and thereafter provide suction to draw the fluid from the reservoir via the first fluid channel.
Reference throughout this specification to “one example,” “an example,” “one embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the example is included in at least one example of the present technology. Thus, the occurrences of the phrases “in one example,” “in an example,” “one embodiment,” or “an embodiment” in various places throughout this specification are not necessarily all referring to the same example. Furthermore, the particular features, structures, routines, steps, or characteristics may be combined in any suitable manner in one or more examples of the technology. The headings provided herein are for convenience only and are not intended to limit or interpret the scope or meaning of the claimed technology.
In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, with an emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the present invention are described with reference to the following drawings, in which:
Refer first to
In some embodiments, as illustrated in
In various embodiments, the refill instrument 200 includes flow sensors 246 and/or pressure sensors 248 to monitor and control the flow rate and/or pressure, respectively, of the fluid injection and suction in each channel 212, 214, 216. For example, flow sensors 246, based upon thermal effects, time-of-flight, and/or pressure, as explained further below, may be employed within the channels to sense the fluidic flow. In one embodiment, flow sensors 246 based on thermal effects use a resistive heater to locally heat the fluid flowing in proximity to the sensors 246. The temperature of the flowing fluid in the channel then provides an indication of the flow rate. For example, time-of-flight flow sensors 246 generate a tracer pulse in the fluid flowing within the channel, and then measure the time that it takes for this pulse to traverse a certain distance. This measured time is defined as the “time of flight” and corresponds to the linear fluid velocity, which may be translated into a volumetric flow rate. In another embodiment, flow sensors 246 utilize pressure sensing and are employed within the fluid channel to measure the pressure therein and, based thereon, to increase or reduce the fluid flow rate through the channels when necessary. The pressure-based flow sensors 246 may function in any of a variety of ways; for example, capacitive, piezoresistive, and piezoelectric implementations, among others known to those of ordinary skill in the art, may all be employed advantageously. In various embodiments, if one or more pressure sensors 248 are placed inside the channels 212, 214, 216, operations of the channels associated pumps 220, 222, 224 may be adjusted to maintain an optimal pressure or pressure range during the filling/refilling process and thus avoid excess pressure, prevent damage to the pumps, and unwanted ejection of drug into the patient.
A critical set of values that define the upper and lower bounds of the safe range of pressure and/or flow rate may be determined before the filling/refilling process. If the pressure and/or flow rates exceed or fall below the set critical values during the filling/refilling procedure, an alarm system may be turned on and/or a feedback system may be initiated to control the pressure and flow rate such that the pressure and flow rates inside the fluid channels 212, 214, 216 and/or the drug reservoir 104 remain within safe operational values; this prevents drug expulsion or damage to the instrument 200 and/or the drug chamber 104.
The pumps 220, 222, 224 that are in fluid communication with the fluid channels 212, 214, 216 and handle the waste solution, wash solution and filling/refilling solutions may be standard mechanical pumps (e.g., gear, diaphragm, peristaltic, syringe, etc.) or pneumatic systems that create vacuum or adjust pressure in the individual channels. Pneumatic systems may include, but are not limited to, vacuum generators, air compressors, pneumatic motors, and pneumatic actuators, etc. The pumps 220, 222, 224 work cooperatively with the flow sensors 246, pressure sensors 248 and/or valves 238, 240, 242 to control the flow rate and/or pressure in the fluid channel 212, 214, 216 during the refilling process. In addition, the volume of fluid may be metered to prevent overfilling. If the drug reservoir 104 reaches full capacity such that the internal pressure begins to rise, pumps 220, 222, 224 may adjust the pressure such that fluid is injected less into the reservoir 104 and/or aspirated more from the reservoir 104. In one embodiment, the fluid injection pressure is monitored and maintained below a critical value when a liquid is infused into the drug reservoir 104 pneumatically. If the pressure exceeds the critical value, a pressure-release valve (not shown) may be used to reduce the pressure inside the channel. In another embodiment, if the liquid is infused using a mechanical pump, the pressure may be monitored and controlled by a pressure sensor 248 disposed at the point of highest hydraulic pressure; a feedback system 254 (e.g., control circuitry) may then be used to prevent the pressure at this point from exceeding the critical value. In general, the feedback system 254 is typically implemented on a printed circuit board (“PCB”) and may interface with the pumps 220, 222, 224 associated with the fluid channel 212, 214, 216, the flow sensors 246, the pressure sensors 248 and/or the valves 238, 240, 242. In response to the measured flow rates and/or pressures in the fluid channel, the feedback system 254 takes corrective action in order to ensure that the flow rate and/or pressure of the drug delivered through the channels remains within the critical range. For example, when receiving pressure data indicating that the pressure inside the fluid channel is too high, the feedback system 254 can automatically adjust operation of the pumps 220, 222, 224 and/or valves 238, 240, 242 to avoid excess pressure and/or maintain an optimal pressure or pressure range, thus preventing harm to the patient. The number of pumps used to drive the fluids in the channels may be different from (e.g., less than) the number of channels. For example, as depicted in
The feedback system 254, pumps 220, 222, 224 that are associated with the fluid channel, the flow sensors 246 and/or the pressure sensors 248, the valves 238, 240, 242, and/or the channels 212, 214, 216 may be implemented as a single unit or as multiple components. Referring to
In some embodiments, an electronic or mechanical locking system 266 is employed to prevent a user from injecting an unapproved fluid into the reservoir. The locking system may be based on, for example, electronic tags (e.g., RFID, barcodes, etc.) that are associated with the filling/refilling kit 264 described above. If improper tags are sensed, the instrument 200 may be programmed to prevent filling.
Although described above is a three-channel system, one of ordinary skill in the art will understand that systems may have different numbers of channels that ultimately terminate in the needle 210 and are within the scope of the current invention. For example, fewer independently controlled fluid channels may be utilized in the current invention. Referring to
As described above, the fluid channels may be interfaced to a flow control system ultimately terminating in a needle 210, which is used to pierce the access port and access the fluid reservoir 104. In one embodiment, the needle includes one lumen and all fluids from the channels travel in and out of the single lumen, as depicted in
The terms and expressions employed herein are used as terms and expressions of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof. In addition, having described certain embodiments of the invention, it will be apparent to those of ordinary skill in the art that other embodiments incorporating the concepts disclosed herein may be used without departing from the spirit and scope of the invention. Accordingly, the described embodiments are to be considered in all respects as only illustrative and not restrictive.
This application claims priority to and the benefit of, and incorporates herein by reference in its entirety, U.S. Provisional Patent Application No. 61/452,399, which was filed on Mar. 14, 2011.
| Number | Date | Country | |
|---|---|---|---|
| 61452399 | Mar 2011 | US |
