Abstract:
A therapeutic agent delivery pump includes a bottle having a pressurant chamber containing a pressurant and a therapeutic agent volume, the volume terminating in a visco-elastic septum. The bottle has a piercing element in alignment with the septum and in fluid communication with tubing. A flow restriction gauge impinges on the tubing to restrict the flow of a therapeutic agent from the balloon. An intrathecal drug delivery system includes a pump as described above, along with a pressure compatible catheter. A connector is provided between the pump and the catheter. An externally disposed therapeutic pump assembly for administering a therapeutic delivery agent in metered fashion to an internal location of a patient includes a three-dimensional body, with a lid secured to the body. A bag holding a volume of therapeutic delivery agent contained within the body in order to progressively compress.

Description:
RELATED APPLICATION  
       [0001]     This application claims priority of U.S. Provisional Patent Application Ser. No. 60/531,487 filed Dec. 19, 2003, which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention generally relates to an external therapeutic agent delivery pump intended for coupling to a catheter. In particular, the present invention teaches an external pump that urges a therapeutic agent from the pump, such as under a hydrostatic pressure, for delivery to an internally mounted and pump compliant catheter.  
       BACKGROUND OF THE INVENTION  
       [0003]     Catheter implantation has become a standard medical procedure in order to treat chronic cerebrospinal conditions such as pain. Subsequent to initial catheter implantation, a sophisticated therapeutic agent delivery pump is required in order to optimize therapeutic agent delivery dosimetry. However, with control of intrathecal dosimetry, devoting a complex pump for perpetual therapeutic administration becomes a considerable portion of the cost associated with intrathecal drug delivery. Thus, there exists a need for a simple, disposable external pump for intrathecal administration.  
       SUMMARY OF THE INVENTION  
       [0004]     A therapeutic agent delivery pump includes a bottle having a pressurant chamber containing a pressurant and a therapeutic agent volume, the volume terminating in a visco-elastic septum. The bottle has a piercing element in alignment with the septum and in fluid communication with tubing. A flow restriction gauge impinges on the tubing to restrict the flow of a therapeutic agent from the balloon.  
         [0005]     An intrathecal drug delivery system includes a pump as described above, along with a pressure compatible catheter. A connector is provided between the pump and the catheter.  
         [0006]     An externally disposed therapeutic pump assembly for administering a therapeutic delivery agent in metered fashion to an internal location of a patient includes a three-dimensional body, with a lid secured to the body. A bag holding a volume of therapeutic delivery agent contained within the body in order to progressively compress and administer the therapeutic agent in metered fashion to a catheter tube extending from the body. The catheter tube is in communication with the internal delivery location of the patient. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     Reference will be made to the attached drawings, when read in combination with the following detailed description, wherein like reference numerals refer to like parts throughout the several views, and in which:  
         [0008]      FIG. 1  is a schematic showing an inventive dispensing pump as part of an intrathecal therapeutic agent delivery system;  
         [0009]      FIG. 2  is a partial cutaway view of an inventive pump;  
         [0010]      FIG. 3  is an exploded view of a step-down hydrostatic pressure regulator component of an inventive pump;  
         [0011]      FIG. 4  is an expanded view of a mechanical caliper component of an inventive pump for metering therapeutic agent;  
         [0012]      FIG. 5  is a partial cutaway and exploded view of a therapeutic agent bottle according to the present invention;  
         [0013]      FIG. 6  is an alternate embodiment of a bottle according to the present invention depicting alternate port locations for pressurizing gas administration into a bottle;  
         [0014]      FIG. 7  is another embodiment of a bottle according to the present invention depicting alternate port locations for spring or gas-driven cylinder administration into a bottle;  
         [0015]      FIG. 8  is a perspective view of a rack and pinion pump assembly according to a further preferred embodiment of the present invention;  
         [0016]      FIG. 9  is an exploded view of the pump assembly of  FIG. 8  and further illustrating the components of the track, roller and progressively compressible therapeutic agent containing bag;  
         [0017]      FIG. 10  is an enlarged sectional view of the interengaging relationship between the cylinder track bed and cylinder bag roller;  
         [0018]      FIG. 11  is an exploded view of a flat spring variant of therapeutic agent delivery pump according to a further preferred embodiment of the present invention;  
         [0019]      FIG. 12  is an exploded view of the compressible bag and regulating delivery components associated with the embodiment of  FIG. 11 ; and  
         [0020]      FIG. 13  is an exploded view of a therapeutic delivery pump assembly according to a further preferred embodiment of the present invention and which includes an internally pressurized fill bottle in combination with an extending catheter tubing and associated regulator valve. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     The present invention has utility as a pump for intrathecal therapeutic agent delivery. By removing complex mechanical and electronic components from an inventive pump, intrathecal drug delivery is achieved with greater efficiency than previously performed. While the inventive pump is contemplated to be disposable, it is appreciated that pump reloading and recycling are readily performed.  
         [0022]     Referring now to  FIGS. 1-3 , an inventive external pump is shown generally at  10  as part of an intrathecal therapeutic agent delivery system. The pump  10  is coupled to an internal pump compliant catheter  12  by way of conventional pump compliant polymeric tubing  14 .  
         [0023]     An inline antimicrobial filter  16  (such as for example exhibiting a 0.22 micron rating) is preferably situated intermediate between the tubing  14  and catheter  12 . As is conventional with catheter implantation, the skin entrance point for the catheter is overlaid with an antimicrobial (anti-bacterial, anti-viral) shield  18 . Additionally, underlying the shield  18  is a catheter stabilization mesh  20  functioning to retain catheter position and orientation. It is appreciated that while the inventive pump  10  is detailed with respect to a typical implanted catheter, other variants of this catheter are operative herein.  
         [0024]     With particular reference to  FIG. 2 , an inventive pump  10  includes a housing  21  and a therapeutic agent balloon  22 . As used herein, a “therapeutic agent” is defined to include any drug or compound administered to promote a nutritional, therapeutic or other desired effect on a biological subject, the agent having a nutrient, stimulating action, inhibition, analgesic, destructive or regulatory effect on the subject where a subject is recognized to include a human, primate, domesticated animal and a plant.  
         [0025]     The therapeutic agent balloon  22  is encompassed within a pressurized bottle  24 . The surrounding pressurant illustratively includes a halocarbon, dinitrogen, a noble gas, carbon dioxide in combination thereof. The pressurant located within a pressurant chamber  26  exerts an external pressure on the drug balloon  22  that is compressible in response to the pressure exerted by the pressurant  26 .  
         [0026]     A pierceable cover  28  overlies the drug balloon  22  in a static condition prior to desired administration. Preferably, the cover  28  includes an antimicrobial coating operative to sterilize a piercing element  30 . The piercing element  30  penetrates the cover and enters the therapeutic agent balloon  22  in order to provide a route for therapeutic agent to escape from the bottle  24 . Preferably, the piercing element  30  is in fluid communication with a pump tubing  31 .  
         [0027]     Intermediate between piercing element  30  and catheter tubing  14 , a mechanical caliper  32  restricts the flow of therapeutic agent from said balloon  22 . A gauge  34  affords metering control of therapeutic agent from the balloon  22  into catheter tubing  16 . Preferably, the gauge  34  is accessible on the exterior of a pump housing  36 . More preferably, the gauge  34  is recessed in the housing  36  such that upon adjustment to a predetermined position, the gauge  34  is protected against inadvertent jostling.  
         [0028]     A therapeutic agent balloon  22  according to the present invention is formed of a drug compatible visco-elastic material molded to a thickness compatible with storage under pressure conditions associated within the bottle  24 . The bottle  24  is formed with a material capable to withstand the internal pressure therein of generally less than 100 atmospheres. Preferably, the pressurant is stored at a pressure between 3 and 20 atmospheres. The bottle  24  is illustratively formed of steel, aluminum, and high-impact plastic materials.  
         [0029]     With particular reference to  FIG. 3 , an inventive pump  10  is coupled to tubing  14  by way of a conventional connector  38 . Preferably, the connector  38  includes backward slanting external edges to inhibit inadvertent decoupling. While the coupler  38  is depicted as a linear connection between the pump tubing  31  and tubing  14 , it is appreciated that Y- and T-shaped connectors are illustratively operative herein in instances where one wishes to couple additional accessories in the tubing  14 .  
         [0030]     Representative accessories illustratively include a pressure transducer, a drug delivery port, and a second therapeutic agent delivery pump of conventional or inventive design. Preferably, intermediate between inventive pump tubing  31  and catheter  12 , a hydrostatic pressure interface plug  40  is provided that reduces the tubing diameter in fluid communication with the therapeutic agent to a smaller cross-sectional area relative to the tubing  14 .  
         [0031]     It is appreciated that a plug  40  is alternatively placed in the pump tubing  31 , or in the tubing connector  38 . Typically, the plug reduces the tubing internal cross-sectional area between  20  and  90  percent and thereby affords a pressure magnifying effect within the tubing  16  and catheter  12  so as to offer greater control over therapeutic agent administration.  
         [0032]     Referring now to  FIG. 4 , the caliper  32  is shown in an operational relationship relative to the gauge  34  and pump tubing  31 . The caliper  32  includes two opposing arms  41  and  42 . Preferably, the arms  41  and  42  each have an internal contoured surface generally complementary to the external surface of pump tubing  31 . Preferably, arm  41  is stationary while arm  42  is hingably moveable relative to arm  41  through enmeshment of worm gear teeth  44  with complementary threads  46  associated with a gauge shaft  48 , the gauge shaft  48  terminating in the gauge  34 . Thus, dial settings are provided on the gauge  34  as a percentage of total flow rate. For example, baclofen is provided at a 100% flow rate of 2500 micromiliters per day. The gauge gears  49  are preferably calibrated such that each increment of rotation corresponds to a predetermined percentage of total flow. Typical flow ranges are between 10% and 100% with increments of from 1% to 10% total maximum flow rate. Preferably, the increment is 5%.  
         [0033]     Referring now to  FIG. 5 , an inventive bottle  24  is shown in greater detail. The bottle  24  defines a pressurant chamber  26  in which the therapeutic balloon  22  is secured. Access to the therapeutic agent balloon  22  is by way of a visco-elastic septum  50 . The septum  50  optionally includes an inlet  52  in fluid communication with the pressurant chamber  26  so as to facilitate separate filling thereof. Preferably, the septum  50  has an antimicrobial coating  29  in order to inhibit microbial contamination of the therapeutic agent.  
         [0034]     The antimicrobial coating  29  illustratively includes a dried layer of topical antiseptics illustratively including chlorhexadine, Betadine, undecylenic acid, and/or benzalkonium chloride. The antimicrobial coating  29  is further protected by the pierceable cover  28 . The cover  28  formed of materials illustratively including metal foils, and plastics. Preferably, the cover  28  creates a sterile volume between the intersurface  55  thereof and the septum  50 . More preferably, the top surface  56  of the cover  28  also has an antimicrobial coating  29 .  
         [0035]     In an alternate embodiment of the inventive bottle depicted in  FIG. 6 , the bottle is shown generally at  60  where like numerals correspond to the descriptions with respect to  FIG. 5 . The bottle  60  in contrast to bottle  22  affords access to the pressurant chamber through an inlet  62  located in the wall  64  of the bottle  60 . Alternatively, an inlet  66  is provided in the base  68  of the bottle  60 . An inlet port such as  62  or  64  in concert with an aligned aperture in an external pump housing  21  affords one the ability to monitor and recharge the pressurant chamber  26  during the course of storage.  
         [0036]     In another embodiment of the inventive bottle depicted in  FIG. 7 , the bottle is shown generally at  70  where like numerals correspond to the descriptions with respect to  FIG. 5 . The bottle  70  in contrast to bottle  22  affords access to the pressurant chamber through an inlet  76  provided in the base  78  of the bottle  70 . A mechanical spring  80  and/or a gas driven cylinder  82  urges a therapeutic agent from the balloon  22 , or as depicted in  FIG. 7 a  therapeutic agent space  81  above the cylinder  82 . The cylinder  80  has an O-ring seal  84  with the interior wall of the bottle  70 . A cylinder stop-notch ring  86  is provided on the interior wall of the bottle  70  to preclude damage to a piercing element withdrawing therapeutic agent from a balloon within the bottle  70 .  
         [0037]     Referring now to  FIGS. 8 and 9 , both perspective and exploded views are shown of a rack and pinion pump assembly  88 , according to a further preferred embodiment of the present invention. The rack and pinion assembly provides an alternate arrangement for establishing a measured release of a therapeutic agent and includes a lid  90  secured over an interiorly hollowed (typically rectangular and box-shaped) base  92 . A downwardly extending latch  91  associated with the lid  90  seats within an aperture  93  associated with an end of the base  92  in order to lock in place a catheter tube (as subsequently referenced at  108 ). Additionally, screws  95  are provided to secure the lid  90  to the base such that the screws pass through aligning and mating apertures as illustrated.  
         [0038]     Seated within the base  92  is a geared roller  94 , this including circumferentially geared ends  96  and  98  which each seat upon a cylinder track bed, see as shown along one extending side at  100 , in both  FIGS. 9 and 10 . A compressible, sterilized bag  102  contains a desired fluidic agent and includes a first end  104  secured to a location of the geared roller  94  and such that, upon progressive rotation and translation of the roller  94 , the bag  102  is progressively wound about the outer circumferential area of the roller and its internal contents are progressively squeezed through an opposite end  106  located at a terminal point of the assembly and fluidly communicable with a catheter connecting tube  108 .  
         [0039]     A mixture injection point  110  is associated with the first end  104  of the compressible bag. In use, a control valve  112  is located at the end of the bag  102  proximate the catheter tube  108  and/or establishing a measured outflow of agent (such as rates including 1, 0.75 or 0.50 ml per diem) and which is set before the bag is filled and inserted within the base enclosure. Although not clearly shown, a needle  113  is associated with the second end  106  to facilitate outflow to the control valve  112  and catheter tube  108 .  
         [0040]     A tape backing is associated with the first end  104  of the bag which his slipped under and over the roller  94 . A tape backing  114  associated with the geared roller is removed and, upon winding of the roller, results in the bag being progressively wrapped thereabout. A counter-wound coil spring  116  is secured about an axle  118  and seats against a first end of the gear roller  94 . An opposing support axle  120  seats an opposite end of the gear roller  94  (again in proximity to the geared ends  96  and  98 ) and, upon the winding action of a crank (see at  122  in  FIG. 10 ), a sufficient degree of compression is maintained on the bag  102  in order to maintain sufficient pressure to empty the bag in an even and metered fashion. Additional features include an elongated slot  124  being formed along an extending side of the base  92  to provide for visual inspection of the volume of fluid remaining in the bag  102 .  
         [0041]      FIG. 11  is an exploded view is shown at  126  of a flat spring variant of therapeutic agent delivery pump according to a further preferred embodiment of the present invention. A lid  128  and base  130  are provided, similar to the arrangement illustrated in the embodiment of  FIGS. 8-10 .  
         [0042]     The base  130  includes an alternate configuration in the form of an angled and inwardly extending flat spring  132 , the purpose for which is to apply a consistent degree of pressure to a widthwise extending plate  134 , in turn secured to a fluid filled and compressible bag  136 . The plate  134  is mounted such that it translates along internal and smooth guides, see at  136  and  138 , to thereby maintain the necessary compressive force to empty the bag in metered fashion and with the optional assistance of a regulator component  140  arranged intermediate a welded-on plastic needle  142  (see  FIG. 12 ) and a catheter needle  144 .  
         [0043]      FIG. 13  is an exploded view, at  146 , of a therapeutic delivery pump assembly according to a further preferred embodiment of the present invention and which includes an internally (gas) pressurized fill bottle  148  in combination with an internal to external extending catheter tubing  150  and associated (screw down) regulator valve  152 . A lid  154  is secured atop an interiorly open base  156 , the lid including provision of locator setoffs  158 , the purpose for which being to secure the internal catheter tubing  150  in place during assembly.  
         [0044]     As previously described, the bottle  148  is internally pressurized such that, upon being pierced by a catheter bottle needle  160 , a fluid therapeutic delivery agent is expelled into the catheter tubing  150 . The regulator valve  152  includes a rotatable dial  162 , the purpose for which being to adjust the degree of pinching (compression) of a downwardly displaceable component  164 , in turn affecting the volume of fluid administered in metered fashion through the tubing  150 .  
         [0045]     A door  166  is pivotally mounted in the lid  154  and is opened to facilitate regulator adjustment. An alternative arrangement includes a pump body cover  168  formed in the base  156  and operable with a hinge and screw arrangement  170  to open and close a portion of the body to reveal the end of the internally pressurized bottle  148 , and such as to permit replacement thereof. Combination drainage holes  149  and a catheter tubing opening  151  are provided at locations along the body  156  as shown.  
         [0046]     It is appreciated that an inventive pump is readily designed to be amenable to the insertion of bottles containing different sizes of therapeutic agent balloons. Preferably, different size balloons are accommodated by modifying the bottle area without significantly changing the relative position of the septum relative to pump components.  
         [0047]     The process of charging a bottle with a therapeutic agent according to the present invention includes bottle sterilization. The balloon and septum are likewise sterilized in a seal formed between the septum and the pressurant chamber. Such a seal is readily formed, the methods conventional to the art illustratively including a threaded securement, sonic welding, and chemical adhesives. Upon testing the pressurant chamber seal and the separation thereof from therapeutic agent balloon contents, a pressurant is injected into the pressurant chamber either through a septum edge inlet as depicted in  FIG. 5 , or through an inlet  62  or  66  or  76 , as depicted in  FIGS. 6 and 7 .  
         [0048]     Thereafter, an antimicrobial coating is applied to the septum and a therapeutic agent injected through the septum into the therapeutic agent balloon. Cover application and the application of an antimicrobial coating complete the bottle assembly process. Upon piercing the cover and septum, the therapeutic agent is allowed to flow past the restrictions created by a mechanical caliper and an optional hydrostatic plug so as to administer the therapeutic agent at a preselected rate to administration apparatus in contact with a subject.  
         [0049]     It is appreciated that one skilled in the art upon reading the above description will recognize various modifications to the invention described herein that do not depart from the spirit of the invention. These modifications are intended to be encompassed by the appended claims.