Abstract:
A digestive tract barrier is provided that includes a material defining dimensions of a tube, said tube sized to deploy within the digestive tract of a subject. The material or stitches that make up the barrier disintegrate in a controlled manner. The disintegration precludes the need for a surgical procedure to retrieve the barrier and allows for increased nutritional absorption after behavior modification has occurred. Through the inclusion of opening or fenestrations in the barrier, bile flow and nutrition absorption are facilitated. Disintegration is facilitated by formation of the barrier from biodegradable material, stitching non-degradable swatches with disintegrating stitching, or the use of a MEMS cutter. A digestive barrier coated on either the interior or exterior of the tube facilitates management of conditions such as obesity, colitis, and Crohn&#39;s disease.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a non-provisional application that claims priority benefit of U.S. Provisional Application Ser. No. 60/736,820, filed Nov. 15, 2005; the contents of which are hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention in general relates to an intestinal nutrient absorption barrier and in particular to a disintegratable or segmentable barrier.  
       BACKGROUND OF THE INVENTION  
       [0003]     Obesity has reached pandemic proportion in the United States with 55% of adults and 25% of children classified as overweight. Increased meal portion sizes, a sedentary lifestyle, the proliferation of fad diets, and the increased carbohydrate calorie intake associated with low fat diets all contribute to this national health crisis. Some attributes of obesity include: 365,000 deaths per year related to morbid obesity, which is the second leading cause of death in U.S. behind tobacco (435,000 per year); high incidence of depression; higher incidence and poorer prognosis for cancers such as esophageal, prostate, colon, ovarian, cervical, breast, uterine cancer more common; as well as untold physical, economic and psychological impacts.  
         [0004]     As obesity progresses, the affected individuals develop medical comorbidities at alarming proportions. These include diabetes mellitus, heart disease, hypertension, dyslipidemia, degenerative joint disease, and numerous others. The five-year death rate among the untreated morbidly obese is over 6%, and this risk is reduced by 89% after successful weight loss surgery has been performed. Diabetes, which affects almost 80% of morbidly obese individuals, is improved in 85% after substantial weight loss and cured in 75%. Coronary artery disease is improved in 45%, hypertension in 55%, and the morbidity and mortality of joint replacement surgery markedly reduced in patients able to achieve meaningful weight loss, typically after weight loss or bariatric surgery.  
         [0005]     In extreme cases of morbid obesity that are untreatable through behavioral modification, diet and increased exercise, bariatric surgery is a dangerous final approach to reduce a patient&#39;s weight. Weight loss operations vary in aggressiveness, yet share the common feature of reducing or removing the stomach volume with an associated rearrangement of the small intestine to limit the amount of calories both ingested and absorbed. Some procedures solely restrict intake, and are known as restrictive procedures, while others combine restrictive and malabsorptive components to achieve even greater and more sustained weight loss. Unfortunately, the resultant weight loss is invariably accompanied by poor vitamin absorption, a predisposition to malnutrition, and potentially severe or life-threatening metabolic complications. Severe and life-threatening complications may result from surgery because of intestinal leaks from one or more of the intestinal anastomoses, pulmonary complications related to comorbid conditions like sleep apnea, deep venous thrombosis with pulmonary embolism, or postoperative myocardial infarction. Additionally, owing to the radical nature of bariatric surgery, reversal of the procedure upon reaching an optimal weight or suffering intolerable side effects is virtually impossible for many patients.  
         [0006]     Another approach to addressing obesity has been the deployment of a gastric and/or intestinal barrier that limits nutrient absorption by creating a physical barrier between the chymal mixture and intestinal epithelial cells. While such barriers have proven effective in reducing subject weight and are reversible through the retrieval of such a barrier, such barriers have met with limited acceptance. Representative barriers are disclosed in U.S. Pat. Nos. 4,134,505; 4,403,604; 4,416,267; and 5,306,300. Safety concerns have developed around these devices associated with barrier dislodgement or kinking, resulting in obstruction or barrier erosion through portions of the gastrointestinal tract resulting in infection, sepsis, and the need for emergency surgery. Additionally, the necessity for a second surgical procedure to safely collapse and retrieve a barrier in response to an intended or emergency retrieval also remains a concern.  
         [0007]     Thus, there exists a need for a digestive tract barrier that disintegrates in a controlled manner after deployment. There also exists a need for a variant barrier deployable to treat symptoms of colitis and Crohn&#39;s disease.  
       SUMMARY OF THE INVENTION  
       [0008]     A digestive tract barrier is provided that includes a material defining dimensions of a tube, said tube sized to deploy within the digestive tract of a subject. The material or stitches that make up the barrier disintegrate in a controlled manner from a distal end to proximal end relative to a securement that affixes the tube in a preselected position within the subject digestive tract. The disintegration precludes the need for a surgical procedure to retrieve the barrier and allows for increased nutritional absorption after behavior modification has occurred. Through the inclusion of opening or fenestrations in the barrier, bile flow and nutrition absorption are facilitated. Disintegration is facilitated by formation of the barrier from biodegradable material, stitching non-degradable swatches with disintegrating stitching, or the use of a MEMS cutter.  
         [0009]     A digestive barrier coated on either the interior or exterior of the tube facilitates management of conditions such as obesity, colitis, and Crohn&#39;s disease. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a perspective view of an inventive barrier depicted in the context of a human digestive tract; barrier segments are not shown to scale for illustrative purposes;  
         [0011]      FIG. 2  is a plan view of an inventive barrier having a helical construct having a nutrient transmissive portion;  
         [0012]      FIG. 3  is an exploded view of an alternate inventive barrier construct portion; and  
         [0013]      FIGS. 4A and 4B  are exploded views of an inventive barrier construct portions formed of biodegradable fiber (A) and sheeting (B). 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]     The present invention has utility as a digestive tract barrier that reduces overall digestive tract nutrient absorption from consumed foodstuffs. Indications for the deployment of an inventive barrier include obesity, colitis and Crohn&#39;s syndrome.  
         [0015]     An inventive barrier is characterized by a securement proximal to a first end, the first end deployed in an upper region of the digestive tract relative to the second end that descends for a predetermined length of intestine. Upon deployment, the barrier defines a bore through which chyme is transported, the barrier wall defining the bore is deployed in contact with the intestinal wall. The inventive digestive barrier inhibits nutrient transportation from the barrier bore to the intestinal wall where food absorption occurs. An inventive barrier is formed from a biodegradable component arrayed such that the lower portion of an inventive barrier, relative to the digestive tract, begins to degrade with the degradation successively moving upward. An inventive barrier by gradually degrading obviates the need for a surgical removal of the barrier and lessens the likelihood of bariatric surgery type side effects such as dumping syndrome. Dumping is an important part of behavioral modification after a gastric bypass; once a patient experiences dumping, behavior is modified to avoid a subsequent episode. With an inventive barrier, dumping is likely to occur at full barrier length, which creates the desired behavior modification even while the barrier thereafter disassembles. As a result, the behavior modification occurs while the likelihood of dumping actually reoccurring diminishes with a shortening barrier. In those subjects prone to develop gallbladder disease, an inventive barrier is optionally deployed that has an inclusion of a porous barrier segment in overlap with the bile duct or alternatively, the deployment of an inventive barrier in an intestinal region lower than the bile duct. While it is appreciated that diversion of the biliopancreatic stream is expected to lessen, the lowered risk of gallbladder disease associated with low motility justifies such a deployment.  
         [0016]     Referring now to  FIG. 1 , an inventive barrier is depicted generally at  10 . The barrier  10  has an upper end  12  and a lower end  14 . A securement  16  is located proximal to the upper end  12  and serves to anchor the barrier  10  while deployed. The nature of the securement  16  is dictated by the criteria of being: collapsible to safely be excreted, and compatible with residence in the digestive tract for a period of time ranging from two weeks to several years. Exemplary securements operative herein illustratively include a tissue adhesive, sutures, and a resilient member biased against surrounding digestive tract tissue. In the embodiment depicted in  FIG. 1 , the securement  16  engages the duodenum beneath the bile duct so as to promote normal gallbladder motility. The securement  16  is a flexible cartilaginous incomplete ring segment. It is appreciated that a plurality of like securements  16  or a combination of different types of securements are suitable to anchor the upper end  12  of an inventive barrier  10 . By way of example, a cartilaginous ring segment may be used in combination with another cartilaginous ring segment, a full cartilage ring, a spring, or a polymerizable tissue adhesive. The tissue adhesive, if present, is in the form of a burstable packet or applied through a multiple bore catheter. The barrier wall  18  extends from the securement to the lower end  14 . The barrier wall  18  is composed of multiple swatches  20  of implant-compatible non-degradable fabric or sheet polymer. Suitable materials for a swatch  20  illustratively include nylon, fluoropolymers, and polyimides. The swatches  20  are secured together by way of a stitching  22 .  
         [0017]     The stitching  22  is in the form of a biodegradable fiber or a scissionable nonbiodegradable fiber. Regardless of the characteristics of the fiber and separation methodology, the inventive barrier is partially removable.  
         [0018]     Scission of a nonbiodegradable fiber stitching in the inventive barrier entails deployment of an endoscopic cutting implement to selectively cut portions of the barrier  10  free from the lower end  14 . Alternatively, a nonbiodegradable fiber is deployed as stitching that is degraded by ultraviolet light or transient heating. Upon a portion of an inventive barrier being exposed to ultraviolet emissions or transient heating inducing laser light produced by an endoscopic light source, such portion is released from the lower end  14 . Ultraviolet light degradable stitching is formed from a polymer, illustratively including cassava starch, poly ter-alkylmethacrylate cellulose, and lignin. Stitching susceptible to transient heat degradation is formed from a polymer illustrative including polymethacrylates such as alkyl and hydroxyalkyl and polytetrafluoroethylene. In another embodiment nonbiodegradable fiber stitching is selectively scissionable through the deployment of a passive radiofrequency identification (RFED) tag in operative control of a stitch cutter such as an electro-micromechanical microcutter powered by an electrostatically driven harmonic micromotor as detailed in K. S. Shea et al., J. Micromech. Microeng. 5, 297-304 (1994), the contents of which are incorporated by reference as to the construction of a microcutter; a battery-powered UV LED; or a thermoresistive element. Communicating an activating radiofrequency to the RFID tag engages the stitch cutter positioned proximal to a stitch to cut the stitch thereby releasing a portion of the barrier device. It is appreciated that the deployment of multiple stitch cutters along the length of an inventive barrier, and activated by different radiofrequency signals allows not only a noninvasive method of determining the position and length of the barrier but also a highly controlled truncation method.  
         [0019]     Biodegradable polymers operative herein for the formation of fibers, stitches or sheets illustratively include polyglycolic acid, polylactide, polyglyconate, and copolymers thereof. The diameter of a biodegradable fiber from which the stitching  22  is formed increases in cross-sectional area from the lower end  14  to the upper end  12 . As the degradation rate and therefore scission time for a stitch  22  increases with an increased diameter for the biodegradable thread from which the stitch  22  is formed, this pattern of stitching induces a generally sequential degradation beginning at the lower end  14 . Optionally, the stitching  22  is in the form of a rip stitch or “daisy chain” such that a degradation portion illustratively including a circumference defining series of swatches are released from the end  14  upon a single failure in a stitch  22  within a degradation portion  24 . Alternatively, a biodegradable fiber is non-uniformly coated with a semi-permeable diffusion coating that controls the rate of underlying biodegradable fiber degradation. A semi-permeable diffusion coating is formed from materials illustratively including gelatin, cellulose, and polylactic acid.  
         [0020]     Optionally, the inner surface, outer surface or both inner and outer surfaces are coated with a biodegradable coating  30 . It is appreciated that the coating thickness need not be uniform and by way of example may include a continuous thickness gradient of coating, a discontinuous region of a coating, or a coating application only over a specific barrier component such as a swatch  20  or a stitch  22 . A coating  30 , if present, optionally includes an adjuvant such as a lubricant; a vitamin; an antimicrobial; an anti-inflammatory; a hormone; an enzyme; a radio-opacifying agent; an appetite suppressant such as hoodia; an appetite stimulant such as Megase; and combinations thereof. Incorporation of an enzyme such as mung bean extracted enzymes is contemplated to convert ingested carbohydrate into non-metabolizable material by the subject. Appetite stimulants are contemplated as particularly beneficial with a short length contact therapeutic device for subjects such as those with malignancy. It is appreciated that incorporating a radio-opacifying agent into a barrier coating facilitates fluoroscopic and x-ray monitoring of barrier placement and condition. Radio-opacifying agents illustratively include barium sulfate and gold nanoparticulate. It is appreciated that coating adjuvants intended to be absorbed through intestinal epithelial cells are present within a coating matrix found on the barrier exterior surface  28 . Vitamin B12 is representative of a vitamin typically deficient in a dieting subject and is well suited to intercalation into a barrier coating  30  on the exterior surface  28 .  
         [0021]     In employment of an inventive barrier  10  in a subject suffering colitis or Crohn&#39;s disease, the portion of the inventive barrier contacting inflamed intestinal tissue is formed of a gold mesh or has an exterior coating impregnated with therapeutics such as steroidal or non-steroidal anti-inflammatories, gold, or combinations thereof. The inventive barrier  10  in such a case affords the advantage of continual, contact delivery of therapeutics through diffusion from the barrier coating and depending on the specifics of the therapeutic medicament, at doses higher than deliverable through conventional administration routes. In a particular embodiment, the barrier coating  30  releases metronidazole to inhibit chlamydia proliferation in a subject so infected. A coating  30  on an interior surface in addition to protecting the wall  18  from abrasion, optionally includes adjuvants such as antacids, antioxidants, lubricants and the like.  
         [0022]     Referring now to  FIG. 2 , an inventive barrier is depicted generally at  40  where like numerals correspond to those detailed above with respect to  FIG. 1 . The barrier  40  is particularly well suited for the treatment of Crohn&#39;s disease and is characterized by an impermeable barrier wall portion  42  and an upstream nutrient transmissive portion  44 . The nutrient transmissive portion  44  is constructed with fenestrated swatches or only stitch thread extending between the securement  16  and the transmissive portion  44 . An inventive barrier  40  preferably includes a coating  30  on the exterior surface  28  of the nutrient impermeable portion  42  of the barrier  40 . The coating  30  is preferably impregnated with a diffusible contact therapeutic for the treatment of intestinal inflammation and associated clinical manifestations. Without intending to be bound by a particular theory, it is believed that the barrier  40  provides therapeutic benefits through limiting exposure of inflamed intestinal tissue to digestive tract contents and delivering through contact diffusion suitable therapeutics for the intestinal tissue inflammation.  
         [0023]     Referring now to  FIG. 3 , an inventive barrier end with a helical construct pattern is provided generally at  60 , where like numerals correspond to those detailed above with respect to  FIG. 1 . Preferably, the swatches  20  are formed as parallelograms thereby defining helical stitch lines between the intersection of contiguous swatches. Preferably, the stitches  22  securing a particular swatch are self-limiting such that dissolution of a particular stitch is self-limiting and does not cause the entire helix to unravel. Rather, each swatch  20  is sequentially released from the end  14 .  
         [0024]     An inventive barrier construction woven of biodegradable fiber is shown generally in  FIG. 4A  at  80 , where like numerals correspond to those detailed above with respect to  FIG. 1 ; and an inventive barrier construction sheet is shown generally in  FIG. 4B  at  90 , where like numerals correspond to those detailed above with respect to  FIG. 1 . A barrier  80  is formed from biodegradable polymer in the form of fibers  82 . The barrier  90  is preferably rolled in the form of a tube and has stitches  92  or is secured with a tissue adhesive  94  as collectively shown in  FIG. 4B . The stitches  92  or tissue adhesive  94  are chosen to disintegrate slower than the biodegradable polymer, if at all. Alternatively, a biodegradable material is molded through an extrusion die or injection molded to form a seamless barrier (not shown). The attribute of a gradual disintegration initiating at the lower end  14  and moving up the barrier  80  or  90  is provided by increasing the thickness of the woven fiber or sheet material from the lower end and increasing towards the upper end. Alternatively, a uniform thickness sheeting material or diameter fiber is coated with a semi-permeable encapsulant layer  96  applied in a gradient with the least amount of the semi-permeable layer being present at the lower end. Optionally, a barrier semi-permeable layer coating has a set of score marks  98  in the coating  96  to facilitate coating disintegration into readily excretable particulate. A suitable semi-permeable coating layer is formed from a material illustratively including gelatin, cellulose, and polylactic acid. It is appreciated that adjuvants as detailed above are readily incorporated into a semi-permeable coating.  
         [0025]     An inventive barrier is deployed through a variety of techniques conventional to the art. Such techniques include endoscopic deployment, laparoscopic deployment, toposcopically so as to push the inverted barrier into position, with resort to a guide wire, or in a dehydrated and compressed state. It is appreciated that the compression can be lateral or transverse to the barrier central axis.  
         [0026]     Patent documents and publications mentioned in the specification are indicative of the levels of those skilled in the art to which the invention pertains. These documents and publications are incorporated herein by reference to the same extent as if each individual document or publication was specifically and individually incorporated herein by reference.  
         [0027]     The foregoing description is illustrative of particular embodiments of the invention, but is not meant to be a limitation upon the practice thereof. The following claims, including all equivalents thereof, are intended to define the scope of the invention.