Abstract:
The present disclosure is directed to a device for locating a fistula. The device can include a first tine and a second tine each having a distal end and a proximal end with the first tine spaced a distance from the second tine sufficient for allowing a section of a fistula to fit therebetween. A compression member can be placed adjacent to the first tine and the second tine such that the compression member externally compresses and temporarily occludes a fistula thereby increasing blood pressure in a section of a fistula located between the first tine and the second tine.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    The present application is based on and claims priority to U.S. Provisional Application Ser. No. 60/710,209 having a filing date of Aug. 22, 2005. 
     
    
     BACKGROUND 
       [0002]    End-stage renal disease (ESRD) is characterized by a complete or near complete failure of the kidneys to function to excrete wastes, concentrate urine, and regulate electrolytes. In such cases, kidney function is so low that complications are multiple and severe, and death will occur from accumulation of fluids and waste products in the body. 
         [0003]    A common life-sustaining treatment for patients with ESRD is hemodialysis. Hemodialysis is a process whereby large amounts of blood are rapidly removed from the body and filtered through a machine that removes wastes and extra fluid. The cleaned blood is then returned back into the body. 
         [0004]    An important step before starting regular hemodialysis is preparing a vascular access, which is a site on the body where blood will be removed and returned during dialysis. In this regard, creation of an arteriovenous fistula (AV fistula) is a commonly performed operation in which an artery is connected directly to a vein. The high blood pressure of the artery causes more blood to flow into the vein and, as a result, the vein dilates growing larger and stronger. 
         [0005]    However, to connect the patient to a dialysis machine, a nurse or some other medical technician must insert a large gauge needle through the skin into the AV fistula. The technique of cannulating an AV fistula for dialysis requires considerable skill. The AV fistula often lies several centimeters below the surface of the skin and cannot be located by visual inspection. A medical technician is forced to locate the AV fistula by palpation. Since resistance to blood flow in the vein is low, a pulse is usually not present in the AV fistula. The tactile clue utilized to locate the AV fistula is a vibration caused by turbulent blood flow in the vein. The medical technician tries to identify the location of maximum vibration on the surface of the skin with his/her fingertip to identify the location of the underlying AV fistula in order to cannulate it. If the medical technician is unable to properly identify the correct location of the AV fistula, the dialysis needle may inadvertently puncture the side rather than the center of the AV fistula and result in damage and significant bleeding or thrombosis of the AV fistula. Thus, a need exists for a device and method that can simplify the technique of AV fistula cannulation. 
       SUMMARY 
       [0006]    Objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
         [0007]    The present disclosure is directed to a device for locating a fistula. The device can include a first tine and a second tine each having a distal end and a proximal end with the first tine spaced a distance from the second tine sufficient for allowing a section of a fistula to fit therebetween. A compression member can be placed adjacent to the first tine and the second tine such that the compression member externally compresses and temporarily occludes a fistula thereby increasing blood pressure in a section of a fistula located between the first tine and the second tine. 
         [0008]    In certain embodiments of the device, the first tine and the second tine may be connected together at each proximal end. The first tine and the second tine may be connected together at each proximal end and each distal end such that they generally form an o-shape. The first tine and the second tine may be pivotally connected together at their proximal ends such that the distance between the first tine and the second tine is adjustable. The first tine and the second tine may be formed from a malleable material such that the distance between the first tine and the second tine is adjustable. The compression member may be integrally connected with the first tine and the second tine. The compression member may be attached to the first tine and the second tine. The compression member may be formed from the same material as the first tine and the second tine. The compression member, first tine, and second tine may be formed from plastic. The compression member, first tine, and second tine may be formed from a material having antibacterial properties. 
         [0009]    In another embodiment of the present disclosure, a device for locating a fistula is disclosed. The device can include a first tine and a second tine each having a distal end and a proximal end and the first tine and a second tine being integrally connected together at each proximal end, the first tine spaced a distance from the second tine sufficient for allowing a section of a fistula to fit therebetween. A compression member can be integrally connected with the first tine and second tine such that the compression member externally compresses and temporarily occludes a fistula thereby increasing blood pressure in a section of a fistula located between the first tine and the second tine. 
         [0010]    In still another embodiment of the present disclosure, a method for locating a fistula is disclosed. The method includes providing a device having a first tine, a second tine, and a compression member, positioning the first tine and the second tine a distance sufficient for allowing a section of a fistula to fit therebetween, positioning the compression member adjacent to the first tine and the second tine such that the compression member externally compresses and temporarily occludes a fistula thereby increasing blood pressure in a section of a fistula located between the first tine and said the tine. 
         [0011]    Other features and aspects of the present disclosure are discussed in greater detail below. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0012]    A full and enabling disclosure, including the best mode thereof to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures in which: 
           [0013]      FIGS. 1-4  illustrate successive steps of positioning and operating a device to locate and cannulate a fistula in accordance with one embodiment of the present disclosure; 
           [0014]      FIGS. 5-9  depict a device to locate a fistula in accordance with one embodiment of the present disclosure; 
           [0015]      FIG. 7  is a cross-sectional view taken along line  7 - 7  of  FIG. 5 ; and 
           [0016]      FIG. 9  is a cross-sectional view taken along line  9 - 9  of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only, and is not intended as limiting the broader aspects of the present invention, which broader aspects are embodied in the exemplary construction. 
         [0018]    In general, the present disclosure is directed to devices and methods to facilitate cannulation of an arteriovenous (AV) fistula. In particular, the devices and methods described herein greatly simplify the technique of arteriovenous fistula cannulation by improving a technician&#39;s ability to locate a fistula. 
         [0019]    Very generally, a fistula is a connection between two parts of the body that are usually separate. An AV fistula is useful because it allows for easy access to the blood system of a patient. Creation of an AV fistula is a commonly performed operation in which an artery is connected directly to a vein. The high blood pressure of the artery causes more blood to flow into the vein and, as a result, the vein dilates growing larger and stronger. An AV fistula is considered the best long-term vascular access for hemodialysis because it provides adequate blood flow for dialysis, lasts a long time, and has a complication rate lower than other types of access. When cannulated correctly, a properly formed AV fistula is less likely than other kinds of vascular accesses to form clots or become infected. Also, AV fistulas tend to last many years, longer than any other kind of vascular access. 
         [0020]    However, once an AV fistula is formed, the tactile clue that a technician uses to locate it (a vibration caused by turbulent blood flow in the vein) is difficult to locate at best. A technician tries to identify the location of maximum vibration on the surface of the skin with his/her fingertip to identify the location of the underlying fistula in order to cannulate it. The present devices and methods enhance a technician&#39;s ability to locate an AV fistula by transforming the tactile clue the technician uses to locate the AV fistula from a vibration to a pulse. 
         [0021]    Referring now to  FIGS. 5-7 , a fistula-locating device  10  in accordance with one embodiment of the present disclosure is shown. The fistula-locating device  10  comprises two tines  12 ,  14  and a compression member  16 . 
         [0022]    The two tines  12 ,  14  are generally equal in length and width. The two tines  12 ,  14  can be formed from any suitable material known in the art such as a type of plastic material, an elastomeric material, or a metal. In some embodiments, the two tines  12 ,  14  can be formed from a suitable material that has antibacterial properties. 
         [0023]    In some embodiments, the two tines  12 ,  14  each have a proximal end  13  and a distal end  15 . The two tines  12 ,  14  are positioned such that they are joined at their proximal end  13 . The distal end  15  of each tine  12 ,  14  can include a projecting member defining a top surface  23  and a contact surface  24 . The contact surface  24  projects downward at a slant and can form an edge that contacts the patient. 
         [0024]    In some embodiments, the two tines  12 ,  14  are positioned adjacent to one another and connected such that together they generally form a u-shape or v-shape. In other embodiments, the two tines  12 ,  14  can be connected at their distal end  15  as well such that they generally form an o-shape. 
         [0025]    The two tines  12 ,  14  should be positioned a sufficient distance apart so as to allow a section of AV fistula to fit therebetween. In some embodiments, at least a portion of the distal ends  15  of the two tines  12 ,  14  are spaced between about 1 to 4 cm apart. In accordance with the present disclosure, however, at least a portion of the two tines  12 ,  14  should be spaced a sufficient distance apart to allow for a section of AV fistula  22  to fit therebetween. 
         [0026]    Referring to  FIGS. 5 and 6 , in some embodiments the two tines  12 ,  14  can be integrally connected together. With reference to  FIGS. 8 and 9 , in some embodiments the two tines  12 ,  14  can be connected together by a pin  18  such that the distance between the two tines  12 ,  14  can be adjusted. In such embodiments, the pin  18  can be connected to a spring  20  so that the two tines  12 ,  14  return to their initial position after adjustment. Such embodiments allow a technician to decrease the distance between the tines  12 ,  14  to accommodate a smaller AV fistula  22 . In still other embodiments, the two tines  12 ,  14  are connected together by attachment methods as would be known to one of ordinary skill in the art. Examples of such attachment methods include adhesives, mechanical fastening, and the like. 
         [0027]    In other embodiments, the distance between the two tines  12 ,  14  can be adjustable by other means. For example, in some embodiments, the two tines  12 ,  14  can be formed from a malleable material in which the distance between the two tines  12 ,  14  can be adjusted a sufficient distance to allow a section of AV fistula  22  to fit therebetween. 
         [0028]    The fistula-locating device  10  also comprises a compression member  16 . In some embodiments, the compression member  16  has a generally rectangular shape. The compression member  16  should be of sufficient length and width so as to externally compress and temporarily occlude an AV fistula  22 . The compression member  16  can be formed from the same material as the two tines  12 ,  14 . However, the compression member  16  can be formed from any suitable material known in the art such as a plastic or metal. In some embodiments, the compression member  16  can be formed from a suitable material that has antibacterial properties. 
         [0029]    In some other embodiments, the compression member  16  is integrally connected to the tines  12 ,  14 . In some embodiments, the compression member  16  extends below the tines  12 ,  14  at an angle from a plane defined by the top surfaces  23  of the tines  12 ,  14 . In still other embodiments, the compression member  16  is slanted at an angle ranging from between about 60 to 90 degrees from the plane defined by the top surfaces  23  of the two tines  12 ,  14 . 
         [0030]    In some embodiments, the compression member  16  is connected to the tines  12 ,  14  by attachment methods as would be known to one of ordinary skill in the art. Examples of such attachment methods include adhesives, mechanical fastening, and the like. In still other embodiments, the compression member  16  is not connected to the tines  12 ,  14  at all. 
         [0031]    In some embodiments, the compression member can include an indention  11 . Indention  11  allows a technician to more easily grip the compression member  16  to externally compress and temporarily occlude the AV fistula  22 . 
         [0032]    Referring now to  FIGS. 1-4 , the use of the device  10  for locating an AV fistula  22  will be described in detail. Referring now in particular to  FIGS. 1 and 2 , an embodiment of the device  10  is positioned externally above the general location of the AV fistula  22 . The device  10  is positioned such that the compression member  16  is placed generally above the AV fistula  22  distal to the arterial anastomosis (surgical union of the artery and vein). The contact surfaces  24  of the device  10  project downward at a slant and form an edge that contacts the patient. 
         [0033]    As illustrated in  FIG. 3 , once the device  10  is properly positioned, a technician compresses the compression member  16  so as to externally compress and temporarily occlude the AV fistula  22 . Blood flow restriction through the AV fistula  22  caused by the compression member will result in distention of the fistula between the two tines  12 ,  14  and will convert a vibration in the AV fistula  22  into a pulse which can be easily detected between the two tines  12 ,  14 . As a result, referring to  FIG. 4 , a technician is able to simply insert a needle between the two tines  12 ,  14  of the device  10 . 
         [0034]    The tines  12 ,  14  mark the lateral borders of the AV fistula  22 , which provides a visual clue to a technician with regards to the location of the AV fistula  22 . In addition, the increased blood pressure in the AV fistula  22  caused by the compression member  16  causes the AV fistula  22  to dilate, which further facilitates cannulation. In this manner, a technician can easily identify the correct location of the AV fistula and the dialysis needle can be inserted without damage and significant bleeding or thrombosis to the AV fistula  22 . 
         [0035]    These and other modifications and variations to the present disclosure may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. In addition, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only and is not intended to limit the invention so further described in such appended claims.