Patent Publication Number: US-2012029525-A1

Title: Medical device and method for vascular access

Description:
BACKGROUND 
     Hemodialysis is used to provide artificial replacement of lost kidney function caused by certain kidney diseases. The process consists in recirculating the patient&#39;s blood through a dialysis filter in order to remove toxins and excess fluid. In order to do this procedure, the patient needs to be connected to the hemodialysis machine via an access. This is done by either an access in the patient&#39;s limb (fistula or graft), or a temporary catheter inserted into the patient&#39;s central vein. The safest, most efficient and most common access is a permanent access in a limb. For this purpose, a surgeon will join an artery with a vein, either directly (fistula) or through a synthetic tube of PTFE (graft). The dialysis personnel then will insert two large bore needles connected to the tubing that takes the blood to the machine for the dialysis process. This procedure is performed for 3 to 4 hours, three times a week. It is a matter of time that, due to repeated needle punctures and other factors, the access will malfunction, or stop functioning altogether, and clot. The most common cause for this malfunction is a critical narrowing of the access to the point of slowing down or stopping the circulation of blood. At this point, the patient cannot be dialysed and access viability needs to be restored. The state of the art procedure to restore blood flow to a malfunctioning or clotted access is by inserting two sheaths at opposite ends of the access, and using embolectomy catheters, and angioplasty balloons, remove the clots, and dilate the narrowed blood vessels. This is done under fluoroscopy which exposes the operator and the assistants to radiation. The initial insertion of the first sheath is usually easy, since that segment of the access is better exposed. The second insertion can sometimes be very difficult since the area is sometimes less exposed, specifically in the upper arm, or thighs of patients. When this happens, the time of the procedure is prolonged significantly, and so is the exposure to radiation. The present medical device has the purpose of circumventing this problem by using the first insertion to exteriorize a needle at the desired site of the second insertion and using this guide to enter the access for the second time thus significantly shortening procedure time and radiation exposure in difficult cases. 
     SUMMARY 
     The problems noted above are solved in large part by a medical device and method. In some embodiments, a medical device comprises a rod which includes an elongate rod body and a rod handle. The rod body is composed of a biocompatible semi-rigid material and is curved from between 75 to 105 degrees relative to the longitudinal axis of the rod body. The distal end of the rod body is beveled to a point so that it is capable of puncturing through human skin. The medical device also comprises a sheath which includes a hollow sheath body and a sheath handle. The sheath body is substantially straight. The rod body is capable of being inserted into the sheath body and is able to slide along the sheath body&#39;s longitudinal axis. In some embodiments the rod body may be composed of a Nitinol alloy and may be hollow. The sheath handle and rod handle may be composed of non-slip materials. Additionally, in some embodiments, the distal end of the rod body is superelastic. 
     Another illustrative embodiment includes a medical device comprising a rod which includes an elongate rod body and rod handle. The rod also includes a first position and a second position. The medical device also comprises a sheath which includes a sheath body and a sheath handle in which the sheath body is substantially straight. When the rod is in the first position, the distal end of the rod body is fully disposed within the sheath body. When the rod is in the second position, the distal end of the rod body is extended from the sheath body and oriented about 90 degrees relative to the longitudinal axis of the sheath body. In some embodiments, when the rod is in the first position, the rod handle is horizontally separated from the sheath handle. When the rod is in the second position, the rod handle is in contact with the sheath handle. 
     Yet another illustrative embodiment includes a method comprising making a first insertion on a patient. The method also comprises inserting a rod body entirely disposed within a sheath body into the patient through the first insertion. The method continues with sliding the rod body longitudinally along the sheath body until a distal end of the rod emerges from the sheath body at about a 90 degree angle relative to the longitudinal axis of the sheath body. The method also comprises puncturing the skin of the patient with the distal end of the rod body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a detailed description of various disclosed embodiments, reference will now be made to the accompanying drawings in which: 
         FIGS. 1   a ,  1   b , and  1   c  show detailed views of a rod which may be used in assisting in making an insertion on a patient from inside the patent, in accordance with various embodiments of the invention; 
         FIGS. 2   a ,  2   b , and  2   c  show detailed views of a sheath which may be used in assisting in making an insertion on a patient from inside the patent, in accordance with various embodiments of the invention; 
         FIG. 3  shows a detailed view of a rod and sheath in combination with the rod fully inside the sheath which may be used in assisting in making an insertion on a patient from inside the patent, in accordance with various embodiments of the invention; 
         FIG. 4  shows a detailed view of a rod and sheath in combination with the rod exiting the sheath which may be used in assisting in making an insertion on a patient from inside the patent, in accordance with various embodiments of the invention; 
         FIGS. 5   a  and  5   b  show a patient in which a rod and sheath combination is being used, in accordance with various embodiments of the invention; 
         FIG. 6  shows an illustrative flow diagram of a method implemented in accordance with embodiments of the invention. 
     
    
    
     NOTATION AND NOMENCLATURE 
     Certain terms are used throughout the following description and claims to refer to particular device components. As one skilled in the art will appreciate, companies may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices and connections. Further, the terms “axial” and “axially” generally mean along or parallel to a central or longitudinal axis (e.g., the sheath body), while the terms “radial” and “radially” generally mean perpendicular to the central or longitudinal axis. For instance, an axial distance refers to a distance measured along or parallel to the central or longitudinal axis, and a radial distance refers to a distance measured perpendicularly from the central or longitudinal axis. Further, the terms “coaxial” and “coaxially” generally refer to the relative orientation of two structures or components that have coincident central or longitudinal axes. 
     DETAILED DESCRIPTION 
     The following discussion is directed to various embodiments of the invention. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. In addition, one skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment. 
     Some embodiments include a device which is capable of being inserted into a patient&#39;s blood vessels, and, at a desired location, making a second insertion on the patient from within the patient himself/herself. This enables a physician to gain vascular access at a location in the body which may be difficult to obtain otherwise due to, for example, the size of the patient&#39;s body or appendage where the vascular access is required. 
       FIGS. 1   a ,  1   b , and  1   c  show detailed views of a rod  100  which may be used in assisting in making an insertion on a patient from inside the patent, in accordance with various embodiments of the invention.  FIG. 1   a  shows a detailed view of rod  100  as viewed as from the side, in accordance with various embodiments of the invention. Rod  100  is comprised of rod handle  102 , rod housing  104 , rod body  106 , and distal end  108  which is a section of rod body  106 . In some embodiments, rod handle  102  may be 5 centimeters in length and 2 centimeters in width; however, other lengths and widths may also be used in other embodiments, so long as a physician may hold and guide rod  100 . Rod handle  102  preferably is manufactured of a non-slip material. That is, rod handle  102  is preferably manufactured with a material that will not slip in a physician&#39;s hand when rod handle  102  has body fluid (e.g. blood) on its surface. Some such materials include materials with a relatively high coefficient of friction, e.g. rubber, or a textured metal or plastic surface, e.g. ridged, knurled, or notched. However, rod handle  102  may have a smooth surface, so long as a physician may hold and guide rod  100 . 
     Rod housing  104  is radially coupled to rod handle  102  and axially coupled to rod body  106 . Rod housing  104  is tubular, such that rod body  106  may extend through it. Rod housing  104  may be 3 centimeters in length and 5 millimeters in width, although other lengths and widths may be used. Rod housing  104  preferable is square in shape, but may be of other shapes (e.g. circular, hexagonal, octagonal). Rod housing  104  may be made of any rigid material, such as stainless steel. 
     Rod body  106  is substantially straight until it reaches distal end  108  where it curves. In at least some embodiments, “substantially straight” means straight plus or minus three degrees. Rod body  106  preferably is smooth, so that it may slide easily along a sheath. Rod body  106  may be approximately 1 millimeter in diameter, and approximately 20 centimeters in length, although it may be more or less in both diameter and length. Rod body  106  may be hollow throughout its length, and thus tubular. Rod body  106  may be manufactured with any biocompatible material; so long as the material remains semi-rigid (e.g. a Nitinol alloy). Semi-rigid means that the material must be capable of bending under pressure, but remains rigid without pressure. Rod body  106  is axially coupled to rod housing  104  and radially coupled to rod handle  102  so that rod body  106  extends beyond rod housing  104  and rod handle  102 . 
     Distal end  108  is a section of rod body  106  which is curved in the direction of rod handle  102 . In some embodiments the length of distal end  108  may be 1.5 centimeters although the length may vary. Preferably, distal end  108  is radially curved approximately 90 degrees from the longitudinal axis of the rest of rod body  106 . Thus, distal end  108  is preferably curved about 90 degrees relative to the longitudinal axis of the rest of rod body  106 . However, distal end  108  may be radially curved as little as 75 degrees and as much as 105 degrees from the longitudinal axis of the rest of rod body  106 . Like the other sections of rod body  106 , distal end  108  is bendable, meaning that the angle of the curve may be increased or decreased. For example, distal end  108  may be bent such that the angle of the curve decreases to zero degrees relative to the longitudinal axis of the rest of rod body  106 . However, distal end  108  will remain curved unless force is applied and will return to its original curved shape when the applied force is removed. This is sometimes referred to as superelasticity. Distal end  108  is beveled to a point, such that it is capable of puncturing through human skin and blood vessels. 
       FIGS. 1   b  and  1   c  show different cross sectional views of rod  100 , in accordance with various embodiments of the invention.  FIG. 1   b  is a cross sectional view from the rear of rod  100  longitudinal to rod body  106 . As can be seen, rod body  106  extends through rod handle  102 . Rod body  106  is a hollow tube such that a thin wire may extend through its shaft.  FIG. 1   c  is a cross sectional view of rod  100  from its front longitudinal to rod body  106 . Rod housing  104  is hollow so that rod body  106  extends through both sides of it. Distal end  108  comes to a point so that it may puncture through skin and blood vessels. 
       FIGS. 2   a ,  2   b , and  2   c  show detailed views of a sheath  200  which may be used with rod  100  in assisting in making an insertion on a patient from inside the patent, in accordance with various embodiments of the invention.  FIG. 2   a  shows a detailed view of sheath  200  as viewed from the side, in accordance with various embodiments of the invention. Sheath handle  202  may be 5 centimeters in length and 2 centimeters in width; however, other lengths and widths may also be used, so long as a physician may hold and guide sheath  200 . Sheath handle  202  preferably is manufactured of a non-slip material. That is, sheath handle  202  is preferably manufactured with a material that will not slip in a physician&#39;s hand when sheath handle  202  has body fluid (e.g. blood) on its surface. Some such materials include materials with a relatively high coefficient of friction, e.g. rubber, or a textured metal or plastic surface, e.g. ridged, knurled, or notched. However, sheath handle  202  may have a smooth surface, so long as a physician may hold and guide sheath  200 . 
     Sheath housing  204  is radially coupled to sheath handle  202  and axially coupled to sheath body  206 . Sheath housing  204  is tubular, such that rod housing  104 , from  FIG. 1  may extend into it. However sheath housing  204  is closed on one end. Sheath housing  204  may be 3.5 centimeters in length and 5.5 millimeters in width, although other lengths and widths may be used. However, sheath housing  204  must be longer and wider than rod housing  104  so that rod housing  104  may be inserted into sheath housing  204 . Sheath housing  204  preferable is square in shape; however it may be other shapes (e.g. circular, hexagonal, octagonal), so long as it is the same shape as rod housing  104 . Sheath housing  204  may be made of any rigid material, such as stainless steel. 
     Sheath body  206  is substantially straight. Sheath body  206  preferable is circular in shape; however it may be other shapes (e.g. square, hexagonal, octagonal). Sheath body  206  may be 13 centimeters in length, but may also be shorter or longer. Sheath body  206  is typically shorter than rod body  106  from  FIG. 1 . Sheath body  206  may be made of an opaque plastic material or a metal, e.g. stainless steel, so that it is visible in x-rays and during fluoroscopy and so that it is rigid. Sheath body  206  is axially coupled to sheath housing  204  and radially coupled to sheath handle  202 . Sheath body  206  is a hollow tube. Sheath body  206  may have a diameter of 2 millimeters, but other diameters may be used. However, sheath body  206  preferably has a diameter larger than rod body  106 . from  FIG. 1 , such that rod body  106  may extend through sheath body  206 . 
       FIGS. 2   b  and  2   c  show different cross sectional views of sheath  200 , in accordance with various embodiments of the invention.  FIG. 2   b  is a cross sectional view from the rear of sheath  200  longitudinal to sheath body  206 . As can be seen, sheath housing  204  is coupled to sheath handle  202  and is a hollow tube such that rod housing  104 , from  FIG. 1  may be inserted.  FIG. 2   c  is a cross sectional view of sheath  200  from its front longitudinal to sheath body  206 . Sheath housing  204  is closed at the front end and coupled to sheath body  204 . 
       FIG. 3  shows a detailed view of rod  100  and sheath  200  in combination, such that rod body  106  is fully disposed within the sheath body  206 , labeled vascular access device  300 , which may be used in assisting in making an insertion on a patient from inside the patent, in accordance with various embodiments of the invention. Rod body  106  is inserted into sheath housing  204 . Rod body  106  is then pushed the entire length of sheath body  206  until distal end  108  is near the end of sheath body  206 . Distal end  108 , while curved, is bendable, and thus capable of being inserted into the tubular sheath body  206 . Rod housing  104  is then inserted into sheath housing  204 . 
     In  FIG. 4 , rod handle  102  has been pushed forward against sheath handle  202  so that the distal end  108  of rod body  106  exits sheath body  200 . Rod handle  102  is pushed so that rod body  206  and rod housing  204  slide longitudinally through sheath  200  until rod handle  102  is prevented by sheath handle  202  and sheath housing  204  from moving any further. Once distal end  108  (which normally is curved) reaches the end and exits sheath body  206 , distal end  108  immediately returns to its original curved shape because sheath body  206  will no longer be asserting a force against distal end  108  to keep distal end  108  straight. Thus, at this point, distal end  108  will be radially curved approximately 90 degrees from the longitudinal axis of the rest of rod body  106  and sheath body  206 . 
       FIGS. 5   a  and  5   b  illustrate an exemplary technique in which an embodiment of the medical device is being used on patient  500 , in accordance with various embodiments of the invention. While exemplary  FIGS. 5   a  and  5   b  depict the combination of rod  100  and sheath  200  being used in patient  500 &#39;s arm  502 , the combination may be used anywhere in patient  500 .  FIG. 5   a  shows patient  500  with vascular access device  300  in which the rod body  106  is fully disposed within the sheath body  206 . Rod body  106 , entirely disposed within sheath body  206 , is inserted through an insertion  506  into a blood vessel  504 . Vascular access device  300  is then pushed, using sheath handle  202 , as far into arm  500  as desired for a second insertion. 
     In  FIG. 5   b , at the point in which a second insertion is desired, rod handle  102  is pushed forward toward sheath handle  202  thereby forcing rod housing  104  and rod body  106  to move longitudinally with respect to sheath  200 . By forcing the rod handle  102  and sheath handle  202  together, distal end  108  of rod body  106  exits sheath body  206  and immediately returns to its original curved shape, thereby puncturing the skin in arm  502  to make second insertion  508 . Distal end  108  punctures arm  502  in the same direction as rod handle  102  extends axially from rod housing  104 . 
     Some of these embodiments allow a physician to make a second insertion on a patient from within the patient himself/herself thereby allowing the physician to gain vascular access to the patient in a much more efficient manner than having to make the second insertion from outside the patient (which may be difficult due to location and size of the patient&#39;s extremities). Because the rod body  106  is hollow, a wire may be threaded through it, allowing the physician the capability of easily guiding and inserting a second sheath in the opposite direction in order to make the access functional. 
       FIG. 6  shows an illustrative flow diagram of method  600  implemented in accordance with embodiments of the invention. Method  600  comprises, in block  602 , making an insertion in a patient. This insertion point is preferably large enough in diameter to enable sheath body  206  from  FIG. 2  to be inserted into the patient. The method continues in block  604  with insertion of rod body  106  fully disposed within sheath body  206  from  FIG. 3 , through the insertion point and pushed up the patient&#39;s arm until the end of sheath body  206  is at the desired location of a second insertion. Rod body  106  is fully enclosed within the sheath body  206  during this step. 
     Method  600  also comprises, in block  606 , pushing rod handle  102 , from  FIG. 1 , thereby forcing rod housing  104  and rod body  106 , from  FIG. 4 , to slide longitudinally with respect to sheath body  206 , from  FIG. 4 . At the point that rod body  106 , including distal end  108 , from  FIG. 1 , reaches the point where it is curved, distal end  108  immediately returns to its original curved shape, thereby puncturing the skin in the patient&#39;s arm to make a second insertion. 
     The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.