Abstract:
Disclosed is a catheter having a flexible tube and a sharpened needle secured to the catheter at its distal end. The catheter does not require a separate sharpened instrument to enable insertion into an anatomical passageway. The sharpened needle of the catheter remains disposed within an anatomical passageway during treatment. Also disclosed is a catheter assembly comprising the catheter and a safety inserter. The safety inserter has a blunt end and facilitates the insertion of the catheter by providing a mechanism to urge the sharpened needle of the catheter into an anatomical passageway. Also disclosed is an improved needle tip which minimizes trauma to an anatomical passageway. Also disclosed are methods of using and forming the catheter, catheter assembly and needle tip.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an improved catheter, and more particularly to an improved catheter which provides an increased viable lifetime and also minimizes potential trauma to the patient and the possibility of accidental needle contact with the medical practitioner. 
     Catheters are used for introducing fluids into an anatomical passageway of a patient undergoing treatment. Typically, a catheter is inserted into the anatomical passageway, such as a blood vessel. The catheter is then connected to an administration line from which fluids are introduced into the patient&#39;s vascular system through the catheter. Alternatively, catheters may be placed directly into tissue of a patient, such as a muscle or organ so that a fluid medication may be administered directly to a specific site asystemically as is well understood by those of skill in the art. 
     There are various methods of inserting a catheter into an anatomical passageway. These methods typically involve the use of a sharpened metal needle in conjunction with the catheter. In one such method the metal needle defines a lumen. The metal needle is inserted into the patient&#39;s anatomical passageway. Once the needle is in place, the catheter is introduced through the lumen and into the passageway. This type of catheter system is known as a through-the-needle system. Once the catheter is inserted, the needle is removed. This requires the medical practitioner to pull the needle with its sharp edge out of the patient and guide it over or along the catheter until it is removed. 
     Another type of catheter system is the over-the-needle system. In such a system, a catheter is placed over a rigid needle. The needle and catheter are simultaneously inserted into the patient&#39;s anatomical passageway. Thereafter, the needle is withdrawn from the interior of the catheter, leaving the catheter disposed within the patient. 
     A common problem associated with many over-the-needle catheters is that they tend to travel axially away from the tip of the needle and thus collapse during the insertion procedure. The patient&#39;s skin and tissue tend to resist the introduction of a catheter and push the distal tip of the catheter body backward. The catheter body thus wrinkles in an accordion or bellows-like manner over the needle as the distal end of the catheter travels backward toward the proximal end thereof while the needle is urged through the skin and tissue. This tendency of the catheter to wrinkle results from urging the catheter into the patient by applying a force to a separate needle as opposed to the catheter. Currently, virtually all over-the-needle catheters are formed of a single thermoplastic material such as polyvinylchloride (PVC), Teflon® polyurethane or the like, which provides stiff columnar strength during insertion. The catheter also remains relatively stiff when disposed within an anatomical passageway. Such stiffness traumatizes the walls of the anatomical passageway and typically requires removal of the catheter from the passageway or vessel in two days or less. 
     An over-the-needle catheter is described in U.S. Pat. No. 5,533,988, issued on Jul. 9, 1996 to Dickerson et al. and entitled “Over-The-Needle Catheter”. The catheter includes a flexible body and a hardened tip at the distal end. The hardened tip forms an abutment at the distal end of the catheter. A rigid needle extends within the catheter during the insertion process. The rigid needle engages the abutment in an attempt to prevent the catheter body from collapsing during the insertion process. The hardened tip may comprise a metal, among other materials. Optionally, the tip may comprise a plastic material which softens upon contact with moisture or upon reaching a temperature approximately equal to the patient&#39;s body temperature. 
     A significant disadvantage of both the prior art through-the-needle and over-the-needle systems is that a sharpened needle must be removed once the catheter has been inserted into the patient. Removal of the sharpened needle undesirably exposes both the patient and the medical practitioner to accidental contact with the needle, a continuing problem in view of the highly contagious and/or fatal nature of such diseases as AIDS and Hepatitis A. Removal of the sharpened needle with the catheter in place also presents the problem of damage to the catheter itself. 
     Certain modifications have been made to minimize the possibility of accidental contact of patients or medical practitioners with the needle. One such modification is described in U.S. Pat. No. 5,683,370, issued Nov. 4, 1997 to Luther et al. entitled “Hard Tip Over-The-Needle Catheter and Method of Manufacturing the Same.” The catheter assembly includes an introducing needle which includes a cylindrical protective guard or sheath which is slidably advanced over the sharp tip of the needle after the catheter is inserted and the needle is removed from the patient. 
     However, current devices and methods still require some action by the medical practitioner to remove and dispose of a sharpened needle immediately after inserting the catheter. The timing of this procedure presents drawbacks. Often a catheter is inserted at a moment when time is of the essence. For example, the patient may require emergency medical treatment. The risks associated with the removal of such sharp objects therefore could be minimized by waiting until the patient&#39;s treatment is concluded, a time which often involves less haste and less risk to adversely affect a patient&#39;s health. 
     In addition to the above-described drawbacks associated with present catheters, catheters have also exhibited a limited useful lifetime or viability. For example, present intravenous catheters typically need to be removed approximately every forty-eight hours and then a new catheter is inserted into a different area of the passageway to leave the passageway wall intact. Thus, a catheter must be replaced numerous times in even a short hospital stay by a patient which increases the risks of accidental sticks and contamination. Additional drawbacks are present as well. The removal and reinsertion of catheters increases the trauma to the patient&#39;s anatomical passageways, e.g. blood vessels. The frequent replacement of catheters during the course of a patient&#39;s treatment also increases medical costs, in terms of both time and materials. Accordingly, a catheter would ideally remain in place until the patient&#39;s need for treatment with a catheter is completed. Several factors, however, affect how long a catheter may remain viable. 
     The principal reason for the need to frequently remove and replace a catheter relates to the trauma it causes to the patient&#39;s anatomical passageways such as blood vessels. The trauma may be caused by movement of the patient and/or the portion of the catheter assembly located outside the patient. For example, with regard to an intravenous catheter such external movement is translated to the portion of the catheter located within the patient&#39;s vein and causes the catheter to press against the inside wall of the vein. Such pressure may lead to damage to the inner walls of the patient&#39;s vein or even internal bleeding. The flexibility of a catheter affects the degree to which it presses against the inside of the vein. Although catheters are generally flexible, they have not heretofore been flexible enough to alleviate the problem associated with a catheter pressing against the inside of a patient&#39;s anatomical passageway. 
     Another problem associated with catheters relates to undesirable clotting of blood sometimes associated with certain materials of construction. Depending upon the material of construction of the catheter, blood may form clots when it is drawn up into the catheter. One such material which sometimes causes blood to clot is Teflon®. Although the flow of fluids is typically from the catheter into the patient, the flow sometimes reverses. For example, when an instrument is removed from the fluid communication line connected to the catheter, it may result in a small decrease in pressure within the catheter thereby causing fluid to back up into the catheter from the patient&#39;s vascular system. When the fluid within the tip of the catheter includes blood it may sometimes clot within the Teflon® catheter. Once flow is returned to normal, the clotted blood may be introduced back into the patient&#39;s vascular system. This can lead to various problems. Because the tip of the catheter remains in contact with the blood when the catheter is disposed within a blood vessel, the material of construction of the inner portion of the catheter tip often plays a significant role in the degree of undesirable clotting. 
     The needle tip used in connection with the insertion of catheters, whether it be over-the-needle or through-the-needle systems, is typically formed by an oblique angle cut at the end of a hollow tube or cannula. While a needle formed in such a manner is highly effective for insertion, it can sometimes pass entirely through an anatomical passageway such as a blood vessel or can damage the opposing wall of the passageway during the insertion process. The degree to which such deleterious effects can be avoided depends almost entirely on the skill of the medical practitioner performing the insertion. Moreover, when the needle tip is to remain within the passageway for an extended period during treatment, such conventional needle tips may increase the possibility of trauma to the inside surface of the passageway depending upon the particular application. Therefore, a new catheter with a safety inserter is needed by those skilled in the art to increase safety of patients and healthcare workers alike. 
     SUMMARY OF THE INVENTION 
     The present invention provides a catheter comprising a flexible tube with a sharpened needle tip permanently secured to a distal end of the catheter to facilitate insertion of the catheter into a patient&#39;s anatomical passageway. The sharpened needle tip secured to the catheter remains within the patient&#39;s blood vessel during treatment. As a result, the invention does not require that a separate sharpened needle be inserted with the catheter and then removed immediately after the catheter is properly positioned. 
     Another feature of this invention is that it provides a catheter with increased flexibility to minimize trauma to the interior of an anatomical passageway such as a blood vessel, which increases the time period during which the catheter remains viable within the patient, and also increases the length of catheter which can be maintained within the anatomical passageway. The flexibility of the tube allows the needle tip to be flow directed towards the center of the vessel thereby minimizing trauma to the vessel and increasing the time period during which the catheter remains viable. 
     An additional advantage of the preferred embodiment of this invention is that it provides a catheter tip formed of a material which minimizes the clotting of blood which may back up into the catheter. 
     The preferred embodiment uses a retaining material adjacent the distal end of the flexible tube and extending around a portion of the circumference of the sharpened needle tip to secure the needle tip to the distal end of the catheter. To provide further support to the needle, one or more cavities are advantageously formed in the outer surface of the needle, which are filled with the material of the flexible tube, the retaining material, or both. Additional securement is provided by the melting and mingling of the two plastic materials comprising the flexible tube and retaining material when the needle tip is affixed to the distal end of the catheter. 
     A further feature of the preferred catheter assembly apparatus and method is that insertion of the catheter into a blood vessel or the like does not require a separate sharpened inserter to be used with the catheter. The catheter assembly comprises a catheter and a safety inserter. The safety inserter may be removably engaged within the catheter. Preferably, the inserter comprises a base portion and a distal end portion. The proximal end of the safety inserter is sized to accommodate a hydrophilic filter plug and/or a luer tip of a syringe. The distal end portion is sized to fit within the sharpened needle tip. The base portion is sized to fit within the flexible tube and to abut an annular shoulder formed by the proximate edge of the needle tip. Preferably, this inserter has a blunt distal end since the sharpened needle tip secured to the distal end of a flexible tube enables insertion of the catheter into the patient&#39;s anatomical passageway such as a blood vessel. 
     In accordance with a further aspect of the present invention, the safety inserter has a closed distal end and corresponds to the shape of the needle tip at the distal end of the catheter. Such a catheter is particularly useful as an epidural catheter or a catheter to access implanted ports wherein no flashback is required. 
     In accordance with a further aspect, the invention provides a needle tip and method of forming the same wherein the point of the needle tip is substantially aligned with a central axis of the lumen defined by the needle tip or cannula from which it was derived. The improved needle tip minimizes the risk of injury to walls of an anatomical passageway. 
     Further features and advantages of the present invention will become apparent to those of skill in the art in view of the detailed description of preferred embodiments which follow, when considered together with the attached claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a catheter assembly of the present invention, comprising a safety inserter and a catheter. 
     FIG. 2 is a perspective view of a catheter of the present invention. 
     FIG. 3 is a cross-sectional view of the catheter. 
     FIG. 4 is a perspective view of an alternative embodiment of the distal end of the catheter. 
     FIG. 5 is an enlarged cross-sectional view of the distal end of a catheter of the present invention showing a preferred mechanism for securing the sharpened needle at the distal end of the catheter. 
     FIG. 6 is a cross-sectional view of a safety inserter of the present invention. 
     FIG. 7 is a perspective and an enlarged cross-sectional view of the distal end of the catheter assembly wherein the safety inserter is inserted into the catheter. 
     FIG. 8 is a perspective view of the improved sharpened needle tip of the present invention. 
     FIG. 9 is an enlarged cross-sectional view of the improved sharpened needle tip of the present invention. 
     FIG. 10 is an enlarged cross-sectional view of the distal end of the catheter assembly wherein the safety inserter has a closed distal end. 
     FIG. 11 is an enlarged cross-sectional view of the distal end of the catheter assembly wherein the safety inserter has a closed distal end corresponding to the internal configuration of an epidural needle tip. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 depicts the improved catheter assembly  10  of the present invention. The catheter assembly  10  comprises a safety inserter  12  and a catheter  14 . 
     Referring to FIGS. 2 and 3, the catheter  14  comprises a flexible tube  16  defining a lumen  18  therethrough. A sharpened needle tip  20  is secured to a distal end of the flexible tube  16 . A hub  22  is formed at a proximal end of the catheter  14 . The hub  22  facilitates connection of the catheter  14  with an administration line (not shown) to provide for the communication of fluids through the catheter  14 , as will be easily understood by those skilled in the art. 
     The flexible tube  16  advantageously is preferably formed of a soft thermoplastic material. Preferably, the flexible tube  16  is formed of a material having a hardness value between 50 and 90 Shor A, more preferably between 65 and 85 Shor A, and most preferably approximately 70 Shor A. In a preferred embodiment, the flexible tube  16  is formed of polyurethane. A suitable polyurethane is sold under the tradename Carbothane™ by Thermedics Corporation of Woburn, Mass. and has a hardness value of approximately 70 Shor A. 
     The soft flexible tube  16  minimizes the trauma to the internal surface of the anatomical passageway into which the catheter  14  is placed. Thus, movement of the patient and/or the catheter  14  located outside the patient is not substantially translated to movement of the portion of the flexible tube  16  within the patient&#39;s anatomical passageway. When the catheter  14  is disposed within an anatomical passageway such as a blood vessel, the flexibility of the tube  16  allows the catheter  14  to be flow directed to the center of the blood vessel, the area of highest velocity flow which is sometimes referred to as the “hemodynamic center” of the vessel. The minimization of trauma to the internal surface of the blood vessel allows the catheter  14  to remain viable for longer periods than heretofore feasible. When used intravenously, the catheter  14  of the present invention may remain viable for a treatment period in excess of seven days, and preferably in excess of ten days. In some instances the catheter  14  may remain viable for two weeks or more. The increased viability of the catheter  14  has many advantages. For example, it decreases the number of times a patient will need to be “stuck” due to the removal and reinsertion of a catheter  14  during the course of treatment. In addition, it minimizes the number of times medical practitioners are exposed to sharp needles and the potential for accidental sticks. It also decreases the cost, in terms of both time and materials, associated with the use of multiple catheters during the course of treatment. The flexibility of the tube  16  also allows for an increased length of tube to be extended within the patient&#39;s anatomical passageway as the application may require. 
     Flexible tubes containing flexible interwoven wires in the tubular wall such as manufactured by H.V. Technologies of Trenton, Ga. are available. These tubes have the advantage of high strength, high radiopacity and high flow rates because of decreased wall thickness. Walls of only 0.003 inches are possible. 
     The size of the flexible tube  16  varies by application. Generally, the outside diameter of the flexible tube  16  will range from approximately 0.02 to 0.08 inches. A flexible tube  16  of a preferred embodiment for intravenous use has an outside diameter of 0.035 inches, a wall thickness of 0.005 inches, and thereby forms a lumen of 0.025 inches in diameter. 
     Referring to FIGS. 3,  4  and  5  a sharpened needle tip  20  is secured to a distal end of the flexible tube  16 . In one aspect of the invention the sharpened needle tip  20  is formed by cutting the end off a conventional sharpened cannula. The cannula comprises an elongated tube defining a lumen and having an oblique angled cut to form its sharp end. 
     The needle tip  20  therefore has an inner surface  24  defining a lumen  28 . The proximal end of the needle tip  20  forms a short tube  30  (FIG.  3 ). The distal end of the needle tip  20  has a piercing point  26 . 
     Preferably, the sharpened needle tip  20  is formed of a metal. One suitable metal is a 300 Series stainless steel. The needle tip  20  may be a suitable length for the application at issue. Preferably, it is approximately 0.1 to 0.25 inches in length. The outside diameter of the needle tip  20  corresponds to the inside diameter of the flexible tube  16  of the catheter  14 . Preferably, the diameter of the lumen  28  defined by the inner surface of the needle tip  20  is approximately 60-90% of the outside diameter so as to maintain the structural integrity of the needle tip  20  during use. 
     At least a portion of the proximal end of the needle tip  20  extends into the distal end  17  of the flexible tube  16 . In a preferred embodiment wherein the needle tip  20  has length of 0.23 inches, approximately 0.13 inches extend within the flexible tube  16 . Referring to FIG. 5, preferably the outer surface  32  of the needle tip  20  is adjacent the inner surface  34  of the flexible tube  16 . The proximal edge of the needle tip  20  forms an annular shoulder  36  within the flexible tube  16 . The lumen  28  of the sharpened needle tip  20  is in fluid communication with the lumen  18  defined by the flexible tube  16 . Preferably, the lumen  28  of the sharpened needle tip  20  is coaxial with the lumen  18  defined by the flexible tube  16 . 
     Referring to FIG. 3, the proximal end of the flexible tube  16  is attached to a hub assembly  22  and is in fluid communication therewith. The hub assembly  22  facilitates connection of the catheter  14  to a communication line from which fluids are administered to a patient. Any suitable hub assembly  22  may be utilized as is understood in the art. 
     As shown in FIG. 3, in a preferred embodiment, the catheter  14  further comprises a strain relief  38  disposed around the flexible tube  16 . The strain relief  38  facilitates the attachment of the flexible tube  16  to the hub  22  and also provides additional structural integrity to the flexible tube  16 . This is useful if the catheter  14  needs to clamped. For example, after the catheter  14  is inserted into a patient, a hemostasis clip may be applied to prevent the flow of fluids through the catheter  14  while an administration line is connected. By applying the clip to the outer surface of the strain relief  38 , it will close the lumen  18  of the flexible tube  16  without creating the risk of damaging the flexible tube  16  which is in fluid communication with the patient&#39;s anatomical passageway. In a preferred embodiment, the flexible tube  16  and strain relief  38  are fixed within a hub  22 . Alternatively, they can be fixed to an outer surface of a hub  22  or other apparatus so long as fluid communication is maintained through the catheter  14  and hub  22 . 
     Referring to FIGS. 1 and 6, the safety inserter  12  of the catheter assembly  10  comprises a base  40 , a body portion  42  and a distal portion  44 . In a preferred embodiment, the base  40  facilitates handling of the catheter assembly  10  during insertion of the catheter  14  and subsequent removal of the inserter  12 . The base  40  therefore preferably includes a surface  43  for gripping during the insertion and removal process. The base  40  further defines a flashback chamber  46 , which can also be configured to accommodate a luer. As shown in FIG. 1, a hydrophilic plug  11  is inserted into the flashback chamber which facilitates venting of air from the flashback chamber  46  while also preventing leakage of blood or fluids therefrom. The base  40  of the inserter is adapted to engage the hub  22  of the catheter  14 . In a preferred embodiment, the base  40  forms a friction fit with the hub  22 . 
     Referring to FIGS. 6 and 7, the body portion  42  of the safety inserter  12  is sized to fit within the lumen  18  of flexible tube  16  of the catheter  14 , but not within the lumen  28  formed by the sharpened needle tip  20 . The distal end portion  44  of the safety inserter  12  is sized to fit within the lumen  28  formed by the sharpened needle tip  20  of the catheter  14 . The distal edge  47  of the distal end portion  44  of the inserter  12  need not be sharp, and is preferably blunt to avoid the possibility of damage to the catheter  14  or the risk of needle stick injuries. 
     In a preferred embodiment, the body portion  42  of the safety inserter  12  is formed by a cannula  48  having an outside diameter corresponding to the diameter of the lumen  18  defined by the flexible tube  16  of the catheter  14 . A smaller cannula  50  is fixed within the larger cannula  48 . The small cannula  50  extends out from a distal end of the large cannula  48  to form the distal end portion  44  of the safety inserter  12 . The outside diameter of the smaller cannula  50  corresponds to the inside diameter of the sharpened needle tip  20  and the inside diameter of cannula  48 . Alternatively, the safety inserter  12  may be manufactured as a unitary piece. 
     When the safety inserter  12  is engaged within the catheter  14 , the distal edge  53  of the large cannula abuts the annular shoulder  36  formed at the proximal edge of the sharpened needle tip  20 . In a preferred embodiment, the sharpened needle tip  20  is formed by cutting the sharp end off a sharpened cannula  48 . The remaining cannula is then used as the large cannula  48  of the safety inserter  12 . This assures that the needle tip  20  and large cannula  48  are properly sized. 
     The lumen  49  defined by the large and small cannulas  48 ,  50  may be in communication with the flashback chamber  46  of the base  40 . In one embodiment, the small cannula  50  extends into the flashback chamber  46 ; however, the cannula  50  may terminate distal the flashback chamber  46  as will be easily understood. 
     The sharpened needle tip  20  may be secured to the flexible tube  16  in any suitable manner. A particularly effective means of attachment comprises the use of a radio frequency (RF) welder. Application of the RF energy heats the flexible tube  16  material of the catheter  14  and causes it to adhere to the sharpened needle tip  20 . Additionally, it causes the simultaneous melting and some commingling of the two plastic materials forming the flexible tube  16  and retaining material  52  to further promote the securement of the needle tip  20 . 
     In a preferred embodiment, the catheter  14 , as shown in FIG. 5, further comprises a retaining material  52  adjacent the distal end of the flexible tube  16  and disposed around at least a portion of the outer surface of the needle tip  20 . Preferably, the retaining material  52  forms an annular ring surrounding the outer circumference of the needle tip  20 . A mandrel (not shown) is preferably placed within the flexible tube  16  and the needle tip  20  during the attachment process. Alternatively, a safety inserter  12  of the present invention can be used for this purpose. The retaining material  52  and a portion of the flexible tube  16  are then heated with the RF welder. Pressure may also be applied to the outer surface of the flexible tube  16  and the retaining material  52 . The retaining material  52  adheres to the needle tip  20  and tube  16  during the welding process. Likewise, the tube  16  adheres to the needle tip  20  during welding. 
     The retaining material  52  preferably comprises a plastic having a hardness greater than the material forming the flexible tube  16 . Preferably the retaining material is a polyurethane. In one preferred embodiment the retaining material is a polyurethane having a hardness value of approximately 99 Shor A. The retaining material may, of course, be of any other hardness. 
     In another aspect of the invention, a first set of one or more cavities  54   a, b  are formed in the outer surface  32  the needle tip  20 . The cavities  54   a, b  extend from the outer surface  32  of the needle tip  20  toward the inner surface  24 . Preferably, the cavities extend from the outer surface  32  to the inner surface  24  forming a hole through the outer circumference of the needle tip  20 . During the attachment process, the needle tip  20  is positioned within the distal end of the flexible tube  16  with the first set of one or more cavities  54   a, b  located distal the end of the flexible tube  16 . The retaining material  52  is formed in an annular shape around the circumference of a portion of the needle tip  20  extending beyond the flexible tube  16  and covering the holes  54   a,b . A mandrel is placed within the flexible tube  16  and needle tip  20 . The retaining material  52  is heated with the RF welder. In its molten state the retaining material  52  fills the first set of one or more cavities  54   a, b  to further secure the needle tip  20  to the flexible tube  16 . In addition, the retaining material  52  adheres to the tube  16 . 
     In another aspect of the invention, a second set of one or more cavities are formed in the outer surface  32  of the needle tip  20 . Preferably, the cavities  56   a, b  extend from the outer surface  32  to the inner surface  24  forming a hole through the outer circumference of the needle. Alternatively, the cavities may be indentations that do not extend through the needle tip  20 . During the attachment process, the needle tip  20  is positioned within the distal end of the flexible tube  16  with the first set of one or more attachment cavities  54   a, b  located beyond the end of the flexible tube  16 , and the second set of one or more attachment cavities  56   a, b  located within the lumen  18  defined by flexible tube  16 . The retaining material  52  is formed in an annular ring around the circumference of the needle tip  20  as described above. Another advantage of the invention is the harder (99 Shor A) material can be formed to eliminate any transition shoulder between the point of the needle tip  20  and the flexible tube  16  thereby minimizing trauma during insertion. An RF welder is applied to the retaining material  52  and flexible tube  16  as described above. The first set of one or more cavities  54   a, b  is filled with the retaining material  52 . The material of the flexible tube  16  fills the second set of one or more cavities  56   a, b.    
     The cavities  54 ,  56  can be any suitable size, depending upon the size of the needle tip  20  and the corresponding flexible tube  16 . In a preferred embodiment the cavities  54 ,  56  form holes in the needle tip  20  having a diameter of 0.005 inches. A sufficient number of holes may be used, but not so many that would interfere with the structural integrity of the needle tip  20 . In a preferred embodiment of the invention, the first and second sets of cavities  54 ,  56  each comprise two holes. It should be understood that the tube  16  retaining material  52  and needle tip  20  may be adhered without the use of holes or indents. Moreover, the tube  16  may be adhered to the needle tip  20  without the use of a retaining material  52  as will be understood by those skilled in the art. For example, the tube  16  may be RF bonded directly to the needle tip  20  and the distal end  17  of the tube may be sloped toward the needle tip  20  in the bonding process to eliminate a shoulder which may harm a vessel wall upon insertion of the catheter  14  in a passageway of a patient. 
     Of course, the needle tip  20  may be provided with external projections which communicate with indents or holes in the flexible tube  16  and/or retaining material  52  to add in securing the tip  20  to the tube  16  and/or material  52  as will be easily understood by those of skill in the art. 
     FIGS. 8 and 9 illustrate another embodiment of the invention wherein an improved needle tip  58  has been adapted to minimize trauma to the interior of the anatomical passageway in which it is inserted. The conventional needle tip  20  shown, for example, in FIG. 5 has a piercing point  26  at its most distal end. The piercing point  26  is aligned with the outer surface  32  of the short tube  30  forming the proximal end of the needle. In the embodiment wherein the needle tip  20  is formed by cutting an end off a sharpened cannula, the point  26  is in a place defined by a portion of the wall of the cannula. The improved needle tip  58  of this further aspect of the invention has a piercing point  60  substantially aligned with a central axis  62  of the lumen  64 . Preferably, the improved needle tip  58  is formed by bending a conventional needle tip  20  so that the piercing point  60  of the needle tip  58  is so aligned. Alternatively, the needle can be manufactured in the desired configuration. By providing the needle point  60  substantially along the central axis  62  of the lumen  64  of the needle tip  58 , the risk of the needle tip  58  piercing the opposing wall of a passageway or vessel of a patient is significantly reduced, both during the insertion process and while the catheter  14  is disposed within a patient&#39;s anatomical passageway. In practice, a healthcare worker sometimes inserts a standard needle tip  20  too far, so that it enters the vessel and then pierces the opposing wall of the vessel. Upon withdrawal of the needle tip, internal bleeding occurs. By placing the point  60  along the central axis  62 , the risk of piercing the opposite vessel wall is significantly reduced because the catheter is typically inserted into the vessel at an acute angle to the longitudinal axis of the vessel, as will be easily understood by those of skill in the art. Similarly, the point  60  of needle tip  58  will naturally be less likely to contact the inside wall of an anatomical passageway in which it is disposed thereby reducing the risk of trauma to the patient. 
     Having thus described the construction of certain preferred embodiments of the apparatus of the present invention and the associated method of making the same, a preferred treatment method utilizing the apparatus of the invention is described. The safety inserter  12  is initially placed within the catheter  14 . The distal end portion  44  of the safety inserter  12  extends within the lumen  28  defined by the needle (FIG.  7 ). The distal edge  47  of the distal end portion  44  extends sufficiently far into the needle tip  20  to provide support during insertion but not so far that the blunt end  47  of the inserter will interfere with the piercing point  26  of the needle tip  20 . The body portion  42  of the inserter extends within the flexible tube  16  of the catheter  14 . The distal edge  53  of the outer cannula  48  forming the base portion  42  preferably abuts the proximal edge  36  of the needle tip  20  to allow the practitioner to urge the catheter  14  into a patient&#39;s anatomical passageway by applying force to the inserter  12 , which is translated to the needle tip  20 . In one preferred application the catheter  14  is urged into a patient&#39;s vein to provide intravenous treatment to the patient. 
     Once the catheter  14  is properly placed within the patient&#39;s anatomical passageway, a homeostasis clip or suitable device is applied to close the flexible tube  16 . Preferably the clip is applied to the strain relief  38 . The catheter  14  is held in place while the inserter  12  is removed. The blunt inserter  12  is eventually discarded. The hub  22  of the catheter  14  may then be connected to a fluid communication line such as a standard administration set. The catheter  14 , including the sharpened needle tip  20 , remains disposed within the patient&#39;s anatomical passageway. Fluid communication is established through the catheter  14  wherein fluids are infused into or withdrawn from the patient by removal of the clip. Preferably, the catheter  14  remains in place during the entire period in which the patient is treated with a catheter  14 . Thereafter, the catheter  14  is removed. Because the sharpened needle tip  20  is disposed at the end of a flexible tube  16  as opposed to a rigid cannula as in prior art inserters, the risk of accidental sticks is minimized. Furthermore, because the catheter  14  is often removed at the conclusion of treatment, there is typically a lesser degree of haste involved, thereby allowing the medical practitioner to more easily exercise the proper degree of care in removing and discarding the needle tip  20 . 
     FIGS. 10 and 11 illustrate further aspects of the invention, which are particularly useful for applications which do not require a flashback. These include epidural catheters and catheters used to access implanted ports such as described in U.S. Pat. No. 5,403,283 issued on Apr. 4, 1995 to Luther and entitled “Percutaneous Port Catheter Assembly and Method of Use”. The inserters  61  and  63  do not include a lumen through their length and preferably are closed at their distal end. This aspect of the invention is particularly suitable for epidural catheters since the catheter is ideally formed so as not to introduce tissue into the epidural space. An open lumen at the distal end of the catheter  14  may cause tissue to be carried into the epidural space during the insertion process. 
     Referring to FIG. 10, the inserter  61  is sized to fit within the lumen  18  defined by the flexible tube  16  and the lumen  28  formed by the sharpened needle tip  20 . The distal end  62  of the inserter  61  preferably corresponds roughly to the shape of the needle tip  20 . The distal end  62  of the inserter is preferably blunt to prevent the inserter  61  from piercing or penetrating the skin of a person. The end of the inserter may be sand-blasted to provide the dull or blunted distal end  62 . 
     FIG. 11 illustrates an embodiment that is particularly suitable for use in epidural applications. The needle tip  65  has a distal end  69  configured in the Toughy or Hustead configuration of conventional epidural needle points. The insert  63  corresponds roughly to the shape of the needle tip  65 , and is preferably dulled or blunted at its distal end  68 . 
     Although the present invention has been described in terms of certain preferred embodiments, other embodiments of the invention will become apparent to those of skill in the art in view of the disclosure herein. Accordingly, the scope of the present invention is not intended to be limited by the foregoing, but rather by reference to the attached claims.