Step-down catheter

Abstract: The invention relates to a catheter (100) and a method of placing a catheter that includes a substantially tubular body portion (110) having an outside diameter no less than the inside diameter of an opening in a catheter introducer (160) adapted to insert a portion of the catheter into a patient's body. The catheter (100) also includes a transition member portion (130) adjacent to a first end of the tubular body portion (110). The transition member portion (130) has an outside diameter that is less than the outside diameter of the tubular body portion and less than the inside diameter of the opening in the catheter introducer (160). The invention contemplates that the transition member (130) can be coupled to the end of the tubular body portion (110), integrally formed with the body portion, or extends from the end of body portion and be removable from the a distal end of the body portion. A benefit of the catheter including a transition member portion (130) having an outside diameter that is less than the inside diameter of the opening in the catheter introducer (160) is that it allows a means for inserting a through the introducer catheter which is larger than the inside diameter of the introducer. This provides the benefit of an over the needle insertion with regard to needle size, but allows for a larger catheter to be placed in the vein by the subsequent removal of the introducer once the transition member is placed in the vein.

Description: BACKGROUND OF THE INVENTION Field of the Invention The invention is generally directed to medical catheters and catheter kits for placement of catheters into a patient. Description of Related Art Catheters are commonplace in the medical field, finding importance in a variety of uses. The term "catheter" is commonly used to identify a tubular instrument that is inserted into a body cavity or orifice, naturally or surgically opened. Vascular catheters, for example, come in many different forms and have many different uses. A vascular catheter typically consists of a hub and tubing or cannula through which fluid flows. The hub may include a flash chamber that allows the individual placing the catheter to see blood in the flash chamber that indicates the catheter has entered a vein. There are different types of vascular catheters. The primary types include the short peripheral, which is typically placed only a short distance (e.g. 51-76 mm ( 2-3 inches)) in a vein in the hand or arm of the patient. There are also venous catheters that are longer and include a midline catheter that is placed approximately 152-203 mm (6-8) inches in the vein of a patient, and a peripherally inserted central catheter ("PICC") which is placed peripherally, e.g. in the arm of a patient, and fed a significant distance, e.g. to the superior vena cava. Still another type of vascular catheter is the central venous catheter which is typically placed in the internal jugular or subclavien vein, implanted under the skin, tunneled underneath the skin, etc. One common method of placing a vascular catheter in a patient is through an introducer. In this case, an introducer including a needle, is placed in a patient and into a vein. The needle is then removed and the catheter is inserted through the introducer into the vein. A second method of placing a catheter in a patient, often referred to as an Over-The-Needle ("OTN") insertion, places the catheter cannula directly over the needle used to introduce the catheter into the vein. The needle is typically connected to a wire or stylet that allows the needle to be removed from the distal or hub end of the catheter cannula once the proximate end of the catheter cannula is placed in the vein. With the needle removed, the catheter is advanced in the vein and placed where desired. The OTN catheter permits the use of a smaller outside diameter needle for a given size outside diameter catheter cannula. The clinical benefit of the OTN approach is the maximization of the size of the catheter placed compared to the size of the needle used. A smaller needle means one can more easily access veins and impart less pain to the patient. Figures 1 and 2 illustrate the different types of vascular catheter introduction methods. Figure 1 illustrates a Through-The-Introducer ("TTI") insertion method and Figure 2 illustrates an OTN insertion method. In the TTI type insertion, an introducer sheath 20 and needle 30 are inserted into the vein of a patient. Once inserted, the needle 30 is removed and the catheter cannula 10 is advanced through the introducer sheath 20. When the catheter cannula is placed through the introducer, the maximum outside diameter of the catheter cannula that is placed is slightly smaller than the inside diameter of the introducer or slightly smaller than the outside diameter of the needle. In Figure 1, for example, at least a 19 gauge needle 30 is needed to place a 20 gauge catheter cannula 10. In the OTN introduction method, a needle 40 is inserted into a patient, the needle 40 being inside a catheter cannula 10 and having a wire or stylet 50 coupled to a hub 60 at the distal end of the catheter cannula 10. Once the needle 40 and a portion of the catheter cannula 10 are inserted into the patient, the needle 40 is removed from the patient by pulling the hub 60 away from the patient. Once the needle 40 is removed, the catheter cannula 10 is advanced to the desired placement in the patient. Figure 2 illustrates that a smaller outside diameter needle, e.g. 22 gauge, may be used to place a larger outside diameter catheter cannula, e.g., 20 gauge. Further catheter devices are disclosed in DE-A-31 07 983 and WO-A-86/01414. DE-A-31 07 983 forms the basis for the pre-characterising portion of claim 1. SUMMARY OF THE INVENTION A catheter, catheter kit, and a method of placing a catheter is disclosed. The catheter of the invention is defined in claim 1 and the catheter kit of the invention is defined in claim 8. It is contemplated that the transition member can be coupled to the end of the tubular body or integrally formed with the body A benefit of the catheter including a transition member portion having an outside diameter that is less than the inside diameter of the opening in the catheter introducer is that it allows a method for placing a TTI catheter which is larger than the inside diameter of the introducer, by first placing the transition member through the introducer. This provides the benefit of OTN insertion with regard to needle size, but allows for a larger catheter to be placed in the vein by the subsequent removal of the introducer once the transition member is placed in the vein. Additional features and benefits of the invention will become apparent from the detailed description, figures and claims as set forth below. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a planar side view of a through the introducer catheter introduction configuration. Figure 2 is a planar side view of an OTN catheter introduction configuration. Figure 3 is a planar side view of a catheter of the invention with a TTI configuration. Figures 4-9 illustrate the method of placing a catheter into a patient wherein the transition member portion of the catheter is integral or coupled to the end of the tubular body portion of the catheter. Figure 10 illustrates a planar cross-sectional view of the transition member of the catheter of the invention taken through line A-A of Figure 9 wherein the transition member expands to substantially match the cross-sectional area of the tubular body of the catheter. Figure 11 illustrates a perspective side view of the catheter of the invention including a transition member wherein the transition member expands to substantially match the diameter of the tubular body of the catheter. Figure 12 illustrates a planar cross-sectional view of the transition member of the catheter of the invention taken through line A-A of Figure 9 wherein the transition member unfolds to substantially match the cross-sectional area of the tubular body of the catheter. Figure 13 is a perspective side view of the catheter of the invention wherein the transition member is folded to reduce the cross-sectional area of that portion of the catheter. Figure 14 illustrates a perspective side view of the catheter of the invention wherein the transition member is in an unfolded state to substantially match the cross-sectional area of the tubular body of the catheter. Figure 15 is a planar side view of a catheter of the invention wherein the transition member portion is transitioned in steps of decreasing diameter or cross-sectional area. DETAILED DESCRIPTION OF THE INVENTION The invention relates to a catheter and a catheter kit, wherein the catheter includes a substantially tubular body and a transition member. The substantially tubular body has an outside diameter no less than the inside diameter of an opening in a catheter introducer adapted to insert a portion of the catheter into a patient's body. The transition member is positioned adjacent a first end of the tubular body. The transition member has an outside diameter that is less than the outside diameter of the tubular body and less than the inside diameter of the opening in the catheter introducer. The catheter is used by placing an introducer into a patient, providing a catheter with a substantially tubular body and a transition member, inserting the transition member through the opening in the body of the introducer, removing the introducer from the patient and placing a portion of the tubular body of the catheter into the patient. In the following detailed description, specific embodiments of the invention are described with reference to particular materials. Numerous specific details are set forth such as specific materials, configurations, and methods of placing a catheter. It will be obvious, however, to one skilled in the art, that these specific details need not be employed to practise the invention. In other instances, well known materials or methods have not been described in detail in order to avoid unnecessarily obscuring the invention. Figure 3 illustrates a planar side view of a catheter configuration of the invention. Figure 3 shows a catheter 100 made up of a substantially tubular body portion 110 and a transition member portion 130. The substantially tubular body portion of cannula 110 is coupled to a hub 120 at the distal end of the catheter cannula 100. The catheter 100 is configured to be placed in a patient through an introducer 160. The introducer is comprised of handles 140 and a sheath 150. The introducer 160 further includes a removable needle 170. To place the catheter 100 in a patient, the introducer 160 and needle 170 are first placed in the desired location, e.g., the vein, of a patient in a conventional manner. Next, the needle 170 is removed from the distal end of the introducer 160, leaving only the introducer sheath 150 in the patient. Next, the catheter of the invention is inserted through the introducer sheath 150 into the vein. As noted, the catheter 100 includes a transition member portion 130 that has an outside diameter that is less than the inside diameter of the opening in the introducer sheath 150. The transition member portion 130 of the catheter 100 is fed into the vein through the introducer 160. Once the transition member portion 130 is securely placed through the introducer 160 and into the vein, the introducer 160 is removed from the patient and peeled apart or divided and separated from the location near the patient as is common in the prior art. It should be evident that the division of the introducer 160 can be accomplished while the introducer 160 is being removed, for example, to accommodate a shorter transition member portion 130. The tubular body portion 110 of the catheter may then be advanced into the patient by following transition member 130 through the opening made by the needle 170 and the introducer sheath 150. To aid insertion of the tubular body portion 110, the tubular body portion 110 optionally includes a tapered leading edge 115 that gradually opens the existing cut made by the needle 170 in the patient's skin. The cut made by needle 170 in a patient is large enough to insert the introducer sheath 150. Therefore it is contemplated that the cut will be large enough to accommodate the tubular body portion 110 of the catheter of the invention. The tubular body portion 110 of the invention has an outside diameter that is no less than the inside diameter of the opening in the catheter introducer 160 or no less than the outside diameter of the needle 170. In one embodiment, the outside diameter or gauge of the tubular body portion 110 of the catheter cannula 100 is approximately the same as the outside diameter of the introducer sheath 150 or the needle 170. In another embodiment, the invention takes advantage of the elastic nature of the skin. The elasticity of the skin allows an opening in the skin, i.e. a needle cut, to stretch approximately 2 gauge sizes to accept an object of a larger diameter than the opening. The invention contemplates, for example, that a cut made by a 22 gauge needle to insert a catheter can accept a 20 gauge catheter using the technique described by the invention. Figures 4-9 illustrate a method of inserting the catheter of the invention wherein the transition member portion 130 of the catheter is integral to or coupled to the end of the tubular body portion 110 of the catheter 100. First, as shown in Figure 4, a needle 170 and introducer 160 including an introducer sheath 150 are placed through the skin 200 of a patient and into a vein 210. Once properly located in the vein 210, the needle 170 is removed from the introducer 160 through the introducer body 140. Next, as shown in Figure 5, the catheter 100 is placed in the vein 210. The catheter 100 of the invention includes a transition member portion 130 with an outside diameter that is less than the outside diameter of the tubular body portion 110 of the catheter and less than the inside diameter of the introducer sheath 150. For example, the invention contemplates that for a 22 gauge introducer sheath, the transition member 130 of the catheter 100 has an outside diameter smaller than the inside diameter of the sheath 150. Once placement of the transition member 130 of the catheter 100 in the vein 210 is secure, the introducer 160, including the introducer sheath 150, is removed from the vein 210 and the skin 200 of the patient as shown in Figure 6. Once the introducer 160 is removed from the skin, Figure 7 illustrates that the introducer is peeled away from the catheter 100. It is to be noted that the introducer 160 may be peeled away from the catheter 100 while the introducer 160 is being removed, for example, to accommodate a catheter 100 with a shorter transition member 130. To facilitate the peeling away and removal of the introducer 160, the introducer handles 140 and sheath 150 may be made of a durable material of varying thickness and a pair of opposed wall portions thinner than the remainder of thc introducer 160. In this manner, the introducer 160 is divided at the opposing thinner side walls as shown in Figure 7. Alternatively, the introducer handles 140 and sheath 150 may be scored or sliced along opposing sides and divided along the scored or sliced section. Similarly, the sheath 150 is made of a sufficiently thin material so that the sheath 150 may be easily separated when the introducer 160 is divided. Once the introducer 160 is removed from the target site and no longer encompasses the transition member 130 of the catheter 100, the catheter 100 is further advanced so that the tubular body portion 110 can be inserted into the skin 200 and the vein 210 of the patient. Figure 8 illustrates the introduction of the tubular body portion 110 into the skin 200 and vein 210 of the patient. The tubular body portion 10 has an outside diameter no less than the inside diameter of the opening in the introducer 160. Taking advantage of the elastic property of the skin 200, the invention contemplates that the tubular portion 110 may be sized approximately 2 gauge sizes larger than the cut made by the needle 170 (and introducer sheath 150). Thus, for a 22 gauge needle 170 opening in the skin 200, the it is contemplated that the tubular body portion 110 of the catheter 100, in one embodiment, has an outside diameter equivalent to a 20 gauge size. The tubular body portion 110 is advanced into the vein to its proper location. Figure 9 illustrates an embodiment of the invention wherein, after the transition member portion 130 of the catheter 100 is inserted in the patient's body fluid, e.g. blood, the transition member portion 130 assumes a lumen with a cross-sectional area substantially equivalent to the cross-sectional area of the lumen tubular body portion 110. In this case, since the entire cannula 100 will have a cross-sectional area equivalent to the lumen of the tubular body portion 110, the fluid flow through the catheter is improved. In other words, the invention contemplates no reduction in flow capacity through the entire length of the catheter cannula. Figures 10-11 illustrate an embodiment wherein the transition member portion 130 expands to substantially match the cross-sectional area of the tubular body portion 110. The transition member portion 130 is made of a material that swells or expands upon exposure to body fluid. Such a material is Aquavene®, a registered trademark of Menlo Care Corporation of Palo Alto, California. Aquavene® is a composite of a hydrogel and an elastomer. This material is described in U.S. Patent Nos. 4,883,699 and 4,911,691, assigned to Menlo Care. Other materials include thermally-activated hydrogel, hydrogel derivatives, hydrophilic polyurethane and certain memory polymers. Figure 10 shows a transition member portion 130 having a lumen of cross-sectional area of diameter 250 that expands to a cross-sectional area with diameter 260 upon exposure to body fluid. The range of expansion of the catheter area is typically at least two gauge sizes. Figure 11 illustrates a perspective side view of the catheter cannula having a lumen of the transition member portion 130 that has expanded to substantially match the cross-sectional area of the tubular body portion 110. Another embodiment of the catheter with a transition member portion that expands, as shown in Figure 9, to a lumen with a cross-sectional area that substantially matches the cross-sectional area of the lumen of the tubular body portion is shown in Figures 12-14. Figures 12-14 illustrate an embodiment wherein the transition member 130 includes a folded state 270 and an unfolded state 280. In the folded state 270, the transition member portion 130 has an area of reduced diameter. In the unfolded state 280, the transition member portion 130 has an outside diameter substantially equivalent to the tubular body portion 110. The folded state 270 is accomplished by longitudinally folding a portion of the transition member 130 inward to reduce the effective outside diameter of the cannula. Figure 13 illustrates a perspective side view of the transition member in the folded state. Figure 14 illustrates a perspective side view of the transition member 130 in the unfolded state with an outside diameter substantially equivalent to the outside diameter of the tubular body portion 110. Figure 15 illustrates an embodiment wherein the transition member portion is transitioned in steps for increased flexibility at the tip of the catheter. In Figure 15, the transition member portion includes the transition member portions of decreasing cross-sectional area 515, 520, and 525, extending from an end of the tubular body portion 500. Once again, it is contemplated that the stepped transition portions 515, 520, and 525 may be integrated with or coupled to the end of tubular body portion 500. Further, it is contemplated that transition member portions 515, 520, and 525 are hollow tubes, made of a material which swells upon exposure to body fluid. Finally, it is to be understood that a varying number of transition steps may make up the stepped-transition portion. Figure 15 illustrates three portions of varying cross-sectional area for illustrative purposes, but more or less portions may also be employed. In the preceding detailed description, the invention has been described particularly with reference to vascular catheters. It is to be appreciated, however, that the invention is compatible with other types of catheters that are introduced into the body. Thus, the catheter of the invention and the method of placement of the catheter are intended to be applicable to replace any of the various types of catheter uses, including, but not limited to, vascular, neurological, and urinary drainage catheter uses. In the preceding detailed description, the invention is described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the scope of the invention as set forth in the claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

Claims: A catheter (100), for use in a catheter assembly including a catheter introducer (160) adapted to insert a portion of said catheter (100) into the vascular system of a patient's body, the catheter (100) having a proximal end and a distal end and comprising: a substantially tubular body (100), a portion of which is adapted to be placed into a portion of the vascular system of a patient's body, said tubular body (110) having: an outside diameter; and a lumen of generally uniform inside diameter extending axially through said tubular body (110); the catheter (100) further comprising: a transition member (130) coupled to the proximal end of said tubular body (110), said transition member ( 130) having: a lumen extending axially through said transition member (130) and being coaxial with the lumen in said tubular body (110); and an outside diameter, characterised in that : prior to insertion into the vascular system, the transition member (130) is adapted to have an outside diameter which is less than the outside diameter of said tubular body (110); and after insertion into the vascular system, said outside diameter of the transition member (130) is substantially equal to the outside diameter of said tubular body (110). The catheter of claim 1, wherein said transition member (130) is integrally formed with said tubular body (110). The catheter of claim 1 or claim 2, wherein said lumen of said transition member (130) is of a generally uniform diameter. The catheter of any one of claims 1 to 3, wherein said first configuration is a folded state (270) wherein a portion of said transition member (130) is longitudinally folded inward and said second configuration is an unfolded state (280) wherein said outside diameter of said transition member (130) is substantially equivalent to said outside diameter of said tubular body (110). The catheter of any one of claims 1 to 4, wherein said transition member (130) is comprised of an expandable material adapted to expand said lumen of said transition member (130) to said second configuration. The catheter of claim 5, wherein said transition member (130) is a composite of a hydrogel and an elastomer. The catheter of any one of claims 1 to 6, wherein said transition member (130) further comprises a distal portion (515) and a proximal portion (525), wherein the outside diameter of said distal portion (515) is larger than the outside diameter of said proximal portion (525). A catheter kit comprising: an introducer (160) having an axial opening, said introducer (160) being adapted to insert a portion of a catheter (100) into a patient's body; and a catheter as defined in any one of claims 1 to 7 wherein said tubular body (110) of said catheter (100) has an outside diameter no less than the inside diameter of said opening in said introducer (160), and wherein said transition member (130) has an outside diameter that is less than the inside diameter of the opening of said introducer (160). The kit of claim 8, wherein said introducer (160) is comprised of a sheath (150) and handles (140) of a durable material wherein said sheath (150) includes a pair of opposed wall portions which are thinner than the remainder of the sheath (150) and wherein said opposed wall portions substantially extend along said length of said sheath (150), and wherein said sheath (150) is adapted to be divided along said wall portions.

Inventors: BALBIERZ DANIEL J, BALBIERZ, DANIEL J.
Applicants: JOHNSON & JOHNSON MEDICAL, JOHNSON & JOHNSON MEDICAL, INC.
Application year: 1997
Main classification: A61M25
IPC codes: A61M25