Abstract:
A catheter including one or more bidirectional valves is provided. The catheter includes a tubular body having proximal and distal ends, and inner and outer surfaces, and at least one valve formed near the distal end of the tubular body. The valve includes a deformation portion that defines a slit that is openable and closable. The openable/closable slit communicates from the inner surface to the outer surface of the tubular body, wherein the distance between the inner surface and the outer surface of the tubular body progressively becomes thinner approaching the openable/closable slit within the deformation portion.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation application of U.S. patent application Ser. No. 12/463,019, filed May 8, 2009, the entire contents of which are incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a catheter with one or more valves capable of passing a liquid from the interior to the exterior of the catheter or passing a liquid from the exterior to the interior of the catheter via the one or more valves. 
       BACKGROUND 
       [0003]    Catheters have been placed in the body of a patient and used to supply anticancer agents, nutritional formulations, or other such items into a patient&#39;s vein either temporarily or on a long-term basis. To infuse a stabilized drug solution with the use of a catheter in this fashion, it is important that infection and complications be prevented, that the catheter not break or move, and that the catheter also does not become occluded. However, when a catheter with an open tip is used, blood sometimes enters the catheter, coagulates, and the catheter becomes occluded. To prevent occlusion of catheters from such blood coagulation, the interior space of the catheter is generally filled with physiological saline including added heparin; however, this practice is problematic in that it complicates procedures when a catheter is placed in the body of a patient and represents a burden on health care providers and patients. 
         [0004]    Consequently, a catheter including a valve able to prevent occlusion of the catheter due to coagulation of blood has been developed (e.g., see Japanese Unexamined Patent Application Publication S60-58167) by eliminating the tip opening and providing a valve which is normally closed and opens only at times such as when a drug solution is infused between the inside and the outside of the catheter or when blood is collected. Such a catheter with valve (bidirectional valve) is made from an elastic, plastic material, the tip is closed, and at the tip there is formed a linear slit. As a result, when a predetermined pressure differential develops between the inside and outside of such a catheter with valve, the slit opens, and a drug solution can be infused into a vein, or blood within a vein can be released into the catheter and collected. When a predetermined pressure differential between the inside and outside of a catheter with the valve has not developed, the slit is closed, and there is consequently no coagulation of blood within the slit. 
         [0005]    Nonetheless, when a drug solution flows from the inside to the outside of a conventional catheter with valve described above, the slit closes with comparative ease, but a problem exists in that when blood flows from outside toward the inside of the catheter with the valve, the opposing surfaces which form the slit are subject to contact pressure, and it is difficult for the slit to open. 
         [0006]    Therefore, it would be beneficial to have a catheter with a valve capable of providing a smooth the flow of a liquid both when a liquid flows from the inside toward the outside of the catheter, and when a liquid flows from the outside toward the inside of the catheter. 
       SUMMARY 
       [0007]    Accordingly, a catheter with one or more bidirectional valves is provided. The catheter includes a tubular body endowed with elasticity and plasticity and the tip of which is closed, and in which a valve passing from the inside surface to the outside surface of the tubular body and provided with a slit able to open and close is formed at the tip of the tubular body. The outer circumferential portion of the slit in the valve includes a bidirectional deformation part which, when a liquid passes via the valve from the interior to the exterior of the tubular body, or when a liquid passes via the valve from the exterior to the interior of the tubular body, is easily deformed by the pressure of a liquid toward either the outside or the inside of the tubular body and opens the slit. 
         [0008]    The outer circumferential portion of the slit includes a bidirectional deformation part which is easily deformed by the pressure of a liquid toward either the outside or the inside of the tubular body and opens the slit. As a result, the slit is made to open easily not only when a liquid flows from the inside toward the outside, but also when a liquid flows from the outside toward the inside of the catheter with valve, and the flow of a liquid in both inward and outward directions can be made smooth. Additionally, when the pressure differential between the inside and the outside of the catheter with valve is small, the slit is maintained in a closed status by the elasticity of the bidirectional deformation part. 
         [0009]    The slit may be formed so as to extend along the axial direction of the catheter with valve, but the slit may also be extended in a direction oblique to the axial direction of the catheter with valve, or extended so as to be perpendicular thereto. The tubular body may be formed in a circular tube shape, and the bidirectional deformation part may be provided by creating a shape differing from other portions formed in the circular tube shape of the catheter with valve or by making the deformation part more flexible than other parts of the catheter. The liquid pertaining to the present disclosure is, for example, an anticancer agent, nutritional agent, or other such drug solution; blood or the like; or a liquid in infused into a vein or taken from a vein of a patient, and hereinafter, a liquid flowing from the inside toward the outside of the catheter with valve is described as a drug solution, and a liquid flowing from the outside toward the inside of the catheter with valve is described as blood. 
         [0010]    In an alternative embodiment, bidirectional deformation part and the outer circumferential portion of the slit are provided by being made to project to the inside of the tubular body. As a result, when blood flows from the outside to the inside of the catheter with valve due to blood collection or checking for regurgitation, the blood places pressure on the bidirectional deformation part from a recessed surface side, and the slit opens easily. As a result, the flow of blood from the outside toward the inside of the catheter with valve is made smooth. When a drug solution flows from the inside toward the outside of the catheter with valve to supply said solution to the vein of a patient, the drug solution places pressure on the bidirectional deformation part from a projecting surface side, but in such case, infusion of the drug solution is performed by use of an injection syringe or supply device. 
         [0011]    In another embodiment, the bidirectional deformation part is provided by making the outer circumferential portion of the slit thin-walled. As a result, the bidirectional deformation part is easily deformed for the fact of being made thin-walled, and when a drug solution flows from the inside toward the outside, or when blood flows from the outside toward the inside of the catheter with valve, in either case, the slit opens easily, and the flow of drug solution or blood toward its respective direction of orientation can be made smooth. In this instance, the thin-walled bidirectional deformation part may be provided by forming oblique surfaces such that the sides of the slit gradually become thin-walled; by forming a groove-shaped, thin-walled portion at a part maintaining a predetermined interval from the slit; or by making the entire part thin-walled. 
         [0012]    When a thin-walled bidirectional deformation part is provided by forming oblique surfaces, opposing surfaces trapping and confronting the slit in the catheter with valve are provided with a required contact width for closing the slit when the pressure differential between the inside and outside of the catheter with valve is below a predetermined level. The oblique surfaces and groove-shaped, thin-walled part may also be provided at the inner circumference or outer circumference of the bidirectional deformation part, or at both the inner circumference and outer circumference. 
         [0013]    In yet another embodiment, the bidirectional deformation part is provided by forming oblique surfaces on the outer circumference or inner circumference of parts opposed across the slit in the tubular shape, such that the slit side gradually becomes thin-walled. As a result of this configuration, when a drug solution flows from the inside toward the outside, or when blood flows from the outside toward the inside of the catheter with valve, in either case, the slit opens easily, and the flow of drug solution or blood toward its respective direction of orientation can be made smooth. In this instance, when an oblique surface is formed at the outer circumference, and blood thereby flows from the outside toward the inside of the catheter with valve, the slit opens more easily, and when an oblique surface is formed at the inner circumference, and a drug solution thereby flows from the inside toward the outside of the catheter with valve, the slit opens more easily. In these instances too, opposing surfaces trapping and confronting the slit in the catheter with valve are provided with a required contact width for closing the slit when the pressure differential between the inside and outside of the catheter with valve is below a predetermined level. 
         [0014]    In still another embodiment, a plurality of valves provided with a slit and a bidirectional deformation part is formed. As a result, the provision of a plurality of valves allows more reliable inflow of drug solution or outflow of blood through the valve. For example, even if one valve is clogged, infusion of drug solution or outflow of blood can be accomplished through other valves. The plurality of valves in this instance may include an identical item or different items. 
         [0015]    In still yet another embodiment, the plurality of bidirectional deformation parts provided with a plurality of valves includes a bidirectional deformation part provided by forming an oblique surface such that a predetermined slit side at the outer circumference of confronting portions across a predetermined slit among a plurality of slits forms an oblique surface that gradually becomes thin-walled, and a bidirectional deformation part provided by forming an oblique surface such that another slit side at the inner circumference of confronting portions across another slit among the plurality of slits forms an oblique surface that gradually becomes thin-walled. 
         [0016]    As a result, when blood flows from the outside toward the inside of the catheter, a bidirectional deformation part provided by forming an oblique surface at the outer circumference is easily deformed at the inner circumference, and when a drug solution flows from the inside toward the outside of the catheter with valve, a bidirectional deformation part provided by forming an oblique surface at the inner circumference is easily deformed at the outer circumference. When a drug solution flows from the inside toward the outside of the catheter, and when blood flows from the outside toward the inside of the catheter with valve, in both cases, the flow of drug solution or blood can be made smooth. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a planar view illustrating a catheter according to an embodiment of the present disclosure; 
           [0018]      FIG. 2  is a cross-sectional view of  2 - 2  in  FIG. 1 ; 
           [0019]      FIG. 3  is a descriptive view illustrating a catheter placed in the body of a patient; 
           [0020]      FIG. 4  is a cross-sectional view illustrating the tip-side portion of a catheter according to an alternative embodiment of the present disclosure; and 
           [0021]      FIG. 5  is a cross-sectional view illustrating the tip-side portion of a catheter according to another embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Catheters according to embodiments of the present disclosure are described in detail hereafter with the use of drawings.  FIGS. 1 and 2  illustrate a first embodiment of a catheter with valve shown generally as catheter  30 . Catheter  30  is used to supply an anticancer agent, nutritional agent, or other such drug solution into a vein (e.g., B 1 -B 3 ) of a patient A (see  FIG. 3 ). A port  17  is connected to a base terminal  11  before catheter  30  is placed in the vein of the patient A. Catheter  30  includes a long, thin tubular body made from a flexible polyurethane resin and endowed with elasticity and plasticity. A dome-shaped wall portion  12  is formed at the tip of the catheter  30 , and the tip of catheter  30  is closed by this wall portion  12 . Wall portion  12  is made from a polyurethane or silicone softer than the body of catheter  30  and is attached to the body of catheter  30  by adhesion or deposition. 
         [0023]    A valve  33  with a long, thin elliptical shape in planar view (attitude in  FIG. 1 ) along the axial direction (lengthwise direction) of the catheter  30  is formed at an area of the catheter  30  more toward the base terminal  11  than the wall portion  12  on the circumferential surface of the catheter  30 . Valve  33  includes a linear slit  34  extending along the axial direction of catheter  30 , and a bidirectional deformation part  35  formed around slit  34 . Bidirectional deformation part  35  is provided by forming oblique surfaces at the outside of parts opposed across slit  34  in catheter  30 , such that sides defining slit  34  gradually become thin-walled. Bidirectional deformation part  35  forms a recess with a nearly triangular cross-sectional shape provided with two oblique surfaces projecting to the outside of the catheter  30 . 
         [0024]    Slit  34  is opened by deformation of the bidirectional deformation part  35  when the force applied perpendicular to bidirectional deformation part  35  reaches a predetermined value or higher, for example, 50-60 cmH 2 O. If the force applied to bidirectional deformation part  35  is below a predetermined value, the elasticity of bidirectional deformation part  35  provides close contact of the confronting surfaces that form slit  34 , and slit  34  is thereby closed. Bidirectional deformation part  35  can be formed in various ways; for example, once a tubular catheter with a closed end portion is formed, a heat gun or the like can be used on the tip portion thereof to apply an appropriately heated gas, thereby forming the oblique surfaces that include bidirectional deformation part  35 . 
         [0025]    Otherwise, an appropriately heated metal rod can be pressed against the tip-side portion of a tubular catheter with a closed tip portion to form the oblique surfaces that define bidirectional deformation part  35 , or a tubular catheter with a closed tip portion can be covered with shrink tubing, and the oblique surfaces that define bidirectional deformation part  35  can be formed by shrinking a portion of such tubing. Bidirectional deformation part  35  may also be formed at the same time that a tubular catheter with a closed tip portion is formed. Slit  34  may be formed by cutting along the lengthwise direction in the center of bidirectional deformation part  35 . 
         [0026]    With reference now to  FIG. 3 , when catheter  30  is used to supply a drug solution to the vein of a patient A, first, the port  17  is connected to the base terminal  11  of catheter  30 . Port  17  is formed by a septum  19  attached to the surface of a circular, plate-shaped unit  18 , forming an open space (not illustrated) in the interior. Septum  19  includes a material able to be pierced by a needle and endowed with the property that when the needle is withdrawn, the hole created by the needle is blocked. Consequently, when septum  19  in port  17  is pierced by the needle of a syringe filled with a drug solution, and the drug solution flows from the syringe into port  17 , the drug solution passes from the space in port  17  into the interior of catheter  30  and flows outward from slit  34 . 
         [0027]    As shown in  FIG. 3 , catheter  30 , to which port  17  is connected, may be inserted into a vein from the chest region C of patient A or inserted into a vein from an arm D of patient A. When catheter  30 , with port  17  connected, is inserted from the chest region C into a vein, a region near a vein in chest region C, for example subclavian vein B 1 , is incised, catheter  30  is inserted from subclavian vein B 1  located in the vicinity thereof, and the tip-side portion thereof reaches superior vena cava B 2 . Port  17  is then embedded beneath the chest skin. 
         [0028]    When catheter  30  with port  17  attached is inserted into a vein from an arm D, the upper portion of arm D is incised, catheter  30  is inserted from brachial vein B 3  located in the vicinity thereof, and the tip-side portion of catheter  30  reaches superior vena cava B 2  from subclavian vein B 1 . Port  17  is then embedded beneath the chest skin. In either case, the interior of catheter  30  and port  17  are filled with physiological saline. The interior pressure and exterior pressure on catheter  30  are therefore nearly equal, and the closed status of slit  34  is maintained. 
         [0029]    When a drug solution is supplied into the vein of patient A through catheter  30  with port  17  connected, the needle of a syringe filled with a drug solution is first inserted from the skin surface, septum  19  is pierced, and the tip of the needle is positioned within port  17 . The drug solution is then infused from the syringe into port  17 . The drug solution thus passes from the interior of port  17  into catheter  30  and enters superior vena cava B 2  from slit  34 . In this instance, the pressure applied to the drug solution by the syringe is greater than the pressure of blood within superior vena cava B 2 , bidirectional deformation part  35  is thereby easily deformed toward the outside of the catheter  30 , and slit  34  is opened. 
         [0030]    When blood is collected or a check is made for regurgitation, the needle of a syringe from which internal air has been expelled is inserted from the skin surface, and septum  19  is pierced. Then with the tip of the syringe located in port  17 , the plunger of the syringe is withdrawn. Blood within the vein thus passes from the superior vena cava B 2  through slit  34 , and enters the interior of the catheter  30 . In this instance, the suction force of the syringe easily deforms bidirectional deformation part  35  toward the interior of catheter  30 , and slit  34  is opened. In this manner, slit  34  is easily opened both when a drug solution is supplied from the catheter  30  into a vein and when blood within a vein is withdrawn to the inside of the catheter  30 , and the flow of the drug solution or blood is made smooth. When a drug solution is not being infused or blood is not being withdrawn by a syringe, the return force produced by the elasticity of bidirectional deformation part  35  also maintains slit  34  in closed status. Slit  34  opens easily not only when a drug solution flows from the inside toward the outside of the catheter, but also when blood flows from the outside toward the inside of the catheter  30 , and the flow of a drug solution or blood can be made smooth. 
         [0031]    Bidirectional deformation part  35  is deformed by additional pressure or reduced pressure derived from operation of a syringe, and slit  34  opens easily, but when blood flows from the outside toward the inside of catheter  30 , the blood puts pressure on bidirectional deformation part  35  from the recess side, and slit  34  therefore opens even more easily. If the pressure differential between the inside and outside of catheter  30  is small, slit  34  is maintained in closed status by the elasticity of bidirectional deformation part  35 . At such time, the opposing surfaces that form slit  34  in catheter  30  are in a state of contact with each other, and consequently there is no coagulation of blood within slit  34 . 
         [0032]    With reference now to  FIG. 4 , the cross-section of the tip portion of a catheter  30   a  according to an alternative embodiment of the present disclosure is illustrated. Catheter  30   a  includes a bidirectional deformation part  35   a  of a valve  33   a  provided by forming oblique surfaces at the inner circumference of portions opposed across a slit  34   a  in catheter  30   a , such that the sides defining slit  34   a  gradually become thin-walled. The structure of other portions of catheter  30   a  is identical to that of the catheter  30  described above. 
         [0033]    When the catheter  30   a  is used to supply a drug solution into a vein of a patient A, the same procedure as described above can be performed, in which a catheter  30  was used to supply a drug solution into a vein of a patient A. As a result, when a drug solution flows from the inside toward the outside of the catheter, and when blood flows from the outside toward the inside of the catheter  30   a , in either case, the slit  34   a  opens easily, and the flow of drug solution or blood toward its respective direction of orientation can be made smooth. The formation of oblique surfaces at the inner circumference adjacent slit  34   a  as in the catheter  30   a  allows the slit  34   a  to open more easily when a drug solution flows from the inside toward the outside of the catheter  30   a . Other operational effects of the catheter  30   a  are similar to the operational effects of the catheter  30  described above. 
         [0034]    Turning now to  FIG. 5 , a cross-section of the tip-side portion of a catheter  40  according to another embodiment of the present disclosure is illustrated. Catheter  40  includes a plurality of valves  43   a ,  43   b  formed at regular intervals along the circumference. As shown, catheter  40  includes two (2) valves  43   a  and two (2) valves  43   b  disposed alternately about the circumference of catheter  40 . Bidirectional deformation part  45   a  of valves  43   a  is provided by forming oblique surfaces at the outer circumference of portions opposed across the slit  44   a  in catheter  40  such that the sides defining slit  44   a  gradually become thin-walled. Bidirectional deformation part  45   b  of valve  43   b  is provided by forming oblique surfaces at the inner circumference of portions opposed across the slit  44   b  in catheter  40  such that the sides defining slit  44   b  gradually become thin-walled. 
         [0035]    The structure of other portions of the catheter  40  is identical to that of the catheter  30  and others described above. When the catheter  40  is used to supply a drug solution into a vein of a patient A, the same procedure as described above may be performed, in which catheter  30  or others were used to supply a drug solution into a vein of a patient A. Accordingly, because a plurality of valves  43   a ,  43   b  is provided, infusion of a drug solution or collection of blood through the valves  43   a ,  43   b  can be performed more reliably. Additionally, due to this catheter with valve  40 , if for example, one among the plurality of valves  43   a ,  43   b  becomes clogged, infusion of a drug solution or collection of blood through other of the valves  43   a ,  43   b  can still be performed. 
         [0036]    When blood flows from the outside toward the inside of catheter  40 , in either case, valves  43   a  open easily, and when a drug solution flows from the inside toward the outside of catheter  40 , valves  43   b  open easily. As a result, when a drug solution flows from the inside toward the outside, and when blood flows from the outside toward the inside of catheter  40 , in either case, the flow of drug solution or blood may be made smooth. Other operational effects of catheter  40  are similar to the operational effects of catheter  30  and others described above. 
         [0037]    The catheters of the present disclosure are not limited to the individual embodiments described above and may be implemented with suitable modifications. For example, bidirectional deformation parts  35 ,  35   a  of catheters  30 ,  30   a , respectively, are provided by forming oblique surfaces at the outer circumference or inner circumference of portions opposed across slit  34 ,  34   a , such that the sides defining slits  34 ,  34   a  gradually become thin-walled; however, a bidirectional deformation part may also be provided by forming oblique surfaces at both the outer circumference and the inner circumference. 
         [0038]    A bidirectional deformation part can also be provided by forming a groove-shaped, thin-walled portion at a portion maintaining a predetermined interval from slit  34  or others, and a bidirectional deformation part can also be provided by making the entire circumference of slit  34  or others thin-walled. The number of bidirectional deformation parts when a plurality is provided is also not limited to 4; 3 or fewer or 5 or more are also acceptable, and individual bidirectional deformation parts with shapes differing suitably can also be used in combination. A bidirectional deformation part may also be provided by making the part more flexible than other portions of a catheter. The outer circumferential portion of a slit may also be made into a bidirectional deformation part by making the inner space eccentric, such that the portion of a catheter with valve where a slit is provided gradually becomes thinner-walled than other portions. 
         [0039]    In addition to a polyurethane resin, the material used to comprise catheter  30  or others described above may be a silicone, nylon, or a polyvinyl chloride. Additionally, in the embodiments described above, a port  17  is connected to a base terminal  11  of a catheter  30  or others, but the base terminal  11  of catheter  30  or others may also be connected to a transfusion line. As discussed above, catheter  30  or others was placed in a vein, but a predetermined method may also be used to place catheter  30  or others in an artery. 
         [0040]    Although specific features of the catheter with valve are shown in some of the drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the aspects of the present disclosure. Other embodiments will occur to those skilled in the art and are within the following claims.