Patent Publication Number: US-2011054403-A1

Title: Indwelling needle assembly and method of using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2009-196830 filed on Aug. 27, 2009, of which the contents are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an indwelling needle assembly to be used to puncture a blood vessel and be left indwelling there, in the case of an infusion, for example. 
     2. Description of the Related Art 
     At the time of carrying out an infusion on a patient or in other similar situations, an indwelling needle to be connected with an infusion line is made to puncture a patient&#39;s blood vessel and is left indwelling for performing the infusion. 
     Such an indwelling needle assembly, normally, includes a hollow outer needle, an outer needle hub secured to a base end (proximal end) of the outer needle, an inner needle which is inserted into the outer needle and which has a sharp needle point at a tip (distal end) thereof, an inner needle hub secured to a base end (proximal end) of the inner needle, and a protector which is detachably coupled to the outer needle hub. The outer needle hub is formed with a main pipe having a flow path communicating with the lumen of the outer needle, and a side pipe having a branch flow path branched from the flow path in the main pipe, wherein an infusion line is to be connected to the side pipe (see, for example, U.S. Pat. No.  6 , 749 , 588 ). 
     At the time of puncturing a patient&#39;s blood vessel with the indwelling needle, a puncturing operation is conducted in an assembled condition wherein the inner needle is inserted into the outer needle and the needle point of the inner needle protrudes from the tip (distal end) of the outer needle. 
     When the needle point of the inner needle has reached the inside of the blood vessel, blood flows into the inner needle through its distal portion, the blood, in its course of flowing, flows through a hole formed in a side portion of the inner needle into a flow path between the outer needle and the inner needle, then flows through the flow path into the inside of the transparent outer needle hub, that is, into the flow path in the main pipe and, further, flows from the main pipe into the branch flow path in the side pipe (flashback). This permits a clinician (user) to confirm (visually recognize) that the inner needle has captured (securely punctured) the blood vessel. 
     After flashback is confirmed, the outer needle is advanced using the inner needle as a guide, and the outer needle is made to puncture the blood vessel. 
     Next, while fixing the outer needle or the outer needle hub by holding it by one hand, the inner needle hub is held by the other hand and moved in the proximal direction, to draw the inner needle out of the outer needle. Then, an infusion agent is administered through the connected infusion line, the side pipe of the outer needle hub, the main pipe of the outer needle hub, and the outer needle. 
     Meanwhile, at the time of putting the outer needle of the indwelling needle assembly indwelling in a patient, the clinician (user) wears gloves, holds the indwelling needle assembly with fingers of the gloved hand, and performs the puncturing operation. In the case of the puncturing operation, the clinician may hold the indwelling needle assembly by a method as shown in  FIG. 3 , for example. 
     This holding method is herein referred to as “wing port holding.” In this holding method, the thumb is put in contact with the proximal end of the inner needle hub, whereas one of the remaining fingers, for example, the middle finger is put in contact with the distal side of the indwelling needle assembly, specifically, a wing of the outer needle hub, whereby the indwelling needle assembly is held so as to be pinched in the longitudinal direction thereof. 
     In an indwelling needle assembly according to the related art, however, fingers of a gloved hand are liable to slip relative to the indwelling needle assembly at the time of a puncturing operation. Particularly, the thumb is liable to slip off a base portion (proximal portion) of the inner needle hub, which makes the puncturing operation difficult to achieve. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an indwelling needle assembly which is less liable to slipping and, hence, permits a puncturing operation therewith to be carried out easily. 
     The above object can be attained by the present invention as represented by the following. 
     An embodiment of the present invention provides an indwelling needle assembly, including: 
     an inner needle having a sharp needle point at a distal end thereof; 
     an inner needle hub fixed to a proximal portion of the inner needle; 
     a hollow outer needle into which the inner needle is inserted; and 
     an outer needle hub fixed to a proximal portion of the outer needle, the indwelling needle assembly being designed to be used with a thumb in contact with a proximal portion of the inner needle hub, 
     wherein the inner needle hub is provided with a finger hold at the proximal portion thereof, and at least a part of the finger hold is formed from a material less liable to slip on a medical glove. 
     In the indwelling needle assembly according to the embodiment of the present invention, 
     the inner needle hub has an inner needle hub body part formed from a resin material, and the finger hold has a projected part which is formed from the material less liable to slip on the medical glove and which is projected to a proximal side relative to a proximal end face of the inner needle hub body part. 
     In the indwelling needle assembly according to the embodiment of the present invention, the projected part is disposed at a central portion of the proximal end face. 
     In the indwelling needle assembly according to the embodiment of the present invention, the projected part is provided with a recess in a central portion thereof. 
     In the indwelling needle assembly according to the embodiment of the present invention, the projected part extends radially from a center of the proximal end face. 
     In the indwelling needle assembly according to the embodiment of the present invention, a value of “a/b” is in a range from 0.01 to 0.8, where “a” is an area of projection of the projected part onto a plane perpendicular to an axis of the inner needle, and “b” is an area of projection, onto the plane, of the projected part and a part of the proximal end face where the projected part is not provided. 
     In the indwelling needle assembly according to the embodiment of the present invention, the proximal end face of the projected part is formed with a plurality of minute recesses and projections. 
     A method of using an indwelling needle assembly according to an embodiment of the present invention includes the steps of: 
     preparing the indwelling needle assembly including an inner needle having a sharp needle point at a distal end thereof, an inner needle hub fixed to a proximal portion of the inner needle, a hollow outer needle into which the inner needle is inserted, and an outer needle hub fixed to a proximal portion of the outer needle, the indwelling needle assembly being provided with a finger hold at the proximal portion thereof, at least a part of the finger hold being formed from a material less liable to slip on a medical glove; 
     putting a thumb of a hand in contact with the finger hold of the indwelling needle assembly in an assembled condition wherein the inner needle is inserted into the outer needle and the needle point of the inner needle protrudes from a distal end of the outer needle, putting one of the remaining fingers of the hand in contact with a distal side of the indwelling needle assembly, and thereby holding the indwelling needle assembly so as to pinch the indwelling needle assembly in a longitudinal direction thereof; and 
     puncturing a living body with the inner needle and the outer needle. 
     The method of using the indwelling needle assembly according to the embodiment of the present invention, preferably, includes a step of wearing a glove. 
     According to the embodiment of the present invention, at least a part of the finger hold is formed from a material less liable to slip on a medical glove. Therefore, the thumb of the hand holding the indwelling needle assembly can be prevented from slipping off the finger hold (the proximal portion of the inner needle hub), which permits the puncturing operation to be carried out easily and safely. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing an embodiment of the indwelling needle assembly according to the present invention; 
         FIG. 2A  is a side view of the indwelling needle assembly shown in  FIG. 1 ; 
         FIG. 2B  is a rear view of the indwelling needle assembly shown in  FIG. 1 ; 
         FIG. 3  is a side view showing a condition where the indwelling needle assembly shown in  FIG. 1  is held; 
         FIG. 4  is an exploded perspective view of the indwelling needle assembly shown in  FIG. 1 ; 
         FIG. 5  is a sectional view showing an outer needle hub, an inner needle, an inner needle hub, a protector, etc. of the indwelling needle assembly shown in  FIG. 1 ; 
         FIG. 6  is a sectional view taken along line A-A of  FIG. 5 ; 
         FIG. 7  is a sectional view showing the outer needle hub, the inner needle, the inner needle hub, the protector, etc. of the indwelling needle assembly shown in  FIG. 1 ; 
         FIG. 8  is a perspective view showing a coupling member of the protector in the indwelling needle assembly shown in  FIG. 1 ; 
         FIG. 9  is a bottom view showing schematically the outer needle hub and the coupling member of the protector in the indwelling needle assembly shown in  FIG. 1 ; 
         FIG. 10  is a bottom view showing schematically the outer needle hub and the coupling member of the protector in the indwelling needle assembly shown in  FIG. 1 ; 
         FIGS. 11A to 11F  illustrate other configuration examples in the indwelling needle assembly in this embodiment; and 
         FIGS. 12G to 12K  illustrate other configuration examples in the indwelling needle assembly in this embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now, an indwelling needle assembly according to the present invention will be described in detail below, based on preferred embodiments shown in the accompanying drawings. 
       FIG. 1  is a perspective view showing an embodiment of the indwelling needle assembly according to the present invention;  FIGS. 2A and 2B  illustrate the indwelling needle assembly shown in  FIG. 1 , wherein  FIG. 2A  is a side view and  FIG. 2B  is a rear view;  FIG. 3  is a side view showing a condition where the indwelling needle assembly shown in  FIG. 1  is held;  FIG. 4  is an exploded perspective view of the indwelling needle assembly shown in  FIG. 1 ;  FIG. 5  is a sectional view showing an outer needle hub, an inner needle, an inner needle hub, a protector, etc. of the indwelling needle assembly shown in  FIG. 1 ;  FIG. 6  is a sectional view taken along line A-A of  FIG. 5 ;  FIG. 7  is a sectional view showing the outer needle hub, the inner needle, the inner needle hub, the protector, etc. of the indwelling needle assembly shown in  FIG. 1 ;  FIG. 8  is a perspective view showing a coupling member of the protector in the indwelling needle assembly shown in  FIG. 1 ; and  FIGS. 9 and 10  each are bottom views showing schematically the outer needle hub and the coupling member of the protector in the indwelling needle assembly shown in  FIG. 1 . 
     Incidentally, in the following description, the right side in  FIGS. 2A ,  3 ,  9  and  10  will be taken as “proximal (trailing end)” and the left side as “distal (leading end).” In addition, the left side in  FIGS. 4 ,  5  and  7  will be taken as “proximal (trailing end)” and the right side as “distal (leading end).” Besides, in  FIGS. 9 and 10 , of a coupling member of a protector, only a first part and a projection piece are drawn. 
     An indwelling needle assembly  1  shown in the drawings has a hollow outer needle  2 , an outer needle hub  3  fixed to a proximal portion of the outer needle  2 , an inner needle  4  to be inserted into the outer needle  2 , an inner needle hub  5  which is fixed to a proximal portion of the inner needle  4  and which is provided with a finger hold  54  at its proximal portion to be contacted by the thumb of a hand holding the indwelling needle assembly  1 , and a tube  7  which is connected to a side portion of the outer needle hub  3  so that its lumen  71  communicates with a lumen  21  of the outer needle  2 . 
     The outer needle  2 , preferably, has a certain degree of flexibility. The material constituting the outer needle  2  is preferably a resin material, particularly, a soft or flexible resin material. Specific examples of the material include fluororesins such as PTFE, ETFE, PFA, etc., olefin resins such as polyethylene, polypropylene, etc. and mixtures thereof, polyurethane, polyesters, polyamides, polyether nylon resins, mixtures of an olefin resin with an ethylene-vinyl acetate copolymer, etc. 
     A portion or the entirety of the outer needle  2  as above may enable the inside thereof to be visible. In addition, the outer needle  2  may be provided with radiopacity by blending a radiopaque material such as barium sulfate, barium carbonate, bismuth carbonate, tungstic acid, etc. into the material constituting the outer needle  2 . 
     The outer needle hub  3  is fixed, in a liquid-tight fashion, to a proximal portion of the outer needle  2  by, for example, caulking, fusing (heat fusing, microwave fusing, etc.), adhesion with an adhesive, or the like. 
     The outer needle hub  3  has a main pipe  36  which is substantially tubular, and a side pipe  37  which is substantially tubular and which has a branch flow path  32  branched from a flow path  31  in the main pipe  36 . 
     As above-mentioned, a proximal portion of the outer needle  2  is fixed to the distal side of the main pipe  36 , and the flow path  31  communicates with the lumen  21  of the outer needle  2  on the distal side thereof. The flow path  31  (main pipe  36 ) is so disposed that its axis coincides substantially with the center axis of the outer needle  2 . 
     On the other hand, the branch flow path  32  (side pipe  37 ) is so disposed that its axis is inclined at a predetermined angle in relation to the center axis of the outer needle  2 , that is, the axis of the flow path  31 . In this case, the branch flow path  32  is so inclined that the proximal side of the branch flow path  32  is located on the right side in  FIGS. 1 to 3 . Incidentally, the axis of the branch flow path  32  may be perpendicular to the axis of the flow path  31 . 
     Besides, a distal portion of the tube  7  is connected to the side pipe  37  of the outer needle hub  3 . This ensures that a liquid such as a medicinal liquid can be supplied into the outer needle  2  through the tube  7 . 
     In addition, the outer needle hub  3  is formed with a rib  33  at a proximal portion thereof. The rib  33  will be described in detail later. 
     Besides, on lateral sides of the outer needle hub  3 , a pair of wings  12   a  and  12   b  are formed integrally with the outer needle hub  3 . At the time of puncturing a blood vessel or the like with the outer needle  2  and the inner needle  4 , puncturing is conducted by holding the indwelling needle assembly  1 , and, when the distal end of the outer needle  2  has entered the blood vessel, the outer needle hub  3  is advanced while pushing a finger hold  916  (described later) by an index finger, whereby only the outer needle  2  can be advanced into the inside of the blood vessel. At the time of leaving the outer needle  2  indwelling, the wings  12   a  and  12   b  are fixed to a skin by a pressure sensitive adhesive tape or the like. 
     The inner needle  4  having a sharp needle point  41  at the distal end thereof is inserted into the outer needle  2 . The indwelling needle assembly  1  is used in a condition where the inner needle  4  is inserted into the outer needle  2  and the needle point  41  protrudes from a tip opening (distal end)  22  of the outer needle  2 , that is, in the condition shown in  FIGS. 1 to 3 ,  5 ,  6  and  9 . Hereinafter, this condition will be referred to as the “assembled condition.” 
     The length of the inner needle  4  is set to such a value that at least the needle point  41  protrudes from the tip opening  22  of the outer needle  2  in the assembled condition. 
     The inner needle  4  may be a hollow needle, or may be a solid (non-hollow) needle. 
     In the configuration shown in the drawings, the inner needle  4  is a hollow needle, which is formed with a hole (side hole) (not shown) in a side portion of an intermediate part thereof. This ensures that when a blood vessel is punctured with the inner needle  4 , blood flows into the hollow portion of the inner needle  4 , and the blood, in its course of flowing, flows through the hole formed in the side portion of the inner needle  4  into a gap between the inner needle  4  and the outer needle  2 , which permits flashback of the blood to be confirmed earlier. 
     Incidentally, the inner needle  4  may have a configuration including both a hollow portion and a solid portion (for example, a configuration obtained by filling up a part of the lumen of a hollow needle so that the needle is hollow on the distal side and solid on the proximal side). Where the inner needle is wholly composed of a single member, a reduction in the cost of the inner needle  4  can be promised. 
     In addition, the inner needle  4  may be uniform in outside diameter, or may have a plurality of portions which are different in outside diameter. 
     Examples of the material constituting the inner needle  4  include metallic materials such as stainless steel, aluminum, aluminum alloys, titanium, titanium alloys, etc. 
     The inner needle hub  5  is fixed to a proximal portion of the inner needle  4 . Specifically, the inner needle hub  5  has an inner needle hub body part  50 , and the proximal portion of the inner needle  4  is fixed to the inner needle hub body part  50 . Examples of the method for fixing the inner needle  4  to the inner needle hub  5  (the inner needle hub body part  50 ) include such methods as fitting, caulking, fusing, adhesion with an adhesive, etc. and combinations thereof. Incidentally, in the configuration shown in the figure, the inner needle  4  is hollow, and, therefore, the inner needle  4  is sealed so that the blood flowing back upon puncturing of a blood vessel is prevented from flying out from a proximal portion of the inner needle hub  5 . 
     In addition, the inner needle hub body part  50  is provided with a protector insertion part (a connecting member accommodation part)  51  at a distal portion thereof into which a proximal portion of a protector  9  (described later) is inserted and a connecting member  20  (described later) is accommodated in the assembled condition. The protector  9  and the connecting member  20  can be moved relative to the protector insertion part  51 . 
     Besides, the inner needle hub  5  is provided with the finger hold  54  at its proximal portion. Incidentally, the finger hold  54  will be described in detail later. 
     Each of the inner needle hub  5  as above and the outer needle hub  3  as above-described is preferably formed of a transparent (colorless transparent) or colored transparent or semi-transparent resin, so as to ensure visibility of the inside thereof. This ensures that when the outer needle  2  is securely inserted into a blood vessel, the flashback of the blood flowing in through the aforementioned inner needle  4  can be confirmed visually. 
     Materials constituting the outer needle hub  3 , the inner needle hub  5  and the wings  12   a  and  12   b  are not particularly limited. Examples of the respective materials constituting the outer needle hub  3  and the wings  12   a,    12   b  include various resin materials, for example, polyolefins such as polyethylene, polypropylene, an ethylene-vinyl acetate copolymer, etc., polyurethane, polyamides, polyesters, polycarbonate, polybutadiene, polyvinyl chloride, polyacetal, etc. The material constituting the inner needle hub  5  will be described later. 
     The tube  7  is flexible, and its distal portion is connected to the side pipe  37  of the outer needle hub  3 , as mentioned above. The tube  7  is provided with a branching part at its proximal portion where the flow path is branched into two branch flow paths, one of which is fitted with a connector  72  and the other of which is fitted with a connector  73 . Each of the connectors  72  and  73  is connected to, for example, a connector equipped at an end portion of an infusion line for supplying an infusion liquid (medicinal liquid) to be administered, a mouth part of a syringe filled with a medicinal liquid, or the like. 
     Incidentally, the material constituting the tube  7  is not particularly limited. Examples of the material include polyolefins such as polyethylene, polypropylene, an ethylene-vinyl acetate copolymer, etc., polyvinyl chloride, polybutadiene, polyamides, polyurethane, polyesters, etc. 
     In addition, the indwelling needle assembly  1  is provided, in the flow path  31  in the outer needle hub  3 , with a cylindrical (block-formed) seal member (not shown) as sealing means for sealing the flow path  31 . The seal member is disposed (fixed) on the proximal side, relative to the branch flow path  32 , of the flow path  31  in the main pipe  36 . In this embodiment, the seal member is arranged in the vicinity of the branch flow path  32 . 
     The seal member is formed with a hole or slit which permits the inner needle  4  to be inserted thereinto and therethrough and which is closed when the inner needle  4  thus inserted is pulled out. In this embodiment, the seal member is formed substantially in its center with a slit (not shown) which penetrates the seal member in the longitudinal direction of the seal member. 
     The slit is in the shape of a straight line segment. This ensures that the slit in a closed state can easily be put into an open state. Therefore, the inner needle  4  can be smoothly passed through the seal member (slit). Specifically, when the outer needle  2  is advanced using the inner needle  4  as a guide, which will be described later, the frictional resistance between the outer surface of the inner needle  4  and the inner surface of the slit can be reduced. Accordingly, operability at the time of a puncturing operation of the indwelling needle assembly  1  is further enhanced. 
     The seal member has a self-closing property such that the inner needle  4  is inserted into and through the slit in the assembled condition and that, when the inner needle  4  thus inserted is pulled out, the slit is closed by an elastic force (restoring force) possessed by the seal member itself. This ensures that when the inner needle  4  is pulled out, leakage of liquid from the proximal end of the outer needle hub  3  can be prevented from occurring and that the inside of the outer needle hub  3  can be maintained in an aseptic condition. 
     Examples of the material constituting the seal member as above include various elastic materials such as various rubber materials (particularly, vulcanized ones) such as natural rubber, isoprene rubber, butyl rubber, butadiene rubber, styrene-butadiene rubber, urethane rubber, nitrile rubber, acrylic rubber, fluoro-rubber, silicone rubber, etc., various thermoplastic elastomers based on urethane, polyester, polyamide, olefin, styrene or the like, and mixtures of them. 
     In addition, the indwelling needle assembly  1 , preferably, is preliminarily subjected to a friction-reducing treatment for reducing the frictional resistance between the inner surface of the slit and the outer surface of the inner needle  4 . 
     Examples of the friction-reducing treatment include a treatment in which a lubricant is applied to at least one of the inner surface of the slit and the outer surface (outer peripheral surface) of the inner needle  4 , and a treatment in which a layer formed of a low-friction material (low-friction layer) is formed on the inner surface of the slit. 
     Such a friction-reducing treatment ensures that when the outer needle  2  is advanced using the inner needle  4  as a guide, the frictional resistance between the inner needle  4  and the seal member can be reduced assuredly. Consequently, the outer needle  2  can be moved smoothly, and the indwelling needle assembly  1  is made to be excellent in operability at the time of a puncturing operation. 
     In addition, the indwelling needle assembly  1  has the protector  9  which covers at least the needle point  41  of the inner needle  4  when the inner needle  4  is drawn out of the outer needle  2 . The description of the protector  9  will be made in the following. 
     In the assembled condition, the protector  9  is inserted (disposed) into the protector insertion part  51  of the inner needle hub  5 . 
     The protector  9  is detachably coupled to the outer needle hub  3 . As shown in  FIGS. 4 ,  5  and  7 , the protector  9  has a protector body  91  and a coupling member  92  provided inside the protector body  91 . 
     The protector body  91  is provided with a bottomed hole part  911  at its distal portion, into which a proximal portion of the outer needle hub  3  is inserted in the assembled condition. 
     The material constituting the protector body  91  is not particularly limited. For example, materials identical or similar to those mentioned above as material for constituting the outer needle hub  3  and the inner needle hub  5  can be used. 
     Besides, the coupling member  92  is accommodated on the proximal side in the hole part  911  of the protector body  91 . Specifically, the protector body  91  is provided with a wall part  912  which constitutes a bottom wall of the hole part  911 , and a wall part  913  which is disposed on the proximal side of the wall part  912 , and the coupling member  92  is disposed between the wall part  912  and the wall part  913 . 
     As shown in  FIGS. 5 ,  7  and  8 , the coupling member  92  has a plate-like projection piece  924  which is elastic and capable of engagement with the rib  33  of the outer needle hub  3 . In the assembled condition, the protector  9  is detachably coupled to the outer needle hub  3  through the engagement between the projection piece  924  of the coupling member  92  and the rib  33  of the outer needle hub  3 , in the condition where a proximal portion of the outer needle hub  3  is inserted into the hole part  911  of the protector  9 . 
     In this embodiment, the coupling member  92  is substantially V-shaped as a whole, and is a member (plate spring) formed by bending an elastic belt-like plate member into a substantially V-shaped form. Specifically, the coupling member  92  includes a first part  921 , a second part  922  which is connected to the upper side in  FIG. 8  of the first part  921  and which forms the substantially V-shaped form together with the first part  921 , a third part  923  disposed on the lower side in  FIG. 8  of the first part  921 , the projection piece  924  projecting toward the upper side in  FIG. 8  from the proximal end of the third part  923 , and a shutter part  925  arranged on the proximal side at an intermediate portion of the first part  921 . In addition, a part on the lower side in  FIG. 8  of the second part  922  is curved or bent toward the upper side. Besides, an opposed surface  926 , opposed to a sliding surface  331  of the rib  33  (described later), of the projection piece  924  is substantially perpendicular to the center axis O 1  of the inner needle  4 . 
     The coupling member  92  can assume a first state in which its projection piece  924  is in engagement with the rib  33  and a second state in which the projection piece  924  is out of engagement with the rib  33 , through a change in the opening angle between the first part  921  and the second part  922 . 
     To be more specific, in the assembled condition as shown in  FIGS. 5 ,  6  and  9 , the coupling member  92  is accommodated in the state of being folded to have a small opening angle, with its first part  921  in contact with the outer peripheral surface of the inner needle  4 , whereby the coupling member  92  is maintained in the first state. In this state, the protector  9  is coupled with the outer needle hub  3 . Besides, the protector  9  and the outer needle hub  3  can be moved, in the longitudinal direction of the inner needle  4 , relative to the inner needle  4  and the inner needle hub  5 . 
     When, starting from this condition, the inner needle hub  5  is moved in the proximal direction relative to the protector  9  and the needle point  41  of the inner needle  4  reaches the proximal side of the first part  921  of the coupling member  92 , the coupling member  92  opens under its own elastic force as shown in  FIGS. 7 and 10  and is pulled in the proximal direction through the connecting member  20  (described later), resulting in the second state. The direction in which the projection piece  924  is moved by the restoration of the coupling member  92  is substantially perpendicular to the center axis O 1  of the inner needle  4 . In this condition, the protector  9  and the outer needle hub  3  are out of mutual coupling. In addition, the shutter part  925  of the coupling member  92  is located on the distal side of the needle point  41  on the center axis O 1  of the inner needle  4 , whereby the needle point  41  is inhibited from moving in the distal direction beyond the coupling member  92 . Incidentally, when the inner needle hub  5  is further moved in the proximal direction, the protector  9  is pulled and moved in the proximal direction through the connecting member  20  (described later), thereby being disengaged from the outer needle hub  3 . 
     The material constituting the coupling member  92  is not particularly limited. Examples of the material include various resin materials identical or similar to those mentioned above as material for the outer needle hub  3  and the inner needle hub  5 , and various metallic materials such as stainless steel, aluminum, aluminum alloys, titanium, titanium alloys, copper, copper alloys, etc. 
     Incidentally, part of the coupling member  92  may be fixed to the protector body  91  by, for example, caulking, press fitting, fusing, adhesion with an adhesive, or the like. Besides, the coupling member  92  is not limited to the configuration shown in the drawings but may be of other form or structure. 
     In addition, at a distal portion of the protector body  91 , the finger hold  916  is formed in a projecting form. The protector body  91  and the finger hold  916  are formed integrally with each other. Besides, the finger hold  916  is projecting toward the upper side. With the finger hold  916  pushed in the distal direction by a finger, the outer needle  2  can be moved in the distal direction relative to the inner needle  4 . 
     Incidentally, the protector body  91  and the finger hold  916  may be formed as separate members and may be joined to each other. In this case, the material constituting the finger hold  916  is not particularly limited; for example, materials identical or similar to those mentioned above as material for constituting the outer needle hub  3  can be used. In addition, the finger hold  916  may be projectingly formed on other part, for example, the outer needle hub  3 . 
     Besides, as shown in  FIGS. 4 ,  5  and  7 , the indwelling needle assembly  1  has the connecting member  20  which has both a slip-off preventing function for preventing the protector  9  from slipping off the needle point  41  of the inner needle  4  when the needle point  41  has been covered by the protector  9 , and a connecting function for connecting the protector  9  and the inner needle hub  5  to each other. 
     The connecting member  20  is so configured as to interconnect the protector body  91  of the protector  9  and the inner needle hub  5 . This ensures that when the inner needle hub  5  is moved in the proximal direction, the protector  9  is pulled in the proximal direction through the connecting member  20 . 
     In addition, the connecting member  20  is bellows-like in form and, hence, can be contracted and extended. The connecting member  20  has such a length that, when the connecting member  20  is in its maximally extended state (a fully extended state), the needle point  41  of the inner needle  4  is located on the proximal side relative to the shutter part  925  of the coupling member  92  and the needle point  41  is accommodated in the protector body  91  (the needle point  41  would not slip off from the protector body  91 ). 
     Thus, the connecting member  20  connects the protector body  91  and the inner needle hub  5  to each other and has such a length that, when the connecting member  20  is in its maximally extended state, the needle point  41  is accommodated in the protector body  91 . Therefore, the protector  9  is securely prevented from slipping off from the needle point  41  of the inner needle  4 , and, accordingly, the condition where the needle point  41  is covered by the protector  9  can be maintained assuredly. Consequently, an accident is securely prevented, in which the worker or the like sticks the needle point  41  in his or her finger or the like by mistake at the time of discarding the inner needle  4  or in other similar situations, so that high safety is attained. 
     In addition, the connecting member  20  is contracted, or folded, in the assembled condition, and is extended, or unfolded, in the condition where the inner needle  4  has been pulled out of the outer needle  2  and the needle point  41  is covered by the protector  9 . 
     Such a connecting member  20  is contracted in the assembled condition, and is accommodated, in the contracted state, in the protector insertion part  51  of the inner needle hub  5 , on the proximal side relative to the protector  9 . This ensures that at the time of a puncturing operation, the connecting member  20  would not obstruct the operation and, therefore, operability of the indwelling needle assembly  1  is enhanced. In addition, there is also obtained a merit of a reduction in the size of the indwelling needle assembly  1 . 
     Besides, when the connecting member  20  is in the contracted state and when it is in the extended state, the inner needle  4  is penetrating the connecting member  20 . As a result, the inner needle  4  functions as a guide for the connecting member  20  at the times of contraction and extension of the connecting member  20 . Therefore, for example when the indwelling needle assembly  1  is put into the assembled condition (is manufactured), it is possible to securely prevent the connecting member  20  from being contracted in an unwilling state, or from being contracted without being accommodated in the inner needle hub  5 . 
     In addition, the connecting member  20  has a self-restoring property with which it tends to return to its natural state. Therefore, in the state of being contracted more than in its natural state, the connecting member  20  functions as biasing means for biasing in the extending direction by its restoring force; in the state of being extended more than in its natural state, the connecting member  20  functions as biasing means for biasing in the contracting direction by its restoring force. The term “natural state” used herein means the condition where no external force is acting on the connecting member  20 . 
     Incidentally, the connecting member  20  may be so configured as to connect the protector  9  and the inner needle  4  to each other. 
     As shown in  FIGS. 4 ,  5 ,  7 ,  9  and  10 , the outer needle hub  3  of the indwelling needle assembly  1  is provided with the rib  33  at a proximal portion thereof as a projected part capable of engagement with the projection piece  924  of the coupling member  92  of the protector  9  described above. 
     The rib  33  is formed on the outer peripheral surface of a proximal portion of the outer needle hub  3  along the circumferential direction. In the configuration shown in the drawings, the rib  33  is annular in shape. 
     The rib  33  has the sliding surface  331  which is inclined in relation to the center axis (axis) O 1  of the inner needle  4  and on which the projection piece  924  slides. In this configuration, when the coupling member  92  is shifted from the first state shown in  FIGS. 5 ,  6  and  9  to the second state shown in  FIGS. 7 and 10 , the projection piece  924  of the coupling member  92  slides along the sliding surface  331 . Specifically, when the inner needle  4  is pulled out of the outer needle  2 , the coupling member  92  is restored as its first part  921  is separated from the outer peripheral surface of the inner needle  4 , and, when the coupling member  92  is thus restored, the projection piece  924  slides along the sliding surface  331  of the rib  33 , and the coupling member  92  comes into the second state. 
     This ensures that, at the time of pulling the inner needle  4  out of the outer needle  2  and releasing the protector  9  from the outer needle hub  3 , friction can be reduced. Consequently, the operating of pulling the inner needle  4  out of the outer needle  2  and disengaging the protector  9  from the outer needle hub  3  can be carried out smoothly and assuredly. 
     In addition, since the sliding surface  331  is inclined, the area of a contact portion between the projection piece  924  and the sliding surface  331  of the rib  33  is small, which ensures that the sliding resistance between the projection piece  924  and the sliding surface  331  of the rib  33  is small. Consequently, the projection piece  924  can be slid along the sliding surface  331  of the rib  33  more smoothly. 
     The inclination angle θ of the sliding surface  331  of the rib  33  against the center axis O 1  of the inner needle  4  (the angle between the sliding surface  331  and the center axis O 1 ) is less than 90°, and is preferably about 30° to 85°, more preferably about 45° to 80°. 
     This permits the protector  9  to be released from the outer needle hub  3  more smoothly. 
     Here, in the process of moving the inner needle hub  5  in the proximal direction relative to the protector  9  starting from the assembled condition and thereby pulling the inner needle  4  out of the outer needle  2 , it is preferable to set the inclination angle θ so as to satisfy the following condition, let the force required in the first state of the coupling member  92  be F 1 , and let the force required during the period from the moment of movement of the needle point  41  of the inner needle  4  to the proximal side of the coupling member  92  until the projection piece  924  and the rib  33  are disengaged from each other, that is, during the shift of the coupling member  92  from the first state to the second state, be F 2 . 
     The condition to be satisfied lies in that F 2  is preferably not more than 2×F 1 , more preferably not more than 1.5×F 1 , and further preferably not more than F 1 . 
     Particularly, it is preferable to set the inclination angle θ so that F 2  and F 1  will be approximately equal. 
     This permits the projector  9  to be released from the outer needle hub  3  more smoothly. 
     Incidentally, most part of the force F 1  is a force against the frictional resistance between the outer peripheral surface of the inner needle  4  and the first part  921  of the coupling member  92 . Besides, most part of the force F 2  is a force against the frictional resistance between the projection piece  924  of the coupling member  92  and the sliding surface  331  of the rib  33 . 
     In addition, while the height of the rib  33  is uniform in this embodiment, the height may gradually decrease along the moving direction in the sliding of the projection piece  924  on the sliding surface  331  of the rib  33 . Where the height of the rib  33  is thus gradually decreased, the coupling member  92  can be brought into the second state more smoothly and assuredly. 
     Incidentally, it is preferable that either one or both of the sliding surface  331  of the rib  33  of the outer needle hub  3  and the opposed surface  926  of the projection piece  924  of the coupling member  92  are coated with a lubricant such as a silicone oil, a surfactant, etc. This results in that the sliding resistance between the projection piece  924  and the sliding surface  331  of the rib  33  is reduced, whereby the projection piece  924  of the coupling member  92  can slide along the sliding surface  331  of the rib  33  more smoothly. 
     In addition, a portion of the first part  921  of the coupling member  92  which makes contact with the outer peripheral surface of the inner needle  4  is also preferably coated with a lubricant. This reduces the frictional resistance between the outer peripheral surface of the inner needle  4  and the first part  921 , ensuring that the inner needle  4  can be moved relative to the protector  9  more smoothly. 
     Meanwhile, as shown in  FIGS. 2 and 5 , in this indwelling needle assembly  1 , the inner needle hub  5  is provided with the finger hold  54  at its proximal portion. The finger hold  54  includes: a projected part  55  which is projected to the proximal side relative to a proximal end face  53  of the inner needle hub body part  50  and which is formed from a material less liable (than the inner needle hub body part  50 ) to slip on a medical glove when the thumb of the gloved hand is in contact with the finger hold  54  (the proximal portion of the inner needle hub  5 ); and a portion of the proximal end face  53  where the projected part  55  is not provided. Hereinafter, the medical glove will also be referred to simply as “glove.” 
     Here, at the time of setting the outer needle  2  of the indwelling needle assembly  1  indwelling in a patient, a clinician (user) wears gloves, holds the indwelling needle assembly  1  in the assembled condition with his or her fingers, and thereby performs a puncturing operation of puncturing the patient&#39;s blood vessel or the like with the outer needle  2  and the inner needle  4 . Besides, at the time of this puncturing operation, the clinician may hold the indwelling needle assembly  1  by a method as shown in  FIG. 3 , for example. 
     This holding method of manner is herein referred to as “wing port holding,” in which the thumb is put in contact with the finger hold  54  (the proximal portion of the inner needle hub  5 ), and one of the remaining fingers (in the configuration shown in the figure, the middle finger) is put in contact with the distal side of the indwelling needle assembly  1 , specifically, with the wing  12   a  of the outer needle hub  3 , whereby the indwelling needle assembly  1  is held so as to be pinched in the longitudinal direction thereof. Incidentally, even in the case of using an indwelling needle assembly which is not provided with the wings  12   a,    12   b,  the above-mentioned wing port holding can be achieved by a method in which, for example, the middle finger is put in contact with the distal side of the indwelling needle assembly, such as the distal end of the outer needle hub, a tapered surface of a distal portion of the outer needle hub, etc. 
     In the case of holding the indwelling needle assembly  1  by the wing port holding as above, it is possible, by providing the projected part  55 , to prevent the thumb of a gloved hand from slipping off the finger hold  54  (the proximal end of the inner needle hub  5 ). As a result, the puncturing operation can be performed easily and safely. 
     The projected part  55  is fixed to the proximal end face  53 . Examples of the method for fixing the projected part to the proximal end face  53  include such methods as fitting, fusing, insert molding, adhesion with an adhesive, etc. and combinations thereof. 
     In addition, the projected part  55  is protuberant from a part of the proximal end face  53 . In the configuration shown in the figures, the projected part  55  is circular in shape as viewed in the direction of the center axis O 1  of the inner needle  4 , and the projected part  55  is disposed at a central portion of the proximal end face  53 . This ensures that a thumb can be more securely prevented from slipping off the finger hold  54 . 
     The dimensions of the projected part  55  are not particularly limited, but may be appropriately set according to various conditions. Preferably, however, the value of the ratio “a/b” of “a” to “b” is in the range from about 0.01 to 0.8, more preferably from about 0.1 to 0.3, where “a” is the area of projection (projection area) of the projected part  55  onto a plane perpendicular to the center axis o 1  of the inner needle  4 , and “b” is the area of projection, onto the aforementioned plane, of the whole part of the finger hold  54  (the whole part of the proximal end face  53 ), that is, the area of projection of the projected part  55  and the part of the proximal end face  53  where the projected part  55  is not provided. 
     The height (the length along the direction of the center axis O 1 ) of the projected part  55  is preferably about 0.1 to 5 mm, more preferably about 0.3 to 2 mm. In addition, the projection area “a” of the projected part  55  is preferably about 0.2 to 20 mm 2 , more preferably about 0.7 to 13 mm 2 . 
     Here, the medical gloves are required to be flexible, fit the hands well, and have strength. Thus, the gloves are preferably formed from such a material as polyvinyl chloride (PVC), natural rubber latex, nitrile rubber, etc. In this indwelling needle assembly  1 , depending on the material constituting the gloves, a material less liable to slip on the glove is appropriately selected as the material for constituting the projected part  55 , whereby the thumb of the gloved hand is prevented from slipping off the finger hold  54 . 
     In addition, the material constituting the projected part  55  is not particularly limited, insofar as it is a material less liable (than the inner needle hub body part  50 ) to slip on the glove, and the material may be appropriately selected depending on various conditions. Preferable examples of the material constituting the projected part  55  include isoprene rubber, silicone rubber, ethylene-vinyl acetate copolymer, polyurethane, etc., among which more preferred are isoprene rubber and silicone rubber. 
     Besides, the proximal end face (the portion on the proximal end face side) of the projected part  55  is preferably formed with a plurality of minute recesses and projections (not shown). By this, slippage of the thumb relative to the finger hold  54  can be prevented more securely. The method of forming the minute recesses and projections is not particularly limited. Examples of the method which can be used here include embossing, matte finish, shot blasting (e.g., collision of silica particles against the work), etc. 
     In addition, the inner needle hub body part  50  of the inner needle hub  5  is required to be easy to assemble with the inner needle  4  and other components such as the protector  9 , and to have such a degree of transparency that the flashback of blood can be seen therethrough. Besides, the inner needle hub body part  50  is required to be comparatively hard, since it is used also as a holding part. 
     Preferable examples of the material constituting the inner needle hub body part  50  include polycarbonate, polypropylene, etc. When polycarbonate is used, the inner needle hub body part  50  is excellent in transparency, is hard, can be adhered by use of a solvent, and permits easy assembly. When polypropylene is used, the inner needle hub body part  50  is excellent in chemical resistance, and is good in bio-compatibility. 
     Incidentally, the length (distance) L between the distal end of the outer needle hub  3  and the proximal end of the projected part  55  (finger hold  54 ) in the indwelling needle assembly  1  in the assembled condition is preferably about 20 to 80 mm, more preferably about 30 to 60 mm. This permits the wing port holding to be achieved easily. 
     Now, an example of the method of using the indwelling needle assembly  1  (a case of puncturing a blood vessel) (operation) will be described in detail below. 
     It is presumed that the clinician wears medical gloves. It suffices for this step to be performed before the puncturing operation (described later) is conducted. 
     [1] The indwelling needle assembly  1  is prepared, it is put into the assembled condition (see  FIGS. 1 ,  2 ,  5 ,  6  and  9 ), and a connector equipped at an end portion of an infusion line is preliminarily connected to the connector  72  so that an infusion liquid can be supplied from the infusion line. 
     Incidentally, in this instance, a predetermined part of the tube  7  or the infusion line is preliminarily pinched, for example, with a clamp (an example of flow path opening/closing means), thereby closing the lumen of the tube  7  or the infusion line. 
     [2] Next, closure of the tube  7  or the infusion line with the clamp or the like is released, whereby the infusion liquid from the infusion line is introduced through the tube  7  into the outer needle hub  3 . 
     The infusion liquid thus introduced into the outer needle hub  3  fills up the branch flow path  32  and the flow path  31  on the distal side relative to the seal member, and is led into the lumen  21  of the outer needle  2 , whereby the lumen  21  of the outer needle  2  is primed with the infusion liquid. In this instance, part of the infusion liquid flows out via the tip opening  22  of the outer needle  2 . 
     [3] When the priming is completed in this manner, the tube  7  or the infusion line is again closed with a clamp or the like provisionally, and the indwelling needle assembly  1  is held by the above-mentioned wing port holding. 
     [4] Subsequently, the outer needle  2  and the inner needle  4  integrated with each other are made to puncture a patient&#39;s blood vessel (vein or artery) (living body). 
     When the outer needle  2  is securely inserted into the blood vessel, the internal pressure in the blood vessel (blood pressure) causes blood to flow back in the proximal direction through the inner needle  4  and through the lumen  21  of the outer needle  2 , and this blood flow can be confirmed in at least one location, where inside visibility is secured, of the outer needle  2 , the outer needle hub  3 , the inner needle hub  5  and the tube  7 . 
     After the backward blood flow is confirmed, the outer needle  2  is further advanced by a minute distance in the distal direction along the inner needle  4  and with the inner needle  4  as a guide. 
     Besides, at the time of puncturing the blood vessel in this manner, the lumen  21  of the outer needle  2  has already been primed with the infusion liquid, so that erroneous penetration of a bubble or bubbles into the blood vessel is securely prevented and, hence, safety is extremely high. 
     [5] After the outer needle  2  has captured (securely punctured) the blood vessel (after the outer needle  2  has been moved to a target position), the outer needle  2  or the outer needle hub  3  is fixed by one hand, and the inner needle hub  5  is gripped by the other hand and pulled in the proximal direction. By this, a series of operations (motions) from withdrawal of the inner needle  4  from the outer needle  2  to the release of the protector  9  from the outer needle hub  3  are carried out sequentially and continuously. Specifically, first, the inner needle  4  is moved in the proximal direction, and is drawn out of the outer needle  2 . 
     [6] When the inner needle  4  is further moved in the proximal direction and the needle point  41  is passed through the inside of the slit, the seal member having the self-closing property closes the slit by its own elastic force. This prevents leakage of liquid through the slit from occurring, and ensures that the sterility in the outer needle hub  3  and the infusion line is secured. 
     [7] When the inner needle  4  is further moved in the proximal direction and the needle point  41  reaches the proximal side of the first part  921  of the coupling member  92 , as shown in  FIGS. 7 and 10 , the coupling member  92  opens under its own elastic force, and is pulled and moved in the proximal direction through the connecting member  20 , to be brought into the second state. 
     In this case, as above-mentioned, the direction in which the projection piece  924  is moved due to restoration of the coupling member  92  is substantially perpendicular to the center axis O 1  of the inner needle  4 . In this instance, since the protector  9  is pulled and moved in the proximal direction through the connecting member  20 , the coupling member  92  is also moved in the proximal direction attendant on the proximal movement of the protector  9 . As a result, the projection piece  924  is slid along the sliding surface  331  of the rib  33 , and the coupling member  92  is brought into the second state. When the coupling member  92  is thus brought into the second state, any distal returning movement again of the needle point  41  of the inner needle  4  is impossible, since the needle point  41  is in abutment on the shutter part  925  of the coupling member  92 . 
     [8] Further, the inner needle hub  5  is moved in the proximal direction, whereby the protector  9  is pulled and moved in the proximal direction through the connecting member  20 , to be separated (released) from the outer needle hub  3 . 
     Since the connecting member  20  has such a length that the needle point  41  is accommodated in the protector body  91  when the connecting member  20  is in its maximally extended state, the protector  9  can be securely prevented from slipping off from the needle point  41 . Accordingly, the condition where the needle point  41  is covered by the protector  9  can be maintained assuredly. 
     After the inner needle  4  is drawn out of the outer needle  2  in this manner, the inner needle  4  and the inner needle hub  5  are useless and, hence, are put to disposal. 
     Thus, the inner needle  4  has its needle point  41  covered by the protector  9 . Particularly, the possibility that the needle point  41  might move in the distal direction beyond the shutter part  925  of the coupling member  92  to protrude from the distal end of the protector  9  is utterly eliminated. Accordingly, an accident that a person in charge of disposal or the like might stick the needle point  41  in his or her finger or the like by mistake can be prevented from occurring. 
     [9] Next, the wings  12   a  and  12   b  are fixed to the patient&#39;s skin by a pressure sensitive adhesive tape or the like, the closure of the tube  7  or the infusion line with the clamp is released, and supply of the infusion liquid is started. 
     The infusion liquid supplied from the infusion line flows through the respective inner cavities of the connector  72 , the tube  7 , the outer needle hub  3  and the outer needle  2 , to be infused into the patient&#39;s blood vessel. 
     As has been described above, according to the indwelling needle assembly  1 , the thumb of the hand holding the indwelling needle assembly  1  in the wing port holding mode can be prevented (or restrained), by the projected part  55 , from slipping off the finger hold  54  (the proximal end of the inner needle hub  5 ). This permits the clinician (user) to concentrate on the intended procedure and to carry out the puncturing operation easily and safely. 
     Incidentally, other configuration examples of the projected part  55  in this embodiment include those shown in  FIGS. 11A to 11F  and  FIGS. 12G to 12K . 
       FIGS. 11A to 12K  illustrate other configuration examples in the indwelling needle assembly in this embodiment, wherein  FIGS. 11A to 11F  and  FIGS. 12G to 12J  are rear views of the indwelling needle assembly, and  FIG. 12K  is a sectional view of a projected part. Incidentally, in the following description, the upper side in  FIGS. 11A to 11F  and  FIGS. 12G to 12J  will be referred to as “upper (up)” and the lower side as “lower (down).” Besides, the left side in  FIG. 12K  will be referred to as “distal,” the right side as “proximal,” the upper side as “upper (up)” and the lower side as “lower (down).” 
     In the indwelling needle assembly  1  shown in  FIG. 11A , the projected part  55  is protuberant from a part of the proximal end face  53 , and is disposed at a central portion of the proximal end face  53 . The projected part  55  is in the shape of a circular ring, as viewed in the direction of the center axis O 1  of the inner needle  4 . In other words, the projected part  55  is provided in its central portion with a bottomless recess  551 . 
     In the indwelling needle assembly  1  shown in  FIG. 11B , the projected part  55  is protuberant from a part of the proximal end face  53 , and is disposed at a central portion of the proximal end face  53 . The projected part  55  is in the shape of a half of a circular ring, that is, a curved line with a recess on the lower side, as viewed in the direction of the center axis O 1  of the inner needle  4 . 
     In the indwelling needle assembly  1  shown in  FIG. 11C , the projected part  55  is protuberant from a part of the proximal end face  53 , and is disposed at a central portion of the proximal end face  53 . The projected part  55  is in the shape of a straight line segment, as viewed in the direction of the center axis O 1  of the inner needle  4 . 
     In the indwelling needle assembly  1  shown in  FIG. 11D , the projected part  55  is protuberant from a part of the proximal end face  53 , and is disposed at a central portion of the proximal end face  53 . The projected part  55  is in the shape of a right-angled isosceles triangle, as viewed in the direction of the center axis O 1  of the inner needle  4 . Besides, the right-angled vertex of the projected part  55  is so positioned as to face the lower. 
     In the indwelling needle assembly  1  shown in  FIG. 11E , the projected part  55  is protuberant from a part of the proximal end face  53 , and is disposed at a central portion of the proximal end face  53 . The projected part  55  is in the shape of a square, as viewed in the direction of the center axis O 1  of the inner needle  4 . Besides, the projected part  55  may be in a polygonal shape with or more than five angles. 
     In the indwelling needle assembly  1  shown in  FIG. 11F , the projected part  55  is protuberant from a part of the proximal end face  53 , and is disposed at a central portion of the proximal end face  53 . The projected part  55  is in the shape of a cross, as viewed in the direction of the center axis O 1  of the inner needle  4 . 
     In the indwelling needle assembly  1  shown in  FIG. 12G , the projected part  55  is protuberant from a part of the proximal end face  53 , and is disposed at a central portion of the proximal end face  53 . The projected part  55  is in such a shape as to extend radially, as viewed in the direction of the center axis O 1  of the inner needle  4 . Specifically, the projected part  55  is composed of a plurality of unit projected parts  552  arranged to extend radially from the center of the proximal end face  53 , and a recess  553  is provided in a central portion of the projected part  55 . 
     In the indwelling needle assembly  1  shown in  FIG. 12H , the projected part  55  is protuberant from a part of the proximal end face  53 , and is disposed at a central portion of the proximal end face  53 . The projected part  55  is in the shape of a circular ring (ring) from which an upper-side portion (a part) has been removed, as viewed in the direction of the center axis O 1  of the inner needle  4 . 
     In the indwelling needle assembly  1  shown in  FIG. 12I , the projected part  55  is protuberant from a part of the proximal end face  53 , and is disposed at a central portion of the proximal end face  53 . The projected part  55  is in the shape of a circle, as viewed in the direction of the center axis O 1  of the inner needle  4 . In addition, an upper-side portion (the portion which is hatched in the figure) of the projected part  55  is colored in a color different from the color of the remaining lower-side portion of the projected part  55 . 
     In the indwelling needle assembly  1  shown in  FIG. 12J , the projected part  55  is protuberant from a part of the proximal end face  53 . This projected part  55  is composed of two unit projected parts  554  and  555 . 
     The unit projected part  554  is in the shape of a half of a circular ring, that is, a curved line with a recess on the lower side, as viewed in the direction of the center axis O 1  of the inner needle  4 . This unit projected part  554  is disposed on the upper side in the proximal end face  53  along the outer circumference of the proximal end face  53 . 
     On the other hand, the unit projected part  555  is in the shape of a circle, as viewed in the direction of the center axis O 1  of the inner needle  4 . This unit projected part  555  is disposed on the lower side in the proximal end face  53 . 
     Besides, the length of the unit projected part  554  along the direction of the center axis O 1  is set greater than the corresponding length of the unit projected part  555 , and the proximal end face of the unit projected part  554  is located on the proximal side relative to the proximal end face of the unit projected part  555 . 
     This ensures that when the indwelling needle assembly is held by the wing port holding, the tip side of the thumb comes into contact with the unit projected part  554 , and the pad of the thumb is caught on the unit projected part  555 , so that slippage of the thumb off the finger hold  54  can be prevented more securely. 
     In the indwelling needle assembly  1  shown in  FIG. 12K , the projected part  55  is protuberant from a part of the proximal end face  53 , and is disposed at a central portion of the proximal end face  53 . The projected part  55  is in the shape of a circle, as viewed in the direction of the center axis O 1  of the inner needle  4 . Besides, the projected part  55  is provided with a bottomed recess  556  in its central portion. 
     Here, the projected part  55  may be so configured that its pattern has predetermined information, specifically, its serves as a predetermined mark. For example, the projected parts  55  shown in  FIGS. 11B and 11D  each may be so configured that its lower side indicates a predetermined position (direction). The projected parts  55  shown in  FIGS. 12H and 12I  may be so configured that its upper side indicates a predetermined position. 
     While the indwelling needle assembly according to the present invention has been described above based on the embodiments shown in the drawings, the invention is not limited to the embodiments. The configurations of components can be replaced by arbitrary configurations having equivalent functions. Besides, other arbitrary structures and/or steps may be added to the present invention. 
     Incidentally, the indwelling needle assembly according to the embodiment of the present invention is not limited to those which are to be used by being inserted in a blood vessel, but may also be applied, for example, to those which are to be used by being inserted in a living body such as an abdominal cavity, a thoracic cavity, a lymph vessel, a vertebral canal, etc. 
     Besides, in the embodiment of the present invention, the protector is not limited to the one configured as shown in the drawings, insofar as it can be detachably connected to the outer needle hub. Particularly, there can be used protectors of various configurations that cover at least the needle point of the inner needle upon withdrawal of the inner needle from the outer needle. 
     In addition, in the embodiment of the present invention, the wings  12   a  and  12   b  may be omitted. 
     Besides, in the embodiment of the present invention, the side pipe  37  and/or the tube  7  can be omitted. 
     It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.