Abstract:
The invention provides a needleless injection adapter which can inject medical fluid without using an injection needle, and can completely prevent occurrence of accidental needle sticking to medical staff and a patient and of accidental nosocomial infection. The needleless injection adapter includes: a socket being coupled to a tip of an injector; a duct body with connecting portions to connect with fluid conveying tubes at both ends thereof; a movable member with the socket, slidably held on the middle of a surface of the duct body. A first hole extending to the socket and a second hole extending through the duct body are opposed to each other on a face where the movable member and the duct body are slidable in contact with each other. The two holes are connected or disconnected in accordance with the position of the movable member.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2004-007348, filed on Jan. 14, 2004, the entire contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a needleless injection adapter which is disposed in the middle of an extracorporeal blood circuit used for treatment for renal failure and the like, or with a blood or fluid transfusion set, in order to inject medical fluid into a patient or collect blood from a patient with the extracorporeal blood circuit at appropriate time.  
         [0004]     2. Description of the Related Art  
         [0005]     A conventional injection adapter is generally provided in the middle of an extracorporeal blood circuit used for treatment for a patient of renal failure, and in the middle of a blood or fluid transfusion set. The conventional injection adaptor, as shown in  FIG. 13 , is provided with a duct body  73  having connecting portions  72  to connect with the fluid conveying tubes  71  at the ends thereof. An erect duct  74  is provided in the middle of the top face of the duct body  73 . A cap  76  is formed in the top end of the erect duct  74 , holding a rubber plug  75  pierced with an injection needle  80   b  in such a manner as to expose a part of the rubber plug  75 .  
         [0006]     In the conventional injection adapter, the rubber plug  75  exposed from the cap  76  is pierced with the injection needle  80   b  coupled to a tip  80   a  of an injector  80  at its base end. Medical fluid is injected by pushing a plunger as indicated by the arrow. Upon pulling the injection needle  80   b  out of the rubber plug  75  after the injection of the medical fluid, a hole of the needle is immediately clogged by the elasticity of the rubber. Thus, the injection operation of the medical fluid does not cause any trouble over original treatment operation, in which a patient is connected to an extracorporeal blood circuit or a blood or fluid transfusion set.  
         [0007]     After the medical fluid injection, the injection needle is pulled out of the rubber plug  75  as described above, and a protective cap (not illustrated) is immediately put thereon, and the injection needle with the protective cap thereon is detached from the injector from segregated discarding. However, there is a possibility that an operator may accidentally stick the tip of the injection needle into his/her finger when putting the injection needle on the protective cap, and may get infected from infectious blood adhering to the needle.  
       SUMMARY OF THE INVENTION  
       [0008]     In view of solving the above-identified problems, an object of the present invention is to provide a needleless injection adapter which can inject medical fluid without use of an injection needle and completely prevents occurrence of accidental needle sticking into medical staff and a patient and of accidental nosocomial infection.  
         [0009]     To achieve the foregoing object, a needleless injection adapter according to one aspect of the present invention includes a duct body, a socket, a movable member, and biasing member. The duct body has connecting portions to connect with fluid conveying tubes at both ends thereof. The movable member having the socket, to which a tip of an injector is coupled, is slidably held in the middle of a surface of the duct body. Two holes, one extending to the socket and the other one extending through the duct body, are disposed oppositely to each other, in a surface on which the movable member and the duct body are slidably in contact with each other. The biasing member biases the movable member in a direction where the two holes are misaligned with each other. With the tip of the injector without a needle coupled to the socket, a movement of the movable member connects the two holes to carry out injection. After the injection, the movable member is automatically displaced to misalign the holes.  
         [0010]     According to the needleless injection adapter of the present invention, it is possible to carry out injection by coupling the tip of the injector without a needle to the socket and moving the movable member to connect the holes. It is also possible to misalign the holes by automatically displacing the movable member after the injection. Therefore, the needleless injection adapter has a beneficial effect of quickly completing the medical fluid injection operation.  
         [0011]     In another aspect of the needleless injection adapter according to the present invention, a needleless injection adapter includes a duct body, a socket, a slidable member, and biasing member. The duct body has connecting portions to connect with fluid conveying tubes at both ends thereof, and a vertical hole to connect the socket to the inside of the duct body. The socket, to which the tip of the injector is coupled, is provided in the middle of a surface of the duct body. The slidable member divides the vertical hole, and is provided with at least one connection hole which connects upper and lower vertical holes divided by the slidable member. The biasing member biases the slidable member in a direction where the connection hole shifts from the upper and lower vertical holes. By coupling the tip of the injector without a needle to the socket, and sliding the slidable member, the upper and lower vertical holes are connected to carry out injection. After the injection, the slidable member is automatically displaced to divide the upper and lower vertical holes.  
         [0012]     According to the foregoing needleless injection adapter, it is possible to carry out injection by coupling the tip of the injector without a needle to the socket, and sliding the slidable member to connect the upper and lower vertical holes. It is also possible to divide the upper and lower vertical holes by automatically displacing the slidable member after the injection. Therefore, the needleless injection adapter has a beneficial effect of quickly completing the medical fluid injection operation.  
         [0013]     In another aspect of the needleless injection adapter according to the present invention, the biasing member is fixed on the duct body so that the biasing member accumulates return force to be elastically deformed in a state that the socket gets in communication with the inside of the duct body by the movement of the movable member or the sliding of the slidable member. When the socket and the inside of the duct body are communicated with each other, the biasing member accumulates the return force. After the injection, releasing the accumulated return force at the position where they are in communication brings the socket and the inside of the duct body into a non-communication state.  
         [0014]     This makes it possible for the biasing member to accumulate the return force only by connecting the socket to the inside of the duct body. It is beneficial that the socket is immediately disconnected from the inside of the duct body by the return force of the biasing member after the completion of the injection, without any manipulation of an operator.  
         [0015]     In further aspect of the needleless injection adapter according to the present invention, the socket is provided with a stopper which retains the state that the socket is in communication with the inside of the duct body. When the socket gets in communication with the inside of the duct body by moving the movable member or sliding the slidable member, and the tip of the injector is coupled to the socket, the stopper operates to retain the state until it is released.  
         [0016]     According to the foregoing needleless injection adapter, moving the movable member or sliding the slidable member to get the socket in communication with the inside of the duct body after the coupling of the tip of the injector to the socket allows the stopper to operate to retain the communication state until the completion of injection without any manipulation of an operator. With the needleless injection adapter connected to another fluid transfusion set and the like, it is beneficial that continuous injection is enabled.  
         [0017]     In further aspect of the needleless injection adapter according to the present invention, the needleless injection adapter includes a duct body, a socket, a rotatable member, a spring member, and a sound emission member and/or a tactile member. The rotatable member with the socket for the injector is slidably disposed on a side face of the duct body. When the rotatable member is rotated by a predetermined angle, a small hole extending to the socket of the rotatable member is aligned with another small hole formed in the side face of the duct body. The spring member biases the socket in the direction where the small holes are misaligned with each other. The sound emission member and/or the tactile member provided in the socket snaps a tip end of the spring member at a point where the small holes are aligned, so that it is possible to confirm that the injection is normally done.  
         [0018]     This makes it possible to align the small hole extending to the socket of the rotatable member with another small hole extending through the side face of the duct body, by coupling the socket erected on the rotatable member to the tip of the injector without a needle to rotate the rotatable member, whereby the operator is surely informed of the alignment position with a sound or an impact by snapping the tip end of the spring member. Therefore, it is advantageous that the operator is able to smoothly and securely carry out the injection since he or she can operate the injector with the rotatable member in rotation upon hearing the sound or impact. Also, when the operator loosens his/her hold after the injection, the rotatable member is automatically returned to a position in which the small holes are misaligned with each other, due to the action of the spring member. This eliminates the need for the operator to return the rotatable member to the misalignment position of the small holes. This also enables the operator to pull the tip of the injector out of the socket at ease. Accordingly, the needleless injection adapter provides various beneficial effects.  
         [0019]     In further aspect of the needleless injection adapter according to the present invention, the sound emission member and/or the tactile member includes the tip end of the spring member whose base end is held by the duct body, and a projection or a recess on the side face of the socket with which the tip end in contact. The sound emission member and/or the tactile member are so structured as to surely emit a sound or an impact at the point where the small holes are aligned.  
         [0020]     According to the foregoing needleless injection adapter, the sound or impact is emitted when the tip end of the spring member makes contact with the projection or the recess on the side face of the socket. Thus, it is possible to easily make the emission of the sound or the impact coincide with the alignment of the small holes, so that the operator is beneficially informed of the alignment of the small holes with precision.  
         [0021]     In another aspect of the needleless injection adapter according to the present invention, the needleless injection adapter is provided with a position retaining member which retains the rotatable member to rotate against the spring force of the spring member, in such a position that the small holes are aligned with each other. The alignment of the small holes is continuously maintained.  
         [0022]     According to the foregoing needleless injection adapter, the position retaining member in the rotatable member can continuously retain the alignment of the small holes during continuous medical fluid injection, if medical fluid is continuous injected for many hours with use of a continuous medical fluid injector coupled to the socket of the rotatable member, for example. Also, without the position retaining member, the action of the spring member automatically misaligns the small holes. Therefore, it is advantageous that the needleless injection adapter is connected to and disconnected from the continuous medical fluid injector at ease. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]     The nature, principle, and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings in which like parts are designated by identical reference numbers, in which:  
         [0024]      FIG. 1  is a perspective view of a needleless injection adapter according to a first embodiment of the present invention;  
         [0025]      FIG. 2  is a front sectional view of the needleless injection adapter according to the first embodiment, in which biasing member is elastically deformed with accumulated return force;  
         [0026]      FIG. 3  is a front sectional view of the needleless injection adapter according to the first embodiment, in which the return force of the biasing member brings a socket and the inside of a duct body into a non-communication state;  
         [0027]      FIG. 4  is an enlarged sectional view of the needleless injection adapter with a stopper according to the first embodiment;  
         [0028]      FIG. 5  is a perspective view of a needleless injection adapter according to a second embodiment of the present invention;  
         [0029]      FIG. 6  is a front sectional view of the needleless injection adapter according to the second embodiment, in which biasing member is elastically deformed with accumulated return force;  
         [0030]      FIG. 7  is a front sectional view of the needleless injection adapter according to the second embodiment, in which the return force of the biasing member brings a socket and the inside of a duct body into a non-communication state;  
         [0031]      FIG. 8  is an enlarged sectional view of the needleless injection adapter with a stopper according to the second embodiment;  
         [0032]      FIG. 9  is a perspective view of a needleless injection adapter according to a third embodiment of the present invention;  
         [0033]      FIG. 10  is an enlarged sectional view of the needleless injection adapter according to the third embodiment of the present invention;  
         [0034]      FIG. 11  is a sectional view of the needleless injection adapter according to the third embodiment, in which small holes are misaligned with each other;  
         [0035]      FIG. 12  is a sectional view of the needleless injection adapter according to the third embodiment, in which the small holes are aligned with each other; and  
         [0036]      FIG. 13  is a perspective view showing a conventional injection adapter with an injection needle. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0037]     The present invention will be hereinafter described on the basis of embodiments shown in drawings.  
       First Embodiment  
       [0038]     A needleless injection adapter  100  according to a first embodiment of the present invention will be described with reference to FIGS.  1  to  4 .  
         [0039]     The needleless injection adapter  100  according to the first embodiment includes a duct body  1  having the connecting portions  3  of fluid conveying tubes  2  at both ends thereof, and a tubular member  4  which is integrally superposed on the middle of a surface of the duct body  1 . The tubular member  4  is orthogonal to the duct body  1  in  FIG. 1 , but the tubular member  4  may cross obliquely or in parallel with the duct body  1 . The fluid conveying tubes  2  connect a patient to an extracorporeal blood circuit (not illustrated) or a vial of a blood or fluid transfusion set.  
         [0040]     A movable member  5  is movably held in the tubular member  4 , so that it is slidably in contact with a surface of the duct body  1 . The movable member  5  is provided with a socket  6  to which a tip  80   a  of an injector  80  is coupled. The socket  6 , as shown in  FIG. 2 , is exposed through a guide groove  7  which is provided in the top face of the tubular member  4 . The guide groove  7  regulates the moving direction and moving range of the socket  6 .  
         [0041]     A hole  8  is formed in the bottom face of the movable member  5  (a sliding surface on the duct body  1 ) and extends to the socket  6 , and a hole  9  is formed in the bottom face of the tubular member  4  (a sliding surface on the movable member  5 ) and extends through the duct body  1 . These facing two holes  8  and  9 , as shown in  FIG. 2 , are aligned with each other (a communication state) in a position where the movable member  5  is moved along the guide groove  7 . The holes  8  and  9 , as shown in  FIG. 3 , are misaligned with each other (a non-communication state) in another position.  
         [0042]     To connect or not to connect the two holes  8  and  9  in a highly fluid-tight manner, as shown in the drawings, elastic material (soft plastic material or rubber material) D with a hole corresponding with the hole  8  may be fitted in the bottom face of the movable member  5 . Elastic material (not illustrated) may be fitted on the bottom face of the tubular member  4 , as a matter of course.  
         [0043]     In this embodiment, the two holes  8  and  9  are in the communication state when the socket  6  of the movable member  5  is erect with making contact with a groove edge  7   a  of the guide groove  7 , and are in the non-communication state when the socket  6  of the movable member  5  is oblique with making contact with the other groove edge  7   b  of the guide groove  7 . The two holes  8  and  9 , however, may be in the communication state when the socket  6  is oblique, and may be in the non-communication state when the socket  6  is erect.  
         [0044]     The moving direction and range of the movable member  5  is in the circumferential direction of the tubular member  4  in an example shown in the drawing. The movable member  5  may slide inside the tubular member  4  in an axial direction, or in the circumferential direction in combination with the axial direction.  
         [0045]     The socket  6  is biased by biasing member  10  in such a direction that the hole  8  of the movable member  5  is misaligned with the hole  9  of the duct body  1 . The biasing member  10  extends from an end portion of a fixing member  11  whose cross section has the shape of “U”. The fixing member  111  fixes the duct body  1  by which pinching it with the tubular member  4 . An extended end  10   a  of the biasing member  10  makes contact with a surface of the socket  6 . When pushing force as shown by the arrow A of  FIG. 2  is applied to the socket  6  to align both holes  8  and  9  with each other, the biasing member  10  is elastically deformed with accumulated return force. When the pushing force is loosened, on the other hand, the movable member  5  obliquely moves by the return force (the arrow B) of the biasing member  10 , as shown in  FIG. 3 , to bring both holes  8  and  9  back into the non-communication state.  
         [0046]     The socket  6  or  26  is provided with a stopper  31  which keeps the communication between the socket  6  or  26  and the inside of the duct body  1  or  21  (refer to  FIG. 4 ). The stopper  31  prevents the communication between the hole  8  extending to the socket  26  and the hole  9  extending through the duct body  1  from being released before the completion of injection.  
         [0047]     According to this embodiment, the stopper  31  is so structured that the socket  26  can be pushed in a downward direction against the spring force of a spring  32  while being coupled to the tip  80   a  of the injector  80 . Thus, a slider  33  integral with the socket  26  is inserted into the hole  9  formed in the bottom face of the tubular member  4 . This insertion is retained until the completion of injection, in which the tip  80   a  of the injector  80  is pulled out of the socket  26  by the pushing force of the biasing member  10 .  
         [0048]     In the following, the operation of the needleless injection adapter  100  according to the first embodiment will be described.  
         [0049]     First, the needleless injection adapter  100  according to this embodiment is disposed with the fluid conveying tubes  2  of an extracorporeal blood circuit (not illustrated). The socket  6  of the movable member  5  is oblique at first, as shown in  FIG. 3 , so that the hole  8  extending to the socket  6  and the hole  9  extending through the duct body  1  are in the non-communication state to carry out dialysis treatment and the like.  
         [0050]     When it is necessary to inject medical fluid into a patient, the tip  80   a  of the injector  80  containing the medical fluid is coupled to the socket  6  or  26 . Then, since the socket  6  is moved along the guide groove  7  with the injector  80 , the two holes  8  and  9  are brought into the communication state against the biasing member  10 . An operator has to manually keep the communication during the injection, to prevent the return force of the biasing member  10 . With the stopper  31  in the socket  26 , however, it is possible to retain the communication without the manipulation of the operator.  
         [0051]     Then, pushing a plunger of the injector  80  makes it possible to inject the medical fluid into blood (transfused fluid) which flows through the fluid conveying tubes. In completing this injection operation, the tip  80   a  of the injector  80  is pulled out of the socket  6 , so that the return force of the biasing member  10  brings the two holes  8  and  9  into the non-communication state.  
         [0052]     This completes a series of medical fluid injection operation without any effect given on original treatment operation in which the patient is connected to the extracorporeal blood circuit (the blood or fluid transfusion set). As a matter of course, the needleless injection adapter according to this embodiment is applicable to blood collection (suction into the injector), in addition to the injection of the medical fluid.  
         [0053]     The stopper  31  is disposed inside the socket  26  according to the foregoing embodiment but it may be disposed in another place. The duct body  1  may be provided with, for example, a lever for regulating the return force of the biasing member  10  which is elastically deformed by accumulating the return force.  
       Second Embodiment  
       [0054]     A needleless injection adapter  200  according to a second embodiment of the present invention will be described with reference to FIGS.  5  to  8 .  
         [0055]     The needleless injection adapter  200  according to the second embodiment is provided with a duct body  21  having connecting portions  23  of the fluid conveying tubes  2  at both ends thereof, and a cabinet  24  which is integrally formed on a surface in the middle of the duct body  21 . In  FIG. 5 , the cabinet  24  is provided around the perimeter of the duct body  21 .  
         [0056]     A socket  26 , to which the tip  80   a  of the injector  80  is coupled, is provided in the top face of the cabinet  24 . The socket  26  is connected to the inside of the duct body  21  through a vertical hole  25 . The vertical hole  25  is vertically divided by a slidable member  27  which is slidably inserted into a horizontal hole  24   a  penetrating both ends of the cabinet  24 . A connection hole  28  is formed in the slidable member  27  to connect the divided upper and lower vertical holes  25 . The number of the connection hole  28  is one in the drawing but it is not limited thereto. The connection hole  28  is a perfect circle in shape in general, but it does not always have to be the perfect circle.  
         [0057]     In sliding the slidable member  27  as shown by the arrow C of  FIG. 6 , the connection hole  28  in the slidable member  27  is aligned with the vertical hole  25  (communication state) which connects the socket  26  to the inside of the duct body  21 . In sliding the slidable member  27  as shown by the arrow D of  FIG. 7 , the connection hole  28  shifts from the vertical hole  25  (non-communication state).  
         [0058]     The vicinity of the connection hole  28  of the slidable member  27  or the whole of the slidable member  27  may be made of elastic material (soft plastic material or rubber material), in order to connect or not to connect the connection hole  28  to the vertical hole  25  in a highly fluid-tight manner. The edge of the vertical hole  25  may be made of elastic material (not illustrated).  
         [0059]     One end of the slidable member  27  is provided with a handle  27   a , and the other end  27   b  thereof slightly protrudes from the horizontal hole  24   a . The protruding end  27   b  makes contact with biasing member  29  which biases the slidable member  27  so as to shift the connection hole  28  of the slidable member  27  from the vertical hole  25 . The biasing member  29  extends from an end portion of a fixing member  30  with a U-shaped cross section which fixes the cabinet  24  by pinching it with the duct body  21 . When the handle  27   a  provided in one end of the slidable member  27  is pressed as shown by the arrow C of  FIG. 6 , to align the hole  28  with the vertical hole  25 , the biasing member  29  is elastically deformed with accumulated return force. In loosening the pressing force, on the other hand, the biasing member  29  slides the slidable member  27  by the return force (the arrow D) as shown in  FIG. 7 , so that both the holes  28  and  25  are brought into the non-communication state.  
         [0060]     The socket  26  is provided with a stopper  31  which keeps the communication between the socket  26  and the inside of the duct body  21  (refer to  FIG. 8 ). The stopper  31  prevents the communication between the connection hole  28  of the slidable member  27  and the vertical hole  25  from being released before the completion of injection.  
         [0061]     The stopper  31  is structured so that the socket  26  presses a spring  32  in a downward direction against the spring force of the spring  32  while coupled to the tip  80   a  of the injector  80 . Thus, a slider  33  integral with the socket  26  is inserted into the hole  28  of the slidable member  27 . This insertion is retained until the completion of injection, in which the tip  80   a  of the injector  80  is pulled out of the socket  26  by the pressing force of the biasing member  29 .  
         [0062]     The operation of the needleless injection adapter  200  according to the second embodiment will be described in the following.  
         [0063]     First, the needleless injection adapter  100  or  200  according to the first or second embodiment is disposed in the middle of the fluid conveying tubes  2  of an extracorporeal blood circuit (not illustrated). With the needleless injection adapter  100  according to the first embodiment, the socket  6  of the movable member  5  is oblique at first as shown in  FIG. 3 , so that the hole  8  extending to the socket  6  and the hole  9  extending through the duct body  1  are in the non-communication state. With the needleless injection adapter  200  according to the second embodiment, the slidable member  27  is in an initial position, so that the hole  28  is not in communication with the vertical hole  25  for connecting the socket  26  to the inside of the duct body  21 . Dialysis treatment and the like are carried out in this state.  
         [0064]     When it is necessary to inject medical fluid into a patient, the tip  80   a  of the injector  80  containing the medical fluid is coupled to the socket  6  or  26 . Then, since the slidable member  27  is slid with the injector  80 , the two holes  28  and  25  are brought into the communication state against the biasing member  29 . An operator has to manually keep the communication during the injection operation, to prevent the return force of the biasing member  29 . With the stopper  31  provided in the socket  26 , however, it is possible to retain the communication state without the manipulation of the operator.  
         [0065]     Then, pushing the plunger of the injector  80  makes it possible to inject the medical fluid into blood (transfused fluid) which flows through the fluid conveying tubes. In completing this injection operation, the tip  80   a  of the injector  80  is pulled out of the socket  26 , so that the return force of the biasing member  29  brings the two holes  28  and  25  into the non-communication state. This completes a series of injection operation of the medical fluid without any effect given on original treatment operation in which the patient is connected to the extracorporeal blood circuit (the blood or fluid transfusion set). As a matter of course, the needleless injection adapter according to this embodiment is applicable to blood collection (suction into the injector), in addition to the injection of the medical fluid.  
         [0066]     The stopper  31  is disposed inside the socket  26  according to the foregoing embodiment, but may be disposed in another position. The duct body  21  may be provided with, for example, a lever for regulating the return force of the biasing member  29  which is elastically deformed with accumulated return force.  
       Third Embodiment  
       [0067]     A needleless injection adapter  300  according to a third embodiment of the present invention will be described with reference to FIGS.  9  to  12 .  
         [0068]     In the needleless injection adapter  300  according to the third embodiment, a rotatable member  56  having a socket  55 , to which a tip  54   a  of an injector  54  is coupled, is slidably disposed in a side face  53  of a duct body  52 . When the rotatable member  56  is rotated by a predetermined angle (for example, the rotatable member  56  becomes orthogonal to the duct body  52 ), a small hole  58  extending to the socket  55  of the rotatable member  56  is aligned with a small hole  57  which is formed in the side face  53  of the duct body  52  to extend through the duct.  
         [0069]     The rotatable member  56  refers to what is rotatably contained in a duct  59  which is fixed over the duct body  52  in an orthogonal manner. Thus, the side face  53  of the duct body  52  corresponds to the bottom face of the orthogonal duct  59 . The small hole  57  is formed at one position (in the center) on the bottom face of the orthogonal duct  59 , and extends through the side face  53  of the duct body  52 . Furthermore, the socket  55  erected on the rotatable member  56  protrudes to outside from a through hole  60  which is formed in the top wall of the orthogonal duct  59  along its circumference.  
         [0070]     To secure the air tightness between the small hole  57  extending through the side face  53  of the duct body  52  and the small hole  58  extending to the socket  55  of the rotatable member  56 , a packing member  56   b  may be fitted into a notch groove  56   a  formed in the bottom face of the rotatable member  56 , and the small hole  58  may extend and penetrate the packing member  56   b . In this case, if necessary, means may be provided for preventing the leakage of fluid from a contact surface between the small hole  58  in the rotatable member  56  and the small hole  58  in the packing member  56   b , such as a projection (not illustrated) in the shape of an O-ring to surround the periphery of the small hole  58  in the rotatable member  56 . The projection in the shape of the O-ring may also surround the periphery of the small hole  57  in the duct body  52 , to function as leakage prevention means during the alignment of the small hole  57  with the small hole  58  in the packing member  56   b.    
         [0071]     The side face of the socket  55  erected on the rotatable member  56  is biased and inclined by the tip end  61   a  of a spring member  61  whose base end is held by the duct body  52 . Thus, the small holes  57  and  58  are misaligned from each other in a normal state (refer to  FIG. 10 ). The base end of the spring member  61  extends from ring-shaped members  62  fitted over both end portions of the orthogonal duct body  59 . The base end of the spring member  61  is integral with a base frame  64  supported by pins  63 ,  63   a , and  63   b  which stand near an end of the duct body  52 . The ring-shaped members  62  integral with the base frame  64  are conducive to the coalescence between the divided two portions of the orthogonal duct  59 , the bottom face portion a and the top face portion b.  
         [0072]     The socket  55  of the rotatable member  56  is provided with a sound emission member (and/or tactile member)  6  which snaps the tip end  61   a  of the spring member  61  to emit a sound or an impact at an alignment position of the small holes  57  and  58 . The sound emission member  65  is composed of the tip end  61   a  of the spring member  61  whose base end is held by the duct body  52 , and a projection  65   a  provided on the side face of the socket  55  making contact with the tip end  61   a . Namely, the tip  54   a  of the injector  54  without a needle is coupled to the socket  55  erected on the rotatable member  56  to rotate the rotatable member  56  with the injector  54 , thereby aligning the small holes  57  and  58  with each other. At this time, held by the duct body  52  at the base end, the tip end  61   a  of the spring member  61  falls down from the top of the projection  65   a  provided on the side face of the socket  55 , and is snapped down to tap the side face of the socket  55 , emitting a sound or an impact.  
         [0073]     In other words, when the socket  55  with the injector  54  coupled thereto is rotated from a position illustrated by chain double-dashed lines to a position illustrated by solid lines in the direction of the arrow A in  FIG. 10 , the tip end  61   a  of the spring member  61  runs up on a projection  65   a  and falls down from the top portion thereof in the direction of the arrow B. The tip end  61   a  of the spring member  61  is snapped by the projection  65   a  to tap the side face of the socket  55 , emitting a sound (or an impact). Instead of the projection  65   a , a recess (not illustrated) may be provided in the side face of the socket  55 . In this case, the tip end  61   a  of the spring member  61  falls down into the recess from the end portion of the recess and is snapped.  
         [0074]     The socket  55  of the rotatable member  56  of the needleless injection adapter  300  according to the third embodiment may be provided with a cap  66  which is put on the socket  55  while the needleless injection adapter  300  is in no use. The cap  66  is used as necessary for preventing invasion of bacteria, dust, and the like into the socket  55 . As a matter of convenience, it is preferably configured such that sterilizing fluid can flow through the socket  55  with the cap  66  put on during the sterilization of the needleless injection adapter  300  according to the third embodiment, and after the sterilization the socket  55  is completely sealed by, for example, strongly pressing the cap  66  into the socket  55 .  
         [0075]     Being coupled to a continuous medical fluid injector (not illustrated), the needleless injection adapter  300  according to the third embodiment may be used for continuous medical fluid injection of long hours. In this case, it is necessary to retain an alignment between the small holes  57  and  58  by rotating the rotatable member  56  against the spring force of the spring member  61 . The needleless injection adapter  300  according to the third embodiment is provided with a position retaining member  67 , as an accessory for this purpose, which rotates the rotatable member  56  against the spring force of the spring member  61  to retain an alignment position of the small holes  57  and  58 . The structure of the position retaining member  67  is not specifically limited as long as the position retaining member  67  can retain the rotational position of the rotatable member  56  while the small holes  57  and  58  are aligned with each other. In this embodiment, the position retaining member  67  is a wedge-shaped member shown by chain double-dashed lines which is inserted into the clearance S occurring between the duct body  52  and the rotatable member  56  when the small holes  57  and  58  are aligned with each other. Needless to say, the wedge-shaped member has to be configured not to be easily pulled out from the clearance S when once inserted thereinto, except that the operator pulls it out on purpose.  
         [0076]     In this embodiment, as shown in  FIG. 10 , the wedge-shaped member as an example of the position retaining member  67  is formed in the end of a line member  67   a  extending from the cap  66  put on the socket  55  of the rotatable member  56 . The wedge-shaped member, however, may be formed in another member, for example, in a line member (not illustrated) extending from the base frame  64  of the spring member  61 . The wedge-shaped member may be independent from the cap  66 .  
         [0077]     In the following, the operation of the needleless injection adapter  300  according to the third embodiment will be described with reference to  FIGS. 11 and 12 .  
         [0078]     First, both ends of the duct body  52  of the needleless injection adapter  300  according to the third embodiment are connected to the ends of the fluid conveying tubes  68  of an extracorporeal blood circuit (not illustrated). In the needleless injection adapter  300  according to this embodiment, as shown in  FIG. 11 , the socket  55  of the rotatable member  56  is obliquely biased by the tip end  61   a  of the spring member  61  at first. In other words, the small hole  58  extending to the socket  55  of the rotatable member  56  is misaligned with the small hole  57  extending through the side face  53  of the duct body  52 . In this state, blood flows from the fluid conveying tubes  68  through the duct body  52  without back-flowing through the small holes  57  and  58 , so that dialysis treatment and the like are carried out without problem.  
         [0079]     When it becomes necessary to inject medical fluid into a patient as shown in  FIG. 11 , the tip  54   a  of the injector  54  without a needle is coupled to the socket  55  erected on the rotatable member  56 . Then, as shown in  FIG. 12 , the socket  55  with the injector  54  is rotated against the spring force of the spring member  61  in a vertical direction (in the direction of the arrow). In this case, the tip end  61   a  of the spring member  61  runs up along the projection  65   a  on the side face of the socket  55 . Falling from the top portion of the projection  65   a , the snapped tip end  61   a  of the spring member  61  emits a sound or an impact (the operation of the sound emission member  65 ). A time when the sound or impact is emitted, that is, when the sound emission member  65  operates coincides with the time when the small holes  57  and  58  get aligned with each other, so that upon hearing the sound or impact, an operator clearly confirm the alignment of the small holes  57  and  58 .  
         [0080]     Then, the operator pushes a plunger while vertically holding the socket  55  with the injector  54 , to inject medical fluid into the patient through the fluid conveying tubes  68  with blood flowing through the duct body  52 . Upon completing this injection operation, the operator loosens his/her vertical hold of the injector  54 , allowing it to rotate to be oblique by the spring force of the spring member  61  as shown in  FIG. 11 . Therefore, the small holes  57  and  58  are brought into the non-communication state. Thereafter, the tip  54   a  of the injector  54  is pulled out of the socket  55 . The patient is connected to the extracorporeal blood circuit (the blood or fluid transfusion set) to continue the original treatment. Accordingly, it is possible to complete a series of medical fluid injection operation with smoothness and with safety.  
         [0081]     The needleless injection adapter  300  according to this embodiment is also applied for continuous medical fluid injection of long time by coupling a medical fluid continuous injector (not illustrated) to the socket  55  of the rotatable member  56 . Namely, with the alignment of the small hole  58  and the small hole  57 , as shown in  FIG. 10 , the wedge-shaped clearance S is formed between the duct body  52  and the rotatable member  56 . Inserting the wedge-shaped member  67  into the clearance S makes it possible to continuously retain the alignment of the small holes  57  and  58 .  
         [0082]     The invention is not limited to the above embodiments and various modifications may be made without departing from the spirit and scope of the invention. Any improvement may be made in part or all of the components.