Internal needle

Abstract

An indwelling needle is provided which has a simple structure and is capable of securely mounting a needle tip protective tool on the tip portion of an internal needle. The indwelling needle A consists of an external needle 10 including a cannula 11 and a housing 12 , an internal needle 20 including a metal needle 21 and a hub 22 and a needle tip protective tool 30 . The needle tip protective tool 30 is mounted on the housing 12 with the metal needle 21 inserted into an inner section so that the metal needle 21 can be removed together with the internal needle 20 from the external needle 10 . A main body 31 of the needle tip protective tool 30 has a cylindrical shape. Window sections 34 a, 34 b are provided on opposing circumferential surfaces of the main body 31 . On a rear end marginal section of window section 34 a , a movable gripped section 32 is provided whose outer section 32 b extends toward the outside of the main body 31 and whose end consists of a grip section 32 c . The gripped section 32 c and the grip section 33 c are latchable with each other within main body 31.

1 - 10 . (canceled) 
     
     
         11 . An indwelling needle assembly comprising:
 a cannula including a housing defining an interior space, the interior space having a proximal end with a reduced diameter;   an inner needle having a sharpened distal tip portion and an enlarged diameter adjacent the distal tip portion;   a needle tip protector positioned within the interior space of the housing of the cannula, the needle tip protector being slidably positioned about the inner needle and having a first end and a second end, the second end defining a through-hole, the enlarged diameter of the inner needle being larger than a diameter of the through-hole; and   a first inwardly movable blocking member supported on the needle tip protector;   wherein withdrawing the inner needle in a proximal direction through the through-hole causes the enlarged diameter of the inner needle to engage the needle tip protector adjacent the through-hole to effect withdrawal of the needle tip protector from within the interior space of the housing of the cannula, and wherein withdrawal of the needle tip protector from within the interior space of the housing causes the first blocking member to engage an inner wall adjacent the proximal end of the housing to move the first blocking member inwardly such that the first blocking member blocks the distal tip portion of the inner needle.   
     
     
         12 . The indwelling needle assembly according to  claim 11 , further comprising a second blocking member, wherein withdrawal of the needle tip protector from within the interior space of the housing causes the second blocking member to engage an inner wall adjacent the proximal end of the housing to move the second blocking member inwardly such that the second blocking member blocks the distal tip portion of the inner needle. 
     
     
         13 . The indwelling needle assembly according to  claim 11 , further comprising a second blocking member diametrically opposed to the first blocking member. 
     
     
         14 . The indwelling needle assembly according to  claim 12 , wherein a proximal end of the first blocking member is attached to the needle tip protector and a proximal end of the second blocking member is attached to the needle tip protector. 
     
     
         15 . The indwelling needle assembly according to  claim 14 , wherein each of the first and second blocking members have distal ends formed to lock together when mutually engaged with one another. 
     
     
         16 . The indwelling needle assembly according to  claim 13 , wherein the needle tip protector further comprises a slip ring arranged such that upon withdrawal of the inner needle, the slip ring is caused to slide over the first and second blocking members to move the first and second blocking members inwardly. 
     
     
         17 . The indwelling needle assembly according to  claim 16 , wherein a proximal end of the first blocking member is attached to the needle tip protector and a proximal end of the second blocking member is attached to the needle tip protector. 
     
     
         18 . The indwelling needle assembly according to  claim 17 , wherein each of the first and second blocking members have distal ends formed to lock together when mutually engaged with one another. 
     
     
         19 . The indwelling needle according to  claim 12 , wherein a distal end of the first blocking member is attached to the needle tip protector and a distal end of the second blocking member is attached to the needle tip protector. 
     
     
         20 . The indwelling needle assembly according to  claim 19 , wherein the first and second blocking members have proximal ends forming a tongue and groove interrelation. 
     
     
         21 . The indwelling needle assembly according to  claim 11 , wherein the first end of the needle tip protector defines a through-hole. 
     
     
         22 . The indwelling needle assembly according to  claim 21 , wherein the through-hole defined at the first end of the needle tip protector has a larger diameter than a diameter of the through-hole defined at the second end of the needle tip protector. 
     
     
         23 . The indwelling needle assembly according to  claim 22 , wherein the enlarged diameter of the inner needle is smaller than the diameter of the through-hole at the first end of the needle tip protector and larger than the diameter of the through-hole at the second end of the needle tip protector. 
     
     
         24 . An indwelling needle assembly comprising:
 a cannula including a housing defining an interior space, the interior space having a proximal end with a reduced diameter;   an inner needle having a sharpened distal tip portion and an enlarged diameter adjacent the distal tip portion;   a needle tip protector positioned within the interior space of the housing of the cannula, the needle tip protector being slidably positioned about the inner needle and having a first end and a second end, the second end defining a through-hole, the enlarged diameter of the inner needle being larger than a diameter of the through-hole; and   a first blocking member supported on the needle tip protector, the first blocking member having an open position wherein the distal tip portion of the inner needle is proximally and distally translatable beyond the first blocking member and a closed position wherein the distal tip portion of the inner needle is prevented from distally translating beyond the first blocking member,   wherein during proximal translation of the inner needle engagement of the enlarged diameter of the inner needle with the needle tip protector adjacent the through hole transitions the first blocking member from the open position to the closed position.   
     
     
         25 . The indwelling needle assembly according to  claim 24 , wherein engagement of the enlarged diameter of the inner needle with the needle tip protector adjacent the through hole proximally withdraws the needle tip protector from within the housing of the cannula. 
     
     
         26 . The indwelling needle assembly according to  claim 25 , wherein proximal withdrawal of the needle tip protector from within the housing causes the first blocking member to move inwardly to the closed position.