Intravenous catheter inserting device

An intravenous catheter inserting device comprising:

• a catheter hub including
• a surrounding tip wall which surrounds a first axis, and which confines a through hole extending along the first axis,
• a sleeve wall which is opposite to said surrounding tip wall along the first axis, and which has an inner sleeve wall surface that surrounds the first axis, and that confines an insert hole larger than said through hole, and
• an intermediate tubular wall which is interposed between said surrounding tip wall and said sleeve wall, which confines a duct communicating said insert hole with said through hole, and which has a communicating port extending therethrough to communicate said duct with ambient air;
• a tubular catheter including a proximate segment which is disposed in said through hole and which extends along the first axis to communicate with said duct, and a distal segment which extends from said proximate segment along the first axis to project outwardly of said surrounding tip wall;
• a barrel having outer and inner surrounding barrel wall surfaces opposite to each other and surrounding a second axis, said inner surrounding barrel wall surface confining a passage having open forward and rearward ends that are disposed opposite to each other in a longitudinal direction parallel to the second axis, said inner surrounding barrel wall surface including a larger-diameter segment and a smaller-diameter segment that confine rear and front passageways, respectively, and that are disposed proximate to said open rearward and forward ends, respectively, to form a surrounding shoulder portion between said larger-diameter segment and said smaller-diameter segment, said outer surrounding barrel wall surface having a front surrounding region which is proximate to said open forward end, and which is secured relative to said inner sleeve wall surface, thereby resulting in coincidence of the first axis with the second axis;
• a needle cannula including tip and fixed ends opposite to each other, and a middle segment interposed between said tip and fixed ends;
• a tubular needle seat received in said passage and extending along the second axis, said tubular needle seat including
• a hub end disposed to secure said fixed end,
• a surrounding engaged wall which extends from said hub end along the second axis, and which confines an axial path to accommodate or communicate with said fixed end, said surrounding engaged wall having an outer engaged wall surface which surrounds the second axis, and which engages and which is rotatable relative to said smaller-diameter segment about the second axis between interengaged and released positions, where said surrounding engaged wall is unmovable and movable relative to said smaller-diameter segment along the second axis, respectively, and
• an anchoring segment which confines an axial through hole to communicate with said passage, and which extends outwardly of said front passageway from said surrounding engaged wall, said anchoring segment terminating at an anchoring end which is rotated with said surrounding engaged wall to move from a hook-up position that is closer to said surrounding shoulder portion, to a depressed position that is remote from said surrounding shoulder portion when said surrounding engaged wall is turned in a clockwise direction from the interengaged position to the released position;
• and
• a plunger received in said passage such that in a use position, said plunger is movable along said larger-diameter segment in the longitudinal direction, and such that in a disposal position, said plunger is unmovable along but is rotatable relative to the larger-diameter segment, said plunger including
• a plunger body which includes a top end wall disposed to confront said surrounding shoulder portion, and a bottom end wall opposite to said top end wall in the longitudinal direction, said bottom end wall extending outwardly of said open rearward end to permit movement and rotation of said plunger, said top end wall having an inner peripheral edge portion which surrounds the second axis, and which defines a cavity therein, said cavity extending along the second axis and towards said bottom end wall and containing fluid at a reduced pressure, and
• a seal member including
• an anchored portion disposed to be engageable with said anchoring end such that when said plunger is in the disposal position and when said surrounding engaged wall is in the interengaged position, rotation of said plunger body in the clockwise direction relative to said larger-diameter segment brings said surrounding engaged wall to turn from the interengaged position to the released position, thereby moving said anchoring end from the hook-up position to the depressed position, and
• a sealing portion which is sealingly attached to said inner peripheral edge portion along a sealing line so as to trap said fluid in said cavity, the sealing line being configured such that movement of said anchoring end from the hook-up position to the depressed position results in depression of said anchored portion so as to rip the sealing line, thereby releasing said seal member from said plunger body, so that said tubular needle seat together with said needle cannula will be pulled by said seal member which is suctioned into said cavity due to a pressure difference between the reduced pressure and the ambient air that is introduced through said communicating port, thereby permitting retraction of said needle cannula from said tubular catheter into said cavity.