AU2007229352B1 - Intravenous catheter introducing device - Google Patents

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicant(s): MING-JENG SHUE, PHILLIP SHUE and DEBORAH HUANG Invention Title: Intravenous catheter introducing device The following statement is a full description of this invention, including the best method for performing it known to me/us: 2 introducing device 9 is specifically not suitable for patients whose blood pressure is not sufficient to permit flow of blood therethrough, such as an emergency case, aged people, and pediatrics patients, and patients whose target vein is barely visible due to abundant adipose tissue, such as women and obese patients, since the health care worker will have difficulty determining whether the catheter 93 has been successfully introduced into the target vein, and may need to locate the vein by moving the needle cannula 94 in the skin of the patient, thereby complicating and prolonging the cannulation procedure and causing great discomfort to the patient. Furthermore, although conventional self-retracting IV catheter introducers permit self-retraction of the used needle cannula into the syringe barrel after introduction of the catheter is completed, the blood in the barrel may be forced out of the barrel during the retraction of the used needle cannula so that blood contamination may occur. According to this invention, the intravenous catheter introducing device includes: a needle cannula which has a front segment terminating at a tip end, and a rear connecting end opposite to the front segment along the axis in a longitudinal direction; a tubular needle seat which includes a front hub portion that extends along the axis to terminate at a front end, and that is disposed to fix the rear connecting end therein, a gripped portion that extends from the front hub portion 3 away from the front end, and a rear plug portion that extends from the gripped portion and distal from the front hub portion, and that has an internal duct extending through the gripped portion to be communicated with the rear connecting end; a barrel which has an inner surrounding barrel surface defining a passage therein, the passage having rearward and forward openings, the inner surrounding barrel surface including a larger-diameter portion and a smaller-diameter portion which are disposed proximate to the rearward and forward openings, respectively, the larger-diameter portion having a retaining area which is spaced apart from the smaller-diameter portion in the longitudinal direction; a tubular grip member which, in a position of use, is disposed to hold, with a holding force, the gripped portion in a position of immovability along the axis relative to the retaining area; a tubular plunger which is disposed to be movable in the 4 passage along the larger-diameter portion, the plunger having a front opened end wall which is movable to abut against the grip member so as to place the tubular plunger in a pre-disposal position, a rear end wall which is disposed 5 opposite to the front opened end wall, and which extends outwardly of the rearward opening so as to be manually operable, and an intermediate surrounding wall which is interposed between the front opened end wall and the rear end wall, and which defines an accommodation compartment; 10 a tubular receptacle which has a socket end, an air-permeable end, and a tubular wall segment interposed therebetween to confine a flashback chamber, wherein when the tubular gripmemberis in the positionof use, the tubular receptacle is retained in the accommodation compartment by 15 a first friction force, with the socket end and the air-permeable end respectively confronting the rear plug portion and the rear end wall to establish air communication between the internal duct and the flashback chamber, such that when the tubular plunger is in the pre-disposal position, 20 the socket end is engaged with the rear plug portion, such that when the grip member is pushed forward by virtue of a forward movement of the front opened end wall against the holding force, the gripped portion is released from the grip member so as to permit axial movement of the gripped portion 25 relative to the retainingarea, and such that when the gripped portion is released from the gripmember, a continued forward movement of the front opened end wall against the first 5 friction force will result in movement of the tubular needle seat together with the tubular receptacle, through the engagement of the rear plug portion with the socket end, towards the rear end wall by virtue of a biasing force so 5 as to place the tubular needle seat and the needle cannula ina disposal position, where the tip end of the needle cannula is retracted into the passage, and where the socket end is closer to the rear end wall than in the position of use; a biasing member disposed to provide the biasing force; 10 a catheter hub which defines therein a duct that permits extension of the front segment of the needle cannula therethrough; and a tubular catheter having a proximate segment which is inserted into the duct, and a distal segment which extends 15 from the proximate segment and which surrounds and sheathes the front segment of the needle cannula while permitting the tip end to project forwardly of the distal segment for piercing a patient's skin. Preferably, an air-permeable member which is made from 20 aporousmaterialisintegrally formedwith the air-permeable end so as to prevent blood from trickling out of the flashback chamber. Preferably, the tubular plunger has an outlet which permits air communication between the accommodation 25 compartment and the ambient air, and which is disposed downstream of the air permeable end. Other features and advantages of the present invention 6 will become apparent in the following detailed description of thepreferredembodiments of the invention, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a conventional IV catheter 5 introducing device; Fig. 2 is an exploded sectional view of a first preferred embodiment of an intravenous catheter introducing device according to this invention; Fig. 3 is a sectional view of the first preferred 10 embodiment in a ready-to-use position; Fig. 4 is a fragmentary sectional view of a portion of the first preferred embodiment; Fig. 5 is a sectional view of the first preferred embodiment in a position of use; 15 Fig. 6 is a sectional view of the first preferred embodiment in a pre-disposal position; Fig. 7 is a sectional view of the first preferred embodiment during an operation of retracting a needle cannula; 20 Fig. 8 is a sectional view of the first preferred embodiment in a retracted position; Fig. 9 is a sectional view of the first preferred embodiment showing two outlets in a closed position; Fig. 10 is a sectional view of the second preferred 25 embodiment of an intravenous catheter introducing device according to this invention; Fig. 11 is a sectional view of the second preferred 7 embodiment in a retracted position; Fig. 12 is a sectional view of the third preferred embodiment of an intravenous catheter introducing device according to this invention; 5 Fig. 13 is a sectional view of the third preferred embodiment in a retracted position; and Figs. 14 to 18 respectively are sectional view of the fourth to eighth preferred embodiments of an intravenous catheter introducing device according to this invention. 10 Before the present invention is described in greater detail, it should be noted that same reference numerals have been used to denote like elements throughout the specification. Referring to Figs. 2 to 4, the first preferred embodiment 15 of an intravenous catheter introducing device according to the present invention is shown to comprise a barrel 1, a needle cannula 23, a tubular needle seat 22, a tubular grip member 21, a tubular plunger 3, a tubular receptacle 34, a biasing member 4, a catheter hub 24, a tubular catheter 20 25, and a tip protector 26. The barrel 1 has a surrounding wall 13 surrounding an axis. The surrounding walll3 has aninner surrounding barrel surface 130 which defines a passage 11 therein. The passage 11 has rearward and forward openings 131,132 which are 25 opposite to each other in a longitudinal direction along the axis. The inner surrounding barrel surface 130 includes a larger-diameter portion133 and a smaller-diameter portion 8 134 which are disposed proximate to the rearward and forward openings 131,132, respectively, and a shoulder 135 which is interposed therebetween. The larger-diameter portion 133 has a projecting retaining area 137 which is spaced apart 5 from the smaller-diameter portion 134 in the longitudinal direction. The smaller-diameter portion 134 includes an entry region 15, a transit region 17 which extends from the entry region 15 forwardly, and an inner annular abutment surface 16 which confronts rearwardly. The barrel 1 further 10 has a finger flange 138 disposed proximate to the rearward opening 131. The needle cannula 23 has a front segment 231 terminating at a tip end 232, and a rear connecting end 233 opposite to the front segment 231 along the axis. 15 The tubular needle seat 22 includes a front hub portion 220 which extends along the axis to terminate at a front end 225 to be surrounded by the entry region 15, and which is disposed to fix the rear connecting end 233 of the needle cannula 23 therein, a gripped portion 222 which extends from 20 the front hub portion 220 away from the front end 225, and a rear plug portion 223 which extends from the gripped portion 222 and distal from the front hub portion 220 and which has an internal duct 224 extending through the gripped portion 222 along the axis to be communicated with the rear connecting 25 end 233 of the needle cannula 23. The front hub portion 220 has a shoulder surface 221 which is disposed rearwardly of the front end 225, and which is spaced apart from the inner 9 annular abutment surface 16 by the transit region 17. The tubular grip member 21 is retained at the retaining area 137 of the barrel 1 in a position of use so as to hold the gripped portion 222 of the needle seat 22 in a position 5 of immovability along the axis relative to the retaining area 137 by virtue of a holding force. To be specific, the tubular grip member 21 is disposed in retaining engagement with the projecting retaining area 137 of the larger-diameter portion 133, and in gripping engagement with the gripped [0 portion 2 2 2 of the needle seat 22 by second and third friction forces, respectively, which cooperate in radial directions to serve as the holding force. The tubular plunger 3 is disposed to be movable in the passage llalong the larger-diameterportion130. The plunger L5 3 has a front opened end wall 321, a rear end wall 322 which is opposite to the front opened end wall 321 and which extends outwardly of the rearward opening 131 so as to be manually operable, and an intermediate surrounding wall 32 which is interposed between the front opened end wall 321 and the 20 rear end wall 322 and which defines an accommodation compartment 31. The intermediate surrounding wall 32 has a plurality of ribs 324 which are formed on an outer surface thereof and adjacent to the rear end wall 322. The tubular plunger 3 has two outlets 33 which communicate 25 the accommodation compartment 31 with the ambient air, and which are disposed downstream of the air permeable end 344. In this embodiment, the outlets 33 are formed in the 10 intermediate surrounding wall 32 adjacent to the rear end wall 322 to facilitate closing by a user's finger when the user grips and moves the tubular plunger 3. The tubular plunger 3 further has a deformable sealing 5 member 36 which is configured to surround the front opened end wall 321, and which is in air-tight sliding engagement with the larger-diameter portion 130. The tubular receptacle 34 has a socket end 343 and an air-permeable end 344 spaced apart from each other in the 10 longitudinal direction, and a tubular wall segment 340 interposed therebetween to confine a flashback chamber 342. In the position of use, the tubular receptacle 34 is retained in the accommodation compartment 31 by a first friction force generated between protrusion and recess portions 341,323 15 such that the socket end 343 and the air-permeable end 344 respectively confront the rear plug portion 223 and the rear end wall 322 to establish an air communication between the internal duct 224 and the flashback chamber 342. An air-permeable member 35 is integrally formed with the 20 air-permeable end 344, and is made from a porous material. The rear end wall 322 of the tubular plunger 3 defines an access opening for insertion of the tubular receptacle 34 into the accommodation compartment 31 therethrough. An end cap 37 is detachably mounted to the rear end wall 322 25 to close the access opening. The barrel 1 has a forward end wall 139 which defines the forward opening 132. The biasing member 4 is in the form l1 of a coil spring 4 which surrounds the front segment 231 of the needle cannula 23, and which is compressed between the forward end wall 139 and the shoulder surface 221 of the needle seat 22 to provide a biasing force to move the 5 needle seat 22 rearwardly. The catheter hub 24 is detachably sleeved on the surrounding wall 13 of the barrel 1, and defines therein a duct 241 that permits extension of the front segment 231 of the needle cannula 23 therethrough. 10 The tubular catheter 25 has a proximate segment 251 which is inserted into the duct 241, and a distal segment 252 which extends from the proximate segment 251 and which surrounds and sheathes the front segment 231 of the needle cannula 23 while permitting the tip end 232 to project forwardly 15 of the distal segment 252 for piercing a patient's skin. The tip protector 26 is removably sleeved on the surrounding wall 13 for shielding the needle cannula 23. In the position of use, the front hub portion 220 of the needle seat 22 is retained at the retaining area 137 by the 20 holding force (i.e., the second and third friction forces), and the inner annular abutment surface 16 is spaced apart from the shoulder surface 221 by the transit region 17. Referring to Figs. 3, 4 and 5, in an IVintroducing stroke, the tip protector 26 is removed first to expose the tip end 25 232 of the needle cannula 23. The operator grips the surrounding wall 13 of the barrel 1 and pierces the patient's vein with the tip end 232 so as to introduce the tubular 1 2 catheter 25 into the vein. The blood flowing into the passage 11 is visible from the surrounding wall 13 so that the operator can check whether the needle cannula 23 has been inserted properly into the vein. The operator can then separate the 5 catheter hub 24 from the barrel 1, and the IV introducing operation is completed. Referring to Figs. 5 and 6, since the passage 11 is in air communication with the accommodation compartment 31 via the flashback chamber 342 so as to be communicated with the 10 ambient air through the outlets 33, after the IV introducing stroke, theoperatorcanpress the tubularplunger4 forwardly so as to move the deformable sealing member 36 to abut against the grip member 21 to thereby place the tubular plunger 3 in a pre-disposal position. At this time, the blood in the 15 passage 11 can flow into the flashback chamber 342 due to air communication of the passage 11 with the ambient air, and the air-permeable member 35 can prevent the blood from trickling out of the flashback chamber 342. Thus, the blood will not be forced out of the barrel 1 during forward pressing 20 of the tubular plunger 3. Subsequently, the socket end 343 is engaged with the rear plug portion 223. When the grip member 21 is pushed forward by virtue of a forward movement of the tubular plunger 3 against the holding force, the grip member 21 is moved to 25 disengage from the retaining region 137 so that the second friction force disappears, and the shoulder surface 221 of the needle seat 22 is moved to pass from the entry region 1 3 15 to the transit region 17 to abut against the inner annular abutment surface 16. Then, by virtue of the abutment of the shoulder surface 221 against the inner annular abutment surface 16, the gripped portion 222 is released from the 5 grip member 21 so that the third friction force disappears. The time lag between the releasing of the second and third friction forces can result in a smooth operation of the tubular plunger 3. At the same time, by virtue of a counteracting effect of the forward end wall 139 of the barrel LO 1 and the coil spring 4, the protrusion portion 341 of the receptacle 34 is moved to disengage from the recess portion 323 in the plunger 3 so as to permit releasing of the coil spring 4. Therefore, as shown in Fig. 7, through the engagement L5 oftherearplugportion223withthe socketend343, arearward movement of the needle seat 22 will, by virtue of the biasing force of the coil spring 4, force the tubular receptacle 34 to move towards the rear end wall 322 to place the tubular needle seat 22 and the needle cannula 23 ina disposal position, 20 as shown in Fig. 8, where the tipend 232 of the needle cannula 23 is retracted into the passage 11, and where the socket end 343 is closer to the rear end wall 322 than in the position of use. It is noted that when the tubular plunger 3 is pressed 25 to place the tubular needle seat 22 and the needle cannula 23 in the disposal position, the tubularplunger 3is retained at the larger-diameter portion 133 through snug engagement 1 4 between an annular recess 136 and an annular projection 325 so as to prevent rearward pulling of the tubular plunger 3 for reuse. Moreover, the forward pressing of the tubular plunger 3 can be limited by the ribs 324 that abut against 5 the barrel 1 at the rearward opening 131 so as to prevent excess forward movement of the tubular plunger 3, which may cause the grip member 21 to deform and interfere with the rearward movement of the needle seat 22. Referring to Fig. 9, during the IVintroducing operation, 10 if blood is not observed in the passage 11, the operator can hold the tubular plunger 3 and close the outlets 33 with his/her thumb and index finger to interrupt air communication between the passage land the ambient air. Then the operation can pull the tubular plunger 3 rearwardly so as to generate L5 a reduced pressure in the passage 11 to thereby facilitate flow of blood into the passage 11. Thus, the operator can easily check whether the tubular catheter 25 has been successfully introduced into a target vein of the patient. Referring to Figs. 10 and 11, the second preferred 20 embodiment of an intravenous catheter introducing device according to this invention is shown to be similar to the first preferred embodiment in construction. The difference resides in that the tubular wall segment 340 of the tubular receptacle 34 has an outer annular abutment surface 345 25 adjacent to the air-permeable end 344. The biasing member 4 is in the form of a coil spring 4 which surrounds the tubular wall segment 340 and which is compressed between the front 15 opened end wall 321 and the outer annular abutment surface 345. Moreover, the outer annular abutment surface 345 is retained at the recess portion 323 of the tubular plunger 3 to generate the first friction force. 5 Referring to Figs. 12 and 13, the third preferred embodiment of an intravenous catheter introducing device according to this invention is shown to be similar to the first preferred embodiment in construction. The difference resides in that the biasing member 4 is in the form of a 10 coil spring 4 which is received in the accommodation compartment 31 of the tubular plunger 3 and which has a secured end 43 that is secured to the intermediate surrounding wall 32 adjacent to the rear end wall 322, and a tensed end 44 that is secured to the tubular wall segment 340 of the tubular 15 receptacle 34 so as to remain tensed in the position of use. Referring to Fig. 14, the fourth preferred embodiment of an intravenous catheter introducing device according to this invention is shown to be similar to the third preferred embodiment in construction. The difference resides in that 20 the biasing member 4 has a secured end 43 which is secured to the end cap 37. Referring to Fig. 15, the fifth preferred embodiment of an intravenous catheter introducing device according to this invention is shown to be similar to the third preferred 25 embodiment in construction. The difference resides in that the outlet 33 is formed in the end cap 37 to facilitate closing of the outlet 33 by the operator.

16 Referring to Fig. 16, the sixth preferred embodiment of an intravenous catheter introducing device according to this invention is shown to be similar to the second preferred embodiment in construction. The difference resides in that 5 the outlet 33 is formed in the end cap 37, and a cover plate 38 is disposed on the tubular plunger 3, and is movable relative to the tubular plunger 3 between closing and opening positions, where the cover plate 38 engages with and disengages from the end cap 37 to close and open the outlet 10 33, respectively. Referring to Fig. 17, the seventh preferred embodiment of an intravenous catheter introducing device according to this invention is shown to be similar to the second preferred embodiment in construction. The difference resides in that 15 the outlet 33 is formed in the rear end wall 322 of the tubular plunger 3, and the intermediate surrounding wall 32 of the tubular plunger 3 has an annular barrier 327 formed adjacent to the rear end wall 322 such that the air-permeable end 344 of the tubular receptacle 34 is stopped by the annular 20 barrier 327 when the tubular receptacle 34 is moved to the disposal position. Referring to Fig. 18, the eighth preferred embodiment of an intravenous catheter introducing device according to this invention is shown to be similar to the first preferred 25 embodiment in construction. The difference resides in that the outlet 33 is formed in the rear end wall 322 of the tubular plunger 3, and the intermediate surrounding wall 32 of the 1 7 tubular plunger 3 has an annular barrier 327 formed adjacent to the rear end wall 322 such that the air-permeable end 344 of the tubular receptacle 34 is stopped by the annular barrier 327 when the tubular receptacle 34 is moved to the 5 disposal position. In addition, a cover plate 38 is disposed on the tubular plunger 3 and is movable relative to the tubular plunger 3 between closing and opening positions, where the cover plate 38 engages and disengages from the rear end wall 322 to close and open the outlet 33, respectively. 10 As illustrated, according to the intravenous catheter introducingdevice of this invention, the usedneedlecannula 23 can be retracted into the passage 11 of the barrel 1 to thereby avoid occurrence of an accidental needle stick. Further, during the forward pressing of the tubular plunger 15 3 to retract the needle cannula 23, since the passage 11 is air communicated with the ambient air, the blood in the passage 11 may flow into the flashback chamber 342, and the air-permeable member 35 can prevent the blood from trickling out of the flashback chamber 342. Thus, the blood will not 20 be forced out of the barrel 1. Moreover, during the IV introducing operation, once blood is not observed in the passage 11, the operator can close the outlet (s) 33 and pull the tubular plunger 3 rearwardly to generate a reduced pressure in the passage 11 to thereby facilitate flow of 25 blood into the passage 11. Thus, the operator can easily check whether the tubular catheter 25 has been successfully introduced into a target vein of the patient.

17A In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary 5 implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. 10 It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

Claims (19)

1. An intravenous catheter introducing device comprising: a needle cannula having a front segment terminating at a tip end, and a rear connecting end opposite to said 5 front segment along the axis in a longitudinal direction; a tubular needle seat which includes a front hub portion that extends along the axis to terminate at a front end, and that is disposed to fix said rear connecting end therein, a gripped portion that extends from said front hub portion 10 away from said front end, and a rear plug portion that extends from said gripped portion and distal from said front hub portion, and that has an internal duct extending through said gripped portion along the axis to be communicated with said rear connecting end; 15 a barrel having an inner surrounding barrel surface which surrounds the axis, and which defines a passage therein, said passage having rearward and forward openings which are opposite to each other in the longitudinal direction, saidinnersurroundingbarrel surface including 20 a larger-diameter portion and a smaller-diameter portion which are disposed proximate to said rearward and forward openings, respectively, said larger-diameter portion having a retaining area which is spaced apart from said smaller-diameter portion in the longitudinal direction; 25 a tubular grip member which, in a position of use, is disposed tohold, withaholding force, saidgrippedportion in a position of immovability along the axis relative to 19 said retaining area; a tubular plunger which is disposed to be movable in said passage along said larger-diameter portion, said plunger having a front opened end wall which is movable 5 to abut against said grip member so as to place said tubular plunger in a pre-disposal position, a rear end wall which is disposed opposite to said front opened end wall, and which extends outwardly of said rearward opening so as to be manually operable, and an intermediate surrounding 10 wall which is interposed between said front opened end wall and said rear end wall, and which defines an accommodation compartment; a tubular receptacle which has a socket end and an air-permeable end spaced apart from each other in the L5 longitudinal direction, and a tubular wall segment interposed between said socket end and said air-permeable end to confine a flashback chamber, wherein, when said tubular grip member is in the position of use, said tubular receptacle is retained in said accommodation compartment 20 by a first friction force, with said socket end and said air-permeable end respectively confronting said rear plug portion and said rear end wall to establish air communicationbetween said internal duct and said flashback chamber, 25 such that when said tubular plunger is in the pre-disposalposition, said socket endis engaged with said rear plug portion, 20 such that when said grip member is pushed forward by virtue of a forward movement of said front opened end wall against the holding force, said gripped portion is released from said grip member to permit 5 axial movement of said gripped portion relative to said retaining area, and such that when said gripped portion is released from said grip member, a continued forward movement of said front opened end wall against the first friction 10 force will result in movement of said needle seat together with said tubular receptacle, through the engagement of said rear plug portion with said socket end, towards said rear end wall by virtue of a biasing force so as to place said needle seat and said needle 15 cannula in a disposal position, where said tip end of said needle cannula is retracted into said passage, and where said socket end is closer to said rear end wall than in the position of use; and a biasing member disposed to provide said biasing force. 20

2. The intravenous catheter introducing device of Claim 1, wherein said smaller-diameter portion includes an entry region which is configured to surround said front hub portion, and a transit region which extends from said entry region towards said forward opening, said tubular 25 grip member being disposed to be in retaining engagement with said retaining area of said larger-diameter portion, and in gripping engagement with said gripped portion of 21 said needle seat by second and third friction forces, respectively, which cooperate in radial directions to serve as theholding force, such that once anaxialmovement of said gripped portion commences relative to said 5 retaining area by virtue of the forward movement of said grip member and said front opened end wall, said front hub portion is moved to pass from said entry region to said transit region so as to permit said tubular grip member to be disengaged from said retaining area before 10 disengagement of said gripped portion from said tubular grip member in the pre-disposal position.

3. The intravenous catheter introducing device of Claim 2, wherein said front hub portion of said needle seat has a shoulder surface which is disposed rearwardly of said 15 front end, and which faces towards said forward opening, said smaller-diameter portion further including an inner annular abutment surface which is spaced apart from said shoulder surface by said transit region such that byvirtue of abutment of said shoulder surface against said inner 20 annular abutment surface, forward movement of said grip member and said front opened end wall results in release of said gripped portion from said grip member against the third friction force.

4. The intravenous catheter introducing device of Claim 3, 25 wherein said barrel has a forward end wall which defines said forward opening, said biasing member being in the form of a coil spring which surrounds said front segment 22 of said needle cannula, and which is compressed between said forward end wall and said shoulder surface of said needle seat.

5. The intravenous catheter introducing device of Claim 1, 5 wherein said tubular wall segment of said tubular receptacle has an outer annular abutment surface adjacent to said air-permeable end, said biasing member being in the form of a coil spring which surrounds said tubular wall segment and which is compressed between said front 10 opened end wall and said outer annular abutment surface.

6. The intravenous catheter introducing device of Claim 1, wherein said biasing member is in the form of a coil spring which is received in said accommodation compartment and which has a secured end that is secured to said intermediate 15 surrounding wall adjacent to said rear end wall, and a tensed end that is secured to said tubular wall segment of said tubular receptacle so as to remain tensed in the position of use.

7. The intravenous catheter introducing device of Claim 1, 20 wherein said rear end wallof said tubular plunger defines an accessopening forinsertion ofsaid tubular receptacle into said accommodation compartment, said device further comprising an end cap which is detachably mounted to said rear end wall to close said access opening, said biasing 25 member being in the form of a coil spring which is received in said accommodation compartment and which has a secured end that is secured to said end cap, and a tensed end 2 3 that is secured to said tubular wall segment of said tubular receptacle so as to remain tensed in the position of use.

8. The intravenous catheter introducing device of Claim 1, further comprising an air-permeable member which is made 5 from a porous material, and which is integrally formed with said air-permeable end so as to prevent blood from trickling out of said flashback chamber.

9. The intravenous catheter introducing device of Claim 1, wherein said tubular plunger has a deformable sealing 10 member which is configured to surround said front opened end wall, and which is in air-tight sliding engagement with said larger-diameter portion.

10. The intravenous catheter introducing device of Claim 1, wherein said tubular plunger has an outlet that 15 communicates said accommodation compartment with the ambient air, and that is disposed downstream of said air permeable end.

11. The intravenous catheter introducing device of Claim 10, wherein said outlet is formed in said intermediate 20 surrounding wall adjacent to said rear end wall to facilitate closing by a user's finger when the user grips and moves said tubular plunger.

12. The intravenous catheter introducing device of Claim 10, wherein said rear end wall of said tubular plunger defines 25 an access opening forinsertion ofsaid tubular receptacle into said accommodation compartment, said device further comprising an end cap which is detachably mounted to said 24 rear end wall to close said access opening, said outlet being formed in said end cap.

13. The intravenous catheter introducing device of Claim 10, wherein said outlet is formed in said rear end wall of 5 said tubular plunger.

14. The intravenous catheter introducing device of Claim 13, further comprising a cover plate which is disposed on said tubular plunger and which is movable relative to said tubularplungerbetween closingandopeningpositions, 10 where said cover plate engages and disengages from said rear end wall to close and open said outlet, respectively.

15. The intravenous catheter introducing device of Claim 13, wherein said intermediate surroundingwall of saidtubular plunger has an annular barrier formed adjacent to said 15 rear end wall such that said air-permeable end of said tubular receptacle is stopped by said annular barrier when said tubular receptacle is moved to the disposal position.

16.The intravenous catheter introducing device of Claim 1, 20 further comprising: a catheter hubwhich defines thereina duct that permits extension of said front segment of said needle cannula therethrough; and a tubular catheter having a proximate segment which 25 is inserted into said duct, and a distal segment which extends from said proximate segment and which surrounds and sheathes said front segment of said needle cannula 2 5 while permitting said tip end to project forwardly of said distal segment for piercing a patient's skin.

17. The intravenous catheter introducing device of Claim 1, wherein said tubular plunger and said larger-diameter 5 portion respectively have an annular projection and an annular recess which are configured such that once said tubular plunger is placed in the pre-disposal position, said annular projection and said annular recess are snugly engaged with each other so as to prevent rearward pulling 10 of said tubular plunger for reuse.

18.The intravenous catheter introducing device of Claim 1, wherein said intermediate surroundingwallof said tubular plunger has a plurality of ribs which are formed on an outer surface thereof and adjacent to said rear end wall 15 and which are disposed to abut against said barrel at said rearward opening when said tubular plunger is in the disposal position.

19. An intravenous catheter introducingdevice substantially as hereinbefore described with reference to and as 20 illustrated in Figs. 3 to 18.