WO1995006493A1

WO1995006493A1 - Catheter sharp retraction system

Info

Publication number: WO1995006493A1
Application number: PCT/US1994/009840
Authority: WO
Inventors: Victor M. Haughton; Anton H. Clemens
Original assignee: Haughton Victor M; Clemens Anton H
Priority date: 1993-08-31
Filing date: 1994-08-31
Publication date: 1995-03-09
Also published as: US5376075A; EP1208870A3; EP1208870A2; AU678601B2; JPH09504189A; AU7679194A; CA2172502A1; EP0716618A1

Abstract

A trocar and catheter assembly for automatically disarming the trocar after placement of the catheter into a patient's blood vessel includes a spring urging retraction of the trocar and a releasable retainer mechanism for maintaining the trocar in an extended position during insertion of the catheter into the blood vessel. In one embodiment, the catheter is removably mounted to a handle which defines an internal passage. Disengaging the handle from the catheter after placement of the catheter into the blood vessel actuates the releasable retainer mechanism for allowing the trocar to be drawn into the handle passage under the influence of a spring, to enclose the sharpened end of the trocar after use. In another embodiment, the insertion device is in the form of a pair of wings which are movable between a closed position and an open position. The wings are in their closed position and grasped by the user when inserting the catheter into the blood vessel, and are thereafter moved to their open position. Movement of the wings to their open position actuates the releasable retainer mechanism, and the trocar is then drawn rearwardly so that its sharpened end is drawn into the catheter passage under the influence of the spring.

Description

CATHETER SHARP RETRACTION SYSTEM BACKGROUND AND SUMMARY This invention relates to an intravenous cathe¬ ter and trocar system, and more particularly to a system providing automatic retraction of the trocar after inser¬ tion of the catheter into a blood vessel.

Numerous patents disclose syringes which in¬ clude a system for either automatically or semi-automati- cally retracting the syringe needle after use, to prevent accidental contact with the needle. One such syringe is shown in Linde ann, et al. U.S. Patent 4,874,382, issued October 17, 1989. In addition Kuuli U.S. Patent 4,747,831 shows a structure for manually retracting a catheter trocar after the trocar has been used to insert the catheter into a blood vessel of a patient.

It is an object of the present invention to provide an automatic arrangement for retracting a trocar after use of the trocar to insert a catheter into a blood vessel. It is a further object of the invention to incorporate an automatic trocar retraction system into various types of catheters. Yet another object of the invention is to provide a trocar retraction system which is relatively simple in concept and inexpensive to manu¬ facture. In accordance with the invention, an intrave¬ nous catheter system includes a catheter defining an internal passage and a trocar having an exposed sharpened end extending from the catheter passage when in an ex¬ tended position, for use in placing the catheter into a patient's blood vessel. The system further includes an insertion device for manual engagement by a user for use in inserting the sharpened end of the trocar, and thereby the catheter, into the blood vessel. The insertion device includes structure defining an internal passage, and the trocar is releasably engaged with the insertion device when the trocar is in its extended position, to extend outwardly from the internal passage and through the catheter passage. Bias means is interconnected between the insertion device and the trocar, for urging retraction of the trocar from its extended position into the catheter passage. A releasable retainer mechanism functions to retain the trocar in its extended position prior to and during insertion of the catheter and the sharpened end of the trocar into the blood vessel, and for releasing engagement between the trocar and the insertion device in response to manual manipulation of the insertion device by the user after placement of the catheter into the blood vessel. Such manual manipulation of the insertion device functions to actuate the releas¬ able retainer mechanism, to provide retraction of the trocar from its extended position into the catheter passage under the influence of the bias means.

In one form of the invention, the insertion device comprises a handle having one or more side walls defining the internal passage, with the handle being removably engaged with the catheter to provide disengage- ent of the handle from the catheter in response to manual manipulation of the handle after placement of the catheter into the blood vessel. Disengagement of the handle from the insertion device actuates the releasable retainer mechanism, to release engagement between the trocar and the handle and to provide retraction of the trocar from its extended position. The bias means com¬ prises a spring or other biasing means interconnected between the trocar and ^"the handle, to urge withdrawal of the trocar into and through the catheter passage and into the handle passage upon disengagement of the handle from the catheter. The handle passage opens onto an end of the handle, and a plug member is mounted within the handle passage toward the open end of the handle. The plug member defines a passage through which the trocar extends when in its extended position, and the spring is interposed between the trocar and the plug member to draw the trocar through the plug member passage upon disen- gagement of the handle from the catheter. A retraction head is mounted to the inner end of the trocar, and the spring is located between the plug member and the retrac¬ tion head. The catheter includes an enlarged outer end portion defining an open outer end leading to an internal cavity, and an inner tubular end portion defining an open inner end and an internal passage extending between the internal cavity and the open inner end. The handle is removably engaged within the internal cavity defined by the enlarged outer end portion of the catheter. The handle plug member is removably engageable within the internal cavity defined by the enlarged outer end portion of the catheter, and the releasable retainer mechanism is mounted to the plug member and interposed between the trocar and the enlarged outer end portion of the cathe¬ ter. The releasable retainer mechanism functions to re¬ lease engagement between the handle and the trocar upon removal of the plug member from the internal cavity defined by the enlarged outer end portion of the cathe- ter. The trocar retraction head includes a detent dis¬ posed within the plug member passage. The releasable retainer mechanism is engaged with the trocar detent to retain the trocar in its extended position, and is disen¬ gaged from the trocar detent upon removal of the plug member from the internal cavity to provide retraction of the trocar under the influence of the spring. In one form-, the releasable retainer mechanism includes a pair of retainer wings'mounted within a slot formed in. the plug member, and engageable between the catheter and the trocar detent when the plug member is engaged within the internal cavity defined by the enlarged outer end portion of the catheter. Removal of the plug member from the catheter internal cavity releases engagement of the retainer wings between the catheter and the trocar de- tent.

In another form of the invention, the insertion device includes a pair of wings pivotably mounted for movement between a first position in which the wings are positioned substantially together and a second position in which the wings are moved apart. Manual movement of the wings between their first and second positions func- tions to actuate the releasable retainer mechanism, to release engagement between the trocar and the insertion device and to provide retraction of the trocar from its extended position. The insertion device includes a tubular body defining the internal passage within which the trocar is mounted, and the wings are pivotably mount¬ ed to the tubular body. The catheter is mounted to and extends outwardly from the tubular body, and defines an internal passage in communication with the internal passage defined by the body. The bias means, such as a spring, functions to withdraw the sharpened end of the trocar rearwardly into the catheter passage upon release of engagement between the trocar and the insertion device in response to movement of the wings away from their first position. The internal passage defined by the tubular body opens onto the rearward end of the body, and a rearward portion of the trocar extends outwardly from the rearward end of the body. The releasable retainer mechanism includes a hub member mounted to the rearward portion of the trocar, and a detent arrangement inter- posed between the hub member and the wings for retaining the trocar in its extended position when the wings are in their first position, and for releasing engagement be¬ tween the wings and the hub member when the wings, are moved away from their first position toward their second position. The detent arrangement includes a stud mounted to the hub member, and a recess formed in each wing for receiving a portion of the stud when the wings are in their first position, and for releasing engagement be¬ tween the stud and the wings when the wings are moved toward their second position. The tubular body defines an external shoulder, and the spring is interposed be¬ tween the external shoulder and the hub member for urging retraction of the trocar into the catheter passage. The trocar includes a wedge-shaped stop portion disposed within the body passage, for cooperating with wedge structure disposed within the body passage for stopping rearward movement of the trocar under the influence of the bias means when engagement between the trocar and the insertion device is released. A tube may be connected to the rearward portion of the trocar, for communicating blood withdrawn from a patient to a blood collection receptacle.

The invention further contemplates a method of retracting the sharpened end of the trocar after place¬ ment of the catheter into the patient's blood vessel, substantially in accordance with the foregoing summary. Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS The drawings illustrate the best mode presently contemplated of carrying out the invention.

In the drawings:

Fig. 1 is a longitudinal cross-sectional view of a catheter and trocar assembly incorporating a remov¬ able handle for providing automatic retraction of the trocar into the handle after disengagement of the handle from the catheter;

Fig. 2 is an enlarged portional sectional view of the catheter and trocar assembly of Fig. 1, showing the releasable retainer mechanism maintaining the trocar in its extended position;

Fig. 3 is a section view taken along line 3-3 of Fig. 1;

Fig. 4 is an exploded end elevation view of the releasable retainer mechanism plug member and wings of the catheter and trocar system of Fig. 1;

Fig. 5 is longitudinal sectional view of the trocar and catheter assembly of Fig. 1, showing retrac- tion of the trocar into the handle after disengagement of the handle from the catheter;

Fig. 6 is a perspective view showing a butter¬ fly-type catheter and trocar assembly incorporating an automatic trocar retraction system according to the invention, showing the wings moved together and the trocar in its extended position;

Fig. 7 is a view of the catheter and trocar assembly of Fig. 6 showing the wings moved apart and retraction of the trocar;

Fig. 8 is a partial longitudinal sectional view of the catheter and trocar assembly of Figs. 6 and 7, showing the trocar in its extended position;

Fig. 9 is a partial longitudinal sectional view similar to Fig. 8, showing the trocar in its retracted position; and

Fig. 10 is a section view taken along line 10- 10 of Fig. 8.

DETAILED DESCRIPTION OF THE INVENTION Referring to Fig. 1, a retractable catheter assembly 20. generally includes a handle 22, a catheter assembly 24, a trocar 26 terminating in a sharpened outer end 28, and a releasable retainer mechanism 30.

Catheter assembly 24 includes an inner tubular portion 32 defining a passage 33, which terminates in an open inner end from which trocar outer end 28 extends when- trocar 26 is in its Fig. 1 position. Catheter assembly 24 further^" includes an enlarged outer end por¬ tion 34 which defines an open outer end and an internal cavity 36 which communicates between passage 33 defined by inner tubular portion 32 and the open outer end de¬ fined by catheter enlarged outer end portion 34. Cathe¬ ter enlarged outer end portion 34 defines a peripheral inwardly extending lip 38 disposed between the open outer end of enlarged end portion 34 and internal cavity 36 defined thereby. Handle 22 is cylindrical in shape, defining a side wall 40, and end wall 42, and an internal passage 44 which opens onto the inner end of handle 22.

A plug 46 is mounted to handle 22 at its open inner end. Plug 46 is in the form of a pair of identical plug halves, shown in Figs. 2-5 at 46a, 46b. Plug halves 46a, 46b are identical in construction.

Plug halves 46a, 46b each define a rear end including an outwardly extending lip 48a, 48b, respec- tively. Lips 48a, 48b are received within a circumferen¬ tial internal groove formed in the internal surface of handle side wall 40 adjacent its open inner end, for mounting plug 46 to handle 22. The inner surface of handle side wall 40 adjacent the inner end of handle 22 is ramped, as shown at 50, for facilitating push-on insertion of plug halves 46a, 46b into the open inner end of handle 22 and engagement of lips 48a, 48b with the circumferential groove formed in the inner surface of handle side wall 40. Referring to Figs. 1 and 5, plug halves 46a,

46b include peripheral shoulders 52a, 52b, respectively, and nose portions 54a, 54b, respectively, extending outwardly from shoulders 52a, 52b. Nose portions 54a, 54b are shaped similarly to internal cavity 36 defined by catheter enlarged outer end portion 34.

As shown in Figs. 3 and 4, plug halves 46a, 46b further define spacers 56a, 56b, respectively. Spacers 56a, 56b function to space plug halves 46a, 46b apart from each other when plug halves 46a, 46b are mounted to handle 22, to define a slot 58 therebetween.

With plug halves 46a, 46b mounted within the open inner end of handle 22 as described, shoulders 52a, 52b are spaced just outwardly from the inner end of handle 22 with nose portions 54a, 54b extending there- from. Catheter 24 is engaged with plug halves 46a, 46b as shown in Figs. 1 and 2, with catheter lip 38 being placed over shoulders 52a, 52b for retaining catheter 24 in place. Nose portions 54a, 54b of plug halves 46a, 46b, respectively are received within internal cavity 36 defined by catheter enlarged outer end portion 34.

Referring to Fig. 2, trocar 26 is mounted to a retraction head, shown generally at 60. Retraction head 60 is located within handle passage 44, and includes a flange 62 in close proximity to the inner surface defined by handle side wall 40. Flange 62 extends outwardly from a main body portion 64. A circumferential groove 66 is formed in flange 62 adjacent body portion 64.

Body portion 64 further defines a forward extension 68 through which trocar 26 extends. A circum¬ ferential spherical detent 70 is formed at the forward end of extension 68. As shown in Figs. 1 and 2, plug halves 46a, 46b includes bosses 72a, 72b extending rearwardly from rear surfaces 74a, 74b, respectively. A spring 76 is inter¬ posed between retraction head 60 and plug 46. The for¬ ward end of spring 76 is engaged with rear surfaces 74a, 74b of plug halves 46a, 46b, respectively, with bosses

72a, 72b received within spring 76. The rearward end of spring 76 is received within groove 66 formed in flange 62 of retraction head 60.

A pair of retainer wings, shown at 78, 80 (Figs. 2-5) are received within slot 58 between plug halves 46a, 46b. Wings 78, 80 define outer surfaces 82, 84,. -respectively, and facing inner surfaces 86, 88, respectively. Retaining recesses 90, 92 are formed in facing surfaces 86, 88, respectively. When wings 78,80 are in their position as shown in Figs. 1-3, detent 70 is received within retaining recess 90, 92. Wings 78, 80 are trapped between trocar 26 and the inner wall of catheter enlarged outer end portion 34, to thereby main¬ tain trocar 26 in its extended position against the rearward bias exerted by spring 76.

In operation, catheter and trocar assembly 20 functions as follows. Initially, trocar 26 is in its armed condition, as shown in Figs. 1 and 2 wherein trocar sharpened end 28 protrudes outwardly from the end of catheter inner tubular portion 32. With catheter and trocar assembly 20 in this condition, the user grasps handle 22 and enlarged outer end portion 34 of catheter 24 to place inner tubular portion 32 of catheter 24 into a patient's blood vessel. Sharpened outer end 28 of trocar 26 pierces the patient's skin for allowing inner tubular portion 32 of catheter 24 to penetrate the skin. during placement of catheter 24, trocar 26 is maintained in its extended position as shown in Figs. 1 and 2 against the force of spring 76, by retainer wings 78, 80 remaining in their Fig. 2 position, as previously de¬ scribed. After inner tubular portion 32 of catheter 24 is in place in the patient's blood vessel, the user grasps handle 22 and catheter enlarged outer end portion 34 to remove handle 22 from catheter 24 with a pull-apart motion. Plug shoulders 52a, 52b are disengaged from catheter lip 38, to allow plug member nose portions 54a, 54b to be withdrawn from internal cavity 36 defined by catheter enlarged outer end portion 34. Upon such disen¬ gagement of plug 46 from catheter 24, retainer wings 78, 80 are no longer trapped between trocar 26 and the inner wall of catheter enlarged outer end portion 34, and thereby release retention of detent 70. Spring 76 then extends to its position as shown in Fig. 5, to withdraw retraction head 60 into handle passage 44, and thereby withdrawal of trocar 26^" through catheter passage 33 and through internal cavity 36 defined by catheter enlarged outer end portion 34. Trocar 26 also passes rearwardly through slot 58 between plug member halves 46a, 46b, and is thereafter completely enclosed within handle passage 44 to prevent accidental contact with trocar sharpened end 28. Handle 22 with trocar 26 contained therein is then discarded, and a typical fitting is engaged with catheter enlarged outer end portion 34 for withdrawing blood from the patient or for providing intravenous introduction of a fluid into the patient's blood vessel.

Fig. 2 illustrates another embodiment of the invention, in the form of a butterfly trocar and catheter assembly 100. Assembly 100 includes a tubular body 102 which defines a forwardly extending catheter portion 104. A pair of wings 106, 108 are pivotably mounted to body 102. Referring to Figs. 6-8, a ring 110 is mounted to wing 106, and a ring 112 is mounted to wing 108. Ring 110 passes through a slot 114 formed in wing 108, and in a like manner ring 112 passes through a slot (not shown) formed in wing 106. Rings 110, 112 are mounted within grooves 116, 118 formed in the outer surface of body 102, for pivotably mounting wings 106, 108 to body 102. Referring to Figs. 8 and 9, catheter portion

104 defines an internal passage 120 which opens onto the forward end of catheter portion 104. Passage 120 opens rearwardly into an internal passage 122 formed in body 102, which includes wedge structure 124 at its rearward end. A rear passage 126 is formed in body 102, extending rearwardly from wedge structure 124 and opening onto the rearward end of body 102. A circumferential external shoulder 128 is formed on body 102.

A trocar, shown generally at 130, is mounted to body 102. Trocar 130 defines a sharpened outer end 132, which extends outwardly from the end of catheter portion 104 " hen trocar and catheter assembly 100 is in its armed condition as shown in Figs. 6 and 8. Trocar 130 includes a boss 134 provided with a wedge surface 136. Trocar 130 further includes a longitudinal internal passage 138

(Fig. 9) which extends between and opens onto sharpened outer end 132 and the rear end of trocar 130, shown at 140.

A hub 142 is mounted to trocar 130 adjacent its rear end 140. Hub 142 is provided with a circumferential groove 144 surrounding trocar 130. Hub 142 further includes an upstanding stud 146 (Figs. 7, 9 , and 10). A spring 148 is received within groove 144 of hub 142, and is seated at is opposite end against shoulder 128 defined by body 102. Spring 148 functions to urge trocar 130 inwardly away from its extended position. Referring to 7, 9 and 10, a pair of slots, 150,

152 are formed in wings 106, 108, respectively. Slots 150, 152 receive stud 146 therewithin when wings 106, 108 are in their closed position, as shown in Fig. 6.

In operation, the embodiment of Figs. 6-10 functions as follows. Prior to placement of catheter portion 104 and trocar sharpened end 132 into a patient's blood vessel, wings 106, 108 are in their closed position of Fig. 6. In this position, trocar 130 is maintained in its Fig. 8 position, with sharpened end 132 extending outwardly from the forward end of catheter portion 104, by stud 146 being received within slots 150, 152 formed in wings 106, 108, respectively as shown in Fig. 10. This maintains trocar 130 in its Fig. 8 position against the rearward biasing force applied by spring 148 to trocar 130. The user then grasps wings 106, 108 in their closed position of Fig. 2, and places catheter portion 104 into a patient's blood vessel, with trocar sharpened end 132 piercing the patient's skin to facilitate entry of catheter portion 104 into the blood vessel. Wings 106, 108 are then moved to their open position of Fig. 7 against the surface of the patient's skin. Typically, a piece of tape is then applied over wings 106, 108 to maintain catheter^'portion i04 in place within the. blood vessel. Upon unfolding wings 106, 108 from their Fig. 6 position and moving wings 106, 108 toward their Fig. 7 position, stud 146 is disengaged from slots 150, 152 in wings 106, 108, respectively. This releases engagement between the insertion device and trocar 130, and trocar 130 is then forced to its Fig. 9 position under the influence of spring 148 until engagement of trocar wedge surface 136 with wedge structure 124 at the rearward end of passage 122. Such movement of trocar 130 results in trocar sharpened end 132 being drawn into passage 120 defined by catheter portion 104. Fluid communication is established with the patient's blood vessel through trocar passage 138 and passage 120 defined by catheter portion 104. Withdrawal of trocar sharpened end 132 into catheter portion passage 120 prevents accidental contact with trocar sharpened end 132 after withdrawal of cathe¬ ter portion 104 from the patient. A tube 154 is connected to the rearward end of trocar 130, and a receptacle 156 is mounted to the oppo¬ site end of tube 154. In this manner, blood can be withdrawn from the patient by connecting a blood collec¬ tion device to receptacle 156. Alternatively, fluid can be introduced into the patient's blood vessel by connect¬ ing an IV set to receptacle 156.

Various alternatives and embodiments are con¬ templated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.

Claims

CLAIMS We claim:

1. In an intravenous catheter system including a catheter defining an internal passage and a trocar having an exposed sharpened end extending from the cathe¬ ter passage when in an extended position, for use in placing the catheter into a blood vessel of a patient, the improvement comprising: an insertion device for manual engagement by a user for use in inserting the sharpened end of the trocar into the patient's blood vessel to establish communica- tion therewith by the catheter, the insertion device including structure defining an internal passage, wherein the trocar is releasably engaged with the insertion device when in its extended position so as to extend outwardly from the internal passage and through the catheter passage; bias means interconnected between the insertion device and the trocar for urging retraction of the trocar from its extended position into the catheter passage; and a releasable retainer mechanism for retaining the trocar in its extended position prior to and during insertion of the catheter and the trocar sharpened end into the blood vessel, and for releasing engagement between the trocar and the insertion device in response to manual manipulation of the insertion device by the user- after placement of the catheter into the blood vessel, to provide retraction of the trocar from its extended position into the catheter passage under the influence of the bias means.

2. The improvement of claim 1, wherein the insertion device comprises a handle having one or more side walls defining the internal passage, wherein the handle is removably engaged with the catheter to provide disengagement of the handle from the catheter in response to manual manipulation of the handle after placement of the catheter into the blood vessel, and wherein disen- gagement of the handle from the insertion device func¬ tions to actuate the releasable retainer mechanism to release engagement between the trocar and the handle and to provide retraction of the trocar from its extended position.

3. The improvement of claim 2, wherein the bias means comprises a spring interconnected between the trocar and the handle so as to urge withdrawal of the trocar into and through the catheter passage and into the handle passage upon disengagement of the handle from the catheter.

4. The improvement of claim 3, wherein the handle defines first and second ends, and wherein the handle passage opens onto the first end of the handle, and wherein the handle further includes a plug member mounted within the handle passage at the first end of the handle, the plug member defining a passage through which the trocar extends when in its extended position, and wherein the spring is interposed between the trocar and the plug member to draw the trocar through the plug member passage and into the handle passage upon disen¬ gagement of the handle from the catheter.

5. The improvement of claim 4, wherein the trocar is mounted to a retraction head disposed within the handle passage, and wherein the spring is interposed between the plug member and the retraction head for urging the trocar into the handle passage.

6. The^* improvement of claim 2, wherein the catheter includes an enlarged outer end portion defining an open outer end leading to an internal cavity, and an inner tubular end portion defining an open inner end and an internal passage extending between the internal cavity and the open inner end, and wherein the handle is remov¬ ably engaged within the internal cavity defined by the enlarged outer end portion of the catheter.

7. The improvement of claim 6, wherein the handle defines first and second ends, and wherein the handle passage opens onto the first end of the handle, and wherein the handle further includes a plug member mounted at the first end of the handle and extending therefrom, wherein the plug member is removably engage¬ able within the internal cavity defined by the enlarged outer end portion of the catheter, and wherein the re¬ leasable retainer mechanism is mounted to the plug member and interposed between the trocar and the enlarged outer end portion of the catheter, and functions to release engagement between the handle and the trocar upon removal of the plug member from the internal cavity defined by the enlarged outer end portion of the catheter.

8. The improvement of claim 7, wherein the trocar extends through a passage formed in the plug member and includes a detent disposed within the plug member passage, and wherein the releasable retainer mechanism is engaged with the trocar detent when the plug member is engaged within the internal cavity defined by the enlarged outer end portion of the catheter to retain the trocar in its extended position, and wherein the releasable retainer mechanism is disengaged from the trocar detent upon removable of the plug member from the internal cavity to provide retraction of the trocar from its extended position under the influence of the bias means.

9. The improvement of claim 8, wherein the plug member passage comprises a slot, and wherein the releasable retainer" mechanism comprises a pair of. re¬ tainer wings mounted within the slot and engageable be- tween the catheter and the trocar detent when the plug member is engaged within the internal cavity defined by the enlarged outer end portion of the catheter, and wherein removal of the plug member from the internal cavity functions to release engagement of the retainer wings between the catheter and the trocar detent.

10. The improvement of claim 1, wherein the insertion device comprises a pair of wings pivotably mounted for movement between a first position in which the wings are positioned substantially together and a second position in which the wings are moved apart, wherein manual movement of the wings between the first and second positions functions to actuate the releasable retainer mechanism to release engagement between the trocar and the insertion device to provide retraction of the trocar from its extended position.

11. The improvement of claim 10, wherein the insertion device further comprises a tubular body to which the wings are pivotably mounted, wherein the tubu¬ lar body defines the internal passage within which the trocar is mounted, and wherein the catheter is mounted to and extends outwardly from the tubular body, the catheter defining an internal passage in communication with the internal passage defined by the body, and wherein the bias means functions to withdraw the sharpened end of the trocar rearwardly into the catheter passage upon release of engagement between the trocar and the insertion de¬ vice.

12. The improvement of claim 11, wherein the tubular body defines a first end and a second end, where¬ in the catheter extends from the first end of the body and wherein the internal passage defined by the body opens onto the second end of the body, and wherein a rearward portion of the trocar extends from the body internal passage outwardly from the second end of the body.

13. The improvement of claim 12, wherein the releasable retainer mechanism comprises a hub member mounted to the rearward portion of the trocar and a detent arrangement interposed between the hub member and the wings for retaining the trocar in its extended posi¬ tion when the wings are in their first position, and for releasing engagement between the wings and the hub member when the wings are moved away from their first position toward their second position.

14. The improvement of claim 13, wherein the detent arrangement comprises a stud mounted to the hub member, and a recess formed in each wing for receiving a portion of the stud when the wings are in their first position, and for releasing engagement between the stud and the wings when the wings are moved away from their first position toward their second position.

15. The improvement of claim 13, wherein the tubular body defines an external shoulder, and wherein the bias means comprises a spring interposed between the external shoulder and the hub.

16. The improvement of claim 12, wherein the trocar includes a stop portion disposed within the body passage for cooperating with the structure of the body adjacent the body passage to stop rearward movement of the trocar under the influence of the bias means when engagement between the trocar and the insertion device is released.

17. The improvement of claim 16, wherein the trocar stop portion comprises wedge structure disposed within the body passage, wherein the body passage in¬ cludes a rear wedge surface engaged by the wedge struc- ture of the trocar upon rearward movement of the trocar, to stop rearward movement of the trocar.

18. The improvement of claim 12, further comprising a blood collection receptacle and a tube extending between the blood collection receptacle and the rearward portion of^" the trocar for communicating blood from the trocar to the blood collection receptacle.

19. In an intravenous catheter system includ¬ ing a catheter defining an internal passage and a trocar having an exposed sharpened end and extending from the catheter passage when in an extended position, for use in placing the catheter into a blood vessel of a patient, a method of retracting the sharpened end of the trocar after placement of the catheter into the blood vessel, comprising the steps of: providing an insertion device including struc- ture defining an internal passage; releasably engaging the trocar with the inser¬ tion device when the trocar is in its extended position so that the trocar extends outwardly from the internal passage and through the catheter passage; urging retraction of the trocar from its ex¬ tended position into the catheter passage; inserting the sharpened end of the trocar into the blood vessel to establish communication therewith via the catheter, by manual operation of the insertion de- vice; and manually manipulating the insertion device after placement of the catheter into the blood vessel, to release engagement between the trocar and the insertion device, wherein the trocar is retracted from its extended position into the catheter passage.