referring to fig1 - 4 , safety catheter assembly 10 consists of an elongated housing 12 made up of two parts 12a and 12b parted along line 14 ( as seen in fig4 ), and having a slot 16 along the face of part 12a . if desired , housing 12 may be constructed as a single member . visible in fig1 - 4 are pushers 18 and 22 , and needle catch 24 to be further described . in fig2 needle 26 sheathed in and having its tip extending out of catheter 28 , extends out of housing 12 and is ready to be inserted into the arm 32 of the patient . in fig3 and 4 needle 26 has been retracted into housing 12 leaving catheter 28 in place with its tip in the arm 32 of the patient . housing 12 is moved transversely as shown by the arrows in fig3 permitting catheter 28 to pass out of slotted opening 34 in housing 12 . for the details of construction of assembly 10 , reference is made to fig5 a , 6 , and 7 . it will be seen that housing part 12b is provided with one half of a main central passageway 36 of semi circular cross section and a one half of secondary passageway 38 also of semi circular cross section parallel to and adjacent passageway 36 . the two passageways are joined by a slot 42 for a purpose to be later described . housing part 12b is provided with matching passageways and slot so that when the two parts 12a and 12b are assembled as in fig1 - 4 , there are two passageways circular in cross section with a slot joining them . within main passageway 36 for slideable movement is a plunger 44 . the latter consists of a cylindrical barrel 46 with a pair of circular grooves 47 and 48 , a passageway 49 connecting needle 26 to a port 26a , and end portions 52 and 54 of reduced diameters the latter of which is to accomodate catheter 28 shown in fig6 . extending from end portion 54 of plunger 44 is hollow needle 26 . as seen in fig5 catheter 28 ( shown in phantom for illustrative purposes ) encloses needle 26 with the adaptor 56 portion of catheter 28 fitting over end portion 54 of plunger 44 , and the tip of needle 26 exposed from the end of the body 58 of catheter 28 . a floating cylindrical ring 62 rides over end portion 52 of plunger 44 thus filling the space between the right end of catheter 28 and the left end of cylindrical barrel 46 when the catheter and the plunger are assembled within housing 12 as illustrated in fig5 and 6 . ring 62 and barrel 46 are provided with push rods 22 and 18 , respectively , previously identified , extending out of slot 16 in housing part 12a as shown in fig1 , and 3 . the left end of housing 12 is provided with a slotted opening 64 which communicates with slotted side opening 34 previously identified . this communication of the two slotted openings 34 and 64 renders corner 66 of housing 12 open to permit catheter 28 to slide out of housing 12 as illustrated in fig3 and 4 . mounted within secondary passageway 38 is a spring 68 attached to the left end of passageway 38 . extending into passageway 38 through the slotted opening 42 between the two passageways 36 and 38 is a compression pin 72 . when plunger 44 is pushed to the left using push rod 18 as will be explained later , pin 72 will compress spring 68 thereby resulting in plunger 44 being biased to the right . housing 12 is also provided with the needle catch 24 which consists of a member 73 pivoted at a pin 74 in a slot 76 also seen in fig4 large enough to accomodate member 73 as is illustrated . at one end , member 73 is provided with a claw 77 extending into passageway 36 through slot 76 while at the other end a spring 78 is provided to bias claw 77 into passageway 36 . claw 77 has a sloped side 82 on the right side and a surface 84 on the left side which is substantially vertical to the axis of plunger 44 . also provided in housing 12 is a safety catch pin 86 ( see fig3 and 4 ) located in housing portion 12a aligned with groove 48 with plunger 44 in its position shown in fig5 and normally in the retracted position shown . catch pin 86 consists of a barrel 88 and a mushroom shaped cap 92 . as will be seen below , after assembly 10 has been used and catheter 28 has been removed , and needle 26 retracted into housing 12 , catch 86 would be depressed so that the bottom tip of barrel 88 would enter groove 48 and prevent needle 26 from accidentally being extended out of housing 12 . catch pin 86 is designed so that once it is depressed it can no longer be accidentally retracted . this is accomplished by the use of the mushroom shaped cap which does not provide an edge along the surface of housing 12 which can be caught , or it can be slightly countersunk to prevent accidental retraction of the catch . any other suitable design may be employed if it is desired to make the device tamper proof . in the operation of the apparatus just described , the combined catheter and needle assembly 10 is delivered ready for use as shown in fig1 and 5 , with needle 26 retracted and catheter 28 covering needle 26 with the tip exposed . the medical professional holds assembly 10 in one hand , and with the other hand slides pusher 18 to the left , moving needle 26 and catheter 28 to become exposed as shown in fig2 compression pin 72 compressing spring 68 . the left end of plunger 44 contacting the sloped side 82 of claw 77 raises the latter which drops into groove 47 thereby locking plunger 44 along with needle 26 and catheter 28 in the extended position shown in fig2 . it will be noted that floating ring 62 with its pusher 22 extending out of slot 16 will be moved along with plunger 44 and will end up in the position shown also in fig2 . the worker then gently inserts needle 26 into the patient , in this case , for illustrative purposes , arm 32 . the presence of a drop of blood coming out of the distal end of needle 26 through port 26a confirms that the needle had entered a blood vessel . the professional then slides the tip of the catheter 28 into the opening of the blood vessel by moving pusher 22 to the left , so that floating ring 62 moves catheter 28 . the professional will then hold catheter 28 in place using a thumb or other finger to press catheter 28 against the skin of the patient , and depress member 73 against spring 76 , raising claw 77 out of groove 47 thereby releasing plunger 44 which will be pushed back into housing 12 by spring 68 , leaving catheter 28 in the position shown in fig4 . then , unit 10 is gently moved transversely as shown in fig3 letting catheter 28 pass through opening 34 and remaining on the arm of the patient . the professional will then adjust catheter into the position desired and tape it down against the arm of the patient . catheter 28 may then be capped for later use , or the iv can be attached in conventional fashion to adaptor 56 on catheter 28 . safety pin 88 would then be depressed to enter groove 48 thereby insuring that needle 26 will not be accidentally exposed , and the whole remaining assembly , minus catheter 28 , will be deposited in a repository for such used medical equipment for proper disposal . instead of employing pusher 18 extending out of slot 16 , the arrangement shown in fig8 may be employed to move plunger 44 to the left . as seen in fig8 assembly 10 &# 39 ; otherwise identical to assembly 10 previously described , is provided with a plunger 44 &# 39 ; identical to plunger 44 except that pusher 18 is removed and the distal end of plunger 44 &# 39 ; is extended to pass out of housing 12 &# 39 ; so that the rear end 44a &# 39 ; can be pushed by a finger , for example , to move plunger 44 &# 39 ; toward the proximate end of housing 12 &# 39 ;. it is thus seen that there has been provided a unique combination of a needle and catheter in a compact assembly which is convenient to use , is disposable , and at the same time sheaths the needle after use so that there is no risk of accidental puncture afterwards . while only certain preferred embodiments of the invention has been described it is understood that many variations are possible without departing from the principles of this invention as defined in the claims which follow .
a combined needle and catheter assembly comprising a body in which is provided a plunger having the needle at one end with the catheter enclosing said needle with the tip exposed . a pusher is provided to move the plunger to the proximate end of the body to expose the needle with catheter and to lock the plunger in place against a spring which biases the plunger toward the distal position in the body . after use of the needle with the catheter moved into place , a release is employed to permit the plunger with needle to be driven back into the body , permitting the catheter to be separated from the body and ready for use .