Power injector and method providing removal of used disposable syringe

A power injector is provided for injecting fluid from a replaceable syringe and through an injection tube into the body of an animal. The syringe includes one or more operator-removable and interchangeable syringe mounting heads, at least one of which mounts syringes of a rear loadable type. Preferably an alternative head is provided that accepts front loadable syringes. The mounting head includes an opening and a moveable syringe holder that preferably pivots open to receive a syringe from the back of the holder and pivots closed to orient the rear of the syringe over the ram. The holder has a slot therethrough having a width sufficient to permit an injection tube attached to the syringe nozzle to be moved transversely through the slot to permit the syringe to be removed from the holder without disconnecting the tube from the orifice of the syringe and without withdrawing the tip of the tube rearwardly through the opening. The holder preferably includes a replaceable insert configured to snugly support a rear loadable syringe of a given configuration. One insert is preferably provided in the form of a pressure sleeve configured to support a syringe during high pressure use. The head has a locking mechanism that locks the syringe to the injector, couples the syringe plunger to the ram, locks and releases the head and locks the holder in operating position.

This invention relates to power injectors, particularly those of the breach 
loading type, and more particularly to the provision for the removal of 
spent replacement syringes and associated tubing from such injectors. 
BACKGROUND OF THE INVENTION 
Power injectors are devices used to inject fluids at controlled and 
programmed rates or pressures into patients. Important uses include 
computed tomography (CT) and angiography, where radiopaque contrast medium 
is injected into a patient's vascular system to enhance diagnostic images. 
With power injectors, a motor-driven ram advances the plunger of a syringe 
under microprocessor control to provide control of injection parameters 
such as flow rate, volume and timing. Such injectors are often loaded with 
sterile empty syringes that are filled by drawing fluid from a supply into 
the syringe through the syringe nozzle by using the ram to draw the 
syringe plunger backward. In other situations, the injectors are loaded 
with prefilled syringes. In either case, the syringes used are typically 
disposed of after a single use. 
In CT and angiography, a typical fluid delivery system includes a power 
injector loaded with a single use disposable syringe that is filled with 
the contrast medium or other fluid, and with a delivery tube connecting 
the nozzle of the syringe to the vascular system of the patient. The 
tubing, which is also typically single-use and disposable, is commonly 
connected to the syringe after the syringe is loaded into the injector. 
When the use of the syringe and tubing is completed, the spent syringe and 
the tubing are removed from the injector and disposed of. Spent syringes 
as well as the used tubing has the capability of dripping or leaking 
residual amounts of fluid. This dripping or leaking can fall upon the 
injector components, particularly the syringe holding structure and 
locking mechanism, where, if not cleaned, can cause contamination or 
interfere with the injector operation. Cleaning of the injector of spilled 
fluid is time consuming, detracts from the utilization of the equipment 
and is accordingly costly. 
In the prior art, many injectors have been configured to support syringes 
that are loaded into holder structure on the injector from the rear. Such 
syringes are typically provided with rear end flanges by which the 
syringes are locked to the holder and held in position for the injector 
ram to be coupled to and drive the syringe plunger. The loading and 
unloading of such rear loading syringes has required the insertion and 
withdrawal of the syringe nozzle through a circular opening in a closed 
annular holder. Upon loading, when no tubing is connected to the syringe 
nozzle, inserting the nozzle through the opening from the rear presents 
little problem. However, removal of a spent syringe from such an injector 
has resulted either in the withdrawal of an entire length of tubing 
through the opening, possibly with its leading end open to drip fluid that 
remains in the tube on the injector parts, or in the need to disconnect 
the tubing from the syringe nozzle and the withdrawal of the open nozzle 
end through the opening, which also can drip fluid onto the injector 
parts. Capping the syringe or the tubing end and the wiping of excess 
drippage undesirably increases the handling involved and is an 
inconvenience. The act of disconnecting the tubing from the syringe also 
occupies the hands of an operator and can result in the release of 
residual fluid that can require a further clean-up task. 
Inventors of the subject matter of the present application have previously 
solved the above problem for certain types of syringes by providing a 
front loading injector. A front loading injector is one in which a front 
loadable syringe is positioned in front of an opening in an injector 
holder and loaded into the holder by translating the syringe rearwardly, 
back end first, into the injector. With front loadable injectors, the 
nozzle of the syringe need not pass through the opening of the holder upon 
loading or unloading. Such an injector, which is described and illustrated 
in U.S. Pat. No. 5,279,569, which is assigned to the assignee of the 
present application, enables an operator to remove the syringe from the 
injector by translating it forwardly away from the injector, without 
removing connected injection tubing from the syringe nozzle. This 
configuration has resulted in the maintenance of the injector free from 
fluid contamination, and has provided easier injector usage, while saving 
operator and physician time. 
However, not all syringes, and particularly not all prefilled syringes, can 
be easily made available in forms that can be loaded into injectors from 
the front. As a result, breach loading or rear loading injector holders 
are still provided for many applications. Rear loading injectors are 
injectors in which a rear loadable syringe is positioned behind a holder 
of the injector and translated, nozzle first through an opening in the 
holder until structure on the syringe, usually a flange or other outwardly 
extending element at the syringe rear, seats forwardly against the holder. 
Usually the holder opens for loading or unloading of a syringe by pivoting 
away from the injector housing, either in hinged or turret fashion. Such 
breach loading injectors still present the above described problems in 
connection with the removing of spent syringes and the connected tubing. 
Breach loading injectors have existed in the prior art that are modified 
versions of the injector disclosed in U.S. Pat. No. 5,279,569, referred to 
above, with the syringe holding head structure replaced with a breach 
loading syringe holder that pivots out of the path of the ram so that a 
rear loading syringe can be loaded or unloaded from the rear of the 
holder. Such injectors have nonetheless possessed the same disadvantages 
in removing spent syringe and injection tubing assemblies possessed by 
other breach loading injectors of the prior art. 
Accordingly, there remains a need for improvement in the removal of spent 
syringe and injection tubing assemblies from power injectors and to 
eliminate the handling and equipment contamination problems that have been 
characteristic of the prior art rear loading power injectors available for 
angiographic and computed tomography. 
SUMMARY OF THE INVENTION 
It is a primary objective of the present invention to facilitate the 
removal of spent disposable syringe and of syringe and tubing combinations 
from power injectors. It is a particular objective of the present 
invention to improve the handling of spent disposable rear-loadable 
syringes and the injection tubing used therewith in power injectors and to 
reduce the likelihood of spillage or leakage of residual injection fluid 
when removing syringes and injection tubing from breach loading power 
injectors. It is a particular objective of the present invention to 
provide for the leak-free and easy handling and removal of used disposable 
rear loadable syringes without the need to disconnect the tubing from the 
syringe and without the need to pull the full length of the tubing through 
the syringe holder. 
According to the principles of the present invention, a syringe holder 
having a syringe receiving opening or cavity therein is provided with a 
slotted rim through which injection tubing can be laterally passed in an 
outward direction when removing a syringe and tubing assembly from the 
syringe holder of a breach loading power injector. The invention is 
particularly applicable to rear loading or breach loading injectors where 
rear loadable syringes are loaded and unloaded from the rear of a holder 
having an opening therein. In loading, the nozzle of the syringe is 
located behind the holder and is the first part of the syringe to enter 
the opening as the syringe is translated axially forward into the opening 
until seating against the holder. Preferably, substantially the entire 
length of the syringe passes into the opening until the syringe seats 
against the holder, preferably by the contact of a flange or other 
extending structure at the rear of the syringe engaging the rear of the 
holder from the back. In unloading, the syringe is translated axially 
rearwardly until the body thereof is behind the holder and out of the 
opening, preferably with the nozzle thereof fully outside of the opening 
and rearward of the holder. 
According to the preferred embodiment of the present invention, a syringe 
holder is pivotally attached to the front of a power injector. The holder 
pivots between an operating position and a loading position, preferably 
about an axis that is tangent to the circumference of the holder. In its 
operating position a syringe held in the holder is aligned with a power 
driven ram of the injector such that the ram can contact and couple to the 
plunger of the syringe through an opening at the back of the syringe. In 
the loading position, a syringe can be inserted into an opening or cavity 
in the holder from the back of the holder so that structure on the 
syringe, such as a supporting, aligning and retaining flange on the rear 
thereof or other structure at the syringe front end, can be engaged by 
structure on the syringe, for example on the holder, to lock and orient 
the syringe on the injector. The holder has a slot on one side of the 
opening or cavity that extends along the entire axial length of the 
holder, which permits the transverse passage of an intermediate section or 
length injection tubing therethrough so that the syringe can be loaded 
into the opening and removed from the opening of the holder while the rear 
end of the injection tubing remains connected to the nozzle of the syringe 
and the front end of the injection tubing may still be connected to fluid 
delivery devices, remains in the vicinity of the patient or is otherwise 
prevented from being withdrawn rearwardly through the opening of the 
holder. 
In the preferred embodiment of the invention, the holder is removable, 
replaceable or exchangeable with holders of other configurations that are 
provided for supporting syringes of differing shapes or types. The holder 
may include an insert or sleeve that forms a replaceable inner lining to 
the rim of the holder and has a cooperating portion of the slot extending 
therethrough. Preferably, however, the holder is formed of integral or 
non-removeable parts the entirety of which are exchangeable to accommodate 
different syringes. Alternative holders include simple support rings that 
are configured to receive flanges and other rear end structure on syringes 
of differing types, while others may be in the form of or include pressure 
restraining jackets having slots extending the lengths thereof to 
similarly allow the injection tubing to be passed to facilitate the 
unloading of the syringe from the injector. 
In further preferred embodiments of the invention, the holder is connected 
to a one of several alternative removable syringe support heads that may 
be interchangeable with heads to support other rear loadable syringes or 
syringes of the front loading type. The holder is preferably permanently 
connected to a head and replaceable therewith. The head may include coding 
structure such as configurations of one or more magnets that are read by 
sensors such as hall effect devices on the injector to provide information 
of the size and shape of the syringe to the controls of the injector. The 
use of two magnets, one with possible two values and the other with three 
possible values, yielding six discrete combinations, is preferred. 
With the present invention, breach loadable syringes, particularly 
prefilled syringes having various configurations of flanges at the rear 
ends thereof, may be loaded into and removed from the power injectors 
while the injection tubing remains connected. In the removal of such 
syringes particularly, leakage and dripping of fluid onto injector 
components is avoided. Syringes can be removed from the injectors without 
the need to disconnect the injection tube from the syringe and without the 
need to pull the tip of the tube rearwardly through the holder opening. 
These and other objectives of the present invention will be readily 
apparent from the following detailed description of the present invention 
in which:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 illustrates the front end of a power head or injection module 
portion of a power injector 10 of a type, for example, that is used for 
angiographic and CT injection. One such injector is described and 
illustrated in U.S. Pat. No. 5,279,569, which is assigned to the assignee 
of the present invention, and is expressly incorporated herein by 
reference herein. The injector 10 includes a injection module housing 11 
that contains a power driven ram 12. The ram 12 is longitudinally moveable 
by activation of a motor (not shown), contained in the housing 11, so that 
free end 13 of the ram 12 is extendable from a retracted position inside 
the housing 11, as illustrated in FIG. 1, to an extended position away 
from the housing 11, as more fully explained in the incorporated patent. 
The injector of U.S. Pat. No. 5,279,569 is described in that patent as 
having a door assembly that constitutes a syringe mounting head of a front 
loading type, that is, of a type in which a syringe can be loaded by 
translating it rearwardly, back end first, into the front of the mounting 
head. 
The embodiment of the invention illustrated in FIG. 1 of this application 
is, however, equipped with a syringe mounting head 15 that is an 
alternative to the front loadable head described in the patent. The 
mounting head 15 is rather of the breach loading or rear loading type. The 
head 15 includes a mounting head base 16, which is pivotally connected to 
the front of the housing 11 to pivot, as illustrated by the arcuate arrow 
18, about a longitudinal shaft 17 to pivot between a closed position, in 
which the head base 16 is illustrated in FIG. 1, and an open position 
illustrated by the phantom line 16a of FIG. 2. In its open position 16a, 
the head base 16 can be translated longitudinally between the open 
position 16a and a removed position which is represented by the phantom 
lines 16b, for removal and replacement of the head 15, as illustrated by 
the arrow 19. 
As further illustrated in FIG. 1, the head 15 is provided with a locking 
mechanism 25 which has several functions including the function of locking 
and unlocking of the head 15 to and from the housing 11 as well as 
additional functions described more fully below. The mechanism 25 is 
provided with an operating lever 26, illustrated in an unlocked or load 
position, which is the position which allows the head 16 to be opened, 
removed and replaced, as was described in connection with FIG. 2 above, 
and which allows syringes to be loaded and unloaded from the mounting head 
15. The lever 26 is moveable to a locked position 26a, represented by 
phantom lines in FIG. 1, which is the position at which the ram 12 is 
operable to drive the plunger of a syringe mounted in the head 15. 
Movement of the lever 26 from its unlocked position to its locked position 
26acauses the head 16 to pivot downward into engagement with a latch 27, 
securely locking the head 16 in its closed position. To perform the 
locking motion of the head 15, the locking mechanism 25 may employ any 
suitable structure, but preferably has that structure illustrated and 
described in detail in U.S. Pat. No. 5,279,569 referred to above. 
The head base 16 has a generally circular opening 30 therethrough when the 
lever 26 is in the load or unlocked position and the locking mechanism 25 
is unlocked. With the lever 26 in this unlocked position, the center of 
the opening 30 is slightly to the side of, and out of alignment with, the 
centerline of the ram 12, as illustrated in FIG. 3. When the head 15 is in 
its closed position and the locking mechanism 25 is locked, the opening 30 
is centered on and in alignment with the ram 12, as illustrated in FIG. 
3A. Pivotally mounted to the base 16 of the head 15 on a shaft 33 adjacent 
the opening 30 is an annular syringe holder 32,32a. The holder 32,32a is 
pivotally mounted to move to an operating position in which the holder 
32,32a is centered in the opening 30, as illustrated in FIGS. 3 and 3A. 
Movement of the lever 26 to its locked position locks the holder 32,32a in 
this operating position within the opening 30. When the lever 26 is in its 
unlocked position, the holder 32,32a is free to pivot on the shaft 33 
between its operating position to its loading position, which is that 
illustrated in FIGS. 1 and 1A. 
The holder 32,32a includes a syringe adapter sleeve 35 or 35a which is 
preferably an integral or permanent part thereof, but may also be one of a 
plurality of interchangeable adapter sleeves which fit snugly within the 
interior of the holder 32,32a. The adapter sleeves 35,35a are preferably 
are each differently configured to accept and securely support a syringe 
of one of several shapes in a syringe receiving opening 39,39a in the 
center of the holder 32,32a. Syringes of the types supported by the 
illustrated holders 32 and 32a are rear loading syringes, such as syringes 
40 and 40a that are respectively illustrated in FIGS. 1 and 1A. The 
syringes 40,40a each include a tubular body 41,41 a that is generally 
cylindrical, a generally frusto-conical front wall 42 terminating in an 
elongated neck 43 having a discharge orifice 44 therethrough and locking 
structure generally in the form of an outwardly extending flange, such as 
the double winged flange 45 of the syringe 40 or the octagonal flange 45a 
of the syringe 40a. The body 41,41a, front wall 42, neck 43 and flange 
45,45a are typically integrally molded from a plastic material which is 
usually transparent or translucent. Adapter sleeve 35 of the embodiment of 
FIG. 1 is configured to receive the double winged flange 45 of the syringe 
40 and to secure it against rotation in the sleeve 35, while the sleeve 
35a of the embodiment of FIG. 1A is configured to receive the hexagonally 
shaped flange 45a of the syringe 40a and to secure it against rotation in 
the sleeve 35a. 
The syringe 40,40a has an open rearward end 47 which provides access by the 
ram 12 to a syringe plunger 48, usually formed of a hard rubber material 
that forms a slidable seal with the inside of the body 41,41a. The plunger 
48 has a coupling element on the back thereof, for example in the form of 
a button 49, which the ram 12 is configured to engage to push or pull the 
plunger 48 forward or pull it backward in the syringe body 41,41a. Forward 
motion of the plunger 48 in the body 41,41a expels fluid at a programmed 
and controlled rate from the orifice 44 into a tube 50 connected to the 
neck 43 of the syringe 40,40a. The holder 32,32a as well as the sleeves 
35,35a are provided with a radial slot 54,54a, respectively, extending 
therethrough and having a width that is greater than the outside diameter 
of the tube 50. The slot 54,54a permits the tube 50 to be translated 
sideways through the slot 54,54a, thereby permitting a syringe 40,40a 
having a tube 50 connected to the tip of the neck 43 to be removed from 
the holder 32,32a without disconnecting the tube 50 from the neck 43 and 
without pulling the tube 50 entirely through the opening 39,39a in the 
center of the holder 32,32a. 
The holder 32 having the adapter sleeve 35 of FIG. 1 is useful for CT and 
other applications that involve only moderate pressures that are typically 
in the range of 30 to 150 psi. For angiographic and other high pressure 
applications, where pressures may be in the 500 to 2000 psi range, for 
example, the holder 32ais preferred having an adapter sleeve which is in 
the form of pressure jacket or sleeve 35a. With a pressure jacket sleeve 
35a, the holder 32a has a tubular wall 61 that terminates in a conical 
front wall that conforms to the outside of the body 41 a and front wall 42 
of the syringe 40a, with a hole 62 in the front thereof to permit 
extension of the syringe neck 43 therethrough. With the holder 32a that 
has the jacket 35a, the slot 54a extends the length thereof from the 
opening 39a in the back thereof to the hole 62. The existence of the slot 
54a in the pressure jacketed holder 32a creates a reduction in the 
pressure resisting strength of the jacket 35a, which is offset by 
provision for extra reinforcing material, such as one or more integral 
rings 64 in jacket 35a. The slot 54a also extends through these rings 64. 
A syringe 40,40a is loaded into the holder 32,32a with the holder 32,32a, 
the base 16 and the lever 26 in their respective loading and unlocked 
positions (FIGS. 1, 1A). The syringe 40,40a is inserted, front end first, 
through the opening 39,39a in the holder 32,32a from the back side 
thereof, until the flange 45,45a thereof is properly seated against the 
back side of the sleeve 35,35a. Then the holder 32,32a is pivoted into its 
operating position on the head 16, which is in its unlocked position (FIG. 
3). The moving of the lever 26 to its locked position causes the locking 
mechanism 25 to lock the base 16 to the housing 11, as discussed above, 
and to lock the holder 32,32a in its operating position, also as discussed 
above, which locks the syringe flange 45,45a to the holder 32,32a. In 
addition, the locking of the locking mechanism 25, which causes the 
pivoting of the base 16 from its unlocked position to its locked position 
(FIG. 3 to FIG. 3A), also thereby causes the coupling 49 on the syringe 
plunger 48 to translate laterally into alignment with the ram 12. If the 
plunger coupling 49 is in the plane of the end of the ram 12 (which is the 
position of the ram 12 illustrated in FIG. 1A, where the ram 12 is 
slightly extended from the housing 11), this translation causes the 
plunger 48 to couple to the ram 12 as the plunger coupling 49 and ram 12 
move into mutual engagement by the relative transverse motion. If the ram 
12 is not in alignment with the plunger coupling 49 when the lever 26 is 
moved, the ram 12 can thereafter engage the coupling 49 by moving 
forwardly to snap into engagement with relative axial movement of the 
coupling 48 toward the ram 12. After the syringe 40,40a is so locked in 
the holder 32,32a, the rear end of the tubing 50 is typically connected to 
the tip of the neck 43 of the syringe 40,40a and the forward end of the 
tubing 50 is, when properly primed, connected to the body of the patient. 
Removal of the syringe 40,40a from the injector 10 proceeds in the reverse, 
except that it is preferred that the tube 50 remain connected to the tip 
of the syringe 40,40a when the syringe 40, 40a is removed from the 
injector 10, to be disposed of along with the syringe 40,40a. Accordingly, 
the lever 26 is first moved from its locked to its unlocked positions 
(FIG. 3A to FIG. 3), whereupon the holder 32,32a is then pivoted to its 
loading position (FIGS. 1 and 1A). With the holder 32,32a in its loading 
position, the syringe 40,40a is withdrawn rearwardly from the opening 
39,39a of the holder 32,32a and the tubing 50 is slipped sideways from the 
opening 39,39a and outwardly through the slot 54,54a, as illustrated in 
both FIGS. 1 and 1A.