Note: Descriptions are shown in the official language in which they were submitted.
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B~CKGROUND OF THh INVENTION
The present invention relates to pumping devices, and
more particularly to syringes.
Syringes are in common use today by physicians, nurses,
and other hospital personnel for a variety of purposes. Fre-
quently, syringes have been utilized to pump fluid into a body
cavity of a patient or a cavity in a therapeutic device under cir-
cumstances where the pressure attained in the cavity should be
limited to a predetermined value. ~or example, duriny a spinal
anesthesia procedure an anesthetic solution is pumped ~rom a syr-
inge through a needle into the sub dural space which is e~senti-
ally an inelastic pouch, and thus only a specified maximum amount
of the solution should be pumped into the space as determined by
the pressure in the space. Similarly, various types of cardio-
vascular catheters are o~ten threaded into blood vessels, after
which a balloon adjacent the distal end of the catheter is
inflated through use o~ a syringe. If the balloon is overin-
flated, particularly when the catheter is placed in a smaller
vessel~ the vessel may be ruptured. Numerous other catheters,
such as endotracheal tubes and Foley catheters, are frequently
provided with retention balloons which should not be overinflated,
particularly when the balloon is obstructed by a body passage.
Few o~ the hospital personnel realize the considerable
pressures which can be generated by a hand-operated syringe. ~or
example, a 10 c.c. syringe may readily generate pressures in the
range of 50-60 lbs./sq. in., the smaller syringes being capable
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of developin~ greater pressures ~or the same amount of force ap-
plied~to the syringe plunger. It is thus apparent that consider-
abla care must be exercised by the user when a syringe is utilized
to pump fluid into a cavity space where only a limited amount of
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pressure is desired. In the past, tactile sense has been us~d
when forcing the plunger into the syringe to determine when the
maximum pressure has been attained by resistance to plunger move-
ment. Such a procedure produces spleculative results, at best,
in preventing harm to the patient, particularly since the syringe
may readily generate relatively hiy:h pressures.
SUMMARY OF T~E INVENTION
A principle feature of the present invention is the
provision of a syringe assembly of simplified construction which
prevents damage to a patient during use.
The syringe assembly of the present .invention comprises,
a syringe haviny a chamber for retaining fluid, and a plunger hav-
ing one end recelved in the chamber for pumping fluid out of t'he
chamber. The syringe ass~mbly has means for limiting the amount
of pressure ~enexated by the'syrinye'during pumping of fluid.
.Thus, a feature of .the present .invention is that *he
syringe assembly prevents gençration of an excessive amount of
pressure during use to prevent possible ~amage to the patient
Another feature of the .invention is that.the limiting
means actuates at a predetermined pressure to relieve pressure in
the syringe chamber.
A further. feature of the invention is that.the syringe
assembly may provide means for .indicating when the predete.rmined
; amount of psessurle has been attained.
~ Still a:nother feature of the :invention is that in one
' embodiment the li~miting means is associat~d with'an extension of
: a syringe barrel Idefining the syringe 'chamber.
' A feature of the'.invention is that in one embodiment
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the 'limiting means is associated with an adapter for the syringe.
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Yet another feature of the inventioll is that in one
emhodiment the limiting means prevents movement of the plunger
into the syringe chamber when the predetermined amount of pres-
sure has been attained.
A further feature of the present invention is the provi-
sion of a method for performing an epidural and a ~pinal anesthesia
procedure.
Further features will become more fully apparent in the
following description of the embodLmenks of this invention and
from the appended claims.
DESCRIPTION OF T~IE DRAWINGS
In the drawinys:
Fig. 1 is a sectional view of one embodiment of the syr-
inge assembly of the present invention as attached to a hollow
' 15 needle;
Fig. 2 is a fra~mentaxy sectional view of pressure limit-
ing means in the syringe assembly of Fig. 1 as actuated above a
predetermined pressure;
Fig. 3 is a fragmentary elevational view of the syringe
assembly of Fig. l;
' Fig. 4 is a fragmentary sectional view of another embodi-,~ ~ ment of the syringe assembIy of the prPsent invention as being
applied to a cathet'er;
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Fig~ 5 is a sectional view of an adapter in another
25~ ~, embodiment of the syringe assembly of the present invéntion;
Fig. 6 is a sectional view of an adapter in another '" ''"
`~ embodiment of the syringe'assembly of the present invention;
~ig. 7'is a sectional view taken substantially as indi-
cated along the'line'7-7 of Fig.'6;
Fig. 8 is -a sectional view ~f the adapter of Fig. 7
~ ; illustrating pre~ssure'limiting means as actuated above a pre-
'~ detexmined pressure;
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Flg. 9 is a sectional view oF a~ ~dDpter in ~nother
embodiment of the syrinye assembly of the present invention;
Fig. 10 is a sectional view of the adapter of Fig. 9
illustrating valve means in the adapter as actuated above a pre-
determined pressure;
Fig. 11 is a sectional view taken substantially as
indicated along the line 11-11 of Fig. 9;
Fig. 12 is a sectional view of another embodiment of a
syringe assembly of the present invention;
Fig. 13 is a sectional view of another em~odiment of a
syringe assembly of the present invention;
Fiq. 14 is a sectional view of an adapter in another
embodiment of the syringe assembly of the pxesent invention;
Fig. 15 is a fragmentary elevational view of another
1~ embodiment of a syringe assembly of the present invention;
Fig. 16 is a fragmentary sectional view o~ the syringe
assembly of Fig. 15;
Fig. 17 is a front plan view of another embodiment of
a ~yringe assembly of the present invention;
Fig. 18 is a fragmentary sectional view taken substan-
tially as indicated along the line 18~18 of Fig. 17; and
Figs. 19 and 20 are fragmentary sectional views of
additional embodiments of a syringe assembly of the present inve~n-
tion.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
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~ Re~erring now to Figs. 1-3, there is shown a syringe
,
assembly or syringe means generally designated 20 comprising a
syringe 22. The syringe 22 has a hollow barrel 24 having a cham-
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ber ~6 for retaining fluid. The syringe also has a plunger 28
having a fle~ible plug 30 ad~acent one end 32 of the plunger
received in one end of the chamber 26. The plug 30 sealingly
engages against the inner surface 33 of the syringe barrel 24,
5 with the plunger beiny pushed into the chamber 26 to purnp fluid
out of the chamber.
The syringe 22 has an extension or extension means 34
projecting from an end of the barrel 24 remote the plunger 28,
with the extension 34 having a tip 36 receivable in the huh H of
10 a hollow needle N. Of course, the tip 36 o the syringe exten-
sion 34 may be connected to any other suitable device, such as a
catheter, as described below. The extension 34 has a passage~"ay
38 which communicates with the syringe chamber 26 and the hollow
needle N, when attached, and has a flexible balloon ~0 which
15 communicates with the passageway 38 through an opening 42 in the
wall of the extension 34. The balloon 40 comprises a flexible
sleeve which surrounds the e~tension 3~, and has a pair of edges
44a and 44b secured to the outer surface of the extension 34 by
suitable means 46a and 46b, such as adhesive. Thus, the balloon
~o or sleeve 40 has its edges 44a and b sealed peripherally around
the extension 34, such that it defines a cavity 48 intermediate
the sleeve and the outer surface oE the extensi~on 34 which commu-
; ~ nicates through the opening 42 with the passageway 38.
The balloon 40 is constructed to inflate when a prede-
25 termined pressure has been reached in the passageway or chamber ofthe syringe, the particular pressure at which the balloon inflates
;~ being selected for the particular use contemplated for the syringe
assembly. The pressure at which the balloon inflates may be con-
trolled by a number of factors including the particular material
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used for the balloon, such as latex, and the thickness, durometer,
and elasticity of the balloon, as well as the transverse and longi-
tudinal radii of the balloon, accorcling to the law of I,aplace
which holds that the pressure required to inflate a balloon is
directionally proportional to its tangential tension and inversely
proportional to its transverse and :Longitudinal radii.
In use of the syringe for a spinal anesthesia procedure,
the chamber is filled with fluid, such as an anesthetic solution,
and the syringe tip 36 is attached to the hub H of the needle N,
after which the tip T of the needle may be advanced through the
tissue t, the potential epidural space e, and the dura mater d of
the patient's body, and inserted into the sub dural space s adja-
cent the spinal cord s'. The anesthetic solution is then ejected
from the syringe chamber 26 into the sub dural space s by pushing
the plunger 28 into the syringe chamber. Since the sub dural
space is essentially an inelastic blind pouch filled with fluid,
as shown in Fig. 1, and under'a positive pressure, the balloon 40
of the syringe is selected to inflate at a predetermined pressure
greater than the pressure in the sub dural space s. Consequently,
as the solution is pumped into the sub dural space, the pressure
builds up in the space until it reaches the predetermined pressure,
after which the balloon 40 inflates, as shown in Fig. 2, and
relieves pressure build up in the space, thus preventing harm to
the patient. Accordingly, the balloon 40 serves to limit the
~25 amount of pressure generated by the syringe, and prevents ejection
of further fluid into the needle N and sub dural space after the
predetermined pressure has been attained. The inflated balloon
also serves as an indication to the user that the predetermined
amount of pressure in the space or cavity has been reached, and
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that the plun~er should not be pushed further into the syringe
chamber 26.
Another embodiment of the syringe assembly 20 of the
present invention is illustrated in Fig~ 4, in which like refex-
ence numerals designate like parts. In this embodiment, the exten-
sion means 34 includes an adapter 'iO. If desired, a conventional
syringe 22 may be used having a standard luer tip 36'. The adapter
50 has a tip 36 adjacent one end for connection to a catheter C',
or other suitable device, such as the needle N, and a recess 52
adjacent the other end of the adapter for attachment to the tip 36'
of the syrinye 22. A passageway 38 extends longitudinally through
the adapter 50, and communicates between the syringe chamber 26 and
the catheter C' when the ends of the adapter are connected to the
- syringe and catheter. The adapter 50 has a flexible sleeve or bal-
loon 40 extending around the adapter and having its ends 44a and b
secured peripherally around the outer surface of the adapter by
suitable means 46a and b, such as adhesive. The sleeve 40 defines
a cavity 48 intermediate the sleeve and the outer surface of the
adapter 50 which communicates with the passageway 38 through the
opening 42.
; In use, after the syringe has been filled with fluid,
,
the adapter 50 i~ attached to the tip 36' of the syringe 22, and
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the tip 36 of the adapter 50 is attached to the cathe~er C'. The
~ ; catheter may be o a type having a lumen L which communicates
`~ 2S between a proximal end P of the catheter and a cavity C'' underly- -
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~ ing a balloon B adjacent a distal end D of the catheter. For a
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cardiovascular catheter, as shown, the catheter is previously
threaded through a vessel, and the balloon B is inflated through
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the lumen L by pumping fluid from the syringe chamber 26. When
the partially inflated balloon B becomes obstructed by the wall
of the vessel, and a predetermined amount of pressure is developed
in the cavity Cl' defined by the balloon B, the flexible sleeve 40
inflates to limit the amount of pressure generated by the syringe
and prevent overinElation of the balloon B, which otherwi.se might
- rupture the vessel~
It is apparent that-the pressure limiting or indicating
means associated with the syringe assembly of the present inven-
tion may be incorporated directly onto the syringe itself, aspreviously described, or may be placed on the adapter which is
connected to the syringe. In either case, the device operates in
a similax manner to prevent harm to the patient. Thus, for pur-
poses of previous and future discussion, it is i}~material whether
the limiting or indicating means is associated with the adapter
or the syringe itself in the syringe assembly, with the excep$ion
of the devices described in connection with Figs. 12 and 13.
Another embodiment o~ the adapter 50 in the syringe
assembly 20 is illustrated in Fig. 5, in which like reference
numerals designate like parts~ In this embodiment, the adapter
50 includes an outwardly extending thumb 56 having a channel 58
communicating with the passageway 38. The adapter 50 has a flex-
ible sleeve 40 extending peripherally around the thumb 56 and
hav~ng~its edges 44a and b secured peripherally around the thumb
~25 by means 46a and b, such as adhesive, thus defining a cavity 48
.~ .
~communicating with the channel 58 and passageway 38 through the
opening 420 The sleeve or balloon 40 inflates, as previously
described~in cormection with the syringe assembly of Figs. 1-4,
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to limit the amount of pressure gerlerated in the passageway 38
and the syringe chamber.
A further embodiment of the adapter 50 in the syrinye
assembly 20 of the present invention is illustrated in Figs. 6-8,
in which like reference numerals designate li.ke parts. In this
embodiment, a balloon 40' has its peripheral edyes 44' sealed by
suitable means 46', such as adhesive, to an outer surface 60 of
the adapter 50 to define the cavity 4~, which communicates with
the passageway through the opening 42. As shown in Fig. 8, the
balloon 40' inflates at a predetermi.ned pressure, as previously
described, to limit the amount of pressure generated by the
syringe assembly.
Another embodiment of the adapter 50 in the syringe
assembly 20 of the present invention is illustrated in Figs. 9-11,
in which like reference numerals designate like parts. In this.
embodiment~ a valve element 64 is supported in a chamber 66, with
: a head 67 of the valve elemen~ 64 having a face 68 for sealing
. against a seat 70 in the chamber 66. The head 67 has a stem 72
extending from an end of the head remote the face 68, with the
stem 72 being received in a cavity 74 in the adapter 50. A heli-
: cal spring 76 surrounds the stems 72 and extends between a back .-
;~ surface 78 of the cavity 7~ and a back surface 80 of the head 67.
~ The adapter 50 has a channel 82 communicating between the passage-
:~ way 38 and the chamber 66 adjacent the seat 70, and a pair of
.
channels:84a and 84b communicating between the chamber 66 and an
~ outer sur~ace 86 of the adapter 50. As illustrated in Fig. 9,
.~ the spring 76 biases the head 67 of the valve element to a first
~ position with the face 68 sealing against the seat 70 to pr~vent
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passage of fluid from the channel 82 into the chamber 66. How-
ever, when a predetermined amount of pressure is reached in the
passageway 38, the spring 74 permits movement of the valve ele-
ment to a second position with the face 68 of the head 67 spaced
from the seat 70, as shown in Fig. 10, and fluid then passes from
the passageway 38 through the channel 82, chamber 66, and the
channels 84a and b to the outer surface 86 of the adapter 50, as
indicated by the direction of the arrows in the drawing. Thus,
the valve means is actuated at a predetermined pressure to
relieve pressure in the passageway 38, and limit the amount of
pressure generated by the syringe assembly. The pressure at
which the valve means is actuated may be selected by the particu-
lar structure of the valve assembly, such as the particular heli-
cal spring 74 utilized in the adapter 50.
Another embodiment of khe syringe assembly 20 of the
present invention is illustrated in Fig. 14, in which like refer-
ence numerals designate like parts. In this embodimentl the
adapter 50 has an outer transparent cylindrical shield 51 defin-
ing a chamber 53, and a pair of extensions 55a and 55b extending
into the chamber 53 and partially defining the passageway 38'.
The tubular sleeve 40 has its ends received on the extensions
55a and b and secured in place by suitable means 46a and b, such
as adhesive. The sleeve 40 expands to limit the amount of pres-
sure generated by the syringe assembly, as previously described,
and is visible to the user through the transparent shield to
~ determine when the sleeve has expanded. The shield serves to
; protect the sleeve, and air is permitted to pass from the cham-
ber 53 through a vent 57 in the shield to permit expansion of
the sleeve.
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Another embodiment of the syringe assembly 20 of the
present invention is illustrated in Figs. 15 and 16, in ~hich
like reference numerals designate like parts. In this embodiment,
the flexible balloon or sleeve 40 extends around the syringe bar-
rel 24. The sleeve 40 is secured to an outer surface 152 of the
syringe 22 by suitable means 46a and b, such as adhesive, adja-
cent the edges 44a and b of the sleeve 40, in order to define a
cavity 48 intermediate the sleeve 40 and barrel 24 which communi-
cates with the syringe chamber 26 through an opening 42 in the
barrel 24. The sleeve 40 inflates above a predetermined pressure,
as previously described, to limit the amount of pressure generated
by the syringe.
Another embodiment of the syrinye assembly of the pres-
ent invention is illustrated in Figs. 17 and 18, in which like
reference numerals designate like parts. In this embodiment, a
balloon 40' has its peripheral edges 44' sealed by suitable means
46', such as adhesive, to the outer surface 152 of the syringe 22
to define the cavity 48, which communicates with the chamber 26
through the opening 42. The balloon 40' inflates at a predeter-
mined pressure, as previously described to limit the amount of
pressure generated by the syringe.
Another embodiment of the syringe assembly 20 of the
present invention is illustrated in Fig. 19, in which like refer-
- ence numerals des:ignate like parts. In this embodiment, the
extensions 34 described in connection with Figs. 4-14 may be
p~rmanently affixed to the syringe tip 36' by suitable means 150,
such as adhesive. As shown in Fig. 20, the extensions 34 may be
constructed as an integral part of the syringe 22, if desired.
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Another embod.iment of the syxinge assembly of the pres-
ent invention is illustrated in Fig. 12, in which like reference
numerals designate.like parts. In this ernbodiment, the barrel
24 of the syringe 22 is transparent, and the plunger 28 has a
flexible plug 30 adjacent the one plunger end 32 which is
received in the syringe chamber 26. The one end 32 of the
plunger 28 includes a centrally located transparent member 90
having a cavity 92 facing the syringe chambex 26, with .the trans-
parent member 90 being visible through the-barrel 24. A flexible
diaphragm 94 is supported by the .plug 30 and extends across an
opening 96 intermediate the cavity 92 in the transparent member
90 and the syrinye chamber 26. When a predetermined pressure has
been attained in the syringe chamber 26, the'diaphra~m 94 flexes
from a first po'sition adjacent .the opening 96, as shown by solid
lines in the drawing, to a second position received in the
transparent member 90,,as shown hy dotted lines in the'drawing.
The diaphragm 94 is thus visible to the user in its second posi-
tion and serves as an indication that .the predetermined amount
of pressure has been reached in the syrinye chamber., and that
the user should cease pumping the syringe.
~ A further embodiment of the syringe assembly of the
; present inventio~ is illustrated in Fig. 13, in which'like refer-
ence numerals designate like parts. In this embodiment, the
plunger 28 has a flexible plug 30'. adjacent .the one plunger end
32'which seals against the inner surface 33 of the barreI 24.
' The plug 30' has an annular slot 100 having one end 102.communi- '
`' cating with the syringe cavity 2~, and defining an annular flex-
ible side wall llD4 of the plug 30' adjacent .the inner surface 33'
~ of the syringe barrel 24. The'side wall 104 of the plug 30'
:~ 30 flexes responsive'to a predetermined pressure'in the:syringe'
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chamber 26, ~nd engages against the inner surface 33 of the syr-
inge barrel 24 to impede movement of the plunger into the syringe
char~ber. Thus, when the predetermined amount of pressure is gen-
erated by the syringe, resistance to movement of the syringe
plunger 28 into the syringe barrel 24 becomes noticeable to the
user, and movement of the plunger is then stopped to prevent dam-
age to the patient.
Thus, there has been described a syringe as.sembly which
has means for limiting the amount of pressure generated by the
syringe. assembly to prevent harm to a patient. In addition, the
syringe assembly indicates to the user when the predetermined
amount of pressure has been reached.
According to the present invention, methods are also pro-
vided for performing an epidural and a spinal anesthesia procedure.
In a spinal anesthesia procedure, the tip of a needle, used to per-
form the procedure, is advanced through the body tissue t, the
epidural space e, which is at a slight negative pressure, and the
dura mater d into the sub dural space s, which is at a positive
pressure, as previously described in connection with Fig. 1.
According to a method of the present invention, a balloon of the
adapter in the syringe assembly is ~elected to inflate at a first
predetermined pressure less than the pressure in the sub dural
~; space, and a balloon on the syringe, which is removably attached
to the adapter, is selected to inflate at a second predetermined
pressure greater than the pressure in the sub dural space. When
the needle tip T pierces the dura mater d and enters the sub dural
space s, fluid in the space actuates the balloon on the adapter
due to the higher pressure in the space relative the fixst pre-
determined pressure, thus indicating that the needle tip is at the
; 30 propex location in the space for performing the spin~l anesthesia
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procedure. The adapter may be removed from the needle and syringe,
and the syringe is attached to the needle to eject anesthetic solu-
tion into the sub dural space. The balloon on the syringe limits
the amount of pressure generated by the syxinge to prevent harm to
the patient, as previously described.
Alternatively, first and second adapter~ may be used in
conjunction with a standard syringe, the first adapter having a
balloon inflatable at thè fixst predetermined pressure, and the
second adapter having a balloon inflatable at the second predeter-
mined pressure. The'balloon of the first adapter is utilized todetermine when the needle tip is located in the sub dural space,
after which the first adapter is replaced with the second adapter
for pumping the anesthetic solution into the space.
A method is also provided for performing an epidural
anesthesia procedure with the syringe as~embly of the present inven-
tion. After the tip of a needle, at~ached to a syringe or an adap-
ter and syringe, is advanced into the body tissue, the syringe
plunger is pushed sufficientLy into the syringe chamber to inflate
a balloon on the syringe assembly with anesthétic solution from the
chamber. The needle tip is then advanced toward the epidural
space. When the needle tip enters the epiduxal space'the'solution
~ from the ~yringe assembly flows into the space due to the pressure
J ~ generated by the inflated balloon relative the negative pressure
in the space. Thus, the balloon deflates and indicates to the user
25~ that the needle tip is properly located for performing the proce-
dure. The anest:hetic solution may then be'ejected from the'syringe
nto the 'epidural space. Accordingly, the method of the'invention
prevents the user from improperly puncturing the'dura mater during
the epidural anesthesia procedure.'
30~ The foreg~ing detailed de~cription is given or clear-
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ness of understanding only, and no unnecessary limitations
should be understood therefrom/ as modifications will be obvious
to those skilled in the art.
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