U.S. patent number 3,833,000 [Application Number 05/258,960] was granted by the patent office on 1974-09-03 for medical aspiration system.
Invention is credited to Henry Bridgman.
United States Patent |
3,833,000 |
Bridgman |
September 3, 1974 |
MEDICAL ASPIRATION SYSTEM
Abstract
A medical vacuum aspiration system preferably for use in vacuum
abortions and diagnostics. The system is designed for operation at
high vacuum and includes a single transparent container which
provides the reservoir of vacuum, the chamber for collecting the
aspirated products, a trap for the collection of tissue and the
handle for the cannula. The container is provided with a cap and
valve on which the cannula is directly mounted. The invention also
includes a preferred method for producing high vacuum inside of the
chamber.
Inventors: |
Bridgman; Henry (Convent
Station, NJ) |
Family
ID: |
22982867 |
Appl.
No.: |
05/258,960 |
Filed: |
June 2, 1972 |
Current U.S.
Class: |
604/118; 604/140;
604/248; 604/319 |
Current CPC
Class: |
A61B
10/0291 (20130101); A61M 1/79 (20210501); A61M
1/0003 (20130101); A61B 10/00 (20130101); A61B
17/22 (20130101) |
Current International
Class: |
A61B
17/22 (20060101); A61B 10/00 (20060101); A61M
1/00 (20060101); A61m 001/00 () |
Field of
Search: |
;128/2F,DIG.5,DIG.24,275-278 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Rosenbaum; Charles F.
Attorney, Agent or Firm: Plottel; Roland
Claims
What is claimed is:
1. A vacuum curettage aspiration system for removing fluids and
semi solids from a uterus comprising a collection bottle having a
volume in the range of 50 to 500 milliliters; a cap connectable to
said bottle; and an operator-operative valve mounted in said cap
and having a seat for receiving a cannula, said valve providing
on/off flow though passage from said cannula receiving seat to the
interior of said bottle of said curettage system for removing
fluids and semi solids from the uterus.
2. An apparatus according to claim 1 wherein said collection bottle
is made of a transparent material, and has such cross-sectional and
length dimensions that it may be readily manipulated by one
hand.
3. An apparatus accordingto claim 1 wherein said bottle has a
smooth cylindrical neck portion adjacent to said cap, about 2
inches in diameter, and 2 to 3 inches in length; and a body portion
about 21/2 and 31/2 inches in diameter and 3 inches in length with
a textured outer surface to facilitate gripping.
4. An apparatus according to claim 1 further comprising a tissue
trap assembly mounted inside said collection bottle at one opening
of said operator-operative valve.
5. A system according to claim 1 further comprising a negative
pressure gauge for measuring the vacuum in said system having an
input valve received in said cannula receiving seat and of such
dimensions to hermetically fit in said seat, the gauge measuring
the vacuum in said bottle by opening said valve and further
comprising an operator-operative bleeder for permitting the passage
of air into said vacuum bottle to lower residual vacuum level while
measuring the vacuum in said bottle.
6. A system according to claim 1 adapted for uterine aspiration and
wherein said system has a vacuum less than 0.2 atmosphere at the
commencement of a procedure.
7. A system according to claim 6 wherein said bottle has a vacuum
less than 0.1 atmosphere at the commencement of a procedure.
8. A system according to claim 1 wherein said bottle has a capacity
between 300 and 400 milliliters.
9. A system according to claim 1 wherein said bottle has a capacity
between 100 and 200 milliliters.
10. A vacuum aspiration system comprising a collection bottle; a
removable cap connectable to said bottle; and an operator-operative
valve mounted in said cap and having a seat for receiving a
cannula, said valve providing on/off flow through passage from said
cannula receiving seat to the interior of said bottle, said system
further includes a one-way relief valve means for permitting the
passage of entrapped air and steam from the bottle into the ambient
atmosphere.
11. An apparatus according to claim 10 wherein said one-way relief
valve means comprises a weighted check of such dimensions that it
fits into said cannula receiving seat, whereby when said apparatus
with the valve open is slightly filled with water and heated and
steam is generated inside said bottle, said steam pushes entrapped
air and steam against said weighted check and escapes, and when
said apparatus is cooled, said weighted check is drawn tightly
closed by atmospheric pressure through condensation of the steam
inside said bottle.
12. A system according to claim 10 wherein said operator-operative
valve has a housing with a central passageway extending from inside
said cap to said cannula receiving seat, a transverse bore
intersecting said central passageway, a spool ratatably mounted in
said transverse bore having first and second passageways, and a
handle connected to said spool for operator-operatively moving said
ratatable spool between a first and second position;
said one-way relief valve means includes a one-way valve connection
extending from said transverse bore through said housing, said
one-way valve permitting a unidirectional passage of gasses from
said transverse bore to an outside of said housing; and
said first passageway of said spool having a diameter equal to, and
having its axis coplanar with the axis of said central passageway,
and providing said open flow through passage from said cannual
receiving seat to said bottle interior with said rotatable spool in
said first position, and blocking said flow-through passage when in
said second position; said second passageway of said spool
extending from said first passageway to a side of said rotatable
spool and providing another flow through passage from said inside
of said bottle through said first passageway and said one-way valve
to the outside of the housing with said rotatable spool in said
second position.
13. An apparatus according to claim 12 wherein the axis of said
central passageway, said transverse bore and said one-way valve are
perpendicular to one another.
14. An apparatus comprising a collection bottle; a removable cap
connectable to said bottle; and an operator-operative valve mounted
in said cap and having a seat for receiving a cannula, said valve
providing on/off flow through passage from said cannula receiving
seat to the interior of said bottle; a tissue trap assembly mounted
inside said collection bottle at one opening of said
operator-operative valve; said tissue trap assembly includes a snap
connection on the inside of said cap; a transparent tube
connectable to said snap connection and extending into said bottle;
and a gauze sleeve longer than said tube and extending
therethrough, one end of said sleeve being folded over said snap
connectable end of said tube and another end of said sleeve being
closed and protruding from the opposite end of said tube.
15. A vacuum curettage aspiration system for removing fluids and
semi solids from the uterine cavity consisting of a hermetically
tight collection bottle having a volume in the range of 50 to 500
milliliters and cap and having an operator-operative valve mounted
in said cap, and said valve including a seat for receiving a
cannula and providing on/off flow through passage from said cannula
receiving seat to said collection bottle, said system having a
vacuum less than 0.1 atmospheres at the commencement of a
procedure.
Description
This invention relates generally to medical aspiration equipment,
and to methods for preparing such equipment for proper surgical
use. The invention will find particular application in uterine
aspiration such as for vacuum abortions or sampling of tissue for
endometrial cancer detection.
Within the past seventeen years a technique called uterine
aspiration or vacuum curettage has been developed for performing
abortions during the early months of pregnancy. The earliest
reference to this technique appeared in an article by Y. T. Wu and
H. C. Wu, entitled "Suction in Artificial Abortion-- 300 Cases" in
the Chinese Journal of obstetrics and Gynecology, Vol. 6, 1958,
beginning at page 447. A recent survey of the subject appeared in
an article by Kerslake and Casey, entitled, "Abortion Induced by
Means Of Uterine Aspirator" in Obstetrics and Gynecology, Vol. 30,
July, 1967, pages 35-45. Very briefly, the technique described in
the Kerslake and Casey article is to aspirate the conceptus from
the uterus using a tube which has a flexible connection to a source
of suction. A typical apparatus as described in the article
includes a suction curette having an oval mouth at its end, or on
one side, and an air hole at the other end to control the suction.
A rubber suction tubing connects the curette to a glass container
which in turn is connected to a source of suction. Aspiration of
the uterine contents usually takes less than 2 minutes and the
fetal material can readily be seen as it appears in the glass
container. The method employed may be very briefly reviewed. The
perineum, vagina, and cervix are disinfected. The cervis is then
drawn forward with a tenaculum. The direction of the cervical canal
and the depths of the uterine cavity are determined with a uterine
sound. It is a common practice to dilate the cervix to allow easy
insertion of the suction curette. When dilation is required,
preferably a local anesthesia is administered. General anesthesia
is rarely used. The suction curette of appropriate diameter and
design is inserted carefully through the cervix into the uterus.
The suction is then started. In a few seconds the suction reaches a
working level which, according to the Kerslake and Casey article,
is at a mean level of 18 inches of mercury (relative). The suction
curette is moved gently up and down over all aspects of the uterine
cavity. The products of conception pass visibly into the glass
container either whole or piecemeal. The degree of suction can be
controlled with some aspirators by putting a thumb over an airhole
at the base of the curette as well as by using a pressure control
device on the pump. During the aspiration process, the uterus
reacts by contracting and decreasing in volume. Aspiration usually
takes less than a minute or two. It is thought to be complete when
the uterine wall fells smooth and no further remnants emerge. A
TYPICAL PRIOR ART APPARATUS used for uterine aspiration consists of
a curette connected by a hose to a collection bottle which in turn
is connected by a second hose to a vacuum source.
In the prior art system described by Kerslake and Casey the source
of the vacuum or suction, the collection bottle, and the curette of
cannula, are connected by hoses or pressure tubing. The working
level of vacuum or suction typically is 15 to 18 inches of mercury
(relative) and is gradually raised to this level after the curette
is inserted into the uterus.
Uterine aspiration, is not limited to abortions, but is a general
technique with a further application in diagnostics. For example,
in a recent article by B. A. BJerre, et al., entitled "Aspiration
curettage -- A New Niagnostic Method" in the Journal of
Reproductive Medicine, Vol. 7, No. 5, Nov. 1971, the technique of
aspiration curettage was recommended for routine use in collecting
tissue for endometrial diagnosis and other diagnostic purposes.
Here the curette is of a small outside diameter, typically 3mm,
welded to a plastic cap of a tubular chamber which in turn is
connected to a suction pump. The plastic chamber contains a
perforated plastic cylinder that serves as a filter and arrests
mucosal fragments which are to be laboratory tested for either
polyps, endometrial "atypia," or an adenocarcinoma. The technique
employed in the diagnostic aspiration curettage is similar to that
employed for the abortions by vacuum curettage. Here the vagina and
portico are cleaned, typically with soap. The portico is gripped
with a tenacucoum forceps; a uterine sound is passed in the cervix
and without further dilation the curette is advanced into the
fundus. Suction is introduced and the curette is passed over the
entire uterine walls; tissue and some blood is scraped from the
uterine wall and aspirated by suction. The tissue is trapped in the
tubular chamber and a histopathological examination is subsequently
done on the aspirated and trapped tissue.
In one embodiment of the present invention a high vacuum is used,
e.g., 28 to 30 inches of mercury, which is applied with full
strength at the very beginning of the procedure. By using this high
vacuum, it is possible to construct an aspiration system in which
the collection bottle, source of vacuum, and handle for the curette
are all one. This does away with a separate source of suction,
whether that be an electric pump (which is commonly used in the
United States), or a vacuum jar (as used in China). It might be
noted that electric pumps are subject to failure -- due to
electrical interuptions, or to accidental carry-over of fluids from
the collection bottle -- with the very serious consequence that the
procedure is interupted and has to be completed by sharp D & C
or in extreme cases by a hysterectomy. The system of the invention,
moreover, does away with the prior art hoses which connect the
curette to the collection bottle and the collection bottle to the
suction source. These hoses encumber the physician. Furthermore, if
the curette is not provided with a handle and swivel, which are
heavy, it is difficult to rotate the curette in the uterus. This
feature is considered very desirable by many surgeons. In the
present invention there are no encumbering hoses, and the surgeon
may rotate the curette easily without heavy swivels or other
attachments.
In one embodiment of the invention, a high vacuum is induced in a
transparent bottle typically less than one-half liter in volume. A
cap with a valve is mounted on this bottle and a cannula or curette
rigidly fits into a seat on the valve. In a typical procedure, the
cannula is introduced into the uterus, the valve is then opened and
the full vacuum rapidly sucks the products of conception from
theinterior of the uterus. The surgeon may grasp the bottle in one
or both of his hands and move the cannula tip over the wall of the
uterus. The valve is then closed, and the apparatus is
withdrawn.
It will be noted that the apparatus is relatively small. The volume
of a typical bottle is 0.35 liters, small enough to be conveniently
held in a surgeon's hand. This size is possible because of (1)THE
INITIAL HIGH VACUUM AND (2) the absence of hoses, which dilute
residual vacuum by reason of expansion, and (3) the discovery that
the material extracted from the uterus is a fluid with virtually no
gas content. The latter point might be examined a little more
fully. The products of conception extracted from the uterus is a
fluid with entrained semi-solids. This apparently was not
previously appreciated, nor was it applied to the practical design
of uterine aspiration apparatus. Experimentation has confirmed that
the collection bottle may be filled approximately 70 full with
aspirated material before the pre-induced vacuum level falls more
than 12 percent. (In one measurement, a 475 milliliter container
starting with an initial vacuum of 28.64 inches of mercury was
filled to 400 milliliters and had a remaining vacuum of 26.85
inches of mercury. When subsequently filled to 450 milliliters, it
still had 23.34 inches of mercury vacuum). The important point is
that it is not until the aspirated volume reaches about 70 percent
of collection bottle volume that the initial induced vacuum begins
to deteriorate appreciatly. This fact apparently had not been
appreciated nor was it applied heretofore to uterine aspiration
systems.
A further advantage of the system of the present invention is that
the aspirated products may be easily observed by the physician
because the collection bottle is attached directly to the cannula
and is in this hand during the procedure. In prior art abortion
systems the collection bottle is remotely positioned. When
connected by a hose, the collection bottle -- in order to avoid
being accidentally toppled over when the hose was pulled on -- is
securely mounted onto a stable platform which is usually some
distance away and the physician has to look up and away from the
patient and the point of operation to see the aspirated material.
With the apparatus of the present invention, the doctor applies his
sense of touch to the collection bottle, and also concentrates
visually on the collection bottle to observe the products of
conception being removed.
A further advantage of the present invention, is lack of dependence
on the electric vacuum pump. In addition to mechanical failure,
possible contamination, and electric power failure, the pump has
the further drawback in that its noise is psychologically upsetting
and stress-producing on the patient. It has been observed that when
the pump is turned on and running, the patient reacts with an
undesirable tension, complicating the emotional, as well as the
physical completion of the operation. The system of the present
invention it will be noted is completely silent.
It may be noted that this embodiment of the invention has the
further advantages of being compact in that it occupies but a small
volume, and it is simple to assemble, disassemble and clean as well
as to operate.
The initial vacuum in the bottle of this system may be induced by
an electric pump, or by any other mechanical means. A preferred
method according to the present invention of producing a very high
vacuum, e.g., 28-30 inches of mercury in the collection bottle
itself includes the steps of placing a small amount of water inside
the bottle, heating the water so as to cause it to boil and fill
the jar with saturated steam, thereby driving the entrapped air out
of the bottle, then closing the valve on the bottlecap to trap the
steam, and then cooling the steam and bottle. As the stem condenses
a nearly perfect vacuum is produced. This method may be employed in
those areas where electric or mechanical pumps are inconvenient or
untenable. It may find particular application in emergency
situations, or in areas where electricity of appropriate
characteristic is unavailable. The only requirement for producing
high vacuum by this method is enough heat to boil water. It may be
further noted that this preferred method sterilizes the collection
bottle, as well as the valve fitting through which the stem is
passing.
When the thermodynamic method of forming a high vacuum is used, the
apparatus of the present invention may include a relief valve for
permitting the steam to escape, and various modifications and
embodiments of such relief valves are described herein.
A further aspect of the present invention is a novel filter or trap
for collecting the semi-solid parts extracted during an aspiration.
The novel trap has the advantage of both a flexible trap, as well
as a rigid trap. The advantages of the former are that it can be
easily emptied so that the solid parts may be spread out in a pan
to perform the fetal parts count. The novel trap may be
disconnected and set aside should the surgeon decide that he does
not wish to use a trap.
The novel trap is particularly useful with the high vacuum
available with the apparatus of this invention in that the solid
and liquid parts are drawn into the collection bottle at a high
velocity, thereby moving the solid parts into the bottom of the
trap and away from the entrance to the collection bottle.
Other objects and features of the invention disclosed will become
apparent to those skilled in the art upon reference to the
following specifications and accompanying drawings wherein several
embodiments are disclosed by way of illustration.
IN THE DRAWINGS
FIG. 1 is a plane view of a preferred embodiment of the invention,
and auxiliary apparatus that may be used therewith.
FIG. 2 is a perspective view of a partially assembled trap for use
in the apparatus of FIG. 1.
FIG. 3 is a graph illustrating the relation between pressure
(vacuum) remaining in the bottle in terms of fluid volume
aspirated.
FIG. 4 is a perspective view of an alternative embodiment of a
portion of the cap valve socket assembly of FIG. 1.
FIG. 5 is a cross sectional view of a detail of the assembly of
FIG. 4.
Referring now to the drawing of FIG. 1, there is shown a preferred
embodiment of a collection apparatus of the invention, which will
find typical application in terminating early pregnancies. The
apparatus consists basically of three parts: a collection vacuum
bottle, 10, a cap valve socket assembly, 12, and a mesh filter or
trap, 14. A cannula 16, fits directly into a socket connection on
the cap valve socket assembly, 12. Two accessories are also shown
in FIG. 1. The first is a floating relief and check valve, 18,
which may be used when the vacuum in the collection bottle is to be
produced thermodynamically, as described more fully below. The
second, is a test gauge, 20, to measure the vacuum in the
collection bottle, and which is more fully described below.
The collection bottle itself, 10, is preferably made of a clear
(i.e., transparent) heat resistent material (e.g., Pyrex). The
dimensions of the collection bottle are such that it may be
conveniently hand-held. A preferred bottle has a lower portion, 22,
which is larger than its upper portion, 24. A checkered or textured
surface, 26, may be provided on the lower portion, 22, of the
bottle, to facilitate gripping. A typical bottle is 61/2 inches
long, with the upper portion 21/4 inches in diameter and the lower
portion 21/2 to 3 inches in diameter. During a procedure that the
bottle is held in one hand and manipulated. Alternatively, the
surgeon may loosely hold the upper portion in one hand, and graps
the lower portion with his other hand, swivelling the apparatus so
as to move the cannula tip over the wall of the uterus. It should
be noted that the assembled apparatus includes the cannular rigidly
connected to the collection bottle so that the bottle in addition
to being the collection chamber, and the reservoir of the vacuum,
is also the handle for the cannula. It should be further noted that
the collection bottle during the procedure is in the hands of the
surgeon and the extracted products of conception can be readily
viewed through its transparent walls by the doctor as he performs
the operation.
The upper end of the bottle terminates in a screw fitting, 28,
which mechanically mates with a corresponding fitting on the cap
valve socket assembly, 12. It should be understood, however, that
any convenient or conventional fitting may be used so long as the
connection is vacuum tight, and for certain embodiments, are also
heat resistent.
The cap valve socket assembly, 12, includes a cap portion, 30,
which connects to the screw thread, 28, on the upper portion of the
bottle. A plug valve, 32, is mounted on the cap, 30, and terminates
in a suction curette socket connection, 34. The cannula or curette,
16, fits directly into the socket connection, 34, and is secured
tightly therein by either a friction fit, as is common with many
curettes commercially available, or by any other convenient or
conventional securing means. The plug valve, 34, includes a handle,
36, which is movable between first and second positions to permit,
or to block, a freeflow having at least 3/8 inches diameter passage
from the socket connection at 34, to the interior of the bottle at
the inside of the cap, 30.
The mesh filter or trap, 14, may be a rigid plastic or metal mesh
strainer which fits inside the collection bottle, and may be
attached either to the inner face of the cap, or along the
interspace between the cap and the top lip of the bottle. In
practice, the traps collect the fetal parts and other solid
material which are subsequently examined by the surgeon or
pathologist. In the case of endometrial tissue collection, it is
this tissue material which is sought for the subsequent diagnostic
testing. In the case of abortion the semi-solid material is
examined to make sure all of the products of conception have been
removed.
A preferred trap, constructed in accordance with this invention, is
shown in perspective, partially assembled, in FIG. 2.
The trap includes a transparent cylindrical tube, 40, opened at
both ends, and provided with an outwardly protruding lip, 42, at
its upper edge. A tube receiving clip, 44, is mounted on the inside
of the cap, 30, encircling the lower end of the flow through
passage, and shown here as 46. The clip, 44, may be a resilient
plastic which engages and firmly grips the lip, 42, on the tube,
40, thus rigidly holding the tube onto the cap, 30. A loosely woven
tubular-shaped fabric, 48, open at its upper end, and closed at its
lower end, is positioned inside the tube, 40. The upper end is
folded over the upper lip, 42, extending approximately a half an
inch down from the top. The fabric, 48, is held in place by either
the natural spring of the fabric itself, or by a rubber band or
piece of string around the folded over fabric. The tube with the
fabric over its upper end fits onto the receiving clip, 44, on the
cap. The lower end of the fabric which is closed extends past the
lower end of the tube. During an operation, solid matter which is
aspirated, is retained in the fabric, 48, while liquid readily
passes therethrough. With this arrangement the advantages of both
the flexible and rigid collection traps are achieved. The tube, 40,
holds the fabric, 48, in the proper spacial position inside the
bottle, while preventing both clogging of the inside of the flow
through passage by the fabric and accumulation of collected
material at the passage opening, 46. The aspirated solids are in
the flexible fabric, 48, and the surgeon -- after he believes all
the products of conception have been aspirated, but while the
patient is still in the operating room -- may open the collection
bottle, snap off the tube, 40, with the fabric, 48, pull out the
fabric, 48, and turn it inside out, thus very rapidly freeing all
the solid material. The fetal parts count is then performed, with
the surgeon determining whether all material has been extracted,
and if necessary, he can go back and remove any remnants which were
missed. The speed with which the filter can be emptied, coupled
with the structure tht does not clog the filter, are thought to be
important.
In a typical procedure, the trap, 14, is connected and the cap
assembly, 12, is attached to the bottle, 10 (with the handle, 36,
in the open position). Vacuum is induced inside the bottle, 10, the
handle, 36, is closed. A sterile cannula, 16, is fitted into the
socket, 34, and the apparatus is ready for the procedure. After the
patient has been prepared, the cannula is introduced into the
uterus, and the surgeon opens the valve, 34, at the handle, 36; and
then, by manipulating the bottle, 10, with one or both hands, moves
the opened end of the cannula over the surface of the uterus wall,
extracting the conceptus. When all the material is believed to be
removed, the handle, 36, is closed, and the apparatus is removed.
In the case of endometrial tissue extraction, a similar routine is
followed.
The vacuum inside the bottle, 10, may be produced immediately
before the operation, by an electrical or mechanical pump.
Alternatively the apparatus may be vacuum pre-packaged with the
vacuum induced several weeks or months before the procedure and the
apparatus rests on the shelf until ready.
In a preferred method of the invention, the vacuum is produced
thermodynamically and preferably shortly before the operation. The
advantages of the thermodynamic process are many. First, a very
high vacuum is obtainable, on the order of 28 to 30 inches of
mercury (relative). Second, the technique sterilizes the entire
apparatus. Third, the vacuum may be produced without the need for
an external pump whether that pump be electrical or mechanical, and
thus does not rely upon electrical power or a source of mechanical
power. According to the preferred method, the valve cap socket
assembly, 12, with the attached trap, 14, is separated from the
bottle, 10, and several cubic centimeters of water (e.g., 2 to 4
cc's) are placed inside the bottle. The trap, 14, and socket
assembly, 12, are replaced, and the handle, 36, is in the open
position. Heat is applied to the bottle, 10, until the water inside
boils and steam issues steadily from the curette socket, 34. At
this point the apparatus is removed from the heat and the handle,
36, is quickly closed. As the assembly cools the condensing steam
induces the high vacuum inside the bottle, 10. The saturated steam
produced during heating drives out the entrained air, and the steam
when cooled, condenses to a very small volume, producing a very
high vacuum. The heat may be provided from any source, such as a
laboratory Bunsen Burner, an autoclave, or if used in the field, a
portable heating source, such as a sterno heater, or a kitchen
stove.
It has been discovered that the aspirated products have very
little, if any, gaseous content, and the high vacuum pre-induced
inside the collection bottle remains relatively stable until
approximately 70 percent has been filled with liquid and semi-solid
material. For example, with an initial vacuum of 28.43 inches of
mercury a collection bottle was filled 73 percent full and the
remaining vacuum was still 25 inches of mercury.
The relationship can be generalized and expressed mathematically as
follows:
Pr = [PaVf + Ps (V- Va)]/ [Vf + (V - Va)]
where
Pr = Pressure (vacuum remaining in collection bottle for any amount
of fluid volume aspirated).
Ps = Initial pressure in collection bottle (pre-induced
vacuum).
Pa = Atmospheric pressure.
V = volume of collection bottle.
Vf = Free volume between suction tip opening and valve.
Va = Fluid volume aspirated.
All Expressed in Absolute Units.
In the apparatus of the present invention the quantity Vf (the free
volume between the suction tip opening on the cannula and the
valve) is held to a minimum because there are neither hoses nor
intermediate connection between the cannula and the valve to
deplete the available vacuum. When Pr, (the vacuum remaining in the
collection bottle) is expressed in terms of Va (the fluid volume
aspirated) for any set of given conditions, it is found that Pr
does not change appreciably until the fluid volume aspirated
reaches about 70 percent of the collection bottle volume. Thus,
relatively large volumes of fluid may be aspirated at nearly
constant pre-induced vacuum levels. This relationship is shown
graphically in FIG. 3.
When the vacuum is produced thermodynamically, verious
modifications may be added to the apparatus. FIG. 1 shows the
floating relief and check valve, 18, which fits into the socket
connection, 34, and is placed in the socket connection, 34, just
before the bottle is heated. The valve, 18, is of sufficient weight
to remain in the recessed socket connection yet allow entrained air
and steam to escape during the heating cycle. When the heat is
discontinued, and the steam condenses, the valve, 18, is drawn
tightly into the socket, 34, by vacuum, and air is prevented from
entering the bottle. The apparatus is then cooled, the handle, 36,
is closed, and the valve, 18, is removed. With this arrangement,
the valve, 18, closes at the right moment, and an attendant does
not have to handle the apparatus while it is hot.
An alternative embodiment relief valve is shown in FIG. 4, which is
a perspective view of a portion of the cap valve socket assembly.
The handle, 36, is connected to a rotable spool, 50, which has
first and second passageways, 52 and 54. The first passageway, 52,
becomes aligned with a central passageway (flow through) of the
plug valve, 32, when the handle, 36, is in the open position (as
shown in this Figure). The second passageway, 54, is perpendicular
to the first passageway and extends to one side of the spool, where
a one-way valve, 56, is mounted in the side wall or housing of the
valve, 32. This one-way valve, 56, is of a kind which permits
passage of a low pressure air and steam from the inside of the
housing to the outside of the housing, but which blocks the passage
of air in the opposite direction. A detail of a cross-section of
the one-way valve, 56, is shown in FIG. 5, and includes a spring
loaded ball, 58, which presses against a seat or collar, 60. The
one-way valve, 56, is of a conventional design and any other
one-way valves which perform the same function may be used. The
advantage of the valve arrangement of FIGS. 4 and 5 is that when
steam is generated and the valve, 32 is in its closed position,
(i.e., the handle, 36, rotated 90.degree. downward and forward in
the drawing of FIG. 4 so that the spool 50 takes the position shown
in FIG. 5 the steam and entrained air will pass through the second
passageway, 54, into the large passageway, 52, and then through the
one-way valve, 56. When the apparatus is cooled, the one-way valve,
56, will not permit the return of air and the bottle is thus
effectively sealed and as the steam condenses, the vacuum builds.
It is not necessary for an attendant to handle the hot apparatus,
or close the hot valve.
A further accessory for use with the apparatus is shown in FIG. 1.
It is the vacuum test gauge, 20, which has a conventional vacuum
gauge, 70, connected to a lower mating plug, 72, which fits into
the socket, 34. The available vacuum can be measured without the
loss of any pressure, (other than the vacuum associated with the
gauge, 20, which is negligable) by placing the plug, 72, in the
socket, 34, and opening the handle, 36. The gauge, 20, is also
provided with a bleeder control knob, 74, which permits the
controlled introduction of ambient air into the collection bottle.
With this arrangement the vacuum inside the bottle may be adjusted
to a lower level, if desired, while monitoring the remaining
pressure on the gauge, 70.
An alternative gauge, 80, is shown in FIG. 1. It will find
particular application with pre-packaged vacuums that may remain on
the shelf for several weeks or months. Gauge 80, is a non-porous
elastic membrane, filled with a given quantity of gas. It is
positioned inside the bottle, 10. When there is vacuum in the
bottle, the membrane is completely inflated through the expansion
of entrapped air sealed in at atmospheric pressure. As the vacuum
decreases, the membrane correspondingly collapses. Thus, the size
of the membrane, 80, provides a rough indication of the amount of
vacuum remaining in the bottle. During a procedure, as the vacuum
bottle fills, the gauge, 80, provides a continuous measure of
remaining vacuum. This is possible because it is light and floats
on top of any collected liquids, and is always readily visible.
Although the invention has been described with examples applicable
to abortions, it is not so limited, and may find application
elsewhere. For example, where the apparatus is to be used for
endometrial cancer detection, or for removal of cysts and drain
other body cavities, different sized cannula, and different sized
collection bottles may be used. For example for endometrial testing
the cannula typically has an outside diameter of 3 mm (this may be
contrasted with the cannula used in the early weeks of pregnancy of
approximately 6 to 8 mm) and the collection bottle is small in
size, typically having a volume of about 100 ml.
Thus there has been shown and described a, uterine aspiration
system which is self-contained, easy to use and frees the doctor
from the encumbrances of connecting hoses, swivels, etc.
Furthermore, the collection bottle forms the "handle" of the
curette and thus not only provides a good support, but also permits
inspection of the extracted products during the procedure. The
apparatus of the invention moreover, does not depend upon an
electric pump as its source of vacuum during the operation, and
thus is free from the noise, and the resulting psychological stress
associated therewith and possibility of power failure. There has
also been explained that it is possible to perform the vacuum
curettage with a relatively small volume high vacuum collection
bottle
There has also been described a preferred method of producing the
high vacuum. This method does not rely upon electric pumps or
mechanical pumps, and may be produced in areas where electricity,
and machinery, is not available. The method is simple, and also
sterilizes the equipment. It will find particular application in
remote areas of the world, where electricity and electric pumps are
not readily available. There has also been described various
gauges, and accessory valves, for use with the apparatus of the
present invention.
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