U.S. patent number 3,885,549 [Application Number 05/474,236] was granted by the patent office on 1975-05-27 for apparatus for producing a vacuum in a test tube.
Invention is credited to David Thomas Green.
United States Patent |
3,885,549 |
Green |
May 27, 1975 |
Apparatus for producing a vacuum in a test tube
Abstract
Apparatus is provided for forming a vacuum in a test tube in the
field. A cap is mounted on an insertion tool by having a projection
on the tool cam out a detent on the cap as it passes. The cap is
then rammed into a test tube by use of the tool, a flange on the
cap bending back to permit air to escape. With the whole cap in the
tube, the detent is prevented from being cammed out, permitting the
tool to be used to withdraw the cap from the tube. As the cap is
withdrawn, the flange is forced against the walls of the tube to
prevent air reentering the tube. When the upper portion of the cap
leaves the tube, the detent is again cammed out by the projection
on the tool, releasing the tool. The lower portion of the cap,
including the flange, remains in the tube to seal it.
Inventors: |
Green; David Thomas (Norwalk,
CT) |
Family
ID: |
26951807 |
Appl.
No.: |
05/474,236 |
Filed: |
May 29, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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266396 |
Jun 26, 1972 |
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Current U.S.
Class: |
600/573; 604/228;
600/577 |
Current CPC
Class: |
A61B
5/15003 (20130101); F04B 37/14 (20130101); A61B
5/150503 (20130101); A61B 5/154 (20130101); A61B
5/150351 (20130101); A61B 5/150389 (20130101); A61B
5/150732 (20130101); A61B 5/150236 (20130101); A61B
5/150099 (20130101); A61B 5/150244 (20130101) |
Current International
Class: |
A61B
5/15 (20060101); F04B 37/14 (20060101); F04B
37/00 (20060101); A61b 005/14 (); A61m
001/00 () |
Field of
Search: |
;128/2F,DIG.5,275,276,278,220,218P,218D ;215/47 ;417/566 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Howell; Kyle L.
Attorney, Agent or Firm: Levinson, Esq.; Joseph
Parent Case Text
RELATED APPLICATIONS
This application is a continuation of my earlier copending
application, Ser. No. 266,396, filed June 26, 1972, and now
abandoned.
Claims
What is claimed is:
1. A device for forming a vacuum in a test tube when inserted,
moved along the length therein and then partially withdrawn
therefrom, the partial withdrawal sealing the test tube to maintain
the vacuum produced therein, comprising
a. a test tube which is desired to be evacuated having walls
therein,
b. a cap on said test tube having an integral body formed of a
cylindrically shaped upper portion sealed on one end thereof, and
an enlarged cylindrically shaped lower portion of diameter less
than that of said test tube, whereby said cap may be inserted,
moved therein, and partially withdrawn from said test tube,
c. a flexible flange ring formed as an integral part of said lower
portion, the diameter of said flange being greater than the
diameter of said test tube, said flexible flange being bent back on
said lower portion of said body when said cap is inserted and moved
along the length of said test tube, the pressure of air trapped
ahead of said cap forcing said flexible flange ring out of contact
with the walls of said test tube, allowing the trapped air to
escape between the walls of said test tube and the smaller diameter
of said integral body, said flexible flange contacting the walls of
said test tube as said cap is partially withdrawn thereform to
maintain the vacuum in said test tube below said cap,
d. an insertion tool having detachable mounting means positioned on
one end thereof engaging said cap and moving said cap in said test
tube, and
e. flexible detent means mounted on said upper portion of said body
engaging said detachable mounting means of said insertion tool,
said detent means and said detachable mounting means defining means
whereby said insertion tool remains mounted on said cap so long as
the walls of said test tube are in contact with said flexible
detent means, said flexible detent means releases said insertion
tool from said cap when said upper portion of said cap is removed
from said test tube, said flexible detent means being deflected by
said detachable mounting means on removal from said test tube,
thereby gripping the top of said test tube by said cap to prevent
said cap from moving back into said test tube which has been
evacuated thereby.
2. A device as claimed in claim 1 wherein said flexible detent
means comprise a pair of flexible detent means each mounted on a
web extending from said upper portion of said body.
3. A device as claimed in claim 2 wherein each of said flexible
detent means includes a cantilever arm extending from the
corresponding web with a projection having angled forward and
trailing edges mounted at the end of said cantilever arm.
4. The device claimed in claim 3 wherein said insertion tool
comprises a rod terminating in a pair of cantilever arms spaced
sufficiently to permit said webs of said body to pass between said
arms, and at least one projection having angled forward and
trailing edges mounted at the end of each arm adapted to deform
said flexible detent means thereby positioning said rod on said
cap.
5. A device as claimed in claim 1 wherein said flexible flange ring
has a ridged lower surface thereon.
6. A device as claimed in claim 1 including an annular groove
formed in said lower portion just above said flexible flange ring,
said groove receiving said flexible flange ring when said cap is
being inserted and moved in the test tube to permit air to pass
said flexible flange ring.
7. A device as claimed in claim 1 including a bore formed from said
seal in said upper portion through the remainder of said cap, and
including a rupturable seal formed across said bore at a point
along the length thereof, and a substance which is desired to be
mixed with a fluid which may be applied to said test tube being
stored in said bore above said seal.
Description
BACKGROUND OF THE INVENTION
This invention relates to apparatus for creating a vacuum in a test
tube and more particularly to such an apparatus which permits tests
tubes to be vacuumized in the field without requiring complex or
expensive equipment.
For many years sealed, vacuumized test tubes have been sold to
hospitals, doctors, and other medical organizations for use in
drawing blood and other biological samples. Vacuumized tubes have
been found preferable for these applications over standard
hypodermic needles or syringes for at least two reasons. First,
when a hypodermic needle is utilized to draw blood from a vein,
there is a possibility that a careless attendant might accidentally
depress the plunger while the needle is in the vein, injecting air
into the vein. Air inadvertently injected into an individual's
veins could result in a fatal stroke or embolism. Secondly,
depressing the hypodermic plunger to remove blood therefrom may
break up or otherwise damage corpuscles in the blood, introducing
the possibility of inaccurate test results. Similar problems may
exist when a hypodermic needle is utilized to draw other biological
samples.
While the prevacuumized test tubes presently available overcome the
problems indicated above, and have thus enjoyed substantial
commercial success, they do present certain problems. First, while
the cost of cleaning the tubes after use is relatively low, the
cost of shipping the tubes back to the manufacturer after use to be
revacuumized is high enough so that this procedure is not
economically feasible. Thus, most of the tubes are now thrown away
after a single use. Second, relatively expensive rubber caps must
be used rather than plastic caps to seal the tubes. This
requirement exists because plastic is slightly porous, and the
shelf life of a vacuumized tube with a plastic cap would thus be
minimal.
From the above it is apparent that the cost of utilizing vacuumized
test tubes could be substantially reduced if a procedure could be
provided for permitting the tubes to be revacuumized at the site.
Further, if the revacuumizing could be accomplished within a short
time before use (for example within a day or two before use)
relatively inexpensive plastic sealing caps could be substituted
for the rubber caps now utilized.
An additional problem which could be solved by providing a
capability of vacuumizing test tubes at the site is that of storing
cultures which can breed only in a vacuum. At present, expensive
equipment is required at facilities working with these
cultures.
Another shortcoming of existing pre-vacuumized test tubes is that,
where a substance such as an anti-coagulant is required to be mixed
with the biological sample applied to the tube, the substance is
normally placed in the tube before it is vacuumized and sits in the
bottom of the tube when the sample flows in. When a tube is filled,
the attendant must shake the tube to insure proper mixing of the
substance with the sample. Should the attendant inadvertently
forget to shake the tube after the sample is drawn, damage to the
sample may occur. Further, certain substances are of a type which
may not be stored in a vacuum, and the mixing of these samples
presents special problems with existing prevacummized tubes. A
requirement therefore exists for a procedure to permit the storage
of substances to be mixed with a biological sample under nonvacuum
conditions and in a manner so as to insure substantial mixing of
the substance and the sample.
SUMMARY OF THE INVENTION
In view of the above, this invention provides an apparatus for
forming a vacuum in a test tube and of sealing the tube. The
apparatus involves the use of a cap which is adaptable for use with
a simple insertion tool. The cap consists of a body formed of a
cylindrically shaped upper portion and an enlarged cylindrically
shaped lower portion with the diameter of the lower portion being
less than that of the test tube to be vacuumized. The upper portion
of the cap is sealed at its top and has an internal bore which
terminates in an enlarged counterbore in the lower portion. A
flexible flange ring is formed as an integral part of the base of
the lower portion, the diameter of the flange being greater than
the test tube diameter. A detent means is mounted on the upper
portion of the body, the detent means being shaped and positioned
to be cammed out of the way of the cap insertion tool to permit the
tool to be passed in or out of the cap when the upper portion of
the cap is out of the test tube. However, when the upper portion of
the cap is in the test tube, the walls of the test tube inhibit the
camming out of the detent means. Thus, the insertion tool is held
in the cap by the detent means so long as the upper portion of the
cap is in the test tube. This permits the cap to be lowered into
the test tube by the tool, with air escaping around the flange ring
as this is done. The tool is then used to draw the cap out of the
tube, the flange coacting with the walls of the tube to form a seal
to prevent air from reentering the tube. When the upper portion of
the cap is out of the tube, the tool is released, the lower portion
of the cap and the flange remaining in the tube to form a vacuum
seal.
The foregoing and other objects, features, and advantages of the
invention will be apparent from the following more particular
description of a preferred embodiment of the invention as
illustrated in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the sealing cap and insertion tool
of a preferred embodiment of the invention.
FIG. 2 is a cutaway side view along the line of a 2--2 of FIG. 1 of
a cap and a portion of the insertion tool of the preferred
embodiment of the invention.
FIG. 3 is a partially cutaway sideview showing the cap partially
mounted on the insertion tool.
FIG. 4 is a partially cutaway side view illustrating the cap fully
mounted on the tool and inserted in the test tube.
FIG. 5 is a partially cutaway side view illustrating the cap
sealing the tube with the insertion tool released.
FIG. 6 is a partially cutaway sideview illustrating the vacuumized
test tube with the cap mounted on a needle assembly and being
utilized for drawing a biological sample.
DETAILED DESCRIPTION
Referring now to the figures, it is seen that this invention
includes a test tube sealing cap 10 and a cap insertion tool 12.
The body of the cap is formed of an upper cylindrical portion 14
and a lower cylindrical portion 16 of enlarged diameter. Portion 14
has a bore 18 which terminates at one end in an enlarged
counterbore 20 in portion 16 and is sealed at the other end by the
top of the cap 22. The diameter of enlarged portion 16 of the cap
is slightly less than the diameter of test tube 24 with which the
cap is to be utilized.
A flexible flange ring 26 is formed as an integral part of and
projects from the lower end of enlarged portion 16. The lower
surface 28 of ring 26 is preferably ridged for reasons which will
be described shortly. An annular groove 30 is formed in portion 16
just above flange 26. As will be seen shortly, flange 26 may be
bent back into groove 30 when the cap is inserted in test tube
24.
A pair of webs 32 project from opposite sides of upper portion 14
of cap 10. As may be best seen in FIG. 2, the depth of the web is
greater at the bottom of the web than at the top. Similarly the
width of the web may also be greater at the bottom. Projecting from
the bottom of each web 32 is a cantilevered detent arm 34 at the
end of which is mounted a detent 36 having a triangular cross
section. Each detent 36 has a tapered leading edge 36 and a tapered
trailing edge 40.
Another feature of cap 10 is a ring-shaped groove 42 formed in the
upper surface of lower portion 16. An optional feature of cap 10 is
a rupturable seal 44 across the lower end of bore 18. An
anticoagulant or other substance may be sealed in bore 18 by seal
44. While cap 10 may be constructed of rubber, for reasons of cost
and ease of fabrication it is preferably formed of a plastic. Seal
44 may be formed of a suitable material such as an elastomer.
Tool 12 consists of a handle 46, a shank 48, and a head 50. Head 50
consists of a pair of cantilevered arms 52 which are spaced at
their ends by a distance slightly greater than the width of a web
32. Arms 52 may be formed by cutting a pair of grooves 54 in a
short cylindrical tube. A projection 56 having a triangular
cross-section with an angled leading edge 58 and an angled trailing
edge 60 is formed at each end of each arm 52 adjacent to slots 54.
The length of each arm 52 is slightly greater than the height of
upper portion 14 of cap 10.
Operation
In operation, a cap 10 is first fitted onto a tool 12. This is
accomplished by inserting the upper portion 14 of the cap into the
hollow center of the head 50 with webs 32 being positioned in
grooves 54. When the leading edges 58 of projections 56 come into
contact with the leading edges 38 of detents 36, angled edges 38
and 58 coact to cam projections 36 out of the way of projections
56. FIG. 3 illustrates the cap and the tool in this partially
assembled condition. As cap 10 is moved further into the head of
tool 12, projections 56 pass detents 36 and come to rest positioned
partially in groove 42. The natural resiliency of the plastic
material of arms 34 causes the arms 34 and detents 36 to return to
substantially their initial position once projections 56 have
passed. FIG. 4 illustrates the relative position of the cap and
tool when they are fully mated. When cap 10 is mounted onto tool
12, the attendant uses the tool to insert the cap into the mouth of
test tube 24 and to push the cap all the way to the bottom of the
tube. FIG. 4 illustrates the arrangement of the various elements
with cap 10 inserted all the way into tube 24. It is noted that
since flange ring 26 has a diameter greater than that of the test
tube, it is folded back to a position partially into groove 30 when
the cap is in the test tube. As the cap is inserted into the tube,
the pressure of the air trapped ahead of the cap presses against
flange 26 forcing flange 26 out of contact with the walls of tube
24 and further into groove 30. Since the diameter of the remainder
of cap 10 is slightly smaller than the diameter of the test tube,
air ahead of the cap is permitted to escape as the cap is inserted
into the tube. Thus with cap 10 all the way into the tube, as shown
in FIG. 4, there is virtually no air remaining in the portion of
the tube under the cap.
The next step in the operation is to withdraw cap 10 from the tube,
again, using tool 12 for this purpose. When a force is initially
applied to tool 12 in a direction to remove the tool from tube 24,
the tool moves relative to the cap until trailing edges 40 and 60
engage. Since these surfaces are both angled, the interaction of
the surfaces has a tendency to cam detent 36 out of the way of
projections 56. However, as seen in FIG. 4, the walls of tube 24
are in close proximity to arms 34 and detents 36, preventing them
from being cammed out to the positions shown in FIG. 3. Cap 10 is
thus held in tool 12 by the interaction of detent 36 with
projections 56, permitting the tool to be utilized to draw the cap
out of tube 24. As cap 10 is withdrawn from tube 24, the reduced
pressure remaining in the area of the tube under the cap draws
flange 26 down into the tube. This action is opposed by the walls
of tube 24. The pressure differential between the front and back of
flange 26 is thus effective at this time to force the flange
against the walls of the tube, providing a seal that prevents air
from leaking back into the area of the tube under the cap. Ridges
28 on the underside of flange 26 provide a larger contacting area
between the flange and the tube, improving the sealing action. A
substantial vacuum therefore remains in tube 24 in the portion
thereof under cap 10.
When cap 10 has been removed to the position shown in FIG. 5, with
its upper portion 14 out of tube 24, arms 34 and detents 36 are no
longer restrained by the walls of tube 24 and are cammed out to
permit the passage of projections 56. Cap 10 is thus, at this stage
of the operation, removed from tool 12. As detents 36 are cammed
out, they frictionally engage the upper edge of tube 24. This
frictional engagement holds the detents in the position shown in
FIG. 5, where they coact with the upper surface of the tube to
prevent the cap from being drawn back into the tube.
From the above it is apparent that a three-step operation has been
provided for vacuumizing a test tube. The operation may be
performed rapidly, normally in a matter of seconds, by a minimally
trained individual utilizing simple and inexpensive equipment.
FIG. 6 illustrates a vacuumized test tube 24 sealed with a cap 10
as it is utilized for drawing a biological sample. For this
operation, one end of a hollow needle 64 is inserted into, for
example, a vein of the individual from whom a biological sample is
to be drawn. Needle 64 is mounted and sealed in a cup-shaped holder
66 which may, for example, be constructed of glass or a plastic
material. The capped end of tube 24 is inserted into holder 66 to a
position where the other end of needle 64 pierces end 22 of cap 10.
When this occurs, the pressure differential between, for example,
the vein at one end of needle 64 and the vacuum at the other end of
needle 64 causes the blood or other biological sample to flow
through needle 64 into tube 24. Fluid continues to flow through
needle 64 until the pressure at its two ends has been equalized. If
the tube has been properly evacuated, this will occur when tube 24
has been substantially filled. When tube 24 is full, needle 64 is
removed from the individual and tube 24, with cap 10 still in
place, removed from the holder and needle assembly. The hole made
in cap 10 by needle 64 will normally seal adequately to permit the
sample to be stored and shipped in the tube.
If there is a substance to be mixed with the sample stored in bore
18 behind seal 44, the increased pressure differential across seal
44 when needle 64 pierces the cap will rupture the seal, permitting
the substance and the sample to flow together into tube 24. Since
the sample flows through the substance on entering the tube, and
the two elements enter the tube together, a good mixing action is
effected, eliminating the need for subsequent shaking by the
attendant. Should a seal 44 be required which is strong enough so
as not to be rupturable by the pressure differential created when
the needle enters cap 10, the length of bore 18 and of the needle
may be selected so that the needle penetrates seal 44 causing it to
rupture.
While in the description above, it has been assumed that the tube
24 is empty when it is vacuumized, it is apparent that a culture or
other substance to be stored in vacuum could be in the tube at that
time. Further, while a particular detent mechanism 36 and means for
mounting it has been shown, it is apparent that all that is
required is that a detent mechanism be provided which may be cammed
out of the way of a suitably designed insertion tool when the upper
portion of the cap body is out of the tube but is restrained from
being cammed when the upper portion of the cap is in the tube.
Thus, while the invention has been particularly shown and described
above with reference to a preferred embodiment thereof, it will be
apparent to those skilled in the art that the foregoing and other
changes in form and details may be made therein by those skilled in
the art without departing from the spirit and scope of the
invention.
* * * * *