U.S. patent number 3,864,979 [Application Number 05/346,423] was granted by the patent office on 1975-02-11 for blood sedimentation tube barrier.
This patent grant is currently assigned to Becton, Dickinson and Company. Invention is credited to Waldemar A. Ayres.
United States Patent |
3,864,979 |
Ayres |
February 11, 1975 |
Blood sedimentation tube barrier
Abstract
A liquid collection tube, such as a blood sedimentation tube,
has, within, a barrier plug which permits air to pass therethrough
but prevents the passage of liquid beyond the bottom of the barrier
plug. The barrier plug has a resilient non-porous outer portion
which engages the walls of the tube and a central porous core which
is formed of a plurality of vertical adjacent filaments.
Inventors: |
Ayres; Waldemar A. (Rutherford,
NJ) |
Assignee: |
Becton, Dickinson and Company
(East Rutherford, NJ)
|
Family
ID: |
23359314 |
Appl.
No.: |
05/346,423 |
Filed: |
March 30, 1973 |
Current U.S.
Class: |
73/864.02;
422/513; 422/922; 96/219; 73/864.03 |
Current CPC
Class: |
B01L
3/0213 (20130101); B01L 3/021 (20130101); G01N
2035/1023 (20130101); B01L 2200/141 (20130101); B01L
2200/085 (20130101) |
Current International
Class: |
B01L
3/02 (20060101); B01l 003/02 () |
Field of
Search: |
;23/259,292 ;55/159
;73/425.4P |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wolk; Morris O.
Assistant Examiner: Marantz; Sidney
Attorney, Agent or Firm: Kane, Dalsimer, Kane, Sullivan and
Kurucz
Claims
I claim:
1. A liquid collection tube comprising; a hollow transparent tube
open at the top and bottom, a barrier plug mounted in the tube
intermediate the open ends thereof, the plug having a porous
portion and being mounted in the tube at a predetermined location
so that when the bottom open end is placed in liquid to be
collected and suction is applied to the top open end, the porous
portion of the plug will permit air to pass therethrough and draw
liquid into the tube up to the bottom of the barrier plug and not
through the porous portion, thereby automatically stopping the
height of the liquid column entering the tube and preventing liquid
from progressing above the barrier plug, the barrier plug being
cylindrical in configuration with a non-porous portion forming an
outer part of the plug and the porous portion forming a central
core concentric with the non-porous portion of the plug whereby the
non-porous portion engages the side walls of the tube, and the
porous portion being formed of a plurality of vertical adjacent
filaments and the non-porous portion being of a resilient
material.
2. The invention in accordance with claim 1 wherein the liquid
containing tube is a blood sedimentation tube
3. The invention in accordance with claim 1 wherein the filament
material is wool fibers and the resilient nonporous material is a
white elastomer.
4. The invention in accordance with claim 1 wherein the filaments
are plastic monofilaments.
5. A barrier plug adapted to be mounted in a hollow tube with open
top and bottom ends comprising; a body at least partially porous
and being adapted to be mounted at a predetermined location and in
sealing engagement with the inner walls of the hollow tube, whereby
when the bottom open end is placed in liquid to be collected and
suction is applied to the top open end on the tube, the porous
portion of the plug will permit air to pass therethrough and draw
liquid into the tube up to the bottom of the barrier plug and not
through the porous portion thereby automatically controlling the
amount of liquid entering the tube and preventing liquid from
progressing above the barrier plug, the plug including an outer
cylindrical concentric non-porous portion and an inner porous core
portion concentric with the outer portion to form a cylindrical
plug, the non-porous portion being made of resilient material and
the porous portion being made of a plurality of vertical filaments
adjacent to one another and positioned within the non-porous
portion to form a core therein.
6. The invention in accordance with claim 1 wherein the filaments
are plastic monofilaments.
7. The invention in accordance with claim 1 wherein the filaments
are wool fibers and the non-porous portion is of white resilient
material.
Description
BACKGROUND OF THE INVENTION
In working with blood, it is important to prevent the accidental
sucking of blood up into the operator's mouth during use of the
sedimentation tube. The blood may be diseased as with hepatitis,
syphilis, etc., or otherwise obnoxious.
Another factor to be kept in mind in working with collection tubes
is that some structure for positively providing a stop means to
accurately control the height of the blood column easily and
efficiently is desirable. In working with blood sedimentation
tubes, the operator has to carefully control the amount of liquid
being drawn into the tube. This requires periodic checking of tube
levels. Automatic stop means for controlling the filling of a tube
such as a blood sedimentation tube when the blood level has reached
a predetermined column height would be a great improvement and a
convenience over previously known procedures.
A third concern in blood sedimentation tube operations is the
retention of the fluid of the proper column height in the tube
during sedimentation, usually of one hour duration. Consequently,
if the structure of the tube itself includes means for assisting
the retention of the fluid in the tube, it would also be a great
improvement and convenience over procedures presently known in the
field.
SUMMARY OF THE INVENTION
With the above discussed background in mind, it is among the
primary objectives of the present invention to provide a barrier
means for use in a blood sedimentation tube which barrier may be
positioned at a desired point along the tube length within the tube
to exactly control the height of the liquid column to be drawn into
the tube. The barrier also permits air to pass through so that
fluid can be drawn into the tube but will not permit any of the
fluid to pass through, thereby, alleviating danger of fluid flowing
into the operator's mouth. Furthermore, the barrier means
facilitates the retention of the fluid below it within the tube
after the collection procedure has been accomplished without the
necessity of additional means such as holding one finger on the top
of the tube during transference of the liquid from the collection
site to a test site.
In summary, a liquid collection tube barrier is provided for a
hollow tube open at the top and bottom. The barrier is in the form
of a plug mounted in the tube intermediate the open ends. The plug
has a porous portion. When the bottom open end is placed in liquid
to be collected and suction is applied to the top open end, the
porous portion of the plug permits air to pass therethrough and
draws liquid into the tube up to the bottom of the barrier plug and
not through the porous portion. In this manner, the height of the
liquid column within the tube is automatically controlled and
stopped at a predetermined location to prevent liquid from
progressing above the barrier plug.
With the above objectives, among other, in mind, reference is had
to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a diagrammatic view of the liquid collection tube barrier
of the invention mounted in a blood sedimentation tube being filled
with blood;
FIG. 2 is a fragmentary sectional view of the portion of the tube
containing the barrier plug of the invention; and
FIG. 3 is a fragmentary enlarged top sectional view thereof taken
along the plane of line 3--3 of FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1, 2 and 3 of the drawing show the barrier plug 20 mounted in
the passageway of a collection tube 21. For descriptive purposes,
the type of tube in which the barrier plug is employed is a blood
sedimentation tube of a conventional type. As shown in FIG. 1, the
blood sedimentation tube 21 has an open top end 22 through which an
operator applies suction. The opposite or bottom end 24 is also
open and is applied to the source of fluid such as blood in a
conventional container 23. A continuous passageway 25 extends from
tip 24 to tip 22 of the tube. Mounted in passageway 25 is the
barrier plug 20 at a predetermined location. The location of plug
20 is determined by the height of the column of blood to be
collected. An appropriate scale is applied to the outer face of the
tube and the bottom of the plug would be positioned at, for
example, the zero mark with other calibration marks below at
intervals showing the amount of sedimentation in millimeters per
unit time, such as in one hour.
Turning to consideration of plug 20 in detail, it is generally
cylindrical in configuration having an outer portion 26 which is
non-porous in nature and an inner portion or core 27 which is
porous in nature. As shown in FIG. 2, portions 26 and 27 are
generally concentric, with the core portion 27 being surrounded by
the non-porous outer portion 26. Portion 26 engages a sealing
relationship with the inner wall of tube 21. Portion 26 will permit
the passage of neither air nor liquid while porous portion 27 will
permit the passage of air but not liquid.
In regard to materials which can be utilized in the system, tube 21
can be of low cost glass or plastic and is generally transparent to
permit viewing of the liquid as it is collected within the tube. A
conventional column height scale can then be applied to the
exterior surface of tube 21 to accurately measure how far (usually
expressed in millimeters) the red cells settle during the test
period (usually 1 hour).
In regard to plug 20, the non-porous portion can be of a material
such as rubber, preferably white rubber, which is of a resilient
nature and which will not permit passage of air or liquid
therethrough. Additionally, the material is sealable with the inner
wall of the tube and will engage and hold the core portion 27 of
the plug in fixed position.
The core portion is constructed of a plurality of vertical adjacent
filaments 28. The tiny filaments 28 will permit passage of air
therebetween when suction is applied at the upper open end of the
tube but will not pass liquid therethrough, so that when liquid
reaches the bottom edge of the core group of filaments 28 it will
automatically stop at that point. The resilient nature of
non-porous portion 28 will maintain a tight inter-engagement with
the filaments and retain them in closely related fixed
position.
The filaments may be of a material such as wool fibers or any
similar operative structure such as plastic monofilaments or nylon
monofilaments.
In operation, in respect to the above discussed embodiment, tube 21
is manufactured with plug 20 at a predetermined point along its
length so that only a precise column height of liquid can be
collected therein. The bottom end 24 of the tube is then positioned
at the source of blood and suction is applied to the open end 22 of
the tube as shown in FIG. 1. Air will then be drawn through plug 20
and through the tube into the mouth and will draw blood 24 into the
tube until it reaches the bottom surface of plug 20 at which time
it will automatically stop. Therefore, the operator need not be
concerned with the blood column height during collection nor need
he be concerned about blood passing plug 20 and entering his mouth.
The next step is to transfer the tube of blood to the location
where it is to be tested or handled in some other manner. Another
feature of the present system assists in this transportation
action. The presence of plug 20 eliminates the necessity of
retaining a finger on the open end 22 of the tube during
transportation in order to prevent leakage from open end 24. This
is an advantage over open systems where a finger must be retained
over open end 22 to prevent blood leaking from the tube during
transportation.
The action of the embodiment of plug 20 is based on much greater
viscosity of blood than air. The viscosity of blood is
approximately 0.010019 poise (at 20.degree. C.). In contrast, the
viscosity of air is approximately 0.000182 poise (at 18.degree.
C.). These figures show that the viscosity of blood is more than
fifty times the viscosity of air. Therefore, it is much easier to
suck air up through the openings between the filaments than to suck
blood up between them. Furthermore, when the blood level rises to
the small apertures between the filaments, it is quite easy to feel
the difference in resistance to flow and to stop sucking. This is
what is meant when it is stated that the air will go through the
automatic stop barrier 20 but that blood will not. If forced, the
greater increased resistance to flow when the blood reaches the
barrier can be overridden, but with a little practice, it is very
easy for the operator to suck at such a rate that the blood inflow
stops automatically when the automatic stop barrier is reached. The
operator can even feel the impact of the rising blood column
hitting the barrier, and then stop sucking.
Tests have shown that even if some blood is sucked up into the
barrier or even above it, the red cells of this blood are
immobilized and will not adversely affect the sedimentation rate of
the blood in the open column below the blood barrier.
By using a somewhat more porous barrier memeber, the above
discussed capabilities of the present invention can be combined
with the ability to dispense liquid downwardly under better than
ordinary control when the index finger is lifted from the top of
the tube, allowing air to enter.
Most of the previous discussion of the invention has been devoted
to describing the application of the principles of the invention to
blood sedimentation rate analysis. This application has been for
the purposes of illustration and must not be construed as being
limiting. Applications to pipetting in general are also within the
scope of the invention. For example, in blood sedimentation rate
testing it is stated by the medical authorities the height of the
blood column is very significant but that the cross-section of the
blood column can be varied within rather wide limits without
adversely affecting the test results. Hence the sedimentation tubes
are usually calibrated in millimeters of height and not in relation
to volumetric capacity. This means that less expensive transparent
tubing can be used because the cross section of the bore does not
have to be closely controlled. Hence the term "column height" has
been used in this patent in connection with tubes for sedimentation
rate.
However, where it is desired to apply the principles of this
invention to pipettes, then calibrations would be in terms of
"volumetric capacity".
In addition to the handling of blood, increased safety in
preventing other dangerous liquids from entering the mouth is
achieved by the present invention. Also pipetting is facilitated in
the provision of easy and accurate filling of the pipette relative
to its scale, plus improved control in dispensing aliquots or other
partial amounts, where the more porous type of barrier member is
used than with blood sedimentation tests.
Thus, the above discussed objectives, among others, are effectively
attained.
* * * * *