Note: Descriptions are shown in the official language in which they were submitted.
~3:~2~
TITLE OF T~IE INVENTION
Tube Assembly wlth a Breakaway Plug
ACKGROUND OF_THE INVENTION
Field of the Invention
This invention relates -to a tube assembly with a
breakaway plug. More particularly, it relates to a tube
assembly having a breakaway plug which is unlikely to be
ruptured or contaminated before use.
Discussion of Prior Art
Referring to FIG. 5b, there is illustrated one prior
art tube assembly. A Y-shaped branch tube 30 illustrated
in FIG. Sb comprises a main tube 31 and a branch tube 32.
The main tube 31 has two openings, that is, a proximal
opening 31a to be connected to a venipuncture needle ~not
shown) for blood collection, and a distal opening 31b to
be connected to a tubing 33b which is further connected to
a blood bag (not shown~. The branch tube 32 has a distal
opening 32b which has a blood-returning assembly mounted
thereon.
The component constituting the blood-returning
assembly are shown together with the branch tube 30 in
FIG. 5a in an exploded state. The blood returning
assembly comprises a sleeve 34 mounted on the distal
opening 32b, connector 35 fitted in the sleeve 34,
caulking member 36 to fluid-tightly join the sleeve 34 and
the connector 35, and a rubber cap 37 fitted on the
connector 37. The blood returning assembly is enclosed in
an envelope 38 for preventing contamination~ The envelope
33 has a peeling line 39 for ease of opening the envelope
38.
Upon returning blood corpuscles, the envelope 38 is
opened at the peeling line 39, and the cap 37 is then
removed for connecting another member to the connector 35.
i~,
` ` ~3~
The blood returning assembly as descri'oed above has a
plurality of drawbacks as described below~
(1) Since the blood returning assembly comprises a
number of components, the number of joints are also
increased resulting in an increased risk of contamination.
Efficiency in course of assembly is also :Lowered.
(2) Since the medical solution in the blood bag
directly contacts the rubber cap via tubings, amount of
the substances eIuted from the rubber cap is increased
although the amount is below the standard value.
(3) The rubber cap may be loosened, or even come off
in an extreme case, due to an increased inner pressure of
the blood bag during an autoclave sterilization of the
system.
(4) The blood returning assembly is wrapped with the
envelope by way of precaution against the contamination in
(3). Upon returning the blood corpuscles, a troublesome
step of opening the envelope is required before taking the
rubber cap off. ~omplicated operation increases the risk
of contamination and lowers the operation efficiency.
SUMMARY OF T~E INVENTION
An object of the present invention is to provide a
tube assembly having a breakaway plug which is not likely
to be accidentally ruptured or contaminated during
manufacture or transportation, but can be readily torn off
upon use.
According to the present invention, there is
provided a tube assembly comprising
a tubular body having at least two open ends,
a plug of a relatively flexible material mounted on
one open end of said tubular body, the plug including (a)
a hollow mount segment having an open end, a portion of
the mount segment extending from its open end being
fixedly secured to the one open end oE the tubular body,
~ 3 ~
(b) a closing segment axially connected to the mount
segment, and (c~ a frangible portion located axially
outside the secured portion whereby the plug is breakable
at the frangible portion and removable from the one open
end of the tubular body, and
a protector of a relatively rigid material fitted
over the plug.
In one preferred embodiment, the mount segment
includes a first wall portion with a relatively smaller
inner diameter extending from the open end of the mount
segment and a second wall portion with a relatively larger
inner diameter extending from the first wall portion to
the closing segment. The first wall portion is secured to
the one open end of the tubular body and the frangible
portion is a circumferential notch in the outer surface of
the second wall portion.
The protector is in close fit on the closing segment
of the plug, but extends over the frangible portion with a
spacing from the mount segment. The protector has such a
hardness that it may not prevent breakage of the plug at
the frangible portion.
The open end of the tubular body axially extends
beyond the frangible portion of the plug toward the
closing segment of the plug.
The closing segment of the plug has a non-circular
cross section in a direction transvearse to an axial
direction.
BRIE _DESCRIPTION OF THE DRAWING_
The above and other objects, features, and
advantages of the invention will be better understood by
reading the following description taken in conjunction
with the accompanying drawings, in which:
FIG~ 1 is a partially cross-sectional plane view of
a tube assembly with a brea~away plug according to one
embodiment of the present invention;
FIG. 2a is an exploded cross~sectional view of the
tube assembly of the present invention showing a tube
branch, a plug and a pro-tector in a disassembled state;
FIG. 2b is a cross-sec-tional view of the tube
assembly showing a tube branchl a plug and a protector in
an assembled state;
FIG. 3a and 3b are cross-sectional views oE the plug
taken along lines A-A and B-B in FIG. 2a, respectively;
FIG. 4a and 4b illustrate a plasmapheresis system
having the tube assembly o the invention incorporated
therein;
FIG. 5a is an exploded view of a prior art tube
assembly; and
FIG. 5b is a front view of the prior art tube
assembly in an assembled state.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The tube assembly of the present invention includes
a tube body having at least two open ends. Any tubular
body having at least two open ends between which a flow
path extends may be employed. Although a commonly used
four-way branch tube is referred to as a typical examp:Le
in the following description, ~he present invention is not
limited to the four-way branch tube.
FIG. 1 illustrates a four-way branch tube as one
embodiment of the tube assembly of the present invention.
It will be understood that FIG. 1 is an enlarged view
corresponding to a circled portion in the system of FIG.
4a. The four-way branch tube illustrated in FIG. 1 has
four openings, that is, a first opening 11 to be connected
to a puncture needle 24 for blood collection, a second
opening 12 to be connected to a first blood bag 20, a
11 3~2~
third opening 13 to be connected to a second blood bag 21,
and a fourth opening 14 having a plug 2 mounted thereon
(see FIG. 4a). For brevity of description, a flow path
communicating between the first and second openings 11 and
13 is designated a main flow path. With respect to the
main flow path the first opening 11 to be connected to
the needle 24 is designated a proximal end and the second,
third and fourth openings 12, 13 and 14 are designated
distal ends.
The feature of the present invention resides in a
combination of the branch 4 having the fourth opening 14,
the plug 2 mounted on the branch 4, and a protector 30
mounted on the plug. The components are described in
detail in FIG. 2a, which is a cross-sectional view of the
branch 4, the plug 2, and the protector 30 in an exploded
state. A full assembly of these components is shown in
FIG. 2b although the illustrated components are modified
ones.
The branch 4 of the four-way branch tube has a flow
path-defining bore 14 terminating at an open end 6 and
includes a stepped wall portion 5 having a smaller outside
diameter than the remaining. The outside wall of the
branch is stepped to form the smaller outside diameter
wall portion 5 for mounting the plug 2 thereon.
The plug 2 includes a hollow mount segment providing
an open end 7 at one end and a closing segment axially
connected to the mount segment and providing a closing end
8 at another end. The hollow mount segment includes a
first wall portion 9 with a relatively smaller inner
diameter extending a predetermined distance from the open
end 7 and a second wall portion 10 with a relatively
larger inner diameter ex-tending from the first wall
portion 9 to the closing segment. The first wall portion
9 is fixedly secured -to the stepped wall portion 5 of the
branch 4 as shown in FIG. 2b. The second wall portion 10
~L3~2~
i5 provided with a frangible portion in the form of a
circumferential notch 15 in the outer surface whereby the
plug is breakable at the frangible portion and removable
from the branch~ The closing segment may be ei-ther a
solid segment as shown in FIG. 2a or a hollow segment as
shown in FIG. 2b as long as it provides a closlng end to
the bore of the hollow mount segment.
The plug pre-Ferably has a cross sectional shape
other than a circle on a distal side with respect to the
frangible portion 15, the cross section being taken in a
direction perpendicular to the longitudinal axis of the
plug. FIGS. 3a and 3b are cross sections taken along
lines A-A and B-B in FIG. 2a, respectively. More
particularly, the first wall portion 9 of the plug 2 with
a relative smaller inner diameter which is to be secured
to the stepped wall portion 5 of the branch ~ has
substantially a true circular cross section having an
inner diameter substantially equal to the outer diameter
of the stepped wall portion 5 as shown in FIG. 3a. The
remaining portion of the plug 2, preferably the closing
segment has a non-circular cross section. For example,
the closing segment has a square cross section as shown in
FIG. 3b. Since the closing segment is a distal segment of
the plug which not only closes the bore in the hollow
mount segment, but also serves as a handle or lever upon
breaking the plug at the frangible portion, the closing
segment may have a rectangular, ellipsoidal or other cross
section which is convenient to manually grip. Also
preferably, the closing segment is an axially elongated
segment as shown in FIG. 2b for the same reason.
The tube assembly 1 of the present invention also
includes the protector 30 fitted over the plug 2. The
protector 30 is in close fit with the outside of the plug
2 for protecting the plug. In the example of FIG. 2a, the
protector 30 is a block which defines therein a cavity
~L~123~
having an open end and a closed end. An inside portion of
the cavity mates with the closing segment of the plug 2.
A protector of a modified shape is shown in FIG. 2b. The
shape of the protector 30 is not limited to those shown in
FIGS. 2a and Zb and the protector may be a tubular s]eeve
ha~ing a portion to be tightly engaged over the closing
segment of the plug 2. The protector 30 functions as an
ordinary protector for the plug when the branch is not on
use, and as a grip when the plug must be broken to render
the branch ready for use.
In order that the plug 2 be readily torn off by
gripping and twisting the protector 30, the protector 30
preferably has a non-circular outer configuration such as
a rectangular, square and elli~psoidal shape.
FIG. 2b shows the components in an assembled state.
The plug 2 is mounted on the branch 4 to close its opening
14 and also covered with the protector 30. The first wall
portion 9 of the plug is in snug fit over the stepped wall
portion 5 of the branch. A space 3 is left between the
second wall portion 10 of the plug and the stepped wall
portion 5 of the branch in a radial direction. The space
3 is sufficient to keep the open end 6 of the branch 4
from obstructing in breaking the plug 2 at the frangible
portion 15. For the same reason, the distal or open end 6
of the branch ~ is axially spaced apart from the plug 2.
The protector 30 must be in snug fit over the plug 2
in order to protect the plug 2 from any accidental
external force and to prevent any sliding motion between
the protector and the plug when the protector 30 is
twisted with a finger grip to tear off the plug 2. The
protector is in close fit on the closing segment of the
plug 2, but axially extends over the frangible portion 15
with a spacing from the mount segment. A space is left
between the inside wall of the protector 30 and the
outside wall of the plug 2 at least in a region axially
~31~2~3
located on the proximal side with respect to the frangible
portion 15. In the embodirnent shown in FIG. 2h, a space
is left between the protector 30 and the mount segment of
the plug 2 and the protector 30 is in tight engagement
with the closing segment of the plug 2. The space between
the inside wall of the protector 30 and the outside wall
of the plug 2 bridging over the frangible portion 15 is
effective in facilitating separation of -the plug 2 by
tearing it off.
The fourth opening 14 is closed with the plug 2
covered with the protector 30 when the corresponding
branch 4 is not in use. When it is desired to connect
another member to the fourth opening 14, the plug 2 is
removed from the opening by tearing or twisting off the
plug 2 at the frangible portion 15. The branch 4 with its
flow path open is now ready for connection to another
mem~er.
In the preferred embodiment shown in FIG. 2b, the
open end 6 of the branch axially extends beyond the
frangible portion 15 of the plug 2 toward the closlng
segment of the plug. After the plug 2 is removed by
gripping the protector 30 and turning the protector so as
to tear off the plug 2 at the frangible portion 15, the
open end 6 of the branch 4 protrudes beyond the remainder
of the plug mount segment left attached to the branch 4.
When it is desired to conn~ct another connecting member,
for example, a tube having a puncture needle, to the open
end 6 of the branch 4, the open end 6 is exposed beyond
the plug residue and thus clearly visible to ensure safe
connection. There is little likelihood that the other
connecting member be inadvertently contac-ted to the cut
edge of the plug 2 which would be sometimes contaminated,
thus avoiding contamination of the flow path.
The frangible portion 15 may be formed at any
location between the open end 7 and the closed end 8 of
~3~2~
-the plug. Preferably, the frangible portion 15 is
provided in the outside wall of the second or larger inner
diameter wall portion 10 of the mount segment of the plug
2. Location of the frangible portion 15 in the second
wall portion 10 means tha-t the frangible portion 15 is
located radially outside the space 3 between the plug 2
and the branch 4. Then it is very easy to tear off the
plug 2 by twisting even though the plug is made of a
relatively flexible material.
The engagement between the plug 2 and the protector
30 is not particularly limited as long as it ensures
cliping-off of the plug by grasping the protector 30 with
fingers and ~urning it with the plug 2 so as to tear off
the plug without any sliding motion between the protector
and the plug.
In general, medical tubings are made of
polycarbonate and flexible vinyl chloride resin. When a
plug is secured to such a tube; it is desired not to use
an adhesive at the connection between the plug and the
tube in order to avoid contamination to fluid to be passed
therethrough, typically blood. If a tube a~d a plug are
made o similar types of material, a blocking bond can be
achieved between them by utilizing the heat applied for
autoclave sterilization. Since the plug is formed of a
relatively flexible material such as polyvinyl chloride
resin, it is difficult to tear off the plug with a click
by twisting because the plug as a whole is softly twisted.
The protector 30 is made of a relatively rigid material in
order to facilitate breakage of the plug 2. A choice of
the material of the protector 30 is made such that the
protector may not be bonded to the branch and the plug
through blocking under the influence of the heat applied
during autoclave steriliæation. A typical examples of the
relatively rigid material is a polypropylene resin. A
preferred combination of materials meeting the above
~1 3~2 3~
1 0
requirement is a combination of polycarbonate for the
branch 4 or tubular body, polyvinyl chloride for the plug
2 and polypropylene for the protector 30O Another
preferred combination of materials for the tubular body,
plug and protector will occur to those skilled in the art
in light of the above teachings.
Operation
The operation of the four-way branch tube having a
plug mounted on one branch as shown in ~IG. 1 is described
by referring to a system for plasmapheresis therapy having
the branch tube incorproated therein.
As shown in FIG. 4a, the plasmapheresis system
includes four sections of tubing connected to the four-way
branch tube 1. A first section of tubing extends from a
puncture needle 24 placed in the vein of a donor 23 to the
first opening 11 of the branch tube for the purpose of
blood collection and has a hemostat 28 thereon. A second
section of tubing extends from the second opening 12 of
the branch tube to a first blood bag 20 and has a hemostat
29 thereon. A third section of tubing extends from the
third opening 13 of the branch tube to a second blood bag
21 via a closure member in the form of a click tip 19. A
fourth section of tubing extends from the fourth opening
14 of the branch tube to a Y set 22. The fourth section
of tubing is a trunk line of the Y set which includes a
first inIet line extending to a physiological saline
bottle 27 through a clamp 16 and a second inlet line
having a clamp 17. This is an outline of the system, and
all the lines are not connected at the same time.
Connection will become apparent from the following
description of operation.
While clamps 16, 17 and 18 on the lines associated
with the Y set 22 are closed, a needle connected to the
line with clamp 16 is punctured into the saline bottle 27.
Then the clamp 16 is opened and the clamp 18 is released
~3~3:~
to fill the Y set with saline. The clamp 1~ is again
closed.
During this operation, the plug 2 on the branch 4 of
the four~way branch tube is kept normal or unbroken and
covered with the protector 30. There is no possibility
that the plug is accidentally ruptured to allow
contamination of the opening of the branch 4 during
manufacture and setting of the branch tube 1. The first
opening 11 of the branch tube 1 is in fluid communication
with the needle 24, and the second opening 12 in fluid
communication with the first blood bag 20. The third
opening is connected to the second blood bag 21 although
the click tip 19 is also kept normal or unbroken so that
the flow path to the second blood bag 21 is closed.
The next step is to connect a connector at the free
end of the Y set trunk to the branch 4 of the branch tube.
The hemostat 29 is fastened on the second section of
tubing connected to the first blood bag 20 in order to
prevent reverse flow of medical liquid in the first blood
bag 20. Then the plug 2 is torn off at the frangible
portion 15 to open the associated branch 4 by manually
grasping and twisting the protector 30.
If the plug 2 without the protector 30 is manually
twisted, the plug of flexible material tends to be easil~
deformed and is thus difficult to tear off in a click
manner. In contrast, the plug 2 is received in the
protector 30 of rigid material such as polypropylene
according to the present invention. When the protector 30
is gripped and twisted, the protector in tight engagement
over the plug 2 prevents deformation of the plug and
assists in tearing off the plug at the frangible portion.
In the preferred embodiment, the open end 6 oE the
branch 4 extends beyond the frangible portion 15 of the
plug 2. After the plug 2 is torn off at the frangible
portion 15 by manually twisting the protector 30 along
~ 3 ~ 2 ~ ~ ~
with the plug 2, the open end 6 is exposed and protrudes
beyond the torn edge of the plug 2. Then the connector of
the Y set 22 is connected to the protruding open end 6 of
-the branch 4. At this point, the open end 6 of the branch
4 is protruding and visible, connecting operation is very
easy and accurate. Contamination is avoided because the
connector can be attached to the open end 6 without
inadvertent contact with any probably contaminated member.
The next step is to collect blood from the donor 23.
The first section of tubing is fastened by the hemostat 28
at a location near the needle 24. The puncture needle is
inserted into the vein of the donor 23. After entry of
blood into the blood collecting tube is observed, the
hemosta-ts 28 and 29 are taken off to communicate an open
continuous flow path to the first blood bag 20~
Since the flow path to the second blood bag 21 is
closed by the click tip 19 at this point, blood flows
under gravity from the needle 24 to the first blood bag
20. Blood collection is continued until the first blood
bag 20 is filled with a predetermined volume of blood.
Then the section of tubing to the first blood bag 20 is
sealed with a tube sealer or a pair of aluminum rings (not
shown) and cut therebetween to separate the first blood
bag 20.
The whole blood in the first blood bag now removed is
subjected to centrifugal separation. During the step,
saline is transfused dropwise from the bottle 27 to the
donor through the Y set 22, the branch 4 with the plug
broken, and the needle 24 as shown in FIG. 4b.
The platelet and red cell concentrates thus separated
are independently return transfused to the donor 23. More
particularly, an outlet 25 of the first blood bag 20 is
connected to the second inlet tube of the Y set 22 having
the clamp l7. I'hen the concentrates are returnecl to the
~L 3 ~
donor 23 through the Y set 22, the four-way branch tube 1,
and the needle ~4.
At the end of return transfusion, the branch tube 1
is held in one hand, and the click tip 19 is manually torn
off to open the flow path to the second blood bag 21.
Blood is again collected from the donor 23 to the second
blood bag 21 through the needle 2~ which has been placed
in the vein of the donor. Likewise the first blood bag
20, the blood collected in the second blood bag 21 is
centrifugally separated and transfused back to the donor.
In the tube assembly oE the present invention, a plug
is mounted on one open end of a tubular body or one branch
of a branch tube to close the flow path thereof, but
breakable and removable from the tubular body to open the
flow path. The plug is accommodated in a protector which
has a cavity of a shape mating with the plug
configuration. The tube assembly has the following
benefits.
1) The plug is protected from any external force applied
during manufacture and transportation. Just unitl the
associated tubular body or branch is on use, there is
little possibility that the plug is accidentally ruptured
to cause contamination of the flow path of the tubular
body.
2) The open end of the tubular body or branch closed
with the plug can be opened with the protector fitted over
the plug, eliminating the risk of contamination of the
open end which is detrimental when the branch is used as a
cell return inlet.
3) Since the protector is fitt~d over the plug, the area
available for gripping is increased as compared with the
plug without the protector, facilitating tearing-off
operation to open the flow path.
~2~ ~
1 4
4) In the embodiment wherein the open end of the tubular
body or branch extends beyond the frangible portion in the
plug toward the closing end thereo-f, another member can be
readily connected to the open end after the plug is torn
off a-t the frangible portion, avoiding the risk of
contaminating the flow path of the branch.
5) In the embodiment wherein the frangible portion is
-Eormed in the outside wall of the second wall portion of
the plug having a relatively larger inner diameter, it is
easy to tear off the plug at the frangible portion even
though the plug is made of flexible material.
6) In the embodiment wherein the closing segment of the
plug and the corresponding portion of the protector have a
non-circular cross section, the protector is easy to grip
for breakage.
