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BACKGROUND OF THE INVENTION
The present invention relates to catheters.
A various assortment of catheters, such as urinary catheters and
endotracheal tubes, have been proposed for use in patients. In the case of
urinary catheters, Foley catheters are commonly constructed with a shaft
having a drainage lumen and an inflatable balloon adjacent a distal end of
the shaft. During placement, a distal end of the catheter is passed
through the patient's urethra until the balloon and drainage eyes, which
communicate with the drainage lumen, are located in the patient's bladder,
and the balloon is inflated through an inflation lumen to retain the
catheter in place. During catheterization, urine drains through the
drainage eyes and lumen and through a drainage tube connected to a
proximal end of the catheter to a drainage bag for collection therein.
Conventional catheters of this sort were made from latex rubber through
dipping techniques known to the art. In time, it was discovered that the
latex catheters were not completely satisfactory since layers of the
dipped material occasionally became delaminated during use, thus causing
blockage in the inflation lumen and obstructing deflation of the balloon
when it was necessary to remove the catheter from the patient. As a
result, it became desirable to construct the catheter shaft from a
material which may be extruded in order to prevent possible blockage of
the inflation lumen, and reduce the cost of the catheter to the patient
due to simplified manufacturing techniques.
In turn, the materials which appeared satisfactory for use as a shaft posed
new problems in construction of the catheter. For example, it became
necessary to find suitable materials for the balloon which are
sufficiently elastic to permit inflation during use, and which are
compatible with the selected shaft for bonding purposes. Frequently,
materials which appeared otherwise satisfactory for the catheter shaft and
balloon proved to be incompatible when attempts were made to bond the
balloon to the shaft through use of adhesive or sealing. In addition, it
became necessary to secure a tip to the distal end of the extruded shaft,
and a connector to the proximal end of the shaft. Such tips and connecters
have been formed separately, and have been adhered to the shaft. However,
in the case of the connecters, it is necessary to establish communication
between lumens in the connecter and the associated inflation and drainage
lumens in the shaft. In the case of the tips, it is necessary to obtain a
sufficient bond of the tip to the distal end of the shaft while closing
the distal end of the inflation lumen. In both cases, difficulties have
been encountered in obtaining the proper alignment of lumens and achieving
the desired bond. In addition, it has been necessary in the past to
separately form an opening in the outer surface of the shaft to obtain
communication between the inflation lumen and a cavity beneath the
balloon. All of the excessive operations and difficulties associated with
construction of the catheter deleteriously affect the capability of
providing the catheter, which is considered a disposable item, at a
significantly reduced cost.
SUMMARY OF THE INVENTION
A principal feature of the present invention is the provision of a catheter
of simplified construction and reduced cost.
The catheter of the present invention comprises, an elongated shaft having
a main lumen extending through the shaft, and an inflation lumen extending
through a wall of the shaft. The catheter has a tip molded directly onto a
distal end of the shaft, with the tip having a lumen communicating with
the main lumen of the shaft, and at least one opening adjacent a distal
end of the tip communicating with the tip lumen. The molded tip defines a
distal end portion of the inflation lumen and an aperture at an outer
surface of the tip. The distal end of the shaft and the proximal end of
the tip have complementary beveled portions defining juncture surfaces
which are bonded together. The catheter has a connecter directly bonded
onto a proximal end of the shaft, with the connector having a lumen
communicating with the shaft drainage lumen, and an inflation lumen in a
side arm communicating with the inflation lumen of the shaft. The
connecter and proximal end of the shaft have complementary beveled
portions defining juncture surfaces, and the shaft has a proximal end
portion defined by the bevel which is outwardly flared in the molded
connecter. The catheter also has a sleeve of elastic material secured to
the catheter in spaced circumferential zones and defining a cavity
communicating with the inflation lumen.
A feature of the present invention is that the beveled portions at the
proximal and distal ends of the catheter shaft define an enlarged surface
area to achieve an enhanced bond between the shaft and the catheter tip
and connecter.
Another feature of the invention is that the distal end portion of the
inflation lumen is automatically formed in the tip during molding of the
tip.
A further feature of the invention is that an aperture is defined at the
distal end of the inflation lumen in the tip during molding of the tip.
Yet another feature of the invention is that the outwardly flared proximal
end portion of the catheter shaft ensures structural continuity and
integrity between the inflation lumens of the shaft and connecter.
A feature of the present invention is that the catheter shaft is insert
molded onto the tip and connecter in a simplified manner without the use
of adhesive.
A further feature of the invention is that the catheter may be made at a
reduced cost.
Another feature of the invention is the provision of methods for
constructing the catheter of the present invention.
Further features will become more fully apparent in the following
description of the embodiments of this invention and from the appended
claims.
DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a fragmentary elevational view of a catheter of the present
invention;
FIG. 2 is a fragmentary sectional view of the catheter of FIG. 1;
FIG. 3 is a fragmentary plan view of a mold for forming a tip on a distal
end of a catheter shaft;
FIG. 4 is a perspective view of a main pin for use in the mold of FIG. 3;
FIG. 5 is a fragmentary plan view of a mold for forming a connecter onto a
proximal end of a catheter shaft; and
FIG. 6 is a fragmentary schematic view of separate molds being used to
simultaneously form a tip and connecter onto a catheter shaft.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to FIGS. 1 and 2, there is shown a catheter generally
designated 10 having an elongated extruded shaft 12, a tip 14 secured to a
distal end 16 of the shaft 12, and a connecter 18 secured to a proximal
end 20 of the shaft 12. The shaft 12 has a main or drainage lumen 22
extending through the shaft, and an inflation lumen 24 extending through a
wall of the shaft.
The tip 14 has a main lumen 26 communicating with the main lumen 22 of the
shaft 12, and a pair of drainage eyes or openings 28 extending to an outer
surface 30 of the tip 14, and communicating with the main lumen 26 of the
tip. The tip has a closed distal end 32, and the tip defines a distal end
portion 34 of the inflation lumen 24 and an aperture 36 at the outer
surface 30 of the tip communicating with the lumen portion 34.
The connecter 18 has a connecting portion 38 defining a proximal end 40 of
the catheter 10 and defining a main lumen 42 of the connecter 18
communicating with the drainage lumen 22 of the shaft 12. As shown, the
proximal end of the connecter lumen 42 is enlarged to receive an adapter
of a drainage tube (not shown), and the connecter 18 has a plurality of
annular sealing rings 44 in the lumen 42 to snugly engage against the
drainage tube adapter. The connecter 18 has a side arm 46 defining an
inflation lumen 48 which communicates with the inflation lumen 24 of the
shaft 12, and a recess 50 at a proximal end 52 of the side arm 46 to
receive suitable valve means 54 for controlling passage of fluid through
the inflation lumen of the shaft and connecter. As shown, the connecter 18
has a distal annular flange 56 engaging against an outer surface 58 of the
shaft 12 and enclosing the proximal end 20 of the shaft.
The catheter also has an annular sleeve 60 of elastic material forming a
balloon adjacent a distal end of the catheter. The sleeve 60 has a pair of
opposed ends 62a and 62b which are respectively secured in circumferential
zones 64a and 64b to the outer surface 30 of the tip 14 and the outer
surface 58 of the shaft 12. In this configuration, the sleeve 60 defines a
cavity 66 underlying a central portion 68 of the sleeve 60 which
communicates with the inflation lumen through the tip aperture 36.
As shown in FIG. 2, the shaft 12 has a beveled distal end which defines a
tapered juncture surface 70 disposed at an acute angle relative to the
lower surface of the shaft as shown in the drawing. In turn, the tip 14
has a beveled proximal end 72 which defines a complementary juncture
surface 74 disposed at an obtuse angle relative to the lower surface of
the shaft as presented in the drawing, with the surfaces 70 and 74 facing
each other and being secured together to bond the tip 14 to the shaft 12.
As shown, the tip aperture 36 is located intermediate ends of the beveled
portions of the tip and shaft.
The shaft 12 also has a beveled proximal end defining a juncture surface 76
disposed at an acute angle relative to an upper surface of the shaft as
presented in the drawings, such that the proximal beveled shaft portion
defines a tapered end portion 78 containing the proximal end 80 of the
shaft inflation lumen 24, with the inflation lumen end 80 being disposed
at the apex of the acute angle. The connecter has a complementary beveled
juncture surface 82 which is disposed at an obtuse angle relative to the
upper surface of the shaft as presented in the drawing. In a preferred
form, the acute angles at both the proximal and distal ends of the shaft
may range from 30 to 45 degrees. The juncture surfaces 76 and 82 of the
shaft 12 and connecter 18 face each other and are secured together inside
the connecter 18. As shown, the shaft 12 may be longitudinally severed
along a line 84 at the proximal end 20 of the shaft 12, with the line 84
being located intermediate the inflation lumen 24 and the opposed surface
of the catheter shaft, such that the severance line 84 defines a flap 86
at the tapered end portion 78 containing the proximal end 80 of the shaft
inflation lumen 24. As shown, the flap 86 is outwardly flared in the
connecter 18, such that the flap 86 defines a curve in the proximal end 80
of the shaft drainage lumen 24, and spaces the proximal end 80 of the
inflation lumen 24 from the main lumens 22 and 42 of the shaft 12 and
connecter 18, respectively. In this manner, the outwardly flared flap 86
assures continuity and integrity between the inflation lumen 24 of the
shaft 12 and the inflation lumen 48 of the connecter 18 without leakage
into the main lumens of the catheter shaft or connecter. However, it is
noted that the tapered end portion 78 of the shaft 12 may be placed in the
outwardly flared configuration without the severance line 84 due to the
tapered configuration of the shaft proximal end 20.
As will be seen below, the tip 14 and connecter 18 are molded directly onto
the distal and proximal ends of the shaft, such that the tip and connecter
are bonded to the shaft without the use of adhesive. In a preferred form,
the shaft 12 and sleeve 60 may be extruded from a suitable elastic
material. The tip 14 and connecter 18 may then be molded onto the catheter
shaft 12, and the sleeve 60 may be bonded onto the tip and shaft after
removal of the catheter from the molds. In a preferred form, the shaft 12
and sleeve 60 may be extruded from the same material of which the tip 12
and connecter 18 are molded, and, in a suitable form, the shaft 12, tip
14, connecter 18, and sleeve 60 may be constructed from a thermoplastic
elastomer such as Kraton, a trademark of Shell Oil Company.
Referring now to FIG. 3, there is shown a mold 88 having a cavity 90 for
insert molding the distal end 16 of the catheter shaft 12 onto a tip as
will be described below. First, the distal end 16 of the catheter shaft 12
is severed at an angle to define the tapered end portion of the catheter
shaft. Next, a proximal end 92 of a main pin 94 is inserted into the
distal end of the shaft main lumen 22 in order to close the distal end of
the main lumen 22. With reference to FIGS. 3 and 4, the main pin 94 has an
elongated core 96, and a pair of opposed ears 98a and 98b extending
outwardly from the core 96 adjacent a distal end 100 of the main pin 94.
As shown in FIG. 3, a proximal end 102 of an auxiliary pin 104 is inserted
into the distal end of the shaft inflation lumen 24 in order to close the
distal end of the inflation lumen. As shown, the auxiliary pin 104 has a
central portion 105 extending distally from the shaft and aligned with the
inflation lumen 24. The pin 104 also has an outwardly turned distal end
portion 106 which is spaced from the distal end of the shaft 12, and which
is located intermediate the ends of the beveled distal shaft portion.
The distal end 16 of the catheter shaft 12 is placed in a channel 108 of
the mold 88 while the main pin 94 and auxiliary pin 104 are placed in the
mold cavity 90. In this configuration, the catheter shaft 12 closes the
proximal end of the mold cavity 90, while the end portion 106 of the
auxiliary pin 104 extends to the wall of the cavity. In addition, the ears
98a and b of the main pin 94 extend to walls of the cavity 90 and support
the core 96 and distal end 100 of the main pin 94 at a location spaced
from walls of the cavity 90. The end portion 106 of the auxiliary pin 104
and the elongated ear 98b of the main pin 94 are received in a block
positioned in recess 110.
After placement of the pins and shaft in the mold 88, a molten material,
such as a heated thermoplastic elastomer material, is injected through a
gate 112 into the mold cavity 90 to form the catheter tip. The gate 112 is
located adjacent the distal end of the shaft in order that the hottest
material contacts the shaft and obtains an excellent bond between the
shaft and tip. In addition, the gate 112 directs the material against the
core 96 in order to spread the material and maintain the desired
temperature of the material in the cavity. After the tip has sufficiently
cured, the block in recess 110 is utilized to remove the pins and tip from
the cavity 90. With reference to FIGS. 2 and 3, the core 96 of the main
pin 94 defines the lumen 26 of the tip 14, while the ears 98a and b form
the opposed drainage eyes 28 in the tip. The molded tip may be flexed
slightly in order to pass the distal end of the tip over the shorter ear
98a. Next, a source of pressurized gas may be connected to the proximal
end of the catheter main lumen in order to blow the catheter off the main
pin 94 while retained in the block. Hence, the main pin 94 passes through
one of the drainage eyes formed in the tip, and at the same time, the
auxiliary pin 104, which is also retained by the block, is removed from
the catheter through the opening 36. The central portion 105 of the
auxiliary pin 104 forms the distal end portion 34 of the inflation lumen
in the tip 14, while the distal end portion 106 of the auxiliary pin 104
forms the end of the inflation lumen and the tip aperture 36. Thus, the
catheter tip 14 is molded directly onto the distal end of the catheter
shaft 12 in a simplified manner while forming the lumen and drainage eyes
in the catheter tip. In addition, the auxiliary pin 104 conveniently forms
the distal end of the inflation lumen and automatically forms the aperture
36 communicating with the inflation lumen at the outer surface of the tip.
The tapered juncture surfaces of the catheter shaft and tip define an
enlarged surface area to enhance the bonding strength between the catheter
shaft and tip and minimize the possibility of severance during use. As
previously indicated, the catheter sleeve 60 may be bonded to the catheter
shaft and tip after formation of the tip.
With reference to FIG. 5, a mold 114 is utilized to form the catheter
connecter in a cavity 116 as described below. First, the proximal end 20
of the catheter shaft 12 is severed at an angle to form the beveled end
portion of the catheter shaft, and the shaft 12 may be also severed along
the line 84 to define the flap 86 at the proximal end of the shaft, if
desired. Next, the distal end 118 of a main pin 120 is inserted into the
proximal end of the shaft main lumen 22 in order to close the proximal end
of the shaft lumen 22. In addition, the distal end 122 of an elongated
auxiliary pin 124 is inserted into the proximal end of the shaft inflation
lumen 24 to close the proximal end of the inflation lumen 24. The proximal
end 20 of the catheter shaft 12 is placed in a channel 126 of the mold 114
in order to close the distal end of the cavity 116 while the main pin 120
and auxiliary pin 124 are positioned in the mold cavity 116. In this
configuration, a proximal end 128 of the main pin 120 closes the cavity
and supports an elongated core 130 of the main pin 120 at a position
spaced from walls of the cavity 116. As shown, the main pin core 130 has a
plurality of spaced circumferential recesses 132 for a purpose which will
be described below. A proximal end 134 of the auxiliary pin 124 closes a
proximal end of the cavity 116, and supports an elongated central
cylindrical section 136 and an enlarged proximal portion 138 at a location
spaced from the walls of the cavity 116. In this configuration, a curved
portion 140 of the auxiliary pin 124 in the flap 86 retains the flap 86 in
an outwardly flared configuration preparatory to forming the connecter.
A suitable molten material, such as a thermoplastic elastomer material, is
injected through a flared fan gate 142 into the mold cavity 116 in order
to form the connecter. The gate 142 is relatively thin in width and has a
considerable length, such that the gate 142 spreads the molten material as
it passes into the cavity 116. The gate 142 is located adjacent the
proximal end of the catheter shaft in order that the hottest material
contacts the shaft to achieve an excellent bond between the shaft and
connecter. In addition, the gate 142 directs the molten material onto the
core 130 of the main pin 120 in order to enhance spreading of the material
in the cavity and maintain temperature of the material in the mold. The
configuration of the gate 142 also minimizes the scar on the connecter
along a thin line after molding has been completed, although the gate 142
is capable of rapidly injecting a large amount of material into the
cavity.
After the connecter has sufficiently cured, the catheter and pins are
removed from the cavity. With reference to FIGS. 2 and 5, the core 130 of
the main pin 120 forms the main lumen 42 of the connecter 18 while the
recesses 132 form the connecter sealing rings 44. The main pin 120 may be
removed through an opening formed at the proximal end of the connecter 18
while the auxiliary pin 124 may also be removed by flexing the side arm 46
of the connecter 18 slightly and drawing the auxiliary pin through an
opening at the proximal end of the side arm. The central section 136 of
the auxiliary pin 124 forms the inflation lumen 48 in the connecter side
arm, while the enlarged proximal portion 138 of the auxiliary pin 124
forms the recess 50 for the valve means. As constructed, the connecter
flange 56 surrounds and encloses the proximal end 20 of the catheter shaft
12. In addition, the connecter 18 has material extending around the
proximal shaft flap 86 surrounding the proximal end of the inflation lumen
while the outwardly flared flap 86 in the connecter 18 assures continuity
and integrity between the inflation lumen 24 of the shaft 12 and the
inflation lumen 48 of the connecter side arm 46. The tapered juncture
surfaces of the shaft and connecter provide additional surface area to
enhance the bond strength between the catheter shaft 12 and connecter 18.
Thus, in this manner the catheter tip and connecter may be formed and
bonded to the catheter shaft in a molding operation which assures
simplicity in the manufacturing process of the catheter while achieving an
excellent bond between the tip and connecter and the catheter shaft. With
reference to FIG. 6, it will be seen that the proximal and distal ends 20
and 16 of the catheter shaft 12 may be inserted into the tip mold 88 and
connecter mold 114 in order to simultaneously insert mold the catheter
shaft onto the catheter tip and connecter. Of course, the cavities for the
tip and connecter may be placed in a single mold for simultaneous molding
of the tip and connecter to the catheter shaft in one mold, if desired.
The foregoing detailed description is given for clearness of understanding
only, and no unnecessary limitations should be understood therefrom, as
modifications will be obvious to those skilled in the art.
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