U.S. patent number RE31,855 [Application Number 06/443,321] was granted by the patent office on 1985-03-26 for tear apart cannula.
This patent grant is currently assigned to Cook, Inc.. Invention is credited to Thomas A. Osborne.
United States Patent |
RE31,855 |
Osborne |
March 26, 1985 |
**Please see images for:
( Certificate of Correction ) ( Reexamination Certificate
) ** |
Tear apart cannula
Abstract
This invention relates to a flexible cannula comprising material
which tears readily in a longitudinal direction and can thus be
easily removed by pulling tabs on opposite sides of the cannula
apart after the catheter or other device has been inserted into the
body.
Inventors: |
Osborne; Thomas A.
(Bloomington, IN) |
Assignee: |
Cook, Inc. (Bloomington,
IN)
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Family
ID: |
27033496 |
Appl.
No.: |
06/443,321 |
Filed: |
November 22, 1982 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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965703 |
Dec 1, 1978 |
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Reissue of: |
173960 |
Jul 31, 1980 |
04306562 |
Dec 22, 1981 |
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Current U.S.
Class: |
604/161; D24/112;
604/164.05 |
Current CPC
Class: |
A61M
25/0668 (20130101) |
Current International
Class: |
A61M
25/06 (20060101); A61M 25/06 (20060101); A61M
025/00 () |
Field of
Search: |
;604/158-172
;128/784 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
"High Quality Hose Constructions From Teflon TFE Fluorocarbon
Resins", DuPont Tech. Services Laboratory, Ribbans, TR#138. .
"Percutaneus Insertion of a Permanent Transvenous Pacemaker
Electrode Through the Subclavian Vein" Can. J. Surgery, Friesen et
al., 3-77, pp. 131-135. .
Article-"Eine Neue Methode zur Perkutanen Implantation permaneter
Herz Schritt Macher", (A New Method for the Percutaneous
Implantation of Permanent Pacemakers) by H. Sterz et al. (with
translation)..
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Primary Examiner: Padgett; Benjamin R.
Assistant Examiner: Wallen; T. J.
Attorney, Agent or Firm: Woodard, Weikart, Emhardt &
Naughton
Parent Case Text
This is a continuation, of application Ser. No. 965,703 filed Dec.
1, 1978, now abandoned.
Claims
The invention claimed is:
1. A cannula comprising
a tubular structure having one end which has a pair of open ended
slits, said tubular structure being compatible for insertion within
the body and having an opposite end adapted to be inserted in the
body with said one end extending out of the body, said tubular
structure being formed of flexible material having the physical
property of molecular orientation whereby a tear in said material
runs readily only in a longitudinal direction along the length of
said tubular structure, said tubular structure being flexible from
its inner diameter to its outer diameter and continuously smooth on
its inner surface and outer surface, said slits each having a
closed end located between said one end and said opposite end;
a first tab defined by said slits on one side of one end of said
tubular structure; and
a second tab defined by said slits on the other side of said one
end of said tubular structure whereby when said tabs are pulled
apart, said structure tears longitudinally along its length
beginning at said closed ends and extending to the opposite end of
said tubular structure.
2. The cannula of claim 1 in which the flexible material is a
plastic.
3. The cannula of claim 1 in which the flexible material is
polytetrafluoroethylene.
4. The cannula of claim 1 in which said opposite end is tapered so
as to define a tapered end portion, said tubular structure having
an inner surface and an outer surface and having a substantially
uniform thickness from the inner surface to the outer surface
except at the tapered portion.
5. The cannula of claim 1 in which said tabs are integral with said
tubular structure and are separated by said open ended slits.
6. A cannula kit comprising:
a cannula including a tube of flexible material having the physical
property of molecular orientation whereby a tear in said material
runs readily only in a longitudinal direction along the length of
the tube, said tube being soft and flexible from its inner diameter
to its outer diameter; a first tab on one side of one end of said
tube, a second tab on the other side of said one end of said tube
whereby, when said tabs are pulled apart, said tube tears
longitudinally separating said tube from any object within said
tube;
a percutaneous needle;
a wire guide;
a dilator;
and a bag containing said cannula, guide and dilator.
7. The cannula kit of claim 6 where said bag is hermetically sealed
and made of plastic.
8. A cannula comprising:
a tubular structure having one end which has a pair of open ended
slits, said tubular structure being compatible for insertion within
the body and having an opposite end adapted to be inserted in the
body with said one end extending out of the body, said tubular
structure being continuously smooth on its inner surface and outer
surface,
means for allowing the opposite end to remain continuously smooth
on its inner surface and outer surface while the opposite end is
within the body, said means for allowing including said tubular
structure being formed of flexible material having the physical
property of molecular orientation whereby a tear in said material
runs readily only in a longitudinal direction along the length of
said tubular structure,
a first tab defined by said slits on one side of said one end of
said tubular structure; and
a second tab defined by said slits on the other side of said one
end of said tubular structure whereby, when said tabs are pulled
apart, said structure tears longitudinally along its length
beginning at said slit closed ends and extending to the opposite
end of said tubular structure.
9. A removable cannula for introducing a member into an internal
organ of the body, said cannula comprising:
(a) a tubular structure compatible for insertion within the body,
said tubular structure having one end and having an opposite end
adopted to be inserted into the body with said one end extending
out of the body, said tubular structure being flexible from its
inner diameter to its outer diameter, said tubular structure having
an internal passageway for passage of a member into an internal
organ of the body; and
(b) removal means for removing said cannula from about the member
after the introduction of the member into the body through the
internal passageway of said tubular system, said removal means
including means for providing for the inserted portion of said
tubular structure to remain continuously smooth on its inner
surface and its outer surface during insertion, said removal means
including:
(i) said flexible material having the physical property of
molecular orientation whereby a tear in said material runs readily
only in a longitudinal direction along the length of said tubular
structure,
(ii) said one end of said tubular structure having a pair of open
ended slits, said slits having closed ends located between said one
end and said opposite end,
(iii) a first tab defined by said slits on one side of said one end
of said tubular structure and
(iv) a second tab defined by said slits on the other side of said
one end of said tubular structure whereby, when said tabs are
pulled apart, said structure tears longitudinally along its length
beginning at said closed ends of said slits and extending to the
opposite end of said tubular structure. .Iadd.
10. A cannula kit comprising:
a tube of flexible plastic material compatible for insertion within
the body and having the physical property of molecular orientation
whereby a tear in said material runs readily only in a longitudinal
direction along the length of the tube, said tube being soft and
flexible from its inner diameter to its outer diameter; a first tab
on one side of one end of said tube, and a second tab on the other
side of said one end of said tube whereby, when said tabs are
pulled apart, said tube tears longitudinally separating said tube
from any object within said tube; and a dilator. .Iaddend.
.Iadd.11. A cannula comprising:
a tube of flexible material compatible for insertion within the
body and having the physical property of molecular orientation
allowing a tear in said material to run readily only in a
longitudinal direction along the length of the tube, said tube
being soft and flexible from its inner diameter to its outer
diameter and tapered at one end adapted for insertion within the
body; a first tab on one side of the end of said tube opposite said
one end and a second tab on the other side of said opposite end of
said tube whereby, when said tabs are pulled apart said tube tears
longitudinally separating said tube from any object within said
tube. .Iaddend. .Iadd.12. The cannula of claim 11 wherein said tube
is continuously smooth on its outer surface. .Iaddend. .Iadd.13.
The cannula of claim 12 wherein said tube is continuously smooth on
its inner surface. .Iaddend. .Iadd.14. A cannula comprising:
a tubular structure having one end which has a pair of open ended
slits, said tubular structure being compatible for insertion within
the body and having an opposite end adapted to be inserted in the
body with said one end extending out of the body, said tubular
structure being formed of flexible material having the physical
property of molecular orientation allowing a tear in said material
to run readily only in a longitudinal direction along the length of
said tubular structure, said tubular structure being flexible from
its inner diameter to its outer diameter, said slits each having a
closed end located between said one end and said opposite end;
a first tab defined by said slits on one side of one end of said
tubular structure; and
a second tab defined by said slits on the other side of said one
end of said tubular structure whereby when said tabs are pulled
apart, said structure tears longitudinally along its length
beginning at said closed ends and extending to the opposite end of
said tubular structure without the need for any mechanical means
for facilitating longitudinal separation of said tube. .Iaddend.
.Iadd.15. The cannula of claim 14 in which said tubular structure
is continuously smooth on its outer surface. .Iaddend. .Iadd.16. A
cannula comprising: a tube of flexible plastic material compatible
for insertion within the body and having the physical property of
molecular orientation whereby a tear in said material runs readily
only in a longitudinal direction along the length of the tube, said
tube including a non-mechanical means for longitudinally tearing
apart said tube, said tube being soft and flexible from its inner
diameter to its outer diameter; a first tab on one side of one end
of said tube, and a second tab on the other side of said one end of
said tube whereby, when said tabs are pulled apart, said tube tears
longitudinally solely due to said non-mechanical means, separating
said tube from any object within said tube. .Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a cannula used as an aid for
insertion of catheters and other instruments into the body and more
particularly to a cannula that is easily removed after the
insertion is completed.
2. Brief Description of the Prior Art
It is desirable that after a catheter or other body probe device
has been inserted into place within a blood vessel that the
apparatus used to aid the insertion is easily removable. When sharp
devices such as hollow needles are left in place while the catheter
or other device is being utilized, there is a danger that the
needle may pierce through the vessel, causing tissue damage and
rendering the catheter useless. In assemblies where the needle is
removable, this problem is alleviated; however, in these cases, the
cannula which is used as a passageway into the blood vessel, often
cannot itself be easily removed when the probe or catheter that has
been inserted has an enlarged proximal end. The inability to easily
remove the cannula is a disadvantage in circumstances when the
inserted probe or catheter must remain in the body for an extended
period of time to be permanently implanted.
Various removable devices have been developed using frangible,
hollow needles (see Rubin, U.S. Pat. No. 3,382,872; MacGregor, U.S.
Pat. No. 3,550,591; Warren, U.S. Pat. No. 3,598,118 and Nerz, U.S.
Pat. No. 3,677,243). In these devices the hollow needle must have a
larger diameter to accommodate the catheter within the device. The
larger size of the hollow needles can be a cause of additional
tissue damage. Because of their rigidity and sharpness, these
needles act as poor cannuli in situations where probes must be
inserted and removed repeatedly, and they cannot be used at all
when the cannula must be used as an aid in advancing the probe
along the interior of the blood vessel.
Ansari, U.S. Pat. No. 3,545,443, utilizes dual hollow concentric
needles, each having a longitudinal slot. After insertion, the
needle assembly is removed and twisted in such a manner that the
slots are aligned. The catheter then can pass through the slots
thus removing the needle. This non-frangible assembly possesses
many of the same disadvantages that the other hollow needle devices
have. In addition, because there are two hollow needles, an even
larger needle diameter is necessary to accomodate the same size
catheter. The slots in the needles may also cause additional tissue
damage and potentially may not be able to effectively prevent blood
loss and air emboli.
Gauthier, U.S. Pat. No. 3,094,122, uses a percutaneous needle that
is inside the catheter. After insertion, the needle is removed
lengthwise from the catheter. There are several restrictions upon
this method. The needle must be longer than the catheter and the
method is only adaptable for insertion of hollow devices or
catheters and cannot be used where various probes and leads are to
be inserted. Guttman, U.S. Pat. No. 3,225,762, is similar to the
Gauthier device except that the catheter has a slot for removal of
the needle after insertion. This eliminates the need to have a
needle that is longer than the catheter, however, there may be
undesirable leakage through the slit, particularly when the
catheter is bent at or near the slit. This invention also cannot be
used where the probe to be inserted within the vessel is not
hollow.
Reilly, U.S. Pat. No. 3,570,485, provides a flexible cannula,
placed over the percutaneous needle, that is slotted along its
length. After insertion, the needle is removed and the cannula can
then act as a sheath for insertion of the catheter or other device.
After insertion of the probe, the cannula can be removed by sliding
the catheter or other device through the slit in the cannula.
Although this invention is flexible and can be adopted for
insertion of both catheters and non-hollow probes, the longitudinal
slot may not provide a blood or airtight seal. This problem may be
reduced by increasing the thickness of the cannula, however this
would necessitate either the use of a larger puncture diameter or a
smaller probe. Further, removal of the cannula requires gripping
both the cannula and the inserted catheter and physically pulling
them apart. Applying such a force upon an object that is partially
inserted into the body may cause tissue damage. There is also the
potential of accidentally pulling the catheter out from its
inserted position.
The Reilly patent has a further limitation in its collapsibility.
When the Reilly cannula is empty prior to insertion of the catheter
or probe, it collapses upon itself at the puncture site with the
purpose of preventing blood loss. However, this attribute creates a
disadvantage in that a stiff catheter with a stiff tapered distal
end is required in order to reopen the cannula for reinsertion;
therefore, flimsy and flexible leads, such as pacemaker leads and
blunted tipped catheters, such as balloon tipped catheters, are
unadoptable for use with this device.
BRIEF DESCRIPTION OF THE PRESENT INVENTION
The present invention is a flexible cannula that readily tears in a
longitudinal direction along the length of the structure because it
comprises material that has a longitudinal orientation. Because it
is flexible and hollow, it acts as a good cannula where devices
must be repeatedly inserted, left within the body for a period of
time, or advanced along the interior of the vessel.
Because of its longitudinal orientation, the present invention can
readily be removed by tearing the structure along its length along
two longitudinal lines thereby splitting it into two halves. This
is a particular advantage where the lead or probe is to be
permanently inserted and has large fittings or connectors on its
proximal end such that the cannula cannot merely be slipped off the
end of the probe.
Because no force needs to be applied to the partially inserted
probe when the cannula is split apart, the potential of
accidentally pulling the probe out from its desired position is
diminished.
There are numerous specific applications in which the present
invention can be utilized. One such application is for suprapubic
insertion into the bladder. Catheters used in this type of
application normally have enlarged proximal ends and remain in the
body for prolonged periods of time.
Another application is transvenous insertion of permanent pacemaker
leads. Such leads separate into various electrodes at the proximal
end, each electrode being significantly larger than the general
diameter of the lead. After insertion of the distal end into the
desired position within the heart. These leads must themselves be
implanted beneath the skin and connected to a power source. In the
past, it has been the practice to remove the sheath by slitting it
with a scapel, in order to enable the implantation of the
electrodes. Reference is made to "Percutaneous Insertion of a
Permanent Transvenous Pacemaker Electrode through the Subclavion
Vein" in the Canadian Journal of Surgery, vol. 20, pg. 131 which is
descriptive of this technique.
There are several existing techniques which can take advantage of
the benefits of the present invention. In one method the cannula is
inserted into a blood vessel about percutaneous needle. The needle
is then removed, and a catheter or other probe device is inserted
through the sheath and the combination is advanced into position.
The cannula can then be slipped out of the body and split by
pulling a pair of tabs on the end thereof thus being removed from
the probe.
In another method, a hollow needle is inserted into a vessel. A
wire guide is then passed through the needle into the interior
portion of the vessel. The needle can then be withdrawn and the
cannula with a dilator inserted into the vessel over the wire
guide. The assembly is advanced into position and the dilator and
wire guide are removed. A catheter or probe can next be passed into
the vessel through the cannula. The cannula is withdrawn from the
body and split apart thus being removed from about the probe.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of the splitable cannula in combination with
a dilator and wire guide.
FIG. 1A is an enlarged view similar to FIG. 1 of the structure of
FIG. 1 with portions broken away to show internal structure.
FIG. 1B is an enlarged fragmentary view of a portion of the
structure of FIG. 1.
FIG. 2 is a side view of a hollow percutaneous needle.
FIG. 3 through FIG. 11 are sections through a blood vessel showing
a procedure.
FIG. 3 illustrates the needle inserted within the blood vessel.
FIG. 4 shows a wire guide inserted into the vessel through the
incision needle.
FIG. 5 shows the incision withdrawn from the puncture site.
FIG. 6 shows the wire guide percutaneously positioned within the
blood vessel.
FIG. 7 illustrates the splitable sheath and dilator combination
inserted into the vessel over the wire guide.
FIG. 8 illustrates the guide dilator and splitable cannula assembly
advanced into the desired position within the vessel.
FIG. 9 shows the splitable cannula in position after the wire guide
and dilator have been removed.
FIG. 10 illustrates a probe inserted within the splitable
cannula.
FIG. 11 shows the cannula after being split into two parts.
FIG. 12 through FIG. 16 are sections through a blood vessel showing
a further procedure.
FIG. 12 illustrates a splitable cannula disposed about the incision
needle and inserted in this manner into the blood vessel.
FIG. 13 shows the splitable cannula inserted within the vessel
after the incision needle has been removed.
FIG. 14 illustrates the probe inserted within the cannula.
FIG. 15 shows the probe and splitable cannula combination advanced
into the desired position within the vessel.
FIG. 16 illustrates the cannula split into two parts.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A preferred embodiment of the present invention is shown in
combination with a dilator and a wire guide in FIG. 1. The
splitable cannula 10 is disposed about the dilator 11 which, in
turn, is disposed about the wire guide 12. The distal end 13 of the
dilator is tapered for enlarging the puncture site to accommodate
the splittable cannula. Where the diameter of the splittable
cannula is of a sufficiently large size, the dilator that is used
has a second tapered portion 14. The tubular portion 15 of the
splittable cannula has approximately uniform thickness and diameter
except at its distal end 16 where there is a slight taper to create
an appropriately snug fit with the dilator and also to facilitate
the enlarging of the puncture site to accommodate the cannula. The
proximal end 20 of the cannula is slit longitudinally producing two
open ended slits at opposite sides of the tubular structure 21 and
22, thus creating two tabs 23 and 24 which are attached to knobs 25
and 26 by being inserted between the screw 30 and 31 and socket 32
and 33 portions of the knobs. At the proximal end of the dilator 11
is a knob-like clamp 34 which maintains the two telescoping layers
of the dilator 11 in position.
FIG. 1B is a cross-sectional view showing a representative one of
the tabs 23 attached to one of the knobs 25 which comprises a screw
30 and socket 32 combination. The screw 30 is screwed into the
socket 32 with the end 23 in the socket. The force between the
screw 30 and socket 32 maintains the end of the tab in position.
The knobs 25 and 26 are used to aid in gripping the device when it
is split apart.
FIGS. 3 through FIG. 11 shows a procedure whereby a probe having
relatively large fittings on its proximal end is placed in
position. The probe might be, for example, a catheter used to
measure the flow of saline solution through the blood vessel. Such
catheters have a balloon at the distal end which operates to close
off the flow through the blood vessel. This balloon is inflated by
placing air into a fitting such as the fitting 61. Another fitting
such as fitting 62 might receive the saline solution. Still another
fitting such as the fitting 63 functions to provide a coupling to a
thermistor which measures the temperature of the saline solution
blood mixture as it moves by the thermistor at still another point
along the catheter.
FIG. 3 shows the percutaneous needle 40 inserted through the skin
and body tissue 50 and into a blood vessel 51. FIG. 4 shows the
subsequent step of inserting the wire guide 12 into the blood
vessel 51 through the needle 40. In FIG. 5 the needle 40 has been
removed from the puncture site leaving the wire guide as in FIG. 6.
In FIG. 7 the splitable cannula 10 and dilator 11 combination is in
the process of being inserted into the blood vessel 51 about the
wire guide 12. The cannula, dilator and wire guide combination have
been advanced into the desired position in FIG. 8. In FIG. 9 the
wire guide and dilator have been removed leaving the splittable
cannula 10 in its desired position. FIG. 10 shows a probe 60 being
inserted into the blood vessel through the splitable cannula 10.
The probe elements 61, 62 and 63 are fittings which are permanently
mounted on the proximal end of the probe 60. In FIG. 11 the
splittable cannula has been removed from the puncture site and
split apart into two portions 70 and 71 and in this manner has been
separated from the inserted probe.
In an alternative technique, the splittable cannula 10 may be
inserted within the blood vessel 50 directly about the needle 40.
FIG. 12 shows this combination inserted within the blood vessel.
FIG. 13 illustrates the splitable cannula 10 inserted within the
blood vessel after the incision needle 40 has been removed from the
puncture site. FIG. 14 illustrates the probe 60 introduced into the
blood vessel 51 through the splittable cannula 10. In FIG. 15 the
probe 60 and cannula 10 combination have been advanced into
position. FIG. 16 shows the cannula 10 withdrawn and split off
leaving the probe in position.
Teflon (Teflon is the Dupont trademark for polytetrafluoroethylene)
used in the preferred embodiment is virgin material i.e., has not
previously been used, or reground. It is free of foreign matter and
dye marks. These characteristics are required to ensure
compatibility for insertion into the body. Teflon is the preferred
material because it can be longitudinally oriented through
extrusion, although other plastics may be useable. It is known, for
example, that polyethylene obtains the required longitudinal
orientation characteristics if it is stretched after extrusion.
However, polyethylene is not used in the preferred embodiment
because it is understood that the orientation process for
polyethylene is more difficult to perform properly.
A standard extrusion process orientates the Teflon and forms it
into the tubular shape of the cannula. The Teflon is blended with
an extrusion aid or lubricant, preferably naphtha, and a thermally
stable pigment. The pigment used may be any stable pigment that is
acceptable for insertion within the body. The naphtha normally
comprises between 17 and 20% by weight and the concentration of
pigment should be less than 2%. Then, at temperatures above
75.degree. F., the compound mixture is preformed. The object of
preforming is to compact the powder into a cylinder which is about
one-third of the original volume. The preforming pressure is
between 100 and 300 lbs/sq. in. The preform is then extruded
through an extrusion die at pressures of approximately 20,000 psi.
After extrusion the Teflon tubing is passed through a drying oven
at a graduated temperature increasing from 300.degree. F. to
575.degree. F. The heat from this oven vaporizes the lubricant. The
Teflon tubing is next led through a sintering oven, at temperatures
of at least 621.degree. F., allowed to cool, and rolled onto
spools.
In the manufacturing of the cannula, the Teflon tubing is cut off
radially to define one end of the cannula and slit at that one end
with a cutting instrument at opposite ends of the same end to form
the two opposed slits 20 and 21. This slitting operation creates
the tabs 23 and 24 which are used to pull apart the cannula and the
slits define the location of the beginning of the tears when the
tabs are pulled. A screw and socket combination 25 and 26 is
attached to each tab, as illustrated in FIG. 1B, to facilitate the
gripping and pulling of the tabs.
An appropriate length is then measured and a heat gun applied to
the tubing. Upon application of this heat, the tubing is stretched,
yielding a tapered end. The tip is then cut at a point where the
inside diameter of the cannula approximates the outside diameter of
the dilator which will be used with the particular cannula. This
tapering method serves two purposes. First, the outside diameter is
tapered to facilitate insertion of the cannula into the body.
Second, a tight fit with the probe at this end minimizes blood
loss.
In one preferred embodiment of the present invention, the thickness
of the structure from the inner surface to the outer surface is
0.010 inch with a tolerance of plus or minus 0.002 inch. The
required diameter of the cannula will vary with the diameter of
various dilators which are used in combination with the sheath. It
is estimated that useful sizes will range from an inner diameter of
0.05 inch to an inner diameter of 0.2 inches; however, there may be
applications requiring larger or smaller dimensions. The inner
diameter tolerance is plus 0.002 inch and minus 0.000 inch.
In the preferred embodiment, the cannula is sterilized using
ethylene oxide and packaged with a sterilized percutaneous needle,
a wire guide, and a dilator in a hermetically sealed plastic
bag.
While the invention has been illustrated and described in detail in
the drawings and foregoing description, the same is to be
considered as illustrative and not restrictive in character, it
being understood that only a preferred embodiment has been shown
and described and that all changes and modifications that come
within the spirit of the invention are desired to be protected.
* * * * *