U.S. patent number 3,890,970 [Application Number 05/434,963] was granted by the patent office on 1975-06-24 for retention cannula or catheter and applicator.
Invention is credited to Robert L. Gullen.
United States Patent |
3,890,970 |
Gullen |
June 24, 1975 |
Retention cannula or catheter and applicator
Abstract
A self-retaining surgical cannula comprises a catheter formed as
a tube of elastic material, semirigid in character, such as
polyethylene, polyvinyl chloride or silicone rubber, etc., with a
perforate membranous front end tough, firm and sharp enough to be
inserted into body tissue without being itself cut or torn by an
internal rigid injection stylet or needle. A thin membranous
ballooning portion of the tube contracts or deflates on insertion
into the tissue and expands on application of fluid pressure within
the catheter tube to lock the cannula in place. A rigid stylet or
hollow needle, somewhat dull at its front end, is provided over
which the catheter is placed for insertion into the tissue. A limit
stop fixed on the catheter prevents over-insertion. The application
stylet, which is formed to allow fluid to flow along it into the
catheter front end, is withdrawn after the catheter tube is in
place, leaving the latter flexible enough to permit movement of the
patient and allowing needed surgical procedure while it remains in
place in the tissue.
Inventors: |
Gullen; Robert L. (Phoenix,
AZ) |
Family
ID: |
23726425 |
Appl.
No.: |
05/434,963 |
Filed: |
January 21, 1974 |
Current U.S.
Class: |
604/170.02;
604/533 |
Current CPC
Class: |
A61M
5/32 (20130101); A61M 25/04 (20130101); A61M
5/3291 (20130101) |
Current International
Class: |
A61M
25/04 (20060101); A61M 25/02 (20060101); A61M
5/32 (20060101); A61m 005/32 () |
Field of
Search: |
;128/221,215,214.4,214R,347,348,349,349B,349BV,351,344,278 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: McGowan; J. C.
Attorney, Agent or Firm: Cahill, Sutton & Thomas
Claims
What is claimed is:
1. A cannula for penetration into and retention within soft body
tissue, for injecting treating fluid into said tissue,
comprising:
a. A flexible catheter tube of resilient plastic material having
adjacent its forward end a thin membranous part expandable into a
balloon structure and having a front end closed and formed in a
point to fit over and be inserted into said tissue by a stylet,
said catheter including openings therein positioned adjacent said
closed end to permit transmission of treating fluids from said
catheter to surrounding tissue;
b. A rigid stylet slideably mounted within said catheter and having
its forward end formed into a point for supporting the pointed
closed end of said flexible catheter during insertion in said
tissue;
c. And means connected to said catheter for supplying treating
fluid therethrough to said body tissue.
2. The combination set forth in claim 1 wherein said catheter
includes a stop member formed integrally therewith and comprises an
annular ring positioned to limit the depth of penetration of said
catheter.
Description
BACKGROUND AND PRIOR ART
There is a recognized need for a flexible cannula or catheter
mechanism suitable for either intermittent or continuous injection
of fluids, such as anaesthetics, into body tissues while surgical
treatment is being given. In obstetrics practice, for example, it
is often desired to provide paracervical anaesthesia over a
prolonged period of time. It is obviously necessary that the
applicator or cannula remain in place, while not unduly restricting
movement of the patient or interfering with the necessary medical
or surgical procedures. Thus, there is need for a cannula or
catheter which can penetrate body tissue with minimal injury and
supply periodically or over a sustained time period the necessary
fluid anaesthetic, etc., while remaining securely in place and
without requiring use of complicated fastening means.
Suggestions have been made in the prior art, as in U.S. Pat. No.
3,508,545 to Reif, et al, for a flexible self-securing catheter.
The patentees have described a cannula in the form of a slender
tube of silicone rubber which has at its forward end a small
retaining barb. This device is inserted into the tissue to be
treated by means of an outer tubular needle which surrounds the
catheter and which itself is guided in an outer tube of rigid
plastic construction. After the catheter is secured in the tissue,
the inserting means are withdrawn. Thereafter, treating fluid is
injected as needed through the slender flexible tube. The barb or
retaining element in this case is necessarily soft, flexible and
quite small. It may not be retained in soft tissues as well as is
required for some cases.
Other references in the prior art have described expansible or
inflatable securing means for retaining a catheter or silimar
cannula in tissue or especially in a body cavity. Some of these are
complex mechanical devices. Thus, U.S. Pat. No. 3,692,029 described
spring-actuated mechanical wings which are pushed outwardly from
the tubular body of a trocar or injection device for retaining that
device inside of a body cavity. Other self-retaining catheters or
trocars are suggested in U.S. Pat. Nos. 1,922,084; 2,230,150;
2,320,157, and 3,438,375. See also U.S. Pat Nos. 3,544,668;
3,606,889, and 3,734,100 for other devices having relevance in some
respects to the present invention. Still other retention means are
described in U.S. Pat. Nos. 3,713,447 and 3,039,468. The latter
shows finger members or expandable membranes which, on application
of pressure or other manipulating means, serve to spread or expand
and hold the device in place against premature withdrawal or
displacement.
Most of the devices mentioned in the prior art, in the above
patents and in others, are subject to the objection that they are
rigid, either causing considerable discomfort to the patient or
requiring that the patient be restrained against movement or at
least against certain kinds of movement. In many cases, also, they
interfere with procedures or operations by the surgeon or
physician.
Other devices for special application have been specially designed
or shaped so as to be self-retaining, as in the case of an ear drum
penetrating device, described in U.S. Pat. No. 3,645,268. Such
devices are not suitable for the purposes of the present invention
which are to make use of flexible cannular means which are reliably
retained in the tissue being treated, as, for example, in the
tissues commonly requiring anaesthetic treatment in childbirth and
in analogous situations.
The use of flexible catheters or catheter tips is, of course, well
known. Some of these have been applied or inserted in tissues by
use of a more rigid guiding or inserting tool such as an interior
stylet or an external tubular guide. In some cases the guiding
means have been separate and withdrawable, as in the case of U.S.
Pat. No. 3,508,545, mentioned above. However, most of the prior art
devices do not meet the required criteria of the present invention,
that is, they lack one or more of the features of being flexible,
of being insertable into soft tissue directly, of being retained in
that tissue reliably in spite of tissue softness and/or being
designed to permit manipulation of that tissue or movements of the
patient, voluntary or involuntary, while permitting intermittent or
continuous medication, as by injection of anaesthetic fluids or the
like. A further requirement, for the present case, is that the
depth of insertion into tissue should be accurately controllable in
each case. A further and important aspect of the present invention
is the discovery that by proper design of the flexible catheter
member, although of thin elastic membranous structure, it can be
formed with a firm and sharp enough front end that it may be
inserted into the tissue to be treated. Penetration is effected
while the catheter is shrouded over a rigid stylet or hollow
needle. Moreover, this can be done without tearing or cutting the
cannula and without undue pain or injury to the patient. All rigid
elements used for application of the catheter in the present
invention, can be withdrawn and the catheter will remain securely
in place until intentionally removed.
Other objects of the invention will be further illustrated and
explained in connection with the detailed description which
follows.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 shows a plan view of the cannula, which comprises a catheter
and applicator means, with certain parts cut away or shown in
section.
FIG. 2 shows an enlarged fragmentary sectional view of the front
edge of a catheter and the inserting end of a rigid stylet, for a
typical application.
FIG. 3 shows a similar enlarged fragmentary sectional view of the
flexible catheter inserted in soft tissue and secured therein by an
enlarged balloon section, the inserting stylet having been
withdrawn.
DESCRIPTION OF PREFERRED EMBODIMENT
Referring first to FIG. 1, the flexible catheter 11 itself is shown
as being in the form of a hollow tube of firm but flexible sterile
material, such as polyethylene, vinyl chloride, silastic, or
silicone rubber. At its left or rear end this tube 11 is secured by
a flange 13 in a nipple or coupling element 14 by means of which
the catheter may be attached to the outlet 15 of a syringe 20.
Towards its forward or left end, the catheter is provided with a
fixed or integral stop member or limit device in the form of a ring
16. In front of the stop member 16, the tube body is reduced in
thickness at 17 to form a normally expanded or expandable "balloon"
member when the catheter is in place in tissue 40, FIG. 2. Stop
member 16, of course, serves to limit the depth of penetration to
which tube 11 can be inserted into tissue 40.
In its front end portion, the tube 11 is formed as a thin membrane
at 21 with a sharp cutting edge 22; being made of very tough and
strong film material, its body can be stretched over the dull point
of a stylet or needle 25 without being cut or torn by the needle.
The stylet 25 is blunt at its front end 29 but the tube 11 at its
front end 21 is firm and sharp enough that the assembly can be
inserted in tissue such as that involved in obstetrics without
cutting or tearing the film. The front end part 21 is provided with
perforations 23. Needle 25 may be hollow, if desired, in which case
similar perforations 27 in its forward end allow injection of fluid
through the front of the catheter from the syringe 20 or from any
other soruce. If stylet 25 is not hollow, it is shaped or sized so
that fluid from source 20 may flow along it into the front end of
the catheter 11.
The stylet 25 is flanged at 28, at its rear or right end, FIG. 1;
this flange fits within the coupling connection 14 to syringe 20;
the syringe or fluid supply source may be of any suitable type, as
will be obvious. When the catheter 11 is attached to the syringe 20
through outlet coupling 14, and the rigid stylet 25 is in place
within the catheter as in FIG. 1, the thin but penetrating membrane
part 21 being stretched over the end of the needle, the balloon
part 17 may be normally expanded somewhat as shown in dotted lines
in FIG. 1. However, this balloon part 17 smooths out as the needle
or stylet carrying the outer membrane cover is forced into the
tissue 40, as seen in FIG. 2. Outlets 23 in the membrane, and
openings 27 in the stylet or needle, if the latter is hollow,
permit the injection of anaesthetic fluid or other medication into
the tissue from the syringe 20. This action of injecting fluid
moreover, assists in expanding and holding the balloon section 17
in expanded tissue-locking position, as shown in FIG. 3. The
membrane at 17 may expand somewhat, even without this internal
pressure, as the stylet is withdrawn from the tube 11, tending also
to lock the latter in place within the tissue 40.
An important aspect of the present invention is the discovery,
mentioned above, that the thin membrane end of the catheter can be
drawn over the stylet and retain sufficient sharpness to penetrate
the tissue without undue difficulty and without tearing or cutting
the thin membrane part 21, so that the catheter front end is neatly
inserted into the tissue and locked there with minimum damage to
the tissue. Experience has shown that the flexible catheter
element, in the cannula, when made of a high grade, relatively firm
synthetic rubber or stretchable plastic of sterile and sanitary
type, can be inserted smoothly with the needle and is readily
stripped off to remain securely in place when needle 25 is
withdrawn. However, by applying some fluid pressure from the
syringe as the needle or stylet is withdrawn from the tube 11, FIG.
3, the stripping of the tube 11 off the needle is further
facilitated and the balloon part 17 is kept fully expanded. Thus,
the device is locked firmly and reliably in place. To withdraw tube
11 from the tissue, stylet 25 is reinserted to deflate the balloon
part; the dull point on the stylus prevents cutting the catheter.
This permits the balloon 17 to collapse. Then, the whole device can
be withdrawn from the tissue without injury to the latter.
The original syringe 20 is employed while continuing to supply
treating fluid, or the tube 11 may be attached to another fluid
source after the stylet has been withdrawn from the catheter, as in
FIG. 3. If desired, the stylet may be made retractable without
requiring that it be completely removed from tube 11, but wherever
a stiff needle or stylet would cause discomfort to the patient or
would restrict the patient's movements undesirably, or would
interfere with proper medical or surgical procedures, it should be
removed. This may be done by disconnecting the connection or
coupling 14, removing the stylet from the catheter 11, and
reconnecting the latter to the syringe or to some other source of
treating fluid, thus repressuring the balloon part 17 to hold the
catheter in place.
While reference has been made to treatment of cervical tissue or
related tissue with anaesthetic fluids, it will be understood that
the invention is suitable for treatment of other soft tissue with
anaesthetics or with other treating agents, according to good
medical practice and with appropriate skill. It will be obvious
that various modifications can be made in the apparatus and in its
application, without departing from the spirit and purpose of the
invention. The particular materials employed for the various parts
may be varied, in accordance with good practice in the medical
instrument field. Thus, the tubes 11 will ordinarily be expendable,
used only once, while the applicator means 25 and other mechanical
parts may be of stainless steel or the like and sterilized and
reused as often as needed. Obviously, any of the parts may be
expendable or they may be made of materials suitable for
sterilization and reuse.
It is intended by the claims which follow to cover the invention
and its obvious variations and modifications as broadly as the
state of the prior art properly permits.
* * * * *