U.S. patent number 3,885,561 [Application Number 05/496,690] was granted by the patent office on 1975-05-27 for catheter.
Invention is credited to Charles N. Mazal Cami.
United States Patent |
3,885,561 |
Cami |
May 27, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
Catheter
Abstract
A catheter for epidural anesthesia comprising a plastic tube
which has its near end open permitting adaptation to the tip of
syringe or the like, and the opposite or distal end rounded and
carrying embedded in the interior of same a metallic piece opaque
to X-rays; having in the distal end, which is closed, from two to
six longitudinal slits, each of which is both longitudinally and
circumferentially offset from the nearest adjacent slit so that the
diametral planes in which said slits are placed form a dihedral
angle of at least 45.degree., and furthermore by the fact that none
of the diametral planes in which each slit is located has more than
one slit, thus affording the catheter practically the same rigidity
as that of a catheter having no slit whatever.
Inventors: |
Cami; Charles N. Mazal (Mexico
6, D.F., MX) |
Family
ID: |
26640935 |
Appl.
No.: |
05/496,690 |
Filed: |
August 12, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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312236 |
Dec 4, 1972 |
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Current U.S.
Class: |
604/247; 137/493;
137/848; 604/523 |
Current CPC
Class: |
A61M
25/0108 (20130101); A61M 25/007 (20130101); A61M
2025/0007 (20130101); Y10T 137/7771 (20150401); Y10T
137/7884 (20150401) |
Current International
Class: |
A61M
25/00 (20060101); A61M 25/01 (20060101); A61m
005/00 (); A61b 025/00 (); A61b 027/00 () |
Field of
Search: |
;128/214,2R,2B,130,224,348,349R,349B,349BV,35R,35V |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Medbery; Aldrich F.
Attorney, Agent or Firm: Ladas, Parry, Von Gehr, Goldsmith
& Deschamps
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in part of my co-pending
application Ser. No. 312,236, filed Dec. 4, 1972, and now
abandoned, for "Catheter."
Claims
I claim:
1. A catheter for epidural anesthesia composed of a plastic
material having its near end open and adapted for connection to a
syringe and having its distal end closed and rounded and having
embedded in its internal portion a metallic piece which is opaque
to X-rays, said catheter having near its distal end a plurality of
longitudinal slits for delivering anesthetic, each of said slits
being both longitudinally and circunferentially offset from the
nearest slit so that each slit be placed in a different diametral
plane, and being so spaced from the adjacent slit that the
diametral planes on which they are located form an angle of at
least 45.degree., thus giving the catheter substantially equal
rigidity to that of a catheter having no slit whatever.
2. The catheter for epidural anesthesia as described in claim 1,
wherein the slits for delivering anestesic consist of from two to
six slits longitudinally spaced from each other.
3. The catheter for epidural anesthesia as described in claim 1,
wherein the metallic portion for detection by X-rays embedded
within the distal end of the catheter is a piece of cylindrical
wire which is inert to biological tissues and does not engage in
ion exchange with the biological liquids and tissues.
Description
BACKGROUND OF THE INVENTION
In recent years the technique of administering anesthetics in
liquid form directly into the spinal column, specifically into the
peridural space, has been improved, achieving benefits in
comparison to general anesthesia of the patient, and particularly
to that accomplished be means of anesthetic gases, in cases of
surgery particularly of the lower abdomen and the legs, because the
sensibility of the patient is successfully isolated in these areas
without loss of consciousness, and without saturating the blood
stream with anesthetic solutions.
Epidural anesthesia has also proved advantageous in childbirth,
whether or not controlled by the introduction of ocitosics.
To administer this anesthesia it was at first necessary to insert a
special needle into the resistant external tissues, between the
vertebrae and through the softer and extremely delicate internal
tissues before achieving penetration into the epidural space.
At first the anesthetic was administered directly through the
needle, with the corresponding danger which a sharp pointed
instrument of this character represents in such a critical
spot.
Later on it became preferable to effect the operation by means of
introducing a flexible tube of thermoplastic material of a diameter
which could be passed through the inside of the needle which had
been inserted into the body by direct puncture or by incision,
permitting thereafter the extraction of the needle sliding over the
tube when the latter had been placed in the desired location; this
is tested by extracting through the tube a biological liquid
sample. The tube of the first catheter had both ends cut square,
and on one end it included a small adapter so that once the needle
was withdrawn, a syringe with anesthetic could be attached.
Notwithstanding the advantages of the flexible catheter with square
cut ends, over the administration of anesthetics by a simple
needle, the edges of the square cut of the tube produce trauma in
the delicate tissues through which the catheter passes and cause
postoperatory pain to the patient; in addition, since the said
catheter has no penetration markings, it is difficult to know to
what depth the tube had been inserted.
Furthermore, with this tube the exact location of same in the
epidural space is unknown, since the thermoplastic material of
which it is made cannot be detected with X-rays.
Another problem caused by this catheter with square cut ends is
that the orifice in the end of the tube frequently becomes blocked,
since it is precisely the end, thereof that is used to achieve
penetration, and hence in the opening of the tube tiny clots,
fibers and particles of the tissue itself are deposited,
obstructing the passage of the anesthetic liquid.
Subsequently, in order to avoid the foregoing problems, a catheter
was developed which had the penetration tip at its distal end
rounded to a bullet shape to reduce the trauma of adjacent tissues
and to facilitate penetration through them.
The orifices for supplying the anesthetic in said catheter
consisted of two practically circular lateral apertures near the
distal end, diametrically opposite each other, and slightly
separated from each other in respect to the lengthwise axis of the
catheter.
Furthermore, in this catheter or probe indelible markings were
provided separated by a certain interval, with the object of
determining the penetration of the catheter.
Notwithstanding the progress achieved with this catheter, the shape
and location of the lateral orifices seriously affected the
strength of the tube, and weakened it, since the catheter in its
penetration travel generally bends principally at the said
orifices, causing serious complications such as the obstruction of
the flow of the anesthetic liquid, difficulty in the withdrawal of
the catheter when the bend is very pronounced, and occasionally the
tip of the catheter comes off; obviously it is more difficult to
accomplish penetration of the catheter under such conditions.
In addition to the problems mentioned with each of the catheters
individually cited, they all uniformly have the drawback that,
since within the epidural space there is a higher pressure than
atmospheric pressure, the cephalorachidian liquid tends to escape
through the catheter in cases where accidentally or intentionally
the syringe is disconnected from the adapter or the latter from the
catheter, thus producing a loss of the cited liquid with
corresponding serious results.
In some catheters, in order to determine their position within the
human body, heavy metals have been mixed with the plastic material;
while this does produce a certain opacity which can be detected by
X-rays, it is not very precise, since the epidural space into which
the catheter is to penetrate is surrounded by bone tissue.
The above references are the best known in the field of catheters
for epidural anesthesia; however, outside of this field, and for
the sole purpose of differentiating them from the present
invention, drain tubes or shunts operating on differential pressure
may be mentioned; they are placed in the body permanently or for
prolonged periods; some of them are for draining cerebro-spinal
fluid to either the atrium or the peritoneum. Since the pressure in
the atrium is greater than the pressure in the cerebroventricular
space, the drain tube has been provided with valving cuts at one of
its ends, so as to prevent the back-flow of blood toward the
ventricle; at its other end the drain tube has circular
perforations; some of these tubes have as a backing member an inner
concentric cylindrical body near the cuts to prevent the latter
from becoming blocked; the arrangement of the cuts has not been
made in these shunts specifically to give the tube strength, and
furthermore, one of their ends generally carries circular
perforations. Obviously, both the structural elements of these
pressure shunts and their application are outside of the field of
catheters for supplying epidural anesthesia of the present
invention.
SUMMARY OF THE INVENTION
In view of the foregoing it is one object of the present invention
to provide a catheter for epidural anesthesia which has its distal
end rounded to prevent damage to the adjacent tissues during its
penetration, thereof, and which has embedded in the material of
this distal end a piece of wire which is inert to biological
tissue, which does not effect an ion interchange with biological
fluids or tissue, and which may be stainless steel, with a low
content of carbon, gold, platinum, alloys of cobalt, chrome and
molybdenum, etc., and which is clearly detectable by X-rays even
when the catheter is surrounded by bone tissue; and having
penetration interval markings which will allow the user to
determine the exact location of its application.
Another object of this invention is to provide a catheter having
near its distal end a plurality of longitudinal radial slits to
dispense the anesthetic which open only when a syringe or the like
attached to the near end of the catheter develops a greater
positive pressure than that prevailing in the cavity in which the
anesthetic is to be delivered, or otherwise, when the syringe
exerts a negative pressure or suction such that the slits open
permitting the withdrawal of a sample of the biological liquid in
order to determine the location of the catheter.
Each one of said radial slits is both longitudinally and
circunferentially offset from the nearest slit so that no single
diametral plane has more than one slit and the dihedral angle
between diametral planes carrying adjacent slits is at least
45.degree., whereby the catheter is given the same rigidity as if
it had no slits, enabling it to make easy penetration without the
problems aforementioned due to bending of same.
These and other objects to be obtained through the use of this
invention will be better understood and more fully perceived in the
following description which refers to the attached drawings of the
preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1, is an elevational view showing the catheter of the present
invention cut into sections and attached to an adapter at its near
end, which is in turn coupled to the tip of a hypodermic
syringe.
FIG. 2, is a detail view of the distal end of the catheter of the
present invention, showing the longitudinal slits to deliver
anesthetic, disposed in different diametral planes and in a
conventional section showing the piece of metallic wire embedded in
the inside of the distal end, which is easily detectable with
X-rays.
FIG. 3, is a cross-sectional view along 3--3 of FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
The improved catheter 11 of the present invention, is composed of a
tube 12 of thermoplastic material having a rounded distal end 13,
bullet shaped to facilitate its penetration through adjacent
tissues until it reaches the epidural space, and having its near
end 14 so made as to permit the attachement of an adapter 15 which
in turn can be attached to a hypodermic syringe 16 partially shown,
by means of which a positive pressure is applied to the anesthetic
contained therein, causing it to pass through the length of tube 12
and discharging it in the epidural space through certain
longitudinal slits 17 placed radially in relation to the
longitudinal axis of tube 12 and so disposed in diametral planes
that the dihedral angle formed between the diametral planes of two
adjacent slits is at least 45.degree. and that furthermore, none of
the said diametral planes contains more than a single slit 17, thus
giving the catheter the same rigidity as if it had no slit
whatever, to permit its ready penetration without the danger of
bending or breaking.
The catheter 11 of the present invention further has embedded in
the distal end 13, thereof as shown in FIG. 2 a piece of metallic
wire 18 which is inert to biological tissues and which does not
engage in ion exchange with the biological liquids and tissues,
being of such a material as stainless steel with low content of
carbon, platinum, gold, alloys of cobalt, chrome and molybdenum,
etc., said metallic portion 18 being readily detectable by means of
X-rays even when catheter 11 is surrounded by bone tissue, as is
usual in cases of epidural anesthesia.
The tube 12 also includes markings 19, 20, 21, which are different
from one onother and spaced along the catheter to show the person
applying the anesthesia the location and penetration of the
catheter and of the slits for delivering anesthetic. This
indication can be further made more precise by means of X-rays,
thereby detecting the position of metallic portion 18.
Once the slots 17 for delivering anesthetic are in the intended
epidural space a negative pressure is applied with the syringe 16
withdrawing a sample of the biological liquid and when the source
of the latter has been determined a positive pressure is applied
upon the anesthetic, delivering it through slits 17 into the
epidural space.
The initial penetration of the catheter 11 is carried out as
described at the beginning by passing it slidingly through a
hypodermic needle, which is done by marking a prior incision or
puncture in the external tissues of the patient, and later
withdrawing this placement needle once the catheter 11 has been
situated in the desired location.
It is important to note that the opening of slits 17, is effected
solely by the application of a positive or negative pressure, thus
preventing the back-flow of fluid through a mere pressure
difference due to carelessness with the resulting complications and
problems.
While, the foregoing description has been drawn to a specific
embodiment of the invention, it will be understood by all those
skilled in the subject matter that changes in form and detail are
encompassed withing the scope and spirit of the invention.
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