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BACKGROUND OF THE INVENTION
The present invention and my copending applications relate generally to
instruments for dilating a body passage to enable draining a fluid through
the passage; and, in particular, the tubular instruments adapted to pass
through the urethra to the urinary bladder for (1) dilating a narrowed
urethra, (2) withdrawing urine, (3) inserting urethral instruments
including retention catheters into the urinary tract or (4) performing
urologic surgery.
The present invention specifically relates to a rigid, hollow stylet for
insertion within a flexible, hollow catheter having an open tip
portion--the stylet cooperates with a filiform to place the catheter in
the bladder. The stylet can also be used without the filiform for
placement of catheters that do not have open tip portions.
By way of background, the size of most urologic instruments including
catheters, filiforms, followers, bougies and sounds is determined by the
outer diameter of the instrument. Although there are both American and
English scales of measurement, the Charriere or French (F) scale is most
frequently used. According to the French scale, the size of a tubular
instrument is determined by multiplying the diameter expressed in
millimeters (mm) by 3. Thus, a diameter of 8 mm is equal to No. 24 F.
Catheters, as defined herein, are hollow, tubular instruments made of
rubber, nylon, silicone, Teflon, woven silk (stiffened by shellac),
plastic or metal that are used for drainage of fluid media, specifically
urine, from the bladder. Many different types are available from a
straight tube for a single insertion to tubes of varying shapes, curves
and diameters for specific situations. All catheters, however, have
similar functions--to provide drainage, to introduce medications and
radiopaque contast media, and to obtain a urine specimen.
Catheters may be nonretentive or retentive. The most frequently used
straight, nonretentive catheters are the Robinson and the whistle-tip
design which are usually made of natural or latex rubber. The Robinson
catheter has a solid rounded tip and may have two, four or six eyes or
holes along its side. The whistle-tip catheter has an open tip portion and
two eyes, one on the side and one at the semirounded angle of the tip.
Robinson catheters have the disadvantage of being nonretentive but are
used for a single insertion such as in the collection of a urine specimen
or in relieving the patient of acute bladder retention.
Another type of nonretentive urethral catheter is the Coude catheter, also
known as the "elbow" or "natural curve" catheter. The term "Coude", of
course, refers only to the curve of the catheter tip, that tip usually
includes a single eye and may taper to a point or have an olive-shaped
enlargement (olive tip). The advantage of this curve is that it can
following the contour of the bulbar and prostatic urethra as it curves
beneath the symphysis pubis and rides over the bladder neck. Coude
catheters are usually made of red rubber, are somewhat stiffer than
Robinson catheters and are often impregnated with small amounts of lead
for radiographic observation.
The most frequently used retentive catheter for draining the bladder is the
Foley type, which comprises two tubes--a larger tube for drainage and a
smaller side tube connected to a balloon that is inflated with a fluid
after the catheter is positioned. The inflated balloon thus prevents the
catheter from slipping out. A Councill catheter is similar to a Foley
catheter, but includes an open tip portion that receives a special stylet
which can be threadably connected to a filiform. The tip of the Foley and
Councill catheter usually includes one or two eyes between the tip and the
balloon. The present invention relates to an improved Councill
catheter-stylet combination in which the filiform and stylet are not
threadably connected.
As stated in my copending application, a catheter can usually be passed
through the urethra without incident. Occasionally, however, particularly
when the lumen of the urethra is narrowed because of disease or when a
large tube such as a cystoscope or a large catheter is to be passed, the
urethra may have to be dilated. This is done by inserting and withdrawing
a series of progressively larger dilation instruments (dilators).
The most common dilator is a solid smooth metal instrument with a curved
tip, called a sound, that looks like a metal catheter. For example, the
Van Buren sound is such a solid metal instrument--but it is not intended
to be left indwelling.
A bougie can also be used. A bougie is a slender, flexible, cylinder solid
instrument having an enlarged tip portion for introduction into the
urethra or other tubular organ, usually for the purpose of calibrating and
dilating a constricted area.
If the passage is severely constricted, use of a filiform and a follower
may be necessary. A filiform is a narrow, solid, somewhat stiff instrument
commonly used to traverse a strictured urethra. Various filiform tips can
be used, such as a straight, spiral or olive tip. The end of the filiform
opposite the tip includes a female threaded portion. The follower, a
semi-flexible catheter or bougie with a male threaded tip, is then
threadably connected to the threaded portion of the filiform to define a
tapered assembly having the appearance of a flexible whip.
The assembly can be guided through the strictured area and followers of an
increasing diameter can be attached to the filiform upon withdrawal of the
follower from the urethra to further dilate the stricture. As the follower
is introduced, the filiform merely coils on itself inside the bladder. The
screw-on filiform may have either a male or female thread and, of course,
the follower must have a corresponding thread to be of use. Frequently the
assembly must be left indwelling, particularly when it is desirable to
dilate the urethra gradually over the course of several days. In that
case, since the filiform is a solid shaft, eyes are provided in the sides
of the catheter follower at the tip end portion to permit the drainage of
urine from the bladder.
In a similar manner, a filiform can be threadably connected to a solid
metal stylet for passage through the urethra. The stylet can be used to
pass a catheter through a strictured urethra. In practice, the solid
stylet is inserted within the catheter so that the threaded tip of the
stylet extends beyond the open tip portion of the catheter, and the stylet
can be threadably connected to the filiform. The filiform, stylet and
catheter are then passed through the urethra to the bladder. Once the tip
of the catheter is in the bladder, a balloon or an inflatable portion near
the tip can be inflated to secure the catheter in position. Thereafter the
filiform-stylet assembly is withdrawn.
Problems frequently arise, however, in the use of a threaded
filiform-follower (or filiform-stylet) assembly. For example, the threaded
connection can break or the follower (or the stylet) can separate from the
filiform after insertion. In that case, it is very difficult to extricate
the filiform from the bladder. Such removal can be performed
endoscopically, or surgery may be required to open the bladder and gain
sufficient access for removal. In addition to this serious disadvantage,
the currently used threaded assembly is nondisposable and must be
sterilized after each use. Moreover, the operation of connecting the
threaded portion of the filiform and the follower or the stylet is awkward
and time consuming.
DESCRIPTION OF THE PRIOR ART
In addition to the previously described urologic instruments, the following
references constitute the closest prior art of which applicant is aware.
U.S. Pat. No. 2,856,934 to Petillo relates to a catheter consisting of a
solid, flexible filiform and hollow, rigid follower. That reference does
not show a hollow filiform or a hollow stylet for urethral catheter
insertion. Moreover, the solid filiform of Petillo increases in diameter
along its length such that a mid-length, the filiform measures 6 F. Since
the hollow, rigid follower will only accommodate a filiform measuring 5 F
or less, the complete length of the solid filiform cannot freely pass
through the follower and the follower cannot pass all the way over the
filiform. According to the present invention, a hollow filiform has a
uniform diameter throughout its length to permit urethral instruments to
slidably pass over the filiform for introduction into or removal from the
urethra while the filiform remains positioned within the urinary tract.
This enables an interchangeability of urological instruments not suggested
by Petillo. Also, the filiform can be removed to leave the retention
catheter in the bladder.
U.S. Pat. No. 3,811,449 to Gravlee et al. discloses a dilating apparatus
which permits the insertion of a medical instrument into a body passage
while the opening to the passage is maintained in a dilated state larger
than the diameter of the instrument. An elongated, solid flexible probe
having a uniform diameter and a rounded insertion tip is inserted into the
passage. A first elongated, flexible, hollow dilator is inserted over the
probe up to the insertion tip of the probe. The solid probe is then
removed and a second elongated, flexible hollow dilator having a slightly
larger internal diameter than the external diameter of the first dilator
is inserted co-extensive over the first dilator. In this manner, dilators
having a successively greater internal diameter are sequentially inserted
over dilators of lesser diameter and the smaller, inner dilators are
removed from the passage until the tissue is stretched to a predetermined
size by a final dilator.
The Gravlee device, however, is designed for use in dilating the cervical
canal. Although Gravlee et al. mention the use of the probe and dilators
to enlarge the urinary tract, that device is not suitable for urethral
insertion and for use with urethral instruments such as a catheter,
cystoscope or urethrotome. First, the probe is solid rather than hollow;
and the external and internal diameters of the probe are large relative to
the filiform of the present invention. Second, the leading ends of the
probe and the dilator are not tapered or narrow enough to serve as a guide
through the strictured urethra.
According to the present invention, it is essential that the filiform be
small or narrow enough to pass within a catheter such as a Councill
catheter, and its stylet. Moreover, the filiform must be narrow and have a
tapered or rounded tip to prevent injury to the urethral mucosa during
passage. Use of an extremely narrow filiform as a guide maintains the
continuity of the urethra when catheters are changed after the damage
urethra has been surgically repaired.
SUMMARY OF THE INVENTION
The present invention relates to the use of elongated filiforms or guides
with slipover instruments and, in particular, to an improved
catheterstylet combination. The device of my copending application
comprises an elongated hollow filiform which is passed through the urethra
to probe, seek and follow the passage. If the urethra is particularly
difficult to traverse, a metal wire, also called a stylet, can be inserted
within the filiform to increase the stiffness of the filiform during
placement. Thereafter, the operator can insert a hollow dilator over the
filiform while the filiform remains within the urethra.
The filiform serves as a guide for the subsequent insertion of instruments
having various diameters into the urinary tract to dilate or calibrate the
urethra. Indeed, the filiform can be used with most followers and sounds
provided that the dilators are hollow through their length to form an
opening slightly larger than the outer diameter of the filiform at the
distal and proximal ends thereof. The hollow filiform also helps prevent
false passages and the curling of the filiform in the urethra by
permitting the operator to remove the wire stylet from the filiform and
check for drainage or urine so that the operator will note when the tip of
the filiform is in the bladder.
The present invention involves an improved catheter-stylet for use with the
above-described filiform. The stylet is particularly suited for use in the
described slipover concept.
Specifically, the elongated, hollow filiform having a tapered insertion tip
is passed through the urethra to the urinary bladder and functions both as
a probe to seek the lumen or opening of the urethra and as a guide so that
a rigid, hollow stylet within a Councill catheter or the like can be
slidably passed over the filiform while the filiform remains in a
stationary position in the urethra and bladder. The stylet and the
filiform can then be removed to leave the catheter within the bladder. If
the urethra is severely constricted, a first elongated, hollow dilator can
be guided over the filiform to dilate or widen the urethra before the
stylet and catheter can be replaced by a second dilator having a larger
outer diameter to further dilate the urethra without removal of the
filiform from the passage.
It follows, therefore, that it is an object of this invention to provide a
device for passage to the bladder through the urethra wherein the device
can be assembled in a simple and efficient manner and disengaged for
separation of one part from the other for easy removal without the danger
of breakage. The egress or aspiration of urine through the filiform
indicates the location of the filiform tip within the bladder. False
passages and curling of the filiform can be prevented because the operator
can determine when the filiform tip enters the bladder. Moreover, the
slipover concept permits a more orderly interaction between urologic
instruments.
It is a related object to provide a hollow stylet for use in combination
with the filiform and a hollow catheter having an open tip portion such as
a Councill catheter wherein easy access can be had for assembly of the
parts in a simple and efficient manner. The stylet can also be used
without the filiform for placement of catheters that do not have open tip
portions including Foley catheters.
These and other objects and advantages of this invention will hereinafter
appear and for purposes of illustration, but not of limitation, in the
accompanying drawings.
BRIEF DESCRIPTION OF THE INVENTION
FIG. 1 is a side view of a flexible catheter passed coaxially over the
stylet and a hollow filiform;
FIG. 2 is a side view of the stylet;
FIG. 3 is a cross-sectional view taken along the line 3--3 of FIG. 1;
FIG. 4 is a schematic view showing a hollow filiform having a tapered tip
passed through the urethra into the bladder;
FIG. 5 is a schematic view showing the catheter and stylet slidably passed
over the filiform; and
FIG. 6 is a schematic view showing the filiform member and stylet
withdrawn, leaving a Councill catheter in position to drain the bladder.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to the use of an elongated, hollow filiform
as a guide for a catheter-stylet assembly. The invention replaces standard
filiform and catheter stylets now available which use a threaded locking
mechanism to connect the filiform to the stylet.
Referring to FIG. 1, the device includes a filiform 10 in the form of an
elongated, hollow, flexible member having a relatively small cross section
with a rounded or tapered end portion 12 on its proximal end 14 to
facilitate insertion through the urethra 16 (see FIG. 4) and to avoid
sharp edges which might traumatize the tissue of the urethra. The filiform
10 can be made into a variety of types, such as a straight member of
uniform cross section or the proximal end 14 can be in the form of a
spiral tip, an olive tip or the like. The filiform is dimensioned to have
a length considerably greater than the distance between the bladder 18 and
the external opening of the urethra.
In one embodiment, the filiform is 27 inches long and 4 F in diameter.
Because of this small diameter, the filiform can be used to pass through
the urethra and into the bladder. As indicated, the filiform is hollow and
can be considered a filiform catheter since an opening 20 provide a
passage for the drainage of fluid, such as urine from the bladder, and the
injection of a radiopaque medium to determine the position of the filiform
in the urinary tract. In addition, a metal wire or stylet 22 can be
inserted within the filiform to provide the necessary stiffness and
tactile sensation for passage of the hollow filiform through the urethra.
The present device also includes a stylet 24 and a catheter 26 in the form
of elongated, hollow members, each having a passage 28 and 30,
respectively, extending continuously therethrough. As used herein, the
term "wire stylet" refers to the stylet 22 that passes within the filiform
10. The term "stylet", on the other hand, refers to the stylet 24 that is
substantially larger in cross-section than the stylet 22 and which passes
within the catheter 26.
Referring to FIG. 2, the stylet 24 is preferably made of a corrosion
resistant metal and has a curved and tapered proximal end portion 32 for
insertion through the catheter. An annular projection or bulbous portion
34 about the proximal end portion 32 expands the elastic inner wall of the
catheter 26 to hold the stylet 24 within the catheter.
The distal end 36 of the stylet 24 includes a gripping portion 38 that is
enlarged relative to the shaft 40 of the stylet. The gripping portion 38
is in the form of a cylinder with a flat surface 42 and a rounded surface
44 for holding by the thumb and forefinger of the user. Between the shaft
40 and the gripping portion 38 is a barrel-shaped portion 46 having a
diameter slightly less than the inner diameter of the catheter to allow
the distal end 48 of the catheter to rest over the barrel-shaped portion
46 and against the gripping portion 38. Annular rings 50 about the
barrel-shaped portion assist in holding the distal end of the catheter in
a fixed position on the stylet.
It can be seen that the gripping portion also functions as a means for
preventing the proximal end portion 32 of the stylet 24 from passing
beyond the proximal end portion 52 of the catheter 26; and that the length
of the shaft is approximately equal to the length of the catheter. The
catheter 26 has an opening in the proximal end portion 52 and includes at
least one opening 54 through the side wall of the proximal end 52 to
enable urine to drain from the bladder into the catheter. The catheter,
like the stylet 24, is dimensioned to have a length slightly greater than
the distance between the bladder and the entrance to the urethra but less
than the length of the filiform 10. The proximal end 52 of the catheter
can be formed to extend at an angle from the body portion 56, like a Coude
catheter to facilitate insertion through the urethra; or the catheter can
comrise a straight semi-flexible member.
In conventional practice, the catheter is generally made available in
various cross-sectional dimensions to permit utilization of the maximum
size catheter in the event that the passage through the urethra is very
tight and to enable use of catheters of increasing cross section for
replacement of one with another over a period of time as the obstruction
through the urethra is relieved.
As described, the stylet 24 can be formed of a corrosion resistant, inert
metal of the type used for surgical instruments to enable repeated use
with sterilization procedures after each use. It is preferred to form the
filiform of a plastic material as a single use, aseptic, disposable item.
An important concept of the invention resides in the ability of the hollow
stylet 24 to freely slide over the filiform through the urethra and
provide for removal of the filiform and the stylet while the catheter 26
remains in the passage. Equally important is the ability of the stylet 24
to move within the catheter 26. But the stylet tip cannot pass beyond the
tip of the catheter and the catheter-stylet assembly must function as a
unit during insertion with the stylet securely holding the catheter
thereon. The interaction of these components can be more clearly seen in
FIG. 3.
In use, the hollow filiform 10 is directed through the urethra until the
tapered end portion 12 enters the bladder, as shown in FIG. 4. The
filiform may coil on itself upon entering the bladder, and entry into the
bladder is usually indicated by the egress or aspiration of urine through
the filiform. If the urethra is particularly difficult to traverse, the
wire stylet 22 can be inserted within the filiform to increase the
stiffness of the filiform during placement.
Next, the stylet 24, which has been inserted within the catheter 26 is
slidably passed coaxially over the filiform and into the urethra.
The hollow filiform 10 of the present invention offers several advantages
and safety features over the solid filiforms of the prior art. For
example, by observing the egress of urine from the filiform catheter once
the wire stylet 22 is removed, one can safely conclude that the filiform
tip is properly positioned in the bladder and the filiform is not in a
false passage.
If the volume of effluent is insufficient, urine can be aspirated through
the filiform with a syringe. Moreover, a radiograph can be taken to
determine the position of the filiform tip by injecting a radiopaque
contrast medium through the filiform. That was not possible with the
filiforms of the prior art.
In the event that the stylet 24 and catheter cannot be advanced over the
filiform for passage through the urethra, a hollow dilator of smaller
cross section can be substituted. Once penetration has been established
and the passage through the urethra is dilated the stylet and catheter can
be substituted by removing the dilator without removal of the filiform and
by passing the catheter-stylet assembly over the filiform and through the
urethra into the bladder (see FIG. 4).
Therefore, the operation of inserting an indwelling catheter (such as a
Councill catheter) involves (1) inserting a filiform catheter 10 through
the urethra into the bladder, (2) dilating the urethra as necessary, (3)
removing the dilator used and leaving the filiform in place, (4) inserting
the stylet 24 into an open tip catheter, (5) slipping the catheter-stylet
assembly over the filiform 10 into the bladder, (6) inflating a balloon 58
(see FIG. 6) of the catheter through a side port 60 (See FIG. 1) and (7)
removing the filiform and the stylet. It will be noted that the balloon 58
is inflated in a conventional manner by injecting a fluid into the side
port 60 once the proximal end portion 52 of the catheter is within the
bladder. The fluid passes through a conduit 62 (FIG. 3) within the
catheter to inflate the balloon.
Many other urologic instruments that are currently available can also be
used with this device and method without modification. For example, a
cystoscope with a direct vision obturator in place and without the lens
will easily slip over the filiform. A cystoscope is an instrument
specifically designed for passing through the urethra into the bladder to
permit inspection of the interior of that organ. At the end of the
cystoscope is an electric bulb or a fiberoptic lens system that
illuminates the bladder interior, and a channel is provided to pass an
irrigating fluid to distend the bladder. By means of special lenses the
bladder mucosa can be examined for inflammation, calculi or tumors. A
ureteral catheter can then be passed through the cystoscope into the
bladder and beyond the bladder into the ureters and kidneys. In this
manner, samples of urine can be obtained for diagnostic purposes of
radiopaque fluids can be injected into the ureters for X-rays of the upper
urinary tract.
In addition, the performance of urologic surgery can be facilitated by use
of the present invention. It should be pointed out that most urethral
strictures are successfully treated by gradual urethral dilation using
filiforms and followers or sounds of increasing size. Occasionally,
however, very tight strictures of a fibrous nature require transurethral
incision. For this purpose a urethrotome, which comprises a metal
instrument having a small knife blade hidden within its tip, is frequently
used. The blade can be advanced or withdrawn and as the blade is
manipulated, the roof of the urethra is incised. Following the division of
the stricture, a retention catheter is introduced. The device of the
present invention enables the urethrotome to be inserted over the hollow
filiform and subsequently when the urethrotome is removed, the filiform
will remain as a guide to place the stylet and Councill catheter assembly
without losing the course of the urethra.
It will be apparent from the foregoing that a considerable improvement is
provided in the ease and safety of passing the catheter and the stylet
over a filiform as compared to the awkward and potentially dangerous
procedure of threadably connecting the filiform to the stylet. In
addition, placement of the elongated filiform allows dilatation by a
hollow plastic follower or a hollow metal sound, cystoscopic examination,
direct view urethrotomy and the subsequent placement of a Councill
catheter or the like.
It will be understood that changes may be made in the details of
construction, arrangement and operation, without departing from the spirit
of the present invention, especially as defined in the following claims.
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