Surgical needle abstract
The invention provides a catheter placement apparatus for use in
inserting a catheter to a preferred depth, the device comprising
a surgical needle with a longitudinal window through which a catheter
inserted into the needle can be viewed, and a catheter having a
colored patch of the same length as the window and a series of spaced,
visually distinct markings, proximal to the patch. The position
of the catheter can be accurately located by aligning the colored
patch with the window and then inserting the catheter until at least
one mark appears in the window, recording the distance of a mark
from the surface of the skin and using this recorded distance to
relocate the catheter, if necessary.
Surgical needle claims
I claim:
1. Apparatus for use in accurately locating a catheter with respect
to the outer surface of a patient's skin, the apparatus comprising:
a hollow surgical needle having an elongate stem portion of uniform
inner and outer diameters defining a sharpened leading end and an
opening at that end, a window formed through a portion of said stem
with means for providing airtight separation between an interior
of said stem visible through said window and an exterior of said
stem, said window being of sufficient longitudinal extent that a
part of this portion will be inserted into the patient's skin when
the needle is inserted to a required depth;
a flexible tubular catheter adapted to be slidably inserted in
the hollow surgical needle and moveable through the needle to project
out beyond said opening in the leading end of the needle, the catheter
including a leading end and markings spaced along its length including
a first marking which cooperates with said window to indicate alignment
of said leading edge of said needle and said leading edge of said
catheter;
whereby said needles can be inserted to a required depth and the
leading end of the catheter can be inserted into and through the
needle to a desired position with said first marking and said location
indicating said alignment and with the markings being visible through
the window, the markings being used as a guide to indicate the amount
of catheter entered into the needle and so that one of the markings
visible through the window can be used as a reference point to permit
the catheter to be located in the same position relative to the
skin surface after the needle has been removed.
2. Apparatus as claimed in claim 1 wherein the window is a longitudinal
slot formed in the stem portion and said means for providing airtight
separation comprises a thin transparent material, covering the slot
in airtight engagement.
3. Apparatus as claimed in claim 1 wherein the window is a longitudinal
slot formed in said stem portion and said means for providing airtight
separation comprises a transparent material fitted in the slot so
that the outer surface of the window is substantially flush with
the surface of the stem portion with said material joined to said
stem in airtight engagement.
4. Apparatus as claimed in claim 2 wherein the catheter has a coloured
patch comprising said first marking which is of substantially the
same length as the longitudinal slot, the patch being positioned
on the catheter so that when the catheter is inserted into the needle,
with all of the patch showing in the window, the catheter has its
end at the end of the needle.
5. Apparatus as claimed in claim 3 wherein the catheter has a coloured
patch comprising said first marking which is of substantially the
same length as the longitudinal slot, the patch being positioned
on the catheter so that when the catheter is inserted into the needle,
with all of the patch showing in the window, the catheter has its
end at the end of the needle.
6. Apparatus as claimed in claim 4 wherein said catheter includes
a series of spaced markings along the length of the catheter extending
from the proximal end of the coloured patch towards the proximal
end of the catheter, each marking being visually distinguishable
from the others.
7. Apparatus as claimed in claim 2 wherein the transparent material
is a thin-walled tube of heat-shrinkable plastic.
8. Apparatus as claimed in claim 7 wherein the plastic is polytetrafluoethylene.
9. Apparatus for use in accurately locating a catheter with respect
to the outer surface of a patient's skin, the apparatus comprising:
a hollow surgical needle having an elongate stem portion of uniform
inner and outer diameters defining a wall terminating in a sharpened
leading end and an opening at that end, the stem having a portion
of its wall removed to define a longitudinal slot therein, a thin-walled
transparent tube being securely fitted over the stem portion, the
portion of the tube over the slot defining, with the slot, a window
by which the interior of the stem portion can be seen, the window
being of sufficient length that when the stem of the needle is inserted
into the patient's skin a portion of the window remains outside
the skin surface; said tube bonded to said stem to provide airtight
separation between an interior of said stem and an exterior of said
stem;
a flexible tubular catheter adapted to be slidably inserted in
the hollow surgical needle and moveable through the needle to project
out beyond said opening in the leading end of the needle, the catheter
having a leading end, a coloured patch along its length of the same
length as the slot, and a series of different visually distinguishable
markings spaced along the catheter from the proximal end of the
coloured patch towards the proximal end of the catheter; said patch
disposed on said catheter for said catheter leading end to be aligned
with said stem leading end when said patch on said catheter is inserted
into said needle with said patch filling said window;
whereby, after the needle has been inserted to a required depth
the leading end of the catheter can be inserted into and through
the needle to a desired position, said desired position being recognized
when the coloured patch is aligned with the slot as viewed through
the window, and the visually distinguishable markings being used
to indicate the amount of catheter subsequently entered into the
skin so that, a mark proximal to the proximal end of the coloured
patch can be viewed through the window and used as a reference point
to permit the catheter to be located in the same position relative
to the skin surface after the needle has been removed.
10. Apparatus according to claim 1 wherein said catheter is formed
of polytetrafluoroethylene.
11. Apparatus according to claim 9 wherein said catheter is formed
of polytetrafluoroethylene.
12. Apparatus according to claim 1 wherein said markings are visually
distinctive.
13. A method of inserting a catheter into a peridural space of
a patient's spinal area using a hollow surgical needle having an
elongate stem with an elongate window formed therein; means for
indicating a pressure drop within said needle; a catheter sized
to be slidably inserted in said needle and moveable therethrough
to project beyond the needle opening, said needle having markings
spaced along its length including a first marking cooperating with
said window to indicate alignment of a free end of said catheter
with said needle opening; said method comprising the steps of:
(a) inserting said needle into said patient with said needle opening
directed toward an anticipated site of said peridural space;
(b) advancing said needle opening toward said anticipated site
until said means indicates a pressure drop within said needle;
(c) inserting said catheter into said needle and advancing said
free end of said catheter toward said needle opening until said
first marking and said window cooperate to indicate alignment of
said free end with said needle opening;
(d) advancing said free end past said needle opening by a desired
amount;
(e) noting a distance between said patient's skin and a selected
marking on said catheter;
(f) withdrawing said needle while maintaining said catheter within
said patient;
(g) aligning said catheter within said patient until said selected
marking is spaced from said skin equal to said noted distance.
Surgical needle description
This invention relates to a catheter placement apparatus having
a catheter which can be inserted to a preferred depth in medical
procedures such as providing peridural block injections.
It is known that in such medical procedures, the leading end of
the catheter should be confined to a predetermined depth. For instance,
in peridural block injections the catheter should be confined to
the peridural space adjacent the spine without bending the catheter
excessively which would collapse the catheter locally. It is therefore
important that the catheter be inserted and maintained at a controlled
depth.
For the purposes of describing the invention and to exemplify its
use, this description will be concerned with catheter placement
in peridural block injections.
Present catheter placement apparatus include an apparatus having
a surgical needle and a catheter which can be moved through the
needle into position. In peridural block injections, because the
peridural space has a negative pressure, a droplet of water can
be placed at the inlet end of the needle so that when the needle
is inserted into the peridural space, the droplet of water is drawn
down the needle. This water movement indicates that the needle has
reached the preferred depth. The catheter is then slid inwardly
through the needle until a mark on the catheter reaches the outer
end of the needle. The mark is positioned to indicate that the leading
end of the catheter is about to pass out of the open tip of the
needle. Consequently, the catheter can then be slid a small distance
further inwardly in order to have a positive displacement into the
peridural space. Next the needle is withdrawn over the catheter
leaving the catheter inserted. The catheter tends to move when the
needle is removed and at that point, there is no way of checking
that the catheter is still properly inserted in the peridural space.
If the catheter has moved, it is very difficult to correct the position
of the catheter without forcing the leading end of the catheter
out of the peridural space or bending the catheter to the extent
of collapsing it locally.
It is the purpose of the present invention to provide a catheter
placement apparatus which will enable the operator to check that
a catheter has been properly placed after the needle has been withdrawn.
Accordingly, a catheter placement apparatus is devised which comprises
a catheter having a series of markings thereon, in combination with
a surgical needle through which the catheter can be inserted and
which includes a window for viewing the markings on the catheter
to enable the operator, while the needle is in place, to note a
reference point on the catheter relative to the patient's outer
skin for ensuring that the desired placement has been maintained
after the needle has been removed.
In a preferred embodiment of the invention the needle is covered
with a heat shrinkable transparent plastic and the catheter has
a coloured patch which fills the slot when the catheter tip is at
the needle tip, and when the catheter is inserted further the edge
of the patch appears, then the series of spaced markings.
The invention will be better understood with reference to the drawings,
in which:
FIG. 1 is a perspective view of portions of a surgical needle and
a catheter forming parts of a preferred embodiment of a catheter
placement apparatus according to the invention;
FIG. 2 is a sectional plan view of the relevant portion of a patient's
back showing the use of the placement apparatus for peridural block
injections;
FIG. 3 is a view similar to FIG. 2 and further illustrating the
use of the placement apparatus after removal of the surgical needle;
and
FIG. 4 is a view similar to FIG. 1 of an alternative embodiment
of placement apparatus according to the invention.
Reference is made initially to FIG. 1. The preferred embodiment
of the present invention includes a surgical needle 20 and a flexible
catheter 21 which can be slidably inserted into the needle as indicated.
The needle 20 has a head portion 22 and an elongated hollow stem
portion 24 of uniform inner and outer diameters. A leading end 26
of the needle 20 is formed to provide a sharp edge around an outlet
27 and a longitudinal slot 28 is formed in the stem portion 24.
The slot is covered by a thin-walled transparent polytetrafluoroethylene
(PTFE) tube 29 which is heat shrunk over the stem portion 24 of
the needle 20. This tube effectively forms a window 30 over the
slot 28. Although the thickness of the tube increases the effective
diameter of the stem portion 24 the tube 29 is so thin that it
does not appreciably increase the overall diameter of the needle
20. Also because the tube is of PTFE, the surface friction of the
needle is reduced to facilitate insertion.
The preferred embodiment of the present invention also includes
the thin-walled hollow catheter 21 made of inert, flexible, polytetrafluoroethylene
(PTFE). The catheter 21 is substantially of uniform inner and outer
diameters throughout its length, its outer diameter being smaller
than the inner diameter of the surgical needle 20 to facilitate
passage of the catheter 21 through the needle 20. The catheter is
coloured with a black patch 32 which is the same length as the longitudinal
slot so that, when a leading end 33 of the catheter is inserted
adjacent the leading end 26 of the needle 20 the black portion
32 is coincident with the longitudinal slot 28 and can be viewed
through the window 30. Circular bands 31 are also provided on the
catheter spaced 1 cm. along the catheter between the proximal end
and the black patch 32. Each band is distinguished from other bands
by its colour. The patch and the bands 31 are marked on the catheter
21 using non-reactive vegetable dyes.
Reference is now made to FIG. 2 which shows the preferred embodiment
of the catheter placement apparatus inserted in a patient's back
during catheter placement procedure. For effective results, it is
intended that the leading end 33 of the catheter 21 be located in
the peridural space 34 adjacent the spinal area 36. If advanced
too far, the catheter 21 may either leave the peridural space 34
and go into the outer area 38 or become twisted and bent thereby
restricting passage through the catheter. This is undesirable because
it reduces the effectiveness of the injection. To locate the catheter
21 a droplet of water is first placed in the head portion 22 of
the needle 20 just prior to insertion. Next the needle 20 is inserted
through the patient's back in the area of the lower spine until
the tip of the needle enters the peridural space 34. Because this
space has a negative pressure, the droplet of water is drawn down
the stem portion 24 of the needle 20 thereby indicating the position
of the needle tip. Once the needle 20 is properly located in the
peridural space 34 part of the window 30 will be visible outside
the patient's skin 40 depending on the amount of flesh through which
the needle has had to pass. The catheter 21 is then slid through
the needle 20 until the black portion 32 coincides with the longitudinal
slot 28 thus indicating to the operator that the leading end 33
of the catheter 21 has reached the end of the needle 20. The catheter
is then advanced a short distance to ensure a positive displacement
of the end 33 into the peridural space 34. When this occurs the
proximal end 42 of the black portion will be visible through the
window 30 with one or more of the circular bands 31. Of the bands
31 visible in the window 30 the colour and the distance of the
band nearest to the patient's skin 40 is noted. The needle 20 is
withdrawn by sliding it along and off the catheter 21 leaving the
catheter in place as shown in FIG. 3. Some movement of the catheter
is inevitable. However, the catheter position may be checked using
the position of the coloured band noted earlier in the window 30.
The catheter is moved until the same band is positioned the same
distance from the skin 40 when it was viewed in the needle window
30. (See FIG. 3) The coloured band and its position relative to
the skin 40 can be recorded for later reference to ensure that the
catheter remains in the proper location throughout the injection
period.
It will be appreciated from the foregoing that the invention can
take many forms consistent with utilizing a viewing window in the
surgical needle used for insertion and a series of marks on the
catheter.
In an alternative embodiment shown in FIG. 4 and in which like
numerals denote like parts with the suffix "a" added,
the slot 28a could be filled by a transparent material, such as
plastic, forming a window 30a which lies flush with the stem portion
so that the stem diameter remains substantially unchanged. Also
the black patch may be replaced by more bands of different colours.
However the black patch gives a clear and rapid indication when
the window is filled that the catheter end has reached the end of
the needle and for these reasons is preferred.
Other transparent material could be used insted of PTFE for the
shrink-wrapping and the catheter black patch may be any colour which,
when viewed through the window, indicates that the catheter's leading
end has reached the end of the needle. Other forms of bands 31 can
be utilized. For instance, spaced marks of increasing width, or
a series of spaced marks consisting of one or more encircling lines,
each mark containing a number of lines one greater than the mark
before it.
These variations are typical of alternative embodiments of the
invention which fall within the scope of the invention described
and claimed. |