Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION:
Retractable Needle
FIELD OF THE INVENTION
The present invention relates to a retractable needle.
BACKGROUND OF THE INVENTION
A retractable needle can be used to deliver an anaesthetic block to a
particular nerve.
1 o In order to effectively deliver the anaesthetic block, the needle is
placed in a given body
cavity close to the nerves. This can be accomplished either anatomically by
advancing into a
certain position or via the use of an electrical pulse through the needle that
is weak enough to
only transmit to the nerve when the needle is in close proximity. To get close
to the nerve or
nerves to be blocked, the needle must first be advanced through tough,
resilient tissue. This
requires that the needle have a sharp pointed tip. After the needle has passed
through the
initial layer of tough resilient tissues, it must then pass though a layer of
loose fat, connective
of tissue, blood vessels and nerves. As the tip of the needle is pointed,
there is a danger that
the block needle might pass through and traumatize blood vessels or nerves. An
even greater
danger is that the needle will pass into or through a critical body part such
as an eye.
2 0 The concept of having a retractable needle is known in the art, as
illustrated by
United States Patent 5,013,304 (Russell et al 1991) and United States Patent
5,456,668
(Ogle 1995). Both the Russell et al and Ogle references disclose syringe
bodies having an
axial slot. A needle is attached to a manually adjustable sliding member,
which engages
the slot. When the sliding member is slid in a first direction, the needle is
extended from
2 5 the syringe body. When the sliding member is slid in a second direction,
the needle is
retracted within the syringe body. The retractable needles of Russell et al
and Ogle were
not developed as Block Needles and, as such, are not particularly suited for
block needle
applications.
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SUMMARY OF THE llVVENTION
What is required is a retractable needle that is better suited to block needle
applications and other similar application in which the key concern is tissue
damage.
According to a first aspect of the invention, there is provided a retractable
needle.
The retractable needle has an elongated tubular needle housing. The housing a
longitudinal axis and a slot. A needle is disposed within the housing. A
manually
adjustable sliding member engages the slot in the housing. The sliding member
is secured
to the needle, such that when the sliding member is slid along the slot in a
first direction,
l0 the needle assumes an extended position extended from the housing and when
the sliding
member is slid along the slot in a second direction, the needle assumes a
retracted position
retracted within the housing. The slot has a first end at a first axial
position relative to the
longitudinal axis, a second end at a second axial position relative to the
longitudinal axis.
The second end is axially and circumferentially spaced from the first end, and
a transition
portion that extends around the circumference of the housing at an angle
connects the first
end and the second end.
Beneficial results may be obtained by providing the slot with a first portion
at the
first end extending transverse to the longitudinal axis, the first portion
being adapted to
2 0 lock the needle in the extended position and a second portion at the
second end extending
transverse to the longitudinal axis, the second portion being adapted to lock
the needle in
the retracted position.
Even more beneficial result may be obtained by providing the housing with an
2 5 attachment end and a remote end, the needle extending from the remote end,
and the
attachment end being adapted for connection to a syringe.
BRIEF DESCRIPTION OF THE DRAWINGS
3 0 These and other features of the invention will become more apparent from
the
following description in which reference is made to the appended drawings, the
drawings are
for the purpose of illustration only and are not intended to in any way limit
the scope of the
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invention to the particular embodiment or embodiments shown, wherein:
FIGURE 1 is a side elevation view, in section, of a block needle constructed
in
accordance with the teachings of the invention;
FIGURE 2 is a side elevation view, in section of the block needle illustrated
in
FIGURE 1, with the needle in the extended position;
FIGURE 3 is a side elevation view, in section, of the block needle illustrated
in
FIGURE 1, detached from a syringe in the extended position;
FIGURE 4 is a side elevation view, in section, of the block needle illustrated
in
FIGURE 1, detached from a syringe in the retracted position; and
FIGURE 5 is an end elevation view, in section of the block needle illustrated
in
FIGURE 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment, a retractable block needle generally identified by
reference numeral 10, will now be described with reference to FIGURES 1
through 5.
Structure and Relationship of Parts:
Referring to FIGURE 1, there is shown a retractable needle 10, comprising an
2 0 elongated tubular needle housing 12. Needle housing 12 has a longitudinal
axis 14, a slot
16, and a needle 18 disposed within housing 12. The position of needle 18 is
controlled
by a manually adjustable sliding member 20 that engages slot 16 in housing 12.
Sliding
member 20 is secured to needle 18, such that, refernng to FIGURE 4, when
sliding
member 20 is slid along slot 16 in a first direction 22, needle 18 assumes an
extended
2 5 position extended from housing 12, and, referring to FIGURE 3, when
sliding member 20
is slid along slot 16 in a second direction 24, needle 18 assumes a retracted
position
retracted within housing 12. Referring now to FIGURE 5, slot 1 b has a first
end 26 at a
first axial position 28 relative to longitudinal axis 14, and a second end 30
at a second
axial position 32 relative to the longitudinal axis. Second end 30 is axially
and
3 0 circumferentially spaced from first end 26, and a transition portion 34
extends around the
circumference of housing 12 at an angle to connect first end 26 and second end
30. While
the angled nature of transition portion 34 is not apparent from FIGURE 5, it
can be seen
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in, for example, FIGURE 4.
Referring now to FIGURE 3, retractable needle 10 is shown not connected to a
syringe 11. Slot 16 has a first portion 36 at first end 26 extending
transverse to
longitudinal axis 14, where first portion 36 is adapted to lock needle 18 in
the extended
position as shown in FIGURE 4. A second portion 3$ at second end 30 extends
transverse to longitudinal axis 14, where second portion 38 is adapted to lock
needle 18 in
the retracted position as shown in FIGURE 3.
Referring now to FIGURE 1, housing 12 has an attachment end 40 and a remote
end 42. Needle 18 extends from remote end 42, or is slightly retracted within,
and
attachment end 40 is adapted for connection to syringe 11. It will be
understood that
syringe 11 and block needle 10 could be formed from one body, in which case
attachment
end 40 would not be required. It will be appreciated that needle 18 can come
of varying
lengths and sizes.
Operation:
Needle 18 is moved to the extended position shown in FIGURE 2 by locking
sliding
member 20 into second portion 38. Block needle 10 is then advanced through
layers of tissue
2 o and fat until the desired location is reached. Once the sharpness of
needle 18 is no longer
needed to penetrate tissue, or once there is a risk of damaging a vessel, a
nerve, or other such
areas, needle 18 is retracted into the retracted position shown in FIGURE 1 by
locking
sliding member 20 in first portion 36. Syringe 11 is then used in the desired
application.
2 5 It will also be appreciated that housing 12 can be of a non-conductive
material and
needle 18 can be of a conductive material with a power supply for supplying a
low
amperage current to needle 18. The low amperage current supplied to needle 18
can be
used to localize nerves in which it is placed.
3 0 In this patent document, the word "comprising" is used in its non-limiting
sense to
mean that items following the word are included, but items not specifically
mentioned are not
excluded. A reference to an element by the indefinite article "a" does not
exclude the
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possibility that more than one of the element is present, unless the context
clearly requires that
there be one and only one of the elements.
It will be apparent to one skilled in the art that modifications may be made
to the
illustrated embodiment without departing from the spirit and scope of the
invention as
hereinafter defined in the Claims.
