Note: Descriptions are shown in the official language in which they were submitted.
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Safety Stylet For Intravenous Catheter Insertion
STATEMENT OF INDUSTRIAL UTILITY
The present invention relates to an intravenous
catheter insertion device having a retractable needle
for rendering the needle safely out of exposure
immediately after use of the device. The invention is
useful in the practice of medicine for improving
safety from the danger of needle pricks after the
intended use of the device in inserting an intravenous
catheter.
BACKGROUND
Intravenous catheters are employed in the
practice of medicine for intravenous administration of
fluids, such as hydrating solutions, medications,
blood products, and nutrients, to a patient. An
intravenous catheter ordinarily includes a flexible
tube, or cannula, having a tip that is positioned
within a blood vessel of the patient. The cannula
extends from the tip to a location external to the
body of the patient. A connection hub is attached to
the external end of the cannula for connection to
external apparatus to facilitate intravenous therapy.
Usually, the connection hub is attached to tubing for
delivery of parenteral fluids from a source of fluid.
The tubing may have an injection port with an anti-
coagulant reservoir (e.g. a heparin lock) for periodic
administration of medication, for example.
Prior to insertion into a patient, an intravenous
catheter is provided as a part of a trocar. The
trocar further includes a stylet having a needle. The
needle extends from the forward end of the stylet and
through the connection hub and catheter cannula, which
is supported as a sleeve over the needle. The
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connection hub may be removably engaged with the
forward end of the stylet. The tip of the needle when
the cannula is positioned thereon, extends beyond the insertion end of the
cannula.
In positioning the tip of the catheter within a
blood vessel of the patient, a doctor or other medical
personnel grasps the body of the stylet with one hand
and pierces the skin of the patient with the needle to
locate the tip of the cannula within a desired blood
vessel. It should be apparent that the skin of the
patient is typically pierced at a low angle to the
plane of the skin. In use of the catheter insertion
device, the device is usually gripped for insertion in
an overhand manner, wherein the forward end of the
stylet is held between the thumb and a finger of the
doctor's dominant hand, such that the rear of the
stylet extends toward the palm. The needle, bearing
the catheter cannula, is then guided through the skin
of the patient and into the desired blood vessel.
Correct positioning of the tip of the needle
within the desired blood vessel is usually indicated
by a "blood return", in which the blood pressure
within the blood vessel forces a small amount of blood
to flow through a cylindrical capillary between the
needle and the cannula of the catheter. After a blood
return is observed, the stylet is withdrawn while the
doctor uses the other hand to apply light pressure
upon the catheter, so that the needle can be withdrawn
from within the cannula while the cannula remains in
place within the blood vessel.
After the stylet is withdrawn, the doctor =
normally tapes the catheter in position at the
insertion site prior to attaching an intravenous tube
or hydraulic lock to the connection hub. Of course,
in order to tape the catheter and to connect the
desired apparatus to the connection hub, the doctor
must put down the stylet to gain a free hand. 'I'hus,
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the contaminated needle of the stylet remains an
exposed sharp hazard until the doctor has finished
attending to the patient and can then properly dispose
of the stylet. Other health care workers in the
vicinity may not be aware of the exposed contaminated
needle, and could be accidentally pricked, if the
needle is contacted. Additionally, the doctor may be
accidentally pricked with the needle during disposal
thereof. In the past, such accidental needle sticks
were considered to be a routine occupational
inconvenience. Now, such occurrences are recognized
as a vector for lethal illnesses, including hepatitis-
B and the Human Immune Virus (HIV), which is
associated with Acquired Immune Deficiency Syndrome
(AIDS).
It would be desirable to provide an apparatus or
stylet for catheter insertion that could be rendered
safe immediately after withdrawal from a patient.
Previous attempts to provide a catheter insertion
apparatus which renders the needle safe from
accidental pricks after use, have included stylets
with slidable locking sleeves thereon for surrounding
the needle after use. Because such a safety feature
is most desirably activated when the doctor has only
one free hand, activation of such sliding or
telescoping sleeves have been difficult. Hence, it
would be desirable to provide a catheter stylet that
could quickly prevent the needle from being a hazard
by use of a simple, natural movement of one hand, and
requiring minimal dexterity.
= Furthermore, it would be desirable to provide a
catheter insertion apparatus that provides a non-
distracting, yet immediate and readily discernible
tactile or audible confirmation that the needle is
encased so as not to present a hazard that can prick a
health care worker or one responsible for disposal of
used needles.
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rr
$VbIIdARY OF TSE INVSNTI9I~T
In accordance with the present invention, an
apparatus or device for insertion of a catheter is
provided. The device has a housing with a needle
extending"from the front of the housing. A spring is
~. FY
positioned within the housing for exerting a force
upontheõneedle, when extended, to urge the needle
into the housing. The force exerted by the spring on
the needle is counteracted by a needle retaining
member;" which releasably holds the needle in its
extended position from the housing. An actuating
member is positioned within the housing and is
operative to release the needle retaining member in
response to a predetermined force applied to the
actuating member. The actuating member protrudes from
the rear of the housing to provide a plunger for
moving the actuating member within the housing. The
release of the needle retaining member is effected by
pressing the plunger against the palm of the hand
while maintaining the same grip upon the device as
used during catheter insertion.
In one aspect, the invention provides an apparatus
for intravenous catheter insertion, the apparatus having
a housing with a front end formed to mate with a catheter
hub and provided with a needle extending from the front
end of the housing for supporting and guiding a catheter
cannula into a blood vessel. A spring is provided within
the housing for exerting a force upon the needle to urge
the needle into the housing and a needle retaining member
is provided for releasably holding the needle in its
extended position from the housing against the force of
the spring. An actuating member is positioned within the
housing and has a plunger end held by means for retaining
the actuating member at a first defined position
extending beyond the rear end of the housing, the
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actuating member being released by the means for
retaining the actuating member and movable to a second
defined position in response to a predetermined pressure
upon the plunger end to release the actuating member
from the first position, whereby the needle is forced
into the housing by the spring. The actuating member
has a compartment with an open forward end for receiving
and containing the needle after the needle is forced
into the housing by the spring.
Other new and useful features of the invention will
be apparent from the description set forth hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing summary, as well as the following
detailed description, will be best understood when read
in conjunction with the attached drawings in which:
FIG. 1 is a sectional view of the catheter
insertion device of the present invention;
FIG. 2A is an enlarged fragmentary sectional view
of the rear end of the catheter insertion device of
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FIG. 1;
FIG. 3 is an exploded perspective view of a
needle retaining mechanism for holding a spring-loaded
needle within the catheter insertion device of FIG. 1;
and
FIG. 4 is a perspective view of an alternative
embodiment of the needle retaining member for use in
the catheter insertion device of FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, there is shown the
apparatus or device of the present invention generally
designated 10. The device 10 may be referred to as a
trocar or stylet. The device includes a hollow
housing of varying cross section 12 with a needle 14
extending therefrom with a catheter 16 and a
protective hollow cap 18 encircling the needle. The
needle 14 extends outwardly from the front end of the
housing. The catheter 16 includes a tapered flexible
cannula 20 positioned as a sleeve over the needle 14.
The tip or front end of the needle 14 extends beyond
the front end of the cannula. The tip of the needle
14 is preferably tapered to prevent coring of tissue
when the needle is inserted into a patient. The
catheter 16 further includes a connection hub 22
attached to the distal or rear end of the cannula 20.
The front end of the housing 12 includes a front
alignment member 24 that is contoured to mate with the
connection hub 22 and removably hold the catheter 16
and its associated hub 22 in frictional engagement
therewith before the catheter is inserted for use in
the patient.
= Finger ridges, generally designated 26a and 26b,
are formed on opposite sides of the forward end 25 of
the housing 12. The ridges 26a and 26b are contoured
to allow a doctor or other health care professional to
comfortably grip the device 10 near the forward end
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thereof, and preferably between the thumb and
forefinger of the doctor's preferred hand for use of
such devices. Ridges 28a and 28b are formed upon the '
forward end 25 of the housing, in front of the finger
ridges 26a and 26b, for retaining the cap 18 upon the
device, preferably in snap-fit engagement with
retaining groove 30 formed on the interior surface of
the hollow cap 18. The cap 18 extends forward from
the front end 25 of the housing to surround and
protect the needle 14 prior to use of the device 10.
Referring now to FIG. 2A, the front or forward
end of the housing 12 is shown in greater detail. The
front end 25 of the housing has an axial bore 32
formed therein. The axial bore 32 is sized to receive
the front alignment member 24. The front alignment
member 24 is firmly engaged within the forward portion
of the axial bore 32 by a friction fit. The
positioning of the alignment member within the front
portion of the axial bore 32 may be further secured by
epoxy or ultrasonic welding. The alignment member 24
is generally cylindrical and has a cylindrical axial
cavity 38 with reduced diameter portion 40 providing
an opening adapted to accommodate the needle 14. The
reduced diameter portion 40 also provides an internal
annular surface 42, which functions as an abutment for
the forward end of a compression spring 44.
The rear or rearward end of the front alignment
member 24 abuts against a reduced diameter portion 34
of the axial opening through the forward end 25 of the
housing 12. A needle retaining member 36 is firmly
held in the reduced diameter portion 34 of bore 32, in
the forward end 25 of the housing 12. The forward end
of the needle retaining member 36 abuts against the
rearward end of the front alignment member 24. The
rear end of the needle retaining member 36 is provided
with latch means generally designated 45. The latch
means is preferably provided by a plurality of
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latching projections or crooked fingers designated 46
formed at the rear end of the needle retaining member.
The fingers 46 extend from the rear of the needle
retaining member 36 into an outwardly tapered portion
of the interior of the housing 12 at a junction 25a
between the enlarged diameter barrel portion 33 and
the reduced diameter front portion of the housing 12.
The barrel extends rearwardly for the remainder of the
length of the housing 12. The latching projections or
crooked fingers 46, more specifically have hooks 56
integrally formed at their ends, which extend radially
inward for retaining the needle 14 in position, as
further described hereinbelow. In the present
preferred embodiment four fingers are employed, as
shown in FIG. 3, but more or less latching projections
may be employed depending on the size of the device,
the nature of the spring 44 and other obvious
variables.
The interior of needle retaining member 36 is
hollow to accommodate the needle 14 and its
surrounding spring 44. It should be apparent that the
axial cavity or hollow area in the needle retaining
member is coextensive with the axial cavity or opening
in the front alignment member 24 to accommodate the
needle and its associated spring 44. The structure of
the needle includes the needle 14 and an increased
diameter head 50 attached thereto. The head 50 of the
needle functions as a cooperating latch member with
the latching projections or fingers 46. The needle
head 50 includes an enlarged portion having an annular
= forward surface 52 which provides an abutment 55 for
the rear end of spring 44 for compressing the spring
with abutment 42 on the front alignment member 24.
The needle head 50 includes another abutment surface
57, which is formed as a lip or rim that is maintained
in abutment with the hooks 56 or fingers 46. Hence,
the spring 44 is maintained in compression between the
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forward surface 52 of the needle head 50 and the
rearward interior surface 42 of the front alignment
member 24, to bias the needle toward the rear of the
device.
The cooperative relationships among the needle retaining member 36, needle
head 50, needle 14, and
the spring 44, are best shown in the exploded view of
FIG. 3. As previously discussed, the needle retaining
member 36 includes rearward extending fingers or
latching projections 46 having hooks 56 at the
terminal ends thereof. The fingers 46 are preferably
flexible to permit their outward movement to have the
latching projections release the cooperating latch
abutment 57 on the head 50 of the needle. It should
also be apparent that the fingers could be fractured
when moved outwardly to release the needle head. The
hooks 56 provide engaging surfaces 60 which extend
radially into the cavity 38 for engagement with the
abutment surface 57 of the needle head 50.
As should be appreciated, when the fingers 46 are
deformed or flexed radially outward, the engaging
surfaces 60 of hooks 56 would be moved out of abutment
with the abutment surface 57 of the needle head 50.
Upon this occurrence, The compressive force of spring
44 against the forward surface 53 of the needle head
50, would immediately thrust the needle head 50, and
hence the needle 14, rearward toward the rear of the
device. Referring again to FIG. 2A, an actuating
member 64 is slidably positioned within the barrel 33
of the housing 12 for effecting such disengagement of
the latching structure to free the needle head 50 for
having the needle fully retracted into the device.
The forward end 64a of the actuating member 64 is
contoured or wedge shaped to mate with cooperating
wedge shaped surfaces 58 of the hooks 56, for
spreading the fingers 46 to release the latching
structure. More specifically, the actuating member 64
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preferably has a tapered forward end 66 which engages
complementary sloping faces 58 of the hooks 56, when
the actuating member is urged forward within the
barrel 33 of the housing 12. The forward motion of
the actuating member 64 causes the fingers 46 to
spread radially outward by flexing or breaking, thus
releasing the head of the needle. When the head of
the needle is released, the needle is thrust rearward
by the spring and is propelled through an aperture 70
in the forward end of the actuating member 64.
An 0-ring 74 is held in an annular recess around
the actuating member to be in sliding engagement
between the actuating member and the interior of the
barrel 33. The 0-ring arrangement maintains the
aperture 70 in alignment with the needle head for
unhindered retraction of the needle. Alternatively,
the actuating member may be formed to fit within the
barrel and to maintain alignment therein by an
integral sliding seal.
An alternative embodiment of the needle retaining
member 36 is shown in FIG. 4, wherein members similar
to those in FIG. 3 are shown with the same number
designator with the addition of primes thereto. The
latching projections or fingers 46' and the hooks 56'
of the needle retaining member 36' are effectively
joined together to form an annular latching member
with a circular opening at the top or rear end. The
retaining member is provided with V-shaped
longitudinal grooves 47 running along the outside
toward the rear end to facilitate breakage of the
latching surface 58 by the activating member. The
engaging surfaces 60' of the hook surface 56' forms a
a continuous rim within the interior of the needle
retaining member 36', to enhance the security of
engagement with the needle head. The continuous rim
provides a seal with the rearward rim of the needle
head, so that fluid is kept out of the needle
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compartment. Additionally, a radially-protruding
shoulder 49 is formed around the exterior of the
needle retaining member 36' for abutment with a
complementary ridge on the interior of the stylet
housing (not shown) to secure the needle retaining
member against being pushed rearward by the expansive
force of the compressed spring. When the tapered end
of the actuating member 64 is urged against the
sloping face 58' of hook surface 56' with sufficient
force, the resulting outward radial force on the hook
surface 56' serves to break the latching end of the
retaining member along the grooves 47 to snap the
retaining or latching end of the retaining member.
More specifically, continued pressure on the actuating
member forces the latching member to deform radially
outward, by flexing outwardly into segments which are
separated along the grooves 47 or bybreaking the
separated segments of the latching end to release the
needle head.
Prior to, and during insertion of the stylet and
catheter into the patient, the actuating member 64 is
maintained at a fixed position, so that the needle is
not prematurely retracted. Preferably, the actuating
member 64 is maintained at a first or rearward
position within the barrel, so that the rear of the
actuating member protrudes from the rear of the barrel
33, as shown in FIGS. 1 and 2B. Additionally, it is
preferable for the actuating member to remain locked
within the barrel 33, at its second or forward
position, after the needle is retracted into the
device, in order to prevent access to a contaminated
or used needle. Both of these objectives are attained
by the dual-position locking mechanism provided at the
rear end of the device, as shown most clearly in the
enlarged view in FIG. 2B.
The rear ofthe housing 20 has an open end to
receive the actuating member 64 within the barrel 33
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during assembly of the device. The actuating member
64 has first locking tabs 76 thereon, which extend
outward from the exterior of the actuating member 64,
as in the form of a rim or tooth. The first locking
tabs 76 extend slightly beyond the internal diameter
of the barrel and have sloping forward surfaces
thereon, to allow the tabs 76 to be forced or press-
fitted into an internal circumferential groove 78
formed in the interior surface of the barrel. A lip
80 is formed in the interior of the barrel toward the
open end between groove 78 and the open end of the
barrel 33. Second locking tabs 84 are formed on the
exterior of the actuating member 64 around its
circumference, the second locking tabs 84 being
located to the rear of the first locking tabs 76.
When the actuating member is positioned within the-
barrel 33 during assembly of the stylet, the lip 80 is
caught between the rear surfaces of the first locking
tabs 76 and the forward surfaces of second locking
tabs 84. Hence, the actuating member is thereby held
at a first fixed position within the barrel 33 for
initial use of the device in insertion of the
catheter.
The forward surfaces 84a of the second locking
tabs 84 are angled or ramped to mate with
complementary angled rearward surfaces 80a of the lip
80. In activation of needle retraction, the actuating
member is pushed or urged forward within the barrel 33
with sufficient force to cause the second locking tabs
84 to enter the barrel 33 by virtue of a radial
deforming force exerted mutually between the angled
surfaces of the second locking tabs 84 and the lip 80.
Continued forward motion of the actuating member
within the barrel is eventually halted by abutment of
the rear end of the housing 12 with an enlarged
annular stop 86 forming the-rear head of the actuating
member 64. In other words, when the actuating member
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64 is urged forward into the barrel 33, the second
locking tabs snap into the groove 78, thus producing a
distinct audible and tactile sensation indicating that
needle retraction has been effected. Hence, the
doctor does not need to look at the stylet 12 in order
to ascertain whether the needle has been retractesd.
The force required to effect retraction is
sufficiently high to minimize undesirable premature
retraction, yet sufficiently low that the average
person can effect retraction with one hand. Referring
again to FIG. 1, retraction of the needle 14 is
preferably effected by pressing the enlarged head or
stop 86 of the actuating member 64 against the palm of
the hand. As previously mentioned, the forward end of
the stylet is gripped during use, between the thumb
and a forefinger of the dominant hand, with the rear
of the stylet aligned with the palm. In order to
effect retraction, the doctor merely flexes the
gripping thumb and finger firmly toward the palm while
maintaining a natural grip on the stylet. Hence, the
doctor does not need to be distracted from attending
to the inserted catheter in order to render the stylet
in a safe condition with the needle retracted and to
receive confirmation that the safety feature has been
activated. Alternatively, needle retraction can be
effected by any other techniqu.e for applying the
predetermined actuating pressure to the rearwardly
protruding head of the actuation member 64.
When the actuating member 64 has moved the
latching projections or finger to unlatch or release
the latch surface of the head of the needle, the
needle is freed for retraction. As the head of the
needle is freed, the spring forces or shoots the head
of the needle and attached needle into the barrel, and
particularly into the chamber 72 in the activating
member 64. Of course, the device is dimensioned to
permit the entire length of the needle to be received
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into the device so that no portion of the needle
protrudes from the front alignment member 24 after
retraction.
A vent plug 90 is positioned within the opening
of the rear end of actuating member 64 and is adapted
to seal the rear of chamber or compartment 72. The
vent plug is preferably formed of a resilient porous
material that allows air to escape from within the
compartment 72 during a blood return. The vent plug
90 is preferably adapted to become clogged when wet so
as to prevent any leakage of blood from the rear end
of the stylet. In alternative embodiments, the rear
end of the compartment 72 may be sealed with a solid
sealing member, as long as the compartment 72 is of
sufficiently large volume that blood return is not
significantly hindered by the back pressure produced
therein when the volume is reduced by the influx of
blood. The housing 12 and the actuating member 64 are
preferably transparent to permit the blood return to
be easily visible by the user.
It should be apparent to those skilled in the art
that further additions and modifications may be made
to the device as disclosed herein. Furthermore, terms
and expressions which have been employed are used as
terms of description and not of limitation. There is
no intention in the use of such terms and expressions
of excluding any equivalents of the features shown and
described or portions thereof. It is recognized,
however, that various modifications are possible
within the scope of the invention as claimed.
