Note: Descriptions are shown in the official language in which they were submitted.
TROCAR ASSEMBLY
Description
Technical Field
The invention is in the field of surgical
instruments. More particularly it concerns a novel
trocar.
Background Art
Trocars are sharp pointed surgical instruments
used to puncture a body cavity. This is often done so
that fluids may be drained using a cannula inserted into
the opening. Trocars are also used dujring endoscopic
procedures. A conventional endoscopic procedure follows
three steps. The first step is the insertion of a Veress
cannula into the abdominal cavity through a small
incision in the abdominal wall. The Veress cannula
includes a hollow needle having a sharp point with an
inside diameter of approximately 0.5 mm. When the cavity
is entered, a spring-loaded pin inside the lumen of the
n~edle pops out to extend a short distance, typically 1
mm, beyond the needle1s point. This protects against
inadvertent laceration of intra-abdominal structures.
Because the pin is spring-loaded, it is not able to
protrude beyond the needle's point until the abdominal
cavity is entered. Next, the abdominal cavity is
inElated with a gas through a small lumen in the Veress
cannula. After inflation, the Veress cannula is removed.
Finally, a standard trocar housed within the bore of a
trocar tube is thrust into the inflated abdomen.
Standard trocars are shaped like a large metal pey with a
sharpened point, having a diameter varying Erom 3-12 mm.
The trocar is then removed and the endoscopic instrument
~5~i3~
is inserted into the abdominal cavity through the trocar
tube.
One problem with the prior art method is that
the sharpened tip of the trocar, after being thrust
through the abdominal wall, can inadvertently puncture or
lacerate intra-abdominal tissue. Also, conventional
trocars are generally made from hardened steel with
sharpened e~ges. These trocars must be sterilized
between uses, which is o~ten inconvenient. Also, the
hardened steel blades must be sharpened to assure proper
cutting action.
Disclosure of the Invention
The present invention relates to a trocar
assembly that is lightweight, easy to use, disposable if
desired, and much safer to use than previous trocars.
The trocar assembly of the invention comprises
an elongate trocar obturator having a piercing tip at its
front end and an elongate trocar tube in which the trocar
obturator is housed characterized in that the trocar
assembly includes a tubular protective shield mounted
concentrically around the trocar obturator and being
axially movable relative to the trocajr obturator between
a normally extended position and a retracted position and
a spring acting on the rear end of the protective shield,
whereby the shield is forced to said retracted position
to expose the piercing tip when the trocar is being
inserted through the wall of a body cavity and is biased
by the spring to said extended position to shield the
piercing tip once the trocar has pierced the wall.
Brief Description of the Drawings
Figure 1 is an isometric view of one embodiment
of the trocar assembly of the present invention.
--3--
Figure 2 is a cross-sectional view of the
trocar and trocar tube of Figure 1.
Figure 3 is an enlarged, exploded view of the
trocar of Figure 2.
Figure 4 is a Eront end view of the trocar
assembly o:E Figure 1.
Figures 5A and 5B are isometric views of the
trocar of Figure 2 with the shield in extended and
retracted positions.
Figure 6 is an isometric view of an
alternative, preferred embodiment of the trocar assembly
of the invention.
Figure 7 is a sectional plan view of the trocar
of Figure 6 taken along line 7-7.
lS Figure 8 is a sectional vie~ of the trocar of
Figure 6 taken along line 8-8.
Figure 9 is a partial sectional view of the
trocar of Figure 6 taken along line 9-9.
Figure 10 is an exploded vie~ of the trocar o~
Figure 6.
Fiyure 11 is an end view of the piercing tip of
the trocar of Figure 6.
i~ode~ ylng Out the Invention
__ _
Fiyures 1 through 5 depict a trocar assembly,
generally designated 2, that includes a trocar 4 and a
trocar tube 6.
Trocar 4, shown best in Figures 2 and 3,
includes an elongate tubular body 8 having a central axis
10 and open front and reae ends 12, 14. A piercing tip
16 is mounted to Eront end 12 of body 8 by an elongate
shaft 18 extending along central axis 10 between tip 16
and end cap 20.
3~7
--4--
Piercing tip 16 includes three blades 22
extending from a central portion 24 between a common
point 23 an~ a shoulder 25. Each blade 22 has a cutting
edge 21 extending between common tip 23 and an outer end
19. Portion 24 includes a rearwardly extending peg 26
si~ed to fit within a bore 28 within,one end of shaft 18.
Pey 28 is fixed within bore 28 and the other end of shaft
18 is fixed within a bore 27 in cap 20 using a suitable
aahesive. Shaft 18 is sized so the outer ends 19 of
cutting edges 21 are generally aligned with leading
surfaces 29 at Eront end 12 of body 8. Tip 16 does not
move relative to body 8.
Piercing tip 16 may be stainless steel or of
some other suitable material. If trocar 4 is to be a
single use, disposable instrument, piercing tip 16 may be
made Erom metal, hard plastic or some other material
suitable for single use applications.
Housed within body 8 and surrounding tip 16 is
a protective shield 30. Shield 30 is a yenerally
cylindrical tubular member having a central bore 32 with
an enlarged region 34 at the rear end 36 of shield 30.
Shield 30 includes a cylindrical outer surface 37 sized
for sliding movement alony central axis 10 within body 8
and a Eorward and inwardly tapering conical outer surface
2~ 38. Three radially extending slots 40 are formed through
protective shield 30 and extend from the front~end 42 of
shield 30 to a position medially alony the protective
shield. Slots 40 define three Eingers 41 so that blades
22 are housed within slots 40 and between fingers 41;
central portion 24 is housed within central bore 32. To
mount shield 30 over tip 16, fingers 41 are separated at
front end 42 and peg 26 and central portion 24 are
inserted past Eront end 42 and into bore 32.
A spring 44 is captured between end cap 20 and
enlarged region 34 to bias shield 30 forward in the
direction of arrow 46 towards front end 12 oE tubular
body 8 so that fingers 41 normally cover or shield blades
22 of piercing tip 16. This position is shown in Figures
1, 2 and 5A. Such forward movement is halted when the
bases 47 of slots 40 engage shoulders 25 of blades 22.
During use, as described below, protective shield 30 is
pushed rearwardly away from point 23 of tip 16 thus
exposin~ tip 16 as shown in Figure 5B.
Trocar tube 6, shown in Figures 1 and 2, is
used in a conventional manner to guide trocar 4 in
piercing the abdominal wall of the patient and also Eor
later guiding a medical instrument, such as an endoscopic
instrument (for exploration of the b~dy cavity) or a
cannula (for draining fluids from the body cavity).
Trocar tube 6 inclues a generally tubular body 48
deEining a central bore 50. A pair of gripping lugs 51
extend from body 48. Bore 50 is sized for axial sliding
movement of trocar 4 therein.
Bore 50 includes an enlarged rear region 52
which houses a somewhat spongy cylindrical seal 54O Seal
54 is captured between a shoulder 56 in body 48 and a
washer 58. ~asher 58 is pressed against seal 54 by a
cylindrical threaded sleeve 60 threadably mounted to the
rear end 62 of body 48. As shown in Figure 2, the inside
diameter of seal 54 is norsnally about the same as that of
the main portion 63 of central bore 50. Tightening
threaded sleeve 60 against washer 58 compresses
cylindrical seal 54 axially to deform the seal radially
inwardly against the outer surEace of the trocar 4 or
other device housed therein.
Body 48 includes a valve 64 fluidly
communicating with main region 63 oE central bore 50.
Cylindrical seal 54 insures that when a pressurized gas
is pumped into central bore 50 through valve 64, or when
a partial vacuum drawn on central bore 50 through valve
64, seal 54 blocks the potential flow path through region
52.
In use, trocar 4 is inserted into trocar tube
6. Ilowever, threaded cap 60 is not tiyhtened down to
allow trocar 4 to slide easily within trocar tube 6.
After the patient's abdomen has been properly inflated
with a gas, as described in the Background Art section,
trocar 4, guided by tube 6, is used to pierce the
patient's abdominal wall. Because of the substantial
resistance of the abdominal wall, protective shield 30 is
pushed rearwardly to allow piercing tip 16 to pierce and
pass through the abdominal wall. Once piercing tip 16
has passed through the abdominal wall and enters the
abdominal cavity, spring 44 biases protective shield 30
forward in the direction of arrow 46 to cover blades 22;
this helps protect against any inadvertent puncturing or
laceration oE intra-abdominal tissues. If desired trocar
4 can be partially withdrawn from tube 6, sleeve 60
tightened and a gas introduced into the patient's
abdominal cavity through valve 64. Seal 54 both secures
trocar 4 in place and prevents gas from leaking past it.
During, for example, an endoscopic examination,
trocar 4 is withdrawn Erom tube 6 and an endoscopic
instrument (not shown) is inserted into the abdominal
cavity of the patient through trocar tube 6. To keep the
abdomen inflated, a gas can be slowly Eorced into the
abdomen through valve 64. The gas passes along central
bore 50 between tubular body 48 and the endoscopic
instrument and finally into the abdominal cavity through
holes 68 formed within tube 48 at Eront end 66 of tube 6.
To keep the gas from escaping past region 52, threaded
--7--
ca~ 60 is tightened onto washer 58 to squeeze cylindrical
seal 54 between the interior wall of tubular body 48
bounding region 52 and the outside surface of the
endoscopic instrument. ThiS also helps to keep the
medical instrument in place.
Figures 6 through 11 depict an alternate trocar
assembly, generally designated 70, composed of a trocar
subassembly 72 and a trocar tube subassembly 74.
The two subassemblies are interfitting, but designed to
be separable from each other. Referring to Figures 7 and
10, the basic elements of trocar subassembly 72 are a
head or grip 76 composed of identical halves 78, 80
that are held together by fastening means such as snaps,
adhesive, welds, or screws (not shown); an obturator 82
having a piercing tip 84; a tubular obturator sleeve or
snield 86, and a spring 88 for biasing the shield. Grip
76 has a concave front wall 90 a central cylindrical bore
92 that extends from the wall 90 partly through the grip.
The cylindrical wall of bore 92 carries a pair of mating,
diametrically opposed posts 94 (one in each grip half)
that are received through axial slots 96 and 98 in the
shield 86 and obturator 82, respectively, for lockiny the
obturator and shield in the subassembly. The end wall
100 of bore 92 has a generally cubic slot 102 that
receives a cubic key or pin 104 on the rear end of
obturator 82 for preventing rotation of the obturator.
Helical spring 88 fits around the rear end of the
obturator with its ends seated against wall 100 and the
rear end wall of tubular shield 86. As described in
detail below the spring biases the sheath forwardly to an
extended position. In this regard slot 96 in the shield
is elongated axially to permit limited axial movement of
the shield relative to the obturator.
I
The piercing tip 84 has a pointed head 106 that
serves to pierce through the wall of the body cavity and
a cylindrical shank 108 that fits into a bore 110 in the
front end of the obturator. The shank may be fixed in
the bore or be mounted removably therein by means of
threads or set screws. Removable mounting allows the
tip to be removed for sharpening or cleaning or be
replaced, if desired. The pointed end of the head is
defined by three flat surfaces (Figure 11) that Eorm a
pyramid. Alternatively the head may be conical in shape.
The principal elements oE trocar tube
subassembly 74 are: a head or grip 112 composed of two
identical halves 114, 115 that are held together by
fastening means (not shown); a trocar tube 116 and a
slide valve assembly, generally designated 118. The rear
wall of grip 112 has a convex shape that mates with the
concavity of the front wall of the grip of the trocar
subassembly so that the two subassemblies fit together
snugly (Fiyures 6 and 7). As shown in Figure 10, the
grip has a central cylindrical bore 120 that extends
through the grip from its front wall to its end wall. It
is composed of a front section 122 that receives the
trocar tube 116 and a rear section 124 that receives the
obturator/shield of the trocar subassembly. It is
traversed by a cylindrical cavity 126 that is adapted to
receive body 123 of the slide valve. Front section 122
has a circumferential slot 130 in it that receives a
circumferential collar or flange 132 formed on the rear
end of trocar tube 116, whereby the axial position of the
tube in section 122 is fixed.
The body of the slide valve has a central
diametrical bore 134 that is adapted to receive the
obturator/shield of the trocar subassembly. The bore has
a radial locking tooth 136 that is adapted to engage a
_9~ 3~-~
valve locking slot 138 in the side of the trocar shield
~G during operation of the trocar. The top and bottom
(as shown in the Fiyures) of the cylindrical exterior of
the body carries pairs of spaced, axially aligned guide
posts 140 that fit, respectively, in axial slots 142
formed in the bottoms of the semicylindrical recesses in
the grip halves that define cavity 126 to prevent
rotation of the valve body. One end oE the valve body
carries a cylindrical shaft 144 that is received through
an opening 146 in one sidewall of the grip. The shaft
serves to support the body and as a point of manual
contact for sliding the valve axially within cavity 126.
The other end of the valve body has a cylindrical
extension 148 that serves in combination with stop 150 to
limit the axial movement of the valve in the cavity.
Stop 150 has a cylindrical body 152 ~hat aligns axially
with extension 148 and a head define,d by a pair of
axially spaced circumferential collars 154 one of which
abuts one end wall of the cavity 126 and the other of
which abuts the exterior surface of the grip end wall. A
coil spring 156 is received around extension 148 and stop
body 152 with its ends seated, respectively, against the
inner surface of the inner stop collar 154 and one end of
the valve body. Spring 156 serves to bias the valve body
axially.
The trocar of Figures 6-11 operates and is used
as follows. Before use the trocar will be in the
assembled form shown in Figures 6 and 7 with the two
subassembly grips fitting snuyly together and the trocar
obturator and shield inserted through bore 120 in the
trocar tube grip, bore 134 through the valve body, and
the lumen of the trocar tube. The trocar shield is
normally in a locked, extended forward position (shown in
phantom in Fiyure 7) due to the force exerted by spring
--10--
88 with locking tooth 136 of the valve engaged in the
locking slot in the trocar shield. In this position the
piercing tip is shielded from damaye or contamination.
The trocar assembly is held by means of the
interEitting grips of the two subassemblies and the
shieLded, leading end oE trocar is placed against the
skin that defines the outer surface of the wall of the
cavity to be pierced. The slide valve 118 is then
depressed (to the position shown in phantom in Figure 8)
by pressing on the exposed end of shaft 144. This action
moves the valve body toward the valve stop and disengages
tooth 136 Erom its locking slot, thereby permitting axial
movement of the shield. Exertion of pressure against the
skin with the trocar causes the shield to be pushed
rearwardly against the spring to a retracted position
(shown on solid line in Fiyure 7) to expose the piercing
tip of the trocar. The tip penetrates the skin and
underlying tissue with continued pressure. Pressure on
the end of shaft 144 is released shortly after the tip
begins penetrating the wall (i.e., after the locking slot
has moved rearwardly of the locking tooth position~.
Once the tip has penetrated through the wall and has
entered the cavity the force against the front end of the
shield ceases and the shield is automatically moved
axially back to its extended, locked position through the
action of spring 88. Viscera and other internal tissues
are thus protected from contact with the sharp piercing
tip and potential damage therefrom.
Once the cavity wall has been penetrated
completely by the leading end of the trocar subassembly
the slide valve can be re-depressed to disengage the
locking tooth and the obturator/shield removed from the
trocar tube by separating the trocar subassembly from
the trocar tube subassembly. This separation leaves an
3~
open channel defined by the bores 120 and 134 and the
lumen of the trocar tube to the body cavity through which
surgical instruments may be placed to view internal
tissues, per~orm operations thereon, or drain body
fluids. The slide valve 118 may, if desired, be designed
to move axially to a position in which its bore does not
align with section 122 to block the channel when the
trocar subassembly is withdrawn.
The trocar subassembly may, if necessary or
desirable, be equipped with sealing means similar to that
shown in the trocar of Figures 1-5 or seals
conventionally used in medical instruments. The slide
valve assembly may also be equipped with seals if
necessary or desirable.
Modifications of the above described modes of
carrying out the invention that are obvious to those of
skill in mechanical engineering, surgical instrument
design, or related fields are intended to be within the
scope of the following claims.
