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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to cannulas of the type used to perform laparoscopic
surgery and, more particularly, to structure for maintaining a cannula in
operative position with respect to body tissue through which the cannula
extends.
2. Background Art
In performing laparoscopic surgery, an incision is made in a patient to
admit a cannula which serves as a conduit for the introduction of selected
surgical instruments into a body cavity. During a surgical procedure,
several cannulas may be directed into the patient at spaced locations to
facilitate simultaneous use of a number of instruments. The body cavity in
which the operation is performed is filled with a gas to expand the
surrounding tissue to create a suitably sized operating space.
In designing laparoscopic equipment, there are several objectives. First,
it is important to confine the gas used to expand the cavity in which the
operation is to be performed with the cannula in operative position.
Deflation of the body cavity could result in interruption of a surgical
procedure and/or injury to the patient's internal organs.
It is also important that the cannula be positively maintained in its
operative position on the body tissue through which it passes. By
positively positioning the cannulas, internal and external clashing
between multiple instruments is minimized.
A further objective is to permit the cannula, in its operative position, to
to be reoriented with respect to a cavity to maximize the working range
for each instrument and thereby minimize the number of cannulas that must
be used.
Generally, the above three objectives are competing. For example, by
positively maintaining the cannula in its operative position, the leakage
of gas may be minimized, however the range of motion for the instrument
extending through the cannula may be limited.
Examples of prior art structures utilized to maintain a cannula in an
operating position with respect to tissue through which the cannula
extends are shown in each of U.S. Pat. Nos. 3,039,468, to Price;
3,253,594, to Matthews et al; 3,459,175, to Miller; and 4,077,412, to
Moossun. In each of the above four patents, a disk with a large surface
area is borne against one side of a tissue through which the cannula
extends to thereby positively maintain the position of the cannula. The
large contact area between the disks and tissue minimizes the amount of
permissible repositioning of the cannula with respect to the tissue.
Further, if the disk is brought sufficiently tightly against the tissue to
maintain the position of the cannula, the underlying tissue may be
traumatized.
There is another drawback with prior art structures utilizing an inflatable
balloon/membrane to maintain the cannula in operative position. With such
devices, a balloon is inflated to provide an obstruction to removal of the
cannula from an incision. A tube/conduit is required to selectively
inflate and deflate the balloon from a point externally of the body.
Exemplary prior art conduits are shown in U.S. Pat. Nos. 3,253,594, to
Matthews et al and 3,459,175, to Miller. In each, the exposed conduit is
separately passed through an incision in the body tissue. The opening for
the conduits affords another escape route for gas within the cavity. The
conduits are also prone to being severed or pinched. Further, the conduits
are difficult to clean and potentially unsanitary when reused.
The present invention is specifically directed to overcoming the
above-enumerated problems in a novel and simple manner.
SUMMARY OF THE INVENTION
According to the invention a laparoscopic cannula is provided having a
sleeve defining a hollow passageway through which a surgical instrument
can be directed and having a proximal end and a distal end which projects
into a cavity with the sleeve in its operative position, expandable
structure at the distal end of the sleeve which is selectively expandable
and collapsible and which prevents withdrawal of the sleeve in its
expanded state, structure for selectively expanding and collapsing the
expandable structure, a retaining collar with a tapered surface, and
cooperating structure on the sleeve and collar for permitting movement of
the collar relative to the sleeve towards the sleeve distal end whereby
body tissue through which the sleeve is directed can be captured between
the tapered collar surface and expandable structure to maintain the sleeve
in its operative position.
The tapered collar surface is caused to penetrate the body tissue and
thereby maintain a leakproof seal around the incision. The collar does not
have to be squeezed tightly against the body tissue to effect this seal
and thus the possibility of local traumatization is minimized.
In a preferred form of the collar, the tapered surface thereon defines a
truncated cone with the surface making an angle of preferably
approximately 15.degree. or greater with respect to the cone axis.
Further, the collar and expandable structure permit a significant amount of
reorientation of the cannula in its operative position without
compromising the integrity of the seal at the incision.
At the same time, the cannula is sufficiently positively maintained in its
operative position so as to minimize internal and external clashing of
instruments and facilitate placement in and removal of instruments from
the body cavity through the cannula passageway.
Preferably, the expandable structure is a flexible membrane which surrounds
the distal end of the sleeve. In a preferred form, the membrane is made
from polyethylene teraphthalate which is sufficiently durable to resist
rupture and positively prohibit withdrawal of the cannula from an
incision. The material is nonetheless sufficiently flexible to permit
significant reorientation of the cannula during an operation.
Another aspect of the invention is the provision of structure to block the
passage of gas through the cannula passageway at times when there is no
instrument in the cannula. In one exemplary embodiment, a hinged door is
provided on the cannula and is engaged and opened by an instrument
directed through the cannula passageway. Upon the instrument being
withdrawn, a spring urges the door back to its closed/sealing position.
Another aspect of the invention is the formation of the sleeve in at least
two parts. In a preferred form, one sleeve part defines at lest part of a
conduit that is used to direct air against the membrane/balloon to effect
inflation thereof and to exhaust air to collapse the membrane/balloon. The
one sleeve part can be made by extrusion and preferably of plastic or
fiberglass so as to be a low cost, disposable item. In a preferred form,
the one sleeve part is threadably mated with a second sleeve part having
the door to block the cannula passageway. The result is that the
relatively expensive second part of the cannula, generally made at least
in part from medical grade stainless steel, which remains externally of
the patient, can be reused, whereas that part of the cannula that
penetrates the patient can be disposed of and readily replaced.
The one sleeve part can be made in different lengths which can be selected
depending upon the particular type of surgery and patient.
In a preferred form, the collar is designed to be removably slid over the
first sleeve part and has a set screw to fix the position of the collar on
the sleeve. The collar can be separated from the disposable first sleeve
part and replaced on another like disposable sleeve part to cooperate with
the reusable sleeve part.
In a preferred form, each of the first and second sleeve parts defines a
part of the sleeve passageway.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a section view of a laparoscopic cannula according to the present
invention in operative position with respect to body tissue through which
the cannula extends;
FIG. 2 is an enlarged section view of a membrane/balloon on the cannula for
preventing withdrawal of the cannula from the tissue; and
FIG. 3 is a section view of a piece of tissue with several cannulas
according to the present invention extended through the tissue and each in
operative position.
DETAILED DESCRIPTION OF THE DRAWINGS
In FIG. 1, a preferred form of laparoscopic cannula, according to the
present invention, is shown at 10 in operative position with respect to
body tissue 12, as for example the abdominal wall of a patient, through
which the cannula 10 extends. The cannula 10 has a sleeve 14 with a
proximal end 16, which remains externally of a patient and through which
the cannula 10 is manipulated, and a distal end 18, which is directed into
a cavity 20 through the tissue 12. The sleeve 14 defines, a passageway 22
for communicating through the tissue 12 with the cavity 20.
To insert the sleeve 14 into the operative position of FIG. 1, a spike 24
is first directed through the sleeve passageway 22. An enlarged head 26 on
the spike 24 arrests movement of the spike 24 through the cannula
passageway 22 in a position wherein a sharpened end 28 of the spike 24 is
exposed at the distal end 18 of the sleeve 14.
An incision (not shown) is made in the tissue 12. The sleeve 14 with the
spike 24 therethrough is directed through the incision until the distal
end 18 of the sleeve 14 is exposed in the body cavity 20.
To maintain the sleeve 14 in its operative position, the present invention
contemplates the use of an inflatable membrane/balloon 30 at the distal
end 18 of the sleeve 14 and a cooperating collar 32, surrounding the
sleeve 14 and movable lengthwise relative thereto.
The details of the membrane are shown in FIG. 2. The membrane 30, which is
preferably made from polyethylene teraphthalate, surrounds the distal end
18 of the sleeve 14 and resides within an annular recess 34 defined in the
sleeve 14. In a collapsed state, as shown in phantom in FIG. 2, the
membrane 30 has a compact profile and projects radially outwardly
preferably not significantly further than the outer surface 36 of the
sleeve 16. The compact storage of the membrane 30 permits the sleeve
distal end 18 to be directed through the incision in the tissue 12 with
minimal interference.
Once the membrane 30 is fully within the cavity 20, it can be inflated as
through a syringe at 38 or through any other means, shown schematically in
FIG. 1 at 39. The syringe 38 directs pressurized air or fluid radially
outwardly of the sleeve 14 against the membrane surface 40. The membrane
30 is expanded sufficiently, as shown in FIGS. 1 and 2, that it prevents
the sleeve 14 from being withdrawn from the tissue 12. An exemplary
diameter of the expanded membrane 30 is 2.0 cm or greater, depending upon
the diameter of the sleeve 14. An exemplary dimension of the expanded
membrane 30 lengthwise of the sleeve 14 is 1-2 cm, again depending upon
the sleeve and incision size. It is preferred to make the membrane 30 at
least three times the size of the incision through which the sleeve 14
extends.
By exhausting air from the membrane chamber 42, the membrane 40 can be
collapsed to facilitate withdrawal of the sleeve 14 through the incision.
The details of the inflating/deflating mechanism at 44 will be described
below.
The collar 32 has a tapered surface 46 which, with the membrane 30
inflated, is urged towards the membrane 30, thereby compressing the tissue
12 and capturing the tissue 12 in conjunction with the membrane 30. The
collar surface 46 is shaped as a truncated cone. As seen in FIG. 1, a
substantial area of tapered surface 46 is brought into contact with the
tissue, thereby effecting a positive seal between the collar 32 and tissue
12.
The incline of the surface 46 is chosen so as to maximize contact area with
the tissue without causing penetration thereof sufficient to contact and
possibly rupture the membrane 30. In a preferred form of the invention,
the angle .alpha. that the surface 46 makes with the axis of the cone is
on the order of 15.degree. or more. However, the angle may vary depending
upon the thickness and nature of the tissue.
By reason of the substantial contact area between the surface 46 and tissue
12, it is possible to reorient the length of the sleeve 14 so that, for
example, it is along the center lines 50, 52, without leakage, of gas from
the cavity 20. If the sleeve 14 is tipped, so that it aligns with center
line 50, the left side 54 of surface 46 tends to pull away from the
tissue, yet not sufficiently that it disengages therefrom. Consequently,
the seal remains intact entirely around the incision. The membrane 30 is
sufficiently flexible to likewise conform to the inside surface 56 of the
tissue 12 upon reorientation of the sleeve 14 and is sufficiently durable
that it will not be prone to rupture when so deformed.
Because of the tapered configuration of the surface 46, a substantial
amount of penetration can occur without traumatizing the tissue 12 around
the incision. Once the collar 32 is appropriately positioned, a set screw
58 on the collar 32 can be tightened against the outer surface 36 of the
sleeve 14. The sleeve 14 is thus positively maintained in the operative
position of FIG. 1.
Another aspect of the invention is the provision of a door 60 to seal the
passageway 22 in the absence of an instrument (not shown) or spike 24
being extended into the passageway 22. The door 60 is hingedly connected
at 62 for pivoting movement relative to a radially enlarged flange 64 at
the proximal end 16 of the sleeve 14. In the closed door position, a
rounded projection 64 seats sealingly against a rim 66 on the flange 64.
The closed door is intercepted by an instrument or the spike 24 being
directed downwardly through the passageway 22 so that the door 60 is
thereby pivoted to the open position in FIG. 1. Upon the instrument being
removed, a spring 68 associated with the door 60 urges the door 60 back to
its closed position. The door mechanism resides within a cavity 70 defined
by a housing 72.
The cannula sleeve 14 is preferably defined in two parts. A first part 74
defines the passageway sealing structure including the door 60. The first
sleeve part 74 remains externally of the patient at all times and is
fabricated preferably mostly from medical grade stainless steel.
The second sleeve part 76 is directed through the tissue 12 and defines a
conduit 78 through which the membrane 30 is selectively inflated and
deflated. In a preferred form, the second sleeve part 76 is formed of
plastic by extrusion. Fabrication from any other rigid material, such as
fiberglass is also contemplated. The conduit 78 extending lengthwise of
the sleeve part 76 can be formed in the extrusion process. The sleeve part
76 can be readily and economically manufactured so as to be disposable. It
is thus possible to reuse the first part 74 and provide individually
sterilized second parts 76, which are threadably connected at 80 to the
first part 74. Other connections between the parts 74, 76 are also
contemplated, such as bayonet, friction fit, etc.
The parts 76 can be made in a variety of lengths to be suitable for
different types of operations and for different patients. By minimizing
the amount of projection of the part 76 into the cavity 20, the range of
movement of the instruments in the cavity 20 is maximized.
The distal end of the second sleeve part 76 is undercut, as through the use
of heat, to define the recess 34 and has a plurality of radially extending
outlet ports 82 in communication with the conduit 78. Inflation and
deflation of the membrane 30 is accomplished through the ports 82. The
conduit 78 communicates through a chamber 84 on the sleeve part 74 with a
conduit 86 integrally formed with the sleeve housing 72. The conduit 86
has a shut-off and/or one-way valve 88, which can be operated to prevent
escape of air or fluid from the membrane chamber 42 with the membrane 40
inflated.
To place the cannula 10 in its operative position, the membrane 30 is
deflated to the phantom position in FIG. 2. The spike 24 is directed
through the cannula passageway 22 so that the spike end 28 projects from
the distal end 18 of the sleeve 14. The spike 28 and surrounding sleeve
are then directed through an incision in the tissue 12 until the recess 34
is entirely within the cavity 20. A valve 88 is opened and the syringe 38
or other pressurized air source is operated to inflate the membrane 30.
Once the membrane 30 is fully inflated, the shut-off valve 88 can be
closed to confine the air or fluid in the membrane 30. The spike 24 can
then be removed from the sleeve 24 whereupon the door 60 closes to seal
the passageway 22. The collar 32 is then urged towards the membrane 30,
thereby compressibly capturing the tissue 12 in conjunction with the
membrane 30. The set screw 58 is tightened to fix the location of the
collar 32 and thereby maintain the cannula 10 in its operative position so
that a desired instrument can be directed through the passageway 22 into
the cavity 20.
To prevent escape of gas from the cavity 20 between the collar 32 and
sleeve 14, a gasket 90 is provided on the end of the collar 32. A similar
gasket 92 is provided at the proximal end 16 of the sleeve to sealingly
cooperate with an instrument extended through the passageway 22.
FIG. 3 shows an arrangement of several of the cannulas 10 which may be
simultaneously utilized during an operation. Relative orientations of the
cannula 10 are fixed sufficiently that internal and external clashing
between the cannulas 10 and any instruments extended through the sleeve 14
thereon is minimized.
The foregoing disclosure of specific embodiments is intended to be
illustrative of the broad concepts comprehended by the invention.
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