U.S. patent application number 15/621336 was filed with the patent office on 2017-09-28 for trocar assemblies.
The applicant listed for this patent is Brandon Lee Michal, Nathanial Tran, Steven Williams. Invention is credited to Brandon Lee Michal, Nathanial Tran, Steven Williams.
Application Number | 20170274154 15/621336 |
Document ID | / |
Family ID | 51654952 |
Filed Date | 2017-09-28 |
United States Patent
Application |
20170274154 |
Kind Code |
A1 |
Williams; Steven ; et
al. |
September 28, 2017 |
TROCAR ASSEMBLIES
Abstract
A trocar assembly wherein a trocar with an elongated polygonal
tube can receive either an obturator or a medical instrument of a
dissimilar cross-sectional shape with the medical instrument of the
different cross sectional shape maintable in a central condition
therein to inhibit pressure losses to lateral flow to thereby
permit use of a cannula having a smaller cross sectional area than
a cylindrical cannula as well as inhibit trauma to an entry site
around the cannula.
Inventors: |
Williams; Steven; (Saint
Paul, MN) ; Michal; Brandon Lee; (White Bear Lake,
MN) ; Tran; Nathanial; (Lakeville, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Williams; Steven
Michal; Brandon Lee
Tran; Nathanial |
Saint Paul
White Bear Lake
Lakeville |
MN
MN
MN |
US
US
US |
|
|
Family ID: |
51654952 |
Appl. No.: |
15/621336 |
Filed: |
June 13, 2017 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13986120 |
Apr 3, 2013 |
|
|
|
15621336 |
|
|
|
|
61687231 |
Apr 20, 2012 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M 5/329 20130101;
A61B 17/3421 20130101; A61B 17/3474 20130101; A61M 5/3297
20130101 |
International
Class: |
A61M 5/32 20060101
A61M005/32; A61B 17/34 20060101 A61B017/34 |
Claims
1-11. (canceled)
12. A trocar comprising: a housing; a cannula having a polygonal
cross sectional shape for axially receiving either an obturator or
a cylindrical surgical instrument.
13. The trocar of claim 12 wherein the cannula comprises a
transparent material with a surface finish thereon normally
rendering the cannula opaque until moisture wets the surface
finish.
14. The trocar of claim 12 wherein a minimum diameter of the
cannula is greater than a maximum dimension of the surgical
instrument so that placement of the surgical instrument within the
cannula provides a set of triangular shaped peripheral fluid
passages therepast and a set of web faces for centering the
surgical instrument therein to inhibit failure of a trocar
seal.
15. The method of introducing a medical gas into a body cavity
during a medical procedure while minimizing trauma comprising the
steps of: forming an opening into a body cavity by inserting a
trocar assembly comprising a trocar having a cannula with a
polygonal shaped exterior surface through the body tissue of a
patient by pushing an end of the cannula through the body tissue
while allowing the body tissue to flow around an exterior surface
of the polygonal shaped cannula; removing an obturator from the
cannula; and inserting a surgical instrument into a polygonal lumen
in the polygonal shaped cannula wherein the surgical instrument has
a radial dimension from a center of the surgical instrument less
than a radial dimension from the geometric center of the lumen to a
web and the radial distance from the geometric center to an
internal corner of the polygonal cannula is greater than the radial
distance from the geometric center of the lumen to the web to
thereby provide a set of peripheral fluid passages between the
exterior surface surgical instrument and the interior surface of
the polygonal shaped lumen.
16. The method of claim 15 including the step of placing the
obturator in engagement with the webs of the polygonal tube to
enable rotation of both the cannula and the obturator during the
insertion of an end of the cannula into a body cavity of a
patient.
17. The method of claim 16 including the step of removing the
obturator and inserting a surgical instrument into the polygonal
lumen in the cannula.
18. The method of claim 17 including the step of maintaining a
surgical instrument in a central location within the polygonal
shaped lumen through engagement with the internal webs of the
polygonal tube.
19. The method of claim 17 including directing an insufflation gas
through the fluid passages between an interior surface of the
polygonal tube and an exterior surface of the surgical
instrument.
20. The method of claim 19 including the step of expanding the step
of unevenly expanding tissue around a port into the body cavity
with the polygonal cannula to reduce trauma to a patient.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to provisional application
Ser. No. 61/687,231 filed Apr. 20, 2012
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] None
REFERENCE TO A MICROFICHE APPENDIX
[0003] None
BACKGROUND OF THE INVENTION
[0004] Medical gasses are used to distend, or insufflate, a body
cavity in order to produce a suitable void in the body cavity,
which enables a surgeon to perform a minimally invasive surgical
procedure on a patient. For example, in laparoscopic surgery or
other types of invasive medical procedures one of the surgical
goals is to minimize trauma to the tissue surrounding the entry
port into the body cavity though the use of a cannula. Typically,
during laparoscopic surgery, a surgeon manipulates an instrument
inside of the patient through the cannula, which extends through
the body tissue and into the body cavity of a patient. Carbon
dioxide, which is the most prevalent insufflation gas used in
laparoscopic surgery, is also present in the cannula since it flows
into the patient's body cavity through the cannula while an
insufflator regulates the rate of delivery of the carbon dioxide
insufflation gas. Typically, the insufflator, which receives its
medical insufflation gas from a medical grade canister, transports
the medical insufflation gas to the cannula via a fluid conduit. An
oversized cylindrical cannula provides an annular gas flow passage
between the interior surface of the cannula, which usually has a
cylindrical shape, and the exterior surface of the medical
instrument, which also usually has a cylindrical shape.
[0005] In order to reduce the trauma to a patient one may want to
reduce the diameter of the oversized cannula, which surrounds the
medical instrument. Unfortunately, the reduction of the diameter of
the oversized cannula, which is beneficial since it reduces trauma
around the tissue pierced by the cannula, causes other problems
since the medical devices and surgical instruments introduced into
a lumen in the cannula increase the obstruction to the flow of the
insufflation gas that enters the body cavity through the same lumen
in the cannula. If a small surgical instrument is placed within a
cannula of reduced diameter the flow obstruction may not be
significant, however, with the use of larger and more complex
surgical instruments in a cannula, which is no longer oversized,
the pressure losses or pressure drop created by the annular like
passage located between the interior surface of the cannula and the
exterior surface of the medical instrument may have adverse
consequences if one wants to maintain the body cavity in an
inflated condition as well as the medical instrument in a sealed
relationship to the cannula.
SUMMARY OF THE INVENTION
[0006] A trocar assembly having an elongated polygonal cannula for
holding either an obturator or a medical instrument therein in a
slidingly interdisposed condition. The medical instrument is
slidably and rotationally interfitted within the cannula while the
obturator is slidably but rotationally engageable with the cannula.
The elongated cannula has an external shape allowing plastic flow
of body tissue there around to minimize trauma to a wound site
surrounding the cannula. With a medical instrument located in the
elongated polygonal cannula the exterior radial surface of the
medical instrument and the interior surface of the cannula, which
are of dissimilar cross sectional shape, coact to define a set of
peripheral fluid passages therebetween for introducing an
insufflation gas into a distended body cavity so that one can
maintain the body cavity in a distended condition during the a
medical procedure within the body cavity. The use of dissimilar
shapes of the cannula and the medical instrument enables the
internal surfaces of the cannula to form a centering guide to
maintain the medical instrument in a central position to lessen the
chances of disturbing the seal between the trocar and the medical
instrument as well as minimizing pressure losses. The use of
dissimilar shapes of the cannula also allows one to reduce the
trauma to the body tissue surrounding a cannula entry port into a
body cavity by allowing use of a smaller cannula. The cannula may
be made from a transparent material with a surface coating or
surface finish on the interior that normally renders the cannula
opaque but in response to moisture in the insufflation gas
increases the transparency of the cannula to provide a visual
monitoring of the presence of insufflation gas flow through the
cannula.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a perspective view of a trocar with the cannula
comprising an elongated polygonal instrument tube;
[0008] FIG. 2 is a perspective view of an obturator;
[0009] FIG. 2A is a perspective view of a trocar assembly with the
obturator located within the cannula;
[0010] FIG. 2B is a perspective view of a trocar assembly with a
medical instrument located within the cannula;
[0011] FIG. 3 is a cross sectional view of the polygonal cannula of
FIG. 1;
[0012] FIG. 4 is a cross sectional view of the obturator shown in
FIG. 2;
[0013] FIG. 4A is a cross sectional view taken along lines 4A-4A of
FIG. 2 of an obturator having a polygonal shape located in a
polygonal cannula;
[0014] FIG. 5 shows a cannula with a medical instrument extending
into the body of a patient;
[0015] FIG. 6 is a cross sectional view showing the interrelation
of a set of elongated peripheral fluid passages located between the
medical instrument and the interior of the polygonal cannula;
and
[0016] FIG. 7 is a sectional view of the trocar assembly taken
along lines 7-7 of FIG. 5 showing deformed body tissue surrounding
the exterior of the elongated polygonal cannula.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0017] FIG. 1 is a perspective view of a trocar 10 with a cannula
comprising an elongated polygonal instrument tube 13 connected to
housing 11, which includes a stopcock 12 for controlling ingress of
insufflation gas into the trocar 10. The cannula may be made from a
variety of rigid materials including opaque materials or
transparent materials, which contains a surface coating or surface
finish on the interior surface of the cannula that normally renders
the cannula opaque but in response to moisture in the insufflation
gas increases the transparency of the cannula through wetting of
the surface coating.
[0018] FIG. 2 is a perspective view of an obturator 15 comprising
an elongated shaft 17 having a conical tip 18 for piercing through
body tissue to enable insertion of the distal end of the cannula 13
into a body cavity to enable a surgeon to perform a medical
procedure through external manipulation of a medical instrument
extending through a working channel or lumen in the cannula 13.
[0019] FIG. 2A shows a trocar assembly 20 comprising the trocar 10
of FIG. 1 and the obturator 15 of FIG. 2 in an assembled condition.
The drawing shows the conical body piercing tip 18 projecting
axially outward beyond the distal end of the cannula 13 and the
head 16, which may have a higher coefficient of friction to provide
an enhanced grip. The tip 18, which extends out the opposite end of
the trocar may have a low friction surface coating thereon to
optimize the ability to permit a surgeon to force the tip 18
through the body tissue. Once the cannula 13 is inserted into the
patient the obturator 15 is removed and is replaced by a medical
instrument that can be manipulated by a surgeon from a position
external to a body cavity.
[0020] FIG. 2B shows a trocar assembly 19 comprising the trocar 10
of FIG. 1 together with an example of a typical surgical instrument
33. Surgical instrument 33 includes an elongated cylindrical shaft
36 for extending through cannula and handles 34 and 35 for use in
manipulation of the jaw 36 and jaw 37, which are located on the
distal end of the surgical instrument 33.
[0021] FIG. 5 shows an example of use of trocar assembly 19, which
comprises a cannula 13 and a medical instrument 33 having handles
35,34 located outside the body cavity of a patient 39 supported by
an operating table 38. As used herein the term trocar assembly may
refer to the trocar cannula 13 with either an obturator 15 located
therein or a medical instrument 33 located therein where the
medical instrument is used for performing a surgical procedure
within a body cavity with controls for the medical instrument
located external to the body cavity. In this example a tube 40,
which is connected to a source of insufflation gas, supplies the
insufflation gas to the patient 39 through the trocar cannula 13
which also contains the medical instrument therein.
[0022] FIG. 3 is a cross sectional view of the cannula 13, which
comprises an elongated polygonal tube 13, that extends outward from
the housing 11. In the example shown in FIG. 3 the elongated
polygonal tube 13 has the cross sectional shape of a regular cyclic
hexagon which is both an equiangular and equilateral polygon having
equal corner angles .THETA., sides or webs 13a-f of the same length
L.sub.1, as well as having all the corners located on a single
reference circle 9. A working channel 20 or lumen extends
longitudinal through the polygonal tube 13. For reference the
distances from a geometric center of the tube 13 to a web, which
forms a side of the polygon, is designated by R.sub.1 and the
distance from the geometric center of the tube 13 to the junction
of adjacent webs is designated by R.sub.2 with the dimension
R.sub.2 being greater than R.sub.1.
[0023] FIG. 4 shows a cross sectional view of obturator 15
revealing that the obturator 15 has an exterior hexagonal shape 17
with external sides 21a-f. For reference purposes the distance from
the geometric center of the obturator 15 to a flat located between
adjacent corners is designated by R.sub.4 and the distance from the
geometric center to a corner located between adjacent flats is
designated by R.sub.5 with R.sub.5 being greater than R.sub.4.
[0024] To illustrate the interrelation of the obturator 15 and the
cannula 13 reference should be made to FIG. 4A which shows a cross
section view taken along lines 4A-4A of FIG. 2A revealing the
obturator 15 having its outer surfaces 21a-f located in a spaced
condition from the inner web faces 14a-f of the polygonal tube 13.
In this example the obturator dimensions R.sub.4 and R.sub.5 are
respectively less than the cannula dimensions R.sub.1 and R.sub.2
such that the obturator is slidably disposed within cannula 13. On
the other hand the differences in the dimensions are sufficiently
small so that the obturator outer web surfaces 21a-f are
rotationally engageable with the cannula interior web faces of
14a-f to enable a surgeon to simultaneously rotate the trocar
assembly 20 i.e. the cannula 13 and the obturator 15, as a unit as
the cannula 13 and obturator 15 are forced through a patients body
tissue and into the body cavity of the patient.
[0025] FIG. 6 is a cross sectional view of the trocar assembly 19
of FIG. 2B taken along lines 6-6 to illustrate in isolated form a
feature of the invention that minimizes the trauma to a patient
during a medical procedure as well as maintaining a medical
instrument 36 in proper alignment within the cannula 13. In the
example shown the circular medical instrument 32 has a diameter
2R.sub.6 which is sufficiently less than a web to web dimension
2R.sub.1 of the cannula 13 (shown in FIG. 3) so that the surgical
instrument 36 is both axially slideable and rotationally
positionable within the lumen 20 in cannula 13.
[0026] Typically, the dimensional differences may be on the order
of a few thousands of an inch. As can be seen by the FIG. 6 the
coaction between the exterior surface 36a of instrument shaft 36
and the interior web faces 14a-f creates a set of triangular shaped
peripheral insufflation gas passages 30a-f that are located at the
junction of adjacent web faces. In addition, the web faces 14a-f
form a centering guide for maintaining the instrument 36 in axial
alignment with a central axis of the cannula 13 to minimize trocar
seal breakdown and consequent pressure loss between the surgical
instrument and the cannula since less stress is placed on a trocar
seal, which surrounds the medical instrument to seal and prevent
insufflation gas from escaping through the trocar. As can be seen
in FIG. 6 the difference in the cross sectional shape between the
cylindrical instrument shaft 36 and the hexagonal cannula 13
creates a set of triangular shaped peripheral fluid passages 30a-f
therebetween that allows the presence of both fluid flow and a
medical instrument within the lumen of the cannula 13. In this
example the internal web faces 14a-f of cannula 13 provide guides
for maintaining the shaft 36 in a central location in lumen 20.
That is, the web faces 14a-f limit shaft 36 from becoming
misaligned or askewed within the lumen 20 of cannula 13, a feature
which inhibits the accidental disturbance of a trocar seal between
the shaft 36 of the medical instrument and the trocar housing 10
since less stress is placed on the seal, however, it also ensures
that, each of the set of peripheral flow passages 30a-f remain open
for fluid flow therethrough since the dissimilar shape of the
cylindrical shaft 36 and the hexagonal cannula 13 prevent any of
the peripheral passages from being blocked by shaft 36 if the shaft
is located in an askew position within the lumen in cannula 13
since the shaft 36 is centrally constrained by web faces 14a-f.
[0027] A reference to FIG. 7, which is taken along lines 7-7 of
FIG. 5 reveals the relationship between cylindrical medical
instrument 36 and a second hexagonal shaped cannula 48. The cannula
48 is similar to the hexagonal cannula 13 of FIG. 1 except the
corners of cannula 48 are radiused and the cannula webs 45a-f are
not flat but concave inward. FIG. 7 also reveals a plastic flow of
body tissue 39a around the exterior hexagonal surface of the
cannula 48. That is, the varying radial dimensions of polygonal
cannula 48 allow the body tissue 39a to flow away from points of
high stress at the corners 46a-f of the polygonal shaped cannula 48
to areas of lower stress adjacent the webs 45a-f of the cannula 48,
a feature not found in a cannula having a circular cross sectional
shape since the tissue surrounding the circular cannula remains in
the same high stressed condition all 360 degrees around the
periphery of a circular cannula.
[0028] FIG. 7 shows the dimension from the geometric center of the
shaft 36 to the outer cylindrical surface is designated by R.sub.6
with R.sub.6 having a dimension less than the polygonal cannula
dimension R.sub.1 to enable the medical instrument shaft 36 to be
slideable disposed within the polygonal cannula 48 and at the same
time provide a set of peripheral fluid passages 47a-f located in a
spaced condition around the periphery surface 36a of the shaft 36
with the largest dimensions of the passages located at the junction
of adjacent webs.
[0029] If both the cannula and the medical instrument contain a
similar cross sectional shape, i.e. such as a circular
configuration, the medical instrument and the cannula coact to form
an annular fluid passage between the interior surface of the
cannula and the exterior surface of the medical instrument. In such
a trocar assembly the medical instrument can become skewed with
respect to a central axis of the cannula which also distorts the
annular flow passage introducing lateral fluid flow as well as
axial fluid flow around the medical instrument, which can result in
increased pressure losses due to an extended flow path past the
medical instrument. However, by maintaining the peripheral passages
in an open condition through the use of a dissimilar shape of a
medical instrument and a cannula one prevents shutting off axial
flow along a portion of the medical instrument thus limiting
pressure losses due to the lateral flow between the cannula and the
medical instrument. Consequently, if pressure losses due to lateral
flow are eliminated one can use a cannula with a smaller cross
sectional area than if the cannula and the medical instrument had a
similar shape. Thus a feature of a cannula and a medical instrument
having dissimilar shapes is that one minimizes pressure losses due
to minimizing or eliminating lateral or circumferential flow around
the medical instrument since the peripheral longitudinal flow
passages remain in an open condition regardless of the position of
the medical instrument in the cannula.
[0030] The use of a polygonal shape cannula allows one to minimize
trauma to a patient in relation to a conventional "oversized"
circular cannula. As used herein the term "oversized" cannula
refers to a cannula having a circular cross section, which is used
with a medical instrument having a circular cross section to form
an annular insufflation gas passage along the medical instrument.
To minimize pressure losses in the cannula and maintain a body
cavity in an inflated condition the cross sectional area of the
annular passage must be sufficiently large so that the pressure
losses or the velocity of the insufflating gas flowing past the
medical instrument remain relatively constant as the annular
passage becomes distorted or partially blocked off as the medical
instrument is periodically skewed with respect to a central axis of
the lumen. Since skewing of the medical instrument occurs during
the medical procedure the medical instrument skewing can increase
the flow resistance and the velocity of the insufflation gas in the
cross sectional area. To avoid pressure losses the annular passage
is normally maintained larger i.e. "oversized" than if the medical
instrument were to remain in a central location within the
cannula.
[0031] A benefit of the polygonal shape cannula is that it can
eliminate or inhibit pressure losses due to skewing of a medical
instrument, which allows one to have a polygonal shaped cannula
with a smaller cross sectional area than a circular cannula. A
further feature of the polygonal cannula is that it also minimizes
trauma to the patient since the polygonal cannula does not spread
the insertion site tissue as greatly as a cylindrical oversized
cannula even though each cannula may have the same maximum radial
dimension. That is, a polygonal shaped cannula is able to allow the
tissue to expand or flow laterally between the lobes or radi used
corners which are located on the outside of the cannula thus
limiting the tissue trauma around the cannula.
[0032] Thus, the use of a cannula having a different cross
sectional shape than the medical instrument minimizes the pressure
losses in comparison to the pressure losses occurring in a trocar
where the cannula and the medical instrument have the same cross
sectional shape.
[0033] Typically, most laparoscopic medical instruments have a
round cross section, and are sized such that they fit into a
targeted oversized circular cannula. By designing the cannula to
have a shape that contains elongated peripheral flow passages that
can maintain axial peripheral fluid around the exterior of the
medical instrument even though the medical instrument may become
skewed with respect to the axis of the cannula minimizes the
pressure losses that occur with an oversized cannula. Thus a
feature of the invention is that it eliminates the need for an
oversized circular cannula and hence the disadvantages of an
oversized circular cannula.
[0034] An advantage of a non-circular lumen cross section versus an
"oversized" circular cross section is that the faces of the
polygonal cannula coact to constrain or center a circular medical
instrument within a lumen in the cannula, thus allowing the
internal peripheral fluid passages in the cannula to continually
remain open to gas flow therethrough.
[0035] An additional benefit for concentrically restraining a large
medical instrument, within a noncircular cannula as opposed to
having both a circular cross section of the instrument and a
circular cross section of an oversized lumen, is the positive
effect on the trocar seal located between the medical instrument
and the trocar since the seal remains concentrically positioned
around the cannula. Often times an instrument with a circular cross
section, which is contained within an oversized cannula having a
circular lumen can become canted or skewed with respect to a
central axis of the cannula and the cannula seal which can stress
the seal therebetween which may cause seal failure or reduced seal
performance.
[0036] In the examples shown the cannula has a hexagonal shape with
radiused corners and webs located between the radiused corners. In
one case the webs are flat panels and in another case the webs have
a concave shape. While a hexagonal shaped cannula is a preferred
polygonal shape cannula other polygonal shaped cannulas of three or
more sides may be used where the cross sectional shape is different
from the cross sectional shape of the medical instrument without
departing from the spirit and scope of the invention. In addition,
medical instruments having an elliptical cross sectional shape may
also be used to concentrically support the medical instrument
therein while providing multiple longitudinal fluid passages along
peripheral regions of the cannula. While laparoscopic procedures
can be performed the trocar and cannula can be adapted for other
forms of endoscopic surgery and is not limited to laparoscopic
surgery.
* * * * *