U.S. patent application number 11/201401 was filed with the patent office on 2006-05-25 for shape lockable apparatus and method for advancing an instrument through unsupported anatomy.
This patent application is currently assigned to USGI Medical Inc.. Invention is credited to Richard C. Ewers, Vahid Saadat.
Application Number | 20060111614 11/201401 |
Document ID | / |
Family ID | 29741015 |
Filed Date | 2006-05-25 |
United States Patent
Application |
20060111614 |
Kind Code |
A1 |
Saadat; Vahid ; et
al. |
May 25, 2006 |
Shape lockable apparatus and method for advancing an instrument
through unsupported anatomy
Abstract
Apparatus and methods are provided for placing and advancing a
diagnostic or therapeutic instrument in a hollow body organ of a
tortuous or unsupported anatomy, comprising a handle, an overtube
disposed within a hydrophilic sheath, and a distal region having an
atraumatic tip. The overtube may be removable from the handle, and
have a longitudinal axis disposed at an angle relative to the
handle. The sheath may be disposable to permit reuse of the
overtube. Fail-safe tensioning mechanisms may be provided to
selectively stiffen the overtube to reduce distension of the organ
caused by advancement of the diagnostic or therapeutic instrument.
The fail-safe tensioning mechanisms reduce the risk of
reconfiguration of the overtube in the event that the tension
system fails, and, in one embodiment, rigidizes the overtube
without substantial proximal movement of the distal region. The
distal region permits passive steering of the overtube caused by
deflection of the diagnostic or therapeutic instrument, while the
atraumatic tip prevents the wall of the organ from becoming caught
or pinched during manipulation of the diagnostic or therapeutic
instrument.
Inventors: |
Saadat; Vahid; (Saratoga,
CA) ; Ewers; Richard C.; (Fullerton, CA) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
USGI Medical Inc.
San Clemente
CA
|
Family ID: |
29741015 |
Appl. No.: |
11/201401 |
Filed: |
August 9, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10281426 |
Oct 25, 2002 |
6960162 |
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11201401 |
Aug 9, 2005 |
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10173203 |
Jun 13, 2002 |
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10281426 |
Oct 25, 2002 |
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10173227 |
Jun 13, 2002 |
6790173 |
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10281426 |
Oct 25, 2002 |
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10173238 |
Jun 13, 2002 |
6837847 |
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10281426 |
Oct 25, 2002 |
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10173220 |
Jun 13, 2002 |
6783491 |
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10281426 |
Oct 25, 2002 |
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Current U.S.
Class: |
600/140 ;
600/129 |
Current CPC
Class: |
A61B 1/0052 20130101;
A61B 1/31 20130101; A61B 1/00135 20130101; A61B 1/008 20130101;
A61B 1/00105 20130101; A61B 1/00078 20130101; A61B 1/0058 20130101;
A61B 1/0055 20130101; A61B 1/00082 20130101; A61B 1/32 20130101;
A61B 1/00154 20130101; A61B 1/0008 20130101 |
Class at
Publication: |
600/140 ;
600/129 |
International
Class: |
A61B 1/00 20060101
A61B001/00 |
Claims
1. (canceled)
2. A disposable sheath configured to be disposed upon an overtube,
comprising: an outer skin having a distal end, a proximal end, and
a length configured to be disposed along an outer surface of the
overtube; a liner disposed within a lumen of the outer skin and
having a distal end, a proximal end, and a length configured to be
positioned through a lumen of the overtube; and an atraumatic tip
attached to at least one of the distal ends of the outer skin or
the liner.
3. The sheath of claim 2, wherein the sheath is removable from the
overtube.
4. The sheath of claim 2, wherein the length of the outer skin
extends over a length of the overtube.
5. The sheath of claim 2, wherein the outer skin comprises a
flexible elastomeric material.
6. The sheath of claim 5, wherein the elastomeric material
comprises silicone or synthetic rubber.
7. The sheath of claim 2, wherein the outer skin has a thickness of
less than 0.13 mm.
8. The sheath of claim 2, wherein the liner has a thickness of
about 0.15 mm.
9. The sheath of claim 2, wherein the outer skin and the liner
define an annular chamber within which the overtube is
inserted.
10. The sheath of claim 2, further comprising a kink-resistant coil
encapsulated within the liner.
11. The sheath of claim 2, wherein the liner is adapted to be
lubricious.
12. The sheath of claim 2, wherein the liner comprises a
hydrophilic coating thereon.
13. The sheath of claim 2, wherein the atraumatic tip is disposed
at the distal end of the liner.
14. A disposable sheath configured to be disposed upon an overtube,
comprising: an outer skin having a distal end, a proximal end, and
a length configured to be disposed along an outer surface of the
overtube; and a liner disposed within a lumen of the outer skin and
having a distal end, a proximal end, and a length configured to be
positioned through a lumen of the overtube, wherein the distal end
of the liner is attached to a distal end of the outer skin.
15. The sheath of claim 14, wherein the sheath is removable from
the overtube.
16. The sheath of claim 14, wherein the length of the outer skin
extends over a length of the overtube.
17. The sheath of claim 14, wherein the outer skin comprises a
flexible elastomeric material.
18. The sheath of claim 17, wherein the elastomeric material
comprises silicone or synthetic rubber.
19. The sheath of claim 14, wherein the outer skin has a thickness
of less than 0.13 mm.
20. The sheath of claim 14, wherein the liner has a thickness of
about 0.15 mm.
21. The sheath of claim 14, wherein the outer skin and the liner
define an annular chamber within which the overtube is
inserted.
22. The sheath of claim 14, further comprising a kink-resistant
coil encapsulated within the liner.
23. The sheath of claim 14, wherein the liner is adapted to be
lubricious.
24. The sheath of claim 14, wherein the liner comprises a
hydrophilic coating thereon.
25. The sheath of claim 14, further comprising an atraumatic tip
attached to at least one of the distal ends of the outer skin or
the liner.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/281,426 (Attorney Docket No.
021496-002210US), filed Oct. 25, 2002, which was a
continuation-in-part of U.S. patent application Ser. No. 10/173,203
(Attorney Docket No. 021496-002000US), Ser. No. 10/173,227
(Attorney Docket No. 021496-002300US), Ser. No. 10/173,238
(Attorney Docket No. 021496-002400US) and Ser. No. 10/173,220
(Attorney Docket No. 021496-002200US), all of which were filed Jun.
13, 2002 and are incorporated herein by reference in their
entireties.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The present invention relates to apparatus and methods for
placing and advancing a diagnostic or therapeutic instrument in a
hollow body organ of unsupported anatomy, while reducing patient
discomfort and risk of injury.
[0003] The use of the colonoscope for examining the interior of the
large intestine or colon is well-known. In general, a physician
performing an examination or treatment of the colon inserts a
colonoscope into the anus and then advances the colonoscope into
the colon. A complete examination requires the physician to advance
the colonoscope into the colon, negotiate the sigmoid colon, and
left and right colic flexures up to the cecum. Advancement of the
colonoscope is generally accomplished by manipulation of a
steerable tip of the colonoscope, which is controlled at the
proximal end of the device by the physician, in addition to
torquing and pushing the scope forward or pulling it backward.
[0004] Problems regularly occur, however, when negotiating the
colonoscope through the bends of the colon, such as at the sigmoid
and left and right colic flexures. These problems arise because the
colon is soft and has unpredictable fixation points to the viscera
of the abdomen, and it is easily distensible. Consequently, after
the steerable tip of the colonoscope is deflected to enter a new
region of the colon, the principal direction of the force applied
by the physician urging the proximal end of the device into the
patient's colon is not in the direction of the steerable tip.
Instead, the force is directed along the axis of the colonoscope
towards the preceding bend(s), and causes yielding or displacement
of the colon wall.
[0005] The loads imposed by the colonoscope on the colon wall can
have a myriad of possible effects, ranging from patient discomfort
to spastic cramp-like contractions of the colon and even possible
perforation or dissection of the colon. Consequently, the
colonoscope cannot be advanced as far as the cecum in up to
one-sixth of all cases.
[0006] To address some of these difficulties, it is known to employ
a guide tube that permits a colonoscope to be advanced through the
rectum. One such device is described in U.S. Pat. No. 5,779,624 to
Chang. An alternative approach calls for inserting the colonoscope
through a curved region, and then mechanically actuating the
portion of the device in the curved region to cause it to
straighten, as described in U.S. Pat. No. 4,601,283 to Chikama.
[0007] Many patients find the operation of such previously-known
devices unpleasant because the sigmoid portion of the colon is
forced into an almost rectilinear shape by the guide tube. Due to
the stiffness of the guide tube, careless handling of the guide
tube presents a risk of injury to the colon.
[0008] Other previously-known apparatus and methods use an overtube
having variable rigidity, so that the overtube may be inserted
through curved anatomy in a flexible state, and then selectively
stiffened to resist bending forces generated by passing a
colonoscope through the overtube. One example of such a device is
described in U.S. Pat. No. 5,337,733 to Bauerfiend. The device
described in that patent comprises inner and outer walls having
opposing ribs spaced apart across an air-filled annulus. The ribs
are selectively drawn together to intermesh, and form a rigid
structure by evacuating the annulus.
[0009] Another previously-known endoscopic device for delivering
aneurysm clips within a hollow organ or vessel is described in U.S.
Pat. No. 5,174,276 to Crockard. The device described in that patent
includes a conduit formed from a multiplicity of elements that are
capable of angulation relative to one another, and which becomes
rigid when subjected to a tensile force. The device is described as
being particularly useful in neurosurgery, where the variable
rigidity of the device is useful for providing a stable platform
for neurosurgical interventions, such as clipping an aneurysm.
[0010] While previously-known apparatus and methods provide some
suggestions for solving the difficulties encountered in advancing
diagnostic or therapeutic instruments through easily distensible
body organs, few devices are commercially available. Although the
precise reasons for this lack of success are uncertain,
previously-known devices appear to pose several problems.
[0011] For example, the devices described in the Bauerfiend and
Crockard patents appear to pose a risk of capturing or pinching
tissue between the endoscope/colonoscope and the distal end of the
overtube or conduit when the scope is translated. Also, neither
device provides any degree of steerability, and must be advanced
along the pre-positioned scope. In addition, the bulk of the
proximal tensioning system described in Crockard is expected to
interfere with manipulation of the endoscope. Other drawbacks of
previously-known devices may be related to the complexity or cost
of such devices or the lack of suitable materials. In any event,
there exists an un-met need for devices to solve this long-felt
problem in the field of endoscopy and colonoscopy.
[0012] In view of the foregoing, it would be desirable to provide
apparatus and methods for facilitating placement of diagnostic or
therapeutic instruments within easily distensible hollow body
organs, such as the esophagus or colon.
[0013] It further would be desirable to provide apparatus and
methods that permit a diagnostic or therapeutic device to be
advanced into a hollow body organ, and which facilitates passage of
the device through tortuous anatomy without requiring straightening
of organ passageways already traversed.
[0014] It also would be desirable to provide apparatus and methods
for facilitating placement of diagnostic or therapeutic instruments
within easily distensible hollow body organs that include means for
reducing the risk that tissue will become inadvertently pinched
between the apparatus and the advancing or withdrawing instrument,
or caught as the diagnostic or therapeutic instrument is maneuvered
through the hollow body organ.
[0015] It still further would be desirable to provide apparatus and
methods that provide a low-cost, single use, easily manufacturable
guide for inserting a diagnostic or therapeutic instrument in a
hollow body organ.
[0016] It yet further would be desirable to provide apparatus and
methods that provide a low-cost, easily manufacturable guide for
inserting a diagnostic or therapeutic instrument in a hollow body
organ, wherein a portion of the apparatus is disposable after a
single use and a remaining portion of the device is re-usable.
[0017] Still further, it would be desirable to provide a device
having a selectively locking shape for inserting a diagnostic or
therapeutic instrument in a hollow body organ, but which
facilitates manipulation of a proximal end of the diagnostic or
therapeutic instrument.
[0018] It additionally would be desirable to permit multiple
diagnostic or therapeutic devices to be positioned in a hollow,
unsupported organ, so that at least one of the devices may be
withdrawn and repositioned while the other devices are retained in
place.
[0019] It further would be desirable to provide apparatus and
methods for facilitating placement of diagnostic or therapeutic
instruments within easily distensible hollow body organs that
reduces the risk of reconfiguration of the apparatus in the event
of failure of the device.
[0020] It yet further would be desirable to provide apparatus and
methods for facilitating placement of diagnostic or therapeutic
instruments within easily distensible hollow body organs that
substantially maintains an axial length of the apparatus.
BRIEF SUMMARY OF THE INVENTION
[0021] In view of the foregoing, it is an object of the present
invention to provide apparatus and methods for facilitating
placement of diagnostic or therapeutic instruments within easily
distensible or unpredictably supported hollow body organs, such as
the esophagus or colon.
[0022] It is a further object of the present invention to provide
apparatus and methods that permit a diagnostic or therapeutic
device to be advanced into a hollow body organ, and which
facilitates passage of the device through tortuous anatomy without
requiring straightening of organ passageways already traversed.
[0023] It also is an object of the present invention to provide
apparatus and methods for facilitating placement of diagnostic or
therapeutic instruments within easily distensible hollow body
organs that include means for reducing the risk that tissue will
become inadvertently pinched or caught as the diagnostic or
therapeutic instrument is maneuvered through the hollow body
organ.
[0024] It is a still further object of the present invention to
provide apparatus and methods that provide a low-cost, single use,
easily manufacturable guide for inserting a diagnostic or
therapeutic instrument in a hollow body organ.
[0025] It is another object of this invention to provide apparatus
and methods that provide a low-cost, easily manufacturable guide
for inserting a diagnostic or therapeutic instrument in a hollow
body organ wherein a portion of the apparatus is disposable after a
single use and a remaining portion of the device is re-usable.
[0026] Still further, it is an object of the present invention to
provide a device having a selectively locking shape for inserting a
diagnostic or therapeutic instrument in a hollow body organ, but
which facilitates manipulation of a proximal end of the diagnostic
or therapeutic instrument.
[0027] It is yet another object of the present invention to permit
multiple diagnostic or therapeutic devices to be positioned in a
hollow, unsupported organ, so that at least one of the devices may
be withdrawn and repositioned while the other devices are retained
in place.
[0028] It is a further object of the present invention to provide
apparatus and methods for facilitating placement of diagnostic or
therapeutic instruments within easily distensible hollow body
organs that reduces the risk of reconfiguration of the apparatus in
the event of failure of the device.
[0029] It is a still further object of the present invention to
provide apparatus and methods for facilitating placement of
diagnostic or therapeutic instruments within easily distensible
hollow body organs that substantially maintains an axial length of
the apparatus.
[0030] These and other objects of the present invention are
attained by providing apparatus comprising a proximal handle, an
overtube coupled to the proximal handle and having a distal region,
an atraumatic tip disposed on the distal region, and mechanisms for
selectively locking the shape of the overtube to assist one or more
diagnostic or therapeutic instruments to negotiate the tortuous or
unsupported anatomy of a hollow body organ, rather than distending
the wall of the organ. The apparatus includes a main lumen
extending between the handle, overtube and atraumatic tip, through
which a diagnostic or therapeutic instrument, such as an endoscope
or colonoscope, may be translated.
[0031] The handle extends from the patient, e.g., through the mouth
or anus, where it can be manipulated by the physician. The proximal
handle may form part of a single use, disposable apparatus, or may
be separable from the overtube and reusable. Alternatively, the
overtube may include a disposable single-use cover that fits over a
reusable structure. The overtube may be angled relative to a
working axis of the handle, so that the handle does not interfere
with manipulation of the diagnostic or therapeutic instrument
inserted through the overtube.
[0032] An overtube constructed in accordance with the principles of
the present invention may comprise a multiplicity of nested
elements that are selectively tensionable by actuation of a
ratchet, a pneumatic mechanism, or shape memory materials.
Alternatively, the overtube may include a series of interconnected
links surrounded by a selectively actuable clamping mechanism, a
tubular member comprising a multiplicity of helical links formed
from a material having variable durometer and surrounded by a
clamping mechanism, a thermoresponsive polymer or alloy, an
elongate, flexible tube made from an electroactive polymer, or a
series of overlapping or nested links that are made from a shape
memory material. The overtube may include any of a number of aids
for facilitating passage of the diagnostic or therapeutic
instrument through the main lumen, including a lubricious liner,
rails or rollers.
[0033] The tensioning systems may provide a fail-safe mode that
reduces the risk of reconfiguration of the overtube in the event
that the mechanism fails. The fail-safe mode may equalize
compressive clamping loads applied to the overtube when the
overtube is rigidized, and be configured to rigidize the overtube
without substantial proximal movement of the distal region.
[0034] The liner may be made from thin, flexible material, have a
hydrophilic coating, incorporate a kink-resistant coil, or
combinations thereof. Alternatively, the liner may be a disposable
sheath that may be removed from the overtube to permit re-use of
the internal structure of the overtube.
[0035] The atraumatic tip of the present invention preferably is
configured to reduce the risk of capturing or pinching tissue
between the overtube and a diagnostic or therapeutic instrument
that is selectively translated through the overtube. This is
preferably accomplished by the atraumatic tip applying a
radially-outwardly directed load to the wall of the hollow body
organ in the vicinity of the distal region where the diagnostic or
therapeutic instrument exits the apparatus.
[0036] In addition, the distal region of the overtube preferably
includes a flexible portion that permits a steerable tip of a
diagnostic or therapeutic device disposed within the distal region
to deflect the distal region of the overtube in a desired
direction. This permits the overtube to be readily advanced
together with the steerable tip of the diagnostic or therapeutic
device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Further features of the invention, its nature and various
advantages will be more apparent from the accompanying drawings and
the following detailed description of the preferred embodiments, in
which:
[0038] FIG. 1 is a schematic view of a human colon illustrating a
common difficulty encountered in advancing a colonoscope beyond the
sigmoid colon;
[0039] FIG. 2 is a side view of illustrative apparatus of the
present invention;
[0040] FIG. 3A is a side-sectional exploded view of nestable
elements of a first embodiment of an overtube suitable for use in
the apparatus of FIG. 2;
[0041] FIG. 3B is a side view of two of the nestable elements of
FIG. 3A nested together;
[0042] FIG. 4 is a side-sectional view of a distal region of the
apparatus of FIG. 2 constructed in accordance with principles of
the present invention;
[0043] FIG. 5 is a side-sectional view of an illustrative
arrangement of a mechanism suitable for use in the handle of the
apparatus of FIG. 2;
[0044] FIG. 6 is a side-sectional view of the detail of a wire
clamping system suitable for use in the handle of FIG. 5;
[0045] FIGS. 7A-7C are schematic views of a method of using the
apparatus of the present invention;
[0046] FIG. 8 is a schematic view of an alternative step in the
method of using the apparatus of the present invention;
[0047] FIG. 9 is a side view of an alternative embodiment of the
apparatus of the present invention;
[0048] FIGS. 10A-10C are schematic views of components of a
tensioning mechanism suitable for rigidizing the overtube of the
present invention, wherein the components provide a fail-safe
mode;
[0049] FIG. 11 is a cut-away side view of a tensioning mechanism
incorporating the components of FIGS. 10A and 10B within the handle
of the apparatus of FIG. 2;
[0050] FIGS. 12A-12D are schematic perspective views of alternative
components of a tensioning mechanism that each provide a fail-safe
mode;
[0051] FIGS. 13A and 13B are, respectively, a side sectional view
of a tensioning mechanism incorporating the pulley manifold of FIG.
12B within the handle of the apparatus of FIG. 2, and an indicator
that displays the status of the overtube;
[0052] FIGS. 14A-14C are cut-away side views of an alternative
tensioning mechanism that transitions the overtube of the present
invention between flexible and rigid states with successive
actuations;
[0053] FIG. 15 is a side sectional view of yet another alternative
tensioning mechanism employing pneumatic actuation;
[0054] FIG. 16 is a side sectional view of a further alternative
tensioning system that transitions the overtube of the present
invention from a flexible state to a rigid state without
substantial movement of a distal end of the overtube;
[0055] FIGS. 17A and 17B, respectively, are a side-section view of
an alternative element suitable for use in the overtube of FIG. 2
and a roller element suitable for use with the element of FIG. 17A,
respectively;
[0056] FIGS. 18A and 18B depict the use of lubricious rails in the
overtube of the apparatus of FIGS. 2 or 9 to facilitate passage of
a diagnostic or therapeutic device through the main lumen;
[0057] FIG. 19 is a side-sectional view of an alternative nestable
element having an integral lubricious lining;
[0058] FIGS. 20A and 20B are side-sectional views of alternative
nestable elements that form a smooth internal lumen when nested
together;
[0059] FIGS. 21A-21D are still further alternative embodiments of
the nestable elements of FIG. 3, in which the nestable elements are
macroscopically textured to enhance friction;
[0060] FIG. 22 is a schematic view of the lumen of the overtube of
the present invention depicting the use of multiple devices;
[0061] FIGS. 23-28 depict side-sectional views of various
alternative embodiments of an atraumatic tip constructed in
accordance with the present invention;
[0062] FIGS. 29 and 30 are alternative embodiments of the overtube
of the present invention, having tensioning systems that employ
shape memory materials;
[0063] FIGS. 31A-31C are, respectively, a side-sectional view of an
alternative embodiment of an overtube suitable for use in the
present invention having a multiplicity of interconnected links
surrounded by a clamping sleeve, and cross-sectional views of
portions of the sleeve;
[0064] FIG. 32 is a side-sectional view of a further alternative
embodiment of an overtube constructed in accordance with the
present invention having a spiral bladder to actuate the clamping
links;
[0065] FIG. 33 is a side-sectional view of another alternative
embodiment of an overtube of the present invention having
thermally-actuable bands;
[0066] FIGS. 34A and 34B are side-sectional views of a yet further
alternative embodiment of an overtube of the present invention
comprising a series of helical links having regions of different
durometer;
[0067] FIG. 35 is a side-sectional view of a still further
alternative embodiment of an overtube suitable for use with the
present invention comprising a series of links having proximal and
distal rims that interlock;
[0068] FIG. 36 is a side-sectional view of another alternative
embodiment of the present invention comprising a series of links
that form coacting joints;
[0069] FIG. 37 is a side-sectional view of yet another alternative
embodiment of an overtube having thermally regulated stiffness;
[0070] FIGS. 38A-38C are schematic views of yet another alternative
embodiment of an overtube suitable for use with the present
invention, in which the diameters of tension wire lumens extending
through the overtube vary responsive to electrical
energization;
[0071] FIG. 39 is a side-sectional view of still another
alternative embodiment of an overtube having a series of
electrically activated links disposed in an overlapping fashion
around a series of rigid links;
[0072] FIGS. 40A and 40B are side-sectional views of, respectively,
an electrically activated nestable link and a plurality of the
electrically activated nestable link of FIG. 40A nested together to
form an overtube suitable for use with the apparatus of the present
invention;
[0073] FIG. 41 is a side-sectional view of a disposable sheath for
use with the overtube of the present invention; and
[0074] FIG. 42 is a schematic side view of a strap that couples the
apparatus of the present invention to a colonoscope.
DETAILED DESCRIPTION OF THE INVENTION
[0075] Referring to FIG. 1, problems associated with
previously-known apparatus and methods for inserting and advancing
a diagnostic or therapeutic instrument into a hollow body organ
having tortuous or unsupported anatomy, illustratively, patient's
colon C, are described. Colon C includes sphincter muscle SM
disposed between anus A and rectum R. Rectum R is coupled via the
rectosigmoid junction RJ to sigmoid colon SC. Sigmoid colon SC
joins descending colon DC, which in turn is coupled to transverse
colon TC via left colic flexure LCF. Transverse colon TC also is
coupled by right colic flexure RCF to ascending colon AC and cecum
CE, which receives waste products from the small intestine.
[0076] As illustrated in FIG. 1, colonoscope 10 having steerable
distal tip 11 is typically inserted through anus A into rectum R,
and then steered through rectosigmoid junction RJ into sigmoid
colon SC. As depicted in FIG. 1, distal tip 11 of colonoscope 10 is
advanced through sigmoid colon SC and deflected into descending
colon DC. Further urging of the colonoscope by the physician can
cause region 12 of the colonoscope to bear against and cause
displacement of the rectosigmoid junction RJ, as illustrated by
dotted lines 12' and RJ' in FIG. 1.
[0077] Such distension may result in patient discomfort or spasm,
and if unnoticed, could result in injury to the colon. The
potential for movement of colonoscope to cause distension,
discomfort or spasm is also great where the colonoscope must
negotiate left colic flexure LCF and right colic flexure RCP', and
results in a large portion of such examinations terminating before
the physician can advance distal tip 11 to cecum CE.
[0078] The present invention provides apparatus and methods for
placing a diagnostic or therapeutic instrument through the tortuous
or unpredictably supported anatomy of a hollow body organ, such as
the esophagus or colon, while reducing the risk of distending or
injuring the organ. Apparatus constructed in accordance with the
present invention permits an endoscope or colonoscope to be readily
advanced into a patient's tortuous or unsupported anatomy by
selectively shape-fixing an overtube portion of the apparatus,
while also preventing tissue from being captured or pinched between
the overtube and scope.
[0079] Referring now to FIG. 2, apparatus 20 of the present
invention is described. Apparatus 20 comprises handle 21, overtube
22, and distal region 23 having atraumatic tip 24. Handle 21
includes lumen 25 that extends from Toughy-Borst valve 26 through
overtube 22, distal region 23 and atraumatic tip 24. Lumen 25 is
configured to facilitate passage of a standard commercially
available colonoscope, such as colonoscope 10, therethrough.
Toughy-Borst valve 26 may be actuated to releasably lock
colonoscope 10 to apparatus 20 when colonoscope 10 is inserted
within lumen 25. As described hereinafter, overtube 22 is
configured so that it can be selectively transitioned between a
flexible state and a rigid, shape-fixed state by actuator 27
disposed on handle 21.
[0080] In FIG. 3A, illustrative embodiment of overtube 22 comprises
a multiplicity of nestable elements 30. For purposes of
illustration, nestable elements 30 are shown spaced-apart, but it
should be understood that elements 30 are disposed so that distal
surface 31 of one element 30 coacts with proximal surface 32 of an
adjacent element. Each of nestable elements 30 has central bore 33
to accommodate colonoscope 10, and preferably two or more tension
wire bores 35. When assembled as shown in FIG. 2, nestable elements
30 are fastened with distal and proximal surfaces 31 and 32
disposed in a coacting fashion by a plurality of tension wires 36
that extend through tension wire lumens 28 defined by tension wire
bores 35. Tension wires 36 preferably are made from a superelastic
material, e.g., nickel titanium alloy, to provide flexibility,
kink-resistance and smooth movement of the tension wires through
tension wire bores 35. Alternatively, the tension wires may be made
from braided stainless steel, a single stainless steel wire,
Kevlar, a high tensile strength monofilament thread, or
combinations thereof. These materials are provided only for the
sake of illustration and should in no way be construed as
limiting.
[0081] In a preferred embodiment, a ratio of the diameter of
tension wires 36 to the diameter of tension wire bores 35
approximately is in a range of 1/2 to 2/3. Applicants have observed
that this provides smooth relative movement between the tension
wires and the nestable elements, even when overtube 22 is
retroflexed. While a greater ratio is desirable, such a
configuration appears to cause the edges of tension wire bores 35
to gouge into tension wires 36, thereby constraining movement of
the tension wires through the tension wire bores. Conversely, while
applicants contemplate that a smaller ratio would provide even
smoother relative movement, the resultant increase in the thickness
of wall 34 of each nestable element 30 is undesirable.
[0082] In a preferred embodiment, adjacent surfaces 31 and 32 of
each nestable element 30 are contoured to mate with the next
adjacent element, so that when tension wires 33 are relaxed,
surfaces 31 and 32 can rotate relative to one another. Tension
wires 36 are fixedly connected to the distal end of overtube 22 at
the distal ends and to a tensioning mechanism disposed within
handle 21 at the proximal ends. When actuated by actuator 27,
tension wires 36 impose a load that clamps distal and proximal
surfaces 31 and 32 of nestable elements 30 together at the current
relative orientation, thereby fixing the shape of overtube 22.
[0083] When the load in tension wires 36 is released, tension wires
36 provides for relative angular movement between nestable elements
30. This in turn renders overtube 22 sufficiently flexible to
negotiate a tortuous path through the colon. When the tensioning
mechanism is actuated, however, tension wires 36 are retracted
proximally to apply a clamping load to the nestable elements. This
load prevents further relative movement between adjacent elements
30, and stiffens overtube 22 so that any distally directed force
applied to colonoscope 10 causes distal tip 11 to advance further
into the colon, rather than cause overtube 22 to bear against the
wall of the colon. The shape-fixed overtube absorbs and distributes
vector forces, shielding the colon wall.
[0084] In a preferred embodiment, the radius of curvature of
proximal surface 32 closely approximates the radius of curvature of
distal surface 31. In particular, a ratio of the radius of
curvature of distal surface 31 to that of proximal surface 32 is in
an approximate range of about 0.9 to 1.0. Furthermore, the
coefficient of static friction between the distal and proximal
surfaces preferably is in an approximate range of 0.2 to 1.4 (based
on ASTM standard D1894). This structure appears to permit
sufficient frictional force to develop between the surfaces to
prevent relative movement between adjacent elements when overtube
22 is rigidized.
[0085] Nestable elements 30 may be configured to provide a stack-up
of overtube 22 that is a function of the growth height. As defined
in FIG. 3B, growth height H is the increase in the longitudinal
length of overtube 22 when one nestable element 30 is nested within
another nestable element 30. To accommodate the radius of curvature
obtainable by standard commercially available colonoscopes, growth
height H preferably is less than or equal to about 0.31 in, and
more preferably about 0.16 in. This provides overtube 22 with
sufficient flexibility to assume a radius of curvature that is less
than or equal to approximately 0.95 in. If overtube 22 needs to
accommodate other endoscopes or medical instruments that are larger
or smaller in size and/or that may assume different radii of
curvature, or the overtube needs to accommodate tighter anatomical
constraints, applicants contemplate that growth height H may be
increased or decreased proportionate to the change in dimensions of
overtube 22. Applicants note that the preceding geometrical
characterization of nestable element 30 does not account for
material interference or effects to the tension wire bores, which
are omitted from FIG. 3B for illustrative purposes.
[0086] Nestable elements 30 preferably are molded from a polymer
filled with fibers of glass, carbon, or combinations thereof. In a
particularly useful embodiment, nestable elements 30 are molded
from polyurethane filled with 20-40% by volume of glass fibers,
20-40% by volume of carbon fibers, or 20-40% by volume of glass and
carbon fibers. One example is isoplast 2540, which is available
from Dow Chemicals, Midland, Mich. Applicants have observed that
such materials enhance friction between adjacent elements, which
advantageously reduces the risk of relative angular movement
between the adjacent elements when overtube 22 is stiffened and,
thus, reduces the risk of undesired reconfiguration of overtube 22
in its shape-locked state. While a greater amount of glass and/or
carbon fibers is desirable, such a material appears to reduce the
structural integrity of the nestable element.
[0087] Furthermore, fiber embedded polymers increase the rigidity
of nestable elements 30 so that longitudinal contraction of
overtube 22 is significantly reduced when the overtube is stiffened
Longitudinal contraction develops when tension wires 36 are
actuated to apply a compressive clamping load to overtube 22. The
resultant pressure eliminates any gaps between adjacent elements 30
and deflects the proximal portion of each nestable element radially
outward. This foreshortens each element in the longitudinal
direction, so that overtube 22 contracts in the axial length.
[0088] Typically, an overtube made from polymeric nestable elements
without inclusion of glass and/or carbon fibers will contract
approximately 8-12% in the longitudinal direction when a
compressive force of approximately 30 lbs is applied. By
comparison, when a compressive load of 30 lbs is applied to
nestable elements made from a glass and/or carbon fiber embedded
polymer, as in the preferred embodiment of the present invention,
the overtube only contracts approximately 4%. Advantageously, this
reduces trauma to the patient by providing greater accuracy during
use of the present invention, which is particularly important in
delicate procedures. In addition to glass and/or carbon filled
polymers, it will be apparent to one of ordinary skill in the art
that nestable elements 30 also may be molded or machined from other
polymers and/or metals, such as polyurethane, polyvinyl chloride,
polycarbonate, nylon, titanium, tungsten, stainless steel,
aluminum, or combinations thereof. Indeed, nestable elements 30
made from metals experience a longitudinal contraction even less
than that experienced by fiber embedded polymers. These materials
are provided only for the sake of illustration, and one of ordinary
skill in the art will recognize numerous additional materials that
are suitable for use with the apparatus of the present
invention.
[0089] Referring now to FIG. 4, an illustrative embodiment of
distal region 23 and atraumatic tip 24 is described. Distal region
23 comprises flexible, kink-resistant coil 41 encapsulated in
flexible layer 42. Layer 42 preferably comprises a soft elastomeric
and hydrophilic coated material, such as silicon or synthetic
rubber, and terminates at the distal end in enlarged section 44
that forms atraumatic tip 24. At the proximal end, layer 42 joins
with or is integrally formed with liner 43 that extends through
bores 33 of nestable elements 30 to handle 21. In a preferred
embodiment, liner 43 is made of a thin, flexible material
optionally having flexible, kink-resistant coil 29 embedded
therein. The material of liner 43 preferably has a high durometer
within the range of 30-80 D, but also may have a lower or higher
durometer.
[0090] Layer 42 preferably joins with or is integrally formed with
flexible elastomeric skin 45 to form sheath 48, which encapsulates
nestable elements 30 in annular chamber 46. Skin 45 provides a
relatively smooth outer surface for overtube 22, and prevents
tissue from being captured or pinched during relative rotation of
adjacent nestable elements 30. In a preferred embodiment, aggregate
thickness T of skin 45, nestable elements 30 and liner 43, is less
than or equal to approximately 2.5 mm, and more preferably less
than or equal to 1 mm. For example, skin 45 may have a thickness of
0.13 mm, or more preferably 0.1 mm, element 30 may have a thickness
of 1.9 mm, and more preferably 0.7 mm, and liner 43 may have a
thickness of 0.38 in, or more preferably 0.15 mm.
[0091] In accordance with one aspect of the present invention,
colonoscope 10 may be positioned with its distal tip 11 disposed in
distal region 23, so that deflection of steerable distal tip 11
imparts an angular deflection to distal region 23 and atraumatic
tip 24. To ensure that there is no gross relative motion between
colonoscope 10 and apparatus 20, Toughy-Borst valve 26 is tightened
to engage apparatus 20 to the colonoscope. In this manner,
colonoscope 10 and distal region 23 may be simultaneously advanced
through the colon, with the distal tip of the colonoscope providing
a steering capability to apparatus 20. Apparatus 20 therefore may
be advantageously advanced together with colonoscope 10 when
overtube 22 is in the flexible state, reducing relative motion
between apparatus 20 and colonoscope 10 to those instances where
overtube 22 must be shape-locked to prevent distension of the
colon.
[0092] Still referring to FIG. 4, terminations 47 of tension wires
are described. Terminations 47 illustratively comprise balls welded
or molded onto the ends of tension wires 36 that ensure the tension
wires cannot be pulled through tension wire bores 35 of the
distal-most nestable element 30. This ensures that the nestable
elements cannot come loose when overtube 22 is disposed within a
patient.
[0093] Alternatively, terminations 47 may comprise knots formed in
the ends of tension wires 36, or any suitable fastener that
prevents the tension wires from being drawn through the tension
wire bores of the distal-most nestable element. Advantageously,
skin 45 provides additional assurance that all of nestable elements
30 can be safely retrieved from a patient's colon in the unlikely
event of a tension wire failure.
[0094] Referring now to FIGS. 2 and 5, tension wires 36 within
overtube 22, liner 43 and lumen 25 extend from distal region 23,
through overtube 22, and to handle 21. Within handle 21, each
tension wire 36 passes through wire lock release 51 fixedly
attached to handle 21, and wire lock 52 disposed on slide block 53.
Each tension wire 36 terminates at wire tension spring 54, which
maintains tension wires 36 in light tension even when overtube 22
is in the flexible state. The degree of tension provided by wire
tension springs 54 is not sufficient to clamp adjacent nestable
elements 30 together, but on the other hand does not let gaps form
between adjacent nestable elements, and helps to manage the tension
wire take up or slack as overtube 22 makes various bends.
[0095] Slide block 53 is keyed to slide along rail 55 disposed
between limit blocks 56 and 57, and comprises a rigid block having
a bore through which rail 55 extends and an additional number of
bores as required for the number of tension wires 36 employed. Rack
gear 58 is fixedly coupled to slide block 53. Rack 58 mates with
pinion gear 59, which is in turn driven by bi-directional pawl 60
coupled to actuator 27. Pinion gear 59 may be selectively engaged
by either prong 61 or 62 of bi-directional pawl 60, depending upon
the position of selector switch 63.
[0096] If prong 61 is selected to be engaged with pinion gear 59, a
squeezing action applied to actuator 27, illustratively hand grip
64, causes rack 53 to move in the D direction in FIG. 5, thereby
applying tension to tension wires 36. Repeated actuation of band
grip 64 causes slide block 53 to move progressively further in
direction D, thereby applying an increasing clamping load on
nestable elements 30. Any slack lengths of tension wires 36
extending below slide block 53 are taken up by wire tension springs
54. As discussed in greater detail below with respect to FIG. 6,
wire locks 52, which are affixed to slide block 53, engage and
retract tension wires 36 concurrently with movement of slide block
53 in the D direction.
[0097] If prong 62 is instead chosen by selector switch 63 to
engage pinion gear 59, repeated actuation of hand grip 64 causes
slide block 53 to translate in direction U, thereby relaxing the
tensile load applied by tension wires 36 to nestable elements 30.
Repeated actuation of hand grip 64 causes slide block 53 to advance
in direction U until wire lock releases 51 engage wire locks 52,
releasing all tension from tension wires 36 except that provided by
wire tension springs 54. This action permits the clamping forces
imposed on nestable elements 30 to be progressively reduced and
render overtube 22 progressively move flexible, until when wire
lock releases 51 engage wire locks 52, the overtube is returned to
its most flexible state.
[0098] Referring to FIG. 6, wire lock 52 and lock release 51 are
described in greater detail. Wire lock 52 includes jaws 65 disposed
within collet 66. Collet 66 includes a tapered conical bore 67.
Jaws 65 have ramped exterior surfaces 68 and teeth 69, and are
biased against the surface formed by the tapered conical bore by
springs 70. Teeth 69 are configured to engage tension wire 36 under
the bias force of springs 70. When slide block 53 is moved in
direction D (see FIG. 5), jaws 65 engage and grasp tension wire 36
and retract the tension wire in direction D.
[0099] To disengage teeth 69 from tension wire 36, e.g., when it is
desired to allow overtube 22 to return to a flexible state, slide
block 53 is actuated as described previously to move in direction
U. Further actuation of slide block 53 towards limit block 56 and
wire lock release 51 causes wire lock release 51 to extend into
tapered conical bore 67 and push jaws 65 backward against the bias
of springs 70. Once tension wires 36 are freed from jaws 65,
overtube 22 returns to its most flexible state.
[0100] Referring to FIGS. 7A-7C, a method of using apparatus 20 is
described. Colonoscope 10 and overtube 22 may be inserted into the
patient either simultaneously or by first backloading the overtube
onto the colonoscope. To perform simultaneous insertion,
colonoscope 10 is introduced into lumen 25 of handle 21 until
distal tip 11 of the colonoscope is disposed in distal region 23.
Toughy-Borst valve 26 is actuated to lock apparatus 20 to
colonoscope 10. As one unit, colonoscope 10 and overtube 22 are
inserted into rectum R of the patient, and navigated about
rectosigmoid junction RJ. As discussed previously, steerable distal
tip 11 may be used to impart angular deflection to flexible tip 24
to steer tip 24 about tortuous curves, such as rectosigmoid
junction RJ. Once distal tip 11 and tip 24 have been negotiated
past rectosigmoid junction RJ, the current shape of overtube 22 is
locked in the manner discussed above to provide a rigid channel
through which colonoscope 10 may be further advanced into the colon
without distending rectosigmoid junction RJ. Once distal tip 11 of
colonoscope 10 is negotiated past sigmoid colon SC, overtube 22 is
released from its rigid state and advanced along colonoscope 10
until it too traverses sigmoid colon SC. Again, the current shape
of overtube 22 is locked to provide a rigid channel for advancement
of colonoscope 10. To negotiate the remainder of the colon, such as
left colic flexure LCF and right colic flexure RCF, the preceding
steps may be repeated. In this manner, colonoscope 10 and overtube
22 may be navigated through the tortuous curves of the colon
without distending the colon, and thereby causing discomfort, spasm
or injury.
[0101] Alternatively, rather than simultaneously inserting both
colonoscope 10 and overtube 22 into the patient, apparatus 20 first
may be backloaded onto the colonoscope. First, overtube 22 is
threaded onto colonoscope 10 and positioned proximal distal tip 11,
as shown in FIG. 8. Colonoscope 10 then is inserted into rectum R
of the patient and advanced around rectosigmoid junction RJ.
Overtube 22 is advanced along colonoscope 10 into rectum R of the
patient, using colonoscope 10 as a guide rail to negotiate
rectosigmoid junction RJ. Once overtube 22 traverses rectosigmoid
junction RJ to the position shown in FIG. 7A, the shape of overtube
22 is locked to provide a rigid channel through which colonoscope
10 may be further advanced into the colon. To negotiate the
remainder of the colon, the steps discussed in reference to FIGS.
7B-7C may be performed. [0101] With respect to FIG. 9, an
alternative embodiment of handle 21 is described. Like handle 21 of
FIG. 5, handle 71 also embodies a ratchet-type tension mechanism,
but in this embodiment overtube 22 may be separated from handle 71,
thereby permitting handle 71 to be sterilized for repeated use.
Handle 71 comprises housing 72 having actuator 73 that engages
teeth 74 disposed along the length of rod 75, which defines working
axis W of handle 71. Push knob 76 is affixed to the proximal end of
rod 75 so that when pawl 77 is released, rod 75 may be pushed in a
distal direction. Pawl 77 engages teeth 74 of rod 75 to prevent
distally-directed motion of rod 75. Spring 78 biases pawl 77
against teeth 74 of rod 75, to provide a one-way ratchet effect
when actuator 73 is squeezed.
[0102] As in the embodiment of FIG. 5, tension wires 36 extend
through wire lock releases 79, wire locks 80, and are coupled to
wire tension springs 81. Wire locks 80 are affixed to block 82,
which translates within housing 72 responsive to movement of rod
75. Wire locks 80 and wire lock releases 79 operate in the same
manner as described with reference to FIG. 6.
[0103] In operation, squeezing actuator 73, illustratively a hand
grip, causes fork 83 to move rod 75 in a proximal direction so that
pawl 77 captures the next distal-most tooth 74. This movement also
causes wire locks 80 to engage and grasp tension wires 36 and
retract the tension wires proximally. Further actuation of actuator
73 causes overtube 22 to stiffen in the manner previously
described. Spring 78 retains pawl 77 in continuous engagement with
teeth 74, thereby preventing rod 75 from moving in the distal
direction.
[0104] When it is desired to make overtube 22 more flexible, pawl
77 is released and knob 76 pushed in the distal direction so that
wire locks 80 engage wire lock releases 79. As described above,
this releases tension wires 36 from wire locks 80 and permits
overtube to assume its most flexible state.
[0105] In accordance with one aspect of the present invention,
overtube 22 of the embodiment of FIG. 9 may be replaceably removed
from yoke 84 of handle 71. In addition tension wires 36 further may
comprise connectors 85 that permit the tension wires to be
disconnected. Such a configuration permits the overtube to be
removed and discarded after a single use, while the handle may be
sterilized and reused.
[0106] Yoke 84 is also configured to position overtube 22 so that
longitudinal axis L of the overtube is angularly displaced from
working axis W by a predetermined angle #. This arrangement
prevents handle 71 from interfering with advancement of colonoscope
10 into lumen 25.
[0107] In accordance with yet another aspect of the present
invention, overtube 22 includes atraumatic tip 86 that comprises a
soft foam-like material. Atraumatic tip 86 not only facilitates
advancement of overtube 22 in traversing tortuous anatomy, but also
serves to retain the organ wall a safe distance away from the
opening through which the colonoscope is reciprocated by radially
expanding the organ wall in the vicinity of the tip, as described
hereinbelow with respect to FIG. 14A. Accordingly, atraumatic tip
86 reduces the potential for tissue to be caught or pinched in
lumen 25 when the colonoscope is manipulated.
[0108] Referring now to FIGS. 10-16, alternative tensioning
mechanisms are described, in which the tensioning mechanisms may
provide a fail-safe mode that reduces the risk of undesired
reconfiguration of the overtube in the event of tensioning
mechanism failure. When overtube 22 is in the rigid state, the
following tensioning mechanisms are configured to self-equalize
compressive loads applied to the multiplicity of nestable elements,
so that if, e.g., a tension wire breaks, the overtube either
softens into the flexible state or retains its shape-locked
state.
[0109] FIG. 10A schematically depicts components of a first
embodiment of an alternative tensioning mechanism having plurality
of distal pulleys 87 operably coupled via proximal tension wire 88.
Proximal tension wire 88 is slidably disposed within proximal
pulley 89. Each tension wire 90 couples adjacent tension wire
lumens 28, through respective distal pulleys 87. For example, if
four tension wire lumens 28a-28d are provided, as in FIG. 10A,
first tension wire 90a extends from tension wire lumen 28a to
adjacent tension wire lumen 28b through first distal pulley 87a.
Likewise, second tension wire 90b extends from tension wire lumen
28c to adjacent tension wire lumen 28d through second distal pulley
87b.
[0110] This configuration equalizes tension within tension wires
90, so that a proximally directed force F applied to proximal
pulley 89 is distributed evenly through tension wires 90. When one
of the tension wires breaks, this configuration allows overtube 22
to soften into its flexible state since the loss of tension in any
of the tension wires is transmitted through the pulley system to
the remaining tension wires.
[0111] It will be apparent to one of ordinary skill in the art that
tension wires 90a and 90b may comprise either two separate lengths
of wire, or a single length of wire that is looped backwards after
traversing the distal-most nestable element 30. Furthermore, while
FIG. 10A depicts tension wires 90 extending through adjacent
tension wire lumens 28, the tension wires instead may extend
through wire lumens disposed diametrically opposite each other, as
shown in FIG. 10B. Tension wires 90 preferably are made from a
superelastic material, e.g., nickel titanium alloy, but also may be
made from braided stainless steel, single stainless steel wires,
Kevlar, a high tensile strength monofilament thread, or
combinations thereof. These materials are provided only for the
sake of illustration and should in no way be construed as
limiting.
[0112] In an alternative embodiment illustrated in FIG. 10C,
proximal pulley 89 is eliminated, and distal pulleys 87 are fixed
to each other, e.g., by welding, so that a unitary pulley manifold
is formed. A proximally directed force F that is applied to the
pulley manifold is distributed evenly through tension wires 90 that
extend through respective distal pulleys 87 to diametrically
disposed tension wire lumens 28 within overtube 22. If tension
wires 90 comprise two separate lengths of wires, the risk of
reconfiguration of overtube 22 is reduced if one of the wires
breaks since the tension within the overtube, as defined by the
unbroken tension wire, is symmetrically balanced. If the remaining
tension wire breaks, the tension wire relaxes into the flexible
state. If tension wires 90 comprise a single length of wire that
breaks, the overtube immediately relaxes into the flexible state,
thereby also reducing the risk of undesired configuration of the
overtube in the event of tensioning system failure.
[0113] Furthermore, applicants have observed that the apparatus of
the present invention also may comprise only one distal pulley 87
coupled to overtube 22 via a single tension wire 90 disposed
through diametrically opposite tension wire lumens 28. When a
proximally directed force is applied to the single distal pulley,
the force is distributed through the single tension wire to impose
a symmetrical compressive clamping load on overtube 22 that is
sufficient to shape-lock the overtube. When tension wire 90 breaks,
overtube 22 immediately softens into its flexible state, thereby
reducing the risk of undesired reconfiguration of the overtube in
the event of tensioning system failure.
[0114] Referring now to FIG. 11, lumen 25 and tension wires 90
within overtube 22 extend from the distal region of the apparatus,
through overtube 22, and to handle 91. Within handle 91, the
tension wires are slidably coupled to distal pulleys 87, which in
turn are slidably coupled to proximal pulley 89. Proximal pulley 89
is coupled to and translates with slide block 92, that is keyed to
travel along track 93 disposed within housing 94. Plunger 95 is
mounted pivotally to slide block 92 at the proximal end and
slidably disposed within plunger housing at a distal end.
[0115] Plunger housing 96 is mounted pivotally to actuator 27,
illustratively hand grip 97. To bias hand grip 97 against actuation
absent an externally applied force, compression spring 98 is
provided concentrically disposed about plunger 95. Compression
spring 98 maintains tension wires 90 in constant tension when the
tensioning mechanism is actuated to impose a clamping load.
Advantageously, if adjacent nestable elements shift slightly when
overtube 22 is shape-locked, the proximal bias of compression
spring 98 immediately advances slide block 92 in the proximal
direction to maintain a relatively constant tension load within
tension wires 90, thereby reducing the risk of reconfiguration of
the overtube back to the flexible state that otherwise may occur
absent compression spring 98.
[0116] Hand grip 27 also includes pawl 99, which is disposed to
engage teeth 100 on ratchet bar 101 to prevent distally-directed
motion of slide block 92. Ratchet bar 101 is pivotally mounted in
housing 94 with a spring (not shown) that, with the aid of
compression spring 98, biases pawl 99 against teeth 100 of ratchet
bar 101, to provide a one-way ratchet effect when hand grip 97 is
squeezed.
[0117] In operation, squeezing hand grip 97 causes pawl 99 to
capture the next proximal-most tooth 100. This movement also
provides a compressive force to compression spring 98 that is
transmitted to slide block 92. The proximally-directed component of
the compressive force causes slide block 92 to translate along
track 93, proximally retracting tension wires 90 so that a clamping
load is imposed on the nestable elements within overtube 22.
Further actuation of hand grip 97 causes overtube 22 to stiffen
progressively in the manner previously described.
[0118] Advantageously, proximal-most tooth 100a is disposed on
ratchet bar 101 at a predetermined proximal location that permits a
single actuation of hand grip 97 to completely transition overtube
22 from its flexible state to its shape-fixed state. Furthermore,
as pawl 99 advances hand grip 97 closer to housing 94, the
mechanical advantage of the actuation of the hand grip increases.
More specifically, as hand grip 97 becomes increasingly horizontal,
the proximally-directed component of the force transmitted by
compression spring 98 increases in magnitude. Accordingly, more
force is transmitted to increase tension within tension wires 90,
and thus increase the clamping load applied to rigidize overtube
22.
[0119] When it is desired to transition overtube 22 into the
flexible state, pawl 99 is released from engagement with teeth 100
by rotating ratchet bar 101 in the proximal direction. The release
of the compressive load applied to compression spring 98 causes
hand grip 97 to rotate in the distal direction and slide block 92
to retract in the distal direction. This sufficiently relaxes
tension wires 90 so that the tension wires retain little to no
tension, thereby permitting overtube 22 to assume its most flexible
state.
[0120] Referring now to FIGS. 12A-12D, alternative embodiments of
fail-safe tensioning mechanisms are described, in which the
plurality of pulleys of the previous embodiment is replaced by a
single pulley manifold. In FIG. 12A, a first embodiment of a pulley
manifold is described. Pulley manifold 110 includes body 111 having
central bore 112 that accommodates colonoscope 10, first and second
grooves 113a and 113b that each accept a tension wire, and are
milled or molded into lateral surface 114 of body 111, and yoke 115
that is configured to couple pulley manifold 110 to an actuator
(not shown).
[0121] First groove 113 includes a curved track that terminates at
first distal ends 116a disposed diametrically opposite each other
at distal surface 117. Second groove 113b also comprises a curved
track that crosses first groove 113a at intersection 118, and
terminates at second distal ends 116b. Second distal ends 116b are
disposed at distal surface 117 diametrically opposite each other
and preferably 45.degree. from first distal ends 116a. Similar to
distal pulleys 87 of FIG. 10B, each groove accepts a tension wire
that extends through diametrically disposed tension wire lumens
within overtube 22. To reduce friction between tension wires 90a
and 90b at intersection 118, first groove 113a may have a greater
depth than that of second groove 113b, or vice versa. To prevent
tension wires 90 from disengaging from grooves 113, a sleeve (not
shown) may be disposed around pulley manifold 110.
[0122] If tension wires 90 comprise two separate lengths of wires,
the risk of reconfiguration of overtube 22 is reduced if one of the
wires breaks since the tension within the overtube, as defined by
the unbroken tension wire, is symmetrically balanced. If the
remaining tension wire breaks, the overtube relaxes into the
flexible state. If tension wires 90 comprise a single length of
wire, the overtube immediately relaxes into the flexible state if
the single wire breaks. Accordingly, pulley manifold 110 provides
overtube 22 with a fail-safe mode that reduces the risk of
reconfiguration of the overtube in the event of tensioning
mechanism failure.
[0123] FIG. 12B depicts pulley manifold 110, in which the yoke is
replaced with third groove 120. Third groove 120 is milled or
molded into lateral surface 114, and accepts an additional tension
wire 121 that may be coupled to actuator 27 (see FIG. 2). When a
proximally directed force F is applied to tension wire 121, the
force imposes tension to tension wires 90. Third groove 120
includes a curved track that terminates at third distal ends 122,
which preferably are diametrically disposed opposite each other at
proximal surface 123 of pulley manifold 110.
[0124] With respect to FIGS. 12A and 12B, an alternative embodiment
of a pulley manifold is described. Rather than having grooves
disposed on a lateral surface of the pulley manifold, pulley
manifold 130 incorporates first and second grooves 131a and 131b
that terminate at tension wire bores 132 disposed through body 133.
Preferably, tension wire bores 132 are equidistantly and
circumferentially disposed on proximal surface 136. Pulley manifold
130 also incorporates central bore 134 that accommodates
colonoscope 10, and yoke 135 that couples pulley manifold 130 to
actuator 27 (see FIG. 2).
[0125] In FIG. 12C, first and second grooves 131a and 131b are
milled or molded in overlapping fashion. To reduce friction between
tension wires disposed within the overlapping portion of the
grooves, first groove 131a may have a depth greater than that of
second groove 131b, or vice versa. In FIG. 12D, the first and
second grooves do not overlap, first groove 131a having a smaller
radius of curvature than that of second groove 131b.
[0126] Applicants also contemplate that either the first or second
groove of the pulley manifolds of FIGS. 12A-12D may be eliminated
so that a proximal force F applied thereto would impose a
symmetrical compressive clamping force to overtube 22 through a
single length of tension wire 90 that extends through diametrically
disposed tension wire lumens. Accordingly, when tension wire 90 or
121 breaks, or yoke 115 fails, the overtube relaxes back into its
flexible state, thereby reducing the risk of undesired
reconfiguration of the overtube.
[0127] Referring now to FIGS. 13A and 13B, handle 21 is described
employing pulley manifold 110 of FIG. 12B. Tension wires 90 within
overtube 22, skin 45, liner (not shown for illustrative purposes)
and lumen 25 extend from distal region 23 (see FIG. 2), through
overtube 22, and to handle 140, which preferably measures less than
or equal to 5 inches, similar to the other handle embodiments
described herein. Within handle 140, tension wires are slidably
coupled to pulley manifold 110, which rides within cylindrical
extension 141 and cylinder 142. Cylindrical extension 141 may be
integrally manufactured with housing 143, and is configured to be
inserted into a patient's rectum. Concentric with cylindrical
extension 141, cylinder 142 defines the proximal portion of lumen
25 disposed within handle 140.
[0128] Via additional tension wire 121, pulley manifold 110 is
coupled to slide block 92, which is keyed to translate in track 93.
As in handle 91 of FIG. 11, plunger 95 is coupled pivotally to
slide block 92 at a proximal end, and slidably disposed within
plunger housing 96 at a distal end. Concentrically disposed about
plunger 95, compression spring 98 biases hand grip 97 from being
actuated absent an externally applied force. As in FIG. 11,
compression spring 98 maintains the level of tension within tension
wires 90 if adjacent nestable elements shift slightly when overtube
22 is in the rigid state, thereby reducing the risk of
reconfiguration of the overtube back to the flexible state.
[0129] Hand grip 97 also includes pawl 99, which is configured to
engage tooth 144 of ratchet bar 145 to prevent distally-directed
motion of slide-block 92. Tooth 144 is disposed on ratchet bar 145
at a predetermined proximal location that permits a single
actuation of hand grip 97 to completely transition overtube 22 from
its flexible state to its shape-fixed state. Ratchet bar 145 is
mounted pivotally in housing 143 with a spring (not shown) that,
with the aid of compression spring 98, biases pawl 99 against tooth
144. To release tension from tension wires 90, pawl 99 may be
released from engagement with tooth 144 by rotating ratchet bar 145
in the proximal direction. This sufficiently relaxes tension wires
90 so that the tension wires retain little to no tension, thereby
permitting overtube 22 to assume its most flexible state.
[0130] Handle 140 also has shield 146 coupled to a distal end
thereof. Shield 146 prevents handle 140 proximal thereto from
inadvertently being inserted into the patient's rectum. Handle 140
also incorporates indicator 147 (FIG. 13B) that provides a
clinician with information about the rigidity of overtube 22.
Indicator 147 comprises slot 148 disposed through a wall of housing
143, pointer 149 disposed through slot 148, and scale 150 disposed
on an external surface of housing 143 adjacent to slot 148. Pointer
149 is coupled to translation of proximal manifold 110 so that it
translates with the manifold. Scale 150 incorporates color
gradations, or indicia (not shown) to indicate the rigidity of
overtube 22. Of course, it will be obvious to one of ordinary skill
in the art that pointer 149 may be coupled to any structure within
handle 140 that moves when actuator 27 is actuated, e.g., slide
block 92 or pawl 99. Alternatively, handle 140 may include a force
sensor coupled between the distal end of track 93 and slide block
92.
[0131] It also will be evident to one of ordinary skill in the art
that any of the handle embodiments described herein also may
incorporate cylindrical extension 141 for insertion into a
patient's rectum, one tooth 144 on a ratchet bar to transition the
overtube from a flexible state to a rigid state with a single
actuation of actuator 27, shield 146 to prevent insertion of the
handle into the patient's rectum, indicator 147 to provide a
clinician with information about the rigidity of the overtube, and
combinations thereof.
[0132] Referring now to FIGS. 14A-14C, yet another alternative
embodiment of a tensioning mechanism suitable for use with the
apparatus of the present invention is described. Handle 160 is
adapted to reconfigure the overtube between its flexible and rigid
states with successive actuations of actuator 27. Handle 160 has
housing 161 containing plurality of fixed pillars 162 that are
circumferentially and azimuthally disposed around inner cylindrical
chamber 163 of housing 161. Each fixed pillar 162 has beveled
concavity 164 disposed on a proximal end adjacent beveled arm 165.
Channel 166 is disposed between adjacent pillars 162.
[0133] Handle 160 also incorporates compression spring 167
proximally disposed to bias rotatably mounted manifold 168 against
plurality of pillars 162. Manifold 168 incorporates plurality of
distally projecting posts 169 having beveled distal ends 170 with
inclination angles that match those of beveled concavities 164 and
beveled arms 165. Accordingly, when beveled distal ends 170 are
forcefully engaged with beveled concavities 164, a component of the
force imparted by posts 169 causes manifold 168 to rotate, absent
the presence of beveled arm 165. Likewise, when the beveled distal
ends are engaged with beveled arms 165, a component of the force
imparted by posts 169 rotates the manifold so that pillars 162 are
disposed at the proximal ends of channels 166.
[0134] Also attached to manifold 168 is tension spring 171, that in
turn preferably is coupled to one of the pulley systems of FIGS.
10A-10C or 12A-12D. Tension spring 171 maintains tension wires 90
in constant tension if nestable elements disposed within the
overtube slightly shift when the overtube is rigidized.
Accordingly, this reduces the risk of reconfiguration of the
overtube into the flexible state that otherwise would occur absent
tension spring 171.
[0135] Handle 160 further comprises translatable cylindrical collar
172 having proximally projecting teeth 173. Each tooth has an
inclination angle that substantially is equivalent to that of
beveled distal ends 170 of manifold 168. Accordingly, when teeth
173 are engaged forcefully with beveled distal ends 170, a
component of the force imparted by the teeth rotates the manifold.
Also coupled to collar 172 is actuator 27, illustratively
translatable hand grip 174, that may be squeezed against stationary
hand grip 175 to retract collar 172 in the proximal direction to
contact beveled distal ends 170 of manifold 168.
[0136] FIG. 14B depicts the configuration of handle 160 when an
overtube coupled thereto is in the rigidized state. Beveled distal
ends 170 of manifold 168 are engaged within concavities 164 of
pillars 162. When it is desired to reconfigure the overtube into
its flexible state, translatable hand grip 174 is squeezed against
stationary hand grip 175. This action translates collar 172 in the
proximal direction. When teeth 173 engage beveled distal ends 170,
continual proximal advancement of translatable hand grip 174 causes
collar to push manifold 168 in the proximal direction against
compression spring 167. When beveled distal ends 170 clear beveled
arm 165, the forces imparted by teeth 173 to the beveled distal
ends rotate manifold 168 so that beveled distal ends 170 are
engaged to beveled arms 165, as shown in FIG. 14B.
[0137] Retraction of collar 172 disengages teeth 173 from manifold
168. The forces imparted by beveled arm 165 to the beveled distal
ends rotate manifold 168 until the beveled distal ends clear pillar
162. Thereafter, the bias of compression spring 167 advances
plurality of posts 169 into channels 166. FIG. 14C depicts this
configuration, in which the overtube is in its flexible state.
[0138] To reconfigure the overtube back into its rigid state,
translatable hand grip 174 again is squeezed against stationary
hand grip 175. This proximally advances collar 172 until teeth 173
contact beveled distal ends 170 of posts 169. Continual proximal
actuation of translatable hand grip 174 causes collar 172 to push
posts 169 out of channels 166. When beveled distal ends 170 clear
pillars 162, the forces imparted by teeth 173 to beveled distal
ends 170 rotate manifold 168. Distal retraction of collar 172
disengages teeth 173 from manifold 168, and the bias of compression
spring 167 advances manifold 168 until beveled distal ends 170
completely engage concavities 164.
[0139] Referring now to FIG. 15, still another alternative
embodiment of handle 21 suitable for use with the apparatus of the
present invention is described. Handle 180 comprises housing 181
containing lumen 25 of the overtube. Handle 180 further includes
piston 182 translatably disposed within piston housing 183, which
is coupled in pneumatic communication via port 184 and tube 185
with a pressure source (not shown). Attached to piston shaft 186 is
pulley 187 around which proximal tension wire 188 is disposed.
Proximal tension wire 188 is affixed to housing 181 at its proximal
end 189 and to tension spring 190 at its distal end. Preferably,
tension spring 190 distally is coupled to one of the pulley systems
of FIGS. 10A-10C or 12A-12D. Similar to tension spring 171 of FIGS.
14A-14C and compression springs 98 of FIGS. 11 and 13, tension
spring 190 maintains the tension wires in constant tension when the
overtube is in the shape-locked state. This reduces the risk of
reconfiguration of the overtube to its flexible state if nestable
elements disposed therein slightly shift relative to adjacent
nestable elements.
[0140] To stiffen the overtube, the pressure source may be actuated
to infuse piston housing 183 with pressurized air that proximally
advances piston 182. This in turn advances pulley 187 in the
proximal direction, so that tension is applied to proximal tension
wire 188. That tension is transmitted through tension spring 190 to
tension wires disposed within the overtube, thereby imposing a
compressive clamping load to adjacent nestable elements disposed
within the overtube. To transition the shape-locked overtube into
the flexible state, the pressure source may be actuated to remove
air from piston housing 183. This retracts piston 182 and pulley
183 in the distal direction, thereby releasing the compressive
clamping load applied to the overtube.
[0141] Pursuant to another aspect of the present invention, tension
spring 190 may be replaced with a damper per se known in the art.
In addition to the advantages provided by the tension spring, the
damper allows tension within proximal tension wire 188, and thus
tension wires disposed within the overtube, to be slowly released.
Applicants contemplate that a damper may replace any of the
compression and tension springs described herein.
[0142] Referring now to FIG. 16, apparatus 20 may be provided with
a tensioning mechanism that is selectively operable to transition
overtube 22 between the flexible and rigid states substantially
without proximal movement of distal region 23 (see FIG. 2). In FIG.
16, tension wire 196 and lumen 25 extend from distal region 23,
through overtube 22, and to handle 195. Within handle 195, tension
wire 196 is slidably coupled to pulley manifold 197 that is rigidly
or rotatably affixed to distal end 198 of the handle. Pulley
manifold 197 preferably includes orthogonally disposed first and
second channels 199a and 199b. While FIG. 16 depicts only one
tension wire, it should be understood that a second tension wire
preferably is disposed through second channel 199b and nestable
elements 30.
[0143] Similar to the tensioning mechanisms of FIGS. 12A-12D and
13, the present tensioning mechanism also provides overtube 22 with
a fail-safe mode. If the tension wires disposed through channels
199 comprise two independent wires, the load within overtube 22
remains symmetrically distributed when one of the wires breaks.
Thus, the risk of reconfiguration of overtube 22 is reduced. If
these tension wires comprise a single length of wire, overtube 22
will relax into the flexible state if the single length of wire
breaks.
[0144] Between pulley 197 and nestable elements 30, tension wire
196 also extends through collar 200, which has distal surface 201
that is contoured to mate with proximal surface 32 of the
proximal-most nestable element 30. Collar 200 is disposed to
translate within housing 202 so that distal surface 201 engages
proximal surface 32 of nestable element 30 when collar 220 is
advanced in the distal-direction.
[0145] Collar 200 pivotally is connected to plunger 95, which is
slidably disposed within plunger housing 96. Plunger housing 96 in
turn is mounted pivotally to actuator 27, illustratively hand grip
97. To bias hand grip 97 against actuation absent an externally
applied force, and to maintain constant tension within tension wire
196 when overtube 22 is rigidized, compression spring 98 is
provided concentrically disposed about plunger 95.
[0146] Hand grip 97 also includes pawl 99, which is disposed to
engage teeth 100 on ratchet bar 101 to prevent proximally-directed
motion of collar 200. Ratchet bar 101 pivotally is mounted in
housing 202 with a spring (not shown) that, with the aid of
compression spring 98, biases pawl 99 against teeth 100 of ratchet
bar 101. Handle 195 also may incorporate annular extension 203 that
is disposed surrounding collar 200 and that may be inserted into a
patient's rectum.
[0147] Similar in operation to handle 91 of FIG. 11, when hand grip
97 is squeezed, pawl 99 engages the next distal-most tooth 100.
This action also transmits force through compression spring 98,
which pushes collar 200 into engagement with the proximal-most
nestable element. Continual actuation of hand grip 97 causes collar
200 to exert an increasing compressive clamping load to nestable
elements 30, which causes overtube 22 to stiffen into its
shape-locked state.
[0148] Advantageously, this configuration permits overtube 22 to
reconfigure between the flexible and rigid states without
substantial proximal movement of the distal end of the overtube. In
previous embodiments, nestable elements 30, are advanced in the
proximal direction when overtube 22 is rigidized, and due to
compression of adjacent nestable elements, overtube 22 shortens in
length. In contrast, when the present embodiment advances the
nestable elements in the distal direction, overtube 22 maintains
its length despite compression of adjacent nestable elements since
the length of the overtube substantially is limited by the length
of tension wire 196. This provides greater accuracy when using the
apparatus of the present invention, and is particularly useful in
delicate procedures.
[0149] It will be apparent to one of ordinary skill in the art
that, similar to the tensioning mechanism described in reference to
FIG. 13, ratchet bar 101 may be provided with only one tooth.
Alternatively, with minor modifications that will be evident to one
of ordinary skill in the art, the tensioning system of FIGS.
14A-14C may be coupled to collar 200 to transition overtube 22
between the flexible and rigid states with successive actuations of
actuator 27, or the piston mechanism described in reference to FIG.
15 may be coupled to collar 200 to drive translation thereof. More
specifically, rather than being pivotally coupled to plunger 95,
collar 200 instead may be fixedly coupled to a piston disposed to
provide motion along the longitudinal axis of collar 200.
Furthermore, second channel 199b may be eliminated from pulley
manifold 197 so that a single tension wire may translatably extend
through first channel 199a and diametrically disposed tension wire
bores disposed within collar 200 and nestable elements 30. When the
single tension wire breaks, the overtube relaxes into the flexible
state immediately, thereby providing a fail-safe mode that reduces
the risk of undesired reconfiguration of the overtube.
[0150] With respect to FIGS. 17A and 17B, an alternative structure
is described to facilitate movement of a colonoscope within lumen
25 of overtube 22. In particular, instead of using inner lining 43
as depicted in FIG. 4, some or all of nestable elements 30 may
include roller bearings 205 that are received in insets 206 formed
in nestable elements 30. Bearings 205 may be disposed on ring 207
to facilitate assembly of the device.
[0151] FIGS. 18A and 18B depict a further alternative embodiment,
in which lubricious flexible rails 208 are disposed within bore 33
of nestable elements 30. Rails 208 span the length of lumen 25, and
reduce contact between the colonoscope and the interior of the
overtube, thereby facilitating movement of the colonoscope through
overtube 22.
[0152] In FIGS. 19 and 20, still further alternative structures are
described to facilitate movement of a colonoscope within lumen 25
of overtube 22. More specifically, rather than using liner 43 as
shown in FIG. 4, some or all of nestable elements 30 may
incorporate hydrophilically-coated polymeric layer 209, which may
be disposed surrounding distal portion 210 of bore 33.
[0153] Alternatively, as described in FIGS. 20A and 20B, overtube
22 may comprise multiplicity of frustoconical elements 215 that,
when nested, provide a smooth inner lumen to accommodate
colonoscope 10 without the need for a separate liner. Each
frustoconical element 215 includes central bore 216, and at least
two or more tension wire bores 217. Central bore 216 is defined by
cylindrical distal inner surface 218 that has a substantially
constant diameter, and proximal inner surface 219 that is
continuous with distal inner surface 218.
[0154] Proximal inner surface 219 is slightly curved in a radially
outward direction so that, when tension wires 36 are relaxed,
proximal inner surface 219 can rotate relative to external surface
220 of an adjacent element. External surface 220 of each
frustoconical element may be straight or contoured to conform to
the shape of proximal inner surface 219, and tapers each element so
that distal end 221 is smaller in outer diameter than proximal end
222. When frustoconical elements 215 are nested together, distal
inner surface 218 of each frustoconical element is disposed
adjacent to the distal inner surface of an adjoining frustoconical
element.
[0155] Advantageously, the present configuration provides lumen 25
with a substantially continuous profile. This permits smooth
advancement of colonoscope 10 therethrough, and thereby eliminates
the need to dispose a separate liner within lumen 25. To provide a
lubricious passageway to further facilitate advancement of the
colonoscope, each frustoconical element optionally may incorporate
an integral hydrophilic polymeric lining as described with respect
to the preceding embodiment of FIG. 19, or a thin, flexible lining
having a hydrophilic coating may be disposed through lumen 25.
[0156] In FIGS. 21A-21C, yet another alternative structure is
described, in which distal surface 31 of each nestable element is
macroscopically textured to increase the friction between adjacent
nestable elements 30 when a compressive clamping load is applied to
overtube 22. Illustratively, each element 30 may incorporate
multiplicity of divots 225 disposed on distal surface 31, and teeth
226 that are disposed on proximal surface 32 adjacent proximal edge
227. Teeth 226 are contoured to mate with the multiplicity of
divots disposed on an adjacent element. Accordingly, when overtube
22 is tensioned, retraction of tension wires 36 (see FIG. 3)
applies a clamping load to elements 30 that causes teeth 226 of
each element to forcefully engage divots 225 of an adjacent
element. This reduces the risk of relative angular movement between
adjacent nestable elements 30 when overtube 22 is shape-locked,
which in turn reduces the risk of undesired reconfiguration of the
overtube.
[0157] To prevent divots 225 and teeth 226 from engaging, and thus
provide smooth angular movement between adjacent elements 30, when
overtube 22 is in the flexible state, one or more leaf springs 228
may be molded integrally with proximal surface 32. Accordingly,
absent compressive clamping load applied by tension wires 36 to
stiffen overtube 22, leaf spring 228 of each element 30 coacts with
distal surface 31 of an adjacent element to prevent coaction of
proximal and distal surface 32 and 31, which prevents engagement of
teeth 226 with divots 225.
[0158] Alternatively, rather than having a leaf spring, nestable
elements 30 may be provided with one or more cantilever springs 229
that are cut from wall 34 and plastically bent into bore 33 of
nestable element 30. Similar to leaf springs 228, cantilever
springs 229 prevent coaction between distal and proximal surfaces
31 and 32 so that teeth 226 do not engage divots 225 absent a
compressive clamping load. Cantilever springs 229 may be aligned
with a longitudinal axis of nestable element 30, as shown in FIG.
21B, and/or aligned with a circumference of nestable element 30, as
shown in FIG. 21C. Applicants also contemplate that teeth 226 may
be disposed on distal surface 31 and divots 225 may be disposed on
proximal surface 32. One of ordinary skill in the art will
recognize additional macroscopic textures that will increase
friction between distal and proximal surfaces of adjacent elements
30.
[0159] On the other hand, instead of providing leaf or cantilever
springs integral with nestable elements 30, thin, flexible disc 232
(FIG. 21D) may be disposed between adjacent nestable elements 30 to
prevent divots 225 (see FIGS. 21A-21C) and teeth 226 of the
adjacent elements from engaging, absent a compressive clamping
load. Each disc 232 incorporates central bore 233 that accommodates
a colonoscope, and is made from an elastomeric material. For
purposes of illustration, nestable elements 30 and discs 232 are
shown spaced-apart, but it should be understood that the elements
and discs are disposed so that distal surface 31 of one element 30
and proximal surface 32 of an adjacent element coacts with disc
232, which is disposed therebetween. It also should be understood
that each nestable element 30 also comprises tension wire bores,
which are not shown in FIGS. 21A-21D for illustrative purposes.
[0160] Pursuant to one aspect of the present invention, nestable
elements 30 also may incorporate band 231 that is disposed distally
adjacent to proximal edge 227. Band 231 increases the thickness of
the proximal portion of wall 34 to distribute the applied
compressive clamping load over a larger cross-sectional area, and
thereby reduce radially outward deflection of wall 34. This in turn
reduces longitudinal contraction of overtube 22. Band 231
preferably is made from a metal to provide greater structural
integrity to wall 34, but also may be integral therewith.
[0161] In accordance with another aspect of the present invention,
the diameter of lumen 25 preferably is configured to facilitate
simultaneous passage of more than one diagnostic or therapeutic
instrument therethrough. As shown in FIG. 22, lumen 25 may be
dimensioned to permit auxiliary devices AD, such as for aspiration,
biopsy, or additional lighting, to be advanced alongside
colonoscope 10. For example, if lumen 25 has a diameter of 13 mm
and colonoscope 10 has an outer diameter of 10 mm, auxiliary device
AD, such as a catheter, having a diameter of between 3 F to 9 F may
be advanced through the remaining space within lumen 25.
Advantageously, this permits auxiliary devices AD to be
successively placed within the patient's colon to perform
additional diagnostic or therapeutic procedures without the need to
remove colonoscope 10 and overtube 22 therefrom.
[0162] Referring to FIG. 23, an alternative embodiment of a distal
region suitable for use in the overtube of the present invention is
described. Distal region 235 is similar in construction to distal
region 23 of the embodiment of FIG. 4, but has flexible coil 236
embedded in only the proximal portion of elastomeric layer 237.
Atraumatic tip 238 at the distal end of distal region 235 may
further enhance the steerability of overtube 22 when the steerable
tip of the colonoscope is disposed therein.
[0163] FIGS. 24-28 illustrate additional configurations of
atraumatic tips suitable for causing "tenting" of the wall of the
hollow body organ. As used herein, tenting refers to the tendency
of the atraumatic tip to be deflected radially outward in the
vicinity of the tip of the overtube. This reduces the risk that the
wall of the organ will become pinched or caught between the
colonoscope and the entry to overtube 22 when the colonoscope is
retracted within the overtube.
[0164] FIG. 24A shows atraumatic tip 24 in the form of an
inflatable donut-shaped balloon 240 affixed to distal region 23 of
overtube 22. Inflation lumen 241 extends from the handle through
overtube 22 to provide fluid communication between balloon 240 and
an inflation source, such as a syringe (not shown). As illustrated
in FIG. 24B, when balloon 240 is inflated, the wall of the colon
radially deflects around balloon 240. Thus, when colonoscope 10 is
retracted into lumen 25, it is less likely that the wall of the
colon will be pinched or potentially dissected between overtube 22
and colonoscope 10. Furthermore, when inflated, balloon 240 closes
annular gap 242 disposed between the wall of overtube 22 and
colonoscope 10 to prevent bodily fluids and other matter from
entering lumen 25. Advantageously, balloon 240 provides a custom
fit around colonoscope 10.
[0165] FIG. 25 depicts a further alternative embodiment of
atraumatic tip 24, comprising soft membrane 245 covering shape
memory alloy petals 246. Petals 246 preferably comprise loops of
shape memory alloy wire, e.g., nickel titanium alloy, and extend
radially outward in the proximal direction near the distal opening
into lumen 25, so that the proximal end of membrane-covered petals
causes the "tenting" effect described hereinabove. The shape memory
alloy may be activated to adopt a pre-formed shape when exposed to
body temperature, and returned to a contracted state by flushing
overtube 22 with cold water or air. Alternatively, petals 246 may
be mechanically extended or retracted, or self-expanding.
[0166] FIG. 26 depicts a further alternative embodiment of
atraumatic tip 24. In the embodiment of FIG. 26, petals 250 covered
by soft elastomeric membrane 251 extend distally from distal region
23 to form funnel-shaped element 252. Atraumatic tip 24 provides a
similar tenting effect to that described for the preceding
embodiments.
[0167] FIGS. 27-28 provide further alternative configurations for
atraumatic tip 86 of the embodiment of FIG. 9. Tip 255 preferably
comprises a foam or soft elastomer, and may be affixed to distal
region 23 of overtube 22 using a suitable biocompatible adhesive.
FIG. 28 depicts an alternative shape for a foam or soft elastomer
bumper 260, which includes a proximally-extending flange 261. Of
course, one of ordinary skill in the art will recognize that other
configurations may be used in accordance with the principles of the
present invention to form atraumatic tips that cause localized
tenting of the colon wall, and these atraumatic tips may be used
with the passively-steerable distal regions of the embodiments of
FIGS. 4 and 23.
[0168] Referring now to FIGS. 29 and 30, alternative embodiments of
the overtube are described. Unlike overtube 22 of previously
described embodiments, in which a mechanical mechanism is actuated
to impart a clamping load to a multiplicity of nestable elements,
the embodiments of FIGS. 29 and 30 use alternative tensioning
mechanisms. In particular, the following embodiments comprise a
multiplicity of links to which a compressive clamping load may be
applied by contraction of shape memory materials.
[0169] In FIG. 29, a first alternative embodiment of the overtube
of the present invention is described. Overtube 270 includes
multiplicity of nestable elements 30 identical to those described
hereinabove. For purposes of illustration, nestable elements 30 are
shown spaced-apart, but it should be understood that elements 30
are disposed so that distal surface 31 of each element 30 coacts
with proximal surface 32 of an adjacent element. Each of nestable
elements 30 has central bore 33 to accommodate colonoscope 10, and
preferably two or more tension wire bores 35. When assembled as
shown in FIG. 29, nestable elements 30 are fastened with distal and
proximal surfaces 31 and 32 disposed in a coacting fashion by a
plurality of tension wires 271 that extend through tension wire
bores 35.
[0170] In contrast to overtube 22 of the previous embodiments,
tension wires 271 of the present overtube are made from a shape
memory material, e.g., nickel titanium alloy or an electroactive
polymer known in the art. Tension wires 271 are fixedly connected
to the distal end of overtube 270 at the distal ends and fixedly
connected to handle 21 at the proximal ends. When an electric
current is passed through tension wires 271, the wires contract in
length, imposing a compressive clamping load that clamps distal and
proximal surfaces 31 and 32 of nestable elements 30 together at the
current relative orientation, thereby fixing the shape of overtube
270. When application of electrical energy ceases, tension wires
271 re-elongates in length to provide for relative angular movement
between nestable elements 30. This in turn renders overtube 270
sufficiently flexible to negotiate a tortuous path through the
colon.
[0171] To provide overtube 270 with a fail-safe mode that reduces
the risk of undesired reconfiguration of the overtube in the event
of tensioning mechanism failure, diametrically disposed tension
wires 271 may be coupled in a serial circuit. Accordingly, when one
wire fails, the wire disposed diametrically opposite also
re-elongates to maintain a symmetrical clamping load within
overtube 270. Alternatively, all tension wires 271 may be
electrically coupled in a serial electrical circuit. Accordingly,
when one of the tension wires fails, overtube 270 returns to the
flexible state.
[0172] It should be understood that a tension spring (not shown) or
damper (not shown) that are similar to those described hereinabove
may be coupled between the proximal ends of tension wires 271 and
handle 21 (see FIG. 2). Inter alia, this maintains the tension
wires in constant tension when the overtube is in the shape-locked
state, thereby reducing the risk of reconfiguration of the overtube
to its flexible state if nestable elements disposed therein
slightly shift relative to adjacent nestable elements.
[0173] Alternatively, as described in FIG. 30, overtube 280 may
include multiplicity of nestable elements 281 that are similar to
those of the preceding embodiments. For purposes of illustration,
nestable elements 281 are shown spaced-apart, but it should be
understood that elements 281 are disposed so that distal surface
282 of each element 280 coacts with proximal surface 283 of an
adjacent element. Each of nestable elements 280 has central bore
284 to accommodate colonoscope 10.
[0174] When assembled as shown in FIG. 30, nestable elements 280
are fastened with distal and proximal surfaces 282 and 283 disposed
in coacting fashion by plurality of thin tension ribbons 285 that
are fixedly connected to nestable bridge elements 286. Tension
ribbons 285 are made from a shape memory material, e.g., nickel
titanium alloy or an electroactive polymer, and may be transitioned
from an equilibrium length to a contracted length when electrical
current is passed therethrough.
[0175] Nestable bridge elements 286 are disposed within overtube
280 between a predetermined number of nestable elements 281.
Similar to nestable elements 281, bridge elements 286 also comprise
central bore 287 that accommodates colonoscope 10, distal surface
288 that coacts with proximal surface 283 of a distally adjacent
nestable element, and proximal surface 289 that coacts with distal
surface 282 of a proximally adjacent nestable element 281. Each
bridge element also incorporates plurality of conductive elements
290 that are disposed azimuthally around central bore 287, and that
preferably couple tension ribbons 285 occupying the same angular
circumferential position within overtube 280 in a serial electrical
circuit.
[0176] When an electrical current is passed through tension ribbons
285, the ribbons contract in length, imposing a compressive load
that clamps distal and proximal surfaces of adjacent nestable
elements together at the current relative orientation, thereby
fixing the shape of overtube 280. When the energy source ceases
providing electricity, tension ribbons 285 re-elongates to the
equilibrium length to provide for relative angular movement between
the nestable elements. This in turn renders overtube 280
sufficiently flexible to negotiate a tortuous path through the
colon.
[0177] Pursuant to another aspect of the present invention, tension
ribbons 285 that are disposed at diametrically opposite
circumferential positions may be electrically coupled in a serial
circuit. Advantageously, this configuration provides overtube 280
with a fail-safe mode that reduces the risk of undesired
reconfiguration of the overtube in the event that one of the
electrical circuits established through the tension ribbons is
de-energized.
[0178] For example, overtube 280 of FIG. 30 maybe provided with
four sets of tension ribbons equidistantly disposed at 90.degree.
intervals. In the event that tension ribbons Ta de-energize, absent
electrical communication between tension ribbons Ta and tension
ribbons T, disposed diametrically opposite thereto, overtube 280
will spontaneously reconfigure into a new rigidized shape since the
tension within the overtube no longer will be symmetrically
balanced. The new shape of overtube 280 may not replicate the
tortuous path of the colon, and thus may cause substantial harm to
the patient.
[0179] Advantageously, the present invention may reduce the risk of
undesired reconfiguration preferably by electrically coupling
diametrically disposed tension ribbons in a serial circuit. When
tension ribbons Ta are de-energized, tension ribbons Tc also
de-energize to provide overtube 280 with symmetrical tension, as
provided by tension wires Tb and the tension wires disposed
diametrically opposite thereto (not shown). In this manner, the
overtube retains its desired rigidized shape in the event that the
tensioning mechanism malfunctions. To immediately return overtube
280 to its flexible state in the event that any of the tension
ribbons are de-energized, all tension ribbons 285 may be
electrically coupled in a serial circuit.
[0180] In an alternative embodiment, tension ribbons 285 may be
electrically coupled to rigidize select regions of the overtube
without rigidizing the remainder of the overtube. Illustratively,
this may be accomplished by coupling longitudinally adjacent
tension ribbons in a parallel circuit, and circumferentially
adjacent tension ribbons in a serial circuit.
[0181] Of course, it will be evident to one of ordinary skill in
the art that, while FIG. 30 depicts tension ribbons 285 to be
disposed within central bores 284 and 287, the tension ribbons also
may be disposed adjacent external lateral surfaces 292 of nestable
elements 281 and 286. Alternatively, the tension ribbons may extend
through tension ribbon bores (not shown) that may extend through
the distal and proximal surfaces of nestable elements 281, and be
affixed to nestable bridge elements 286.
[0182] With respect to FIGS. 31-37, alternative embodiments of
overtube 22 are described. Unlike overtube 22 of the
above-described embodiments, which comprised a multiplicity of
nestable elements that are clamped with a plurality of tension
wires or ribbons, the embodiments of FIGS. 31-37 use alternative
clamping mechanisms. In particular, the following embodiments
comprise a plurality of links that may be stiffened by the use of
compressive sleeves that compress individual links disposed along
the length of the overtube.
[0183] Referring now to FIGS. 31A-31C, a fourth alternative
embodiment of the overtube of the present invention is described.
Overtube 300 comprises a multiplicity of alternating spool links
301 and clamp links 302. Each spool link 301 and clamp link 302 has
a bore disposed therethrough to accommodate a standard colonoscope.
Spool link 301 comprises rounded edges 303 disposed on its distal
and proximal ends that are contoured to permit limited rotatable
engagement with one of two contoured grooves 304 disposed within
the bore of clamp link 302. Accordingly, clamp link 302 comprises a
greater outer diameter than spool link 301. Each clamp link 302
also has through-wall split 305 longitudinally disposed to permit a
reduction in the diameter of clamp link 302 when the clamp link is
compressed, as discussed hereinafter.
[0184] Still referring to FIGS. 31A-31C, a first embodiment of a
compressive sleeve comprising inflatable sleeve 310 having first
compressive portions 311 and second compressive portions 312.
Sleeve 310 is configured so that the inner diameters of second
compressive portions 312 are smaller than those of first
compressive portions 311 when sleeve 310 is inflated. Second
compressive portions 312 may be disposed to engage clamp links 302.
Thus, when inflatable sleeve 310 is inflated by an inflation source
(not shown) coupled to the handle, second compressive portions 312
compress against clamp links 202 to shape-fix overtube 300. In
FIGS. 31B and 31C, cross sectional views of first compressive
portions 311 and second compressive portions 312, respectively, are
shown when sleeve 310 is in its inflated state.
[0185] FIG. 32 illustrates an alternative embodiment of a
compressive sleeve that also comprises an inflatable bladder.
Unlike inflatable bladder 310 of FIGS. 31A-31C, spiral bladder 320
has a constant inner diameter. Spiral bladder 320 preferably is
helically disposed around the overtube. Accordingly, when bladder
320 is inflated, clamp links 302 are compressed onto spool links
301 to stiffen the overtube.
[0186] FIG. 33 depicts a further embodiment of a compressive sleeve
330, comprising discontinuous hoops 331 made of shape memory alloy
(e.g. nickel titanium alloy). Each hoop 331 includes gap 332, which
is spanned by spring 333. Each hoop 331 is electrically connected
to neighboring hoops 331 via insulated wires 334, so that a serial
electrical circuit is established. When hoops 331 are energized,
they undergo a phase transition that causes the hoops to contract
into a preformed shape that is diametrically smaller than the
non-energized shape. Since hoops 331 may be disposed about clamp
links 302, contraction of hoops 331 may be used to apply a clamping
load that compresses links 302 onto spool links 301 to stiffen the
overtube.
[0187] Springs 333 contribute to structural integrity when hoops
331 are in their non-energized state. To energize and thereby
contract hoops 331, an electrical current may be run through wires
334. To return hoops 331 to their non-contracted state and thereby
return the overtube to its flexible state, hoops 331 may be flushed
with cold water or air. Of course one of ordinary skill in the art
will recognize that hoops 331 also may be individually energized,
thus requiring a parallel circuit.
[0188] With respect to FIGS. 34A-34B, a still further alternative
embodiment of an overtube suitable for use in the present invention
is described. This embodiment comprises helical links 340 that are
formed from an integral strip 341 having regions of different
durometer, e.g., rigid material 342 and soft material 343. When
strip 341 is helically wound, helical links 340 are formed having
rigid portions 344 and soft portions 345. Rigid portions 344
provide structural integrity to the overtube, while soft portions
345 provide flexibility.
[0189] Helical links 340 are disposed within compressive sleeve
346, which includes first compressive portions 347 and second
compressive portions 348. Compressive sleeve 346 is identical in
structure and operation to that described in FIGS. 31A-31C, except
that second compressive portions 348 are aligned with, and apply a
clamping force to, rigid portions 344 of helical links 340. It will
of course be understood that an overtube in accordance with the
principles of the present invention could alternatively be formed
using helical links 340 and either of the clamping systems
described with respect to FIGS. 32 and 33.
[0190] Referring now to FIG. 35, another alternative embodiment of
an overtube is described, in which each Grecian link 350 includes
rigid first and second rims 351 and 352 disposed at longitudinally
opposing ends of flexible body 353. First rim 351 comprises
U-shaped arm 354 that defines channel 355 and opening 356. Second
rim 352 includes retroflexed arm 357, which when engaged to first
rim 351 of an adjacent, is disposed within channel 355 of U-shaped
arm 354 through opening 356 so that U-shaped arm 354 and
retroflexed arm 357 are engaged and overlap along the longitudinal
axis of the overtube.
[0191] Grecian links 350 are disposed within compressive sleeve
358, which includes first compressive portions 359 and second
compressive portions 360. Compressive sleeve 358 is identical in
structure and operation to that described in FIGS. 31A and 34A,
except that second compressive portions 360 are aligned with, and
apply a clamping force to, overlapping U-shaped arm 354 and
retroflexed arm 357 of the first and second rims. It will of course
be understood that an overtube in accordance with the principles of
the present invention couple alternatively be formed using Grecian
links 350 and either of the clamping systems described with respect
to FIGS. 32 and 33.
[0192] Referring now to FIG. 36, yet another alternative embodiment
of an overtube suitable for use in the present invention is
described. This embodiment comprises joint links 370 that include
ball 371 and socket 372 disposed at longitudinally opposing ends of
flexible body 373. When adjacent joint links 370 are engaged, ball
371 of one link is disposed within socket 372 of an adjacent link.
When the overtube is flexed, ball 371 coacts with socket 372 to
provide articulation of the overtube.
[0193] Joint links 370 are disposed within compressive sleeve 374,
which includes first compressive portions 375 and second
compressive portions 376. Compressive sleeve 374 is identical in
structure and operation to that described in FIGS. 31A, 34A and 35,
except that second compressive portions 376 are aligned with, and
apply a clamping force to, socket 372 within which ball 371 of an
adjacent link is disposed. It will of course be understood that an
overtube in accordance with the principles of the present invention
couple alternatively be formed using joint links 370 and either of
the clamping systems described with respect to FIGS. 32 and 33.
[0194] With respect to FIG. 37, a still further embodiment of an
overtube suitable for use in the apparatus of the present invention
is described. Overtube 380 comprises a heat-softenable polymer
layer 381, (e.g., Carbothane.RTM., a proprietary urethane-based
polymer available from Thermedics Polymer Products, Woburn, Mass.),
having wire 382 embedded within it. Wire 382 is coupled at the
handle to an energy source, so that by passing an electric current
through wire 382, sufficient resistive heating occurs to soften the
polymer layer 381, rendering it sufficiently flexible to negotiate
tortuous or unsupported anatomy. When electrical energy is not
supplied to wire 382, no resistive heating of the wire or the
polymer layer occurs, and the overtube instead cools and stiffens.
Wire 382 serves the dual purpose of providing kink resistance and
electric heating.
[0195] Still referring to FIG. 37, yet another alternative
embodiment of an overtube suitable for use in the present invention
comprises a soft elastomeric polymer layer 381 having a shape
memory alloy wire 382 embedded within layer 381. In this
embodiment, the shape memory alloy is selected to have a martensite
transition temperature above body temperature. When wire 382 is
heated to a temperature above body temperature, such as by passing
an electric current through it, the wire transitions into the
austenitic phase, and becomes stiffer, thereby shape locking the
overtube. When application of the electric current ceases, wire 382
cools back into the martensitic phase, and renders the overtube
flexible.
[0196] Referring now to FIGS. 38A-38C, an additional alternative
embodiment of an overtube suitable for use with the present
invention is described. Overtube 390 comprises elongate body 391
having central lumen 392 that accommodates colonoscope 10, and wire
lumens 393 that are defined by cylindrical wire lumen surfaces 394.
Within each wire lumen 393 is disposed wire 395 that extends the
length of the elongate body. Elongate body 391 is made from an
electroactive polymer known in the art that permits wire lumens 393
to vary in diameter responsive to electrical energization.
[0197] In particular, when an electrical current is passed through
elongate body 391, the diameter of each wire lumen 393 decreases so
that the wire lumens clamp around respective wires 395. Preferably,
both wires 395 and wire lumen surfaces 394 are textured to enhance
friction therebetween. This prevents further relative movement
between elongate body 391 and wires 395, and stiffens overtube 390.
When application of the electrical current ceases, wire lumens 393
increase in diameter to release wires 395 so that elongate body 391
may shift relative to wires 395. This in turn renders overtube 390
sufficiently flexible to negotiate a tortuous path through the
colon.
[0198] With respect to FIG. 39, yet another alternative embodiment
of the overtube is described. Overtube 400 incorporates
multiplicity of variable diameter links 401 disposed in overlapping
fashion surrounding multiplicity of rigid links 402, that provide
structural integrity to the overtube. Each link comprises a central
bore that defines lumen 25 of the overtube, and accommodates a
standard commercially available colonoscope. Variable diameter
links 401 preferably are manufactured from an electroactive polymer
or a shape memory alloy that contract in diameter when energized.
When variable diameter links 401 are electrically activated, the
variable diameter links tighten about rigid links 402 to transition
overtube 400 into a shape-locked state. When the variable diameter
links are electrically deactivated, the variable diameter links
sufficiently soften to return overtube 400 back to the flexible
state.
[0199] In a preferred embodiment, variable diameter links 401 and
rigid links 402 are formed from respective strips of material that
are helically wound in an overlapping fashion to form overtube 400.
Alternatively, each link may be individually formed and disposed in
an overlapping fashion.
[0200] In FIGS. 40A-40B, still another alternative embodiment of an
overtube suitable for use with the apparatus of the present
invention is illustrated schematically. Overtube 405 comprises
multiplicity of nestable hourglass elements 406 that preferably are
manufactured from an electroactive polymer or a shape memory alloy,
and each have bulbous distal and proximal portions 407 and 408
connected by neck 409. The diameter of neck 409 is smaller than the
maximum diameter of distal portion 407, which in turn is less than
the maximum diameter of proximal portion 408. The distal portion of
external surface 410 of each hourglass element 406 is contoured to
coact with the proximal portion of internal surface 411 of a
distally adjacent hourglass element. Accordingly, when a
multiplicity of hourglass elements are nested together to form
overtube 405, adjacent elements 406 may move relative to each other
when the overtube is in the flexible state.
[0201] To reduce friction between adjacent elements during relative
movement therebetween, proximal portions 408 include plurality of
slits 412 disposed contiguous with proximal edge 413. Slits 412
also facilitate contraction of proximal portion 408 of each element
around distal portion 407 of an adjacent element. Each hourglass
element 406 also has central bore 414 that accommodates colonoscope
10 (see FIG. 1).
[0202] When an electrical current is applied to multiplicity of
nestable hourglass elements 406, proximal portion 408 of each
element contracts in diameter around distal portion 407 of an
adjacent element. The compressive clamping force there applied
prevents relative movement between adjacent elements, thereby
shape-locking the overtube. When the nestable elements are
de-energized, proximal portions 408 sufficiently relax to permit
relative movement between adjacent nestable elements 406, and thus
permit overtube 405 to negotiate tortuous curves. For purposes of
illustration, it should be understood that the figures of the
present application may not depict an electrolytic medium,
electrodes, and insulated wires that are coupled to and facilitate
ionization, and thus contraction, of the electroactive polymers
described herein.
[0203] In accordance with another aspect of the present invention,
the overtube of the present invention may be provided with
disposable sheath 420 that may extend the length of overtube 22 and
be removed therefrom. Like the sheath described hereinabove with
respect to FIG. 4, sheath 420 of FIG. 41 also incorporates
distally-disposed atraumatic tip 421 and flexible, kink-resistant
coil 422 encapsulated in flexible layer 423. At its proximal end,
layer 423 joins or is integrally formed with lubricious liner 424
defining lumen 425, and flexible elastomeric skin 427. Liner 424
may incorporate optional flexible, kink-resistant coil 429, be made
of a thin, flexible material, and/or have a hydrophilic coating
thereon, similar to that described in reference to FIG. 4. Between
liner 424 and skin 427 is disposed annular chamber 428 within which
nestable elements 30 may be inserted. Sheath 420 is configured to
slide onto and be removed from a column of nestable elements 30 so
that the sheath may be discarded after a single use, while the
nestable elements and handle may be sterilized and reused.
Advantageously, substantial cost reductions may be realized.
[0204] Pursuant to another aspect of the present invention,
apparatus 20 further may be provided with a device to secure
colonoscope 10 to apparatus 20 prior to insertion of apparatus 20
and colonoscope 10 into the patient. FIG. 42 depicts strap 430 that
may be secured distally to handle 21 of apparatus 20 and proximally
to proximal portion 13 of colonoscope 10. Strap 430 preferably has
a length that prevents colonoscope 10 from decoupling from
apparatus 20 after the colonoscope is placed within the overtube.
Illustratively, strap 430 may be made of ductile wire or Velcro. If
strap 430 is made of ductile wire, the strap may be secured to
anchors 431 and 432 respectively disposed on handle 21 and
colonoscope 10. Anchor 432 may be integral with, or comprise an
adhesive suitable for application to colonoscope 10.
[0205] It will be obvious to one of ordinary skill in the art that,
while the above description has emphasized use of apparatus 20 in
the lower gastro-intestinal tract, and in particular, in performing
colonoscopy, the apparatus of the present invention also may be
used in the upper gastro-intestinal tract, and in laparoscopic
procedures as a variable rigidity trocar through which a steerable
laparoscopic endoscope or tool may be advanced. Apparatus 20 also
may be scaled down in size for use in endo-urological procedures.
For example, a miniaturized overtube may be advanced, along with a
steerable nephroscope, through a patient's ureter into a kidney for
access to the kidney's lower pole.
[0206] While preferred illustrative embodiments of the invention
are described above, it will be apparent to one skilled in the art
that various changes and modifications may be made therein without
departing from the invention. The appended claims are intended to
cover all such changes and modifications that fall within the true
spirit and scope of the invention.
* * * * *