Surgery – Endoscope – With protective sheath
Reexamination Certificate
2001-08-14
2004-05-11
Flanagan, Beverly M. (Department: 3739)
Surgery
Endoscope
With protective sheath
C600S920000
Reexamination Certificate
active
06733440
ABSTRACT:
TECHNICAL FIELD
The present invention is directed toward elongated imaging components and a method of making the components, and, more particularly, toward thin-walled, elastic sheaths for elongated imaging equipment and a method of making the same.
BACKGROUND OF THE INVENTION
The use of intrabody medical equipment, such as endoscopes, catheters, and the like, for diagnostic and therapeutic indications is rapidly expanding. To improve performance, the equipment has been optimized to best accomplish the selected purpose. As an example, endoscopes have been optimized and refined so as to provide upper endoscopes for the examination of the esophagus, stomach, and duodenum, colonoscopes for examining the colon, angioscopes for examining blood vessels, bronchoscopes for examining bronchi, laparoscopes for examining the peritoneal cavity, arthroscopes for examining joints and joint spaces, nasopharygoscopes for examining the nasal passage and pharynx, and intubation scopes for examination of a person's airway.
Optimization of intrabody medical equipment for such therapeutic and diagnostic procedures has resulted in sterile, inexpensive disposable components that are used alone or with non-disposable equipment. In the field of endoscopes, a conventional endoscope
10
, shown in
FIG. 1
, has an insertion tube
12
connected at its proximal end
14
to a handle or control body
16
. The insertion tube
12
is adapted to be inserted into a patient's body cavity to perform a selected therapeutic or diagnostic procedure. The insertion tube
12
contains an imaging system
18
having optical fibers or the like extending along the length of the insertion tube and terminating at a viewing window
19
in the insertion tube's distal end
20
. The imaging system
18
conveys an image from the viewing window
19
to an eyepiece
22
on the control body
16
or to a monitor (not shown), so the user can see into a selected body cavity during an endoscopic procedure. The endoscope
10
is described in greater detail in U.S. Pat. No. Re 34,110 and U.S. Pat. No. 4,646,722, which are incorporated herein by reference.
Disposable endoscopic sheath assemblies are used to cover the insertion tube
12
and protect it from contaminating a patient during use. Accordingly, the sheath assemblies alleviate the problem and cost of cleaning and sterilizing the insertion tube
12
between endoscopic procedures. The sheaths and endoscopes are usable in medical applications and also in industrial applications, such as visually inspecting difficult to reach areas in an environment that could damage or contaminate the endoscope. As an example, a sheathed endoscope can be used in an industrial area wherein the sheath protects the endoscope's insertion tube from adhesive or the like. As seen in
FIG. 1
, a conventional sheath assembly
24
, shown partially cut away for illustrative purposes, includes a sheath
26
that surrounds the endoscope's insertion tube
12
. The sheath assembly
24
may also contain one or more working channels
32
that extend along the insertion tube
12
and that are adapted to receive conventional endoscopic accessories therethrough without allowing the endoscope to contaminate the accessories during the endoscopic procedure. The sheath
26
has a distal end portion
21
that includes an endcap
34
having a transparent window
28
positioned to cover the viewing window
19
at the insertion tube's distal end
20
when the sheath assembly
24
is installed. The endcap
34
is sealably secured to the sheath's distal end portion
21
.
The sheath
26
and endcap
34
are commonly made from polymeric materials. The sheath
26
can be made from an inelastic polymer, such as PVC, acrylic, polycarbonate, polyethylene terephthalate or other thermoplastic polyesters, or can be made from an elastomeric material. Both materials presently have advantages and disadvantages.
Inelastic materials allow for thin-walled medical components that exhibit high strength and visible clarity. Using inelastic materials, the sheath
26
can be formed with a thin wall (measuring 0.003 inches or less) and a small diameter (such as 0.5 mm). Inelastic materials tend to be clearer than the elastic materials, and can thus provide better visibility with less distortion.
U.S. Pat. No. 5,443,781 to Saab teaches a method of forming an inelastic, disposable sheath with an integral, optically transparent window. Saab teaches forming the inelastic sheath by heating a sheet or film of optically transparent, inelastic, polymeric material until the material is malleable. As shown in
FIG. 2
, a mandrel
35
is thrust into the heated film
37
causing the film to stretch and to generally conform to the mandrel's shape. As a result, the heated film
37
is formed into an inelastic closed-end sheath
39
having sidewalls
36
, a flange or collar
38
at its open proximal end
40
, and a closed distal end
42
.
U.S. patent application Ser. No. 08/948,615, which is incorporated herein by reference, further teaches a method of forming an inelastic, endoscopic sheath for use on an insertion tube having a complex cross-sectional shape. The process applies a differential pressure to the outside and inside of the sheath during fabrication to conform the sheath to the shape of a mandrel. By selecting a mandrel with the proper complex shape, the end cap can closely receive the corresponding insertion tube.
Inelastic materials, however, have a number of disadvantages. Tight-fitting sheaths formed from inelastic materials may overly restrict bending when used with flexible insertion tubes. The insertion tube combined with the tight-fitting, inelastic sheath can only bend over a limited radius. If bent further, the sheath will either buckle, in the case of a thick-walled sheath, or the sheath material will become taught, in the case of a thin-walled sheath, preventing the insertion tube from bending further. Consequently, if the inelastic sheath is to be used in combination with a flexible endoscope, the sheath is typically either baggy or must contain bending features, such as accordion-like baffles or the like, as taught by Saab, to allow the insertion tube to sufficiently bend. Both baggy sheaths and these additional bending features add to the cross-sectional size of the sheath during use, which may result in additional pain or discomfort to the patient.
The sheath made from inelastic material cannot be stretched axially onto the insertion tube. As a result, the inelastic sheath does not provide axial tension in the sheath urging the transparent window of the sheath against and in alignment with the viewing window at the insertion tube's distal end. To retain the transparent window in position, additional features, such as connectors or helical coils, are typically built into the sheath. These features add to the complexity and cost of the sheath.
Conventional elastic sheaths have been developed and used with imaging devices such as endoscopes to overcome the drawbacks associated with the inelastic sheaths described above and to provide additional benefits. As an example, conventional elastic sheaths are designed so the sheath will easily bend with the insertion tube without substantially affecting the insertion tube's bending characteristics. The elastic sheath can also be stretched axially over the insertion tube to provide axial tension that retains the transparent window on the sheath against and in alignment with the viewing window at the insertion tube's distal end. The elastic sheath can be designed to closely or tightly cover the insertion tube while still being able to bend with the insertion tube, so the elastic sheath does not need additional bending features.
Elastic materials, however, also have some disadvantages. First, conventional elastic sheaths are manufactured by extruding elastomeric material, that is, by pushing or forcing the elastomeric material through a die to form the desired structure. The extruded elastic sheaths, however, have manufacturing limits that restric
Ailinger Robert
Martone Stephen
Dorsey & Whitney LLP
Flanagan Beverly M.
Vision - Sciences, Inc.
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