Patent Publication Number: US-9408524-B2

Title: Inflatable member for an endoscope sheath

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 11/373,453, filed on Mar. 9, 2006, and issued as U.S. Pat. No. 8,845,518 on Sep. 30, 2014, which is a divisional of U.S. patent application Ser. No. 10/094,406 filed on Mar. 8, 2002, now abandoned, which is a continuation-in-part of U.S. patent application Ser. No. 09/702,155, filed Oct. 30, 2000, and issued as U.S. Pat. No. 6,461,294 on Oct. 8, 2002. These applications and patents are herein incorporated in by reference, in their entirety, and for any purpose. 
    
    
     TECHNICAL FIELD 
     This invention relates generally to endoscopy, and more particularly to inflatable members attached to an endoscopic instrument. 
     BACKGROUND OF THE INVENTION 
     The use of endoscopes for diagnostic and therapeutic purposes is widespread. For example, there are upper endoscopes for examination of the esophagus, stomach and duodenum, colonoscopes for the examination of the colon, angioscopes for vascular examination, bronchoscopes for examining the bronchi, laparoscopes for examining the peritoneal cavity, and arthroscopes for the examination of joint spaces. The following discussion applies to all of these types of endoscopes. 
     An endoscope for examining the bronchial tract and conducting transbronchial biopsies is a good example of the usefulness of endoscopic technology. These devices, known as flexible bronchoscopes, are widely used in diagnosing pulmonary diseases since they are capable of reaching the more distal bronchi in the bronchial tract. To properly navigate and view a bronchial area, the bronchoscope is generally structured to contain a fiber optic bundle within the elongated probe section. Alternatively, the bronchoscope may utilize other means to view the bronchial area, such as a video device positioned within the bronchoscope. In addition to providing a direct viewing capability, flexible bronchoscopes generally possess a means to remove tissue samples, or other material from the bronchial tract for biopsy or culture purposes. Tissue samples for biopsy purposes may be collected using a biopsy forceps extending from the distal end of the bronchoscope or by brushing the suspect area to capture cellular material for subsequent microscopic examination. Another commonly used technique to collect cellular material is to wash, or lavage, the suspect area. When a lavage procedure is used, a solution is injected into the bronchial passage and subsequently withdrawn by suction through the distal end of the broncoscope to capture cellular material. Following withdrawal of the lavage fluid, the cellular material may be subjected to a cytological examination or culture. 
     One difficulty encountered in the use of endoscopes is continuously maintaining the endoscopic probe in a selected location within a body passage during the examination. Movement of the endoscopic probe while it is positioned within a body passage may occur for a number of reasons. For example, movement of the endoscope may occur due to an unintended bodily movement of the operator while the patient is undergoing the examination, or by an involuntary movement of the patient in response to the examination. Once the distal end of the endoscope has been dislodged from its intended location, it must be carefully repositioned before the examination may be resumed. Movement of the endoscope within a body passage is particularly pronounced during bronchoscopic examinations, since the patient must continue to breathe during the examination. Further, involuntary bronchospasmodic events within the bronchial passages may occur during the examination that will disrupt the location of the distal end of the bronchoscope. A significant additional difficulty resulting from unintended patient movement may arise when a biopsy procedure is conducted. Since a biopsy forceps or brush is generally used, an uncontrolled or unintended cutting of tissue in the passage due to patient movement may lead to hemoptysis. Moreover, since the biopsy forceps, or brush may reach and perforate the pleura, pneumothorax may also occur. 
     Still another difficulty encountered in the use of endoscopes for diagnostic purposes is the inability to sealably isolate a portion of the endoscope from the remainder of the body passage during an endoscopic examination. To facilitate internal viewing of a passage, for example, the fluid occupying the cavity is generally removed by means of a suction channel in the endoscope, which may be followed by the introduction of a gas through an additional channel in the endoscope to distend the internal space. Other endoscopic applications may require that a fluid be retained within the portion of the body passage that has been sealably isolated. For example, in transbronchial diagnostic procedures such as bronchoalveolar lavage, the bronchoscope is used to gently irrigate the air spaces in a distal air passage with a solution. Isolation of the solution to the region surrounding the distal end of the bronchoscope is required so that cellular samples removed during the lavage are sufficiently localized to be of diagnostic value. In particular, when collecting samples by lavage for use in the diagnosis of infectious pulmonary diseases, the sample must not be contaminated by bacterial or other agents transported to the distal end of the probe by the unrestrained movement of the solution through the passage. 
     Yet another difficulty encountered in the use of endoscopes occurs when the endoscope must be positioned at a relatively deep location within a body passage, so that a relatively long portion of the endoscope must be inserted into the patient. In such cases, the endoscope may be resistant to small, or incremental movements within the passage. Moreover, in certain cases, the endoscope length may develop sufficient resistance to further inward movement, so that the endoscope is prevented from extending to the intended location. Similar difficulties may also occur when the passage is relatively short, but includes relatively highly curved segments. Since the operator is generally limited to positional manipulations of exposed portions of the endoscope, considerable difficulty may be encountered in properly positioning the endoscope within body passages under these conditions. 
     Increasingly, endoscopes are used with disposable sheaths that are positioned over the insertion tube of the endoscope to avoid the communication of disease from one patient to another. An additional advantage of the disposable sheath is that it allows the device to be used at more frequent intervals, since the need for lengthy cleaning and sterilization procedures is largely eliminated. Generally, the sheath is comprised of a flexible, thin, resilient material, such as latex, or other similar materials, that fits over and surrounds the insertion tube of the endoscope so the insertion tube is completely isolated from contaminants. The sheath is generally further comprised of a viewing window at the distal end, and may include a plurality of internal channels, or lumens, through which biopsy samples or fluids may be either introduced or removed. Accordingly, an additional difficulty encountered in the use of endoscopes concerns the incorporation of positioning and passage-blocking means into the disposable outer sheath. 
     Consequently, there exists a need in the art for an apparatus that will continuously maintain an endoscopic probe in a selected position within a body passage during the examination. In addition, the apparatus must be able to sealably close the passage to either retain fluids within a closed space, or to prevent a fluid from reoccupying the space during an examination. Further, there exists a need in the art for an apparatus that permits an endoscopic probe to be properly positioned within a long body passage, and/or where the passage is highly curved. Finally, the apparatus must be compatible with disposable sheaths used with endoscopes. 
     SUMMARY OF THE INVENTION 
     The invention is directed towards apparatus and methods for attaching and forming enclosed inflatable members on an endoscope assembly with a disposable sheath. In one aspect, an apparatus in accordance with the invention includes a flexible and resilient cuff member that is positioned on the outer surface of the disposable sheath and seahibly and fixedly bonded to the sheath cover material at the cuff edges to form an annular space capable of inflation. The inflatable member formed thereby is inflated through a lumen internal to the sheath that has an opening into the interior annular space. In another aspect, the annular space may be divided into separate inflatable lobes. In still another aspect, the cuff member is a flexible and resilient enclosed member that is substantially toroidal in shape that is positioned on the outer surface of the sheath. In a further aspect, the inflatable member is formed from an excess length of sheath cover material disposed on the disposable sheath. A single reentrant fold of sheath material is formed with an edge that is sealably and fixedly bonded to the sheath cover material to form an annular space capable of inflation. In still another aspect, the excess length of cover material may be used to form members with dual reentrant folds that comprise inflatable members with single and dual inflatable lobes. In another aspect, at least a pair of enclosed inflatable members are spaced apart˜long the sheath of an endoscope insertion tube, which has a plurality of openings that project through the sheath to communicate a fluid to the space formed between the inflatable members. In still another aspect, at least a single enclosed inflatable member that has a first portion capable of a first expansion when inflated, and a second portion capable of a second expansion when inflated, is positioned on an endoscope sheath of an insertion tube to assist in the movement of the endoscope along a body passage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partial cross-sectional view of an endoscope assembly with an inflatable cuff according to an embodiment of the invention. 
         FIG. 2  is a cross-sectional view of an inflatable cuff according to another embodiment of the invention. 
         FIG. 3  is a cross-sectional view of an inflatable cuff according to still another embodiment of the invention. 
         FIG. 4  is a cross-sectional view of an inflatable cuff according to yet another embodiment of the invention. 
         FIG. 5  is a cross-sectional view of an inflatable cuff according to another alternative embodiment of the invention. 
         FIG. 6  is a cross-sectional view of an inflatable cuff according to still another alternative embodiment of the invention. 
         FIG. 7  is a cross-sectional view of an endoscope assembly with inflatable cuffs according to another embodiment of the invention. 
         FIG. 8  is a cross-sectional view of an endoscope assembly with inflatable cuffs according to still another embodiment of the invention. 
         FIG. 9  is a cross-sectional view of an endoscope assembly with inflatable cuffs according to still another embodiment of the invention. 
         FIG. 10  is a cross-sectional view of an endoscope assembly with inflatable cuffs according to still another embodiment of the invention. 
         FIG. 11  is an isometric view of an endoscope assembly with inflatable cuffs according to yet another embodiment of the invention. 
         FIG. 12  is a partial side view of an endoscope assembly with inflatable cuffs according to still yet another embodiment of the invention. 
         FIG. 13  is a partial side view of an endoscope assembly with inflatable cuffs according to still yet another embodiment of the invention. 
         FIG. 14  is a partial side view of an endoscope assembly with inflatable cuffs according to still yet another embodiment of the invention. 
         FIG. 15  is an end elevational view of the endoscope assembly of  FIG. 1  with the inflatable cuff in the inflated position. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is generally directed to inflatable members attached to an endoscope. Many of the specific details of certain embodiments of the invention are set forth in the following description and in  FIGS. 1 through 15  to provide a thorough understanding of such embodiments. One skilled in the art will understand, however, that the present invention may have additional embodiments, or that the present invention may be practiced without several of the details described in the following description. 
     In the drawings, like reference numbers identify similar elements or steps. Further, it is understood that the inflatable members depicted in  FIGS. 1 through 14  may assume a variety of sizes and shapes that depend on the amount of internal pressurization and/or the internal shape of a body cavity. Accordingly, for clarity of illustration, and to properly illustrate internal features of the various embodiments illustrated in  FIGS. 1 through 14 , the embodiments are shown at a generally intermediate stage of inflation. 
       FIG. 1  is a partial cross sectional view of an endoscope assembly  10  that includes a sheath  103  having an inflatable cuff  100  in accordance with an embodiment of the invention˜In this embodiment, the inflatable cuff  100  is circumferentially disposed about a body portion of the sheath  103 , the body portion being sized to at least partially encapsulate an insertion tube  101  of an endoscope of the type shown, for example, in  FIG. 11 . 
     When inflated, the cuff  100  may be symmetrically or asymmetrically disposed about the insertion tube  101 . For example,  FIG. 15  is an end elevational view of the endoscope assembly  10  with the inflatable cuff  100  shown in an inflated position  105 . As shown in  FIG. 15 , in this embodiment, the inflatable cuff  100  is symmetrically circumferentially disposed about the insertion tube  101 . In alternate embodiments, the inflatable cuff  100  may assume any desired shape, including, for example, an eccentrically-disposed circular shape  107  ( FIG. 15 ) that is not symmetrically disposed about the insertion tube  101 , or a non-circular, asymmetric shape  109  ( FIG. 15 ), or any other suitable shape. 
     The insertion tube  101  can have a variety of cross section shapes, such as circular, semicircular, etc., and is fabricated from a resilient material so that an insertion tube wall  102  may be flexed. The insertion tube  101  also has an internal space  104  that is structured to permit the illumination of tissue in internal passages, and to convey an image of the illuminated area from the distal end  110  of the endoscope to an external viewing device (not shown). 
     With reference still to  FIG. 1 , the endoscope sheath  103  has a transparent viewing window  118  located at the distal end  110  of the disposable sheath  103  to allow the image to be conveyed to the external viewing device. The window  118  may also be comprised of a lens capable of focusing an image on an image sensing device. The sheath  103  also has a plurality of internal lumens to accomplish specific tasks. For example, a lumen  124  may be provided to direct a flow of rinse water over the viewing window  118  in order to rinse vision-impairing matter from the window  118 . A lumen  122  that is open at the distal end  110  may be used to capture a biopsy sample taken from the surrounding tissue area by means of an elongated forceps, or brush (not shown). Alternatively, the lumen  122  may be used to transfer a solution into a body passage during a lavage procedure. Further, the lumen  122  may also be used to transfer a compressed gas into a body passage in order to distend the passage for better optical viewing or biopsy sampling. An additional lumen  120  that is in fluid communication With a pressurized fluid source (not shown) is used to inflate an inflatable endoscope cuff  100 , which will be described in greater detail below. The internal lumens  120 ,  122  and  124  are comprised of a resilient material to maintain flexibility of the sheath  103 . The sheath  103  is covered with a flexible, resilient cover material  130  such as latex, polyvinylchloride, or polyurethane. Alternatively, other equally suitable materials for the cover material  130  are KRATON®, available from the GLS Corporation of McHenry, Ill., and C-FLEX®, available from Consolidated Polymer Technologies, Inc. of Largo, Fla. 
     Still referring to  FIG. 1 , the inflatable endoscope cuff  100  is comprised of a circular member positioned on the outer surface of the sheath  103 . Although only a single inflatable cuff  100  is shown for clarity of illustration, it is understood that a plurality of cuffs  100  may be positioned along the length of the endoscope assembly  10 , and that the plurality of cuffs  100  may be positioned at varying relative distances. The inflatable cuff  100  may be located at any location along the working length of the endoscope assembly  10 , and forms a closed annular space  136  that is capable of inflation by a pressurized fluid. An opening  134  projects through the cover material  130  and through the wall of the lumen  120  to permit the pressurized fluid retained within the lumen  120  to enter the inflatable cuff  100 . To retain the cuff  100  on the surface of the sheath  103 , and to retain the pressurized fluid within the annular space  136 , the cuff  100  is sealably fastened to the surface of the sheath  103  at the cuff edges  138  with a suitable adhesive placed between the cuff edge  138  and the cover material  130 . An example of a suitable adhesive is cyanoacrylate, although other equivalent adhesives exist. Alternatively, the cuff edges  138  may be joined to the cover material  130  either by thermally fusing the cuff edges  138  to the cover material  130 , or by wrapping lengths of a retaining cord  131 , such as a surgical-type thread or other suitable material, over the cuff edge  138  and securely tying the ends to sealably fasten the cuff edges  138  to the cover material  130 , although other methods for attaching the cuff edges  138  to the cover material  130  may also be used. 
     The inflatable cuff  100  may be formed from latex, KRATON®, or C-FLEX®, although other suitable flexible and resilient materials may be used. For example, soft polyurethane may also be used. Preferably, the inflatable cuff  100  is formed from a flexible and resilient material with a thickness that ranges between 0.003 and 0.010 inches, with a durometer value of between approximately 30 and approximately 50. Alternatively, the cuff  100  may also be formed from a relatively inelastic material, so that it exhibits a relatively baggy shape when not inflated. 
     With reference now to  FIG. 2 , a partial cross sectional view of the endoscope assembly  10  with an alternative embodiment of an inflatable endoscope cuff  200  is shown. As shown therein, the inflatable endoscope cuff  200  is comprised of a resilient toroidally-shaped member  202  with an internal radius r and an external radius R. An opening  134  projects through the cover material  130  and through the wall of the lumen  140  to permit a pressurized fluid retained within the lumen interior space  112  to enter the inflatable member  202  through an opening  210  in the interior diameter of the member  202 . To sealably retain the pressurized fluid within the annular space  136 , the toroidally-shaped member  202  is sealably fastened to the surface of the sheath  103  at a location that is closely proximate to the opening  134 . Moreover, to positionally retain the member  202  in the desired location on the surface of the sheath  103 , it is preferable to join the interior diameter of the member  202  to the cover material  130  along a circumferential contact area  220  to ensure that the member  202  maintains its position on the endoscope assembly  10 . 
       FIG. 3  shows a partial cross sectional view of the endoscope assembly  10  with still another alternative embodiment of an inflatable endoscope cuff  300 . As shown in  FIG. 3 , the inflatable endoscope cuff  300  is comprised of a resilient circular member  302  positioned on the outer surface of the sheath  103 . In this embodiment, the length of the endoscope cuff  300  is sufficient to allow the formation of a pair of inflatable annular lobes  310  and  320  by attaching the circular member  302  to the cover material  130  at an approximate midpoint location  350  of the cuff  300 . The development of an inflatable endoscope member with dual lobes is regarded as particularly advantageous since the dual lobes are regarded as more effective in conforming to irregular internal surfaces in body passages. 
     Still referring to  FIG. 3 , the cuff  300  may be retained at the midpoint location  350 , and may be adhesively or thermally bonded to the cover material  130 . Alternatively, the cuff may be attached to the cover material  130  at the mid point location  350  by a length of thread  131  (as shown in  FIG. 1 ) wrapped around the cuff  300  that is securely knotted, although other methods may also be used. To retain the pressurized fluid within the inflatable annular lobes  310  and  320 , cuff edges  340  are seal ably joined to the cover material  130  using an adhesive or thermal bonding method as previously described. Openings  134   a  and  134   b  project through the cover material  130  and through the lumen wall  140  to permit the pressurized fluid retained in the lumen interior space  112  to enter the lobes  310  and  320  during inflation. 
     Turning now to  FIG. 4 , a partial cross sectional view of the endoscope assembly  10  with yet another alternative embodiment of an inflatable endoscope member  400  is shown. The endoscope assembly  10  according to this embodiment advantageously allows an inflatable member to be formed on the disposable sheath  103  without placing a separate circumferential member on the disposable sheath  103 . The inflatable member  400  is formed by providing an excess length of the cover material  130  on the sheath  103  that may be drawn along the surface of the sheath  103  by an edge fold  440  that extends circumferentially around the sheath  103  to form a reentrant fold  450  in the cover material  130  that also extends circumferentially around the disposable sheath I  03 . The edge fold  440  is subsequently sealably attached to the cover material  130  at a surface location  460  to form a closed annular space  410  that is capable of being inflated. The sealable attachment between the edge fold  440  and the cover material  130  may be comprised of an adhesive or thermal bond. Alternatively, the attachment may be comprised of a length of retaining cord  131  (e.g. surgical-type thread, as shown in  FIG. 1 ) that is wrapped over the edge fold  440  and securely knotted, although other methods may also be used. An opening  420  projects through the cover material  130  and is aligned with the opening  134  through the wall of the lumen  140  to permit the pressurized fluid retained within the lumen interior space  112  to enter the inflatable annular member  400  during inflation. The member  400  may be sealably fastened to the surface of the sheath  103  at a location  412  that is closely proximate to the opening  134  to ensure that the lumen opening  134  in the lumen wall  140  remains in substantial alignment with the opening  420  through the cover material  130 . 
       FIG. 5  shows a partial cross sectional view of the endoscope assembly  10  with still another alternative embodiment of an inflatable endoscope member  500 . As in the previous embodiment, the inflatable endoscope member  500  is advantageously formed from an excess length of the cover material  130  that is disposed on the sheath  103 . As shown in  FIG. 5 , the excess length of the cover material  130  is drawn in a first direction along the surface of the sheath  103  to form a first reentrant fold  530  with a first edge fold  570 . The first edge fold  570  is positioned approximately adjacent to the lumen opening  134 . A second reentrant fold  540  is then formed in the cover material  130  by drawing the excess length in a second direction that is opposite to the first, to form a second edge fold  580  that is also positioned approximately adjacent to the lumen opening  134 . When positioned approximately adjacent to the opening, the first edge fold  570  and the second edge fold  580  form an opening  590  into the inflatable enclosed annular space  510 . The first and second reentrant folds  530  and  540  are sealably attached to the lumen wall  140  at locations  550  and  560 , respectively, to ensure that the lumen opening  134  remains in substantial alignment with the opening  590 . Adhesive or thermal bonding may form the sealable attachment at locations  550  and  560 . As an alternative, a retaining cord  131  (e.g. surgical-type thread, as shown in  FIG. 1 ) may be inserted into the first reentrant fold  530  through the opening  520  and also inserted into the second reentrant fold  540  through the opening  525 , both lengths of retaining cord being wrapped around the circumference of the disposable sheath  103  and securely knotted to retain the inflatable member  500  in position on the sheath  103 , although other methods may also be used. 
     Turning now to  FIG. 6 , a partial cross sectional view of the endoscope assembly  10  with still another alternative embodiment of an inflatable endoscope member  600  is shown. The inflatable endoscope member  600  is similarly advantageously formed from an excess length of the cover material  130  that is disposed on the sheath  103 . Drawing the excess length of cover material  130  along the surface of the sheath  103  in a first direction to form a first reentrant fold  660  with a first edge fold  670  forms the inflatable member  600 . The first edge fold  670  is then positioned approximately adjacent to the opening  134   a . Drawing the excess length in a second direction that is opposite to the first direction then forms a second reentrant fold  665  with a second edge fold  675 . The second edge fold  675  is similarly positioned approximately adjacent to the opening  134   b . The inflatable member  600  is divided into a pair of inflatable lobes  610  and  620  by attaching the cover material comprising the member  600  to the lumen wall  140  at an approximate midpoint location  680 . The inflatable lobes  610  and  620  are inflated when pressurized fluid retained within the lumen interior space  112  enters the lobes through openings  134   a  and  134   b . The first and second reentrant folds  660  and  665  are sealably attached to the lumen wall  140  at locations  672  and  674  to ensure that the lumen openings  134   a  and  134   b  remain in substantial alignment with the lobe entrances  661  and  662 . As previously described, adhesive or thermal bonding may be used to form the sealable attachment at locations  672 ,  674  and  680 . As an alternative, a retaining cord  131  may be used to retain the position of the inflatable member on the sheath  103 , although other methods may also be used. 
       FIG. 7  is a cross-sectional view of an endoscope assembly  20  in accordance with yet another alternative embodiment of the invention. The assembly  20  is comprised of a pair of flexible, resilient inflatable cuffs  100   a  and  100   b  that are positioned on an outer surface of a disposable sheath  130 . The cuffs  100   a  and  100   b  are spaced apart along the length of the endoscope assembly  20  to define an inter-cuff length  750 . The sheath  130  encloses an interior space  705 , and may be positioned on an insertion tube  22  of an endoscope  21  of the type shown, for example, in  FIG. 11 . 
     Referring now to  FIG. 11 , an endoscope assembly  1000  according to an embodiment of the invention is shown. The endoscope assembly  1000  includes an endoscope  21  having an elongated insertion tube  22  that is comprised of a resilient material so that the tube may be flexed as it is positioned within an internal body passage  730 . The insertion tube  22  may be rigid, partially flexible or entirely flexible. The insertion tube  22  includes a distal portion  1002  that may be inserted into a body cavity of a patient (not shown) and a working end  1004 . The endoscope  21  includes a headpiece  1006  that remains external to the patient during an endoscopic procedure. In the embodiment shown in  FIG. 11 , the headpiece  1006  includes an eyepiece  1008  for viewing the scene through a viewing lens  1011  at the working end  1004  of the insertion tube  22 , a pair of bending control knobs  1012  for manipulating the position of the distal portion  1002  of the insertion tube  22 , and a pair of fluid control actuators  1014  for controlling the flow of fluids through tubes  1016  to (or from) the working end  1002 . Endoscopes  21  of the type generally shown in  FIG. 11  are described more fully, for example, in U.S. Pat. No. 5,931,833 to Silverstein, U.S. Pat. No. 5,483,951 to Frassica and Ailinger, and U.S. Pat. No. 4,714,075 to Krauter and Vivenzio, which patents are incorporated herein by reference. 
     Referring now to  FIGS. 7 and 11 , the sheath  130  shows a pair of inflatable cuffs  100   a  and  100   b . It is understood, however, that the sheath  130  may include a plurality of inflatable cuffs located along the length of the sheath  130 , and that the inflatable cuffs may be positioned along the length of the sheath  130  at varying inter-cuff lengths  750 . Further, the inflatable cuffs positioned along the length of the sheath  130  may be comprised of any of the inflatable cuffs previously shown in  FIGS. 2 through 6 . Moreover, any combination of the inflatable cuffs previously shown in  FIGS. 2 through 6  may be positioned along the length of the sheath  130 . 
     Referring again to  FIG. 7 , inflation lumens  702  and  704  are positioned within the interior space  705  of the endoscope  20 . The inflation lumens  702  and  704  are fluidly connected to a source of an inflation fluid (not shown) at lumen ends  740  and  742 . The lumens  702  and  704  fluidly communicate through openings  134   a  and  134   b  to allow the inflation fluid to be separately and selectively introduced into the annular spaces  136   a  and  136   b . In alternate embodiments, the pair of lumens  702  and  704  may be replaced with a single lumen to provide inflation fluid to more than a single inflatable cuff on the endoscope assembly  20 , so that the cuffs may be simultaneously inflated. Inflation of the cuffs  100   a  and  100   b  through the inflation lumens  702  and  704  thus allows an isolated body space  720  to be formed within the inter-cuff length  750  by sealably impressing the cuffs  100   a  and  100   b  against the body passage walls  732  of the body passage  730 , as shown, for example, in the lower portion of  FIG. 7 . 
     Lumens  706  and  708  may optionally be provided within the interior space  705  that communicate through openings  722  and  724  into the inter-cuff length  750 . The lumens  706  and  708  may be fluidly connected to a variety of fluid or suction sources at the opposing ends  744  and  746  in order to accomplish a variety of diagnostic tasks. For example, the lumen  706  may be fluidly connected to a source of a solution (not shown) to introduce the solution into the isolated body space  720 . The solution may then be subsequently withdrawn from the space  720  through another lumen  708  for analysis. Alternatively, the lumen  706  may be fluidly connected to a source of pressurized fluid (not shown) that may be used to distend the isolated body space  720  prior to the introduction of a solution into the space  720  by the lumen  708 . Although a pair of lumens  706  and  708  is shown in  FIG. 7 , it is understood that a single lumen, or more than two may optionally be used. 
     The endoscope assembly  20  advantageously allows the cuffs  100   a  and  100   b  to be separately and selectively inflated to permit the endoscope assembly  20  to sealably adjust to variations in thickness and elasticity of the body passage wall  732 . The endoscope assembly  20  further advantageously allows a portion of the body passage  730  to be fluidly isolated from the remaining portion of the passage so that lavage, or any of the diagnostic procedures previously described, may be conducted in the isolated body space  720 . 
       FIG. 8  is a cross-sectional view of an endoscope assembly  30  in accordance with still another alternative embodiment of the invention. The assembly  30  includes an inflatable first cuff  800   a  and a spaced apart inflatable second cuff  800   b , which are positioned on an outer surface of a disposable sheath  130 . The cuff  800   a  has a non-uniform wall thickness, and includes a forward portion  801   a , and a rear portion  802   a  that has a wall thickness that is less than the wall thickness of the forward portion  801   a . The cuff  800   b  similarly has a non-uniform wall thickness, and also includes a forward portion  801   b , and a rear portion  802   b  that has a wall thickness that is less than the wall thickness of the forward portion  801   b . The sheath  130  encloses an interior space  705 , and may be positioned on an insertion tube (not shown) that is comprised of a resilient material so that the tube may be flexed as it is positioned within an internal body passage  730 . Alternatively, the insertion tube may be rigid. 
     Inflation lumens  702  and  704  may be positioned within the interior space  705 , and may be fluidly connected to a source of an inflation fluid (not shown) at lumen ends  740  and  742 . The lumens  702  and  704  communicate through the sheath  130  at openings  134   a  and  134   b  to allow the inflation fluid to separately and selectively inflate the first cuff  800   a  and the second cuff  800   b . Alternatively, a single lumen  707  (shown in  FIG. 8  as a dotted line) may be used to provide inflation fluid to the first cuff  800   a  and the second cuff  800   b  so that the cuffs may be simultaneously inflated. 
     In operation, inflation of the first cuff  800   a  and the second cuff  800   b  through the inflation lumens  702  and  704  allows the cuffs  800   a  and  800   b  to be impressed against body passage wall  732  of a body passage  730 . Further, the non-uniform wall thicknesses of the first cuff  800   a  and the second cuff  800   b  permit greater expansion of the rear portions  802   a  and  802   b  of the cuffs  800   a  and  800   b  than is obtained in the respective front portions  801   a  and  801   b  of the cuffs  800   a  and  800   b  when the cuffs  800   a  and  800   b  are inflated. The respective rear portions  802   a  and  802   b  of cuffs  800   a  and  800   b  thus develop a longitudinally-directed biasing force that acts in a direction  810  when the inflated rear portions  802   a  and  802   b  contact the body passage wall  732 . In alternate embodiments, the thicknesses of the front and rear portions  801  and  802  can be reversed so that the biasing force acts in an opposite direction. 
     Referring now to  FIG. 9 , a cross-sectional view of the endoscope assembly is shown with the first cuff  800   a  at least partially inflated, with the rear portion  802   a  of the cuff  800   a  contacting a portion of the body passage wall  732 . In response to the biasing force developed by the rear portion  802   a , the assembly  30  is urged along the passage  730  in the direction  810  from a first position  910  to a second position  920 . 
       FIG. 10  is a cross sectional view of the assembly  30  with the first cuff  800   a  in a deflated condition, and the second cuff  800   b  at least partially inflated. The rear portion  802   b  of the cuff  800   b  contacts a portion of the body passage wall  732  and develops a biasing force that further urges the assembly  30  along the passage  730  in the direction  810  from the second position  920  to a third position  1010 . The second cuff  800   b  may then be deflated, and the process repeated. By alternately inflating and deflating the cuffs  800   a  and  800   b  in the manner described, the assembly  30  is able to incrementally move along the length of the body passage  730 . Alternatively, for certain body passages  730  and for certain endoscopic procedures, it may be desirable to keep one of the cuffs  800   a  or  800   b  inflated at all times (e.g. to provide an anchor), and to successively inflate and deflate the other of the cuffs to provide the desired longitudinal movement. It may also be desirable to keep one of the cuffs  800   a  or  800   b  deflated (or to eliminate one of the cuffs  800   a  or  800   b ) and to employ a single cuff to provide the desired longitudinal movement in the manner described. 
     Although the foregoing discussion has described the sequential alternating inflation and deflation of the first cuff  800   a  and the second cuff  800   b , in another embodiment, the cuffs  800   a  and  800   b  may be simultaneously inflated and deflated using the single lumen  707  to move the assembly  30  along the body passage  730 . Further, although the endoscope assembly  30  as depicted in  FIGS. 8 through 10  has a pair of cuffs  800   a  and  800   b , it is understood that the assembly  30  may be comprised of a plurality of inflatable cuffs located along the length of the assembly  30 , and that the inflatable cuffs may be positioned along the length of the assembly  30  at varying distances. In addition, a portion of the plurality of cuffs may be oriented on the assembly  30  to apply a biasing force that urges the assembly  30  in a first direction to extend the assembly  30  into the body passage  730 , while another portion of the plurality of cuffs are oriented on the assembly  30  to apply a biasing force in an opposing second direction to assist in the removal of the assembly  30  from the passage  730 , as will be discussed in greater detail below, in connection with another embodiment. 
     It should also be understood that, although the foregoing embodiment discloses cuffs  800   a  and  800   b  having a variable wall thickness, other means may be used to obtain the differential expansion of the cuffs  800   a  and  800   b  in the manner described. For example, the composition of the material comprising the cuffs  800   a  and  800   b  may be formulated to provide the rear portions  802   a  and  802   b  with greater elasticity, so that greater expansion occurs in these portions, as opposed to the front portions  801   a  and  801   b . Still further, internal structures, such as elastic cords  803  ( FIG. 9 ) or elastic webs  805  ( FIG. 10 ), for example, or other suitable structures, may be incorporated into the cuffs  800   a  and  800   b  that restrain the expansion of the front portions  801   a  and  801   b , while permitting the corresponding rear portions  802   a  and  802   b  to freely expand. 
     The foregoing embodiment advantageously allows an endoscope assembly to develop a longitudinally-directed biasing force that permits the endoscope assembly to be positioned relatively deeply into a body passage, and further permits small, incremental movements of the endoscope assembly when properly positioned within the body passage. The foregoing embodiment further allows the endoscope assembly to be conveniently dislodged in situations where the assembly may become lodged in the passage. 
     As further shown in  FIG. 9 , in yet another embodiment, the assembly  30  may include one or more sleeve members  807  that partially inhibit the expansion of one or more of the cuffs  800   a ,  800   b . In the embodiment shown in  FIG. 9 , the sleeve member  807  is attached to the outer surface of the sheath  130  and partially covers the first cuff  800   a . As the first cuff  800   a  is inflated, the sleeve member  807  allows the rear portion  802   a  of the first cuff  800   a  to expand, and at least partially inhibits the expansion of the forward portion  802   b . The sleeve member  807  may inhibit the expansion of the forward portion  802   b  by any means, including by being relatively less elastic than the first cuff  800   a , or may simply add additional thickness to the forward portion  802   b . Thus, the differential expansion of the cuffs  800   a ,  800   b  may be achieved, and the longitudinally-directed biasing force may be created, in an inexpensive manner by adding one or more sleeve members  807  to the assembly to achieve the beneficial results described above. 
       FIG. 12  is a partial side view of an endoscope assembly  1100  according to still yet another embodiment of the invention. The assembly  1100  includes an inflatable first cuff  1110   a  and a spaced apart inflatable second cuff  1110   b  that are positioned on the outer surface of the sheath  130 . The first cuff  1110   a  and the second cuff  1110   b  may be separately inflated, as described earlier in connection with other embodiments. As in the embodiment shown in  FIGS. 8 through 10 , the first cuff  1110   a  has a non-uniform wall thickness, which includes a forward portion  1111   a , and a rear portion  1112   a  that has a wall thickness that is less than the wall thickness of the forward portion  1111   a . The cuff  1110   b  also has a nonuniform wall thickness, including a forward portion  1112   b  and a rear portion  1111   b . The forward portion  1112   b  has a wall thickness that is less than the wall thickness of the rear portion  1111   b . The non-uniform wall thicknesses of the first cuff  1110   a  and the second cuff  1110   b  permit greater expansion of the portions  1112   a  and  1112   b  of the cuffs  1110   a  and  1110   b  than is obtained in the portions  1111   a  and  1111   b  of the cuffs  1110   a  and  1110   b  when the cuffs  1110   a  and  1110   b  are inflated. The portions  1112   a  and  1112   b  thus develop a longitudinally-directed biasing force when the inflated portions  1112   a  and  1112   b  contact the body passage wall  732 . 
     Turning now to  FIG. 13 , a partial side view of the assembly  1100  is shown with the first cuff  1110   a  at least partially inflated. The rear portion  1112   a  of the cuff  111   a  contacts the passage wall  732  and urges the assembly  1100  along the body passage  730  in a direction  1210 . The cuff  1110   a  may be periodically inflated and deflated to move the assembly  1100  along the passage  730 . 
     Referring now to  FIG. 14 , a partial side view of the assembly  1100  is shown with the second cuff  1110   b  at least partially inflated. The front portion  1112   b  of the cuff  1110   b  contacts the passage wall  732  and urges the assembly  1100  along the body passage  730  in a direction  1220  that is opposite to the direction  1210  shown in  FIG. 13 . 
     The foregoing embodiment advantageously permits the assembly  1100  to be moved along the passage  730  in a direction that positions the assembly  1100  further into the passage  730 , and also permits the assembly  1100  to be moved in the opposite direction, which may be beneficial in preventing the assembly  1100  from being lodged in the passage  730 , in addition to further assisting an operator to precisely position the assembly  1100  within the passage  730 . 
     The above description of illustrated embodiments of the invention is not intended to be exhaustive or to limit the invention to the precise form disclosed. While specific embodiments of, and examples of, the invention are described in the foregoing for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. Moreover, the various embodiments described above can be combined to provide further embodiments. For example, the various embodiments of the inflatable endoscope cuffs as previously described may be advantageously positioned along the length of the endoscope at uniform or varying distances to provide a plurality of inflatable cuffs along the length of the sheath. Further, different embodiments of the inflatable endoscope cuffs as previously described may be positioned at uniform or varying distances along the length of an endoscope to provide a plurality of different cuffs along the sheath to provide still further advantages. For example, the inflatable cuffs may be comprised of different materials or material thicknesses to obtain different inflation rates for the inflatable cuffs and/or different cuff volumes when the inflatable cuffs are inflated by the fluid passage. Accordingly, the invention is not limited by the disclosure, but instead the scope of the invention is to be determined entirely by the following claims.