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Endoscope propulsion system and method

Endoscope propulsion system and method description/claims

The present application relies on, and claims the benefit of the filing date of, U.S. patent application Ser. No. 11/140,595, filed 27 May 2005. Priority of the filing date of this application is claimed, and the disclosure of the application is incorporated herein by reference in its entirety.

1. Field of the Invention

The present invention relates to the field of health care. More specifically, the invention relates to the field of endoscopy, and particularly to devices and methods for performing endoscopic examinations and surgeries.

2. Description of Related Art

Each year, 60,000 Americans die from colon cancer, making colon cancer the second leading cause of cancer death in the United States. Early detection of the disease greatly improves survival. Furthermore, removal of pre-cancerous polyps can be achieved endoscopically, which prevents colon cancer altogether. Unfortunately early colon cancer and polyps are asymptotic. For this reason screening tests are needed to detect and prevent colon cancer. Currently available screening tests include fecal occult blood test, flexible sigmoidoscopy, and colonoscopy. In part because of the limitations of these tests, only about 10% of the United States population is currently screened for this common preventable cause of death.

Fecal occult blood testing detects blood in the stool that can not be seen on visual inspection of the stool. Unfortunately only about 30% of colon cancers can be detected by fecal occult blood testing, making this test too insensitive for effective screening.

Flexible sigmoidoscopy is a type of endoscopy that uses a semi-rigid tube with fiberoptic lenses to directly visualize the colon. The end of this semi-rigid tube has a flexible steering section to direct the instrument's tip. In an ideal patient, this test can visualize up to 60 centimeters of the distal colon (or approximately one-third of the entire colon). The limited extent of the flexible sigmoidoscopy exam misses approximately 50% of colon cancers. Although flexible sigmoidoscopy is insensitive, it is relatively inexpensive and can be performed as a screening test in a physician's office. Unfortunately flexible sigmoidoscopy is too uncomfortable for many patients to tolerate. Flexible sigmoidoscopy is painful because the scope is advanced in the colon by pushing the semi-rigid tube against the colon wall. As the tube is pushed against the colon wall, the colon is stretched. Stretching of the colon causes intense visceral pain. In addition to pain, stretching the colon too far can result in colon perforation, a potentially life threatening complication of flexible sigmoidoscopy.

Colonoscopy, like flexible sigmoidoscopy, is a type of endoscopy that utilizes a semi-rigid tube with either fiberoptic lenses or a video camera to directly visualize the colon. Currently available colonoscopes offer an excellent view of the colon. In a fashion similar to flexible sigmoidoscopy, the semi-rigid tube has a flexible steering section at the distal end of the instrument. Unlike the flexible sigmoidoscope, the colonoscope is long enough to visualize the entire colon. For this reason colonoscopy is ideal for colon cancer screening. If a pre-cancerous colon polyp is detected at the time of colonoscopy it can be removed through the scope's “working channel” using various endosurgical instruments (such as biopsy forceps and polypectomy snares). In a fashion similar to flexible sigmoidoscopy, pushing the semi-rigid tube against the colon wall advances the colonoscope. Unfortunately colonoscopy is far too uncomfortable to be performed without high level intravenous sedation or general anesthesia. The pain experienced during colonoscopy is related to stretching of the colon wall as the colonoscope is advanced. Colon perforation can occur as a result of pushing the semi-rigid tube too forcefully against the colon wall as the colonoscope is advanced. The high level of sedation needed for colonoscopy requires a highly monitored environment, such as an operating room. With the added operating room charges colonoscopy becomes quite costly. If colonoscopy were less expensive, it would be more widely accepted as a colon cancer-screening test.

Various robotic endoscopy devices and methods have been previously disclosed. Several such disclosures involve robotic endoscopes that are generally complex devices with multiple interacting segments. These robotic endoscopes generally involve a kinematically redundant robot, which generally has about seven or more internal degrees of freedom. These robotic endoscopes are also designed to function autonomously as a robot. That is, an examining physician has no direct control of the robotic endoscope. Furthermore, the examining physician can not directly assist in the movement of the scope in an organ lumen. The lack of direct physician control will markedly increase the risks of robotic endoscopy.

The previously disclosed robotic endoscopes also depend on a complicated interaction of a plurality of segments. At least one previously disclosure involves a robotic endoscope that relies on a complex array of pressure sensors, gripping devices, and expansion modules under the control of at least one computer. Even the slightest malfunction of the complex control mechanism could cause devastating complications for a patient.

More specifically, the prior robotic endoscope uses a proximal and a distal toroidal balloon in conjunction with an extensor module. The proximal toroidal balloon expands to statically grip the organ wall and thereby fix this segment of the robotic endoscope to the organ wall. After the proximal balloon has expanded, the extensor module expands, thus lengthening the robotic endoscope. The robotic endoscope depends primarily on the extensor module for movement. After the extensor module has lengthened the robotic endoscope, the distal toroidal balloon expands to fix this segment of the robotic endoscope to the organ lumen wall. After distal toroidal balloon inflation, the proximal toroidal balloon deflates and the extensor module contracts. This arrangement is said to produce an inch-worm-like movement in an organ lumen.

The toroidal balloon described in at least two such prior disclosures operates by means of static friction. This static friction is fundamental to the operation of the robotic endoscope. This static friction is between the balloon and organ wall. The only dynamic feature of the toroidal balloon's operation is expansion and contraction. Extension and contraction of the extensor module causes movement of the robotic endoscope in an organ lumen. As such, the extensor module is the main dynamic component of the robotic endoscope.

The toroidal balloon(s) described in at least these two prior disclosures involve a relatively small surface area. Thus high inflation pressures may be required to grip and fix the toroidal balloon to the organ wall. A high inflation pressure used to fix the toroidal balloon to an organ wall may distend the organ wall. Depending on the degree of organ wall distention, the patient may experience intense visceral pain. Therefore, robotic endoscopy according to these prior devices and methods may often require high level sedation or general anesthesia to permit a comfortable examination. In this regard, robotic endoscopy according to these prior disclosures offers no additional benefits to currently available endoscopic procedures.

Furthermore, the extensor module of these prior robotic endoscope disclosures is constantly changing the axial length of the robotic endoscope. As the robotic endoscope is constantly changing length, currently available endosurgical devices, such as biopsy forceps or polypectomy snares, may be very difficult if not prevented from conjunctive use.

The mechanical complexity of this prior approach and the need for computer control systems generally relate to relatively high production cost for the robotic endoscope. And, as in many fields, high production cost could substantially limit the availability of robotic endoscopy for widespread clinical use, such as in colorectal cancer screening. Moreover, sufficiently high production cost might also prohibit disposal of the robotic endoscope after each use. As disposal would not be generally practical according to these prior approaches, sterilization of the robotic endoscope becomes a likely necessity. Furthermore, sterilizing such a complex device with multiple mechanical and electronic components would be still a further challenge of substantial difficulty. The difficulty in sterilizing these robotic endoscopes could result in elevated potential for infectious disease transmission.

Other medical devices have also been previously disclosed that operate, at least in part, in much the same fashion as the robotic endoscopes just described. At least one additional medical device has been disclosed that uses an expandable front and rear cuff section with an expandable center section to produce movement, sharing certain similarities, including various of the incumbent shortcomings and concerns, with the robotic endoscope noted above. Another lumen-traversing device has also been disclosed that also shares certain similar limitations as the robotic endoscopes noted.

The disclosures of the following issued U.S. patents are herein incorporated in their entireties by reference thereto: U.S. Pat. No. 4,117,847 to Clayton; U.S. Pat. No. 4,207,872 to Meiri et al.; U.S. Pat. No. 4,321,915 to Leighton et al.; U.S. Pat. No. 4,368,739 to Nelson, Jr.; U.S. Pat. No. 4,561,427 to Takada; U.S. Pat. No. 4,615,331 to Kramann; U.S. Pat. No. 4,676,228 to Krasner et al.; U.S. Pat. No. 4,776,845 to Davis; U.S. Pat. No. 5,236,423 to Mix et al.; U.S. Pat. No. 5,259,364 to Bob et al.; U.S. Pat. No. 5,331,975 to Bonutti; U.S. Pat. No. 5,337,732 to Grundfest et al.; U.S. Pat. No. 5,398,670 to Ortiz et al.; U.S. Pat. No. 5,562,601 to Takada; U.S. Pat. No. 5,586,968 to Grundl et al.; U.S. Pat. No. 5,662,587 to Grundfest et al.; U.S. Pat. No. 6,071,234 to Takada; U.S. Pat. No. 6,086,603 to Termin et al.; and U.S. Pat. No. 6,224,544 to Takada. The following U.S. patent application Publications are also herein incorporated in their entireties by reference thereto: US 2002/0143237 to Oneda et al.; US 2003/0225433 to Nakao; US 2004/0106976 to Bailey et al.; and US 2004/0138689 to Bonutti.

Although numerous approaches to developing and implementing endoscopic devices and methods, particularly for colon screening, have been proposed, there is still a need for improved endoscope delivery, in particular relation to colonoscopy. There is, in particular, still a need for an improved system and method that actively propels endoscopes within tortuous body lumens, and in particular the colon and lower GI tract, with improved control and substantially reduced wall trauma and pain. There is also still a need for an improved system and method that modifies commercially available endoscopes for active propulsion along body lumens.

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