FACILITATING ENDOSCOPY

Abstract: A method of inserting an instrument into the gastrointestinal tract of a mammal, by emplacing at least a portion of a flexible liner (50) to form within the intestine an inner tube within an outer tube, the inner tube defining a lumen lying within the intestine and having a distal end accessible via the anal opening from outside the body of the mammal, and thereafter passing the insrument to the lumen via its distal end. Another aspect is the combination of an elongatge evertible liner (50), a liner support chamber (12) having a proximal port (18) and a distal port (22), the liner having its two ends attached respectively at the ports, and a pressurizer for increasing the pressure within the chamber to cause the liner to be everted.

Description: FACILITATING ENDOSCOPY Background of the Invention This invention relates to endoscopy. Colon cancer is the most common visceral malignancy in the United States. There is substantial evidence that nearly all colonic malignancy has its origin in previously benign polyps, and that most colon cancer could be prevented if these polyps could be detected and removed while they are still benign. A diagnostic procedure generally employed when malignancy of the large intestine is suspected is colonoscopy, in which the interior of the colon is examined by means of an elongated flexible fiber optic endoscope, known generally as a colonoscope. A colonoscope for use in transanal colonoscopy is an instrument that typically includes a flexible tube sufficiently long that, when fully inserted into the colon through the anal canal, it can extend through the full length of the colon so that its proximal (inward) end reaches to the cecum. Colonoscopes can be nearly six feet long, and can have a diameter as little as about one-half inch. The proximal tip, that is, the portion about six inches long at the proximal end, is typically maneuver ble by manipulation of controls at the other (distal) end. Incorporated in the tip are a light source and fiber optics for illumination and visual observation; and tools for carrying out irrigation, suction, and surgical procedures such as polyp removal. The procedure most commonly followed for a colonoscopic examination is first to insert the colonoscope by way of the anal canal in a proximal direction into the colon as far as desired, making only a ursory inspection along the way, and then to withdraw the colonoscope distally, while examining the colon more thoroughly, performing biopsies, or removing polyps as appropriate. For an examination of the entire colon, the colonoscope is inserted through the anal opening and the anal canal into the rectum, then advanced through the sigmoid flexure into the descending colon, then from the descending colon through the left colic flexure (the splenic flexure) into the transverse colon, and then from the transverse colon through the right colic flexure (the hepatic flexure) into the ascending colon as far as the caecum. Insertion is effected by maneuvering the colonoscope tip so that it is aimed in the proper direction while (at the distal end) grasping the colonoscope at a point outside the body near the anal opening and pushing inward. The colonoscope is sufficiently stiff that it can be inserted without buckling even when many pounds of pushing force are applied. Advancing the colonoscope tip within the colon is a difficult procedure, and it can be particularly difficult to advance the instrument through the sharp bends of the colon at the sigmoid flexure and the splenic flexure. As the instrument is worked through these bends the sigmoid colon distends and the pressure of the colonoscope on the colon walls tends to stretch that portion of the colon through which the instrument has already passed rather than advancing the tip further into the colon. In some instances, and particularly when the colon has been irritated or sensitized by the movements of the colonoscope within it, reflex action by the colon wall musculature can cause the colon to constrict around the colonoscope during insertion through these bends, aggravating the tendency of the colon to distend lengthwise. Muscle relaxants used to relax the circumferential colonic musculature can prevent this reflex constriction, but such relaxants can also relax the longitudinal colonic musculature, resulting in still further lengthwise stretching of the colon rather than proximal advancement of the colonoscope tip. Insertion of the instrument can be uncomfortable for the patient, and the physician inserting the colonoscope may rely to some extent on the patient's complaints as an indication that the instrument has been misdirected. In cases where the procedure is acutely painful, anesthetics can be used, but they also deprive the physician of the benefit of patient response, and moreover can require postanesthetic recovery procedures. Moreover, there is a substantial risk of perforation of the colon by the tip of the colonoscope during insertion, even when performed by surgeons having some experience with the procedure. Although some surgeons have been able, through care and skill, virtually to eliminate the risk of perforation, there exists a finite rate of complications resulting from diagnostic colonoscopy. Although the inspection itself of the colon, carried out during withdrawal of the instrument, typically takes only about ten minutes' time, insertion of the colonoscope typically takes as much as 50 minutes' time, owing to difficulties in inserting the instrument and because of the care that the physician must take to reduce the likelihood of harm to the patient. Too often the insertion is halted when the tip is at a point far short of the caecum, because a portion of the colon already negotiated by the colonoscope (particularly the sigmoid flexure or the splenic flexure) may constrict tightly upon the colonoscope and prevent further advance. or because the patient cannot tolerate the procedure any further or because the physician is fearful of the danger to the patient, or for some other reason. As a result, the diagnosis is incomplete because a portion of the colon proximally beyond the farthest point reached by the tip escapes examination. It is known to aid inspection of the inner wall of the colon by everting into the colon a flexible tube which remains generally immobile with respect to the colon wall. An object such as a medical instrument can be drawn into the intestine by the everting tube as the eversion of the tube progresses. Summary of the Invention In a general feature of the invention, at least a portion of a flexible liner is emplaced to form within the intestine a first tube within a second tube, the first tube defining a lumen lying within the intestine and having a distal end accessible via the anal opening from outside the body; and thereafter an instrument is passed into the distal end of the lumen. Preferred embodiments include the following features. The flexible liner is emplaced by eversion. One end of the liner is folded back upon itself to form first and second tubes connected along an annular fold; the annular fold is introduced into the anal opening; and the space enclosed between the first and second tubes is pressurized at low pressures not greater than 10 pounds per square inch, preferably less than 3 pounds per square inch. The first and second tubes are collapsed against each other prior to passing the instrument into the lumen. The tubes are collapsed by reducing the pressure in the space enclosed between the first and second tubes. A proximal tip of the instrument is passed through the lumen and beyond a proximal end of the emplaced flexible liner. Preferred embodiments include the following features. The space between the tubes may be pressurized in an oscillating manner during eversion; and successive portions of the inner liner are pulled away from a storage device on which they were gathered. The withdrawal of portions of the liner is aided by mechanically applying intermittent force to the inner liner to free it from the storage device. The varying pressure is applied in coordination with the intermittently applied mechanical force. Specifically, the pressure is decreased when the mechanical force is being applied. The liner storage device includes an internal passage and an external wall supporting the liner, and the force is mechanically applied by means of a tool passed via the storage device passage. In some embodiments, the force is mechanically applied by inflating a balloon against a wall of the liner. In another general feature, the liner comprises a material characterized by having a wall thickness to diameter ratio and a zero strain elasticity modulus whose product is less than 4.0 lb/inch 2 , preferably less than 1.0 lb/inch 2 , and a wall thickness to diameter ratio and a 100% strain modulus of elasticity whose product is greater than 0.5 lb/inch 2 , preferably greater than 2.0 lb/inch 2 . In preferred embodiments, the liner comprises polyurethane or latex; the liner is at least sufficiently long to reach proximally beyond the sigmoid flexure when fully everted within the large intestine, preferably at least 12 inches long; the liner is at least sufficiently long to reach beyond the splenic flexure when fully everted within the large intestine, preferably at least 30 inches long; the distal port is configured and dimensioned to receive a leading end of the instrument; and the distal port is sealed during eversion. In another general feature of the invention, opposite ends of the liner are attached to distal and proximal ports, a portion of the liner is gathered in the space between the ports, the liner defines a lumen between the ports, and a rigid guide tube lying within the lumen and between the ports provides an unobstructed passage for the instrument. In preferred embodiments, a portion of the liner is gathered along and supported by the outside wall of the guide tube, and the tube is straight, and colinear with both of the ports. A mechanism is located in the vicinity of one end of the guide tube for contacting the liner and aiding withdrawal of the liner from the guide tube. The mechanism may include a roller whose outer surface contacts the liner and a support for the roller, the support having a structure for permitting the roller to turn when the liner is being withdrawn from the guide tube, while resisting the turning of the roller when the liner is being moved in the opposite direction. The guide tube has an internal passage and an external wall supporting the liner, and the force is mechanically applied by means of a tool passed via the storage device lumen. In other embodiments, the force is mechanically applied by inflating a balloon against a wall of the liner. In another general feature of the invention, a tube extends distally from the distal port, the end of the liner attached to the distal port is everted over and gathered along the tube, and the pressurizer simultaneously causes the liner to evert beginning near the end attached to the proximal port while enabling the gathered portion of the liner to slide along and be released from the tube. In preferred embodiments, there are means for selectively depressurizing the everted liner. A walled passage is connected to the distal port for bridging the distance from the distal port to the anal sphincter of the patient. The liner forms a pathway for advancing the colonoscope and provides for easier, safer, and less painful insertion of the instrument, reducing the need to use anesthetics during the procedure, and reducing the tendency for stretching, spearing, and distension of the colon during insertion. The invention can substantially reduce the time required for insertion of the instrument, reducing the cost of the procedure and increasing its availability as a diagnostic and preventive measure. The flexible tube can be everted using low fluid pressures, providing safe and gentle lumen-following emplacement of the liner. Once the liner is emplaced, the colonoscope can be slid within the liner lumen, contacting only the inner wall of the liner, so that over the length of the liner it does not contact the colon wall. The inner and outer tubes of the liner may slide freely over one another, during both emplacement of the liner and insertion of the colonoscope, further isolating the movement of the advancing instrument from the colon wall. Other advantages and features will become apparent from the following description of the preferred embodiments, and from the claims. Description of the Preferred Embodiments Drawings Fig. 1 is a perspective view of liner emplacement apparatus. Figs. 2 and 3 are sectional views at 2-2 of Fig. 1 showing two stages of eversion of the flexible tube. Fig. 4 is a rear view of a roller structure for aiding delivery of the everting tube from the guide tube with the colonoscope and outer wall shown in section. Fig. 5 is a front view of a representative roller and its support with the colonoscope and outer wall shown in section. Figs. 6 and 7 are side sectional views showing two positions of a representative roller and its support. Figs. 8 and 9 are sectional views of alternative liner emplacement devices. Fig. 10 is a sectional view, like Fig. 9, with the flexible tube fully everted. Fig. 11 is a perspective view of a liner deployment tool. Figs. 12 and 13 are sectional views of the liner deployment tool in two stages of use. Figs. 14 and 15 are sectional views of an alternative liner deployment aid in two stages of use. Fig. 16 is a sectional view of a clamp for removably clamping the colonoscope to an emplacement device. Fig. 17 is a sectional view, partially broken away, of an alternative emplacement device. Structure and Use Referring to Figs. 1, 2 and 3, a liner emplacement device 10 includes a sterilized, disposable container 12 defined by a cylindrical wall 14 and capped by front and rear walls 15, 16. A port 18 in front wall 15 opens into an external nozzle 20, and a port 22 in rear wall 16 is surrounded by an internal flange 24. A rigid guide tube 26 is affixed to and extends from rear flange 24 forward toward front port 18, and is oriented so that rear port 22, rigid guide tube 26, and front port 18 are generally in axial alignment. Container 10 encloses chamber 32, into which fluid can be pumped from a reservoir (not shown) outside container 10 by way of a fluid port 44 in rear wall 16. A thin-walled flexible elastomeric tube about 3/4 inch in diameter (which when everted will serve as the colon liner) , and about 80 inches long for colonoscopy in an adult human (and, for example, about 36 inches long for sigmoidoscopy) , is made ready for emplacement in the colon generally as follows. One end 52 of flexible tube 50 is mounted over rear flange 24. Initially the major portion 54 (Fig. 2) of tube 50 is stored within chamber 32 by gathering the major portion 54 of tube 50 over guide tube 26. The other end 56 of tube 50 is passed through front port 18 and nozzle 20, and is turned inside out and mounted tightly over free end 21 of nozzle 20. An end 60 of an introducer tube 62 is slipped over tube end 56 so that tube end 56 is tightly held between end 60 of introducer tube 62 and end 21 of nozzle 20. Introducer tube 62 is made of a material, such as for example a polymer, that is sufficiently stiff that it can be inserted transanally beyond the rectal sphincter, yet sufficiently pliable that it does not cause damage to the tissues of the anus or rectum, or undue discomfort to the patient. Introducer tube 62 bridges the distance from the tube end 56 to the anal sphincter of the patient. Now, introducer tube 62 is inserted into the anal canal (not shown) of a patient, and eversion of flexible tubing 50 into the colon is effected as follows. Container 10 is filled with fluid by introducing the fluid into chamber 32 by way of rear fluid input port 44. As the fluid fills chamber 32, tube 50 swells outward, exits nozzle 20, passes through introducer tube 62, and begins to evert at an annular everting margin 70. As tubing 50 everts, margin 70 advances in a forward direction proximally within the colon, in the process forming an outer liner tube 72 and continually drawing, as a trailing tube portion 74, the stored portion 54 of tube 50 from guide tube 26 and out of chamber 32 through front port 18, nozzle 20, introducer tube 62, and outer liner tube 70. By the nature of the eversion process, there is little or no sliding between the outer liner tube 72 and the inner wall of the colon. As trailing tube portion 74 is withdrawn from guide tube 26, that portion of the tube in front of end 28 of guide tube 26 is compressed upon itself by the pressure of the fluid between the trailing tube portion and the outer, already everted outer liner tube 72, while the stored portion 54 of tube 50 is pressed against storage support 26, and is thereby prevented from collapsing upon itself. Referring to Fig. 17, in a preferred embodiment, guide tube 26 (12.5 inches long by 0.688 inches diameter) is supported at one end on a rear port molding 222. Molding 222 has a leading tapered end 224 which tapers to meet the outer wall of guide tube 26. A clamping sleeve 226 is press fit over tapered end 224 to hold one end of the liner (not shown) in place. At the other end of outer wall 14 (13.25 inches long, 1.5 inches diameter), external nozzle molding 220 has a trailing cylindrical portion 226 which extends back beyond the proximal end 228 of guide tube 26 leaving a cylindrical passage 230 through which the liner can pass freely during eversion. Passage 230 is small enough to prevent the passage of kinks or folds in the liner, which could interfere with liner eversion. The inner wall of portion 226 is 0.875 inches in diameter. A second clamping sleeve 232 holds the other end of the liner on the nozzle 220. As shown in Fig. 17, peristaltic pump 31 pumps fluid into chamber 32 from reservoir 33 by way of flexible tubing 35 and coupler 39 through fluid port 44. A pressure gauge 37 is situated between pump 31 and fluid port 44 for monitoring the eversion pressure. The pressure of the everting fluid within the chamber pressing the stored liner against the guide tube can result in a frictional resistance to withdrawing the trailing portion of the tube from the guide tube. As the pressure is increased, any such resistance also increases. As an aid in withdrawing stored tube 54 from guide tube 26, colonoscope 88 is inserted through rear port 22 into space 36 within guide tube 26 and moved frontward, so that its proximal end 89 passes into the lumen 76 of trailing portion 74 of tube 50 and contacts the collapsed tubing wall. Although generally the lumenal surface of the liner has a low frictional coefficient with respect to the colonoscope surface, so that the colonoscope slides easily within the emplaced liner, the fluid pressure presses the collapsed tubing wall against the colonoscope tip, providing some degree of traction between the colonoscope tip and the collapsed tubing wall. As a result, the frontward-moving colonoscope tip can carry this collapsed tubing wall frontward, withdrawing a further trailing portion of the tube from end 28 of guide tube 26. Then colonoscope 88 is moved rearward until its end 89 is withdrawn from trailing portion 74 of tube 50 back to space 36 within guide tube 26. In this fashion, the colonoscope is reciprocally moved back-and-forth, as indicated by arrows a (Fig. 3), between one position, e.g.. Fig. 2, and a second position, e.g.. Fig. 3, aiding with each frontward stroke in withdrawing a further portion of tube 50 from guide tube 26. Moreover, the fluid pressure within chamber 32 can be varied (by a pressure regulator, not shown) to provide pulses of greater pressure alternating with intervals of less pressure, and the pulsations of pressure cooperate with the reciprocal movement of the colonoscope to further assist the colonoscope tip in drawing the stored tube off from the guide tube. As the colonoscope is moved rearward, a pulse of greater pressure is provided, promoting eversion of the tubing and advancement of the everting margin. Then, as the colonoscope is moved frontward, an interval of less pressure is provided, reducing the frictional resistance between the guide tube and the stored tube, and allowing the stored tube to be more easily drawn frontward by the colonoscope. Referring to Figs. 4 through 7, to aid eversion rollers can be provided to press the trailing portion of the tube against the moving colonoscope tip to increase the traction between the colonoscope tip and the collapsed tubing wall of the trailing portion of the tube. As shown in Fig. 4, rollers 101, 102, 103 are in tangential contact with trailing portion 74 of tube 50, so that when colonoscope 88 is passed into tube lumen 76 (Fig. 3), trailing portion 74 of tube 50, is pressed by rollers 101, 102, 103 onto the surface of colonoscope 88. Rollers 101, 102, 103 are supported by roller supports 111, 112, 113, affixed in evenly spaced radial arrangement to cylindrical wall 14 of container 12. Roller supports 111, 112, and 113 are essentially. Roller 101 is rotatably attached by means of shaft 122 to pivoting member 120. Pivoting member 120 is pivotally attached by means of shaft 126 to fixed member 124, which is affixed at 128 to wall 14 of container 12. The axes of shafts 122, 126 are generally normal to a plane passing through 128 and through the long axis of container 12. 0-rings 132 located midway along shafts 122, 126 serve as spacers to inhibit contact between pivoting member 120 and roller 101 and fixed member 124; and retainer pins 130 keep roller 101 and members 120, 124 in place on shafts 122, 126. Roller stop 140 and pivot stop 144 are affixed to fixed member 124 by means of bolt 142 and nut 146. Figs. 6 and 7 show the cooperation of roller 101 and roller support 111 with trailing portion 74 of tube 50 and colonoscope 88 when the colonoscope is moved reciprocally back-and-forth to assist in withdrawing the stored tube from the guide tube. As colonoscope 88 is moved frontward, as indicated by arrow f in Fig. 6, roller 101 presses trailing portion 74 of tube 50 against colonoscope 88 at the point 150 of tangential contact, increasing the friction between the tube wall and the colonoscope, aiding in withdrawing stored tubing 54 off from guide tube 26. As stored tubing 54 is drawn frontward, it causes pivoting member 120 to pivot frontward and it causes roller 101 to rotate as shown by arrow R. As pivoting member 120 pivots frontward, it contacts pivot stop 143, as shown in Fig. 6, whereby further frontward pivoting of member 120 is inhibited. Then, as colonoscope 88 is withdrawn backward, as indicated by arrow b in Fig. 7, the tubing wall is carried backward, owing to traction between it and the colonoscope. This backward movement of the tubing wall causes pivoting member 120 to pivot backward until roller 101 contacts roller stop 140 as shown in Fig. 7, whereby further backward pivoting of member 120 and rotation of roller 101 are inhibited. The cylindrical contact surface of roller 101 is of a material having a high frictional coefficient with respect to tube 50. As a result, as the colonoscope is further withdrawn, tube 74 is inhibited by contact with stopped roller 101 from further movement backward, and as the traction between the colonoscope and the tube is thereby overcome, the colonoscope slides rearward out from the trailing portion of the advancing tube. Further reciprocation of the colonoscope into the lumen of the collapsed trailing portion of the tube follow, withdrawing further stored tubing from the guide tube, until the tubing has been everted to the desired extent. When eversion of tube 50 has proceeded to the desired point, the source of fluid to rear port 44 is removed, or the pressure in chamber 32 is allowed to drop, so that the fluid is allowed to drain out from container 10 through rear port 44. This relieves the pressure that had compressed the trailing portion of the everting tube to collapse upon itself during eversion, and permits inner liner tube 74 of everted tube 50 to collapse upon outer liner tube 72 of everted tube 50. Then the colonoscope 88 can be introduced through rear port 22, through the space 36 within guide tube 26, and through the lumen 76 formed by the inner surface of inner liner tube 74 of fully everted tube 50, sliding along the lumen 76 of the fully everted liner. Thus, less than the full length of the liner can be emplaced if desired, leaving the tube in part on the guide tube, and permitting insertion of the colonoscope through the still-stored portion by way of rear port 22 and the enclosed space 36 within storage support 32. Referring to Figs. 9 and 10, alternatively the guide tube may be eliminated, and the tubing may be stored by coiling or stacking it loosely in the chamber. Apart from the lack of a guide tube the tubing is made ready for emplacement generally as described above with reference to Fig. 2. The embodiment of Figs. 9 and 10 has the advantage of being structurally simpler than the embodiments shown in Figs. 2 through 8; but it has the disadvantage, as will be apparent from the description below with reference to Fig. 10, that the full extent of the tubing must be everted before the colonoscope can be inserted through it, because the colonoscope cannot pass through the folds and turns of the coiled or stacked stored tubing. In use, introducer tubing 62 of Figs. 9, 10 is inserted into the anal canal of the patient, and flexible tube 50 is everted into the colon as follows. A plug 23 is fitted into rear port 22, and chamber 32 is filled with fluid via port 44 and conduit 46. As the fluid fills chamber 32, flexible tube 50 collapses, as shown in Fig. 9. As the fluid pressure is increased, tube 50 begins to evert at an annular everting margin 70. As tubing 50 everts, margin 70 advances into the colon, and in the process forms an outer liner tube 72 and continually draws a trailing tube portion 74 from storage chamber 32 in effect providing a double walled liner within the colon. By the nature of the eversion process, there is little or no sliding between the outer liner tube 72 and the inner wall of the colon. Referring to Fig. 10, when tube 50 is completely everted, the source of fluid is disconnected from rear input port 44 and the fluid allowed to drain from container 12. This permits trailing tube portion 74, which now constitutes an inner liner tube, to collapse upon outer liner tube 72 of everted tube 50. Then plug 23 is removed from rear port 22, and the colonoscope 88 is introduced, as shown generally by arrow i, through rear port 22 and through the lumen 76 formed by the inner surface of inner liner tube 74 of fully everted tube 50, sliding along the lumenal surface of the fully everted liner. The flexible tube forming the liner preferably is thin and is of an elastomeric material having a low initial modulus of elasticity; that is, initially the wall is easily stretched so that only low fluid pressures are required for eversion. Preferably, the product of the tube wall thickness to diameter ratio and the initial (that is, at zero strain) modulus of elasticity is less than 4 pounds per square inch, and more preferably less than 1 pound per square inch. The tube preferably has limited distensibility, so that it does not "balloon", which would cause distension and stretching of the colon during eversion. The tube preferably is of a tough material, so that it resists spearing and penetration by the colonoscope during insertion of the instrument. Preferably, the product of the liner wall thickness to diameter ratio and the 100% strain modulus of elasticity is greater than 0.5 pound per square inch and more preferably greater than 2 pounds per square inch. The walls of the tube preferably have a low coefficient of friction, both with respect to one another, so that they move easily against one another during eversion, and with respect to the colonoscope, so that the colonoscope does not bind as it slides through the lumen of the liner. Polyurethane is a preferred tube material, as it has low distensibility (that is, stress rises rapidly and non-linearly with strain) , and is tough and penetration- resistant. For colonoscopy, preferably a polyurethane liner has a diameter between about 1/2 inch and 1 inch, and a wall thickness between about 0.002 inch and 0.007 inch. Polyurethane tube about 3/4 inch in diameter and having a wall thickness 0.003 inch formed by dielectric sealing of 3 mil polyurethane sheet can be everted using fluid pressures of a few pounds per square inch, when lubricated as described further below. Latex rubber is also a suitable tube material for low pressure eversion. Preferably a latex liner has an inner diameter between about 1/2 inch and about 1 inch, and a wall thickness between about 0.010 inch and 0.030 inch. Latex tube about 3/4 inch in diameter and having a wall thickness 0.015 inch can be everted using fluid pressures in the range 1 - 2 pounds per square inch when well-lubricated. Latex is less preferred than polyurethane, however, as latex is more easily stretched and distended than polyurethane. As noted above, the fluid pressure for effecting eversion causes the stored portion of the tubing to collapse upon itself. Without lubrication, the collapsed tubing walls stick to one another with a force that increases with increasing pressure, so that it is necessary to use tube materials having a low coefficient of friction, or to provide a lubricant that is sufficiently viscous that it is not substantially displaced from the contacting wall surfaces under the pressure of the fluid. Moreover, the everting fluid itself must have some degree of lubricity to aid in minimizing the friction between the collapsed, not yet everted, inner portion of the tube and the everted outer portion of the tube as the inner portion slides against the outer portion during eversion. The viscosity of the everting fluid must be low enough to minimize the pressure drop between the chamber and the everting margin. For latex liner materials, a preferred lubricant for the everting fluid is an aqueous hydrogel such as, for example, K-Y Jelly mixed with water in a proportion as great as about 30% jelly, and preferably between about 1:10 and 1:5. A preferred lubricant for the contacting surface of the collapsed tubing is an aqueous hydrogel such as, for example, K-Y Jelly and water in a proportion at least about 1:2. An aqueous hydrogel can be suitable for a lubricating everting fluid for a polyurethane liner as well, as described generally in, for example, D.R. Shook et al., 1986, Trans. ASME, Vol. 108, pp. 168-74. More preferably the coefficient of friction of polyurethane tube and/or of the guide/storage tube is reduced by coating the wall surfaces with a hydromer such as, for example, polyvinylpyrrolidone ("PVP") , which has a very low coefficient of friction when wet, as described generally in, for example, D.R. Shook et al., 1986, Trans. ASME, Vol. 108, pp. 168-74. Means other than the colonoscope can be passed through rear port 22 into space 36 within guide tube 26 and reciprocated back-and-forth to aid in withdrawing stored tube 54 from guide tube 26. For example, any device configured like the colonoscope tip can be used substantially as described above. Referring to Figs. 11 through 13, each of four feet 306 is attached to one end of a curved leg 304, and the other end of each leg is affixed to an end of a handle 302. Legs 304 are constructed of a resilient material, and are affixed to handle 302 so that the legs mutually diverge and so that when the legs or the feet are forced toward the axis the resilience of the legs tends to urge the feet divergently apart. Referring to Figs. 12 and 13, the legs 304 can be gathered toward the axis A-A of the handle 302, inserted feet foremost into the rear port 22 of the container, and pushed frontward within the guide tube 26. The resilience of the legs presses the feet divergently outward, so that the feet slide against the lumenal surface of the guide tube as the handle is pushed frontward until the feet 306 reach beyond the front end 28 of the guide tube 26. Then the resilience of the legs forces the feet against the liner tube. A radially outward surface 308 of each foot is provided with a material that has a high coefficient of friction with respect to the tube wall. As the handle is pushed further forward, the liner tube is carried forward by the feet, and it is drawn off from the guide tube. Then, as the handle is withdrawn rearward (Fig. 13), the legs engage first the end 28 and then the lumenal surface of the guide tube 26, which compresses the legs toward the handle axis, causing the feet to lose contact with the liner tube. The handle 302 is reciprocated in this manner frontward and rearward as fluid is introduced under pressure into the container as described above, and the reciprocating action helps to withdraw the tube from the guide tube as the liner is everted. An alternative liner deployment device is shown in Fig. 14. An expandable balloon 402 is removably affixed in sealed relation to one end 404 of a hollow tubular handle 406, and a compressible bulb 410 is removably affixed in sealed relation to the other end 408 of handle 406. The bulb, tube, and balloon are filled with a fluid such as air or water during assembly, so that compression of the bulb results in displacement of the fluid and expansion of the balloon. The tubular handle and the balloon, when deflated, are dimensioned to pass within the guide tube 26. The liner deployment device is inserted, balloon first, through the rear port and through the lumen of the guide tube until the balloon emerges from the end 28 of the guide tube 26. Then the bulb 410 is compressed, expanding the balloon 402 and bringing the balloon into contact with the liner tube 50 (Fig. 14) . As the device is moved further frontward, the liner is withdrawn by the balloon from the guide tube. Then the bulb is released, the balloon deflates so that it loses contact with the liner, and the device is withdrawn rearward (Fig. 15) . As the device is reciprocally inflated and moved frontward as in Fig. 14 and then deflated and moved rearward as in Fig. 15, while fluid is passed into the container under pressure, the liner 50 is progressively withdrawn from the guide tube 26 as the liner everts. In a preferred embodiment, tube 406 is made of a polymer such as lucite; balloon 402 is made of an elastomer having a high coefficient of friction with respect to the liner tube, such as latex; and bulb 410 is made of a material such as rubber,having sufficient resiliency that when not compressed, it tends to assume its fully inflated configuration. Balloon 402 and bulb 410 are press-fitted over the respective ends of tube 406, and secured if desired with annular clamps. Referring to Fig. 8, in an alternative guide tube arrangement, the tube storage support may be topologically situated toward that surface of the tube which is contacted by the everting fluid, so that increased pressure of the everting fluid lifts the stored tubing away from the storage support and reduces the frictional resistance of the tubing with the storage support. In this embodiment, the liner emplacing apparatus includes a generally cylindrical housing 200 having cylindrical wall 202, front end face 204, and rear end face 206. Port 203 in front end face 204 is surrounded by nozzle 220 over which introducer tubing 262 is tightly affixed, and port 205 in rear end face 206 is surrounded by internal flange 207. Situated generally transversely within cylindrical container 200 are front bulkhead 214, which is provided with port 222; rear face port 205, bulkhead port 222, front face port 203, and front nozzle 220 are generally axially aligned. Fluid conduit 246 connects fluid input port 248, provided in rear face 206, to fluid input port 244, provided in bulkhead 214, so that fluid can be conducted from outside housing 200 to a chamber 230, which is enclosed between front face 204 and bulkhead 214. Bulkhead 214 is affixed in sealed relation to cylindrical wall 202. Projecting rearwardly from rear bulkhead port 222 toward and generally aligned with rear face port 205 and flange 207 is tube storage support 292. Flexible tube 250 is made ready for emplacement in the colon by drawing one end 252 of tube 250 over storage support 292, affixing end 252 of tube in sealed relation upon storage support 292 near bulkhead 214, and gathering the major portion 254 of tube 250 over storage support 292; passing the other end 256 of tube 250 through the space 294 enclosed by storage support 292, through bulkhead port 222, and through the lumen of nozzle 220; and turning the other end 256 of tube 250 inside out and mounting it tightly over the free end 221 of nozzle 220. An end 260 of introducer tube 262 is slipped over tube end 256 so that tube end 256 is tightly held between end 260 of introducer tubing 262 and end 221 of nozzle 220. Now, as described above with reference to Figs. 2 and 3, introducer tubing 262 is inserted into the anal canal (not shown) , and eversion of the flexible tubing into the colon is effected as follows. A stopper 300 is placed into rear face port 205, and chamber 230 is filled with fluid by introducing the fluid into chamber 230 by way of rear fluid input port 248, conduit 246, and fluid input port 244. Here, however, as the fluid fills chamber 230, the stored portion 254 of tube 250 is lifted by fluid pressure away from storage support 292; and pressure of the tube against storage support 292 is prevented. As chamber 230 becomes filled with the fluid the pressure of additional fluid causes tube 250 to begin to evert at everting margin 270. Stopper 300 prevents eversion of the tube in a rearward direction; that is, no everting margin advances in a direction along tube 250 away from tube end 252. As further fluid is introduced by way of rear fluid port 244 into chamber 230, and as tubing 250 continuously everts, everting margin 270 advances as described above in a forward direction proximally within the colon, forming an outer liner tube 272 and continually drawing the stored portion 254 of tube 250 off from storage support 292 around annular end 293 of storage support 292 through the space 294 enclosed by storage support 292, through bulkhead port 222, and through front face port 203, nozzle 220, introducer tubing 262, and outer liner tube 272. When eversion of tube 250 has proceeded to the desired point, the source of fluid to fluid input port 244 is removed and the fluid allowed to drain out from chamber 230 by way of conduit 246 and fluid input port 248. This permits inner liner tube 274 of everted tube 250 to collapse upon outer liner tube 272 of everted tube 250. Then stopper 300 is removed from rear face port 205, and the colonoscope can now be introduced through rear face port 205, and through the lumen 276 formed by inner surface of inner liner tube 274 of everted tube 272, sliding along lumen 276 of the fully everted liner. Other embodiments are within the following claims. Other liner materials can be used, such as natural and synthetic rubber, silicone rubber, polyethylenes, segmented polyurethanes, polyolefins such as polyethylene and polypropylene, copolymers of ethylene or propylene and vinyl acetate, polyvinyl chloride or copolymers of vinyl chloride and the like. The tubing can be reinforced using, for example, materials such as synthetic fibers or threads derived from cotton, silk, nylon, polyester, and the like. Other lubricants can be used, such as water alone, water containing hydroxyethylcellulose (for example, Natrosol®) or other water "thickeners" such as other cellulose derivatives and glycerine, water containing a surfactant or a mixture of surfactants, or mineral or vegetable oil. The dimensions of the liner can be selected to adapt the apparatus for human pediatric use, as well as for veterinary uses in any of various mammals. It will be appreciated that the liner can be used to facilitate insertion of instruments other than a colonoscope and to facilitate insertion of instruments such as, for example, endoscopes, into body passages other than the colon. A liner tube having a diameter about 3/4 inch and a length at least 80 inches, as described above, can form an everted liner having a length at least 30 inches when fully everted within the intestine using a liner emplacement device as described above, suitable for colonoscopy in an adult human. A shorter liner tube having a diameter about 3/4 inch can form a liner having an everted diameter as described for colonoscopy and an everted length about 12 inches, suitable, for example, to facilitate insertion of a sigmoidoscope. Once the liner has been emplaced and the colonoscope has been fully inserted, it can be preferable to withdraw the liner and the colonoscope concurrently. A clamp is shown in Fig. 16 for removably affixing the colonoscope to the container at the rear port, so that withdrawal of the container away from the patient can effect withdrawal of the liner and the colonoscope together. In this embodiment a threaded rearwardly projecting external flange 420 is provided at rear port 22, onto which a threaded nut 422 can be affixed. A compressible O-ring 424 is held between a rearward surface 421 at the end of flange 420 and a frontward surface 423 of nut 422, so that O-ring 424 can be compressed when nut 422 is turned as flange 420, pressing O-ring 424 against the surface of colonoscope 88 and clamping the colonoscope concentrically in place.

Claims: Claims 1. A method for inserting an instrument into the large intestine of a mammal, in which at least a portion of a flexible liner is emplaced to form within the intestine an inner tube within an outer tube, said inner tube defining a lumen lying within the intestine and having a distal end accessible via the anal opening from outside the body of the mammal, and thereafter said instrument is passed into said lumen via its said distal end. 2. The method of claim 1 wherein said flexible liner is emplaced by eversion. 3. The method of claim 1 wherein said eversion is achieved by folding one end of said liner back upon itself to form said inner and outer tubes connected along an annular fold, and introducing said fold into the anal opening. 4. The method of claim 1 further comprising pressurizing the space enclosed between said inner and outer tubes. 5. The method of claim 4 in which said space is pressurized at low pressures no greater than 10 pounds per square inch, preferably less than 3 pounds per square inch. 6. The method of claim 1 in which said inner and outer tubes are collapsed against each other prior to said instrument being passed into said lumen. 7. The method of claim 6 wherein said tubes are collapsed by reducing the pressure in the space enclosed between said tubes. 8. The method of claim 1 further comprising passing a proximal tip of said instrument through said lumen and beyond a proximal end of said emplaced flexible liner. 9. The method of claim 1 wherein, prior to eversion, said inner tube is at least partially gathered on a storage device, and during eversion the withdrawal of portions of said liner from said storage device is aided by applying mechanical force to said inner liner to free it from said storage device. 10. The method of claim 9 wherein said mechanically applied force is applied only intermittently. 11. The method of claim 10 wherein said space is subjected to varying pressure in coordination with said intermittently applied mechanical force. 12. The method of claim 11 wherein said pressure is decreased when said mechanical force is being applied. 13. The method of claim 9 wherein said storage device comprises an internal passage and an external wall supporting said liner, and said force is mechanically applied by means of a tool passed via said storage device passage. 14. The method of claim 13 wherein said force is mechanically applied by inflating a balloon against a wall of the liner. 15. Apparatus for inserting an instrument into the large intestine of a mammal, comprising an elongate evertible liner, a liner support chamber having a proximal port and a distal port, said liner having its two ends attached respectively at said ports, and a pressurizer for increasing the pressure within said chamber to cause said liner to be everted, said liner comprising a material characterized by having a wall thickness to diameter ratio and a zero strain elasticity modulus whose product is less than 4.0 lb/inch 2 , preferably less than 1.0 lb/inch 2 , and a wall thickness to diameter ratio and a 100% strain modulus of elasticity whose product is greater than 0.5 lb/inch 2 , preferably greater than 2.0 lb/inch 2 . 16. The apparatus of claim 15 wherein said liner comprises polyurethane or latex. 17. The apparatus of claim 15 wherein said liner is at least sufficiently long to reach proximally beyond the sigmoid flexure when said liner is fully everted within the large intestine. 18. The apparatus of claim 15 wherein said liner is at least sufficiently long to reach proximally beyond the splenic flexure when said liner is fully everted within the large intestine. 19. The apparatus of claim 15 wherein said liner is at least 12 inches long when said liner is fully everted within the large intestine. 20. The apparatus of claim 15 wherein said liner is at least 30 inches long when said liner is fully everted within the large intestine. 21. The apparatus of claim 15 wherein said distal port is configured to receive a leading end of said instrument. 22. The apparatus of claim 15 further comprising means for sealing said distal port during eversion. 23. Apparatus for inserting an instrument into the large intestine of a mammal, comprising an elongate evertible liner, a liner support chamber having a proximal port and a distal port, opposite ends of said liner being attached respectively to said ports, at least a portion of said liner being gathered in the space between said ports, said liner defining a lumen between said ports, and a rigid guide tube lying within said lumen and between said ports to provide an unobstructed passage for said instrument within at least a portion of said lumen. 24. The apparatus of claim 23 wherein a portion of said liner is gathered along and supported by the outside wall of said guide tube. 25. The apparatus of claim 24 further comprising a mechanism located in the vicinity of one end of the guide tube for contacting the liner and aiding withdrawal of the liner from the guide tube. 26. The apparatus of claim 25 wherein said mechanism comprises a roller whose outer surface contacts the liner and a support for the roller, the support having a structure for permitting the roller to turn when the liner is being withdrawn from the guide tube, while resisting the turning of the roller when the liner is being moved in the opposite direction. 27. The apparatus of claim 23 wherein said tube is straight, and colinear with both of said ports. 28. Apparatus for inserting an instrument into the intestine of a mammal, comprising an elongate evertible liner, a liner support chamber, said chamber having a distal port and a proximal port, a tube extending distally from said distal port, said liner having its opposite ends attached respectively to said ports, the end of said liner attached to said distal port being everted over and gathered along said tube, and a pressurizer for increasing the pressure within said liner during eversion to aid the gathered portion of said liner to slide along and be released from said tube. 29. The apparatus of claim 15, 23, or 28 further comprising means for selectively depressurizing said liner while said liner is everted. 30. The apparatus of claim 15, 23, or 28 further comprising a walled passage connected to said distal port for bridging the distance from said distal port to the anal sphincter of the mammal. 31. The apparatus of claim 15, 23, or 28 further comprising a walled passage connected to said distal port for bridging the distance from said distal port to the anal sphincter of the mammal, said walled passage having walls made of a pliable material.

Inventors: BLANCO ERNEST E, HERNANDEZ MARIA L, MIX THOMAS W, ROSSKOTHEN NORMAN, VINEYARD GORDON C, BLANCO, ERNEST, E., HERNANDEZ, MARIA, L., MIX, THOMAS, W., ROSSKOTHEN, NORMAN, VINEYARD, GORDON, C.
Applicants: MERIX CORP, MERIX CORPORATION
Application year: 1989
Main classification: A61B1
IPC codes: A61B1