Abstract:
An endoscopic device for locomotion in a body cavity according to a prefixed advancing direction (A) comprising at least a variable length intermediate section ( 1   a,    21   a ) extending between a front end section ( 1   b,    21   b ) and a rear end section ( 1   c,    21   c ). First and second clamping means ( 7, 12, 27, 32 ) are integral to the front and rear section, for alternately grasping respective surrounding portions of wall (P) of the body cavity. Sucking means (13, 14, 37, 38) are associated to the first and second clamping means for creating a depression sufficient to cause the body cavity wall portions to collapse within the first and second clamping means while they are in an open condition. Means for actuating alternate extensions and retractions of the intermediate section and actuating means ( 6, 11, 26, 31 ) of the first and second clamping means are further provides for synchronous operation to generate a forward motion of the rear end section due to a retraction of the intermediate section, the wall portion (P) surrounding the first clamping means being firmly held therebetween, and to generate a forward motion of the front end section due to an extension of the intermediate section, the wall portion (P) surrounding the second clamping means being firmly held therebetween.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to an endoscopic device for locomotion through a tubular body cavity, in particular, but not exclusively, through the gastrointestinal tract, able to migrate in a prefixed direction with so-called inchworm motion.  
         BACKGROUND OF THE INVENTION  
         [0002]    Endoscopic devices for surgical or diagnostic procedure are already known. These devices are operated by the surgeon who directly imparts to the device the forward motion through the patient&#39;s body. Surgical and/or diagnostic instruments which are necessary to carry out each specific procedure, such as microarms, microcameras, and/or laser emitters are generally associated to these devices.  
           [0003]    In order to make easier the surgeon&#39;s task there have been proposed endoscopic devices of the above mentioned type capable of a semi-autonomous movement within the body cavity of a patient, adapting their shape, as far as possible, to the shape of the surrounding cavity. In this case, the walls of the body cavity act as a support for propelling the device forward. For example, in U.S. Pat. No. 5,398,670 there is disclosed an endoscopic instrument substantially formed by a bellows-shaped tubular body, capable of extension and retraction, and by two end portions including respective inflatable balloon members, by means of which the front end portion and the rear end portion alternately engage by compression with the walls of the body cavity through which the device must be pushed forward. There is provision for a control system which operates the inflation and deflation of the two balloon members and the extension and retraction of the tubular body according to a sequence such as to produce the advancement of the device in the prefixed direction.  
           [0004]    An endoscopic device of the same type is disclosed in U.S. Pat. No. 5,906,591, in which, however, a vacuum pressure sufficient to produce, under the induced sucking conditions, a substantial anchorage of the front and rear end portions to the cavity wall is created sequentially around these end portions.  
           [0005]    When the endoscopic device of the type described in the above cited patents is destined to the locomotion through the gastro-intestinal tract, its anchorage to the cavity walls is not satisfactory, because this type of cavity is soft, slippery and often wet. Using balloon-type endoscopic devices such that according to U.S. Pat. No. 5,298,670, even if the intestinal wall is overextended, it is impossible to produce sufficient traction forces due to extremely low friction coefficient of the gastrointestinal tract. Furtheremore, excessive overextension of the balloon will result in causing severe pain for the patient. A similar result is obtained by increasing the suction in the case of the endoscopic device of U.S. Pat. No. 5,906,591, with the drawback that, when the degree of vacuum is increased over a certain extent, undesirable lesions may appear.  
           [0006]    In order to improve the anchorage of the endoscopic devices of the above mentioned type it has proposed to equip them with auxiliary anchoring means of various shapes, which, however, increase the structural complexity and the length of the device and increase the patient discomfort and the risk of damage of the involved tissues.  
         SUMMARY OF THE INVENTION  
         [0007]    The object of the present invention is to provide an endoscopic device of the semi-autonomous locomotion type through a body cavity such as the gastro-intestinal tract, capable of assuring a suitable anchorage to the body cavity thereby allowing its advancement through it, without giving rise to any of the problems encountered with the similar known devices.  
           [0008]    Another object of the present invention is to provide an endoscopic device of the above mentioned type for achieving a suitable anchorage to the cavity wall by means of structurally simple solutions allowing the size of the device to be kept small.  
           [0009]    These object are reached with the endoscopic device for locomotion in a body cavity in a prefixed advancement direction according to the present invention, comprising at least a variable length intermediate section extending between a front end section and a rear end section with respect to said direction and first and second clamping means integral to the front end section and, respectively, the rear end section, for selectively grasping respective surrounding portions of the wall of the body cavity. Associated to the first and second clamping means suction means are provided for creating a vacuum sufficient to cause the surrounding portions of the body cavity walls to collapse within the first and the second clamping means, when they are in their open condition, to allow a firm grasping when said clamping means are closed. Means For operating alternate elongations and retractions of the intermediate section and means for operating the first and second clamping means, synchronously operated to cause an advancement of the rear end section device in the prefixed direction following a retraction of the intermediate section when the respective portion of surrounding wall is firmly engaged with the first clamping means, and to cause an advancement of the front end section in the same direction following an elongation of the intermediate section when the respective surrounding wall portion is firmly engaged within the second clamping means.  
           [0010]    Furthermore, the present invention provides a method for producing the locomotion through body cavities of an endoscopic device, by means of successive extensions and retractions of at least one variable length intermediate section thereof according a prefixed direction defining front end section and a rear end section of the device, to which first and second clamping means are respectively associated selectively operable from the outside synchronously with the successive extensions and retractions of the intermediate section. The method is characterized by inducing selectively by suction a pneumatic depression in correspondence to one of the first or the second clamping means in their open condition, the depression being such that to cause the surrounding portion of body cavity wall to collapse within said clamping means, and closing said clamping means to grasp said surrounding wall portion and firmly anchoring to it the respective end section to allow the free movement of the other end section in the prefixed direction.  
           [0011]    The main advantage of the endoscopic device of the invention consists in that it can migrate through a tubular body cavity in every condition whatever the available friction forces and the compliance of the body cavity are 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    Further characteristics and advantages of the endoscopic device according to the invention will become more apparent from the following description of exemplifying, not limiting embodiments thereof, made with reference to the annexed drawings, in which:  
         [0013]    [0013]FIG. 1 is a longitudinal sectional view of a first embodiment of the endoscopic device according to the present invention;  
         [0014]    [0014]FIGS. 2 a - 2   k  show and advancement cycle of the device of FIG. 1;  
         [0015]    [0015]FIG. 3 is a longitudinal sectional view of a second embodiment of the device according to the present invention;  
         [0016]    [0016]FIG. 4 is a cross sectional view of the endoscopic device of FIG. 3 taken along arrows IV-IV;  
         [0017]    [0017]FIG. 5 is a longitudinal sectional view of the endoscopic device of FIG. 3 taken along arrows V-V of FIG. 4;  
         [0018]    [0018]FIGS. 6 a ,  6   b ,  6   c  schematically show the operation of the clamping means integral to the rear end of the endoscopic device of FIG. 3;  
         [0019]    [0019]FIGS. 7 a ,  7   b  schematically show the operation of the clamping means integral to the front end of the endoscopic device of FIG. 3;  
         [0020]    [0020]FIGS. 8 a - 8   g  show and advancement cycle of the endoscopic device according to FIG. 3. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]    With reference to FIG. 1, it has been generally indicated at  1  an endoscopic device according to the present invention. It comprises an intermediate section  1   a  of a tubular shape, extending between two end sections called front end section  1   b  and rear end section  1   c , the terms “front” and “rear” being referred to a reference direction indicated at k. Clearly, the endoscopic device will be able to move in the body cavity in a forward and a backward direction. The tubular intermediate section  1   a  is formed by a wall  2  made of elastic and flexible material shaped like a bellows and delimiting a cavity  3  for containing a fluid, for example air. The intermediate section ends with a front flange  2   a  and a rear flange  2   b  through which it is connected to front end section  1   b  and rear end section  1   c  respectively.  
         [0022]    Front end section  1   b  of the device is formed by a stem  4  fixed to front flange  2   a  at a flanged end  4   a  thereof and to a front head  5  of the device at the other end. Fixed to flanged end  4   a  of stem  4 , at the opposite side of flange  2   a , is a bellows member  6  which is integral to a jaw  7   a  of a first clamp  7  (also called front clamp) slidably mounted on stem  4  and fixed to the free end of bellows  6 . The other jaw  7   b  of first clamp  7  is constituted by a face of front head  5  perpendicular to the axis of stem  4  and faced toward first jaw  7   a.    
         [0023]    Rear end section  1   c  is formed by a rear head  8 , from which a tubular connector  9  extends, connected to a flanged end  10   a  of a stem  10 . Fixed to flanged end  10   a , at the opposite side of rear head  8 , is a bellows member  11  integral to a jaw  12   a  of a second clamp  12  (also called rear clamp) coaxially and slidably mounted on stem  10 , the other jaw  12   b  of second clamp  12  being formed by a plate fixed to the end of stem  10  at one side thereof and to rear flange  2   b  of intermediate section  1   a  at the other side.  
         [0024]    Tubular connector  9  puts into communication the device with an external control system, of the conventional type, for example as described and shown in FIG. 3 of U.S. Pat. No. 5,906,591, comprising a source ( 50 ) for selectively providing a positive or negative pressure to the various parts of the devices as will be explained below. More precisely, connector  9  houses pneumatic conduits extending in a substantially axial way within device  1  (as schematically shown in FIG. 1), each of them being able to both feed compressed air to and suck air from chamber  3  of bellows-shaped intermediate section  1   a  (conduit  40 ), bellows member  6  and  11  controlling the operation of clamps  7  and  12  (conduits  41 , 42 ), as well as to/from a surface portion of stems  4  and  10  comprised between jaws  7   a ,  7   b  and  12   a ,  12   b , respectively, of clamps  7  and  12 , through diametral ducts  13  and  14  extending from respective axial ducts  15  and  16  formed in stems  4  and  10 , communicating with respective pneumatic conduits housed within connector  9 . A further pneumatic conduit.  43  outflows from front heaad  5  to blow air jets useful to assisting forward motion of the device. In particular, pneumatic conduits passing through intermediate section  1   a  are helically arranged within chamber  3  as schematically indicated at  44  in FIG. 1.  
         [0025]    The operating cycle of the endoscopic device is now described with reference also to FIGS. 2 a - 2   k  (the parts being in turn under pressure are shown as hatched). By creating suction conditions at rear clamp  12  a substantially annular portion P of the surrounding wall of the body cavity is caused to collapse between jaws  12   a, b  which, by adduction of compressed air within bellows  11 , close against each other firmly grasping wall portion P (FIG. 2 a ). Through radial duct  13  of stem  4  air is blown against cavity wall P to cause its displacement from front end section  1   b  of the device (FIG. 2 b ). Then compressed air is fed to bellows  2  which elongates pushing front end section  1   b  of the device forward (FIG. 2 c ). At this point, a depression is created between jaws  7   a, b  of front clamp  7  which causes a substantially annular portion of the surrounding cavity wall P to collapse therebetween. By adducting compressed air bellows  6  is caused to elongate and clamp  7  closes firmly grasping cavity wall (FIG. 2 e ). Bellows  11  is then retracted by depression to open clamp  12  (FIG. 2 f ) releasing the grasped cavity wall which is displaced back from rear end section  1   c  of the device by means of air jets through radial duct  14  of stem  10  (FIG. 2 g ). Rear end section  1   c  is then pulled forward by bellows  2  which retracts due to depression induced therein (FIG. 2 h ). At this point, rear clamp  12  grasp a new annular portion of surrounding cavity wall P by creation of a depression between jaws  12   a ,  12   b  (FIG. 2 i ) and closure of rear clamp  12  (FIG. 2 j ), while front clamp  7  opens to release the grasped annular wall portion. Then the cycle is repeated with a new advancement step.  
         [0026]    In order to improve the grip of jaws  7   a ,  7   b  and  12   a ,  12   b  of front clamp  7  and rear clamp  12  respectively, a circular groove  17  is formed on one of their opposed faces and a corresponding step  18  for engaging with groove  17  is formed on the other face. Advantageously all the edges of the grip surfaces are beveled to avoid any tissue damage.  
         [0027]    A second embodiment of the endoscopic device according to the invention is shown in FIGS. 3, 4,  5 ,  6   a - c  and  7   a,b . In the figures,  21   a  indicates an intermediate tubular section of the device formed by a bellows wall  22  made of elastic and flexible material delimiting a chamber  23 ,  21   b  indicates a front end section connected to intermediate section  21   a  through a front flange  22   a  and  21   c  indicates a rear end section connected to intermediate section  21   a  through a rear flange  22   b.    
         [0028]    Front end section  21   b  comprises a head  25  conected to front flange  22   a  and integral to a stem  24  axially extending through intermediate section  21   a  and rear end section  21   c  and connected to a tubular connector  29 . A first clamp  27  is mounted at the end of stem  24  opposite to that where head  25  is fixed. Each clamp is formed by a jaw  27   a  axially slidable on stem  24  and by a jaw  27   b  fixedly connected thereto. Jaw  27   a  and  27   b  are each formed by a pair of jaw portions diametrically arranged on stem  24 . The two portions of jaw  27   a  are mutually connected by means of a bracket  28  passing through a slot  30  diametrically formed in stem  24 . An actuating wire  26  crosses bracket  28  in two points and is fixed to the bracket at one of them while being slidable at the other one. Wire  26  slidably extends through the overall length of stem  24  forming a loop along it and its free ends are conveyed externally through connector  29 . Clearly, by pulling one of the two ends from the outside, the opening and closure of clamp  27  can be controlled, as also shown in FIGS. 7 a  and  7   b.    
         [0029]    As shown in FIGS. 6 a, b, c , rear end section  21   c  of the device comprises a first sleeve  33  coaxially mounted on stem  24  and slidable thereon. Sleeve  33  has a flanged end one side of which is fixed to rear flange  22   b  of intermediate section  21   a , the other one being fixed to a bellow  31  coaxial thereto. A pair of arm  33   a ,  33   b  extend from sleeve  33  in a diametrically opposed and parallel relationship with respect to stem  24 . Arms  33   a ,  33   b  are arranged on a plane rotated of an angle of 90° with respect to the two jaw portions of first clamp  27  and support jaws  32   a  and  32   b  of second clamp  32 . Likewise first clamp  27 , second clamp  32  is formed by two diametrically opposed clamp portions and therefore clamps  27  and  32  are in a substantially crosswise arrangement with respect to the longitudinal axis of the device, as shown in FIG. 4.  
         [0030]    In particular, the pair of portions of jaw  0 . 32   a  are fixed to the free ends of arms  33   a  and  33   b , while the pair of portions of mobile jaw  32   b  are formed at the end of two further arms  34   a  and  34   b  extending at the outside of arms  33   a  and  33   b  and parallel thereto from a second sleeve  34  integral to bellow  31  and axially slidable on sleeve  33 . The sliding of arms  34   a, b  with respect to arms  33   a, b  is limited at one side by the abutment with fixed jaw  32   a  and at the other side by the mutual abutment between shoulders  35  and  36  formed on the respective sliding surfaces.  
         [0031]    Tubular connector  29  houses a plurality of pneumatic tubes communicating to a series of conduits formed in stem  24 . In particular, with reference to FIG. 3, conduits  37  and  38  are provided for creating a depression or feeding compressed air between jaws  27   a, b  of first clamp  27  and jaws  32   a, b  of second clamp  32 , to help engagement and, respectively, release of the surrounding wall portion P of the body cavity, and conduits  45  and  46  to suck or feed air from/to bellows  31  and  22 , thereby causing them to extend and respectively to retract. A conduit for feeding air to head  25  is also provided to blow air against the cavity wall during the forward motion. These conduits are all shown in FIG. 3 for sake of simplicity. Conduits  38  and  45  are helically arranged inside chamber  23 .  
         [0032]    The operating cycle of the endoscopic device according to the second embodiment of the invention is shown in FIGS. 8 a - 8   g . First, vacuum is created in correspondence of the jaws of second camp  32  to cause a surrounding wall portion P of the body cavity to collapse therebetween (FIG. 8 a ), then compressed air is entered in bellows  31  which in this way is elongated causing the closure of second clamp  32  and the grasping of wall portion P (FIG. 8 b ). Compressed air is entered in chamber  23  of bellows  22  which expands pushing front head  25  forward. In view of the connection through stem  24  front head  25  pull first clamp  27  forward (FIG. 8 c ) After having created a depression between the jaws of first clamp  27  to make the surrounding wall portion P to collapse therebetween, first clamp  27  is closed by traction of actuating wire  26  to grasp wall portion P (FIG. 8 d ). At this point second clamp  32  can be opened by sucking air from bellow  31 , to release the wall portion P held thereby (FIG. 8 e ). Once second clamp  32  is opened, it is made to advance with respect to first clamp  27  by sucking air from bellow  22 , which retracts (FIG. 8 f ). In these conditions, after second clamp  32  is held again to the body cavity wall, first clamp  27  is opened and the cycle repeated for a further advancement step.  
         [0033]    Opposed grip surfaces of jaws of first and second clamp  27  and  32  are formed with an annular groove and a corresponding step for engaging therewith to improve the grip of the wall portion of the body cavity.  
         [0034]    It will be appreciated that in the second embodiment of the invention clamps  27  and  32  alternately overtake each other during each advancement step of the device and the clamp that in turn is in the distal position is the gripping one, while the other one is free and is pulled forward. This prevents the body cavity wall, due to its easily yielding nature, from retracting into folds together with the device in the retraction step and extending in the next extension step without achieving any real forward motion of the device.  
         [0035]    From the foregoing it is clear that the endoscopic device according to the invention can migrate through a body cavity of tubular shape apart from the consistency of the walls and the friction that can be afforded by them, because it is able to grasp at the cavity wall before exerting its propulsive push. The increased patient&#39;s comfort and the reduction of manual handling made possible with the device of the invention could promote the possibility of mass screening the population for gasto-itnestinal aliments, in particular to carry out colonoscopy and rectosigmoidoscopy, this being a particularly important inspection, in so far as about 70% of the colon cancers are localized in the first tract or the colon. In addition to inspection and diagnosis, future integration of miniaturized endoscopic tools onboard the locomotive device would allow therapeutic procedures to be performed as well.  
         [0036]    Several variations may be brought to the above described endoscopic device. Front and rear end sections can be removably connected to the intermediate section so as to be easily replaced in case of damage, for example due to clogging by pollutants, or for maintenance. The wall of the intermediate section can be constituted by an elastically extensible smooth tube instead of a bellows. The device could be made with disposable plastic materials, provided that they are suitable for insertion in a body cavity.  
         [0037]    Even if in the present embodiments of the invention pneumatically actuated bellows means have been provided for controlling the extension and the retraction of the intermediate section and the opening and closing of the clamping means, it is clear that, as an alternative, any equivalent linear actuating means such as elastic means or minimotors, can be used. Likewise, compressed air distribution can be carried out in a different way from what has been illustrated, for example by using microvalves within the device, possibly controlled with shape memory alloy actuators.  
         [0038]    Further variations and/or modifications can be brought to the endoscopic device according to the present invention, without departing from the scope of the invention as set forth in the attached claims.