Abstract:
A shaft is provided for a flexible endoscope. The shaft has a tubular mantle whose outer surface contacts a body tissue of a patient during use of said endoscope. The outer surface of said shaft is microscopically roughened, for example by sand blasting.

Description:
CROSS REFERENCE OF PENDING APPLICATION  
       [0001]    This is a continuation of pending international application PCT/EP00/04761 filed on May 25, 2000 which designates the U.S. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to a shaft for a flexible endoscope comprising a tubular mantle whose outer surface comes into contact with body tissue of a patient during use of the endoscope. Furthermore, the invention relates to a flexible endoscope having such a shaft.  
           [0003]    Such flexible endoscopes with a corresponding shaft are known for example having the designation Fiberskop in the catalogue “Endoskopie in der Tiermedizin”, 5th edition, 1/95 from Karl Storz GmbH &amp; Co., Tuttlingen, Germany. In addition, fiberscopes, i.e. flexible endoscopes, are also used for various purposes in human medicine, e.g. for diagnosing respiratory passages.  
           [0004]    Flexible endoscopes distinguish from rigid endoscopes in that the shaft of a flexible endoscope has a flexibility such that it can take on a bent, strongly curved or even a loop-shaped form. To achieve the necessary flexibility, the shaft of a flexible endoscope normally consists of a tubular, flexible mantle, which houses the components necessary for the endoscope, such as an image transmission guide, an optical guide, an instrument channel and actuator cables. The tubular mantle normally consists of a synthetic material which is sealed at its outer side for example with one or more layers of polyurethane.  
           [0005]    The length of the endoscope shaft, especially in veterinary medicine, can be up to 150 cm or more. In the field of human medicine, the length of the flexible endoscope shaft is normally between 15 cm and 50 cm. The outer surface of the shaft should have good glide properties as far as possible because the flexible shaft must be inserted over most of its length into an often narrow body cavity when treating a patient or an animal. This is achieved in conventional flexible endoscopes in that the endoscopes are provided with a cover lacquer which is as smooth as possible and also consists of polyurethane.  
           [0006]    In practice, however, the glide properties of known flexible endoscope shafts have proven to be insufficient in some cases, especially with increasing lengths. In these cases, an additional glide material, for example in the form of a gel, must be used in order to insert the shaft into the body cavity as easily as possible and with as little pain as possible for the patient or animal. The glide properties of the endoscope shaft are basically improved by the use of a glide material. However, a need still exists for optimising the glide properties of the flexible endoscope shafts as far as possible to be able to treat a patient or an animal as simply or as easily as possible. In the optimal situation, the use of an additional glide material is then no longer needed.  
           [0007]    The object of the present invention is therefore to provide a shaft of the mentioned type whose glide properties are improved compared to previously known endoscope shafts. In addition, an object of the present invention is to provide a corresponding flexible endosocope.  
         SUMMARY OF THE INVENTION  
         [0008]    The object is achieved in that the outer surface of the shaft is microscopically roughened. The flexible endoscope according to the present invention possesses a corresponding shaft.  
           [0009]    Roughened microscopically will be understood in that the outer surface of the shaft is roughened to an extent which is not recognizable by the naked eye or by simple touching. Even so, the outer surface of the shaft according to the invention is uniformly rough compared to the known conventional endoscope shafts. The roughening can preferably be achieved by sand blasting, which will be discussed in more detail below. Basically however, it is also possible to produce microscopically rough surfaces in other ways.  
           [0010]    It has been found completely surprisingly that a microscopically roughened surface when in contact with body tissue has distinctly better glide properties than a completely smooth surface, as has been achieved conventionally using smooth lacquer layers. The rough configuration of the outer surface represents a sharp contrast to all previous measures for improving glide properties, which have always had the intention of making the outer surface as smooth as possible. A possible explanation for the surprising phenomenon is that an outer surface results from roughening which has numerous crater-like depressions. Thus the total contact surface of the outer surface with the surrounding body tissue is smaller than that when the outer surface is smooth. Independent of this attempted explanation, the mentioned feature offers a very simple and exceptionally effective possibility to improve the glide properties of flexible endoscope shafts. There is no need to use a glide material when inserting the shaft into a body. Glide materials bear the risk of allergic reactions in the body, which risk is now excluded.  
           [0011]    In an embodiment, the outer surface is roughened by sand blasting. The feature has the advantage that the roughening takes place with a simple measure, which is controllable with conventional technologies. This feature can represent the last finishing step in the manufacture of the shaft without substantial effect on the previously performed manufacturing steps. The mentioned feature thus has the advantage that the improvement of the glide properties is particularly simple and inexpensive from the manufacturing viewpoint. A further advantage is that existing conventional endoscope shafts can be subsequently treated, so that a subsequent improvement of the glide properties of existing or even of already used endoscope shafts is possible.  
           [0012]    In a further embodiment of the above-mentioned feature, the outer surface is roughened by sand blasting with grains having edges. Basically it is also known to roughen surfaces by sand blasting with bead-like grains, i.e. not having edges. Investigations have however shown that the improvement of the glide properties is predominant and particularly rapid when using grains having edges.  
           [0013]    In a further embodiment of the present invention, the outer surface is roughened to have a roughness which is achievable by sand blasting with corundum 0.05 to 0.5 mm. The numbers 0.05 to 0.5 mm represent the grain size in the known manner for the corundum grains used in sand blasting. The use of other grain sizes or also grinding materials other than corundum is however generally not excluded in this embodiment of the invention.  
           [0014]    Decisive is that a roughness of the outer surface is achieved which corresponds to that which is achievable with the aid of the mentioned feature. Namely, it has been shown that such a roughness represents a considerable improvement of the glide properties compared to previously known endoscope shafts. On the other hand, the outer surface of the endoscope shafts experience no measurable degradation with respect to sterilizability and thus the repeated use in the treatment of patients or animals. The mentioned feature is a result of empirical tests and represents an excellent improvement of the glide properties compared to previously employed flexible endoscope shafts. Very good results could also be achieved by sand blasting with glass beads 40 to 70 μm or 70 to 110 μm.  
           [0015]    In a further embodiment, the outer surface is roughened by etching. The feature has the advantage that the roughening can take place very uniformly in simple manner. In the simplest case, the previously smooth endoscope shaft is simply placed in a suitable etching bath for a certain time. The outer surface is chemically roughened. The necessary etching agent depends on the material used in forming the outer surface. Suitable etching agents are known per se in the prior art.  
           [0016]    In a further embodiment, the outer surface is roughened by abrasion. In contrast to sand blasting, abrasion will be understood as a mechanical roughening of the outer surface, which can be performed with a grinding disc, with sand paper or with similar abrasive means connected to a body. The feature has the advantage that the roughening can be locally specific and differentiated, where different locations on the endoscope shaft can be provided with differing degrees of roughness. For example, differing grain coarseness can be used for different regions of the shaft to generate different roughness at different locations and therefore varying glide properties.  
           [0017]    In a further embodiment of the present invention, the outer surface consists of a material which is initially glossy and which is then roughened to an extent that it appears dull. This feature is also the result of empirical tests. Tubular mantles for endoscope shafts were employed as known from the above-mentioned catalogue from Karl Storz GmbH &amp; Co., Tuttlingen, Germany. With these known endoscope shafts, the outer surface is formed by a transparent cover lacquer of polyurethane which appears glossy after being hardened. To improve the glide properties, these outer surfaces are preferably roughened to the extent that they appear dull.  
           [0018]    The feature has the advantage that it represents a simple and easily controllable criterion for manufacturing endoscope shafts according to the present invention. The production of the present endoscope shafts is therefore possible without greatly interfering with the previously performed manufacturing steps. On the whole, considerable improvements in the glide properties can be achieved with the mentioned feature in simple manner.  
           [0019]    In a further embodiment of the present invention, the tubular mantle comprises at least one base layer and a cover layer arranged thereon, where only the cover layer is roughened. The feature has the advantage that any harm to the inner mantle region of the endoscope shaft is avoided. It is also ensured that a frequent sterilization of the components of the endoscope lying within the endoscope shaft is not impaired.  
           [0020]    According to a further embodiment of the present invention, the average roughness value R a  of the roughened surface lies in the range of 0.1 to 1.6 μm. The feature has the advantage that surfaces with this average roughness value show particularly good glide properties along the tissue.  
           [0021]    It will be understood that the above-mentioned features and those to be discussed below are applicable not only in the given combinations but also in other combinations or taken alone without departing from the scope of the present invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    Embodiments of the invention are illustrated in the drawings and will be discussed in more detail below.  
         [0023]    [0023]FIG. 1 shows a perspective view of a flexible endoscope according to the present invention.  
         [0024]    [0024]FIG. 2 shows a cross-section through the shaft of the endoscope according to the present invention taken along the line II-II in FIG. 1.  
         [0025]    [0025]FIG. 3 shows a greatly enlarged illustration of the tubular mantle of the flexible endoscope of FIG. 2. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0026]    A flexible endoscope according to the present invention is shown in FIG. 1 and indicated with the numeral  10 . The flexible endoscope  10  comprises a head portion indicated with the numeral  12 . An ocular  14  extends from the proximal end of the head portion  12 . A connector  16  extending to the side serves to connect a train  18  of lines, which contain lines for illumination, flushing, insufflation, suctioning or the like. A further connector  20  extending approximately in the direction of the ocular  14  is provided, through which instruments can be inserted into the endoscope or the head portion  12 , for example pincers, slings or the like.  
         [0027]    Two hand wheels  22 ,  23  are arranged at the side of the head portion  12 , with which the view direction of the endoscope can be adjusted as described below. In addition, switches  24 ,  25 ,  26  are arranged in the region of the head portion  12 , through which various functions can be controlled, for example, suctioning, flushing or the like, which is known per se in the construction of flexible endoscopes.  
         [0028]    An elongated flexible shaft  30  extends from the head portion  12 , which in the present embodiment has a length of about  1  m. The shaft  30  is made of a flexible synthetic material, which enables a deflecting and bending of the shaft  30  as shown in FIG. 1. An end section  32  has an increased bendability compared to the shaft  30 , where the end section  32  can be additionally bent by more than 180° in semi-circular manner as can be taken from FIG. 1. The end section  32  can be rotated out of the position indicated by the solid lines in FIG. 1 by more than 180° while the shaft  30  remains unchanged in its orientation. This is performed by a cable mechanism which extends from an end piece  34  to the hand wheels  22 ,  23 . A rotated position of the end section  32  is illustrated in FIG. 1 by the broken lines. This movability of the end section  32  achieved in this manner is known per se for flexible endoscopes and allows an adjustment of the view direction of the endoscope.  
         [0029]    In the cross-section view of FIG. 2, the interior configuration of the shaft  30  of -the endoscope  10  is shown, which is also known per se. The shaft  30  comprises a tubular mantle  36  with an image transmission guide  38 , an optical guide  40 , an instrument channel  42  and cables  44 ,  46  located in its interior. The cables  44 ,  46  are connected to the hand wheels  22 ,  23  and enable the described movement of the end section  32 .  
         [0030]    A sand blasting of the outer surface  50  is indicated schematically with the numeral  48 . The outer surface  50  is microscopically roughened by the sand blasting  48 . The glide properties of the outer surface  50  of the mantle  36  and therefore the glide properties of the shaft  30  are improved in this manner. Preferably, sand blasting  48  for this purpose takes place with grains  49  having edges.  
         [0031]    In a particularly preferred embodiment, the outer surface  50  of the mantle  36  is roughened by sand blasting  48  with corundum 0.12 to 0.25 mm. The numbers 0.12 to 0.25 mm as mentioned above relate to the grain size of the employed grains  49 . Such grain sizes are well known in the field of sand blasting. In an alternative embodiment, the outer surface  50  of the mantle  36  is roughened by sand blasting with glass beads 40 to 70 μm or 70 to 110 μm.  
         [0032]    Contrary to the schematic illustration in FIG. 2, the sand blasting  48  of the outer surface  50  preferably takes place at a time when the image transmission guide  38 , the optical guide  40 , the instrument channel  42  and the cables  44 ,  46  are not yet assembled in the shaft  30 .  
         [0033]    In an alternative embodiment of the present invention, the outer surface  50  is roughened by etching in a suitable etching bath or by abrasion with a suitable grinding body, for example a grinding disc.  
         [0034]    The roughness characteristics (according to the German industry standard DIN 4768 T1; 8.74) of roughened shafts of fiberscopes of the applicant are listed in the following Table 1, which were roughened with different roughening means.  
                                                       TABLE 1                           Roughness characteristics (DIN 4768 T1; 8.74)                Shaft 1   Shaft 2   Shaft 3                            R a     0.42 μm    0.70 μm   0.9 μm           R z     2.5 μm   4.20 μm   5.30 μm            R max     3.3 μm    5.2 μm   6.5 μm                                                                                              
 
         [0035]    As can be taken from the enlarged representation of FIG. 3, the outer surface  50  of the mantle  36  is roughened by sand blasting  48 . In addition, this enlarged view shows that the mantle  36  comprises a first base layer  52  consisting of a flexible synthetic material. This first base layer  52  forms the load-carrying inner region of the mantle  36 . A second base layer  54  seals the first base layer  52  on the outside. The second base layer  52  in the present embodiment consists of a soft polyurethane.  
         [0036]    A preferred embodiment, not shown here for reasons of clarity, includes a second base layer  54  of three individual polyurethane layers, which decrease in hardness from the inside of the mantle  36  to the outside. A cover layer  56  is applied to the outside of the outermost base layer  54 . The cover layer  56  consists of a transparent cover lacquer, which after hardening initially forms a very smooth, glossy surface  50 . This surface  50  is subsequently roughened microscopically by the sand blasting  48  or by the alternative possibilities indicated in FIGS. 2 and 3.  
         [0037]    In a preferred embodiment of the present invention, the outer surface  50  of the mantle  36  is roughened to the extent that the outer surface  50  appears to be dull. On the microscopic level, this leads to the fact that the outer surface  50  contains crater-like depressions  58 .  
         [0038]    The surface of a body tissue is indicated schematically with the numeral  60 , which comes into contact with the outer surface  50  when using the present endoscope  10 . As illustrated, the roughening of the outer surface  50  has the consequence that the body tissue  60  no longer comes into contact with the crater-like depressions  58 , but only with the plateaux lying therebetween. In this manner, the total contact surface is reduced when compared to the conditions with the previously known endoscope shafts  30 . Consequently, the shaft  30  of the endoscope  10  of the present invention possesses improved glide properties.  
         [0039]    The pressure and the duration for applying sand blasting  48  to the outer surface  50  of the mantle  36  is preferably determined empirically, namely such that the previously glossy surface  50  of the cover layer  56  appears to be uniformly dull after sand blasting  48 .