Abstract:
An endoscope, comprising an elongated tubular shaft for introducing into a body of a patient, the shaft having a longitudinal axis and a distal end, and further having an opening the distal end. A light guide is arranged along the shaft and has a light-emitting distal end, the light-emitting distal end being arranged in the area of the opening of the shaft in order to radiate light from the opening.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to an endoscope. 
     Without limiting its general application, the endoscope according to the invention is particularly suitable for tracheotomy. An endoscope used for this purpose is also referred to as a tracheoscope or bronchoscope. 
     In a tracheotomy procedure, when a patient whose normal breathing through the nose and mouth is impaired or no longer possible, an artificial route of respiration is established through the throat below the larynx. To do this, a trocar is used to create, from the outside, an incision through the throat and into the trachea, into which a tracheotomy cannula is later inserted through which the patient then breathes or can be ventilated. 
     A difficulty that arises in an operation of this kind lies in determining the exact position of the incision for the subsequent tracheotomy cannula. For this purpose, as has been described in document DE 695 27 958 T2; an endoscope is introduced through the patient&#39;s mouth and into the trachea, where the distal end of the shaft of the endoscope comes to lie just below the larynx. Arranged in the known endoscope there is a light guide whose distal end, from a distal opening of the endoscope shaft, radiates light in the direction of the anterior wall of the trachea. A spot of light is then visible on the skin of the front area of the throat, and the illuminated area of the trachea is also made visible. By moving the endoscope or light guide, the light spot can now be positioned in such a way that it comes to lie between two cricoid cartilages or tracheal rings of the trachea. The cricoid cartilages or tracheal rings stand out from the rest of the tracheal wall by virtue of a different intensity or coloration of the light spot. As soon as the light spot is correctly positioned, the aforementioned incision through the skin and into the trachea can now be made by means of a trocar with the aid of the light spot. 
     The known endoscope has a light guide which is continuously straight and whose light-emitting window is cut obliquely in relation to the longitudinal axis of the light guide. This results in an obtuse angle of radiation of the light relative to the longitudinal axis of the light guide. Since the light is not radiated strictly to form a point but instead in an areal manner, the oblique incidence of light on the tracheal wall has the effect that the visible light spot is “smudged”. To ensure a perpendicular incidence of the beam of light on the tracheal wall, the known endoscope has to be held obliquely relative to the longitudinal axis of the trachea, but the confined spaces in the region of the larynx and mouth through which the endoscope is introduced means this is not possible. If the light spot visible from outside is smudged, however, the incision into the trachea for the subsequently inserted tracheotomy cannula cannot be made with pinpoint precision. If this incision is not formed with pinpoint precision, the result of the tracheotomy may be compromised. 
     SUMMARY OF THE INVENTION 
     An object of the invention is therefore to develop an endoscope of the type mentioned at the outset in such a way that it allows an incision to be made into the trachea with pinpoint precision. 
     According to the invention, an endoscope is provided, comprising an elongated tubular shaft for introducing into a body of a patient, the shaft having a longitudinal axis and a distal end, and further having an opening at the distal end. A light guide is arranged along the shaft and has a light-emitting distal end, the light-emitting distal end being arranged in the area of the opening of the shaft in order to radiate light from the opening. The light-emitting distal end of the light guide is angled relative to the longitudinal axis of the shaft by an angle in a range of about 70° to about 110°. 
     The angled arrangement, according to the invention, of the light-emitting distal end of the light guide relative to the longitudinal axis of the shaft means that the light is also radiated at an angle in the range of about 70° to about 110° relative to the longitudinal direction of the shaft, so that, even without the shaft of the endoscope being positioned obliquely, it is possible to produce, on the tracheal wall and on the skin of the throat area, a smaller light spot than is obtained merely with an obliquely configured window at the distal end of the light guide. Thus, the endoscope shaft can be introduced advantageously in the longitudinal direction of the trachea and does not have to be angled relative to the trachea. In this way, the advantage of pinpoint precision of the incision into the trachea at the desired site is achieved. 
     In a preferred embodiment, a light-emitting window of the light-emitting end of the light guide extends approximately parallel to the longitudinal axis of the shaft when the light guide is oriented parallel to the longitudinal axis of the shaft. 
     With a light-emitting window extending parallel to the longitudinal axis of the shaft, the light spot produced on the tracheal wall and on the skin in the throat area becomes even smaller and the incision into the trachea can therefore be made with even greater precision, because the incidence of the light beam is at least approximately perpendicular to the skin. By contrast, in the case of an oblique light-emitting window, as in the known endoscope, there is an inevitable smudging and increase in size of the light spot, which makes an incision with pinpoint accuracy difficult. 
     In another preferred embodiment, the distal end of the light guide is angled relative to the longitudinal axis of the shaft by an angle in a range of about 80° to about 180°, and in yet another preferred embodiment the light-emitting distal end of the light guide is angled relative to the longitudinal axis of the shaft by an angle of about 90°. 
     Especially by combination of a distal end of the light guide, set at a right angle, with a window which extends parallel to the longitudinal axis of the shaft and from which the light emerges, it is possible to produce a particularly small and sharp light spot on the tracheal wall and on the skin in the throat area, with the result that the formation of the incision can be effected with very great accuracy. 
     According to another aspect of the invention, an endoscope is provided, comprising an elongated tubular shaft for introducing into a body of a patient, the shaft having a longitudinal axis and a distal end, and further having an opening at the distal end. The opening of the shaft extends obliquely relative to the longitudinal axis of the shaft. A light guide is arranged along the shaft and has a light-emitting distal end, the light-emitting distal end being arranged in the area of the opening of the shaft in order to radiate light from the opening. 
     Preferably, an edge of the opening forms, with the longitudinal axis of the shaft, an angle in a range of about 10° to about 40°. 
     The surface area of the opening is increased by this strongly oblique positioning of the opening of the shaft relative to the longitudinal axis of the shaft. The increase in the surface area of the opening now has the advantage that the rear wall of the shaft is likewise increased in size in the area of the opening, and this results in an enlarged protective surface which, during insertion of the trocar into the trachea, advantageously avoids the trocar drilling through or damaging the opposite wall of the trachea. Also in the subsequent maneuvers involved in fitting the tracheotomy cannula in which instruments are inserted through the incision into the trachea, the rear wall of the shaft, increased in size by the aforementioned measure in the area of the opening, advantageously serves as protection against damage to the posterior wall of the trachea. 
     In this context, it is preferable and advantageous if the light-emitting distal end of the light guide is arranged or comes to lie in a proximal area of the opening when the light guide is inserted into the shaft. 
     It is particularly preferable if the edge of the opening forms, with the longitudinal axis of the shaft, an angle in a range of about 15° to about 25°. 
     In another preferred embodiment, the light guide is arranged or can be arranged in the interior of the shaft, and the light guide extends near a shaft wall which is directed away from the opening. 
     This measure has the advantage that the light guide as a whole can be made rigid and, despite the angled position of the light-emitting distal end, the diameter of the shaft of the endoscope is not greater than in conventional endoscopes of this kind. 
     In another preferred embodiment, the distal end of the light guide has such a length that it does not protrude from the opening. 
     The advantage of this is that, if the endoscope is introduced into the patient&#39;s body already together with the light guide, the light-emitting distal end of the light guide does not form an obstacle during the advance of the endoscope. 
     In another preferred embodiment, the light guide can be withdrawn from the shaft. 
     This measure has the advantage of improved cleaning of the endoscope, since the light guide, after withdrawal from the shaft of the endoscope, can be more thoroughly cleaned than if it were to be left in the shaft of the endoscope. Moreover, in some cases the light guide is not required for the whole operation, so that, after removal of the light guide, the shaft of the endoscope can be used for the insertion of other instruments, or of a traction wire used in the tracheotomy procedure, without the light guide forming an obstacle. 
     In another preferred embodiment, a coupling is present at the proximal end of the light guide and at the proximal end of the shaft for the purpose of securing the light guide on the shaft in a predetermined position of rotation of the light guide relative to the shaft. 
     In conjunction with the angled positioning of the light-emitting distal end of the light guide, this measure has the advantage that the light guide is always connected to the shaft in the correct position of rotation in relation to the opening of the shaft, such that the light-emitting distal end of the light guide faces toward the opening. 
     Further advantages and features will become evident from the following description and from the attached drawing. 
     It will be appreciated that the aforementioned features and the features still to be explained below can be used not only in the respectively cited combination, but also in other combinations or alone, without departing from the scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An illustrative embodiment of the invention is described in more detail below with reference to the drawings, in which: 
         FIG. 1  shows an endoscope in a side view and partially in longitudinal section; 
         FIG. 2  shows a shaft of the endoscope from  FIG. 1  in a side view, with associated attachment parts at the proximal end of the shaft; 
         FIG. 3  shows a side view of a light guide of the endoscope from  FIG. 1  on its own, with associated attachment parts at the proximal end of the light guide, the light guide in  FIG. 3  being shown enlarged by comparison with  FIG. 1 ; 
         FIG. 4  shows a side view of the endoscope from  FIG. 1 , the light guide having been inserted into the shaft of the endoscope; and 
         FIGS. 5   a ) to  c ) show schematic representations of three method steps involved in the use of the endoscope from  FIG. 1  in the context of a tracheotomy. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In  FIGS. 1 and 4 , an endoscope for tracheotomy is provided with the general reference number  10 . It will be appreciated that the endoscope  10  can also be used in other medical disciplines. 
     Components of the endoscope  10  are shown separately in  FIGS. 2 and 3 . 
     The endoscope  10  comprises a shaft  14  which has a longitudinal axis  12  and which, because of its length, is shown interrupted in the figures. The shaft  14  is in particular rigid. The longitudinal axis  12  is to be understood as the direction of longitudinal exension of the shaft  14 . 
     At a proximal end  16 , the shaft  14  has a coupling part  18  which will be described later and which is used to secure a light guide of the endoscope  10 ; a connector tube  20  which extends obliquely and is used for the insertion of auxiliary instruments, wires and the like; and a connector tube  22  which can be used, for example, for attachment of a ventilation line in the event of the endoscope  10  being used in a tracheotomy.  FIG. 2 , which shows the shaft  14  separately, also indicates a channel  13  arranged on the outside of the shaft  14  and with a connector  15  for attachment of a line (not shown). The outer channel  13 , which has been left out in  FIGS. 1 and 4 , is used for respiratory gas monitoring. 
     At the distal end, the shaft  14  has an opening  24  at which the shaft  14  opens out. An edge  26  of the opening  24  extends obliquely in relation to the longitudinal axis  12  of the shaft  14  and forms, with the longitudinal axis  12  of the shaft  14 , an angle α in the range of about 10° to about 40°; in the present illustrative embodiment about 20°. 
     A rear wall  28  of the shaft  14 , directed away from the opening  24 , is closed and extends over more than approximately half the circumference of the shaft  14 . The central surface line of the rear wall  28  as seen in  FIG. 1  is slightly oblique in relation to the rest of the wall of the shaft  14  and in relation to the longitudinal axis  12  of the shaft  14  by an angle β, specifically pointing outward by a few degrees. 
     The endoscope  10  also comprises a light guide  30 , which is shown separately and on an enlarged scale in  FIG. 3 . 
     The light guide  30  in  FIG. 1  is arranged along the shaft  14 , specifically in the interior of the shaft  14 , near a wall  32  of the shaft  14  directed away from the opening  24 , and parallel to the longitudinal axis of the shaft  14 . 
     The light guide  30  is substantially rigid and has, for example, a metal sleeve in which optical fibers or another light-conducting medium (not shown) are contained. 
     At a proximal end  34 , the light guide  30  has a coupling part  36  which cooperates with the coupling part  18  of the shaft  14  to secure the light guide  30  on the shaft  14 . The coupling part  18  and the coupling part  36  together preferably form a plug coupling, so that when the light guide  30 , which is withdrawable from the shaft  14 , is reinserted into the shaft  14 , it can be secured on the shaft  14  by simply plugging together the coupling parts  18  and  36 . The plug coupling is designed such that the light guide  30  can be coupled to the shaft  14  only in a specific position of rotation about its own longitudinal axis. 
     Moreover, the light guide  30  has, at the proximal end, a connector  38  for attachment of a fiber optic cable (not shown) via which light from an external light source can then be fed to the light guide  30 . 
     As can be seen from  FIG. 1 , a light-emitting distal end  40  of the light guide  30  is angled relative to the longitudinal axis  12  of the shaft  14 , specifically by an angle in the range of about 70° to about 110°. In the preferred illustrative embodiment shown, the light-emitting distal end  40  of the light guide  30  is angled by 90° relative to the longitudinal axis  12  of the shaft  14 . A light-emitting window  42  of the light-emitting distal end  40  extends in particular approximately parallel to the longitudinal axis  12  of the shaft  14 . 
     As has already been mentioned, the light guide  30  can be withdrawn from the shaft  14 .  FIG. 4  shows the reverse procedure, in which the light guide  30  has just been inserted into the shaft  14 . The light guide  30  is inserted into the shaft  14  until the coupling parts  18  (shaft  14 ) and  36  (light guide  30 ) are in engagement with one another, as is shown in  FIG. 1 . 
       FIGS. 5   a ) to  c ) are schematic representations showing the use of the endoscope  10  in the context of a tracheotomy. 
     Reference number  44  designates a patient&#39;s trachea, shown in a stylized form. 
     A posterior wall  46  of the trachea, directed toward the back of the patient&#39;s throat, and an anterior wall  48  of the trachea, directed toward the larynx, are shown in a stylized form in the drawing. Cricoid cartilages or tracheal rings  50 ,  52 ,  54 , etc., are situated in the tracheal wall  46 ,  48 . 
     In a first method step, shown in  FIG. 5   a ), the endoscope  10  with the shaft  14  is introduced through the mouth and throat into the trachea  44 , and specifically to the extent that the opening  24  of the shaft  14  comes to lie more or less level with the first cricoid cartilages  50  to  54  and points in the direction of the anterior wall  48  of the trachea. In cases where the light guide  30  has not been fitted into the shaft  40  upon insertion of the endoscope  10 , the light guide  30  is introduced into the shaft  14  in the direction of the arrow  56 , specifically until the light-emitting distal end, which, as has been described above, is angled relative to the longitudinal axis  12  of the shaft  14  by about 90°, comes to lie level with the opening  24  and the window  42  points in the direction of the opening  24 . This is shown in  FIG. 5   b ). The exact position of the light-emitting distal end  40  of the light guide  30  is shown in  FIG. 1 , and it will be noted that the light-emitting window  42  is situated in the proximal area of the opening  24  in the final position of the light guide  30  in the shaft  14 . 
     If the light guide  30  is now supplied with light, the light emerges from the window  42  of the light guide  30  and produces a preferably sharply defined light spot  58  of small size on the anterior wall  48  of the trachea, which light spot shows through the patient&#39;s skin and can thus be seen from outside. The size of the light spot  58  is shown purely schematically in  FIG. 5   b ), and in particular said light spot  58  can also cover the first cricoid cartilage  50  and the second cricoid cartilage  52 , such that these are discernible by way of the light spot, on account of the different intensity of these light spot regions occasioned by the cricoid cartilages  50  and  52 . As is shown in  FIG. 5   b ), the light propagation direction  60  is substantially perpendicular to the longitudinal axis  12  of the shaft  14  of the endoscope  10 . 
     According to  FIG. 5   c ), the sharply defined light spot  58  can now be used, with the aid of a trocar  62  placed on the light spot  58  showing through the patient&#39;s skin, to make a precisely targeted incision through the skin and then through the anterior wall  48  of the trachea, without damaging the cricoid cartilages  50 ,  52 ,  54 , etc. 
     By virtue of the oblique formation of the opening  24  that runs toward a point, and by virtue of the resulting large surface area of the rear wall  28  of the shaft  14  in the region of the opening  24 , the trocar  62 , when advanced farther in the direction of an arrow  64 , strikes the rear wall  28 , and the rear wall  28  thus reliably ensures that the posterior wall  46  of the trachea is not also pierced. 
       FIG. 5   c ) also shows clearly that, even when the trocar  62  is inserted obliquely, as is indicated by broken lines, the trocar  62  is still effectively stopped by the rear wall  28  of the opening  24  and cannot damage the posterior wall  46  of the trachea. 
     In subsequent method steps too, in which further instruments are introduced through the incision created with the trocar  62 , the rear wall  28  safely protects the posterior wall  46  of the trachea from injury.