Abstract:
A surgical implement for forming an opening in the skin of a patient comprises two bodies: a first for application to one side of the skin and a second, having an incision element, for application to the other side of the skin to co-operate with the first body. The opening in the skin is formed simply and safely by placing the first and second bodies either side of the skin and moving the incision element.

Description:
This is a continuation of PCT application No. PCTIGB98/01044, filed Apr. 9, 1998, the entire content of which is hereby incorporated by reference in this application. 
    
    
     The invention concerns a surgical implement for forming an opening in the skin of a patient, in particular for use in procedures involving the introduction of drainage tubing into body cavities. 
     BACKGROUND OF THE INVENTION 
     Surgical drains are routinely inserted into body cavities during certain surgical operations in order to allow fluid communication between the interior and the exterior. To avoid wound complications it is common practice not to route such drains via the primary surgical incision, but instead through a different part of the body wall by way of a smaller secondary incision. Introduction of the surgical drain involves passage of a tube from the body cavity (such as the abdomen or the thorax) through the body wall and, as skin is generally the most resistant tissue to be traversed, the conventional method is to employ an appropriately sharp metal introducer passed from the interior to the exterior, whilst the surgeon&#39;s free hand is used to provide counterpressure on the outside of the skin. An example of such an instrument is disclosed in U.S. Pat. No. 4, 716,901. Whilst quick and simple, there are a number of inherent risks with this procedure. Firstly, the introduction of a sharp instrument into a body cavity threatens injury by laceration or perforation to the patient&#39;s viscera. Secondly, because of the necessary proximity of the surgeon&#39;s hand to the point of exit of the sharp introducer, the surgeon is exposed to a significant risk of self injury, with the result of both physical trauma and, more importantly, ‘drainstick’ injury with the attendant risk of transmission of serious infective disease such as HIV and Hepatitis B. 
     Once the sharp introducer has passed through the skin the drain, which is conventionally a simple flexible latex tube attached to the rear end of the introducer, is pulled through the body wall opening. The introducer is then cut from the tube and the tube is sutured into place to prevent it being inadvertently pulled out of the body. This is generally done by stitching a suture loop to the skin, and then looping sutures around the tubing for a short distance from the skin exit point. 
     FIG. 1 illustrates schematically a part of the above-described conventional procedure, with the introducer  10  (attached to drain tubing  11 ) in the process of being pushed through the body wall  12  from the interior to the exterior, whilst the fingers  1 , of the surgeon&#39;s free hand are shown applying a counterpressure to the tented outer surface of the skin. 
     DE-A-3919740 and U.S. Pat. No. 5,152,749 disclose devices for inserting a catheter into the bladder in which a hollow sheath element carrying a sharp incision element is introduced into the bladder via the urethra, and the incision element is moved relative to the sheath to cut an opening through the wall of the bladder and through to the exterior. A catheter introducer is then attached to the incision element and the proximal end of incision element is pulled to draw the catheter into the bladder from the exterior. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a surgical implement for forming an opening in the skin of a patient which overcomes at least some of the drawbacks of conventional procedures. To this end, the invention provides a surgical implement for forming an opening in the skin of a patient comprising a first body having a distal end for application to one side of the skin and a second body for application to the other side of the skin to co-operate with the first body, the second body having: a sharp skin incision element moveably mounted thereto, a hollow form adapted to receive and locate the distal end of the first body, and means for moving said incision element relative to said second body. According to an alternative aspect of the invention, there is provided a surgical implement for forming an opening in the skin of a patient comprising a first body for application to one side of the skin; a second body having a sharp skin incision element moveably mounted thereto and means for causing movement of said incision element; whereby in use the first body can be applied to one side of the skin to cause tenting of the skin in a direction towards the other side of the skin and the second body can be applied to the other side of the skin to co-operate with the first body via the skin, while protecting the surrounding skin. 
     Preferably, the distal end of the first body is of blunt form to minimise damage to the one side of the skin. Said first body distal end may be provided with a recess, such that said movement of the incision element carries the element into said recess. 
     Use of the invention reduces the risk of harm to both the patient and to medical staff in making an incision in the wall of a body cavity, for example when introducing a drain tube to the body cavity. For such an operation, the surgical implement of the invention may include a surgical drain tube attached or attachable to the proximal end of said first body. 
     In a preferred form, said second body is of a generally tapering form, tapering from a distal portion for contacting the skin to a proximal portion to which said incision element is mounted. An opening may be provided in the proximal portion of said second body, providing access to the hollow interior of the second body, and the incision element may be arranged to travel through said opening between a first position, when it is held outside the opening, and a second position, when it is positioned within the hollow interior of the said second body. 
     When the surgical implement is to be used in respect of the introduction of a surgical drain, said opening can be dimensioned to allow passage therethrough of said first body. 
     Preferably, the incision element is supported by at least two wall sections projecting from the exterior of said second body, such that manipulation of said wall sections causes the incision element to travel between said first position and said second position. 
     The incision element may be arranged to be detachable from said second body on reaching said second position, and to this end a preferred embodiment is provided with an incision element mounted to said second body by way of at least one frangible element which breaks when the incision element is in said second position. 
     Preferably, the incision element depends from at least two substantially planar wings which are connected to the said wall sections and which, when the incision element is in its first position, are orientated obliquely to the incision element travel direction, such that an urging together of said wall sections will cause the incision element to travel towards said second position. 
     Said second body may be provided with opposed barb elements, and preferably said barb elements are provided on said wall sections to allow securement of a surgical drain tube passed through said opening in the distal portion of said second body. 
     Additionally or alternatively, said second body is provided with suture points to assist in its securement to said other side of the skin during surgical procedure. 
     For drain tube introduction the invention may take the form of a surgical kit comprising at least one surgical implement according to the invention, the kit including a range of said first bodies and a range of said second bodies, the bodies in each range differing from one another in at least one characteristic. 
     According to a further aspect of the invention, there is provided a method of forming an opening in the skin of a patient. said method comprising: 
     applying a distal end of a first body to one side of the skin; 
     applying a second body to the other side of the skin, the second body having a hollow form adapted to receive and locate the distal end of the first body via the skin while protecting the surrounding skin area, the second body having a sharp skin incision element moveably mounted thereto; and 
     bringing the first and the second body into mutual co-operation respectively on different sides of the skin and moving said incision element to puncture the skin. 
     Preferably, the method includes the step, after puncturing the skin, of passing said first body through said second body, and then passing a surgical drain tube through the skin incision and through said second body. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described more fully by way of non-limiting embodiments with reference to the accompanying drawing, in which: 
     FIG. 1 illustrates the prior art procedure for forming an opening in the skin of a patient for the introduction of a drainage tube into a body cavity; 
     FIG. 2 illustrates an introducer of a surgical implement according to the present invention; 
     FIG. 3 illustrates in sectional view a skin cap device of the surgical implement according to the invention, for use with the introducer of FIG. 2; 
     FIG. 4 shows a plan view of the skin cap device of FIG. 3; 
     FIG. 5 shows a sectional view of the surgical implement in place and illustrates an operational procedure according to the invention; and 
     FIG. 6 shows in section the surgical implement in place once a drain tube has been pushed out through the opening in the skin and through the skin cap device. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The surgical implement of the invention comprises two mutually cooperating parts, a first body and a second body, respectively an introducer and a skin cap device. 
     The introducer of FIG. 2 comprises an elongated cylindrical body  20 , circular in cross section, tapering towards a blunt distal nose  21 . The proximal end  22  is attached or attachable to a length of conventional drain tubing  23 , whilst at its distal nose the introducer has a deep recess  24  in the form of an inverted cone. As will be explained further below, the introducer is not intended to pierce the patient&#39;s skin, but simply to be pushed firmly against the inside of the body wall in order to tent the skin outwardly. There is therefore no requirement that the introducer is made of metal, and it can instead be realised in, for example, a stiff plastic material or latex. 
     The second part of the surgical implement, the skin cap device (FIG.  3 ), comprises a generally conical body  30  with an annular base flange  31 , near the apex of which is attached a central blade-mounting means  32 . The blade-mounting means consists of two upwardly projecting lateral opposed walls  33 , which are generally curved towards one another when seen in plan view to surround the open apex of the conical body  30 . From the central region of the upper edges of the two opposed walls are attached two downwardly and inwardly projecting planar wings  34  which meet and connect centrally and which support a downwardly-directed sharp disposable blade  35 , which is so sized as to fit within the apical aperture of the conical body  30 . The connections  36  between the two walls  33  and the conical body  30  and those  37  between the two walls and the wings  34  are formed as resilient hinges, which may be conveniently realised by moulding these items in a single piece from a plastics material, the inherent flexibility of the material providing the required hinges. The connection between the two planar wings  34  is also formed as a resilient hinge. The connections  37  between the two walls  33  and the wings  34  are moreover designed to be frangible under a certain force, as will be described below, and this characteristic may also be provided by an appropriate design in plastics material. On the inside faces of the two opposed walls  33  are arranged sets of downwardly and inwardly projecting barb wings  38 , which extend inwardly to leave a gap therebetween approximately the same width as the diameter of the open apex of the conical body. These barb wings  36  serve to restrain the movement of the drain tube once it is in place and their function is further explained below with reference to the operation of the surgical implement. 
     The skin cap device is shown in plan view in FIG. 4, and the shaping and relative dimensions of the various component parts described above can be seen from this drawing. On opposed sides of the outer edge of the base flange  31  are provided two projecting lugs  39  each with a suture port  40  to enable the skin cap device to be sutured in place to the patient&#39;s skin. 
     The surgical procedure will now be described with reference to FIGS. 5 and 6 to illustrate the use of the surgical implement of the invention. 
     Firstly, the desired site for exit of the drain is selected and prepared by application of an topical antiseptic solution. Using the non-dominant hand, the surgeon then places the skin cap device over the desired exit site, ensuring it is placed with the blade  35  orientated in the line of election, to ensure an incision in that same line of election and therefore to minimise subsequent scarring. To aid in the correct positioning of the skin cap device, it is preferably manufactured from a transparent material and may carry marking to clearly indicate orientation. The introducer is then manipulated by the surgeon&#39;s dominant hand from within the body cavity towards the body wall on the inside of the exit site. 
     The blunt distal nose  21  of the introducer is then used to tent the skin outwardly within the hollow interior of the conical body  30 , whilst the surgeon&#39;s fingers hold the skin cap device firmly against the skin around its base flange  31 . The skin is therefore pushed up towards the apical hole of the conical body, sandwiched between the introducer and the inside periphery of the top portion of the conical body, as shown in FIG.  5 . 
     With the surgeon&#39;s fingers still held against the base flange  31  the two walls  33  are squeezed together. The hinge connections  36  and  37  therefore provide that the wings  34  and the dependent blade  35  are driven directly downwards, the blade thus incising through the skin at the precise desired location. The blade having passed through the skin and underlying tissue layers is then received in the recess  24  of the distal nose  21  of the introducer, so minimising any risk-to the surrounding tissue. The surgeon then releases the squeezing action on the two walls  33  and, continuing to hold the skin cap device securely against the skin around the peripheral base flange  31 , pushes the introducer body out through the newly-formed opening in the skin. This action serves to snap the wings  34  from the lateral walls  33  at the frangible connections  37 , and the blade with the wings still attached remains safely concealed within the recess  24 . 
     The introducer is pulled through the conical body  30  of the skin cap device until the appendant drain tube  23  emerges. This is then pulled to length and the surgeon then once again squeezes the two lateral walls  33  together to push the barb wings  38  against the outside surface of the tube. These barb wings serve to prevent the tube from inadvertently being pulled further out of the patient&#39;s body, and may be then held in this securing position by means of, for example, a length of inelastic tape around the external surface of the lateral walls  33 . 
     Finally, the projecting lugs  39  of the conical body  30  are securely sutured to the skin by way of the suture ports  40 . 
     The surgical implement of the invention thus ensures minimum risk of harm to both the patient and medical staff in the procedure of introducing the drain tube. Before use, the sharp edge of the blade is, by design, concealed in the interior of the skin cap device and so is highly unlikely to cause any accidental damage before use. Once the blade has been used to cut through the skin it is wholly concealed within the recess of the nose of the introducer, and said recess may be provided with a suitable arrangement for retaining the blade. For example, it may be designed to be slightly shorter than the depth to which the blade is to be driven to ensure the latter is embedded into the material of the introducer and is thus wholly captive therein. The skin cap device not only provides a simple way of accurately operating the incision blade with just two fingers of one hand, whilst fully protecting the fingers and the surrounding skin of the patient, but also doubles as a convenient and simple securing mechanism for the drain tubing, avoiding the need to attempt the conventional, somewhat unsatisfactory, direct suturing of the tube to the skin. Furthermore, by leaving the skin cap device in place, a relatively sterile zone is provided around the incision site, so helping to reduce the risk of microorganisms reaching the wound and tracking along the drain tube into the patient. 
     As mentioned above, both the introducer and the skin cap device are preferably fabricated from a semi-rigid plastics or latex material, with the flat metal blade mounted to the projecting wings  34  of the skin cap device. Both parts of the surgical implement are preferably provided as sterile disposable items, which may be packaged together or as separately selectable items, and are ideally designed for low cost mass production. 
     Clearly, the invention has application to a number of different types of surgical procedure, and the precise dimensions and characteristics of the surgical implement may be varied as appropriate to the particular application. For example, drain tubes might typically be required in the abdominal cavity during a laparotomy for peritonitis. In intestinal anastomoses, in plastic surgery and vascular surgery, and in surgical procedures in the field of obstetrics and gynaecology, such drains are also commonly employed. 
     The blade of the surgical implement might typically be of about 5 mm in length to make an incision which will accommodate a standard diameter of drain tubing, and the skin cap device might be a few centimetres in total diameter, being taller and wider for thicker or fatter skin types. The blade may alternatively be replaced by any other suitable incision element, such as an appropriately sized needle. 
     In addition to its use in conventional surgery, the surgical implement of the invention may find application in so-called ‘keyhole surgery’. In such procedures, the surgeon makes a first small opening in the skin from outside and then conventionally proceeds to make the additional access openings from outside the body. The invention may be employed by making use of an elongated introducer of arcuate form in combination with a skin cap device as hitherto described to form the second and subsequent openings, thus reducing the risk of inadvertently damaging the patient&#39;s viscera. An endoscopic instrument or attachment may be used to assist in guiding the introducer within the body. 
     It is to be noted in this description and the accompanying claims that the terms ‘distal’ and ‘proximal’ are used in a conventional sense, ie. with reference to the surgeon. For the introducer, therefore, the distal part is the part to be applied to the inner wall of the body cavity, and for the skin cap device the distal part is that part to be applied to the skin.