Catheter

Abstract: Catheter to be used in the skull area consisting of an elongated elastic tube (40) having a closed distal end (42) and having a connecting part (49) arranged at the rear end. The tube comprises an opening (44) at a predetermined distance from said distal end, the dimensions of said opening being sufficient for inserting an elongated manipulating needle (46) into the tube such that the distal point of said needle contacts the closed distal top of the catheter. Furthermore the tube may comprise a closure element (48) which is clamped around the tube and can be shifted along the tube between a first position in which said opening is covered by said closure element and at least one further position in which the opening is not obstructed.

Description: The invention relates to a catheter destined to extend through a subcutaneous tunnel and through an adjacent burr hole into the brain area, said catheter comprising an elongated elastic tube having a closed distal end and having a connecting part arranged at the rear proximal end, and comprises an opening at a predetermined distance from said distal end, the dimensions of said opening being sufficient for inserting an elongated manipulating needle into the tube such that the distal point of said needle contacts the closed distal end of the catheter and said predetermined distance being larger then the maximum length of the catheter to be introduced into the skull and shorter then the length of the manipulating needle. Catheters of the above-mentioned type, especially to be used predominantly in the area of the skull in case of operations, are generally known. An example of such a catheter destined for measuring intracranial pressure, is for instance described in US patent 3,669,094. The therein described catheter comprises an elongated drainage tube having a number of drainage openings near the distal tip of the tube and having connection means at the rear end to connect a pressure measuring device. The catheter, which is made from a relatively elastic and readily deformable material, is inserted into the cranium using an insertion rod which is shifted through the tubing until the distal end of the insertion rod meets the distal tip of the catheter. By means of this insertion rod the tubing is now inserted through a hole in the skull into the cranium, whereafter the insertion rod is at least partly removed to open the drainage holes near the distal portion of the catheter and to activate the pressure measuring means. A serious problem with this type of prior art catheters is the possibility of infection. Whenever an incision is made through the scalp of a patient there is a possibility that an infection may occur at the locus of the incision. Accordingly, when a short direct tunnel through the scalp and skull is maintained over a period of monitoring, a path may be provided for the infection to migrate to the subdural space. Even more seriously, if the arachnoid membrane encasing the brain is penetrated, there is a possibility of infection within the brain itself. This problem is recognized in US patent 4,114,603. Therein an intracranial pressure monitoring catheter is presented which is installed using a subcutaneous tunnel between the scalp and the skull. To install the catheter a first incision is made in the scalp and an aperture is formed which penetrates the skull and dura mater, but not the arachnoid membrane. A second scalp incision, spaced apart from the first, is then opened and a subcutaneous tunnel is formed between the incisions. The catheter is then introduced through the second incision, passed through the subcutaneous tunnel and the aperture in the skull and is then inserted into the subdural space between the arachnoid membrane and dura mater. The incision above the skull hole is then closed and the proximal end of the catheter is attached to a suitable pressure measuring device. To remove the catheter at the conclusion of the monitoring period it is only necessary to pull on a portion of the catheter external to the scalp. Nothing, however, is said about the way in which the catheter is inserted in the meandering path formed by the subcutaneous tunnel, the hole through the skull and the area underneath the skull. Especially in case the catheter has to be used for measuring intracranial pressure as in US 3,669,094 it will certainly be necessary to guide the catheter tip very carefully in a direction which can be almost perpendicular to the direction of the subcutaneous tunnel. A way to obtain a correct positioning of the catheter as a whole is described in US 4,692,155. The catheter tube described in US 4,692,155 is longer than most known catheters. By means of an inserting needle, which is brought in the catheter from the rear end until the tip of the inserting needle abuts the distal end, the catheter is inserted in the skull and moved into the correct position. Thereafter the part extending outwards from the skull is partly cut off, a cannula is connected to the remaining end of the catheter and a separate tubing, which is passed through a subcutaneous tunnel between the scalp and the skull is connected to the other side of the cannula. Thereafter the incision above the hole in the skull is closed so that ultimately a situation comparable with the situation illustrated in figure 2 of US 4,114,603 is obtained. The whole procedure of separately inserting the catheter in the skull and inserting the further tubing through the subcutaneous tunnel, cutting the catheter at the correct length after locating the catheter at the correct position, connecting the cannula to the catheter and connecting thereafter the further tubing to the cannula is considered very laborious and, because of the many parts involved, still has a certain risk on infection. A very similar catheter tube, which could be considered as a prefabricated version of the above-described catheter tube, is known from US-4,950,232. In this prior art device the actual catheter tube to become inserted into the burr hole and the drainage tubing to become inserted through the subcutaneous tunnel are beforehand connected by means of a joint piece. Although the risk on infection is decreased, still the use of separate sections connected by a jointing piece is considered a disadvantage. The object of the invention is now to provide a catheter which, in combination with an auxiliary manipulating needle or insertion rod can be inserted in the transcutaneous tunnel as well as through the hole in the skull and located at the correct position without having to cut the catheter and without having to use a separate cannula to connect the catheter to a further tubing, which runs through the transcutaneous tunnel. This object of the invention is reached by a catheter of the type mentioned in the first paragraph of this specification, which is characterized in that the catheter is made from one elongated elastic tube, the length of which is at least equal to the expected maximum length of the subcutaneous tunnel plus the maximum length of the catheter to be introduced into the skull plus a predetermined amount of excess length to enable proper manipulation of the catheter such that under all circumstances the proximal end of the catheter will remain outside the subcutaneous tunnel. As will be explained in more detail with reference to the attached drawings a surgeon is able to shift the catheter through the subcutaneous tunnel using the manipulating needle, draw a sufficient length of the catheter tube through said tunnel, insert thereafter the distal end of the catheter into the skull again using the manipulating needle, withdraw the excess length of catheter tubing back through the subcutaneous tunnel and close the incision above the hole in the skull. It is thereby not necessary to cut the catheter tubing. Dependent on the purpose of the catheter the hole in the catheter tube can be left open or has to be closed before the excess length of tubing is drawn back through the subcutaneous tunnel. If the opening has to be closed it is preferred that the catheter comprises a closure element which is clamped around the tube and can be shifted along the tube between a first position in which said opening is covered by said closure element and at least one further position in which the opening is free. In a specific embodiment the closure element consist of a short tube section fitting closely around the catheter tube such that the closure element can be moved between said aforementioned positions and such that the friction between the closure element and the catheter tube is sufficient to maintain the closure element in place during manipulation of the catheter, the length of said tube section being at least equal to the axial length of said opening. To facilitate insertion of the manipulating needle into the catheter it is preferred that the opening in the tube has an elliptical shape whereby the longest dimension of the opening is parallel to the axis of the catheter tube. If the catheter has to be applied for drainage purposes it is preferred that the catheter comprises near the distal end a number of passages rendering the catheter suitable for drainage purposes. However, if the catheter has to be used for measuring purposes it is preferred that the catheter carries at its distal tip a sensor for measuring a predetermined parameter of the space or matter in which the distal tip of the catheter is introduced whereby a communication line runs in general through the catheter tube from said sensor to the rear end of the catheter. Examples of parameters to be measured by a sensor on the distal tip of the catheter are pressure, oxygen content of blood or other fluid, glucose content of blood, temperature, pH-value of blood or other fluid, etc. The invention will be explained in more detail with reference to the attached drawings. Figure 1a illustrates very schematical a basic embodiment of a catheter according to the invention. Figure 1b illustrates a cross-sectional view through a part of the catheter of figure 1a. In figure 2a.....2f the method of using the catheter under operative conditions is illustrated in more detail. Figure 3 shows a cross-sectional view through the head of a patient illustrating the ultimate position of the catheter within the skull of a patient. Figures 4a and 4b illustrate a further developed embodiment of a catheter according to the invention. Figures 5a and 5b illustrate a another developed embodiment of a catheter according to the invention. Figures 6a and 6b illustrate a still further embodiment of a catheter according to the invention. Figure 1a illustrates schematically a very basic embodiment of a catheter according to the invention. The catheter consists of an elongated length of tubing 10 of a flexible easily sterilizable material, for instance a medical rate plastics or silicon rubber. The distal end portion 12 of the catheter is closed. At a predetermined distance from this distal portion the catheter comprises an opening 14 of which the dimensions are sufficient to enable the insertion of an manipulating needle which in figure 1 is shown as the elongated needle 16. Preferably the opening 14 has an elliptical shape to facillitate the insertion of the manipulating needle 16. The way in which this needle is used will be described in more detail with reference to figure 2. The rear end 20 of the catheter is embodied such that the catheter can be connected to for instance a pressure monitoring device if the catheter is to be used for pressure measurements or to a drainage tube if the catheter is to be used for drainage purposes. More specifically the rear end may comprise a so called Luer lock. It will be clear that if the catheter is used for drainage purposes the catheter should comprise a number of drain passages near the distal tip 12. Figure 1b illustrates a cross-sectional view through the catheter of figure 1a. Figure 2 illustrates in a series of perspective views, the way in which the catheter according to the invention can be used. The hands of the surgeon are schematically indicated by reference numbers 22 and 24. The skull of the patient is indicated by 26. It is remarked that for the sake of clearness the various reference numbers are not repeated in each of the figures 2a....2f. For inserting the catheter first of all a pair of incisions 32 and 34 spaced a predetermined distance apart are made through the patient's scalp. A burr hole 36 is drilled through the skull at the site of one of the incisions 34 and a subcutaneous tunnel is formed between the first incision and the second incision underneath the scalp but above the skull. Thereafter the manipulating needle 30 is through the hole 14 inserted into the distal section of the catheter 28 and by means of this manipulating needle 30 the catheter 28 is shifted through the subcutaneous tunnel to obtain the situation which is illustrated in figure 2a. Thereafter the manipulating needle 30 is removed by withdrawing the needle, the catheter 28 is drawn further through the subcutaneous tunnel until a situation is obtained in which a sufficient length of the catheter tubing is passed the subcutaneous tunnel to make it possible for the surgeon to insert the distal end of the catheter into the hole 36 in the skull. The situation obtained is illustrated in figure 2b. The surgeon inserts the manipulating needle 30 again through the hole 14 in the distal end of the catheter 28 as illustrated in figure 2c and thereafter starts the operation of inserting the catheter through the hole 36 in the skull into the brain region of the patient 26 as illustrated in figure 2d. As soon as the catheter is inserted far enough through the burr hole 36 the inserting needle 30, which was used during the insertion process, is removed. By pulling at the rear end of the catheter tubing, as is symbolised by the arrow 31 in figure 2e, the tubing is pulled back so that the tubing slack between the end of the subcutaneous tunnel and the burr hole 36 will disappear resulting in a situation as illustrated in figure 2f. After reaching the situation illustrated in figure 2f the first incision 34 is closed and if necessary the tubing coming out from the subcutaneous tunnel at the other incision 32 is secured to the scalp of the patient by sutures. Figure 3 illustrates in cross-sectional view the way in which the catheter runs 28 from the first incision 38 through the subcutaneous tunnel into the brain area. Figure 4a illustrates a further development of a catheter according to the invention. The catheter consists of an elongated length of tubing 40 of a flexible easily sterilizable material, for instance a medical rate plastics or silicon rubber. The distal end portion 42 of the catheter is closed. At a predetermined distance from this distal end portion the catheter comprises an opening 44 of which the dimensions are sufficient to enable the insertion of an manipulating needle which in figure 4a is shown as the elongated needle 46. Preferably the opening 44 has an elliptical shape to facilitate the insertion of the manipulating needle 46. Near the distal tip the catheter comprises a number of drainage passages 43 which can be arranged in the wall of the catheter tube in any convenient pattern. The catheter comprises furthermore a closure element 48 in the form of a short tube section which is shiftable along the tubing 40 between a position in which the closure element completely closes the opening 44 and at least another position, which is for instance shown in figure 4a, in which the opening 44 is free. The rear end 49 of the catheter is embodied such that the catheter can be connected to for instance a pressure monitoring device if the catheter is to be used for pressure measurements or to a drainage tube if the catheter is to be used for drainage purposes. Figure 4b illustrates a cross-sectional view through the catheter of figure 4a. As already remarked the closure element 48 is preferably embodied as a short tube section which fits closely around the tubular catheter 40 such that on the one hand the element 48 is movable between a position in which the hole 44 is open such as illustrated in figure 4b and a position in which the hole 44 is covered completely by the closure element 48, whereas on the other hand the friction between the element 48 and the tube 40 is sufficient to maintain the element 48 in place during the manipulation of the catheter. The manner in which the catheter according to figures 4a and 4b is used is in general the same as described with reference to figures 2a....2f. The difference is that between the step illustrated in figure 2d and the succeding step illustrated in figure 2e the closure element 48 is moved from the position in which the opening 44 is not obstructed to a position in which said opening is completely closed. It is possible to use the embodiment of the catheter illustrated in figure 1 and to close the opening 14 at the appropriate stage of the operation using a piece of plaster or tape but the application of a closure element as illustrated in figure 4 is preferred because it eases the handling of the catheter and provides better conditions for maintaining the catheter sterile. Figure 5a illustrates a another devellopment of a catheter according to the invention. Also in this embodiment the catheter consists of an elongated length of tubing 50 of a flexible easily sterilizable material, for instance a medical rate plastics or silicon rubber. The distal end portion of the catheter is closed and carries a transducer 51 for sensing a specific parameter of the space or matter in which the distal tip of the catheter will be introduced during usage. Examples of parameters to be measured by this sensor on the distal tip of the catheter are pressure, oxygen content of blood or other fluid, glucose content of blood, temperature, pH-value of blood or other fluid, etc. . A communication line runs in general through the catheter tube from said sensor to the rear end of the catheter in a manner which will be described with reference to figure 5b. At a predetermined distance from this distal end portion the catheter comprises an opening 54 destined to insert an manipulating needle which in is not shown seperately in this figure. The catheter comprises furthermore a closure element 58 in the form of a short tube section which is shiftable along the tubing 50 in the manner described already above with reference to figures 4a and 4b. The rear end of the catheter is in this embodied bifurcated and comprises a conventional Luer cone 56 and comprises furthermore a connector 57 for connecting the communication line from the transducer 51 to an external measuring or recording apparatus. Figure 5b illustrates a cross-sectional view through the catheter of figure 5a in the direction of the arrows Vb-Vb in figure 5a. As appears from figure 5b the catheter has a main passage 60 running through the tube from the closed distal end to the Luer cone 56 at the rear end and has furthermore an auxilliary passage 62 for accomodating the already mentioned communication line running from the transducer 51 at the distal tip of the catheter through the branch tube 55 to the connector 57. In case the transducer supplies electrical signals the communication line 64 may comprise a number of metal wires. However, sensors are known which provide optical signals and in that case the communication line 64 comprises one or more optical fibres. The use of a seperate channel for guiding the communication line offers the advantage that the risk of damaging the communication line by the manipulating needle is eliminated. A more sophisticated embodiment of the catheter is illustrated in figure 6a. As in the aforementioned embodiments the catheter consists of an elongated length of tubing 70 of which the closed distal end portion carries a transducer 71 for sensing a specific parameter of the space or matter in which the distal tip of the catheter will be introduced during usage. At a predetermined distance from this distal end portion the catheter comprises an opening 74 destined to insert an manipulating needle which in is not shown seperately in this figure. The catheter comprises furthermore a closure element 78 in the form of a short tube section which is shiftable along the tubing 70 in the manner described already above with reference to figures 4a and 4b. This closure element carries two fastening ears by means of which the closure element 78 can be fixed to the skull or skin of the patient in a known manner. The rear end of the catheter is in this embodied bifurcated and comprises a conventional Luer cone 76 and comprises furthermore a connector 77 for connecting the communication line, running in the above described manner through the catheter, to an external measuring or recording apparatus. The catheter has furthermore a number of drainage passages 73. Preferably the catheter is inserted through the transcutaneous tunnel (method steps illustrated in figure 2a) in combination with a protective tubular shield 80 of which an example is illustrated in figure 6b. The inner diameter of the tubular shielding element is approximately equal to the outer diameter of the catheter tube 70 so that the distal end of the catheter 70 can be inserted into the shielding element 80 until the distal tip of the catheter abuts the distal end of the shielding element. The external shape of the distal end of element 80 is selected to facilitate the insertion of the element 80 together with the catheter 70 through the subcutaneous tunnel. The shielding element 80 is preferably made of stainless steel and preferably has a length at least equal to the length of the subcutaneous tunnel so that this element 80 can be used in stead of the manipulating needle. As soon as the catheter has passed the subcutaneous tunnel (situation illustrated in figure 2b) the shielding element is removed and the further operation is carried out as described with reference to figures 2c...2f. The advantage of using the shielding element 80 resides in the fact that the distal section is completely protected and is still sterile in the situation according to figure 2b.

Claims: Catheter destined to extend through a subcutaneous tunnel and through an adjacent burr hole (36) into the brain area, said catheter comprising an elongated elastic tube (10) having a closed distal end (12; 42; 51; 71) and having a connecting part arranged at the rear proximal end (20; 49; 56; 76), and comprises an opening (14; 44; 54; 74) at a predetermined distance from said distal end (12; 42; 51; 71), the dimensions of said opening being sufficient for inserting an elongated manipulating needle (16;30;46) into the tube such that the distal point of said needle contacts the closed distal end (12; 42; 71) of the catheter and said predetermined distance being larger then the maximum length of the catheter to be introduced into the skull and shorter then the length of the manipulating needle, characterized in that the catheter is made from one elongated elastic tube, the length of which is at least equal to the expected maximum length of the subcutaneous tunnel plus the maximum length of the catheter to be introduced into the skull plus a predetermined amount of excess length to enable proper manipulation of the catheter such that under all circumstances the proximal end of the catheter will remain outside the subcutaneous tunnel. Catheter according to claim 1, characterized in that the catheter comprises a closure element (48; 58) which is clamped around the tube (40; 50) and can be shifted along the tube between a first position in which said opening (44; 54) is covered by said closure element and at least one further position in which the opening is not obstructed. Catheter according to claim 2, characterized in that the closure element (48; 58) consist of a short tube section fitting closely around the catheter tube such that the closure element can be moved between said aforementioned positions and such that the friction between the closure element and the catheter tube is sufficient to maintain the closure element in place during manipulation of the catheter, the length of said tube section being at least equal to the axial length of said opening. Catheter according to one of the preceding claims, characterized in that the opening in the tube has an elliptical shape whereby the longest dimension of the opening is parallel to the axis of the catheter tube. Catheter according to one of the preceding claims, characterized in that the catheter comprises near the distal end a number of passages (43; 73) rendering the catheter suitable for drainage purposes. Catheter according to one of the preceding claims, characterized in that the catheter carries at its distal tip a sensor (51) for measuring a predetermined parameter of the space or matter in which the distal tip of the catheter is introduced whereby a communication line (64) runs through the catheter tube from said sensor to the rear end of the catheter. Catheter according to claim 6, characterized in that at least a section of the communication line runs through a longitudinal channel (62) in the catheter wall separate from the inner space (60) in which the manipulating needle can be inserted. Catheter according to claim 6, characterized in that said section of the communication line is embedded in the wall of the catheter tube. Catheter according to one of the preceding claims, characterized in that the catheter is used in combination with a tubular shielding device (80) which fits closely around the distal end of the catheter and is destined to maintain the sterility of the respective distal end of the catheter.

Inventors: BUIJS ARNOLD, NIEUWESTEEG MICHAEL WILHELMUS, BUIJS, ARNOLD, NIEUWESTEEG,MICHAEL WILHELMUS CLEMENS MARIA
Applicants: DRAEGER MED ELECTRONICS BV, DRAEGER MEDICAL ELECTRONICS B.V.
Application year: 1991
Main classification: A61M25
IPC codes: A61M25, A61M27