The object of the invention is a dialysis catheter assembly, in which the vascular needle is mounted with a guide, used in the configuration of a single-needle dialysis, in particular hemodialysis by arteriovenous fistula.

Metal or plastic needles are usually used to puncture the arteriovenous fistula each time during hemodialysis. Single-needle dialysis uses a single needle, which serves both for aspiration and as well as returning blood after purification in an artificial kidney. The insertion of such a needle, having a cross section of a pipe, into the blood vessel is done in a standard way by puncture of the fistula with or without the use of a stasis to achieve better filling. When the needle is placed in the blood vessel, it is covered with band-aids and hemodialysis begins. In many cases, especially when the fistula is not sufficiently mature, i.e. when the diameter of the vessel is less than 6 mm or is deep in the subcutaneous tissues, insertion of the needle may cause problems with proper localization of the vessel and risk of its puncture, occurrence of hematoma around the vessel, its narrowing and finally the fistula thrombosis, which requires surgery. These situations are often observed shortly after the fistula creation, as well as in patients from risk group of prolonged maturation (patients with diabetes and arteriosclerosis) or in obese patients whose vessels may also be located under a thick layer of fat tissue. It is estimated that about 40% of patients with native fistula have problems by fistula needling. In those patients it is necessary to implant the catheter into the central vessels. This type of vascular access is associated with an increased risk of catheter related infections, other non-infection complications, and patients are more likely to be hospitalized and have an increased risk of death.

US patent US4134402A discloses a double lumen continuous flow hemodialysis needle and cannula, having contiguous lumens of different lengths. The shorter lumen acting as blood intake lumen and the longer as a blood return lumen. Each lumen having a beveled edge which can be inserted percutaneously and which minimizes the possibility of mixing cleansed blood with blood entering the intake lumen.

Another US patent application US4037599A discloses a catheter device used in the catherization of a blood vessel during hemodialysis, the said catheter comprising a hub assembly having at least a first and second fluid conduit each of which are connected in fluid communication with separate concentrically disposed tube elements so as to define a first and second fluid flow path. The concentrically arranged tube elements provide for a single puncture into the predetermined blood vessel wherein the first and second fluid conduits are interconnected to a continuous negative and positive source of fluid flow so that blood will be continuously drawn from and supplied to the predetermined blood vessel by means of the outer and inner tube elements respectively. The hub assembly may comprise at least two hub portions correspondingly dimensioned and configured to define the two fluid conduits therein and also provide structure for securing the inner and outer tube elements to the hub assembly and further provide alignment structure for properly positioning the two hub portions into mating engagement with one another to define the operative hub assembly.

US patent US6962575B2 discloses a single access dialysis needle system comprising a first cannula, a second cannula or sheath, and a barrier arranged on the outer surface of the first cannula. The distal end of the first cannula extends distal to the distal end of the second cannula or outer sheath, and the barrier is positioned between the respective distal ends. When the barrier is inflated or otherwise activated, it prevents or minimizes recirculation.

US patent US5279590A discloses the apparatus for introducing a catheter into a patient's vein which comprises a tubular housing having an axially extending guide slot extending from a point adjacent the forward end of the housing to a point adjacent the rear end of the housing. A tubular transparent mount for a hollow hypodermic needle is slidably mounted in the tubular housing with the sharpened end of the needle projecting forwardly. The overall length of the needle mount and needle is less than the length of the housing. A locking element rotatably mounted on the needle mount projects through the elongated slot and is selectively engaged with recesses provided in the forward and rear end wall portions of the elongated slot, by rotation relative to the needle mount, to lock the needle mount in an operative position with the needle projecting out of the housing, or an inoperative position with the needle retracted into the housing. A short length catheter or an axially splittable introducer sheath may be mounted on the needle in its projecting position for insertion with the needle into the patient's vein. After insertion of either a catheter or a catheter introducer sheath in the patient's vein, the needle is retracted from the vein to its inoperative position and the exposed opening in the sharpened end of the needle is surrounded and sealed by a mass of elastomeric material mounted in the forward end of the bore of the housing.

European patent application EP1622671 B1 discloses an assembly comprising an aspiration needle and a needle protective tube, used for introducing a short length catheter into a patient's blood vessel. An assembly comprises an aspiration needle consisting of a needle tube one end of which is bevelled, and a base integral with the other end of the needle tube, and a protective tube for this needle, this protective tube having a longitudinal slot which allows a needle tube to slide in the protective tube by actuating a portion of the needle external to the protective tube. The said protective tube is a flexible tube with a diameter that is able to entirely accommodate rectilinear portion of the needle tube, said base of the needle being entirely located outside the protective tube and slidably mounted on the protective tube between a front position where said rectilinear portion protrudes in front of the protective tube and a rear position where said rectilinear portion is contained in the protective tube. Additionally, longitudinal slot of the protective tube is extending right up to the front end of the protective tube and has an elastic opening so as to open in order to allow the bent portion of the needle tube to pass through the slot and to close after this passing. In the said assembly a suitable cannula is inserted into the vessel at the same time as the needle and an additional protective tube mounted. In this case an increased risk of posterior wall puncture, extravasation and hematoma, similar to the puncture with a standard dialysis needle, due to the comparable diameter of both devices. Additionally, the said assembly cannot be used for single-needle dialysis because it only has one fluid conduit.

The Seldinger technique has been well known and used in radiology, interventional cardiology and nephrology for many years for introducing sheath passages in endovascular procedures for venous and arterial venous as well as hemodialysis catheters implanted into central vessels. The technique of inserting catheters using a guidewire, i.e. the Seldinger technique consists in puncturing the vessel with a test needle, inserting the guidewire, withdrawing the needle, widening the insertion site with the dilator and inserting the correct cannula. This method is mainly used for implantation catheters into central vessels and surgical radiology procedures, including intervention cardiology. In endovascular procedures sheath passages with a stylet are used. Sheath passages at the distal end are terminated with a hemostatic valve with lateral tubing with a stopcock for flushing the sheath passage. This design prevents the blood from flowing. However, it should be noted that such sheath passages have an indelible valve that blocks the outflow of blood, preventing blood supply during dialysis. Moreover, such sheath passages do not have appropriate tip for connecting the dialysis blood line where a special type of thread is required, while connecting the dialysis line to a lateral conduit usually characterized by a small diameter (1-2 mm) and disproportionately large length (11 cm), will result in high flow resistance during dialysis when the average blood flow is between 250 - 350 ml/min. Moreover, the prior art sheath passages are usually constructed of a uniform, rather rigid material that is subject to limited strains.

The technical problem to be solved by the present invention is to propose a set of dialysis catheter assembly that will be adapted for single-needle dialysis, in particular hemodialysis by arteriovenous fistula and will increase the precision of catheter placement in a given blood vessel and will also help to reduce the risk of puncturing a blood vessel and occurrence of other complications such as hematoma,vein stenosis and thrombosis. It is also preferable that a dialysis catheter assembly allows for a more accurate finding of an inaccessible blood vessel, such as a fistula in the upper limb tissues, allows the atraumatic puncture of even "immature" fistulae, and at the same time has a simple construction, easy to produce, gaining economic advantages. Surprisingly, the above-mentioned technical issues have been solved by the invention shown.

The object of the invention is a dialysis catheter assembly, comprising a test needle, guidewire, stylet, main cannula and at least one seal, wherein in the proximal part the main cannula comprises a vascular lumen connected with a rigid base of the lumen, in which common conduit extends to the distal end, branching out at least to a first arm conduit and a second arm conduit, the distal end of the first arm having a tip and the distal end of the lateral conduit having a tip, characterized in that the vascular lumen is made of elastic plastic, preferably of polyvinylchloride with the addition of di-2-ethylhexyl phthalate (DEHP), polyurethane or its medically acceptable thermoplastic variants such as Carbothane, in the branch part of a common conduit into the first arm conduits and second arm lateral conduit it is made of a soft material fully compressible under the force of less than 25 N, preferably of biocompatible silicone, and the tips are made of a rigid material, preferably of polyvinyl chloride, meeting the medical requirements of CE.

In preferred embodiment of the invention the ratio of the main cannula length to the inner diameter of the vascular lumen is in the range of 11 .5 to 23.75.

In another preferred embodiment of the invention the inner diameter of the vascular lumen is in the range of 1.3 mm to 2.0 mm.

In another preferred embodiment of the invention the length of the main cannula is in the range of 15 mm to 38 mm.

Fluid flow is preferably in the range of 200 ml/min to 500ml/min, with a pressure difference of less than 200mmHg.

Equally preferably, the tip comprises a dialysis line thread at the distal end.

More preferably the seal is a lumen, closed from the distal end, having a thread, corresponding to the dialysis line thread, on the tip. In preferred embodiment of the invention the seal additionally has a blocking lumen, protruding from the proximal side, with an outer diameter closely tied to the inner diameter of the distal tip.

In another preferred embodiment of the invention a guidwire is a rod, preferably made of stainless steel and nitinol with a hydrogel coating, which has a flexible, soft safety tip to prevent perforation of the vessel in the proximal part, and in the distal part it is rigid.

In yet another preferred embodiment of the invention a main cannula is equipped with wings to attach the main cannula to the skin.

The dialysis catheter assembly comprises a cannula for hemodialysis inserted using a guidewire in the assembly with auxiliary elements, i.e. test needle, guidewire, stylet and two seals, therefore it can be used in dialysis patients whose arteriovenous fistula is not mature enough to use it safely in a traditional way, i.e. using traditional cannulas. The use of a small diameter test needle in the situation when it is difficult to locate the right vessel in the tissues is not causing traumatism and blood extravasation. In addition, the insertion of the guidewire causes the risk of puncture of the blood vessel when inserting the right cannula is very limited, and the insertion process itself is greatly facilitated. The dialysis catheter assembly according to the invention can be used in a much larger number patients, in the case of whom despite the functioning fistula, it was not possible to safely puncture it due to, e.g., atypical location, deep location or small vessel dimensions. The use of a short length dialysis catheter with an increased diameter in the dialysis cannula allows for the required hemodialysis volume of fluids. Additionally, in the middle hub the cannula is made of soft biocompatible silicone, which allows compression of cannula for hemodialysis at the moment of removal of the stylet, with a force of no more than 25 N (corresponding to approximately 2.5 kg of pressure allowing this to be done with finger compression without the use of additional tools), therefore blood loss when connecting blood lines is prevented. In addition, the entire dialysis catheter assembly is simple in design, without complex shapes, which provides economic benefits for the manufacture and increases the reliability of the solution of the invention.

Exemplary embodiments of the invention are shown in the drawing, in which Fig. 1 shows a cross-section of a catheter assembly (cannula inserted through the stylet in a working position) for dialysis according to one embodiment of the present invention; fig. 2 shows a cross-section of the cannula after removing the stylet, fig. 3 shows a cross-section of a test needle of the dialysis catheter assembly according to one embodiment of the present invention, fig. 4 shows a cross-section of a guidwire, fig. 5 is a side view of a stylet of the dialysis catheter assembly according to one embodiment of the present invention, while fig. 6 shows a cross-section of a seal to the closure of the cannula arm.

Example

Figures 1 to 6 present a dialysis catheter assembly according to one embodiment of the present invention. Fig. 1 shows a dialysis catheter assembly in an assembled state, which comprises a cannula K (shown as a separate element in fig. 2) including a vascular lumen 1a, made of flexible material (such as polyvinylchloride with the addition of di-2-ethylhexyl phthalate (DEHP)meeting the medical requirements of CE or polyurethane in particular the thermoplastic polyurethane commercially available under the trade name Carbothane®, with an internal diameter slightly larger than the diameter of the stylet M (shown as a separate element in Fig. 5). A vascular lumen 1a in the distal part is attached to the distal part and wings are attached 2a. The attachment of the wings 2a can be rigid or loose allowing a rotational movement about the axis of the base of the lumen 1 when the wings 2a are additionally provided with an outer ring 2b around the base of the lumen 1. A common conduit 3a and firm arm conduit 3b are attached to the base of the lumen 1 in such a way that they are located in the long axis of the base of the lumen 1 , the proximal end of the common conduit 3a being tightly coupled to the base of the lumen 1. Middle hub of the cannula K is made of a soft material fully compressible under the force of less than 25 N (corresponding to the applied weight of about 2.5 kg) preferably of biocompatible silicone. The choice of such material for the construction of the middle hub of the cannula K was dictated by the need to ensure the compression capability of the common conduit 3a when compressing the he catheter assembly of the present invention by the fingers of operator (without the use of additional tools). A second arm lateral conduit 3c is branched from the common conduit 3a at an acute angle of about 30°such that the opening of the channel of the second arm conduit 3c communicates with the opening of the common conduit 3a and the first arm conduit 3b. The distal end of the first arm conduit 3a is tightly connected to the tip 4b in the form of a rigid lumen terminated at the distal end with the thread of the dialysis line 4a, while a distal arm of second conduit arm 3c is tightly connected to the tip 5b, in the form of a rigid lumen, terminated at the distal end with the thread of the dialysis line 5a. In the present embodiment the tips 4b and 5b are made of rigid material, i.e. of polyvinylchloride meeting the medical requirements of CE. In the embodiment of the present invention the inner diameter of the vascular lumen 1a is 1.6 mm, while the length of the cannula K is 20 mm. The ratio of the cannula K length to the inner diameter of the vascular lumen la in this case is 12.5 and thus provides a flow of 350 ml/min at a pressure difference of about 160 mm Hg. Such working parameters are extremely important for ensuring the proper functioning of the dialysis catheter assembly of the present invention during hemodialysis. Depending on the anatomy of the blood vessels, the inner diameter of the vascular lumen 1a in other embodiments may range from 1.3 mm to 2.0 mm, while the length of the cannula K may range from 15 mm to 38 mm, while maintaining the ratio of cannula K length to the inner diameter of the vascular lumen 1a, ranging from 1 1.5 to 23.75. Particularly preferred is the use of cannula K parameters, especially the internal diameter of the vascular lumen 1 a that have been established in the field and are standards such as: G14 - 2 mm, G15 - 1.8 mm, G16 - 1.6 mm, G17 - 1.5 mm and G18 - 1.3 mm. In this way dialysis catheter assemblys of the present invention will provide flows ranging from 200 ml/min to 500 ml/min at a pressure difference of less than 200 mmHg, which is necessary for effective hemodialysis of the patient.

Stylet M (fig. 5) comprises a lumen 10 whose outer diameter is slightly smaller than the inner diameter of the vascular lumen 1a. The lumen 10 is made of polyvinylchloride meeting the medical requirements of CE and in a distal part engages with the base of the stylet M made in the form of a rigid lumen, whose shape provides for the smooth removal of the stylet M from the cannula K at the final stage of insertion of the dialysis catheter assembly of the present invention. The conical, through conduit 11a extending in the distal direction of the base of the stylet 11 is made inside the base of the stylet 11 such that its opening is tightly coupled to the opening of the stylet 1 1 lumen, enabling inserting the guidewire P (shown as a separate element in Fig. 4).

A test needle shown in Fig. 3 IP comprises a needle tube 6 made of stainless steel 316L and a base 7 made of a rigid polymer, e.g. polyacetal, the opening of the conical needle base channel 7a being tightly coupled to the opening of the needle tube 6. The inner diameter of the needle tube 6 is slightly smaller than the diameter of the guidewire P. The guidewire P is a thin rod made of stainless steel and nitinol with a hydrogel coating, which has a flexible, soft safety tip 8 to prevent perforation of the vessel in the proximal part 8, and in the distal part it is rigid 9, the safety tip 8 and the distal part of the guidewire 9 being connected such that it is not possible to accidentally separate them without intentional cut.

The seal KK shown in Fig. 6 has a shape of a short, rigid lumen 12 closed from the distal side and open from the proximal side, the inner surface of the lumen 12 being provided with a thread 12a compatible with the thread of the cannula tips 4a and 5a and a locking lumen 12b being provided inside the lumen 12, the outer diameter of which closely matched the inner diameter of the distal portions of the lumens 4b and 5b.

The method of inserting a dialysis catheter assembly according to the present invention is that a needle is punctured into the vessel by means of an IP test needle, followed by guidewire P inserted into the blood vessel. Subsequently, the test needle IP is removed from the patient's body, leaving the guidewire P in, and then in the axis of the guidewire P a stylet M is inserted into the vessel, located in the main cannula K. The lateral arm (i.e. the second arm lateral conduit 3c) of the cannula K is closed with a seal KK. Then the stylet M is being removed, leaving the vascular lumen 1a of the main cannula K in the opening of the vessel (e.g. arteriovenous fistula). Blood flow is blocked by the compression of the middle hub of the cannula K, and then blood lines are connected, whereby the opening of the common conduit 3a of the cannula K is closed by screwing the second seal KK. Then, the main cannula K is attached to the patient's skin with the wings 2a, using a self-adhesive patch or band.