Catheter for transporting biological fluids and solutes thereof

Abstract

The invention relates to an implantable catheter able to generate an autonomous flow of liquid therein, formed by a tubular body (1) in which is defined an internal structure (2) that determines two separate conduits (3-3') defining two lumens which, at one end, open at different points and therefore at a different height of the cavity in which the catheter is disposed, one conduit being larger than the other. The flow moves naturally in the cavity or system by means of a pressure gradient existing along same. This pressure gradient is transmitted through the holes of each conduit of the catheter, meaning that the pressure at a given moment is different in each end hole, generating an autonomous flow not actively forced through the catheter. This continuous flow of biological fluid can be used to administer drugs in a controlled manner, filter fluid, etc. By interposing one or more valves in one or more lumens or interposed devices, the flow can be made predominantly one way or the speed of the liquid can be altered.

Description

[0001] DESCRIPTION

[0002] Catheter for the transport of biological fluids and their solutes.

[0003] TECHNICAL SECTOR

[0004] The present invention relates to a catheter specially designed for implantation in the body.

[0005] OBJECT OF THE INVENTION

[0006] The object of the invention is to provide a catheter that allows generating a completely autonomous flow of body fluid in a closed circuit, without the support of active flow systems, whether unidirectional or bidirectional, thus also being able to facilitate the transport of diluted solutes from one point to another in the circuit.

[0007] BACKGROUND OF THE INVENTION

[0008] Catheters are used in clinical or preclinical settings as platforms for extracting or introducing physiological or pathological fluids or drugs. They are communication channels between the body and the outside world.

[0009] The liquids that circulate through it are actively forced artificially, aspirated or effused, either by a syringe, a small motor as in peristaltic pumps (e.g. infusion pumps, implantable, hemodialysis, etc.), or naturally by the difference in pressure of the liquid inside the organism with respect to the external pressure, as in cerebrospinal fluid drainage or blood extraction,

[0010] Molecules diluted in a fluid within a tubular structure can be transported from one point to another either because there is a forced directional flow of the fluid; or in the case of a static or oscillating fluid, these molecules can move solely or predominantly in one direction due to differences in molecular concentration, this process being much slower.

[0011] REPLACEMENT SHEET (RULE 26) In contrast to the catheter's sole function of communicating fluids, achieving a non-actively forced flow of body fluids within a closed system such as a catheter could be of interest for applications such as filtration, clearance, or drug delivery while passing fluids. It is desirable to avoid the use of electromechanical equipment or altering the pressures and volumes of body fluids.

[0012] The applicant is unaware of the existence of catheters that allow for the generation of autonomous flow within them for this type of application in CSF or any other type of bodily fluid. Therefore, the closest known state of the art for CSF is presented below, but this problem extends to other bodily fluids.

[0013] Single-lumen intrathecal catheters:

[0014] Access to the subarachnoid space, bypassing the blood-brain barrier, can be achieved cranially, reaching the ventricles, or in the spinal region, usually the lumbar region. The latter is known as intrathecal access and is commonly used for the administration of certain analgesic drugs or for the drainage of cerebrospinal fluid (CSF). Both approaches can be used for drug administration, CSF drainage, and pressure monitoring using different types of catheters.

[0015] At the ventricular level, a common access is the so-called Ommaya reservoir. This long-term implant involves placing a subcutaneous reservoir in the scalp, and a catheter connects this reservoir to one of the cerebral ventricles, providing direct access to the CSF.

[0016] Ventricular catheters are also available for the treatment of hydrocephalus. These catheters connect the inside of the ventricle to the outside, the peritoneum, or the atrium of the heart to control excess CSF.

[0017] Enclear Therapies is developing an extracorporeal CSF filtration and monitoring system with two subcutaneous access ports that reach the subarachnoid space via catheters in the ventricular and lumbar areas. When both are

[0018] REPLACEMENT SHEET (RULE 26) connect to an active extracorporeal pumping system, closing the circuit through which the CSF circulates.

[0019] Alcyone Therapeutics is developing a new central nervous system drug delivery system called The ThecaFlex DRx™, using an intrathecal catheter and a subcutaneous reservoir. This is solely a bolus drug delivery system. Details of the catheter are unknown.

[0020] There are several simple catheters used for intrathecal (lumbar) drug administration using implantable infusion pumps, such as the Ascenda catheter that attaches to the Synchromed pump, both products of the Medtronic company.

[0021] Double or two-lumen intrathecal catheter:

[0022] There are known experimental double-lumen catheters used in neurology, such as the Neurapheresis™ system from Minnetronix Neuro to treat acute subarachnoid hemorrhage by means of extracorporeal filtration of blood present in the CSF.

[0023] This is a coaxial catheter in which a longer, narrower lumen is located inside a second, shorter, wider lumen. This differentiates the CSF aspiration and return ports in the spinal canal by height once the CSF has passed through an active extracorporeal peristaltic pumping and filtration system to remove blood. The catheter connects the intrathecal space (at two different heights) with the external filtration platform. The different heights of the ports are intended to prevent the aspiration of newly returned CSF, thus avoiding the filtration of already filtered CSF. It is a short-term implant, with Neurapheresis sessions of up to 72 hours in a hospital setting, according to the PILLAR-XT clinical trial.

[0024] There is another double-lumen catheter, part of the active fluid exchange system called IRRAflow, which is a catheter implanted intraventricularly to treat acute critical neurological conditions in a hospital setting. It was designed to allow active intraventricular fluid exchange, enabling the irrigation of physiological fluids and the drainage of pathological material (e.g., blood). It is a double-lumen catheter that, thanks to its connection to an external pump, allows CSF drainage through one lumen and drainage through the other.

[0025] REPLACEMENT SHEET (RULE 26) fluid irrigation. Both lumens terminate at the same distal level. Fluid flow is active thanks to the external pump, not the catheter itself.

[0026] Regarding industrial property registrations relating to devices of this type, the following are worth highlighting:

[0027] Patent ES2694698A1 concerns an implantable device for the removal of toxic molecules from cerebrospinal fluid. It consists of a double-lumen catheter with the lumens of the same length. One end of the catheter is in contact with the cerebrospinal fluid (CSF), while the other end features a capsule with two chambers separated by an intermediate partition.

[0028] The reality is that, contrary to what is described in said patent, the applicant has been able to experimentally verify how the fact that the lumens have the same length at the ends in contact with the CSF, prevents any autonomous movement of the CSF from occurring, since the pressure of the CSF would be equal at both ends and would try to enter both holes equally, eliminating the possibility of generating any movement inside the device.

[0029] To do this, it is necessary to generate a pressure difference between the tips of the tubes that passively allows autonomous movement of the CSF inside the tubes.

[0030] Although patent US2021386981 A1, by Minnetronix Neuro, discloses a series of catheter designs whose tubes have different lengths, these are assisted by a pump that can be connected between both lumens to induce CSF flow, aspirating endogenous CSF through one of the lumens, conditioning it on the outside and returning the treated CSF through the second lumen at a different height from the first. The CSF flow is actively forced by a peristaltic pump, essential to achieve the objective of the described patent. Therefore, the different height of the lumens is not intended to generate a passive flow of CSF, but rather prevents the CSF that has recently returned from being aspirated again, thus maximizing the endogenous volume that is finally conditioned.

[0031] In this same document US2021386981 A1 it is discussed the turbulence generated at the

[0032] REPLACEMENT SHEET (RULE 26) outlet from the end of the return catheter, which aims to improve the mixing of conditioned and unconditioned (or endogenous) CSF, helping to reduce and homogenize the concentration of the target molecule in the total volume. It is described that these turbulences can be encouraged to a greater or lesser extent depending on different configurations of the pump (e.g., high-pressure injection) and the catheter (e.g., multiple ports, balloons, different textures, etc.).

[0033] In any case, as previously stated, this is not a passive device, as it uses a peristaltic pump to generate CSF flow through the catheter. Therefore, the different lengths of the lumens are not intended to generate a passive flow of CSF within the catheter.

[0034] In the case of patent US11123483B2, whose catheter is that of the IRRAflow system, it is not intended to produce a flow of CSF or fluids autonomously, since it needs to be connected to a peristaltic pump for fluid exchange.

[0035] Consequently, there is no known catheter in the field of CSF or other body fluid interventions that can generate autonomous flow in a closed system without the need for assistance from other components such as electromechanical pumps.

[0036] EXPLANATION OF THE INVENTION

[0037] The intrathecal or intraventricular catheter proposed by the invention fills the technical gap described above, based on a simple but highly effective solution.

[0038] To this end, the catheter of the invention is constituted from a double-lumen catheter, designed to generate a closed circuit, which allows generating a flow of CSF or other body fluids and effective transport of molecules without the need for assistance from other active components such as electromechanical pumps.

[0039] Its structure also allows the insertion of other components into the closed circuit, such as reservoirs and / or ports, which, located at the subcutaneous level or outside the

[0040] REPLACEMENT SHEET (RULE 26) organism, allow it to interact with CSF or other moving body fluids in different ways.

[0041] More specifically, the catheter is constructed from a tubular body with an internal morphology that determines two independent channels, defining two lumens. To generate movement, the fluid must present a different instantaneous pressure at each of the lumen orifices. This is achieved by positioning the terminal ends of the lumens at different heights within the same cavity or system of body fluids that exhibit a spatiotemporal evolution of internal pressures.

[0042] This allows CSF to move naturally within the spinal canal due to a pressure gradient along its length. These pressures are transmitted through the openings of each of the catheter's ducts. This instantaneous pressure difference at the end openings allows for a non-zero net flow within the catheter.

[0043] Based on this design, the catheter of the invention can be specifically configured into a closed circuit for various applications, in which CSF or other bodily fluids move through the conduits in a natural flow rather than being actively forced. These fluids can be treated within the closed circuit itself, either by administering injected substances into reservoirs or serial ports and / or by modifying the composition of the fluid through the use of filters or membranes.

[0044] In accordance with another feature of the invention, non-return systems can optionally be installed in the two conduits defined within the catheter to promote flow in one direction, or a bidirectional movement (swelling) can be defined due to possible pulsatility, when such systems are not available. In this regard, it has been envisaged that a valve system composed of one or more valves arranged in one or both lumens of the catheter can be included. In the latter case, they would be placed in opposite directions in each of the lumens, such that they can act synergistically to enhance the flow of liquid while simultaneously promoting the inflow and outflow to a device connected in series predominantly in one of the directions.

[0045] REPLACEMENT SHEET (RULE 26) Likewise, the physicochemical characteristics of the catheter can also be modified in its composition, dimensions or geometry, so as to enhance the flow of CSF or the effective transport of solutes diluted in it.

[0046] DESCRIPTION OF THE DRAWINGS

[0047] To complement the description that follows and in order to help better understand the characteristics of the invention, in accordance with a preferred example of practical implementation thereof, a set of drawings is attached as an integral part of said description, in which the following has been represented for illustrative and non-limiting purposes:

[0048] Figure 1 shows a perspective view of an intrathecal catheter made in accordance with the object of the present invention.

[0049] Figure 2.- Shows a sectional view of the catheter in the previous figure, with a possible geometry for it.

[0050] Figure 3.- Shows a schematic drawing of the implantation mode of the catheter of the invention.

[0051] Figure 4.- Finally, it shows a side elevation view of a variant embodiment of the catheter, which includes side holes on both independent ducts.

[0052] PREFERRED EMBODIMENT OF THE INVENTION

[0053] In view of the figures shown, it can be observed how the device of the invention is constituted from a tubular body (1), which will have a length adapted to its final application, with a uniform or variable diameter and in which an internal morphology (2) is established that determines two independent conduits (3-3') inside said tubular body, defining a double-lumen catheter.

[0054] REPLACEMENT SHEET (RULE 26) Well, according to the essence of the invention, and as can be seen in figures 1 and 3, the independent ducts (3-3') of the end (4) of the catheter to be implanted for example intrathecal zone (5) open into different points (6-6') conveniently spaced apart from each other. The exit / entrance (6-6') of the ducts can be made by means of a single hole in the end (4) and / or by means of additional lateral holes (7) according to a convenient distribution.

[0055] Returning to Figure 3, this allows that, in the case of CSF, it moves naturally inside the spinal canal or intrathecal region (5) by a pressure gradient existing along it, these pressures are transmitted through the holes (6-6') of each of the ducts (3-3') of the catheter, whose difference generates a natural flow of said CSF through them. Said ducts can be connected in series by their opposite end to one or more elements (8), which can materialize in a reservoir or port to administer substances, and / or filters or membranes.

[0056] As for the internal morphology (2) that determines the two ducts (3-3'), this can be indistinctly symmetrical, as it appears in the figures, or asymmetrical, without affecting the essence of the invention.

[0057] It only remains to point out finally that, given that the movement of CSF or other body fluids can be naturally bidirectional (waves), either the conduits (3-3') can be provided with internal or external non-return systems (9-9') based on one or more valves arranged at any height in one or both lumens of the catheter that force the flow in one direction, or they can act synergistically to enhance the flow of fluid while favoring flow predominantly in one of the directions. The position and frequency of these non-return systems can vary in order to adjust the flow rate.

[0058] This creates a catheter that, without the support of active flow systems, allows for completely autonomous movement of cerebrospinal fluid (CSF), either unidirectional or bidirectional, in a closed circuit. This also applies to other bodily fluids that exhibit pulsatility and may present different pressures at different heights within the cavity or system in which they are located.

[0059] REPLACEMENT SHEET (RULE 26)

Claims

CLAIMS 1 a.- Catheter for the transport of biological fluids and their solutes, which is intended to generate an autonomous movement of the body fluid not actively forced in a closed circuit through said catheter, is characterized in that it is constituted from a tubular body (1), in which an internal morphology (2) determining two independent ducts (3-3 ') is established inside said tubular body, in which said ducts open into points (6-6') longitudinally spaced from each other in correspondence with the end (4) of the catheter intended to be implanted in the intrathecal region (5) or in another body cavity, it having been provided that the opposite end of said catheter is connected in series through the independent ducts (3-3') to one or more elements (8) such as reservoirs or ports, flow enhancement systems, filters or membranes, (8),defining a passive flow system of body fluid for drug delivery or fluid filtration. 2 a .- Catheter for the transport of biological fluids and their solutes, according to claim 1 a , characterized in that the conduits (3-3') are provided with an internal or external non-return system (9-9') that determines the flow direction and an effective transport of solutes predominantly in one direction in one or both conduits, in which one or more valves or non-return systems properly spaced may participate. 3 a .- Catheter for the transport of biological fluids and their solutes, according to claim 1 a , characterized in that the tubular body (1) has a uniform diameter. 4 a .- Catheter for the transport of biological fluids and their solutes, according to claim 1 a , characterized in that the tubular body (1) has a variable diameter. 5 a .- Catheter for the transport of biological fluids and their solutes, according to claim 1 a , characterized in that the end (4) of the catheter intended to be implanted in body cavities filled with biological fluids of any system of the organism, such as for example the intrathecal space (5) or others such as arteries or veins, has lateral inlets (7) conveniently distributed around the mouth (6-6') of the ducts (3-3'). REPLACEMENT SHEET (RULE 26) 6 a .- Catheter for the transport of biological fluids and their solutes, according to claim 1 a , characterized by the fact that the internal morphology (2) that determines the two ducts (3-3') presents symmetry. 7 a .- Catheter for the transport of biological fluids and their solutes, according to claim 1 a, characterized by the fact that the internal morphology (2) that determines the two ducts (3-3') presents an asymmetric distribution REPLACEMENT SHEET (RULE 26)

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