Double-lumen cannula

Abstract

The present invention relates to a dual lumen cannula that is configured to be inserted into a patient's body simply like a single lumen cannula. The dual lumen cannula has at least one inner lumen, the at least one inner lumen having at least two ends, an inner lumen proximal end and an inner lumen distal end, with a hollow intermediate region between the two ends having one or more openings at the inner lumen distal end, and at least one inner lumen connector unit at the inner lumen proximal end; the dual lumen cannula has at least one outer lumen, the at least one outer lumen cannula having two ends, an outer lumen proximal end and an outer lumen distal end, with a hollow intermediate region between the two ends having one or more openings, the intermediate region further having one or more openings at the outer lumen distal end, and the at least one outer lumen cannula having at least one outer lumen connector unit at the outer lumen proximal end; and the dual lumen cannula has at least one flow router. The outer lumen is first inserted into the patient's body, and only then is the inner lumen inserted into the patient's body through the outer lumen until the inner lumen connector unit matingly connects with the outer lumen connector unit.

Description

[Technical Field]

[0001] Related Applications This application claims priority to U.S. Provisional Patent Application No. 63 / 111,803, entitled "Dual Lumen Cannula," filed November 10, 2020, and U.S. Provisional Patent Application No. 63 / 111,813, entitled "Dual Lumen Cannula," filed November 11, 2020, the contents of each of which are incorporated by reference as if fully set forth herein.

[0002] FIELD OF THE INVENTION The present invention relates generally to a dual lumen cannula assembly, and more particularly, to a dual lumen cannula in which the outer and inner lumens are connected in real time within the body and have opposite flow directions through a novel flow router connector. [Background technology]

[0003] Background of the Invention Medical procedures requiring extracorporeal treatment of blood, such as dialysis and extracorporeal oxygenation, require separate tubing for the removal of untreated blood from the body and the reinsertion of treated blood back into the body. There are two commonly practiced techniques for implementing such tubing into the vascular system—single-lumen cannulas and dual-lumen cannulas. Both of these techniques present significant challenges.

[0004] The use of two single-lumen cannulas is undesirable because they require two separate incision sites. The use of multiple incision sites causes patient discomfort and increases the risk of infection, especially for procedures in which the cannulas are retained in the body for hours or days. Furthermore, the medical team must insert the tubes twice, thus doubling the risks and the time required for this stage of the procedure.

[0005] The use of dual-lumen cannulas is also challenging for a number of reasons. One particular challenge relates to the manner in which they are inserted and primed. Typically, dual-lumen cannulas are inserted as standalone devices, with the distal end within the vascular system and the proximal end outside the body. The proximal end includes two tubes that may branch into a Y-shape. Once the dual-lumen cannula is fully inserted into the vein, each lumen at the proximal end of the dual-lumen cannula is then connected to separate tubing. This connection process requires the exertion of considerable force on the dual-lumen cannula, increasing the risk of vascular perforation. Furthermore, care must be taken during the connection of each lumen to the tubing to ensure that air bubbles do not enter the vascular system. This is typically accomplished by flushing the open end of each line with saline. Despite extensive training received by practitioners, preventing air bubbles from entering the bloodstream remains extremely difficult. The introduction of air bubbles would result in the formation of emboli which could potentially be fatal.

[0006] There have been several attempts in the art to use dual lumen cannulas. The following references may be considered relevant to the field of the present invention: U.S. Patent Application No. 2021023336, U.S. Patent No. 5,053,004, and U.S. Patent No. 5,718,678. Summary of the Invention

[0007] Summary of the Invention In one principal aspect, the present invention provides a dual-lumen cannula consisting of an outer lumen and a separate inner lumen that is assembled into the dual-lumen cannula in vivo in real time upon insertion of the inner lumen into an outer lumen that is initially inserted into a patient's body in a simple, standard procedure as a single-lumen cannula. Both lumens are assembled within the patient's body by a novel connector assembly, as described in detail below, that further determines the flow direction in each lumen of the dual-lumen cannula. The outer and inner lumens are preferably reversibly connected by the novel connector assembly, which allows for opposite flow directions within the outer and inner lumens of the dual-lumen cannula while one cannula is inserted within the other cannula.

[0008] In accordance with the present invention, the outer lumen cannula is inserted into the patient's vascular system by exerting minimal force on the cannula when it is positioned within the patient's vascular system as a single lumen cannula. Intubation of the outer cannula is preferably performed by standard intubation procedures.

[0009] When the outer lumen is positioned within the patient's body, the inner lumen is first connected to a desired device or system (such as, but not limited to, a blood treatment system) and primed, ready to be inserted into the outer lumen.

[0010] Accordingly, in one principal aspect, the present invention relates to a dual lumen cannula having: at least one inner lumen having at least two ends, an inner lumen proximal end and an inner lumen distal end, a hollow intermediate region between the two ends with one or more openings at the inner lumen distal end, and at least one inner lumen connector unit at the inner lumen proximal end; at least one outer lumen having at least two ends, an outer lumen proximal end and an outer lumen distal end, a hollow intermediate region between the two ends with one or more openings, the intermediate region further having one or more openings at the outer lumen distal end, and the at least one outer lumen having at least one outer lumen connector unit at the outer lumen proximal end; and at least one flow router; the inner lumen configured to be inserted into the outer lumen until the inner lumen connector unit couples with the outer lumen connector unit. The flow router connects to the inner lumen connector unit, and the connection from the flow router to one or more medical devices is preferably, but not necessarily, collinear with the inner and outer lumens. The intermediate region of the inner lumen further has one or more holes disposed within a region of the inner lumen between the distal and proximal ends of the outer lumen that is within the outer lumen when assembled. The outer lumen preferably has a narrow region at its distal end to center the position of the inner lumen at the target area. The opening on the intermediate region of the outer lumen is at least one discharge opening.

[0011] Upon connection of the outer lumen connector unit to the inner lumen connector unit, the inner lumen connector unit provides a flow path from the flow router to both the outer lumen and the inner lumen. The flow router further has an inlet port for connection to one or more connector tubing connected to at least one medical device.

[0012] The outer lumen may further include at least one suture element that allows for securing the outer cannula to the patient's body once intubated, and may further include one or more calibration marks.

[0013] The flow routers of the dual lumen cannulas provided herein may further include a first internal flow channel location connection region leading from the outer cannula through the outer lumen connector unit and then through the inner lumen connector unit to the medical device. In some other embodiments, the flow router further includes a second internal flow channel leading from the medical device through the inner lumen connector unit to the inner lumen.

[0014] In yet some other embodiments of the invention, blood flow is reversed and a first internal flow channel provides a flow path from the medical device through the inner lumen connector unit to the outer lumen connector unit and then to the outer lumen. Alternatively, blood flow is reversed and a second internal flow channel provides a flow path from the inner cannula through the inner lumen connector unit to the medical device.

[0015] In some optional embodiments, the outer lumen connector unit further comprises one or more barbs.Optionally, the outer lumen and the outer lumen connector unit may be formed as a single piece.

[0016] In some optional embodiments, the inner lumen connector unit further includes one or more flexible connectors for connecting to and sealing to one or more barbs from the outer lumen connector unit.

[0017] In some optional embodiments, the inner lumen connector unit further has a vertical dividing wall and chambers to create separate flow channels leading to the inner lumen through one or more lumen openings and through the outer lumen connector unit to the outer lumen.

[0018] The present invention further relates to a method for introducing a cannula into a patient's vascular system, the method comprising at least the following steps: inserting a first outer lumen cannula into the patient's vascular system through the use of an introducer (and optionally a guidewire) drawn through the outer lumen to its distal end; withdrawing the introducer and guidewire, causing a small vacuum to be created in the outer lumen, which refills with blood; priming a second inner lumen cannula through the use of a priming cap connected to a priming system, the priming cap being removed following completion of priming; and inserting the second inner lumen cannula into the first outer lumen cannula until the inner lumen connection unit is attached to the outer lumen connection unit.

[0019] The first outer lumen cannula may be sutured to the patient's skin by sewing a regular suture through the butterfly. Optionally, one or more flow routers are connected to the inner lumen connection unit, and medical devices are connected to the flow routers. [Brief explanation of the drawings]

[0020] Examples illustrating embodiments of the present disclosure are described below with reference to the accompanying drawings. Dimensions of components and features shown in the drawings are generally chosen for convenience and clarity of presentation and are not necessarily drawn to scale. Many of the drawings presented are in schematic form, and as such, certain elements may be greatly simplified or not drawn to scale for clarity of illustration. The drawings are not intended to be production drawings.

[0021] The drawings (figures) are listed below.

[0022] [Figure 1A] FIG. 1A is an isometric view of at least one embodiment of an innovative dual lumen cannula in an assembled and ready-to-use configuration having an exhaust outer lumen and an infusion inner lumen connected therethrough by a connector assembly, according to an optional embodiment of the present invention. [Figure 1B] FIG. 1B is a schematic side view of at least one embodiment of the outlet outer lumen of the dual lumen cannula of FIG. 1A, according to some optional embodiments of the present invention. [Figure 1C] FIG. 1C is a schematic isometric view of at least one embodiment of an infusion inner lumen of the dual lumen cannula of FIG. 1A, according to some optional embodiments of the present invention. [Figure 1D] FIG. 1D is a schematic isometric partial view of a connection region between the inner and outer lumens of the dual lumen cannula of FIG. 1A, according to some optional embodiments of the present invention. [Figure 1E] FIG. 1E is a schematic cross-sectional partial view of a connection region between the inner and outer lumens of the dual lumen cannula of FIG. 1A including a flow lumen connector, according to some optional embodiments of the present invention. [Figure 2A]FIG. 2A is an isometric view of at least one alternative embodiment of an innovative dual lumen cannula in an assembled and ready-to-use configuration having an exhaust outer lumen and an infusion inner lumen connected therethrough by a connector assembly, according to an optional embodiment of the present invention. [Figure 2B] 2B is a schematic isometric close-up view of the distal end of the outer drainage cannula of the dual lumen cannula of FIG. 2A and the overlapping region of the inner infusion cannula extending from the outer cannula. [Figure 3A] 3A-3B are schematic plan and isometric views, respectively, of the outlet outer lumen of the dual lumen cannula of FIG. 2A, according to some optional embodiments of the present invention. [Figure 3B] 3A-3B are schematic plan and isometric views, respectively, of the outlet outer lumen of the dual lumen cannula of FIG. 2A, according to some optional embodiments of the present invention. [Figure 4A] 4A-4B are schematic isometric back and side views of the infusion inner lumen of the dual lumen cannula of FIG. 2A, according to some optional embodiments of the present invention. [Figure 4B] 4A-4B are schematic isometric back and side views of the infusion inner lumen of the dual lumen cannula of FIG. 2A, according to some optional embodiments of the present invention. [Figure 5A] FIG. 5A is a schematic exploded view of the dual lumen cannula of FIG. 2A showing the major components of the dual lumen cannula of the present invention. [Figure 5B] 5B-5C are schematic back and front isometric partial views of a connection region between the inner and outer lumens of the dual lumen cannula of FIG. 2A, according to some optional embodiments of the present invention. [Figure 5C] 5B-5C are schematic back and front isometric partial views of a connection region between the inner and outer lumens of the dual lumen cannula of FIG. 2A, according to some optional embodiments of the present invention. [Figure 6A]6A-6B are schematic plan and cross-sectional partial views of a connection region between the inner and outer lumens of the dual lumen cannula of FIG. 2A including a flow router connector, according to some optional embodiments of the present invention. [Figure 6B] 6A-6B are schematic plan and cross-sectional partial views of a connection region between the inner and outer lumens of the dual lumen cannula of FIG. 2A including a flow router connector, according to some optional embodiments of the present invention. [Figure 6C] 6C-6D are schematic isometric and cross-sectional views, respectively, of a connector unit and flow router of the inner lumen cannula of the dual lumen cannula of FIG. 2A, according to some optional embodiments of the present invention. [Figure 6D] 6C-6D are schematic isometric and cross-sectional views, respectively, of a connector unit and flow router of the inner lumen cannula of the dual lumen cannula of FIG. 2A, according to some optional embodiments of the present invention. [Figure 6E] 6E-6F are schematic isometric front and rear views, respectively, of a connector unit and flow router of the inner lumen cannula of the dual lumen cannula of FIG. 2A, according to some optional embodiments of the present invention. [Figure 6F] 6E-6F are schematic isometric front and rear views, respectively, of a connector unit and flow router of the inner lumen cannula of the dual lumen cannula of FIG. 2A, according to some optional embodiments of the present invention. [Figure 6G] FIG. 6G is a schematic isometric side view of the flow router of FIG. 2A in a position that mimics the position of the unit during use with a dual-lumen cannula of the present invention, with the flow router housing transparent to show the internal components, according to some optional embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] Detailed Description of Embodiments of the Invention In the following description, various aspects of the novel single dual lumen cannula and flow router connector will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the present invention.

[0024] Although various features of the present disclosure will be described in the context of a single embodiment, the features may also be provided separately or in any suitable combination. Conversely, although the present disclosure will be described in the context of separate embodiments for clarity, the present disclosure may also be implemented in a single embodiment. Furthermore, it should be understood that the present disclosure can be practiced or implemented in various ways and that the present disclosure can be implemented in embodiments other than the exemplary embodiments described herein below. The descriptions, examples, and materials presented in the specification and claims should be construed as illustrative, not limiting.

[0025] In one primary aspect, the present invention aims to provide a convenient and safe solution that allows practitioners to insert a dual-lumen cannula as simply and safely as inserting a single-lumen cannula. Aside from the simplicity of cannulating the cannula into the target area and the benefits to the medical team, the novel solution also benefits the patient, since it allows the second lumen to be threaded in vivo through the first lumen, one into the other, after insertion of the first single lumen, without the need to create an additional incision in the entry area, as is required when using conventional dual-lumen cannulas, thus avoiding the inconvenience, potential contamination, and additional scarring that would otherwise occur for the patient. Both lumens are connected in vivo by a unique and novel connector assembly that connects the two lumens and is further configured to provide countercurrent flow in the inner and outer lumens. Thus, the outer lumen is inserted into the patient's vascular system, and the inner lumen is inserted through the outer lumen to the desired location.

[0026] As used herein, the term "cannula" refers to a thin tube that is inserted into a blood vessel to allow blood to be extracted from or injected into the vessel. A "dual-lumen cannula" in the disclosed embodiments is a cannula that includes an inner lumen surrounded by an outer lumen, thus allowing simultaneous, physically separate inflow and outflow of blood through a single dual-lumen cannula inserted into a patient's vascular system.

[0027] The term "proximal" refers to a direction closer to the blood treatment system or any other machine to which the dual lumen cannula is connected, and the term "distal" refers to a direction toward or within the patient's body / vascular system.

[0028] The term "lumen" refers to the interior space in a tube for the transport of liquids or gases.

[0029] The term "drain lumen" or "outer lumen" refers to a lumen that drains or transports blood from a subject's body into the machine prior to treatment. In the following description, the terms "outer lumen," "outer cannula," "outer drain cannula," "drain cannula," and "drain lumen" are all used interchangeably and refer to the same component.

[0030] The term "infusion lumen" or "inner lumen" refers to the lumen that infuses blood from the machine back into the body after treatment. In the following description, the terms "inner lumen," "inner cannula," "inner infusion cannula," "infusion cannula," and "infusion lumen" are all used interchangeably and refer to the same component.

[0031] Although the description herein refers to the outer lumen as an evacuation lumen and the inner lumen as an infusion lumen, in some other optional embodiments and implementations of the invention, the outer lumen may be used to infuse blood into the body and the inner lumen may be used to drain blood from the body.

[0032] Additionally, although reference is made to the drainage and infusion of blood, it should be clear that other bodily fluids may also be drained and infused with the novel dual lumen cannula provided herein, and the present invention is not limited in any way to blood.

[0033] Reference is now made to the drawings.

[0034] 1A is a schematic isometric view of a dual-lumen cannula 100 of the present invention in an assembled and ready-to-use configuration. In this configuration, dual-lumen cannula 100 has an outlet outer lumen configured to drain blood drained from the body of a treated patient through outlet opening 112 of cannula 106 toward an extracorporeal machine for treatment, and an infusion inner lumen configured to infuse blood from the extracorporeal machine back into the body of a treated patient through infusion opening 122 of cannula 127, the inner and outer lumens connected to one another by a connector assembly, described in detail below, which connects the two lumens and conducts blood flow through each of them.

[0035] The outer lumen cannula 106 may have calibration marks 190 to provide the medical team with an indication of the penetration length. In a similar manner, the inner lumen cannula 127 may also contain calibration marks 190 for monitoring the penetration length of the inner lumen.

[0036] The inner lumen has a connector unit 132, which is preferably, but not necessarily, an integral part of the inner lumen. Optionally, the connector unit 132 is connected to a butterfly 116 having suture holes that may be secured to the patient's skin using standard sutures to stabilize the position of the dual lumen cannula during the medical procedure. It should be apparent that other means for stabilizing and attaching the cannula to the patient's body may be used, and that the butterfly 116 is merely one non-limiting, exemplary implementation.

[0037] The connector unit 132 of the inner lumen is operatively connected at its proximal end to a connector unit 136 (hereinafter also referred to as "flow router" 136). The flow router 136 is a connection unit between the dual-lumen cannula and an extracorporeal machine, and is configured and operable to establish counter-directional blood flow between the inner and outer lumens, and preferably from flow in two separate parallel tubes to flow within the two insertable lumens entering the other lumen. The connector unit 132 is further connected to the connection configuration of the cannula 106, as described below with reference to FIGS. 1C-1D. The connection between the inner and outer lumens is performed in vivo within the patient's body, as the outer lumen is first inserted into the patient as a single-lumen cannula, and only then is the inner lumen threaded into the outer lumen until they join to form a dual-lumen cannula. Also shown in this figure is the tubing connection platform 50, which is one of two tubing connector platforms that connect to the flow router 136 and allow connection of the dual lumen cannula of the present invention to tubing for transporting blood from the patient's body to the extracorporeal machine and for transporting blood in the reverse direction from the extracorporeal machine to the patient's body.

[0038] FIG. 1B is a schematic side view of the discharge outer lumen 110 of the dual-lumen cannula of FIG. 1A , according to some optional embodiments of the present invention. In this embodiment, the outer lumen 110 has at least a cannula 106 (also interchangeably referred to as an “inner cannula” and an “infusion cannula”) having a diameter larger than that of the inner lumen 120, thereby allowing insertion of the inner lumen 120 therethrough. The cannula 106 has a narrow region 111 at its distal end for focusing the position of the inner lumen primarily toward the target area, and has at least one discharge opening 112. Optionally, the cannula 106 contains calibration marks 190, which may further be marked with numbers, to indicate the penetration length of the outer lumen 110 into the patient's body. The cannula 106 has a connector unit 108 at its proximal end. In the particular example shown herein, connector unit 108 is made with trailing barbs that continue into cannula 106. Upon connection of the inner lumen to the outer lumen, connector unit 108 is configured to be inserted into a complementary niche or socket in the inner lumen connector unit, as described with reference to Figures 1C-1D. Other connection solutions, such as luer locks, snap connections, etc., may alternatively be used.

[0039] 1C is a schematic isometric view of the infusion inner lumen 120 of the dual-lumen cannula of FIG. 1A , according to some optional embodiments of the present invention. The inner lumen cannula 120 includes a cannula 127 and an inner lumen connector unit 132, which in the example shown herein is connected to a flow router 136 and is connected as one piece to the proximal end of the cannula 127. The cannula 127 has a smaller diameter relative to the cannula 106, operatively allowing it to be threaded through the cannula 106, and a greater length, allowing it to extend beyond the cannula 106 to the target area. The cannula 127 has at least one infusion opening 122 at its distal end, which allows treated blood to be returned from the extracorporeal machine to the patient's vascular system. The cannula 127 may further include a pressure adjustment hole 128 formed along the circumference of the inner lumen. The pressure adjustment hole 128 is positioned along the cannula 127 so that when the inner lumen 120 is inserted into the outer lumen 110, the pressure adjustment hole 128 is covered by the outer lumen 110. The pressure adjustment hole 128 functions to alleviate high-pressure conditions in the infusion lumen that would otherwise result in cavitation. Cavitation is a phenomenon in which a sudden change in pressure in a liquid results in the formation of small vapor-filled cavities where the pressure is relatively low. Cavitation in a blood vessel would cause the formation of liquid jets and, in some cases, vessel rupture. The dimensions of the hole 128 are determined so that when the pressure in the inner lumen 120 increases above a predetermined level, blood passes from the inner lumen to the outer lumen through the pressure adjustment hole 128, thereby bypassing the patient's vascular system. In such a situation, blood will flow into the hole 128 based on the principle of fluid dynamics that liquids always follow the path of least resistance. Blood continues to flow through holes 128 until the pressure in infusion lumen 120 drops to a point where infusion lumen 120 again becomes the path of least resistance. Connector unit 132 may have butterfly 116 with suture holes to allow the dual lumen cannula of the present invention to be sewn to a patient's skin during a medical procedure.

[0040] Also shown in this figure are tubing connection platforms 50 and 50', which connect outer tubing to the inner and outer lumens, respectively, to allow drained blood to flow into the machine and blood to flow from the machine back into the patient's vascular system. The inner lumen 120 may also have a priming cap (not shown) at its distal end. The priming cap may be removable and connected to a priming system for priming the inner lumen 120. For example, the priming cap may be connected to a source of saline and removed after priming is complete.

[0041] Proximal to the priming cap, inner lumen 120 has infusion openings 122 for fluid connection to the patient's vascular system. These openings provide a path for the flow of treated blood back into the cardiovascular system. Also shown in these figures are calibration marks 190 and tubing 50 and 50' that transport blood into and out of the medical machine.

[0042] 1D is a schematic isometric partial view of the connection region between inner lumen 120 and outer lumen 110 of dual lumen 100 of FIG. 1A, according to some optional embodiments of the present invention. In this view, cannula 127 is connected at its proximal end to inner lumen connector unit 132 and inserted through its distal end into the proximal end of cannula 106 through outer connector unit 108. Connector unit 108 is then pushed into the interior space of inner lumen connector unit 132 so that its barbs are engaged and covered by connector unit 132.

[0043] FIG. 1E is a schematic cross-sectional partial view of a connection region between inner lumen 120 and outer lumen 110 of dual lumen cannula 100 of FIG. 1A including a flow router connector, according to some optional embodiments of the present invention.

[0044] The cross-sectional partial view shows the opposite flow directions of drained and infused blood in the infusion inner cannula 127 and the drain outer cannula 106. For simplicity of illustration, the outer lumen cannula connector unit 108 and the inner lumen cannula connector unit 132 are separated to clearly show the components involved in the connection. Blood flow begins only when the two cannulae are connected and the barb 108 is pushed into and hooked onto the distal end of the connector unit 132. During connection of the two lumens, the cannula 106 surrounds the cannula 127 inserted therein. Blood flow in both lumens and the connector units 131 and 132 is performed in parallel lumens and in opposite directions, as indicated by the arrows along the two cannulae. The flow router 136 collects the drained blood entering the chamber 1326 into one tube that will be connected to the tube connector platform 50 and transports the blood into the extracorporeal machine for treatment. In the same manner, but in the reverse direction, the treated blood from the extracorporeal machine is infused back into the vascular system of the patient being treated through a tube that will be connected to the tube connector platform 50', transporting the treated blood through the flow router 136 towards the cannula 127 and toward the patient's body.

[0045] 2A is a schematic isometric view of a dual-lumen cannula 200 of the present invention in an assembled, ready-to-use configuration. In this configuration, dual-lumen cannula 200 has an outlet outer lumen with cannula 106 configured to drain blood drained from the body of a treated patient through outlet opening 112 toward a machine for treatment, as described in detail below, and an infusion inner lumen with cannula 127 configured to infuse blood from the machine back into the body of a treated patient through infusion opening 122, the inner and outer lumens connected to one another by a connector assembly that connects the two lumens and routes blood flow in each of them.

[0046] Optionally, cannulae 106 and 127 have calibration marks 190, thereby providing the medical team with an indication of the penetration length. The outer lumen has an outer connector unit 131 at its proximal end, which is preferably, but not necessarily, an integral part of connector assembly 130 and is configured to allow physical connection of the outer lumen with the inner lumen. The outer lumen may optionally contain a butterfly 116 with suture holes that can be secured to the patient's skin using standard sutures to allow fixation of the outer cannula to the patient's body and stabilize its position prior to insertion of the inner cannula therethrough. In this particular example, connector unit 131 is the connector to butterfly 116. It should be apparent that other means of stabilizing and attaching the outer cannula to the patient's body are also within the scope of the present invention, and the example provided herein is merely one illustrative, optional implementation.

[0047] Also shown in this figure is inner lumen connector unit 132, which is preferably, but not necessarily, an integral part of the inner lumen. When threading the inner lumen into the outer lumen, outer lumen connector unit 131 and inner lumen connector unit 132 are coupled as described in detail with reference to FIGS. 5A-5B. Also shown in this figure is flow router 136, which is a connection unit between the dual-lumen cannula and an extracorporeal machine and is configured and operable to establish reverse blood flow between the inner and outer lumens. Connector units 131, 132, and 136 together constitute connector assembly 130. Also shown in this figure is tubing connection platform 50, which serves the same purpose as described above with reference to FIG. 1A.

[0048] FIG. 2B is a schematic isometric close-up view of the overlapping region of the inner infusion cannula 127 extending out from the distal end of the outer drain cannula 106 and the distal tip of the outer cannula 106 of the dual-lumen cannula of FIG. 2A. As shown in this figure, the distal tip of the outer cannula 106 is narrow relative to the diameter of the outer lumen dimensions in other regions. This narrow region 111 at the distal end of the outer cannula 106 forces the inner cannula 127 to converge as it passes through it toward the target area within the patient's body. The inner cannula 127 is preferably longer than the outer cannula 106 in a manner that allows treated blood to be infused through the infusion opening 122 away from the blood ejected through the drain opening 112. The distance that the inner cannula 127 extends beyond the outer cannula 106 is preferably a fixed length. This view also shows calibration marks 190 on both outer cannula 106 and inner cannula 127. Calibration marks are only optional features, and other means for estimating penetration length may be used. This view also shows pressure adjustment hole 128 located on inner lumen 120.

[0049] 3A-3B are schematic plan and isometric views, respectively, of the discharge outer lumen 110 of the dual-lumen cannula 200 of FIG. 2A , according to some optional embodiments of the present invention. The outer lumen 110 includes at least a cannula 106 having a fixed diameter larger than the diameter of the inner lumen 120, thereby enabling insertion of the inner lumen 120 therethrough. The cannula 106 has a narrow region 111 at its distal end for primarily focusing the position of the inner lumen toward the target area, and has at least one discharge opening 112. Optionally, the cannula 106 includes calibration marks thereon, which may further be numbered, to indicate the penetration length of the outer lumen 110 into the patient's body. The cannula 106 is attached at its proximal end to an outer connector unit 131 having at least two protruding elements 1312 configured to be inserted into complementary niches or sockets in the inner lumen connector unit 132 of the inner lumen 120 in the particular example shown herein. Other connection solutions such as luer locks, barbs, snap connections, etc. may alternatively be used. In some optional embodiments, outer lumen 110 further includes a suturing element that secures outer cannula 110 to the patient's body once it is intubated, ensuring minimal movement and unwanted withdrawal of the cannula from the patient's body. Securing the inner cannula within the body before inserting it through the outer drainage cannula further ensures a steady drainage of blood from, and a steady infusion of blood back into, the patient's body.

[0050] 4A-4B are schematic isometric back and side views of the infusion inner lumen 120 of the dual-lumen cannula 200 of FIG. 2A , according to an optional embodiment of the present invention. In these figures, the inner lumen connector unit 132 and the flow router 136 are attached to one another and connected to the proximal end of the cannula 127 as one piece. The cannula 127 has a smaller diameter relative to the cannula 106, operatively allowing it to be inserted through the cannula 106, and a greater length, allowing it to extend beyond the cannula 106 to the target area. The cannula 127 has at least one infusion opening 122 at its distal end, allowing treated blood to be returned from the extracorporeal machine to the patient's vascular system. The cannula 127 further has pressure adjustment holes 128 formed along the circumference of the inner lumen. The pressure adjustment hole 128 is positioned along the cannula 127 so that when the inner lumen 120 is inserted into the outer lumen 110, the pressure adjustment hole 128 is covered by the outer lumen 110. The pressure adjustment hole 128 functions to alleviate high-pressure conditions in the infusion lumen that would otherwise result in cavitation. Cavitation is a phenomenon in which a sudden change in pressure in a liquid results in the formation of small vapor-filled cavities where the pressure is relatively low. Cavitation in a blood vessel would cause the formation of liquid jets and, in some cases, vessel rupture. The dimensions of the hole 128 are determined so that when the pressure in the inner lumen 120 increases above a predetermined level, blood passes from the inner lumen to the outer lumen through the pressure adjustment hole 128, thereby bypassing the patient's vascular system. In such a situation, blood will flow into the hole 128 based on the principle of fluid dynamics that liquids always follow the path of least resistance. Blood continues to flow through holes 128 until the pressure in infusion lumen 120 drops to a point where infusion lumen 120 again becomes the path of least resistance.

[0051] Also shown in these figures are tubing connector platforms 50 and 50' that allow the extensions of the inner and outer lumens to be connected to tubing for transporting drained blood into the machine and back from the machine into the patient's vascular system. The inner lumen 120 may further have a priming cap (not shown) at its distal end. The priming cap may be removable and connected to a priming system for priming the inner lumen 120. For example, the priming cap may be connected to a source of saline and removed after priming is complete.

[0052] Proximal to the priming cap, inner lumen 120 has infusion openings 122 for fluid connection to the patient's vascular system. These openings provide a path for the flow of treated blood back into the cardiovascular system. Also shown in these figures are calibration marks 190 and tubing connector platforms 50 and 50' for transporting blood into and out of the medical machine.

[0053] 5A is a schematic exploded view of the dual lumen cannula 200 of FIG. 2A, showing the main components of the device. As shown in this drawing, dual lumen cannula 200 consists of three main functional components: outer lumen 110, inner lumen 120, and flow router 136, which has tube connection platforms 50 and 50′ at its proximal end, thereby enabling the transport of blood into and out of the medical machine.

[0054] In some preferred embodiments of the present invention, the flow router 136 is an integral part of the inner lumen connector unit 132, and both are connected to the outer end of the lumen as one unit to create the inner lumen 120. As shown in this figure, the inner lumen, together with the inner lumen connector unit 132, and optionally also with the connector unit 136, is designed to be passed through a pre-cannulated outer lumen 110 into the patient's body as a single-lumen cannula. Also shown in this figure are three connector units with connection elements between them. These elements will be described in detail below. However, the connection elements described herein should be construed as one non-limiting implementation of the present invention, as other connection means are also optional embodiments that may be implemented to connect between the connector assembly units of the present invention. The following elements are also shown in this figure:

[0055] For outer lumen cannula 110: outer connector unit 131, protruding element 1312, cannula 106, calibration mark 190, discharge opening 112, narrow area 111 of the outer cannula and butterfly 116 with suture holes.

[0056] For inner lumen cannula 120: inner lumen connector unit 132, cannula 127, calibration mark 190, injection opening 122, pressure adjustment hole 128, vertical dividing wall 1324 and chamber 1326.

[0057] About the flow router 136: chamber 110', cannula 127. Also shown are tubes 50 and 50' that are not part of the flow router 136 but are connected to its openings.

[0058] All components and their functional roles are described below.

[0059] 5B-5C are schematic back and front isometric partial views of the connection region between inner lumen 120 and outer lumen 110 of dual-lumen cannula 200 of FIG. 2A , according to some optional embodiments of the present invention. In this view, cannula 127 is connected at its proximal end to inner lumen connector unit 132 and inserted through its distal end into the proximal end of outer connector unit 131 in a manner that allows protruding elements 1312 of outer connector unit 131 to surround cannula 127 and functionally create mechanical support, centralizing the position of cannula 127 within outer cannula 106 at its proximal end in addition to the narrowing structure of cannula 106 at its distal end. Protruding elements 1312 are then inserted into the interior space of inner lumen connector unit 132. In some optional embodiments of the present invention, cannula 127 extends into inner lumen connector unit 132 until it reaches its proximal end. In such a scenario, the cannula 127 is connected to the outer periphery of the inner lumen connector unit 132 by at least one vertical dividing wall (septum) 1324. In the particular example shown in this figure, the inner lumen connector unit 132 contains four dividing walls 1324, and drained blood flows from the patient's vascular system through the outer lumen 110 into a chamber 1326 created between the dividing wall 1324 and the cannula 127, while infused blood flows back to the body via the lumen (opening) 1270 of the cannula 127. Also shown in these figures is a butterfly 116 (also referred to as a "suture element") with suture holes that can be used to secure the outer cannula 110 to the patient's skin using standard sutures for safer use of the dual-lumen cannula 200 of the present invention. As noted above, other attachment means, such as rubber bands, external fixation devices, and the like, may additionally or alternatively be used.In some other optional embodiments of the present invention, inner cannula 127 extends only to the distal end of inner lumen connector unit 132, and a central hollow tube-like structure within connector unit 132 acts as an extension of and replaces inner cannula 127.

[0060] 6A-6B are schematic plan and cross-sectional partial views of the connection region between inner lumen cannula 120 and outer lumen cannula 110 of dual lumen cannula 200 of FIG. 2A. Outer connector 131 is attached at its distal end to cannula 106 and at its bottom side to suturing element 116. Outer connector unit 131 has protruding elements 1312 on its proximal side ready to be inserted into complementary spaces within inner lumen connector unit 132 and surrounds cannula 127 of inner lumen cannula 120. Also shown in these figures is flow router connector 136, which is attached to inner lumen connector unit 132. As previously mentioned, flow router 136 should be considered the third connector unit of the connector assembly of the present invention and may be a separate unit or an integrated unit of inner lumen connector unit 132. In scenarios where flow router 136 is a separate, independent unit, it may be assembled with inner lumen connector unit 132 by any suitable connecting means known in the art. For example, an operator may snap one into the other, lock them with a luer lock, or attach one to the other by using, for example, an attachment ring or the like. Infused and drained blood is transported from the machine to and from the patient's body by tubing (not shown) connected to tubing connector platforms 50 and 50' that extend from flow router 136 toward the extracorporeal machine.

[0061] The cross-sectional partial view shows the opposite flow directions of drained and infused blood in the inner infusion cannula 120 and outer drainage cannula 110. For simplicity of illustration, the outer lumen cannula connector unit 131 and the inner lumen cannula connector unit 132 are separated to clearly show the connecting components. Blood flow begins only when the two cannulae are joined. This cross section also shows cannula 106 surrounding cannula 127. Blood flow in both lumens and connector units 131 and 132 is parallel and in opposite directions, as indicated by the arrows along the cannulae. Flow router 136 collects all drained blood entering chamber 1326 into a single tube that will connect to tube connector platform 50 and transport the blood into an extracorporeal machine for treatment. In the same manner but in the reverse direction, treated blood from the extracorporeal machine is infused back into the vascular system of the patient being treated through tubing that is connected to the tubing connector platform 50' and transports the treated blood through the flow router 136 and into the cannula 127 toward the patient's body.

[0062] 6C-6D are schematic isometric and cross-sectional views, respectively, of inner lumen connector unit 132 and flow router 136 of dual-lumen cannula 200 of FIG. 2A , according to some optional embodiments of the present invention. Flow router 136 collects drained blood from outer tube 110 through different chambers 1326 of inner lumen connector unit 132 into a single tube connected to tube connector platform 50, which transports the drained blood into an extracorporeal machine. Flow router 136 also routes blood from the extracorporeal machine through tubes connected to tube connector platform 50′ in a manner such that blood entering two separate adjacent tubes is converted to enter two lumens (one inserted inside the other) while maintaining the opposite flow direction.

[0063] In the isometric view ( FIG. 6C ), the inner lumen connector unit 132 and flow router 136 are connected to one another, and the tube connector platforms 50 and 50′ are partially shown at the proximal end of the flow router 136. The isometric view further shows the cannula 127 and lumen 1270, dividing wall 1324, chamber 1326, and region 131′ where the outer connector unit 131 with protruding element 1312 is connected, shown at the distal end of the inner lumen connector unit 132. The cross-sectional view ( FIG. 6C ) shows the flow of treated blood within the cannula 127 from a tube connected to the tube connector platform 50′ toward the patient's vascular system. In the reverse direction, drained blood exiting the body through the outer lumen 110 enters chamber 1326 of the inner lumen connector unit 132, which functionally acts as an extension of the outer lumen 110 to transport the drained blood from the body to an extracorporeal machine via a tube configured to be connected to the tube connector platform 50. Blood from chambers 1326 is preferably collected into a single chamber 110' connected at its proximal end to a tubing connector platform 50 that transports the discharged blood within flow router 136 into tubing connected to an extracorporeal machine.

[0064] The extracorporeal machines that may be implemented with the dual lumen cannulae 100 and 200 of the present invention are preferably extracorporeal oxygenation systems and dialysis systems.

[0065] 6E-6F are schematic isometric front and isometric back views, respectively, of inner lumen connector unit 132 and flow router 136 of inner lumen cannula 120 of dual-lumen cannula 200 of FIG. 2A , according to some optional embodiments of the present invention. The isometric view ( FIG. 6E ) clearly shows four chambers 1326 created at the interface of dividing wall 1324 and cannula 127. Blood drained from the patient's body is transported through these chambers to the extracorporeal machine, and returning blood to be infused back into the patient's vascular system flows within lumen 1270 of cannula 127 until it reaches infusion opening 122 and is infused back into the body. The isometric rear view (FIG. 6F) shows the connection of the flow router 136 to the tubing connector platforms 50 and 50′, which transport blood drained from the body through the cannula 106, through the outlet opening 112 of the outer lumen, into the chamber 1326 of the inner lumen connector unit 132, all of which is collected into a single chamber 110′ of the flow router 136 and connected to the tubing connector platform 50 for transport to tubing (not shown) and into the extracorporeal machine. The rear view also shows the entry point for treated blood from the extracorporeal machine through tubing (not shown) connected to the tubing connector platform 50′ and then into the cannula 127, which extends from the proximal end of the flow router 136, through the inner lumen connector unit 132, and further through the outer connector unit 131 into the cannula 106 until it exits its distal end and extends to the target area. In fact, cannula 127 in this optional implementation of the invention passes through the entire unit of connector assembly 130 and through cannula 106 until it reaches the target area and injects blood through infusion opening 122. However, in some optional embodiments, inner cannula 127 may extend to the distal end of connector unit 132, and from such point into the tubing connected to tubing connector platform 50′, the treated blood flows through dedicated chambers within flow router 136 and connector unit 132 until it reaches inner cannula 127.

[0066] 6G is a schematic isometric side view of the flow router 136 of FIG. 2A in a position mimicking the position of the unit while a dual-lumen cannula is in use and connected to a patient's body, according to some optional embodiments of the invention (the housing of the flow router 136 is transparent, revealing the internal components). In this view, the tube connector platforms 50 and 50′ are positioned facing upward. As previously described, the tube connector platform 50′ in one optional embodiment is connected at one end to the cannula 127 and to a tube (not shown) that transports blood from the extracorporeal machine into the patient's body, while the tube connector platform 50 is connected at one end to the chamber 110′ and to a tube for transporting aspirated blood from the body into the extracorporeal machine at the other end. Also shown in this position are the connection region 1328 of the flow router 136 and the inner lumen connector unit 132, as well as the internal components of the flow router 136, including the cannula 127 and the chamber 110′.

[0067] In typical implementations of the dual-lumen cannulas 100 and 200 provided herein, the inner lumen is an infusion lumen for delivering treated blood back into the patient's vascular system, and the outer lumen is an exhaust lumen for removing untreated blood from the vascular system. However, in some other optional implementations of the present invention, the outer lumen may be used to return blood into the body, and the inner lumen is used to drain blood from the body. Furthermore, the inner lumen 120 has a longer extension than the outer lumen 110. An advantage of the inner lumen being longer than the outer lumen and being the infusion lumen is that treated blood accumulates in the vascular system downstream of the exhaust lumen. This orientation reduces the possibility of circulating treated blood from the infusion lumen 120 to the exhaust lumen 110 and back into the blood treatment system.

[0068] In an illustrative, non-limiting example, the inner lumen 120 is sized to be long and of sufficient diameter to be inserted into the femoral vein and / or into the superior vena cava via major veins above the heart, including, but not limited to, the left and right internal jugular veins, the left and right external jugular veins, and the left and right brachiocephalic veins. The dimensions of the inner and outer lumens may be determined by considerations such as the patient's size and the desired volume and flow rate of blood through the lumens. In an exemplary embodiment, the inner lumen 120 has a length of 10-40 mm and a diameter of 5-16 Fr, and the outer lumen 110 has a length of 10-40 mm and a diameter of 10-24 Fr.

[0069] The connection between the inner and outer lumens may be reversible, and they may be separate. Upon insertion of the inner lumen into the outer lumen, the position of one lumen relative to the other is fixed and predetermined by connector units each connected to a respective one of the cannulas.

[0070] It should be apparent to one skilled in the art that the connector assembly 130 is depicted schematically and that the connecting assembly, and each of its units and the connections therebetween, may take any other form suitable for converting inner and outer tubes into side-by-side tubing, so long as its function remains the same.

[0071] The outlet lumen 110 includes an opening 112 for drawing blood therethrough from the patient's vascular system. The opening 112 is an intake hole through which blood is drawn by the force of a pump that is part of the extracorporeal blood treatment machine. The opening 112 is preferably located at the distal end of the outlet lumen 110. In some embodiments, the opening 112 is sized and located to the distal end of the outlet lumen 110 to prevent blocking of the blood outlet during intake. Blockage may occur due to venous adhesion to the outlet lumen due to clotting or suction forces.

[0072] Introducing the dual-lumen cannula 100, 200 of the present invention into a patient's vascular system proceeds as follows: First, the outer lumen 110 is inserted into the patient's vascular system. The outer lumen may be sutured to the patient's skin by threading a conventional suture through the butterfly 116. Typically, the outer lumen is inserted through the use of an introducer and, optionally, through the use of a guidewire that is pulled through the outer lumen 110 to its distal end according to common practice (Seldinger technique). Consequently, there is no need to prime the outer lumen cannula before insertion, because the presence of the introducer prevents the formation of air bubbles. When the introducer and guidewire are withdrawn, the withdrawal causes a small vacuum to form in the outer lumen 110, which subsequently fills with blood.

[0073] Next, the inner infusion lumen 120 is preferably pre-primed through the use of a priming cap (not shown), which may be connected to a priming system. The priming system may be a stand-alone system or may be integrated with the extracorporeal blood machine. Following completion of priming, the priming cap is removed.

[0074] Next, the inner lumen 120 is inserted into the outer lumen 110 through the outer lumen connector unit (either 108 or 131). The inner lumen 120 is advanced to protrude through the outer lumen 110 until the connectors of each lumen interlock. The inner lumen 120 is secured to the outer lumen 110 when the connector assembly units are connected. Once the two lumens are connected, they function as a single dual-lumen cannula 100, 200.

[0075] Insertion of the inner lumen is performed with minimal discomfort to the patient. Furthermore, because inner lumen 120 is already fully primed prior to connection, there is no need to prime the open connection port during the connection process, as with other dual-lumen cannulas known in the art. Therefore, the intubation process for the dual-lumen cannula of the present invention is significantly easier and safer than intubation of other commercially available dual-lumen cannulas.

[0076] In particular, the described method is particularly advantageous over alternative dual-lumen cannula systems in which the two lumens are inserted as a separate, single unit and advanced to a desired location in the body while connected to one another before further advancement of the inner lumen relative to the outer lumen. Simultaneous movement of the inner and outer lumens would result in the application of greater force to the vessel and correspondingly require greater skill to perform without trauma to the patient. In contrast, when the outer lumen 110 is sutured in place prior to insertion of the inner lumen 120, it is only necessary to advance the inner lumen 120 relative to the outer lumen 110. Furthermore, insertion of the inner lumen separately from the outer lumen allows for pre-priming of the inner lumen prior to connection. After placement of the inner lumen cannula within the outer lumen cannula, a fluid-tight connection will be formed.

[0077] In some optional embodiments, the inner diameter of inner cannula 106 at its distal end is sized to be only slightly wider than the outer diameter of inner cannula 127. This sizing allows inner cannula 127 to slide freely through narrow region 111 while also minimizing inefficiencies resulting from blood flowing through narrow region 111 instead of continuing through outer cannula 127.

[0078] In the illustrated embodiment, the proximal point of connection between inner lumen 120 and outer lumen 110 is fixed. Thus, inner lumen 120 always extends a certain distance beyond outer lumen 110.

[0079] Preferably, the dual lumen cannula is designed to allow treated blood to circulate throughout the bloodstream after entering the body through the infusion lumen before the blood is removed through the outlet lumen.

[0080] It should be clear that the description of the embodiments set forth herein and the accompanying drawings only provide a better understanding of the present invention without limiting its scope. It should also be clear that a person skilled in the art, after reading this specification, may make adjustments or corrections to the accompanying drawings and the above-described embodiments that will still be covered by the present invention.

Claims

1. 1. A dual lumen cannula, the cannula comprising: at least one inner lumen having at least two ends, an inner lumen proximal end and an inner lumen distal end, a hollow intermediate region between the two ends having one or more openings at the inner lumen distal end, and at least one inner lumen connector unit at the inner lumen proximal end; at least one outer lumen, the at least one outer lumen having at least two ends, an outer lumen proximal end and an outer lumen distal end, with a hollow intermediate region between the two ends having one or more openings, the intermediate region further having one or more openings at the outer lumen distal end, and the at least one outer lumen having at least one outer lumen connector unit at the outer lumen proximal end; and having at least one flow router; the inner lumen is configured to be inserted into the outer lumen until the inner lumen connector unit matingly connects with the outer lumen connector unit; the flow router connects to the inner lumen connector unit; and the connections from the flow router to one or more medical devices are collinear with the inner lumen and the outer lumen. The cannula.

2. 2. The cannula of claim 1, wherein the intermediate region of the inner lumen further comprises one or more holes disposed within a region of the inner lumen between the distal end and the proximal end of the outer lumen and within the outer lumen when assembled.

3. 3. The cannula of claim 1, wherein the outer lumen further comprises a narrowed region at a distal end for concentrating the position of the inner lumen toward a target area.

4. The cannula of any one of claims 1 to 3, wherein the one or more openings on the intermediate region of the outer lumen is at least one exhaust opening.

5. 5. The cannula of claim 1, wherein when the outer lumen connector unit is connected to the inner lumen connector unit, the inner lumen connector unit provides a flow path from the flow router to both the outer lumen and the inner lumen.

6. The cannula of any one of claims 1 to 5, wherein said at least one flow router further comprises an inlet port (50) for connection to one or more connector tubing connected to at least one medical device.

7. The cannula according to any one of claims 1 to 6, wherein the outer lumen further comprises at least one suture element that allows the outer cannula to be fixed to the patient's body once intubated.

8. The cannula of any preceding claim, wherein the inner lumen or the outer lumen further comprises one or more calibration marks (190).

9. The cannula of any one of claims 1 to 8, wherein the flow router further comprises a first internal flow channel position connection region extending from the outer cannula through the outer lumen connector unit and then through the outer lumen connector unit to the medical device.

10. The cannula of any preceding claim, wherein the flow router further comprises a second internal flow channel leading from the medical device through the inner lumen connector unit to the inner lumen.

11. 11. The cannula of claim 9 or 10, wherein the flow is reversed to provide a flow path from the medical device through the inner lumen connector unit to the outer lumen connector unit and then to the outer lumen.

12. The cannula of claims 9-11, wherein the second internal flow channel reverses flow to provide a flow path from the inner cannula through the inner lumen connector unit to the medical device.

13. The cannula of any preceding claim, wherein the outer lumen connector unit further comprises one or more barbs.

14. The cannula of claim 13 , wherein the outer lumen and the outer lumen connector unit are formed as a single piece.

15. 15. The cannula of any preceding claim, wherein the inner lumen connector unit further comprises one or more flexible connectors for connecting to and sealing to one or more barbs from the outer lumen connector unit.

16. 15. The cannula of any one of claims 1 to 14, wherein the inner lumen connector unit further comprises a vertical separation wall and chambers for creating separate flow channels to the inner lumen through one or more lumen openings and to the outer lumen through the outer lumen connector unit.

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