Magnetic catheters, devices, use of magnetic catheters, and methods of use.

Abstract

A catheter is provided that can be used in conjunction with devices, systems, and methods to provide improved visualization of catheters and medical devices. [Solution] A catheter is provided that includes a polymer tube, at least a portion of which includes a magnetized portion that is magnetized to generate a known magnetic field B at a distance x through tissue of magnetic permeability μr, and the position of the catheter is detectable by a magnetometer based on the measured strength and direction of the known magnetic field and a correlation between the known magnetic field and the magnetic permeability of the tissue at a selected distance, the correlation being calculated as x=f(B,μr).

Description

Technical Field

[0001] The present disclosure relates to a magnetized polymer catheter that provides improved visualization of vascular access devices during invasive insertion procedures. Such catheters can be used for visualization of catheters in medical devices, systems, and methods, where they are combined with ultrasound technology to provide visualization of subcutaneous anatomical structures and the position of the device in in-plane and out-of-plane orientations, enabling projection or prediction of the position of the insertion device relative to the patient's anatomical structure, thereby improving the likelihood of successfully accessing the vascular system.

Background Art

[0002] Conventionally, during catheter insertion, the passage of needles and catheter tubing through skin tissue to reach veins is not visible to clinicians. For this reason, they must rely on their direct experience and tactile sense of needle insertion to successfully identify the location of the vein. This can be a difficult task when attempting to access small veins located deep beneath the skin, increasing the risk of excessive pain and / or injury to the patient.

[0003] Treatment guidance systems for improving visualization of invasive procedures utilize invasive devices having a magnetic field source. This can be achieved by embedding magnets at known positions on the device or by magnetizing a portion of the invasive device prior to insertion using an externally applied magnetic field. The portion of the invasive device targeted for magnetization is typically the metal cannula used during insertion of the invasive device.

[0004] In the case of vascular access devices, magnetizing metal cannulas has considerable limitations because this method does not provide precise spatial information regarding the catheter tip relative to the anatomical structure of the blood vessel. Therefore, it is difficult to ensure that the catheter is properly positioned inside the vein before cannula removal. Furthermore, once the cannula is removed, it becomes impossible to determine the location of the catheter tubing using a guidance system during the device's incarnation period. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] U.S. Patent Application Publication No. 20140257080 [Patent Document 2] International Publication No. 2013034175 [Overview of the project] [Problems that the invention aims to solve]

[0006] It is desirable to provide catheters that can be used in conjunction with devices, systems, and methods to provide improved visualization of catheters and medical devices. [Means for solving the problem]

[0007] One aspect of the present disclosure relates to a catheter comprising a polymer material, wherein at least a portion of the polymer tubing comprises a magnetized composition magnetized by an externally applied magnetic field, the magnetized composition comprising a magnetic material dispersed within the polymer. In a particular embodiment, the magnetic composition is dispersed within the polymer material forming the tubing. In a particular embodiment, the magnetized composition comprises an inner layer surrounding the catheter lumen and an outer layer of non-magnetizable polymer material, such as the polymer. In an alternative particular embodiment, the layer of magnetized composition is an outer layer surrounding the inner layer of non-magnetizable polymer. In one or more embodiments, the magnetized composition forms longitudinal segments of the catheter separated by longitudinal segments of non-magnetizable polymer material.

[0008] In any of the aforementioned embodiments of the catheter, the magnetizing composition may further include an impermeable component. Alternatively, in any of the aforementioned embodiments, the non-magnetized portion of the catheter may include an impermeable component.

[0009] Another embodiment relates to a vascular access device comprising a polymer catheter according to any of the embodiments described above. In a specific embodiment, the vascular access device is a peripheral venous catheter insertion device, or a syringe comprising a polymer catheter having a magnetized portion and a needle cannula disposed within the polymer catheter, wherein the magnetized portion of the polymer catheter has a magnetic field detectable by a magnetometer.

[0010] Another embodiment relates to a method for locating a catheter inserted into a patient's vascular system, such as a polymer catheter, the method comprising: a) magnetizing a catheter according to any of the above embodiments to provide a magnetized catheter having a known magnetic field at a selected distance through tissue of known permeability; b) measuring the intensity and direction of the magnetic field generated by the inserted catheter using a magnetometer outside the patient's body; and c) determining the location of the catheter based on the measured intensity and direction, as well as a correlation between the known magnetic field and tissue permeability at the selected distance. In one or more embodiments, the method further comprises the step of detecting the placement of a needle or cannula contained within the catheter using an ultrasound imaging system before locating the polymer catheter.

[0011] Another aspect of the use involves the use of a magnetized catheter, such as a polymer catheter, for locating a catheter within a patient's vascular system, the catheter may be as described in any of the aforementioned embodiments of a catheter, and the intensity and direction of the magnetic field generated by the catheter within the patient's vascular system are measured using a magnetometer outside the patient's body. In one or more embodiments, the use further includes detecting the placement of a needle or cannula contained within the catheter using an ultrasound imaging system before locating the polymer catheter. [Brief explanation of the drawing]

[0012] [Figure 1A] This is a perspective view of a catheter according to one embodiment. [Figure 1B] Figure 1A is an end view of the catheter. [Figure 2A] This is a perspective view of a catheter according to one embodiment. [Figure 2B] Figure 2A is an end view of the catheter. [Figure 3A] This is a perspective view of a catheter according to one embodiment. [Figure 3B]It is an end view of the catheter of FIG. 3A. [Figure 4A] It is a perspective view of a catheter according to an embodiment. [Figure 4B] It is an end view of the catheter of FIG. 4A. [Figure 5A] It is a perspective view of a catheter according to an embodiment. [Figure 5B] It is an end view of the catheter of FIG. 5A. [Figure 6] It is a perspective view of a vascular access device according to an embodiment. [Figure 7] It is a schematic diagram of an ultrasonic system according to an embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0013] Before describing some exemplary embodiments of the present disclosure, it should be understood that the present disclosure is not limited to the details of the structures or process steps described in the following description. The present disclosure is capable of other embodiments and of being practiced or carried out in various ways.

[0014] Embodiments of the present disclosure provide a catheter that can be used in various methods and systems with a variety of vascular access devices. In one or more embodiments, the catheter comprises a material containing a magnetizable component, such as polyurethane. In one or more embodiments, the catheter and the vascular access device can be utilized with an ultrasonic imaging system so that the catheter can be tracked and visualized in real time. In one or more embodiments, inserting a metal cannula into a catheter containing a magnetizable component enables ultrasound-guided needle placement, thereby enabling visualization of the insertion process and localization of the positions of both the cannula and the vein, improving the success rate of needle insertion in the first attempt. The location of the magnetized catheter or device can be determined by using a magnetometer to identify the strength and direction of the magnetic field. According to one or more embodiments, the catheter tubing can still be seen by the imaging system after the cannula is removed, thereby enabling further adjustment of the tubing within the vein if required.

[0015] One aspect is a catheter comprising polymeric tubing, at least a portion of the polymeric tubing comprising a magnetized composition magnetized by an externally applied magnetic field prior to insertion of the catheter tubing into a patient, the magnetized composition comprising a magnetic material dispersed within the polymer, relating to the catheter. One such embodiment is shown in FIGS. 1A and 1B. Referring to FIGS. 1A and 1B, a catheter 10 that can include polymeric tubing is shown, at least a portion of the catheter 10 comprising a magnetized composition 13 that includes a magnetic material dispersed within a catheter material, which may be a polymer. The magnetized composition 13 has been magnetized by an externally applied magnetic field prior to insertion of the catheter into the patient. In the illustrated embodiment, the catheter 10 is defined by an elongate tubing having an outer surface 19 surrounding the magnetized composition 13 dispersed within the polymer and an inner surface 21 defining a lumen 15.

[0016] In the specific embodiments shown in Figures 2A and 2B, the magnetized composition 113 is provided within a magnetized inner layer 114 surrounding the lumen 115 of the catheter 110, and this magnetized inner layer 114 may include polymer tubing with a non-magnetizable outer layer 117 which may include a non-magnetizable polymer. In this embodiment, the lumen 115 of the catheter 110 defined by the polymer tubing results in a magnetized inner layer 114 containing a magnetizable composition 113 dispersed within the polymer, and the non-magnetizable outer layer 117 of the catheter 110 is non-magnetizable. Thus, the catheter 110 includes a non-magnetizable outer surface 119 and a magnetized inner surface 121.

[0017] In another specific embodiment shown in Figures 3A and 3B, the magnetizing composition 213 is located within a magnetized outer layer 217 surrounding a non-magnetizable inner layer 214 of a catheter 210 which may include polymer tubing. In this embodiment, the lumen 215 of the catheter 210 is surrounded by a non-magnetizable inner layer 214 containing a non-magnetizable polymer, and the magnetized outer layer 217 contains the magnetizing composition 213 dispersed within the polymer. Thus, the catheter 210 has a magnetized outer surface 219 and a non-magnetizable inner surface 221.

[0018] In one or more alternative embodiments, the magnetized composition forms longitudinal segments or “stripe” on or within a catheter, separated by longitudinally non-magnetizable segments which may consist of a polymer. In the specific embodiments shown in Figures 4A and 4B, the magnetized longitudinal segment 313 containing the magnetized composition is surrounded by non-magnetizable segments 317 having an inner surface 321 and an outer surface 319 of a catheter 310 comprising polymer tubing. In one or more embodiments, each magnetized longitudinal segment 313 containing the magnetized composition is surrounded by non-magnetizable segments 317 within the walls of the catheter 310. In alternative embodiments, the magnetized longitudinal segment 317 may include elongated magnetized elements, such as elongated magnetized wires 314 which can be co-formed (e.g., co-extruded) with the catheter tubing, and the magnetized wires 314 may be magnetized by an external magnetic field applied before the catheter is inserted into the patient. In the embodiment shown in Figure 4B, a plurality of magnetized wires 314 are shown within each longitudinal segment 313. Other configurations are also possible, namely configurations in which fewer wires are included within each longitudinal segment 313, or configurations in which a single magnetized wire 314 is provided within each longitudinal segment. Thus, the lumen 315 of the catheter 310 is surrounded by a non-magnetized polymer, resulting in a non-magnetizable inner surface 321 and a non-magnetizable outer surface 319. As a result of magnetizing this catheter, longitudinal magnetized "stripes" or longitudinal magnetized segments are obtained within the wall of the catheter 310.

[0019] In yet another specific embodiment shown in Figures 5A and 5B, the catheter 410 includes a magnetized longitudinal segment 413 containing a magnetized composition, extending from the inner surface to the outer surface 419 of the catheter 410, which may consist of polymer tubing defining the lumen 415. Such a structure gives the catheter 410 a corresponding magnetized inner surface 423 and a magnetized outer surface 427. The magnetized longitudinal segment 427 is separated by a non-magnetizable longitudinal segment 417 which may contain a polymer, and this longitudinal segment gives the catheter 410 a corresponding non-magnetizable inner surface 425 and a non-magnetizable outer surface 429 separating the magnetized longitudinal segment 427.

[0020] In any of the aforementioned embodiments of the catheter described with respect to Figures 1A-B to 5A-B, the magnetized composition or magnetized portion of the catheter may further include an impermeable component or impermeable material. According to the various embodiments described herein, the impermeable component or impermeable material may be uniformly dispersed in the material constituting the tubing, which includes a polymer, in one or more embodiments. As an example, the magnetized portion of the catheter may include an impermeable component. The impermeable component does not transmit radiation and can be seen under X-ray photography and / or fluoroscopy (X-ray fluoroscopy). In one or more embodiments, the impermeable component is selected from, for example, barium sulfate, bismuth subcarbonate, bismuth oxychloride, bismuth trioxide, tungsten, and mixtures thereof.

[0021] Alternatively, in any of the aforementioned embodiments of the catheter, the non-magnetizable portion of the polymer tubing may contain an impermeable component. According to various embodiments described herein, the impermeable component may be dispersed within an inner non-magnetizable layer of the material forming the catheter. Alternatively, the impermeable component may be dispersed within an outer non-magnetizable layer of the material forming the catheter. In other embodiments, the impermeable component may be dispersed within a longitudinal non-magnetizable segment of the material forming the catheter. In embodiments in which the non-magnetizable portion of the polymer tubing contains an impermeable component, the impermeable component may be selected from, for example, barium sulfate, bismuth subcarbonate, bismuth oxychloride, bismuth trioxide, tungsten, and mixtures thereof.

[0022] In any of the embodiments described above, the magnetic component or magnetic material is added to a polymer material forming a catheter (e.g., silicone rubber, nitinol, nylon, polyurethane, fluoroethylene polymer (FEP), polytetrafluoroethylene polymer (PTFE), polyethylene terephthalate (PET), latex, and thermoplastic elastomer) to yield a composition which is magnetized when the magnetic component or magnetic material is added to the polymer material and a magnetic field is applied to magnetize the composition. In any of the embodiments described above, the magnetic material in the magnetized composition may be selected from powdered iron, iron oxide magnets, titanium oxide magnets, powdered iron magnets, iron alloy magnets, paramagnetic or ferromagnetic compounds containing chromium, magnesium, or molybdenum, and mixtures thereof. In a specific embodiment, the iron alloy magnet is an alloy containing nickel, zinc, and / or copper. In another specific embodiment, the magnetic material is selected from ferrites and rare earths such as neodymium-iron-boron and samarium-cobalt. Anisotropic ferrite powders offer an excellent cost-performance ratio and low electrical resistance. Rare earth elements offer higher magnetic performance, service temperature, electrical resistance, and cost.

[0023] In any of the embodiments described above, the magnetic material in the magnetization composition may be in the range of 1% to 15% (w / w) of the material forming the catheter. In a specific embodiment, the magnetic material in the magnetization composition is in the range of 1% to 10% (w / w) of the material forming the catheter. In another specific embodiment, the magnetic material in the magnetization composition is in the range of 0.5% to 5% (w / w) of the material forming the catheter. The magnetic component or magnetic material imparts a low level of magnetizability without significantly altering the original physical properties of the virgin resin or molded portion. The size and thickness of the polymer or elastomer portion, the density of the virgin material, and the type of virgin material can also affect the amount of additive required to obtain the desired detectable signal.

[0024] Magnetic components or materials may be compounded with polymers or elastomers during manufacturing to slightly magnetize the polymers or elastomers, making them more easily magnetized and detectable by metal detectors or X-ray systems. Such magnetic components or materials may be paramagnetic or ferromagnetic. Magnetic polymers may be further magnetized or polarized as a secondary process during molding. Non-limiting examples of magnetic components or materials are provided above. In the case of medical devices that come into contact with the body, the toxicity of additives is also a consideration, and therefore paramagnetic or ferromagnetic elements or compounds containing essential metals such as chromium, magnesium, and molybdenum may be used. For example, chromium, essential metals, and fairly ferromagnetic ones can be compounded with polymers in powder form and extruded to form catheter tubes.

[0025] Another aspect relates to a vascular access device comprising a catheter according to any of the embodiments described above. The vascular access device comprises a catheter sized and configured to be placed in a peripheral vein for administering a drug or fluid to a patient. After insertion, the catheter can also be used to draw blood. Such a vascular access device typically includes a metal needle (cannula) within a polymer catheter to facilitate the placement of the catheter into the vascular system. The cannula is then withdrawn, leaving the catheter in place. This disclosure provides additional options or alternatives for magnetizing the metal cannula of a vascular access device. According to one or more embodiments, the magnetized catheter remains in the patient's vascular system for long-term location detection, while the ability to detect the cannula's location is lost when the metal cannula is removed after the catheter has been placed. According to one or more embodiments, the vascular access device may be a central venous catheter, a peripherally inserted central catheter, a peripheral venous cannula, an arterial catheter, or a mid-line catheter.

[0026] Figure 6 shows an exemplary embodiment of a vascular access device 500 including a catheter according to any of the embodiments described above with respect to Figures 1A-B to 5A-B. The vascular access device 500 shown in Figure 6 comprises a catheter adapter 518 and a polymer catheter 510 including a magnetized feature 512, which includes a magnetized composition comprising a magnetized material as described herein. The magnetized portion 512 is magnetized by applying an externally applied magnetic field. By magnetizing the magnetized portion 512 of the polymer catheter 510 with an externally applied magnetic field, a magnetic field 514 is created within the region of the magnetized portion 512. The magnetic field 514 remains detectable even after the needle cannula 511 is removed from the polymer catheter 510 after it has been placed in the patient.

[0027] The vascular access device 500 may include a lateral access port 556 which may be connected to a section of an extension tube 560 to establish fluid communication between an IV fluid source and a polymer catheter 510. In one or more embodiments, the extension tube 560 is integrated to reduce contamination and mechanical phlebitis by eliminating manipulation at the insertion site. In one or more embodiments, the extension tube 560 is adapted for high-pressure injection. In one or more embodiments, the extension tube 560 provides continuous confirmation of vascular access while advancing the catheter into the patient's vein.

[0028] In one or more embodiments, the needle of the needle hub assembly 550 is inserted into the lumen (not shown) of the polymer catheter 510. The needle hub assembly 550 is shown to include a finger grip 584 positioned on the side of the needle hub assembly 550 to facilitate various insertion techniques. In one or more embodiments, a raised portion may be present on the finger grip to indicate where the user can grasp the device for needle removal. In one or more embodiments, a thumb pad 585 with a gentle convex surface is provided at the proximal end of the needle hub assembly 550. A flange 586 with a gentle convex surface is provided at the proximal end of the hub assembly to provide the finger pad. The wing member 570, the thumb pad 585, and the flange 586 are available to the user during insertion, allowing the user to choose the insertion technique to be used.

[0029] In one or more embodiments, the needle hub assembly 550 includes a needle shield 580. The needle shield 580 may be designed to secure the tip of the needle within the shield after use. In one or more embodiments, the needle shield 580 may be passively actuated. The needle tip is completely covered by the needle shield 580 in a fixed position. In one or more embodiments, a ferrule, crimp, or other structure may be included near the tip to engage with the needle shield in a particular application.

[0030] A push tab 581 may be provided to facilitate the advancement of the catheter during insertion. The push tab 581 also allows for advancement with one or both hands. In one or more embodiments, the push tab 581 is removed together with the needle shield 580. A clamp 582 may also be included on the extension tubing to prevent blood from flowing when the access port is replaced.

[0031] In one or more embodiments, the vascular access device 500 further includes a first Luer access portion 572 and a second Luer access portion 573 that are in fluid communication with an extension tube 560, a blood control split septum 574 associated with the first Luer access portion 572, and an air vent 576 associated with the second Luer access portion 573. The split septum 574 functions as a blood control septum, enabling a reduction in catheter-associated bloodstream infections (CRBSI) while providing unrestricted flow and a straight channel. In one or more embodiments, the split septum 574 may be located within the internal cavity of the catheter adapter or on the distal end of the catheter adapter. In yet another embodiment, the split septum 574 may be located on the distal end of the extension tube 560. The air vent 576 allows air to escape from the system during insertion, providing continuous confirmation of vascular access while preventing blood leakage from the system during insertion. In one or more embodiments, the air vent 576 may be located at the distal end of the extension tube 560.

[0032] The magnetic material may be compounded with the polymer in powder form during manufacturing to slightly magnetize the polymer and make it easier to magnetize. The magnetic material may be paramagnetic or ferromagnetic. Alternatively, the magnetic material may constitute elongated magnetizable elements, such as magnetizable wires that can be co-formed with tubing during processes such as extrusion molding. The magnetic material of the magnetized polymer may be further magnetized or polarized as a secondary process during molding. During the manufacture of the polymer tubing, wetting agents and emulsifiers or combinations thereof may be used to form a stable dispersion of ferromagnetic particles.

[0033] Useful polymer resins according to embodiments of this disclosure can be manufactured into tubing by conventional thermoplastic fabrication techniques, including solution casting and extrusion molding. The resin may incorporate conventional stabilizers and other additives as desired. The amounts of these materials vary depending on the application of the polymer, but they are typically present in amounts ranging from about 0.2 to 50 weight percent of the polymer.

[0034] Another aspect of the present disclosure is a method for locating a catheter inserted into a patient's vascular system, comprising the steps of: a) magnetizing a polymer catheter according to any of the above embodiments to provide a magnetized polymer catheter having a known magnetic field at a selected distance through tissue of known permeability; b) measuring the intensity and direction of the magnetic field generated by the inserted polymer catheter using a magnetometer outside the patient's body; and c) determining the location of the polymer catheter based on the measured intensity and direction, as well as a correlation between the known magnetic field and tissue permeability at the selected distance. In one or more embodiments, the method further comprises the step of detecting the arrangement of a needle contained within the polymer catheter using an ultrasound imaging system before locating the polymer catheter.

[0035] The location of a magnetized catheter / vascular access device can be achieved by determining the strength and direction of the magnetic field using a magnetometer. If an invasive catheter or vascular access device is magnetized and produces a known magnetic field B at a given distance x through tissue with permeability μr, then two such fields are given: i.e., x = f(B, μ r A mathematical correlation between them can be derived. According to one embodiment, three different magnetometers are used arranged orthogonally to each other in a three-dimensional grid array, and a three-dimensional (3D) correlation can be derived, in which case I = f(B i ,μ r) is such that i = x, y, or z along the three axes in the equation. Such a correlation can be extended to a three-dimensional (3D) magnetometer array to obtain the precise distance from the 3D magnetometer array to the magnetizing catheter or vascular access device. If the location of the 3D magnetometer array is known by reference to an ultrasonic sensor, the precise location of the magnetizing device relative to the ultrasonic sensor can be calculated. An infrared image of the device can then be produced, superimposed on the ultrasonic image, and displayed. An exemplary magnetic sensing method for determining the location of a magnetizing invasive device from the magnetic field strength measured using a magnetometer outside the body, using a magnetometer and a lookup table instead of a mathematical function, is shown and described in Patent Document 1. The method described in Patent Document 1 can be adapted to be described herein, for example, the three-dimensional (3D) correlation is from a mathematical function, and this correlation can be extended to a three-dimensional (3D) magnetometer array, one of which is outside the patient's body, to obtain the precise distance from the 3D magnetometer array to the magnetizing catheter or vascular access device. Another exemplary method of referencing a magnetometer to an ultrasonic probe is described in Patent Document 2 of the PCT Patent Application Publication, which can be adapted as described herein. For example, as shown in Figure 7, an ultrasonic system 700 is shown including a polymer catheter 510, which includes a magnetized portion 512 including a magnetized composition containing a magnetizing material as described herein, shown inside the patient's body 600. A magnetic field 514 from the polymer catheter 510 can be detected together with the Earth's magnetic field and any other background magnetic field using a magnetic field detector 712 including an array of magnetometers 720 (not shown, which can be housed in the probe of the ultrasonic system). The magnetic field detector 712 communicates with an ultrasonic processor 730 adapted to determine the position and orientation of the polymer catheter 510 relative to the magnetic field detector 712 from the detected field. This magnetically detected position is then displayed on a display 750 together with an ultrasonic image.

[0036] The ultrasound system 700 can be a standard two-dimensional B-mode ultrasound system with a standard ultrasound probe, modified by the addition of a magnetometer 712. An ultrasound processor 730, which can be connected to the ultrasound probe via a cable 735, sends an electrical signal to the magnetometer 712 to generate an ultrasound pulse, interprets the raw echo data received from the transducer probe housing the magnetometer 712, and incorporates it into an image of the patient's tissue.

[0037] The magnetometer 712 can be attached to an ultrasonic probe and is battery-powered or can be powered by the ultrasonic system. In a specific embodiment, a positioning element is provided on the magnetometer 712 to ensure that it is always mounted in the same precisely defined position and orientation. The magnetometer 712 can be connected to a base unit 740 by wireless connection, and the base unit 740 communicates wirelessly or wired (e.g., USB) with the ultrasonic processor 730 and the display 750. The base unit 740 can be integrated with the ultrasonic processor 730 or the magnetometer 712, or they can perform some of its functions.

[0038] The base unit 740 receives normalized measurements from the magnetic field detector 712 and calculates the position of the polymer catheter 510, or optionally, its position and orientation. The base unit 740 can also receive additional information, such as the charge status of the magnetic field detector's battery, and can transmit information such as configuration information from the base unit 740 to the magnetic field detector 712. The base unit 740 transfers the calculation results, namely the position and optionally the orientation, to the ultrasound processor 730 to include the polymer catheter 510 in the displayed ultrasound image.

[0039] In one or more embodiments, the base unit 740 can be incorporated into the ultrasonic system 700, in which case the ultrasonic processor 730 and the magnetometer 712 communicate directly with the ultrasonic system 700 via a wireless link or using the same physical cable 735.

[0040] Therefore, in one or more embodiments, the magnetized composition is magnetized using any suitable device for magnetizing a needle or medical device before inserting the catheter into the patient, generating a magnetic field B at a distance x through tissue with permeability μ, and its correlation is calculated as x = f(B, μr). Similar correlations can be calculated for the y-axis, z-axis, and relative angular motion ω, for example y = f(B, μr). r ), z=f(B,μ r ) and ω=f(B,μ r ) is obtained. In one or more embodiments, three magnetometers 720 are placed orthogonally to each other, and a three-dimensional correlation I = f(B i ,μ r ) is used to derive the formula, where i = x, y, or z along the three axes. In a specific embodiment, the distance from the magnetized polymer catheter to the three-dimensional array of magnetometers is calculated. In another specific embodiment, the location of the array of magnetometers referring to the ultrasonic sensors of an ultrasonic imaging system is used to calculate the location of the polymer catheter relative to the ultrasonic sensors. In yet another specific embodiment, the method includes the step of displaying an image of the polymer catheter superimposed on an ultrasonic image of the needle.

[0041] Another aspect of the present disclosure relates to the use of a magnetized polymer catheter for locating a catheter within a patient's vascular system, the catheter may be as described in any of the embodiments described above, and the intensity and direction of the magnetic field generated by the polymer catheter within the patient's vascular system are measured using a magnetometer outside the patient's body. In one or more embodiments, the use further includes detecting the arrangement of a needle contained within the polymer catheter using an ultrasound imaging system before locating the polymer catheter. In specific embodiments, the use further includes displaying an image of the polymer catheter superimposed on an ultrasound image of the needle.

[0042] The catheters described herein may be used in a variety of medical procedures, including, but are not limited to, vascular access, local anesthesia, minimally invasive surgery, biopsy, detection of bioelectrical signals, and musculoskeletal injections. Accordingly, the catheters described herein may be used in any procedure where it is desired to guide a medical device to a desired location within a patient's body and / or to monitor or track the location of the medical device to ensure that it remains in the desired location.

[0043] While the disclosures herein have been described with reference to specific embodiments, it should be understood that these embodiments merely illustrate the principles and applications of the disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the methods and apparatus of the disclosure without departing from the spirit and scope of the disclosure. Therefore, it is intended that the disclosure includes modifications and variations that fall within the scope of the accompanying claims and their equivalents.

Claims

1. A catheter comprising a polymer tube, wherein at least a portion of the polymer tube comprises a magnetized portion, the magnetized portion having a permeability μr and generating a known magnetic field B at a distance x, the position of the catheter being detectable by a magnetometer, the position of the catheter being calculated based on a correlation between the measured intensity and direction of the known magnetic field and the permeability μr of the magnetized portion at a selected distance x, in a correlation calculated as x = f(B, μr), and the magnetized portion comprising a magnetized composition comprising a magnetic material dispersed in a polymer, A catheter in which the magnetized portion forms a plurality of magnetized longitudinal segments extending from the inner surface to the outer surface of the polymer tube, and the plurality of magnetized longitudinal segments are separated along the circumferential direction of the catheter by a plurality of longitudinally non-magnetizable segments present between the plurality of magnetized longitudinal segments in the circumferential direction of the catheter.

2. The catheter according to claim 1, further comprising a radiopaque component in the magnetized portion.

3. The catheter according to claim 2, wherein the radiopaque component is selected from the group consisting of barium sulfate, bismuth carbonate, bismuth oxychloride, bismuth trioxide, tungsten, and mixtures thereof.

4. The catheter according to claim 1, further comprising a radiopaque component selected from the group consisting of barium sulfate, bismuth subcarbonate, bismuth oxychloride, bismuth trioxide, tungsten, and mixtures thereof, in the magnetization composition.

5. The catheter according to claim 1, wherein the magnetized portion includes a magnetized wire co-formed with the plurality of magnetized longitudinal segments of the polymer tube.

6. The catheter according to claim 1, wherein the magnetic material is selected from the group consisting of powdered iron, iron oxide magnetic material, titanium oxide magnetic material, powdered iron magnetic material, iron alloy magnetic material, paramagnetic or ferromagnetic compounds containing one of chromium, magnesium, and molybdenum, and mixtures thereof.

7. The catheter according to claim 6, wherein the iron alloy magnetic material is an alloy of nickel, zinc, and / or copper.

8. The catheter according to claim 1, wherein the magnetic material in the magnetized composition is less than 15% (w / w) of the polymer.

9. The catheter according to claim 8, wherein the magnetic material in the magnetized composition is less than 10% (w / w) of the polymer.

10. The catheter according to claim 8, wherein the magnetic material in the magnetized composition is less than 5% (w / w) of the polymer.

11. A vascular access device comprising a polymer catheter as described in claim 1, The polymer catheter has a proximal end and a distal end, and the device is A catheter adapter comprising a distal end, a proximal end, a total length extending from the distal end to the proximal end, an internal cavity, an upper portion, a lower portion, and a tip region having a distal opening with a circumference through which the polymer catheter extends, and connected to the proximal end of the polymer catheter, A needle cannula disposed together with the polymer catheter, wherein the magnetized portion of the polymer catheter has a magnetic field detectable by a magnetometer, and A vascular access device with additional features.

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