Trackable catheter placement system and methods of manufacturing and using the same

Abstract

The present application relates to trackable catheter placement systems and methods of manufacturing and using the same. A trackable medical device, such as a catheter placement system, has a needle formed of magnetizable material and magnetized to produce a magnetic field having a magnetic field strength or magnetic field signature detectable by a sensor of a tracking system. The medical device also includes a spring formed of a non-magnetizable material, such as silver-plated copper beryllium or the like, and configured to exhibit the same mechanical performance characteristics as a spring formed of magnetizable material. A method of tracking a medical device is also disclosed, including magnetizing a catheter placement system to produce a magnetic field having a strength or magnetic field signature, and detecting the magnetic field by a sensor of a tracking system.

Description

[0001] priority

[0002] This application claims the benefit of priority to U.S. Provisional Application No. 63 / 083,624, filed September 25, 2020, which is incorporated herein by reference in its entirety. Technical Field

[0003] This application relates to the field of medical devices, and more specifically to traceable catheter placement systems and methods of manufacturing and using the same. Summary of the Invention

[0004] In brief, the embodiments disclosed herein relate to a trackable medical device with improved magnetic position or orientation recognition and improved trajectory prediction.

[0005] Magnetic tracking systems, such as those used to track medical devices, needles, catheters, etc., rely on detecting the magnetic field of a magnetizable component associated with the trackable medical device. In one embodiment, the trackable medical device may include a catheter placement system with a needle that can be magnetized to provide a magnetic field. The magnetic tracking system can be configured to detect the strength or characteristics of the magnetic field to determine the position, orientation, or trajectory of the needle in the catheter placement system.

[0006] However, additional components of a catheter placement system also made of magnetizable materials may provide additional magnetic fields. The strength or characteristics of these secondary magnetic fields may mask or interfere with the strength or characteristics of the first magnetic field, thereby inhibiting the performance of the tracking system in accurately determining the position, orientation, or trajectory of the needle. This document discloses a medical device comprising a needle made of a magnetizable material and additional components made of a non-magnetizable material to suppress the masking or interference of the first magnetic field from the needle.

[0007] However, replacing components made of magnetizable materials with the same components made of non-magnetizable materials presents additional problems. Non-magnetizable materials exhibit different mechanical properties, and therefore, the performance of these components can vary significantly, leading to reduced functionality or malfunction of the entire medical device. This document also discloses components made of non-magnetizable materials and configured to provide the same mechanical properties as components made of magnetizable materials.

[0008] This paper discloses a traceable catheter placement system comprising: a needle formed of a magnetizable material and magnetized to generate a magnetic field having one or both of a magnetic field strength and a magnetic field signature detectable by sensors of the traceable system; and a spring formed of a non-magnetizable material and configured to exhibit the same mechanical properties as a spring formed of a magnetizable material.

[0009] In some embodiments, the non-magnetizable material includes copper, beryllium, an alloy containing copper and beryllium, or a silver-coated copper-beryllium alloy. In some embodiments, the magnetizable material includes 17-7 precipitation-hardened stainless steel. In some embodiments, the spring has a core diameter of 0.0113 ± 0.001 inches. In some embodiments, the spring includes 30 to 37 active coils. In some embodiments, the spring has a solid length between 0.45 inches and 0.49 inches. In some embodiments, the spring has a coil pitch angle between 12 degrees and 16 degrees.

[0010] In some embodiments, the spring has a spring diameter of 0.205 ± 0.005 inches. In some embodiments, the spring includes three dead coils at the distal end and two dead coils at the proximal end. In some embodiments, the spring has a distal expansion diameter of 0.215 inches. In some embodiments, the tracking system includes a passive magnetic tracking system configured to detect the magnetic field strength of the needle. In some embodiments, the tracking system includes an electromagnetic tracking system configured to detect the magnetic field characteristics of the needle.

[0011] A method for tracking a catheter placement system is also disclosed, the method comprising providing a catheter placement system having a needle formed of a magnetizable material and a spring formed of a non-magnetizable material and configured to exhibit the same mechanical properties as a spring formed of a magnetizable material, magnetizing the catheter placement system so that a magnetic field with magnetic field strength or magnetic field characteristics is generated by the needle, and detecting the magnetic field by a sensor of the tracking system.

[0012] In some embodiments, the non-magnetizable material includes copper, beryllium, an alloy containing copper and beryllium, or a silver-plated copper-beryllium alloy. In some embodiments, the magnetizable material includes ferrous materials, steel, stainless steel, 304 stainless steel, or 17-7 precipitation-hardening stainless steel. In some embodiments, the spring has a core diameter of 0.0113 ± 0.001 inches. In some embodiments, the spring comprises 30 to 37 effective coils. In some embodiments, the spring has a body length between 0.45 inches and 0.49 inches. In some embodiments, the spring has a coil pitch angle between 12 degrees and 16 degrees.

[0013] In some embodiments, the spring has a spring diameter of 0.205 ± 0.005 inches. In some embodiments, the spring includes three deactivated coils at the distal end and two deactivated coils at the proximal end. In some embodiments, the spring has a distal expansion diameter of 0.215 inches. In some embodiments, the method further includes determining one of the needle's position, orientation, or trajectory. In some embodiments, the tracking system includes a passive magnetic tracking system configured to detect the magnetic field strength of the needle. In some embodiments, the tracking system includes an electromagnetic tracking system configured to detect the magnetic field characteristics of the needle.

[0014] A method for manufacturing a traceable medical device is also disclosed, comprising providing a medical device including a needle extending from the distal end of a body and a spring disposed within the body, the needle being configured to enter a patient's vascular system and being formed of one of 304-stainless steel or 17-7 precipitation-hardening stainless steel, the spring comprising copper and beryllium, placing a portion of the medical device in a magnetizer including magnetic elements to magnetize the needle and spring and provide a first magnetic signal from the needle. Attached Figure Description

[0015] A more specific description of the disclosed text will be presented by reference to specific embodiments of the disclosed text shown in the accompanying drawings. It should be understood that these drawings depict only typical embodiments of the invention and are therefore not intended to be limiting of its scope. Exemplary embodiments of the invention will be described and explained with additional specific description and detail using the accompanying drawings, wherein:

[0016] Figure 1A A perspective view of an exemplary medical device according to an embodiment disclosed herein is shown.

[0017] Figure 1B An exploded view of an exemplary medical device according to an embodiment disclosed herein is shown.

[0018] Figure 2A An exemplary tracking system for tracking a medical device including a magnetizable component, according to an embodiment disclosed herein, is shown.

[0019] Figure 2B An exemplary tracking system for tracking a medical device including non-magnetizable components is shown according to an embodiment disclosed herein.

[0020] Figure 3 Construction details of an exemplary spring according to an embodiment disclosed herein are shown.

[0021] Figure 4A Magnetizable embodiments according to the present invention are shown. Figure 1A A perspective view of an exemplary magnetizer for a medical device.

[0022] Figure 4B The embodiments disclosed herein are shown. Figure 4A An exploded view of the magnetizer device.

[0023] Figure 5A A perspective view of a sensor for a tracking system including the x-axis and z-axis according to an embodiment disclosed herein is shown.

[0024] Figure 5B A side view of a sensor for a tracking system including z-axis and y-axis according to an embodiment disclosed herein is shown.

[0025] Figures 6A-6D A bar graph showing the results from testing an exemplary medical device according to an embodiment disclosed herein. Detailed Implementation

[0026] Before disclosing some specific embodiments in more detail, it should be understood that the specific embodiments disclosed herein do not limit the scope of the concepts provided herein. It should also be understood that the specific embodiments disclosed herein may have features that can be readily separated from the specific embodiments and optionally combined with or substituted for any of the other several embodiments disclosed herein.

[0027] Regarding the terminology used herein, it should be understood that these terms are for the purpose of describing certain specific embodiments and do not limit the scope of the concepts presented herein. Ordinal numbers (e.g., first, second, third, etc.) are generally used to distinguish or identify different features or steps within a set of features or steps and do not provide for a sequence or numerical limitation. For example, features or steps “first,” “second,” and “third” do not necessarily appear in that order, and a particular embodiment including such features or steps is not necessarily limited to these three features or steps. Labels such as “left,” “right,” “top,” “bottom,” “front,” and “back” are used for convenience and do not imply, for example, any particular fixed position, orientation, or direction. Rather, such labels are used to reflect, for example, relative position, orientation, or direction. Unless the context clearly specifies otherwise, the singular forms of “a,” “an,” and “the” include plural references.

[0028] Regarding "proximal," for example, the "proximal portion" or "proximal portion" of a needle disclosed herein includes a portion of the needle intended to be close to the clinician when the needle is used on a patient. Similarly, the "proximal length" of a needle includes, for example, the length of the needle intended to be close to the clinician when the needle is used on a patient. For example, the "proximal end" of a needle includes one end of the needle intended to be close to the clinician when the needle is used on a patient. The proximal portion, proximal portion, or proximal length of a needle may include the proximal end of the needle; however, the proximal portion, proximal portion, or proximal length of a needle does not need to include the proximal end of the needle. That is, unless the context otherwise requires, the proximal portion, proximal portion, or proximal length of a needle is not the distal portion or distal length of the needle.

[0029] Regarding "distal," for example, the "distal portion" or "distal part" of a needle disclosed herein includes a portion of the needle intended to be close to or within the patient when the needle is used on the patient. Similarly, for example, the "distal length" of a needle includes the length of the needle intended to be close to or within the patient when the needle is used on the patient. For example, the "distal end" of a needle includes one end of the needle intended to be close to or within the patient when the needle is used on the patient. The distal portion, distal part, or distal length of a needle may include the distal end of the needle; however, the distal portion, distal part, or distal length of a needle does not need to include the distal end of the needle. That is, unless the context otherwise requires, the distal portion, distal part, or distal length of a needle is not the distal portion or distal length of the needle.

[0030] To help describe the implementation scheme described in this article, and as Figure 1A As shown, the longitudinal axis extends substantially parallel to the axial length of needle 102. The lateral axis extends perpendicular to the longitudinal axis, while the transverse axis extends perpendicular to both the longitudinal and lateral axes.

[0031] As used herein, "magnetic intensity" is defined as the absolute measurement of magnetic field strength. As used herein, "magnetic characteristic" is defined as the difference between one or more parameters defining an electromagnetic field, such as wavelength, frequency, amplitude, and combinations thereof.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.

[0033] Figure 1A-1B Details of an exemplary medical device 100 are shown, which typically includes an elongated cannula or needle 102 extending along a longitudinal axis and supported at its proximal end by a bushing, housing, or elongated body 104. In one embodiment, the medical device 100 may include a catheter placement system, needle, cannula, trocar, guidewire, or similar elongated medical device comprising a portion configured for subcutaneous insertion into a patient. In one embodiment, the catheter placement system may be ACCUCATH. TMCatheter placement systems, etc. As used herein, the exemplary medical device 100 may also be referred to as catheter placement system 100; however, this is not intended to be limiting. Similarly, the body 104 is not intended to be limiting and may also include various handles, housings, connectors, extension legs, or similar support or connection structures. It should be understood that, as used herein, the term "medical device" is exemplary and not intended to be limiting, and the embodiments described herein can be used for any device capable of being tracked by a magnetic tracking system. For example, trackable devices used in the construction industry, measurement, etc.

[0034] In one embodiment, needle 102 may define a lumen 106 extending along a longitudinal axis and providing fluid communication between a distal tip 108 of needle 102 and a proximal end 110 of needle 102. In one embodiment, needle 102 or cannula may define a sharp distal tip 108. In one embodiment, medical device 100 may include a catheter 120, sheath, or similar tubular device disposed on the outer surface of needle 102. Catheter 120 may be supported by a catheter bushing 122. Catheter 120 may be selectively detached from needle 102. In one embodiment, medical device 100 may include a second elongated medical device, such as a guidewire 112 extending through the lumen 106 of needle. In one embodiment, the second elongated medical device may be formed of a non-magnetic material, as described herein.

[0035] In one embodiment, the needle 102 may be slidably engaged with the body 104 along a longitudinal axis. In one embodiment, the medical device 100 may include a needle retraction system 130. The needle retraction system 130 may be configured to retract the needle 102 close to the body into the body 104 after successful placement of the catheter 120. Advantageously, the needle 102 can be retracted into the body 104 to mitigate accidental needlestick injuries and / or reduce contamination by fluids (such as blood) present thereon.

[0036] The needle retraction system 130 may include an actuator 132 and a biasing member 134, such as a compression spring, disposed within a portion of the body 104. The biasing member 134 may be coupled to the needle 102 and may bias the needle 102 toward a retracted position disposed within the body 104. The actuator 132 may be configured to hold the needle 102 in an extended position, in which a portion of the needle 102 is disposed distally at the distal end of the housing 104, for example, as shown in FIG1. ​​Actuating the actuator 132 may allow the biasing member 134 to push the needle toward the retracted position within the body 104. Further details of catheter placement systems including needle retraction systems can be found in U.S. Patent Nos. 5,865,806; 5,911,705; 8,728,035; 9,162,037; and 10,220,191, each of which is incorporated herein by reference in its entirety.

[0037] In one embodiment, the medical device 100 may include a blood scintillation indicator 136 in fluid communication with the needle. The blood scintillation indicator 136 may be configured to indicate when the distal tip 108 of the needle has entered the patient's vascular system. In one embodiment, the medical device 100 may include a guidewire advancement assembly 140 slidably engaged with the body 104 and configured to selectively advance a guidewire 112 through the lumen 106 of the needle and into the patient's vascular system. In one embodiment, the medical device 100 may include a cap 114 disposed on the needle 102, extending distally from the body 104 and selectively removable from the body and configured to protect the needle 102 during storage or transport.

[0038] In one embodiment, a portion of the medical device 100 may be magnetized, such as needle 102, and used with various tracking systems employing one or more tracking modalities. Exemplary modalities may include ultrasound, passive (“permanent”) magnetic tracking, electromagnetic tracking, and combinations thereof.

[0039] Figure 2A-2BDetails of an exemplary tracking system 220 are shown. The tracking system 220 typically includes a probe 222 communicatively coupled to a console 226. The probe 222 may include an ultrasound transducer and one or more sensors 224. The ultrasound transducer may be configured to emit and receive acoustic signals to provide an image of a subcutaneous target location (e.g., a target blood vessel). The one or more sensors 224 may be configured to detect one or more modalities, such as magnetic fields, electromagnetic fields, etc. In one embodiment, the tracking system 220 may utilize an ultrasound modality to image a subcutaneous target area and also use a magnetic modality to track the position of the medical device 100 relative to the probe 222. The tracking system 220 may also include a console 226 with a display configured to display both the imaged subcutaneous target area and the position of the medical device 100 relative to the target area.

[0040] In one embodiment, medical device 100 or a portion thereof may include a magnetizable material, such as a metal, alloy, composite material, steel, stainless steel, 304 stainless steel, 17-7 precipitation-hardening stainless steel (“17-7PH SS”), or similar magnetizable materials. In one embodiment, the needle 102 of medical device 100 may be formed of a magnetizable material and may be magnetized to provide a passive (“permanent”) magnetic field. In one embodiment, medical device 100 may include one or more components configured to generate an electromagnetic field from needle 102. Thus, the magnetized medical device 100 generates a magnetic field that can be detected by probe 222 of tracking system 220. Tracking system 200 may detect and analyze the strength and / or characteristics of the magnetic field and determine the position, orientation, or trajectory of medical device 100 relative to tracking system 220.

[0041] Further details of this multimodal tracking system can be found, for example, in U.S. Patent Nos. 8,388,541; 8,478,382; 8,781,555; 8,849,382; 9,456,766; 9,492,097; 9,521,961; 9,526,440; 9,554,716; 9,636,031; 10,449,330; and U.S. Publication No. 2018 / 011655, each of which is incorporated herein by reference in its entirety.

[0042] Continue to refer to Figure 2AThe exemplary medical device may include one or more components, such as spring 134, separate from the magnetized needle 102 and also formed of a magnetizable material (e.g., steel). One or more components may include springs, clips, needle safety clips, guidewire advance assemblies, blood flashing indicators, and similar structures that partially or rely on steel or similar ferrous materials to provide preferred mechanical properties and the desired mechanical function. While these components may not be intentionally magnetized, they may still provide a second magnetic signal 242 with a different intensity and / or magnetic characteristics than the first magnetic signal 240 of the needle 102.

[0043] The second magnetic signal 242 of the component may mask or interfere with the first magnetic signal 240 of the needle 102, making the first magnetic signal 240 more difficult to distinguish and reducing the accuracy of the tracking system 220 in predicting the position, orientation or trajectory of the needle 102.

[0044] In one implementation, the second magnetic signal 242 may mask the intensity of the first magnetic signal 240 by providing a second magnetic signal 242 with a second magnetic field strength. This second magnetic field strength, or "background noise," may reduce the signal-to-noise ratio of the first magnetic signal 240 relative to the background noise, thereby making the first magnetic signal 240 harder to distinguish or completely masking it.

[0045] In one embodiment, the second magnetic signal 242 of the component may interfere with the characteristics of the first magnetic signal 240. For example, when the first magnetic signal 240 is set as an electromagnetic wave with different magnetic characteristics, the second magnetic signal 242 may interfere with the first magnetic signal 240 by means of a constructive wave or a destructive wave. The masking or interference of the first magnetic signal 240 by the second magnetic signal 242 may be referred to as providing a “dirty” signal, which may reduce the accuracy of the tracking system 220 in determining the position, orientation, or trajectory of the medical device 100.

[0046] like Figure 2B As shown, in one embodiment, medical device 100 may include a component formed of a non-magnetizable material, such as a non-magnetizable spring 334. Exemplary non-magnetizable materials may include non-ferrous metals, alloys, plastics, polymers, copper, beryllium, copper-beryllium alloys, silver-plated copper-beryllium, etc. The non-magnetizable component 334 provides little or no magnetic signal, so medical device 100 provides only, for example, a "clean" first magnetic signal 240 from needle 102. This first magnetic signal 240 is not masked and / or interfered with by any secondary magnetic signals. The signal strength is discernible over reduced background noise, i.e., a large signal-to-noise ratio, and the characteristics of the signal are undisturbed. This increases the accuracy of tracking system 220 in tracking and predicting the position, orientation, or trajectory of medical device 100.

[0047] However, it is important to note that non-magnetizable metals, alloys, plastics, polymers, copper, beryllium, copper-beryllium alloys, silver-plated copper-beryllium, etc., exhibit different mechanical properties than magnetizable materials (e.g., steel, stainless steel, 304 stainless steel, 17-7PH SS, etc.). Exemplary mechanical properties may include density, minimum tensile strength, elastic modulus (tensile), torsional modulus (compressive), shear strength, ductility, and combinations thereof. Therefore, the mechanical properties of non-magnetizable components may differ significantly from those of non-magnetizable components, leading to reduced performance or malfunction of medical devices.

[0048] Figure 3 Table 1 below illustrates the construction details of a spring 330 formed from a magnetizable material, such as 304 stainless steel, and a spring 334 formed from a non-magnetizable material, such as a silver-plated copper-beryllium alloy. For example, Table 1 below shows the construction details of an exemplary magnetizable spring 330 and an exemplary non-magnetizable spring 334. The non-magnetizable spring 334 may be formed from silver-plated copper-beryllium and provides the same mechanical properties as the magnetizable spring 330 formed from 304 stainless steel. Table 1 below compares the spring design differences between the magnetizable spring 330 and the non-magnetizable spring 334.

[0049] Table 1: Exemplary differences in spring construction

[0050]

[0051]

[0052] Figure 3An exemplary spring is shown, indicating the construction measurements listed in Table 1. The core diameter parameter (inches) 302 is the diameter of the wire forming springs 330, 334. The effective coil parameter (#) 304 is the number of effective coils within springs 330, 334. As shown, these effective coils 304 are arranged between ineffective coils 312, 314, which are located at either end of springs 330, 334. However, it should be understood that springs 330, 334 may include one or more effective coils 304 located at one of their proximal or distal ends, or may include one or more ineffective coils 312, 314 located at the midpoint of springs 330, 334. The body length parameter (inches) 306 is the longitudinal length of the spring from proximal to distal end. The pitch angle parameter (degrees) 308 is the angle of coils 304, 312, 314 relative to an axis extending perpendicular to the longitudinal axis of springs 330, 334. The spring diameter parameter (inches) 310 is the outer diameter of the spring extending along an axis perpendicular to the longitudinal axis. The parameters for the inactive coil at the distal end (#) 312 and the inactive coil at the proximal end (#) 314 are the number of coils extending substantially perpendicular to the longitudinal axis and respectively located at the distal and proximal ends. The distal expansion diameter parameter (inches) 316 is the widest diameter of the spring extending along an axis perpendicular to the longitudinal axis at one or both the proximal and distal ends.

[0053] Advantageously, the difference in construction between the non-magnetizable spring 334 and the magnetizable spring 330 provides a spring with the same mechanical properties while the overall dimensions of the spring change very little or not at all. For example, a difference in one of the following: the number of effective coils, the coil pitch angle, or the diameter of the core wire, can modify the mechanical properties of the non-magnetizable spring 334 to be equal to those of the magnetizable spring 330 while keeping the diameter or length of the spring substantially the same. Advantageously, the non-magnetizable spring 334 thus constructed can be used in the existing design of the medical device 100 to provide the same mechanical properties without having to resize the medical device 100 to accommodate a completely different spring.

[0054] like Figures 4A-4B As shown, in one embodiment, an exemplary method for magnetizing a medical device 100 is provided. Figure 4AAs shown, a magnetizing device (“magnetizer”) 150 is provided, comprising one or more magnetic elements 152. The magnetic element 152 may include a permanent magnet, an electromagnet, or a combination thereof. The magnetizing device 150 may be configured to align a medical device 100 relative to the magnetic element 152 in a predetermined orientation. The magnetizing device 150 then exposes the medical device 100 or a portion thereof to the magnetic element 152 to magnetize the medical device 100. Exposure of the medical device 100 to the magnetic element 152 causes electronic alignment of the metallic portions of the medical device 100 and applies a magnetic field to the medical device 100. In one embodiment, the field lines of the magnetic field are aligned with the axis of the medical device 100. Further details of exemplary magnetizing devices can be found in U.S. Publication No. 2018 / 0310955, the entire contents of which are incorporated herein by reference.

[0055] Advantageously, the direct magnetization of the medical device 100 offers a simplified manufacturing process, reduced complexity, and improved manufacturing speed and cost. This is in contrast to medical devices that include separate, permanent magnetic materials (included in the medical device 100) to provide a magnetic field. For example, providing a needle 102 of the medical device 100 formed of a first material (e.g., 304 stainless steel) and including a permanent magnet formed of a second material (e.g., ferrite) increases the complexity of combining two contrasting materials into one device. Furthermore, the device requires the orientation of the needle 102 to be aligned with the magnetic field. Similarly, forming a medical device 100 that includes electromagnetic elements requires further manufacturing complexity and a power source.

[0056] It should be understood that when the medical device 100 is placed near the magnetizer 150, one or more components of the medical device 100 may be magnetized. Since these additional components (e.g., the magnetizable spring 134) are differently positioned and aligned relative to the magnetic element 152 of the magnetizer 150, the secondary magnetic signal 242 applied to these one or more components may interfere with the primary magnetic signal 240 of the needle 102, as described herein.

[0057] In one embodiment, a medical device 100 is provided including a non-magnetizable spring 334 formed of copper, beryllium, a copper-beryllium alloy, a silver-plated copper-beryllium alloy, or a combination thereof, and constructed as described in Table 1. Advantageously, when the medical device 100 is exposed to a magnetizer 150, the non-magnetizable spring 334 can be particularly resistant to magnetization, thereby reducing or eliminating any secondary magnetic signal 242 or "background noise" from the spring 334. Further, the spring 334 formed of copper, beryllium, or an alloy thereof and constructed as described in Table 1 can provide the same external dimensions and the same mechanical properties as a magnetizable spring 134 formed of steel, stainless steel, 304 stainless steel, etc. Therefore, the non-magnetizable spring 334 can be arranged within the medical device 100 without any further redesign or reconstruction of the medical device 100, thereby reducing inventory and associated manufacturing and logistics costs.

[0058] Table 2: Comparison of the composition of 17-7 stainless steel and 304 stainless steel

[0059] chromium 16.0-18.0 18.0-20.0 nickel 6.50-7.75 8.0-10.5 aluminum 0.75-1.50 0.00 manganese Maximum 1.00 Maximum 2.0 silicon Maximum 1.00 Maximum 0.75 carbon Maximum 0.09 Maximum 0.08 phosphorus Maximum 0.04 Maximum 0.045 sulfur Maximum 0.03 Maximum 0.03 nitrogen 0.00 Maximum 0.10 iron Supplement the remaining part Supplement the remaining part

[0060] In one embodiment, medical device 100 may include a needle 102 formed of 17-7PH SS. Table 2 above compares the chemical composition of 17-7 stainless steel and 304 stainless steel. In one embodiment, the 17-7 stainless steel, as detailed in Table 2, is further treated using a precipitation hardening process. A precipitation hardening process typically involves a solution treatment, which includes heating the 17-7 stainless steel to a relatively high temperature and treating it with a solution. This is followed by a quenching process, which involves rapidly cooling the solution-immersed metal. Then comes an aging process, which involves heating the metal to a relatively moderate temperature and then rapidly cooling it. The precipitation hardening process can be carried out in a vacuum or inert atmosphere and can include temperatures ranging from 900 to 1150 degrees Fahrenheit. However, it should be understood that higher and lower temperatures are also possible. In one embodiment, the duration of the process can range from one hour to several hours, depending on the exact material and properties required, but shorter and longer times are also expected. The precipitation hardening process of 17-7 stainless steel provides 17-7PH SS comprising particles uniformly dispersed within the metal's grain structure. This may impede particle movement, thereby providing improved mechanical strength properties.

[0061] 17-7PH SS can exhibit mechanical and corrosion resistance properties comparable to or improved compared to standard 304 stainless steel (“304SS”). Furthermore, compared to devices formed of 304 stainless steel, 17-7PH SS can exhibit improved magnetic permeability when magnetized using magnetizer 150 with the same magnetization method, thereby allowing the needle 102 of medical device 100 to generate a stronger magnetic field, as described herein.

[0062] Advantageously, devices formed from 17-7PH SS offer surprisingly improved tracking performance compared to similar devices formed from 304 stainless steel. Therefore, medical devices formed from 17-7PH SS can provide approximately twice the improved exit distance, approximately twice the improved mating distance, improved true position versus calculated position with an error distance reduced by up to half, or improved immunity to magnetic interference. Improved immunity to magnetic interference, as described in more detail herein (see Table 4), can be demonstrated by reducing the error distance from between 34% and 57% (as seen in devices formed from 304 stainless steel) to less than 3% (as seen in similar devices formed from 17-7PH SS). Furthermore, the variation in magnetic field strength between individual needles formed from 17-7PH SS is smaller when subjected to the same magnetization process. Furthermore, needles formed from 17-7PH SS are more resistant to demagnetization. In other words, the strength of the magnetic field is more reliable. Therefore, in one embodiment, the provided medical device 100 includes a needle 102 formed of 17-7PH SS and a spring 334 formed of copper, beryllium, or an alloy thereof and constructed as detailed in Table 1. Thus, the medical device 100 can be magnetized by a magnetizer 150 to apply a strong and stable magnetic signal 240 to the needle 102 and minimize any secondary magnetic signal 242 applied to the spring 334. This provides a high signal-to-noise ratio between the primary magnetic signal 240 and the secondary magnetic signal 242, thereby improving the accuracy and reliability of tracking the needle 102 using the multimodal tracking system 220, as described herein.

[0063] The present invention is further illustrated by the following exemplary experiments, which should not be construed as limiting the scope of the invention in any way. Rather, it should be clearly understood that, after reading this description, those skilled in the art can employ various other embodiments, modifications, and equivalents thereto without departing from the spirit of the invention and / or the scope of the appended claims.

[0064] Experiment 1

[0065] This exemplary experiment demonstrates that, compared to an exemplary needle formed of 304 stainless steel, an exemplary needle formed of 17-7PH SS exhibits superior magnetic tracking performance when magnetized by proximity to a magnetic source, as described herein.

[0066] scope

[0067] These exemplary test results illustrate the differences in magnetic tracking performance among the three exemplary magnetized needles.

[0068] Material

[0069] The three exemplary needle types tested included: A) a 21G needle made of 304 stainless steel; B) an 18G needle made of 304 stainless steel; and C) an 18G needle made of 17-7PH SS. The specifications of the three types of needles used in the experiment are shown in Table 3 below.

[0070] Table 3: Specifications of the three types of needles used in the experiment

[0071] Fineness (G) 21G 18G 18G Material 304 stainless steel 304 stainless steel 17-7PH SS

[0072] The tracking system 220 includes a magnetic sensor 224 and a probe 222 configured to detect magnetic fields. Magnetic tracking performance is quantified based on the position of the test needle 102 in three-dimensional space relative to the sensor 224. Figures 5A-5B The x, y, and z axes are shown as defined in three-dimensional space relative to the sensor 224 of the tracking system 220. The x and z axes extend horizontally and perpendicular to each other, while the y axis extends perpendicular to both the x and z axes. The x, y, and z axes intersect at the center point 218 where the sensor 224 is located.

[0073] method

[0074] The medical device 100 to be tested includes three separate needles 102 of needle types A, B, and C (see Table 3), namely, needles A.1, A.2, A.3, B.1, and B.2, totaling nine needles. As used herein, “true” distance is defined as the distance directly measured in three-dimensional space. As used herein, “computational distance” is defined as the distance measured in three-dimensional space by tracking system 220 (such as those described herein).

[0075] Test 1) Drop-out distance: As used herein, the drop-out distance is the maximum calculated distance between the magnetized needle 102 and the sensor 224 before the sensor 224 can no longer detect the presence of the needle 102. The test needle 102 is paired with the tracking system 220 and then removed from the sensor 224 until the tracking system 220 fails to detect the needle 102, i.e., becomes unpaired. The last known position of the needle 102 is then recorded from the tracking system 220.

[0076] Test 2) Pairing Distance: As used herein, the pairing distance is the maximum true distance between needle 102 and sensor 224, at which tracking system 220 can detect the presence of needle 102, i.e., successful pairing. Test needle 102 is positioned at predetermined locations defined by the x, y, and z axes, and successful pairing at these locations is recorded. Needle 102 is then positioned at different predetermined locations progressively farther away from sensor 224 until tracking system 220 can no longer pair with needle 102. The last known successful pairing distance for each needle 102 is recorded.

[0077] Test 3) Calculated Position Comparison with Actual Position: As used herein, the calculated position comparison with actual position is defined as the comparison between the actual position of needle 102 (e.g., measured by actual distance in 3D space) and the calculated position of needle 102 (e.g., measured by tracking system 220). Initially, needle 102 is positioned at a predetermined location defined by the x-axis, y-axis, and z-axis and paired with tracking system 220. Then, the actual position defined by the x-axis, y-axis, and z-axis is compared with the calculated position defined by tracking system 220, and the difference is recorded.

[0078] Test 4) Immunity to Magnetic Interference: As used herein, immunity is defined as the change caused by the presence of a magnetic interference source. The measured change is the difference between the true position and the calculated position. The needle 102 is paired with the tracking device 220 and positioned at a predetermined position defined by the x, y, and z axes. The true and calculated positions are recorded in the absence of a magnetic interference source. A constant magnetic interference source (e.g., a permanent magnet) is introduced, and the difference between the true and calculated positions is re-recorded and compared. In one embodiment, the magnetic interference source is farther from the sensor 224 than the needle 102.

[0079] data

[0080] Figures 6A-6D A bar chart illustrating the collected data is shown. The data comes from nine needles of each type, with three needles in total, as described in this article. Figure 6A The withdrawal distance of each needle is shown. Figure 6B The average pairing distance for each needle is shown. Figure 6C The difference between the actual and calculated positions of each needle is shown. Figure 6D The percentage change in calculated position error in the presence of magnetic interference sources is shown. It is important to note that the data provided herein are merely exemplary and should not be considered as limiting the scope of the invention.

[0081] result

[0082] Advantageously, it was found that the withdrawal and mating distances exhibited by needles formed from 17-7PH SS (e.g., needle C) were essentially twice that of needles formed from 304 SS (e.g., needles A and B). Furthermore, the 17-7PH SS needle (i.e., needle C) showed a 15- to 25-fold improvement in immunity to interference sources. Therefore, in the presence of magnetic interference sources, the calculated position change of the needle was less than 3%. In contrast, in the presence of the same magnetic interference sources, the calculated position change of the 304 SS needle ranged from 34% to 57%. The results of exemplary tests are shown in Table 4 below:

[0083] Table 4: Results of the Exemplary Test

[0084]

[0085] Based on these exemplary results, in terms of magnetic tracking measurements, needles made of 17-7PH SS are superior to those made of 304 stainless steel. Overall, needles made of 17-7PH SS offer a larger operating window when used with magnetic tracking systems and are much less affected by magnetic interference.

[0086] While specific embodiments have been disclosed herein, and in considerable detail, these specific embodiments are not intended to limit the scope of the concepts provided herein. Other applicability and / or modifications will likely occur to those skilled in the art, and are included in a broader sense. Accordingly, deviations from the specific embodiments disclosed herein are possible without departing from the scope of the concepts provided herein.

Claims

1. A trackable catheter placement system, characterized in that, include: A needle, which is formed of a magnetizable material and magnetized to generate a magnetic field, the magnetic field having one or both of a magnetic field strength and magnetic field characteristics that can be detected by the sensors of a tracking system; and A spring, formed of a non-magnetizable material and configured to exhibit the same mechanical properties, outer diameter, and bulk length dimensions as a spring formed of said magnetizable material. The non-magnetizable material mentioned above includes an alloy containing copper and beryllium. The magnetizable material mentioned above includes 17-7 precipitation-hardening stainless steel. The spring described herein comprises a wire core diameter of 0.0113 ± 0.001 inches. The spring described herein comprises between 30 and 37 effective coils, and The spring described therein includes a coil pitch angle between 12 and 16 degrees.

2. The traceable catheter placement system according to claim 1, characterized in that, The spring has a solid length between 0.45 inches and 0.49 inches.

3. The traceable catheter placement system according to claim 1, characterized in that, The spring has a spring diameter of 0.205 ± 0.005 inches.

4. The traceable catheter placement system according to claim 1, characterized in that, The spring includes three inactive coils at the distal end and two inactive coils at the proximal end.

5. The traceable catheter placement system according to claim 1, characterized in that, The spring includes a distal expansion diameter of 0.215 inches.

6. The traceable catheter placement system according to claim 1, characterized in that, The tracking system includes a passive magnetic tracking system configured to detect the magnetic field strength of the needle.

7. The traceable catheter placement system according to claim 1, characterized in that, The tracking system includes an electromagnetic tracking system configured to detect the magnetic field characteristics of the needle.

8. A method for tracking a catheter placement system, characterized in that, include: Provides a catheter placement system, the catheter placement system comprising: The needle is made of a magnetizable material; and A spring formed of a non-magnetizable material and configured to exhibit the same mechanical properties, outer diameter, and bulk length dimensions as a spring formed of said magnetizable material. The non-magnetizable material mentioned above includes an alloy containing copper and beryllium. The magnetizable material mentioned above includes 17-7 precipitation-hardening stainless steel. The spring described herein comprises a wire core diameter of 0.0113 ± 0.001 inches. The spring described herein comprises between 30 and 37 effective coils, and The spring described therein includes a coil pitch angle between 12 and 16 degrees; Magnetize the catheter placement system; The needle generates a magnetic field, which has magnetic field strength or magnetic field characteristics; and The magnetic field is detected by sensors in the tracking system.

9. The method according to claim 8, characterized in that, The spring has a solid length between 0.45 inches and 0.49 inches.

10. The method according to claim 8, characterized in that, The spring has a diameter of 0.205 ± 0.005 inches.

11. The method according to claim 8, characterized in that, The spring includes three inactive coils at the distal end and two inactive coils at the proximal end.

12. The method according to claim 8, characterized in that, The spring includes a distal expansion diameter of 0.215 inches.

13. The method according to claim 8, characterized in that, It also includes determining one of the needle's position, orientation, or trajectory.

14. The method according to claim 8, characterized in that, The tracking system includes a passive magnetic tracking system configured to detect the magnetic field strength of the needle.

15. The method according to claim 8, characterized in that, The tracking system includes an electromagnetic tracking system configured to detect the magnetic field characteristics of the needle.

16. A method for manufacturing a traceable medical device, characterized in that, include: A medical device is provided comprising a needle extending distally from a body and a spring disposed within the body, the needle being configured to enter a patient's vascular system and being formed of 17-7 precipitation-hardened stainless steel, and the spring being formed of an alloy comprising copper and beryllium and configured to exhibit the same mechanical properties, outer diameter, and bulk length dimensions as a spring formed of 17-7 precipitation-hardened stainless steel. The spring described herein comprises a wire core diameter of 0.0113 ± 0.001 inches. The spring described herein comprises between 30 and 37 effective coils, and The spring described therein includes a coil pitch angle between 12 and 16 degrees; A portion of the medical device is placed inside a magnetizer that includes magnetic elements; This exposes the needle and the spring to the magnetic field of the magnetic element; and The needle is magnetized to provide a first magnetic signal from the needle, and a small or no magnetic signal is provided from the spring.

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