Catheter Insertion System

Abstract

The catheter assembly includes a catheter and a stylet disposed within a lumen of the catheter. The lumen has a closed distal end. The stylet includes a sensor at the distal end of the stylet, the sensor located within a sensor pocket at the closed distal end of the lumen. A hole extending through the lumen wall between the sensor pocket and an exterior of the catheter defines an electrical pathway between the sensor and the patient's vasculature. A tapered distal portion of the catheter extends away from the distal end of the catheter. The sensor pocket is disposed along the tapered distal portion. A fluid opening extending between the lumen and an exterior of the catheter is disposed proximal to the sensor pocket. A coating portion of the stylet includes an electrically insulating coating, the coating portion being disposed adjacent to the fluid opening.

Description

[Background technology]

[0001] Proper placement of a central venous catheter ("CVC") is important to the function and life of the catheter. Current methods for positioning the tip of a CVC involve tracking both electrocardiographic changes in P waves and the tip of the CVC in three-dimensional space as the CVC is inserted into the vena cava. A stylet having a magnetic region is inserted into the CVC catheter to provide stiffness to the catheter during insertion and allow the magnetic region to be tracked using a magnetic field detector. Summary of the Invention [Problem to be solved by the invention]

[0002] However, there is a distance between the magnetic region of the stylet and the tip of the CVC, resulting in approximation of the tip of the CVC during placement. It would be beneficial for clinicians and patients to have a catheter insertion system that allows the tip of the stylet to be located closer to the tip of the CVC, while allowing for more accurate placement of the tip of the CVC within the pericardial vena cava, along with more rapid detection of P-wave electrocardiographic changes. Disclosed herein are catheter insertion systems, methods of use, and methods of manufacture that address the above. [Means for solving the problem]

[0003] Disclosed herein, according to some embodiments, is a catheter assembly including a catheter configured to be disposed within a patient's vasculature. The catheter includes: (i) a catheter tube configured to be disposed within a patient's vasculature and defining a distal end; (ii) a first lumen extending along the catheter tube, the first lumen in fluid communication with the first extension leg; and (iii) a second lumen extending along the catheter tube, the second lumen in fluid communication with the second extension leg. The catheter assembly further includes a stylet disposed within the second lumen, the stylet including a sensor configured to detect an electrical signal emanating from the patient. The sensor is located at a distal end of the stylet. The stylet is positioned with the second lumen such that the sensor is disposed within a sensor pocket of the second lumen. The sensor pocket is positioned at a closed distal end of the second lumen. A hole extending through the lumen wall of the second lumen defines a fluid pathway between the sensor pocket and the vasculature.

[0004] In some embodiments, the holes define an electrical pathway between the sensor and the vasculature. In some embodiments, the hole is positioned adjacent to the pocket. In some embodiments, the second lumen includes a fluid opening extending through the lumen wall. The fluid opening is disposed proximal to the hole.

[0005] In some embodiments, the catheter tube includes a tapered distal section extending proximally from a distal end of the catheter tube, the tapered distal section defining a first diameter distal to the catheter end and a second diameter at a proximal end of the tapered distal section, the second diameter being greater than the first diameter, and further, the pocket is disposed along the tapered distal section.

[0006] In some embodiments, the distance between the distal end and the pocket is less than half the length of the tapered distal portion, hi some embodiments, the distance between the distal end and the pocket is less than 2 cm.

[0007] In some embodiments, the stylet includes a coating extending along a coated portion of the stylet within the second lumen. The coating is electrically insulating. In some embodiments, the fluid opening is disposed adjacent to the coating portion. In some embodiments, the coating portion extends along the entire length of the stylet disposed within the second lumen. In some embodiments, the coating substantially occupies the annular space between the stylet and the lumen wall. In some embodiments, the coating includes a lubricant.

[0008] Also disclosed herein, according to some embodiments, is a method of positioning a catheter within the vasculature, comprising: (i) inserting a stylet into a lumen of the catheter; and (ii) advancing the stylet along the lumen such that a sensor of the stylet is disposed within a sensor pocket of the lumen. The lumen has a closed distal end. The sensor pocket is disposed at the closed distal end, and an aperture defining a fluid path extends through the lumen wall between the sensor pocket and an exterior of the catheter. The method further comprises advancing the catheter along the vasculature and interrupting advancement in response to an electrical signal detected by the sensor. The aperture defines an electrical path for the electrical signal.

[0009] In some embodiments, the method further includes visually observing the stylet disposed in the sensor pocket through the hole. In some embodiments of the method, the hole defines an electrical pathway between the sensor and the vasculature.

[0010] In some embodiments of the methods, the catheter includes a tapered distal section extending proximally from a distal end of the catheter. The tapered distal section defines a first diameter at the distal end and a second diameter at a proximal end of the tapered distal section. In such embodiments, the second diameter is greater than the first diameter and the hole is disposed along the tapered distal section.

[0011] In some embodiments of the method, the distance between the distal end and the hole is less than half the length of the tapered distal section. In some embodiments of the method, the distance between the distal end and the hole is less than 2 cm.

[0012] In some embodiments, the method further comprises removing the stylet from the lumen. Also disclosed herein, according to some embodiments, is a method of manufacturing a catheter assembly, including: (i) forming a catheter tube having a tapered distal portion extending proximally from a distal end of the catheter tube; (ii) forming a lumen extending along the catheter tube and having a closed distal end; (iii) forming a hole extending through the lumen wall between the closed distal end and an exterior of the catheter tube; and (iv) inserting a stylet into the lumen such that a sensor at a distal end of the stylet is disposed at the closed distal end.

[0013] In some embodiments of the method, the hole is disposed along the tapered distal portion. In some embodiments of the method, the distance between the distal end and the hole is less than half the length of the tapered distal portion. In some embodiments of the method, the distance between the distal end and the hole is less than 2 cm.

[0014] In some embodiments, the method further includes forming a fluid opening extending through a lumen wall between the lumen and an exterior of the catheter tube, the fluid opening being located proximal to the tapered distal section.

[0015] In some embodiments, the method of manufacture further includes coating the stylet with an insulating coating to define a coated portion of the stylet, the coated portion being disposed adjacent the fluid opening.

[0016] These and other features of the concepts provided herein will become more apparent to those of ordinary skill in the art upon consideration of the accompanying drawings and the following description, which describe in more detail certain embodiments of such concepts.

[0017] A more particular description of the present disclosure will be provided by reference to specific embodiments thereof, which are illustrated in the accompanying drawings, which depict only typical embodiments of the invention and therefore should not be considered as limiting its scope. Exemplary embodiments of the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which: [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 shows a perspective view of a catheter assembly including a catheter and a stylet, according to some embodiments. [Figure 2A] FIG. 1 shows a cross-sectional side view of a distal portion of a catheter including a sensor pocket, according to some embodiments. [Figure 2B] 2B illustrates a cross-sectional side view of FIG. 2A further including a stylet disposed within the lumen, according to some embodiments. [Figure 3A] 1A-1C show cross-sectional views of a distal portion of a catheter assembly illustrating an exemplary method of positioning a stylet within a lumen, according to some embodiments. [Figure 3B] 1A-1C show cross-sectional views of a distal portion of a catheter assembly illustrating an exemplary method of positioning a stylet within a lumen, according to some embodiments. [Figure 4] 1 shows a flowchart of an exemplary method of positioning a catheter assembly within the vasculature, according to some embodiments. [Diagram 5] 1 shows an exploded view of a catheter assembly according to some embodiments. [Figure 6] 1 shows a flowchart of an exemplary method of manufacturing a catheter assembly, according to some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Before disclosing some specific embodiments in more detail, it should be understood that the specific embodiments disclosed herein are not intended to limit the scope of the concepts provided herein. It should also be understood that a specific embodiment disclosed herein may have features that are easily separable from the specific embodiment and that may be combined or substituted in any way with features of any of the numerous other embodiments disclosed herein.

[0020] With regard to the terms used herein, it should also be understood that these terms are intended to describe certain embodiments and are not intended to limit the scope of the concepts provided herein. Ordinal numbers (e.g., first, second, third, etc.) are generally used to distinguish or identify different features or steps within a group of features or steps and do not provide sequential or numerical limitations. For example, the "first", "second", and "third" features or steps do not necessarily have to appear in that order, and a particular embodiment including such features or steps is not necessarily limited to three features or steps. Designations such as "left", "right", "up", "down", "front", "rear", etc. are used for convenience and do not imply, for example, a specific fixed position, orientation, or direction. Instead, such designations are used to reflect, for example, a relative position, orientation, or direction. The singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise.

[0021] With respect to "proximal," for example, the "proximal portion" or "proximal end portion" of a catheter disclosed herein includes the portion of the catheter intended to be near the clinician when the catheter is used on a patient. Similarly, for example, the "proximal length" of a catheter includes the length of the catheter intended to be near the clinician when the catheter is used on a patient. For example, the "proximal end" of a catheter includes the end of the catheter intended to be near the clinician when the catheter is used on a patient. The proximal portion, proximal end portion, or proximal length of a catheter can include the proximal end of the catheter. However, the proximal portion, proximal end portion, or proximal length of a catheter need not include the proximal end of the catheter. That is, unless the context suggests otherwise, the proximal portion, proximal end portion, or proximal length of a catheter is not the terminal portion or terminal length of the catheter.

[0022] With respect to "distal," for example, a "distal portion" or "distal end portion" of a catheter disclosed herein includes a portion of the catheter intended to be near or within a patient when the catheter is used with a patient. Similarly, for example, a "distal length" of a catheter includes a length of the catheter intended to be near or within a patient when the catheter is used with a patient. For example, a "distal end" of a catheter includes an end of the catheter intended to be near or within a patient when the catheter is used with a patient. A distal portion, end portion, or length of a catheter can include the distal end of the catheter. However, a distal portion, end portion, or length of a catheter need not include the distal end of the catheter. That is, unless the context suggests otherwise, a distal portion, end portion, or length of a catheter is not a terminal portion or length of the catheter.

[0023] Any method disclosed herein includes one or more steps or actions for carrying out the method described. The steps and / or actions of the method may be interchanged with one another. In other words, the order and / or use of certain steps and / or actions may be modified unless a specific order of steps or actions is required to properly implement the embodiment. Furthermore, only subroutines or portions of the methods described herein may be separate methods within the scope of the present disclosure. In other words, some methods may include only some of the steps described in a more detailed method. In addition, all embodiments disclosed herein are combinable and / or interchangeable unless otherwise stated or unless such combination or interchange is contrary to the described enablement of any embodiment.

[0024] The phrases "connected to," "coupled to / with," and "in communication with" refer to any form of interaction between two or more elements, including but not limited to mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interaction. Two components may be connected to one another even if they are not in direct contact with one another. For example, two components may be coupled to one another through an intermediate component.

[0025] 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. FIG. 1 shows a perspective view of a catheter assembly 100 according to some embodiments. The catheter assembly 100 includes a catheter 101. In some embodiments, the catheter 101 includes a central venous catheter ("CVC") having a hub 102 coupled to a catheter tube 104 that extends to a distal end 110. In the illustrated embodiment, the catheter 101 includes a first lumen 106 and a second lumen 108. In other embodiments, the catheter 101 may include three or more lumens. The hub 102 is coupled to a first extension leg 112 and a second extension leg 116. The first extension leg 112 includes a first extension leg lumen 114 in fluid communication with the first lumen 106, and the second extension leg 116 includes a second extension leg lumen 118 in fluid communication with the second lumen 108. The catheter assembly 100 further includes a stylet 130 that is inserted into the second extension leg lumen 118 and the second lumen 108. The stylet 130 can be configured to impart stiffness to the catheter 101 to aid in positioning the catheter 101 within the vasculature.

[0026] The stylet 130 includes a sensor 138 (e.g., an electrode) configured to detect electrical signals within the patient's body, such as, for example, an ECG signal including P waves. The sensor 138 may be located directly adjacent to a distal end of the stylet 130, as described further below. The sensor 138 is generally configured to enable accurate placement of the distal tip 110 of the catheter tube 104. For example, the medical device tracking system may be configured to determine a location of the sensor 138 within a vasculature 180, for example having the superior vena cava, based on the detected P-wave signal. When the sensor 138 is located directly adjacent to the distal end of the stylet 130, and when the distal end of the stylet 130 may be located adjacent to the distal end 110 of the catheter 101, the medical device tracking system can determine the location of the distal end 110 within the vasculature 180. In some embodiments, the stylet 130 may further include a magnetic region 134 disposed adjacent a distal end of the stylet 130, the magnetic region 134 including several (e.g., one, two, three, or more) magnets 136 configured to generate one or more magnetic fields. In such embodiments, the medical device tracking system may be configured to track the position of the magnetic region 134 in three-dimensional space based on the one or more magnetic fields.

[0027] 2A shows a cross-sectional side view of a distal end portion 105 of a catheter tube 104, according to some embodiments. A first lumen 106 and a second lumen 108 are shown. The catheter tube 104 generally defines a long portion 104A extending proximally from a transition point 121 and a tapered distal portion 120 extending distally from the transition point 121. The long portion 104A defines a substantially constant outer diameter 122, and the tapered distal tip portion 120 defines a conical (or tapered) shape. The tapered distal tip portion 120 includes the outer diameter 122 at the transition point 121 and a tip diameter 124 at the distal end 110. The tip diameter 124 is less than the outer diameter 122. The transition point 121 is located a transition point distance 126 from the distal end 110 , and thus the transition point distance 126 defines the length of the tapered distal tip portion 120 .

[0028] The second lumen 108 extends along the distal end portion 105 and defines a closed distal end 108A located a distance 142 away from the distal end 110. In the illustrated embodiment, the distance 142 may be less than about 2 cm, 1.5 cm, 1.0 cm, or 0.5 cm. In some embodiments, the distance between the distal end 110 and the closed distal end 108A is less than half the length of the tapered distal portion 120. The aperture 158 extends through the wall 103 of the catheter tube 104 such that, in use, the second lumen 108 is in fluid communication with blood within the vasculature 80. The aperture 158 is disposed adjacent the closed distal end 108A. The closed distal end 108A may define a sensor pocket 150 configured to receive the distal end of the stylet 130. The aperture 158 defines fluid communication between the sensor pocket 150 and the blood during use.

[0029] In the illustrated embodiment, the catheter tube 104 may include a side opening 160 extending through the wall 103. Such a side opening 160 may be configured for delivery of a drug or any other use associated with the catheter 101. The side opening 160 may be located proximal to the bore 158 and / or the tapered distal tip portion 120.

[0030] 2B illustrates a cross-sectional view of the distal tip portion 105 of FIG. 6 with the stylet 130 disposed within the second lumen 108, according to some embodiments. In some embodiments, the second lumen 108 may be configured to slidably receive the stylet 130 such that the distal end 135 of the stylet 130 is disposed adjacent the closed distal end 108A, i.e., within the sensor pocket 150. Because the sensor 138 is disposed adjacent the distal end 135 of the stylet 130, the sensor 138 is disposed within the sensor pocket 150. Additionally, during use, the sensor 138 is in fluid communication with blood via the hole 158. Because blood is conductive, the sensor 138 is electrically coupled to the blood.

[0031] In some embodiments, the stylet 130 may include an electrically insulating coating 133. In some embodiments, the coating 133 may extend along a portion of the stylet 130 adjacent the side opening 160 so as to electrically insulate the sensor 138 from blood via the side opening 160. In some embodiments, the coating 133 extends along substantially the entirety of the stylet 130. In some embodiments, the coating 133 may include a lubricant. In some embodiments, the coating 133 may occupy substantially the annular space between the stylet 130 and the second lumen 108.

[0032] In summary, the catheter assembly 100 includes a stylet 130 having a sensor 138 disposed within the second lumen 108 of the catheter tube 104 such that the sensor 138 is disposed adjacent the distal end 110 of the catheter tube 104. During placement of the catheter 101 within the vasculature 180, the sensor 138 is electrically connected to the blood via a hole 158 disposed adjacent the distal end 110 such that the sensor 138 can detect electrical signals (e.g., p-waves). An insulating coating 133 is disposed along the stylet 130 to prevent electrical connection between the blood and the sensor 138 via any electrical path other than the hole 158.

[0033] 3A-3B are cross-sectional views illustrating an exemplary method of positioning a stylet 130 within the second lumen 108 of the catheter 101, according to some embodiments. Figure 3A shows the stylet 130 partially inserted within the second lumen 108. As shown in Figure 3A, the stylet 130 may be slidably inserted within the second lumen 108 of the catheter 101.

[0034] 3B shows the stylet 130 fully inserted into the second lumen 108. As shown in FIG. 3B, the stylet 130 may be placed in the sensor pocket 150 prior to placing the catheter 101 in the vasculature 180. In some embodiments, a user may visually determine that the stylet 130 is placed in the sensor pocket 150 by visually observing the stylet 130 through the hole 158. Once the stylet 130 is in the sensor pocket 150, the stylet 130 may be rotated so that the sensor 138 faces the hole 158 to increase the ability of the sensor 138 to detect P-waves through the hole 158.

[0035] 4 shows a flowchart of an exemplary method 200 of placing a catheter within the vasculature, which may include all or any subset of the following actions, steps, or processes, according to some embodiments: The method 200 may include inserting a stylet into a lumen of the catheter (block 210), the lumen having a closed distal end.

[0036] The method 200 may further include advancing the stylet along the lumen such that a sensor of the stylet is disposed within a sensor pocket of the lumen (block 220). The sensor pocket is disposed at a closed distal end of the lumen, and the bore defines a fluid path extending through the lumen wall between the sensor pocket and an exterior of the catheter. In some embodiments of the method 200, the catheter includes a tapered tip distal section extending proximally from the distal end of the catheter. The tapered distal tip section defines a first diameter at the distal end and a second diameter at a proximal end of the tapered distal tip section. In such embodiments, the second diameter is greater than the first diameter, and the bore is disposed along the tapered distal tip section. In some embodiments of the method 200, the distance between the distal end and the bore is less than half the length of the tapered distal section. In some embodiments of the method 200, the distance between the distal end and the hole is less than 2 cm.

[0037] The method 200 may further include visually observing the stylet disposed within the sensor pocket through the hole (Block 230). The method 200 may further include advancing the catheter along the vasculature (240). The method 200 may further include interrupting advancement in response to an electrical signal detected by the sensor (Block 250). The hole defines an electrical path for the electrical signal. The method 200 may further include removing the stylet from the lumen (Block 260).

[0038] FIG. 5 shows an exploded view of a catheter assembly 100 with a distal end portion 105 shown in cross section, according to some embodiments. In some embodiments, a manufacturing method may be used to manufacture a catheter 101 having a sensor pocket 150 therein and a stylet 130 having a sensor 138 and / or a magnetic region 134. A catheter tube 104 may be formed including first and second lumens 106 / 108. The second lumen 108 has a closed distal end 106A. In some embodiments, the catheter tube 104 may be formed by extrusion, 3D printing, injection molding, etc. The catheter tube 104 includes a first catheter tube diameter 122 and a second catheter tube diameter 124. The catheter tube 104 may include a tapered distal tip portion 120 that tapers from the first catheter tube diameter 122 to the second catheter tube diameter 124.

[0039] The sensor pocket 150 may be formed in the closed distal end 108A of the second lumen 108. In some embodiments, the second lumen 108 including the sensor pocket 150 may be extruded, 3D printed, injection molded, etc. In the illustrated embodiment, the closed distal end 108A and associated sensor pocket 150 may be located along the tapered distal tip portion 120.

[0040] Once the sensor pocket 150 is formed in the catheter tube 104, a hole 158 may be formed. The hole 158 may provide fluid communication between the sensor pocket 150 and the exterior of the catheter tube 104. In some embodiments, the hole 158 may be formed along the tapered distal tip portion 120. In some embodiments, the hole 158 may be drilled or cut through the exterior surface into the sensor pocket 150, or the like.

[0041] An opening 160 may be formed. In some embodiments, the opening 160 may be formed simultaneously with the hole 158 or after the hole 158. In some embodiments, the opening 160 may be formed proximal to the hole 158. In some embodiments, the opening 160 may be formed proximal to the tapered distal tip portion 120.

[0042] Once the sensor pocket 150, the hole 158, and the opening 160 are fully formed in the catheter tube 104, the catheter 101 can be assembled. The catheter tube 104 may be coupled to the hub 102 and placed in fluid communication with the first and second extension legs 112 / 116 (see FIG. 1).

[0043] The stylet 130 may be formed with a magnet 136 coupled to the stylet 130 to define a magnetic region 134. A sensor 138 is coupled to the stylet 130. In some embodiments, the stylet 130 may include a stylet length extending between a closed distal end 108A of the second lumen 108 and a proximal end of the second extension leg 116. A coating 133 may be applied to the stylet 130 along a coating region 133A of the stylet 130.

[0044] 6 shows a flowchart of an exemplary method 300 of manufacturing the catheter assembly 100, which may include all or any subset of the following actions, steps, or processes, according to some embodiments. The method 300 may include forming a catheter tube having a tapered distal portion extending proximally from a distal end of the catheter tube (Block 310).

[0045] The method 300 may further include forming a lumen extending along the catheter tube (Block 320), the lumen having a closed distal end. The method 300 may further include forming a hole extending through the lumen wall between the closed distal end and an exterior of the catheter tube (Block 330). In some embodiments of the method 300, the hole is disposed along the tapered distal tip section. In some embodiments of the method 300, the distance between the distal end of the catheter tube and the hole is less than half the length of the tapered distal tip section. In some embodiments of the method 300, the distance between the distal end and the hole is less than 2 cm.

[0046] The method 300 may further include inserting (340) a stylet into the lumen such that a sensor at a distal end of the stylet is disposed at the closed distal end. The method 300 may further include forming (350) a fluid opening extending through a lumen wall between the lumen and an exterior of the catheter tube, the fluid opening being located proximal to the tapered distal tip portion.

[0047] The method 300 may further include coating the stylet with an insulating coating (Block 360) to define a coated portion of the stylet, the coated portion being disposed adjacent the fluid opening.

[0048] Some specific embodiments are disclosed herein, and although the specific embodiments are disclosed in some detail, the specific embodiments are not intended to limit the scope of the concept provided herein. Additional adaptations and / or modifications may be apparent to those skilled in the art, and the broader aspects also encompass these adaptations and / or modifications. Thus, one may deviate from the specific embodiments disclosed herein without departing from the scope of the concept provided herein.

Claims

1. 1. A catheter assembly comprising: A catheter, a catheter tube configured to be placed within a patient's vasculature and defining a distal end; a first lumen extending along the catheter tube, the first lumen in fluid communication with the first extension leg; a second lumen extending along the catheter tube, the second lumen in fluid communication with the second extension leg; a catheter comprising: a stylet disposed within the second lumen, the stylet including a sensor configured to detect electrical signals emanating from the patient; the sensor is located at the distal end of the stylet; the sensor is disposed within a sensor pocket of the second lumen; the sensor pocket is positioned at a closed distal end of the second lumen; a hole extending through a lumen wall of the second lumen defining a fluid pathway between the sensor pocket and the vasculature; Catheter assembly.

2. The assembly of claim 1 , wherein the aperture defines an electrical pathway between the sensor and the vasculature.

3. The assembly of claim 1 or 2, wherein the aperture is positioned adjacent to the sensor pocket.

4. the catheter tube includes a tapered distal section extending proximally from the distal end of the catheter tube, the tapered distal section defining a first diameter at the distal end and a second diameter at a proximal end of the tapered distal section; the second diameter is greater than the first diameter, The assembly of claim 1 or 2, wherein the sensor pocket is disposed along the tapered distal portion.

5. The assembly of claim 4 , wherein the distance between the distal end of the catheter tube and the sensor pocket is less than half the length of the tapered distal section.

6. The assembly of claim 4 , wherein the distance between the distal end of the catheter tube and the sensor pocket is less than 2 cm.

7. the stylet includes a coating extending along a coated portion of the stylet within the second lumen; 3. The assembly of claim 1 or 2, wherein the coating is electrically insulating.

8. the second lumen includes a fluid opening extending through the lumen wall; The assembly of claim 1 or 2, wherein the fluid opening is located proximal to the aperture.

9. The assembly of claim 8 , wherein the coating portion is disposed adjacent the fluid opening.

10. The assembly of claim 8 , wherein the coating portion extends along the entire length of the stylet disposed within the second lumen.

11. The assembly of claim 8 , wherein the coating substantially occupies an annular space between the stylet and the lumen wall.

12. The assembly of claim 8 , wherein the coating comprises a lubricant.

13. 1. A method of manufacturing a catheter assembly, comprising: forming a catheter tube having a tapered distal section extending proximally from a distal end of the catheter tube, the tapered distal section extending proximally from the distal end of the catheter tube, the tapered distal section defining a first diameter at the distal end of the catheter tube and a second diameter at a proximal end of the tapered distal section, the second diameter being larger than the first diameter; forming a lumen extending along the catheter tube and having a closed distal end; forming a hole extending through a lumen wall between the closed distal end and an exterior of the catheter tube; and inserting a stylet into the lumen such that a sensor at a distal end of the stylet is located at the closed distal end.

14. The method of claim 13 , wherein the holes are disposed along the tapered distal portion.

15. 15. The method of claim 14, wherein the distance between the distal end of the catheter tube and the bore is less than half the length of the tapered distal section.

16. 16. The method of claim 14 or 15, wherein the distance between the distal end of the catheter tube and the hole is less than 2 cm.

17. 16. The method of claim 13, further comprising forming a fluid opening extending through a lumen wall between the lumen and the exterior of the catheter tube, the fluid opening being located proximal to the tapered distal section.

18. 16. The method of claim 13, further comprising coating the stylet with an insulating coating to define a coated portion of the stylet, the coated portion being positioned adjacent the fluid opening.

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