Medical tubes and methods of manufacture

Abstract

To provide medical tubes and methods of manufacturing medical tubes.SOLUTION: A tube may be a composite structure made of two or more distinct components that are spirally wound to form an elongate tube. For example, one of the components may be a spirally wound elongate hollow body, and the other component may be an elongate structural component also spirally wound between turns of the spirally wound hollow body The tube need not be made from distinct components, however. For instance, an elongate hollow body formed (e.g., extruded) from a single material may be spirally wound to form an elongate tube. The elongate hollow body itself may in a transverse cross-section have a thin wall portion and a relatively thicker or more rigid reinforcement portion. The tubes can be incorporated into a variety of medical circuits or may be employed for other medical uses.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure generally relates to tubes suitable for medical use, and more particularly to tubes used in medical circuits suitable for providing gas to and / or removing gas from a patient, such as positive airway pressure (PAP), respirators (ventilators), anesthesia, ventilators (artificial ventilators), and insufflation systems.

Background Art

[0002] In medical circuits, various components convey warm gas and / or humidified gas to and from a patient. For example, in some respiratory circuits such as PAP and assisted breathing circuits, the gas inhaled by the patient is delivered from a heater-humidifier via an inspiratory tube. In another example, a tube can deliver humidified gas (generally CO2) intraperitoneally in an insufflation circuit. This can help prevent "drying" of the patient's internal organs and can shorten the time required for recovery from surgery. With non-heated tubes, significant heat loss occurs due to ambient cooling. This cooling can result in undesirable condensation or "rainout" along the length of the tube carrying warm, humid air. There is still a need for tubes that are insulated against heat loss and that enable, for example, improved temperature and / or humidity control in medical circuits.

Summary of the Invention

Means for Solving the Problems

[0003] In this specification, medical tubes and methods for manufacturing medical tubes are disclosed in various embodiments. In some embodiments, the tube may be a composite structure made from two or more separate components that are helically wound to form an elongated tube. For example, one of the components may be a helically wound elongated hollow body, and the other component may be an elongated structural component similarly helically wound between the windings of the helically wound hollow body. In other embodiments, it is not necessary to make the tube from separate components. For example, an elongated tube may be formed by helically winding an elongated hollow body made from a single material (e.g., extruded). The elongated hollow body itself may have, in cross-section, thin wall portions and reinforcing portions that are relatively thicker or more rigid. The tube may be incorporated into various medical circuits or used for other medical purposes.

[0004] In at least one embodiment, the composite tube may include a first elongated member, which is helically wound to form at least partially an elongated tube having a longitudinal axis, a lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen. A second elongated member may be helically wound and joined between adjacent windings of the first elongated member, the second elongated member forming at least a portion of the lumen of the elongated tube. The names “first elongated member” and “second elongated member” do not necessarily include any order, such as the order in which the components are assembled. As described herein, the first and second elongated members may also be part of a single tubular element.

[0005] In various embodiments, the components described above have one, some, or all of the characteristics described elsewhere in this disclosure, along with the following characteristics.

[0006] The first elongated member may be a tube. In its longitudinal section, the first elongated member may form a plurality of hemispherical bodies (bubbles) with a flat surface in the lumen. Adjacent hemispherical bodies may be separated by a gap above the second elongated member, i.e., they may not be directly connected to each other. The hemispherical bodies may have perforations. The second elongated member may have a longitudinal section that widens adjacent to the lumen and narrows radially from the lumen. In particular, the second elongated member may have a longitudinal section that is approximately triangular, approximately T-shaped, or approximately Y-shaped. One or more conductive filaments may be embedded or sealed in the second elongated member. One or more conductive filaments may be heating filaments (or more specifically, resistance heating filaments) and / or sensing filaments. The tube may comprise pairs of conductive filaments, such as two or four conductive filaments. Pairs of conductive filaments may form a connecting loop at one end of the composite tube. One or more conductive filaments may be spaced apart from the lumen wall. In at least one embodiment, the second elongated member may have a longitudinal cross-section that is substantially triangular, substantially T-shaped, or substantially Y-shaped, and one or more conductive filaments may be embedded or encapsulated on both sides of the triangular, T-shaped, or Y-shaped portion of the second elongated member.

[0007] The components described above, according to any or all of the embodiments described above, can be incorporated into medical circuit components, inhalation tubes, exhalation tubes, PAP components, air supply circuits, diagnostic components, or surgical components, although they may have other uses.

[0008] A method for manufacturing a composite tube is also disclosed. The resulting tube may have one, some, or all of the properties described above or anywhere in this disclosure. In at least one embodiment, the method includes the step of providing a first elongated member having a hollow body and a second elongated member configured to provide structural support to the first elongated member. The second elongated member is helically wound around a mandrel such that opposing side edges of the second elongated member are spaced apart over adjacent wraps, thereby forming a second elongated member helix. The first elongated member is helically wound around the second elongated member helix, with some portions of the first elongated member overlapping adjacent wraps of the second elongated member helix, and some portions of the first elongated member positioned adjacent to the mandrel in the space between the wraps of the second elongated member helix, thereby forming the first elongated member helix.

[0009] In various embodiments, the methods described above may include one, some, or all of the following: The method may include supplying air to the end of the first elongated member at a pressure higher than atmospheric pressure. The method may include cooling the second elongated member helix and the first elongated member helix to form a composite tube having a lumen extending along the longitudinal axis and a hollow space surrounding the lumen. The method may include forming the first elongated member. The method may include extruding the first elongated member using a first extruder. The method may include forming the second elongated member. The method may include extruding the second elongated member using a second extruder. The second extruder may be configured to encapsulate one or more conductive filaments in the second elongated member. The step of forming the second elongated member may include embedding the conductive filaments in the second elongated member. The conductive filaments may be nonreactive with the second elongated member. The conductive filaments may include aluminum or copper alloys or other conductive materials. The method may further include the step of forming a connecting loop of a pair of conductive filaments at one end of the composite tube. The first extruder may be separate from the second extruder.

[0010] Medical tubing is also disclosed. In at least one embodiment, the tubing comprises an elongated hollow body that is wound helically to form an elongated tube having a longitudinal axis, a lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen, the hollow body having a wall that defines at least a portion of the hollow body in a longitudinal section. The tubing may further comprise reinforcing portions that are helically arranged between adjacent windings of the elongated hollow body and extend along the length of the elongated hollow body, the reinforcing portions forming a portion of the lumen of the elongated tube. The reinforcing portions may be relatively thicker or more rigid than the wall of the elongated hollow body.

[0011] In various embodiments, the tube described above has one, some, or all of the properties described elsewhere in this disclosure, along with the following properties: The reinforcing portion can be formed from the same material piece as the elongated hollow body. The elongated hollow body may have two reinforcing portions on either side of the elongated hollow body in cross-section, and the helical windings of the elongated hollow body join adjacent reinforcing portions to each other such that the opposing edges of the reinforcing portions contact the adjacent windings of the elongated hollow body. The opposing side edges of the reinforcing portions may overlap the adjacent windings of the elongated hollow body. The reinforcing portion can be fabricated from a separate material piece from the elongated hollow body. The hollow body may form a plurality of hemispherical bodies in longitudinal section, with a flat surface in the lumen. The hemispherical bodies may have perforations. The medical tube may also comprise one or more conductive filaments embedded or encapsulated in the reinforcing portion. The conductive filaments may be heating filaments and / or sensing filaments. The medical tube may comprise two conductive filaments, with one conductive filament embedded or encapsulated in each of the reinforcing portions. A medical tube may comprise two conductive filaments positioned on only one side of an elongated hollow body. A pair of conductive filaments can be connected to form a connecting loop at one end of the elongated tube. One or more filaments may be positioned at a distance from the inner lumen wall.

[0012] The tubes described above, according to any or all of the embodiments described above, can be incorporated into medical circuit components, inhalation tubes, exhalation tubes, PAP components, air supply circuits, diagnostic components, or surgical components, although they may have other uses.

[0013] A method for manufacturing a medical tube is also disclosed. In at least one embodiment, the method includes the step of winding an elongated hollow body helically around a mandrel to form an elongated tube having a longitudinal axis, a lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen, wherein the elongated hollow body has, in cross-section, a wall defining at least a portion of the hollow body and two reinforcing portions on either side of the elongated body that form part of the wall of the lumen, the two reinforcing portions being relatively thicker or more rigid than the wall defining at least a portion of the hollow body. The method may further include the step of joining adjacent reinforcing portions to each other such that the opposing edges of the reinforcing portions are in contact on adjacent windings of the elongated hollow body.

[0014] In various embodiments, the following characteristics may be present along with one, some, or all of any other characteristics described elsewhere in this disclosure. The edges of reinforcing portions may be overlapped by joining adjacent reinforcing portions to each other. The method may further include the step of supplying air at a pressure higher than atmospheric pressure to the end of an elongated hollow body. The method may further include the step of cooling the elongated hollow body to join adjacent reinforcing portions to each other. The method may further include the step of extruding the elongated hollow body. The method may further include the step of embedding conductive filaments in the reinforcing portions. The method may further include the step of forming a connecting loop of a pair of conductive filaments at one end of an elongated tube.

[0015] For the purpose of summarizing the present invention, several aspects, advantages, and novel features of the present invention have been described herein. It should be understood that not all of these advantages can necessarily be achieved by any particular embodiment of the present invention. Therefore, the present invention can be embodied or practiced in a manner that achieves or maximizes one advantage or set of advantages as taught herein, without necessarily achieving other advantages as taught or suggested herein.

[0016] Here, with reference to the drawings, exemplary embodiments for implementing various features of the disclosed systems and methods will be described. The drawings and the related descriptions are provided to illustrate the embodiments rather than to limit the scope of the present disclosure.

Brief Description of the Drawings

[0017] [Figure 1] A schematic diagram of a medical circuit incorporating one or more medical tubes is shown. [Figure 2A] A side view of a part of an example of a composite tube is shown. [Figure 2B] A longitudinal section of a top tube similar to the example of the composite tube in FIG. 2A is shown. [Figure 2C] Another longitudinal section showing the first elongate member of the composite tube is shown. [Figure 2D] Another longitudinal section of the top of the tube is shown. <O000074> [Figure 2E] Another longitudinal section of the top of the tube is shown. [Figure 3A] A cross-section of the second elongate member of the composite tube is shown. [Figure 3B] Another cross-section of the second elongate member is shown. [Figure 3C] Another example of a second elongate member is shown. [Figure 3D] Another example of a second elongate member is shown. [Figure 3E] Another example of a second elongate member is shown. [Figure 3F] Another example of a second elongate member is shown. [[ID=A3]] [Figure 3G] Another example of a second elongate member is shown. [Figure 4A] Aspects in a method of forming a composite tube are shown. [Figure 4B] A helically wound second elongate member is shown. [Figure 4C] Another aspect in a method of forming a composite tube is shown. [Figure 4D] Another aspect in a method of forming a composite tube is shown. [Figure 4E]Another embodiment of a method for forming a composite tube is shown. [Figure 4F] Another embodiment of a method for forming a composite tube is shown. [Figure 5A-B] Another example is shown, illustrating a single, elongated hollow body that is spirally wound to form a medical tube. [Figure 5C-F] Other examples of single, elongated hollow bodies that are spirally wound to form a medical tube are shown. [Figure 6] An example of a medical circuit according to at least one embodiment is shown. [Figure 7] An air supply system according to at least one embodiment is shown. [Figure 8] This is a schematic diagram of a coaxial tube according to at least one embodiment. [Figure 9A-C] An example of the shape of the first elongated member configured to improve thermal efficiency is shown. [Figure 9D-F] An example of a filament arrangement configured to improve thermal efficiency is shown. [Figure 10A-C] An example of lamination of the first elongated member is shown. [Figure 11A-D] The radius of curvature characteristics of tubes in various embodiments are demonstrated. [Modes for carrying out the invention]

[0018] Throughout the drawings, reference numbers are reused to indicate correspondences between referenced (or similar) elements. Furthermore, the first digit of each reference number indicates the drawing in which that element first appears.

[0019] Details of several exemplary embodiments for carrying out the apparatus and methods described herein are described below with reference to the figures. The present invention is not limited to these described embodiments.

[0020] A breathing circuit with one or more medical tubes. To better understand this disclosure, we first refer to Figure 1. Figure 1 shows a breathing circuit according to at least one embodiment, comprising one or more medical tubes. Tube is a broad term, and its ordinary and customary meaning should be given to those skilled in the art (i.e., not limited to a special or specialized meaning), and includes non-cylindrical passages without limitation. Some embodiments may incorporate composite tubes, which can generally be defined as a tube comprising two or more parts, or in some embodiments, two or more components, as will be described in more detail later. Such breathing circuits may be continuous positive airway pressure (PAP) systems, variable PAP systems, or two-stage PAP systems, or other forms of respiratory therapy.

[0021] The gas can be delivered to the circuit in Figure 1 as follows: Dry gas travels from the ventilator / blower 105 to the humidifier 107, which humidifies the dry gas. The humidifier 107 is connected via a port 111 to the inlet 109 (the end that receives the humidified gas) of the inspiratory tube 103, thereby supplying the humidified gas to the inspiratory tube 103. The inspiratory tube is a tube configured to deliver the respiratory gas to the patient and may be made from a composite tube, as will be described in more detail later. The gas flows through the inspiratory tube 103 to the outlet 113 (the end that discharges the humidified gas), and then through the patient interface 115 connected to the outlet 113 to the patient 101.

[0022] The exhalation tube 117 is also connected to the patient interface 115. The exhalation tube is configured to keep the exhaled humidified gas away from the patient. Here, the exhalation tube 117 returns the exhaled humidified gas from the patient interface 115 to the ventilator / blower 105.

[0023] In this example, dry gas enters the ventilator / blower 105 through the vent 119. A fan 121 can facilitate the gas flow to the ventilator / blower by drawing air or other gas through the vent 119. The fan 121 can be, for example, a variable-speed fan, in which case an electronic controller 123 controls the fan speed. In particular, the functions of the electronic controller 123 can be controlled by an electronic master controller 125 according to a user-set required value (pre-set value) of pressure or fan speed via input from the master controller 125 and a dial 127.

[0024] The humidifier 107 comprises a humidifying chamber 129 containing a certain volume of water 130 or other suitable humidifying liquid. Preferably, the humidifying chamber 129 is removable from the humidifier 107 after use. Removability allows for easier sterilization or disposal of the humidifying chamber 129. However, the humidifying chamber 129 portion of the humidifier 107 can be an integral structure. The body of the humidifying chamber 129 can be formed from a non-conductive glass or plastic material. However, the humidifying chamber 129 can also include conductive components. For example, the humidifying chamber 129 may have a highly thermally conductive base (e.g., an aluminum base) that is in contact with or associated with the heater plate 131 of the humidifier 107.

[0025] The humidifier 107 may also include an electronic control unit. In this example, the humidifier 107 includes an electronic, analog, or digital master controller 125. Preferably, the master controller 125 is a microprocessor-based controller that executes computer software commands stored in associated memory. For example, in response to a humidity value input or a temperature value input and other inputs set by the user via the user interface 133, the master controller 125 determines when (or to what level) the heater plate 131 should be energized to heat the water 130 in the humidification chamber 129.

[0026] Any suitable patient interface 115 can be incorporated. "Patient interface" is a broad term, and its ordinary and customary meaning should be given to those skilled in the art (i.e., not limited to any special or specialized meaning), and includes, without limitation, masks (e.g., tracheal masks, face masks, and nasal masks), cannulas, and nasal pillows. A temperature probe 135 can be connected to the inspiratory tube 103 near the patient interface 115 or to the patient interface 115 itself. The temperature probe 135 monitors the temperature near or at the patient interface 115. Using a heating filament (not shown) associated with the temperature probe, the temperature of the inspiratory tube 103 and / or the patient interface 115 can be adjusted to raise the temperature above the saturation temperature, thereby reducing the likelihood of undesirable condensation.

[0027] In Figure 1, the discharged humidified gas is returned from the patient interface 115 through the exhalation tube 117 to the ventilator / blower 105. The exhalation tube 117 can be a composite tube, as will be described in more detail later. However, the exhalation tube 117 can also be a medical tube, as has been known in the art for some time. In either case, a temperature probe and / or heating filament can be incorporated into the exhalation tube 117 to reduce the possibility of condensation, as described above with respect to the inhalation tube 103. Furthermore, the exhalation tube 117 does not need to return the discharged gas to the ventilator / blower 105. Alternatively, the discharged humidified gas can be sent directly to the ambient environment or to other auxiliary equipment such as an air scrubber / filter (not shown). In some embodiments, the exhalation tube is omitted entirely.

[0028] Composite tube Figure 2A shows a partial side view of an example composite tube 201. Generally, the composite tube 201 comprises a first elongated member 203 and a second elongated member 205. Member is a broad term, and it should be given its ordinary and customary meaning to those skilled in the art (i.e., not limited to a special or specialized meaning), and includes, without limitation, integrated parts, integrated components and separate components. Thus, although Figure 2A shows an embodiment made from two separate components, it will be understood that in other embodiments (such as those described later in Figures 5A to 5D), the first elongated member 203 and the second elongated member 205 can also represent regions within a tube formed from a single material. Thus, the first elongated member 203 can represent a hollow portion of the tube, and the second elongated member 205 can represent a structural support or reinforcing portion of the tube that adds structural support to the hollow portion. The hollow portion and the structural support portion can have a helical structure, as described herein. The composite tube 201 can be used to form the inhalation tube 103 and / or the exhalation tube 117 as described above, a coaxial tube as described later, or any other tube as described elsewhere in this disclosure.

[0029] In this example, the first elongated member 203 includes a hollow body that is helically wound to form at least partially an elongated tube having a lumen 207 extending along the longitudinal axes LA-LA and LA-LA. In at least one embodiment, the first elongated member 203 is a tube. Preferably, the first elongated member 203 is flexible. Furthermore, the first elongated member 203 is preferably transparent, or at least translucent or semi-opaque. Some degree of light transmittance allows a caregiver or user to inspect the lumen 207 for blockages or contaminants or to check for the presence of moisture. Various plastics, including medical plastics, are suitable for the body of the first elongated member 203. Examples of suitable materials include polyolefin elastomers, polyether block amides, thermoplastic copolyester elastomers, EPDM-polypropylene mixtures, and thermoplastic polyurethanes.

[0030] The hollow structure of the first elongated member 203 contributes to the thermal insulation properties of the composite tube 201. The insulated tube 201 is desirable to prevent heat loss as described above. This allows the tube 201 to deliver gas from the heater-humidifier to the patient while maintaining the controlled state of the gas with minimal energy consumption.

[0031] In at least one embodiment, the hollow portion of the first elongated member 203 is filled with gas. The gas has low thermal conductivity (2.62 × 10⁻¹⁰ at 300K). -2 Air is desirable because it is very low cost (W / m·K). Gases with a higher viscosity than air can also be used advantageously because their higher viscosity reduces convective heat transfer. For example, argon (17.72 × 10⁻¹⁰ at 300K) -3 W / m·K), krypton (9.43 × 10 at 300K) -3 (W / m·K) and xenon (5.65 × 10 at 300K) -3Gases such as W / m·K can improve the thermal insulation performance. Each of these gases is non-toxic, chemically inert, fire-resistant, and commercially available. The hollow portion of the first elongated member 203 can be sealed at both ends of the tube, thereby substantially stagnating the gas inside. Alternatively, the hollow portion can be used as a secondary pneumatic connection, such as a pressure sample line that transmits pressure feedback from the patient-side end of the tube to a controller. The first elongated member 203 can be optionally perforated. For example, the surface of the first elongated member 203 can be perforated on the side facing outward opposite to the lumen 207. In another embodiment, the hollow portion of the first elongated member 203 is filled with a liquid. Examples of liquids include water or other biocompatible liquids with high heat capacity. For example, nanofluids can be used. Examples of nanofluids with suitable heat capacity include water and nanoparticles of a substance such as aluminum.

[0032] The second elongated member 205 is also wound in a helical manner and joined to the first elongated member 203 between adjacent windings of the first elongated member 203. The second elongated member 205 forms at least a portion of the lumen 207 of the elongated tube. The second elongated member 205 acts as a structural support for the first elongated member 203.

[0033] In at least one embodiment, the second elongated member 205 is wider at the base (adjacent to the lumen 207) and narrower at the top. For example, the shape of the second elongated member can be approximately triangular, approximately T-shaped, or approximately Y-shaped. However, any shape that matches the contour of the corresponding first elongated member 203 is preferred.

[0034] Preferably, the second elongated member 205 is flexible to facilitate bending of the tube. Preferably, the second elongated member 205 is less flexible than the first elongated member 203. This improves the ability of the second elongated member 205 to structurally support the first elongated member 203. For example, the modulus of elasticity of the second elongated member 205 is preferably 30 MPa to 50 MPa (or about 30 MPa to 50 MPa). The modulus of elasticity of the first elongated member 203 is lower than that of the second elongated member 205. The second elongated member 205 can be solid or generally solid. Furthermore, the second elongated member 205 can enclose or house conductive material such as a filament, particularly a heating filament or a sensor (not shown). A heating filament can minimize the low-temperature surface where condensation from humid air may occur. It is also possible to use a heating filament to change the temperature profile of the gas in the lumen 207 of the composite tube 201. Various polymers and plastics, including medical-grade plastics, are suitable for the body of the second elongated member 205. Examples of suitable materials include polyolefin elastomers, polyether block amides, thermoplastic copolyester elastomers, EPDM-polypropylene mixtures, and thermoplastic polyurethanes. In some embodiments, the first elongated member 203 and the second elongated member 205 can be made from the same material. The second elongated member 205 can also be made from a material of a different color than the first elongated member 203, and the second elongated member 205 can be transparent, translucent, or opaque. For example, in one embodiment, the first elongated member 203 can be made from transparent plastic, and the second elongated member 205 can be made from opaque blue (or other color) plastic.

[0035] This helical-wound structure, comprising a flexible hollow body and an integrated support, can provide shatter resistance while remaining flexible enough to allow short-radius bending without kinking, blockage, or crushing of the tube wall. Preferably, the tube can be bent around a 25 mm diameter metal cylinder without kinking, blockage, or crushing, as defined in the test for increased flow resistance due to bending according to ISO 5367:2000(E). This structure can also provide a smooth inner lumen (tube bore), which helps keep the tube free of deposits and facilitates gas flow. The hollow body has been found to improve the thermal insulation properties of the tube while keeping the tube lightweight.

[0036] As described above, the composite tube 201 can be used as an expiratory tube and / or an inspiratory tube in a breathing circuit, or as part of a breathing circuit. Preferably, the composite tube 201 is used as at least an inspiratory tube.

[0037] Figure 2B shows a longitudinal section of the top of the composite tube 201 as an example of Figure 2A. Figure 2B has the same orientation as Figure 2A. This example further illustrates the hollow shape of the first elongated member 203. As can be seen in this example, the first elongated member 203 forms a plurality of hollow hemispherical bodies in longitudinal section. Several portions 209 of the first elongated member 203 overlap the adjacent winding portion of the second elongated member 205. A portion 211 of the first elongated member 203 forms the wall of the lumen (tube bore).

[0038] It has been found that the presence of gaps 213 between adjacent windings of the first elongated member 203, i.e., between adjacent hemispherical bodies, surprisingly improves the overall thermal insulation properties of the composite tube 201. Therefore, in some embodiments, adjacent hemispherical bodies are separated by gaps 213. Furthermore, some embodiments include the realization that providing gaps 213 between adjacent hemispherical bodies increases the thermal resistance (R value) and therefore decreases the thermal conductivity of the composite tube 201. This gap structure has also been found to improve the flexibility of the composite tube 201 by allowing bending at a shorter radius. A T-shaped second elongated member 205, as shown in Figure 2B, can help maintain gaps 213 between adjacent hemispherical bodies. Nevertheless, in some embodiments, adjacent hemispherical bodies are in contact. For example, adjacent hemispherical bodies can be joined together.

[0039] One or more conductive materials can be placed within the second elongated member 205 to heat or detect the gas flow. In this example, two heating filaments 215 are enclosed within the second elongated member 205, one on each side of the vertical portion of the "T". The heating filaments 215 include conductive materials such as an aluminum (Al) and / or copper (Cu) alloy or a conductive polymer. Preferably, the material forming the second elongated member 205 is selected so as to be nonreactive with the metal within the heating filaments 215 when the heating filaments 215 reach their operating temperature. The filaments 215 can be spaced away from the lumen 207 so as not to be exposed to the lumen 207. At one end of the composite tube, a pair of filaments can be made into a connecting loop.

[0040] In at least one embodiment, a plurality of filaments are arranged within the second elongated member 205. The filaments can be electrically aligned and connected to share a common rail. For example, a first filament, such as a heating filament, can be arranged on a first side of the second elongated member 205. A second filament, such as a sensing filament, can be arranged on a second side of the second elongated member 205. A third filament, such as a grounding filament, can be arranged between the first and second filaments. The first filament, the second filament, and / or the third filament can be aligned and connected at one end of the second elongated member 205.

[0041] Figure 2C shows a longitudinal section of the hemispherical body in Figure 2B. As shown, the portion 209 of the first elongated member 203 that overlaps the adjacent winding portion of the second elongated member 205 is characterized by the degree of the bonding region 217. The wider the bonding region, the greater the resistance of the tube to delamination at the contact surface between the first and second elongated members. Furthermore, or alternatively, the shape of the bead and / or hemispherical body can be adapted to increase the bonding region 217. For example, Figure 2D shows a relatively small bonding region on the left side. Figure 9B also demonstrates a relatively small bonding region. In contrast, Figure 2E has a much wider bonding region than that shown in Figure 2D due to the size and shape of the bead. Figures 9A and 9C also show relatively wide bonding regions. Each of these figures will be discussed in more detail later. While the configurations in Figures 2E, 9A, and 9C may be preferred in some embodiments, other configurations, including those in Figures 2D, 9B, and other variations, can be used in other embodiments as needed.

[0042] Figure 2D shows a longitudinal section of the top of another composite tube. Figure 2D has the same orientation as Figure 2B. This example further illustrates the hollow shape of the first elongated member 203 and demonstrates how the first elongated member 203 forms multiple hollow hemispherical bodies in longitudinal section. In this example, the hemispherical bodies are completely separated from each other by gaps 213. A roughly triangular second elongated member 205 supports the first elongated member 203.

[0043] Figure 2E shows a longitudinal section of the top of another composite tube. Figure 2E has the same orientation as Figure 2B. In the example of Figure 2E, the heating filaments 215 are spaced further apart from each other than the filaments 215 in Figure 2B. It has been found that increasing the space between the heating filaments can improve heating efficiency, and some embodiments include this implementation. Heating efficiency refers to the ratio of the amount of heat input to the tube to the amount of energy output from or recoverable from the tube. Generally, the more energy (or heat) dissipated from the tube, the lower the heating efficiency. To improve heating performance, the heating filaments 215 can be spaced equally (or nearly equally) along the bore of the tube. Alternatively, the filaments 215 can be placed at the ends of the second elongated member 205, thereby simplifying manufacturing.

[0044] Next, we refer to Figures 3A to 3G, which illustrate examples of configurations for the second elongated member 205. Figure 3A shows a cross-section of the second elongated member 205 having a shape similar to the T-shape shown in Figure 2B. In this exemplary embodiment, the second elongated member 205 does not have a heating filament. Other shapes for the second elongated member 205, including variations of the T-shape and triangular shapes as described later, can also be used.

[0045] Figure 3B shows a second elongated member 205 as another example having a T-shaped cross-section. In this example, the heated filaments 215 are embedded in slits 301 on each side of the vertical portion of the "T" of the second elongated member 205. In some embodiments, the slits 301 can be formed in the second elongated member 205 during extrusion. Alternatively, the slits 301 can be formed in the second elongated member 205 after extrusion. For example, a cutting tool can form the slits in the second elongated member 205. Preferably, the slits are formed by the heated filaments 215 immediately after extrusion, while the second elongated member 205 is relatively soft, as the heated filaments 215 are pushed or retracted (mechanically fixed) into the second elongated member 205. Alternatively, one or more heated filaments can be attached to the base of the elongated member so as to be exposed in the lumen of the tube (e.g., glued, bonded or partially embedded). In these embodiments, it may be desirable to insulate the filament to reduce the risk of combustion when a flammable gas such as oxygen is passed through the lumen of the tube.

[0046] Figure 3C shows a cross-section of a second elongated member 205 as yet another example. The second elongated member 205 has a roughly triangular shape. In this example, the heating filaments 215 are embedded on both sides of the triangle.

[0047] Figure 3D shows a cross-section of a second elongated member 205 as yet another example. The second elongated member 205 has four grooves 303. The grooves 303 are indentations or elongated furrows in the cross-sectional contour. In some embodiments, the grooves 303 can facilitate the formation of slits (not shown) for embedding filaments (not shown). In some embodiments, the grooves 303 facilitate the positioning of filaments (not shown) that are pushed or pulled into the second elongated member 205 and thereby embedded. In this example, the four starting grooves 303 facilitate the arrangement of up to four filaments, for example, four heating filaments, four sensing filaments, two heating filaments and two sensing filaments, three heating filaments and one sensing filament, or one heating filament and three sensing filaments. In some embodiments, the heating filaments can be positioned on the outside of the second elongated member 205. The sensing filaments can be positioned on the inside.

[0048] Figure 3E shows a cross-section of a second elongated member 205 as yet another example. The second elongated member 205 has a T-shaped contour and multiple grooves 303 for arranging heating filaments.

[0049] Figure 3F shows a cross-section of a second elongated member 205 as yet another example. Four filaments 215 are embedded, two on each side of the vertical "T" portion of the second elongated member 205. The filaments are embedded in the second elongated member 205 because it is extruded around the filaments, as will be described in more detail later. No slits are formed for embedding the heating filaments 215. In this example, the second elongated member 205 also has several grooves 303. Since the heating filaments 215 are embedded in the second elongated member 205, the grooves 303 are not used to facilitate the formation of slits for embedding the heating filaments. In this example, the grooves 303 can facilitate the separation of the embedded heating filaments, thereby facilitating the peeling of individual cores, for example, when terminating the heating filaments.

[0050] Figure 3G shows a cross-section of a second elongated member 205 as yet another example. The second elongated member 205 has a roughly triangular shape. In this example, the shape of the second elongated member 205 is similar to that of Figure 3C, but four filaments 215 are embedded in the second elongated member 205, all of which are centered in the bottom third of the second elongated member 205 and arranged along a roughly horizontal axis.

[0051] As explained above, it is sometimes desirable to increase the distance between filaments to improve heating efficiency. However, in some embodiments, when the heating filament 215 is incorporated into the composite tube 201, the filament 215 can be positioned relatively centrally within the second elongated member 205. Centralization promotes the robustness of the composite tube for reuse, partly because its position reduces the possibility of filament breakage when the composite tube 201 is repeatedly bent. By centralizing the filament 215, the risk of ignition can also be reduced because the filament 215 is covered with an insulating layer and separated from the gas flow path.

[0052] As described above, some of the examples illustrate preferred arrangements of the filaments 215 in the second elongated member 205. In the above examples, which have two or more filaments 215, the filaments 215 are generally aligned along the horizontal axis. Alternative configurations are also preferred. For example, two filaments can be aligned along the vertical axis or along the diagonal axis. Four filaments can be aligned along the vertical axis or the diagonal axis. Four filaments can be aligned in a cross configuration, with one filament positioned at the top of the second elongated member, one filament at the bottom of the second elongated member (near the lumen of the tube), and two filaments positioned on the opposing arms of the base of a "T", "Y", or triangle.

[0053] Tables 1A and 1B show some preferred dimensions of the medical tubing described herein, along with some preferred ranges for these dimensions. Dimensions refer to the cross-section of the tubing. In these tables, lumen diameter represents the inner diameter of the tubing. Pitch represents the distance between two repeating points measured axially along the tubing, i.e., the distance between the tips of adjacent vertical portions of the "T" of the second elongated member. Hemispherical width represents the width (maximum outer diameter) of the hemispherical body. Hemispherical height represents the height of the hemispherical body from the lumen of the tubing. Bead height represents the maximum height of the second elongated member from the lumen of the tubing (e.g., the height of the vertical portion of the "T"). Bead width represents the maximum width of the second elongated member (e.g., the width of the horizontal portion of the "T"). Hemispherical thickness represents the thickness of the hemispherical wall.

[0054] [Table 1]

[0055] [Table 2]

[0056] Tables 2A and 2B provide example ratios between the dimensions of tube features for the tubes listed in Tables 1A and 1B, respectively.

[0057] [Table 3]

[0058] [Table 4]

[0059] The following table shows some characteristic examples of the composite tubes described herein ("A") in which a heating filament is incorporated inside a second elongated member. For comparison, the characteristics of the Fisher & Paykel Model RT100 disposable corrugated tube ("B") in which the heating filament is helically wound inside the bore of the tube are also presented.

[0060] Flow resistance (RTF) was measured according to Annex A of ISO 5367:2000(E). The results are summarized in Table 3. As shown below, the RTF of the composite tube is lower than that of the Model RT100 tube.

[0061] [Table 5]

[0062] Condensate in the tube, or "rainout," refers to the weight of condensate collected per day at a gas flow rate of 20 L / min and room temperature of 18°C. Humidified air was continuously flowed through the tube from the chamber. The weight of the tube was recorded before and after each day of testing. These continuous tests were performed with the tube dried between each test. The results are shown in Table 4 below. The results show that the composite tube has significantly lower rainout than the Model RT100 tube.

[0063] [Table 6]

[0064] The power requirements refer to the power consumed during the condensate test. In this test, the ambient air was maintained at 18°C. The humidification chamber (see, for example, humidification chamber 129 in Figure 1) was powered by an MR850 heater base. The heating filament in the tube was powered independently from a DC power supply. Various flow rates were set to settle the chamber at 37°C at the chamber output. The DC voltage to the circuit was then varied to bring the temperature to 40°C at the circuit output. The voltage required to maintain the output temperature was recorded, and the resulting power was calculated. The results are shown in Table 5. The results show that composite tube A uses significantly more power than tube B. This is because tube B uses a helical heating filament inside the tube bore to heat the gas from 37°C to 40°C. The composite tube does not tend to heat the gas as quickly because the heating filament is located in the tube wall (embedded in the second elongated member). Instead, the composite tube prevents rainout by maintaining the gas temperature and keeping the tube bore at a temperature above the dew point of the humidifying gas.

[0065] [Table 7]

[0066] Tube flexibility was tested using a three-point bending test. The tubes were placed in a three-point bending test fixture and used with an Instron 5560 Test System to measure load and elongation. Each tube sample was tested three times, and the elongation of the tube under the applied load was measured to obtain the average stiffness constant. The average stiffness constants from Tables A and B are reproduced in Table 6.

[0067] [Table 8]

[0068] Manufacturing method Next, refer to Figures 4A to 4F, which demonstrate an exemplary method for manufacturing composite tubes.

[0069] Referring first to Figure 4A, in at least one embodiment, a method for manufacturing a composite tube includes the steps of providing a second elongated member 205 and winding the second elongated member 205 helically around a mandrel 401 such that the opposing side edges 403 of the second elongated member 205 are spaced apart in adjacent winding portions, thereby forming a second elongated member helix 405. In some embodiments, the second elongated member 205 can be wound directly around the mandrel. In other embodiments, a sacrificial layer can be provided on top of the mandrel.

[0070] In at least one embodiment, the method further includes the step of forming a second elongated member 205. Extrusion is a preferred method for forming the second elongated member 205. A second extruder can be configured to extrude the second elongated member 205 at a specified bead height. Thus, in at least one embodiment, the method includes the step of extruding the second elongated member 205.

[0071] As shown in Figure 4B, extrusion molding may be advantageous because the heated filaments 215 can be encapsulated within the second elongated member 205 when the second elongated member 205 is formed using, for example, an extruder having a crosshead extrusion die. Therefore, in some embodiments, the method includes the steps of providing one or more heated filaments 215 and forming the second elongated member 205 by encapsulating the heated filaments 215. The method may also include the step of providing the second elongated member 205 in which one or more heated filaments 215 are embedded or encapsulated.

[0072] In at least one embodiment, the method includes the step of embedding one or more filaments 215 into the second elongated member 205. For example, as shown in Figure 4C, the filaments 215 can be pushed (pulled in or mechanically positioned) to a predetermined depth within the second elongated member 205. Alternatively, a cut can be made in the second elongated member 205 to a specified depth, and the filaments 215 can be positioned in the cut. Preferably, the second elongated member 205 is extruded and pressed or cut immediately after the second elongated member 205 is soft.

[0073] As shown in Figures 4D and 4E, in at least one embodiment, the method comprises the steps of providing a first elongated member 203 and winding the first elongated member 203 helically around a second elongated member helix 405 such that some portions of the first elongated member 203 overlap adjacent windings of the second elongated member helix 405 and some portions of the first elongated member 203 are positioned adjacent to the mandrel 401 in the space between the windings of the second elongated member helix 405, thereby forming the first elongated member helix 407. Figure 4D shows an exemplary method in which the heating filament 215 is enclosed within the second elongated member 205 before the second elongated member helix is ​​formed. Figure 4E shows an exemplary method in which the heating filament 215 is embedded within the second elongated member 205 as the second elongated member helix is ​​formed. Another method for incorporating the filament 215 into the composite tube includes the step of encapsulating one or more filaments 215 between the first elongated member 203 and the second elongated member 205 in the region where the first elongated member 203 overlaps with the second elongated member 205.

[0074] The above-described alternative configurations, in which one or more heating filaments 215 are incorporated within the composite tube, have advantages over alternative configurations where the heating filaments are in the gas flow path. By placing the heating filaments 215 outside the gas flow path, performance is improved because the filaments heat the tube wall where condensation is most likely to occur. This configuration reduces the risk of combustion in a high-oxygen environment by moving the heating filaments outside the gas flow path. This feature also degrades performance by reducing the effectiveness of the heating wire when heating the gas passing through the tube. Nevertheless, in some embodiments, the composite tube 201 comprises one or more heating filaments 215 placed within the gas flow path. For example, the heating filaments can be installed in the lumen wall (tube bore), for example, in a helical configuration. An exemplary method for arranging one or more heating filaments 215 in the lumen wall includes the step of bonding, embedding, or otherwise forming the heating filaments on the surface of a second elongated member 205 that, when assembled, forms the lumen wall. Thus, in some embodiments, the method includes the step of arranging one or more heating filaments 215 in the lumen wall.

[0075] Whether the heating filament 215 is embedded in or enclosed in the second elongated member 205, or positioned on the second elongated member 205, or otherwise positioned inside or on the tube, in at least one embodiment, a circuit can be formed by connecting a pair of filaments into a connecting loop at one end of the composite tube.

[0076] Figure 4F shows a longitudinal section of the assembly shown in Figure 4E, focusing on the top of the mandrel 401 and the tops of the first elongated helix 407 and the second elongated helix 405. This example shows the second elongated helix 405 having a T-shaped second elongated member 205. When the second elongated member is formed, the heating filament 215 is embedded in the second elongated member 205. The right side of Figure 4F shows the hemispherical shape contour of the first elongated helix, as described above.

[0077] The method may also include the step of forming the first elongated member 203. Extrusion is a suitable method for forming the first elongated member 203. Therefore, in at least one embodiment, the method includes the step of extruding the first elongated member 203. The first elongated member 203 can also be manufactured by extruding two or more parts and joining them to form a single piece. In another alternative embodiment, the first elongated member 203 can also be manufactured by extruding cross-sections that are formed adjacently in a helical tube forming process or that create a hollow shape when joined together.

[0078] The present invention may also include the step of supplying a gas to the end of the first elongated member 203 at a pressure higher than atmospheric pressure. The gas may be, for example, air. Other gases may also be used as described above. Supplying a gas to the end of the first elongated member 203 can help maintain the open hollow shape as the first elongated member 203 is wound around the mandrel 401. The gas may be supplied before the first elongated member 203 is wound around the mandrel 401, while the first elongated member 203 is wound around the mandrel 401, or after the first elongated member 203 is wound around the mandrel 401. For example, an extruder with an extruder head / tip combination may supply or inject air into the hollow cavity of the first elongated member 203 as the first elongated member 203 is extruded. Therefore, in at least one embodiment, the method includes the steps of extruding a first elongated member 203 and supplying gas to the end of the first elongated member 203 at a pressure higher than atmospheric pressure after extrusion. It was found that a pressure of 15 cmH2O to 30 cmH2O (or about 15 cmH2O to 30 cmH2O) is preferable.

[0079] In at least one embodiment, the first elongated member 203 and the second elongated member 205 are helically wound around the mandrel 401. For example, the first elongated member 203 and the second elongated member 205 can be removed from the extrusion die at a high temperature of 200°C (or about 200°C) or higher, and then, after a short distance, applied to the mandrel. Preferably, the mandrel is cooled to a temperature of 20°C (or about 20°C) or lower, for example, approaching 0°C (or about 0°C), using a water jacket, a cooling device, and / or other suitable cooling method. After five (or about five) helical windings, the first elongated member 203 and the second elongated member 205 are further cooled with a cooling fluid (liquid or gas). In one embodiment, the cooling fluid is air released from a ring with jets surrounding the mandrel. After the components have been cooled and removed from the mandrel, a composite tube is formed having a lumen extending along the longitudinal axis and a hollow space surrounding the lumen. In this embodiment, no adhesive or other attachment mechanism is required to connect the first and second elongated members. In other embodiments, adhesive or other attachment mechanisms may be used to join or otherwise connect the two members. In another embodiment, the second elongated member 205 may be cooled after the extrusion and placement of the heated filament to freeze the position of the heated filament. Then, to strengthen the bond, the second elongated member 205 may be reheated when it is applied to the mandrel. Exemplary methods of reheating include using a spot heater, a heating roller, etc.

[0080] The method may also include a pair of heating or sensing filaments formed at one end of the composite tube, which form a connecting loop. For example, the ends of two heating or sensing filaments can be freed from the second elongated member 205 and then formed into a connecting loop by, for example, tying, joining, bonding, or fusing the two filaments together. Alternatively, the ends of the heating filaments can be left free from the second elongated member 205 during the manufacturing process and then formed into a connecting loop when the composite tube is assembled.

[0081] Medical tubing and manufacturing method using a single helical wound tube. Next, refer to Figures 5A to 5F. They show cross-sections of a tube comprising a single tubular element having a first elongated member or portion 203 and a second elongated member or portion 205. As shown, the second elongated portion 205 is integrated with the first elongated portion 203 and extends along the entire length of the single tubular element. In the illustrated embodiment, the single tubular element is an elongated hollow body which, in cross-section, has a relatively thin wall that partially defines a hollow portion 501, and on both sides of the elongated hollow body adjacent to the relatively thin wall, there are two reinforcing portions 205 that are relatively thicker or relatively stiffer. These reinforcing portions form part of the inner wall of the lumen 207 after the elongated hollow body is helically wound, thereby these reinforcing portions are also helically arranged between adjacent windings of the elongated hollow body.

[0082] In at least one embodiment, the method includes the step of forming an elongated hollow body having a first elongated portion 203 and a reinforcing portion 205. Extrusion is a preferred method for forming the elongated hollow body. Preferred cross-sectional shapes for tubular elements are shown in Figures 5A to 5F.

[0083] As described above, elongated hollow bodies can be made into medical tubes, and the above considerations are incorporated by reference. For example, in at least one embodiment, a method for manufacturing a medical tube includes the step of spirally winding or wrapping an elongated hollow body around a mandrel. This can be done at a high temperature, so that the elongated hollow body is cooled after being spirally wound to join adjacent windings together. As shown in Figure 5B, the opposing side edges of the reinforcing portion 205 can be in contact with adjacent windings. In other embodiments, as shown in Figures 5D and 5E, the opposing side edges of the second elongated member 205 can overlap adjacent windings. Heating filaments 215 can be incorporated into the second elongated member as described above and as shown in Figures 5A to 5F. For example, heating filaments can be provided on both sides of the elongated hollow body as shown in Figures 5A to 5D. Alternatively, heating filaments can be provided on only one side of the elongated hollow body as shown in Figures 5E to 5F. In any of these embodiments, the presence of a detection filament can also be incorporated.

[0084] Medical circuits Next, we refer to Figure 6, which shows an example of a medical circuit according to at least one embodiment. The circuit comprises one or more tubes as described above, namely a composite tube for an inhalation tube 103 and / or an exhalation tube 117. The characteristics of the inhalation tube 103 and the exhalation tube 117 are the same as those of the tubes described above with respect to Figure 1. The inhalation tube 103 has an inlet 109 that communicates with a humidifier 115 and an outlet 113 through which humidified gas passes when supplied to the patient 101. The exhalation tube 117 also has an inlet 109 that receives humidified gas exhaled from the patient and an outlet 113. As described above with respect to Figure 1, the outlet 113 of the exhalation tube 117 can discharge the exhaled gas to the atmosphere, to a ventilator / blower unit 115, to an air scrubber / filter (not shown), or to any other suitable location.

[0085] As described above, the heating filament 601 can be placed inside the inhalation tube 103 and / or the exhalation tube 117 to reduce the risk of rainout inside the tube by maintaining the tube wall temperature at a temperature above the dew point temperature.

[0086] Components of an air supply system Laparoscopic surgery, also known as minimally invasive surgery (MIS) or keyhole surgery, is a state-of-the-art surgical technique in which abdominal surgery is performed through smaller designs (usually 0.5 cm to 1.5 cm) compared to the larger incisions required for conventional surgical procedures. Laparoscopic surgery includes surgery in the abdomen or pelvic cavity. During laparoscopic surgery with insufflation, it may be desirable for the insufflation gas (usually CO2) to be humidified before entering the abdominal cavity. This can help prevent the patient's internal organs from "drying out" and shorten the time required for recovery from surgery. The insufflation system generally includes a humidifier chamber that holds a certain amount of water inside. The humidifier generally includes a heater plate that heats the water to produce water vapor, which is then supplied to the incoming gas to humidify it. The gas is then transported from the humidifier along with the water vapor.

[0087] Next, we refer to Figure 7, which shows an air supply system 701 according to at least one embodiment. The air supply system 701 includes an air supply device 703 that generates an air supply gas flow at a temperature higher than that of the atmosphere for delivery into the abdomen or abdominal cavity of a patient 705. The gas enters a humidifier 707 which includes a heater base 709 and a humidifier chamber 711, the chamber 711 being in contact with the heater base 709 when in use, thereby the heater base 709 providing heat to the chamber 711. In the humidifier 707, the air supply gas passes through the chamber 711 and is humidified to an appropriate level of humidity.

[0088] System 701 includes a delivery conduit 713 connecting a humidifier chamber 711 to the abdominal cavity or surgical site of patient 705. The conduit 713 has a first end and a second end, the first end of which is connected to the outlet of the humidifier chamber 711 and receives humidified gas from the chamber 711. The second end of the conduit 713 is positioned within the surgical site or abdominal cavity of patient 705, and the humidified supply gas travels from the chamber 711 through the conduit 713 into the surgical site, supplying and expanding the surgical site or abdominal cavity. The system also includes a controller (not shown) that adjusts the amount of humidity supplied to the gas by controlling the power supplied to a heater base 709. The controller can also be used to monitor the water in the humidifier chamber 711. A smoke extraction system 715 exiting the patient 705's body cavity is shown.

[0089] The smoke exhaust system 715 can be used in conjunction with the air supply system 701 described above, or with other suitable air supply systems. The smoke exhaust system 715 comprises a discharge or exhaust rim 717, a discharge assembly 719, and a filter 721. The discharge rim 717 connects the filter 721 and the discharge assembly 719, which, when in use, is positioned within or adjacent to the surgical site or abdominal cavity of the patient 705. The discharge rim 717 is a self-supporting tube (i.e., the tube can support its own weight without collapsing) and has two ends, namely a surgical site end and an outlet end.

[0090] At least one embodiment includes the realization that humidified gas can be delivered to the surgical site of the patient 705 with minimal heat loss by using a composite tube as a conduit 713. This reduces the heat input required to compensate for heat loss, thereby favorably reducing the overall energy consumption in the air supply system.

[0091] Coaxial tube A coaxial breathing tube can also be equipped with a composite tube as described above. In a coaxial breathing tube, the first gas space is an inspiratory rim or an expiratory rim, and the second gas space is the other of the inspiratory rim or the expiratory rim. One gas passage is provided between the inlet and outlet of the inspiratory rim, and one gas passage is provided between the inlet and outlet of the expiratory rim. In one embodiment, the first gas space is the inspiratory rim and the second gas space is the expiratory rim. Alternatively, the first gas space can be the expiratory rim and the second gas space can be the inspiratory rim.

[0092] Next, we refer to Figure 7, which shows a coaxial tube 701 according to at least one embodiment. In this example, the coaxial tube 701 is located between the patient 701 and the ventilator 705. Exhaled and inhaled gases flow through either the inner tube 707 or the space 709 between the inner tube 707 and the outer tube 711, respectively. It will be understood that the outer tube 711 does not need to be precisely aligned with the inner tube 707. Rather, "coaxial" refers to the fact that one tube is located inside another.

[0093] For heat transfer reasons, the inner tube 707 can carry inhaled gas in the space 713 within it, while exhaled gas is carried in the space 709 between the inner tube 707 and the outer tube 711. This airflow configuration is indicated by arrows. However, the opposite configuration is also possible, where the outer tube 711 carries inhaled gas and the inner tube 707 carries exhaled gas.

[0094] In at least one embodiment, the inner tube 707 is formed from a corrugated tube such as a Fisher & Paykel model RT100 disposable tube. The outer tube 711 can be formed from a composite tube as described above.

[0095] The coaxial tube 701 may prevent the ventilator 705 from detecting leaks in the inner tube 707. Such leaks could short-circuit patient 701, meaning that patient 701 would not receive sufficient oxygen. Such short-circuits can be detected by placing a sensor at the patient-side end of the coaxial tube 701. This sensor can be placed at the patient-side connector 715. A short-circuit closer to the ventilator 705 would cause patient 701 to continue rebreathing the air volume near patient 701. This would increase the concentration of carbon dioxide in the inspiratory airflow space 713 near patient 701, which can be directly detected by a CO2 sensor. Such sensors could include any one of several sensors currently on the market. Alternatively, this rebreathing can be detected by monitoring the gas temperature at the patient-side connector 715, where a temperature increase above a certain level indicates that rebreathing is occurring.

[0096] In addition to the above, in order to reduce or eliminate the formation of condensation in either the inner tube 707 or the outer tube 711, and to maintain a substantially uniform temperature of the gas flow through the coaxial tube 701, a heater such as a resistance heater filament may be provided in either the inner tube 707 or the outer tube 711, placed in the gas space 709 or 713, or placed in the wall of the inner tube 707 or the outer tube 711 itself.

[0097] Thermal properties In embodiments of the composite tube 201 incorporating the heating filament 215, heat may be lost through the walls of the first elongated member 203, thereby resulting in uneven heating. As described above, one way to compensate for these heat losses is to provide an external heat source to the walls of the first elongated member 203, which helps to regulate the temperature and prevent heat loss. However, other methods for optimizing the thermal properties can also be used.

[0098] Next, referring to Figures 9A to 9C, they demonstrate configuration examples for improving the hemispherical height (i.e., the cross-sectional height of the first elongated member 203 measured from the surface facing the inner lumen to the surface forming the maximum outer diameter) to enhance thermal properties.

[0099] The dimensions of the hemispherical body can be selected to reduce heat loss from the composite tube 201. Generally, increasing the height of the hemispherical body increases the effective thermal resistance of the tube 201 because the greater the hemispherical body height, the more adiabatic air the first elongated member 203 can hold. However, it has been found that at a certain hemispherical body height, changes in air density lead to convection inside the tube 201, thereby increasing heat loss. Also, at a certain hemispherical body height, the surface area becomes large enough that heat loss through the surface outweighs the benefit of the increased hemispherical body height. Several embodiments include implementations of these.

[0100] The radius of curvature and curvature of a hemispherical object can be useful in determining the desired height of the hemispherical object. The curvature of an object is defined as the reciprocal of its radius of curvature. Therefore, the larger the radius of curvature of an object, the less curved it is. For example, a flat surface has an infinite radius of curvature and is therefore curvature of 0.

[0101] Figure 9A shows a longitudinal section of the top of the composite tube. Figure 9A shows an embodiment of the composite tube 201 having a large hemispherical body. In this example, the hemispherical body has a relatively small radius of curvature and therefore a large curvature. Also, the hemispherical body is approximately three to four times taller than the height of the second elongated member 205.

[0102] Figure 9B shows a longitudinal section of the top of another composite tube. Figure 9B shows an embodiment of the composite tube 201 in which the hemispherical body is flattened at the top. In this example, the hemispherical body has a very large radius of curvature but a small curvature. Also, the hemispherical body is approximately the same height as the second elongated member 205.

[0103] Figure 9C shows a longitudinal section of the top of another composite tube. Figure 9C shows an embodiment of a composite tube 201 in which the width of the hemispherical body is greater than the height of the hemispherical body. In this example, the radius of curvature and curvature of the hemispherical body are between those of Figures 9A and 9B, and the radius center of the upper portion of the hemispherical body is outside the hemispherical body (compared to Figure 9A). The inflection points on the left and right sides of the hemispherical body are approximately in the middle (in the height direction) of the hemisphere (in contrast to the lower portion of the hemisphere as in Figure 9A). Also, the height of the hemispherical body is approximately twice that of the second elongated member 205, and as a result, the height of the hemispherical body is between those of Figures 9A and 9B.

[0104] The configuration in Figure 9A resulted in the lowest heat loss from the tubes. The configuration in Figure 9B resulted in the highest heat loss from the tubes. The configuration in Figure 9C had heat loss between that of the configurations in Figure 9A and Figure 9B. However, the large outer surface area and convective heat transfer in the configuration in Figure 9A resulted in inefficient heating. Therefore, of the three hemispherical arrangements in Figures 9A to 9C, Figure 9C was judged to have the best overall thermal characteristics. When the same thermal energy was input to the three tubes, the configuration in Figure 9C allowed for the maximum heat rise along the length of the tubes. The hemispheres in Figure 9C are large enough to increase the adiabatic air volume, but not large enough to cause significant convective heat loss. The configuration in Figure 9B was judged to have the worst thermal characteristics, meaning that the temperature rise along the length of the tubes was the lowest with the configuration in Figure 9B. The configuration in Figure 9A had intermediate thermal characteristics, with a lower temperature rise than the configuration in Figure 9C.

[0105] While the configuration shown in Figure 9C may be preferred in some embodiments, other configurations, including those shown in Figures 9A, 9B, and other variations, may be used as needed in other embodiments.

[0106] Table 7 shows the height of the hemispherical body, the outer diameter of the tube, and the radius of curvature for the configurations shown in Figures 9A, 9B, and 9C, respectively.

[0107] [Table 9]

[0108] Table 7A shows the height, outer diameter, and radius of curvature of hemispherical bodies with further configurations as shown in Figures 11A, 11B, and 11C.

[0109] [Table 10]

[0110] It should be noted that, generally speaking, the smaller the radius of curvature, the more the tube can bend around itself without the hemispherical body collapsing or "kinking." For example, Figure 11D shows a tube bent beyond its radius of curvature (in particular, the tube in Figure 11A bent around a radius of curvature of 5.7 mm), which results in kinking in the wall of the hemispherical body. Kinking is generally undesirable because it can impair the appearance of the tube and impair its thermal properties.

[0111] Therefore, in some applications, configurations with improved bending properties (such as those shown in Figure 9A or Figure 9B) may be desirable despite a decrease in thermal efficiency. In some applications, tubes with an outer diameter of 25mm to 26mm (or approximately 25mm to approximately 25mm) have been found to provide an excellent balance between thermal efficiency, flexibility, and bending performance. While the configurations in Figures 9A and 9B may be preferred in some embodiments, other configurations, including those in Figures 11A to 11D and other variations, may be used in other embodiments as needed.

[0112] Next, referring to Figures 9C to 9F, they demonstrate examples of positioning of the heating element 215 with a similar hemispherical shape to improve thermal properties. The position of the heating element 215 can change the thermal properties within the composite tube 201.

[0113] Figure 9C shows a longitudinal section of the top of another composite tube. Figure 9C shows an embodiment of a composite tube 201 in which the heating element 215 is located at the center of the second elongated member 205. This example shows heating elements 215 that are close to each other but not close to the hemispherical wall.

[0114] Figure 9D shows a longitudinal section of the top of another composite tube. Figure 9D shows an embodiment of the composite tube 201 in which the heating element 215 is further spaced apart in the second elongated member 205 compared to Figure 9C. These heating elements are closer to the hemispherical wall, allowing for better thermal regulation within the composite tube 201.

[0115] Figure 9E shows a longitudinal section of the top of another composite tube. Figure 9E shows an embodiment of the composite tube 201 in which the heating elements 215 are arranged vertically spaced apart along the vertical axis of the second elongated member 205. In this example, the heating elements 215 are equally close to each hemispherical wall.

[0116] Figure 9F shows a longitudinal section of the top of another composite tube. Figure 9F shows an embodiment of the composite tube 201 in which the heating elements 215 are spaced apart at both ends of the second elongated member 205. The heating elements 215 are closer to the hemispherical wall, in particular, compared to Figures 9C to 9E.

[0117] Of the four filament configurations shown in Figures 9C to 9F, Figure 9F was determined to have the best thermal characteristics. All of these configurations exhibited similar heat loss from the tube due to their similar hemispherical shapes. However, given the same thermal energy input to the tube, the filament configuration in Figure 9F allowed for the maximum temperature rise along the length of the tube. The configuration in Figure 9D was determined to have the next best thermal characteristics, allowing for the next largest temperature rise along the length of the tube. The configuration in Figure 9C performed next best. The configuration in Figure 9E had the worst performance when the same amount of heat was input, exhibiting the smallest temperature rise along the length of the tube.

[0118] While the configuration shown in Figure 9F may be preferred in some embodiments, other configurations, including those shown in Figures 9C, 9D, 9E, and other variations, can be used in other embodiments as needed.

[0119] Next, Figures 10A to 10C illustrate examples of the lamination configuration of the first elongated member 203. In some embodiments, it has been found that thermal dispersion can be improved by laminating multiple hemispherical bodies. These embodiments may be more beneficial when using the internal heating filament 215. Figure 10A shows a longitudinal section of the top of another composite tube. Figure 10A shows a cross-section of a composite tube 201 with no laminations.

[0120] Figure 10B shows a longitudinal section of the top of another composite tube. Figure 10B shows a composite tube 201 as another example of stacked hemispherical bodies. In this example, two hemispherical bodies are stacked on top of each other to form a first elongated member 203. Compared to Figure 10A, the total hemispherical height is maintained, but the hemispherical pitch is half that of Figure 10A. Also, the embodiment in Figure 10B has a slightly reduced air volume. The stacking of hemispherical bodies reduces natural convection and heat transfer in the gaps 213 between the hemispherical bodies, lowering the overall thermal resistance. The heat channels are increased in the stacked hemispherical bodies, thereby allowing heat to dissipate more easily through the composite tube 201.

[0121] Figure 10C shows a longitudinal section of the top of another composite tube. Figure 10C shows another example of a composite tube 201 made of stacked hemispherical bodies. In this example, three hemispherical bodies are stacked on top of each other to form the first elongated member 203. Compared to Figure 10A, the total hemispherical body height is maintained, but the hemispherical body pitch is 1 / 3 of that in Figure 10A. Also, in the embodiment of Figure 10B, the air volume is slightly reduced. The stacking of hemispherical bodies reduces natural convection and heat transfer in the gaps 213 between the hemispherical bodies.

[0122] Cleaning In at least one embodiment, the material of the composite tube can be selected to be treated by various cleaning methods. In some embodiments, the composite tube 201 can be cleaned using high-level disinfection (about 20 washing cycles). During high-level disinfection, the composite tube 201 undergoes pasteurization at about 75°C for about 30 minutes. Next, the composite tube 201 is immersed in 2% glutaraldehyde for about 20 minutes. The composite tube 201 is removed from the glutaraldehyde and immersed in 6% hydrogen peroxide for about 30 minutes. Finally, the composite tube 201 is removed from the hydrogen peroxide and immersed in 0.55% orthophthalaldehyde (OPA) for about 10 minutes.

[0123] In another embodiment, the composite tube 201 can be cleaned using sterilization (approximately 20 cycles). First, the composite tube 201 is placed in autoclave steam at approximately 121°C for approximately 30 minutes. Next, the temperature of the autoclave steam is raised to approximately 134°C for approximately 3 minutes. After autoclaving, the composite tube 201 is surrounded by 100% ethylene oxide (ETO) gas. Finally, the composite tube 201 is removed from the ETO gas and immersed in approximately 2.5% glutaraldehyde for approximately 10 hours.

[0124] The composite tube 201 can be fabricated from a material that can withstand repeated washing processes. In some embodiments, part or all of the composite tube 201 can be fabricated from a styrene-ethylene-butene-styrene block thermoplastic elastomer, for example, Kraiburg TF6STE, but is not limited. In other embodiments, the composite tube 201 can be fabricated from hyptrel, urethane, or silicone, but is not limited.

[0125] The above description of the present invention includes preferred forms thereof. Modifications to these forms can be made without departing from the scope of the invention. To those skilled in the art, many variations of the configuration of the invention, as well as substantially different embodiments and uses, will be suggested without departing from the scope of the invention as defined in the appended claims. The disclosures and descriptions herein are illustrative only and are not intended to limit in any sense.

Claims

1. A composite tube for use in a medical circuit to deliver gas to or remove gas from a patient, comprising: a first elongate member having a hollow body wound in a helical manner to at least partially form an elongate tube having a longitudinal axis, a lumen extending along said longitudinal axis, and a hollow wall at least partially surrounding said lumen; a second elongate member that is helically wound and joined between adjacent turns of the first elongate member, the second elongate member forming at least a portion of the lumen of the elongate tube; Equipped with the second elongate member has a longitudinal cross-section that is wider adjacent the lumen and narrower at a radial distance from the lumen; Composite tube.

2. A composite tube as described in claim 1, wherein the first elongated member and the second elongated member provide a smooth inner cavity surface for the inner cavity.

3. The composite tube of claim 1, wherein the second elongated member is formed from a single material.

4. A composite tube as described in claim 1, wherein the second elongated member has an approximately triangular cross-section.

5. A composite tube as described in claim 1, wherein the second elongated member is less flexible than the first elongated member.

6. The composite tube of claim 1, wherein the first and second elongated members helically wound and joined to one another provide crush resistance while providing sufficient flexibility to permit short radius bending without kinking.

7. The composite tube of claim 1, wherein some portions of the first elongated member overlap adjacent winding portions of the second elongated member.

8. The composite tube of claim 1 , wherein the first elongated member is a tube.

9. 3. The composite tube of claim 1 or 2, wherein the first elongate member, in longitudinal cross section, defines a plurality of hemispheres having flat surfaces in the lumen.

10. 10. The composite tube of claim 9, wherein adjacent hemispheres are separated by a gap above the second elongated member.

11. The composite tube of claim 10, wherein the gap allows for a smaller bending radius.

12. 10. The composite tube of claim 9, wherein adjacent hemispheres are not directly connected to one another.

13. 10. The composite tube of claim 9, wherein said hemispheres have perforations.

14. The composite tube of claim 1 , wherein the second elongate member has a longitudinal cross-section that is generally triangular, T-shaped, or Y-shaped.

15. 2. The composite tube of claim 1, wherein the second elongated member is less flexible than the first elongated member, and the composite tube comprises one or more conductive filaments embedded or encapsulated in the second elongated member.

16. The composite tube of claim 15 , wherein the one or more conductive filaments comprise a heating filament.

17. 17. The composite tube of claim 15 or 16, wherein the one or more conductive filaments include a sensing filament.

18. The composite tube of claim 15, comprising a plurality of the conductive filaments.

19. The composite tube of claim 15, comprising four of the conductive filaments.

20. The composite tube of claim 18, wherein the pair of conductive filaments are connected in a loop at one end of the composite tube.

21. The composite tube of claim 15 , wherein the one or more filaments are spaced from a wall of the lumen.

22. 16. The composite tube of claim 15, wherein the second elongated member has a longitudinal cross-section that is generally triangular, T-shaped, or Y-shaped, and the one or more conductive filaments are embedded or encapsulated on both sides of the triangle, T, or Y of the second elongated member.

23. The composite tube of any one of claims 1-4, 6-16 and 18-22, wherein the composite tube is one or more of a medical circuit component, an inspiratory tube, an expiratory tube, a PAP component, an insufflation circuit component, an expiratory component, a surgical component.

24. The composite tube of claim 1, wherein the first elongated member is substantially optically transparent.

25. A method of manufacturing a composite tube for use in delivering or removing gas to or from a patient in a medical circuit, comprising the steps of: Providing a first elongate member having a hollow body and a second elongate member; helically winding the second elongated member around a mandrel such that opposing side edge portions of the second elongated member are spaced apart at adjacent wraps, thereby forming a second elongated member helix; helically winding the first elongated member around the second elongated member spiral such that portions of the first elongated member overlap adjacent turns of the second elongated member spiral and a portion of the first elongated member is disposed adjacent the mandrel within a gap between the turns of the second elongated member spiral, thereby forming a first elongated member spiral; Including, The method of claim 1, wherein the second elongate member has a longitudinal cross-section that is wider adjacent to a lumen of the composite tube and narrower at a radial distance from the lumen.

26. 26. The method of claim 25, including the step of supplying air at a pressure greater than atmospheric pressure to an end of the first elongated member.

27. 26. The method of claim 25, further comprising cooling the second elongate member spiral and the first elongate member spiral to form a composite tube having a lumen extending along a longitudinal axis and a hollow space surrounding the lumen.

28. 26. The method of claim 25, wherein forming the second elongate member comprises embedding or encapsulating a conductive filament in the second elongate member.

29. The method of claim 25 further comprising forming the second elongated member.

30. 30. The method of claim 29, wherein the step of forming the second elongated member comprises extruding the second elongated member with a second extruder.

31. The method of claim 30 , wherein the second extruder is configured to encapsulate one or more conductive filaments in the second elongated member.

32. 30. The method of claim 28, wherein the conductive filament is non-reactive with the second elongate member.

33. 30. The method of claim 28, wherein the conductive filaments comprise aluminum or copper.

34. 30. The method of claim 28, further comprising forming a pair of conductive filaments into a connecting loop at one end of the composite tube.

35. The method of claim 25 including forming the first elongated member.

36. 36. The method of claim 35, wherein the step of forming the first elongated member comprises extruding the first elongated member with a first extruder.

37. The method of claim 36, further comprising extruding the second elongated member in a second extruder, the first extruder being separate from the second extruder.

38. The method of claim 25, wherein the second elongated member is less flexible than the first elongated member.

39. A method according to any one of claims 25 to 37, wherein the first elongate member and the second elongate member provide a smooth lumen surface to the lumen.

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