MEDICAL TUBES AND ASSOCIATED MANUFACTURING METHODS

Abstract

MEDICAL TUBING AND METHODS OF MANUFACTURING THE SAME Medical tubing and methods of manufacturing medical tubing are provided. The tubing may be a composite structure consisting of two or more distinct component elements that are spirally wound to form an elongated tube. For example, one of the component elements may be a spirally wound elongated hollow body (203), and the other component element may be an elongated structural component (205), also spirally wound, between turns of the spirally wound hollow body. The tubing, however, need not be made of distinct component elements. For example, an elongated hollow body formed (e.g., extruded) from a single material may be spirally wound to form an elongated tube. The elongated hollow body itself may, in cross-section, have a thin-walled portion and a relatively thicker or more rigid reinforcing portion.The tubes can be incorporated into various medical circuits or can be implemented for other medical uses. Figure for abstract: Fig. 2A.

Description

Title of the invention: MEDICAL TUBES AND ASSOCIATED MANUFACTURING METHODS Technical field

[0001] The present disclosure relates generally to tubing suitable for medical use, and in particular to tubing for use in medical circuits that may be used to deliver gases to a patient and / or exhaust gases from a patient, such as positive airway pressure (PAP) systems, ventilators, anesthesia systems, ventilation systems, and insufflation systems. Prior art

[0002] In medical circuits, various components transport warmed and / or humidified gases to and from patients. For example, in some breathing circuits such as PAP or assisted ventilation circuits, gases inhaled by a patient are delivered from a heating-humidifier device via an inspiration tube. For example, tubes may deliver humidified gas (often CO2) into the abdominal cavity in insufflation circuits. This can help prevent "dehydration" of the patient's internal organs, and may decrease the amount of time required for recovery after surgery. Unheated tubing results in significant heat loss through ambient cooling.This cooling can lead to condensation, or the formation of unwanted "condensation liquid," along the length of the tubing carrying the warm, humidified air. There is still a need for tubing that insulates against heat loss and, for example, allows for improved temperature and / or humidity control in medical circuits. Statement of the invention

[0003] Medical tubing and methods of making medical tubing are disclosed herein in various embodiments. In some embodiments, the tubing may be a composite structure consisting of two or more distinct component elements that are spirally wound to form an elongated tube. For example, one of the component elements may be a spirally wound elongated hollow body, and the other component element may be an elongated structural component also spirally wound between turns of the spirally wound hollow body. In other embodiments, the tubing need not be made of distinct component elements. For example, an elongated hollow body formed (e.g., extruded) from a single material may be spirally wound to form an elongated tube. The elongated hollow body itself may, in cross-section, having a thin-walled portion and a relatively thicker or more rigid reinforcing portion. The tubes may be incorporated into various medical circuits or may be implemented for other medical uses.

[0004] In at least one embodiment, a composite tube may include a first elongate member comprising a hollow body spirally wound to at least partially form an elongate tube having a longitudinal axis, a lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen. A second elongate member may be spirally 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. The terms "first elongate member" and "second elongate member" do not necessarily indicate an order, e.g., the order in which the component members are assembled. As described herein, the first elongate member and the second elongate member may also be portions of a single tube-shaped member.

[0005] In various embodiments, the aforementioned constituent element exhibits one, some, or all of the following properties, as well as properties described elsewhere in this disclosure.

[0006] The first elongated member may be a tube. The first elongated member may form, in longitudinal section, a plurality of bubbles having a flattened surface at the lumen. Adjacent bubbles may be separated by a gap above the second elongated member, or may not be directly connected to each other. The bubbles may include perforations. The second elongated member may have a longitudinal section that is wider proximate to the lumen and narrower radially away from the lumen. More specifically, the second elongated member may have a longitudinal section that is generally triangular, generally T-shaped, or generally Y-shaped. One or more conductive filaments may be included or encapsulated within the second elongated member.The one or more conductive filaments may be heating filaments (or more specifically, resistance heating filaments) and / or sensing filaments. The tube may include pairs of conductive filaments, for example, two or four conductive filaments. Pairs of conductive filaments may be formed to provide a connecting loop at one end of the composite tube. The one or more conductive filaments may be spaced from the lumen wall. In at least one embodiment, the second elongate member may have a longitudinal section that is generally triangular, generally T-shaped, or generally Y-shaped, and one or more conductive filaments may be included or encapsulated within the second . elongated element on opposite sides of the triangle, T-shape, or Y-shape.

[0007] The aforementioned component according to any or all of the preceding embodiments may be incorporated into a component of a medical circuit, an inspiration tube, an expiration tube, a component of a PAP system, an insufflation circuit, a component of an exploration system, or a surgical component, among other applications.

[0008] A method of 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 providing a first elongate member comprising a hollow body and a second elongate member configured to provide structural support to the first elongate member. The second elongate member is spirally wound around a mandrel, with opposite side edges of the second elongate member being spaced apart on adjacent turns, thereby forming a spiral of the second elongate member.The first elongated member is spirally wrapped around the spiral of the second elongated member, such that portions of the first elongated member overlap adjacent turns of the spiral of the second elongated member, and a portion of the first elongated member is disposed adjacent the mandrel in the space between turns of the spiral of the second elongated member, thereby forming a first elongated member spiral.

[0009] In various embodiments, the foregoing method may include one, some, or all of the following features. The method may include supplying air, at a pressure greater than atmospheric pressure, to one end of the first elongate member. The method may include cooling the spiral of the second elongate member and the spiral of the first elongate member, thereby forming a composite tube having a lumen extending along a longitudinal axis and a hollow space surrounding the lumen. The method may include forming the first elongate member. The method may include extruding the first elongate member with a first extruder. The method may include forming the second elongate member. The method may include extruding the second elongate member with a second extruder. The second extruder may be configured to encapsulate one or more conductive filaments within the second elongate member.Forming the second elongated member may include including conductive filaments in the second elongated member. The conductive filaments may be non-reactive with the second elongated member. The conductive filaments may include aluminum or copper alloys or other conductive materials. The method may include forming pairs of conductive filaments to produce a connecting loop at one end of the composite tube. The first extruder may be separate from the second extruder. extruder.

[0010] A medical tube is also disclosed. In at least one embodiment, the tube comprises an elongated hollow body spirally wound to form an elongated tube having a longitudinal axis, a lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen, the elongated hollow body having, in cross-section, a wall defining at least a portion of the hollow body. The tube may further comprise a reinforcing portion extending along a length of the elongated hollow body spirally positioned between adjacent turns of the elongated hollow body, the reinforcing portion forming a portion of the lumen of the elongated tube. The reinforcing portion may be relatively thicker or more rigid than the wall of the elongated hollow body.

[0011] In various embodiments, the foregoing tube exhibits one, some, or all of the following properties, as well as properties described elsewhere in this disclosure. The reinforcing portion may be formed from the same piece of material as the elongate hollow body. The elongate hollow body, in cross-section, may include two reinforcing portions on opposite sides of the elongate hollow body, the spiral winding of the elongate hollow body joining adjacent reinforcing portions to one another such that opposite edges of the reinforcing portions touch on adjacent turns of the elongate hollow body. Opposite side edges of the reinforcing portions may overlap on adjacent turns of the elongate hollow body. The reinforcing portion may be formed from a separate piece of material from the elongate hollow body.The hollow body may form, in longitudinal section, a plurality of bubbles having a flattened surface at the lumen. The bubbles may include perforations. The medical tubing may also include one or more conductive filaments included or encapsulated within the reinforcing portion. The conductive filament may be a heating filament and / or a sensing filament. The medical tubing may include two conductive filaments, one conductive filament being included or encapsulated in each of the reinforcing portions. The medical tubing may include two conductive filaments positioned on only one side of the elongated hollow body. Pairs of conductive filaments may be formed to provide a connecting loop at one end of the elongated tube. The one or more filaments may be spaced from the wall of the lumen.

[0012] The aforementioned tube according to any or all of the preceding embodiments may be incorporated into a constituent element of a medical circuit, an inspiration tube, an expiration tube, a constituent element of a PAP system, an insufflation circuit, a constituent element of an exploration system, or a surgical constituent element, among other applications.

[0013] A method of manufacturing a medical tube is also disclosed. In at least one embodiment, the method includes spirally wrapping an elongated hollow body 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, the elongated hollow body including, in cross-section, a wall defining at least a portion of the hollow body and two reinforcing portions on opposite sides of the elongated body forming a portion of the wall of the lumen, the two reinforcing portions being relatively thicker or stiffer than the wall defining at least a portion of the hollow body. The method may further include joining adjacent reinforcing portions to one another such that opposite edges of the reinforcing portions touch on adjacent turns of the elongated hollow body.

[0014] In various embodiments, the foregoing method may include one, some, or all of the following properties, or any other properties described elsewhere in this disclosure. Joining adjacent reinforcing portions to one another may cause the edges of the reinforcing portions to overlap. The method may further include supplying air, at a pressure greater than atmospheric pressure, to one end of the elongated hollow body. The method may further include cooling the elongated hollow body to join the adjacent reinforcing portions to one another. The method may further include extruding the elongated hollow body. The method may further include including conductive filaments in the reinforcing portions. The method may further include forming pairs of conductive filaments to produce a connecting loop at one end of the elongated tube.

[0015] According to a particular embodiment, the invention provides a composite tube comprising a first elongate member comprising a hollow body spirally wound to at least partially form an elongate tube having a longitudinal axis, a lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen; and a second elongate member spirally 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. The first elongate member is preferably a tube, and preferably forms, in longitudinal section, a plurality of bubbles having a flattened surface at the lumen. Adjacent bubbles may be separated by a gap above the second elongate member, and / or may not be directly connected to each other. Preferably, the bubbles include perforations.The second elongate member preferably has a longitudinal section that is wider proximate the lumen and narrower radially away from the lumen. Preferably, the second elongate member has a longitudinal section that is generally triangular and may be generally T-shaped or T-shaped. of Y. The composite tube may include one or more conductive filaments included or encapsulated within the second elongate member, the one or more conductive filaments preferably including one or more heating filaments or sensing filaments. Preferably, two or four conductive filaments are included or encapsulated within the second elongate member. Preferably, pairs of conductive filaments are formed to provide a connecting loop at one end of the composite tube. Preferably, the second elongate member has a longitudinal section that is generally triangular, generally T-shaped, or generally Y-shaped, and said one or more conductive filaments are included or encapsulated within the second elongate member on opposite sides of the triangle, T-shape, or Y-shape. Preferably, said one or more filaments are spaced from the wall of the lumen.The invention further provides any of a medical circuit component, an inspiration tube, an expiration tube, a PAP system component, an insufflation circuit component, an exploration system component, or a surgical component comprising said composite tube.

[0016] According to another embodiment, the invention provides a method of manufacturing a composite tube comprising providing a first elongate member comprising a hollow body and a second elongate member configured to provide structural support to the first elongate member; spirally wrapping the second elongate member around a mandrel, with opposite side edges of the second elongate member being spaced apart on adjacent turns, thereby forming a second elongate member spiral; and spirally wrapping the first elongate member around the spiral of the second elongate member, such that portions of the first elongate member overlap adjacent turns of the spiral of the second elongate member, with a portion of the first elongate member being disposed adjacent to the mandrel in the space between turns of the spiral of the second elongate member, thereby forming a first elongate member spiral.Preferably, the method further comprises supplying air, at a pressure greater than atmospheric pressure, to one end of the first elongated member and / or cooling the spiral of the second elongated member and the spiral of the first elongated member to form a composite tube having a lumen extending along a longitudinal axis and a hollow space surrounding the lumen and / or forming the second elongated member. Forming the second elongated member preferably comprises extruding the second elongated member with a second extruder, the second extruder preferably being configured to encapsulate one or more conductive filaments in the second elongated member. Forming the second elongated member may comprise including conductive filaments in the second elongated member. The conductive filaments are preferably non-reactive with the . second elongated member and may comprise aluminum or copper. The method may further comprise forming pairs of conductive filaments to produce a connecting loop at one end of the composite tube and / or forming the first elongated member, which operation may comprise extruding the first elongated member with a first extruder. The first extruder is preferably separate from the second extruder.

[0017] According to another embodiment, the invention provides a medical tube comprising an elongate hollow body spirally wound to form an elongate tube having a longitudinal axis, a lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen, the elongate hollow body having, in cross-section, a wall defining at least a portion of the hollow body; and a reinforcing portion extending along a length of the elongate hollow body, positioned spirally between adjacent turns of the elongate hollow body, the reinforcing portion forming a portion of the lumen of the elongate tube, the reinforcing portion being relatively thicker or stiffer than the wall of the elongate hollow body. The reinforcing portion is preferably formed from the same piece of material as the elongate hollow body.Preferably, the elongate hollow body, in cross-section, comprises two reinforcing portions on opposite sides of the elongate hollow body, the spiral winding of the elongate hollow body joining adjacent reinforcing portions to each other such that opposite edges of the reinforcing portions touch on adjacent turns of the elongate hollow body. Preferably, opposite side edges of the reinforcing portions overlap on adjacent turns of the elongate hollow body. Preferably, the reinforcing portion is made of a separate piece of material from the elongate hollow body. Preferably, the hollow body forms, in longitudinal section, a plurality of bubbles having a flattened surface at the lumen. The bubbles may have perforations. Preferably, the medical tubing comprises one or more conductive filaments included or encapsulated within the reinforcing portion.The conductive element or elements may comprise a heating filament and / or a sensing filament. Preferably, the medical tubing comprises two conductive filaments, one conductive filament being included or encapsulated in each of the reinforcing portions. The medical tubing may comprise two conductive filaments positioned on only one side of the elongated hollow body. Pairs of conductive filaments may be formed to provide a connecting loop at one end of the elongated tube. One or more filaments are spaced from the wall of the lumen. The invention further provides any of a component of a medical circuit, an inspiration tube, an expiration tube, a component of a PAP system, a component of an insufflation circuit, a component . of an exploration system or a surgical component comprising said medical tube.

[0018] According to another embodiment, the invention provides a method of manufacturing a medical tube comprising spirally winding an elongate hollow body around a mandrel to form an elongate tube having a longitudinal axis, a lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen, the elongate hollow body having, in cross-section, a wall defining at least a portion of the hollow body and two reinforcing portions on opposite sides of the elongate body forming a portion of the wall of the lumen, the two reinforcing portions being relatively thicker or stiffer than the wall defining at least a portion of the hollow body; and joining adjacent reinforcing portions to one another such that opposite edges of the reinforcing portions touch on adjacent turns of the elongate hollow body.Joining adjacent reinforcing portions to each other may cause overlapping of the edges of the reinforcing portions. Preferably, the method further comprises supplying air, at a pressure greater than atmospheric pressure, to one end of the elongate hollow body and / or cooling the elongate hollow body to join the adjacent reinforcing portions to each other and / or extruding the elongate hollow body and / or including conductive filaments in the reinforcing portions and / or forming pairs of conductive filaments to produce a connecting loop at one end of the elongate tube.

[0019] For the purpose of summarizing the invention, certain aspects, advantages, and novel features of the invention have been described herein. It will be understood that it will not necessarily be possible to obtain all of these advantages with respect to any particular embodiment of the invention. Thus, the invention may be made or practiced in a manner that provides or optimizes one advantage or group of advantages taught herein, without necessarily providing other advantages that may be taught or suggested herein. Brief description of the drawings

[0020] Exemplary embodiments implementing the various features of the disclosed systems and methods are described below with reference to the drawings. The drawings and associated descriptions are presented to illustrate the embodiments and not to limit the scope of the disclosure.

[0021] [fig. 1] [fig.l] shows a schematic representation of a medical circuit integrating one or more medical tubes.

[0022] [fig.2A] [fig.2A] shows a side plan view of a section of an exemplary composite tube.

[0023] [fig.2B] [fig.2B] shows a longitudinal section of an upper portion of a tube similar to the composite tube example of [fig.2A].

[0024] [fig.2C] [fig.2C] shows another longitudinal section illustrating a first elongated element in the composite tube.

[0025] [fig.2D] [fig.2D] shows another longitudinal section of an upper part of a tube.

[0026] [fig.2E] [fig.2E] shows another longitudinal section of an upper part of a tube.

[0027] [fig.3A] [fig.3A] shows a cross-section of a second elongated element in the composite tube.

[0028] [fig.3B] [fig.3B] shows another cross-section of a second elongated element.

[0029] [fig.3C] [fig.3C] shows another example of a second elongated element.

[0030] [fig.3D] [fig.3D] shows another example of a second elongated element.

[0031] [fig.3E] [fig.3E] shows another example of a second elongated element.

[0032] [fig.3F] [fig.3F] shows another example of a second elongated element.

[0033] [fig.3G] [fig.3G] shows another example of a second elongated element.

[0034] [fig.4A] [fig.4A] shows one aspect of a method of forming the composite tube.

[0035] [fig.4B] [fig.4B] shows a second elongated element wound in a spiral.

[0036] [fig.4C] [fig.4C] shows another aspect of a tube forming method composite.

[0037] [fig.4D] [fig.4D] shows another aspect of a method of forming the composite tube.

[0038] [fig.4E] [fig.4E] shows another aspect of a method of forming the composite tube.

[0039] [fig.4F] [fig.4F] shows another aspect of a method of forming the composite tube.

[0040] [fig.5A] FIGS. 5A-5B show another example illustrating a single elongated hollow body being spirally wound to form a medical tube.

[0041] [fig.5B] FIGS. 5A-5B show another example illustrating a single elongated hollow body being spirally wound to form a medical tube.

[0042] [fig.5C] FIGS. 5C-5F show examples of other unique elongated hollow bodies being spirally wound to form medical tubing.

[0043] [fig.5D] FIGS. 5C-5F show examples of other unique elongated hollow bodies being spirally wound to form medical tubing.

[0044] [fig.5E] FIGS. 5C-5F show examples of other unique elongated hollow bodies being spirally wound to form medical tubing.

[0045] [fig.5F] FIGS. 5C-5F show examples of other elongated hollow bodies unique being spirally wound to form a medical tube.

[0046] [fig.6] [fig.6] shows an example of a medical circuit according to at least one rea lization.

[0047] [fig.7] [fig.7] shows an insufflation system according to at least one embodiment.

[0048] [fig.8] [fig.8] is a schematic representation of a coaxial tube, according to the least one achievement.

[0049] [fig.9A] FIGS. 9A-C show examples of first elongated member shapes configured to improve thermal efficiency.

[0050] [fig.9B] FIGS. 9A-C show examples of first elongated member shapes configured to improve thermal efficiency.

[0051] [fig.9C] FIGS. 9A-C show examples of first elongated member shapes configured to improve thermal efficiency.

[0052] [fig.9D] FIGS. 9D-F show examples of filament arrangements configured to improve thermal efficiency.

[0053] [fig.9E] FIGS. 9D-F show examples of filament arrangements configured to improve thermal efficiency.

[0054] [fig.9F] FIGS. 9D-F show examples of filament arrangements configured to improve thermal efficiency.

[0055] [fig.10A] FIGS. 10A-C show examples of superposition of the first elongated element.

[0056] [fig.lOB] FIGS. 10A-C show examples of superposition of the first elongated element.

[0057] [fig.10C] FIGS. 10A-C show examples of superposition of the first elongated element.

[0058] [fig.l IA] FIGS. 11A-D show properties relating to the radius of curvature of tubes according to various embodiments.

[0059] [fig.l IB] FIGS. 11A-D show properties relating to the radius of curvature of tubes according to various embodiments.

[0060] [fig.l IC] FIGS. 11A-D show properties relating to the radius of curvature of tubes according to various embodiments.

[0061] [fig.l 1D] FIGS. 11A-D show properties relating to the radius of curvature of tubes according to various embodiments.

[0062] Throughout the drawings, reference numerals are reused to indicate correspondence between elements bearing the reference numerals (or similar elements). In addition, the first digit of each reference numeral indicates the figure in which the element first appears. Description of the embodiments

[0063] Detailed information regarding several illustrative embodiments of the implementation of apparatuses and methods described herein are set forth below with reference to the figures. The invention is not limited to these described embodiments.

[0064] Breathing circuit comprising one or more medical tubes

[0065] For a more detailed understanding of the disclosure, reference is first made to [fig.l], which shows a breathing circuit according to at least one embodiment, which includes one or more medical tubes. The term "tube" is a general term and will be given the meaning that would ordinarily and customarily be given to it by those skilled in the art (i.e., it will not be limited to any particular or specially adapted meaning) and includes, without limitation, non-cylindrical passages. Some embodiments may incorporate a composite tube, which may generally be defined as a tube comprising two or more parts, or more specifically, in some embodiments, two or more component elements, as described in more detail below. This breathing circuit may be a continuous, variable, or bi-level positive airway pressure (PAP) system, or another form of respiratory therapy.

[0066] Gases may be transported in the circuit of [Fig. 1] as shown below. Dry gases pass from a blowing ventilator / ventilator device 105 to a humidifier 107, which humidifies the dry gases. The humidifier 107 is connected to the inlet 109 (the end for receiving the humidified gases) of the inspiration tube 103 via a port 111, thereby delivering the humidified gases to the inspiration tube 103. An inspiration tube is a tube that is configured to deliver respiratory gases to a patient, and may be made of a composite tube as described in more detail below. Gases flow through the inspiration tube 103 to the outlet 113 (the end intended to expel the humidified gases), then to the patient 101 via a patient interface 115 connected to the outlet 113.

[0067] An exhalation tube 117 is also connected to the patient interface 115. An exhalation tube is a tube that is configured to evacuate humidified gases exhaled by a patient. Here, the exhalation tube 117 returns the exhaled humidified gases from the patient interface 115 to the ventilation device / blower 105.

[0068] In this example, dry gases enter the ventilation / blower device 105 via an air intake 119. A fan 121 may enhance the flow of gas entering the ventilation / blower device by drawing air or other gases through the air intake 119. The fan 121 may be, for example, a variable speed fan, with an electronic controller 123 controlling the speed of the fan. In particular, the operation of the electronic controller 123 may be controlled by a central electronic controller 125 in response to inputs from the central controller 125, and to a value required predetermined (preset value) pressure or fan speed set by the user via a dial 127.

[0069] The humidifier 107 includes a humidification chamber 129 containing a volume of water 130 or other humidification liquid suitable for this purpose. Preferably, the humidification chamber 129 is removable from the humidifier 107 after use. The removability allows the humidification chamber 129 to be more easily sterilized or removed. However, the humidification chamber 129 as part of the humidifier 107 may be a single-piece structure. The body of the humidification chamber 129 may be composed of a non-conductive material such as glass or plastics. However, the humidification chamber 129 may also include conductive constituent elements. For example, the humidification chamber 129 may include a highly thermally conductive base (e.g., an aluminum base) in contact with or associated with a heating plate 131 on the humidifier 107.

[0070] The humidifier 107 may also include electronic controls. In this example, the humidifier 107 includes an electronic, analog, or digital central controller 125. Preferably, the central controller 125 is a microprocessor controller executing commands from software stored in an associated memory. In response to the user-set humidity or temperature value, entered via a user interface 133, for example, and other inputs, the central controller 125 determines when (or to what level) to operate the heating plate 131 to heat the water 130 within the humidification chamber 129.

[0071] Any patient interface 115 suitable for this purpose may be incorporated. The term "patient interface" is a general term and will be given the meaning ordinarily and customarily given to it by those skilled in the art (i.e., it will not be limited to a particular or specially adapted meaning) and includes, without limitation, masks (such as tracheal masks, face masks, and nasal masks), cannulas, and nasal pillow masks. A temperature probe 135 may be connected to the inspiration tube 103 near the patient interface 115, or to the patient interface 115. The temperature probe 135 monitors the temperature near or at the patient interface 115.A heating filament (not shown here) associated with the temperature probe may be used to adjust the temperature of the patient interface 115 and / or the inspiration tube 103, to raise the temperature of the inspiration tube 103 and / or the patient interface 115 to a level above the saturation temperature, thereby reducing the possibility of unwanted condensation.

[0072] In [Fig. 1], the exhaled humidified gases are returned from the patient interface 115 to the ventilation / blower device 105 via the exhalation tube 117. The tube exhalation tube 117 may also be a composite tube, as described in more detail below. However, exhalation tube 117 may also be a medical tube previously known in the art. In each case, exhalation tube 117 may be provided with a temperature probe and / or a heating filament, as described above with respect to inspiration tube 103, forming a single piece therewith to reduce the possibility of condensation. Furthermore, exhalation tube 117 need not return exhaled gases to ventilation device / blower 105. Instead, exhaled humidified gases may be sent directly to the ambient environment or to other ancillary equipment, such as an air scrubber / filter (not shown here). In some embodiments, the exhalation tube is omitted entirely.

[0073] Composite tubes

[0074] [Fig. 2A] shows a side plan view of a section of an exemplary composite tube 201. In general, the composite tube 201 includes a first elongated member 203 and a second elongated member 205. The term "member" is a general term and will be given the meaning ordinarily and customarily assigned to those skilled in the art (i.e., it will not be limited to any particular or specially adapted meaning) and includes, without limitation, integral parts, integrated constituent elements, and separate constituent elements. Thus, although [Fig. 2A] illustrates an embodiment consisting of two separate constituent elements, it will be noted that in other embodiments (such as those described in FIGS. 5A-5D below), the first elongated member 203 and the second elongated member 205 may also represent regions in a tube formed of a single material.Thus, the first elongated member 203 may represent a hollow portion of a tube, while the second elongated member 205 represents a structural support portion or a reinforcing portion of the tube, adding structural support to the hollow portion. The hollow portion and the structural support portion may have a spiral configuration, as described herein. The composite tube 201 may be used to form the inhalation tube 103 and / or the exhalation tube 117 as described above, a coaxial tube as described below, or any other tubes described elsewhere in this disclosure.

[0075] In this example, the first elongate member 203 comprises a hollow body spirally wound to form, at least in part, an elongate tube having a longitudinal axis LA—LA and a lumen 207 extending along the longitudinal axis LA—LA. In at least one embodiment, the first elongate member 203 is a tube. Preferably, the first elongate member 203 is flexible. Further, the first elongate member 203 is preferably transparent or, at least, semi-transparent or semi-opaque. A certain level of optical transparency allows a caregiver or user to inspect the light 207 to verify that it is not blocked or contains contaminants or to confirm the presence of moisture. Various plastic materials, including medical grade plastics, may be used for the body of the first elongated member 203. Examples of materials suitable for this purpose include polyolefin elastomers, amides having polyether blocks, thermoplastic copolyester elastomers, EPDM-polypropylene blends, and thermoplastic polyurethanes.

[0076] The hollow body structure of the first elongate member 203 contributes to the insulating properties of the composite tube 201. An insulating tube 201 is desirable because, as explained above, it prevents heat loss. This may allow the tube 201 to deliver gas from a heater-humidifier to a patient while maintaining the gas in its conditioned state with minimal energy consumption.

[0077] In at least one embodiment, the hollow portion of the first elongate member 203 is filled with a gas. The gas may be air, which is desirable due to its low thermal conductivity (2.62 x 10-2 W / mK at 300 K) and very low cost. A gas more viscous than air may also advantageously be used, since a higher viscosity reduces convection heat transfer. Thus, gases such as argon (17.72 x 10-3 W / mK at 300 K), krypton (9.43 x 10-3 W / mK at 300 K), and xenon (5.65 x 10-3 W / mK at 300 K) may improve insulation performance. Each of these gases is non-toxic, chemically inert, has flame retardant properties, and is commercially available. The hollow portion of the first elongate member 203 may be sealed at both ends of the tube, such that the gas therein is substantially stagnant.Alternatively, the hollow portion may be a secondary pneumatic connection, such as a pressure sampling hose for transmitting pressure feedback from the patient end of the tube to a controller. The first elongated member 203 may optionally be perforated. For example, the surface of the first elongated member 203 may be perforated on an outwardly facing surface opposite the lumen 207. In another embodiment, the hollow portion of the first elongated member 203 is filled with a liquid. Examples of liquids that may be used include water or other biocompatible liquids having a high heat capacity. For example, nanofluids may be used. Examples of nanofluids having adequate heat capacity include water and nanoparticles of substances such as aluminum.

[0078] The second elongate member 205 is also spirally wound and joined to the first elongate member 203 between adjacent turns of the first elongate member 203. The second elongate member 205 forms at least a portion of the lumen 207 of the tube. elongated. The second elongated element 205 acts as a structural support for the first elongated element 203.

[0079] In at least one embodiment, the second elongate member 205 is wider at the base (near the lumen 207) and narrower at the top. For example, the second elongate member may be generally triangular in shape, generally T-shaped, or generally Y-shaped. However, any shape following the contours of the corresponding first elongate member 203 may be used.

[0080] Preferably, the second elongated member 205 is flexible, to facilitate bending of the tube. It is desirable that the second elongated member 205 be less flexible than the first elongated member 203. This improves the ability of the second elongated member 205 to provide structural support to the first elongated member 203. For example, the modulus of the second elongated member 205 is preferably 30-50 MPa (or about 30-50 MPa). The modulus of the first elongated member 203 is less than the modulus of the second elongated member 205. The second elongated member 205 may be solid or substantially solid. In addition, the second elongated member 205 may contain encapsulated conductive material or house conductive material, such as filaments, and more specifically heating or sensing filaments (not shown here). The heating filaments may minimize cold surfaces on which condensate can form from moisture-laden air.The heating filaments may also be used to modify the gas temperature profile in the lumen 207 of the composite tube 201. Various polymers and plastics, including medical-grade plastics, may be used for the body of the second elongated member 205. Examples of materials suitable for this purpose include polyolefin elastomers, polyether block amides, thermoplastic copolyester elastomers, EPDM-polypropylene blends, and thermoplastic polyurethanes. In some embodiments, the first elongated member 203 and the second elongated member 205 may be made of the same material. The second elongated member 205 may also be made of a material that is a different color than the first elongated member 203, and may be transparent, translucent, or opaque.For example, in one embodiment, the first elongated member 203 may be made of a transparent plastic material, and the second elongated member 205 may be made of an opaque blue (or other color) plastic material.

[0081] This spirally wound structure comprising a flexible hollow body and an integral support can provide crush resistance, while leaving the tube wall sufficiently flexible to allow flexing over a small radius without causing kinking, obstruction or sagging. Preferably, the tube can be flexed around of a 25 mm diameter metal cylinder without kinks, obstructions, or sagging, as defined in the test for increased flexural flow resistance according to ISO 5367:2000(E). This structure can also produce a smooth lumen surface (tube bore), which helps keep the tube free of deposits and improves gas flow. The hollow body has been found to improve the insulating properties of a tube, while allowing the tube to remain lightweight.

[0082] As explained above, the composite tube 201 may be used as an exhalation tube and / or as an inspiration tube in a breathing circuit, or part of a breathing circuit. Preferably, the composite tube 201 is used at least as an inspiration tube.

[0083] [Fig.2B] shows a longitudinal section of an upper portion of the exemplary composite tube 201 of [Fig.2A]. [Fig.2B] has the same orientation as [Fig.2A]. This example further illustrates the hollow body shape of the first elongate member 203. As seen in this example, the first elongate member 203 forms, in longitudinal section, a plurality of hollow bubbles. Portions 209 of the first elongate member 203 overlap adjacent turns of the second elongate member 205. A portion 211 of the first elongate member 203 forms the wall of the lumen (tube bore).

[0084] It has been unexpectedly discovered that the presence of a gap 213 between adjacent turns of the first elongate member 203, i.e., between adjacent bubbles, improves the overall insulating properties of the composite tube 201. Thus, in some embodiments, adjacent bubbles are separated by a gap 213. Further, some embodiments incorporate the realization that the presence of a gap 213 between adjacent bubbles increases the heat transfer resistivity (the R-value) and, consequently, decreases the thermal conductivity of the composite tube 201. This configuration incorporating a gap has also been found to improve the flexibility of the composite tube 201 by allowing flexures over a smaller radius. A second T-shaped elongate member 205, as shown in [fig.2B], may help maintain a gap 213 between adjacent bubbles.However, in some embodiments, adjacent bubbles touch each other. For example, adjacent bubbles may be linked to each other.

[0085] One or more conductive materials may be disposed within the second elongate member 205 for heating or sensing gas flow. In this example, two heating filaments 215 are encapsulated within the second elongate member 205, one on each side of the vertical portion of the “T”. The heating filaments 215 comprise a conductive material, for example, aluminum (Al) and / or copper (Cu) alloys, or a conductive polymer. Preferably, the material forming the second elongate member 205 is selected to be non-reactive with metal present in the heating filaments 215 when the heating filaments 215 reach their operating temperature. The filaments 215 may be spaced from the lumen 207 so that the filaments are not exposed to the lumen 207. Pairs of filaments may be formed at one end of the composite tube to produce a connecting loop.

[0086] In at least one embodiment, a plurality of filaments are disposed within the second elongated member 205. The filaments may be electrically connected to each other to share a common rail. For example, a first filament, such as a heater filament, may be disposed on a first side of the second elongated member 205. A second filament, such as a sensing filament, may be disposed on a second side of the second elongated member 205. A third filament, such as a ground filament, may be disposed between the first filament and the second filament. The first, second, and / or third filaments may be connected to each other at one end of the second elongated member 205.

[0087] [Fig. 2C] shows a longitudinal section of the bubbles in [Fig. 2B]. As indicated, the portions 209 of the first elongate member 203 overlapping adjacent turns of the second elongate member 205 are characterized by a degree of anchoring region 217. A larger anchoring region improves the resistance of the tubes to delamination at the interface of the first elongate member and the second elongate member. Additionally or otherwise, the shape of the bead and / or bubble may be adapted to expand the anchoring region 217. For example, [Fig. 2D] shows a relatively small anchoring area on the left side. [Fig. 9B] also shows a smaller anchoring region. In contrast, [Fig. 2E] shows a much larger anchoring region than that shown in [Fig. 2D], due to the size and shape of the bead. FIGS. 9A and 9C also illustrate a more extensive anchoring region.Each of these figures is discussed in more detail below. It will be noted that although the configurations of FIGS. 2E, 9A, and 9C may be preferred in some embodiments, other configurations, including those of FIGS. 2D, 9B, and other variations, may be used as desired in other embodiments.

[0088] [Fig.2D] shows a longitudinal section of an upper portion of another composite tube. [Fig.2D] has the same orientation as [Fig.2B]. This example further illustrates the hollow body shape of the first elongate member 203 and shows how the first elongate member 203 forms, in longitudinal section, a plurality of hollow bubbles. In this example, the bubbles are completely separated from each other by a gap 213. A second, generally triangular elongate member 205 supports the first elongate member 203.

[0089] [Fig.2E] shows a longitudinal section of an upper part of another tube composite. [Fig. 2E] has the same orientation as [Fig. 2B]. In the example of [Fig. 2E], the heating filaments 215 are spaced further apart than the filaments 215 in [Fig. 2B]. It has been discovered that increasing the spacing between the heating filaments can improve thermal efficiency, and some implementations incorporate the recognition of this fact. Thermal efficiency refers to the ratio of the amount of heat introduced into the tube versus the amount of energy exiting the tube or recoverable from the tube. Generally speaking, the more energy (or heat) dissipated from the tube, the lower the thermal efficiency. To improve heating performance, the heating filaments 215 may be equidistant (or approximately equidistant) along the tube bore. Alternatively, the filaments 215 may be positioned at the ends of the second elongated member 205, which may facilitate manufacturing.

[0090] Reference is then made to FIGS. 3A-3G, which show exemplary configurations for the second elongate member 205. [Fig. 3A] shows a section of a second elongate member 205 having a shape similar to the T-shape illustrated in [Fig. 2B]. In this exemplary embodiment, the second elongate member 205 does not include heating filaments. Other shapes may also be used for the second elongate member 205, including variations of the T-shape as described below and triangular shapes.

[0091] [Fig. 3B] shows another example of a second elongate member 205 having a T-shaped cross-section. In this example, heating filaments 215 are included in cuts 301 formed in the second elongate member 205 on either side of the vertical portion of the "T". In some embodiments, the cuts 301 may be formed in the second elongate member 205 during extrusion. Alternatively, the cuts 301 may be formed in the second elongate member 205 after extrusion. For example, a cutting tool may form the cuts in the second elongate member 205. Preferably, the cuts are formed by the heating filaments 215 as they are pressed or pulled (mechanically secured) into the second elongate member 205 shortly after extrusion, while the second elongate member 205 is relatively soft.Alternatively, one or more heating filaments may be mounted (e.g., glued, bonded, or partially enclosed) on the base of the elongate member, such that the filament(s) are exposed to the tube lumen. In such embodiments, it may be desirable to enclose the filament(s) in insulation to reduce the risk of fire when a flammable gas such as oxygen flows into the tube lumen.

[0092] [Fig.3C] shows yet another example of a second elongate member 205 viewed in section. The second elongate member 205 has a generally triangular shape. In this example, heating filaments 215 are included on opposite sides of the triangle.

[0093] [Fig. 3D] shows yet another example of a second elongate member 205 viewed in section. The second elongate member 205 includes four grooves 303. The grooves 303 are indentations or furrows in the section profile. In some embodiments, the grooves 303 may facilitate the formation of cuts (not shown here) for the inclusion of filaments (not shown here). In some embodiments, the grooves 303 facilitate the positioning of filaments (not shown here), which are pressed or pulled into inclusion in the second elongate member 205. In this example, the four initiating grooves 303 facilitate the placement 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 may be located on the exterior of the second elongated member 205. The sensing filaments may be located on the interior.

[0094] [Fig.3E] shows yet another example of a second elongate element 205 seen in section. The second elongate element 205 has a T-shaped profile and comprises a plurality of grooves 303 for the placement of heating filaments.

[0095] [Fig. 3F] shows yet another example of a second elongate member 205 viewed in section. Four filaments 215 are encapsulated within the second elongate member 205, two on each side of the vertical portion of the "T". As explained in more detail below, the filaments are encapsulated within the second elongate member 205 because the second elongate member 205 has been extruded around the filaments. No cuts have been formed to include the heating filaments 215. In this example, the second elongate member 205 also includes a plurality of grooves 303. Because the heating filaments 215 are encapsulated within the second elongate member 205, the grooves 303 are not used to facilitate the formation of cuts for the inclusion of heating filaments.In this example, the grooves 303 may facilitate separation of the included heating filaments, making it easier to strip the individual cores when, for example, cutting the heating filaments.

[0096] [Fig. 3G] shows yet another example of a second elongate member 205 viewed in section. The second elongate member 205 has a generally triangular shape. In this example, the shape of the second elongate member 205 is similar to that of [Fig. 3C], but four filaments 215 are encapsulated within the second elongate member 205, all of which filaments are located in the center of the lower third of the second elongate member 205 and are arranged along a generally horizontal axis.

[0097] As explained above, it may be desirable to increase the distance between the filaments to improve thermal efficiency. In some embodiments, however, when heating filaments 215 are incorporated into the composite tube 201, the filaments 215 may be positioned relative to the center of the second elongate member 205. Central positioning is favorable for the strength of the composite tubing for reuse, in part because such positioning reduces the likelihood of filament breakage upon repeated flexing of the composite tube 201. Central positioning of the filaments 215 may also reduce the risk of creating an ignition hazard, because the filaments 215 are coated with insulating layers and separated from the gas path.

[0098] As explained above, some of the examples illustrate suitable positionings of filaments 215 in the second elongated member 205. In the above examples comprising more than one filament 215, the filaments 215 are generally aligned along a horizontal axis. Other configurations may also be used. For example, two filaments may be aligned along a vertical axis or along a diagonal axis. Four filaments may be aligned along a vertical axis or along a diagonal axis. Four filaments may be aligned in a cross configuration, with one filament disposed at the top of the second elongated member, one filament disposed at the bottom of the second elongated member (near the tube lumen), and two filaments disposed on opposite arms of a "T", a "Y", or the base of a triangle.

[0099] TABLES 1A and 1B set forth certain preferred dimensions of medical tubing described herein, as well as certain preferred ranges for those dimensions. The dimensions correspond to a cross-section of a tube. In these tables, lumen diameter represents the inner diameter of a tube. Pitch represents the distance between two repeat points measured axially along the tube, namely the distance between the tips of adjacent vertical "T" portions of the second elongate member. Bubble width represents the width (maximum outer diameter) of a bubble. Bubble height represents the height of a bubble from the tube lumen. Bead height represents the maximum height of the second elongate member from the tube lumen (e.g., the height of the vertical portion of the "T").The bead width represents the maximum width of the second elongated element (e.g. the width of the horizontal part of the "T"). The bubble thickness represents the thickness of the bubble wall.

[0100] [Tables 1 A] Feature Child Adult Dimension (mm) Range (±) Dimension (mm) Range (±) Lumen Diameter 11 1 18 5 Gap 4.8 1 7.5 2 Bubble Width 4.2 1 7 1 Bead Width 2.15 1 3.4 1 Bubble Height 2.8 1 4.0 0.5 Bead Height 0.9 0.5 1.7 0.5 Bubble Thickness 0.4 0.35 0.2 0.15

[0101] [TableslB] Feature Child Adult Dimension (mm) Range (±) Dimension (mm) Range (±) Lumen Diameter 11 1 18 5 Gap 4.8 1 7.5 2 Bubble Width 4.2 1 7 1 Bead Width 2.15 1 3.4 1 Bubble Height 2.8 1 4.0 0.5 Bead Height 0.9 0.5 1.7 0.5 Bubble Thickness 0.4 0.35 0.2 0.15

[0102] TABLES 2A and 2B show examples of tube feature dimension ratios for the tubes described in TABLES 1A and 1B respectively.

[0103] [Tables 2A] Ratios Child Adult Lumen Diameter: Spacing 2.3:1 2.4:1 Spacing: Bubble Width 1.1:1 1.1:1 Spacing: Bead Width 2.2:1 3.1:1 Bubble Width: Bead Width 2.0:1 2.9:1 Lumen Diameter: Bubble Height 3.9:1 5.1:1 Lumen Diameter: Bead Height 12.2:1 12.0:1 Bubble Height: Bead Height 3.1:1 2.3:1 Lumen Diameter: Bubble Thickness 27.5:1 90.0:1

[0104] [Tables2B] Ratios Child Adult Lumen Diameter: Gap 2.3:1 2.4:1 Gap: Bubble Width 1.1:1 1.1:1 Gap: Bead Width 2.2:1 2.2:1 Bubble Width: Bead Width 2.0:1 2.1:1 Lumen Diameter: Bubble Height 3.9:1 4.5:1 Lumen Diameter: Bead Height 12.2:1 10.6:1 Bubble Height: Bead Height 3.1:1 2.4:1 Lumen Diameter: Bubble Thickness 27.5:1 90.0:1

[0105] The following tables present certain examples of properties of a composite tube (referred to as "A"), described in the present document, comprising a heating filament integrated within the second elongated element. For comparison, the properties of a Fisher & Paykel RT100 model, a disposable corrugated tube (designated “B”) having a heating filament wound helically within the tube bore, are also shown.

[0106] A flow resistance (RAE) measurement was carried out according to Annex A of ISO 5367:2000(E). The results are summarized in Table 3. As seen below, the RAE for the composite tube is lower than the RAE for the RT 100 tube model.

[0107] [Tables3] RAE (cm H2O) Flow rate (1 / min) 3 20 40 60 A 0 0.05 0.18 0.38 B 0 0.28 0.93 1.99

[0108] Condensate or "condensation liquid" inside the tube refers to the weight of condensate collected per day at a gas flow rate of 20 1 / min and an ambient temperature of 18°C. Humidified air is continuously circulated through the tube from a chamber. The tube weights are recorded before and after each day of testing. Three consecutive tests are performed, with the tube being dried between each test. The results are shown below in Table 4. The results show that the weight of condensation liquid is significantly lower in the composite tube compared to the RT 100 tube model.

[0109] [Tables4] Tube A (Day 1) A (Day 2) A (Day 3) B (Day 1) B (Day 2) B (Day 3) Weight before (g) 136.20 136.70 136.70 111.00 111.10 111.10 Weight after (g) 139.90 140.00 139.20 190.20 178.80 167.10 Condensate weight (g) 3.7 3.3 2.5 79.20 67.70 56.00

[0110] The required power refers to the power consumed during the condensate test. In this test, the ambient air was maintained at 18°C. The humidification chambers (see for example humidification chamber 129 in [fig.l]) were powered by MR850 heating bases. The heating filaments in the tubes were powered independently from a power supply at direct current. The device was set to different flow rates and the chamber was allowed to stabilize at a temperature of 37 °C at the chamber outlet. Then, the direct current (DC) voltage to the circuits was varied to produce a temperature of 40 °C at the circuits outlet. The voltage required to maintain the temperature at the outlet 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 compared to tube B. This is because tube B uses a helical heating filament arranged in the tube bore to heat the gas from 37 °C to 40 °C. The composite tube generally does not heat the gas quickly because the heating filament is located in the tube wall (included in the second elongated member).Instead, the composite tube is designed to maintain gas temperature and prevent the formation of condensing liquid by keeping the tube bore at a temperature above the dew point of the humidified gas. [YES] [Tables5] Flow rate (1 / min) 40 30 20 Tube A, power required (W) 46.8 38.5 37.8 Tube B, power required (W) 28.0 27.5 26.8

[0112] The flexibility of the tubes was evaluated using a 3-point bend test. Tubes were placed in a 3-point bend test fixture and used in conjunction with an Instron 5560 Test System instrument to measure load and extension. Each tube specimen was evaluated three times; the tube extension against the applied load was measured to obtain respective average stiffness constants. The average stiffness constants for Tube A and Tube B are shown in Table 6.

[0113] [Tableauxô] Tube Rigidity (N / mm) A 0.028 B 0.088

[0114] Manufacturing Processes

[0115] Reference is then made to FIGS. 4A to 4F, which show examples of methods for manufacturing composite tubes.

[0116] Considering firstly [fig.4A], in at least one embodiment, a method of manufacturing a composite tube comprises providing the second elongate element 205 and spirally winding the second elongate element 205 around a mandrel 401, opposite side edges 403 of the second elongated member 205 being spaced apart on adjacent turns, thereby forming a second elongated member spiral 405. The second elongated member 205 may be wound directly around the mandrel in some embodiments. In other embodiments, a sacrificial layer may be disposed on the mandrel.

[0117] In at least one embodiment, the method further includes forming the second elongate member 205. Extrusion is a method that may be used to form the second elongate member 205. The second extruder may be configured to extrude the second elongate member 205 with a specified bead height. Thus, in at least one embodiment, the method includes extruding the second elongate member 205.

[0118] As shown in [fig.4B], extrusion may be advantageous because it may allow heating filaments 215 to be encapsulated within the second elongate member 205 as the second elongate member is formed 205, for example, using an extruder equipped with a crosshead extrusion die. Thus, in some embodiments, the method includes providing one or more heating filaments 215 and encapsulating the heating filaments 215 to form the second elongate member 205. The method may also include providing a second elongate member 205 having one or more heating filaments 215 included or encapsulated within the second elongate member 205.

[0119] In at least one embodiment, the method includes including one or more filaments 215 in the second elongated member 205. For example, as shown in [Fig.4C], the filaments 215 may be pressed (pulled or mechanically positioned) into the second elongated member 205 to a specified depth. Alternatively, cuts may be made in the second elongated member 205 to a specified depth, and the filaments 215 may be placed in the cuts. Preferably, the pressing or cutting occurs shortly after extrusion of the second elongated member 205 and the second elongated member 205 is soft.

[0120] As shown in FIGS. 4D and 4E, in at least one embodiment, the method includes providing the first elongate member 203 and spirally wrapping the first elongate member 203 around the spiral of the second elongate member 405, such that portions of the first elongate member 203 overlap adjacent turns of the spiral of the second elongate member 405, and a portion of the first elongate member 203 is disposed adjacent the mandrel 401 in the space between turns of the spiral of the second elongate member 405, thereby forming a spiral of the first elongate member 407. [Fig. 4D] shows an example of this method, in which heating filaments 215 are encapsulated in the second elongate member 205 before forming the spiral of the second elongate member. [Fig. 4E] shows an example of this method, in which heating filaments 215 are included in the second elongated member 205 as the spiral of the second elongated member is formed. Another method of integrating filaments 215 into the composite tube includes encapsulating one or more filaments 215 between the first elongated member 203 and the second elongated member 205 at a region where the first elongated member 203 overlaps the second elongated member 205.

[0121] The above-described variations for incorporating one or more heating filaments 215 into a composite tube have advantages over the variation in which the heating filaments are located in the gas passageway. The presence of the one or more heating filaments 215 outside the gas passageway improves performance because the filaments heat the wall of the tube where condensation is most likely to occur. This configuration reduces the risk of fire in high oxygen environments by separating the heating filament from the gas passageway. This feature also decreases performance because it reduces the efficiency with which the heating wires heat the gases passing through the tube. Regardless, in some embodiments, a composite tube 201 includes one or more heating filaments 215 positioned within the gas passageway.For example, heating filaments may be placed on the lumen wall (tube bore), such as in a spiral configuration. An exemplary method for placing one or more heating filaments 215 on the lumen wall includes bonding, embedding, or otherwise forming a heating filament on a surface of the second elongate member 205 which, after assembly, forms the lumen wall. Thus, in some embodiments, the method includes placing one or more heating filaments 215 on the lumen wall.

[0122] Whether the heating filaments 215 are included or encapsulated on the second elongated member 205 or disposed on the second elongated member 205, or otherwise placed in or on the tube, in at least one embodiment, pairs of filaments may be formed to produce a connecting loop at one end of the composite tube to form a circuit.

[0123] [Fig.4F] shows a longitudinal section of the assembly illustrated in [Fig.4E], and essentially represents an upper portion of the mandrel 401 and an upper portion of the spiral of the first elongate member 407 and the spiral of the second elongate member 405. This example shows that the spiral of the second elongate member 405 includes a second elongate member 205 in a T-shape. As the second elongate member is formed, heating filaments 215 are included in the second elongate member 205. The right side of [Fig.4F] shows the bubble-shaped profile of the spiral of the first elongate member, as described above.

[0124] The method may also include forming the first elongate element 203. The extrusion is a method that may be used for forming the first elongated member 203. Thus, in at least one embodiment, the method comprises extruding the first elongated member 203. The first elongated member 203 may also be manufactured by extruding two or more portions and joining these portions to form a single piece. As another alternative, the first elongated member 203 may also be manufactured by extruding sections that produce a hollow shape when formed or joined adjacently in a spiral tube forming process.

[0125] The method may also include supplying a gas, at a pressure greater than atmospheric pressure, to one end of the first elongate member 203. The gas may be, for example, air. Other gases may also be used, as explained above. Supplying a gas to one end of the first elongated member 203 may help the body maintain an 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 being wound around the mandrel 401, or after the first elongated member 203 has been wound around the mandrel 401. For example, an extruder equipped with a die head / nozzle combination may supply or introduce air into the hollow cavity of the first elongated member 203 while the first elongated member 203 is being extruded.Thus, in at least one embodiment, the method comprises extruding the first elongate member 203 and supplying a gas, at a pressure greater than atmospheric pressure, to one end of the first elongate member 203 after extrusion. A pressure of 15 to 30 cm H2O (or about 15 to 30 cm H2O) has been found to be suitable for this purpose.

[0126] In at least one embodiment, the first elongated member 203 and the second elongated member 205 are spirally wound around the mandrel 401. For example, the first elongated member 203 and the second elongated member 205 may exit an extrusion die at an elevated temperature of 200°C (or about 200°C) or higher, and then be applied to the mandrel after a short distance. Preferably, the mandrel is cooled using a water jacket, a cooler, and / or another cooling method suitable for this purpose, to a temperature of 20°C (or about 20°C) or lower, for example, a temperature close to 0°C (or about 0°C). After 5 (or about 5) spiral turns, the first elongated member 203 and the second elongated member 205 are further cooled by a cooling fluid (liquid or gas). In one embodiment, the cooling fluid is air emitted from a ring with jets encircling the mandrel.After cooling and removal of the constituent elements from the mandrel, a composite tube is formed, having a lumen extending along a longitudinal axis and a hollow space surrounding the lumen. In such an embodiment, no adhesive or other . No fastening mechanism is required to connect the first elongated member and the second elongated member. Other embodiments may use an adhesive or other fastening mechanism to bond or otherwise connect the two members. In another embodiment, the second elongated member 205, after extrusion and positioning of the heating filaments, may be cooled to freeze the location of the heating filaments. The second elongated member 205 may then be reheated when applied to the mandrel to improve the bond. Examples of reheating methods include the use of spot heaters, heat rollers, etc.

[0127] The method may also include forming pairs of heating filaments or sensing filaments to produce a connecting loop at one end of the composite tube. For example, end sections of two heating filaments or sensing filaments may be released from the second elongate member 205 and then formed to produce a connecting loop, for example by attaching, bonding, gluing, fusing, etc., the two filaments to each other. As another example, end sections of the heating filaments may be left free from the second elongate member 205 during the manufacturing process and then formed to produce a connecting loop when the composite tube is assembled.

[0128] Medical Tubing and Methods of Manufacturing Using a Single Spirally Wound Tube

[0129] Reference is then made to [Fig. 5A] through 5F which show cross-sections of tubing comprising a single tube-shaped member having a first elongated member or portion 203 and a second elongated member or portion 205. As illustrated, the second elongated portions 205 are formed integrally with the first elongated portions 203, and extend along the entire length of the single tube-shaped member.In the illustrated embodiments, the single tube-shaped member is an elongated hollow body having, in cross-section, a relatively thin wall partially defining the hollow portion 501, with two reinforcing portions 205 having a relatively greater thickness or stiffness on opposite sides of the elongated hollow body, adjacent the relatively thin wall. These reinforcing portions form a portion of the inner wall of the lumen 207 after the elongated hollow body has been spirally wound, such that these reinforcing portions are also spirally positioned between adjacent turns of the elongated hollow body.

[0130] In at least one embodiment, the method includes forming an elongate hollow body comprising the first elongate portion 203 and the reinforcing portion 205. Extrusion is one method that may be used for forming the elongate hollow body. Sectional shapes that may be used for the tube-shaped member are illustrated in FIGS. 5A-5F.

[0131] The elongated hollow body may be formed to produce medical tubing, as discussed above, and the foregoing discussion is incorporated by this reference. For example, in at least one embodiment, a method of manufacturing medical tubing includes spirally winding or wrapping the elongated hollow body around a mandrel. This may be performed at an elevated temperature, such that the elongated hollow body is cooled after being spirally wound to join adjacent turns together. As shown in [Fig. 5B], opposing side edges of the reinforcing portions 205 may touch on adjacent turns. In other embodiments, opposing side edges of the second elongated member 205 may overlap on adjacent turns, as shown in FIGS. 5D and 5E.Heating filaments 215 may be incorporated into the second elongate member, as explained above and as shown in FIGS. 5A-5F. For example, heating filaments may be disposed on opposite sides of the elongate hollow body as shown in FIGS. 5A-5D. Alternatively, heating filaments may be disposed on only one side of the elongate hollow body, as shown in FIGS. 5E-5F. Any of these embodiments could also incorporate the presence of sensing filaments.

[0132] Medical circuits

[0133] Reference is then made to [fig.6], which shows an example of a medical circuit according to at least one embodiment. The circuit comprises one or more composite tubes as described above, namely for the inspiration tube 103 and / or the expiration tube 117. The properties of the inspiration tube 103 and the expiration tube 117 are similar to those of the tubes described above with respect to [fig.l]. The inspiration tube 103 has an inlet 109, communicating with a humidifier 115, and an outlet 113, through which humidified gases are supplied to the patient 101. The expiration tube 117 also has an inlet 109, which receives the humidified gases exhaled by the patient, and an outlet 113. As described above with respect to [fig.l], the outlet 113 of the exhalation tube 117 may vent the exhaled gases to the atmosphere, or deliver the exhaled gases to the ventilation device / blower 115, to an air cleaner / filter (not shown here), or to any other location suitable for this purpose.

[0134] As described above, heating filaments 601 may be placed within the inhalation tube 103 and / or the exhalation tube 117, to reduce the risk of condensation liquid forming in the tubes by maintaining the temperature of the tube wall above the dew point temperature.

[0135] Constituent element of an insufflation system

[0136] Laparoscopic surgery, also called "minimally invasive surgery (MIS)" or "endoscopic surgery", is a surgical technique Modern laparoscopic surgery in which abdominal procedures are performed through small incisions (usually 0.5 to 1.5 cm), compared to the larger incisions required in traditional surgical procedures. Laparoscopic surgery involves procedures within the abdominal or pelvic cavity. During laparoscopic surgery with insufflation, it may be desirable to humidify the insufflation gas (usually CO2) before introducing it into the abdominal cavity. This can help prevent "dehydration" of the patient's internal organs and may decrease the amount of recovery time after surgery. Insufflation systems typically include humidification chambers that contain a quantity of water.The humidifier typically includes a heating plate that heats water to produce water vapor, which is introduced into the incoming gases to humidify the gases. The gases are transported out of the humidifier along with the water vapor.

[0137] Reference is then made to [fig.7], which shows an insufflation system 701 according to at least one embodiment. The insufflation system 701 comprises an insufflator 703 which produces a flow of insufflation gases, at a pressure higher than atmospheric pressure, for introduction into the abdominal or peritoneal cavity of the patient 705. The gases pass into a humidifier 707, comprising a heating base 709 and a humidification chamber 711, the chamber 711, in use, being in contact with the heating base 709, so that the heating base 709 provides heat to the chamber 711. In the humidifier 707, the insufflation gases pass through the chamber 711 so that they become humidified, reaching an appropriate humidity level.

[0138] The system 701 includes a delivery conduit 713 that connects the humidification chamber 711 and the peritoneal cavity or surgical site of the patient 705. The conduit 713 has a first end and a second end, the first end being connected to the outlet of the humidification chamber 711 and receiving the humidified gases from the chamber 711. The second end of the conduit 713 is inserted into the surgical site or peritoneal cavity of the patient 705 and the humidified insufflation gases flow from the chamber 711, through the conduit 713, and into the surgical site to insufflate and dilate the surgical site or peritoneal cavity. The system also includes a controller (not shown here) that regulates the amount of humidity supplied to the gases by controlling the power supplied to the heating base 709. The controller can also be used to monitor the water in the humidification chamber 711.A smoke evacuation system 715 is shown exiting the body cavity of the patient 705.

[0139] The smoke evacuation system 715 can be used in conjunction with the insufflation system 701 described above, or it may be used with other insufflation systems suitable for this purpose. The smoke evacuation system 715 includes an exhaust or outlet branch 717, an exhaust assembly 719, and a filter 721. The exhaust branch 717 connects the filter 721 and the exhaust assembly 719, which in use is positioned in or adjacent to the surgical site or peritoneal cavity of the patient 705. The exhaust branch 717 is a self-supporting tube (i.e., the tube is capable of supporting its own weight without collapsing) having two open ends: one end corresponding to the surgical site, and an outlet end.

[0140] At least one embodiment incorporates the realization that using a composite tube as conduit 713 allows humidified gases to be delivered to the patient's surgical site 705 while minimizing heat loss. This may have the advantage of reducing overall energy consumption in the insufflation system, as less heat input is required to compensate for the heat loss.

[0141] Coaxial tube

[0142] A coaxial breathing tube may also comprise a composite tube as described above. In a coaxial breathing tube, a first gas space is an inspiratory limb or an exhalation limb, and the second gas space is the other of the inspiratory limb or the exhalation limb. A gas flow path is disposed between the inlet of said inspiratory limb and the outlet of said inspiratory limb, and a gas flow path is disposed between the inlet of said exhalation limb and the outlet of said exhalation limb. In one embodiment, the first gas space is said inspiratory limb, and the second gas space is said exhalation limb. Alternatively, the first gas space may be the exhalation limb, and the second gas space may be the inspiratory limb.

[0143] Reference is then made to [fig.7], which shows a coaxial tube 701 according to at least one embodiment. In this example, the coaxial tube 701 is disposed between a patient 701 and a ventilator 705. The exhalation gases and the inspiration gases each circulate in one of the inner tube 707 or the space 709 between the inner tube 707 and the outer tube 711. It will be noted that the outer tube 711 may not be exactly aligned with the inner tube 707. The term "coaxial" rather designates a tube located inside another tube.

[0144] For reasons related to heat transfer, the inner tube 707 can transport the inspiration gases in the space 713 located inside said tube, while the expiration gases are transported in the space 709 between the inner tube 707 and the tube outer tube 711. This airflow configuration is indicated by arrows. However, a reverse configuration is also possible, in which the outer tube 711 carries the inspiratory gases and the inner tube 707 carries the exhalation gases.

[0145] In at least one embodiment, the inner tube 707 is formed from a corrugated tube, for example a Fisher & Paykel model RT 100, which is a disposable tube. The outer tube 711 may be formed from a composite tube, as described above.

[0146] With a coaxial tube 701, the ventilator 705 may not detect a leak in the inner tube 707. This leak may short-circuit the patient 701, so that the patient 701 will not receive a sufficient amount of oxygen. This short-circuit may be detected by positioning a sensor at the end of the coaxial tube 701 that corresponds to the patient. This sensor may be positioned in the connector of the end that corresponds to the patient 715. If a short-circuit is present closer to the ventilator 705, the patient 701 will continually re-inhale the volume of air close to the patient 701. This will cause the carbon dioxide concentration in the space where the inspiration gas circulates 713 near the patient 701 to rise, and this rise may be detected directly by a CO2 sensor. This sensor may include any of the various such sensors currently commercially available.Alternatively, such rebreathing may be detected by monitoring the temperature of the gases at the patient end connector 715, with an increase in temperature above a predetermined level indicating that rebreathing is occurring.

[0147] In addition to the above features, to reduce or eliminate the formation of condensation within either the inner tube 707 or the outer tube 711, and to maintain a substantially uniform temperature in the gases flowing in the coaxial tube 701, a heating device, such as a resistance heating filament, may be disposed within either the inner tube 707 or the outer tube 711, disposed within the gas spaces 709 or 713, or disposed within the walls themselves of the inner tube 707 or the outer tube 711.

[0148] Thermal properties

[0149] In embodiments of a composite tube 201 incorporating a heating filament 215, heat may be lost through the walls of the first elongate member 203, resulting in non-uniform heating. As discussed above, one method for compensating for these heat losses is to apply an external heating source to the walls of the first elongate member 203, which helps regulate the temperature and compensate for the heat loss. However, other methods for optimizing thermal properties may also be used.

[0150] Reference is then made to FIGS. 9A to 9C, which show examples of confi- bubble height (i.e., the cross-sectional height of the first elongate member 203, measured from the surface facing the inner lumen to the surface forming the maximum outer diameter) to improve thermal properties.

[0151] The dimensions of the bubble may be selected to reduce heat loss from the composite tube 201. Generally, increasing the bubble height increases the effective thermal resistance of the tube 201, because a greater bubble height allows the first elongate member 203 to contain more insulating air. However, it has been discovered that at a certain bubble height, changes in air density cause convection within the tube 201, thereby increasing heat loss. In addition, at a certain bubble height, the surface area becomes so large that the heat lost through the surface outweighs the benefits provided by increasing the bubble height. Some implementations incorporate awareness of these facts.

[0152] The radius of curvature and the curvature of the bubble can be useful in determining a desirable bubble height. The curvature of an object is defined as the inverse of the radius of curvature of that object. Therefore, the greater the radius of curvature of an object, the less curved the object is. For example, a flat surface would have an infinite radius of curvature (oo), and therefore a curvature of 0.

[0153] [Fig.9A] shows a longitudinal section of an upper portion of a composite tube. [Fig.9A] shows an embodiment of a composite tube 201 where the bubble has a significant height. In this example, the bubble has a relatively small radius of curvature, and therefore a significant curvature. In addition, the bubble has a height that is approximately three to four times greater than the height of the second elongate member 205.

[0154] [Fig.9B] shows a longitudinal section of an upper portion of another composite tube. [Fig.9B] shows an embodiment of a composite tube 201 where the upper portion of the bubble is flattened. In this example, the bubble has a very large radius of curvature, but a small curvature. In addition, the height of the bubble is approximately the same as the height of the second elongate member 205.

[0155] [Fig.9C] shows a longitudinal section of an upper portion of another composite tube. [Fig.9C] shows an embodiment of a composite tube 201 where the bubble width is greater than the bubble height. In this example, the bubble has a radius of curvature and curvature between those of [Fig.9A] and [Fig.9B], and the center of the radius for the upper portion of the bubble is outside the bubble (as compared to [Fig.9A]). The inflection points on the left and right sides of the bubble are approximately in the middle (in the height direction) of the bubble (and not in the lower portion of the bubble, as in [Fig.9A]). In addition, the height of the bubble is approximately twice the height of the second elongated element 205, thus producing a bubble height between those of [fig.9A] and [fig.9B].

[0156] The configuration of [fig.9A] produced the lowest heat loss from the tube. The configuration of [fig.9B] produced the highest heat loss from the tube. The configuration of [fig.9C] produced a heat loss intermediate between the configurations of FIGS. 9A and 9B. However, the large external surface area and the convection heat transfer in the configuration of [fig.9A] produced poor thermal efficiency. Thus, among the three bubble arrangements of FIGS. 9A-9C, [fig.9C] was found to have the best overall thermal properties. When the same thermal energy was supplied to all three tubes, the configuration of [fig.9C] achieved the greatest temperature rise along the length of the tube. The bubble of [fig.9C] is large enough to increase the insulation air volume, but not large enough to cause significant heat loss by convection. The configuration in [fig.9B] was found to have the poorest thermal properties, namely the configuration in [fig.9B] achieved the lowest temperature rise along the length of the tube. The configuration in [fig.9A] produced intermediate thermal properties and achieved a lower temperature rise than the configuration in [fig.9C].

[0157] It will be understood that although the configuration of [Fig. 9C] may be preferred in some embodiments, other configurations, including those of FIGS. 9A, 9B, and other variations, may be used as desired in other embodiments.

[0158] TABLE 7 shows the bubble height, tube outer diameter, and radius of curvature of the configurations illustrated in each of FIGS. 9A, 9B, and 9C.

[0159] [Tables7] Tube (Fig.) 9A 9B 9C Bubble height (mm) 3.5 5.25 1.75 Outside diameter (mm) 21.5 23.25 19.75 Radius of curvature (mm) 5.4 3.3 24.3

[0160] TABLE 7A shows the bubble height, outer diameter (D1, D2, D3) and radius of curvature (RI, R2, R3) of other configurations illustrated in FIGS. 11A, 11B, and 11C.

[0161] [Tables? A] Tube (Fig.) 11A 11B 11C Bubble height (mm) 6.6 8.4 9.3 Outside diameter (mm) 24.6 26.4 27.3 Radius of curvature (mm) 10 8.7 5.7

[0162] It will be noted that in general, the smaller the radius of curvature, the greater the degree of bending the tube can undergo without collapsing or "kinking" the bubble. For example, [Fig. 1 1D] shows a tube that has been bent beyond its radius of curvature RI (more specifically, it shows the tube of [Fig. HA] bent to a radius of curvature of 5.7 mm), thereby causing a kink in the bubble walls. Kinking is generally undesirable, as it can impair the appearance of the tube, and can decrease the thermal properties of the tube.

[0163] Accordingly, in some applications, configurations having superior flexural properties (such as those shown in FIGS. 9A or 9B) may be desirable, despite thermal properties having lower efficiency. In some applications, it has been found that a tube having an outside diameter of 25 mm to 26 mm (or about 25 mm to about 25 mm) produces a good balance of thermal efficiency, flexibility, and flexural performance. It will be noted that although the configurations of FIGS. 9A and 9B may be preferred in some embodiments, other configurations, including those of FIGS. 11 A1-1D and other variations, may be used as desired in other embodiments.

[0164] Reference is then made to FIGS. 9C-9F, which show examples of positioning the heating element 215 with similar bubble shapes to improve thermal properties. The location of the heating element 215 may change the thermal properties within the composite tube 201.

[0165] [Fig.9C] shows a longitudinal section of an upper portion of another composite tube. [Fig.9C] shows an embodiment of a composite tube 201 where the heating elements 215 are positioned centrally within the second elongate member 205. This example shows that the heating elements 215 are close to each other and are not close to the bubble wall.

[0166] [Fig.9D] shows a longitudinal section of an upper portion of another composite tube. [Fig.9D] shows an embodiment of a composite tube 201 in which the heating elements 215 are spaced further apart, compared to [Fig.9C], in the second elongate element 205. These heating elements are closer to the bubble wall and produce better thermal regulation within the tube. composite 201.

[0167] [Fig.9E] shows a longitudinal section of an upper portion of another composite tube. [Fig.9E] shows an embodiment of a composite tube 201 in which the heating elements 215 are spaced above each other in the vertical axis of the second elongate element 205. In this example, the heating elements 215 are also close to each wall of the bubble.

[0168] [Fig.9F] shows a longitudinal section of an upper portion of another composite tube. [Fig.9F] shows one embodiment of a composite tube 201 where the heating elements 215 are spaced at opposite ends of the second elongate member 205. The heating elements 215 are close to the bubble wall, particularly as compared to FIGS. 9C-9E.

[0169] Of the four filament arrangements of FIGS. 9C-9F, [fig.9F] was found to have the best thermal properties. Due to their similar bubble shapes, all configurations experienced similar heat loss from the tube. However, when the same thermal energy was supplied to the tubes, the filament configuration of [fig.9F] achieved the greatest temperature rise along the length of the tube. The configuration of [fig.9D] was found to have the next best thermal properties, and achieved the next greatest temperature rise along the length of the tube. The performance produced by the configuration of [fig.9C] was next. The configuration of [fig.9E] produced the poorest performance and achieved the lowest temperature rise along the length of the tube, when the same amount of heat was supplied.

[0170] It will be understood that although the configuration of [fig.9F] may be preferred in some embodiments, other configurations, including those of FIGS. 9C, 9D, 9E, and other variations, may be used as desired in other embodiments.

[0171] Reference is then made to FIGS. 10A-10C, which show exemplary configurations for the superposition of the first elongate member 203. It has been discovered that heat distribution can be improved, in some embodiments, by superimposing multiple bubbles. These embodiments may be more beneficial when using an internal heating filament 215. [Fig. 10A] shows a longitudinal section of an upper portion of another composite tube. [Fig. 10A] shows a section of a composite tube 201 without any superposition.

[0172] [Fig.10B] shows a longitudinal section of an upper portion of another composite tube. [Fig.10B] shows another example of a composite tube 201 with superimposed bubbles. In this example, two bubbles are superimposed on each other to form the first elongate element 203. Compared to [Fig.10A], the total bubble height is maintained, but the bubble spacing is half that of [fig.lOA]. In addition, the [fig.lOB] embodiment has only a slight reduction in air volume. The superposition of the bubbles reduces natural convection and heat transfer in the inter-bubble space 213 and decreases the overall thermal resistance. The heat flow path is extended in the superimposed bubbles, allowing heat to be more easily distributed throughout the composite tube 201.

[0173] [Fig.10C] shows a longitudinal section of an upper portion of another composite tube. [Fig.10C] shows another example of a composite tube 201 with superimposed bubbles. In this example, three bubbles are superimposed on each other to form the first elongate member 203. Compared to [Fig.10A], the total bubble height is maintained, but the bubble spacing is one-third that of [Fig.10A]. In addition, the embodiment of [Fig.10B] has only a slight reduction in air volume. The superposition of the bubbles reduces natural convection and heat transfer in the space between the bubbles 213.

[0174] Cleaning

[0175] In at least one embodiment, the materials used for a composite tube may be selected to withstand various cleaning processes. In some embodiments, a high level of disinfection (about 20 cleaning cycles) may be used to clean the composite tube 201. During high level disinfection, the composite tube 201 is pasteurized at about 75°C for about 30 minutes. Next, the composite tube 201 is immersed in a 2% glutaraldehyde medium for about 20 minutes. The composite tube 201 is removed from the glutaraldehyde and immersed in a 6% hydrogen peroxide medium for about 30 minutes. Finally, the composite tube 201 is removed from the hydrogen peroxide and immersed in a 0.55% orthophthalaldehyde (OPA) medium for about 10 minutes.

[0176] In other embodiments, sterilization (about 20 cycles) may be used to clean the composite tube 201. First, the composite tube 201 is placed inside a steam autoclave at about 121°C for about 30 minutes. Then, the temperature of the steam autoclave is increased to about 134°C for about 3 minutes. After autoclaving, the composite tube 201 is immersed in a 100% ethylene oxide (ETO) gas medium. Finally, the composite tube 201 is removed from the ETO gas medium and immersed in a medium of about 2.5% glutaraldehyde for about 10 hours.

[0177] The composite tube 201 may be made of materials that allow it to withstand repeated cleaning. In some embodiments, some or all of the composite tube 201 may be made of, without limitation, thermoplastic elastomers. styrene-ethylene-butene-styrene blocks, for example Kraiburg TF6STE. In other embodiments, the composite tube 201 may be made of, without limitation, hytrel, urethanes, or silicones.

[0178] The foregoing description of the invention includes preferred forms thereof. Modifications may be made therein without departing from the scope of the invention. Numerous changes in construction and widely different embodiments and applications of the invention will occur to those skilled in the art to which the invention relates, without departing from the scope of the invention as defined in the appended claims. The disclosures and descriptions contained herein are illustrative only and should not be construed as limiting in any sense.

Claims

Claims

1. A composite tube (201) for use in medical circuits for supplying gas to and / or removing gas from a patient, the composite tube (201) comprising: a first elongate member (203) comprising a hollow body spirally wound to at least partially form an elongate tube having a longitudinal axis (LA), a lumen (207) extending along the longitudinal axis, and a hollow wall at least partially surrounding the lumen, wherein the first elongate member (203) forms in section along the longitudinal axis a flattened surface at the lumen and a curvature distal to the lumen (207); and a second elongate member (205) spirally wound and joined between adjacent turns of the first elongate member (203), the second elongate member forming at least a portion of the lumen of the elongate tube.

2. A composite tube according to claim 1, wherein the lumen (207) has a smooth lumen surface.

3. A composite tube according to any preceding claim, wherein the second elongate member (205) has a longitudinal cross-section which is triangular and / or portions of the first elongate member (203) overlap adjacent turns of the second elongate member (205).

4. A composite tube according to any preceding claim, wherein the second elongate member (205) is less flexible than the first elongate member (203) and / or the second elongate member (205) is solid or substantially solid.

5. A composite tube according to any preceding claim, wherein the joined and spirally wound first and second elongate members (203, 205) are configured to provide crush resistance while being flexible enough to allow flexures over a small radius without causing twisting, obstruction or collapse.

6. A composite tube according to any preceding claim, wherein the first elongate member (203) forms, in longitudinal cross-section, a plurality of bubbles with a flattened surface at the lumen.

7. A composite tube according to claim 6, wherein adjacent bubbles are separated by a gap (213) above the second elongate member (205).

8. A composite tube according to claim 7, wherein the gap (213) is configured to allow flexures over a smaller radius.

9. A composite tube according to any one of claims 6 to 8, wherein the bubbles have perforations.

10. A composite tube according to any preceding claim, comprising one or more conductive filaments (215) included or encapsulated in the second elongate member (205), the one or more conductive filaments (215) comprising a heating filament and / or a sensing filament.

11. A composite tube according to claim 10, comprising four of said conductive filaments (215) and / or wherein pairs of conductive filaments (215) are formed in a connecting loop at one end of the composite tube.

12. A composite tube according to claim 10 or 11, wherein the one or more filaments (215) are spaced from the lumen wall (207).

13. A composite tube according to any one of claims 10 to 12, wherein the second elongate member (205) has a longitudinal cross-section that is generally triangular, generally T-shaped or generally Y-shaped, and the one or more conductive filaments (215) are included or encapsulated within the second elongate member (205) on opposite sides of the triangle, T-shape or Y-shape.

14. A composite tube (201) according to any preceding claim, being one or more of: a constituent element of a medical circuit, an inspiration tube, an expiration tube, a constituent element of a PAP system, a constituent element of an insufflation circuit, a constituent element of an exploration system and a surgical constituent element.

15. A method of manufacturing a composite tube (201) according to claim 1 for use in medical circuits for supplying gases to and / or extracting gases from a patient, the method comprising the steps of: providing a first elongate member (203) comprising a hollow body and a second elongate member (205) configured to provide structural support to the first elongate member (203); spirally wrapping the second elongate member (205) around a mandrel, opposite side edge portions of the second elongate member (205) being spaced apart on adjacent turns, thereby forming a second elongate member spiral (205); and spirally winding the first elongate member (203) around the second elongate member spiral (205), such that portions of the first elongate member (203) overlap adjacent turns of the second elongate member spiral (205) and a portion of the first elongate member (203) is disposed adjacent the mandrel in the space between turns of the second elongate member spiral (205), thereby forming a first elongate member spiral (203), wherein the second elongate member (205) has a longitudinal cross-section that is wider proximate a lumen (207) and narrower radially away from the lumen (207).

16. The method of claim 15, comprising forming the first elongate member (203) and / or forming the second elongate member (205).

17. A method according to claim 15 or 16, comprising including or encapsulating one or more conductive filaments (215) in the second elongate member (205),

18. The method of claim 15 or 17, comprising forming the second elongate member (205), wherein the step of forming the second elongate member (205) comprises the step of extruding the second elongate member (205) with a second extruder.

19. The method of claim 18, wherein the second extruder is configured to include or encapsulate one or more conductive filaments (215) within the second elongate member (205).

20. The method of claim 19, wherein the conductive filaments (215) are not reactive with the second elongate member (105) and / or the conductive filaments (215) comprise aluminum or copper.

21. A method according to claim 19 or 20, comprising the step of forming pairs of conductive filaments (215) in a connecting loop at one end of the composite tube.

22. A method according to claim 15 or one of claims 17 to 21, comprising forming the first elongate member (203), wherein the step of forming the first elongate member (203) comprises the step of extruding the first elongate member (203) with a first extruder.

23. A method according to claim 22 as dependent on claim 18, wherein the first extruder is separate from the second ex- truder.

24. A method according to any one of claims 15 to 23, comprising supplying air at a pressure greater than atmospheric pressure to one end of the first elongate member (203),

25. A method according to one of claims 15 to 24, comprising cooling the spiral of the second elongate member (205) and the spiral of the first elongate member (203) to form a composite tube having a lumen (207) extending along a longitudinal axis and a hollow space surrounding the lumen (207).

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