Medical gas catheter

Abstract

A catheter for delivering a medical gas includes an elongate tube, a sheath disposed around the elongate tube, and a pair of connectors disposed at opposite ends of the elongate tube. The elongated tube is formed of a breathable material to mitigate condensation within the lumen. In use, water molecules within the lumen of the elongate tube are dissipated by being absorbed into the breathable material, diffused through the breathable material, and desorbed to ambient air. The breathable material may tend to swell and soften upon absorption of water molecules. Expansion of the elongated tube may be selectively constrained by the sheath. The restraint of the sheath may mitigate softening of the breathable material.

Description

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 329,205, entitled "RESPIRATORY CONDUIT," which is incorporated herein by reference in its entirety. background Technical Field

[0003] The present disclosure relates to a catheter for delivering medical gases. More particularly, although not exclusively, the present disclosure relates to a catheter for use in a breathing circuit of a respiratory assistance system or an insufflation circuit of a surgical insufflation system, the catheter comprising a gas permeable material that is permeable to water molecules. Background Art

[0004] It has been shown that for patients receiving respiratory assistance, there are clinical benefits when the temperature and humidity of the breathing gases supplied to the patient by the respiratory assistance system mimic the levels that occur naturally in healthy lungs (typically about 37°C and 100% relative humidity). Thus, the breathing gases can be heated and humidified to improve patient comfort and recovery.

[0005] Similarly, there are clinical benefits to heating and humidifying the insufflation gas supplied by a surgical insufflation system to the abdominal or peritoneal cavity of a patient (e.g., during laparoscopic surgery). The insufflation gas can be supplied from a gas bottle stored at room temperature (e.g., between about 19 degrees Celsius and 21 degrees Celsius) and with a relative humidity close to 0%. Heating and humidifying the insufflation gas can reduce cell damage or desiccation, limit the formation of adhesions, or reduce other deleterious effects.

[0006] In a medical gas system (e.g., a respiratory assistance system or a surgical insufflation system), medical gas (respiratory gas or insufflation gas, respectively) can be delivered to and from a patient through a catheter. The catheter has a tube wall that defines a lumen for passing the medical gas. The outer surface of the tube wall is typically exposed to ambient air surrounding the outer surface of the catheter. The ambient air is typically at a relatively lower temperature and humidity than the heated and humidified medical gas flow within the lumen. In a hospital environment, for example, one or more of the temperature and humidity of the ambient air is typically regulated by the hospital heating, ventilation, and air conditioning (HVAC) system to achieve comfort and air quality. In other environments (e.g., a patient's home), one or more of the temperature and humidity of the ambient air may be regulated or not. The temperature and humidity of the ambient air can fluctuate greatly throughout the day and seasons, especially if they are not regulated.

[0007] The temperature difference between the medical gas and the ambient air causes the heated and humidified medical gases to be cooled as they pass along the length of the catheter. If the temperature of the medical gas drops below the dew point, the water vapor in the medical gas stream will condense into liquid droplets.

[0008] Condensate may also form upstream and downstream of the catheter. For example, in a respiratory assistance system, high humidity of the respiratory gas delivered by the expiratory catheter to the ventilator or anesthesia machine may cause condensation to form within the ventilator or anesthesia machine. Condensate may accumulate in filters or on flow sensors within the ventilator or anesthesia machine.

[0009] Condensate and other liquids may be drained into one or more of the catheters from other sources (eg, one or more of a nebulizer, a Y-piece, a catheter mount, a patient interface, a patient, etc.).

[0010] Condensate or other liquids that accumulate in tubing or other components of a medical gas system may cause a variety of problems, such as one or more of the following:

[0011] · Incorrect sensor readings;

[0012] Filter saturation;

[0013] Alarms (e.g., auditory and visual);

[0014] Damage to the flow source or its components (e.g., flow sensor);

[0015] the need for periodic drainage, which may interrupt surgery or treatment; and

[0016] • Blockage of flow paths. Summary of the invention

[0017] In a first aspect, a medical gas conduit for a medical gas system comprises: an elongated tube defining a lumen for passing a flow of medical gas, at least a portion of the elongated tube comprising a gas-permeable material, the gas-permeable material being configured to expand during use due to absorption of water molecules; and a sheath disposed around at least a portion of the elongated tube, wherein the sheath is configured to constrain expansion of at least a portion of the elongated tube in at least one of a radial direction and a longitudinal direction during use due to absorption of water molecules by the gas-permeable material.

[0018] In a second aspect, a medical gas conduit for a medical gas system comprises: an elongated tube defining a lumen for passing a flow of medical gas, at least a portion of the elongated tube being corrugated and comprising: a gas-permeable material and a plurality of corrugations, the gas-permeable material being configured to expand during use due to absorption of water molecules; and a sheath being arranged around at least a portion of the elongated tube and being configured to constrain expansion of the elongated tube at least in a longitudinal direction of the elongated tube during use; wherein the elongated tube is configured such that a spacing of the plurality of corrugations changes during use depending on absorption of water molecules by the gas-permeable material and constraint of the elongated tube by the sheath.

[0019] In a third aspect, a medical gas conduit for a medical gas system comprises: an elongated tube defining a lumen for passing a flow of medical gas, at least a portion of the elongated tube comprising a gas permeable material configured to expand due to absorption of water molecules during use; and a sheath disposed around at least a portion of the elongated tube, each end of the sheath being fixed to a corresponding end of the elongated tube, wherein the sheath is configured such that in use, a length and a diameter of the sheath change in inverse proportion to each other when the gas permeable material expands due to absorption of water molecules.

[0020] In a fourth aspect, a medical gas conduit for a medical gas system comprises: an elongated tube defining a lumen for flowing medical gas therethrough; a sheath disposed around at least a portion of the elongated tube; and a pair of connectors for pneumatically coupling the elongated tube to other components of a respiratory system, each connector of the pair of connectors securing a respective end of the sheath relative to a corresponding end of the elongated tube, and at least a first connector of the pair of connectors comprising a plurality of apertures through which one or more of the elongated tube and the sheath are exposed.

[0021] In a fifth aspect, a medical gas conduit for a medical gas system comprises: an elongated tube defining a lumen for flowing medical gas therethrough; and a sheath disposed around at least a portion of the elongated tube, wherein the sheath is configured to be at least partially spaced apart from a maximum outer diameter of the elongated tube when the medical gas conduit is in an equilibrium state.

[0022] In a sixth aspect, a medical gas conduit for a medical gas system comprises: an elongated tube defining a lumen for passing a flow of medical gas, at least a portion of the elongated tube comprising a gas permeable material, the gas permeable material being configured to expand when absorbing water molecules during use; and a sheath being arranged around at least a portion of the elongated tube and being configured to selectively constrain expansion of the elongated tube due to absorption of water molecules during use; wherein the elongated tube and the sheath are configured such that, under at least some conditions, the compliance of the medical gas conduit depends on the physical interaction between the elongated tube and the sheath.

[0023] In a seventh aspect, a medical gas conduit for a medical gas system comprises: an elongated tube defining a lumen for flowing medical gas therethrough, at least a portion of the elongated tube comprising a gas permeable material configured to expand when absorbing water molecules during use; and a sheath loosely arranged around at least a portion of the elongated tube; wherein the elongated tube is configured to apply hoop stress to the sheath under at least some conditions during use.

[0024] In an eighth aspect, a medical gas conduit for a medical gas system comprises: an elongated tube defining a lumen for passing a flow of medical gas therethrough; and a sheath disposed around at least a portion of the elongated tube, the sheath comprising a braided tubular mesh comprising a biaxial braid comprised of a plurality of braided elements spaced apart around a periphery of the sheath and extending helically around the elongated tube, the plurality of braided elements each comprising a pair of adjacent filaments.

[0025] In a ninth aspect, a medical gas conduit for a medical gas system comprises: an elongated tube defining a lumen for passing a flow of medical gas, at least a portion of the elongated tube comprising a gas permeable material, at least a portion of the elongated tube being configured to absorb between about 100% and 250% of its own dry mass, preferably between about 100% and 180%, more preferably between about 110% and 150%, still more preferably between about 120% and 140% or between about 130% and 145%, and still more preferably between about 135% and 145%, for example about 138% or 139%, of water molecules in an immersion test.

[0026] In a tenth aspect, a medical gas conduit for a medical gas system comprises: an elongated tube defining a lumen for passing a flow of medical gas, at least a portion of the elongated tube comprising a gas permeable material, at least a portion of the elongated tube being configured to absorb between about 40% and 80%, preferably between about 40% and 60%, more preferably between about 45% and 55%, and still more preferably between about 48% and 51%, for example about 49%, of its own dry mass in an immersion test, and the medical gas conduit does not include a heating wire.

[0027] In an eleventh aspect, a medical gas conduit for a medical gas system comprises: an extruded elongated tube defining a lumen for passing medical gas, at least a portion of the elongated tube comprising a gas permeable material; and a pair of connectors at respective ends of the elongated tube for pneumatically connecting the medical gas conduit to other components of the medical gas system, at least one of the pair of connectors comprising: a first connector component at least partially inserted into the lumen of the elongated tube, and a second connector component overmolded to the first connector component and the elongated tube.

[0028] In a twelfth aspect, a medical gas conduit for a medical gas system comprises: an elongated tube defining a lumen for passing a medical gas flow, at least a portion of the elongated tube comprising a gas permeable material, the gas permeable material comprising two melting points in a differential scanning calorimetry (DSC) test, each melting point having a temperature above about 197°C, preferably above about 202°C, more preferably above about 204°C, still more preferably above about 205°C, and most preferably above about 206°C, for example a temperature equal to or above about 207°C, wherein the medical gas conduit does not include a heating wire.

[0029] In a thirteenth aspect, a medical gas conduit for a medical gas system comprises: an elongated tube defining a lumen for passing a flow of medical gas, at least a portion of the elongated tube comprising a gas permeable material comprising three melting points in a differential scanning calorimetry (DSC) test, wherein the medical gas conduit does not include a heating wire.

[0030] In a fourteenth aspect, a medical gas conduit for a medical gas system comprises: an elongated tube defining a lumen for flowing a medical gas therethrough, at least a portion of the elongated tube comprising a gas permeable material comprising a minimum melting point in a differential scanning calorimetry (DSC) test, the minimum melting point having a temperature greater than about 37°C, preferably greater than about 42°C, more preferably greater than about 44°C, more preferably greater than about 45°C, and still more preferably greater than about 46°C, for example at a temperature of about 47°C.

[0031] In a fifteenth aspect, a medical gas conduit for a medical gas system comprises: an elongated tube defining a lumen for flowing medical gas therethrough, at least a portion of the elongated tube comprising a gas permeable material configured to expand in use due to absorption of water molecules, wherein the medical gas conduit is configured such that in use in at least one conditional state the elongated tube has a localized expansion in one or more of the following: an inlet region proximal to a patient interface of the medical gas system and including up to about 50%, preferably up to about 33%, more preferably up to about 25%, and even more preferably up to about 10% of the length of the elongated tube; Preferably, up to about 20%, and most preferably, up to about 10%; an outlet area, which is closest to the gas return inlet of the gas source of the medical gas system and includes up to about 50% of the length of the elongated tube, preferably up to about 33%, more preferably up to about 25%, more preferably up to about 20%, and most preferably up to about 10%; and an intermediate area, which is between the inlet area and the outlet area and includes up to about 50% of the length of the elongated tube, preferably up to about 33%, more preferably up to about 25%, more preferably up to about 20%, and most preferably up to about 10%.

[0032] The medical gas conduit of any one of the ninth to fifteenth aspects may include a sheath disposed around at least a portion of the elongate tube.

[0033] The medical gas conduit of any one of the fourth, fifth and eighth aspects may comprise an elongate tube comprising a gas permeable material.

[0034] The following technical features may be applicable to the medical gas conduit described in any one of the first to fifteenth aspects.

[0035] The medical gas conduit may be an expiratory conduit, the medical gas system may be a respiratory assistance system, and the medical gas flow may be a respiratory gas flow. Alternatively, the medical gas conduit may be an inspiratory conduit, the medical gas system may be a respiratory assistance system, and the medical gas flow may be a respiratory gas flow. Alternatively, the medical gas conduit may be an exhaust conduit, the medical gas system may be a surgical insufflation system, and the medical gas flow may be an insufflation gas flow.

[0036] The diameter and length of at least one, and preferably both, of the elongate tube and the sheath may be temporarily varied in use.

[0037] The length and diameter of the sheath may be configured to change in an inverse relationship in use as the elongated tube expands due to absorption of water molecules.

[0038] The length and diameter gradient of the sheath may be between about -100 and -20, preferably between about -50 and -20, more preferably between about -40 and -35, and most preferably about -37. Alternatively, the length and diameter gradient of the sheath may be between about -75 and -25, preferably between about -60 and -40, more preferably between about -55 and -45, and most preferably about -52.

[0039] The length and diameter gradient of the sheath may be substantially linear when the diameter of the sheath is between about 24 mm and 32 mm.

[0040] When separated from the sheath, the sheath may be configured to conform to a rod having an outer diameter ranging between approximately 23 mm and 43 mm.

[0041] The sheath may comprise a plurality of openings, preferably quadrilateral openings, arranged to undergo an affine transformation in use when the elongate tube expands due to absorption of water molecules by the gas permeable material.

[0042] The sheath may be configured to be at least partially spaced apart from the elongate tube when the medical gas conduit is in at least one of a dry state and an equilibrium state, and preferably both.

[0043] When in use in any one or more of a dry state, an equilibrium state, and at least one conditional state, the elongated tube and the sheath may be configured such that in at least one section through the medical gas conduit, the sheath is spaced outwardly from at least a portion of the periphery of the elongated tube.

[0044] The elongate tube and the jacket may be configured such that the elongate tube applies a hoop stress to the jacket when in use in at least one conditional state.

[0045] In use in at least one conditional state, the elongate tube and the sheath may be configured such that in at least one cross-section through the medical gas conduit, the sheath contacts the entire circumference of the elongate tube.

[0046] The breathable material may be unfoamed. Alternatively, the breathable material may be foamed.

[0047] The breathable material may include a block copolymer, preferably a block copolymer including one or more of: a hard segment of polybutylene terephthalate; and a soft segment of ether macroethylene glycol.

[0048] The block copolymer may comprise at least about 90%, preferably at least about 92%, more preferably at least about 95%, still more preferably at least about 97%, for example about 97% or about 98.5%, of the breathable material by one or more of mass, weight and volume.

[0049] The breathable material may include one or more additives, such as one or more of the following: a blowing agent, a colorant, an ultraviolet (UV) stabilizer, a UV absorber, and a processing aid. The one or more additives may include up to about 10%, preferably up to about 8%, more preferably up to about 5%, and most preferably up to about 3%, such as about 3% or about 2%, of the breathable material by one or more of mass, weight, and volume.

[0050] At least a portion of the elongated tube can be configured to absorb water molecules exceeding about 33% of its own dry mass during an immersion test, more preferably between about 33% and 200%, even more preferably between about 100% and 160%, even more preferably between about 120% and 140%, and most preferably between about 130% and 135%, for example about 133%.

[0051] At least a portion of the elongated tube can be configured to absorb between about 45% and 250% of its own dry mass in an immersion test, preferably between about 65% and 200%, more preferably between about 75% and 175%, even more preferably between about 100% and 160%, even more preferably between about 110% and 150%, even more preferably between about 120% and 140%, even more preferably between about 130% and 140%, and most preferably between about 133% and 139%, for example about 139%, of water molecules.

[0052] During an immersion test, when separated from the sheath, at least a portion of the elongated tube can be configured to expand during an immersion test in one or more of the radial direction, the longitudinal direction, and the wall thickness, and preferably in each of about 20% and 70%, preferably about 25% and 50%, and more preferably about 30% and 50%, for example about 32%.

[0053] During the immersion test, when separated from the sheath, at least a portion of the elongated tube can be configured to undergo one or more of the following conditions and preferably all of the following conditions: expansion in the radial direction by between about 37% and 47%, preferably about 42%; expansion in the longitudinal direction by between about 32% and 42%, preferably about 37%; and / or expansion in wall thickness by between about 29% and 39%, preferably about 34%.

[0054] The medical gas conduit may include a pair of connectors at opposite ends of the medical gas conduit, the pair of connectors being configured to pneumatically connect the elongated tube to other components of the medical gas system, at least one of the pair of connectors including a first connector component and a second connector component, wherein corresponding ends of the elongated tube and the sheath are fixed between the first connector component and the second connector component.

[0055] The first connector component may extend into the lumen of the elongate tube.

[0056] The second connector component may be overmoulded to one or more and preferably all of the first connector component, the elongate tube and the sheath.

[0057] The second connector part may comprise a plurality of apertures, preferably between two and six apertures, for example four apertures, through which the elongate tube and the sheath are exposed.

[0058] The end of the elongate tube may be disposed substantially concentrically around a portion of the first connector component; the end of the sheath may be disposed substantially concentrically around the end of the elongate tube; and the second connector component may be disposed substantially concentrically around the end of the sheath.

[0059] At least one of the first connector component and the second connector component may be at least partially formed from one or more of polycarbonate, polypropylene, and polyethylene.

[0060] At least one of the pair of connectors may be configured to prevent or inhibit expansion of an end portion of the elongate tube secured between the first connector component and the second connector component.

[0061] The elongated tube and the sheath may not be fixed to each other in the middle of a pair of connectors.

[0062] The catheter may be configured such that the elongate tube tapers towards at least one, and preferably both, of the pair of connectors when in use in at least one conditional state.

[0063] The catheter may be configured such that the sheath tapers toward at least one, and preferably both, of the pair of connectors in at least one, and preferably both, of the equilibrium state and the conditional state.

[0064] The medical gas conduit may be configured such that, in use: upon initial absorption of water molecules, the elongated tube is configured to expand relatively unconstrained by the sheath; and upon further absorption of water molecules, the elongated tube is configured to expand relatively constrained by the sheath.

[0065] The elongated tube may be configured to expand after prolonged use while relatively constrained by the sheath.

[0066] The sheath may be configured to: not constrain expansion of the elongate tube when the elongate tube is in a balanced state in use; and to constrain expansion of the elongate tube when the elongate tube is in at least one conditional state in use.

[0067] The medical gas conduit can be configured such that in use: upon initial absorption of water molecules, the elongated tube is configured to expand in the radial direction while being relatively unconstrained by the sheath; and upon further absorption of water molecules, the elongated tube is configured to further expand in the radial direction while being relatively constrained by the sheath.

[0068] The sheath may be configured to: not constrain expansion of the elongated tube in a radial direction when the elongated tube is in an equilibrium state; and to constrain expansion of the elongated tube in a radial direction when the elongated tube is in at least one conditional state in use.

[0069] The medical gas conduit can be configured such that in use: upon initial absorption of water molecules, the elongated tube is configured to expand in the longitudinal direction while being relatively unconstrained by the sheath; and upon further absorption of water molecules, the elongated tube is configured to expand in the longitudinal direction while being relatively constrained by the sheath.

[0070] The medical gas conduit may be configured such that upon further absorption of water molecules in use, the elongate tube is configured to expand in a radial direction and the sheath is configured to at least partially collapse the medical gas conduit in a longitudinal direction.

[0071] The sheath may be configured to not constrain expansion of the elongated tube in the longitudinal direction in a balanced state, and to constrain expansion of the elongated tube in the longitudinal direction in at least one conditional state.

[0072] The medical gas conduit can be configured such that, in use: upon initial absorption of water molecules, the elongated tube is configured to expand freely in radial and longitudinal directions; and upon further absorption of water molecules, the elongated tube is configured to engage the sheath, and further expansion is constrained in at least one of the radial and longitudinal directions.

[0073] The sheath may be configured to allow the elongated tube to freely expand in radial and longitudinal directions in a balanced state, and to restrict expansion of the elongated tube in at least one of the radial and longitudinal directions in at least one conditional state.

[0074] The medical gas conduit can be configured such that, in use: upon initial absorption of water molecules, the elongated tube is configured to expand freely in the radial direction to engage the inner surface of the sheath; and upon further absorption of water molecules, the elongated tube is configured to further expand in the radial direction, thereby causing the sheath to expand in the radial direction and contract in the longitudinal direction.

[0075] The elongated tube and the sheath may be configured such that expansion of the elongated tube in a radial direction causes the elongated tube to engage the sheath and causes the sheath to expand in the radial direction and contract in the longitudinal direction.

[0076] The elongated tube may be configured to have: a first length before use; a second length when initially absorbing water molecules; and a third length when further absorbing water molecules, wherein the second length is longer than the first length and the third length.

[0077] The elongated tube can be configured to have a first length in a balanced state; a second length in at least one conditional state, in which the radial expansion of the elongated tube is not constrained by the sheath; and a third length in at least one other conditional state, in which the radial expansion of the elongated tube is constrained by the sheath, wherein the second length is longer than the first length and the third length.

[0078] The third length may be within about 90% to 110% of the first length, and is preferably about equal to the first length.

[0079] The elongated tube may include a plurality of corrugations.

[0080] The medical gas conduit may be configured such that, in use, the profile of each corrugation of the plurality of corrugations changes as the elongate tube expands due to absorption of water molecules.

[0081] The plurality of corrugations may each be defined in part by a pair of side walls, and the elongate tube and jacket may be configured such that the side walls reorient, preferably towards a radial direction, in use when the elongate tube absorbs water molecules.

[0082] The side walls may be configured to redirect beyond a radial direction as the elongated tube continues to absorb water molecules.

[0083] The medical gas conduit can be configured such that: when the elongated tube is in at least one of a dry state and an equilibrium state, the spacing of the multiple corrugations is substantially uniform along the length of the elongated tube; and when the elongated tube is in at least one conditional state, the spacing of the multiple corrugations varies along the length of the elongated tube.

[0084] The elongated tube may include a sleeve portion at an end of the elongated tube, wherein the sleeve portion is non-corrugated.

[0085] The sheath may comprise a tubular mesh, preferably a braided tubular mesh.

[0086] The sheath may include a biaxial braid of a plurality of braid elements, each braid element extending helically around the elongate tube.

[0087] The plurality of knit elements may each include two or three filaments.

[0088] The sheath may include at least one of: between about 75 and 125 braided elements, preferably between about 90 and 100 braided elements, for example about 96 braided elements; and between about 150 and 250 filaments, and preferably between about 180 and 200 filaments, for example about 192 filaments.

[0089] The elongate tube may be configured to have a substantially uniform diameter in at least one of a dry state and an equilibrium state, and to have a substantially non-uniform diameter in at least one conditional state in use.

[0090] The medical gas conduit may be configured such that in use, in at least one conditional state, the elongate tube has a localised expansion in one or more regions where the relative humidity or volume of condensate within the lumen is elevated.

[0091] The medical gas conduit may be an expiratory conduit configured such that, in a constrained state during use, the elongated tube has a localized expansion in one or more of: an inlet region, which is closest to the patient interface of the medical gas system and includes up to about 50%, preferably up to about 33%, more preferably up to about 25%, even more preferably up to about 20%, and most preferably up to about 10% of the length of the elongated tube; an outlet region, which is closest to the gas return inlet of the gas source of the medical gas system and includes up to about 50%, preferably up to about 33%, more preferably up to about 25%, even more preferably up to about 20%, and most preferably up to about 10% of the length of the elongated tube; and an intermediate region, intermediate the inlet region and the outlet region and including up to about 50%, preferably up to about 33%, more preferably up to about 25%, even more preferably up to about 20%, and most preferably up to about 10% of the length of the elongated tube.

[0092] The breathable material may include a minimum melting point in a differential scanning calorimetry (DSC) test at a temperature greater than about 37°C, preferably greater than about 42°C, more preferably greater than about 44°C, more preferably greater than about 45°C, and most preferably greater than about 46°C, for example at a temperature of about 47°C.

[0093] The breathable material may include a minimum melting point in a DSC test at a temperature between about 37°C and 100°C, preferably between about 40°C and 60°C, and more preferably between about 40°C and 50°C, such as at a temperature of about 47°C.

[0094] The breathable material may include a melting point in a differential scanning calorimetry (DSC) test, the melting point being at a temperature between about 42°C and 52°C, preferably between about 44°C and 50°C, more preferably between about 45°C and 49°C, and still more preferably between about 46°C and 47°C, for example at a temperature of about 47°C.

[0095] The breathable material may include two melting points in a differential scanning calorimetry (DSC) test, with the temperatures of the two melting points being above about 197°C, preferably above about 202°C, more preferably above about 204°C, even more preferably above about 205°C, and most preferably above about 206°C, for example at or above about 207°C.

[0096] The breathable material may include two melting points in a differential scanning calorimetry (DSC) test, with the temperatures of the two melting points being between about 202°C and 225°C, preferably between about 204°C and 223°C, more preferably between about 205°C and 222°C, and even more preferably between about 206°C and 221°C, for example at temperatures of about 207°C and 220°C.

[0097] The breathable material may include two melting points in a differential scanning calorimetry (DSC) test, with the temperature difference between the two melting points being less than about 23°C, preferably less than about 18°C, more preferably less than about 16°C, still more preferably less than about 15°C, and most preferably less than about 14°C, for example, the temperature difference is about 13°C.

[0098] The breathable material may include two melting points in a differential scanning calorimetry (DSC) test, with the temperature difference between the two melting points being between about 150°C and 170°C, preferably between about 155°C and 165°C, more preferably between about 158°C and 162°C, and even more preferably between about 159°C and 161°C, for example, the temperature difference is about 160°C.

[0099] The breathable material may include three melting points in a differential scanning calorimetry (DSC) test, with the temperatures of the three melting points being between about 42°C and 225°C, more preferably between about 44°C and 223°C, still more preferably between about 45°C and 222°C, and most preferably between about 46°C and 221°C.

[0100] The breathable material may include one or more melting points in a differential scanning calorimetry (DSC) test, the temperature of the one or more melting points being at least one of the following and preferably all three: between about 42°C and 52°C, preferably between about 44°C and 50°C, more preferably between about 45°C and 49°C, and even more preferably between about 46°C and 47°C, for example, at a temperature of about 47°C; between about 202°C and 212°C, preferably between about 204°C and 210°C, more preferably between about 205°C and 209°C, and even more preferably between about 206°C and 208°C, for example, at a temperature of about 207°C; and between about 215°C and 225°C, preferably between about 217°C and 223°C, more preferably between about 218°C and 222°C, and even more preferably between about 219°C and 221°C, for example, at a temperature of about 220°C.

[0101] The medical gas conduit may be configured to have a compliance of less than about 4 ml / cmH2O, preferably less than about 2.5 ml / cmH2O, and more preferably less than about 1.2 ml / cmH2O in at least one conditional state.

[0102] When separated from the sheath, the elongated tube can be configured to have a compliance of greater than about 4 ml / cmH2O, preferably greater than 5 ml / cmH2O, in at least one conditional state.

[0103] The medical gas conduit can be configured to have the following flow resistance under at least one conditional state: less than about 0.06 cmH2O / l / min at a flow rate of 30 l / min; less than about 0.12 cmH2O / l / min at a flow rate of 15 l / min; or less than about 0.74 cmH2O / l / min at a flow rate of 2.5 l / min.

[0104] The medical gas conduit may be configured to increase resistance to flow with bending in at least one conditional state by less than 150%, less than 125%, or less than 115%, such as about 113%.

[0105] The medical gas conduit is configured to comply with any one or more, and preferably all, of the length, leakage, flow resistance and compliance requirements of International Standard 5367:2014(E) of the International Standards Organization (ISO) in at least one conditional state.

[0106] The medical gas catheter may be configured to have a compliance of less than about 4 ml / cmH2O, preferably less than about 2.5 ml / cmH2O, and more preferably less than about 1.2 ml / cmH2O after prolonged use.

[0107] When separated from the sheath, the elongated tube may be configured to have a compliance of greater than about 4 ml / cmH2O, preferably greater than 5 ml / cmH2O after prolonged use.

[0108] The medical gas conduit can be configured to have the following flow resistance after long-term use: less than about 0.06 cmH2O / l / min at a flow rate of 30 l / min; less than about 0.12 cmH2O / l / min at a flow rate of 15 l / min; or less than about 0.74 cmH2O / l / min at a flow rate of 2.5 l / min.

[0109] The medical gas conduit may be configured to increase resistance to flow by less than 150% with bending after prolonged use.

[0110] The medical gas conduit may be configured to comply with any one or more, and preferably all, of the length, leakage, flow resistance, and compliance requirements of International Standard 5367:2014(E) of the International Standards Organization (ISO) after prolonged use.

[0111] The elongate tube and sheath may be flexible to reduce tube drag on one or more of the Y-piece and patient interface of the medical gas system in use.

[0112] When separated from the sheath, the elongated tube may be more flexible in a conditioned state than in an equilibrium state.

[0113] The medical gas conduit may include an expiratory conduit, the medical gas system includes a respiratory assistance system, and the medical gas flow includes a respiratory gas flow, wherein the expiratory conduit may be configured to form more than about 80% of the total length of the expiratory limb of the respiratory assistance system when in use, preferably more than about 90%, and more preferably more than about 95%.

[0114] In the equilibrium state, the medical gas conduit or elongated tube may have the following length: between about 0.8m and 1.2m, for example about 1.0m; between about 1.0m and 2.5m, and preferably between about 1.1m and 1.4m, and more preferably between about 1.2m and 1.3m, for example about 1.25m; between about 1.4m and 1.6m, for example about 1.5m; between about 1.5m and 1.7m, for example about 1.6m; or between about 1.5m and 1.8m, for example about 1.6m or about 1.8m; or between about 2.2m and 2.6m, more preferably between about 2.3m and 2.5m, for example about 2.4m.

[0115] In the equilibrium state, the length measured by the medical gas conduit can be between about 1.1m and 1.8m, preferably between about 1.2m and 1.8m, more preferably between about 1.2m and 1.3m, or between about 1.4m and 1.6m, or between about 1.5m and 1.7m, for example about 1.2m or 1.5m or 1.6m.

[0116] In the dry state, the wall thickness of the elongated tube can be between about 0.5 mm and 0.9 mm, preferably between about 0.6 mm and 0.8 mm, more preferably between about 0.65 mm and 0.75 mm, still more preferably between about 0.68 mm and 0.72 mm, and most preferably between about 0.69 mm and 0.71 mm, for example about 0.70 mm.

[0117] When separated from the sheath and in a saturated state, the wall thickness of the elongated tube can be between about 0.7 mm and 1.1 mm, preferably between about 0.8 mm and 1.0 mm, more preferably between about 0.85 mm and 0.95 mm, still more preferably between about 0.90 mm and 0.94 mm, and most preferably between about 0.91 mm and 0.93 mm, for example about 0.92 mm.

[0118] In the dry state, the maximum outer diameter of the elongated tube may be between about 20 mm and 26 mm, preferably between about 21 mm and 25 mm, and more preferably between about 22 mm and 24 mm, such as about 23 mm.

[0119] When separated from the sheath and in a saturated state, the maximum outer diameter of the elongated tube may be between about 25 mm and 35 mm, preferably between about 28 mm and 32 mm, and more preferably between about 29 mm and 31 mm, for example about 30 mm.

[0120] The elongated tube may be extruded.

[0121] The elongated tube may be corrugated.

[0122] The elongated tube may be corrugated and the sheath may be configured to be at least partially spaced apart from peaks of the corrugations of the elongated tube when the medical gas conduit is in an equilibrium state.

[0123] Medical gas tubing may not include reinforcing ridges or rods within the lumen.

[0124] The gas permeable material may be configured to, in use, at least partially dry the flow of medicinal gas as it passes along the length of the lumen.

[0125] The at least one conditional state may include a simulated conditional state.

[0126] The medical gas system may include a Y-piece and a gas source, the medical gas conduit being configured to be directly coupled to each of: an outlet of the Y-piece; and a gas return inlet of the gas source or a filter directly coupled to the gas return inlet.

[0127] Medical gas tubing may not include water traps or may not be provided with water traps.

[0128] The medical gas conduit may be configured for use as or in an expiratory limb of a medical gas system, wherein the expiratory limb does not include a water trap.

[0129] Medical gas tubing may not include heating wires.

[0130] Other technical features may be readily apparent to those skilled in the art from the following drawings, descriptions and claims.

[0131] In a sixteenth aspect, a breathing circuit kit for use in a respiratory assistance system comprises: an inspiratory catheter; a Y-piece; and an expiratory catheter, at least one of the inspiratory catheter and the expiratory catheter comprising the medical gas catheter according to any one of the first to fifteenth aspects.

[0132] The breathing circuit kit may include a humidification chamber.

[0133] The breathing circuit kit may include any one or more of the following: a humidifier supply conduit; a patient interface; a filter; a pressure relief valve; a pressure regulator; and a conduit mount.

[0134] The breathing circuit kit may not include: a heating wire associated with the medical gas conduit; and / or a water trap associated with the medical gas conduit.

[0135] In a seventeenth aspect, an insufflation circuit kit comprises: an exhaust conduit, comprising the medical gas conduit of any one of the first to fifteenth aspects; and an exhaust filter.

[0136] The insufflator circuit kit may include any one or more of the following: an insufflator supply conduit; an adapter; a humidifier supply conduit; an insufflator gas filter; a humidification chamber; a funnel; a delivery conduit; a surgical cannula; a diffuser; and an additional exhaust conduit.

[0137] In the eighteenth aspect, a respiratory assistance system for providing respiratory therapy to a patient comprises: a gas source configured to supply a flow of respiratory gas; a humidifier configured to heat and humidify the flow of respiratory gas; a humidifier supply conduit configured to deliver the flow of respiratory gas from the outlet of the gas source to the inlet of the humidifier; an inspiratory conduit configured to deliver the flow of respiratory gas from the outlet of the humidifier to the inlet of the Y-piece or the patient joint for supply to the patient; and an expiratory conduit configured to deliver the flow of medical gas from the outlet of the Y-piece or the patient joint to the gas return inlet of the gas source or a filter at the gas return inlet; at least one of the inspiratory conduit and the expiratory conduit comprises the medical gas conduit described in any one of aspects one to fifteen.

[0138] The breathing assistance system may not include: a heating wire associated with the medical gas conduit; and / or a water trap associated with the medical gas conduit.

[0139] In a nineteenth aspect, a surgical insufflation system configured to supply an insufflation gas to a body cavity of a patient comprises: an insufflator configured to supply an insufflation gas flow; a humidifier configured to heat and humidify the insufflation gas flow; a humidifier supply conduit configured to deliver the insufflation gas flow from an outlet of the insufflator to an inlet of the humidifier; a delivery conduit configured to deliver the insufflation gas flow from the outlet of the humidifier to an inlet of a surgical cannula for supply to the body cavity of the patient; and an exhaust conduit configured to deliver the insufflation gas flow and surgical smoke away from the body cavity of the patient, the exhaust conduit comprising the medical gas conduit of any one of the first to fifteenth aspects.

[0140] In a twentieth aspect, a method of forming a conduit for delivering medical gas comprises: disposing a sheath around an elongated tube defining a lumen for flowing the medical gas therethrough; clamping a first end of the sheath to a first end of the elongated tube; and overmolding a connector to the first end of the sheath and the first end of the elongated tube to secure the connector, sheath, and elongated tube together.

[0141] The step of overmolding the connector may include inserting a first connector component at least partially into the lumen of the elongated tube wall at the first end of the elongated tube and overmolding a second connector component around the first connector component, the first end of the sheath and the first end of the elongated tube.

[0142] The method may comprise the step of injection moulding the first connector component prior to at least partially inserting the first connector component into the first end of the elongate tube.

[0143] The step of clamping the first end of the sheath to the first end of the elongated tube may include positioning the first end of the sheath and the first end of the elongated tube within a mold tool including a plurality of protrusions that engage and clamp the sheath to the elongated tube.

[0144] The plurality of protrusions may form a plurality of apertures in the connector when the connector is overmolded, wherein the boot is exposed through the plurality of apertures.

[0145] The method may include the steps of clamping the second end of the sheath to the second end of the elongated tube; and overmolding a second connector to the second end of the sheath and the second end of the elongated tube to secure the second connector, the second end of the sheath and the second end of the elongated tube together.

[0146] The method may comprise the step of, before clamping the second end of the sheath to the second end of the elongate tube, shrinking the sheath in a longitudinal direction such that the second end of the sheath covers the second end of the elongate tube.

[0147] The method may comprise the step of extruding an elongated tube.

[0148] The method may include the step of corrugating the elongate tube.

[0149] The method may include the step of cutting an elongate tube from the tubular extrusion.

[0150] The method may comprise the step of cutting the sheathing from a length of sheathing into predetermined sheath lengths, wherein the predetermined sheath lengths are selected such that when the sheath is arranged around the elongate tube and deformed to the length of the elongate tube, the sheath is at least partially spaced apart from the elongate tube in a radial direction.

[0151] The sheath may comprise a tubular mesh, preferably a braided tubular mesh.

[0152] The sheath may include at least one of the following: about 75 and 125 monofilament or multifilament braided elements, preferably about 90 and 100 braided elements, such as about 96 braided elements; and about 150 and 250 filaments, and preferably about 180 and 200 filaments, such as about 192 filaments. Alternatively, the sheath may include at least one of the following: about 40 and 60 monofilament or multifilament braided elements, preferably about 45 and 55 braided elements, such as about 48 braided elements; and about 120 and 180 filaments, and preferably about 135 and 165 filaments, such as about 144 filaments.

[0153] The elongated tube may comprise a gas permeable material, preferably a block copolymer, and more preferably a block copolymer comprising: a hard segment of polybutylene terephthalate; and a soft segment of ether macroethylene glycol.

[0154] The method may not include the step of providing the catheter with at least one, and preferably both, of a heating wire and a water trap.

[0155] In a twenty-first aspect, a catheter may be formed by the method of the twentieth aspect, wherein the elongated tube may be configured to expand upon absorbing water molecules, and the sheath is configured to selectively constrain expansion of the elongated tube during use.

[0156] In a twenty-second aspect, a catheter for a respiratory assistance system comprises: an elongated tube defining a lumen for allowing a breathing gas to flow through, the elongated tube comprising a material that is permeable to water molecules and expands due to absorbing water molecules; and a sheath disposed around the elongated tube; wherein the sheath is configured to constrain the expansion of the elongated tube in at least one of a radial direction and a longitudinal direction due to absorbing water molecules.

[0157] In a twenty-third aspect, a catheter for a respiratory assistance system comprises: a bellows defining a lumen for allowing a respiratory gas to flow through, the bellows comprising a plurality of corrugations and a material that is permeable to water molecules and expands due to the absorption of water molecules; and a sheath disposed around the bellows and configured to constrain the expansion of the bellows at least in the longitudinal direction of the bellows during use; wherein the bellows is configured such that the spacing between the plurality of corrugations changes during use depending on the absorption of water molecules by the bellows and the constraint of the bellows by the sheath.

[0158] In a twenty-fourth aspect, a catheter for a respiratory assistance system comprises: an elongated tube defining a lumen for allowing a breathing gas to flow through, the elongated tube comprising a material that is permeable to water molecules and expands due to absorbing water molecules; and a sheath arranged around the elongated tube, each end of the sheath being fixed to a corresponding end of the elongated tube, and the sheath being configured so that the length and diameter of the sheath vary in inverse proportion to each other.

[0159] In a twenty-fifth aspect, a catheter for a respiratory assistance system includes: an elongated tube defining a lumen for allowing a breathing gas to flow through; a sheath disposed around the elongated tube; and a pair of connectors for pneumatically connecting the elongated tube to other components of the respiratory system, each of the pair of connectors securing a respective end of the sheath to a respective end of the elongated tube, and at least the first connector of the pair of connectors including a plurality of orifices through which the elongated tube and the sheath are exposed.

[0160] In a twenty-sixth aspect, a catheter for a respiratory assistance system comprises: an elongated tube defining a lumen for passing a breathing gas flow, the elongated tube comprising a material permeable to water molecules, wherein the elongated tube is capable of absorbing more than about 33% of its own mass of water molecules in an immersion test, and the catheter does not include at least one of a heating wire and a water collector.

[0161] In a twenty-seventh aspect, a catheter for a respiratory assistance system comprises: an elongated tube defining a lumen for passing a breathing gas flow; and a sheath disposed around the elongated tube; wherein the sheath is configured to be at least partially spaced apart from the elongated tube in a radial direction.

[0162] In a twenty-eighth aspect, a catheter for use in a respiratory assistance system comprises: an elongated tube defining a lumen for allowing a breathing gas to flow through, the elongated tube comprising a material that is permeable to water molecules and expands when absorbing water molecules; and a sheath disposed around the elongated tube; wherein, at least under some operating conditions, the compliance of the catheter depends on the physical interaction between the elongated tube and the sheath.

[0163] In a twenty-ninth aspect, a catheter for use in a breathing assistance system comprises: an elongated tube defining a lumen for passing a breathing gas flow, the elongated tube comprising a material permeable to water molecules; and a pair of connectors at respective ends of the elongated tube for fluidically connecting the catheter fluid with other components of the breathing assistance system, at least one of the pair of connectors comprising a first connector component at least partially inserted into the lumen at one of the respective ends of the elongated tube, and a second connector component overmolded to the first connector component and the elongated tube.

[0164] In a thirtieth aspect, a respiratory assistance system includes: a gas source configured to generate pressurized respiratory gas; a humidifier configured to heat and humidify the pressurized respiratory gas; a main line conduit configured to transport the pressurized respiratory gas from the outlet of the gas source to the inlet of the humidifier; an inspiratory conduit configured to transport the pressurized respiratory gas from the outlet of the humidifier to the inlet of the Y-shaped piece for supply to a patient; and an expiratory conduit configured to transport the exhaled respiratory gas from the outlet of the Y-shaped piece to the gas return inlet of the gas source; wherein the expiratory conduit may include the conduit described in any one of aspects twenty-first to twenty-ninth.

[0165] In a thirty-first aspect, a method of forming a catheter for use in a respiratory assistance system includes: providing a sheath around an elongated tube, the elongated tube defining a lumen for allowing breathing gas to flow through; clamping a first end of the sheath to a first end of the elongated tube; and overmolding a connector to the first end of the sheath and the first end of the elongated tube to secure the connector, sheath and elongated tube together.

[0166] In a thirty-second aspect, a catheter may be formed by the method of the thirty-first aspect, wherein the elongated tube is configured to expand upon absorbing water molecules, and the sheath is configured to selectively constrain expansion of the elongated tube.

[0167] Other aspects and technical features may be readily apparent to one skilled in the art from the following drawings, description and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0168] To easily identify the discussion of any particular element or act, the most significant digit(s) in a reference number refers to the figure number in which the element is first introduced. Similar reference numerals are used in different figures and with reference to different examples to refer to similar features.

[0169] Examples are described in further detail below with reference to the accompanying drawings, in which:

[0170] Figure 1 is a schematic diagram of a respiratory assistance system according to the present disclosure, which may include a catheter.

[0171] Figure 2 is a schematic diagram of an alternative respiratory assistance system according to the present disclosure, which may include a catheter.

[0172] Figure 3 It can be used for Figure 2 Detailed diagram of an example humidifier in a respiratory assistance system.

[0173] Figure 4 is a schematic diagram of a bubble CPAP system according to the present disclosure, which may include a catheter.

[0174] Figure 5 is a schematic diagram of an alternative bubble CPAP system according to the present disclosure, which may include a catheter.

[0175] Figure 6 is a schematic diagram of a surgical insufflation system according to the present disclosure, which may include a catheter.

[0176] Figure 7 is a schematic diagram of a partial cutaway of an example catheter according to the present disclosure.

[0177] Figure 8 is a schematic isometric detail illustration of one end of an example catheter according to the present disclosure.

[0178] Fig. 9 is a schematic side detail illustration of one end of an example catheter according to the present disclosure.

[0179] Fig.10 is a schematic exploded side detail illustration of one end of an example catheter according to the present disclosure.

[0180] Fig.11 is a schematic cross-sectional side detail illustration of one end of an example catheter according to the present disclosure.

[0181] Fig.12 is a schematic exploded isometric detailed illustration of one end of an example catheter according to the present disclosure.

[0182] Fig.13 is a schematic isometric detailed illustration of an elongated tube and sheath of an example catheter according to the present disclosure.

[0183] Fig.14 is a schematic side detail view of an elongated tube and sheath of an example catheter according to the present disclosure.

[0184] Fig.15 is a schematic end cross-sectional view of an elongated tube and sheath of an example catheter according to the present disclosure.

[0185] Fig.16 is a schematic cross-sectional side detail illustration of an elongated tube and sheath of an example catheter according to the present disclosure.

[0186] Fig.17 is a graph of differential scanning calorimetry (DSC) test results for catheter breathable materials according to the present disclosure.

[0187] Fig.18 is a schematic detailed illustration of a sheath of an example catheter according to the present disclosure, wherein the catheter is in an equilibrium state.

[0188] Fig.19 yes Fig.18Schematic detailed view of the sheath with the catheter in a conditioned state.

[0189] Fig. 20 is a graph of length versus diameter gradients for a series of braided tubular mesh sheaths that may be used in catheters according to the present disclosure.

[0190] Fig.21 Schematic diagram showing the case without sheath (in Fig.21 (a) to Fig.21 (d)) and in the case of a sheath (in Fig.21 (e) to Fig.21 (h)) Change in state of the elongated tube of the example catheter according to the present disclosure due to absorption and pressurization of water molecules.

[0191] Fig. 22 is a schematic cross-sectional detail illustration of a corrugation profile of an example conduit in an equilibrium state according to the present disclosure.

[0192] Fig.23 is under conditional Fig. 22 Schematic cross-sectional detail of a catheter.

[0193] Fig.24 is a schematic cross-sectional detail illustration of a portion of an elongated tube of an example catheter in an equilibrium state according to the present disclosure.

[0194] Fig.25 It is in a conditional state without sheath Fig.24 Detailed schematic cross-section of an elongated tube.

[0195] Fig.26 is in a conditional state when restrained by a sheath (not shown) Fig.24 and Fig.25 Detailed schematic cross-section of an elongated tube.

[0196] Fig. 27 is a schematic diagram of a respiratory assistance system including an expiratory conduit according to the present disclosure in use.

[0197] Fig.28 is a flow chart of an example method of manufacturing a catheter according to the present disclosure. DETAILED DESCRIPTION

[0198] System Overview

[0199] The present technology relates to medical gas catheters having particular applications in various medical gas systems (eg, respiratory assistance systems and surgical insufflation systems), some examples of which are described below.

[0200] Respiratory support system

[0201] refer to Figure 1 , a partial cutaway view of a first example respiratory assistance system 100 for providing non-invasive ventilation (NIV) therapy is shown. The respiratory assistance system 100 has a gas source 102, a humidifier supply conduit 104, a humidifier 106, an inspiratory conduit 108, a Y-piece 110, a patient interface 112, and an expiratory conduit 114.

[0202] In the illustrated example, gas source 102 may be a room bleed ventilator having a pressure generator 116 (e.g., a blower). Pressure generator 116 draws ambient air into gas source 102 through gas inlet 118 and pressurizes it above ambient pressure to produce a supply of breathing gas. The ambient air may be supplemented with other gases, such as supplemental oxygen (not shown).

[0203] The gas source 102 may have a gas source controller 120 that controls the operation of the pressure generator 116. The control may be based on input received from one or more of a user interface 122 and one or more sensors (not shown).

[0204] In other examples, gas source 102 may have a positive displacement pump (e.g., a bellows pump), or may receive breathing gas from a remote source (i.e., a non-room bleed ventilator). For example, gas source controller 120 may control the pressure of the breathing gas delivered to the patient by controlling a proportional solenoid valve.

[0205] Mechanical ventilation can vary from providing supplemental pressure and flow to assist a spontaneously breathing patient ("respiratory support") to complete control of each breath ("life support").

[0206] For an adult patient, the breathing gas may be delivered to the patient and returned to the gas source (e.g., a ventilator) at a flow rate of up to 120 liters per minute (l / min) (e.g., in the range of about 30 l / min to 80 l / min). The breathing gas may be delivered to the patient and returned to the gas source (e.g., a ventilator) at a pressure of up to about 6 kilopascals (kPa) (about 60 cmH2O).

[0207] For a neonatal or pediatric patient, the breathing gas may be delivered to the patient and returned to the gas source at a flow rate between about 0.5 l / min and 60 l / min. The exact flow rate may depend on the treatment and the patient's weight. The breathing gas may be delivered to the patient and returned to the gas source at a pressure of up to about 6 kPa (about 60 cmH2O).

[0208] Components of a breathing assistance system (e.g., a catheter) may be tested and marked for use at higher pressures, such as 8 kPa (approximately 80 cmH2O).

[0209] Patients receiving mechanical ventilation may be connected to the breathing assistance system for more than 24 hours, and depending on the patient's condition this connection may even last for months or be permanently connected.

[0210] In another example, the gas source 102 can be an anesthesia machine. For anesthesia applications, a breathing assistance system can deliver a mixture of breathing gas and anesthetic to the patient, for example, to sedate the patient and make him unconscious for surgery. The anesthetic gas mixture can be delivered to the patient at a flow rate of up to about 20l / min or up to about 10l / min for some "low flow" applications. The anesthetic gas mixture can be delivered at a pressure of up to about 6kPa. But the pressure is typically lower than the pressure of mechanical ventilation. The anesthesia machine can include a rebreathing system that delivers gas to the patient via an inspiratory conduit and returns the exhaled gas to the anesthesia machine via an expiratory conduit. The anesthesia machine and the breathing circuit usually form a closed loop to prevent anesthetics from leaking into the surrounding environment. The patient will usually not need to be connected to the anesthesia machine for more than 24 hours. Most patients who receive anesthetics will be connected to the breathing circuit for far less than 24 hours. The patient who receives anesthetics can be continuously monitored by an anesthesiologist during the duration of anesthesia.

[0211] Gas source 102 supplies breathing gas to humidifier 106 via gas source outlet 124 and humidifier supply conduit 104. In the illustrated example, humidifier 106 can be an active (heated) sweep-type humidifier. Humidification chamber 126 can be located on top of chamber heater 128, or otherwise in thermal contact with chamber heater 128. Humidification chamber 126 can be removably coupled to chamber heater 128. A volume of water within humidification chamber 126 is heated to vaporize water into the headspace of humidification chamber 126. Breathing gas is received from humidifier supply conduit 104 at the inlet of humidification chamber 126. Breathing gas can pass through the headspace of humidification chamber 126, absorb water vapor, and reach the outlet of humidification chamber 126.

[0212] Chamber heater 128 may be controlled by humidifier controller 130 based on input from one or more of user interface 132 and one or more sensors to achieve a desired level of one or more of heating and humidification of the breathing gases.

[0213] In some examples, the humidification chamber 126 may have a float valve (not shown) to automatically refill the water reservoir from a sterile water bag (not shown). For example, the humidifier 106 may be the F&P 810 available from Fisher & Paykel Healthcare Limited of Auckland, New Zealand. TM ,820 TM , 850 TM or 950 TMHeated Humidifier. The humidification chamber 126 may include a water supply tube and a water spike (not shown) for fluid connection with a sterile water bag.

[0214] A humidifier controller 130 of humidifier 106 may control the temperature of chamber heater 128. Chamber heater 128 may be controlled so that humidified breathing gases are received by the patient at or near a predetermined temperature and humidity. In the case where the patient receives invasive ventilation, the patient's upper airway is bypassed, and the breathing gases may be delivered to the patient at a temperature of approximately 37° C. and a relative humidity of approximately 100%. In the case where the patient receives non-invasive ventilation, the breathing gases may be delivered to the patient's upper airway at a temperature of approximately 31° C. and a relative humidity of 70%. The breathing gases may be further heated and humidified by the patient's upper airway to reach the patient's lungs at a temperature of approximately 37° C. and a relative humidity of approximately 100%.

[0215] One or more of the desired temperature and humidity of the breathing gas may be adjustable using user interface 132. Alternatively or additionally, humidifier 106 and gas source 102 may be in electronic communication with each other, whereby settings of humidifier 106 may be observed and / or adjusted from gas source 102, or vice versa. Humidifier controller 130 may receive signals from one or more sensors to provide open-loop or closed-loop control of one or more of the temperature and humidity of the breathing gas.

[0216] In other examples, the humidifier 106 can be a passive (non-heated) passover type humidifier, a heat and moisture exchanger (HME), a misting humidifier, or a humidifier that supplies a continuous or periodically controlled flow of humidified liquid to a heating element for instantaneous or near-instantaneous vaporization.

[0217] Figure 1 The respiratory assistance system 100 of the present invention shows the gas source 102 and the humidifier 106 as separate devices. In other examples, the gas source 102 and the humidifier 106 can be integrally formed with each other. In such examples, the humidifier supply conduit 104 can be or include an internal conduit within the housing of the integrally formed device. The functions of the gas source controller 120 and the humidifier controller 130 can be performed by a single controller or a decentralized control system. Similarly, the user interface 122 and the user interface 132 can be replaced by a single user interface that can receive inputs for controlling both the pressure generator 116 and the chamber heater 128.

[0218] Still reference Figure 1In an example respiratory assistance system 100, breathing gases are delivered from a humidifier 106 toward a patient through a flexible inspiratory conduit 108. In some examples, the inspiratory conduit 108 can have a length of about 1.0 meters (m) to about 2.5 meters. In some examples, the inspiratory conduit 108 can have a length of about 1.5 meters to 1.8 meters, such as about 1.6 meters or 1.8 meters. In some examples, such as for anesthesia applications, the inspiratory conduit 108 can have a length of about 2.2 meters to 2.6 meters, such as about 2.4 meters.

[0219] The suction conduit 108 can be corrugated. In some examples, for example, for adult patients, the maximum outer diameter of the corrugated suction conduit 108 (i.e., the diameter of the suction conduit 108 when the outer surface is measured at the peak of the corrugation) can be about 20 millimeters (mm) to 30 mm, or about 23 mm to 25 mm, for example, about 24 mm. In other examples, for example, for neonates or pediatric patients, the maximum outer diameter can be about 10 mm to 20 mm, or about 14 mm to 16 mm, for example, about 15 mm. The suction conduit 108 can also have a corrugated inner surface. In other examples, the suction conduit 108 can have a substantially smooth (e.g., non-corrugated) inner surface.

[0220] Inspiratory conduit 108 may have a heating wire 134 (only partially shown for clarity). For example, heating wire 134 may be wrapped around the outside of the tube wall, embedded within the tube wall, or located in the lumen of inspiratory conduit 108. Heating wire 134 may be powered by humidifier 106. Heating wire 134 may be controlled by humidifier controller 130 to mitigate heat loss of the respiratory gases as they pass along the length of inspiratory conduit 108. In some examples, heating wire 134 may maintain or, in some cases, increase the temperature of the respiratory gases as they pass along the length of inspiratory conduit 108.

[0221] In some examples, the suction catheter 108 can have a composite structure consisting of two or more components wound around the lumen in a spiral manner. The first spirally wound component can be an elongated hollow body, and the second spirally wound component can be an elongated structural component. The first and second spirally wound components can be wound in a double helix configuration. The heating and / or sensing wires can be embedded in the elongated structural component. The suction catheter 108 can have a connector with a printed circuit board (PCB). The heating and / or sensing wires can be connected to the PCB. Further design and manufacturing details of such catheters are disclosed in U.S. Patent Publication Nos. 2015 / 0306333, 2017 / 0100556, 2019 / 0076620 and 2022 / 0355059, all of which are assigned to Fisher & Paykel Healthcare Ltd, and the entire contents of each of which are incorporated herein by reference.

[0222] The sensor probe 136 can be removably inserted into the orifices at the patient end and the humidifier end of the inspiratory catheter 108. For example, the sensor probe 136 may include one or more of a temperature sensor, a humidity sensor, and a flow sensor. The sensor lead 138 can connect the sensor probe 136 to the humidifier 106 so that the signal from the sensor probe 136 can be used as an input in the control algorithm for one or more of the pressure generator 116, the chamber heater 128, and the heating wire 134. In other examples, the sensor can be integrally formed in one or more of the humidifier 106 and the inspiratory catheter 108. In some examples, one or more of the sensor leads 138 can be embedded in the tube wall or located in the lumen. In some examples, one or more sensors can be integrally formed in the inspiratory catheter 108.

[0223] The inspiratory conduit 108 can be provided with connectors at opposite ends to establish and maintain respective pneumatic connections with the outlet of the humidification chamber 126 and the inlet of the Y-piece 110. In some examples, such as for adult patients, the connectors can each be an adapter having a 22 mm tapered connector. The connector can have a 1:40 taper in accordance with the International Organization for Standardization (ISO) 5356-1:2015 (Anesthetic and Respiratory Equipment—Tapered Connectors—Part 1: Cones and Taper Sleeves). In other examples, such as for neonates or pediatric patients, the connector can be any of the following: a 15 mm tapered male tapered connector, a 15 mm tapered female tapered connector, a 12 mm tapered male tapered connector, a 12 mm tapered female tapered connector, and any combination thereof.

[0224] In some examples, the connector at the humidifier end of the inspiratory conduit 108 may have a socket for receiving the sensor probe 136. In some examples, the connector at the humidifier end of the inspiratory conduit 108 may have a socket for establishing an electrical connection between the humidifier 106 and the heater wire 134. In other examples, the humidifier 106 and the connector may have corresponding integrally formed electrical contacts, whereby when the inspiratory conduit 108 is physically connected to the humidifier 106, both the pneumatic connection and the electrical connection may be established in a single action.

[0225] Breathing gases are delivered by the inspiratory conduit 108 to a Y-piece 110 adjacent to or near the patient. The Y-piece 110 fluidly couples the inspiratory conduit 108 (via the inlet of the Y-piece), the patient interface 112 (via the patient inlet / outlet of the Y-piece), and the expiratory conduit 114 (via the outlet of the Y-piece). It will be appreciated that while the three branches of the Y-piece 110 (inlet, outlet, and patient inlet / outlet) form a Y shape in this example, the term is not intended to be limited to this particular configuration.

[0226] In some examples, an engagement conduit (not shown) may be provided between the patient inlet / outlet of the Y-piece 110 and the patient engagement portion 112 .

[0227] In other examples, the patient interface 112 may have an integrally formed Y-piece or separate inlets and outlets for respectively connecting the inspiratory conduit 108 and the expiratory conduit 114. In such examples, the separate Y-piece 110 may be omitted from the system.

[0228] In the illustrated example, the patient interface 112 is a nasal mask suitable for non-invasive ventilation by supplying humidified breathing gas to the nasal passages of the patient. In other examples, the patient interface 112 can be any invasive or non-invasive patient interface.

[0229] Examples of non-invasive patient joints include:

[0230] A full-face mask that seals around the patient's eyes, nose, and mouth;

[0231] Full face mask, which seals around the patient's nose and mouth;

[0232] A nasal mask, which seals around the patient's nose;

[0233] A compact nasal mask that seals to the underside of the patient's nose around the nostrils;

[0234] A nasal pillow joint that seals with each nostril of the patient;

[0235] Sealed nasal cannula, which seals inside each nostril of the patient;

[0236] Non-sealing nasal cannulas, which extend into the patient's nostrils without blocking the nasal passages;

[0237] A mask, which seals around the patient's mouth;

[0238] Hybrid masks that combine a compact nasal mask, nasal pillow interface or nasal cannula with a mouthpiece; and

[0239] A combination of the above (e.g., nasal cannula and full face mask).

[0240] Examples of invasive patient joints include:

[0241] Endotracheal tube, and

[0242] Tracheostomy tube.

[0243] Gases exhaled by the patient, as well as any excess breathing gas from gas source 102 that the patient did not inhale, are received from Y-piece 110 by expiratory conduit 114. Expiratory conduit 114 delivers the breathing gas to a gas return inlet 140 of gas source 102.

[0244] The expiratory conduit 114 can have connectors at opposite ends to establish and maintain respective pneumatic connections with the outlet of the Y-piece 110 and the gas source 102 (or an optional filter intermediate the expiratory conduit 114 and the gas return inlet 140). In some examples, such as for adult patients, the connectors can each be an adapter having a 22 mm tapered connector (e.g., a 22 mm tapered female connector). The connector can have a 1:40 taper in accordance with the ISO 5356-1:2015 standard. In other examples, such as for neonates or pediatric patients, the connector can be any of the following: a 15 mm tapered male connector, a 15 mm tapered female tapered connector, a 12 mm tapered male connector, a 12 mm tapered female tapered connector, and any combination of the two.

[0245] Because the patient's inspired and expired gases are humidified by the humidifier 106 and, for non-invasive ventilation, the patient's upper airway, the gases received by the expiratory conduit 114 may have a relative humidity of up to 100% (ie, saturated).

[0246] The expiratory conduit 114 does not necessarily have a heating wire. Advantages may be gained by omitting the heating wire from the expiratory conduit 114, as described in further detail below. However, in some examples, the expiratory conduit 114 may be provided with a heating wire. In such examples, the heating wire may be wrapped around the exterior of the tube wall, embedded in the tube wall, or located in the lumen of the expiratory conduit 114.

[0247] In this example, the expiratory conduit 114 also does not have or is not provided with a water trap.

[0248] In some examples, the expiratory conduit 114 can have a length of about 1.0m to 2.5m, or about 1.4m to 1.6m, for example, about 1.5m. In some examples, the expiratory conduit 114 can have a length of about 1.5m to 1.7m, for example, about 1.6m. In other examples, for example, for anesthesia applications, the expiratory conduit 114 can have a length of about 2.3m to 2.5m, for example, about 2.4m. In other examples, the expiratory conduit 114 can have a length of about 1.1m to 1.4m, or about 1.2m to 1.3m, for example, about 1.25m.

[0249] The expiratory conduit 114 can be corrugated. In some examples, such as for adult patients, the maximum outer diameter of the corrugated expiratory conduit 114 (i.e., the diameter of the expiratory conduit 114 when the outer surface is measured at the peak of the corrugation) can be about 20mm to 30mm, or about 23mm to 25mm, such as about 24mm. In other examples, such as for neonates or pediatric patients, the maximum outer diameter of the corrugated expiratory conduit 114 can be about 10mm to 20mm, or about 14mm to 16mm, such as about 15mm. The expiratory conduit 114 can have a corrugated inner surface. In other examples, the expiratory conduit 114 can have a substantially smooth (e.g., non-corrugated) inner surface.

[0250] In other examples, expiratory conduit 114 may be helically wound.

[0251] In some examples, one or more of the inspiratory conduit 108 and the expiratory conduit 114 may have an identification element. For example, the identification element may be a resistor, a capacitor, or an integrated circuit (IC). The identification element may enable one or more of the humidifier 106 and the gas source 102 to identify the conduit. In some examples, one or more of the humidifier 106 and the gas source 102 may automatically adjust one or more treatment parameters based on the identification of the conduit. In some examples, the identification element may enable the type (e.g., model) of the conduit to be identified. In some examples, the identification element may communicate with the humidifier 106 or the gas source 102 via a wired connection. In other examples, the identification element may be configured to communicate wirelessly, for example, using radio frequency identification (RFID).

[0252] A filter (not shown) may be disposed between the exhalation conduit 114 and the gas return inlet 140. In some examples, a filter may additionally or alternatively be disposed within the gas source 102.

[0253] The humidifier supply conduit 104, the humidification chamber 126, the inspiratory conduit 108, the Y-piece 110, and the expiratory conduit 114 together form a breathing circuit. More specifically, this particular configuration forms a double-limb breathing circuit 142.

[0254] The humidifier supply conduit 104, the humidification chamber 126 and the inspiratory conduit 108 form an inspiratory limb 144 of the breathing circuit 142. The inspiratory limb 144 extends from the outlet of the gas source 102 to the Y-piece 110.

[0255] In this example, expiratory conduit 114 forms an expiratory limb 146 of breathing circuit 142. Expiratory limb 146 extends from Y-piece 110 (or in some cases, directly from patient interface 112) to gas return inlet 140 of gas source 102 (or in some cases, a filter at gas return inlet 140).

[0256] The Y-piece 110 may be considered a portion of either or both of the inspiratory limb 144 and the expiratory limb 146 .

[0257] In some examples, such as Figure 1 As shown in , expiratory conduit 114 can form the entire expiratory limb 146 (excluding Y-piece 110). In other examples, the expiratory limb can also include one or more of a filter and a second expiratory conduit that is connected end-to-end to expiratory conduit 114. In some examples, expiratory conduit 114 can form substantially most of the length of expiratory limb 146, such as more than about 80%, more than about 90%, or more than about 95%.

[0258] Expiratory conduit 114 may define the entire flow path from Y-piece 110 (or in some cases, patient interface 112) to gas return inlet 140 (or in some cases, an optional filter) of gas source 102. That is, no additional conduit may be required in the expiratory limb of the breathing circuit.

[0259] The entire expiratory conduit 114 will generally be exposed to the ambient air of the surrounding environment (eg, a hospital room), except perhaps for portions of the expiratory conduit 114 that are inadvertently or temporarily covered by a patient's limbs, clothing, bedding, etc. during use.

[0260] The technology of the present disclosure is particularly suitable for use as an expiratory conduit 114 of a respiratory assistance system 100 .

[0261] In some examples, the techniques of this disclosure may alternatively or additionally be adapted for use as inspiratory catheter 108. In anesthesia procedures, for example, mitigating condensation within inspiratory catheter 108 may be a higher priority than maintaining 100% relative humidity of the respiratory gases delivered to the patient.

[0262] Figure 2 Another example respiratory assistance system 200 for providing NIV therapy is shown. Like the respiratory assistance system 100, the respiratory assistance system 200 has a gas source 102, a humidifier supply conduit 104, a humidifier 106, an inspiratory conduit 108, a Y-piece 110, a patient interface 112, and an expiratory conduit 114. The respiratory assistance system 200 is similar to the respiratory assistance system 100 except as described below or otherwise apparent from the drawings. Figure 1 The present invention relates to a breathing assistance system 100, and the description of the breathing assistance system 100 is intended to be equally applicable to the breathing assistance system 200.

[0263] In some examples, the heating wires 134, 202 may be provided in both the inspiratory conduit 108 and the expiratory conduit 114. However, in some examples, at least the heating wire 202 in the expiratory conduit 114 may be omitted.

[0264] For example, the heating wire 202 in the expiratory tube 114 can be wrapped around the outside of the tube wall, embedded in the tube wall, or located in the lumen of the expiratory tube 114.

[0265] Expiratory heater wire 202 may be powered by humidifier 106. Heating wire 202 may be controlled by humidifier controller 130 to mitigate heat loss of the respiratory gases as they pass along the length of expiratory conduit 114. In some examples, heating wire 202 may be controlled to increase, maintain, or in some cases, reduce the temperature of the respiratory gases as they pass along the length of expiratory conduit 114.

[0266] Sensors 204 (e.g., one or more of a temperature sensor, a humidity sensor, and a flow sensor) may be integrally formed within the inspiratory conduit 108, within a connector of the inspiratory conduit 108. One or more of the sensors 204 may be electrically connected to the humidifier 106 via sensor wires embedded within the wall of the conduit or disposed within the lumen of the inspiratory conduit 108.

[0267] The inspiratory conduit 108 may have an electropneumatic connector 206 having integrally formed electrical contacts. The electropneumatic connector 206 may be configured to establish both a pneumatic connection and an electrical connection with the humidifier 106 in a single action when the connector is physically connected to the humidifier 106. This may avoid the need for Figure 1 The need for a removable sensor probe 136 and sensor lead 138 of the breathing assistance system 100 shown in FIG.

[0268] The humidifier 106 may have a sensor probe 136 at or adjacent to the outlet of the humidification chamber 126 (at Figure 2 is hidden in the Figure 3 described in further detail.

[0269] In this example, the gas source 102 has a supplemental gas inlet 208 for providing supplemental gas (eg, supplemental oxygen) to the patient.

[0270] The technology of the present disclosure is particularly suitable for use as an expiratory conduit 114 of a respiratory assistance system 200. In some examples, such as for anesthesia procedures, it may alternatively or additionally be suitable for use as an inspiratory conduit 108.

[0271] Figure 3An example humidifier 106 is shown in detail that may be used in a breathing assistance system 200. A humidifier supply conduit 104 and an inspiratory conduit 108 are also (partially) shown.

[0272] Figure 3 The humidifier 106 depicted in FIG. 1 is a F&P 950 humidifier available from Fisher & Paykel Healthcare. TM Respiratory humidifier. The illustrated humidifier 106 has a heater base 302 and a removable and replaceable humidification chamber 126. The heater base 302 may have a chamber heater 128 (in Figure 3 ), a user interface 132, and a controller (not shown). The humidifier 106 may also have a removable and replaceable cartridge 304.

[0273] In this example, the user interface 132 may include a touch screen display 306 (i.e., for receiving input from a user and providing input to a user). The user interface 132 may also include one or more of a switch 308 and an indicator light 310. The switch 308 may be a mechanical (e.g., a push button or a toggle switch) or a touch-controlled electrical (e.g., capacitive) switch. The switch 308 may be a power / standby button. The indicator light 310 may be used to indicate when a fault condition occurs. The indicator light 310 may be a light emitting diode (LED). The indicator light 310 may be any suitable shape or form (e.g., a bar, a circle, a rectangle, a square, the perimeter of the touch screen display 306, etc.). The indicator light 310 may selectively light up in a single color (e.g., red, yellow, or green), or light up in two or more different colors (e.g., yellow and red) to indicate fault conditions of different priorities.

[0274] The humidification chamber 126 can be removably received by the heater base 302 and connected to the chamber heater 128 (in Figure 3 hidden under the humidification chamber 126) for thermal contact.

[0275] The box 304 can house electronic devices. The electronic devices can include one or more sensors. The sensors in the box 304 can sense one or more properties of the respiratory gas flowing through the humidification chamber 126 in use. The sensors can be set on one or more sensor probes 136 (hidden) protruding from the box. In use, the sensor probe 136 can protrude through an orifice in one or more of the inlet and outlet of the humidification chamber. The orifice can be closed by an elastomeric seal. When the humidification chamber 126 is received by the heater base 302, the elastomeric seal can be elastically deformed by the sensor probe 136.

[0276] The cartridge 304 may have an electrical connector that electrically connects to the heater base 302 for communication with the controller (eg, serial communication). The cartridge 304 may have a microcontroller that is communicatively coupled to the controller and the sensor(s).

[0277] In use, the outlet end of the humidifier supply conduit 104 is pneumatically coupled to the inlet of the humidification chamber 126. The electro-pneumatic connector 206 of the inspiratory conduit 108 is electrically coupled to the box 304 and pneumatically coupled to the outlet of the humidification chamber 126 to transport the humidified gas flow toward the patient. The electro-pneumatic connector 206 can be releasably and lockably connected to one or more of the humidification chamber 126 and the box 304. The electro-pneumatic connector 206 can have a release button 312. The release button 312 can be actuated to facilitate disconnection of the electro-pneumatic connector 206 from the humidifier 106.

[0278] The electro-pneumatic connector 206 can be configured so that it can be physically and pneumatically coupled with the humidification chamber 126 before the humidification chamber 126 is mounted on the heater base 302. The electro-pneumatic connector 206 can be configured so that it can be electrically connected with the humidifier 106 when the humidification chamber 126 is mounted on the heater base 302 in a sliding motion (e.g., in a horizontal direction).

[0279] Alternatively or additionally, the electro-pneumatic connector 206 can be configured such that it can be physically and pneumatically connected to the humidification chamber 126 when the humidification chamber is already mounted on the heater base 302, and physically and electrically connected to the humidifier 106 substantially simultaneously (e.g., in a single action).

[0280] In one example, the suction conduit 108 can have a substantially smooth inner surface. The suction conduit 108 can have a lower resistance to flow than an equivalent bellows, and accordingly can have a relatively small inner diameter (when compared to the minimum inner diameter of the bellows). For example, in this example, the suction conduit 108 can have a substantially uniform inner diameter of about 15 mm to 19 mm, such as about 17 mm, for adult patients or about 10 mm to 14 mm, such as about 12 mm, for neonates or pediatric patients. In some examples, the suction conduit 108 can be spirally wound.

[0281] The electro-pneumatic connector 206 may have a pair of sensor wires and a pair of heating wires 134 (in Figure 3 At least one of the sensor wires and the heating wire 134 may be embedded in the wall of the inhalation conduit 108. The sensor wire and the heating wire 134 may form a corresponding sensing and heating loop.

[0282] The electro-pneumatic connector 206 may have electrical terminals electrically coupled to an identification element (e.g., a resistor) embedded within the electro-pneumatic connector 206. A controller of the humidifier 106 may be configured to identify the type of inspiratory catheter 108 coupled to the humidifier 106, such as by applying a voltage across the corresponding electrical terminals and measuring a current through the resistor. A resistance of, for example, about 100 ohms (Ω) may indicate to the controller that a first type of inspiratory catheter 108 (e.g., an adult catheter) is coupled to the humidifier 106, and a resistance of, for example, about 200 Ω may indicate to the controller that a second type of inspiratory catheter 108 (e.g., a neonatal catheter) is coupled to the humidifier 106.

[0283] In other examples, the electro-pneumatic connector 206 may have an identification element that includes an IC having a non-transitory memory configured to store identification data, as described above.

[0284] The electrical terminals of the electro-pneumatic connector 206 can be configured to electrically connect with corresponding terminals on the cartridge 304. Thus, an existing heater base 302 can be retrofitted with a replacement cartridge 304 that can include one or more of the additional electronics and electrical terminals to provide new functionality to the humidifier 106. Similarly, the humidifier 106 can be retrofitted with a replacement cartridge 304 to be compatible with alternative inspiratory catheters, if necessary. Alternatively, the electrical terminals of the electro-pneumatic connector 206 and cartridge 304 can be arranged so that selected "core" terminals are electrically connected with corresponding terminals of two or more different cartridges, while "optional" terminals or pads are electrically connected only with specific terminals or pads of a selected cartridge that are configured to utilize those connections.

[0285] At the distal end (i.e., the patient end) of the inspiratory catheter 108, Figure 3 At the distal end of the tube (not shown), a sensor (e.g., a temperature sensor) can be electrically coupled to the pair of sensing wires to form a sensing circuit. The heating wires can be electrically coupled to each other to form a heating loop. If desired, additional wire(s) or conductor(s) can be similarly electrically coupled to the distal end of the tube.

[0286] The humidifier 106 (e.g., the box 304) can have a socket or an integrally formed cable configured for connection to the expiratory conduit 114, for example, to supply power to the optional expiratory heater wire 202 (at Figure 3 not shown).

[0287] refer to Figure 4 , shows a further example breathing assistance system 400, this time in the form of a bubble CPAP system providing bubble CPAP (continuous positive airway pressure) therapy.

[0288] Except as described below and shown in the accompanying drawings, Figure 4 The breathing assistance system 400 may accordingly be similar to Figure 1 Respiratory assistance system 100 and Figure 2 Respiratory assistance system 200.

[0289] The gas supplied to the patient may be ambient air, oxygen, a mixture of the two, or a mixture of ambient air and (multiple) other auxiliary gases. These gases may include medicaments. These medicaments may be added by atomization. In this example, the gas source 102 may be or include a wall-mounted source, such as in a hospital. The gas flow delivered to the patient in the respiratory assistance system 400 may be delivered at a substantially constant flow rate.

[0290] For a neonatal or pediatric patient, the breathing gas in the bubble CPAP system can be delivered to the patient at a flow rate of about 2 liters per kilogram per minute (L / kg / min). In some examples, the flow rate can be between about 1 l / min and 15 l / min, between about 4 l / min and 15 l / min, or between about 6 l / min and 8 l / min. The breathing gas can be delivered to the patient at a pressure between about 3 cmH2O and 10 cmH2O.

[0291] The breathing assistance system 400 may have a pressure regulator 402. In the illustrated example, the pressure regulator 402 is in the form of a bubbler.

[0292] The bubbler can be configured to hold a volume of liquid 404 (e.g., water). The bubbler can have an adjustable inlet probe 406 that is configured to extend into the bubbler to be immersed in the liquid 404. The inlet probe 406 can be configured to be pneumatically coupled to the expiratory conduit 114. The bubbler can act as a pressure regulator by exhausting gas from the respiratory assistance system 400 when the pressure exceeds a desired level. This can maintain the average pressure or equalized pressure at a target level. The target pressure level can be adjusted by immersing the inlet probe 406 to a desired depth in the liquid 404.

[0293] A potential problem with condensation in the breathing circuit of a bubble CPAP system is that at least some of the condensation may flow into the bubbler. This may increase the volume of liquid 404 in the bubbler, thereby increasing the depth of the inlet probe 406. This in turn may increase the positive end-expiratory pressure (PEEP) above the target level during use.

[0294] During use, gas escapes from the terminal end of the inlet probe 406 and bubbles to the surface of the liquid 404. This bubbling may cause small fluctuations in gas pressure. These fluctuations may have therapeutic effects on the patient.

[0295] The breathing assistance system 400 may have a pressure relief valve 408 for venting excess gas when the pressure exceeds a selected level.

[0296] The example breathing assistance system 400 provides another example of a dual-limb breathing circuit 142. The term "circuit" is not intended to require that the breathing circuit must necessarily form a closed loop, although it can do so in at least some examples. The inspiratory limb 144 can also include an optional pressure relief valve 408. The expiratory limb 146 can also include a pressure regulator 402.

[0297] refer to Figure 5 , shows another example of a breathing assistance system 500, which is again in the form of a bubble CPAP system. In addition to the contents described below, Figure 5 The breathing assistance system 500 may be similar to Figure 4 Respiratory assistance system 400.

[0298] In this example, the gas source 102 includes a flow generator (e.g., a blower 502). The blower 502 may include an electric motor that drives an impeller to pressurize ambient air to produce a supply of breathing gas. Using a flow generator to generate a gas flow can allow the breathing assistance system 500 to provide bubble CPAP therapy without the need for a wall-mounted source. The gas source 102 may include a battery power source for the blower 502. The battery power source can allow the breathing assistance system 500 to provide therapy at least temporarily without connecting the gas source 102 to an electrical outlet with a power cable (e.g., when a patient is moved between hospital rooms).

[0299] The flow generator can draw ambient air for supply to the patient. The respiratory assistance system 500 can be simpler and cheaper to use because no gas reservoir or gas source (e.g., wall-mounted source) is required. Using a flow generator to pressurize sufficient ambient air can eliminate the risk of exhaust gas supply. Exhaust gas supply may interrupt treatment of the patient.

[0300] The gas source 102 and the humidifier 106 can be integrally formed into a single respiratory therapy device 504. In some examples, the gas source 102 and the humidifier 106 can share a single housing 506. The humidification chamber 126 can be removable from the housing 506 for replacement or refilling. In other examples, the housing 506 can be formed of a separate flow generator housing and a humidifier housing that can be attached together to form an integrally formed respiratory therapy device 504.

[0301] The humidifier supply conduit 104 may be or include a conduit within the housing 506 .

[0302] Respiratory therapy device 504 may include a gas inlet 118. Gas inlet 118 may receive ambient air from the environment surrounding respiratory therapy device 504. Gas inlet 118 may include a filter to filter the ambient air.

[0303] The respiratory therapy device 504 can have a supplemental gas inlet (not shown) for receiving supplemental gas (e.g., oxygen) or gas to be supplied to the patient. The respiratory therapy device 504 can have a gas mixer to mix ambient air and supplemental gas together. The controller can be configured to control the concentration of the supplemental gas supplied to the patient, for example using a proportional valve (not shown).

[0304] The gas source 102 and the humidifier 106 may share a single controller (not shown) that controls the operation of any one or more of the chamber heater 128, the heating wire 134, the blower 502, and the proportional valve.

[0305] In some examples, expiratory conduit 114 does not have a heating wire. In other examples, expiratory conduit 114 may have a heating wire. In some examples, expiratory conduit 114 does not have a water trap. In some examples, expiratory conduit 114 does not have either a heating wire or a water trap.

[0306] The technology of the present disclosure is particularly suitable for use in the expiratory conduit 114 of the respiratory assistance system 400.

[0307] One or more of the inspiratory conduit 108 and the expiratory conduit 114 of each of the example respiratory assistance systems 100, 200, 400, 500 (and others) may be sold separately or packaged and sold as part of a breathing circuit kit. The breathing circuit kit may include a combination of any two or more of the following:

[0308] Humidifier supply conduit 104;

[0309] Humidification chamber 126;

[0310] Suction catheter 108;

[0311] Y-shaped member 110;

[0312] Patient interface 112;

[0313] ·Conduit mounting parts;

[0314] · Expiratory duct 114;

[0315] Filters;

[0316] Pressure relief valve 408;

[0317] A pressure regulator 402; and

[0318] Other accessories, such as pressure lines and one or more connector adapters.

[0319] In some examples, the breathing circuit kit may include an inspiratory conduit 108, a Y-piece 110, and an expiratory conduit 114. The breathing circuit kit may optionally include one or more of the other components listed above, such as a humidification chamber 126.

[0320] In some examples, the breathing circuit kit may include a humidifier supply conduit 104, an inspiratory conduit 108, a Y-piece 110, an expiratory conduit 114, and a filter. The breathing circuit kit may also include a humidification chamber 126. The breathing circuit kit may optionally include one or more of the other components listed above.

[0321] In other examples, the breathing circuit kit may include a humidifier supply conduit 104, an inspiratory conduit 108, an expiratory conduit 114, and a pressure regulator 402. The pressure regulator 402 may be a bubbler. The breathing circuit kit may also optionally include one or more of a humidification chamber 126 and a pressure relief valve 408. The breathing circuit kit may optionally include one or more of the other components listed above.

[0322] In some examples, the breathing circuit kit can be partially or fully pre-assembled. Pre-assembly of the breathing circuit can facilitate faster setup of the breathing circuit. Pre-assembly can reduce the risk of incorrect connections, such as misalignment of the inspiratory tube 108 and the expiratory tube 114.

[0323] In some examples, the breathing circuit kits can be packaged together, for example, in a sealed plastic bag. Multiple breathing circuit kits (eg, 10 breathing circuit kits) can be packaged together, for example, in a cardboard box.

[0324] Surgical Insufflation System

[0325] refer to Figure 6 , a surgical insufflation system 600 is shown. The surgical insufflation system 600 can be configured to supply insufflation gas to a body cavity of a patient, for example, to perform laparoscopic surgery.

[0326] In some examples, the insufflation gas may be carbon dioxide. In some examples, a medicament may be added to the insufflation gas.

[0327] The insufflation gas is pressurized to a pressure above atmospheric pressure. The insufflation gas can create a working space within the patient's body (e.g., the abdominal or peritoneal cavity) for the surgeon or surgical team to perform a surgical procedure. The surgical procedure may involve cauterization, thereby generating surgical smoke in the working space.

[0328] The surgical insufflator system 600 may include one or more of a gas source 102, an insufflator supply conduit 602, an insufflator 604, an insufflator gas filter (not shown), a humidifier supply conduit 104, a humidifier 106, a delivery conduit 606, a surgical cannula 608, and a smoke evacuation system 610. In other examples, the surgical insufflator system may include a recirculation system (not shown), for example, in place of the smoke evacuation system 610.

[0329] For example, the gas source 102 may be a wall mounted source 612 or a gas bottle of compressed gas 614. In other examples, the insufflator may be configured to pressurize ambient air.

[0330] One or more insufflation gas filters may be disposed between the insufflator 604 and the surgical cannula 608. An insufflation gas filter may be disposed between the insufflator 604 and the humidifier 106 (e.g., between the outlet of the insufflator 604 and the inlet end of the humidifier supply conduit). Alternatively or additionally, an insufflation gas filter may be disposed between the humidifier 106 and the surgical cannula 608 (e.g., between the outlet of the humidifier 106 and the inlet end of the delivery conduit 606).

[0331] An adapter (not shown) may be provided at the outlet of the insufflator 604 (eg, between the insufflator 604 and the insufflation gas filter or humidifier supply conduit 104).

[0332] In other examples (eg, a surgical insufflator system configured for open surgery), the insufflator gas filter or humidifier supply conduit 104 may be connected directly to the gas outlet port of a CO 2 gas supply station.

[0333] The humidifier 106 may include one or more of a humidification chamber, a chamber heater, a humidifier controller, and a user interface as described above with respect to the example respiratory assistance systems 100, 200, 400, 500. In this example, the humidifier 106 may be the F&P HumiGard 100 also available from Fisher & Paykel Healthcare. TM SH870 Surgical Humidifier. In other example surgical insufflation systems, the humidifier 106 may be omitted, or may be disabled for the entire procedure or a portion of the procedure.

[0334] A funnel may be provided to assist in filling the humidification chamber 126 with a liquid (eg, sterile water) through the inlet or outlet of the humidification chamber 126 .

[0335] The connector at one end of the delivery conduit 606 can be a Luer lock connector. The Luer lock connector can be configured to connect directly to the surgical cannula 608. In other examples (e.g., a surgical insufflation system configured for open surgery), the delivery conduit 606 can instead be configured to connect to a diffuser.

[0336] The delivery conduit 606 can be otherwise similar to the inspiratory conduit 108 of the respiratory assistance system 100, 200, 400, 500. For example, the delivery conduit 606 can have a heater, such as a heating wire 134. In some examples, the delivery conduit 606 can be corrugated. In other examples, the delivery conduit can be spirally wound.

[0337] The smoke exhaust system 610 may include an exhaust duct 616 and an exhaust filter 618 .

[0338] In some examples, the length of the exhaust conduit 616 may be between about 0.8 m and 1.2 m, such as about 1.0 m.

[0339] The smoke exhaust system 610 can be configured to be coupled to a vacuum source 620 (e.g., a wall mounted source). In some examples, the smoke exhaust system 610 can include an additional exhaust conduit 622. The additional exhaust conduit 622 can be configured to be coupled between the exhaust filter 618 and the vacuum source 620. In some examples, the additional exhaust conduit 622 can have substantially the same configuration as the exhaust conduit 616. In some examples, the additional exhaust conduit 622 can have the same length as the exhaust conduit 616. In other examples, the additional exhaust conduit 622 can have a different configuration than the exhaust conduit 616. In some examples, the additional exhaust conduit 622 can differ from the exhaust conduit 616 in one or more of length, diameter, and material.

[0340] The recirculation system (not shown) may include an exhaust conduit 616, an exhaust filter 618, and an additional exhaust conduit coupled to an additional surgical cannula. This may enable the exhausted insufflation gas to be filtered and then recirculated back into the patient's body cavity.

[0341] In the illustrated example, the surgical insufflation system 600, the humidifier supply conduit 104, the humidification chamber 126, the delivery conduit 606, the exhaust conduit 616, the exhaust filter 618, and the additional exhaust conduit 622 form an insufflation circuit. More specifically, this particular configuration forms a dual-branch insufflation circuit 624. It can be said that the humidifier supply conduit 104, the humidification chamber 126, and the delivery conduit 606 form an inlet branch of the dual-branch insufflation circuit 624. It can be said that the smoke evacuation system 610 (e.g., the exhaust conduit 616, the exhaust filter 618, and the additional exhaust conduit 622) form an outlet branch of the dual-branch insufflation circuit 624.

[0342] Figure 6 Also shown are a scope 626 and a laparoscopic monitor 628.

[0343] In use, insufflation gas is supplied from the gas source 102 to the insufflator 604 through the insufflator supply conduit 602. The insufflator 604 can control the pressure of the insufflation gas. The insufflator 604 supplies the insufflation gas to the inlet of the humidifier 106 through the humidifier supply conduit 104. The insufflation gas is heated and humidified by the humidifier 106. The heated and humidified insufflation gas is then supplied to the surgical cannula 608 through the delivery conduit 606 and then enters the patient's body cavity.

[0344] In some examples, the pressure of the insufflator 604 can be set between about 5 mm / Hg and 20 mm / Hg, depending on the patient's size and the desired amount of inflation. The flow rate of the insufflator 604 can be set between about 1 L / min and 12 L / min, depending on the requirements of the specific operation.

[0345] Insufflation gas and surgical smoke (if any) may flow from the patient's body cavity into the surgical cannula 608 and through the exhaust conduit 616 to the exhaust filter 618. In some examples, insufflation gas and surgical smoke (if any) may flow from the patient's body cavity into a dedicated ventilation cannula (not shown) and through the exhaust conduit 616 to the exhaust filter 618. That is, the surgical cannula 608 is not necessarily connected to the exhaust conduit 616.

[0346] The exhaust filter 618 may include a filter medium. The filter medium may capture contaminant materials in the insufflation gas or surgical smoke. The contaminant materials may include one or more of particulate matter, odors, and gaseous hydrocarbons. In some examples, the filtered gas downstream of the exhaust filter 618 may be almost 100% carbon dioxide. In some examples, the exhaust filter removes 99.999% of all particulates, cells, and viruses. In some examples, the exhaust filter may have a retention capacity of up to 0.02 microns. The filtered gas may be exhausted to ambient air. It may be exhausted away from the patient and the surgical team.

[0347] In some examples, the humidifier 106 can be configured to humidify the insufflated gas to saturation or near saturation, i.e., 100% relative humidity. Since the patient's body cavity is already moist and humid, the insufflated gas may not lose much, if any, moisture in the body and may become fully saturated without reaching the saturation point.

[0348] In other examples, the surgical insufflation system may omit the humidifier 106 and may supply relatively dry insufflation gas to the patient, e.g., at a relative humidity of less than about 90%, less than about 80%, or less than about 70%. The relatively dry insufflation gas may be humidified as it passes through the patient's body cavity, absorbing moisture from the relatively warm and humid environment of the body cavity above the internal organs.

[0349] As the insufflation gas exits the patient's body cavity, it passes along the wall of the exhaust conduit 616. The wall, which is exposed to ambient air, may be cooler than the insufflation gas. Water vapor in the insufflation gas may condense from the gas onto the wall of the exhaust conduit 616. Water vapor may also condense on or in one or more other components of the insufflation circuit (e.g., the exhaust filter 618 and the additional exhaust conduit 622).

[0350] One or more of the water vapor condensed in the exhaust filter 618 and the water vapor flowing away from the exhaust conduit 616 may saturate the exhaust filter 618. The exhaust filter 618 may become at least partially blocked. The blockage of the exhaust filter 618 may cause an increase in back pressure. The blockage of the exhaust filter 618 may hinder the dissipation of surgical smoke in the patient's body cavity. The surgical smoke that continues to remain in the patient's body cavity or the exhaust conduit 616 may be harmful to the patient. The surgeon's vision may be blocked or obstructed due to the continued presence of surgical smoke. Obstructed filtration may cause potentially harmful contaminant materials to escape into the operating room.

[0351] The technology of the present disclosure is particularly suitable for use in the smoke evacuation system 610 of the surgical insufflator system 600, for example as one or more of the exhaust conduit 616 and the additional exhaust conduit 622. In some examples, the smoke evacuation system 610 does not have one or more of the heating wire and the water trap. However, in some examples, one or more of the exhaust conduit 616 and the additional exhaust conduit 622 can have a heating wire.

[0352] The smoke evacuation system 610 of the example surgical insufflation system 600 may be sold separately or as part of an insufflation circuit kit. The insufflation circuit kit may include an exhaust conduit 616 and one or more of the following:

[0353] Insufflator supply conduit 602;

[0354] ·adapter;

[0355] Blow into the gas filter;

[0356] Humidifier supply conduit 104;

[0357] Humidification chamber 126;

[0358] ·funnel;

[0359] Delivery catheter 606;

[0360] Surgical cannula 608;

[0361] Diffuser;

[0362] Emission filter 618;

[0363] • Additional discharge conduit 622.

[0364] In one example, the insufflation circuit kit may include a discharge conduit 616 and a discharge filter 618 .

[0365] In another example, the insufflation circuit kit may include an adapter, an insufflation gas filter, a humidifier supply conduit 104 , a humidification chamber 126 , a funnel, a delivery conduit 606 , an exhaust conduit 616 , and an exhaust filter 618 .

[0366] In another example, the insufflation circuit kit may include an insufflation gas filter, a humidifier supply conduit 104 , a humidification chamber 126 , a delivery conduit 606 , and an exhaust conduit 616 and an exhaust filter 618 .

[0367] In some examples, the insufflation circuit kit or one or more components of the kit may be packaged in, for example, a sealed plastic bag. Multiple insufflation circuit kits (eg, 10 insufflation circuit kits) may be packaged together in, for example, a cardboard box.

[0368] In some examples, the insufflation circuit kit may be partially or fully pre-assembled. Pre-assembly may facilitate faster setup of the insufflation circuit. Pre-assembly may reduce the risk of incorrect connection.

[0369] In one example, the insufflation gas filter, the humidifier supply conduit 104, and the humidification chamber 126 can be pre-assembled with each other. In this example, the delivery conduit 606 is not pre-assembled with any other components of the insufflation circuit. The insufflation gas filter, the humidifier supply conduit 104, and the humidification chamber 126 can be non-sterile. The delivery conduit 606 can be sterile. The delivery conduit 606 can be individually packaged, for example, in a sealed plastic bag. The individually packaged delivery conduit 606 can be packaged together with the insufflation gas filter, the humidifier supply conduit 104, and the humidification chamber 126, for example, in another plastic bag.

[0370] Catheter structure

[0371] An example catheter according to the present disclosure will be described below with reference to a catheter 700 suitable for use as an expiratory catheter 114 in an example respiratory assistance system 100, 200, 400, 500. However, in alternative respiratory assistance systems or in other medical systems, the present technology may be suitable for application as any of the other catheters in a respiratory assistance system 100, 200, 400, 500. For example, a catheter according to the present disclosure may be used as an inspiratory catheter 108 configured for use with an anesthesia machine in a breathing circuit, or, for example, as an exhaust catheter 616 in a surgical insufflation system 600.

[0372] The accumulation of condensate in the inspiratory conduit of a respiratory assistance system can be reduced by reducing the level of active humidification, and thereby reducing the relative humidity of the gas delivered to the patient. However, this is not optimal for patient comfort or recovery. It will not necessarily address condensate in the expiratory conduit due to further humidification of the gas in the patient's upper airway during NIV treatment. It will also not necessarily address the drainage of condensate from interstitial patient engagement components (e.g., conduit mountings) into one or more of the inspiratory and expiratory limbs.

[0373] Other options for mitigating condensation in the inspiratory and expiratory tubes include the use of one or more of thermal insulation, water traps, and heaters.

[0374] Insulating the conduit reduces the rate of heat loss of the respiratory gases as they pass along the length of the conduit. For example, the conduit may be provided with an outer jacket of thermally insulating material or air gaps in the conduit wall. However, such insulation may increase one or more of the diameter, weight, and cost of the conduit; compromise the flexibility of the conduit; or be of limited effectiveness. Insulation also does not address condensation that may flow into the conduit from another source (e.g., any one or more of the gas source, filter, Y-piece, conduit mount, and patient interface).

[0375] The water trap is intended to collect accumulated condensate for disposal. The inspiratory and expiratory tubes each typically hang down in a fold between the patient and the ventilator, and condensate may accumulate at the lowest point of the tube. The water trap is usually set at or near the middle of the expiratory limb, so that it is close to the expected lowest point of the expiratory limb in use. But the position of the water trap is fixed and may not necessarily coincide with the lowest point. The medical professional may need to regularly manipulate the catheter by raising its multiple parts so that the accumulated condensate flows toward the water trap and enters it. For example, if it is not done carefully, this may cause some condensate to flow toward the patient or the ventilator at the same time. And, the condensate may be trapped in the corrugation of the catheter. In addition, the additional weight of the water trap and the collected condensate may increase the tube drag. And, the water trap needs to be emptied regularly. This may interrupt the treatment of the patient. Emptying the water trap also brings infection risks. The water trap solves the problem of condensate (once it exists) to some extent. And, it can also solve condensate from other sources to some extent. But it does not address the cause of the problem and has its own drawbacks.

[0376] In some examples, a catheter according to the present disclosure may omit a water trap.

[0377] The heater is intended to maintain or increase the temperature of the respiratory gas above its dew point. This can mitigate the formation of condensation within the catheter. The heater may include a resistive heating wire disposed within the lumen of the catheter or embedded within the wall of the catheter. Potential disadvantages of a heating wire may include one or more of the following:

[0378] An electrical connection needs to be established between the catheter and a power source (e.g., a humidifier for a respiratory assistance system);

[0379] Increased complexity of heating and humidification algorithms;

[0380] The temperature and absolute / relative humidity of the gas received by the ventilator are relatively high;

[0381] · Additional standards specific to heated wire type breathing tubes need to be followed (e.g., International Electrical and Electronic Commission (IEC) 60601-1 (IEC:2005+A1:2012(E)), Section 11.2);

[0382] Shortened shelf life; and

[0383] • Power consumption during use of the heated catheter contributes to the overall carbon footprint, for example approximately 50% of the carbon footprint of the heated catheter over its lifetime.

[0384] An alternative form of heater is a "water jacket" heater whereby heated water (or other liquid) is circulated around the outside of the lumen to heat the flow of breathing gases within the lumen. This has the further disadvantages of increased bulk, weight and cost of the catheter, the additional need to heat and pump water, and the risk of water leaking into the lumen of the catheter.

[0385] In some examples, a catheter according to the present disclosure may omit a heater, such as both a heating wire and a water jacket. In other examples, the catheter may include a heating wire. However, omitting the heating wire may have one or more of the following advantages:

[0386] Simplify manufacturing;

[0387] Reduce manufacturing and material costs;

[0388] Improved usability by avoiding the need to establish an electrical connection between the conduit and a power source (e.g., humidifier 106 or gas source 102);

[0389] Avoid the need for heater control algorithms;

[0390] Improved safety;

[0391] Reduce surface temperature;

[0392] Improve aerodynamic performance;

[0393] Reduced regulatory burden (e.g., International Electrical and Electronics Commission (IEC) 60601-1 (IEC:2005+A1:2012(E)), Section 11.2);

[0394] · reducing the temperature of the gas received at the gas return inlet 140;

[0395] Improved reliability;

[0396] Longer shelf life (e.g. where electrical insulation is the limiting factor);

[0397] Longer duration of use (for example, where electrical insulation is the limiting factor); and

[0398] · Reduce the power consumption and therefore carbon footprint of the conduit.

[0399] Another approach to mitigating condensation within catheters, particularly expiratory catheters, is to form the walls of the catheters from a breathable material (defined in the glossary below). The breathable material is permeable to water molecules, but relatively impermeable to liquid water and respiratory gases. Water molecules within the lumen of such catheters can be absorbed by the breathable material of the wall, diffuse through the breathable material, and desorb into the ambient air according to a gradient moving from the higher humidity side to the lower humidity side. This is known as a dissolution-diffusion mechanism. In contrast, porous membranes (e.g., expanded PTFE (ePTFE) fabrics (e.g., available from WL Gore & Associates) are generally porous membranes that are relatively impermeable to water molecules, but relatively impermeable to liquid water and respiratory gases. The fabric) is permeable to water molecules (and potentially, pathogens) according to a pore flow mechanism, whereby water passes through pores (ie, pores) extending from one side of the membrane to the other.

[0400] Under a scanning electron microscope (SEM) at a magnification of 150x or 2500x, an unfoamed breathable material may not have any channels or pores. A foamed breathable material may have multiple closed-cell voids, but no open channels or pores extending from one major surface to the other. A porous membrane will have open channels or pores extending from one major surface to the other.

[0401] The use of a gas permeable material can reduce the absolute humidity of the breathing gas flow within the lumen as the breathing gases pass along the length of the catheter, and thus reduce the dew point of the breathing gases. An example of such a catheter is the EVAQUA 100 available from Fisher & Paykel Healthcare. TM Expiratory tubes for various breathing circuits using EVAQUA TM Technology RT280 TM and RT340 TM Adult breathing circuits. These expiratory tubes omit the water trap but do include a heated wire. They have been shown to be effective in reducing the formation of condensation within the tube. However, it has been found that, at least under certain conditions, condensation (e.g., from other sources (e.g., tube mounting, patient contribution, nebulizer, etc.)) may still accumulate in the tube during long-term use.

[0402] Details of such gas permeable catheters are disclosed in US Pat. Nos. 6,769,431 and 10,532,177, both assigned to Fisher & Paykel Healthcare Limited.

[0403] It has been found that breathable materials with a relatively high permeability to water molecules may be more effective in mitigating condensation. However, such breathable materials may absorb a relatively large mass of water molecules during use, which has been found to significantly alter the mechanical properties of the catheter.

[0404] This creates challenges in meeting certain standards or other design requirements. Breathing circuit tubing may be required to comply with certain minimum requirements as specified by a formal standard, such as ISO 5367:2014(E) (Anesthetic and respiratory equipment – ​​Breathing sets and connectors). This standard specifies basic requirements such as:

[0405] i. Materials,

[0406] ii. Length,

[0407] iii. Connect,

[0408] iv. Leakage,

[0409] v. Resistance to mobility, and

[0410] vi. Compliance.

[0411] Figure 7 An isometric schematic diagram of an example catheter 700 according to the present disclosure is shown.

[0412] The catheter 700 can be used in a respiratory assistance system, such as Figure 1 , Figure 2 , Figure 4 and Figure 5 In particular, the conduit 700 can be used as the expiratory conduit 114 in the respiratory assistance system 100 and will be described below in this context.

[0413] As shown, the catheter 700 has an elongated tube 702 , a sheath 704 disposed around the elongated tube 702 , and a pair of connectors 706 at respective ends of the elongated tube 702 .

[0414] exist Figures 7 to 16 In each of the foregoing, the construction of the catheter 700 and in particular the construction of the sheath 704 is shown in schematic form for the sake of clarity. Fig.18 and Fig.19 Example configurations of the sheath 704 are described in further detail. Additionally, it will be appreciated that in other examples, the sheath 704 may be omitted.

[0415] In other examples, the conduit can have two (or more) elongated tubes. The two elongated tubes can have different properties. For example, the different properties can include one or more of different materials, corrugations, structures, permeabilities, diameters, insulation, and heating. The two elongated tubes can be arranged end to end. They can be fixed together and fluidically connected by an intermediate connector. For example, the intermediate connector can be arranged at about the midpoint of the conduit or at about one-third of the path along the length of the conduit.

[0416] Both the elongated tube 702 and the sheath 704, and therefore the catheter 700, can be flexible. This can reduce tube drag. As described in further detail below, the flexibility of the elongated tube 702 may vary during use. However, the sheath 704 can mitigate this.

[0417] The conduit 700 can be relatively lightweight. This can reduce tube drag. Omitting the water trap can help make the conduit 700 relatively lightweight. In use, the accumulation of condensate in the water trap may make the conduit relatively heavy. In some examples, in a balanced state, the conduit 700 can have a mass between about 130 gm and 170 gm, between about 140 gm and 160 gm, or between about 145 gm and 155 gm, for example, about 150 grams (gm). In some examples, in a conditional state, the conduit 700 can have a mass between about 260 gm and 300 gm, between about 270 gm and 290 gm, or between about 275 gm and 285 gm, for example, about 280 gm.

[0418] The elongated tube 702 is defined by a tube wall that defines an internal lumen for passing breathing gases from one end of the conduit 700 to the other end. In the illustrated example, the conduit 700 has a single elongated tube 702 and a single lumen, rather than two or more parallel tubes defining two or more parallel lumens. Multiple smaller diameter tubes may be more susceptible to one or more of kinking and clogging, and may be less flexible than an equivalent single tube / lumen.

[0419] The tube wall may have a corrugated profile including a plurality of parallel annular corrugations, as described in further detail below. The corrugations may have one or more of the following advantages: improving flexibility of the elongated tube 702, facilitating controlled deformation, and relieving kinking.

[0420] The corrugations may extend along the length of the elongated tube 702 between the connectors 706. More than 80% or 90% of the length of the elongated tube 702 may be corrugated. The end portions of the elongated tube 702 that are joined by the connectors 706 (described in further detail below) may be non-corrugated. The absence of corrugations in the end portions may improve the seal between the elongated tube 702 and the connector 706. In other examples, the tube wall may have a spiral profile (e.g., a single spiral or a double spiral). In some examples, one or more portions of the elongated tube 702 between the connectors may not have a corrugated / spiral profile.

[0421] The wall of the elongated tube 702 can be formed of a breathable material (described in further detail below) that is permeable to water molecules. The breathable material can be highly permeable to water molecules. The breathable material allows water molecules to pass through the wall to the ambient air. In use, the breathable material of the wall can reduce the absolute humidity of the respiratory gases in the lumen as they pass along the length of the conduit 700. The breathable material of the wall can dissipate condensation or other liquids (e.g., from the patient) that may be present in the lumen. The breathable material can substantially hinder the passage of respiratory gases (e.g., nitrogen, oxygen, carbon dioxide, and helium) through the wall. The breathable material can hinder liquid droplets from passing through the wall. The breathable material can hinder pathogens from passing through the wall.

[0422] In this example, the breathable material forms both the entire length and the perimeter of the elongated tube 702 at least between the connectors 706. In other examples, the breathable material may define only one or more portions having one or more of the length and the perimeter of the elongated tube 702. For example, the breathable material may be co-extruded with another different (e.g., non-breathable) material. The different material may provide structural support to the elongated tube 702.

[0423] Forming the entire elongated tube 702 from a breathable material advantageously provides a relatively large surface area of ​​breathable material, which increases the overall permeability and effectiveness in mitigating condensate of the elongated tube 702. It can also simplify the manufacture of the elongated tube 702. A continuous length of tubing can be extruded and cut to length to form the elongated tube 702, as described in further detail below.

[0424] Other things being equal, the greater the permeability of the breathable material to water molecules, the more effectively the elongated tube 702 may dissipate one or more of water vapor and condensation (if any) from the lumen of the elongated tube 702. However, it has been found that the breathable material absorbs an increasing mass of water molecules relative to the dry mass of the breathable material, for example, absorbing more than about 100% of its own dry mass of water molecules in an immersion test. During use, the mechanical properties of the elongated tube 702 may change significantly. For example, an elongated tube configured to absorb about 100% of its own dry mass of water molecules may be composed of up to 50% water during use and may become significantly more flexible than before use.

[0425] Because the state of the catheter 700 may change during use, throughout the detailed description and claims, the terms "dry," "equilibrium," "conditional," and "saturated" refer to various different states or ranges of states of one or more of the elongated tube 702, sheath 704, and catheter 700. Each of these states is defined in the following glossary.

[0426] In one example, it was found that an elongated tube 702 made of a gas permeable material such that the elongated tube 702 is configured to absorb more than about 120% (e.g., about 133%) of its own mass of water molecules in an immersion test is stiff enough on its own (i.e., without a sheath 704 or other similar structure) to meet the compliance requirements of the standard when in equilibrium or when conditioned, as set forth in the ISO 5367:2014(E) standard. However, when the same elongated tube 702 is used to deliver humidified breathing gases for an extended period of time, it was found that the gas permeable material softens to such an extent that the elongated tube 702 may no longer meet the same compliance requirements when in a conditioned state as defined herein.

[0427] It has also been found that the absorption of such a relatively large mass of water molecules by the elongated tube 702 (e.g., more than 100% of its own dry mass in an immersion test) causes the elongated tube 702 to visibly expand. That is, as the elongated tube 702 absorbs water molecules, there is an increase in the volume of its gas permeable material. In at least some examples, this expansion may be readily apparent to the naked eye during use. In use, the dimensions of one or more of the elongated tube and the sheath may change over time (i.e., as it absorbs and desorbs water molecules over time).

[0428] In some examples, when in a conditional state, one or more of the outer diameter, inner diameter, wall thickness, and corrugation spacing (number of corrugations per unit length) of the elongated tube 702 may vary along the length of the elongated tube 702. While in one or more of a dry state, an equilibrium state, and a saturated state, one or more and possibly all of the outer diameter, inner diameter, wall thickness, and corrugation spacing of the elongated tube 702 may be substantially uniform along at least a central portion of the elongated tube 702. The central portion may exclude end portions of the elongated tube 702. The end portions may be comprised of a corresponding sleeve portion of the elongated tube 702 that tapers toward the connector 706 and a corresponding tapered portion (if any) (see FIG. 2 ). Fig.21 (h) shows the central portion 2102, the end portion 2104, the sleeve portion 1002 and the tapered portion 2106). The expansion of the end portion may be constrained by the corresponding connector 706.

[0429] Although the expansion of the elongated tube 702 may be non-uniform during use (e.g., under conditional conditions), for ease of representation and explanation, Figures 7 to 26 The following description assumes that the dimensional changes of the elongated tube 702 and the sheath 704 occur approximately uniformly. Fig. 27 The uneven absorption and expansion of catheter 700 will be described in further detail.

[0430] Non-contact methods can be used to measure the diameter, length, wall thickness, and other dimensions of the test specimen using computer tomography (CT) scanning or optical measurement systems. In some examples, contact-based measurement methods can be used, such as with a coordinate measuring machine (CMM).

[0431] In an immersion test (described in the glossary below), a sample specimen of the elongated tube 702, separated from the sheath (i.e., without the sheath 704 or other such restraint), can expand from a dry state to a saturated state in one or more of the radial direction (e.g., the maximum outer diameter, the minimum inner diameter, or the average outer or inner diameter for the corrugated elongated tube 702), the longitudinal direction (i.e., the length), and the wall thickness of the tube wall by between about 20% and 70%. In some examples, the sample specimen of the elongated tube 702 can expand between about 20% and 70%, between about 25% and 50%, or between about 30% and 50% in one or more of the radial direction, the longitudinal direction, and the wall thickness. In one example, a sample specimen of the elongated tube 702 of the example catheter 700 was found to expand by about 42% in the radial direction, about 37% in the longitudinal direction, and about 34% in the wall thickness. In another example, a sample specimen of the elongated tube 702 was found to expand by approximately 32% in each of the radial direction, the longitudinal direction, and the wall thickness.

[0432] In some examples, in a dry state, the wall thickness of the elongated tube can be between about 0.5 mm and 0.9 mm, between about 0.6 mm and 0.8 mm, between about 0.65 mm and 0.75 mm, between about 0.68 mm and 0.72 mm, or between about 0.69 mm and 0.71 mm, for example, about 0.70 mm. In a saturated state separated from the sheath, the wall thickness of the same tube wall can be between about 0.7 mm and 1.1 mm, between about 0.8 mm and 1.0 mm, between about 0.85 mm and 0.95 mm, between about 0.90 mm and 0.94 mm, or between about 0.91 mm and 0.93 mm, for example, about 0.92 mm.

[0433] In some examples, in a dry state, the maximum outer diameter of the elongated tube can be between about 20 mm and 26 mm, between about 21 mm and 25 mm, or between about 22 mm and 24 mm, such as about 23 mm. In a saturated state separated from the sheath, the maximum outer diameter of the same elongated tube can be between about 25 mm and 35 mm, between about 28 mm and 32 mm, or between about 29 mm and 31 mm, such as about 30 mm.

[0434] Still reference Figure 7, a sheath 704 is disposed around the elongated tube 702. The sheath 704 is shown in the cutaway view for illustrative purposes, but in this example extends continuously between the connectors 706 at the opposite ends of the conduit 700. The sheath 704 is shown as a generally tubular shape (i.e., circular in cross section), but may not necessarily have a completely circular cross section. In particular, it will be appreciated that the sheath 704 can be formed by cutting to a length from a continuous length of flexible sheath material that can be stored in the form of a roll of flattened sheath. For example, when disposed around the elongated tube 702, the sheath 704 may tend to adopt an elliptical or pointed oval cross section to a greater extent. In addition, the sheath 704 may not necessarily have a uniform shape along its length as shown in the accompanying drawings in cross section.

[0435] In the example shown, the end of the sheath 704 is fixed relative to the end of the elongated tube 702 by a connector 706, as described in further detail below. In this example, the elongated tube 702 and the sheath 704 are not fixed to each other in the middle of the connector 706. In other examples, for example, the elongated tube 702 and the sheath 704 can be further fixed relative to each other at one or more discrete points along the length of the conduit in the middle of the connector 706, such as about the midpoint or about one-third of the path along the length of the elongated tube 702. In other examples, the sheath 704 can only extend to the middle of the length of the elongated tube 702. In one example, the opposite end of the sheath 704 can be fixed to the elongated tube 702 by one of the connector 706 and an additional intermediate connector.

[0436] In yet other examples, the catheter can have two or more sheaths along the length of the catheter. Two or more sheaths can be discrete from each other. Two or more sheaths can have different properties. These different properties can include one or more of different materials, braiding patterns, the number of braided elements, and length / diameter gradients. Two or more sheaths can be arranged end to end with each other. Two or more sheaths can be fixed to the elongated tube 702 by an intermediate connector. The intermediate connector can be arranged at about the midpoint of the catheter or elsewhere (e.g., closer to the patient's end). The intermediate connector can also fix two discretely formed elongated tubes together and connect them fluidically. One or two of the discretely formed elongated tubes can be formed at least in part by a breathable material. The sheath 704 can extend along the entire length of the catheter 700 between the end connectors 706. Alternatively, the sheath 704 can be arranged only around the breathable elongated tube 702.

[0437] The sheath 704 has a plurality of braided elements that are braided into an open mesh tubular configuration defining a plurality of openings, as described below with reference to Fig.18 and Fig.19Detailed description is provided in detail below. The jacket 704 can be highly porous and vapor-permeable, and thus does not inhibit water molecules from passing through the gas-permeable material from the lumen of the elongated tube 702 to the ambient air. That is, water vapor and other gases can freely pass through the jacket 704. The jacket 704 has a negligible or no effect on the temperature and humidity of the ambient gas adjacent to the exterior of the tube wall, so as not to affect the vapor pressure gradient across the tube wall. The open mesh structure of the jacket 704 can also permit visual inspection of the elongated tube 702.

[0438] When the example catheter 700 is in one or more of a dry state and an equilibrium state, the sheath 704 can loosely surround the elongated tube 702. That is, the inner diameter of the sheath 704 can exceed the corresponding outer diameter of the elongated tube 702, such that the sheath 704 is at least partially spaced apart from the elongated tube 702. The elongated tube 702 can be movable relative to the sheath 704 (or vice versa).

[0439] "At least partially spaced apart" is intended to allow some contact between the sheath 704 and the elongated tube 702 around or along one or more of the circumference of the catheter 700 and the length of the catheter 700. That is, the sheath 704 need not (but may) be completely spaced apart from the elongated tube 702. In the case of a corrugated tube, "at least partially spaced apart" refers to spacing from the peaks of the corrugations, not just spacing from the valleys between peaks.

[0440] The sheath 704 may be described or illustrated as being concentric or coaxial with respect to the elongated tube 702, for example, as Fig.15 , but it will be appreciated that in practice, relative movement may occur between the elongated tube 702 and the sheath 704 in one or more of the dry state and the conditioned state. The elongated tube 702 and the sheath 704 will not necessarily share the same center in cross-section. For example, the elongated tube 702 may drape toward the bottom of the sheath 704, or conversely, the sheath 704 may drape toward the top of the elongated tube 702. It will be appreciated that the spacing between the elongated tube 702 and the sheath 704 will therefore not necessarily be uniform in either the circumferential or longitudinal directions of the catheter 700. Furthermore, the sheath 704 may contact the elongated tube 702 in some places and still be considered to be generally partially spaced apart.

[0441] The elongated tube 702 and the sheath 704 are shown as having a relatively uniform diameter along their length. However, in use, and particularly under conditional conditions (as discussed above), the diameter or shape of one or more of the elongated tube 702 and the sheath 704 may vary along their length, as described below with respect to Fig. 27In one example, under conditional conditions, the sheath 704 may engage the entire circumference of the elongated tube 702 in the first portion of the catheter 700, but be spaced apart from the entire or at least a portion of the circumference of the elongated tube 702 at the second portion of the catheter 700. In that example, it can be said that the sheath 704 is at least partially spaced apart from the elongated tube 702 in the second portion. Alternatively, it can be said that the sheath 704 is at least partially spaced apart from the elongated tube 702 as a whole. But particularly in the first portion of the catheter 700, the sheath 704 is not considered to be at least partially spaced apart from the elongated tube 702.

[0442] As the elongated tube 702 absorbs water molecules during use and expands in one or more of the radial direction, the longitudinal direction, and the wall thickness, the sheath 704 can interact with the elongated tube 702, as described in further detail below. In particular, when the catheter 700 is in a constrained conditional state, the sheath 704 can constrain the expansion of at least a portion of the elongated tube 702 in at least one of the longitudinal direction and the radial direction of the catheter 700. That is, the sheath 704 limits the expansion of the elongated tube 702 by applying a reaction force under at least certain conditions.

[0443] The jacket 704 may also provide a degree of physical protection to the elongated tube 702 , such as one or more of strain relief, wear resistance, and distribution of point or localized loads (eg, across a plurality of corrugations of the elongated tube 702 ).

[0444] The connector 706 of the conduit 700 can provide a convenient and reliable pneumatic connection of the elongated tube 702 to other components of the respiratory assistance system to convey respiratory gases between those other components. In particular, in the case where the conduit 700 is intended to be used as an expiratory conduit 114 in the respiratory assistance system 100, the connector 706 is configured to be directly pneumatically connected to the outlet of the Y-piece 110 and the gas return inlet 140 of the gas source 102, respectively. In some examples, a filter can be provided between the conduit 700 and the gas return inlet 140.

[0445] In the example shown, the connector has a standard medical taper to enable interoperability with a wide variety of respiratory assistance systems and their components.

[0446] In some examples, particularly where the catheter has a heated wire, at least one of the connectors may include a receptacle for establishing an electrical connection with the humidifier 106, the gas source 102, or another power source.

[0447] The connectors 706 each define a hole that is fluidly coupled to the lumen of the elongated tube 702 .

[0448] Figure 8A detailed isometric view of one end of a catheter 700 according to the present disclosure is provided, the end including a connector 706, an end portion of a sheath 704, and an end portion of an elongated tube 702 (partially obscured by the sheath 704 and the connector 706). Also shown is a hole 802 of the connector 706 that is fluidly coupled to the lumen of the elongated tube 702.

[0449] Fig. 9 A detailed side view of an end of a catheter 700 according to the present disclosure is provided. Also shown is the so-called longitudinal direction of the catheter 700 (indicated by arrow 902). It will be appreciated that in use, the catheter 700 may not necessarily adopt a strictly linear configuration as shown in the figure, and references to "longitudinal", "axial", etc. will not be construed as limited to such linear configurations.

[0450] The sheath 704 may be a braided tubular sheath, as described below with respect to Fig.18 and Fig.19 described in further detail.

[0451] Fig.10 An exploded detailed view of an end of a catheter 700 according to the present disclosure is provided, the end including one of the connectors 706 and portions of the elongated tube 702 and sheath 704. As shown, the connector 706 has a first connector component 1004 and a second connector component 1006 in this example.

[0452] The first connector component 1004 may have a chamfered edge 1008. The chamfered edge 1008 may aid in inserting the first connector component 1004 into the lumen 1202 of the elongated tube 702.

[0453] The first connector component 1004 can have at least one flange 1010. In some examples, the first connector component 1004 can have three flanges 1010. The flanges 1010 can extend circumferentially around the first connector component 1004. The flanges 1010 can resist inadvertent removal of the first connector component 1004 from one or more of the elongated tube 702, the sheath 704, and the second connector component 1006 (or vice versa). The flanges 1010 can extend radially outward from at least a portion of the first connector component 1004 and can partially define an annular channel 1012. The second connector component 1006 can be partially received within the annular channel 1012. The flanges 1010 can inhibit one or more of the elongated tube 702, the sheath 704, and the second connector component 1006 from sliding off the first connector component in the longitudinal direction.

[0454] The second connector component 1006 may have one or more apertures 1014. The apertures 1014 may be arranged in pairs on opposite sides of the second connector component 1006. The apertures 1014 may be through holes. That is, the apertures may each extend all the way through a cylindrical wall defining a portion of the second connector component 1006.

[0455] The aperture 1014 may illustrate the manufacture of the catheter 700, as described in further detail below. The aperture 1014 may provide an increased grip for a user to connect / disconnect the catheter 700 to / from other components of a breathing assistance system.

[0456] Although the orifice 1014 of the example conduit 700 is arranged as a pair of parallel elongated grooves, there may alternatively be any number of orifices in any suitable shape or arrangement. For example, these orifices may alternatively form a V-shaped pattern or a logo. In some examples, a V-shaped pattern or other markings (such as, text or symbols) may indicate a preferred flow direction or a specific component of a respiratory assistance system (the corresponding connector 706 is intended to be connected to the specific component). This can reduce the risk of misconnection. The example conduit 700 may be symmetrical and may be configured to be connected between a gas source 102 (or filter) and a Y-shaped piece 110 in either direction. In other examples, the conduit may be directional.

[0457] At least one of the first connector component 1004 and the second connector component 1006 may be formed of a polymer material. The polymer material may include any one or more of polycarbonate (PC), polypropylene (PP), and polyethylene (PE). In some examples, the first connector component 1004 and the second connector component 1006 may be formed of the same material. In other examples, the first connector component 1004 and the second connector component 1006 may be formed of different materials.

[0458] The first connector component 1004 may be injection molded. The second connector component 1006 may be overmolded to one or more of the elongated tube 702, the sheath 704, and the first connector component 1004. In some examples, the second connector component 1006 may be overmolded to all three of the elongated tube 702, the sheath 704, and the first connector component 1004.

[0459] In other examples, the sheath 704 may alternatively or additionally be secured to one or more of the connector 706 and the elongated tube 702 by ultrasonic welding, radio frequency (RF) welding, adhesives, hose clamps, clips (eg, circlips or snap clamps), and the like.

[0460] Fig.10702 and the corrugated portion 1016 of the elongated tube 702 are also shown. In this example, the sleeve portion 1002, which is intended to be received between the first connector part 1004 and the second connector part 1006 of the connector 706, is not corrugated. The absence of corrugations in the sleeve portion 1002 may have one or more of the following advantages: assisting in inserting the chamfered edge 1008 into the sleeve portion 1002, promoting a more secure engagement between the elongated tube 702 and the connector 706, and reducing the potential for pneumatic leakage between the elongated tube 702 and the connector 706.

[0461] Fig.11 700 is a cross-sectional view of the end of a catheter 700 according to the present disclosure. For clarity, the sheath 704 is schematically shown. It should be understood that, for example, Fig.21 As shown in (e), the sheath 704 can be tapered to a diameter (eg, inner diameter) equal to that of the connector 706. Due to the nature of the braided tubular mesh sheath, this can be accomplished by extending the length of the portion of the sheath where the smaller diameter is desired.

[0462] The first connector component 1004 defines the aperture 802 of the connector 706. The first connector component 1004 may include a tapered male or female tapered end 1102 configured to connect to other components of the respiratory assistance system (e.g., the gas return inlet 140). The opposite end of the first connector component 1004 may be partially received within the lumen 1202 of the elongated tube 702 (e.g., at the cannula portion 1002). One or more of the elongated tube 702 and the sheath 704 may be exposed (e.g., visible) through the aperture 1014 of the second connector component 1006 of the connector 706.

[0463] As shown, the ends of one or more portions of the elongated tube 702 (e.g., the sleeve portion 1002) and the corresponding ends of the sheath 704 can be fixed relative to each other by one or more of the first connector component 1004 and the second connector component 1006. The ends of the elongated tube 702 and the sheath 704 can coincide within the connector 706. In some examples, one or more of the elongated tube 702 and the sheath 704 can be fixed between (e.g., "sandwiched" by) the first connector component 1004 and the second connector component 1006. In some examples, the sheath 704 can be directly positioned adjacent to the elongated tube 702 within the connector 706. In other examples, as shown, the sheath 704 can be spaced apart from the elongated tube 702 within the connector 706.

[0464] Fig.12An isometric exploded detail view of an end of a catheter 700 according to the present disclosure is provided, the end including an elongated tube 702, a sheath 704, and first and second connector components 1004, 1006 of a connector 706. Also shown are a sleeve portion 1002 and a corrugated portion 1016 of the elongated tube 702, and a portion of a lumen 1202 for passing breathing gases from one end of the catheter 700 to the other end.

[0465] Fig.13 is a detailed partially exploded isometric view of portions of the elongated tube 702 and sheath 704 of the catheter 700 according to the present disclosure. The lumen 1202 defined by the elongated tube 702 is also (partially) shown.

[0466] Fig.14 is a partially exploded side view of portions of an elongated tube 702 and a sheath 704 of a catheter 700 according to the present disclosure.

[0467] For clarity, the sheath 704 is in schematic form. It shows the plurality of clockwise braided elements 904 and counterclockwise braided elements 906 of the sheath 704. The clockwise braided elements 904 and the counterclockwise braided elements 906 can be staggered, as described in further detail below and in Fig.18 and Fig.19 Displayed in.

[0468] Fig.15 A cross section through an elongated tube 702 and a sheath 704 of a catheter 700 is shown in accordance with the present disclosure. For clarity, the connector 706 is omitted.

[0469] It can be observed that, as illustrated, when the example catheter 700 is in an equilibrium state, there may be a spacing 1502 between the outer surface of the elongated tube 702 and the inner surface of the sheath 704. This allows at least a portion of the elongated tube 702 to undergo some expansion in at least one of the radial direction 1504 and the longitudinal direction 902. However, under certain conditions, further expansion of the elongated tube 702 in the radial direction 1504 may become constrained by the sheath 704, as described in further detail below. That is, in this example, the sheath 704 may selectively constrain expansion of the elongated tube 702.

[0470] As explained above, the spacing 1502 need not necessarily be uniform or even continuous around the entire circumference of the catheter 700 or along the length (in the longitudinal direction 902) of the catheter 700. In particular, the sheath 704 need not have a completely circular cross-section or be concentric with the elongated tube 702.

[0471] Fig.15Also shown is a lumen 1202 defined by the tube wall, and an example of a so-called radial direction of the catheter 700 (indicated by arrows 1504).

[0472] Fig.16 is a detailed cross-sectional side view of a portion of a catheter 700 according to the present disclosure. The sheath 704 and the corrugated portion 1016 of the elongated tube 702 are shown. The figure depicts only the upper portion of the catheter 700 in a horizontal orientation for a length with the lumen 1202 towards the lower portion of the figure and ambient air at the upper portion of the figure.

[0473] A space 1502 can be observed between the outer surface of the elongated tube 702 (at the peaks 1602 of the corrugations) and the inner surface of the sheath 704. It can also be observed that, in this example, the valleys 1604 of the corrugated portion 1016 are flattened. That is, the valleys are substantially cylindrical. In contrast, the peaks 1602 can be continuously curved, as shown.

[0474] Breathable material

[0475] The breathable material may be or include a block copolymer, such as a thermoplastic elastomer (TPE) having both a "hard segment" and a "soft segment". In some examples, the hard segment may be a hard, rigid, semi-crystalline polymer that may be hydrophobic (e.g., a polyester such as polybutylene terephthalate (PBT)). In some examples, the soft segment may be a soft, flexible, amorphous, and hydrophilic polymer (e.g., ether macroglycol). The breathable material may combine the hydrophilic properties of the soft segment with the mechanical properties of the hard segment.

[0476] In some examples, the block copolymer may be at least about 90%, at least about 92%, at least about 95%, or at least about 97%, such as about 97% or about 98.5%, of the elongated tube breathable material by one or more of mass, weight, and volume.

[0477] Fig.17 is a graph showing the results of Differential Scanning Calorimetry (DSC) testing (defined in the following glossary) performed on sample specimens of example elongated tubes 702 formed of gas permeable materials in accordance with the present disclosure.

[0478] Fig.17 Line 1702 in shows the differential thermal rate (measured in milliwatts per milligram (mW / mg)) of an example breathable material when heated a second time during a DSC test.

[0479] The peak in line 1702 represents the melting point 1704 of the gas permeable material. As used herein, the term "melting point" refers to the temperature corresponding to a peak in a DSC graph. It will be appreciated that melting may begin before the peak.

[0480] In some examples, the breathable material may have two, three, or more melting points 1704. The temperature at which the lowest melting point 1704 of the breathable material is located may be greater than about 37°C, greater than about 42°C, greater than about 44°C, greater than about 45°C, or greater than about 46°C, such as at a temperature of about 47°C. The temperature at which the lowest melting point 1704 of the breathable material is located may be less than about 108°C, less than about 100°C, less than about 80°C, less than about 60°C, or less than about 50°C. In some examples, the temperature at which the lowest melting point 1704 is located may be between about 37°C and 100°C, between about 40°C and 60°C, or between about 40°C and 50°C.

[0481] In some examples, the breathable material may have a melting point 1704 at a temperature between about 42°C and 52°C, between about 44°C and 50°C, between about 45°C and 49°C, or between about 46°C and 47°C, for example at a temperature of about 47°C.

[0482] In some examples, the breathable material can have a melting point 1704 at a temperature between about 202°C and 212°C, between about 204°C and 210°C, between about 205°C and 209°C, or between about 206°C and 208°C, such as at a temperature of about 207°C.

[0483] In some examples, the breathable material can have a melting point 1704 at a temperature between about 215°C and 225°C, between about 217°C and 223°C, between about 218°C and 222°C, or between about 219°C and 221°C, such as at a temperature of about 220°C.

[0484] In some examples, the breathable material can have two melting points 1704 that are above about 197°C, above about 202°C, above about 204°C, above about 205°C, or above about 206°C, such as at and above about 207°C.

[0485] In some examples, the breathable material can have two melting points 1704, which are located at a temperature between about 202°C and 225°C, between about 204°C and 223°C, between about 205°C and 222°C, or between about 206°C and 221°C, for example, at a temperature of about 207°C to 220°C.

[0486] In some examples, the breathable material can have two melting points 1704 that differ by less than about 23°C, less than about 18°C, less than about 16°C, less than about 15°C, or less than about 14°C, such as about 13°C.

[0487] In some examples, the breathable material may have two melting points 1704 with a temperature difference between about 150°C and 170°C, between about 155°C and 165°C, between about 158°C and 162°C, or between about 159°C and 161°C, for example, with a temperature difference of about 160°C.

[0488] The breathable material may have three melting points 1704. The temperatures at which the three melting points are located may be between about 42°C and 225°C, between about 44°C and 223°C, between about 45°C and 222°C, or between about 46°C and 221°C.

[0489] In one specific example, the temperatures at which the three melting points 1704 are located may be approximately 47° C., 207° C., and 220° C. (all ±5° C., ±3° C., ±2° C., or ±1° C.).

[0490] In some examples, the breathable material may have a minimum melting point that is at a temperature greater than 37° C. (or 42° C., 44° C., 45° C., 46° C.) As described above, 37° C. may correspond to one or more of the temperature of the breathing gas delivered to the patient by the respiratory assistance system and the temperature of the breathing gas exhaled by the patient.

[0491] The lowest melting point of the breathable material may correspond to the melting point of the soft segments of the breathable material. It has been found that selecting a breathable material whose melting points are all above this temperature can mitigate the melting of the soft segments of the breathable material when the catheter is in use to transport heated and humidified breathing gases. At temperatures above the melting point of the soft segments, the soft segments may still be bonded to the hard segments. It is not obvious to the user that there is any "melting" of the elongated tube. However, it has been found that below the lowest melting point, most of the soft segments can remain solid during use and contribute to the structural integrity of the elongated tube. This can enable the use of a higher soft segment to hard segment ratio in the breathable material, which in turn can increase the permeability of the breathable material to water molecules.

[0492] In some examples, the temperature of the breathing gas within the lumen of the inspiratory conduit 108 can be above 37° C. to allow the temperature to drop before the breathing gas is delivered to the patient via the patient interface. In some examples, for example, the temperature of the breathing gas within the lumen of the inspiratory conduit 108 can be as high as 50° C. or 60° C. Therefore, in some examples, the temperature at which the lowest melting point of the breathable material is located can be greater than 50° C., or greater than 60° C.

[0493] It has been found that such breathable materials are particularly suitable for use in catheters in which a heater (e.g., a heating wire) is omitted. The heating wire can be heated to a temperature well above the temperature of the breathing gases within the lumen 1202. It has been found that such heating may cause at least some of the soft segments of the breathable material to melt during use, even if the temperature of the breathing gases does not exceed the lowest melting point. This is particularly true if the heating wire is embedded in or pressed against the wall of the tube. By omitting the heating wire and selecting a breathable material with a melting point above the expected or actual maximum temperature of the breathing gases, at least most of the soft segments will remain solid during use of the catheter and therefore contribute to the mechanical strength of the catheter when in use. In some examples, a sheath may not be required.

[0494] In other examples, the conduit may include a heating wire, and the gas permeable material may be selected to have a minimum melting point higher than the expected or actual maximum temperature of the heating wire during use. In other examples, the conduit may be operated, for example, by controlling the duty cycle of the heating wire so that the temperature of the heating wire does not exceed the minimum melting point of the gas permeable material. In other examples, the elongated tube 702 may be formed of a gas permeable material and an airtight material, and the heating wire may be embedded in or pressed against the airtight material.

[0495] At least a portion of the elongated tube 702 can be configured to absorb more than about 45%, more than about 65%, more than about 75%, more than about 100%, more than about 120%, or more than about 130% (described in the glossary below) of its own mass in water during an immersion test.

[0496] In some examples, a sample of at least a portion of the elongated tube 702 can be configured to absorb between about 45% and 250%, about 65% and 200%, about 75% and 175%, about 100% and 160%, about 110% and 150%, about 120% and 140%, about 130% and 140%, or about 133% and 139%, for example, about 139%, of its own dry mass of water molecules during an immersion test.

[0497] In some examples, a sample of at least a portion of the elongated tube 702 can be configured to absorb between about 40% and 80%, between about 40% and 60%, between about 45% and 55%, or between about 48% and 51%, for example, about 49%, of its own dry mass of water molecules during an immersion test.

[0498] In some examples, a sample of at least a portion of the elongated tube 702 can be configured to absorb between approximately 100% and 250%, between approximately 100% and 180%, between approximately 110% and 150%, between approximately 120% and 140%, between approximately 130% and 145%, or between approximately 135% and 145%, for example, approximately 138% or 139% of its own dry mass of water molecules during an immersion test.

[0499] In some examples, a sample of at least a portion of the elongated tube can be configured to absorb water molecules in excess of about 33%, between about 33% and 200%, between about 100% and 160%, between about 120% and 140%, or between about 130% and 135%, for example, about 133%, of its own mass during an immersion test.

[0500] It has been found that the permeability of the gas permeable materials described herein to water molecules mitigates condensation within the lumen to such an extent that at least one of the heating wire and the water trap can be omitted. In some examples, both the heating wire and the water trap can be omitted.

[0501] In some examples, it has been found that such an elongated tube 702 can be sufficiently permeable to water molecules to passively (i.e., without heating, emptying a water trap, or drain catheter) mitigate condensation within the lumen of the catheter 700 after extended use (e.g., about 24 hours of continuous use). In some examples, there may be no net accumulation of condensate within the lumen after extended use, including condensate from other sources (e.g., catheter mountings). In some examples, catheters according to the present disclosure can be sufficiently breathable that a medical professional is not required to drain condensate from the catheter after extended use (at least when the catheter is used in a conditioned environment (e.g., ambient air in a range of about 20° C. to 24° C. and about 40% to 60% relative humidity)).

[0502] In one example, a conduit having an elongated tube 702 as follows was found to be suitable for use as an expiratory conduit 114 without the need for a heating wire or a water trap under at least some environmental conditions: the elongated tube is configured to absorb between about 45% and 55%, between about 46% and 52%, between about 47% and 51%, or between about 48% and 50%, such as about 49% or about 50% of its own mass of water molecules in an immersion test. It also does not require a sheath 704 or other such measures to compensate for the softening of the elongated tube 702 as it absorbs water molecules in use. That is, in the absence of a sheath 704, under conditional conditions, it was found that the elongated tube alone can meet one or more of the flow resistance and compliance requirements of ISO 5367:2014 (E).

[0503] In another example, a catheter 700 having an elongated tube 702 configured to absorb between about 130% and 140% of its own mass of water molecules in an immersion test, again without a heating wire or water trap, was found suitable for use as an expiratory catheter 114. When compared to the previous example (configured to absorb between about 45% and 55% of water molecules), this example was found to better mitigate condensation across a wider range of environmental conditions. The catheter 700 is provided with a sheath 704. Despite the much greater absorption ratio of water molecules, the catheter 700 was found to meet one or more of the flow resistance and compliance requirements of ISO 5367:2014(E) under conditional conditions.

[0504] In one example, after prolonged use (e.g., about 24 hours), no condensation was found to accumulate at the gas source or within the lumen of the catheter 700 (when the catheter was used as the expiratory catheter 114). After five days of continuous use, condensation was found to accumulate at the gas source at a rate of less than about 1 milliliter per hour (ml / hr) and within the lumen of the catheter 700 at a rate of less than about 2 ml / hr without a heating wire or a water trap. However, in some examples, the catheter may optionally be provided with at least one of a heating wire and a water trap.

[0505] In some examples, the compliance of catheter 700 may depend on the physical interaction between elongated tube 702 and sheath 704. When conditioned over time, the compliance of catheter 700 may vary by 10%, 20%, or even more than 30% (with a sheath vs. without a sheath).

[0506] The breathable material may further include one or more additives. For example, the additives may include one or more of a blowing agent, a colorant, an ultraviolet (UV) stabilizer, a UV absorber, and a processing aid. In some examples, the additive(s) may form up to about 10%, up to about 8%, up to about 5%, or up to about 3%, such as about 3% or 1.5%, of the elongated tube breathable material by one or more of mass, weight, and volume. It will be appreciated that the additives themselves may not necessarily be breathable, but the breathable material as a whole remains breathable with the additives.

[0507] In some examples, the breathable material can be unfoamed. In other examples, the breathable material can be foamed. The breathable material can include a blowing agent additive. The blowing agent can be selected and dosed so that the breathable material is a closed-cell foam. It has been found that voids formed within the foamed breathable material can increase the mass of water that can be absorbed by the breathable material. In one example, when compared to an unfoamed sample of equal dry mass and structure (e.g., a corrugated profile), it was found that a sample of the foamed breathable material absorbed approximately twice the mass of water in an immersion test. The voids can also improve the thermal insulation provided by the tube wall.

[0508] jacket

[0509] Fig.18 A detailed view of a sheath 704 of a catheter 700 according to the present disclosure is provided, wherein the catheter 700 is in an equilibrium state. The sheath 704 is shown to resemble a catheter laid horizontally.

[0510] The sheath 704 may be less elastic than the elongated tube 702 , such that if the elongated tube 702 is squeezed, the recovery of the elongated tube 702 is not constrained by the sheath 704 .

[0511] The sheath 704 can be a mesh. The sheath 704 can have a plurality of braided elements that are interlaced to form a braided tubular mesh.

[0512] In some examples, the sheath may have a biaxial configuration.The braided elements may each be helically arranged around the elongated tube 702 in one of a clockwise or counterclockwise direction.

[0513] Each of the clockwise knit elements 904 may be interlaced with each of the counterclockwise knit elements 906, and vice versa. In some examples, the knit elements may be interlaced in a regular knitting pattern in which a clockwise knit element 904 passes under two counterclockwise knit elements 906 and then passes over two counterclockwise knit elements 906, as shown. In other examples, the knit elements may be interlaced in a diamond knitting pattern in which a clockwise knit element 904 passes under a single counterclockwise knit element 906 and then passes over a single counterclockwise knit element 906.

[0514] The braided elements of the braided tubular mesh sheath 704 can each be oriented at a braiding angle α relative to the longitudinal direction (horizontal direction, as shown) of the catheter 700. In some examples, the braiding angle α can be the same for the clockwise braided element 904 and the counterclockwise braided element 906. In some examples, in a balanced state, the braiding angle α can be between about 35° and 55°, or between about 40° and 50°. In one example, the braiding angle can be about 45°. In some examples, the angle at the intersection between the clockwise braided element 904 and the counterclockwise braided element 906 can be between about 70° and 110°, or between about 80° and 100°. In one example, the angle at the intersection can be about 90°.

[0515] In other examples, braided elements extending in a longitudinal direction parallel to the elongated tube 702 may be advantageous in applications where expansion of the catheter in the longitudinal direction is undesirable. Braided elements extending in a circumferential direction may be advantageous in applications where expansion of the catheter in the radial direction is undesirable.

[0516] In some examples, the sheath may have a triaxial or other configuration.

[0517] In some examples, the respective braid elements 904, 906 are not bonded or otherwise permanently joined to one another where they cross (except where the sheath 704 is fixed relative to the elongated tube 702 (e.g., at the connector 706)). That is, the braid elements 904, 906 can move relative to one another to some extent (subject to frictional forces).

[0518] The sheath 704 may have an open weave. The clockwise knit elements 904 may be spaced apart from one another around the perimeter of the sheath 704. The clockwise knit elements 904 may be substantially equally spaced apart, such as adjacent to the connector 706. The counterclockwise knit elements 906 may be similarly spaced apart from one another.

[0519] The spacing of the braided elements in the braided sheath forms a plurality of openings 908 between the braided elements. The shape of each of these openings can be substantially quadrilateral, for example having a parallelogram shape or a rhombus shape. The geometry of the openings may change during use, thereby undergoing an affine transformation as the size of the sheath 704 changes during use, as described in further detail below.

[0520] In this equilibrium state, the opening 908 may be relatively elongated in the longitudinal direction (horizontal direction, as illustrated) as compared to the tangential direction (vertical direction, as illustrated).

[0521] If the braid elements 904, 906 are not joined or otherwise permanently attached together where they cross, they may undergo some relative movement therebetween as the elongated tube 702 expands and / or contracts in use. It will be appreciated that the spacing between adjacent braid elements may not necessarily be uniform along the length of the catheter. All of the openings 908 will also not necessarily form a perfect parallelogram.

[0522] In some examples, a useful property of the sheath 704 is that the overall length (in the longitudinal direction) and the diameter (in the radial direction) of the sheath 704 can vary in an inverse relationship. That is, as the sheath 704 is stretched in the longitudinal direction, it will tend to contract in the radial direction. Conversely, when the sheath 704 expands in the radial direction, it will tend to contract in the longitudinal direction. It has been found that this property can be exploited in use to at least partially offset changes in the mechanical properties of the elongated tube 702 as the elongated tube expands due to absorption of water molecules, as described in further detail below.

[0523] In practice, the sheath may have limitations in one or more of the minimum diameter and maximum diameter that it can deform to. In some examples, for example, for adult catheters, the sheath 704 can have an inner diameter that can vary between at least about 23 mm and 43 mm (± 2 mm). That is, the sheath 704 can be configured to conform to a rod with an outer diameter ranging between about 23 mm and 43 mm. It will be appreciated that the length of the sheath 704 will also vary across this range. In some examples, the sheath 704 can have an inner diameter that can vary by at least about 20 mm.

[0524] In other examples, for example, for neonatal or pediatric catheters, the sheath can have an inner diameter that can vary between at least about 12 mm and 22 mm (± 2 mm). In some examples, the sheath can have an inner diameter that can vary by at least about 10 mm.

[0525] In some examples, the number of clockwise braided elements 904 can be equal to the number of counterclockwise braided elements 906. In some examples, the sheath 704 can have between about 75 and 125 braided elements, or between about 90 and 100 braided elements. The sheath 704 of the example catheter 700 has a total of about 96 braided elements consisting of 48 clockwise braided elements 904 and 48 counterclockwise braided elements 906. For example, the sheath 704 can be suitable for a catheter 700 intended for use with adult patients.

[0526] In other examples, the sheath may have between about 40 and 60 braid elements, or between about 45 and 55 braid elements, such as about 48 braid elements totaling from 24 clockwise braid elements 904 and 24 counterclockwise braid elements 906. For example, such a sheath may be suitable for catheters used with neonates or pediatric patients.

[0527] In some examples, one or more of the braided elements 904, 906 can have two or more filaments (i.e., the braided element can be multifilament). In other examples, one or more of the braided elements 904, 906 can be a single filament (monofilament). In some examples, each of the braided elements 904, 906 can be multifilament. In the examples shown, each of the braided elements 904, 906 has two adjacent filaments. In another example, such as a sheath suitable for a catheter for use with a neonate or pediatric patient, each of the braided elements can include three adjacent filaments.

[0528] In some examples, such as Fig.18, the filaments 1802 may be interlaced in a regular weave pattern in which a pair of side-by-side filaments 1802 passes under two pairs of side-by-side filaments 1802 and then passes over two pairs of side-by-side filaments 1802. In other examples, the filaments 1802 may be interlaced in a regular weave pattern in which a single filament 1802 passes under two single filaments 1802 and then passes over two single filaments 1802. In other examples, the filaments 1802 may be interlaced in a diamond weave pattern in which a pair of side-by-side filaments 1802 passes under a pair of side-by-side filaments 1802 and then passes over a pair of side-by-side filaments 1802. In other examples, the filaments 1802 may be interlaced in a diamond-shaped weave pattern in which single filaments 1802 pass under single filaments 1802 and then pass over single filaments 1802 .

[0529] In some examples, the filaments of each braid element are untwisted. In other examples, the filaments of each braid element can be twisted or braided with each other.

[0530] In the illustrated example, the cross-section of the filament 1802 can be substantially circular. In other examples, the filament can have a polygonal cross-section, such as a triangle, square, pentagon, hexagon, octagon, etc. In other examples, the filament can have a circular cross-section, such as an oval, ellipse, rounded polygon, etc.

[0531] The filaments 1802 of the example sheath 704 can be formed of polyethylene terephthalate (PET). In other examples, the filaments 1802 can be formed of any one or more of metals, polymers, ceramics, and fiber materials.

[0532] Filament 1802 and one or more of knit elements 904 , 906 , either individually or collectively, may be substantially inextensible under loads to which they will be subjected in normal use.

[0533] In some examples, the number of filaments in the clockwise braid element 904 can be equal to the number of filaments in the counterclockwise braid element 906. In some examples, the sheath can have between about 150 and 250 filaments, or between about 180 and 200 filaments. The sheath 704 of the example catheter 700 can have a total of about 192 filaments.

[0534] In other examples, such as a sheath suitable for a catheter used with neonatal or pediatric patients, the sheath may have between about 120 and 180 filaments, or between about 135 and 165 filaments, such as about 144 filaments total.

[0535] In some examples, the filaments may all have the same diameter. In other examples, the filaments may have two or more different diameters.

[0536] In some examples, the filaments may have a diameter between about 0.1 mm and 0.4 mm, or between about 0.2 mm and 0.3 mm. The sheath 704 of the example catheter 700 may have filaments having a diameter of about 0.25 mm.

[0537] Fig.19 The sheath 704 is shown in a conditional state.

[0538] As the sheath 704 expands and contracts in the longitudinal and radial directions, the opening 908 may undergo an affine transformation. That is, the shape of the opening 908 changes. The pitch of the braid elements 904, 906 (that is, the angle of the braid elements and therefore the number of helical windings per unit length around the elongated tube 702) may vary.

[0539] In this equilibrium state, the opening 908 may be relatively elongated in the tangential direction as compared to the longitudinal direction.

[0540] When with Fig.18 When compared to the equilibrium state shown in Fig.19 The openings 908 in the longitudinal direction are relatively short. Also, they are relatively long in the tangential direction.

[0541] The length and diameter of the sheath 704 may be inversely related. Tubular meshes of different braids may be characterized by a gradient in their length to diameter (L / D) relationship.

[0542] Fig. 20 A graph showing the length and diameter gradients of several example tubular meshes of different weaves.

[0543] The characterization process is implemented by cutting a sample coupon of the braided tubular mesh sheath into a predetermined length (e.g., 2000 mm) when flattened (as typically stored), and then measuring the length of the sample coupon as it is mounted on and conforms to a plurality of steel rods of suitable known diameter (e.g., between about 22 mm and 32 mm, or between about 23 mm and 32 mm for adult catheters). In some examples, the length to diameter gradient can be substantially linear within this range. Different initial lengths and diameters can produce similar characteristic responses depending on the configuration of the braided element. The length to diameter gradient can be determined by plotting these measurements and the associated linear trend line on a graph. Fig. 20 Sheaths with length to diameter gradients of about -23, -34, -37, -43, and -79 are shown.

[0544] A braided tubular mesh with a relatively large absolute value of the length to diameter gradient will result in a relatively large decrease in the length of the elongated tube as the diameter increases (and vice versa). A smaller absolute value of the length to diameter gradient results in a smaller change in axial length for the same increase in diameter.

[0545] In some examples, such as for adult catheters, the length to diameter gradient of the sheath 704 of the catheter 700 can be between about -100 and -20, between about -50 and -20, or between about -40 and -35. In one example, the length to diameter gradient can be about -37.

[0546] In other examples, such as for neonatal or pediatric catheters, the sheath length to diameter gradient can be between about -75 and -25, between about -60 and -40, or between about -55 and -45. In one example, the length to diameter gradient can be about -52.

[0547] The gap 1502 between the elongated tube 702 and the sheath 704 can be created by cutting the braided tubular mesh selected for the sheath 704 to a length that is a predetermined distance greater than the length of the elongated tube 702 when the sheath 704 conforms to the outside of the elongated tube 702 (i.e., the maximum outer diameter of the elongated tube 702 is at the peak of the corrugation). The predetermined distance can be selected so that the final length of the catheter in a conditioned state is similar to the length of the tube in an equilibrium state, as described above. The sheath 704 is axially compressed before being fixed to the elongated tube 702 so that the respective ends of the elongated tube 702 and the sheath 704 coincide, thereby increasing the average diameter of the sheath 704 to create the gap 1502. A relatively small characteristic length to diameter gradient can provide one or more of the following advantages: minimizing the gap 1502, which can improve aesthetics; and minimizing the flat length of the braided tubular mesh, which can reduce manufacturing costs.

[0548] In some examples, the sheath 704 may also mitigate vibration or oscillation of the conduit during use. The permeable material used for the elongated tube 702 has specific properties that cause dimensional and mechanical changes as water molecules are absorbed into the permeable material and diffuse through the permeable material at a rate that depends on the temperature and humidity boundary conditions on either side of the permeable material. Specifically, the permeable material softens and enlarges as it ingests water molecules. When the permeable material is formed into an elongated tube that carries humid gases (whose humidity level is greater than the humidity level outside the tube wall), as the respiratory gases entering the elongated tube pass through the elongated tube to the outlet due to natural diffusion through the permeable material and the resulting temperature drop, the humidity of these respiratory gases can be reduced axially, which is due to both the heat transfer rate depending on the boundary conditions across the permeable material and the diffusion of water molecules into the permeable material while the vapor pressure gradient remains positive across the tube wall. This may cause axial changes in the conduit size and mechanical properties. Therefore, as water molecules are absorbed into the permeable material and diffuse through it, the permeable material has the properties of a functionally gradient material (FGM). The diameter and length of the sheath can be selected so that radial expansion and longitudinal expansion can be selectively controlled. At the entrance of the catheter (where high humidity breathing gas can enter), the uptake of water molecules may be the largest compared to the axial position far from the entrance. In some examples, the sheath parameters can be selected to alleviate or minimize the expansion of the elongated tube in the longitudinal direction (relative to the equilibrium state), thereby facilitating the radial expansion of the hydraulic diameter of the elongated tube. The uptake of water molecules combined with the corrugated profile and the resulting longitudinal contraction of the elongated tube by the sheath may have the result of producing a thicker wall section relative to the equilibrium state. Therefore, the wall thickness of the tube wall can vary axially, and when the sheath is engaged, once sufficient dimensional changes occur, this change may be more obvious. Although the breathable material can soften due to the uptake of water molecules, the axial growth restriction caused by the sheath may reduce the separation distance between the corrugation peaks. This reduced separation distance can have a dual effect: increased wall thickness and the presence of increased hoop strength. The hardness of the tube can depend on the wall thickness, inner surface finish, hydraulic diameter and material properties. Bending modes of the tube are excited when the gas velocity exceeds a certain critical value (critical velocity), which depends on the hydraulic diameter and the inner surface roughness relative to the length. By controlling the longitudinal and radial expansion of the elongated tube, the sheath can therefore indirectly affect the critical velocity relative to a tube with uniform hydraulic diameter and uniform wall thickness. Specifically, the critical velocity of the respiratory gases may be increased, potentially up to several times relative to an equivalent tube with uniform wall thickness and hydraulic diameter. Thus, for the operating length of the elongated tube, the sheath can reduce the likelihood of vibration modes occurring along the elongated tube when delivering humidified respiratory gases at typical maximum velocities suitable for treatment.

[0549] Expansion of long tubes during use

[0550] The following will refer to Figure 21 to Figure 26 The use and behavior of the example catheter 700 are described by way of example. It will be appreciated that this description relates only to a specific example, and that the structure and arrangement of the catheters in other examples may be selected to behave in a different manner. In other examples, the catheter may be configured and arranged to expand alternately primarily in the longitudinal direction, or by selecting a sheath with appropriate properties (e.g., braid pattern, length to diameter gradient, etc.), the expansion may be limited to only one of the longitudinal or radial directions.

[0551] Will understand, Fig.21 The diagrams are not shown to scale, and the size and scale changes between the different states may be exaggerated for illustrative purposes. In addition to the taper toward the connector 706, Fig.21 Also shown is a substantially uniform expansion of the elongated tube 702. As described elsewhere, in use, the expansion may not necessarily be uniform.

[0552] Fig.21 (a) to (d) (in Fig.21 ) schematically shows an elongated tube 702 without a sheath 704 and a pair of connectors 706 (referred to as a sheathless catheter 2108) in various different states.

[0553] Fig.21 (e) to (h) (in Fig.21 ) schematically illustrates the previously described example catheter 700 in various different states, the catheter including the sheath 704.

[0554] Fig.21 (a) and (e) show the unsheathed catheter 2108 and catheter 700, respectively, in an equilibrium state (unpressurized).

[0555] Fig.21 (b) and (f) show the unsheathed catheter 2108 and catheter 700, respectively, in a partially conditioned state (not pressurized). It can be observed that both the unsheathed catheter 2108 and catheter 700 expand in both the radial and longitudinal directions. However, the expansion of catheter 700 is less than that of the unsheathed catheter 2108.

[0556] Fig.21 (c) and (g) show the unsheathed catheter 2108 and catheter 700 in a conditioned state (unpressurized) after long-term use, respectively. It can be observed that the unsheathed catheter 2108 is further expanded in both the radial direction and the longitudinal direction. While the catheter 700 is further expanded in the radial direction, but contracted in the longitudinal direction. The catheter 700 can be restored to or close to its original length.

[0557] Fig.21 (d) and (h) show the unsheathed catheter 2108 and catheter 700, respectively, in the same conditioned state (but this time pressurized) after prolonged use. It can be observed that the unsheathed catheter 2108 has expanded further in both the radial and longitudinal directions. However, the catheter 700 remains unchanged.

[0558] refer to Fig.21 (a) and (e), when respiratory therapy for the patient is about to begin, a new breathing circuit 142 can be set up with the gas source 102. The catheter 700 can be removed from the package, wherein the gas in the lumen 1202 has approximately the same temperature and humidity as the gas outside the wall of the elongated tube 702 in the package. That is, there is no vapor pressure difference to drive the transport of water molecules through the wall of the elongated tube 702. The gas in the package can have a temperature and relative humidity similar to that of the ambient air, and thus the catheter 700 may be in a state of equilibrium or near equilibrium when removed from the package. In some cases, the catheter 700 can be retained for a period of time after being removed from the package and before use (e.g., stored in preparation for use), wherein the ambient air fills the lumen of the elongated tube 702. If the humidity of the ambient air is different from the humidity in the package, the elongated tube 702 can absorb or desorb water molecules when it reaches equilibrium with the ambient air. Fig.21 (a) and Fig.21 (e) shows the unsheathed catheter 2108 and the catheter 700 in this equilibrium state, respectively. In this state, there is a gap 1502 between the elongated tube 702 and the sheath 704 of the catheter 700, as described above.

[0559] The sheath 704 can be configured to be at least partially spaced apart from the elongated tube 702 in this equilibrium state. Such spacing can mitigate further stiffening of the catheter 700 in the equilibrium state. An overly stiff catheter 700 can be problematic for usability. For example, it can increase tube drag on the Y-piece 110 or the patient interface 112. In some examples, in this equilibrium state, the sheath 704 may have no contribution or a negligible contribution to the stiffness of the catheter 700.

[0560] like Fig.21 As shown in (e), in at least the equilibrium state, the sheath 704 can taper towards the corresponding connector 706 at its respective end.

[0561] It has been found that the gas permeable material of the elongated tube 702 may be sufficiently stiff so that the catheter 700 meets one or more of the compliance and flow resistance requirements of the ISO 5367:2014 (E) standard when in an equilibrium state or when conditional as stated in the standard. However, in a conditional state as defined herein, the catheter 700 may not necessarily meet one or more of these requirements.

[0562] Once the catheter 700 is connected to the respiratory assistance system and treatment is initiated, the lumen of the elongated tube 702 is exposed to a flow of breathing gas at the patient end, which can be above 90% and often about 100% relative humidity. The relative humidity of the ambient air can be between about 10% and 90%, and is often in the range of about 40% to 60% or 45% to 55%, which ranges are recommended for daily health and comfort. There is a partial pressure difference of water vapor between the breathing gas in the lumen 1202 and the ambient air outside the elongated tube 702. The solution-diffusion mechanism causes the breathable material of the elongated tube 702 to continuously absorb water molecules from the breathing gas and condensate (if any) or other liquids (if any) in the lumen, and desorb the water molecules to the ambient air outside the elongated tube 702 according to the driving gradient.

[0563] As referenced below Fig. 27 As described in further detail, expansion of the elongated tube 702 under conditional conditions in use may not necessarily be uniform along the length of the elongated tube 702. However, for purposes of explanation, the following description assumes that dimensional changes of the elongated tube 702 and sheath 704 occur substantially uniformly.

[0564] The initial absorption of water molecules from within the lumen causes the unsheathed catheter 2108 and the elongated tube 702 of the catheter 700 to tend to expand in both the longitudinal direction 902 and the radial direction 1504 (as well as in wall thickness).

[0565] In the case of an unsheathed catheter 2108, this expansion is unrestrained, e.g. Fig.21 As shown in (b).

[0566] In the case of catheter 700, the spacing 1502 between the elongated tube 702 and the sheath 704 means that the elongated tube 702 can expand slightly in both the longitudinal direction and the radial direction. The expansion of the elongated tube 702 in the longitudinal direction will cause a corresponding elongation of the sheath 704. The elongation of the elongated tube 702 and the sheath 704 may in turn cause the sheath 704 to contract in the radial direction.

[0567] like Fig.21As shown in (c) and (g), long-term use of the catheter 700 and exposure to humidity differences (i.e., further absorption of water molecules) may cause the elongated tube 702 to engage the inner surface of the sheath 704. The spacing 1502 between the elongated tube 702 and the sheath 704 may be eliminated along at least a portion of the length of the elongated tube 702. Further expansion of the elongated tube 702 in at least one of the radial direction and the longitudinal direction may be constrained by the sheath 704. That is, each of the braided elements of the sheath 704 is in tension, and the sheath 704 has hoop stress due to the expansion of the elongated tube 702 and engagement with the elongated tube.

[0568] As the elongated tube 702 continues to absorb water molecules from the lumen, some further radial expansion of the elongated tube 702 may occur. This may cause the sheath 704 to shrink in the longitudinal direction. The catheter 700 may return to or approach (e.g., between about 90% and 110%) its original length (at equilibrium).

[0569] like Fig.21 As shown in (d), pressurization of the unsheathed catheter 2108 may cause further expansion in both the radial and longitudinal directions. This may be due in part to softening of the gas permeable material due to absorption of relatively large mass water molecules. However, the sheath 704 constrains further expansion of the catheter 700, as shown in FIG. Fig.21 As shown in (h).

[0570] As described above, as the length of the elongated tube 702 changes during use, the corrugation pitch (i.e., the distance between adjacent peaks of the corrugations in the elongated tube 702) may also change. However, in the catheter 700, for example, such variation is constrained by the sheath 704, such as from Fig.21 (b) (without sheath) and Fig.21 Where the interaction between the elongated tube 702 and the sheath 704 causes the elongated tube 702 to initially expand in the longitudinal direction and then contract to return to or approach its original length, it will be appreciated that the corrugation pitch of the elongated tube 702 will similarly increase and then decrease to return to or approach the original corrugation pitch.

[0571] As described elsewhere, the elongated tube 702 may not necessarily absorb water molecules uniformly along the length of the corrugated portion 1016. In particular, it will be appreciated that as the respiratory gases in the lumen pass along the length of the elongated tube 702 toward the gas return inlet 140, they may have a higher absolute humidity at the patient end of the catheter due to the dehumidification effect of the breathable material on the respiratory gases. In addition, gravity will cause any condensation that does form within the lumen to be drained toward the lowest portion of one or more of the annular corrugations 2202 and the elongated tube 702 (as a whole) and accumulate there. This may cause the breathable material of the elongated tube 702 to absorb a higher concentration of water molecules in a first region of the elongated tube 702 (when compared to a second region of the elongated tube 702). This in turn may cause the breathable material in the first region to locally expand in one or more of the radial direction and the longitudinal direction. Furthermore, the pitch of the corrugations 2202 (the number of corrugations per unit length) may vary along the length of the elongated tube 702.

[0572] The sheath 704 can permit the elongated tube 702 to expand in the first region to a greater extent than if the absorption and expansion were uniform along the length of the elongated tube 702. The diameter of the elongated tube 702 in the first region can exceed the average diameter of the elongated tube 702 as a whole. The expansion of the elongated tube 702 in the first region can take up slack in the sheath 704 due to the spaces 1502 in the second region of the elongated tube 702. This localized expansion can increase the surface area and permeability of the breathable material in the first region of the elongated tube 702, relative to the second region, where the increased permeability is most desirable (i.e., in the region with the highest concentration of water molecules within the lumen, where condensation is present or most likely to form).

[0573] It will be appreciated that the behavior of the catheter according to the present disclosure can be modified or adjusted by changing a number of factors to meet specific design requirements. It has been found that a number of factors can affect the behavior of the catheter according to the present disclosure, including at least the following:

[0574] i. Length / diameter (L / D) characteristics of the sheath,

[0575] ii. the profile and spacing of the corrugations of the elongated tube, and

[0576] iii. The spacing between the elongated tube and the sheath.

[0577] Fig. 22 An example profile of the corrugations 2202 of the elongated tube 702 in equilibrium is shown in cross section. The sheath 704 is omitted from this figure. The figure depicts only the upper portion of a length of the elongated tube 702 in a horizontal orientation, with the lumen 1202 towards the lower portion of the figure and ambient air at the upper portion of the figure.

[0578] Each of the corrugations 2202 has sidewalls 2204 that converge toward the peak 1602 of the corrugation 2202 (ie, defining the maximum outer diameter of the corrugation 2202 and the elongated tube 702) when the elongated tube 702 is balanced.

[0579] The peaks 1602 may be substantially circular. The valleys 1604 of each of the corrugations 2202 may be substantially flattened. That is, each valley region may be substantially cylindrical (at least when the elongated tubes 702 are arranged in a linear configuration).

[0580] Fig.23 The cross section shows when the elongated tube 702 is in a conditional state and more particularly in a conditional state where the expansion of the elongated tube 702 is constrained by the sheath 704. Fig. 22 The outline of the corrugation 2202.

[0581] As the material of the elongated tube 702 expands due to the absorption of water molecules, the sheath 704 constrains the expansion of the elongated tube 702 in the longitudinal direction, as described above. The expansion of the elongated tube 702 against the constraint of the sheath 704 may cause the corrugations 2202 to be compressed more tightly together in the longitudinal direction. This in turn may cause the profile of the corrugations 2202 to change from Fig. 22 The cross section shown in becomes Fig.23 That is, as the elongated tube 702 expands against the constraints of the sheath 704, the sidewalls can be reoriented toward the radial direction (i.e., the vertical direction, as shown) and potentially beyond the radial direction. The sidewalls can be reoriented from an acute angle with the longitudinal direction toward the radial direction (90° relative to the longitudinal direction), and potentially even beyond the radial direction to form an obtuse angle with the longitudinal direction.

[0582] exist Fig.23 In the particular conditional state shown in , each of the side walls 2204 has a substantially radial orientation (extending vertically in the cross-sectional view at 90° relative to the longitudinal direction) whereby the side walls 2204 are substantially planar and adjacent side walls 2204 are substantially parallel to each other (at least when the elongated tubes 702 are arranged in a linear configuration).

[0583] When with Fig. 22 The peaks 1602 where the corrugations 2202 join the adjacent sidewalls 2204 may also become relatively flattened when compared to the initial profile of the corrugations 2202. That is, the peaks of the corrugations 2202 may become substantially cylindrical, such as Fig.23 In the equilibrium state, the peak can bend continuously in the middle of the side wall 2204, as shown in FIG. Fig. 22 as shown in .

[0584] Fig.23The radial orientation of the sidewall 2204 in FIG. 2 means that the force vector 2206 (in this example, equivalent to the radial force component F R ) against any radially inward compressive forces. For example, compressive forces may be caused by the weight of the patient's arm pressing against the catheter. On the other hand, the sheathless catheter 2108 may tend to maintain the same Fig. 22 The corrugation profile is roughly similar to the corrugation profile. Fig. 22 The force vector 2206 in the radial direction includes a radial force component F R and the axial force component F in the longitudinal direction A Both. Radial force component F R Can be relatively smaller than Fig.23 The radial force component in .

[0585] The corrugations may tend to compress more tightly together as the material expands due to the axial constraint of the sheath 704 on the elongated tube 702. This axial "spring compression force" may follow Hooke's law, which stiffens the elongated tube 702 and acts against the atmospheric pressure that axially compresses the elongated tube 702 as the internal pressure decreases.

[0586] The longitudinal constraint imposed by the jacket 704 may cause corrugation growth (due to absorption of water molecules) to occur into the gaps between the corrugations 2202 (i.e., thicker corrugations). The radial constraint may cause the corrugations to grow radially inward (toward the center of the elongated tube 702). In some examples, the gaps between the corrugations 2202 may be partially or completely closed, potentially creating an effectively single thick-walled section without any pivot point or moment effects from the corrugation radius.

[0587] One or more of these effects arising from the interaction between the elongated tube 702 and the sheath 704 as the elongated tube 702 expands due to the absorption of water molecules can mitigate the softening of the breathable material. This can enable the catheter 700 to comply with one or more of the relevant standards and other self-imposed design requirements throughout a range of different operating conditions. For example, in tests under conditional conditions, it has been found that a particular example unsheathed catheter 2108 has a compliance of more than 4 milliliters per centimeter of water (ml / cmH2O) or 5 ml / cmH2O (defined in the following glossary). In some examples, under conditional conditions as defined herein, when tested separately according to the ISO 5367:2014 (E) standard, the catheter 700 with a sheath 704 of the present disclosure can have a compliance of less than about 4 ml / cmH2O, less than about 2.5 ml / cmH2O, or less than about 1.2 ml / cmH2O.

[0588] In other examples, by selecting a breathable material or otherwise configuring the elongated tube to absorb a relatively low proportion of water molecules (e.g., between approximately 40% and 60% of its dry mass), compliance criteria can be met across a range or sub-range of expected operating conditions (conditional states).

[0589] Fig.23 Also shown is an alternative sheath 704 in which each braid element has three filaments 1802 arranged side by side.

[0590] Fig.24 A cross section of a portion of the elongated tube 702 of the catheter 700 is shown when in an equilibrium state where the elongated tube 702 is not constrained by a sheath 704 (not shown in this figure).

[0591] The sidewalls 2204 of each corrugation 2202 generally converge toward the peak 1602 of the corrugation 2202. In some examples, the sidewalls 2204 can be configured to extend from adjacent valleys at an angle θ between about 65° and 85°, or between about 70° and 80°, relative to the longitudinal direction (horizontal direction, as illustrated in the figure) in this equilibrium state. Fig.24 In the example elongated tube 702 depicted in FIG. 2 , the sidewall 2204 may extend at an angle θ of approximately 75° in an equilibrium state.

[0592] exist Fig.24 2204, the valleys can be relatively flattened. In a cross section where the elongated tube 702 is arranged substantially linearly between adjacent side walls 2204, as shown, the outer surface of the valleys can be substantially linear. The outer surface of the elongated tube 702 can be substantially cylindrical at the valleys. In contrast, the peaks 1602 can be substantially continuously curved between adjacent side walls 2204.

[0593] Fig.25 is a cross-section of the elongated tube 702 in a conditional state in the absence of the sheath 704 that constrains the expansion of the elongated tube 702. Fig.25 So with Fig.24 Depicted in approximately the same proportions.

[0594] It can be observed that there are fewer ripples 2202 (compared to the length of the elongated tube 702) for a given length of the elongated tube 702 due to the unconstrained expansion of the elongated tube 702 in the longitudinal direction (horizontal direction, as shown in the figure) when absorbing water molecules. Fig.24 Compared with about 4 ripples in 2202, Fig.25 The sidewall 2204 of each corrugation 2202 is generally similar to Fig.24 In the equilibrium state, the peaks of the corrugations converge at about the same angle θ. That is, in the absence of a sheath, it is found that Fig.25The sidewall 2204 of the example elongated tube 702 extends at an angle θ of approximately 75° in a conditional state.

[0595] It can also be observed that, due to the unrestrained expansion of the elongated tube 702, the depth 2402 of the corrugation (measured from the peak 1602 of the corrugation 2202 to the adjacent valley 1604 at the outer surface of the elongated tube 702) is Fig.25 The conditional state depicted is about 33% larger.

[0596] Fig.26 is a cross-section of the elongated tube 702 in a conditioned state, this time constrained by a sheath 704 (not shown). Fig.26 So with Fig.24 and Fig.25 Depicted in approximately the same proportions.

[0597] It can be observed that the ripple spacing is Fig.24 The corrugation spacing in the equilibrium state is approximately the same. That is, in the displayed length of the elongated tube 702, the elongated tube 702 has approximately four corrugations 2202.

[0598] In this constrained conditional state, the sidewalls 2204 of the corrugations 2202 do not converge continuously from the valleys to the peaks of the corrugations 2202. In some examples, the sidewalls 2204 may form an angle θ greater than 85°, about 90°, or greater than 90° (an obtuse angle). That is, from the adjacent valleys 1604 toward the intermediate peaks 1602, the sidewalls 2204 of the corrugations first diverge, and then converge toward the peaks 1602.

[0599] The sidewall 2204 may be reoriented from an initial angle (75° in this example) toward a radial direction (90°), and in some cases beyond the radial direction (forming an obtuse angle θ, as shown in FIG. Fig.26 ).

[0600] exist Fig.26 In the example elongated tube 702 depicted in FIG, the sidewalls 2204 are found to extend at an angle θ of approximately 95°. There may be inflection points within each of the sidewalls 2204 and at the peaks and valleys of each corrugation 2202.

[0601] Fig.26 The profile of each of the corrugations 2202 in is substantially omega (Ω) shaped, while Fig.21 and Fig. 22 In FIG. 2 , the cross-section of the corrugation 2202 is generally more sinusoidal (although with flattened valleys in this example). Fig.26 In the case of Fig.21 and 22This can form an inner narrowed waist region 2602 and an outer narrowed waist region 2604 between the facing side walls 2204 of adjacent corrugations 2202, in the middle of the corresponding peaks and valleys.

[0602] Uneven expansion

[0603] Fig. 27 The catheter 700 according to the present disclosure is shown after long-term use as the expiratory catheter 114 of the exemplary respiratory assistance system 2700. The figure is not necessarily drawn to scale. In particular, the expansion of the elongated tube 702 or the sheath 704 may be exaggerated for illustrative purposes. Also, the inspiratory catheter 108 and the expiratory catheter 114 are not shown to scale.

[0604] Breathing assistance system 2700 may be similar to breathing assistance system 100 , except as apparent from the figures and the following description.

[0605] Fig. 27 A filter 2702 is shown at the gas return inlet 140 of the gas source 102. The filter 2702 may be connected directly between the expiratory conduit 114 and the gas return inlet of the gas source 102.

[0606] In this example, the humidifier 106 may be a F&P 820 also available from Fisher & Paykel Healthcare Limited. TM Heated humidifier.

[0607] In this example, the breathing assistance system 2700 is shown in use after delivering humidified breathing gases to a patient (not shown) for an extended period of time. It will be appreciated that this represents only one of a number of different possible conditional states that will depend on a number of variables including, but not limited to, for example, time of use, temperature of the breathing gases, humidity of the breathing gases, temperature of the ambient air, humidity of the ambient air, routing of the conduit, type and model of gas source, patient condition and humidity contribution, aerosolized material, and any breeze on the conduit.

[0608] In this example, expiratory limb 146 , and in particular expiratory conduit 114 , omits both a heating wire and a water trap.

[0609] As shown, the expiratory conduit 114, or more particularly the elongated tube 702 and the sheath 704, is flexible in at least this conditional state. The expiratory conduit 114 may also be flexible (although perhaps to varying degrees) in any one or more of a dry state, an equilibrium state, and a saturated state. Because it is flexible, the expiratory conduit 114 may take a curved shape in use, as shown.

[0610] It has been found that, in use, the elongated tube 702 may not necessarily expand uniformly along its length between the connectors 706. That is, under conditional conditions, the diameter of the elongated tube 702 may not necessarily be uniform along its length. This may be because the concentration of water molecules within the lumen may vary along the length of the elongated tube 702. Such variation may be due to changes in one or more of the humidity of the respiratory gas (i.e., water vapor) and the accumulation of condensate (i.e., liquid water) along the length of the elongated tube 702. On the other hand, the partial pressure of water vapor in the ambient air outside the elongated tube 702 will be relatively constant along the length of the elongated tube 702.

[0611] In this example conditional state, local expansion of the elongated tube 702 may be observed in three different regions of the expiratory conduit 114, the inlet region 2704, the outlet region 2706, and the intermediate region 2708. In other examples, there may be two or more intermediate regions 2708. In still other examples, the elongated tube 702 may have local expansion in any one or more of the inlet region 2704, the outlet region 2706, and the one or more intermediate regions 2708. In still other examples, there may be no significant local expansion.

[0612] The local expansion area can be a portion of the length of the elongated tube 702 that has a larger diameter relative to the adjacent area (or multiple areas) of the elongated tube 702. In these areas, the elongated tube 702 can have a bulged appearance. The bulge can be tapered. In some examples, the local expansion can be easily apparent to the naked eye. In some examples, the maximum diameter of the local expansion area can be at least about 5%, at least about 10%, at least about 20%, or at least about 30% larger than in the adjacent area (or multiple areas) of the elongated tube 702 (e.g., for the outlet area 2706, the area between the outlet area 2706 and the intermediate area 2708).

[0613] It will be appreciated that the term "localized expansion" is not intended to mean that the expansion is limited to these areas. The term is used in a relative sense. That is, expansion in a localized expanded area may be more pronounced than expansion in adjacent areas.

[0614] When describing the inlet region 2704, the outlet region 2706, and the intermediate region 2708 below, the various ratios referring to the length of the elongated tube 702 refer to the length of the elongated tube 702 between the connectors 706, e.g., excluding the sleeve portion 1002 within the connector 706. It will be appreciated that the sum of these lengths will not exceed 100% of the length of the elongated tube 702 between the connectors 706. In some examples, the sum of the lengths of the inlet region 2704, the outlet region 2706, and the intermediate region 2708 may be less than about 75%, less than about 50%, or less than about 33% of the total length of the elongated tube 702 between the connectors 706.

[0615] The entry region 2704 may be within or correspond to a portion of the length of the elongated tube 702 that is closest to one or more of the Y-piece 110, the patient interface (not shown), and the patient (not shown). In some examples, the entry region 2704 may be up to about 50%, up to about 33%, up to about 25%, up to about 20%, or up to about 10% of the length of the elongated tube.

[0616] It has been discovered that at least one of the relative humidity of the breathing gases and the volume of condensate within the lumen of the elongated tube 702 can be elevated in the inlet region 2704 relative to one or more other regions of the elongated tube 702. For example, relative to a region intermediate the inlet region 2704 and the intermediate region 2708, or relative to a region intermediate the intermediate region 2708 and the outlet region 2706. For example, elevated relative humidity can be due to dehumidification of the breathable material as the breathing gases pass along the length of the lumen. For example, elevated condensate volume can be due to condensate from the Y-piece 110 or further upstream of the Y-piece (e.g., from the catheter mounting, patient interface, and patient ( Fig. 27 (not shown)) is directed into the inlet region 2704. At least some of this condensate can accumulate within the corrugations of the elongated tube 702 in the inlet region 2704.

[0617] The outlet region 2706 may be within or correspond to a portion of the length of the elongated tube 702 that is closest to one or more of the filter 2702, the gas return inlet 140, and the gas source 102. In some examples, the outlet region 2706 may be up to about 50%, up to about 33%, up to about 25%, up to about 20%, or up to about 10% of the length of the elongated tube.

[0618] It has been discovered that at least one of the relative humidity of the breathing gas and the volume of condensate within the lumen of the elongated tube 702 may be elevated in the outlet region 2706 relative to one or more other regions of the elongated tube 702. For example, relative to a region intermediate the inlet region 2704 and the intermediate region 2708, or relative to a region intermediate the intermediate region 2708 and the outlet region 2706. For example, the elevated relative humidity or volume of condensate may be due to condensate being drained from the filter 2702 or the gas source 102 into the outlet region 2706.

[0619] The intermediate region 2708 may be within a portion of the length of the elongated tube 702 that is intermediate the inlet region 2704 and the outlet region 2706. The intermediate region 2708 may be up to about 50%, up to about 33%, up to about 25%, up to about 20%, or up to about 10% of the length of the elongated tube.

[0620] It has been discovered that at least one of the relative humidity of the respiratory gas and the volume of condensate within the lumen of the elongated tube 702 may be increased in the intermediate region 2708 relative to one or more other regions of the elongated tube 702. For example, relative to a region intermediate the inlet region 2704 and the intermediate region 2708, or relative to a region intermediate the intermediate region 2708 and the outlet region 2706.

[0621] The flexibility of the expiratory conduit 114 means that the expiratory conduit 114 may tend to drape in a fold between the Y-piece 110 and the gas source 102. This draping may cause at least one low point 2710 to appear in the middle of the Y-piece 110 and the gas source 102. The low point 2710 may be located at a height lower than the end of the expiratory conduit 114 (e.g., lower than the Y-piece 110 and the gas return inlet 140). Any condensation in the lumen 1202 may tend to drain toward the low point 2710 due to gravity and accumulate there. This condensation may have formed in the elongated tube 702, or may have contributed to the conduit from other components of the respiratory assistance system 2700 (e.g., a conduit mount, a Y-piece, a connector, or a patient). The increased relative humidity or volume of the condensate in the intermediate region 2708 may be due to the accumulation of condensate at the low point 2710.

[0622] In some examples, it has been discovered that, in use, the conduit 700 may first exhibit localized expansion in the inlet region 2704. This may be followed later by localized expansion in one or more of the outlet region 2706 and the intermediate region 2708, for example as condensate begins to form in the filter 2702 or the gas source 102 and drain into the conduit 700. In some applications, periodic replacement of the filter 2702 may alleviate condensation in the filter and localized expansion in one or more of the outlet region 2706 and the intermediate region 2708.

[0623] Similarly, the expansion of the elongated tube 702 may not necessarily be uniform in one or more of the circumference and the wall thickness of the tube wall, such as in a cross section perpendicular to the longitudinal direction. For example, due to gravity, any condensation in the elongated tube 702 may accumulate at the lower region of the annular corrugation (i.e., the peak 1602 when viewed from outside the elongated tube 702). The elongated tube 702 may expand to a greater extent in this lower region than in the upper region of the corrugation. It should be understood that the lowest point of the corrugation in actual space is actually the "peak" of the corrugation when viewed in cross section or from outside the elongated tube.

[0624] It has been found that swelling of a breathable material can increase its permeability to water molecules when compared to a constrained breathable material under the same conditions. This may be due to the relatively large surface area of ​​the swollen breathable material.

[0625] The uneven expansion of the elongated tube 702 can advantageously increase the permeability of the elongated tube to water molecules where it is most needed. For example, one or more of the inlet region 2704, the outlet region 2706, and the intermediate region 2708. In use, the elongated tube 702 can automatically adapt to different or changing operating conditions. In contrast, the water trap is set in a fixed position (e.g., a midpoint) along the length of the conduit. As Fig. 27 As shown in , the midpoint or other fixed location may not necessarily coincide with the low point 2710 of the catheter, thereby significantly limiting its effectiveness.

[0626] manufacture

[0627] Fig.28 is a flow chart showing an example method 2800 for manufacturing a catheter 700 according to the present disclosure.

[0628] At step 2802, a continuous length of tubing suitable for use as elongated tube 702 may be produced by extruding a gas permeable material.

[0629] At step 2804, the extruded tubing may be at least partially corrugated by passing the semi-molten extruded tubing through a corrugator block. In some examples, portions of the extruded tubing may remain non-corrugated. These portions may become non-corrugated sleeve portions 1002. Alternatively, the entire extruded tubing may be corrugated.

[0630] At step 2806, the elongated tube 702 may be formed by cutting to length from the extruded and corrugated tubing. In some examples, the extruded and corrugated tubing may be cut at the non-corrugated portion. The cut may be made substantially centrally in the non-corrugated portion.

[0631] At step 2808, a sheath 704 may be disposed around the elongated tube 702. The elongated tube 702 may be inserted into the sheath 704. In some examples, the sheath 704 may have been previously cut to a predetermined length at step 2818. The sheath 704 may be cut from a roll of flattened braided tubular mesh sheath material. The sheath 704 may be cut to a length that is longer than the elongated tube 702 when deformed to conform to the exterior of the elongated tube 702, as described above.

[0632] At step 2810, the first connector component 1004 may be inserted into the first end of the elongated tube 702. In some examples, the first connector component 1004 may have been previously injection molded at step 2820.

[0633] At step 2812, the first connector component 1004, the first end of the elongated tube 702, and the corresponding first end of the sheath 704 may be clamped together within a mold tool. The mold tool may have protrusions to hold the first end of the sheath 704 so that it covers the first end of the elongated tube 702. In some examples, the mold tool may have opposing pairs of protrusions.

[0634] At step 2814, molten plastic material can be injected into the mold tool to form the second connector component 1006. That is, the second connector component 1006 can be overmolded onto the first connector component 1004, the first end of the elongated tube 702, and the first end of the sheath 704, thereby permanently fixing these components together. The orifice 1014 is formed by the molten plastic material flowing around the protrusions, which clamp the elongated tube 702 and the sheath 704 in place. Once the molten plastic material cools and solidifies, the connector 706 is completed and can be ejected from the mold.

[0635] Steps 2810 to 2814 may be repeated, or those same steps may be repeated simultaneously, to form a second connector 706 at the opposite second end of the catheter 700. The sheath 704 may first be contracted in the longitudinal direction at step 2816 so that its ends coincide with and cover the corresponding ends of the elongated tube 702, thereby creating a gap 1502. In some examples, the connectors 706 of the catheter 700 may be identical. In other examples, the connectors at the opposite ends of the catheter may be different from each other. In some examples, only one of the first connector component 1004 and the second connector component 1006 may be different between the two connectors 706. In other examples, both connector components may be different.

[0636] In other examples, the second connector component 1006 can be injection molded separately.For example, the second connector component 1006 can be attached to the first connector component 1004 by welding, adhesive or interference fit (eg, snap fit).

[0637] Glossary

[0638] "Breathable material" refers to a non-porous permeable material that allows water molecules to pass through the integral wall of the permeable material via a solution-diffusion mechanism, but does not allow bulk liquid water to pass through the wall or bulk respiratory gas flow through the wall. It will be understood by those skilled in the art that the water molecules in the wall are dispersed in a medium as molecules, and therefore have no state (solid, liquid or gas), although they are sometimes referred to as vapor in the art (e.g., the transmission rate is often referred to as moisture vapor transmission rate (MVTR) or the like). It will be further understood that the integral wall does not contain open channels or pores from one major surface to another major surface, such that pathogens can be carried through such channels with air or liquid water droplets via a pore flow mechanism. However, this definition is not intended to exclude tubes formed from such breathable materials, which tubes may have one or more holes disposed through the material, such as may be caused by, for example, a manufacturing defect, which may produce a negligible pore flow that does not have a substantial impact on the overall performance of the tube and the compliance and leakage requirements of ISO 5367:2014. It should be further understood that, like all polymers, some small molecule transport of respiratory gases (e.g., oxygen, carbon dioxide, nitrogen, or helium) may occur in trace or insignificant amounts (i.e., not a "bulk" flow), which for breathable materials as defined herein will typically occur at a rate that is at least an order of magnitude lower than that of water molecules. Moreover, of particular relevance to respiratory gases delivered to or from a patient, the amount of such small molecule transport of respiratory gases will be less than that allowed for compliance with relevant standards, such as in the leak test at Section 5.4 of ISO 5367:2014 (which is hereby incorporated by reference in its entirety), which is tested via the method set forth in Appendix E.

[0639] ISO Standard 4135:2001 (which is hereby incorporated by reference in its entirety) defines "compliance" at Section 3.1.5 as "the increase in volume per unit of pressure when a gas is added to a confined space, expressed at the temperature and humidity of the confined space at ambient atmospheric pressure" ( ISO 2001). The method for testing the compliance of a catheter according to the present disclosure is based on the method set forth in Appendix H of ISO 5367:2014 (which is incorporated by reference in its entirety). First, any leak in the catheter that is equal to or greater than 1 ml / min is sealed (as described in Appendix E). Second, the catheter is conditioned for at least one hour at 42±3°C and a relative humidity of not less than 80%. Third, one end of the catheter is sealed and the catheter is placed on a flat surface. Fourth, a pressure measuring device is connected to the opposite end of the catheter. Fifth, the catheter is inflated to a stable gauge pressure of 60±3 cmH2O for a period of five seconds or less, and the amount of air required is recorded. It will be appreciated that the constraints defined by the standard may not reflect the conditions in use, and that the standard was not drafted with breathable materials in mind. In order to better reflect the conditions in use, the compliance of a catheter formed at least in part by a breathable material may be further tested by additionally or alternatively constraining the catheter to an analogous conditional state as described below.

[0640] "Conditional" refers to the continuation of a state in which the elongated tube has been exposed to a water vapor pressure gradient, wherein the partial pressure of water vapor in the lumen is relatively high (i.e., higher than the water vapor partial pressure of ambient air) for a long period of time. That is, the wall of the elongated tube has absorbed water molecules from the lumen and may continue to absorb water molecules from the lumen. In particular, it can be said that a conduit that has been and continues to be used to transport a humidified respiratory gas flow for a period of time is in a conditional state. The wall of the elongated tube in a conditional state will therefore generally contain a higher concentration of water molecules than in a dry or equilibrium state, but generally lower than the concentration in a saturated state. References herein to certain properties of the conduit in "a" (singular) conditional state are not necessarily intended to apply to all conditional states, unless otherwise apparent from the context. In particular, depending on the design requirements and configuration of conduit parameters, the relative humidity and temperature of the respiratory gas and ambient air, and the concentration of water molecules in the permeable material of the elongated tube, the expansion of the elongated tube may or may not be constrained by the sheath in a specific conditional state. That is, in the continuation of the conditional state, there may be a subset of unconstrained conditional states and a subset of constrained conditional states. The conditional state can be analogized by constraining the catheter according to the following method. First, an ambient temperature of 22±2°C should be reached and maintained throughout the constraint method. Secondly, the catheter is laid in a V-shaped tray in a balanced state. Third, a gas flow is supplied to the lumen of the catheter at a flow rate of 10 standard liters per minute (SLPM) (referenced to 20°C, 101.325kPa), and the gas flow is humidified by a humidifier set to a humidity level of 37°C dew point and 100% relative humidity (RH) for a period of 24 hours.

[0641] "Constraint" refers to a non-negligible force applied by the sheath to the elongated tube, which acts to inhibit the expansion of at least a portion of the elongated tube in at least one of the longitudinal direction and the radial direction. The effect of the constraint may be limited to a portion of the tube when the tube transitions from an equilibrium state to a conditional state or from an unconstrained conditional state to a constrained conditional state. The elongated tube constrained by the sheath may be able to expand further, but any such expansion will require an expansion force that exceeds the constraining force applied by the sheath. That is, "constraint" is not intended to necessarily imply that any further expansion is completely prevented. Related terms "constrained", "constraint", "constraints", etc. will be interpreted accordingly. In contrast, "unconstrained" refers to the lack of force applied by the sheath to the elongated tube or the presence of a negligible force applied by the sheath to the elongated tube to resist the expansion of the elongated tube. For example, the force required to deform a sheath that is not subject to hoop stress (e.g., when the catheter is in equilibrium, the sheath is not subject to hoop stress, where there is a certain spacing between the elongated tube and the sheath) can be considered as "negligible force". The expansion of the elongated tube in the presence of such negligible force can be considered as "unconstrained by the sheath". Alternatively, it can be said that the elongated tube is able to expand "freely".

[0642] "Differential Scanning Calorimetry (DSC)" refers to the method based on ISO standard 11357-3:2018(E)( ISO, 2018) is a DSC test for melting point temperature performed on a test specimen of an elongated tube according to the method set forth in ISO 11357-1:2023, the entire contents of which are hereby incorporated by reference. In a first step, a test specimen is prepared according to ISO 11357-1:2023 (the entire contents of which are hereby incorporated by reference). Secondly, the test specimen is dried according to the drying method of ISO 62:2008 (E), as briefly described with respect to the second step of the immersion test method defined below. Thirdly, the apparatus is set up according to ISO 11357-1:2023, the test specimen is loaded into a crucible and inserted into the crucible. Fourthly, the test specimen is heated from a temperature of about -20°C to a temperature of about 250°C at a rate of about 10 degrees Celsius per minute (°C / min). Fifthly, the temperature is maintained for 5 minutes. Sixthly, the test specimen is cooled from about 250°C to a temperature of about -20°C at a rate of about -10°C / min. Seventhly, the temperature is maintained for 5 minutes. Eighth, the test sample is again heated from a temperature of about -20°C to a temperature of about 250°C at a rate of about 10°C / min while recording the differential thermal rate (measured in milliwatts per milligram (mW / mg)) of the sample. The differential thermal rate can be plotted versus temperature, and the melting point(s) of the test sample can be identified based on the temperature(s) corresponding to the peak(s) in the plot.

[0643] "Dry" refers to the state of an elongated tube or a sample thereof which has been dried according to the drying method of ISO 62:2008(E), as briefly described in relation to the second step of the immersion test method defined below. It is an "artificial" state in that the elongated tube will not normally enter such a state during normal use (e.g. when used in an assisted breathing system). The wall of the elongated tube in the dry state will generally contain a lower concentration of water molecules than in any of the equilibrium, conditional and saturated states.

[0644] "Equilibrium" refers to a state in which an elongated tube, which is generally free of condensation or other liquid water, has been exposed to ambient air (e.g., in a controlled environment with a relative humidity of 40% to 60%, both within the tube lumen and outside the tube wall) for a period of time sufficient for the elongated tube to reach a stable state. That is, the concentration of water molecules within the gas permeable material has reached equilibrium with the ambient air. The tube wall of the elongated tube in the equilibrium state will generally contain a higher concentration of water molecules than in a dry state, but generally a lower concentration than in a conditioned or saturated state. Depending on the configuration of the catheter parameters of the catheter, the environmental conditions (including the temperature and relative humidity of the ambient air), and the concentration of water molecules within the gas permeable material of the elongated tube, the expansion of the elongated tube may or may not be constrained by the sheath. However, in at least some examples, the catheter can be designed to have a certain spacing between the elongated tube and the sheath in the equilibrium state to allow at least some expansion of the elongated tube before the elongated tube is constrained by the sheath.

[0645] "Immersion test" refers to the test method used in accordance with ISO 62:2008(E) ( ISO, 2008) is a test to determine water absorption, which is incorporated herein by reference in its entirety. First, cut at least three tubular test specimens from an elongated tube into a length of 25±1 mm. These cuts should be made perpendicular to the longitudinal direction of the elongated tube. The cut edges should be smooth and free of cracks. The specimens should only include (multiple) active plastics responsible for the water absorption properties. If possible, the heating wire, sleeve and any mechanical support material should be removed in a non-destructive manner. Secondly, dry the specimens. The specimens can be dried in a convection oven or vacuum oven maintained at 50±2°C for at least 24 hours, or in a temperature of 60°C, a dew point of -40°C, and an air flow of 14 cubic meters per hour (m 3 / h) for 600 minutes (m) of drying time. The sample should be weighed to the nearest 1mg and returned to the oven / dryer regularly until its mass is constant to within ±1mg. Third, allow the sample to cool to room temperature in the dryer. Fourth, weigh the sample (m1) and measure the size. Fifth, soak the sample in distilled water for a period of 24 hours. There should be at least 8ml of distilled water per square centimeter of the total surface of the sample, and no less than 300ml for each sample. If necessary, the sample can be placed in a stainless steel wire basket connected to the anchor weight by stainless steel wire. Sixth, remove the sample from the water and wipe it with a lint-free cloth to remove the surface water. Seventh, within 1 minute of removing the sample from the water, weigh the sample to the nearest 1mg. Eighth, repeat the sixth step (immersion) and the seventh step (weighing) until the mass of the sample is constant to within ±1mg (m2). Ninth, if it is known or suspected that the sample contains appreciable amounts of water-soluble components, repeat step 2 (drying) and weigh the sample to correct for the water-soluble material lost during the immersion test. If the reconditioned mass is less than the conditioned mass, the difference represents the water-soluble material lost during the immersion test. According to the formula Alternatively, for samples containing water-soluble substances, The water absorption of each specimen is expressed as a percentage change of mass c relative to the initial mass. The results are expressed as the arithmetic mean of three (or more) values ​​obtained at the same exposure duration. References to immersion tests in this specification refer to tests performed on sample specimens of the gas-permeable material or elongated tube separately from the connector and sheath. That is, the connector and sheath are omitted or removed so that the expansion is not constrained by the sheath.

[0646] "ISO" refers to the International Organization for Standardization, and more specifically to the international standards defined by that organization. Those standards are protected by copyright and are available for purchase directly from the International Organization for Standardization at http: / / www.ISO.org.

[0647] "Leak", "leakage" and "leak test" refer to ISO 5367:2014 ( ISO2014) is hereby incorporated by reference in its entirety. This standard defines the limit of a complete breathing set supplied for use with a ventilator breathing system (VBS) or an anesthetic breathing system as 70 ml / min (expected delivery volume ≥ 300 ml) for adult patients, 40 ml / min (50 < 300 ml) for pediatric patients, or 30 ml / min (≤ 50 ml) for neonatal patients at a pressure of 60 ± 3 cmH2O. For a single breathing tube not intended for use with a VBS or an anesthetic breathing system, the leakage limit is 25 ml / min at 60 ± 3 cmH2O. In short, the leak is tested according to the standard by first constraining the catheter for at least one hour at a temperature of 23 ± 3 ° C. Secondly, one end of the catheter is closed. Third, an internal gas pressure of 60 ± 3 cmH2O is applied and maintained. Fourth, the air flow required to maintain the pressure is recorded. It will be appreciated that the constraints defined by the standard may not reflect in-use conditions and that the standard was not drafted with gas permeable materials in mind. To better reflect in-use conditions, conduits formed at least in part from gas permeable materials may be further tested for leakage by additionally or alternatively constraining the conduit to an analogous conditional state as described above.

[0648] "Long-term use," "extended use," "long term," etc. refers to the use of a catheter in a respiratory assistance system (or surgical insufflation system) to deliver heated and humidified breathing gases (or insufflation gases) for a continuous period of at least 24 hours. Long-term use can be analogized by the conditional states of the analogy described above.

[0649] "Flow resistance" and "flow resistance test" refer to ISO 5367:2014 ( ISO 2014) in Section 5.5 at Appendix F and the methods set out therein, the entire contents of which are hereby incorporated by reference in their entirety. This standard defines the flow resistance limits for catheters supplied ready for use as 0.06 cmH2O / l / min at a flow rate of 30 l / min for adult patients (expected delivery volume ≥ 300 ml), 0.12 cmH2O / l / min at a flow rate of 15 l / min for pediatric patients (50 < 300 ml), and 0.74 cmH2O / l / min at a flow rate of 2.5 l / min. In short, flow resistance is tested by first constraining the catheter at a temperature of 23 ± 3 ° C for at least one hour. Secondly, the flow rate of the flow control device is adjusted and maintained for 30 s, and the pressure is recorded. Thirdly, the catheter is assembled on the outlet of the buffer reservoir and the free end of the catheter is fixed, keeping the catheter straight. Fourth, the air flow is adjusted and maintained for 30 s again, and the pressure is recorded. Fifth, the pressure increase due to the catheter is calculated from the recorded pressure difference. The increase in resistance to flow with bending is tested by first constraining the catheter for at least one hour at a temperature of 42±3°C and a relative humidity of at least 80%. Secondly, the catheter is hung on a gas bottle with a diameter of 25 mm, and a tensile force is applied to maintain contact over more than half of the circumference of the gas bottle. Third, an air flow is applied and the pressure is recorded after five minutes. Fourth, the pressure increase due to the catheter is calculated from the pressure difference between the curved and straight catheters. It will be understood that the constraints defined in the standard may not reflect the conditions in use, and the standard was drafted without taking into account breathable materials. In order to better reflect the conditions in use, the resistance to flow of the catheter, which is at least partially formed by breathable materials, can be further tested by additionally or alternatively constraining the catheter to a conditional state of the analogy as described above.

[0650] "Saturated" refers to a state in which the elongated tube or a sample thereof has been subjected to an immersion test (i.e., immersed in liquid water) for a period of time until the permeable material absorbs no further water molecules or absorbs negligible amounts of water molecules. That is, until the combined mass of the permeable material and absorbed water molecules is at or near a maximum. It is an "artificial" state in that the elongated tube will not normally enter such a state during normal use (i.e., when used in an assisted breathing system). The tube wall of the elongated tube in the saturated state typically contains a higher concentration of water molecules than in any of the dry, equilibrium, and conditioned states.

[0651]

Explanation of symbols

[0652] 100: Breathing assistance system

[0653] 102: Gas source

[0654] 104: Humidifier supply duct

[0655] 106: Humidifier

[0656] 108: Suction catheter

[0657] 110:Y-shaped piece

[0658] 112: Patient joint

[0659] 114: Expiratory tube

[0660] 116: Pressure generator

[0661] 118: Gas inlet

[0662] 120: Gas source controller

[0663] 122: User Interface

[0664] 124: Gas source outlet

[0665] 126: Humidification Chamber

[0666] 128: Room Heater

[0667] 130: Humidifier controller

[0668] 132: User Interface

[0669] 134: Heating wire

[0670] 136:Sensor probe

[0671] 138: Sensor lead

[0672] 140: Gas return inlet

[0673] 142: Breathing Circuit

[0674] 144: Inspiratory branch

[0675] 146: Expiratory limb

[0676] 200: Breathing assistance system

[0677] 202: Heating wire

[0678] 204:Sensor

[0679] 206:Electric and pneumatic connector

[0680] 208:Supplementary gas inlet

[0681] 302: Heater base

[0682] 304: Box

[0683] 306: Touch screen display

[0684] 308: Switch

[0685] 310: Indicator light

[0686] 312: Release button

[0687] 400: Breathing assistance system

[0688] 402: Pressure regulator

[0689] 404: Liquid

[0690] 406: Entry probe

[0691] 408: Pressure relief valve

[0692] 500: Breathing assistance system

[0693] 502: Blower

[0694] 504: Respiratory therapy devices

[0695] 506: Shell

[0696] 600:Surgical Insufflation System

[0697] 602: Insufflator supply catheter

[0698] 604:Insufflator

[0699] 606: Delivery catheter

[0700] 608:Surgical Intubation

[0701] 610: Smoke exhaust system

[0702] 612: Wall mounted source

[0703] 614: Gas cylinders for compressed gas

[0704] 616: Discharge duct

[0705] 618: Emission filter

[0706] 620: Vacuum source

[0707] 622: Additional discharge conduit

[0708] 624: Blowing into the circuit

[0709] 626: Looking Glass

[0710] 628: Laparoscopic Monitor

[0711] 700: Catheter

[0712] 702: Long tube

[0713] 704: Sheath

[0714] 706: Connector

[0715] 802: Hole

[0716] 902: Vertical direction

[0717] 904: Clockwise knitting element

[0718] 906: Counterclockwise knitting element

[0719] 908: Opening

[0720] 1002: casing part

[0721] 1004: First connector component

[0722] 1006: Second connector component

[0723] 1008: Chamfered edge

[0724] 1010: Flange

[0725] 1012: Ring Channel

[0726] 1014: Orifice

[0727] 1016: corrugated part

[0728] 1102: tapered conical end

[0729] 1202: Lumen

[0730] 1502: Interval

[0731] 1504: Radial direction

[0732] 1602: Peak

[0733] 1604: Valley

[0734] 1702: Line

[0735] 1704: Melting point

[0736] 1802: Filament

[0737] 2102:Central part

[0738] 2104: End portion

[0739] 2106: cone

[0740] 2108: Unsheathed Catheter

[0741] 2202: Ripple

[0742] 2204: Side wall

[0743] 2206: Force Vector

[0744] 2402: Depth

[0745] 2602: Internally narrowed waist area

[0746] 2604: Externally narrowed waist area

[0747] 2700:Respiratory Assistance System

[0748] 2702:Filter

[0749] 2704:Entrance area

[0750] 2706:Exit Area

[0751] 2708: Middle Area

[0752] 2710: Low point

[0753] 2800:Method of forming a catheter

[0754] 2802: Extrusion step

[0755] 2804: Ripple Processing Steps

[0756] 2806: Tube cutting steps

[0757] 2808:Connection Steps

[0758] 2810:Connector Insertion Steps

[0759] 2812: Clamping steps

[0760] 2814: Connector overmolding steps

[0761] 2816: Sheath shrinking step

[0762] 2818: Sheath cutting steps

[0763] 2820: Connector Molding Steps

Claims

1. A medical gas conduit for a medical gas system, the medical gas conduit comprising: an elongated tube defining a lumen for flow of a medical gas therethrough, at least a portion of the elongated tube comprising a gas permeable material configured, in use, to swell due to absorption of water molecules; as well as A sheath is disposed around at least a portion of the elongated tube, wherein the sheath is configured to restrict expansion of at least a portion of the elongated tube in at least one of a radial direction and a longitudinal direction due to absorption of water molecules by the air-permeable material during use.

2. A medical gas conduit for a medical gas system, the medical gas conduit comprising: An elongated tube defining a lumen for flowing a medical gas therethrough, at least a portion of the elongated tube being corrugated and comprising: a breathable material configured to swell in use due to absorption of water molecules, and multiple ripples; and a sheath disposed around at least a portion of the elongated tube and configured to restrict expansion of the elongated tube at least in a longitudinal direction of the elongated tube during use; The elongated tube is configured such that the spacing between the plurality of corrugations changes during use depending on the absorption of water molecules by the breathable material and the constraint of the sheath on the elongated tube.

3. A medical gas conduit for a medical gas system, the medical gas conduit comprising: an elongated tube defining a lumen for flow of a medical gas therethrough, at least a portion of the elongated tube comprising a gas permeable material configured, in use, to swell due to absorption of water molecules; as well as A sheath is disposed around at least a portion of the elongated tube, with each end of the sheath being secured to a corresponding end of the elongated tube, wherein the sheath is configured such that, in use, a length and a diameter of the sheath change in inverse relationship to each other as the breathable material expands due to absorption of water molecules.

4. A medical gas conduit for a medical gas system, the medical gas conduit comprising: an elongated tube defining a lumen for flowing a medical gas therethrough; a sheath disposed around at least a portion of the elongated tube; as well as A pair of connectors for pneumatically coupling the elongated tube to other components of the respiratory system, each connector of the pair of connectors securing a respective end of the sheath relative to a corresponding end of the elongated tube, and at least a first connector of the pair of connectors including a plurality of apertures through which one or more of the elongated tube and the sheath are exposed.

5. A medical gas conduit for a medical gas system, the medical gas conduit comprising: an elongated tube defining a lumen for flowing a medical gas therethrough, and a sheath disposed around at least a portion of the elongated tube, Wherein, the sheath is configured to be at least partially spaced apart from a maximum outer diameter of the elongated tube when the medical gas conduit is in an equilibrium state.

6. A medical gas conduit for a medical gas system, the medical gas conduit comprising: an elongated tube defining a lumen for flowing a medical gas therethrough, at least a portion of the elongated tube comprising a gas permeable material configured, in use, to expand upon absorbing water molecules; as well as a sheath disposed around at least a portion of the elongated tube and configured to selectively restrict expansion of the elongated tube due to absorption of water molecules during use; Wherein, the elongated tube and the sheath are configured such that compliance of the medical gas conduit under at least some conditions depends on a physical interaction between the elongated tube and the sheath.

7. A medical gas conduit for a medical gas system, the medical gas conduit comprising: an elongated tube defining a lumen for flowing a medical gas therethrough, at least a portion of the elongated tube comprising a gas permeable material configured, in use, to expand upon absorbing water molecules; as well as a sheath loosely disposed around at least a portion of the elongated tube; Wherein, the elongated tube is configured to apply hoop stress to the jacket under at least some conditions during use.

8. A medical gas conduit for a medical gas system, the medical gas conduit comprising: an elongated tube defining a lumen for flowing a medical gas therethrough; as well as A sheath is disposed around at least a portion of the elongated tube, the sheath comprising a braided tubular mesh including a biaxial braid of a plurality of braided elements spaced apart around a periphery of the sheath and extending helically around the elongated tube, and the plurality of braided elements each comprising a pair of adjacent filaments.

9. A medical gas conduit for a medical gas system, the medical gas conduit comprising: An elongated tube defining a lumen for passing a flow of a medical gas, at least a portion of the elongated tube comprising a gas permeable material, at least a portion of the elongated tube being configured to absorb between about 100% and 250%, preferably between about 100% and 180%, more preferably between about 110% and 150%, still more preferably between about 120% and 140% or between about 130% and 145%, and still more preferably between about 135% and 145%, for example about 138% or 139%, of its own dry mass in an immersion test.

10. A medical gas conduit for a medical gas system, the medical gas conduit comprising: An elongated tube defining a lumen for passing a flow of medical gas therethrough, at least a portion of the elongated tube comprising a gas permeable material, at least a portion of the elongated tube being configured to absorb between about 40% and 80%, preferably between about 40% and 60%, more preferably between about 45% and 55%, and still more preferably between about 48% and 51%, for example about 49%, of its own dry mass in an immersion test, and the medical gas conduit does not include a heating wire.

11. A medical gas conduit for a medical gas system, the medical gas conduit comprising: an extruded elongated tube defining a lumen for flowing a medical gas therethrough, at least a portion of the elongated tube comprising a gas permeable material; as well as a pair of connectors at respective ends of the elongated tube for pneumatically coupling the medical gas conduit with other components of the medical gas system, at least one of the pair of connectors comprising: a first connector component at least partially inserted into the lumen of the elongated tube, and A second connector component is overmolded to the first connector component and the elongated tube.

12. A medical gas conduit for a medical gas system, the medical gas conduit comprising: An elongated tube defining a lumen for passing a medical gas flow therethrough, at least a portion of the elongated tube comprising a gas permeable material, the gas permeable material comprising two melting points in a differential scanning calorimetry (DSC) test, each melting point having a temperature above about 197°C, preferably above about 202°C, more preferably above about 204°C, still more preferably above about 205°C, and most preferably above about 206°C, for example a temperature equal to or above about 207°C, wherein the medical gas conduit does not include a heating wire.

13. A medical gas conduit for a medical gas system, the medical gas conduit comprising: An elongated tube defining a lumen for flowing a medical gas therethrough, at least a portion of the elongated tube comprising a gas permeable material comprising three melting points in a differential scanning calorimetry (DSC) test, wherein the medical gas conduit does not include a heating wire.

14. A medical gas conduit for a medical gas system, the medical gas conduit comprising: An elongated tube defining a lumen for passing a flow of a medical gas, at least a portion of the elongated tube comprising a gas permeable material, the gas permeable material comprising a minimum melting point in a differential scanning calorimetry (DSC) test, the minimum melting point having a temperature greater than about 37°C, preferably greater than about 42°C, more preferably greater than about 44°C, still more preferably greater than about 45°C, and most preferably greater than about 46°C, for example at a temperature of about 47°C.

15. A medical gas conduit for a medical gas system, the medical gas conduit comprising: An elongated tube defining a lumen for flowing a medical gas therethrough, at least a portion of the elongated tube comprising a gas permeable material configured to swell in use due to absorption of water molecules, wherein the medical gas conduit is configured such that in use in at least one conditional state the elongated tube has a localized swelling in one or more of the following: an inlet region, the inlet region being closest to a patient interface of the medical gas system and comprising up to about 50%, preferably up to about 33%, more preferably up to about 25%, still more preferably up to about 20%, and most preferably up to about 10% of the length of the elongate tube; an outlet region that is closest to a gas return inlet of a gas source of the medical gas system and includes up to about 50%, preferably up to about 33%, more preferably up to about 25%, even more preferably up to about 20%, and most preferably up to about 10% of the length of the elongated tube; and An intermediate region, which is intermediate between the inlet region and the outlet region and includes up to about 50% of the length of the elongated tube, preferably up to about 33%, more preferably up to about 25%, still more preferably up to about 20%, and most preferably up to about 10%.

16. A medical gas conduit according to any one of claims 9 to 15, comprising a sheath arranged around at least a portion of the elongate tube.

17. The medical gas conduit according to any one of claims 4 to 5 and 8, the elongate tube comprising a gas permeable material.

18. The medical gas conduit of any one of claims 1 to 17, the medical gas conduit comprising an expiratory conduit, the medical gas system comprising a respiratory assistance system, and the medical gas flow comprising a respiratory gas flow.

19. The medical gas conduit of any one of claims 1 to 17, the medical gas conduit comprising an inspiratory conduit, the medical gas system comprising a respiratory assistance system, and the medical gas flow comprising a respiratory gas flow.

20. The medical gas conduit of any one of claims 1 to 17, the medical gas conduit comprising an exhaust conduit, the medical gas system comprising a surgical insufflation system, and the medical gas flow comprising an insufflation gas flow.

21. A medical gas conduit according to any one of claims 1 to 20, configured such that the diameter and length of at least one, and preferably both, of the elongate tube and the sheath can be temporarily varied in use.

22. The medical gas conduit according to any one of claims 1 to 21, wherein: The length and diameter of the sheath are configured to change in an inverse relationship when the elongated tube expands due to absorption of water molecules during use.

23. The medical gas conduit according to any one of claims 1 to 22, wherein: The sheath has a length to diameter gradient of between about -100 and -20, preferably between about -50 and -20, more preferably between about -40 and -35, and most preferably about -37.

24. The medical gas conduit according to any one of claims 1 to 22, wherein: The sheath has a length to diameter gradient of between about -75 and -25, preferably between about -60 and -40, more preferably between about -55 and -45, and most preferably about -52.

25. The medical gas conduit according to any one of claims 1 to 24, wherein: The length and diameter gradient of the sheath is substantially linear when the diameter of the sheath is between about 24 mm and 32 mm.

26. A medical gas conduit according to any one of claims 1 to 25, wherein: The sheath, in a separated condition, is configured to conform to a rod having an outer diameter ranging between about 23 mm and 43 mm.

27. A medical gas conduit according to any one of claims 1 to 26, the sheath comprising a plurality of openings, preferably quadrilateral openings, arranged to undergo an affine transformation in use when the elongate tube expands due to absorption of water molecules by the gas permeable material.

28. A medical gas conduit according to any one of claims 1 to 27, wherein: The sheath is configured to be at least partially spaced apart from the elongate tube when the medical gas conduit is in at least one of a dry state and an equilibrium state, and preferably both.

29. A medical gas conduit according to any one of claims 1 to 28, wherein: When in use and in any one or more of a dry state, an equilibrium state, and at least one conditional state, the elongated tube and the sheath are configured such that in at least one section through the medical gas conduit, the sheath is spaced outwardly from at least a portion of the periphery of the elongated tube.

30. A medical gas conduit according to any one of claims 1 to 29, wherein: The elongated tube and the jacket are configured such that the elongated tube applies a hoop stress to the jacket when in use in at least one conditional state.

31. A medical gas conduit according to any one of claims 1 to 30, wherein: In use, in at least one conditional state, the elongate tube and the sheath are configured such that in at least one cross section through the medical gas conduit, the sheath contacts the entire circumference of the elongate tube.

32. A medical gas conduit according to any one of claims 1 to 31, wherein: The breathable material is unfoamed.

33. A medical gas conduit according to any one of claims 1 to 31, wherein: The breathable material is foamed.

34. A medical gas conduit according to any one of claims 1 to 33, wherein the gas permeable material comprises a block copolymer, preferably a block copolymer comprising one or more of: a hard segment of polybutylene terephthalate; and The soft segment of ether-type macroethylene glycol.

35. A medical gas conduit according to claim 34, wherein the block copolymer comprises at least about 90%, preferably at least about 92%, more preferably at least about 95%, and more preferably at least about 97%, for example about 97% or about 98.5%, of the breathable material by one or more of mass, weight and volume.

36. A medical gas conduit according to any one of claims 1 to 35, wherein the gas permeable material comprises one or more additives, such as one or more of the following: Foaming agent, Colorants, Ultraviolet (UV) stabilizers, UV absorbers, and Processing aids.

37. A medical gas conduit according to claim 36, wherein the one or more additives comprise up to about 10%, preferably up to about 8%, more preferably up to about 5%, and most preferably up to about 3%, for example about 3% or about 2%, of the permeable material by one or more of mass, weight and volume.

38. A medical gas conduit according to any one of claims 1 to 37, wherein: At least a portion of the elongated tube is configured to absorb more than about 33% of its own dry mass, more preferably between about 33% and 200%, even more preferably between about 100% and 160%, even more preferably between about 120% and 140%, and most preferably between about 130% and 135%, for example about 133%, of water molecules in an immersion test.

39. A medical gas conduit according to any one of claims 1 to 38, wherein: At least a portion of the elongated tube is configured to absorb between about 45% and 250% of its own dry mass in an immersion test, preferably between about 65% and 200%, more preferably between about 75% and 175%, even more preferably between about 100% and 160%, even more preferably between about 110% and 150%, even more preferably between about 120% and 140%, even more preferably between about 130% and 140%, and most preferably between about 133% and 139%, for example about 139%, of water molecules.

40. A medical gas conduit according to any one of claims 1 to 39, wherein: During an immersion test, when separated from the sheath, at least a portion of the elongated tube is configured to expand during an immersion test by between about 20% and 70%, preferably between about 25% and 50%, and more preferably between about 30% and 50%, for example about 32%, in one or more of the radial direction, the longitudinal direction and the wall thickness, and preferably in each.

41. A medical gas conduit according to any one of claims 1 to 40, wherein: During the immersion test, when separated from the sheath, at least a portion of the elongated tube is configured to undergo one or more and preferably all of the following: expansion in said radial direction by between about 37% and 47%, preferably by about 42%; expands in said longitudinal direction by between about 32% and 42%, preferably by about 37%; and / or The wall thickness expands by between about 29% and 39%, preferably about 34%.

42. A medical gas conduit according to any one of claims 1 to 41, comprising a pair of connectors at opposite ends of the medical gas conduit, the pair of connectors being configured to pneumatically couple the elongated tube to other components of the medical gas system, at least one of the pair of connectors comprising a first connector part and a second connector part, wherein The corresponding ends of the elongated tube and the sheath are fixed between the first connector component and the second connector component.

43. The medical gas conduit of claim 42, the first connector component extending into the lumen of the elongate tube.

44. A medical gas conduit according to claim 42 or 43, wherein The second connector component is overmoulded to one or more and preferably all of the first connector component, the elongate tube and the sheath.

45. A medical gas conduit according to any one of claims 42 to 44, the second connector part comprising a plurality of apertures, preferably between two and six apertures, such as four apertures, through which the elongate tube and the sheath are exposed.

46. ​​A medical gas conduit according to any one of claims 42 to 45, wherein: the end of the elongated tube being disposed substantially concentrically around a portion of the first connector member; The end of the sheath is disposed substantially concentrically around the end of the elongated tube; as well as The second connector component is disposed substantially concentrically about the end of the sheath.

47. A medical gas conduit according to any one of claims 42 to 46, wherein: At least one of the first connector component and the second connector component is at least partially formed from one or more of polycarbonate, polypropylene, and polyethylene.

48. A medical gas conduit according to any one of claims 42 to 47, wherein At least one of the pair of connectors is configured to prevent or inhibit expansion of an end portion of the elongated tube secured between the first connector component and the second connector component.

49. A medical gas conduit according to any one of claims 42 to 48, wherein The elongated tube and the sheath are not fixed to each other in the middle of the pair of connectors.

50. A medical gas conduit according to any one of claims 42 to 49, wherein The catheter is configured such that the elongate tube tapers towards at least one, and preferably both, of the pair of connectors when in use in at least one conditional state.

51. A medical gas conduit according to any one of claims 42 to 50, wherein The catheter is configured such that the sheath tapers toward at least one, and preferably both, of the pair of connectors when in at least one, and preferably both, of an equilibrium state and a conditional state.

52. A medical gas conduit according to any one of claims 1 to 51, wherein: The medical gas conduit is configured such that, in use: Upon initial absorption of water molecules, the elongated tube is configured to expand relatively unconstrained by the sheath, and Upon further absorption of water molecules, the elongated tube is configured to expand while being relatively constrained by the sheath.

53. The medical gas conduit of claim 52, wherein: The elongated tube is configured to expand after prolonged use while being relatively restrained by the sheath.

54. A medical gas conduit according to any one of claims 1 to 53, wherein: The sheath configuration is: The sheath does not restrict expansion of the elongated tube when the elongated tube is in a balanced state in use; and The sheath restrains expansion of the elongate tube when the elongate tube is in at least one conditional state in use.

55. A medical gas conduit according to any one of claims 1 to 54, wherein The medical gas conduit is configured such that, in use: Upon initial absorption of water molecules, the elongated tube is configured to expand in the radial direction relatively unconstrained by the sheath, and Upon further absorption of water molecules, the elongated tube is configured to further expand in the radial direction while being relatively constrained by the sheath.

56. A medical gas conduit according to any one of claims 1 to 55, wherein The sheath configuration is: When the elongated tube is in a balanced state, the sheath does not restrict the expansion of the elongated tube in the radial direction; and The sheath constrains expansion of the elongated tube in the radial direction when the elongated tube is in at least one conditional state in use.

57. A medical gas conduit according to any one of claims 1 to 56, wherein: The medical gas conduit is configured such that, in use: Upon initial absorption of water molecules, the elongated tube is configured to expand in the longitudinal direction relatively unconstrained by the sheath; and Upon further absorption of water molecules, the elongated tube is configured to expand in the longitudinal direction while being relatively constrained by the sheath.

58. The medical gas conduit of claim 57, wherein: The medical gas conduit is configured such that upon further absorption of water molecules in use, the elongate tube is configured to expand in the radial direction, and the sheath is configured to at least partially collapse the medical gas conduit in the longitudinal direction.

59. A medical gas conduit according to any one of claims 1 to 58, wherein The sheath is configured to not restrict expansion of the elongated tube in the longitudinal direction in a balanced state, and to restrict expansion of the elongated tube in the longitudinal direction in at least one conditional state.

60. The medical gas conduit according to any one of claims 1 to 59, wherein: The medical gas conduit is configured such that, in use: Upon initial absorption of water molecules, the elongated tube is configured to expand freely in the radial direction and the longitudinal direction, and Upon further absorption of water molecules, the elongated tube is configured to engage the sheath, and further expansion is constrained in at least one of the radial direction and the longitudinal direction.

61. A medical gas conduit according to any one of claims 1 to 60, wherein: The sheath is configured to allow the elongated tube to expand freely in the radial direction and the longitudinal direction in a balanced state, and is configured to restrict expansion of the elongated tube in at least one of the radial direction and the longitudinal direction in at least one conditional state.

62. A medical gas conduit according to any one of claims 1 to 61, wherein The medical gas conduit is configured such that, in use: Upon initial absorption of water molecules, the elongated tube is configured to freely expand in a radial direction to engage the inner surface of the sheath, and Upon further absorption of water molecules, the elongated tube is configured to further expand in the radial direction, thereby causing the sheath to expand in the radial direction and contract in the longitudinal direction.

63. A medical gas conduit according to any one of claims 1 to 62, wherein: The elongated tube and the sheath are configured such that expansion of the elongated tube in the radial direction causes the elongated tube to engage the sheath and causes the sheath to expand in the radial direction and contract in the longitudinal direction.

64. A medical gas conduit according to any one of claims 1 to 63, wherein: The elongated tube is configured to have: a first length before use; a second length when initially absorbing water molecules; and a third length when further absorbing water molecules, wherein the second length is longer than the first length and the third length.

65. A medical gas conduit according to any one of claims 1 to 64, wherein The elongated tube is configured to have: a first length in a balanced state; a second length in at least one conditional state, in which the radial expansion of the elongated tube is not constrained by the sheath; and a third length in at least one other conditional state, in which the radial expansion of the elongated tube is constrained by the sheath, wherein the second length is longer than the first length and the third length.

66. A medical gas conduit according to claim 64 or 65, wherein The third length is within about 90% to 110% of the first length, and is preferably about equal to the first length.

67. The medical gas conduit of any one of claims 1 to 66, the elongated tube comprising a plurality of corrugations.

68. The medical gas conduit of claim 67, wherein The medical gas conduit is configured such that, in use, the profile of each of the plurality of corrugations changes as the elongate tube expands due to absorption of water molecules.

69. A medical gas conduit according to claim 67 or 68, wherein The plurality of corrugations are each defined in part by a pair of side walls, and the elongate tube and jacket are configured such that the side walls reorient themselves, preferably towards the radial direction, when the elongate tube absorbs water molecules in use.

70. The medical gas conduit of claim 69, wherein: The sidewalls are configured to redirect beyond a radial direction as the elongated tube continues to absorb water molecules.

71. A medical gas conduit according to any one of claims 67 to 70, wherein The medical gas conduit is configured such that: when the elongated tube is in at least one of a dry state and an equilibrium state, the spacing of the plurality of corrugations is substantially uniform along the length of the elongated tube; and when the elongated tube is in at least one conditional state, the spacing of the plurality of corrugations varies along the length of the elongated tube.

72. The medical gas conduit of any one of claims 1 to 71, the elongate tube comprising a sleeve portion at an end of the elongate tube, wherein: The sleeve portion is non-corrugated.

73. The medical gas conduit of any one of claims 1 to 72, the sheath comprising a tubular mesh, preferably a braided tubular mesh.

74. The medical gas conduit of any one of claims 1 to 73, the sheath comprising a biaxial braid of a plurality of braid elements, each braid element extending helically around the elongate tube.

75. The medical gas conduit of claim 74, wherein each of the plurality of braided elements comprises two or three filaments.

76. The medical gas conduit of claim 74 or 75, the sheath comprising at least one of: Between about 75 and 125 knitting elements, preferably between about 90 and 100 knitting elements, for example about 96 knitting elements; and Between about 150 and 250 filaments, and preferably between about 180 and 200 filaments, for example about 192 filaments.

77. A medical gas conduit according to any one of claims 1 to 76, wherein: The elongated tube is configured as follows: having a substantially uniform diameter in at least one of a dry state and an equilibrium state; and Having a substantially non-uniform diameter in at least one conditional state in use.

78. The medical gas conduit according to any one of claims 1 to 77, wherein: The medical gas conduit is configured such that in use, in at least one conditional state, the elongate tube has a localised expansion in one or more regions where the relative humidity or volume of condensate within the lumen is elevated.

79. The medical gas conduit according to any one of claims 1 to 78, wherein The medical gas conduit is an expiratory conduit configured such that, in a conditional state in use, the elongate tube has a localised expansion in one or more of the following: an inlet region, the inlet region being closest to a patient interface of the medical gas system and comprising up to about 50%, preferably up to about 33%, more preferably up to about 25%, still more preferably up to about 20%, and most preferably up to about 10% of the length of the elongate tube; an outlet region, the outlet region being closest to a gas return inlet of a gas source of the medical gas system and comprising up to about 50%, preferably up to about 33%, more preferably up to about 25%, even more preferably up to about 20%, and most preferably up to about 10% of the length of the elongated tube; as well as An intermediate region, which is intermediate between the inlet region and the outlet region and includes up to about 50% of the length of the elongated tube, preferably up to about 33%, more preferably up to about 25%, still more preferably up to about 20%, and most preferably up to about 10%.

80. The medical gas conduit according to any one of claims 1 to 79, wherein the gas permeable material comprises a minimum melting point in a differential scanning calorimetry (DSC) test, the temperature of the minimum melting point being greater than about 37°C, preferably greater than about 42°C, more preferably greater than about 44°C, more preferably greater than about 45°C, and most preferably greater than about 46°C, for example at a temperature of about 47°C.

81. A medical gas conduit according to any one of claims 1 to 80, wherein the gas permeable material comprises a minimum melting point in a DSC test, the temperature of the minimum melting point being between about 37°C and 100°C, preferably between about 40°C and 60°C, and more preferably between about 40°C and 50°C, for example at a temperature of about 47°C.

82. The medical gas conduit according to any one of claims 1 to 81, wherein the gas permeable material comprises a melting point in a differential scanning calorimetry (DSC) test, the melting point having a temperature between about 42°C and 52°C, preferably between about 44°C and 50°C, more preferably between about 45°C and 49°C, and still more preferably between about 46°C and 47°C, for example at a temperature of about 47°C.

83. The medical gas conduit according to any one of claims 1 to 82, wherein the gas permeable material comprises two melting points in a differential scanning calorimetry (DSC) test, and the temperatures of the two melting points are higher than about 197°C, preferably higher than about 202°C, more preferably higher than about 204°C, even more preferably higher than about 205°C, and most preferably higher than about 206°C, for example a temperature equal to or higher than about 207°C.

84. The medical gas conduit according to any one of claims 1 to 83, wherein the gas permeable material comprises two melting points in a differential scanning calorimetry (DSC) test, the temperatures of the two melting points being between about 202°C and 225°C, preferably between about 204°C and 223°C, more preferably between about 205°C and 222°C, and still more preferably between about 206°C and 221°C, for example at a temperature of about 207°C and 220°C.

85. The medical gas conduit according to any one of claims 1 to 84, wherein the gas permeable material comprises two melting points in a differential scanning calorimetry (DSC) test, and the temperature difference between the two melting points is less than about 23°C, preferably less than about 18°C, more preferably less than about 16°C, even more preferably less than about 15°C, and most preferably less than about 14°C, for example, the temperature difference is about 13°C.

86. The medical gas conduit according to any one of claims 1 to 85, wherein the gas permeable material comprises two melting points in a differential scanning calorimetry (DSC) test, and the temperature difference between the two melting points is between about 150°C and 170°C, preferably between about 155°C and 165°C, more preferably between about 158°C and 162°C, and even more preferably between about 159°C and 161°C, for example, the temperature difference is about 160°C.

87. The medical gas conduit according to any one of claims 1 to 86, wherein the gas permeable material comprises three melting points in a differential scanning calorimetry (DSC) test, and the temperatures of the three melting points are between about 42°C and 225°C, more preferably between about 44°C and 223°C, still more preferably between about 45°C and 222°C, and most preferably between about 46°C and 221°C.

88. The medical gas conduit of any one of claims 1 to 87, the gas permeable material comprising one or more melting points in a differential scanning calorimetry (DSC) test, the one or more melting points having a temperature of at least one, and preferably all three, of the following: between about 42°C and 52°C, preferably between about 44°C and 50°C, more preferably between about 45°C and 49°C, and still more preferably between about 46°C and 47°C, for example at a temperature of about 47°C; Between about 202°C and 212°C, preferably between about 204°C and 210°C, more preferably between about 205°C and 209°C, and still more preferably between about 206°C and 208°C, for example at a temperature of about 207°C; and Between about 215°C and 225°C, preferably between about 217°C and 223°C, more preferably between about 218°C and 222°C, and still more preferably between about 219°C and 221°C, for example at a temperature of about 220°C.

89. The medical gas conduit according to any one of claims 1 to 88, wherein The medical gas conduit is configured to have a compliance of less than about 4 ml / cmH2O, preferably less than about 2.5 ml / cmH2O, and more preferably less than about 1.2 ml / cmH2O in at least one conditional state.

90. The medical gas conduit according to any one of claims 1 to 89, wherein When separated from the sheath, the elongated tube is configured to have a compliance in at least one conditional state of greater than about 4 ml / cmH2O, preferably greater than 5 ml / cmH2O.

91. The medical gas conduit according to any one of claims 1 to 90, wherein: The medical gas conduit is configured to have a flow resistance of: Less than about 0.06 cmH2O / l / min at a flow rate of 30 l / min; Less than about 0.12 cmH2O / l / min at a flow rate of 15 l / min; or Less than about 0.74 cmH2O / l / min at a flow rate of 2.5 l / min.

92. The medical gas conduit according to any one of claims 1 to 91, wherein The medical gas conduit is configured to increase resistance to flow by less than 150% with bending under at least one conditional state.

93. A medical gas conduit according to any one of claims 1 to 92, wherein the medical gas conduit is configured to comply with any one or more, and preferably all, of the length, leakage, flow resistance and compliance requirements of International Standard 5367:2014(E) of the International Organization for Standardization (ISO) in at least one conditional state.

94. The medical gas conduit according to any one of claims 1 to 93, wherein: The medical gas catheter is configured to have a compliance of less than about 4 ml / cmH2O, preferably less than about 2.5 ml / cmH2O, and more preferably less than about 1.2 ml / cmH2O after prolonged use.

95. The medical gas conduit according to any one of claims 1 to 94, wherein: When separated from the sheath, the elongated tube is configured to have a compliance exceeding about 4 ml / cmH2O, preferably exceeding 5 ml / cmH2O after prolonged use.

96. The medical gas conduit according to any one of claims 1 to 95, wherein: The medical gas conduit is configured to have the following flow resistance after prolonged use: Less than about 0.06 cmH2O / l / min at a flow rate of 30 l / min; Less than about 0.12 cmH2O / l / min at a flow rate of 15 l / min; or Less than about 0.74 cmH2O / l / min at a flow rate of 2.5 l / min.

97. The medical gas conduit according to any one of claims 1 to 96, wherein: The medical gas conduit is configured to increase resistance to flow by less than 150% with bending after prolonged use.

98. A medical gas conduit according to any one of claims 1 to 97, wherein the medical gas conduit is configured to comply with any one or more, and preferably all, of the length, leakage, flow resistance and compliance requirements of International Standard 5367:2014 (E) of the International Organization for Standardization (ISO) after long-term use.

99. The medical gas conduit according to any one of claims 1 to 98, wherein: The elongate tube and the sheath are flexible to reduce tube drag on one or more of a Y-piece and a patient interface of the medical gas system in use.

100. The medical gas conduit according to any one of claims 1 to 99, wherein: When separated from the sheath, the elongated tube is more flexible in a conditioned state than in an equilibrium state.

101. The medical gas conduit of any one of claims 1 to 100, the medical gas conduit comprising an expiratory conduit, the medical gas system comprising a respiratory assistance system, and the medical gas flow comprising a respiratory gas flow, wherein: The expiratory conduit is configured to form more than about 80%, preferably more than about 90%, and more preferably more than about 95% of the total length of the expiratory limb of the respiratory assistance system in use.

102. The medical gas conduit according to any one of claims 1 to 101, wherein: In a balanced state, the medical gas conduit or the elongated tube has the following length: between about 0.8 m and 1.2 m, for example about 1.0 m; Between about 1.0m and 2.5m, and preferably: between about 1.1 m and 1.4 m, and more preferably between about 1.2 m and 1.3 m, for example about 1.25 m; between about 1.4m and 1.6m, for example about 1.5m; between about 1.5m and 1.7m, for example about 1.6m; or between about 1.5m and 1.8m, for example about 1.6m or about 1.8m; or Between about 2.2m and 2.6m, more preferably between about 2.3m and 2.5m, for example about 2.4m.

103. The medical gas conduit according to any one of claims 1 to 102, in a balanced state, has a length measured between about 1.1 m and 1.8 m, preferably between about 1.2 m and 1.8 m, more preferably between about 1.2 m and 1.3 m, or between about 1.4 m and 1.6 m, or between about 1.5 m and 1.7 m, for example about 1.2 m or 1.5 m or 1.6 m.

104. The medical gas conduit according to any one of claims 1 to 103, wherein: In the dry state, the wall thickness of the elongated tube is between about 0.5 mm and 0.9 mm, preferably between about 0.6 mm and 0.8 mm, more preferably between about 0.65 mm and 0.75 mm, still more preferably between about 0.68 mm and 0.72 mm, and most preferably between about 0.69 mm and 0.71 mm, for example about 0.70 mm.

105. The medical gas conduit according to any one of claims 1 to 104, wherein: When separated from the sheath and in a saturated state, the wall thickness of the elongated tube is between about 0.7 mm and 1.1 mm, preferably between about 0.8 mm and 1.0 mm, more preferably between about 0.85 mm and 0.95 mm, still more preferably between about 0.90 mm and 0.94 mm, and most preferably between about 0.91 mm and 0.93 mm, for example about 0.92 mm.

106. The medical gas conduit according to any one of claims 1 to 105, wherein: In the dry state, the maximum outer diameter of the elongated tube is between about 20 mm and 26 mm, preferably between about 21 mm and 25 mm, and more preferably between about 22 mm and 24 mm, such as about 23 mm.

107. The medical gas conduit according to any one of claims 1 to 106, wherein: When in a saturated state separated from the sheath, the maximum outer diameter of the elongated tube is between about 25 mm and 35 mm, preferably between about 28 mm and 32 mm, and more preferably between about 29 mm and 31 mm, such as about 30 mm.

108. The medical gas conduit according to any one of claims 1 to 107, wherein: The elongated tube is extruded.

109. The medical gas conduit according to any one of claims 1 to 108, wherein: The elongated tube is corrugated.

110. The medical gas conduit according to any one of claims 1 to 109, wherein: The elongated tube is corrugated and the sheath is configured to be at least partially spaced apart from peaks of the corrugations of the elongated tube when the medical gas conduit is in an equilibrium state.

111. The medical gas conduit according to any one of claims 1 to 110, wherein: The medical gas conduit does not include reinforcing ridges or rods within the lumen.

112. The medical gas conduit according to any one of claims 1 to 111, wherein: The gas permeable material is configured, in use, to at least partially dry the flow of medicinal gas as it passes along the length of the lumen.

113. The medical gas conduit according to any one of claims 1 to 112, wherein: The at least one conditional state comprises a simulated conditional state.

114. The medical gas conduit of any one of claims 1 to 113, the medical gas system comprising a Y-piece and a gas source, the medical gas conduit being configured to be directly coupled to each of: an outlet of the Y-shaped member; and A gas return inlet of the gas source or a filter directly coupled to the gas return inlet.

115. The medical gas conduit according to any one of claims 1 to 114, wherein: The medical gas conduit does not include a water trap or is not provided with a water trap.

116. The medical gas conduit of any one of claims 1 to 115, configured for use as or in an expiratory limb of the medical gas system, wherein: The expiratory limb does not include a water trap.

117. The medical gas conduit according to any one of claims 1 to 116, wherein: The medical gas conduit does not include a heating wire.

118. A breathing circuit kit for use in a breathing assistance system, the breathing circuit kit comprising: Suction catheter; Y-shaped piece; as well as An expiratory conduit, at least one of the inspiratory conduit and the expiratory conduit comprising a medical gas conduit according to any one of claims 1 to 117.

119. The breathing circuit kit of claim 118, comprising a humidification chamber.

120. A breathing circuit kit according to claim 118 or 119, comprising any one or more of the following: Humidifier supply duct; patient interface; Filters; Pressure relief valve; pressure regulator; and Conduit mounting.

121. A breathing circuit kit according to any one of claims 118 to 120, which does not include at least one and preferably both of the following: a heating wire associated with the medical gas conduit; and A water trap is associated with the medical gas conduit.

122. An insufflation circuit kit comprising: A discharge conduit comprising a medical gas conduit according to any one of claims 1 to 117; as well as Emission filter.

123. The insufflation circuit kit of claim 122, comprising any one or more of the following: insufflator supply catheter; adapter; Humidifier supply duct; Blow into gas filter; Humidification chamber; funnel; delivery catheter; Surgical intubation; Diffuser; and Additional discharge conduit.

124. A respiratory assistance system for providing respiratory therapy to a patient, the respiratory assistance system comprising: a gas source configured to supply a flow of breathing gas; a humidifier configured to heat and humidify the flow of breathing gas; a humidifier supply conduit configured to deliver the flow of breathing gas from an outlet of the gas source to an inlet of the humidifier; an inspiratory conduit configured to convey the flow of breathing gas from the outlet of the humidifier to the inlet of the Y-piece or patient interface for supply to the patient; as well as an expiratory conduit configured to deliver the flow of medical gas from the outlet of the Y-piece or the patient interface to a gas return inlet of the gas source or a filter at the gas return inlet; At least one of the inspiratory conduit and the expiratory conduit comprises a medical gas conduit according to any one of claims 1 to 117.

125. A breathing assistance system according to claim 124, said breathing assistance system not comprising at least one and preferably both of the following: a heating wire associated with the medical gas conduit; and A water trap is associated with the medical gas conduit.

126. A surgical insufflation system configured to supply insufflation gas to a body cavity of a patient, the surgical insufflation system comprising: an insufflator configured to supply an insufflation gas flow; a humidifier configured to heat and humidify the insufflation gas stream; a humidifier supply conduit configured to convey the insufflation gas flow from the outlet of the insufflator to the inlet of the humidifier; a delivery conduit configured to convey the insufflation gas flow from the outlet of the humidifier to the inlet of the surgical cannula for supply to a body cavity of a patient; as well as An exhaust conduit configured to convey the insufflation gas flow and surgical smoke away from a body cavity of a patient, the exhaust conduit comprising a medical gas conduit according to any one of claims 1 to 117.

127. A method of forming a conduit for delivering a medical gas, the method comprising: disposing a sheath around an elongated tube defining a lumen for flowing a medical gas therethrough; clamping the first end of the sheath to the first end of the elongated tube; as well as A connector is overmolded to the first end of the sheath and the first end of the elongated tube to secure the connector, the sheath, and the elongated tube together.

128. The method of claim 127, the step of overmolding the connector comprising: inserting a first connector component at least partially into the lumen of the elongated tube wall at a first end of the elongated tube; as well as A second connector component is overmolded around the first connector component, the first end of the sheath, and the first end of the elongated tube.

129. The method according to claim 128, comprising the steps of: The first connector component is injection molded prior to at least partially inserting the first connector component into the first end of the elongate tube.

130. The method of any one of claims 127 to 129, the step of clamping the first end of the sheath to the first end of the elongated tube comprising: The first end of the sheath and the first end of the elongated tube are positioned within a mold tool that includes a plurality of protrusions that engage and clamp the sheath to the elongated tube.

131. The method of claim 130, wherein the plurality of protrusions form a plurality of apertures in the connector when the connector is overmolded, wherein: The sheath is exposed through the plurality of apertures.

132. The method according to any one of claims 127 to 131, comprising the steps of: clamping the second end of the sheath to the second end of the elongated tube; as well as A second connector is overmolded onto the second end of the sheath and the second end of the elongated tube to secure the second connector, the second end of the sheath, and the second end of the elongated tube together.

133. The method according to claim 132, comprising the steps of: Before clamping the second end of the sheath to the second end of the elongated tube, the sheath is contracted in the longitudinal direction so that the second end of the sheath covers the second end of the elongated tube.

134. A method according to any one of claims 127 to 133, comprising the step of extruding the elongated tube.

135. The method of claim 134, comprising the step of corrugating the elongated tube.

136. The method of claim 134 or 135, comprising the step of cutting the elongated tube from a tubular extrusion.

137. A method according to any one of claims 127 to 136, comprising the step of cutting the sheath from a length of sheath material into predetermined sheath lengths, wherein: The predetermined sheath length is selected such that when the sheath is disposed about the elongated tube and the sheath is deformed to the length of the elongated tube, the sheath is at least partially spaced apart from the elongated tube in a radial direction.

138. A method according to any one of claims 127 to 137, wherein the sheath comprises a tubular mesh, preferably a braided tubular mesh.

139. The method of any one of claims 127 to 138, wherein the sheath comprises at least one of: Between about 75 and 125 monofilament or multifilament knitting elements, preferably between about 90 and 100 knitting elements, such as about 96 knitting elements; and Between about 150 and 250 filaments, and preferably between about 180 and 200 filaments, for example about 192 filaments.

140. The method of any one of claims 127 to 138, wherein the sheath comprises at least one of: Between about 40 and 60 monofilament or multifilament knitting elements, preferably between about 45 and 55 knitting elements, such as about 48 knitting elements; and Between about 120 and 180 filaments, and preferably between about 135 and 165 filaments, such as about 144 filaments.

141. The method of any one of claims 127 to 140, wherein the elongated tube comprises a gas permeable material, preferably a block copolymer, and more preferably a block copolymer comprising: a hard segment of polybutylene terephthalate; and The soft segment of ether-type macroethylene glycol.

142. The method of any one of claims 127 to 141 excluding the step of providing the conduit with at least one, and preferably both, of a heating wire and a water trap.

143. A catheter formed by the method of any one of claims 127 to 142, wherein: The elongated tube is configured to expand upon absorbing water molecules, and the sheath is configured to selectively constrain expansion of the elongated tube in use.

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