Medical tubing for breathing circuits

Abstract

The present invention provides medical tubing for use in breathing circuits suitable for supplying humidifying gas to a patient and / or removing gas from a patient, such as in respiratory humidification systems. [Solution] A breathing circuit 100 for use in respiratory therapy includes an inspiratory tube 103 and an expiratory tube 117. The inspiratory tube 103 of the breathing circuit 100 has a smooth bore. The expiratory tube 117 of the breathing circuit 100 is corrugated. Preferably, the expiratory tube 117 is vapor permeable. Using a combination of a smooth bore inspiratory tube 103 and a corrugated expiratory tube 117 improves the performance of the breathing circuit 100 and its components.

Description

Technical Field

[0001] Incorporation by Reference This application claims priority from U.S. Provisional Patent Application No. 62 / 621,463, filed Jan. 24, 2018, the entire content of which is incorporated herein by reference in its entirety. This application is related to International Application PCT / New Zealand Patent Application Publication No. 2017 / 050,099, filed Jul. 21, 2017, and U.S. Provisional Patent Application No. 62 / 365,285, filed Jul. 21, 2016, the entire content of each of which is incorporated herein by reference in its entirety. Further, the following disclosure references various features of U.S. Patent Application Publication No. 13 / 517,925, published as U.S. Patent Application Publication No. 2013 / 0098360A1, U.S. Patent Application Publication No. 14 / 123,485, published as U.S. Patent Application Publication No. 2014 / 0202462A1, and U.S. Patent Application Publication No. 14 / 649,801, published as U.S. Patent Application Publication No. 2015 / 0306333A1. The entire disclosures of these applications and publications are hereby incorporated by reference in their entirety as if fully set forth herein for all purposes.

[0002] The present disclosure generally relates to tubes suitable for medical use, particularly medical tubes for use in a breathing circuit suitable for providing humidified gas to a patient and / or removing gas from a patient, such as in a respiratory humidification system.

Background Art

[0003] In a breathing circuit, various components carry heated and / or humidified gas to and from a patient. Respiratory humidification helps reduce the likelihood of infection and / or tissue damage.

Summary of the Invention

[0004] Certain features, embodiments, and advantages of this disclosure recognize the need for improvements that can increase the removal of vapor from the exhaled gas in the expiratory tube while increasing the amount of vapor in the humidified gas delivered to the patient through the inspiratory tube without increasing the overall flow resistance in the tube. Certain features, embodiments, and advantages of this disclosure recognize the need for improvements that reduce the compressive capacity of the breathing circuit, or at least reduce the compressive capacity of the rim of the breathing circuit. As described herein, trade-offs may exist between the inspiratory and expiratory tubes in both compressive capacity and flow resistance. A decrease in compressive capacity and / or flow resistance in the inspiratory tube and an increase in compressive capacity and / or flow resistance in the expiratory tube may exist. A decrease in compressive capacity in the inspiratory tube may be at least in part due to a decrease in the diameter of the inspiratory tube. A decrease in diameter may be made possible by a decrease in flow resistance, which may be at least in part due to having a smooth bore. An increase in compressive capacity in the expiratory tube may be at least in part due to an increase in the surface area of ​​the wall, the diameter of the tube, the cross-sectional area of ​​the tube, or the length of the wall of the expiratory tube. An increase in flow resistance in the expiratory tube may be at least in part due to a corrugated structure. An increase in compressive volume and flow resistance within the expiratory tube can improve its permeability due to various factors as described herein. This trade-off between the inspiratory and expiratory tubes allows for the maintenance of the same overall compressive volume and / or flow resistance within the breathing circuit as a whole.

[0005] The lower the compression capacity of the breathing circuit, the lower the air compliance of the breathing circuit for a given degree of stretching. The lower the air compliance of the breathing circuit is relative to the patient's lung compliance, the less likely there is to be an error in the tidal volume delivered.

[0006] A circuit kit for use in patient respiratory therapy may include a breathing circuit. The breathing circuit may include an inspiratory tube configured to receive an inspiratory gas flow from a gas source. The inspiratory tube may include an inspiratory inlet, an inspiratory outlet, and an inner wall surrounding an inspiratory central bore. The inner wall of the inspiratory tube may be smooth. The breathing circuit may also include an expiratory tube configured to receive an expiratory gas flow from the patient. The expiratory tube may include an expiratory inlet, an expiratory outlet, and an inner wall surrounding an expiratory central bore. The inner wall of the exhalation tube may be wavy. The inspiratory tube may have an inner diameter of 5 to 14.5 mm. The exhalation tube may have a nominal inner diameter of 15 to 22 mm. The inspiratory tube may have an inner diameter of 4 to 17 mm. The exhalation tube may have a nominal inner diameter of 10.5 to 20.5 mm.

[0007] The circuit kit may include a Y-piece configured to connect the inhalation tube and the exhalation tube. The circuit kit may also include a chamber for holding a certain amount of water and for placement on the humidifier. The circuit kit may include a dryline for transporting flow from a ventilator or other gas source to the humidifier inlet. The intake pipe may have an inner diameter of 6mm to 14mm. The intake pipe may have an inner diameter of 6mm to 13mm. The intake pipe may have an inner diameter of 6mm to 12mm. The intake pipe may have an inner diameter of 6mm to 11mm. The intake pipe may have an inner diameter of 7mm to 10mm. The inspiratory tube may have an inner diameter of 8mm to 9mm. The expiratory tube may have a nominal inner diameter of 15.5mm to 21mm. The expiratory tube may have a nominal inner diameter of 16mm to 20mm. The expiratory tube may have a nominal inner diameter of 16mm to 19mm. The expiratory tube may have a nominal inner diameter of 18mm to 20mm. The expiratory tube may have a nominal inner diameter of 19mm to 20mm. The inspiratory tube may have an inner diameter of 6mm to 10mm. The inspiratory tube may have an inner diameter of 11mm to 15mm. The inspiratory tube may have an inner diameter of 9mm to 13mm. The inspiratory tube may have an inner diameter of 10mm to 14mm. The inspiratory tube may have an inner diameter of 7mm to 13mm. The inspiratory tube may have an inner diameter of 8mm to 14mm. The exhalation tube may have a nominal inner diameter of 11 mm to 15 mm. The exhalation tube may have a nominal inner diameter of 12 mm to 16 mm. The exhalation tube may have a nominal inner diameter of 14 mm to 18 mm. The exhalation tube may have a nominal inner diameter of 16 mm to 20 mm. The exhalation tube may have a nominal inner diameter of 13 mm to 19 mm. The exhalation tube may have a nominal inner diameter of 14 mm to 20 mm. The inspiratory or exhalation tube may have a length of 1.5 m to 2.5 m. The inspiratory or expiratory tube may have a length of 1.6 m to 2.5 m. The inspiratory tube may surround a heating element within the inspiratory center bore or within the tube wall. The expiratory tube may contain a heating element. The expiratory tube may be permeable. The inner wall of the expiratory tube may be permeable to water vapor and substantially impermeable to the bulk flow of liquid and exhaled gas flowing through the expiratory tube. The inspiratory tube may contain a plurality of bubbles in longitudinal cross-section, each having a flat surface that forms at least a portion of the wall of the inspiratory center bore. The circuit kit may be suitable for treating patients with a tidal volume in the range of 50 ml to 300 ml. The circuit kit may be suitable for treating pediatric and adolescent patients. The difference between the inner diameter of the inspiratory tube and the nominal diameter of the expiratory tube may be 1 mm to 14 mm. The inner diameter of the inspiratory tube may be 1 mm to 14 mm smaller than the nominal diameter of the expiratory tube. The inhalation tube and / or exhalation tube may include multiple sections for housing other equipment such as a water trap and / or an intermediate connector with one or more sensors and / or a PCB and / or a controller. The system may include a circuit kit and a humidifier.

[0008] A circuit kit for use in patient respiratory therapy may include a breathing circuit. The breathing circuit may include an inspiratory tube configured to receive an inspiratory gas flow from a gas source. The inspiratory tube may include an inspiratory inlet, an inspiratory outlet, and an inner wall surrounding an inspiratory central bore. The inner wall of the inspiratory tube may be smooth. The breathing circuit may also include an expiratory tube configured to receive an expiratory gas flow from the patient. The expiratory tube may include an expiratory inlet, an expiratory outlet, and an inner wall surrounding an expiratory central bore. The inner wall of the exhalation tube may be wavy. The inspiratory tube may have an inner diameter of 10-21 mm. The exhalation tube may have a nominal inner diameter of 22-30 mm. The inspiratory tube may have an inner diameter of 9.5-24 mm. The exhalation tube may have a nominal inner diameter of 19-31.5 mm.

[0009] The circuit kit may include a Y-piece configured to connect the inhalation tube and the exhalation tube. The circuit kit may also include a chamber for holding a certain amount of water and for placement on the humidifier. The circuit kit may include a dryline for transporting flow from the ventilator or other gas source to the humidifier outlet. The inhalation tube may have an inner diameter of 10mm to 20mm. The inhalation tube may have an inner diameter of 11mm to 20mm. The inhalation tube may have an inner diameter of 11mm to 19mm. The inhalation tube may have an inner diameter of 11mm to 18mm. The inhalation tube may have an inner diameter of 11mm to 17mm. The inhalation tube may have an inner diameter of 11mm to 16mm. The inhalation tube may have an inner diameter of 11mm to 15mm. The inhalation tube may have an inner diameter of 12mm to 15mm. The inhalation tube may have an inner diameter of 13mm to 14mm. The exhalation tube may have a nominal inner diameter of 22mm to 29mm. The exhalation tube may have a nominal inner diameter of 23mm to 30mm. The exhalation tube may have a nominal inner diameter of 24mm to 30mm. The exhalation tube may have a nominal inner diameter of 24mm to 29mm. The exhalation tube may have a nominal inner diameter of 25mm to 28mm. The exhalation tube may have a nominal inner diameter of 25.5mm to 27mm. The inspiratory tube may have an inner diameter of 11mm to 15mm. The inspiratory tube may have an inner diameter of 12mm to 16mm. The inspiratory tube may have an inner diameter of 18mm to 22mm. The inspiratory tube may have an inner diameter of 19mm to 23mm. The inspiratory tube may have an inner diameter of 10mm to 16mm. The inspiratory tube may have an inner diameter of 17mm to 23mm. The exhalation tube may have a nominal inner diameter of 25mm to 29mm. The exhalation tube may have a nominal inner diameter of 26mm to 30mm. The exhalation tube may have a nominal inner diameter of 20 mm to 24 mm. The exhalation tube may have a nominal inner diameter of 21 mm to 25 mm. The exhalation tube may have a nominal inner diameter of 24 mm to 30 mm. The exhalation tube may have a nominal inner diameter of 20 mm to 26 mm. The inspiratory or exhalation tube may have a length of 1.5 m to 2.5 m. The inspiratory or exhalation tube may have a length of 1.6 m to 2.5 m. The inspiratory tube may surround a heating element within the inspiratory center bore or within the tube wall. The exhalation tube may contain a heating element. The exhalation tube may be permeable. The inner wall of the exhalation tube may be permeable to water vapor and substantially impermeable to the bulk flow of liquid and exhaled gas flowing through the exhalation tube. The inspiratory tube may include a plurality of bubbles, each having a flat surface that forms at least a portion of the wall of the inspiratory center bore in a longitudinal cross-section. The circuit kit may be suitable for treating patients with a tidal volume greater than 300 ml. The circuit kit may be suitable for treating adult patients.The difference between the inner diameter of the inspiratory tube and the nominal diameter of the expiratory tube may be 1 mm to 20 mm. The inner diameter of the inspiratory tube may be 1 mm to 20 mm smaller than the nominal diameter of the expiratory tube. The inspiratory and / or expiratory tubes may include multiple sections for housing other equipment such as a water trap and / or an intermediate connector with one or more sensors and / or a PCB and / or a controller. The system may include a circuit kit and a humidifier.

[0010] A circuit kit for use in patient respiratory therapy may include a breathing circuit. The breathing circuit may include an inspiratory tube configured to receive an inspiratory gas flow from a gas source. The inspiratory tube may include an inspiratory inlet, an inspiratory outlet, and an inner wall surrounding an inspiratory central bore. The inner wall of the inspiratory tube may be smooth. The breathing circuit may also include an expiratory tube configured to receive an expiratory gas flow from the patient. The expiratory tube may include an expiratory inlet, an expiratory outlet, and an inner wall surrounding an expiratory central bore. The inner wall of the exhalation tube may be wavy. The inspiratory tube may have an inner diameter of 4-12 mm. The exhalation tube may have a nominal inner diameter of 13-18 mm. The inspiratory tube may have an inner diameter of 3-13 mm. The exhalation tube may have a nominal inner diameter of 9.5-19 mm.

[0011] The circuit kit may include a Y-piece configured to connect the inhalation tube and the exhalation tube. The circuit kit may also include a chamber for holding a certain amount of water and for placement on the humidifier. The circuit kit may include a dryline for transporting the flow from the ventilator to another gas source and to the humidifier inlet. The inhalation tube may have an inner diameter of 5mm to 11mm. The inhalation tube may have an inner diameter of 6mm to 10mm. The inhalation tube may have an inner diameter of 6mm to 8mm. The inhalation tube may have an inner diameter of 9mm to 10mm. The exhalation tube may have a nominal inner diameter of 13mm to 17mm. The exhalation tube may have a nominal inner diameter of 14mm to 17mm. The exhalation tube may have a nominal inner diameter of 15mm to 16.5mm. The exhalation tube may have a nominal inner diameter of 14mm to 15mm. The inhalation tube or exhalation tube may have a length of 1.5m to 2.5m. The inhalation tube or exhalation tube may have a length of 1.6m to 2.5m. The intake tube may have an inner diameter of 5 mm to 9 mm. The intake tube may have an inner diameter of 6 mm to 10 mm. The intake tube may have an inner diameter of 7 mm to 11 mm. The inspiratory tube may have an inner diameter of 8mm to 12mm. The inspiratory tube may have an inner diameter of 4mm to 11mm. The inspiratory tube may have an inner diameter of 6mm to 12mm. The exhaling tube may have a nominal inner diameter of 13mm to 17mm. The exhaling tube may have a nominal inner diameter of 12mm to 16mm. The exhaling tube may have a nominal inner diameter of 11mm to 15mm. The exhaling tube may have a nominal inner diameter of 14mm to 18mm. The exhaling tube may have a nominal inner diameter of 12mm to 18mm. The exhaling tube may have a nominal inner diameter of 10mm to 16mm. The inspiratory tube may surround a heating element within the inspiratory center bore or within the tube wall. The exhaling tube may contain a heating element. The exhaling tube may be permeable. The inner wall of the exhalation tube may be permeable to water vapor and substantially impermeable to the bulk flow of liquid and exhaled gas flowing through the exhalation tube. The inspiratory tube may include a plurality of bubbles, each having a flat surface that forms at least a portion of the wall of the inspiratory center bore in longitudinal cross-section. The circuit kit may be suitable for treating patients with a tidal volume of 50 ml or less. The circuit kit may be suitable for treating neonatal patients. The difference between the inner diameter of the inspiratory tube and the nominal diameter of the exhalation tube may be 1 mm to 14 mm. The inner diameter of the inspiratory tube may be 1 mm to 14 mm smaller than the nominal diameter of the exhalation tube. The inspiratory tube and / or exhalation tube may include a plurality of sections for housing other equipment such as a water trap and / or an intermediate connector with one or more sensors and / or a PCB and / or a controller. The system may include a circuit kit and a humidifier.

[0012] A circuit kit may be provided for use in respiratory therapy for a patient. The breathing circuit may include an inspiratory tube configured to receive an inspiratory gas flow from a gas source. The inspiratory tube may include an inspiratory inlet, an inspiratory outlet, and an inner wall surrounding an inspiratory central bore. The inner wall of the inspiratory tube may be smooth. The breathing circuit may include an expiratory tube configured to receive an expiratory gas flow from the patient. The expiratory tube may include an expiratory inlet, an expiratory outlet, and an inner wall surrounding an expiratory central bore. The inner wall of the expiratory tube may be corrugated.

[0013] In some embodiments, the inspiratory tube may have an inner diameter of 3 mm to 11 mm, and the expiratory tube may have a nominal inner diameter of 8 mm to 16 mm. The inspiratory tube may have an inner diameter of 4 mm to 8 mm. The expiratory tube may have a nominal inner diameter of 11 mm to 15 mm. The inspiratory tube may have an inner diameter of 6 mm to 10 mm. The expiratory tube may have a nominal inner diameter of 10 mm to 14 mm. The inspiratory tube or expiratory tube may have a length of 1.5 m to 2.5 m. In some embodiments, the inspiratory tube may have an inner diameter of 5 mm to 13 mm, and the expiratory tube may have a nominal inner diameter of 15 mm to 23 mm. The inspiratory tube may have an inner diameter of 5 mm to 9 mm. The expiratory tube may have a nominal inner diameter of 18 mm to 22 mm. The inspiratory tube may have an inner diameter of 8 mm to 12 mm. The exhalation tube may have a nominal inner diameter of 16 mm to 20 mm. The inspiratory or exhalation tube may have a length of 1.5 m to 2.5 m. In some embodiments, the inspiratory tube may have an inner diameter of 10 mm to 18 mm, and the exhalation tube may have a nominal inner diameter of 24 mm to 32 mm. The inspiratory tube may have an inner diameter of 9 mm to 13 mm. The exhalation tube may have a nominal inner diameter of 27 mm to 31 mm. The inspiratory tube may have an inner diameter of 15 mm to 19 mm. The exhalation tube may have a nominal inner diameter of 24 mm to 28 mm. The inspiratory or exhalation tube may have a length of 1.5 m to 2.5 m. The inspiratory tube may have an inner diameter and length. The exhalation tube may have a nominal inner diameter and length. In some embodiments, the circuit kit is suitable for the treatment of adult patients. In some embodiments, the circuit kit is suitable for the treatment of pediatric and adolescent patients. In some embodiments, the circuit kit is suitable for treating pediatric and neonatal patients.

[0014] The breathing circuit may include an inspiratory rim for transporting inhaled gas to the patient. The inspiratory rim may include a first elongated member containing a hollow body, which is spirally wound to form at least partially a first elongated tube having a longitudinal axis, a first lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen. The inspiratory rim may include a second elongated member spirally wound and joined between adjacent windings of the first elongated member, the second elongated member forming at least a portion of the lumen of the first elongated tube. The breathing circuit may include an expiratory rim for transporting exhaled gas from the patient. The expiratory rim may include an inlet and an outlet. The expiratory rim may include a third elongated member containing a second tube surrounding the second lumen. The second lumen can be configured to accommodate a bulk flow of exhaled gas, and the second tube is permeable to water vapor and substantially impermeable to liquid water and a bulk flow of exhaled gas.

[0015] The walls of the exhalation tube may contain foamed or non-foamed polymers that are permeable to water vapor and substantially impermeable to liquid water and bulk flow of exhaled gas. Foamed polymers may include solid thermoplastic elastomer materials having pores distributed throughout. Non-foamed polymers may include extruded solid thermoplastic elastomer materials that are permeable to water vapor and substantially impermeable to liquid water and bulk flow of exhaled gas. The first lumen of the inspiratory rim may have a smooth bore. The second elongated member of the inspiratory rim may surround at least one heating element. The first elongated member of the inspiratory rim may form a plurality of bubbles in its longitudinal cross-section, having flat surfaces in the lumen. The second elongated member of the inspiratory rim may surround at least one heating element, and at least one inspiratory heating element is located between one of the bubbles and the inspiratory center bore. The third elongated member of the exhalation rim may be corrugated. The first elongated tube may surround a heating element within its lumen. A third elongated member of the exhalation rim may surround a heating element within the second lumen. The third elongated member of the exhalation rim may include a heating element attached to the inner wall of the second tube. The third elongated member of the exhalation rim may include a heating element embedded in the wall of the second tube. The second tube may have an inner surface adjacent to the second lumen, and the exhalation rim may further include a plurality of reinforcing ribs arranged circumferentially on the inner surface and generally longitudinally aligned between the inlet and outlet.

[0016] The device may include a breathing circuit. The breathing circuit may include an inspiratory tube configured to receive an inspiratory gas flow from a gas source, the inspiratory tube including an inspiratory inlet, an inspiratory outlet, and a wall surrounding an inspiratory central bore. The inner wall of the inspiratory tube may be smooth. The breathing circuit may include an expiratory tube configured to receive an expiratory gas flow from the patient. The expiratory tube may include an expiratory inlet, an expiratory outlet, and a wall surrounding an expiratory central bore. The inner wall of the expiratory tube may be corrugated. The wall of the expiratory tube may be permeable to water vapor and substantially impermeable to the bulk flow of liquid and expiratory gas flowing through the expiratory tube.

[0017] The walls of the exhalation tube may contain a foamed or non-foamed polymer that is permeable to water vapor and substantially impermeable to liquid water and bulk flow of exhaled gas. The inspiratory tube may surround a heating element within its central bore. The inspiratory tube may contain a heating element attached to its wall. The inspiratory tube may contain a heating element embedded in its wall. The exhalation tube may contain a heating element within its central bore. The exhalation tube may contain a heating element attached to its inner wall. The exhalation tube may contain heating embedded in its inner wall. The inspiratory tube may contain a plurality of bubbles having a lumen-flat surface in its longitudinal cross-section. The inspiratory tube may contain at least one heating element, the at least one inspiratory heating element located between one of the plurality of bubbles and the inspiratory central bore. The exhalation tube may contain a plurality of reinforcing ribs arranged circumferentially on its inner surface and generally longitudinally aligned between the inlet and outlet. The breathing circuit may include a humidifier configured to humidify the inspiratory gas flow to the patient. The humidifier may include a humidifying chamber configured to store a certain amount of liquid and to be in fluid communication with the inspiratory gas flow. The humidifier may include a heater configured to heat a certain amount of liquid in the humidifying chamber to generate vapor so that the inspiratory gas flow is humidified with vapor.

[0018] The respiratory apparatus may include a humidifier configured to humidify the inspiratory gas flow to the patient. The respiratory apparatus may include an inspiratory tube configured to receive the inspiratory gas flow from the humidifier. The inspiratory tube may include an inspiratory inlet, an inspiratory outlet, and a wall surrounding an inspiratory center bore. The inner wall of the inspiratory tube may be smooth. The respiratory apparatus may include an expiratory tube configured to receive an expiratory gas flow from the patient. The expiratory tube may include an expiratory inlet, an expiratory outlet, and a wall surrounding an expiratory center bore. The expiratory center bore may be corrugated. The wall of the expiratory tube may be permeable to water vapor and substantially impermeable to the bulk flow of liquid and expiratory gas flowing through the expiratory tube.

[0019] The inhalation tube may include at least one heating element within its central bore. The inhalation tube may include at least one heating element attached to its inner wall. The inhalation tube may include at least one heating element surrounded within its wall. The exhalation tube may include at least one heating element within its exhalation central bore. The exhalation tube may include at least one heating element attached to its inner wall. The exhalation tube may include at least one heating element embedded within its inner wall. In a longitudinal cross-section, the inhalation tube may include a helically wound member that forms a plurality of bubbles having a flat surface in the inhalation central bore. The inhalation tube can surround at least one heating element, and at least one inhalation heating element may be between a bubble among the plurality of bubbles and the inhalation central bore. The wall of the exhalation tube may include a foamed polymer.

[0020] The respiratory apparatus may include a humidifier configured to humidify the inspiratory gas flow to the patient. The humidifier may include a humidification chamber configured to store a certain amount of liquid and to be in fluid communication with the inspiratory gas flow. The humidifier may include a heater configured to heat a certain amount of liquid in the humidification chamber to generate vapor so that the inspiratory gas flow is humidified with vapor. The respiratory apparatus may include an inspiratory tube configured to receive the humidified inspiratory gas flow from the humidifier. The inspiratory tube may include a wall surrounding an inspiratory central bore. The inspiratory central bore of the inspiratory tube may be smooth. The inspiratory tube may include a first elongated helical member that, in longitudinal cross-section, forms a plurality of bubbles having flat surfaces in the inspiratory central bore. The bubbles may be configured to insulate the inspiratory central bore. The inspiratory tube may include a second helically wound elongated member joined between adjacent windings of a first elongated member, the second elongated member forming at least a portion of the lumen of the first elongated tube and including at least one inspiratory heating element embedded within the second elongated member. The respiratory device may include an expiratory tube configured to receive an expiratory gas flow from the patient. The expiratory tube may include a conduit surrounding an expiratory center bore. The expiratory center bore may be corrugated. The conduit may be permeable to water vapor and substantially impermeable to a liquid flow through the conduit. The expiratory tube may include at least one expiratory heating element within the expiratory center bore. The respiratory device may include a humidifier heater, a control system configured to deliver power to at least one inspiratory heating element and at least one expiratory heating element.

[0021] The walls of the exhalation tube may comprise a foamed or non-foamed polymer that is permeable to water vapor and substantially impermeable to liquid water and bulk flow of exhaled gas. The foamed polymer may comprise a solid thermoplastic elastomer material having pores distributed throughout. The non-foamed polymer may comprise an extruded solid thermoplastic elastomer material that is permeable to water vapor and substantially impermeable to liquid water and bulk flow of exhaled gas. At least one inspiratory heating element may be located between a bubble of a plurality of bubbles and the inspiratory center bore. The breathing apparatus may comprise a patient interface assembly between the inspiratory tube and the exhalation tube. Power delivered by the control system may be calculated to provide increased humidification by a humidifier and controlled condensate management by at least one exhalation heating element and at least one inspiratory heating element. The breathing apparatus may comprise a ventilator configured to supply an inspiratory gas flow and receive an exhaled gas flow. The ventilator may be configured to supply a pulsed inspiratory gas flow to the humidifier. The ventilator may be configured to supply a constant intake gas flow to the humidifier. The ventilator may be configured to supply a biased flow of gas.

[0022] The respiratory apparatus may include a humidifier configured to humidify the inspiratory gas flow to the patient. The respiratory apparatus may include an inspiratory tube configured to receive the inspiratory gas flow from a gas source. The inspiratory tube may include an inspiratory inlet, an inspiratory outlet, and a wall surrounding the central inspiratory bore. The inner wall of the inspiratory tube may be smooth. The respiratory apparatus may include an expiratory tube configured to receive the expiratory gas flow from the patient. The expiratory tube may include an expiratory inlet, an expiratory outlet, and a wall surrounding the central expiratory bore. The inner wall of the expiratory tube may be corrugated. The wall of the expiratory tube may be permeable to water vapor and substantially impermeable to the bulk flow of liquid and expiratory gas flowing through the expiratory tube.

[0023] The walls of the exhalation tube may contain a foamed or non-foamed polymer that is permeable to water vapor and substantially impermeable to liquid water and bulk flow of exhaled gas. The inspiratory tube may contain at least one heating element within its central bore. The inspiratory tube may contain at least one heating element attached to its inner wall. The inspiratory tube may contain at least one heating element surrounded within its wall. The first elongated member of the inspiratory rim may form a plurality of bubbles in its longitudinal cross-section, having a flat surface in the lumen. The inspiratory tube may surround at least one heating element, and at least one inspiratory heating element may be between a bubble among the plurality of bubbles and the inspiratory central bore. The exhalation tube may contain at least one heating element within its exhalation central bore. The exhalation tube may contain at least one heating element attached to its inner wall. The exhalation tube may contain at least one heating element embedded within its inner wall. The exhalation tube may include a number of reinforcing ribs arranged circumferentially on its inner surface and generally aligned longitudinally between the inlet and outlet. The breathing apparatus may include a humidifier heater and a control system configured to deliver power to at least one heating element.

[0024] The breathing circuit may include a combination of a smooth-bore inspiratory tube and a corrugated vapor-permeable expiratory tube to increase the vapor in the humidified gas delivered to the patient through the inspiratory rim of the circuit, and to increase the removal of vapor from the expiratory gas in the expiratory rim of the circuit, without increasing the overall flow resistance of the tube, thus avoiding an increase in pressure loss within the breathing circuit. The smooth-bore inspiratory tube can offer an opportunity for trade-offs. A smooth bore can reduce flow resistance, thereby allowing for a reduction in the diameter or cross-sectional area of ​​the inspiratory tube while maintaining acceptable flow resistance. This reduction in the diameter or cross-sectional area of ​​the inspiratory tube reduces the compressive capacity of the inspiratory tube. A smaller diameter inspiratory tube can reduce the compressive capacity of at least a portion of the breathing circuit, thereby reducing the potential for error in the delivered tidal volume. A ventilator is typically designed to deliver a set amount of gas to the patient with each breath ("tidal volume"). Reducing errors in the delivered tidal volume can ensure that the patient receives the correct amount of gas.

[0025] The combination of a smooth-bore inspiratory tube and a corrugated expiratory tube has an unexpected synergistic effect that improves the performance of the breathing circuit and its components beyond expectations. Using a smooth-bore inspiratory tube with a smaller bore than an equivalent corrugated tube can reduce the tube's compression capacity. This reduction in compression capacity ensures that the appropriate amount of gas is delivered to the patient. As described herein, inspiratory tubes with smaller bore diameters can reduce the overall compression capacity and air compliance of the breathing circuit. As described herein, an inspiratory tube having a smaller inner diameter may have a reduced compression capacity, which may be a trade-off with an increased compression capacity of the expiratory tube.

[0026] For practical reasons, the compressive capacity, and therefore compliance, of a breathing circuit tube is usually much greater than that of the patient's lungs. Factors influencing the compressive capacity of a breathing circuit tube include minimizing the tube's resistance to gas flow and ensuring the tube is long enough to manage the patient within the bed space. This is exacerbated by certain lung conditions, which result in the patient having very rigid, low-compliance lungs. In addition, reduced length (e.g., shortened tube) leads to lower compressive capacity, which directly conflicts with both the maneuverability and breathability of the expiratory rim. In practice, longer tubes are generally better, for example, to allow for freedom of movement and positioning of the patient. In practice, at the expiratory rim, a larger surface area is generally better to increase the breathability of the expiratory rim.

[0027] To maintain a sufficiently low compression capacity, there are potential trade-offs between the components of the breathing circuit. The diameter or cross-sectional area of ​​the inspiratory tube can be reduced. However, reducing the inner diameter of the inspiratory tube also increases the flow resistance (RTF) within the inspiratory tube. Since a smooth bore reduces RTF compared to a tube with a corrugated bore or another type of non-smooth bore, it has been found that this increase in RTF can be compensated for by smoothing the inner bore of the inspiratory tube. The use of a smooth bore also has the additional benefit of reducing vapor and condensate trapping. It has also been found that if the reduction in RTF resulting from the use of a smooth bore outweighs the increase in RTF resulting from reducing the inner diameter of the tube, there is a net reduction in RTF in the breathing circuit or at least a net reduction in RTF in the inspiratory tube. A smooth bore of the inspiratory tube reduces RTF, thereby allowing for a reduction in the diameter of the inspiratory tube, which normally increases RTF, and the smoothness of the bore can balance the reduction in diameter. As described herein, a reduction in diameter or cross-sectional area can reduce compression capacity. This decrease in the compression capacity of the inspiratory tube can be offset by an increase in the compression capacity of the expiratory tube, such as by increasing the diameter or cross-sectional area of ​​the expiratory tube. Increasing the diameter or cross-sectional area of ​​the expiratory tube results in a larger surface area of ​​the expiratory tube, which increases the vapor permeability of the expiratory tube.

[0028] Specific features, embodiments, and advantages of an invention embodying the invention relating to the compressive capacity of components of a breathing circuit are as follows: characterized by one or more combinations of: a reduction in the inner diameter of the inspiratory tube, a smooth bore of the inspiratory tube, a reduction in the compressive capacity of the inspiratory tube, an increase in the compressive capacity of the expiratory tube, an increase in the diameter of the expiratory tube, an increase in the surface area of ​​the expiratory tube, and / or an increase in the vapor permeability of the expiratory tube. Specific features, embodiments, and advantages of the present disclosure reflect the embodiment of the invention in which this net reduction in RTF by a smooth bore inspiratory tube allows for modification of other components of the circuit without changing the overall compressive capacity, overall RTF, and / or overall pressure loss of the circuit as a whole. Using a smooth bore inspiratory tube allows for the use of longer, more wavy expiratory tubes, which would otherwise increase the RTF in the circuit. Increasing the length of the expiratory tube improves the tube's ability to remove vapor from the exhaled gas, at least partially by increasing the residence time. Increasing the diameter of the expiratory tube can improve the tube's ability to remove vapor from the exhaled gas, by increasing the surface area of ​​the vapor-permeable walls. When the use of a smooth-bore inspiratory tube reduces the overall RTF of the circuit, the increase in RTF resulting from an increase in the length of the expiratory tube may not result in a net increase in RTF, a net increase in compression capacity, and / or a corresponding pressure loss in the overall circuit. For example, depending on the design, an increase in the length of the expiratory tube and a decrease in the diameter of a smooth-bore inspiratory tube may be net neutral with respect to RTF.

[0029] Using a smooth-bore inspiratory tube in a breathing circuit instead of a corrugated or similarly non-smooth-walled tube can be combined with using a wider (larger cross-sectional area or diameter) expiratory tube in the breathing circuit, which reduces RTF. The trade-off in this case may not be in the reduction of RTF in both tubes. A smooth bore reduces RTF compared to a tube with a corrugated bore or another type of non-smooth bore. However, the reduction in RTF in the inspiratory tube may be offset by a reduction in diameter or cross-sectional area that increases RTF. An expiratory tube with a larger cross-sectional area or diameter also reduces RTF. Alternatively, there may be a trade-off in compressive volume due to changes in the diameter or cross-sectional area of ​​the inspiratory and expiratory tubes, which decreases in the inspiratory tube but increases in the expiratory tube. A smaller diameter inspiratory tube has a smaller compressive volume. A larger diameter expiratory tube has a larger compressive volume.

[0030] The breathing circuit may include an inspiratory rim for transporting inspiratory gas to the patient. The inspiratory rim includes a first elongated member containing a hollow body, which is spirally wound to form at least partially a first elongated tube having a longitudinal axis, a first lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen. The inspiratory rim further includes a second elongated member spirally wound and joined between adjacent windings of the first elongated member, the second elongated member forming at least a portion of the inner wall of the lumen of the first elongated tube. The breathing circuit further includes an expiratory rim for transporting exhaled gas from the patient. The expiratory rim includes an inlet, an outlet, and a third elongated member containing a second tube with a second lumen. The second lumen is configured to accommodate the bulk flow of exhaled gas, and the second tube is permeable to water vapor and substantially impermeable to liquid water and the bulk flow of exhaled gas.

[0031] The aforementioned breathing circuits may also have one, some, or all of the following properties and any properties described herein. The walls of the exhalation tube may comprise foamed or non-foamed polymers that are permeable to water vapor and substantially impermeable to bulk flows of liquid water and exhaled gases. For the purposes of this disclosure, any material described as "permeable to water vapor and substantially impermeable to bulk flows of liquid water and gases" (or substantially similar wording) is defined herein as a material that allows water vapor molecules to pass through by diffusion, facilitated diffusion, passive transport, active transport or other similar mechanisms for selectively transporting water vapor molecules, but does not have a leak pathway from one outer principal surface of the material to another outer principal surface of the material that allows the passage of bulk flows of liquid water or gases through the leak pathway.

[0032] The foamed polymer may include a solid thermoplastic elastomer material having pores distributed throughout. The non-foamed polymer may include a solid thermoplastic elastomer material that is permeable to water vapor and substantially impermeable to liquid water and bulk flow of exhaled gas. The first lumen of the inspiratory rim may have a smooth bore. The second elongated member of the inspiratory rim may surround at least one heating element. The first elongated member of the inspiratory rim may form a plurality of bubbles in its longitudinal cross-section, having flat surfaces in the lumen. The second elongated member of the inspiratory rim may further include at least one heating element, the at least one inspiratory heating element being positioned between a bubble among the plurality of bubbles and the inspiratory center bore. The third elongated member of the exhalation rim may be corrugated. The first elongated tube may surround a heating element within its lumen. The third elongated member of the exhalation rim may surround a heating element within the second lumen. A third elongated member of the exhalation rim may include a heating element attached to the inner wall of the second tube. The third elongated member of the exhalation rim may include a heating element embedded in the wall of the second tube. The second tube may have an inner surface adjacent to the second lumen, and the exhalation rim may further include a number of reinforcing ribs arranged circumferentially on the inner surface and generally longitudinally aligned between the inlet and outlet. The foamed polymer is preferably selected or manufactured such that the solid thermoplastic elastomer material selectively transports water vapor molecules, but the pores arranged throughout do not form leak pathways that allow the passage of a bulk flow of liquid water or gas through the leak pathways.

[0033] The device may include a breathing circuit. The breathing circuit further includes an inspiratory tube configured to receive an inspiratory gas flow from a gas source. The inspiratory tube includes an inspiratory inlet, an inspiratory outlet, and a wall surrounding an inspiratory central bore, and the inner wall of the inspiratory tube is smooth. The breathing circuit further includes an expiratory tube configured to receive an expiratory gas flow from the patient. The expiratory tube includes an expiratory inlet, an expiratory outlet, and a wall surrounding an expiratory central bore. The inner wall of the expiratory tube is corrugated, and the wall of the expiratory tube is permeable to water vapor and substantially impermeable to liquids and gases flowing through the expiratory tube.

[0034] The aforementioned devices may also have one, some, or all of the following properties and any properties described herein. The walls of the exhalation tube may include a foamed polymer that is permeable to water vapor and substantially impermeable to liquid water and bulk flow of exhaled gas. The inhalation tube may surround a heating element within its central bore or within the walls of the tube. The inhalation tube may include a heating element attached to its walls. The inhalation tube may include a heating element embedded in its walls. The exhalation tube may include a heating element within its central bore. The exhalation tube may include a heating element attached to its inner wall. The exhalation tube may include a heating element embedded within its inner wall. The inspiratory tube may contain multiple bubbles in its longitudinal cross-section that have flat surfaces within the lumen. The intake pipe may include at least one heating element, the at least one intake heating element may be positioned between one of the bubbles and the intake center bore.

[0035] Furthermore, the exhalation tube may include a number of reinforcing ribs arranged circumferentially on its inner surface and generally aligned longitudinally between the inlet and outlet. The breathing circuit may further include a humidifier configured to humidify the inspiratory gas flow delivered to the patient. The humidifier may include a humidifying chamber configured to store a certain amount of liquid and to be in fluid communication with the inspiratory gas flow, and a heater configured to heat a certain amount of liquid in the humidifying chamber to generate vapor so that the inspiratory gas flow is humidified with vapor.

[0036] A respiratory apparatus may include a humidifier, an inspiratory tube, and an expiratory tube. The humidifier is configured to humidify the inspiratory gas flow to the patient. The inspiratory tube is configured to receive the inspiratory gas flow from the humidifier. The inspiratory tube includes an inspiratory inlet, an inspiratory outlet, and a wall surrounding an inspiratory central bore, and the inner wall of the inspiratory tube is smooth. The expiratory tube is configured to receive the expiratory gas flow from the patient. The expiratory tube includes an expiratory inlet, an expiratory outlet, and a wall surrounding an expiratory central bore, the expiratory central bore being corrugated, and the wall of the expiratory tube is permeable to water vapor and substantially impermeable to the bulk flow of liquid and expiratory gas flowing through the expiratory tube.

[0037] The aforementioned breathing apparatus may also have one, some, or all of the following characteristics and any characteristics described herein. The inhalation tube may include at least one heating element within its central bore. The intake pipe may include at least one heating element attached to its inner wall. The intake pipe may include at least one heating element surrounded or embedded within its wall. The exhalation tube may include at least one heating element within the central exhalation bore. The exhalation tube may include at least one heating element attached to its inner wall. The exhalation tube may include at least one heating element embedded within its inner wall. The inhalation tube may include a helically wound member that, in a longitudinal cross-section, forms a plurality of bubbles having a flat surface in the central inhalation bore. The inhalation tube may surround at least one heating element, and at least one inhalation heating element may be positioned between a bubble among a plurality of bubbles and the inhalation center bore. The walls of the exhalation tube may contain foamed or non-foamed polymer.

[0038] The respiratory apparatus may include a humidifier, an inspiratory tube, an expiratory tube, and a control system. The humidifier is configured to humidify the inspiratory gas flow delivered to the patient. The humidifier includes a humidification chamber and a heater. The humidification chamber is configured to store a certain amount of liquid and to be in fluid communication with the inspiratory gas flow. The heater is configured to heat a certain amount of liquid in the humidification chamber to generate vapor so that the inspiratory gas flow is humidified with vapor. The inspiratory tube is configured to receive the humidified inspiratory gas flow from the humidifier. The inspiratory tube includes a wall surrounding an inspiratory central bore, which is smooth. The inspiratory tube further includes a first elongated helical member that, in longitudinal cross-section, forms a plurality of bubbles having flat surfaces in the inspiratory central bore. The bubbles are configured to insulate the inspiratory central bore. The inspiratory tube further includes a second helically wound elongated member joined between adjacent windings of a first elongated member. The second elongated member forms at least a portion of the lumen of the first elongated tube and includes at least one inspiratory heating element embedded within the second elongated member. The expiratory tube is configured to receive an expiratory gas flow from the patient. The expiratory tube includes a conduit surrounding an expiratory central bore, the expiratory central bore being corrugated, and the conduit being permeable to water vapor and substantially impermeable to a liquid flow through the conduit. The expiratory tube further includes at least one expiratory heating element within the expiratory central bore. The control system may be configured to deliver power to a heater of a humidifier. The control system may be configured to deliver power to at least one inspiratory heating element. The control system may be configured to deliver power to at least one expiratory heating element. The control system may be configured to deliver power to the humidifier heater and at least one intake air heating element. The control system may be configured to deliver power to the humidifier heater and at least one exhalation air heating element. The control system may be configured to deliver power to at least one inhalation heating element and at least one exhalation heating element. The control system is configured to deliver power to two or more of the following: the humidifier heater, at least one inhalation heating element, and at least one exhalation heating element. The control system is configured to deliver power to the humidifier heater, at least one inhalation heating element, and at least one exhalation heating element.

[0039] The aforementioned respiratory apparatus may also have one, some, or all of the following characteristics and any characteristics described herein. The walls of the expiratory tube may comprise a foamed or non-foamed polymer that is permeable to water vapor and substantially impermeable to bulk flows of liquid water and exhaled gases. The foamed polymer may comprise a solid thermoplastic elastomer material having pores distributed throughout. The non-foamed polymer may comprise a solid thermoplastic elastomer material that is permeable to water vapor and substantially impermeable to bulk flows of liquid water and exhaled gases. At least one inspiratory heating element may be located between a bubble of a plurality of bubbles and the inspiratory center bore. The respiratory apparatus may further comprise a patient interface assembly between the inspiratory tube and the expiratory tube. Power delivered by the control system may be calculated to provide increased humidification by a humidifier. Power delivered by the control system may be calculated to provide controlled condensate management by at least one expiratory heating element. Power delivered by the control system may be calculated to provide controlled condensate management by at least one inspiratory heating element. The power delivered by the control system may be calculated to provide increased humidification by a humidifier and controlled condensate management by at least one exhalation heating element and at least one inhalation heating element. The breathing apparatus may further include a ventilator configured to supply an inspiratory gas flow and receive an exhalation gas flow. The ventilator may be configured to supply a pulsed inspiratory gas flow to the humidifier. The ventilator may be configured to supply a constant inspiratory gas flow to the humidifier. The ventilator may be configured to supply a biased gas flow.

[0040] The respiratory apparatus may include a humidifier, an inspiratory tube, and an expiratory tube. The humidifier is configured to humidify the inspiratory gas flow to the patient. The inspiratory tube is configured to receive the inspiratory gas flow from a gas source. The inspiratory tube includes an inspiratory inlet, an inspiratory outlet, and a wall surrounding an inspiratory central bore, and the inner wall of the inspiratory tube is smooth. The expiratory tube is configured to receive the expiratory gas flow from the patient. The expiratory tube includes an expiratory inlet, an expiratory outlet, and a wall surrounding an expiratory central bore. The inner wall of the expiratory tube is corrugated, and the wall of the expiratory tube is permeable to water vapor and substantially impermeable to liquids and gases flowing through the expiratory tube. The wall of the expiratory tube may include a foamed polymer that is permeable to water vapor and substantially impermeable to liquid water and bulk flow of expiratory gases. The inspiratory tube may include at least one heating element within its central bore. The respiratory apparatus may also have one, some, or all of the following characteristics and any characteristics described herein. The inspiratory tube may include at least one heating element attached to its inner wall. The inspiratory tube may include at least one heating element surrounded within its wall. The first elongated member of the inspiratory rim may form a plurality of bubbles having a lumen-flat surface in a longitudinal cross-section. The inspiratory tube may surround at least one heating element, and the at least one inspiratory heating element may be between one of the plurality of bubbles and the inspiratory central bore. The expiratory tube may include at least one heating element within the expiratory central bore. The expiratory tube may include at least one heating element attached to its inner wall. The expiratory tube may include at least one heating element embedded within its inner wall. The expiratory tube may include a plurality of reinforcing ribs arranged circumferentially on its inner surface and generally longitudinally aligned between the inlet and outlet. The breathing apparatus may further include a humidifier heater and a control system configured to deliver power to at least one heating element.

[0041] Herein, specific features, aspects, and advantages of this disclosure will be described with reference to the drawings. The drawings and corresponding descriptions are provided to illustrate specific features, aspects, and advantages of this disclosure and do not limit the scope of this disclosure. [Brief explanation of the drawing]

[0042] [Figure 1] This is a schematic diagram of a breathing circuit incorporating one or more medical tubes. [Figure 1A] This is a schematic diagram of a breathing circuit incorporating one or more medical tubes. [Figure 1B] Three graphs are shown illustrating the effect of respiratory circuit compliance on tidal volume error. [Figure 2A] This is a side view of a portion of a composite pipe. [Figure 2B] Figure 2A is a longitudinal cross-sectional view of the composite pipe. [Figure 3A] This is a side view of a portion of a tube incorporating a vapor-permeable foamed polymer material. [Figure 3B] Figure 3A is a cross-sectional view of the pipe. [Figure 4A] This is a front perspective view of a portion of a pipe that has a partially corrugated shape and incorporates integrated reinforcing ribs. [Figure 4B] Figure 4A is a front perspective view of a portion of the pipe, where the pipe as a whole is corrugated. [Figure 5A] This is a front perspective view of a portion of a pipe incorporating ribs. [Figure 5B] Figure 5A is a front perspective view of the pipe. [Figure 6] This is a schematic diagram of a portion of the exhalation tube. [Figure 7] This is a schematic diagram of a portion of the exhalation tube. [Figure 8] This is a schematic diagram of a breathing circuit including a humidifier, an inspiratory tube, and an expiratory tube. [Modes for carrying out the invention]

[0043] A breathing circuit containing one or more medical tubes. To better understand this disclosure, first refer to Figure 1, which shows a breathing circuit 100. Such a breathing circuit 100 may be a respiratory humidification circuit. The breathing circuit 100 includes one or more medical tubes. The breathing circuit 100 may include an inspiratory tube 103 and an expiratory tube 117.

[0044] As used herein, medical tubing is a broad term and should be given its ordinary and conventional meaning to those skilled in the art (i.e., not limited to a special or specialized meaning), and includes, but is not limited to, cylindrical and non-cylindrical elongated shapes that define a lumen or include a passage, such as hollow elongated bodies configured for use in medical procedures and otherwise meeting the standards applicable for such use. An inspiratory tube is a medical tubing configured to deliver respiratory gases to a patient. An exhalation tube is a medical tubing configured to move exhaled gases away from a patient.

[0045] The gas can be transported within the circuit 100 shown in Figure 1. Ambient gas flows from the gas source 105 to the humidifier 107. The humidifier 107 can humidify the gas. The gas source 105 may be a ventilator, a blower or fan, a tank containing compressed gas, a wall-mounted supply unit in a medical facility, or any other suitable breathing gas source.

[0046] The humidifier 107 is connected via a port 111 to the inlet 109 (end for receiving humidified gas) of the inspiratory tube 103, thereby supplying humidified gas to the inspiratory tube 103. The gas flows through the inspiratory tube 103 to the outlet 113 (end for discharging humidified gas) of the inspiratory tube 103, and then flows to the patient 101 via the patient interface 115 connected to the outlet 113. The exhalation tube 117 is connected to the patient interface 115. The exhalation tube 117 returns the humidified gas exhaled from the patient interface 115 to the gas source 105 or the ambient atmosphere. As used herein, patient interface has a broad meaning and should be given to those skilled in the art its usual and conventional meaning, and patient interface also includes, but is not limited to, one or more of the following: a full-face mask, nasal mask, mouth mask, mouth-nasal mask, nasal pillow mask, nasal cannula, nasal prongs, laryngeal mask or any other suitable coupling between a patient's airway and a full-face mask, nasal mask, mouth mask, mouth-nasal mask, nasal pillow mask, nasal cannula, nasal prongs, laryngeal mask or any other suitable medical circuit.

[0047] Gas can enter the gas source 105 through the vent 119. A blower or fan 121 can draw air or other gas through the vent 119 to supply gas to the gas source 105. The blower or fan 121 may be a variable-speed blower or fan. An electronic controller 123 can control the speed of the blower or fan. In particular, the function of the electronic controller 123 may be controlled by an electronic master controller 125. This function may be controlled in response to input from the master controller 125 and a predetermined requested value (preset value) of pressure or user-set blower or fan speed via a dial or other appropriate input device 127.

[0048] The humidifier 107 includes a humidifying chamber 129. The humidifying chamber 129 may be configured to contain a certain amount of water 130 or other suitable humidifying liquid. The humidifying chamber 129 may be removable from the humidifier 107. Removability makes it easier to sterilize or dispose of the humidifying chamber 129 after use. The humidifying chamber 129 portion of the humidifier 107 may be a single unit or may be formed of multiple components joined together to define the humidifying chamber 129. The body of the humidifying chamber 129 may be formed from a non-conductive glass or plastic material. The humidifying chamber 129 may also include conductive components. For example, the humidifying chamber 129 may include a highly thermally conductive base (aluminum base) configured to contact or correspond to a heater plate 131 on the humidifier 107 when the humidifying chamber 129 is mounted on the humidifier 107.

[0049] The humidifier 107 may include an electronic control unit. The humidifier 107 may include an electronic, analog, or digital master controller 125. The master controller 125 may be a microprocessor-based controller that executes computer software commands stored in associated memory. In response to user-defined humidity or temperature values ​​and other inputs entered via a user input device 133, the master controller 125 determines when (or to what level) to energize the heater plate 131 to heat a certain amount of water 130 in the humidification chamber 129.

[0050] The temperature probe 135 can be connected to the inspiratory tube 103 near the patient interface 115, or it can be connected to the patient interface 115. The temperature probe 135 can be integrated into the inspiratory tube 103. The temperature probe 135 detects the temperature near or of the patient interface 115. A temperature-reflecting signal can be provided by the temperature probe 135 to an electronic, analog, or digital master controller 125. A heating element (not shown) can be used to adjust the temperature of the inspiratory tube 103 and / or the patient interface 115 to rise above the saturation temperature, thereby reducing the opportunity for unwanted condensation.

[0051] In Figure 1, the exhaled humidified gas is returned to the gas source 105 through the patient interface 115 and the exhalation tube 117. The exhalation tube 117 may contain a vapor-permeable material, as will be described in more detail below. The vapor-permeable exhalation tube may be wavy.

[0052] The exhalation tube 117 may have a temperature probe and / or heating element, as described above with respect to the inhalation tube 103, in order to reduce the opportunity for condensate to reach the gas source 105. The exhalation tube 117 does not require the exhaled gas to be returned to the gas source 105. The exhaled humidified gas can flow directly into the surrounding environment or into other auxiliary equipment such as an air scrubber / filter (not shown).

[0053] In Figure 1, the intake pipe 103 includes or contains a conduit having a smooth bore. The term smooth bore should be given its usual conventional meaning in the art and includes, but is not limited to, a non-corrugated bore, lumen, or passage. The term smooth bore may be used to describe a pipe having an internal surface that does not have prominent internal corrugations, annular ribs, bumps, or cavities that significantly affect the gas flow in the pipe. The term smooth bore may also be used to describe a pipe that does not have repeating internal surface features that disrupt the substantially laminar flow through a passage or lumen defined by a smooth bore. The term corrugated should be given its usual conventional meaning in the art and includes, but is not limited to, having a raised or grooved surface. Advantageously, a smooth bore results in a conduit having a lower RTF than a conduit of comparable dimensions having a corrugated bore. A smooth bore can reduce the bore (i.e., diameter or cross-sectional area) to reduce flow resistance, resulting in a lower compressive capacity compared to a corrugated pipe with similar flow resistance. An intake conduit may be a composite conduit. A composite conduit can generally be defined as a conduit that includes two or more distinct parts or, more specifically, two or more components joined together to define the conduit. A composite conduit may be spirally wound. A composite conduit can be spirally wound in such a way that two or more components are intertwined in a spiral or joined side-by-side in a spiral configuration.

[0054] The exhalation tube 117 includes or comprises at least a conduit having a vapor-permeable portion. Vapor permeability facilitates humidity removal. At least the vapor-permeable portion of the exhalation tube 117 can be corrugated. The corrugated structure can be on the inside of the tube. The corrugated structure increases the internal surface area of ​​the tube. The amount of vapor that can diffuse through the vapor-permeable material correlates with the surface area of ​​the material in direct contact with the vapor. The corrugated structure also increases the turbulence of the gas within the exhalation tube. Increased turbulence means better mixing of the gases, thereby moving water vapor to the outer wall of the exhalation tube 117. Increased turbulence can increase local residence time within the corrugated structure of the exhalation tube, and this, combined with the vapor permeability characteristics, further improves humidity removal. The increased local residence time also lowers the temperature of the gas swirling in the "pockets" of each corrugated structure compared to that of a smooth-bore tube of the same size, and increases the relative humidity of these gases compared to that of a smooth-bore tube of the same size. An increase in relative humidity increases the vapor pressure gradient across the wall of the exhalation tube 117 compared to a smooth bore tube of the same size, and further increases vapor diffusion through the corrugated wall of the exhalation tube compared to a smooth bore tube of the same size.

[0055] Vapor-permeable corrugated conduits may be formed from foamed or non-foamed polymers that are at least partially permeable to water vapor and substantially impermeable to bulk flows of liquid water and gas. The exhalation tube 117 may include walls that define the space within the exhalation tube 117. At least a portion of the walls may be formed from a foamed material configured to be permeable to water vapor and substantially impermeable to bulk flows of liquid water and gas. At least a portion of the walls may be formed from a non-foamed extruded solid material that is permeable to water vapor and substantially impermeable to bulk flows of liquid water and gas.

[0056] The vapor-permeable exhalation tube 117 may be formed from a non-foam-based material. The non-foam-based material may include a spirally wound vapor-permeable tape, or the non-foam-based material may be extruded into a continuous tube. The corrugated structure of the exhalation tube 117 can be realized using a non-foam-based material. The non-foam-based material may include beads of various diameters arranged in an alternating pattern to form the inner surface of the corrugation. Alternatively, the corrugated structure may be created inside the tube by methods well known in the art, such as molding or stamping.

[0057] The inspiratory tube 103 includes a smooth bore conduit. The smooth bore conduit may be heated and insulated to minimize condensation formation and maximize humidity delivery. Reducing condensation formation in the inspiratory tube allows more vapor in the humidified gas to be delivered to the patient. Several factors affect condensation formation in the inspiratory tube 103, including the internal bore diameter, the smoothness of the internal bore, the level of insulation of the tube, the presence of heating elements (such as wires or elements) associated with the tube 103, and the location of the heating elements within the tube 103 (whether the heating elements are located inside the internal bore of the tube 103 or inside the wall of the tube 103). Specifically, reducing the internal bore diameter of the inspiratory tube 103 increases the velocity of the gas as it moves through the inspiratory tube 103. Increasing the smoothness of the bore reduces turbulence and generates more parabolic wavefronts across the inner wall of the lumen. Therefore, by reducing the internal bore diameter and smoothing the internal bore, the high-speed gas located near the center of the tube will transfer less heat than the low-speed gas located near the tube wall. A smooth-bore tube also does not provide pockets where vapor can be trapped or condensation can accumulate, as in a corrugated tube. Thus, the vapor carried by the gas is encouraged to exit the tube and is therefore delivered to the patient.

[0058] Increasing the degree of insulation of the tube reduces heat loss in the walls of the inhalation tube 103, minimizing condensate formation and maximizing humidity delivery. Furthermore, adding more insulation to the inhalation tube 103 makes the breathing circuit 100 more efficient because the heating element has less to do to maintain the target temperature and humidity. This is because an insulated tube better maintains the temperature and absolute humidity of the gas as it moves through the tube.

[0059] Adding a heating element to the intake pipe 103 also maximizes humidification delivery and reduces condensation. Placing one or more heating elements within the wall of the inhalation tube 103 maximizes humidification, minimizes condensate formation, and contributes to the efficiency of the inhalation tube 103, breathing circuit 100, or humidification system. When the heating elements are located within the wall of the inhalation tube 103, they heat the wall but do not directly heat the gas. Heating the wall reduces the relative humidity of the gas near the wall (heating the gas increases its temperature and decreases its relative humidity). Placing the heating element on the inner side of the inner wall of the insulating “bubble” (defined below) of the intake pipe 103 (described in more detail below) can further reduce heat loss to the outside through the wall of the intake pipe 103, thereby further maximizing humidification and minimizing condensation formation. As used herein, the term “bubble” refers to the cross-sectional shape of a hollow body formed from a long wind or coil of the first long member 203, taken, for example, in the cross-section of the wind or coil as shown in Figure 2B. As used herein, any reference to “bubble” means a long hollow body having a cross-section defined by a wall having a hollow space inside. Referring to Figure 2B, such a shape may include an ellipse or a “D” shape. Such a shape may include, but is not limited to, an “O” shape and other regular and irregular shapes, both symmetrical and asymmetrical.

[0060] The exhalation tube 117 may include corrugated conduits to maximize vapor removal while minimizing condensate formation and increasing local residence time within the corrugated structure. The exhalation tube 117 may include vapor-permeable conduits to maximize vapor removal. The exhalation tube 117 may include heated conduits to maximize vapor removal while minimizing condensate formation. The exhalation tube 117 may include corrugated, vapor-permeable, and / or heated conduits to maximize vapor removal while minimizing condensate formation and increasing local residence time within the corrugated structure. Reduced condensate formation within the exhalation tube 117 allows more vapor to diffuse across the walls of the exhalation tube 117. The presence of a heating element allows the relative humidity of the gas to be maintained below 100% (i.e., the gas temperature to be maintained above the dew point saturation temperature). Placing the heating element near or within the walls of the exhalation tube 117 causes heating of the gas near the walls of the exhalation tube 117. Condensation formation is avoided or limited by keeping the gas temperature near the wall of the exhalation tube 117 above the dew point. The inhalation tube 103 and the exhalation tube 117 will be described in more detail elsewhere in this specification.

[0061] Referring again to Figure 1, the gas source 105 is typically intended to deliver a set amount of gas to the patient 101 with each breath. This set amount may be called the tidal volume or delivery volume. It is desirable that the patient 101 receive the exact amount of gas to reduce the potential risk of lung injury and increase the likelihood of adequate ventilation. When the gas source 105, such as a ventilator, generates the patient's breath, the gas source 105 must fill both the patient's lungs and the breathing circuit 100, which may include a filter, a supply tube from the ventilator to the humidifier, a humidifier chamber, an inspiratory tube, an expiratory tube, and any other components shown or described in relation to Figure 1. Therefore, the gas source 105 must estimate or otherwise take into account the amount of gas used to fill the breathing circuit 100 in order to increase the likelihood of accurate delivery of the amount of gas to the patient and compensate for this.

[0062] The gas source 105 can perform a test on the air compliance of the breathing circuit 100. In this test, the gas source 105 attempts to determine the amount required to generate a specific pressure. Air compliance depends at least on the compressive capacity. The lower the compressive capacity of the breathing circuit 100, the lower the air compliance of the breathing circuit 100 for a given degree of extensibility. The lower the air compliance of the breathing circuit is relative to the patient's lung compliance, the less likely there is to be an error in the tidal volume delivered. If the measurement of the air compliance of the breathing circuit is only slightly off, and the air compliance of the breathing circuit is large compared to the patient's lung compliance, the percentage error in the tidal volume delivered to the patient will be very large. For example, if the measurement of the air compliance of the breathing circuit is 5% off, and the air compliance of the breathing circuit is large compared to the patient's lung compliance, the percentage error in the tidal volume delivered to the patient may be much larger than 5%.

[0063] Figure 1B shows three graphs. The graphs in Figure 1B show the error in tidal volume delivered, with a theoretical 10% error introduced into the gas source measurement of air compliance in the breathing circuit. The three graphs are for three different circuit compliance specifications (e.g., neonatal, adult, and pediatric). In the neonatal circuit, breathing circuit compliance (C bs ) is 0.9 ml.cmH2O -1 It is equal to. In adult circuits, respiratory circuit compliance (C bs ) is 2.1 ml.cmH2O -1 It is equal to. In pediatric circuits, respiratory circuit compliance (C bs ) is 1.3 ml. cmH2O -1 It is equal to. Each graph shows the error in tidal volume delivered in patients with poor respiratory compliance.

[0064] It was found that the error increased significantly as the patient's weight decreased. Patient weight correlates with the target tidal volume. As the patient's weight decreases, the target tidal volume decreases. The comparison of the graphs in Figure 1B shows that, for a given tidal volume, the error increases as respiratory circuit compliance increases. It became clear that, in relation to the lung characteristics of the patient receiving treatment, it is desirable to keep the overall compressive volume and respiratory circuit compliance as low as possible.

[0065] For practical reasons such as minimizing resistance to gas flow in the tube and allowing the tube to be long enough to manage a patient in bed space, the compressive capacity, and therefore compliance, of a breathing circuit tube is usually much greater than that of the patient's lungs. This difference is amplified by certain lung disease conditions that result in the patient having very rigid, low-compliance lungs. The low compressive capacity that may result from short tubes can be a disadvantage from a maneuverability standpoint. Longer tubes and permeable expiratory rims, which benefit from a larger surface area, can be a disadvantage from a compressive capacity standpoint.

[0066] The validity of the compression capacity lies in the fact that trade-offs may exist between the components of the breathing circuit in maintaining a sufficiently low compression capacity. The smooth bore of the inspiratory tube 103 reduces flow resistance, allowing for a reduction in the diameter of the inspiratory tube 103, and therefore a reduction in the compression capacity. This reduction in the compression capacity of the inspiratory tube 103 allows for an increase in the compression capacity of the expiratory tube 117 by increasing its diameter. Increasing the diameter of the expiratory tube 117 increases the surface area of ​​the expiratory tube 117, improving the vapor permeability of the tube 117.

[0067] It was found that by incorporating an inhalation tube 103 with a smaller diameter smooth bore conduit in conjunction with an exhalation tube 117 with a corrugated conduit, the exhalation tube 117 could be made larger in diameter and / or longer than would otherwise be possible, while maintaining the overall compression capacity of the system. Additionally or alternatively, combining a small-diameter smooth-bore inhalation tube 103 with a large-diameter corrugated exhalation tube 117 can maintain the overall pressure loss. Additionally or alternatively, combining an inspiratory tube 103 with a small diameter smooth bore and an expiratory tube 117 with a large diameter corrugated shape allows the flow resistance (RTF) of the breathing circuit 100 to be maintained at a desirable level. Typically, increasing the length of the conduit unnecessarily increases the compressive capacity of the conduit, and therefore the compressive capacity of the overall breathing circuit. Typically, increasing the length of the conduit unnecessarily increases the RTF of the conduit, and therefore increases the RTF of the overall breathing circuit. On the other hand, if the conduit is vapor-permeable, increasing the length advantageously improves the conduit's ability to remove vapor from the exhaled gas. It has been found that combining an inspiratory tube 103 with a small diameter smooth bore and an expiratory tube 117 with a large diameter corrugated vapor-permeable conduit improves the ability of the expiratory tube 117 to remove water vapor from the breathing circuit without increasing the overall compressive capacity, pressure loss, and / or RTF of the system.

[0068] Furthermore, it was recognized that by incorporating an inhalation tube 103 having a smooth bore conduit together with an exhalation tube 117 having a corrugated conduit, the humidifier 107 can improve humidity performance, providing therapeutic benefits to the patient while operating near complete gas saturation, without adding the risk of liquid damaging the gas source 105 or condensates being discharged back to the patient.

[0069] An inhalation tube 103 with a smooth bore and a spirally wound conduit can be paired with an exhalation tube 117 having a corrugated vapor-permeable conduit. As described above, the smooth bore of the inhalation tube 103 has a lower RTF than a corrugated bore of similar size. The smooth bore of the inhalation tube 103 may also have a smaller bore than the corrugated conduit. Normally, reducing the bore reduces the compression capacity and unnecessarily increases the RTF of the inhalation tube. Nevertheless, the smooth bore characteristics can be selected such that the decrease in RTF associated with the smooth bore of the inhalation tube 103 outweighs the increase in RTF resulting from a smaller bore of the inhalation tube 103. This selection of a smaller diameter inhalation tube 103 also reduces the compression capacity of the inhalation tube 103. Therefore, this selection allows the corrugated exhalation tube 117 paired with the smooth bore inhalation tube 103 to be longer and / or have a larger diameter or cross-sectional area without increasing the overall pressure loss or compression capacity of the system. Increasing the length and / or diameter of the expiratory tube 117 typically unnecessarily increases the tube's RTF and compression capacity. However, increasing the length and / or diameter also improves the vapor-permeable tube's ability to remove vapor from the exhaled gas. In this configuration, the performance of the expiratory tube 117 is improved by pairing the smooth-bore inspiratory tube 103 with the corrugated expiratory tube 117. The pressure loss of the breathing circuit system, which may exist from the ventilator outlet to the ventilator inlet, can be influenced by the pressure characteristics (RTF) of each element in the circuit. Referring again to Figure 1, assuming that the pressure characteristics of the supply tubes from the ventilator to the humidifier, humidifier chamber, interface tube, and interface body are constant, the main factors contributing to the system's pressure loss are the flow resistance and dimensions (length and diameter) of the inspiratory tube 103 and expiratory tube 117. Any change to one of these factors should, favorably, be balanced by the others in order to avoid an increase in the system's pressure loss, RTF, and / or compression capacity. As described herein, the main factors contributing to the compressive capacity are the tube profile, extensibility, and dimensions (length and diameter or cross-sectional area) of the inspiratory tube 103 and the expiratory tube 117. A trade-off may exist between reducing the compressive capacity of the inspiratory tube 103 while maintaining the compressive capacity of the breathing circuit, and increasing the compressive capacity of the expiratory tube 117.As described herein, increasing the compression capacity of the exhalation tube 117 is advantageous in terms of vapor permeability of the exhalation rim.

[0070] The smooth bore of the inhalation tube 103 reduces flow resistance (compared to a corrugated inhalation tube), thereby reducing the overall pressure loss of the system. This makes it possible to modify any or all of the other three factors (flow resistance of the corrugated exhalation tube 117 or the dimensions of either tube) to increase the pressure loss of the system. The inner diameter of the inhalation tube 103 can preferably be smaller than that of an equivalent corrugated inhalation tube, thereby increasing the velocity of the gas flowing through the inhalation tube 103. However, a smaller diameter also adds some flow resistance. The length of the corrugated exhalation tube 117 can be increased without increasing the pressure loss of the system, as long as the increase in RTF due to the smaller diameter is sufficiently smaller than the decrease in RTF due to the use of a smooth bore. Increasing the length of the exhalation tube 117 increases the surface area of ​​the tube wall of the exhalation tube 117. The amount of vapor that can diffuse through a vapor-permeable material correlates with the surface area of ​​the material. Increasing the length and / or diameter of the exhalation tube 117 increases the surface area of ​​the walls of the exhalation tube 117, and also increases the residence time of the gas within the exhalation tube 117. The amount of vapor that can diffuse through the permeable material is also correlated with the length of time the vapor-carrying gas is in contact with the material.

[0071] The compression capacity of the breathing circuit (cumulative volume of the entire gas flow path) can be balanced in a similar manner. For example, a change in the dimensions (cross-sectional area or diameter, length) of the inspiratory tube 103 can offset a change in the dimensions (cross-sectional area or diameter, length) of the wavy expiratory tube 117. As described herein, a decrease in the diameter of the inspiratory tube 103 can reduce the compression capacity. This reduction in compression capacity can improve the accuracy of the delivered tidal volume. As described herein, a decrease in the diameter of the inspiratory tube 103 can offset an increase in diameter and / or an increase in the length of the expiratory tube 117. As described herein, a change in the dimensions of the expiratory tube 117 can enhance the function of the expiratory tube 117, for example, by increasing the vapor permeability of the expiratory tube 117. Since changes in tube dimensions affect both the pressure loss and the compression capacity of the system, when making changes, both equations should, advantageously, be balanced or selected simultaneously. Reducing the diameter of the inspiratory tube 103 can increase the average gas velocity in the tube, while increasing flow resistance and reducing the compression capacity. Adding length to the waveform of the exhalation tube 117 increases both flow resistance and compression capacity. Table 1 summarizes the effects of various features on the metrics of these two systems.

[0072] [Table 1]

[0073] Pairing a corrugated expiratory tube 117 with a smooth-bore inspiratory tube 103 can improve the performance of the inspiratory tube 103. Pairing a large-diameter expiratory tube 117 with a small-bore inspiratory tube 103 may be net neutral in terms of compression capacity, but can improve the functionality of the breathing circuit (e.g., by increasing vapor diffusion in the expiratory tube 117). In this configuration, the smooth-bore inspiratory tube 103 minimizes condensate formation and thus maximizes humidity delivery. The overall compression capacity can be reduced by changing dimensions such as the diameter and length of the inspiratory tube 103 and expiratory tube 117. In some configurations, the inspiratory tube 103 is insulated, which helps to make heating elements such as the humidifier 107 and / or heater plate 131 more efficient in generating humidity delivered to the patient 101. The heater plate 131 does not need to function as much, as it does not need to generate such a high target temperature at the humidification chamber port 111. This is because the heated and insulated intake pipe 103 better maintains the absolute humidity of the gas flowing from the humidification chamber port 111 through the intake pipe 103.

[0074] Placing heater wires within the walls of the intake tube 103 also improves the efficiency with which the intake tube 103 maintains the relative humidity of the gas. The heater wires can heat the walls of the intake tube 103 rather than the gas flowing through the lumen of the intake tube 103, thereby reducing the relative humidity of the gas near the walls of the intake tube 103. If the intake tube 103 includes a composite conduit having a spirally wound hollow body, i.e., a "bubble" tube (described in more detail below), the heater wires are located beneath the adiabatic bubble (on the lumen side of the inner wall), thereby reducing heat loss to the outside through the walls of the intake tube 103.

[0075] The smooth bore intake tube 103 facilitates laminar gas flow, generating more parabolic wavefronts across the lumen of the intake tube 103, where gas closer to the center of the lumen has a higher velocity than gas closer to the walls of the intake tube 103. In this configuration, the high-velocity gas has less time to transfer heat to adjacent lower-velocity gas as it passes from the inlet 109 to the outlet 113. Combined with the inward direction of heat generated by the heater wire, this configuration helps to further increase the heat retained by the gas flow.

[0076] The smooth-bore inspiratory tube 103 also does not provide pockets where vapor can be trapped or condensate can accumulate, unlike a corrugated tube. Therefore, the vapor carried by the gas is encouraged to remain in the vapor phase and exit the inspiratory tube 103, and thus be delivered to the patient 101.

[0077] The corrugated exhalation tube 117 maximizes vapor removal and minimizes condensate formation. The exhalation tube 117 can be vapor permeable to facilitate the diffusion of vapor to the outside atmosphere through the walls of the exhalation tube 117. In some configurations, the exhalation tube 117 is vapor permeable and heated, and controlled heating along the tube facilitates the diffusion of vapor to the outside atmosphere through the walls of the exhalation tube 117. The vapor that moves to the outside atmosphere is not delivered to the gas source 105. The corrugated exhalation tube 117 creates turbulence in the portion of the gas flow adjacent to the walls of the exhalation tube 117, increasing the residence time of the gas adjacent to the walls within the corrugated structure. The increased residence time increases the opportunity for vapor diffusion through the walls of the exhalation tube 117. The increased residence time also lowers the temperature of the swirling gas within the "pockets" of each corrugated structure, increasing the relative humidity of these gases. The increased relative humidity increases the vapor pressure gradient across the walls of the exhalation tube 117, further increasing vapor diffusion through the walls.

[0078] As described below, the exhalation tube 117 may include a heater wire wrapped around the center of the lumen of the exhalation tube 117. The heater wire, positioned in this manner, adds turbulence to the gas flow while minimizing condensate formation. Increased turbulence means better mixing of the gases, thereby moving water vapor to the outer wall of the exhalation tube 117. The corrugated exhalation tube 117 also provides corrugated "pockets" that have the advantage of collecting any liquid that condenses from the vapor. The liquid accumulated within the corrugated structure is liquid that is not delivered to the gas source 105. In some configurations, the heater wire can be placed within the wall of the exhalation tube 117. The presence of the heater wire within the exhalation tube 117 also minimizes condensation formation within the exhalation tube.

[0079] The combination of a smooth-bore inspiratory tube 103 and a corrugated expiratory tube 117 allows the humidifier 107 to improve humidity performance. In both invasive and non-invasive ventilation, there are contributions from the patient and bias flow. In both cases, the expiratory tube 117 can function to reduce the amount of humidity returned to the gas source 105. The function of the expiratory tube 117 may be such that it sufficiently reduces the amount of humidity returned to the gas source 105.

[0080] The function of the exhalation tube allows the humidifier 107 and inspiratory tube 103 to deliver a higher level of humidity to the patient 101. If the exhalation tube 117 cannot sufficiently reduce the amount of humidity returned to the gas source 105, the ability of the humidifier 107 and inspiratory tube 103 to deliver a higher level of humidity to the patient 101 will need to be reduced or suppressed, because some of that excess humidity will be carried to the gas source 105 through the exhalation tube 117.

[0081] The applicant has made a surprising discovery related to the breathing circuit: a trade-off may exist between the components of the breathing circuit 100, specifically between the inspiratory tube 103 and the expiratory tube 117, with respect to the overall compression capacity within the system. It was recognized that there may be a reduction in the diameter of the inspiratory tube 103 by switching from a corrugated tube to a smooth bore tube while maintaining the same flow resistance (RTF). Surprisingly, the applicant has found that the diameter of the expiratory tube 117 can be increased to the theoretical maximum nominal diameter while maintaining the overall compression capacity of the breathing circuit. In the corrugated tube, the nominal diameter is equal to the average of the maximum and minimum diameters of the corrugated tube.

[0082] Typical industry-standard corrugated tube diameters for breathing circuits include 10 mm, 15 mm, and 22 mm. In some cases, in the industry, these tube sizes are merely nominal or refer simply to the size of the connector at the end of the tube, rather than the actual inner, outer, and / or nominal diameter of the tube. While not strictly limited, smaller diameter tubes such as 10 mm or 12 mm tubes may be useful for neonatal patients, 15 mm tubes may be useful for pediatric patients, and 22 mm tubes may be useful for adult patients. Other inner or nominal diameters of the tube are possible, including a range of 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, 26 mm, 27 mm, 28 mm, 29 mm, 30 mm and two or more diameters disclosed herein. Assuming that the RTF of the intake rim is constant, it has become clear that the diameter of the intake tube 103 can be reduced if the bore is smooth rather than corrugated.

[0083] Assuming three standard corrugated tube diameters of 10 mm, 15 mm, and 22 mm, it was surprisingly found that flow resistance could be matched between smooth bore tubes of various inner diameters and corrugated tubes of various nominal diameters. Each corrugated tube has an RTF that can be measured by the test apparatus. Each corrugated tube has an RTF that can be theoretically calculated using the tube dimensions. Similarly, each smooth bore tube has an RTF that can be measured by a test apparatus. In addition to or instead of testing, the RTF can be theoretically calculated. For each corrugated tube with a nominal diameter, it has been found that the RTF can be matched to that of a corresponding smaller diameter smooth bore tube. As one non-limiting example revealed by the applicant, based on two tubes having the same RTF, a corrugated tube with a nominal diameter of 10 mm can be substantially equivalent to a smooth bore tube of 6.9 mm. As another example revealed by the applicant, based on substantially similar RTFs, a corrugated tube with a nominal diameter of 15 mm can be substantially equivalent to an 8 mm smooth bore tube. As yet another example revealed by the applicant, based on substantially similar RTFs, a corrugated tube with a nominal diameter of 22 mm can be substantially equivalent to a smooth bore tube of 13.5 mm. Therefore, the smooth bore inspiratory tube 103 can have a reduced diameter compared to a wavy inspiratory tube without increasing the RTF of the inspiratory rim of the breathing circuit.

[0084] The overall compressive capacity of a breathing circuit is interpreted as the sum of the compressive capacity of the inspiratory rim and the compressive capacity of the expiratory rim. Assuming three industry-standard corrugated tube diameters of 10 mm, 15 mm, and 22 mm, the compressive capacity of a breathing circuit can be determined. Each corrugated tube has a compressive capacity that can be measured by a test apparatus. Each corrugated tube has a compressive capacity that can be theoretically calculated based on the dimensions of the corrugated tube. For corrugated tubes, the compressive capacity can be calculated based on the assumption that the nominal diameter of the corrugated tube is equal to the average of the maximum and minimum diameters of the corrugated tube. It was found that the overall compressive capacity of a breathing circuit with corrugated inspiratory and expiratory tubes can be maintained in a breathing circuit 100 where the inspiratory tube 103 has a smooth bore and the expiratory tube is corrugated.

[0085] It was found that changes in the compression capacity of the inspiratory rim can be traded off with changes in the compression capacity of the expiratory rim of the breathing circuit while maintaining the overall compression capacity of the breathing circuit as produced by a standard corrugated tube. It was found that a smooth-bore inspiratory tube 103 can have a reduced diameter while maintaining the RTF of the inspiratory rim. Reducing the diameter of the inspiratory tube of the inspiratory rim (achievable by changing from a corrugated tube to a smooth-bore tube) resulted in a reduction in the compression capacity of the inspiratory rim of the breathing circuit. It was found that this reduction in compression capacity due to the smooth-bore inspiratory tube 103 can be traded off with an increase in the compression capacity of the corrugated expiratory tube 117 while maintaining the overall compression capacity of the breathing circuit. The reduction in the compression capacity of the smooth-bore inspiratory tube 103 can be determined and added to the compression capacity allowance of the expiratory tube 117.

[0086] It has been shown that the expiratory tube 117 can have a theoretical maximum nominal diameter based on the reduction in the compressive capacity of the inspiratory tube 103. As one non-limiting example shown by the applicant, an inspiratory tube 103 with a 6.9 mm smooth bore can offset a 14.7 mm corrugated expiratory tube 117 without changing the overall compressive capacity of the breathing circuit. As another example shown by the applicant, an inspiratory tube 103 with an 8 mm smooth bore can offset a 19.3 mm corrugated expiratory tube 117 without changing the overall compressive capacity of the breathing circuit. As yet another example shown by the applicant, an inspiratory tube 103 with a 13.5 mm smooth bore can offset a 27.4 mm corrugated expiratory tube 117 without changing the overall compressive capacity of the breathing circuit. The theoretical maximum nominal diameter of the corrugated expiratory tube 117 maintains the total compressive capacity of the breathing circuit, which remains unchanged. This is because the reduction in compression capacity due to the design change of the inspiratory tube 103 allows for an increase in compression capacity in the design of the expiratory tube 117.

[0087] It was found that the heater wire in the inspiratory tube 103 adversely affects the RTF (i.e., the heater wire in the inspiratory tube 103 increases the RTF when all other factors are kept constant), and therefore the presence of the heater wire can limit the reduction in diameter of the smooth bore inspiratory tube 103. As one non-limiting example revealed by the applicant, based on the RTF excluding the heater wire, a corrugated tube with a nominal diameter of 10 mm can be substantially equivalent to a 9.3 mm smooth bore tube. Compared to inspiratory and expiratory circuits with a nominal 10 mm corrugated shape, it was found that the inspiratory tube 103 with a 9.3 mm smooth bore can offset the expiratory tube 117 with a 13.4 mm corrugated shape without changing the overall compression capacity of the breathing circuit. As another example revealed by the applicant, based on the RTF excluding the heater wire, a corrugated tube with a nominal diameter of 15 mm can be substantially equivalent to a 12.7 mm smooth bore tube. Compared to inspiratory and expiratory circuits with a nominal 15 mm waveform, it was found that an inspiratory tube 103 with a 12.7 mm smooth bore can offset an expiratory tube 117 with a 16.6 mm waveform without changing the overall compression capacity of the breathing circuit. In yet another example revealed by the applicant, based on the RTF excluding the heater wire RTF, a corrugated tube with a nominal diameter of 22 mm can be substantially equivalent to a 20.3 mm smooth bore tube. Compared to inspiratory and expiratory circuits with a nominal 22 mm waveform, it was found that an inspiratory tube 103 with a 20.3 mm smooth bore can offset an expiratory tube 117 with a 22.9 mm waveform without changing the overall compression capacity of the breathing circuit.

[0088] As another non-limiting example revealed by the applicant, based on the RTF taking into account the heater wire's RTF, a corrugated tube with a nominal diameter of 10 mm can be substantially equivalent to a 5.9 mm smooth bore tube. Compared to inspiratory and expiratory circuits with a nominal 10 mm corrugated tube, it has been found that the inspiratory tube 103 with a 5.9 mm smooth bore can offset the expiratory tube 117 with a 12.8 mm corrugated tube without changing the overall compression capacity of the breathing circuit. A corrugated tube with a nominal diameter of 10 mm can, for example, have a range of 78,539.8 mm 3It may have a nominal compression capacity of / m. The RTF of a corrugated tube with a nominal diameter of 10 mm can be calculated using a trend line. Using the trend line, the smooth bore intake pipe 103 can have a nominal diameter of 5.9 mm, which is the inner diameter of an equivalent smooth bore at the same pressure. In standard tubes and the smooth bore intake pipe 103, the RTF can be the same or approximately the same, for example, 75.93 cmH2O / l / min. The smooth bore intake pipe can be, for example, 27,631.9 mm 3 / m. In such a case, the compression capacity difference can be, for example, 50,907.9 mm 3 / m. The corrugated exhaust pipe 117 can have a total compression capacity that is the sum of the compression capacity of a corrugated tube with a nominal diameter of 10 mm and the compression capacity difference, for example, 129,447.7 mm 3 / m. Thus, the corrugated exhaust pipe 117 can have a maximum nominal diameter of 12.8 mm to maintain the overall compression capacity of the circuit (intake limb and exhaust limb). Additionally or alternatively, the corrugated exhaust limb can have a nominal diameter smaller than the maximum value, and the intake limb and / or the exhaust limb can be extended beyond the length of the prior art. For example, the intake limb and the exhaust limb can be provided with a length such as 1.75 m or other lengths disclosed herein. One skilled in the art will understand that this option, i.e., increasing the length of the intake limb and / or the exhaust limb instead of using the possible maximum exhaust diameter, or increasing the length (of the intake limb and / or the exhaust limb) and increasing it to a diameter smaller than the maximum possible diameter, is available for each embodiment disclosed herein and can be utilized to achieve the beneficial technical effects described herein.

[0089] Another example revealed by the applicant is that, based on the RTF (Return to Force) taking into account the heater wire's RTF (Return to Force), determined using trend lines, a corrugated tube with a nominal diameter of 15 mm can be substantially equivalent to a 6.7 mm smooth bore tube. Compared to inspiratory and expiratory circuits of nominal 15 mm corrugated tubes, it was found that the inspiratory tube 103 with a 6.7 mm smooth bore can offset the expiratory tube 117 with a 20.1 mm corrugated tube without changing the overall compression volume of the breathing circuit. The compression volume of the 15 mm corrugated tube using trend lines is, for example, 176,714.6 mm. 3 It can be / m. Similarly, the intake pipe 103 of the smooth bore is 34,820.4 mm 3 It may have a compression capacity of / m. The difference in compression capacity between a standard tube and a new smooth-bore intake pipe 103 is 141,894.2 mm. 3 This could be / m. The corrugated exhalation tube 117 has a nominal diameter of 15 mm, and the compression capacity of the corrugated tube is the difference in compression capacity, for example, 318,608.8 mm. 3 It may have a total compression capacity which is the sum of / m. Furthermore, since these are values ​​per meter, as will be further described herein, those skilled in the art will understand that the lengths of the inhalation rim and / or exhalation rim can be further increased compared to the length of the rim in the prior art without increasing the overall compression capacity of the circuit.

[0090] Another example revealed by the applicant is that, based on the RTF taking into account the heater wire's RTF as determined by using trendlines, a corrugated tube with a nominal diameter of 22 mm can be substantially equivalent to a 10.9 mm smooth bore tube. Compared to inspiratory and expiratory circuits of a nominal 22 mm corrugated tube, it was found that the inspiratory tube 103 with a 10.9 mm smooth bore can offset the expiratory tube 117 of a 29.1 mm corrugated tube without changing the overall compression volume of the breathing circuit. The compression volume of the 22 mm corrugated tube using trendlines is 380,132.7 mm. 3 It can be / m. The smooth bore intake pipe 103 is 93,664.1 mm 3It may have a compression capacity of / m. The difference in compression capacity between a standard tube and a new smooth-bore intake pipe 103 is 286,468.6 mm. 3 It is possible. The corrugated breathing tube 117 has a nominal diameter of 22 mm, and the compression capacity of the corrugated tube is the same as the compression capacity difference, for example, 666,601.3 mm. 3 It may have a total compression capacity which is the sum of / m. Furthermore, since these are values ​​per meter, as will be further described herein, those skilled in the art will understand that the lengths of the inhalation rim and / or exhalation rim can be further increased compared to the length of the rim in the prior art without increasing the overall compression capacity of the circuit.

[0091] As yet another non-limiting example revealed by the applicant, based on the RTF excluding the heater wire RTF, as determined using trend lines, a corrugated tube with a nominal diameter of 10 mm can be substantially equivalent to a 7.8 mm smooth bore tube. Compared to inspiratory and expiratory circuits of nominal 10 mm corrugated tubes, it was found that the inspiratory tube 103 with a 7.8 mm smooth bore can offset the expiratory tube 117 with an 11.8 mm corrugated tube without changing the overall compressive capacity of the breathing circuit. The compressive capacity of the 10 mm corrugated tube using trend lines is 78,539.8 mm². 3 It can be / m. The intake pipe 103 of the smooth bore is 47,523.4 mm 3 It may have a compression capacity of / m. The difference in compression capacity between a standard tube and a new smooth-bore intake pipe 103 is 31,016.5 mm. 3 It can be / m. The corrugated exhalation tube 117 has a nominal diameter of 10 mm, and the compression capacity of the corrugated tube is the difference in compression capacity, for example, 109,556.3 mm. 3 It may have a total compression capacity which is the sum of / m. Furthermore, since these are values ​​per meter, as will be further described herein, those skilled in the art will understand that the lengths of the inhalation rim and / or exhalation rim can be further increased compared to the length of the rim in the prior art without increasing the overall compression capacity of the circuit.

[0092] Another example revealed by the applicant is that, based on the RTF excluding the heater wire's RTF, a corrugated tube with a nominal diameter of 15 mm can be substantially equivalent to a 10.5 mm smooth bore tube. Compared to inspiratory and expiratory circuits with a nominal 15 mm corrugated tube, it was found that the inspiratory tube 103 with a 10.5 mm smooth bore can offset the expiratory tube 117 with an 18.5 mm corrugated tube without changing the overall compression volume of the breathing circuit. The compression volume of the 15 mm corrugated tube using the trendline is 176,714.6 mm². 3 It is possible. The intake pipe 103 with a smooth bore is 85,910.6 mm 3 It may have a compression capacity of 90,804.0 mm. The difference in compression capacity between a standard tube and a new smooth-bore intake pipe 103 is 90,804.0 mm. 3 It is possible. The corrugated breathing tube 117 has a nominal diameter of 15 mm, and the compression capacity of the corrugated tube is the difference in compression capacity, for example, 267, 518.6 mm. 3 It may have a total compression capacity which is the sum of the above. Furthermore, since these are values ​​per meter, as will be further described herein, those skilled in the art will understand that the lengths of the inhalation rim and / or exhalation rim can be further increased compared to the length of the rim in the prior art without increasing the overall compression capacity of the circuit.

[0093] Another example revealed by the applicant is that, based on the RTF excluding the heater wire's RTF, a corrugated tube with a nominal diameter of 22 mm can be substantially equivalent to a 16.9 mm smooth bore tube. Compared to inspiratory and expiratory circuits of a nominal 22 mm corrugated tube, it was found that the inspiratory tube 103 with a 16.9 mm smooth bore can offset the expiratory tube 117 with a 26.1 mm corrugated tube without changing the overall compression volume of the breathing circuit. The compression volume of the 22 mm corrugated tube using the trendline is 380,132.7 mm. 3 It can be / m. The smooth bore intake pipe 103 is 224,424.7mm 3 It may have a compression capacity of / m. The difference in compression capacity between a standard tube and a new smooth-bore intake pipe 103 is 155,708.0 mm. 3It can be / m. The corrugated exhalation tube 117 has a nominal diameter of 22 mm, and the compression capacity of the corrugated tube and the compression capacity difference, for example, 535, 840.7 mm. 3 It may have a total compression capacity which is the sum of / m. Furthermore, since these are values ​​per meter, as will be further described herein, those skilled in the art will understand that the lengths of the inhalation rim and / or exhalation rim can be further increased compared to the length of the rim in the prior art without increasing the overall compression capacity of the circuit.

[0094] Another example revealed by the applicant is that, based on RTF considering the heater wire's RTF, a corrugated tube with a nominal diameter of 15 mm can be substantially equivalent to a 6.7 mm smooth bore tube. Compared to an inspiratory and expiratory circuit with a nominal 15 mm corrugated tube, it was found that an inspiratory tube 103 with a 6.7 mm smooth bore can offset an expiratory tube 117 with a 20.1 mm corrugated tube without changing the overall compressive capacity of the breathing circuit. Another example revealed by the applicant is that, based on RTF considering the heater wire's RTF, a corrugated tube with a nominal diameter of 15 mm can be substantially equivalent to a 10.0 mm smooth bore tube. Compared to an inspiratory and expiratory circuit with a nominal 15 mm corrugated tube, it was found that an inspiratory tube 103 with a 10.0 mm smooth bore can offset an expiratory tube 117 with an 18.7 mm corrugated tube without changing the overall compressive capacity of the breathing circuit. In another example revealed by the applicant, based on the RTF considering the heater wire's RTF, a corrugated tube with a nominal diameter of 15 mm can be substantially equivalent to a smooth bore tube of 11.7 mm. Compared to an inspiratory and expiratory circuit with a nominal 15 mm corrugated tube, it was found that an inspiratory tube 103 with a smooth bore of 11.7 mm can offset an expiratory tube 117 with a corrugated tube of 17.7 mm without changing the overall compressive capacity of the breathing circuit. In another example revealed by the applicant, based on the RTF considering the heater wire's RTF, a corrugated tube with a nominal diameter of 15 mm can be substantially equivalent to a smooth bore tube of 13.5 mm. Compared to an inspiratory and expiratory circuit with a nominal 15 mm corrugated tube, it was found that an inspiratory tube 103 with a smooth bore of 13.5 mm can offset an expiratory tube 117 with a corrugated tube of 16.4 mm without changing the overall compressive capacity of the breathing circuit. Furthermore, since these are values ​​per meter, as will be further described herein, those skilled in the art should understand that the lengths of the inhalation rim and / or exhalation rim can be further increased compared to the lengths of the rims of the prior art without increasing the overall compression capacity of the circuit.

[0095] The compression volume of a 15mm corrugated tube using trend lines is 176,714.6 mm³. 3 It can be / m. The smooth bore intake pipe 103 is 34,820 mm with a 6.7 mm intake pipe. 3 / m, 78,539.8mm with 10.0mm intake pipe 3 , 107,513.2mm with 11.7mm intake pipe 3 / m and 13.5mm intake pipe for 143, 138.8mm 3 It can have a compression capacity of / m. The difference in compression capacity between a standard tube and a new smooth-bore intake pipe 103 is 141,894.2 mm for a 6.7 mm intake pipe. 3 / m, 98,174.8mm with 10.0mm intake pipe 3 / m, 69,201.4mm with 11.7mm intake pipe 3 / m and 13.5mm intake pipe for 33,575mm 3 It can be / m. The corrugated exhalation tube 117 has a nominal diameter of 15 mm, and the compression capacity of the corrugated tube is 318,608.8 mm, for example, 6.7 mm in the inhalation tube. 3 / m, 274,889.4mm with 10.0mm intake pipe 3 / m, 245,916.0mm with 11.7mm intake pipe 3 / m and 13.5mm intake pipes: 210, 290.4mm 3 It may have a total compression capacity which is the sum of / m. Furthermore, since these are values ​​per meter, as will be further described herein, those skilled in the art will understand that the lengths of the inhalation rim and / or exhalation rim can be further increased compared to the length of the rim in the prior art without increasing the overall compression capacity of the circuit.

[0096] Another example revealed by the applicant is that, based on the RTF excluding the heater wire's RTF, a corrugated tube with a nominal diameter of 15 mm can be substantially equivalent to a 10.5 mm smooth bore tube. It has been revealed that, compared to an inspiratory and expiratory circuit with a nominal 15 mm corrugated tube, the inspiratory tube 103 with a 10.5 mm smooth bore can offset an expiratory tube 117 with an 18.5 mm corrugated tube without changing the overall compressive capacity of the breathing circuit. Furthermore, since these are values ​​per meter, as will be further described herein, those skilled in the art should understand that the lengths of the inspiratory and / or expiratory rims can be further increased compared to the lengths of the rims of the prior art without increasing the overall compressive capacity of the circuit.

[0097] The compression volume of a 15mm corrugated tube using trend lines is 176,714.6 mm³. 3 It can be / m. The smooth bore intake pipe 103 is 85,910.6mm with a 10.5mm intake pipe. 3 It may have a compression capacity of / m. The difference in compression capacity between a standard tube and a new smooth-bore intake pipe 103 is 90,804.0 mm for a 10.5 mm intake pipe. 3 It can be / m. The corrugated exhalation tube 117 has a nominal diameter of 15 mm, and the compression capacity of the corrugated tube is 267, 518.6 mm, for example, 10.5 mm in the inhalation tube. 3 It may have a total compression capacity which is the sum of / m. Furthermore, since these are values ​​per meter, as will be further described herein, those skilled in the art will understand that the lengths of the inhalation rim and / or exhalation rim can be further increased compared to the length of the rim in the prior art without increasing the overall compression capacity of the circuit.

[0098] As an example revealed by the applicant, a trend line may exist for the RTF pressure versus inner diameter of a corrugated tube at 5 L / min. Taking the heater wire into account, one possible equation representing this trend line calculated by the applicant is approximately y = 2149322.2385x -4.4519 , R 2= 0.9727 is possible. One possible formula representing this trend line, calculated by the applicant and excluding the heater line, is approximately y = 603928.0681x -4.4380 , R 2 = 0.9964 is possible. As an example revealed by the applicant, there may be a nominal diameter versus RTF pressure of a corrugated tube at 5 L / min. Taking the heater wire into account, one possible equation representing this trend line calculated by the applicant is approximately y = 26.0327x -0.2185 , R 2 = 0.9727 is possible. One possible formula representing this trend line, calculated by the applicant and excluding the heater line, is approximately y = 20.0518x -0.2245 , R 2 = 0.9964 is possible. The ISO standard limit for RTF at this flow rate is 0.9 cmH2O (88.25 Pa), with two thresholds of 9.78 mm for those with a heater wire and 7.33 mm for those without a heater wire. As an example revealed by the applicant, a trend line of RTF pressure versus bore diameter for a smooth bore tube at 5 L / min may exist. One possible formula representing this trend line calculated by the applicant is approximately y = 15.3164x -0.2191 , R 2 It could be 0.9933.

[0099] Another example revealed by the applicant is the potential trend line between RTF pressure and inner diameter of a corrugated tube at 15 L / min. Taking the heater wire into account, one possible equation representing this trend line calculated by the applicant is approximately y = 22141877.6970x -4.5927 , R 2 = 0.9780 is possible. One possible formula representing this trend line, calculated by the applicant and excluding the heater line, is approximately y = 64442935.7622x -5.5152 , R 2= 0.9907 is possible. As an example revealed by the applicant, there may be a nominal diameter versus RTF pressure of a corrugated tube at 15 L / min. Taking the heater wire into account, one possible equation representing this trend line calculated by the applicant is approximately y = 38.8945x -0.2129 , R 2 = 0.9780 is possible. One possible formula representing this trend line, calculated by the applicant and excluding the heater line, is approximately y = 25.9216x -0.1796 , R 2 = 0.9907 is possible. The ISO standard limit for RTF is 0.9 cmH2O (88.25 Pa), with two thresholds: 14.98 mm for those with a heater wire and 11.59 mm for those without a heater wire. As an example revealed by the applicant, a trend line of RTF pressure versus bore diameter for a smooth bore tube at 15 L / min may exist. One possible formula representing this trend line calculated by the applicant is approximately y = 27.3664x -0.3158 , R 2 It could be 0.9421.

[0100] Another example revealed by the applicant is the potential trend line between RTF pressure and inner diameter of a corrugated tube at 30 L / min. Taking the heater wire into account, one possible equation representing this trend line, calculated by the applicant, is approximately y = 79343411.8635x -4.5906 , R 2 = 0.9657 is possible. One possible formula representing this trend line, calculated by the applicant and excluding the heater line, is approximately y = 528987202.1853x -5.8298 , R 2 = 0.9828 is possible. As an example revealed by the applicant, there may be a nominal diameter versus RTF pressure of a corrugated tube at 30 L / min. Taking the heater wire into account, one possible equation representing this trend line calculated by the applicant is approximately y = 50.3401x -0.2104 , R 2= 0.9657 is possible. One possible formula representing this trend line, calculated by the applicant and excluding the heater line, is approximately y = 30.9550x -0.1686 , R 2 = 0.9828 is possible. The ISO standard limit for RTF is 0.9 cmH2O (88.25 Pa), with two thresholds: 19.61 mm for those with a heater wire and 14.54 mm for those without a heater wire. As an example revealed by the applicant, a trend line of RTF pressure versus bore diameter for a smooth bore tube at 30 L / min may exist. One possible formula representing this trend line calculated by the applicant is approximately y = 26.9650X -0.2260 , R 2 It could be 0.8419.

[0101] It has become clear that the breathing circuit 100 has many advantages. As described herein, a corrugated expiratory tube 117 with a larger nominal diameter increases the surface area and residence time, both of which increase vapor diffusion when the expiratory tube is made of a material that allows the movement of water molecules through the walls of the expiratory tube. When used with a smooth-walled inspiratory tube, the theoretical maximum nominal diameter of the corrugated expiratory tube 117 has the advantage of increasing vapor diffusion during the residence time of the gas in the expiratory tube, while maintaining the overall compressive capacity of the entire breathing circuit.

[0102] The breathing circuit is designed to match the RTF of the inspiratory tube 103 from a corrugated tube of a first nominal diameter to a smooth bore tube of a second diameter, where the second diameter is smaller than the first diameter. The smooth bore tube of the second diameter has a smaller compression volume than the corrugated tube of the first diameter, thereby creating a tolerance for the compression volume of the breathing circuit, which includes the smaller second diameter smooth bore tube as the inspiratory rim. This tolerance for compression volume can be offset by a corrugated tube of a third nominal diameter as the expiratory rim, where the third nominal diameter can be larger than the first nominal diameter. Compared to a breathing circuit having an inspiratory rim with a corrugated tube of a first nominal diameter and an expiratory rim with a corrugated tube of a first nominal diameter, the modified breathing circuit has an inspiratory rim with a smooth bore tube of a second diameter and an expiratory rim with a corrugated tube of a third nominal diameter, and the overall compression capacity between the breathing circuits is the same or less, and the RTF of the inspiratory rim is the same or less. In some embodiments revealed by the applicant, these advantages can be achieved by having a corrugated tube of a third nominal diameter, where the third nominal diameter is larger than the first nominal diameter of the expiratory rim.

[0103] In another example, surprisingly revealed by the applicant, a nominally 13 mm corrugated inspiratory tube and a nominally 13 mm corrugated expiratory tube, when used together to form a breathing circuit, have a compressive capacity. Taking the inspiratory rim as an example, the corrugated inspiratory tube has an RTF that can be measured to obtain an actual RTF or calculated to obtain a theoretical RTF. The RTF of the 13 mm corrugated inspiratory tube can be substantially equal to that of the smooth-bore inspiratory tube 103. The smooth-bore inspiratory tube 103 has a smaller diameter than the corresponding 13 mm corrugated inspiratory tube. This reduction in diameter between the corrugated inspiratory tube and the smooth-bore inspiratory tube 103 corresponds to a reduction in the compressive capacity of the inspiratory rim.

[0104] The inspiratory and expiratory rims together form a breathing circuit. The nominally 13 mm corrugated inspiratory tube and nominally 13 mm corrugated expiratory tube define the first total compressive volume of the breathing circuit. This first total compressive volume can be maintained or reduced in a modified breathing circuit having a smooth-bore inspiratory tube 103. In a modified breathing circuit having a smooth-bore inspiratory tube 103, the inspiratory rim has a reduction in compressive volume due to the reduction in tube diameter. In a modified breathing circuit having a smooth-bore inspiratory tube 103, the expiratory rim may be designed to have a larger nominal diameter. An expiratory rim with a larger nominal diameter has a greater compressive volume that offsets the reduction in the compressive volume of the inspiratory rim when considering the total compressive volume of the breathing circuit. Thus, the reduction in compressive volume obtained from using the smooth-bore inspiratory tube 103 can absorb the increase in compressive volume due to the corrugated expiratory tube 117. A breathing circuit having a nominally 13 mm corrugated inspiratory tube and a nominally 13 mm corrugated expiratory tube has the same or less overall compression capacity as a smooth bore inspiratory tube 103 and a corrugated expiratory tube 117. However, the inspiratory tube 103 has a smaller diameter than the corresponding inspiratory rim of a breathing circuit having a nominally 13 mm corrugated inspiratory tube, and the corrugated expiratory tube 117 has a larger nominal diameter than the corresponding expiratory rim of a breathing circuit having a nominally 13 mm corrugated expiratory tube.

[0105] Tubes of different diameters can be used in different patient populations. Furthermore, the desired delivery or tidal volume may differ not only between tubes of the same or different diameters, but also within the same or different breathing circuits. In some embodiments, smaller diameter tubes may be used in neonatal and pediatric patients, while larger diameter tubes may be used in adult patients. The modified breathing circuit may be suitable for treating patients with a tidal volume in the range of 50 ml to 300 ml. The modified breathing circuit may be suitable for treating patients with a tidal volume of 300 ml or more. The modified breathing circuit may be suitable for treating patients with a tidal volume of 50 ml or less. The modified breathing circuit may be suitable for treating pediatric or adolescent patients. The modified breathing circuit may be suitable for treating adult patients. The modified breathing circuit may be suitable for treating neonatal patients.

[0106] The modified breathing circuit may be tested in accordance with the standard ISO 5367:2014(E), which is incorporated by reference as a whole. For adult patients, the intended delivery volume is 300 ml or more. For pediatric patients, the intended delivery volume is 50 ml to 300 ml. For neonatal patients, the intended delivery volume is 50 ml or less. For adult patients, the flow resistance limit is 0.03 hPa / l / min / m (cmH2O / l / min / m). For pediatric patients, the flow resistance limit is 0.06 hPa / l / min / m (cmH2O / l / min / m). For neonatal patients, the flow resistance limit is 0.37 hPa / l / min / m (cmH2O / l / min / m). For adult patients, the flow rate is 30 L / min. For pediatric patients, the flow rate is 15 L / min. For neonatal patients, the flow rate is 2.5 L / min. Table 1 is reproduced below. The following table may list the flow resistance limits per meter for each patient category of breathing tubes cut to a predetermined length and supplied.

[0107] [Table 2]

[0108] In some advantageous configurations of the modified breathing circuit, the inspiratory tube 103 may have an inner diameter of 5 mm to 14.5 mm, while the expiratory tube 117 may have a nominal inner diameter of 15 mm to 22 mm. In some advantageous configurations of the modified breathing circuit, the inspiratory tube 103 may have an inner diameter of 10 mm to 21 mm, while the expiratory tube 117 may have a nominal inner diameter of 22 mm to 30 mm. In some advantageous configurations, the inspiratory tube 103 may have an inner diameter of 4 mm to 12 mm, while the expiratory tube 117 may have a nominal inner diameter of 13 mm to 18 mm. In some advantageous configurations of the modified breathing circuit, the inspiratory tube 103 may have an inner diameter of 4 mm to 17 mm, while the expiratory tube 117 may have a nominal inner diameter of 10.5 mm to 20.5 mm. In some advantageous configurations of the modified breathing circuit, the inspiratory tube 103 may have an inner diameter of 9.5 mm to 24 mm, while the expiratory tube 117 may have a nominal inner diameter of 19 mm to 31.5 mm. In some advantageous configurations of the modified breathing circuit, the inspiratory tube 103 may have an inner diameter of 3 mm to 13 mm, while the expiratory tube 117 may have a nominal inner diameter of 9.5 mm to 19 mm.

[0109] In some advantageous configurations of the modified breathing circuit, the inspiratory tube 103 may have an inner diameter of 4 mm to 8 mm, while the expiratory tube 117 may have a nominal inner diameter of 11 mm to 15 mm. In some advantageous configurations of the modified breathing circuit, the inspiratory tube 103 may have an inner diameter of 5 mm to 9 mm, while the expiratory tube 117 may have a nominal inner diameter of 18 mm to 22 mm. In some advantageous configurations, the inspiratory tube 103 may have an inner diameter of 9 mm to 13 mm, while the expiratory tube 117 may have a nominal inner diameter of 27 mm to 31 mm. In some advantageous configurations of the modified breathing circuit, the inspiratory tube 103 may have an inner diameter of 6 mm to 10 mm, while the expiratory tube 117 may have a nominal inner diameter of 10 mm to 14 mm. In some advantageous configurations of the modified breathing circuit, the inspiratory tube 103 may have an inner diameter of 8.5 mm to 12.5 mm, while the expiratory tube 117 may have a nominal inner diameter of 16.5 mm to 20.5 mm. In some advantageous configurations of the modified breathing circuit, the inspiratory tube 103 may have an inner diameter of 15 mm to 19 mm, while the expiratory tube 117 may have a nominal inner diameter of 24 mm to 28 mm.

[0110] The intake pipe 103 is within a range of 1 mm to 30 mm, for example, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, 26 mm, 27 mm, 28 mm, 29 mm, 30 mm or any of the aforementioned values, for example, 6 mm The inner diameters may be as follows: m~14mm, 6mm~13mm, 6mm~12mm, 6mm~11mm, 7mm~10mm, 8mm~9mm, 10mm~20mm, 11mm~20mm, 11mm~19mm, 11mm~18mm, 11mm~17mm, 11mm~16mm, 11mm~15mm, 12mm~15mm, 13mm~14mm, 5mm~11mm, 6mm~10mm, 6mm~8mm, 9mm~10mm, etc. The intake pipe 103 may also have an inner diameter of any value between any of these values.

[0111] The intake pipe 103 may have an inner diameter within the ranges of 0mm~2mm, 1mm~3mm, 2mm~4mm, 3mm~5mm, 4mm~6mm, 5mm~7mm, 6mm~8mm, 7mm~9mm, 8mm~10mm, 9mm~11mm, 10mm~12mm, 11mm~13mm, 12mm~14mm, 13mm~15mm, 14mm~16mm, 15mm~17mm, 16mm~18mm, 17mm~19mm, 18mm~20mm, 19mm~21mm, 20mm~22mm, 21mm~23mm, 22mm~24mm, 23mm~25mm, 24mm~26mm, 25mm~27mm, 26mm~28mm, 27mm~29mm, 28mm~30mm, etc. The intake pipe 103 may have an inner diameter within the ranges of 0mm~4mm, 1mm~5mm, 2mm~6mm, 3mm~7mm, 4mm~8mm, 5mm~9mm, 6mm~10mm, 7mm~11mm, 8mm~12mm, 9mm~13mm, 10mm~14mm, 11mm~15mm, 12mm~16mm, 13mm~17mm, 14mm~18mm, 15mm~19mm, 16mm~20mm, 17mm~21mm, 18mm~22mm, 19mm~23mm, 20mm~24mm, 21mm~25mm, 22mm~26mm, 23mm~27mm, 24mm~28mm, 25mm~29mm, 26mm~30mm, etc. The intake pipe 103 may have an inner diameter within the ranges of 0mm~6mm, 1mm~7mm, 2mm~8mm, 3mm~9mm, 4mm~10mm, 5mm~11mm, 6mm~12mm, 7mm~13mm, 8mm~14mm, 9mm~15mm, 10mm~16mm, 11mm~17mm, 12mm~18mm, 13mm~19mm, 14mm~20mm, 15mm~21mm, 16mm~22mm, 17mm~23mm, 18mm~24mm, 19mm~25mm, 20mm~26mm, 21mm~27mm, 22mm~28mm, 23mm~29mm, 24mm~30mm, etc.The intake pipe 103 may have an inner diameter within the ranges of 0mm~8mm, 1mm~9mm, 2mm~10mm, 3mm~11mm, 4mm~12mm, 5mm~13mm, 6mm~14mm, 7mm~15mm, 8mm~16mm, 9mm~17mm, 10mm~18mm, 11mm~19mm, 12mm~20mm, 13mm~21mm, 14mm~22mm, 15mm~23mm, 16mm~24mm, 17mm~25mm, 18mm~26mm, 19mm~27mm, 20mm~28mm, 21mm~29mm, 22mm~30mm, etc. The intake pipe 103 may also have an inner diameter of any value between any of these values.

[0112] The exhalation tube 117 is 1mm to 40mm in diameter, for example, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, 24mm, 25mm, 26mm, 27mm, 28mm, 29mm, 30mm, 31mm, 32mm, 33mm, 34mm, 35mm, 36mm, 37mm, 38mm The nominal inner diameter may be in a range that incorporates m, 39 mm, 40 mm, or any of the aforementioned values, for example, 15.5 mm to 21 mm, 16 mm to 20 mm, 16 mm to 19 mm, 18 mm to 20 mm, 19 mm to 20 mm, 22 mm to 29 mm, 23 mm to 30 mm, 24 mm to 30 mm, 24 mm to 29 mm, 25 mm to 28 mm, 25.5 mm to 27 mm, 13 mm to 17 mm, 14 mm to 17 mm, 15 mm to 16.5 mm, 14 mm to 15 mm, etc. The exhalation tube 117 may also have an inner diameter of any value between any of these values.

[0113] Exhalation tube 117 is 0mm~2mm, 1mm~3mm, 2mm~4mm, 3mm~5mm, 4mm~6mm, 5mm~7mm, 6mm~8mm, 7mm~9mm, 8mm~10mm, 9mm~11mm, 10mm~12mm , 11mm~13mm, 12mm~14mm, 13mm~15mm, 14mm~16mm, 15mm~17mm, 16mm~18mm, 17mm~19mm, 18mm~20mm, 19mm~21mm, 20mm~22m The inner nominal diameter may be within the ranges of 21mm~23mm, 22mm~24mm, 23mm~25mm, 24mm~26mm, 25mm~27mm, 26mm~28mm, 27mm~29mm, 28mm~30mm, 29mm~31mm, 30mm~32mm, 31mm~33mm, 32mm~34mm, 33mm~35mm, 34mm~36mm, 35mm~37mm, 36mm~38mm, 37mm~39mm, 38mm~40mm, etc. Exhalation pipe 117 is 0mm~4mm, 1mm~5mm, 2mm~6mm, 3mm~7mm, 4mm~8mm, 5mm~9mm, 6mm~10mm, 7mm~11mm, 8mm~12mm, 9mm~13mm, 10 mm~14mm, 11mm~15mm, 12mm~16mm, 13mm~17mm, 14mm~18mm, 15mm~19mm, 16mm~20mm, 17mm~21mm, 18mm~22mm, 19mm~23 The inner nominal diameter may be within the range of mm, 20mm~24mm, 21mm~25mm, 22mm~26mm, 23mm~27mm, 24mm~28mm, 25mm~29mm, 26mm~30mm, 27mm~31mm, 28mm~32mm, 29mm~33mm, 30mm~34mm, 31mm~35mm, 32mm~36mm, 33mm~37mm, 34mm~38mm, 35mm~39mm, 36mm~40mm, etc.Exhalation tube 117 is available in the following sizes: 0mm-6mm, 1mm-7mm, 2mm-8mm, 3mm-9mm, 4mm-10mm, 5mm-11mm, 6mm-12mm, 7mm-13mm, 8mm-14mm, 9mm-15mm, 10mm-16mm, 11mm-17mm, 12mm-18mm, 13mm-19mm, 14mm-20mm, 15mm-21mm, 16mm-22mm, 17mm-23mm, 18mm-2 It may have an inner nominal diameter within the range of 4mm, 19mm~25mm, 20mm~26mm, 21mm~27mm, 22mm~28mm, 23mm~29mm, 24mm~30mm, 25mm~31mm, 26mm~32mm, 27mm~33mm, 28mm~34mm, 29mm~35mm, 30mm~36mm, 31mm~37mm, 32mm~38mm, 33mm~39mm, 34mm~40mm, etc. Exhalation tube 117 is available in the following sizes: 0mm-8mm, 1mm-9mm, 2mm-10mm, 3mm-11mm, 4mm-12mm, 5mm-13mm, 6mm-14mm, 7mm-15mm, 8mm-16mm, 9mm-17mm, 10mm-18mm, 11mm-19mm, 12mm-20mm, 13mm-21mm, 14mm-22mm, 15mm-23mm, 16mm-24mm, 17mm- The internal nominal diameter may be within the range of 25mm, 18mm-26mm, 19mm-27mm, 20mm-28mm, 21mm-29mm, 22mm-30mm, 23mm-31mm, 24mm-32mm, 25mm-33mm, 26mm-34mm, 27mm-35mm, 28mm-36mm, 29mm-37mm, 30mm-38mm, 31mm-39mm, 32mm-40mm, etc. The exhalation tube 117 may also have an internal nominal diameter of any value between these values.

[0114] The difference between the diameter of the inspiratory tube 103 and the diameter of the expiratory tube 117 is 0mm to 20mm, for example, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, or any of the aforementioned values. The range to incorporate, for example, 0mm~2mm, 1mm~3mm, 2mm~4mm, 3mm~5mm, 4mm~6mm, 5mm~7mm, 6mm~8mm, 7mm~9mm, 8mm~10mm, 9mm~11mm, 10mm~12mm, 11mm~13mm, 12mm~14mm, 13mm~15mm, 14mm~16mm, 15mm~17mm, 16mm~18mm, 17mm~19mm, 18mm~20mm, 0mm~4mm, 1mm~5mm, 2mm~6mm, 3mm~7mm, 4mm~8mm, 5mm~9mm, 6mm~10mm, 7mm~11mm, 8mm~12mm, 9mm~13mm, 10mm~14mm, 11mm~15mm, 12mm~16mm, 1 3mm~17mm, 14mm~18mm, 15mm~19mm, 16mm~20mm, 0mm~6mm, 1mm~7mm, 2mm~8mm, 3mm~9mm, 4mm~10mm, 5mm~11mm, 6mm~12mm, 7m Possible inner diameters include m~13mm, 8mm~14mm, 9mm~15mm, 10mm~16mm, 11mm~17mm, 12mm~18mm, 13mm~19mm, 14mm~20mm, 0mm~8mm, 1mm~9mm, 2mm~10mm, 3mm~11mm, 4mm~12mm, 5mm~13mm, 6mm~14mm, 7mm~15mm, 8mm~16mm, 9mm~17mm, 10mm~18mm, 11mm~19mm, 12mm~20mm, etc. The inner diameter of the inspiratory tube 103 may be smaller than the nominal inner diameter of the expiratory tube 117. The difference can also be any value between any of these values.

[0115] As another non-limiting but preferred example revealed by the applicant, based on RTF, a corrugated tube having a nominal diameter of 15 mm can be substantially equivalent to a smooth bore tube of 11.7 mm. It has been found that the 11.7 mm smooth bore inspiratory tube 103 can compensate for an expiratory rim of up to 18.5 mm or 20.1 mm (with or without a heater wire, respectively). However, the applicant has surprisingly found that even 14.5 mm, which is less than the maximum diameter used in the corrugated expiratory tube 117, still enables the desired technical effect without an increase in the overall compression capacity of the breathing circuit compared to a nominal 15 mm corrugated inspiratory and expiratory circuit.

[0116] Furthermore, in this preferred example, as further described herein, the lengths of the inspiratory rim and / or expiratory rim can be further increased compared to the prior art or typical rim length without increasing the overall compressive capacity of the circuit. Such increased lengths provide further technical benefits in that such rims have improved maneuverability and improved patient mobility, particularly with respect to neonatal and pediatric patients requiring kangaroo care or other care in which the patient is held. In some embodiments, the inspiratory or expiratory conduit may be about 1.75 m, as described below. A smooth-bore inspiratory tube 103 according to one embodiment of the present invention may have a tube diameter of about 11.7 mm. A smooth-bore inspiratory tube 103 may have a tube length of about 1.75 m. A smooth-bore inspiratory tube 103 may have a tube length of about 188,148 mm 3 It may have a rim compression capacity of / m. The corrugated breathing tube 117 may have a tube diameter of 14.5 mm. The corrugated breathing tube 117 may have a tube length of approximately 1.75 m. The corrugated breathing tube 117 may have a tube length of approximately 288,977 mm 3 It may have a rim compression capacity of / m. The total compression capacity of the smooth-bore inhalation tube 103 and the corrugated exhalation tube 117 is approximately 477,125 mm². 3 It is / m. An equivalent standard tube has a diameter of 15 mm and a length of 1.5 m. The standard tube is a dual-wave circuit typically designed for pediatric patients. In a standard tube, the inspiratory tube may have a tube diameter of 15 mm and a tube length of 1.5 m. The standard inspiratory tube is 265,072 mm. 3It may have a rim compression capacity of 265,072 mm. In a standard tube, the exhalation tube may have a diameter of 15 mm and a length of 1.5 m. A standard exhalation tube has a diameter of 265,072 mm. 3 It can have a rim compression capacity of 530,144 mm². The total compression capacity of the inspiratory and expiratory tubes of a standard circuit is 530,144 mm². 3 / m. As those skilled in the art will understand, compared to a standard circuit, the improved circuit of this embodiment (i.e., 11.7 mm smooth bore inspiratory and 14.5 mm waveform expiratory) allows for greater flow before reaching the ISO standard resistance limit of the 15 mm waveform inspiratory rim (increasing the upper limit size of treatable patients), and the overall compression capacity of the circuit is smaller than that of the 15 mm waveform pair (allowing treatment of patients with lower tidal volumes). Furthermore, the increased length compared to the 1.5 m rim improves patient and caregiver operability and mobility. The larger diameter of the expiratory rim, particularly the breathable rim disclosed herein, increases the residence time and therefore allows for greater removal of moisture to the ambient air (and from sensitive ventilator components that may be damaged by humidity).

[0117] In some embodiments, the smooth-bore inspiratory tube 103 can allow for greater flow before reaching the resistance limit. In some embodiments, this result can increase the upper limit size of treatable patients. In some embodiments, the smooth-bore inspiratory tube 103 can allow for greater flow compared to a standard 15 mm corrugated tube. In some embodiments, the overall circuit compression capacity is smaller than that of a standard corrugated tube pair. In some embodiments, this result can enable the treatment of patients with low tidal volumes with the smooth-bore inspiratory tube 103 and corrugated expiratory tube 117. In some embodiments, the smooth-bore inspiratory tube 103 and corrugated expiratory tube 117 can advantageously allow for greater flow before reaching the resistance limit compared to the corresponding standard circuit. In some embodiments, the smooth-bore inspiratory tube 103 and corrugated expiratory tube 117 can advantageously treat a wider range of patients by increasing the upper limit size of treatable patients compared to the corresponding standard circuit. In some embodiments, the smooth-bore inspiratory tube 103 and the wavy expiratory tube 117 may, advantageously, have a lower overall circuit compression capacity compared to the corresponding standard circuit. In some embodiments, the smooth-bore inspiratory tube 103 and the wavy expiratory tube 117 may, advantageously, treat patients with lower tidal volumes compared to the corresponding standard circuit.

[0118] The intake pipe 103 has a length of 1 m to 4 m, for example, 1.0 m, 1.05 m, 1.1 m, 1.15 m, 1.2 m, 1.25 m, 1.3 m, 1.35 m, 1.4 m, 1.45 m, 1.5 m, 1.55 m, 1.6 m, 1.65 m. m, 1.7m, 1.75m, 1.8m, 1.85m, 1.9m, 1.95m, 2.0m, 2.05m, 2.1m, 2.15m, 2.2m, 2.25m, 2.3m, 2.35m, 2.4m, 2.45m, 2.5 The length may be a range that incorporates m, 2.55, 2.6m, 2.65m, 2.7m, 2.75m, 2.8m, 2.85m, 2.9m, 2.95m, 3.0m, 3.1m, 3.15m, 3.2m, 3.25m, 3.3m, 3.35m, 3.4m, 3.45m, 3.5m, 3.55m, 3.6m, 3.65m, 3.7m, 3.75m, 3.8m, 3.85m, 3.9m, 3.95m, 4.0m, or any of the aforementioned values. The exhalation pipe 117 is 1m to 4m, for example 1.0m, 1.05m, 1.1m, 1.15m, 1.2m, 1.25m, 1.3m, 1.35m, 1.4m, 1.45m, 1.5m, 1.55m, 1.6m, 1.65m , 1.7m, 1.75m, 1.8m, 1.85m, 1.9m, 1.95m, 2.0m, 2.05m, 2.1m, 2.15m, 2.2m, 2.25m, 2.3m, 2.35m, 2.4m, 2.45m, 2.5m The lengths may be in the range of 2.55m, 2.6m, 2.65m, 2.7m, 2.75m, 2.8m, 2.85m, 2.9m, 2.95m, 3.0m, 3.1m, 3.15m, 3.2m, 3.25m, 3.3m, 3.35m, 3.4m, 3.45m, 3.5m, 3.55m, 3.6m, 3.65m, 3.7m, 3.75m, 3.8m, 3.85m, 3.9m, 3.95m, 4.0m, or any of the aforementioned values. Those skilled in the art will recognize that the total length of the inspiratory or expiratory conduit can be disassembled into multiple sections to accommodate other equipment such as a water trap and / or an intermediate connector with one or more sensors and / or a PCB and / or a controller. The length can also be any value between any of these values.

[0119] In some embodiments, lower compliance can allow for a wider range of patient sizes. In some embodiments, lower compliance can allow for longer circuits while still remaining within an acceptable range of patient sizes. In some embodiments, the inspiratory and / or expiratory conduits can be lengthened to a range that incorporates, for example, 1.55m, 1.6m, 1.65m, 1.7m, 1.75m, 1.8m, 1.85m, 1.9m, 1.95m, 2.0m, 2.05m, 2.1m, 2.15m, 2.2m, 2.25m, 2.3m, 2.35m, 2.4m, 2.45m, 2.5m, 2.55m, 2.6m, 2.65m, 2.7m, 2.75m, 2.8m, 2.85m, 2.9m, 2.95m, 3.0m, 1.6m or greater, 1.5 to 2.0mm, preferably 1.75m, preferably 2.0m, or any of the aforementioned values, instead of a length of 1.1 to 1.5m. In some embodiments, longer inspiratory and / or expiratory conduits can be a significant advantage in terms of patient mobility, particularly in the case of neonatal and pediatric patients requiring kangaroo care or other care in which the child is held. In some embodiments, the inspiratory or expiratory conduit may be less than 4 meters long.

[0120] As described herein, the studies investigated the differences in pneumatic characteristics of corrugated and smooth bore tubing used in breathing circuits for delivering humidified gas to and from a patient. The studies examined the pneumatic advantages of a combination of a smooth bore inspiratory rim and a corrugated expiratory rim over conventional corrugated inspiratory and corrugated expiratory rims for three standard tubing sizes: 10 mm, 15 mm, and 22 mm. In some embodiments, the breathing set is a corrugated dual-rim breathing set without a water trap, intended for delivering a humidified gas that may be heated.

[0121] Flow resistance test results showed that, for corrugated tubes of a given nominal diameter (10 mm, 15 mm, and 22 mm), the same flow resistance (RTF) value can be maintained using a smooth bore inspiratory tube of a smaller nominal diameter. In some embodiments, a heater wire is used in the breathing circuit to maintain the temperature of the humidified gas to and from the patient, and in corrugated inspiratory rims, a spirally wound heater wire design is typically used. The heater wire in the air path increases the RTF of the circuit. In some embodiments, the smooth bore inspiratory tube may have a heater wire embedded in the wall of the tube outside the air path so that the heater wire does not affect the RTF. By considering this with respect to RTF measurement, the size of equivalent smooth bore tubes can be further reduced.

[0122] As described herein, a smooth bore inspiratory tube with a smaller nominal diameter directly relates to a reduction in the compression capacity (compliance) of the inspiratory rim. This reduction in compression capacity allows the use of a corrugated expiratory tube with a larger nominal diameter while maintaining equivalent overall breathing set compliance values. In some embodiments, the advantage of a larger expiratory rim surface area is that there is more area over which vapor transfer (air permeability) can occur. For given standard breathing tube sizes of 10 mm, 15 mm, and 22 mm with corrugated inspiratory and expiratory tubes, equivalent combinations of smooth bore inspiratory and corrugated expiratory tubes are described herein. The tests examined three common standard-sized breathing circuits, e.g., breathing sets of 10 mm, 15 mm, and 22 mm.

[0123] To deliver effective respiratory support to patients, several important pneumatic characteristics of breathing sets, such as those described herein, exist. The air compliance of a breathing set includes the sum of the air compliance of all components in the kit. Air compliance can be thought of as a measure of the volume required to raise the pressure within the breathing set to a desired level. A breathing set with low air compliance may require less additional volume for a given pressure change than a breathing set with high air compliance. Air compliance can directly affect the waveform delivery of the ventilator to the patient. In some applications, maintaining or reducing air compliance may be important when treating a given patient population. The air compliance of a breathing tube can be divided into two main components: compressible volume and tube stiffness. A larger internal volume of the circuit results in a larger compressible volume. A larger internal volume means that more air needs to be compressed to raise the pressure. For example, in two steel tubes of the same length, one with an inner diameter of 10 mm and the other with an inner diameter of 20 mm, the compressible volume of the 20 mm tube will be greater than that of the 10 mm tube due to its larger internal volume. The stiffer the pipe wall, the lower the compliance. A stiffer pipe expands and contracts less, and therefore requires less air to reach a given pressure. For example, two pipes of the same length and inner diameter, with the same wall thickness, one made of steel and the other of rubber, will have the same compressive capacity. However, a rubber pipe can expand as the pressure increases, increasing its volume, leading to a greater change in capacity and higher compliance.

[0124] Flow resistance (RTF) can be thought of as a measure of the pressure required to pass a given flow rate of air through a pipe. Flow resistance is usually expressed as cmH2O / l / min. The main pipe properties that affect RTF include pipe diameter and surface roughness. In some embodiments, larger and smoother tubing is advantageous to reduce RTF. Flow resistance can be an important aerodynamic characteristic for a breathing circuit because it limits the magnitude of the waveform / breath that can be delivered to the patient within a given inspiratory time.

[0125] The nominal diameter can be considered a characteristic of the pipe. The nominal diameter is a method that incorporates the difference in the inner diameter of a corrugated pipe. The nominal diameter can be calculated as follows:

number

[0126] One objective of the study was to investigate the effect of smooth bore tubing on the pneumatic characteristics of a breathing circuit, from the perspective of corrugated tubing within the range of tubing sizes typically used in respiratory support therapy. The applicant found that compliance and flow resistance were important characteristics to consider. RTF data were collected for various corrugated and smooth bore tubing. This flow resistance test yielded various trend lines, as described herein. Equivalent smooth bore tubing that yielded the same RTF value was identified using trend lines created by plotting pressure against diameter (or nominal diameter) at a given flow rate for corrugated tubing. This evaluation of flow resistance yielded equivalent RTF between standard corrugated tubing and smooth bore inspiratory tubes. Compliance was calculated for equivalent corrugated and smooth bore tubing. The difference between these compliances was calculated. This compliance comparison test made it possible to investigate the increase in compliance due to smooth bore tubing. The new expiratory rim compliance was obtained by adding the compliance difference found from the above calculation to the original corrugated compliance value. The new maximum expiratory tube diameter could then be calculated from this new value. The compliance of the expiratory rim and the sizing of the tube allow the difference in compliance resulting from using a smooth-bore inspiratory tube to be added to the compliance of the corrugated expiratory tube, thereby increasing the maximum size of the corrugated expiratory tube compared to a standard corrugated tube. Furthermore, since all tests were performed with a single tube cut to a length of 1 m, those skilled in the art will understand that a larger expiratory diameter up to the maximum value calculated herein (this value is greater than the expiratory diameter of the prior art in this type of breathing circuit) can be used, and / or the inspiratory tube and / or expiratory tube can be longer than the length of the prior art breathing circuit.

[0127] During the flow resistance test, a flow sweep was performed on each tube to determine the flow resistance at flow rates from 1.2 to 70 l / min. The test resulted in an understanding of the RTF differences in several different commercially available, typical individual tubes with smooth bore and corrugated internal profiles having various diameters (or nominal diameters). In some cases, the test was performed with a heater wire in the bore, and in other cases, the test was performed without a heater wire in the bore. The tubes were cut to a nominal length of 1 m. Therefore, the RTF values ​​expressed herein are given in mm 3 The unit is / m. The results show that the flow resistance curves of both the corrugated bore tube sample and the smooth bore tube sample are similar. However, when comparing corrugated bore tubes and smooth bore tubes of similar nominal diameter, it can be seen that the smooth bore tube has a lower RTF value for a given flow rate.

[0128] The relationship between the flow resistance of a corrugated bore pipe and the flow resistance of a smooth bore pipe was analyzed to determine the nominal diameter of the smooth bore pipe that produces an RTF value equivalent to that of the corrugated pipe at a given flow rate. In the tests, the flow rates were 5 l / min for a 10 mm pipe, 15 l / min for a 15 mm pipe, and 30 l / min for a 22 mm pipe.

[0129] To understand the pneumatic advantages of switching to a smooth bore tube, the compliance values ​​of equivalent corrugated bore and smooth bore tubes can be compared. The compliance of a breathing rim consists of its compressive capacity and the stiffness of the material. Many different materials can be taken into consideration. As described herein, the compressive capacity aspect of compliance was compared in the tests. The compression capacity can be partially determined by the internal area of ​​the tube. For corrugated tubes, the nominal diameter may be used. The compression capacity can be calculated for standard corrugated tubes and intake tubes with smooth bores. The difference between these values ​​can also be calculated.

[0130] In a given breathing circuit kit including an inspiratory and expiratory rim, the advantage of an inspiratory rim with a lower elasticity and smoother bore is that the expiratory rim can be used for a higher percentage of the kit's total compliance. The new maximum compliance of the expiratory rim may be the sum of the compression volume difference and the compliance of the expiratory rim with a standard waveform. From this calculation, the new maximum nominal diameter of the expiratory rim can be determined.

[0131] The purpose of a heated humidifying breathing circuit is to maintain the humidity of the gas from the chamber to the patient. A heater wire can be installed inside the breathing tube to maintain temperature and reduce humidity condensation along the tube. In some embodiments, the heater wire is a spirally wound filament extending the length of the rim. The heater wire can affect the return-to-fuse flow (RTF) because it restricts the flow. In some embodiments, a smooth bore tube may have an internal heater wire within its wall. The internal heater wire can be removed from the gas path and therefore does not interfere with the RTF.

[0132] To maintain the same flow resistance, a smooth-bore inspiratory tube with a smaller nominal diameter may be used for a corrugated tube of a given nominal diameter. Furthermore, if a helical heater wire is considered in the flow resistance measurement of the corrugated tube, the nominal diameter of an equivalent smooth-bore inspiratory tube can be further reduced to maintain the same flow resistance. As a direct consequence of having a smaller nominal diameter, a smooth-bore inspiratory tube has a lower compression capacity compared to the corresponding standard corrugated tube. A smooth-bore inspiratory tube can allow a higher proportion of the total compliance of the breathing set to be allocated to the expiratory rim, thereby enabling a larger surface area.

[0133] Circuit kits for use in patient respiratory therapy may include a variety of features. A circuit kit includes a breathing circuit. The breathing circuit includes an inspiratory tube for receiving an inspiratory gas flow from a gas source. The inspiratory tube includes an inspiratory inlet, an inspiratory outlet, and an inner wall surrounding an inspiratory central bore. The inner wall of the inspiratory tube is smooth. The breathing circuit includes an expiratory tube for receiving an expiratory gas flow from the patient. The expiratory tube includes an expiratory inlet, an expiratory outlet, and an inner wall surrounding an expiratory central bore. The inner wall of the expiratory tube is corrugated. A circuit kit may include a Y-piece for connecting the inspiratory and expiratory tubes. A circuit kit may include a chamber for holding a certain amount of water and for placement on a humidifier. A circuit kit may include a dryline for transporting flow from a ventilator to another gas source and / or to a humidifier inlet. A circuit kit can be used in a respiratory apparatus system including a gas source such as a respiratory ventilator and / or a humidifier. The system may include a circuit kit and a humidifier.

[0134] The circuit kit may have dimensions based to some extent on the patient population. The inspiratory tube may have an inner diameter of 5 to 14.5 mm, and the expiratory tube may have a nominal inner diameter of 15 to 22 mm. The circuit kit may have dimensions based to some extent on the patient population. The inspiratory tube may have an inner diameter of 4 to 17 mm, and the expiratory tube may have a nominal inner diameter of 10.5 to 20.5 mm. The inspiratory tube may have an inner diameter of 6 mm to 14 mm. The inspiratory tube may have an inner diameter of 6 mm to 13 mm. The inspiratory tube may have an inner diameter of 6 mm to 12 mm. The inspiratory tube may have an inner diameter of 6 mm to 11 mm. The inspiratory tube may have an inner diameter of 7 mm to 10 mm. The inspiratory tube may have an inner diameter of 8 mm to 9 mm. The exhalation tube may have a nominal inner diameter of 15.5 mm to 21 mm. The exhalation tube may have a nominal inner diameter of 16 mm to 20 mm. The exhalation tube may have a nominal inner diameter of 16 mm to 19 mm. The exhalation tube may have a nominal inner diameter of 18 mm to 20 mm. The exhalation tube may have a nominal inner diameter of 19 mm to 20 mm. The inspiratory tube may have an inner diameter of 6 mm to 10 mm. The inspiratory tube may have an inner diameter of 11 mm to 15 mm. The inspiratory tube may have an inner diameter of 9 mm to 13 mm. The inspiratory tube may have an inner diameter of 10 mm to 14 mm. The inspiratory tube may have an inner diameter of 7 mm to 13 mm. The inspiratory tube may have an inner diameter of 8 mm to 14 mm. The exhalation tube may have a nominal inner diameter of 11 mm to 15 mm. The breathing tube may have a nominal inner diameter of 12 mm to 16 mm. The breathing tube may have a nominal inner diameter of 14 mm to 18 mm. The breathing tube may have a nominal inner diameter of 16 mm to 20 mm. The breathing tube may have a nominal inner diameter of 13 mm to 19 mm. The breathing tube may have a nominal inner diameter of 14 mm to 20 mm.

[0135] The difference between the inner diameter of the inspiratory tube and the nominal diameter of the expiratory tube may be 1 mm to 14 mm. The inner diameter of the inspiratory tube can be 1 mm to 14 mm smaller than the nominal diameter of the expiratory tube. The circuit kit may be suitable for treating patients with a tidal volume in the range of 50 ml to 300 ml. The circuit kit may be suitable for treating pediatric and adolescent patients.

[0136] The circuit kit may have dimensions that are based to some extent on the patient population. The inspiratory tube may have an inner diameter of 10-21 mm. The expiratory tube may have a nominal inner diameter of 22-30 mm. The inspiratory tube may have an inner diameter of 9.5-24 mm. The expiratory tube may have a nominal inner diameter of 19-31.5 mm. The inspiratory tube may have an inner diameter of 10-20 mm. The inspiratory tube may have an inner diameter of 11-20 mm. The inspiratory tube may have an inner diameter of 11-19 mm. The inspiratory tube may have an inner diameter of 11-18 mm. The inspiratory tube may have an inner diameter of 11-17 mm. The inspiratory tube may have an inner diameter of 11-16 mm. The inspiratory tube may have an inner diameter of 11-15 mm. The inspiratory tube may have an inner diameter of 12mm to 15mm. The inspiratory tube may have an inner diameter of 13mm to 14mm. The expiratory tube may have a nominal inner diameter of 22mm to 29mm. The expiratory tube may have a nominal inner diameter of 23mm to 30mm. The expiratory tube may have a nominal inner diameter of 24mm to 30mm. The expiratory tube may have a nominal inner diameter of 24mm to 29mm. The expiratory tube may have a nominal inner diameter of 25mm to 28mm. The expiratory tube may have a nominal inner diameter of 25.5mm to 27mm. The inspiratory tube may have an inner diameter of 11mm to 15mm. The inspiratory tube may have an inner diameter of 12mm to 16mm. The inspiratory tube may have an inner diameter of 18mm to 22mm. The inspiratory tube may have an inner diameter of 19mm to 23mm. The inspiratory tube may have an inner diameter of 10mm to 16mm. The inspiratory tube may have an inner diameter of 17mm to 23mm. The expiratory tube may have a nominal inner diameter of 25mm to 29mm. The expiratory tube may have a nominal inner diameter of 26mm to 30mm. The expiratory tube may have a nominal inner diameter of 20mm to 24mm. The expiratory tube may have a nominal inner diameter of 21mm to 25mm. The expiratory tube may have a nominal inner diameter of 24mm to 30mm. The expiratory tube may have a nominal inner diameter of 20mm to 26mm. The difference between the inner diameter of the inspiratory tube and the nominal diameter of the expiratory tube may be 1mm to 20mm. The inner diameter of the inspiratory tube can be 1mm to 20mm smaller than the nominal diameter of the expiratory tube. The circuit kit may be suitable for treating patients with a tidal volume greater than 300ml. The circuit kit may be suitable for treating adult patients.

[0137] The circuit kit may have dimensions based to some extent on the patient population. The inspiratory tube may have an inner diameter of 4-12 mm. The expiratory tube may have a nominal inner diameter of 13-18 mm. The inspiratory tube may have an inner diameter of 3-13 mm and the expiratory tube may have a nominal inner diameter of 9.5-19 mm. The inspiratory tube may have an inner diameter of 5-11 mm. The inspiratory tube may have an inner diameter of 6-10 mm. The inspiratory tube may have an inner diameter of 6 mm to 8 mm. The inspiratory tube may have an inner diameter of 9 mm to 10 mm. The expiratory tube may have a nominal inner diameter of 13 mm to 17 mm. The expiratory tube may have a nominal inner diameter of 14 mm to 17 mm. The expiratory tube may have a nominal inner diameter of 15 mm to 16.5 mm. The exhalation tube may have a nominal inner diameter of 14mm to 15mm. The inspiratory tube may have an inner diameter of 5mm to 9mm. The inspiratory tube may have an inner diameter of 6mm to 10mm. The inspiratory tube may have an inner diameter of 7mm to 11mm. The inspiratory tube may have an inner diameter of 8mm to 12mm. The inspiratory tube may have an inner diameter of 4mm to 11mm. The inspiratory tube may have an inner diameter of 6mm to 12mm. The exhalation tube may have a nominal inner diameter of 13mm to 17mm. The exhalation tube may have a nominal inner diameter of 12mm to 16mm. The exhalation tube may have a nominal inner diameter of 11mm to 15mm. The exhalation tube may have a nominal inner diameter of 14mm to 18mm. The exhalation tube may have a nominal inner diameter of 12mm to 18mm. The expiratory tube may have a nominal inner diameter of 10 mm to 16 mm. The difference between the inner diameter of the inspiratory tube and the nominal diameter of the expiratory tube may be 1 mm to 14 mm. The inner diameter of the inspiratory tube can be 1 mm to 14 mm smaller than the nominal diameter of the expiratory tube. The circuit kit may be suitable for treating patients with a tidal volume of 50 ml or less. The circuit kit may be suitable for treating neonatal patients.

[0138] The inspiratory or expiratory tube may have further features. The inspiratory or expiratory tube may have a length of 1.5 m to 2.5 m. The inspiratory or expiratory tube may have a length of 1.6 m to 2.5 m. The total length of the inspiratory or expiratory tube may be disassembled into multiple sections to accommodate other equipment such as a water trap and / or an intermediate connector with one or more sensors and / or a PCB and / or a controller. The inspiratory tube may surround a heating element within the inspiratory center bore or enclose it within its inner wall. The expiratory tube may contain a heating element. The expiratory tube may be permeable. The inner wall of the expiratory tube may be permeable to water vapor and substantially impermeable to the bulk flow of liquid and exhaled gas flowing through the expiratory tube. The intake pipe may include a plurality of bubbles, each having a flat surface that forms at least a portion of the wall of the intake center bore in a longitudinal cross-section. The system may include a circuit kit and a humidifier.

[0139] Figure 1A shows a breathing circuit 100 that may be similar to Figure 1 as described herein. Such a breathing circuit 100 may be a respiratory humidification circuit. The breathing circuit 100 includes one or more medical tubes. The breathing circuit 100 may include an inspiratory tube 103 and an expiratory tube 117.

[0140] The gas can be transported within the circuit 100 shown in Figure 1A. Ambient gas flows from the gas source 105 to the humidifier 107. The humidifier 107 can humidify the gas. The gas source 105 may be a ventilator, a blower or fan, a tank containing compressed gas, a wall-mounted supply unit in a medical facility, or any other suitable breathing gas source.

[0141] The humidifier 107 is connected to the inlet 109 (the end for receiving humidified gas) of the inspiratory tube 103 via a port 111, thereby supplying humidified gas to the inspiratory tube 103. The gas flows through the inspiratory tube 103 to the outlet 113 (the end for discharging humidified gas) of the inspiratory tube 103, and then flows to the patient 101 via the patient interface 115 connected to the outlet 113. The exhalation tube 117 is connected to the patient interface 115. The exhalation tube 117 returns the humidified gas exhaled from the patient interface 115 to the gas source 105 or the ambient atmosphere.

[0142] Gas can enter the gas source 105 through the vent 119. The blower of the fan 121 can draw air or other gas through the vent 119, thereby supplying gas to the gas source 105. The blower or fan 121 may be a variable-speed blower or fan. The electronic controller 123 can control the speed of the blower or fan. In particular, the functions of the electronic controller 123 may be controlled by the electronic master controller 125. The functions may be controlled in response to input from the master controller 125 and predetermined user-defined values ​​(preset values) of pressure or blower or fan speed via a dial or other appropriate input device 127.

[0143] The humidifier 107 includes a humidifying chamber 129. The humidifying chamber 129 may be configured to contain a certain amount of water 130 or other suitable humidifying liquid. The humidifying chamber 129 may be removable from the humidifier 107. Removability makes it easier to sterilize or dispose of the humidifying chamber 129 after use. The humidifying chamber 129 portion of the humidifier 107 may be a single unit or may be formed of multiple components joined together to define the humidifying chamber. The body of the humidifying chamber 129 may be formed from a non-conductive glass or plastic material. The humidifying chamber 129 may also include conductive components. For example, the humidifying chamber 129 may include a highly thermally conductive base (aluminum base) configured to contact or correspond to the heater plate 131 on the humidifier 107 when the humidifying chamber 129 is mounted on the humidifier 107.

[0144] The humidifier 107 may include an electronic control unit. The humidifier 107 may include an electronic, analog, or digital master controller 125. The master controller 125 may be a microprocessor-based controller that executes computer software commands stored in associated memory. In response to user-defined humidity or temperature values ​​and other inputs entered via a user input device 133, the master controller 125 determines when (or to what level) to energize the heater plate 131 to heat a certain amount of water 130 in the humidification chamber 129.

[0145] As described above, any suitable patient interface can be used for the patient interface 115. The temperature probe 135 can be connected to the inspiratory tube 103 near the patient interface 115, or the temperature probe 135 can be connected to the patient interface 115. The temperature probe 135 can be incorporated into the inspiratory tube 103. The temperature probe 135 detects the temperature near or of the patient interface 115. A temperature-reflecting signal can be provided by the temperature probe 135 to the electronic, analog, or digital master controller 125. A heating element (not shown) can be used to adjust the temperature of the patient interface 115 to rise above its saturation temperature, thereby reducing the chance of unwanted condensation. Alternatively, a heating element 145 can be used to adjust the temperature of the inspiratory tube 103 to rise above its saturation temperature, thereby reducing the chance of unwanted condensation.

[0146] In Figure 1A, the exhaled humidified gas is returned to the gas source 105 through the patient interface 115 and the exhalation tube 117. The exhalation tube 117 may contain a vapor-permeable material, as will be described in more detail below. The vapor-permeable exhalation tube may be wavy.

[0147] The exhalation tube 117 may have a temperature probe and / or heating element, as described above with respect to the inhalation tube 103, in order to reduce the opportunity for condensate to reach the gas source 105. The exhalation tube 117 does not require the exhaled gas to be returned to the gas source 105. The exhaled humidified gas can flow directly into the surrounding environment or into other auxiliary equipment such as an air scrubber / filter (not shown).

[0148] In Figure 1A, the intake pipe 103 encloses or includes a conduit having a smooth bore. Due to the smooth bore, the intake pipe 103 will have a lower RTF than a conduit of comparable dimensions having a corrugated bore. A smooth bore reduces flow resistance, allowing for a reduction in bore (i.e., diameter or cross-sectional area), resulting in a lower compressive capacity compared to a corrugated pipe with similar flow resistance. The intake conduit may be a composite conduit. A composite conduit can generally be defined as a conduit comprising two or more different parts or, more specifically, two or more components joined together to define the conduit. A composite conduit may be spirally wound. A composite conduit may be spirally wound in such a manner that two or more components are spirally intertwined or joined side-by-side in a spiral configuration.

[0149] The exhalation tube 117 includes or comprises at least a conduit having a vapor-permeable portion. Vapor permeability facilitates humidity removal. At least the vapor-permeable portion of the exhalation tube 117 can be corrugated. The corrugated structure can be on the inside of the tube. The corrugated structure increases the internal surface area of ​​the tube. The amount of vapor that can diffuse through the vapor-permeable material correlates with the surface area of ​​the material in direct contact with the vapor. The corrugated structure also increases the turbulence of the gas within the exhalation tube. Increased turbulence means better mixing of the gases, thereby moving water vapor to the outer wall of the exhalation tube 117. Increased turbulence can increase the local residence time within the corrugated structure of the exhalation tube, and this, combined with the vapor permeability characteristics, further improves humidity removal. The increased residence time within the corrugated structure also lowers the temperature of the gas swirling in each corrugated "pocket" compared to that of a smooth-bore tube of the same size, and increases the relative humidity of these gases compared to that of a smooth-bore tube of the same size. An increase in relative humidity increases the vapor pressure gradient across the wall of the exhalation tube 117 compared to a smooth bore tube of the same size, and further increases vapor diffusion through the corrugated wall of the exhalation tube compared to a smooth bore tube of the same size.

[0150] Vapor-permeable corrugated conduits may be formed from foamed or non-foamed polymers that are at least partially permeable to water vapor and substantially impermeable to bulk flows of liquid water and gas. The exhalation tube 117 may include walls that define the space within the exhalation tube 117. At least a portion of the walls may be formed from a vapor-permeable foamed material configured to allow the permeation of water vapor but substantially block the permeation of bulk flows of liquid water and gas. At least a portion of the walls may be formed from a non-foamed extruded solid material that is permeable to water vapor and substantially impermeable to bulk flows of liquid water and gas.

[0151] The vapor-permeable exhalation tube 117 may be formed from a non-foam-based material. The non-foam-based material may include a spirally wound vapor-permeable tape, or the non-foam-based material may be extruded into a continuous tube. The corrugated structure of the exhalation tube 117 can be realized using a non-foam-based material. The non-foam-based material may include beads of various diameters arranged in an alternating pattern to form the inner surface of the corrugation. Alternatively, the corrugated structure may be created inside the tube by methods well known in the art, such as molding or stamping.

[0152] The inspiratory tube 103 includes a smooth bore conduit. The smooth bore conduit may be heated and insulated to minimize condensation formation and maximize humidity delivery. Reducing condensation formation in the inspiratory tube allows more vapor in the humidified gas to be delivered to the patient. Several factors affect condensation formation in the inspiratory tube 103, including the internal bore diameter, the smoothness of the internal bore, the level of insulation of the tube, the presence of heating elements 145 (such as wires or elements) associated with the tube 103, and the location of the heating elements within the tube 103 (whether the heating elements are located inside the internal bore of the tube 103 or inside the wall of the tube 103). Specifically, reducing the internal bore diameter of the inspiratory tube 103 increases the velocity of the gas as it moves through the inspiratory tube 103. Increasing the smoothness of the bore reduces turbulence and generates more parabolic wavefronts across the lumen. Therefore, by reducing the internal bore diameter and smoothing the internal bore, the high-speed gas located near the center of the tube will transfer less heat than the low-speed gas located near the tube wall. A smooth-bore tube also does not provide pockets where vapor can be trapped or condensation can accumulate, as in a corrugated tube. Thus, the vapor carried by the gas is encouraged to exit the tube and is therefore delivered to the patient.

[0153] Increasing the degree of insulation of the tube reduces heat loss in the walls of the inhalation tube 103, maximizing humidity delivery and minimizing condensate formation. Furthermore, adding more insulation to the inhalation tube 103 makes the breathing circuit 100 more efficient because the heating element has less to do to maintain the target temperature and humidity. This is because an insulated tube better maintains the temperature and absolute humidity of the gas as it moves through the tube.

[0154] Adding heating elements to the inhalation tube 103 also maximizes humidification and reduces condensation. Placing one or more heating elements within the wall of the inhalation tube 103 maximizes humidification, minimizes condensation formation, and contributes to the efficiency of the inhalation tube 103, breathing circuit 100, or humidification system. When the heating elements are located within the wall of the inhalation tube 103, they heat the wall but not the gas directly. Heating the wall reduces the relative humidity of the gas near the wall (heating the gas increases its temperature and decreases its relative humidity). Placing heating elements 145 on the inner lumen side of the inner wall of the insulated "bubble" (defined elsewhere) of the inhalation tube 103 (described in more detail below) can further reduce heat loss to the outside through the wall of the inhalation tube 103, thereby further maximizing humidification and minimizing condensation formation.

[0155] The exhalation tube 117 may include a corrugated conduit to maximize vapor removal while minimizing condensate formation and increasing local residence time within the corrugated structure. The exhalation tube 117 may include a vapor-permeable conduit to maximize vapor removal while minimizing condensate formation. The exhalation tube 117 may include a corrugated, vapor-permeable, and / or heated conduit to maximize vapor removal while minimizing condensate formation and increasing local residence time within the corrugated structure. Reduced condensate formation within the exhalation tube 117 allows more vapor to diffuse across the walls of the exhalation tube 117. The presence of the heating element 155 allows the relative humidity of the gas to be maintained below 100% (i.e., the gas temperature to be maintained above the dew point saturation temperature). By positioning the heating element 155 near or within the walls of the exhalation tube 117, the heating element 155 primarily heats the gas near the walls of the exhalation tube 117. Condensation formation is avoided or limited by keeping the gas temperature near the wall of the exhalation tube 117 above the dew point. The inhalation tube 103 and the exhalation tube 117 will be described in more detail elsewhere in this specification.

[0156] It was found that by incorporating an inhalation tube 103 with a smaller diameter smooth bore conduit in conjunction with an exhalation tube 117 with a corrugated conduit, the exhalation tube 117 could be made larger in diameter and / or longer than would otherwise be possible, while maintaining the overall compression capacity of the system. Additionally or alternatively, combining a small-diameter smooth-bore inhalation tube 103 with a large-diameter corrugated exhalation tube 117 can maintain the overall pressure loss. Additionally or alternatively, combining an inspiratory tube 103 with a small-diameter, smooth bore and an expiratory tube 117 with a large-diameter, corrugated bore allows the flow resistance (RTF) of the breathing circuit 100 to be maintained at a desirable level. Typically, increasing the length of the conduit unnecessarily increases the compressive capacity of the conduit, and therefore the compressive capacity of the overall breathing circuit. Typically, increasing the length of the conduit unnecessarily increases the RTF of the conduit, and therefore increases the RTF of the overall breathing circuit. On the other hand, if the conduit is vapor-permeable, increasing the length advantageously improves the conduit's ability to remove vapor from the exhaled gas. It has been found that combining an inspiratory tube 103 with a small-diameter, smooth bore and an expiratory tube 117 with a corrugated, highly vapor-permeable bore improves the ability of the expiratory tube 117 to remove water vapor from the breathing circuit without increasing the overall compressive capacity, pressure loss, and / or RTF of the system.

[0157] Furthermore, it was recognized that by incorporating an inhalation tube 103 having a smooth bore conduit together with an exhalation tube 117 having a corrugated conduit, the humidifier 107 can improve humidity performance, providing therapeutic benefits to the patient while operating near complete gas saturation, without adding the risk of liquid damaging the gas source 105 or condensates being discharged back to the patient.

[0158] An inhalation tube 103 with a smooth bore and a spirally wound conduit can be paired with an exhalation tube 117 having a corrugated vapor-permeable conduit. As described above, the smooth bore of the inhalation tube 103 has a lower RTF than a corrugated bore of similar size. The smooth bore of the inhalation tube 103 may also have a smaller bore than the corrugated conduit. Generally, reducing the bore reduces the compression capacity and unnecessarily increases the RTF of the inhalation tube. Nevertheless, the smooth bore characteristics can be selected such that the decrease in RTF associated with the smooth bore of the inhalation tube 103 outweighs the increase in RTF resulting from a smaller bore of the inhalation tube 103. This selection of a smaller diameter inhalation tube 103 also reduces the compression capacity of the inhalation tube 103. Therefore, this selection allows the corrugated exhalation tube 117 paired with the smooth bore inhalation tube 103 to be longer without increasing the overall system pressure loss and / or compression capacity. Increasing the length of the expiratory tube 117 typically unnecessarily increases the tube's RTF and compression capacity. However, increasing the length also improves the vapor-permeable tube's ability to remove vapor from the exhaled gas. In this configuration, the performance of the expiratory tube 117 is improved by pairing the smooth-bore inspiratory tube 103 with the corrugated expiratory tube 117. The pressure loss of the breathing circuit system that may exist from the ventilator outlet to the ventilator inlet can be affected by the pressure characteristics (RTF) of each element in the circuit. Referring again to Figure 1A, assuming that the pressure characteristics of the supply pipes from the ventilator to the humidifier, humidifier chamber, interface tube, and interface body are constant, the main factors contributing to the system's pressure loss are the flow resistance and dimensions (length and diameter) of the inspiratory tube 103 and expiratory tube 117. Any change to any one of these factors should, favorably, be balanced by the others in order to avoid an increase in the system's pressure loss, RTF, and / or compression capacity. As described herein, the main factors contributing to the compression capacity are the tube profile, extensibility, and dimensions (length and diameter or cross-sectional area) of the inspiratory tube 103 and expiratory tube 117. A trade-off may exist between reducing the compression capacity of the inspiratory tube 103 while maintaining the compression capacity of the breathing circuit and increasing the compression capacity of the expiratory tube 117. As described herein, increasing the compression capacity of the expiratory tube 117 is advantageous in terms of vapor permeability of the expiratory rim.

[0159] The smooth bore of the inhalation tube 103 reduces flow resistance (compared to a corrugated inhalation tube), thereby reducing the overall pressure loss of the system. This makes it possible to modify any or all of the other three factors (flow resistance of the corrugated exhalation tube 117 or the dimensions of either tube) to increase the pressure loss of the system. The inner diameter of the inhalation tube 103 can preferably be smaller than that of an equivalent corrugated inhalation tube, thereby increasing the velocity of the gas flowing through the inhalation tube 103. However, a smaller diameter also adds some flow resistance. The length of the corrugated exhalation tube 117 can be increased without increasing the pressure loss of the system, as long as the increase in RTF due to the smaller diameter is sufficiently smaller than the decrease in RTF due to the use of a smooth bore. Increasing the length of the exhalation tube 117 increases the surface area of ​​the tube wall of the exhalation tube 117. The amount of vapor that can diffuse through a vapor-permeable material correlates with the surface area of ​​the material. Increasing the length of the exhalation tube 117 increases the surface area of ​​the wall of the exhalation tube 117, and also increases the residence time of the gas within the exhalation tube 117. The amount of vapor that can diffuse through the permeable material is also correlated with the length of time the vapor-carrying gas is in contact with the material.

[0160] The compression capacity of the breathing circuit (cumulative volume of the entire gas flow path) can be balanced in a similar manner. For example, a change in the dimensions (cross-sectional area or diameter, length) of the inspiratory tube 103 can offset a change in the dimensions (cross-sectional area or diameter, length) of the wavy expiratory tube 117. As described herein, a decrease in the diameter of the inspiratory tube 103 can reduce the compression capacity. This reduction in compression capacity can improve the accuracy of the delivered tidal volume. As described herein, a decrease in the diameter of the inspiratory tube 103 can offset an increase in diameter and / or an increase in the length of the expiratory tube 117. As described herein, a change in the dimensions of the expiratory tube 117 can enhance the function of the expiratory tube 117, for example, by increasing the vapor permeability of the expiratory tube 117. Since changes in tube dimensions affect both the pressure loss and the compression capacity of the system, when making changes, both equations should, advantageously, be balanced or selected simultaneously. Reducing the diameter of the inspiratory tube 103 can increase the average gas velocity in the tube, while increasing flow resistance and reducing the compression capacity. Adding length to the waveform of the exhalation tube 117 increases both flow resistance and compression capacity. Table 1 (above) summarizes the effects of various features on the metrics of these two systems.

[0161] Pairing a corrugated expiratory tube 117 with a smooth-bore inspiratory tube 103 can improve the performance of the inspiratory tube 103. Pairing a large-diameter expiratory tube 117 with a small-bore inspiratory tube 103 may be net neutral in terms of compression capacity, but can improve the functionality of the breathing circuit (e.g., by increasing vapor diffusion in the expiratory tube 117). In this configuration, the smooth-bore inspiratory tube 103 minimizes condensate formation and thus maximizes humidity delivery. The overall compression capacity can be reduced by changing dimensions such as the diameter and length of the inspiratory tube 103 and expiratory tube 117. In some configurations, the inspiratory tube 103 is insulated, which helps to make heating elements such as the humidifier 107 and / or heater plate 131 more efficient in generating humidity delivered to the patient 101. The heater plate 131 does not need to function as much, as it does not need to generate a high target temperature at the humidification chamber port 111. This is because the heated and insulated intake pipe 103 better maintains the absolute humidity of the gas flowing from the humidification chamber port 111 through the intake pipe 103.

[0162] Placing the heater wire 145 inside the wall of the intake pipe 103 also improves the efficiency of the intake pipe 103 in maintaining the relative humidity of the gas. The heater wire can heat the wall of the intake pipe 103 rather than the gas flowing through the lumen of the intake pipe 103, thereby lowering the relative humidity of the gas near the wall of the intake pipe 103. If the intake pipe 103 includes a composite conduit having a spirally wound hollow body, i.e., a "bubble" tube (described in more detail below), the heater wire 145 is located below the adiabatic bubble (on the lumen side of the inner wall), thereby reducing heat loss to the outside through the wall of the intake pipe 103.

[0163] The smooth bore intake tube 103 facilitates laminar gas flow, generating more parabolic wavefronts across the lumen of the intake tube 103, where gas closer to the center of the lumen has a higher velocity than gas closer to the walls of the intake tube 103. In this configuration, the high-velocity gas has less time to transfer heat to adjacent lower-velocity gas as it passes from the inlet 109 to the outlet 113. Combined with the inward direction of heat generated by the heater wire, this configuration helps to further increase the heat retained by the gas flow.

[0164] The smooth-bore inspiratory tube 103 also does not provide pockets where vapor can be trapped or condensate can accumulate, unlike a corrugated tube. Therefore, the vapor carried by the gas is encouraged to remain in the vapor phase and exit the inspiratory tube 103, and thus be delivered to the patient 101.

[0165] The corrugated exhalation tube 117 maximizes vapor removal and minimizes condensate formation. The exhalation tube 117 can be vapor permeable to facilitate the diffusion of vapor to the outside atmosphere through the walls of the exhalation tube 117. In some configurations, the exhalation tube 117 is vapor permeable and heated, and controlled heating along the tube facilitates the diffusion of vapor to the outside atmosphere through the walls of the exhalation tube 117. The vapor that moves to the outside atmosphere is not delivered to the gas source 105. The corrugated exhalation tube 117 creates turbulence in the portion of the gas flow adjacent to the walls of the exhalation tube 117, increasing the residence time of the gas adjacent to the walls within the corrugated structure. The increased residence time increases the opportunity for vapor diffusion through the walls of the exhalation tube 117. The increased residence time also lowers the temperature of the swirling gas within the "pockets" of each corrugated structure, increasing the relative humidity of these gases. The increased relative humidity increases the vapor pressure gradient across the walls of the exhalation tube 117, further increasing vapor diffusion through the walls.

[0166] As described below, the exhalation tube 117 may include a heater wire 155 wrapped around the center of the lumen of the exhalation tube 117. The heater wire, positioned in this manner, adds turbulence to the gas flow while minimizing condensate formation. Increased turbulence means better mixing of the gases, thereby moving water vapor to the outer wall of the exhalation tube 117. The corrugated exhalation tube 117 also provides corrugated "pockets" that have the advantage of collecting any liquid that condenses from the vapor. The liquid accumulated within the corrugated structure is liquid that is not delivered to the gas source 105. In other configurations, the heater wire may be positioned within the wall of the exhalation tube. The presence of the heater wire 155 in the exhalation tube 117 also minimizes condensate formation within the exhalation tube.

[0167] The combination of a smooth-bore inspiratory tube 103 and a corrugated expiratory tube 117 allows the humidifier 107 to improve humidity performance. In both invasive and non-invasive ventilation, there are contributions from the patient and bias flow. In both cases, the expiratory tube 117 can function to reduce the amount of humidity returned to the gas source 105. The function of the expiratory tube 117 may be such that it sufficiently reduces the amount of humidity returned to the gas source 105.

[0168] The function of the exhalation tube allows the humidifier 107 and inspiratory tube 103 to deliver a higher level of humidity to the patient 101. If the exhalation tube 117 cannot sufficiently reduce the amount of humidity returned to the gas source 105, the ability of the humidifier 107 and inspiratory tube 103 to deliver a higher level of humidity to the patient 101 will need to be reduced or suppressed, because some of that excess humidity will be carried to the gas source 105 through the exhalation tube 117.

[0169] The inspiratory tube 103 and the expiratory tube 117 will be described in more detail below.

[0170] Intake pipe Figure 2A shows a side plan view of one section of the intake conduit 201. Generally, the conduit 201 includes a first elongated member 203 and a second elongated member 205. Member is a broad term and should be given its usual and conventional meaning to those skilled in the art (i.e., not limited to any special or specialized meaning), and includes, but is not limited to, integral parts, integral components and separate components. The first elongated member 203 has a “bubble” profile, while the second elongated member 205 is a structural support member or reinforcing member that adds structural support to the hollow body. As used herein, any reference to “bubble” means an elongated hollow body having a cross-section defined by a wall having a hollow space inside. Referring to Figure 2B, such a shape may include an ellipse or a “D” shape. Such a shape may include, but is not limited to, an “O” shape and other regular and irregular shapes, both symmetrical and asymmetrical. In this specification, the term “bubble” may mean the cross-sectional shape of the elongated wind or coil of the first elongated member 203, taken in a cross-section of the wind or coil, for example, as shown in Figure 2B. The hollow body and structural support members may have a helical configuration as described herein. The conduit 201 may be used to form the intake pipe 103 as described above, a coaxial pipe as described below, or any other pipe as described elsewhere in this disclosure.

[0171] The first elongated member 203 may include a hollow body which is spirally wound to form at least partially an elongated tube having a longitudinal axis LA-LA and a lumen 207 extending along the longitudinal axis LA-LA. A portion 211 of the first elongated member 203 forms at least a portion of the inner wall of the lumen 207. The first elongated member 203 may be a tube. Preferably, the first elongated member 203 is flexible. Flexibility means the ability to bend. Furthermore, the first elongated member 203 is preferably transparent or at least translucent or semi-opaque. Some degree of light transmittance allows a caregiver or user to inspect the lumen 207 for occlusions or contaminants or to confirm the presence of moisture (i.e., condensation). Various plastics, including medical-grade plastics, are suitable for the body of the first elongated member 203. Suitable materials include polyolefin elastomers, polyether block amides, thermoplastic copolyester elastomers, EPDM-polypropylene mixtures, and thermoplastic polyurethanes.

[0172] The hollow structure of the first elongated member 203 contributes to the thermal insulation of the conduit 201. A thermally insulated conduit is desirable to prevent heat loss, as described above. This allows the conduit 201 to deliver gas from the humidifier 107 to the patient 101 while maintaining the controlled state of the gas with minimal energy consumption.

[0173] The second elongated member 205 is also spirally wound and joined to the first elongated member 203 between adjacent windings. The second elongated member 205 forms at least a portion of the lumen 207 of the elongated tube. The second elongated member 205 functions as a structural support for the first elongated member 203. The second elongated member 205 can be wider at the base (proximal to the lumen 207) and narrower at the top. The second elongated member may be approximately triangular, approximately T-shaped, or approximately Y-shaped. However, any shape that matches the contour of the corresponding first elongated member 203 is appropriate.

[0174] Preferably, the second elongated member 205 is flexible to facilitate bending of the pipe. Preferably, the second elongated member 205 has lower flexibility than the first elongated member 203. This improves the ability of the second elongated member 205 to structurally support the first elongated member 203. The second elongated member 205 may be solid or mostly solid.

[0175] The second elongated member 205 can enclose or house a conductive material, such as a filament, specifically one used to generate heat or to carry information from a sensor (not shown). The heating element may include a filament and minimize the low-temperature surface where condensation from moisture-containing gases may form. The heating element may also be used to alter the temperature profile of the gas within the lumen 207 of the conduit 201. The body of the second elongated member 205 can be made of a variety of polymers and plastics, including medical-grade plastics. Suitable materials include polyolefin elastomers, polyether block amides, thermoplastic copolyester elastomers, EPDM-polypropylene mixtures, and thermoplastic polyurethanes. The first elongated member 203 and the second elongated member 205 may be made from the same material.

[0176] Figure 2B shows a longitudinal cross-section of the upper portion of the conduit 201 in Figure 2A. Figure 2B has the same orientation as Figure 2A. The first elongated member 203 may have a hollow shape. The first elongated member 203 may form a plurality of hollow bubbles in its longitudinal cross-section. A portion 209 of the first elongated member 203 overlaps with an adjacent lap of the second elongated member 205. A portion 211 of the first elongated member 203 forms at least a portion of the wall of the lumen 207 (tube bore). Adjacent bubbles can be separated by a gap 213. A second T-shaped elongated member 205, as shown in Figure 2B, can help maintain the gap 213 between adjacent bubbles.

[0177] The first elongated member 203 forms a plurality of hollow bubbles in its longitudinal cross-section.

[0178] One or more conductive materials may be placed within the second elongated member 205 to heat or sense the gas flow. Two heating elements 215 can be enclosed, one on each side of the vertical "T" portion within the second elongated member 205. The heating elements 215 include conductive materials such as aluminum (Al) and / or copper (Cu) alloys or conductive polymers. Preferably, the material forming the second elongated member 205 is selected such that it is nonreactive with the metal in the heating elements 215 when the heating elements 215 reach their operating temperature. The heating elements 215 may be spaced away from the lumen 207 so that the elements are not exposed to the lumen 207. At one end of the composite tube, a pair of elements may form a connecting loop. Multiple filaments may be placed within the second elongated member 205.

[0179] Table 2 shows some non-limiting sample dimensions and some non-limiting sample ranges of the two different composite conduits described herein, one for use in infants and the other for use in adults. Dimensions refer to the cross-section of the conduit. In these tables, lumen diameter represents the inner diameter of the conduit. Pitch represents the distance between two repeating points measured axially along the conduit, i.e., the distance between the tips of adjacent vertical portions of the "T" of the second elongated member 205. Bubble width represents the width (maximum outer diameter) of the bubble. Bubble height represents the height of the bubble from the lumen of the conduit. Bead height represents the maximum height of the second elongated member 205 from the lumen of the conduit (e.g., the height of the vertical portion of the "T"). Bead width represents the maximum width of the second elongated member 205 (e.g., the width of the horizontal portion of the "T"). Bubble thickness represents the thickness of the bubble wall.

[0180] [Table 3]

[0181] Tables 3 and 4 show the characteristics of composite tubes (indicated as "A") as described herein, having a heating element embedded within the second elongated member 205. For comparison, the characteristics of the Fisher & Paykel Model RT100 disposable corrugated tube (indicated as "B"), having a heating element spirally wound inside the bore of the tube, are also shown.

[0182] The flow resistance (RTF) was measured in accordance with Annex A of ISO 5367:2000(E). This publication specifies a normative list of units for expressing the apparatus, procedures, and flow resistance test results by measuring the pressure increase at the rated flow rate of the breathing tube. This includes a distribution for testing breathing tubes supplied ready for use or 1 m long breathing tubes supplied cut to a specified length, and a distribution for individually testing each rim of a dual-rim circuit, including pairs of breathing tubes integrally connected in a Y-piece. The test result is the difference between the pressure measured in a reservoir with a breathing tube attached to the reservoir opening and the pressure measured in a reservoir without a breathing tube attached to the reservoir opening.

[0183] The results are summarized in Table 3. As shown below, the RTF of the composite pipe is lower than that of the pipe of the equivalent size model RT100.

[0184] [Table 4]

[0185] Condensate or "droplet deposition" in the tube refers to the weight of condensate recovered per day at a gas flow rate of 20 L / min and room temperature of 18°C. Humidified air flows continuously from the chamber through the tube. The weight of the tube is recorded before and after each day of testing. Three consecutive tests are conducted with the tube dried during each test. The results are shown in Table 4 below. The results showed that droplet deposition was significantly lower in the composite tube than in the tube of the equivalent-sized Model RT100.

[0186] [Table 5]

[0187] The composite tube 201 may include one or more heating filaments 215 arranged within the gas path. The heating filaments can be positioned on the inner wall (tube bore) in a helical configuration. One or more heating filaments 215 can be positioned on the inner wall by bonding, embedding, or the heating filaments can be formed by another method on the surface of a second elongated member 205 that, when assembled, forms the inner wall. Thus, the method may include positioning one or more heating filaments 215 on the inner wall.

[0188] Further details relating to composite conduits suitable for intake tube 103 are disclosed in the specifications and drawings of U.S. Patent Application Publication No. 14 / 123,485, published as U.S. Patent Application Publication No. 2014 / 0202462A1, and U.S. Patent Application Publication No. 14 / 649,801, published as U.S. Patent Application Publication No. 2015 / 0306333A1, all of which are incorporated herein by reference.

[0189] Exhalation tube As explained above with respect to Figure 1, the breathing circuit can utilize a vapor-permeable (i.e., breathable) exhalation tube to handle exhaled gas with high relative humidity. Breathability is desirable to increase vapor diffusion and thereby prevent water droplet precipitation (condensation) within these components. Therefore, the breathing circuit may include a vapor-permeable exhalation tube. Generally, an exhalation tube includes an inlet (for receiving exhaled gas), an outlet (for expelling the received gas), and a sealed wall defining at least one gas passage between the inlet and the outlet, at least a portion of which is made of a vapor-permeable material that allows the permeation of water vapor but substantially blocks the permeation of liquid water and bulk flow of breathing gas. The exhalation tube may be terminated by a first connector at the inlet and a second connector at the outlet, providing only one gas passage over the length between the inlet connector and the outlet connector.

[0190] The wall, due to its breathability or vapor permeability, forms a water vapor path from the gas space within the pipe to the area on the other side of the wall, which may be ambient air. Preferably, the vapor-permeable portion of the sealed wall is formed of a foamed material. The pipe may include an extruded corrugated conduit.

[0191] Exhalation tubes containing vapor-permeable foamed polymers have been found to be advantageously breathable and robust. The exhalation tube may include a wall defining an internal space, at least a portion of which is made of a vapor-permeable foamed material that allows the permeation of water vapor from the gas in the space but prevents the permeation of liquid water. The entire sealed wall may be formed of the foamed material. Preferably, the wall is also impermeable to the bulk flow of gas in the space containing the breathing gas. Due to its vapor permeability, the wall forms a water vapor pathway from the gas space to the region beyond the wall.

[0192] Next, refer to Figures 3A and 3B, which show the conduit 301 of the respiratory tube. Figure 3A shows a side view of the conduit 301, and Figure 3B shows a cross-sectional view of the conduit 301 along the same side view as in Figure 3A. In both Figures 3A and 3B, the horizontal axis is shown as line 303-303. The conduit wall, shown as wall 305 in Figure 3B, is a vapor-permeable foamed material. As shown in the figure, the conduit 301 is corrugated. The tube wall, shown as wall 305 in Figure 3B, is a breathable foamed material as described above.

[0193] Since tubes are a type of component, the details of the components described above are also applicable to the tubes described herein. At least a portion of the sealed wall may contain a permeable foamed material that allows the permeation of water vapor but substantially prevents the permeation of liquid water and bulk flows of breathing gases. The tube may be an extruded corrugated tube. Medical circuit tubes can be used as breathing tubes or conduits or tubes or conduits for the rim of an air supply system. For example, the tubes may be an expiratory breathing tube or an exhaust conduit, respectively. The tubes may also be part of a patient interface. Conduit 301 may be used to form an expiratory tube 117 as described above, a coaxial tube as described below, or any other tube as described elsewhere in this disclosure.

[0194] By incorporating highly permeable or vapor-permeable foamed or non-foamed materials, components with both relatively high flexural stiffness and high permeability can be manufactured. Foamed polymers, due to their high vapor permeability (permeability), allow water vapor to rapidly diffuse through them. This reduces condensate buildup in the exhaled tube by allowing water vapor from the humidifying gas in the exhaled tube to permeate into the surrounding ambient air or another dryer gas on the other side of the component. Nevertheless, components formed from these foamed polymers are also rigid, self-supporting, shatterproof or semi-rigid, with relatively high resistance to crushing and buckling, and may not require further reinforcement. Because foamed polymers allow the permeation of water vapor from gases but prevent the permeation of liquid water, foamed polymers are useful for forming components in medical circuits. Foamed polymers are also substantially impermeable to bulk gas flows, so they can be used to form components for delivering humidifying gases. The foamed polymer may be selected to be vapor permeable, while its “bulk” properties (thickness, material, material composition, modulus, permeability, and / or bulk stiffness) meet the requirements of the ISO 5367:2000(E) standard (i.e., the test for increased flow resistance) without additional reinforcement. ISO 5367:2000(E) is incorporated herein by reference in its entirety.

[0195] Preferably, the foamed polymer is a vapor-permeable foamed thermoplastic polymer. The vapor-permeable thermoplastic polymer may be a foamed thermoplastic elastomer (or TPE as defined by ISO 18064:2003(E)), for example (1) a copolyester thermoplastic elastomer (e.g., ARNITEL®, which is a copolyester thermoplastic elastomer having polyether soft segments, or other TPC or TPC-ET materials as defined by ISO 18064:2003(E)), or (2) a polyether block amide (e.g., PEBAX®, which is a polyamide thermoplastic elastomer having polyether soft segments, or other TPA-ET materials as defined by ISO 18064:2003(E)), or (3) a thermoplastic polyurethane (TPU material as defined by ISO 18064:2003(E)), or (4) a foamed polymer blend such as a TPE / polybutylene terephthalate (PBT, e.g., DURANEX® 500FP) blend. The vapor-permeable TPE ARNITEL® VT3108 has been found to be particularly suitable for foamed and molded components. In this material, the relationship between permeability and strength can be greatly improved by foaming the material when it is molded into a product or component. When the permeable thermoplastic polymer is a foamed TPE / PBT blend, the blend preferably contains 80% to 99% (or about 80% to 99%) TPE by weight and 20% to 1% (or about 20% to 1%) PBT by weight. The porosity of the foamed material can be greater than 25% (or about 25%), such as 25% to 60% (or about 25% to 60%) or 30% to 50% (or about 30% to 50%). The foamed material can be structured such that 5% (or about 5%) or less of the voids in the foamed material have a diameter greater than 500 μm.

[0196] The combination of permeability and elastic modulus for all conventionally known materials is given by the formula: 1n(P) = 0.019(1n(M)). 2It was found that the value did not exceed line 201, which indicates -0.71n(M))+6.5. In the formula, P is the transmittance of the material measured according to ASTM E96 procedure A (drying method at a temperature of 23°C and relative humidity of 90%) in g·mm / m2 / day, and M is the Young's modulus of the material in MPa.

[0197] The breathing circuit may include an exhalation tube containing a non-foam-based corrugated material and / or vapor-permeable material. In some non-limiting configurations, the inner wall of the exhalation tube may include a spirally wound vapor-permeable tape, or the non-foam-based material may be extruded into a continuous tube. In some configurations, the inner wall of the exhalation tube may include a series of beads of various diameters. Beads of different diameters may be arranged along the inner wall of the exhalation tube to create a corrugated pattern. Alternatively, the corrugated structure may be created within the tube by methods well known in the art, such as molding or stamping.

[0198] The wall may also include at least one reinforcing rib that reinforces the wall or at least one area where the wall is locally thickened to reinforce the wall. The tube may include a plurality of reinforcing ribs arranged around the sealed wall. These ribs may be co-extruded with the tube so as to be roughly aligned with the longitudinal axis of the tube. Preferably, there are 3 to 8 reinforcing ribs, particularly 3 to 5 reinforcing ribs.

[0199] Next, we refer to Figures 4A and 4B, which show portions of the conduit 301 that may be used to form the exhalation tube 117. The conduit 301 may be manufactured from a foamed vapor-permeable material as described herein. The conduit 301 further includes a number of reinforcing ribs 403 that may be co-extruded with the conduit 301. The ribs 403 may be formed from the same foamed polymer as the conduit 301. Alternatively, the ribs 403 may be made from a different material than the conduit 301. This can be achieved by co-extrusion. As shown in Figure 4A, the conduit 301 may be extruded with the ribs 403 in place, and then corrugated to form the “dotted” structure shown in Figure 4B. The conduit 301 may include 3 to 8 reinforcing ribs, for example, 3 to 5 reinforcing ribs.

[0200] In particular, ribs may be positioned around the periphery of the tubular shape. Ribs may be positioned circumferentially on the inner surface of the tubular shape. Ribs may be aligned roughly longitudinally along the length of the tubular shape between the inlet and outlet.

[0201] Next, refer to Figures 5A and 5B, which show the configuration of the ribbed vapor permeable conduit 301 in waveform. In Figure 5, the raised ribs 403 are visible in the space between the ridges inside the conduit 301.

[0202] In addition to the above, heaters such as resistance heater wires may be provided inside the passage of the conduit 301, inside the wall of the conduit 301, or around the outer surface of the outer wall surface of the conduit 301 in order to reduce or eliminate the formation of condensates inside the pipe. Figure 6 is an overall view of a corrugated foamed polymer conduit 301 with heater wires 601 incorporated inside the passage of the conduit 301. Figure 7 is an overall view of a corrugated foamed polymer conduit 301 with heater wires 601 incorporated around the outer surface of the outer wall surface of the conduit 301. Figure 8 includes a schematic diagram of an exhalation tube 117 with heater wires 601 incorporated inside the pipe wall.

[0203] Further details relating to the exhalation tube are disclosed in the specification and drawings of U.S. Patent Application Publication No. 13 / 517,925, published as U.S. Patent Application Publication No. 2013 / 0098360A1, and all of the contents thereof are incorporated herein by reference.

[0204] Further reference is made to Figure 8, which shows a breathing circuit including an inspiratory tube 103 and an expiratory tube 117. The characteristics of the inspiratory tube 103 and the expiratory tube 117 are similar to those described above with respect to Figures 1 to 7. The inspiratory tube 103 has an inlet 109 that communicates with a humidifier 107 and an outlet 113 through which humidified gas is supplied to the patient 101. The expiratory tube 117 also has an inlet 109 that receives exhaled gas from the patient 101 and an outlet 113. As described above with respect to Figure 1, the outlet 113 of the expiratory tube 117 can discharge the exhaled gas to the atmosphere, a gas source 105, an air scrubber / filter (not shown), or any other suitable location.

[0205] As described above with respect to Figures 1, 6, and 7, a heating wire 215 may be included in the inspiratory tube 103 and / or a heating wire 601 may be included in the expiratory tube 117 in order to reduce the risk of condensation formation in the tube by raising the temperature of the gas (mainly the gas near the tube wall) above the saturation temperature. It should be understood that the heating wire may preferably include a coiled or helical configuration and is shown as a straight line for conceptual purposes. The breathing circuit may include a connector (Y connector or Y-piece 801) for connecting the inspiratory tube 103 and the expiratory tube 117 to a patient interface (not shown). It should be understood that, of course, other breathing circuit configurations are also within the scope of this disclosure.

[0206] The foregoing description includes preferred forms of the present invention. Modifications thereto can be made without departing from the scope of the present invention. Those skilled in the art will be able to conceive of many structural modifications of the present invention, as well as a wide range of different embodiments and applications, without departing from the scope of the present invention as defined in the appended claims. The disclosures and descriptions herein are purely illustrative and are not intended to be limiting in any sense.

Claims

1. A circuit kit for use in respiratory therapy for patients, An intake pipe configured to receive an intake gas flow from a gas source, comprising an intake inlet, an intake outlet, and an inner wall surrounding an intake central bore, wherein the inner wall of the intake pipe is smooth, An expiratory tube configured to receive an exhaled gas flow from a patient, comprising an expiratory inlet, an expiratory outlet, and an inner wall surrounding an expiratory center bore, wherein the inner wall of the expiratory tube is wavy, and A circuit kit comprising a breathing circuit including a breathing tube having an inner diameter of 4 to 17 mm, and an exhalation tube having a nominal inner diameter of 10.5 to 20.5 mm.

2. The circuit kit according to claim 1, further comprising a y-piece configured to connect the inhalation tube and the exhalation tube.

3. The circuit kit according to claim 1 or 2, further comprising a chamber for holding a certain amount of water and for placement on a humidifier.

4. The circuit kit according to any one of claims 1 to 3, further comprising a dry line for transporting flow from a ventilator or other gas source to the humidifier inlet.

5. The circuit kit according to any one of claims 1 to 4, wherein the intake pipe has an inner diameter of 6 mm to 10 mm.

6. The circuit kit according to any one of claims 1 to 4, wherein the intake pipe has an inner diameter of 11 mm to 15 mm.

7. The circuit kit according to any one of claims 1 to 4, wherein the intake pipe has an inner diameter of 9 mm to 13 mm.

8. The circuit kit according to any one of claims 1 to 4, wherein the intake pipe has an inner diameter of 10 mm to 14 mm.

9. The circuit kit according to any one of claims 1 to 4, wherein the intake pipe has an inner diameter of 7 mm to 13 mm.

10. The circuit kit according to any one of claims 1 to 4, wherein the intake pipe has an inner diameter of 8 mm to 14 mm.

11. The circuit kit according to any one of claims 1 to 10, wherein the exhalation tube has a nominal inner diameter of 11 mm to 15 mm.

12. The circuit kit according to any one of claims 1 to 10, wherein the exhalation tube has a nominal inner diameter of 12 mm to 16 mm.

13. The circuit kit according to any one of claims 1 to 10, wherein the exhalation tube has a nominal inner diameter of 14 mm to 18 mm.

14. The circuit kit according to any one of claims 1 to 10, wherein the exhalation tube has a nominal inner diameter of 16 mm to 20 mm.

15. The circuit kit according to any one of claims 1 to 10, wherein the exhalation tube has a nominal inner diameter of 13 mm to 19 mm.

16. The circuit kit according to any one of claims 1 to 10, wherein the exhalation tube has a nominal inner diameter of 14 mm to 20 mm.

17. The circuit kit according to any one of claims 1 to 16, wherein the inhalation tube or the exhalation tube has a length of 1.5 m to 2.5 m.

18. The circuit kit according to any one of claims 1 to 16, wherein the inhalation tube or the exhalation tube has a length of 1.6 m to 2.5 m.

19. The circuit kit according to any one of claims 1 to 18, wherein the intake pipe surrounds a heating element within the intake center bore or within the inner wall.

20. The circuit kit according to any one of claims 1 to 19, wherein the exhalation tube includes a heating element.

21. The circuit kit according to any one of claims 1 to 20, wherein the exhalation tube is breathable.

22. The circuit kit according to any one of claims 1 to 21, wherein the inner wall of the exhalation tube is permeable to water vapor and substantially impermeable to the bulk flow of liquid and exhaled gas flowing through the exhalation tube.

23. The circuit kit according to any one of claims 1 to 22, wherein the intake pipe includes a plurality of bubbles, each having a flat surface that forms at least a portion of the wall of the intake center bore in a longitudinal cross-section.

24. The circuit kit according to claim 1, suitable for treating patients with a tidal volume in the range of 50 ml to 300 ml.

25. The circuit kit according to claim 1, which is suitable for the treatment of pediatric and adolescent patients.

26. The circuit kit according to any one of claims 1 to 25, wherein the difference between the inner diameter of the inhalation tube and the nominal diameter of the exhalation tube is 1 mm to 14 mm.

27. The circuit kit according to any one of claims 1 to 25, wherein the inner diameter of the inhalation tube is 1 mm to 14 mm smaller than the nominal diameter of the exhalation tube.

28. The circuit kit according to any one of claims 1 to 27, wherein the intake tube and / or the exhalation tube may include a plurality of sections for housing other equipment such as a water trap and / or an intermediate connector having one or more sensors and / or a PCB and / or a controller.

29. A system comprising the circuit kit according to any one of claims 1 to 28, further comprising a humidifier.

30. A circuit kit for use in respiratory therapy for patients, An intake pipe configured to receive an intake gas flow from a gas source, comprising an intake inlet, an intake outlet, and an inner wall surrounding an intake central bore, wherein the inner wall of the intake pipe is smooth, An expiratory tube configured to receive an exhaled gas flow from a patient, comprising an expiratory inlet, an expiratory outlet, and an inner wall surrounding an expiratory center bore, wherein the inner wall of the expiratory tube is wavy, and A circuit kit comprising a breathing circuit including, wherein the inspiratory tube has an inner diameter of 9.5 to 24 mm, and the expiratory tube has a nominal inner diameter of 19 to 31.5 mm.

31. The circuit kit according to claim 30, further comprising a y-piece configured to connect the inhalation tube and the exhalation tube.

32. The circuit kit according to claim 30 or 31, further comprising a chamber for holding a certain amount of water and for placement on a humidifier.

33. The circuit kit according to any one of claims 30 to 32, further comprising a dry line for transporting flow from a ventilator or other gas source to the humidifier inlet.

34. The circuit kit according to any one of claims 30 to 33, wherein the intake pipe has an inner diameter of 11 mm to 15 mm.

35. The circuit kit according to any one of claims 30 to 33, wherein the intake pipe has an inner diameter of 12 mm to 16 mm.

36. The circuit kit according to any one of claims 30 to 33, wherein the intake pipe has an inner diameter of 18 mm to 22 mm.

37. The circuit kit according to any one of claims 30 to 33, wherein the intake pipe has an inner diameter of 19 mm to 23 mm.

38. The circuit kit according to any one of claims 30 to 33, wherein the intake pipe has an inner diameter of 10 mm to 16 mm.

39. The circuit kit according to any one of claims 30 to 33, wherein the intake pipe has an inner diameter of 17 mm to 23 mm.

40. The circuit kit according to any one of claims 30 to 39, wherein the exhalation tube has a nominal inner diameter of 25 mm to 29 mm.

41. The circuit kit according to any one of claims 30 to 39, wherein the exhalation tube has a nominal inner diameter of 26 mm to 30 mm.

42. The circuit kit according to any one of claims 30 to 39, wherein the exhalation tube has a nominal inner diameter of 20 mm to 24 mm.

43. The circuit kit according to any one of claims 30 to 39, wherein the exhalation tube has a nominal inner diameter of 21 mm to 25 mm.

44. The circuit kit according to any one of claims 30 to 39, wherein the exhalation tube has a nominal inner diameter of 24 mm to 30 mm.

45. The circuit kit according to any one of claims 30 to 39, wherein the exhalation tube has a nominal inner diameter of 20 mm to 26 mm.

46. The circuit kit according to any one of claims 30 to 45, wherein the inhalation tube or the exhalation tube has a length of 1.5 m to 2.5 m.

47. The circuit kit according to any one of claims 30 to 45, wherein the inhalation tube or the exhalation tube has a length of 1.6 m to 2.5 m.

48. The circuit kit according to any one of claims 30 to 47, wherein the intake pipe surrounds a heating element within the intake center bore or within the inner wall.

49. The circuit kit according to any one of claims 30 to 48, wherein the exhalation tube includes a heating element.

50. The circuit kit according to any one of claims 30 to 49, wherein the exhalation tube is breathable.

51. The circuit kit according to any one of claims 30 to 50, wherein the inner wall of the exhalation tube is permeable to water vapor and substantially impermeable to the bulk flow of liquid and exhaled gas flowing through the exhalation tube.

52. The circuit kit according to any one of claims 30 to 51, wherein the intake pipe includes a plurality of bubbles, each having a flat surface that forms at least a portion of the wall of the intake center bore in a longitudinal cross-section.

53. The circuit kit according to claim 30, suitable for treating patients with a tidal volume exceeding 300 ml.

54. The circuit kit according to claim 30, suitable for the treatment of adult patients.

55. The circuit kit according to any one of claims 30 to 54, wherein the inner diameter of the inhalation tube is 1 mm to 20 mm smaller than the nominal diameter of the exhalation tube.

56. The circuit kit according to any one of claims 30 to 54, wherein the inhalation tube is 1 mm to 20 mm smaller than the exhalation tube.

57. The circuit kit according to any one of claims 30 to 56, wherein the intake tube and / or the exhalation tube may include a plurality of sections for housing other equipment such as a water trap and / or an intermediate connector having one or more sensors and / or a PCB and / or a controller.

58. A system comprising a circuit kit according to any one of claims 30 to 57, further comprising a humidifier.

59. A circuit kit for use in respiratory therapy for patients, An intake pipe configured to receive an intake gas flow from a gas source, comprising an intake inlet, an intake outlet, and an inner wall surrounding an intake central bore, wherein the inner wall of the intake pipe is smooth, An expiratory tube configured to receive an exhaled gas flow from a patient, comprising an expiratory inlet, an expiratory outlet, and an inner wall surrounding an expiratory center bore, wherein the inner wall of the expiratory tube is wavy, and A circuit kit comprising a breathing circuit including a breathing tube having an inner diameter of 3 to 13 mm, and an exhalation tube having a nominal inner diameter of 9.5 to 19 mm.

60. The circuit kit according to claim 59, further comprising a y-piece configured to connect the inhalation tube and the exhalation tube.

61. The circuit kit according to claim 59 or 60, further comprising a chamber for holding a certain amount of water and for placement on a humidifier.

62. The circuit kit according to any one of claims 59 to 61, further comprising a dry line for transporting flow from a ventilator or other gas source to the humidifier inlet.

63. The circuit kit according to any one of claims 59 to 62, wherein the intake pipe has an inner diameter of 5 mm to 9 mm.

64. The circuit kit according to any one of claims 59 to 62, wherein the intake pipe has an inner diameter of 6 mm to 10 mm.

65. The circuit kit according to any one of claims 59 to 62, wherein the intake pipe has an inner diameter of 7 mm to 11 mm.

66. The circuit kit according to any one of claims 59 to 62, wherein the intake pipe has an inner diameter of 8 mm to 12 mm.

67. The circuit kit according to any one of claims 59 to 62, wherein the intake pipe has an inner diameter of 4 mm to 11 mm.

68. The circuit kit according to any one of claims 59 to 62, wherein the intake pipe has an inner diameter of 6 mm to 12 mm.

69. The circuit kit according to any one of claims 59 to 68, wherein the exhalation tube has a nominal inner diameter of 13 mm to 17 mm.

70. The circuit kit according to any one of claims 59 to 68, wherein the exhalation tube has a nominal inner diameter of 12 mm to 16 mm.

71. The circuit kit according to any one of claims 59 to 68, wherein the exhalation tube has a nominal inner diameter of 11 mm to 15 mm.

72. The circuit kit according to any one of claims 59 to 68, wherein the exhalation tube has a nominal inner diameter of 14 mm to 18 mm.

73. The circuit kit according to any one of claims 59 to 68, wherein the exhalation tube has a nominal inner diameter of 12 mm to 18 mm.

74. The circuit kit according to any one of claims 59 to 68, wherein the exhalation tube has a nominal inner diameter of 10 mm to 16 mm.

75. The circuit kit according to any one of claims 59 to 74, wherein the inhalation tube or the exhalation tube has a length of 1.5 m to 2.5 m.

76. The circuit kit according to any one of claims 59 to 74, wherein the inhalation tube or the exhalation tube has a length of 1.6 m to 2.5 m.

77. The circuit kit according to any one of claims 59 to 76, wherein the intake pipe surrounds a heating element within the intake center bore or within the wall of the pipe.

78. The circuit kit according to any one of claims 59 to 77, wherein the exhalation tube includes a heating element.

79. The circuit kit according to any one of claims 59 to 78, wherein the exhalation tube is breathable.

80. The circuit kit according to any one of claims 59 to 79, wherein the inner wall of the exhalation tube is permeable to water vapor and substantially impermeable to the bulk flow of liquid and exhaled gas flowing through the exhalation tube.

81. The circuit kit according to any one of claims 59 to 80, wherein the intake pipe includes a plurality of bubbles, each having a flat surface that forms at least a portion of the wall of the intake center bore in a longitudinal cross-section.

82. The circuit kit according to claim 59, suitable for treating patients with a tidal volume of 50 ml or less.

83. The circuit kit according to claim 59, suitable for the treatment of neonatal patients.

84. The circuit kit according to any one of claims 59 to 83, wherein the difference between the inner diameter of the inhalation tube and the nominal diameter of the exhalation tube is 1 mm to 14 mm.

85. The circuit kit according to any one of claims 59 to 83, wherein the inner diameter of the inhalation tube is smaller by 1 mm to 14 mm than the nominal diameter of the exhalation tube.

86. A system comprising a circuit kit according to any one of claims 59 to 85, further comprising a humidifier.

87. A circuit kit for use in respiratory therapy for patients, An intake pipe configured to receive an intake gas flow from a gas source, comprising an intake inlet, an intake outlet, and an inner wall surrounding an intake central bore, wherein the inner wall of the intake pipe is smooth, An expiratory tube configured to receive an exhaled gas flow from a patient, comprising an expiratory inlet, an expiratory outlet, and an inner wall surrounding an expiratory center bore, wherein the inner wall of the expiratory tube is wavy, and A circuit kit comprising a breathing circuit including a breathing tube having an inner diameter of 3 mm to 11 mm, and an exhalation tube having a nominal inner diameter of 8 mm to 16 mm.

88. The circuit kit according to claim 87, wherein the intake pipe has an inner diameter of 4 mm to 8 mm.

89. The circuit kit according to claim 88, wherein the exhalation tube has a nominal inner diameter of 11 mm to 15 mm.

90. The circuit kit according to claim 87, wherein the intake pipe has an inner diameter of 6 mm to 10 mm.

91. The circuit kit according to claim 90, wherein the exhalation tube has a nominal inner diameter of 10 mm to 14 mm.

92. The circuit kit according to any one of claims 87 to 91, wherein the inhalation tube or the exhalation tube has a length of 1.5 m to 2.5 m.

93. A circuit kit for use in respiratory therapy for patients, An intake pipe configured to receive an intake gas flow from a gas source, comprising an intake inlet, an intake outlet, and an inner wall surrounding an intake central bore, wherein the inner wall of the intake pipe is smooth, An expiratory tube configured to receive an exhaled gas flow from a patient, comprising an expiratory inlet, an expiratory outlet, and an inner wall surrounding an expiratory center bore, wherein the inner wall of the expiratory tube is wavy, and A circuit kit comprising a breathing circuit including a breathing tube having an inner diameter of 5 mm to 13 mm, and an exhalation tube having a nominal inner diameter of 15 mm to 23 mm.

94. The circuit kit according to claim 93, wherein the intake pipe has an inner diameter of 5 mm to 9 mm.

95. The circuit kit according to claim 94, wherein the exhalation tube has a nominal inner diameter of 18 mm to 22 mm.

96. The circuit kit according to claim 93, wherein the intake pipe has an inner diameter of 8 mm to 12 mm.

97. The circuit kit according to claim 96, wherein the exhalation tube has a nominal inner diameter of 16 mm to 20 mm.

98. The circuit kit according to any one of claims 93 to 97, wherein the inhalation tube or the exhalation tube has a length of 1.5 m to 2.5 m.

99. A circuit kit for use in respiratory therapy for patients, An intake pipe configured to receive an intake gas flow from a gas source, comprising an intake inlet, an intake outlet, and an inner wall surrounding an intake central bore, wherein the inner wall of the intake pipe is smooth, An expiratory tube configured to receive an exhaled gas flow from a patient, comprising an expiratory inlet, an expiratory outlet, and an inner wall surrounding an expiratory center bore, wherein the inner wall of the expiratory tube is wavy, and A circuit kit comprising a breathing circuit including a breathing tube having an inner diameter of 10 mm to 18 mm, and an exhalation tube having a nominal inner diameter of 24 mm to 32 mm.

100. The circuit kit according to claim 99, wherein the intake pipe has an inner diameter of 9 mm to 13 mm.

101. The circuit kit according to claim 100, wherein the exhalation tube has a nominal inner diameter of 27 mm to 31 mm.

102. The circuit kit according to claim 99, wherein the intake pipe has an inner diameter of 15 mm to 19 mm.

103. The circuit kit according to claim 102, wherein the exhalation tube has a nominal inner diameter of 24 mm to 28 mm.

104. The circuit kit according to any one of claims 99 to 103, wherein the inhalation tube or the exhalation tube has a length of 1.5 m to 2.5 m.

105. A circuit kit for use in respiratory therapy for patients, An intake pipe configured to receive an intake gas flow from a gas source, comprising an intake inlet, an intake outlet, and an inner wall surrounding an intake central bore, wherein the inner wall of the intake pipe is smooth, An expiratory tube configured to receive an exhaled gas flow from a patient, comprising an expiratory inlet, an expiratory outlet, and an inner wall surrounding an expiratory center bore, wherein the inner wall of the expiratory tube is wavy, and A circuit kit comprising a breathing circuit including the inspiratory tube having an inner diameter and length, and the expiratory tube having a nominal inner diameter and length, the circuit kit being suitable for the treatment of adult patients.

106. A circuit kit for use in respiratory therapy for patients, An intake pipe configured to receive an intake gas flow from a gas source, comprising an intake inlet, an intake outlet, and an inner wall surrounding an intake central bore, wherein the inner wall of the intake pipe is smooth, An expiratory tube configured to receive an exhaled gas flow from a patient, comprising an expiratory inlet, an expiratory outlet, and an inner wall surrounding an expiratory center bore, wherein the inner wall of the expiratory tube is wavy, and A circuit kit comprising a breathing circuit including the inspiratory tube having an inner diameter and length, and the expiratory tube having a nominal inner diameter and length, the circuit kit being suitable for the treatment of pediatric and adolescent patients.

107. A circuit kit for use in respiratory therapy for patients, An intake pipe configured to receive an intake gas flow from a gas source, comprising an intake inlet, an intake outlet, and an inner wall surrounding an intake central bore, wherein the inner wall of the intake pipe is smooth, An expiratory tube configured to receive an exhaled gas flow from a patient, comprising an expiratory inlet, an expiratory outlet, and an inner wall surrounding an expiratory center bore, wherein the inner wall of the expiratory tube is wavy, and A circuit kit comprising a breathing circuit including the inspiratory tube having an inner diameter and length, and the expiratory tube having a nominal inner diameter and length, the circuit kit being suitable for the treatment of pediatric and neonatal patients.

108. A circuit kit for use in respiratory therapy for patients, An intake pipe configured to receive an intake gas flow from a gas source, comprising an intake inlet, an intake outlet, and an inner wall surrounding an intake central bore, wherein the inner wall of the intake pipe is smooth, An expiratory tube configured to receive an exhaled gas flow from a patient, comprising an expiratory inlet, an expiratory outlet, and an inner wall surrounding an expiratory center bore, wherein the inner wall of the expiratory tube is wavy, and A circuit kit comprising a breathing circuit including a breathing tube having an inner diameter of approximately 11.7 mm and an exhalation tube having a nominal inner diameter of approximately 14.5 mm.

109. The circuit kit according to claim 108, wherein the inhalation tube and / or the exhalation tube has a length of approximately 1.75 m.

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