Flexible hybrid medical tubing for newborns

Abstract

The present invention provides medical tubing for use in positive airway pressure (PAP), respirators, anesthesia, ventilators, and air delivery systems, and methods for manufacturing medical tubing. [Solution] The tube may be a composite structure made up of two or more separate components helically wound to form an elongated tube. One of the components may be a helically wound elongated hollow body, and the other component may be an elongated structural component helically wound between the turns of the helically wound hollow body. Alternatively, the tube need not be formed from separate components. An elongated hollow body formed (e.g., extruded) from a single material may be helically wound to form the elongated tube. The elongated hollow body itself may have a thin-walled portion and a relatively thicker or more rigid reinforcement portion in transverse cross-section. The tube may be incorporated into various medical circuits or used for other medical applications.

Description

Technical Field

[0001] Incorporation by reference The entire contents of the following patent applications are hereby incorporated by reference and made a part of this specification: U.S. Patent Application Publication No. 14 / 351,344, entitled "MEDICAL TUBES AND METHODS OF MANUFACTURE", filed on April 11, 2014; U.S. Patent Application Publication No. 14 / 649,801, entitled "MEDICAL TUBES AND METHODS OF MANUFACTURE", filed on June 4, 2015; and PCT Application PCT / NZ2013 / 000208, entitled "ZONE HEATING FOR RESPIRATORY CIRCUITS", filed on November 14, 2013.

[0002] The present disclosure generally relates to tubes suitable for medical applications, and more particularly to tubes for use in medical circuits suitable for providing gas to and / or removing gas from a patient.

Background Art

[0003] In medical circuits, various components exchange heated and / or humidified gas with the patient. For example, in some breathing circuits, such as PAP and assisted breathing circuits, the gas inhaled by the patient is delivered from a heater / humidifier through an inhalation tube. As another example, a tube can deliver humidified gas (usually CO2) to the abdominal cavity within the supply circuit. This can help prevent "drying out" of the patient's internal organs and reduce the amount of time required for recovery from surgery. Unheated tubing results in significant heat loss to ambient cooling. This cooling can lead to undesirable condensation or "rainout" along the length of the tubing transporting heated and humidified air. Furthermore, users require flexible, lightweight tubing to improve ease of positioning and use when providing respiratory therapy to patients, especially neonatal patients. However, when creating lightweight, flexible tubing, the tubing can undergo significant movement and displacement when specific respiratory waveforms are transmitted through the breathing tube. [Overview of the Initiative] [Means for solving the problem]

[0004] This specification discloses medical tubing in various embodiments, such as positive airway pressure (PAP), ventilators, anesthesia, ventilators, and air supply systems, as well as methods for manufacturing medical tubing. In some embodiments, the tubing may be a composite structure composed of two or more distinct components that are spirally wound to form an elongated tube. For example, one component may be a spirally wound elongated hollow body, and the other components may be elongated structural components that are also spirally wound between the spirally wound hollow body. In other embodiments, the tubing does not need to be formed from different components. For example, an elongated hollow body formed from a single material (e.g., extruded) may be spirally wound to form an elongated tube. The elongated hollow body itself may have, in a transverse cross-section, thin wall portions and relatively thicker or more rigid reinforcing portions. The tubing can be incorporated into various medical circuits or used for other medical applications.

[0005] Several embodiments provide a breathing tube. The breathing tube may include a first segment and a second segment. The first segment may have a first flexibility, and the second segment may have a second flexibility. The second flexibility may be different from the first flexibility. In certain embodiments, the breathing tube may include an intermediate connector connecting the first segment to the second segment. In certain embodiments, the breathing tube may include a substantially inflexible segment connecting the first segment to the second segment.

[0006] In some embodiments, the breathing tube may include a sheath around at least one of the first or second segments. The sheath may extend to at least a partial length of at least one segment. In certain embodiments, the sheath may extend substantially along the entire length of at least one segment. The sheath may be configured to maintain flexibility and dampen displacement while gas flows through the breathing tube. In some embodiments, the sheath may be a mesh sheath, a braided sheath, or a walled sheath. An intermediate connector may secure at least one end of the sheath. In certain embodiments, the intermediate connector may electrically and pneumatically connect the first and second segments. The sheath may cover the intermediate connector.

[0007] In some embodiments, the segment closer to the patient is more flexible. The first and second segments of the breathing tube may be a composite tube. The composite tube may have a first elongated member and a second elongated member. The first elongated member may include a hollow body wound spirally to form at least a portion of the breathing tube, and the second elongated member may be joined by being wound spirally between adjacent windings of the first elongated member. The second elongated member may form at least a portion of the lumen of the breathing tube.

[0008] In certain embodiments, the cross-sectional width and height of the first elongated member of the more flexible segment are narrower and taller, respectively, than those of the first elongated member of the less flexible segment. The more flexible segment can have various modifications that can provide greater flexibility compared to the more stiff segment. Some exemplary modifications may include one or more of a smaller inner diameter, a smaller pitch, a smaller width of the second elongated member, or thinner sidewalls. The sidewalls in the lumen of the more flexible segment are thinner than those of the more rigid segment. In certain embodiments, the sidewalls adjacent to the gas lumen of the first elongated member of the more flexible segment are thinner than the sidewalls adjacent to the gas lumen of the first elongated member of the less flexible segment.

[0009] In some embodiments, the breathing tube is an inspiratory tube within a breathing circuit. The breathing tube can be sized for use in neonates. The breathing tube may include a humidifier end adapted for connection to a humidifier. The breathing tube may include a patient end adapted for connection to a patient interface or Y-shaped piece.

[0010] Another embodiment provides a breathing tube comprising a first segment having first flexibility and a sheath. The sheath can cover the first segment. The sheath can be configured to maintain flexibility and dampen displacement while gas flows through the breathing tube. In certain embodiments, the breathing tube may include a second segment having second flexibility and an intermediate connector. The intermediate connector can connect the first segment to the second segment. In certain embodiments, the flexibility of the second segment may be the same as that of the first segment. In other embodiments, the flexibility of the second segment may be different from that of the first segment.

[0011] In certain embodiments, the intermediate connector can secure at least one end of the sheath. The sheath may be around at least one of the first segment or the second segment. The sheath may extend over at least a partial length of the first and / or second segment. In certain embodiments, the sheath is around at least one of the first or second segment and extends substantially along the entire length of the first and / or second segment. The sheath may extend at least partially over the respective lengths of the first and second segments.

[0012] In some embodiments, the first and second segments of the breathing tube may be a composite tube. The composite tube may have a first elongated member and a second elongated member. The first elongated member may include a hollow body wound helically to form at least a portion of the breathing tube, and the second elongated member may be wound helically between adjacent windings of the first elongated member and joined. The second elongated member may form at least a portion of the lumen of the breathing tube. In certain embodiments, the cross-sectional width and height of the first elongated member of a higher-flexibility segment are narrower and taller, respectively, than the cross-sectional width and height of the first elongated member of a lower-flexibility segment. The higher-flexibility segment may have various modifications that can provide greater flexibility compared to a higher-stiffness segment. Some exemplary modifications may include one or more of a smaller inner diameter, a smaller pitch, a smaller width of the second elongated member, or thinner sidewalls. The side walls in the lumen of a segment with higher flexibility may be thinner than those of a segment with higher rigidity. In certain embodiments, the side wall adjacent to the gas lumen of a first elongated member of a segment with higher flexibility is thinner than the side wall adjacent to the gas lumen of a first elongated member of a segment with lower flexibility.

[0013] Another embodiment provides a breathing tube comprising a humidifier end segment having a first degree of flexibility and a patient interface end segment having a second degree of flexibility. The second degree of flexibility of the patient interface end segment is the same as the first degree of flexibility of the humidifier end segment. A sheath can cover the humidifier end segment. The sheath is configured to maintain flexibility and dampen displacement in the gas flow. In some embodiments, the breathing tube may further include an intermediate connector connecting the humidifier end segment to the patient interface end segment. The intermediate connector secures at least one end of the sheath. The sheath may extend over at least a portion of the length of the humidifier end segment. In certain embodiments, the sheath may extend substantially along the entire length of the humidifier end segment. In some embodiments, the sheath is around both the humidifier end segment and the patient interface end segment. The sheath may extend over at least a portion of the length of each segment.

[0014] In some embodiments, the humidifier end segment and the patient interface end segment of the breathing tube may be a composite tube. The composite tube may have a first elongated member and a second elongated member. The first elongated member may include a hollow body that is spirally wound to form at least a portion of the breathing tube, and the second elongated member may be spirally wound and joined between adjacent windings of the first elongated member. The second elongated member may form at least a portion of the lumen of the breathing tube.

[0015] Some embodiments provide circuit kits for humidified medical gases. The circuit kit may include a humidification chamber and an inspiratory limb. The inspiratory limb may include a first segment of a breathing tube having first flexibility and a second segment of a breathing tube having second flexibility, wherein the second flexibility is different from the first flexibility.

[0016] In some embodiments, the circuit kit may include a Y-shaped piece. The circuit kit may include an expiratory limb. The circuit kit may include a patient interface. The circuit kit may include an intermediate connector connecting a first segment to a second segment. The circuit kit may include a sheath around at least one of the first segment or the second segment. The circuit kit may include a dryline.

[0017] Some embodiments provide a breathing tube. The breathing tube may include a first segment of a breathing tube having first flexibility, a second segment of a breathing tube having second flexibility, and a segment connector adapted to connect the first segment to the second segment. The segment connector may include a connection circuit configured to selectively provide power delivered to the conductive filament of the first segment to the conductive filament of the second segment.

[0018] In some embodiments, the connection circuit may include a diode. The diode can prevent power of a first polarity delivered to the conductive filament of the first segment from being delivered to the conductive filament of the second segment. The diode may allow power of a second polarity delivered to the conductive filament of the first segment to be delivered to the conductive filament of the second segment.

[0019] In some embodiments, the connection circuit may be configured to power the conductive filament of the first segment without powering the conductive filament of the second segment in a first mode, and the connection circuit may be configured to power both the conductive filament of the first segment and the conductive filament of the second segment in a second mode.

[0020] In some embodiments of the breathing tube, the second flexibility is the same as the first flexibility. In some embodiments of the breathing tube, the second flexibility is different from the first flexibility. In some embodiments, the breathing tube may include a sheath around at least one of the first segment or the second segment. An intermediate connector can secure at least one end of the sheath.

[0021] In some embodiments, control of the conductive filament and reading of the sensor can be achieved using fewer than four wires in each segment (e.g., using three wires or two wires) or more than four wires in each segment (e.g., using five wires, six wires, seven wires, eight wires, or nine or more wires).

[0022] For the purpose of summarizing the present invention, specific aspects, advantages, and novel features of the present invention are described herein. It should be understood that not all such advantages are necessarily achieved according to any particular embodiment of the present invention. Accordingly, the present invention may be embodied or practiced to achieve or optimize one or a group of advantages taught herein, without necessarily achieving other advantages that may be taught or suggested herein.

[0023] Next, exemplary embodiments that implement various features of the disclosed systems and methods are described with reference to the drawings. The drawings and related descriptions are provided to illustrate the embodiments and are not intended to limit the scope of this disclosure. [Brief explanation of the drawing]

[0024] [Figure 1] A diagram illustrating an exemplary respiratory humidification system for supplying humidifying gas to a user, wherein the respiratory humidification system has a breathing circuit, and the breathing circuit includes segmented inspiratory limbs having sensors in each segment. [Figure 2A]A diagram showing a segmented intake limb for use with a humidification system, the segmented intake limb having an intermediate connector configured to couple heater wires and sensors within two segments. [Figure 2B] A diagram showing an exemplary embodiment of a humidification system that utilizes a microcontroller in an intermediate connector to measure data for controlling heating and read sensor values in the intake limb. [Figure 2C] A block diagram of an exemplary intermediate connector for an intake limb, showing the intermediate connector using a microcontroller. [Figure 2D] A circuit diagram of an exemplary power module and data line converter included in the intermediate connector shown in Figure 2C. [Figure 2E] A circuit diagram of an exemplary dual optocoupler circuit used with the intermediate connector shown in Figure 2C to provide bidirectional data communication between the control side and the AC side on a power board. [Figure 2F-2G] A diagram showing an exemplary printed circuit board ("PCB") of an intermediate connector. [Figure 2H-2I] A diagram showing an exemplary embodiment of an intermediate connector. [Figure 2J-2K] An exemplary circuit diagram including an active rectifier power supply for providing power to heater wires within a segmented intake limb of a breathing circuit, the circuit being configured to supply power to heater wires in a first segment of the intake limb in a first mode and to heater wires in both segments in a second mode. [Figure 2L-2M] An exemplary circuit diagram within a humidification system, the circuit being configured to read data from two sensors. [Figure 3A] A side view of a section of an exemplary composite tube. [Figure 3B] A longitudinal cross-sectional view of the upper part of a tube similar to the exemplary composite tube of Figure 3A. [Figure 3C] Another longitudinal cross-sectional view showing a first elongated member within the composite tube. [Figure 3D] This is another longitudinal cross-section of the top of the pipe. [Figure 3E] This is another longitudinal cross-section of the top of the pipe. [Figure 4A-4C] This figure shows an example of the shape of a first elongated member configured to improve thermal efficiency. [Figure 4D-4F] This figure shows an example of a filament configuration designed to improve thermal efficiency. [Figures 5A-5E] This figure shows examples of the shapes of a first elongated member and a second elongated member configured to improve flexibility. [Figure 6A-6C] This is an exemplary longitudinal cross-sectional view of a composite tube. [Figures 7A-7B] This figure shows an example of a breathing tube having a first section and a second section with different flexibility. [Figures 8A-8E] This figure shows an example of a breathing tube having a first section and a second section, each equipped with a mesh in one or more sections of the breathing tube. [Modes for carrying out the invention]

[0025] Generally, reference numbers are reused throughout the drawing to indicate correspondences between referenced (or similar) elements. Nevertheless, in some situations, corresponding referenced (or similar) elements may have different reference numbers.

[0026] Details of several exemplary embodiments for carrying out the apparatus and methods described herein are described below with reference to the drawings. The present invention is not limited to these described embodiments.

[0027] This specification describes specific embodiments and examples of segmented intake limbs and multi-zone heating. Those skilled in the art will understand that this disclosure also includes the specifically disclosed embodiments and / or uses, as well as obvious modifications and equivalents thereof. Accordingly, the scope of this disclosure as disclosed herein is not intended to be limited by any specific embodiment described herein.

[0028] This specification describes systems and methods for providing heat to segmented inspiratory limbs within a respiratory circuit of a respiratory humidification system. While most of the descriptions herein are in the context of segmented inspiratory limbs within a respiratory circuit, it should be understood that one or more features of this disclosure may also be implemented in other scenarios where it is desirable to provide differentiated heating in segmented gas delivery lines, for example, in respiration, surgery, or other applications.

[0029] This disclosure refers to heater wires, heating elements, heating filaments and / or heaters in the context of providing heat to conduits. For example, heater wire is a broad term and should be interpreted in its ordinary and customary sense to those skilled in the art (i.e., not limited to any particular or specialized sense), and includes, but is not limited to, heater strips, heating filaments and / or heat transfer elements that generate heat when power is supplied. Examples of such heating elements include wires formed from conductive metals (e.g., copper), conductive polymers, conductive inks printed on the surface of conduits, conductive materials used to create tracks in conduits, etc. Furthermore, this disclosure refers to conduits, limbs and medical tubes in the context of gas delivery. For example, tube is a broad term and should be interpreted in its ordinary and customary sense to those skilled in the art, and includes, but is not limited to, paths having various cross-sections, such as cylindrical and non-cylindrical paths. Certain embodiments may incorporate composite tubing, which can generally be defined as a tube comprising two or more parts, or in some embodiments, two or more components, as described in more detail below. Segmented limbs comprising the disclosed medical tubing can also be used in breathing circuits such as continuous, variable, or two-level positive airway pressure (PAP) systems, high-flow delivery, invasive ventilation, non-invasive ventilation, high-flow during anesthesia or sedation, or other respiratory therapies. The terms “tubing” and “limbs” should be interpreted as being synonymous with “tubing.”

[0030] When a heated and humidified breathing tube is used for an incubator (or any area with temperature variations, such as around a radiant heater used for burn patients or under a blanket used by a patient), the breathing tube passes through at least two different regions: a low-temperature region (such as a region outside the incubator) and a high-temperature region (such as a region inside the incubator). If the tube is heated along its entire length, depending on which region is sensed (e.g., which region contains the temperature sensor), one of the regions tends to reach an undesirable, inappropriate, or suboptimal temperature. If the heater wire is controlled by a sensor inside the incubator (such as a patient-end temperature sensor), the section outside the incubator tends to become too low in temperature, which can lead to condensation. Conversely, if the heater wire is controlled by a sensor outside the incubator, the section inside the incubator may become too high in temperature, which can result in the patient receiving gas that is too hot. Therefore, this disclosure describes systems and methods that enable heat control within a segmented breathing tube. Here, each segment has associated sensors that provide feedback to a control module. While several embodiments are described herein with respect to two zones, such systems can also be extended to accommodate applications using further zones, segments, or regions. For example, in one embodiment having three temperature zones, a segment of the breathing tube may be heated based on at least part of three different temperature sensors within the zone. Furthermore, embodiments disclosed herein can control the heat supplied to the breathing tube based on parameters at the patient end, by bypassing or ignoring one or more sensors located at midpoints along the tube. Moreover, embodiments disclosed herein can control the heat supplied to the breathing tube using parameters provided by sensors, including, but not limited to, temperature sensors, humidity sensors, flow sensors, and oxygen sensors.

[0031] The control module can monitor and control the heating temperature in multiple areas or sections. The control module can be configured to provide heat to a first section of the breathing tube in a first mode and to provide heat to the entire breathing tube in a second mode, using several embodiments of the connector assemblies described herein. Several embodiments described herein can be used without flying leads, exposed connectors, and / or electrical connection wires at the patient end. The term “flying lead” as used herein includes electrical connection wires extending outside the breathing tube, electrical connection wires extending inward through the breathing tube, and electrical connection wires incorporated, molded, or otherwise formed or embedded as part of the breathing tube. The control module can be located inside or outside the humidifier. In some embodiments, the control unit is located inside the humidifier and controls heater wires associated with a first segment of the inspiratory limb, a second segment of the inspiratory limb, and the expiratory limb, and also reads parameters from sensors associated with the first and second segments of the inspiratory limb and / or the expiratory limb.

[0032] The control module can also adaptively change the temperature related to a segment. For example, the control module can monitor temperature sensors associated with one or more segments. Monitoring may be continuous, periodic, interrupt-based, or event-based. For example, monitoring of temperature sensors may be based on reading values ​​from analog / digital converters, determining voltage or current, sensing logical conditions, reading thermostat devices, measuring thermistor values, measuring resistance temperature detectors, measuring the voltage of thermocouples, or other methods for sensing temperature, such as, but not limited to, semiconductor junction sensors, infrared or thermal radiation sensors, thermometers, indicators, etc. In some embodiments, the temperature sensor is a thermistor. Monitoring may be based on a power signal, for example, the measurement frequency of the sensor may be synchronous or asynchronous with the power signal frequency.

[0033] In some embodiments, the ratio of power delivered to a first segment of the inspiratory limb and a second segment of the inspiratory limb can be changed in use, at least in part, based on feedback from sensors associated with each segment. For example, the power ratio can be changed so that each segment is heated to a temperature that reduces or prevents condensation. As a further example, the power ratio can be changed so that gas that is too hot is not delivered to the patient. In some embodiments, the power ratio can be continuously changed based on feedback from sensors (e.g., temperature sensors, humidity sensors, oxygen sensors, flow sensors, optical sensors, etc.). The power ratio can be changed in a variety of ways. For example, the power ratio can be changed by changing the amplitude of the power signal (including, but not limited to, voltage and / or current), the duration of the power signal, or the duty cycle of the power signal, or by other appropriate modifications to the power signal. In one embodiment, the power ratio is changed by changing the magnitude of the current being delivered.

[0034] Respiratory humidification system Figure 1 shows an exemplary respiratory humidification system 100 for delivering humidified gas to a user, the respiratory humidification system 100 having a breathing circuit 200, the breathing circuit 200 including a segmented inspiratory limb 202 having a sensor 204b on one segment, and the inspiratory limb 202 may optionally include a sensor 204a on another segment. The segmented inspiratory limb 202 can be used with an incubator 208 as shown, or with another system, such as a radiant heater, where different temperatures exist along the various segments of the inspiratory limb 202. The segmented inspiratory limb 202 can be used to provide different levels of heat to the various segments 202a, 202b of the inspiratory limb, to reduce or prevent condensation, and / or control the temperature of the gas delivered to the user. In some embodiments, the inspiratory limb 202 is not segmented.

[0035] The illustrated respiratory humidification system 100 includes a pressurized gas source 102. In some implementations, the pressurized gas source 102 includes a fan or blower, etc. In some implementations, the pressurized gas source 102 includes a ventilation device or other positive pressure generating device. The pressurized gas source 102 includes an inlet 104 and an outlet 106. In some embodiments, the pressurized gas source 102 may be a wall gas source. In such embodiments, the gas from the wall may pass through a flow control valve, such as a flow meter or blender or proportional valve, which can be used to control the flow rate delivered to the patient.

[0036] The pressurized gas source 102 provides a flow of fluid (e.g., oxygen, anesthetic gas, air, etc., and / or mixtures of these fluids) to the humidification unit 108. The fluid flow proceeds from the outlet 106 of the pressurized gas source 102 to the inlet 110 of the humidification unit 108. In the illustrated configuration, the humidification unit 108 is shown independently of the pressurized gas source 102, and the inlet 110 of the humidification unit 108 is connected to the outlet 106 of the pressurized gas source 102 by a conduit 112 (often referred to as a "dryline"). In some implementations, the pressurized gas source 102 and the humidification unit 108 can be integrated into a single housing.

[0037] While other types of humidification units may be used to obtain the specific features, embodiments, and advantages described herein, the illustrated humidification unit 108 is a pass-over humidifier comprising a humidification chamber 114 and an inlet 110 to the humidification chamber 114. In some implementations, the humidification chamber 114 comprises a body 116 to which a base 118 is attached. A compartment can be defined within the humidification chamber 116, and the compartment is adapted to hold a volume of liquid that can be heated by heat transmitted or supplied through the base 118. In some implementations, the base 118 is adapted to contact a heater plate 120. The heater plate 120 can be controlled by a control device 122 or other suitable component, thereby allowing modification and control of the heat transmitted into the liquid.

[0038] The control device 122 of the humidification unit 108 can control the operation of various components of the respiratory humidification system 100. While the illustrated system is shown using a single control device 122, other configurations may use multiple control devices. Multiple control devices may communicate with each other or provide individual functions, thus eliminating the need for communication between them. In some implementations, the control device 122 may comprise a microprocessor, processing unit, or logic circuit with associated memory or storage medium containing software code for a computer program. In such implementations, the control device 122 can control the operation of the respiratory humidification system 100, for example, according to instructions contained in a computer program and also in response to internal or external inputs. The control device 122, or at least one of multiple control devices, may be located with the breathing circuit, mounted to the breathing circuit, or incorporated as part of the breathing circuit.

[0039] The main body 116 of the humidifying chamber 114 includes a port 124 defining the inlet 110 of the humidifying chamber 114 and a port 126 defining the outlet 128. When the liquid contained inside the humidifying chamber 114 is heated, the liquid vapor is mixed with the gas introduced into the humidifying chamber 114 through the inlet port 124. The mixture of gas and vapor exits the humidifying chamber 114 through the outlet port 126.

[0040] The respiratory humidification system 100 includes a breathing circuit 200 comprising an inspiratory limb 202 connected to an outlet 128 defining an outlet port 126 of a humidification unit 108. The inspiratory limb 202 transports a mixture of gas and water vapor exiting the humidification chamber 114 toward the user. The inspiratory limb 202 may include a heating element 206 positioned along the inspiratory limb 202, which is configured to reduce condensation along the inspiratory limb 202, thereby controlling the temperature of the gas reaching the user, maintaining the humidity of the gas, or any combination thereof. The heating element 206 can raise or maintain the temperature of the gas and water vapor mixture transported by the inspiratory limb 202. In some implementations, the heating element 206 may be a wire defining a resistance heater. By raising or maintaining the temperature of the gas and water vapor mixture exiting the humidification chamber 114, condensation of water vapor from the mixture is reduced.

[0041] The respiratory humidification system 100 can optionally be used with the incubator 208. The incubator 208 can be configured to maintain a desired environment for the user, for example, a selected, predetermined, or desired temperature inside the incubator 208. Thus, the internal ambient temperature inside the incubator 208 may differ from the external temperature. Thus, the incubator 208 generates, defines, creates, or maintains different temperature zones along the inspiratory limb 202, where the internal temperature is typically higher than the external temperature. Having at least two different temperature zones along the inspiratory limb 202 can cause problems during gas delivery to the user, such as condensation along the inspiratory limb 202, delivery of gas at too high a temperature, or both.

[0042] The respiratory humidification system 100 may include an exhaling limb 210 having an associated heating element 212. In some embodiments, the exhaling limb 210 and the inspiratory limb 202 can be connected using a suitable attachment (e.g., a Y-piece). In some embodiments, the respiratory humidification system 100 may also be used with a radiant heater, under a blanket, or in other systems or situations that form two or more temperature zones. The systems and methods described herein may be used with such systems and are not limited to implementations that incorporate an incubator.

[0043] In exemplary embodiments where the limb is used with an incubator, the inspiratory limb 202 may be divided into segments 202a and 202b, where the first segment 202a may be part of the inspiratory limb 202 outside the incubator 208, and the second segment 202b (e.g., an incubator extension) may be part of the inspiratory limb 202 inside the incubator 208. In other exemplary embodiments where the limb is not used with an incubator, the tube may be segmented as described above, with both segments under the same or similar ambient conditions, or under different ambient conditions (e.g., a fan or HVAC / AC system blowing air to one segment and not the other). The first segment 202a and the second segment 202b may be of different or the same length. In some embodiments, the second segment 202b may be shorter than the first segment 202a, and in certain implementations, the second segment 202b may be about half the length of the first segment 202a. The first segment 202a may have a length of, for example, at least about 0.5m and / or about 2m or less, at least about 0.7m and / or about 1.8m or less, at least about 0.9m and / or about 1.5m or less, or at least about 1m and / or 1.2m or less. The second segment 202b may have a length of, for example, at least about 0.2m and / or about 1.5m or less, at least about 0.3m and / or about 1m or less, at least about 0.4m and / or about 0.8m or less, or at least about 0.5m and / or about 0.7m or less. In one exemplary embodiment, the total length is greater than 2.5m.

[0044] The intake limb segments 202a and 202b can be coupled to each other to form a single gas supply pipeline. In some embodiments, the first segment 202a may include one or more first heater wires 206a, optionally include one or more first sensors 204a, and may be used without the second segment 202b. The control device 122 can be configured to control the first heater wires 206a and read the first sensors 204a (if present) even if the second segment 202b is not coupled to the first segment 202a. Furthermore, when the second segment 202b is coupled to the first segment 202a, the control device 122 can be configured to control the first and second heater wires 206a and 206b within each segment and to read the first sensors 204a (if present) and the second sensors 204b. In some embodiments, the control device 122 can be configured to control the respective first and second heater wires 206a, 206b and read the respective first sensor 204a (if present) and second sensor 204b when the second segment 202b is attached. Alternatively, when the second segment 202b is not attached, it can be configured to control the first heater wire 206a and read the first sensor 204a (if present), without requiring any modification of the control device 122 or the humidification unit 108. Therefore, the same control device 122 and / or humidification unit 108 can be used regardless of whether the inspiratory limb 202 includes both the first segment 202a and the second segment 202b or only the first segment 202a. For example, the same control device 122 and / or humidification unit 108 can be used, where the inspiratory limb is a single-segment inspiratory limb (i.e., does not have multiple segments) and the sensor 204b is on the patient side. In some embodiments, the control device 122 can be further configured to control the heater wire 212 in the exhalation limb 210 without modifying the control device 122 or the humidification unit 108.Therefore, the respiratory humidification system 100 can operate with or without the second segment 202b attached, and / or with or without the expiratory limb 210 attached. In one exemplary embodiment, the expiratory limb control function is a slave control device to the inspiratory limb heater wire control device. Alternatively, the expiratory limb heater wire can be controlled independently of the inspiratory limb heater wire.

[0045] In some embodiments, the first segment 202a and the second segment 202b are permanently joined to each other to form a single gas supply pipeline. As used herein, “permanently joined” means that the segments 202a and 202b are joined to each other by means of, for example, adhesive, friction fit, overmolding, mechanical connectors, etc., in such a way that it is difficult to separate the segments. In some embodiments, the first segment 202a and the second segment 202b are configured to be releasably joined. For example, the first segment 202a can be used for gas supply without the second segment 202b, or the first segment 202a and the second segment 202b can be joined to each other to form a single gas supply pipeline. In some embodiments, the first segment 202a and the second segment 202b can be configured to be joined to each other in a single configuration. For example, the first segment 202a may have a predetermined chamber end (e.g., the end closest to the chamber 114 or humidification unit 108 along the direction of the flow of humidified gas to the patient) and a predetermined patient end (e.g., the end closest to the patient along the direction of the flow of humidified gas to the patient), the chamber end being configured to connect to components in the chamber 114 and / or humidification unit 108. The second segment 202b may have a predetermined chamber end and a predetermined patient end, where the chamber end is configured to connect only to the patient end of the first segment 202a. The chamber end of the first segment 202a may be configured not to connect to any end of the second segment 202b. Similarly, the patient end of the first segment 202a may be configured not to connect to the patient end of the second segment 202b. Similarly, the patient end of the second segment 202b may be configured not to connect to any end of the first segment 202a. Therefore, the first segment 202a and the second segment 202b can be configured to connect in only one direction to form a single gas supply pipeline.In some embodiments, the first segment 202a and the second segment 202b can be configured to be joined in various configurations. For example, the first segment 202a and the second segment 202b can be configured not to include a predetermined patient end and / or a predetermined chamber end. As another example, the first segment 202a and the second segment 202b can be configured such that the patient end and / or chamber end of the first segment 202a can be joined to the chamber end or patient end of the second segment 202b. Similarly, the first segment 202a and the second segment 202b can be configured such that the chamber end and / or patient end of the second segment 202a can be joined to the patient end or chamber end of the second segment 202b.

[0046] The respiratory humidification system 100 includes an intermediate connector 214, which can be configured to electrically couple the elements of the first segment 202a and the second segment 202b of the inspiratory limb 202. The intermediate connector 214 can be configured to electrically couple the heater wire 206a of the first segment 202a to the heater wire 206b of the second segment 202b, enabling control of the heater wires 206a and 206b using the control device 122. The intermediate connector 214 can be configured to electrically couple the second sensor 204b of the second segment 202b to the first sensor 204a of the first segment, allowing the control device 122 to acquire the respective outputs of the sensors. The intermediate connector 214 may include electrical components that enable selective control of the heater wires 206a and 206b, and / or selective reading of the sensors 204a and 204b. For example, the intermediate connector 214 may include electrical components that transmit power through the first heater wire 206a in a first mode and through the first and second heater wires 206a and 206b in a second mode. Examples of electrical components included in the intermediate connector 214 include, but are not limited to, resistors, diodes, transistors, relays, rectifiers, switches, capacitors, inductors, integrated circuits, microcontrollers, microprocessors, RFID chips, wireless communication sensors, and optical sensors. In some embodiments, the intermediate connector 214 may be configured inside the intake limb 202 such that it is substantially shielded from external elements (for example, less than 1% of water, particulate matter, contaminants, etc. from the environment outside the intake limb 202 come into contact with the intermediate connector 214). In some embodiments, some of the electrical components in the intermediate connector 214 may be configured to be physically isolated from the humidifying gas inside the intake limb 202 in order to reduce or prevent damage that may occur due to exposure to moisture. In some embodiments, the intermediate connector 214 may include relatively inexpensive passive electrical components to reduce costs and / or increase reliability.

[0047] The inspiratory limb 202 may contain sensors 204b, optionally sensor 204a, within each segment 202b, 202a of the inspiratory limb. The first sensor 204a can be positioned near the incubator 208 and near the end of the first segment 202a, so that the parameters derived from the first sensor 204a correspond to the parameters of the humidifying gas entering the second segment 202b. The second sensor 204b can be positioned near the end of the second segment 202b, so that the parameters derived from the second sensor 204b correspond to the parameters of the humidifying gas supplied to the patient or user. The output of sensors 204a (if present) and 204b can be transmitted to the control unit 122 as feedback for use in controlling the power supplied to the heating elements 206a, 206b of the segments 202a, 202b of the inspiratory limb. In some embodiments, one or both of sensors 204a and 204b may be a temperature sensor, a humidity sensor, an oxygen or gas concentration / composition sensor, a flow sensor, a pressure sensor, etc. The temperature sensor may be any suitable type of temperature sensor, including, but not limited to, a thermistor, a thermocouple, a digital temperature sensor, a transistor, etc. Parameters provided by or derived from the sensors may include, but not limited to, temperature, humidity, oxygen content, flow rate, or any combination thereof.

[0048] The control device 122 can be configured to control the heater wires 206a and 206b, receive feedback from sensors 204a (if present) and / or 204b, provide logic for controlling power to the heater wires 206a and 206b, adjust the control of the heater wires 206a and 206b in accordance with readings from sensors 204a (if present) and / or 204b, detect the presence of the second segment 202b of the intake limb 202, derive parameters from readings from sensors 204a (if present) and / or 204b, and so on. In some embodiments, the control device 122 includes a power supply configured to supply power to the heater wires. The power supply may be AC ​​or DC. In some embodiments, the control device 122 can receive input from a heater plate sensor 130. The heater plate sensor 130 can provide the control device 122 with information regarding the temperature and / or power consumption of the heater plate 120. In some embodiments, the control unit 122 can receive input from one or more flow sensors 132. Any suitable sensor 132 can be used, and the sensor 132 can be positioned between the ambient air and the humidification chamber 114, or between the pressurized gas source 102 and the humidification chamber 114. In the illustrated system, the sensor 132 is positioned at the inlet port 124 of the humidification chamber 114. The sensor 132 can sense one or more of the following: flow rate, temperature, humidity, pressure, gas concentration, or gas flow composition. In some embodiments, the control unit 122 can receive input from one or more sensors 133. One or more sensors 133 can be positioned at or near the outlet port 126 of the humidification chamber 114. One or more sensors 133 may be a temperature sensor, a humidity sensor, an oxygen sensor, or a gas concentration / composition sensor, a flow sensor, a pressure sensor, etc. The temperature sensor may be any suitable type of temperature sensor, including, but not limited to, thermistors, thermocouples, digital temperature sensors, transistors, etc. Parameters provided by or derived from the sensor may include, but not limited to, temperature, humidity, oxygen content or composition / concentration of other gases, flow rate, pressure, or any combination thereof.

[0049] Any suitable patient interface may be incorporated. Patient interface is a broad term and is given the usual customary meaning to those skilled in the art (i.e., not limited to special or customized meanings), but includes, but is not limited to, masks (such as tracheal masks, face masks, and nasal masks), nasal cannulas, surgical cannulas for laparoscopic or keyhole surgery, tracheostomy tubes or interfaces, and nasal pillows.

[0050] Segmented inspiratory limbs Figure 2A shows a portion of a segmented inspiratory limb 202 for use with a respiratory humidification system 100, the segmented inspiratory limb 202 comprising a first segment 202a and a second segment 202b, and having an intermediate connector 214, the intermediate connector 214 is configured to connect a first heater wire 206a located in segments 202a and 202b to a second heater wire 206b, and a first sensor 204a (if present) to a second sensor 204b. The coupling of the two segments 202a and 202b may include mechanically coupling the segments to form a single conduit through which humidified gas can be delivered to the user, where the mechanical coupling of segments 202a and 202b allows for the electrical coupling of the respective heater wires 206a and 206b and the respective sensors 204a (if present) and 204b by the intermediate connector 214.

[0051] The segmented intake limbs 202 may comprise a structure 216 that forms a lumen through which a humidifying gas can pass. The structure 216 may include a path formed in the wall of the structure 216 configured to house a heater wire 206a or 206b, thereby shielding the heater wire 206a or 206b from the humidifying gas traveling through the lumen and / or covering it from exposure by the outer surface of the structure 216. For example, the structure 216 may be a helical composite tube, and the heater wire path may be a coil formed inside the tube. The structure 216 may comprise any type of suitable material, and may include thermal insulation and / or flexible materials. In some embodiments, the structure 216 and the intermediate connector 214 may be configured such that the heater wires 206a and 206b wind around the intermediate connector 214 so as to be electrically coupled to the intermediate connector 214 when the first segment 202a and the second segment 202b are mechanically coupled. In some embodiments, the first segment 202a and / or the intermediate connector 214 may also be configured to eliminate flying leads for connecting to the second segment 202b, thereby facilitating the connection of the second segment 202b to the first segment 202a.

[0052] The structure 216 at the complementary ends of the first segment 202a and the second segment 202b can be configured to accommodate an intermediate connector 214. Thus, the intermediate connector 214 may be located inside the intake limb 202. In some embodiments, the complementary ends of the first segment 202a and the second segment 202b can be configured to shield the intermediate connector 214 from the humidifying gas traveling through the intake limb 202. In some embodiments, the intermediate connector 214 is located inside the intake limb 202 and shielded from the humidifying gas in the conduit, thereby reducing or preventing exposure of electrical connection wires at the intermediate connector 214.

[0053] In some embodiments, the first heater wire 206a may comprise two wires 218 and 220, and the second heater wire 206b may comprise two wires 222 and 224. The two wires 218 and 220 of the first segment 202a can be electrically coupled to each other via an electrical component 228, and the electrical coupling creates an electrical path through wire 218, at least a portion of the electrical component 228, and wire 220. Similarly, the two wires 222 and 224 of the second segment 202b can be electrically coupled to each other via an electrical component 228 and / or electrically short-circuited to each other at the end of segment 202b opposite to the intermediate connector 202b via a patient end connector (not shown), which is described in more detail herein with reference to, for example, Figures 3A, 3B, 8A, 8B, 9, and 13. By connecting wires 222 and 224 of the second segment 202b with an intermediate connector 214, the electrical connections at the patient end of the inspiratory limb 202 are reduced or eliminated, which can reduce cost, system complexity, and / or risk to the patient.

[0054] The intermediate connector 214 can be configured so that a single control device can control power to the heater wires 206a and 206b, which may be the humidifier control device 122 described herein with reference to Figure 1. In some embodiments, the humidifier control device 122 controls the heater wires without additional control functions located in the intermediate connector 214. For example, the intermediate connector 214 may include passive components that do not have logic circuits, and these passive components supply power to the heater wires 206a and / or 206b selected by the control device 122. This allows the intermediate connector 214 to be designed using relatively inexpensive components, thereby reducing design complexity.

[0055] In some embodiments, heating of segments 202a and 202b can be achieved using up to four wires within each segment 202a, 202b. For example, in the first segment 202a, the four wires may include a first heater wire 218, a second heater wire 220, a signal sensor wire 228, and a feedback sensor wire 230. In the second segment 202b, the four wires may include a first heater wire 222, a second heater wire 224, a signal sensor wire 232, and a feedback sensor wire 234. By connecting the second heater wires 222 and 224 to the first heater wires 218 and 220 at connection point 226, and by connecting the second sensor wires 232 and 234 to the first sensor wires 228 and 230 at connection point 226, the control device can be configured to individually supply power to the first heater wire 206a and the second heater wire 206b, and to individually read sensor data from sensors 204a (if present) and 204b, without including more than five wires in segment 202a or 202b. In some embodiments, control of the heater wires 206a and 206b, and reading of sensors 204a (if present) and 204b may be achieved using three or fewer wires within each segment (e.g., using three wires, or using two wires), or using five or more wires within each segment (e.g., using five wires, six wires, seven wires, eight wires, or using nine or more wires). In one exemplary embodiment, each segment may have a different number of wires, so that segments with more wires are relatively less flexible than segments with fewer wires. For example, segment 202a may contain eight wires, while segment 202b may contain only four wires. In this example, segment 202a is relatively less flexible than segment 202b (which is relatively more flexible). In another exemplary embodiment, the second elongated member may include second and third elongated members (i.e., using two-start extrusion).Such second and third elongated members may be separated by windings of a continuous first elongated member, or they may be adjacent to each other between continuous windings of the first elongated member. In this exemplary embodiment, each of the second and third elongated members may include one wire or two or more wires. In this way, a person skilled in the art can ensure that adequate physical space is provided for the wires and that the wires are adequately insulated from each other to prevent sparking or short circuits.

[0056] The intermediate connector 214 may include an electrical component 228 configured to allow the control device 122 to selectively control the heater wires 206a and 206b. The control device 122 can be configured to control the heating of the inspiratory limb 202 using two modes: a first control mode which includes providing power to the heater wire 206a in the first segment, and a second control mode which includes providing power to the heater wires 206a and 206b in the first and second segments 202a and 202b. Thus, the control device 122 can be configured to control the heater wire sections individually. This feature allows the control device 122 to control the heating of the inspiratory limb 202 by controlling only the heating of the inspiratory limb according to the first control mode when the second segment 202b is absent, thereby allowing the respiratory humidification system 100 to be used in various situations without modifying the control device 122 or the humidification unit 108. In some embodiments, the control mode may include a mode in which power is supplied only to the heater wire 206b in the second segment 202b. In some embodiments, the control device 122 includes a power supply that provides current. The first and second control modes may be based at least in part on the voltage supplied by the power supply, with a positive voltage or positive current triggering the first control mode and a negative voltage or negative current triggering the second control mode. In some embodiments, the power supply provides rectified AC or DC power to the heater wires 206a, 206b, and a change in rectification or polarity triggers a change in the control mode. By switching the control mode, control of heating in the breathing circuit 200 can be achieved using any power supply capable of switching the polarity of the output signal. In some embodiments, the amount of power supplied to the heater wires 206a, 206b can be adjusted by adjusting the duty cycle of the power applied to the heater wires 206a, 206b. For example, pulse width modulation (PWM) can be used to power the heater wires 206a and 206b, and the duty cycle of the PWM can be adjusted to control the power being supplied.In another example, the amount of power supplied to the heater wires 206a and 206b can be adjusted by controlling the amplitude of the power signal.

[0057] The intermediate connector 214 may include an electrical component 230 configured to allow the control device 122 to selectively read sensors 204a (if present) and 204b. Selective reading can be achieved by using a current source, where applying a positive current across wires 228-230 allows the control device 122 to measure a signal from the first sensor 204a, and applying a negative current across wires 228 and 230 allows the control device 122 to measure signals from the second sensor 204b (if the first sensor 204a is present), or from both the first sensor 204a and the second sensor 204b. The control device 122 can use the readings from sensors 204a (if present) and 204b to adjust the power to the heater wires 206a and 206b, for example, by using pulse width modulation. A first sensor 204a (if present) can be positioned near the connection point or intersection of the first segment 202a and the second segment 202b and provides the control unit 122 with parameters of the gas entering the second segment 202b (which may correspond to entering an incubator or other such area with a different ambient temperature). A second sensor 204b can be positioned at the patient end of the second segment 202b and provides the control unit 122 with parameters of the gas being supplied to the patient, or the gas parameters in front of the patient's upstream end piece, such as a Y-piece. The control unit 122 can use these readings to adjust the power to the heater wires 206a, 206b to maintain the gas temperature at the patient end of the inspiratory limb 202 at a target temperature or an appropriate temperature. The target temperature or appropriate temperature may vary, at least in part, depending on the application and environment in which it is used, and may be approximately 37°C, approximately 40°C, at least approximately 37°C and / or approximately 38°C or lower, at least approximately 36.5°C and / or approximately 38.5°C or lower, at least approximately 36°C and / or approximately 39°C or lower, at least approximately 35°C and / or approximately 40°C or lower, at least approximately 37°C and / or approximately 43°C or lower, or at least approximately 39.5°C and / or approximately 40.5°C or lower. In some embodiments, the second sensor 204b may be positioned inside the incubator but not attached to the breathing circuit.For example, the temperature of the second segment 202b can be calculated by measuring parameters inside the incubator.

[0058] The control device 122 can independently control the amount of power supplied in the first and second control modes, as described herein. Based at least in part on feedback from sensors 204a (if present) and / or 204b, the control device 122 can independently adjust the power supplied in the first and second control modes, thereby changing the ratio of heater power between the first segment 202a and the second segment 202b.

[0059] In some embodiments, including the first sensor 204a, the first sensor 204a is positioned in the gas flow inside the intake limb 202. In some embodiments, the intermediate connector 214 or the first segment 202a may include mechanical components that reduce turbulence in the gas flow across the first temperature sensor 204a, which can improve the accuracy of the sensor 204a readings. For example, the mechanical connector may have an aerodynamic cross-section. In some embodiments, mechanical components that reduce turbulence (e.g., cross member members inside the intake line) also fix the sensor 204a in the gas flow. In some embodiments, the intermediate connector 214 and mechanical components are configured to insulate the sensor 204a from electrical components located in the intermediate connector 214, which may be advantageous, for example, if the sensor 204a is a temperature sensor.

[0060] In some embodiments, the intermediate connector 214 includes additional connection points in addition to the connection point 26 shown in Figure 2A. These additional connection points can be used to incorporate further functionality into the breathing circuit, such as a memory device (PROM, or flash memory, or other suitable type of memory), a microcontroller, additional circuitry, etc. In alternative embodiments, the second segment may be removably coupled to the first segment via the intermediate connector. The intermediate connector may include a socket or area for receiving a corresponding connector on the second segment. The connector on the second segment and the intermediate connector form electrical and pneumatic connections with the second segment, and the first and second segments can be joined via the intermediate connector.

[0061] Exemplary segmented inspiratory limb with connector having microcontroller Figure 2B shows an exemplary embodiment of a respiratory humidification system 100 that utilizes a microcontroller in an intermediate connector 214 to measure data for controlling heating and to read sensor values ​​at the inspiratory limb 202. In some embodiments, one or more microcontrollers can be incorporated into the sensor cartridge, humidifier, intermediate connector 214, or any combination thereof. When incorporated into, for example, the sensor cartridge, the microcontroller provides similar functionality to that described herein. The illustrated exemplary embodiment uses one heater wire, i.e., the wire connected to VN, as a common reference, and connects two heater wires HW1, HW2 and a sensor wire to the common reference. The exemplary embodiment also converts the readings from both sensors 204a, 204b into digital signals at the intermediate connector 214 and transmits them to the humidifier control device 122. This can reduce or eliminate isolation issues by referencing sensors 204a (if present), 204b, with respect to a common reference point and transmitting digital parameter readings that can pass through an optocoupler of a signal-isolating control device 122, as described herein with reference to Figure 2E. Using this exemplary embodiment, two independent control channels may be able to provide desired, selected, or defined heating control by heating only the first section 202a of the intake limbs 202a, 202b or by heating the first and second sections together.

[0062] Figure 2C shows a block diagram of an intermediate connector 214 for the inspiratory limb 202, which uses a microcontroller. The microcontroller can be used to measure analog signals from thermistors 204a and 204b and convert the analog signals to digital signals using an analog-to-digital converter (ADC). The converted digital signals can be transmitted to the humidifier control device 122 on a single data line. The data line can be used to enable communication between the microcontroller and the humidifier control device 122 to provide temperature data. Power can be supplied to the microcontroller using the data line by pulling the data line high in the humidifier control device 122 when no data is being transmitted. The power module and data line converter may include a capacitor and a diode, with the capacitor charging when the data line is high. The charged capacitor can be used to supply power to the microcontroller when the data line is being used for communication. A schematic diagram of an exemplary power module and data line converter is shown in Figure 2D. In another exemplary embodiment, sensors 204a (if present), 204b may sense parameters other than temperature, such as flow rate, humidity, and pressure. In another exemplary embodiment, sensors 204a (if present), 204b are not thermistors but some other sensing component, such as an optical sensor, a capacitive sensor, a resistive sensor, or any other conventional sensor known in the Art.

[0063] Temperature sensing using this configuration can be achieved by using a current or voltage source in the intermediate connector 214 to drive the thermistor, thereby allowing the thermistor to be read by the microcontroller. This can be done, for example, using a transistor or operational amplifier. Data line communication can be achieved using a time slot-based method in which each logic level can be transmitted and read in a predefined time slot. In this way, bidirectional communication between the humidifier control device 122 and the microcontroller can be enabled using a single wire.

[0064] The humidifier control device 122 may include a DC power supply referenced to VN. It may also include a capacitor that can be charged when the heater wire is on and can supply power to the microcontroller when the heater wire is off. The humidifier control device 122 may include a dual optocoupler circuit 1200, as shown in Figure 2E. The dual optocoupler circuit can be used to isolate signals and enable bidirectional data communication between the control device 122 and the power supply.

[0065] In some embodiments, calibration data can be stored in the microcontroller and read when the breathing circuit is connected. In some embodiments, a part identification number or serial number can be stored to determine the manufacturer of the connected circuit.

[0066] Intermediate connector board Figures 2F and 2G show an exemplary intermediate PCB 250 of the intermediate connector 214, with each figure showing two sides of the intermediate PCB 250. The intermediate PCB 250 includes connection pads 252 and 254 for heater wire and sensor connections. The connection pads 252 and 254 are configured to be on both sides of the intermediate PCB 250 to facilitate connection with the heater wire, which is spirally wound around the intake limb.

[0067] The intermediate PCB 250 includes sensor connection pads 256 for sensors such as thermistors or other temperature measuring components, humidity sensors, or flow sensors. Sensors can be coupled to diodes via signal connection pads 258 located on the intermediate PCB 250. As shown in the figure, the intermediate PCB 250 includes a gap 262 configured to thermally isolate the sensor from other electrical components and tracks. In some embodiments, the gap 262 can be filled with insulating material to further thermally isolate the sensor connected to the sensor connection pad 256. Furthermore, the intermediate PCB 250 can be configured, for example, using protrusions 257, to position the sensor away from other active and / or passive electrical components.

[0068] The intermediate PCB 250 includes a power connection pad 260 for a diode electrically coupled to a heater wire via an electrical track located on the intermediate PCB 250. The diode may be diode D1, as described with reference to Figures 2K and 2M. The power connection pad 260 can be electrically and thermally coupled to a heat sink 264 to aid in heat dissipation and reduce or minimize the impact on the accuracy of parameter readings of the sensor coupled to the sensor connection pad 256.

[0069] Figures 2H and 2I show exemplary embodiments of an intermediate connector 214 comprising an intermediate PCB 250 and an intermediate connecting element 263. The intermediate connecting element 263 can be configured to guide a portion of the humidified gas flowing through the intake limb through a conduit formed by the intermediate connecting element 263. An optional sensor on the intermediate PCB 250 can then provide a signal corresponding to parameters of the gas flowing through the intermediate connecting element 263, which represent at least one characteristic of the humidified gas at that time in the intake limb (e.g., temperature, humidity, flow rate, oxygen content, etc.). In some embodiments, the intermediate connecting element 263 is configured to provide mechanical support for the intermediate PCB 250 and to position the intermediate PCB 250 within the intake limb. In some embodiments, the intermediate connecting element 263 is configured to provide mechanical support for joining two segments of the intake limb together in or near the intermediate connector 214.

[0070] The intermediate connector 214 includes a first connection pad 252 on the first side of the intermediate PCB 250 and a second connection pad 254 on the second side of the intermediate PCB 250, the second side being on the opposite side of the intermediate PCB 250. The first and second connection pads 252, 254 can be configured to provide electrical contacts for heater wires in the first and second segments of each of the segmented intake limbs, as described herein. In some embodiments, the heater wires in the segments of the intake limb are helically wound. The intermediate PCB 250 is configured to electrically couple the helically wound heater wires and / or signal wires (e.g., temperature sensor wires) in the first segment to the helically wound heater wires and / or signal wires in the second segment.

[0071] In some embodiments, the intermediate PCB 250 includes a first portion extending across the lumen formed by the intermediate connecting element 263 along the diameter or chord line, and the portion of the intermediate PCB 250 generally bisects at least a portion of the gas flow path. The first portion of the intermediate PCB 250 can be overmolded with an overmolding composition. The intermediate PCB 250 may include a second portion 251 adjacent to the first portion, projecting outward from the outside of the intermediate connecting element 263 in the direction away from the lumen. The second portion 251 of the intermediate PCB 250 includes one or more connecting pads 252 configured to receive one or more wires from the first segment of the inspiratory limb. The intermediate PCB 250 may include a third portion 253 adjacent to the first portion, projecting outward from the outside of the intermediate connecting element 263 in the direction away from the lumen and in the direction opposite to the second portion 251. The third portion 253 may include one or more connection pads 254 located in an intermediate PCB 250 configured to receive one or more wires from the second segment of the inspiratory limb. The intermediate PCB 250 may include one or more conductive tracks configured to electrically couple one or more connection pads 252 of the second portion 251 to one or more connection pads 254 of the third portion 253, thereby providing an electrical connection between the wires of the first segment and the wires of the second segment of the inspiratory limb.

[0072] Intermediate connector circuit Figure 2J shows a schematic of an exemplary intermediate connector 214, which includes an active rectifier power supply for supplying power to heater wires in the segmented inspiratory limb of the breathing circuit, and the circuit is configured to supply power to heater wires R1 and R2 in the first segment of the inspiratory limb in a first mode, and to supply power to heater wires R1, R2, R3, and R4 in both segments in a second mode. Alternatively, power can be applied through heater wires R1 and R2 (where the resistors are the heater wires) or through heater wires R1, R2, R3, and R4 by providing diodes D1 and D2 and switches S1 and S2 in the intermediate connector 214.

[0073] The power supply is indicated in the figure using the symbols VP and VN, which correspond to the terminals of the power supply. In one embodiment, the voltage source is an alternating current (AC) power supply. Alternatively, the power supply may be a direct current (DC) power supply. Although described as diodes in this embodiment, D1 and D2 may include any of several different types of flow control devices, such as, but are not limited to, rectifiers, transistors, relays, switches, triacs, MOSFETs, thyristors (SCRs), thermostats, etc.

[0074] Switches S1 and S2 switch between the VP and VN terminals of the power supply. In one embodiment, switches S1 and S2 are switched every half cycle of the AC power cycle, thereby drawing approximately equal current from the power supply during each half cycle. Using the circuit shown in Figure 2B, heaters R1, R2, R3, and R4 can be controlled in two control modes: the first control mode corresponds to supplying power only to R1 and R2, and the second control mode corresponds to supplying power to R1, R2, R3, and R4. To supply power only to heaters R1 and R2 in the first segment 202a (which corresponds to the first control mode), during the positive cycle from the power supply, switch S1 is connected to VP and switch S2 is connected to VN, and during the negative cycle from the power supply, switch S1 is connected to VN and switch S2 is connected to VP. In the first control mode, current flows through R1, R2, and D1, and D2 prevents current from flowing through R3 and R4. To supply power to heaters R1, R2, R3, and R4 in the first and second segments 202a and 202b (corresponding to the second control mode), during a positive cycle from the power supply, switch S1 is connected to VN and switch S2 is connected to VP, and during a negative cycle from the power supply, switch S1 is connected to VP and switch S2 is connected to VN. In the second control mode, current flows through R1, R2, R3, R4, and D2, with D1 preventing current from flowing through the wires and short-circuiting without passing through heaters R3 and R4. Switching of switches S1 and S2 can be achieved by hardware or software that adds logic to the system. In some embodiments, switching of S1 and S2 is performed at the zero crossing of the AC power circuit. In some embodiments, the falling and rising edges of the zero crossing circuit are not delayed by the same amount, and the circuit is inactive near the zero crossing. Thus, switching of switches S1 and S2 can be performed with or without zero crossing switching detection and / or logic.

[0075] Diodes D1 and D2 may lose power and therefore generate heat within the circuit. In some embodiments, Schottky diodes may be used if it is desirable to reduce power loss in relatively high-temperature environments. Schottky diodes can be operated near their maximum junction temperature to reduce or minimize power loss, which may be desirable in certain implementations of the respiratory humidification systems described herein. In some embodiments, the heat generated by the diodes may affect the temperature reading of sensor 204a (if present). To reduce this effect, the diodes may be thermally connected to the airflow path of the circuit. To reduce this effect and dissipate the heat generated by the diodes, a heat sink or pad thermally coupled to the ambient environment may be included in the intermediate connector 214. To reduce this effect and the effect of other components on the intermediate connector 214, the sensor 204a (e.g., a thermistor or other temperature sensor) may be insulated from its components and positioned relatively far from the other components, as described with reference to Figures 2F and 2G.

[0076] Figure 2K shows another schematic of an exemplary intermediate connector 214, which includes an active rectifier power supply for supplying power to heater wires in the segmented inspiratory limb of the breathing circuit, and the circuit is configured to supply power to heater wires R1 and R2 in a first segment of the inspiratory limb in a first mode, and to supply power to heater wires R1, R2, R3, and R4 in both segments in a second mode. As shown in Figure 2K, only diode D1 may be provided, and the power path through heater wires R1 and R2, or through heater wires R1-R4, can still be controlled in the same manner as described above with respect to Figure 2J. Diode D2 shown in the circuit of Figure 2J is omitted. The circuit shown in Figure 2K with only one diode D1 reduces the heat generated by the circuit, lowers component costs, and allows for a smaller circuit board. The remainder of the circuit shown in Figure 2K operates in a similar manner to that described in Figure 2J. In the embodiment without D2, as shown in Figure 2K, most of the current flows through R1, R2, and D1, and only the residual current flows through R3 and R4. The residual current through R3 and R4 can be ignored and therefore does not affect the performance of the humidification system.

[0077] In addition to the AC operation described with respect to Figures 2J and 2K, similar circuits can also be operated using a DC power supply. Switches S1 and S2 can be switched based, for example, on time, the output current of the power supply, feedback from a sensor, or at least in part on other control inputs. In such embodiments, the circuits shown in Figure 2J or Figure 2K can be used to control the heaters R1, R2, R3, and R4 in two control modes, where the first control mode corresponds to supplying power to R1 and R2 only, and the second control mode corresponds to supplying power to R1 through R4. To supply power to heaters R1 and R2 only in the first segment 202a (which corresponds to the first control mode), switch S1 is connected to VP and switch S2 is connected to VN. In the first control mode, current flows through R1, R2, and D1. D2 prevents current from flowing through R3 and R4 in the circuit shown in Figure 2J. However, as shown in Figure 2K, D2 is an optional component. To supply power to heaters R1, R2, R3, and R4 in the first and second segments 202a and 202b (corresponding to the second control mode), switch S1 is connected to VN and switch S2 is connected to VP. In the second control mode, current flows through R1, R2, R3, and R4, and D1 prevents current from flowing through the wires and short-circuiting by bypassing heaters R3 and R4. As previously mentioned, switching can be achieved by hardware or software that adds logic to the system.

[0078] Sensor circuit Figures 2L and 2M show exemplary circuit diagrams within the respiratory humidification system 100, where circuit 600 is configured to read data from two sensors R1 and R2. Referring to Figures 2L and 2M, sensors R1 and R2 are represented using resistors, but any suitable type of sensor can be used, for example, temperature sensors, humidity sensors, flow sensors, oxygen sensors, etc., without limitation. In some embodiments, the sensors may be temperature sensors such as thermistors. In such embodiments, sensors R1 and R2 represent a first thermistor at the intermediate connector 214 and a second thermistor at the patient end of the respiratory circuit 200 (e.g., the patient end connector), respectively. The two thermistors R1 and R2 can be measured using two wires within the respiratory circuit 200, with circuit 600 together with a current or voltage source and switch in the humidifier control device 122. Refer to Figures 2L and 2M. This explanation pertains to thermistors, but is applicable to other suitable sensors that affect the voltage and / or current supplied to the associated circuit.

[0079] To selectively read sensors R1 and R2, current is supplied via lines 602 and 604 in either polarity. To measure patient-end sensor R2, the humidifier control device 122 sets a switch to ground the upper current source. Then, current flows from the bottom current source through R2 and through the switch to ground. Diode D1 prevents the current from flowing through R1. The humidifier control device 122 can be configured to measure the voltage drop from the bottom current source to ground and derive the resistance of sensor R2 based at least in part on the supplied current and the measured voltage. To measure sensor R1 positioned in the intermediate connector 214, the humidifier control device 122 can read patient-end sensor R2 and record the result. Then, the humidifier control device 122 can set a switch to ground the bottom current source. Then, current flows from the upper current source through R1 and R2 and through the switch to ground. The humidifier control device 122 can be configured to measure the voltage drop from the upper current source to ground and derive the resistance of sensor R1 based at least in part on the supplied current, the measured voltage, and the recorded result from the measurement of the resistance of R2. In some embodiments, the voltage drop across D1 is taken into account when deriving the resistance of R1. In the embodiment shown in Figure 2L, the temperature of diode D1 can be calculated by placing D1 near R1, and this temperature can be used to calculate the voltage drop across D1. One possible advantage of the configuration shown in Figure 2L is that the measurement of sensor R2 at the patient end may be more accurate because the measurement is performed without passing through a diode, as illustrated in the embodiment of Figure 2M. Passage through a diode can introduce uncertainty or error.

[0080] In some embodiments, an additional diode D2 can be added to the intermediate connector 214, as shown in Figure 2M. In such embodiments, the humidifier control device 122 can be configured to measure sensors R1 and R2 in the same manner as in the embodiments shown in Figure 2L and described above. The difference is that when measuring sensor R1, diode D2 obstructs the flow of current through R2, so that current flows through R1 and D1 but not through R2. In this way, the measurement of sensor R1 can be substantially isolated or separated from the measurement of sensor R2. Similar to the derivation of the resistance of sensor R1, the voltage drop across diode D2 can be taken into account when deriving the resistance of sensor R2. By placing D1 and D2 near R1, the temperature of the diodes can be calculated, and this temperature can be used when calculating the voltage drop across D1 and D2, respectively.

[0081] In certain embodiments, measurements of sensors R1 and R2 are performed by software running on a control device connected to the circuits shown in Figures 2L and 2M. The direction and amount of current supplied to the circuit can be controlled by such software. Accurate measurements of the resistances of sensors R1 and R2 can be obtained, for example, by measuring the voltage using an analog-to-digital converter. To minimize or prevent the effects of changes caused by diodes D1 and / or D2, the software can supply two different currents (I1 and I2) in the same direction. This yields two different voltage readings (V1 and V2) corresponding to the two different currents (I1 and I2). Using these two voltages and currents, the software can determine the voltage drop across diodes D1 and D2, and the resistances with respect to sensors R1 and R2. With respect to sensor R1, for example, the voltage drop can be calculated by the following formula: Vdrop = ((V1*I2-V2*I1) / ((V1-V2) / R2+I2-I1)). The resistance of sensor R1 can be calculated using the following formula: R1 = (V2 - Vdrop) / (I2 - V2 / R2). In one embodiment, the calculated Vdrop has a certain error from the measured Vdrop, and this error is corrected by software. In one embodiment, Vdrop is increased by only about 15% as error compensation.

[0082] Segmented medical piping for use with respiratory humidification systems Figure 3A shows a side view of a section of an exemplary composite tube 1201 that can be used with the respiratory humidification system 100 described with reference to Figure 1. The composite tube 1201 can be used as an inspiratory limb 202 and can be configured to provide thermally beneficial properties that help prevent gas condensation along the tube, as described herein. The composite tube 1201 includes a plurality of elongated members that are wound and joined to form a path, where the plurality of elongated members may include one or more of the heater wires described herein. Based at least in part on the heater wires being embedded in the wall of the composite tube 1201, the use of the composite tube 1201 as an inspiratory limb 202 can reduce condensation and rainout and maintain a more desirable or target temperature profile along the length of the inspiratory limb 202. The wall of the composite tube can provide greater thermal mass, which is more resistant to temperature changes and enhances the insulating effect of the wall against the ambient temperature outside the limb 202. As a result, the temperature along the length of the limb 202, including any number of different temperature environments, can be controlled more precisely, and less power or energy can be lost when controlling the temperature of the gas delivered to the patient. In some embodiments, the composite tube 1201 can also be used as the expiratory limb 210.

[0083] Generally, the composite tube 1201 comprises a first elongated member 1203 and a second elongated member 1205. The term "member" is broad and should be interpreted in its usual and customary sense to those skilled in the art (i.e., not limited to any particular or specialized sense), and includes, but is not limited to, a whole, a whole component, and different components. Therefore, while Figure 3A shows an embodiment formed from two different components, it should be understood that in other embodiments, the first elongated member 1203 and the second elongated member 1205 could also represent regions within the tube formed from a single material. Thus, the first elongated member 1203 could be a hollow portion of the tube, and the second elongated member 1205 could be a structural support or reinforcing portion of the tube that adds structural support to the hollow portion. As described herein, the hollow portion and the structural support portion may have a helical configuration. The composite tube 1201 can be used to form the inspiratory limb 202 and / or expiratory limb 210 described herein, the coaxial tube described below, or any other tube described elsewhere in this disclosure.

[0084] In this example, the first elongated member 1203 comprises a helically wound hollow body, forming at least a portion of an elongated tube having a longitudinal axis LA-LA, and also comprises a lumen 1207 extending along the longitudinal axis LA-LA. In at least one embodiment, the first elongated member 1203 is a tube. Preferably, the first elongated member 1203 is flexible. Furthermore, the first elongated member 1203 is preferably transparent, or at least translucent or semi-opaque. Some degree of light transmission allows a caregiver or user to inspect the lumen 1207 for obstruction or contaminants, or to confirm the presence of moisture. A variety of plastics, including medical-grade plastics, are suitable for the body of the first elongated member 1203. Examples of suitable materials include polyolefin elastomers, polyether block amides, thermoplastic copolymer elastomers, EPDM-polypropylene mixtures, and thermoplastic polyurethanes.

[0085] The hollow structure of the first elongated member 1203 contributes to the thermal insulation properties of the composite tube 1201. The insulated tube 1201 is desirable because it prevents or reduces heat loss as described herein. This allows the tube 1201 to deliver gas from the heater-humidifier to the patient while substantially maintaining the regulated state of the gas with less or minimal energy loss.

[0086] The hollow structure of the first elongated member can use air as an insulator. The walls of the composite tube can provide greater thermal mass, which resists temperature changes and enhances the insulating effect of the walls relative to the ambient temperature outside the tube. As a result, the temperature along the length of the tube, including that due to many different temperature environments, can be controlled more precisely, and less power or energy is consumed to control the temperature of the gas delivered to the patient. Furthermore, the hollow structure insulates the gas inside the tube from environmental conditions and changes in environmental conditions, or in some other way. The tube may be exposed to various conditions in various locations in the hospital (e.g., in different wards, but also exposed to incubators, fans, or blankets positioned above part of the tube). The hollow structure acts to insulate the gas from such environmental changes. Further environmental changes may be temperature and humidity changes that can occur in various regions, such as tropical regions.

[0087] In at least one embodiment, the hollow portion of the first elongated member 1203 is filled with gas. The gas may be air, which has a low thermal conductivity (2.62 × 10⁻¹⁰ at 300K). -2 It is desirable due to its high viscosity (W / m·K) and very low cost. Furthermore, it is advantageous that a gas with higher viscosity than air can be used. This is because higher viscosity reduces convective heat transfer. Therefore, argon (17.72 × 10⁻¹⁰ at 300K) is desirable. -3 W / m·K), krypton (9.43 × 10 at 300K) -3 W / m·K), and xenon (5.65 × 10 at 300K) -3Gases such as W / m·K can enhance the thermal insulation performance. These gases are non-toxic, chemically inert, flame-retardant, and commercially available. The hollow portion of the first elongated member 1203 can be sealed at both ends of the tube to substantially retain the gas inside. Alternatively, the hollow portion may be a secondary pneumatic connection line, such as a pressure sample line for transmitting pressure feedback from the patient end of the tube to a control device. The first elongated member 1203 can be optionally perforated. For example, the surface of the first elongated member 1203 may be perforated on the outward-facing surface opposite to the lumen 1207. In another embodiment, the hollow portion of the first elongated member 1203 is filled with a liquid. Examples of liquids include water or other biocompatible liquids with high heat capacity. For example, nanofluids can be used. An exemplary nanofluid with suitable heat capacity includes water and nanoparticles of a substance such as aluminum.

[0088] The second elongated member 1205 is also wound spirally and joined to the first elongated member 1203 between adjacent turns of the first elongated member 1203. The second elongated member 1205 forms at least a portion of the lumen 1207 of the elongated tube. The second elongated member 1205 acts as a structural support for the first elongated member 1203.

[0089] In at least one embodiment, the second elongated member 1205 is wider at the base (proximal to the lumen 1207) and narrower at the top. For example, the second elongated member may be generally triangular, generally T-shaped, or generally Y-shaped. However, any shape that matches the contour of the corresponding first elongated member 1203 is suitable. Alternatively, the shape of the second elongated member may be selected to improve or reduce the flexibility of a given segment. For example, the shape may be a square, rectangle, trapezoid, rhombus or parallelogram, pentagon, or other polygon, or the shape may be a rounded variation of such a shape having rounded corners.

[0090] Preferably, the second elongated member 1205 is flexible to facilitate the bending of the tube. The second elongated member 1205 may be less flexible than the first elongated member 1203. This improves the ability of the second elongated member 1205 to structurally support the first elongated member 1203. For example, the modulus of elasticity of the second elongated member 1205 is preferably 30 to 50 MPa (or about 30 to 50 MPa). The modulus of elasticity of the first elongated member 1203 is less than that of the second elongated member 1205. The second elongated member 1205 may be solid or nearly solid. Furthermore, the second elongated member 1205 can encapsulate or house a conductive material, such as a filament, particularly a heating filament, or a sensor (not shown). The heating filament can minimize the low-temperature surface where condensation from humid air may occur. Furthermore, a heating filament can be used to alter the temperature profile of the gas within the lumen 1207 of the composite tube 1201. Various polymers and plastics, including medical-grade plastics, are suitable for the body of the second elongated member 1205. Examples of suitable materials include polyolefin elastomers, polyether block amides, thermoplastic copolymer elastomers, EPDM-polypropylene mixtures, and thermoplastic polyurethanes. In certain embodiments, the first elongated member 1203 and the second elongated member 1205 may be formed from the same material. The second elongated member 1205 may also be formed from a material of a different color from the first elongated member 1203, and may be transparent, translucent, or opaque. For example, in one embodiment, the first elongated member 1203 may be formed from a transparent plastic, and the second elongated member 1205 may be formed from an opaque blue (or other color) plastic.

[0091] This spirally wound structure, comprising a flexible hollow body and an integral support, can provide compressive resistance while ensuring that the tube wall is flexible enough to allow bending at a short radius without buckling, blockage, or collapse. Preferably, the tube can be bent around a 25 mm diameter metal cylinder without buckling, blockage, or collapse, as defined in the test for increase in flow resistance with bending according to ISO 5367:2000(E). Furthermore, this structure can provide a smooth surface (hole) of the lumen 1207, which helps prevent deposits from forming in the tube and improves gas flow. The hollow body has been found to improve the thermal insulation properties of the tube while keeping it lightweight.

[0092] As described above, the composite tube 1201 can be used as an expiratory tube and / or an inspiratory tube in a breathing circuit, or as part of a breathing circuit. Preferably, the composite tube 1201 is used as at least an inspiratory tube.

[0093] Figure 3B shows the upper longitudinal section of the exemplary composite tube 1201 of Figure 3A. Figure 3B has the same orientation as Figure 3A. This example further illustrates the hollow shape of the first elongated member 1203. As seen in this example, the first elongated member 1203 forms multiple internal air bubbles in its longitudinal section, which are completely sealed inside the composite tube. The internal air bubbles can be filled with air. A portion 1209 of the first elongated member 1203 overlaps with an adjacent winding of the second elongated member 1205. A portion 1211 of the first elongated member 1203 forms the wall (hole) of the lumen.

[0094] It was unexpectedly discovered that having gaps 1213 between adjacent turns of the first elongated member 1203, i.e., between adjacent cells, improves the overall thermal insulation properties of the composite tube 1201. Therefore, in certain embodiments, adjacent cells are separated by gaps 1213. Furthermore, certain embodiments include increasing the thermal resistance (R value) and thus reducing the thermal conductivity of the composite tube 1201 by providing gaps 1213 between adjacent cells. It was also found that this gap configuration improves the flexibility of the composite tube 1201 by allowing bending at a shorter radius. As shown in Figure 3B, the T-shaped second elongated member 1205 can help maintain gaps 1213 between adjacent cells. Nevertheless, in certain embodiments, adjacent cells are in contact. For example, adjacent cells can be joined together as a single unit.

[0095] One or more conductive materials can be arranged within the second elongated member 1205 to heat or sense the gas flow. In this example, two heating filaments 1215 are encapsulated within the second elongated member 1205, each on one side of the “T”-shaped vertical section. The heating filaments (also called heater wires) 1215 include conductive materials such as aluminum (Al) and / or copper (Cu) alloys or conductive polymers. Preferably, the material forming the second elongated member 1205 is selected so as not to react with the metal in the heating filaments 1215 when the heating filaments 1215 reach their operating temperature. The filaments 1215 may be positioned away from the lumen 1207 so as not to be exposed to the lumen 1207. At one end of the composite tube, several pairs of filaments may be formed as a connecting loop.

[0096] In at least one embodiment, multiple filaments are arranged within a second elongated member 1205. The filaments can be electrically connected to one another and share a common rail. For example, a first filament, such as a heating filament, can be arranged on a first side of the second elongated member 1205. A second filament, such as a sensing filament, can be arranged on a second side of the second elongated member 1205. A third filament, such as a grounding filament, can be arranged between the first and second filaments. The first, second, and / or third filaments can be connected to one another at one end of the second elongated member 1205.

[0097] Figure 3C shows a longitudinal cross-section of the bubble body in Figure 3B. As shown, a portion 1209 of the first elongated member 1203 overlapping an adjacent winding of the second elongated member 1205 is characterized by a certain degree of bonding region 1217. A larger bonding region improves the tube's resistance to delamination at the interface between the first and second elongated members. As an addition or alternative, the shape of the bead and / or bubble body can be adapted to increase the bonding region 1217. For example, Figure 3D shows a relatively small bonding region on the left side. Also, Figure 4B shows an even smaller bonding region. In contrast, Figure 3E has a much larger bonding region than that shown in Figure 3D, due to the size and shape of the bead. Figures 4A and 4C also show larger bonding regions. These figures will be discussed in more detail below. While the configurations shown in Figures 3E, 4A, and 4C may be preferred in certain embodiments, it should be understood that in other embodiments, other configurations, including those shown in Figure 3D, Figure 4B, and other variations, may be used if desired.

[0098] Figure 3D shows a longitudinal section of the top of another composite tube. Figure 3D has the same orientation as Figure 3B. This example further illustrates the hollow shape of the first elongated member 1203 and how the first elongated member 1203 forms multiple air bubbles in its longitudinal section. In this example, the air bubbles are completely separated from each other by gaps 1213. A generally triangular second elongated member 1205 supports the first elongated member 1203.

[0099] Figure 3E shows a longitudinal cross-section of the top of another composite tube. Figure 3E has the same orientation as Figure 3B. In the example of Figure 3E, the heating filaments 1215 are positioned further apart from each other than the filaments 1215 in Figure 3B. It has been found that heating efficiency can be improved by increasing the space between heating filaments. Certain embodiments include this implementation. Heating efficiency represents the ratio of the amount of heat entering the tube to the amount of energy leaving or recoverable from the tube. Generally, the greater the energy (or heat) dissipated from the tube, the lower the heating efficiency. To improve heating performance, the heating filaments 1215 can be positioned evenly (or nearly evenly) along the holes in the tube. Alternatively, the filaments 1215 can be positioned at the ends of a second elongated member 1205, which may allow for simpler manufacturing.

[0100] Figure 4A shows a longitudinal cross-section of the upper part of the composite tube. Figure 4A shows one embodiment of the composite tube 1201, in which the first elongated member (e.g., the cellular body) has a large height. In this example, the cellular body has a relatively small radius of curvature and therefore a large curvature. The cellular body is also approximately 3 to 4 times the height of the second elongated member 1205.

[0101] Figure 4B shows a longitudinal cross-section of the top of another composite tube. Figure 4B shows one embodiment of the composite tube 1201, in which the first elongated member (e.g., a cellular body) is flattened at the top. In this example, the cellular body has a very large radius of curvature and a small curvature. The cellular body is also approximately the same height as the second elongated member 1205.

[0102] Figure 4C shows a longitudinal cross-section of the top of another composite tube. Figure 4C shows one embodiment of the composite tube 1201, where the width of the first elongated member (e.g., the bubble) is greater than the height of the first elongated member (e.g., the bubble). In this example, the bubble has a radius of curvature and curvature between that of Figure 4A and that of Figure 4B, and (compared to Figure 4A) the center of the radius with respect to the top of the bubble is outside the bubble. The inflection points on the left and right sides of the bubble are approximately in the center (in the height direction) of the bubble (whereas in Figure 4A they are at the bottom of the bubble). Also, the height of the bubble is approximately twice that of the second elongated member 1205, and the bubble height is between the height of Figure 4A and the height of Figure 4B.

[0103] The configuration in Figure 4A exhibited the minimum heat loss from the tube. The configuration in Figure 4B exhibited the maximum heat loss from the tube. The configuration in Figure 4C had heat loss intermediate between that of the configurations in Figures 4A and 4B. However, the large outer surface area and convective heat transfer in the configuration in Figure 4A resulted in inefficient heating. Therefore, of the three first elongated member (e.g., bubble) configurations in Figures 4A to 4C, Figure 4C was judged to have the best overall thermal characteristics. When the same thermal energy was input to the three tubes, the configuration in Figure 4C produced the greatest temperature rise along the length of the tube. The bubble in Figure 4C is large enough to increase the adiabatic air volume, but not large enough to cause significant heat loss due to convection. The configuration in Figure 4B was judged to have the worst thermal characteristics. That is, the configuration in Figure 4B produced only the smallest temperature rise along the length of the tube. The configuration in Figure 4A had intermediate thermal characteristics and produced a lower temperature rise than the configuration in Figure 4C.

[0104] While the configuration shown in Figure 4C may be preferred in certain embodiments, it should be understood that in other embodiments, other configurations, including those shown in Figure 4A, Figure 4B, and other variations, may be used if desired.

[0105] Table 1 shows the height, outer diameter of the tube, and radius of curvature of the first elongated member (e.g., a bubble body) in the configuration shown in Figures 4A, 4B, and 4C, respectively.

[0106] [Table 1]

[0107] Tube flexibility Figures 5A–5E provide examples of modifications to a first and second elongated member of the composite tube 1201, which can alter the flexibility of the tube. The geometry of the tube 1201 also affects the mechanical properties of the tube. By altering the flexibility and stiffness, the mechanical properties of the tube 1201 can be customized. It should be understood that each modification described below has the effect with respect to thermal insulation (i.e., all other properties are kept the same). However, those skilled in the art will understand that one or more of the modification descriptions below can be used to realize a desired tube with appropriate lumen bore, outer diameter, outer contour, aesthetic appearance, flexibility / stiffness, length, insulation properties, or other desired features. Flexibility of the tube may refer to a specified standard, such as an industry standard, for bending without twisting, blockage, or an excessive increase in resistance to flow within the tube. By increasing flexibility, this disclosure intends to provide a tube that may have higher flexibility than the specified standard. A tube with higher flexibility may indicate that it can bend with a smaller radius of curvature and / or with less force required to bend the tube.

[0108] diameter Figure 5A shows the changes in the diameter of the lumen and the diameter of the first elongated member. Increasing the size of the bubbles in the first elongated member increases the flexibility of the tube 1201. Conversely, smaller bubble sizes create a more rigid region of the tube 1201. For example, the diameter of the first elongated member may be in the range of 1.0 mm (or approximately 1.0 mm) to 6.0 mm (or approximately 6.0 mm).

[0109] Increasing the inner diameter of the tube reduces the flexibility of tube 1201. Conversely, a smaller inner diameter increases the flexibility of tube 1201. For example, the inner diameter of the tube can be within the range of 6.0 mm (or approximately 6.0 mm) to 30.0 mm (or approximately 30.0 mm). By changing the inner diameter of tube 1201, it is possible to have a smaller inner diameter near the patient interface, which can improve patient comfort, enhance aesthetics, and reduce the invasiveness of the interface.

[0110] wall thickness In the example of Figure 5B, the cross-sectional thickness of the inner portion 1211 of the first elongated member 1203 forming the lumen wall is smaller than the thickness of the outer portion. The configuration in Figure 5B creates thinner bubbles near the lumen, so such a configuration allows the inner portion 1211 to be more easily compressed or "bunched" when the composite tube 1201 is bent into an inverted U-shape. Thus, certain embodiments include the recognition that a configuration in which the cross-sectional thickness of the inner portion 1211 is smaller than that of the outer portion can improve the flexibility of the composite tube 1201 by enabling bending at a shorter radius. Furthermore, certain embodiments include the recognition that the overall flexibility of the tube can be improved by providing the first elongated member 1203 having a variable cross-sectional wall thickness. Preferably, the thickness of the inner portion 1211 is smaller than the thickness of the outer portion.

[0111] In at least one embodiment, the thickness of the inner portion 1211 is at least 20% (or about 20%) less than the thickness of the outer portion. For example, in a particular embodiment, the thickness of the inner portion 1211 is at least 30% (or about 30%), at least 40% (or about 40%), at least 50% (or about 50%), or at least 60% (or about 60%) less than the thickness of the outer portion. In a particular embodiment, the thickness of the inner portion 1211 is 27% (or about 27%) less than the thickness of the outer portion. In a particular embodiment, the thickness of the inner portion 1211 is 32% (or about 32%) less than the thickness of the outer portion. In a particular embodiment, the thickness of the inner portion 1211 is 58% (or about 58%) less than the thickness of the outer portion. In a particular embodiment, the thickness of the inner portion 1211 is 64% (or about 64%) less than the thickness of the outer portion.

[0112] The thickness of the outer portion may be in the range of 0.14 mm (or approximately 0.14 mm) to 0.5 mm (or approximately 0.5 mm), preferably in the range of 0.20 mm (or approximately 0.20 mm) to 0.50 mm (or approximately 0.50 mm). The thickness of the inner portion 1211 may be in the range of 0.05 mm (or approximately 0.05 mm) to 0.30 mm (or approximately 0.30 mm), preferably in the range of 0.08 mm (or approximately 0.08 mm) to 0.15 mm (or approximately 0.15 mm).

[0113] pitch Referring to Figure 5C, the winding pitch of the first elongated member 1203 can be changed to affect the flexibility of the tube. Pitch refers to the distance from one winding of one member to the next winding of the same member. For example, pitch can represent the distance from one first elongated member to the next first elongated member, from one second elongated member to the next second elongated member, from the center of one member to the center of the next member, and so on. A smaller pitch can result in a height (HH) greater than the width (WW) of a single longitudinal section cell of the first elongated member 1203. A greater height increases the amount of material sag at the outer wall of the cell of the first elongated member 1203, so such a configuration can improve the flexibility of the composite tube 1201 by allowing bending at a shorter radius. Therefore, certain embodiments include the recognition that the overall flexibility of the tube can be improved by reducing the pitch and providing a first elongated member 1203 having a longitudinal cross-sectional height greater than the longitudinal cross-sectional width. While this exemplary configuration may be preferred in certain embodiments, it should be understood that other configurations and variations may be used as desired in other embodiments. For example, the height of the longitudinal cross-sectional bubbles of the first elongated member 1203 may be less than its width.

[0114] However, those skilled in the art should understand that, generally, a wider pitch provides a more flexible tube (i.e., a bubble with a relatively large WW). For example, a tube with a large height HH and a small width WW will be less flexible than a tube with a large width WW. The cross factor of large HH and large WW may be even more flexible (than small height HH and large width WW), as WW again has a significant influence on flexibility.

[0115] In at least one embodiment, the bubble height (HH) may be in the range of 1.2 mm (or about 1.2 mm) to 10 mm (or about 10 mm), for example, 1.2 mm (or about 1.2 mm), 1.7 mm (or about 1.7 mm), 1.8 mm (or about 1.8 mm), 2.7 mm (or about 2.7 mm), 2.8 mm (or about 2.8 mm), 3 mm (or about 3 mm), 3.2 mm (or about 3.2 mm), 3.5 mm (or about 3.5 mm), 3.8 mm (or about 3.8 mm), 4 mm (or about 4 mm), 4.5 mm (or about 4.5 mm), 7.7 mm (or about 7.7 mm), or 8.2 mm (or about 8.2 mm). In at least one embodiment, the bubble width (WW) may be in the range of 1.7 mm (or about 1.7 mm) to 8 mm (or about 8 mm), for example, 1.7 mm (or about 1.7 mm), 3.2 mm (or about 3.2 mm), 3.5 mm (or about 3.5 mm), 4.0 mm (or about 4.0 mm), 4.2 mm (or about 4.2 mm), 5.2 mm (or about 5.2 mm), 5.5 mm (or about 5.5 mm), 6 mm (or about 6 mm), 7 mm (or about 7 mm), 7.5 mm (or about 7.5 mm), or 8 mm (or about 8 mm).

[0116] The relationship between bubble height (HH) and bubble width (WW) can be expressed as a ratio. When the ratio of bubble height (HH) to bubble width (WW) is 0, the flexibility is lowest. As the ratio increases, the flexibility increases. In at least one embodiment, the ratio of bubble height (HH) to bubble width (WW) may be in the range of 0.15 (or about 0.15) to 1.5 mm (or about 1.5), for example, 0.16 (or about 0.16), 0.34 (or about 3.4), 0.50 (or about 0.50), 0.56 (or about 0.56), 0.57 (or about 0.57), 0.58 (or about 0.58), 0.67 (or about 0.67), 0.68 (or about 0.68), 0.73 (or about 0.73), 0.85 (or about 0.85), 1.1 (or about 1.1), and 1.3 (or about 1.3).

[0117] Bead width Figure 5D shows the variation in the width of the second elongated member. The second elongated member 1205 can be flexible to facilitate bending of the tube. For example, the modulus of elasticity of the second elongated member 1205 is preferably 30-50 MPa (or about 30-50 MPa). The modulus of elasticity of the first elongated member 1203 can be smaller than that of the second elongated member 1205. The second elongated member 1205 may be solid or nearly solid. The width of the second elongated member 1205 can be increased to change the flexibility of the tube. A larger width of the second elongated member 1206 having the same pitch will reduce flexibility (as this also substantially reduces the width of the first elongated member 1203). An excessive width of the second elongated member 1205 will limit the bending radius and may cause the tube to bunch or collapse. The greater width of the second elongated member 1205 at the same pitch also reduces the free length available for bending the inner wall of the first elongated member 1203, thus creating a tube with higher stiffness. It can also improve the bond between the first and second elongated members and reduce the length of sag in the upper portion of the first elongated member.

[0118] Flattened bubbles Figure 5E shows an embodiment of a first elongated member in which the bubble is flattened at the top and solid. The flattened body of the first elongated member may reduce the flexibility of the tube. The flattened bubble section may significantly stiffen the tube. In some embodiments, the flattened bubble may be nearly solid, but may be slightly hollow (not shown).

[0119] Variable stiffness tube Figure 6A shows a longitudinal section view of an exemplary variable-thickness tube 301. Generally, the medical tube 301 comprises a first opening 305, a second opening 307, and an elongated conduit 303 having a longitudinal axis LA-LA. In this example, the elongated conduit 303 generally has a cylindrical shape. Nevertheless, “conduit” is a broad term and should be given in the usual customary meaning to those skilled in the art (i.e., not limited to a special or customized meaning), and without limitation, includes non-cylindrical passages. The lumen 309 extends along the longitudinal axis LA-LA between the first opening 305 and the second opening 307. The conduit 303 has higher stiffness at the position adjacent to the first opening 305 than at the position adjacent to the second opening 307.

[0120] The conduit 303 extends between the first opening 305 and the second opening 307 and comprises a wall 311 surrounding the lumen 309. In this example, the wall 311 is stiffer in the first region 313 of the conduit 303 adjacent to the first opening 305 than in the second region 315 of the conduit 303 adjacent to the second opening 307. The wall 311 may optionally be corrugated or a corrugated profile. As shown in this example, a corrugated profile may consist of alternating outer peaks (or annular projections) and inner troughs (or annular recesses). The outer peaks may correspond to the locations of the maximum inner and outer radii of the elongated conduit, and the inner troughs may correspond to the locations of the minimum inner and outer radii of the elongated conduit. Such a corrugation may be in the form of an annular or helical corrugation. Alternatively, the wall 311 may have a smooth or non-corrugated profile. Optionally, the first opening 305 may be sized and shaped to connect to a humidifying gas source such as the humidifier described above, and the second opening 307 may be sized and shaped to connect to a patient interface. For example, one or more ends may be configured to connect to a connection port that facilitates connection to the patient interface and / or humidifier. Other configurations may also be desirable. For example, in other embodiments, the first opening 305 may be configured to connect to a patient interface, and the second opening 307 may be configured to connect to a ventilator / blower as described above.

[0121] As will be described in more detail below, the tube 301 may optionally include one or more conductive (heating or sensing) filaments. Optional locations for the filaments are as follows: typically loosely spirally arranged within the lumen; typically in combination with an external sheath, in close external contact with the tube wall to fix the conductive filaments in place and prevent heat loss; or embedded in the tube wall.

[0122] Generally, the total length of the tube may be 1.0m to 3.0m (or approximately 1.0m to 3.0m) or 1.0 to 2.0m (or approximately 1.0m to 2.0m). Preferably, the length of the tube is 1.5m (or approximately 1.5m) or 1.8m (or approximately 1.8m). Preferably, the average diameter of the lumen (taking into account the variation in diameter caused by peaks and troughs in an optional waveform) is 9mm to 30mm (or approximately 9mm to 30mm). Preferably, the lumen diameter for adult patients is 20mm (or approximately 20mm) or 22mm (or approximately 22mm). Preferably, the lumen diameter for neonatal patients is 9mm (or approximately 9mm) to 15mm (or approximately 15mm). In fact, the variable stiffness tubing described herein can be used as a replacement for tubing conventionally used in the art, which typically has an average lumen diameter between 9 mm and 30 mm and a length between approximately 1 m and 2.5 m.

[0123] Furthermore, it is preferable that the tubing is resistant to crushing, resistant to flow constraints when bent, resistant to twisting, resistant to changes in length and / or volume under internal pressure, resistant to leakage (<25 mL / min at 6 kPa), has low flow resistance (pressure rise at maximum rated flow rate is less than 0.2 kPa), and is electrically safe. Preferably, the tubing can be bent around a 25 mm diameter metal cylinder without twisting, blockage, or collapse, as defined by the test for increase in flow resistance with bending according to ISO 5367:2000(E).

[0124] Different stiffness between regions Referring again to Figure 6A, preferably, the first region 313 of the conduit 303 adjacent to the first opening 305 has higher stiffness than the second region 315 of the conduit 303 adjacent to the second opening 307. Various embodiments include one or more additional regions between the first region 313 and the second region 315 (e.g., intermediate regions in stiffness characteristics between the first region 313 and the second region 315) having different stiffness characteristics from the first region 313 and the second region 315. For example, a three-region tube 301 can give a better curve profile compared to a two-region tube 301. A schematic diagram of a three-region tube 301 is shown in Figure 6B. This example includes a third region 321 intermediate between the first region 313 and the second region 315.

[0125] Wall composition In at least one embodiment, the wall is formed from an extruded product comprising one or more polymers. Preferred polymers include linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), polypropylene (PP), polyolefin plastomer (POP), ethylene vinyl acetate (EVA), flexible polyvinyl chloride (PVC), or two or more blends of these materials. The polymer constitutes at least 98.4 (or about 98.4), 98.5 (or about 98.5), 98.6 (or about 98.6), 98.7 (or about 98.7), 98.8 (or about 98.8), 98.9 (or about 98.9), 99.0 (or about 99.0), 99.1 (or about 99.1), 99.2 (or about 99.2), 99.3 (or about 99), 99.4 (or about 99.4), 99.5 (or about 99.5), 99.6 (or about 99.6), 99.7 (or about 99.7), 99.8 (or about 99.8), or 99.9 (or about 99.9) weight percent (wt%) of the whole extruded product. In certain embodiments, the extruded article contains 99.488 (or about 99.488) wt% or about 99.49 (or about 99.49) wt% LLDPE.

[0126] In embodiments including a foamed wall, the foamed wall is preferably a single-piece polymer foam formed, for example, by extrusion molding of a single extruded product. The foamed wall can advantageously improve the level of thermal insulation with respect to the lumen compared to the level of thermal insulation provided by a non-foamed wall. Thus, in at least one embodiment, the wall insulates the contents of an elongated conduit (e.g., humidified gas flowing through a gas channel) from the potential cooling effect of the environment surrounding the medical tube (e.g., insulation from ambient air surrounding a breathing circuit, or insulation from a laparoscopic air supply system). The environment surrounding the medical tube may be, for example, a ward or patient room, an operating room, a bedroom at home, or any other place where a patient may be.

[0127] An exemplary method for forming a foam wall involves adding a chemical blowing agent to an extruded product. Chemical blowing agents are sometimes also called foamers. Chemical blowing agents enable the foaming of the extruded material, either as part of the extrusion process or after the extrusion process.

[0128] It should also be understood that other foaming techniques can be employed to form the foam wall, such as physical foaming methods rather than chemical foaming methods. Physical foaming methods involve directly introducing gas into the extruded product under pressure. As the extruded product is pushed out, the pressure is reduced, allowing the gas to expand. For example, one such physical foaming technique involves blowing or injecting gas into the extruded product at or near the extrusion point. Such gases may include nitrogen, carbon dioxide, pentane, or butane.

[0129] sheath In certain embodiments, as shown in Figure 6C, the elongated conduit 303 may further comprise a sheath 327. The sheath 327 is a member that partially or completely encloses the wall 311. The sheath 327 can be fixed to the wall 311 of the conduit 303 at a position along the wall 311, or it may be fixed only to the end of the tube 301. Alternatively, the sheath may be fixed by an intermediate connector 214 of the segmented intake tube 202. The sheath 327 can be used to fix a conductive filament (described later) in place and / or to prevent heat loss due to cold airflow impacting the tube wall 311.

[0130] The sheath 327 can be incorporated into the conduit 303 having a smooth wall (not shown), a composite tube 1201, or a corrugated wall 311, but it may be particularly advantageous to include such a sheath 327 together with the corrugated wall or composite tube. The sheath can trap air between adjacent outer peaks (or annular projections) of the corrugation. This may help to further insulate the gas passing through the lumen 309.

[0131] For example, if the sheath 327 is extruded around the wall 311, such extrusion may be a step following the initial extrusion of the wall 311, i.e., an extrusion step after the wall 311 has been formed. Furthermore, if the outer sheath 327 is, for example, a wrap around the wall 311, the sheath 327 may be constructed in place from a tape or ribbon that is spirally wound around the length of the wall 311. Furthermore, if the outer sheath 327 is pre-formed as a hollow tube, the outer sheath 327 may be fitted around the outside of the wall 311.

[0132] In some embodiments, the sheath can be formed from a mesh, braid, or cloth cover. The size of the filaments of such a sheath may be between 0.05 mm and 1.0 mm (or about 0.05 mm and 1.0 mm). Preferably, the filament size is between 0.25 mm (or about 0.254 mm) and 0.28 mm (or about 2.8 mm). Braided mesh can be manufactured from a variety of materials such as plastic or metal, or natural or synthetic fibers. In one exemplary embodiment, the sheath is preferably formed from polyethylene terephthalate monofilament.

[0133] In one exemplary embodiment, the sheath 27 is preferably a braided mesh surrounding one or more segments of the respiratory circuit limb, and is coupled to the limb only at the end where the respiratory conduit is inserted into the connector. In another exemplary embodiment, the sheath is located outside the respiratory conduit wall and is fixed to the end connector and either around or below the end connector, at the same time as the conduit wall is fixed. The sheath can be fixed by any suitable means known in the art, such as adhesive, friction fit, overmolding, or other conventional fastening methods.

[0134] In one exemplary embodiment, the sheath may be applied to the respiratory conduit as an online process in which the sheath is formed at the same time as the conduit is formed, or alternatively, a pre-fabricated sheath may be applied to the respiratory conduit in a separate process.

[0135] During use, the sheath significantly contributes to attenuating the wave propagation effect of the respiratory circuit limb itself (i.e., attenuating the displacement of the tube). In some embodiments, there is no coupling between the sheath and the respiratory circuit limb along the length of the conduit, but the sheath has been found to greatly improve the displacement of the tube under gas flow (especially high-frequency gas flow). Even more surprisingly, mesh sheaths have been found to have a particularly excellent attenuation effect. This is because when tension is applied to the limb (e.g., during therapy), the mesh tube contracts radially (like a finger trap toy) due to the axial or longitudinal elongation of the mesh, thereby tightening the tube and limiting or resisting any wave propagation or displacement force that may occur. This radial contraction is resisted by the outer surface of the tube wall (e.g., by other surfaces of the first and / or second elongated members of the composite tube), resulting in a strain-limiting effect for the respiratory circuit limb. This effect greatly improves the strength and resistance to displacement force of the respiratory circuit limb, while still allowing for flexible bending during positioning. In this embodiment, it is preferable to select the material, number, weave pitch, and gauge of the braided filaments to improve the stiffness of the conduit. In one exemplary embodiment of the mesh sheath, the mesh is 10 (or about 10) to 1000 (or about 1000) picks per meter. In another exemplary embodiment of the mesh sheath, the mesh is between 100 (or about 100) to 500 (or about 500) picks per meter. In yet another exemplary embodiment of the mesh sheath, the mesh is between 200 (or about 200) to 400 (or about 400) picks per meter. Attenuating the displacement of the tube can generally mean limiting or resisting the wave propagation or displacement force that the tube may experience when the tube is under tension, such as during therapy. This can result in various attenuation effects during therapy, such as a reduction in the magnitude of displacement, a reduction in displacement frequency, a reduction in the curvature of the tube's bend, and / or an overall reduction in the significant movement of the tube.

[0136] A mesh sheath may consist of a single strand or filament, or two or more adjacent strands or filaments. For example, instead of a single strand, a mesh sheath may consist of 2 to 32 adjacent filaments. A sheath may have 1, 2, 4, 8, 16, 32, or 64 or more adjacent strands. To achieve the desired pick per meter, there may be any appropriate number of braids (including one or more filaments as discussed above). For example, there may be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, or 41 or more braids. In one exemplary embodiment, a suitable mesh may have 250 to 350 picks per meter and consist of 36 braids, each containing two adjacent filaments.

[0137] Alternative damping mechanism Those skilled in the art should understand that there are other suitable means of resisting displacement forces and still providing flexibility for bending motion, such as attaching at least one component having a different harmonic frequency response than the tube itself.

[0138] In one exemplary embodiment, the damping mechanism is a spline, or at least one spline. The spline may be inside or outside the tube (in the lumen or on the side wall), may be formed at the same time as the tube or at a different time, may be formed integrally with the tube or not, may extend substantially along the length of the tube segment or only to the partial length of the tube segment, and may be coaxial with the tube or not.

[0139] In another exemplary embodiment, the damping mechanism is at least one stiffening rod (formed of a material that remains flexible under bending forces). The stiffening rod may be inside or outside the tube (in the lumen or on the side wall), may be formed at the same time as the tube or at a different time, may be formed integrally with the tube or not, may extend substantially along the length of the tube segment or only to the partial length of the tube segment, and may be coaxial with the tube or not.

[0140] In one exemplary embodiment, the damping mechanism is at least one rib. The rib may be inside or outside the tube (in the lumen or on the side wall), may be formed at the same time as the tube or at a different time, may be formed integrally with the tube or not, may extend substantially along the length of the tube segment or only to the partial length of the tube segment, may extend axially along the tube or not, may extend radially around the tube or not, may extend perpendicularly to the axis of the tube or not.

[0141] In one exemplary embodiment, the damping mechanism is at least one film. The film may be inside or outside the tube (in the lumen or on the side wall), may be formed at the same time as the tube or at a different time, may be formed integrally with the tube or not, may cover the tube or cover the inside of the tube, may extend substantially along the length of the tube segment or only to the partial length of the tube segment, and may be coaxial with the tube or not.

[0142] In one exemplary embodiment, the damping mechanism is a tape, strip, or string. The tape, strip, or string may be inside or outside the tube (in the lumen or on the side wall), may be formed at the same time as the tube or at a different time, may be formed integrally with the tube or not, may cover the tube or cover the inside of the tube, may extend substantially along the length of the tube segment or only to the length of a portion of the tube segment, and may be coaxial with the tube or not. The tape, strip, or string may contain adhesive on one or more sides that is partially or entirely spread along the length of the tape, strip, or string. Alternatively, the tape, strip, or string may not contain adhesive and may be secured to or inside the tube in any other suitable manner, such as those described elsewhere in this specification. The tape, strip, or string may be spirally wound around the tube. Preferably, if the tube is composed of spirally wound components, the spirally wound tape, strip, or string has a different pitch (looser or tighter pitch) than the spirally wound components of the tube. In alternative embodiments, the tape, strip, or string is not spirally wound. In further exemplary embodiments, the tape, strip, or string may extend longitudinally along the tube. In yet another further exemplary embodiment, the tape, strip, or string includes at least one spirally wound segment and at least one segment that is not spirally wound.

[0143] The end or intermediate connector may also be a structural mechanism for receiving the damping mechanism described above, such as a recess or groove, lip, or slot. For example, in one exemplary embodiment, at least one connector (such as an end connector or intermediate connector) is provided with a recess or groove for receiving the reinforcing spine described above. It should be understood that such a damping mechanism may be secured by the connector by conventional mounting means in the art, such as adhesive, friction fit, or overmolding. Furthermore, it should be understood that such a damping mechanism may consist of any suitable material, such as plastic, metal, natural or synthetic fiber, silicone, or other suitable material including those described elsewhere in this specification.

[0144] Flexible breathing tube Figures 7A–7B and 8A–8E illustrate various embodiments of flexible breathing tubes. Flexible tubes can be used to improve the ease of positioning and use of the tube when providing respiratory therapy to patients, especially neonatal patients. When using lightweight flexible tubes in a respiratory humidification system, the tube may vibrate and displace when certain respiratory waveforms are transmitted through the breathing tube, for example, when performing high-frequency vibrational ventilation. In some cases, vibration can cause significant displacement of the breathing tube, which can cause discomfort and anxiety to the patient's caregivers, such as prescribing physicians, nurses, therapists, or friends and family. Furthermore, tubes with higher rigidity may be more difficult to position properly, and a force load that may be uncomfortable for the patient or even cause injury may be applied to the patient interface. The embodiments described with respect to Figures 7A–7B and 8A–8E provide various solutions for damping and controlling vibration and displacement of the breathing tube in operation.

[0145] Referring to Figures 7A-7B and 8A-8D, the breathing tube has a first segment 402a and a second segment 402b, with an intermediate connector 414 located between the first segment 402a and the second segment 402b. The first segment 402a may include a humidifier interface connector 404 having a humidifier chamber at one end and a suitable fitting at the other end for connecting to the intermediate connector 414. The second segment 402b may have a patient interface connector 406 having a patient interface at one end and a suitable fitting at the other end for connecting to the intermediate connector 414. The segments of tubes 402a and 402b can be connected to each other by the intermediate connector to form a single conduit for gas delivery. The first segment 402a, the second segment 402b, and the intermediate connector 414 can be configured according to various embodiments disclosed herein. For example, segments 402a and 402b can be implemented according to segments 202a and 202b, respectively, and the intermediate connector 414 can be implemented according to the intermediate connector 214.

[0146] The second segment 402b can be shorter than the first segment 402a, and in certain implementations, the second segment 402b may be about half the length of the first segment 402a. The first segment 402a can have a length of, for example, at least about 0.5m and / or about 2m or less, at least about 0.7m and / or about 1.8m or less, at least about 0.9m and / or about 1.5m or less, or at least about 1m and / or about 1.2m or less. The second segment 402b can have a length of, for example, at least about 0.2m and / or about 1.5m or less, at least about 0.3m and / or about 1m or less, at least about 0.4m and / or about 0.8m or less, or at least about 0.5m and / or about 0.7m or less.

[0147] Referring to Figures 7A and 7B, embodiments of the breathing tube 410 are shown. The first segment 402a and the second segment 402b of the breathing tube 410 have different flexibility. The first segment 402a has higher stiffness or rigidity than the second segment 402b. The second segment 402b, closer to the patient interface, has higher flexibility than the first segment 402a. In some embodiments, the first segment and / or the second segment may have variable stiffness, as described with respect to Figures 6A-6C. For example, the first segment 402a may have constant stiffness, and the second segment 402b may have variable stiffness along the length of the segment, thereby the portion of the second segment 402b closest to the patient interface having the greatest flexibility. By including a segment 402a with higher stiffness, vibration and displacement can be reduced and damped in the larger segments of the tube. The relative flexibility of the first segment 402a and the second segment 402b can be controlled by changing the structure of the tube. In some embodiments, the segments 402a and 402b of the tube may be a composite tube, and the flexibility can be varied as discussed herein with respect to Figures 5A to 5E. For example, a second segment 402b with higher flexibility may have at least one of thinner sidewalls, a smaller inner diameter, a narrower pitch, and / or a smaller bead width compared to a first segment 402a with higher stiffness. In some embodiments, the first elongated member of the second segment 402b (e.g., reference no. 1203) is thinner and taller than the first elongated member of the first segment 402a.

[0148] Furthermore, the first segment 402a and the second segment 402b may be made of different materials. This may result in the first segment 402a and the second segment 402b having different stiffness / flexibility. Alternatively, different materials may be selected so that the first segment 402a and the second segment 402b have similar stiffness / flexibility. In one exemplary embodiment, the different materials are the same material having different durometers and / or viscosities. In another exemplary embodiment, the different materials are materials of different families, classes, or types.

[0149] In another exemplary embodiment, one or more segments may undergo post-treatment to make the segments more or less flexible. For example, one or more segments may undergo crosslinking after extrusion. In a further exemplary embodiment, the crosslinking agent may be externally cured (i.e., cured on the outer surface of the tube) but left uncured on the inner surface of the tube. Alternatively, the reverse may be performed, where the inner surface of the tube is cured but the outer surface is not. In a further exemplary embodiment, one or more segments of a multi-segmented tube may undergo such post-treatment, but the other segments of the multi-segmented tube may not.

[0150] Figures 8A–8E show embodiments of a breathing tube 420 with a sheath 408 covering one or more segments of the tube 420. The first segment 402a and the second segment 402b may have the same flexibility. The sheath 408 may be similar to the sheath 327 described with respect to Figure 6C. The sheath 408 may partially or completely enclose the outer walls of the segments and / or connectors of the tube 420. The sheath 408 may be applied around the wall as an extruded outer layer, as wrapping around the wall, or as a sleeve that slides or is pulled into position around the wall. The sheath 408 may be of any required thickness, but the thickness and material used should be balanced with the requirements for maintaining the flexibility of the tube. The sheath may be formed from a mesh, braid, or cloth cover. The sheath 408 can be fixed at one or more locations along the tube, or it can be fixed only at the ends of the tube segments, such as intermediate connectors, patient interfaces, and / or humidifier interfaces.

[0151] Mesh or braided sheaths may contain a considerable number of openings between the threads, and these openings are open to the surrounding environment. It should be understood that if these openings are large, the mesh or braided sheath will not function as a significant insulating layer. However, surprisingly, the applicant has found that mesh or braided sheaths act to dampen or absorb the displacement or movement of the tube during therapy, reducing the amount of displacement or movement to a level that is normal and acceptable to the caregiver. Furthermore, the applicant has found that such mesh or braided sheaths do not inhibit or restrict the flexibility of the tube.

[0152] In Figure 8A, the sheath is placed over the first segment 402a of the tube 420. In Figure 8C, the first sheath 408a is placed over the first segment 402a of the tube, and the second sheath 408b is placed over the second segment 402b. In another exemplary embodiment similar to Figure 8C, the sheath may be continuous along the entire length of the tube and pass under the intermediate connector. In Figure 8D, the first sheath segment 408a is placed over the first segment 402a of the tube, the second sheath segment 408b is placed over the second segment 402b, and the third sheath segment 408c is placed over the intermediate connector 414. The sheath segments 408a-408c may be a single sheath extending from the humidifier interface connector 404 to the patient interface connector 406. In some embodiments, the sheath may be divided into two or more sheaths. Figure 8E shows an embodiment of tube 430 that includes only a single flexible tube segment between the humidifier interface connector 404 and the patient interface connector 406. Tube 430 has a sheath 408 that extends along the entire length of the tube. In one exemplary embodiment, the sheath is a thin-walled sheath.

[0153] From Figures 7 and 8, it should be understood that, based on this disclosure, all combinations of flexibility, multiple or single segments, and sheaths can be used. Similarly, composite (or bubble) tubes may have higher or lower flexibility due to any of the modifications described with reference to Figure 5. For example, a segmented tube with an intermediate connector may have the same flexibility between segments. This tube may be more flexible than other tubes because the sidewalls near the lumen of the tube in the first member having a hollow body are thinner than the sidewalls exposed to the atmosphere, or it may be more flexible than other tubes based on other parameters described with reference to Figure 5. This tube may have a sheath over one or all segments, and the sheath may pass over or under the intermediate connector. Alternatively, the tube may be a single-segment tube having constant flexibility along its length, as shown in Figure 8E. This tube includes a sheath along its entire length. In another embodiment, the tube in Figure 8E includes a sheath over only a portion of the length of the tube. In another embodiment, the single tube in Figure 8E may have variable flexibility along its length, as shown in Figure 6. Alternatively, the tube may have different segments having different or the same flexibility. For example, the patient end segment may have higher, lower, or the same flexibility as the humidifier end segment. Similarly, if there are three or more segments, each segment may have higher, lower, or the same flexibility as the other segments of the tube.

[0154] Several examples of respiratory humidification systems and methods comprising related components have been described with reference to the figures. These figures illustrate various systems and modules, as well as the connections between them. The various modules and systems can be combined in various configurations, and the connections between the various modules and systems can represent physical or logical links. The representations in these figures are presented to clearly illustrate the principles. Details regarding the division of modules or systems are provided for the sake of clarity, not to define individual physical embodiments. The examples and figures are intended to illustrate, and not to limit, the scope of the inventions described herein. For example, the principles described herein can be applied to respiratory humidifiers and other types of humidification systems, including surgical humidifiers. The principles described herein can be applied to respiratory applications and also to other scenarios in which the temperature of a gas is controlled along multiple segments exposed to different ambient temperatures.

[0155] As used herein, the term “processor” broadly refers to any suitable combination of devices, logic blocks, modules, circuits, or elements for executing instructions. For example, the control device 122 may include any conventional general-purpose single-chip or multi-chip microprocessor, such as a Pentium® processor, MIPS® processor, PowerPC® processor, AMD® processor, ARM® processor, or ALPHA® processor. Furthermore, the control device 122 may include any conventional dedicated microprocessor, such as a digital signal processing unit or microcontroller. Various exemplary logic blocks, modules, and circuits described in relation to the embodiments disclosed herein may be implemented or carried out using general-purpose processing units, digital signal processing units (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gates or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein, or they may be pure software within a main processor. For example, logic module 504 may be a software-implemented functional block that does not utilize additional and / or special hardware elements. The control device 122 can be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a combination of a microcontroller and a microprocessor, multiple microprocessors, one or more microprocessors associated with a DSP core, or any other such configuration.

[0156] A data storage device can represent electronic circuitry that enables a processing unit to store and retrieve data. A data storage device can also represent an external device or system, such as a disk drive or solid-state drive. A data storage device can also represent a high-speed semiconductor storage device (chip), such as random-access memory (RAM) or various forms of read-only memory (ROM), which are directly connected to a communication bus or the control unit 122. Other types of data storage devices include bubble memory and core memory. A data storage device may be physical hardware configured to store data on a non-temporary medium.

[0157] While this specification discloses specific embodiments and examples, the subject matter of the invention extends beyond the particularly disclosed embodiments to other alternative embodiments and / or uses, as well as their modifications and equivalents. Therefore, the scope of the claims or embodiments appended herein is not limited by any of the specific embodiments described herein. For example, in any method or process disclosed herein, the actions or operations of the method or process may be performed in any suitable order and are not necessarily limited to any specific disclosed order. Various operations may be described sequentially as a number of separate operations to help understand a particular embodiment. However, the order of description should not be interpreted as suggesting that these operations are ordered. Furthermore, the structures described herein may be embodied as integrated components or as individual components. Specific aspects and advantages of these embodiments are described for comparison of the various embodiments. Not all such aspects or advantages are necessarily realized by any particular embodiment. Therefore, various embodiments can be implemented, for example, to realize or optimize one of the advantages or combinations of advantages taught herein, without necessarily realizing other embodiments or advantages that may also be taught or suggested herein.

[0158] Hypothetical expressions used herein, such as in particular “can,” “may,” and “for example,” are generally intended to indicate that certain features, elements, and / or conditions are included in certain embodiments and not in other embodiments, unless otherwise specified or consistent with the context in which they are used. Therefore, such hypothetical expressions are generally not intended to suggest that features, elements, and / or conditions are essential to one or more embodiments. When used herein, the terms “equip,” “include,” “have,” or any other conjugations thereof are intended to encompass non-exclusive inclusion. For example, a process, method, article, or apparatus that includes an enumeration of elements is not necessarily limited to those elements alone, but may include other elements not explicitly enumerated, or other elements specific to such process, method, article, or apparatus. Furthermore, the term “or” is used in its inclusive sense (rather than its exclusive sense), and therefore, when used to connect an enumeration of elements, for example, the term “or” means one, some, or all of the elements in that enumeration. Disjunctive expressions such as "at least one of X, Y, and Z" generally indicate that an element or term may be X, Y, or Z, unless otherwise specified or inconsistent with the context in which it is used. Therefore, such disjunctive expressions are not intended to suggest that, in a particular embodiment, at least one of X, at least one of Y, and at least one of Z must each be present. As used herein, the words "about" or "approximately" may mean that a certain value is within ±10%, ±5%, or ±1% of a specified value.

[0159] The methods and processes described herein may be embodied within software code modules executed by one or more general-purpose and / or dedicated computers, and may be partially or fully automated by such software code modules. The term “module” represents logic embodied in hardware and / or software, or a set of software instructions, which may have entry and exit points, written in a programming language such as C or C++. Software modules may be compiled and linked into executable programs installed in dynamically linked libraries, or they may be written in interpretive programming languages ​​such as BASIC, Perl, or Python. It should be understood that software modules may be callable from other modules or from themselves, and / or may be called in response to detected events or interruptions. Software instructions may be embedded in firmware, such as erasable programmable read-only memory (EPROM). Hardware modules may include connected logic units such as gates and flip-flops, and / or programmable units, such as programmable gate arrays, application-specific integrated circuits, and / or processing units. The modules described herein may be implemented as software modules, but may also be represented in hardware and / or firmware. Furthermore, in some embodiments, modules may be compiled individually, while in other embodiments, modules may represent a subset of instructions from an individually compiled program and may not have an interface available to other logic program units.

[0160] In certain embodiments, code modules may be implemented and / or stored in any type of computer-readable medium or other computer storage device. In some systems, data (and / or metadata) input to the system, data generated by the system, and / or data used by the system may be stored in any type of computer data repository, such as relational databases and / or flat file systems. Any of the systems, methods, and processes described herein may include interfaces configured to enable interaction with users, operators, other systems, components, programs, etc.

[0161] It should be emphasized that many changes and modifications can be made to the embodiments described herein, and that such elements should be understood to be included in other acceptable embodiments. All such modifications and variations are intended to be included within the scope of this disclosure and protected by the appended claims. Furthermore, nothing in the foregoing disclosure is intended to suggest that any particular component, feature, or process step is essential or indispensable.

Claims

1. It is a breathing tube, A first flexible tubular segment, A second tubular segment having second flexibility, wherein the second tubular segment is shorter than the first tubular segment, An intermediate connector connecting the first segment to the second segment, A braided mesh covering the first segment and surrounding the outer wall of the first segment, configured to dampen the displacement of the tubular first segment during high-frequency vibration ventilation flow through the breathing tube, The braided mesh comprises a plurality of filaments wound spirally clockwise around the outer wall of the tubular first segment and a plurality of filaments wound spirally counterclockwise around the outer wall of the tubular first segment, and the intermediate connector secures the braided mesh, the breathing tube.

2. The respiratory tube according to claim 1, wherein the second flexibility is the same as the first flexibility.

3. The respiratory tube according to claim 1, wherein the second flexibility is different from the first flexibility.

4. The breathing tube according to any one of claims 1 to 3, wherein the intermediate connector secures at least one end of the braided mesh.

5. The breathing tube according to claim 1, wherein the braided mesh extends along at least a partial length or substantially along the entire length of the first segment.

6. The breathing tube according to claim 1, wherein the first segment is a composite tube having a first elongated member having a hollow body spirally wound to form at least a portion of the breathing tube, and 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 breathing tube.

7. The first segment of the breathing tube is the humidifier end segment, The breathing tube according to claim 1, wherein the second segment is the patient interface end segment of the breathing tube.

8. The breathing tube according to claim 1, wherein the braided mesh is configured to attenuate the displacement of the tube by limiting wave propagation, vibration, or displacement during high-frequency vibration ventilation, or by resisting wave propagation, vibration, or displacement.

9. The breathing tube according to claim 1, wherein the braided mesh is fixed at a position along the outer wall of the first segment, or fixed only to the end of the first segment.

10. The breathing tube according to claim 9, wherein the braided mesh is fixed around or below the end connector or the intermediate connector by adhesive, friction fitting, or overmolding.

11. The breathing tube according to claim 1, wherein the first segment and the second segment are permanently joined to each other.

12. The breathing tube according to claim 1, wherein the second segment is part of the inspiratory limb located inside the incubator.

13. The breathing tube according to claim 1, wherein the braided mesh has 10 to 1,000 picks per meter, or 200 to 400 picks per meter.

14. The breathing tube according to claim 1, wherein the diameter of each filament is 0.25 mm to 0.28 mm.

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