Zone heating for respiratory circuit

Abstract

To provide heating of gas in a respiratory circuit for use with a humidification system.SOLUTION: An inspiratory limb 202 for a respiratory circuit includes: a first section 202a comprising a first heater wire circuit and a second section 202b comprising a second heater wire circuit. The inspiratory limb includes an intermediate connector 214 that includes a connection circuit that electrically couples a first heater wire circuit 206a to a second heater wire circuit 206b. The inspiratory limb can be configured to operate in two modes. In a first mode, electrical power passes through a first electrical connection line to provide the power to the first heater wire circuit without providing the power to the second heater wire circuit. In a second mode, electrical power passes through the first electrical connection line to provide the power to both the first heater wire circuit and the second heater wire circuit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] Incorporation by Reference This application is a continuation of U.S. Provisional Patent Application No. 61 / 726,532, filed November 14, 2012, entitled "ZONE HEATING FOR RESPIRATORY CIRCUITS"; U.S. Provisional Patent Application No. 61 / 786,141, filed March 14, 2013, entitled "ZONE HEATING FOR RESPIRATORY CIRCUITS"; U.S. Provisional Patent Application No. 61 / 877,736, filed September 13, 2013, entitled "ZONE HEATING FOR RESPIRATORY CIRCUITS"; U.S. Provisional Patent Application No. 61 / 877,784, filed September 13, 2013, entitled "CONNECTIONS FOR HUMIDICATION SYSTEM"; U.S. Provisional Patent Application No. 61 / 877,784, filed September 13, 2013, entitled "MEDICAL TUBES AND METHODS OF No. 61 / 877,622, entitled "HUMIDIFICATION SYSTEM," filed on Sep. 13, 2013; and U.S. Provisional Patent Application No. 61 / 877,566, entitled "HUMIDIFICATION SYSTEM," filed on Sep. 13, 2013. Each of the above-referenced patent applications is incorporated herein by reference in its entirety.

[0002] Additionally, PCT Application No. PCT / IB2012 / 001786, filed May 30, 2012, and entitled "MEDICAL TUBES AND METHODS OF MANUFACTURE," is hereby incorporated by reference in its entirety.

[0003] The present disclosure relates generally to humidification systems for providing humidified gas to a user, and more particularly to heating gas in a breathing circuit for use with a humidification system. [Background technology]

[0004] Many gas humidification systems deliver heated and humidified gases for various medical procedures, including respiratory therapy, laparoscopy, and the like. These systems can be configured to control temperature, humidity, and flow rate using feedback from sensors. To maintain desired characteristics during delivery to the user, the breathing circuit can have a heater associated with the gas line, where the heater provides heat to the gas as it flows to and / or from the user. The line heater can be controlled to provide heat to the gas so that it arrives at the user with desired characteristics, such as temperature and / or humidity. The humidification system can include a temperature sensor and provide feedback to a humidification controller, which can adjust and / or modify the power sent to the line heater to achieve a target temperature at a location along the associated line. Summary of the Invention [Means for solving the problem]

[0005] The systems, methods, and devices described herein have innovative aspects, none of which are essential or solely responsible for their desirable attributes. Without limiting the scope of the claims, some of the advantageous features are summarized below.

[0006] Some embodiments provide an inspiratory limb for a breathing circuit. The inspiratory limb described herein is particularly useful in situations where heated and humidified gas must pass through two different environments. This can be problematic, for example, in an infant incubator, where the temperature is significantly higher than the surrounding environment or where a portion of the ductwork delivering gas to the patient is under a blanket. However, the embodiments disclosed herein can be used in any environment where heated and / or humidified gas is delivered to a patient and are not limited to applications where the inspiratory limb passes through two different environments.

[0007] The inspiratory limb can include a first section of the inspiratory limb comprising a first structure forming a conduit configured to transport the humidified gas, the first section of the inspiratory limb comprising a first heater wire circuit. The inspiratory limb can include a second section of the inspiratory limb comprising a second structure forming a conduit configured to transport the humidified gas, the second structure configured to mechanically couple to the first structure of the first section to form an extended conduit for the humidified gas, the second section of the inspiratory limb comprising a second heater wire circuit. The inspiratory limb can include an intermediate connector including a connection circuit electrically coupling the first heater wire circuit to the second heater wire circuit, the intermediate connector can be coupled to a patient end of the first section of the inspiratory limb and a chamber end of the second section of the inspiratory limb to form a single conduit for the humidified gas. The intermediate connector may be covered by a portion of the first segment of the inspiratory limb, a portion of the second segment of the inspiratory limb, or a portion of both the first and second segments of the inspiratory limb such that the intermediate connector is internal to the inspiratory limb.

[0008] The inspiratory limb can be configured to operate in two heating modes. In a first heating mode, power passes through the intermediate connector to provide power to the first heater wire circuit and not to the second heater wire circuit. In a second heating mode, power passes through the intermediate connector to provide power to both the first heater wire circuit and the second heater wire circuit. For example, the intermediate connector can include electrical components configured to route power along different paths based at least in part on a direction of current and / or a polarity of voltage. The intermediate connector can include a conductive track, which can provide a short circuit (e.g., a direct electrical connection without an intervening electrical component) between one or more wires in the first heater wire circuit and one or more wires in the second heater wire circuit. The intermediate connector can include a conductive track, which can electrically couple one or more wires in the first heater wire circuit to one or more wires in the second heater wire circuit, where the conductive track includes electrical components such as, for example, but not limited to, diodes, transistors, capacitors, resistors, logic gates, integrated circuits, etc. In certain embodiments, the intermediate connector includes a diode electrically coupled to both the first heater wire circuit and the second heater wire circuit. In certain embodiments, the inspiratory limb can further include a first sensor circuit having a first sensor positioned at the intermediate connector. In certain embodiments, the inspiratory limb can further include a second sensor circuit having a second sensor positioned at the patient-end connector, the patient-end connector being positioned at a patient-end of the second section of the inspiratory limb. The inspiratory limb can be configured to operate in two sensing modes. In the first sensing mode, a signal from the first sensor is received and a signal from the second sensor is not received. In the second sensing mode, a signal from the second sensor is received and a signal from the first sensor is not received. In some embodiments, the sensing includes receiving signals in parallel from both the first sensor and the second sensor.In such an embodiment, the algorithm may determine a parameter measured by the first sensor based at least in part on signals received in parallel from both the first sensor and the second sensor. In certain embodiments, the intermediate connector includes a diode electrically coupled to both the first sensor circuit and the second sensor circuit. The patient-end connector may be configured to provide an electrical connection for the second sensor circuit. Similarly, the patient-end connector may also be configured to provide an electrical connection for the second heater wire circuit. The sensor may be a temperature sensor, a humidity sensor, a flow sensor, or the like. The first and second sensors may be sensors configured to measure one or more parameters, such as temperature, humidity, flow, oxygen content, or the like. In some embodiments, the first and second sensors are configured to measure at least one similar parameter (e.g., temperature, humidity, flow, or the like). In some embodiments, three or more sensors may be included and may be positioned in the intermediate connector and / or the patient-end connector.

[0009] Some embodiments provide a respiratory humidification system comprising an inspiratory limb and a controller. The inspiratory limb may include a first segment having a first heater wire circuit, a second segment having a second heater wire circuit, an intermediate connector having a connector circuit configured to electrically couple the first heater wire circuit to the second heater wire circuit, a first sensor positioned at a patient end of the first segment, and a second sensor positioned at a patient end of the second segment. The controller may be adapted to selectively switch between a first mode and a second mode, where in the first mode the controller provides power to the first heater wire circuit through the connector circuit and in the second mode the controller provides power to the first and second heater wire circuits. In certain embodiments, the respiratory humidification system switches modes based at least in part on input from one or both sensors. In certain embodiments, the switching is based at least in part on parameters including one or more of temperature, flow rate, humidity, power, or any combination thereof. The parameters may be derived or obtained directly from the first sensor, the second sensor, or a combination of both sensors. In certain embodiments, the first and second modes are defined by the direction of current or polarity of voltage provided by the power source. In some embodiments, the respiratory humidification system may include three or more sensors, which provide inputs used to control the heating of the inspiratory limb.

[0010] Some embodiments provide a dual limb circuit that can include an inspiratory limb. Such an inspiratory limb can include a first segment having a first heater wire circuit, a second segment of the inspiratory limb having a second heater wire circuit, an intermediate connector having a connector circuit configured to electrically couple the first heater wire circuit to the second heater wire circuit, a first sensor positioned at a patient end of the first segment, and a second sensor positioned at a patient end of the second segment. The dual limb circuit can also include an expiratory limb with an expiratory heater wire circuit. The dual limb system can further include an interface connected to the inspiratory limb and the expiratory limb. The dual limb system can further include a controller adapted to selectively switch between a first mode and a second mode, where in the first mode the controller provides power to the first heater wire circuit through the connector circuit and in the second mode the controller provides power to the first and second heater wire circuits. In certain embodiments, the heating of the expiratory limb is performed using an expiratory heater wire circuit separate from the heating of the inspiratory limb using the first and second heater wire circuits. In certain embodiments, the expiratory limb is powered in parallel with the first heater wire circuit in the first section of the inspiratory limb and / or in parallel with the first and second heater wire circuits. In certain embodiments, the expiratory limb can be designed to be powered in only the first mode, only the second mode, or in both the first and second modes. In certain embodiments, the interfaces are connected by a Y-piece. Any suitable patient interface can be incorporated. Patient interface is a broad term and should be interpreted in its ordinary and customary sense to those skilled in the art (i.e., should not be limited to a special or specialized sense), including, but not limited to, masks (such as tracheal masks, face masks, and nasal masks), cannulas, and nasal pillows.

[0011] In some embodiments, a segmented inspiratory limb is provided, where the segment structure comprises an elongated tube. The elongated tube can include a first elongated member having a hollow body helically wound to at least partially form a conduit having a longitudinal axis, a lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen. The elongated tube can include a second elongated member helically wound and joined between adjacent turns of the first elongated member, the second elongated member forming at least a portion of the lumen of the elongated tube. In certain implementations, the first elongated member forms a plurality of bubbles in the lumen having a flattened surface in a longitudinal cross section. In certain implementations, adjacent bubbles are separated by a gap above the second elongated member. In certain implementations, adjacent bubbles are not directly connected to each other. In certain implementations, the plurality of bubbles have perforations.

[0012] Reference numbers may be repeated throughout the drawings to indicate a general correspondence between referenced elements. The drawings are provided to illustrate example embodiments described herein and are not intended to limit the scope of the present disclosure. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 illustrates an exemplary respiratory humidification system for delivering humidified gas to a user, the respiratory humidification system having a breathing circuit that includes a segmented inspiratory limb having a sensor within each segment. [Diagram 2] FIG. 1 illustrates a segmented inspiratory limb for use with a humidification system having an intermediate connector configured to join heater wires and sensors in the two segments. [Figure 3A] FIG. 1 is an exemplary circuit diagram including an active rectifier power supply for providing power to heater wires in a segmented inspiratory limb of a breathing circuit, the circuit being configured to power the heater wires in a first segment of the inspiratory limb in a first mode and to power the heater wires in both segments in a second mode. [Figure 3B]FIG. 1 is an exemplary circuit diagram including an active rectifier power supply for providing power to heater wires in a segmented inspiratory limb of a breathing circuit, the circuit being configured to power the heater wires in a first segment of the inspiratory limb in a first mode and to power the heater wires in both segments in a second mode. [Figure 4A] FIG. 1 illustrates an exemplary humidification system having an inspiratory limb and an expiratory limb, the humidification system configured to control heater wires in both limbs. [Figure 4B] FIG. 1 illustrates an exemplary humidification system having an inspiratory limb and an expiratory limb, the humidification system configured to control heater wires in both limbs. [Figure 4C] FIG. 1 illustrates an exemplary humidification system having an inspiratory limb and an expiratory limb, the humidification system configured to control heater wires in both limbs. [Figure 4D] FIG. 1 illustrates an exemplary humidification system having an inspiratory limb and an expiratory limb, the humidification system configured to control heater wires in both limbs. [Diagram 5] FIG. 1 is a block diagram of an exemplary system configured to detect the presence of an inspiratory limb extension and provide power to heater wires in the inspiratory limb, the inspiratory limb extension, and the expiratory limb. [Figure 6A] FIG. 2 illustrates an exemplary circuit diagram in a humidification system, where the circuit is configured to read data from two sensors. [Figure 6B] FIG. 2 illustrates an exemplary circuit diagram in a humidification system, where the circuit is configured to read data from two sensors. [Figure 7] FIG. 1 is an exemplary circuit diagram in a humidification system, where the circuit is configured to read temperature data using two transistors. [Figure 8A] FIG. 1 is an example diagram of a hardware configuration for a breathing circuit with an inspiratory limb and an expiratory limb, the inspiratory limb having a first section and a second section. [Figure 8B]FIG. 1 is an example diagram of a hardware configuration for a breathing circuit with an inspiratory limb and an expiratory limb, the inspiratory limb having a first section and a second section. [Figure 9] FIG. 13 shows an exemplary embodiment of a respiratory humidification system that utilizes a microcontroller in the intermediate connector to measure data for controlling heating and reading sensor values ​​at the inspiratory limb. [Figure 10] FIG. 13 is a block diagram of an intermediate connector for the inspiratory limb, the intermediate connector using a microcontroller. [Figure 11] FIG. 11 is a circuit diagram for an exemplary power module and data line converter included in the intermediate connector shown in FIG. [Figure 12] FIG. 11 is a circuit diagram of an exemplary dual optocoupler circuit used with the intermediate connector shown in FIG. 10 to provide bidirectional data communication between the control side and AC side on a circuit board. [Figure 13] FIG. 1 is a circuit diagram of an exemplary humidification system incorporating a digital temperature sensor for use with a breathing circuit having an inspiratory limb with at least two sections. [Figure 14A] FIG. 1 illustrates an exemplary printed circuit board ("PCB") of an intermediate connector. [Figure 14B] FIG. 1 illustrates an exemplary printed circuit board ("PCB") of an intermediate connector. [Figure 14C] 1 illustrates an exemplary embodiment of an intermediate connector. [Figure 14D] 1 illustrates an exemplary embodiment of an intermediate connector. [Figure 15A] FIG. 1 illustrates an exemplary PCB for a patient-end connector. [Figure 15B] 1 illustrates an exemplary embodiment of a patient end connector. [Figure 15C] 1 illustrates an exemplary embodiment of a patient end connector. [Figure 15D] 1 illustrates an exemplary embodiment of a patient end connector. [Figure 15E] 1 illustrates an exemplary embodiment of a patient end connector. [Figure 16A] FIG. 13 illustrates an exemplary embodiment of a placement limiter for a segmented inspiratory limb. [Figure 16B] FIG. 13 illustrates an exemplary embodiment of a placement limiter for a segmented inspiratory limb. [Figure 16C] FIG. 13 illustrates an exemplary embodiment of a placement limiter for a segmented inspiratory limb. [Figure 16D] FIG. 13 illustrates an exemplary embodiment of a placement limiter for a segmented inspiratory limb. [Figure 16E] FIG. 13 illustrates an exemplary embodiment of a placement limiter for a segmented inspiratory limb. [Figure 17A] FIG. 2 is a side view of a section of an exemplary composite pipe. [Figure 17B] 17B is a longitudinal cross-sectional view of the upper portion of a tube similar to the exemplary composite tube of FIG. 17A. [Figure 17C] FIG. 11 is another longitudinal cross-sectional view showing a first elongated member within a composite tube. [Figure 17D] FIG. 2 is another longitudinal cross-sectional view of the upper part of the tube. [Figure 17E] FIG. 2 is another longitudinal cross-sectional view of the upper part of the tube. [Figure 18A] FIG. 13 is a transverse cross-sectional view of a second elongated member within a composite tube. [Figure 18B] FIG. 11 is another transverse cross-sectional view of the second elongated member. [Figure 18C] FIG. 13 illustrates another exemplary second elongated member. [Figure 18D] FIG. 13 illustrates another exemplary second elongated member. [Figure 18E] FIG. 13 illustrates another exemplary second elongated member. [Figure 18F] FIG. 13 illustrates another exemplary second elongated member. [Figure 18G] FIG. 13 illustrates another exemplary second elongated member. [Figure 19A] 11A-11C illustrate examples of first elongated member shapes configured to improve thermal efficiency. [Figure 19B] 11A-11C illustrate examples of first elongated member shapes configured to improve thermal efficiency. [Figure 19C] 11A-11C illustrate examples of first elongated member shapes configured to improve thermal efficiency. [Figure 19D] FIG. 1 illustrates an example of a filament configuration configured to improve thermal efficiency. [Figure 19E] FIG. 1 illustrates an example of a filament configuration configured to improve thermal efficiency. [Figure 19F] FIG. 1 illustrates an example of a filament configuration configured to improve thermal efficiency. [Figure 20A] FIG. 2 is a diagram showing an example of a stack of first elongated members. [Figure 20B] FIG. 2 is a diagram showing an example of a stack of first elongated members. [Figure 20C] FIG. 2 is a diagram showing an example of a stack of first elongated members. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Specific embodiments and examples of segmented inspiratory limb and multi-zone heating are described herein. Those skilled in the art will understand that the present disclosure encompasses the specifically disclosed embodiments and / or uses, as well as obvious modifications and equivalents thereof. Therefore, it is not intended that the scope of the present disclosure disclosed herein be limited by any specific embodiments described herein.

[0015] Described herein are systems and methods for providing heat to a segmented inspiratory limb in a breathing circuit of a respiratory humidification system. While most of the description herein is in the context of a segmented inspiratory limb in a breathing circuit, it should be understood that one or more features of the present disclosure may also be implemented in other scenarios where it is desirable to provide differential heating within segmented gas delivery lines, for example in respiratory, surgical, or other applications.

[0016] The present disclosure refers to heater wires, heating elements, and / or heaters in the context of providing heat to a conduit. For example, heater wire is a broad term and should be interpreted in its ordinary and customary sense to one of ordinary skill in the art (i.e., not limited to a special or specialized sense), including, but not limited to, heater strips and / or heat transfer elements that generate heat when power is provided. Examples of such heating elements include wires formed from conductive metals (e.g., copper), conductive polymers, conductive inks printed on the surface of a conduit, conductive materials used to create tracks in a conduit, and the like. Additionally, the present disclosure refers to conduits, limbs, and medical tubing in the context of gas delivery. For example, tubing is a broad term and should be interpreted in its ordinary and customary sense to one of ordinary skill in the art, including, but not limited to, passages having various cross sections, such as cylindrical and non-cylindrical passages. Certain embodiments may incorporate composite tubing, which may be generally defined as a tube comprising two or more sections, or in particular, in some embodiments, two or more components, as described in more detail below. The segmented limbs with the disclosed medical tubing can also be used within breathing circuits, such as continuous, variable, or bi-level positive airway pressure (PAP) systems, or other forms of respiratory therapy. The terms "conduit" and "limb" should be construed as equivalent to tubing.

[0017] When a heated and humidified breathing tube is used for an incubator (or any area with a temperature change, such as around a radiant warmer used for a burn patient or under a blanket used by the patient), the breathing tube passes through at least two different zones: a cooler zone (such as an area outside the incubator) and a hotter zone (such as an area inside the incubator). If the tube is heated along its entire length, one of the zones will tend to be at an undesirable, inappropriate, or suboptimal temperature, depending on which zone is sensed (e.g., which zone contains a temperature sensor). If the heater wires are controlled to a sensor inside the incubator (such as a patient end temperature sensor), the section outside the incubator will tend to be too cold, which can result in condensation. Conversely, if the heater wires are controlled to a sensor outside the incubator, the section inside the incubator may be too hot, which can result in gas being delivered to the patient that is too hot. Thus, the present disclosure describes systems and methods that allow for control of heat in a segmented breathing tube. Here, each section has an associated sensor that provides feedback to the control module. Although some embodiments are described herein with respect to two sections, such systems may be expanded to accommodate applications with additional sections, sections, or regions. For example, in one embodiment with three temperature sections, a section of the breathing tube may be heated based at least in part on three different temperature sensors in the section. Additionally, embodiments disclosed herein may control heat delivered to the breathing tube based on parameters at the patient end, bypassing or ignoring one or more of the sensors at midpoints along the tube. Additionally, embodiments disclosed herein may control heat delivered to the breathing tube using parameters provided by sensors including, for example, but not limited to, temperature sensors, humidity sensors, flow sensors, oxygen sensors, and the like.

[0018] The control module can monitor and control the heating temperature in multiple zones 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 the entire breathing tube in a second mode using some embodiments of the connector assembly described herein. Some embodiments described herein can be used without flying leads, exposed connectors, and / or patient-end electrical connections. The term "flying leads" as used herein includes electrical connections that extend external to the breathing tube, electrical connections that extend internally through the breathing tube, and electrical connections that are incorporated, molded, or otherwise formed or included as part of the breathing tube. The control module can be located inside the humidifier or outside the humidifier. In some embodiments, a controller is located inside the humidifier to control heater wires associated with the first section of the inspiratory limb, the second section of the inspiratory limb, and the expiratory limb, and to read parameters from sensors associated with the first and second sections of the inspiratory limb and / or the expiratory limb.

[0019] The control module may also adaptively change temperatures associated with the segments. For example, the control module may monitor temperature sensors associated with one or more segments. The monitoring may be continuous, periodic, interrupt or event-based, or other manner. For example, the monitoring of the temperature sensors may be based on reading values ​​from an analog-to-digital converter, determining a voltage or current, sensing a logical condition, reading a thermostat device, measuring a thermistor value, measuring a resistance temperature detector, measuring a thermocouple voltage, or other methods for sensing temperature, such as, but not limited to, using a semiconductor junction sensor, an infrared or thermal radiation sensor, a thermometer, an indicator, etc. In some embodiments, the temperature sensor is a thermistor.

[0020] In some embodiments, the ratio of power delivered to the first segment of the inspiratory limb and the second segment of the inspiratory limb can be varied during use based at least in part on feedback from sensors associated with each segment. For example, the ratio of power can be varied such that each segment is heated to a temperature that reduces or prevents condensation. As a further example, the ratio of power can be varied such that too hot gas is not provided to the patient. In some embodiments, the ratio of power can be varied continuously based on feedback from sensors (e.g., temperature sensors, humidity sensors, oxygen sensors, flow sensors, etc.). The ratio of power can be varied in a variety of ways. For example, the ratio of power can be varied by changing the amplitude (including but not limited to voltage and / or current) of the power signal, the duration of the power signal, or the duty cycle of the power signal, or by other suitable modifications to the power signal. In one embodiment, the ratio of power is varied by changing the magnitude of the current provided.

[0021] Some embodiments provide an inspiratory limb with heater wires that are not internal to the gas path, but rather are contained within a material that separates the heater wires from the gas path and insulates them from the external environment. In some embodiments, the circuitry used to provide power to the heater wires in a section and to read the sensors is internal to the inspiratory limb so that it is not exposed to the external environment. In some embodiments, the heater wires are molded into the inspiratory or expiratory tube such that the ends of the heater wires in the complementary section of the tube contact an intermediate connector such that the heater wires are electrically coupled to the intermediate connector, where the intermediate connector can be configured to provide circuitry for heater wire control and / or sensor reading. In some embodiments, the duty cycle of the power source applied to the heater wires can be modified or changed to vary the amount of heat delivered to the gas as it flows along the associated section.

[0022] Some embodiments described herein provide a respiratory humidification system configured to deliver warm humidified gas to a patient or other user. The gas is passed through a liquid chamber filled with liquid (e.g., water) that is heated using a heater plate. The liquid evaporates in the chamber and mixes with the gas flowing over it, thereby heating and / or humidifying the gas. The humidified gas can be delivered to an inspiratory limb having one or more heater wires associated therewith. The heater wires can be selectively powered to provide a predetermined, desired, suitable, or selected amount of heat to the humidified gas. In some embodiments, the respiratory humidification system can be used with an incubator or radiant warmer. The inspiratory limb can be segmented such that a first segment is external to the incubator and a second segment is internal to the incubator. Additionally, a first heater wire set can be associated with the first segment and a second heater wire set can be associated with the second segment. The humidification system can be configured to provide power to a first heater wire set in a first mode and to a second heater wire set in a second mode. In some embodiments, the humidification system can be configured to provide power to a first heater wire set in a first mode and to provide power to a second heater wire set in a second mode. The inspiratory limb can include a sensor at the end of each section to provide feedback to the humidification system, which is used in selecting power to deliver to the heater wire sets in the section. In some embodiments, the humidification system can include an expiratory limb having associated heater wires that are also selectively controlled by the humidification system. In this application, the segmented limb is described with reference to the inspiratory limb. However, the features described can also be applied to the expiratory limb.

[0023] Respiratory Humidification Systems 1 illustrates an exemplary respiratory humidification system 100 for delivering humidified gas to a user, the respiratory humidification system 100 having a breathing circuit 200 including a segmented inspiratory limb 202 having sensors 204a, 204b in each segment. The segmented inspiratory limb 202 may be used with an incubator 208 as shown, or may be used with another system, such as a radiant warmer, where there are different temperatures along various segments of the inspiratory limb 202. The segmented inspiratory limb 202 may be used to provide different levels of heat to 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.

[0024] The illustrated respiratory humidification system 100 includes a pressurized gas source 102. In some implementations, the pressurized gas source 102 includes a fan, blower, or the like. In some implementations, the pressurized gas source 102 includes a ventilator or other positive pressure generating device. The pressurized gas source 102 includes an inlet 104 and an outlet 106.

[0025] The pressurized gas source 102 provides a flow of fluid (e.g., oxygen, anesthetic gas, air, etc.) to the humidification unit 108. The fluid flow proceeds from an outlet 106 of the pressurized gas source 102 to an inlet 110 of the humidification unit 108. In the illustrated configuration, the humidification unit 108 is shown separate from the pressurized gas source 102, with the inlet 110 of the humidification unit 108 connected to the outlet 106 of the pressurized gas source 102 by a conduit 112. In some implementations, the pressurized gas source 102 and the humidification unit 108 may be integrated into a single housing.

[0026] Although other types of humidification units may be used to obtain certain features, aspects, and advantages described in this disclosure, the illustrated humidification unit 108 is a pass-over humidifier that includes a humidification chamber 114 and an inlet 110 to the humidification chamber 114. In some implementations, the humidification chamber 114 includes a body 116 to which a base 118 is attached. A compartment may be defined within the humidification chamber 116, the compartment adapted to hold a volume of liquid that may be heated by heat transferred or provided through the base 118. In some implementations, the base 118 is adapted to contact a heater plate 120. The heater plate 120 may be controlled by a controller 122 or other suitable component to vary and control the heat transferred into the liquid.

[0027] The controller 122 of the humidification unit 108 can control the operation of the various components of the respiratory humidification system 100. Although the illustrated system is shown as using a single controller 122, multiple controllers can be used in other configurations. The multiple controllers can communicate or can provide separate functions, and thus the controllers do not need to communicate. In some implementations, the controller 122 can comprise a microprocessor, processing unit, or logic circuitry with associated memory or storage media that includes software code for a computer program. In such implementations, the controller 122 can control the operation of the respiratory humidification system 100 according to instructions contained in, for example, a computer program, and also in response to internal or external inputs. The controller 122, or at least one of the multiple controllers, can be located with the breathing circuit, attached to the breathing circuit, or incorporated as part of the breathing circuit.

[0028] The body 116 of the humidification chamber 114 includes a port 124 that defines an inlet 110 of the humidification chamber 114, and a port 126 that defines an outlet 128. When a liquid contained within the humidification chamber 114 is heated, liquid vapor is mixed with gas introduced into the humidification chamber 114 through the inlet port 124. The gas and vapor mixture exits the humidification chamber 114 through the outlet port 126.

[0029] The respiratory humidification system 100 includes a breathing circuit 200 with an inspiratory limb 202 connected to an outlet 128 that defines an outlet port 126 of the humidification unit 108. The inspiratory limb 202 carries the mixture of gas and water vapor exiting the humidification chamber 114 toward the user. The inspiratory limb 202 can include a heating element 206 positioned along the inspiratory limb 202 that is configured to reduce condensation along the inspiratory limb 202 to control the temperature of the gas reaching the user, maintain the humidity of the gas, or any combination thereof. The heating element 206 can increase or maintain the temperature of the mixture of gas and water vapor carried by the inspiratory limb 202. In some implementations, the heating element 206 can be a wire that defines a resistive heater. By increasing or maintaining the temperature of the mixture of gas and water vapor exiting the humidification chamber 114, water vapor is less likely to condense from the mixture.

[0030] The respiratory humidification system 100 may be used with an incubator 208. The incubator 208 may be configured to maintain a desired environment for a user, such as a selected, predetermined, or desired temperature, inside the incubator 208. Thus, inside the incubator 208, the internal ambient temperature may be different than the temperature outside the incubator 208. Thus, the incubator 208 generates, defines, creates, or maintains zones of different temperatures 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 may create problems during delivery of gas to the user, such as condensation along the inspiratory limb 202, delivery of gas at too high a temperature, or both.

[0031] The respiratory humidification system 100 may include an expiratory limb 210 having an associated heating element 212. In some embodiments, the expiratory limb 210 and the inspiratory limb 202 may be connected using a suitable attachment (e.g., a Y-piece). In some embodiments, the respiratory humidification system 100 may be used with radiant warmers, under blankets, or other systems or situations that create two or more temperature zones. The systems and methods described herein may be used with such systems and are not limited to implementations incorporating incubators.

[0032] The inspiratory limb 202 can be divided into sections 202a and 202b, where the first section 202a can be the portion of the inspiratory limb 202 that is outside the incubator 208 and the second section 202b (e.g., an incubator extension) can be the portion of the inspiratory limb 202 that is inside the incubator 208. The first section 202a and the second section 202b can be of different lengths or the same length. In some embodiments, the second section 202b can be shorter than the first section 202a, and in certain implementations, the second section 202b can be about half the length of the first section 202a. The first section 202a can have a length of, for example, at least about 0.5 m and / or no more than about 2 m, at least about 0.7 m and / or no more than about 1.8 m, at least about 0.9 m and / or no more than about 1.5 m, or at least about 1 m and / or no more than about 1.2 m. The second section 202b can have a length of, for example, at least about 0.2 m and / or no more than about 1.5 m, at least about 0.3 m and / or no more than about 1 m, at least about 0.4 m and / or no more than about 0.8 m, or at least about 0.5 m and / or no more than about 0.7 m.

[0033] The inspiratory limb sections 202a, 202b can be coupled together to form a single gas delivery conduit. In some embodiments, the first section 202a can include one or more first heater wires 206a and one or more first sensors 204a, and can be used without the second section 202b. The controller 122 can be configured to control the first heater wires 206a and read the first sensor 204a even when the second section 202b is not coupled to the first section 202a. Additionally, when the second section 202b is coupled to the first section 202a, the controller 122 can be configured to control the first and second heater wires 206a, 206b in the respective sections and read the first and second sensors 204a, 204b. In some embodiments, the controller 122 can be configured to control the respective first and second heater wires 206a, 206b and read the respective first and second sensors 204a, 204b when the second section 202b is attached, and can be configured to control the first heater wire 206a and read the first sensor 204a when the second section 202b is not attached, without requiring modification of the controller 122 or the humidification unit 108. Thus, the same controller 122 and / or humidification unit 108 can be used regardless of whether the inspiratory limb 202 includes both the first and second sections 202a and 202b, or only the first section 202a. In some embodiments, the controller 122 can be further configured to control the heater wires 212 in the expiratory limb 210 without modification of the controller 122 or the humidification unit 108. Thus, the respiratory humidification system 100 can be operated with or without the second section 202b attached, and / or with or without the expiratory limb 210 attached.

[0034] In some embodiments, the first section 202a and the second section 202b are permanently joined together to form a single gas delivery conduit. As used herein, "permanently joined" means that the sections 202a, 202b are joined together such that it is difficult to separate them, for example, by using adhesives, friction fits, overmolding, mechanical connectors, etc. In some embodiments, the first section 202a and the second section 202b are configured to be releasably coupled. For example, the first section 202a can be used for gas delivery without the second section 202b, or the first section 202a and the second section 202b can be coupled together to form a single gas delivery conduit. In some embodiments, the first section 202a and the second section 202b can be configured to be coupled together in a unique configuration. For example, the first section 202a can have a predetermined chamber end (e.g., an end closest to the chamber 114 or the humidification unit 108 along the direction of flow of humidified gas to the patient) and a predetermined patient end (e.g., an end closest to the patient along the direction of flow of humidified gas to the patient), where the chamber end is configured to couple to components at the chamber 114 and / or the humidification unit 108. The second section 202b can have a predetermined chamber end and a predetermined patient end, where the chamber end is configured to couple only to the patient end of the first section 202a. The chamber end of the first section 202a can be configured not to couple to either end of the second section 202b. Similarly, the patient end of the first section 202a can be configured not to couple to the patient end of the second section 202b. Similarly, the patient end of the second section 202b can be configured not to couple to either end of the first section 202a. Thus, the first section 202a and the second section 202b can be configured to couple in only one direction to form a single gas delivery conduit. In some embodiments, the first section 202a and the second section 202b can be configured to couple in a variety of configurations.For example, the first and second segments 202a and 202b can be configured to not include a predetermined patient end and / or a predetermined chamber end. As another example, the first and second segments 202a and 202b can be configured such that the patient end and / or chamber end of the first segment 202a can be coupled to the chamber end or patient end of the second segment 202b. Similarly, the first and second segments 202a and 202b can be configured such that the chamber end and / or patient end of the second segment 202a can be coupled to the patient end or chamber end of the second segment 202b.

[0035] The respiratory humidification system 100 includes an intermediate connector 214 that can be configured to electrically couple elements of the first and second segments 202a and 202b of the inspiratory limb 202. The intermediate connector 214 can be configured to electrically couple the heater wires 206a of the first segment 202a to the heater wires 206b of the second segment 202b to enable control of the heater wires 206a, 206b with the controller 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 to enable the controller 122 to obtain the outputs of each of the sensors. The intermediate connector 214 can include electrical components that enable selective control of the heater wires 206a, 206b and / or selective reading of the sensors 204a, 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, 206b in a second mode. Electrical components included in the intermediate connector 214 may include, for example, but are not limited to, resistors, diodes, transistors, relays, rectifiers, switches, capacitors, inductors, integrated circuits, microcontrollers, microprocessors, RFID chips, wireless communication sensors, and the like. In some embodiments, the intermediate connector 214 may be configured within the inspiratory limb 202 such that it is substantially shielded from external elements (e.g., less than 1% of water, particulates, contaminants, and the like from the environment outside the inspiratory limb 202 contacts 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 humidified gases within the inspiratory limb 202 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 cost and / or increase reliability.

[0036] The inspiratory limb 202 may include sensors 204a, 204b in each section 202a, 202b of the inspiratory limb. The first sensor 204a may be positioned near the end of the first section 202a, near the incubator 208, such that a parameter derived from the first sensor 204a corresponds to a parameter of the humidified gas entering the second section 202b. The second sensor 204b may be positioned near the end of the second section 202b, such that a parameter derived from the second sensor 204b corresponds to a parameter of the humidified gas delivered to the patient or user. The output of the sensors 204a, 204b may be sent to the controller 122 as feedback for use in controlling the power delivered to the heating elements 206a, 206b of the inspiratory limb sections 202a, 202b. In some embodiments, one or both of the sensors 204a, 204b may be a temperature sensor, a humidity sensor, an oxygen sensor, a flow sensor, etc. The temperature sensor may be any suitable type of temperature sensor including, for example, without limitation, a thermistor, a thermocouple, a digital temperature sensor, a transistor, etc. Parameters provided by or derived from the sensor may include, for example, without limitation, temperature, humidity, oxygen content, flow rate, or any combination thereof, etc.

[0037] The controller 122 can be configured to control the heater wires 206a and 206b, receive feedback from the sensors 204a and 204b, provide logic for controlling power to the heater wires 206a and 206b, adjust control of the heater wires 206a and 206b in response to readings from the sensors 204a and 204b, detect the presence of the second segment 202b of the inspiratory limb 202, derive parameters from readings from the sensors 204a and 204b, and the like. In some embodiments, the controller 122 includes a power source configured to send power to the heater wires. The power source may be an AC or DC power source. In some embodiments, the controller 122 can receive input from a heater plate sensor 130. The heater plate sensor 130 can provide the controller 122 with information regarding the temperature and / or power usage of the heater plate 120. In some embodiments, the controller 122 can receive input from a flow sensor 132. Any suitable flow sensor 132 may be used, and the flow sensor 132 may 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 flow sensor 132 is positioned at the inlet port 124 of the humidification chamber 114.

[0038] Segmented inspiratory limb 2 illustrates a portion of a segmented inspiratory limb 202 for use with the 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 configured to couple a first heater wire 206a to a second heater wire 206b and a first sensor 204a to a second sensor 204b within segments 202a and 202b, respectively. Coupling 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 a user, where the mechanical coupling of segments 202a and 202b allows the respective heater wires 206a, 206b to be electrically coupled to the respective sensors 204a, 204b by the intermediate connector 214.

[0039] The segmented inspiratory limb 202 can comprise a structure 216 that forms a lumen through which the humidified gas can pass. The structure 216 can include a passage formed in a wall of the structure 216 configured to accommodate the heater wire 206a or 206b, such that the heater wire 206a or 206b is covered by an outer surface of the structure 216 so as to be shielded from and / or not exposed to the humidified gas traveling through the lumen. For example, the structure 216 can be a spiral bubble tube, and the heater wire passage is a coil molded within the tube. The structure 216 can comprise any type of suitable material, and can include insulating and / or flexible materials. In some embodiments, the structure 216 and intermediate connector 214 can be configured to wrap around the intermediate connector 214 such that the heater wires 206a and 206b are electrically coupled to the intermediate connector 214 when the first section 202a and the second section 202b are mechanically coupled. In some embodiments, the first section 202a and / or the intermediate connector 214 may eliminate flying leads for connecting to the second section 202b, thereby facilitating connection of the second section 202b to the first section 202a.

[0040] Structures 216 at the complementary ends of the first and second segments 202a, 202b can be configured to receive the intermediate connector 214. Thus, the intermediate connector 214 can be internal to the inspiratory limb 202. In some embodiments, the complementary ends of the first and second segments 202a, 202b can be configured to shield the intermediate connector 214 from the humidified gas traveling through the inspiratory limb 202. In some embodiments, the intermediate connector 214 is internal to the inspiratory limb 202 and shielded from the humidified gas in the duct, thereby reducing or preventing exposure of electrical connections at the intermediate connector 214.

[0041] In some embodiments, the first heater wire 206a can comprise two wires 218 and 220, and the second heater wire 206b can comprise two wires 222 and 224. The two wires 218 and 220 of the first section 202a can be electrically coupled to each other via an electrical component 228, the electrical coupling creating an electrical path through the wire 218, at least a portion of the electrical component 228, and the wire 220. Similarly, the two wires 222 and 224 of the second section 202b can be electrically coupled to each other via the electrical component 228 and / or electrically shorted to each other at an end of the section 202b opposite the intermediate connector 202b, e.g., via a patient end connector (not shown) described in more detail herein with reference to Figures 3A, 3B, 8A, 8B, 9, and 13. By joining the wires 222 and 224 of the second section 202b at the intermediate connector 214, 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.

[0042] The intermediate connector 214 can be configured to allow a single controller to control power to the heater wires 206a, 206b, which can be the humidifier controller 122 described herein with reference to FIG. 1. In some embodiments, the humidifier controller 122 controls the heater wires without additional control functionality located in the intermediate connector 214. For example, the intermediate connector 214 can include passive components without logic circuitry, which send power to the heater wires 206a and / or 206b selected by the controller 122. This can allow the intermediate connector 214 to be designed using relatively inexpensive components, reducing design complexity.

[0043] In some embodiments, heating of sections 202a and 202b can be accomplished using up to four wires in each section 202a, 202b. For example, in the first section 202a, the four wires can include a first heater wire 218, a second heater wire 220, a signal sensor wire 228, and a return sensor wire 230. In the second section 202b, the four wires can include a first heater wire 222, a second heater wire 224, a signal sensor wire 232, and a return sensor wire 234. By coupling the second heater wires 222, 224 to the first heater wires 218, 220 at connection points 226, and by coupling the second sensor wires 232, 234 to the first sensor wires 228, 230 at connection points 226, the controller can be configured to provide power to the first heater wires 206a and the second heater wires 206b individually and read sensor data from the sensors 204a and 204b individually, without including more than four wires in the segments 202a or 202b. In some embodiments, control of the heater wires 206a and 206b, and reading of the sensors 204a and 204b can be accomplished using three or fewer wires in each segment (e.g., using three wires, or using two wires), or using five or more wires in each segment (e.g., using five wires, using six wires, using seven wires, using eight wires, or using nine or more wires).

[0044] The intermediate connector 214 may include electrical components 228 configured to allow the controller 122 to selectively control the heater wires 206a, 206b. The controller 122 may be configured to control the heating of the inspiratory limb 202 using two modes, a first control mode including providing power to the heater wires 206a in the first section and a second control mode including providing power to the heater wires 206a and 206b in the first and second sections 202a and 202b. Thus, the controller 122 may be configured to control the heater wire sections individually. This feature allows the controller 122 to control the heating of the inspiratory limb 202 by only controlling the heating of the inspiratory limb according to the first control mode when the second section 202b is not present, thereby allowing the respiratory humidification system 100 to be used in a variety of situations without modifying the controller 122 or the humidification unit 108. In some embodiments, the control mode can include a mode in which power is sent only to the heater wires 206b in the second section 202b. In some embodiments, the controller 122 includes a power source that provides a current. The first and second control modes can be based at least in part on the voltage provided by the power source, where a positive voltage or a positive current can trigger the first control mode and a negative voltage or a negative current can trigger the second control mode. In some embodiments, the power source provides rectified AC or DC power to the heater wires 206a, 206b, and a change in rectification or polarity triggers a change in control mode. By switching between control modes, control of heating in the breathing circuit 200 can be achieved with any power source that can switch the polarity of its output signal. In some embodiments, the amount of power provided 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, 206b, and the duty cycle of the PWM can be adjusted to control the power delivered.In another example, the amount of power provided to the heater wires 206a, 206b can be adjusted by controlling the amplitude of the power signal.

[0045] The intermediate connector 214 can include electrical components 230 configured to allow the controller 122 to selectively read the sensors 204a, 204b. As described herein with reference to Figures 6A, 6B, and 7, selective reading can be accomplished through the use of a current source, where a positive current across wires 228-230 causes the controller 122 to measure a signal from the first sensor 204a, and a negative current across wires 228 and 230 causes the controller 122 to measure a signal from the second sensor 204b, or from both the first and second sensors 204a, 204b. The controller 122 can use the readings from the sensors 204a, 204b to adjust power to the heater wires 206a, 206b, for example, using pulse width modulation. A first sensor 204a may be positioned near the junction or intersection of the first and second sections 202a, 202b and provides the controller 122 with parameters of the gas entering the second section 202b (which may correspond to entering an incubator or other such area having a different ambient temperature). A second sensor 204b may be positioned at the patient end of the second section 202b and provides the controller 122 with parameters of the gas being delivered to the patient or before the final piece upstream of the patient, such as a Y-piece. The controller 122 can use these readings to adjust the power to the heater wires 206a, 206b to maintain the temperature of the gas at the patient end of the inspiratory limb 202 at a target or appropriate temperature. The target or suitable temperature may vary, at least in part, depending on the application and environment in which it is used, and may be about 37° C., about 40° C., at least about 37° C. and / or about 38° C. or less, at least about 36.5° C. and / or about 38.5° C. or less, at least about 36° C. and / or about 39° C. or less, at least about 35° C. and / or about 40° C. or less, at least about 37° C. and / or about 41° C. or less, or at least about 39.5° C. and / or about 40.5° C. 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 section 202b can be calculated by measuring a parameter inside the incubator.

[0046] The controller 122 can independently control the amount of power delivered in the first and second control modes, as described herein. Based at least in part on feedback from the sensors 204a and / or 204b, the controller 122 can independently adjust the power delivered in the first and second control modes, thereby varying the ratio of heater power to the first segment 202a and the second segment 202b.

[0047] In some embodiments, the first sensor 204a is positioned in the gas flow within the inspiratory limb 202. In some embodiments, the intermediate connector 214 or the first section 202a can include mechanical components that reduce turbulence in the gas flow across the first temperature sensor 204a, which can increase the accuracy of the sensor 204a reading. For example, the mechanical connector can have an aerodynamic cross-section, some examples of which are described for the patient end connector with reference to Figures 15B-15E. In some embodiments, the mechanical components that reduce turbulence (e.g., cross-members within the inspiratory line) also secure 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 in the intermediate connector 214, which can be advantageous, for example, when the sensor 204a is a temperature sensor.

[0048] In some embodiments, the intermediate connector 214 includes additional connection points in addition to the connection points 26 shown in Figure 2. The additional connection points can be used to incorporate additional functionality into the breathing circuit, such as a memory device (PROM), a microcontroller, additional circuitry, etc.

[0049] Intermediate Connector Circuit 3A shows a circuit diagram of an exemplary intermediate connector 214, which includes an active rectifying power supply for providing power to heater wires in a segmented inspiratory limb of a breathing circuit, the circuit being configured to power heater wires R1 and R2 in a first segment of the inspiratory limb in a first mode, and heater wires R1, R2, R3, R4 in both segments in a second mode. Alternatively, power can be applied through heater wires R1 and R2 (where resistors are 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.

[0050] The power source is indicated in the figures with the labels VP and VN, which correspond to the terminals of the power source. In one embodiment, the voltage supply is an alternating current (AC) power source. Alternatively, the power source may be a direct current (DC) power source. Although described as diodes in this embodiment, D1 and D2 may include any of a number of different types of flow control devices, such as, for example, but not limited to, rectifiers, transistors, relays, switches, triacs, MOSFETs, thyristors (SCRs), thermostats, etc.

[0051] 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, so that approximately equal currents are drawn from the power supply during each half cycle. Using the circuit shown in FIG. 3A, heaters R1, R2, R3, and R4 can be controlled in two control modes, a first control mode corresponding to providing power only to R1 and R2, and a second control mode corresponding to providing power to R1, R2, R3, and R4. To provide power only to heaters R1 and R2 in the first section 202a (which corresponds to the first control mode), during a positive cycle from the power supply, switch S1 connects to VP and switch S2 connects to VN, and during a negative cycle from the power supply, switch S1 connects to VN and switch S2 connects 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 provide power to the heaters R1, R2, R3, and R4 in the first and second sections 202a, 202b (which corresponds to a second control mode), during a positive cycle from the power source, switch S1 connects to VN and switch S2 connects to VP, and during a negative cycle from the power source, switch S1 connects to VP and switch S2 connects to VN. In the second control mode, current flows through R1, R2, R3, R4, and D2, and D1 prevents current from flowing through the wires and shorting out the heaters R3 and R4. As described herein with reference to FIG. 5, the switching of switches S1 and S2 can be accomplished by hardware or software that adds logic to the system. In some embodiments, the switching of S1 and S2 occurs at the zero crossings 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 not active near the zero crossings. Thus, the switching of switches S1 and S2 can be done with or without zero-crossing switching detection and / or logic.

[0052] Diodes D1 and D2 may dissipate power in the circuit and therefore generate heat. In some embodiments, Schottky diodes may be used when it is desirable to reduce power loss in relatively hot environments. Schottky diodes may 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, heat generated by the diodes may affect the temperature readings of the sensor 204a. To reduce this effect, the diodes may be thermally connected to the airflow path of the circuit. To reduce this effect and to dissipate heat generated by the diodes, the intermediate connector 214 may include a heat sink or pad thermally coupled to the ambient environment. 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 those components and physically located relatively far from the other components, as described with reference to FIGS. 14A-B and 15.

[0053] FIG. 3B shows another circuit diagram of an exemplary intermediate connector 214, which includes an active rectifying power source for providing power to heater wires in a segmented inspiratory limb of a breathing circuit, the circuit being configured to power heater wires R1 and R2 in a first segment of the inspiratory limb in a first mode, and heater wires R1, R2, R3, R4 in both segments in a second mode. As shown in FIG. 3B, only diode D1 can be provided, and the path of power through heater wires R1 and R2 or through heater wires R1-R4 can still be controlled in a manner similar to that described above with respect to FIG. 3A. Diode D2 shown in the circuit of FIG. 3A has been omitted. The circuit shown in FIG. 3B with only one diode D1 can reduce heat generated by the circuit, reduce component costs, and allow for a smaller circuit board. The remainder of the circuit shown in FIG. 3B operates in a manner similar to that described in FIG. 3A. In an embodiment without D2 as shown in Figure 3B, 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 neglected and therefore does not affect the performance of the humidification system.

[0054] In addition to the AC operation described with respect to Figures 3A and 3B, a similar circuit can also be operated with a DC power supply. Switches S1 and S2 can be switched based at least in part on, for example, time, the output current of the power supply, feedback from a sensor, or other control input. Also, in such an embodiment, the circuit shown in Figure 3A or 3B can be used to control heaters R1, R2, R3, and R4 in two control modes, where a first control mode corresponds to providing power only to R1 and R2, and a second control mode corresponds to providing power to R1-R4. To provide power only to heaters R1 and R2 in the first section 202a (which corresponds to the first control mode), switch S1 connects to VP and switch S2 connects 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 3A. However, as shown in Figure 3B, D2 is an optional component. To provide power to the heaters R1, R2, R3, and R4 in the first and second sections 202a, 202b (which corresponds to a second control mode), switch S1 connects to VN and switch S2 connects to VP. In the second control mode, current flows through R1, R2, R3, R4, and D1 prevents current from flowing through the wires and shorting out the heaters R3 and R4. As previously mentioned, switching can be accomplished by hardware or software that adds logic to the system, as described herein with reference to FIG.

[0055] Inspiratory and expiratory limb heater control 1 further illustrates an exemplary respiratory humidification system 100 having an inspiratory limb 202 and an expiratory limb 210, the humidification system 100 configured to control heater wires 206, 212 in both limbs. In some embodiments, the heater wires 212 in the expiratory limb 210 can be electrically coupled to the inspiratory heater wires 206 external to the humidification unit 108 and controller 122, such that control of the expiratory heater wires 212 can be performed without affecting other control modes and without additional switching transistors. Similarly, the expiratory heater wires 212 can also be electrically coupled to the inspiratory heater wires 206 internal to the humidification unit 108. The connection of the expiratory heater wires 212 to the inspiratory heater wires 206 can be made within the humidification system 108, on an intermediate connector 214, within a sensor cartridge in the humidification system 108, or the like. Thus, the controller 122 can control the exhalation heater wires 212 without additional electrical connections at the patient end. The presence of such electrical connections can increase hazards, system complexity, and cost. Examples of electrical couplings between the exhalation heater wires 212 and the inhalation heater wires 206 inside the humidification unit 108 are shown in Figures 4A-4D, 8A, and 8B.

[0056] 4A, the humidification unit 108 may incorporate switches or relays S3 and S4 to select between independent and dependent control of the inspiratory and expiratory heater wires. In some embodiments, the switches or relays are activated when a tube having the appropriate identification (e.g., inspiratory limb or expiratory limb) is connected to the humidification unit 108, for example, by detecting and / or measuring an identification resistor by the humidification unit 108. For example, when the switches are not activated (e.g., both switches S3, S4 are open), the heater wire in the inspiratory limb and / or the heater wire in the expiratory limb may be controlled separately and / or independently.

[0057] When the appropriate tubing is connected or the system determines that the tubing is appropriate, switches S3 and S4 can be closed to simultaneously control the inspiratory and expiratory limbs. The humidification unit 108 can include an inspiratory power supply INSP and an expiratory power supply EXP, where the system can implement switching of each power supply as described herein with reference to FIGS. 3A and 3B. For example, with reference to FIG. 3A, the inspiratory power supply can have switches S1 and S2 configured to selectively send positive and negative cycles to heaters R1-R4. Similarly, with reference to FIG. 4A, the expiratory power supply EXP can include switches configured to selectively send power to the expiratory limb having heaters R5 and R6. In some embodiments, when switches S3 and S4 are closed, both switches in the expiratory power supply EXP can be opened, whereby power is provided to the inspiratory heater wires and the expiratory heater wires by the inspiratory power supply INSP. In some embodiments, the humidification unit 108 does not include an expiratory power supply EXP. In such an embodiment, the inspiratory power supply INSP is used to provide power to the inspiratory heater wires when switches S3 and S4 are open, and to provide power to both the inspiratory and expiratory heater wires when switches S3 and S4 are closed. Thus, the inspiratory limb heater wires 206 can be controlled similarly as described above, but now the system can use switches S3, S4 to simultaneously control power to the expiratory heater wires 212 and the inspiratory heater wires 206 using a unified electrical circuit and / or control system. For example, the humidification unit 108 may operate in two modes for the inspiratory limb 202 (e.g., a first mode in which the humidification unit 108 provides power to heaters R1 and R2 and a second mode in which the humidification unit 108 provides power to heaters R1-R4) while selectively controlling power to heaters R5 and R6 in the expiratory limb, such that the humidification unit 108 may provide power to heaters R5 and R6 or may not provide power to heaters R5 and R6 while operating in the first mode, the second mode, or both modes. As previously discussed, the connection between the inspiratory limb 202 and the expiratory limb 210 may be internal or external to the humidification unit 108.In one embodiment, the connection is made within the sensor cartridge, at the intermediate connector 214, or at another location.

[0058] In some embodiments, an expiratory circuit configured to connect the expiratory heater wires 212 to the controller 122 can be implemented in the intermediate connector 214 shown in FIG. 1. The expiratory circuit can be connected in one or more of several ways. For example, the expiratory circuit can be connected in parallel with the heater wires 206a in the first section 202a or in parallel with the heater wires 206b in the second section 202b. In some embodiments, the intermediate connector 214 can include an internal flying lead that makes the expiratory circuit available at the intermediate connector 214. In some embodiments, the intermediate connector 214 can be connected to an added third channel, thereby eliminating the flying lead between the inspiratory and expiratory circuits. To accommodate such embodiments, a heater wire driver control circuit can be added to the controller 122.

[0059] FIG. 4B illustrates an exemplary embodiment of a humidification system incorporating a power source 405 to provide power to both the inspiratory heater wires R1-R4 and the expiratory heater wires R5 and R6 through a combination of switches or relays S1-S6 and diode D1. In an exemplary embodiment, the humidification system is configured to provide power to the expiratory heater wires when only the inspiratory heater wires R1, R2 in a first section of the inspiratory limb are receiving power (e.g., in a first mode of operation) or when the inspiratory heater wires R1-R4 in both sections are receiving power (e.g., in a second mode of operation). The power source 405 may be any suitable power source, including a power source providing alternating current, for example, in a sine wave, sawtooth wave, square wave, or other form. In some embodiments, the power source 405 may be a transformer providing an alternating current signal at a voltage of at least about 22 VAC, at least about 5 VAC or less than about 30 VAC, at least about 10 VAC or less than about 25 VAC, at least about 12 VAC or less than about 22 VAC.

[0060] With continued reference to FIG. 4B, the humidification system can be configured to provide power to the expiratory heater wires R5, R6 in a first operating mode while the power supply 405 is providing power in the negative cycle. To do so, switches S1, S2, S5, S6 are closed and switches S3, S4 are opened. Current flows from the negative terminal of the power supply 405 through switch S2 and branches to provide power to the heater wires of both the inspiratory and expiratory limbs. In the inspiratory limb, the current flows to the inspiratory heater wire R2, then through D1 to the inspiratory heater wire R1, then through switch S1 back to the positive terminal of the power supply 405. In the expiratory limb, the current flows through switch S6 to the expiratory heater wire R5, then through expiratory heater wire R6, then through switches S5 and S1 back to the positive terminal of the power supply 405.

[0061] Similarly, with continued reference to FIG. 4B, the humidification system can be configured to provide power to the expiratory heater wires R5, R6 in a first operating mode while the power supply 405 is providing power in a positive cycle. To do so, switches S3, S4, S5, S6 are closed and switches S1, S2 are opened. Current flows from the positive terminal of the power supply 405 through switch S3 and branches to provide power to the heater wires of both the inspiratory and expiratory limbs. In the inspiratory limb, current flows through switch S6 to the inspiratory heater wire R2, then through diode D1 to the inspiratory heater wire R1, then through switches S5 and S4 back to the negative terminal of the power supply 405. In the expiratory limb, current flows to the expiratory heater wire R5, then through expiratory heater wire R6, then through switch S4 back to the negative terminal of the power supply 405.

[0062] With continued reference to FIG. 4B, the humidification system can be configured to provide power to the expiratory heater wires R5, R6 in a second operating mode while the power supply 405 is providing power in a positive cycle. To do so, switches S1, S2, S5, S6 are closed and switches S3, S4 are opened. Current flows from the positive terminal of the power supply 405 through switch S1 and branches to provide power to the heater wires of both the inspiratory and expiratory limbs. In the inspiratory limb, the current flows to the inspiratory heater wire R1, then to the inspiratory heater wire R3 without passing through diode D1, then to the inspiratory heater wire R4, then to the inspiratory heater wire R2, then back to the negative terminal of the power supply 405 through switch S2. In the expiratory limb, the current flows through switch S5 to the expiratory heater wire R6, then to the expiratory heater wire R5, then back to the negative terminal of the power supply 405 through switches S6 and S2.

[0063] Similarly, with continued reference to FIG. 4B, the humidification system can be configured to provide power to the expiratory heater wires R5, R6 in a second operating mode while the power supply 405 is providing power in the negative cycle. To do so, switches S3, S4, S5, S6 are closed and switches S1, S2 are opened. Current flows from the negative terminal of the power supply 405 through switch S4 and branches to provide power to the heater wires of both the inspiratory and expiratory limbs. In the inspiratory limb, the current flows through switch S5 to the inspiratory heater wire R1, then to the inspiratory heater wire R3 without passing through diode D1, then to the inspiratory heater wire R4, then to the inspiratory heater wire R2, then back to the positive terminal of the power supply 405 through switches S6 and S3. In the expiratory limb, the current flows to the expiratory heater wire R6, then to the expiratory heater wire R5, then back to the positive terminal of the power supply 405 through switch S3.

[0064] 4C illustrates an exemplary embodiment of a humidification system incorporating a power source 405 to provide power to both the inspiratory heater wires R1-R4 and the expiratory heater wires R5 and R6 through a combination of switches or relays S1-S6 and diodes D1, D2. In an exemplary embodiment, the humidification system is configured to provide power to the expiratory heater wires when only the inspiratory heater wires R1, R2 in a first segment of the inspiratory limb are receiving power (e.g., in a first mode of operation).

[0065] With continued reference to FIG. 4C, the humidification system can be configured to provide power to the expiratory heater wires R5, R6 in a first operating mode while the power supply 405 is providing power in the negative cycle. To do so, switches S1, S2, S5, S6 are closed and switches S3, S4 are opened. Current flows from the negative terminal of the power supply 405 through switch S2 and branches to provide power to the heater wires of both the inspiratory and expiratory limbs. In the inspiratory limb, the current flows to the inspiratory heater wire R2, then through D1 to the inspiratory heater wire R1, then through switch S1 back to the positive terminal of the power supply 405. In the expiratory limb, the current flows through switch S6 and diode D2 to the expiratory heater wire R5, then through expiratory heater wire R6, then through switches S5 and S1 back to the positive terminal of the power supply 405.

[0066] Similarly, with continued reference to FIG. 4C, the humidification system can be configured to provide power to the expiratory heater wires R5, R6 in a first operating mode while the power supply 405 is providing power in a positive cycle. To do so, switches S3, S4, S5, S6 are closed and switches S1, S2 are opened. Current flows from the positive terminal of the power supply 405 through switch S3 and branches to provide power to the heater wires of both the inspiratory and expiratory limbs. In the inspiratory limb, current flows through switch S6 to the inspiratory heater wire R2, then through diode D1 to the inspiratory heater wire R1, then through switches S5 and S4 back to the negative terminal of the power supply 405. In the expiratory limb, current flows through diode D2 to the expiratory heater wire R5, then through expiratory heater wire R6, then through switch S4 back to the negative terminal of the power supply 405.

[0067] With continued reference to FIG. 4C, the humidification system can be configured to provide power only to the inhalation heater wires R1-R4 (and not to the exhalation heater wires R5, R6) in a second mode of operation while the power supply 405 is providing power in the positive cycle. To do so, switches S1, S2, S5, S6 are closed and switches S3, S4 are opened. Current flows from the positive terminal of the power supply 405 through switch S1 to the inhalation heater wire R1, then to the inhalation heater wire R3, inhalation heater wire R4, inhalation heater wire R2 without passing through diode D1, and back to the negative terminal of the power supply 405 through switch S2. Current does not flow through the exhalation heater wires due to diode D2. Diode D2, in conjunction with a switch configured as described above, blocks current flow through the circuit in the positive cycle.

[0068] With continued reference to FIG. 4C, the humidification system can be configured to provide power only to the inhalation heater wires R1-R4 (and not to the exhalation heater wires R5, R6) in a second mode of operation while the power supply 405 is providing power on the negative cycle. To do so, switches S3, S4, S5, S6 are closed and switches S1, S2 are opened. Current flows from the positive terminal of the power supply 405 through switches S4 and S5 to the inhalation heater wire R1, then to the inhalation heater wire R3, the inhalation heater wire R4, the inhalation heater wire R2 without passing through diode D1, and back to the negative terminal of the power supply 405 through switches S6 and S3. Current does not flow through the exhalation heater wires due to diode D2. Diode D2, together with a switch configured as described above, blocks current flow through the circuit on the negative cycle.

[0069] FIG. 4D illustrates an exemplary embodiment of a humidification system incorporating a power source 405 that provides power to both the inspiratory heater wires R1-R4 and the expiratory heater wires R5 and R6 through a combination of switches or relays S1-S6 and diode D1, with the expiratory heater wires R5, R6 electrically coupled to the inspiratory heater wires R1-R4 at the patient ends of the heater wires in the first section of the inspiratory limb, which may result in an intermediate connector, such as any of the intermediate connectors described herein. As described with reference to FIG. 4D, the expiratory heater wires R5, R6 are coupled to the inspiratory heater wires R1-R4 at an intermediate connector, although any suitable location after the inspiratory heater wires in the first section may be used to couple the heater wires of the inspiratory and expiratory limbs. In an exemplary embodiment, the humidification system is configured to provide power to the expiratory heater wires only when the inspiratory heater wires R1-R4 in both sections of the inspiratory limb are receiving power (e.g., only in the second mode of operation).

[0070] With continued reference to FIG. 4D, the humidification system can be configured to provide power to the inspiratory heater wires R1-R4 and the expiratory heater wires R5, R6 in a second mode of operation while the power supply 405 is providing power in a positive cycle. To do so, switches S1, S2, S5, S6 are closed and switches S3, S4 are opened. Current flows from the positive terminal of the power supply 405 through switch S1 to the inspiratory heater wire R1 and then branches to provide power to the heater wires of both the second section of the inspiratory limb and the expiratory limb without passing through diode D1. In the second section of the inspiratory limb, the current flows to the inspiratory heater wire R3 and then to the inspiratory heater wire R4 and back to the intermediate connector. In the expiratory limb, the current flows to R5 and then to R6 and back to the intermediate connector. The current then flows through the inspiratory heater wire R2 and then back through switch S2 to the negative terminal of the power supply 405.

[0071] Similarly, with continued reference to FIG. 4D, the humidification system can be configured to provide power to the expiratory heater wires R5, R6 in a second operating mode while the power supply 405 is providing power in the negative cycle. To do so, switches S3, S4, S5, S6 are closed and switches S1, S2 are opened. Current flows from the negative terminal of the power supply 405 through switches S4 and S5 to the inspiratory heater wire R1, and then branches to provide power to the heater wires of both the second section of the inspiratory limb and the expiratory limb without passing through diode D1. In the second section of the inspiratory limb, the current flows to the inspiratory heater wire R3, then to the inspiratory heater wire R4, and back to the intermediate connector. In the expiratory limb, the current flows to R5, then to R6, and back to the intermediate connector. The current then flows through the inspiratory heater wire R2, and then through switches S6 and S3 to return to the positive terminal of the power supply 405.

[0072] 4D, the humidification system can be configured to provide power only to the inspiratory heater wires R1 and R2 in the first section of the inspiratory limb (and not to the expiratory heater wires R5, R6) in a first mode of operation while the power supply 405 is providing power on the negative cycle. To do so, switches S1, S2, S5, S6 are closed and switches S3, S4 are opened. Current flows from the negative terminal of the power supply 405 through switch S2 to the inspiratory heater wire R2, then through diode D1 to the inspiratory heater wire R1, and then back through switch S1 to the positive terminal of the power supply 405.

[0073] Similarly, with continued reference to FIG. 4D, the humidification system can be configured to provide power only to the inspiratory heater wires R1 and R2 in the first section of the inspiratory limb (and not to the expiratory heater wires R5, R6) in a first mode of operation while the power supply 405 is providing power in a positive cycle. To do so, switches S3, S4, S5, S6 are closed and switches S1, S2 are opened. Current flows from the positive terminal of the power supply 405 through switches S3 and S6 to the inspiratory heater wire R2, then through diode D1 to the inspiratory heater wire R1, and back to the negative terminal of the power supply 405 through switches S5 and S4.

[0074] Detection of the articulated extension of the inspiratory limb FIG. 5 illustrates a block diagram of an exemplary system 500 configured to detect the presence of an inspiratory limb extension using an extension detection module 502 and provide power to a heater wire in the inspiratory limb (e.g., a first section of the inspiratory limb), an inspiratory limb extension (e.g., a second section of the inspiratory limb), and / or an expiratory limb. As described with reference to FIGS. 3A, 3B, 4, 8A, and 8B, for example, a logic module 504 (which may comprise hardware, software, or some combination of both) may be configured to provide logic to enable the switching described with respect to the various control modes. The logic module 504 may receive signals from an integrated circuit 506 that is part of the respiratory humidification system 100. In some embodiments, the logic module 504 is software embedded in whole or in part in the integrated circuit 506 and converts signals from the integrated circuit 506. The combination of the logic module 504 and the integrated circuit 506 may be configured to detect zero level crossings, i.e., points at which a voltage or current transitions from positive to negative or vice versa, and change the state of a switch according to the control module. The logic module 504 can output PWM signals 508a, 508b according to a desired, selected, or predetermined power output, where the PWM signals are delivered to the inhalation heater wires (INSP HW), the exhalation heater wires (EXP HW), or both.

[0075] In some embodiments, the system 500 can include an extension detection module 502 configured to detect whether the second section 202b is connected to the breathing circuit 200. The extension detection module 502 can generate an "enable signal" if the second section 202b is connected. The logic module 504 can receive the "enable signal" and adjust the switching accordingly. In some embodiments, the "enable signal" indicates to the logic module 504 that the system 500 does not control the inspiratory and expiratory circuits independently and simultaneously.

[0076] In some embodiments, the extension detection module 502 can be configured to detect the presence of the second section 202b by switching on both the inhalation and exhalation circuits and detecting whether a hardware overcurrent event is detected. When no overcurrent event is detected when each is switched on individually, but an overcurrent event is detected when both are switched on simultaneously, the extension detection module 502 can generate an "enable signal" indicating that the second section 202b is connected. In some embodiments, the extension detection module 502 can detect the presence of the second section 202b by detecting the resistance of an identification resistor or heater wire in each section using current measurements. Based at least in part on the current measurements of the various sections, the extension detection module 502 can generate an "enable signal" when the current measurements for the various cycles in which the various control modes are implemented are different as described above with reference to Figures 3A, 3B, 4, 8A, and 8B.

[0077] Sensor Circuit 6A and 6B show an exemplary circuit diagram in the respiratory humidification system 100, where a circuit 600 is configured to read data from two sensors R1 and R2. With reference to FIGS. 6A and 6B, the sensors R1 and R2 are represented using resistors, but any suitable type of sensor can be used, such as, for example, but not limited to, a temperature sensor, a humidity sensor, a flow sensor, an oxygen sensor, etc. In some embodiments, the sensor can be a temperature sensor, such as a thermistor. In such an embodiment, the sensors R1 and R2 respectively represent a first thermistor at the intermediate connector 214 and a second thermistor at the patient end (e.g., the patient end connector) of the breathing circuit 200. The two thermistors R1 and R2 can be measured using two wires in the breathing circuit 200 using the circuit 600 with a current or voltage source and a switch in the humidifier controller 122. Although this description with reference to Figures 6A and 6B is in terms of a thermistor, other suitable sensors that affect the voltage and / or current provided to an associated circuit are also applicable.

[0078] To selectively read sensors R1 and R2, current is provided in either polarity via lines 602 and 604. To measure patient-end sensor R2, the humidifier controller 122 sets a switch to ground the top current source. Current then flows from the bottom current source through R2, through the switch to ground. Diode D1 prevents current from passing through R1. The humidifier controller 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 current provided and the measured voltage. To measure sensor R1 positioned at the middle connector 214, the humidifier controller 122 can read the patient-end sensor R2 and record the results. The humidifier controller 122 can then set a switch to ground the bottom current source. Current then flows from the top current source through R1 and R2, through the switch to ground. The humidifier controller 122 can be configured to measure the voltage drop from the upper current supply to ground and derive the resistance of the sensor R1 based at least in part on the current supplied, the measured voltage, and the recorded results from measuring 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 FIG. 6A, by placing D1 close to R1, the temperature of the diode D1 can be calculated, and this temperature can be used to calculate the voltage drop across D1. One possible advantage of the configuration shown in FIG. 6A is that the measurement of the sensor R2 at the patient end can be more accurate because the measurement is made without passing through a diode as illustrated in the embodiment of FIG. 6B. Passing through a diode can introduce uncertainty or error.

[0079] In some embodiments, an additional diode D2 can be added to the intermediate connector 214, as shown in FIG. 6B. In such an embodiment, the humidifier controller 122 can be configured to measure sensors R1 and R2 similar to the embodiment shown in FIG. 6A and described above. The difference is that when measuring sensor R1, current flows through R1 and D1, but not through R2, as diode D2 prevents current flow 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 close to R1, the temperature of the diodes can be calculated, which can be used when calculating the voltage drop across D1 and D2, respectively.

[0080] In a particular embodiment, the measurement of the sensors R1, R2 is performed by software running on a controller connected to the circuit of FIG. 6A or FIG. 6B. The direction and amount of current supplied to the circuit can be controlled by such software. An accurate measurement of the resistance of the sensors R1, R2 can be obtained by measuring the voltage, for example, using an analog-to-digital converter. To minimize or prevent the effect of the changes caused by the diodes D1 and / or D2, the software can supply two different currents (I1 and I2) in the same direction. This results in 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 of the diodes D1, D2 and the resistance for the sensors R1, R2. For the sensor R1, for example, the voltage drop can be determined 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 in software. In one embodiment, Vdrop is increased by about 15% as error compensation.

[0081] FIG. 7 shows an exemplary circuit diagram in the respiratory humidification system 100, where the circuit 700 is configured to read temperature data using two transistors Q1 and Q2 acting as temperature sensors. The temperature measurement may be based at least in part on the temperature effect of the pn junction of the base and emitter terminals of the transistors. The switching of the current in the humidifier controller 122 may be the same as for the circuit described with reference to FIGS. 6A and 6B, or may be an alternating configuration as shown. For example, the switching configuration shown uses two switches with two power sources and two grounds to selectively provide power to the wires. In a first configuration, the top switch electrically connects the top power source to the wire 702, and the bottom switch electrically connects the ground to the wire 704. In a second configuration, the top switch electrically connects the ground to the wire 702, and the bottom switch electrically connects the bottom power source to the wire 704. By using transistors Q1 and Q2 as temperature sensors, the diodes can be omitted since the transistors provide the function of the temperature sensor and the diode.

[0082] Breathing circuit hardware configuration FIG. 8A shows an example diagram of a hardware configuration 800 for a breathing circuit 200 having a first section 202a of the inspiratory limb, a second section 202b of the inspiratory limb, and an expiratory limb 210. The hardware configuration 800 can include a humidifier 108 configured to couple the wiring of heater wires HW1 and HW2 via switches or relays S3 and S4, and to couple wiring for sensors 204a, 204. In some embodiments, a sensor cartridge 802 can be configured to couple the wiring of heater wires HW1, HW2 and wiring for sensors 204a, 204. Switches S3, S4 can be used to selectively control power to the heater wire HW2 of the expiratory limb 210, as described with reference to FIG. 4A, with similar functionality as described with reference to FIGS. 4B-4D. In some embodiments, both switches S3 and S4 are in an open position by default and are closed when the appropriate tube (e.g., inspiratory limb or expiratory limb with the appropriate discrimination resistor) is connected to the humidifier 108. In this manner, the hardware configuration 800 can be used to provide power to the heater wire HW1 and / or heater wire HW2. Regardless of whether the heater wire HW2 is receiving power, the heater wire HW1 can be controlled in two modes. In the first mode, the first heater wire 206a receives power and the second heater wire 206b does not. In the second mode, the first and second heater wires 206a, 206b receive power. In the illustrated embodiment, the heater wire HW2 can be powered when the heater wire HW1 is controlled in either the first or second mode. It should be understood that the heater wire HW2 of the expiratory limb can be selectively controlled and the heater wire HW1 of the inspiratory limb is single mode. For example, when the inspiratory limb heater wire HW1 is controlled in a first mode (or a second mode), the expiratory limb heater wire HW2 can alternate between receiving and not receiving power based at least in part on the operation of switches S3 and S4 without changing the control mode of the heater wire HW1.Similarly, the heater wire HW2 in the expiratory limb may remain receiving power while the heater wire HW1 in the inspiratory limb is changed between the first and second modes.

[0083] The hardware configuration 800 may include an intermediate printed circuit board (PCB) 214 that includes two diodes, one of which is a power diode D1 and the other is a signal diode D3. The intermediate PCB 214 may include a heat pad to dissipate heat generated by the diodes D1, D3 and reduce the effect on the sensor 204a. The hardware configuration 800 may include a patient-end PCB 804 with two heater wires and one sensor 204b, with the heater wire 206b electrically directly coupled. In a first mode of operation, power may be provided to HW1 such that current flows through the heater wire 206a and the diode D1, while substantially no current flows through the heater wire 206b (e.g., less than 1% of the current through the heater wire 206a flows through the heater wire 206b). In a second mode of operation, power may be provided to HW1 such that current flows through the heater wires 206a and 206b. The first and second modes of operation can be controlled at least in part by the direction of current through the heater wire HW1.

[0084] In certain embodiments, diodes D2 and D4 can be added to the hardware configuration 800 as shown in FIG. 8B. In such embodiments, the software for the sensing circuit can be modified to take into account the increase in heat. In some embodiments, the signal diodes D3, D4 are positioned close to each other so that they experience the same or similar ambient conditions, reducing differences in effects caused by different ambient temperatures. Otherwise, the circuit 200 operates similarly to the circuit shown in FIG. 8A.

[0085] In some embodiments, comparing Figures 8A and 8B, omitting diode D4 improves sensing reliability at the patient end. For example, the diode may fail in an open position. If diode D4 fails open, a patient end temperature reading may not be possible. In the circuit shown in Figure 8A, if diode D3 fails, the patient end sensor 204b can still be read. Omitting diode D2 may have similar advantages.

[0086] In some embodiments, the sensor cartridge 802 can be located internal to the humidification system 100 or external to the system.

[0087] Exemplary Segmented Inspiratory Limb with Connector Having a Microcontroller FIG. 9 shows an exemplary embodiment of a respiratory humidification system 100 that utilizes a microcontroller at the intermediate connector 214 to measure data for controlling heating and reading sensor values ​​at the inspiratory limb 202. In some embodiments, one or more microcontrollers can be incorporated into the sensor cartridge, the humidifier, the intermediate connector 214, or any combination thereof. When incorporated into the sensor cartridge, for example, the microcontroller provides similar functionality as described herein. The exemplary embodiment shown uses one heater wire connected to VN as a common reference and connects the two heater wires HW1, HW2 and the sensor wires to the common reference. The exemplary embodiment also converts the readings of both sensors 204a, 204b to digital signals at the signal intermediate connector 214 and sends them to the humidifier controller 122. This can reduce or prevent isolation issues by providing a common reference point for the sensors 204a, 204 and sending digital parameter readings. The readings can be passed through an optocoupler in the controller 122, which isolates the signals as described herein with reference to Figure 12. Use of this exemplary embodiment allows two independent control channels to heat only the first section 202a or the first and second sections 202a, 202b of the inspiratory limb to provide desired, selected, or predetermined heating control.

[0088] FIG. 10 shows a block diagram of the intermediate connector 214 for the inspiratory limb 202, where the intermediate connector 214 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 signal can be sent to the humidifier controller 122 on a single data line. The data line can be used to enable communication between the microcontroller and the humidifier controller 122 to provide temperature data. The data line can be used to provide power to the microcontroller by pulling the data line high at the humidifier controller 122 when no data is being transmitted. The power module and data line converter can include a capacitor and a diode, so that the capacitor is charged when the data line is high. The charged capacitor can be used to power the microcontroller when the data line is being used for communication. A circuit diagram for an exemplary power module and data line converter is shown in FIG. 11.

[0089] Temperature sensing using this configuration can be accomplished using a current or voltage source at the intermediate connector 214 to drive a thermistor, which can then be read by the microcontroller. This can be done using transistors or op-amps, for example. Data line communication can be accomplished using a time slot based approach, where each logic level can be sent and read within a given time slot. In this way, a single wire can be used to enable bidirectional communication between the humidifier controller 122 and the microcontroller.

[0090] The humidifier controller 122 may include a DC power supply referenced to VN. A capacitor may be included that may charge when the heater wires are on and provide power to the microcontroller while the heater wires are switched off. The humidifier controller 122 may include a dual optocoupler circuit 1200 as shown in FIG. 12. The dual optocoupler circuit may be used to isolate signals and provide bidirectional data communication between the controller 122 and the power supply.

[0091] In some embodiments, calibration data can be stored in the microcontroller, which can be read out when a breathing circuit is connected. In some embodiments, a part identification number or serial number can be stored to identify the manufacturer of the connected circuit.

[0092] Segmented Inspiratory Limb with Digital Temperature Sensor 13 shows a circuit diagram of an exemplary respiratory humidification system 100 incorporating digital temperature sensors 204a, 204b for use with a breathing circuit 200 having a first section 202a and an intermediate connector 214 joining a second section 202b to form an inspiratory limb 202. As with the design described with reference to FIG. 9, the digital temperature sensors 204a, 204b can utilize a single line for communication and power supply, simplifying the circuit design and reducing the amount of wires used in the system 100. The design shown in FIG. 13 allows the temperature sensor and data communication to be implemented as a single chip rather than a combination of circuit elements, which may be desirable.

[0093] Intermediate Connector Board 14A and 14B show an example intermediate PCB 250 of the intermediate connector 214, with each view showing one of two sides of the intermediate PCB 250. The intermediate PCB 250 includes connection pads 252, 254 for the heater wires and the sensor connection lines. The connection pads 252, 254 are configured on both sides of the intermediate PCB 250 to facilitate connection with the heater wires spirally wrapped around the inspiratory limb.

[0094] The intermediate PCB 250 includes a sensor connection pad 256 for a sensor, such as a thermistor or other temperature measuring component, or a humidity sensor, or a flow sensor. The sensor can be coupled to a diode (e.g., diode D3 described with reference to FIG. 8B) via a signal connection pad 258 on the intermediate PCB 250. As shown, the intermediate PCB 250 includes a gap 262 configured to insulate the sensor from other electrical components and tracks. In some embodiments, the gap 262 can be filled with an insulating material to further insulate the sensor connected to the sensor connection pad 256. Additionally, the intermediate PCB 250 can be configured to position the sensor away from other active and / or passive electrical components, such as by a protrusion 257.

[0095] The intermediate PCB 250 includes a power connection pad 260 for a diode that is electrically coupled to the heater wires via electrical tracks on the intermediate PCB 250. The diode may be diode D1 as described with reference to Figures 3B, 6B, or 8B. The power connection pad 260 may be electrically and thermally coupled to a heat sink 264 to help dissipate heat and reduce or minimize the effect on the accuracy of parameter readings of the sensor coupled to the sensor connection pad 256.

[0096] 14C and 14D show an exemplary embodiment of an intermediate connector 214 comprising an intermediate PCB 250 and an intermediate connection element 263. The intermediate connection element 263 can be configured to route a portion of the humidified gas flowing through the inspiratory limb through a conduit formed by the intermediate connection element 263. A sensor on the intermediate PCB 250 can then provide a signal corresponding to a parameter of the gas flowing through the intermediate connection element 263, the parameter representing at least one characteristic (e.g., temperature, humidity, flow rate, oxygen content, etc.) of the humidified gas in the inspiratory limb at that time. In some embodiments, the intermediate connection element 263 is configured to provide mechanical support for the intermediate PCB 250 to position the intermediate PCB 250 within the inspiratory limb. In some embodiments, the intermediate connection element 263 is configured to provide mechanical support for joining two sections of the inspiratory limb at or near the intermediate connector 214.

[0097] The intermediate connector 214 includes a first connection pad 252 on a first side of the intermediate PCB 250 and a second connection pad 254 on a second side of the intermediate PCB 250 (the opposite side of the intermediate PCB 250). As described herein, the first and second connection pads 252, 254 can be configured to provide electrical contacts for heater wires in first and second sections of the segmented inspiratory limb, respectively. In some embodiments, the heater wires in the sections of the inspiratory limb are spirally wound. The intermediate PCB 250 is configured to electrically couple the spirally wound heater wires and / or signal wires (e.g., temperature sensor wires) in the first section to the spirally wound heater wires and / or signal wires in the second section.

[0098] In some embodiments, the intermediate PCB 250 includes a first portion that extends across the lumen formed by the intermediate connection element 263 along a diameter or chord line, such that a portion of the intermediate PCB 250 generally crosses at least a portion of the flow path of the gas. The first portion of the intermediate PCB 250 can be overmolded with an overmolding composition. The intermediate PCB 250 can include a second portion 251 adjacent to the first portion, the second portion 251 projecting outwardly from the outside of the intermediate connection element 263 in a direction away from the lumen. The second portion 251 of the intermediate PCB 250 includes one or more connection pads 252 configured to receive one or more wires from the first segment of the inspiratory limb. The intermediate PCB 250 can include a third portion 253 adjacent to the first portion, the third portion 253 projecting outwardly from the outside of the intermediate connection element 263 in a direction away from the lumen and opposite the second portion 251. The third portion 253 may include one or more connection pads 254 on the intermediate PCB 250 configured to receive one or more wires from the second segment of the inspiratory limb. The intermediate PCB 250 includes one or more conductive tracks configured to electrically couple the one or more connection pads 252 of the second portion 251 to the one or more connection pads 254 of the third portion 253 and to provide an electrical connection between the wires in the first and second segments of the inspiratory limb.

[0099] Patient End Connector Board FIG. 15A illustrates an exemplary patient-end PCB 270 of the patient-end connector 804. The patient-end PCB 270 includes connection pads 272 for the heater wires and the sensor connection wires. The connection pads 272 are configured to be on only one side of the patient-end PCB 270 to connect to the spirally wound heater wires and the signal wires from the inspiratory limb. Two of the connection pads 272 can be electrically directly coupled to each other as an electrical pathway. The heater wires can be coupled to the electrically directly coupled connection pads 272. The remaining two connection pads 272 can be electrically coupled to a sensor connection pad 274. The electrical tracks 278 to and from the sensor connection pads 274 can be configured to reduce or minimize the trace width and increase or maximize the track length to insulate the sensors connected to the sensor connection pads 274. The patient-end PCB 270 can include a protrusion 276 similar to that described with reference to the PCB 250 illustrated in FIGS. 14A and 14B. The protrusion 276 can be configured to further insulate the sensor from the effects of currents and components on the patient-end PCB 270.

[0100] Figures 15B-15E show an exemplary embodiment of the patient-end connector 804. Figures 15B and 15D show an exemplary embodiment of a patient-end PCB 270 that is overmolded as part of the inspiratory limb 202. The cross-sections of the patient-end PCB 270 shown in Figures 15C and 15E, respectively, can be aerodynamically configured to reduce or minimize turbulence in the gas delivered to the patient.

[0101] Segmented Inspiratory Limb Placement Limiter 16A-16E illustrate an exemplary embodiment of a placement limiter 280 for a segmented inspiratory limb 202. FIG. 16A illustrates an exemplary placement limiter 280 configured to have a larger chamber end 282 (e.g., the end closer to the gas source), a smaller patient end 284, and a sharp corner 286 with a groove 288 into which a grommet 294 can be placed. The placement limiter 280 can be configured to prevent or reduce the possibility of an intermediate connector or segment connection point of the inspiratory limb 202 (e.g., where the intermediate PCB 250 is located) from entering the incubator 290 through an opening 292. The smaller end 284 can be configured to enter the incubator 290, while the larger end 282 can be configured to prevent or block entry through the incubator opening 292 by contacting the grommet 294. In some embodiments, the position limiter 280 is configured to substantially fix the position of the intermediate PCB 250 within a target or desired distance from the incubator, or other such point that defines a different temperature environment. The target or desired distance may be about 20 cm or less, about 10 cm or less, about 5 cm or less, or about 0 cm. FIG. 16B illustrates an exemplary position limiter 280 for use with a bubble tube 202, where the position limiter is located a distance d1 from an entrance 292 to an incubator 290.

[0102] FIG. 16C illustrates an exemplary embodiment of a position limiter 280 configured to be clipped or secured to an object such as clothing, a blanket, or other object separate from the patient. The position limiter 280 is configured to be secured to the inspiratory limb 202 and capable of moving along the inspiratory limb 202 to adjust the position of the inspiratory limb 202. FIG. 16D illustrates the inspiratory limb 202 with the position limiter 280 in use with an incubator 290 to block or prevent entry of the intermediate PCB connector 250 into the incubator 290. FIG. 16E illustrates the inspiratory limb 202 with the position limiter 280 in use with a patient, where the position limiter 280 is secured to the patient's blanket to block or prevent movement of the inspiratory limb 202 relative to the patient and / or blanket. The position limiter 280 may also be used with an expiratory limb or other medical tubing used in connection with a gas delivery system.

[0103] Sectionalized medical tubing for use with respiratory humidification systems FIG. 17A 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 FIG. 1. The composite tube 1201 can be used as the inspiratory limb 202 and can be configured to provide thermally beneficial properties that help prevent condensation of gas along the tube as described herein. The composite tube 1201 includes multiple elongated members wrapped and joined to form a pathway, where the multiple elongated members can 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 the inspiratory limb 202 can reduce condensation and rainout and maintain a more desirable or targeted temperature profile along the length of the inspiratory limb 202. The walls of the composite tube can provide a greater thermal mass, which is more resistant to temperature changes and increases 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 more precisely controlled, and less power or energy can be lost in controlling the temperature of the gas delivered to the patient. In some embodiments, a composite tube 1201 can also be used as the expiratory limb 210.

[0104] In general, the composite tube 1201 comprises a first elongated member 1203 and a second elongated member 1205. Member is a broad term and should be interpreted in its ordinary and customary sense to one of ordinary skill in the art (i.e., not limited to a special or specialized sense), including, but not limited to, an integral portion, an integral component, and a distinct component. Thus, while FIG. 17A illustrates an embodiment formed from two distinct components, it should be understood that in other embodiments, the first elongated member 1203 and the second elongated member 1205 can represent regions within a tube formed from a single material. Thus, the first elongated member 1203 can be a hollow portion of the tube, and the second elongated member 1205 is 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 can have a helical configuration. Composite tube 1201 may be used to form the inspiratory limb 202 and / or expiratory limb 210 described herein, the coaxial tubes described below, or any other tubes described elsewhere in this disclosure.

[0105] In this example, the first elongated member 1203 comprises a helically wound hollow body at least partially forming an elongated tube having a longitudinal axis LA-LA and 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. Additionally, the first elongated member 1203 is preferably transparent, or at least translucent or semi-opaque. A degree of translucency allows a caregiver or user to inspect the lumen 1207 for blockages or contaminants, or to identify 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 blends, and thermoplastic polyurethanes.

[0106] The hollow body structure of the first elongated member 1203 contributes insulating properties to the composite tube 1201. An 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 gas in a conditioned state with less or minimal energy loss.

[0107] In at least one embodiment, the hollow portion of the first elongated member 1203 is filled with a gas. The gas can be air, which has a low thermal conductivity (2.62×10 at 300 K). -2 W / m K) and very low cost. Also, advantageously, gases more viscous than air can be used, since higher viscosity reduces convective heat transfer. Thus, argon (17.72×10 at 300 K) -3 W / m K), krypton (9.43 × 10 at 300 K) -3 W / m K), and xenon (5.65 × 10 at 300 K). -3 Gases such as 1200 W / m·K can enhance the thermal insulation. Each of these gases is non-toxic, chemically inert, flame-resistant, and commercially available. The hollow portion of the first elongated member 1203 can be sealed at both ends of the tube, substantially stagnating the gas therein. Alternatively, the hollow portion can 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 controller. The first elongated member 1203 can be optionally perforated. For example, a surface of the first elongated member 1203 can be perforated on the outward facing surface opposite the lumen 1207. In another embodiment, the hollow portion of the first elongated member 1203 is filled with a liquid. An example of the liquid can be water or other biocompatible liquid with a high heat capacity. For example, a nanofluid can be used. An exemplary nanofluid with suitable heat capacity includes water and nanoparticles of a material such as aluminum.

[0108] The second elongated member 1205 is also helically wound 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 serves as structural support for the first elongated member 1203.

[0109] In at least one embodiment, the second elongate member 1205 is wider at the base (proximal to the lumen 1207) and narrower at the top. For example, the second elongate member may be generally triangular, generally T-shaped, or generally Y-shaped. However, any shape that matches the contour of the corresponding first elongate member 1203 is suitable.

[0110] Preferably, the second elongated member 1205 is flexible to facilitate bending of the tube. Desirably, the second elongated member 1205 is 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 elastic modulus of the second elongated member 1205 is preferably 30-50 MPa (or about 30-50 MPa). The elastic modulus of the first elongated member 1203 is less than the elastic modulus of the second elongated member 1205. The second elongated member 1205 may be solid or nearly solid. Additionally, the second elongated member 1205 may encapsulate or house a conductive material, such as a filament, particularly a heating filament, or a sensor (not shown). The heating filament may minimize cold surfaces on which condensation from moist air may occur. A heating filament may also be used to change the temperature profile of the gas within the lumen 1207 of the composite tube 1201. A variety of 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 blends, 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 than 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.

[0111] This spirally wound structure with a flexible hollow body and integral supports can provide compression resistance while allowing the tube walls to be flexible enough to allow short radius bending without buckling, plugging, or collapsing. Preferably, the tube can be bent around a 25 mm diameter metal cylinder without buckling, plugging, or collapsing as defined in the test for increase in flow resistance with bending according to ISO 5367:2000(E). This structure can also provide a smooth lumen 1207 surface (tube bore), which helps keep the tube free of deposits and improves gas flow. The hollow body has been found to improve the insulating properties of the tube while keeping it lightweight.

[0112] As explained above, the composite tube 1201 can be used as an expiratory and / or inspiratory tube in a breathing circuit, or as part of a breathing circuit. Preferably, the composite tube 1201 is used at least as an inspiratory tube.

[0113] FIG. 17B shows a longitudinal cross-section of the top of the exemplary composite tube 1201 of FIG. 17A. FIG. 17B has the same orientation as FIG. 17A. This example further illustrates the hollow body shape of the first elongated member 1203. As can be seen in this example, the first elongated member 1203 forms a plurality of hollow air bubbles in the longitudinal cross-section. A portion 1209 of the first elongated member 1203 overlaps an adjacent turn of the second elongated member 1205. A portion 1211 of the first elongated member 1203 forms the wall of the lumen (lumen).

[0114] It has been surprisingly discovered that having gaps 1213 between adjacent turns of the first elongated member 1203, i.e., between adjacent bubbles, improves the overall thermal insulation properties of the composite tube 1201. Thus, in certain embodiments, adjacent bubbles are separated by gaps 1213. Additionally, certain embodiments include the realization that providing gaps 1213 between adjacent bubbles increases the heat transfer resistance (R-value) and therefore decreases the thermal conductivity of the composite tube 1201. This gap configuration has also been found to improve the flexibility of the composite tube 1201 by allowing for shorter radius bends. As shown in FIG. 17B, the T-shaped second elongated member 1205 can help maintain the gaps 1213 between adjacent bubbles. Nevertheless, in certain embodiments, adjacent bubbles are in contact. For example, adjacent bubbles can be bonded together.

[0115] One or more conductive materials may be disposed 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, one on each side of the vertical portion of the "T". The heating filaments 1215 include conductive materials such as alloys of aluminum (Al) and / or copper (Cu) and conductive polymers. Preferably, the material forming the second elongated member 1205 is selected so that it does not react with the metals 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 that they are not exposed to the lumen 1207. At one end of the compound tube, several pairs of filaments may be formed as connected loops.

[0116] In at least one embodiment, multiple filaments are disposed within the second elongated member 1205. The filaments can be electrically connected to each other and share a common rail. For example, a first filament, such as a heating filament, can be disposed on a first side of the second elongated member 1205. A second filament, such as a sensing filament, can be disposed on a second side of the second elongated member 1205. A third filament, such as a ground filament, can be disposed between the first and second filaments. The first, second, and / or third filaments can be connected to each other at one end of the second elongated member 1205.

[0117] FIG. 17C shows a longitudinal cross section of the foam in FIG. 17B. As shown, the portion 1209 of the first elongate member 1203 that overlaps the adjacent turn of the second elongate member 1205 is characterized by some bond area 1217. The larger bond area improves the resistance of the tube to delamination at the interface of the first and second elongate members. Additionally or alternatively, the shape of the bead and / or foam can be adapted to increase the bond area 1217. For example, FIG. 17D shows a relatively small bond area on the left side. Also, FIG. 19B shows a smaller bond area. In contrast, FIG. 17E has a much larger bond area than that shown in FIG. 17D due to the size and shape of the bead. FIGS. 19A and 19C also show larger bond areas. Each of these figures is discussed in more detail below. It should be understood that while the configurations in Figures 17E, 19A, and 19C may be preferred in certain embodiments, other configurations, including the configuration in Figure 17D, the configuration in Figure 19B, and other variations, may be utilized in other embodiments, if desired.

[0118] Figure 17D shows a longitudinal cross section of the top of another composite tube. Figure 17D has the same orientation as Figure 17B. This example further illustrates the hollow body shape of the first elongated member 1203 and how the first elongated member 1203 forms multiple hollow air bubbles in the longitudinal cross section. In this example, the bubbles are completely separated from each other by gaps 1213. A generally triangular second elongated member 1205 supports the first elongated member 1203.

[0119] FIG. 17E shows a longitudinal cross section of the top of another composite tube. FIG. 17E has the same orientation as FIG. 17B. In the example of FIG. 17E, the heating filaments 1215 are spaced farther apart from each other than the filaments 1215 in FIG. 17B. It has been discovered that increasing the space between the heating filaments can improve the heating efficiency. Certain embodiments include this realization. Heating efficiency represents the ratio of the amount of heat entering the tube to the amount of energy exiting or recoverable from the tube. In general, the more energy (or heat) dissipated from the tube, the lower the heating efficiency. For improved heating performance, the heating filaments 1215 can be evenly (or nearly evenly) positioned along the bore of the tube. Alternatively, the filaments 1215 can be positioned at the end of the second elongated member 1205, which may allow for simpler manufacturing.

[0120] Reference is now made to Figures 18A-18G, which illustrate exemplary configurations for the second elongated member 1205. Figure 18A illustrates a cross-section of a second elongated member 1205 having a shape similar to the T-shape shown in Figure 17B. In this exemplary embodiment, the second elongated member 1205 does not have a heating filament. Other shapes for the second elongated member 1205 may also be utilized, including variations of the T-shape as described below, and a triangular shape.

[0121] FIG. 18B illustrates another exemplary second elongated member 1205 having a T-shaped cross section. In this example, the heating filament 1215 is embedded in notches 1301 in the second elongated member 1205 on each side of the vertical portion of the “T”. In some embodiments, the notches 1301 can be formed in the second elongated member 1205 during extrusion. Alternatively, the notches 1301 can be formed in the second elongated member 1205 after extrusion. For example, a cutting tool can form the notches in the second elongated member 1205. Preferably, the notches are formed by the heating filament 1215 as it is pushed or pulled (mechanically secured) into the second elongated member 1205 immediately after extrusion while the second elongated member 1205 is relatively soft. Alternatively, one or more heating filaments can be attached (e.g., glued, bonded, or partially embedded) to the bottom of the elongated member such that the filaments are exposed to the lumen of the tube. In such embodiments, it may be desirable to contain the filaments with insulation to reduce the risk of ignition when a flammable gas, such as oxygen, is passed through the lumen of the tube.

[0122] 18C illustrates in cross section yet another exemplary second elongate member 1205. The second elongate member 1205 has a generally triangular shape. In this example, heating filaments 1215 are embedded on either side of the triangle.

[0123] FIG. 18D illustrates yet another exemplary second elongated member 1205 in cross section. The second elongated member 1205 includes four grooves 1303. The grooves 1303 are depressions or indentations in the cross-sectional shape. In some embodiments, the grooves 1303 can facilitate the formation of a notch (not shown) for embedding a filament (not shown). In some embodiments, the grooves 1303 facilitate the positioning of a filament (not shown) so that the filament is pushed or pulled into the second elongated member 1205 and thereby embedded. In this example, the four starting grooves 1303 facilitate the placement of up to four filaments, e.g., four heating filaments, four sensing filaments, two heating filaments and two sensing filaments, three heating filaments and one sensing filament, or one heating filament and three sensing filaments. In some embodiments, the heating filaments can be located on the outside of the second elongated member 1205. The sensing filament can be located on the inside.

[0124] 18E illustrates in cross-section yet another exemplary second elongate member 1205. The second elongate member 1205 has a T-shaped cross-sectional shape and a number of grooves 1303 for positioning heating filaments.

[0125] FIG. 18F illustrates yet another exemplary second elongated member 1205 in cross section. Four filaments 1215 are encapsulated within the second elongated member 1205, two on each side of the vertical portion of the “T”. The filaments are encapsulated within the second elongated member 1205 because the second elongated member 1205 was extruded around the filaments, as described in more detail below. No notches were formed to embed the heating filaments 1215. In this example, the second elongated member 1205 also includes a number of grooves 1303. Because the heating filaments 1215 are encapsulated within the second elongated member 1205, the grooves 1303 are not used to facilitate the formation of notches to embed the heating filaments. In this example, the grooves 1303 can facilitate separation of the embedded heating filaments, which, for example, facilitates stripping of the individual cores when terminating the heating filaments.

[0126] 18G illustrates yet another exemplary second elongate member 1205 in cross section. The second elongate member 1205 has a generally triangular shape. In this example, the shape of the second elongate member 1205 is similar to that of FIG. 18C, but four filaments 1215 are encapsulated within the second elongate member 1205, all of which are centrally located in the lower third of the second elongate member 1205 and disposed along a generally horizontal axis.

[0127] As explained above, it may be desirable to increase the distance between the filaments to improve heating efficiency. However, in some embodiments, when the heating filament 1215 is incorporated into the composite pipe 1201, the filament 1215 may be positioned relatively centrally in the second elongated member 1205. The centralized location provides robustness to the composite piping for reuse, in part because such a location reduces the likelihood of the filament breaking during repeated bending of the composite pipe 1201. Centering the filament 1215 may also reduce the risk of fire hazards, since the filament 1215 is coated with a thermal barrier and away from the gas path.

[0128] As discussed above, some of the above examples show suitable arrangements of the filaments 1215 within the second elongated member 1205. In the aforementioned examples with multiple filaments 1215, the filaments 1215 are aligned generally along a horizontal axis. Alternative configurations are suitable. For example, two filaments could be aligned along a vertical axis or along a diagonal axis. Four filaments could be aligned along a vertical axis or along a diagonal axis. Four filaments could be aligned in a cross configuration, with one filament disposed at the top of the second elongated member, one filament disposed at the bottom of the second elongated member (near the lumen of the tube), and two filaments disposed at the left and right bars of a "T" or "Y" shape, or at the ends of the base of a triangle.

[0129] Tables 1A and 1B show some preferred dimensions of the medical tubing described herein, as well as some preferred ranges for these dimensions. The dimensions represent the transverse cross-section of the tubing. In these tables, lumen diameter represents the inner diameter of the tubing. Pitch represents the distance between two repeating points measured axially along the tubing, i.e., the distance between the tips of adjacent vertical portions of the "T" of the second elongated member. Bubble width represents the width (maximum outer diameter) of the bubble. Bubble height represents the height of the bubble from the lumen of the tubing. Bead height represents the maximum height of the second elongated member from the lumen of the tubing (e.g., the height of the vertical portion of the "T"). Bead width represents the maximum width of the second elongated member (e.g., the width of the horizontal portion of the "T"). Bubble thickness represents the thickness of the bubble wall.

[0130] [Table 1]

[0131] [Table 2]

[0132] Tables 2A and 2B provide exemplary ratios between dimensions of tube geometries for the tubes set forth in Tables 1A and 1B, respectively.

[0133] [Table 3]

[0134] [Table 4]

[0135] The following table shows some exemplary properties of a composite tubing (designated "A") having a heating filament embedded within the second elongated member as described herein. For comparison, properties of a Fisher & Paykel model RT100 disposable corrugated tubing (designated "B") having a heating filament helically wound within the bore of the tubing are also shown.

[0136] Resistance to flow (RTF) measurements were performed according to ISO5367:2000(E), Annex A. The results are summarized in Table 3. As can be seen below, the RTF for the composite pipe is less than the RTF for the model RT100 pipe.

[0137] [Table 5]

[0138] Condensation or "rainout" inside the tube represents the weight of condensate collected per day at a room temperature of 18°C ​​with a gas flow rate of 20 L / min. Humidified air is continuously flowed from the chamber through the tube. The weight of the tube is recorded before and after each day of testing. Three consecutive tests are performed, allowing the tube to dry between each test. The results are shown in Table 4. These results showed that rainout was significantly lower on the composite tube than on the model RT100 tube.

[0139] [Table 6]

[0140] The power requirements represent the power consumed during the condensation test. In this test, the ambient air was kept at 18°C. The humidification chamber (see, for example, humidification chamber 114 in FIG. 1) was powered by an MR850 heater base. A heating filament in the tube was powered separately from the DC power supply. Various flow rates were set and the chamber was maintained at 37°C at the chamber output. The DC voltage to the circuit was then changed to produce a temperature of 40°C at the circuit output. The voltage required to hold the output temperature was recorded and the resulting power was calculated. The results are shown in Table 5. These results show that composite tube A uses significantly more power than tube B. This is because tube B uses a helical heating filament within the tube bore to heat the gas from 37°C to 40°C. The composite tube does not tend to heat the gas as quickly because the heating filament is within the tube wall (embedded in the second elongated member). Rather, the composite tube is designed to hold the gas temperature and prevent rainout by keeping the tube bore at a temperature above the dew point of the humidified gas.

[0141] [Table 7]

[0142] The tubes were tested for flexibility using a three-point bend test. The tubes were placed in a three-point bend test jig and used with an Instron 5560 Test System instrument to measure load and elongation. Each tube sample was tested three times. The elongation of the tubes with respect to the applied load was measured to obtain an average stiffness constant for each. The average stiffness constants for Tube A and Tube B are shown in Table 6.

[0143] [Table 8]

[0144] As mentioned above, heated wires 206 can be placed inside the inspiratory limb 202 and / or expiratory limb 210 to keep the wall temperature above the dew point temperature, thereby reducing the risk of rainout within the tube.

[0145] thermal properties In embodiments of the composite tube 1201 incorporating a heating filament 1215, heat may be lost through the wall of the first elongated member 1203, resulting in uneven heating. As explained above, one method to compensate for these heat losses is to apply an external heating source at the wall of the first elongated member 1203, which helps to regulate the temperature and prevent heat loss. However, other methods for optimizing thermal properties may also be used.

[0146] Reference is now made to Figures 19A-19C, which illustrate example configurations for bubble height (i.e., the cross-sectional height of the first elongate member 1203 measured from the lumen-facing surface to the surface defining the maximum outer diameter) for improving thermal properties.

[0147] The dimensions of the bubbles can be selected to reduce heat loss from the composite tube 1201. In general, increasing the bubble height also increases the effective thermal resistance of the tube 1201 because a larger bubble height allows the first elongated member 1203 to hold more insulating air. However, it has been discovered that at some bubble height, changes in air density cause convection currents inside the tube 1201, thereby increasing heat loss. Also, at some bubble height, the surface area becomes so large that heat lost through the surface exceeds the benefit of a larger bubble height. Certain embodiments include these realizations.

[0148] The radius of curvature and the curvature of the bubble can be useful in determining the desired bubble height. The curvature of an object is defined as the inverse of the radius of curvature of the object. Thus, the greater the radius of curvature an object has, the less curved the object is. For example, a flat surface has an infinite radius of curvature and therefore a curvature of 0.

[0149] FIG. 19A shows a longitudinal cross section of the top of the composite tube. FIG. 19A shows one embodiment of the composite tube 1201 where the bubble has a large height. In this example, the bubble has a relatively small radius of curvature and therefore a large curvature. Also, the bubble is about 3-4 times as tall as the height of the second elongated member 1205.

[0150] Figure 19B shows a longitudinal cross section of the top of another composite tube. Figure 19B shows an embodiment of a composite tube 1201 where the bubble is flattened at the top. In this example, the bubble has a very large radius of curvature and a small curvature. Also, the bubble is about the same height as the second elongated member 1205.

[0151] FIG. 19C shows a longitudinal cross section of the top of another composite tube. FIG. 19C shows an embodiment of a composite tube 1201 where the width of the bubble is greater than the height of the bubble. In this example, the bubble has a radius and curvature between those of FIG. 19A and FIG. 19B, with the center of radius for the top of the bubble being on the outside of the bubble (as compared to FIG. 19A). The inflection points on the left and right sides of the bubble are approximately in the middle (heightwise) of the bubble (as opposed to being at the bottom of the bubble as in FIG. 19A). Also, the height of the bubble is approximately twice that of the second elongate member 1205, resulting in a bubble height between the heights of FIG. 19A and FIG. 19B.

[0152] The configuration of FIG. 19A had the least heat loss from the tubes. The configuration of FIG. 19B had the most heat loss from the tubes. The configuration of FIG. 19C had intermediate heat loss between the configurations of FIG. 19A and 19B. However, the large external surface area and convective heat transfer in the configuration of FIG. 19A resulted in inefficient heating. Thus, of the three bubble configurations of FIG. 19A-FIG. 19C, the configuration of FIG. 19C was determined to have the best overall thermal properties. With the same thermal energy input to the three tubes, the configuration of FIG. 19C produced the greatest temperature rise along the length of the tubes. The bubbles of FIG. 19C are large enough to increase the insulating air volume, but not so large as to cause significant heat loss by convection. The configuration of FIG. 19B was determined to have the worst thermal properties. That is, the configuration of FIG. 19B produced only the smallest temperature rise along the length of the tubes. The configuration of FIG. 19A had intermediate thermal properties and produced a lower temperature rise than the configuration of FIG. 19C.

[0153] It should be understood that while the configuration of FIG. 19C may be preferred in certain embodiments, other configurations, including the configuration of FIG. 19A, the configuration of FIG. 19B, and other variations, may be utilized in other embodiments, if desired.

[0154] Table 7 shows the bubble height, tube outer diameter, and radius of curvature for the configurations shown in Figures 19A, 19B, and 19C, respectively.

[0155] [Table 9]

[0156] 19C-19F, which show example positioning of heating elements 1215 in similar bubble shapes to improve thermal properties. The position of the heating elements 1215 can change the thermal properties of the interior of the composite tube 1201.

[0157] Figure 19C shows a longitudinal cross section of the top of another composite tube. Figure 19C shows an embodiment of a composite tube 1201 where the heating elements 1215 are centrally located within the second elongate member 1205. This example shows the heating elements 1215 close to each other but not close to the bubble wall.

[0158] Figure 19D shows a longitudinal cross section of the top of another composite tube. Figure 19D shows an embodiment of a composite tube 1201 in which the heating elements 1215 are positioned further apart within the second elongate member 1205 than in Figure 19C. These heating elements are closer to the bubble wall, allowing for better regulation of the heat inside the composite tube 1201.

[0159] Figure 19E shows a longitudinal cross section of the top of another composite tube. Figure 19E shows an embodiment of a composite tube 1201 in which heating elements 1215 are spaced above and below the vertical axis of the second elongate member 1205. In this example, the heating elements 1215 are equally close to each bubble wall.

[0160] Figure 19F shows a longitudinal cross section of the top of another composite tube. Figure 19F shows an embodiment of a composite tube 201 in which heating elements 1215 are spaced apart on either end of the second elongate member 1205. The heating elements 1215 are closer to the bubble wall, particularly in comparison to Figures 19C-19E.

[0161] Of the four filament configurations of Figures 19C-19F, Figure 19F was determined to have the best thermal properties. All configurations produced similar heat loss from the tube due to their similar bubble shape. However, when the same heat energy was input into the tube, the filament configuration of Figure 19F produced the greatest temperature rise along the length of the tube. The configuration of Figure 19D was determined to have the second best thermal properties, producing the second greatest temperature rise along the length of the tube. The configuration of Figure 19C produced the next best results. The configuration of Figure 19E had the worst performance, producing the smallest temperature rise along the length of the tube when the same amount of heat was input.

[0162] It should be understood that while the configuration of FIG. 19F may be preferred in certain embodiments, other configurations, including the configurations of FIGS. 19C, 19D, 19E, and other variations, may be utilized in other embodiments, if desired.

[0163] Reference is now made to Figures 20A-C, which show exemplary configurations for stacking the first elongated member 1203. In certain embodiments, it has been discovered that stacking multiple foam bodies can improve heat distribution. These embodiments may be more beneficial when using an internal heating filament 1215. Figure 20A shows a longitudinal cross section of the top of another composite tube. Figure 20A shows a cross section of the composite tube 1201 without stacking.

[0164] FIG. 20B shows a longitudinal cross section of the top of another composite tube. FIG. 20B shows another exemplary composite tube 1201 with stacked bubbles. In this example, two bubbles are stacked on top of each other to form a first elongated member 1203. Compared to FIG. 20A, the overall bubble height remains the same, but the bubble pitch is half that of FIG. 20A. Also, the embodiment in FIG. 20B has only a slight reduction in air volume. The stacking of bubbles reduces natural convection and heat transfer in the gaps between the bubbles 1213, lowering the overall thermal resistance. The heat flow path is increased within the stacked bubbles, allowing heat to be more easily distributed through the composite tube 1201.

[0165] FIG. 20C shows a longitudinal cross section of the top of another composite tube. FIG. 20C shows another example of a composite tube 1201 with stacked bubbles. In this example, three bubbles are stacked on top of each other to form a first elongated member 1203. Compared to FIG. 20A, the overall bubble height remains the same, but the bubble pitch is one third of that in FIG. 20A. Also, the embodiment in FIG. 20B has only a slight reduction in air volume. The stacking of bubbles reduces natural convection and heat transfer in the gaps between the bubbles 1213.

[0166] Exemplary embodiments Below is a numbered list of exemplary embodiments within the scope of this disclosure. The exemplary embodiments listed should not be construed as limiting the scope of the embodiments. Various features of the exemplary embodiments listed may be removed, added, or combined to form further embodiments, which are also part of this disclosure. 1. A medical tubing comprising a first section of medical tubing, the first section comprising: a first structure forming a conduit configured to transport a humidified gas; a first heater wire circuit; The medical tubing further comprises a second section of the medical tubing, the second section comprising: a second structure forming a conduit configured to transport the humidified gas; and a second heater wire circuit; the medical tubing further comprises an intermediate connector comprising a connection circuit electrically coupling the first heater wire circuit to the second heater wire circuit, the intermediate connector being coupled to a patient end of the first section of the medical tubing and a chamber end of the second section of the medical tubing to form a single conduit for the humidified gas; at least a portion of the intermediate connector is covered by a portion of the first section of the medical tubing and / or a portion of the second section of the medical tubing such that the intermediate connector is interior to the medical tubing; In a first mode, power passes through the connection circuit to provide power to the first heater wire circuit and not to the second heater wire circuit, and in a second mode, power passes through the connection circuit to provide power to both the first heater wire circuit and the second heater wire circuit. Medical tube. 2. The medical tube of embodiment 1, wherein the connection circuit comprises a diode. 3. The medical tube of embodiment 1 or 2, further comprising a first sensor positioned at the patient end of the first section. 4. The medical tube of embodiment 3, wherein the first sensor is one of a temperature sensor or a humidity sensor. 5. The medical tubing of any one of embodiments 1-4, further comprising a second sensor positioned at a patient end of the second section of the medical tubing. 6. The medical tube of embodiment 5, wherein the second sensor is one of a temperature sensor or a humidity sensor. 7. The first structure comprises an elongated tube, the elongated tube comprising: a first elongate member comprising a hollow body helically wound to at least partially define a conduit having a longitudinal axis, a lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen; a second elongate member helically wound and joined between adjacent turns of the first elongate member, the second elongate member forming at least a portion of the lumen of the elongate tube; The medical tube according to any one of embodiments 1 to 6, comprising: 8. The medical tubing of embodiment 7, wherein the first elongate member, in longitudinal cross-section, defines a plurality of bubbles having flattened surfaces in the lumen. 9. The medical tube of embodiment 8, wherein adjacent foam bodies are separated by gaps above the second elongate member. 10. The medical tubing of embodiment 8, wherein adjacent foam bodies are not directly connected to each other. 11. The medical tubing of embodiment 8, wherein the plurality of foam bodies have perforations. 12. An inspiratory limb comprising a first segment of the inspiratory limb having a first heater wire circuit, a second segment of the inspiratory limb having a second heater wire circuit, an intermediate connector having a connector circuit configured to electrically couple the first heater wire circuit to the second heater wire circuit, a first sensor positioned at a patient end of the first segment, and a second sensor positioned at a patient end of the second segment; Control device and A respiratory humidification system comprising: A controller is adapted to selectively switch between a first mode and a second mode, in which the controller provides power through the connector circuit to the first heater wire circuit, and in which the controller provides power to the first and second heater wire circuits. Respiratory humidification system. 13. The system of embodiment 12, wherein switching is based on input from one or both sensors. 14. The system of embodiment 13, wherein the input from one or both sensors includes one or more of temperature, flow rate, humidity, and power. 15. The system of any one of embodiments 12-14, wherein the first and second modes are defined by a direction of current provided by the power source. 16. A system in any one of embodiments 12 to 15, wherein the control device is adapted to selectively switch between a first sensor reading mode and a second sensor reading mode, and in the first sensor reading mode, the control device reads a signal from the second sensor, and in the second sensor reading mode, the control device reads signals from both the first sensor and the second sensor. 17. The system of any one of embodiments 12-16, wherein the first sensor and the second sensor are temperature sensors. 18. An inspiratory limb comprising a first segment of the inspiratory limb having a first heater wire circuit, a second segment of the inspiratory limb having a second heater wire circuit, an intermediate connector having a connector circuit configured to electrically couple the first heater wire circuit to the second heater wire circuit, a first sensor positioned at a patient end of the first segment, and a second sensor positioned at a patient end of the second segment; The expiratory limb, an interface connected to the inspiratory limb and the expiratory limb; Control device and A dual limb circuit comprising: A controller is adapted to selectively switch between a first mode and a second mode, in which the controller provides power through the connector circuit to the first heater wire circuit, and in which the controller provides power to the first and second heater wire circuits. Double limb circuit. 19. The dual limb circuit of embodiment 18, in which the expiratory limb comprises an expiratory heater wire circuit. 20. The dual limb circuit of embodiment 19, in which the expiratory limb is heated using an expiratory heater wire circuit. 21. The dual limb circuit of embodiment 19, wherein the expiratory heater wire circuit is powered in parallel with a first heater wire circuit in a first section of the inspiratory limb. 22. The dual limb circuit of embodiment 21, wherein the breath heater wire circuit can be configured to be powered in only the first mode, only the second mode, or in both the first and second modes. 23. The dual-limb circuit of any one of embodiments 18-22, wherein the interfaces are connected via a Y-piece. 24. A segmented inspiratory limb configured to be heated along at least two segments, each segment of the inspiratory limb comprising: a first elongate member comprising a hollow body helically wound to at least partially form an elongate tube having a longitudinal axis, a lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen; a second elongate member helically wound and joined between adjacent turns of the first elongate member, the second elongate member forming at least a portion of the lumen of the elongate tube; A segmented inspiratory limb comprising: 25. Medical tubing having two sections, each section having: an elongated hollow body spirally wound to form an elongated tube having a longitudinal axis, a lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen, the elongated hollow body having a wall that, in transverse cross section, defines at least a portion of the hollow body; a reinforcing portion extending along the length of the elongated hollow body, the reinforcing portion being helically positioned between adjacent turns of the elongated hollow body, the reinforcing portion forming a portion of the lumen of the elongated tube; and one or more conductive filaments embedded or encapsulated within the reinforcing portion. Equipped with The reinforcement is relatively thicker or stiffer than the wall of the hollow body; The medical tubing further comprises a segment connector attached to the first segment, the segment connector comprising: a connection pad configured to electrically couple a conductive filament from the first section to a conductive filament from the second section when the first section is physically coupled to the second section; a power diode electrically coupled to the conductive filament of the first section; Equipped with a power diode, when provided with an electrical signal of a first polarity, for transmitting power to the conductive filaments of the first section and for preventing transmission of power to the conductive filaments of the second section; A power diode provides power to the conductive filaments of the first section and the conductive filaments of the second section when provided with an electrical signal of the second polarity. Medical tube. 26. A first heater wire input connection configured to be electrically coupled to a first input heater wire; a second heater wire input connection configured to be electrically coupled to the second input heater wire; a first heater wire output connection electrically coupled to the first output heater wire and configured to be electrically coupled to the first heater wire input connection; a second heater wire output connection electrically coupled to the second output heater wire and configured to be electrically coupled to the second heater wire input connection; a first signal wire input connection configured to be electrically coupled to the first input signal wire; a second signal wire input connection configured to be electrically coupled to the second input signal wire; a first signal wire output connection electrically coupled to the first output signal wire and configured to be electrically coupled to the first signal wire input connection; a second signal wire output connection electrically coupled to the second input signal wire and configured to be electrically coupled to the second signal wire input connection; a power diode electrically coupled to the first heater wire input connection and the second heater wire input connection, the power diode configured to allow current to flow from the second input heater wire to the first input heater wire and to prevent current from flowing from the first input heater wire to the second input heater wire; a sensor electrically coupled to the first signal wire input connection; a signal diode electrically coupled to the sensor and the second signal wire input connection, the signal diode allowing current to flow from the second input signal wire through the sensor to the first input signal wire and preventing current from flowing from the first input signal wire through the sensor to the second input signal wire; A connector comprising:

[0167] conclusion Several examples of respiratory humidification systems and methods with dual-zone heating control and related components have been described with reference to the figures. The figures show various systems and modules and 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 the figures are presented to clearly show the principles associated with providing dual-zone heating control. Details regarding the division of modules or systems are provided for ease of explanation without attempting to define individual physical embodiments. The examples and figures are intended to illustrate, but not limit, the scope of the inventions described herein. For example, the principles herein can be applied to respiratory humidifiers, as well as other types of humidification systems, including surgical humidifiers. The principles herein can be applied in respiratory applications, as well as other scenarios in which the temperature of a gas is controlled along multiple sections exposed to different ambient temperatures.

[0168] As used herein, the term "processor" broadly refers to any suitable device, logic block, module, circuit, or combination of elements for executing instructions. For example, the controller 122 may include any conventional general-purpose single-chip or multi-chip microprocessor, such as a Pentium® processor, a MIPS® processor, a PowerPC® processor, an AMD® processor, an ARM® processor, or an ALPHA® processor. Additionally, the controller 122 may include any conventional special-purpose microprocessor, such as a digital signal processor or a microcontroller. The various exemplary logic blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed using a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein, or may be pure software within a main processor. For example, the logic module 504 may be a software-implemented functional block that does not utilize additional and / or specialized hardware elements. The controller 122 may be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a combination of a microcontroller and a microprocessor, multiple microprocessors, one or more microprocessors in association with a DSP core, or any other such configuration.

[0169] The data storage device may represent electronic circuitry that allows the processing device to store and retrieve data. The data storage device may represent an external device or system, such as a disk drive or solid-state drive. The data storage device may also represent high-speed semiconductor memory devices (chips), such as random access memory (RAM) or various forms of read-only memory (ROM), which are connected to the communication bus or directly to the control device 122. Other types of data storage devices include bubble memory and core memory. The data storage device may be physical hardware configured to store data in a non-transitory medium.

[0170] Although specific embodiments and examples are disclosed herein, the subject matter of the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and / or applications, as well as modifications and equivalents thereof. Thus, the scope of the claims or embodiments appended hereto is not limited by any of the specific embodiments described herein. For example, in any method or process disclosed herein, the acts or operations of the method or process can be performed in any suitable order and are not necessarily limited to any particular disclosed order. Various operations may be described in sequence as multiple separate operations, which may aid in understanding a particular embodiment. However, the order of description should not be construed to imply that these operations are ordered. Furthermore, structures described herein may be embodied as integrated components or as separate components. In order to compare various embodiments, specific aspects and advantages of these embodiments are described. Not all such aspects or advantages are necessarily realized by any particular embodiment. Thus, for example, various embodiments may be implemented to achieve or optimize one advantage or combination of advantages taught herein, without necessarily achieving other aspects or advantages that may also be taught or suggested herein.

[0171] As used herein, conditional expressions, such as "can," "may," "for example," and the like, among others, are generally intended to indicate that a particular embodiment includes a particular feature, element, and / or condition and that other embodiments do not include the particular feature, element, and / or condition, unless otherwise specified or contradicted by the context in which it is used. Thus, such conditional expressions are generally not intended to imply that a feature, element, and / or condition is essential to one or more embodiments. As used herein, the terms "comprise," "include," "have," or any other variant thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that includes a list of elements is not necessarily limited to only those elements, but may include other elements not expressly listed or that are inherent to such process, method, article, or apparatus. Additionally, the term "or" is used in its inclusive sense (rather than its exclusive sense), and thus, for example, when used to join a list of elements, the term "or" means one, some, or all of the elements in the list. Disjunctive phrases such as "at least one of X, Y, and Z" generally indicate that an element, term, etc. may be X, Y, or Z, unless otherwise stated or contradicted by the context in which it is used. Thus, such disjunctive phrases are not intended to suggest that at least one of X, at least one of Y, and at least one of Z, respectively, must be present in a particular embodiment. As used herein, the words "about" or "approximately" can mean that a value is within ±10%, within ±5%, or within ±1% of the specified value.

[0172] The methods and processes described herein may be embodied in software code modules executed by one or more general-purpose and / or special-purpose computers and may be partially or fully automated by such software code modules. The term "module" refers to logic embodied in hardware and / or software, or to a collection of software instructions, which may have entry and exit points, written in a programming language, such as, for example, C or C++. Software modules may be compiled and linked into executable programs installed in a dynamically linked library, or may be written in an interpreted programming language, such as, for example, BASIC, Perl, or Python. It is understood that software modules may be callable from other modules or themselves, and / or may be called in response to a detected event or interrupt. Software instructions may be embedded in firmware, such as an erasable programmable read-only memory (EPROM). Hardware modules may include connected logic units, such as gates and flip-flops, and / or may include 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. Further, in some embodiments, the modules may be separately compiled, while in other embodiments, the modules may represent a subset of a separately compiled program's instructions and may not have an interface available to other logical program units.

[0173] In particular embodiments, the code modules may be implemented and / or stored on 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 a relational database and / or a flat file system. Any of the systems, methods, and processes described herein may include an interface configured to enable interaction with a user, operator, other systems, components, programs, etc.

[0174] It is emphasized that many variations and modifications can be made to the embodiments described herein, and that these elements should be understood to be included in other acceptable embodiments. All such modifications and variations are intended to be within the scope of this disclosure and protected by the accompanying claims. Moreover, nothing in the above disclosure is intended to imply that any particular component, feature, or process step is required or essential.

Claims

1. A connector for connecting sections of medical tubing in a respiratory circuit, said connector comprising: a first connection circuit configured to be electrically coupled to one or more first heating wires, the first connection circuit and the one or more first heating wires forming a first heating wire loop; the first connection circuit is further configured to be electrically coupled to one or more second heating wires, the first connection circuit, the one or more first heating wires, and the one or more second heating wires forming a second heating wire loop; a second connection circuit configured to be electrically coupled to the one or more first sensor wires and the one or more second sensor wires; a first diode electrically coupled to the first connection circuit, the first diode configured to allow current to flow through the first heating wire loop in a first direction and to block current to flow through the first heating wire loop in a second direction; A connector comprising:

2. Further comprising a second diode electrically coupled to the first connection circuit; 2. The connector of claim 1, wherein the second diode is configured to allow current to flow through the second heating wire loop in the second direction and to block current to flow through the second heating wire loop in the first direction.

3. A connector as described in claim 1 or 2, characterized in that the first diode is a power diode.

4. The second connection circuit and the one or more first sensor wires form a first sensor wire loop; the second connection circuit, the one or more first sensor wires, and the one or more second sensor wires form a second wire loop, the connector further comprising: a first sensor electrically coupled to the second connection circuit, the first sensor forming a part of the first sensor wire loop; a third diode electrically coupled to the first sensor and the second connecting circuit, the third diode configured to allow current to flow through the first sensor wire loop in the first direction and to block current to flow through the first sensor wire loop in the second direction; and 4. The connector according to claim 1, further comprising:

5. A connector as described in any one of claims 1 to 4, characterized in that the connector is electrically coupled to a power source, and one or more switches are disposed between the power source and the connector.

6. A connector as described in claim 4 or 5, further comprising a second sensor electrically coupled to the second connection circuit, the second sensor forming part of the second sensor wire loop.

7. Further comprising a fourth diode electrically coupled to the second sensor and the second connection circuit; 7. The connector of claim 6, wherein the fourth diode is configured to allow current to flow through the second sensor wire loop in the second direction and to block current to flow through the second sensor wire loop in the first direction.

8. A connector as described in claim 6 or 7, characterized in that the third diode is a signal diode, or the third diode and the fourth diode are signal diodes.

9. A connector as described in any one of claims 6 to 8, characterized in that the first sensor and the second sensor are thermistors or transistors configured to measure temperature.

10. A connector as described in any one of claims 6 to 9, characterized in that the first sensor and the second sensor are digital temperature sensors, each of the digital temperature sensors having a single line for communication and power.

11. A connector as described in any one of claims 1 to 10, characterized in that the one or more first sensor wires and / or the one or more second sensor wires are connected to one of a temperature sensor, a flow sensor, an oxygen sensor, or a humidity sensor.

12. A connector as described in any one of claims 4 to 11, characterized in that the first sensor is spaced apart from other active and passive electrical components.

13. The connector of claim 12, wherein the first sensor is disposed on a protrusion of the connector.

14. A connector as described in any one of claims 1 to 13, characterized in that it is configured to mechanically and electrically connect two sections of the medical tubing within a breathing circuit.

15. A connector as described in claim 14, characterized in that the connector is positioned inside the medical tubing and has an aerodynamic cross-section to reduce turbulence of gas flowing through the medical tubing.

16. A connector as described in any one of claims 1 to 15, further comprising a printed circuit board (PCB).

17. The connector described in Claim 16, characterized in that the PCB has connection pads for each of the one or more first heating wires and the one or more second heating wires, and the one or more first sensor wires and the one or more second sensor wires.

18. A connector as claimed in any preceding claim, characterized in that it is provided with a microcontroller.

19. A connector as described in claim 18, when at least dependent on claim 4, characterized in that the ratio of power supplied to the first heated wire loop and the second heated wire loop is continuously varied by the microcontroller based on feedback from the first sensor and / or the second sensor.

20. A connector as described in any one of claims 1 to 17, characterized in that it is controlled by a controller located in a humidification unit connected to the connector.

21. A connector as described in claim 20, when at least dependent on claim 4, characterized in that the ratio of power supplied to the first heated wire loop and the second heated wire loop is continuously varied by a controller based on feedback from the first sensor and / or the second sensor.

22. A connector as described in any one of claims 1 to 21, further comprising a placement limiter.

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