Area heating for breathing circuits

Abstract

To provide a medical device related to heating of gas in a respiration circuit used together with a humidification system.SOLUTION: Some embodiments provide an inspiratory limb for a breathing circuit that includes a first segment 202a that comprises a first heater wire circuit and a second segment 202b that comprises 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 to a second heater wire circuit. The inspiratory limb can be configured to operate in two modes wherein, in a first mode, electrical power passes through the first electrical connection to provide power to the first heater wire circuit without providing power to the second heater wire circuit, and in a second mode, electrical power pass through the first electrical connection to provide 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 claims priority to and relates to U.S. Provisional Patent Application No. 61 / 726,532 entitled "ZONE HEATING FOR RESPIRATORY CIRCUITS" filed on November 14, 2012; U.S. Provisional Patent Application No. 61 / 786,141 entitled "ZONE HEATING FOR RESPIRATORY CIRCUITS" filed on March 14, 2013; U.S. Provisional Patent Application No. 61 / 877,736 entitled "ZONE HEATING FOR RESPIRATORY CIRCUITS" filed on September 13, 2013; U.S. Provisional Patent Application No. 61 / 877,784 entitled "CONNECTIONS FOR HUMIDICATION SYSTEM" filed on September 13, 2013; U.S. Provisional Patent Application No. 61 / 877,622 entitled "MEDICAL TUBES AND METHODS OF MANUFACTURE" filed on September 13, 2013; U.S. Provisional Patent Application No. 61 / 877,566 entitled "HUMIDIFICATION SYSTEM" filed on September 13, 2013; and U.S. Provisional Patent Application No. 62 / 216,232 entitled "ZONE HEATING FOR RESPIRATORY CIRCUITS" filed on September 9, 2015; and U.S. Provisional Patent Application No. 62 / 380,195 entitled "ZONE HEATING FOR RESPIRATORY CIRCUITS" filed on August 26, 2016, each of which is hereby incorporated herein by reference in its entirety.

[0002] In addition, PCT application PCT / IB2012 / 001786, titled "MEDICAL TUBES AND METHODS OF MANUFACTURE," filed on 30 May 2012; PCT application PCT / NZ2013 / 000222, titled "MEDICAL TUBES AND METHODS OF MANUFACTURE," filed on 4 December 2013; and PCT application PCT / NZ2013 / 000208, titled "ZONE HEATING FOR RESPIRATORY CIRCUITS," filed on 14 November 2013, are also incorporated herein by reference in their entirety.

[0003] This disclosure relates in general to a humidification system for providing a humidifying gas to a user, and more particularly to the heating of a gas in a breathing circuit used in conjunction with the humidification system. [Background technology]

[0004] Many gas humidification systems deliver heated and humidified gas for various medical procedures, including respiratory therapy and laparoscopy. These systems can be configured to control temperature, humidity, and flow rate using feedback from sensors. To maintain desired characteristics when delivered to the user, the breathing circuit may 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 reaches the user with desired characteristics such as temperature and / or humidity. The humidification system may include a temperature sensor that provides feedback to a humidification control device, which can adjust and / or change the power supplied to the line heater to achieve a target temperature at a location along the associated line. [Overview of the Initiative] [Means for solving the problem]

[0005] The systems, methods, and devices described herein have innovative aspects, and none of these aspects are essential, nor do they represent only desirable attributes. Without limiting the scope of the claims, some of the advantageous features are summarized below.

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

[0007] The inspiratory limb may include a first segment of the inspiratory limb having a first structure that forms a conduit configured for transporting a humidifying gas, the first segment of the inspiratory limb including a first heater wire circuit. The inspiratory limb may include a second segment of the inspiratory limb having a second structure that forms a conduit configured for transporting a humidifying gas, the second structure being configured to be mechanically coupled to the first structure of the first segment to form an extended conduit for the humidifying gas, the second segment of the inspiratory limb including a second heater wire circuit. The inspiratory limb may include an intermediate connector that includes a connection circuit that electrically couples the first heater wire circuit to the second heater wire circuit, the intermediate connector being coupled to the patient end of the first segment of the inspiratory limb and the chamber end of the second segment of the inspiratory limb to form a single conduit for the humidifying gas. The intermediate connector can 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, so as to be located inside the inspiratory limb.

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

[0009] Several embodiments provide a respiratory humidification system comprising an inspiratory limb and a control device. 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 the patient end of the first segment, and a second sensor positioned at the patient end of the second segment. The control device can be adapted to selectively switch between a first mode and a second mode, in which case the control device provides power to the first heater wire circuit through the connector circuit, and in which case the control device 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 inputs 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 can be directly derived or obtained 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 the current or the polarity of the voltage provided by the power supply. In some embodiments, the respiratory humidification system may include three or more sensors, which provide inputs used to control the heating of the inspiratory limbs.

[0010] Several embodiments provide a dual-limb circuit that may include an inspiratory limb. Such an inspiratory limb may 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 the patient end of the first segment, and a second sensor positioned at the patient end of the second segment. The dual-limb circuit may also include an expiratory limb having an expiratory heater wire circuit. The dual-limb system may further include interfaces connected to the inspiratory and expiratory limbs. The dual-limb system may further include a control device adapted to selectively switch between a first mode and a second mode, in which the control device provides power to the first heater wire circuit through the connector circuit, and in which the control device provides power to the first and second heater wire circuits. In certain embodiments, heating of the expiratory limb is performed using an expiratory heater wire circuit, separately from heating of the inspiratory limb using 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 the first mode only, the second mode only, or both the first and second modes. In certain embodiments, the interface is 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 conventional sense to those skilled in the art (i.e., not limited to any particular or specialized sense), and includes, but is 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, the structure of which the segment comprises an elongated tube. The elongated tube may include a first elongated member comprising a hollow body spirally wound to form at least a portion of a conduit having a longitudinal axis, a lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen. The elongated tube may include a second elongated member spirally 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 cells in the lumen having a flattened surface in longitudinal cross-section. In certain implementations, adjacent cells are separated by a gap above the second elongated member. In certain implementations, adjacent cells are not directly connected to one another. In certain implementations, the plurality of cells have perforations.

[0012] Several embodiments provide a respiratory humidification system comprising two control circuits. The respiratory humidification system may include an inspiratory limb comprising a first section comprising a first heater wire and a second section comprising a second heater wire. The respiratory humidification system may also include a sensor positioned at the patient end of the second section to measure patient end parameters. The first and second heater wires are electrically coupled, with the first heater wire forming a first heater circuit and the first and second wires forming a second heater circuit. The respiratory humidification system may include a hardware control device configured to receive the sensor output. The hardware control device may be further configured to provide power to the first heater circuit when the difference between the sensor output and the patient end parameter setpoint is less than a predetermined threshold, and to provide power to the second heater circuit when the difference between the sensor output and the patient end parameter setpoint is greater than or equal to a predetermined threshold. The hardware control device may be configured to provide maximum power to the first heater circuit when the hardware control device provides power to the first heater circuit. In some embodiments, the respiratory humidification system may further include an intermediate connector having a connector circuit configured to electrically connect first and second heater wires. In some embodiments, the patient end parameter may be temperature. In some embodiments, the first and second heater wires may be exposed to different ambient environments. In some embodiments, the first and second heater wires may be exposed to different ambient temperatures. In some embodiments, the power supplied to the first and / or second heater circuits may be determined by a PID control scheme.

[0013] Several embodiments provide a respiratory humidification system comprising two control circuits. The respiratory humidification system may include an inspiratory limb comprising a first section comprising a first heater wire, a second section comprising a second heater wire, and a temperature sensor positioned at the patient end of the second section for measuring patient end parameters. The first and second heater wires can be electrically coupled, the first heater wire forming a first heater circuit, and the first and second wires forming a second heater circuit, and the first and second heater wires are configured to heat the respiratory gas passing through the inspiratory limb. The respiratory humidification system may include a flow sensor located in the system's flow path and configured to measure the flow rate of the respiratory gas. The respiratory humidification system may include a hardware processor that electrically communicates with the first and second heater wires, as well as the temperature sensor and the flow sensor. The hardware processor may be configured to execute software instructions that cause the processor to control the first and second heater circuits. The processor may be configured to heat the breathing gas using a first heater circuit until the first heater wire reaches a maximum temperature when the difference between the sensor output and the patient-end parameter setpoint is less than a predetermined error threshold. The processor may be configured to heat the breathing gas using a second heater circuit when the difference between the sensor output and the patient-end parameter setpoint is greater than or equal to a predetermined error threshold. The maximum power supplied to the first heater circuit may be a first maximum or a second maximum based on the flow rate, with the first maximum being higher than the second maximum.

[0014] In some embodiments, the maximum power may be a first maximum value when the measured flow rate is higher than the flow rate threshold, and a second maximum value when the measured flow rate is lower than the flow rate threshold. In some embodiments, the flow rate threshold may be about 2.4 lpm to about 5 lpm. In some embodiments, the flow rate threshold may be about 3.5 lpm. In some embodiments, the flow rate threshold may be about 3 lpm.

[0015] In other embodiments, a first maximum power is supplied to the first heater circuit, and when the measured flow rate decreases to a high-flow-low-flow threshold, the maximum power supplied to the first heater circuit can switch to a second maximum power. A second maximum power is supplied to the first heater circuit, and when the flow rate increases to a low-flow-high-flow threshold, the maximum power supplied to the first heater circuit can switch to the first maximum power, where the high-flow-low-flow threshold is lower than the low-flow-high-flow threshold. In some embodiments, the high-flow-low-flow threshold may be about 2.4 lpm to about 5 lpm. In some embodiments, the low-flow-high-flow threshold is about 6.5 lpm.

[0016] In some embodiments using a flow sensor, a portion of the first section of the inspiratory limb adjacent to the second section can be exposed to the same ambient environment as the second section. In some embodiments, a portion of the first section and the second section may be inside the incubator, while the remaining portion of the first section may be outside the incubator.

[0017] Reference numerals may be used repeatedly throughout the drawings to illustrate the general correspondence between reference elements. The drawings are provided to illustrate exemplary embodiments described herein and are not intended to limit the scope of this disclosure. [Brief explanation of the drawing]

[0018] [Figure 1] A diagram illustrating an exemplary respiratory humidification system for supplying humidifying gas to a user, wherein the respiratory humidification system has a breathing circuit, and the breathing circuit includes a segmented inspiratory limb having sensors in each section. [Figure 2] This figure shows a segmented intake arm for use with a humidification system, which has an intermediate connector configured to connect a heater wire and a sensor in two segments. [Figure 3A]It is an exemplary circuit diagram including an active rectification power supply for supplying power to heater wires within a segmented inspiratory limb of a breathing circuit, wherein the circuit is configured to supply power to the heater wire within a first segment of the inspiratory limb in a first mode, and supply power to the heater wires within both segments in a second mode. [Figure 3B] It is an exemplary circuit diagram including an active rectification power supply for supplying power to heater wires within a segmented inspiratory limb of a breathing circuit, wherein the circuit is configured to supply power to the heater wire within a first segment of the inspiratory limb in a first mode, and supply power to the heater wires within both segments in a second mode. [Figure 4A] It is a diagram showing an exemplary humidification system having an inspiratory limb and an expiratory limb, wherein the humidification system is configured to control heater wires in both limbs. [Figure 4B] It is a diagram showing an exemplary humidification system having an inspiratory limb and an expiratory limb, wherein the humidification system is configured to control heater wires in both limbs. [Figure 4C] It is a diagram showing an exemplary humidification system having an inspiratory limb and an expiratory limb, wherein the humidification system is configured to control heater wires in both limbs. [Figure 4D] It is a diagram showing an exemplary humidification system having an inspiratory limb and an expiratory limb, wherein the humidification system is configured to control heater wires in both limbs. [Figure 5] It is a block diagram of an exemplary system configured to detect the presence of an extension of an inspiratory limb, and supply power to heater wires in the inspiratory limb, the extension of the inspiratory limb, and the expiratory limb. [Figure 6A] It is an exemplary circuit diagram in a humidification system, wherein the circuit is configured to read data from two sensors. [Figure 6B] It is an exemplary circuit diagram in a humidification system, wherein the circuit is configured to read data from two sensors. [Figure 7]It is an exemplary circuit diagram in a humidification system, wherein the circuit is configured to read temperature data using two transistors. [Figure 8A] It is an exemplary diagram of a hardware configuration for a breathing circuit including an inspiratory limb and an expiratory limb, wherein the inspiratory limb has a first section and a second section. [Figure 8B] It is an exemplary diagram of a hardware configuration for a breathing circuit including an inspiratory limb and an expiratory limb, wherein the inspiratory limb has a first section and a second section. [Figure 9] It is a diagram illustrating an exemplary embodiment of a respiratory humidification system that uses a microcontroller provided in an intermediate connector to measure data for controlling heating and read sensor values in the inspiratory limb. [Figure 10] It is a block diagram of an intermediate connector for an inspiratory limb, wherein the intermediate connector uses a microcontroller. [Figure 11] It is a circuit diagram of an exemplary power module and a data line converter included in the intermediate connector shown in FIG. 10. [Figure 12] It 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 a control side and an AC side on a circuit board. [Figure 13] It is a circuit diagram of an exemplary humidification system incorporating a digital temperature sensor for use with a breathing circuit having an inspiratory limb comprising at least two sections. [Figure 14A] It is a diagram illustrating an exemplary printed circuit board ("PCB") of an intermediate connector. [Figure 14B] It is a diagram illustrating an exemplary printed circuit board ("PCB") of an intermediate connector. [Figure 14C] It is a diagram illustrating an exemplary embodiment of an intermediate connector. [Figure 14D] It is a diagram illustrating an exemplary embodiment of an intermediate connector. [Figure 15A] It is a diagram illustrating an exemplary PCB for a patient end connector. [Figure 15B]This figure shows an exemplary embodiment of a patient end connector. [Figure 15C] This figure shows an exemplary embodiment of a patient end connector. [Figure 15D] This figure shows an exemplary embodiment of a patient end connector. [Figure 15E] This figure shows an exemplary embodiment of a patient end connector. [Figure 16A] This figure shows an exemplary embodiment of a placement limiter for segmented inspiratory limbs. [Figure 16B] This figure shows an exemplary embodiment of a placement limiter for segmented inspiratory limbs. [Figure 16C] This figure shows an exemplary embodiment of a placement limiter for segmented inspiratory limbs. [Figure 16D] This figure shows an exemplary embodiment of a placement limiter for segmented inspiratory limbs. [Figure 16E] This figure shows an exemplary embodiment of a placement limiter for segmented inspiratory limbs. [Figure 17A] This is a side view of a section of an exemplary composite pipe. [Figure 17B] This is a longitudinal cross-sectional view of the upper part of a pipe similar to the example composite pipe shown in Figure 17A. [Figure 17C] This is another longitudinal cross-sectional view showing the first elongated member inside the composite pipe. [Figure 17D] This is another longitudinal cross-section of the top of the pipe. [Figure 17E] This is another longitudinal cross-section of the top of the pipe. [Figure 18A] This is a cross-sectional view of the second elongated member inside the composite pipe. [Figure 18B] This is another cross-sectional view of the second elongated member. [Figure 18C] This figure shows a second elongated member as another example. [Figure 18D] This figure shows a second elongated member as another example. [Figure 18E] This figure shows a second elongated member as another example. [Figure 18F]This figure shows a second elongated member as another example. [Figure 18G] This figure shows a second elongated member as another example. [Figure 19A] This figure shows an example of the shape of a first elongated member configured to improve thermal efficiency. [Figure 19B] This figure shows an example of the shape of a first elongated member configured to improve thermal efficiency. [Figure 19C] This figure shows an example of the shape of a first elongated member configured to improve thermal efficiency. [Figure 19D] This figure shows an example of a filament configuration designed to improve thermal efficiency. [Figure 19E] This figure shows an example of a filament configuration designed to improve thermal efficiency. [Figure 19F] This figure shows an example of a filament configuration designed to improve thermal efficiency. [Figure 20A] This figure shows an example of lamination of the first elongated member. [Figure 20B] This figure shows an example of lamination of the first elongated member. [Figure 20C] This figure shows an example of lamination of the first elongated member. [Figure 21A] This is an exemplary circuit diagram configured to control two heaters independently. [Figure 21B] This is an exemplary circuit diagram configured to control the gates of two heaters. [Figure 21C] This is an exemplary circuit diagram configured to switch between independent control of two heaters and gate control. [Figure 22A] This is an illustrative circuit diagram including a logic module and mode relay configured to enable control of two or partitioned heaters. [Figure 22B] This is a block diagram of a mode relay configured to control two heaters. [Figure 22C] This is a block diagram of a mode relay configured to control a segmented heater. [Figure 23] This is an exemplary circuit diagram configured to switch between independent control of two heaters and gate control of two heaters, and to provide the functionality described with respect to the exemplary circuit diagram shown in Figure 22A. [Figure 24A] This is an exemplary circuit diagram configured to control two heaters in parallel. [Figure 24B] Figure 24A shows an exemplary configuration of a heater module in which both heaters include diodes to control the flow of current. [Figure 24C] Figure 24A shows an exemplary circuit diagram configured to control a segmented heater by using a heater module. [Figure 24D] Figure 24C shows an exemplary configuration of the heater module. [Figure 25A] This is another exemplary circuit diagram configured to control two heaters in parallel using an active rectifier circuit. [Figure 25B] This is another exemplary circuit diagram configured to control two heaters in parallel using an active rectifier circuit. [Figure 25C] This is another exemplary circuit diagram configured to control two heaters in parallel using an active rectifier circuit. [Figure 26] This is a flowchart illustrating an exemplary method for controlling a segmented heater. [Figure 27] This is a diagram showing the target temperature profile. [Figure 28] This is a functional block diagram showing the relationship between the processing components of the control module, the demand related to the heater section, and the application of the control module's determination. [Figure 29] This is a flowchart of an exemplary control algorithm. [Figure 30] This is an exemplary flowchart of a PID control scheme. [Figure 31] This is a flowchart of another exemplary control algorithm. [Figure 32A] This diagram shows an example of an intermediate connector. [Figure 32B] This diagram shows an example of an intermediate connector. [Figure 32C] This diagram shows an example of an intermediate connector. [Figure 33A] This figure shows an example cover for an intermediate connector. [Figure 33B] This figure shows an example cover for an intermediate connector. [Figure 33C] This figure shows an example cover for an intermediate connector. [Figure 34] This figure shows exemplary embodiments of intake and extension limbs, each comprising a diode and a heater wire directly coupled to each other. [Figure 35] This is a flowchart of another exemplary control algorithm. [Figure 36] This is a flowchart of another exemplary control algorithm. [Figure 37] Here is another exemplary flowchart of a PID control scheme. [Figure 38] This figure shows another exemplary embodiment of an intake duct for use with a humidification system. [Figure 39A] This figure shows an exemplary configuration of the inspiratory limbs and extension limbs for an incubator. [Figure 39B] This figure shows an exemplary configuration of the inspiratory limbs and extension limbs for an incubator. [Figure 40] This is a flowchart of another exemplary control algorithm with low-flow control components. [Figure 41] This is a flowchart of another exemplary low-flow control component. [Figure 42] This figure shows another example PCB of an intermediate connector. [Figure 43] This figure shows another example PCB of a patient end connector. [Figure 44A] This figure shows an example PCB of a chamber end connector. [Figure 44B] This figure shows an example PCB of a chamber end connector. [Modes for carrying out the invention]

[0019] This specification describes specific embodiments and examples of segmented inspiratory limbs, multi-zone heating, and heating of the inspiratory and / or expiratory limbs. Those skilled in the art will understand that this disclosure also encompasses the embodiments and / or uses specifically disclosed, as well as their obvious modifications and equivalents. Accordingly, the scope of this disclosure as disclosed herein is not intended to be limited by any specific embodiment described herein.

[0020] This specification describes systems and methods for providing heat to a segmented inspiratory limb or to an inspiratory and / or expiratory limb within a respiratory circuit of a respiratory humidification system. While most of the descriptions herein are in the context of segmented inspiratory and / or expiratory limbs within a respiratory circuit, it should be understood that one or more features of this disclosure may also be realized in other scenarios where it is desirable to provide differentiated heating or independent heating of separate gas delivery lines within segmented gas delivery lines in, for example, respiratory, surgical, or other applications.

[0021] This disclosure refers to heater wires, heating elements, and / or heaters in the context of providing heat to conduits. For example, heater wire is a broad term and should be interpreted in its usual and customary sense to those skilled in the art (i.e., not limited to any particular or specialized sense), and includes, but is not limited to, heater strips and / or heat transfer elements that generate heat when power is supplied. Examples of such heating elements include wires formed from conductive metals (e.g., copper), conductive polymers, conductive inks printed on the surface of a conduit, conductive materials used to create tracks in a conduit, etc. Furthermore, this disclosure refers to conduits, limbs, and medical conduits in the context of gas delivery. For example, conduit is a broad term and should be interpreted in its usual and customary sense to those skilled in the art, and includes, but is not limited to, conduits having various cross-sections, such as cylindrical and non-cylindrical paths. Certain embodiments may incorporate composite conduits, which can generally be defined as conduits comprising two or more parts or, in particular in some embodiments, two or more components, as described in more detail below. The segmented limbs equipped with the disclosed medical tubes may also be used in respiratory circuits such as continuous, variable, or bilevel positive airway pressure (PAP) systems, or in other forms of respiratory therapy. The terms “tube” and “limb” should be interpreted as being synonymous with “tube.”

[0022] When a heated and humidified breathing tube is used for an incubator or a temperature-controlled environment (or any area with temperature variations, such as around a radiant heater used for burn patients or under a blanket used by a patient), the breathing tube passes through at least two distinct regions: a low-temperature region (such as the region outside the incubator) and a high-temperature region (such as the region inside the incubator). If the tube is heated by a single heater along its entire length, depending on which region is sensed (e.g., which region contains the temperature sensor), one of the regions tends to reach an undesirable, inappropriate, or suboptimal temperature. If the heater is controlled by a sensor inside the incubator (such as a patient-end temperature sensor), the region outside the incubator tends to become too low in temperature, which can lead to condensation. Conversely, if the heater is controlled by a sensor outside the incubator, the region inside the incubator may become too high in temperature, which can result in the patient receiving gas that is too hot. Therefore, this disclosure describes systems and methods that enable heat control within a segmented breathing tube. Here, each section has associated sensors that provide feedback to the control module. While several embodiments are described herein with respect to two sections, such systems can also be extended to accommodate applications using further sections, divisions, or regions. For example, in one embodiment having three temperature sections, sections of the breathing tube may be heated based at least in part on three different temperature sensors within the section. Furthermore, embodiments disclosed herein can control the heat supplied to the breathing tube based at least in part on parameters at the patient end, by bypassing or ignoring one or more sensors located at midpoints along the tube. Furthermore, embodiments disclosed herein can control the heat supplied to the breathing tube using parameters provided by sensors, including, but not limited to, temperature sensors, humidity sensors, flow sensors, and oxygen sensors.

[0023] The control module can monitor and control heating temperatures in multiple areas or sections. The control module can be configured to provide heat to a first section of the breathing tube in a first mode and to provide heat to the entire breathing tube in a second mode, using several embodiments of the connector assemblies described herein. Several embodiments described herein can be used without flying leads, exposed connectors, and / or electrical connection wires at the patient end. The term “flying lead” as used herein includes electrical connection wires extending outside the breathing tube, electrical connection wires extending inside through the breathing tube, and electrical connection wires incorporated, molded, or otherwise formed or embedded as part of the breathing tube. The control module can be located inside or outside the humidifier. In some embodiments, the control module is located inside the humidifier and controls heater wires associated with a first section of the inspiratory limb, a second section of the inspiratory limb, and the expiratory limb, and also reads parameters from sensors associated with the first and second sections of the inspiratory limb and / or the expiratory limb. In some embodiments, the control module is configured to independently control the heater wire associated with the inspiratory limb and the heater wire associated with the expiratory limb.

[0024] The control module can also adaptively change the temperature for each section. For example, the control module can monitor temperature sensors associated with one or more sections. Monitoring may be continuous, periodic, interrupt-based, or event-based. For example, temperature sensor monitoring may be based on reading values ​​from analog / digital converters, determining voltage or current, sensing logical conditions, reading thermostat devices, measuring thermistor values, measuring resistance temperature detectors, measuring thermocouple voltages, or other methods for sensing temperature, such as, but not limited to, semiconductor junction sensors, infrared or thermal radiation sensors, thermometers, indicators, etc. In some embodiments, the temperature sensor is a thermistor.

[0025] In some embodiments, the ratio of power delivered to a first segment of the inspiratory limb and a second segment of the inspiratory limb can be changed in use, at least in part, based on feedback from sensors associated with each segment. For example, the power ratio can be changed so that each segment is heated to a temperature that reduces or prevents condensation. As a further example, the power ratio can be changed so that gas that is too hot is not delivered to the patient. In some embodiments, the power ratio can be continuously changed based on feedback from sensors (e.g., temperature sensors, humidity sensors, oxygen sensors, flow sensors, etc.). The power ratio can be changed in a variety of ways. For example, the power ratio can be changed by changing the amplitude of the power signal (including, but not limited to, voltage and / or current), the duration of the power signal, or the duty cycle of the power signal, or by other appropriate modifications to the power signal. In one embodiment, the power ratio is changed by changing the magnitude of the current being delivered. Similarly, in some embodiments, the ratio of power delivered to the inspiratory limb and the expiratory limb can be changed in use, at least in part, based on feedback from sensors associated with each limb.

[0026] Some embodiments provide an inhalation limb comprising a heater wire that is contained within a material that isolates the heater wire from the gas path and insulates it from the external environment, rather than being located within the gas path. In some embodiments, the circuitry used to supply power to the heater wire within the section and to read sensors is located within the inhalation limb so as not to be exposed to the external environment. In some embodiments, the heater wire is molded within an inhalation or exhalation tube so that the end of the heater wire in a complementary section of the tube contacts an intermediate connector, thus electrically coupling the heater wire to the intermediate connector, where the intermediate connector may be configured to provide circuitry for heater wire control and / or sensor readings. In some embodiments, the duty cycle of the power applied to the heater wire can be adjusted, modified, and / or changed to alter the amount of heat supplied to the gas as the gas flows along the relevant section or limb.

[0027] Several embodiments described herein provide a respiratory humidification system configured to deliver a warm, moist gas to a patient or other user. The gas passes through a liquid chamber filled with a liquid (e.g., water) that is heated using a heater plate. The liquid evaporates within 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 associated heater wires. The heater wires can be selectively powered to provide the humidified gas with a predetermined, desired, appropriate, or selected amount of heat. In some embodiments, the respiratory humidification system can be used with an incubator or a radiant heater or a temperature-controlled environment. A temperature-controlled environment may be a substantially enclosed environment in which the temperature within the environment is strictly controlled within a predetermined temperature limit. The temperature-controlled environment referred to defines a sealed enclosure involving strict temperature control. The inspiratory limb can be partitioned such that a first partition is outside the incubator and a second partition is inside the incubator. Furthermore, a first heater wire set can be associated with a first section, and a second heater wire set can be associated with a second section. The humidification system can be configured to supply power to the first heater wire set in a first mode and to supply power to the second heater wire set in a second mode. In some embodiments, the humidification system can be configured to supply power to the first heater wire set in a first mode and to supply power to the second heater wire set in a second mode. In some embodiments, a first section or first set of heater wires is heated, and both the first and second sets of heater wires are heated only when a temperature control environment or a rapid change occurs within the incubator, such as due to ventilation or a fan or a blanket placed to cover a sensor on a tube in the incubator. The intake limbs may include sensors at the end of each section to provide the humidification system with feedback used when selecting power to supply to the sets of heater wires in the section. In some embodiments, the sensor may be located only at the end of the entire tube, or it may be located within a temperature-controlled environment or in an incubator or radiant heater.In some embodiments, the humidification system may include an expiratory limb having an associated heater wire, similarly selectively controlled by the humidification system. In this disclosure, a segmented limb is described with reference to the inspiratory limb. However, the features described can also be applied to the expiratory limb.

[0028] Respiratory humidification system Figure 1 shows an exemplary respiratory humidification system 100 for supplying humidified gas to a user, the respiratory humidification system 100 having a breathing circuit 200, the breathing circuit 200 including a segmented inspiratory limb 202 having sensors 204a, 204b in each section. The segmented inspiratory limb 202 can be used with an incubator 208 as shown, or with another system where different temperatures exist along the various sections of the inspiratory limb 202, such as a radiant heater or a temperature-controlled environment. The segmented inspiratory limb 202 can be used to provide different levels of heat to the various sections 202a, 202b of the inspiratory limb, reducing or preventing condensation and / or controlling the temperature of the gas supplied to the user.

[0029] The illustrated respiratory humidification system 100 includes a pressurized gas source 102. In some implementations, the pressurized gas source 102 includes a fan or blower. In some implementations, the pressurized gas source 102 includes a ventilation device or other positive pressure generating device. In some implementations, the gas source may be a pressurized gas storage container, and the gas can be supplied by an outlet such as a wall gas source in the hospital. The pressurized gas source 102 includes an inlet 104 and an outlet 106.

[0030] The pressurized gas source 102 provides a flow of fluid (e.g., oxygen, anesthetic gas, air, a mixture of air and oxygen, a gas mixture, etc.) to the humidification unit 108. The fluid flow proceeds from the outlet 106 of the pressurized gas source 102 to the inlet 110 of the humidification unit 108. In the illustrated configuration, the humidification unit 108 is separate from the pressurized gas source 102 and is detachably connected to the pressurized gas source 102. In the illustrated configuration, the humidification unit 108 is shown independently of the pressurized gas source 102, and the inlet 110 of the humidification unit 108 is connected to the outlet 106 of the pressurized gas source 102 by a conduit 112. In some implementations, the pressurized gas source 102 and the humidification unit 108 can be integrated into a single housing.

[0031] While other types of humidification units may be used to obtain the specific features, embodiments, and advantages described herein, the illustrated humidification unit 108 is a pass-over humidifier comprising a humidification chamber 114 and an inlet 110 to the humidification chamber 114. In some implementations, the humidification chamber 114 comprises a body 116 to which a base 118 is attached. A compartment can be defined within the humidification chamber 116, and the compartment is adapted to hold a volume of liquid that can be heated by heat transmitted or supplied through the base 118. In some implementations, the base 118 is adapted to contact a heater plate 120. The heater plate 120 can be controlled by a control device 122 or other suitable component, thereby allowing modification and control of the heat transmitted into the liquid.

[0032] The control device 122 of the humidification unit 108 can control the operation of various components of the respiratory humidification system 100. While the illustrated system is shown using a single control device 122, other configurations may use multiple control devices. Multiple control devices may communicate with each other or provide individual functions, thus eliminating the need for communication between them. In some implementations, the control device 122 may comprise a microprocessor, processing unit, or logic circuit with associated memory or storage medium containing software code for a computer program. In such implementations, the control device 122 can control the operation of the respiratory humidification system 100, for example, according to instructions contained in a computer program, and also in response to internal or external inputs. The control device 122, or at least one of multiple control devices, may be located with the breathing circuit, mounted to the breathing circuit, or incorporated as part of the breathing circuit.

[0033] The main body 116 of the humidifying chamber 114 includes a port 124 defining the inlet 110 of the humidifying chamber 114 and a port 126 defining the outlet 128. When the liquid contained inside the humidifying chamber 114 is heated, the liquid vapor is mixed with the gas introduced into the humidifying chamber 114 through the inlet port 124. The mixture of gas and vapor exits the humidifying chamber 114 through the outlet port 126.

[0034] The respiratory humidification system 100 includes a breathing circuit 200 comprising an inspiratory limb 202 connected to an outlet 128 defining an outlet port 126 of a humidification unit 108. The inspiratory limb 202 transports a mixture of gas and water vapor exiting the humidification chamber 114 toward the user. The inspiratory limb 202 may include a heating element 206 positioned along the inspiratory limb 202, which is configured to reduce condensation along the inspiratory limb 202, thereby controlling the temperature of the gas reaching the user, maintaining the humidity of the gas, or any combination thereof. The heating element 206 can raise or maintain the temperature of the gas and water vapor mixture transported by the inspiratory limb 202. In some implementations, the heating element 206 may be a wire defining a resistance heater. By raising or maintaining the temperature of the gas and water vapor mixture exiting the humidification chamber 114, condensation of water vapor from the mixture is reduced.

[0035] The respiratory humidification system 100 can be used with the incubator 208. The incubator 208 can be configured to maintain a desired environment for the user, for example, a selected, predetermined, or desired temperature inside the incubator 208. Thus, the internal ambient temperature inside the incubator 208 may differ from the external temperature. Thus, the incubator 208 generates, defines, creates, or maintains different temperature zones along the inspiratory limb 202, where the internal temperature is typically higher than the external temperature. Having at least two different temperature zones along the inspiratory limb 202 can cause problems during gas delivery to the user, such as condensation along the inspiratory limb 202, delivery of gas at too high a temperature, or both.

[0036] The respiratory humidification system 100 may include an exhaling limb 210 having an associated heating element 212. In some embodiments, the exhaling limb 210 and the inspiratory limb 202 can be connected using a suitable attachment (e.g., a Y-piece). In some embodiments, the respiratory humidification system 100 may also be used with a radiant heater, under a blanket, or in other systems or situations that form two or more temperature zones. The systems and methods described herein may be used with such systems and are not limited to implementations that incorporate an incubator.

[0037] The inspiratory limb 202 can be divided into sections 202a and 202b, where the first section 202a may be a portion of the inspiratory limb 202 located outside the incubator 208, and the second section 202b (e.g., an incubator extension) may be a portion of the inspiratory limb 202 located inside the incubator 208. The first section 202a and the second section 202b may be of different lengths or the same length. In some embodiments, the second section 202b may be shorter than the first section 202a, and in certain implementations, the second section 202b may be about half the length of the first section 202a. The first category 202a may have lengths of, for example, at least about 0.5m and / or about 2m or less, at least about 0.7m and / or about 1.8m or less, at least about 0.9m and / or about 1.5m or less, or at least about 1m and / or 1.2m or less. The second category 202b may have lengths of, for example, at least about 0.2m and / or about 1.5m or less, at least about 0.3m and / or about 1m or less, at least about 0.4m and / or about 0.8m or less, or at least about 0.5m and / or about 0.7m or less.

[0038] The intake sections 202a and 202b can be coupled to each other to form a single gas supply pipeline. In some embodiments, the first section 202a may include one or more first heater wires 206a and one or more first sensors 204a, and may be used without the second section 202b. The control device 122 can be configured to control the first heater wires 206a and read the first sensors 204a even if the second section 202b is not coupled to the first section 202a. Furthermore, when the second section 202b is coupled to the first section 202a, the control device 122 can be configured to control the first and second heater wires 206a, 206b within each section and to read the first and second sensors 204a, 204b. In some embodiments, the control device 122 can be configured to control the respective first and second heater wires 206a, 206b and read the respective first and second sensors 204a, 204b when the second section 202b is installed. Alternatively, it can be configured to control the first heater wire 206a and read the first sensor 204a when the second section 202b is not installed, without requiring any modification of the control device 122 or the humidification unit 108. Therefore, the same control device 122 and / or humidification unit 108 can be used regardless of whether the inspiratory limb 202 includes both the first section 202a and the second section 202b or only the first section 202a. In some embodiments, the control device 122 can further be configured to control the heater wire 212 in the exhalation limb 210 without modifying the control device 122 or the humidification unit 108. Therefore, the respiratory humidification system 100 can operate with or without the second section 202b attached, and / or with or without the expiratory limb 210 attached. It should be understood that in the absence of the second section 202b, the first section 202a of the inspiratory limb 202 can function as an independent inspiratory limb, for example, when a patient interface is attached to the end of the first section to provide gas to the patient.In some configurations, the control device 122 can control both the first and second sections 202a and 202b, or control only the first section 202a or only the second section 202b.

[0039] In one configuration, the control device 122 is configured to control only the first and second sections 202a, 202b, or simply the first section 202a, based solely on readings from the sensor 204b. In this configuration, the intake pipe 202 may include only one sensor 204b located at the end of the second section, without an intermediate sensor 204a.

[0040] In some embodiments, the first section 202a and the second section 202b are permanently joined to each other to form a single gas supply pipeline. As used herein, “permanently joined” means that sections 202a and 202b are joined to each other by means of, for example, adhesive, friction fit, overmolding, mechanical connector, etc., in such a way that it is difficult to separate them. In some embodiments, the first section 202a and the second section 202b are configured to be releasably joined. For example, the first section 202a can be used for gas supply without the second section 202b, or the first section 202a and the second section 202b can be joined to each other to form a single gas supply pipeline. In some embodiments, the first section 202a and the second section 202b can be configured to be joined to each other in a single configuration. For example, the first section 202a may have a predetermined chamber end (e.g., the end closest to the chamber 114 or humidification unit 108 along the direction of the flow of humidified gas to the patient) and a predetermined patient end (e.g., the end closest to the patient along the direction of the flow of humidified gas to the patient), the chamber end being configured to connect to components in the chamber 114 and / or humidification unit 108. The second section 202b may have a predetermined chamber end and a predetermined patient end, where the chamber end is configured to connect only to the patient end of the first section 202a. The chamber end of the first section 202a may be configured not to connect to any end of the second section 202b. Similarly, the patient end of the first section 202a may be configured not to connect to the patient end of the second section 202b. Similarly, the patient end of the second section 202b may be configured not to connect to any end of the first section 202a. Therefore, the first section 202a and the second section 202b can be configured to be connected in only one direction to form a single gas supply pipeline. In some embodiments, the first section 202a and the second section 202b can be configured to be connected in various configurations.For example, the first section 202a and the second section 202b may be configured so as not to include a predetermined patient end and / or a predetermined chamber end. As another example, the first section 202a and the second section 202b may be configured such that the patient end and / or chamber end of the first section 202a can be coupled to the chamber end or patient end of the second section 202b. Similarly, the first section 202a and the second section 202b may be configured such that the chamber end and / or patient end of the second section 202a can be coupled to the patient end or chamber end of the second section 202b.

[0041] The respiratory humidification system 100 includes an intermediate connector 214, which can be configured to electrically couple the elements of the first section 202a and the second section 202b of the inspiratory limb 202. The intermediate connector 214 can be configured to electrically couple the heater wire 206a of the first section 202a to the heater wire 206b of the second section 202b, enabling control of the heater wires 206a, 206b using the control device 122. The intermediate connector 214 can be configured to electrically couple the second sensor 204b of the second section 202b to the first sensor 204a of the first section, allowing the control device 122 to acquire the respective outputs of the sensors. The intermediate connector 214 may include electrical components that enable selective control of the heater wires 206a, 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 and 206b in a second mode. Examples of electrical components included in the intermediate connector 214 include, but are not limited to, resistors, diodes, transistors, relays, rectifiers, switches, capacitors, inductors, integrated circuits, microcontrollers, microprocessors, RFID chips, and wireless communication sensors. In some embodiments, the intermediate connector 214 may be configured inside the intake limb 202 such that it is substantially shielded from external elements (for example, less than 1% of water, particulate matter, contaminants, etc. from the environment outside the intake limb 202 come into contact with the intermediate connector 214). In some embodiments, some of the electrical components in the intermediate connector 214 may be configured to be physically isolated from the humidifying gas inside the intake limb 202 in order to reduce or prevent damage that may occur due to exposure to moisture. In some embodiments, the intermediate connector 214 may include relatively inexpensive passive electrical components to reduce costs and / or increase reliability.

[0042] The inspiratory limb 202 may contain sensors 204a and 204b within their respective sections 202a and 202b. The first sensor 204a can be positioned near the incubator 208 and near the end of the first section 202a, so that the parameters derived from the first sensor 204a correspond to the parameters of the humidifying gas entering the second section 202b. The second sensor 204b can be positioned near the end of the second section 202b, so that the parameters derived from the second sensor 204b correspond to the parameters of the humidifying gas supplied to the patient or user. The outputs of sensors 204a and 204b can be transmitted to the control unit 122 as feedback for use in controlling the power supplied to the heating elements 206a and 206b of the inspiratory limb sections 202a and 202b. In some embodiments, one or both of sensors 204a and 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, but not limited to, a thermistor, a thermocouple, a digital temperature sensor, a transistor, etc. Parameters provided by or derived from the sensors may include, but not limited to, temperature, humidity, oxygen content, flow rate, or any combination thereof.

[0043] The control device 122 can be configured to control the heater wires 206a and 206b, receive feedback from sensors 204a and 204b, provide logic for controlling power to the heater wires 206a and 206b, adjust the control of the heater wires 206a and 206b in accordance with readings from sensors 204a and 204b, detect the presence of a second section 202b of the intake limb 202, derive parameters from readings from sensors 204a and 204b, and so on. In some embodiments, the control device 122 includes a power supply configured to supply power to the heater wires. The power supply may be AC ​​or DC. In some embodiments, the control device 122 can receive input from a heater plate sensor 130. The heater plate sensor 130 can provide the control device 122 with information regarding the temperature and / or power consumption of the heater plate 120. In some embodiments, the control device 122 can receive input from a flow sensor 132. Any suitable flow sensor 132 can be used, and the flow sensor 132 can be positioned between the ambient air and the humidification chamber 114, or between the pressurized gas source 102 and the humidification chamber 114. In the illustrated system, the flow sensor 132 is positioned at the inlet port 124 of the humidification chamber 114.

[0044] Segmented inspiratory limbs Figure 2 shows a portion of a segmented inspiratory limb 202 for use with a respiratory humidification system 100, the segmented inspiratory limb 202 comprising a first segment 202a and a second segment 202b, and having an intermediate connector 214, the intermediate connector 214 is configured to connect a first heater wire 206a located in segments 202a and 202b to a second heater wire 206b, and a first sensor 204a to a second sensor 204b. The coupling of the two segments 202a and 202b may include mechanically coupling the segments to form a single conduit through which humidified gas can be delivered to the user, where the mechanical coupling of segments 202a and 202b allows for the electrical coupling of the respective heater wires 206a and 206b and the respective sensors 204a and 204b by the intermediate connector 214.

[0045] The segmented intake limbs 202 may comprise a structure 216 that forms a lumen through which a humidifying gas can pass. The structure 216 may include a path formed in the wall of the structure 216 configured to house a heater wire 206a or 206b, thereby shielding the heater wire 206a or 206b from the humidifying gas traveling through the lumen and / or covering it from exposure by the outer surface of the structure 216. For example, the structure 216 may be a spiral bubble tube, and the heater wire path may be a coil formed within the tube. The structure 216 may comprise any type of suitable material, and may include insulating and / or flexible materials. In some embodiments, the structure 216 and the intermediate connector 214 may be configured such that the heater wires 206a and 206b wind around the intermediate connector 214 so as to be electrically coupled to the intermediate connector 214 when the first segment 202a and the second segment 202b are mechanically coupled. In some embodiments, the first section 202a and / or the intermediate connector 214 may also be configured to eliminate flying leads for connecting to the second section 202b, thereby facilitating the connection of the second section 202b to the first section 202a.

[0046] The structure 216 at the complementary ends of the first section 202a and the second section 202b can be configured to accommodate an intermediate connector 214. Thus, the intermediate connector 214 may be located inside the inspiratory limb 202. In some embodiments, the complementary ends of the first section 202a and the second section 202b can be configured to shield the intermediate connector 214 from the humidifying gas traveling through the inspiratory limb 202. In some embodiments, the intermediate connector 214 is located inside the inspiratory limb 202 and shielded from the humidifying gas in the conduit, thereby reducing or preventing exposure of electrical connection wires at the intermediate connector 214. In exemplary configurations, the intermediate connector or at least the portion of the intermediate connector 214 located inside the lumen is overmolded with a silicone or plastic material to form a protective layer or coating.

[0047] In some embodiments, the first heater wire 206a may comprise two wires 218 and 220, and the second heater wire 206b may comprise two wires 222 and 224. The two wires 218 and 220 of the first section 202a can be electrically coupled to each other via an electrical component 228, and the electrical coupling creates an electrical path through wire 218, at least a portion of the electrical component 228, and wire 220. Similarly, the two wires 222 and 224 of the second section 202b can be electrically coupled to each other via an electrical component 228 and / or electrically short-circuited to each other at the end of section 202b opposite to the intermediate connector 202b via a patient end connector (not shown), which is described in more detail herein with reference to, for example, Figures 3A, 3B, 8A, 8B, 9, and 13. By connecting wires 222 and 224 of the second section 202b with an intermediate connector 214, the electrical connection wires 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.

[0048] The intermediate connector 214 can be configured so that a single control device can control power to the heater wires 206a and 206b, which may be the humidifier control device 122 described herein with reference to Figure 1. In some embodiments, the humidifier control device 122 controls the heater wires without additional control functions located in the intermediate connector 214. For example, the intermediate connector 214 may include passive components that do not have logic circuits, and these passive components supply power to the heater wires 206a and / or 206b selected by the control device 122. This allows the intermediate connector 214 to be designed using relatively inexpensive components, thereby reducing design complexity.

[0049] In some embodiments, heating of sections 202a and 202b can be achieved using up to four wires within each section 202a, 202b. For example, in the first section 202a, the four wires may include a first heater wire 218, a second heater wire 220, a signal sensor wire 228, and a feedback sensor wire 230. In the second section 202b, the four wires may include a first heater wire 222, a second heater wire 224, a signal sensor wire 232, and a feedback sensor wire 234. By connecting the second heater wires 222, 224 to the first heater wires 218, 220 at connection point 226, and by connecting the second sensor wires 232, 234 to the first sensor wires 228, 230 at connection point 226, the control device can be configured to individually power the first heater wire 206a and the second heater wire 206b and individually read sensor data from sensors 204a and 204b, without including five or more wires in section 202a or 202b. In some embodiments, the control of the heater wires 206a and 206b, and the reading of sensors 204a and 204b can also be achieved using three or fewer wires in each section (e.g., using three wires or two wires), or using five or more wires in each section (e.g., using five wires, six wires, seven wires, eight wires, or nine or more wires).

[0050] The intermediate connector 214 may include an electrical component 228 configured to allow the control device 122 to selectively control the heater wires 206a and 206b. The control device 122 can be configured to control the heating of the inspiratory limb 202 using two modes: a first control mode which includes providing power to the heater wire 206a in a first section, and a second control mode which includes providing power to the heater wires 206a and 206b in the first and second sections 202a and 202b. Thus, the control device 122 can be configured to control the heater wire sections individually. This feature allows the control device 122 to control the heating of the inspiratory limb 202 by controlling only the heating of the inspiratory limb according to the first control mode when the second section 202b is not present, thereby allowing the respiratory humidification system 100 to be used in various situations without modifying the control device 122 or the humidification unit 108. In some embodiments, the control mode may include a mode in which power is supplied only to the heater wire 206b in the second section 202b. In some embodiments, the control device 122 includes a power supply that provides current. The first and second control modes may be based at least in part on the voltage supplied by the power supply, with a positive voltage or positive current triggering the first control mode and a negative voltage or negative current triggering the second control mode. In some embodiments, the power supply provides rectified AC or DC power to the heater wires 206a, 206b, and a change in rectification or polarity triggers a change in the control mode. By switching the control mode, control of heating in the breathing circuit 200 can be achieved using any power supply that can switch the polarity of the output signal. In some embodiments, the amount of power supplied to the heater wires 206a, 206b can be adjusted by adjusting the duty cycle of the power applied to the heater wires 206a, 206b. For example, pulse width modulation (PWM) can be used to power the heater wires 206a and 206b, and the duty cycle of the PWM can be adjusted to control the power being supplied.In another example, the amount of power supplied to the heater wires 206a and 206b can be adjusted by controlling the amplitude of the power signal.

[0051] The intermediate connector 214 may include an electrical component 230 configured to allow the control unit 122 to selectively read sensors 204a and 204b. As described herein with reference to Figures 6A, 6B, and 7, selective reading can be achieved by using a current source, by applying a positive current across wires 228-230 so that the control unit 122 measures a signal from the first sensor 204a, and by applying a negative current across wires 228 and 230 so that the control unit 122 measures a signal from the second sensor 204b, or from both the first sensor 204a and the second sensor 204b. The control unit 122 can use the readings from sensors 204a and 204b to adjust the power to the heater wires 206a and 206b, for example, by using pulse width modulation. The first sensor 204a can be positioned near the connection point or intersection of the first section 202a and the second section 202b, and provides the control unit 122 with parameters of the gas entering the second section 202b (which may correspond to entering an incubator or other such area with a different ambient temperature). The second sensor 204b can be positioned at the patient end of the second section 202b, and provides the control unit 122 with parameters of the gas being supplied to the patient, or the gas parameters in front of the patient's upstream end piece, such as a Y-piece. The control unit 122 can use these readings to adjust the power to the heater wires 206a, 206b to maintain the gas temperature at the patient end of the inspiratory limb 202 at a target temperature or an appropriate temperature. The target temperature or appropriate temperature may vary, at least in part, depending on the application and environment in which it is used, and may be approximately 37°C, approximately 40°C, at least approximately 37°C and / or approximately 38°C or lower, at least approximately 36.5°C and / or approximately 38.5°C or lower, at least approximately 36°C and / or approximately 39°C or lower, at least approximately 35°C and / or approximately 40°C or lower, at least approximately 37°C and / or approximately 41°C or lower, or at least approximately 39.5°C and / or approximately 40.5°C or lower. In some embodiments, the second sensor 204b may be positioned inside the incubator but not attached to the breathing circuit.For example, the temperature of the second section 202b can be calculated by measuring parameters inside the incubator.

[0052] The control device 122 can independently control the amount of power supplied in the first and second control modes, as described herein. Based at least in part on feedback from sensors 204a and / or 204b, the control device 122 can independently adjust the power supplied in the first and second control modes, thereby changing the ratio of heater power between the first section 202a and the second section 202b.

[0053] In some embodiments, the first sensor 204a is positioned within the gas flow inside the inspiratory limb 202. In some embodiments, the intermediate connector 214 or the first section 202a may include mechanical components that reduce turbulence in the gas flow across the first temperature sensor 204a, which can improve the accuracy of the sensor 204a readings. For example, the mechanical connector may have an aerodynamic cross section, some examples of which are described for patient end connectors with reference to Figures 15B-15E. In some embodiments, mechanical components that reduce turbulence (e.g., cross member members inside the inspiratory duct) also fix the sensor 204a in the gas flow. In some embodiments, the intermediate connector 214 and mechanical components are configured to insulate the sensor 204a from electrical components located in the intermediate connector 214, which may be advantageous, for example, if the sensor 204a is a temperature sensor.

[0054] In some embodiments, the intermediate connector 214 includes additional connection points in addition to the connection point 226 shown in Figure 2. These additional connection points can be used to incorporate further functionality into the breathing circuit, such as a memory device (PROM) or (EPROM), a microcontroller, or additional circuitry.

[0055] Intermediate connector circuit Figure 3A shows a schematic diagram of an exemplary intermediate connector 214, which includes an active rectifier power supply for supplying power to heater wires in the segmented inspiratory limb of the breathing circuit, and the circuit is configured to supply power to heater wires R1 and R2 in a first segment of the inspiratory limb in a first mode, and to supply power to heater wires R1, R2, R3, and R4 in both segments in a second mode. Alternatively, power can be applied through heater wires R1 and R2 (where the resistors are the heater wires) or through heater wires R1, R2, R3, and R4 by providing diodes D1 and D2 and switches S1 and S2 in the intermediate connector 214.

[0056] The power supply is indicated in the figure using the symbols VP and VN, where these symbols correspond to the terminals of the power supply. In one embodiment, the voltage source is an alternating current (AC) power supply. Alternatively, the power supply may be a direct current (DC) power supply. Although described as diodes in this embodiment, D1 and D2 may include any of several different types of flow control devices, such as, but are not limited to, rectifiers, transistors, relays, switches, triacs, MOSFETs, thyristors (SCRs), thermostats, etc.

[0057] Switches S1 and S2 switch between the VP and VN terminals of the power supply. In one embodiment, switches S1 and S2 are switched every half cycle of the AC power cycle, thereby drawing approximately equal current from the power supply during each half cycle. Using the circuit shown in Figure 3A, heaters R1, R2, R3, and R4 can be controlled in two control modes: the first control mode corresponds to supplying power to R1 and R2 only, and the second control mode corresponds to supplying power to R1, R2, R3, and R4. To supply power to heaters R1 and R2 in the first section 202a only (which corresponds to the first control mode), during the positive cycle from the power supply, switch S1 is connected to VP and switch S2 is connected to VN, and during the negative cycle from the power supply, switch S1 is connected to VN and switch S2 is connected to VP. In the first control mode, current flows through R1, R2, and D1, and D2 prevents current from flowing through R3 and R4. To supply power to heaters R1, R2, R3, and R4 in the first and second sections 202a and 202b (corresponding to the second control mode), during a positive cycle from the power supply, switch S1 is connected to VN and switch S2 is connected to VP, and during a negative cycle from the power supply, switch S1 is connected to VP and switch S2 is connected to VN. In the second control mode, current flows through R1, R2, R3, R4, and D2, with D1 preventing current from flowing through the wires and short-circuiting without passing through heaters R3 and R4. As described herein with reference to Figure 5, the switching of switches S1 and S2 can be achieved by hardware or software that adds logic to the system. In some embodiments, the switching of S1 and S2 is performed at the zero crossing of the AC power circuit. In some embodiments, the falling and rising edges of the zero crossing circuit are not delayed by the same amount, and the circuit is inactive near the zero crossing. Therefore, the switching of switches S1 and S2 can be performed with or without zero-crossing switching detection and / or logic.

[0058] Diodes D1 and D2 may lose power and therefore generate heat within the circuit. In some embodiments, Schottky diodes can be used when it is desirable to reduce power loss in relatively high-temperature environments. Schottky diodes can be operated near their maximum junction temperature to reduce or minimize power loss, which may be desirable in certain implementations of the respiratory humidification systems described herein. In some embodiments, the heat generated by the diodes may affect the temperature reading of sensor 204a. To reduce this effect, the diodes may be thermally connected to the airflow path of the circuit. To reduce this effect and dissipate the heat generated by the diodes, a heat sink or pad thermally coupled to the ambient environment may be included in the intermediate connector 214. To reduce this effect and the effect of other components on the intermediate connector 214, the sensor 204a (e.g., a thermistor or other temperature sensor) may be insulated from its components and positioned relatively far from the other components, as described with reference to Figures 14A-B and 15.

[0059] Figure 3B shows another schematic of an exemplary intermediate connector 214, which includes an active rectifier power supply for supplying power to heater wires in the segmented inspiratory limb of the breathing circuit, and the circuit is configured to supply power to heater wires R1 and R2 in a first segment of the inspiratory limb in a first mode, and to supply power to heater wires R1, R2, R3, and R4 in both segments in a second mode. As shown in Figure 3B, only diode D1 may be provided, and the power path through heater wires R1 and R2, or through heater wires R1-R4, can still be controlled in the same way as described above with respect to Figure 3A. Diode D2 shown in the circuit of Figure 3A is omitted. The circuit shown in Figure 3B with only one diode D1 reduces the heat generated by the circuit, lowers component costs, and allows for a smaller circuit board. The remainder of the circuit shown in Figure 3B operates in a similar manner to that described in Figure 3A. In the 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 ignored and therefore does not affect the performance of the humidification system.

[0060] In addition to the AC operation described with respect to Figures 3A and 3B, similar circuits can also be operated using a DC power supply. Switches S1 and S2 can be switched based, for example, on time, the output current of the power supply, feedback from a sensor, or at least in part on other control inputs. In such embodiments, the circuits shown in Figure 3A or 3B can be used to control the heaters R1, R2, R3, and R4 in two control modes, where the first control mode corresponds to supplying power to R1 and R2 only, and the second control mode corresponds to supplying power to R1 through R4. To supply power to heaters R1 and R2 only in the first section 202a (which corresponds to the first control mode), switch S1 is connected to VP and switch S2 is connected to VN. In the first control mode, current flows through R1, R2, and D1. D2 prevents current from flowing through R3 and R4 in the circuit shown in Figure 3A. However, as shown in Figure 3B, D2 is an optional component. To supply power to heaters R1, R2, R3, and R4 in the first and second sections 202a and 202b (corresponding to the second control mode), switch S1 is connected to VN and switch S2 is connected to VP. In the second control mode, current flows through R1, R2, R3, and R4, and D1 prevents current from flowing through the wires and short-circuiting without passing through heaters R3 and R4. As previously mentioned, switching can be achieved by adding logic to the system with hardware or software, as described herein with reference to Figure 5.

[0061] Control of inspiratory and expiratory limb heaters Furthermore, Figure 1 shows an exemplary respiratory humidification system 100 having an inspiratory limb 202 and an expiratory limb 210, the humidification system 100 is configured to control heater wires 206, 212 in both limbs. In some embodiments, the expiratory heater wire 212 in the expiratory limb 210 can be electrically coupled to the inspiratory heater wire 206 outside the humidification unit 108 and control device 122, thereby allowing control of the expiratory heater wire 212 to be performed without affecting other control modes and without the use of additional switching transistors. Similarly, the expiratory heater wire 212 can also be electrically coupled to the inspiratory heater wire 206 inside the humidification unit 108. The connection of the expiratory heater wire 212 to the inspiratory heater wire 206 can be done within the humidification system 108, on an intermediate connector 214, or within a sensor cartridge in the humidification system 108, etc. Therefore, the control device 122 can control the exhalation heater wire 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 coupling between the exhalation heater wire 212 and the inhalation heater wire 206 inside the humidification unit 108 are shown in Figures 4A-4D, 8A, and 8B.

[0062] Referring to Figure 4A, the humidification unit 108 can incorporate switches or relays S3 and S4 to allow selection between independent and dependent control of the inhalation heater wires and the exhalation heater wires. In some embodiments, the switches or relays are activated when a tube with appropriate identification (e.g., inhalation or exhalation 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 and S4 are open), the heater wires in the inhalation limb and / or the heater wires in the exhalation limb can be controlled individually and / or independently.

[0063] When the appropriate tubes are connected, or when the system determines that the tubes are appropriate, switches S3 and S4 can be closed to control the inspiratory and expiratory limbs simultaneously. The humidification unit 108 may include an inspiratory power supply INSP and an expiratory power supply EXP, where the system may perform switching of each power supply as described herein with reference to Figures 3A and 3B. For example, with reference to Figure 3A, the inspiratory power supply may have switches S1 and S2 configured to selectively supply positive and negative cycles to heaters R1-R4. Similarly, with reference to Figure 4A, the expiratory power supply EXP may include switches configured to selectively supply power to expiratory limbs 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, thereby supplying power to the inspiratory heater wires and 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 embodiments, the intake power supply INSP is used to provide power to the intake heater wire when switches S3 and S4 are open, and to provide power to both the intake heater wire and the exhalation heater wire when switches S3 and S4 are closed. Thus, the intake limb heater wire 206 can be controlled in the same manner as described above, but here the system can simultaneously control the power to the exhalation heater wire 212 and the intake heater wire 206 using switches S3 and S4 and a unified electrical circuit and / or control system. For example, the humidifying unit 108 operates in two modes with respect to the inspiratory limb 202 (for example, a first mode in which the humidifying unit 108 provides power to heaters R1 and R2, and a second mode in which it provides power to heaters R1 to R4), and at the same time, it can selectively control the power to heaters R5 and R6 in the expiratory limb. Thus, the humidifying unit 108 can provide power to heaters R5 and R6, or not provide power to heaters R5 and R6, while operating in the first mode, the second mode, or both modes. As mentioned above, the connection between the inspiratory limb 202 and the expiratory limb 210 can be made inside or outside the humidifying unit 108.In one embodiment, the connection is made inside the sensor cartridge, at the intermediate connector 214, or at another location.

[0064] In some embodiments, an exhalation circuit configured to connect the exhalation heater wire 212 to the control unit 122 can be implemented in the intermediate connector 214 shown in Figure 1. The exhalation circuit can be connected in one or more ways. For example, the exhalation circuit can be connected parallel to the heater wire 206a in the first section 202a, or parallel to the heater wire 206b in the second section 202b. In some embodiments, the intermediate connector 214 may include an internal fly or flying lead to make the exhalation circuit available at the intermediate connector 214. In some embodiments, the intermediate connector 214 can be connected to an additional third channel, thereby eliminating the flying lead between the inspiratory and exhalation circuits. To address such embodiments, a heater wire driver control circuit can be added to the control unit 122.

[0065] Figure 4B shows an exemplary embodiment of a humidification system in which a power supply 405 is incorporated by a combination of switches or relays S1-S6 and diode D1 to provide power to both inhalation heater wires R1-R4 and exhalation heater wires R5 and R6. In the exemplary embodiment, the humidification system is configured to provide power to the exhalation heater wires when only the inhalation heater wires R1, R2 in a first section of the inhalation limb are receiving power (e.g., in a first operating mode), or when both inhalation heater wires R1-R4 in both sections are receiving power (e.g., in a second operating mode). The power supply 405 may be any suitable power supply, including a power supply that provides alternating current in, for example, a sine wave, sawtooth wave, square wave, or other form. In some embodiments, the power supply 405 may be a transformer that provides an alternating current signal at a voltage of at least about 22VAC, at least about 5VAC or about 30VAC or less, at least about 10VAC or about 25VAC or less, or at least about 12VAC or about 22VAC or less.

[0066] Continuing to refer to Figure 4B, the humidification system can be configured to power the exhalation heater wires R5 and R6 in a first operating mode while the power supply 405 is providing power in a negative cycle. To do this, switches S1, S2, S5, and S6 are closed and switches S3 and S4 are opened. Current flows from the negative terminal of the power supply 405 through switch S2 and branches to power both the inspiratory and exhalation heater wires. In the inspiratory limb, the current flows to the inspiratory heater wire R2, then through D1 to the inspiratory heater wire R1, and then back to the positive terminal of the power supply 405 through switch S1. In the exhalation limb, the current flows through switch S6 to the exhalation heater wire R5, then to the exhalation heater wire R6, and then back to the positive terminal of the power supply 405 through switches S5 and S1.

[0067] Similarly, continuing to refer to Figure 4B, the humidification system can be configured to power the exhalation heater wires R5, R6 in a first operating mode while the power supply 405 is supplying power in a positive cycle. To do this, switches S3, S4, S5, and S6 are closed and switches S1 and S2 are opened. Current flows from the positive terminal of the power supply 405 through switch S3 and branches to supply power to both the inspiratory and exhalation heater wires. In the inspiratory limb, the current flows through switch S6 to the inspiratory heater wire R2, then through diode D1 to the inspiratory heater wire R1, and then back to the negative terminal of the power supply 405 through switches S5 and S4. In the exhalation limb, the current flows through the exhalation heater wire R5, then through the exhalation heater wire R6, and then back to the negative terminal of the power supply 405 through switch S4.

[0068] Continuing to refer to Figure 4B, the humidification system can be configured to power the exhalation heater wires R5 and R6 in a second operating mode while the power supply 405 is supplying power in the positive cycle. To do this, switches S1, S2, S5, and S6 are closed and switches S3 and S4 are opened. Current flows from the positive terminal of the power supply 405 through switch S1 and branches to supply power to both the inspiratory and exhalation heater wires. 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, and then back to the negative terminal of the power supply 405 through switch S2. In the exhalation limb, the current flows to the exhalation heater wire R6 through switch S5, then to the exhalation heater wire R5, and then back to the negative terminal of the power supply 405 through switches S6 and S2.

[0069] Similarly, referring to Figure 4B, the humidification system can be configured to power the exhalation heater wires R5 and R6 in a second operating mode while the power supply 405 provides power in the negative cycle. To do this, switches S3, S4, S5, and S6 are closed and switches S1 and S2 are opened. Current flows from the negative terminal of power supply 405 through switch S4 and branches to power the heater wires of both the inspiratory and exhalation limbs. In the inspiratory limb, the current flows through switch S5 to the inspiratory heater wire R1, then through the inspiratory heater wire R3 without passing through diode D1, then through the inspiratory heater wire R4, then through the inspiratory heater wire R2, and then back to the positive terminal of power supply 405 through switches S6 and S3. In the exhalation limb, the current flows through the exhalation heater wire R6, then through the exhalation heater wire R5, and then back to the positive terminal of power supply 405 through switch S3.

[0070] Figure 4C shows an exemplary embodiment of a humidification system in which a power supply 405 is incorporated by a combination of switches or relays S1-S6 and diodes D1, D2 to provide power to both inhalation heater wires R1-R4 and exhalation heater wires R5 and R6. In the exemplary embodiment, the humidification system is configured to provide power to the exhalation heater wires when only the inhalation heater wires R1, R2 in a first section of the inhalation limb are receiving power (for example, in a first operating mode).

[0071] Continuing to refer to Figure 4C, the humidification system can be configured to power the exhalation heater wires R5 and R6 in a first operating mode while the power supply 405 is providing power in a negative cycle. To do this, switches S1, S2, S5, and S6 are closed and switches S3 and S4 are opened. Current flows from the negative terminal of the power supply 405 through switch S2 and branches to power both the inspiratory and exhalation heater wires. In the inspiratory limb, the current flows to the inspiratory heater wire R2, then through D1 to the inspiratory heater wire R1, and then back to the positive terminal of the power supply 405 through switch S1. In the exhalation limb, the current flows through switch S6 and diode D2 to the exhalation heater wire R5, then to the exhalation heater wire R6, and then back to the positive terminal of the power supply 405 through switches S5 and S1.

[0072] Similarly, continuing to refer to Figure 4C, the humidification system can be configured to power the exhalation heater wires R5, R6 in a first operating mode while the power supply 405 provides power in a positive cycle. To do this, switches S3, S4, S5, and S6 are closed and switches S1 and S2 are opened. Current flows from the positive terminal of the power supply 405 through switch S3 and branches to power the heater wires of both the inspiratory and exhalation limbs. In the inspiratory limb, the current flows through switch S6 to the inspiratory heater wire R2, then through diode D1 to the inspiratory heater wire R1, and then back to the negative terminal of the power supply 405 through switches S5 and S4. In the exhalation limb, the current flows through diode D2 to the exhalation heater wire R5, then to the exhalation heater wire R6, and then back to the negative terminal of the power supply 405 through switch S4.

[0073] Continuing to refer to Figure 4C, the humidification system can be configured to supply power only to the inhalation heater wires R1-R4 (without supplying power to the exhalation heater wires R5 and R6) in a second operating mode, while the power supply 405 is supplying power in the positive cycle. To do this, switches S1, S2, S5, and S6 are closed and switches S3 and S4 are opened. Current flows from the positive terminal of the power supply 405 through switch S1 to the inhalation heater wire R1, then through the inhalation heater wires R3, R4, and 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, together with the switches configured as described above, blocks the flow of current through its circuit in the positive cycle.

[0074] Continuing to refer to Figure 4C, the humidification system can be configured to supply power only to the inhalation heater wires R1-R4 (but not to the exhalation heater wires R5 and R6) in a second operating mode while the power supply 405 is supplying power in the negative cycle. To do this, switches S3, S4, S5, and S6 are closed and switches S1 and 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 through the inhalation heater wires R3, R4, and 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 the switches configured as described above, blocks the flow of current through its circuit in the negative cycle.

[0075] Figure 4D shows an exemplary embodiment of a humidification system incorporating a power supply 405, which, by combination of switches or relays S1-S6 and diode D1, provides power to both the inspiratory heater wires R1-R4 and the expiratory heater wires R5 and R6, and the expiratory heater wires R5 and R6 are 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 can result in an intermediate connector, such as any intermediate connector described herein. As described with reference to Figure 4D, the expiratory heater wires R5 and R6 are coupled to the inspiratory heater wires R1-R4 with an intermediate connector, but any suitable position after the inspiratory heater wires in the first section can be used to couple the heater wires of the inspiratory and expiratory limbs. In the 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 operating mode).

[0076] Continuing to refer to Figure 4D, the humidification system can be configured to supply power to the inhalation heater wires R1-R4 and exhalation heater wires R5, R6 in a second operating mode while the power supply 405 is supplying power in the positive cycle. To do this, switches S1, S2, S5, and S6 are closed and switches S3 and S4 are opened. Current flows from the positive terminal of the power supply 405 through switch S1 to the inhalation heater wire R1, and then branches off to supply power to the heater wires of both the second section of the inhalation limb and the exhalation limb, without passing through diode D1. In the second section of the inhalation limb, current flows to the inhalation heater wire R3, then to the inhalation heater wire R4, and returns to the intermediate connector. In the exhalation limb, current flows to R5, then to R6, and returns to the intermediate connector. Current then flows through the inhalation heater wire R2, and then through switch S2 to the negative terminal of the power supply 405.

[0077] Similarly, continuing to refer to Figure 4D, the humidification system can be configured to power the exhalation heater wires R5 and R6 in a second operating mode while the power supply 405 provides power in a negative cycle. To do this, switches S3, S4, S5, and S6 are closed and switches S1 and S2 are opened. Current flows from the negative terminal of the power supply 405 through switches S4 and S5 to the inhalation heater wire R1, and then branches off to power the heater wires of both the second section of the inspiratory limb and the exhalation limb, bypassing the diode D1. In the second section of the inspiratory limb, the current flows to the inhalation heater wire R3, then to the inhalation heater wire R4, and back to the intermediate connector. In the exhalation limb, the current flows to R5, then to R6, and back to the intermediate connector. The current then flows through the inhalation heater wire R2, and then back to the positive terminal of the power supply 405 through switches S6 and S3.

[0078] Continuing to refer to Figure 4D, the humidification system can be configured to supply power only to the inhalation heater wires R1 and R2 in the first section of the inhalation limb (without supplying power to the exhalation heater wires R5 and R6) in the first operating mode while the power supply 405 is supplying power in the negative cycle. To do this, switches S1, S2, S5, and S6 are closed and switches S3 and S4 are opened. Current flows from the negative terminal of the power supply 405 through switch S2 to the inhalation heater wire R2, then through diode D1 to the inhalation heater wire R1, and then back to the positive terminal of the power supply 405 through switch S1.

[0079] Similarly, continuing to refer to Figure 4D, the humidification system can be configured to supply power only to the inhalation heater wires R1 and R2 in the first section of the inhalation limb (without supplying power to the exhalation heater wires R5 and R6) in the first operating mode while the power supply 405 is supplying power in the positive cycle. To do this, switches S3, S4, S5, and S6 are closed and switches S1 and S2 are opened. Current flows from the positive terminal of the power supply 405 through switches S3 and S6 to the inhalation heater wire R2, then through diode D1 to the inhalation heater wire R1, and back to the negative terminal of the power supply 405 through switches S5 and S4.

[0080] Other circuit designs and configurations are also possible for controlling intake heaters, segmented intake heaters, and / or exhalation heaters. Power control to the various heaters can be controlled by a control device or control module, such as the control device 122 described with reference to Figure 1. The control module may be configured to adjust the opening and closing of switches to selectively control power to one or more heaters. For example, a switch can be opened and closed to control the amount of power supplied to the heaters. In certain embodiments, the power supply provides alternating current, and the switch can be controlled to modulate the amount of power supplied to one or more heaters, for example, using pulse width modulation techniques. As another example, the control module can adjust the operation of a switch to control which heater or heater segment is supplied with power. In some embodiments, each heated segment or heater wire may have its own power supply. This may make it possible to omit diodes configured to regulate the current in the heater wire circuit. In some embodiments, the control algorithm can use flow information to directly control the fixed duty cycle of a first heater segment. In some embodiments, the control algorithm may use ambient temperature readings or measurements to directly control the fixed duty cycle of the first heater section to an adjustment value.

[0081] In some embodiments, a temperature measurement at an intermediate point, i.e., between the patient end and the chamber end, may be used by a control module. For example, a control module may utilize such an intermediate temperature measurement to apply a duty cycle of a first heater section for the purpose of maintaining a target intermediate point temperature. The duty cycle of the first heater section can be adapted to maintain a target temperature difference with respect to the chamber output dew point (humidity) related to the chamber output temperature. The duty cycle of the first heater section can be adapted to continuously maintain a target temperature difference with respect to the patient end measurement temperature. If the duty cycle remains at 100% over the adjusted period and the flow is determined to be non-zero, while the patient end temperature is below the target setpoint by the adjusted value, the chamber output temperature may be advantageously reduced to a calculated target level based at least in part on the combined duty cycles of the first and second heater sections (determined by the patient end temperature).

[0082] In some embodiments, at least a single measurement point within the system can be implemented for temperature feedback control, and the measurement point can be positioned at the system outlet. Such a configuration may be sufficient to achieve the target gas conditions. In certain embodiments, a dual-zone system may not have a temperature sensor if prior knowledge of the heat transfer characteristics of each zone is established for known environmental operating conditions. In such a system, individual power levels may be established zone by zone so that the target gas output conditions can be obtained from accurate measurements of the mass flow rate through the system and knowledge of the gas conditions entering the gas supply system.

[0083] Figure 21A shows an exemplary circuit diagram 2000a configured to independently control two heaters H1 and H2 (e.g., an intake heater, an exhalation heater, a segmented heater, etc.). As used herein, independent control means that the power supply to one of the two heaters does not determine whether power is supplied to the other heater. For example, switches S1 and S3 can be closed and switches S2 and S4 can be opened to supply power to heater H1 only, switches S1 and S3 can be opened and switches S2 and S4 can be closed to supply power to heater H2 only, or switches S1 to S4 can be closed to supply power to both heaters H1 and H2.

[0084] Circuit 2000a may include a power supply 2002 configured to provide power. Power supply 2002 may be an AC or DC power supply. Power supply 2002 may be a voltage source or a current source. Circuit 2000a may include a main relay 2004 configured to control the supply of power to the components of circuit 2000a. The main relay 2004 may open (e.g., to a state that prevents current from flowing) when the system detects a fault condition or when the system decides to cut off power to the heater and / or other electrical components of the breathing circuit.

[0085] In some embodiments, the system can be configured to detect when a possible short circuit occurs between a low-power circuit and a high-power circuit (e.g., a short circuit between a heater and a sensor wire). Short circuits can occur when the high-power circuit and the low-power circuit receive power from a common power source and / or from a common circuit. In certain embodiments, the high-power circuit and the low-power circuit receive power from a transformer that rectifies the power (e.g., from an AC power source), reducing (or increasing) the output voltage to the high-power circuit (e.g., using a voltage divider) and reducing the output voltage to the low-power circuit (e.g., using a voltage divider). For example, the high-power circuit may be configured to provide about 22V and the low-power circuit may be configured to provide about 3.3V. Other voltages are also possible. For example, the high-power circuit may provide voltages of at least about 50V, at least about 30V and / or less than about 50V, at least about 20V and / or less than about 30V, or at least about 10V and / or less than about 25V. As another example, a low-power circuit may provide a voltage of at least about 5V, at least about 3V and / or less than about 5V, at least about 2V and / or less than about 3.5V, or at least about 1.5V and / or less than about 2V. The actual voltage of a low-power circuit may depend on the temperature measured by one or more temperature sensors coupled to the low-power circuit. For example, in a low-power circuit providing about 3.3V, a thermistor measuring a temperature of about 50°C may output a voltage of about 0V, and a thermistor measuring a temperature of about 20°C may output a voltage of about 1.2V.

[0086] The system may include a first comparator referenced to the output of a series of voltage dividers electrically coupled to the output of a transformer configured to supply voltage to a low-power circuit. The first comparator may provide an out-of-range signal when the voltage exceeds a predicted voltage (e.g., a voltage configured to be detected by the comparator). For example, if the predicted range is 0 to 1.2V or 1.5V, the comparator may be configured to provide a signal indicating a possible short circuit when the voltage exceeds 1.2V or 1.5V. The system may include a second comparator referenced to ground, configured to provide a signal indicating a possible short circuit when the voltage is negative. The system may be configured to provide a signal indicating a potential short circuit immediately (e.g., in real time or near real time) when it detects a voltage outside the predicted range. In some embodiments, the system may include logic configured to ignore the short-circuit signal, trigger a warning, and / or turn off or reduce power to the high-power circuit and / or low-power circuit. When the system receives an out-of-range signal, the system may open the main relay 2004 to cut off power to electrical components (e.g., heater wires, sensors, etc.). A short circuit can occur if there is voltage leakage from a high-power circuit to a low-power circuit, which can increase the voltage in the low-power circuit outside the predicted range. Similarly, if a negative bias voltage supplied to a high-power circuit leaks into a low-power circuit, the voltage in the low-power circuit may become negative.

[0087] Circuit 2000a may include switches S1-S4 for controlling power to heaters H1 and H2. As used herein, the term “switch” may be used to refer to an electrical switch and / or any other combination of electrical and / or electromechanical components configured to control the flow of current. For example, a switch may include a MOSFET, diode, transistor, or a combination thereof. Heaters H1 and H2 may be any of the heaters described herein.

[0088] Circuit 2000a may include a control module 2006 configured to control switches S1-S4. The control module 2006 may be configured to provide signals to the switches to indicate a desired state of the receiving switches. For example, the control module may send a signal (e.g., a voltage above a threshold voltage) to switches S1 and S3 or switches S2 and S4 to control them to close. The control module 2006 may be configured to control switches S1 and S3 using one signal and switches S2 and S4 using another signal. In this way, the switch pairs (e.g., switches S1, S3 and / or switches S2, S4) can synchronize their operation (e.g., open and close simultaneously or nearly simultaneously). Circuit 2000a is configured to independently control the heaters H1, H2 by independently controlling the opening and closing of switch pairs S1, S3 and switch pairs S2, S4.

[0089] Figure 21B shows an exemplary circuit diagram 2000b configured to perform gate control of heaters H1 and H2. Circuit 2000b is similar to circuit 2000a except that the flow of power to lines controlled by switches S2 and S4 is controlled by switches S1 and S3, respectively. In this way, the control module 2006 can perform gate control of heaters H1 and H2. As used herein, gate control can mean that the flow of power to heater H1 is controlled by switches S1 and S3, while the flow of power to heater H2 is controlled to a first level by switches S1 and S3 and to a second level by switches S2 and S4. For example, power may flow to heater H2 when switches S1 and S3 are closed, depending on the state of switches S2 and S4. However, when switches S1 and S3 are open, no power flows to heater H2, so the state of switches S2 and S4 is irrelevant. In this way, the hardware can control the operation of heaters H1 and H2. This results in gate control of heater H2, as the control module 2006 can control the power to heater H2 using switches S1 and S3 (for example, by providing a power gate to heater H2). This can be beneficial when hardware control of heaters H1 and H2 is desired to provide additional control mechanisms in addition to software control of the heaters. For example, control software in a humidifier may require that the power to heater H2 be turned on, but this requirement can be disabled by the hardware configuration.

[0090] Figure 21C shows an exemplary circuit diagram 2000c configured to switch between independent control and gate control of heaters H1 and H2. Control module 2006 can control switches S5 and S6 to selectively configure circuit 2000c to an independent control configuration similar to circuit 2000a described herein with reference to Figure 21A, or to a gate control configuration similar to circuit 2000b described herein with reference to Figure 21B. Circuit 200c offers the advantages of both circuits 2000a and 2000b for control module 2006 to select a desired, appropriate, and / or preferred configuration.

[0091] Figure 22A shows an exemplary circuit diagram 2100a including a logic module 2008 and a mode relay 2010 configured to enable control of two heaters (e.g., an intake heater and an exhalation heater) or a segmented heater (e.g., a heater in a segmented intake line). Circuit diagram 2100a includes a power supply 2002, a main relay 2004, and a control module 2006, similar to circuit diagrams 2000a, 2000b, and 2000c described herein with reference to Figures 21A to 21C. Switches S1 to S4 are configured similarly to those in circuit diagram 2000a. However, the logic module 2008 interfaces with the control module 2006 for controlling switches S1 to S4. Furthermore, the mode relay 2010 provides dynamic configuration for different heater configurations.

[0092] The logic module 2008 receives control signals SW1 and SW2 from the control module 2006 and processes these control signals SW1 and SW2 based at least in part on the mode signal MODE from the control module 2006. The mode signal MODE can indicate the intended, selected, or desired mode for circuit 2100a. For example, the mode signal MODE can be used to indicate to the logic module 2008 whether the operation of circuit 2100a is for independent control of the heater or for a segmented heater. Based on the control signals SW1 and SW2 and the mode signal MODE, the logic module 2008 outputs switch signals HW1 and HW2 to control pairs of switches S1, S3 and S2, S4, respectively.

[0093] In certain implementations, the mode signal MODE can be used to indicate a heater independent control mode to logic module 2008. In this case, logic module 2008 can be configured to pass control signals SW1, SW2 to output switch signals HW1, HW2 with little or no modification. In this way, control module 2006 can control the two heaters independently. In some embodiments, mode relay 2010 receives instructions for an operating mode similar to the instruction provided by the mode signal MODE. In response to the received instructions, mode relay 2010 can provide electrical connections to lines 1-4 (corresponding to lines controlled by switches S1-S4). For example, as shown in Figure 22B, mode relay 2010 can provide electrical pass-through to lines 1-4 to enable independent control of heaters H1, H2, similar to the operation of circuit 2000a described herein with reference to Figure 21A.

[0094] In certain implementations, the mode signal MODE can be used to indicate a segmented heater control mode to the logic module 2008. In this case, the logic module 2008 can be configured to selectively control control switches S1-S4 by outputting switch control signals HW1, HW2 to provide rectified electrical signals to the segmented heater. In this way, the control module 2006 can control the segmented heater as described elsewhere in this specification. In some embodiments, the mode relay 2010 receives an instruction for an operating mode similar to the instruction provided by the mode signal MODE. In response to the received instruction, the mode relay 2010 can provide electrical connections to lines 1-4 (corresponding to lines controlled by switches S1-S4). For example, as shown in Figure 22C, the mode relay 2010 can electrically couple lines 1 and 4 and lines 2 and 3 to enable control of a segmented heater with heater segments H1 and H2, similar to the operation of other circuits configured to control segmented heaters as described herein. In this mode, the mode relay 2010 provides the ability to turn on either heater section H1 or both heater sections H1 and H2, at least in part, based on the configuration of switches S1 to S4 and the voltage / current polarity.

[0095] For example, in a segmented heater mode, control module 2006 can use control signal SW1 to indicate a request or demand to provide power to both heater segments H1 and H2. In response to control signal SW1, logic module 2008 can provide switch control signal HW1 to control switches S1 and S3 to close when a positive polarity signal is received from power supply 2002, and switch control signal HW2 to control switches S2 and S4 to close when a negative polarity signal is received from power supply 2002. Similarly, control module 2006 can use control signal SW2 to indicate a request or demand to provide power to heater segment H1 only. In response to control signal SW2, logic module 2008 can provide switch control signal HW2 to control switches S2 and S4 to close when a positive polarity signal is received from power supply 2002, and switch control signal HW1 to control switches S1 and S3 to close when a negative polarity signal is received from power supply 2002. In this way, logic module 2008 enables voltage / current rectification to the segmented heaters H1 and H2.

[0096] The logic module 2008 enables safety latches that may be implemented when operating with a segmented heater control. The logic module 2008 can be configured to set both switch control signals HW1, HW2 to control the opening of switches S1-S4 when both control signals SW1, SW2 indicate a request to operate in their requested modes. The logic module can be used to reduce or prevent malfunctions associated with supplying power to a segmented heater. For example, the power supply 2002 can be used to supply alternating voltages, i.e., alternating positive and negative bias voltages. These currents and / or bias voltages can be controlled by switches S1-S4. By closing all switches S1-S4, both bidirectional currents or both positive and negative bias voltages are supplied to the heater circuit 2100a simultaneously, which may damage the system. The logic module 2008 may include a latch that opens the main relay 2004 when the control module 2006 activates incompatible heater drive units (for example, due to a software or hardware malfunction) (for example, when both pairs of switches S1, S3 and S2, S4 are activated or closed).

[0097] Figure 23 shows exemplary circuit diagram 2100b configured to switch between independent control of two heaters (e.g., circuit diagram 2000a described herein with reference to Figure 21A) and gate control (e.g., circuit diagram 2000b described herein with reference to Figure 21B), and to provide the functionality described with respect to exemplary circuit diagram 2100a shown in Figure 22A. Circuit diagram 2100b provides the switching functionality of circuit diagram 2000c described herein with reference to Figure 21C, along with the functionality provided by circuit diagram 2100a described herein with reference to Figure 22A. To enable this functionality, control module 2006 can provide an additional control signal SW3 that logic module 2008 can use to operate switches S5 and S6 by providing a switch control signal HW3. Switches S5 and S6 can be configured such that switches S1 and S2 are in parallel and switches S3 and S4 are in parallel when operating in heater independent control mode and when operating in segmented heater control mode. Switches S5 and S6 can be configured such that switches S1 and S2 are in series and switches S3 and S4 are in series when operating in heater gate control mode. The logic module 2008 can perform additional checks to ensure that the control signal SW3 is appropriate, based at least in part on the mode signal MODE, which can be configured to provide an indication of selection, request, or preference for operating in heater independent control mode, heater gate control mode, or segmented heater control mode.

[0098] Figure 24A shows an exemplary circuit diagram 2200 configured to control two heaters H1 and H2 in parallel. Circuit 2200 can be configured to be coupled to a heater module 2012a, which contains heaters H1 and H2. Circuit 2200 can be configured to provide an electrical connection to the heater module 2012a, which is similar to that provided by a mode relay 2010 when configured as described herein with reference to Figure 22C. Otherwise, circuit 2200 can be configured to be circuit 2100a, as described herein with reference to Figure 22A.

[0099] Referring to Figure 24A, the circuit 2200 can be configured to supply power in parallel to heaters H1 and H2 in the heater module 2012a. In some embodiments, the heater module 2012a may include one or more diodes to guide the flow of current to one or more of the heaters in the heater module 2012a or to limit the flow of current to one or more of the heaters. For example, Figure 24B shows an exemplary configuration of the heater module 2012a in which both heaters H1 and H2 include diodes to control the flow of current. Diodes D1 and D2 can be used to control when power flows through the associated heaters H1 and H2 in order to provide additional control capability.

[0100] Figure 24B also shows a simplified schematic illustrating the functionality of circuit 2200, which includes a heater module 2012a configured to include diodes D1 and D2. When switches S1 and S3 are closed (and switches S2 and S4 are open), the positive current supplied by power supply 2002 flows through heater H1 but not through heater H2, and the negative current supplied by power supply 2002 flows through heater H2 but not through heater H1. Similarly, when switches S2 and S4 are closed (and switches S1 and S3 are open), the positive current supplied by power supply 2002 flows through heater H2 but not through heater H1, and the negative current supplied by power supply 2002 flows through heater H1 but not through heater H2. In this way, the control module can adjust the opening and closing of switch pairs S1, S3 and S2, S4 by the polarity of the voltage or current supplied by power supply 2002 to selectively energize heaters H1 and H2. In some implementations, diodes D1 and D2 can be configured to have different biases so that current flows through heaters H1 and H2 in the opposite direction to those described above. In certain implementations, either diode D1 or D2 can be removed so that the current is limited in one heater H1 or H2 but not in the other.

[0101] Figure 24C shows an exemplary circuit diagram 2200 configured to control a segmented heater using a heater module 2012b. In this configuration, circuit 2200 with heater module 2012b operates in the same manner as circuit 2100a, as described herein with reference to Figure 22C, when the mode relay 2010 in circuit 2100a is configured to electrically couple lines 1 and 4 and lines 2 and 3 to enable control of a segmented heater comprising heater segments H1 and H2. Figure 24D shows an exemplary configuration of heater module 2012b and a simplified circuit diagram of circuit 2200 to demonstrate the functionality of the circuit when the switches are in various configurations. As described elsewhere herein, both heater segments H1 and H2 can be powered when a positive current is supplied by power supply 2002 and switches S1 and S3 are closed, or when a negative current is supplied by power supply 2002 and switches S2 and S4 are closed. Heater section H1 can be supplied with power when a negative current is provided by power supply 2002 and switches S1 and S3 are closed, or when a positive current is provided by power supply 2002 and switches S2 and S4 are closed.

[0102] Circuit diagram 2200 advantageously allows for connectivity with different heater modules, enabling a single circuit design to operate different heater configurations. This also simplifies control system design, software design, and enhances the interoperability of components for different respiratory devices.

[0103] Figures 25A–25C show an exemplary circuit diagram 2500 for controlling a segmented heater by using an active rectifier circuit that uses back-to-back MOSFETs to quickly and precisely control the direction of current from the A / C power supply 2502. To facilitate the explanation of how exemplary circuit 2500 controls the segmented heater, Figures 25B and 25C show switches S1–S4 as diodes to facilitate understanding of the resulting current flow in the circuit with respect to specific control modes and specific configurations of switching switches, as described below. However, it should be understood that switches S1–S4 are electrical switches, such as MOSFETs, as shown in Figure 25A.

[0104] The active rectifier circuit 2500 can work to supply current to target heater sections H1 and / or H2 by selectively switching MOSFETs S1, S2, S3, and S4. For example, Figure 25B shows a circuit configuration for supplying power to heater sections H1 and H2. When a positive current is supplied by power supply 2502, MOSFETs S1 and S3 can be closed (e.g., switched on) and MOSFETs S2 and S4 can be opened (e.g., switched off), and when a negative current is supplied by power supply 2502, MOSFETs S1 and S3 can be opened (e.g., switched off) and MOSFETs S2 and S4 can be closed (e.g., switched on). Figure 25C shows a circuit configuration for supplying power to heater section H1. When a positive current is supplied by power supply 2502, MOSFETs S1 and S3 can be opened (e.g., switched off) and MOSFETs S2 and S4 can be closed (e.g., switched on), and when a negative current is supplied by power supply 2502, MOSFETs S1 and S3 can be closed (e.g., switched on) and MOSFETs S2 and S4 can be opened (e.g., switched off).

[0105] In some embodiments, the exhalation heater is electrically coupled to a first heater section H1. In such embodiments, the exhalation heater receives power when the first heater section H1 receives power.

[0106] Circuit diagram 2500 advantageously allows control of segmented heaters using a single power supply and a patient-end temperature sensor (e.g., a thermistor). For example, Circuit diagram 2500 can be implemented in a system that does not include a temperature sensor in the intermediate connector connecting the first heater segment H1 to the second heater segment H2. Circuit diagram 2500 can be implemented using a control system configured to change the switching of a MOSFET pair to heat either the first heater segment H1 (e.g., the inner loop HW1 of the inspiratory limb) or the first or second heater segment H1, H2 (e.g., the outer loop HW2 of the inspiratory limb with the inspiratory and extension limbs), which will be described in detail below. HW2 may include both H1 and H2, i.e., the entire heating circuit along the entire tube.

[0107] Detection of the connecting extension of the inspiratory limb Figure 5 shows a block diagram of an exemplary system 500 configured to use an extension detection module 502 to detect the presence of an extension of the inspiratory limb and to supply power to the heater wires in the inspiratory limb (e.g., a first segment of the inspiratory limb), the extension of the inspiratory limb (e.g., a second segment of the inspiratory limb), and / or the expiratory limb. As described with reference to, for example, Figures 3A, 3B, 4, 8A, and 8B, a logic module 504 (which may comprise hardware, software, or some combination of both) can be configured to provide logic that enables the switching described with respect to various control modes. The logic module 504 can receive signals from an integrated circuit 506, which is part of the respiratory humidification system 100. In some embodiments, the logic module 504 is software, either all or part, embedded 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 can be configured to detect zero-level crossovers, i.e., points where voltage or current transitions from positive to negative or vice versa, and to 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 supplied to the inhalation heater wire (INSP HW), the exhalation heater wire (EXP HW), or both.

[0108] In some embodiments, the system 500 may include an extension detection module 502 configured to detect whether a 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.

[0109] In some embodiments, the extension detection module 502 can be configured to detect the presence of the second section 202b by switching both the inhalation and exhalation circuits on and detecting whether a hardware overcurrent event is detected. If 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 using current measurements to detect the resistance of identification resistors or heater wires within each section. Based at least in part on current measurements in various sections, the extension detection module 502 can generate an "enable signal" if the current measurements differ for various cycles in which various control modes are implemented as described above with reference to Figures 3A, 3B, 4, 8A, and 8B.

[0110] Sensor circuit Figures 6A and 6B show exemplary circuit diagrams within the respiratory humidification system 100, where the circuit 600 is configured to read data from two sensors R1 and R2. Referring to Figures 6A and 6B, sensors R1 and R2 are represented using resistors, but any suitable type of sensor can be used, for example, temperature sensors, humidity sensors, flow sensors, oxygen sensors, etc., without limitation. In some embodiments, the sensors may be temperature sensors such as thermistors. In such embodiments, sensors R1 and R2 represent a first thermistor at the intermediate connector 214 and a second thermistor at the patient end of the respiratory circuit 200 (e.g., the patient end connector), respectively. The two thermistors R1 and R2 can be measured using two wires within the respiratory circuit 200, with the circuit 600 together with a current or voltage source and switch in the humidifier control device 122. This explanation, with reference to Figures 6A and 6B, pertains to thermistors, but is also applicable to other suitable sensors that affect the voltage and / or current supplied to the associated circuit.

[0111] To selectively read sensors R1 and R2, current is supplied via lines 602 and 604 in either polarity. To measure patient-end sensor R2, the humidifier control device 122 sets a switch to ground the upper current source. Current then flows from the bottom current source through R2 and through the switch to ground. Diode D1 prevents the current from flowing through R1. The humidifier control device 122 can be configured to measure the voltage drop from the bottom current source to ground and derive the resistance of sensor R2 based at least in part on the supplied current and the measured voltage. To measure sensor R1 positioned in the intermediate connector 214, the humidifier control device 122 can read patient-end sensor R2 and record the result. The humidifier control device 122 can then set a switch to ground the bottom current source. Current then flows from the upper current source through R1 and R2 and through the switch to ground. The humidifier control device 122 can be configured to measure the voltage drop from the upper current source to ground and derive the resistance of sensor R1 based at least in part on the supplied current, the measured voltage, and the recorded result from the measurement of the resistance of R2. In some embodiments, the voltage drop across D1 is taken into account when deriving the resistance of R1. In the embodiment shown in Figure 6A, the temperature of diode D1 can be calculated by placing D1 near R1, and this temperature can be used to calculate the voltage drop across D1. One possible advantage of the configuration shown in Figure 6A is that the measurement of sensor R2 at the patient end may be more accurate because the measurement is performed without passing through a diode, as illustrated in the embodiment of Figure 6B. Passage through a diode can introduce uncertainty or error.

[0112] In some embodiments, an additional diode D2 can be added to the intermediate connector 214, as shown in Figure 6B. In such embodiments, the humidifier control device 122 can be configured to measure sensors R1 and R2 in the same manner as in the embodiments shown in Figure 6A and described above. The difference is that when measuring sensor R1, diode D2 obstructs the flow of current through R2, so that current flows through R1 and D1 but not through R2. In this way, the measurement of sensor R1 can be substantially isolated or separated from the measurement of sensor R2. Similar to the derivation of the resistance of sensor R1, the voltage drop across diode D2 can be taken into account when deriving the resistance of sensor R2. By placing D1 and D2 near R1, the temperature of the diodes can be calculated, and this temperature can be used when calculating the voltage drop across D1 and D2, respectively.

[0113] In certain embodiments, measurements of sensors R1 and R2 are performed by software running on a control device connected to the circuit in Figure 6A or Figure 6B. The direction and amount of current supplied to the circuit can be controlled by such software. Accurate measurements of the resistances of sensors R1 and R2 can be obtained, for example, by measuring the voltage using an analog-to-digital converter. To minimize or prevent the effects of changes caused by diodes D1 and / or D2, the software can supply two different currents (I1 and I2) in the same direction. This yields two different voltage readings (V1 and V2) corresponding to the two different currents (I1 and I2). Using these two voltages and currents, the software can determine the voltage drop across diodes D1 and D2, and the resistances with respect to sensors R1 and R2. With respect to sensor R1, for example, the voltage drop can be calculated by the following formula: Vdrop = ((V1*I2-V2*I1) / ((V1-V2) / R2+I2-I1)). The resistance of sensor R1 can be calculated using the following formula: R1 = (V2 - Vdrop) / (I2 - V2 / R2). In one embodiment, the calculated Vdrop has a certain error from the measured Vdrop, and this error is corrected by software. In one embodiment, Vdrop is increased by only about 15% as error compensation.

[0114] In some embodiments, sensors R1 and R2 (e.g., thermistors) can be omitted. In such embodiments, more precise sensors can be included in the system. This may allow the use of symmetrical intermediate connectors (e.g., mechanically and electrically independent connectors). For example, the intermediate connector can be physically connected in two ways and can also operate to mechanically couple the intake limb sections and to direct power to the target section of the sectioned heater. In some embodiments described herein, diodes and other electrical components may be configured so that a control algorithm provides power to an undesirable portion of the sectioned heater if the connector is plugged in the reverse direction.

[0115] Figure 7 shows an exemplary circuit diagram within 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 at least in part based on the temperature effect of the pn junctions at the base and emitter terminals of the transistors. The switching of current in the humidifier control device 122 may be the same as that relating to the circuits described with reference to Figures 6A and 6B, or it may be an alternating configuration as shown. For example, the illustrated switching configuration uses two switches with two power supplies and two grounds to selectively supply power to a wire. In the first configuration, the upper switch electrically connects the upper power supply to wire 702, and the bottom switch electrically connects the ground to wire 704. In the second configuration, the upper switch electrically connects the ground to wire 702, and the bottom switch electrically connects the bottom power supply to wire 704. By using transistors Q1 and Q2 as temperature sensors, the transistors provide the functions of both temperature sensors and diodes, thus eliminating the need for diodes.

[0116] Respiratory circuit hardware configuration Figure 8A shows an illustrative diagram of a hardware configuration 800 relating to 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 may include a humidifier 108 configured to couple the wiring of heater wires HW1 and HW2 via switches or relays S3 and S4, and also to couple the 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 the wiring for sensors 204a, 204. As described with reference to Figures 4B to 4D, and as described with reference to Figure 4A, switches S3, S4 can be used to selectively control the power from the expiratory limb 210 to the heater wire HW2. In some embodiments, both switches S3 and S4 are in the open position by default and are closed when the appropriate tube (e.g., an inspiratory or expiratory limb with the appropriate identification resistor) is connected to the humidifier 108. In this way, the hardware configuration 800 can be used to supply power to the heater wires HW1 and / or HW2. Regardless of whether heater wire HW2 is receiving power, 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 and 206b receive power. In the illustrated embodiments, heater wire HW2 can supply power when heater wire HW1 is controlled in either the first or second mode. It should be understood that the heater wire HW2 for the expiratory limb can be selectively controlled, while the heater wire HW1 for the inspiratory limb is in a single mode. For example, when the inspiratory limb heater wire HW1 is controlled in a first mode (or second mode), the expiratory limb heater wire HW2 can alternate between receiving power and not receiving power, at least in part, based on the operation of switches S3 and S4, without changing the control mode of the heater wire HW1.Similarly, while the inspiratory limb heater wire HW1 is changed between the first and second modes, the expiratory limb heater wire HW2 can remain in a state that receives power.

[0117] Hardware configuration 800 may include an intermediate printed circuit board (PCB) 214 containing 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 the heat generated by diodes D1 and D3 and reduce the impact on sensor 204a. Hardware configuration 800 may include a patient end PCB 804 having two heater wires and one sensor 204b, with heater wire 206b being electrically directly coupled. In a first operating mode, power can be supplied to HW1 such that current flows through heater wire 206a and diode D1, while substantially no current flows through heater wire 206b (e.g., less than 1% of the current flowing through heater wire 206a flows through heater wire 206b). In a second operating mode, power can be supplied to HW1 such that current flows through heater wires 206a and 206b. The first and second operating modes can be controlled, at least in part, by the direction of the current passing through the heater wire HW1.

[0118] In certain embodiments, diodes D2 and D4 can be added to the hardware configuration 800, as shown in Figure 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 and D4 are positioned close to each other so as to reduce the differences in effects caused by different ambient temperatures under the same or similar ambient conditions. In other respects, the circuit 200 operates similarly to the circuit shown in Figure 8A.

[0119] In some embodiments, comparing Figure 8A and Figure 8B, omitting diode D4 improves sensing reliability at the patient end. For example, the diode may fail in the open position. If diode D4 fails in the open position, it may become impossible to read the patient end temperature. In the circuit shown in Figure 8A, even if diode D3 fails, the patient end sensor 204b can still be read. Omitting diode D2 can have similar advantages.

[0120] In some embodiments, the sensor cartridge 802 may be located inside or outside the humidification system 100.

[0121] Exemplary segmented inspiratory limb with connector having microcontroller Figure 9 shows an exemplary embodiment of a respiratory humidification system 100, which utilizes a microcontroller located in an intermediate connector 214 to measure data for controlling heating and to read sensor values ​​at the inspiratory limb 202. In some embodiments, one or more microcontrollers can be incorporated into the sensor cartridge, humidifier, intermediate connector 214, or any combination thereof. When incorporated, for example, into the sensor cartridge, the microcontroller provides similar functionality to that described herein. The illustrated exemplary embodiment uses one heater wire connected to VN as a common reference, and connects two heater wires HW1, HW2 and a sensor wire to the common reference. The exemplary embodiment also converts the readings from both sensors 204a, 204b into digital signals at the signal intermediate connector 214 and transmits them to the humidifier control device 122. This can reduce or prevent isolation issues by providing a common reference point as the reference for sensors 204a, 204 and transmitting digital parameter readings. The readings can pass through an optocoupler in the control unit 122, which isolates the signal as described herein with reference to Figure 12. Using this exemplary embodiment, two independent control channels can be used to heat only the first section 202a, or the first and second sections 202a, 202b of the intake limb, to provide desired, selected, or predetermined heating control.

[0122] Figure 10 shows a block diagram of an 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 signals can be transmitted to the humidifier control unit 122 on a single data line. To provide temperature data, the data line can be used to enable communication between the microcontroller and the humidifier control unit 122. Power can be supplied to the microcontroller using the data line by pulling the data line high in the humidifier control unit 122 when no data is being transmitted. The power module and data line converter may include a capacitor and a diode, so that the capacitor is charged when the data line is high. When the data line is used for communication, the charged capacitor can be used to supply power to the microcontroller. A schematic diagram of an exemplary power module and data line converter is shown in Figure 11.

[0123] Temperature sensing using this configuration can be achieved by driving a thermistor using a current or voltage source located in the intermediate connector 214, which can then be read by a microcontroller. This can be done, for example, using a transistor or operational amplifier. Data line communication can be achieved using a time slot-based method, where each logic level can be transmitted and read within a predetermined time slot. In this way, bidirectional communication between the humidifier control device 122 and the microcontroller can be enabled using a single wire.

[0124] The humidifier control device 122 may include a DC power supply referenced to VN. It may also include a capacitor that can charge when the heater wire is on and supply power to the microcontroller while the heater wire is switched off. The humidifier control device 122 may include a dual optocoupler circuit 1200, as shown in Figure 12. The dual optocoupler circuit can be used to isolate signals and enable bidirectional data communication between the control device 122 and the power supply.

[0125] In some embodiments, calibration data can be stored in the microcontroller and retrieved when the 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.

[0126] Segmented inspiratory limbs equipped with digital temperature sensors Figure 13 shows a schematic of an exemplary respiratory humidification system 100, which incorporates digital temperature sensors 204a and 204b for use with a breathing circuit 200, the breathing circuit 200 having an intermediate connector 214 that connects a first section 202a and a second section 202b to form an inspiratory limb 202. Similar to the design described with reference to Figure 9, the digital temperature sensors 204a and 204b can utilize a single line for communication and power supply, simplifying the circuit design and reducing the amount of wire used in system 100. The design shown in Figure 13 allows the temperature sensor and data communication to be implemented as a single chip rather than a combination of circuit elements, which can be desirable.

[0127] Intermediate connector board Figures 14A and 14B show an exemplary intermediate PCB 250 of the intermediate connector 214, with each figure showing two sides of the intermediate PCB 250. The intermediate PCB 250 includes connection pads 252, 254 for the heater wire and sensor connection wire. The connection pads 252, 254 are located on both sides of the intermediate PCB 250 to facilitate connection with the heater wire, which is spirally wound around the intake leg.

[0128] The intermediate PCB 250 includes sensor connection pads 256 for sensors such as thermistors or other temperature measuring components, or humidity sensors or flow sensors. Sensors can be coupled to diodes (e.g., diode D3 as described with reference to Figure 8B) via signal connection pads 258 located on the intermediate PCB 250. As illustrated, the intermediate PCB 250 includes gaps 262 configured to insulate the sensors from other electrical components and tracks. In some embodiments, the gaps 262 can be filled with insulating material to further insulate the sensors connected to the sensor connection pads 256. Furthermore, the intermediate PCB 250 can be configured to position sensors away from other active and / or passive electrical components, for example, by projections 257.

[0129] The intermediate PCB 250 includes a power connection pad 260 for a diode electrically coupled to the heater wires via an electrical track on the intermediate PCB 250. The diode may be diode D1 as described with reference to Figure 3B, Figure 6B, or Figure 8B. The power connection pad 260 can be electrically and thermally coupled to the heat sink 264, which helps dissipate heat and reduces or minimizes its impact on the accuracy of parameter readings of the sensor coupled to the sensor connection pad 256.

[0130] Figures 14C and 14D show exemplary embodiments of an intermediate connector 214 comprising an intermediate PCB 250 and an intermediate connecting element 263. The intermediate connecting element 263 can be configured to deliver a portion of the humidified gas flowing through the intake limb through a conduit formed by the intermediate connecting element 263. A sensor on the intermediate PCB 250 can then provide a signal corresponding to parameters of the gas flowing through the intermediate connecting element 263, which represent at least one characteristic of the humidified gas in the intake limb at that time (e.g., temperature, humidity, flow rate, oxygen content, etc.). In some embodiments, the intermediate connecting element 263 is configured to provide mechanical support for the intermediate PCB 250 to position the intermediate PCB 250 within the intake limb. In some embodiments, the intermediate connecting element 263 is configured to provide mechanical support for joining two sections of the intake limb in or near the intermediate connector 214.

[0131] The intermediate connector 214 includes a first connection pad 252 on the first face of the intermediate PCB 250 and a second connection pad 254 on the second face of the intermediate PCB 250 (the opposite face of the intermediate PCB 250). As described herein, the first and second connection pads 252, 254 can each be configured to provide electrical contacts for heater wires in the first and second sections of the segmented intake limb. In some embodiments, the heater wires in the sections of the intake 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.

[0132] In some embodiments, the intermediate PCB 250 includes a first portion extending across the lumen formed by the intermediate connecting element 263 along a diameter or code line, thereby the portion of the intermediate PCB 250 generally crosses at least a portion of the gas flow path. The first portion of the intermediate PCB 250 can be overmolded by an overmolding composition. The intermediate PCB 250 may include a second portion 251 adjacent to the first portion, the second portion 251 projecting outward from the outside of the intermediate connecting element 263 toward the lumen. The second portion 251 of the intermediate PCB 250 includes one or more connecting pads 252 configured to receive one or more wires from the first segment of the inspiratory limb. The intermediate PCB 250 may include a third portion 253 adjacent to the first portion, the third portion 253 projecting outward from the outside of the intermediate connecting element 263 toward the lumen and in the opposite direction to the second portion 251. The third portion 253 may include one or more connection pads 254 located in an intermediate PCB 250 configured to receive one or more wires from a second segment of the inspiratory limb. The intermediate PCB 250 includes one or more conductive tracks configured to electrically couple one or more connection pads 252 of the second portion 251 to one or more connection pads 254 of the third portion 253, and also to provide an electrical connection between the wires in the first segment of the inspiratory limb and the wires in the second segment.

[0133] In some embodiments, the intermediate PCB 250 can limit the number of contact pads for the wires to four. In such embodiments, the wires can overlap the tube to maintain the continuity of the tube. In such embodiments, it may be beneficial to maintain the orientation and / or order of the wires.

[0134] Figure 34 shows exemplary embodiments of intake and extension limbs 3405 and 3410, each comprising a diode 3420 and heater wires 3402 and 3404 directly coupled to one another. In some embodiments, the intermediate connector 214 can be configured to include a diode for direct connection of the wires 3402 and 3404. For example, the wires 3402 and 3404 can be laser-cut so that the wires 3402 and 3404 are exposed. The diode 3420 can be configured to cross the heater wires 3402 and 3404 and contact the wires in a location where there is no sensor and no intermediate PCB, as described herein. In such a configuration, the intake and extension limbs can be advantageously configured to have no unheated sections. Similarly, this configuration can reduce or eliminate condensation, dendrite growth, electrical short circuits of the heater wires or sensing wires, printed circuit boards in the intermediate connector, circuit damage, and / or flow resistance.

[0135] Patient end connector board Figure 15A shows an exemplary patient end PCB 270 of the patient end connector 804. The patient end PCB 270 includes connection pads 272 for the heater wire and sensor connection wire. The connection pads 272 are configured to be on only one side of the patient end PCB 270 and connect to the helically wound heater wire and signal wire from the inspiratory limb. Two of the connection pads 272 can be electrically directly coupled to each other as an electrical passage. The heater wire can be coupled to the electrically directly coupled connection pads 272. The remaining two connection pads 272 can be electrically coupled to the sensor connection pad 274. The electrical tracks 278 to and from the sensor connection pad 274 can be configured to reduce or minimize the width of the tracks and increase or maximize the length of the tracks to insulate the sensor connected to the sensor connection pad 274. The patient end PCB 270 may include a projection 276 similar to that described with reference to the PCB 250 shown in Figures 14A and 14B. The protrusion 276 can be configured to further insulate the sensor from the effects of current and components at the patient end PCB 270.

[0136] Figures 15B–15E show exemplary embodiments of the patient end connector 804. Figures 15B and 15D show exemplary embodiments of the patient end PCB 270 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.

[0137] Segmented inspiratory limb placement limiter Figures 16A–16E show exemplary embodiments of a placement limiter 280 for a segmented inspiratory limb 202. Figure 16A shows an exemplary placement limiter 280, which is 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 having a groove 288, in which a grommet 294 can be positioned. The placement limiter 280 can be configured to prevent or reduce the possibility of an intermediate connector or a segmented connection point of the inspiratory limb 202 (e.g., where an intermediate PCB 250 is located) entering the incubator 290 through the 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 placement limiter 280 is configured to substantially fix the position of the intermediate PCB 250 within a target distance or a desired distance from the incubator, or at other such point defining a different temperature environment. The target distance or desired distance may be about 20 cm or less, about 10 cm or less, about 5 cm or less, or about 0 cm. Figure 16B shows an exemplary placement limiter 280 used with a bubble tube 202, where the placement limiter is located at a distance d1 from the inlet 292 to the incubator 290.

[0138] Figure 16C shows an exemplary embodiment of the placement limiter 280 configured to clip or secure to an object such as clothing, a blanket, or another object separate from the patient. The placement limiter 280 is fixed to the inspiratory limb 202 and configured to be movable along the inspiratory limb 202 to adjust the position of the inspiratory limb 202. Figure 16D shows the inspiratory limb 202 with the placement limiter 280 in use with the incubator 290 to prevent or block the entry of the intermediate PCB connector 250 into the incubator 290. Figure 16E shows the inspiratory limb 202 with the placement limiter 280 in use with a patient, where the placement limiter 280 is fixed to the patient's blanket to prevent or block the movement of the inspiratory limb 202 relative to the patient and / or blanket. The placement limiter 280 can also be used with an expiratory limb or other medical tubes used in connection with a gas delivery system.

[0139] Sectionalized medical piping for use with respiratory humidification systems Figure 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 Figure 1. The composite tube 1201 can be used as an inspiratory limb 202 and can be configured to provide thermally beneficial properties that help prevent gas condensation along the tube, as described herein. The composite tube 1201 includes a plurality of elongated members that are wound and joined to form a path, where the plurality of elongated members may include one or more of the heater wires described herein. Based at least in part on the heater wires being embedded in the wall of the composite tube 1201, the use of the composite tube 1201 as an inspiratory limb 202 can reduce condensation and rainout and maintain a more desirable or target temperature profile along the length of the inspiratory limb 202. The wall of the composite tube can provide a greater thermal mass, which is more resistant to temperature changes and enhances the insulating effect of the wall against the ambient temperature outside the limb 202. As a result, the temperature along the length of the limb 202, including any number of different temperature environments, can be controlled more precisely, and less power or energy can be lost when controlling the temperature of the gas delivered to the patient. In some embodiments, the composite tube 1201 can also be used as the expiratory limb 210.

[0140] Generally, the composite pipe 1201 comprises a first elongated member 1203 and a second elongated member 1205. The term "member" is broad and should be interpreted in its usual and customary sense to those skilled in the art (i.e., not limited to any particular or specialized sense), and includes, but is not limited to, a whole, a whole component, and different components. Therefore, while Figure 17A shows an embodiment formed from two different components, it should be understood that in other embodiments, the first elongated member 1203 and the second elongated member 1205 could also represent regions within the pipe formed from a single material. Thus, the first elongated member 1203 could be a hollow portion of the pipe, and the second elongated member 1205 could be a structural support or reinforcing portion of the pipe that adds structural support to the hollow portion. As described herein, the hollow portion and the structural support portion may have a helical configuration. The composite tube 1201 can be used to form the inspiratory limb 202 and / or expiratory limb 210 as described herein, the coaxial tube as described below, or any other tube as described elsewhere in this disclosure.

[0141] In this example, the first elongated member 1203 comprises a helically wound hollow body, forming at least a portion of an elongated tube having a longitudinal axis LA-LA, and also comprises a lumen 1207 extending along the longitudinal axis LA-LA. In at least one embodiment, the first elongated member 1203 is a tube. Preferably, the first elongated member 1203 is flexible. Furthermore, the first elongated member 1203 is preferably transparent, or at least translucent or semi-opaque. Some degree of light transmission allows a caregiver or user to inspect the lumen 1207 for obstruction or contaminants, or to confirm the presence of moisture. A variety of plastics, including medical-grade plastics, are suitable for the body of the first elongated member 1203. Examples of suitable materials include polyolefin elastomers, polyether block amides, thermoplastic copolymer elastomers, EPDM-polypropylene mixtures, and thermoplastic polyurethanes.

[0142] The hollow structure of the first elongated member 1203 contributes to the thermal insulation properties of the composite tube 1201. The insulated tube 1201 is desirable because it prevents or reduces heat loss as described herein. This allows the tube 1201 to deliver gas from the heater-humidifier to the patient while substantially maintaining the regulated state of the gas with less or minimal energy loss.

[0143] In at least one embodiment, the hollow portion of the first elongated member 1203 is filled with gas. The gas may be air, which has a low thermal conductivity (2.62 × 10⁻¹⁰ at 300K). -2 It is desirable due to its high viscosity (W / m·K) and very low cost. Furthermore, it is advantageous that a gas with higher viscosity than air can be used. This is because higher viscosity reduces convective heat transfer. Therefore, argon (17.72 × 10⁻¹⁰ at 300K) is desirable. -3 W / m·K), krypton (9.43 × 10 at 300K) -3 (W / m·K), and xenon (5.65 × 10 at 300K) -3 Gases such as W / m·K can enhance the thermal insulation performance. These gases are non-toxic, chemically inert, flame-retardant, and commercially available. The hollow portion of the first elongated member 1203 can be sealed at both ends of the tube to substantially retain the gas inside. Alternatively, the hollow portion may be a secondary pneumatic connection line, such as a pressure sample line for transmitting pressure feedback from the patient end of the tube to a control device. The first elongated member 1203 can be optionally perforated. For example, the surface of the first elongated member 1203 may be perforated on the outward-facing surface opposite to the lumen 1207. In another embodiment, the hollow portion of the first elongated member 1203 is filled with a liquid. Examples of liquids include water or other biocompatible liquids with high heat capacity. For example, nanofluids can be used. An exemplary nanofluid with suitable heat capacity includes water and nanoparticles of a substance such as aluminum.

[0144] The second elongated member 1205 is also wound spirally and joined to the first elongated member 1203 between adjacent turns of the first elongated member 1203. The second elongated member 1205 forms at least a portion of the lumen 1207 of the elongated tube. The second elongated member 1205 acts as a structural support for the first elongated member 1203.

[0145] In at least one embodiment, the second elongated member 1205 is wider at the base (proximal to the lumen 1207) and narrower at the top. For example, the second elongated member may be generally triangular, generally T-shaped, or generally Y-shaped. However, any shape that matches the contour of the corresponding first elongated member 1203 is suitable.

[0146] Preferably, the second elongated member 1205 is flexible to facilitate the bending of the tube. Preferably, 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 modulus of elasticity of the second elongated member 1205 is preferably 30-50 MPa (or about 30-50 MPa). The modulus of elasticity of the first elongated member 1203 is less than that of the second elongated member 1205. The second elongated member 1205 may be solid or nearly solid. Furthermore, the second elongated member 1205 can encapsulate or house a conductive material, such as a filament, particularly a heating filament, or a sensor (not shown). The heating filament can minimize the low-temperature surface where condensation from humid air may occur. Furthermore, a heating filament can be used to alter the temperature profile of the gas within the lumen 1207 of the composite tube 1201. 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 mixtures, and thermoplastic polyurethanes. In certain embodiments, the first elongated member 1203 and the second elongated member 1205 may be formed from the same material. The second elongated member 1205 may also be formed from a material of a different color from the first elongated member 1203, and may be transparent, translucent, or opaque. For example, in one embodiment, the first elongated member 1203 may be formed from a transparent plastic, and the second elongated member 1205 may be formed from an opaque blue (or other color) plastic.

[0147] This spirally wound structure, comprising a flexible hollow body and an integral support, can provide compressive resistance while ensuring that the tube wall is flexible enough to allow bending at a short radius without buckling, blockage, or collapse. Preferably, the tube can be bent around a 25 mm diameter metal cylinder without buckling, blockage, or collapse, as defined in the test for increase in flow resistance with bending according to ISO 5367:2000(E). Furthermore, this structure can provide a smooth surface (hole) of the lumen 1207, which helps prevent deposit formation in the tube and improves gas flow. The hollow body has been found to improve the thermal insulation properties of the tube while keeping it lightweight.

[0148] As described 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 as at least an inspiratory tube.

[0149] Figure 17B shows the upper longitudinal section of the exemplary composite tube 1201 of Figure 17A. Figure 17B has the same orientation as Figure 17A. This example further illustrates the hollow shape of the first elongated member 1203. As seen in this example, the first elongated member 1203 forms multiple air bubbles in the longitudinal section. A portion 1209 of the first elongated member 1203 overlaps with an adjacent winding of the second elongated member 1205. A portion 1211 of the first elongated member 1203 forms the wall (hole) of the lumen.

[0150] It was unexpectedly 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. Therefore, in certain embodiments, adjacent bubbles are separated by gaps 1213. Furthermore, certain embodiments include increasing the thermal resistance (R value) and thus reducing the thermal conductivity of the composite tube 1201 by providing gaps 1213 between adjacent bubbles. It was also found that this gap configuration improves the flexibility of the composite tube 1201 by allowing bending at a shorter radius. As shown in Figure 17B, the T-shaped second elongated member 1205 can help maintain gaps 1213 between adjacent bubbles. Nevertheless, in certain embodiments, adjacent bubbles are in contact. For example, adjacent bubbles can be joined together as a single unit.

[0151] One or more conductive materials can be arranged within the second elongated member 1205 to heat or sense the gas flow. In this example, two heating filaments 1215 are encapsulated within the second elongated member 1205, each on one side of the “T”-shaped vertical portion. The heating filaments 1215 include conductive materials such as aluminum (Al) and / or copper (Cu) alloys or conductive polymers. Preferably, the material forming the second elongated member 1205 is selected so as not to react with the metal in the heating filaments 1215 when they reach their operating temperature. The filaments 1215 may be positioned away from the lumen 1207 so as not to be exposed to the lumen 1207. At one end of the composite tube, several pairs of filaments may be formed as an articulated loop.

[0152] In at least one embodiment, multiple filaments are arranged within a second elongated member 1205. The filaments can be electrically connected to one another and share a common rail. For example, a first filament, such as a heating filament, can be arranged on a first side of the second elongated member 1205. A second filament, such as a sensing filament, can be arranged on a second side of the second elongated member 1205. A third filament, such as a grounding filament, can be arranged between the first and second filaments. The first, second, and / or third filaments can be connected to one another at one end of the second elongated member 1205.

[0153] Figure 17C shows a longitudinal cross-section of the cellular structure in Figure 17B. As shown, a portion 1209 of the first elongated member 1203 overlapping an adjacent winding of the second elongated member 1205 is characterized by a certain degree of bonding region 1217. A larger bonding region improves the tube's resistance to delamination at the interface between the first and second elongated members. As an addition or alternative, the shape of the bead and / or cellular structure can be adapted to increase the bonding region 1217. For example, Figure 17D shows a relatively small bonding region on the left. Also, Figure 19B shows an even smaller bonding region. In contrast, Figure 17E has a much larger bonding region than that shown in Figure 17D, due to the size and shape of the bead. Figures 19A and 19C also show larger bonding regions. These figures will be discussed in more detail below, respectively. While the configurations in Figures 17E, 19A, and 19C may be preferred in certain embodiments, it should be understood that in other embodiments, other configurations, including those in Figure 17D, Figure 19B, and other variations, may also be used if desired.

[0154] Figure 17D shows a longitudinal section of the upper part of another composite tube. Figure 17D has the same orientation as Figure 17B. This example further illustrates the hollow shape of the first elongated member 1203 and how the first elongated member 1203 forms multiple air bubbles in the longitudinal section. In this example, the air bubbles are completely separated from each other by gaps 1213. A generally triangular second elongated member 1205 supports the first elongated member 1203.

[0155] Figure 17E shows a longitudinal cross-section of the top of another composite tube. Figure 17E has the same orientation as Figure 17B. In the example of Figure 17E, the heating filaments 1215 are positioned further apart from each other than the filaments 1215 in Figure 17B. It has been found that heating efficiency can be improved by increasing the space between heating filaments. Certain embodiments include this implementation. Heating efficiency represents the ratio of the amount of heat entering the tube to the amount of energy leaving or recoverable from the tube. Generally, the greater the energy (or heat) dissipated from the tube, the lower the heating efficiency. For improved heating performance, the heating filaments 1215 can be positioned evenly (or nearly evenly) along the holes in the tube. Alternatively, the filaments 1215 can be positioned at the ends of a second elongated member 1205, which may allow for simpler manufacturing.

[0156] Next, we refer to Figures 18A to 18G, which show exemplary configurations of the second elongated member 1205. Figure 18A shows a cross-section of the 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 of the second elongated member 1205 can also be used, including variations of the T-shape and a triangular shape, as described below.

[0157] Figure 18B shows another exemplary second elongated member 1205 having a T-shaped cross-section. In this example, the heated filament 1215 is embedded in notches 1301 of the second elongated member 1205 on each side of the vertical portion of the "T" shape. In some embodiments, the notches 1301 can be formed in the second elongated member 1205 during extrusion. Alternatively, the notches 1301 can also 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 heated filament 1215 immediately after extrusion, while the second elongated member 1205 is relatively flexible, as the heated filament 1215 is pushed or pulled into (mechanically fixed) the second elongated member 1205. Alternatively, one or more heating filaments can be attached to the bottom of an elongated member (e.g., by bonding, joining, or partially embedding) so that the filaments are exposed to the lumen of the tube. In such embodiments, it may be desirable to include the filaments in insulation to reduce the risk of ignition when a flammable gas such as oxygen is passed through the lumen of the tube.

[0158] Figure 18C shows a cross-section of yet another exemplary second elongated member 1205. The second elongated member 1205 has a generally triangular shape. In this example, the heating filaments 1215 are embedded on both sides of the triangle.

[0159] Figure 18D shows a cross-section of yet another exemplary second elongated member 1205. The second elongated member 1205 comprises four grooves 1303. The grooves 1303 are depressions or recesses in the cross-sectional shape. In some embodiments, the grooves 1303 can facilitate the formation of notches (not shown) for embedding filaments (not shown). In some embodiments, the grooves 1303 facilitate the positioning of filaments (not shown) that are pushed or pulled into the second elongated member 1205 and thereby embedded. In this example, the four starting grooves 1303 facilitate the arrangement of up to four filaments, for example, four heating filaments, four sensing filaments, two heating filaments and two sensing filaments, three heating filaments and one sensing filament, or one heating filament and three sensing filaments. In some embodiments, the heating filaments can be positioned on the outside of the second elongated member 1205. The sensing filaments can be positioned on the inside.

[0160] Figure 18E shows a cross-section of yet another exemplary second elongated member 1205. The second elongated member 1205 has a T-shaped cross-section and a plurality of grooves 1303 for arranging heating filaments.

[0161] Figure 18F shows a cross-section of yet another exemplary second elongated member 1205. Four filaments 1215 are encapsulated within the second elongated member 1205, two on each side of the “T”-shaped vertical section. The filaments are encapsulated within the second elongated member 1205 because the second elongated member 1205 was extruded around the filaments, as will be 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 several grooves 1303. Since the heating filaments 1215 are encapsulated within the second elongated member 1205, the grooves 1303 are not used to facilitate the formation of notches for embedding the heating filaments. In this example, the grooves 1303 can facilitate the separation of the embedded heating filaments, which facilitates the peeling of individual cores, for example, when terminating the heating filaments.

[0162] Figure 18G shows a cross-section of yet another exemplary second elongated member 1205. The second elongated member 1205 has a generally triangular shape. In this example, the shape of the second elongated member 1205 is similar to that of Figure 18C, but four filaments 1215 are encapsulated within the second elongated member 1205, all of which are centrally located in the lower third of the second elongated member 1205 and arranged along a generally horizontal axis.

[0163] As explained above, it is sometimes desirable to increase the distance between filaments to improve heating efficiency. However, in some embodiments, when the heating filament 1215 is incorporated into the composite tube 1201, the filament 1215 can be positioned relatively centrally within the second elongated member 1205. This centralized position provides robustness of the composite piping for reuse. This is partly because such a position reduces the likelihood of the filament breaking during repeated bending of the composite tube 1201. Also, by centralizing the filament 1215, the filament 1215 is coated with an insulating layer and kept away from the gas path, thus reducing the risk of ignition accidents.

[0164] As described above, some of the examples above illustrate the appropriate arrangement of the filaments 1215 within the second elongated member 1205. In the aforementioned examples with multiple filaments 1215, the filaments 1215 are generally aligned along the horizontal axis. Alternative configurations are also suitable. For example, two filaments can be aligned along the vertical axis or along the diagonal axis. Four filaments can also be aligned along the vertical axis or along the diagonal axis. Four filaments can also be aligned in a cross shape, with one filament positioned at the top of the second elongated member, one filament at the bottom of the second elongated member (near the lumen of the tube), and two filaments positioned at the left and right bar portions of a "T" or "Y" shape, or at both ends of the base of a triangle.

[0165] Tables 1A and 1B show some preferred dimensions of the medical tubes described herein, and some preferred ranges for these dimensions. Dimensions represent the transverse cross-section of the tube. In these tables, lumen diameter represents the inner diameter of the tube. Pitch represents the distance between two repeating points measured axially along the tube, i.e., the distance between the tips of adjacent "T"-shaped vertical portions 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 tube. Bead height represents the maximum height of the second elongated member from the lumen of the tube (e.g., the height of the "T"-shaped vertical portion). Bead width represents the maximum width of the second elongated member (e.g., the width of the "T"-shaped horizontal portion). Bubble thickness represents the thickness of the bubble wall.

[0166] [Table 1A]

[0167] [Table 1B]

[0168] Tables 2A and 2B provide exemplary ratios between the dimensions of the pipe shapes for the pipes described in Tables 1A and 1B, respectively.

[0169] [Table 2A]

[0170] [Table 2B]

[0171] The following table shows some exemplary properties of the composite tube (represented as "A") having a heating filament incorporated inside the second elongated member as described herein. For comparison, the properties of the Fisher & Paykel model RT100 disposable corrugated tube (represented as "B"), which has a heating filament spirally wound inside the tube's bore, are also shown.

[0172] The flow resistance (RTF) was measured according to Appendix A of ISO 5367:2000(E). The results are summarized in Table 3. As can be seen below, the RTF for the composite tube is smaller than the RTF for the Model RT100 tube.

[0173] [Table 3]

[0174] Condensation or "rainout" inside the tube represents the weight of condensate collected per day at room temperature of 18°C ​​with a gas flow rate of 20 L / min. Humidified air was continuously flowed from the chamber through the tube. The weight of the tube was recorded before and after each day of testing. Three consecutive tests were conducted, with the tube dried between each test. The results are shown in Table 4. These results showed that rainout was considerably lower in the composite tube than in the model RT100 tube.

[0175] [Table 4]

[0176] The power requirements represent the power consumed during the condensation test. In this test, the ambient air was maintained at 18°C. The humidification chamber (see, for example, humidification chamber 114 in Figure 1) was powered by an MR850 heater base. Power was supplied to the heating filament inside the tube 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 maintain the output temperature was recorded, and the power generated was calculated. The results are shown in Table 5. These results show that composite tube A uses considerably more power than tube B. This is because tube B uses a helical heating filament inside the tube bore to heat the gas from 37°C to 40°C. The composite tube does not tend to heat the gas rapidly because the heating filament is inside the tube wall (embedded in a second elongated member). Rather, the composite tube is designed to maintain the gas temperature and prevent rainout by keeping the tube bore at a temperature higher than the dew point of the humidified gas.

[0177] [Table 5]

[0178] The flexibility of the pipes was tested using a three-point bending test. The pipes were placed in a three-point bending test jig and used with an Instron 5560 Test System instrument to measure the load and elongation. Each pipe sample was tested three times. The elongation of the pipes under the applied load was measured, and the average stiffness constant was obtained. The average stiffness constants for pipes A and B are shown in Table 6.

[0179] [Table 6]

[0180] As described above, the risk of rainout within the tube can be reduced by placing the heated wire 206 inside the inspiratory limb 202 and / or expiratory limb 210 to keep the tube wall temperature above the dew point temperature.

[0181] thermal properties In embodiments of the composite tube 1201 incorporating the heating filament 1215, heat may be lost through the walls of the first elongated member 1203, resulting in uneven heating. As described above, one way to compensate for these heat losses is to apply an external heating source at the walls of the first elongated member 1203, which helps to regulate the temperature and prevent heat loss. However, other methods can also be used to optimize the thermal properties.

[0182] Next, refer to Figures 19A to 19C. These figures show exemplary configurations for improving the cell height (i.e., the cross-sectional height of the first elongated member 1203, measured from the surface facing the lumen to the surface forming the maximum outer diameter) for improving thermal properties.

[0183] To reduce heat loss from the composite tube 1201, the dimensions of the cell can be selected. Generally, increasing the height of the cell also increases the effective thermal resistance of the tube 1201, because a greater cell height allows the first elongated member 1203 to hold more adiabatic air. However, it has been found that at a certain cell height, changes in air density cause convection inside the tube 1201, thereby increasing heat loss. Also, at a certain cell height, the surface area becomes large enough that the heat lost through the surface outweighs the benefits of a greater cell height. Specific embodiments include the realization of these.

[0184] The radius of curvature and curvature of a bubble can be useful in determining the desired bubble height. The curvature of an object is defined as the reciprocal of its radius of curvature. Therefore, the larger the radius of curvature of an object, the less curved it is. For example, a flat surface has an infinite radius of curvature and is therefore curvature of 0.

[0185] Figure 19A shows a longitudinal cross-section of the upper part of the composite pipe. Figure 19A shows one embodiment of the composite pipe 1201, in which the bubble body has a large height. In this example, the bubble body has a relatively small radius of curvature and therefore a large curvature. Also, the bubble body is about 3 to 4 times the height of the second elongated member 1205.

[0186] Figure 19B shows a longitudinal cross-section of the upper part of another composite tube. Figure 19B shows one embodiment of the composite tube 1201, in which the cell body is flattened at the top. In this example, the cell body has a very large radius of curvature and a small curvature. The cell body is also approximately the same height as the second elongated member 1205.

[0187] Figure 19C shows a longitudinal cross-section of the upper part of another composite tube. Figure 19C shows one embodiment of the composite tube 1201, in which the width of the bubble is greater than the height of the bubble. In this example, the bubble has a radius of curvature and curvature between that of Figure 19A and that of Figure 19B, and (compared to Figure 19A) the center of the radius with respect to the upper part of the bubble is outside the bubble. The inflection points on the left and right sides of the bubble are approximately in the center (in the height direction) of the bubble (whereas in Figure 19A they are at the bottom of the bubble). Also, the height of the bubble is approximately twice that of the second elongated member 1205, and the bubble height is between the height of Figure 19A and the height of Figure 19B.

[0188] The configuration in Figure 19A exhibited the minimum heat loss from the tube. The configuration in Figure 19B exhibited the maximum heat loss from the tube. The configuration in Figure 19C had heat loss intermediate between that of Figures 19A and 19B. However, the large outer surface area and convective heat transfer in the configuration in Figure 19A resulted in inefficient heating. Therefore, of the three bubble body configurations in Figures 19A to 19C, Figure 19C was judged to have the best overall thermal characteristics. When the same thermal energy was input to the three tubes, the configuration in Figure 19C produced the greatest temperature rise along the length of the tube. The bubble body in Figure 19C is large enough to increase the adiabatic air volume, but not large enough to cause significant heat loss due to convection. The configuration in Figure 19B was judged to have the worst thermal characteristics. That is, the configuration in Figure 19B produced only the smallest temperature rise along the length of the tube. The configuration in Figure 19A had intermediate thermal characteristics and produced a lower temperature rise than the configuration in Figure 19C.

[0189] While the configuration shown in Figure 19C may be preferred in certain embodiments, it should be understood that in other embodiments, other configurations, including those shown in Figure 19A, Figure 19B, and other variations, may also be used if desired.

[0190] Table 7 shows the height of the bubble body, the outer diameter of the tube, and the radius of curvature for the configurations shown in Figures 19A, 19B, and 19C, respectively.

[0191] [Table 7]

[0192] Next, refer to Figures 19C to 19F. These figures show exemplary positioning of the heating element 1215 in similar bubble body shapes to improve thermal properties. The position of the heating element 1215 can change the thermal properties inside the composite tube 1201.

[0193] Figure 19C shows a longitudinal section of the top of another composite tube. Figure 19C shows one embodiment of a composite tube 1201 in which the heating element 1215 is centrally located within a second elongated member 1205. This example shows heating elements 1215 that are close to each other but not close to the bubble wall.

[0194] Figure 19D shows a longitudinal cross-section of the top of another composite tube. Figure 19D shows one embodiment of a composite tube 1201 in which the heating element 1215 is located further away within the second elongated member 1205 than in Figure 19C. These heating elements are closer to the bubble wall, allowing for better temperature regulation inside the composite tube 1201.

[0195] Figure 19E shows a longitudinal cross-section of the upper part of another composite tube. Figure 19E shows one embodiment of a composite tube 1201 in which the heating element 1215 is positioned vertically separated from the second elongated member 1205 along its vertical axis. In this example, the heating element 1215 is similarly close to each bubble wall.

[0196] Figure 19F shows a longitudinal cross-section of the upper part of another composite tube. Figure 19F shows one embodiment of a composite tube 201 in which heating elements 1215 are spaced apart at both ends of a second elongated member 1205. In particular, compared to Figures 19C to 19E, the heating elements 1215 are closer to the bubble wall.

[0197] Of the four filament configurations shown in Figures 19C to 19F, Figure 19F was determined to have the best thermal characteristics. All configurations produced similar heat loss from the tube due to their similar bubble shapes. However, when the same thermal energy was input to the tube, the filament configuration in Figure 19F produced the largest temperature rise along the length of the tube. The configuration in Figure 19D was determined to have the second-best thermal characteristics, producing the second-largest temperature rise along the length of the tube. The configuration in Figure 19C produced the next-best results. The configuration in Figure 19E had the worst performance, producing only the smallest temperature rise along the length of the tube when the same amount of heat was input.

[0198] While the configuration shown in Figure 19F may be preferred in certain embodiments, it should be understood that in other embodiments, other configurations, including those shown in Figures 19C, 19D, and 19E, and other variations, may also be used if desired.

[0199] Next, we refer to Figures 20A to 20C, which show exemplary configurations relating to the lamination of the first elongated member 1203. In certain embodiments, it has been found that thermal dispersion can be improved by laminating multiple cellular bodies. These embodiments may be more beneficial when using the internal heating filament 1215. Figure 20A shows a longitudinal section of the top of another composite tube. Figure 20A shows a cross-section of a composite tube 1201 without lamination.

[0200] Figure 20B shows a longitudinal section of the top of another composite tube. Figure 20B shows another exemplary composite tube 1201 having stacked cells. In this example, two cells are stacked one above the other to form a first elongated member 1203. Compared to Figure 20A, the overall cell height remains the same, but the cell pitch is half that of Figure 20A. Also, the embodiment in Figure 20B has a slightly reduced air volume. The stacking of cells reduces natural convection and heat transfer in the gaps between the cells 1213, lowering the overall thermal resistance. The heat channels within the stacked cells are increased, allowing heat to dissipate more easily through the composite tube 1201.

[0201] Figure 20C shows a longitudinal section of the top of another composite tube. Figure 20C shows another example of a composite tube 1201 having stacked cell bodies. In this example, three cell bodies are stacked one above the other to form a first elongated member 1203. Compared to Figure 20A, the overall cell body height remains the same, but the cell body pitch is one-third of that in Figure 20A. Also, the embodiment in Figure 20B has a slightly reduced air volume. The stacking of cell bodies reduces natural convection and heat transfer in the gaps between the cell bodies 1213.

[0202] Additional exemplary intermediate connectors Figures 32A to 32C show another example of an intermediate connector 3200 comprising an intermediate PCB 3205 and an intermediate connection element 3210. The intermediate PCB 3205 may include conformal coverings configured to protect the intermediate PCB 3205 from water ingress. For example, water can follow the contour of the intermediate PCB 3205. The intermediate connector 3200 may include features configured to position a bead in a suitable location for mounting wires, such as heating or sensing elements of the circuits described herein. The intermediate PCB 3205 may extend partially through the intermediate connection element 3210. For example, a portion of the intermediate PCB 3205 may extend outside the tube of the intermediate connection element 3210, and a portion may extend partway through the lumen portion of the intermediate connection element 3210. In some configurations, the portion of the intermediate PCB 3205 extending into the lumen penetrates approximately one-third of the lumen. This provides relatively low flow resistance to the intermediate PCB that extends throughout the entire lumen.

[0203] In some embodiments, the intermediate PCB 3205 generates heat during operation, at least partially due to the diodes located within it. The heat generated by the intermediate PCB 3205 can help evaporate excess condensation.

[0204] The intermediate connector 3200 can be overmolded to securely fix the components in place and to seal the parts. In some embodiments, a clamshell can be applied to enhance the insulation of the intermediate connector 3200.

[0205] The intermediate connector 3200 may include a tube stopper 3220 configured to prevent the tube from rotating excessively, so that the tube stopper 3220 can be configured to trap the air bubble between the bead and the tube. The tube stopper 3220 may be configured to be positioned 180 degrees and / or 270 degrees from the PCB to ensure correct alignment of the tube. The tube stopper 3220 may be configured to provide a mounting point for the tube. The intermediate connector 3200 may include one or more bridges 3222 configured to lift the bead to allow the polymer to flow below the bead for the purpose of reducing water ingress. In some embodiments, one or more bridges 3222 may be located on each side of the intermediate connector 3200. The intermediate connector 3200 may include a comb-like section 3224 configured to hold a wire (e.g., a heater wire) in place within a slot. The intermediate connector 3200 may include an indicator, such as an arrow 3226, configured to indicate the orientation of the intermediate connector 3200 so that the diode is facing the correct direction. Arrow 3226 may also help reduce or prevent water ingress. The intermediate connector 3200 may include a watertight ring 3228 that forms a complete loop around the intermediate connector 3200. The watertight ring 3228 may be configured to restrict or eliminate water ingress into the exposed area of ​​PCB 3205.

[0206] In some embodiments, the intermediate connecting element 3210 may have a wall thickness of about 1 to 2 mm and a diameter of 4 to 15 mm. In some embodiments, the inner diameter of the intermediate connecting element 3210 may be about 8 to 9 mm and the outer diameter may be about 11.5 mm. The outer diameter of the intermediate connecting element 3210 can be made sufficiently large to reduce flow resistance. A smaller passage in the intermediate connecting element 3210 may mean that the gas passes through the passage faster, thereby reducing condensation.

[0207] The intermediate connector 3200 may include a process aid 3230 configured to correctly align the tube so that the bubble body engages with and is held in place in the tube. The intermediate connector 3200 may include a pin 3232 configured to position a cover (e.g., a clamshell 3300 as described herein with reference to Figure 33) and hold the cover by friction fit (e.g., a pin 3232 can engage with a mating recess in the cover). In some implementations, the intermediate connector 3200 includes three or four pins. The pin 3232 may be configured to be long enough to protrude through the overmolded portion for alignment and / or positioning purposes. The pin 3232 may be positioned on both sides of the intermediate connector 3200 so that it is positioned, for example, at a 90-degree angle from the illustrated position. In some embodiments, the intermediate connector 3200 includes a slot 3234 that acts as a machined keyway mechanism to reduce the possibility of incorrect orientation.

[0208] Figures 33A–33C show examples of clamshells 3300 applicable to intermediate connectors, such as the intermediate connector 3200 described herein with reference to Figure 32. The clamshell 3300 can be configured to provide an aesthetic cover for overmolded intermediate connectors, such as the intermediate connector 3200. The clamshell 3300 can also be configured to protect the PCB from damage.

[0209] The clamshell 3300 comprises two halves 3305a and 3305b that connect to each other. In some embodiments, the two halves 3305a and 3305b are permanently connected to each other (for example, separating the two halves would involve at least partially damaging or breaking the clamshell 3300, or in that case, a force of at least about 30 N would be required to separate the two halves 3305a and 3305b of the clamshell 3300). Each half 3305a and 3305b can be formed from the same one-piece tool and may be symmetrical so that one half can be rotated and fitted into the other half. The clamshell 3300 may include a snap-fit ​​connection comprising a clip 3309a and a clip receiving mechanism 3309b. The clip 3309a may be a pair of projecting clips extending diagonally opposite each other from the two covers of the clamshell 3300. Clip 3309a can be configured to interact with a complementary clip receiving mechanism 3309b to reduce the gap between halves 3305a and 3305b, keep the gap closed, and hold the ends in a closed position, thereby forming a primary coupling feature of the clamshell 3300. The clamshell 3300 may include a female positioning slot 3307a configured to engage with a male positioning pin 3307b. In some embodiments, the female positioning slot 3307a may include a slightly inward taper that requires force to insert the male positioning pin 3307b. The male positioning pin 3307b can be configured to be press-fitted into a corresponding female positioning slot 3307a in another half of the clamshell 3300. This can serve as a backup connection in case the snap-fit ​​connection fails.

[0210] The clamshell 3300 includes features such as ribs 3310a, 3310b to ensure that the clamshell is assembled correctly. Correct assembly may be at least partially due to two halves 3305a, 3305b that are configured so that they cannot fully engage with each other when the two halves 3305a, 3305b are assembled incorrectly. The cover 3300 may include a horizontal rib 3310b to reduce the vertical movement of the intermediate connector and a vertical rib 3310a to reduce the horizontal movement of the intermediate connector. The vertical rib 3310b may be configured to be longer so that the central rib is closer to the overmolded portion and rotation of the overmolded portion is reduced. The ribs 3310a, 3310b may generally be configured to receive and position pins from the overmolded intermediate connector. For example, ribs 3310a and 3310b may be configured to prevent or interfere with inaccurate positioning by pushing the pins of an overmolded intermediate connector (e.g., pin 3232 of intermediate connector 3200 as described herein with reference to Figure 32) off-center, and ribs 3310a and 3310b may also prevent or interfere with the engagement of a second pin.

[0211] The clamshell 3300 may include a bonding region 3315 comprising a protruding portion and a notched region. The bonding region 3315 may be configured to interact with a corresponding region in the other half of the clamshell 3300. The bonding region 3315 may be configured to prevent the formation of rough edges between the two halves 3305a, 3305b, resulting in a better overall finish, and may help guide the correct alignment of the halves. The bonding region 3315 may be configured to be symmetrical with a corresponding bonding region in the other half of the clamshell. The clamshell 3300 may include an internal notched region 3320 configured to allow space for an overmolded protruding PCB to fit into the region 3320.

[0212] In some embodiments, the overmolded intermediate connector 3200 can be configured to fit into the clamshell 3300 at at least four different positions. The intermediate connector 3200 may include, for example, three pins that are not centered relative to the intermediate connector 3200. In some embodiments, the intermediate pins may be centered relative to the other pins rather than to the intermediate connector 3200.

[0213] In some embodiments, the overmolded intermediate connector 3200 includes three or more pins 3220 for securely fastening the overmolded intermediate connector 3200 to the clamshell 3300. The pins 3220 can be configured to reduce horizontal and / or vertical translation and / or rotation about the horizontal axis, as described herein with reference to Figures 32A–32C. In some embodiments, four pins 3220 can be used to effectively position and place the overmolded intermediate connector 3200 within the clamshell 3300. In such embodiments, the two halves 3305a, 3305b of the clamshell 3300 may be asymmetrical. In addition, the fourth pin may push the wire outward, potentially increasing the possibility of wire exposure due to a reduced amount of overmolding material covering the wire. Pin 3220 may be configured long enough to engage with ribs 3310a and 3310b to reduce or prevent rotation of the overmolded intermediate connector 3200. In some embodiments, the center pin may be longer than the other pins. In addition, pin 3320 may be configured to be sufficiently thick for mechanical robustness.

[0214] The clamshell 3300 and the overmolded intermediate connector can comprise a component that reduces or prevents positional displacement of the overmolded intermediate connector within the clamshell 3300 during installation or manufacturing. In some embodiments, when the overmolded intermediate connector is inaccurately positioned within the clamshell 3300, the overmolded intermediate connector may move within the clamshell 3300, thereby preventing the two half portions 3305a and 3305b from being correctly coupled. This may cause the connection between the two half portions 3305a and 3305b to be released, leading the clamshell 3300 to detach from the overmolded intermediate connector.

[0215] The clamshell 3300 can be dimensioned based on the purpose of use. For example, the clamshell 3300 can be dimensioned according to the size of the opening in the side of an incubator. The clamshell 3300 can be configured to fit into the opening of the incubator and allow a tube to be positioned inside the incubator. However, if the clamshell 3300 is too small, the material strength may be reduced below an acceptable level. This may be particularly true with respect to a clipping mechanism. In some embodiments, the clamshell 3300 is configured to sit tightly without contacting the overmolded intermediate connector. As a result, it may be difficult to include additional structures or features in the clamshell 3300.

[0216] During manufacturing, the tube can be wrapped around either end of the intermediate connector before overmolding. The clamshell 3300 can be configured to sit close to the tube with little or no contact, since the tube may exert pressure on the clamshell 3300. The clamshell 3300 can be made from materials including polypropylene, acetyl, or other materials with similar properties.

[0217] In some embodiments, a cover (e.g., clamshell 3300) can include an integral hinge that can be used to connect the two halves of the cover. This integral hinge may provide a simple mechanism for assembling the cover. In some embodiments, an internal hinge can be integrated into the cover, and the hinge is combined with a clip to provide an effective coupling mechanism.

[0218] In some embodiments, the cover can include pins used to replace the horizontal and vertical ribs of the clamshell 3300. These pins can be configured to provide the same positioning function as ribs 3310a and 3310b of the clamshell 3300. In certain embodiments, the cover may use fewer pins or no pins at all. This cover may allow rotation of the intermediate connector, but may resist sliding of the intermediate connector. In some embodiments, the end of the positioning pin may be thickened such that the insertion portion forms a positioning point.

[0219] In some embodiments, the overmolded portion on the intermediate connector can form the outer cover. In some embodiments, the cover may be shaped to match the shape of the overmolded intermediate connector. In such configurations, the cover may be asymmetrical. The shape can be configured to reduce contact between the cover and the intermediate connector.

[0220] In some embodiments, the halves of the cover can be joined using ultraviolet (UV) curing glue, an adhesive, or using male and female positioning pins on the cover to form a press-fit connection.

[0221] Segmented heater control Figure 26 shows a flowchart of an exemplary method for controlling a segmented heater, such as one in an intake limb having a heater coupled to an extension limb also having a heater. The control method can be carried out by a humidification system or other control module as described herein. For ease of explanation, the following method is described as being carried out by a control module, but one or more steps of the method, or a single step portion of the method, can be carried out by any combination of components in the humidification system. In some embodiments, method 2600 can be executed at least once per second to provide substantially continuous and fine control of the humidification system.

[0222] In step 2605, the control module determines the power demand for the first heater section (e.g., a heater in the intake limb). This can be done, for example, using open-loop control. The default duty cycle can be determined to be the power demand for the first heater section, which is at least partially determined by the gas flow through the humidification system. In some embodiments, this default duty cycle can be used for the control of the first heater section and can be determined using a model configured to be applicable to the majority of situations. Advantageously, this can allow the control module to apply the same control parameters in most situations. For example, this can mean that the control module does not change its control parameters for different ambient conditions.

[0223] The power demand can be configured so that the control module maintains a target temperature profile, an example of which is shown in Figure 27. In some embodiments, the target temperature profile utilizes a greater amount of heating in the first heating section to reduce condensation (e.g., for a second heating section of the extension limb). For example, the first heating section can be controlled to heat the inspiratory limb beyond a setpoint to impart a lower relative humidity to the gas. This allows for effective control of gas cooling by the time the gas reaches the patient after flowing through the extension limb, enabling the gas to maintain a high absolute humidity.

[0224] In step 2610, the control module determines the temperature at the patient end of the combined inspiratory and extension limbs, which is determined using a patient end temperature sensor. The control module can be configured to monitor this temperature sensor frequently (e.g., once per second, twice per second, etc.). In response to the determined temperature, the control module can change the duty cycle to achieve a target temperature profile, a target absolute humidity or target relative humidity of the gas at the patient end, and / or a target temperature of the gas at the patient end.

[0225] In step 2615, the control module determines the difference between the setpoint temperature and the temperature measured at the patient end. For ease of reference, this difference is referred to as the error, but it is not assumed or understood that this value represents an error or other unintended result.

[0226] In step 2620, the control module determines the power demand for the combination of the first heater section and the second heater section (e.g., an intake limb and an extension limb connected to the intake limb). The power demand can be proportional to the length of the limb relative to the flow rate. For example, the control module can determine the power demand as power per unit length.

[0227] The power demand can be expressed as DC_12 = Kp*e + Ki*∫e dt, where DC_12 is the output of the control module for the first and second combinations (e.g., power, duty cycle, etc.), Kp is the proportionality constant in the proportional-integral-derivative (PID) control scheme, Ki is the integral coefficient in the PID scheme, and e is the error (i.e., the current difference between the setpoint temperature and the measured temperature, determined in step 2615). The control module can be configured to reduce or eliminate the error. For example, the control module can be configured to control the power supplied to each heater section to bring the current temperature to the setpoint, taking into account the short-term and long-term effects on temperature in response to the power supplied to each heater section.

[0228] In a PID control scheme, the value of Kp can be related to the rate of temperature change within the system. Kp can be changed to achieve a target or preferred rate of temperature change within the system, taking into account both short-term and long-term effects to reach the setpoint temperature. The product of Kp and e in the above equation can be called the proportional term in the PID scheme.

[0229] In a PID control scheme, the value of Ki can relate to the rate at which the system reaches the target setpoint as it approaches steady-state operation. The value of Ki can also relate to how quickly the system heats up. The integral of the error (e.g., ∫e de) represents the cumulative error over the time the system has been operating. The product of Ki and the cumulative error in the above equation can be called the integral term in a PID scheme.

[0230] In some embodiments, the PID control scheme does not contain a differential term.

[0231] In step 2625, the control module selectively heats the first and second heater sections to meet their respective power demands. In some embodiments, the power demand for the first heater section can be exceeded. In some implementations, the control module can implement an algorithm that allows the power demand for the first heater section to be exceeded depending on other control parameters, as described herein with reference to Figure 29.

[0232] The control module may be configured to take into account that the power demand for a first heater section is met if at least one of the following conditions is met: (1) the power demand for the first heater section is met by heating the first heater section; (2) the power demand for the first heater section is partially met by heating the first heater section and partially met by heating the second heater section, where the duty cycle of the combination of the first and second heater sections contributes to the total demand and any deficit is met by heating the first heater section (see Figure 28 for an example of this); or (3) the demand for the first heater section is met by heating the combination of the first and second heater sections.

[0233] Figure 28 shows a functional block diagram 2800 illustrating the relationship between the processing components of the control module, the demand associated with the heater section, and the application of the resulting duty cycle determination. For example, the control module may implement a PID control device 2802 as described herein with reference to Figures 26 and / or 30. The PID control device 2802 may be configured to control a combination of first and second heater sections 2806 (e.g., the outer loop of the intake limb coupled to the extension of the intake limb) based at least in part on the demand determined by the control module, as described herein with reference to Figure 26. The control module may implement a control algorithm 2804 as described herein with reference to Figures 26, 29, and / or 31. The control algorithm 2804 can be used to control a first heater section 2808 based at least in part on the demand determined by the control module. The control module can apply power to the first and second heater sections 2806 based on a duty cycle 2810 determined to satisfy the demands of the first and second heater sections 2806 using the PID control device 2802. Similarly, the control module can apply power to the first heater section 2808 based on a duty cycle 2812 determined to satisfy the demands of the first heater section 2808 using the control algorithm 2804. In some embodiments, the control algorithm can determine the duty cycle 2812 for the first heater section based at least in part on the demands for the combination of the first and second heater sections, since the power applied to the combination of heater sections affects the temperature and humidity of the gas in the first section. For example, as described herein with reference to Figure 26, the demands of the first heater section can be partially or completely satisfied by the demands for the combination of the first and second heater sections.In certain embodiments, the PID control device 2802 may be configured to be the primary means for controlling the heating of the combined intake and extension limbs (e.g., the first and second heater sections), and the control algorithm 2804 for the intake limbs (e.g., the first heater section) may act as a method for providing auxiliary heating, which may be particularly suitable during certain operating stages (e.g., startup, warm-up period, temperature change period, etc.).

[0234] Figure 29 shows a flowchart of an exemplary control algorithm 2900 implemented by a control module to control a segmented heater. In step 2902, the control module operates in open-loop control mode by setting the power demand for the first heater segment to a fixed duty cycle value. In some implementations, the fixed duty cycle value can be initially set to 80%. The duty cycle value can be increased or decreased as determined by the steps of the control algorithm.

[0235] In step 2904, the control module determines whether the humidification system is in standby mode. In some embodiments, the control module can determine if the humidification system is in standby mode by examining the values ​​stored in local variables. If the humidification system is in standby mode, the control module proceeds to step 2906 to determine whether the patient end temperature (Tpe) has increased by more than a change threshold Tth (e.g., about 2°C) within a time frame (e.g., about 1 minute). This allows for an effective determination of whether flow has been added to the humidification system. If flow has been added as determined in step 2906, the control module exits standby mode in step 2908.

[0236] When the unit is not in standby mode as determined in step 2904, or after exiting step 2908, the control module determines in step 2910 whether the heater plate temperature exceeds the heater plate temperature threshold Tth_hp (e.g., about 50°C). This may correspond to a warm-up period. If the control unit determines that the heater plate temperature exceeds the heater plate temperature threshold, the control module determines in 2912 whether the duty cycle DC_12 of the combination of the first and second heater sections (e.g., the outer section) is greater than about 99%, and whether the patient end temperature Tpe is less than the setpoint temperature minus the temperature value Tnear (configured to determine the point in time when the patient end temperature approaches the setpoint temperature). In some embodiments, the value of Tnear may be about 2°C. If the control module determines that the combination of the first and second heater sections is greater than approximately 99% and the patient end temperature is less than the setpoint temperature minus Tnear, then a no-flow condition may exist within the humidification system. For example, a no-flow condition may exist if the humidification system is applying a duty cycle of approximately 100%, but the patient end temperature is not close enough to the setpoint. If this is true, the control module proceeds to step 2914 to take into account potential disturbances in the system (such as placing a cold object on top of the system) and waits for an adjusted time t_wait (e.g., approximately 5 minutes). If it is longer than time t_wait, the control module proceeds to step 2916 and enters a standby state until flow is applied or reapplied to the humidification system. In the standby state, the control mode sets the duty cycle of the first heater section to 0% and the combination of the first and second heater sections to approximately 40%.

[0237] If the result of the determination in step 2910, 2912, or 2914 is "no", the control module proceeds to step 2918 to control the combination of the first and second heater sections using a PID control scheme to achieve a target setpoint for the patient end. In some embodiments, the PID control scheme is the method described herein with reference to Figure 30. For example, the control module may control the combined first and second heater sections to achieve a target setpoint based on the difference between the current measured temperature at the patient end and the setpoint. In certain embodiments, the control is proportional to the difference between the measured temperature and the temperature setpoint. In step 2920, the control module may monitor a timer to determine when an adjusted time threshold (e.g., 30 seconds) has elapsed. This adjusted time threshold can be set to allow sufficient time to elapse for the PID control device to become active. The control module implements the PID control scheme to achieve a duty cycle that results in satisfying the relevant demand, the demand determined in step 2922. For example, a PID control scheme can be implemented to achieve a duty cycle DC_12 for a combination of first and second heater sections and / or a duty cycle DC_1 for the first heater section, where the duty cycle for the first heater section takes into account the demands of the combination of the first and second heater sections.

[0238] After the adjusted time threshold has elapsed, the control module proceeds to step 2924 to determine whether (a) the duty cycle for the combined first and second heater sections is equal to 0%, (b) the patient end temperature exceeds the setpoint (e.g., about 39°C), or (c) the duty cycle for the first heater section is greater than the duty cycle threshold (e.g., about 40%). This test may be true if the combined first and second heater sections have stopped heating the gas, and therefore it is appropriate to reduce the temperature profile of the inspiratory limb. This can be achieved, for example, by reducing the duty cycle of the first heater section. Therefore, if this is true, the computer module reduces the duty cycle for the heater cycle by a reduction value (e.g., 2%) in step 2926. If the test is not true, the control module proceeds to step 2928 to determine whether (a) the duty cycle for the combined first and second heater sections is greater than the duty cycle for the first heater section plus a constant c (e.g., whether DC_12 > DC_1 + c (where c may be approximately 20%)) and (b) whether the duty cycle for the first heater section is less than the inner interval threshold DC_1th (e.g., approximately 80%). The constant can be adjusted so that the initial duty cycle value plus the constant is 100% (e.g., the initial duty cycle value may be 80% so that the constant may be 20%). This test may be true if it may be preferable to increase the duty cycle of the first heater section to maintain the temperature profile of the intake limbs. Therefore, if this test is true, the control module proceeds to step 2930 to increase the duty cycle of the first heater section by an incremental value (e.g., approximately 2%). If the test is not true, the control module returns to step 2922 described above. If the control module increases or decreases the duty cycle of the first heater section, the control module resets the timer in step 2932. The control can then return to step 2922.

[0239] FIG. 30 is a flowchart of an exemplary PID control scheme 3000 configured to perform closed-loop control to achieve a target temperature setpoint at the patient end using combined first and second heater sections. The PID control scheme can be used to determine a duty cycle for the combined first and second heater sections.

[0240] In step 3002, the control module initializes PID parameters by determining a difference between the measured temperature Tpe and the temperature setpoint Tset, the difference is referred to as error e: e=Tset-Tpe. In step 3004, the control module sets a proportional term P of the PID control scheme as the product of a constant Kp and the error e: P=Kp*e. In certain implementations, the constant Kp is set to about 10. In step 3006, the control module sets a derivative term D of the PID control scheme to 0. Other values may also be used.

[0241] In step 3008, the control module determines whether the error is less than or equal to a temperature difference threshold Tdiff (e.g., about 100). The control module can be used to determine when it is appropriate to set an integral term I of the PID control scheme to 0, as shown in step 3010. If the current temperature is within the temperature difference threshold of the temperature setpoint, the control module proceeds to step 3011, where the integral term I of the PID control scheme can be taken as an old or previous integral term plus a proportional Ki of the error e: I=Iprev+Ki*e. In certain implementations, the proportional Ki may be about 0.05. The control module may further check in step 3012 that the integral term I is within an acceptable or suitable boundary (e.g., -2<I<100), and the control module may set the integral term to a boundary value if the integral term is outside the suitable range.

[0242] In step 3014, the control module determines the duty cycle as the sum of the proportional term P, the integral term I, and the differential term D: DC = P + I + D. If, as determined by the control module in step 3015, the duty cycle is greater than 100% and the integral term is greater than the previous integral term (e.g., I > Iprev), the control module resets the integral term to its previous value in step 3016 and recalculates the duty cycle in step 3018. In step 3020, the control module limits the range of the duty cycle value to 0 to 100 (e.g., if the duty cycle is less than 0, the control module sets the duty cycle to 0; if the duty cycle is greater than 100, the control module sets the duty cycle to 100).

[0243] Figure 31 shows a flowchart of another exemplary control algorithm 3100 that can be implemented by a control module in a humidification system. In step 3102, the control module determines the flow rate range of the humidification system. In step 3104, the control module determines the demand for the first heater section based on the determined flow rate range. In some embodiments, the flow rate range may be the flow rate level for the corresponding demand. For example, the flow rate range may be a low flow rate range, a medium flow rate range, or a high flow rate range, and a low flow rate demand can be determined for the low flow rate range, a medium flow rate demand can be determined for the medium flow rate range, and a high flow rate range can be determined for the high flow rate range. In some embodiments, the flow rate ranges may overlap. In certain embodiments, the control module determines the flow rate range only to determine the initial demand for the first heater section at startup. In such cases, the control module can use the demand for the combination of the first and second heater sections for controlling most of the humidification system. After this initial setup, the rest of the control algorithm 3100 can adjust the demand for the first heater section.

[0244] In step 3106, the control module determines whether the humidification system is in standby mode. For example, the control module can determine if the humidification system is in standby mode by checking the value stored in the local variable. If the humidification system is in standby mode, the control module proceeds to step 3108 to determine whether the patient end temperature (Tpe) has risen by more than 2°C in approximately one minute. This effectively determines whether flow has been added to the humidification system. If flow has been added as determined in step 3108, the control module exits standby mode in step 3110.

[0245] If the unit is not in standby mode as determined in step 3106, the control module determines in step 3112 whether the heater plate temperature is above approximately 50°C. This may correspond to a warm-up period. If the control unit determines that the heater plate temperature is above approximately 50°C, the control module determines in step 3114 whether the duty cycle of the combination of the first and second heater sections (e.g., the outer section) is greater than approximately 99%, and whether the patient end temperature Tpe is below the setpoint temperature minus the temperature value Tnear (e.g., approximately 2°C). If the control module determines this is true, there may be a no-flow condition in the humidification system. For example, a no-flow condition may exist if the humidification system is applying a duty cycle of approximately 100%, but the patient end temperature is not close enough to the setpoint. If this is true, the control module proceeds to step 3116 to take into account potential disturbances in the system (such as placing a cold object on top of the system) and waits for approximately 5 minutes. If the time is longer than approximately 5 minutes, the control module proceeds to step 3118 and enters a standby state until the flow is applied to or reapplied to the humidification system. In the standby state, the control mode sets the duty cycle of the first heater section to 0% and the combined duty cycle of the first and second heater sections to approximately 40%.

[0246] If the result of the determination in step 3112, 3114, or 3116 is "no", the control module proceeds to step 3120, where it controls the combination of the first and second heater sections using a PID control scheme to achieve a target setpoint for the patient end. In some embodiments, the PID control scheme is the method described herein with reference to Figure 30. For example, the control module can control the combined first and second heater sections to achieve a target setpoint based on the difference between the current measured temperature and the setpoint at the patient end. In certain embodiments, the control force is proportional to the difference between the measured temperature and the temperature setpoint. The control module implements the PID control scheme to achieve a duty cycle that results in satisfying the relevant demand, the demand determined in step 3122. For example, a PID control scheme can be implemented to achieve a duty cycle DC_12 for the combination of the first and second heater sections and / or a duty cycle DC_1 for the first heater section, where the duty cycle for the first heater section takes into account the demands of the combination of the first and second heater sections.

[0247] The control module proceeds to step 3124 to determine whether (a) the duty cycle for the combined first and second heater sections is equal to 0%, (b) the patient end temperature exceeds the setpoint (e.g., about 39°C), or (c) the duty cycle for the first heater section is greater than the duty cycle threshold (e.g., about 40%). This test may be true if the combined first and second heater sections have stopped heating the gas, and therefore it is appropriate to reduce the temperature profile of the inspiratory limb. This can be achieved, for example, by reducing the duty cycle of the first heater section. Therefore, if this is true, the computer module, in step 3126, reduces the duty cycle for the heater cycle by a reduction value (e.g., 2%) every 30 seconds while this is true. If the test is not true, the control module proceeds to step 3128 to determine whether (a) the duty cycle for the combined first and second heater sections is greater than the duty cycle for the first heater section plus a constant (e.g., DC_12 > DC_1 + c, where the constant may be approximately 20%) and (b) the duty cycle for the first heater section is less than the inner interval threshold (e.g., approximately 80%). The constant can be adjusted so that the initial duty cycle value plus the constant is 100% (e.g., the initial duty cycle value may be 80% so that the constant may be 20%). This test may be true if it may be preferable to increase the duty cycle of the first heater section to maintain the temperature profile of the intake limbs. Therefore, if this test is true, the control module proceeds to step 3130 to increase the duty cycle of the first heater section by an incremental value (e.g., approximately 2%). If the test is not true, the control module may return to step 3122 or step 3106 as described above. If the control module increases or decreases the duty cycle of the first heater section, the control module may return to step 3122 or step 3106.

[0248] Additional control systems Next, we describe another exemplary control system for circuit diagram 2500 shown in Figures 25A to 25C. As described above, circuit diagram 2500 can be implemented in a system that does not include a temperature sensor in the intermediate connector connecting a first heater section H1 in the intake limb to a second heater section H2 in the extension limb. Circuit diagram 2500 can be implemented using a control system configured to change the switching of a MOSFET pair to heat either the inner loop HW1 or the outer loop HW2. Loop HW1 (shown in Figure 25C) may contain the first heater section H1 of the intake limb. Loop HW2 (shown in Figure 25B) may contain the first and second heater sections H1 and H2. Depending on the polarity of the voltage, power can be supplied to loop HW1 to heat H1 or to loop HW2 to heat both H1 and H2. In this application, power can include power, voltage and / or current. Loop HW1 can be operated by switching a MOSFET on / off in a switching configuration, as shown in Figure 25C. The diode / switch can be a MOSFET. The polarity of the power supply can be switched to operate only loop HW2, as shown in Figure 25B. The control unit can be configured to operate the MOSFETs to switch polarity as needed to provide the appropriate duty cycle for the heater wire.

[0249] Figure 35 shows an exemplary control algorithm 3500 for controlling loops HW1 and HW2. In the exemplary embodiment, loops HW1 and HW2 can be controlled sequentially, thereby enabling smooth execution of algorithm 3500. The control device can repeat all steps to determine whether and at what level the output of the HW1 or HW2 duty cycle needs to be controlled. In step 3502, the control device can determine the error between the patient end temperature measured by a patient end sensor, such as sensor 204b shown in Figure 13, and the patient end setpoint. The outputs of the HW1 and HW2 duty cycles can each be controlled using a PID control device known in the art based on the error. In step 3510, the control device can optionally perform one or more initial system readiness checks. If the system is not ready, a system reset 3505 can be performed. If the system is ready, in step 3515, the output of the HW1 duty cycle can be determined based on the error between the measured patient end temperature and the patient end temperature setpoint. The output of the HW1 duty cycle can optionally be based on a standard PID control device using a set of constants. In some embodiments, the PID control device can implement the PID control scheme 3700 shown in Figure 37, which will be described in more detail below. The control device can determine the output of each term (i.e., proportional, integral, and derivative terms) based on the error and a set of constants. The constants can be predetermined for the system and stored in memory, a lookup table, or any other preferred format. The constants can be modified in response to changes in conditions, as the system can store multiple constants that may be relevant to a number of environments. A non-limiting example is when part of the conduit is inside or outside the incubator.

[0250] In one embodiment, the entire inspiratory duct, including the inspiratory limb and the extension limb, is exposed to the same ambient environment along its length. In this embodiment, the control device can function as a standard PID control device that controls the output of the HW2 duty cycle in step 3515. Since there may be a large error between the measured patient end temperature and the patient end temperature setpoint, the loop HW2 can be heated using a set of constants. The error may be large because the patient end of the inspiratory duct is exposed to ambient temperatures that may be much lower than the patient end temperature setpoint. In this embodiment, algorithm 3500 can output a large HW2 duty cycle in step 3520. The control device can then determine the output of the HW1 duty cycle in step 3625. In this embodiment, since the output of the HW1 duty cycle may be inversely correlated with the output of the HW2 duty cycle, the HW1 duty cycle can be set to 0%. If the output of the HW2 duty cycle is sufficiently high, the output of the HW1 duty cycle can be set to 0%. This may occur if there is a large error value between the patient end temperature and the patient end setpoint.

[0251] The power supplied to loop HW2 raises the temperature of heater wires H1 and H2, allowing the error to be reduced to an appropriate error threshold. As described above, the control device can continuously execute algorithm 3500 so that the error is continuously monitored. In this embodiment, when the error is within an appropriate error threshold, loop HW1 may be activated to achieve temperature control. Further details of the activated loop HW1 are described below with reference to another embodiment.

[0252] In some embodiments, the inspiratory limb and extension limb can be exposed to different ambient environments. For example, the extension limb can be placed in a controlled environment, such as an incubator or other suitable device, which is a closed system. The controlled environment can control at least the temperature and / or humidity within the environment. When the extension limb is inserted into the incubator, the patient end sensor can read a higher temperature value closer to the setpoint due to the temperature inside the incubator, which is higher than the ambient temperature. Therefore, the error may be smaller than when the extension limb is exposed to ambient temperature. Loop HW1 can be activated when the error is within a predetermined threshold, which is typically the case when the extension limb is placed inside the incubator. In non-limiting examples, the threshold error value may be 2.5°C or less. The control device can determine the output of the HW1 duty cycle in step 3525. In some embodiments, the control device can perform PID control 3700 of the output of the HW1 duty cycle, as shown in Figure 37. As the error is further reduced by heating H1, the output of the HW2 duty cycle determined in step 3515 is further reduced, so the output of the HW1 duty cycle can be further increased.

[0253] Continuing with the embodiment of the incubator, the control device is configured to control the power supplied to loop HW1 so that H1 is energized to its maximum capacity until H1 reaches a predetermined surface temperature threshold. The surface temperature threshold can prevent the intake limbs from becoming too hot to safely handle or use the humidification system. In some embodiments, the surface temperature threshold may be mandated by regulatory standards. The predetermined surface temperature threshold may be related to the maximum power / voltage supplied to loop HW1. The maximum power / voltage can be set based on experimental data.

[0254] Furthermore, when the control unit supplies power to loop HW1 in step 3530, H2 is not energized, and therefore H2 does not heat up, which can cause a temperature drop along the entire extension limb from the intermediate connector to the patient end. This temperature drop may be a temperature drop at a known rate of decay due to the well-known cooling characteristics within the incubator. The power supplied to loop HW1 can be controlled to achieve the initial temperature of the extension limb so that the temperature drop along the entire extension limb can result in a desired patient end temperature. Figure 27 shows an exemplary heating profile of the inspiratory line in this embodiment of the incubator. At the end where the inspiratory line connects to the humidification chamber, the temperature may be higher or lower than the patient end temperature, depending on the chamber outlet temperature setpoint. The control unit can determine the difference between the chamber outlet temperature and the measured patient end temperature, and thus adjust the output of the HW1 duty cycle. The temperature of the inspiratory limb can rise along the length of the inspiratory limb, which may terminate at the intermediate connector, and can gradually decrease along the extension limb from the intermediate connector to the patient end, which is not heated when loop HW1 is activated.

[0255] In control algorithm 3500, loop HW1 can perform most of the heating of the humidification system. Loop HW2 can take over if the error exceeds a threshold. In addition, the control device can keep the output of the HW2 duty cycle at a low value. On the one hand, the low output of the HW2 duty cycle can advantageously reduce the possibility of overheating of the extension limbs inside the incubator, thereby increasing the safety of the humidification system. For example, the low output of the HW2 duty cycle can prevent burns to infants in the incubator or caregivers handling the inspiratory tube. At the same time, H1 can heat up to the surface temperature threshold to advantageously prevent condensation inside the inspiratory limbs. On the other hand, the low output of the HW2 duty cycle can advantageously allow loop HW2 to respond quickly to environmental changes and maintain the heating profile as shown in Figure 27. Rapid environmental changes include, but are not limited to, temperature changes inside the incubator, ventilation, and low ambient temperatures. Furthermore, by supplying power to loop HW2, a more stable heating profile can be provided, which is even more advantageous. A more stable heating profile can be achieved by reducing or eliminating vibrations when loop HW2 is activated. Vibrations may occur when only loop HW1 is activated because it takes time for heat to be transferred by the heated gas moving from the inspiratory limb to the patient end and detected by the patient end sensor. When both heater sections H1 and H2 are activated, the patient end sensor can detect a faster temperature change response at the patient end than when only loop HW1 is activated, thus reducing vibrations.

[0256] Since the PID control scheme is configured to reduce errors, in some embodiments the output of the HW2 duty cycle can reach a steady state at 0%, and loop HW2 is operated to respond only to rapid changes in the environment as described above. The steady state may result from the proportional and derivative terms for loop HW2 being reduced to substantially zero when the error is within a threshold. In other embodiments, the output of the HW2 duty cycle may have a low value but not achieve a steady state. As an example, but not limited to, when the inspiratory tubing is in low ambient conditions, the cooling of the gas in the inspiratory limb outside the incubator may be increased. Rapid cooling may result from a lower ambient temperature, which may cause a higher rate of heat dissipation from the heated and humidified gas in the tubing to the ambient environment. In 3530, the power supplied to both H1 and H2 in the operated loop HW2 can compensate for the increased cooling of the gas in the inspiratory limb to achieve the desired patient end temperature.

[0257] Figure 36 shows another exemplary control algorithm 3600 for controlling the outputs of the HW1 and HW2 duty cycles. Control algorithm 3600 can have the same features as control algorithm 3500, except as described below. Thus, the features of control algorithm 3600 can be incorporated into the features of control algorithm 3500, and the features of control algorithm 3500 can be incorporated into the features of control algorithm 3600.

[0258] The control unit can continuously execute algorithm 3600. Continuous execution of algorithm 3600 can provide substantially continuous fine control of the humidification system. The control unit can initiate 3602 by determining the error between the measured patient end temperature and the patient end setpoint. In some embodiments, the patient end setpoint may be independent of the gas flow rate in the inspiratory line. The setpoint may be a function of the chamber outlet temperature setpoint. For example, the patient end temperature setpoint may be set higher or lower than the chamber outlet temperature setpoint. The patient end setpoint may be changed if the humidification system is in a very cold ambient environment. Furthermore, continuous execution of algorithm 3600 can allow the system to be reset (3605) whenever significant overheating occurs. In exemplary embodiments, reset 3605 may reset the error term used in the PID control algorithm to 0 and reset the outputs of both the HW1 and HW2 duty cycles to 0%.

[0259] As shown in Figure 36, the control unit can initiate algorithm 3600 with a series of checks 3610, 3615, 3620, and 3625 to ensure that all sensors are activated, all alarms are activated, and the system is operational. These checks may be optional. Specifically, the control unit can check whether a reset needs to be performed (3610). In some embodiments, the control unit can be programmed to determine whether a reset needs to be performed based on a predetermined algorithm. In other embodiments, the system may have a user interface to allow a user or caregiver to manually reset the system. For example, a reset can be performed by turning the device on or off using an on / off button, by unplugging the device, or automatically by software when the necessary conditions are met. If a reset is not needed in step 3610, the control unit can determine whether the system is ready to execute algorithm 3600 in step 3615. If the system is not ready, a reset 3605 can be performed. If the system is ready, the control unit can determine the state of the patient end sensor and the sensor at the outlet of the humidification chamber (3620). The system can be reset 3605 if the sensor is unresponsive or not functioning as designed. If the sensor status meets the requirements, the control unit can determine in step 3625 whether high temperature control or high temperature alarm is enabled. Reset 3605 can be activated to prevent overheating of the intake duct if the measured temperature is higher than the overheating temperature threshold. In some embodiments, if the patient end temperature exceeds the overheating temperature threshold, a separate software module configured to control overheating can take over. This overheating module can set the outputs of both the HW1 and HW2 duty cycles to 0. Reset 3605 can be performed to prevent the accumulation of integral error terms in PID control schemes 3630, 3680.

[0260] Continuing to refer to Figure 36, after determining that the patient end temperature is below the setpoint and after a series of optional checks, the control device can determine the output of the HW2 duty cycle to bring the system to the desired setpoint temperature. The control device can implement a PID control scheme for the output of the HW2 duty cycle in step 3630. In exemplary embodiments, the PID control step 3630 can be carried out using a PID control scheme known in the art. Generally, the output of the control device for HW1 or HW2 in a PID control scheme can be expressed by the equation DC = Kp*e + Ki*∫e dt + Kd*de / dt, where DC is the output of the HW1 or HW2 duty cycle, Kp is the proportionality constant, Ki is the integral constant, and Kd is the derivative constant. Furthermore, e is the error determined in step 3602. In addition, ∫e de is the error integral; that is, the integral of the past error from time 0 to the current time t.de / dt is the rate of change of the current error (i.e., the derivative term). PID control schemes can be configured to reduce or eliminate errors.

[0261] Figure 37 shows an example of a PID control scheme 3700. The PID coefficients 3705, PID limits 3710, and error term 3715 can be input to the PID control scheme 3700. As described above, the PID coefficients 3705 may include a proportionality coefficient Kp, an integral coefficient Ki, a derivative coefficient Kd, and an error when introducing the integral term. In some embodiments, the proportionality coefficient may be a system-based term determined by test. In some embodiments, the derivative coefficient Kd can be determined for the system and / or the heater plates (not shown) of loops HW1 and HW2. For example, Kd can be determined experimentally. A PID control scheme 3700 including the derivative coefficient Kd can increase system stability and reduce overshoot when correcting errors. In some embodiments, a PI control scheme can be used instead of the PID control scheme 3700, excluding the derivative term. The output of the control device in a PI control scheme can be expressed as DC = Kp*e + Ki*∫e dt. The PID limit 3710 may include minimum and maximum integral terms, as well as minimum and maximum power limits for the HW1 and HW2 duty cycles. The error term 3715 may include the current error, the error integral, and the previous error.

[0262] From the input described above, the control unit can calculate the proportional term 3720, which is the product of the proportionality constant Kp in the above equation and the current error of the system. The control unit can also calculate the differential term 3725, which is the product of the derivative constant Kd in the above equation and the rate of change of the current error de / dt. The control unit can calculate the error integral in step 3735. Then, the control unit can verify the error term in step 3740. For example, the control unit can verify the error term for any PID variable.

[0263] After error term verification 3740, the output of the control device can be calculated in step 3780 as DC = proportional term + Ki * error integral + derivative term. In step 3795, the control device can limit the range of the output value calculated from step 3780 to the maximum output limit of the control device ~ minimum output limit. The control device can provide the resulting output 3795 to step 3630 or step 3680 in Figure 37, as described below.

[0264] Returning to Figure 36, the control unit can output a limited HW2 duty cycle in step 3635, ranging from 0% to 100%, based on the PID control in step 3630. Algorithm 3600 can use the output of the HW2 duty cycle to control the patient end temperature and maintain the heating profile shown in Figure 27. As mentioned above, the HW2 output may be low, improving patient and caregiver safety by preventing overheating of the extended limb, while also allowing the loop HW2 to respond quickly to rapid changes.

[0265] Algorithm 3600 can also use the output of the HW2 duty cycle to control the output of the HW1 duty cycle. Before providing the output of the HW2 duty cycle to step 3640 to calculate the PID limits of the output of the HW1 duty cycle, the control unit can filter the raw output of the HW2 duty cycle in step 3645. Filtering can attenuate the output of the HW1 duty cycle. The filter can allow smoothing of noise from the heated loop HW2, thereby allowing attenuation of the output of the HW1 duty cycle. As shown in Figure 36, the control unit can sequentially control the outputs of the HW2 and HW1 duty cycles, thereby advantageously allowing for easy allocation of available power, voltage, or current. The PID control of the output of the HW2 duty cycle in step 3630 and the PID control of the output of the HW1 duty cycle in step 3680 can work together to provide more stable control of the system. If the output of the HW1 duty cycle causes the patient end temperature to become excessively hot or cold, the output of the HW2 duty cycle can compensate for the overheating or underheating. In some embodiments, the output of the HW2 duty cycle may be negative to result in a rapid change in the integral term of the PID control algorithm. If the output of the HW2 duty cycle is negative in step 3630, the control device may limit the output of the HW2 duty cycle to 0 in step 3635. The control device may also rapidly reduce the output of the HW1 duty cycle under overheating conditions.

[0266] Continuing to refer to Figure 36, the control device can determine the PID limits for the output of the HW1 duty cycle in step 3640. Specifically, the control device can calculate the maximum output of the HW1 duty cycle in step 3650. As mentioned above, the maximum output of the HW1 duty cycle can also be capped to prevent the intake limb from exceeding a surface temperature threshold and becoming unsafe to handle or use. In some embodiments, the maximum output of the HW1 duty cycle can be calculated using a function that includes the maximum upper limit output of the HW1 duty cycle and the range-limited output of the HW2 duty cycle. In one embodiment, the determination of the output of the HW1 duty cycle may also include a term to compensate for the difference in resistance between the two heater sections H1 and H2.

[0267] Next, the control device can determine whether the maximum output of the HW1 duty cycle calculated in step 3650 is negative. If the calculated maximum output of the HW1 duty cycle is negative, the control device can set the maximum output of the HW1 duty cycle to 0% in step 3660. If the calculated maximum output of the HW1 duty cycle is not negative, the control device can limit the output range of the HW1 duty cycle to 0% (or more) to the maximum output limit of the HW1 duty cycle (or less) in step 3675. In some embodiments, the maximum output limit of the HW1 duty cycle can be calculated by subtracting the output of the HW2 duty cycle from 100%.

[0268] Based on the PID limits calculated in step 3640, the control unit can perform PID control of the HW1 duty cycle output in step 3680. The control unit can output the HW1 duty cycle in step 3685. In one embodiment, the control unit can use the PID control scheme shown in Figure 37 to perform PID control of the HW1 duty cycle output. The control unit can also reset the system after PID control of the HW1 duty cycle output in step 3680 (3605).

[0269] Figure 38 shows another exemplary embodiment of the intake line 3802, which can be controlled using algorithms 3500 and 3600. The intake line 3802 in Figure 35 may have the same features as the intake line 202 in Figure 1, except as described below. Features of the intake line 3802 can be incorporated into the features of the intake line 202, and features of the intake line 202 can be incorporated into the intake line 3802 in Figure 38.

[0270] As shown in Figure 38, the intake line 3802 can be used together with the incubator 3808, or with another system where different temperatures exist along different sections of the intake limb 3802, such as a radiant heater, as illustrated. The intake line 3802 may comprise two sections. The first section or intake limb 3802a may be outside the incubator 3808, and the second section or extension limb 3802b may be inside the incubator 3808. The first section 3802a may include one or more first internal heater wires 3806a, and the second section 3802b may include one or more second internal heater wires 3806b. The first and second internal heater wires 3806a, 3806b may have the same characteristics as the first and second heater wires 206a, 206b in Figure 2. The intake line 3802 may have a gas lumen 3803. The first and second internal heater wires 3806a and 3806b can be wrapped around the gas tube lumen 3802.

[0271] Continuing to refer to Figure 38, the intake limb 3802 may include an intermediate connector 3814 having an intermediate circuit configured to connect elements of the first and second sections 3802a, 3802b of the intake line 3802. In some embodiments, the intermediate connector 3814 may be configured to physically and electrically connect the first inner heater wire 3806a to the second inner heater wire 3806b. In addition, the intake line 3802 may include one or more outer heater wires 3807. The outer heater wires 3807 may have the same or different characteristics as the first and second inner heater wires 3806a, 3806b. In some embodiments, the outer heater wires 3807 may be wrapped around the intake line 3802. In some embodiments, the outer heater wires 3807 may be located outside the gas lumen 3803. In exemplary embodiments, the outer heater wires 3807 may be in a helical configuration. However, those skilled in the art will understand that the number or configuration of the outer heater wires 3807 is not limiting.

[0272] The control device (shown in Figure 9) can be configured to control the first inner heater wire 3806a that forms the inner control loop (loop HW1). The control device can also be configured to control the outer heater wire 3807 that forms the outer control loop (loop HW2). Figures 25A to 25C show circuit diagrams 2500 relating to the intake line 3802, where H1 corresponds to the first inner heater wire 3806a and H2 corresponds to the outer heater wire 3807.

[0273] The inspiratory limb 3802 may include one or more sensors, and the control unit may be configured to receive the outputs of one or more sensors. As shown in Figure 38, sensor 3804b may be positioned near the patient end of the second section 3802b so that the parameter derived from sensor 3804b (patient end temperature) may correspond to the parameter of the humidifying gas delivered to the patient or user. In some embodiments, sensor 3804b may function in the same way as sensors 204a, 204b described above. The output of sensor 3804b may be transmitted to the control unit as feedback used to control the power, voltage, and / or current supplied to the HW2 and HW1 loops.

[0274] Additional control system for low flow conditions As described herein, the humidification system incorporating the circuit diagram 2500 in Figures 25A–25C can be used with an incubator. A non-limiting exemplary use with an incubator may be when the humidification system is operating in neonatal treatment mode and connected to an infant patient inside the incubator. Figure 39A shows an exemplary intended configuration of the humidification system's intake line 3902 and the incubator 3908. The intake leg 3902a, with heater wire section H1 3906a, can remain outside the incubator 3908 and be exposed to the ambient environment. The extension leg 3902b, with heater wire section H2 3906b, can be located inside the incubator 3908 and typically exposed to a temperature elevated compared to the ambient environment. In the intended configuration shown in Figure 39A, the intermediate connector 3914 can be located at the interface between the incubator 3908 and the ambient environment.

[0275] However, the inspiratory duct 3902 may be susceptible to movement. For example, the incubator 3908 may be moved while the inspiratory duct 3902 is still connected to a patient inside the incubator 3908. In another example, an infant patient inside the incubator 3908 connected to a humidification system may move around. As a result, section 3902c of the inspiratory limb 3902a may be accidentally displaced inside the incubator 3908, as indicated by the arrow in Figure 39B. Section 3902c may vary in length.

[0276] In both Figures 39A and 39B, the control algorithms 3500 and 3600 in Figures 35 and 36 can heat loop HW1 (including H1 3906a) to a surface temperature threshold when the error is below a predetermined threshold. The control algorithms 3500 and 3600 can raise the temperature of loop HW2 (including H1 and H2 3906a and 3906b) to maintain the patient end setpoint when the error is greater than a predetermined threshold. The increased temperature inside the incubator 3908 can reduce the need to increase the duty cycle of HW2, resulting in loop HW1 having a high duty cycle for most of the heating. When section 3902c is part of loop HW1, since HW1 is primarily heated in the main control scheme, section 3902c can have a higher surface temperature than the extension limb 3902b.

[0277] However, when the humidification system is under low flow rate conditions and section 3902c is inside the incubator as shown in Figure 39B, the surface temperature difference between section 3902c and extension limb 3902b may be greater than when section 3902c is outside the incubator 3908 as shown in Figure 39A. Since gas can be delivered to infants at lower flow rates than to adults, low flow rate conditions may occur more frequently in neonatal treatment mode. Those skilled in the art will understand that gas can be delivered to other patients at low flow rates. In some embodiments, low flow rate may occur when the flow rate is below a predetermined value. In some embodiments, low flow rate may occur when the flow rate is between approximately 2.4 liters per minute (lpm) and less than approximately 5 lpm. In some embodiments, low flow rate may occur when the flow rate is less than approximately 5 lpm. In some embodiments, low flow rate may occur when the flow rate is less than approximately 3.5 lpm. In some embodiments, low flow rate may occur when the flow rate is less than approximately 3 lpm. The definition of low flow rate conditions is not limiting. Low flow rate conditions can increase heat loss from the gas because it takes longer for the gas to travel through the intake line 3902. The patient end sensor 3904b may also take longer to detect the presence of heated gas. Greater heat loss and / or delays in detecting elevated patient end temperatures can result in a large error between the measured patient end temperature and the patient end setpoint. This large error may cause the control unit to output a higher HW2 duty cycle than under normal or high flow rate conditions until the surface temperature threshold of the inspiratory limb 3902a, including section 3902c inside the incubator 3908, is reached.

[0278] One concern regarding section 3902c inside incubator 3908 when the system is under low flow conditions is that section 3902c may overheat. Overheating can result from the difficulty of heat dissipation inside incubator 3908. Heat loss inside the incubator is proportional to the difference between the incubator temperature and the surface temperature of section 3902c. The increased temperature inside the incubator reduces the difference between the incubator temperature and the surface temperature of section 3902c. Therefore, a small amount of heat generated by the loop HW1 portion within section 3902c due to a higher HW1 duty cycle under low flow conditions can be transferred into the incubator. Rather, heat can accumulate on the surface of section 3902c. Heat accumulation on the surface of section 3902c can be significant because the heater wires 3906a and 3906b are embedded in the wall 3916 of the intake pipe 3902. Due to accumulated heat, the surface temperature of section 3902c inside the incubator may exceed the surface temperature threshold.

[0279] Overheating of section 3902c can be dangerous to patients inside incubator 3908 because section 3902c is closer to the patient here than when it is outside incubator 3908. Overheating of section 3902c can also lead to non-compliance with regulatory standards or temperature standards set by the regulatory authority if a surface temperature threshold is mandated by the regulatory authority's regulatory standards or temperature standards. Therefore, it is important under low flow conditions to prevent section 3902c from exceeding the surface temperature threshold when it is moved inside incubator 3908.

[0280] Figure 40 shows a control algorithm 4000 for addressing overheating of section 3902c under low flow rate conditions. The control algorithm 4000 can reduce the likelihood of the surface temperature of section 3902c exceeding a surface temperature threshold, even if section 3902c is moved inside the incubator 3908. The control algorithm 4000 can have the same features as the control algorithm 3600 in Figure 36, except as described below. Therefore, the features of the control algorithm 4000 in Figure 40 can be incorporated into the features of the control algorithm 3600 in Figure 36, and vice versa. Based on the control algorithm 4000, the duty cycle or power supplied to either HW1 and / or HW2 is capped using a suitable upper or lower limit that prevents the surface temperature from exceeding a predetermined threshold. The duty cycle upper or lower limit is predefined in the control algorithm 4000. The duty cycle upper or lower limit may be defined as a percentage or a specific value. Limits or upper limits may be defined based on system parameters or based on the system model. In the example in Figure 40, the upper limits or limits may be hardcoded or predefined. In an alternative configuration, the system may include temperature sensors located in a portion of the pipe or at an intermediate connector. The system may include a first temperature sensor located in a portion of the first section to determine the surface temperature of the first section, and a second temperature sensor located in the second section to determine the surface temperature of the second section. The control algorithm 4000 may be modified to determine duty cycle upper limits or limits based on the measured surface temperature values.

[0281] As shown in Figure 40, a control device of the humidification system, such as the control device 122 shown in Figure 1, can determine the error between the measured patient end temperature and the patient end setpoint in step 4002, and perform a series of checks in steps 4010, 4015, 4020, and 4025. These checks ensure that all sensors and alarms are activated and the system is operational. These checks are optional. A reset 4005 can be performed to clear the outputs and error integrals of both the HW1 and HW2 duty cycles if the control device detects any problem in any of steps 4010, 4015, 4020, or 4025.

[0282] Continuing to refer to Figure 40, after determining that the patient end temperature is below the setpoint and after a series of optional confirmations, the control unit can determine the output of the HW2 duty cycle required to bring the system to the patient end setpoint temperature. The control unit may implement a PID control scheme for the output of the HW2 duty cycle in step 4030. In an exemplary embodiment, the PID control step 4030 may be performed by a PID control scheme described herein and shown in Figure 37. Based on the PID control in step 4030, the control unit may output an HW2 duty cycle in step 4035 with a range limited to 0% to 100%. In a non-limiting example, the duty cycle of HW2 may be limited to a range of 70% upper limit, i.e., 70% of the maximum power that can be supplied by the drive circuit. The 70% upper limit or limit is set to ensure that the surface temperature of the tube, i.e., both sections of the tube, does not exceed a surface temperature threshold.

[0283] Algorithm 4000 may also use the output of the HW2 duty cycle to control the output of the HW1 duty cycle after filtering the raw output of the HW2 duty cycle in step 4045 as described above. The control device may determine a PID limit for the output of the HW1 duty cycle in step 4040. In exemplary embodiments, the control algorithm 4000 may have a flow control component including steps 4050, 4050H, and 4050L. Specifically, the control device may first determine in step 4050 whether the flow rate of the system is higher than a predetermined threshold. In some embodiments, the flow rate may be measured using an integrated flow sensor located in the humidifier housing. In some embodiments, the flow sensor may be located at the outlet and / or inlet of the humidifier.

[0284] The control device can branch the calculation of the maximum output of the HW1 duty cycle based on comparing the measured flow rate with a predetermined threshold. The maximum output of the HW1 duty cycle can be calculated using a function that includes a high-flow or low-flow maximum upper limit output of the HW1 duty cycle and a range-limited output of the HW2 duty cycle. The low-flow maximum upper limit output of the HW1 duty cycle ("low-flow upper limit") may be less than the high-flow maximum upper limit output of the HW1 duty cycle ("high-flow upper limit"). If the measured flow rate is higher than the predetermined threshold, the control device can calculate the maximum output of the HW1 duty cycle from the high-flow upper limit in step 4050H. If the measured flow rate is less than or equal to the predetermined threshold, the control device can calculate the maximum output of the HW1 duty cycle from the low-flow upper limit in step 4050L. In one embodiment, the determination of the output of the HW1 duty cycle may also include a term to compensate for the difference in resistance between two heater wire sections H1 and H2. In a non-limiting example, the low flow limit for the HW1 duty cycle is capped at 37% of the maximum available power output expected from the drive circuit.

[0285] In some embodiments, the low flow rate limit may not affect the output of the HW2 duty cycle. The output of the HW2 duty cycle can reach 100% despite the low flow rate limit. In one embodiment, if the output of the HW2 duty cycle is between 0% and the low flow rate limit, the output of the HW1 duty cycle may be the difference between the low flow rate limit and the output of the HW2 duty cycle; if the output of the HW2 duty cycle is greater than or equal to the low flow rate limit, the output of the HW1 duty cycle may be 0%. Since the output of the HW2 duty cycle can be controlled by the patient end temperature, which is much lower than the surface temperature threshold, the low flow rate limit does not need to affect the output of the HW2 duty cycle. Furthermore, the elevated temperature inside the incubator 3908 can reduce the need for a very high HW2 duty cycle to maintain the patient end temperature.

[0286] In some embodiments, since a smaller amount of gas flows through the intake line at a lower flow rate, the amount of condensation generated in the intake line can be kept low, even though the low flow rate limit may reduce the amount of heat available to minimize condensation. Furthermore, better thermal insulation can be provided to the intake limb to compensate for the less heat generated due to the low flow rate limit.

[0287] The branching at steps 4050H and 4050L ensures that under high flow conditions, loop HW1 is still heated to the surface temperature threshold, but under low flow conditions, it is heated to a lesser extent, as determined by the low flow limit. In a non-limiting example, loop HW1 is heated to the surface temperature threshold based on the duty cycle limit applied to the output supplied to HW1. The branching is advantageous because displacement of section 3902c inside incubator 3908 cannot lead to overheating of section 3902c under high flow conditions. However, the low flow limit is necessary to reduce the maximum HW1 duty cycle under low flow conditions so that even if section 3902c moves inside incubator 3908, the surface temperature of section 3902c does not exceed the surface temperature threshold.

[0288] After calculating the maximum output of the HW1 duty cycle from either step 4050H or 4050L, the control unit can determine in step 4055 whether the calculated maximum output of the HW1 duty cycle is negative. If the calculated maximum output of the HW1 duty cycle is negative, the control unit can set the maximum output of the HW1 duty cycle to 0% in step 4060. If the calculated maximum output of the HW1 duty cycle is not negative, the control unit can limit the output range of the HW1 duty cycle to 0% (or more) to the maximum output limit of the HW1 duty cycle (or less) in step 4075. In some embodiments, the maximum output limit of the HW1 duty cycle can be calculated by subtracting the output of the HW2 duty cycle from 100%.

[0289] Based on the PID limits calculated in step 4040, the control unit can perform PID control of the HW1 duty cycle output in step 4080. The control unit can then output the HW1 duty cycle in step 4085. In one embodiment, the control unit can use the PID control scheme shown in Figure 37 to perform PID control of the HW1 duty cycle output. The control unit can reset the system after PID control of the HW1 duty cycle output in step 4080 (4005).

[0290] Moving to Figure 41, another exemplary flow control component 4150 can be implemented in the control algorithm described herein. The flow control component 4150 can be implemented in control algorithm 3500 as part of step 3525, or in control algorithm 3600 as part of step 3650. The flow control component 4150 can also replace steps 4045, 4050H, and 4050L of control algorithm 4000.

[0291] In the flow control component 4150, the control device can utilize different thresholds to determine whether the maximum output of the HW1 duty cycle should be calculated using a high flow limit or a low flow limit. First, in step 4152, the control device can determine whether the system is currently below the high flow limit or the low flow limit in order to calculate the maximum output of the HW1 duty cycle.

[0292] If the system is currently below the high flow limit, the control unit may determine in step 4154 whether the measured flow rate is higher than a predetermined low flow threshold. If the measured flow rate is higher than the predetermined low flow threshold, the control unit may continue to calculate the maximum output of the HW1 duty cycle using the high flow limit in step 4150H. If the measured flow rate drops below the predetermined low flow threshold, the control unit may switch to step 4150L to calculate the maximum output of the HW1 duty cycle using the low flow limit.

[0293] If the system is currently below the low flow limit, the control unit can determine whether the measured flow rate is below a predetermined high flow threshold. If the measured flow rate is below the predetermined high flow threshold, the control unit can continue to calculate the maximum output of the HW1 duty cycle using the low flow limit in step 4150L. If the measured flow rate reaches or exceeds the predetermined high flow threshold, the control unit can switch to step 4150H to calculate the maximum output of the HW1 duty cycle using the high flow limit.

[0294] In some embodiments, the high flow threshold may be higher than the low flow threshold. The low and high flow thresholds can be determined experimentally. In some embodiments, the thresholds may be specific to the device or sensor. In some embodiments, the low flow threshold may be about 2.4 lpm to about 5 lpm. In some embodiments, the low flow threshold may be about 3.5 lpm. In some embodiments, the low flow threshold may be about 5 lpm. In some embodiments, the high flow threshold may be about 6.5 lpm. By switching the duty cycle upper limit with different flow thresholds when the system is transitioning from low flow conditions to high flow conditions, oscillations at the low / high flow boundary can be reduced.

[0295] Additional embodiments of midpoint / intermediate PCB design Figure 42 shows another exemplary intermediate PCB 4250 with intermediate connectors 214, 3514. A detailed explanation of how the intermediate PCB can be assembled within the intake limb is described above in relation to Figures 32A-32C. The intermediate PCB 4250 may include a diode 4265. The diode 4265 can enable control of HW1 or HW2 depending on the polarity of the supplied voltage, as shown in Figures 25A-25C. Unlike PCB 250 in Figures 14A and 14B, the intermediate PCB 4250 does not need to have a thermistor. The absence of a thermistor can be advantageous in that it can allow the control unit to function more efficiently.

[0296] As shown in Figure 42, the intermediate PCB 4250 may have a substantially rectangular shape with two long sides 4254, 4256 and two short sides 4258, 4260. The diode 4265 may be located near the long side 4256 and near the midpoint of the long side 4256. The intermediate PCB 4250 may include connection pads 4252 for connecting heater wires and / or sensors. The connection pads 4252 may be configured to be located on the same side of the intermediate PCB 4250 and on both the front side (shown in Figure 42) and the back side (not shown) of the slot 4253. As shown in Figure 42, the front side of the intermediate PCB 4250 may have two sets of four connection pads 4252 along the long side 4254, along with two connection pads on each side of the diode 4265. The intermediate PCB 4250 may further have positioning slots 4264 on each of the short sides 4258, 4260. Positioning slots can assist in aligning the PCB during molding. Having two positioning slots can reduce rotation or movement of the PCB during molding. The shape of the slots, the intermediate PCB 4250, and the configuration of the connecting pads 4252 can advantageously enable easier fabrication and assembly of the intermediate PCB 4250. The shape of the intermediate PCB 4250 and the configuration of the connecting pads 4252 can reduce the possibility of short circuits and noise. The short sides 4258 and 4260 of the intermediate PCB 4250 can each have an oblique edge 4262 where the short sides 4258 and 4260 intersect with the long side 4256. The oblique edge 4262 can help maintain a good gas flow profile. In addition, due to the reduced length of the short sides, the intermediate PCB 4250 does not extend through the entire diameter of the intake limb, but can extend over approximately one-third of the diameter. The shorter sides 4258 and 4260 can advantageously reduce the flow resistance (as described above) within the inspiratory limb.

[0297] Additional Embodiments of Patient End Connector PCB Design Figure 43 shows another exemplary patient-end PCB 4370 of the patient-end connector. The patient-end PCB 4370 can function in the same way as the patient-end PCB 270 in Figure 15A. However, the patient-end PCB 4370 may be longer than the patient-end PCB 270 in Figure 15A to facilitate molding. The patient-end PCB 4370 may also have positioning slots so that the PCB 4370 can be mounted on the assembly in only one orientation to facilitate assembly. As shown in Figure 43, the patient-end PCB 4370 may have multiple upper positioning slots 4373 and lower positioning slots 4375. The positioning slots can help align the PCB during molding. Any portion of the PCB 4370 below the upper positioning slots 4373 or below the lower positioning slots 4375 can be broken off when the PCB 4370 is assembled.

[0298] The patient end PCB 4370 may also include connection pads 4372 for heater wires and sensor connection wires. The connection pads 4372 can be configured to be located at either end of the patient end PCB 4370. In an exemplary embodiment, the patient end PCB 4370 may have two connection pads 4372 on the front side of the slot 4373. Although not shown in Figure 43, the patient end PCB 4370 may also have two connection pads 4372 on the back side of the slot 4373. Having connection pads 4372 at either end of the PCB 4370 can advantageously prevent or reduce water ingress. The patient end PCB 4370 may also have a thermistor 4374. Unlike the patient end PCB 270 in Figure 15A, the thermistor 4374 in the patient end PCB 4370 may be located near the center of the patient end PCB 4370. In some embodiments, the patient end PCB 4370 may have a track that extends substantially linearly from the connecting pad 4372 to thermistor 4374. Those skilled in the art will understand that any preferred configuration of the track can be placed on the patient end PCB 4370. Furthermore, the position of the thermistor 4374 can allow for easier fabrication of the PCB 4370.

[0299] In some embodiments, the lower positioning slot 4375 may not be present. In other embodiments, the patient end PCB 4370 may not include the portion below the upper positioning slot 4373. In one embodiment, the patient end PCB 4370 may not be molded and may terminate below the upper positioning slot 4373.

[0300] Chamber End PCB Design Embodiment Figures 44A and 44B show an exemplary chamber end PCB 4490 for connecting to a complementary connector in a cartridge (shown in Figure 8A) which may include an electrical connection pad. A detailed description of the shape and function of the chamber end PCB is given in U.S. Patent Application No. 15 / 105,531, “HUMIDIFICATION SYSTEM CONNECTIONS,” filed June 16, 2016; and U.S. Patent Application No. 15 / 021,673, filed March 11, 2016; each of these is incorporated herein by reference in whole. As shown in Figure 44B, which shows a detailed view of the upper portion of the chamber end PCB 4490, the chamber end PCB 4490 may have a connection pad 4492 on the same side. In the non-limiting examples shown in Figures 44A and 44B, the chamber end PCB 4490 may have four connection pads 4492 located on the right side of the PCB 4490. In other embodiments, all connection pads may be located on the left side or any other preferred side of the PCB 4490. The PCB 4490 is plasma-treated to reduce water ingress.

[0301] As clearly shown in Figure 44B, the connecting pad 4492 can be angled. The chamber end PCB 4490 may also have deeper slots 4494 than those described in U.S. Patent Application No. 15 / 021,673 and U.S. Patent Application No. 15 / 105,531, which are referenced above. The deep slots 4494 and angled connecting pads 4492 can advantageously allow for correct and even wire tension to reduce the risk of the wire moving around. The chamber end PCB 4490 may also accommodate flattened tags that are raised at a certain angle and positioned straight on top of the chamber end PCB 4490.

[0302] Exemplary Embodiments The following 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 embodiments. Further embodiments may be formed by removing, adding, or combining various features of the exemplary embodiments listed, and such embodiments are also part of this disclosure. 1. A medical tube having the first classification of medical tubes, wherein the first classification is, A first structure forming a pipeline configured to transport humidifying gas, Equipped with a first heater wire circuit, Medical tubing further comprises a second classification of medical tubing, and the second classification is, A second structure forming a pipeline configured to transport humidifying gas, Equipped with a second heater wire circuit, The medical tubing further includes an intermediate connector having a connection circuit that electrically couples a first heater wire circuit to a second heater wire circuit, the intermediate connector being coupled to the patient end of the first section of the medical tubing and the chamber end of the second section of the medical tubing to form a single conduit for humidifying gas. At least a portion of the intermediate connector is covered by a portion of the first section of the medical conduit and / or a portion of the second section of the medical conduit, such that the intermediate connector is inside the medical conduit. In the first mode, power passes through the connecting circuit to supply power to the first heater wire circuit but not to the second heater wire circuit, and in the second mode, power passes through the connecting circuit to supply power to both the first and second heater wire circuits. Medical tubing. 2. A medical tube in Embodiment 1, in which the connection circuit includes a diode. 3. A medical tube in embodiment 1 or 2, further comprising a first sensor positioned at the patient end of the first section. 4. A medical tube in Embodiment 3, wherein the first sensor is either a temperature sensor or a humidity sensor. 5. A medical tube in any one of embodiments 1 to 4, further comprising a second sensor positioned at the patient end of a second section of the medical tube. 6. A medical tube in Embodiment 5, wherein the second sensor is either a temperature sensor or a humidity sensor. 7. The first structure comprises an elongated tube, and the elongated tube is A first elongated member comprising a hollow body spirally wound to form at least a portion of a conduit having a longitudinal axis, a lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen, A second elongated member is joined by being spirally wound between adjacent turns of a first elongated member, and the second elongated member forms at least a portion of the lumen of the elongated tube. A medical tube in any one of embodiments 1 to 6, comprising the features described above. 8. A medical tube in Embodiment 7, wherein the first elongated member forms a plurality of air bubbles having a flattened surface in its lumen in a longitudinal cross-section. 9. A medical tube in embodiment 8 in which adjacent air bubbles are separated by a gap above the second elongated member. 10. A medical tube in Embodiment 8 in which adjacent air bubbles are not directly connected to each other. 11. A medical tube in Embodiment 8 having multiple air bubbles with perforations. 12. An inspiratory limb comprising: a first section of an inspiratory limb having a first heater wire circuit; a second section of an 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 the patient end of the first section; and a second sensor positioned at the patient end of the second section. Control device and A respiratory humidification system comprising, The control unit is adapted to selectively switch between a first mode and a second mode, in which the control unit provides power to a first heater wire circuit through a connector circuit, and in which the control unit provides power to both the first and second heater wire circuits. A humidifying system for breathing. 13. A system in embodiment 12 in which switching is performed based on input from one or both sensors. 14. A system in Embodiment 13 in which the input from one or both sensors includes one or more of temperature, flow rate, humidity, and power. 15. A system in any one of embodiments 12 to 14 in which the first and second modes are defined by the direction of the current supplied by the power supply. 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, in which the control device reads a signal from the second sensor, and in which the control device reads signals from both the first sensor and the second sensor. 17. A system in any one of embodiments 12 to 16, wherein the first sensor and the second sensor are temperature sensors. 18. An inspiratory limb comprising: a first section of an inspiratory limb having a first heater wire circuit; a second section of an 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 the patient end of the first section; and a second sensor positioned at the patient end of the second section. Exhalation limbs and Interfaces connected to the inspiratory and expiratory limbs, Control device and A dual-library circuit comprising, The control unit is adapted to selectively switch between a first mode and a second mode, in which the control unit provides power to a first heater wire circuit through a connector circuit, and in which the control unit provides power to both the first and second heater wire circuits. Double limb circuit. 19. A dual limb circuit in embodiment 18 in which the exhaling limb is equipped with an exhalation heater wire circuit. 20. A dual limb circuit in Embodiment 19 in which the exhaling limb is heated using an exhalation heater wire circuit. 21. A dual limb circuit in Embodiment 19 in which the exhalation heater wire circuit is powered in parallel with the first heater wire circuit in the first section of the inspiratory limb. 22. A dual-library circuit in Embodiment 21, in which the exhalation 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. A dual-library circuit in any one of embodiments 18 to 22 in which the interface is connected via a Y-piece. 24. A segmented inspiratory limb configured to be heated along at least two sections, wherein each section of the inspiratory limb is A first elongated member comprising a hollow body spirally wound to form at least a portion of an elongated tube having a longitudinal axis, a lumen extending along the longitudinal axis, and a hollow wall surrounding the lumen, A second elongated member is joined by being spirally wound between adjacent turns of a first elongated member, and the second elongated member forms at least a portion of the lumen of the elongated tube. A segmented inspiratory limb equipped with a symmetrical inspiratory limb. 25. A medical tube having two sections, where each section is, An elongated hollow body that is 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, wherein in a transverse cross-section, the elongated hollow body has a wall that defines at least a portion of the hollow body, A reinforcing portion that is spirally positioned between adjacent turns of an elongated hollow body, extending along the length of the elongated hollow body, and forming a part of the lumen of the elongated tube, One or more conductive filaments embedded or encapsulated inside the reinforcement portion and Equipped with, The reinforcing portion is relatively thicker or rigider than the wall of the elongated hollow body. The medical tubing further includes a partition connector attached to the first partition, and the partition connector is A connecting pad configured to electrically connect the conductive filament from the first section to the conductive filament from the second section when the first section is physically connected to the second section, A power diode electrically coupled to the conductive filament of the first section and Equipped with, The power diode, when provided with an electrical signal of first polarity, is configured to supply power to the conductive filament of the first section and not to the conductive filament of the second section. The power diode is configured such that when an electrical signal of the second polarity is provided, power is supplied to the conductive filament of the first section and the conductive filament of the second section. Medical tubing. 26. A first heater wire input connection wire configured to be electrically coupled to the first input heater wire, A second heater wire input connection wire configured to be electrically coupled to the second input heater wire, A first heater wire output connection wire is configured to be electrically coupled to a first output heater wire and to be electrically coupled to a first heater wire input connection wire, A second heater wire output connection wire is configured to be electrically coupled to the second output heater wire and to be electrically coupled to the second heater wire input connection wire, A first signal wire input connection wire configured to be electrically coupled to a first input signal wire, A second signal wire input connection wire configured to be electrically coupled to a second input signal wire, A first signal wire output connection line is configured to be electrically coupled to a first output signal wire and electrically coupled to a first signal wire input connection line, A second signal wire output connection wire is configured to be electrically coupled to a second input signal wire and electrically coupled to a second signal wire input connection wire, A power diode electrically coupled to a first heater wire input connection line and a second heater wire input connection line, 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 line, A signal diode electrically coupled to a sensor and a second signal wire input connection line, wherein the signal diode allows current to flow from the second input signal wire through the sensor to the first input signal wire, and prevents current from flowing from the first input signal wire through the sensor to the second input signal wire. A connector equipped with these features. 27. An inspiratory limb comprising a first section having a first heater wire, a second section having a second heater wire, and a sensor positioned at the patient end of the second section for measuring patient end parameters, wherein the first and second heater wires are electrically coupled, the first heater wire forms a first heater circuit, and the first and second wires form a second heater circuit, A hardware control device configured to receive the output of the sensor, further configured to provide power to the first heater circuit when the difference between the output of the sensor and the patient end parameter setting point is less than a predetermined threshold, and to provide power to the second heater circuit when the difference between the output of the sensor and the patient end parameter setting point is greater than or equal to the predetermined threshold; A respiratory humidification system comprising, The hardware control device is configured to provide maximum power to the first heater circuit when the hardware control device provides power to the first heater circuit. A humidifying system for breathing. 28. An inspiratory limb comprising a first section having a first heater wire, a second section having a second heater wire, and a sensor positioned at the patient end of the second section for measuring patient end parameters, wherein the first and second heater wires are electrically coupled, the first heater wire forms a first heater circuit, and the first and second wires form a second heater circuit, and the first and second heater wires are configured to heat the respiratory gas passing through the inspiratory limb. A respiratory humidification system comprising, The first and second heater wires are configured to communicate with a hardware processor which is configured to execute software instructions causing the processor to control the first and second heater circuits. The processor is configured to heat the breathing gas using the first heater circuit until the first heater wire reaches a maximum temperature when the difference between the output of the sensor and the patient end parameter setpoint is less than a predetermined threshold, and the processor is configured to heat the breathing gas using the second heater circuit when the difference between the output of the sensor and the patient end parameter setpoint is greater than or equal to the predetermined threshold. A humidifying system for breathing. 29. A hardware processor configured to communicate with a first heater wire circuit in a first segment of an inspiratory limb and a second heater wire circuit in a second segment of the inspiratory limb, wherein the hardware processor is also configured to communicate with a connector circuit in an intermediate connector configured to electrically connect the first heater wire circuit to the second heater wire circuit, and the hardware processor is further configured to communicate with a first sensor located at the patient end of the first segment and a second sensor located at the patient end of the second segment. A respiratory humidification system comprising, The hardware processor is configured to execute software instructions that cause the processor to selectively switch between a first mode and a second mode. In the first mode, the processor provides power to the first heater wire circuit through the connector circuit, and in the second mode, the processor provides power to the first and second heater wire circuits. A humidifying system for breathing. 30. An inspiratory limb comprising: a first section of the inspiratory limb having a first heater wire circuit; a second section 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 the patient end of the first section; and a second sensor positioned at the patient end of the second section. A respiratory humidification system comprising, The first and second heater wire circuits, the connector circuit, and the first and second sensors are each configured to communicate with a hardware control device, and the hardware control device is adapted to selectively switch between a first mode and a second mode. In the first mode, the hardware control device provides power to the first heater wire circuit through the connector circuit, and in the second mode, the hardware control device provides power to the first and second heater wire circuits. A humidifying system for breathing. 31. An inspiratory limb comprising: a first section of the inspiratory limb having a first heater wire circuit; a second section 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 the patient end of the first section; and a second sensor positioned at the patient end of the second section. Exhaling limbs and Interfaces connected to the inspiratory limb and the expiratory limb A dual-library circuit comprising, The first and second heater wire circuits, the connector circuit, and the first and second sensors are each configured to communicate with a hardware control device, and the hardware control device is adapted to selectively switch between a first mode and a second mode. In the first mode, the hardware control device provides power to the first heater wire circuit through the connector circuit, and in the second mode, the hardware control device provides power to the first and second heater wire circuits. Double limb circuit. 32. A heater circuit comprising a first heater, a second heater, a first switch pair, a second switch pair, and a power supply. A respiratory humidification system comprising, The heater circuit is configured to communicate with a hardware control module, and the hardware control module is adapted to control the flow of current from the power supply to the first heater by selectively opening and closing the first pair of switches, and to control the flow of current from the power supply to the second heater by selectively opening and closing the second pair of switches, The first pair of switches and the second pair of switches can be opened and closed independently of each other, thereby enabling independent control of the first and second heaters. A humidifying system for breathing. 33. A hardware processor configured to communicate with a heater circuit comprising a first heater, a second heater, a first switch pair, a second switch pair, and a power supply. A respiratory humidification system comprising, The hardware processor is configured to execute software instructions...

Claims

1. Medical tubing, A first section comprising a first heater wire, wherein the first heater wire forms a first heater circuit, A second section comprising a second heater wire, wherein the second heater wire is electrically coupled to the first heater wire, the first and second heater wires form a second heater circuit, and the first and second heater wires are configured to heat the breathing gas passing through the medical tube, The device comprises a temperature sensor positioned at the patient end of the second section for measuring the patient end temperature, The first and second heater wires and the temperature sensor are configured to communicate electrically with a hardware processor, and the processor is configured to execute software instructions that cause the processor to control the first and second heater circuits. The medical tubing operates as a single tubing when the first and second sections of the medical tubing are exposed to the same ambient environment, and operates as a divided tubing when the first and second sections of the medical tubing are exposed to different ambient environments. A medical tube, wherein the processor is configured to control the first and second heater circuits to achieve a desired temperature setpoint at the patient end of the second section, and the processor is configured to control the first and second heater circuits differently depending on whether the medical tube operates as a single tube or as a sectioned tube.

2. The medical tube according to claim 1, wherein the processor is configured to control the duty cycle of at least the first heater circuit and the second heater circuit to achieve the desired temperature setpoint at the patient end of the second section.

3. The aforementioned processor, Determine the error between the patient end temperature measured by the temperature sensor and the desired temperature set point. Based on the aforementioned error, the output of the duty cycle of the first and second heater circuits is determined and controlled using PID. A medical tube according to claim 2, configured as described above.

4. The medical tube according to claim 3, wherein, when the medical tube operates as a single tube, the processor is configured to control the output of the duty cycle of the second heater circuit until the error is within an appropriate error threshold.

5. The medical tube according to claim 4, wherein the processor is configured to use the second heater circuit as the primary means for controlling heating within the medical tube.

6. The medical tube according to claim 4 or 5, wherein the output of the duty cycle of the first heater circuit is inversely correlated with the output of the duty cycle of the second heater circuit.

7. The medical tube according to claim 6, wherein the output of the duty cycle of the first heater circuit is set to 0%.

8. The medical tube according to claim 4, wherein, if the error is within the appropriate error threshold, the processor is configured to control the output of the first heater circuit to achieve temperature control.

9. The medical tube according to claim 3, wherein, when the medical tube operates as a segmented tube, the processor is configured to control the output of the duty cycle of the first heater circuit when the error is within the appropriate error threshold.

10. The medical tube according to claim 9, wherein the error threshold value is 2.5°C or less.

11. The medical tube according to claim 9 or 10, wherein the processor is configured to use the first heater circuit as the primary means for controlling heating within the medical tube.

12. If the error is greater than the appropriate error threshold, the processor controls the output of the second heater circuit, as described in claim 11.

13. The medical tube according to claim 12, wherein the output of the duty cycle of the second heater circuit is set to 0%.

14. The medical tube according to claim 8, wherein the processor is configured to communicate with at least one sensor that measures the temperature of the external surface of the medical tube and to control the output of the first heater circuit so as to energize the first heater wire to its maximum capacity until a predetermined surface temperature threshold is reached.

15. The medical tube according to claim 1, wherein the processor is configured to control the output of the first heater circuit to achieve the temperature of the end opposite the patient end in the second section, such that a temperature drop across the entire second section can bring a desired temperature setpoint to the patient end of the second section.

16. The medical tube according to claim 15, wherein the processor is configured to control the output of the duty cycle of the first heater circuit based on the difference between the chamber outlet temperature and the patient end temperature measured by the temperature sensor.

17. The medical tube according to claim 1, wherein the second section of the medical tube is adapted to be placed inside a controlled environment, and the medical tube is configured to operate as a sectioned tube when the second section of the medical tube is placed inside the controlled environment.

18. The medical tube according to claim 17, wherein the controlled environment comprises one of an incubator, a temperature-controlled system, and a region having at least two different temperature zones.

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