Wire heated tube for a breathing apparatus

Abstract

It is an object of the present invention to provide a wire heated tube for a respiratory device.SOLUTION: An air delivery conduit for use in an apparatus for delivering breathable pressurized air includes a tube, a first wire, a second wire, a first cuff, and a second cuff. The first wire extends at least partially between the first end and the second end of the tube. The first wire has a first diameter. The second wire extends at least partially between the first end and the second end. The second wire has a second diameter different from the first diameter. The first cuff is coupled to the first end of the tube. The second cuff is coupled to the second end of the tube and includes a thermistor connected to the first wire and a fastener projecting from an inner surface of the second cuff into a flow path of the supply of pressurized breathing air. The thermistor is housed within the fixture.SELECTED DRAWING: Figure 21

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 745,799, filed October 15, 2018, the entirety of which is incorporated herein by reference.

[0002] This application incorporates the teachings of U.S. Patent No. 9,572,949, filed January 31, 2014, and U.S. Patent No. 9,903,371, filed August 28, 2009 (attached hereto), as if both patents were set forth in their entireties herein.

[0003] [Field] The present technology relates to heated air delivery conduits for use in respiratory systems, such as invasive and non-invasive ventilation, continuous positive airway pressure (CPAP), bilevel therapy and treatment of sleep-disordered breathing (SDB) conditions such as obstructive sleep apnea (OSA), and various other respiratory diseases and illnesses. [Background technology]

[0004] Respiratory devices are typically designed to vary the humidity of the breathing gas to reduce drying of the patient's airway and the associated discomfort and complications. The use of a humidifier positioned between the flow generator and the patient mask produces humidified gas that minimizes drying of the nasal mucosa and increases patient airway comfort. Additionally, in cool climates, warm air, which may be accidentally created by a leak, is more comfortable in and around the face area than cold air.

[0005] The humidified air can cool on its way from the humidifier to the patient, causing condensation on the inside of the conduit, known as "rainout." To address this, it is known to provide additional heating of the gas delivered to the patient by means of a heating wire circuit incorporated into the wall of the wire heated tube. Summary of the Invention [Means for solving the problem]

[0006] [Brief explanation of the technology] According to one embodiment, an air delivery conduit includes a tube, a first wire and a second wire within the tube, and a thermistor connected to the first wire, wherein the first wire includes a first diameter and the second wire includes a second diameter different from the first diameter.

[0007] In some embodiments, a third wire is disposed within the vessel and includes a third diameter that is different from the first diameter.

[0008] In some embodiments, a fourth wire is disposed within the vessel and includes a fourth diameter that is the same as the first diameter.

[0009] According to one aspect, a control system for a heated conduit includes a sensing circuit configured to indicate a temperature of a sensor positioned within the heated conduit, the sensing circuit including a first wire having a first diameter and a second wire having a second diameter different from the first diameter.

[0010] According to one aspect, a sensing circuit for a heating conduit includes a sensing wire and a heating wire coupled to a heating circuit for the heating conduit. The sensing circuit also includes a temperature sensor coupled to the sensing wire and configured to measure a temperature of the heated conduit. The sensing wire has a first diameter and the heating wire has a second diameter different from the first diameter.

[0011] In some embodiments, a second heating wire is coupled to the heating circuit and includes a third diameter that is different from the first diameter.

[0012] According to one aspect, an air delivery conduit for use in an apparatus for delivering a supply of breathable pressurized air to a patient includes a tube, a first wire, a second wire, a first cuff, and a second cuff. The tube has a first end and a second end. The first wire extends at least partially between the first end and the second end. The first wire has a first diameter. The second wire extends at least partially between the first end and the second end. The second wire has a second diameter different from the first diameter. The first cuff is coupled to the first end of the tube and includes an electrical connector connected to the first wire and the second wire to provide electrical connection with the apparatus. The second cuff is coupled to the second end of the tube. The second cuff includes a thermistor connected to the first wire and a fixture that projects from an inner surface of the second cuff into a flow path of the supply of pressurized breathable air flowing through the second cuff. The thermistor is housed within the fixture.

[0013] In some embodiments, the tube has a helical rib, and the first wire and the second wire are positioned within the helical rib.

[0014] In some embodiments, the electrical connector includes a first terminal corresponding to a first wire and a second terminal corresponding to a second wire, the first terminal and the second terminal being configured to receive contacts of a device.

[0015] In some embodiments, the second cuff further comprises a first end having an inner surface secured to the outer surface of the tube and a second end comprising an elastomeric material that frictionally engages the outer surface of the tubular connector.

[0016] In some embodiments, the first wire and the second wire are electrically connected to one another.

[0017] In some embodiments, the second wire is a heating wire and is made of a low ohmic resistor to apply heat to the tube.

[0018] In some embodiments, a third wire extends at least partially between the first end and the second end, the third wire having a third diameter different from the first diameter.

[0019] In some embodiments, the third wire is a heating wire and is made of a low ohmic resistor to apply heat to the tube.

[0020] In some embodiments, the third wire is electrically connected to the second wire.

[0021] In some embodiments, the third wire is electrically connected to the first wire.

[0022] In some embodiments, the third wire is connected to ground.

[0023] In some embodiments, a first wire monitors the temperature of the air proximate to the second cuff and detects an imbalance between the bridge formed by the second wire and the third wire.

[0024] In some embodiments, the third diameter is equal to the second diameter.

[0025] In some embodiments, a fourth wire extends at least partially between the first end and the second end, the fourth wire having a fourth diameter different from the second diameter.

[0026] In some embodiments, the fourth wire is a sensing wire and is electrically connected to the thermistor and the first wire.

[0027] In some embodiments, the fourth wire is included in a different circuit than the first wire.

[0028] In some embodiments, the fourth wire is connected to ground.

[0029] In some embodiments, the fourth diameter is equal to the first diameter.

[0030] In some embodiments, the second diameter is greater than the first diameter.

[0031] In some embodiments, the first diameter corresponds to 29 gauge on the American Wire Gauge (AWG) standard.

[0032] In some embodiments, the second diameter corresponds to 31 gauge AWG.

[0033] In some embodiments, the tube, the first wire, and the second wire are flexible, and the first diameter increases the overall flexibility of the tube compared to the second diameter.

[0034] According to one aspect, an air delivery conduit for use in an apparatus for delivering a supply of pressurized breathable air to a patient includes a tube, a first wire, a second wire, a third wire, a first cuff, and a second cuff. The tube has a first end and a second end. The first wire extends at least partially between the first end and the second end. The first wire has a first diameter. The second wire extends at least partially between the first end and the second end. The second wire has a second diameter different from the first diameter. The third wire extends at least partially between the first end and the second end. The third wire has a third diameter different from the first diameter. The first cuff is coupled to the first end of the tube and includes an electrical connector connected to the first wire and the second wire to provide electrical connection with the apparatus. A second cuff is coupled to the second end of the tube and includes a thermistor connected to the first wire.

[0035] In some embodiments, a retainer protrudes from the interior surface of the second cuff into the flow path of the supply of pressurized breathable air flowing through the second cuff, and a thermistor is housed within the retainer.

[0036] In some embodiments, the tube has a helical rib, and the first wire, the second wire, and the third wire are positioned within the helical rib.

[0037] In some embodiments, the electrical connector includes a first terminal corresponding to a first wire, a second terminal corresponding to a second wire, and a third terminal corresponding to a third wire, wherein the first terminal, the second terminal, and the third terminal are configured to receive contacts of a device.

[0038] In some embodiments, the first wire, the second wire, and the third wire are electrically connected to one another.

[0039] In some embodiments, the second wire and the third wire are heating wires and are made of low ohmic resistors to apply heat to the tube.

[0040] In some embodiments, the third wire is connected to ground.

[0041] In some embodiments, a first wire monitors the temperature of the air proximate to the second cuff and detects an imbalance between the bridge formed by the second wire and the third wire.

[0042] In some embodiments, the third diameter is equal to the second diameter.

[0043] In some embodiments, the first diameter corresponds to 29 gauge on the American Wire Gauge (AWG) standard.

[0044] In some embodiments, the second diameter corresponds to 31 gauge AWG.

[0045] According to one aspect, an air delivery conduit for use in an apparatus for delivering a supply of pressurized breathable air to a patient includes a tube, a first wire, a second wire, a third wire, a fourth wire, a thermistor, and a fixture. The tube has a first end and a second end. The first wire extends at least partially between the first end and the second end. The first wire has a first diameter. The second wire extends at least partially between the first end and the second end. The second wire has a second diameter different from the first diameter. The third wire extends at least partially between the first end and the second end. The third wire has a third diameter different from the first diameter. The fourth wire extends at least partially between the first end and the second end. The fourth wire has a fourth diameter different from the second diameter. The thermistor is connected to the first wire. The fixture projects from the interior surface of the tube into the flow path of the supply of pressurized breathing air passing through the tube. A thermistor is housed within the fixture.

[0046] In some embodiments, a cuff is coupled to the second end, the cuff including an inner surface and the fastener protruding from the cuff.

[0047] In some embodiments, the first wire and the fourth wire form a sensing circuit, and the second wire and the third wire form a heating circuit that is separate from the sensing circuit.

[0048] In some embodiments, the third wire and the fourth wire are connected to ground.

[0049] In some embodiments, the first diameter is equal to the fourth diameter.

[0050] In some embodiments, the second diameter is equal to the third diameter.

[0051] In some embodiments, the first diameter corresponds to 29 gauge on the American Wire Gauge (AWG) standard.

[0052] In some embodiments, the second diameter corresponds to 31 gauge AWG. Exemplary embodiments will be described with reference to the accompanying drawings. [Brief explanation of the drawings]

[0053] [Figure 1] 1 is a schematic illustration of a PAP system according to one exemplary embodiment. [Figure 2] 1 is a schematic illustration of a PAP system according to another exemplary embodiment. [Figure 3] 1 is a schematic illustration of a PAP system according to another exemplary embodiment. [Figure 4] 1 is a schematic illustration of a PAP system including a flow generator and a humidifier, according to an exemplary embodiment; [Figure 5] The humidifier in Figure 4 is depicted schematically. [Figure 6] The humidifier in Figure 4 is depicted schematically. [Figure 7] The humidifier in Figure 4 is depicted schematically. [Figure 8] 1 is a schematic illustration of a heated tube according to an exemplary embodiment; [Figure 9] 9 is a schematic illustration of the tubing connector or cuff of FIG. 8 at the end of the tubing configured to be connected to a humidifier; [Figure 10] 9 is a schematic illustration of the tubing connector or cuff of FIG. 8 at the end of the tubing configured to be connected to a humidifier; [Figure 11] 9 is a schematic illustration of the tubing connector or cuff of FIG. 8 at the end of the tubing configured to be connected to a humidifier; [Figure 12] 9 is a schematic illustration of the tubing connector or cuff of FIG. 8 at the end of the tubing configured to be connected to a humidifier; [Figure 13] 9 is a schematic illustration of the tubing connector or cuff of FIG. 8 at the end of the tubing configured to be connected to a humidifier; [Figure 14]14A-14C are schematic illustrations of the end of the tube of FIGS. 9-13 connected to the humidifier of FIGS. 5-7; [Figure 15] 9 is a schematic depiction of the end of the tube of FIG. 8 connected to a patient interface; [Figure 16] 9 is a schematic illustration of a tubing connector or cuff of FIG. 8 at the end of the tubing configured to be connected to a patient interface; [Figure 17] 9 is a schematic illustration of a tubing connector or cuff of FIG. 8 at the end of the tubing configured to be connected to a patient interface; [Figure 18] The wiring configuration of the heated tube in Figure 8 is depicted schematically. [Figure 19] 10 is a schematic depiction of an exemplary embodiment of an algorithm for controlling a heated tube; [Figure 20] 10 is a schematic depiction of an alternative wiring configuration for the heated tube; [Figure 21] 10 is a schematic depiction of another alternative wiring configuration for the heated tube; [Figure 22] 10 is a schematic diagram illustrating a circuit for sensing the temperature of a patient interface and providing active overheat protection according to another exemplary embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0054] PAP system

[0055] As shown schematically in FIG. 1 , a PAP (positive airway pressure) system, such as a CPAP (continuous positive airway pressure) system, includes a PAP device (or PAP system or breathing apparatus) 10, an air delivery conduit 20 (also referred to as a tube or tubing), and a patient interface 50. In use, the PAP device 10 generates a supply of pressurized air that is delivered to a patient via the air delivery conduit 20, which includes one end connected to an outlet of the PAP device 10 and an opposite end connected to an inlet of the patient interface 50. The patient interface comfortably engages and provides a seal with the patient's face. The patient interface or mask may have any suitable configuration known in the art, such as, for example, a full face mask, a nasal mask, an oronasal mask, a mouth mask, nasal prongs, or the like. Headgear may also be utilized to comfortably support the patient interface in a desired position on the patient's face.

[0056] In various embodiments, the humidifier may be incorporated or integrated within the PAP device, or may otherwise be provided downstream of the PAP device, in which case an air delivery conduit 20 may be provided between the patient interface 50 and the outlet of the humidifier 15, as shown schematically in FIG.

[0057] It should be understood that the air delivery conduit may be provided in other suitable ways along the air delivery path. For example, as shown schematically in Figure 3, the humidifier 15 may be a separate component from the PAP device 10, with an air delivery conduit 20(1) disposed between the PAP device 10 and the humidifier 15, and another air delivery conduit 20(2) disposed between the humidifier 15 and the patient interface 50.

[0058] Heated humidifiers are commonly used to provide sufficient humidity and temperature to the air for patient comfort. In such embodiments, the air delivery conduit may be heated to heat the gas and prevent "rainout" or condensation from forming inside the conduit as the gas is delivered to the patient. In this arrangement, the air delivery conduit may include one or more wires or sensors associated with the heating.

[0059] As described below, each end of the air delivery conduit includes a cuff that is structured to attach the conduit to a patient interface, a PAP device, and / or a humidifier. The cuffs differ for non-heated and heated conduits; for example, cuffs for heated conduits house sensors or electronics / wiring associated with heating.

[0060] Although the cuff is described as being implemented in a CPAP system of the type described above, it may be implemented in other tubing arrangements for transporting gases or liquids, i.e., the CPAP system is merely exemplary, and various aspects of the present invention may be incorporated into other suitable arrangements.

[0061] Referring to FIGS. 4-7, one exemplary embodiment of a PAP system 10 includes a flow generator, i.e., a blower 12, and a humidifier 15. The flow generator 12 is configured to generate a flow of breathable gas having a pressure of, for example, approximately 2-30 cmH2O. The flow generator includes a power button 2 for turning the PAP system on and off. A display 4 is provided for displaying interactive menus and information related to the operation of the PAP system to a user or operator. A user or operator may select menus and / or information through an input 6, which may be, for example, a button or key. A pushbutton dial 8 may also allow a user or operator to select information and / or menus. The input 6 and the pushbutton dial 8 may be used together to select information and / or menus. For example, one or both of the inputs 6 may be pressed to rotate the dial 8 to display desired information or menus on the display 4, and the dial 8 may then be pressed to select particular information to be displayed or a particular operating mode of the PAP system.

[0062] The humidifier 15 includes a humidifier chamber 16 and a lid 18 pivotable between an open position and a closed position. The humidifier chamber 16 contains a water chamber, or tub 14, which is covered by the lid 18 when the lid 18 is in the closed position. The lid 18 is provided with a seal 19. The lid 18 includes a window 30 to allow visual inspection of the contents of the humidifier tub 14. The seal 19 includes an opening 31 corresponding to the position of the window 30 in the lid 18. When the lid 18 is in the closed position, the seal 19 contacts the tub 14 to ensure good thermal contact between the bottom surface of the tub 14 and a heating plate (not shown) provided at the bottom of the humidifier chamber 16, such as that disclosed in WO 2010 / 031126. The tub 14 includes a base, or bottom, that transfers heat from the heating plate to a water supply provided within the tub 14. Such a vessel is disclosed in WO 2010 / 03112.

[0063] 4 and 5, the humidifier 15 is connectable to the flow generator 12 by a connector or latch 24. The latch 24 may be, for example, a spring-biased latch that engages a corresponding recess (not shown) in the flow generator 12. An electrical connector 26 is provided to electrically connect the flow generator 12 to the humidifier tub 14. Power may be provided from the flow generator 12 to the humidifier tub 14, although it should be understood that the humidifier may be provided with its own power source. Control signals may also be provided from the flow generator 12 to the humidifier tub 14 via the electrical connector 26.

[0064] As shown in FIG. 4 , the tub 14 includes a tub lid (or top) 86 configured to direct the flow of breathable gas generated by the flow generator 12 along a channel 90 provided in the tub lid 86 and through an outlet 92 of the channel 90 into the tub 14. When the humidifier 15 is connected to the flow generator 12 via the latch 24, the humidifier chamber 16 includes an inlet 22 configured to receive the flow of breathable gas generated by the flow generator 12. The inlet 22 directs the flow into a flow path 90 in the tub lid 86 of the humidifier tub 14. The flow is directed by the flow path 90 into an outlet 92 in the humidifier tub 14. The tub 14 includes an outlet 88 for the humidified breathable gas flow. The rear of the humidifier 15 is provided with a tubing connector 70 ( FIG. 7 ) that communicates with the outlet 88. It should be understood that the tubing connector 70 may be provided on the side or front of the humidifier 15. The tubing connector 70 is configured to connect to a hose, tube, or conduit to a tube configured to deliver a humidified flow to a patient interface, such as a mask, as further detailed herein.

[0065] It should be understood that the humidifier 15 may include its own control system or controller, such as, for example, a microprocessor mounted on a printed circuit board (PCB). The PCB may be located in a wall of the humidifier chamber 16 and may include a light, such as an LED, that illuminates the contents of the basin 14 to allow for visual inspection of the water level. It should also be understood that the flow generator 12 constitutes a control system, i.e., controller, that communicates with the humidifier 15 controller when the flow generator 12 and humidifier 15 are electrically connected. It should further be understood that the flow generator and / or humidifier may include multiple sensors, including, for example, an ambient humidity sensor that may be configured to sense absolute ambient humidity and may include an absolute humidity sensor or a temperature sensor for detecting ambient temperature, and a relative humidity sensor for sensing relative humidity from which the ambient absolute humidity can be calculated. The plurality of sensors may also include, for example, an ambient pressure sensor for sensing ambient pressure, a flow sensor for sensing the flow of breathable gas generated by the flow generator, and / or a temperature sensor for detecting the temperature of the water supply contained in the basin 14 of the humidifier 15 or the temperature of the heating plate of the humidifier 15. Such an arrangement is shown, for example, in U.S. Patent Application Publication No. 2009 / 0223514 A1. The PAP system 10 may be operated according to various control algorithms stored in the controllers of the flow generator 12 and / or the humidifier 15. Such control algorithms are disclosed, for example, in U.S. Patent Application Publication No. 2009 / 02223514 A1.

[0066] The humidifier 15 comprises a humidifier chamber 16 and a lid 18 pivotally connected to the humidifier chamber 16. As shown in Figure 6, the lid 18 comprises a hinge portion 17 which is hinged to a hinge portion 47 provided on the humidifier chamber 16. As described in WO 2010 / 031126, an opening member 28 is provided for releasing the lid 18 and pivoting it to the open position shown in Figures 4 and 6.

[0067] Referring to FIG. 7 , the humidifier includes a tubing connector 70 and a tubing electrical connector 75. The tubing connector 70 and the tubing electrical connector 75 allow for connection of both standard and heated tubing. As shown in FIG. 7 , the tubing electrical connector 75 includes a plurality of contacts 78. Although three contacts 78 are shown, any number of contacts 78 (e.g., two, four, five, etc.) may be included in the plurality of contacts 78. The tubing electrical connector 75 and the contacts 78 are provided separately from the tubing connector 70. Heated tubing with corresponding electrical connections, such as terminals, may be provided with a rotating snap that fits with the tubing electrical connector 75, as described in more detail below. This type of connection facilitates connection and reduces the tolerance stack of the PAP system 10. A cover 132 may be connected to the rear wall of the humidifier 15 to cover the tubing connector 75 and the contacts 78 when unheated tubing is connected to the tubing connector 70. The cover 132 may be formed of flexible rubber or other suitable flexible material. Alternatively, the cover 132 may be a separate piece that is not attached to the humidifier and may be inserted over the tubing electrical connector 75 .

[0068] [Heated tube / conduit]

[0069] Figure 8 illustrates one embodiment of a heated air delivery conduit or tube. The heated tube 320 includes a flexible tube 325, a first connector or cuff 330(1) at one end of the tube 325 configured and arranged to engage the tube connector 70 and the tube electrical connector of the humidifier 15, and a second cuff 330(2) at the other end of the tube 325 configured and arranged to engage an inlet (e.g., a swivel elbow) of the patient interface 50, as shown in Figure 15. The heated tube 320 may be, for example, as disclosed in U.S. Patent Application Publication No. 2010 / 0116272 A1.

[0070] The tube 320 is structured to conduct heat along at least a portion of its length. For example, the helical rib 328 of the tube 325 can be structured to support the three wires 504, 506, 508 (FIGS. 15 and 18). Additionally, the heated tube 320 can be structured to support one or more sensing devices, such as a flow sensor and / or a temperature sensor. Further details of such tubing are disclosed in U.S. Patent Application Publication No. 2008 / 0105257 A1.

[0071] In the illustrated embodiment, cuffs 330(1), 330(2) are distinct from one another, as described below, although each cuff provides structure for attaching, sealing, and retaining the cuff to its respective connector (e.g., a 22 mm ISO tapered connector).

[0072] The opening of cuff 330(1) includes a radial lid seal, or sealing lid 331, along its inner surface. As shown in FIG. 13, radial sealing lid 331 provides an inner diameter d1 that is smaller than the outer diameter of tubing connector 70 in its relaxed, undeformed configuration. For example, the inner diameter may be less than about 22 mm (e.g., about 19-21 mm or less) for use with a standard 22 mm connector. In use, as best shown in FIG. 14, sealing lid 331 is configured to resiliently deform upon engagement with tubing connector 70 to provide an airtight seal against the outer surface of tubing connector 70. For example, sealing lid 331 provides a flexible protrusion configured to resiliently deflect within notch 335 from a first position (FIG. 13) to a second position (FIG. 14).

[0073] As shown, the sealing lid 331 tapers outward toward the cuff opening to provide sufficient lead-in for aligning and engaging the cuff 330(1) with the tubing connector 70.

[0074] An inner surface 333 axially inward from sealing lid 331 provides an inner diameter approximately the same as the outer diameter of tubing connector 70, e.g., approximately 22 mm for use with a standard 22 mm connector. A stop or flange-like surface 336 in cuff 330(1) provides a stop to prevent tubing connector 70 from extending further into cuff 330(1).

[0075] 9-14 depict a cuff 330(1) configured for attachment to a humidifier 15. The cuff 330(1) includes an electrical connector 60 configured to provide an electrical connection with the humidifier 15 for powering the heating wires 504, 506, 508 (FIG. 15) on the tubing 320. The electrical connector 60 includes terminals 62 configured to receive contacts 78 on the tubing electrical connector 75 of the humidifier 15 when the cuff 330(1) is connected to the tubing connector 70 of the humidifier 15. The electrical connector 60 provides a retention feature for the cuff 330(1). Retention is achieved by a rotational lock mechanism to mate the terminals 62 on the electrical connector 60 with the contacts 78 on the tubing electrical connector 75 of the humidifier 15. The electrical connector 60 provides a heel portion 64 configured to rotate into engagement with the tubing electrical connector 75, such that the heel portion 64 locks into a cam or recess on the tubing electrical connector 75 of the humidifier 15. When engaged, the heel portion 64 axially locks the cuff 330(1). To release, the cuff 330(1) is rotated out of engagement with the tubing electrical connector 75 and the heel portion 64 is removed. As shown in FIG. 13 , sealants 66 extend from the front, back, sides, and bottom of the electrical connector 60 and seal against the tubing electrical connector 75 of the humidifier 15 to protect the electrical contacts 78 and terminals 62 from water.

[0076] In the illustrated embodiment, the number of terminals 62 equals the number of contacts 78 (i.e., in the illustrated embodiment, there are three terminals 62). In other embodiments, the number of terminals 62 can vary to match the number of contacts 78 (e.g., the number of terminals 62 can be two, four, five, etc.). In still other embodiments, the number of terminals 62 and the number of contacts 78 can differ (e.g., there can be more or fewer terminals 62 than contacts 78).

[0077] S3 cuff 330(1) may include finger loops 340 along opposing sides and along the edge of electrical connector 60. Cuff 330(1) may also include an identification band 341 (e.g., an orange band) to identify the tube as a heated tube. A similar identification band may be provided on the user interface of PAP system 10 and may be configured to illuminate or otherwise signal when the heated tube is in an operating state, such as heating, being heated, etc. S3 Additionally, markings and / or images 343 may be provided on cuff 330(1) to indicate the direction of locking and unlocking cuff 330(1) relative to humidifier 15.

[0078] 15-18, a cuff 330(2) at the opposite end of the heated tube 320 is configured to attach to a patient interface (e.g., a mask) 50. The cuff 330(2) includes a sensor 45 located (e.g., molded) within the rear of the cuff. The cuff 330(2) includes a curved inlet surface 35, a sealing retention bead 37, and a restraining surface 39 to aid in connecting the heated tube 320 to the patient interface 50.

[0079] The sensor 45 is mounted on a fixture 46 within the cuff. In the illustrated embodiment, the fixture 46 is wing-shaped (e.g., airfoil-shaped) to optimize convective heat transfer over a range of flow rates while minimizing noise or pressure drop. However, the fixture 46 may have other suitable shapes and / or textures. The cuff 330(2) may be formed, for example, by overmolding onto a pre-block 49 or by any of the methods disclosed in U.S. Patent Application Publication No. 2008 / 0105257 A1, which is incorporated herein by reference in its entirety. The sensor 45 may be connected to wires 504, 506, and 508 within the heated tube 320 by a lead frame 48. The temperature sensed by the sensor 45 may be provided as a signal from the intermediate wire 504 through the lead frame 48 to the humidifier 15 and / or a controller in the PAP system 10.

[0080] As shown in FIG. 18 , the sensor 45 may take the form of a thermistor 410 formed of an NTC (negative temperature coefficient) material. The middle wire 504 of the three wires 504, 506, 508 of the tube circuit 402 may be connected to the thermistor 410 and may provide a temperature sensing signal to the controller. Two wires 506, 508 may be terminated at the lead frame 48 to complete the heating circuit. The third wire 504 provides a connection to an NTC thermistor that may be attached to a midpoint 507 of the heating circuit. The two heating wires 506, 508 may be low ohmic resistors to apply heat to the tube wall and, in turn, to the air being delivered to the patient. The signal wire 504 may be attached to the thermistor 410 at the patient-interface end of the heated tube 320. The signal wire 504 monitors the temperature of the air at the patient interface end of the heated tube and detects any imbalance between the bridge formed by the two heater wires 506, 508. This imbalance can be used to detect fault conditions, such as high impedance or an open circuit, and low impedance or a short circuit.

[0081] FIG. 20 is a schematic diagram of an alternative embodiment of the three-wire tube shown in FIG. 18. The three wires of heated tube circuit 402a are arranged as described in FIG. 18, except that middle wire 504a (wire 2, the sensing wire) is a different gauge than the two outer wires 506a, 508a (wires 1, 3, the heating wires). Any gauge of wire can be used; for example, heating wires 506a, 508a may have 31 AWG gauge, while sensing wire 504a may have 29 AWG gauge. Middle wire 504a is connected to thermistor 410a, which provides a temperature sensing signal to the controller. Middle wire 504a is also connected to heating wires 506a, 508a at midpoint 507.

[0082] 21 is a schematic diagram of an embodiment of a heated tube with a heated tube circuit 402b having four wires. In this embodiment, two wires 506b, 508b (wires 2, 3) are connected to form a heating circuit, and two wires 504b, 510b (wires 1, 4) are connected to form a sensing circuit that is separate from the heating circuit. Wires 1 and 4 504b, 510b may have a different gauge than wires 2 and 3 506b, 508b. While any gauge wires may be used, for example, wires 2 and 3 506b, 508b (heating wires) may have 31 AWG gauge, while wires 1 and 4 504b, 510b (sensing wires) may have 29 AWG gauge. Wires 1 and 4 504b, 510b are connected through a thermistor 410b, which provides a temperature sensing signal to the controller.

[0083] Heated tube embodiments utilizing wires of different gauges (e.g., as described with reference to FIGS. 20 and 21 ) may offer several advantages in both clinical utility and manufacturability. For example, the use of thinner gauge wires increases the overall flexibility of the tube and reduces its overall weight compared to tubes of similar construction but with the same gauge of wire in each tube. This increased flexibility and reduced weight have clinical benefits for patients, as they can benefit from increased comfort during treatment. Additionally, the use of thinner gauge wires with lower current carrying requirements (e.g., dedicated sensing wires) reduces the cost of manufacturing the tubes by reducing the amount of metal in each tube.

[0084] [Control of heated tubes]

[0085] The heated tube 320 can be used to provide the comfort of humidified warm air and minimize condensation within the tubing. Referring to FIG. 19, an algorithm for controlling the heated tube is shown. The algorithm begins in S300 and determines the temperature sensed by a temperature sensor (e.g., thermistor 410) within the heated tube in S302. The algorithm proceeds to S306, where it determines whether the sensed temperature is outside a predetermined range. If the heated tube temperature is not outside the predetermined range (No in S306), the algorithm terminates in S316. Conversely, if the temperature is outside the predetermined range (Yes in S306), the algorithm proceeds to S310, where it determines whether the temperature is above the predetermined range. If the temperature is below the predetermined range (No in S310), the algorithm proceeds to S312, where power is supplied to the heated tube. If the sensed temperature is above the predetermined range (Yes in S310), the algorithm proceeds to S314, where it shuts off power to the heated tube. After completion of S312 or S314, the algorithm loops back to the beginning at S300 to provide temperature control of the heated tube.

[0086] Controlling the heated tubes can have several considerations. One consideration is measuring and controlling the temperature of the air delivered within the heated tube system using a low-cost tube assembly. Another consideration is that, for safety, a fail-safe mechanism can be provided to ensure that the temperature of the delivered air does not exceed safe temperature limits. Yet another consideration is that it may be desirable to automatically identify whether the heated tubes attached to the humidifier and / or flow generator have a 15mm or 19mm inner diameter. The pneumatic performance of the system may require compensation in the blower drive circuit depending on which inner diameter tube is present.

[0087] Another consideration is that for safety purposes it is desirable to detect faults in the heated tube, such as high resistance hot spots in the wires, wire-to-wire shorts midway through the length of tubing, etc. A further consideration is that the heated tube can be electrically and pneumatically connected to the humidifier with simple installation procedures.

[0088] Current heated tube systems are implemented as open-loop control of the tube heating using a constant power level without directly regulating the temperature of the delivered air. While it may be possible to implement thermal fuses within the tube structure, these devices are relatively large and require additional circuit connections and mechanical mounting, significantly complicating the tube.

[0089] Heated Tube Control - Temperature Sensing with Active Overheat Protection

[0090] Referring to FIG. 22, an exemplary embodiment of circuitry 400 allows for control of tube air temperature using a sensor at the output (mask) end of the tube. Heated tube circuit 402 includes three wires 504, 506, and 508 and a temperature sensor, such as an NTC thermistor 410, located within the heated tube. Wires 404, 406, and 408 are used in a sensing and control circuit to achieve a low-cost heating and sensing system using only three wires, and are connected to the three wires 504, 506, and 508, respectively. As shown in FIG. 18, the three wires 504, 506, and 508 of heated tube circuit 402 are connected to various components of the sensing and control circuit, providing sensing wires 404, 504, power wire 406, and ground wire 408. In another embodiment of FIG. 22, three wires 504a, 506a, and 508a of heated tube circuit 402a of FIG. 20 or four wires 504b, 506b, 508b, and 510b of heated tube circuit 402b of FIG. 21 may be used in place of heated tube circuit 402 of FIG. 18. The sensing and control circuitry may be provided within the power supply and controller of the humidifier and / or flow generator. Such a power supply and controller is disclosed, for example, in U.S. Patent Application Publication No. 2008 / 0105257 A1. The complete sensing wire is formed by wires 404 and 504.

[0091] Referring again to FIG. 22, circuit configuration 400 includes a power supply 440, such as a 24V supply voltage, an over-temperature control circuit, and a heating control circuit. The over-temperature control circuit includes a first transistor switch 420 that turns on when the temperature of the heated tube falls below a predetermined temperature and turns off when the temperature exceeds the predetermined temperature. The predetermined temperature is set to a temperature that meets appropriate safety requirements for the heated tube, such as between 30°C and 45°C, preferably 38°C to 43°C. A comparator 436 controls the switching of transistor switch 420. A reference voltage representing the predetermined temperature is compared to the voltage determined from amplifier 430 of the sensing circuit to prevent the heated tube from exceeding the predetermined temperature.

[0092] Within the heat control circuit is a heating control circuit designed to control the heating of the heated tube to obtain a desired temperature. The desired temperature can be set by the user or determined by the system. The heating control circuit switches the power supply 440 to a ground reference 412 through the heated tube circuit 402. As a result, the temperature sensor 410 moves between 0 V and a ground that has half the power supply voltage, e.g., 12 V. Heating is provided from the power supply 440 to the heated tube circuit 402 through a second transistor switch 434. The transistor switch 434 opens and closes to turn the heating on and off, respectively, to the heated tube circuit 402. In one embodiment, the transistor switch 434 switches on and off very rapidly with a varying duty cycle to control the heating of the tube. However, the switch 434 can switch on to provide constant heating until the set temperature is reached, and then switch off. The heated tube temperature is sensed by temperature sensor 410 and transmitted through sense wires 404, 504 to sense resistor 426 and sensing circuit 428 with amplifier 430. Bias generation circuit 418 provides bias supply voltage Vcc to sensing circuit 428 so that the heated tube temperature can be determined regardless of whether the heated tube is heated. Bias generation circuit 418 generates a reference voltage. This reference voltage is Vcc bias supply voltage 414 (shown as 5V in this embodiment, although other voltages can be used) when tube heating is turned off via switch 422, and is half the supply voltage plus Vcc bias supply voltage 416, i.e., 5V, when tube heating is turned on via switch 424. Therefore, a constant Vcc bias supply voltage is provided to sensing circuit 428 regardless of the state of the heated tube. The switching of the bias switches 422, 424 is controlled by a transistor switch 434 in the heating control circuit, such that when the transistor switch 434 is closed the tube heating ON switch 424 is activated, and when the transistor switch 434 is open the tube heating ON switch 424 is deactivated, and so it is this voltage that is supplied to the heated tube circuit 402 that provides the bias switch.

[0093] The sensed temperature signal from temperature sensor 410 is provided to amplifier 430, which produces a voltage representative of the heated tube temperature. Temperature control block 432 controls the opening and closing of switch 434 to modulate the power sent to the heated tube circuit to maintain the desired temperature.

[0094] The temperature sensor 410 is held at different circuit potentials when the heater is activated and when it is not. However, to provide a fail-safe against overheating, the sensor 410 needs to be continuously monitored. For continuous sensing, a bias circuit 418 may be provided. A bias generation circuit supplies a supply voltage to the sensing circuit, which is a voltage divider network comprising resistor R1 and an NTC thermistor. This allows continuous temperature monitoring whether the sensing and control system is in a heating or idle state, facilitating active overheat detection that does not rely on a temperature control loop; temperature sensing remains active even during an overheating condition.

[0095] This circuit configuration may include a common ground referenced heating / sensing system that switches the supply voltage to the tube circuit for heating control. An alternative approach is to use the supply voltage as the power supply voltage for both heating and sensing, and control heating by switching the tube circuit to 0V.

[0096] Alternative Bias Generator Arrangements

[0097] As described above, the bias generator allows a three-wire or four-wire heated tube system to provide temperature sensing during an active heating cycle, or ON cycle, of the heating circuit and an inactive heating cycle, or OFF cycle, of the heating circuit. The temperature sensing remains active for at least a portion of the active (ON) heating cycle and the inactive (OFF) heating cycle, such as 50% or more, 75% or more, 90% or more, or 100%. Thus, the temperature sensing circuit can provide temperature sensing continuously while the heated tube is in use, regardless of the heating state of the system.

[0098] The heated tube circuits (e.g., 402, 402a, 402b) can be used in alternative bias generator arrangements, such as those described in Figures 20A-22 and 27 of U.S. Pat. No. 9,572,949 B2 and the accompanying description. [Explanation of symbols]

[0099] 20 Air Delivery Conduit 26 Electrical Connectors 46 Fixtures 325 tube 330(1), 330(2) Cuff 410 thermistor and 504, 506, 508 Wires

Claims

1. 1. An air delivery conduit for use in an apparatus for delivering a supply of pressurized breathing air to a patient, comprising: a tube having a first end and a second end; a first wire extending at least partially between the first end and the second end, the first wire having a first diameter; a second wire extending at least partially between the first end and the second end, the second wire having a second diameter different from the first diameter; a first cuff coupled to the first end of the tube and including an electrical connector connected to the first wire and the second wire to provide an electrical connection with the device; a second cuff coupled to the second end of the tube, a thermistor connected to the first wire; a fixture projecting from an interior surface of the second cuff into a flow path of the supply of pressurized breathable air through the second cuff, the fixture housing the thermistor; a second cuff comprising: an air delivery conduit comprising:

2. The air delivery conduit of claim 1 , wherein the tube has a helical rib, and the first wire and the second wire are positioned within the helical rib.

3. 3. The air delivery conduit of claim 1, wherein the electrical connector includes a first terminal corresponding to the first wire and a second terminal corresponding to the second wire, the first terminal and the second terminal configured to receive contacts of the device.

4. The second cuff comprises: a first end having the inner surface secured to the outer surface of the tube; a second end including an elastomeric material for frictionally engaging an outer surface of the tubular connector; 4. The air delivery conduit of claim 1, further comprising:

5. 5. The air delivery conduit of claim 1, wherein the first wire and the second wire are electrically connected to each other.

6. 6. An air delivery conduit according to any one of claims 1 to 5, wherein the second wire is a heating wire and is made of a low ohmic resistor for applying heat to the tube.

7. 7. The air delivery conduit of claim 1, further comprising a third wire extending at least partially between the first end and the second end, the third wire having a third diameter different from the first diameter.

8. 8. The air delivery conduit of claim 7, wherein the third wire is a heating wire and is made of a low ohmic resistor for applying heat to the tube.

9. 9. The air delivery conduit of claim 7 or 8, wherein the third wire is electrically connected to the second wire.

10. 10. An air delivery conduit according to any one of claims 7 to 9, wherein the third wire is electrically connected to the first wire.

11. 11. An air delivery conduit according to any one of claims 7 to 10, wherein the third wire is connected to ground.

12. 12. The air delivery conduit of claim 7, wherein the first wire monitors the temperature of the air adjacent to the second cuff and detects an imbalance between a bridge formed by the second wire and the third wire.

13. 13. An air delivery conduit according to any one of claims 7 to 12, wherein the third diameter is equal to the second diameter.

14. 14. The air delivery conduit of claim 1, further comprising a fourth wire extending at least partially between the first end and the second end, the fourth wire having a fourth diameter different from the second diameter.

15. 15. The air delivery conduit of claim 14, wherein the fourth wire is a sensing wire and is electrically connected to the thermistor and the first wire.

16. 16. An air delivery conduit according to any one of claims 14 to 15, wherein the fourth wire is included in a circuit separate from the first wire.

17. 17. An air delivery conduit according to any one of claims 14 to 16, wherein the fourth wire is connected to ground.

18. 18. An air delivery conduit according to any one of claims 14 to 17, wherein the fourth diameter is equal to the first diameter.

19. 19. The air delivery conduit of any one of claims 1 to 18, wherein the second diameter is greater than the first diameter.

20. 20. The air delivery conduit of claim 1, wherein the first diameter corresponds to 29 gauge American Wire Gauge (AWG).

21. 21. The air delivery conduit of claim 1, wherein the second diameter corresponds to 31 gauge AWG.

22. 22. The air delivery conduit of claim 1, wherein the tube, the first wire, and the second wire are flexible, and the first diameter increases the overall flexibility of the tube compared to the second diameter.

23. 1. An air delivery conduit for use in an apparatus for delivering a supply of pressurized breathing air to a patient, comprising: a tube having a first end and a second end; a first wire extending at least partially between the first end and the second end, the first wire having a first diameter; a second wire extending at least partially between the first end and the second end, the second wire having a second diameter different from the first diameter; a third wire extending at least partially between the first end and the second end, the third wire having a third diameter different from the first diameter; a first cuff coupled to the first end of the tube and including an electrical connector connected to the first wire and the second wire to provide an electrical connection with the device; a second cuff coupled to the second end of the tube, the second cuff including a thermistor connected to the first wire; an air delivery conduit comprising:

24. 24. The air delivery conduit of claim 23, comprising a fixture projecting from an inner surface of the second cuff into a flow path of the supply of pressurized breathable air flowing through the second cuff, the fixture housing the thermistor.

25. 25. The air delivery conduit of claim 23 or 24, wherein the tube has a helical rib and the first wire, the second wire, and the third wire are positioned within the helical rib.

26. 26. The air delivery conduit of any one of claims 23 to 25, wherein the electrical connector includes a first terminal corresponding to the first wire, a second terminal corresponding to the second wire, and a third terminal corresponding to the third wire, the first terminal, the second terminal, and the third terminal configured to receive contacts of the device.

27. 27. The air delivery conduit of any one of claims 23 to 26, wherein the first wire, the second wire, and the third wire are electrically connected to one another.

28. 28. An air delivery conduit according to any one of claims 23 to 27, wherein the second wire and the third wire are heating wires and are made of low ohmic resistors for applying heat to the tube.

29. 29. An air delivery conduit according to any one of claims 23 to 28, wherein the third wire is connected to ground.

30. 30. The air delivery conduit of any one of claims 23 to 29, wherein the first wire monitors the temperature of air adjacent the second cuff and detects an imbalance between a bridge formed by the second wire and the third wire.

31. 31. An air delivery conduit according to any one of claims 23 to 30, wherein the third diameter is equal to the second diameter.

32. 32. An air delivery conduit according to any one of claims 23 to 31, wherein the first diameter corresponds to 29 gauge American Wire Gauge (AWG).

33. 33. An air delivery conduit according to any one of claims 23 to 32, wherein the second diameter corresponds to AWG 31 gauge.

34. 1. An air delivery conduit for use in an apparatus for delivering a supply of pressurized breathing air to a patient, comprising: a tube having a first end and a second end; a first wire extending at least partially between the first end and the second end, the first wire having a first diameter; a second wire extending at least partially between the first end and the second end, the second wire having a second diameter different from the first diameter; a third wire extending at least partially between the first end and the second end, the third wire having a third diameter different from the first diameter; a fourth wire extending at least partially between the first end and the second end, the fourth wire having a fourth diameter different from the second diameter; a thermistor connected to the first wire; a fixture projecting from an interior surface of the tube into the flow path of the supply of pressurized breathing air passing through the tube, the fixture housing the thermistor; an air delivery conduit comprising:

35. 35. The air delivery conduit of claim 34, further comprising a cuff coupled to said second end, said cuff including said inner surface, and said fastener protruding from said cuff.

36. 36. An air delivery conduit according to any one of claims 34 to 35, wherein the first wire and the fourth wire form a sensing circuit and the second wire and the third wire form a heating circuit separate from the sensing circuit.

37. 37. An air delivery conduit according to any one of claims 34 to 36, wherein the third wire and the fourth wire are connected to ground.

38. 38. An air delivery conduit according to any one of claims 34 to 37, wherein the first diameter is equal to the fourth diameter.

39. 39. An air delivery conduit according to any one of claims 34 to 38, wherein the second diameter is equal to the third diameter.

40. 40. An air delivery conduit according to any one of claims 34 to 39, wherein the first diameter corresponds to 29 gauge American Wire Gauge (AWG).

41. 41. An air delivery conduit according to any one of claims 34 to 40, wherein the second diameter corresponds to 31 gauge AWG.

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