Patent Publication Number: US-2020289783-A1

Title: Usability features for respiratory humidification system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority benefit of U.S. Provisional Application No. 61/992,442, filed May 13, 2014, U.S. Provisional Application No. 62/032,208, filed Aug. 1, 2014, and U.S. Provisional Application No. 62/127,443, filed Mar. 3, 2015, each of which is hereby incorporated by reference herein. The following provisional applications are hereby incorporated by reference in their entirety: U.S. Provisional Application No. 61/919,485, filed Dec. 20, 2013; U.S. Provisional Application No. 61/893,758, filed Oct. 21, 2013; U.S. Provisional Application No. 61/877,566, filed Sep. 13, 2013; U.S. Provisional Application No. 61/877,784, filed Sep. 13, 2013; U.S. Provisional Application No. 62/024,969, filed Jul. 15, 2014; and U.S. Provisional Application No. 62/032,462, filed Aug. 1, 2014. 
    
    
     BACKGROUND 
     Field of the Disclosure 
     The present disclosure generally relates to humidification systems for humidifying gases supplied to users, and more particularly, to humidification systems having features for improved assembly and usability. 
     Description of the Related Art 
     Many gas humidification systems deliver heated and humidified gases for various medical procedures, including respiratory treatment, laparoscopy, and the like. These systems can be configured to control temperature, humidity, and flow rates through the use of various sensors. 
     Various components of such systems also can include features designed to help control the system and/or help provide users with gases having desired characteristics. Such gas humidification systems can include many components that must be assembled prior to use. The set-up process can be complicated and time-consuming, and may require specialized training. The specialized training may need to be repeated for each new employee or user. Thus, there is a need for a system that is intuitive to assemble and use without extensive training. 
     Circuits for use in medical systems often comprise a cap to aid with storage and to protect against ingress of dust or contaminants. However, prior art caps comprise materials that may cause damage to an internal surface of the circuit. Caps can fall off in storage or leak. Caps can be challenging for a user to insert and to remove, requiring high forces to insert and/or remove. 
     Caps often remain connected with the circuit as a user sets up the medical system. For example, in a respiratory system, the cap remains connected with the circuit until the patient interface is connected to the circuit. A user may activate a gases source while the cap remains in place on the circuit. As a result, pressure building up in the circuit can cause the cap to fail. Failure is measured, for example, by the cap coming off the circuit, or by damage to circuit components caused by pressure increases. 
     Circuits are often bulky and difficult to manipulate in use. A user setting up the system in advance may attempt to drape the circuit across other components in the system in an effort to keep the circuit from being contaminated, for example, by touching the floor. The circuit can be prone to falling to the floor and becoming contaminated. 
     SUMMARY 
     A humidification system for delivering humidified gases to a user can comprise a heater base, a humidification chamber having an inlet, outlet, and associated liquid conduit, and a breathing circuit including a supply conduit, inspiratory conduit, and optional expiratory conduit. A humidification system can comprise various features as described herein to help make set-up less difficult and time-consuming. Such features can also help make the set-up process more intuitive for an operator, which can reduce the need for specialized training and reduce the number of potential errors. 
     According to some aspects of the present disclosure, a humidification apparatus comprises a humidification chamber configured to hold a volume of liquid. The humidification chamber comprises at least one side wall, a top wall connected to the at least one side wall, a cavity at least partially defined by the at least one side wall and the top wall, an inlet port defining a passage into the cavity of the humidification chamber, an outlet port defining a passage out of the cavity of the humidification chamber and having an elbow configuration, wherein the outlet port is uncovered for shipping and/or storage, and a port cap configured to cover the inlet port for shipping and/or storage, the port cap comprising a leg that extends into the inlet port. 
     The inlet port can comprise a baffle extending at least partially below the inlet port and configured to inhibit splashing through the inlet port, wherein the leg of the port cap is configured to extend below the baffle. The leg of the port cap can be configured to secure one or more floats within the humidification chamber for shipping and/or storage. The chamber can further comprise a liquid inlet in fluid communication with the cavity and a liquid conduit having a first end coupled to the liquid inlet and a second end coupled to a spike configured to be connected to a liquid source, wherein the spike is positioned under the port cap for shipping and/or storage. The liquid conduit can be looped and inserted under the port cap during assembly for shipping and/or storage. The chamber can further comprise a liquid inlet in fluid communication with the cavity and a liquid conduit having a first end coupled to the liquid inlet and a second end coupled to a spike configured to be connected to a liquid source, wherein the spike is stored in a sheath attached to the port cap for shipping and/or storage. 
     The chamber can further comprise a handle coupled to the chamber, a shelf extending between a portion of the handle and a portion of the at least one side wall of the chamber, a liquid inlet in fluid communication with the cavity, and a liquid conduit having a first end coupled to the liquid inlet and a second end coupled to a spike configured to be connected to a liquid source, wherein the spike is stored on the shelf for shipping and/or storage. The liquid conduit can be stored on the shelf for shipping and/or storage. The port cap can comprise a ring configured to be grasped for removal of the port cap and to be attached to a medical stand. The humidification apparatus can further comprise an inspiratory conduit having a first end coupled to the outlet port for shipping and/or storage. The port cap can comprise a contact surface, and a heater base configured to support the humidification chamber can comprise a lifting surface, so that when the humidification chamber is inserted onto the heater base with the port cap covering the inlet port, the lifting surface contacts the contact surface and causes the port cap to lift away from the inlet port. The lifting surface can be on a sensor cartridge module coupled to the heater base. 
     According to some aspects of the present disclosure, a circuit end cap comprises a body configured to be inserted into an end of a breathing circuit component, a flange at a first end of the body, wherein a diameter of the flange is larger than a diameter of the body and a lower surface of the flange configured to face the body is configured to seal against the end of the breathing circuit component, and a pull ring extending from the body and configured to be used to aid removal of the circuit end cap from the breathing circuit component and/or to hang the breathing circuit component from a medical stand or hook. 
     The body can comprise frustoconical tapers configured to form a sealing interface with an interior of the breathing circuit component. The body can comprise three frustoconical tapers such that the frustoconical tapers provide a sufficient friction fit with the breathing circuit component while allowing the circuit end cap to be removed from the breathing circuit component without excessive force. The pull ring can extend from a top surface of the flange along a longitudinal axis of the body. Alternatively, the pull ring can extend from a side of the flange perpendicularly to a longitudinal axis of the body. A diameter of the flange can be selected for use with various breathing circuit components. The diameter of the body and frustoconical tapers can be selected for use with various breathing circuit components. The body can comprise a plurality of channels, each channel extending parallel to a longitudinal axis of the body on an outside surface of the body, wherein the channels allow gases to vent from the breathing circuit component. The plurality of channels can extend into the lower surface of the flange. The body can comprises a plurality of channels extending parallel to a longitudinal axis of the body on an outside surface of the body, wherein the channels separate the frustoconical tapers into a plurality of segments. 
     According to some aspects of the present disclosure, a humidification chamber is packaged with the inlet port and the outlet port covered by a port cap. The port cap can be designed to help indicate to the operator that the port cap should be removed and discarded during set-up. A liquid conduit, or feedset, can be contained and concealed by the port cap so that the feedset cannot be connected to a liquid source until the port cap is removed. The port cap can be designed to cover only the inlet port or only the outlet port. 
     According to some aspects of the present disclosure, a supply conduit, an inspiratory conduit, and an optional expiratory conduit are coupled into a one-piece assembly to aid set-up. The conduits can be coupled by, for example, a mesh sheath, clips, or any other appropriate coupling mechanism. One or more of the conduits can be removably coupled to the others. The expiratory conduit can include an electrical plug configured to be connected to a socket on the heater base to power a heating element within the conduit. One or more of the conduits can include integrated sensors and adaptor cables to connect the sensors to the heater base. 
     According to some aspects of the present disclosure, various components of a humidification system are color-coded and can have corresponding structures to indicate which components should be connected to one another during set-up. The heater base and/or consumables packaging can also include a schematic or step-by-step instructions to help guide the operator through the set-up procedure. 
     According to some aspects of the present disclosure, a humidification apparatus comprises a heater base and a humidification chamber. The heater base comprises a heater and a display, the heater plate being configured to support a humidification chamber and the display oriented at an angle of about 22° from vertical. The humidification chamber can be configured to hold a volume of liquid and can comprise at least one side wall, a top wall connected to the at least one side wall, a base surface connected to the at least one side wall, a cavity being at least partially defined by the at least one side wall and the top wall, at least one of the at least one side wall and the top wall of the humidification chamber having features that define a front of the humidification chamber and a back of the humidification chamber, a liquid inlet in fluid communication with the cavity, the liquid inlet positioned closer to the front of the humidification chamber than the back of the humidification chamber, an inlet port defining a passage into the cavity of the humidification chamber, an outlet port defining a passage out of the cavity of the humidification chamber, wherein the outlet port has an elbow shape, and a liquid conduit having a first end coupled to the liquid inlet and a second end configured to be connected to a liquid source. The liquid conduit can comprise a first end coupled to the liquid inlet and a second end coupled to a spike configured to be connected to a liquid source. 
     According to some aspects of the present disclosure, a humidification apparatus comprises a heater base, a humidification chamber, and a liquid conduit. The heater base comprises first and second sensors and a heater plate, the first and second sensors being positioned vertically higher than the heater plate, the heater plate being configured to support a humidification chamber. The humidification chamber can be configured to hold a volume of liquid and can comprise at least one side wall, a top wall connected to the at least one side wall, a cavity being at least partially defined by the at least one side wall and the top wall, a liquid inlet in fluid communication with the cavity, an inlet port extending through the top wall and defining a passage into the cavity, the inlet port having an aperture configured to receive the first sensor, an outlet port extending through the top wall and defining a passage out of the cavity, the outlet port having an aperture configured to receive the second sensor, and interlock features in the top wall configured to receive corresponding interlock features on the heater base to guide insertion of the chamber on the heater base so that the first and second sensors are received in the apertures of the inlet and outlet ports. The first and second sensors can be integrated into a sensor cartridge module that is mechanically and electrically connected to the heater base. 
     The humidification apparatus can further comprise a supply conduit and an inspiratory conduit, wherein a first end of the supply conduit comprises a chamber end connector configured to be coupled to the inlet port, a second end of the supply conduit is configured to be coupled to a gases supply, at least part of the inlet port comprises a first indicator, at least part of the supply conduit chamber end connector comprises the first indicator, a first end of the inspiratory conduit comprises a chamber end connector configured to be coupled to the outlet port, at least part of the outlet port comprises a second indicator, and at least part of the inspiratory conduit chamber end connector comprises the second indicator. The first indicator can comprise a first color, and the second indicator can comprise a second color. 
     The interlock features in the top wall can comprise a recess and the interlock features on the heater base can comprise a protrusion, the recess configured to receive the protrusion, and the protrusion configured to extend greater than halfway across the chamber when the chamber is fully installed on the heater base. The interlock features in the top wall can further comprise a raised portion and the interlock features on the heater base can further comprise a central channel located on a bottom surface of the protrusion, the raised portion configured to be received in the central channel when the chamber is properly installed on the heater base. The humidification apparatus can further comprise a port cap configured to cover the inlet port for shipping and/or storage, the port cap comprising a leg that extends into the inlet port. The port cap can be configured to cover the spike for shipping and/or storage. The heater base can further comprise a guard along a front portion of a rim edge, the guard configured to be depressed to enable a lower portion of the chamber to slide under the rim edge and the guard configured to revert to a non-depressed position once the chamber is installed on the heater base. 
     According to some aspects of the present disclosure, a humidification apparatus comprises a humidification chamber configured to hold a volume of liquid and comprising at least one side wall, a top wall connected to the at least one side wall, a base surface connected to the at least one side wall, a cavity at least partially defined by the at least one side wall and the top wall, at least one of the at least one side wall and the top wall of the humidification chamber having features that define a front of the humidification chamber and a back of the humidification chamber, an inlet port defining a passage into the cavity of the humidification chamber, the inlet port having an aperture configured to receive a first sensor mounted on a heater base, and an outlet port defining a passage out of the cavity of the humidification chamber and having an aperture configured to receive a second sensor mounted on the heater base, wherein an axis extending through the aperture of the inlet port is generally parallel to an axis extending through the aperture of the outlet port, the axes extending in a front to back direction of the humidification chamber and the axes extending generally parallel to the base surface of the humidification chamber. 
     The humidification apparatus can further comprise a heater base configured to receive the humidification chamber. At least one of the at least one side wall and the top wall can comprise interlock features configured to receive corresponding interlock features on the heater base to guide insertion of the chamber on the heater base so that the first and second sensors are received in the apertures of the inlet and outlet ports. The interlock features can comprise recesses in the top wall and the interlock features on the heater base comprise corresponding protrusions, the interlock features of the top wall and the interlock features on the heater base being engaged through movement along the axes of the apertures in the inlet port and the outlet port. In some embodiments, the heater base comprises a sensor cartridge comprising the first and second sensors. The humidification apparatus can further comprise an inspiratory conduit comprising a chamber end connector configured to be coupled to the outlet port and at least one sensor and/or heating element, the chamber end connector comprising an electrical connection configured to couple to a corresponding electrical connection on the sensor cartridge. 
     The humidification apparatus can comprise a supply conduit, an inspiratory conduit, and an expiratory conduit, wherein a first end of the supply conduit is configured to be coupled to a gases supply, a second end of the supply conduit comprises a chamber end connector configured to be coupled to the inlet port, a first end of the inspiratory conduit comprises a chamber end connector configured to be coupled to the outlet port, a first end of the expiratory conduit is configured to receive gases exhaled by a patient in use, and a second end of the expiratory conduit is configured to be coupled to the gases supply. The supply conduit, the inspiratory conduit, and the expiratory conduit can be coupled to one another to form a one-piece circuit. The supply conduit, the inspiratory conduit, and the expiratory conduit can be coupled with, for example, a mesh wrap, clips, a hook and loop fastener, or a snap fit. 
     At least part of the chamber end connector of the supply conduit and at least part of the inlet port can comprise a first indicator. The first indicator can comprise a first color. At least part of the chamber end connector of the inspiratory conduit and at least part of the outlet port can comprise a second indicator. The second indicator can comprise a second color. The humidification apparatus can further comprise a Y-piece, wherein a second end of the inspiratory conduit comprises a patient end connector configured to be coupled to a first branch of the Y-piece, the first end of the expiratory conduit comprises a patient end connector configured to be coupled to a second branch of the Y-piece, and at least part of the Y-piece comprises a third indicator. The third indicator can comprise a third color. The supply conduit, the inspiratory conduit, and the expiratory conduit can be held in a looped configuration with a circuit sleeve for shipping and/or storage. The circuit sleeve can be positioned on the conduits to hide selected connectors to help guide sequential connection of the conduits. 
     The humidification apparatus can comprise a liquid inlet and a liquid conduit having a first end coupled to the liquid inlet and a second end coupled to a spike configured to be connected to a liquid source. The humidification apparatus can further comprise a winder, and the liquid conduit can extend from the liquid inlet, around the winder, and into the winder, and the spike can be seated in the winder for shipping and/or storage. The humidification apparatus can comprise a port cap configured to cover the inlet port and the outlet port for shipping and/or storage. The port cap can comprise legs that extend into the inlet port and the outlet port. The humidification apparatus can comprise a port cap configured to cover the inlet port for shipping and/or storage, the port cap comprising a leg that extends into the inlet port. The humidification apparatus can comprise a port cap configured to cover the outlet port for shipping and/or storage, the port cap comprising a leg that extends into the outlet port. The port cap can be configured to cover the spike for shipping and/or storage. 
     The humidification apparatus can include grips configured to allow an operator to hold the chamber more easily during installation. The grips can comprise recesses in the side wall of the chamber. The apertures can be positioned in the inlet and outlet ports so that the apertures face rearward and the grips are located in a front half of the chamber to help orient the chamber for installation on the heater base. The heater base can comprise a guard along a front portion of a rim edge, the guard configured to be depressed to enable a lower portion of the chamber to slide under the rim edge and the guard configured to revert to a non-depressed position once the chamber is installed on the heater base. 
     According to some aspects of the present disclosure, a cap for a medical circuit can comprise a coupling component and a plug connected to the coupling component. The plug may comprise a disc and a body. The disc may have a diameter that is larger than the diameter of the body. This aids in the at least partial sealing of the circuit. For example, the channels and the disc provide a tortuous path for dust or contaminant ingress into the circuit. The body may comprise at least one segment of at least one frustoconical taper to facilitate at least partial sealing between the cap and an end of a medical circuit. The body may further comprise a channel. The channel may be configured to provide a passageway for gases. If a user initiates gases flow in a circuit prior to removing the cap from the circuit, the gases can be released to the atmosphere through the channels. This release of gases reduces the pressure build up within the circuit. The body may comprise a cylindrical structure. The body may comprise a first end that is sealed by the disc and a second end that is branched by at least one rib or a pair of ribs. The ribs may be perpendicular to each other. The ribs may be attached to the disc and to an internal wall of the body. The disc may comprise a lip that extends perpendicularly from a perimeter of the disc. The channel may extend into the lip or into the disc. 
     The cap can comprise a material that reduces the likelihood of damage to internal surfaces of the end of the circuit. At least a portion of the body of the cap can configured to be at least partially received by a medical circuit. The channel can comprise at least one orifice. The at least one segment of the at least one frustoconical taper can comprise a total area that is at least 73% of the area of the outer surface of the body. The disc can comprise an upper surface that is configured to convey a visual message to a user. The message can be in the form of a drawing, instruction, colour coding, text, or a combination of these. The body can comprise a plurality of channels. The plurality of channels can comprise a total area that is no greater than 27% of the area of the outer surface of the body. The coupling component can be configured to facilitate hanging of the cap on a supporting structure. The coupling component can be configured to facilitate hanging the cap, coupled to a medical circuit, on a supporting structure. The coupling component can be configured to receive a finger. The coupling component can be configured to facilitate removal of the cap from the medical circuit. The coupling component can comprise a ring. 
     For purposes of summarizing the disclosure and the advantages achieved over the prior art, certain objects and advantages are described herein. It is to be understood that not necessarily all such objects or advantages need to be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught or suggested herein without necessarily achieving other objects or advantages as may be taught or suggested herein. All of these embodiments are intended to be within the scope of the disclosure herein. These and other embodiments will become readily apparent to those skilled in the art from the following detailed description having reference to the attached figures, the disclosure not being limited to any particular disclosed embodiment(s). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects and advantages of the present disclosure will be described with reference to the following drawings, which are illustrative but should not be limiting of the present disclosure. 
         FIG. 1  illustrates a schematic of a humidification system. 
         FIG. 2A  illustrates a humidification chamber installed on a heater base. 
         FIG. 2B  illustrates a humidification chamber. 
         FIG. 3  illustrates a heater base. 
         FIGS. 4A-4H  illustrate a humidification chamber as packaged. 
         FIG. 4I  illustrates a spike including a sheath. 
         FIG. 4J  illustrates the spike of  FIG. 4I  without the sheath. 
         FIGS. 4K-4L  illustrate a spike including a sheath. 
         FIG. 4M  illustrates the sheath of  FIGS. 4K-4L  removed from the spike. 
         FIG. 5A  illustrates a sensor cartridge and a humidification chamber. 
         FIG. 5B  illustrates a sensor cartridge coupled to a heater base. 
         FIG. 5C  illustrates a sensor cartridge connected to a heater base with an electrical cable. 
         FIG. 6  illustrates a humidification chamber. 
         FIG. 7A  illustrates breathing conduits as packaged. 
         FIG. 7B  illustrates a humidification chamber with features to promote proper connections. 
         FIG. 8  illustrates conduits having features corresponding to those shown in  FIG. 7B . 
         FIG. 9A  illustrates a one-piece circuit. 
         FIG. 9B  illustrates a releasable connection system for a one-piece circuit. 
         FIG. 10  illustrates a method for setting up a humidification system. 
         FIG. 11  illustrates a heater base and a humidification chamber. 
         FIG. 12  illustrates a chamber installed on a heater base having a sensor cartridge. 
         FIGS. 13A-13B  illustrate the chamber of  FIG. 12 . 
         FIGS. 14A-14F  illustrate various views of a port cap installed on the chamber of  FIGS. 12-13B . 
         FIGS. 14G-14H  illustrate a port cap. 
         FIGS. 141-14J  illustrate the port cap of  FIGS. 14G-14H  installed on the chamber of  FIGS. 12-13B . 
         FIGS. 14K-14P  illustrate a port cap installed on the chamber of  FIGS. 12-13B . 
         FIG. 15  illustrates the base having the sensor cartridge of  FIG. 12  with the chamber removed. 
         FIG. 16  illustrates a side view of an end cap for a Y-piece or conduit. 
         FIG. 17  illustrates a top perspective view of the end cap of  FIG. 19 . 
         FIGS. 18 and 19  illustrate the end cap of  FIGS. 16 and 17  coupled to a circuit component and hanging from a medical stand. 
         FIG. 20A  illustrates a perspective view of an alternative end cap. 
         FIG. 20B  illustrates the end cap of  FIG. 20A  coupled to a Y-piece. 
         FIG. 21A  illustrates a perspective view of an alternative end cap. 
         FIG. 21B  illustrates the end cap of  FIG. 21A  coupled to the Y-piece. 
         FIG. 22A  illustrates a perspective view of an alternative end cap. 
         FIG. 22B  illustrates the end cap of  FIG. 22A  coupled to the Y-piece. 
         FIG. 23A  illustrates a perspective view of an alternative end cap. 
         FIG. 23B  illustrates the end cap of  FIG. 23A  coupled to the Y-piece. 
         FIGS. 24A-24E  illustrate the end caps of  FIGS. 16, 20A, 21A, 22A, and 23A , respectively, coupled to an alternative Y-piece. 
         FIG. 25  illustrates a perspective view of a chamber assembly. 
         FIG. 26  illustrates a front elevation view of a chamber assembly. 
         FIG. 27  illustrates a front elevation view of a chamber assembly with a feedset attached. 
         FIG. 28  illustrates a side elevation view of a chamber assembly with the internal components shown. 
         FIG. 29  illustrates a front elevation view of a chamber assembly. 
         FIG. 30  illustrates an enlarged side perspective view of a chamber assembly showing a port cap being removed during insertion. 
         FIG. 31  illustrates another side elevation view of a chamber assembly with an alternative port cap. 
         FIG. 32  illustrates a perspective view of a chamber assembly with a feedset attached. 
         FIG. 33  illustrates a front elevation view of a chamber assembly. 
         FIG. 34  illustrates a side elevation view of a chamber assembly. 
         FIG. 35  illustrates a perspective view of a portion of a port cap. 
         FIGS. 36 and 37  illustrate perspective views of a portion of a port cap. 
         FIG. 38  illustrates a schematic of a medical system. 
         FIGS. 39A-39B  illustrate a perspective view of a cap. 
         FIG. 39C  illustrates a top view of a cap. 
         FIG. 39D  illustrates a bottom view of a cap. 
         FIG. 40  illustrates a perspective view of a cap. 
         FIG. 41A  illustrates a bottom view of a cap. 
         FIG. 41B  illustrates a top view of a cap. 
         FIG. 42A  illustrates a bottom view of a cap. 
         FIG. 42B  illustrates a top view of a cap. 
         FIGS. 43A-43B  illustrate perspective views of caps. 
     
    
    
     DETAILED DESCRIPTION 
     Although certain embodiments and examples are described below, those of skill in the art will appreciate that the disclosure extends beyond the specifically disclosed embodiments and/or uses and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the present disclosure should not be limited by any particular embodiments described below. 
     An example embodiment of a humidification system  100  can include a heater base  102 , a humidification chamber  104 , and a breathing circuit or breathing circuit assembly, for example, as shown in  FIG. 1 . In some embodiments, the system  100  further comprises a gases supply  130 , for example, a ventilator or other suitable source of pressurized gases suitable for breathing or use in medical procedures. The heater base  102  can include a heater plate  108  (better shown in  FIG. 3 ). In addition, the heater base  102  can comprise one or more processors  114  and one or more memories or other suitable storage components. In some embodiments, the heater base  102  also comprises a display that can provide information to and/or receive input from an operator. 
     In some configurations, the display can have a schematic to facilitate the operator making the desired connections, in some instances in a desired order. For example, the display can have a static image with lights (e.g., LED) under different regions that light in a sequence to encourage the desired connection order. In some configurations, the image can be formed on membranes that are back-screen printed behind a polyester or polycarbonate film with LEDs attached to or positioned adjacent to the film. In some configurations, the lights may begin the sequence when a switch is operated by insertion of a humidification chamber into the heater base or the like. Such configurations resolve any need for an operator to turn on the heater base to get the feedback on proper connection sequence. Other suitable arrangements also can be used. 
     The humidification chamber  104  generally comprises an inlet  110  and an outlet  112  and is configured to be installed on the heater plate  108  of the heater base  102 . The humidification chamber  104  is further configured to hold a volume of a liquid, such as water. The chamber  104  can include an opening or port for the connection of a liquid conduit or feedset  118 . The liquid conduit  118  can extend from the chamber  104 , as shown in  FIG. 2A . In some configurations, the liquid conduit  118  can connect to a spike for a water bag. In some configurations, the liquid conduit  118  can be integrally formed with or permanently coupled to the chamber  104 . The spike can be coupled to the liquid conduit  118  via an adhesive, sonic welding, an interference fit, or any other suitable means. In some embodiments, the spike includes a vent. If the spike is inserted into, for example, a plastic, collapsible bag, the vent is plugged. However, if the spike is inserted into a rigid container, such as a glass bottle, the vent is open and allows air to enter the container to help reduce or prevent negative pressures in the container. The vent can include a filter that is permeable to gases but impermeable to liquids. 
     In use, the liquid conduit  118  conveys a liquid, for example, water, from a liquid source, such as a water bag, saline bag, or the like, to the chamber  104 . The heater plate  108  heats the chamber  104  and causes at least some of the chamber  104  contents to evaporate. In some embodiments, the humidification chamber  104  can include features to help reduce the likelihood of the level of liquid in the chamber  104  from exceeding a particular level. For example, the chamber  104  can include one or more floats  150  as shown in  FIGS. 2B, 4A, and 4B . The floats rise and fall with the level of liquid in the chamber  104 . When the liquid level reaches a certain level, the floats  150  obstruct or block the port that is connected to the liquid conduit  118  to stop or slow further ingress of liquid into the chamber  104 . Other similar features also can be used. In a preferred embodiment, a plurality of floats  150  are used, each float adapted to stop the further ingress of liquid into the chamber  104 . To this end, a second float provides a backup or safety mechanism, thereby further reducing the likelihood of the chamber  104  overfilling.  FIG. 2B  illustrates an example embodiment of such a chamber  104  having a primary float  248   a  and a secondary float  248   b.    
     With reference again to  FIG. 1 , the breathing circuit assembly can include a supply conduit  120 , an inspiratory conduit  122 , and, in some configurations, an expiratory conduit  124 . A gases supply end of the supply conduit  120  is configured to connect to an output  132  of the gases supply  130  and a chamber end of the supply conduit  120  is configured to connect to the inlet  110  of the chamber  104 . A chamber end of the inspiratory conduit  122  is configured to connect to the outlet  112  of the chamber  104 , and a user end of the inspiratory conduit  122  is configured to connect to the user  128  via an interface  126 , for example. A user end of the expiratory conduit  124  is configured to connect to the interface  126 , and a gases supply end of the expiratory conduit  124  is configured to connect to a return  134  of the gases supply  130 . The user ends of the inspiratory conduit  112  and expiratory conduit  124  can be connected to the interface  126  via a Y-piece  127 , for example but without limitation. 
     In use, gases flow from the gases supply  130  through the supply conduit  120  and into the chamber  104  via the inlet  110 . The gases are humidified within the chamber  104  and exit the chamber  104  through the outlet  112 . The user inhales humidified gases supplied through the inspiratory conduit  122 , and exhales into the expiratory conduit  124 . The inspiratory conduit  122  and/or expiratory conduit  124  can each include a heating element, for example, a heating wire, to help maintain the gases at a desired temperature and to reduce the likelihood of significant condensation formation in the conduits. 
     Before use, an operator, such as medical personnel, must correctly connect the various components to set up the system  100 . Because of the variety of components and number of connections that must be made, set-up of the system  100  can be a complex process that requires special training to complete properly. The humidification system  100  can include various features as described herein to simplify the set-up process and reduce the likelihood of an incorrect set-up. In some embodiments, certain usability features advantageously can help reduce the total number of steps and time required during the set-up process. Some features described herein also can help make set-up more intuitive for the user, which can reduce the need for specialized in-service training. 
     To begin set-up, the operator installs the humidification chamber  104  on the heater base  102  by sliding the chamber  104  onto the heater base  102  under a rim edge  106  (shown in  FIG. 3 ) that helps hold the chamber  104  in place. The heater plate  108  can be spring loaded in some configurations such that the base of the chamber  104  presses downward upon the heater plate  108  and a protruding portion  105  of the chamber  104  can be captured between the heater plate  108  and the rim edge  106 . Preferably, a guard  107  along a front portion of the rim edge  106  is depressed to enable the lower portion of the chamber  104  to access the heater plate  108  and then the guard  107  reverts to a non-depressed position once the chamber  104  is installed. This advantageously provides positive feedback that the chamber  104  is fully installed on the base  102 . In some configurations, the forwardmost portions of the rim edge  106  (e.g., the portions of the rim edge  106  that define an opening for insertion of the chamber  104 ) are configured with a raised or enlarged opening  109  that ramps downward. The opening  109  preferably comprises a lower surface that is elevated above an upper surface of the non-depressed guard  107 . In such a manner, the opening  109  provides a visual clue to the operator that the protruding portion  105  can be inserted into the opening  109 . Further insertion of the chamber  104  into the opening  109  causes the guard  107  to be depressed and facilitates full insertion of the chamber into the heater base and can help guide the chamber  104  into place. Thus, these visual details can indicate to the operator that the chamber  104  slides into place under the rim edge  106 . This can also help inform the operator that the guard  107  can be depressed to later remove the chamber  104  from the heater base  102 . Preferably, the chamber  104  has details to depress the guard  107  when the operator attempts to remove the chamber  104  from the heater base  102 . Moreover, by providing an uneven upper surface to the rim edge  106 , the operator is less likely to believe that the chamber  104  should be placed atop the rim edge  106 , resulting in poor thermal conductivity, because such a placement will lead to an uneven positioning of the chamber  104 . 
     Humidification chambers, such as the chamber  104 , often have a generally rounded shape with generally smooth sides, which can make it difficult for the operator to hold the chamber  104  during set-up and installation. In setting up the humidifier, the chamber  104  will be grasped and then slid into position on the heater base  102 , as described above. Therefore, as shown in  FIG. 4D , the chamber  104  can include grips  168  to advantageously allow the operator to hold the chamber  104  more easily during installation. In some embodiments, for example as illustrated in  FIG. 4D , the grips  168  are positioned at particular locations on the chamber  104  to help guide the operator to correctly orient the chamber  104  when sliding the chamber  104  onto the base  102 . In some embodiments, the grips  168  extend partially or completely around the chamber  104 . The grips  168  can include one or more of, for example, depressions or cavities on the chamber  104  surface, vertical fins, a textured surface, and/or a handle. In the illustrated configuration, a sidewall of the chamber includes recesses that extend inwardly toward the chamber. The recesses can include ribs or the like to enhance the ability of a user to grip the chamber by the recesses. The recesses can be positioned along a forward facing surface. In some configurations, the upwardly extending ports of the humidifier chamber can include openings that face rearward while the recesses are concave into the humidifier chamber and facing forward. The forward facing grips help orient the chamber for installation. In some configurations, the recesses extend only partially up the full height of the chamber. In some configurations, the recesses are opposed to each other such that a gripping force can be applied with fingers and thumb by the user. 
     With reference to  FIG. 4A , the humidification chamber  104  can be packaged with port caps  160  covering the inlet  110  and the outlet  112 . The port caps  160  can seal or generally enclose the chamber  104  during shipping and storage. In the illustrated embodiment, an intermediate member extends between and connects the port caps  160 , and the intermediate member includes a pull tab or loop  161 . The pull tab  161  advantageously allows the user to remove the port caps  160  more easily during the appropriate stage of set-up. The pull tab  161  is visually intuitive such that the user will typically understand that he or she is to pull on the pull tab  161  without requiring additional instructions. The port caps  160  can include legs  162  that extend into the inlet  110  and the outlet  112  and that restrain the float  150  in position for shipping. In some configurations, the liquid conduit  118  can be wound around, and can be contained by, a winder  166  provided on the chamber  104 . During set-up, after the humidification chamber  104  is installed on the heater base  102 , the port caps  160  can be removed, preferably prior to the liquid conduit  118  being unwound and connected to the liquid source via a spike  164 . Once the spike  164  connects to the liquid source, liquid will begin filling the chamber  104 . However, if the liquid conduit  118  is connected to the liquid source before the port caps  160  are removed, there is a risk of the chamber  104  over-filling because the float  150  is still restrained and cannot function to slow or stop the flow of liquid into the chamber  104 . 
     To reduce the likelihood of overfilling, in some embodiments, the chamber  104  is packaged with the liquid conduit  118  captured between the inlet port  110  and the outlet port  112  of the chamber  104  and the port caps  160 . The liquid conduit  118  can further be somewhat obscured from the operator until the port caps  160  have been removed. Preferably, however, the presence of the liquid conduit  118  below the port caps  160  can be viewed with the port caps  160  in position, which leads the operator to remove the port caps  160  to access the liquid conduit  118 . Furthermore, removal of the port caps  160  preferably results in the unwinding or unfurling of the liquid conduit  118 . This packaging arrangement also reduces or eliminates any need for a winder  166  to contain the liquid conduit  118  and the set-up steps of removing the winder  166  from the chamber  104  and unwinding the liquid conduit  118  from the winder  166 . In some embodiments, the spike  164  and/or liquid conduit  118  are free-floating and not constrained by a winder  166  or the port caps  160 . This can help reduce possible operator confusion as to whether the liquid conduit  118  should be unwound during act-up. In some arrangements, the spike  164  freely hangs exposed to further encourage removal of the port caps  160 . In some configurations, the spike  164  is partially exposed and partially captured by the port caps  160  which encourage removal of the port caps  160  to access the spike  164 . 
     Additional features can help reduce the likelihood of operators mistaking the port caps for operational components of the system intended to remain in place during use. For example, an alternative port cap  170  can include a single flat surface spanning the top of both ports and simple side faces encircling the ports and, optionally, the liquid conduit  118  as shown in  FIGS. 4B and 4C . This design can give the port cap  170  the appearance of a lid to be removed from the chamber  104  before use. The port cap  170  can also include a lip detail around some or all of a perimeter of the flat top surface that the operator can grip for removal. The flat top surface provides a surface for an optional instruction label or a label having an image of, e.g., a trash can to indicate to the operator that the port cap  170  is supposed to be removed and discarded. In some configurations, the port caps can be formed of a material or have a coloration that will confirm an instinct to dispose of the port caps. 
     With reference to  FIG. 4D , another example embodiment of a port cap  170  that can be used with a winder  166  includes a cap body  172  and a float retainer  174  having a tab or pull loop  176  and legs  162  that extend into the inlet  110  and the outlet  112  to restrain the float  150 . The cap body  172  can be formed to be at least partially translucent or substantially transparent to reveal the conduit contained within the cap body  172 . The cap body  172  can include an arrow and/or other visual or other indicators to direct the operator on the correct direction for insertion of the chamber  104  on the heater base  102 . In some embodiments, the cap body  172  can include a label that includes instructions for set-up of the chamber to increase the likelihood of a correct or desired sequence of set-up steps being followed by people performing set-up operations. In some embodiments, the float retainer  174  is separate from the cap body  172  and can be removed from the chamber  104  before the cap body  172  as shown in  FIG. 4E . Removal of the cap body  172  exposes the winder  166 , as shown in  FIG. 4F . Alternatively, the float retainer  174  can be integrally molded with or coupled to the cap body  172  so that both components are removed simultaneously, for example, by pulling on the pull loop  176 . The pull loop  176  can advantageously allow the port cap  170  to be removed more easily. Both embodiments advantageously ensure that the float retainer  174  is removed when the winder  166  is exposed so that the float  150  is unrestrained before the liquid conduit  118  is connected to the liquid source. In some embodiments, the winder  166  is coupled to the chamber  104  with clips or other features that connect to, clip to or otherwise engage the chamber ports. As shown in  FIG. 4F , the liquid conduit  118  can extend from a liquid inlet  117  in the chamber  104 , around the winder  166 , and into the winder  166  through a vent  167  to couple to the spike  164 , which can be seated within the winder  166  as shown in the illustrated embodiment. In the illustrated embodiment, the cap body  172  is sized and shaped to also cover the liquid conduit  118  when in place for shipping and/or storage. In some configurations, the winder  166  includes features to secure the spike in a horizontal position (e.g., a shipping position) and in a non-horizontal or vertical position (e.g., a testing position). For example, the winder  166  can have a generally oval shape and can include a longitudinal receptacle  186  within the winder  166  configured to receive and/or to secure the spike in a horizontal shipping position. The winder  166  can also include a generally circular receptacle  188  configured to receive a grip portion  190  of the spike  164  (shown in  FIG. 4J ) so that the spike  164  can be placed in a generally vertical position for testing. The liquid conduit  118  can be secured in the liquid inlet  117  with an adhesive such as glue or any other suitable technique. A tubing holder  119  can help secure the liquid conduit  118  to a portion of the winder  166  or to the top of the chamber  104  and help route the liquid conduit  118  from the liquid inlet  117  to the winder  166 . In some embodiments, the operator can remove the spike  164  from the winder  166  and unwind the liquid conduit  118  from the winder  166  to connect the spike  164  to the liquid source. In some embodiments, the operator can remove the winder  166  from the chamber  104  and discard the winder  166  after unwinding the liquid conduit  118 . 
     Additional embodiments of liquid conduit  118  packaging are shown in  FIGS. 4G and 4H . In both illustrated embodiments, the liquid conduit  118  is wound into a looped configuration, for example, by winding the liquid conduit  118  around a jig. In some embodiments, a label  218  is attached to the liquid conduit before winding and used to secure the liquid conduit  118  in the looped configuration. In the embodiment of  FIG. 40 , the looped liquid conduit  118  is placed within a foldable card  178  coupled to the top of the chamber  104 . The card  178  can be made of cardboard, plastic, a flexible material, or any other suitable material, and a bottom portion  178   a  can be secured to the chamber  104  with an adhesive and/or by cutouts  280  configured to be placed around the chamber inlet and outlet ports. A top portion  178   b  of the card  178  can be folded over the bottom portion and secured with cutouts configured to be placed around the chamber inlet and outlet ports and/or with port caps  160 . In some embodiments, the spike  164  is secured to a base of the card  178  between the top and bottom portions via a slot or clip. The bottom portion  178   a  of the card can include a slit  282  to accommodate the liquid conduit  118  extending between the card  178  and the liquid inlet  117 . In some configurations, the looped conduit can be placed width-wise on the card. In the embodiment shown in  FIG. 4H , the looped liquid conduit  118  is placed in a molded cavity  111  on the top of the chamber  104  and protected by a tube enclosure  179 , which can include port caps  160 . A bottom surface of the tube enclosure  179  can include a feature to secure the spike  164 . In some embodiments, a label with branding, instructions, and/or other information can be attached to the tube enclosure  179 , the card  178  (e.g., the top portion  178   b  or the card  178 ). In other words, in some configurations, one or more of the card (e.g., the top portion  178   b  of the card  178 ) and the tube enclosure  179  can incorporate one or more surfaces that can be used for instructions (e.g., unpacking instructions, set-up instructions or the like), labels or warnings. In some configurations, the card  178  can include sequential instructions that increases the likelihood of a correct or desired sequence of set-up steps being followed by people performing set-up operations. For example, the card  178  can be provided with sequential or staggered steps to follow. In some configurations, the card  178  or another component can explain only steps that involve exposed or accessible components. 
     As shown in  FIGS. 4F and 4I , the spike  164  can be packaged with a spike cap or sheath  165  that the operator removes before use, as shown in  FIG. 4J . The sheath  165  can include a tab or a similar feature for easier removal of the spike  164  from the winder  166  and/or of the sheath  165  from the spike  164 . In the illustrated embodiment, the sheath  165  includes a loop or ring  265 . If desired, the user can use the ring  265  to hang the sheathed spike  164  on, for example, a medical stand, until the user is ready to use the spike  164 .  FIGS. 4K-4L  illustrate another example embodiment of a spike  164  packaged with a sheath  165  including a ring  265 .  FIG. 4M  shows the sheath  165  alone. As shown in  FIGS. 4L and 4M , the ring  265  can be lifted to an approximately 90° angle relative to the sheath  165  to allow the user to more easily grasp the ring  265  and/or more easily hang the ring  265  on a medical stand. In some configurations, the cap is not connected to any other member such that the operator knows to remove the cap. Labels also can be used to instruct the operator on how to set up the liquid conduit  118  and liquid source. Typically, humidification systems  100  utilize water to humidify gases passing through the humidification chamber  104 . To indicate to the operator that the spike should be connected to a water bag rather to another type of liquid, such as saline, the liquid conduit  118  and/or the chamber  104  can include labels, e.g., reading “H 2 O.” Preferably, any such visual indicator, including the label, is positioned closer to the spike than to the body of the chamber when the conduit is stretched outward. The label on the liquid conduit  118  can also help draw the operator&#39;s attention to the water spike  164 , which may not be obvious to the operator when concealed by the spike cap. The chamber  104  can also include labels to indicate the appropriate water level. 
     In some configurations, a spike can be secured to tubing using any suitable technique. For example, the spike can be secured to tubing using adhesives, sonic welding, interference fit, or the like. A label then can be attached to the tubing. In some configurations, the label can be loosely looped over the tubing and can include a sticky end (e.g., exposed adhesive). In some configurations, the label can be positioned closer to the spike than to another end of the tubing. The tubing can be wound around a jig or the like and secured in a looped configuration using the label (e.g., using the sticky end to tack the end of the label to another portion of the label). When winding the tubing, the ends preferably are provided with enough slack to connect the tubing and spike to the chamber. The end without the spike can be secured to the chamber using any suitable technique. In some configurations, the end without the spike can be inserted into a water inlet hole of the water chamber and fixed with glue or the like. The ends of the loop of tubing can be placed over or between the inlet and outlet ports of the chamber. The spike can be secured into a receptacle. In some configurations, the receptacle can be formed in, or secured to, a portion of the chamber. In some configurations, the spike is secured to the chamber with the point extending away from the chamber for testing. Testing can be conducted on the assembled chamber. After testing, the spike can be removed from the chamber and the spike and tubing can be secured in any suitable manner for shipping, including those set forth above. 
     The humidification system  100  can include reusable temperature and/or flow probes at or near the humidification chamber  104 . For example, a flow sensor can be positioned in the chamber inlet  110  to sense the flow rate of the gases entering the chamber  104  from the gases supply  130 . A temperature sensor can be positioned in the chamber inlet  110  to sense the temperature of the gases entering the chamber  104  from the gases supply  130 . A temperature sensor can be positioned in the chamber outlet  112  to sense the temperature of the humidified gases leaving the chamber  104 . A flow sensor can also or alternatively be positioned in the chamber outlet  112  to sense the flow rate of gases leaving the chamber  104  to be delivered to the user. 
     Reusable temperature and/or flow sensor probes  206  can be integrated into a sensor cartridge module  200 , as shown in  FIG. 5B .  FIG. 5C  shows the sensor cartridge module  200  connected to the heater base with an electrical cable. The sensor cartridge module  200  in  FIG. 5B , however, is mechanically and electrically connected to the heater base  102  via a spine  210  and can therefore provide for the transfer of power to the sensors while also providing a mounting location for the sensors, for example but without limitation. In some configurations, the spine  210  and the port cap can have an interfacing configuration such that movement of the chamber with the port cap in position toward the spine during mounting of the chamber to the heater base will cause the spine to lift the port cap from the chamber. Such a configuration increases the likelihood of the operator removing the port cap from the chamber. Other suitable configurations also can be used. 
     The sensor cartridge module  200  also allows for the transfer of data between the sensors and the processor  114  in the heater base  102 . The chamber inlet  110  and outlet  112  can have apertures  140 ,  142  therethrough, for example as shown in  FIG. 6 . Probe membranes or grommets  144  sized and shaped to receive the temperature and/or flow probes  206  can be positioned within and pneumatically seal the apertures  140 ,  142 . In the configuration of  FIG. 5B , the operator is encouraged to position the chamber base below the rim edge  106  because otherwise the probes attached to the spine will not properly align with the respective apertures. 
     Correct insertion of the chamber  104  into the heater base  102  can automatically position the sensor probes  206  within the apertures  140 ,  142  of the chamber inlet  110  and outlet  112 . This can advantageously allow for an easier set-up compared to separate reusable sensors, which must be manually inserted and electrically connected to the heater base  102 , and reduce the possibility of improper electrical connection, improper pneumatic sealing and/or assembly. The probe membranes  144  protect the probes from direct contact with the gases passing into and out of the chamber  104 . The probes therefore can be reused without requiring cleaning and storage of the probes  206  and disconnection and reconnection of wires between uses. 
     To help guide the operator through installation of the chamber  104  on the heater base  102  and proper connection with the sensor cartridge module  200 , the chamber  104  and sensor cartridge module  200  can include lead-in features, such as corresponding male and female connections. For example, one or more of the base  102  and the cartridge module  200  can include structures that mate with structures  201  on the chamber  104 . In the configuration of the chamber  104  shown in  FIG. 4F , the structures  201  are recessed portions. Thus, the chamber  104  can have a shorter vertical height on the portion closest to the heater base  102  when mounted while the chamber  104  has a taller vertical height on the portion that is positioned away from the cartridge module  200 . Such a configuration reduces the likelihood of the chamber being inserted into the base  102  backwards, which can result in damage to the sensors. The cooperating formations greatly increase the likelihood that coupling of the chamber  104  to the base  102  is only achieved in a correct rotational orientation of the chamber  104 . Moreover, the cooperating structures can provide visual cues to the proper rotational orientation of the chamber  104 . The cooperating structures can be a male on the base and a female on the chamber, a female on the base and a male on the chamber, or any combination of male and female portions on the base and the chamber. 
     By way of another example, the sensor cartridge module  200  can include a central male projection  202  configured to slide into a female recess  204  in the chamber  104 . Alternatively, the chamber  104  can include a male projection configured to slide into a center of the sensor cartridge module  200 . Preferably, the female recess  204  is configured in such a manner that only one orientation of the chamber relative to the male projection  202  is possible. Any other configuration or snap together assembly can be used. In some configurations, the chamber  104  can include a chamfered or angled edge or protrusion  205  on the lateral sides, for example, but without limitation. These protrusions  205  can cooperate with a structure of the base  102  or on the cartridge module  200 . The cooperation preferably helps to pull or encourage the chamber  104  into a fully seated position relative to the base  102 . Thus, the protrusions  205  and the cooperating structures provide another example of structures that can orient and properly position the sensor probes  206  relative to the chamber. These means for orienting the chamber relative to the heater base also advantageously aid proper positioning of the sensor probes  206  within the chamber ports. Advantageously, when the chamber  104  docks on the sensor cartridge module  200 , the sensor probes can be automatically inserted into the chamber ports to the appropriate distance or depth. In other words, the risk of the probes  206  not fully inserting to the ports of the chamber  104  can be reduced or eliminated. Preferably, the connection between the sensor cartridge module  200  and the chamber  104  is generally horizontally (e.g., parallel with an upper surface of the heater plate). 
     In some configurations, the chamber can have recess that accommodates a protrusion from the spine or other portion of the heater base. Such a configuration can help guide the chamber into position on the heater base in a desired rotational orientation. In some configurations, rather than being translated into position, the chamber can be rotated into position on the heater base. For example, slots can be provided with posts that can slide vertically downward into the slots such that rotation of the chamber will position the posts under the rim edge  106 . In some configurations, if the sensor cartridge module  200  is mounted to the chamber before the chamber is mounted to the heater base, rotation of the chamber can establish an electrical connection between components mounted to the chamber (e.g., sensors) and the heater base. Rotation of the chamber also defines a horizontal connection direction. Other configurations also are possible. 
     Some humidification systems  100  also include temperature and/or flow rate sensors at various locations in the breathing circuit to monitor conditions of the gases as they travel through the system  100  to and from the user  128 . Some such systems include reusable temperature sensors at or near the user end of the inspiratory conduit  122  to ensure the gases reaching the user  128  are at an appropriate temperature. Because the various conduits of the circuit are typically disposable, reusable temperature sensors must be separately coupled to the inspiratory conduit  122  during set-up and must further be connected to the heater base  102  for power and data transfer. The user may forget to connect the sensor and/or sensor cable entirely, or may inadvertently fail to fully insert the sensor into the inspiratory conduit  122 , which can skew the sensor data. According to some embodiments of the present disclosure, a single-use user end temperature sensor and associated sensor cable can be integrated with the inspiratory conduit  122 . This can advantageously eliminate the steps of connecting a separate sensor and sensor wires during set-up, as well as the steps and time required to clean and store reusable sensors. 
     In some embodiments, the sensor cartridge module  200  can allow for power and data transfer between the heater base  102  and the inspiratory conduit  122  user end temperature sensor and an inspiratory conduit  122  heater wire. The inspiratory conduit  122  chamber end connector can include an electrical connection for coupling to a corresponding connection on the sensor cartridge module  200 . This provides a simpler alternative to using a reusable sensor cable to provide an electrical connection between the user end temperature sensor and the heater base  102  and a reusable heater wire adapter cable to provide an electrical connection between the inspiratory conduit  122  heater wire and heater base  102 . The user end temperature sensor and heater wire can be coupled to the electrical connection of the inspiratory conduit  122  chamber end connector via wires that are integrated in or run alongside the exterior of the inspiratory conduit  122 . 
     If the expiratory conduit  124  includes a heating element, e.g., a heater wire, the heating element is typically powered via an electrical cable connecting the heating element to the heater base  102 . To help simplify set-up, both ends of the heating element electrical cable can have plugs of the same design. Corresponding sockets can be located on the heater base  102  and the expiratory conduit  124  gases supply end connector. Either end of the heating element electrical cable can be coupled to either the expiratory conduit  124  gases supply end connector socket or the socket of the heater base  102 . The operator therefore does not need to spend excess time determining the correct orientation for the heating element electrical cable. 
     As explained herein, the breathing circuit can include multiple conduits requiring multiple connections to the chamber  104 , the interface  126 , and/or the gases supply  130 . The length of the conduits can make them difficult to handle and control during set-up, increasing the risk of the conduits being accidentally dropped on the ground and possibly contaminated. To improve handling and control during removal from packaging and set-up, the circuits can be packaged and held together in a looped configuration with a circuit sleeve  260  as shown in  FIG. 7A . In some embodiments, the sleeved conduits can be packaged in a protective plastic bag or the like. In some embodiments, the circuit sleeve  260  is made of cardboard or a thin plastic sheet, although other materials are also possible. The circuit sleeve  260  can be looped or wrapped around the conduits and closed or held together with, for example, staples, tape, and/or an adhesive, e.g., glue. In some embodiments, ends of the sleeve  260  have interlocking features to close the sleeve  260  around the conduits, for example, interlocking slits or a tab and corresponding slot. The conduits can also be held in a looped configuration by tape, rubber bands, straps, or the like. 
     The looped configuration can advantageously allow the operator to hang the conduits on, for example, the forearm, the heater base, or another object to free up the operator&#39;s hands for other set-up tasks. In some embodiments, the circuit sleeve  260  includes a hole  262  that can be used to hang the looped conduits on a hook, for example, a hook used to hang the water bag or an I.V. bag, as an alternative to placing the conduits on other hospital surfaces that can increase the risk of contamination. The circuit sleeve  260  can be positioned on the conduits to conceal selected conduit connectors and help direct the operator&#39;s attention to visible conduit connectors, which can be the connectors that should be connected first during the set-up process. If the operator makes the appropriate connections with the visible conduit connectors before removing the circuit sleeve  260  to expose the remaining connectors, the operator will have a reduced number of possible connections, thereby making it easier and more likely to correctly complete the set-up. In some embodiments, the circuit sleeve  260  can include set-up instructions, in writing and/or pictures, to help direct a preferred set-up sequence to achieve the correct set-up. The circuit sleeve  260  can also be positioned on the conduits to cover and/or isolate any sharp edges or corners (e.g., portions of the connectors) to help reduce the possibility of damage to, for example, other circuit components, the chamber, and/or the packaging material during shipping or the like. 
     To help reduce the likelihood of incorrect connections during set-up, the conduit connectors, chamber inlet  110  and outlet  112 , gases supply output  132  and input  130 , interfaces  126 , and/or Y-piece  127  can have varying diameters to help prevent incorrect connections from being made. In some embodiments, some or all of the connections can include details, such as rib details, that allow the appropriate components to be connected, but inhibit improper connections. For example, the chamber outlet  112  or inspiratory conduit port can include a rib detail  250  circumferentially surrounding the port  112  as shown in  FIG. 7B . The inspiratory conduit chamber connector can include a corresponding rib detail  254  configured to engage the chamber outlet port rib detail  250  as shown in  FIG. 8 . The chamber inlet or supply conduit port can similarly include a circumferential rib detail  252  to engage a corresponding rib detail  256  on the supply conduit chamber connector. Other components, such as an inspiratory tube user end connector, expiratory tube user end connector, expiratory tube gases supply end connector, and/or supply conduit gases supply end connector can include outwardly extending rib details. In some configurations, different diameters can be used to make it difficult if not impossible to physically connect the wrong conduit to the wrong port. In addition, as described above, it is possible to form each end of each hose to have a unique configuration to help reinforce the desired connections. Other configurations are also possible. 
     In some embodiments, various components can be color coded to help guide the operator through the set-up process and help reduce the likelihood of incorrect connections. For example, the supply conduit  120  chamber end connector and chamber  104  inlet  110  port can be similarly colored to a first color, for example, green, to indicate to the operator that those two components are intended to be connected. Similarly, the inspiratory conduit chamber end connector and chamber outlet port can be color-coordinated to a second color, for example, blue. For a dual-limb circuit, the interface  126  and/or Y-piece  127  can be color-coordinated to a third color, for example, grey. For a single-limb circuit, the interface and the inspiratory conduit patient-end connector can be color-coordinated to a fourth color, for example, blue. The sensor cartridge module  200  temperature and flow probes  206  can be color-coordinated with probe membranes  144 , for example turquoise. An adapter cable and plugs for the expiratory conduit heating element can be color-coordinated with sockets on the expiratory conduit gases supply end connector and the heater base  102 , for example, yellow. The components intended to be discarded during set-up, for example, the port caps  160 ,  170 , winder  166 , a Y-piece cap, and/or a cap for the water spike  164  can be colored similarly, for example, semi-transparent yellow or orange. Preferably, the cap for the water spike  164  is transparent, translucent or otherwise configured with slots, gaps, holes or the like to indicate to the operator that the spike is positioned within the cap. The supply conduit gases supply end connector and expiratory conduit gases supply end connector can be color-coded, for example, pink. In some embodiments, the conduits themselves can be differentiated through color. For example, the supply conduit  120  can be green, the inspiratory conduit  122  can be blue, and the expiratory conduit  124  can be white. In some embodiments, colors may be selected so that operators with reduced color recognition (such as red-green color blindness) are still able to differentiate the different components. In some arrangements, where an order is preferred, the color coding to be that over color mixing (e.g., red for first connections, orange for second connections, yellow for third connections, green for fourth connections and blue for fifth connections, for example but without limitation). Thus, patterns can be used to encourage proper progression as well as proper connections. In such configurations, LED, lights or color filters over lights can be used to show the color of the connections on the electric display or the colors can simply be shown on a display screen. Of course, other configurations and color palettes are also possible. In some embodiments, user instructions and/or errors can refer to the different components by their color. 
     In addition to or instead of color-coordinating the various components, the components can include corresponding symbols and/or text to indicate parts intended to be connected together. In some configurations, the first connections can be labeled “1” or “A” with the second connections being labeled “2” or “B,” by way of example. In some embodiments, one or more of the conduits can include labeling indicating the proper direction of gas flow through the conduit in use. For example, the supply conduit  120  can include one or more arrows and, optionally, text similar to “TO HUMIDIFIER,” pointing from the gases supply  130  end to the chamber  104  end. Similarly, the inspiratory conduit  122  can include arrows and optional text (e.g., “TO PATIENT”) pointing from the chamber end to the user end, and the expiratory conduit  124  can include arrows and optional text (e.g., “FROM PATIENT”) pointing from the user end to the gases supply end. Any suitable combinations or selection of shapes, colors, sizing, and/or symbols can be used to help a user make the desired connections and/or make the desired connections in the desired order. Further, in some embodiments, connectors of different components may be configured not to be able to connect to one another. For example but without limitation, the inspiratory conduit can have a connector that connects to only the outlet of the humidifier. In such embodiments, the connectors would reduce the likelihood of improperly connecting the component because the components would be very difficult, if not impossible, to connect incorrectly. 
     To further simplify set-up of the breathing circuit, in some embodiments, the supply  120  conduit, the inspiratory  122  conduit, and, optionally, the expiratory  124  conduit can be coupled into a one-piece circuit, for example as shown in  FIG. 9A . In some embodiments, the user ends of the inspiratory  122  conduit and the expiratory  124  conduit can be coupled to a Y-piece  127  configured to be coupled to the interface  126  in use. The Y-piece  127  can be packaged with a disposable cap  180  covering the user end to help inhibit contamination of the conduits and connections during set-up. The electrical connectors and cables for temperature and flow sensors and heating elements can also be integrated into the one-piece circuit. In some embodiments, the chamber  104  can be provided pre-coupled with the one-piece circuit as well. 
     The conduits can be joined together or coupled via, for example, a mesh-type wrap or sheath surrounding at least some portion of the conduits. In some configurations, multiple portions of the conduits to be joined to form a multiple lumen structure can be joined with separate connecting means, including but not limited to mesh-type wrap, sheaths, belts, connectors, clips or the like. In some embodiments, the supply conduit  120  and the inspiratory conduit  122  can be removably coupled to the expiratory conduit  124  with individual clips. This can advantageously allow for the expiratory conduit  124  to be unclipped from the supply  120  conduit and the inspiratory  122  conduit and removed from the circuit when not needed. 
     In some embodiments, two or more of the conduits are structured to releasably connect together. In some embodiments, all of the conduits are structured to releasably connect together. A first conduit (e.g., the inspiratory conduit) can comprise a first portion of one of a hook material or a loop material and a second conduit (e.g., the expiratory conduit) can comprise a second portion of the other of a hook material or a loop material. The first and second portions can be configured to releasably connect together in a hook-and-loop arrangement. Other releasable connection systems can additionally or alternatively be used, such as a series of magnets whereby the two portions include magnets of opposite polarity, for example but without limitation. In another configuration, the outer wall of the inspiratory conduit and the outer wall of the expiratory conduit can be corrugated such that the peaks and troughs of the corrugation are mushroom-shaped. In such a configuration, the peaks of one conduit are configured to releasably snap-fit into the troughs of the other conduit such as shown in  FIG. 9B , for example but without limitation. In such a configuration, the conduits may be directly connected to one another. The size and shape of the peaks and troughs can be the same on both conduits or can be complementary to reduce or eliminate the likelihood of, for example but without limitation, two expiratory conduits connecting together. 
     The one-piece circuit advantageously reduces the number of connections required during set-up and reduces the possibility of incorrect assembly. Additionally, during set-up of traditional systems, the various components may be placed on a table or bed to allow for sorting and identification. Components can be misplaced or fall to the floor, thereby risking damage and/or contamination. The one-piece circuit advantageously helps reduce these problems. The one-piece circuit with integrated electrical connectors and cables also allows for the various electrical connections to be made during set-up with the components to be connected being positioned in close proximity to each other. In some embodiments, a beating element connector plug  182  of the expiratory conduit  124  can be located along the length of the expiratory conduit  124  rather than at the gases supply  130  connector. The plug  182  can be positioned and configured to be connected to a socket on the sensor cartridge module  200  or elsewhere on the heater base  102 , for example, on the front of the heater base  102  to improve visibility of and access to the socket. In such embodiments, the plug  182  may be automatically connected to the sensor cartridge module  200  when the expiratory conduit  124  and/or the chamber  104  is connected to the heater base  102 . 
     Various features can help improve the ergonomics of the humidification system  100 . For example, the socket on the expiratory conduit gases supply end connector can be oriented at, for example, about a 45° angle from a plane defined by the end of the conduit. The angle can enhance the visibility of the socket when the expiratory conduit  124  is connected to the either horizontally or vertically oriented return  134  of the gases supply  130 . The angle can also help reduce the likelihood that the socket will be obstructed by other components or equipment making set-up more difficult. The heater base  102  socket can be located on a front face of the heater base  102  to enhance visibility and ease of access as compared to placement of the socket on, for example, a side of the heater base  102  or elsewhere. 
     In some embodiments, the expiratory conduit  124  gases supply  130  end connector and/or the supply conduit  120  gases supply  130  end connector can have an elbow shape. For example, the connectors can have an angle of about 120°. The elbow shape can advantageously allow the operator to position the direction of the expiratory conduit  124  and/or supply conduit  120  to and from the gases supply  130  so that the conduits do not obstruct other system components, such as the heater base  102  display. Any or all of the connectors, such as one or more of the expiratory conduit  124  and the supply conduit  120  gases supply end connectors and the inspiratory conduit  122  and the expiratory conduit  124  user end connectors can include grip details to help the operator more easily grip the connectors and perform a twisting motion for inserting and removing medical taper connectors. The grip details can be especially beneficial for operators wearing surgical gloves. 
     In some embodiments, the heater base display  103  can be located on an upper surface of the spine  210 , for example as shown in  FIG. 11 , for easier viewing. In the illustrated embodiment, the upper surface of the spine  210  and therefore the display  103  are oriented at an angle. The angled orientation can advantageously allow for an improved or easier view of the display  103  for the operator, particularly, for example, if the heater base  102  is positioned below the operator&#39;s horizontal line of sight. In some embodiments, the upper surface and/or display  103  can be oriented at an angle of about 22° from vertical, although other angles are also possible. In some embodiments, one or both of the supply conduit and inspiratory conduit chamber end connectors can have an angled or elbow shape. For example, in the embodiment of  FIG. 1 , the supply conduit chamber end connector  257  has an elbow shape so that it can be angled away from the heater base  102 . The angled or elbow configuration can advantageously inhibit or prevent the connector and/or conduit from substantially obscuring the display  103 , which serves to improve display visibility. In some embodiments, one or both of the supply and inspiratory conduit chamber end connectors can have an angle of about 112° so that the connector extends from the chamber port at an angle of about 22° above horizontal when coupled to the port, although other angles are also possible. In some embodiments, the spine  210 , display  103 , and/or one or both chamber end connectors can be configured so that the connector(s) is below the display  103  and/or a bottom edge of the upper surface of the spine  210 , e.g., the connector(s) extends below a line extending from the bottom edge of the display  103  perpendicular to the plane of the display and/or below a line extending from the bottom edge of the upper surface of the spine  210  perpendicular to the plane of the upper surface. 
     Additional features can assist the operator with the overall set-up process. For example, packaging for the consumable components of the system  100  can include a schematic diagram illustrating the set-up procedure and/or step-by-step instructions.  FIG. 10  illustrates a sequential method for setting up a humidification system  100 . The method can include some or all of: installing the chamber  104  on the heater base  102 , removing the port cap(s)  160 ,  170 , removing the spike  164  from the winder  166 , unwinding the liquid conduit  118  and removing the winder  166  from the chamber  104 , coupling the spike  164  to a liquid source, coupling the supply conduit  120  to the chamber inlet  110 , coupling the supply conduit  120  to the gases supply  130 , coupling the inspiratory conduit  122  to the chamber outlet  112 , and coupling the inspiratory conduit  122  to the Y-piece  127  or interface  126 . The method can further include coupling the expiratory conduit  124  to the interface  126  or the Y-piece  127  and the gases supply  130 . 
     Another example embodiment of a humidification chamber  304  installed on a heater base  302  having a sensor cartridge module  400  is shown in  FIG. 12 . The heater base  302 , sensor cartridge module  400 , and/or chamber  304  can include any of the features shown and described herein with respect to other embodiments. 
     Like the heater base display  103  of  FIG. 11 , the heater base display  303  of the heater base  302  shown in  FIG. 12  can be located on an upper surface of the spine  301  for easier viewing. The upper surface of the spine  301  and therefore the display  303  can also be oriented at an angle as shown to allow for an improved or easier view of the display  303 . In some embodiments, the upper surface and/or display  303  can be oriented at an angle of about 22° from vertical, although other angles are also possible. In some embodiments, the display  303  or one or more portions of the display can be touchscreen. The display  303  can include touchscreen portions in combination with physical buttons, knobs, and/or the like. Touchscreen portions can advantageously provide greater user interaction possibilities than physical buttons and knobs alone. In some embodiments, the display  303  can include any of the features described in U.S. Provisional Application No. 61/893,758, filed Oct. 21, 2013, the entirety of which is hereby incorporated by reference herein. 
     Similar to humidification chamber  104 , humidification chamber  304  includes a protruding portion  305 , an inlet  310 , an outlet  312 , and a liquid inlet  317 , as shown in  FIGS. 13A-13B . As shown, the liquid inlet  317  can be positioned near a front of the chamber  304 . The liquid conduit  118  can extend from the liquid inlet  317  and can be secured in the liquid inlet  317  with an adhesive such as glue or any other suitable technique. This placement places the liquid conduit  118  farther from the heater base display  303 , which can advantageously reduce possible obstruction of or interference with the display  303  by the liquid conduit  118 . This can be particularly advantageous if the display  303  is a touch screen display such that contact by the liquid conduit  118  could be interpreted as a display input. Placement near the front of the chamber  304  can also help prevent or inhibit the liquid conduit  118  from being caught between the heater base  302  and chamber  304  when the chamber  304  is installed on the heater base  302 . In the illustrated embodiment, the inlet  310  extends upward from the chamber  304 , and the outlet  312  has an elbow shape such that the outlet  312  extends upward then bends to extend toward the front of the chamber  304 . In other words, the outlet  312  extends away from the heater base  302  when the chamber  304  is installed on the heater base  302 . In the illustrated embodiment, the outlet  312  bends to an angle of about 90°. 
     In some embodiments, the chamber  104  can be packaged with a single port cap  360 ,  360   a ,  360   b  having a single float-retaining leg, for example as shown in  FIGS. 14A-14P . In the illustrated embodiments, the port cap  360  is configured to cover the inlet  110 , and the float-retaining leg extends into the inlet  310  to restrain the float(s). As shown, the port cap  360  can also cover the spike  164 . Covering the spike  164  with the port cap  360  can advantageously encourage the user to remove the port cap  360  before use, thereby freeing the float(s). Positioning the spike  164  under the port cap  360  also prevents or inhibits the user from being able to connect the spike  164  to a water bag before the float-retaining leg has been removed from the inlet  310  to free the float(s) so that the float(s) can function to, for example, prevent or inhibit overfill. 
     Use of a single port cap  360  can advantageously allow for the outlet  312  to have an elbow configuration as compared to capping both the inlet  310  and outlet  312  ports. In some embodiments, the chamber  304  is shipped and stored in a hygienic consumable package. Therefore, leaving the outlet  312  uncovered does not significantly increase the risk of contamination of the chamber  304  during shipping or storage. A single port cap  360  can also allow for the inspiratory conduit  122  to be preassembled with the chamber  304  if desired. In some embodiments, the inspiratory conduit  122  includes a connector configured to couple the conduit  122  to the outlet  312 . For example, the connector and/or outlet  312  can include various features as described in U.S. Provisional Application No. 61/919,485, filed Dec. 20, 2013. The connector can be configured to clip onto the chamber  304 , which can advantageously allow for the inspiratory conduit  122  and chamber  304  to be pre-assembled in the packaging for shipping and storage. This can advantageously reduce the number of connections the user is required to make. 
     In the embodiment of  FIGS. 14A-14F , the port cap  360   a  includes a first portion  362   a  configured to cover the inlet  310  and a second portion  364   a  that extends forward from the first portion  362   a  and is configured to cover the spike  164  in a shipping position, as shown in  FIGS. 14B, 14D, 14F . In some configurations, the spike  164  can be in a horizontal shipping position. A top surface of the first portion  362   a  can be downwardly offset from a top surface of the second portion  364   a  so that the top of the first portion  362   a  is at least substantially flush with the top of the inlet port  310 . In the embodiment of  FIGS. 14K-14P , the port cap  360   b  includes a first portion  362   b  configured to cover the inlet  310 , a second portion  364   b  configured to cover the spike  164  in a vertical shipping position adjacent the front of the chamber  304  as shown in  FIGS. 14L, 14N, and 14P , and a ramped intermediate portion  363  extending between and connecting the first portion  362   b  and the second portion  364   b.    
     The second portion  364   a ,  364   b  of the port cap  360   a ,  360   b  can include features configured to retain the spike  164  when the port cap  360   a ,  360   b  is removed from the chamber  304 , for example as shown in  FIGS. 14G-14H . In some embodiments, the port cap  360   a ,  360   b  includes a hook, loop, hole or the like that a user can use to more easily remove the port cap  360   a ,  360   b  and/or to hang the port cap  360   a ,  360   b  containing the spike  164  on a medical stand until the user is ready to connect the spike  164  to a water bag. For example,  FIGS. 14G-14J  illustrate a port cap  360  that is generally similar to the port cap  360   a  of  FIGS. 14A-14F  but also includes a loop hole  367  in the second portion  364 . The loop hole  367  can also allow the user to see a portion of the spike  164  so that the user is further prompted to remove the port cap  360  to access the spike  164 . In the illustrated embodiment, the port cap  360  also includes a graphic, for example, a graphic of a person disposing of trash in a bin. This can advantageously indicate to the user that the port cap  360  is intended to be removed and discarded. 
     The port cap  360 ,  360   a ,  360   b  can be secured to the inlet  310  by friction between the two components. In some embodiments, for example as shown in  FIGS. 140-14J , the first portion  362 ,  362   a ,  362   b  of the port cap  360 ,  360   a ,  360   b  can include an outer ring  370  configured to at least partially encircle an outer perimeter of the inlet  310  and an inner ring  372  configured to at least partially encircle an inner perimeter of the inlet  310 . In some embodiments, the port cap  360 ,  360   a ,  360   b  is secured to the inlet  310  by friction between an inner surface of the inlet  310  and an outer surface of, for example, the inner ring  372 . In other embodiments, the port cap  360 ,  360   a ,  360   b  can be scoured to the inlet  310  by friction between an inner surface of the outer ring  370  and an outer surface of the inlet  310 . The first portion  362 ,  362   a ,  362   b  further includes the float-restraining leg  374 . In some embodiments, the float-restraining leg  374  is formed integrally with and/or is a continuation of the inner ring  372 . For shipping and storage, the port cap  362 ,  362   a ,  362   b  is coupled to the chamber  304  such that the leg  374  extends into the inlet  310  to engage a tab  152  extending from the float  150 . 
     In some embodiments, the first portion  362   b  of the port cap  360   b  of  FIGS. 14K-14P  can include one or more tear strips  365 , for example as shown in  FIG. 14L . The first portion  362   b  can include a second tear strip  365  located on an opposite side of the first portion  362   b  from the tear strip  365  shown in  FIG. 14L . In use, the user pulls up on the second portion  364   b  to begin removing the port cap  360   b . The forces on the second portion  364   b  cause the intermediate portion  363  to begin to lift, which in turn applies an upward force to the first portion  362   b . When the second portion  364   b  has been lifted a sufficient amount and/or a sufficient amount of force has been applied to the second portion  364   b  and transferred through the intermediate portion  363  to the first portion  362   b , the first portion  362   b  begins to tear along the tear strip(s)  365 . The first portion  362   b  therefore can open similar to a clamshell to allow the user to more easily remove the port cap  360   b  from the inlet  310 . 
     The feedset or liquid conduit  118  can be wound into a looped configuration and secured with a label  218 , for example as shown in  FIGS. 4G and 411  and described in the accompanying disclosure herein. The end of liquid conduit  118  secured to the liquid inlet  117  and the end of the liquid conduit  118  secured to the spike  164  can extend from the looped portion in the same direction so that the label  218  can slide off of the liquid conduit  118  as the user is setting up the system. Alternatively, the ends of the liquid conduit  118  can extend from the looped portion in opposite directions, and the user can release the liquid conduit  118  from the looped configuration by tearing the label  218 . In some embodiments, this can allow for easier and quicker set-up because removing the label  218  to release the liquid conduit  118  can be easier and quicker than unwinding the liquid conduit  118  from a winder. 
     In some embodiments, the chamber  304  includes a handle  368  in lieu of or in addition to grips  168 . In some embodiments having an elbow shaped outlet  312 , a conduit or conduit connector coupled to the outlet  312  will extend forward. This could make it more difficult for a user to grasp the grips  168 . Therefore, the handle  368  can advantageously improve access to the chamber  304  and make it easier for the user to grasp the chamber  304  when the conduit is connected to the outlet  312 . The handle  368  and/or grips  168  can advantageously allow the user to grasp the chamber  304  more easily during installation and/or removal of the chamber  304  from the base  302 . The handle  368  and/or grips  168  can also allow the user to apply the force required to remove the chamber  304  from the base  302  more easily. The handle  368  and/or grips  168  are visually intuitive such that a user will typically understand the function of these features without requiring specific instructions. The handle  368  can also act as a brace, support, or pocket for the liquid conduit  118  during shipping and storage. For example, the handle  368  can provide a partially enclosed capture area and/or shelf  369  (shown in  FIG. 141 ) for the liquid conduit  118  during shipping and storage. 
     With reference now to  FIG. 25 , a further chamber assembly  600  is illustrated. The chamber assembly can include a chamber  602  that includes an inlet port  604  and an outlet port  606 . In the illustrated configuration, the inlet port  604  extends generally vertically while the outlet port  606  extends generally horizontally or at some angle other than generally vertically. The chamber  602  also includes a handle  608 . A shelf  610  can extend between a portion of the handle  608  and the body of the chamber  602 . In some configurations, the shelf  610  may not be attached to one of the body of the chamber  602  and the handle  608 . The chamber assembly  600  also includes a water fill port  612 . In some configurations, the water fill port  612  is positioned between the handle  608  and the ports  604 ,  606 . Other configurations are possible. The chamber assembly  600  can have any suitable configuration. In some configurations, components illustrated in  FIG. 25  may be omitted, or may be removed and replaced by components from any of the above-described embodiments, or the like. 
     In the illustrated configuration, a port cap  614  covers the inlet port  604  during shipping and storage, for example.  FIG. 31  illustrates a varied industrial design for the port cap  614 . With reference to  FIG. 26 , the port cap  614  can be a two piece configuration. The port cap  614  can include a collar  616  and a post  618 . The collar  616  and the post  618  can be separable. The collar  616  can have a port encircling support  620 . The support  620  can have any suitable configuration. In some configurations, the support  620  is a generally planar surface that includes an opening that is sized and configured to receive the inlet port  604 . 
     A retainer  622  can extend upwardly from the support  620 . The retainer  622  can define a forward-facing opening. In some configurations, the retainer  622  can be formed by a rectangular frame that is positioned generally forward of the inlet port  604 . The retainer  622  and the support  620  can be integrally formed in some configurations. 
     The post  618  can be inserted into the inlet port  604 . The post  618  can include a lid  626 . The lid  626  can overlie at least a portion of the inlet port  604 . The lid  626  can overlie at least a portion of the collar  616 . In some configurations, the lid  626  can overlie the entire collar  616 . In some configurations, the lid  626  can include a downwardly extending flange  628 . The flange  628  can generally enshroud three sides of the collar  616 . In some configurations, the flange  628  is slightly spaced from the retainer  622 . 
     With reference to  FIG. 28 , the post  618  of the port cap  614  also can include a finger  630 . The finger  630  can be integrally formed with the lid  626 . The finger  630  is configured to be received inside of the chamber  602 . The chamber  602  can include one or more float  632 ,  634 . The floats  632 ,  634  control operation of a valve that, in turn, controls admission of fluid into the chamber  602  through the water delivery conduit  624 . Further description of the float system can be found in U.S. Provisional Application No. 61/873,777, filed on Sep. 4, 2013 and U.S. Provisional Application No. 61/870,156, filed on Aug. 26, 2013, each of which is hereby incorporated by reference in its entirety. 
     With reference to  FIG. 29 , the inlet port  604  of the chamber  602  can include one or more internal structures  636 . The one or more internal structures  636  can be used to address flow or splashing within the flow passing through the inlet port  604 . In the illustrated configuration, the one or more internal structures  636  can be a baffle. The baffle  636  extends at least partially below the inlet port  604 . 
     The finger  630  is configured to extend through the inlet port  604  and beyond the one or more internal structures  636 . The finger  630  can have a portion above the structures  636  and a portion below the internal structures  636 . The finger  630  can be connected to the lid  626  at a location generally vertically higher than the internal structures  636  and the finger  630  can contact at least one of the floats  632 ,  634  at a position vertically lower than the internal structures  636 . 
     In the illustrated configuration, the finger  630  can include a first contact structure  640  and a second contact structure  642 . The first contact structure  640  can be positioned between the second contact structure  642  and the lid  626 . The first contact structure  640  can contact the primary float  634  while the second contact surface  642  can contact the secondary float  632 . The secondary float  632  can include the control tab  638  and the second contact surface  642  can contact the control tab  638 . A similar configuration also can be used with the primary float  634  and the first contact structure  640 . 
     As shown in  FIG. 27 , a water delivery conduit  624  can be wrapped about the inlet port  604 . The wrapped water delivery conduit  624  can be inserted into the port cap  614  through the forward facing opening defined by the retainer  622 . The wrapped water delivery conduit  624  can be positioned such that the inlet port  604  extends through the loop with the support  620  underlying the loop. The post  618  can be inserted into the port  604  with the finger  630  extending beyond the baffle  636 . The finger  630  can hold the secondary float  632  and the primary float  634  in such a position that the valve that controls the flow of water into the chamber is open. The finger  630  can be secured in position by friction forces between the post  618  and the inlet port  604 . The lid  626  and the flange  628  generally enclose the wrapped water delivery conduit  624 . As shown in  FIG. 27 , a spike  644  can be connected to the water delivery conduit  624 . The spike  644  can be housed between the handle  608  and the chamber  602 . In some configurations, the spike  644  can be supported by the shelf  610  that is positioned within at least a portion of a gap defined between the handle  608 . 
     With reference now to  FIG. 30 , during insertion of the chamber  602  into the heater base, at least a portion of the port cap  614  can be lifted from the chamber  602 . In the illustrated configuration, the heater base can include a lifting surface  650 . The lifting surface  650  can contact a contact surface  652  of the port cap  614  during insertion of the chamber  602  into the heater base. In some configurations, the contact surface  652  is a portion of the post  618 . In some configurations, the contact surface  652  is a portion of the flange  628 . In some configurations, the contact surface  652  is a lower edge of the flange  628 . In some configurations, the contact surface  652  is a portion of the collar  616 . In some configurations, the contact surface  652  is a lower surface of the collar  616 . 
     As the chamber  602  is docked into position, the lifting of the post  618  releases the floats  632 ,  634 . In addition, the lifting of the post  618  reveals the coiled fluid delivery conduit  624 . In addition, because the post  618  includes the finger  630  and because the coiled delivery conduit  624  wraps around the finger  630 , removal of the finger  630  enables removal of the conduit  624 . For at least these reasons, the connection of the spike  644  to a fluid source prior to releasing of the floats  632 ,  634  is unlikely. Thus, overfilling of the chamber  602  is less likely with the illustrated port cap  614 . 
     With reference to  FIGS. 32-37 , an additional chamber assembly  700  is illustrated. The chamber assembly can include a chamber  702  that includes an inlet port  704  and an outlet port  706 . In the illustrated configuration, the inlet port  704  extends generally vertically while the outlet port  706  extends generally horizontally or at some angle other than generally vertically. The chamber  702  also includes a handle  708 . A shelf  710  can extend between a portion of the handle  708  and the body of the chamber  702 . In some configurations, the shelf  710  may not be attached to one of the body of the chamber  702  and the handle  708 . The chamber assembly  700  also includes a water fill port  712 . In some configurations, the water fill port  712  is positioned between the handle  708  and the ports  704 ,  706 . Other configurations are possible. The chamber assembly  700  can have any suitable configuration. In some configurations, components illustrated in  FIG. 32  may be omitted, or may be removed and replaced by components from any of the above-described embodiments, or the like. For example, although the example embodiment of  FIG. 32  includes a handle  708  and shelf  710 , the chamber assembly  700  need not include the handle  708  or shelf  710 . 
     In the illustrated configuration, a port cap  14  covers the inlet port  704  during shipping and storage, for example. With reference to  FIGS. 35-37 , the port cap  714  can be a two piece configuration. The port cap  714  can include a collar  716  and a post  718 . The collar  716  and the post  718  can be separable. The collar  716  can have a port encircling support  720 . The support  720  can have any suitable configuration. In some configurations, the support  720  is a generally planar surface that includes an opening that is sized and configured to receive the inlet port  704 . 
     A retainer  722  can extend upwardly from the support  720 . The retainer  722  can define a forward-facing opening. In some configurations, the retainer  722  can be formed by a rectangular frame that is positioned generally forward of the opening for the inlet port  704 . The retainer  722  and the support  720  can be integrally formed in some configurations. 
     The post  718  can be inserted into the inlet port  704 . The post  718  can include a lid  726 . The lid  726  can overlie at least a portion of the inlet port  704 . The lid  726  can overlie at least a portion of the collar  716 . In some configurations, the lid  726  can overlie the entire collar  716 . In some configurations, the lid  726  can include a downwardly extending flange  728 . The flange  728  can generally enshroud three sides of the collar  716 . In some configurations, the flange  728  is slightly spaced from the retainer  722 . 
     With reference to  FIG. 35 , the post  718  of the port cap  714  also can include a finger  730 . The finger  730  can be integrally formed with the lid  726 . The finger  730  is configured to be received inside of the chamber  702  and can be used to secure one or more floats in position in a similar manner to or the same as that described above. 
     As shown in  FIG. 32 , a water delivery conduit  724  can be wrapped about the inlet port  704 . The wrapped water delivery conduit  724  can be inserted into the port cap  714  through the forward facing opening defined by the retainer  722 . The wrapped water delivery conduit  724  can be positioned such that the inlet port  704  extends through the loop with the support  720  underlying the loop. The post  718  can be inserted into the port  704  with the finger  730  extending into the chamber  702 . 
     The lid  726  and the flange  728  generally enclose the wrapped water delivery conduit  724 . As shown in  FIG. 32 , a spike  744  can be connected to the water delivery conduit  724 . The spike  744  can be received within a sleeve  745 . In some configurations, the sleeve  745  is connected to the port cap  714 . In some configurations, the sleeve  745  is connected to at least one of the collar  716  and the post  714 . In the illustrated configuration, the sleeve  745  is connected to the collar  716 . The sleeve  745  can be connected to the collar  716  in any suitable manner. The sleeve  745  can be joined to the retainer  722 . In some configurations, the sleeve  745  can be integrally formed with the retainer  722 . In some configurations, the sleeve  745  can be formed separate of the retainer  722  and secured thereto in any suitable manner. In the illustrated configuration, the sleeve is pivotally connected to the collar  716 . In the some configurations, the sleeve  745  is pivotally connected to the retainer  722 . In some such configurations, the sleeve  745  has a flange  747  that is connected to the retainer  722 . In some such configurations, the flange  747  extends upward from an edge of the retainer  722 . In such configurations, the sleeve  745  can pivot downwardly when then spike  744  is positioned within the sleeve  745 . 
     With reference now to  FIGS. 32 and 35 , the port cap  614  can include a lifting structure  748 . In some configurations, the lifting structure  748  can be joined to any suitable surface of the port cap  614 . In the illustrated configuration, the lifting structure is joined to the lid  726 . In some configurations, the lifting structure is joined to the front of the lid  726 . In some configurations, the lifting structure  748  is pivotable relative to the port cap  614 . The lifting structure  748  can have any suitable configuration. In the illustrated configuration, the lifting structure  748  is a ring. In some configurations, the lifting structure  748  can be a tab, hook or any other suitable structure. The lifting structure serves as a visual indicator to help encourage removal of the port cap  614  while also facilitating the removal. 
     The heater base  302  can include a sensor cartridge module  400  similar to sensor cartridge module  200 . Similar to chamber  104  and sensor cartridge module  200 , chamber  304  and sensor cartridge module  400  can include lead-in features to help guide the operator through installation of the chamber  304  on the heater base  302  and help prevent or inhibit improper set up. For example, as shown in  FIGS. 12 and 15 , the sensor cartridge module  400  can include a central male projection  402  configured to slide into a female recess  404  in the chamber  304  as shown in  FIGS. 13A-13B . As shown, the recess  404  extends forward past a midpoint of or greater than halfway across the chamber  304 , and the male projection  402  of the sensor cartridge module  400  extends past the midpoint of or greater than halfway across the chamber  304  when the chamber  304  is installed on the base  302 . In some embodiments, this causes the male projection  402  to engage the chamber  304  before the chamber  304  otherwise engages the base  302 , which can advantageously help guide the user in orienting the chamber  304  correctly on the base  302 . For example, this feature can prevent or inhibit the user from attempting to install the chamber  304  by placing the protruding portion  305  above or on top of the rim edge  106 . When the chamber  304  is properly installed, the top of the male projection  402  of the sensor cartridge module  400  and the top of the front of the chamber  304  can form an at least substantially continuous or consistent slope. This can advantageously provide a visual cue to the user that the chamber  304  has been properly installed. 
     In the illustrated embodiment, the sensor cartridge module  400  also includes a central channel  410  along a lower surface of the central male projection  402 . The central channel  410  is configured to receive a central boss or raised portion  412  on the chamber  304 . As shown, side walls of the central channel  410  can include generally horizontal grooves  414 . The grooves  414  can be configured to receive corresponding rails  416  extending along the sides of the raised portion  412  of the chamber  304 , as shown in  FIG. 13B . When the chamber  304  is installed on the base  302  and coupled to the cartridge  400 , the rails  416  sit in the grooves  414 . The coupling configuration of the rails  416  in the grooves  414  can help inhibit the chamber  304  from excessive tilting. 
     The configuration and arrangement of, for example, the female recess  404  and raised portion  412  on the chamber  304  make the front and rear of the chamber  304  highly asymmetric. This asymmetry, the configuration of the sensor cartridge  400 , and/or the corresponding lead-in features on the chamber  304  and sensor cartridge  400  advantageously prevent or inhibit the user from inserting the chamber  304  on the base  302  backwards or otherwise incorrectly setting up or misaligning the chamber  304  and/or base  302 . The raised portion  412  also provides a visual guide as to the proper orientation of the chamber  304  for insertion on the base  302 . 
     In some embodiments, one or more of the components of the breathing circuit assembly can be packaged for shipping and/or storage with an end cap  500  coupled to one or both ends of the conduit. An example embodiment of an end cap is shown in  FIGS. 16-17 . For example, an end cap  500  can be included on the end of Y-piece  127  as shown in  FIGS. 18 and 19 . The end cap  500  includes a body  502  configured to be inserted into the Y-piece, a flange  504 , and a hook or pull ring  506 . 
     The body  502  comprises frustoconical tapers  508 . The tapers  508  promote a friction fit between the end cap  500  and Y-piece. The tapers  508  also create a seal with the Y-piece. The illustrated embodiment includes three tapers  508 , although more or fewer are also possible. Multiple tapers  508  provide redundancy to help ensure a sufficient seal and friction fit. However, too many tapers  508  can create too great of a contact area. This can make the end cap  500  difficult to remove. In some embodiments, the body  502  can be sized to fit different sized Y-pieces, for example, both adult and infant Y-pieces. 
     The flange  504  is located on the end of the end cap  500  facing the bases or widest parts of the tapers  508 . As shown, the flange  504  has a hexagonal shape. The hexagonal shape helps seal the end of the Y-piece and aids end cap  500  removal. A width or diameter of the flange  504  is greater than an outer diameter of the Y-piece to create an overhang. For example, for a 22 mm diameter Y-piece, the flange  504  can have a width of about 24 mm. The hexagonal shape can also provide a visual indicator that the Y-piece connector is blocked and further inhibits the user from attempting to attach other components while the end cap  500  is in place, which may be more likely if the flange  504  was round. Other non-circular shapes also can be used. 
     The hook  506  extends from the flange  504 . The hook  506  advantageously allows the user to more easily grasp and remove the end cap  500  when needed. The hook  506  also allows the circuit to hang on a medical stand  520  when not in use and/or during system set up, as shown in  FIGS. 18 and 19 . The hook  506  can have a diameter of at least 8 mm to allow the hook  506  to accommodate medical stand hooks  522 . 
     The body  502 , flange  504 , and hook  506  can be integrally formed or molded to create a single-piece end cap  500 . The end cap  500  should be made of a material that is sufficiently strong while remaining soft or pliant enough to inhibit damage to the Y-piece. In some embodiments, the end cap  500  can be made of Thermolast K. In other embodiments, the end cap  500  can be made of Santoprene having a Shore A hardness of between about 20 and 80, for example, about 55. Santoprene has a higher friction coefficient than some alternative materials, which can help improve end cap  500  retention in the Y-piece. 
     Alternative embodiments of end caps  500  are illustrated in  FIGS. 20A-24E . In these embodiments, the flange  504  is circular rather than hexagonal. Additionally, as shown, the hook or pull ring  506  extends from a side of the flange  504  rather than a top of the flange  504 . In some configurations, the hook can be a tab with an aperture defined through the tab. In any event, in the illustrated configurations, the aperture or hook can be positioned off to one lateral side of an axis extending through the body that engages with the component to which the cap is mounted. In other words, the aperture or hook is positioned off to one side of the body and/or flange. Locating the hook  506  to the side of the flange  504  can cause the force used to remove the end cap  500  to be applied in a rotational direction rather than a linear direction. This arrangement can advantageously allow the end cap  500  to be removed with less force. 
     The hook  506  and flange  504  can have varying dimensions. For example, the embodiment of  FIGS. 21A and 21B  has a larger diameter hook  506  and larger diameter flange  504  than the embodiment of  FIGS. 20A and 20B . If the end cap  500  of  FIGS. 20A and 20B  is connected to a Y-piece  127  having an inner shell  124   a  and an outer shell  124   b , the flange  504  covers only the inner shell  124   a  as shown in  FIG. 20B . The flange  504  of the end cap  500  of  FIGS. 21A and 21B  covers both the inner shell  124   a  and the outer shell  124   b  as shown in  FIG. 21B .  FIGS. 22A and 23A  illustrate additional embodiments of end caps  500 , and  FIGS. 22B and 23B  illustrate the end caps of  FIGS. 22A and 23A , respectively, coupled to a Y-piece  127 .  FIGS. 24A-24B  illustrate the end caps of  FIGS. 16, 20A, 21A, 22A, and 23A , respectively, coupled to an alternative Y-piece  227 . The Y-piece  227  of  FIGS. 24A-24E  can be used for an infant patient. 
       FIG. 38  illustrates a system comprising a chamber  25 , a circuit  50  and a cap  800 . The chamber  25  is configured to hold a liquid, such as, for example, water. The chamber  25  is configured to couple with a heating apparatus that, in use, heats the liquid and, thereby, forms vapour. The chamber is configured to couple with a gases source such that gases provided to the chamber are heated and take up the vapour as they travel through the chamber. The heated, humidified gases are delivered by the circuit  50  to the patient. The cap  800  is configured to be attached to the circuit  50 . The illustrated circuit  50  is an example of a circuit to which the cap  800  can be attached and is not meant to be limiting. In an embodiment, the cap  800  is configured to couple with an intermediate respiratory component, such as, for example, a wye-piece, or an additional circuit. 
     Sealing, as herein described, refers to at least partial sealing of a medical component, such as, for example, a circuit. Sealing prevents, or at least partially prevents, dust, or larger contaminants, such as a finger, for example, from entering the circuit. Sealing could be achieved by the use of a tortuous path, a cap, or a cap that provides a tortuous path. The tortuous path substantially seals or at least partially seals the circuit (i.e., may not result in a completely air impervious seal). 
       FIGS. 39A-39D  illustrate the cap  800  in more detail. The cap  800  comprises a ring  801  connected to a plug  804 . The ring  801  may be connected to the plug  804  by a throat  802 . The plug  804  comprises a disc  814  and a body  805 . The disc  814  comprises an upper surface  816  and a lower surface  818 . The disc  814  has a diameter that is larger than the diameter of the body  805 . The disc  814  further comprises a lip  808  that extends from the lower surface  818 . The plug  804  comprises a roughly cylindrical structure defining a tube. The tube comprises a first end and a second end. The first end is sealed by the lower surface  818  of the disc  814 . The second end is branched by a pair of ribs  812  that are perpendicular to each other. The ribs  812  are coupled with the lower surface  818  and abut an internal wall of the body  805 . The plug  804  comprises four segments of three frustoconical tapers  806  adjacent to the body  805 . Each of a plurality of channels  810  is defined between adjacent segments of the frustoconical tapers  806 . The plurality of channels  810  extend into the lower surface  818 . 
     The ring  801  has a diameter large enough to insert a finger. For example, the diameter may be greater than 8 mm. In the illustrated embodiment, the diameter is 25 mm. The ring  801  is configured to enable easy removal of the cap  800  from the circuit  50 . The ring  801  is configured to allow the cap  800  to be removed from the circuit  50  without use of excessive force while the retaining force created by friction between the body  805  and the circuit  50  remains enough to hold the cap  800  in place when the circuit  50  is hung. In an embodiment, the cap  800  is configured to be removed by a force in the range of 5-30 Newtons (N). In an embodiment, the cap  800  is configured to be removed by a force in the range of 5-15 N. In an embodiment, the cap  800  is configured to be removed by a force of about 15 N. This provides a retention force that is strong enough to support the weight of the circuit  50  and yet allows a user to insert and remove the cap  800  without impacting the usability of the circuit  50 . 
     The ring  801  enables the circuit  50  to be hung on a supporting structure, such as a medical stand or hook, for example. This facilitates easy storage of the circuit  50  prior to use, during a pause in use, or following use. The system can be set up prior to use and be ready for use by a patient. 
     The plug  804  is coupled with the ring  801  by the throat  802 . This causes leverage to be applied to the plug  804  when a force is applied to the ring  801 , which reduces the force required to remove the cap  800  from the circuit  50 . The length of the throat  802  can be increased to increase the amount of leverage applied to the plug  804 . In the illustrated embodiment, the length of the throat  802  is 3 mm. The width of the throat  802  can also be Increased to increase the amount of leverage applied to the plug  804 . In an embodiment, the ring  801  is directly coupled to the plug  804  with no intervening throat. This reduces the overall size of the cap  800  but increases the force required to remove the cap  800  from the circuit  50 . 
     The body  805  of the plug  804  couples with the circuit  50 . In the illustrated embodiment, the body  805  is configured to be a male component. Thus, the body  805  is received by the circuit  50  and extends into the interior of the circuit  50 . The body  805  is configured to be held in place in the circuit  50  by, for example, a friction fit. In the illustrated embodiment, the body  805  is configured to fit a 22 mm taper circuit connector. A male component renders the cap  800  independent of the external configuration of the circuit connector. Thus, the cap  800  can be used with different circuits having the same internal connector size, for example, a 22 mm taper. 
     In an embodiment, the body  805  comprises a female component that is configured to receive the circuit  50 . This protects the interior of the circuit from potential damage due to interaction with the body  805 . 
     The size of the cap  800 , or the plug  804 , can be scaled to fit, for example, 8.5 mm, 12 mm, 15 mm, 17 mm, 22 mm, 23 mm, or 30 mm tapers. This enables the cap  800  to be used with a variety of medical components, such as, but not limited to, a wye-piece, medical circuits or interface circuits of different sizes. 
     The body  805  comprises four segmented groups, each comprising three frustoconical tapers  806 . The groups of frustoconical tapers  806  are configured to form a scaling interface with the interior of the circuit  50 . The sealing interface is formed using a friction fit between the frustoconical tapers  806  and the interior of the circuit  50 . The frustoconical tapers  806  hold the cap  800  in place in the circuit  50  during use until sufficient force is applied to remove the cap  800  from the circuit. Three frustoconical tapers  806  are chosen such that the force required to remove the cap  800  from the circuit  50  is within the capabilities of a user and yet exceeds other forces encountered during use. 
     In an embodiment, a single frustoconical taper  806 , or two frustoconical tapers  806 , form the sealing interface with the interior of the circuit  50 . The single or two frustoconical tapers  806  reduce the length of the body  805  that is inserted into the interior of the circuit  50  while facilitating sealing between the body  805  and the interior of the circuit. The single or two frustoconical tapers  806  reduce the force required to remove the cap  800  from the circuit  50 . 
     In a further embodiment, four or more frustoconical tapers  806  form the sealing interface with the interior of the circuit  50 . Pour or more frustoconical tapers  806  improve the sealing between the body  805  and the interior of the circuit  50 . 
     The segmented groups of frustoconical tapers  806  are each separated by the channels  810 . The channels  810  form a path through which gases within the circuit  50  can move into the atmosphere. Thus, the channels  810  provide a way for the gases to vent from the circuit  50  should a user initiate gases flow through the circuit while the cap  800  is in place. The channels  810  are located on the body  805  and, thus, are received by the circuit  50  as the body  805  is inserted into the circuit. The channels  810  are subtle and do not negatively impact the overall look of the cap  800 . As illustrated in  FIG. 39B , the width (w) of each of the channels  810  is 5 mm. In the illustrated embodiment, the depth (d) of each of the channels  810  at the deepest point is 1.3 mm. The depth (d) of each of the channels  810  can be varied provided it remains within manufacturing constraints, for example, greater than 1 mm. A thin material is vulnerable to breakage and a thick material takes time to cool, which can lead to distortion of the parts. 
     In an embodiment, the width of the channels  810  is less than 5 mm, for example, 2 mm. This improves the sealing between the cap  800  and the circuit  50 . In a further embodiment, the width of the channels  810  is greater than 5 mm, for example, 7 mm. This improves the venting capacity of the cap  800 . 
     The four channels  810  may be spaced evenly around the perimeter of the body  805 . This reduces the likelihood of the cap becoming unsealed and disconnecting with the circuit  50  due to an uneven amount of gases being vented to the atmosphere through each channel. Four channels  810  can withstand expected pressures at typical operating pressures, such as 13 kPa at 60 lpm or 20 kPa at 70 lpm. 
     In an embodiment, two channels  810 , substantially evenly spaced around the perimeter of the body  805  maintain a high sealing force between the cap  800  and the circuit  50 . 
     In an embodiment, three channels  810  substantially evenly spaced around the perimeter of the body  805  allow more venting to the atmosphere. 
     In an embodiment, five channels  810  substantially evenly spaced around the perimeter of the body  805  increase the venting of gases to the atmosphere. Thus, more venting of gases to the atmosphere can occur with a larger number of the channels  810 . 
     The illustrated embodiment optimises the sealing force with the venting capacity of the cap  800 . For example, 27% of the sealing diameter of the cap  800  facilitates venting gases to the atmosphere and 73% of the sealing diameter of the cap  800  forms sealing surfaces between the cap  800  and the circuit. A greater venting capacity may negatively impact the sealing of the cap  800 , which may cause the cap  800  to come off in use. Greater sealing of the cap  800  may reduce the venting capacity, which may cause the cap  800  to come off in use. Evenly spaced or substantially evenly spaced channels  810  around the perimeter of the body  805  provides more balanced venting of the gases to the atmosphere. This reduces the chance of the cap  800  coming off upon activation of the gases source. 
     The channels  810  extend into the lower surface  818  of the disc  814 . This facilitates venting of gases from within the interior of the circuit  50  to the atmosphere by preventing the lower surface  818  or the disc  814  from scaling onto the circuit connector, such as might be encountered, for example, if the circuit  50  is coupled to the cap  800  such that the connector is flush with the lower surface  818 . The channels  810  protrude by 0.5 mm into the lower surface  818  of the disc  814 . 
     In an embodiment, the channels  810  extend into the lip  808  of the disc  814  to further facilitate venting of gases from within the interior of the circuit  50  to the atmosphere. The channels  810  protrude into the lip  808  of the disc  814  by 0.5 mm. 
     A pair of ribs  812 , which are perpendicular to each other, branch the diameter of the second end of the tube formed by the body  805 . The ribs  812  provide structural support to the body  805 . This enables the body  805  to be received by the interior of the circuit  50  forming a seal. 
     In an embodiment, multiple ribs  812  provide additional structural support to the body  805 . 
     In a further embodiment, a single rib  812  is used to provide structural support to the body  805 . This reduces the amount of material required to form the cap  800  and simplifies the structure of the cap  800 . 
     The disc  814  forms a barrier that at least partially seals the circuit  50  from the atmosphere. For example, the disc  814  prevents dust and larger contaminants, such as a finger or a medical instrument, from being inserted into the circuit  50  while it is attached to the cap  800 . The disc  814  indicates to the user that the cap  800  should be removed prior to attaching a medical component to the circuit  50 . For example, the disc  814  comprises a diameter that is larger than the diameter of the circuit. In the illustrated embodiment, the diameter of the disc  814  comprises 30 mm, compared with the circuit diameter of 22 mm. 
     In an alternative embodiment, the disc  814  comprises an eye-catching shape, for example, a hexagon or a square, to encourage the user to remove the cap  800  prior to use of the circuit  50 . 
     In the illustrated embodiment, the upper surface  816  of the disc  814  comprises a visual indicator, by way of a drawing, colour, message or instructions to the user. The visual indicator indicates to the user, for example, correct usage of the cap  800  or disposal of the cap  800 . The visual indicator can be embossed, raised or printed onto the upper surface  816 . 
     In an embodiment, the upper surface  816  is colour coordinated with other medical components in the system. In an alternative embodiment, the upper surface  816  comprises a colour that indicates the cap  800  is disposable, such as, for example, red. 
     The lower surface  818  of the disc  814  seals the first end of the tube as defined by the body  805 . The lip  808  surrounds the lower surface  818  of the disc  814 . The lip  808  improves the aesthetic features of the cap  800 , such as, for example, by subtly incorporating the channels  810  into the cap  800 . In the illustrated embodiment, the lip  808  is 1.5 mm high. The lip  808  improves the sealing between the cap  800  and the circuit by sealing onto the exterior of the circuit. 
     The cap  800  is made from a material that does not damage the interior of the circuit when a friction fit is formed between the cap  800  and the interior of the circuit. The material is soft to protect the circuit and yet sufficiently rigid that the structure of the cap  800  is maintained. An example of an appropriate material is a thermoplastic elastomer, a thermoplastic polyurethane, or an elastomer. 
       FIG. 40  illustrates an example embodiment, wherein a cap  900  comprises a plug  904 . The plug  904  comprises a body  905  that is configured to be received by the circuit  50 . The body  905  comprises segmented groups of frustoconical tapers  906  configured to at least partially seal with the interior of the circuit. The segmented groups of frustoconical tapers  906  are each separated by the channels  910 . The channels  910  form a pathway through which gases within the circuit can vent to the atmosphere if a gases source is activated prior to removal of the cap  900  from the circuit. 
     The channels  910  comprise at least one orifice  920  to facilitate venting of gases from the circuit to the atmosphere. The at least one orifice  920  extend through the channels  910  and are configured to form a pathway between the lumen of the circuit  50  and the atmosphere. The channels  910  help to direct the vented gases toward the at least one orifice  920 . In the illustrated embodiment, the channels  910  comprise two orifices  920 . The orifices  920  can be used in combination with the channels  910  to further facilitate venting of the gases from the circuit to the atmosphere. In the illustrated embodiment, the orifices  920  are shown positioned near a lower surface  918  of a disc  914 . Thus, the orifices  920  are positioned open to the atmosphere and are not sealed by the interior of the circuit. As a result, the cap  900  has a greater capacity to vent gases to the atmosphere. 
     In an embodiment, the cap  900  comprises multiple orifices  920 . For example, the cap  900  may comprise three or more orifices  920 , which further facilitate the venting of gases from the circuit. 
     In a further embodiment, the cap  900  comprises at least one orifice  920  with a larger diameter. This increases the capacity of the cap  900  to vent gases from the circuit  50 . As a result, a reduced number of the orifices  920  is used while facilitating additional venting of gases from the circuit. Alternatively, the orifices  920  comprise a smaller diameter. This renders the orifices  920  more subtle and less obtrusive to the user. A smaller diameter also reduces the likelihood of dust or other contaminants entering the circuit. Thus, multiple orifices  920  are used to allow additional venting from the circuit. 
     In a further embodiment, the orifices  920  are positioned on at least one of the frustoconical tapers  906 . The orifices  920  can be used without or instead of the channels  910 . In this embodiment, the sealing surfaces of the cap  900  are increased, facilitating better sealing between the cap  900  and the circuit. 
     In a further embodiment, the orifices  920  are positioned within the portions of the channels  910  that extend into the lower surface  918  of the disc  914 . The orifices  920  thus protrude through the upper surface  916  of the disc  914 . Thus, the channels  910  direct the gases toward both the atmosphere and the orifices  920 . This facilitates greater venting of the gases without negatively impacting the sealing forces of the cap  900 . 
       FIGS. 41A and 41B  illustrate an example embodiment, wherein a cap  1000  comprises a plug  1004 , a disc  1014  comprising an upper surface  1016  and a lower surface  1018 , a pair of ribs  1012  that are perpendicular to each other, and at least one cut-out  1020 . The cut-out  1020  comprises a passageway through at least a portion of the disc  1014  to facilitate venting through the cut-out  1020 . In the illustrated embodiment, two cut-outs  1020  traverse through the lower surface  1018  and the upper surface  1016  of the disc. This enables the gases within the circuit to be vented to the atmosphere. The cut-outs  1020  are positioned opposite each other and near the ribs  1012 . The ribs  1012  may provide an indication as to the position of the cut-outs  1020 . For example, the cut-outs  1020  can be positioned in a vertex that is defined by the ribs. Portions of the cut-outs  1020  may protrude from the upper surface  1016  of the disc  1014  as gases are vented to the atmosphere. The cut-outs  1020  give the cap  1000  the capacity to vent gases to the atmosphere while increasing or maximising the sealing that occurs between the cap  1000  and the circuit. 
     In the illustrated embodiment, the cut-out  1020  is illustrated as a pair of lines forming a right angle. However, in some embodiments, the cut-out  1020  comprises a slit, an orifice (for example, the orifice  920  illustrated in  FIG. 40 ), or any other appropriate form of opening. 
     In an embodiment, multiple cut-outs  1020 , for example, four cut-outs  1020 , are used to facilitate venting of the gases from the circuit. The four cut-outs  1020  are positioned at each of the vertices formed by the ribs  1012 . 
     In a further embodiment, the disc  1014  comprises the at least one cut-out  1020 , for example, around the perimeter of the disc  1014 . The at least one cut-out  1020  is subtly incorporated into the disc  1014 . For example, the at least one cut-out  1020  is incorporated into a pattern, message, or drawing that appears on the upper surface  1016  of the disc  1014 . 
       FIGS. 42A and 42B  illustrate an example embodiment, wherein a cap  1100  comprises a plug  1104 , a disc  1114  that further comprises an upper surface  1116  and a lower surface  1118 , a pair of ribs  1112  that are perpendicular to each other, and at least one orifice  1120 . The at least one orifice  1120  is configured to allow gases within the circuit to vent to the atmosphere via the disc  1114 . Thus, the cap  1100  has capacity to allow venting of gases to the atmosphere while maintaining a maximum sealing force with the interior of the circuit. 
     In the illustrated embodiment, the cap  1100  comprises multiple orifices  1120 . The orifices  1120  extend through both the lower surface  1118  and the upper surface  1116  of the disc  1114 , thereby forming a passageway through which gases can move. The upper surface  1116  comprises a lowered region  1124  that is surrounded by a ledge  1122 . In the illustrated embodiment, the ledge  1122  positions the lowered region  1124  2 mm below the upper surface  1116 . The multiple orifices  1120  are positioned around the perimeter of the lowered region  1124  near the ledge  1122 . The ledge  1122  extends at least partially over the multiple orifices  1120 . This provides a tortuous path for dust or other contaminants to enter the circuit via the cap  1100 . It also enables the multiple orifices  1120  to be more subtly incorporated into the cap  1100 . 
     In an embodiment, multiple orifices  1120  comprise a small diameter, for example, between 1 mm and 5 mm. In the illustrated embodiment, the multiple orifices  1120  are 3.5 mm long (l) and 2.5 mm wide (w). This provides a tortuous path for dust or other contaminants to enter the cap  1100  and is more subtle to incorporate into the upper surface  1116  of the cap  1100 . 
     In an embodiment, the orifices  1120  comprise a large diameter, for example, 5 mm to 10 mm. Thus, less of the orifices  1120  are used to enable gases within the circuit to vent to the atmosphere. A large diameter improves the venting capacity of the cap  1100 . Thus, the cap  1100  is more likely to address what might otherwise be higher pressures of gases within the circuit. In an embodiment, the orifices  1120  on the upper surface  1116  have a length (I) of 1 mm to 10 mm, and a height of 1 mm, which extends from the lowered region  1124  into the ledge  1122 . 
     In a further embodiment, the orifice  1120  comprises a slit or curved rectangular shape. In an embodiment, a single orifice  1120  runs along the perimeter of the lowered region  1124 . In an embodiment, multiple orifices  1120 , for example, two, three, or more orifices  1120 , extend around the perimeter of the lowered region  1124 . The orifices  1120  comprise slits that allow venting of gases from the interior of the circuit to the atmosphere. 
       FIGS. 43A and 43B  illustrate an example embodiment, wherein a cap  1200  comprises a ring  1201 , a throat  1202  and a body  1204 . The body  1204  comprises an inner surface  1206 , an outer surface  1214 , a flange  1208  and channels  1210 . The ring  1201  and the throat  1202  function as described in the above embodiments. The body  1204  is a female part and, thus, is configured to receive the circuit. The exterior of the circuit and the inner surface  1206  are configured to form a sealing surface. The body  1204  comprises the flange  1208  that forms an outer rim of the body  1204 . The flange  1208  is angled outwardly from the inner surface  1206  of the cap  1200 . Channels  1210  are positioned adjacent to the flange  1208 , between the flange  1208  and the inner surface  1206 . The channels  1210  are indentations formed on the inner surface  1206  of the body  1204  and are configured to direct a gases flow from the circuit to the atmosphere. Four such channels  1210  exist in the illustrated embodiment. 
     In use, the cap  1200  is configured to deform if a gases source is activated. For example, pressure in the circuit causes the outer surface  1214  of the cap  1200  to deform such that the position of the cap  1200  relative to the circuit is altered. The cap  1200  moves nearer to the end of the circuit, while remaining coupled with the circuit. The inner surface  1206  of the body  1204  is no longer flush with the exterior of the circuit. This enables gases from within the circuit to vent to the atmosphere through the channels  1210 . 
     In an embodiment, the channels  1210  comprise orifices that extend through the body  1204  of the cap  1200 . This allows direct venting of gases from the circuit to the atmosphere. 
     In a further embodiment, multiple channels  1210 , for example, greater than four channels  1210 , are used to direct gases to the atmosphere. This improves the venting capacity of the cap  1200 . 
     In a further embodiment, the length of the channels  1210  is altered such that the channels  1210  extend into the flange  1208  of the cap  1200 . Thus, less deformation of the cap  1200  is required to enable gases to be directed to the atmosphere. 
     In a further embodiment, the flange  1208  further comprises a crimped edge  1209 . The crimped edge  1209  is coupled with a channel  1210 . Thus, the gases are directed by the channel  1210  to the crimped edge  1209  where they are released to the atmosphere. Thus, the crimped edge  1209  improves the efficiency by which gases are vented to the atmosphere. The crimped edge  1209  also creates a cap  1200  that is pleasing to the eye of the user. A single crimped edge  1209  is evident in the illustrated embodiment of  FIG. 43A ; however, multiple of the crimped edge  1209  could be used. 
     Although this disclosure has been described in the context of certain embodiments and examples, it will be understood by those skilled in the art that the disclosure extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses and obvious modifications and equivalents thereof. While the description above refers to a “user,” it should be noted that the ultimate user can be a patient and the apparatus described herein can be assembled by a nurse, doctor or other healthcare practitioner in a clinical or healthcare related facility as well as a user/patient in a home use, for example but without limitation. In addition, while several variations of the embodiments of the disclosure have been shown and described in detail, other modifications, which are within the scope of this disclosure, will be readily apparent to those of skill in the art. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the disclosure. It should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order to form varying modes of the embodiments of the disclosure. Furthermore, dimensions of various components provided herein are exemplary, and other dimensions may be used. Thus, it is intended that the scope of the disclosure herein should not be limited by the particular embodiments described above.