Abstract:
A therapeutic gas is administered to a patient. A sample gas is drawn from the therapeutic gas supply, and passed through a water-permeable tubular membrane. Concurrently, a section of the water permeable tubular membrane is maintained as a ventilated water permeable tubular membrane, by exposing outer surfaces of the ventilated water permeable tubular membrane to an ambient air flow. The ambient air flow may in some examples be moved over the tubular membrane via forced air such as for example via a fan associated with a housing surrounding the tubular membrane.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Patent Application No. 62/331,694, filed on May 4, 2016, and entitled “APPARATUS AND METHOD FOR HUMIDITY CONDITIONING SAMPLE GAS OF A PATIENT BREATHING CIRCUIT AFFILIATED WITH A VENTILATOR AND/OR NITRIC OXIDE DELIVERY SYSTEM,” the contents of which are incorporated herein by reference in their entirety. 
     
    
     FIELD 
       [0002]    The present disclosure generally relates to the humidity conditioning of sample gas affiliated with a ventilator and/or nitric oxide delivery system. 
       BACKGROUND 
       [0003]    Many patients benefit from receiving therapeutic gas (e.g., nitric oxide gas) in inspiratory breathing gas flow from a breathing circuit affiliated with a ventilator. The ventilator can be, for example, a constant flow ventilator, variable flow ventilator, high frequency ventilator, bi-level positive airway pressure ventilator or BiPAP ventilator, etc.). To provide therapeutic gas to the patient, the therapeutic gas may be injected into the inspiratory breathing gas flowing in the breathing circuit. This inhaled therapeutic gas is often provided via a therapeutic gas delivery system as a constant concentration, which is provided based on proportional delivery of the therapeutic gas to the breathing gas. Further, a sampling system (e.g., affiliated with the therapeutic gas delivery system) may continuously draw in the inspiratory breathing gas flow to at least confirm that the desired dose of the therapeutic gas in the inspiratory breathing gas flow is being delivered to the patient. For example, a sample pump may pull in inspiratory flow (e.g., in the vicinity of the patient) to confirm that the desired therapeutic gas concentration is in fact being delivered to the patient in need thereof. 
         [0004]    One such therapeutic gas is inhaled nitric oxide (iNO). In many instances iNO is used as a therapeutic gas to produce vasodilatory effect on patients. When inhaled, NO acts to dilate blood vessels in the lungs, improving oxygenation of the blood and reducing pulmonary hypertension. Because of this, nitric oxide is provided in inspiratory breathing gases for patients with various pulmonary pathologies including hypoxic respiratory failure (HRF) and persistent pulmonary hypertension (PPH). The actual administration of iNO is generally carried out by its introduction into the patient as a gas along with other normal inhalation gases, for example, by introducing iNO, from an iNO delivery system, into the inspiratory flow of a patient breathing circuit affiliated with a ventilator. 
         [0005]    Separately and/or in conjunction with iNO, patients may receive inspiratory breathing gas flow containing liquid particles (e.g., moisture from humidified air, etc.) and/or other particles. Although this matter in the inspiratory breathing flow may provide additional benefit to the patient, it may interfere with or degrade operation of the sample gas analyzer. For example, the sample gas analyzer itself may work best when it receives sample gas within a given humidity range, and liquid particles as described above may be inconsistent with that range. 
         [0006]    One known technique directed at keeping the sample gas at a desired humidity is to use, as part of the pathway of the sample gas before it arrives at the analyzer, a tubing formed of a sulfonated tetrafluoroethylene based fluoropolymer-copolymer, for example, the commercially available Nafion® tubing. Properties of such tubing include a permeability that is very selective to water and that provides rapid transfer through the tubing walls. Provided that the permeability is maintained, such tubing can provide a mechanism operating as follows: if the humidity level of the sample gas passing through the tubing exceeds an acceptable maximum (and assumedly above ambient), some of that excess humidity will permeate out through the tube walls before the sample gas reaches the analyzer. Conversely, if the humidity level of the sample gas passing through the tubing is below the acceptable minimum (and assumedly below ambient), some of the ambient humidity will permeate in through the tube walls and raise the humidity of the sample gas to be within an acceptable range, prior to reaching the analyzer. 
         [0007]    However, a conventional arrangement of Nafion tubing can form, over time, a dry external layer, i.e., at its outer wall surface, or dry inner layer at its passage wall surfaces, or both. With subscribing to any particular scientific theory, the inventor believes the mechanism of the drying may be a dehydration of the aqueous sulfonic acid inherent to the Nafion construction. Such dry layers can effectively become an obstruction to the above-described humidity conditioning function. This drying and obstructing layer formation can significantly shorten the operational life of Nafion (and equivalent) tubing type humidity conditioners. 
         [0008]    Accordingly, there is a need for a humidity conditioner having the performance that can be obtained with Nafion and, concurrently, a significantly longer operational life than provided by conventional technique Nafion humidity conditioners. 
       SUMMARY 
       [0009]    Aspects of the present disclosure generally relate to apparatuses and methods directed to enhanced performance and extended equipment life in humidity conditioning of sample gas. More specifically some implementations relate to enhancing or controlling the humidity of sample gas affiliated with a ventilator and/or nitric oxide delivery system. Further, some implementations relate to the humidity of sample gas prior to being analyzed by a gas analyzer. Further, some implementations relate to humidity conditioning a sample gas, using Nafion tubing, by passing ambient air over the tubing using a fan or other forced air device. The tubing may be in the form of a coil housed in a housing, with a fan forcing (or blowing) air over the tubing. 
         [0010]    Disclosed aspects include a sample gas conditioning apparatus, and the apparatus can include a housing, at least partially defining a chamber, and at least partially defining an air input path into the chamber and an air egress path from the chamber. In an aspect, the sample gas conditioning apparatus can include a fan, connected to the housing, and configured to urge an ambient air flow through the chamber, the ambient air flow entering through the air input path into the chamber, and exiting the chamber through the air egress path. The sample gas conditioning apparatus can include, in an aspect, a sample gas tube having a section that comprises a permeable material. Disclosed aspects include the section being arranged and supported in the chamber in a configuration wherein at least a portion of the section is a ventilated section, ventilated by the ambient air flow through the chamber. 
         [0011]    Disclosed aspects also include structure for arranging and supporting the ventilated section in the chamber in a configuration, relative to the ambient air flow through the chamber, that establishes flow parameters of the ambient air flow, in regions adjacent to outer surfaces of the ventilated section, at levels that prevent or significantly retard formation of a skin of dry gas around the outer surface of the ventilated section. 
         [0012]    Disclosed aspects also include the sample gas tube having an input end and an output end, and can include the section comprising permeable material providing a passage distance for the sample gas, wherein the passage distance in combination with a flow rate of the sample gas provides, for at least a range of humidity level of sample gas at the input end that is outside of a given acceptable range, a conditioning of the sample gas as it travels the passage distance wherein, at the output end, the humidity level is within the given acceptable range. Disclosed examples include, but are not limited to, an acceptable range that extends from approximately 15% relative humidity to approximately 90% relative humidity. 
         [0013]    Disclosed examples include the sample gas tube having an input and an output, and in an aspect the apparatus can further comprise a connection of the input to a conduit, the conduit being configured to deliver a mixture of a mixture gas and a therapeutic gas to a patient. In an aspect, the sample gas tube can be configured to provide passage of a sample of the mixture of the mixture gas and the therapeutic gas to the ventilated section, and to output, at the output, a humidity conditioned sample of the mixture of the mixture gas and the therapeutic gas. In an aspect the therapeutic gas comprises inhaled nitric oxide. 
         [0014]    Disclosed aspects include the fan being connected to the housing, in an alignment with the air egress path, and in a configuration that urges a negative pressure in the chamber. In an aspect, the negative pressure can effect an urging of the ambient airflow through the airflow input to the chamber, out through the air egress path, and into the fan. 
         [0015]    Disclosed aspects include the water permeable material comprising a sulfonated tetrafluoroethylene based fluoropolymer-copolymer, and include the water permeable material comprising Nafion. 
         [0016]    Disclosed aspects also include the tube walls of the ventilated section providing a tubular membrane, formed of the permeable material, and the permeable material transferring water through the tubular membrane, based on First Order Kinetic reaction. In addition, disclosed aspects include the tubular membrane having a start and having an end, and providing a passage length from the start to the end, wherein based at least in part on the passage length the tubular membrane provides, for at least a range of humidity level of the sample gas at the start that is outside of a given acceptable range, a humidity level of the sample gas at the end that is within the given acceptable range. 
         [0017]    Disclosed aspects include the ventilated section being a coiled tube section, with windings around a winding axis. Disclosed aspects include the coiled section having a winding turn and, in another aspect, having at least two winding turns. 
         [0018]    Disclosed aspects also include a configuration of the air input path, the air egress path, and inner wall surfaces of the housing, relative to the coiled section, that urges the ambient airflow through the chamber according to a flow direction, the flow direction being generally parallel to the winding axis. In addition, disclosed aspects include the winding turns forming a coil winding outer surface, the coil winding outer surface being radially distal from the winding axis, and the chamber being defined, at least in part, by an inner surface of the housing that extends a length along the winding axis and, circumferentially around the winding axis, faces toward the winding axis. 
         [0019]    Disclosed aspects include the housing having a housing cap, having a cap perimeter, and that the housing having housing sidewalls that extend, parallel to the winding axis, from the cap perimeter to a housing open end. In addition, disclosed aspects include the housing sidewalls forming sidewall inner surfaces that can face and have a clearance from the coil winding outer surface. Disclosed aspects also include the housing being configured to provide the air egress path as at least a portion of the housing open end area. In addition, disclosed aspects include the housing cap being a vented housing cap, providing a vent into the chamber, and the air inlet path as comprising the vent. 
         [0020]    Disclosed aspects include the fan as comprising an electric motor, that can be supported in a fan housing, and a rotor shaft and a rotary fan blade attached to the rotor shaft. In addition, disclosed aspects include the housing being configured with a housing mounting flange at the housing open end, and that the fan housing can be secured to the housing mounting flange, in a configuration where the rotor shaft can be parallel to the winding axis. 
         [0021]    Also, disclosed aspects include the fan housing being secured to the mounting flange by an adapter plate, the adapter plate having an adapter plate first face and, opposite and parallel to the adapter plate first face, an adapter plate second face. Described exemplary implementations according to this disclosed aspect include the fan housing being secured, by fan housing mount bolts, to the adapter plate first face, in combination with the housing mounting flange being secured, by housing mount bolts, to the adapter plate second face. 
         [0022]    Disclosed aspects include providing a method for verifying therapeutic gas for delivery to a patient, and exemplary operations can include adding a therapeutic gas as a supplement to a mixture gas, and delivering to the patient, though a conduit, the mixture gas supplemented with the therapeutic gas is delivered. In an aspect, operations can include receiving a gas sample from the conduit, through a gas sample line, of the mixture gas supplemented with the therapeutic gas. Disclosed aspects include humidity conditioning the sample gas, by passing the sample gas through a water-permeable tubular membrane, wherein the sample gas leaving the water-permeable tubular membrane is a humidity conditioned sample gas, and analyzing the humidity conditioned sample gas to determine a mixing ratio. Disclosed aspect include, concurrent with passing the sample gas through the water-permeable tubular membrane, maintaining a section of the water permeable tubular membrane as a ventilated water permeable tubular membrane, by operations that include exposing outer surfaces of the ventilated water permeable tubular membrane to an ambient air flow. 
         [0023]    In an aspect, the therapeutic gas can comprise inhaled nitric oxide. In an aspect, operations in passing the sample gas through the water-permeable tubular membrane can comprise passing the sample gas through a tubular membrane formed of a sulfonated tetrafluoroethylene based fluoropolymer-copolymer. In another aspect, operations in passing the sample gas through the water-permeable tubular membrane can comprise passing the sample gas through a tubular membrane formed of Nafion. 
         [0024]    Disclosed aspects include providing a method directed to humidity conditioning a sample gas, and operations can include passing the sample gas through a water-permeable tubular membrane and, concurrent with passing the sample gas through the water-permeable tubular membrane, establishing a section of the water permeable tubular membrane as a ventilated water permeable tubular membrane, by exposing outer surfaces of the ventilated water permeable tubular membrane to an ambient air flow. 
         [0025]    Disclosed aspects include, in addition, exposing outer surfaces of the ventilated water permeable tubular membrane to the ambient air flow to provide the ambient airflow with characteristics that can prevent or significantly retard formation of a skin of dry gas around the outer surfaces of the ventilated water permeable tubular membrane. 
         [0026]    Also, disclosed aspects include establishing the ventilated water permeable tubular membrane to have a start and an end, and a passage length between the start and the end. Disclosed aspects include the passage length being such that the water permeable tubular membrane provides, for at least a range of humidity level at the start that is outside of a given acceptable range, a humidity of the sample gas at the end within the given acceptable range. 
         [0027]    Other features and aspects of the disclosure will be apparent from the following detailed description, the drawings, and the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The features and advantages of the present disclosure will be more fully understood with reference to the following, detailed description when taken in conjunction with the accompanying figures, wherein: 
           [0029]      FIG. 1  schematically depicts a gas humidity conditioning apparatus, with an exemplary ambient airflow to humidity transfer tubing, in accordance with one or more aspects; 
           [0030]      FIG. 2  illustrates a perspective view, depicting in partially exploded form structures in an example gas humidity conditioning apparatus, with an exemplary implementation of ambient airflow to humidity transfer tubing, according to one or more aspects; 
           [0031]      FIG. 3  illustratively depicts a perspective view of the  FIG. 2  apparatus, in a construct showing an assembled form; 
           [0032]      FIG. 4  illustratively depicts another perspective view of the  FIG. 2  apparatus, according to the  FIG. 3  construct; 
           [0033]      FIG. 5A  illustrates a partial cross-sectional view of the construct of  FIGS. 2 and 3 , cut down a centerline thereof; 
           [0034]      FIG. 5B  illustrates the  FIG. 5A  partial cross-section view, with its exemplary ventilated coiled tube structure removed, to provide additional view of various structures in accordance with one or more aspects; 
           [0035]      FIG. 6  illustratively depicts one flow diagram, representing example operations in a method directed to humidity conditioning and to extending humidity conditioning tube life, and to other features, in accordance with various aspect; and 
           [0036]      FIG. 7  illustratively depicts at least some aspects of implementation of a Nafion tubing enhancing apparatus, in conjunction with a breathing gas supply apparatus, in accordance with various exemplary aspects of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0037]    Generally, aspects of the present disclosure relate to apparatuses and methods to enhance the humidity conditioning of sample gas. More specifically, some implementations relate to enhancing or controlling the humidity of sample gas affiliated with a ventilator and/or nitric oxide delivery system. Further, some implementations relate to the humidity of sample gas prior to its being analyzed by a gas analyzer. Further, some implementations relate to humidity conditioning the sample gas by passing it through a length of Nafion or alternative water permeable tubing and, concurrently, passing ambient air over the tubing using a fan or other forced air device. 
         [0038]    Various examples in the present disclosure refer to Nafion tubing. Reasons include Nafion being a material that is known in the art. Other reasons include the problems to which this application is directed being known to manifest when Nafion is used for humidity conditioning a sample gas. However, references to Nafion are not intended to limit disclosed systems and methods to Nafion tubing. 
         [0039]    For convenience in description, the arbitrary term “selective high permeability material” is hereby introduced and will be introduced to mean: material, including but not limited to sulfonated tetrafluoroethylene based fluoropolymer-copolymer, including Nation, and reasonable equivalents thereto, that exhibits selective, high water permeability, the selectivity and permeability being acceptable for humidifying/de-humidifying sample gas in therapeutic gas delivery systems and having suitable chemical resistance to enable use in therapeutic gas delivery systems. It will also be understood that, except where explicitly stated or made clear from its context to mean otherwise, that the term “Nafion” means: “Nafion or other selective high permeability material.” 
         [0040]    One sample gas conditioning apparatus according to one or more aspects can include a housing, configured to at least partially define a chamber, and to form, or at least partially define an air input path into the chamber and an air egress path from the chamber. An example sample gas conditioning apparatus according to one or more aspects can also include a fan, connected to the housing, in a configuration such that action of the fan urges an ambient air flow through the chamber, the ambient air flow entering through the air input path into the chamber, and exiting the chamber through the air egress path. An example sample gas conditioning apparatus according to one or more aspects can also include a sample gas tube, having a section that comprises a permeable material. The permeable material can be, for example, Nafion. In an aspect at least a portion of the section can be arranged in the chamber as a ventilated section, the ventilated section being ventilated by the ambient airflow through the chamber. In an aspect, the ventilated section can include a coiled tube section. The coiled tube section can comprise, for example, a winding turn, or least two winding turns, or any integer plurality of winding turns, with or without supplement by partial turns. In an aspect, the winding turns of the coiled tube section can be around a winding axis. In a further aspect, the air input path, air egress path, and the housing can have a joint configuration that urges the ambient air flow through the chamber to have a flow direction, the flow direction being generally parallel to the winding axis. However, in other implementations the tube section may have a coil or winding arrangement that has turns that are other than circular. 
         [0041]    It will be understood that in described implementations that include an air input path and flow though the chamber to an air egress path, the structures functioning as the “input air input path” and “air egress path” are only one example. In one alternative implementation, the described fan direction can be reversed, whereupon structure described as input air input path will be the air egress path, and structure described as the air egress path will be the air input path. 
         [0042]    In an aspect “sample gas,” as used herein, can be a sample gas drawn from a delivered therapeutic gas in the context of delivery of therapeutic gas to patients (e.g., patients receiving breathing gas, with therapeutic gas, from a ventilator circuit). The sample gas, for example, may be removed from an inspiratory limb of a therapeutic gas delivery system to be monitored by a sampling device. Applications can include a filtering of the sample gas prior to being humidity conditioned according to disclosed concepts. Humidity conditioning of sample gas according to disclosed concepts, applied to therapeutic delivery systems may, for example, allow improved accuracy in monitoring what is delivered. Such accuracy can provide improved confirmation of dosing (e.g., nitric oxide concentration, etc.) as well as other parameters (e.g., nitrogen dioxide concentration, oxygen concentration, etc.). As an additional benefit, humidity conditioning of sample gas according to disclosed concepts can provide significantly extended service life of the humidity conditioning tubing. This can reduce costs and make continuous monitoring more feasible. 
         [0043]      FIG. 1  shows, in a cross-sectional view, a sample gas conditioning apparatus  100  according to various aspects. 
         [0044]    Referring to  FIG. 1 , apparatus  100  can include a housing  112 , which can be configured to at least partially define a chamber  114 . The housing  112  can include a cap  112 C, and sidewalls  112 S. The cap  112 C can be integral to the housing  112 . Alternatively, the cap  112 C can be secured, by adhesive or other means, to a region of the sidewalls  112 S. In an aspect, the sidewalls  112 S can extend from the cap  112 C (right-to-left in the image plane of  FIG. 1 ) to form a housing open-end, identified by the  FIG. 1  dotted line labeled  116 . 
         [0045]    With continuing reference to  FIG. 1 , the housing  112  may include, for example, a vent  118 , as an air input path to the chamber  114 . It will be understood that “vent” and “air input path” are not limited to being a single passage. In an aspect, the housing open end  116  can function, for example, as described in greater detail later, as an air passage, opening and/or egress from the chamber  114 . 
         [0046]    Referring to  FIG. 1 , in an aspect, the apparatus  100  can include a fan  120 , which, according to one aspect, can be connected or mounted to the housing  112 . The fan  120  may be connected or mounted, for example, in alignment with, or in another cooperative arrangement with the housing open end  116 . The fan  120  can be, for example, an off-the-shelf device, such as readily available from various vendors. The fan  120  can include a frame or housing  122 , which is partially visible in the  FIG. 1  cross-sectional view. The frame or housing  122  can support a motor-driven rotary fan blade (visible in part but not separately numbered). In one example, the fan  120  can urge an ambient airflow in a direction that, in the  FIG. 1  image plane, appears as right-to-left. Accordingly the side of the fan  120  facing toward the housing open end  116  can be termed a “fan input,” and the opposite side can be termed a “fan output.” 
         [0047]    Capacity (e.g., volume per unit time) and electrical power requirements for the fan  120 , e.g., voltage and whether AC or DC, are application-specific. Persons of ordinary skill having possession of this disclosure can readily select and implement the fan  120  without undue experimentation. 
         [0048]    Upon receiving power, the fan  120  can urge an ambient airflow that can enter the chamber  114  through the air input, e.g., the vent  106 , continue through the chamber  114 , and exit from the housing open end  116 .  FIG. 1  labels an example of this ambient airflow according to regions, with “AIR-IN” labeling the ambient airflow entering the chamber  114  through the air input, e.g., the vent  106 , “AIR-CH” labeling ambient airflow through the chamber  114 , and “AIR-EX” labeling ambient airflow exiting the chamber  114  through the housing open end  116 . 
         [0049]    Continuing to refer to  FIG. 1  the system  100  can include a sample gas tube  126 , having an input end (visible in  FIG. 1  but not separately numbered) coupled to a tube input coupler  130 , and an output end (visible in  FIG. 1  but not separately numbered) coupled to a tube output coupler  128 . In an aspect, the entire length of the sample gas tube  126 , from the input end to the output end, can be formed of Nafion or another selective high permeability material. In one alternative, at least the portion labeled “ 126 V,” which will be described as the “ambient air ventilated section  126 V,” can be formed of Nafion or another selective high permeability material. The example of  FIG. 1  may be considered a parallel flow configuration. If the input coupler and output coupler are reversed, as can be the case in some implementations, then the arrangement may be considered a counter-flow arrangement. 
         [0050]    In an aspect, the ventilated section  126 V can be arranged to be within the ambient airflow AIR-CH. In an arrangement such as illustrated in  FIG. 1 , the ambient air ventilated section  126 V is effectively bathed in the ambient airflow. It will be understood that “within the airflow,” in the context of “within the ambient airflow AIR-CH,” means exposure to the ambient airflow AIR-CH sufficient to prevent or significantly retard formation of a skin of dry gas around the outer surface of the ambient air ventilated section  126 V. 
         [0051]    Referring to  FIG. 1 , the ambient air ventilated section  126 V can be configured to include a “coiled tube section” (visible in  FIG. 1 , but not separately numbered). The coiled tube section can comprise, for example, a winding turn (visible in  FIG. 1 , but not separately labeled), or any number of winding turns, such the example two (2) winding turns that are visible in FIG.  1 . In an aspect, the winding turns of the coiled tube section can be wound around a winding axis, such as the winding axis AX. Further aspects of supporting the coiled tube section within the housing  112  are described in reference to  FIGS. 2-5B . 
         [0052]    In an aspect, at least the section of the sample gas tube  126  that forms the ambient air tube section  126 V can be jacketed by a braided plastic, for example polyester, (not explicitly visible in the figures) to mechanically stabilize and stiffen the material. 
         [0053]    Benefits of forming the ambient air ventilated section  126 V as a coiled tube section include, for example, providing a greater passage length within a smaller volume. This can provide, among various benefits, a smaller required chamber  114 , i.e., smaller housing  112 . Another example benefit can be a smaller total flow volume for the ambient airflow AIR-CH. 
         [0054]    Regarding the physical length of the ambient air ventilated section  126 V, this can be determined, without undue experimentation, by a person of ordinary skill having possession of this disclosure. For example, in various applications, all of the following can be established, ascertained, or given up front: i) the water permeability of the tube walls; ii) the rate of the sample gas (or other gas to be conditioned); iii) the expected range of humidity of the received sample gas (or of the other gas to be conditioned); and iv) the acceptable range for the humidity of the conditioned gas. Identifying all of (i) through (iv), for a given application, can be readily performed by persons of ordinary skill in the art. Therefore, further detailed description is omitted. Upon (i) through (iv), being identified, the physical length of the ambient air ventilated section  126 V can be readily determined, for example, by the following guideline in view of this entire disclosure: calculate (or find through simulation) a physical length such that the gas, after traveling that length, will have humidity that has been raised or lowered (from the maximum and minimum extremes of the input humidity range), to within the acceptable range. 
         [0055]      FIG. 2  illustrates a perspective view, depicting in partially exploded form structures in one example gas humidity conditioning apparatus  200 , with an exemplary ambient airflow, in accordance with one or more aspects. The gas humidity conditioning apparatus  200 , with an exemplary implementation of ambient airflow to humidity transfer tubing, will be referred to as “humidity conditioning apparatus”  200 . 
         [0056]    Referring to  FIG. 2 , humidity conditioning apparatus  200  can include a housing  212  having sidewalls  214 , which can be arranged around and extend parallel to longitudinal axis LX, which will be alternatively referred to as the “winding axis” LX. In an aspect, the housing  212  can include an annular end plate  216 . The annular end plate  216  can have an inner perimeter edge (visible in  FIG. 2  but not separately labeled) that can be circumferential around the winding axis LX. The annular end plate  216  can also have an outer perimeter edge (visible in  FIG. 2  but not separately labeled), which can merge with a peripheral rim (visible in  FIG. 2  but not separately labeled) of the housing sidewalls  214 . The housing sidewalls  214  can extend from the peripheral rim in a direction parallel to the winding axis LX, to an opposite peripheral rim (visible in  FIG. 2  but not separately labeled) that merges with a housing end flange  218 . The peripheral rim of the housing  212  that merges with the housing end flange  218  can define an open end (obstructed from view in  FIG. 2 ) of the housing  212 . 
         [0057]    It will be understood that “merge with,” as used in this disclosure, carries no limitation as to structure that effects the merging. For example, “merged with” can include, without limitation, “connected to,” “attached to,” “fused to” and “molded as respective regions or portions of a single structure.” 
         [0058]    Continuing to refer to  FIG. 2 , in an aspect, the housing  212  can include a winding support  220  (partially visible in  FIG. 2 ) that can extend from the inner perimeter edge of the annular end plate  216 , in a direction parallel to the winding axis LX. The annular end plate  216 , in other words, can support the winding support  220  to extend within the housing sidewalls  214 , toward the open end of the housing  212 . Various structure and functionalities of the winding support  220  are described in greater detail in reference to  FIGS. 5A and 5B . 
         [0059]    Continuing to refer to  FIG. 2 , in an aspect, the gas humidity conditioning apparatus  200  can include a fan  222 . The fan  222  can be connected to the housing  212  using, for example, an adapter plate  224 . The fan  222  can include a fan housing (visible in  FIG. 2  but not separately numbered) that can be bolted to the adapter plate  224 . The fan  222  can then be attached to the housing  212  by bolting the adapter plate  224  to the housing end flange  218   
         [0060]    In an aspect, the gas humidity conditioning apparatus  200  can include sample gas tube  226 , having a coiled tube section  226 V. The coiled tube section  226 V can be an implementation of the  FIG. 1  ambient air ventilated section  126 V. In an aspect, the coiled tube section  226 V can be formed of a permeable material, having a high permeability for water. In an implementation, the permeable material can comprise a sulfonated tetrafluoroethylene based fluoropolymer-copolymer. The permeable material, for example, can be Nafion. The sample gas tube  226  can include the tube input end coupled to a tune input coupler  230 , and an output end coupled to a tube output coupler  232 . 
         [0061]    In an aspect, at least the section of the sample gas tube  226  that forms the coiled tube section  226 V can be jacketed by a braided plastic, for example polyester, (not explicitly visible in the figures) to mechanically stabilize and stiffen the material. 
         [0062]      FIG. 3  illustratively depicts a perspective view of the gas humidity conditioning  200  apparatus, in a construct showing an assembled form, with the housing sidewalls  214  rendered transparent. Referring to  FIG. 3 , the arrangement of the coiled tube section  226 V of the sample gas tube  226  is partially visible. 
         [0063]      FIG. 4  illustratively depicts another perspective view of the gas humidity conditioning  200  apparatus, in the construct shown in  FIG. 3 , with the housing sidewalls  214  not transparent. Referring to  FIG. 4 , in an aspect, the winding support  220  introduced in reference to  FIG. 2  can be hollow, with an opening OP. The winding support  220  can also have longitudinal slots  228  and, for each, the annular end plate  216  may provide corresponding cutouts or vents (visible in  FIG. 4  but not separately labeled). Referring to  FIG. 4 , portions of the first (starting from the annular end plate  116 ) three windings of the coiled tube section  226 V are visible through three of the longitudinal slots  228 , and the corresponding cut-outs or vents formed in the annular end plate  216 . 
         [0064]      FIG. 5A  illustrates a partial cross-section view of the  FIGS. 3 and 4  construct, seen from a cut-through plane containing the winding axis LX.  FIG. 5B  illustrates the  FIG. 5A  partial cross-section view, with its exemplary ventilated coiled tube structure removed, to provide additional view of various structures in accordance with one or more aspects. 
         [0065]    Referring to  FIGS. 5A and 5B , the winding support  220  can be configured to support the coiled tube section coil  226 V in a winding configuration having a winding radius R 1  from winding axis LX. The coiled tube section  226 V can be wound around a support surface (not visible in  FIG. 3 ) of the winding support  220 . The support surface of the winding support  220  can be circumferential around and spaced from the winding axis LX by a winding radius R 1  or the coiled tube section  226 V. Inner surfaces  514  (labeled in  FIG. 5B ) of the housing sidewalls  214  can be spaced from the coil winding outer surface. The inner surfaces of the housing sidewalls  514  and the support surface of the winding support  220  can define an annular volume, which can accommodate the coiled tube section  226 V. 
         [0066]    As identified in reference to  FIG. 4 , and as further visible in  FIGS. 5A and 5B , the winding support  220  can have longitudinal slots  228  and, for each of such slots  228 , the annular end plate  216  may provide corresponding cutouts or vents (visible in  FIG. 4  but not separately labeled). 
         [0067]    Referring to  FIGS. 4, 5A and 5B , example operations of the gas humidity conditioning apparatus  200  according to various aspects will now be described. Upon powering the fan  222 , a negative pressure may be induced in portions of the annular volume  512  that remain after inclusion of the coiled tube section  226 V. This pressure can urge ambient airflow AIR-IN to enter that annular volume  512 , through the longitudinal slots  228  in the winding support  220 , and through corresponding cutouts or vents formed in the annular end plate  216 . AIR-IN can urge ambient airflow AIR-CH, which flows over and around the coiled tube section  226 V, and then out as AIR-EX through the fan  222 . 
         [0068]    it will be understood that the combination of the coiled tube section  226 V being wound in the annular volume  512 , around the winding support  220 , which can be hollow with longitudinal slots  228 , can maintain the coiled tube section  226 V as effectively bathed in the ambient airflow. In an aspect, an outer texture of the sample gas tube  226  forming the coiled tube section. This arrangement, in turn, can establish the coiled tube section  226 V as a ventilated tube section  226 V. Benefits and features of the ambient airflow AIR-CH bathing the ventilated tube section  226 V can include, for example, prevention or significant retardation of any formation of a skin of dry gas around its outer surface. In addition, based in part on the aspect of providing a multiple turn coiled (hence longer) ventilated tube, disclosed aspects can deliver a sample gas with acceptable humidity, for at least a range of extremes of humidity, together with extended useful functional life of the tube. 
         [0069]    In the above-described implementations with an air input path and flow though the chamber to an air egress path, the structures functioning as the “input air input path” and “air egress path” are only one example. For example, referring to  FIG. 4 , in the humidity conditioning apparatus  200  the fan  222  can be reversed. The reversal can change the end of the housing proximal to the housing end flange  218  to an “air input path,” and can change the longitudinal slots  228 , and corresponding cut-outs or vents formed in the annular end plate  216  to an air egress path. In addition, the fan  222  having its rotational axis collinear and parallel with the winding axis LX is only one example implementation of a fan to urge the described ambient airflow. In one alternative implementation, fan  222  can be replaced with a fan rotated 90 degrees (not visible in the figures) from fan  222 , in combination with a 90-degree elbow. In another alternative implementation, fan  222  can be replaced by a radial fan. 
         [0070]    According to various aspects, the gas humidity conditioning apparatus  200  (as well as the apparatus  100 ) may be used with sample gas from a patient breathing apparatus. In some cases the ambient air may be approximately 20 degrees C. and 30% relative humidity, such as for example in health care facilities based on ANSI/ASHRAE/ASHE standard 170-2008: class B and class C operating rooms, recovery rooms, critical and intensive care rooms, newborn intensive care rooms, patient rooms and/or newborn nursery suites. In such situations and others, improved performance and extended service life may have significant value. 
         [0071]      FIG. 6  illustratively depicts an exemplary flow diagram of an exemplary method for conditioning of sample gas, using an apparatus as described herein. At process  610 , sample gas is received, such as the  FIG. 1  inlet  130 . This sample gas may be taken from a patient breathing gas apparatus, and for example may be from a fitting off an inspiratory limb. At process  612   a , the sample gas is passed through Nafion tubing, which may be configured with a ventilated coil section, such as the  FIG. 1  ventilated coil section  126 V or the  FIG. 2  ventilated coil section  226 V. Concurrently with process  612   a , at process  612   b  ambient airflow contacts and passes over and around the ventilated coil section  126 V (or  226 V). The ambient airflow may be, for example, the  FIG. 1  or  FIG. 5A  AIR-CH, and can be urged by a fan, such as the  FIG. 1  fan  120  or the  FIG. 2  fan  222 . At process  614 , the sample breathing gas passes out of the Nafion tubing, and is analyzed by a gas analyzer such as described herein and below. 
         [0072]      FIG. 7  illustratively depicts some aspects of exemplary implementations of exemplary gas conditioners as described herein, in conjunction with a breathing gas supply apparatus. An apparatus  700  is used with a ventilator  710 . A supply  712  of supplemental or additive gas such as NO provides a supply to conduit  714  and leads to a flow sensor  716  which may also be connected to the ventilator  710 . At any stage of breathing gas supply, other additional breathing materials such as nebulized drugs may be provided into a stream that travels via conduit  720 . A controller  718  may actuate valves to control, for example, the ratio of NO to the mixture gas in conduit  720 . A patient inhales the content of conduit  720  which may be considered as an inspiratory limb. The patients exhale or excess gas may be considered as an expiratory limb conduit  722 . While the sample gas is illustrated in this implementation as being drawn from the inspiratory limb  720 , it may be drawn from other parts of the patent breathing apparatus. 
         [0073]    In this example, a conduit  724  is in fluid communication with the inspiratory limb and may be referred to as a sample gas line. A filter trap  726  receives some or all of the sample gas. This filter trap  726  may correspond to a filter assembly that removes water and/or particulates from the sample gas. After being filtered by the filter trap  726 , the gas is passed to a gas conditioner apparatus labeled  740 . In an aspect, the gas conditioner apparatus  740  can be, for example the humidity conditioning apparatus  100  described in reference to  FIG. 1 , or the gas sample humidity conditioning apparatus  200  described in reference to  FIGS. 2-5B . After leaving the gas conditioner apparatus  740 , the now humidity-conditioned sample gas can pass to a gas sampling system  728 , and may exhaust via exhaust outlet  730 . In some implementations, the controller  718  may control some operations of the conditioner apparatus ( 100 ,  200 ,  740 ) such as by way of example only, the fan speed thereof. 
         [0074]    The foregoing detailed descriptions are presented to enable any person skilled in the art to make and use the disclosed subject matter. For purposes of explanation, specific nomenclature is set forth to provide a thorough understanding. However, it will be apparent to one skilled in the art that these specific details are not required to practice the disclosed subject matter. Descriptions of specific applications are provided only as representative examples. Various modifications to the disclosed implementations will be readily apparent to one skilled in the art, and the general principles defined herein may be applied to other implementations and applications without departing from the scope of this disclosure. The sequences of operations described herein are merely examples, and the sequences of operations are not limited to those set forth herein, but may be changed as will be apparent to one of ordinary skill in the art, with the exception of operations necessarily occurring in a certain order. Also, description of functions and constructions that are well known to one of ordinary skill may be omitted for increased clarity and conciseness. This disclosure is not intended to be limited to the implementations shown, but is to be accorded the widest possible scope consistent with the principles and features disclosed herein. 
         [0075]    It will be apparent to those skilled in the art that various modifications and variations can be made to the methods and systems of the present description without departing from the spirit and scope of the description. Thus, it is intended that the present description include modifications and variations that are within the scope of the appended claims and their equivalents. 
         [0076]    It will be understood that any of the steps described can be rearranged, separated, and/or combined without deviating from the scope of the invention. For ease, steps are, at times, presented sequentially. This is merely for ease and is in no way meant to be a limitation. Further, it will be understood that any of the elements and/or embodiments of the invention described can be rearranged, separated, and/or combined without deviating from the scope of the invention. For ease, various elements are described, at times, separately. This is merely for ease and is in no way meant to be a limitation. 
         [0077]    The separation of various system components in the examples described above should not be understood as requiring such separation in all examples, and it should be understood that the described components and systems can generally be integrated together in a single package into multiple systems and/or multiple components. It is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that the teachings may be applied in numerous applications, only some of which have been described herein. Unless otherwise stated, all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this specification, including in the claims that follow, are approximate, not exact. They are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain. 
         [0078]    Although the invention herein has been described with reference to particular implementations, it is to be understood that these are merely illustrative, to further assist persons of ordinary skill in understanding the present concepts to make and use embodiments thereof. It will also be apparent to such persons, upon reading this disclosure in its entirety that various modifications and variations can be made to the methods and apparatus as disclosed without departing from the spirit and scope of the invention. Thus, it is intended that the present invention include modifications and variations that are within the scope of the appended claims and their equivalents.