WO2025233936A1

WO2025233936A1 - Capnography filter

Info

Publication number: WO2025233936A1
Application number: PCT/IL2025/050376
Authority: WO
Inventors: Alon Sasson; Doron Lilo; Alexander RABKIN; Shai Fleischer; Denis GLOZMAN
Original assignee: Oridion Medical 1987 Ltd
Current assignee: Oridion Medical 1987 Ltd
Priority date: 2024-05-06
Filing date: 2025-05-05
Publication date: 2025-11-13
Anticipated expiration: 2026-11-06

Abstract

A capnography filter includes a housing with a filter insert portion, and a gas-permeable hydrophobic barrier. The housing may define a housing lumen extending therein. The filter insert portion may be positioned within and extend at least partially along the housing lumen. The housing and/or filter insert portion may include a moisture-impermeable material defining a filter insert lumen configured to receive exhalation introduced into the capnography filter and one or more channels configured to collect moisture or liquid from the exhalation. The gas-permeable hydrophobic barrier may be positioned within the housing lumen and configured to allow passage of dry gases from the exhalation through an outlet of the capnography filter and resist passage of the moisture or liquid.

Description

CAPNOGRAPHY FILTER

TECHNICAL FIELD

[0001] The present technology is generally related to capnography, particularly to nonabsorbent capnography filters that improve liquid capacity of the capnography filter and enable an efficient rise time of a capnography device.

BACKGROUND

[0002] Capnography is used to monitor exhalations from a patient, in particular, to determine carbon dioxide content in exhalations from the patient. Carbon dioxide concentration may differ at various stages of exhalation. Carbon dioxide concentration may also differ by physiological conditions associated with the patient. Capnography may be used by medical professionals to determine deviations from nominal exhalation characteristics of a patient. The patient may be intubated or non-intubated. For example, a capnography device may use one or more sensors to measure an amount of carbon dioxide in exhalations from the patient, for example, in-line sensors, or sensors in remote monitors. In addition, the capnography device may include one or more filters to remove any moisture, liquid, or contaminants from the exhalations that may affect accuracy of capnography measurements and/or that may affect components of the capnography device (e.g., sensors, monitors, electrical components).

SUMMARY

[0003] Certain embodiments commensurate in scope with the originally claimed subject matter are summarized below. These embodiments are not intended to limit the scope of the disclosure. Indeed, the present disclosure encompasses a variety of forms that may be similar to or different from the embodiments set forth below.

[0004] In an embodiment, a capnography system includes a sampling line that transfers the exhalation sample to a capnography monitor, and a capnography filter to filter the exhalation sample prior to the exhalation sample being received by the capnography monitor. The capnography filter includes a housing formed from a water non-absorbent material and defining a housing lumen extending from a first housing lumen end to a second housing lumen end. The housing also defines one or more channels within the housing lumen to receive a first portion of the exhalation sample. Furthermore, the capnography filter comprises a gas-permeable hydrophobic barrier extending across the second housing lumen end and such that a second portion of the exhalation sample flows across the gas-permeable hydrophobic barrier and through an outlet of the capnography filter.

[0005] In an embodiment, a capnography filter includes a housing defining a housing lumen extending therethrough and configured to receive an inlet tube that introduces an exhalation sample from a patient into the housing lumen, and one or more projection extending radially within the housing lumen. Moreover, the capnography filter includes a gas-permeable hydrophobic barrier extending across the housing lumen and allowing passage of dry gases from the exhalation sample to cross the gas-permeable hydrophobic barrier and exit the capnography filter.

[0006] Various refinements of the features noted above may exist in relation to various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. The brief summary presented above is intended only to familiarize the reader with certain aspects and context of embodiments of the present disclosure without limitation to the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Advantages of the disclosed techniques may become apparent upon reading the following detailed description and upon reference to the drawings in which:

[0008] FIG. 1 is a block diagram of an embodiment of a capnography system including a capnography filter, in accordance with an aspect of the present disclosure;

[0009] FIG. 2 is a cross-sectional schematic view of an embodiment of the capnography filter of FIG. 1, in accordance with an aspect of the present disclosure;

[0010] FIG. 3 is a cross-sectional schematic view of an embodiment of the capnography filter of FIG. 2 including one or more channels, in accordance to an aspect of the present disclosure; [0011] FIG. 4 is a cross-sectional schematic view of the embodiment of the capnography filter of FIG. 3 that includes the one or more channels, in accordance with an aspect of the present disclosure;

[0012] FIG. 5 is a cross-sectional schematic view of an embodiment of the capnography filter of FIG. 2 including one or more filter insert channels, in accordance with an aspect of the present disclosure;

[0013] FIG. 6 is a cross-sectional schematic view of the embodiment of the capnography filter of FIG. 5 that includes the one or more filter insert channels, in accordance with an aspect of the present disclosure;

[0014] FIG. 7 is a cross-sectional schematic view of an embodiment of the capnography filter of FIG. 2 including a filter insert with one or more rib projections forming two or more rib channels, in accordance with an aspect of the present disclosure;

[0015] FIG. 8 is a cross-sectional schematic view of the embodiment of the capnography filter of FIG. 7 that includes ten rib projections forming ten rib channels therebetween, in accordance with an aspect of the present disclosure;

[0016] FIG. 9 is a cross-sectional schematic view of the embodiment of the capnography filter of FIG. 7 that includes fourteen rib projections forming fourteen rib channels therebetween, in accordance with an aspect of the present disclosure;

[0017] FIG. 10 is a cross-sectional schematic view of the embodiment of the capnography filter of FIG. 7 that includes six rib projections forming six rib channels therebetween, in accordance with an aspect of the present disclosure;

[0018] FIG. 11 is a perspective schematic view of an embodiment of the capnography filter of FIG. 1 that includes a filter member, in accordance with an aspect of the present disclosure;

[0019] FIG. 12 is a cross-sectional schematic view of an embodiment of the capnography filter of FIG. 1 that includes two filter member portions, in accordance with an aspect of the present disclosure; [0020] FIG. 13 is a cross-sectional schematic view of an embodiment of the capnography filter of FIG. 1 that includes a filter member, in accordance with an aspect of the present disclosure;

[0021] FIG. 14 is a cross-sectional schematic view of the embodiment of the capnography filter of FIG. 13 that includes ten rib projections forming ten rib channels therebetween; and

[0022] FIG. 15 is a flow diagram of an embodiment of a method for filtering moisture and liquid from exhalation via a capnography filter.

DETAILED DESCRIPTION

[0023] One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementationspecific decisions must be made to achieve the developers’ specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0024] When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0025] In general, aspects of the present disclosure relate to capnography, and to filters for capnography. Exhalation (e.g., exhaled breath, breath sample) from a patient that is transferred to a capnography monitor may include moisture, liquid, or contaminants that may affect the accuracy of capnography and that may affect components of a capnography sensor or monitor. Capnography filters (e.g., capnography filtration devices, sampling line filters, filters) according to the present disclosure may be used to reduce or remove moisture, liquid, or contaminants from exhalation. For example, a capnography filter may be positioned in a path between a cannula or airway adapter and a capnography monitor that receives exhalation from a patient.

[0026] Typically, capnography filters may contain an absorbent material to remove moisture and/or liquids from the exhalation. However, using such absorbing materials may increase rise time of a measured signal at the capnography device and decrease accuracy of carbon dioxide concentration measurements (e.g., end-tidal CO2 measurements (ETCO2), fractional inspired CO2) of a patient.

[0027] With the foregoing in mind, the present disclosure relates to embodiments of capnography filter connectors without an absorbing medium and/or that include non-absorbent structures that can accommodate liquid or moisture without absorption. That is, in contrast to filter material that absorbs moisture from exhalation, the disclosed embodiments include connectors with non-absorbing channels, such as hollow fibers or other open spaces that can receive moisture. In some embodiments, the capnography filters disclosed herein may not include or be formed of any water-absorptive materials. Furthermore, the liquid capacity may, in embodiments, be related to the total volume of channels or open spaces to receive moisture. Such embodiments of capnography filters enable improved liquid capacity and improved rise times of associated capnography devices.

[0028] In particular, embodiments of the capnography filters according to the present disclosure may utilize capillary properties of fluids to remove moisture, liquids, and/or contaminants from exhalations of a patient without significantly impacting pneumatic properties of the capnography device. In addition, the capnography filters may include a simplified construction, thus reducing production cost and assembly complexity of the capnography filter. For example, a filtration device cross-sectional area along a length of the capnography filter may exhibit relatively low or no changes. This may reduce rise time as compared to other filters with cross-sectional areas that varies along a length of the respective filter.

[0029] Embodiments of the capnography filters according to the present disclosure may also provide constant pressure drop and rise time during usage. Additionally, during operation, contamination may not block the sampling line or increase pressure drop. It should be understood that varying sizes (e.g., lengths, diameters) of capnography fdters discussed herein may be used based on a target time of use or expected volume of exhalation over time.

[0030] Furthermore, the disclosed capnography fdters maintain a minimal rise time factor for a capnography fdterline while maximizing a fluid capacity of the fdtration devices at a reasonably high level. Rise time may be a time it takes for a capnography signal to increase from 10% to 90% of an overall, total, or final value of the capnography signal. Rise time may be influenced or distorted due to pneumatics of the capnography filter, including the pneumatics of the filter (e.g., any filter inserts) itself. Fluid capacity may be a maximum fluid amount or total fluid capacity of the capnography filter.

[0031] As such, certain characteristics of the capnography filter, for example, structure and/or arrangement of components of the filtration device, and features of the filtration device, for example hydrophobicity, density of the material, resistance to air penetration, internal structure, such as number of pores or vacancies, grade of interconnection between the pores or vacancies, etc., can also influence a respective capnography filter's performance. In particular, the structure of the internal components of the filter device may influence a maximum fluid capacity of the filter device, and thus affect a rise time associated with the capnography filter. Embodiments of the capnography filters disclosed herein may decrease rise time, while increasing fluid capacity of the capnography filter. In addition, in some embodiments, increasing fluid capacity of the capnography filter may extend the life of the capnography filter.

[0032] With the foregoing in mind, FIG. 1 is a block diagram of an embodiment of a capnography system 10 including a capnography filter 12. A cannula or airway adapter 14 may be positioned about or within a mouth or nasal cavity of a patient 16, or in an endotracheal tube, to receive exhalation (e.g., a breath sample) from the patient 16. The capnography filter 12 may be part of a capnography connector that includes ports or coupling points to transfer exhaled breath via a tube or sampling line 18 to a capnography monitor or module 20. The capnography monitor or module 20 may include one or more sensors 22 to detect (e.g., measure) a substance, such as carbon dioxide and/or other gases in the exhalation from the patient 16. The capnography filter 12 may be coupled in-line within the sampling line 18, or between the sampling line 18 and the capnography monitor or module 20. The capnography filter 12 is configured to reduce or remove moisture, liquids, or contamination, from the exhalation, such that substantially only dried gases portion of the exhalation is received by the capnography monitor or module 20 (e.g., the one or more sensors 22). [0033] FIG. 2 is a cross-sectional schematic view of an embodiment of the capnography filter 12 of FIG. 1, in accordance with an aspect of the present disclosure. The following description of FIGS. 2-14 is with reference to axes 30, which includes a vertical axis 32, a longitudinal axis 34, and a lateral axis 36 (e.g., extending vertically from the page). A crosssection of the capnography filter 12 of FIG. 2 is taken through a central housing axis 38 along a direction substantially parallel to the longitudinal axis 34 from a first filter end 40 (e.g., first housing end) to a second filter end 42 (e.g., second housing end). In some embodiments, the central housing axis 38 is a central longitudinal axis of the capnography filter 12. The capnography filter 12 includes a housing 44 (e.g., filter body, filter chamber), a filter insert 46, and a gas-permeable hydrophobic barrier 48 (e.g., gas-permeable hydrophobic membrane). The housing 44 defines a housing lumen 50 extending from the first filter end 40 to the gas- permeable hydrophobic barrier 48. In particular, the housing lumen 50 may extend from a first housing lumen end 52 (e.g., inlet) to a second housing lumen end 54 (e.g., outlet). In some embodiments, the first housing lumen end 52 may correspond to a same position along a length 56 of the housing 44 as a position of the first filter end 40. In addition, in some embodiments, the second housing lumen end 54 may be at a position along the length 56 of the housing 44 that is not a same position as the second filter end 42. In other words, a length 58 of the housing lumen 50 may be less than the length 56 of the housing 44. The housing lumen 50 may be any suitable size and/or shape, for example, a cylindrical lumen.

[0034] In addition, the housing 44 may define an inlet 60 configured to receive exhalation sample from a patient and/or enable an exhalation sample to be introduced into (e.g., introduced interior to, inside of) the housing lumen 50 of the capnography filter 12. In some embodiments, the inlet 60 may be configured to receive an inlet tube 62 (e.g., tube or sampling line 18) that introduces or transfers an exhalation sample into the capnography filter 12. Exhalation (e.g., an exhaled breath sample) may be introduced to (e.g., enter) the capnography filter 12 through the inlet 60 and into the housing lumen 50 (e.g., into the first housing lumen end 52), and may generally be directed to flow in a flow direction 64 from the first filter end 40 to second filter end 42. Furthermore, the gas-permeable hydrophobic barrier 48 may at least partially cover or extend across the second housing lumen end 54 of the housing lumen 50.

[0035] The housing 44 may also define one or more chambers (e.g., lumens) positioned downstream of the gas-permeable hydrophobic barrier 48, with respect to the flow direction 64 of an exhalation sample. The one or more chambers may include a first outlet chamber 66 fluidly coupled to the housing lumen 50. A portion of the exhalation sample (e.g., the dry gasses portion) may cross the gas-permeable hydrophobic barrier 48 and enter the first outlet chamber 66. The first outlet chamber 66 may be any suitable size and/or shape, for example, a conical chamber. The one or more chambers may include a second outlet chamber 68. The second outlet chamber 68 may be fluidly coupled to the first outlet chamber 66 and configured to receive the portion of the exhalation sample that crossed the gas-permeable hydrophobic barrier 48. In some embodiments, a size and/or shape of the second outlet chamber 68 may be different than a size and/or shape of the first outlet chamber 66. For example, in the illustrated embodiment, the second outlet chamber 68 is a cylindrical chamber. It should be appreciated that the second outlet chamber 68 may be any suitable size and/or shape. Furthermore, the one or more chambers may include a third outlet chamber 70. The third outlet chamber 70 may be fluidly coupled to the first outlet chamber 66 and the second outlet chamber 68 and configured to receive the portion of the exhalation sample that crossed the gas-permeable hydrophobic barrier 48. In some embodiments, a size and/or shape of the third outlet chamber 70 may be different than a size and/or shape of the first outlet chamber 66 and/or the second outlet chamber 68. For example, in the illustrated embodiment, the third outlet chamber 70 is a cylindrical chamber with a diameter 71 that is greater than a diameter 73 of the second outlet chamber 68. It should be appreciated that the third outlet chamber 70 may be any suitable size and/or shape. For example, in some embodiments, the third outlet chamber 70 may comprise a conical shape with a diameter that increases along the length of the third outlet chamber 70 (e.g., extending towards the second filter end 42). In some embodiments, a shape of the outlet chamber 70 may facilitate pneumatic coupling of the capnography filter 12 to a port of the capnography monitor or module 20.

[0036] Moreover, the housing 44 may define an outlet 72. In particular, the outlet 72 may enable a filtered portion of the exhalation sample to exit the capnography filter 12. The outlet 72 may comprise an outlet of the third outlet chamber 70. As discussed herein, the capnography filter 12 may be coupled to the capnography monitor or module 20. As such, the outlet 72 may enable a portion of the exhalation sample (e.g., the filtered portion, the dry gases portion) to be received by the sensor 22 of the capnography monitor or module 20.

[0037] In some embodiments, the first filter end 40 may define the inlet 60 while the second filter end 42 may define the outlet 72. In other words, the inlet 60 and/or the outlet 72 may be integrally formed with the housing 44. One or both of the inlet 60 or the outlet 72 may include an opening having any suitable shape or size, for example, a circular opening.

[0038] The housing 44 may define or include one or more threads 74 to enable the capnography filter 12 to couple to a port of the capnography monitor or module 20. Additionally, in some embodiments, the housing 44 may define or include one or more ridges 76 (e.g., projections, rims, lips) extending out from the central housing axis 38. The one or more ridges 76 may facilitate coupling of the capnography filter 12 to the port of the capnography monitor or module 20. In particular, the one or more ridges 76 may enable a rotational force to be applied to the one or more ridges 76 to mechanically couple the capnography filter 12 to the port.

[0039] The housing 44 may have any suitable shape. For example, the housing 44 may be elongated and tubular. In some embodiments, a wall of the housing 44 is formed by a portion of tubing. In some embodiments, the housing 44 has a substantially circular cross-section taken along the lateral axis 36.

[0040] The housing 44 may include or be formed by any suitable rigid or soft material. For example, the housing 44 may be rigid and resist deformation, or may be flexible or soft and permit deformation. In some embodiments, the housing 44 includes one or more polymeric material. The housing 44 may be transparent or translucent to permit visual inspection of an interior of the housing 44 (e.g., visual inspection of contents within the housing lumen 50), for example, to ascertain a condition of components positioned within the housing lumen 50.

[0041] Continuing with FIG. 2, the capnography filter 12 may include the filter insert 46 configured to be positioned within the housing lumen 50. The filter insert 46 is positioned in the housing lumen 50 and extends at least partially along the housing lumen 50. For example, the filter insert 46 may be coextensive with the housing lumen 50 or may partially extend with the housing lumen 50. In some embodiments, the filter insert 46 extends along the entire length 58 of the housing lumen 50, for example, from the first housing lumen end 52 to the second housing lumen end 54. In other embodiments, the filter insert 46 extends along a portion of the length 58 of the housing lumen 50. It should be appreciated that, in some embodiments, the filter insert 46 may be separate (e.g., a separate component or piece) from the housing 44 of the capnography filter 12. In other embodiments, the filter insert 46 may be integrated with or at least partially integrated with the housing 44. For example, the filter insert 46 and the housing 44 may be formed of a single continuous piece of material. In such embodiments, the housing lumen 50 may be substantially defined as or the same as the filter insert lumen 78. In addition, the filter insert 46 may have any suitable shape, for example, a shape conforming to a shape of the housing lumen 50. In some embodiments, the filter insert 46 is tubular (e.g., circular with a hollow space extending therethrough). In some embodiments, at least a portion of an outer surface of the filter insert 46 is in contact with an inner surface of the housing 44. In other embodiments, the outer surface of the filter insert 46 may be spaced a distance apart from and/or form a gap (e.g., space, void) between the inner surface of the housing 44 and the outer surface of the filter insert 46.

[0042] In some embodiments, the filter insert 46 includes or is formed at least partially of a moisture-impermeable material that does not absorb moisture and defines a filter insert lumen 78. The moisture -impermeable material may be any suitable material that tends to resist absorption of moisture or liquid. The moisture-impermeable material may include a natural or synthetic medium. In some embodiments, the moisture-impermeable material may include one or more polymeric substances configured to resist absorption of moisture and liquid from an exhalation sample. In some embodiments, the moisture-impermeable material may include non-absorbing beads or particulates dispersed in a non-absorbing matrix. In an embodiment, the moisture-impermeable material as provided herein is a material with a surface that, using a water drop static contact angle measurement, has a measured contact angle at least 15 degrees smaller than that of the gas-permeable hydrophobic barrier 48. In embodiments, the filter insert 46 may be formed from a material that is resistant to absorption of moisture in the exhaled breath. In an embodiment, the filter insert 46 is formed from a dimensionally stable thermoplastic. In an embodiment, the filter insert 46 is formed from a material which is significantly less hydrophobic than the gas-permeable hydrophobic barrier 48 material, including hydrophobic materials which had been surface-treated to decrease hydrophobicity.

[0043] In some examples, the moisture-impermeable material of the filter insert 46, and, therefore, the filter insert 46 in some cases, is relatively flexible. In other embodiments, the moisture-impermeable material of the filter insert 46, and, therefore, the filter insert 46 is relatively rigid. The relatively rigid characteristic of the filter insert 46 may facilitate engagement with or positioning of the inlet tube 62 within the housing lumen 50 (e.g., the filter insert lumen 78), while resisting bending or kinking of the inlet tube 62. In particular, the filter insert lumen 78 may be configured to receive a distal end of the inlet tube 62, and thus receive an exhalation sample introduced into the capnography filter 12. Moisture or liquid from the exhalation sample may pass along the inlet tube 62 and into (e.g., along, within) the filter insert lumen 78.

[0044] In some embodiments, the capnography filter 12 includes a plug 80, for example, at the first filter end 40. The plug 80 may be closely fitted within the housing lumen 50, such that the plug 80 blocks all flow of exhalation samples past and through the plug 80 (e.g., prevent flow of exhalation from exiting the housing lumen 50 at the first filter end 40). The plug 80 may define the inlet 60 (e.g., opening of the inlet 60). The plug 80 may include or be formed of any suitable material that blocks flow of gas, moisture, and liquid. In the illustrated embodiment, the plug 80 interfaces with (e.g., contacts) and/or surrounds (e.g., concentrically surrounds) the filter insert 46. Additionally, a portion of the plug 80 interfaces with the inner surface of the housing wall that defines the housing lumen 50. For example, in some embodiments, the filter insert 46 may extend along a portion of the length 58 of the housing lumen 50, and the plug 80 may extend along the entire length 58 of the housing lumen 50. In such embodiments, the plug 80 may define a plug lumen 82 configured to receive and/or surround the inlet tube 62, the filter insert 46, or both. In other embodiments, the plug 80 may not be present, and the housing 44 may integrally define an end wall at the first filter end 40.

[0045] In some embodiments, the capnography filter 12 includes an interior gap 84, for example, positioned or formed distal to the distal end of the inlet tube 62. For example, the inlet tube 62 may extend within the filter insert lumen 78 of the filter insert 46. In particular, the inlet tube 62 is configured to be positioned within the filter insert lumen 78 such that the gap 84 is formed. For example, the inlet tube 62 may extend at least partially along a length 86 of the filter insert 46 and within the filter insert lumen 78. In the illustrated example, at one end, the inlet tube 62 may extend beyond the filter insert 46 (e.g., within the housing lumen 50). In particular, as discussed above, a portion of the inlet tube 62 may extend within the plug lumen 82. Furthermore, at an opposite end, the inlet tube 62 may extend within the filter insert lumen 78 to a position along the length 86 of the filter insert 46 to form the gap 84. In addition, a portion of the filter insert 46 may extend from the position to the gas-permeable hydrophobic barrier 48. As such, the gap 84 may be formed within the filter insert lumen 78.

[0046] Moreover, in some embodiments, the capnography filter 12 may include one or more components that cause or facilitate positioning of the inlet tube 62 such that the gap 84 is formed. In some embodiments, the filter insert 46 may facilitate positioning of the inlet tube 62 such that the gap 84 is formed. A distal end or opening 88 of the inlet tube 62 may be spaced a distance 63 apart from the gas-permeable hydrophobic barrier 48. In addition, a wall of the inlet tube 62 may act as a barrier to flow of exhalation across the wall of the inlet tube 62, such that exhalation flows toward the distal end or distal opening 88 of the inlet tube 62 (e.g., towards the second fdter end 42) and flows into the interior gap 84 or space formed between the distal opening 88 of the inlet tube 62 and the gas-permeable hydrophobic barrier 48. In particular, an exhalation sample may thus flow in the flow direction 64 through and along the inlet tube 62, and the exhalation sample (e.g., including any wet gases and/or liquids) may be directed to or flow into the gap 84 prior to a portion of the exhalation sample (e.g., the dry gases) flowing across the gas-permeable hydrophobic barrier 48 and towards the outlet 72. In some embodiment, the gap 84 may collect (e.g., hold, store) moisture and/or liquids from the exhalation sample.

[0047] Furthermore, the capnography fdter 12 includes the gas-permeable hydrophobic barrier 48 (e.g., gas-permeable hydrophobic membrane). The gas-permeable hydrophobic barrier 48 is configured to help reduce or even prevent moisture and/or liquids from entering the capnography monitor or module 20 and/or the sensor 22, and, in some embodiments, also acts as a barrier for microorganisms, for example, bacteria. In particular, the gas-permeable hydrophobic barrier 48 is positioned to allow passage of gases (e.g., dry gases, from exhalation) from the filter insert lumen 78 (e.g., from the gap 84) and through the outlet 72 of the capnography filter 12 and resist passage of moisture and liquid across the gas-permeable hydrophobic barrier 48. In the illustrated embodiment, the gas-permeable hydrophobic barrier 48 may at least partially cover or extend across the housing lumen 50 (e.g., and the filter insert lumen 78).

[0048] For example, the gas-permeable hydrophobic barrier 48 may be fluidly coupled to the housing lumen 50. In some embodiments, the gas-permeable hydrophobic barrier 48 may be positioned within the housing lumen 50, such that an inner surface of the housing wall that defines the housing lumen 50 contacts an edge of the gas-permeable hydrophobic barrier 48. Alternatively, in some embodiments, the gas-permeable hydrophobic barrier 48 may be positioned adjacent to the housing lumen 50, such that an end of the housing wall defining the housing lumen 50 contacts an inner face of the gas-permeable hydrophobic barrier 48. In some embodiments, the gas-permeable hydrophobic barrier 48 may be positioned between the first and second filter ends 40 and 42. In particular, the gas-permeable hydrophobic barrier 48 is positioned between the filter insert 46 and the first outlet chamber 66. [0049] The gas-permeable hydrophobic barrier 48 may have any suitable shape. For example, a periphery or edge of the gas-permeable hydrophobic barrier 48 may follow an internal surface of the housing lumen 50, or an outer surface of the filter insert 46. The shape and size of the gas-permeable hydrophobic barrier 48 may substantially conform to one or both of the housing lumen 50 or the filter insert 46. In some examples, the gas-permeable hydrophobic barrier 48 is shaped as a disc.

[0050] In some embodiments, the gas-permeable hydrophobic barrier 48 is positioned to extend transverse (e.g., crosswise) to the length 58 of the housing lumen 50. In some embodiments, the gas-permeable hydrophobic barrier 48 may be inclined at any predetermined angle relative to the central housing axis 38 of the housing 44 extending along a direction from the first filter end 40 to the second filter end 42. In some embodiments, the gas-permeable hydrophobic barrier 48 is perpendicular to the central housing axis 38. In some embodiments, the gas-permeable hydrophobic barrier 48 extends across the second housing lumen end 54, as illustrated in FIG. 2. However, the gas-permeable hydrophobic barrier 48 may be spaced a distance apart from the second housing lumen end 54, for example, if an end of the filter insert 46 is spaced a distance apart from the second housing lumen end 54. For example, the filter insert 46 may extend from a first filter insert end facing the first filter end 40 to a second filter insert end facing the second filter end 42, and the gas-permeable hydrophobic barrier 48 may extend across the second filter insert end of the filter insert 46. Thus, the gas-permeable hydrophobic barrier 48 may contact one, both, or none, of the second filter insert end or the second housing lumen end 54. In some examples, the gas-permeable hydrophobic barrier 48 contacts each of the second filter insert end of the filter insert 46 and the second housing lumen end 54.

[0051] One or more portions, or an entirety, of the gas-permeable hydrophobic barrier 48 may be substantially flat, angled, or curved. The gas-permeable hydrophobic barrier 48 may have any suitable thickness. The gas-permeable hydrophobic barrier 48 may be corrugated or assume a shape that facilitates increasing a ratio of surface area to volume of the gas-permeable hydrophobic barrier 48.

[0052] In some examples, the gas-permeable hydrophobic barrier 48 includes or is at least partially formed of a porous hydrophobic membrane, for example, a porous hydrophobic polymeric membrane. In some examples, a pore size of the gas-permeable hydrophobic barrier 48 is, on average, 0.1 microns to 0.2 microns, but can have other average pore sizes in other examples. Such a membrane may facilitate blocking or preventing bacteria or viruses from traversing the gas-permeable hydrophobic barrier 48 and travelling downstream towards the capnography monitor or module 20.

[0053] The configuration of the capnography filter 12, as well as other filtration devices described herein, enables the capnography filters to be relatively easily modified to accommodate different intended times of use. For example, a length (e.g., length 56) of the capnography filter 12 (measured along the central housing axis 38), and/or, in some embodiments, a length (e.g., length 86) of the filter insert 46, can be increased to accommodate longer intended duration of use. A clinician can select from a plurality of different length capnography filters based on the intended duration of use with a patient.

[0054] While a single filter insert 46 and single gas-permeable hydrophobic barrier 48 are described with reference to FIGS. 2-10, example capnography filters may include more than one filter member, or more than one gas-permeable hydrophobic barrier. For example, a first gas-permeable hydrophobic barrier may be positioned between two distinct filter inserts along the housing lumen, and a second gas-permeable hydrophobic barrier may be positioned at or adjacent an end of one of the filter inserts.

[0055] In some embodiments, the inlet tube 62 may be configured to be spaced a distance apart from an inner surface of the filter insert 46 that forms the filter insert lumen 78, as further described below with reference to FIG. 3.

[0056] FIG. 3 is a cross-sectional schematic view of an embodiment of the capnography filter 12 of FIG. 2 including one or more channels 200, in accordance to an aspect of the present disclosure. In particular, the inlet tube 62 is positioned within the filter insert lumen 78 such that one or more channels 200 (e.g., conduits, passages) are formed between the filter insert 46 (e.g., an inner surface 202 of the filter insert 46 that defines the filter insert lumen 78) and an outer surface 204 of the inlet tube 62. For example, a diameter of the filter insert lumen 78 may be greater than an outer diameter of the inlet tube 62. In addition, the inner surface 202 of the filter insert 46 may be spaced a distance 203 apart from the outer surface 204 of the inlet tube 62 to form a gap (e.g., space, void) between the inner surface 202 of the filter insert 46 and the outer surface 204 of the inlet tube 62. Thus, a space or circular channel is formed within the filter insert lumen 78 that surrounds the inlet tube 62.

[0057] The one or more channels 200 may increase a liquid capacity of the capnography filter 12 as compared to a capnography filtrations device that may not include the one or more channels 200. To this end, the moisture and/or liquids from an exhalation sample (e.g., a portion of an exhalation sample) may first flow from the distal end or opening 88 of the inlet tube 62 (e.g., flow along a inlet tube lumen 208) and into the interior gap 84. Then, due to the adhesion and/or cohesion properties of the moisture and/or liquids (e.g., water), the moisture and/or liquids collected within the gap 84 may be directed to flow in a flow direction 206 (e.g., opposite the flow direction 64 of the exhalation sample through or along the inlet tube 62) along the one or more channels 200 (e.g., via capillary action) and away from the gas-permeable hydrophobic barrier 48. As such, the capnography filter 12 that includes the one or more channels 200 may collect the moisture and/or liquids from exhalation samples within the one or more channels 200 and enable a portion of the exhalation sample (e.g., the dry gases, a filtered portion) cross the gas-permeable hydrophobic barrier 48 and flow towards the outlet 72 of the capnography filter 12 (e.g., towards the capnography monitor or module 20).

[0058] FIG. 4 is a cross-sectional schematic view of the embodiment of the capnography filter 12 of FIG. 3 that includes the one or more channels 200, in accordance to an aspect of the present disclosure. In particular, the cross-sectional view of FIG. 4 is taken through crosssection line A-A illustrated in FIG. 3. As illustrated, the positioning of the inlet tube 62 within the filter insert lumen 78 and the diameter 210 of the filter insert lumen 78 is greater than an outer diameter 212 of the inlet tube (e.g., the , which forms a space or circular channel (e.g., the one or more channels 200) that surrounds the inlet tube 62 and is between the inner surface 202 of the filter insert 46 and the outer surface 204 of the inlet tube 62. It should be understood that the one or more channels 200 can comprise any suitable shape, such as, for example, substantially circular or ring shaped.

[0059] In some embodiments, the filter insert 46 may include one or more filter insert channels formed within a body of the filter insert 46 and configured to collect or store (e.g., draw) moisture and/or liquid portion of an exhalation sample from the gap 84, as further described below with reference to FIG. 5.

[0060] FIG. 5 is a cross-sectional schematic view of an embodiment of the capnography filter 12 of FIG. 2 including one or more filter insert channels 300, in accordance to an aspect of the present disclosure. In particular, the filter insert 46 may include one or more filter insert channels 300 formed within a body 302 of the filter insert 46. For example, the filter insert 46 may be formed or configured such that the one or more filter insert channels extend from a first filter insert end 304 of the filter insert 46 and towards a second filter insert end 306 in a direction substantially parallel to the central housing axis 38 of the capnography filter 12. In some embodiments, the one or more filter insert channels 300 may extend partially along the length 86 of the filter insert 46. In other embodiments, the one or more channels 300 may extend along an entire length 86 of the first insert 46. In such embodiments, the filter insert 46 may be formed of two distinct (e.g., separate) portions or components concentrically arranged or coupled to form the one or more filter channels between the distinct portions. In addition, a distal opening 308 of the one or more filter insert channels 300 may be fluidly coupled to the gap 84 (e.g. the filter insert lumen 78).

[0061] The one or more filter insert channels 300 may increase a liquid capacity of the capnography filter 12 as compared to a capnography filtrations device that may not include the one or more filter insert channels 300. To this end, the moisture and/or liquids from an exhalation sample (e.g., a portion of an exhalation sample) may first flow from the distal end or opening 88 of the inlet tube 62 (e.g., flow along an inlet tube lumen 208) and into the interior gap 84. Then, due to the adhesion and/or cohesion properties of the moisture and/or liquids (e.g., water), the moisture and/or liquids collected within the gap 84 may flow in flow directions 310 that extend radially outwards from the central housing axis 38 towards the one or more filter insert channels 300. The moisture and/or liquids then may be directed to flow in a flow direction 312 (e.g., opposite the flow direction 64 of the exhalation sample through or along the inlet tube 62) along the one or more filter insert channels 300 (e.g., via capillary action) and away from the gas-permeable hydrophobic barrier 48. As such, the capnography filter 12 that includes the one or more filter insert channels 300 may collect or store the moisture and/or liquids from exhalation samples within the one or more filter insert channels 300 and enable a portion of the exhalation sample (e.g., the dry gases, a filtered portion) cross the gas-permeable hydrophobic barrier 48 and flow towards the outlet 72 of the capnography filter 12 (e.g., towards the capnography monitor or module 20).

[0062] FIG. 6 is a cross-sectional schematic view of the embodiment of the capnography filter 12 of FIG. 5 that includes the one or more filter insert channels 300, in accordance to an aspect of the present disclosure. In particular, the cross-sectional view of FIG. 6 is taken through cross-section line B-B illustrated in FIG. 5. As illustrated, the one or more filter insert channels 300 are formed between a first portion 314 of the filter insert 46 and a second portion 316 of the filter insert 46, the first portion 314 concentrically surrounding the inlet tube 62 and the second portion 316 concentrically surrounding the one or more filter insert channels 300. In particular, the inner surface 318 of the second portion 316 of the filter insert 46 may be spaced a distance 317 apart from the outer surface 320 of the first portion 314 of the filter insert 46 to form a gap (e.g., space, void) between the inner surface 318 of the second portion 316 of the filter insert 46 and the outer surface 320 of the first portion 314 of the filter insert 46. Thus, a space or circular channel (e.g., the one or more filter insert channels 300) is formed within the filter insert 46 that surrounds the first portion 314 of the filter insert 46. It should be understood that the one or more filter insert channels 300 can comprise any suitable shape, such as, for example, substantially circular or ring-shaped.

[0063] In some embodiments, the inlet tube 62 may be configured to be spaced a distance apart from an inner surface of the filter insert 46 that forms the filter insert lumen 78. In addition, the filter insert 46 may include one or more projections (e.g., rib projections, ridges, peaks, points) that extend (e.g., lengthwise) along a length of the filter insert and form two or more filter insert channels (e.g., rib channels) between the one or more projections, as further described below with reference to FIG. 7. Such embodiments may increase or maximize a fluid capacity of the filtration device while maintaining a relatively low rise time.

[0064] FIG. 7 is a cross-sectional schematic view of an embodiment of the capnography filter 12 of FIG. 2 including a filter insert 46 with one or more rib projections 400 forming two or more rib channels 402 extending along a length 86 of the filter insert 46, in accordance to an aspect of the present disclosure. In the illustrated embodiment, the inlet tube 62 is positioned within the filter insert lumen 78 such that the inlet tube 62 is spaced a distance apart from an inner surface 404 of the filter insert 46. In addition, the filter insert 46 includes one or more rib projections 400 (e.g., ridges, points) extending into the filter insert lumen 78. Specifically, each of the one or more rib projections 400 may extend or protrude (e.g., project, jut) in a substantially radial direction towards the central housing axis 38. Each of the one or more rib projections 400 is positioned circumferentially around the filter insert lumen 78 (e.g., positioned around an inner circumference of the filter insert 46 forming the filter insert lumen 78) and spaced a distance (e.g., angular distance with respect to the central housing axis 38) apart from an adjacent respective rib projection 400. To this end, each rib channel 402 (e.g., each filter insert channel) is formed or defined between each two adjacent rib projections 400. Furthermore, in some embodiments, each of the one or more rib projections 400 may extend (e.g., lengthwise) along an entire length 86 of the filter insert 46. As such, the two or more rib channels 402 formed by the one or more rib projections 400 may additionally extend along an entire length 86 of the filter insert 46. In some embodiment, the one or more rib projections 400 may facilitate positioning of the inlet tube 62 within the filter insert lumen 78. In such embodiments, each of or a portion of the one or more rib projections 400 may contact (e.g., interface, touch) the outer surface of the inlet tube 62. [0065] The one ormore rib projections 400 (e.g., forming the two or more rib channels 402) may increase a liquid capacity of the capnography filter 12 as compared to a capnography filtrations device that may not include the one or more rib projections 400 of the filter insert 46. To this end, the moisture and/or liquids from an exhalation sample (e.g., a portion of an exhalation sample) may first flow from the distal end or opening 88 of the inlet tube 62 (e.g., flow along an inlet tube lumen 208) and into the interior gap 84. Then, due to the adhesion and/or cohesion properties and/or internal volume surface tension of the moisture and/or liquids (e.g., water), the moisture and/or liquids collected within the gap 84 may be directed to flow in a flow direction 406 (e.g., opposite the flow direction 64 of the exhalation sample through or along the inlet tube 62) along the two or more rib channels 402 (e.g., via capillary action) and away from the gas-permeable hydrophobic barrier 48. As such, the capnography filter 12 that includes the one or more rib projections 400 (e.g., forming the two or more rib channels 402) may collect the moisture and/or liquids from exhalation samples within the two or more rib channels 402 and enable a portion of the exhalation sample (e.g., the dry gases, a filtered portion) cross the gas-permeable hydrophobic barrier 48 and flow towards the outlet 72 of the capnography filter 12 (e.g., towards the capnography monitor or module 20).

[0066] FIG. 8 is a cross-sectional schematic view of the embodiment of the capnography filter 12 of FIG. 7 that includes ten rib projections 400 forming ten rib channels 402 therebetween, in accordance to an aspect of the present disclosure. In particular, the cross- sectional view of FIG. 7 is taken through cross-section line C-C illustrated in FIG. 7. As illustrated, the inlet tube 62 is configured to be positioned within the filter insert lumen 78 such that a space (e.g., gap) is formed between the outer surface 204 of the inlet tube 62 and the filter insert 46. In addition, as discussed above, the filter insert 46 includes the one or more rib projections 400 that extend substantially radially towards the housing central axis 38. In particular, the inner surface 404 of the filter insert 46 may comprise or form a series of alternating valleys 408 and peaks 410 to form the one ormore rib projections 400. For example, the valleys 408 (e.g., a minimum point or trough of the valley) may be positioned at a distance 412 (e.g., radial distance) from the central housing axis 38 that is greater than a distance 414 (e.g., radial distance) at which the peaks 410 (e.g., a maximum point or apex of the peaks) are positioned from or relative to the central housing axis 38. As such, the one or more rib projections 400 form the two or more rib channels 402. As illustrated, the filter insert 46 includes ten rib projections 400 forming ten rib channels 402 arranged concentrically surrounding the inlet tube 62 within the filter insert lumen 78. [0067] It should be understood that the one or more rib projections 400 (e.g., and thus the two or more rib channels 402 formed therebetween) may comprise any suitable shape, such as, for example, substantially triangular, triangular prism, cylinder, or trapezoidal prism in shape. Additionally, the filter insert 46 may comprise any suitable number of rib projections 400 (e.g., 2, 4, 8, 16, 20). In some embodiments, the rib projections 400 may be equally spaced around the inner surface 404 of the filter insert 46. It should be appreciated that each of the rib projections 400 may be spaced around the inner surface 404 of the filter insert 46 in any suitable position and/or spacing such that desired shape and size of rib channels 402 are formed therebetween. Furthermore, the one or more rib projections 400 may be of any suitable length (e.g., from outer surface of the filter insert and extending to the maximum point or peak of the projection). For example, each of the one or more projections 400 may be of a same length, or, in some embodiments, a portion of the one or more projections 400 may have a different (e.g., greater or lesser) than another portion of the one or more projections 400. Additionally, the one or more projections 400 may be of any suitable thickness and/or shape. For example, in some embodiments, each of the one or more projections 400 may taper in thickness starting from a first end of the projection proximate the outer surface of the filter insert 46 and extending towards a second end of the projection (e.g., the maximum point or peak; point distal from the outer surface of the filter insert 46). Alternatively, a portion or an entirety of the one or more projections 400 may each have a same or consistent thickness from the first end of the projection to the second end of the projection. It should be appreciated that a design, shape, and/or dimensions of the one or more rib projections 400 forming the two or more rib channels 402 may be selected such that the two or more rib channels 402 draw or attract moisture away from the gas-permeable hydrophobic barrier 48 or away from the gap 84 (e.g., by capillary force).

[0068] With the foregoing in mind, FIG. 9 is a cross-sectional schematic view of the embodiment of the capnography filter 12 of FIG. 7 that includes fourteen rib projections 400 forming fourteen rib channels 402 therebetween, in accordance to an aspect of the present disclosure. In particular, the cross-sectional view of FIG. 7 is taken through cross-section line C-C illustrated in FIG. 7.

[0069] As another example, FIG. 10 is a cross-sectional schematic view of the embodiment of the capnography filter 12 of FIG. 7 that includes six rib projections 400 forming six rib channels 402 therebetween, in accordance to an aspect of the present disclosure. In particular, the cross-sectional view of FIG. 7 is taken through cross-section line C-C illustrated in FIG. 7. [0070] FIG. 11 is a perspective schematic view of an embodiment of the capnography filter 12 of FIG. 1, in accordance with an aspect of the present disclosure. The following description of the capnography filter 12 of FIGS. 11-14 is directed to an embodiment of the capnography filter 12 with reference to FIGS. 1-10 that includes a filter member 403 (shown in FIGS. 12- 14). The filter member 403 may include or be composed of an absorbent material (e.g., medium) that absorbs (e.g., collects, traps, draws) moisture and/or liquid, such as moisture contained within and thus collected from an exhalation of a patient. In some embodiments, the filter member 403 may be composed of two or more portions (e.g., distinct materials, fibers). In some embodiments, the filter member 403 may be a high capacity absorber, such that it may be able to absorb an increased volume of moisture relative to arrangements without the filter member 403 before reaching a point of saturation. As such, in some embodiments, the filter member 403 may extend a life of the filter by extending use time for the capnography filter and increasing a time between changing a saturated capnography filter for a new capnography filter.

[0071] Similarly to embodiments described in FIGS. 1-10, the capnography filter 12 of FIGS. 11-14 includes the central housing axis 38 along a direction substantially parallel to the longitudinal axis 34 from the first filter end 40 (e.g., first housing end) to the second filter end 42 (e.g., second housing end). FIGS. 12 and 13 are cross-sectional schematic views of respective embodiments of the capnography filter 12 of FIG. 1, in accordance with an aspect of the present disclosure. In particular, a cross-section of the capnography filter 12 of FIGS. 12 and 13 is taken through the central housing axis 38 along a direction substantially parallel to the longitudinal axis 34 from the first filter end 40 (e.g., first housing end) to the second filter end 42 (e.g., second housing end). For conciseness, the respective embodiments of the capnography filter 12 of FIGS. 12 and 13 will be described together. The capnography filter 12 also includes the housing 44 (e.g., filter body, filter chamber), the filter insert 46, the filter member 403, and the gas-permeable hydrophobic barrier 48 (e.g., gas-permeable hydrophobic membrane). The housing 44 defines the housing lumen 50 extending from the first filter end 40 to the gas-permeable hydrophobic barrier 48. In addition, the housing 44 may define the inlet 60 configured to receive an exhalation sample from a patient and/or enable an exhalation sample to be introduced into (e.g., introduced interior to, inside of) the housing lumen 50 of the capnography filter 12. In particular, in some embodiments, the inlet 60 may be configured to receive the inlet tube 62 (e.g., tube or sampling line 18) that introduces ortransfers an exhalation sample into the capnography filter 12. Exhalation (e.g., an exhaled breath sample) may be introduced to (e.g., enter) the capnography filter 12 through the inlet 60 and into the housing lumen 50, and may generally be directed to flow in the flow direction 64 from the first filter end 40 to second filter end 42.

[0072] The filter insert 46 may be formed at least partially of a moisture-impermeable material that does not absorb moisture. In some embodiments, as illustrated in FIG. 12, the filter insert 46 may be positioned within the capnography filter 12 such that the one or more channels 200 may be at least partially formed between the filter insert 46 and the filter member 403 (e.g., a portion of the filter member 403). In some embodiments, as illustrated in FIG. 13, the filter insert 46 may be positioned within the capnography filter 12 such that the one or more channels 200 (e.g., conduits, passages) are formed between the filter insert 46 and the outer surface 204 of the inlet tube 62. In either embodiment, the one or more channels 200 may be formed within the filter insert lumen 78 and surround the inlet tube 62 and/or the filter member 403. To this end, the moisture and/or liquids from an exhalation sample (e.g., a portion of an exhalation sample) may first flow from the distal end or opening 88 of the inlet tube 62 (e.g., flow along the inlet tube lumen 208) and into the interior gap 84. Then, due to the adhesion and/or cohesion properties of the moisture and/or liquids (e.g., water), the moisture and/or liquids collected within the gap 84 may flow in the flow direction 206 (e.g., opposite the flow direction 64 of the exhalation sample through or along the inlet tube 62) along the one or more channels 200 (e.g., via capillary action) and away from the gas-permeable hydrophobic barrier 48. In some embodiments, as illustrated in FIG. 12, the moisture and/or liquids collected within the gap 84 may be absorbed by a first portion 405 of the filter member 403 (e.g., first fiber) prior to being directed towards the one or more channels 200 and/or to a second portion 407 of the filter member 403. In some embodiments, as illustrated in FIG. 13, the moisture and/or liquids collected within the gap 84 may be directed, via the one or more channels 200, to the filter member 403. In either embodiment, the moisture and/or liquids may be ultimately directed to and collected by filter member 403 (e.g., or the second portion 407 of the filter member 403) via the one or more channels 200 of the filter insert 46.

[0073] As illustrated in FIGS. 12 and 13, the filter member 403 is positioned within the housing lumen 50 of the housing 44. The filter member 403 may extend at least partially along the housing lumen 50. For example, the filter member 403 may be coextensive with the housing lumen 50, or may partially extend with the housing lumen 50. In some embodiments, the filter member 403 (e.g., or at least a portion of the filter member 403, the first portion 405) may extend along an entire length 411 of the housing lumen 50. [0074] The filter member 403 may have any suitable shape, for example, a shape conforming to an interior surface of the housing lumen 50. In some embodiments, the filter member 403 is tubular (e.g., circular with a hollow space extending therethrough). In some embodiments, an outer surface of the filter member 403 is in contact with an inner surface of the housing 44. In other embodiments, the outer surface of the filter member 403 may be spaced a distance apart from the inner surface of the housing 44.

[0075] In some embodiments, the filter member 403 includes or is formed at least partially of a hydrophilic material defining a filter member lumen 413. The hydrophilic material may be any suitable material that tends to absorb and/or retain moisture or liquid from a gaseous volume or stream. The hydrophilic material may include a natural or synthetic medium. In some embodiments, the hydrophilic material may include a porous material, a foam, a fibrous material, a hollow fiber, or a batting configured to absorb moisture and liquid from the exhalation. In some embodiments, the hydrophilic material may include at least one polymeric material. In some embodiments, the hydrophilic material may include absorbing beads or particulates dispersed in an absorbing or non-absorbing matrix.

[0076] In some examples, the hydrophilic material of the filter member 403, and, therefore, the filter member 403 in some cases, is relatively flexible. In other embodiments, the hydrophilic material of the filter member 403, and, therefore, the filter member 403 is relatively rigid. The relatively rigid characteristic of the filter member 403 may help eliminate the need for the housing lumen 50 to include an additional component configured to engage with an inlet tube that directs exhalation from the patient 16 into the capnography filter 12. Thus, in some embodiments, there is no separate tube or the like within the housing lumen 50 that is configured to engage with an inlet tube and, instead, the inlet tube engages directly with the filter member 403.

[0077] The embodiment of the capnography filter 12 illustrated in FIG. 12 includes concentric filter member portions 415 disposed in a parallel configuration. For example, the concentric filter member portions 415 include the first portion 405 (e.g., first fiber) and the second portion 407 (e.g., second fiber) arranged concentrically to form the filter member 403. Although FIG. 12 illustrates two concentric filter members portions 414, it should be appreciated that the capnography filter 12 may include any suitable number of concentric filter members portions (e.g., 3, 4, 5, 6, etc.) The parallel configuration may include two or more filter member portions 415 arranged concentrically, such that a flow of exhalation (e.g., absorption of liquids from the exhalation) through the two or more concentric filter member portions 415 is occurring substantially at a same time, or there is a relatively short travel time for the flow of exhalation between each concentric layer of the two or more filter member portions 415.

[0078] Respective lengths of the concentric filter member portions 415 may vary to achieve a tapering shape. In particular, the first portion 405 may have a smaller diameter (e.g., outer diameter and/or inner diameter) than a diameter (e.g., outer diameter and/or inner diameter) of the second portion 407 surrounding the first portion 405. Further, the first portion 405 may have a longer length than a length of the second portion 407. Each of the concentric filter member portions 415 may include or be formed of a same absorbing material, or in some embodiments, at least one of the concentric filter member portions 415 may include or be formed of a different absorbing material than another concentric filter member portion 414.

[0079] In addition, as illustrated, the filter insert 46 may be concentrically positioned around the first portion 405 of the filter member 403. In particular, an interior surface 424 of the filter insert 46 (e.g., forming the filter insert lumen 78) may face or abut (e.g., partially abut) an outer surface 426 of the first portion 405 of the filter member 403. Furthermore, in some embodiments, the filter insert 46 may not surround the second portion 407 of the filter member 403. As illustrated, a first surface 428 (e.g., end surface) of the filter insert 46 may face (e.g., abut, edge, join) a second surface 430 (e.g., end surface) of the second portion 407 of the filter member 403.

[0080] The embodiment of the capnography filter 12 illustrated in FIG. 13 includes the filter member 403 positioned downstream, with respect to the direction 206 of flow of the moisture and/or liquid from the gap 84 (e.g., and along the one or more channels 200), relative to the filter insert 46. In other words, a first outer surface 416 of the filter member 403 may face (e.g., abut, edgejoin) a second outer surface 418 of the filter insert 46. As such, moisture and/or liquid collected and directed, via the one or more channels 200, with respect to the direction 206 may be collected and/or absorbed (e.g., drawn into) the filter member 403 from the one or more channels 200.

[0081] Continuing with the description of embodiments of FIGS. 12 and 13, the housing 44 may also define the one or more chambers (e.g., lumens) positioned downstream of the gas- permeable hydrophobic barrier 48, with respect to the flow direction 64 of an exhalation sample. In the illustrated embodiments of FIGS. 12 and 13, the one or more chambers may include at least the first outlet chamber 66 fluidly coupled to the housing lumen 50. In particular, a portion of the exhalation sample (e.g., the dry gasses portion) may cross the gas-permeable hydrophobic barrier 48 and enter the first outlet chamber 66. The one or more chambers may include the second outlet chamber 68. The second outlet chamber 68 may be fluidly coupled to the first outlet chamber 66 and configured to receive the portion of the exhalation sample that crossed the gas-permeable hydrophobic barrier 48. In some embodiments, a shape of the second outlet chamber 68 may facilitate pneumatic coupling of the capnography filter 12 to a port of the capnography monitor or module 20.

[0082] Moreover, the housing 44 may define the outlet 72. In particular, the outlet 72 may enable a filtered portion of the exhalation sample to exit the capnography filter 12. The outlet 72 may comprise an outlet of the second outlet chamber 68. As discussed herein, the capnography filter 12 may be coupled to the capnography monitor or module 20. As such, the outlet 72 may enable a portion of the exhalation sample (e.g., the filtered portion, the dry gases portion) to be received by the sensor 22 of the capnography monitor or module 20.

[0083] The housing 44 may include or be formed by any suitable rigid or soft material. For example, the housing 44 may be rigid and resist deformation, or may be flexible or soft and permit deformation. In some embodiments, the housing 44 includes one or more polymeric material. The housing 44 may be transparent or translucent to permit visual inspection of an interior of the housing 44, for example, to ascertain a condition of the capnography filter 12 (e.g., the filter member 403).

[0084] The configuration of the capnography filter 12 that includes the filter member 403, as well as other filtration devices described herein, enables the capnography filters to be relatively easily modified to accommodate different intended times of use. For example, one or more properties associated with the filter member 403 may be adjusted and thus affect a time of use or life of the capnography filter 14. For example, the one or more properties may include a size, a capacity, and a diameter. An increase in size, capacity, diameter, or any combination thereof, may accommodate a longer intended duration of use of the capnography filter 12. On the other hand, a decrease in size, capacity, diameter, or any combination thereof, may accommodate a shorter intended duration of use of the capnography filter 12. A clinician can select from a plurality of different filter members (e.g., that include different properties) based on the intended duration of use with a patient.

[0085] While a single filter insert 46, a single gas-permeable hydrophobic barrier 48, and a single filter member 403 are described with reference to FIGS. 11-13, example capnography filters may include more than one filter member, more than one filter member, and/or more than one gas-permeable hydrophobic barrier. For example, a first gas-permeable hydrophobic barrier may be positioned between two distinct filter inserts and/or two distinct filter members along the housing lumen, and a second gas-permeable hydrophobic barrier may be positioned at or adjacent an end of one of the filter inserts.

[0086] FIG. 14 is a cross-sectional schematic view of the embodiment of the capnography filter 12 of FIG. 13 that includes ten rib projections 420 forming ten rib channels 422 (e.g., the one or more channels 200) therebetween, in accordance to an aspect of the present disclosure. In particular, the cross-sectional view of FIG. 14 is taken through cross-section line D-D illustrated in FIG. 13. As illustrated, the inlet tube 62 is configured to be positioned within the filter insert lumen 78 such that a space (e.g., gap) is formed between the outer surface 204 of the inlet tube 62 and the filter insert 46. In addition, as discussed above, the filter insert 46 includes the one or more rib projections 420 that extend substantially radially towards the housing central axis 38. As illustrated, the filter insert 46 includes ten rib projections 400 forming ten rib channels 402 arranged concentrically surrounding the inlet tube 62 within the filter insert lumen 78.

[0087] FIG. 15 is a flow diagram of an embodiment of a method for filtering moisture and liquid from exhalation via a capnography filter 12, in accordance to an aspect of the present disclosure. The method includes receiving (e.g., introducing via an inlet tube), at block 500, an exhalation sample from a patient into a capnography filter including a filter insert forming one or more channels and a gas-permeable hydrophobic barrier. In particular, the exhalation sample may be introduced into a filter insert lumen of the capnography filter. The method further includes collecting, at block 502, moisture and/or liquid (e.g., a portion of the exhalation sample) from the exhalation sample into the one or more channels of the filter insert to form a dried exhalation sample portion. As discussed herein, the moisture and/or liquid portion of the exhalation sample may flow from a distal end or opening of the inlet tube and into an interior gap formed within the filter insert lumen and between the inlet tube and the gas-permeable hydrophobic barrier. Then, due to the adhesion and/or cohesion properties of the moisture and/or liquids (e.g., water), the moisture and/or liquids collected within the gap may be directed to flow in a flow direction opposite a flow direction of the exhalation sample through or along the inlet tube and introduced into the filter insert lumen. Specifically, the moisture and/or liquids may flow along the one or more channels (e.g., via capillary action) and away from the gas-permeable hydrophobic barrier. In some embodiments, the moisture and/or liquids may then flow toward and be absorbed by the filter member. The method further includes receiving, at block 504, a flow of the dried portion of the exhalation sample across the gas-permeable hydrophobic barrier of the device and through an outlet of the capnography filter.

[0088] The method of FIG. 15 may be performed or carried out with any embodiment of the capnography filter according to the present disclosure.

[0089] The subject matter described in detail above may be defined by one or more clauses, as set forth below.

[0090] A capnography system includes a sampling line that transfers an exhalation sample to a capnography monitor, and a capnography filter to filter the exhalation sample prior to the exhalation sample being received by the capnography monitor. The capnography filter includes a housing formed from a water non-absorbent material. The housing defines a housing lumen extending from a first housing lumen end to a second housing lumen end, and one or more channels within the housing lumen to receive a first portion of the exhalation sample. The capnography filter includes a gas-permeable hydrophobic barrier extending across the second housing lumen end such that a second portion of the exhalation sample flows across the gas- permeable hydrophobic barrier and through an outlet of the capnography filter.

[0091] The capnography system of any preceding clause, wherein the housing is tubular, and wherein the capnography filter comprises a filter insert extending at least partially along the housing lumen, defining the one or more channels, and comprising a filter insert lumen.

[0092] The capnography system of any preceding clause, wherein the capnography filter comprises a filter member extending at least partially along the housing lumen and comprising a water-absorptive material to receive the first portion of the exhalation sample.

[0093] The capnography system of any preceding clause, wherein the filter insert comprises one or more projections extending along a length of the filter insert lumen, and radially into the filter insert lumen and towards a central housing axis of the capnography filter.

[0094] The capnography system of any preceding clause, wherein each projection of the two or more projections is space a distance apart from a respective adjacent projection of the two or more projections and forms a respective channel of the one or more channels between each projection and the respective adjacent projection.

[0095] The capnography system of any preceding clause, wherein the capnography filter receives an inlet tube that introduces the exhalation sample into the housing lumen, and wherein the capnography filter causes positioning of the inlet tube within the housing lumen to form a gap between a distal end of the inlet tube and the gas-permeable hydrophobic barrier.

[0096] The capnography system of any preceding clause, wherein the one or more channels comprises a ring-shaped channel formed within the housing and fluidly coupled to the gap, and wherein the first portion of the exhalation sample comprises a moisture or liquid portion of the exhalation sample and the housing is configured to collect the moisture or liquid portion via the ring-shaped channel.

[0097] The capnography system of any preceding clause, wherein the gas-permeable hydrophobic barrier is positioned at the second housing lumen end.

[0098] The capnography system of any preceding clause, wherein the capnography filter does not include any water-absorptive material.

[0099] A capnography filter including a housing that defines a housing lumen extending therethrough and configured to receive an inlet tube that introduces an exhalation sample from a patient into the housing lumen, and one or more projections extending radially within the housing lumen. The capnography filter includes a gas-permeable hydrophobic barrier extending across the housing lumen and allowing passage of dry gases from the exhalation sample to cross the gas-permeable hydrophobic barrier and exit the capnography filter.

[0100] The capnography filter of any preceding clause, wherein the gas-permeable hydrophobic barrier extends transverse to the housing lumen.

[0101] The capnography filter of any preceding clause, comprising a filter member extending at least partially along the housing lumen and comprising a water-absorptive material to receive a portion of the exhalation sample.

[0102] The capnography filter of any preceding clause, wherein the capnography filter causes positioning of the inlet tube within the housing lumen to form a gap within the housing lumen and between a distal end of the inlet tube and the gas-permeable hydrophobic barrier.

[0103] The capnography filter of any preceding clause, wherein the housing comprises a filter insert portion extending at least partially along the housing lumen, wherein the filter insert comprises a filter insert lumen configured to receive the inlet tube, and wherein the one or more projections extend radially into the filter insert lumen.

[0104] The capnography filter of any preceding clause, wherein at least a portion of an outer surface of the inlet tube is spaced a distance apart from an inner surface of the housing. [0105] The capnography filter of any preceding clause, wherein the one or more projections extend at least partially along a length of the housing lumen, and wherein the one or more projections extend radially towards a central housing axis of the capnography filter.

[0106] The capnography filter of any preceding clause, wherein the one or more projections are positioned circumferentially around the housing lumen and each projection of the one or more projections is spaced a distance apart from a respective adjacent projection of the one or more projections.

[0107] The capnography filter of any preceding clause, wherein the one or more projections define one or more channels extending therebetween, wherein each channel of the one or more channels is formed between two adjacent projections of the one or more projections.

[0108] The capnography filter of any preceding clause, wherein the housing comprises a moisture-impermeable material configured to resist absorption of moisture or liquid from the exhalation sample.

[0109] The capnography filter of any preceding clause, wherein the capnography filter does not include any water-absorptive material.

[0110] It should be understood that various aspects disclosed herein may be combined in different combinations than the combinations specifically presented in the description and accompanying drawings. It should also be understood that, depending on the example, certain acts or events of any of the processes or methods described herein may be performed in a different sequence, may be added, merged, or left out altogether (e.g., all described acts or events may not be necessary to carry out the techniques). In addition, while certain aspects of this disclosure are described as being performed by a single module or unit for purposes of clarity, it should be understood that the techniques of this disclosure may be performed by a combination of units or modules associated with, for example, a medical device. These and other examples are within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:

1. A capnography system (10), comprising : a sampling line (18) that transfers an exhalation sample to a capnography monitor (20); and a capnography filter (12) to filter the exhalation sample prior to the exhalation sample being received by the capnography monitor (20), wherein the capnography filter (12) comprises: a housing (44) formed from a water non-absorbent material and defining, a housing lumen (50) extending from a first housing lumen end (52) to a second housing lumen end (54), and one or more channels (200, 300, 402) within the housing lumen to receive a first portion of the exhalation sample; and a gas-permeable hydrophobic barrier (48) extending across the second housing lumen end (54) such that a second portion of the exhalation sample flows across the gas- permeable hydrophobic barrier (48) and through an outlet (72) of the capnography filter.

2. The capnography system (10) according to claim 1, wherein the housing (44) is tubular, and wherein the capnography filter (12) comprises a filter insert (46) extending at least partially along the housing lumen (50), defining the one or more channels (200, 300, 402), and comprising a filter insert lumen (78).

3. The capnography system (10) according to any of claims 1 or 2, wherein the capnography filter (12) comprises a filter member (403) extending at least partially along the housing lumen (50) and comprising a water-absorptive material to receive the first portion of the exhalation sample.

4. The capnography system (10) according to any of claims 2 or 3, wherein the filter insert (46) comprises two or more projections (400) extend along a length (86) of the filter insert (46), and radially into the filter insert lumen (78) and towards a central housing axis (38) of the capnography filter (12).

5. The capnography system (10) according to claim 4, wherein each projection projection (400) of the two or more projections (400) and forms a respective channel (402) of the one or more channels (402) between each projection (400) and the respective adjacent projection (400).

6. The capnography system (10) according to claim 1, wherein the capnography fdter (12) receives an inlet tube (62) that introduces the exhalation sample into the housing lumen (50), and wherein the capnography filter( 12) causes positioning of the inlet tube (62) within the housing lumen (50) to form a gap (84) between a distal end (88) of the inlet tube (62) and the gas-permeable hydrophobic barrier (48).

7. The capnography system (10) according to claim 6, wherein the one or more channels (200, 300, 402) comprises a ring-shaped channel formed within the housing (44) and fluidly coupled to the gap (84), and wherein the first portion of the exhalation sample comprises a moisture or liquid portion of the exhalation sample and the housing (44) is configured to collect the moisture or liquid portion via the ring-shaped channel.

8. The capnography system (10) according to any of claims 1 to 7, wherein the capnography filter (12) does not include any water-absorptive material.

9. A capnography filter (12), comprising: a housing (44) defining, a housing lumen (50) extending therethrough and configured to receive an inlet tube (62) that introduces an exhalation sample from a patient (16) into the housing lumen (50), and one or more projections (400) extending radially within the housing lumen (50); and a gas-permeable hydrophobic barrier (48) extending across the housing lumen (50) and allowing passage of dry gases from the exhalation sample to cross the gas-permeable hydrophobic barrier (48) and exit the capnography filter (12).

10. The capnography filter (12) according to claim 9, comprising a filter member (403) extending at least partially along the housing lumen (50) and comprising a water- absorptive material to receive a portion of the exhalation sample.

11. The capnography filter (12) according to any of claims 9 or 10, wherein the capnography filter (12) causes positioning of the inlet tube (62) within the housing lumen (50) to form a gap (84) within the housing lumen (50) and between a distal end (88) of the inlet tube (62) and the gas-permeable hydrophobic barrier (48).

12. The capnography filter (12) according to any of claims 9 to 11, wherein the housing (44) comprises a filter insert portion (46) extending at least partially along the housing lumen (50), wherein the filter insert portion (46) comprises a filter insert lumen (78) configured to receive the inlet tube (62), and wherein the one or more projections (400) extend radially into the filter insert lumen (78).

13. The capnography filter (12) according to any of claims 9 to 12, wherein at least a portion of an outer surface (204) of the inlet tube (62) is spaced a distance apart from an inner surface (202) of the housing (44).

14. The capnography filter (12) according to any of claims 9 to 13, wherein the one or more projections (400) extend at least partially along a length (58) of the housing lumen (50), and wherein the one or more projections (400) extend radially towards a central housing axis (38) of the capnography filter (12).

15. The capnography filter (12) according to any of claims 9 to 14, wherein the one or more projections (400) define one or more channels (402) extending therebetween, wherein each channel (402) of the one or more channels (402) is formed between two adjacent projections (400) of the one or more projections (400).