Moisture Removal and Condensation and Humidity Management Apparatus for a Breathing Circuit

Abstract

A moisture removal and condensation and humidity management apparatus for a breathing circuit comprises a breathing circuit tubing defining a breathing gas conduit. The breathing gas has a first humidity level and a level of moisture therein. A dry gas conduit is adjacent at least a portion of the breathing gas conduit. The dry gas flow is configured to have a second humidity level lower than the first humidity level. A moisture transmission pathway is provided between the breathing gas conduit and the dry gas conduit, such that humidity in the flow of breathing gas is lowered and moisture is transferred to the dry gas flow. The moisture transmission pathway may be provided by a permeable portion which is permeable to water vapor but impermeable to liquid water, or by one or more perforations which permit drainage of liquid water from the breathing gas conduit to the dry gas conduit.

Claims

1. A moisture removal apparatus comprising: a first tube; a second tube, the first tube and the second tube defining: a breathing gas conduit that directs a flow of breathing gas in a direction from an upstream end of the apparatus to a downstream end of the apparatus; and a dry gas conduit that directs a dry gas flow in the direction from the upstream end of the apparatus to the downstream end of the apparatus; and a moisture transmission pathway between the breathing gas conduit and the dry gas conduit that lowers the humidity of the breathing gas by transferring the humidity to the dry gas flow.

2. The moisture removal apparatus of claim 1, wherein the moisture transmission pathway is permeable to water vapor but impermeable to liquid water.

3. The moisture removal apparatus of claim 1, wherein the first tube is an inner tube and the second tube is an outer tube that is concentric with the inner tube.

4. The moisture removal apparatus of claim 3, wherein the inner tube defines the breathing gas conduit, and further comprising an annular space between the inner tube and the outer tube, the annular space defining the dry gas conduit.

5. The moisture removal apparatus of claim 1, wherein at least one of the first tube or the second tube is a corrugated tube.

6. The moisture removal apparatus of claim 3, wherein the inner tube includes a permeable portion that defines the moisture transmission pathway that is permeable to water vapor but impermeable to liquid water.

7. The moisture removal apparatus of claim 6, wherein the permeable portion spans the entire wall of the inner tube.

8. The moisture removal apparatus of claim 6, wherein the permeable portion includes a hydrophilic polyester ester membrane.

9. The moisture removal apparatus of claim 1, further comprising: an exit port fluidly coupled to the dry gas conduit; and a filter fluidly coupled to the exit port.

10. The moisture removal apparatus of claim 1, wherein the apparatus is configured to be an expiratory limb of a ventilator circuit.

11. The moisture removal apparatus of claim 1, wherein the dry gas conduit is a first dry gas conduit, the dry gas flow is a first dry gas flow, the direction is a first direction, and further comprising: a return conduit that directs a second dry gas flow in a second direction from the downstream end to the upstream end of the apparatus.

12. A moisture removal apparatus comprising: an inner tube defining a breathing gas conduit that directs a flow of breathing gas, the inner tube including a permeable portion that defines a moisture transmission pathway that is permeable to water vapor; an outer tube concentric with the inner tube; an annular space between the inner tube and the outer tube, the annular space defining a first dry gas conduit that directs a first dry gas flow in a first direction from a first end of the apparatus to a second end of the apparatus; and a return conduit that directs a second dry gas flow in a second direction from the second end of the apparatus to the first end of the apparatus.

13. The moisture removal apparatus of claim 12, wherein the return conduit is positioned within the annular space.

14. The moisture removal apparatus of claim 13, further comprising a dividing wall between the inner tube and the outer tube that divides the annular space into the first dry gas conduit and the return conduit.

15. The moisture removal apparatus of claim 12, wherein the outer tube is a corrugated tube; and wherein the moisture transmission pathway is impermeable to liquid water.

16. The moisture removal apparatus of claim 12, wherein the apparatus is configured to be an expiratory limb of a ventilator circuit.

17. A moisture removal apparatus comprising: a breathing circuit tube including: a breathing gas conduit that directs a flow of breathing gas in a first direction from a first end of the apparatus to a second end of the apparatus; and a dry gas conduit that directs a first dry gas flow in the first direction; and a moisture transmission pathway between the breathing gas conduit and the dry gas conduit that lowers the humidity of the breathing gas by transferring the humidity to the first dry gas flow; and wherein the moisture removal apparatus includes at least one of: a return conduit that directs a second dry gas flow in a second direction from the second end of the apparatus to the first end of the apparatus; or a dividing wall that divides the breathing circuit tube into the breathing gas conduit and the dry gas conduit, the dividing wall including a permeable portion that defines the moisture transmission pathway, the moisture transmission pathway being permeable to water vapor.

18. The moisture removal apparatus of claim 17, wherein the breathing circuit tube is a corrugated tube.

19. The moisture removal apparatus of claim 17, wherein the moisture transmission pathway is impermeable to liquid water.

20. The moisture removal apparatus of claim 17, wherein the moisture removal apparatus includes the return conduit that directs the second dry gas flow in the second direction from the second end of the apparatus to the first end of the apparatus; and further comprising: an inner tube that defines the breathing gas conduit; and an outer tube concentric with the inner tube, the inner tube and outer tube defining an annular space between the inner tube and the outer tube, the annular space defining the breathing gas conduit; and wherein the return conduit is positioned within the annular space.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 is a schematic view illustrating an apparatus incorporated into or as part of a breathing gas circuit in accordance with one or more embodiments of the present invention;

[0027] FIG. 2 a schematic cross-sectional view illustrating the apparatus of FIG. 1 in one or more embodiments of the present invention;

[0028] FIG. 3 a schematic cross-sectional view illustrating the apparatus of FIG. 1 in one or more additional embodiments of the present invention;

[0029] FIG. 4 is a schematic cross-sectional view of an apparatus incorporated into or as part of a breathing gas circuit in accordance with one or more additional embodiments of the present invention.

DETAILED DESCRIPTION

[0030] The invention will now be described with reference to the drawing figures, in which like parts are referred to with like reference numerals throughout. One or more embodiments in accordance with the present invention provide a moisture removal and condensation and humidity management apparatus for a breathing circuit to rapidly remove water vapor or condensate from a humidified medical gas traveling through a breathing circuit between a ventilator and a patient or the patient and the ventilator. As used herein, a “breathing circuit” or “breathing gas circuit” is any arrangement of tubing or conduits which carries gases to be administered to and from a patient, such as from a ventilator, and which may include additional accessories or devices attached to it. Such “breathing gases” may include oxygen, air or any component thereof, and are configured for absorbing high levels of moisture and/or being humidified prior to administration to a patient, or during administration to a patient, suitable for medical applications.

[0031] FIG. 1 is a schematic view illustrating an apparatus incorporated into or as part of a breathing gas circuit in accordance with one or more embodiments of the present invention. A moisture removal and condensation and humidity management apparatus 10 for a breathing circuit includes a section or length of breathing circuit tubing 11 defining a breathing gas conduit 12 for a flow (B) of breathing gas therein. The breathing gas flows from a first, upstream end 10A of the device 10, through the conduit 12 defined within device 10, to a second, downstream end 10B of the device 10. The breathing gas is configured to have a first humidity level and a level of moisture therein, which may be calibrated based on the needs of the patient. In one embodiment such a length of breathing circuit tubing 11 may be in an expiratory limb of a breathing circuit, such as, for example, somewhere between a patient and a ventilator. In the device 10, a dry gas conduit 14 is defined adjacent at least a portion of the breathing gas conduit 12 between the first end 10A and second end 10B, for a dry gas flow (D) therein. The dry gas flow (D) is configured to have a second humidity level which is lower than the first humidity level within the breathing gas conduit (B). A dry gas flow is coupled from a dry gas source (not shown) to one or more input ports 40 which feed the dry gas flow (D) into the dry gas conduit 14, which then flows substantially parallel to, or around the breathing gas conduit 12.

[0032] FIG. 2 a schematic cross-sectional view illustrating the apparatus of FIG. 1 in one or more embodiments of the present invention. As shown in FIG. 2, the dry gas conduit 14 may be an annular flow space which is concentric with breathing gas conduit 12. In the embodiment shown in FIG. 2, the breathing circuit tubing 11 may be formed by an inner tube 20 defining the breathing gas conduit 12, and the dry gas conduit 14 is formed by an outer sleeve or tube 22 surrounding the inner tube 20, the dry gas conduit 14 thereby being defined as an annular flow conduit 24 defined between the inner tube 20 and outer tube 22. One, or both, of the inner and outer conduits may be formed by corrugated tubing. Alternatively, the inner tube 20 could define the dry gas conduit 14 and the annular space 24 between the inner and outer tubes 20, 22 could be the breathing gas conduit 12. In the present invention, a sufficient stretch of surface area is shared along the breathing circuit tubing 11 between the breathing gas conduit 12 and dry gas conduit 14 such that a moisture and humidity transmission pathway is enabled between the two conduits, as further described below.

[0033] The present invention provides one or more embodiments which provide a moisture transmission pathway between the breathing gas conduit 12 and the dry gas conduit 14, such that humidity in the flow of breathing gas (B) is lowered and moisture in the flow of breathing gas (B) is transferred to the dry gas flow (D). In FIG. 2, such a moisture transmission pathway (T) occurs between the higher humidity breathing gases in conduit 12 and the lower humidity dry gas flow in conduit 14. A user can increase or decrease the level of dry gas supplied to the circuit to manage or remove the condensate which may be transmitted from the breathing gas (B) to the dry gas conduit. The moisture level thus may be reduced from within the breathing gas flow and transferred to the dry gas flow. In one or more embodiments, such as shown in FIG. 2, the breathing circuit tubing 11 comprises a permeable portion (not shown) along part or all of the inner conduit 20 is provided, which is permeable to water vapor but impermeable to liquid water, such that the moisture transmission pathway (T) is provided by such permeable portion of the breathing circuit tubing. The materials comprising the permeable portion are water vapor breathable and allow passage of water vapor, as is well known to those of ordinary skill in the art. The permeable portion may form some or all of the walls of the breathing gas conduit 12, such as inner tube 20, and may include a single, or composite outer, layer of water vapor breathable medium. In one embodiment, an additional wicking layer may be added to the permeable portion. In the embodiment shown in FIG. 2, the additional wicking layer may be disposed as an inner layer of inner conduit 20, configured to be in contact with breathing gas flow (B) inside said conduit. Such a wicking layer may be made of wicking material which allows for adsorption and/or absorption of both moisture and water in any phase, gas or liquid, using a capillary action, while the outer layer of water vapor breathable medium permits the passage of water vapor only and not liquid water.

[0034] Examples of wicking material in the inner layer are a knit or non-woven cloth or fabric, and can be synthetic and made of polyester, polyester and polypropylene blends, nylon, polyethylene or paper, and can be microfilaments or microfiber material such as Evolon® brand fabric material made by Freudenberg & Co. KG. A particular example of wicking material would be a non-woven material of 70% polypropylene and 30% polyester. Another example of the wicking material can be Evolon® brand fabric material having a weight of 60 or 80 grams per square meter. Examples of the outer layer of water vapor breathable medium are Sympatex® brand water vapor permeable membranes made of polymers made by Sympatex Technologies, including monolithic hydrophilic polyester ester membrane, including, as one example, a 12 micron thick membrane.

[0035] In another embodiment of the present invention, the breathing circuit tubing 11 comprises one or more small openings or perforations (not shown) in inner tube 20 which permit drainage of liquid water from the breathing gas conduit 12 to the dry gas conduit 14, such that another, different, moisture transmission pathway T1 is provided by such one or more perforations between the breathing gas flow (B) and dry gas flow (D), such as shown in FIG. 2.

[0036] FIG. 3 a schematic cross-sectional view illustrating the apparatus of FIG. 1 in one or more additional embodiments of the present invention. In FIG. 3, a dividing wall 30 is formed between the inner tube 20 and outer tube 22 in the annular space between said tubes to divide the dry gas conduit into a first, delivery conduit 32 for flow of dry gas (D1) from a first end of the apparatus 10 to a second end of the apparatus, and a second, return conduit 34 for flow of dry gas (D2) from the second end of the apparatus to the first end of the apparatus 10. In this way, the dry gas flow may be re-used, such as, for example, in a closed loop system. One or more moisture transmission pathways may be defined between breathing gas flow conduit (B) and one or both of dry gas conduits (D1, D2), including a permeable membrane incorporated into inner tube 20 as described herein, or a series of perforations in the inner tube 20, as also described herein. The permeable membrane is permeable to water vapor but impermeable to liquid water and may include one or more layers, including a wicking layer, as described above.

[0037] FIG. 4 is a schematic cross-sectional view of an apparatus 100 incorporated into or as part of a breathing gas circuit in accordance with one or more additional embodiments of the present invention. In FIG. 4, a breathing circuit tubing 101 defines a breathing gas conduit 112 for a flow of breathing gas flow (B) therein, said breathing gas having a first humidity level and a level of moisture therein, and a dry gas conduit 114 is formed adjacent at least a portion of the breathing gas conduit 112 for a dry gas flow (D) therein, said dry gas flow configured to have a second humidity level lower than the first humidity level. In FIG. 4, a moisture transmission pathway (T2) is provided between the breathing gas conduit 112 and the dry gas conduit 114, such that humidity in the flow of breathing gas (B) is lowered and moisture in the flow of breathing gas (B) is transferred to the dry gas flow (D). In FIG. 4, the breathing gas conduit 112 and dry gas conduit 114 share a common dividing wall 130, the common dividing wall 130 having the moisture transmission pathway (T2), which may be provided by a permeable membrane incorporated into part or all of the dividing wall 130, as described herein, or a series of perforations in part or all of the dividing wall 130, as also described herein. The permeable membrane is permeable to water vapor but impermeable to liquid water and may include one or more layers, including a wicking layer, as described above.

[0038] In one or more embodiments of the present invention, the dry gas conduit 14, 32, 34, 114 can be closed to ambient air around the apparatus. The dry gas conduit therefore can be configured to provide a stream of dry gas flow at humidity levels which are significantly lower than the humidity in the breathing gas conduit 12, 112. An exit port for the dry gas conduit may further include a filter, the dry gas exiting via the exit port to the ambient environment surrounding the apparatus. Such an exit port may also be connected to a source of suction. An input port for the dry gas conduit may include a flow or volumetric control element for the dry gas flow.

[0039] The present invention therefore uses the differential between humidity or moisture content between the respective flows in the breathing gas conduit 12, 112, vs. the dry gas conduit 14, 32, 34, 114, which allows for greater extraction or diffusion of moisture and humidity from the breathing gas flow to the dry gas flow, which is further assisted by the convective action of the dry gas flow along the common surface area shared between the breathing gas conduit 12, 112, and the dry gas conduit 14, 32, 34, 114, such as along inner conduit 20, or common dividing wall 130.

[0040] The present invention therefore provides a superior way of removal of moisture or water vapor from a breathing circuit, which is better than water traps or other fluid dissipation or moisture removal devices known in the prior art. The result of the inventive apparatus disclosed is that when the apparatus is coupled with a breathing circuit, rainout or condensation in the breathing tube and collection of water within the breathing circuit is significantly reduced. The present invention therefore allows for removal of the collected condensate on the inner walls of a breathing gas conduit, which is then transported away through an outer sleeve which provides the dry gas conduit. The outer tube of the apparatus can also serve to protect the inner tube from damage or puncture, which can be especially vulnerable to damage or puncture when it incorporates a permeable membrane and/or perforations as described herein. To provide additional strength and puncture protection, an additional outer cover structure can be added to the apparatus. The present invention therefore represents an improvement over the known prior art by providing the benefits of: (a) reducing or eliminating user management of condensate levels within a breathing circuit, and/or (b) reducing the humidity output from an expiratory limb of a breathing circuit to reduce the collection of condensate which may be collected in the ventilator.

[0041] The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.