WO1999003525A1

WO1999003525A1 - Breathing filter

Info

Publication number: WO1999003525A1
Application number: PCT/US1998/013981
Authority: WO
Inventors: Frank Natale; Victor Tsalyuk
Original assignee: Pall Corporation
Priority date: 1997-07-16
Filing date: 1998-07-07
Publication date: 1999-01-28
Also published as: AU8384598A

Abstract

A breathing filter device (100) including a housing (10) that can be sealed without welding to provide the seal is disclosed. Preferably, the device includes a heat and moisture exchange filter element (210) that can be disposed in the housing (10) without compression sealing the element (210) between the sections of the housing.

Description

BREATHING FILTER

This application claims the benefit of U.S. provisional patent application

60/052,716, filed July 16, 1997, which is incorporated by reference in its entirety.

Technical Field

This invention relates to breathing filters, particularly heat and moisture exchange filters for use in respiratory care and anesthesiology systems.

Background of the Invention

In the normal breathing process, inhaled air becomes warmed and humidified as it passes through the nasal, tracheal and bronchial passages. The inspired air is also filtered, since the mucus lining the airways of the nasal cavity, nasopharynx and trachea catches bacteria, viruses, particles, and other types of debris brought in by air during inspiration. However, when a patient is connected to a breathing circuit or respiratory care system including a ventilator, e.g., during general anesthesia or artificial respiration, the upper airway is bypassed. As a result, the air (e.g., gas) reaching the bronchial tubes may be neither saturated with moisture, nor filtered, which may adversely impact the patient. Attempts to overcome these adverse effects have included the use of heat and moisture exchange (HME) filters in the patient's breathing circuit. These filters, which typically include an HME medium sealed between the sections of the filter housing, provide for heating and humidifying inspired air, and condensing water from the expired air, and may also include an additional filter medium to provide for removing microorganisms such as bacteria from the expired and inspired air.

However, breathing filters such as HME filters suffer from a number of drawbacks. For example, a breathing filter may be expensive and/or difficult to manufacture. Illustratively, the heat and moisture exchange medium of an HME filter is typically sealed (e.g., by a compression fit) between the filter housing sections and/or by welding the housing sections together. Welding, particularly welding to provide a seal, can be expensive due to, for example, the time and labor involved. Additionally, compressing the medium may increase the differential pressure across the medium and/or reduce the available area for air to flow through. Moreover, the individual sections of the housing may have to be precisely machined for the desired fit, and the filter medium may have to be carefully aligned in the housing before sealing, which can increase manufacturing costs.

Conventional breathing filters have other drawbacks. For example, since breathing filters are designed for one-time use, the filter housing is discarded. Moreover, since the housing sections are typically welded together to provide a seal, it would be labor intensive to separate the sections in order to prepare them for re-use. The present invention provides for ameliorating at least some of the disadvantages of the prior art breathing filters, particularly HME filters. These and other advantages of the present invention will be apparent from the description as set forth below.

Summary of the Invention In accordance with an embodiment of the present invention, a breathing filter device is provided comprising a housing having a first section including a first port and a second section including a second port, and a filter arrangement including a heat and moisture exchange medium disposed in the housing between the first and the second ports without the heat and moisture exchange medium being sealed (e.g., by compression) between the sections of the housing, wherein at least one of the ports is disposed non-perpendicularly to the transverse axis of the filter arrangement.

Another embodiment of the breathing filter device comprises a housing having a first section including a first port and a second section including a second port, and a filter arrangement disposed in the housing between the first and the second ports, wherein the device provides a weld-free seal between the first and second sections of the housing, preferably wherein at least one of the ports is disposed non-perpendicularly to the transverse axis of the filter arrangement.

Typically, the filter arrangement includes a heat and moisture exchange medium and a bacterial filter medium. In preferred embodiments of the filter device, a weld-free seal is formed between the first and second sections of the housing, without sealing the heat and moisture exchange medium between the housing sections. Preferably, both ports of the filter device are disposed non-perpendicularly to the transverse axis of the filter arrangement. In one embodiment, the filter arrangement is replaceable, and the housing is re-usable.

In accordance with the invention, methods for using the filter device are also provided.

Brief Description of the Drawings

Figure 1 is an embodiment of the present invention, illustrating a top view of a device housing including a sealing arrangement. Figure 2 is a bottom view of the device housing illustrated in Figure 1.

Figure 3 is a cross-sectional view of the device along lines I-I of Figure 1. Figure 3 also illustrates the transverse axis of the filter arrangement.

Figure 4 is a view of a portion of Figure 3 , illustrating the sealing arrangement holding sections of the housing together. Figure 5 is an embodiment of the present invention, illustrating a bottom view of the inner surface of one section of the device housing.

Figure 6 is a cross-sectional view of the section of the housing of Figure 5 along lines II-II, illustrating a conical internal.

Figure 7 is a cross-sectional view of a sealing arrangement, including a male thread.

Figure 8 is a side view of the top (or first) section of the device housing, including a female thread.

Figure 9 is a cross-sectional view of another embodiment of the invention.

Figure 10 is an exploded cross-sectional view of the embodiment illustrated in Figure 9.

Figure 11 is a view of a portion of Figure 9, illustrating the sealing arrangement holding sections of the housing together.

Figures 12A and 12B are exploded cross-sectional views of the sealing arrangement shown in Figure 11. Figure 13 is a bottom view of the inner surface of one section of the device housing according to Figure 9.

Figure 14 is a bottom view of the inner surface of the other section of the device housing according to Figure 9.

Specific Description of the Invention

The present invention addresses a need in the art for a breathing filter, particularly an HME filter, that can be sealed without welding. Additionally, the present invention addresses a need for a breathing filter that provides a re-usable housing, and a low differential pressure across the filter medium, preferably while effectively preventing the passage therethrough of undesirable material, e.g., bacteria. Also, the present invention addresses a need for a breathing filter capable of accommodating a variety of types and/or configurations of HME filter media without significantly compressing the HME media. In accordance with embodiments of the invention, a breathing filter device is provided comprising a housing including a first section having a first port and a second section having a second port, the housing defining a fluid flow path between the first port and the second port; a filter arrangement disposed in the housing between the first port and the second port; and a sealing arrangement coupled to the first and/or the second housing sections and movable between a first position in which the first and second sections contact each other and form a weld-free seal, and a second position in which the first and second sections are not sealed.

Another embodiment of a breathing filter device comprises a housing including a first section having a first port and a second section having a second port, the housing defining a fluid flow path between the first port and the second port; and a filter arrangement including a heat and moisture exchange medium disposed in the housing between the first port and the second port; the housing including a sealing arrangement forming a weld-free seal between the first section and the second section without the heat and moisture exchange medium being compression sealed between the first section and the second section.

A breathing filter device according to another embodiment of the invention comprises a housing including a first section having a first port and a second section having an second port, the housing defining a fluid flow path between the first port and the second port; and a filter arrangement disposed in the housing between the first port and the second port; the housing including a sealing arrangement forming a weld-free seal between the first section and the second section; and wherein at least one of the first port and the second port is disposed non-perpendicularly to the transverse axis of the filter arrangement.

In accordance with another embodiment, a breathing filter device comprises a housing including a first section having a first port and a second section having a second port, the housing defining a fluid flow path between the first port and the second port; and a filter arrangement including a heat and moisture exchange medium disposed in the housing between the first port and the second port without the heat and moisture exchange medium being compression sealed between the first section and the second section; at least one of the first port and the second port being disposed non-perpendicularly to the transverse axis of the filter arrangement.

An embodiment of a heat and moisture exchange breathing filter device comprises a housing including a first port and a second port and defining a fluid flow path between the first port and the second port; and a filter arrangement comprising a substantially planar heat and moisture exchange medium having a first surface and a second surface, the heat and moisture exchange medium disposed in the housing across the fluid flow path between the first port and the second port; at least one of the first port and the second port being disposed non-perpendicularly to the first and second surfaces of the heat and moisture exchange medium.

In another embodiment, a heat and moisture exchange breathing filter device according to the invention comprises a housing including a first section having a first port, and a second section having a second port, the housing defining a fluid flow path between the first port and the second port; and a heat and moisture exchange medium having a first surface and a second surface, the heat and moisture exchange medium disposed in the housing across the fluid flow path between the first port and the second port; at least one of: the first port being disposed non-perpendicularly to the transverse axis of the heat and moisture exchange medium; and the second port being disposed non-perpendicularly to the transverse axis of the heat and moisture exchange medium.

Embodiments of the invention also provide methods for treating air or gas using the breathing filter device. For example, in accordance with one embodiment, a method for treating air comprises passing air through a breathing filter device which comprises a housing including a first section having a first port, and a second section having a second port, the housing defining a fluid flow path between the first port and the second port; and a filter arrangement including a heat and moisture exchange medium disposed in the housing between the first port and the second port.

Another embodiment of a method for treating air or gas comprises passing air through a breathing filter device which comprises a housing including a first section having a first port, and a second section having a second port, the housing defining a fluid flow path between the first port and the second port; and a filter arrangement including a heat and moisture exchange medium disposed in the housing between the first port and the second port without the heat and moisture exchange medium being compression sealed between the first section and the second section; stopping the passage of air through the breathing filter device; replacing the filter arrangement in the housing; and passing air through the breathing filter device comprising the replacement filter arrangement.

Yet another embodiment of a method for treating air or gas comprises passing air through a breathing filter device which comprises a housing including a first section having a first port, and a second section having a second port, the housing defining a fluid flow path between the first port and the second port, and a filter arrangement including a heat and moisture exchange medium disposed in the housing between the first port and the second port, wherein at least one port of the housing is disposed non-perpendicularly to the transverse axis of the filter arrangement; stopping the passage of air through the breathing filter device; replacing the filter arrangement in the housing; and passing air through the breathing filter device comprising the replacement filter arrangement.

Each of the components of the invention will now be described in more detail below, wherein like components have like reference numbers.

In the embodiments illustrated in Figures 3 and 9, breathing filter device 100 comprises a housing 10, including a first section 1 having a first port 2, and a second section 3 having an second port 4, providing a fluid flow path between the first port and the second port. A filter arrangement 200 is disposed in the housing 10 across the fluid flow path between the first port and the second port, and the first port 2 and the second port 4 are disposed non-perpendicularly to the transverse axis of the filter arrangement 200. The illustrated embodiments of device 100 include at least two depressions 5,5' along each of the respective inner surfaces of the walls of the first and second housing sections. The device shown in Figures 3 and 9 also includes a sealing arrangement 110, that can be separately movable (Figure 3) or non-movable (Figure 9). In the embodiment illustrated in Figure 3, the housing 10 includes a sealing arrangement 110 coupled to the first section and/or the second section, e.g., a third section 101 that is moveable between a first position in which first section 1 and second section 3 contact each other and form a seal, and a second position in which the first and second sections are not sealed. Figure 4 provides an enlarged cross-sectional view illustrating the sealing arrangement 110 and showing the interaction of the first, second, and third housing sections.

Figure 7 illustrates a cross-sectional view of one embodiment of the sealing arrangement 110 (comprising a third housing section 101), including a member 102, that is capable of engagement with first housing section 1, shown in Figure 8. Thus, Figure 8 illustrates a side view of one embodiment of the first housing section 1 , wherein the first housing section includes a structure 103, which is capable of engagement with member 102 of third housing section 101, as shown in Figure 7.

In other embodiments, the housing can be sealed without a separately movable sealing arrangement. Illustratively, a plurality of housing sections can include portions of a non-movable sealing arrangement, or a single housing section can include the non-movable sealing arrangement.

For example, in accordance with the embodiment illustrated in Figures 9-14, the device 100 can be sealed without a separately movable sealing arrangement, wherein the housing 10 includes a non-movable sealing arrangement 110, and the first and second sections 1,3 can be sealed together without utilizing an additional separate housing section. A highlighted view of the non-movable sealing arrangement 110 is illustrated in Figures 11-14, wherein first section 1 includes a portion 120, capable of receiving and/or engaging with an element 115 of second section 3. The engagement between portion 120 and element 115 provides for sealing the housing.

The filter arrangement 200 according to Figures 3 and 9 can comprise a heat and moisture exchange filter and/or a bacterial filter. In these illustrated embodiments, the filter arrangement 200 comprises at least one heat and moisture exchange filter element 210 and at least one bacterial filter element 220, wherein the heat and moisture exchange filter element is disposed toward the "inlet" or "machine side" of the device 100, and the bacterial filter element is disposed toward the "outlet" or "patient side" of the device. It should be clear that the references to the "inlet", the "machine side", the "outlet", and the "patient side", are for convenience and reference and do not so limit the invention. For example, since the device allows bi-directional flow therethrough, during inspiration, the first port 2 can be the "inlet" port and the second port 4 can be the "outlet" port. However, during expiration, the second port 4 can be the "inlet" port and the first port 2 can be the "outlet" port.

In accordance with a preferred embodiment of the invention, the filter arrangement 200 is disposed in the housing 10, and the first section 1 and the second section 3 of the housing 10 are sealed together without welding or adhesives to form the seal. Such a seal is sufficient to prevent undesirable material, e.g., air and/or microorganisms, from entering the device between the sections of the housing. In a more preferred embodiment, there is no need to subsequently weld the housing sections 1 and 3 together, e.g., the weld-free seal is complete or integral. Thus, the device 100 can be referred to as "self-sealing. " Of course, in those embodiments wherein it is desirable to further secure the sections of the housing together, e.g. , by spot- welding, the seal itself can remain substantially or completely weld-free. Embodiments of the self-sealing device are suitable for use with any type of breathing filter, e.g. , a heat and moisture exchange filter, a bacterial filter, or a filter that provides for heat and moisture exchange as well as bacterial filtration.

In accordance with the embodiments of Figures 3 and 9, the first section 1 and the second section 3 of the housing 10 can be sealed together without welding or adhesives by utilizing a sealing arrangement 110.

For example, in accordance with an embodiment illustrated by Figure 3, a third section 101 can be movably coupled to the first and second sections to maintain contact between the first and second sections as desired. Illustratively, the sealing arrangement 110 can be moveable between a first position in which the first and second sections contact each other and form a weld-free seal, and a second position in which the first and second sections are not sealed. This is further illustrated in Figure 4, that shows the sealing arrangement 110 in a first position in which the first and second sections contact each other and form a weld-free seal. In the embodiment illustrated in Figures 1 and 2, third section 101 comprises a generally annular structure. Third section 101 is preferably securable to second section 3 (shown in side view in Figure 3), wherein the third section 101 is capable of engagement with first section 1 (as shown in Figures 7 and 8).

Figures 7 and 8 illustrate one embodiment wherein third section 101 is capable of rotatable, frictional, or slidable contact and/or engagement with first section 1, e.g., wherein the third section 101 includes at least one member 102, that is capable of engaging with structure 103 of first section 1. A variety of configurations are suitable as is known in the art, e.g., member 102 can include, for example, at least one tab, pin, tongue, or male thread, and structure 103 can include, for example, at least one keyway, slot, groove, or female thread.

In accordance with this illustrated embodiment, the movement of the sealing arrangement from the first position and the second position can provide a progressively tighter seal by, for example, the use of an angled male and female tab or thread.

In another exemplary embodiment (not shown), the sealing arrangement includes one or more structures, typically securable to the first section, that are engageable (e.g., slidably engageable) with the second section. Sections can be coupled and engaged using, for example but not limited to, a press fit, one or more threads, keyways, clips, pins, grooves and/or engageable tabs in or on the sections. As noted earlier, sections can be welded together if desired, e.g. , via a spot weld to secure one section to another.

In yet another embodiment, the first and/or the second section includes the sealing arrangement, and the first and second sections can form a weld-free seal without utilizing a third housing section and/or without a separately movable structure, e.g., by providing a press fit, and/or including, but not limited to, one or more flanges, pins, tongues, grooves, keyways, engageable tabs and/or threads in or on the first and/or second sections.

For example, Figures 9-14 illustrate an embodiment wherein the first and second sections can be sealed without an additional separate housing section and without a separately movable structure, e.g., by providing a press fit between the first and second sections. As shown in Figure 9, and highlighted in Figures 11, 12 A and 12B, device 100 includes sealing arrangement 110, wherein first section 1 has a portion 120 such as, for example, at least one slot or groove, and second housing section includes an element 115 such as, for example, at least one lip or rib. First housing section 1 engages with second section 3, wherein the portion 120 receives or engages with the element 115. As shown in Figure 11, once element 115 is seated in portion 120, the device is sealed. The portion 120 and the element 115 can have a variety of configurations. For example, in the embodiment illustrated in Figures 13 and 14, they can be generally annular ly or circumferentially arranged in the respective housing section, e.g., around the periphery of depression 5. In accordance with any embodiment according to the invention, the device can include additional components, e.g., to improve the efficiency of the seal between the housing sections and/or to secure the filter arrangement in the device. Typically, the housing includes at least one additional structure such as a boss, rib, or lip. For example, in the embodiments illustrated in Figures 11-14, and highlighted in Figures 11, 12A and 12B, the housing includes ribs 140, 145, and 155. The sealing arrangement shown in Figure 11 includes rib 155 that contacts a portion of the outer surface of a wall of slot 120, and the housing includes ribs 140 and 145 that contact the bacterial element 220.

In accordance with any of these embodiments, the seal between the first and second housing sections can be maintained as desired. For example, in those embodiments including a re-usable housing, the first and second sections can be unsealed and disengaged as appropriate, e.g., to discard the used filter arrangement, before re-using the housing with a replacement filter arrangement.

Typically, in those embodiments including a movable sealing arrangement, e.g., in accordance with Figure 3 , the sealing arrangement is moved to a first position to seal the first and second sections, and moved to a second position to unseal the sections. In an alternative embodiment, e.g., in accordance with Figure 9, the sections can be sealed without a separately movable sealing arrangement. For example, the first and second sections can be press fit together to seal the sections, and the sections can be pulled apart to unseal the sections. Additionally, in some embodiments, the filter arrangement 200, or at least the heat and moisture exchange filter element 210 of the filter arrangement 200, can be disposed in the housing without the arrangement 200 or element 210 being sealed between the first and second housing sections. For example, if desired, the heat and moisture exchange filter element 210 can be disposed in the housing 10 without compression sealing the element between the first and second housing sections. Additionally, heat and moisture exchange element 210 can be disposed in the housing without edge sealing, and/or without an interference fit. Illustratively, with reference to some embodiments according to Figures 3 and 9, heat and moisture exchange filter element 210 is disposed in the housing 10 without compressing element 210 between the first section 1 and the second section 3. Additionally, or alternatively, at least one bacterial filter element 220 is disposed in the housing, e.g., compressed between the first and second sections as illustrated in Figures 3 and 9, and highlighted in Figure 11. In another exemplary embodiment (not shown), the heat and moisture exchange filter element is disposed in the housing as described above, and the bacterial filter element is sealed in the housing (e.g., with an adhesive) without compressing the bacterial filter element between the first and second sections of the housing.

Since compression of the heat and moisture exchange filter element 210 can increase the differential pressure across the filter arrangement 200, minimizing or avoiding compression of the heat and moisture exchange filter element can provide a desired level of heat and moisture exchange efficiency while maintaining a desirable differential pressure during the filtering protocol. In accordance with an embodiment of the invention, the pressure differential across the filter arrangement 200 can be minimized while also minimizing or eliminating the possibility that undesirable material, e.g., air and/or microorganisms such as bacteria, can bypass the filter arrangement 200.

Illustratively, the bacterial element 220 can be disposed in the housing across the fluid flow path, e.g., compressed between the first and second sections of the housing. Since the device (containing the heat and moisture exchange element 210) is sealed as described earlier, undesirable material is prevented from entering the device between the sections of the housing. The bacterial element 220 can also be sealed while sealing the device, and/or the element 220 can be separately sealed across the fluid flow path, thus minimizing or preventing the passage of undesirable material from one port of the device to another.

For some of the embodiments wherein the filter device 100 is re-usable, e.g., some embodiments wherein the heat and moisture exchange element 210 is disposed in the housing 10 without edge sealing, or without an interference fit, and/or without compressing the element 210 between the first and second sections 1 and 3 of the housing, it is especially easy to discard and replace the filter arrangement 200. This ease of replacement is particularly the case wherein the bacterial filter element 220 is also disposed in the housing and sealed, and element 220 is disposed therein without using adhesives to retain and/or seal the bacterial filter element in the housing.

Preferably, the filter device includes at least one port that is disposed non-perpendicularly to the transverse axis of the filter arrangement. In the exemplary embodiments of the device 100 illustrated in Figures 3 and 9, both the first port 2 and the second port 4 are disposed non-perpendicularly to the transverse axis of the filter arrangement 200. Thus, both ports are disposed at an angle in the range of greater than 0° and less than 90° to the transverse axis of the filter arrangement. Preferably, both ports are disposed at an angle in the range of greater than about 15° and less than about 40° to the transverse axis of the filter arrangement.

The ports can be disposed at the same, similar, or different angles with respect to the transverse axis of the filter arrangement. If desired, and as illustrated in Figures 3 and 9, the ports 2 and 4 can be disposed non-perpendicularly to the transverse axis of the filter arrangement 200, while the ports can be disposed substantially linearly with respect to each other.

The use of one or more non-perpendicularly disposed ports allows inspired and/or expired air (as used herein, the term "air" including air and/or gas) to be efficiently directed to the filter arrangement, while allowing the air to be exposed to more of the surface(s) of the filter arrangement. Additionally, particularly for those embodiments wherein both the first port and the second port (i.e., the ports on the "machine side" and the "patient side" of the device 100, respectively, as shown in Figures 3 and 9) are disposed non-perpendicularly to the transverse axis of the filter arrangement, the bi-directional air flow through the filter device can be better balanced, providing filter efficiency while minimizing the pressure drop. In some of the embodiments of the device, wherein the filter arrangement provides for heat and moisture exchange as well as bacterial filtration, a typical pressure drop, at a flow rate of about 60 liters/minute, is about 4.9 cm of water column or less, preferably about 3.3 cm of water column or less. One such embodiment provides, for example, a moisture loss of about 6.5 mg/L water loss or less, and a bacterial titer reduction of about 10⁵ or more.

In one embodiment of the device wherein the filter arrangement provides for heat and moisture exchange as well as bacterial filtration, the pressure drop (at the flow rate referenced above) is about 2.5 cm of water column or less at a flow rate of about 60 liters/minute.

If desired, embodiments of the device housing according to the invention can provide a pressure drop, without a filter arrangement interposed in the housing, of about .25 cm of water column or less, at a flow rate of about 60 liters/minute. In one embodiment, the pressure drop of the housing (at the flow rate referenced above) is about .20 cm of water column or less, or about .13 cm of water column or less.

In more preferred embodiments of the invention, the filter device also includes one or more hollows or depressions along the inner surfaces of the walls of the first and/or the second housing sections, i.e., the walls that face the major surfaces of the filter arrangement. For example, in some embodiments of the embodiment of the filter device 100 illustrated in Figures 3 and 9, first housing section 1 and second housing section 3 each include one or more hollows or depressions, e.g., a depression 5 such as a conical internal along the inner surfaces of the walls of the first and second housing sections that face the major surfaces of the filter arrangement 200. As illustrated in Figures 3 and 9, as shown in more detail in Figure 5 (showing a bottom view), and Figure 6 (showing a cross-sectional view), a depression 5 such as a conical internal can include at least one additional depression or hollow 5 ' such as an impression at the ends of ports 2 and 4 respectively. The hollows or depressions 5 and 5' improve the balance of the gas and/or air flow through the filter arrangement and housing. Without being bound to any particular theory, it is believed that the depressions or hollows minimize velocity when the air enters the device and exits the device, e.g., by increasing the area by the port(s) while minimizing an increase in the volume of the device. Put another way, the depressions or hollows minimize velocity at the restriction or "choke" of the port(s). Using Figure 6 for reference, the use of a plurality of depression configurations, e.g., conical (illustrated at reference 5) and non-conical (illustrated at reference 5') can improve the efficiency of velocity control while providing a desirable device volume and pressure drop.

Preferably, the filter device also includes at least one spacer such as, for example, a rib or pin, on the inner surface(s) of the first and/or second housing sections. Typically, one or more spacers can position the filter arrangement in the housing, e.g., to provide support for the filter arrangement and/or minimize contact between the major surfaces of the filter arrangement and the inner surfaces of the first and second housing sections. In some embodiments, the spacer(s) maintain the efficiency of air flow through the device and/or prevent the collapse of the filter arrangement while minimizing the pressure drop across the filter arrangement. For example, using Figures 3 and 9 for reference, with the spacers shown in more detail in Figures 5 and 14, a plurality of spacers 9 on the inner surface of the second section 3 (e.g., along depression 5) prevent a surface of the bacterial filter element 220 from covering the inner surface of the second section 3 , thus allowing efficient air flow while minimizing an increase in the differential pressure. As shown in Figure 13, a similar arrangement can be utilized along the inner surface of the first section 1 to prevent a surface of the heat and moisture exchange element 210 from covering the inner surface of the first section 1. Typically, the spacers prevent a surface of the heat and moisture exchange medium and/or a surface of the bacterial filter element from contacting the inner surface of the first and/or second section of the housing. Embodiments of the device can include any combination of the features as set forth above. Moreover, embodiments of the device can include additional components or structures as is known in the art. For example, the device can include additional ports, including, but not limited to, an access port such as a CO₂ monitor port.

The housing and the sealing arrangement can be produced from any suitable materials (including, but not limited to plastic materials) as is known in the art. Typically, the produced housing sections (e.g., sections 1, 3, and 101) are sterilizable in accordance with protocols known in art, e.g., autoclaving, irradiation, or cold sterilization. In some embodiments, the sections have different characteristics, depending on their intended use. For example, in order to improve sealing efficiency and/or improve the ease of engagement/disengagement, one section can be more compressible and/or flexible than the other. Illustratively, and using Figure 4 for reference, the second section 3 can be produced from a "softer" material, for example, but not limited to, polyethylene or polypropylene, and the first section 1 can be produced from a "harder" material, for example, but not limited to, polycarbonate. As the first and second sections are pressed together (e.g., by using a sealing arrangement 110 comprising third section 101 to engage the first and second sections), the more compressible section "gives" sufficiently to allow the sections to be easily engaged, while maintaining a sufficient seal. Of course, in another embodiment (e.g., in accordance with Figure 9) the first and second sections can differ in compressibility and/or flexibility and be engaged without utilizing a third housing section. Illustratively, the first and/or second sections can provide, for example, a press fit and/or include one or more structures, such as at least one of flanges, threads, tongues, grooves, engageable tabs, and locking clips.

A variety of synthetic (including polymeric and copolymeric) and non-synthetic filter media are suitable for use in the filter arrangement 200 in the breathing device 100 and are known in the art. The filter arrangement can include media that are non-fibrous, fibrous (woven and/or nonwoven), or a composite thereof. The heat and moisture exchange element and the bacterial element can comprise different, similar, or the same media. Illustrative media comprise, for example, a membrane or a foam (e.g., a urethane plastic foam). Additionally, or alternatively, media can comprise, for example, cellulose, rayon, polyethylene, polyamide, or polyester fibers, and/or glass fibers. Media can include a plurality of components. In some embodiments, the heat and moisture exchange element comprises a nonwoven web, and the web can include superabsorbent, hygroscopic, hydrophilic, or hydrophobic fibers, and mixtures thereof. The fibers and/or the web can have a plurality of characteristics.

In addition to the materials listed above, suitable materials include, for example, polyacrylonitrile, polyoxyalkylene glycol, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polypropylene, polymethylpentene, polychlorotrifluoro-ethylene, polyphenyl sulfide, poly(l,4-cyclohexylene dimethylene terephthalate), PETG (a polyester polymerized with an excess of glycol), nylon 6, nylon 66, nylon 612, nylon 11, and a polyamide-polyether copolymer, such as a polyamide/polyalkene-oxide-diamine copolymer, e.g., a nylon 6 copolymer described as "80% nylon 6 with 20% polyethylene-oxide-diamine. "

The media (i.e., the heat and moisture exchange element and/or the bacterial element) can be treated (including, but not limited to, coated and/or impregnated with chemicals or one or more polymers) if desired, e.g., to improve efficiency. For example, the media can be treated with at least one hygroscopic agent.

Preferably, the heat and moisture exchange medium absorbs moisture, and efficiently releases moisture. In some embodiments, the heat and moisture exchange medium comprises a hygroscopic medium.

In some embodiments, the bacterial filter medium includes an electrostatic medium or element. Typically, the bacterial filter medium (that blocks bacteria) is capable of providing a bacterial titer reduction of at least about 10³, more generally, at least about 10⁴, or more.

Suitable media include, but are not limited to, those produced and/or described in UK Patent Application GB 2 267 661 A, European Patent Applications 0 588 214 A2 and 0 265 163 A2, and International Publication WO 96/03194.

The filter arrangement 200 can have a variety of configurations. For example, it can include one or more planar layers or elements and/or corrugated (e.g., pleated) layers or elements. The arrangement can be in the form or a wrap or coil.

It is preferred that the filter arrangement comprises a passive heat and moisture exchange element rather than an active heat and moisture exchange element, e.g., that actively supplies heat and moisture using an external source such as an electrically heated water bath humidifier. Accordingly, in some embodiments according to the invention, the device does not include an active heat and moisture exchange element.

If desired, the housing and/or the filter arrangement can provide for killing, or preventing the replication of, viruses and/or microorganisms, e.g., bacteria. For example, the housing and/or arrangement can include, or be treated with, at least one antibacterial and/or antiviricidal agent as is known in the art. Suitable agents include, but are not limited to, silver nitrate and iodine.

Air may be treated by passing the air through any of the breathing filter device embodiments described above. For example, air may be treated by passing air to be inspired by a patient through a breathing filter device according to any of the embodiments described above, and the heated and humidified air is inspired by the patient.

Subsequently, air expired by the patient is passed through the breathing filter device and water is condensed on the filter arrangement. In some embodiments, the breathing filter device blocks the passage of bacteria therethrough.

In an exemplary embodiment, air is treated by passing air through a breathing filter device which includes a housing which has a first section having a first port and a second section having a second port, wherein the housing defines a fluid flow path between the first port and the second port; and a filter arrangement which includes a heat and moisture exchange medium disposed in the housing between the first port and the second port. The passage of air through the breathing filter device is stopped, the filter arrangement in the housing is replaced, and air is passed through the breathing filter device which includes a replacement filter arrangement. The filter arrangement can be replaced as part of a protocol involving a single patient, or between one patient and another.

In one embodiment, the air is treated for a first patient, and the passage of air is stopped when the treatment protocol is completed. The housing sections are separated, the filter arrangement is discarded, and the housing sections are sterilized. A replacement (new) filter arrangement is placed in the housing, and the housing is sealed. The sealed housing can be sterilized if desired. The filter device with the replacement filter arrangement is then used to treat the air for a second patient.

If desired, any of the housing sections can be replaced or interchanged when replacing the filter arrangement. For example, used housing sections can be sterilized and stored, and interchanged while replacing the filter arrangement. In a preferred embodiment of a method of the invention, at least one port of the housing of the breathing filter device is disposed non-perpendicularly to the transverse axis of the filter arrangement, and air is passed through at least one port non- perpendicularly to the transverse axis of the filter arrangement. In a more preferred embodiment, the first and second ports of the housing of the breathing filter device are disposed non-perpendicularly to the transverse axis of the filter arrangement, and air is passed through at the first and second ports non-perpendicularly to the transverse axis of the filter arrangement.

All of the references cited herein, including publications, patents, and patent applications, are hereby incorporated in their entireties by reference. While the invention has been described in some detail by way of illustration and example, it should be understood that the invention is susceptible to various modifications and alternative forms, and is not restricted to the specific embodiments set forth. It should be understood that these specific embodiments are not intended to limit the invention but, on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Claims

We claim: - 1. A breathing filter device comprising: a housing including a first section having a first port and a second section having a second port, said housing defining a fluid flow path between the first port and the second port; a filter arrangement disposed in the housing between the first port and the second port; and a sealing arrangement coupled to the first and/or the second housing sections and movable between a first position in which the first and second sections contact each other and form a weld-free seal, and a second position in which the first and second sections are not sealed.

2. The device of claim 1, wherein at least one of said first port and said second port is disposed non-perpendicularly to the transverse axis of the filter arrangement.

3. A breathing filter device comprising: a housing including a first section having a first port and a second section having a second port, said housing defining a fluid flow path between the first port and the second port; and a filter arrangement including a heat and moisture exchange medium disposed in the housing between the first port and the second port; said housing including a sealing arrangement forming a weld-free seal between the first section and the second section without the heat and moisture exchange medium being compression sealed between the first section and the second section.

4. A breathing filter device comprising: a housing including a first section having a first port and a second section having a second port, said housing defining a fluid flow path between the first port and the second port; and a filter arrangement disposed in the housing between the first port and the second port; said housing including a sealing arrangement forming a weld-free seal between the first section and the second section; and wherein at least one of said first port and said second port is disposed non- perpendicularly to the transverse axis of the filter arrangement.

5. A breathing filter device comprising: a housing including a first section having a first port and a second section having a second port, said housing defining a fluid flow path between the first port and the second port; and a filter arrangement including a heat and moisture exchange medium disposed in the housing between the first port and the second port without the heat and moisture exchange medium being compression sealed between the first section and the second section; at least one of said first port and said second port being disposed non- perpendicularly to the transverse axis of the filter arrangement.

6. A heat and moisture exchange breathing filter device comprising: a housing including a first port and a second port and defining a fluid flow path between the first port and the second port; and a filter arrangement comprising a substantially planar heat and moisture exchange medium having a first surface and a second surface, said heat and moisture exchange medium disposed in the housing across the fluid flow path between the first port and the second port; at least one of said first port and said second port being disposed non- perpendicularly to the first and second surfaces of the heat and moisture exchange medium.

7. A heat and moisture exchange breathing filter device comprising: a housing including a first section having a first port, and a second section having a second port, said housing defining a fluid flow path between the first port and the second port; and a heat and moisture exchange medium having a first surface and a second surface, said heat and moisture exchange medium disposed in the housing across the fluid flow path between the first port and the second port; at least one of: said first port being disposed non-perpendicularly to the transverse axis of the heat and moisture exchange medium; and said second port being disposed non-perpendicularly to the transverse axis of the heat and moisture exchange medium.

8. The device of any one of claims 1-7, comprising a self-sealing housing.

9. The device of any one of claims 1-8, comprising a re -usable housing.

10. The device of any one of claims 1-9, wherein the filter arrangement is replaceable.

11. The device of any one of claims 1-8, comprising a re-usable device, wherein the filter arrangement is replaceable, and the housing is capable of being sterilized and re-used with a replacement filter arrangement.

12. The device of any one of claims 1-11, wherein the filter arrangement further comprises a bacterial filter having a first surface and a second surface, said bacterial filter disposed in the housing across the fluid flow path between the first port and the second port.

13. The device of any one of claims 1-5 or 7, wherein at least one of the first section and the second section includes at least one conical internal.

14. The device of any one of claims 1-6, wherein the first port is disposed at an angle in the range of greater than 0° and less than 90° to the transverse axis of the filter arrangement, and the second port is disposed at an angle in the range of greater than 0° and less than 90° to the transverse axis of the filter arrangement.

15. The device of claim 14 wherein the first port is disposed at an angle in the range of greater than about 15° and less than about 40° to the transverse axis of the filter arrangement, and the second port is disposed at an angle in the range of greater than about 15° and less than about 40° to the transverse axis of the filter arrangement.

16. The device of any one of claims 1-5 or 7, wherein the first section includes a portion that is compressible by the second section.

17. The device of any one of claims 3, 5, or 7, wherein the heat and moisture exchange medium comprises a pleated medium.

18. The device of any one of claims 3, 5, or 7, wherein the heat and moisture exchange medium comprises a substantially planar medium.

19. The device of claim 12, wherein the bacterial filter is capable of providing a bacterial titer reduction of at least about 10⁴.

20. The device of any one of claims 1-4 wherein the housing includes a third section, the third section including the sealing arrangement.

21. The device of claim 3 or 4, wherein the sealing arrangement provides a press fit seal between the first and second housing sections.

22. A method for treating air comprising: passing the air through the breathing filter device according to any one of claims 1- 21.

23. A method for filtering breathable air comprising: passing breathable air to be inspired by a patient through the breathing filter device according to any one of claims 1-21, and allowing the air to be inspired by the patient; passing air expired by the patient through the breathing filter device.

24. The method of claim 23, wherein the breathing filter device blocks the passage of bacteria therethrough.

25. A method for treating air comprising: passing air through a breathing filter device comprising: a housing including a first section having a first port and a second section having a second port, said housing defining a fluid flow path between the first port and the second port; and a filter arrangement including a heat and moisture exchange medium disposed in the housing between the first port and the second port without the heat and moisture exchange medium being compression sealed between the first section and the second section; stopping the passage of air through the breathing filter device; replacing the filter arrangement in the housing; and passing air through the breathing filter device comprising the replacement filter arrangement.

26. A method for treating air comprising: passing air through a breathing filter device comprising: a housing including a first section having a first port and a second section having a second port, said housing defining a fluid flow path between the first port and the second port; and a filter arrangement including a heat and moisture exchange medium disposed in the housing between the first port and the second port, wherein at least one port of the housing is disposed non-perpendicularly to the transverse axis of the filter arrangement; stopping the passage of air through the breathing filter device; replacing the filter arrangement in the housing; and passing air through the breathing filter device comprising the replacement filter arrangement.

27. The method of claim 26 wherein the first and second ports of the housing are disposed non-perpendicularly to the transverse axis of the filter arrangement, and wherein passing the air through the breathing filter device includes passing air through at the first and second ports non-perpendicularly to the transverse axis of the filter arrangement.