Patent Application
20230173215
None.
The present disclosure relates to a medical airway device including a housing, the housing having at least one breathing circuit port, and the housing including an airway filter arranged to filter air flowing through the at least one breathing circuit port.
Medical filters are used in patient airway management situations, e.g. in breathing circuits that connect a patient to a respirator or anesthesia machine. The filters are used to protect the patient from inhaling inspiratory air containing airborne contaminants that may harm the patient, e.g. airborne particulates or aerosols or pathogens of microbial or viral origin that may be airborne by being adhered to or contained in aerosols of droplets of water/liquids. In addition, the filters may protect the respirator or anesthesia machine from being contaminated with pathogens in the expiratory air from patients suffering from airborne infectious diseases.
Hepa filters in the form of pleated relatively rigid plates of textile or paper-like filter material are used, but they are relatively expensive. Electrostatically charged non-woven filters have proven to be efficient in catching particulates or aerosols and are commonly used in medical filters used in airway management, because they are also less expensive than hepa filters and generally takes up less space than pleated HEPA filters.
Commonly-owned U.S. Pat. No. 10,857,321 B2 discloses a filter device including a distal housing comprising a distal inner port and a distal outer port; a proximal housing comprising a proximal inner port and a proximal outer port. The proximal housing is sealingly affixed to the distal housing to form an inspiratory pathway between the distal inner port and the proximal inner port and to form an expiratory pathway between the distal outer port and the proximal outer port that is fluidly sealed from the inspiratory pathway. The inspiratory pathway is laterally adjacent the expiratory pathway. A first filter is arranged in the inspiratory pathway or in the expiratory pathway to filter gases flowing through the inspiratory pathway or the expiratory pathway.
The diameter of the filters and consequently of the filter housings of filter devices as disclosed above is a balance of having a filter surface as large as possible in order to reduce filter resistance and at the same time to reduce the dead space that is inside the filter housing as much as possible, since the dead space in the filter housing may affect ventilation of the patient negatively. In particular in some breathing circuit configurations, increased dead space in the filter housing may lower the volume of fresh air delivered to the patient in each respiration cycle, because more expiratory air may mix with the fresh air intake before it is inhaled. Therefore, an increase of the filter diameter of existing filter devices is typically unwanted. Consequently, in order to meet stricter requirements in terms of viral filtration efficiency (VFE), a solution may be to increase the thickness of the filter material. However, this may again typically lead to increased resistance which may affect respiration negatively.
U.S. Pat. No. 6,858,057 B2 discloses a filter media comprising a synthetic microfiber polymer fine fiber web wherein the diameter of the fibers is between about 0.8 to about 1.5 microns.
WO 2018/017937 A1 relates generally to filter media and methods for filtering gas streams, and specifically, to filter media having efficiency stability and/or good performance characteristics such as low resistance.
The object of the present disclosure is to provide a medical airway device having increased viral filtration efficiency without increasing dead space and with as little increase of filtration resistance as possible.
In view of this object, the airway filter includes a layered filter including at least a first separate filter layer and a second separate filter layer, the at least first and second separate filter layers are stacked on top of each other so that neighbouring separate filter layers abut each other, the layered filter has a first surface being laminated with a first scrim layer and a second surface being laminated with a second scrim layer, and each separate filter layer is a non-woven fiber layer.
In this way, by stacking at least a first and a second separate filter layer on top of each other, the airway filter surprisingly has a lower filter resistance than a corresponding single layer airway filter having the same total basis weight, i.e. weight per area, and having the same material composition and fiber diameter. For instance, an airway filter having two non-woven fiber layers, each having a basis weight of 150 grams per square meter, has a lower filter resistance than a corresponding airway filter having a single non-woven fiber layer with a basis weight of 300 grams per square meter. The viral filtration efficiency of the layered filter is not significantly affected in relation to that of the comparable single layer filter. Thereby, the viral filtration efficiency may be increased substantially without a substantial increase in filter resistance.
In an embodiment, each separate filter layer is electrostatically-charged. Electrostatically charged fibers may contact and catch more aerosol droplets/particulates than fibers not being electrostatically charged, and thereby, filtration efficiency may be improved. Most particles and aerosols, and especially those of water, have a surface charge. Therefore, the electrostatically charged surface on the fibers in the filter may attract the charged surface on the aerosols/particles and thereby cause improved removal/filter efficiency.
In an embodiment, each separate filter layer is made of blended synthetic fibers.
In an embodiment, each separate filter layer comprises or consists of spun polypropylene fibers.
In an embodiment, each separate filter layer is a needle punched material.
In an embodiment, each separate filter layer is made of the same type of material, i.e. material composed by the same type of fibers and material having the same density.
In an embodiment, the first and second scrim layers are textile membranes of non-woven polypropylene. The textile membranes may be hydrophobic. The scrim layers may mitigate fiber migration from the non-woven fiber layers of the layered filter itself, which may be looser spunbond sheets than the scrim layers.
In an embodiment, the first and second scrim layers are needle punched onto their respective separate filter layers.
In an embodiment, the total basis weight of the layered filter including the separate filter layers, but excluding the scrim layers, is at least 250 grams per square meter.
In an embodiment, the basis weight of each separate filter layer is at least 20 percent of the total basis weight of the layered filter including the separate filter layers, but excluding the scrim layers.
In an embodiment, the medical airway device is a filter device, the housing includes a proximal housing part and a distal housing part, the proximal housing part has a proximal connector forming a first breathing circuit port, the distal housing part has a distal connector forming a second breathing circuit port, the proximal housing part and the distal housing part are sealingly connected to each other, and the airway filter is arranged at the connection between the proximal housing part and the distal housing part.
In an embodiment, a foam sponge is arranged in the proximal housing part to filter air flowing between the single proximal connector and the airway filter.
In an embodiment, the medical airway device is a filter device, the housing includes a proximal housing part and a distal housing part, the proximal housing part has a proximal inspiratory connector and a proximal expiratory connector, each forming respective breathing circuit ports, the distal housing part has a distal inspiratory connector and a distal expiratory connector, each forming respective breathing circuit ports, the proximal housing part and the distal housing part are sealingly connected to each other, the airway filter is arranged at the connection between the proximal housing part and the distal housing part, the airway filter includes an inspiratory airway filter arranged to filter air flowing between the proximal inspiratory connector and the distal inspiratory connector, and the airway filter includes an expiratory airway filter arranged to filter air flowing between the proximal expiratory connector and the distal expiratory connector.
In an embodiment, the inspiratory airway filter and the expiratory airway filter are formed by separate parts of one single layered filter arranged in the housing.
In an embodiment, at least the distal inspiratory connector and the distal expiratory connector are arranged concentrically.
In an embodiment, at least the proximal inspiratory connector and the proximal expiratory connector are arranged non-concentrically, and one of the proximal inspiratory connector and the proximal expiratory connector extends laterally from the proximal housing part.
In an embodiment, the medical airway device is a resuscitator including a self-inflating squeeze bag having a squeeze bag inlet opening forming a first breathing circuit port and a squeeze bag outlet opening forming a second breathing circuit port, the squeeze bag inlet opening accommodates a squeeze bag inlet valve housing including a squeeze bag inlet valve arrangement being adapted to allow inflow of air into the squeeze bag and being adapted to prevent outflow of air from the squeeze bag through the squeeze bag inlet opening, the squeeze bag outlet opening accommodates a patient valve housing including a patient valve arrangement being adapted to allow outflow of air from the squeeze bag into the patient valve housing and being adapted to prevent inflow of air into the squeeze bag through the squeeze bag outlet opening, the patient valve housing further includes a patient connection port for ventilation of a patient and a patient expiration outlet port for outlet of exhaled gas from the patient valve housing to the surroundings, and the airway filter is located upstream the squeeze bag outlet opening in order to filter air before reaching the patient valve arrangement from the squeeze bag.
In an embodiment, the medical airway device is a face mask for ventilation and/or preoxygenation of a patient, the face mask includes a dome and a face contact cuff, the dome is provided with a connector forming the at least one breathing circuit port, and the airway filter is arranged inside the dome.
In an embodiment, the medical airway device is a PEEP valve for the control of flow and/or pressure at an expiratory connector forming the at least one breathing circuit port.
In an embodiment, the PEEP valve includes a PEEP valve housing having a peripheral PEEP valve housing wall, the peripheral PEEP valve housing wall is provided with a number of patient expiration outlet openings for outlet of exhaled gas from the PEEP valve housing to the surroundings, and the airway filter is arranged to filter air flowing through the patient expiration outlet openings.
In an embodiment, the airway filter is generally tubular and at least partly conical and/or partly cylindrical and covers an outside of the peripheral PEEP valve housing wall.
The disclosure will now be explained in more detail below by means of examples of embodiments with reference to the very schematic drawing, in which
In the following, generally, similar elements of different embodiments have been designated by the same reference numerals.
According to the present disclosure, medical filters may be incorporated by means of a medical airway device in different ways both in dual limb breathing circuits 1 and in single limb breathing circuits 13 as described above in order to protect the patient from inhaling inspiratory air containing airborne contaminants that may harm the patient, e.g. airborne particulates or aerosols or pathogens of microbial or viral origin that may be airborne by being adhered to or contained in aerosols of droplets of water/liquids. In addition, the filters may protect the respirator or anaesthesia machine 3 from being contaminated with pathogens in the expiratory air from patients suffering from airborne infectious diseases.
According to the present disclosure, a medical airway device includes an airway filter 32, 53, 54 having increased viral filtration efficiency without increasing dead space and without significantly affecting filtration resistance.
As illustrated in
Each separate filter 75, 76 layer may preferably be electrostatically-charged, is preferably made of blended synthetic fibers, or is preferably made of or comprises spun polypropylene fibers. The filter layers 75, 76 may be non-woven mats of felts which means that they have the fibers in a random orientation (being neither woven or knitted). The fibers in non-woven felts are typically meltblown. Each separate filter layer may be a needle punched material and is preferably made of the same type of material when it comes to fiber material, fiber type, average fiber diameter, average fiber length, and fiber arrangement. The first and second scrim layers 78, 80 are preferably textile membranes of non-woven polypropylene and are preferably needle punched onto their respective separate filter layers. The non-woven scrim is spunbound which includes that the fibers are bonded thermally or by a resin, which gives a stronger textile. The total basis weight of the layered filter 74 including the separate filter layers 75, 76, but excluding the scrim layers 78, 80, is preferably at least 200 grams per square meter, more preferred at least 250 grams per square meter, and more preferred about 300 grams per square meter. The basis weight of each separate filter layer 75, 76 is at least 20 percent, preferably at least 30 percent, more preferred at least 40 percent, and most preferred at least 45 percent of the total basis weight of the layered filter including the separate filter layers 75, 76, but excluding the scrim layers 78, 80.
The at least two separate filter layers 75, 76 may include a filter material based on textiles. The separate filter layers 75, 76 may generally have the form of bacterial and/or viral filters. The layered filter 74 may be able to remove up to 99.99% or 99.9999% of virus or bacteria from air.
The layered filter 74 may include multiple layers of non-woven textiles made from fibres of polyester, polypropylene, acrylics or polystyrene or mixtures thereof. Alternatively, two, three or more layers (e.g. of different arrangements) of the same fibre or fibre mixture may be used. Each layer may be of different fibres and/or different arrangements. The layered filter 74 may include at least two or three layers of non-woven polypropylene fibres or acrylic/polystyrene nonwoven fibres.
The layered filter 74 includes at least two non-woven fiber layers 75, 76 with a scrim layer 78, 80 on each surface. The layered filter 74 may be a flat or shaped filter with a non-woven fiber layer (e.g. of spun polymer fibers, such as a blend of different synthetic polymer fibers, or one type of fibers, such as spun polypropylene (PP) fibers). The fibers may be treated to have an electrostatic charged surface. The density of this non-woven filter layers is e.g. between 100 g/m2 and 400 g/m2 (Grams Per Square Meter). The density of each non-woven filter layer is preferably 150-350, more preferred 150-300 even more preferred 150-250 and most preferred 100-200 g/m2. The layered filter may be provided with scrim layers, such as thin (15 g/m2) layers of hydrophobic textile membrane (of non-woven polymer, e.g. a polypropylene (PP)) on both surfaces of the layered filter.
The electrostatic charge on the surface of the fibers attract aerosols or particles that may carry microbes or virus. Most airborne bacteria and virus use aerosols as a transport media. The aerosols are produced when people exhale, speak, sneeze or cough. The surface charge of the aerosols results in that the aerosols are attracted to the electrostatically charged filter material, thus providing an improved filter efficiency. An example of suitable commercially available electrostatic filters are e.g. TECHNOSTAT® or TECHNOSTAT PLUS™ by Hollingsworth & Vose.
Although not fully understood, the reason may be that because a 300 g/m2 filter is more dense and has smaller voids between the individual fibers in the non-woven layer compared with a 150 g/m2 filter layer, the larger voids between the individual fibers may reduce the filter resistance and also allow the air to follow a labyrinthic or tortuous path through the filter media and thereby increase the chance of the possibly electrostatically charged fibers to contact and catch more aerosol droplets and/or particulates. Further, the intermediate space between the two discrete layers of nonwoven filter material may contribute in distributing air over the filter surface and/or may contribute to lowering the filter resistance.
It may further be concluded that, by stacking at least a first and a second separate filter layer on top of each other, the airway filter surprisingly has a lower filter resistance than a corresponding single layer airway filter having the same total basis weight, i.e. weight per area.
The proximal housing part 25 and the distal housing part 24 are sealingly connected to each other, for instance by being glued or ultrasonically welded along peripheral contact surfaces 30, 31. As seen, the peripheral contact surfaces 30, 31 may form a groove and tongue joint. An airway filter 32 is arranged at the connection between the proximal housing part 25 and the distal housing part 24. As seen, the airway filter 32 is flat and circular, and preferably, the airway filter 32 is pinched between corresponding peripheral faces of the proximal housing part 25 and the distal housing part 24 in order to prevent a leak path around, instead of through, the airway filter 32. Furthermore, the airway filter 32 is pinched between corresponding internal separating walls 47 of the proximal housing part 25 and the distal housing part 24, respectively, in order to prevent a leak path between the inspiratory channel 48 and the expiratory channels 49 of the housing 23. As seen, according to this third embodiment, the flat and circular airway filter 32 forms both an inspiratory airway filter arranged to filter air flowing between the proximal inspiratory connector 43 and the distal inspiratory connector 39 and an expiratory airway filter arranged to filter air flowing between the proximal expiratory connector 44 and the distal expiratory connector 40.
The airway filter 32 can also be arranged at the transit between the squeeze bag 57 and the patient valve housing. The shown positions of the airway filter 32 in or on the resuscitator are merely exemplary and non limiting since it is clear that the airway filter 32 could be placed anywhere upstream of the patient valve, including upstream of the inlet valve housing.
International Patent Application No. PCT/EP2021/077256 disclosing a resuscitator including a self-inflating squeeze bag is hereby incorporated by reference. Some of the filters in the disclosed resuscitator are not flat, but could e.g. be made from a flat sheet of the dual layered filter with a welding seam along the length/height of a cylinder/cone. For instance the filter could have a welding seam along the length of the cylinder that is similar to the welding seam along the outer circumference of the circular flat filter disclosed for filter devices in the present disclosure.
International Patent Application No. PCT/EP2021/077256 mentioned above and incorporated by reference also disclosed various embodiments of PEEP valves. The cylindrical/conical filters in such PEEP valves as well as in the above described resuscitator could in principle also be made from a flat filter that is attached to the filter housing by squeezing the “seam” along the length/height of a cylinder/cone between two housing parts (inner outer housing parts), e.g. if a protecting “grille” is necessary. It would be possible to use the same principle(s) as described in U.S. Pat. No. 10,857,321 B2 which is hereby incorporated by reference. These principle(s) are e.g. described in FIGS. 9-10 of U.S. Pat. No. 10,857,321 B2. US 2021/0069450 A1 describing similar solutions is equally incorporated by reference in this description.
It is also possible to attach flat filters to the valve housing in the resuscitator or PEEP valve described above by using the same principle as described and illustrated in FIGS. 9-10 of U.S. Pat. No. 10,857,321 B2 and in US 2021/0069450 A1, also along the length of the cone/cylinder. All that is needed is to cut the filters in a shape that results in the cylinder (i.e. a rectangular filter pad) or a conical filter when wrapped “around” the inner valve housing.
The cylindrically/conically shaped filters could also be made from flat filters that are “squeezed” along the length as well by adding a separate “squeezing” bar/frame that covers the edges of the filter which can then be glued or welded (ultrasonically) to the valve housing by using the same connection principle as described and illustrated in FIGS. 9-10 of U.S. Pat. No. 10,857,321 B2 and in US 2021/0069450 A1.
As mentioned above,
The test procedure was performed to evaluate the viral filtration efficiency (VFE) of test articles at an increased challenge level. The test article was a single layer or dual layer filter pad with a filter media configuration as specified in column 2 in
This test procedure was modified to provide a VFE test procedure in order to employ a more severe challenge than would be experienced in normal use. All test method acceptance criteria were met. Testing was performed in compliance with US FDA good manufacturing practice (GMP) regulations 21 CFR Parts 210, 211 and 820.
The filter resistance has been measured as the pressure drop at 30 l/min in accordance with ISO 9360-1 (2nd edition, 2009-06-10).
The filtration efficiency percentages were calculated using the following equation:
% VFE=((C−T)/C)×100
For instance, for P-2 VFE 150/150 of the table of
For instance, for P-2 VFE 150/150 of the table of
A method of making a layered filter according to the present disclosure comprises: providing a first nonwoven, providing a second nonwoven, providing a first scrim and providing a second scrim; arranging the first nonwoven onto the second nonwoven, arranging the first scrim onto the first nonwoven, and arranging the second scrim onto the second nonwoven, thereby providing the layered filter with outer surfaces provided by the first and the second scrims. The first and second scrims may be the same or different. The first and second nonwoven may be the same or different. The arranging of the nonwovens and the scrims may be done in any order that results in a stack comprising scrim/nonwoven/nonwoven/scrim. Additional nonwovens may be added in between the first and second nonwoven. Any nonwoven or scrim described above may be used.
The first and second nonwoven may be arranged onto each other first to provide a multi-layer nonwoven, then the first and second scrims may be arranged on outer surfaces of the multi-layer nonwoven.
The first scrim may be arranged onto the first nonwoven to define a first composite layer, the second scrim may be arranged onto the second nonwoven to define a second composite layer, and the first composite layer may be arranged onto the second composite layer with the nonwovens abuting each other. The scrim and the nonwoven may be provided in roll form.
In one variation, the first scrim and the second scrim are the same, the first nonwoven and the second nonwoven are the same, and layered filter is made by arranging a layer of the scrim onto a layer of the nonwoven to define a composite web, folding the composite web in-line along its length, then cutting filter units from the folded composite web. Arranging a layer of the scrim onto a layer of the nonwoven may comprise unwinding rolls of the scrim and nonwoven and placing the scrim over the nonwoven in-line with the unwinding equipment.
The nonwoven and the scrim may be treated or secured to each other in any manner, as described above, including needle-punching and electrostatically charging the nonwoven, the scrim or both, before or after stacking them to provide the composite layers or the folded composite web. The filter units may also be treated.
