The present invention relates to inhalation airflow regulation devices, and methods of making and using inhalation airflow regulation devices.
Asthma is a disease that constricts the bronchial airways and limits a person's ability to breathe. This condition is a constant problem for many asthma sufferers, frequently causing them to inhale more rapidly than a person who does not have the disease. However, during an asthma attack, a person will begin gasping for breath, so his or her breathing pattern becomes very rapid.
Air is sharply accelerated when entering the mouth and passing through the trachea on its way to the lungs. In order to calm this attack, an asthma inhaler that contains corticosteroids and/or bronchodilators that reduce the inflammation in the airways is used so that normal breathing may resume. The problem is that much of this medication (about 85-95%) is deposited in the mouth, throat, and trachea, especially in the oropharyngeal region, instead of the lungs.
Efforts continue to develop inhalers and inhaler components that do not have some of the problems associated with known inhalers. In particular, efforts continue to develop inhalers and inhaler components that reduce the amount of mouth/throat particle deposition (MTPD), and consequently, the amount of wasted drug.
The present invention continues the effort to develop inhalers and inhaler components by the discovery of inhalation airflow regulation devices that provide controlled air flow through an inhaler so as to increase the amount of medication reaching the user's lungs as oppose to being deposited in the user's mouth, the oropharyngeal region, and trachea region.
In one exemplary embodiment, the inhalation airflow regulation device of the present invention comprises a tubular member having a first end, an opposite second end, and an air flow cross-sectional area between the first end and the opposite second end; an air outlet positioned proximate the first end; a first air inlet positioned proximate the second end; and an air flow regulating member positioned along the tubular member, the air flow regulating member comprising one or more coplanar sheets of material (i) positioned substantially perpendicular to two-way air flow thru the tubular member at a first location within the tubular member, (ii) secured to the tubular member so as to block a portion, but not all, of the air flow cross-sectional area so as to allow two-way air flow thru the tubular member at the first location, and (iii) secured to the tubular member so as to move toward the first end within the tubular member in response to a threshold amount of an inhalation force applied thereon.
In another exemplary embodiment, the inhalation airflow regulation device of the present invention comprises a tubular member having a first end and an opposite second end; a mouthpiece positioned proximate the first end; a first air inlet positioned proximate the second end; a medication inlet positioned along the tubular member between the mouthpiece and the first air inlet; and an air flow regulating member positioned along the tubular member between the medication inlet and the first air inlet, the air flow regulating member regulating air flow that passes thru the tubular member and by the medication inlet.
In yet another exemplary embodiment, the inhalation airflow regulation device of the present invention comprises a tubular member having a first end and an opposite second end; a mouthpiece positioned proximate the first end; a first air inlet positioned proximate the second end; a medication inlet positioned along the tubular member between the mouthpiece and the first air inlet; and an air flow regulating member positioned along the tubular member between the medication inlet and the first air inlet, the air flow regulating member comprising a sheet of material (i) positioned substantially perpendicular to a direction of air flow thru the tubular member, (ii) secured to the tubular member so as to block at least a portion of an air flow cross-sectional area of the tubular member, and (iii) secured to the tubular member so as to move within the tubular member in response to a threshold amount of an inhalation force applied thereon.
In yet another exemplary embodiment, the inhalation airflow regulation device of the present invention comprises a tubular member having a first end, an opposite second end, and an air flow cross-sectional area between the first end and the opposite second end; a mouthpiece positioned proximate the first end; a first air inlet positioned proximate the second end; a medication inlet positioned along the tubular member; and an air flow regulating member positioned along the tubular member, the air flow regulating member comprising a sheet of material (i) positioned substantially perpendicular to two-way air flow thru the tubular member at a first location within the tubular member, (ii) secured to the tubular member so as to block a portion, but not all, of the air flow cross-sectional area to as to allow two-way air flow thru the tubular member at the first location, and (iii) secured to the tubular member so as to move within the tubular member in response to a threshold amount of an inhalation force applied thereon.
Any of the disclosed inhalation airflow regulation devices may be used in combination with a medication canister and/or other components to form an inhaler. In one exemplary embodiment, the disclosed inhalation airflow regulation device is used in combination with at least one medication canister to form an inhaler. In some cases, multiple medication canisters and at least one disclosed inhalation airflow regulation device may be combined to form an inhaler kit. In another exemplary embodiment, the disclosed inhalation airflow regulation device is used in combination with at least one medication canister and a medication canister holding device to form an inhaler kit. In some cases, multiple medication canisters, at least one medication canister holding device, and at least one disclosed inhalation airflow regulation device may be combined to form a kit.
The present invention is also directed to methods of making inhalation airflow regulation devices. In one exemplary embodiment, the method of making an inhalation airflow regulation device comprises forming a tubular member having a first end, an opposite second end, and an air flow cross-sectional area between the first end and the opposite second end, an air outlet positioned proximate the first end, and a first air inlet positioned proximate the second end; and positioning an air flow regulating member along the tubular member, the air flow regulating member comprising one or more coplanar sheets of material (i) positioned substantially perpendicular to two-way air flow thru the tubular member at a first location within the tubular member, (ii) secured to the tubular member so as to block a portion, but not all, of the air flow cross-sectional area so as to allow two-way air flow thru the tubular member at the first location, and (iii) secured to the tubular member so as to move toward the first end within the tubular member in response to a threshold amount of an inhalation force applied thereon.
In another exemplary embodiment, the method of making an inhalation airflow regulation device comprises forming a tubular member having a first end and an opposite second end, a mouthpiece positioned proximate the first end, a first air inlet positioned proximate the second end, and a medication inlet positioned along the tubular member between the mouthpiece and the first air inlet; and positioning an air flow regulating member along the tubular member between the medication inlet and the first air inlet, the air flow regulating member regulating air flow that passes thru the tubular member and by the medication inlet.
In yet another exemplary embodiment, the method of making an inhalation airflow regulation device comprises forming a tubular member having a first end and an opposite second end, a mouthpiece positioned proximate the first end, a first air inlet positioned proximate the second end, and a medication inlet positioned along the tubular member between the mouthpiece and the first air inlet; and positioning an air flow regulating member along the tubular member between the medication inlet and the first air inlet, the air flow regulating member comprising a sheet of material (i) positioned substantially perpendicular to a direction of air flow thru the tubular member, (ii) secured to the tubular member so as to block at least a portion of an air flow cross-sectional area of the tubular member, and (iii) secured to the tubular member so as to move within the tubular member in response to a threshold amount of an inhalation force applied thereon.
In yet another exemplary embodiment, the method of making an inhalation airflow regulation device comprises forming a tubular member having a first end, an opposite second end, an air flow cross-sectional area between the first end and the opposite second end, a mouthpiece positioned proximate the first end, a first air inlet positioned proximate the second end, and a medication inlet positioned along the tubular member; and positioning an air flow regulating member along the tubular member, the air flow regulating member comprising a sheet of material (i) positioned substantially perpendicular to two-way air flow thru the tubular member at a first location within the tubular member, (ii) secured to the tubular member so as to block a portion, but not all, of the air flow cross-sectional area to as to allow two-way air flow thru the tubular member at the first location, and (iii) secured to the tubular member so as to move within the tubular member in response to a threshold amount of an inhalation force applied thereon.
The exemplary methods of making an inhalation airflow regulation device may further comprise one or more additional steps. Suitable additional steps include, but are not limited to, cutting one or more air flow regulating members from a sheet of material wherein each air flow regulating member has a desired shape/configuration; attaching the air flow regulating member to an inner surface of the tubular member; attaching the air flow regulating member to an edge surface of the tubular member;
The present invention is further directed to methods of using inhalation airflow regulation devices. In one exemplary embodiment, the method of using an inhalation airflow regulation device comprises optionally combining the inhalation airflow regulation device with one or more inhaler components; and applying a threshold amount of an inhalation force onto an air flow regulating member positioned along a tubular member of the inhalation airflow regulation device so as to regulate air flow through the inhalation airflow regulation device.
In another exemplary embodiment, the method of using an inhalation airflow regulation device comprises optionally combining the inhalation airflow regulation device with one or more inhaler components; and applying a threshold amount of an inhalation force onto an air flow regulating member positioned along a tubular member between a medication inlet and a first air inlet of the inhalation airflow regulation device, the air flow regulating member regulating air flow that passes thru the tubular member and by the medication inlet with minimal (if any) loss of injected inhalation medication due to early deposition on the user's mouth, the oropharyngeal region, and trachea region.
In another exemplary embodiment, the method of using an inhalation airflow regulation device comprises positioning the inhalation airflow regulation device proximate a user's mouth, the inhalation airflow regulation device comprising a tubular member having a first end and an opposite second end, a mouthpiece positioned proximate the first end, a first air inlet positioned proximate the second end, a medication inlet positioned along the tubular member between the mouthpiece and the first air inlet, and an air flow regulating member along the tubular member between the medication inlet and the first air inlet, the air flow regulating member comprising a sheet of material (i) positioned substantially perpendicular to a direction of air flow thru the tubular member, (ii) secured to the tubular member so as to block at least a portion of an air flow cross-sectional area of the tubular member, and (iii) secured to the tubular member so as to move within the tubular member in response to a threshold amount of an inhalation force applied thereon; and inhaling so as to apply the threshold amount of inhalation force onto the air flow regulating member.
In yet another exemplary embodiment, the method of using an inhalation airflow regulation device comprises positioning the inhalation airflow regulation device proximate a user's mouth, the inhalation airflow regulation device comprising a tubular member having a first end, an opposite second end, an air flow cross-sectional area between the first end and the opposite second end, a mouthpiece positioned proximate the first end, a first air inlet positioned proximate the second end, a medication inlet positioned along the tubular member, and an air flow regulating member along the tubular member, the air flow regulating member comprising a sheet of material (i) positioned substantially perpendicular to two-way air flow thru the tubular member at a first location within the tubular member, (ii) secured to the tubular member so as to block a portion, but not all, of the air flow cross-sectional area to as to allow two-way air flow thru the tubular member at the first location, and (iii) secured to the tubular member so as to move within the tubular member in response to a threshold amount of an inhalation force applied thereon; and inhaling so as to apply the threshold amount of inhalation force onto the air flow regulating member. Desirably, the threshold amount of inhalation force and the air flow regulating member provide an amount of air flow through the tubular device so as to maximize an amount of medication within the air flow that reaches a user's lungs.
These and other features and advantages of the present invention will become apparent after a review of the following detailed description of the disclosed embodiments and the appended claims.
The present invention is further described with reference to the appended figures, wherein:
To promote an understanding of the principles of the present invention, descriptions of specific embodiments of the invention follow and specific language is used to describe the specific embodiments. It will nevertheless be understood that no limitation of the scope of the invention is intended by the use of specific language. Alterations, further modifications, and such further applications of the principles of the present invention discussed are contemplated as would normally occur to one ordinarily skilled in the art to which the invention pertains.
The present invention is directed to inhalation airflow regulation devices and their use with inhalers.
Exemplary tubular member 10 further comprises a first air inlet 18 positioned proximate second end 13. As discussed further below, as a user inhales air or medicated air through tubular member 10, air is pulled into first air inlet 18 and through tubular member 10 toward and through mouthpiece 14. Exemplary tubular member 10 also comprises a region 16 positioned proximate second end 13, and a middle region 19 positioned at an approximate midpoint between first end 11 and opposite second end 13. Exemplary inhalation airflow regulation device 100 may be used in combination with a medicine canister 12 positioned along and connected to tubular member 10 having a first end 11. Typically, medicine canister 12 comprises a pressurized aerosol canister containing a medication. In some embodiments, for example, when exemplary inhalation airflow regulation device 100 is disposable, medicine canister 12 may be permanently attached to tubular member 10. In other embodiments, for example, when exemplary inhalation airflow regulation device 100 is reusable, medicine canister 12 is temporarily attached to and removable from tubular member 10 via a coupling component (see
Medication inlet 22 enables fluid flow from medicine canister 12 into tubular member 10 thru medication inlet 22. As discussed above and as shown in
As shown in
Typically, exemplary air flow regulating member 24 comprises a sheet of elastic material (i) positioned substantially perpendicular to a direction of air flow, as shown by arrow B in
Although exemplary air flow regulating member 24 may comprise any sheet of material, exemplary air flow regulating member 24 typically comprises a sheet of elastomeric material (e.g., neoprene rubber, silicone rubber, etc.). Other suitable materials for forming exemplary air flow regulating member 24 include, but are not limited to a metallic sheet of material, a film, a fiber reinforced film or metal, a fabric, or any combination thereof.
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In this exemplary embodiment, attached edges 26A and 26B, in combination, extend a length representing about 10% of an overall inner perimeter of tubular member 10 as measured along inner surface 32 of tubular member 10, and unattached edges 25A and 25B, in combination, extend a length representing about 90% of an overall inner perimeter of tubular member 10 as measured along inner surface 32 of tubular member 10.
In this exemplary embodiment, exemplary air flow regulating member 24 (i.e., sheets of material 24A and 24B) blocks a portion, but not all, of an air flow cross-sectional area of tubular member 10, wherein the blocked portion is bound by (1)(i) a line extending along inner surface 32 of tubular member 10 from location 36 to location 46, and (ii) a line extending along unattached edge 25A of exemplary air flow regulating member 24 back to location 36, and (2)(i) a line extending along inner surface 32 of tubular member 10 from location 38 to location 48, and (ii) a line extending along unattached edge 25B of exemplary air flow regulating member 24 back to location 38.
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Exemplary overlapping tubular member 50 may comprise any component that enables joining of tubular member portion 10A to tubular member portion 10B. Suitable components for forming exemplary overlapping tubular member 50 include, but are not limited to, a tubular member (e.g., a piece of tubing or pipe material), a heat-shrinkable film, a film, an elastic band, a metal band, etc.
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The air flow regulating member 24 (i.e., comprising one or more sheets of material, e.g., sheet 24 or sheets 24A and 24B) typically blocks up to about 99% of the air flow cross-sectional area at the first location. In some exemplary embodiments, air flow regulating member 24 (i.e., comprising one or more sheets of material, e.g., sheet 24 or sheets 24A and 24B) blocks from about 50% (or about 60%, or about 70%, or about 75%, or about 80%, or about 90%) to about 95% of the air flow cross-sectional area at the first location.
It should be understood that exemplary inhalation airflow regulation device 300 may comprise any desired design for air outlet 180 and connecting member 210 as long as exemplary inhalation airflow regulation device 300 is attachable to a separate inhaler component (not shown). For example, air outlet 180 may actually comprise one or more openings within exemplary inhalation airflow regulation device 300 that configurationally match one or more air inlets of the separate inhaler component (not shown). Further, although connecting member 210 is shown as a strap 212 with hook/loop material 211 thereon, connecting member 210 may have any configuration that enables exemplary inhalation airflow regulation device 300 to be attached to the separate inhaler component (not shown) (e.g., mechanical fasteners such as overlapping end components, adhesive tape, an elastic band, a metal band, etc.
As shown in
As discussed above, exemplary inhalation airflow regulation devices of the present invention may comprise an integral mouthpiece 14 or a separate mouthpiece 14′ that is attachable to tubular member 10 at first end 11.
Typically, inlet tube 80 comprises a relatively hard plastic material 185, such as an ABS (acrylonitrile-butadiene-styrene) copolymer, while mouthpiece cover 110 comprises a relatively soft material 111 such as a silicone rubber material.
Any of the above-described exemplary inhalation airflow regulation devices may further comprise a medication canister connector operatively adapted and sized to receive and utilize a medicine canister.
As shown in
The present invention is also directed to methods of making inhalation airflow regulation devices. In one exemplary embodiment, the method of making an inhalation airflow regulation device comprises forming a tubular member (e.g., tubular member 10) having a first end (i.e., first end 11) and an opposite second end (i.e., second end 13), a mouthpiece (i.e., mouthpiece 14) positioned proximate the first end, a first air inlet (i.e., first air inlet 18) positioned proximate the second end, and a medication inlet (i.e., medication inlet 22) positioned along the tubular member between the mouthpiece and the first air inlet; and positioning an air flow regulating member (i.e., exemplary air flow regulating member 24) along the tubular member, the air flow regulating member regulating air flow that passes thru the tubular member. Typically, the air flow regulating member (i.e., exemplary air flow regulating member 24) is positioned between the medication inlet and the first air inlet, but can be present at any location along the tubular member.
The step of forming a tubular member (e.g., tubular member 10) may comprise a single molding step or multiple molding steps (e.g., to form tubular member portion 10A and tubular member portion 10B, as well as overlapping member 50). The step of positioning an air flow regulating member (i.e., exemplary air flow regulating member 24) along the tubular member may comprise attaching the air flow regulating member to an inner surface of the tubular member (i.e., inner surface 32) or sandwiching the air flow regulating member between outer edges of two portions of a given tubular member (e.g., between outer edges of two portions of tubular member portion 10A and tubular member portion 10B).
The methods of making an inhalation airflow regulation device may further comprise one or more additional steps. Suitable additional steps include, but are not limited to, utilizing or developing a mathematical/computational model in an attempt to better understand fluid flow thru an inhalation airflow regulation device and into a user's lungs; utilizing the mathematical model to design an inhalation airflow regulation device and an air flow regulating member so as to maximize an amount of medicine within an air flow stream reaching a user's lungs from an inhalation airflow regulation device; cutting one or more air flow regulating member portions from a sheet of material; assembling tubular member components and one or more air flow regulating member components; molding a separate mouthpiece component; attaching the mouthpiece component to the first end of the tubular member; attaching a medicine canister (e.g., medicine canister 12) to the tubular member; forming a kit comprising one or more inhalation airflow regulation device components and one or more attachable medicine canisters; and packaging any of the above-mentioned components.
In another exemplary method of making an inhalation airflow regulation device, the exemplary method comprises forming a tubular member (e.g., tubular member 10) having a first end (e.g., first end 11) and an opposite second end (e.g., second end 13), a mouthpiece (e.g., mouthpiece 14) positioned proximate the first end, a first air inlet (e.g., first air inlet 18) positioned proximate the second end, and a medication inlet (e.g., medication inlet 22) positioned along the tubular member between the mouthpiece and the first air inlet; and positioning an air flow regulating member (i.e., exemplary air flow regulating member 24) along the tubular member, the air flow regulating member comprising one or more sheets of material (e.g., single sheet 27 or sheets of material 24A and 24B) (i) positioned substantially perpendicular to a direction of air flow thru the tubular member, (ii) secured to the tubular member so as to block at least a portion of an air flow cross-sectional area of the tubular member, and (iii) secured to the tubular member so as to move within the tubular member in response to a threshold amount of an inhalation force applied thereon. As discussed above, typically, the air flow regulating member (i.e., exemplary air flow regulating member 24) is positioned between the medication inlet and the first air inlet. Further, the air flow regulating member (i.e., exemplary air flow regulating member 24) is typically secured to the tubular member so as to block a portion, but not all, of the air flow cross-sectional area to as to allow two-way air flow thru the tubular member at a first location (e.g., first location 39).
The present invention is even further directed to methods of using inhalation airflow regulation devices described herein.
The inhalation airflow regulation devices and inhalers formed therefrom provide improved, controlled air flow when used in combination, for example, with a pressurized metered dose inhaler (PMDI) with the intent of limiting the speed of the inhalation air flow through a given device to increase the medicine particle deposition in the patient's lungs. The present invention is described above and further illustrated below by way of examples, which are not to be construed in any way as imposing limitations upon the scope of the invention. On the contrary, it is to be clearly understood that resort may be had to various other embodiments, modifications, and equivalents thereof which, after reading the description herein, may suggest themselves to those skilled in the art without departing from the spirit of the present invention and/or the scope of the appended claims.
Studies were performed to predict the behavior of air flow in response to two different flow controller designs. ANSYS CFX was used to create a model of each design and perform tests on the flow controllers computationally. The software was able to model the response of flexible materials to pressure difference or fluid flow. Each design was tested with pressure difference applied to mimic a normal human breathing pattern and a breathing pattern during an asthma attack. The pressure caused a flow controller vane to bend and deflect, resulting in a greater open area at the highest pressure. The resultant open area was compared to an optimal open area that would restrict flow to resemble a normal breathing pattern. The volumetric flow rate was also determined at various inhalation pressure differences and was compared to a desired rate.
Additional testing was performed to compare the results of the mouth/throat particle deposition (MTPD) in a simple tube model against a more realistic model. Four volumetric flow rates were tested with three particle sizes: 1, 5, and 10 micron diameter aerosol particles. The flow rates were based upon peak and average flow rates of normal and asthma attack cases. The results confirmed that greater flow rates and particle size increase the amount of MTPD.
Prototype models of two different flow controller designs (i.e., air flow regulating members 24 as shown in
Flow rates were measured using a TSI Mass Flowmeter interfaced with Labview. The test results showed that the flow controller could limit asthmatic flow rate as much as 59.83%, reduce MTPD in the upper respiratory regions, and predictably enhance drug delivery in the deeper airways.
In order to create and test the device, two types of studies were conducted. Computer simulations were used to test different vane models to provide predictions of the effectiveness of the device based upon normal and asthma attack breathing patterns. Physical prototypes were also built and tested using equipment such as the TSI Mass Flowmeter. A description of the computational simulations, construction process, and test plan will be discussed below.
A. Simulations
The simulations were conducted following the progression described in the flowchart shown in
Two different vane types were considered as options for the final device. The first model, Vane 1, shown in
Geometries were created for each vane and pipe using ANSYS Design Modeler. The geometry for Vane 1 was generated using only one quarter of pipe, in which the straight edge of the vane closest to the covered half was a fixed support and the other straight edge represented symmetry. The diameter of the pipe was 20 mm, and the diameter of the vane was 19.08 mm. The diameter of the vane was chosen based upon the optimal open area at the lowest pressure difference across the pipe to cause the least amount of particle deposition in the throat. The thickness of the vane was varied in different tests. For the first simulations, the pipe was suppressed and only the vane was considered. A mesh was created for the geometry and was loaded into ANSYS CFX. The vane was defined as being Flexible Dynamic with neoprene rubber material properties. The properties of the neoprene rubber used in construction were not available from the supplier, so the standard neoprene rubber properties in ANSYS were used. The fixed support and the symmetry locations were defined. The other faces of the vane were considered to be a fluid-solid interface, in which the fluid was air surrounding the vane, and the solid was the neoprene rubber of the vane. A negative pressure was applied to one face of the vane, which represented the inhalation. A transient simulation was set up, in which the movement was pressure driven. Under these conditions, the amount of directional deformation along the length of the pipe and deformation in the direction of the radius of the pipe were graphed against the amount of pressure applied. The highest amount of deformation occurred during the highest pressure application. Based upon these deformation dimensions, the amount of open area during the highest pressure could be calculated and compared to the optimal open area at that pressure difference.
The same procedure was performed upon Vane 2 in order to find the deflection needed to achieve the desired open area. During this time, experiments were being performed on the prototype of this model. Experimentation indicated that this design was not as effective in limiting air flow rate, so further study on this vane shape was temporarily suspended.
The next step was to perform a transient analysis on the air flow through the entire pipe using Vane 1 geometry. This analysis would solve for the volumetric fluid flow through the pipe. The resulting data could, in turn, be compared to the optimal flow rate derived from the hybrid breathing curve which was formulated as a suppression of the asthma attack breathing curve to fit the normal. In this case, the vane was suppressed and the body of the pipe was used. In ANSYS, the pipe was divided into three domains. The first domain was the mouth piece, which is the side through which the person would inhale. The middle section was the controller domain. This is the portion of the pipe that contains the vane. The third part of the pipe was the open end that would allow air to enter during the inhalation. As before, the walls, fluid-solid interface, and symmetry were defined. The fluid flowing through the pipe was set to be air at 25° C. The initial conditions were set so that the mouth side would apply a negative pressure (inhalation) following the pressure differences defined in the asthma attack breathing curve. The opening at the opposite end had a pressure of 0 Pascals. The transient analysis was defined; however, when the simulation ran, the mesh at the location of the vane was deformed to the point that a negative volume was created. Obviously, this generated an error, so an alternate method was necessary to provide the results needed.
In order to bypass the problem with the transient analysis, a steady state case could be defined using the whole pipe. The amount of deformation of the vane, which was already determined, could be used to find an angle of deflection (as if the vane remained unbent), which would approximate the open area at the highest pressure difference. In addition, other angles could be tested to see the flow rate if the vane deflected to that degree. Therefore, the geometry was altered so that the vane was in the pipe at an angle and a new mesh was generated.
At the mouth opening, the highest pressure was applied (and made negative) rather than using the transient data. The other end's opening remained at 0 Pa, and all other boundary conditions remained the same as the transient pipe analysis. This simulation was performed with the vane positioned at different angles of deflection, so the volumetric flow rate (Q) through the pipe was determined at four angles of deflection. In the beginning of this study, the need for this project was justified using a simple mouth/throat model designed by Zhang et al. (Zhang, Y., Chia, T. L., & Finlay, W. H. (2006). Experimental measurement and numerical study of particle deposition in highly idealized mouth-throat models. Aerosol Science and Technology, 40(5), 361-372.). Steady state analysis was performed so that three particle sizes (1, 5, and 10 micron diameter aerosol particles) traveled through the model at velocities that mimicked breathing velocities. The purpose of this study was to discover the effect of particle size and velocity on the amount of MTPD rather than lung particle deposition.
The study verified that larger particle size and faster velocities cause greater amounts of MTPD. Recently, a more accurate mouth-throat model was provided by Dr. Kleinstreuer at North Carolina State University. Using this model, similar simulations could be run to determine the legitimacy of the earlier study. In this case, five domains were defined so that MTPD could be quantified in each region: mouth, upper throat, lower throat, epiglottis, and trachea. The inlet was defined as the opening of the mouth, and the outlet was the end of the trachea. In this simulation, the inlet velocity was the condition of the flow, not pressure difference. Four velocities were tested: the maximum and average velocities of asthma attack breathing and normal breathing from the Li et al. study (Li, Z., Kleinstreuer, C., & Zhang, Z. (2007). Particle deposition in the human tracheobronchial airways due to transient inspiratory flow patterns. Journal of Aerosol Science, 38, 625-644). Each velocity was tested at each of the three particle sizes tested previously with steady state and no-slip wall conditions. Because the physical and computational tests were being conducted simultaneously, the volumetric flow rate of a subject inhaling quickly (like an asthma attack breath) uninhibited then through the device were able to be applied to the realistic mouth-throat model. Therefore, experimental data could be tested to determine the actual effectiveness of the physical flexible vane at reducing MTPD.
B. Construction
Prototypes were constructed of the vane types alongside the computational work to select the best design for controlling the air flow rate. The materials and methods used in construction and the prototypes constructed are described below.
Materials
The materials used to build the prototype models (having a construction as shown in
The PVC piping was chosen as the material for the pipe instead of 3D printing the pipe. The rougher surface of a pipe created by 3D printing may have disturbed airflow through the pipe compared to the smooth surface of a PVC pipe. Neoprene rubber was chosen as the material for the flexible membrane due to its high durability, flexibility, and the availability in many thicknesses. The smallest thickness of commercial grade neoprene rubber, 1/32 of an inch, was purchased early in the design phase and proved to be the only product needed due to its ability to limit the air flow rate to the optimal rate.
Working Designs
The first prototype was built using the Vane 2 design for the rubber. The rubber was initially cut using an X-acto Knife, for precision. This method of cutting caused the rubber to have a jagged edge, however, which would potentially be disruptive to the flow. The Vane 2 design was eliminated after testing due to the fact that it did not sufficiently restrict air flow.
The second prototype was built using the Vane 1 design for the rubber using the X-acto Knife. This model was constructed to test the vane shape alone and was not cut to the exact dimensions necessary for significant air flow restriction. There was too much open area in this model.
The third and final models were built using the Vane 1 design for the rubber. This design for the rubber is the most restrictive because it has the highest surface area possible, so that it will not deflect as much as the Vane 2. The final design was built using the minimum open area, 22.06 mm2, determined from computational analysis.
Methods
Construction of a model began with cutting and preparing the PVC piping. The PVC pipe was cut into 4 inch sections using a miter saw. The ends of the piping were then smoothed using a lathe to ensure a smooth contact surface for creating a tight seal and for safety and comfort when testing. This was necessary because a person would be placing his or her mouth around one end of the pipe. A metal file was used to further smooth out the ends of the pipe. In order to interface the TSI Flowmeter, which was used in testing, and the PVC pipe, a one inch section on inner surface of one end of the PVC pipe was filed down using the lathe. The surface was filed just enough to ensure a tight fit between the flowmeter and the pipe.
The PVC pipe coupling initially had a ridge on the inside surface, halfway through the length of the piece. This ridge needed to be removed by filing down the inner surface using a lathe. The outer diameter and inner diameter of the PVC pipe were measured to be 26.5 mm and 20.5 mm, respectively.
A circle of diameter 26.5 mm was drawn on the rubber using a compass. A circle of radius 10.25 mm (R2) was drawn concentric to the first circle. The area of the rubber flap, 142.94 mm2, was determined by subtracting the minimum open area from half of the open area of the inner pipe, 165 mm2. The radius of the flap 9.54 mm was used to draw a semi-circle on the rubber adjacent to the fixed area of rubber which blocks off half of the open area of the pipe. The outer circle was cut out using scissors and then the edge between the inner circle and the rubber flap was cut to create the minimum open area. The rubber edge was glued on both sides to a 4 inch piece of PVC pipe with either epoxy or super glue and was assembled as shown in
The PVC coupling was used to cover the connection between the two four-inch sections of pipe and the rubber to ensure no air leakage at this seal. A pipe clamp secured the device and applied pressure to the connection during the glue drying process. Any material that needed to be further filed away from the surface of the inlet/outlet of the PVC piping was removed using 180-grit fine sandpaper. The final model is as shown in
While the specification has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to, variations of, and equivalents to these embodiments. Accordingly, the scope of the present invention should be assessed as that of the appended claims and any equivalents thereto.
This patent application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 61/373,728 filed on Aug. 13, 2010 and entitled “INHALATION AIRFLOW REGULATION DEVICES AND METHODS OF USING THE SAME,” the subject matter of which is hereby incorporated by reference in its entirety.
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3664337 | Lindsey et al. | May 1972 | A |
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