AEROSOL ENHANCEMENT

Abstract: This invention is a method, and apparatus for an aerosol chamber (300) having an input opening (343), with back pressure created in the chamber by an aperture barrier (360), such as a disk having a plurality of concentric, and circumferential disposed sets of openings (361) to reduce the size of particles applied at the input opening before leaving the output opening (320); which is of lesser diameter than the input opening, which extends to the input opening by an arcuate surface of revolution that serves to redirect interiorly of the chamber aerosol particles that have entered the chamber, and reached the surface of revolution.

Description: AEROSOL ENHANCEMENT This invention relates to aerosol enhancement during fluid flow, and more particularly to the enhancement of therapeutic aerosols. BACKGROUND OF THE INVENTION Therapeutic aerosols, which are colloidal solutions dispensed as a mist, are widely used in medicine. For example, the discharges from inhalation devices such Metered Dose Inhalers (MDI's) deliver medications which desensitise or dilate the bronchial passages and permit air flow from the trachea to the lungs. It often is necessary to relieve breathing difficulties by delivering a measured amount of medication to the site of each difficulty. While oral and intravenous methods can be used, inhalation therapy with MDI's has numerous advantages. The therapeutic effect is more rapid, and a reduced amount of medication usually suffices. In addition, there can be a lower incidence of systemic side effects. In order to operate suitably as a bronchodilator, or expander of bronchial passages, an MDI system must ensure that sufficient medication reaches the lungs. This is accomplished by having the colloidal suspension of an aerosol spray released by an MDI as powder or liquid encapsulated by droplets of propellant. Since the propellant droplets and medicament particles are pressurized, they initially have a rapid discharge velocity. In addition, where the aerosol particles are large and the flow rate is rapid, surface forces tend to agglomerate or increase the droplet and particle sizes. Where the droplets are large, much of the medication impacts the oropharynx at the central portion of the pharynx between the soft palate and the upper portion of the epiglottis, instead of the bronchial passageways extending below the epiglottis. The sensory effect of oropharyngeal impact may be deceptive and lead a patient to believe erroneously that suitable medication has been achieved, even though the desired bronchial site has not been fully medicated. In addition, the localization of medication in the oropharynx can produce adverse side effects when certain aerosols are used, such as those containing corticosteroids. The undesired side effects can include oropharyngeal candidiasis, a mucus infection - or dysphonia, resulting in hoarseness and difficulty in speaking. To have a proper disposition of aerosolized medication in the lungs, rather than in the mouth, it is necessary to coordinate the aerosol discharge by slow and deep inhalation, and by using a breath-hold technique upon completion of inhalation. Otherwise, a reduced amount of aerosol medicament particles are deposited in the lungs with reduced therapeutic effect. In various attempts seeking sufficient aerosolized drug deposits in the lungs, extension devices are provided for attachment to MDI's. These extension devices seek to permit inhalation of only smaller and slower moving particles. One such extension device is disclosed in U.S. Patent 4,706,663 ('663) for PARTICLE CATCHER FOR INHALATION DEVICES, where the catcher is placed directly across the inhalation opening. The '663 catcher is an injection-molded plastic screen formed integrally with, and along the cross section of one end of a flexible support tube. The plastic screen us a structural array of interconnecting elements and openings of a prescribed size to limit the size of particles and droplets passing through the screen. Activation of an MDI aerosol canister discharges a medicinal spray to the screen, and oropharyngeal impaction is said to be reduced because of screen permeation, and accompanied by increased bronchial deposition. However, the combination of extension devices with MDI's can be cumbersome and bulky, often in the form of multi-piece chambers, and cone shaped spacers or collapsible bags, ranging in length to 25 centimeters and in volume to 1000 cubic centimeters. Although size reductions have been attempted by collapsible extension devices, they do not deliver the desired medication unless fully extended. Accordingly, it is an object of the invention to facilitate aerosol medication, particularly in conjunction with metered dose inhalers (MDI's), as well as achieve enhanced medication using a small, portable metered-dose inhaler extension which is easy to use. Another object of the invention is to avoid the need for positioning a screen at a cross-sectional inhalation end , and avoid the need for screen apertures of a prescribed size in order to prevent through-passage of unsuitable droplets. Yet another object is to reduce oropharyngeal impaction while increasing the deposition of aerosolized medicine in the bronchial passageways, and provide an MDI extension which is small, unobtrusive, simple and inexpensive to fabricate. A still further object is to provide inhalation therapy for less coordinated patients comparable to the therapeutic effects achieved by patients with good inhalation skills. SUMMARY OF THE INVENTION In accomplishing the foregoing related objects the invention provides an aerosol extension chamber having an apertured barrier between input and output openings in order to create back pressure against particles applied at the input opening to assist in size reduction before the particles exit at the output opening, with the apertured barrier advantageously located in the chamber at a position of transition between the input opening and the output opening. In accordance with one aspect of the invention, the apertured barrier is a. disk having a plurality of concentric sets of openings which are circumferentially disposed. An opening can be located at the center of the disk. In accordance with another aspect of the invention the aerosol extension chamber has an input end cap at the input opening of the chamber for receiving a raetered aerosol source which has an outlet that is insertable into the end cap through an opening having parallel linear sides bounded by upper and lower curved segments. The parallel sides can extend into the chamber to stabilize the insertion of the metered source outlet and limit the extent to which the aerosol from the source is directed off-axis into the chamber. Outward projections from the input end cap can control the spacing relative to the aerosol source when the extension chamber is positioned on the outlet for the source. The aerosol chamber of the invention can have its housing extended to a lesser diameter by an arcuate surface of revolution, with the arcuate surface serving to redirect interiorally of the chamber aerosol particles that have entered the chamber and reached the surface of revolution. The apertured aerosol barrier advantageously is formed with a plurality of sets of circular openings disposed circumferentially at a plurality of different radii and positioned advantageously in the chamber at a transition from the surface of revolution to the lesser diameter. The circular openings can be of different sizes in different circumferential dispositions, and the openings of a circumferential disposition at a first radius can be smaller than the circumferential openings at a greater radius. A circular opening in the barrier can be positioned to coincide with the central axis of the chamber. In a method of the invention for enhancing the reduction in size of aerosol particles, the steps can include (a) applying an aerosol spray to a chamber having an input opening and an output opening; and (b) creating back pressure curvature redirection in the chamber against the particles of an aerosol spray applied at the input opening in order to reduce the size of particles leaving the output opening. The method can further include the step of applying the aerosol spray to a stabilized opening of the chamber in order to cause the spray to enter the chamber along its central longitudinal axis. The opening of the chamber can be stabilized by extending the side walls of the opening into the chamber. The method also can include the step of removing a cap covering the output opening and placing the cap in a temporary retention position along the side of the chamber in a position that avoids interference with the placement of the chamber into the mouth of a user. In accordance with another aspect of the invention, a one-way valve can be positioned within the extension chamber so that only inhalation at the output opening of the camber, and exhalation is prevented. The one-way valve can take the form of a flap overlying an interiorly located support. BRIEF DESCRIPTION OF THE DRAWINGS Other aspects and advantages of the invention will become apparent after considering several illustrative embodiments taken in conjunction with the drawings, in which: Fig. 1A is a perspective view of aerosol extension chamber in accordance with the invention preparatory to being positioned on an MDI aerosol source? Fig. IB is a partial perspective view showing the extension chamber of Fig. 1A mounted on the aerosol source and operated by the hand of a user to apply small particle medication through the mouth of the user. Fig. 2A is a perspective view of the extension chamber of Figs. 1A and IB with an input end cap separated from the chamber housing and art output end cap shown removed from the outlet end of the chamber housing. Fig. 2B is a perspective view of Fig. 2A showing the input end cap positioned on the chamber housing and the output end cap removed from the output opening, but tethered to the output end of the chamber housing. Fig. 3A is a perspective view of the chamber housing of Fig. 2A showing an apertured barrier positioned at the curved transition from the inlet end to the outlet end. Fig. 3B is an enlarged perspective view showing the input end of the chamber housing and the circumferentially disposed circular apertures of the barrier at the output end of the invention. Fig. 4A is a view of Fig. 2A, partially in phantom, showing the wall thickness of the chamber housing, the internal structure of the input end cap and the structure of the output end cap which can cover the breathing end of the chamber housing. Fig. 4B is an enlarged view of the end cap of the invention with its tether connection to a fastening ring by which the end cap is secured to the chamber housing. Figs, 5A and 5B are enlarged views of the exterior and interior of the input cap for the chamber housing of the invention. Figs, 6A and 6B are partial perspective views of a modification of the chamber of Fig. 2A showing a support of the invention for an umbrella valve shown in Fig. 6C to allow only inhalation operation of the chamber of the invention. DETAILED DESCRIPTION With reference to the drawings, Fig. 1A shows a medication system 100 of the invention formed by an aerosol extension chamber 300 preparatory to being positioned on a Metered Dosage Inhalation (MDI) aerosol source 200. In Fig. IB, the extension chamber 300 has been positioned on the output end 210 of the source 200, and the outlet cap 350 of the chamber 300 has been removed to allow placement of the chamber outlet extension 320 in the mouth of a user U whose hand H is shown depressing a canister 220 which has been inserted into the body 230 of the dispenser 200 to apply aerosol medication. The extension chamber 300 of the invention is used in inhalation therapy to reduce the size and velocity of aerosol particles and droplets sprayed from the dispenser 200, so that an increased amount of dispensed medication is deposited in the respiratory tract of a patient, instead of in the oropharynx above the large central airways of the lungs. The therapeutic efficiency of aerosol therapy is dependent upon ensuring that a, sufficient amount of inhaled medication reaches the lungs. The extension chamber 300 of the invention achieves an enhanced therapeutic effect by creating back pressure within the chamber using a barrier grid with apertures of varying size; also by using a curved shoulder of the chamber to direct larger particles of the aerosol back into the chamber for size reduction, and by using a modified inlet for the chamber, supporting the aerosol source 200 to maintain centralized output flow into the chamber 300. An important aspect of the invention, as described below, is the use of a grid with multiple circular openings in order to optimize the performance of the chamber. As shown in Fig. 2A, the chamber 300 is formed by three sections. A main housing 310 is affixed to an output extension 320 at the position 330 of transition from the maximum diameter Dl of the housing 310 to the reduced diameter D2 of the output extension 320. At the transition 330 there is an apertured barrier 360 (not visible in Fig. 2A) shown in detail in Figs. 3A and 3B and described below. Before being applied to the source 200, the extension chamber 300 has the input end cap 340 secured to the input end of the main housing 310, being guided into position by an alignment groove 311 at the skirt 312 of the housing 310. The groove 311 engages a rib 341-r on the interior wall 342 of the end cap 340 to assure proper positioning of the cap 340 on the skirt 312, as shown in Fig. 2B. In addition, the outlet end cap 350 has the ring 351 positioned on the extension 320 as shown in Fig. 2B on a support hook 314 at an opening 354, so that when the cup 353 is removed from the extension 320, as shown in Fig. 2B, the cup 353 will hang from the tether 352 at the side of the housing 310 and not interfere with user U of Fig. IB. As seen in Fig. 3A, the barrier disk 360 is formed by a circumferential set of apertures at different radii with a central aperture 361 (Fig. 3B) coincident with the axis A of the housing 310, illustratively having a diameter of 0.093 inches. The central opening 361 is surrounded by four sets 362 through 365 of circumferential openings, with the openings of each different set having a different diameter. Thus, the set 362 is formed by nine openings at a radius R2, with each opening having a diameter of approximately 0.045 inches. The next set 363, at a radius R3 includes eleven openings each having a diameter of approximately 0.065 inches, A fourth set 364, at a radius R4 includes sixteen apertures each having a diameter of approximately 0.070 inches. The final set 365, at a radius R5 includes 20 openings each with a diameter of approximately 0.080 inches. " It will be understood that the selected diameters have been found to achieve improved performance for the aerosol chamber 300, but it will be appreciated that other diameters and openings may also be used. Ordinarily, the large droplets and agglomerations of droplets formed upon discharge from the source 200 are dispersed uniformly through the spray medium. In some instances, however, large droplets and agglomerations of droplets become entrained. This effect is reduced due to the construction of the chamber 300. The chamber housing 310 with the extension 320 may be of any medically safe resin or polymer and be formed by injection molding so that a single-piece, homogeneous chamber is produced having the barrier disk 360 integrally formed with, and extending across the interior of the chamber at the transition 330 between the input section 310 and the output section 320. The chamber 300 is preferably made from a chemically resistant plastic. The housing 310 desirably is a copolyester, while the inlet 340 is desirably "santoprene" (thermo-elastic) or polyvinyl chloride (PVC). Flexible material is advantageous for the inlet 340 since that promotes slidable mounting upon, and the support of, a variety of geometrically shaped inhalation mouthpieces. Prior to receiving a dosage of the prescribed medication, the single-piece homogeneous extension chamber 300 is mounted upon the mouthpiece 210 of the inhaler 200 as shown in Figs, 1A and IB. The open end 343 of the input cap 340, opposite the apertured disk 360 is positioned on the mouthpiece 210 of Fig 1A. In order to ensure that the chamber 300 is fixedly maintained in position during the inhalation process, the opening 343, as shown in Figs. 5A and 5B, is proportioned to have side walls 344-a and b, and 345-a and b that correspond to the configuration of the mouthpiece 210. The end cap 340 has a circular recess 341 to accommodate circular mouthpieces. The input cap 340 also has air entrain ent apertures 348 to prevent restriction of end user inhalation flow rate. In addition, in order to avoid o f-axis discharge into the chamber 300, the opposed, parallel and linear side walls 344- a and 344-b extend into the interior of the housing 310. Similarly the opposed arc segments 345-a and 345-b also extend into the interior of the housing 310. Projections 349-a and 349-b in Fig. 5A control the distance between the end cap 340 and the body of the source, such as a metered-dose inhaler. Some sources have the 90 degree configuration as shown in Figs. 1A and IB where the mouthpiece 210 extends at a right angle with respect to the housing 230 of the source 200. However, other sources cut the angle between the housing 230 and the mouthpiece 210 to 45 degrees so that when the source is inserted there is a danger that the mouthpiece will have an upward tilt that directs the input flow off axis. This possibility is avoided by the invention through the use of projections 349-a and 349-b which prevent the mouthpiece from adopting an upward tilt. Unlike the prior art, where the source body can go to the end cap, the projections 349-a and 349-b of the invention increase the internal distance of the source 200 from the apertured disk 360, thus increasing the distance for therapeutic aerosol formation. The additional projections or supports 349-c and 349-d help to prevent the occlusion of air entrainment apertures 348. Further stabilization is provided by the internal structure of the end cap 340 shown in Fig. 5B, where the extended side walls 344-a and 344-b are supported by trapezoidal buffers 346-a and 346-b. Other trapezoidal buffers 347-a and 347- b join the respective arcuate walls 345-a and 345-b, with each buffer 347-a and 347-b having an internal reinforcement rib 347- __.. Of course, the inhalation device upon which the extension chamber 300 may be mounted is not simply limited to a metered-dose inhaler but may also include other inhalation devices, such as dry-powder inhalers or nebulizers, or other similar devices. Subsequent to activation of the aerosol canister 220, a metered dose of medication is dispensed from the mouthpiece 210. As the therapeutic aerosol communicates with the extension chamber 300, back pressure is applied by the internal disk 360, together with a redirection of large droplets by the housing curvature 313 at the transition position 330, so that a stream of appropriately fine particles can reach the lungs of the user. The larger particles and agglomerations redirected into the chamber are either deposited or reduced in size and joined to the outgoing stream. As noted earlier, in order to have proper disposition of aerolosized medication in the lungs, rather than in the mouth, it is necessary to coordinate the aerosol discharge by inhaling slowly and deeply, and by using a breath-hold technique upon the completion of inhalation. Otherwise, a reduced amount of aerosol medicament particles is deposited in the lungs with reduced therapeutic effect. Where patients do not have good inhalation skills, the invention provides inhalation therapy for less coordinated patients, comparable to the therapeutic achieved by patients with good inhalation skills, by adapting the extension chamber 300 to have a one-way valve and valve support at the transition position 330. One way of accomplishing this result is illustrated in Figs. 6A - 6C. In Fig. 6A the barrier disk 360 of Fig. 3A has been replaced by a valve support 660 on which is mounted the umbrella valve 680 shown in Fig. 6C. The valve support 660 is formed by concentric rings 661, 662 and 663 with radial arms 664, 665, 666 and 667 extending from the inner ring 661, which has a positional notch 668. In order to mount the umbrella valve 680 on the support 660, the prong 681 shown in Fig. 6C is inserted into the central opening 671 of the ring 661. This causes the butterfly segments 682 - 685 to lie upon the concentric rings and radial arms of the support 660. It will be noted that the rings 661 - 663 include sector openings 671 and 672 in order to allow aerosol medication to pass through the output opening 320 and to reduce adherence of the segments 682 - 685 on the support 660 during inhalation. The umbrella valve 680 of Fig. 6C is shown having its prong 681 with an axial outer rib 688 to properly position butterfly segment 682 - 685 of the umbrella valve valve 680 onto the support. In order to promote retention of the inserted umbrella valve 680 on the support 660, the prong 681 has a bulbous end 689. The segments 682 - 685 are separated by grooves 684 which extend from the prong 681 to the circumference of the segments 682 - 685. Grooves 687 allow each segment of the umbrella valve to move separately from one another. The structure of the concentric rings 661, 662 and 663, and the radial arms 664, 665, 666 and 667 extending from the inner ring 661, is shown in Fig. 6B as viewed from the insert end of the chamber with the end cap 340 removed. While the rings and arms of Fig. 6A are flat to accommodate the umbrella valve 680, that structure in Fig. 6B has a triangular cross-section in order to promote through-flow and reduce aerosol impaction, while increasing the structural integrity of the support 660 for the umbrella valve 680 on its flat side. It will be appreciated that although the one-way valve 600 of Fig. 6 takes the form of a umbrella valve 680 covering a support 660, other forms of one-way valve may be employed. The serves as a baffle to force the impaction of high velocity non-therapeutic particles that would otherwise end in the mouth. It also will be appreciated that the foregoing embodiments are merely illustrative and other modifications and adaptations of the invention will be apparent to those of ordinary skill in the art.

Claims: What is claimed: 1. Apparatus comprising an aerosol chamber having an input opening and an output opening; and apertured barrier means in said chamber for creating back pressure against particles applied at said input opening in order to redirect flow back into said chamber and reduce the size and velocity of the redirected particles before they leave said output opening. 2. Apparatus as defined in claim 1 wherein said apertured barrier comprises a disk having a plurality of concentric sets of openings which are circumferentially disposed. 3. Apparatus as defined in claim 2 further, including a circular opening at the center of said disk. 4. Apparatus as defined in claim 2 wherein said disk has the same diameter as said output opening. 5. Apparatus as defined in claim 1 wherein said aerosol chamber has an end cap at said input opening for receiving a metered source of aerosol. 6. .Apparatus as defined in claim 5 wherein said metered source is insertable into said end cap through an opening thereof having parallel linear sides bounded by upper and lower curved segments. 7. Apparatus as defined in claim 6 wherein said parallel sides extend into said chamber to stabilize the insertion of said metered source and limit the extent to which the aerosol from said source is applied off axis of said chamber. 8. Apparatus as defined in claim 6 wherein said end cap has projections extending outwardly therefrom to control the spacing of said chamber with respect to said source when positioned thereon. 9. Apparatus comprising an aerosol chamber having an input opening of prescribed diameter extending to an output opening of lesser diameter; and said input opening extending to said lesser diameter by an arcuate surface of revolution; whereby the arc of said surface of revolution serves to redirect interiorly of said chamber aerosol particles that have entered said chamber and reached said surface of revolution. 10. Apparatus as defined in claim 9 wherein an apertured barrier against aerosol particles is positioned in said chamber at a transition from said surface of revolution to said lesser diameter. 11. Apparatus as defined in claim 10 wherein said apertured barrier includes a plurality of sets of circular openings disposed circumferentially at a plurality of different radii of said disk. 12. Apparatus as defined in claim 11 wherein said circular openings are of different sizes in different circumferenti l dispositions. 13. Apparatus as defined in claim 12 wherein the openings of a circumferential disposition at a first radius are smaller than the circumferential openings at a greater radius. 14. Apparatus as defined in claim 10 wherein said apertured barrier includes a circular opening at the central axis of said chamber. 15. The method of enhancing the reduction in size of aerosol particles, comprising the steps of: (a) applying an aerosol spray to a chamber having an input opening and an output opening; and (b) creating back pressure curvature redirection in said chamber against the particles of said aerosol spray applied at said input opening; thereby to reduce the size and velocity of particles leaving said output opening. 16. The method of claim 15 further including the step of applying said aerosol spray to a stabilized opening of said chamber in order to cause said spray to enter said chamber along the central longitudinal axis thereof. 17. The method of claim 16 wherein said opening of said chamber is stabilized by extending the side walls of said opening into said chamber. 18. The method of claim 16 further including the step of removing a cap covering said output opening and positioning said cap along the side of said chamber in a position that avoids interference with the placement of said chamber into the mouth of a user. 19. The method of claim 16 further including the step of operating a one-way valve at said position of curvature redirection; thereby to prevent exhalation into said chamber and permit only inhalation operation in order to adapt said operation to patients that do not have good inhalation skills. 20. The method of claim 16 including the step of applying siad particels to an apertured barrier.

Inventors: MALYS DAVID, PARCO JACK, MALYS, DAVID, PARCO, JACK
Applicants: FERRARIS MEDICAL INC, MALYS DAVID, PARCO JACK, FERRARIS MEDICAL, INC., MALYS, DAVID, PARCO, JACK
Application year: 2000
Main classification: A61M11
IPC codes: A61M11, A61M15, A61M16