Medication delivery apparatus and system having a visual indicator

[0001] This application is a continuation of U.S. patent application Ser. No. 10/431,325, filed May 7, 2003, now U.S. Pat. No. 6,904,908, which claims the benefit of U.S. Provisional Patent Application 60/382,227, filed May 21, 2002, the entire disclosures of which are hereby incorporated herein by reference.

[0002] 1. Field of the Invention

[0003] The present invention relates to a visual indicator for an aerosol medication delivery apparatus and system used for administering a dosage of a substance in aerosol form to a patient.

[0004] 2. Discussion of Related Art

[0005] The use of an aerosol medication delivery apparatus and system to administer medication in aerosol form to a patient's lungs by inhalation (hereinafter “aerosol delivery system(s)”) is well known in the art. As used herein: the term “substance” includes, but is not limited to, any substance that has a therapeutic benefit, including, without limitation, any medication; the term “patient” includes humans and animals; and the term “aerosol delivery system(s)” includes pressurized metered-dose inhalers (pMDIs), pMDI add-on devices, such as holding chambers, devices including a chamber housing and integrated actuator suited for a pMDI canister, nebulizers and dry powder inhalers. Examples of such aerosol delivery systems are disclosed in U.S. Pat. Nos. 4,627,432, 5,582,162, 5,740,793, 5,816,240, 6,026,807, 6,039,042, 6,116,239, 6,293,279, 6,345,617, and 6,435,177, the entire contents of each of which are incorporated herein by reference. Conventional pMDIs typically have two components: 1) a canister component in which the medication particles and a propellant are stored under pressure in a suspension or solution form and 2) a receptacle component used to hold and actuate the canister and having a mouthpiece portion. The canister component typically includes a valved outlet from which the contents of the canister can be discharged. A substance is dispensed from the pMDI by applying a force on the canister component to push it into the receptacle component thereby opening the valved outlet and causing the medication particles to be conveyed from the valved outlet through the receptacle component and discharged from an outlet of the receptacle component. Upon discharge from the canister, the substance particles are “atomized” to form an aerosol.

[0006] In the case of pMDI holding chambers, the holding chambers typically include a chamber housing with a front end and a rear end. The mouthpiece portion of the pMDI receptacle is received in an elastomeric backpiece located at the rear end of the chamber housing. An example of such a backpiece is disclosed in U.S. Pat. No. 5,848,588, the entire contents of which are incorporated herein by reference. The front end of the chamber housing includes an inhalation valve or a containment baffle or both and an interface, such as an adapter, a mouthpiece and/or a mask. The interface can be coupled to the front end of the chamber housing or integrally molded to the front end of the chamber housing. Some holding chambers include an integrated receptacle for a pMDI canister thereby eliminating the need for a backpiece or other equivalent structure used to receive and hold the mouthpiece portion of a pMDI.

[0007] One problem that currently exists with many aerosol delivery systems is that there is a lack of a visual indication to alert a caregiver when a patient is inhaling. In the case of a pMDI used in conjunction with a holding chamber, for example, it is important for a caregiver to know if the patient is inhaling at a rate sufficient to open the inhalation valve to allow the aerosolized medication to exit the holding chamber. It is also important to know when the patient is inhaling in order to coordinate the actuation of the pMDI with inhalation.

[0008] The present invention proposes to overcome the above-described problem, and other problems as described further below, by using a visual indicator in an aerosol delivery system. Such a visual indicator is particularly helpful with patients who do not have established breathing patterns. These patients, such as infants and small children, generally have very low tidal volumes.

[0009] Some known holding chambers on the market maintain that it is possible to determine breathing patterns by looking through the chamber for the movement of the inhalation valve. This is difficult to do in the case of low tidal volumes when the valve will only move a minor amount. If the chamber has an accumulation of drug deposited on the walls then this further impedes the viewing. Several examples of such devices are discussed below. First, U.S. Pat. No. 5,385,140 discloses a holding chamber that has a crosscut valve with four petals that lift during inhalation. At lower tidal volumes the petals will lift a small amount, but this can be difficult to see since there are numerous supporting ribs directly in the line of sight. A second device is disclosed in U.S. Pat. No. 6,039,042 where a clear adapter is used to view breathing patterns by way of the valve. However, the inhalation portion of the valve that moves is directly in the drug pathway and has only slight movement at lower flow rates (approximately 20°). Note that the entire contents of U.S. Pat. Nos. 5,385,140 and 6,039,042 are incorporated herein by reference.

[0010] With some of the other devices on the market it is possible to view the exhalation portion of the breath, but this is not considered to be as important as seeing the inhalation portion. One such device is disclosed in U.S. Pat. No. 6,293,279, the entire contents of which are incorporated herein by reference. The device has a mask with an exhalation valve that moves during exhalation, but at the lower tidal volumes this movement is not obvious.

[0011] Another problem that occasionally occurs, when the interface includes a mask, is a poor seal between the patient's face and the mask. Such a poor seal may adversely affect the delivery of aerosolized medication to the patient. The use of the above-mentioned visual indicator would be helpful in alerting the caregiver to verify whether there is a poor seal between the patient's face and the mask and, if so, to readjust the mask on the patient's face to improve the seal.

[0012] One aspect of the present invention regards a delivery system that includes a chamber that contains a substance in an interior volume of space formed within said chamber and an opening that receives the substance located in said volume of space and introduces the substance to a downstream path upon which the substance primarily flows along. An interface that receives the substance from the opening, the interface has a viewing port that prevents substantially non-ambient atmosphere gases and substances from escaping therefrom and that allows visualization of an internal portion of the interface. A flow indicator is positioned within the interface so as to be viewed via the viewing port and is positioned so as to not substantially interfere with a flow of the substance along the path.

[0013] A second aspect of the present invention regards a method of determining whether a patient is inhaling or exhaling when using a delivery system, the method including dispensing a substance located within an interior volume of a delivery system so that the substance will primarily flow along a path within the delivery system after being dispensed. Observing a position of a flow indicator located within the delivery system and located so as not to substantially interfere with the substance flowing along the path. Determining whether a user of the delivery system is inhaling from the delivery system based on the observed position of the flow indicator.

[0014] A third aspect of the present invention regards a flow indicating system that includes a conduit that contains a substance, wherein the conduit defines a path along which the substance primarily flows and a viewing port attached to the conduit and the viewing port that prevents substantially non-ambient atmosphere gases and substances from escaping therefrom and allows visualization of an internal space defined by the viewing port. A flow indicator that is positioned within the conduit so as to be viewed via the viewing port and is positioned so as to not to substantially interfere with a flow of the substance along the path.

[0015] Each aspect of the present invention provides the advantage of assisting either the patient or a third party caregiver to determine when the patient is inhaling when using an aerosol delivery system so that the patient or third party caregiver can be alerted to possible causes affecting inhalation, such as an improper seal between the patient's face and the aerosol delivery system's interface, such as a mask.

[0016] Each aspect of the present invention provides the advantage of allowing a user or caregiver to observe when inhalation has begun so that the drug can be properly administered.

[0017] The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings.

[0063] FIGS. 1–11, 16–21 and 25–29 show an embodiment of an aerosol delivery system 100. The system 100 includes a holding chamber or conduit 102, an interface 104, a retaining disc 116, an inhalation valve 132 and a source of a substance, such as a pMDI canister 106, attached to the rear end of the holding chamber 102.

[0064] As shown in FIGS. 1–4 and 27–34, the holding chamber 102 includes a chamber housing 108 that has a generally cylindrical cross-sectional shape that defines an interior volume of space for receipt therein of aerosolized medication from the pMDI 106. A front end of the chamber housing 108 includes a dome-shaped head piece 110 that includes a central circular opening 112 that is in fluid communication with the interior volume of space of the chamber housing 108. The opening 112 defines the periphery of a flow path as it exits the opening. The head piece 110 further includes a plurality of engagement tabs 113, whose function will be described below. A rear end of the chamber housing 108 is attached to a detachable and flexible backpiece 114 that includes an opening (not shown) suited to receive the mouthpiece portion of the pMDI receptacle that houses the pMDI canister. The backpiece 114 preferably is substantially the same as the backpiece disclosed in U.S. Pat. No. 5,848,588. Examples of possible pMDI adapters and canisters to be used in conjunction with the holding chamber 102 are also described in U.S. Pat. Nos. 5,012,803, 5,012,804, 5,848,588 and 6,293,279, the entire contents of each of which is incorporated herein by reference.

[0065] When a force is applied to the stem of the pMDI canister a portion of the substance is discharged from the discharge end of the pMDI receptacle in aerosol form into the chamber housing 108. The aerosol medication particles within the chamber housing 108 are withdrawn therefrom by having the patient inhale through the interface 104 in the manner described below.

[0066] The pMDI canister contains a substance, preferably a medication suspension or solution under pressure. In the present embodiment, the substance dispensed is an HFA propelled medication suspension or solution formulation. Other propellants, such as CFC may also be used. It should be pointed out that while the described embodiments regard an aerosol delivery system for the delivery of an aerosolized medication from a pMDI, other aerosol delivery systems are contemplated that can be used within the spirit of the present invention. For example, it is contemplated that a visual indicator can be incorporated with an aerosol delivery system such as existing ventilator systems, dry powder inhalers and nebulizers, in a manner similar to that described below. Examples of nebulizers that can be adapted to include a visual indicator are disclosed in U.S. Pat. Nos. 5,823,179 and 6,044,841, the entire contents of which are incorporated herein by reference.

[0067] The present invention is not limited to the treatment of human patients. For example, it is contemplated that a visual indicator can be incorporated in a mask for administering medication to animals, including for example and without limitation equines, cats, dogs, etc. An example of an equine mask is disclosed in U.S. Pat. No. 5,954,049, the entire contents of which are incorporated herein by reference. With such aerosol delivery systems in mind, the variety of medications that can be dispensed by aerosol delivery systems that employ a visual indicator in accordance with the present invention is increased.

[0068] As shown in FIG. 4, a retaining disc 116 is positioned before the opening 112 at the front end of the chamber housing 108. The retaining disc 116 may be integrally attached to the chamber housing 108 or releasably attached as shown in FIG. 4. As shown in FIGS. 4 and 25–26, the retaining disc 116 includes an annular ring 118 that surrounds an opening 120. Four linear appendages 122 extend inwardly from the annular ring 118 and are attached to a circular dome portion 124. The annular ring 118, the appendages 122 and the dome portion 124 define an inhalation opening area 126 that includes four openings 126A–126D. The openings 126A–D are arcuate in shape. The openings have an inner radius of approximately 10 mm and an outer radius of approximately 18 mm. Each opening has an arcuate length of 4 mm. The size, shape and number of openings may vary depending on the medication and/or propellant used. The retaining disc 116 is preferably made of a rigid material, such as a metal or plastic, preferably propylene or polycarbonate. As shown in FIGS. 4, 25 and 26, the retaining disc 116 includes a semi-circular stop 117 whose operation will be explained below. Other examples of possible retaining discs are disclosed in U.S. Pat. No. 6,293,279, the entire contents of which are incorporated herein by reference. The annular ring 118 is attached to the front end of the chamber housing 108 so that the openings 112 and 120 are concentric and overlap one another.

[0069] The center portion of the retaining disc 116 includes a containment baffle positioned so as to partially block the opening 112. The retaining disc 116 reduces the velocity or flow rate or both of the aerosol medication particles flowing along the axis 128 of the chamber housing 108. The circular dome portion 124 of the retaining disc 116 is aligned with the central axis 128 of the chamber housing 108 and is directly in line with the opening 112. Aerosol medication particles that have a flow path away from the central axis 128 tend to have a velocity that is lower than that of particles near to the axis 128. The dome portion 124 of the retaining disc 116 reduces the forward, on-axis velocity and simultaneously acts as an impaction surface for on-axis projectile aerosol medication particles and so protects the duckbill valve 132. At the same time, the dome portion 124 allows slower moving aerosol medication particles to migrate towards the sides 130 of the chamber housing 108. The forward velocity of the aerosol medication particles away from the axis 128 along the chamber length is also reduced by the annular ring 118 of the retaining disc 116. It should be understood that the dome portion can alternatively be formed with a flat surface facing the rear end, or a curved surface, for example a convex or concave surface.

[0070] As shown in FIG. 4, a duckbill valve 132 is seated on the front surface of the annular ring 118. The duckbill valve 132 is generally well known in structure having a top surface 134 and a bottom surface 136. The surfaces 134 and 136 open and close with respect to each other in a well-known manner so as to allow or prevent gas to flow through the valve 132. The duckbill valve 132 preferably is a 19 mm valve made of a soft plastic, such as silicone or a thermoplastic elastomer. It should be understood that other valves, including for example and without limitation, center post valves, slit petal valves and valves having a central opening with a peripheral sealing edge.

[0071] On the top portion of the duckbill valve 132, a visual flow indicator 138 is integrally attached to a top portion of the outer circumference of the duckbill valve 132. The visual flow indicator 138 is rectangular in shape, although other shapes, such as a square or an ellipse, may also be suitable. For example, the visual flow indicator 138′ may have a rounded top edge as shown in FIGS. 22–24. The rectangular and rounded visual flow indicators 138, 138′ each may have a length of 5 mm to 20 mm, preferably a length between 7 mm and 11 mm, and most preferably a length of 8.5 mm, a width of 5 mm–20 mm, preferably 8 mm to 12 mm, and most preferably 10 mm, and a thickness of 0.1 to 2 mm, preferably 0.15–1 mm, and most preferably 0.25 mm. The length of the visual flow indicators 138, 138′ are measured from a hinge area (not shown). With this in mind, the sensitivity of the visual flow indicators 138, 138′ is a function of the length of the indicator, wherein as the indicator becomes longer it becomes more sensitive to detecting flow. The operation of the visual flow indicators 138, 138′ will be described in more detail below.

[0072] The flow indicator can be integrally formed with the valve or it can be made as a separate member. The indicator 138, 138′ is hingedly connected to the valve with a living hinge formed at the junction thereof as shown for example in FIGS. 16 and 22, or it can be hingedly connected with a pin 139 as shown in FIG. 45. The resiliency of the indicator 138, 138′ biases the indicator to an at rest position. However, it should be understood that auxiliary springs can be configured to act on the indicator to bias it to the at rest position.

[0073] As described above, the chamber housing 108, retaining disc 116 and duckbill valve 132 define a holding chamber 102. The holding chamber 102 is attached to a patient interface 104, although a patient interface integrally molded with the front end of the chamber housing 108 would also be suitable. In one embodiment, the patient interface 104 includes an adapter 140 and a mask 144 with exhalation valve 142. Other patient interfaces may include for example and without limitation, various mouthpieces, masks, endotracheal tubes, etc. As shown in FIGS. 4–11, the adapter 140 includes an annular attachment collar 146 with slots 148, a transition piece 150 and a cylindrical exit port 152. The adapter 140 is attached to the chamber 108 by snap inserting the tabs 113 of the chamber housing 108 into the slots 148 and then twisting the chamber housing 108 or adapter 140 so that the tabs 113 are locked into place within the slots 148. Once the chamber housing 108 is attached to the adapter 140, the duckbill valve 132 and the flow indicator 138, 138′ are positioned within the transition piece 150. In particular, the flow indicator 138, 138′ is positioned within a raised viewing port area 154 of the transition piece 150. Since the adapter 140 with its transition piece 150 and raised viewing port area 154 are each made of a clear rigid plastic, such as polycarbonate or a co-polyester, the movement of the flow indicator 138, 138′ is visible to a user at all times. In another variation, the viewing port area 154 is formed in the collar 146 and the indicator 138, 138′ is positioned therein.

[0074] As explained above, the retaining disc 116 is positioned at the front end of the chamber housing, and can be integrally attached thereto or releasably detached, for example by disposing it between the chamber housing and the adapter 140. In one embodiment, shown in FIGS. 43 and 44, the retaining disc 116 is releasably connected to the adapter 140, or other patient interface component. In one embodiment, a plurality of tabs 123 are formed on the interior of the adapter and engage the outer peripheral edge of the annular ring 118 in a snap-fit engagement. In other embodiments, the retaining disc is integrally molded with the adapter or other patient interface component, or is secured thereto by bonding, fasteners and other similar devices. In this way, the retaining disc 116, and the valve 132 that is seated thereon between the adapter and the retaining disc, remain coupled to the adapter 140, or other similar component secured to the end of the chamber housing, upon its removal, for example when cleaning the device. Accordingly, the risk of losing the retaining disc 116 and/or valve 132 is reduced.

[0075] Note that an alternate embodiment of an adapter is shown in FIGS. 12–15. The adapter 140′ has similar dimensions and elements as the adapter of FIGS. 5–11. Operation and attachment are similar as well. One difference is the shape of the viewing port area 154′ in which the indicator 138, 138′ is positioned.

[0076] An exhalation valve 142 is inserted into an exit port formed in the nasal reception area 160 of the mask 144 and attached thereto. Examples of such a mask and exhalation valve are disclosed in U.S. Pat. Nos. 5,988,160 and 5,645,049, the entire contents of each of which are incorporated herein by reference. A cylindrical input port 156 of the mask 144 is placed over the exit port 152 of the adapter 140, 140′ and attached thereto by a friction fit.

[0077] With the above description of the structure of the aerosol delivery system 100, the operation of the system 100 can be readily understood. In particular, a patient places his or her face within the interior 158 of the mask 144 so that his or her nose is positioned within the nasal reception area 160. In other embodiments, the patient or caretaker arranges the patient interface, such as a mouthpiece or endotracheal tube in appropriate registration with the user. The patient or caretaker then presses the pMDI canister within the pMDI adapter of the pMDI 106 attached to the backpiece 114 located at the rear end of the chamber housing 108, which causes the medication to be delivered in aerosol form to the opening 112 in the manner described previously.

[0078] At or just after the time of depressing the pMDI canister, the patient inhales. During proper inhalation, the visual flow indicator 138 will pivot forward in response to the inhalation pressure by an angle θ of between 25° to 45°, and preferably 45°, and seal against a surface 162 on the adapter 140, 140′ as shown in FIGS. 3 and 33–34. The angle θ can be varied to take into account the attributes of the patient, i.e., child v. infant. Note that the visual flow indicator 138 has minimal resistance, due to its size and shape, and will respond to low tidal volumes, which is ideal for infants (tidal volume of approximately 50 cc, flow rate approximately 5 lpm) and small children (tidal volume ranging from approximately 150 to 250 cc, flow rate approximately 12 lpm). The movement of the visual flow indicator 138, 138′ against surface 162 creates a seal that will prevent entrainment of ambient air. A caregiver who directs his or her attention to the viewing port area 154, 154′ will be able to see the movement of the flow indicator 138, 138′ as it forms the seal and so will become aware that inhalation is occurring or has occurred. Also during inhalation, the duckbill valve 132 will open thereby allowing the aerosolized medication to exit the chamber housing 108 and be introduced by the opening 112 to a downstream path upon which the medication flows along so as to eventually be inhaled by the patient. As shown in FIGS. 2 and 31–34, the flow indicator 138, 138′ is positioned above the duckbill valve 132 and outside the periphery of opening 112, and so is outside of the medication dispensing pathway, and thus does not compromise medication delivery. Note that the introduction of the medication to the pathway through the opening 112 can be caused by either external or internal forces.

[0079] Once the patient exhales or ceases to inhale, the flow indicator 138, 138′ will pivot back to its original vertical position until it engages the stop 117 as shown in FIGS. 31–32. The resiliency of the indicator 138, 138′ pivots or biases the indicator to the at-rest position. Again, a caregiver who directs his or her attention to the viewing port area 154, 154′ will be able to see the return movement of the flow indicator 138, 138′ and so will become aware that exhalation has occurred. Besides alerting the caregiver that inhalation or exhalation is occurring or has occurred, the movement of the flow indicator gives the caregiver confidence that, where the patient interface includes a mask, a proper seal is formed between the patient's face and the mask 144.

[0080] Note that the flow indicator 138, 138′ does provide a pathway which is in fluid contact with ambient air located within the viewing port area 154, 154′ rearward of the flow indicator 138, 138′. The pathway includes a rearward opening or an opening formed in the rearward top portion of the viewing port area 154, 154′, such that the flow indicator 138, 138′ is drawn off of the stop. However, the flow indicator 138, 138′ seals against surface 162 to prevent the entrainment of ambient air as described above.

[0081] The primary pathway for exhaled gases is through the exhalation valve 142 located in the mask 144 as shown in FIG. 30. In particular, the stop 117 and flow indicator 138, 138′ extend so as to substantially block all exhaled gases from escaping via the viewing port while allowing ambient air to flow therein. Similarly, the stop 117 and flow indicator 138, 138′, which is registered against surface 162 upon inhalation, substantially blocks the dispensed substance from exiting the delivery system via the viewing port area. Accordingly, the stop 117 and flow indicator 138, 138′ substantially prevents non-ambient gases and substances from escaping from the delivery system via the viewing port area. Note that the stop 117 may be removed so as to allow the viewing port area to act as a two-way valve that allows ambient atmosphere to enter and exhalation gases to exit therefrom.

[0082] An alternative embodiment of an aerosol delivery system is shown in FIG. 35. The aerosol delivery system 200 is the same as the aerosol delivery system 100 of FIGS. 1–11, 16–21 and 25–29 except that the holding chamber and the patient interface have been altered as shown in the drawings and as described herein. Accordingly, like elements will retain like numerals. With this in mind, the holding chamber or conduit 202 has a backpiece 114 attached to a rear end of the chamber housing 108. An opening of the backpiece 114 receives a discharge end of an adapter (not shown) that houses the pMDI canister. The holding chamber 202 further includes a retaining disc 216 that is integrally attached to a front end of the cylindrical chamber housing 108. The retaining disc 216 includes an annular ring 218 that surrounds an opening 220. Eight linear appendages 222 extend inwardly from the annular ring 218 and meet at a center hub 223. The annular ring 218, the appendages 222 and the center hub 223 define an inhalation opening area 226 that includes eight openings. The size, shape and number of the openings may vary depending on the medication and/or propellant used.

[0083] As shown in FIG. 35, a petal valve 232 is attached to the front surface of the annular ring 218. In particular, pegs 233 integrally formed on the annular ring 218 are snugly inserted into corresponding openings 235 formed in the petal valve 232. The operation of the petal valve 232 is well known in the art. The petal valve is preferably made of a material similar to that of the duckbill valve 132. On the top portion of the petal valve 232, a visual flow indicator 138, 138′ is integrally attached to a top portion of the outer circumference of the petal valve 232.

[0084] The holding chamber or conduit 202 is attached to an interface similar to the interface 104 shown in FIGS. 1–11, 16–21 and 25–29. The interface of the embodiment of FIG. 35 differs from the interface 104 in that a shorter adapter 240 is used, which includes a cylindrical exit port 252 that can function as a mouthpiece. Alternatively, the adapter 240 can be attached to an exhalation valve and a mask (not shown) in the manner described with respect to FIGS. 1–11, 16–21 and 25–29. As shown in FIG. 35, the adapter 240 includes an annular attachment collar 246 with slots 248, a transition piece 250 and a cylindrical exit port 252. The adapter 240 is attached to the chamber housing 108 by snap inserting tabs 212 of the chamber housing 108 into the slots 248 and then twisting the chamber housing 108 or adapter 240 so that the tabs 212 are locked into place within the slots 248. Once the chamber housing 108 is attached to the adapter 240, the petal valve 232 and the flow indicator 138, 138′ are positioned within the transition piece 250. In particular, the flow indicator 138, 138′ is positioned within a raised viewing port area 254 of the transition piece 250. The adapter 240 with its transition piece 250 and raised viewing port area 254 are each made of a clear rigid plastic, such as polycarbonate or a co-polyester. The chamber housing 108 can also be made of a clear material, such as a rigid plastic. Thus, a caregiver is able to visualize the movement of the visual flow indicator 138, 138′ within the adaptor 240 and is able to detect whether inhalation is being performed or a proper seal is present in the same manner as with the aerosol delivery system of FIGS. 1–11, 16–21 and 25–29. The adapter can also include a stop member that interfaces with the flow indicator.

[0085] In each of the embodiments shown in FIGS. 1–35, the visual flow indicator 138, 138′ is integrally attached to its corresponding valve. It should be pointed out that such integral attachment is not necessary. For example, it is possible to take a separate piece of material in the shape and composition of indicator 138, 138′ and attach one end to a portion of the adapter so that a free end of the material lies within the viewing port. Attachment can be accomplished by inserting the one end between two ridges formed in the adapter and gluing the end therebetween.

[0086] Another example of where the visual flow indicator is not attached to a valve is shown in FIG. 36. In this embodiment, a visual flow indicator 338 is attached to an aerosol delivery system 300 similar to the one disclosed in U.S. Pat. No. 6,293,279. One difference is that the chamber housing 308, attached to the canister holding portion 309, includes a transparent viewing port 354. In an alternative embodiment, the view port can be formed on the downstream portion 311 of the delivery system. The visual flow indicator 338 is attached to either the chamber housing 308 or the downstream portion 311 that includes the mouthpiece 313 via a snap fit. The visual flow indicator 338 preferably has a shape and a structure similar to that of the visual flow indicators 138, 138′ described previously so as to have a similar range of motion. In operation, the chamber housing 308 acts as a conduit of the substance as it travels to the mouthpiece 313.

[0087] Other variations for the visual flow indicator are also possible. For example, the viewing port area can be positioned elsewhere on the adapters 140, 240, the chamber housing 308 and the downstream portion 311 and the corresponding visual flow indicator is positioned so as to be viewed from the viewing port area. In the case of the aerosol delivery system of FIGS. 1–11, 16–21 and 25–29, the viewing port area can be moved to the side of the adapter 140 in the manner shown in FIG. 37. In such a case, the corresponding visual flow indicator 138, 138′ is moved to a side of the duckbill valve 132 that faces the viewing port area 154, 154′.

[0088] FIGS. 38–42 show the present invention used in aerosol delivery systems such as dry powder inhalers and nebulizer systems. In the case of dry powder inhalers, a dry powder inhaler 400 includes a chamber housing 402 that contains a dry powder as shown in FIGS. 38 and 39. The chamber housing 402 is similar to the chamber housing disclosed in U.S. Pat. No. 4,627,432, the entire content of which is incorporated herein by reference. Other dry powder inhalers that can incorporate a flow indicator are disclosed for example and without limitation in U.S. Pat. No. 6,116,239, which is hereby incorporated herein by reference. The chamber housing 402 includes a circular bottom opening 404 and a top opening 406 that is in fluid communication with ambient air. An interface which includes a conduit or mouthpiece 408, is attached to the bottom opening 404 so that the mouthpiece 408 is in fluid communication with the interior of the chamber housing 402. Attached to the mouthpiece 408 is a transparent viewing port area 410. Within the viewing port area 410, a visual flow indicator 412 is positioned. The visual flow indicator 412 has a rear, lower slot (not shown) that receives a ridge 414 formed below the top opening 406. Once the ridge 414 is received in the rear slot, the visual flow indicator 412 is permanently attached to the ridge 414 by using an adhesive.

[0089] In operation, the patient activates the chamber housing 402 to provide access to the dry powder within by having the patient inhale through the mouthpiece 408. Upon inhalation, the dry powder substance within the housing 402 is introduced by the opening 404 to a downstream path along which the substance travels through the interface and the mouthpiece 408 to reach the patient. During inhalation the upper part of the visual flow indicator 412 will pivot downward to a horizontal position. If the patient is not inhaling or fails to inhale above a specified rate of inhalation, the upper part of the visual flow indicator 412 will remain in a vertical position blocking top opening 406. The range of motion of the visual flow indicator 412 is preferably the same as that of the visual flow indicators 138, 138′ and 338 mentioned previously.

[0090] A visual flow indicator can also be used in nebulizer systems. A nebulizer 500 includes a chamber housing 502 that contains a liquid substance as shown in FIGS. 40–42. The chamber housing 502 is similar to the chamber housing disclosed in U.S. Pat. No. 5,823,179. The chamber housing 502 includes a rectangular-like exit port 504 that includes an opening (not shown). An interface includes an adapter 506 that is attached to the exit port 504 so as to be in fluid communication with the interior of the chamber housing 502. The interface also includes a mouthpiece 508 which is attached to the adapter 506 so that the mouthpiece 508 is in fluid communication with the interior of the chamber housing 502 via adapter 506. Attached to the adapter 506 and mouthpiece 508 are transparent housings 510, 512, respectively. When the mouthpiece 508 is attached to the adapter 506 a transparent viewing port area 514 is formed. Within the viewing port area 514, a visual flow indicator 516 is positioned. The visual flow indicator 516 has a pair of lower slots 518 that receive a pair of ridges 520, 522 formed within the mouthpiece 508. Once the ridges 520, 522 are received in the slots 518, the visual flow indicator 516 is permanently attached to the ridges 520, 522 by using an adhesive.

[0091] In operation, the patient activates the storage unit 502 by inhaling through the mouthpiece 508. Upon inhalation, the liquid within the housing 502 is introduced by the opening (not shown) of the exit port 504 to a downstream path along which the substance travels through the interface and the mouthpiece 508 to reach the patient. Thus, the interface 506 and mouthpiece 508 each operate as conduits for the inhaled substance. During inhalation the upper part of the visual flow indicator 516 will pivot downward to a horizontal position. If the patient is not inhaling or fails to inhale above a specified rate of inhalation, the upper part of the visual flow indicator 516 will remains in a vertical position blocking an opening of the housing 510. The range of motion of the visual flow indicator 516 is preferably the same as that of the visual flow indicators 138, 138′, 338 and 412 mentioned previously.

[0092] As described previously, a visual flow indicator according to the present invention can be used in a variety of aerosol delivery systems. In each of the described systems, there is a common way to explain the present invention to encompass each of the previously described aerosol delivery systems. In particular, the aerosol delivery systems can each be thought of as containing a flow indicating system where the portion of the delivery system, such as an interface or a chamber housing, that is attached to the view port area is deemed a conduit. The conduit defines an interior space along which a substance, such as an aerosolized medication, primarily flows along a flow path defined within the interior space. The flow indicating mechanism includes a flow indicator, such as the flow indicators described in FIGS. 1–42, that is positioned within the conduit so as to be viewed via the viewing port, but is positioned substantially outside of the flow path so as to not to substantially interfere with the flow of the substance along the interior space.

[0093] The embodiments of the invention disclosed herein are presently considered to be preferred, various changes and modifications can be made without departing from the spirit and scope of the invention. As noted, the discussion above is descriptive, illustrative and exemplary and is not to be taken as limiting the scope defined by any appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.