WO2001028614A1

WO2001028614A1 - Capillary feed nebulizers having through channels in the capillary feed plate

Info

Publication number: WO2001028614A1
Application number: PCT/US2000/027951
Authority: WO
Inventors: Chau B. Tran
Original assignee: Hudson Respiratory Care Inc
Current assignee: Teleflex Medical Inc
Priority date: 1999-10-15
Filing date: 2000-10-11
Publication date: 2001-04-26
Anticipated expiration: 2002-04-15
Also published as: AU1076601A

Abstract

A capillary feed nebulizer incorporates a capillary feed plate having a plurality of channels extending along the plate between the top and bottom plate surfaces.

Description

CAPILLARY FEED NEBULIZERS HAVING THROUGH CHANNELS IN THE CAPILLARY FEED PLATE

Background of the Invention

Flat bottom capillary feed nebulizers have an advantage over other capillary feed respiratory nebulizers in delivering aerosol while being held at an angle or tilted from vertical with little or no interruption of liquid flow from the liquid reservoir to the gas mixing chamber. For example, the Hudson RCI Mιcromιst^w Small Volume Nebulizer is a capillary feed nebulizer designed to deliver a fine, dense mist at any angle up to 90° tilt from vertical. Such a feature allows the clinician to administer medications to patients with special treatment requirements which may cause the nebulizer to be tilted at an angle relative to vertical The aforesaid nebulizer is described in U.S. Patent No. Re 33,642

In spite of the normally efficient operation of the above described nebulizer, it is found that when the device is used in a generally vertical position, near the end of the treatment a small volume of liquid often remains in the reservoir on the flat upper surface of the collection flange or capillary feed plate and will not be drawn into the capillary feed passageway unless the therapist strikes or shakes the nebulizer. Although such action is inconvenient and may interrupt the treatment, failure to do so could result in a substantial loss of medication delivered to the respiratory patient It is to the elimination of the above described problem that the improved capillary feed nebulizer of the present invention is directed

Summary of the Invention The improved capillary feed nebulizer of the present invention incorporates a capillary feed plate having a plurality of channels extending along the upper and lower plate surface and communicating the liquid holding chamber of the nebulizer jar with the capillary feed passageway These channels provide sufficient paths for liquid medication which could otherwise remain on the upper surface of the capillary feed plate as previously described.

Brief Description of the Drawings Fig 1 is a side elevational view of the nebulizer of the invention illustrating the relationship of the assembled spray nozzle and capillary feed plate,

Figs. 2 and 3 are upper and lower perspective views, respectfully, of an integral spray nozzle and channeled capillary feed plate of the invention; and

Figs. 4 and 5 are top plan views of capillary feed plates showing examples of alternative channel design embodiments. Detailed Description of the Invention

Reference is made to Fig. 1 illustrating the assembled liquid and gas directing components of a capillary feed nebulizer of the invention The general structure and features of the capillary feed components of the device are similar to those disclosed and shown in U.S Patent Re. 33,642 These basic components include a gas pipe 17 which extends downwardly from bottom plate 15 and gas nozzle 18 The gas pipe will be connected to a gas supply tube when the nebulizer is in use. A nebulizer jar 11 includes a sidewall 14, the upper portion of which defines a liquid holding chamber 20 Sidewall 14, bottom plate 15, gas nozzle 18 and gas pipe 17 may be integrally formed and molded as one piece, or two or more of the components independently formed and assembled, using adhesives or otherwise bonded together such as by ultrasonic bonding or other techniques known in the art Preferably, the components are conveniently molded as one piece using a thermoplastic resin such as polypropylene, polyethylene, polyvmyl chloride, or other equivalent and suitable polymers or plastics

In the embodiment illustrated, gas nozzle 18 extends along a substantially vertical axis from the plane of bottom plate 15, the latter illustrated as a flat plate extending along a plane normal to the gas nozzle axis Alternatively, bottom plate 15 may be slanted upwardly or downwardly from such a normal plane relative to the axis of gas nozzle 18, preferably at an angle of J- about 30°, and preferably of less than about ± 15° Moreover, the bottom plate need not be flat or planar, but may be curved or arched along its upper surface. However, preferably the upper surface of the bottom plate is substantially flat, more preferably lying along a plane substantially normal to the central axis of gas nozzle 18.

Observing also Figs 2 and 3, the spray nozzle 30 and capillary feed plate 32 are illustrated Preferably, the two components are integrally formed, such as by a single molding operation using a suitable thermoplastic such as previously described or they may be separately formed and assembled using adhesive or ultrasonic welding or similar and equivalent techniques known in the art. The shape of the interior surface of the spray nozzle 30 is such that when the spray nozzle is assembled to overlie gas nozzle 18 as shown in Fig. 1 , a liquid flow passageway 21 is provided for directing liquid supplied from the liquid holding chamber to a gas/liquid mixing chamber 23. The interior surface of spray nozzle 30 may be cylindrical and spaced apart from the outer surface of gas nozzle 18 along its entire length, or either or both of the two surfaces may be formed to create a plurality of fluid passageways. For example, the interior surface of spray nozzle 30 may have one or more surfaces which contact the exterior surface of gas nozzle 18 thereby creating a plurality of fluid passageways along a portion or all of the length between the two surfaces However, regardless of whether there is one continuous flow passageway or a plurality of such passageways, the passageway dimensions will be such that liquid will be drawn upwardly along liquid flow passageway 21 to the mixing chamber 23 when gas is supplied to gas pipe 17 and forced through gas port 13, across mixing chamber 23 and out through spray port 19. Such a function and performance of the components, as well as the spacing required between the gas nozzle and spray nozzle component, will be understood by those skilled in the art and are described and illustrated in U.S. Patents Re 33,642 and 4,588,129

The bottom surface 35 of capillary feed plate 32 overlies the upper surface 22 of bottom plate 15 to form a capillary feed passageway 33 therebetween. Preferably, the lower surface 35 of the capillary feed plate 32 is parallel with the upper surface 22 of bottom plate 15 so that the capillary feed passageway 35 is substantially uniform in its dimension between the two surfaces. However, some variation other than parallel surfaces is acceptable, so long as a capillary feed of the liquid along the capillary feed passageway is provided and maintained during operation of the nebulizer. The angle between the plane along which capillary feed plate 32 lies relative to the central axis of spray nozzle 30 will preferably be the same as the relative angle between the plane of bottom plate 15 and the central axis of gas nozzle 18 Moreover, as is shown in Fig 1 , the gas nozzle and spray nozzle are coaxial when assembled Accordingly, most preferably, a capillary feed plate lies along a plane normal to the central axis of spray nozzle 30, or along a plane at an angle of i 30° or less and preferably less than t 15° from the axis of spray nozzle 30. Where bottom plate 15 is flat and lies along a plane normal to the axis of gas nozzle 18, then capillary feed plate 32 also preferably lies along a normal plane relative to the axis of spray nozzle 30. Moreover, where the upper surface of the bottom plate is curved or arched, the bottom surface of the capillary feed plate is also curved or arched. Similarly, any departure of the angle of the plane of bottom plate 15 relative to the axis of a gas nozzle will be reflected in the angle of the plane of capillary feed plate 32 relative to the axis of spray nozzle 30, whereby the upper surface of bottom plate 15 and lower surface of capillary feed plate 32 are substantially parallel to define a substantially uniform capillary feed passageway as previously described

In operating the capillary feed nebulizer of the invention, gas is directed into gas pipe 17 from an external gas source, not shown, and upwardly through the pipe into the interior of gas nozzle 18. From there the gas passes through the gas port 13, and across mixing chamber 23 to create an aerosol which is forced out of spray port 19. The liquid medication to be nebulized is charged into liquid holding chamber 20. As gas is forced through port 13 and aerosol through port 19, a vacuum is created in mixing chamber 23 causing liquid to rise along passageway 21. The liquid is supplied from chamber 20 through liquid flow inlet 26, slot 31 and capillary feed passageway 33. The liquid flow inlet 26 is defined between the edge of capillary feed plate 32 and the nebulizer jar sidewall 14 which defines the liquid holding chamber 20.

Observing also Figs. 2 and 3, a slot 31 is defined by a space between adjacent ribs 28 which are positioned around the periphery of the capillary feed plate 32 and extend from the lower or bottom surface of the capillary feed plate. Accordingly, a plurality of slots are provided, the specific number of which slots and ribs is not critical so long as a sufficient number are present to adequately supply liquid to the capillary feed passageway. However, the dimensions of the ribs, particularly their thickness, is important in maintaining the proper spacing or separation of the bottom surface of the capillary feed plate from the upper surface 22 of the bottom plate which space forms the capillary feed passageway as previously described.

A plurality of channels 25 are formed and extend through the capillary feed plate to communicate the liquid holding chamber 20 with capillary feed passageway 33 to improve the performance of the apparatus of the invention. As previously explained, without such channels, as the liquid medication in liquid holding chamber is drawn down to a relatively low volume, a small amount of the liquid, for example, up to about two milli ters or more, can remain on the upper surface of the capillary feed plate, particularly when the nebulizer is held in a vertical position. However, with channels 25 present on the upper surface of the capillary feed plate liquid on the plate surface will pass into the channels and be directed to the capillary feed passageway 33. The channels are preferably uniformly spaced apart on the capillary feed plate, and in the embodiment shown in Figs. 2 and 3 extend radially from the spray nozzle 30. Alternatively, the channels may extend in other directions along the capillary feed plate between the peripheral or outer edge of the capillary feed plate and the spray nozzle 30, for example, in zig-zag, crossed, V, W, S or other curved shapes or patterns, any of which or combinations of which may be used to achieve the desired improvement In preferred embodiment illustrated, radial channels 25 extend at least half of the distance from the outer edge of the capillary feed plate to the spray nozzle Preferably, the number of such channels is between 4 and 16, and more preferably is 8 or more. Generally, it is preferred to incorporate a greater number of narrower channels rather than a smaller number of larger or wider channels, the latter which may unduly interrupt the efficiency of the capillary feed performance of the device

Figs. 4 and 5 illustrate examples of alternative channel embodiments within the scope of the invention. In Fig. 4, channels 29 are shown as arc shaped segments of concentric rings on the capillary feed plate 32. In Fig. 5 the channels comprise a series of round holes or ports aligned along radial axes. Such ports need not be circular and may have other desirable shapes and be spaced apart in other patterns or randomly spaced, as may the plurality of channels, so long as they do not interfere with the performance of the capillary feed passageway to adequately and sufficiently direct liquid from the liquid holding chamber to the liquid flow passageway. Combinations of different channel shapes, patterns and spacing may also be used.

The baffling or impingement of the aerosol after it is forced from spray port 19 is not part of the present invention. Any suitable baffle, target or impingement surface design may be used, for example, as disclosed in the aforesaid patents, as well as U.S Patent No 3,762,409.

Claims

WHAT IS CLAIMED IS:

1. A capillary feed nebulizer comprising a liquid holding chamber having a bottom plate, a gas nozzle extending along an axis from the bottom plate, a spray nozzle coaxially mounted relative to the gas nozzle and spaced therefrom to form one or more liquid flow passageways therebetween, a capillary feed plate overlying said bottom plate and forming a capillary feed passageway therebetween, said capillary feed passageway communicating with said one or more liquid flow passageways and said liquid holding chamber, said capillary feed plate having a plurality of channels therethrough communicating between said liquid holding chamber and said capillary feed passageway

2. A nebulizer of claim 1 wherein said channels comprise elongated slits

3 A nebulizer of claim 1 having a sidewall integral with said bottom plate to form said liquid holding chamber and wherein the edge of said capillary feed plate is spaced from said sidewall to from a liquid flow inlet for directing liquid from said liquid holding chamber to said capillary feed passageway.

4. A nebulizer of claim 1 wherein said capillary feed plate is integral with said spray nozzle.

5 A nebulizer of claim 4 wherein at least a portion of said channels extend at least half of the distance from the outer edge of said capillary feed plate to said spray nozzle.

6. A nebulizer of claim 4 wherein the outer edge of said capillary feed plate is circular and said spray nozzle extends from the center of the capillary feed plate and wherein said channels extend radially between said spray nozzle and said outer edge.

7. A nebulizer of claim 1 wherein said gas nozzle is integral with the bottom plate.

8. A nebulizer of claim 3 wherein said bottom plate extends laterally from said gas nozzle to said sidewall.

9 A nebulizer of claim 8 wherein said gas nozzle extends along an axis from the bottom plate and wherein said bottom plate extends at an angle of between about 35° and about 120° from said axis

10 A nebulizer of claim 8 wherein said bottom plate extends at an angle of between about 70° and about 1 10° from the axis of said gas nozzle.

1 1. A nebulizer of claim 8 said bottom plate extends along a plane substantially normal to the axis of said gas nozzle.

12 A nebulizer of claim 3 wherein said capillary feed plate includes a plurality of ribs along or adjacent to the edge thereof, said ribs being spaced apart to form a plurality of slots communicating between said capillary feed passageway and said liquid flow inlet

13. A nebulizer of claim 12 wherein the edge of said capillary feed plate is circular and said liquid flow inlet is annular, and wherein said slots are uniformly spaced along or adjacent to said circular edge of said capillary feed plate.

14. A nebulizer of claim 13 wherein said capillary feed plate comprises a top surface exposed to said liquid holding chamber and a bottom surface exposed to said capillary feed passageway and wherein said ribs project from said bottom surface.

15. A nebulizer of claim 1 wherein said bottom plate and said capillary feed plate are substantially flat.

16. A nebulizer of claim 1 wherein said bottom plate and said capillary feed plate are curved.

17. A nebulizer of claim 1, 3, 5, 6, 7, 8, 9, 10, 1 1, 12, 13, 14, 15 or 16 wherein said bottom plate and said capillary feed plate are substantially parallel.

18. A nebulizer of claim 1 or 5 wherein said channels are uniformly spaced along said capillary feed plate.

19. A nebulizer of claim 2 wherein said plurality of channels is between 4 and 16.

20. A nebulizer of claim 1 wherein said plurality of channels is 8 or more

21. A nebulizer of claim 20 wherein said channels comprise holes, slots or combinations of holes and slots.