Abstract:
The present invention relates generally to a nebulizer, and more particularly but not exclusively to a compact nebulizer that efficiently utilizes medication.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims the benefit of priority of U.S. Provisional Application No. 60/891,892 filed on Feb. 27, 2007, the entire contents of which application are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]    The present invention relates generally to a nebulizer, and more particularly but not exclusively to a compact nebulizer that efficiently utilizes medication. 
       BACKGROUND OF THE INVENTION  
       [0003]    The deposition efficiency in the tracheobronchial (TB) and pulmonary regions is highly dependent on particle size. Particle sizes in the range of about 1 to 5 mm, as well as the size range extending from approximately 0.005 to 0.5 mm, have a relatively high rate of deposition within the aforementioned regions. Various methods have typically been used to generate these therapeutic fine particles, such as air-blast nebulizers (i.e., compressed air, jet, or venturi nebulizer), pressure nebulizers, ultrasonic nebulizers, a vibrating orifice, a spinning disk, condensation devices, and inkjet technology-based nebulizers. However, despite the variety of methods used to generate therapeutic fine particles, problems remain such as wasted medication that is not dispensed and the swallowing of liquid medication by the user. Currently available nebulizers typically have residual (i.e., waste) medication of 50% or more. Thus, it would be in advancing the state of nebulizer art to more efficiently dispense and utilize liquid medication, and to protect the user of the nebulizer from swallowing liquid medication. 
       SUMMARY OF THE INVENTION  
       [0004]    The present invention provides a nebulizer comprising or having a curved surface and a nozzle oriented so that outflow from the nozzle engages the curved surface. The nebulizer incorporates a nebulizer tube, which may comprise a single-piece, that may include a convergent-divergent, air mixing nozzle, as well as an integral feed channel for siphoning medication. The nebulizer tube independently provides a first-level (i.e., relatively coarse) atomization. To obtain the fine particles desired for nebulizers, the output stream from the nebulizer tube is directed towards an impactor having a curved surface at or proximate the impact site. When the flow strikes the impactor, very fine particles are generated. The curvature of the impactor promotes two very desirable effects. First, the portion of the flow that is not atomized into very fine particles will drain down the impactor and return to a medication reservoir disposed under the impactor, creating a “waterfall” recycling effect. Second, the impactor curvature also helps to direct the nebulized medication in a preferred direction, in this case toward the user&#39;s mouth. (The nebulizer of the present invention may be configured to substantially fit within the user&#39;s mouth, and this relatively small size of the nebulizer contributes to minimizing the amount of residual medication.) 
         [0005]    The present invention also reduces the risk to the user associated with the inadvertent swallowing of unacceptably large quantities of liquid medication present in the nebulizer&#39;s reservoir. This could occur if the patient were to tilt his or her head too far back. To substantially reduce this risk, a semi-permeable membrane or other suitable material that is permeable to mist but sufficiently impermeable to liquid may be deployed to allow delivery of the nebulized mist to the user but prevent the flow of bulk liquid medication. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The foregoing summary and the following detailed description of the preferred embodiments of the present invention will be best understood when read in conjunction with the appended drawings, in which: 
           [0007]      FIG. 1  schematically illustrates a perspective view of a first exemplary nebulizer of the present invention; 
           [0008]      FIG. 2  schematically illustrates the nebulizer of  FIG. 1 , but without the semi-permeable membrane in place; 
           [0009]      FIG. 3  schematically illustrates a cross-sectional view of the nebulizer of  FIG. 2  taken along the sectioning line  3 - 3 ; 
           [0010]      FIGS. 4A and 4B  schematically illustrate perspective views of exemplary configurations of the lower housing of a nebulizer; 
           [0011]      FIGS. 5A and 5B  schematically illustrate perspective views of exemplary configurations of the lower housing of a nebulizer of the present invention having a enlarged region for receiving liquid medication; 
           [0012]      FIGS. 6 ,  7 A, and  7 B schematically illustrate perspective views of exemplary configurations of the upper housing of the nebulizer of the present invention; 
           [0013]      FIG. 8  schematically illustrates a cross-sectional view of a nebulizer similar to that depicted in  FIG. 3 , but including the lower housing of  FIG. 4B  and the upper housing of  FIG. 7A ; 
           [0014]      FIG. 9  schematically illustrates the cross-sectional view of the nebulizer of  FIG. 3  with the lower housing removed and with the upper housing rotated to show the internal cavity facing upward; 
           [0015]      FIG. 10  schematically illustrates the perspective view of the nebulizer  FIG. 2  with the lower housing removed and with the upper housing rotated to show the internal cavity facing upward; 
           [0016]      FIGS. 11 and 12  schematically illustrate a perspective and cross-sectional view taken along the sectioning line  12 - 12 , respectively, of a nebulizer tube of the present invention; 
           [0017]      FIG. 13  schematically illustrates a perspective view of a second exemplary nebulizer of the present invention; 
           [0018]      FIG. 14  schematically illustrates a cross-sectional view of the nebulizer of  FIG. 13  taken along the sectioning line  14 - 14 ; 
           [0019]      FIG. 15  schematically illustrates a perspective view of the lower housing of the nebulizer of  FIG. 13 ; 
           [0020]      FIG. 16  schematically illustrates a perspective view of the lower housing of the nebulizer of  FIG. 13  with the nebulizer tube in place; 
           [0021]      FIG. 17  schematically illustrates the nebulizer tube of  FIG. 13  having key for insertion in the upper housing; 
           [0022]      FIG. 18  schematically illustrates a perspective view of the upper housing of the nebulizer of  FIG. 13  having a keyway for receiving the key of the nebulizer tube; 
           [0023]      FIG. 19  schematically illustrates a perspective view of the upper housing of the nebulizer of  FIG. 13  with the nebulizer tube in place with the key of the nebulizer tube disposed in the keyway of the upper housing; 
           [0024]      FIGS. 20A and 20B  schematically illustrate perspective views of a liquid fill cap; and 
           [0025]      FIGS. 21A and 21B  schematically illustrate alternative airfoil shapes for the impactor. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    Referring now to the figures, wherein like elements are numbered alike throughout,  FIGS. 1 and 2  illustrate an external view of a first configuration of a nebulizer  100  of the present invention. The nebulizer  100  comprises a nebulizer tube  1  disposed within a housing  40  for receiving compressed air and an exit port  10  for delivering a nebulized mist to a user. The housing  40  may comprise an upper housing  2  and a lower housing  3 , which may be registered to one another by cooperation between holes  12  of the lower housing  3  and alignment posts  16  of the upper housing  2 ,  FIGS. 4A ,  6 . The upper housing  2  may include a fill port  30  for introducing a liquid medication into the housing  40 . The fill port  30  may be shaped to readily accept the shape of standard medicine containers, which will facilitate filling of the nebulizer  100  with the correct amount of medication and reduce the possibility of spillage and waste. The fill port  30  may remain open and may also serve as an exit for nebulized liquid, or the fill port  30  may optionally include a separate funnel or duckbill-shaped cap  31  for insertion into the upper housing  2  to direct the liquid medication into the housing  40 ,  FIGS. 1 ,  3 ,  20 A,  20 B. Alternatively, the fill port cap  230  may be provided as an integral portion of the upper housing  202 ,  FIGS. 13 ,  14 . The cap  31 ,  230  may be configured so that it deflects to permit liquid to be poured into the nebulizer when a small force applied. For example, the cap  31 ,  230  may deflect when a syringe or tubular exit of a plastic ampule is inserted for delivering liquid and may close again after the syringe/ampule is removed. 
         [0027]    To receive liquid medication introduced through the fill port  30 , the lower housing  3  includes a reservoir  7  which may include a cylindrical sidewall  33  for containing the liquid medication within a localized region within the lower housing  3 . The reservoir  7  may be dimensioned to hold at least 3 ml of liquid medication, for example. In addition, to further contain the location of the liquid medication, the reservoir  7  may include a hemispherical or other suitably shaped depression  34  into which the liquid medication may pool. Maintaining the liquid medication in a specified location assists in making the medication available to the nebulizer tube  1 , and thus aids in efficient use of the medication. 
         [0028]    The reservoir  7  may include shapes other than cylindrical. For example, the reservoir  7 ″ may have a generally rectangular shape being bounded at the inlet and outlet end of the lower housing  3 ″ by front and rear reservoir walls  13   a,    13   b,    FIG. 5A . The reservoir walls  13   a,    13   b  may be straight, curved  13   a ′, or assume any other suitable shape,  FIGS. 5B ,  16 . In addition, in the event that liquid medication overflows the wall  33 ′ of the reservoir  7 ′, an overflow wall  13  may optionally be provided at the exit port  10  to help deter introduction of liquid medication into the user&#39;s mouth,  FIG. 4B . Furthermore, one or more semi-permeable membranes  4  may be provided at the exit port  10  of the nebulizer  100  to permit vapor flow while acting as an effective liquid barrier, thus creating a safety feature that prevents a user from swallowing liquid medication contained in the nebulizer  100 . In one configuration the semi-permeable membranes  4  may be used instead of the front reservoir wall  13   a.  Alternatively, or additionally, an absorbent material, such as a sponge, may be incorporated into the nebulizer  100 , for example between the reservoir  7 ′ and overflow wall  13 , to deter the outflow of liquid medication into the exit port  10 . For instance, in the event that the nebulizer is tilted beyond some critical angle during use, the membrane  4  and/or absorbent material will block the flow of medication into the user&#39;s mouth. 
         [0029]    The nebulizer tube  1  includes a feed channel  6  having an inlet end  42  disposed in fluid communication with the reservoir  7  to receive liquid medication disposed within the lower housing  3 ,  FIGS. 3 ,  12 . The feed channel  6  communicates with an air channel  5  of the nebulizer tube  1  to deliver the liquid medication to the air channel  5  to be nebulized. The air channel  5  includes an inlet end  41  for connection to a source of compressed air and a throat  43  where the feed channel  6  connects to the air channel  5 . The air channel  5  may be provided in the form of a convergent channel  5  that has a cross-sectional dimension that decreases from the inlet end  41  to the throat  43  where the cross-sectional dimension may be a minimum. The nebulizer tube  1  also includes a nozzle  8  disposed in fluid communication with the throat  43  of the air channel  5 . The nozzle  8  include a channel cross-sectional dimension that increases away from the throat  43  towards the outlet end  44  of the nebulizer tube  1 . 
         [0030]    The inlet end  41  of the nebulizer tube  1  may include a barb  18  to assist in securing attachment of a compressed air hose to the inlet end  41  of the nebulizer tube  1 ,  FIGS. 11 ,  12 . A flange  19  may also be included to provide a positive stop for the air hose during initial installation. During operation, compressed air enters the convergent channel  5  of the nebulizer tube  1 . The air accelerates until it reaches the throat  43  of the convergent channel  5 . By virtue of the Bernoulli effect, as the flow velocity increases, its static pressure will decrease. As a result, the pressure at the throat  43  of the convergent channel  5  will be below that of the local atmospheric pressure. Since the static pressure of the liquid is higher than the pressure at the throat  43  of the nebulizer tube  1 , liquid is siphoned upward into the feed channel  6  as a result of a venturi effect. Subsequent to siphoning, the liquid/air mixture is rapidly expanded in the divergent section of the nozzle  8 . This rapid expansion encourages turbulent mixing and creates an effective first-level of atomization. 
         [0031]    The nozzle  8  is oriented so that the output flow from the nozzle  8  strikes a curved impactor  9 , which may be provided as part of the upper housing  2 . This energetic collision generates the very fine, therapeutic particles required of nebulizers. It has been determined that a sufficiently small spacing is required between the nozzle  8  and impactor for fine mist generation. A suitable nozzle to impactor spacing is 10 or 30 thousandths of an inch. The location of the nozzle  8  relative to the curved impactor  9  may be specified by an alignment boss  21  provided on the nebulizer tube  1  that mates with a complementary positioning feature  11  of the lower housing  3  to locate the nebulizer tube  1  within the housing  40 . In addition, the nebulizer tube mates with an nozzle capture feature  15  of the upper housing  2  to stabilize the tube  1  within the nebulizer  100 ,  FIGS. 8-10 . Additionally, or alternatively, registration of the nebulizer tube  1  to the impactor  9  may be provided by direct or indirect physical cooperation between the nebulizer tube  1  and impactor  9 . For example, referring to  FIGS. 16-19  (wherein structures similar to those illustrated in  FIGS. 1-12  are similarly numbered with a “200”-series reference numeral), the nebulizer tube  201  may include a registration feature, such as a key  251 , for mating with a complementary structure, such as keyway  252 , on the nebulizer  209 . Engagement between the key  251  and the keyway  252  establishes the relative position between the nozzle  208  and the impactor  209 . 
         [0032]    The impactor  9 ,  209  may have a generally cylindrical shape, such as a substantially full cylinder,  FIG. 6 , or a partial cylindrical impactor  17 ,  FIG. 7A . Such impactor shapes will generate a fine mist and will also facilitate the flow of mist toward the user&#39;s mouth. Other curved surfaces may be substituted for the cylindrical impactors  9 ,  209  such as elliptical, or other suitable shape, e.g., an airfoil  60 ,  FIG. 21A . In addition, the curved impactor may have a cross-sectional shape which includes a flat region  62  as well as a curved region  63 , such as the airfoil  64  illustrated in  FIG. 21B , for example. The airfoil impactor  60 ,  64  is oriented within the housing  40 ,  240  so that the tapered portion of the airfoil points in the downstream direction towards the exit port  10 ,  210  of the nebulizer  100 ,  200 . Such an orientation of the airfoil impactor  60 ,  64  would reduce turbulence and backpressure of the air and mist as it moves out the exit port  10 ,  210  of the nebulizer  100 ,  200 . 
         [0033]    In addition to creating a fine mist, the curved impactor  9  also provides at least two other desirable functions: (I) it helps direct the nebulized mist towards the user&#39;s mouth, and (ii) it facilitates a waterfall-like recycling effect. The waterfall effect arises because part of the mixture exiting the nebulizer tube  1  will strike the impactor  9  and simply drain back down into the region containing the pool of liquid, i.e., reservoir  7 . In this regard, the impactor  9  may be positioned above the reservoir  7 . Of course, a significant portion of the air/liquid mixture will exit via port  10  of the nebulizer as a mist directed toward the user&#39;s mouth. An air baffle  20  may be provided on the nebulizer tube  1  proximate the feed channel inlet end  42 , so that the high-velocity mixture striking the impactor  9  does not blow liquid away from the feed channel inlet  42  which could lead to a feed channel starvation condition. In addition, inclusion of the air baffle  20  can deter unwanted formation of large airborne droplets that might result from the surface of the liquid being agitated. 
         [0034]    Additionally, the impactor  9 ,  209  can be shaped to create a scavenging flow within the nebulizer  100 ,  200 . The scavenging flow would be directed throughout the housing interior and would help prevent the accumulation of medication on the internal walls of the nebulizer  100 ,  200 . In addition, curtain walls  61 ,  261  are provided in the upper housing  2 ,  202  to redirect any accumulation of liquid on the upper surface of the upper housing  2 ,  202  downward into the reservoir  7 ,  207 . The presence of curtain walls  61 ,  261  can avoid the situation of liquid running down the interior sidewall of the upper housing  2 , 202  to encounter and potentially leak out through the seam between the upper housing  2 ,  202  and the lower housing  3 ,  203 . The curtain walls  261  are also positioned sufficiently close to the impactor  209  to permit fine particles to travel around the impactor  209  to the exit port  210  and to cause larger particles to strike the curtain walls  261  and then drip down into the reservoir  207 . Additionally, a filter-type material may be positioned in the nebulizer  100 ,  200  to give a preferential flow direction for the nebulized mist toward the user&#39;s mouth without creating an excessive flow resistance to inhalation. Furthermore, the housing  40 ,  240  and/or other components of the nebulizer  100 ,  200  may be fabricated from materials that possess surface tension properties characteristic of wetting materials to create a sheeting action that will facilitate the flow of recycled materials to the reservoir  7 ,  207 . 
         [0035]    These and other advantages of the present invention will be apparent to those skilled in the art from the foregoing specification. Accordingly, it will be recognized by those skilled in the art that changes or modifications may be made to the above-described embodiments without departing from the broad inventive concepts of the invention. It should therefore be understood that this invention is not limited to the particular embodiments described herein, but is intended to include all changes and modifications that are within the scope and spirit of the invention as set forth in the claims.