Nebulizer apparatus and method

A nebulizer for efficiently and reliably delivering aerosolized fluid to an inhaling patient is disclosed. The nebulizer includes a fixed diverter and a movable fluid orifice or fluid pathway connected with an actuator for responding to an inhalation or a manual actuation and beginning the nebulization process. Also provided is a method of providing nebulization including the steps of moving a fluid orifice or fluid pathway connected to an actuator so that the fluid orifice or fluid pathway reaches a nebulizing position during inhalation.

 

1. A nebulizer comprising:

a housing having an ambient air inlet and a chamber for holding an aerosol;

an air outlet communicating with the chamber for permitting the aerosol to be withdrawn from the chamber;

a pressurized gas inlet adjacent a fluid orifice, the pressurized gas inlet in communication with the chamber;

a diverter positioned in the chamber in a fixed position relative to the pressurized gas inlet;

an actuator piston connected with a pressurized gas inlet cover defining a portion of the fluid orifice and positioned in the housing, the actuator piston responsive to an initial period of inhalation through the air outlet to adjust the fluid orifice to a nebulizing position

wherein at least one portion of the fluid orifice is adjustable, in response to a patient's breathing, between the nebulizing position and a non-nebulizing position.

2. The apparatus of claim 1 further comprising a relief piston located in the housing, the relief piston movable separately from the actuator piston and responsive to additional negative pressure in the chamber, after an initial period of inhalation, to allow increased air flow from the air inlet into the chamber, whereby the effort necessary for a patient inhaling through the air outlet is reduced.

3. The apparatus of claim 1, wherein the fluid orifice comprises an opening defined by an outer diameter of the pressurized gas inlet and an inner diameter of an end of the pressurized gas inlet cover.

4. The apparatus claim 3, wherein the pressurized gas inlet comprises a cone-shaped nozzle and the pressurized gas inlet cover comprises a cone-shaped sleeve coaxially positioned around the cone-shaped nozzle.

5. The apparatus of claim 1, wherein the at least one portion of the fluid orifice comprises an entire fluid orifice.

6. The apparatus of claim 1, wherein the fluid orifice is in communication with a fluid reservoir positioned inside the nebulizer.

7. A breath actuated nebulizer for providing an aerosol to an inhaling patient, the nebulizer comprising:

a housing having an air inlet and a chamber for holding the aerosol;

an air outlet communicating with the chamber for permitting the aerosol to be withdrawn from the chamber;

a pressurized gas inlet located in the chamber;

a fluid orifice located in the chamber adjacent the pressurized gas inlet, the fluid orifice in communication with a fluid pathway, wherein the fluid orifice comprises an opening defined by an outer diameter of the pressurized gas inlet and an inner diameter of an end of a pressurized gas inlet cover;

an actuator piston movably positioned adjacent the air inlet and connected with the at least a portion of the pressurized gas inlet cover, wherein the actuator piston and the at least a portion of the pressurized gas inlet cover are movable in response to inhalation at the air outlet; and

wherein at least a portion of the fluid pathway is adjustable in response to a patient's breathing between a nebulizing position, wherein a flow of fluid from a fluid reservoir to the fluid orifice is uninterrupted, and a non-nebulizing position wherein the flow of fluid from the fluid reservoir to the fluid orifice is interrupted.

8. The apparatus of claim 7, wherein the air inlet is configured to receive a supply of air from an air supply system.

9. The apparatus of claim 7, wherein the air inlet is configured to receive ambient air from outside the chamber.

10. The apparatus of claim 7, wherein the fluid pathway comprises at least one channel defined by a recessed longitudinal groove in at least one of the outer diameter of the pressurized gas inlet and the inner diameter of the pressurized gas inlet cover.

11. The apparatus of claim 7, wherein the pressurized gas inlet comprises a nozzle and the pressurized gas inlet cover comprises a nozzle cover coaxially positioned around the nozzle, wherein at least a portion of the nozzle cover is movable with respect to the nozzle.

12. The apparatus of claim 7 further comprising a relief piston positioned adjacent the actuator piston and independently movable with respect to the actuator piston in response to a continued inhalation to uncover additional openings in the nebulizer and thereby reduce inhalation effort.

13. The apparatus of claim 7 further comprising a diverter positioned in the chamber to divert a flow of gas from the pressurized gas inlet.

14. The apparatus of claim 13, wherein the diverter is stationary.

15. A method of providing a patient with an aerosol flow of fluid comprising:

providing a nebulizer having an air inlet for receiving air and an outlet for delivering the aerosol to the patient, a chamber in communication with the outlet, a diverter fixedly mounted in the chamber, and a movable fluid orifice responsive to movement of an actuator piston;

inhaling air from the chamber through the outlet;

moving the actuator piston so that the fluid orifice moves from an initial position to a predetermined distance from a pressurized gas inlet in the chamber;

creating a negative pressure over a fluid orifice by injecting pressurized gas into the chamber and deflecting the gas against the diverter;

drawing medication through the fluid orifice with the negative pressure; and

wherein the fluid orifice is an opening defined by an outer circumference of the pressurized gas inlet and an inner circumference of an end of a coaxially positioned pressurized gas inlet cover connected with the actuator piston, and wherein moving the actuator piston comprises moving the pressurized gas inlet cover relative to the pressurized gas inlet such that the fluid orifice moves to the predetermined position.

16. The method of claim 15, wherein the nebulizer further comprises a relief piston mounted in the nebulizer and independently movable with respect to the actuator piston, and wherein the method further comprises moving the relief piston independently of the actuator piston to permit greater air flow through the chamber after the fluid orifice moves to the predetermined distance from the pressurized gas inlet.

17. The method of claim 15, wherein moving the actuator piston comprises moving the actuator piston in response to the breathing of the patient.

FIELD OF THE INVENTION

The present invention relates to a method and apparatus for generating an aerosol for delivery to a patient. More particularly, the present invention relates to a nebulizer configured to nebulize a fluid into an aerosol in coordination with a patient's breathing.

BACKGROUND

Medical nebulizers that nebulize a fluid into an aerosol for inhalation by a patient are well-known devices commonly used for the treatment of certain conditions and diseases. Nebulizers have applications for conscious, spontaneously-breathing patients and for controlled, ventilated patients.

In some nebulizers, a gas and a fluid are mixed together and directed against a baffle or diverter. In some other nebulizers, interaction of the gas and fluid is enhanced through impacting the gas and fluid against a diverter. The term diverter, as used in this specification, includes any baffle or impinger. As a result of either nebulization process described above, the fluid is transformed into an aerosol, that is, the fluid is caused to form small particles that are suspended in the air and that have a particle size in a range suitable for delivery to a targeted area of a patient's respiratory tract. One way to mix the gas and fluid together in a nebulizer is to pass a quickly moving gas over a fluid orifice tip of a tube. The negative pressure created by the flow of pressurized gas is a factor that contributes to drawing fluid out of the fluid orifice into the stream of gas and nebulizing it.

Important considerations in the design of a nebulizer are the timing and dosage regulation of the aerosolized fluid. In some nebulizer designs, a continuous stream of pressurized gas entrains the fluid against the diverter to constantly generate an aerosol until the fluid in a reservoir is depleted. Continuous nebulization may result in a waste of aerosol during a patient's exhalation or during a delay between inhalation and exhalation. The amount of wasted aerosol may be difficult to quantify and some of the aerosol may be lost to condensation on the nebulizer or mouthpiece during periods of non-inhalation. Nebulizers implementing a timed or non-continuous nebulization may adversely affect particle size and density as the nebulization is turned on and off.

Effective and economical nebulizer therapy includes the ability to quickly generate a large amount of aerosol within a predetermined particle size range. An effective nebulizer preferably provides these features synchronously with the inhalation of the patient. In order to actuate a mechanical nebulizer, a patient's inhalation effort must overcome certain variables. Depending on the structural configuration of the nebulizer, these variables may include one or more of the following: the volumetric flow rate of the flowing gas; air leaks in the device; the force exerted by the flowing gas on a moveable diverter; and the friction between moveable parts. The greater the flow rate, air leaks and friction, the greater the inhalation effort required in order to actuate the device. It is desirable that a nebulizer have adequate sensitivity to quickly respond to an inhalation while not adversely restricting the patient's inhalation.

BRIEF SUMMARY

In order to address the deficiencies in the prior art and provide improved performance, a nebulizer and method are provided. According to a first aspect of the invention, a nebulizer is provided with a housing having an ambient air inlet and a chamber for holding an aerosol. An air outlet communicates with the chamber for permitting the aerosol to be withdrawn from the chamber. A fluid outlet and a pressurized gas outlet are in communication with the chamber where the pressurized gas outlet is located adjacent to the fluid outlet. In one preferred embodiment, the fluid outlet is preferably positioned at the opposite end of a nozzle cover from a fluid inlet, wherein the fluid inlet is capable of fluid communication with a reservoir. A diverter is positioned in the chamber in a fixed position relative to the pressurized gas orifice.

At least one portion of the fluid orifice is adjustable between a nebulizing position and a non-nebulizing position. As used in this specification, the term "fluid orifice" means either the fluid inlet or the fluid outlet and may be used interchangeably with these terms. The nebulizer may have an actuator piston connected with at least a portion of a nozzle cover to move all or part of the fluid orifice, or all or part of the fluid pathway between the reservoir of fluid and the fluid orifice. Additionally, a relief piston independently movable with respect to the actuator piston may be used to alleviate inhalation effort after an initial period of inhalation. In one embodiment, the fluid orifice is movable in response to a patient's breathing. In another embodiment, the fluid orifice is movable by moving a mechanical actuator by hand. In yet further embodiments, the diverter may be movable relative to the nebulizer housing, but fixedly positioned relative to either the pressurized gas orifice or fluid orifice.

According to another aspect of the invention, a method of providing a nebulized fluid to a patient includes providing a nebulizer having a diverter fixedly positioned with respect to a pressurized gas outlet in a chamber, a fluid reservoir in communication with the chamber, and an adjustable fluid pathway movably positioned to communicate fluid in the fluid reservoir with a fluid orifice in response to inhalation by the patient. Upon inhalation through an air outlet connected to the chamber, a position of the fluid pathway is adjusted with the force of the inhalation such that the fluid in the chamber is nebulized.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is an elevational side view of a nebulizer according to one embodiment of the present invention.

FIG. 2 is an exploded top perspective view of the nebulizer of FIG. 1.

FIG. 3 is an exploded bottom perspective view of the nebulizer of FIG. 1.

FIG. 4 is a bottom perspective view of a nozzle cover suitable for use in the nebulizer of FIG. 1.

FIG. 5 is a cross-sectional view of the nozzle cover of FIG. 4.

FIG. 6 is a cross-sectional view of the nebulizer of FIGS. 1-3 in a non-actuated position.

FIG. 7 is a cross-sectional view of the nebulizer of FIG. 6 in a fully actuated position.

FIG. 8 is a cross-sectional view of the nebulizer of FIG. 1 illustrating air flow in a fully actuated position.

FIG. 9 is a cross-sectional view of an alternative embodiment of a diverter arrangement suitable for use with the nebulizer of FIG. 1.

FIG. 10 is a cross-sectional view of a second alternative embodiment of a diverter arrangement suitable for use with the nebulizer of FIG. 1.

FIG. 11 is a cross-sectional view of a third alternative embodiment of a diverter arrangement suitable for use with the nebulizer of FIG. 1.

FIG. 12 is a partial cross-sectional view of an alternative embodiment of the nebulizer of FIGS. 1-8 in an actuated position.

FIG. 13 is a partial cross-sectional view of the nebulizer of FIG. 12 in a non-actuated position.

FIG. 14 is an exploded side elevational view of a second alternative embodiment of the nebulizer of FIGS. 1-8.

FIG. 15 is a partial cross-sectional view of the nebulizer of FIG. 14 in an actuated position.

FIG. 16 is a partial cross-sectional view of the nebulizer of FIGS. 14-15 in a non-actuated position.

FIG. 17 is a cross-sectional view of a third alternative embodiment of the nebulizer of FIGS. 1-8 in a non-actuated position.

FIG. 18 is a partial cross-sectional view of the nebulizer of FIG. 17 in an actuated position.

FIG. 19 is an alternative nozzle cover and vane assembly, in a non-actuated position, for use in the nebulizer of FIGS. 17-18.

FIG. 20 is an alternative nozzle cover and vane assembly, in an actuated position, for use in the nebulizer of FIGS. 17-18.

FIG. 21 is an exploded view of a fourth alternative embodiment of the nebulizer of FIGS. 1-8.

FIG. 22 is a cross-sectional view of the nebulizer of FIG. 21 in a non-actuated position.

FIG. 23 is a cross-sectional view of the nebulizer of FIG. 21 in an actuated position.

FIG. 24 is a sectional view of the nebulizer of FIGS. 21-23.

FIG. 25 is a lid and relief piston assembly suitable for use in the nebulizer of FIG. 21.

FIG. 26 is an alternative lid and relief piston assembly for use in the nebulizer of FIG. 21.

FIG. 27 is a cross-sectional view of a nebulizer illustrating a locking lever.

FIG. 28 is a sectional view of the nozzle and nozzle cover of FIG. 23.

FIG. 29 is a sectional view of the nozzle and nozzle cover of FIG. 22.

FIG. 30 is a cross-sectional view of an alternative embodiment of the nebulizer of FIGS. 21-24 with a gas nozzle and nozzle cover arranged in internal mixing configuration.

FIG. 31 is a sectional view of the gas nozzle and nozzle cover in the nebulizer of FIG. 30 in an actuated position.

FIG. 32 is a sectional view of the gas nozzle and nozzle cover in the nebulizer of FIG. 30 in a non-actuated position.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

A preferred embodiment of a nebulizer 10 for nebulizing a fluid is shown in FIGS. 1-3. As used in this specification, the term "fluid" includes, without limitation, a fluid comprising a medicine, whether in the form of an emulsion, suspension or solution, that can be nebulized into an aerosol. The embodiment of FIGS. 1-3 comprises a lid 11 attached to a housing 13 having a top portion 12, a cylindrical middle portion 14, and a bottom portion 16. An air outlet 18 extends from the cylindrical middle portion 14 of the housing 13. The air outlet 18 communicates with air in the chamber 20, defined by the inside of the cylindrical middle portion 14 of the housing, and is suited to receive a mouthpiece. In a preferred embodiment, the component parts of the housing may be formed of separate, multiple pieces of material that are connected together by welding, adhesives, threading, connector tabs. In an alternative embodiment the housing may be constructed of a single piece of material formed by an injection molding process. The housing may be constructed from a plastic material, such as polypropylene, polycarbonate or a polycarbonate blend, or a metal material. Any number of types of plastic or metal may be used to construct these parts of the nebulizer.

Referring to FIGS. 1-7, a pressurized gas inlet 22 extends into the chamber 20 through the bottom portion 16 of the housing. The opening 24 of the pressurized gas inlet 22 is designed to connect with a standard vinyl gas hose. Inside the chamber 20, the pressurized gas inlet 22 forms a nozzle 26 that tapers down to a pressurized gas orifice 28 having a predetermined diameter. In one preferred embodiment, the gas inlet 22 is coaxial with the cylindrical middle portion 14 and extends through the bottom wall 30 of the chamber 20.

A nozzle cover 32 is slideably mounted over the nozzle 26. As shown in FIGS. 4-5, the nozzle cover 32 is preferably a tapered tubular member having openings at either end. The nozzle cover 32 slides over the nozzle 26 of the pressurized gas inlet 22 to form at least one passageway 34 from an opening located near the bottom of the nozzle cover 32 to the top of the nozzle cover. In alternative embodiments, the passageway may be formed by a spacing between the nozzle and nozzle cover, a groove 34 in the inner circumference of the nozzle cover, a groove in the outside of the nozzle, or a combination of grooves on the outside of the nozzle and inside of the nozzle cover. A fluid outlet is positioned adjacent the pressurized gas outlet 28. In one preferred embodiment, the fluid outlet 36 is an annular orifice defined by a gap between the inner diameter of the tip of the nozzle cover and the outer diameter of the tip of the nozzle. The tip of the nozzle cover 32 may include one or more stop pins 41 to limit the upward travel of the nozzle cover 32. Although a single annular orifice is shown, embodiments where the fluid outlet has other shapes, or comprises more than one discrete orifice positioned adjacent the pressurized gas orifice, are also contemplated. A fluid inlet 35 is preferably positioned at the opposite end of the nozzle cover 32. As shown in FIGS. 6-8, the fluid inlet is also an annular orifice and is defined by a gap between the inner diameter of the bottom of the nozzle cover 32 and the outer diameter of the base of the nozzle 26.

An embodiment is also contemplated with fluid pathways that are completely enclosed within the thickness of the nozzle cover such as one or more tunnels bored from, or molded in, the bottom of the nozzle cover extend some or all of the distance up to the opening at the top of the nozzle cover. Further, an alternative embodiment may consist of an array of one or more discrete tubes connected in a ring around the pressurized gas outlet 28, where each of the tubes provides a passageway from the fluid reservoir 80 to a respective point adjacent the pressurized gas outlet 28.

In the embodiment of FIGS. 1-8, the entire nozzle cover 32 is attached to, or integrally molded with, an actuator piston 38. In one embodiment, the nozzle cover includes one or more integrally formed arms 40 that connect to the bottom portion 42 of the circumferential flange 44 of the actuator piston 38. Any number of arms 40 may be utilized.

A diverter 46 is preferably attached to, or integrally molded with, the inside of the nebulizer 10. As shown in FIG. 3, a support beam 48 connects the diverter 46 to an inner cylindrical flange 60 in the middle portion 14 of the nebulizer. Preferably, the diverter 46 has a flat surface having a predetermined area and is positioned at a fixed distance h₁ from the gas orifice 28. In one preferred embodiment, h₁ is approximately 0.75 millimeters (mm) and the width of the diverter is approximately 4.5 mm. The surface is also preferably aligned parallel to the surface of the tip of the nozzle 26 and perpendicular to the flow of pressurized gas through the pressurized gas orifice 28.

Any of a number of configurations for fixing the position of the diverter with respect to the pressurized gas orifice are contemplated. For example, the cylindrical flange 160 may extend further into the chamber 120 so that the diverter 146 and support arm 148 are attached or molded further from the bottom of the cylindrical flange 160 as shown in the embodiment illustrated in FIG. 9. In FIG. 10, an embodiment is shown where the diverter 246 is attached to a support 248 directly connected to the wall of the middle portion of the housing. A shorter cylindrical flange 260 provides clearance for the support 248. Alternatively, as shown in FIG. 11, the diverter 346 may be attached or molded to the lid 311 of the nebulizer via an extension arm 348. In other alternative embodiments, the diverter may be movable with respect to the pressurized gas orifice or may be movable with the pressurized gas orifice such that the pressurized gas orifice and diverter move together independently of the fluid orifice. Another suitable diverter configuration is disclosed in U.S. Pat. No. 6,044,841, the entire disclosure of which is incorporated herein by reference.

Referring again to FIGS. 1-8, the upper portion 12 of the housing 13 forms a cylindrical extension with an open proximal end 52 and a partially closed distal end 54. The distal end 54 has an annular ledge 50 surrounding an opening 58 into the chamber 20. The annular ledge 50 defines at least one air inlet opening 56 and preferably eight air inlet openings distributed along its circumference. Each air inlet opening 56 is located toward the outer periphery of the distal end 54 of the upper portion 12 such that air outside of the nebulizer is primarily directed against an actuator piston 38 covering the air inlet opening 56 during the patient's initial inhalation. Preferably, the nebulizer is configured such that a gap exists between the air inlet opening and the actuator piston when the nebulizer is in a non-actuated state.

The opening 58 at the distal end 54 connects with a chimney, or cylindrical flange 60, extending down into the upper portion of the chamber 20. The cylindrical flange 60 is preferably of a diameter suited to slideably receive the cylindrical extension 62 of the actuator piston 38 that extends downward into the chamber 20. The cylindrical extension 62 is positioned substantially coaxially within the cylindrical flange 60 and acts as a vertical guide for the actuator piston 38. The open proximal end 52 of the upper portion 12 of the housing 13 has a diameter suited to receive the lid 11. The lid 11 may be threaded, snap-fit, friction-fit, molded or welded to the upper portion 12 of the housing 13. The middle portion 14 of the housing 13 is preferably manufactured of a clear plastic so that a caregiver can see the actuator piston and determine if the nebulizer is actuated.

The interior of the upper portion 12 is suited to slideably receive the actuator piston 38 and a relief piston 62, and to receive a biasing means 64 such as a plastic or metal spring. The actuator piston 38, as shown in FIGS. 2-3 and 6-8, includes an outer annular rib 66 with an outer diameter slightly less than the inner diameter of the upper portion 12 of the housing 13 to allow the actuator piston 38 to slide up and down within the upper portion 12. A center hole 68 is bounded by the cylindrical extension 62 that extends both down into the chamber 20 through the opening 58 and, in the opposite direction, a short distance into the upper portion 12. At least one air inlet 72 is located in the actuator piston 38adjacent to the center hole 68 that allows entrained air received from air inlets 56 in the housing to travel through the actuator piston and against the underside of the relief piston 62. As described in more detail below, the negative pressure created above the relief piston 62 during inhalation preferably creates a force suff