GB2152819A - Improved nebuliser - Google Patents

Abstract

A nebuliser for administering bronchodilators, etc., comprises a horizontal cylindrical casing (50) containing active solution (70). Air or gas is supplied through an inlet (56) to a venturi (54) such that solution is drawn up a capillary channel (68) to be entrained in the air stream. From this main chamber the flow enters a subsidiary chamber having peripheral apertures (80). Air is drawn into the subsidiary chamber to dilute and entrain the aerosol flow from the main chamber. The proximity of the aerosol chamber to the patient's mouth means that dead space is kept to a minimum. The supply of solution (70) can be continuously maintained through an inlet (90), to permit continuous nebulisation. The unit comprises a mouthpiece (96) and support (98) resting on the patient's chin such that the unit can be continuously supported on a patient's face. <IMAGE>

Description

SPECIFICATION Improved nebuliser This invention relates to nebulisers.

Patients with bronchial obstructions such as asthma or bronchitis are commonly given broncial ative drugs, in particular bronchodilators, by a nebuliser. Nebulisers may also be used for the administration of antibiotics and mucolytics.

The nebuliser is a device which is capable of converting a solution of active preparation into an aerosol. The nebuliser utilises the venturi effect produced by a Bernoulli nozzle. When air or oxygen is forced through a fine nozzle it forms an area of negative pressure where the high speed jet of gas emerges, and if one end of a tube is placed in this region with the other end in a pool of liquid, liquid will be drawn up, mixed with the high speed jet, and blown out as a cloud of particles.

Figure 1 shows a conventional nebuliser unit which includes a housing 10 in which the solution 12 containing the active drug can be placed in the conical lower portion thereof. The top of the housing is provided with a cover 14 which is provided with an aerosol output 16 and a gas inlet 18. The gas inlet tube terminates in the venturi nozzle 20 and below that is a small chamber 22 defining a region of negative pressure. The chamber 22 has an outlet 24 and in the path of air from the outlet 24 is arranged a baffle 26. Any unduly large droplets will coalesce on the baffle and be returned to the solution 12.

A pipe 28 rests in the solution 12 and opens into the chamber 22 so that solution is drawn into the chamber to form the aerosol.

In use, a mouth piece is connected to the aerosol output 16to enable the vertical flow from the nebuliser to be drawn horizontally into the patient's mouth. Alternatively, a face mask is provided which is placed over the whole of the mouth and nose region of the patient.

Figure 2 illustrates a second known nebuliser.

This is designed to be used horizontally and consists of a horizontal generally cylindrical casing 30. Air or oxygen is introduced through a tube section 32 in the rear face of the casing which terminates in a venturi 34. A low pressure chamber 36 is formed by a shaped plate 38 which carries an aerosol outlet 40 opposed to the venturi 34. The plate 36 extends around the sides of the end of the inlet tube 32 to an annular disc portion 42 closely spaced from the back plate of the housing 30 to provide a capillary gap 44 therebetween.

Solution 46 in the bottom of the nebuliser as shown is drawn up the capillary channel 44 by the negative pressure in chamber 36 so that an aerosol emerges from the opening 40.

On the front face of the casing is positioned a generally tubular section 48 which has a baffle 50 mounted on its rear end. The aerosol within the casing 30 can be drawn into the tube 48 as shown by the arrows A and thence to the patient's mouth.

Again a separate mouth piece or face mask is employed.

For various reasons the known nebulisers do not provide an optimum even flow of aerosol to the patient. It is important when the patient breathes in that the aerosol should reach the patient's bronchial tract as quickly as possible and not just in the final stages of taking breath. The inventor has appreciated that the known nebuliser units have a relatively large therapeutic dead space which means that the aerosol takes too long to reach the active region to provide optimum efficaciousness.

Accordingly, in a first aspect this invention provides a nebuliser unit comprising a casing defining a main chamber for containing active solution and having an aerosol outlet, and a subsidiary chamber arranged around the aerosol outlet of the main chamber, the unit including an aerosol chamber into which a venturi opens and into which solution in the main chamber can be drawn to form an aerosol, and the subsidiary chamber having inlet means whereby air can be drawn into the subsidiary chamber for dilution and entraining of the aerosol flow from the main chamber.

The inventor has also appreciated that the use of a nebuliser inherently is wasteful in drugs and is not as effective as it should be, because the patient receives intermittent doses spaced by a period of time. In serious cases much greater beneficial effect could be achieved at less relative intake of drug by providing continuous nebulisation. None of the existing nebuliser units are able to function in this way.

In a second aspect the invention, therefore, provides a nebuliser unit comprising a casing defining a main chamber for containing active solution and having an aerosol outlet, and an aerosol chamber into which a venturi opens and into which solution in the main chamber can be drawn to form an aerosol, the main chamber further including a solution inlet whereby a supply solution can be maintained continously in the main chamber in use of the unit, and the casing having means including a mouthpiece whereby the unit can be continuously supported on a patient's face.

An example of the invention will now be described with reference to the remaining Figures of the drawings in which: Figure 3 is a side sectional view through a first nebuliser unit embodying the invention designed for intermittent use, and Figure 4 is a similar view of a modified nebuliser unit for continuous use.

Referring first to figure 3, the nebuliser shown includes a generally cylindrical casing 50 having a rear face 52. The venturi 54 is formed by a hole in the centre of the rear face 52 and the connection 56 is provided into which a gas or air supply tube can be pushed. A chamber 58 is formed inwardly of the venturi 54 by a plate 60 which carries an aerosol nozzle 62 in line with the venturi 54. Further in line with the aerosol outlet 52 is a baffle plate 64 for coalescing large droplets.

The plate 60 carries a portion 66 which forms a capillary channel 68 from the solution 70 in the base of the casing 50 whereby solution is drawn into the air flow to form the aerosol.

The casing 50 includes an intermediate plate 72 which carries a tubular section 74. The tubular section 74 has an inner cylindrical portion 76. This extends sufficiently into the casing 50 so that should the patient lean backwards so that the nebuliser has its mouthpiece downwards, solution 70 does not flow directly out of the casing 50 but is caught by the section 76. On the other side of plate 72 the tubular section 74 comprises a shaped piece 78 of tapering section. This may be round or may be somewhat elliptical to conform with the shape of the nebuliser mouthpiece as described below.

The forward portion of the casing 50 is provided with air inlet holes 80 arranged around its periphery.

If a patient is breathing normally only a small proportion of air intake is required to be drawn through the nebuliser. In the device shown in Figure 3 the extra air is taken in through the holes 80 where it entrains the flow through the tubular section 74 so that something approaching a lamina flow is achieved without undue turbulence. This improves the take-up of aerosol by the patient in the bronchial regions. The front face 82 of the nebuliser unit is extended beyond the periphery of the casing 50 and carries directly an integrally moulded mouthpiece 84.

It will be appreciated that when used by the patient the dead space between the mouthpiece and the venturi is reduced to an absolute minimum, while providing for an entrained lamina flow of aerosol into the patient's mouth. The unit is furthermore particularly convenient to use and can be filled by orientating the unit with the mouth piece uppermost and dropping the solution directly into the mouthpiece whence its travels through the tubular section 74 into the interior of the unit. To this end the forward end of section 78 may preferably have a similar shape to the forward end of the mouthpiece 84.

The unit is designed to be made simply and cheaply and can, therefore, be disposable. The need for complex screw-threaded portions is eliminated.

Figure 4 shows a modification of the unit illustrated in Figure 3 adapted to operate continuously. In this instance a further inlet 90 is provided in the rear face 52 of the nebuliser to which is preferably attached a small tube 92 leading down into the solution 70. The supply of solution can be maintained through this inlet 90 from a conventional dropper system.

The unit is otherwise similar to that of Figure 3 except that the mouthpiece is now more substantial as it will be in continuous use and preferably supports the entire weight of the nebuliser unit. To this end the casing outlet 94 is cylindrical in shape and carries a separate mouthpiece member 96 which may be of rubber or other suitable material.

Again the nebuliser has the advantage of a relatively small volume of dead space, even flow through the outlet due to the entraining of the aerosol by the additional air through apertures 80, and futhermore enables a patient to be given a continuous steady dose of drug providing optimum blood levels of the active element over a continuous period of time.

To assist in supporting the continous unit of Figure 4, a downwardly extending arm 98 may be provided which rests on the patient's chin.

Claims (7)

1. A nebuliser unit comprising a casing defining a main chamber for containing active solution and having an aerosol outlet, and a subsidiary chamber arranged around the aerosol outlet of the main chamber, the unit including an aerosol chamber into which a venturi opens and into which solution in the main chamber can be drawn to form an aerosol, and the subsidiary chamber having inlet means whereby air can be drawn into the subsidiary chamber for dilution and entraining of the aerosol flow from the main chamber.

2. A nebuliser unit according to claim 1, in which the casing is substantially cylindrical and is designed for use with the longitudinal axis thereof substatially horizontal.

3. A nebuliser unit according to claim 1 or 2, in which the main and subsidiary chambers are separated byan annularwall.

4. A nebuliser unit according to claim 1,2 or 3, in which the main chamber further includes a solution inlet whereby a supply of solution can be maintained continuously in the main chamber in use of the unit, and the casing having means including a mouthpiece whereby the unit can be continuously supported on a patient's face.

5. A nebuliser unit comprising a casing defining a main chamber for containing active solution and having an aerosol outlet, and an aerosol chamber into which a venturi opens and into which solution in the main chamber can be drawn to form an aerosol, the main chamber futher including a solution inlet whereby a supply of solution can be maintained continuously in the main chamber in use of the unit, and the casing having means including a mouthpiece whereby the unit can be continuously supported on a patient's face.

6. A nebuliser unit according to claim 4 or 5, in which the means for supporting the unit comprises a mouthpiece and a member for resting on a patient's chin.

7. A nebuliser unit substantially as herein described with reference to Figure 3 or Figure 4 of the drawings.