NEBULIZER

Abstract: A nebuliser comprising a pressure gas inlet (12), means (18) for passing liquid medication to nebulising means (20) associated with said pressure gas inlet to mix gas from the pressure gas inlet with said liquid medication to produce a nebulised mixture of liquid and gas, means (36) to supply further gas, to mix with said nebulised mixture, said further gas supply means including a control means (43) to control said supply of said further gas.

Description: NEBULIZER The present invention relates to nebulizers. Nebulizers are used to produce a liquid m fine droplet form in a gas flow, typically a liquid in the form of medication which is to be entrained in an air or oxygen gas flow and which is then breathed by a patient whereby the medication is supplied to the patient through the lungs. Nebulizers are becoming widely used in hospitals and other medical situations. Such nebulizers have particular application in the delivery of drugs for the treatment of lung diseases. Thus ±e drug may be given as an inhaled drug aerosol, and this has many advantages over drugs which are taken systemically. It has become apparent that the size of the droplets plays an important role in how the drug is received by the lungs. European Patent specification EP-A-573457 demonstrates a typical nebulizer and there is included in that specification details of the effect of droplet size on the delivery of the medicauon. The present invention provides a nebulizer comprising a pressure gas inlet, means for passing liquid medication to nebulising means associated with said pressure gas inlet to mix gas from the pressure gas inlet with said liquid medication to produce a nebulized mixture of liquid and gas, means to supply further gas, which may be ambient air, to mix with said nebulized mixture, said further gas supply means including a control means to control said supply of said further gas. The nebulizer may include a reservoir for said liquid medication, and the control means may include means to vary the size of the supply means so as to vary the amount of further gas passing through said further gas supply means. The control means may be in the form of a variable aperture, which may be provided by an aperture with a plate with a cooperating aperture therein, the plate being moveable. The control means may also include a one way valve. An advantage of the arrangement of the invention is that the quantity and relative constitution of the nebulized mixture may be changed by varying the control means to control the supply of further gas. By providing the control means at the input to the nebuliser, there is less risk of these control means being contaminated with medication. A nebulizer incoφorating a preferred embodiment of the invention will now. be described by way of example only with reference to the accompanying drawings in which:- Figure 1 is a axial section through a nebulizer according to the invention, Figure 2 is a perspective view of the nebulizer of Figure 1 from the right hand side with an air controller in a first position, similar to the position shown in Figure 1 , Figure 3 is a view similar to Figure 2 of the nebulizer with the air controller in a second position, Figure 4 is a view corresponding to Figures 2 and 3 of the nebulizer, with the air controller missing, showing the inlet air valve, Figure 5 is a pan view showing one line of ratchet teeth mounted on the nebulιzer( with air controller missing), and, Figure 6 is rear view of the air controller showing the teeth to engage the ratchet shown in Figure 5. Referring to Figure 1 , there is shown an axial section through a nebulizer (10). The section shown in Figure 1 , compπses, on the left hand side of the Figure 1 , a first veπical section, and on the πght hand side of the Figure a second veπicaJ section at πght angles to the first The nebulizer is manufactured of πgid moulded plastics mateπal. The nebulizer compnses a base section (1 1) which includes an inlet tube ( 12) for connection to a flexible plastic tube supplying pressurized gas, such as oxygen or air. The inlet tube (12) is sunounded by a threaded collar (13). Surrounding the pan of the inlet tube (12) which extends into the base section (11) is a reservoir (14) for liquid medication. Forming pan of the base section ( 1 1) but separately moulded is a second moulding ( 16) which includes; (a) a cylindncal stem portion (17) which closely sunounds the inlet tube (12) where it protrudes into the reservoir (14) and provides therebetween a capillary path (18) from the base of the reservoir (14) to the top of the inlet tube (12). (b) a jet mounting portion ( 19) which includes a jet (20A) which overlies a jet (20B) in the upper end of the inlet (12); and (c) a collar portion (21 ) which comprises a frusto conical plate (22) surrounding the jet mounting poπion (19) and mounted thereon by legs (25). The inner generally cylindrical surface (21A) of the collar portion (21) immediately sunounding the jet comprises a frusto-conical surface of the apex of which is below the collar and is at an angle of about 8° to the axis. The jet (20A) and jet (20B) combine to provide a gas/liquid mixing jet (20). An upper section (26) screw threadedly engages with the upper edge of the base section (1 1) and comprises an outer housing (27) at the upper end of which is provided an outlet (28) for air and nebulized medication, and within the housing (27) is mounted a cylindrical stub (29) which forms a target (31) disposed immediately opposite the jet (20) , the cylindrical stub (29) being sunounded by a downwardly extending collar (32) which engages axially with the collar portion (21). The collar (32) communicates via pathways (33, 34) with an ambient air inlet (36) mounted on the side of the outer housing (27). The ambient air inlet (36) is closed by a one way valve (37) in the form of a flexible diaphragm (38) of plastic, neoprene, or rubber mounted centrally at (39) and which engages with a rim (41) sunounding the ambient air inlet (36). The ambient air inlet (36) includes a circular opening (42) defined by the rim (41) and an adjustable air controller (43) is provided to selectively obscure the circular opening (42) as will be described hereafter. The adjustable air controller (43) comprises a plate like member (44) mounted to slide vertically with respect to the housing (27) and includes an aperture (46) which, as the plate (44) slides, may selectively align with the circular opening (42). Figure 2 shows the general arrangement of the plate (44), in a first position in which the air inlet (36) is closed and Figure 3 shows the plate (44) in a second position in which the air inlet (36) is open. Figures 4 shows the nebulizer with the plate (44) removed thereby showing more clearly the circular opening (42). On each side of the opening (42) there is moulded into the outer housing (27) a pair of vertically extending edges (47, 48) which each include a respective ratchet track (51 , 52) which are illustrated in more detail in Figure 5. Spaced from and aligned into the conesponding vertically extending edges (47, 48), the plate (44) has veπically extending faces (53, 54) illustrated in Figure 6. Each face (53.54) includes a respective upper and lower tooth (56, 57) for engaging with the respective adjacent ratchet track (51 , 52). In operation the base section ( 1) and upper section (26) are separated and suitable medication is poured into the reservoir (14) of the base section (1 1). The base section (1 1) and upper section (26) are then reengaged in a manner shown in Figure 1, inlet tube (12) is connected by means of a flexible plastic pipe to a suitable pressurised supply of air or oxygen and the outlet (28) is connected, usually by tubes, to a patient. The plate (44) is slid up or down so that the aperture (46) coincides with the circular opening (42) to a desired extent and is held in the desired position by engagement of the teeth (56,57) with their respective ratchet tracks (51 ,52). The liquid medication passes from top reservoir (14) up the capillary path (18) and as the pressurised air or oxygen passes through the jet (20B), mixes with the liquid passing up the capillary path (18) and together pass through the jet (20A), the nebulised gas/liquid jet then striking the target (31) to break up the liquid panicles. The aerosol formed then passes down between the jet mounting portion (19) and the inner surface of the frusto conical plate (22). The frusto conical plate (22) and the inner cylindrical surface (21 A) of the collar (21 ) collect the remaining larger droplets in the nebulized stream (which take a different, less tortuous trajectory and thus strike these surfaces) and the nebulized stream then passes up through the outlet (28). The collected liquid drips off the lowermost edge of the collar (21) back into the reservoir (14). In addition to the nebulized stream, air is drawn into the ambient air inlet (36) via the one way valve (37), through the pathways (33,34) to join and mix with the nebulized stream assisting in the breaking up of the gas liquid stream into finer droplets and in increasing the aerosol output being delivered through the outlet (28). It will be understood, therefore, that by varying the amount of air drawn into the ambient air inlet (36) by sliding the adjustable air controller (43) plate (44) up and down, one can vary the proportion of medication to air. By arranging the adjustable air controller (43) at the air inlet, one avoids a number of problems. For example as most of the nebulized stream passes out of the outlet of the nebulizer, very little if any of the nebulized liquid will be deposited on the adjustable air controller, which would otherwise be a problem.

Claims: CLAIMS 1. A nebuliser comprising a pressure gas inlet (12), means (18) for passing liquid medication to nebulising means (20) associated with said pressure gas inlet to mix gas from the pressure gas inlet with said liquid medication to produce a nebulised mixture of liquid and gas, means (36) to supply further gas, to mix with said nebulised mixture, said further gas supply means including a control means (43) to control said supply of said further gas. 2. A nebuliser as claimed in claim 1 in which the control means includes means to vary the size of the supply means so as to vary the amount of further gas passing through said further gas supply means. 3. A nebuliser as claimed in claimed 1 or 2 in which the control means is in the form of a variable aperture, provided by an aperture with a plate with a cooperating aperture therein, the plate being moveable. 4. A nebuliser as claimed in claim 1 in any of claims 1 to 3 in which the control means includes a one way valve. 5. A nebuliser as claimed in any of claims 1 to 4 including a reservoir for said liquid medication. 6. A nebuliser as claimed in claim 1 substantially as hereinbefore described with reference to the drawings.

Inventors: JASSELL SURINDERJIT KUMAR, JASSELL, SURINDERJIT, KUMAR
Applicants: INTERSURGICAL LTD, JASSELL SURINDERJIT KUMAR, INTERSURGICAL LIMITED, JASSELL, SURINDERJIT, KUMAR
Application year: 1996
Main classification: A61M11
IPC codes: A61M11