NEBULIZER APPARATUS FOR HIGH-HUMIDITY OXYGEN THERAPY

Abstract: A nebulizer apparatus (1) for high-humidity oxygen therapy, being of a type which comprises a sealed container (2) containing water (18) for nebulization, a nebulizer (9) drawing from the container and being in fluid communication with a gaseous mixture supply, and a delivery conduit (7) for the humidified mixture, is characterized in that it further comprises an antibacterial filter (14) connected in the flow path of said humidified mixture downstream from the nebulizer.

Description: NEBULIZER APPARATUS FOR HIGH-HUMIDITY OXYGEN THERAPY DESCRIPTION Field of the Invention This invention relates to a nebulizer apparatus for high- humidity oxygen therapy, being of a type which comprises a sealed container, containing water for nebulization, a nebulizer drawing from the container and being in fluid communication with a supply of a gaseous mixture, and a delivery conduit for the humidified mixture. The invention particularly, but not solely, concerns a nebulizer apparatus for medical use in an environment of intensive therapy and/or care, and the following description will make reference to that field of application for simplicity of illustration. Background Art It is a known fact that, in the specific field of application of this invention, there exists a need for supplying patients or invalids subjected to such therapy with an oxygen/air mixture enriched with awater mist. The finely divided water ensures, in fact, proper humidity of the mixture being inhaled by the patient. It is also very important that the mixture be supplied under aseptic conditions, to prevent formation of bacterial growths that could be delivered to .the patient, already in a weakened state of health, and generate new pathologies. To meet this demand, the prior art has proposed the use of nebulizers connected to sterile water containers from which they draw through a Venturi pipe arrangement. Such prior apparatus, while being widely employed, are not devoid of disadvantages, and fall short of fully meeting the above-outlined requirements. In the first place, the air drawn in directly from the environment, through the Venturi arrangement, may itself be a source of bacterial load and, since bacterial and viral elements are used to grow at a fast rate in a medium having a high moisture content, it appears that prior art nebulizers can hardly be regarded as really aseptic. Further, the use of containers or bottles of sterile water is definitely cost-intensive. In fact, this class of products for medical applications have such specific features that make them significantly expensive and certainly not universally available items. The underlying technical problem of this invention is to provide a nebulizer apparatus for oxygen therapy which such features as to obviate the above-mentioned drawbacks with which the prior art is beset. Disclosure of the Invention The solutive idea on which this invention stands is that of providing an appropriate filtering of possible bacterial elements somewhere along the flow path of a high-humidity mixture supplied to a patient. Based on this solutive idea, the technical problem is solved by a nebulizer apparatus, as previously indicated, comprising an anti-bacterial filter installed in the flow path of the humidified mixture downstream from the nebulizer. Such inventive apparatus allows the use of non-sterile water in the nebulizer. This does away both with the need to provide expensive pre-filled containers of sterile water or a comprehensive anti-bacterial filter for all the mixture components. This advantageous feature reflects in an ability to produce a sterile mixture on line with individual application requirements. The features and advantages of a nebulizer apparatus according to the invention will become apparent from the following detailed description of an embodiment thereof, given by way of non-limitative example with reference to the accompanying drawings. Brief Description of Drawings Figure 1 is a perspective view of a nebulizer apparatus according to the invention; Figure 2 is a vertical and partial section view of the nebulizer in Figure 1; and Figure 3 is a perspective view of a further embodiment of a nebulizer apparatus according to the invention; Figure 4 shows schematically and in vertical section a detail of the figure 3 embodiment, shown in operation. Modes for Carrying Out the Invention With reference to the drawing figures, generally shown at 1 is a nebulizer apparatus for oxygen therapy according to the invention and particularly, though not exclusively, intended for medical applications in a high- humidity sterile medium. The nebulizer 1 comprises a rigid container 2, basically cup-shaped, which is formed preferably from polycarbonate and has a closure cover 3 threaded removably thereon. The cup 2 contains water 18 for nebulization useful to prepare a high-humidity gaseous oxygen/air mixture to be administered to a patient 20 undergoing intensive therapy or care. Provided on the cover 3 is a first fitting 4 for connection to an oxygen supply, not shown because conventional. The connection of the supply to the fitting would be established by means of a tube 16. The fitting 4 is incorporated to a Venturi device 5 whereby ambient air is admixed to the oxygen from said supply. The incoming air flows through a port 13 which can be restricted by means of a ring nut 19. Beneath the cover 3, the Venturi device 5 is in fluid communication with a slightly offset nebulizer 9 having an extension tube 10 fitted thereover for admitting water to be nebulized. This tube 10 draws from a point close to the bottom 12 of the cup 2. Provided on the nebulizer 9 is also a choke device 17 effective to boost the velocity of the mixture flow to the patient 20. The cover 3 includes additional fittings, and specifically at least one water filler cap 6 and a second inlet 8 for optional insertion of a resistance heater. Advantageously, the apparatus 1 further comprises a delivery conduit 7 which has one end connected to the cover 3, through a connection element 24, and is in fluid communication with the interior of the cup 2. The other end 15 of the conduit 7 is free and adapted to be presented to the patient 20. Conveniently included in the fluid path addressed to the patient, an anti-bacterial sterilizing filter 14 is provided according to the invention. The filter 14 includes a hydrophobic or water-repellent membrane 21 formed from a very thin sheet of a microporous plastics material. More specifically, the membrane 21 is mounted inside the container 2 and associated with the cover 3. The membrane 21 is secured around the inner peripheral edge of the cover 3 in order to establish an aseptic barrier between the nebulizer 9 and the port in the cover 3 for the delivery conduit 7. Thus, a nebulization chamber 22 is defined within the container 2 which extends between the free surface of the water 18 and the membrane 21. Defined within the cover 3 is instead a receiving header 23 for the humidified mixture. This header 23 directs the mixture to the port in the cover 3 for the conduit 7. In a preferred embodiment, this membrane 21 is formed from ethylene polytetrafluoride (PTFE) and has a pore size of less than 10 μm (0.01 mm). A peculiar feature of this membrane 21 is that it allows a large flow of humid air through its pores, but blocks particles, particulate matter, bacteria, and aerosol droplets. In essence, the membrane 21 allows only humid air/oxygen to pass through and prevent aerosol droplets from reaching the patient. The membrane 21 also arrests bacteria, viruses, and any corpuscles other than in a gaseous state. Actual tests have shown that the membrane 21 can function as a filter with an efficiency in excess of 99.9999% for fluids containing smaller size particles than 0.1 μm. The membrane is preferably realized with a very fine fibril structure of GORE-TEX. With specific reference to the embodiment shown in Figure 3, a further embodiment of the nebulizer apparatus according to the invention will now be described wherein parts and co-operating portions previously illustrated carry the same reference numerals. In this variant, the anti-bacterial sterilizing filter 14 is conveniently included in the fluid path bounded by the conduit 7 and housed within a sealed case. More particularly, the filter 14 is housed within a case formed of a pair of funnel-shaped members 11 being identical with each other and sealed around the peripheral edge of their flared portion, as shown in figure 4. This case is connected in the conduit 7 by a quick- connect arrangement including oppositely directed hose attachment ends. The membrane 21 is held centrally between the opposed shells represented by the two sealing members 11. A primary advantage of the inventive apparatus is that it allows for the use of non-sterile water in the nebulizer. This does away both with the need to provide expensive pre-filled containers of sterile water or comprehensive anti-bacterial filter for all the mixture components. This advantageous feature reflects in an ability to produce a sterile mixture on line with individual application requirements. In other words, the apparatus of this invention can be "tailored" to the individual patient. Another major advantage is that the membrane would in any case be associated with the apparatus cover 3, thereby the water chamber 18 in the cup 2 can be filled without interfering with the aseptic barrier 21. In addition, the filter membrane is inserted removably in the mixture delivery conduit to the patient, and accordingly, easily replaced for customary maintenance and cleaning operations. Understandably, the apparatus of this invention may be modified and altered within the scope of the following claims.

Claims: CLAIMS 1. A nebulizer apparatus for high-humidity oxygen therapy, being of a type which comprises a sealed container, containing water for nebulization, a nebulizer drawing from the container and being in fluid communication with a supply of a gaseous mixture, and a delivery conduit for the humidified mixture, characterized in that it further comprises an anti¬ bacterial filter (14) installed in the flow path of said humidified mixture downstream from the nebulizer. 2. A nebulizer apparatus according to Claim 1, characterized in that said filter (14) is inserted in the humidified mixture delivery conduit (7). 3. A nebulizer apparatus according to Claim 1, characterized in that said filter (14) is a hydrophobic or water-repellent membrane (21). 4. A nebulizer apparatus according to Claim 3, characterized in that said membrane (21) is formed from a thin sheet of a synthetic plastics material having a smaller pore size than 0.01 millimeters. 5. A nebulizer apparatus according to Claim 3, characterized in that said membrane (21) is made of ethylene polytetrafluoride. 6. A nebulizer apparatus according to Claim 1, characterized in that said filter is housed within a case (11) which fits removably in the delivery conduit (7) by means of a quick-connect arrangement. 7. A nebulizer apparatus for high-humidity oxygen therapy, being of a type which comprises a container containing water for nebulization and being closed by a cover, a nebulizer drawing from the container and being in fluid communication with a gaseous mixture supply, characterized in that it further comprises an anti¬ bacterial filter (14) attached to said cover (3) and providing a barrier between the nebulizer (9) and the delivery conduit (7). 8. A nebulizer apparatus according to Claim 7, characterized in that said filter (14) is a hydrophobic or water-repellent membrane (21). 9. A nebulizer apparatus according to Claim 8, characterized in that said membrane (21) is formed from a thin sheet of a synthetic plastics material having a smaller pore size than 0.01 millimeters. 10. A nebulizer apparatus according to Claim 8, characterized in that said membrane (21) is made of ethylene polytetrafluoride.

Inventors: GOLDBERG WENDY, PARATICO ROBERTO, GOLDBERG, WENDY, PARATICO, ROBERTO
Applicants: FLOW METER SPA, GOLDBERG WENDY, PARATICO ROBERTO, FLOW-METER S.P.A.
Application year: 1992
Main classification: A61M16
IPC codes: A61M11, A61M16