REBREATHING BAG INHALERThe subject of this invention is a rebreathing bag for metereddose inhalers and oxygen.
Breathing with inhalers depends mainly on good coordination between the inhaler and respiration, a technique which renders them unsuitable for use with children. It is a well-known fact that using inhalers with adults under the most ideal conditions, 80% of the aerosol medication goes no further than the upper respiratory tract and a mere 10-15% reaches the lungs. Aerosol medication can also be administered in large plastic, non-flexible air-chambers, in which the air the patient breathes is sprayed, or in similar devices of a smaller diameter with masks, from which the patient inhales.
Because these devices are not air-tight, they have a reduced effectiveness due to the escape of aerosol medication.
Consequently many inhalations are required for a sufficient quantity to reach the lungs. Furthermore, such devices cannot be used on patients whose natural breathing is inhibited, such as those undergoing anaesthesia etc..
In the device in question there is a rebreathing bag for inhalants and oxygen consisting of attachments for an inhaler, together with one-way valves, which can be of any type. The aerosol medication, after spraying, is enclosed within the rebreathing bag and is inhaled almost completely when either a mask is firmly fitted over the mouth and nose, a mouthpiece is used, a tracheal tube is inserted, or by any other means. The rebreathing bag containing the medication deflates during inhalation and the valves direct the air flow to the mouth and lungs. In the event of weak breathing the air can be delivered manually by the exertion of pressure on the rebreathing bag.
The method of operation is now described with reference to the accompanying diagram.
Figure 1 is a breakdown of the various parts of the device.
Figure 2 illustrates the aerosol medication path during sprayingand inhalation.
Figure 3 shows the rebreathing bag during inhalation, afterbeing compressed with the incoming air.
Figure 4 demonstrates the manual delivery of the aerosolmedication or oxygen.
It will be seen from the diagram, Fig 1, that the rebreathing bag inhaler comprises the inlet valves for the mask, the inhaler, the oxygen 3 and the rebreathing bag. The inhaler itself 7 is fitted in the appropriate position 14 on the opposite side of the elastic bag. The valves, which can be of any type (not shown), in either metal or plastic, manual or automatic, permit the one-way flow of air either in, during spraying, or out, during inhalation.
As shown in Fig 2, valve 2 is opened by pressing button 2 and spray is admitted to the rebreathing bag. The valve is then immediately closed either manually or automatically by releasing button 2. The aerosol medication 11 is now trapped in the rebreathing bag 5. The mask 8 is now placed firmly over the mouth and nose or the mouthpiece 9 gripped between the teeth and lips to permit the intake of the inhalant contained within the rebreathing bag.
As illustrated in Fig 3, during inhalation valve 1 opens, simultaneously shutting off the escape of air, allowing free entry to the mouth and lungs. With the inhalation of air 11 the rebreathing bag deflates 4. The extent of inhalation is judged by the degree of deflation of the rebreathing bag. If inhalation is extended and the rebreathing bag is completely deflated 4 then, due to the negative pressure, valve 2 opens.
Valve 2 opens automatically, allowing the entry of air to the rebreathing bag, only if the negative pressure is greater than that needed to deflate the rebreathing bag and allow the completion of inhalation. During exhalation air 12 escapes from the side of valve 1 which, at the same time, prevents the entrance of air into the rebreathing bag.
Should the need arise to insert a tracheal tube 10 or a face mask in cases of weak breathing, then manual hand pressure 13 can be exerted on the rebreathing bag to deliver air to the lungs as illustrated in Fig 4.