GB2458131A

GB2458131A - Oxygen therapy apparatus

Info

Publication number: GB2458131A
Application number: GB0804052A
Authority: GB
Inventors: Khashayar Poormand
Original assignee: Flexicare Medical Ltd
Current assignee: Flexicare Medical Ltd
Priority date: 2008-03-04
Filing date: 2008-03-04
Publication date: 2009-09-09
Anticipated expiration: 2028-03-04
Also published as: GB2458131B; GB0804052D0

Abstract

An oxygen therapy apparatus includes a connector (1) having first, second and third openings in fluid communication with one another, the first opening (5) being arranged to be coupled to an oxygen supply and the second opening (3) being arranged to be coupled to patient airway device, wherein the third opening (13) is coupled to an exhaust bag (15) having an exhaust port (17) formed therein, the exhaust bag being formed of a flexible material such that the exhaust bag collapses on itself and seals the exhaust port (17) when negative pressure is present at the third opening (13).

Description

OXYGEN THERAPY APPARATUS

Oxygen is essential for normal respiration in aerobic organisms, such as humans and animals. Upon entering the lungs, oxygen molecules dissolve into the lung tissues and pass into the blood stream. Following the transport of the oxygen molecules (bound to the haemoglobin in the blood) to various tissues, the oxygen diffuses into those tissues for metabolism. Oxygen therapy is administered to patients when they have low blood oxygen levels. Oxygen therapy benefits the patient by increasing the supply of oxygen to the lungs and thereby increasing the availability of oxygen to the body tissues.

Oxygen therapy devices for patients who are breathing spontaneously (i.e. are not in respiratory arrest) fall into two categories, variable performance and fixed performance.

Variable performance devices administer uncontrolled oxygen therapy, in as much the final oxygen concentration delivered to the patient is unknown. The resulting oxygen concentration provided by variable performance devices varies not only on a breath by breath basis, but also from patient to patient. Fixed performance devices provide a controlled, i.e. known, fixed and selectable, oxygen dosage. They create a constant proportion of air/oxygen mixture in excess of patient respiratory flow rate and are independent of patient factors.

With fixed performance devices it is desirable to avoid rebreathing, which is where the patient inhales a proportion of the carbon dioxide previously exhaled in the preceding breath. In fixed performance devices utilising a face mask that is placed over the patient's nose and mouth, the prevention of rebreathing is achieved by providing one or more exhalations vents in the face mask away from the patient's airway, and also arranging for the oxygen/air mixture to flow directly towards the nose and mouth of the patient. As the patient exhales the expelled gases exit the face mask througI the exhalation holes, often assisted by the incoming oxygen/air mixture. However, it is not always appropriate or possible to use a face mask, for example such as when the patient is fitted with an endotracheal tube (a tube passing down the patient's throat and airway). It would therefore be advantageous to provide a fixed performance oxygen therapy apparatus that substantially prevented rebreathing without the use of a face mask.

According to a first aspect of the present invention there is provided an oxygen therapy apparatus comprising a connector having first, second and third openings in fluid communication with one another, the first opening being arranged to be coupled to an oxygen supply and the second opening being arranged to be coupled to patient airway device, wherein the third opening is coupled to an exhaust bag having an exhaust port formed therein, the exhaust bag being formed of a flexible material such that the exhaust bag collapses on itself and seals the exhaust port when negative pressure is present at the third opening.

Additionally, the exhaust bag may include one or more further exhaust ports.

Additionally or alternatively, the or each exhaust port may comprise a hole formed in the exhaust bag located distally from the third opening.

Preferably the exhaust bag is formed from a substantially transparent material.

Additionally or alternatively, the first opening may include a venturi barrel in fluid communication with the atmosphere. Preferably the venturi barrel is detachable from the connector.

Preferably the connector comprises a T-piece.

Embodiments of the present invention will now be described below, by way of non-limiting illustrative example only, with reference to the accompanying figure, of which: Figure 1 schematically illustrates an oxygen therapy apparatus according to an embodiment of the present invention.

An embodiment of the present invention is schematically illustrated in Figure 1. A connector 1 is provided with three interconnected openings in fluid communication with one another. In a preferred embodiment the connector is a T-piece. The first opening 3 is arranged to be attached to a variety of known airway devices such as an endotracheal tube or laryngeal mask. A second opening 5 is attached to a venturi barrel 7 that is in turn provided with an inlet 9 arranged to be connected to a supply of 100% oxygen. The venturi barrel 7 has one or more venturi openings 11 formed in its side wall and in fluid communication with the connector 1. When connected to a 100% oxygen supply the venturi openings 11 draw in a predefined and controlled percentage of fresh air creating a mix of air and oxygen with a known percentage of oxygen. The venturi barrel may be of the kind that can be rotated so as to deliver different fixed oxygen concentration. Such venturi barrels are known. At the opposite end of the connector to the second opening 5 is a third opening 13. For the avoidance of doubt, when a connector comprises a T-piece, the second and third openings of the connector are longitudinally aligned along a common axis, whilst the first opening 3 as a longitudinal axis substantially at 900 to that of the second and third openings.

The third opening 13 of the connector is coupled in a fluid tight manner to an exhaust bag that has one or more exhaust ports 17 formed therein. In preferred embodiments the exhaust bag 15 is formed from a thin flexible material, such as HDPE (High Density Polyethylene), LDPE (Low Density Polyethylene) or PVC (Poly-Vinyl Chloride). In use, when a patient exhales a mixture of the exhaled gases and the air/oxygen mixture provided by the venturi barrel 7 flows into the exhaust bag 15 via the third opening 13 of the T-piece and subsequently is exhausted from the exhaust bag 15 through the exhaust port 17 due to the positive pressure induced within the exhaust bag. During exhalation the flexible exhaust bag 15 is fully or partially inflated. When the patient inhales the low pressure formed in the first opening 3 of the T-piece I causes the air/oxygen mixture provided by the venturi barrel 7 to flow through the first opening 3, and thus to the patient, rather than through the third opening 13 connected to the exhaust bag 15. The resulting drop in pressure at the third opening 13 of the T-piece passageway causes the flexible exhaust bag to collapse in on itself, thus substantially sealing the exhaust port 17 and preventing any ingress of ambient air to the patient via the exhaust bag. Although in theory the contents of the partially inflated exhaust bag 15 could be inhaled by the patient before the bag collapses and seals the exhaust port 17, the flow of air/oxygen from the venturi barrel 7 through the exhaust bag 15 during the patient's exhalation and pause phases causes the exhaled gases to be flushed from the exhaust bag 15 through the exhaust port 17 such that the contents of the partially inflated bag 15 after exhalation and during the pause phase of the patient is flushed and the exhaust bag is filled with fresh air/oxygen mixture from the venturi barrel. Whilst the volume of the exhaust bag is not critical to the correct functioning of embodiments of the present invention, it is preferred to use a small bag (relative to the expected average volume of exhaled gases) to ensure the exhaust bag inflates easily and does not obstruct the patient in any way.

In preferred embodiments the exhaust bag of the present invention is formed from two flat sheets of flexible material cut to the desired outline of the bag and sealed around their edges, with the exception of the opening through which the T-piece passage enters into the exhaust bag. The exhaust port(s) are formed by punching one or more holes in the distal section of the sealed exhaust bag, or in an alternative embodiment (not shown) be formed by leaving a portion of the distal seam of the exhaust bag unsealed. In any embodiment the total surface area of the exhaust port(s) 17 is arranged to be larger than that of the third opening of the connector I to prevent any back pressure within the connector. The flexible material is preferably substantially clear such that the formation of any mist arising from moisture in the patient's exhaled breath can easily be seen, the advantage being that the formation of such mist is used as evidence of the breathing function of the patient. In further embodiments the exhaust bag 15 may be formed with one or more additional exhaust ports 19 provided for safety purposes, such that should one of the exhaust ports become blocked the expired gases can still be vented through the remaining exhaust ports.

An advantage of the use of an exhaust bag according to embodiments of the present invention over a conventional one-way valve is that the inflation of the exhaust bag by the exhaled gases provides an easy indication both that the patient is breathing and that the device is functioning properly. If a conventional one-way valve were to become stuck closed it may not be easily or quickly spotted by a carer, thus potentially putting the patient at risk.

The provision of an oxygen therapy device according to the present invention provides fixed performance oxygen therapy devices that prevent patient rebreathing and which can be attached to existing airway devices.

Claims

CLAIMS1. Oxygen therapy apparatus comprising a connector having first, second and third openings in fluid communication with one another, the first opening being arranged to be coupled to an oxygen supply and the second opening being arranged to be coupled to patient airway device, wherein the third opening is coupled to an exhaust bag having an exhaust port formed therein, the exhaust bag being formed of a flexible material such that the exhaust bag collapses on itself and seals the exhaust port when negative pressure is present at the third opening.
2. The oxygen therapy apparatus of claim 1, wherein the exhaust bag includes one or more further exhaust ports.
3. The oxygen therapy apparatus of claim I or 2, wherein the or each exhaust port comprises a hole formed in the exhaust bag located distally from the third opening.
4. The oxygen therapy apparatus of any preceding claim, wherein the exhaust bag is formed from a substantially transparent material.
5. The oxygen therapy apparatus of any preceding claim, wherein the first opening includes a venturi barrel in fluid communication with the atmosphere.
6. The oxygen therapy apparatus of claim 5, wherein the venturi barrel is detachable from the connector.
7. The oxygen therapy apparatus is any preceding claim, wherein the connector comprises a T-piece.