GB2493162A

GB2493162A - Spirometer disposable mouthpiece valve with oval shape

Info

Publication number: GB2493162A
Application number: GB201112811A
Authority: GB
Inventors: Bernhardt Rudolph Garbe; John Marcus Garbe
Original assignee: VITALOGRAPH Ltd
Current assignee: VITALOGRAPH Ltd
Priority date: 2011-07-26
Filing date: 2011-07-26
Publication date: 2013-01-30
Also published as: GB201112811D0; DE202012007148U1

Abstract

Disposable mouthpieces for use with spirometers are disclosed. Known mouthpieces have a cylindrical cardboard tube 15, with a plastics valve unit consisting of a generally cylindrical short tubular moulding 1 which is a press fit in the interior of the cardboard tube 15, and having internally a hub 6 connected via spokes 5 to the interior wall of the tubular moulding, and a flap valve diaphragm 9 supported on the hub and against the spokes and a circular seating. The moulding 1 has an integral flange 2 to prevent the valve unit being pushed all the way into the cardboard tube. In accordance with the invention, the exterior of the flange 2 is oval, sized so it cannot be inserted into the circular aperture of the spirometer flow tube, so the mouthpiece cannot be inserted the wrong way round. The plastics body may also be oval, to distort the cardboard tube and improve the friction fit therebetween. The flange may project from the body not more than the wall thickness of the cardboard tube, so that it is not pulled off by a user after use.

Description

DISPOSABLE MOUTHPIECES

This invention relates to disposable mouthpieces, particularly for use with spirometers, though they may also be used with other medical or diagnostic equipment designed to test or monitor lung or related breathing functions.

Spirometers are a standard diagnostic tool for examining lung functioning.

They measure the flow of exhaled air from a patient, for which purposes the patient is asked to exhale into a mouthpiece.

In order to minimise the risk of cross infection when a spirometer is used by a succession of individuals whose lung function is being tested, it is customary to use disposable mouthpieces which are inserted into a flow tube leading to the spirometer apparatus itself. In order to avoid any inhalation of material which may have been exhaled by an earlier user, the mouthpieces are conventionally provided with a one-way valve, usually a simple flap valve, in order to ensure that the user cannot inhale through the mouthpiece when the spirometer is being used.

Because the mouthpieces are designed to be disposable, it is desirable to provide mouthpieces which are inexpensive while remaining effective. A standard design has evolved being a cardboard tube, one end of which is a press fit in a tube leading to the spirometer and the other end of which carries an inserted valve member. The valve member is conventionally made of a plastics moulding, generally in the form of an elongate cylinder having moulded in its interior a number of spokes radiating from a central hub where one end of the hub carries a stud on which a circular diaphragm is mounted.

The spokes and an annular shoulder formed in the plastics moulding act as a seating against which the circular diaphragm lies, until the user blows exhaled air through the cylindrical moulding, past the spokes and into the cardboard tube leading to the spirometer.

The relevant standards (ISO 23747 and ISO 26782) require that any operator-detachable components which are flow direction sensitive must, unless they are designed in such a way as to prevent incorrect use or assembly, bear a symbol showing the direction of flow. Providing such a symbol adds to the cost and additionally may require, for example, a special coating or the like on the exterior of the cardboard tube in order to render it capable of accepting a printed flow direction marking, and any such material must be food grade because the exterior of the mouthpiece comes into contact with the patient's mouth.

One way of avoiding the need to mark is to ensure that the mouthpiece cannot be inserted into the tube leading to the spirometer the wrong way round, for example by making the plastics cylinder containing the valve member wider, usually by the provision of a flange. The external diameter of the flange should be sufficient to ensure that the valve end of the mouthpiece cannot be inserted into the socket on the tube leading to the spirometer itself.

This, however, brings with it a disadvantage that the plastics valve unit may be pulled from the cardboard tube by the user, particularly when the tube is removed from the patient's mouth by someone other than the patient him or herself. There is a possibility that the circular flange gets caught on the teeth of the patient and it can then potentially be swallowed unless it is of a sufficient size to prevent that, but making such valve units large enough to prevent swallowing means that additional plastics material needs to be used, which is uneconomic.

We have now found that improved mouthpieces may be produced which are economic to produce, simple to deploy, impossible to insert the wrong way round, and which do not lead to a material risk of retention of the valve unit in the mouth of the user.

According to the present invention, there is provided a disposable mouthpiece consisting of a cylindricat cardboard tube having inserted into one end a plastics valve unit, the valve unit consisting of a generally cylindrical shod tubular moulding having an external diameter which is a press fit in the interior of the cardboard tube, and having internally a hub connected via spokes to the interior wall of the tubular moulding and a flap valve diaphragm supported on the hub and against the spokes and a circular seating, the diaphragm being more remote from the end of the tube into which the generally cylindrical moulding is inserted than the seating and spokes, and the generally cylindrical plastics moulding having an integral flange to prevent its being pushed all the way into the cardboard tube, and characterised in that the exterior of the flange is oval, its maximum diameter being greater than that of the cardboard tube.

One way of achieving this is to provide that the wall thickness of the cylindrical moulded portion varies between two diametrically opposed portions of minimum thickness and two diametrically oppositely located portions of maximum thickness, and that the flange extends around the entire periphery to an extent no greater than the wall thickness of the cardboard tube.

A less preferred approach is to vary the radial extent of the flange between a minimum extent equal to or less than the wall thickness of the cardboard tube and a maximum extent materially larger than that thickness, for example twice the thickness of the cardboard tube.

Disposable mouthpieces according to the invention accordingly have one circular end, i.e. the end of the cardboard tube, and one oval end of larger diameter, which prevents the oval end being inserted into the socket designed for receipt of the cardboard tube located on the spirometer or analogous device. This enables any flow direction marking to be dispensed with, so keeping the cost of the unit down.

Additionally, because of the fact that the end of the mouthpiece which is inserted into the patient's mouth has no projecting flange, or one which projects only in two diametrically opposed regions, the risk of the valve unit being pulled out of the cardboard tube is very substantially diminished, as in the first case there is no risk of the flange catching on the teeth of the patient, as it does not project past the cardboard tube, and in the second the nurse or like practitioner attending to the patient can ensure that the projecting flanges are towards the sides of the patient's mouth rather than extending vertically.

Accordingly the mouthpiece may be removed without discomfort and without the risk of becoming detached from the cardboard tube. The entire unit can then be disposed of in the usual way.

In the preferred version of putting the invention into effect noted above, there is an additional factor which reduces the risk of valve unit and cardboard tube separating: because of the various wall thickness, the exterior of the valve member is oval and distorts the tube when push-fitted into its end, thus improving the grip between them.

The invention is illustrated by way of example with reference to the accompanying drawings in which: Figure 1 is a perspective view from one end of a preferred embodiment of plastics valve insert for use in a disposable mouthpiece according to the present invention.

Figure 2 is a view of the valve insert as shown in Figure 1 from the opposite end.

Figure 3 is a perspective view of a preferred embodiment of the disposable mouthpiece in accordance with the invention; and Figure 4 is a section along the lines A-A shown in Figure 3.

Referring to the drawings, Figures 1 and 2 show in perspective and from opposite ends a generally cylindrical moulded plastics one-way valve unit, with the diaphragm removed for the sake of clarity. The general structure is that of a hollow cylindrical body 1 having a flange 2 at one end and a chamfer 3 at the opposite end. The interior of the hollow body is of cylindrical shape. Moulded integrally with cylindrical body 1 and flange 2 are four radial spokes 5 which support a central boss 6. The end of boss 6, as can be clearly seen in Figure 2, constitutes a conical head over which a circular aperture in the centre of a flexible circular diaphragm may be fitted. The diaphragm is denoted 9 and shown in Figure 4. When so inserted, diaphragm 9 lies against the faces of spokes 5 which are visible in Figure 2 as well as against four projections 7, integrally moulded with cylindrical body 1, and a circular rim 8.

As can be clearest seen in Figure 1, the radial extent of flange 2 is a minimum at the areas denoted 10 and a maximum at the areas denoted 11.

However, the external projection of flange 2 from the outer wall of body 1 is substantially even, as shown in Figure 2, denoted 12. This is because the wall thickness of body 1 varies, thickest at parts B and thinnest at parts C, as indicated on Figure 1.

The valve unit shown in Figures 1 and 2 may be press fitted into a cardboard tube 15 which is shown in Figures 3 and 4. The fitting of the unit into tube 15 is facilitated by the chamfer 3 and the valve unit is pushed into tube 15 until the flange 2 comes to rest against the end of the tube 15. As can be seen in Figure 4, in that position, the flange does not project past the external diameter of the tube 15. However, because the exterior of body 1 is slightly oval, when it is inserted into tube 15, the end of the tube becomes slightly oval too, thus not only ensuring a tighter fit between body 1 and the interior of tube 15, but most importantly making the mouthpiece essentially wider, so preventing its insertion into the mouthpiece socket on a spirometer. In other words, the end of the mouthpiece denoted 18 in Figures 3 and 4 is a press fit into the mouthpiece socket on the spirometer while, if an attempt is made to push end 19 into that socket, it will fail because it is too wide. This is instantly clear to the person attempting to do so, and they then simply reverse the mouthpiece and insert the correct end into the socket. The mouthpiece is then ready, the right way round, for the patient to blow into it.

By suitable dimensional control and choice of materials, the press fitting of the valve unit shown in Figures 1 and 2 into tube 15 may be such as to render it difficult to remove from the tube, despite the fact that the axial extent of the valve unit shown in Figures 1 and 2 relative to tube 15 is small, and even if, as is preferred, no adhesive or the like is applied to the exterior of the valve unit or interior of the tube before the two are push4itted together.

The valve unit shown in the drawings has four spokes 5; other numbers of spokes may be used, though at least 3 and not more than 6 are preferred numbers.

Claims

<claim-text>CLAIMS1. A disposable mouthpiece consisting of a cylindrical cardboard tube having inserted into one end a plastics valve unit, the valve unit consisting of a generally cylindrical short tubular moulding having an external diameter which is a press fit in the interior of the cardboard tube, and having internally a hub connected via spokes to the interior wall of the tubular moulding and a flap valve diaphragm supported on the hub and against the spokes and a circular seating, the diaphragm being more remote from the end of the tube into which the generally cylindrical moulding is inserted than the seating and spokes, and the generally cylindrical plastics moulding having an integral flange to prevent its being pushed all the way into the cardboard tube, and characterised in that the exterior of the flange is oval, its maximum diameter being greater than that of the cardboard tube. c'J</claim-text> <claim-text>2. A disposable mouthpiece according to Claim 1 wherein the wall thickness of the cylindrical moulded portion varies between two diametrically opposed portions of minimum thickness and two diametrically oppositely located portions of maximum thickness, and that the flange extends around the entire periphery to an extent no greater than the wall thickness of the cardboard tube.</claim-text> <claim-text>3. A disposable mouthpiece according to Claim 2 wherein the exterior of the valve unit is oval so as to distort the cylindrical cardboard tube when push-fitted into its end whereby to improve the grip between them.</claim-text> <claim-text>4. A disposable mouthpiece according to Claim 1 wherein the radial extent of the flange varies between a minimum extent equal to or less than the wall thickness of the cardboard tube and a maximum extent materially larger than that thickness.</claim-text> <claim-text>5. A disposable mouthpiece according to Claim 4 wherein the maximum radial extent of the flange is substantially twice the thickness of the cardboard tube. (4 r (4</claim-text>