GB2200281A

GB2200281A - Straps for face masks

Info

Publication number: GB2200281A
Application number: GB8801237A
Authority: GB
Inventors: Howard Geoffrey Bellm; Richard Banfield Hicks
Original assignee: Lifeline Ltd
Current assignee: Lifeline Ltd
Priority date: 1987-01-27
Filing date: 1988-01-20
Publication date: 1988-08-03
Anticipated expiration: 2008-01-20
Also published as: GB2200281B; GB8701738D0; GB8801237D0

Abstract

The strap for a mask for administering gases or nebulized gas/liquid mixtures is moulded in one piece of non-elastic material and comprises an elastic section formed by at least one transversely disposed link which may flex to provide elastic extension of the length of the strap. In one case this is provided by an X section and in another case by a corrugated section. The edge of the mask may be roughened so as to prevent a build-up of liquid where the mask meets the face. <IMAGE>

Description

MASK AND STRAP The present invention relates to a mask preferably but not exclusively for medical use for administering gases such as oxygen and a strap which may be used, inter alia, with such a mask.

Hitherto masks have been widely used in medical practice for the application of gases or, more recently, for use with nebulization, that is the application or drugs to a patient by means of an aerosol produced by a flow of gas, the aerosol and hence the drug being breathed in through a face mask.

One of the difficulties of using such a mask is that, particularly in the case where a nebulized mixture of liquid (generally water) and gas is being applied to the patient through the mask, water will condense on the interior of the mask and, indeed, on the patients face and this water tends to become trapped between the edge of the mask and the patients face. Whilst this is only a minor problem over the course of a short period of treatment, it can become a considerable nuisance and, indeed, a medical problem in the case where a mask is applied for prolonged periods to a patients face.

A further problem is in relation to straps which may be used with masks, but may also be used in other circumstances. A particularly strong and convenient form of material for moulding a strap is a substantially non-elastic, but flexible plastic material such as polyvinyl chloride (PVC).

Clearly in many uses of a strap it is necessary for the strap to be elastic and most of the the elastic plastics which are economical are often not strong enough.

The invention, therefore, provides, according to one aspect, a mask for application to a persons face in which the edge of the mask abutting the person's face incorporates a surface with sufficient roughness to prevent the trapping of liquid between the mask and the Sace asnd-/cr to allow release of any liquid;so:traped In this way, the problem of trapping of water between the mask and the face is reduced or overcome.

Masks are generally moulded in plastics material and, in use, the part of the mould which moulds the edge of the mask is roughened by means of blasting with a grit material. The grit material may be carried by a stream gas.

In another aspect of the invention, there is provided a strap moulded of a substantially non-elastic material, the strap including a at least one transversely disposed link extending transversely to the length of the strap whereby said at least one transvrsely extending link may flex to provide an elastic extension of the length of the strap.

Preferred arrangements of the invention will now be described by way of example only and width reference to the accompanying drawings in which: Figure 1 is a perspective view of a first mask assembly according to the invention, Figure 2 is a side view of the mask assembly, Figure 3 is an end view of the mask assembly, Figure 4 is a section of a nozzle part of the mask assembly, Figure 5 is a perspective view of part of the clip means of the mask assemby, Figures 6 and 7 are plan and side views of a strap. and clip means of a second mask assembly according to the invention, and Figure 8 is a cross section on the line A-A of Fig 6.

Figure 1 illustrates a mask assembly comprising a onepiece injection moulding of plastics material (transparent, flexible, but substantially non-elastic polyvinyl chloride PVC moulded at 170-180 ). All of the parts illustrated are moulded of this plastic and no additional parts are necessary either during moulding (ie no separate metal clips etc are inserted in the mould before moulding) and no additional assembly work of clip parts or strap is necessary.The face mask assembly comprises a mask 10 incorporating a gas delivery nozzle 11, a strap 12 connected to one edge 13 fo the mask 10, and clip means 14 in two parts, one part 16 being formed at the free end of the strap 12 and the other part 17 being formed on an edge 18 of the face mask 10 opposite the edge 13 (although the part 17 could be formed on the free end of another strap attached to the edge 13 of the mask). The mask 10 also includes exhaust apertures 19.

Although the mask assembly is injection moulded in one operation of the same non-elastic PVC (polyvinyichloride) material moulded at 170-1800C, the thickness of the material and cross-section varies to allow the different parts of the face mask assembly to carry out their normal function. Thus for example the face mask 10 is generally of relatively thin material (typically l.lmm) with a flexible thin seating edge 2i surrounding the mask 10 for engagement with the face of the patient.The injection point for the injection of the plastic during the moulding is indicated at 50 in substantially he middle of the front ace of the mask i. The wa11 thickness of the 'mask 10 -is, approximately l.lmm except for the cross shaped region 51 delineated by dotted lines. Within this region 51 the thickness of the wall of the mask 10 is increased to substantially double that thickness, approximately 2mm.The thickened region 51 helps the mask 10 to maintain its shape and also allows, during moulding, plastic to more readily flow from the injection point 50 to other parts of the mould, and in particular the parts of the mould which form the strap means and the nozzle 11.

The cylindrical outer gas delivery nozzle 11 is formed of a predetermined standard dimension so as to fit with standard products such as nebulizers or venturis (typically 22 mm outer diameter with predetermined tapers to accord with international standards. There is also provided a central axial inner nozzle 62 having a standard outer diameter of 5.5 mm and a chamfered free end 63 adapted to be connected with a standard oxygen supply tube. The inner nozzle 62 is connected to the outer wall of the nozzle 11 by means of radial fingers 64 disposed at the inner end of the nozzle li.The nozzle is arranged so as to direct the gas flow through the nozzle 11 towards the nose of the person wearing the mask 10.

The cross-section and width of the strap 12 is chosen so as to provide sufficient strength for the strap. To provide a variation in the length of the strap in use, the clip portion 16 comprises, at the end of the strap 12, a plurality of spaced male parts in the form of spheres 22 linked by links 23. The other part 17 of the clip forming the female part comprises a pair of part spherical sockets 26 with which two adjacent spheres 22 may engage. The sockets 26 are formed in resilient wall portions 27 connected to a base 59 which flex to allow insertion of the spheres into the sockets 26 and the flexible wall portions 27 then flex back to their normal position to clamp the spheres 22 in the sockets 26.

Thus the effective length of the strap 12 can be adjusted by selecting the particular sphere/link combination to be engaged with the slot 24 The female part 17 of the clip means is attached to the mask 10 by means of a short length of strap 52. The form of the strap 52 is clear from the drawing and comprises a sucession of transverse links 53. the transverse links 53 form a series of "X's" the ends of the links of which are joined together. Thus, although the material from which the mask assembly is manufactured is substantially non-elastic, the strap 52 is flexible and thereby forms an elasticated section 54 hich can be resiliently expanded in length.This expansion takes place by bending of the transverse links 53 with respect to each other from the straight line form shown in the drawing to a curved form whereby the length of the strap 52 can be resiliently increased.

The strap 12 is connected, to the edge 13 of the mask 10, by means of an elasticated section 61 similar to the elasticated section 54.

The edge 21 of the face mask which engages the face of the patient wearing the mask is flexible so as to substantially seal with the patient's face. This can cause problems particulary as, during prolonged use, water tends to be trapped between this edge 21 and the skin of the patient's face. Accordingly, the surface of the edge 21 is arranged to be rough to a predetermined extent so as to prevent the close sealing of that surface with the patient's face and thereby prevent the trapping of liquid between that surface and the face and/or to allow the release of any liquids so trapped. This surface roughness of the edge 21 is provided by roughening of the part of the mould which moulds this edge 21.This surface roughening can be carried out in a number of ways, but the preferred method is to blast the relevant surface of the mould with sand particles in a flow of gas, typically air (so called "vapour blasting").

The invention is not restricted to the details of the foregoing examples. For example in the elasticated sections 54,61, the "X's" may be replaced by, for example, open squares, "O's", "S's" or other shapes.

Referring now to the second embodiment of the invention illustrated in Figures 6 to 8, there is illustrated a strap and clip which may be attached to a mask of the type shown in Figures 1 to 5.

In this case, however, the elasticated sections 61 and 54 are formed of a wide band 70 of material which is corrugated out of its plane. Thus, as is clear from Figure 7, the band 70, where it provides an elasticated section, is moulded into a serpentine form which includes some portions 71 extending transversely of the plane of the band 70 and some portions 72 extending generally longitudinally parallel to the plane of the band 70 As before, it will be understood that, the material of the band 70 is of a flexible but non-elastic nature and the elastication is provided by the transverse portions 71 pivoting or rotating so as to be less transverse to the plane of the band 70.

Another change from the first embodiment of the invention is that the spaced male parts are not provided by spheres but by cylindrical members 53. The sockets 26 are formed of a complementary shape, the two sockets being arranged spaced from one another and end to end but at an angle with respect to one another as is clear from Figure Figure 8 shows a cross section on the line A-A of Figure 6 showing the cross-sectional shape of the socket 26.

Claims

1. A strap moulded of a substantially non-elastic material, the strap including at least one transversely disposed link extending transversely to the length of the strap whereby said at least one transversely extending link may flex to provide an elastic extension of the length of the strap.

2. A strap as claimed in claim 1, moulded of nonelastic polyvinylchloride.

3. A strap as claimed in claim 1 or 2 in which the strap includes a portion formed of linked X sections, the ends of the lengths of which are joined together.

4. A strap as claimed in claim 1 or claim 2 in which at least a portion of the strap comprises a wide band, part of which is corregated out of its claim so as to provide a serpentine form which includes portions extending transversely of the plain of the band.

5. A strap as claimed in any of claims 1 to 4 in two parts, one end of one part including a plurality of spaced male parts, and one end of the other part including one or more female parts, selective engagement of the male parts with the one or more female parts providing a variable length of the combined two parts of said strap.

6. A strap as claimed in claim 5 in which the male parts comprise spheres.

7. A strap as claimed in claim 5 in which the male parts comprise generally cylindrical members.

8. A strap as claimed in any of claims 5 to 7 in which the female part comprises one or - more shaped slots formed between two flexible wall portions.

9. A mask for application to a person's face for applying gas or a nebulized liquid/gas mixture thereto, said mask including a strap for passing behind the head and for retaining said mask in engagement with the person's face, said strap being in accordance with any of claims 1 to 8.

10. A mask according to claim 9 in which the edge of the mask, which in use, abuts the person s face, incorporates a surface with sufficient roughness to prevent the trapping of liquid between the mask and the face and/or to allow release of any liquid so trapped.

11. A mask as claimed in claim 10 in which said roughened edge of the mask is formed by moulding in a portion of a mould the surface of which has been roughened by means of blasting with grit material.