GB2329128A

GB2329128A - Nose clip for a respiratory mask

Info

Publication number: GB2329128A
Application number: GB9719444A
Authority: GB
Inventors: Chris Henderson; John Bryant; Nick Gloag
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1997-09-15
Filing date: 1997-09-15
Publication date: 1999-03-17
Also published as: GB9719444D0

Abstract

A respiratory mask (1) which may be of the fold-flat or the moulded type, includes a nose clip (9) in the form of a flattened strip (11) of malleable material, the end regions (12) of which are twisted to displace the upper edge of the strip, in those regions, in the forwards direction. The central region (13) of the strip may be curved in the forwards direction.

Description

Nose clip for a respiratory mask The present invention relates to respiratory masks and is concerned, in particular, with a nose clip which may be included in a respiratory mask to improve the fit of the mask to the face of the wearer.

Respiratory masks are worn when it is necessary or desirable to protect the wearer against inhaling airborne contaminants such as fumes, dust, bacteria etc. and/or to protect others from being exposed to contaminants exhaled by the wearer. A respiratory mask should be a snug fit to the face of the wearer so that air entering/leaving the interior of the mask does not by-pass the filtering action of the mask. The nose region of the face can be one of the most difficult areas in which to achieve the required degree of fit, especially in the case of disposable masks, and a recognized way of dealing with that problem is to provide a mask with some form of stiffening device (or nose clip) for holding the mask to the wearer's nose. Nose clips are used in both moulded and fold-flat respiratory masks: moulded masks are preformed into a desired face-fitting configuration (typically a cup shape) and generally retain that configuration during use whereas fold flat masks are packed flat but are formed with seams, pleats and/or folds which enable them to be opened out into a configuration in which they can be placed over the nose and mouth of the wearer. In both types of mask, the nose clips are conventionally in the form of a malleable strip (for example, a strip of aluminium) which the wearer can press against his/her nose when the mask is put on. Nose clips of that type function well in terms of enabling a mask to be moulded to the contours of the face but can, in some cases, cause discomfort to the wearer.

Fold-flat respiratory masks which include, in one case, a stiffening device and, in the other case, a deformable metal strip to allow moulding of the mask around the wearer's nose are described in US-A-4 920 960 and 3 603 315. US-AX 600 002 and GB-A-2 103 491 describe fold-flat masks each provided with a malleable strip in the shape of a chevron to facilitate fitting and maintaining fit of the mask over the nose.

A moulded respirator with a nose clip is described in US-A-5 307 796. In that case, the nose clip is a pliable dead-soft band of metal.

US-A-5 558 089 describes a respirator nose clip which is shaped to provide a good fit to the wearer's face without substantially restricting flow through the nasal passages of the wearer.

The present invention is concerned with providing a nose clip which, in a respiratory mask, will provide an enhanced degree of comfort to the wearer while maintaining a good fit to the wearer's face in the nose region.

The present invention provides a nose clip for use in a fold flat respiratory mask to assist in fitting the mask over a wearer's nose, the nose clip comprising: a flattened strip of malleable material, the strip having a forwardly-directed front surface, a rearwardly-directed back surface, and upper and lower edges; each end region of the strip being twisted to displace the upper edge in the forwards direction.

The invention also provides a nose clip for use in a fold flat respiratory mask to assist in fitting the mask over a wearer's nose, the nose clip comprising: a flattened strip of malleable material having a length in the range of from 20 to 140 mm, the strip having a forwardly-directed front surface, a rearwardly-directed back surface, and upper and lower edges; wherein a length in the range of from 5 to 35 mm at each end of the strip is twisted to displace the upper edge in the forwards direction.

When a clip in accordance with the invention is included in a respiratory mask, it is located to extend over the bridge of a wearer's nose with the upper edge ofthe strip directed towards the upper edge of the mask and the front surface directed away from the wearer's face. The mask is fitted by placing the mask over the nose and mouth of a wearer, and deforming the nose clip at least in the central region of the strip to achieve a snug fit ofthe mask over the wearer's nose.

By way of example only, embodiments of the invention will be described with reference to the accompanying drawings, in which: Figs. 1 and 2 are front views of a fold-flat respiratory mask in, respectively, a folded and an unfolded condition; Fig. 3 shows the mask of Figs. 1 and 2 in use on a wearer's face; Fig. 4 shows a modified form of the mask; Fig. 5 is a front plan view of the nose clip of the masks of Figs. 1 to 4; Fig. 6 is a view from below of the nose clip of Fig. 5; Fig. 7 is an enlarged view, from one end, of the nose clip of Fig. 5; and Fig. 8(A and B) illustrates alternative cross-sections for the nose clip.

The fold-flat respiratory mask 1 (shown in Fig. 1 in its folded, or storage, condition and Fig. 2 in its ready-for-use unfolded condition) comprises a central part 2 of generally elliptical shape, and upper and lower parts 3, 4 bonded to the central part at bonds 5, 6 respectively. In the folded condition, the upper and lower parts 3, 4 are folded behind the central part 2 and are, accordingly, not visible in Fig. 1. In the unfolded condition, when the parts 3 and 4 are opened out, the mask has a generally cup-shaped form suitable for placing over the nose and mouth of a wearer, as shown in Fig. 3, when respiratory protection is required.

The parts 2, 3 and 4 of the mask are formed from multiple layers of material including at least one layer of filter material. A headband 7, only part of which is shown in Figs. 1 and 2, is attached to the mask at each end of the central part to hold the mask in place on the wearer's face. In use in its unfolded condition (Fig. 3), the periphery 8 of the mask is a snug fit against the face of the wearer so that air entering or leaving the mask will pass through the layer(s) of filter material. A nose clip 9, described in greater detail below, is included in the upper part 3 of the mask to enable a good fit to be achieved in the nose region of the wearer's face.

A modified version of the mask 1, shown in Fig. 4, incorporates an exhalation valve 10 mounted in the central part 2.

Respiratory masks ofthe type shown in Figs. 1 to 4 are described in WO-A96/28217, to which reference may be made for further information regarding the general construction of the masks. As described in WO-A-96/28217, the shape of the masks in the folded condition may vary substantially from the generally elliptical shape shown in Fig. 1.

The nose clip 9 of the respiratory mask 1 is shown, greatly enlarged, in Figs. 5 to 7.

Fig. 5 is a plan view of the clip 9 as seen from the front (i.e. as it would be seen from the outside of a mask); Fig. 6 is a side view of the clip as seen from below in Fig. 5; and Fig. 7 is a view, even further enlarged, from one end as indicated by the arrow VII in Fig. 6. The nose clip 9 is formed from a flat strip 11 of a malleable metal, for example aluminium or an aluminium alloy, bent to a configuration in which it has two twisted regions 12 (one at each end of the strip 11) and a central curved region 13.

The surfaces 14, 15 of the strip 11 form respectively the front and rear surfaces of the nose clip 9 when the latter is incorporated in the mask 1 (i.e. they are directed towards, respectively, the exterior and the interior of the mask), and the edges 16, 17 of the strip form respectively the upper and lower edges of the nose clip. Depending on the shape of the mask in which the nose clip is used and on the material from which the clip is formed, the undeformed strip 11 has a length in the range of from 20 to 140 mm (typically 75 to 105 mm), a width in the range of from 2 to 10 mm and a thickness in the range of from 0.4 to 2.0 mm (typically 0.4 to 1.1 mm). In one particular case, a nose clip for a respiratory mask as shown in Figs. 1 to 3 is made from aluminium of 99.7% purity (E.C. Grade 1070/1370) and has a length of about 90 mm, a width of 5 mm and a thickness of 0.9 mm.

The two twisted end regions 12 together take up about one third of the length ofthe strip 11 and the central curved region takes up substantially the remaining two thirds so that it extends over substantially the whole of the distance between the two end regions. Depending, however, on the shape of the mask in which the nose clip is used, the twisted end regions 12 could together occupy up to about one half of the length of the strip 11. Each half of the nose clip 10 is a mirror image of the other about a vertical central line across the clip.

Each of the end regions 12 is formed by twisting the adjacent end 12a of the strip 11 about the longitudinal central axis of the strip so that, over the length of the region 12, the upper edge 16 of the clip is displaced in the forwards direction (i.e. out of the plane of the paper in Fig. 5) and the lower edge 17 is displaced in the opposite direction. Depending on the length of the strip 11, the angle through which each end 12a is twisted is typically in the range of from 5O to 15 although it could be larger and, in some cases, even as large as 45". The position of the longitudinal central axis of the strip in the twisted end regions 12 remains unchanged from that of the longitudinal central axis of the undeformed strip.

The curved central region 13 of the clip extends forwards from the twisted end regions 12, as shown in Fig. 6, but the longitudinal central axis ofthe strip in this central region remains in the same plane perpendicular to the surfaces 14, 15 of the undeformed strip. The curve in the central region 13 is comparatively shallow: typically, it has a radius of about 10 cm which, in the case of a 90 mm long strip, serves to displace the mid point of the strip by about 3 mm in the forwards direction.

The nose clip 9 is positioned on the outside of the respiratory mask 1 adjacent the upper edge of the upper part 3, in a central position in which, in use, it will extend across the bridge of the wearer's nose. The nose clip may be secured to the mask by an adhesive, for example, a pressure sensitive adhesive or a liquid hot-melt adhesive.

Alternatively, the nose clip may be encased in the body of the respiratory mask or it may be held between the body and a fabric or foam that is mechanically or adhesively attached thereto. In a preferred embodiment, the nose clip 9 is positioned underneath a cover web on the outside ofthe upper part 3 of the mask and a foam piece (not shown) is disposed on the inside surface of the upper part, in alignment with the nose clip.

When the wearer dons the mask, the curve in the central region 13 of the nose clip 9 assists the wearer in positioning the mask centrally on his/her face, after which the wearer will conform the clip to fit to the face by bending the central region 13 as necessary to a shape that corresponds to that of the bridge of his/her nose. The twist that is present in the end regions 12 ofthe clip allows those regions ofthe clip to lie comparatively flat against the wearer's face in the areas in which the nose meets the cheeks but, if necessary, the degree of twist can be increased by the wearer.

In some cases, it may be possible to omit the curve in the central region 13 ofthe nose clip, particularly if some alternative means is employed to assist the wearer in initially positioning the mask on his/her face. Suitable alternative means include, for example, marking the mask and/or the nose clip to indicate the centre line.

Although the use of an aluminium strip 11 for the nose clip 9 is desirable because of the ease with which the clip can be formed by the wearer to achieve a good fit to the face, it should be understood that the clip can be formed from other materials including, for example, steel or a plastic coated/encased metal. When an aluminium strip is used, it is advantageously formed so that the neutral bending axis of the strip is displaced from a point mid-way between the two surfaces of the strip towards the front surface. In that way, the nose-clip will have a greater resistance to opening out once it has been fitted to the wearer's face. The displacement of the neutral axis can be achieved by, for example, subjecting the strip to a greater degree of workhardening on the front surface 14 than on the rear surface 15. The differential work hardening may, for example, be achieved simply by applying different degrees of pressure to the two sides of the aluminium strip I 1. If the strip 11 is stamped out of a flat sheet of aluminium, the differential work hardening may be effected during the subsequent handling of the strip. Alternatively, if the strip is formed by a rolling or an extrusion process, the differential work hardening may be effected during manufacture of the strip. Alternatively, a desirable displacement of the neutral axis may be achieved through the use of a strip which has a non-rectangular crosssection. The strip 11 may, for example, have a trapezoidal cross-section as shown in Fig. 8A or a substantially rectangular cross-section with ribs on one surface as shown in Fig. 8B: in either case, the neutral axis ofthe strip is displaced towards the surface 14, which is intended to be the front surface of the nose clip. It will be appreciated that a similar effect could be achieved using aluminium strips 11 with other crosssections.

Figs. 1 to 4 show a nose clip in accordance with the present invention in use in a particular form of fold-flat respiratory mask. The nose clip is not, however, restricted to use in that type of mask and could be used in other fold-flat masks or in moulded masks to facilitate the fitting ofthe mask to the face ofthe wearer.

Claims

1. A nose clip for use in a fold flat respiratory mask to assist in fitting the mask over a wearer's nose, the nose clip comprising: a flattened strip of malleable material, the strip having a forwardly-directed front surface, a rearwardly-directed back surface, and upper and lower edges; each end region of the strip being twisted to displace the upper edge in the forwards direction.

2. A nose clip as claimed in claim 1, in which each end region of the strip is twisted about the longitudinal central axis of the strip whereby the lower edge of the strip is displaced in the opposite direction to the upper edge.

3. A nose clip as claimed in claim 2, in which each end of the strip is twisted through an angle in the range of from 5 to 450.

4. A nose clip as claimed in claim 2 or claim 3, in which each end of the strip is twisted through an angle no greater than 15 .

5. A nose clip as claimed in any one of the preceding claims, in which the strip is twisted at each end over a length in the range of from 10 to 25% of the total length of the strip.

6. A nose clip as claimed in any one of the preceding claims, in which the strip is twisted at each end over a length of about 15% of the total length of the strip.

7. A nose clip as claimed in any one ofthe preceding claims, in which a central length ofthe strip is curved in the forwards direction.

8. A nose clip as claimed in claim 7, in which the said central length extends substantially between the twisted end regions of the strip.

9. A nose clip as claimed in claim 8, in which the curve in the central length of the strip is comparatively shallow and displaces the mid-point of the strip through a distance of about 6% of the distance between the twisted end regions of the strip.

10. A nose clip for use in a fold flat respiratory mask to assist in fitting the mask over a wearer's nose, the nose clip comprising: a flattened strip of malleable material having a length in the range of from 20 to 140 mm, the strip having a forwardly-directed front surface, a rearwardly-directed back surface, and upper and lower edges: wherein a length in the range of from 5 to 35 mm at each end of the strip is twisted to displace the upper edge in the forwards direction.

11. A nose clip as claimed in claim 10, in which each end of the strip is twisted through an angle in the range of from 5 to 45"

12. A nose clip as claimed in claim 10 or claim 11, in which a central length of the strip, extending substantially between the twisted end regions of the strip is curved it the forwards direction to displace the mid-point of the strip, through a distance no greater than 5 mm.

13. A nose clip as claimed in any one of claims 10 to 12, in which the strip has a width in the range of from 2 to 10 O mm and a thickness in the range of from 0.4 to 2.

mm.

14. A nose clip as claimed in any one of the preceding claims, in which the neutral bending axis of the strip is displaced towards the front surface of the strip whereby, following deformation around the nose of the wearer, the strip has a greater resistance to a bending action tending to move the ends of the strip in the forwards direction than to a bending action tending to move the ends of the strip in the rearwards direction.

15. A nose clip as claimed in claim 14, in which the cross-section of the strip is nonrectangular and is shaped so that the neutral bending axis of the strip is displaced towards the front surface of the strip.

16. A nose clip for a respiratory mask, substantially as described herein with reference to, and as illustrated by, Figs. 5 to 7 of the accompanying drawings.

17. A respiratory mask including a nose clip as claimed in any one of the preceding claims, the clip being located to extend over the bridge of a wearer's nose with the upper edge of the strip directed towards the upper edge of the mask and the front surface directed away from the wearer's face.

18. A respiratory mask as claimed in claim 17, in which the mask is formed from multiple layers of material and the nose clip is located between two of the layers.

19. A fold-flat respiratory mask, substantially as described herein with reference to, and as illustrated by, the accompanying drawings.

20. A method of fitting a respiratory mask of the type claimed in claim 17 or claim 18, including the step of placing the mask over the nose and mouth of a wearer, and deforming the nose clip at least in the central region of the strip to achieve a snug fit of the mask over the wearer's nose.

21. A method as claimed in claim 20, substantially as described herein.