US 2540567 A
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Description (OCR text may contain errors)
Feb. 6, 1951 v, BENNETT 2,5; 40,567
v RESPIRATORY FACIAL MASK Filed May 3, 1948 3 Sheets-Sheet 1 Feb. 6, 1951 Filed May .3, 1948 V. R. BENNETT RESPIRATORY FACIAL MASK 5 Sheets-Sheet 2 Imventor,
(Ittorneg Feb. 6, 1951 v. R. BENNETT RESPIRATORY mom. MASK 3 Sheets-Sheet 5 Filed May 5, 1948 r O t n e D n 3 (Ittomeg Patented Feb. 6,1951
RESPIRATORY FACIAL MASK V. Ray Bennett, Los Angeles, Calif.
Application May 3, 1948, Serial No. 24,801
11 Claims. (Cl. 128-146) This invention relates to facial masks for respiratory use of the type employed clinically, industrially, in high altitude aviation, and other uses wherein air or a gas such as oxygen is supplied to a subjects respiratory system, and has as an object the provision of an improved type of mask suitable generally for such uses, and particularly adapted for use in hospitals and clinics.
Under many conditions it is essential to sup ply air or a gas mixture to a subject by either of'two optional methods: viz. by a tube entering the subjects mouth, or a mask or face piece applied either over the nose or over the mouth and nose. Recent developments have demonstrated that the'conventional use of a mouth tube and nose clip in conducting basal metabolism tests is conducive to serious error, presumably'resulting from both the actual physical discomfort caused by the apparatus, and by the psychological effect and nervous tension which are unavoidably produced in the patient by being required to breathe in such an unnatural manner, and which seriously interfere with the preservation of the requisite state of complete mental and physical relaxation on the part of the patient. On the other hand, the nasal and the oral-nasal masks now in general use are frequently uncomfortable to the subject, and usually do not insure a gas-tight seal. So serious is this situation that occasionally a subject will not tolerate the use of a mask even though a definite need for the use of a mask is fully realized.
The need for a comfortable, and yet tightly fitting mask is particularly pressing in cases involving pressure breathing, such as encountered in resuscitation, high altitude flying, and in positive and intermittent positive pressure breathing now being used clinically in oxygen therapy and in the treatment of pulmonary edema, asthma, cardiac conditions, and other types of respiratory depression or failure.
The combination of-nose clip and mouth tube have been generally used for the purpose of oxygen administration, particularly in connection with basal metabolism tests, presumably because of the difliculty of designing a small mask which would just cover the nose and mouth of asubject and which would seal'against the faces of subjects of widely varying facial characteristics. The problems presented by high nasal bridges as contrasted with flat noses, by prominent cheek bones and sunken cheeks, by prognathous and retracted jaws, have impeded the attempts to design a mask for general use which would be comfortable to the subject as Well as clinically satisfactory to the physician.
It is accordingly an object of my present invention to provide a mask covering only the nose and mouth of the subject'and the immediately surrounding facial area, which will provide a tight seal against internal pressure and yet which is so designed that it presses against the face of the wearer with substantially equal pressure throughout its entire area of contact. It is the resultant absence of localized pressure that contributes in the greatest measure to the absence of discomfort to the wearer, and which therefore is one of the outstanding characteristics of the mask of the present invention.
Another object of the present invention is p to provide a mask characterized by evenly distributed and therefore more comfortable pressure against the face, as indicated, and yet which is capable of developing a seal sufficiently dependable, to prevent the escape of gas from within the mask even when pressure considerably in excess of atmospheric is maintained therein.
Another object of the invention is to provide a mask suitable for pressure breathing and other respiratory uses, and which is separable into constituent parts for cleansing and sterilization or for replacement of worn parts, and thus made still more readily adaptable to hospital, clinical, and industrial uses, and whichmay easily and quickly be reassembled.
Still another object of the invention is to provide a mask for respiratory use which will leave the mouth and nose not only free of obstructions but visible from the exterior of the mask.
A further object of the. invention is to provide a mask of the character described, having a very small dead-air space and thereby minimizing the volume of gas to be rebre'athed.
Yet another object of the invention is to provide in a mask for respiratory use a self-sealing portion which may be used to receive supplementary service tubes and to serve as a safety relief valve for releasing excessive internal pressure when not in use as a tube adaptor.
Another object of the invention is to provide a respiratory mask having an outlet adapter designed to permit easy and rapid interchangeability of any desired outlet connector for any accessory equipment.
A further object of the invention is to provide a mask for respiratory use which is of very light weight so as to be comfortable to the subject and yet is durable and rugged, particularly in those parts which receive tubes or connectors externally and so are subject to strain and to wear.
This invent on possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of the preferred form of my invention which is illustrated in the drawings accompanying and forming part of the specification. It is to be understood that I do not limit myself to the showing made bythe said-drawings and description, as I may adopt variations of the preferred forms within the scope of my invention as set forth in the claims.
To the end of accomplishing these objects, I have made use of a relatively small face piece which may be made of such material as thin transparent plastic, molded to the general contours of selected areas of the human face and sufliciently rigid to form a base to which may be secured such accessories as a head harness, an outlet adapter, auxiliary ports if desired, and an inflatable pad, generally known as a cuff and yet sufiiciently flexible to aid substantially in assuming the general contour of the facial areas toward which it is pressed by the head harness. The cuff forms a soft cushion seal between the face piece and the face of a subject, conforming to facial ridges and depressions to which the plate cannot conform, and contains a soft resilient inner pad to assist it in this function, as will be set forth in greater detail in the following description based upon the drawings.
Referring to the drawings:
Figure 1 is a side elevational view of a mask embodying the principles of my invention, shown with a preferred form of head harness and in operative position on a subjects head.
Figure 2 is a frontal view of the mask shown in Figure l, with the outlet adaptor shown in section.
Figure 3 is a view similar to Figure l, but with the head harness and other details omitted, and
the mask shown in phantom lines to illustrate the small interior dead-air space.
Figure 4 is a frontal view similar to Figure 2, and also with details omitted, and with the mask shown in phantom lines and illustrating the areas of contact between the mask and the subjects face.
Figure 5 is a frontal View, partly in section, and on an enlarged scale, of a mask modified to include added features of auxiliary ports, the plane of section being indicated by the line 5-5 of Figure 6.
Figure 6 is a medial, vertical sectional view taken on the line 6-6 of Figure 5, with the direction of view as indicated.
Figure '7 is a transverse sectional view, the plane of section being indicated by the line 'l-l of Figure 5, with the direction of view as indi cated.
Figure 8 is an enlarged sectional view of one of the auxiliary ports, showing also a supplementary tube inserted therein.
Figure 9 is a further enlarged sectional view illustrative of the means for attaching the inflatable cuff to the face piece, the plane of section being indicated by the line 99 of Figure 5.
Figure 10 is a sectional view on an enlarged scale of means for attaching a head harness to the mask, the plane of section being indicated by the line ill-4!! of Figure 5.
Figure 11 is a sectional view of the outlet adapter of the mask, illustrating the method of securing thereto one type of outlet connection.
Figure 12 is a view similar to Figure 11, showing another type of outlet connection secured to the outlet adapter.
Specifically describing that embodiment of my invention which is illustrated in Figures 1 to 4, my improved mask comprises a face piece or plate [5 of such size and configuration as to extend from the bridge of a subjects nose and from the cheek bones below the eyes downwardly to the chin and to cover by lateral extension th frontal plane of the face, i. e., substantially that portion of the face below the cheek bones and forwardly of lines drawn vertically from the outer corners of the eyes. The lateral margins l6 are curved outwardly and rearwardly to define cheek pieces ll overlying the fleshy and soft portions of the cheeks from the cheek bones to the lower jaw, and curve forwardly to unite in a chin piece l8 and in a nasal ridge 9. The chin piece l8 and nasal ridge l9 extend forwardly to accommodate the nose and lips, forming a forward protuberance 20 provided with an orifice 2i substantially at its foremost portion.
The plate i5 is preferably formed of transparent sheet plastic material which may be molded to the form above described, and which has the qualities of hardness and limited flexibility. When so molded, a thin plastic plate will have negligible flexibility along horizontal lines, due to the channeling or reinforcing provided by the protuberance 29 and nasal ridge l9, but will be moderately flexible along vertical lines so that the cheek pieces I! may be bent forwardly or rearwardly to a material extent and thereby made to conform more accurately to wide or to narrow facial structures.
To provide a seal between the plate l5 and theface of the subject, a hollow tubular cuif 23 is provided, of generally toroidal form, so shaped as to underlie the peripheral edge of the plate it. In cross section taken in any plane extending radially with respect to the toroidal or annular form of the cuff, it is of generally flattened elliptic cross section; and it is preferably formed of soft rubber material capable of easy deformation when subjected to either internal or external stress. It is provided with an inflation tube 24, preferably in the region of the chin, which may be closed by a plug or stopper 25, so that the pressure of air or gas entrapped therein may be varied at will although, in this connection, it should be explained that under most circum stances of use, the cuif is not actually inflated otherwise than to the extent of entrapping the air which is contained within the cuff in its molded, elliptic form. This has been found to be the optimum pressure forthe gas within the cuff to permit ready displacement of gas from a portion of the cuff where its side walls are deflected inwards to cause another portion or other portions to be bulged outwardly by the consequent increased internal pressure. It is readily apparent, therefore, that the soft, highly flexible material of which the cuff is made, and the low pressure, approximately that of the ambient atmosphere, of the gas entrapped within the cuff cooperate to present a highly cushioned cuff, one portion of which may readily be pressed inwards where a protruding portion of a facial contour makes contact therewith, with the immediate result that other portions of the cuff are pressed outwards as an aid in fitting into depressions in the facial contour.
Small rubber plugs or buttons 26 are cemented or vulcanized to the cuff 23 at spaced points thereon, each of said buttons bearing a still smaller pull tab 21. The plate 15 has a plurality of holes 28 corresponding in position to the buttons '26 and of slightly smaller diameter. The cuff 23 may be readily attached to the plate 55 by aligning the buttons 26 with the corresponding holes 28 so that the pull tabs 27 extend through the holes, and by then pulling the rubber buttons by their tabs into the holes, in which they are held by compression. The compressive engage- 5. merit ofthe buttons zen: theholesi-28; WhilEThUld-r ing theicuff 2.3 to the plate lib during: ordinary usage, yet permits ready separation: of the plate. and the-cuff when it is :desired" toremove the cuff forlcle'an'ing-or forreplacemnt. "Oneof theholes 28 and the corresponding button zit-are preferably 'disposed' at "the nasal ridge? l8 to cause the cuff 2.3 to followithe contour-of the plate? l5closely at that point.
. The cuff 23 not' only is inflatable but also con tains and is supported internally by a; resilient. cushion 39., preferably of spongerubber.' The cushiDn 353 is-not continuous butwextendsacross the chin portion of the mask withincthe cufi fi, and its end portions extend upwardly withinithe cuff and' preferably terminate adjacentto the nasal ridge l9 so as'to leave a short-gapdijl? (see Figure 5), whereby'the portion of the-cuffwhi'ch crosses'the bridge ofrthesu-bjects-nose is devoid of internal support exceptfor pneumatic-pressure.
The cushion- 30 isnot attached to the euff2'3, but is merely loosely enveloped thereby. Preferably it is similarin cross section to the interionof the cuff but is slightly smaller-so that it-does not exert any expandingpressure thereupon. =In-: stead, it merelydefinestheminimum thickness which the cuff may assumeyand 'even in so -defining the cufis minimum thickness, it-lperforms this function resiliently because of the inherent cushionelike characteristic of-the sponge rubber of which it is made Consequently, one-of the principal functions of the-cushion-tfl ;is;to avoid complete collapse of the hollow cuff as might be occasioned if insufiicient pressure were maintained withinthe cuff, or if a personhaving unusually sharp features were being served. Other wise, the relatively sharp. edge of the face piece might be permitted to.press,-in. one or more locations, directly against the subjectsface, cushioned onlyby two thicknesses of the very-thin material of which the, cuff f23.is composed, 'andlthus be the source of irritationor actual physicaldiscomfort during long periods. ofuse.
The flattened elliptic capsule shape, of'the cuifisv transverse sectionisof especial significance because it results in presenting a, flat. orsubst'antially-flat surface in thatportion of the cuff which makes contact with the subjects face. Beingflat,
or substantially so, this area is much more easily deformed. For. example, a portion ofthe' cuff bearing against. a subjectfs cheek'bone or other protuberance of the face'will be more' readily pressed inwards because this area of the cuifis flat, than would be the. case if it were of circular cross,section.- Further, they g'as entrapped within the cuff and displaced by the inward'pressure. thus 'flat face-engaging wall to be deformed-and thus I enabling it to be" pressed into any-hollows of the facial contourwith. greater: effectiveness: because of its flat. characteristic.- in other words, by presenting a flat or substantially flat area ofcontact to the subjectsfaca-the cuff portion of the mask of the present invention is enabled to compensate for differentiation of'the. facial characteristics of yarious subjects m'uchmorereadily 'than'w'ere the cuff of trulycircular cross. section. I
Another detail which aidslmateria'ily in .carrying out these'sar'ne purposes'existsin the'pro portionate size'seof; the cushion; '3 0-- andtheint'erior of the hollow" cuff; The'former; is-materially narrowerthan the, latter; hence when the flatatopand' bottom surfacesof the cuff 'move outwardly, as when one of'them is being bulged downwardsinto a. facial cavity, the side edgesof thefcuff. are 'free to draw inwards, which would not be 'the case if'the cushion-corresponded in. widthto th interior of they cuff. r
r The plate' l fi and cuff 23 may beheld against a'subjects faceby a suitable head harness 33, an example of which is illustratedin Figures 1 and 2.- As therein shown, basal and occipital head straps $43 and 35 are attached to the plate iE-and'are-connected by other straps 36 across thetop of the skull-and forwardly and rearwardly ofthe subjects ears. It will be understood that other arrangements of harness straps be used and that the mask may be held against the subjects face by means. other than a'harness. The basal head strap 3 and "0c.- cipital head strap 35*are preferably attached." to the plate i5 by studs 3?, engageable selectively ii -holes .38 in the straps. The studs 31, ofwhich an example is shown in Figure 10, may be knobs, secured in the plate it by spun'flanges 3 9 on the innerside thereof and provided with bulbous headset. These are preferably disposed slightly inwardly from the margins of the "plate 15in the area-supported by the cuff 23 so that the straps 3i=and=35bear against the margins of the. plate when" under tension and tend to pull the plate against-the cuff and to pull the cuff'against the face. If the studstl are placed. too-centrally in the plate IS, the straps tend to flatten the plate and-cause leakage along the-cheek margins and the outer edges of the plate are uns'upport'ed. Moreover, by placing the studs 31 closely adjacentthe. edges of the plate i5, full advantage is taken of the plates inherent flexibility; permitting the. tension of the harness straps to flex the plate and thus. press the cuff more securely into thehollows ofthe facial contour.
The orifice'zl, as illustrated in Figure 11, is providedwith an adapter 42 which has ajmale r threadedportion 33 extending outwardly through the-.o'ififlceand a flange Q5 whichmay be sealed against the inner side of the plate 15 as by a gasket 25. A preferred means, for attaching a gasv supply tube, such as the chimney 360f conventional. 'anesthetizing apparatus (not shown) tothe adaptertlcomprises a ferrule s threadedlyengaging the adapter 42 and'havin'g a shoulder' e 'whieh abutsthe plate i5 so as to com- "pi-'ess'Tthe gasket '65 between the plate [5 and the flange G 4 of the adapter. Theferrule' ll" has at'aperedouter surface over which the coni' entionally tapered end 58 of the chimney 46 maybe-fo ced "The "adapter s2 is, in both of the above-deslcrib'edinstances, somewhat smaller in diametferthan 'theo'rifice it through which itiextends,
thus permitting an end portion 58 of'the ferrule .iiliorelbow' 5,2 to extend inwardly through the o'ri'fi'ce 2-! into contaotwith the gasket 55. This is-desirable in order to relievethe margin of the porificeof somecompressive stress. As hitherto stated, the plate it may bend sli htly about't'he 7 *be sct up' in the plate i fi tendi'ng to -crack:it; asit is preferably quite thin for the sake of lightness. By applying a portion of the compressive force directly to the gasket 65, the portion of the compressive force applied indirectly to the gasket through the plate i is diminished.
Some uses to which the mask of my invention is frequently put are facilitated by an elbow rather than the straight connector of Figure 11. For this purpose, I have provided a tubular rubber elbow 52 which, as illustrated in Figure 12, avoids the necessity of using any adapter since it is releasably and yet securely attached directly to the peripheral edge 53 of the orifice 2! which seats within a circumferential groove e in the outer surface of the elbow 52 adj acent the end 55 thereof which engages the plate i5. A radially extending flange 55 encircling the end 55 seats against the inner face of the plate l5, and preferably the diameter of the flange 56 is somewhat greater than that of the tube on the opposite side of its groove 54, thus enhancing the security with which the edge 53 is retained within the groove. Preferably a split metal ring 5? is disposed inside the end 55 of the elbow, this ring being so dimensioned that it exerts resilient outward pressure upon the end of the elbow, ending to expand the latter, and thus insurin amply strong mechanical connection as well as dependable gas-tight seal between the elbow 52 and the face piece 5. The elbow 52 can be removed easily from the face piece, however, simply by first withdrawing the ring 51 from within the end of the elbow, and thus collapsing the end 55 sufficiently to enable the flange 56 to pass freely through the orifice 2| of the face piece.
As it is frequently desirable in clinical use to apply surgical instruments or aspiration tubes to a subjects nose or mouth while the mask is in operative position. on the subjects face, auxiliary ports are preferably provided for such instruments. One such port is shown at 6B in Figures 5 an '7, and comprises a rubber cup 6! which may be inserted into the mask through an orifice 62 in the plate l5 and which has double flanges 63 for gripping the margin of the orifice 62 and lips 64 which are normally held closed by their own inherent resiliency and by pressure prevailing within the mask, but which may be spread by a needle-like instrument.
Another auxiliary port, suitable for insertion of Miller-Abbott tubes into the patients nose or for insertion of Levine stomach aspirator tubes, or tubes of similar purport, is shown at 2'6 in Figures 5 and 7, and in detail in Figure 8. In this form of port, a rubber cup 1! is attached to the margin of an orifice '52 in the plate 55 by double flanges E3 and extends outwardly therefrom The cup H has a relatively large communicating passage l adapted to receive a tube E5 of the Miller- Abbott or Levine type, with a grip sufliciently strong to constitute a pneumatic seal. A plug 16 is held by a spring ll so as normally to close the passage i l and may be raised from the passage against the resistance of the sprin to permit insertion of a tube. Or, when no tube is in use, the plug it may be raised from sealing position in the passage 14 by an excess of pressure within the mask sufficient to counteract the force of the spring ll. Thus the port it constitutes a safety relief valve for excess pressure when a patient is not being tubed.
The mask hereinabove described may be used in conjunction with any standard apparatus for supplying air or gas through the orifice 2!; or various types of filter or dust cannisters may be attached. Such apparatus usually has valve means disposed in close proximity to the mask for alternately admitting gas to the mask and permitting the exhalation of breathed gases to the ambient atmosphere, or to a C02 absorber. The dead-air space of the mask, that is, the space within the mask which may contain breathed gases, is limited to the small mask cavity within the forward protuberance 20, which is largely occupied by the subjects nose and lips and which is bounded laterally by the inner margin of the cuff 23. The subject, if conscious, may speak as his mouth is not occupied by a breathing tube, and his own nose and mouth are at all times visible to attendants.
When the cuff 23 is inflated by means of the inflation tube 24, it will seal the mask comfortably on any facial type, with very few exceptions, even against mask pressures as high as twentyflve to thirty centimeters of water column. Because of the cushion 39, the plate i5 is held at all points out of contact with the facial tissues regardless of any local under-inflation of the cuff 23. A focal point on many types of mask for both leakage and discomfort is at the bridge of the nose, but the ends of the cushion 39 extend upwardly on the sides of the nose in a manner raising the nasal ridge 19 from the nose. The gap 3! between the ends of the cushion 36 leaves the cuif 23 free to conform by internal pneumatic pressure to any shape of nose so that it neither presses objectionably upon a high bridge or fails to seal against a flat one.
For cleaning or sterilization, or for replacement, the cuff 23 may be quickly removed from the plate I5 by simply pulling the plugs 25 from the holes 28, and may be nearly as quickly replaced by pulling the plugs 26 into the holes 28 by means of the tabs 21. This feature, as well as the adaptability of the mask to various types of gas conduits by means of the adapter 42 and the receptivity of the mask to surgical instruments through the auxiliary ports 6!] and E0, causes the mask to possess definite advantages in such clinical uses as pressure-breathing therapy, general oxygen therapy, inhalation therapy and resuscitation, general anesthesia, and metabolism studies.
1. A facial mask for respiratory use, comprising a face plate of transparent sheet material molded to conform marginally generally to the frontal contours of the human face and having a nasal ridge terminating in a frontal protuberance and having a substantially central oriflee in the forepart of said frontal protuberance, an inflatable sealing cufl, generally flattened elliptic in cross section and adapted to underlie the margins of said plate, a pad of resilient material loosely enveloped by said cuff and termmating at each side of said nasal ridge so as to leave a portion of said cuff traversing said nasal ridge supported internally solely by pneumatic pressure, means for attaching said cuff to said plate, and means disposed in said central orifice for attaching a conduit thereto.
2. A facial mask for respiratory use, comprising a face plate having a frontal protuberance adapted to enclose the nose and mouth, and marginally overlying the cheek bones and chin, an inflatable tubular sealing cuff secured to and underlying the margins of said plate, said cuff being generally elliptic in section with the major axis of said section extending substantially ra- ":5 dially of said mask whereby a relatively flat surface of said cuff is presented to the wearers face, and a pad disposed within the hollow interior of said cuff, said pad being generally elliptic in section with the major axis substantially in alignment with that of said cuffs section, and said major axis of said pads section being materially shorter than said major axis of said cuffs section, whereby space remains between at least one lateral edge of said pad and the interior face of the corresponding portion of said cuff.
3. A facial mask for respiratory use, comprisin a transparent face plate molded to conform marginally generally to the frontal contours of the human face, a sealing cuff generally elliptic in section and adapted to underlie the margins 'of said plate, a pad loosely enveloped by said cuff, means disposed in the forepart of said plate for attaching aconduit to said plate in communication with the interior of said mask, and auxiliary port means in said plate for admis* sion of instruments to the interior of said mask, said port means including a spring and a plug held thereby to yieldably seal said port means against egress of gas.
4. A facial mask for respiratory use, compris ing a face plate adapted to cover the nose and mouth and marginally overlying the fleshy parts of the cheeks, the bridge of the nose, and the chin, an inflatable sealing cuff of tubular flexible airtight material, generally elliptic in section and adapted to underlie the margins of said plate, a pad loosely enveloped by said cuff and providing internal support therefor, a plurality of rubber plugs on said cufi, said plate having holes therein disposed correspondingly to said plugs and adapted to compressively receive said plugs so as to detachably secure said cuff to said plate, each of said plugs terminating in a tab smaller than the hole corresponding thereto whereby said plug may be pulled into compressed engagement with said hole, and means disposed in the forepart of said plate for attaching a conduit to said late in communication with the interior of said mask.
5. In a facial mask of the character described, the combination of a face plate of hard material, an inflatable hollow cuff secured to and underlying a portion of said plate, said cufi being of flattened elliptic cross section and presenting a substantially flat face-engaging surface readily deformed to compensate for irregularities and a pad of resilient material within said cuff, said pad substantially defining the minimum thickness of said cuif but being substantially narrower than the interior of said cuff measured in lines parallel to said face plate whereby the lateral edges of a section of said cuff are free to move towards each other and said face-engaging surface at said section of said cuff is free to move into a depression in the face of the wearer without interference by said pad.
6. In a facial mask of the character described,
ment and having a plug for said passage and a 10 spring yieldably holding said plug in sealing engagement with the outer end of said passage.
8. In a facial mask of the character described, the combination of a face plate of hard material capable of limited flexure and having an orifice for the admission of gas to the interior of said mask, an adapter extending through said orifice for attaching a conduit thereto, said adapter having an outwardly extending and externally threaded portion and a flange on that portion disposed within said mask, and a gasket disposed betweensaid flange and said plate, said orifice being of greater diameter than said outwardly extending portion so as to permit a member threaded to said outwardly extending portion to come into contact with said gasket.
9. A facial mask for respiratory use, comprising a face plate adapted to cover the nose and mouth and marginally overlying the fleshy parts of the cheeks, the bridge of the nose, and the chin, an inflatable sealing cuff of tubular flexible airtight material adapted to underlie the margins of said plate, a plurality of rubber plugs on said cufi, said plate having holes therein disposed correspondingly to said plugs and adapted to compressively receive said plugs so as to detachably secure said'cuff to said plate, each of said plugs, terminating in a tab smaller than the hole corresponding thereto whereby said plug may be pulled into compressed engagement with said hole, and means disposed in the forepart of said plate for attaching a conduit to said plate in communication with the interior of said mask.
10. In a facial mask of the character described, the combination of a face plate, a hollow pneumatic cushion of yieldable material carried by said plate in position to lie between said plate and the wearers face when said mask is in use, the wall of said cushion nearest the wearer's face being substantially fiat and thereby being adapted to be bulged in localized areas into a facial depression, and a pad disposed within said cushion, at least one of the transverse dimensions of said pad in at least one section thereof being shorter than the corresponding interior dimension of said cushion whereby at least one wall of said cushion is free to move inwardly at said section in compensation for outward bulging of another wall of said cushion at said same section.
11. In a facial mask of the character described, the combination of a face plate, a hollow pneumatic cushion of yieldable material carried by said plate in position to lie between said plate and the wearers face when said mask is in use, and a pad disposed within such cushion, at least one of the transverse dimensions of said pad in at least one section thereof being shorter than the corresponding interior dimension of said cushion whereby at least one wa l of said cushion is fr e to move inwardly at said section in compensation for outward bulging of another wall of said cushion at said same section.
V. RAY BENNETT.
REFERENCES CITED The followin references are of record in the flle of this patent:
UNITED STATES PATENTS Num er I Name Date 2,254,854 OConnell Sept. 2, 1941 FOREIGN PATENTS Number Country Date 458,403 Great Britain