US2241535A - Apparatus for delivering and permitting normal breathing of mixtures of gases - Google Patents

Description

May 13, 1941. w. M. BOOTHBY ETAL 2,241,535

APPARATUS FOR DELIVERING AND PERMIT TING NORMAL BREATHING 0F MIXTURES OF GASES Filed July 28, 1959 4 Sheets-Sheet 1 l A h Invfin'bors: W.M.Boo hb F1 i A H BuLbuuo'f n. V w.R.LoveLace.

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y 1941- H w. M. BOOTHBY ETAL 1,535

APPARATUS FOR DELIVERING AND PERMI'TTING NORMAL BREATHING OF MIXTURES OF GASES Filed July 28, 1959 4 Sheets-Sheet 2 Inventors. \N. M.BOOthbld A. H.BuLbuLLoLn.

W.R Love,Lace

Kttor ne y 1941- w. M. BOOTHBY ETAL 2,241,535

APPARATUS FOR DELIVERING AND PERMITTING NORMAL BREATHING 0F MIXTURES OF GASES Filed July 28, 1939 4 Sheets-Sheet 5 Inventor-s:

.n 9a mu u E 0U 53 MH WA \N. R. Lovelace. .Mfl

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May 13, 1941'. w. M. BOOTHBY ETAL 2,241,535

APPARATUS FOR DELIVERING AND PERMI'I'TING NORMAL BREATHING OF MIXTURES 0F GASES v Filed July 28, 1939 4 Sheets-Sheet 4 Inventor-s \MM.Booth.b5 A. H.Bul.louLLan. W. R.LoveLace. B

Patented May 13, 1941 APPARATUS FOR- DELIVERING AND PER.- IVIITTING NORMAL BREATHING OF MIX- TUBES F GAiSES Walter M. Boothby, Arthur H. Bulbulian, and William R. Lovelace, Rochester, Minn.

Application July 28, 1939, Serial No. 287,086

, 3 Claims.

Our invention relates to apparatus for delivering and permitting normal breathing of mixtures of gases, and has for its primary object to pro,- vide means for supplying such mixtures as for example 100 per cent oxygen mixed with the first and most oxygen-enriched portions of gases of exhalation, or oxygen mixed with desired proportions of air, with the utmost efiiciency in the use of oxygen, in combination with a mask adapted to be held positioned upon the face of a wearer in such a way as to be comfortable and permit normal breathing, the mask herein presented being a nasal mask to permit normal breathing through the nostrils in the usual way entirely unrestricted and to leave the mouth and eyes wholly unobstructed.

There are, under modern developments, certain well known conditions where it is desirable or essential to supply to individuals mixtures of gases to be breathed and particularly oxygen, either with or without added air. These conditions to be met, while roughly they may be put into two classes, are all essentially medical.

The first of these classes is in connection with the development of air transport and aviation, in which, owing to the desirability of flying at increasingly high altitudes, an inescapable need has arisen to supply added oxygen in proportions determined by elevation and consequent attenuation of the atmosphere. This need, not heretofore satisfactorily met, has greatly restricted the development of flying at high altitudes, which, except for difliculties of oxygen supply due to the wasteful use of oxygen brought about by unsatisfactory forms of apparatus, is generally recognized as a most desirable advance to be made. While in the ordinarily accepted sense, the supplying of oxygen to meet deficiency thereof in atmospheric air at high altitudes might not be regarded as medical, in fact it is medical, since it is obvious that not only failure to supply needed oxygen, but alsosupplying it in a manner to produce discomfort and irritation to the breather, cannot but lead to injurious effects, especially when the manner'of use is so wasteful and inefficient as not to give a satisfactory mixture.

The second set of conditions requiring addition of oxygen or other gases to the breathing supply may be regarded as purely medical, and yet the same elements of need of proper supply and of preventing discomfort and irritation to patients the result that many lives are unnecessarily lost. This class, particularly in relation to the addition of oxygen, comprises those medical cases where addition of oxygen to the breathing supply (or other gases) is resorted to to prolong life and enable recovery from pathological afllictions such as pneumonia and the like long known to be benefitted byoxygen administration. Here again it is of the utmost importance that the means for supplying the breathing mixture, including added oxygen, must be such as to avoid any interference with natural breathing and likewise to avoid discomfort or irritation to the patient in any appreciable degree. Heretofore, in such cases, addition of oxygen to the supply of air to be breathed has been effected by what is known as an oxygen tent. This is an appliance expensive in char acter, wasteful of costly oxygen, and available only in hospitals, generally of larger cities only, i

by the layman has heretofore existed.

It is well known that a provision of inhalation apparatus which will be economical in the used oxygen and which at the same time permits the administration of 100 per cent oxygen will open up a whole new field of oxygen therapy of great value in certain classes of cases, such as migraine of ananaethetist, not only desired mixtures of air and added oxygen, but, where indicated, per cent oxygen, and to embody in such inhalation device a nasal mask structure adapted to be held upon the face of a. wearer when either sitting -mixture of gases, as of oxygen and air or 100 per cent oxygen, such that the patient can wear the device and breathe while wearing it without appreciable discomfort or irritation of any sort and can breathe with substantially the same degree of ease and naturalness as he could, without any appliance, in the open air.

It is a further object of our invention to construct a nasal mask having means to hold it about over the nose of the wearer, with gas supply means to the chamber about the nose such that as the mask is held upon the face, no part of it or of the gas supply means can come above or obstruct the mouth of the wearer.

It is a further object of our invention to construct a nasal mask having a chamber surrounding the nose of the wearer and spaced from the openings of the nostrils and having means for supplying a gas mixture to said chamber, such that when the same is held upon the face of the wearer it will automatically seal the open side of the said chamber against the face and lip of the wearer, and be held in the sealing position without causing material discomfort or irritation to the wearer and which mask in. the formation of its chamber and sealing means shall be adapted in a single construction for men and anothercovered that the bony structure of human faces,

including the nose andthe parts about it, are in general remarkably similar, the difference in appearance of faces and noses being in general brought about by the soft parts covering the bony structure, there being of course, a characteristic difference between the bony structure of male faces and female faces. 0n the basis of this discovery we have been able to produce a nasal mask (and also an oronasal mask not here shown),

which, in a single construction for men and for women respectively, meets the requisite conditions of sealingthe nasal chamber against the face and nose ofthe wearer regardless of apparent facial and nasal external differences to be noted in diiferent wearers.

It is a further and highly important object of our inventionto construct a mask having a, nasal chamber adapted to sealagainst the face and nose of the wearer at its open side, wherein the chamber will provide just sufi'icient space at the front of the nose and. particularly below the outer ends of the nostrils and about the alae nasi, in combination with balanced outlet tubes communicating with said chamber, all of which will have the efiect of permitting normal breathing without any restriction or added efiort in accomplishing it, and always with no contact of any part of the mask with the alae nasi as they expand in respiration.

It is a further object of our invention to position the outlet tubes in curves extending inwardly upon the face of the wearer and, uniting ner so supporting the tubes and the connected rebreathing bag which is customarily employed as to prevent any displacement or tendency towards displacement of the parts forming the sealed nasal chamber.

Oxygen can be delivered at atmospheric pressure from storage tanks through suitable pressure reducing valve mechanism in the desired volume to be breathed. We have discovered, however, that if the oxygen is not delivered directly to the patientbut to a reservoir bag, which also preferably will be a rebreathing bag, wherein the oxygen flowing in during expiration is conserved and prevented from wasteful loss, and in connection with which it may be mixed with that part of exhaled .air richest in oxygen and most deficient in carobn dioxide, and also may or may not be mixed with atmospheric air, as desired or indicated, before being inhaled, more economical and satisfactory results will be obtained. Further such an arrangement is, if used with a mask which can be comfortably worn, admirably adapted to self-administration of 100 per cent oxygen for comparatively long periods of time, which, as above pointed out, may be of great benefit in remedying certain pathological conditions.

It is a further object of our invention therefore, to provide in conjunction with the aforesaid mask and outlet arrangement a reservoir rebreathing bag, preferably supported thereby, and to deliver the oxygen directly to the bottom of the reservoir while the same is supported from the mask construction, and to provide air inlet means to the passages and the rebreathing bag, which may be entirely closed off where 100 per cent oxygen is desired, whereby, in conjunction with the constantly infiowing. oxygen, exhalationswill distend the rebreathing bag and inhalations will draw into the lungs a mixture of oxygen and exhaled gas, or such a mixture with as much atmospheric air added thereto as may be desired. I

Since it is necessary to withdraw from the air being breathed a certain part of the carbon (11- oxide in the exhaled gases as they come from the lungs, and since the later parts of anexhalation will-always contain the larger percentages of carbon dioxide, just as the first parts of the exhalation contain the larger percentages of oxygen, it is a further object of our invention to provide a reservoir rebreathing bag having 2. volume when distended less than that of a full expiration, together with outlet means, the arrangehalation, while the later part of the exhalation,

including the gases most charged with carbon dioxide, will be caused to go to atmosphere.

It is a further object of our invention to provide, in conjunction with means connecting the reservoir rebreathing bag to the passages from the mask, an air inlet regulating device, whereby air in varying quantities from none at all, where the device is used for breathing per cent oxygen, to a maximum amount indicated or desired, may be admitted to the system and breathed in by the patient together with the mixture of exhaled gases or oxygen.

This application is a continuation in part of our application, Serial No. 227,588, filed August 30, 1938.

The organization of elements by which these objects, purposes and advantages are obtained, and the detailed parts ofthis organization which cooperate to produce the advantageous results of our invention, are hereinafter described in the specification, and the novel features are particularly pointed out in the claims. In the drawings illustrating application of our invention in one of its forms- Fig. 1 is a front elevation view of our mask in section through the'breathing chamber and the tubes as the same appears upon an average face of a wearer, all approximately life size.

Fig. 2 is a side elevation view on a reduced scale of the appliance held inposition upon a wearer.

Fig. 3 is a sectional view taken on the line 33 of Fig. 4.

Fig. 4 is a sectional elevation view of our entire inhalation apparatus taken through the center of the nasal chamber and of the supported tube and rebreathing bag.

Fig. 5 reproduces a part of what is shown in Fig, 4 as the same would appear on the face of a wearer.

Fig. 6 is a sectional view taken on lines G6 of Fig. 4.

Fig. 7 is a transverse sectional line of Fig. 9.

Fig. 8 is a plan view of the mask appliance looked at toward the open side of the nasal chamber.

Fig. 9 is a plan view of the entire inhalation apparatus viewed from the opposite side from view taken on Fig. 8.

Fig. 10 is a sectional view taken on line llil of Fig. 8.

Fig. 11 is a sectional view taken on line Hl l of Fig. 9.

Considering first the assemblage as shown in Figs. 2, 3 and 9, a somewhat bulbous rubber member l of the shape shown specifically in the above mentioned figures, forms a nose receiving chamber I6. The member I 5 is narrowed as indicated at l8 and i9, Figs. 8 and 9, to produce a shaped, yielding nose piece 20 which includes a narrowed extension 2| of the chamber IS. The nose piece 20 is of moulded rubber which normally has an elastic force tending to cause it to assume the position of Fig. 8, and which is additionally held in a position to'gently clasp the sides over the bony structure of the nose by means of spring fingers 22 extending outwardly frompreferably metallic members 23 and 23 secured by rivets or other suitable means to the side walls of the member l5. There are, of course, two of these metallic members, one on each side of the member 20, so that there is a finger 22 tending to urge the walls of the extended portion 20 against the soft parts and towards the bony structure of the nose beneath to effect sealing, as clearly shown in Fig. 1.

A nose-receiving extension 20 is provided with beveled faces 24 coming to a substantial lineal edge as indicated at 25, Figs. 4, 5 and 8, and these beveled faces extend into faces 21 and 28 best shown in Fig. 8, which flare outwardly and are adapted for sealing purposes to engage the soft parts above the bony structure of the front of the cheeks. From the faces 21, 28 extends a lip 29 curved as indicated at 30 of Fig. 10, which lip 29 has its curved surface 30 held upon the upper lip of the wearer, as indicated in Figs. 1 and 6, by means of a yieldable fastening strap shown in Fig. 2. This strap extends through and is secured by the metallic side members 23 and 23, with a shorter end 3| on one side extending from member 23 and a longer portion 32 extending from the other fastening member 23, as clearly shown in Fig. 3. The length of the end 32 may be adjusted as need arises by means of the adjustable clasp member 33 shown in Fig. 2. The short member 3| is provided with' a hook 34 which engages within a slot 35 in a metallic fastening member 36 on the long strap 32.

By means of the straps 3| and 32 the appliance will be held in position over the nose and upon the fronts of the cheeks of the wearer with very slight pressure from the elastic members 3! and 32 so as to seat the beveled faces 24, 21 and 28 and the face 25 over the top of the nose, and against the soft parts over the bony structureof the sides of the nose and over the bony structure of the fronts of the cheeks and so as to bring the lip or face 29 firmly but gently in contact with the upper lip of the wearer whereby the nasal breathing chamber I6 is sealed both from the reception of outside air on inhalations and from the outgoing of exhalation gases. The member 23 is additionally provided with a spring finger 31 to additionally urge the beveled faces 24 against the soft parts over the bony structure of the front of the cheek. It will be noted as to the spring fingers 22 that they have curved faces or ends 38, Fig. 3, and that these faces and the bodies ,of the spring members themselves are so adjustable that when the nose extension 20 is spread open by the placing of the same upon the nose of a wearer, the curved ends 38 will engage the sides of extension 20 with their full faces and with just pressure enough to effect sealing at that point.

Having reference particularly to Figs. 1 and 5, it will be noted that there is a substantial space 40 at the front of the nose 4| and substantial and expanding space 42 below the nostrils 43. And furthermore, there is substantial space 44 about the alae nasi indicated at 45 in Figs. 1 and 5. .All of these spaces are connected together and are connected through tubes 46 and 41 with passages 48, 49, extending from the lower corners of the chamber l5, as clearly shown in Figs. 1, 8 and 9, to come together in a transverse tubular member 52 from which a central outlet tube 53 extends.

The above indicated arrangement of connected spaces within the nasal chamber 2| as the mask is worn, in relation to the outlet passages 48, 49, is such as to enable the wearer to breathe without restriction, permitting the alae nasi to move in expansion and the nostrils to dilate in the same manner and with substantially the same case and comfort as when no mask is worn.

At the same time with a 'very' little pressure from the elastic bands 3!, 32, comfortably absorbed by the beveled faces 24, 21, 28 and 29 against the soft parts of the face and fitted to the bony structure underneath, there is very complete sealing action of the open face of the entire nasal chamber l6.

Inasmuch as the inhalation apparatus as a whole, for the uses for which it is intended, requires a reservoir through which oxygen for breathing is delivered, and which reservoir has also the functions of a rebreathing bag, we have found it to be of great advantage to support this combination reservoir and rebreathing bag, together with means for introducing oxygen thereinto and for regulating the percentages of mixture of oxygen and air, directly upon the outlet tube 53. In this connection, a problem was leave the mouth free and unobstructed and at the same time not have any tendency to twist or unseat the nasal mask proper thereby to break its seal. Both for this and for the reason that it is desirable to provide breathing passages for each nostril without in any way restricting or confining the nostril or the alae nasi, the union of the outlet tubes 46 and 41, to produce the outlet passages 48 and 49, to and with the nasal mask member [5 is of very high importance. It is not only necessary to avoid any kind of interference with the mouth but also highly important to have the passages 48 and 49 leave the nasal breathing chamber l6 and the various parts thereof in a manner to make most efficient the movement of air from and to the nostrils with substantially complete elimination of restriction or requirement of increased effort. After extensive experimentation, we discovered that by carrying the outlet tubes from the lower corners of the nasal breathing chamber natural breathing with practically no difference from breathing in the open air was made possible. Then by carrying the tubes from that position in a backward curve as indicated at 5| of Fig.4, while at the same time curving these tubes about an area to fully expose the mouth, and positioning the transverse connecting tube 52 so as to have a portion 55 thereof, Figs. 2 and 5, directly resting upon the chin we discovered there was no tendency for the reservoir-rebreathing bag and connected parts to disturb or put out of position or break the seal of the nasal mask itself.

To the tube 53 which extends centrally from the transverse tube and opens into passageway 52 is secured a connector part 54 which also includes regulating means, and which, as shown,

.comprises a metallic sleeve member 55. This member comprises a socket extension 56 over which the tube 53 can be slipped to hold the same upon the connector part 54 and a lower socket extension 51 to which the neck 58 of reservoirrebreathing bag 59 is secured. A boss 60 extends to one side and is internally threaded to hold a screw cap 6| within which is a compression spring 62, or other means to prevent the valve opening with less than one cm. water pressure, engageable with an outwardly movable check valve 63, there being escape ports 64 from the sides of the boss 60. above the valve 63.

The force of spring 62 is such that upon an exhalation it will retain valve 63 closed until the reseryoir-rebreathing bag 59 is distended by the simultaneous inflow of oxygen and the first part of the expired air. The distending of the rebreathing bag is'thus effected without any loss of infiowing oxygen which joins with the incoming expired air. However the reservoir-rebreathing bag has a maximum containing capacity which is less than the expiration volume of a normal individual, and for greater efficiency in use of oxygen should be of different sizes for men, women and children. It will, of course, be practicable to have a reservoir-rebreathing bag for any individual of a size such that its distended volume capacity will be less than the expiration volume of that individual, so that in passed to atmosphere, the carbon dioxide content of the rebreathed mixture will become too high. Further, as is well known, the last part of the exhalation gases are those most heavily charged with carbon dioxide, and this is the part which is expelled from the system, which has exactly the desired effect of constantly eliminating sufficient quantities of carbon dioxide to keep the mixture suitable for breathing.

A tube 65 is connected with a source of oxygen supply delivered at suitable pressures for breathing through pressure controlling means and flow-meter valve mechanism, (not shown), in a well known way, and at a controlled rate of flow per minute to maintain the desired concentration of oxygen in the inspired air. an extension 66 depending through the tubular member 55, and extension 66 has connected therewith a, rubber tubing 61 which opens at 68 near the bottom of the reservoir-rebreathing bag 59. In this manner oxygen may be kept flowing to 'the bottom of bag 59 at variable volumes determined by the flowmeter, which is adjustable through pressure reducing valves (not shown) in a well known way. In practice there will always be a stream of oxygen flowing into the space'near the bottom of the reservoirrebreathing bag and this oxygen is caused to be mixed with the exhaled gases which distend the rebreathing bag until the last of the exhalation gases exhaust through the valve structure above described. And since the volumetric capacity of the reservoir-rebreathing bag is less than the volume of a normal exhalation, it follows that it will be less than the volume of a normal inhalation, unless oxygen is delivered at such a rate of flow that the patients full inhalation capacity is supplied by incoming oxygen, which is the desired condition where an inhalation appliance is used for the breathing of substantially per cent oxygen. Under other conditions, such for example as occur when the inhalation appliance is used for breathing in rarified air, only an amount of oxygen suitable when mixed with a certain amount of atmospheric air and exhalation gases to maintain a desired oxygen supply to the user of the appliance will be required, and the users inhalation will draw in atmospheric air and exhalation will discharge to atmosphere the parts of the exhalation gases which come last and which contain the largest proportion of carbon dioxide.

The use of the reservoir-rebreathing bag not only aids in satisfactory delivery of added oxygen to the mixture being breathed, in such proportions, up to 100 per cent oxygen, as may be indicated, but it has an extremely important func..

tion in conserving the oxygen. Since oxygen must be added as it is breathed, for the layman and with an inexpensive apparatus there must be a constant flow both during inhalation and during the expiratory phase of respiration. If, through the use of the reservoir-rebreathing bag the oxygen flowing at this time were not thus conserved, two-thirds to three-fourths of the oxygen supply would be wasted. As an additional advantage, the first part of the expired air, which contain an excess of oxygen from the previous oxygen-enriched inspiration, will also be conserved and thus further decrease the amount of oxygen which must be supplied and thereby makes this new oxygen therapy more economical to the patient.

Such addition of atmospheric air in varying amounts as conditions may require, is made This tube 65 has possible by the valve structure in the connectingregulating device shown in Fig. 6 and also indicated in part in Fig. 4. As there shown, a multiplicity of ports or holes 69 is provided in the inner tubular member 55. A sleeve I held by a nut H is provided with a corresponding number of holes 12. By rotating this sleeve by means of finger piece 13 so as to bring one or more of the holes I2 in alinement with holes 69, a greater or less combined air inlet to within the tube may be obtained, from none at all, where all holes are closed, through one, two, three or-any number of holes which may be provided and which may be opened. It follows that with the very slight negative pressure established by inhalation, air will join the stream of gases coming from the reservoir-rebreathing bag in proportion to the extent of opening effected by the valve member 10. This will not, however, affect the emptying of the rebreathing has, since itselastic walls tending to collapse the bag will cause a certain amount of positive pressure tending to move its contents to the breathing passages, and being joined by the air coming in through whatever holes I2 are open. This, and the predetermined rate of flow at which the oxygen stream is being delivered to the reservoirrebreathing bag, will determine the proportions of oxygen in the mixture being breathed.

Other means may be employed for admitting the desired amount of atmospheric air when the admission of 100% oxygen is not required and at the same time excluding such air when 100% of oxygen is required, and We do not wish to limit ourselves to the particular means shown. One alternate arrangement for the above stated purpose is to substitute in place of the air portholes in the rotating sleeve an inspiratory valve similar to the expiratory valv provided with a light spring or other yielding means which will produce resistance to inspiration or negative pressure by said valve amounting approximately to one cm. water pressure. Such an inspiratory valve mechanism may be positioned on the connector regulating tube of the construction as shown, or it may be placed in a sleeve member in the reservoir rebreathing bag at or near its bottom.

Another modification which would simplify our construction and make it lighter would be of advantage for use in airplanes that do notascend to an' elevation above 25,000 feet. Under such conditions in aviation, where it is not necessary forthe aviator to inspire 100%; oxygen by excluding the inhalation of atmospheric air, the apparatus can be lightened and simplified by elimination of the rotating sleeve, thus leaving the three openings in the connector regulating device always open. With this arrangement the expiratory valve can likewise be eliminated, with the result that air ,will be introduced into the stream going to the lungs on inhalation, and

parts, principally the latter part of exhalations will go to atmosphere.

In general, the operation of our invention, con sidered as a mask, and also as an oxygen administering inhalation device, is as follows: By reason of the, fact that we have, by experiment, determined the conformation of the bony structure of the nose, the forward part of the cheeks and the outer front of the upper jaw, and have developed a nasal mask structure having margins which substantially conform to the outline of the aforesaid bony structure, we have produced a nasal mask arrangement such that with a single structure practically all mens faces will be fitted. With the same sortof experimental development, we have produced a nasal mask in which a single specimen will fit substantially all types of female faces.- This mask will be placed in position as shown in Figs. 2 and 6 and after the flexible strap 32 has been adjusted for length, it will be passed around the back of the head about at the nape of the neck and secured to the hook on the shorter strap member 3|. This will hold the mask in position, exercising a gentle and comfortable pressure upon it so as to cause the marginal beveled contours of the mask, developed as above indicated, to come over the corresponding bony structure of the, face above the soft parts which cover this bony structure, with the result that the contacting beveled faces of the mask will effect an efficient and substantially complete seal from outside air.

As worn in this position, the mask will be held upon the wearer with no discomfort and the mouth will be free for talking, drinking, eating or the like, in fact the mouth will be free at all times. The incurved portions of the tubes 46, 41 will lie against the front of the cheeks at eitherside of the mouth, running in towards the lower jaw where the transverse connecting tube 52 will have its inner transverse face resting upon the chin of the wearer with the attached par-ts including the reservoir-rebreathing bag depending downwardly. In this position the nasal chamber, as indicated in Figs. 1 and 5, gives a large amount of room around the end portion of the nose, the openings to the nostrils and the alae nasi. The tubes 46, 41 enter this chamber in such a way that the breathing of the wearer is effected in substantially the same manner, and with as little restriction, effort or discomfort, as would be the case when breathing in open air. Meanwhile, the rebreathing bag and other par-ts connected withthe central tube 53 will hang downwardly to be supported over the chest, and owing to the backward curvature of tubes 46 and 41, will haveno tendency to pull down on the nasal mask proper, but rather will tend to aid the'straps 3|, 32 to hold it firmly in sealing position. Upon inhalation, the reservoir-rebreathing bag 59 will first be emptied of its contents, including oxygen which has been introduced into the bottom of the rebreathing bag. Meanwhile air will enter through such of the openings 69 as are in alinement with openings M of rotary valve member III to provide ingress for such air, and will enter in increased volume after the reservoir-rebreathing bag is emptied. This air will mix with .the rich mixture of oxygen and respiration gases, or of pure oxygen as the reservoir-rebreathing bag is nearly emptied, and will provide, in conjunction with rebreathed exhaled gases, a mixture having a desired concentration of oxygen for the conditions to be met for the breather, such as in rarefied air at high elevations, or in oxygen-therapy for alleviation of pathological conditions of a patient. If those conditions, or any condition of an individual, call for the breathing of per cent oxygen over a considerable period of time, the openings 12 of rotary valve member I0 will all be closed, and the inflow of oxygen be considerably increased, so that the breather will get. no admixture of atmospheric air, and will relieve of excess carbon dioxide by expelling the last part of each exhalation, containing the least oxygen and the most carbon dioxide, to atmosphere. As it is drawnin or inspired the stream of oxygenated gas mixture will divide so that part of it goes through tube 49 and will enter the portions 42 and 45 of the nasal chamber H in a manner to be easily and naturally drawn in through the breathers nostrils, the space. above the wearers nose permitting such expansion as will prevent any cramping or restriction of these air currents.

At the termination of a full inspiration, the

. reservoir-rebreathing bag 59 willbe entirely emptied except for such amounts of oxygen as may be running into it at the termination of inspiration, and all of this continued flow of oxygen will be conserved and none of it lost. For immediately after termination of inspiration expiration will take place, whereupon the reservoirrebreathing bag will become fully distended with the inflowing oxygen and the first portion of said expiration, following which the built-up pressure will push valve member 63 outwardly to open outlet port 64 and the later part of the for the first time in the history of oxygen therapy it permits administration of 100 per cent oxygen in the inspired air with comfort to the patient and in an economical and practical manner, such that the layman may employ it without requiring the services of a skilled anaesthetist or other attendant. As a result this invention opens up expiration will waste to atmosphere, carryingwith it the gases most highly charged with carbon dioxide. This-feature of conserving oxygen and wasting part of the exhaled gases to atmosphere is essential, as otherwise the rebreathed gases would become too highly charged with carbon dioxide,and would affect the breather unfavorably, even if, at unreasonable cost, oxygen were added in sufficient quantitiesto prevent any tendency toward asphixiation.

Since this feature of our invention, wherein the capacity of the reservoir-rebreathing bag must be substantially less than the volume of gas expelled in a full expiration, is both advantageous and important, to insure that the capacity of the reservoir-rebreathing bag will be substantially less than the volume of an expiration multiple sizes of rebreathing bags may be employed, so that a suitable size may be available for any prospective wearer. We also have found it practical and effective to use the means indicated in Fig. '7 for varying the volumetric capacity of the rebreathing bag.

As shown in 7} the side walls 15 and 16 in collapsed form will come parallel with portions of the rebreathing bag 11 and I8 folded within. By putting one or more snap fastenings 19 upon the adjacent portions of the folds l1 and [8 it is practical to change or adjust the volumetric capacity of the rebreathing bag 59 through several different sizes, and this form of adjustment may take the place of the employment of different sizes of bags. l I v The advantages .of our invention have been quite fully covered heretofore in connection with the detailed description thereof. One important advantage, is of course, that an economical and highly efficient means of adding oxygen (or other gas which may be indicated) to the mixture of gases being breathed is provided, such that very little inconvenience or discomfort is experienced bythe patient and the mouth is left entirely free for its normal uses. This desirable advantage accrues to persons in normal health, who for any 'reason, require added oxygen (or other gas) because, for example, of being in an attenuated atmosphere deficient in the normal content of oxygen, as at high elevations in aviation. The advantage of easy and comfortable breathing is also, of course, of great importance in the use of oxygen therapy for patients in ill health or weakened by the inroads of disease.

An advantage of the use of this apparatus which may be the most important of all, is that an entire new field of oxygen therapy, and patients suffering from conditions hitherto not considered as benefited by oxygen therapy, or for whom the cost of oxygen therapy has been too great to permit its use, now can be relieved and often cured of their difficulties.

Our inhalation apparatus also for the first time puts efficient and economical oxygen therapy, with comfort to the patient, in the hands of the small town and country doctor, at a cost to his patients which they can afford to meet, and is therefore, a means of oxygen therapy which will prove more effective and obtain better results than the employment of the costly oxygen tents or inefficient nasal catheters, neither of which can be used for the administration of 100 per cent oxygen in the inspired air, and both of which may require attention of trained experts.

We claim:

1. A nasal mask comprising a semi-rigid casing wherein is an open-sided chamber for receiving the nose of the wearer, said chamber being extended downwardly and spread laterally and bulged outwardlyso that when worn there will be a substantial free space between the inner walls of the chamber and the ends of the nostrils and about the alae nasi, the marginal and contacting parts of said chamber formed to comfortably fit the face and seal the chamber when the mask is worn, and tubes extending downwardly and divergingly from the lower corners of said free space to form passages which are substantially in direct communication with and an extension of the nostril passages, said tubes being curved rearwardly and then forwardly with respect to the frontal plane of the face when worn, so as to engage the face of the wearer at the sides of the mouth to aid in holding the mask comfortably in position.

2 A nasal mask comprising a semi-rigid casing wherein is an open-sided chamber for receiving the nose of the wearer, said chamber being extended downwardly and spread laterally and bulged outwardly so that when worn there will be a substantial free space between the inner walls of the chamber and the ends of the nos.- trils and about the alae nasi, the marginal and contacting parts of said chamber formed to comfortably lit the face and seal the chamber when the mask is worn, and tubes extending downwardly and divergingly from the lower corners of said free space to form passages which are substantially in direct communication with and an extension of the, nostril passages, said tubes being curved rearwardly and then forwardly with bulged outwardly so that when worn there will be a substantial free space between the inner walls of the chamber and the ends of the nostrils and about the alae nasi, the marginal and contacting parts of said chamber being formed to comfortably fit the face and seal the chamber when the mask is worn, side tubes extending from the lower corners of the chamber and united in a single inlet-outlet tube, a rebreathing bag connected therewith and held thereby close to the mask, and means including a tube supported by the rebreathing bag for delivering oxygen directly to the rebreathing bag, the side tubes diverging and extending downwardly and rearwardly and then forwardly with respect to the frontal plane of the face when worn, so as to .engage the face of the wear at the sides of the mouth and across the sublabial part of the chin to aid in holding the mask and the rebreathing bag and oxygen supported by the mask comfortably in position.

WALTER'M. BooTHBY. ARTHUR BULBULIAN. WILLIAM R. LOVELACE.

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