US3100485A - Respiratory apparatus - Google Patents

Description

Aug. 13, 1963 R. G. BARTLETT, JR

RESPIRATORY APPARATUS Filed March 7, 1961 3 Sheets-Sheet l FJQJ.

FRDH OXYGEN SUPPLY JNVENTOR. F0 5:05 G. BMWZETT JR.

BY E

ATTORNE 7 1963 R. G. BARTLETT, JR 3,100,485

RESPIRATORY APPARATUS Filed March 7, 1861 3 Sheets-Sheet 2 a: 52 53 a 6 MW 644- 46 42' y j k WATV/JV/AW/TV/FV/A/TF/TVW/ INVENTOR.

ATTORNEY I 36 Roscoe G. BARTLETT J Aug 13, 1963 R. s. BARTLETT, JR 3,190,485

RESPIRATORY APPARATUS Filed March 7, 1961 3 Sheets-Sheet 3 3 9 INVENTOR Roscoe G. BARTLETTJR.

.2; a BY ATTORNEY United States Patent 3,190,485 RESPIRATORY APPARATUS Roscoe G. Bartlett, .lr., Liliian, Ala. Filed Mar. 7, 1961, Ser. No. 94,691 5 Claims. (Cl. 128-142) (Granted under Title 35, US. @0113 (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates generally to respiratory apparatus and particularly to an improved respiratory apparatus providing adequate moisture transfer, self-regulating breathing stimulus, and economical use of supplied pressurized oxygen.

To prevent the freezing of valves, gauges, and other gear associated with the storage of oxygen, both the liquid and compressed forms of this gas are supplied to theuser in as dry a form as possible, i.e., all water or water vapor has been extracted. Although breathing of dry oxygen for a short time is without serious effects, prolonged breathing results in drying of the mucous membranes of the respiratory tract with accompanying discomfort, sore throat, and head colds. Where, at high altitudes or other perhaps clinical reasons, pure oxygen without air dilution must be supplied to a user, some means of humidifying the oxygen breathed by the user must be supplied. Such humidification could be accomplished by bubbling the oxygen through water, passing it through a water spray, or passing it through or over water containing material. Such means have the principal disadvantage that the moisture must be supplied from an external source which, with the necessary apparatus, increases the weight of the device and limits the duration of its use.

Another approach to the problem concerns the recycling of water from the moist expired breath to the dry incoming oxygen. This method has several merits. First, the device would be self-perpetuating in operation and obviously would be much lighter than if water were continuously supplied from an outside source. Second, in a small confined space, such as a cockpit or space capsule, this method of recycling would be advantageous in maintaining low humidity of the atmosphere therein, thus preventing many of the problems associated with thecondensation of water on the instruments or viewing ports.

The undesirable effects of hyperventilation leading to an abnormal loss of carbon dioxide from the blood are well known. On an average, the human body maintains a constant volume of carbon dioxide in the lungs, approximately 5.6%. This CO is necessary for the health and well being of the body. A rise in the percentage of CO increases the rate of breathing; an increase of 0.2% generally doubles the rate of breathing. A fall in the per centage decreases the rate of breathing with danger of cessation and dangerously upsets the acid-alkaline balance of the human physiological system leading to alkalosis.

Hyperventilation may be caused by various physiological, psychological and physical factors. One of these fac tors is that the respiratory passages ofler little resistance to the movement of the rarefied atmosphere at high altitudes. This condition leads to the users sensation of an inade quate alveolar ventilation. The use of the mask, itself, pro- 3,10%,435 Patented Aug. 13, 1963 duces a sensation of suffocation that induces a tendency toward induced rapid and deep breathing. The use of respiratory apparatus presents diflerent pressures to the respiratory tracts and lungs which, again, leads to hyperventilation, even in the experienced.

In using oxygen from a compressed source in a respiratory apparatus, it is obvious that some oxygen will be lost to the surrounding atmosphere. As the supply of oxygen is naturally and necessarily limited, due to weight and space limitations, every effort must be made to conserve this fluid and prevent its loss.

The principal object of my invention, therefore, is to provide a respiratory apparatus, particularly for aviators flying at high altitudes, including space flight, which will eiilciently incorporate the foregoing features of moisture transfer from expired to inspired breath; the alleviation and prevention of hyperventilation; and planned economy in the use of-the limited supply of additive respirant fluid.

Another object of myinvention is to provide a respiratory apparatus wherein the mask used to couple the apparatus to the respiratory tracts may be extremely simple, valveless, light of weight and offer no obstructions to voice communications when a proper microphone is borne thereby.

A further object of my invention, contrary to the standard practice heretofore employed, is to provide an added anatomical dead space to and in the respiratory apparatus for promoting better and more effective breathing by the user.

A still further object of my invention is to provide respiratory apparatus wherein the functions of moisture transfer and increased, improved ventilation are selfpriming and self-perpetuating in that no external sources of moisture or other external arrangements for promoting breathing are necessary.

Other objects and advantages of my invention will appear in connection with the following detailed description and the accompanying drawings wherein:

FIGURE 1 is a partly sectioned perspective view of my improved respiratory apparatus;

FIG. 2 is a partly sectioned plan view of the principal respiratory member;

FIG. 3 is a sectional side elevation of the respiratory member taken on the line 3-3 of FIG. 2;

FIG. 4 is a partly sectioned end elevation of the respiratory member taken on the line 4-4 of FIG. 3;

FIG. 5 is a partly sectioned end elevation of the respiratory member taken on the line 5-5 of FIG. 3; and

FIGS. 6-11, inclusive, are diagrammatic views illustrating the principles of operation of my improved respiratory apparatus.

With reference to FIG. 1, my improved respiratory apparatus comprises a valveless mask 20, a flexible tube 21, a

respirant supply flexible tube 22, and the principal respirar 3 presence of valves in the mask near the microphone not only present a noise problem due to the operation of the valves but the latter also serve to distort the sound waves between the larynx and the microphone.

The tube 21 between the mask and the respiratory memher 31 is provided for the important function of designedly increasing the anatomical dead space between the lungs and the necessary expiratory and inspiratory valves.

Heretofore, it has been considered mandatory to keep the connections between the mask and the source of added respiratory fluid as short as possible. Such limitation has been imposed apparently because of the fancied overstressed difficulties in breathing at high altitudes and also possibly because the designers envisaged the use of open cockpits subject to the extreme low temperatures there encountered. In the latter prior art, showing the addition of a rebreather bag between the valved mask and the oxygen source, it is universally asserted that the volume of the rebreather bag must always be less than the normal volume of air contained in the expanded lungs of the average user. This requirement was based on the assumption that some provision had to be made to expel as much of the expired CO as possible. Actually, it has been found that, at high altitudes and under conditions requiring the breathing of practically 100% oxygen for prolong-ed periods, such arrangements eliminated too much from the respiratory system and resulted in the physiological effects previously mentioned with reference to the lowering of the CO content of the lungs. Consequently, tube 21, having a volume of approximately 250 cc. in the prototype has been added to correct this deficiency. The actual use of this added anatomical dead space and its important functions will be more fully described later.

Tube 22 is supplied to furnish the necessary connection between the respiratory member and the source of pressurized respirant (not shown).

Respiratory member 30, as shown in FIGS. 2-5, inclusive, consists of a hollow box-like structure 32 having a top lid portion 34; a bottom portion 40; end pieces 50, 51; an expiratory valve 60; an inspiratory valve 70; a flexible bellows or diaphragm S0; and a wicking or moisture transfer membrane 85.

Top lid portion 34 may be hollowed out or may be constructed, as shown, from five rectangular pieces of material, i.e., top plate 35, side pieces 36 and end pieces 37. T hese' pieces may be rabbeted, as shown, and are hermetically-sealed to each other by adhesive or cement reinfo rced by the screws 38. An aperture 61 is provided in top plate for communication with the expiratory valve 60. Upper ports 39 are provided in the end pieces 37 for the passage of breathing fluids as will be more fully explained later.

The bottom portion 40 is constructed to match the lid portion 34 and may consist of sides 41, end pieces 42, 43, and a perforated bottom'plate 44. As in the lid portion,

the side and end pieces may be rabbete-d and adhesively secured together, further reinforced by the screws 45. Lower ports 46 may be formed in the left hand end piece '42 for purposes to be hereinafter described. Bottom plate 44 is provided with a plurality of apertures 47 for leading atmospheric air into the bottom portion.

The flexible impervious diaphragm or bellows 80 is enclosed in the bottom portion 40 and is secured hermetically between the sides 41, end pieces 42, 43, and the lower bottom plate 44. This bellows is of a size suflicient to substantially fill the entire bottom portion 4t) when distended.

The wicking or moisture transfer membrane 85 is stretched and hermetically sealed between the upper and bottom portions of the respiratory member 30. This wicking may be of any suitable material with the important limitation, however, that its structure must produce transverse channels for the capillary action required in transferring moisture from the lower portion to the upper portion of the respiratory member. 0f the many materials 4. tested, a commercial'disposable hand towel, made of rag and wood fibers laid down by a felting process, was found to give the best performance. Other materials could, of course, be specially designed and constructed for this purpose.

Top plate 35 supports the vertically extending expiratory valve 6i). As shown in 'FIG. 3, this valve may be of more or less standard construction and consists principally of a spring loaded valve plate 62 pressed against its seat 63. By varying the loading of the spring 64, this valve may be set to allow discharge of the expired breath at a desired pressure relationship. Aperture 61, of course, provides the egress from the chambers in the respiratory member 30 to and through the valve 60.

. The inspiratory valve 7%, as shown in-FIGS. 2 and 3, which is supported by end piece 51, may also be of standard construction. Itconsists principally of a supporting case 71 which may be screwed into a threaded hole in the end piece. This casing bears the tube 22 connector 72 with its usual sealing rings 73. A thin perforated diaphragm 77 is supported in the other end of the casing. A flexible rubber diaphragm 74 is supported inwardly of the other diaphragm by the spider 75 and the spindle 76. When inspiring, the partial vacuum created in the respiratory member 30 with the pressure of the incoming respirant forces the rubber diaphragm to open to the left or inwardly, as indicated in phantom in FIG. 2.

The end piece 50, FIGS. 2 and 3, is formed with an integral connector 52 for connection to the tube 21. This end piece 50 is provided with an internal, rectangular cavity 5 3 which connects the bore of connector 52 with the four ports adjacent thereto.

As previously noted, end piece 42 of the bottom portion 40 is formed with two oblong ports 46 which are the same size as ports 39 formed in the top portion end piece 37. Thus, at the mask end of the respiratory member 30' there are four ports, two above the wicking and two below. At the pressurized gas end, there are only two ports and these are situated above the wicking. With this porting arrangement expiratory fluid can pass both below and above the wicking while the inspired supplied respirant must pass above the wicking.

The principles of the operation of my invention will now be described in connection with FIGS. 6-11, inclusive.

FIGS. 6 and 7 illustrate diagrammatically the recycling of the moisture from the expired to the inspired breath.

During the first part of the expiration, FIG. 6, the lower chamber of the respiratory member is filled with moist warm air; the bellows or diaphragm .80 collapses on the perforated bottom plate 44. As this air cools, the moisture condenses out on the walls of the chamber and the upper surface of the bellows. As the expiration continues, the expired air passes into and through the upper chamber over the wicking and then the remainder passes outwardly through the expiratory valve 60. During this latter period, as the velocity of the expired air is diminished, condensation of moisture is occurring also throughout the length of the added anatomical dead space represented by the tube 21.

During the first part of the inspiration, as shown in FIG. 7, the negative pressure or suction produced empties the lower chamber of the respiratory member 30 before the inspiratory valve opens to admit the oxygen or other respirant from either a liquid or compressed fluid source. The air or fluid trapped in this lower chamber is, of course, humidified. When the bellows or diaphragm is forced against the wicking material, all of the condensed moisture is transferred to and through the wicking or moisture transfer membrane. The first part of the inspired breath, then, should be 100% moisture saturated. The second part of the inspiration is respirant which has been drawn over the upper surface of the wicking where it is partly humidified. As the partially humidified respirant is drawn along the added dead space tubing, it picks upfurther moisture from that condensed on these surfaces until, as the respirant reaches the mucous membranes and lungs of the user, it has been substantially humidified. Because of the temperature difference between the ambient atmosphere and thebody of the user, it should be stressed that only 50% of themoisture from the expired breath need be trapped to saturate completely the inspired breath. It should also be noted here that excess moisture is eliminated during expiration through the expiratory valve and as the remaining moisture trapped in the added dead space and the respiratory member and on the wicking is utilized completely in humidifying the inspired breath, including the 100% dry respirant, no moisture can collect as an unused liquid. This collection of unused moisture, which gradually filled the receptacles provided, was the fatal defect in all the rebreather types of apparatus found in the prior art.

FIGS. 8 to 11, inclusive, illustrate the functions and provisions of my invention in preventing hyperventilation, promoting better breathing, and saving respirant. These provisions consist of the added anatomical dead space provided by the tubing 21 and the respiratory member 30 which are used in the prevention of hyperventilation and the lower collapsible chamber of the respiratory member which traps the unused oxygen or respirant and makes it available as the first portion of the inspired breath.

FIG. 8 shows the beginning of expiration. The air in the upper portion of the lungs 86, the anatomical dead space 87, and the added anatomical dead space 21 is rich in unused oxygen or other provided respirant. This is first expelled and is collected and trapped in the lower chamber of the respiratory member 30 by collapsing the bellows or diaphragm 85 against the perforated lower or bottom plate 44. As the expiration continues, FIG. 9, and the lower chamber is completely filled, the latter portion of this air passes across the top of the wicking 85 and out through the expiratory valve 60. This latter portion is, of course, less rich in' oxygen. During the last stage of expiration, the alveolar air 88, which is rich in CO is expelled from the lungs into the anatomical and added anatomical dead spaces. The shaded portion 89, FIG. 9, indicates that portion of the air remaining in the anatomical dead space which is richest in CO As inspiration commences, FIG. 10, the expiratory valve 60 closes and the first part of the breath drawn into the lungs is the CO rich portion 89 which was present in the anatomical dead space and part of the added anatomical dead space tube 21. This CO rich mixture increases somewhat the rate and depth of respiration, as designed, and effectively prevents hyperventilation and its accompanying symptons of light-headedness, dizziness and disorientation. This portion is then followed by the O rich portion which was trapped in the lower chamber of the respiratory member due to the ambient pressures forcing the bellows 8t) upwardly against the wicking 85. Upon the exhaustion of the O rich gas from the lower chamber, FIG. 11, the inspiratory valve 70 opens and fresh oxygen or other respirant 91 enters the upper chamber over the wicking 85 and on into the succeeding passages and the upper part of the lungs.

As has thus been explained, the purpose of the added anatomical dead space is two-fold: (1) to provide a selfregulating stimulus for increasing the rate and depth of breathing; and (2) to provide a self-limiting reservoir of CO .for the prevention or reduction of hyperventilation. Although breathing tubing 21 has been used to produce these eifects, the added dead space could also be provided by a box or channel or space within an airtight helmet. The use of a breathing tube, however, permits the placing of the other components of the device at some convenient distance from the users mask.

While dimensions and materials are of no critical importance in the construction and operation of my invention, tubing 21 could contain approximately 250 cc. of fluid while the respiratory member 30 may occupy approximately 45 cu. in. of space. The tubing 21 may be of standard materials, textile or rubber. The respiratory .member 30 may be constructed of plastic or thin light metals. While the latter might be more advantageous insofar as maximum condensation is concerned, provision must be made for the hermetic sealing required. The materials of the bellows and wicking have been mentioned previously.

Having thus described a preferred embodiment of my invention,I do not intend, however, to be limited thereby. Such modifications as may suggest themselves to those skilled in the art will undoubtedly fall within the spirit of the invention and the scope of the appended claims wherein I claim:

l. A respiratory apparatus for users of pressurized respirant comprising:

a valveless mask adapted to hermetically cover the mouth and nose of a user;

a first flexible tubular connection leading outwardly from said mask, said first connection constituting an added anatomical dead space and a moisture collector from the expired breath of said user;

a source of dry pressurized respirant;

a second flexible tubular connection leading from said source of dry pressurized respirant;

a respiratory member interposed between said first and second connections and connected thereto, said res-' moisture therefrom, and a second chamber open to both first and second connections, said second chamber having an expiratory check valve leading to ambient atmosphere and an inspiratory check valve between said second chamber and said second connection to said source of respirant, said second chamber constituting a channel for conducting a portion of said expired breath to atmosphere and for conducting said dry pressurized respirant to said first connection incident to the controlled opening of said valves, and said respiratory member having a moistune transfer membrane separating said first and second chambers whereby the miosture collected in said first chamber is transferred to the dry respirant passing through said second chamber. 2. A respiratory apparatus as defined in claim 1 wherein said first chamber of said respiratory member has a main inner horizontal wallconsisting of said moisture transfer membrane and a main outer horizontal wall consisting of a flexible diaphragm, said flexible diaphragm being capable of closely lining the other walls of said first chamber, including contacting the entire undersurface of said membrane.

3. A respiratory apparatus as claimed in claim 1 wherein said respiratory member is a box-like structure comprising:

a shallow lid portion having side and end walls depending from a horizontal top plate;

an opening through said top plate;

said expiratory check valve mounted 'on the outer surface of said top plate over said opening;

a plurality of ports in each end wall, said ports leading to said first and second connections;

a bottom portion having side and end walls extending upwardly to meet the walls of said lid portion;

a perforated bottom plate in said bottom portion secured to said end and side walls;

a flexible diaphragm hermetically secured between said bottom portion end and side walls and said perforated bottom plate;

a plurality of ports in one end wall of said bottom portion, said ports leading to said first connection;

a moisture transfer membrane hermetically secured between the respective end and side walls of said lip and bottom portions; and

said inspiratory check valve interposed between the I? Y r plurality of ports in one of the end walls of said her, including the inner surface of the diaphragm, to the lid portion and said second connection. underside of said moisture transfer membrane;

4. A respiratory apparatus as claimed in claim 2 Wherein said first chamber of said respiratory apparatus has an additional perforated rigid outer yvall disposed in juXta- References Cited m the file of thls Patent position to said flexible diaphragm whereby the interior V UNITED STATES PATENTS surface of said diaphragm is subject to the pressures of 2,387,123 Deming Oct 16 1945 the expired breath trapped therein and its exterior sur- 2,610,038 Phillips Sept 9 1952 face is subject to ambient atmosphere pressures. 3,005,453 wenenstein et a1 Oct 24, 1961 -5. A respiratory apparatus as claimed in claim 2 where- 10 in said flexible diaphragm constitutes the means to trans- FOREIGN PATENTS fer the moisture collected on the walls ofssaid first cham- 1,121,482 France Apr. 30 1956

Claims (1)

1. A RESPIRATORY APPARATUS FOR USERS OF PRESURIZED RESPIRANT COMPRISING: A VALVELESS MASK ADAPTED TO HERMETICALLY COVER THE MOUTH AND NOSE OF A USER; A FIRST FLEXIBLE TUBULAR CONNECTION LEADING OUTWARDLY FROM SAID MASK, SAID FIRST CONNECTION CONSTITUTING AN ADDED ANATOMICAL DEAD SPACE AND A MOISTURE COLLECTOR FROM THE EXPIRED BREATH OF SAID USER; A SOURCE OF DRY PRESSURIZED RESPIRANT; A SECOND FLEXIBLE TUBULAR CONNECTION LEADING FROM SAID SOURCE OF DRY PRESSURIZED RESPIRANT; A RESPIRATORY MEMBER INTERPOSED BETWEEN SAID FIRST AND SECOND CONNECTIONS AND CONNECTED THERETO, SAID RESPIRATORY MEMBER DEFINING A FIRST CHAMBER OPEN ONLY TO SAID FIRST CONNECTION FOR THE TRAPPING OF THE FIRST PORTION OF THE EXPIRED BREATH AND THE COLLECTION OF

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