Disposable Carbon Dioxide Absorber

Abstract

A disposable carbon dioxide absorber having self-contained valves and being designed to be used once and then disposed of in order to eliminate certain hazards of reinfection and cross-infection.

Description

BACKGROUND OF THE INVENTION

This invention pertains generally to respiratory apparatus for use in administering anesthetic or therapeutic gases and more particularly to a disposable carbon dioxide absorber for use in absorbing gaseous carbon dioxide from a circulating mixture of gases in such respiratory apparatus.

Conventionally, in the operation of respiratory apparatus for use in administering anesthetic or therapeutic gases, a flow circuit is established, by means of suitable conduits, between a carbon dioxide absorber and a face mask, mouthpiece, trachial insert, or similar breathing appliance. In the carbon dioxide absorber, the products of exhalation pass from the breathing appliance through an inlet check valve into a canister, which contains granular barium hydroxide lime, soda lime, or other suitable material capable of absorbing gaseous carbon dioxide, and return to the breathing appliance from the canister through an outlet check valve. Accordingly, gaseous carbon dioxide is absorbed from the circulating mixture of gases, and the unused anesthetic or therapeutic gases and the unused oxygen are conserved for return to the patient. Normally, supplementary anesthetic or therapeutic gases and form oxygen are introduced into the circulating mixture of gases at the returning portion of the flow circuit according to the anesthesiologist's determination of the needs of the patient.

Carbon dioxide absorbers with disposable canisters are not new. However, heretobefore, the inlet and outlet check valves and the various necessary fittings to hold the canister, seal it from atmosphere, and the like have been designed for repeated use. It is believed that the repeated use of carbon dioxide absorber apparatus or parts thereof, from treatment to treatment is a possible cause of reinfection and that the repeated use of such carbon dioxide absorber apparatus, or parts thereof, from patient to patient is a possible cause of cross-infection. The hazards of reinfection and cross-infection attending the repeated use of carbon dioxide absorber apparatus, or parts thereof, may not be wholly eliminated by cold-gas sterilization or by sterilization with other commonly used techniques.

SUMMARY OF THE INVENTION

It is an important object of this invention to provide a completely disposable carbon dioxide absorber apparatus and material for use in respiratory apparatus.

It is another object of this invention to provide a carbon dioxide inner walls designed to be used once and then disposed of in order to eliminate the hazards of reinfection and cross-infection inner walls attending the repeated use of carbon dioxide absorbers, or parts thereof, in respiratory apparatus.

It is a related object of this invention to provide a disposable carbon dioxide absorber that is lightweight, compact and inexpensive.

It is a particular object of this invention to provide a disposable carbon dioxide absorber apparatus having self-contained inlet and outlet check valves and suitable absorption material.

The preceding objects may be attained in a disposable carbon dioxide absorber apparatus comprising a canister adapted to contain a gas permeable mass of carbon dioxide absorbent material, an inlet fitting cemented or otherwise integrally attached to the inlet end wall of the canister to communicate with the interior of the canister through an inlet opening in the inlet end wall, inlet check valve means permitting inflow of gases to the inlet fitting and checking reverse gaseous outflow from the inlet fitting, an outlet fitting cemented or otherwise integrally attached to the outlet end wall of the canister to communicate with the interior of the canister through an outlet opening in the outlet end wall, and outlet check valve means permitting outflow of gases from the outlet fitting and checking reverse gaseous inflow to the outlet fitting.

The disposable carbon dioxide absorber apparatus further may comprise retaining means in the form of retaining walls mounted within the integral canister adjacent but spaced from the respective end walls for retaining the permeable mass of absorbent material in spaced relation to the respective end walls while permitting gaseous flow from the inlet opening through the absorbent material to the outlet opening. Preferably, each retaining wall has a perforated portion and an inperforate margin, and the retaining wall adjacent the inlet end wall has an inperforate portion aligned with the inlet opening and adapted to deflect gaseous flow from the inlet opening toward the perforated portion. Additionally, an infeed stem may be integrally attached to a lateral wall portion of the outlet fitting.

So constructed, the entire carbon dioxide absorber is designed to be used once and then disposed of in order to eliminate the aforementioned hazards of reinfection and cross-infection.

These and other objects, features, and advantages of this invention will be evident from the following description, with the aid of the attached drawings, of a preferred embodiment of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective view, partly broken away, showing disposable carbon dioxide absorber apparatus embodying the principles of this invention;

FIG. 2 is a sectional view taken substantially along line 2--2 of FIG. 1 in the direction of the arrows;

FIG. 3 is a sectional view taken substantially along line 3--3 of FIG. 2 in the direction of the arrows;

FIG. 4 is a sectional view taken substantially along line 4--4 of FIG. 2 in the direction of the arrows;

FIG. 5 is a sectional view, analogous to FIG. 2, showing a modified form of carbon dioxide absorber apparatus embodying the principles of this invention; and

FIG. 6 is a sectional view taken substantially along line 6--6 of FIG. 5 in the direction of the arrows.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIGS. 1 through 4, there is shown disposable carbon dioxide absorber apparatus, indicated generally at 10, embodying the principles of this invention in a preferred form. The disposable absorber 10, which is designed to have particular utility in respiratory apparatus for use in administering anesthetic or therapeutic gases, generally comprises a canister portion 12, which has spaced end walls designated respectively as the inlet end wall 14 and the outlet end wall 16, an inlet fitting 18, preferably tubular, which is cemented or otherwise integrally attached to the inlet end wall 14 to communicate with the interior of the canister 12 through an inlet opening 20 in the inlet end wall 14, inlet check valve means 22 permitting gaseous inflow to the inlet fitting 18 and checking reverse gaseous outflow from the inlet fitting 18, an outlet fitting 24, preferably tubular, which is cemented or otherwise integrally attached to the outlet end wall 16 to communicate with the interior of the canister 12 through an outlet opening 26 in the outlet end wall 16, and outlet check valve means 28 permitting gaseous outflow form the fitting 24 and checking reverse gaseous inflow to the outlet fitting 24. Preferably, all of the parts of the carbon dioxide absorber 10 (other than the hereinafter described valve members of the check valve means 22 and 28) are made of a lightweight, inexpensive plastic material which is chemically inert relative to the carbon dioxide absorbent material to be used and with which the canister is filled and relative to the various gases to be used. The entire absorber 10 and absorbent therein is designed to be used once and then disposed of in order to eliminate the possibility of reinfection and cross-infection attending the repeated use of carbon dioxide absorbers or parts thereof in respiratory apparatus.

As illustrated, the canister 12 has a lateral wall 32. At least a substantial portion 34 of the lateral wall 32, adjacent the outlet end wall 16, is generally conically shaped and narrows toward the outlet end wall 16. The canister 12 is adapted to contain gas permeable mass 36 of carbon dioxide absorbent material (FIG. 2) such as granular barium hydroxide lime. Preferably, the carbon dioxide absorbent material contains a conventional color-changing indicator adapted to exhibit gradual change of color-indicating exhaustion of the capacity of the carbon dioxide absorbent material to absorb gaseous carbon dioxide. If such a color-changing indicator is used, at least the lateral wall 32 of the canister 12 is made of a transparent or translucent material permitting visual access to the absorbent 36. The use of such indicators is well known. Suitable transparent or translucent materials also are known to the art.

Retaining means 40 are provided, in the form of retaining walls 42 and 44 mounted within the canister 12 adjacent but spaced from the respective end walls 14 and 16, for retaining the absorbent 36 in spaced relation to the respective end walls 14 and 16 while permitting gaseous flow from the inlet opening 20 to the permeable mass 36 and from the permeable mass 36 to the outlet opening 26. Preferably, the absorbent 36 is densely packed and substantially fills the space between the retaining walls 42 and 44. Packing of the absorbent 36 is facilitated by the generally conical shape of the aforementioned portion 34 of the lateral wall 32 of the canister 12.

The retaining wall 42 has a generally annular perforated portion 46, which is adapted to permit gaseous flow from the inlet opening 20 to the absorbent material 36, and an imperforate portion 48, which is aligned with the inlet opening 20 and adapted to deflect gaseous flow from the inlet opening toward the perforated portion 46. The retaining wall 42 further has an imperforate margin 50. The inlet end wall 14 and the retaining wall 42 together define a chamber 52 within which gases flowing from the inlet opening 20 are dispersed over the entire portion of the absorbent 36 covered by the perforated portion 46 of the retaining wall 42. The imperforate portion 48 of the retaining wall 42 serves to reduce channeling of the mixture of gases through the central portion of the absorbent mass 36 by diverting gaseous flow from the inlet opening 20 toward the perforated portion 46 of the retaining wall 42. The imperforate margin 50 of the retaining wall 42 serves to reduce channeling of the mixture of gases between the porous mass 36 and the lateral wall 32 of the canister 12. Channeling of the mixture of gases is undesirable because it produces localized exhaustion of the capacity of the carbon dioxide absorbent material to absorb gaseous carbon dioxide and because it produces irregular color changes in such color indicator as may be used.

As shown, the inlet end wall 14 and the retaining wall 42 together form part of a detachable cover 54 for the canister 12. The cover 54 has a depending marginal flange 56. An upper portion 58 of the lateral wall 32 of the canister 12 is generally cylindrical, rather than generally conically shaped as the aforementioned portion 34, and has a bead 58a adapted to be snap-fitted into a suitably formed groove 56a in the marginal flange 56 of the cover 54. The cover 54 may be detached in order to permit the canister 12 to be filled with the carbon dioxide absorbent material. As shown, the marginal flange 56 of the cover 54 may be bevelled adjacent the groove 56a to facilitate replacement of the cover 54. After the canister 12 has been filled, the cover 54 may be replaced and then cemented or otherwise permanently secured in place.

The retaining wall 44 has a generally annular perforated portion 62, which is adapted to permit gaseous flow from the absorbent mass 36 to the outlet opening 26, and an imperforate portion 64, which is aligned with the outlet opening 26 and adapted to deflect gaseous flow from an adjacent portion of the absorbent 36 toward the perforated portion 62. The retaining wall 44 further has an imperforate margin 66. The outlet end wall 16 and the retaining wall 44 together define a chamber 68 within which gases passing from the absorbent 36 are directed to the outlet opening 26. The imperforate portion 64 of the retaining wall 44 also serves to reduce channeling of the mixture of gases through the central portion of the absorbent material 36 by directing gaseous flow from an adjacent portion of the absorbent mass 36 toward the perforated portion. The imperforate margin 66 of the retaining wall 44 also serves to reduce channeling of the mixture of gases between the absorbent 36 and the lateral wall 32 of the canister 12.

For use, the disposable absorber 10 should be supported, preferably in an upright position, with the inlet fitting 18 at the top, in order to permit moisture accumulating during operation of the respiratory apparatus to move down the outlet fitting 24 into a conventional breathing bag attached to the outlet fitting 25 serving as a sump. The disposable absorber 10 may be supported in an upright position by means of a conventional ring stand (not shown) having a ring adapted to be closely fitted around the generally cylindrical portion 58 of the lateral wall 32 of the canister 12 such that the marginal flange 56 of the cover 54 of the canister 12 rests upon the ring in order to prevent the disposable absorber 10 from dropping through the ring.

An end portion 70 of the inlet fitting is internally threaded (as shown at 70a) or otherwise adapted for attachment of a conventional pressure gauge (not shown) of the type commonly used in respiratory apparatus. In some instances, a sight valve or some other device may be attached to the end portion 70 of the inlet fitting 18 in like manner. When the end portion 70 of the inlet fitting 18 is not used, it may be plugged as by means of a suitable externally threaded plug (not shown).

An end portion 72 of the outlet fitting 24 is reduced in diameter relative to the remainder of the outlet fitting 72 and if formed with a bead 72a for attachment of a conventional collapsible breathing bag (not shown) of the type commonly used in respiratory apparatus. The breathing bag may be attached by means of a conventional clamping collar (not shown) engaging the end portion 72 of the outlet fitting 24 adjacent the bead 72a.

An inlet check valve fitting 80 is cemented or otherwise integrally attached to the inlet fitting 18 to communicate with the inlet fitting 18 through a valve opening 82 in the lateral wall 84 of the inlet fitting 18. As shown, the fitting 80 is cemented or otherwise integrally attached to a generally tubular flange 18a formed on the inlet fitting 18 at the outer margin of the valve opening 82. The inlet check valve means 22 is arranged to permit gaseous inflow through the fitting 80 and check reverse gaseous outflow through the fitting 80. As shown, the inlet check valve means 22 comprises a crossmember 86, which extends across the flow path through the fitting 80, and a valve member 88, which is made of soft rubber or other flexible resilient material and is supported in the flow path through the fitting 80 by means of the crossmember 86. The valve member 88 has a disc portion 90 which seats against an inwardly facing generally annular valve seat 92 flush with the crossmember 86 in the flow path through the fitting 80, and a stem portion 94, which is disposed axially with respect to the disc portion 90 and is pulled through a suitable opening 96 in the cross member 86. A flared boss 98, which is formed on the stem portion 94 and is spaced from the disc portion 90 approximately by the thickness of the crossmember 86, is adapted to be compressed so as to pass through the opening 96, when the stem portion 94 is pulled through the opening 96. The boss 98 serves to secure the valve member 88 to the crossmember 86. As shown, the valve seat 92 is constituted by a generally annular member 100 formed in one piece with crossmember 86 and cemented or otherwise integrally attached with the fitting 80.

An outlet check valve fitting 110 is cemented or otherwise integrally attached to the outlet fitting 24 to communicate with the outlet fitting 24 through a valve opening 112 in the lateral wall 114 of the outlet fitting 24. As shown, the fitting 110 is cemented or otherwise integrally attached to a generally tubular flange 24a formed on the outlet fitting 24 at the outer margin of the valve opening 112. The outlet check valve means 28 is arranged to permit gaseous outflow through the fitting 110 and to check reverse gaseous inflow through the fitting 110. As shown, the outlet check valve means 28 comprises a crossmember 116, which extends across the flow path through the fitting 110, and a valve member 118, which is similar to the valve member 88 and is supported in the flow path through the fitting 110 by means of the crossmember 116. The valve member 118 has a disc portion 120, which seats against an outwardly facing generally annular valve seat 122 flush with the crossmember 116 in the flow path through the fitting 110, and a stem portion 124, which is disposed axially with respect to the disc portion 120 and is pulled through a suitable opening 126 in the crossmember 116. A flared boss 128, which is formed on the stem portion 124 and is spaced from the disc portion 120 approximately by the thickness of the crossmember 116, is adapted to be compressed so as to pass through the opening 126 when the stem portion 124 is pulled through the opening 126. The boss 128 serves to secure the valve member 118 to the crossmember 116. As shown, the valve seat 122 is constituted by a generally annular member 130 formed in one piece with the crossmember and cemented or otherwise integrally attached within the fitting 110.

A generally tubular infeed fitting 140 is cemented or otherwise integrally attached to the outlet fitting 24 to communicate with the outlet fitting 24 through an infeed opening 142 in the lateral wall 114 of the outlet fitting 24. Preferably the infeed opening 142 is located directly opposite the aforementioned valve opening 112, as shown, in order to facilitate thorough mixing of gases from the infeed fitting 140 with gases from the outlet opening 26.

In preparation of the disposable carbon dioxide absorber 10 for use, suitable connections are made to other parts (not shown) of the respiratory apparatus. As mentioned, a pressure gauge may be attached to the end portion 70 of the inlet fitting 18, and a breathing bag may be attached to the end portion 72 of the outlet fitting 24. Suitable flexible corrugated conduits or the like may be used to connect the inlet check valve fitting 80 and the outlet check valve fitting 110 to a face mask, mouthpiece, trachial insert, or similar breathing appliance, and to connect the infeed fitting 140 to a source of anesthetic or therapeutic gases mixed with oxygen. The carbon dioxide absorber 10 is supported in an upright position, as mentioned, in order to permit the breathing bag to serve as a sump for moisture accumulating during operation of the respiratory apparatus and dripping down the outlet fitting 24.

As mentioned, the disposable carbon dioxide absorber 10 is designed to be used once and then disposed of in order to eliminate the hazards of reinfection and cross-infection attending the repeated use of carbon dioxide absorbers dioxide parts absorbers in respiratory apparatus. Thus, the disposable carbon dioxide absorber 10 may be used to advantage in conjunction with other disposable parts in respiratory apparatus.

In FIGS. 5 and 6 there is shown a disposable carbon dioxide absorber apparatus, indicated generally at 10', embodying the principles of this invention in a modified form. In FIGS. 5 and 6, primed reference numerals are used to indicate parts and features corresponding to like-numbered parts and features in FIGS. 1 through 4.

In the disposable carbon dioxide absorber 10', the inlet end wall 14' of the canister 12', the inlet fitting 18', and the inlet check valve fitting 80' are formed either in one piece, as shown or in two half-sections or otherwise integrally attached together, and the outlet end wall 16' of the canister 12', the outlet fitting 24', and the outlet check valve fitting 110' similarly are formed either in one piece, as shown, or in two half-sections cemented or otherwise integrally attached together. The inner margin of the opening between the inlet fitting 18' and the fitting 80' is flattened so as to constitute the valve seat 92' for the disc portion 90' of the valve member 88' of the inlet check valve means 22'. As shown, the crossmember 86' holding the stem portion 94' of the valve member 88' is formed in one piece with the inlet fitting 18' and the fitting 80'. The outer margin of the opening between the outlet fitting 24' and the fitting 110' is flattened so as to constitute the valve seat 122' for the disc portion 120' of the valve member 118' of the outlet check valve means 28'. As shown, the crossmember 116' holding the stem portion 124' of the valve member 118' is formed in one piece with the outlet fitting 24' and the fitting 110'.

The retaining wall 42' is cemented or otherwise integrally attached to the inlet end wall 14' of the canister 12' at a shouldered portion 140 spaced radially inwardly from the outer margin of the inlet end wall 14' so as to eliminate the need for an imperforate margin on the retaining wall 42'. The retaining wall 44' is cemented to otherwise integrally attached to the outlet end wall 16' of the canister 12' at a shouldered portion 142 spaced radially inwardly from the outer margin of the outlet end wall 16' so as to eliminate the need for an imperforate margin on the retaining wall 44'.

The inlet check valve fitting 80' and the outlet check valve fitting 110' are oriented so as to be declined, as shown, when the disposable carbon dioxide absorber 10' is upright. Such declination of the fittings 80' and 110' facilitates attachment of conduits when the disposable carbon dioxide absorber 10' is attached to an overhead operating room unit or the like. In order to substantially prevent leakage of moisture into the outlet check valve fitting 110', an annular shielding washer 144 is cemented or otherwise integrally attached to the outlet fitting 24' at a shouldered portion 146 between the retaining wall 44' and the fitting 110'. The shielding washer 142 shields the fitting 110' and causes large droplets of moisture to drop to the sump attached to the outlet fitting 24' without running down the outlet fitting 24'.

In other respects, the disposable carbon dioxide absorber 10' of FIGS. 5 and 6 is substantially similar to the carbon dioxide absorber 10 of FIGS. 1 through 4.

Modifications and improvements within the scope of this invention as best defined in the appended claims may be suggested to those skilled in the art.

Claims

We claim:

1. Disposable carbon dioxide absorber apparatus for use in absorbing gaseous carbon dioxide from a mixture of gases in respiratory apparatus, said disposable carbon dioxide absorber apparatus comprising: a canister adapted to contain carbon dioxide absorbent material, said canister having spaced apart inlet and outlet walls and a lateral wall between said inlet and outlet walls; a cover for said canister, said cover being adapted to be attached to one end of said lateral wall; an inlet fitting integrally attached to said inlet wall to communicate with the interior of said canister through an inlet opening in said inlet wall; inlet check valve means arranged to permit gaseous inflow through an inlet valve opening in said inlet fitting and to check gaseous outflow through said inlet valve opening; an outlet fitting integrally attached to said outlet wall to communicate with the interior of said canister through an outlet opening in said outlet wall; outlet check valve means arranged to permit gaseous outflow through an outlet valve opening in said outlet fitting and checking gaseous inflow through said outlet valve opening; retaining means for retaining said absorbent material in spaced relation to the respective inlet and outlet walls, said retaining means including opposed retaining walls integrally attached to the respective inlet and outlet walls within said canister adjacent but spaced from the respective inlet and outlet walls, each retaining wall having a perforated portion adapted to permit gaseous flow therethrough, one of said inlet and outlet walls and the adjacent retaining wall being attached to each other as part of said cover adapted to be attached to said one end of said lateral wall and the other of said inlet and outlet walls and the adjacent retaining wall being attached to the opposite end of said lateral wall; and an infeed fitting integrally attached to said outlet fitting to communicate with said outlet fitting through an infeed opening in the lateral wall of said outlet fitting, said infeed fitting being located between the outlet opening in said outlet wall and said outlet check valve.

2. The disposable carbon dioxide absorber apparatus of claim 1 wherein the retaining wall adjacent said inlet wall has a perforated portion adapted to permit gaseous flow from said inlet opening to said absorbent material and an imperforate portion aligned with said inlet opening and adapted to deflect gaseous flow from said inlet opening toward said perforated portion, and wherein the retaining wall adjacent said outlet wall has a perforated portion adapted to permit gaseous flow from said absorbent material to said outlet opening and an imperforate portion aligned with said outlet opening and adapted to deflect gaseous flow from an adjacent portion of said porous mass toward said perforated portion.

3. The disposable carbon dioxide absorber apparatus of claim 2 wherein each retaining wall further has an imperforate margin.

4. The disposable carbon dioxide absorber apparatus of claim 1 further comprising a generally tubular inlet check valve fitting integrally attached to said inlet fitting to communicate with said inlet fitting through a valve opening in the lateral wall of said inlet fitting, said inlet check valve means being arranged to permit gaseous inflow through said inlet check valve fitting and check gaseous outflow through said inlet check valve fitting.

5. The disposable carbon dioxide absorber apparatus of claim 4 wherein said inlet wall is formed in one piece with said inlet fitting and with said inlet check valve fitting.

6. The disposable carbon dioxide absorber apparatus of claim 1 further comprising a generally tubular outlet check valve fitting integrally attached to said outlet fitting to communicate with said outlet fitting through a valve opening in the lateral wall of said outlet fitting, said outlet check valve means being arranged to permit gaseous outflow through said outlet check valve fitting and to check gaseous inflow through said outlet check valve fitting.

7. The disposable carbon dioxide absorber apparatus of claim 6 wherein said outlet wall is formed in one piece with said outlet fitting and with said outlet check valve fitting.

8. The disposable carbon dioxide absorber apparatus of claim 6 further comprising a generally tubular inlet check valve fitting integrally attached to said inlet fitting to communicate with said inlet fitting through said inlet valve opening being formed in the lateral wall of said inlet fitting and a generally tubular outlet check valve fitting integrally attached to said outlet fitting to communicate with said outlet fitting through said outlet valve opening being formed in the lateral wall of said outlet fitting, said inlet check valve means being arranged to permit gaseous inflow through said inlet check valve fitting and check gaseous outflow through said inlet check valve fitting, said outlet check valve means being arranged to permit gaseous outflow through said outlet check valve fitting and to check gaseous inflow through said outlet check valve fitting.

9. The disposable carbon dioxide absorber apparatus of claim 8 wherein said inlet wall is formed in one piece with said inlet fitting and with said inlet check valve fitting and said outlet wall is formed in one piece with said outlet fitting and with said outlet check valve fitting.

10. Disposable carbon dioxide absorber apparatus for use in absorbing gaseous carbon dioxide from a mixture of gases in respiratory apparatus, said disposable carbon dioxide absorber apparatus comprising: a canister adapted to contain carbon dioxide absorbent material, said canister having spaced inlet and outlet walls; an inlet fitting integrally attached to said inlet wall to communicate with the interior of said canister through an inlet opening in said inlet wall; inlet check valve means arranged to permit gaseous inflow through an inlet valve opening in said inlet fitting and to check gaseous outflow through said inlet valve opening; an outlet fitting integrally attached to said outlet wall to communicate with the interior of said canister through an outlet opening in said outlet wall; outlet check valve means permitting gaseous outflow through an outlet valve opening in said outlet fitting and checking gaseous inflow through said outlet valve opening; and an infeed fitting integrally attached to said outlet fitting to communicate with said outlet fitting through an infeed opening in the lateral wall of said outlet fitting, said infeed fitting being located between the outlet opening in said outlet wall and said outlet check valve.

11. The disposable carbon dioxide absorber apparatus of claim 10 further comprising a generally tubular inlet check valve fitting integrally attached to said inlet fitting to communicate with said inlet fitting through said inlet valve opening being formed in the lateral wall of said inlet fitting and a generally tubular outlet check valve fitting integrally attached to said outlet fitting to communicate with said outlet fitting through said outlet valve opening being formed in the lateral wall of said outlet fitting, said inlet check valve means being arranged to permit gaseous inflow through said inlet check valve fitting and check gaseous outflow through said inlet check valve fitting, said outlet check valve means being arranged to permit gaseous outflow through said outlet check valve fitting and to check gaseous inflow through said outlet check valve fitting.

12. The disposable carbon dioxide absorber apparatus of claim 11 wherein said inlet wall is formed in one piece with said inlet fitting and with said inlet check valve fitting and said outlet wall is formed in one piece with said outlet fitting and with said outlet check valve fitting.

13. The disposable carbon dioxide absorber apparatus of claim 11 wherein said infeed opening is located directly opposite said outlet valve opening in the lateral wall of said outlet fitting.

14. The disposable carbon dioxide absorber apparatus of claim 1 wherein said inlet wall and the adjacent retaining wall together form part of a detachable cover for said canister.

15. Disposable carbon dioxide absorber apparatus for use in absorbing gaseous carbon dioxide from a mixture of gases in respiratory apparatus, said disposable carbon dioxide absorber apparatus comprising a generally cup-shaped member adapted to contain carbon dioxide absorbent material and a cover for said generally cup-shaped member;

said generally cup-shaped member including a lateral wall, spaced apart outer and inner walls attached to one end of said lateral wall, said inner wall serving to retain said absorbent material in spaced relation to said outer wall and having a perforated portion adapted to permit gaseous flow therethrough, a fitting attached to said outer wall to communicate with the space between said outer and inner walls through an opening in said outer wall, and check valve means permitting gaseous flow in one direction into said fitting and checking gaseous flow in the opposite direction into said fitting;

said cover being adapted to be attached to the opposite end of the lateral wall of said generally cup-shaped member and including spaced-apart outer and inner walls attached to each other as part of said cover, said inner wall serving to retain said absorbent material in spaced relation to said outer wall and having a perforated portion adapted to permit gaseous flow therethrough, a fitting attached to said outer wall to communicate with the space between said outer and inner walls through an opening in said outer wall, and check valve means permitting gaseous flow in one direction through said fitting and checking gaseous flow in the opposite direction through said fitting; the respective check valve means being so arranged that the direction of permitted gaseous flow into the fitting of said cover is opposite the direction of permitted gaseous flow into the fitting of said generally cup-shaped member, when said cover is attached to said opposite end of the lateral wall of said generally cup-shaped member, to permit one-way gaseous flow through said generally cup-shaped member.

16. The disposable carbon dioxide absorber apparatus of claim 15 wherein each inner wall has an imperforate portion aligned with the opening in the associated outer wall.

17. The disposable carbon dioxide absorber apparatus of claim 16 wherein each inner wall further has an imperforate margin.

18. The disposable carbon dioxide absorber apparatus of claim 15 wherein the check valve means of said generally cup-shaped member permits gaseous outflow from the fitting of said generally cup-shaped member and checks gaseous inflow to the same fitting and wherein the check valve means of said cover permits gaseous inflow from the fitting of said cover and checks gaseous outflow from the same fitting.