Mask for adminstering an anesthetic gas to a patient

A mask for administering gas to a patient in which an inner cup-shaped wall fits over the nose of a patient and engages the face of the patient. An outer wall of the mask is detachably secured to and spaced from the inner wall to form an exhaust passage for the removal of gas exhaled by the patient. A floating disc valve is opened and closed by the exhaling and inhaling of the patient to control the flow of exhaust gas from the gas chamber of the inner wall to the exhaust passage. A valve seat of the floating disc valve is part of the inner wall and a flexible floating valve disc of the floating disc valve is attached to the valve seat. Formed in the peripheral edge of the inner wall is a recessed, V-shaped section to accommodate the middle of the nose and to form a seal against gas leakage.

BACKGROUND OF THE INVENTION 
The present invention relates in general to masks for the administering of 
anesthetic gas to a patient, and more particularly to a mask suitable for 
the administration of anesthetic gas to a dental patient. 
Heretofore, it was the general practice for dentists to use the same mask 
on a plurality of patients for the administration of anesthetic gas. Such 
practices were of concern to the dentist, as well as the patient, because 
of the possibility of cross-contamination. In certain instances, the 
entire dental mask was intended for single patient use. 
In the Glenn E. Brown U.S. Pat. No. 4,015,598, issued on Apr. 5, 1977, for 
Anaesthesic System, there is disclosed a mask for the administration of 
anesthetic gas to a dental patient. The mask comprises an inner cup-shaped 
wall to fit over the nose or the mouth of a patient. The inner wall 
engages the face of the patient along the peripheral edge of the inner cup 
to form a gas chamber between the face of the patient and the inner 
surface of the inner wall. An outer cup-shaped wall was secured to and 
spaced from the inner wall to form an exhaust passage between the inner 
and outer walls. The exhaust passage communicates with the gas chamber 
when the patient exhales. The peripheral edge of the outer wall is 
disposed in the vicinity of the peripheral edge of the inner wall to draw 
into the exhaust passage gas leaking between the face of the patient and 
the inner wall. Gas is introduced into the chamber to be inhaled by the 
patient. A valve is interposed between the inner and outer walls and is 
opened to permit exhaust gas to flow into the exhaust passage from the gas 
chamber when the patient exhales. When the patient inhales, the valve is 
closed blocking the passage of gas from the gas chamber to the exhaust 
passage. 
The Czajka U.S. Pat. No. 4,219,020, issued on Aug. 26, 1980, for Scavenger 
Valve Attachment For Inhalation Sedation System Mask, discloses a 
scavenging attachment mounted on a face mask. An exhalation aperture leads 
through a floating disc check valve to a vacuum chamber which extends in a 
generally concave inverted saucer configuration over and around the mask. 
The vacuum chamber communicates with the surrounding atmosphere by means 
of an annular aperture in order to scavenge from the atmosphere adjacent 
the patient's face any gas escaping from the periphery of the mask. 
MDT McKesson has sold a Twin-Trac Scavenging Mask having a disposable 
safety seal that was removably attached to the perimeter of the mask and 
engageable with the face of the patient. The tubing connecting the mask is 
adjustable by normal movement to accommodate patient position and 
movement. Additionally, the entire unit is heat and steam sterilizable 
including the tubing by well-known and conventional procedures. 
In the Brekke et al. U.S. Pat. No. 4,151,843, granted on May 1, 1979, for 
Apparatus For Administration Of A Gas To A Human And The Exhausting 
Thereof, there is disclosed a mask for the administration of anesthetic 
gas to a patient in which the mask thereof is hollow and covers the entire 
nose. The mask terminates in two projections on its inner surface which 
engage the external portion of the nasal orifices bilaterally, thereby 
preventing leakage of gases out of or into the system at that point. 
The Myers U.S. Pat. No. 3,721,239, issued on Mar. 20, 1973, for Anesthetic 
Gas Exhaust System, discloses an exhaust system for removal of anesthetic 
gas from an operating theatre. The manifold for the system has tubing 
attached thereto and is connected to the suction system. Attached to an 
end of the tubing is a corrugated hose which is flexible and which is 
corrugated in a bellow fashion. 
The McKesson U.S. Pat. No. 1,632,449, issued on June 14, 1927, for a Mask, 
discloses a mask that fits over the nose of a patient for the 
administering of anesthetic gas. The mask includes an elastic flap that 
extends inwardly from the mask opening. 
In the Bartlett, Jr. et al. U.S. Pat. No. 3,395,701, issued on Aug. 6, 
1968, for End Tidal Sampler For An Oxygen Breathing Mask, there is 
disclosed a standard oxygen mask. The upper portion of the mask has an 
inwardly directed section that appears it may fit over the entire nose of 
the user. 
Accutron of Phoenix, Arizona has manufactured and sold a dental mask with a 
valve. The single cup-shaped wall mask has a valve seat with openings 
formed therein as part of the single cup-shaped wall. The valve includes a 
valve disc that normally covers the openings by seating against the valve 
seat to close the valve. When the patient exhales, the valve disc is 
displaced from the valve seat to open the valve. The gas chamber of the 
dental mask communicates with an exhaust system through the opened valve. 
The valve disc is axially attached to the valve seat at the hub thereof. 
SUMMARY OF THE INVENTION 
A mask for administering gas to a patient in which an inner cup-shaped wall 
fits over the nose or mouth of a patient and engages the face of the 
patient. The inner wall forms a gas chamber. An outer wall of the mask is 
detachably secured to and spaced from the inner wall to form an exhaust 
passage for the removal of gas exhaled by the patient. Gas inlet means is 
supported by the outer wall and is detachably secured to the inner wall 
for introducing gas into the gas chamber to be inhaled by the patient. 
Exhaust gas outlet means is supported by the outer wall and communicates 
with the exhaust passage for removing exhaust gas from the exhaust 
passage. Interposed between the inner and outer walls is a floating valve 
disc made of a flexible rubber or plastic that forms a floating disc valve 
with a valve seat of the inner wall. When the patient inhales, the 
floating disc valve is closed to prevent communication between the gas 
chamber and the exhaust passage. When the patient exhales, the floating 
disc valve is opened for the exhaled gas to enter the exhaust passage. 
An object of the present invention is to minimize cross-contamination that 
may be present in the use of a mask by a plurality of patients in the 
administration of anesthetic gas. 
A feature of the present invention is the provision of a multiple wall mask 
in which the inner wall of the mask contacting the face of the patient and 
the valve are detachable from an outer wall of the mask with facility so 
as to be disposable while retaining the outer wall and its attachments for 
reuse. 
Another feature of the present invention is the provision of a multiple 
wall mask in which the inner wall of the mask contacting the face of the 
patient and the valve are detachable from an outer wall of the mask with 
facility for sterilization while retaining the outer wall and its 
attachments for reuse. 
Another feature of the present invention is the contour of an inner wall of 
a mask at a location at which the inner wall engages a center section of 
the nose of the patient to form a tight seal over the center of the nose 
while enabling the mask to be spaced from the eyes of the patient. 
Another feature of the present invention is the floating valve disc is made 
of a soft flexible rubber or plastic and is interposed between the outer 
wall and the inner wall of the mask to control the flow of exhaled gas 
between the gas chamber and the exhaust passage.

DESCRIPTION OF A PRIOR ART MASK 
Illustrated in FIGS. 1, 1A and 1B is a prior art mask 10 comprising an 
inner wall 11 having a generally cup-shaped configuration. The inner wall 
11 is made of a soft, flexible rubber or plastic and fits over the nose or 
mouth of a patient for the administration of gas. Secured to and spaced 
from the inner wall 11 is an outer wall 12 that forms with the inner wall 
11 an exhaust passage 15 therebetween. 
The perimeter of the inner wall 11 engages the face of the patient. The 
inner wall 11 forms a gas chamber 16 confronting the face of the patient. 
Inlet tubes 20 and 20a are supported by the outer wall 12. Disposed within 
the inlet tubes 20 and 20a are rigid plastic conduits 21 and 22 which 
communicate with the gas chamber 16 to introduce an anesthetic gas into 
the gas chamber 16 to be inhaled by the patient. At the end of the 
conduits 21 and 22 are flanges 21a and 22a, respectively, which abut 
against the inner surface of the inner wall 11. While the conduits 21 and 
22 can be detached from the inner wall 11, it cannot be accomplished with 
facility. 
Exhaust tubes 25 and 26 are supported by the outer wall 12. Within the 
exhaust tubes 25 and 26 are rigid exhaust conduits 27 and 28, 
respectively, which communicate with the exhaust passage 15. A source of 
vacuum draws exhaust gas from the exhaust passage 15. Supported by the 
inner wall 11 at the apex of the inner wall 11 and confronting the opening 
of the gas chamber 16 is a floating disc valve 30 made of rigid plastic 
material. The floating disc valve 30 is partially disposed between the 
inner wall 11 and the outer wall 12 for controlling the passage of exhaust 
gas between the gas chamber 16 and the exhaust passage 15. The entire 
floating disc valve 30 is separable from the inner wall 11 including the 
rigid valve seat with the openings therein. 
When the patient inhales, the floating disc valve 30 closes the opening in 
the inner wall 11 between the gas chamber 16 and the exhaust passage 15. 
At that time, the patient inhales the anesthetic gas introduced into the 
gas chamber 16. When the patient exhales, the floating disc valve 30 opens 
the opening between the inner wall 11 and the exhaust passage 15 so that 
the exhaust gas is drawn from the gas chamber 16 into the exhaust passage 
15 by the source of vacuum. The perimeter of the outer wall 12 is in the 
general vicinity of the perimeter of the inner wall 11. Any gas escaping 
from the mask 10 between the face of the patient and the mask 10 is 
scavenged into the exhaust passage 15 and removed therefrom by the source 
of vacuum. 
DESCRIPTION OF THE PREFERRED EMBODIMENT 
Illustrated in FIGS. 2-6 is a mask 35 embodying the present invention for 
administering anesthetic gas to a patient. In the exemplary embodiment, 
the mask 35 fits over the nose of the patient. Masks of this nature are 
adapted to fit over the mouth or nose of a patient. 
The mask 35 comprises an inner cup-shaped wall 36 made of a soft, flexible 
rubber or plastic, such as silicone rubber. The perimeter 36a of inner 
wall 36 is folded over in the inward direction. When the mask 35 is placed 
over the nose of the patient, the perimeter 36a of the inner wall 36 
engages the face of the patient. The perimeter 36a of the inner wall 36 
serves to provide an improved seal between the inner wall 36 and the face 
of the patient. The inner wall 36 forms a gas chamber 40 confronting the 
face of the patient. In the exemplary embodiment, openings 41 and 42 are 
formed in the inner wall 36 for the introduction of anesthetic gas into 
the gas chamber 40. At the upper, central portion of the perimeter 36a of 
the inner wall 36 is formed an inwardly directed, generally V-shaped 
recessed area 37 to accommodate the center of the nose of the patient. The 
surfaces forming the generally V-shaped area 37 are directed toward the 
gas chamber 40 and form a tight seal over the center of the nose while 
enabling the mask 35 to maintain a spaced relation relative to the eyes of 
the patient. The configuration of the perimeter 36a forming the recessed 
area 37 is adaptable to conform to the shape of the center of the nose of 
the patient. The mask 35 is kept away from the eyes of the patient for 
safety reasons and still forms an effective seal between the inner wall 36 
of the mask 35 and the face of the patient. 
Supported by the inner wall 36 and spaced therefrom is an outer wall 45. 
The outer wall 45, in the exemplary embodiment, is made of flexible rubber 
or plastic, such as silicone rubber. Spacers or ribs 46 are formed on the 
outer wall and confront the inner wall 36 to maintain a spaced relation 
between the inner wall 36 and the outer wall 45. The space between the 
inner wall 36 and the outer wall 45 forms an exhaust passage 47. Openings 
45a and 45b are formed in the outer wall 45 for exhaust gas to be removed 
from the exhaust passage 47 by a suitable source of vacuum, not shown. 
In the exemplary embodiment, integrally formed with the outer wall 45 are 
gas inlet tubes 50 and 51. Integrally formed with the outer wall 45, in 
the exemplary embodiment, are exhaust tubes 52 and 53. The tubes 50-53 are 
made of flexible rubber or plastic with corrugated configurations for 
improved flexibility in positioning the hoses connected to the tubes 
50-53. 
Disposed within the gas inlet tubes 50 and 51 are rigid conduits 60 and 61, 
respectively. The rigid conduits 60 and 61 are made of a suitable rigid 
plastic and provide a tight fitting engagement with the interior walls of 
the associate tubes 50 and 51. The conduits 60 and 61 extend into the gas 
chamber 40 via the openings 41 and 42, respectively, of the inner wall 36. 
At the end of the conduit 60, that is received by the opening 41, are 
radially spaced annular flanges 62 and 63. The inner wall 36 is disposed 
between the flanges 62 and 63 in sealing engagement with the conduit 60 
for anesthetic gas to be introduced into the gas chamber 40. The inlet 
tube 50 is disposed in a tight fitting sealing engagement with the conduit 
60. By means of the double flanges 62 and 63 of the conduit 60, the inner 
wall 36 is removably secured to the conduit 60 and facilitates the removal 
of the inner wall 36 from the outer wall 45. 
At the end of the conduit 61, that is received by the opening 42, are 
radially spaced annular flanges 64 and 65. The inner wall 36 is disposed 
between the flanges 64 and 65 in sealing engagement with the conduit 61 
for anesthetic gas to be introduced into the gas chamber 40. The inlet 
tube 51 is disposed in a tight fitting sealing engagement with the conduit 
61. By means of the double flanges 64 and 65 of the conduit 61, the inner 
wall 36 is removably secured to the conduit 61 and facilitates the removal 
of the inner wall 36 from the outer wall 45. 
Integrally formed with the inner wall 36 is an annular valve seat 70 with a 
hub 70a, spokes 70b and sectors 70c in the form of openings. Disposed 
between the valve seat 70 of the inner wall 36 and the outer wall 45 is a 
floating valve disc 75. The valve seat 70 and the floating valve disc 75 
form a floating disc valve 76. The floating disc valve 76 is made of a 
soft flexible rubber or plastic, such as silicone rubber. The floating 
valve disc 75 is secured to or otherwise caused to adhere to the hub 70a 
of the valve seat 70. The floating valve disc 75 is coextensive with the 
valve seat 70 and is interposed between the valve seat 70 and the outer 
wall 45. 
Normally, the floating valve disc 75 is in sealing engagement with the 
valve seat 70 to close the opening sectors 70c by virtue of its securement 
to the hub 70a of the valve seat 70. When the floating valve disc 75 is in 
sealing engagement with the valve seat 70, the gas chamber 40 does not 
communicate with the exhaust passage 47 since the sectors 70c are closed. 
When the patient inhales, the floating valve disc 75 is in sealing 
engagement with the valve seat 70 and the opening sectors 70c are closed 
to prevent exhaust gas from entering the gas chamber 40 and to prevent 
anesthetic gas introduced into the gas chamber 40 from escaping into the 
exhaust passage 47. When the patient exhales, the floating valve disc 75 
is radially displaced from the valve seat 70 and exhaust gas in the gas 
chamber 40 enters the exhaust passage 47 via the opening sectors 70c of 
the valve seat 70. A suitable source of vacuum, not shown, continuously 
removes exhaust gas from the exhaust passage 47 via the tubes 52 and 53. 
In the exemplary embodiment, the perimeter of the outer wall 45 is disposed 
in the general vicinity of the perimeter 36a of the inner wall 36. In the 
event of leakage of anesthetic gas or exhaust gas between the inner wall 
36 and the face of the patient, the source of vacuum draws the leaking gas 
into the exhaust passage 47 and removes the leaking gas from the exhaust 
passage 47 into the exhaust tubes 52 and 53. 
By virtue of the present invention, the inner wall 36 with the floating 
disc valve 76 can be removed from the outer wall 45 with greater facility. 
The inner wall 36 with the floating disc valve 76 can be replaced by an 
unused inner wall 36 with a floating disc valve 76, or the inner wall 36 
with the floating disc valve 76 can be removed and sterilized in a 
conventional manner for reuse.