Patent Publication Number: US-2009235932-A1

Title: Respiratory face mask and breathing circuit assembly

Description:
RELATED APPLICATIONS 
     The present application is a continuation-in-part (CIP) of my prior copending U.S. patent application Ser. No. 12/221,379; filed Aug. 8, 2008, which in turn is a continuation-in-part (CIP) of my copending prior application Ser. No. 11/809,435; filed Jun. 1, 2007 (herein “prior applications”). The aforesaid prior applications hereby are incorporated herein and made part hereof by this reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present application relates generally to devices for delivering respiratory gas or gases in medical applications, and more particularly, to a new and improved respiratory face mask and breathing circuit assembly that is especially useful in administering gases, such as anesthesia inhalation agents, or oxygen, or air, or mixtures of same, for medical purposes, and as such represents an improvement over the similar device or devices disclosed in my prior applications. 
     2. Description of the Prior Art 
     In my prior applications, I fully disclose a disposable anesthesia face mask assembly having a flexible hollow inflatable sealing cushion extending along substantially the entire peripheral edge of the mask shell or body member to prevent anesthesia gas or the like delivered through the gas portal on the mask from escaping and adversely affecting the surgical environment. The unique face mask assembly disclosed in my prior applications represents a significant advance over the prior art because, inter alia, it is the only respiratory or anesthesia mask now known having a pneumatic sealing cushion that extends over and under the chin portion of the patient&#39;s face and surprisingly, as a result of this unique arrangement, requires only a relatively simple single headstrap or band for maintaining the mask in a stable position even during long duration surgical procedures. Hence, the mask and headstrap assembly of my prior applications are ideally suited for use during so-called “sedation” anesthesia procedures where the patient breathes on its own. 
     A well-known safe and effective sedation anesthetic in gas inhalation form is nitrous oxide (N 2 O). This compound, frequently called “laughing gas” or “happy gas,” has been used medically for many years usually as an analgesic or “light sedative” to ease pain associated with trauma, childbirth or heart attacks, for example, or as a carrier for more potent anesthesia gases (e.g. Desflurane, Sevoflurane). Indeed, nitrous oxide is so safe, easy to handle, and readily available relatively inexpensively, it has been used as an anesthetic in dentistry since the 1800s. When used by a dentist, nitrous oxide is typically administered through a demand-valve or continuous inhaler placed over the patient&#39;s nose so that the patient&#39;s mouth can be worked on while the patient continues to inhale the gas. A full face-mask therefore cannot be used in dentistry, and to avoid build-up of exhaled or waste nitrous oxide, which can pose an intoxicating and prolonged-exposure hazard to the clinic staff in the room where the procedure is being conducted, a continuous-flow-fresh-air ventilation system or nitrous-scavenging system must be used. 
     In “ Case Series of Nurse - Administered Nitrous Oxide for Urinary Catheterization in Children,” Anesthesia  &amp;  Analgesia  2007, 104:876-879, Judith L. Zier, M D. et al, the authors reported the use N 2 O to “sedate” children undergoing a painful procedure in a hospital setting. Administration of the nitrous was carried out using commercially available “dental” equipment to supply the N 2 O gas and to scavenge exhaled waste (through a nose mask). Thus, the authors reported that a “comfortable seal could be maintained . . . over the nose of the older child” (emphasis added). Nitrous oxide is only minimally metabolized in the human body. Accordingly, unless provision is made to collect or otherwise scavenge the breath of a patient exhaled through the mouth, build up of exhaled N 2 O waste gas in the hospital environment using such “dental equipment” cannot reasonably be avoided. 
     In order to overcome the foregoing disadvantages, the present application discloses a new and improved respiratory face mask and breathing circuit assembly adapted to be used with commercially available nitrous oxide gas handling equipment commonly and heretofore used in “dentistry.” When so employed, the respiratory face mask and breathing circuit assembly of the present invention completely avoids contaminating the surrounding environment with built-up waste N 2 O gas thereby facilitating safe and effective “combined” use of such equipment for “sedation” purposes in a hospital or other clinical environment. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention, briefly described, essentially comprises the respiratory face mask of my prior applications improved by a supplemental unique breathing circuit enabling the face mask to be seamlessly coupled to a conventional “dental” nitrous gas set-up having a fresh-gas-supply module and a vacuum or scavenging module. The unique breathing circuit includes at one end a plug for insertion within the main gas flow passage of the mask. A fresh-gas, flexible supply tube is joined to the breathing circuit plug at one end and is adapted to be coupled to the outlet nozzle on the fresh gas supply module of the “dental” set-up. At the other or opposed end of the breathing circuit, a collapsible, flexible gas reservoir bag is suitably provided. The bag&#39;s distal end is joined to one end of a gas flow compensator which, in turn, has extending from its other opposed end a flexible tube suitably adapted to be coupled to the vacuum module of the “dental” set-up. When so arranged, the face mask, breathing circuit including the gas flow compensator of the present invention permits fresh gas supplied from the “dental” set-up to be inhaled continuously by a patient being “sedated” and any and all exhaled waste gas whether expelled through the patient&#39;s nose or mouth is safely scavenged through the vacuum module of the “dental” setup thereby avoiding re-breathing of exhaled gas by the patient and any build-up of waste N 2 O gas in the surrounding environment. 
     There has thus been described, rather broadly, several important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims attached. 
     In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting. 
     As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     It is therefore an object of the present invention to provide a new and improved respiratory face mask and breathing circuit assembly which has all of the advantages of the prior art and none of the disadvantages. 
     It is another object of the present invention to provide a new and improved face mask and breathing circuit that is especially suitable for use in administering anesthesia inhalation gas or gases to a patient continuously without causing any exhaled waste gas to build-up in the surrounding area. 
     It is further object of the present invention to provide a new and improved face mask and breathing circuit assembly which is of durable and reliable constructions. 
     An even further object of the present invention is to provide a new and improved respiratory face mask and breathing circuit assembly which is susceptible of a low cost of manufacture with regard to both materials and labor, and which accordingly is then susceptible of low prices of sale, thereby making such a face mask and breathing circuit assembly economically available to the medical community. 
     Even still another object of the present invention is to provide a new and improved respiratory face mask and breathing circuit assembly that may be used on a patient before, during or after surgery in a safe and efficient manner. 
     It is yet another object of the present invention to provide a new and improved respiratory face mask and breathing circuit assembly where the breathing circuit is adapted to be coupled to the fresh gas supply module of a nitrous oxide “dental set” and further includes means for connecting the breathing circuit to the vacuum module of the same “dental set.” 
     Still yet another object of the present invention is to provide a new and improved respiratory face mask and breathing circuit assembly where the breathing circuit is adapted to be coupled to the fresh gas supply module of a nitrous oxide “dental set” and further includes means for automatically preventing re-breathing of waste gas exhaled into said breathing circuit. 
     Yet still yet another object of the present invention is to provide a new and improved respiratory face mask and breathing circuit assembly where the breathing circuit is adapted to be coupled to the fresh gas supply module of a nitrous oxide “dental set” and further includes a gas flow compensator for substantially avoiding re-breathing of gas exhaled into the breathing circuit by the patient. 
     Another object of the present invention is to provide a new and improved respiratory face mask characterized by at least two primary components, namely a cup-like shell or receptacle member terminating at its peripheral edge in a peripheral flange, and an annular substantially donut-shaped hollow inflatable cushion or sealing member affixed or otherwise permanently attached to the flange along substantially the flange&#39;s entire peripheral extent, in combination with a breathing circuit adapted to be coupled between the cup-like shell member and a device for supplying anesthesia gas normally used in dentistry. 
     Even still yet another object of the present invention is to provide a disposable anesthesia face mask and breathing circuit assembly ideally suited for use during “sedation” anesthesia procedures where the patient is self-breathing. 
     These together with other objects of the invention, along with the various features of novelty which characterize the invention, are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated preferred embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein: 
         FIG. 1  is a schematic perspective view of the respiratory face mask and breathing circuit assembly of the present invention where the mask is depicted fitted to a patient and being connected to the fresh gas supply module and vacuum module, respectively, of an anesthesia gas supply and scavenging device. 
         FIG. 2  is an enlarged cross-sectional view in elevation of a portion of the respiratory face mask and breathing circuit assembly of  FIG. 1  taken along line  2 - 2  of  FIG. 3  (i.e. element  62 ). 
         FIG. 3  is a cross-sectional view taken along line  3 - 3  in  FIG. 2 . 
         FIG. 4  is an assembly view of the various parts making up the respiratory face mask and breathing circuit assembly of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference now to  FIGS. 1-4  of the Drawings, there is shown a preferred embodiment of the new and improved respiratory face mask and breathing circuit assembly of the present invention generally comprising a face mask  10 , a breathing circuit  12 , and a gas supply and scavenging device  14 . 
     As schematically depicted in  FIG. 1 , face mask  10  is fitted on the face of a patient  16  via a headstrap  18  (preferably elastic) removably attachable to the face mask via anchors or the like on the opposed edges thereof. The headstrap helps to stabilize the mask on the face and head of a person, preferably before, during and/or after surgery. Many of the details of construction of the face mask  10  and headstrap  18  are outside the scope of the present invention. For a more detailed understanding of same, the interested reader is directed to my prior applications (incorporated herein by reference). Suffice it to say for purposes of fully understanding the present invention, face mask  10  preferably is similar to that fully disclosed in my prior applications and therefore, comprises a cup-like shell or receptacle member  20  and a flexible pneumatic (inflatable) cushion member  22 . The flexible pneumatic inflatable cushion member  22  defines a generally donut-shaped sealing member extending annually along the entire extent of a peripheral rim or flange  24  defined by the shell member  20 . 
     As further disclosed in my prior applications, the crown portion of shell member  20  has a first cylindrical hollow inlet member or port  26  suitably sized to removably receive in snug sliding (and sealing) engagement therein the nipple of a conventional breathing circuit and to define a passageway such that anesthesia gas or other gases are adapted to pass from a source through the breathing circuit and the passageway into the interior of shell member  20 . The breathing circuit also is adapted to receive returned or exhaust gas or gases through the same passageway and convey such exhausted gas or gases to a conventional gas evacuation or scavenging apparatus such as is provided on a standard anesthesia machine used in surgery rooms. Shell member  20  also may include a second cylindrical hollow outlet member or port  28  for connection to a length of flexible tube (not shown) the other or distal end of which is adapted suitably to be connected to a conventional CO 2  monitoring device or capnograph for sensing end-tidal CO 2  of a breathing patient. 
     As further disclosed in my prior applications, when the face mask  10  is applied to the face of a patient, the top portion of the mask receives and covers the nose portion of the patient, the intermediate portion of mask covers the mouth portion of the patient, and the bottom or widest portion of the mask receives and engages the underside of the chin and jaw portion of the patient&#39;s face with the pneumatic cushion member  22  effectively serving to seal the periphery of the mask relative to the patient&#39;s face and preventing escape of anesthesia gas or other gas into the surrounding environment notwithstanding the irregular contour of the patient&#39;s face. As further disclosed in my prior applications, the foregoing engagement between the underside of the chin or jaw portion of the patient with the bottom or widest transverse edge portion of the mask prevents displacement of the mask toward the ocular area, helps to keep the patient&#39;s mouth closed, and securely stabilizes the mask assembly on the face when the elastic headstrap is used thereby freeing both hands of attending anesthesia personnel for use elsewhere. It will be appreciated in connection with carrying out the present invention, that the face mask  10 , depicted in  FIG. 1 , can be fitted to the face and head of a patient in the foregoing manner, or in the manner described in my prior applications. 
     In accordance with the present invention, and as schematically depicted in  FIG. 1 , a uniquely modified breathing circuit  12  is employed to deliver anesthesia gases or the like originating from gas supply and scavenging device  14  to face mask  10 . Device  14  is of the well-known type commonly used in the practice of dentistry and comprises inter alia a fresh gas supply module  30  and a vacuum module  32  for scavenging waste gas or exhaled gas. By way of example, such devices are commercially available from Porter Instrument, Hatfield, Pa. 19440 and now are in widespread use. Thus, as is well known, the gas supply module  30  in such “dental” devices is adapted to supply both nitrous oxide and oxygen and has valve controls for adjusting the flow of each to produce a mixture of any desired concentration. The scavenging module  32  provides a source of negative pressure (vacuum) and can be wall mounted to provide a convenient outlet. It will be understood that the constructional details of these devices are conventional and outside the scope of the present invention. 
     Modified breathing circuit  12  includes a Y-connector  34  having a first tubular plug or nipple  36  suitably sized for mating engagement within the first cylindrical inlet member or port  26  on face mask  10 . Y-connector  34  also features a second tubular branch or nipple  38  for mating with a first open cylindrical end  40  of flexible corrugated tube  42  and a third tubular branch or receptacle  44  for mating with a first tubular end or nipple  46  of elbow connector  48 . The second or opposed end  50  of elbow connector  48  is adapted to be connected to a flexible “fresh gas” supply tube  52  which in turn is connected to the output of the gas supply module  30  of “dental” gas supply and scavenging device  14 . ( FIG. 1 ). 
     Flexible corrugated tubing  42  terminates in a second open end  54  which in turn is adapted to be matingly engaged with the first cylindrical open end  56  of flexible collapsible reservoir bag  58 . The opposed second cylindrical end of reservoir bag  58  terminates in a cylindrical plug  60  having a rotatable gate valve therein (not shown) controlled by handle  61 . Rotation of handle  61  in either direction about the central longitudinal axis of the plug  60  varies the size of a suitable opening provided in the distal end of plug  60  between a minimum and a maximum extent, respectively. The purpose of the gate valve is to adjust the flow of exhaled waste gas through the reservoir bag  58  somewhat if desired as will be made more evident below. 
     Thus far breathing circuit  12  is similar to a prior art Modified Jackson Rees (MJR) breathing circuit used in General Anesthesia applications. In order to adapt breathing circuit  12  for purposes of the present invention, the cylindrical plug  60  located on the second end of reservoir bag  58  is operatively coupled to a gas flow compensator  62  the purpose of which is to automatically assure that any waste gas exhaled into the breathing circuit will not be re-breathed by the patient, or escape into the surrounding environment, but rather will safely be evacuated via the vacuum module  34  of gas supply and scavenging device  14 . Gas flow compensator  62  generally is tubular in shape and has a first end defining a cylindrical receptacle  64  for receivingly mating with plug  60 . The opposed second end of compensator  62  defines a cylindrical opening  66  exposed to the surrounding environment. 
     Alternatively, gas flow compensator  62  may advantageously be integrated with plug  60  to form a one-piece or unitary construction. In such a case, the gate valve and its handle  61  is obviated and may be may dispensed with if desired. 
     Mounted interiorly of compensator  62  substantially medially of the first and second opposed ends thereof and coaxially therewith is a nozzle  68  of reduced diameter relative to both receptacle  64  and opening  66  substantially as shown in  FIGS. 2 and 3 . Nozzle  68  preferably is supported at its leftmost end ( FIGS. 2 and 3 ) by a series of four radial struts  70  which serve as a spider suspending the nozzle in its coaxial orientation, but which allow a quantity of air from the environment to pass through opening  66  from the right to the left, thence through the openings in the spider as indicated by arrows  72 , before entering nozzle  68  through the latter&#39;s leftmost open side as viewed in  FIG. 2 . A length of flexible tubing  76  is suitably securely affixed to nozzle  68  ( FIG. 2 ) proximal to struts  70  and extends coaxially therefrom out through open end  66  of the compensator  62  ultimately being connected at its other opposed distal end to vacuum module  32  of “dental” device  14 . It will be noted that the length or axial extent of nozzle  68  is not critical, and it suffices if this part has an axial extent or length sufficient to provide a firm gripping surface for the end of tube  76  attached thereto. 
     By the foregoing arrangement of parts, it will be appreciated that any exhaled waste gas entering receptacle  64  from reservoir bag  58  (arrows  79 ,  FIG. 2 ) as well as a quantity of outside air entering compensator  62  (arrows  72 ) will be drawn by the vacuum in flexible tube  76  through the left side of nozzle  68  and scavenged by vacuum module  32  of device  14 . Compensator  62  thus automatically compensates for any dead space in the breathing circuit which might cause exhaled waste gas in the reservoir bag  58  or in the flexible corrugated tubing  42  to stagnate therein and be re-breathed by a patient. Because the face mask  10  has a sealing cushion, leakage of any gas whatsoever into the surrounding environment also is avoided. 
     Optionally, a cylindrical extension sleeve  80  can be attached to the rightmost side of compensator  62  to increase the effective axial extent of the compensator and thereby form a supplemental reservoir for any exhaled waste gas that may travel along a path from bag  58  through plug  60  and pass beyond the leftmost side of nozzle  68 . Further tweaking of the flow of gases through the gas flow compensator  62  may optionally be attempted by adjusting the position of the handle  61  of the gate valve on the plug  60 , but generally this valve should be placed in the fully “open” position during operation of the disclosed apparatus. Here too, if desired, extension tube  80  and the rightmost end of compensator  62  may be formed of a unitary one-piece construction. 
     In using the apparatus of the invention, and as schematically shown in  FIG. 1 , it will be seen that fresh gas is adapted to be supplied from supply module  30  on “dental” device  14  to the patient through supply tube  52 , Y-connector  34 , and mask inlet port  26  (arrow  82 ). Waste or exhaled gas flows into corrugated tube  42  and reservoir bag  58  under the influence of the vacuum module  32  applying a negative pressure in tube  76  (arrows  79 ). All that is necessary after fitting mask  10  to the face of a patient is to flush (expand) the bag  58  with a fresh supply of gas from supply module  30  of device  14  through supply tube  52  (using the “flush” button on the fresh gas supply module), attach the breathing circuit Y-connector  34  to the mask inlet, and connect the flexible vacuum tube  76  from the gas flow compensator  62  to the outlet of vacuum module  32 . The patient then will breath easily through mask  10  and in so doing draw fresh gas from tube  42  and the flushed reservoir bag  52 , collapsing the bag. When the patient exhales, the waste gas will fill the bag (and corrugated tube  42 ) and be immediately drawn through the gas flow compensator  62  via the negative pressure afforded by vacuum tube  76 . At the same time, the negative pressure in tube  76  will cause fresh gas from supply tube  52  to fill corrugated tube  42  and reservoir bag  58  so as the patient breathes again, the patient avoids re-breathing any waste or exhaled gas. 
     From the foregoing description, it should be evident that the apparatus of the present invention solves the vexing problem of providing a face mask for administering anesthesia gases or other gases employing the relatively portable and inexpensive gas supply and scavenging equipment heretofore used only in the practice of dentistry. By using the face mask of the present invention, with its excellent sealing capability, and the modified breathing circuit according to the present invention, in conjunction with such “dental” devices, re-breathing of waste gas by the patient and build-up of waste gas in the clinical room is avoided. As a result, “sedation” anesthesia employing nitrous oxide may now be practiced more readily in hospitals, surgical centers and doctor&#39;s offices in a safe and effective manner thereby leading to increased patient satisfaction and reduced medical costs. 
     Many variations and modifications to the foregoing will be readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. Therefore, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as defined in the annexed claims. 
     The components of the respiratory face mask and breathing circuit assembly of the invention can be made from inexpensive and durable plastic or metal materials. 
     As to the manner of usage and operation of the instant invention, the same is apparent from the above disclosure, and accordingly, no further discussion relative to the manner of usage and operation need be provided. 
     Finally, it will be appreciated that the purpose of the annexed Abstract is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. Accordingly, the Abstract is neither intended to define the invention or the application, which only is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.