Disposable Anesthesia-breathing Circuit Unit

Abstract

This application discloses an anesthesia gas delivery system to be coupled between an anesthesia machine and a patient so as to form part of a complete breathing circuit. This system includes conduits coupled to an intermediate connector which, in turn, is applied to the patient using a face mask forming a part of the system or an endotracheal tube. It further includes a breathing bag to be connected at the appropriate place in an anesthesia machine. In order that the system may be disposable after single patient use and to provide for patient safety, there is included a filter for removing harmful particles from gas circulating in the system. In addition, all elements in the system are arranged to be electrically conductive or antistatic to avoid the danger of explosion.

Parent Case Text

This application is a continuation-in-part of application 748,524 filed July 29, 1968, now abandoned.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to systems for supplying gases for respiration by living things. More specifically, it relates to apparatus for supplying anesthetics to human beings.

As used in this application, the breathing circuit includes all the elements of a gas delivery system (defined below) and certain elements of the anesthesia machine such as relief valves, gas inlet, vaporizer (if needed), soda-lime absorbers and the conduits interconnecting them. The term gas delivery system includes the face mask (or endotracheal tube) and the flexible tubing and connectors coupling these elements to an anesthesia machine. It also includes a breathing bag and in the particular context of this application a filter as will be developed subsequently.

It is important to keep in mind as one attempts to appreciate this invention and its background that a surgical procedure on a human being is always a critical matter and as it proceeds in an operating room, it is vital that many things seemingly small and isolated perform without creating "mechanical" problems. Therefore, reliability of apparatus and the avoidance of new problems while seeking to solve old ones are absolute essentials. In the context of this invention, this means that any attempt to change a long standing surgical practice by introducing a new approach in operating room procedures and apparatus will and should be evaluated in very large part on its ability to perform as well as or better than what is presently available. So where there is existing apparatus for which standards of performance and desired objectives have evolved over the years any degradation in these is not only undesirable but perhaps not even permissible. It is not overstating the matter to say that this is particularly true of systems supplying anesthetics.

In contemporary medical practice a number of clearly delineated standards or objectives have developed with respect to the nature and capabilities of apparatus for supplying anesthetics to patients undergoing surgical or other therapeutic procedures. These standards, in large part, are concerned with the effectiveness and safety of the apparatus.

Such standards include, among others, the need to supply the anesthetic to the patient in quantities which can be controlled and in such a manner that its effect can be assessed by the anesthesiologist. Thus, in an anesthesia-breathing circuit there is usually included a breathing bag which serves as a means by which the anesthesiologist senses the pressure exerted by the patient as he exhales. The bag also functions as a gas reservoir which may be squeezed by the anesthesiologist to provide pressure for manual ventilation of gas being inhaled by the patient, if necessary. A breathing bag, in order to serve these purposes well, must have certain qualities. Firstly, the bag should not be noticeably distensible. Were it to do so the anesthesiologist would have a difficult time controlling the gas pressure and volume. Secondly, it should have what might be termed as good "feel characteristics," it should be thin enough or feel thin enough for the anesthetist to sense the pressure being exerted on the patient's respiratory system when he is ventilating the patient. Another quality which should be present relates to the surface of the bag which should exhibit a slight tackiness so that it may be grabbed or squeezed without having one's hands slip off.

Another element in anesthesia circuit which is expected to have certain capabilities is the face mask held on the face of the patient and through which the gas is delivered. It is important that the mask have a minimum of dead air space. By this is meant that the space between the portions of the face encompassed by the mask and the interior mask surface be at a minimum. The reason for this is that it is desired to minimize the amount of the patient's exhaled breath which he rebreathes on the next inhalation. Minimum dead air space also allows the anesthesiologist to have the best possible control of gas mixtures available to the patient. In addition, it is important that a good seal be maintained between the surface of the patient's face and the mask in order to minimize gas leakage and again to insure that the patient receive the desired quantity of gas. Another desired quality is the even distribution of pressure about the patient's face in order to avoid pressure points. The objective in this instance is the desire to avoid traumatic situations such as skin irritation or other injury caused by excessive pressure at any point on the face. To the extent consistent with these objectives, the weight of the mask should be kept as low as possible to obtain greater patient comfort.

In addition to the elements that have been discussed, the anesthetic gas delivery system includes the tubes and connectors for supplying the gas to the patient and returning the patient's exhaled breath to the machine. The breathing bag discussed above is connected to that portion of the gas flow circuit included as a part of the machine but is considered herein as a part of the anesthesia gas delivery system.

Such a system, in addition to having the qualities discussed above, should be electrically conductive, to avoid sparking which could result from the buildup of electrical charges. Many anesthetic gases as well as other types of gases used in operating rooms are potentially explosive and could be set off by such sparking. The system should also prevent the transmission of particles such as bacteria from one patient to another. Insofar as prior art systems are concerned, the objective of removing bacteria has been met by cleaning and sterilizing.

There are in existence a number of gas delivery systems which come near meeting or do meet all these features. However, they do this be requiring the use of expensive materials and relatively expensive manufacturing procedures. Consequently, their cost is relatively high. As pointed out, in order to reuse them they must be cleaned and sterilized to minimize the possibility of cross infection from one patient to another. Sterilization procedures take time and require the use of personnel and equipment which adds to their overall cost. The increased safety which could be obtained with a single use unit makes such a system highly desirable if one could be produced cheaply enough to make its adoption economically feasible.

SUMMARY OF THE INVENTION

Therefore, it is an object of this invention to provide a single use anesthesia-breathing circuit which, while capable of meeting or exceeding the standard of performance expected in such units, will at the same time provide the capability of substantially reducing the possibility of cross contamination.

It is another object of the invention to provide an anesthesia-breathing circuit which is capable of protecting the operation room environment from infection caused by infectious particles which may be present in a patient's exhalation.

It is another object of this invention to provide an anesthesia-breathing circuit which is capable of protecting a patient on whom it is being used from cross infection as the result of a prior use of the anesthesia circuit on another patient.

These and other objects are achieved by providing an anesthesia-breathing circuit system which is fabricated out of materials and uses manufacturing techniques which tend to substantially reduce the cost of such units and render them disposable. The system is made electrically conductive to minimize the risk of explosion and includes means to remove harmful particles so as to substantially reduce the risk of cross infection from one patient to another or other harm to a patient's respiratory system.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention itself is defined in the claims which are appended hereto, but the foregoing and other objects, as well as understanding of various embodiments of the invention, will be understood by reference to the following description read in the light of the drawings in which:

FIG. 1 is a schematic view of an anesthetic circuit constructed in accordance with the invention;

FIG. 2 is a front view of a disposable face mask forming a part of the invention;

FIG. 3 is a cross section view along the line 3-3 of FIG. 2;

FIG. 4 is a planar view of a preferred form of a connector for use in the invention;

FIG. 5 is a front view of one element of the connector;

FIG. 6 is a cross-sectional view of another element of the connector;

FIG. 7 is a front view of a breathing bag forming a part of the invention;

FIG. 8 is a top view taken along the line 8-8 of FIG. 7;

FIG. 9 is a side view of a connecting bushing for use with the breathing bag;

FIG. 10 is a planar view of a filter for use in the invention;

FIG. 11 is an exploded view of the filter of FIG. 10;

FIG. 12 is a cross-sectional view of the filter taken along its longitudinal axis;

FIG. 13 is a cross-sectional view of the filter taken along its transverse axis;

FIG. 14 is an illustration of an alternative location of a filter for use in the invention; and

FIG. 15 is an illustration of still another alternative embodiment of the invention.

DETAILED DESCRIPTION

FIG. 1 of the drawing illustrates generally an anesthesia-breathing circuit wherein the invention may be used and further illustrates the invention in use and forming a part of a complete anesthetic delivery system. This figure schematically illustrates a face mask (or endotracheal tube) 2 to be attached to a patient. A coupling element as in this embodiment takes the form of a connector 3 having a tee element 4 for attaching the connector to the mask and including two tube elements 5 connecting to a pair of corrugated conduits 6 and 7. The conduit 6 connects with a breathing bag 8 through a check valve assembly 10 while conduit 7 connects with a filter 9 for removing infectious media, such as bacteria, from the system.

As the gas exhaled by the patient flows through the conduit 6 (shown by the arrows), it passes through the check valve assembly 10 which permits unidirectional flow to the breathing bag 8 and prevents back flow through the conduit 6 if the bag is squeezed. An anesthesia machine to which the disposable elements constituting the invention are to be connected includes the check valve and the elements in the flow circuit extending from the bag to the filter 9. A pressure relief valve 13 is constituted by a spring 14 which biases a valve head 15 onto seat 16 in a closed position. This valve permits pressure relief when the pressure in the conduit 11 exceeds the pressure on the head 15 exerted by the spring 14. Conduit 11 connects to an exhalation check valve assembly 17 which maintains unidirectional flow and prevents exhalation flow through the inhalation side of the circuit. A pressure gauge 18 may be provided in order to read back pressure before the conduit connects with an absorber apparatus 12.

The absorber apparatus 12 includes a bypass valve 19 comprising a rotatable element sealed against the walls of the canister of the valve and which permits flow through soda-lime maintained in the canister for absorption of the carbon dioxide in the exhalation. The soda-lime may be bypassed by rotating the closure element 90.degree..

As the gas flow exits the absorber apparatus 12, fresh gas (oxygen, nitrous oxide, etc.) may be added through an inlet 20. The flow thereafter may move through a vaporizer 21 either by bubbling or otherwise and then pass through the filter 9. It should be appreciated that the elements 10 through 21 constitute parts of the anesthesia machine and are shown in a schematic form for these are well-known in the art and do not form a part of the invention. Therefore, in the embodiment of the invention illustrated in FIG. 1, it is constituted by the face mask 2, the connector 3, the conduits 6 and 7, the breathing bag 8 and the filter 9.

A first element to be discussed is the face mask 2. This mask is shown in FIGS. 2 and 3 as having a cone or relatively thin face piece 22. The cone is preferably made of a conductive vinyl plastic using injection molding or vacuum forming techniques. It includes an edge portion 23 which has integrally formed therewith a first surface 24 which extends slightly outwardly in a direction on one side which may be termed the forward direction. The first surface 24 blends into a second surface 25 which is relatively flat. Extending outwardly in the forward direction of the face piece 22 is a nose accommodating portion 26. Formed in the face plate below the portion 26 is a gas supply tubing attachment 27 encompassing an opening 28 in the face plate.

A cushion 29 is formed in place onto the other side 30 of the face plate to form with the face plate a face mask which resiliently conforms to the wearer's face. The cushion 29 has a relatively wide base or bottom portion 31 secured to the surface 30 and a relatively narrow top portion 32 which provides a contoured surface to engage the surface of the patient's face.

By particular reference to FIG. 3 it may be seen that the face mask when applied to the face of a patient may be pressed gently against the face so that the contoured surface conforms to the contour of the face. In addition the cushion 29 being formed of a foamed plastic material compresses, it being noted that the amount of compression may be controlled by hand pressure or by a head strap (not shown) used to secure the mask to the patient's face and held on the mask by the studs 34. In addition, by providing a deformable wire 35 formed of any suitable material on the underside of the surface 24 and retained in part by the foamed cushion 29, the face plate may be bent to any desired shape to better accommodate the facial contours of a particular patient. When applied and secured in the manner indicated, the patient's nose and mouth will be positioned very close to the face plate 22. In these circumstances, some portion of the nose will be positioned within the nose-accommodating portion 26. Consequently, there will be a minimum of space between the inner surface of the mask and the patient's face. The minimizing of this space (dead air space) is a main consideration in the construction of a face mask in order to eliminate as much as possible the patient's exhalation which is rebreathed on a subsequent inhalation.

In addition to the foregoing, the deformable cushion 29 will function to maintain a good seal between the mask and the patient's face. Also it will act to evenly distribute the pressure of the mask over the surface of the face and thus minimize the possibility of skin trauma.

Cushion 29 may be made conductive by forming it of a conductive material or by coating it with a liquid containing carbon particles by a dip or spray process. Obviously, other conductive materials which may be applied to the surface of the foamed cushion 29 are suitable and may be used.

In the embodiment of the invention illustrated, the means for connecting the conduits 6 and 7 to the mask is shown in detail in FIGS. 4 through 6. Connector 3 is comprised of a tee element 4 and two connector elements 5. The connector elements 5 are mounted on the tee element 4 so that they may swivel thereon.

As shown in FIG. 5, the tee element 4 is a hollow member which comprises a tubular head portion 36 and a tubular leg portion 37. The leg portion 37 has an outside diameter 38 for secure insertion in the tubular attachment 27 of the mask 2. Its inside diameter 39 is dimensioned to be of a size so as to securely receive a commonly used endotracheal tube connector if such is desired to be used. The head portion 36 is provided with a pair of annular grooves 41 which are formed by tapered first and second ribs 41 and 42.

Each connector element 5, as shown in FIG. 6, comprises a tubular member 43 having a circumferential abutment 44 and a tapered end 45 facilitating the positioning of the corrugated conduits 6 and 7 on the tubular member 43. Each element 5 also includes an opening 46 at an angle to its longitudinal axis, the periphery of which is formed by an annular rounded projection 47. The diameter of the opening 46 is selected to be less than the diameter of the groove 40 in order that the element 5 may be positioned on the tee element 4 using a relatively light force and be maintained thereon when the surface 47 engages in the groove 40.

Since an interference fit is used to connect the elements 5 to element 4 and these elements are made of a plastic material, it is desirable during assembly process to soften the elements at the connecting points, preferably adjacent the surfaces 47, with heat in order to temporarily increase the elastic properties of the material. When heated with resulting increased elasticity, the surfaces 47 are forced over the tapered ribs 41 to be retained in the grooves 40. After cooling, the connection of the elements 4 and 5 will provide a swiveling substantially gastight connector with the elements 5 rotatable with respect to the element 4. Both of these elements may be injection molded of conductive plastic material. However, they could be made from a nonconductive material with some other means used to provide the desired electrical conductivity.

The disposable breathing bag 8 is shown in detail in 7 through 9 and comprises four side panels 48--51, two of which, 49 and 51, are gusseted. The panels 49, 50, and 51 are preferably made of antistatic vinyl plastic. These materials are selected so that the resultant dielectric characteristics of the bag may be used to heat seal the edges of the panels to form the desired enclosure. Thus, after the panels have been cut to shape, dielectric heating apparatus may be used to seal the edges.

Breathing bags formed in accordance with this aspect of the invention have been fabricated out of 0.010 inch thick vinyl in a particular apparatus embodying the invention. When so fabricated, they have been found to be thin enough to permit the anesthesiologist to feel the pressure being exerted on the patient's respiratory system. In addition, they have been found to have a good compliance characteristic. That is, they do not distend as gas is forced out of the bag when pressure is exerted on it. Also, the surface of the bag exhibits a degree of tackiness so that the possibility of hands slipping from the bag as it is gripped is considerably diminished.

The bag is formed to have a neck 52 having an outwardly flaring rim 53 to facilitate the reception of a bushing 54 therein. The neck 52 is formed of extensions of side panels 48 and 50. Bushing 54 is preferably made of a conductive plastic having an extension 55 of lesser outer diameter and provided with a tapered end 56. In order to assemble and secure the bushing 54 in the bag 8, an adhesive is applied to the extension 55 up to a shoulder 57. The bushing is then inserted in the neck 52 up to a shoulder 57. The bushing is then inserted in the neck 52 and the adhesive dried and/or cured so as to maintain the bushing in position. If desired, the bushing may be further secured and sealed in the bag by tape 58 wrapped tightly around the neck. Preferably, the tape may be made of vinyl plastic. Alternatively, ultrasonic or dielectric welding means may be used to further secure the bushing to the bag.

The conductive vinyl bushing makes intimate contact with the neck extension of the conductive panel 48 of the bag and thereby provides a conductive chain to the metal structure of the anesthesia machine. Thus, the bag by virtue of its structure and connection to the machine, as with the other elements of a disposable breathing circuit in accordance with the invention, substantially eliminates the buildup of electrical charges.

As noted above, it is important that cross infection between patients be eliminated with apparatus of the type disclosed. In this embodiment of the invention, it is proposed to accomplish this by providing the bacteria filter 9. FIGS. 10 through 13 illustrate a filter which may be used for this purpose. In FIG. 10, the construction of such a filter is generally shown. The filter comprises a housing formed of a conductive plastic material having a body 58 and a cap 59. These are both hollow members and enclose the filter member 60 shown in FIGS. 11 and 12. The body 58 has an inlet 61 and the end cap 59 has an outlet 62.

The filter 9 may be formed of a cellulose and glass fibrous material 60 bonded with epoxy resin. Its physical structure is constituted by an annulus of corrugated filter material secured to end plate 64. The filter is bonded by any suitable means such as by the use of an adhesive to the interior surface of the end cap 59. Its longitudinal extent is such that when so bonded and when the end cap is fitted over the wide end of the housing 58, the end plate 64 will be spaced a distance from the opening of the inlet 61. Likewise, its diameter is selected to be one which will provide a space between the filter and the wall of the housing 58. By virtue of this arrangement gas passing through the system preferably enters through the inlet 61 and passes through the filter material and out the outlet 62.

A filter of the type described has been found effective to achieve substantially 100 percent elimination of the bacteria which may be carried by the gas as it passes therethrough. Examples of bacterial species which have a morphology of the coccus type are staphylococus aureus and streptococcus. These bacteria have average diameters of 0.8 and 0.5 to 1.0 microns, respectively. Bacterial species having a morphology of the rod type which have been eliminated using a filter in accordance with the invention include escherichia colli, pseudomonos aeruginosa, salmonella and mycobacterium tuberculosis which have dimensions ranging from 0.2 to 0.8 by 1 to 4 microns.

While in FIG. 1 the filter 9 is shown as being provided between the end of the conduit 7 and the vaporizer 21, it need not be mounted solely in that location. In that location it in effect serves to protect the patient from bacteria which may have been transmitted into the anesthesia machine as the result of previous patient usage. On the other hand, it may be desirable to protect the anesthesia machine and the entire operating room environment from a highly infectious patient. If this be so, the filter may be mounted between the connector 3 and the face mask 2. This embodiment is shown in FIG. 14. FIG. 15 illustrates another embodiment of the invention where the filter 9 is connected between the end of the conduit 6 and the anesthesia machine to protect it from contamination by a highly infectious patient.

The invention itself in its various aspects and embodiments has been described and shown in the accompanying drawings, all of which are intended as illustrative, and the invention itself is limited only as set forth in the claims.

Claims

I claim:

1. In an anesthesia gas delivery system for providing an anesthetic gas to a patient including a face mask, first and second conduit means, connector means to connect said first and second conduit means to said face mask, said first conduit means receiving fluid exhaled from the patient, first check valve means connected to said first conduit means to prevent a reverse flow of the exhaled fluid in said first conduit means, a breathing bag associated with said first check valve mean, relief valve means in fluid communication with said first check valve means, exhalation check valve means in fluid communication with said relief valve means, absorber means receiving the exhaled fluid, fluid inlet means for adding fluid to the exhaled fluid, anesthetic vaporizer means receiving the exhaled fluid and adapted to provide fluid for inhalation, said anesthetic vaporizer communicating with said second conduit means, and a filter means removing extraneous particles from fluid circulating in the system, the improvement wherein the face mask, connector means, first and second conduit means and the filter means are disposable and readily detachable from said first check valve means and said vaporizer means after use.

2. An anesthesia gas delivery system as defined in claim 1 wherein said face mask has a first element comprising a relatively thin molded plastic face piece having: an edge surface; a first integral surface extending outwardly from said edge surface on one side of and toward the center of said face piece; a second integral surface extending from said one side and toward the center of said face piece from said first surface; a nose-accommodating portion extending from said second surface on said one side and having an opening formed thereinbelow said nose-accommodating portion; and a second element comprising a foamed plastic compressible cushion secured to and extending from the other side of said face piece to engage the surface of the face surrounding the nose and mouth.

3. An anesthesia gas delivery system as defined in claim 2 wherein said cushion is coated with a conductive material.

4. An anesthesia gas delivery system as defined in claim 2 wherein said cushion has a relatively thick bottom secured to said other side of said face piece and tapers toward a thinner face-engaging surface.

5. An anesthesia gas delivery system as defined in claim 2 wherein said face mask is provided with integrally formed projections extending from said one side thereof to receive straps for holding said face mask to the face.

6. An anesthesia gas delivery system as defined in claim 1 wherein said first conduit means has one end connection for coupling to the first check valve means and a flexible tube extending from said one end connection; said second conduit means has one end connection for coupling to the anesthetic vaporizer means and a flexible tube extending from its said one end connection; and said connector means comprises a coupler having first and second openings connected to the free ends of said flexible tubes of said first and second conduit means, respectively, and a third opening connected to said face mask.

7. An anesthesia gas delivery system as defined in claim 6 wherein said coupler comprises: a cross tube having end openings and an opening intermediate its ends; an integral tube extending from said tube having access to said intermediate opening, said intermediate tube connected to said face mask; and a connector tube swiveled on each end of said cross tube around said end openings providing the connections to said free ends of said flexible tubes of said first and second conduit means.

8. An anesthesia gas delivery system as defined in claim 7 wherein said filter means is connected to said flexible tube of said first conduit means to constitute its said one end connection.

9. An anesthesia gas delivery system as defined in claim 7 wherein said filter means is provided on said coupler.

10. An anesthesia gas delivery system as defined in claim 7 wherein said filter means is connected to said flexible tube of said second conduit means.

11. An anesthesia gas delivery circuit as defined in claim 1 wherein said breathing bag is readily detachable from association with said first check valve means and is disposable.

12. An anesthesia gas delivery circuit as defined in claim 11 wherein said breathing bag comprises a plurality of panels joined along their edges and made of antistatic material and at least one panel including a conductive portion.

13. An anesthesia gas delivery circuit as defined in claim 11 wherein said breathing bag comprises a plurality of panels joined along their edges made of an antistatic material.

14. An anesthesia gas delivery circuit as defined in claim 11 wherein said breathing bag comprising four panels joined along their edges.

15. An anesthesia gas delivery circuit as defined in claim 12 wherein said breathing bag includes a neck and a bushing joined to said neck.

16. In an anesthesia gas delivery system for providing an anesthetic gas to a patient including a gas communication means adapted to be placed in contact with a patient, connector means in gas flow relation to said communication means and having a pair of connector elements, first and second conduits each having one end in gas flow relation to a respective one of said pair of connector elements, said first conduit receiving fluid exhaled from the patient, first check valve means connected to said first conduit to prevent a reverse flow of exhaled fluid in said first conduit, a breathing bag associated with said first check valve means, relief valve means in gas flow relation to said first check valve means, exhalation check valve means in gas flow relation to said relief valve means, absorber means in gas flow relation to said relief valve means, fluid inlet means for adding an additional fluid to the gas flow, anesthetic vaporizer means in gas flow relation to said absorber means, said anesthetic vaporizer being connected to said second conduit to provide fluid for inhalation to the patient, and a filter means removing extraneous particles from the gas flow through the system, the improvement wherein the gas communication means, connector means, first and second conduits and the filter means are disposable and readily detachable from said first check valve means and said anesthetic vaporizer means.

17. The system set forth in claim 16 wherein said communication means is a face mask and said mask comprises a conductive plastic face piece and a foam plastic cushion adapted to resiliently conform to the facial contour of the patient and having a gas supply tube attachment means and wherein the cushion has a conductive coating.

18. The system set forth in claim 16 wherein said connector means has a Y configuration and comprises a hollow tee element having a leg and a head with the leg of said tee element connecting to said communication means, and said connector elements are rotatably fitted on opposite ends of the head and wherein said connector means is made of electrically conductive plastic material.

19. The system set forth in claim 16 wherein said first and second conduits are corrugated tubes made of electrically conductive material.