Reservoir Bag For Anesthesiology

Abstract

A thin walled bag formed of elastomeric or plastic material having good tactile sensitivity has a neck with an opening formed therethrough, said neck being stretched over a molded adaptor. The adaptor has projections extending into the bag to prevent obstruction of the neck opening when the bag is pulled to one side.

Parent Case Text

This application is a continuation of application Ser. No. 185,077, filed Sept. 30, 1971, now abandoned.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to anesthesiology systems and more particularly to a disposable breathing or reservoir bag for an anesthesiology system.

2. Description of the Prior Art

Heretofore, anesthesiology systems were equipped with reusable reservoir bags which among other things served as a means by which the anesthesiologist sensed the pressure changes produced by the pateint during ventilation, thus sensing patient response to, and stage of, anesthesia. There were two major requirements for a practical reservoir bag. Firstly, the bag had to be formed of electrically conductive material because some of the gases used during anesthesia were of an explosive nature. Secondly, the bag had to have good tactile sensitivity to allow the anesthesiologist to sense the pressure changes transmitted by the patient's respiratory efforts.

Because of these requirements, the reservoir bags were relatively expensive to produce and therefore not considered disposable. Consequently, the bags had to be cleaned and sterilized between uses to minimize the possibility of cross contamination from one patient to another. The sterilization procedures consumed considerable time and required the use of equipment and personnel which added greatly to overall operating cost.

Generally, the reservoir bags were flushed with antiseptic between uses in an attempt to destroy harmful microorganisms, however, this procedure proved to be only partially effective, and as a result, many patients were subjected to possible cross infection with microorganisms from other patients.

In an attempt to overcome this problem, one prior art device utilized disposable liners within the bag that could be discarded after each use to prevent contamination of the interior of the bag. While this device greatly reduced the possible occurrence of cross contamination, considerable time was required to insert and remove the liners from the bags and the device proved to be impractical.

There were attempts to provide a dip formed thin walled reservoir bag; however, it was discovered that the neck portion of the thin walled bag was weak and subject to tearing when the bag was being connected to an anesthestic system. As a result, it was required that the neck portion be dipped several times to form a thicker wall; however, this greatly increased the cost of manufacture and rendered the bag expensive and non-disposable.

In another attempt to provide a disposable reservoir bag, plastic sheets were heat sealed together to form a bag. This bag was not expandable and therefore no physical indication was provided when an overpressure condition developed. Such a condition is detrimental to a patient. The seams of this bag were subject to rupture and leakage, and thus, the bag did not provide an acceptable substitute for the previously used non-disposable reservoir bags.

Another difficulty encountered with the bags of the prior art was in the connection of the bags to the anesthetic system. There was a tendency during use for the bag to be pushed or pulled to one side of the anesthetic system, and as a result, the neck of the bag would become obstructed isolating the bag from the remainder of the anesthetic system. There was also a tendency for the bags having an adaptor to accidentally slip from the adaptor resulting in escape of anesthetic gases to the atmosphere.

SUMMARY OF THE INVENTION

The present invention contemplates a disposable breathing or reservoir bag for use with an anesthetic system. The bag is formed of an elastomeric material such as latex rubber or a plastic and is formed by dipping a form into a latex solution and thereafter curing the latex to make the bag which is then removed from the form. This procedure provides a bag having a thin wall of uniform thickness and good tactile sensitivity to assist the anesthesiologist in determining the patient's lung compliance and thus sensing the patient's response to, and stage of, anesthesia. Since the bag is formed of an elastomeric material, the bag expands under overpressure conditions thus relieving some of the pressure that would be transmitted to the patient's lungs if a non-expandable bag was used. This expansion also gives a physical indication that the system is becoming overpressurized.

The bag is formed with a neck portion having an opening therethrough which is stretched over a molded adaptor. The adaptor has a generally cylindrical exterior surface with an outwardly extending flange formed around the periphery at the midpoint thereof. The neck of the bag is extended over and beyond the flange where it is secured to the adaptor by the use of a heat shrinkable band. The flange helps to secure the bag to the adaptor and prevents inadvertent slippage of the bag from the adaptor. The adaptor is formed so that it can be easily connected to and detached from standard anesthetic systems without the need for other special connectors.

A unique characteristic of the adaptor is that it has projections that extend into the bag to prevent obstruction of the anesthetic system when the bag is either pulled or pushed to one side of the anesthetic system. In the prior art devices, if the bag were inadvertently pushed to one side, the neck would obstruct causing the bag to be isolated from the anesthetic system.

A most important characteristic of the reservoir bag, contemplated by the present invention, is its low cost which is a result of the method used in manufacture of the thin walled bag. Because of the use of a molded adaptor, the neck of the bag may be of the same thickness as the remainder of the bag because the adaptor provides added strength for the neck portion. Since the bag may be of uniform thickness, it may be formed by a single dipping operation thereby eliminating the need for additional dippings. Thus, the manufacturing operation is simplified and costs are greatly reduced.

The reduced cost renders the bag disposable and also eliminates the cost of sterilizing the bag between uses. In addition to the cost savings resulting from this type of bag, the most important advantage of this bag is that all possibility of cross contamination resulting from the use of the same bag on more than one patient is eliminated. This advantage alone makes the present invention a substantial improvement over the bags of the prior art.

The material from which the reservoir bag is made may be conductive or non-conductive elastomer or plastic material. The conductive material is required when the anesthetic agent used is an explosive gas; however, the trend in some hospitals today is towards the use of non-explosive anesthetic agents and in such cases a non-conductive bag may be used. Non-conductive bags have many advantages over the conductive type in that they may be produced at a lower cost and they may also be made of transparent, translucent or colored material rather than the black conductive type of material presently required for conductive bags.

The main objective of the present invention is to provide a reservoir bag that is disposable so that all possibility of cross contamination caused by the reuse of reservoir bags will be eliminated.

Another objective of the present invention is to provide a reservoir bag that is less expensive than the bags heretofore provided.

Another objective of the present invention is to provide a disposable reservoir bag whereby the cost of sterilization between uses is eliminated.

Another objective of the present invention is to provide a reservoir bag that expands and increases in volume under overpressure conditions.

Another objective of the present invention is to provide a reservoir bag that has good tactile sensitivity.

Another objective of the present invention is to provide a reservoir bag having an adaptor that prevents obstruction of the bag opening when the bag is pushed to one side.

Another objective of the present invention is to provide a reservoir bag that includes an adaptor to provide added strength in the neck portion of the bag and to facilitate connection and disconnection from an anesthetic system.

Another objective of the present invention is to provide a superior connection between a reservoir bag and an adaptor.

The foregoing objectives and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawings wherein twoo embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawings are for illustrative purposes only and are not to be considered as defining the limits of the invention.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an assembly drawing of a bag constructed in accordance with the present invention.

FIG. 2 is a drawing showing the assembled bag of FIG. 1.

FIG. 3 is a partial sectional view taken along line 3--3 of FIG. 2.

FIG. 4 is an end view of the adaptor taken along line 4--4 of FIG. 1.

FIG. 5 is a sectional view taken along line 5--5 of FIG. 1.

FIG. 6 is a sectional view corresponding to that of FIG. 5 of another embodiment of the present invention.

DESCRIPTION OF THE INVENTION

Referring to FIG. 1, there is shown an assembly drawing of the reservoir bag of the present invention. The reservoir bag comprises a thin walled bag 11, an adaptor 13 and a band 15. The bag has a neck portion 17 having an opening 19 formed therethrough. The bag is thin walled having a thickness in the range of 0.010-0.025 inches and is formed by a dipping process. A form having an outer surface configuration similar to the desired bag configuration is dipped into a latex solution and then removed. The latex solution adheres to the form after the form is retracted from the solution and the latex is then cured forming a thin walled bag which is then removed from the form.

Referring to FIG. 5, it may be seen that the bag has an H-shaped cross section. There are many possible cross sections that may be used in the practice of the present invention such as the X-shaped cross section shown in FIG. 6. The H-shaped cross section is preferred because it facilitates the removal of the bag from the form. The neck portion 17 of the H-shaped bag need not be stretched as much to remove the bag from the form as would be required to remove the bag from an X-shaped form as shown in FIG. 6. This is particularly significant when a conductive bag is being manufactured because in such instances carbon particles are distributed in the latex solution to render the solution conductive and undue stretching of the cured latex may have an adverse affect on the conductivity of the final product. Another advantage of the H-shaped cross section is that it facilitates packaging of the bag because the bag has a natural flat configuration.

A preferred bag capacity is 3 to 5 liters, and the bag must be of sufficient strength to withstand a gauge pressure of at least 6 cm of mercury without leakage or rupture.

When the bag is to be used for explosive anesthetics, carbon particles are intermixed with the latex to form a conductive material from which the bag is made. The maximum electrical resistance of the bag must be 1 megohm or less. The conductivity, provided by 1 megohm, is required so that static charges collected on the surface of the bag may be conducted to ground to avoid discharge by sparking and the possibility of igniting the explosive anesthetic mixture.

If a non-conductive bag is desired for use with a non-explosive anesthetic elastomeric or plastic material may be used without carbon to form the bag. Since carbon is not required, the bag may be made clear or any color.

While any elastomeric flexible material of low gas permeability may be used to form the bag, latex rubber has good tactile sensitivity and allows the anesthesiologist to sense the pressure changes transmitted by the patient during ventilation.

The latex rubber is also elastomeric and allows the bag to expand when an overpressure condition exists. This characteristic has two advantages. Firstly, the expansion of the bag tends to reduce the pressure to which the patient is exposed. Secondly, it provides a physical warning to the anesthesiologist or other attendant that the patient is being exposed to an overpressure condition.

Referring again to FIG. 1, it may be seen that bag 11 has a tip 21 formed at an end opposite the neck portion 17. The tip is formed so that the bag may be connected in series in a different type of anesthetic system. When a series connection is desired, the tip is cut off and an adaptor inserted into that end of the bag so that the bag has an inlet at one end and an outlet at the other end.

Adaptor 13 is molded from a conductive hard rubber or plastic material. The adaptor has a cylindrical shape having an outside diameter of approximately 1 5/32 inches and has a tapered opening formed therethrough. The widest inside diameter of the opening is approximately 0.863 inch and the taper is approximately 0.025 inch diameter per 1 inch of length. An outwardly extending flange 23 is formed about the periphery of the adaptor and has a circular channel 25 formed therein. Three equally spaced projections are formed on one end of the adaptor, the function of which will be explained subsequently.

During assembly, the neck portion 17 of bag 11 is stretched over adaptor 13 and flange 23 so that it extends to within approximately one-fourth inch of end 29 of adaptor 13. The neck portion is then released and because of its elastomeric characteristic, it conforms to the outer shape of the adaptor.

Band 15 is formed of a heat shrinkable material such as clear polyvinyl chloride having a thickness of approximately 0.0030 inches, a diameter of approximately 50 mm and a width of about five-eighths inch. Band 15 is placed over adaptor 13 so that it partially overlaps the adaptor and partially overlaps neck 17 of bag 11. The band is then heated causing it to shrink and form a secure connection between the neck 17 and adaptor 13. The band need not be conductive because an electrical connection is made between the bag and the adaptor and the adaptor itself is electrically connected to the anesthetic system.

An alternate method of connecting neck 17 to adaptor 13 would be to use an O-ring driven into channel 25 after neck 17 is placed over the adaptor. The O-ring would then function to lock the neck in place over the adaptor and prevent its inadvertent slipping from the adaptor. Another method of connecting neck 17 to adaptor 13 would be to use a suitable bonding agent.

As can be seen most clearly in FIG. 3, the projections 27 of adaptor 13 project through neck portion 17 and into bag 11. These projections prevent obstruction of the neck and closure of its opening when the bag is accidentally pushed or pulled to one side.

Thus, the present invention provides an inexpensive, disposable reservoir bag for an anesthetic system. The bag has an adaptor that may be easily attached to and detached from the standard couplers used on anesthetic systems. The bag is formedof an elastomeric material and may be inexpensively manufactured from either a conductive or a non-conductive material. The bag expands under overpressure conditions which would otherwise be exerted directly into the patient's lungs, and also provides a visible indication that such a condition exists. The elastomeric material has a good tactile sensitivity so that the anesthesiologist may sense changes in the patient's lung compliance. A uniquely configured adaptor prevents inadvertent obstruction of the neck portion of the bag and also provides added strength to the neck so that the bag may be formed with a uniform thickness thereby reducing the manufacturing costs of the bag. The reduced cost renders the bag disposable and eliminates the costly sterilization procedure required of other reusable bags. The disposable characteristic of the bag taught by the present invention makes possible the elimination of any possibility of cross contamination of diseases between patients caused by the bag. Thus, the present invention provides a bag for an anesthesiology system that is less expensive and has many advantages over the bags heretofore provided.

Claims

We claim:

1. A low cost disposable two-piece reservoir bag, comprising:

an integral single-piece thin walled, substantially uniform thickness, a leak-proof bag of a flexible elastomeric rubber material, the bag elasticity and thinness cooperating in rendering the bag expandable under over-pressure conditions thereby avoiding exposure to the patient of excessive pressures, the bag being of low gas permeability and having a neck with an opening formed therein in communication with the interior of the bag, the bag having good tactile sensitivity and being conductive throughout all surfaces thereof;

conductive adapter means fixedly positioned within the neck and including a portion extending from said bag, the adapter having an annular radial projection extending therefrom intermediate the ends thereof, and the rubber neck being elastically stretched into engagement with the adapter over the projection to thereby provide a tight sealed interengagement between adapter and bag and to provide a continuous conductive path from end to end of the two-piece bag; and

projections formed on the adapter and extending into the interior of the bag for preventing obstruction of the opening when the bag is displaced to one side.

2. A disposable reservoir bag as described in claim 1, additionally comprising retaining means for retaining the neck portion of the bag around the adaptor means.