Abstract:
A unit in the form of a bubble pack for creating an anaerobic gaseous atmosphere in a bag and for indicating the presence of the anaerobic atmosphere in the bag. One bubble of the pack houses an acid-containing ampoule and also houses tablets which generate hydrogen and carbon dioxide when activated by squeezing the bubble to crush the ampoule and release the acid. Another bubble communicates with the first bubble by way of a tunnel-like bubble and serves as an expansion chamber for the gas and the released acid. Gas flows from the expansion bubble into the bag and enters still another bubble which houses an ampoule containing a redox color indicating liquid. When the latter ampoule is crushed, the liquid moistens an absorbent pad which changes colors as the atmosphere of the bag changes from aerobic to anaerobic.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to units for generating a predetermined gaseous atmosphere in a closed container and/or for indicating the presence or absence of the predetermined atmosphere in the container. More particularly, the invention relates to generating and/or indicating units for use by the medical profession in collecting, transporting and storing bacterial cultures of the type which remain viable only when in the presence of a particular gaseous environment or atmosphere. For example, bacteria of the anaerobic type require an oxygen-deficient or oxygen-free atmosphere and should be transported and stored in an environment having little or no oxygen. 
     Units used for somewhat the same general purposes as the units of the present invention are disclosed in Brewer U.S. Pat. Nos. 3,246,959 and 4,287,306; Spinner et al U.S. Pat. No. 4,013,422 and 4,023,934; Rosiere U.S. Pat. No. 4,012,203 and Johnson U.S. Pat. No. 4,377,554. The Spinner et al &#39;422 patent discloses a gas generating unit for creating an anaerobic atmosphere in a flexible bag while the Spinner et al &#39;934 patent discloses an indicator unit for visually signaling whether the anaerobic atmosphere is present or absent in the bag. In each unit, a sealed ampoule containing a liquid is disposed in a tube adapted to be inserted in the bag. When the ampoule of the gas generating unit is broken by squeezing the bag and the tube, the liquid in the ampoule is released and activates a gas generating material to create a flow of gas out of the tube and into the bag. When the ampoule of the indicator unit is broken, the released liquid soaks an absorbent material which assumes different colors depending upon whether the gas flowing into the indicator tube from the bag is aerobic or anaerobic. In this way, medical personnel can both create an anaerobic atmosphere in the bag and can visually determine whether or not the integrity of such atmosphere has been maintained over the required period of time. 
     SUMMARY OF THE INVENTION 
     The general aim of the present invention is to provide new and improved gas generating and/or indicating units which are simpler and less expensive to manufacture and assemble than prior units, which may operate effectively with the bag in a horizontal position as well as in an upright position and which are safer to use both from the standpoint of eliminating possible injury resulting during breakage of the ampoules and, in the case of the generating unit, eliminating possible injury resulting from a rapid build up of gas pressure. 
     A more detailed object of the invention is to achieve the foregoing by providing units whose ampoules and other components are uniquely arranged within the bubbles of bubble packs adapted to be inserted into flexible bags or the like, each bubble pack preferably having bubbles for receiving both the components of the generating unit and the components of the indicator unit so that both units are combined in a single package. 
     A further object is to provide a gas generating unit in which a liquid-containing ampoule is located in one bubble of a bubble pack and in which an adjacent bubble defines an expansion chamber into which the released liquid and gas may flow to avoid a rapid build up of pressure and to confine the liquid and the residue of the gas generating reaction within the bubbles. 
     The invention also resides in the provision of novel shields for preventing shards of the broken ampoules from penetrating the bubbles, the shield of each unit uniquely serving another function in addition to its protective function. Thus, the protective shield of the gas generating unit holds the ampoule in close proximity to solid gas generating material and restricts the flow of residue when the solid material reacts with the liquid released from the ampoule. The protective shield of the indicator unit is absorbent and coacts with the liquid of the ampoule to serve as a color indicator for signaling the condition of the atmosphere in the container. 
     These and other objects and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top plan view of a typical bag-type culture container equipped with a new and improved gas generator/indicator unit incorporating the unique features of the present invention. 
     FIG. 2 is a perspective view of the generator/indicator unit of the invention. 
     FIGS. 3 and 4 are enlarged fragmentary cross-sections taken substantially along the lines 3--3 and 4--4, respectively, of FIG. 2 show the ampoules prior to the ampoules being broken. 
     FIG. 5 is an enlarged fragmentary cross-section taken substantially along the line 5--5 of FIG. 3 and shows the ampoules being broken. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     For purposes of illustration, the invention is shown in the drawings in connection with a system for collecting, transporting and storing bacterial cultures. The overall system is generally similar in principle to some of the concepts disclosed in the aforementioned Spinner et al patents and also is generally similar to a system which has been sold in the past by the assignee of the present invention under the trademark &#34;BIO-BAG&#34;. While features of the invention are applicable with various systems, the invention will be explained specifically with a system of the &#34;BIO-BAG&#34; type. In addition, the invention will be explained specifically in connection with a system for maintaining the cultures in a substantially oxygen-free or anaerobic environment. 
     Basically, the present system includes a container in the form of a flexible pouch or bag 10 which defines an environmental chamber. The bag may be made from a transparent polymeric material of low gas permeability such as a laminate identified as No. CL 5040 (Clear Lam Products). The bag is of an elongated rectangular shape and includes upper and lower side panels 11 and 12 (FIGS. 3 and 5). Heat seals 13 (FIGS. 1 and 5) along the side margins of the panels coact with a heat seal 14 at the &#34;bottom&#34; end margins of the panels to seal the panels together along such margins. After the bag has been filled with components to be described subsequently, the &#34;top&#34; end margins of the bag may be sealed as indicated at 15 (FIGS. 1 and 4) with a conventional heat sealing unit (not shown) to establish an air-tight condition in the bag. 
     Specimens which are to be transported in the bag 10 and tested in a laboratory may be collected on one or more plates or dishes 17 (FIGS. 1 and 3) treated with a suitable growth media. In this particular instance, the bag is sufficiently large to hold a row of three standard 100 mm. petri dishes although the bag may be used with two dishes or only a single dish. 
     In addition to the dishes 17, the bag 10 holds two vented cups 18 and 19 (FIG. 1) each containing a catalyst which herein is in the form of palladium pellets (not visible) disposed within the cups. In the presence of palladium, hydrogren reacts with oxygen to form water and to reduce the surrounding atmosphere. 
     In use of the system as described thus far, the catalyst cup 18 is placed in the &#34;bottom&#34; portion of the initially open bag adjacent one corner thereof. The dishes 17 with inoculated media then are placed in the bag in tandem and right-side-up. Next, the catalyst cup 19 is placed in the &#34;top&#34; portion of the bag near the corner thereof diametrically opposite the cup 18. A unit 20 then is placed in the &#34;top&#34; portion of the bag, after which the heat seal 15 is formed to close the bag air-tight. 
     In accordance with the present invention, the unit 20 is a bubble pack and preferably is both a gas generating unit for creating a predetermined gaseous atmosphere in the bag 10 and an indicator unit for signaling the presence or absence of a predetermined atmosphere in the bag. As will become more apparent subsequently, the formation of the gas generator and the indicator as a single unit and as a bubble pack simplifies the manufacture and assembly of the components of the unit, enables the bag to be advantageously transported and stored in a horizontal position, and safeguards against the risk of personal injury when the gas is initially generated. 
     More specifically, the bubble pack unit 20 is of an elongated rectangular shape and includes a flat lower panel 21 (FIGS. 3 to 5) made of resiliently flexible and heat sealable material such as polypropylene having a thickness of about 0.0115&#34;. Heat-sealed to the flat upper side of the lower panel 21 around the four peripheral margins thereof as indicated at 22 in FIG. 2 is an upper panel 23 whose upper side is formed with a plurality of raised blisters or bubbles to be described subsequently. A suitable material for use as the upper panel is polypropylene having a thickness of about 0.025&#34;. 
     In carrying out the invention, the bubble pack 20 is formed with one bubble 25 defining a compartment 26 (FIG. 3) for material for generating a gas. In addition, the pack 20 is formed with another bubble 27 defining an expansion compartment or chamber for preventing the gas pressure from building up too rapidly in the unit and for receiving the reaction products resulting from generation of the gas. 
     As shown in FIG. 2, the bubble 25 is somewhat T-shaped and includes an elongated cross-bar portion extending in the direction of elongation of the pack 20. The stem portion of the T is shorter than the cross portion, is centered relative thereto and extends transversely from one side of the cross-portion. The expansion bubble 27 is spaced transversely from the other side of the cross portion of the bubble 25 and is the same length as the cross portion. A tunnel-shaped connecting bubble 30 (FIGS. 2 and 3) extends transversely between the bubbles 25 and 27 about midway along the length of the bubble 27 and defines a passage establishing communication between the compartment 26 and the expansion chamber 28. The bubbles are formed in the upper panel 23 in a conventional manner. 
     Disposed in and extending longitudinally of the cross portion of the bubble 25 is an elongated sealed ampoule 31 (FIGS. 3 and 5) made of glass or other frangible material, the ampoule substantially filling the cross portion of the bubble. The ampoule contains a quantity of liquid 32 for activating gas generating material 33 (FIG. 3). Herein, the ampoule contains 1.0 ml. of 2.7 N hydrochloric acid. 
     In the present instance, the gas generating material 33 takes the form of two tablets disposed in end-to-end relation in the stem portion of the bubble 25 and substantially filling the stem portion. Each tablet 33 is a mixture of potassium boro-hydride and sodium bicarbonate. When the acid 32 in the ampoule 31 is released, the acid reacts with the tablets 33 to produce a mixture of gases including hydrogren and carbon dioxide. 
     To generate the gases, the upper and lower sides of the bubble 25 are squeezed through the bag 10 between the thumb and the forefinger as shown in FIG. 5. Such squeezing breaks the ampoule 31 to release the acid 32 into the compartment 26 and to allow the acid to contact and react with the tablets 33. The resulting gases flow through the tunnel 30 to the expansion chamber 28 and then escape from the expansion chamber and into the bag 10 by way of two small openings 35 (FIG. 2) formed in opposite end portions of the upper side of the expansion bubble 27. The palladium catalyst in the cups 18 and 19 causes the generated hydrogen to react with the oxygen in the bag to form water. Thus, oxygen in the bag is removed and, in addition, the atmosphere in the bag is enriched with the generated carbon dioxide which causes the bag to inflate. 
     The chamber 28 defined by the expansion bubble 27 serves important purposes. First, it allows the gas in the chamber 26 to expand and to escape slowly into the bag 10 through the openings 35. Thus, the expansion chamber 28 prevents a sudden bluild up of gas pressure and avoids possible bursting of the bubble 25. As a result of the expansion bubble 27, the bubble 25 may correspond closely in size and shape to the ampoule 31 and the tablets 33 to prevent those components from shifting in the bubble 25 and yet there is no danger of the gas bursting the bubble 25. In addition, the expansion chamber serves as an overflow chamber for the released acid 32, the residue of the tablets 33 and any foam resulting from the reaction of the acid with the tablets. 
     As shown in FIG. 1, the bubble pack 20 is placed in the bag 10 in a position extending transversely of the bag and is located with the ampoule 31 closer to the sealed &#34;top&#34; end of the bag than the tablets 33. When the ampoule 31 is crushed, it is desirable to elevate the &#34;top&#34; end of the bag about one inch to promote the flow of acid 32 into contact with the tablets 33. 
     Advantageously, the tablets 33 and the center portion of the ampoule 31 are encircled by a sleeve 37 as shown in FIG. 3, the sleeve having a generally oval cross-sectional shape. The sleeve is made of glycol-modified polyethylene terephthalate with a thickness of about 0.009&#34; and prevents glass shards from the broken ampoule 31 from penetrating the lower panel 12 and/or the bubble 25 and causing personal injury when the ampoule is crushed (see FIG. 5). Moreover, the sleeve binds the tablets to the ampoule to keep the tablets in close proximity to the ampoule and the acid 32 which is released therefrom. The sleeve also tends to establish a dam between the compartment 26 and the tunnel 30 to hold the tablet residue in the compartment 26. 
     Further in keeping with the invention, the bubble pack 20 includes an indicator for signaling whether or not oxygen has been removed from the bag 10 by the generated gases. For this purpose, the upper side of the pack is formed with a bubble 40 having an elongated upper bubble portion 41 defining a compartment 42 (FIG. 5) and a lower bubble portion 43 (FIGS. 2 and 4) defining a compartment 44 which communicates with the compartment 42. The upper bubble portion 41 is elongated in the same direction as the bubbles 25 and 27 and is positioned transversely about midway between those bubbles. The lower bubble portion 43 is rectangular, projects transversely from the upper bubble portion and underlies the upper bubble portion in transversely centered relation therewith. As shown in FIG. 2, the bubble 40 is located at the opposite end portion of the pack 20 from the bubbles 25 and 27 and is sealed therefrom by heat sealing the upper panel 22 to the lower panel 21 along a transversely extending strip 45 (see FIGS. 1 and 5). 
     Disposed in the upper portion 41 of the bubble 40 is an elongated sealed glass ampoule 47 (FIGS. 4 and 5) containing a liquid 48, the liquid herein being a redox color indicating liquid such as 0.5 ml. of one percent resazurin. Underlying the ampoule 47 and disposed in the rectangular lower bubble portion 43 is a rectangular pad 50 of absorbent material such as white non-woven polyester. An additional pad 51 of white polyester encircles the upper portion of the ampoule 47 and extends along the major portion of the length of the ampoule 47. 
     Openings 53 (FIG. 2) in the bubble 40 permit the atmosphere of the bag 10 to enter the bubble. In the present instance, there are four openings 53 formed through the upper side of the rectangular lower portion 43 of the bubble 40 near the corners of the lower portion. Thus, the pads 50 and 51 are exposed to whatever atmosphere is present in the bag 10. 
     Shortly before the ampoule 31 is crushed to generate the gas, the ampoule 47 is crushed by squeezing the top portion 41 of the bubble 40 between the thumb and the forefinger as shown in FIG. 5. The color indicating liquid 48 thus is released from the ampoule and moistens the pads 50 and 51, the pads preventing glass shards from penetrating the bubble 40 and the lower panel 21. 
     When the ampoule 47 is first crushed, oxygen is present in the bag 10 and reacts with the color indicating liquid 48 soaked into the pads 50 and 51 to cause the pads to turn bluish-pink in color. After the ampoule 31 has been crushed and the gas starts to generate, the removal of oxygen from the bag causes the pads to gradually fade back to their original white color. Accordingly, the medical technican can visually observe the color of the pads and determine whether an anaerobic atmosphere has in fact been created in the bag. If the anaerobic condition is lost by virtue of the bag being punctured or poorly sealed, the pads will return to their bluish-pink color to warn the technician that oxygen is present and that a new culture perhaps should be obtained. 
     From the foregoing, it will be apparent that the present invention brings to the art a new and improved gas generator/indicator unit 20 whose components are housed within a single bubble pack. Following molding of the upper panel 23 of the pack, the various components need merely be inserted into the appropriate bubbles and sealed therein by the lower panel 21. Such ease of manufacture and assembly lends itself to high speed and automatic techniques. 
     As a result of the arrangement of the bubbles 25, 27 and 40, the bag 10 need not be held and stored in an upright position to enable the gas to be generated and dispersed througout the bag. Thus, the bag may be handled in a horizontal position and may be placed in an incubator while disposed horizontally. Accordingly, th bag may be handled more conveniently than has been the case with prior bags of the same general type which require upright storage. The expansion bubble 27 prevents a sudden build up of gas, serves an as overflow chamber for liquid and foam and allows the ampoule 31 and the tablets 33 to fit closely within the bubble 25. The expansion chamber along with the sleeve 37 and the pads 51 and 53 reduce the chances of injury to medical personnel handling the unit.