Patent Number: 044973497
Section: summary

BACKGROUND OF THE INVENTION This invention relates to apparatus for mixing a gas and a liquid, and for dispensing the resultant solution. In some fields, especially the medical field, it is desirable to dissolve a gas in a liquid without loss of the gas and without contamination of the solution. One specific use for the apparatus is the dissolving of a radioactive gas such as xenon-133 in a liquid such as saline to provide a radioactive solution and provide for extraction of a portion of the solution for subsequent use such as tracering in medical analysis. For such applications, the dispenser should also provide radioactive shielding for protection of personnel handling the equipment. One such apparatus is shown in U.S. Pat. No. 3,742,988. In this apparatus, a crushable ampule is positioned in a closed container which is charged with the saline. The ampule is crushed or broken by a lead screw positioned in a cap for the container to permit mixture of the gas and liquid. An inlet line provides for introducing the saline into the container, and an outlet line provides for withdrawing the solution. This prior art device has a number of disadvantages. It is not well suited for use with small volumes, in the order of 5 to 6 cubic centimeters as compared to 30 cubic centimeters. The device requires crushing of the ampule within the container. Also, the gas is mixed with the liquid in the container rather than in the ampule, thereby lowering the concentration of the radioactive gas in the liquid and increasing the possibility of contamination. In another prior art apparatus which has been in use for several years, the larger portion of an ampule is enclosed in plaster, a syringe cap is attached to the ampule neck by a rubber tube, a syringe is coupled to the interior of the rubber tube by a plastic line and a small needle through the syringe cap, and a larger needle with a valve at the outer end is inserted through the syringe cap into the ampule neck to break the ampule seal. This prior art device also has disadvantages. The ampule neck often broke at the time the seal was broken or during subsequent use and there was considerable gas leakage. The unit was akward to assemble and handle, and time was required to initially seal the ampule in plaster. Accordingly, it is an object of the present invention to provide a new and improved apparatus for mixing a gas and a liquid and for dispensing the resultant solution. A particular object is to provide such an apparatus which is especially well suited for handling small volumes, typically 5 to 6 cubic centimeters and less. Another object is to provide such an apparatus wherein the ampule is fully enclosed and protected in a housing and maintained intact, with the liquid being introduced into the ampule for mixing with the gas. An additional object is to provide such an apparatus incorporating a collar for clamping the ampule in place and a cap for sealing engagement with the ampule, with flow paths for gas and liquid within the housing and cap. Other objects, advantages, features and results will more fully appear in the course of the following description. SUMMARY OF THE INVENTION An apparatus for dispensing a gas contained in a sealed ampule by dissolving the gas in a liquid and withdrawing the resultant solution in quantities as desired. The apparatus includes a housing with a cavity for receiving the ampule with the housing having a cap or the like for retaining the ampule, a seat for engagement with the ampule output line, and flow paths from the exterior of the housing to the seat. The apparatus also includes means for connecting a syringe to one of the flow paths. A hollow needle is positioned in the other flow path with an end entering the ampule output line for breaking the seal within the ampule with the resultant inflow of liquid from the syringe into the ampule and dissolving of the gas into the liquid. The gas-liquid solution may then be withdrawn through the needle, with needle flow controlled by a valve carried on the needle. A split collar is positioned about the ampule outlet line for inserting and removing the ampule, and for fixing the ampule in the housing, with the main body of the ampule spaced from the housing and with the mouth of the ampule outlet line engaging the cap in sealing relation.