US 3340871 A
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P 12, 1967 D. A.JE-LLIES 3,340,871
PARENTERAL LIQUID ADMINISTRATION APPARATUS Filed Oct. 22, 1965 FIG. FIG. 2.
INVENTOR I mm 4. Jm 15 A T'TORNEY United States Patent 3,340,871 PARENTERAL LIQUID ADMINISTRATION APPARATUS David A. Jellies, Glendale, Calif., assignor to Don Baxter, Inc., Glendale, Calif., a corporation of Nevada Filed Oct. 22, 1965, Ser. No. 501,739 Claims. (Cl. 128-214) ABSTRACT OF THE DISCLOSURE An improved liquid-regulator means for a parenteral administration system in which a chamber having an inlet and outlet has a variable-head reservoir having an open lower and upper end and is disposed between the chamber inlet and outlet and liquid can be readily dispensed drop-by-drop due to air cushions formed at the respective ends of the reservoir.
This invention relates to a commonly called administration set for administering liquid from a parenteral liquid container to a patient. More particularly this invention relates to an administration set that tells at a glance precisely the liquid flow rate to the patient.
3,340,871 Patented Sept. 12, 1967 ICC spike 6 and venous needle 5 is a means to regulate the Parenteral liquids are usually administered intravenous- 1y to a patient from a suspended container through a flexible tube that leads to a venous needle in the patients vein. In the past, the flow rate through this flexible tube was measured by a so-called drip meter. The number of drops per minute of liquid dropping across an enlarged air chamber between the parenteral liquid container and the patient were counted in much the same way as taking a patients pulse. By knowing roughly how many drops went to make up a cubic centimeter, an approximation of how many cubic centimeters per minute or hour were being administered to the patient could be made. This counting-the-drop method requires considerable nursing time just to find the flow rate to tell if it needs to be changed, and the nurse can keep watch on only a few intravenous administrations at one time.
It is an object of my invention to provide an intravenous administration set that will immediately tell what the liquid flow rate to a patient is without counting drops.
Another object of this invention is to provide an intravenous administration set with a liquid flow rate indicator giving readings directly in flow rates.
These and other objects of this invention will become clear upon further description of this invention with reference to the drawings, in which:
FIGURE 1 is a front elevational view of the flow rate indicating administration set connected to a parenteral liquid container;
FIGURE 2 is an enlarged sectional view of the flow rate indicator showing a fast flow rate through the ad ministration set; and
FIGURE 3 is a view similar to FIGURE 2 but showing a slow flow rate through the administration set.
With reference to these drawings, the same numerals are used throughout the various figures to represent the same elements. Turning to FIGURE 1, the administration apparatus is shown as providing a liquid channel from a parenteral liquid container 1 to a venous needle 5. This channel includes a first flexible tube 2 with a spike 6 at an upper end thereof connecting to the parenteral liquid container 1. The lower end of flexible tube 2 connects to an inlet of an enlarged chamber 3, which chamber has an outlet connecting to an upper end of a second flexible tube 4. At a lower end of second flexible tube 4 is a means such as adapter 60 for attaching to a venous needle 5.
Somewhere in the administration apparatus between flow of liquid through the administration set. For illustrative purposes, a metal bend clamp 7 is shown in FIG- URE 1 as the flow regulator. This regulator could be any type of roller clamp, screw clamp, valve, etc. and the regulator 7 as shown schematically in FIGURES 2 and 3.
While regulating means 7 can vary the flow rate through the administration set, it has no way of indicating just what the flow rate is. FIGURES 2 and 3 show in an enlarged sectional view the flow rate indicator which is composed of an enlarged chamber 3 having a cylindrical transparent wall 25 partially closed at each end by a top closure 26 and a bottom closure 27. Through closures 26 and 27 are liquid inlet 20 and liquid outlet 21, respectively.
A variable head reservoir 30 with an open mouth 71 at an upper end thereof and with a restricted discharge opening 40 at a lower end is supported by ribs 29 within the enlarged chamber 3 between. its inlet 20 and outlet 21. As liquid flows through inlet 20 and out through drip tube 22 which extends into chamber 3, the liquid is caught in the variable head reservoir 30. Before liquid from variable head reservoir 30 can reach a lower portion of chamber 3 containing outlet 21, it must pass through discharge opening 40 of the variable head reservoir 30. The rate which liquid flows through restricted discharge opening 40 is dependent upon the height or head of liquid in the variable head reservoir 30 and varies as the square root of this head. Thus,'flow rate calibrations directly in cubic centimeters of liquid per minute or hour can be formed directly on variable head reservoir 30.
Just-how the flow rate indicator works can best be explained by taking as an example the slow flow rate shown in FIGURE 3 and then changing this to a fast flow rate shown in FIGURE 2. In FIGURE 3 with regulator 7 set for a very slow flow rate through second flexible tube 4, the flow rate indicator will approach equilibrium with the rate of liquid flow through inlet 20 being substantially the same as the liquid flow rate through outlet 21. As a particular amount of liquid leaves enlarged chamber 3, the same amount of liquid is pulled in. The incoming amount of liquid drops into variable head reservoir 30 establishing a head in reservoir 30 suflicient to force liquid out of discharge opening 40 at the same rate that liquid is leaving outlet 21. At equilibrium the head in variable head reservoir 30 remains at a constant height when regulator means 7 remains unchanged. This height or head gives a direct reading of flow rate.
As shown in FIGURES 2 and 3, the enlarged chambet 3 has an air cushion both above and below variable head reservoir 30. Air pressure in the enlarged chamber 3 adjacent inlet 20 is the same as air pressure adjacent outlet 21. Air passage between ribs 29 allow air to move freely between upper and lower portions of the enlarged chamber 3, thus equalizing air pressure throughout the enlarged chamber 3. A change in liquid flow through flexible tube 4 also changes liquid flow above this air cushion in flexible tube 2, and upon approaching equilibrium flow rates through these two tubes are substantially the same.
Now let us increase the flow rate by opening up regulator 7 to give a faster flow rate as shown in FIGURE 2. When the flow rate through outlet 21 and second flexible tube 4 is increased, this lowers the liquid level at the bottom of enlarged chamber 3. This slight lowering of liquid in the bottom of enlarged chamber 3 creates a verysmall vacuum therein which pulls liquid into the enlarged chamber 3 at a faster rate through inlet 20. As this happens, the variable head reservoir begins to fill, thus increasing its head. The increased head forces liquid Within the reservoir out through discharge opening 40 rate is shown at a glance by calibrations on the variable head reservoir 39.
To decrease the flow rate by closing off regulator 7 somewhat, just the opposite happens. Liquid in the bottom portion of the enlarged chamber builds up slightly, creating a very small pressure in the enlarged chamber 3. This slows down liquid flow into enlarged chamber 3 from inlet 20, which in turn cuts down the flow rate into variable head reservoir 30. As this happens, the head in reservoir 30 drops cutting down on the liquid flow through discharge opening 40. As equilibrium is approached the flow rate through inlet 20, discharge opening 40, and outlet 21 are all decreased but remain substantially the same. The height of liquid in the variable head reservoir 30 has also decreased, indicating a slower flow rate.
For illustrative purposes in the drawings, I have shown the discharge opening-40 in the variable head reservoir 30 as an orifice in the bottom of the reservoir. However, this discharge opening 40 could be of a difierent shape and form. For instance, it might be an orifice or weir groove in the side of the reservoir, the flow through which could be correlated to the height of liquid in the variable head reservoir 30.
Throughout the foregoing specification I have used specific embodiments to describe my invention but it is understood that certain modifications can be made by those skilled in the art without departing from the spirit and scope of this invention.
1. A parenteral administration system comprising in series a parenteral-liquid container, conduit means, venous needle means, and liquid-regulator means intermediately of said conduit means, the improvement in said liquid-regulator means comprising:
an enlarged chamber having an inlet and outlet respectively connected to said conduit means,
said chamber including therein a cuplike, variable head reservoir extending longitudinally between said inlet and outlet and having an enlarged open upper end and a reduced-area lower openmeans supporting said reservoir in said chamber and permitting communication between the lower and upper ends of said reservoir to permit air cushions to be formed thereat; and means connected to said conduit means for controlling liquid flow to said venous needle means.
2. The structure as claimed in claim 1 in which said chamber includes a transparent wall portion, and calibrated indicia on said reservoir whereby drop-by-drop dispensing can be readily determined and regulated.
3. The structure as claimed in claim 1 in which said means supporting said reservoir comprises at least one element integral with the inner surface of said chamber and the outer surface of said reservoir.
4. The structure as claimed in claim 1 in which said reservoir comprises an inverted, substantially frustoconical element, said lower reduced-area opening comprising an elongated passage at the lower end of said reservoir.
5. The structure as claimed in claim 1 in which said chamber inlet comprises a short, drop-forming tube segment extending into said chamber.
References Cited UNITED STATES PATENTS 8/1949 Stevens 73-216 5/1962 Windsor et al 73l94 X