US 2770234 A
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N. M. NESSET ET-AL PARENTERAL ADMINISTRATION OF LIQUIDS Nov. 13, 1956 2 Sheets-Sheet l Filed April 5, 1954 Y INVENTo zal N. M. NEssE-r ET AL 2,770,234 PARENTERAL ADMINISTRATION 0F LIQUIDS 2 Sheets-Sheet 2 Nov. 13, 1956 Filed April 5, 1954 lllllll la nited States Patent 2,770,234 PARENTERAL ADMINISTRATION oF LIQUIDS Naurice M. Nesset, Palatine, and Cyrus R. Eroman, Evanston, lll., assignors to Baxter Laharatories, Inc., Morton Grove, Ill., a corporation of Delaware Application April 5, 1954, Serial No. 421,054
8 Claims. (Cl. 12S-214) This invention relates to the parenteral administration of liquids, and more particularly, to a device for Visually determining that the ow of an intravenous liquid is proceeding at a selected rate. The dispensing device or parenteral administration set of this invention has its greatest utility when used to dispense substantially transparent aqueous solutions, such as saline solutions, glucose and invert sugar solutions, and plasma. However, it can also be advantageously used for relatively opaque fluids such as whole blood.
`This application is a continuation-in-part of our copending application Serial No. 364,684, tiled June 29, 1953.
In the design and operation of parenteral administration sets, it has been found necessary to provide means to admit air to the space above the liquid in the container as the liquid is dispensed for the purpose of equalizing the pressure within and without the container, thereby preventing a negative pressure from building up within the container and stopping the flow of liquid. In some instances, it has been the practice to provide an air tube extending from the air inlet opening in the stopper to a point adjacent the bottom of the container so that when the container is inverted the free end of the tube will project above the surface of the liquid and communicate directly with the air space above the liquid.
It is also desired to provide means which permit the rate of iiow to be selectively varied, and which also makes possible a visual determination that the selected rate is being maintained. In other words, one of the desired elements or" the administration set is some type of ow indicator. The customary flow indicator takes the form of a drip chamber interposed in the conduit from the container to the point of administration. The upper portion of the drip chamber is provided with a nozzle from which the liquid falls a drop at a time into the lower portion of the chamber which is partially filled with the liquid, thus permitting the drops to be counted as a measure of the rate of flow for a given time.
The use of air tubes and drip chambers of the type described has a number of disadvantages both from operational and economic standpoints, but heretofore no satisfactory alternative has been developed.
It is therefore an object of this invention to provide aparenteral administration set which eliminates both the conventonal air tube and drip chamber. More particularly, it is an object of this invention to provide a simpliiied airinlet structure for a container of an intravenous liquid which performs the functions of both the conventional air inlet tube and drip chamber, that is, which both admits air-to the space above the liquid and also provides an accurate indication of the rate at which the liquid is being dispensed. It is a further object of this invention to provide means for admitting air from the exterior of an intravenous solution container to a point beneath the surface of the solution when the container is inverted,
` while at the same time preventing the liquid from leaking out of thecontainer through the air inlet passage. It is "ice 2 a still further object of this invention to provide a means for admitting air in the manner described which is characterized by the further fact that the air is admitted in discrete increments, i. e., separate bubbles, which are of sufficiently large size and suiciently spaced apart to be easily countable, thereby permitting the air bubbles per minute to be counted as a direct measure of the rate of liquid liow. In this connection, it is another object of this invention to` provide an air inlet structure which releases bubbles of air beneath the surface of the fluid during the administration without any substantial variation in the mass of air within each bubble during the course of the administration, and which will therefore compensate for the release of an equivalent volume of fluid at a uniform ratio, for example, say one air bubble per .l cc. of liquid. ln this connection, it is a specific object to provide a parenteral administration set capable of admitting the same number of air bubbles per unit of liquid dispensed irrespective of the rate of liquid flow. Another specic object of this invention is to provide a parenteral administration set having an air inlet structure of the type described which also is adapted to permit maintaining the number of air bubbles liberated per minute at a substantially constant rate during the entire administration, and which is unaifected by the decreasing liquid level in the container. Another object is to provide a modied form of our invention that incorporates both the air inlet passage and the liquid outlet passage in a single connection which permits the use of a container equipped with a single-holed stopper. Further objects and advantages will appear as the specification proceeds.
Specific embodiments of this invention are illustrated in the accompanying drawing, in which- Fig. 1 is a partial elevational view of a parenteral administration set embodying the principles of this invention; Fig. 2, a cut-away perspective view of the container closure and air inlet structure which are largely responsible for the new results achieved; Fig. 3, a perspective view of the air inlet tube of Figs. l and 2; Fig. 4, a cutaway view similar to Fig. 2, but showing a modiiied form of the invention; Fig. 5, a cross-sectional view of an intravenous container equipped with a. plug-in fitting illustrating another embodiment of the principles of this invention; Fig. 6, a cross-sectional operational View of the embodiment of Fig. 5; Fig. 7, a cross-sectional View similar to Fig. 5, showing a modied structure; Fig. 8, a cross-sectional View of an intravenous solution package embodying still lanother form of the present invention; and Fig. 9, a fragmentary plan view of the air-permeable diaphragm incorporated in thev structure of Figs. 5 and 6.
The preferred environmental or cooperating structure for the air inlet means of the present invention can be described as a transparent-walled container having an intravenous liquid therein and adapted to be supported for the administration of said liquid by gravity flow, including means providing an outlet passage for the liquid. In combination with this structure, there is provided in accordance with the present invention means for admitting air beneath the surface of the liquid within the container in visually-observable bubbles at a countable rate directly proportional to the liquid outflow rate through the outlet passage. The advantage and new result thus achieved is that the number of bubbles per unit of time is a measure of the rate of liquid flow.
Looking iirst mainly at Fig. 1, there is shown part of an apparatus for the parenteral administration of an aqueous base liquid including a liquid supply container or bottle A and a conduit means or assembly B, providing a communicating passage extending from container A to the point of administration of the liquid. By way of specific example, container A may have an intravenous saline solution therein which ows downwardly through conduit assembly B into the vein of the patient through a needle (not shown).
1n the specific illustration given, in order to provide for the supporting of container A in an inverted 4position, as shown, it is provided with a recessed ring having a support bail 11 pivotally connected thereto. Container A is also provided with a neck portion 12 enclosing an open mouth which is covered by a closure or cap assembly 13 having a retaining ring 14 which holds plug or stopper member 15 in place.
Stopper 15 is preferably constructed of a resilient flexible material such as soft rubber and is provided with an air inlet opening 16 and a liquid outlet opening 17, as shown more clearly in Fig. 2. When openings 16 and 17 are of the type illustrated, it is customary to pro* vide a diaphragm or seal (not shown) on the outside of the stopper 15, which is removed to prepare the container vfor the administration. Usually a hollow plug-in connection 18 is inserted in opening 17 with its lower end secured `to a flexible hose 19. It is preferable to provide hose 19 with an adjustable clamp for constricting the hose to regulate the rate of flow, for example, a control clamp 20 of malleable metal can be disposed about a portion of hose 19.
In the preferred embodiments of this invention as illustrated in the various figures of the drawing, there is provided a valveless, constantly-open air inlet passage having a substantially constant resistance to the infiow of air at a given flow rate and arranged to admit air beneath the upper surface of the intravenous liquid while it is being administered. Further, the air inlet passage has a portion restricting the inflow of air and providing a liquid seal, and another portion inwardly thereof providing an air collection chamber for releasing air bubbles into the solution. Preferably, the air inlet passage terminates in an outlet within or beneath the neck portions of the containers, and is dimensioned and arranged for releasing discrete, visually-observable bubbles, so that the bubbles will rise from the level of the container neck to theupper surface of the intravenous liquid within the container. l
d In the embodiment of Figs. l to 3, an air inlet tube 221 is inserted into passage 16, as illustrated in Fig. 2. Air inlet tube 21 provides a capillary portion 22 and inwardly therefrom an air collection chamber portion 23. In the illustration given, the air inlet passage through tube 21 gradually enlarges in cross-sectional area above capillary portion 2,2 into air collection chamber 23.
v Air inlet tube 21 and stopper 15, where lthe stopper provides part or all of the air inlet passage, can be formed of a wide Variety of different materials, including plastics, glass, rubber, metals, wood, etc. In other words, the material of construction is not especially critical. However, for simplicity of manufacture it is coni venient tol mold the air inlet tubes from a suitable plastic. Stopper 15 is preferably made of soft rubber.
Although it is not essential for the operation of the embodiment of Figs. lV to 3, it is preferred to provide outwardly of capillary passage 22 a filter chamber 24. Filter chamber 24 receives a wad or ball 25 of airpermeable fibrous material such as loosely intermeshed fibers of cotton. The air entering lter chamber 24 passesthrough filter plug 25 before entering container v A, thereby removing particles of dirt or other solid contaminants in the air which might otherwise enter the solution.
If desired, the outer end of tube 21 can be equipped with akremovable closure. In the illustration. given, the .Outer end of tube 21 is provided with an attached lcap `26of flexible resilient Vmaterial having a hinge portion 27 which permits cap 26 to be seated and unseated without separating it from the tube 21.
Air inlet tube 21 can be adapted to cooperate with stopper 15 in positioning the tube relative to the stopper. For example, air inlet tube 21 is shown provided with d laterally-extending arms 28 and 29, which abut the outer end of stopper 15 when the tube 21 is correctly positioned, as shown more clea'rly in Fig. 2.
Fig. 4 illustrates a modified form of the air inlet tube of Figs. l to 3, the corresponding parts being indicated by the same numbers except that the numbers are primed. The principal difference is that instead of capillary portion 22, there is provided a porous disk or diaphragm 30, providing minute air passages therethrough. By way of specific example, disk 30 can be formed of orcinary filter paper which has been treated with a waterrepellent material like a silicone. In this way disk 30 is made substantially impervious to water while remaining pervious to air, that is, disk 30 is a non-liquidpenetrable, air-permeable membrane.
In the illustration given, air inlet tube 21 is formed in two parts, 21a and 21b, as shown more clearly in Fig. 4. The outer portion 21a has an enlarged bore above annular shoulder 31 into which the outer reduced end of part 21b is received, the two parts being threadedly connected at 32. The outer edge portion of disk 30 rests on annular shoulder 31 and is clamped thereto by the outer end of part 21b,
If desired, a cotton plug, such as plug 25, can be inserted in chamber 2d', but this is not necessary since disk 30 acts as a filter for the incoming air, and this is one of the advantages of the embodiment of Fig. 4. As in the embodiment of Figs. l to 3, the air passing inwardly through the air inlet passage collects in an air collection chamber, designated by the number 23. Air inlet tube 21 is provided with positioning shoulders 28 and 29 to limit the insertion of air inlet tube into passage 16, but it is not necessary that the positioning shoulders be brought into engagement with stopper 15 as long as a iquid-tight seal is obtained between the walls of stopper passage 16 and the lwalls of the air inlet tube.
A modified form of our invention is shown in Figs. 5 and 6, which is particularly adapted for use with a container equipped with a single-holed stopper 101. Stopper 101 is provided with a single passage or opening 102. Passage 102 is provided with a plug-in fitting 103 which provides a passage 104 for admitting air to container 100 beneath the surface of the liquid therein when the container is inverted, and a separate passage 105 for dispensing the liquid from the container.
In the illustration given, fitting 103 includes a cupshaped body 106 which may be constructed of a molded plastic. Cup-shaped body 106 has a neck-like portion 107 for insertion into passage 102. Cup-shaped body 106 also has a tubular portion 108 enclosing liquid outlet passage 105 for connection to conduit 109.
The inner end of tubular portion 108 is provided with threads for threadedly receiving annular plug or disk 110, which in turn is received on the inside of cup-shaped body 106. At an intermediate point, the inside surfaces of body 106 are offset at 111 and 112 to provide two annular shoulders. A non-liquid penetrable, airpermeable ring 113 has its outer and inner edges respectively supported on shoulders 111 and 112 and clamped thereto by the pressure of plug 110. Plug provides passage 104 for the admission of air, and in the illustration given has an outwardly-extending ring 114 aligned therewith for receiving a cap 115.
As illustrated more clearly in Fig. 6, in operation of the air inlet structure of Figs. 5 and 6, air passes inwardly from passage 104'through membrane 113 into the annular space 116. The inward pressure differential across membrane 113 will cause it to bulge inwardly as shown slightly exaggerated in Fig. 6. This permits the whole area of the diaphragm to act for the transmission of air into annular space 116, and this is important for high rates of flow. Further, this permits membrane 113 to be formed in the manner illustrated more clearly in Fig.9. As illustrated, membrane 113 is formed of a thin plastic film having -a plurality of minute slits or punctur'es 1'17 affronts therethrough. Slits 117 are shown as distributed over the whole surface area, and this is preferred. Membrane 113 alsol acts as a lter.
The innermost portion of the air inlet passage, designated by the number 118, communicates with annular passage portion 116 and cooperates therewith in providing an air collection chamber similar to air collection chambers 23 and 23', as previously described. Passage portion 118 also provides the outlet for the air into the intravenous solution, which outlet is adapted for forming discrete, visually-observable bubbles. It has been found that the size of the bubbles released into the solution can be regulated by proper dimensioning of the outlet opening from the air collection chamber. For example, bubbles containing a volume of approximately 0.1 cc. are
`formed when the outlet opening has a diameter of 0.2 inch.
It is preferred to mold the parts of fitting 103, except for membrane 113 and cap 115, out of plastic such as a phenolic resin, but other materials can be used. It is `ipreferred to adapt iitting 103 for a series hookup. The -outer end portion of air passage 104 can be molded with :a standard Luer taper, as illustrated in the drawing at 119. `This permits conventional needle shank adaptors to be employed as the means for connecting a tube leading from :a second container to a container equipped with the litting 103.
A slightmoditlcation of tting 103 is illustrated in Fig. 7, being designated by the number 103. In this `form, the cup-shaped body 106 is provided with an inwardly-extending skirt portion 106a having internal threads engageable with the threads on the neck of container 100',` as illustrated in Fig. 7. The corresponding elements of the embodiment of Fig. 7 have been given the same numbers as the embodiment of Figs. 5 and 6, except thatthe numbers have been primed, and therefore the previous discussion of the corresponding elements of the embodiment of Figs. 5 and 6 will be seen to apply.
Fig. 8 illustrates a still further embodiment of the present invention, as the complete package would appear. The container 200 is provided with a neck portion 201 having a bead 202 on the outside thereof for use in clamping the closure assembly to the container. The closure employed is like the one described in Falk Patent No.
2,108,583, consisting of an inner clamping ring 203 and an outer clamping ring 204 with a metal disk 205 and l aexible rubber disk 206 therebetween. In the structure described in Patent No. 2,108,583, inner clamping ring 203 holds the rubber stopper in place, and it also has l clamped beneath inner ring 203 and against plug 207.
Plug 207 is provided with a liquid outlet passage 209 and an air inlet passage 210.
Operation The operation of this invention is well illustrated in connection with the embodiment of Figs. 5 and 6. Fig. 6 shows the invention in operation as part of a parenteral administration set, air flowing in through passage 104 and the intravenous liquid being dispensed through passage 105. It will be understood that before this condition is achieved, certain preliminary steps may be desirable, such as clearing the set of air by passing a portion of the liquid downwardly through conduit 109. This can usually be, and in the case of the embodiment of Figs. 1 to 3 is, preferably accomplished while the air inlet passage is capped, for example by cap 115. The liquid will drain out through conduit 109 until suicient'vacuum is developed in the air space above the liquid in container 100 to hold up the column of liquid in conduit 109. The needle -is then inserted in the vein of the patient, and the administration is commenced by removing cap 115 and thereby opening the air inlet passage.
When the air inlet passage is first opened, bubbles will rise rapidly and close together from the air inlet tube until the pressure within the container air space, plus the hydrostatic head of liquid in the container, is sufficient to balance the external atmospheric pressure. Then at this equilibrium condition, for each increment of liquid owing out through the outer passage there will be a definite mass or volume of air transferred to the air space above the liquid in the form of relatively large bubbles and the bubbles will be spaced apart, thus making them easily countable. The number of air bubbles per minute can be selectively controlled by adjusting the clamp or control means on conduit 109 with which it will be understood that the conduit is provided, as illustrated in Fig. l in connection with another embodiment of this invention.
In actual operation, the liquid-impervious character of membrane 113 is largely a safety feature, since normally both annular chamber 116 and bubble-forming chamber 118 will be filled with air. The same is true of capillary portion 22 in the embodiment of Figs. 2 and 3, which provides a liquid seal in the event that liquid descends to the level of capillary portion, although it would not usually do so during normal operation.
It has been found that the rate of liquid administration can be maintained substantially constant during the entire course of administration, and that if the operation of the set is interrupted in any manner, the desired rate will be automatically re-established. If the container is accidentally disturbed by bumping or shaking, the ow will only be temporarily disrupted. The disturbing of the p container may cause the liquid to move downwardly within the air collection chamber. However, as soon as the container is stabilized, the air readily displaces the liquid from the collection chamber, thereby reestablishing the desired conditions for equilibrium operations of the set. At any given setting of the control clamp, the rate of liquid dispensed (hence, the rate of bubble admission) is substantially constant throughout the course of the administration. However, the resistance to ow of air offered by the air inlet passage increases as the rate of air ow increases so that approximately the same number of bubbles is admitted per unit of liquid dispensed for rates of liquid ow commonly used in regulated parenteral administration. For example, administration rates of about one liter per hour have been recognized as the maximum achievable while still permitting the adminis-` trator to count the liquid drops in a drip chamber. We have been able to visually count and thereby ascertain the constancy of the number of bubbles per unit of liquid dispensed for administration rates up to one liter per hour when using an embodiment of our invention adapted to admit ten bubbles of air per cc. of' liquid dispensed.
The operation of the other embodiments illustrated in the drawing is quite similar to that described above in connection with the embodiments of Figs. 5 and 6. With the embodiment of Fig. 8, it will be understood that the outerclamping ring 204 is removed, as are disks 205 and 206. The fluid outlet plug-in connector can then be inserted through membrane 208 into iluid outlet passage 209. The thinness of membrane 208 will permit it to be readily ruptured over opening 209 while remaining intact over the air inlet passage 210. Air will then pass through membrane 208 into passage 210, collecting therein and forming bubbles at the outlet therefrom in the manner previously described for the other embodiments.
It will be apparent from the described mode of operation or this invention that the container, or at least the walls thereof, should be transparent, and that best results are obtained when the liquid within the container is transparent or at least sufliciently translucent to permit the air bubbles to be viewed as they rise through the solution. However, it is possible to use the invention in dispensing relatively opaque liquids such as whole blood, since the air bubbles can be observed as they break through the upper surface of the liquid. Moreover, with liquid suspensions such as blood, the air bubbles perform the additional function of continuously agitating the liquid. Parenteral solution containers are usually' constructed of glass.
While in the foregoing specification specic embodiments of this invention have been described in considerable detailt for purpose of illustration, it will be apparent to those skilled in the art that many of the details set forth can be varied widely without departing from the spirit of the invention.
1. In combination with the closure for an inverted liquid dispensing container, passage-providing means for exhausting liquid therefrom, passage-providing means for admitting air thereto, said air passage means being obstructed by a non-liquid-penetrable, air-permeable membrane, said air passage means including an air collection chamber inward of said membrane, said chamber being provided with a bubble-forming outlet adjacent the liquid l in said container.
2. The combination of claim 1 wherein the bubbleforrning outlet is dimensioned and arranged to form a series of countable bubbles of substantially identical volunie.
3. A closure for a liquid dispensing container comprising a flanged cylindrical body provided with two passages extending lengthwise therethrough and communicating with the atmosphere, one of said passages being obstructed Y by a non-liquid-penetrable, air-permeable membrane, said obstructed passage being provided with a bubble-forming outlet adjacent the liquid in said container.
4. In combination with a transparent-walled container at least partially lled with an intravenous liquid, said container being supported in a mouth-downward position, a single-holed closure for said mouth, a fitting extending through said closure comprising liquid passage means and air passage means separate from said liquid passage means, said air passage means being obstructed by a non-liquidpenetrable, air-permeable membrane and provided with an outlet adjacent said liquid of a size adapted to form a series of countable bubbles of substantially identical voll urne.
5. A iitting for a liquid dispensing container equipped with a single-holed closure comprising a flanged tubular body, one end of which is adapted to be received in airtight engagement into the hole of said closure, the llanged 'portion lof said tubular body being provided with a peripheral skirt extending away from said received end, a
removable, non-liquid-penetrable, air-permeable membrane extending between said peripheral skirt and the outer wall of the unreceived end of said tubular body whereby an annular chamber is formed, means for clamping said membrane in liquid-tight engagement with said peripheral skirt and the outer wall of said unreceived end,
said tubular body being provided with a liquid passage extending longitudinally therethrough and with a separate air passage extending through the said received end and communicating with said annular chamber said air passage at said received end terminating in a bubble forming outlet.
6. The fitting of claim 5 wherein the unreceived end is provided with external threads and wherein the means for clamping said membrane is a molded plastic plug threadably received on said unreceived end, said plastic plug having at least one additional opening therethrough whereby the said membrane is exposed to the atmosphere.
7. A fitting for a dispensing container comprising a molded cup-shaped body having a neck portion extending outwardly the base of said body, said body also being provided with a tubular portion extending inwardly the base of said body, whereby an annular trough is formed by the inner wall of said body and the outer wall of said tubular portion, said body being provided with a pair of passages extending longitudinally thereof, one such passage extending through said neck portion and said tubular portion permitting the removal of liquid from said container, and the second such passage extending through the said neck portion separate from the said liquid passage and communicating with said annular trough terminating in a bubble forming outlet adjacent the liquid in said container, said second passage permitting admission of air into said container, a removable non-liquid-penetrable, air-permeable membrane closing said annular trough to form a liquid-tight chamber, and a plug member removably mounted on said tubular portion bearing against said membrane, said plug being provided with at least one additional opening for exposing said membrane to the atmosphere.
8. The tting of claim 7 wherein the said cup-shaped body is provided with an internally threaded peripheral skirt extending outwardly the base of said body,. said skirt adapting said fitting to be threadably received on the externally threaded neck of a dispensing container.
References Cited in the tile of this patent UNITED STATES PATENTS 2,156,313 Schwab May 2, 1939 2,214,260 Ravenscroft et al. Sept. 10, 1940 2,222,371 Nesset Nov. 19, 1940 2,306,222 Patnode Dec. 22, 1942 2,333,791 Hutchison Nov. 9, 1943 2,435,033 Campbell Ian. 27, 1948 2,556,722 Hersberger June 12, 1951 FOREIGN PATENTS 2,853 Great Britain Feb. 8, 1899 987,076 France Apr. 11, 1951