CA1160528A - Automatic dual rate i.v. administration - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
This invention relates to a new device for use in piggyback I.V. administration sets. The device allows for automatic switching between primary and secondary liquids to be intermittently administered at different rates. The device comprises a first receiving chamber with an inlet for primary liquid, a second receiving chamber with an inlet for secondary liquid, a delivery chamber having a common outlet for both liquids and an intermediate chamber between the delivery chamber and the receiving chambers. The intermediate and first receiving chambers are separated by a hydrophilic micro-porous membrane which when wet, passes primary liquid but not air at the maximum pressure within the device. The membrane is located in the upper portion of the device in position to retain air on the downstream side thereof to prevent back-flow of secondary liquid therethrough. This construction allows for a more efficient and operable device then found with the prior art.

Description

J 16~5~8 1 This is a divisional application of Canadian patent application serial number 360,928 filed on September 24, lg80.
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' 'B'~CRGR'OIJND' 'OF THE' 'INVENTI'ON
This invention relates to intravenous I.V. administra-tion sets, and more particularly to piggyback I.V. sets and devices for use therein which permit automatic switching between two parenteral liquids to be administered at different rates.
Intravenous liquids such as parenteral solutions are administered from a source container thr.ough f.lexible tubing to a needle or catheter in communication with the patient's venous system. In current therapy, it is often desired to administer a first or primary solution such as normal saline or dextrose solution at a slow rate to keep the needle or catheter from clotting. Periodically through the day the primary flow is interrupted and a second liquid such as an antibiotic or other drug is administered through the same needle at a higher flow rate. After the secondary solution is administered, the primary solution resumes. Administration sets administering two such liquids from separate sources through separate tubing, meeting at a Y-site with a common ~single tu~e communicating with the patient,. are commonly.known as-"piggyback" sets. Usual.ly the secondary solution adminlstered at the greater flow rate is also administered at a greater pressure-head by gravity feed from a yreater elevation. A
pump or the like can also be used. Such sets are shown in numerous patents, for example U.S. Patents Nos. 4,105,029 and 4,116,6~6.
Piggyback administration sets are known which include a mechanical or air-locking membrane valve to shut off primary 3~ flow when the secondary liquid is flowing, utiliæing the greater -- 1 -- .
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~ 160528 1 pressure head of the latter. Howeve:r, it is belleved that all such sets rely on a single flow controller such as a roller claim downstream of the Y-site to change the rate of flow desired for the two solutions. Thus the physician, nurse, or other attendant must connect the secondary and adjust the flow rate, and, after the secondary is administered, return and readjust to the primary flow rate. Failure to do so can result in flooding the patient with primary solution.

DESCRIPTION OF THE INVENTION
It is the principal object of the present invention to provide piggyhack administration sets, and devices for use therein, which permit independent setting of different primary and secondary flow rates, automatic shut-off of primary flow during secondary administration, and automatic resumption of pri~ary flow at the correct rate without attendant intervention.
Further objects include provision of administration sets which substantially avoid mi.xing of primary and secondary liquids, vent air while preventing air infusion to the patient, and which allow substantially complete administration of the secondary liquid. Other and further objects and advantages will be apparent from the following more detailed description.
In one aspect, the present invention provides a piggy-back I.V. set comprising primary tubing adapted at one end for connection to a primary liquid source, secondary tubing adapted for connection to a secondary liquid source at a higher pressure head, a ~-site junction deYice for receiving the other ends of said primary and secondary tubings, outlet tubing extend-ing from said junction device for conveying said liquids to a patient, check valve means in the primary liquid flow path for preventing flow of secondary liquid into the primary tubing, first l 16~28 1 adjustable flow rate control means below the junction device for controlling -the higher flow of the secondary liquid, and second adjustable flow rate control means above said first control means for controlling the flow rate of the primary liquid.
The check valve means is preferably an air-locking hydrophilic microporous membrane as more fully described below.
Unlike mechanical check valves, such membrane valves are not adversely affected by the pressure changes caused by the second control means for the primary flow. The first control means for the secondary is preferably a conven-tional roller clamp on the outlet tubing adjustable to the higher flow rate. The second control means may also be a conventional roller clamp on the primary tubing but may be any suitable device for restrict-ing primary flow without restricting secondary flow at its higher rate and pressure. ~Ihere the second control means is located above the Y-site, it is preferred to include in the flow path of the secondary liquid through the set a hydrophilic microporous membrane which when wet will pass liquid but not air.

In a second aspect, the present invention in its preferred form provides a novel junction device for use with conYentional I.V. tubing which comprises primary and secondary receiving chambers with inlets, respectively for primary and secondary liquids, a delivery chamber having an outlet for both liquids, and an intermediate chamber between said receiving and delivery chambers, the primary and intermediate chambers being separated by a microporous hydrophilic membrane which, when wet, passes liquid but not air at the maximum pressures within the chambers, said membrane being located in the upper portion of l 160~28 1 the devlce in position to retain air in contact with its down-stream side when pressure within the intermediate chamber exceeds the pressure within the primary chamber. When connected to conventional I.V. tubing, and with addition of adjustable control devices for primary and secondary flow, the device permits automatic switching between solutions at the different flow rates desired for each.
When the primary flow controller is on the primary tubing above the Y-site, a second microporous hydrophilic membrane should separate the intermediate chamber from either the secondary chamber or outlet chamber, or preferably both, to prevent aspiration of air through a vented secondaxy liquid source after emptying. Both are preferred to provide protection against failure of either membrane. Hydrophobic membrane air vents may also be provided. If a controller for the primary liquid is used which does not produce a sub-atmospheric pressure at the secondary liquid inlet, only the membrane separating the primary chamber is required.
To this end, the inve~tion provides the device for ~ use in piggyback I.V. administration sets to permit automatic switching between primary and secondary liquids to be intermit-tently administered at different rates, said device comprising a first receiving chamber with an inlet for primary liquid, a second receiving chamber with an inlet for secondary liquid, a delivery chamber having a common outlet for both liquids, and an intermediate chamber between said delivery chamber and said receiving chambers, said inte~mediate and first receiving chambers being separated by a hydrophilic microporous membrane which when wet passes primary liquid but not air at the maximum pressure within said device, said membrane being located in the upper l 16~5~8 1 portion of the device in position to retain air on the down-stream side thereof to prevent back-flow of secondary liquid therethrough.
The invention may be better understood by reference to the accompanying drawings in which Fig. l is an elevational view of one embodiment of the invention using check valve membranes in the drip chambers, a conventional Y-site device, and two conventional flow rate control clamps;

Fig. 2 is vertical section through a novel Y-site device for use in a second embodiment of the invention;
Fic3. 3 is a plan view of the top membrane bearing surface of the base of a second Y~site device for use in a third embodiment;
Pig. 4 is a bottom view of the base shown in Fig. 3;
Fig. 5 is a section on the line 5-5 of Fig. 3 with the cove~ of the base shown in exploded sectional view;
Fig. 6 is a side view of the device of Figs. 3-5 with the cover and hydrophilic membranes shown in longitudinal section;
Fig. 7 is a schematic longitudinal section through the device of Figs. 3-6, modified for clarity to illustrate operation in administering primary liquid; and Fig. 8 is a schematic section similar to Fig. 7 illustrating administration of secondary liquid.
Referring to Fig. l/ a piggyback I.V. administration set is shown comprising a source of primary and secondary liquids l~ and 12, respectively, primary tubing 14, secondary tubing 16, a conventional Y-site device 18, and outlet tubing 20 terminating in needle 22 for insertion into a patient's vein. Tubing 14 and l 1~0528 16 terminate in their upper ends with identical dri~ chambers 24 having spikes 26 for connecting to sources 10 and 12 and air vents 28. Drip chambers 24 also include a hydrophilic microporous membrane 25 across the liquid flow paths as shown for example in U.~. patent 4,116,646. The membranes are in contact with air on their downstream side and have a bubble point above the pressures in the system. They therefore, when wet, will pass liquid downstream but will prevent air or liquid from passing upstream. Membranes having bubble points above about 2 psi, for example membranes having about five micron pores, are suitable. The liquid solution in sources 10 and 12 will therefore drain through the membranes but reverse liquid flow and air passage are prevented. The membranes thus serve as check valves and in addition, by preventing ingress of air, will hold a liquid co]umn in each of tubing 14 and 16 and in their respective drip chambers.
The sources may therefore be readily replaced as needed without need for re-priming to remove air.

In normal operation, the primary liquid from source 10 drains by gravity through tubing 14, junctlon 18, tubing 20 and needle 22 to the patient, the low flow rate therefore being regulated by a conventional, adjustable roll clamp controller 30. During flow of primary liquid, secondary liquid {rom source 12, if connected to junction 18, is prevented from flowing by shut-off clamp 32. When it is desired to administer secondary liquid from source 12, which is mounted above source 10 to provide a greater pressure head, the tube 16 i5 connected and shut-off clamp 32 opened. Since its pressure is greater, it will flow through junction 18 and cause primary flow throuyh tubing 14 to cease. Its greater flow rate is controlled by roller 1 16052~
1 clamp controller 34 on outlet tubing 20. Once controller 34 is initially adjusted, it does not require adjusting for subsequent primary flow which is controlled by controller 30.
At the more open setting of controller 34, it will not interfere with the flow established by controller 30.
When the secondary liquid is administered and its flow ceases, its pressure in tubing 16 will drop and primary liquid from source 10 will automatically resume at the rate established by controller 30 and no intervention by an attendant is required to adjust the rate. No air can enter junction 18 through tubing 16 and vent 28, even though tubing 1~ below controller 30 may be at subatmospheric pressure, because it is prevented by whetted membrane 25. No special check valve at junction 18 is required. When subsequent secondary administrations are required, it is necessary merely to close clamp /32, refill or replace source 12, and reopen clamp 32.
If desired, source 12 may be filled with secondary liquid sufficient for several administrations and clamp 32 or similar shut-off device automatically opened and closed with a

2~ timer at the desired intervals. Also, if desired, an optional final filter 36, which can include an air vent, may be inserted in tubing 20 to assure sterility.
While the set shown in Fig. 1 provides automatic switching and differential rate control, membrane check valve 25 in the drip chamber 24 on tubing 16 will prevent draining of the latter which may be desired by the physician making individual secondary administrations. Also, while secondary liquid flowing in tubing 16 cannot flow into tubing 14, mixing of liquids in tubing 14 by diffusion can occur. Where these limita-tions are objectionable, junction 18 and the membrane l 160~28 1 check valves 25 may be replaced with the special units shown in Fig. 2 and in Figs. 3-6.
The junction device 40 shown in Fig. 2 is a modification of the device shown in U.S. patent 3,854,907.
Fig. 2 herein illustrates a vertical, generally diametric section of the modification wherein the top is modified to provide a primary liquid chamber 42 having an inlet 44 for connection to primary tubing 46 and a secondary liquid chamber 48 having an inlet 50 for insertion of a secondary tube 1~ (not shown) throu~h resilient, penetrable seal 52. Chambers 42 and 48 drain into intermediate chamber 54 which is separated by the former by a hydrophilic microporous membrane valve 56.
~hamber 42 also has a hydrophobic vent filter 58.
Central support 60 is of the construction shown in the referenced patent and carries on its outer surface a final sterili~ing filter 74 of a hydrophilic, microporous membrane which will pass liquid but, when wet, will prevent passage of air. Support 60 provides an outlet chamber 62 which communicates with outlet 64 for connection with outlet tubing (not shown) ~ for passing liquid to the patient.
The top of support 60 carries a membrane 66 the center portion of which, as shown in the reference patent, is hydrophobic and provides an air vent to the atmosphere through passageway 68. Optionally, and as shown, the central portion of filter 66 has an annulus 72 sealed between the top periphery of passageway 6~ and the inner surface of the outer wall of device 40. The annulus is hydrophilic and serves as additional protection against air passage from chamber 48 should the final filter 74 fail. The hydrophilic annulus 72 can be provided by using a separate material, or a single hydrophilic disc may be l 160528 used with the central portion renderecl hydrophobic by known procedures, ~or example by treatment with silanes.
In operation, primary liquld from an elevated source enters through inlet 44 to primary cham~er 42, priming or other entrained air being vented at 58. The primary liquid from chamber 42 drains through filter 56 into chamber 54, partially filling chamber 54 but leaving an air layer in downstream contact with membrane 56 to air-lock against reverse li~uid flow. The liquid then drains through the outer annulus 72 of membrane 66 into the annular chamber 70, through the final filter 74 into outlet chamber 62, and then through outlet 64.
The rate of prima~y flow, as in the embodiment of Fig. 1, is controlled by a roll clamp controller ~not shown) on primary tubing 46.
When it is desired to administer secondary liquid, its sources is mounted above the primary source to provide a greater pressure head, its tubing inserted, for example with a hollow needle adapter of known construction, through seal 52, and flow started by releasing the shut-off clamp as illustrated in Fig. 1. Its flow rate, as also shown in Fig. 1, is controlled by an adjustable roll clamp controller on the outlet tubing from outlet 64 to the patient. Secondary liquid will drain fully from its source and tubing into chamber 54 and cannot ~low through membrane 56 into primary chamber 42 because the membrane 56 is air-locked. When the secondary is dispensed, the primary will automatically resume at its predetermined rate and any air drawn through the secondary tubing is ventedthrough passageway 68 and is prevented from reaching outlet 64 by the wetted annulus 72 and ~inal filter 74. Thus, in addition to automatic s~itching and differential rate control, the _ g _ l 160528 1 sec~ndary liquid will Eully drain and no liquid mixing above membrane 56 can occur. All valves are membranes unaffected by negative or sub-atmospheric pressure and no check values external to the junction device as required.
The preferred design for a novel junction device is shown in Fig. 3-6 and its operation illustrated in Figs. 7 and 8. The device comprises a molded base 80 and a molded cover 82. Base 80 has an upper surface provided with circumferential ridges 84, 86 and 88 and ribs 90, the upper surfaces of which define a substantially flat plane. A hydrophilic microporous membrane 92 is sealed thereto by adhesive, heat, or preferably solvent bonding. While three separate membranes can be used sealed to ridges 84, 86 and 88, respectively, a single membrane is preferred. The portion of the membrane occupying the space 93 between the adjacent edges of ridges 84 and 86 is preferably either removed by cutting or the like or is rendered non-porous by impregnation or the like to prevent capillary flow across the space 93. The cover 82 is sealed fluid-tight to the outer periphery 94 of the top of the base to provide an intermediate chamber 126 about 10 mils thick between cover and membrane surface.
The space between the membranes and the top surface of t~e base at the bottom of ribs 90 define a primary chamber 98 ~within ridge 84), a secondary chamber 100 (within ridge 86), and an outlet chamber 102 (within ridge 88), each chamber being, for example, about 25 mils deep. The base 80 has molded therein three pipes 104, 106, and 108, respectively, for connection to primary tubing, secondary tubing, and outlet tubing of a piggyback I.V. set. Pipe 104 terminates in opening 110 constituting an inlet for primary liquid to primary chamber ~ 160528 198, pipe 106 in opening 112 constituting an inlet for secondary liquid to the secondary chamber 100, and pipe 108 terminates in opening 116 constituting an outlet from the outlet chamber 102.
Openings 118 and 120 are provided in the base, respectively in the primary ana secondary chambers, and sealed thereover are hydrophobic microporous membranes serving as air vents in those chambers upstream of the hydrophilic membranes thereover.
10The operation of the device of Figs. 3-6 is illustrated schematically in Figs. 7 and 8. In Fi~. 7, the unit is administering primary liquid 121 through primary tubing 122 at a rate controlled by controller 124. The primary liquid 121 flows into primary chambers 98', through the membrane 92' into intermediate chamber 126' beneath the cover 82'. A air bubble 128 is formed in the upper portion of chamber 126' and prevented from venting by the wetted membrane 92'. Liquid 121 flows from chamber 126 back through the lower portion of membrane 92' into outlet chamber 102' and thence through outlet tubing 130 to the patient.
Fig. 8 illustrates administration of secondary fluid 132 which enters secondary chamber 100' at a greater pressure head than primary liquid 121 and passes through membrane 92' into intermediate chamber 126'. Air bubble 128 covers all of membrane 92' over the primary chamber 98' and prevents back-flow. Secondary liquid 132 passes from chamber 126 through the lower part of membrane 62' into outlet chamber 102' and thence to the patient through tubing 130. The secondary liquid flow rate is controlled by controller 134 at an open setting having little effect on primary liquid flow. Again the secondary fluid can drain completely and cannot mix with primary in the primary -chamber.

l 160~28 1 When the secondary administra-tion is completed, the pressure falls and primary liquid flow res~s automatically at its preset lower flow rate. Any air entering the device through the vented secondary tubing is vented through vent 120.
While redundant membranes are shown between chamber 126 and chamber 100' and 102', it should be understood that either can be omitted and the facing chambers thereby merged.
If the flow rate controller Ior the primary liquid does not produce a negative pressure at the secondary chamber inlet, both membranes between chambers 126 and 100' and 102' may be omitted.
It should be understood that the invention includes all modifications, and equivalents within the scope of the appended claims.

Claims (4)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A device for use in piggyback I.V. administration sets to permit automatic switching between primary and secondary liquids to be intermittently administered at different rates, said device comprising a first receiving chamber with an inlet for primary liquid, a second receiving chamber with an inlet for secondary liquid, a delivery chamber having a common outlet for both liquids, and an intermediate chamber between said delivery chamber and said receiving chambers, said intermediate and first receiving chambers being separated by a hydrophilic microporous membrane which when wet passes primary liquid but not air at the maximum pressure within said device, said membrane being located in the upper portion of the device in position to retain air on the downstream side thereof to prevent back-flow of secondary liquid therethrough.

2. A device as claimed in claim 1 comprising a further hydrophilic microporous membrane separating said intermediate chamber from at least one of said second receiving and delivery chambers, said membranes passing liquid but not air.

3. A device as claimed in claim 1 comprising further hydrophilic microporous membranes separating said intermediate chamber from both second receiving chamber and said delivery chamber.

4. A device as claimed in claim 2 or 3 wherein said membranes are located in substantially the same plane.