Medical Liquid Administration Device

Abstract

Positive pressure apparatus for providing an adjustable and reliably constant delivery rate of medical liquids from parenteral applicators, including a self-contained portable medical liquid administration device wherein precisely regulated gas flow through a first flow restrictor operates to pressurize and cause to flow at a substantially constant rate a liquid from a supply through a second flow restrictor which has a flow/pressure drop characteristic such that the liquid flow is essentially independent of gravity-induced pressure fluctuations.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is concerned with improvements in the administration of medical liquids to patients' veins, arteries, and other portions of the body. More particularly the invention provides a device for such administration which is essentially independent of gravity and also assures a uniform flow rate.

2. Prior Art

The administration of medical liquids is largely carried out by gravity-induced hydrostatic pressure infusion of the liquid from a bottle or other container suspended above the recipient an acceptable distance. The flow rate is not easily controlled since variations in relative positions of the receiving portion of the patient and the dispensing bottle may occur with time as the patient or bottle may be shifted about.

Moreover, previously available pressure-assisted administration devices for carrying out intravenous infusions are quite complicated and, when employed, relatively expensive. Previous devices have lacked portability and simplicity. Thus, should a patient require relocation such as from an operating to a recovery room, or from a field emergency unit to a permanent hospital, special, costly and awkward means such as an additional attendant are required. In other cases, such as for cardiac or infant patients, the desired flow rate must prescribed accurately controlled or even deliberately changed from one prescribed rate to another.

In previously known pressurized delivery devices, various sources of pressure including gas and liquid have been used to pressurize a supply of medical liquid to be administered. For example in U.S. Pat. No. 3,044,663 to Norton et al. an auxiliary pressure supply means such as a pump, air pressure tank or gas cartridge is disclosed to be useful in displacing liquid from a container. Similarly, in U.S. Pat. No. 2,842,123 to Rundhaug a collapsible liquid supply is pressurized for subsequent delivery of liquid. In these devices provision for control of flow of the administered liquid is either absent, as in Norton, or operator adjusted as in Rundhaug, either of which can result in unpredictable flow rate conditions depending on the reliability of the pressure supply and/or the skill and attention of the operator.

SUMMARY OF THE INVENTION

It is a major objective of this invention to provide for positive, gravity independent control to a medical fluid delivery system in which a selected flow rate is provided and maintained at all times.

Briefly, and in general terms, the present invention provides, in a medical liquid administration system, means for providing a first fluid at a regulated, constant flow rate to selectively, reliably, and accurately displace a second fluid and cause the second fluid to also flow at a substantially constant flow rate. The invention may also include means for minimizing the effects of gravity-induced hydrostatic pressure upon flow of the second fluid, and may further include means for filtering the second fluid during pressurized flow. One feature of the present invention relates to a new and improved structural assembly incorporating a container for the second fluid together with combined means for filtering the fluid and minimizing fluid flow due to normally encountered levels of gravity-induced hydrostatic pressure.

Accordingly the invention provides a medical fluid administration device which includes a supply of medical liquid and fluid passage mans for connecting the liquid supply to a recipient. A flow-restricting means is provided within the passage having a fixed-flow channel constructed to pass little liquid under only gravity-induced hydrostatic pressure, but to pass the desired liquid flow rate at higher driving pressure. Means is further provided for selectively pressurizing the liquid supply by selecting the particular flow-restricting means through which the driving fluid flows for controlled administering of the driven liquid to the recipient.

The medical (second) liquid may be carried in a pressure-collapsible container for displacement by a compressed gas (first liquid) operating thereon for pressure displacing of the second liquid therefrom.

Thus there may be provided in accordance with the invention a medical fluid administration device which includes a container for medical liquid having a collapsible volume and a liquid outlet, and connector means defining a liquid passageway from the container outlet, the passageway terminating in or with an applicator. A flow restrictor is mounted within the passageway, the restrictor having a fixed-flow channel, to permit the desired flow of liquid when subjected to a pressure exceeding that induced by gravity. Pressurizing means is provided for contracting the volume of the container to expel the liquid therefrom at a predetermined pressure, including a controllably releasable high-pressure fluid supply.

Valve means are provided for controlling pressure and flow rate of the driving fluid, the latter preferably being achieved through use of a porous plug in the passageway providing narrow and tortuous flow paths of great effective length relative to the axial flow path through the plug. A plurality of such plugs may be provided, each providing a different effective flow rate/pressure drop characteristic and mounted for alternate registration with the driving fluid passageway. Further features include quick-fill means for rapidly pressurizing the container at the desired pressure level.

The pressurizing means may further include a variable-volume driving fluid receiver in pressure transmitting contact with the driven or second fluid container which cooperates with contracting means to contract the second fluid container upon a corresponding increase in the volume of the driving fluid receiver. The contracting means may take the form of inextensible material partially or totally circumscribing the volume of the second fluid container and the first fluid receiver whereby an increase in volume of the first fluid receiver decreases the volume of the second fluid by a corresponding amount. The first fluid receiver and second fluid container may be each formed separately of thin inextensible plastic sheeting or be formed thereof with a common wall. In either event a rigid frame may surround the receiver and container to define their maximum combined volume and to protect them from external disturbances.

Still other features include provision of means associated with the driving fluid supply in a manner to meter predetermined amounts of this fluid corresponding to a quantity of second fluid to be displaced from the container and means for indicating occurrence of flow in the second fluid passage means at a portion thereof which is transparent. Such indicating means may also indicate flow rate.

Currently desired micron-sized particle filtering of medical liquids is easily accomplished by the present invention, because of the higher pressures available, in a medical liquid administration device in which the driven fluid flows from a supply thereof along a passageway into a user, by provision of means for filtering minute foreign solid material from this fluid in the passageway.

These and other objects and advantages of the invention, as well as the details of illustrative embodiments, will be more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagrammatic representation of a system incorporating the invention;

FIG. 2 is a table illustrating pressure conditions in FIG. 1;

FIG. 3 is a graph of fill pressure versus time;

FIG. 4 shows one form of flow restrictor selector apparatus;

FIGS. 5-8 are sections illustrating various forms of gas and liquid defining zones usable in the FIG. 1 system;

FIG. 5a is an end view of the FIG. 5 housing;

FIG. 9 is a perspective showing advantageous packaging of the invention;

FIG. 10 is an end view of the FIG. 9 package;

FIG. 11 is an enlarged section taken through the flow restrictor rotary selector of FIG. 9;

FIG. 12 is a section taken on line 12--12 of FIG. 11;

FIG. 13 is an enlarged section taken on line 13--13 of FIG. 9;

FIG. 14 is a section showing a flow indicator;

FIGS. 15a and 15b illustrate another flow indicator;

FIG. 16 is a section showing a modified indicator; and,

FIG. 17 is a section showing a check valve.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring first to FIG. 1, the illustrated system includes a driving fluid contained in a pressure reservoir 10 the outlet of which is connected at 11 to the inlet of a pressure regulator 12. The reservoir 10 may for example consist of a small bottle of two-phase (liquid-vapor) carbon dioxide or other high-pressure fluid, as a source of driving energy. The pressure regulator 12 reduces the pressure of the driving fluid from a lever p.sub.1 to a level p.sub.2, as indicated, and the latter may be varied within limits by adjustment of the regulator control 13. Normally, p.sub.2 is much less than p.sub.1, as is stated in the FIG. 2 table of preferred conditions.

The fluid at pressure p.sub.2, then flows via connection 14 to and through a flow restrictor R.sub.1, FIG. 1 showing several of same grouped at 15 and individually labeled at 15a, 15b, and 15c. Merely for purposes of illustration, inlet valves are indicated at 16a, 16b and 16c as operable to control the flow to pass to and through any of the restrictors. The latter permit different flow rates corresponding to the pressure setting p.sub.2. Such flow rates may vary over a wide range; and the design of the restrictors may be made to accommodate that range as by varying the lengths or cross-sectional areas, or both, of the restrictors as well as choosing materials of different porosity. FIG. 4 shows three restrictors 15a, 15b and 15c of different lengths in parallel passages 17a, 17b and 17c formed in a block 18. A valve unit 20 having branches 21 and 22 is movable relative to the block to selectively register passages 23 and 24 in those branches with the passages 17a-17c. Preferably valve unit 20 is rotary, and one form of rotary unit will be described subsequently.

As referred to, it is the purpose of the flow restrictors R.sub.1 to set the uniform rate of flow Q (usually very low) of the driving fluid flowing at 33 to a zone 30 wherein contained pressure p.sub.3 is operable to drive fluid from a fluid zone 31 at uniform rate, the rate Q being primarily determined by the pressure drop (p.sub.2 -p.sub.3) across the restrictor R.sub.1. Accordingly, there are different rates of flow Qa, Qb and Qc for example, associated with the different restrictors 15a, 15b and 15c. Intermediate flow rates may be obtained by adjusting the control 13 on the pressure regulator 12, which may for example adjust the spring tension in the regulator. The latter may be of spring and diaphragm type, and one example is that known commercially as Model 11-039, manufactured by The Norgren Company of Littleton, Colo. The regulator is such that p.sub.2 is maintained despite large changes in p.sub.1, whereby the flow rate is kept uniform; however, the sizes or capacities of reservoir 10 and zone 31 may be so related that the reservoir exhausts just before zone 31 becomes exhausted, providing automatic shutoff.

The flow restrictor or restrictors R.sub.1 may, for example, consist of ceramic material or sintered metal, both of which are porous. While needle valves could be used, they tend to be contamination sensitive at low flow rates, and are not preferred. Note also the use of safety valves 32 and 32a connected to lines 11 and 33 in FIG. 1. Valve 32 is opened to relieve remaining pressure in reservoir 10, in response to opening of a container indicated at 34 containing fluid zone 31, in order to insure that the reservoir 10 cannot be reused without replacing with a full unit. Also, reservoir 10 may take the form of a metal cartridge which may be automatically disconnected from line 11 as by retractor 36 in response to opening of the container 34. Safety valve 32a operates to relieve pressure in line 33 should it inadvertently exceed a preset level.

Reference to FIG. 5 shows that the preferred driving and driven fluid zones are formed by separate and abutting collapsible containers 40 and 41, respectively, having a large common interface. These are housed within a rigid container or frame having upper and lower sections 42 and 43. The upper section may be removed to permit removal of an exhausted driven fluid container and insertion of the new driven fluid container 41 over the driving fluid container 40, which is typically, at such time, in a deflated state or caused to be deflated by opening valve 32a. It then becomes necessary to rapidly fill driving fluid into the deflated container 40 so that normal flow of driven fluid from container 41 may be resumed or commenced. Such driven fluid flow passes via line 44 containing flow restrictor R.sub.2 to a tip 45 (such as a needle) for delivery.

FIG. 1 illustrates a highly advantageous quick-fill system which may be used to rapidly fill zone 30, i.e. container 40 in FIG. 5, with driving fluid. As seen in FIG. 1, it includes flow restrictors R.sub.3 and R.sub.4 connected in series at 46, restrictor R.sub.3 having its inlet connected at 47 to line 14 via a valve 48. Similarly, line 46 is connected at 49 to the inlet to zone 30 via a valve 50. Finally, the outlet of restrictor R.sub.4 is connected to atmosphere. The flow resistance r.sub.3 of restrictor R.sub.3 is made much less than r.sub.1 of a selected operating restrictor R.sub.1, so that the driving fluid readily flows via lines 47, 46 and 49 to the zone 30 when valves 48 and 50 are open. Also, the flow resistance r.sub.4 of restrictor R.sub.4 is so related to the r.sub.2 of restrictor R.sub.2 that the following relationship is established:

r.sub.4 /r.sub.2 =r.sub.3 /r.sub.1 (1)

Under these conditions, the pressure p.sub.3 will increase from a value p.sub.0 to the operating value L in a short time t.sub.1, as seen in FIG. 3.

When a particular restrictor R.sub.1 (15a-15c) is chosen to establish the desired operating pressure p.sub.3, a corresponding restrictor R.sub.3 (19a-19c, respectively,) is selected (as by appropriate valving 180a-180c operatively connected to valving 16a-16c) to provide the proper flow resistance in accordance with equation (1), so that the operating value L is rapidly obtained.

FIGS. 6-8 show alternate forms of containers for the gas and liquid zones 30 and 31. In FIG. 6, a single flexible container 52 contains both zones separated by a common pressure transmitting wall 53, and within a rigid frame or enclosure 54. In FIG. 7 the liquid zone 31 is formed by a flexible container 54a, and the gas zone 30 is formed between that container and the rigid, fluid tight enclosure 55. In FIG. 8 both gas and liquid zones 30 and 31 are open to the interior of container 56, with a gas-liquid interface at 56a. Automatic shutoff is important to the latter to prevent unwanted feeding of gas such as carbon dioxide to a patient upon exhausting of liquid from zone 31. In all of these forms, the use of a rigid outer housing or frame enclosing zones 30 and 31 is important to prevent inadvertent squeezing of the containers (such as 40 and 41 in FIG. 5), i.e. pressurization of the zones. Also, the fixed shape of the housing or frame defines limits of container pressurized displacement to limit delivery of liquid to the outlet.

FIG. 1 also illustrates the provision of a gage to directly indicate the relative displacement status of the zones 30 and 31. Advantage is taken of the movement of interface 60 between the zones to indicate such status, through use of a marker 61 driven by that interface (say up and down) and adjacent to the calibration indicia 62. FIG. 5a shows an application of this in the FIG. 5 embodiment, wherein the end wall of the case or housing is slotted at 65 to pass the marker element 66 to the exterior from the interior. The marker shank is held between the containers 40 and 41, as at interface 67, and there are calibration markings on the housing to indicate the volume of fluid in the container 42.

Referring back to FIG. 1, the apparatus illustrated is well adapted to use in administering parenteral or other solutions (as for example intravenous infusions) to an animal or human patient, and typically a needle 45 is employed for this purpose. In such event R.sub.2 is constructed to provide a pressure drop (p.sub.5 -p.sub.4) sufficient in relation to gravity induced hydrostatic head changes that might occur during administration that the latter changes are not of critical significance as respects flow rate. (Such flow rate may be correlated with pressure and indicated by the gage 70 connected in line 14, and suitably calibrated.) On the other hand, the pressure drop (p.sub.2 -p.sub.3) afforded by restrictor R.sub.1 is much greater than the drop afforded by R.sub.2. As a consequence, flow rate is primarily controlled by R.sub.1, and only secondarily controlled by R.sub.2, but at the same time R.sub.2 assures that the gravity induced hydrostatic head fluctuations stemming from patient movement relative to the apparatus of FIG. 1 and vice versa and will not affect the flow rate to any significant degree. Also, R.sub.2 may be constructed to provide filtering action to insure delivery of fluid free of foreign particle contaminant. Such construction will be described later. By way of example only, the hydrostatic head fluctuations at the needle 45 would usually be less than one-half p.s.i., and the pressure p.sub.4 would usually exceed 3 p.s.i.

Finally, FIG. 1 illustrates the use of a shutoff and check valve 71 near the needle 45. Further, a bypass line 72 containing a valve 73 is connected across the restrictor R.sub.2, for emergency use. The bypass directs the flow in line 75 around R.sub.2. Alternately, provisions may be made for the emergency complete removal of restrictor R.sub.2.

FIG. 9 shows elements of another form of medical liquid administration device as seen in FIG. 1. A container 100 formed of flexible inelastic plastic sheeting material contains medical liquid and overlies a gas receiving bag 102 also of plastic construction. The container and bag are located within an enclosing rigid frame or housing 103 having upper and lower sections 104 and 105. The latter are hinge connected at 106 for convenience in insertion and removal of successive medical liquid containers 100, and terminals 104a and 105a serve to hold them connected. The container 100 has an outlet 101 at an end thereof for discharge of the container contents. Outlet 101 is fluid tightly connected to tubing 108 which terminates at its opposite end in an applicator needle 120. Between the needle 120 (or other device such as a catheter for administering fluids) and outlet 101, the tubing 108 is provided or bisected with a flow restrictor filter 122, the construction and operation of which are described in detail hereinafter, but which broadly has the function of obstructing partially the passageway defined by tubing 108 to passage therealong of liquids permitting desired flow rates only when driving pressures are well in excess of those created by gravity and thus cooperating with the pressurizing system to be now described in providing controlled administration of medical liquids.

The medical liquid-administering device herein is advantageously portable, compact and self-contained. A pressurized driving fluid supply meeting these requirements is contained in a cartridge in which is stored liquefied CO.sub.2, fluorocarbons or hydrocarbons contained under pressures required to maintain liquid-gas equilibrium, or gases such as N.sub.2 under very high pressure. While other sources of gas may be used herein, for maximum operating convenience, universal commercial availability and inherent portability, I prefer these cartridges. Note FIG. 9 illustrates use of such a cartridge 124 encased in a close-fitting mounting holder 126. The holder is provided at its upper end with a puncture tip conduit (not shown) adapted to receive, gastightly, the outlet neck of the cartridge in the well known manner. Pressure regulator 132, corresponding to that described at 12 in FIG. 1, is located as shown in FIG. 9, to be enclosed along with holder 126 when cover section 104 is in the position seen in FIG. 10. Note also the location of the pressure gage 128 (corresponding to gage 70 in FIG. 1) at one end of the package, as seen in FIG. 10. Gage 128 connects to conduit 130. Note also the bounding walls 180-183.

The control of the rate of flow of driving fluid, which rate is determinative of the rate thereof entering driving fluid receiver 102 and thus the rate of displacement of medical driven fluid into the recipient from container 100, is accomplished in conjunction with the downstream driven fluid pressure (which is set by appropriate adjustment of the pressure regulator 132) and also independently of normal variations of the pressure downstream of the flow rate control point. This is achieved by the use of the flow limiting restrictor within a cylindrical body 140 having fixed end segments 140a and a rotatable center 140b. These body segments may be fastened at 138 and sealed with ring seals 141, as seen in FIG. 11.

The flow rate restriction is obtained by passing the gas along relatively narrow paths within the valve body 140 which tend to impede gas flow. In the illustrated preferred embodiment, a porous plug 142 in passage 144 is used as the gas-flow-restricting means, such plug providing a multiplicity of narrow and tortuous paths for gas flow whereby flow resistance is reliably controlled. Because various rates of flow may be desirable for different operating conditions, a plurality of driving fluid flow passages 144 may be provided for plugs 142 of varying restrictive characteristics. Thus, with reference to FIGS. 11 and 12 the center segment 140b of the valve body is bored to have passages 144a, b, c and d therethrough. Passages 144a, b, and c are each provided with a gas flow restrictive porous plug 142 of different effective flow rate/pressure drop characteristic e.g. through difference in construction, diameter or, as illustrated, length of the plug whereby different rates of gas flow may be had by rotation of the center segment 140b around fastener 138 to index one or the other of the passages to the single bore continuation of conduit 130 in the end segments 140a.

A nonrestrictive flow passage 144d is provided as a bypass for unrestricted gas flow to rapidly provide gas pressure e.g. at startup of the device. In this regard, the quick fill bypass of FIG. 12 does not appear in the FIG. 11 sectional view. To insure against accident, separately actuable means are provided, best shown in FIG. 12 for activating the quick fill. As there shown, the valve body segment 140b is provided with a radial channel 146 in which there is positioned a push pin 148 having an enlarged outer end 148a for finger engagement and a reduced diameter inner end 150 axially slotted at 150a to move radially of the fastener 138 about which the valve segment 140b rotates. Finger depression of the pin 148 against tension spring 152 aligns aperture 154 of the pin with bypass passage 144d for quick fill gas flow. Inadvertent depression of the pin 48 may be prevented by a suitable lock (not shown) which may be gas pressure operated.

A further safety feature as seen in FIGS. 10 and 11 is found in the provision of a relief valve 160 in conduit 131 which is set to insure no greater than some predetermined pressure, this valve corresponding to that seen at 32a in FIG. 1.

Having described the pressurizing means to include illustratively a source of positive pressure such as and preferably a miniature liquefied gas cylinder or cartridge, a pressure regulator and a gas flow restrictor combination which operates independent of normal variations of downstream gas pressure, reference is now made to FIGS. 9 and 13 for the ensuing discussion of the driven fluid flow restrictor aspect of the invention.

To remove operator error as a source of difficulty, the present device employs a fixed-flow-channel-type restrictor. For this purpose FIG. 13 illustrates a ceramic porous cylindrical plug 162, which is the preferred form of flow restrictor 122. Other flow-restricting devices including porous plugs formed of other natural and/or synthetic materials, fused or bonded or otherwise held in rigid configuration may be used. Membranous materials are generally insufficiently strong to withstand the applied pressures contemplated herein for satisfactory periods, but, if properly supported, may be employed.

A highly advantageous aspect of the use of finely porous plugs or similar type flow restrictor 122 is the opportunity to filter from the to-be-administered fluid foreign matter which occasionally is present therein. For this purpose channels 164 may have a size of 0.1 to 5 microns or more or less, these values being illustrative.

Whatever the material of construction of flow restrictor 122, the flow rate/pressure drop characteristic is desirably controlled for particular effects. For example, flow restrictors intended to have a filtering function may have a characteristic of less than 200 ml./hr./p.s.i., but this only by way of example. Every flow restrictor, of course, will have a characteristic to reduce to small degree the significance of gravity on flow of fluid to the recipient.

Reference is now made to FIGS. 1 and 14 showing a flow indicator 79 in the form of a thin disc 80 in the path of liquid flow in the line 75. The thin disc 80 includes a rigid stem 80a which is connected to one end of an elastic or springlike filament 81, the opposite end of which is suitably fixed in the line or tubing 75. As flow increases, the thin disc moves downstream, due to the elasticity or spring action as indicated by broken lines 82, and can be seen when the tubing is transparent. Calibrated indicia 83, mounted on and adjustable lengthwise of the tubing 75, may be provided to afford flow rate information. Also, the downstream flow line may be temporarily clamped to see if disc 80 snaps back, to confirm the existence of flow. FIGS. 15a and 15b illustrate another flow indicator in the form of a thin disc 85 having a rigid stem 85a secured to one end of an inelastic filament 86. As flow commences, the disc 85 oscillates in the tubing, as between FIG. 15a and 15b positions, higher frequency indicating greater flow rates. FIG. 16 shows a combination of the FIG. 14 and 15 concepts, and wherein the disc element 80a stretches on spring element 81a to show flow rate; and in addition the oscillator element 85a oscillates on filament 86 (mounted on disc 80a) to confirm the existence of flow. The thin disc elements 85 and 85a may take other forms, e.g., small spheres, cylinders, grooved cylinders so long as there is clearance between the tube and the element. Also, the tubing containing the elements such as 85, 85a, 80 and 80a should be circular and may consist of a short section of glass tubing. FIG. 17 illustrates a type of check valve 90 that may be used in line 75 near needle 45, to prevent back-flow. The valve has flaps 91 which spread to pass flow to the right, but close together to block reverse flow.

It will be apparent that appropriate alarm devices (not shown) may be utilized wherever system parameters are monitored, e.g. as at 70, 32a, 62 and 79 in FIG. 1, to indicate malfunctions, unsafe, or undesirable conditions.

While particular forms of the invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited, except as by the appended claims.

Claims

I claim:

1. In parenteral liquid administration apparatus, the combination comprising:

a. container means having a first zone to receive a pressurized first fluid and a second zone for a supply of a deliverable second fluid, said zones extending in such confined and pressure-transmitting relation that the second fluid remains pressurized by the first fluid as the second fluid zone diminishes and the first fluid zone expands;

b. means to deliver said first fluid to said first zone and including a fluid pressure regulator and variable flow restrictor means connected in fluid-flow-transmitting relation between said regulator and said first zone; said flow restrictor means having selector means for providing a predetermined but variable pressure drop/flow rate characteristic; and

c. a conduit for delivering said second fluid for administration to a patient from said second zone.

2. In parenteral liquid administration apparatus, the combination comprising:

a. container means having a first zone to receive a pressurized first fluid and a second zone for a supply of a deliverable second fluid, said zones extending in such confined and pressure-transmitting relation that the second fluid remains pressurized by the first fluid as the second fluid zone diminishes and the first fluid zone expands;

b. means to deliver said first fluid to said first zone and including a fluid pressure regulator and flow restrictor means connected in fluid-flow-transmitting relation between said regulator and said first zone;

c. a conduit for delivering said second fluid for administration to a patient from said second zone; and

d. means for selectively bypassing said flow restrictor means.

3. The combination of claim 1 wherein said container means comprises first and second collapsible containers respectively defining said first and said second zones and having a pressure-transmitting and movable interface between said zones.

4. The combination of claim 3 including means confining said container means in said pressure-transmitting relation whereby said interface is movable relative to said confining means in response to fluid flow from the second container during collapse thereof.

5. The combination of claim 4 including an indicator having operative connection to said interface to move therewith.

6. The combination of claim 1 wherein said first fluid delivery means includes a liquefied gas container having an outlet in communication with said pressure regulator.

7. The combination of claim 6 including liquefied CO.sub.2 in said liquefied gas container.

8. The combination of claim 1 wherein said flow restrictor means includes multiple restrictors mounted for selective connection in said fluid-flow-transmitting relation.

9. The combination of claim 8 wherein each of said multiple restrictors comprises a porous plug.

10. In parenteral liquid administration apparatus, the combination comprising:

a. container means having a first zone to receive a pressurized first fluid and a second zone for a supply of a deliverable second fluid, said zones extending in such confined and pressure-transmitting relation that the second fluid remains pressurized by the first fluid as the second fluid zone diminishes and the first fluid zone expands;

b. means to deliver said first fluid to said first zone and including a pressure regulator and first variable flow restrictor means connected in flow-transmitting relation between said regulator and said first zone; said flow restrictor means having selector means for providing a predetermined but variable pressure drop/flow rate characteristic; and

c. means to deliver said second fluid for administration to a patient from said second zone and including a conduit and a second flow restrictor means connected in flow-transmitting relation with said conduit;

d. said restrictors characterized in that the first fluid pressure drop across said first restrictor means substantially exceeds the second fluid pressure drop across said second restrictor means whereby the second fluid flow rate in said conduit is maintained substantially uniform and independent of normal gravity induced pressure fluctuations.

11. In parenteral liquid administration apparatus, the combination comprising:

a. container means having a first zone to receive a pressurized first fluid and a second zone for a supply of a deliverable second fluid, said zones extending in such confined and pressure-transmitting relation that the second fluid remains pressurized by the first fluid as the second fluid zone diminishes and the first fluid zone expands;

b. means to deliver said first fluid to said first zone and including a pressure regulator and first flow restrictor means connected in flow-transmitting relation between said regulator and said first zone;

c. means to deliver said second fluid for administration to a patient from said second zone and including a conduit and a second flow restrictor means connected in flow-transmitting relation with said conduit;

d. said restrictors characterized in that the first fluid pressure drop across said first restrictor means substantially exceeds the second fluid pressure drop across said second restrictor means whereby the second fluid flow rate in said conduit is maintained substantially uniform and independent of normal gravity induced pressure fluctuations; and

e. means for selectively bypassing said second flow restrictor means.

12. The combination of claim 10 wherein said container means comprises first and second collapsible containers respectively defining said first and second zones and having a pressure-transmitting and movable interface between said zones.

13. The combination of claim 12 including means confining said containers in said pressure-transmitting relation whereby said interface is movable relative to said confining means in response to fluid flow from the second container during collapse thereof.

14. The combination of claim 13 including an indicator having operative connection to said interface to move therewith.

15. The combination of claim 10 wherein said flow restrictor means includes multiple restrictors mounted for selective connection in said gas-flow-transmitting relation.

16. The combination of claim 15 wherein each of said multiple restrictors comprises a porous plug.

17. The combination of claim 10 including a bypass connectable between said regulator and said first zone and including other flow restrictor means of lower flow resistance than said first flow restrictor means in series with said bypass and characterized that said first fluid is rapidly flowable to said first zone to pressurize same to a level substantially equal to the pressure normally at the outlet side of said first flow restrictor means when said bypass is not connected.

18. The combination of claim 17 wherein said other flow restrictor means includes third flow restrictor means and fourth flow restrictor means in series, said first zone being connected in flow-transmitting relation to a point between said third and fourth flow restrictor means with said third restrictor means being in parallel with said first restrictor means, the ratio of the flow resistance of said first flow restrictor means to said third flow restrictor means being the same as the ratio of the flow resistance of said second restrictor means to said fourth restrictor means.

19. The combination of claim 17 including valve means to selectively connect said bypass between said regulator and said first zone.

20. The combination of claim 10 wherein said second restrictor means comprises a porous plug.

21. The combination of claim 4 wherein said collapsible container confining means comprises a housing having interconnected sections that are relatively separable to permit replacement of said second container, said conduit extending from said second container to move therewith during collapse thereof, and the housing wall containing an opening to pass said conduit and permit said movement thereof.

22. The combination of claim 21 wherein said opening is at one end of the housing, and said pressure regulator and said restrictor means are at one side of the housing and enclosed therein.

23. The combination of claim 21 wherein said restrictor means and said pressure regulator are contained within said housing, and said housing sections have hinge interconnection.

24. The combination of claim 1 and further including flow-sensing means for indicating fluid flow within the apparatus.

25. The combination of claim 24 wherein said sensing means is located within said conduit.

26. A combination as set forth in claim 2, including pressure-responsive means for inhibiting said means for selectively bypassing said flow restrictor means when the pressure at said first zone exceeds a predetermined value.

27. A combination as set forth in claim 3, wherein said container means comprise a flexible bag.

28. The combination of claim 10 wherein said second flow restrictor means is connected to be removable from said flow-transmitting relation.